Kynurenine aminotransferase and its products for treating inflammatory bowel disease - Patents.com

Abstract

The present invention relates to the treatment of inflammatory bowel disease with kynurenine aminotransferase, live recombinant bacteria that have been genetically engineered to express and secrete said kynurenine aminotransferase, and / or a product of said kynurenine aminotransferase, which is xanthurenic acid, a derivative thereof, or any pharma- ceutically acceptable salt or solvate thereof.

Description

[Technical field]

[0001] The present invention relates to the field of medicines, in particular compositions, for treating inflammatory bowel disease. [Background technology]

[0002] Inflammatory bowel disease (IBD) is a general name used to identify a group of inflammatory disorders of the gastrointestinal (GI) tract, including Crohn's disease (CD) and ulcerative colitis (UC). The exact cause of IBD is not fully understood, but is known to be related to genetic predisposition, dysbiotic imbalance of the gut microbiota, and environmental influences. IBD is characterized by repeated alternating cycles of clinical relapse and remission. In the absence of appropriate treatment, IBD leads to chronic inflammation and therefore irreversible intestinal damage.

[0003] CD can affect any part of the GI tract, but most commonly affects the end of the small intestine (ileum) where it joins with the beginning of the colon. CD can appear in "patches," affecting some areas of the GI tract while other parts remain completely unscathed. In CD, inflammation can spread through all layers of the intestinal wall. UC is limited to the large intestine (colon) and rectum. Inflammation occurs only in the innermost layer of the inside of the intestinal tract. It usually begins in the rectum and lower colon, but can spread and extend continuously throughout the entire colon. In some individuals, it is difficult to determine whether their IBD is CD or UC. In these rare cases, a person is given a diagnosis of indeterminate colitis (IC).

[0004] Some recent studies have revealed that aryl hydrocarbon receptor (AhR) agonists or bacterial probiotics that produce such agonists may have beneficial effects on IBD (see WO 2018 / 065132 and WO 2017 / 032739). However, despite an increased understanding of the underlying disease process, no cure exists. Currently available drugs, such as anti-inflammatory corticosteroids and immune system suppressants, are used to reduce inflammation that causes signs and symptoms. However, the same treatments have significant potential toxicities, including increased risk of infection, increased risk of malignancy, and many patients may lose response if the treatment is used for a long period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO 2018 / 065132 [Patent Document 2] WO 2017 / 032739 [Patent Document 3] U.S. Patent Application No. US2006199246 [Non-patent literature]

[0006] [Non-Patent Document 1] Needleman and Wunsch algorithm;Needleman and Wunsch, 1970 [Non-Patent Document 2] Smith and Waterman algorithm (Smith and Waterman, 1981) [Non-Patent Document 3] Sambrook et al. (Sambrook J, Russell D (2001) Molecular cloning: a laboratory manual, Third Edition Cold Spring Harbor) [Non-Patent Document 4] Morello et al., J Mol Microbiol Biotechnol 2008;14:48~58 pages

Non-patent document 5

Non-patent document 6

Non-patent document 7

Non-patent document 8

Non-patent document 9

Non-patent document 10

Non-patent document 11

Non-patent document 12

Non-patent document 13

Non-patent document 14

[0007] Therefore, there remains a great need for new drugs for use in the treatment of IBD. [Means for solving the problem]

[0008] The inventors herein demonstrate that administration of kynurenine aminotransferase or one of its products, namely xanthurenic acid, results in anti-inflammatory effects in mice suffering from DSS-induced colitis.

[0009] Accordingly, the present invention provides a composition for use in treating inflammatory bowel disease, comprising: - kynurenine aminotransferase (KAT), - a live recombinant bacterium that has been genetically modified to express and secrete said kynurenine aminotransferase, and / or - a product of said kynurenine aminotransferase which is xanthurenic acid, a derivative thereof, or any pharma- ceutically acceptable salt or solvate thereof; The present invention relates to a composition comprising:

[0010] The inflammatory bowel disease is preferably selected from the group consisting of Crohn's disease, ulcerative colitis, indeterminate colitis (IC), other non-infectious gastroenteritis, enteritis, enterocolitis and colitis, and pouchitis, more preferably selected from Crohn's disease and ulcerative colitis. The inflammatory bowel disease may be selected from the group consisting of enteritis, enterocolitis, pouchitis and non-infectious gastroenteritis other than Crohn's disease, ulcerative colitis and indeterminate colitis, or from the group consisting of enteritis, enterocolitis and pouchitis.

[0011] The kynurenine aminotransferase may be selected from the group consisting of human kynurenine-oxoglutarate transaminase 1 (KAT I), human kynurenine / alpha-aminoadipate aminotransferase (KAT II), human kynurenine-oxoglutarate transaminase 3 (KAT III), human mitochondrial aspartate aminotransferase (KAT IV), orthologues thereof, and variants thereof, wherein said variants have at least 80% sequence identity to human KAT I, human KAT II, ​​human KAT III, human KAT IV, or to any orthologues thereof, and exhibit kynurenine aminotransferase activity. In particular, the kynurenine aminotransferase may be selected from the group consisting of human KAT II, ​​human KAT III, human KAT IV, orthologues thereof, and variants thereof, wherein the variants have at least 80% sequence identity to human KAT II, ​​human KAT III, human KAT IV, or to any orthologues thereof, and exhibit kynurenine aminotransferase activity.More particularly, the kynurenine aminotransferase may be selected from the group consisting of human KAT II, ​​orthologues thereof, and variants thereof, wherein the variants have at least 80% sequence identity to human KAT II, ​​or to any orthologues thereof, and exhibit kynurenine aminotransferase activity.

[0012] In a specific embodiment, the kynurenine aminotransferase is selected from the group consisting of KAT proteins of SEQ ID NOs: 1 to 32, and variants thereof having at least 80% sequence identity to any of SEQ ID NOs: 1 to 32 and exhibiting kynurenine aminotransferase activity. In a further specific embodiment, the kynurenine aminotransferase is selected from the group consisting of KAT proteins of SEQ ID NOs: 10 to 16, and variants thereof having at least 80% sequence identity to any of SEQ ID NOs: 10 to 16 and exhibiting kynurenine aminotransferase activity.

[0013] The composition may comprise the kynurenine aminotransferase.

[0014] Alternatively, or in addition, the composition may comprise a recombinant bacterium that has been genetically modified to express and secrete the kynurenine aminotransferase. Preferably, the recombinant bacterium is selected from the group consisting of bacteria belonging to the genera Allobaculum, Adlercreutzia, Anaerostipes, Bifidobacterium, Propionibacterium, Bacteroides, Eubacterium, Enterococcus, Ruminococcus and Faecalibacterium, Escherichia coli, and lactic acid bacteria such as bacteria belonging to the genera Lactobacillus, Lactococcus and Streptococcus.

[0015] Alternatively, or in addition, the composition may comprise xanthurenic acid, a derivative thereof, or any pharma- ceutically acceptable salt or solvate thereof, the xanthurenic acid derivative being of formula (I):

[0016] [ka]

[0017] [In the formula, R1, R2 and R3 each represent a hydrogen atom, a hydroxyl group, a halogen atom, a -CO-R8 group or a -CO2R8 group (R8 is H or C 1~10 alkyl group), -NR9R 9' (R9 and R 9' are independently a hydrogen atom or C 1~10 alkyl group), nitro group, cyano group, or C optionally substituted with a halogen atom 1~10 Alkyl, C 2~10 Alkenyl or C 2~10 C optionally substituted with an alkynyl group and a halogen atom 1~10 independently selected from the group consisting of alkyloxy; R4 and R6 are each a hydrogen atom, and C 1~10 independently selected from the group consisting of alkyl groups; R5 is a hydroxyl group, a hydrogen atom, -NR7R 7' (R7 and R 7' are independently a hydrogen atom or C 1~10 alkyl group), C 1~10 Alkyl groups, and C 1~10 alkoxy groups] or a tautomeric form thereof.

[0018] In particular, the xanthurenic acid derivative is R1, R2 and R3 are a hydrogen atom, an oxygen atom, a halogen atom, or a C 1~10 Alkyl, C 2~10 Alkenyl or C 2~10 alkynyl groups; R4 and R6 are hydrogen atoms and C 1~10 alkyl groups, or R4 and / or R6 are absent; R5 is a hydroxyl group, NHR7, NR7R7, or C 1~10Alkyl or alkoxy group (R7 is a hydrogen atom and C 1~10 The compound of formula (I) may be selected from the group consisting of alkyl groups.

[0019] In particular, the xanthurenic acid derivative may be selected from the group consisting of oxo-xanthurenic acid (OXA) and di-oxo-xanthurenic acid (DOXA). Preferably, the composition comprises xanthurenic acid or any pharma- ceutically acceptable salt or solvate thereof.

[0020] The composition may further comprise nicotinamide adenine dinucleotide or a precursor thereof or may be used in combination with nicotinamide adenine dinucleotide or a precursor thereof.

[0021] The present invention also relates to the use of a composition of the present invention for the manufacture of a medicament for treating inflammatory bowel disease.

[0022] The present invention further relates to a method for treating inflammatory bowel disease in a subject, comprising administering to said subject a composition of the present invention. [Brief description of the drawings]

[0023] [Figure 1] Kynurenic acid (KYNA) and xanthurenic acid (XANA) abundance is negatively correlated with inflammation during DSS-induced colitis. (A) Dynamics of histological score and colon length over the course of colitis, n=8-10. (B) Dynamics of kynurenine pathway metabolites in serum and colon tissue over the course of colitis, n=8-10. [Diagram 2] KYNA and XANA, but not quinolinic acid (QUIN), protect against DSS-induced colitis. Body weight loss (A), DAI (B), colon length (C), histological score (D), colon images (E). Statistical analysis: n = 16-20 mice per group, two-way or one-way ANOVA with Bonferroni post-hoc test. [Figure 3-1] Perivascular injection of KYNA and XANA protects against colitis. Weight loss (A), DAI (B), colon length (C), and histological score (D). Statistical analysis: n=10 mice per group, two-way or one-way ANOVA with Bonferroni post-hoc test. [Figure 3-2] Perivascular injection of KYNA and XANA protects against colitis. Colon image (E). [Figure 4-1] AADAT production in E. coli. pStaby1 plasmid (A) and muAADAT plasmid (B). [Figure 4-2] Induction of AADAT protein production. (C) The following samples were loaded on an acrylamide gel protein: before induction (a); after induction (b) and unstained protein ladder Biorad (c). Visualization of the produced and purified AADAT protein (D). The following samples were loaded on an acrylamide gel: culture supernatant (c); culture pellet (d); flow-through (e), 40 mM imidazole wash (f) and elution fractions (1-8). [Figure 4-3] Assessment of AADAT activity via kynurenine and 3-hydroxykynurenine degradation (E). Conversion of KYNU into KYNA, XANA and other metabolites accompanying our AADAT production (F). [Figure 5-1] AADAT injection protects during DSS-induced colitis. Body weight loss (A), DAI (B), colon length (C), and histological score (D). Statistical analysis: n = 8-10 mice per group, two-way or one-way ANOVA with Bonferroni post-hoc test. [Figure 5-2] AADAT injection protects during DSS-induced colitis. Colon image (E). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The inventors herein demonstrated that in a mouse model of DSS-induced intestinal inflammation, xanthurenic acid (XANA) and kynurenic acid (KYNA) are negatively correlated with inflammation, while kynurenine and quinolinic acid have the opposite kinetics. The inventors further confirmed this result in the human context, where a negative correlation was observed between several markers of Crohn's disease activity and KYNA and XANA. Based on these results, the inventors also showed that oral or perivascular administration of XANA and KYNA in mice undergoing DSS-induced colitis led to less weight loss, lower colitis activity index, longer colon, lower histological score and reduced expression of proinflammatory cytokines, thereby demonstrating the systemic anti-inflammatory effect of XANA and KYNA. Similar results were obtained by perivascular administration of purified kynurenine aminotransferase, specifically alpha-aminoadipate aminotransferase (AADAT or KAT II), in a mouse model of DSS-induced colitis. The results showed that even at the lowest doses, protection against inflammation in terms of weight loss and clinical scores, but also in colon length or histological scores. Thus, the inventors herein demonstrate that administration of kynurenine aminotransferase or xanthurenic acid shows strong therapeutic potential for treating or preventing inflammatory bowel disease.

[0025] Thus, in a first aspect; the present invention relates to a composition for use in the treatment of inflammatory bowel disease. It also relates to the use of the composition for the manufacture of a medicament for treating inflammatory bowel disease. It further relates to a method for treating inflammatory bowel disease in a subject, comprising administering to said subject the composition.

[0026] The composition comprises: Kynurenine aminotransferase, and / or - a live recombinant bacterium that has been genetically modified to express and secrete said kynurenine aminotransferase, and / or - xanthurenic acid or a derivative thereof, or any pharma- ceutically acceptable salt thereof may include:

[0027] In particular, the composition comprises: - kynurenine aminotransferase; or - a live recombinant bacterium that has been genetically modified to express and secrete the kynurenine aminotransferase; or - xanthurenic acid or a derivative thereof, or any pharma- ceutically acceptable salt thereof; or - (i) a kynurenine aminotransferase and (ii) a live recombinant bacterium that has been genetically modified to express and secrete said kynurenine aminotransferase; or - (i) kynurenine aminotransferase and (ii) xanthurenic acid or a derivative thereof, or any pharma- ceutically acceptable salt thereof; or - (i) a live recombinant bacterium that has been genetically modified to express and secrete said kynurenine aminotransferase, and (ii) xanthurenic acid or a derivative thereof, or any pharma- ceutically acceptable salt thereof; or (i) kynurenine aminotransferase, (ii) a live recombinant bacterium that has been genetically modified to express and secrete said kynurenine aminotransferase, and (iii) xanthurenic acid or a derivative thereof, or any pharma- ceutically acceptable salt thereof. may include:

[0028] As used herein, the term "kynurenine aminotransferase" or "KAT" refers to an enzyme that catalyzes the transamination of kynurenine to form kynurenic acid and / or the transamination of 3-hydroxykynurenine to form xanthurenic acid.

[0029] As used herein, "KAT activity" refers to the catalysis of transamination of kynurenine to form kynurenic acid and / or the catalysis of transamination of 3-hydroxykynurenine to form xanthurenic acid, preferably the catalysis of 3-hydroxykynurenine to form xanthurenic acid. KAT activity can be assessed by any method known to those skilled in the art. For example, KAT activity could be assessed as described in the experimental section, i.e., the assay based on the disappearance of kynurenine and / or 3-hydroxykynurenine. Briefly, reaction mixtures (final volume 50 μL) containing 10 mM L-kynurenine or 3-hydroxykynurenine, 2 mM α-oxoglutarate, 40 μM PLP (pyridoxal 5'-phosphate) and 0 or 1 μL of the protein to be tested prepared in a buffer of 100 mM potassium phosphate (pH 7.4) are incubated at 37°C for 15 minutes. The reaction is stopped by adding an equal volume of 30% acetic acid. The supernatant of the reaction mixture obtained by centrifugation at 3000 g for 10 min at 4° C. is mixed equally with Ehrlich's solution and incubated at room temperature for 15 min to obtain a colorimetric reaction. In parallel, a standard range of kynurenine or 3-hydroxykynurenine from 0 μM to 1000 μM is made under the same conditions. The amount of kynurenine or 3-hydroxykynurenine present in the sample is measured at OD of 492 nm using a spectrophotometer and calculated using the standard range. The disappearance of kynurenine and / or 3-hydroxykynurenine indicates that the protein exhibits KAT activity. More specifically, the disappearance of kynurenine indicates that the protein can catalyze the transamination of kynurenine to form kynurenic acid, and the disappearance of 3-hydroxykynurenine indicates that the protein can catalyze the transamination of 3-hydroxykynurenine to form xanthurenic acid. The production of kynurenic acid and / or xanthurenic acid can be confirmed by mass spectrometry.

[0030] Four KATs have been reported in mammals: kynurenine-oxoglutarate transaminase 1 (KAT I), kynurenine / alpha-aminoadipate aminotransferase (KAT II or AADAT), kynurenine-oxoglutarate transaminase 3 (KAT III) and mitochondrial aspartate aminotransferase (KAT IV). In the present invention, the kynurenine aminotransferase may be a human KAT or an orthologous protein. The term "ortholog" or "orthologous protein" as used herein refers to the functional counterpart (i.e., exhibiting KAT activity) of a protein in another species. Orthologous proteins are similar to each other because they are derived from a common ancestor. Thus, sequence differences between orthologs are the result of speciation. Orthologous sequences may be encompassed in longer or shorter isoforms. Methods for identifying orthologous proteins are well known in the art.

[0031] Human kynurenine-oxoglutarate transaminase 1 (KAT I) is encoded by the gene KYAT1, also named CCBL1 (Uniprot accession number: Q16773). Three isoforms of human KAT I are produced by alternative splicing: isoform 1 (SEQ ID NO: 1), isoform 2 (SEQ ID NO: 2) and isoform 3 (SEQ ID NO: 3).

[0032] Orthologous proteins of human KAT I may also be used in the present invention. Preferably, the orthologous proteins of human KAT I used in the present invention are mammalian proteins. Examples of orthologous proteins of human KAT I that can be used in the present invention include, but are not limited to, the orthologs listed in Table 1.

[0033] [Table 1]

[0034] Human kynurenine / alpha-aminoadipate aminotransferase (KAT II or AADAT) is encoded by the gene AADAT, also named KYAT2 or KAT2 (Uniprot accession number: Q8N5Z0). Two isoforms of human KAT II are produced by alternative splicing: isoform 1 (SEQ ID NO: 10) and isoform 2 (SEQ ID NO: 11).

[0035] Orthologous proteins of human KAT II may also be used in the present invention.Preferably, the orthologous proteins of human KAT II used in the present invention are mammalian proteins.Examples of orthologous proteins of human KAT II that can be used in the present invention include, but are not limited to, the orthologs listed in Table 2.

[0036] [Table 2]

[0037] Human kynurenine-oxoglutarate transaminase 3 (KAT III or CCBL2) is encoded by the gene KYAT3 (Uniprot accession number: Q6YP21). Three isoforms of human KAT III are produced by alternative splicing: isoform 1 (SEQ ID NO: 17), isoform 2 (SEQ ID NO: 18) and isoform 3 (SEQ ID NO: 19).

[0038] Orthologous proteins of human KAT III may also be used in the present invention.Preferably, the orthologous proteins of human KAT III used in the present invention are mammalian proteins.Examples of orthologous proteins of human KAT III that can be used in the present invention include, but are not limited to, the orthologs listed in Table 3.

[0039] [Table 3]

[0040] Human mitochondrial aspartate aminotransferase (KAT IV) is encoded by the gene GOT2, also named KYAT4 (Uniprot accession number: P00505). Two isoforms of human KAT IV are produced by alternative splicing: isoform 1 (SEQ ID NO: 26) and isoform 2 (SEQ ID NO: 27).

[0041] Orthologous proteins of human KAT IV may also be used in the present invention. Preferably, the orthologous proteins of human KAT IV used in the present invention are mammalian proteins. Examples of orthologous proteins of human KAT IV that can be used in the present invention include, but are not limited to, the orthologs listed in Table 4.

[0042] [Table 4]

[0043] In one embodiment, the kynurenine aminotransferase included in the composition or expressed by the recombinant bacterium is - human KAT I, human KAT II, ​​human KAT III, human KAT IV and their orthologues, and - a variant having at least 80% sequence identity to human KAT I, human KAT II, ​​human KAT III, human KAT IV, or to any ortholog thereof, and exhibiting KAT activity. may be selected from the group consisting of:

[0044] Preferably, the kynurenine aminotransferase contained in the composition or expressed by the recombinant bacterium is selected from the group consisting of KAT proteins of SEQ ID NOs: 1 to 32, and variants thereof having at least 80% sequence identity to any of SEQ ID NOs: 1 to 32 and exhibiting KAT activity.

[0045] The term "variant" as used herein refers to an enzyme derived from wild-type kynurenine aminotransferase, human kynurenine aminotransferase or its orthologues and containing modifications, i.e. substitutions, insertions, and / or deletions at one or more (e.g., several) positions. The term "deletion" used in reference to a position or amino acid means that an amino acid at a particular position is deleted or absent. The term "insertion" used in reference to a position or amino acid means that one or more amino acids are inserted or present adjacent to and immediately following the amino acid occupying the particular position. Variants can be obtained by various techniques well known in the art. In particular, examples of techniques for modifying a DNA sequence encoding a wild-type protein include, but are not limited to, site-directed mutagenesis, random mutagenesis, and synthetic oligonucleotide construction.

[0046] As used herein, the term "sequence identity" or "identity" refers to the number (%) of matches (identical amino acid residues) at positions from an alignment of two polypeptide sequences. Sequence identity is determined by comparing sequences when aligned to maximize overlap and identity while minimizing sequence gaps. In particular, sequence identity can be determined using any of several mathematical global or local alignment algorithms, depending on the length of the two sequences. Sequences of similar length are preferably aligned using a global alignment algorithm (e.g., the Needleman and Wunsch algorithm; Needleman and Wunsch, 1970), which optimally aligns sequences over their entire length, while sequences of significantly different lengths are preferably aligned using a local alignment algorithm (e.g., the Smith and Waterman algorithm (Smith and Waterman, 1981) or the Altschul algorithm (Altschul et al., 1997; Altschul et al., 2005)). Alignment for purposes of determining percent amino acid sequence identity can be accomplished in a variety of ways that are within the skill in the art, for example, using publicly available computer software available at Internet websites such as http: / / blast.ncbi.nlm.nih.gov / or http: / / www.ebi.ac.uk / Tools / emboss / . Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full length of the sequences to be compared.Preferably, for purposes herein, % amino acid sequence identity values ​​refer to values ​​generated using a local alignment algorithm, preferably the Basic Local Alignment Search Tool (BLAST), which finds regions of local similarity between sequences and calculates the statistical significance of matches, with all search parameters set to default values, i.e., blastp algorithm, Expect threshold=0.05, word size=3, Scoring matrix=BLOSUM62, Gap costs: existence=11, extension=1, Conditional compositional score matrix adjustment.

[0047] In another embodiment, the kynurenine aminotransferase included in the composition or expressed by the recombinant bacterium is - human KAT II, ​​human KAT III, human KAT IV and their orthologues, and - a variant having at least 80% sequence identity to human KAT II, ​​human KAT III, human KAT IV, or any ortholog thereof, and exhibiting KAT activity. is selected from the group consisting of:

[0048] Preferably, the kynurenine aminotransferase contained in the composition or expressed by the recombinant bacterium is selected from the group consisting of KAT proteins of SEQ ID NOs: 10 to 32, and variants thereof having at least 80% sequence identity to any of SEQ ID NOs: 10 to 32 and exhibiting KAT activity.

[0049] In a preferred embodiment, the kynurenine aminotransferase comprised in the composition or expressed by the recombinant bacterium is - human KAT II and its orthologues, and - a variant having at least 80% sequence identity to human KAT II or to any ortholog thereof and exhibiting KAT activity. is selected from the group consisting of:

[0050] Preferably, the kynurenine aminotransferase contained in the composition or expressed by the recombinant bacterium is selected from the group consisting of KAT proteins of SEQ ID NOs: 10 to 16, and variants thereof having at least 80% sequence identity to any of SEQ ID NOs: 10 to 16 and exhibiting KAT activity.

[0051] In some embodiments, the kynurenine aminotransferase contained in the composition or expressed by the recombinant bacterium can be fused at its N-terminus and / or C-terminus to another polypeptide to create a hybrid or fusion polypeptide. Techniques for producing fusion polypeptides are known in the art and include ligating a coding sequence encoding a variant and an additional region of another polypeptide such that they are in frame and expression of the fusion polypeptide is under the control of the same promoter and terminator. The additional region of the fusion polypeptide can be selected to enhance the stability of the enzyme, to facilitate secretion of the fusion protein from a cell (such as a bacterial cell) (such as an N-terminal hydrophobic signal peptide), or to assist in the purification of the fusion protein. More specifically, the additional region can be a tag useful for purification or immobilization of the enzyme. Such tags are well known to those skilled in the art, for example His-tag (His6), FLAG-tag, HA-tag (epitope derived from influenza protein hemagglutinin), maltose-binding protein (MPB), MYC-tag (epitope derived from human proto-oncoprotein MYC) or GST-tag (small glutathione-S-transferase). The fusion polypeptide may further comprise a cleavage site for a protease or chemical agent between the enzyme and the additional region. When the fusion protein is secreted, the site is cleaved to release two separate polypeptides. The kynurenine aminotransferase may be fused at its N-terminus and / or C-terminus to one or more polypeptides exhibiting a distinct enzymatic activity. Optionally, it may be modified (e.g. chemically, enzymatically, physically, etc.) to improve one of its characteristics, such as stability or activity.

[0052] In some embodiments, the compositions used in the present invention comprise a protein that exhibits kynurenine aminotransferase, ie, KAT activity, and is as defined above.

[0053] Said kynurenine aminotransferase can be produced by known methods, such as recombinant techniques. In particular, it can be expressed and secreted, isolated or purified from a host cell, preferably a recombinant bacterium, as defined below or as illustrated in the examples. As used herein, the term "host cell" means any cell type that is susceptible to transformation, transfection, transduction, or the like, with a nucleic acid construct or expression vector comprising a polynucleotide encoding a kynurenine aminotransferase as used in the present invention, and that can express said enzyme.

[0054] In particular, said kynurenine aminotransferase may be produced by a method comprising: (a) culturing a host cell, in particular a recombinant bacterium as defined below, in a suitable culture medium under suitable conditions for expressing said kynurenine aminotransferase; and (b) recovering said kynurenine aminotransferase from said cell culture.

[0055] The host cells are cultured in a suitable nutrient medium for producing the polypeptide, using methods known in the art. For example, the cells can be cultured in a suitable medium and under conditions that allow the enzyme to be expressed and / or isolated, in shake flask cultures, or in small- or large-scale fermentation (including continuous, batch, fed-batch, or solid-state fermentation) in laboratory or industrial fermenters. The culture is carried out in a suitable nutrient medium containing carbon and nitrogen sources and inorganic salts, using procedures known in the art. Suitable media are available from commercial suppliers or can be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection).

[0056] The enzyme can be recovered using any method known in the art. For example, the enzyme can be recovered from the nutrient medium by conventional procedures including, but not limited to, collection, centrifugation, filtration, extraction, spray drying, evaporation, or precipitation. Optionally, the enzyme can be partially or completely purified by various procedures known in the art including, but not limited to, chromatography (e.g., ion exchange, affinity, hydrophobic, chromatofocusing, and size exclusion), electrophoretic procedures (e.g., preparative isoelectric focusing), differential solubility (e.g., ammonium sulfate precipitation), SDS-PAGE, or extraction to obtain a substantially pure polypeptide. Preferably, the enzyme is secreted into the nutrient medium and can be directly recovered from the culture supernatant before being isolated or purified.

[0057] In embodiments in which the composition comprises a kynurenine aminotransferase, the kynurenine aminotransferase is preferably in isolated or purified form.

[0058] As used herein, the term "isolated" with respect to a polypeptide refers to a polypeptide that has been separated from at least one associated substance found in the source material (e.g., separated from at least one other cellular component) or any material associated with the protein in any process used to produce the preparation. For example, an isolated polypeptide is typically devoid of at least some proteins or other components of cells, e.g., recombinant cells, with which it is normally associated or with which it is normally mixed or in solution.

[0059] As used herein, the term "purified" means that the protein is essentially free from other proteins, such as, for example, a product purified from a culture of recombinant host cells or a product purified from a non-recombinant source. The term "purified" does not require absolute purity, but rather is intended as a relative definition. It refers to a protein that is essentially free of other components as determined by analytical techniques well known in the art (e.g., a purified protein forms a distinct band in an electrophoretic gel, a chromatographic eluent, and / or a medium subjected to density gradient centrifugation). A purified protein is at least 50 percent pure, and usually at least 75, 80, 85, 90, 95, 96, 97, 98, 99 percent pure (e.g., percent by mass on a molar basis).

[0060] The kynurenine aminotransferase can be administered in its mature form or in its precursor form.

[0061] The KAT used in the present invention, particularly contained in the composition, may be modified in various ways. For example, one or more amino acids in the L-configuration may be replaced by amino acids in the D-configuration. The polypeptide may be post-translationally modified and / or further chemically modified, particularly glycosylated, amidated, acylated, acetylated or methylated. Protective groups may be added to the C-terminus and / or N-terminus. For example, the protective group at the N-terminus may be acylated or acetylated, and the protective group at the C-terminus may be amidated or esterified. The polypeptide may contain pseudopeptide bonds that confer increased resistance to peptidases, such as CHOH-CH2, NHCO, CH2-O, CH2CH2, CO-CH2, NN, CH=CH, CH2NH, and CH2-S, instead of the "traditional" CONH peptide bonds. One or more amino acids may be replaced with rare amino acids, in particular hydroxyproline, hydroxylysine, allohydroxylysine, 6-N-methyllysine, N-ethylglycine, N-methylglycine, N-ethylasparagine, allo-isoleucine, N-methylisoleucine, N-methylvaline, pyroglutamine and aminobutyric acid; or synthetic amino acids, in particular ornithine, norleucine, norvaline and cyclohexylalanine.

[0062] The present invention also covers the use of pharma- ceutically acceptable salts of such polypeptides. Pharmaceutically acceptable salts may be salts with pharma- ceutically acceptable inorganic acids, such as, for example, hydrochloric acid, hydrobromic acid, sulfuric acid, and phosphoric acid, salts with pharma- ceutically acceptable organic acids, such as, for example, acetic acid, citric acid, maleic acid, malic acid, succinic acid, ascorbic acid, and tartaric acid, salts with pharma- ceutically acceptable inorganic bases, such as sodium, potassium, calcium, magnesium, or ammonium salts, or salts with organic bases having a salt-forming nitrogen, as commonly used in the pharmaceutical arts. Methods for preparing these salts are well known to those skilled in the art.

[0063] The composition used in the present invention may comprise one or several KAT enzymes, i.e. (i) - human KAT I, human KAT II, ​​human KAT III, human KAT IV and their orthologues, and - a variant having at least 80% sequence identity to human KAT I, human KAT II, ​​human KAT III, human KAT IV, or to any ortholog thereof, and exhibiting KAT activity; or (ii) - human KAT II, ​​human KAT III, human KAT IV and their orthologues, and - a variant having at least 80% sequence identity to human KAT II, ​​human KAT III, human KAT IV, or any ortholog thereof, and exhibiting KAT activity. or (iii) - human KAT II and its orthologues, and - a variant having at least 80% sequence identity to human KAT II or to any ortholog thereof and exhibiting KAT activity. The protein may comprise one or several KAT enzymes selected from the group consisting of:

[0064] Preferably, the pharmaceutical composition used in the present invention comprises: - human KAT II and its orthologues, and - a variant having at least 80% sequence identity to human KAT II or to any ortholog thereof and exhibiting KAT activity. The protein comprises one or several KAT enzymes selected from the group consisting of:

[0065] In some embodiments, the compositions used in the present invention comprise recombinant bacteria that exhibit kynurenine aminotransferase, i.e., KAT activity, and that have been genetically modified to express and secrete a protein as defined above.

[0066] As used herein, the term "recombinant bacterium" or "genetically modified bacterium" refers to a bacterium that contains a genome not found in nature and that has been modified as a result of either the deletion, insertion or modification of genetic elements thereof. In particular, this term refers to a bacterium that comprises a heterologous nucleic acid, expression cassette or vector as described below, i.e. a nucleic acid, cassette or vector that does not naturally occur in said bacterium.

[0067] As used herein, the term "endogenous" with respect to a bacterium refers to a genetic element or protein that is naturally present in said bacterium. The term "heterologous" with respect to a bacterium refers to a genetic element or protein that is not naturally present in said bacterium.

[0068] The recombinant bacteria used in the present invention are genetically modified by introducing a heterologous expression cassette or vector comprising a nucleic acid encoding a KAT enzyme as defined above.

[0069] The nucleic acid encoding the KAT enzyme can be derived from the sequence of the protein and the codon usage can be adapted according to the bacterium in which the nucleic acid is transcribed. These steps can be carried out by methods well known to those skilled in the art, some of which are described in the reference manual Sambrook et al. (Sambrook J, Russell D (2001) Molecular cloning: a laboratory manual, Third Edition Cold Spring Harbor).

[0070] As used herein, an expression cassette comprises a nucleic acid encoding a KAT enzyme as defined above, operably linked to one or more control sequences that direct expression of the nucleic acid in a recombinant bacterium under conditions compatible with the control sequences.

[0071] The control sequence may include a promoter recognized by the recombinant bacterium. The promoter contains a transcriptional control sequence that mediates the expression of the KAT enzyme. The promoter may be any polynucleotide that exhibits transcriptional activity in the recombinant bacterium, including mutant, truncated, and hybrid promoters, and may be derived from a gene encoding an extracellular or intracellular polypeptide, either homologous or heterologous to the bacterium. The promoter may be a strong, weak, constitutive, or inducible promoter. Usually, the promoter is heterologous to the nucleic acid encoding the KAT enzyme, i.e., it is not originally operably linked to said nucleic acid, or it is originally operably linked to said nucleic acid at another location. The promoter should be selected to exhibit transcriptional activity in the recombinant bacterium.

[0072] Examples of suitable promoters include, but are not limited to, constitutive promoters such as P21, P23, P32, P44 or P59 (Morello et al., J Mol Microbiol Biotechnol 2008;14:48-58) or inducible promoters such as the nisin-inducible controlled gene expression (NICE) system obtained from the nis(nisABTCIPRKEFG) operon present in some Lactococcus lactis strains (Kuipers et al., J Biotechnol 1998;64:15-21).

[0073] The control sequence may be a transcription terminator recognized by bacteria to terminate transcription. The terminator is operably linked to the 3' end of the nucleic acid encoding the KAT enzyme. Any terminator that is functional in bacteria can be used in the present invention. Usually, the terminator is selected in relation to the promoter. Examples of suitable terminators include, but are not limited to, the rho-independent transcription terminator trpA (Christie et al., 1981, Proc. Natl. Acad. Sci. USA 78:4180-4184), the terminal region of the rrnB gene encoding ribosomal RNA in E. coli (Orosz et al. Eur J Biochem. 1991 Nov 1;201(3):653-9).

[0074] The control sequence may be a signal peptide coding sequence that encodes a signal peptide linked to the N-terminus of the encoded polypeptide and directs the polypeptide into the secretory pathway of the cell, i.e., for secretion into the extracellular (or periplasmic) space. Any signal peptide coding sequence that directs the expressed polypeptide into the bacterial secretory pathway may be used. The signal peptide coding sequence can be cleaved by a number of signal peptidases to remove it from the remainder of the expressed polypeptide. Examples of effective signal peptide coding sequences for bacterial host cells include, but are not limited to, the signal peptide of Usp45 (SPUsp45), the major Sec-dependent protein secreted by Lactococcus lactis (Borrero et al., 2011. Applied Microbiology and Biotechnology 89(1):131-43), signal peptide SP310 (Ravn et al. Microbiology (Reading). 2003 Aug;149(Pt 8):2193-2201), and signal peptide Exp4 (U.S. Patent Application No. US2006199246). It may be desirable to add regulatory sequences that regulate the expression of the KAT enzyme relative to the growth of the recombinant bacteria. Examples of regulatory systems are those that turn expression of a gene on or off in response to a chemical or physical stimulus, including the presence of a regulatory compound. Regulatory systems in prokaryotic systems include the lac, tac, and trp operator systems.

[0075] Typically, the expression cassette comprises or consists of a nucleic acid encoding a KAT enzyme operably linked to a transcription promoter and a transcription terminator. The expression cassette may comprise several nucleic acids encoding several KAT enzymes operably linked to a transcription promoter and a transcription terminator. Preferably, the expression cassette further comprises a signal peptide coding sequence that provides for secretion of the KAT enzyme into the extracellular space.

[0076] The expression cassette may be used as is to transform bacteria or may be introduced into an expression vector and said vector may be used to transform bacteria.

[0077] The choice of vector will typically depend on the compatibility of the vector with the bacterium into which it is to be introduced. The vector may be an autonomously replicating vector, i.e. a vector that exists as an extrachromosomal entity and whose replication is independent of chromosomal replication, such as a plasmid, an extrachromosomal element, a minichromosome, or an artificial chromosome. The vector may contain any means for ensuring self-replication. Alternatively, the vector may be one that, when introduced into the bacterium, is integrated into the genome and replicates together with the chromosome into which it is integrated.

[0078] The vector preferably contains one or more selectable markers that allow for easy selection of bacteria containing the vector. A selectable marker is a gene whose product confers insecticide or viral resistance, resistance to heavy metals, prototrophy to auxotrophs, and the like. Examples of bacterial selectable markers include, but are not limited to, markers that confer antibiotic resistance, such as ampicillin, chloramphenicol, kanamycin, neomycin, spectinomycin, or tetracycline resistance.

[0079] The vector preferably contains elements that allow the integration of the vector into the bacterial genome or the autonomous replication of the vector in the cell independent of the genome. In the case of integration into the host cell genome, the integration of the sequence into the genome can rely on homologous or non-homologous recombination. On the one hand, the vector may contain additional polynucleotides to direct integration by homologous recombination into the genome of the host cell at a precise location. These additional polynucleotides may be any sequence that is homologous to the target sequence in the genome of the host cell. On the other hand, the vector may be integrated into the genome of the host cell by non-homologous recombination.

[0080] In autonomous replication, the vector may further comprise an origin of replication that allows the vector to replicate autonomously in the relevant bacterium. The origin of replication may be any plasmid replicator that mediates autonomous replication that functions in cells. The term "origin of replication" or "plasmid replicator" refers to a polynucleotide that allows a plasmid or vector to replicate in vivo. Examples of bacterial origins of replication include, but are not limited to, the origins of replication of plasmids pBR322, pUC19, pACYC177, and pACYC184 that allow replication in E. coli, and pUB1 10, pE194, pTA1060, and pAMβ1 that allow replication in Bacillus.

[0081] Methods for the selection of factors depending on the bacteria in which expression is desired are well known to those skilled in the art. The vectors can be constructed by classical techniques of molecular biology well known to those skilled in the art.

[0082] The recombinant bacterium used in the present invention can be obtained by introducing an expression cassette or vector as described above, so that the cassette or vector is maintained as a chromosomal integrant or as a self-replicating extrachromosomal vector. The introduction of the expression cassette or vector into the bacterium can be carried out using any method known to those skilled in the art. Preferably, at least the expression cassette or a part thereof, including the nucleic acid encoding the KAT enzyme and allowing the expression of the nucleic acid, is integrated into the genome of the bacterium.

[0083] The recombinant bacteria contained in the composition used in the present invention are live bacteria. The bacteria may be a Live Biotherapeutic Product (LBP), i.e., a living organism designed and developed to treat, cure, or prevent a disease or condition in a subject. It should be understood that in a "live bacterium," the cellular integrity is maintained and that cellular processes occur or can occur when the bacterium is cultured in suitable medium and conditions. The live bacteria can be replated in a suitable culture medium and grown under suitable conditions. The live bacteria can be preserved by freezing in liquid nitrogen, stepwise freezing or lyophilization and then storage at temperatures preferably ranging from +4°C to -80°C prior to administration.

[0084] The recombinant bacterium may be any bacterium that can be administered to a subject without inducing disease (non-pathogenic bacteria) and has a metabolism adapted to the gastrointestinal environment. The recombinant bacterium may be genetically engineered to improve its pharmacokinetic and pharmacodynamic properties. For example, the bacterium may be modified to exhibit auxotrophy to limit bacterial replication in the absence of supplied metabolic products. Examples and strategies for developing chassis organisms for engineered live bacterial therapeutics have been recently reviewed (Charbonneau et al. 2020, Nature Communications volume 11, Article number: 1738), and the skilled artisan can easily select a bacterial chassis adapted for use in the present invention.

[0085] In particular, the recombinant bacterium may be selected from the group consisting of the genus Allobaculum (e.g., Allobaculum stercoricanis), the genus Akkermansia (e.g., Akkermansia muciniphila), the genus Anaerostipes (e.g., Anaerostipes hadrus, Anaerostipes caccae, and Anaerostipes butyraticus), the genus Bifidobacterium, the genus Bacillus (e.g., Bacillus subtilis and Bacillus clausii), the genus Bacillus subtilis (e.g., Bacillus subtilis), and the genus Bacillus subtilis (e.g., Bacillus subtilis). clausii), Propionibacterium, Bacteroides, Eubacterium, Enterococcus, Ruminococcus (e.g. Ruminococcus gnavus), Roseburia (e.g. Roseburia hominis) and Faecalibacterium (e.g. Faecalibacterium prausnitzii), Escherichia coli, and lactic acid bacteria, in particular the Lactobacillus genus (e.g. Lactobacillus casei, Lactobacillus reuteri, Lactobacillus plantarum). plantarum, Lactobacillus taiwanensis, Lactobacillus johnsonii, Lactobacillus animalis, Lactobacillus murinus, Lactobacillus salivarius, Lactobacillus gasseri, Lactobacillus bulgaricusbulgaricus, and Lactobacillus delbrueckii subsp. bulgaricus, lactic acid bacteria belonging to the genus Lactococcus (e.g., Lactococcus lactis) and the genus Streptococcus (e.g., Streptococcus thermophilus). Preferably, the recombinant bacterium is selected from bacteria belonging to the genus Lactobacillus and Lactococcus, in particular from the group consisting of Lactobacillus casei and Lactococcus lactis.

[0086] In some other embodiments, the compositions used in the present invention comprise xanthurenic acid, a derivative thereof, or any pharma- ceutically acceptable salt or solvate thereof.

[0087] In one embodiment, the xanthurenic acid derivative is of formula (I):

[0088] [ka]

[0089] [In the formula, R1, R2 and R3 each represent a hydrogen atom, a hydroxyl group, a halogen atom, a -CO-R8 group or a -CO2R8 group (R8 is H or C 1~10 alkyl group), -NR9R 9' (R9 and R 9' are independently a hydrogen atom or C 1~10 alkyl group), nitro group, cyano group, or C optionally substituted with a halogen atom 1~10 Alkyl, C 2~10 Alkenyl or C 2~10 C optionally substituted with an alkynyl group and a halogen atom 1~10 independently selected from the group consisting of alkyloxy; R4 and R6 are each a hydrogen atom, and C 1~10 independently selected from the group consisting of alkyl groups; R5 is a hydroxyl group, a hydrogen atom, -NR7R 7' (R7 and R 7' are independently a hydrogen atom or C 1~10 alkyl group), C 1~10 Alkyl groups, and C 1~10 alkoxy groups] or a tautomeric form thereof.

[0090] In one particular embodiment, the xanthurenic acid derivative is R1, R2 and R3 are a hydrogen atom, a hydroxyl group, a halogen atom, or a C group optionally substituted by a halogen atom. 1~10 Alkyl, C 2~10 Alkenyl or C 2~10 alkynyl groups; R4 and R6 are hydrogen atoms and C 1~10 independently selected from the group consisting of alkyl groups; R5 is a hydroxyl group, -NR7R 7' (R7 and R 7' are independently a hydrogen atom or C 1~10 alkyl group), C 1~10 Alkyl groups, and C 1~10 alkoxy groups, of formula (I) or a tautomeric form thereof:

[0091] In another particular embodiment, the xanthurenic acid derivative is R1, R2 and R3 are a hydrogen atom, a hydroxyl group, a halogen atom, or a C group optionally substituted by a halogen atom. 1~6 Alkyl, C 2~6 Alkenyl or C 2~6 alkynyl groups; R4 and R6 are hydrogen atoms and C 1~6 independently selected from the group consisting of alkyl groups; R5 is a hydroxyl group, -NR7R 7' (R7 and R 7' are independently a hydrogen atom or C 1~6 alkyl group), C 1~6Alkyl groups, and C 1~6 alkoxy groups, of formula (I) or a tautomeric form thereof:

[0092] In another particular embodiment, the xanthurenic acid derivative is R1, R2 and R3 are a hydrogen atom, an oxygen atom, a halogen atom, or a C 1~10 Alkyl, C 2~10 Alkenyl or C 2~10 alkynyl groups; R4 and R6 are hydrogen atoms and C 1~10 alkyl groups, or R4 and / or R6 are absent; R5 is a hydroxyl group, NHR7, NR7R7, or C 1~10 alkyl or alkoxy groups, where R7 is a hydrogen atom or 1~10 alkyl groups), It is of formula (I).

[0093] In another particular embodiment, the xanthurenic acid derivative is R1, R2 and R3 are a hydrogen atom, an oxygen atom, a halogen atom, or a C 1~6 Alkyl, C 2~6 Alkenyl or C 2~6 alkynyl groups; R4 and R6 are hydrogen atoms and C 1~6 alkyl groups, or R4 and / or R6 are absent; R5 is a hydroxyl group, NHR7, NR7R7, or C 1~6 Alkyl or alkoxy group (R7 is a hydrogen atom and C 1~6 alkyl groups; It is of formula (I).

[0094] For example, C1~C 10, C1 to C6 or C2 to C 10 Terms described herein with a prefix such as C1-C9, C1-C5, or C2-C9 can also be used with a fewer number of carbon atoms, such as C1-C9, C1-C5, or C2-C9. 10 When the term C1-C6 is used, this means that the corresponding hydrocarbon chain may contain 1 to 10 carbon atoms, in particular 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms. For example, when the term C1-C6 is used, this means that the corresponding hydrocarbon chain may contain 1 to 6 carbon atoms, in particular 1, 2, 3, 4, 5, or 6 carbon atoms. For example, when the term C2-C6 is used, this means that the corresponding hydrocarbon chain may contain 2 to 6 carbon atoms, in particular 2, 3, 4, 5, or 6 carbon atoms.

[0095] As used herein, the term "alkyl" refers to a monovalent radical containing only carbon and hydrogen atoms arranged in a straight or branched chain. (C1-C3)-alkyl groups include methyl, ethyl, propyl, or isopropyl. Preferably, the (C1-C3)-alkyl group is methyl or ethyl, more preferably methyl. (C1-C6)-alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, or hexyl.

[0096] As used herein, the term "alkenyl" refers to an unsaturated straight-chain or branched aliphatic group containing at least one carbon-carbon double bond. The term "(C2-C6)alkenyl" more specifically means ethenyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, or hexenyl.

[0097] The term "alkynyl" refers to an unsaturated straight-chain or branched aliphatic group containing at least one carbon-carbon triple bond. The term "(C2-C6)alkynyl" more specifically means ethynyl, propynyl, butynyl, pentynyl, isopentynyl, or hexynyl.

[0098] The term "halogen" corresponds to a fluorine, chlorine, bromine or iodine atom.

[0099] Examples of xanthurenic acid derivatives include, but are not limited to, oxo-xanthurenic acid (OXA) and di-oxo-xanthurenic acid (DOXA).

[0100] [Table 5]

[0101] In a preferred embodiment, the composition comprises xanthurenic acid or any pharma- ceutically acceptable salt or solvate thereof.

[0102] Xanthurenic acid is of the formula (II)

[0103] [ka]

[0104] It is.

[0105] It will be apparent to one skilled in the art that certain compounds described in this disclosure may exist in tautomeric forms, and all such tautomeric forms of the compounds are within the scope of this disclosure. Specifically, the term "xanthurenic acid" includes compounds of formula (II) and their tautomeric forms, such as compounds of formulas (III) and (IV).

[0106] [ka]

[0107] Pharmaceutically acceptable salts of xanthurenic acid or its derivatives are salts that are non-toxic to patients and suitable for maintaining the stability of the compound to enable delivery of the compound to target cells or tissues. Pharmaceutically acceptable salts are well known in the art. More specifically, "pharmaceutical salts" include inorganic and even organic acid salts. Representative examples of suitable inorganic acids include hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, and the like. Representative examples of suitable organic acids include formic acid, acetic acid, trichloroacetic acid, trifluoroacetic acid, propionic acid, benzoic acid, cinnamic acid, citric acid, fumaric acid, maleic acid, methanesulfonic acid, and the like. Further examples of pharmaceutical inorganic or organic acid addition salts include pharmaceutical salts listed in J. Pharm. Sci. 1977, 66, 2 and Handbook of Pharmaceutical Salts: Properties, Selection, and Use, edited by P. Heinrich Stahl and Camille G., Wermuth 2002. "Pharmaceutical salt" also includes inorganic and even organic base salts. Representative examples of suitable inorganic bases include sodium or potassium salts, alkaline earth metal salts, such as calcium or magnesium salts, or ammonium salts. Representative examples of suitable salts with organic bases include, for example, salts with methylamine, dimethylamine, trimethylamine, piperidine, morpholine or tris-(2-hydroxyethyl)amine.

[0108] As used herein, the term "solvate" refers to a solvent addition form that contains stoichiometric or non-stoichiometric amounts of solvent. Some compounds have the tendency to trap a fixed molar ratio of solvent molecules in the crystalline solid state to form a solvate. If the solvent is water, the solvate that is formed is a hydrate. If the solvent is alcohol, the solvate that is formed is an alcoholate. A hydrate is formed by the combination of one or more water molecules with one of the substances in which water retains its molecular state as H2O, and such a combination can form one or more hydrates.

[0109] The composition used in the present invention may be a pharmaceutical composition, a food composition or a food supplement.

[0110] In embodiments in which the composition is a pharmaceutical composition, the active compounds as defined above, i.e. kynurenine aminotransferase, live recombinant bacteria that have been genetically modified to express and secrete said kynurenine aminotransferase, and / or xanthurenic acid or a derivative thereof, or any pharma- ceutically acceptable salt or solvate thereof, may be combined with pharma- ceutically acceptable excipients, and optionally a sustained release matrix, such as a biodegradable polymer, to form a therapeutic composition.

[0111] "Pharmaceutically" or "pharmacologically acceptable" refers to molecular entities and compositions that do not produce adverse allergic or other untoward reactions when administered to a mammal, particularly a human, as appropriate. A pharmaceutically acceptable carrier or excipient refers to any type of non-toxic solid, semi-solid or liquid filler, diluent, encapsulating material or formulation aid. Pharmaceutically acceptable excipients that may be used in the compositions according to the invention are well known to those skilled in the art and may vary according to the disease to be treated and the route of administration.

[0112] The composition used in the present invention can be administered by any suitable method for placing it in the digestive tract, preferably the small intestine and / or colon, of the subject to be treated.In particular, the composition can be administered by enteral or parenteral route, preferably by oral, sublingual, subcutaneous, intramuscular, intravenous, transdermal, topical or rectal administration route.Preferably, the composition is administered or adapted for administration by rectal or oral route.

[0113] In particular, in some embodiments where the composition comprises kynurenine aminotransferase and / or xanthurenic acid or a derivative thereof, the composition is preferably administered by oral, rectal, subcutaneous or intravenous routes, and in some other embodiments where the composition comprises live recombinant bacteria, the composition is preferably administered by oral or rectal routes.

[0114] In one embodiment, the pharmaceutical composition can be administered by oral route. For oral administration, the pharmaceutical composition can be formulated into conventional oral dosage forms such as tablets, capsules, powders, granules, and liquid preparations such as syrups, elixirs, and concentrated drops. Non-toxic solid carriers or diluents may be used, including, for example, pharmaceutical grades of mannitol, lactose, starch, magnesium stearate, sodium saccharin, talc, cellulose, glucose, sucrose, magnesium, carbonates, and the like. Compressed tablets also require binders, which are agents that impart cohesiveness to the powdered material. For example, starch, gelatin, sugars such as lactose or dextrose, and natural or synthetic gums can be used as binders. Disintegrants may also be required in the tablet to facilitate the breakup of the tablet. Disintegrants include starch, clay, cellulose, algins, gums, and cross-linked polymers. In addition, lubricants and glidants may also be included in the tablet to prevent adhesion of tablet material to surfaces during the manufacturing process and improve the flow properties of the powdered material during manufacture. Colloidal silicon dioxide is most commonly used as a flow enhancer, and compounds such as talc or stearic acid are most commonly used as lubricants.Well-known thickening agents may be added to the composition, such as corn starch, agar, natural or synthetic gums, resins, methylcellulose, sodium carboxymethylcellulose, guar, xanthan, and the like.Preservatives may be included in the composition, including methylparaben, propylparaben, benzyl alcohol, and ethylenediaminetetraacetate.

[0115] Preferably, for oral administration, the composition is in a gastroresistant oral form that allows the active compound contained in the composition to pass through the stomach and be released in the small intestine. Substances that can be used in enteric coating include, for example, alginic acid, cellulose acetate phthalate, plastics, waxes, shellac, and fatty acids (e.g., stearic acid or palmitic acid).

[0116] In another embodiment, the pharmaceutical composition can be administered by rectal route.Suitable rectal route forms include, but are not limited to, suppositories and enemas.In particular, the active compound can be incorporated into any of the known suppository bases by methods known in the art.Examples of such bases include cocoa butter, polyethylene glycol (carbowax), polyethylene sorbitan monostearate, and mixtures thereof with other compatible substances for adjusting melting point or dissolution rate.

[0117] The compositions used in the present invention can be formulated to release the active compound substantially immediately upon administration, or at any predetermined time or period after administration.

[0118] The pharmaceutical compositions used in the present invention may be used in combination with or may further comprise at least one additional active ingredient, in particular at least one bacterial probiotic and / or at least one prebiotic and / or at least one drug useful in the treatment of inflammatory bowel disease.

[0119] The term "bacterial probiotics" has its general meaning in the art and refers to useful bacteria that can have a beneficial effect on the health of the host, i.e., are applicable in the prevention, treatment or cure of a disease or condition in the host, preferably a human. The term may refer to killed or live bacteria. Preferably, the term refers to live bacteria (also named live biologicals). Preferably, said bacterial probiotics exhibit anti-inflammatory activity. Such bacterial probiotics include, for example, species of the genera Allobaculum (e.g., Allobaculum stercolicanis), Akkermansia (e.g., Akkermansia muciniphila), Anaerostipes (e.g., Anaerostipes hadras, Anaerostipes cacae, and Anaerostipes butyraticus), Bifidobacterium, Bacillus (e.g., Bacillus subtilis and Bacillus clausii), Propionibacterium, Bacteroides, Eubacterium, Enterococcus, Ruminococcus (e.g., Ruminococcus gnavus), Roseburia (e.g., Roseburia hominis), and Faecaliba. The bacteria may be selected from the group consisting of bacteria belonging to the genus Lactobacillus (e.g., Faecalibacterium prausnitzii), Escherichia coli, and lactic acid bacteria, in particular lactic acid bacteria belonging to the genus Lactobacillus (e.g., Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus taiwanensis, Lactobacillus johnsonii, Lactobacillus animalis, Lactobacillus murinus, Lactobacillus salivarius, Lactobacillus gasseri, Lactobacillus bulgaricus, and Lactobacillus delbrueckii subsp. bulgaricus), the genus Lactococcus, and the genus Streptococcus (e.g., Streptococcus thermophilus).

[0120] As used herein, "prebiotic" refers to an ingredient that can induce certain changes in both the composition and / or activity of the administered probiotic and / or the gut microbiota, resulting in benefits to the host. Preferably, said prebiotic can be degraded by the probiotic, increasing the shelf life of said probiotic after administration to a patient. Examples of prebiotics include, but are not limited to, complex carbohydrates, polyphenols, amino acids, peptides, minerals, or other nutritional components that are essential for the survival of probiotics. In particular, the prebiotic can be selected from the group consisting of inulin, inositol, tagatose, lactulose, alpha-glucan oligosaccharides, trans-galacto-oligosaccharides (TOS), fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), xylo-oligosaccharides (XOS), and mixtures thereof.

[0121] Examples of drugs useful in the treatment of inflammatory bowel disease include, but are not limited to, corticosteroids, 5-aminosalicylates, immunosuppressants such as cyclosporine, azathioprine, 6-mercaptopurine, methotrexate, anti-TNF drugs (such as infliximab, adalimumab, golimumab, certolizumab, etc.), anti-integrin drugs (such as natalizumab, vedolizumab, etc.), anti-IL12 and / or IL23 antibodies (such as ustekinumab), JAK inhibitors (such as tofacitinib), antibiotics, anti-diarrheal drugs, analgesics, iron supplements, vitamin B-12, calcium, and vitamin D.

[0122] In another embodiment, the composition may be a food composition or a food supplement.

[0123] By "food composition" is meant any composition that contains food ingredients such as macronutrients, micronutrients, vitamins and / or minerals. Food compositions may be intended for human or animal consumption and may be liquid, pasty or solid. Examples of food compositions include, but are not limited to, dairy products such as cheese, butter, cream, yogurt, cultured milk, ice cream, cooked products such as bread, biscuits and cakes, fruit products such as fruit juice, fruit compote or fruit paste, soy food products, starch-based food products, edible oil compositions, spreads, breakfast cereals, infant formulas, food bars (e.g. cereal bars, breakfast bars, energy bars, nutrition bars), chewing gum, beverages, drinking supplements (powders added to beverages).

[0124] As used herein, the term "food supplement" refers to any composition that is formulated and administered separately from other foods to supplement the nutritional intake of a subject, i.e., a human or animal. The supplement may be in any suitable form known to those skilled in the art, preferably in the form of a dietary food or oral supplement.

[0125] In certain embodiments, the pharmaceutical composition, food composition or food supplement may further comprise or be used in combination with nicotinamide adenine dinucleotide (NAD) or its precursor. NAD may be administered in oxidized (NAD+) or reduced (NADH) form. Examples of NAD precursors include, but are not limited to, nicotinamide (NAM), nicotinic acid (NA), nicotinamide mononucleotide (NMN), and nicotinamide riboside (NR).

[0126] Preferably, in these embodiments, the pharmaceutical composition, food composition or food supplement comprises a KAT enzyme.

[0127] Preferably, the nicotinamide adenine dinucleotide or its precursor is administered by oral or intravenous route. Depending on the nature of the composition and the route of administration, the nicotinamide adenine dinucleotide or its precursor and the composition can be administered simultaneously or separately, via the same route or via different routes.

[0128] The composition as described above is used in the treatment of inflammatory bowel disease.The present invention also relates to the use of the composition as described above for the manufacture of a medicament for treating inflammatory bowel disease.The present invention further relates to a method for treating inflammatory bowel disease in a subject, comprising administering to the subject a composition as described above.

[0129] As used herein, the terms "treatment", "treat" or "treating" refer to any action intended to improve the health status of a patient, such as the cure, prevention, prophylaxis and delay of disease. In certain embodiments, such terms refer to the amelioration or eradication of a disease or symptoms associated therewith. In other embodiments, the terms refer to the minimization of the spread or worsening of a disease resulting from the administration of one or more therapeutic agents, e.g., a composition of the invention, to a subject having such a disease.

[0130] As used herein, "inflammatory bowel disease" or "IBD" refers to any of a variety of diseases characterized by inflammation of all or part of the small intestine. Examples of inflammatory bowel diseases include, but are not limited to, Crohn's disease (such as enteritis, ileitis, colitis, ileocolitis, gastroduodenal and perianal Crohn's disease), ulcerative colitis (such as ulcerative colitis, ulcerative ileocolitis, ulcerative proctitis, ulcerative proctosigmoiditis, pseudopolyposis of the colon, mucosal proctocolitis, and left-sided or pancolitis ulcerative colitis), indeterminate colitis (IC), other non-infectious gastroenteritis, enteritis, enteritis and colitis (such as non-microscopic colitis including collagenous colitis and lymphocytic colitis, radiation-induced, toxin-induced, allergy-induced, diet-induced, ischemic, eosinophilic gastroenteritis, enteritis, enteritis or colitis, segmental colitis associated with diverticula, diversion colitis and Behcet's colitis), as well as pouchitis.

[0131] Preferably, the inflammatory bowel disease is selected from the group consisting of Crohn's disease and ulcerative colitis.

[0132] The composition of the present invention can be used in combination with an anti-inflammatory diet or a low-carbohydrate diet.In particular, such an anti-inflammatory diet may include: 1) a pro-inflammatory diet, in particular, avoiding refined carbohydrates, fried foods, soft drinks and other sweetened beverages, red meat and processed meat;2) an anti-inflammatory diet, in particular, preferring the intake of olive oil, green leafy vegetables such as spinach or kale, nuts such as almonds and walnuts, oily fish such as salmon, mackerel, tuna and sardines, and fruits such as strawberries, blueberries, cherries, oranges, apples and tomatoes.

[0133] The subject to be treated with the composition of the present invention is an animal, preferably a mammal. In one embodiment, the subject is a domestic or farm animal, such as a dog, cat, cow, sheep, horse, or rodent. In a preferred embodiment, the subject is a human, including adults, children, newborns, and prenatal humans. As used herein, the terms "subject", "individual" and "patient" are interchangeable.

[0134] The dosage of the active compound as defined above, i.e. kynurenine aminotransferase, the live recombinant bacteria genetically modified to express and secrete said kynurenine aminotransferase, and / or xanthurenic acid or its derivatives, or any pharma- ceutically acceptable salts or solvates thereof, can be appropriately adjusted according to criteria such as age, symptoms, weight, and intended use, such that a therapeutically effective amount is obtained. The term "therapeutically effective amount" as used herein refers to the amount required to obtain a beneficial effect on the disease being treated, i.e. to prevent, eliminate, or reduce at least one adverse effect of the disease. The therapeutically effective amount is preferably defined as the amount required to obtain an effect on any symptom of the disease, such as intestinal inflammation or diarrhea, fever, or pain.

[0135] In some embodiments, the composition contains 10 3 ~10 11 The amount of live recombinant bacterial cells as defined above taken per day may be 1×10 6 ~1×10 11 CFU / body, preferably 0.1×10 9 ~10×10 9 CFU / body, more preferably 0.3×10 9 ~5×10 9 The content of live recombinant bacterial cells as defined above contained in the composition of the invention to be orally ingested may be, for example, 1% to 100% (w / w, i.e., bacterial dry mass / total dry mass of the composition), preferably 1% to 75% (w / w), and more preferably 5% to 50% (w / w).

[0136] In some other embodiments, the composition may contain 0.001 mg to 1 mg of KAT enzyme as defined above per mg of composition. In particular, the amount of KAT enzyme as defined above taken per day may be 0.001 mg / body to 100 mg / body. The content of KAT enzyme as defined above contained in the composition of the present invention to be orally taken may be, for example, 0.1% to 100% (w / w, i.e., KAT enzyme mass / total dry mass of the composition), preferably 0.1% to 75% (w / w).

[0137] In some other embodiments, the composition may contain 0.001 mg to 1 mg of xanthurenic acid or its derivative as defined above per mg of composition. In particular, the amount of xanthurenic acid or its derivative as defined above taken per day may be 0.001 mg / body to 100 mg / body. The content of xanthurenic acid or its derivative as defined above contained in the composition of the present invention to be orally taken may be, for example, 0.1% to 100% (w / w, i.e., xanthurenic acid or derivative mass / total dry mass of the composition), preferably 0.1% to 75% (w / w), more preferably 0.5% to 50% (w / w).

[0138] The compositions of the present invention can be administered as a single dose or in multiple doses. In particular, depending on the age or physiological condition of the subject, the daily dose may be divided to facilitate administration, for example, one dose in the morning and another in the evening.

[0139] In some embodiments, the compositions can be administered periodically, preferably between daily and monthly, more preferably between daily and every two weeks, more preferably between daily and weekly, hi some particular embodiments, the compositions can be administered daily.

[0140] The duration of treatment with the compositions of the present invention may be comprised between one day and several years, preferably between one day and one year, more preferably between one day and six months.

[0141] All references cited herein are incorporated by reference into this application. Other features and advantages of the present invention will become apparent from the following examples, which are given for purposes of illustration and are not intended to be limiting. EXAMPLES

[0142] Example 1 Materials and Methods mouse Male and female C57BL / 6JRj mice were purchased from Janvier (France). - / - Mice were obtained from the Jackson laboratory (JAX stock #002831) (Fernandez-Salguero et al. Science. 1995, 268, 722-726) and housed at the Saint-Antoine Research Center. - / - Mice (Kreymborg et al., J. Immunol. 2007, 179, 8098-8104) were obtained and bred at the Transgenose Institute (TAMM~CNRS, Orleans, France). All mice were bred in an IERP facility (INRA, Jouy-en-Josas, France) certified by the French "Direction Départementale de la Protection des Populations (DDPP78)". All experiments were performed in accordance with the Comite d'Ethique en Experimentation Animale (COMETHEA C2EA - 45, Jouy en Josas, France).

[0143] DSS Model Seven-week-old C57BL / 6JRj mice from Janvier lab were housed in our specific pathogen-free animal facility at IERP (INRA, Jouy en Josas, France). For all experiments, 5-10 female mice per group were used and kept in a temperature-controlled (23°C) facility with a strict 12-h light / dark cycle and food and water available ad libitum. After 1 week of acclimation, we changed the water to DSS 2% (MP Biomedical) for 7 days (day 0 to day 7) and a recovery period was performed until day 12 (5 days). Weight loss and DAI (Disease Activity Index) were performed daily. After 12 days, samples were taken.

[0144] [Table 6]

[0145] colon histology Distal colonic segments (cut into 3 parts) were harvested on day 12 after the DSS model, directly placed in PFA (Rothi®-Histofix 4%) for 48 hours, transferred to ethanol 70% until standard prefixation automat and paraffin embedded. HES staining was performed on 5 μm sections. Scoring was performed on the worst section and scored as previously described (Sokol et al., Gastroenterology. 2013 Sep;145(3):591-601, e3.).

[0146] statistical analysis Data were analyzed using Prism version 7 (Graphpad Software, San Diego, USA). Nonparametric Mann-Whitney test or parametric one-way ANOVA test with multiple Bonferroni comparison test was performed. Values ​​are expressed as mean ± SEM. Statistical significance is expressed as p value. **** <0.0001, *** <0.001, ** <0.01, * Defined as <0.05.

[0147] result During a model of intestinal inflammation induced by DSS (dextran sulfate sodium) in mice, the kynurenine pathway was monitored as previously described (Lefevre et al., Talanta 195 (2019) pp. 593-598). The metabolites that compose this pathway are tryptophan, kynurenine (KYNU), kynurenic acid (KYNA), 3-hydroxykynurenine (3HK), xanthurenic acid (XANA), 3-hydroxyanthranilic acid (3-HAA), picolinic acid and quinolinic acid. It was observed that the kinetics of these metabolites differed from each other. In detail, the kinetics of kynurenine and quinolinic acid correlated with inflammation, whereas that of xanthurenic acid or kynurenic acid had the opposite kinetics. This phenomenon is particularly evident at the peak of inflammation at D9 (Figure 1A-B).

[0148] This phenomenon was then investigated in the human context. For this purpose, fecal and serum samples from patients participating in a clinical trial evaluating fecal microbiota transplantation in Crohn's disease (NCT02097797) were analyzed. Metabolomic analysis targeting tryptophan metabolites was performed on these samples, and correlations were made with various clinical, endoscopic and biological markers of disease activity. Negative correlations were observed between several markers of disease activity and KYNA and XANA (as well as with the ratios between KYNA, XANA and their precursors, kynurenine and 3-hydroxykynurenine, respectively). The opposite was observed for kynurenine and quinolinic acid (data not shown). These results therefore confirmed the human relevance of the data identified in mice.

[0149] Based on these results, it was hypothesized that XANA and KYNA might have anti-inflammatory effects. To further investigate the effects of these metabolites, XANA and KYNA were administered to mice undergoing DSS-induced colitis. 8 mg KYNA and 6 mg XANA were delivered orally to each mouse daily. The doses are consistent with the literature for KYNA (R. Gill and GN Woodruff, 1990, European Journal of Pharmacology). Daily measurements of weight loss and colitis activity index showed that these two metabolites have anti-inflammatory effects (Figure 2A-B). At the end of the model, day 12, the colon length in these mice was longer and the histological score was lower (Figure 2C-E), confirming the protective effect of KYNA and XANA. Colonic expression of many pro-inflammatory cytokines, such as IL-1 or IL-17 (measured by nanostring® technology), was also reduced in mice treated with XANA or KYNA (data not shown). In addition, perivascular injection of XANA and KYNA also induced protection similar to that observed when these metabolites were given orally, suggesting a systemic effect (Figures 3A-E).

[0150] Example 2 Materials and Methods Cloning of mouse alpha-aminoadipate aminotransferase (AADAT) in Escherichia coli Codon usage of the gene synthesized by GeneArt (pMA:muAADAT plasmid) encoding mouse AADAT (muAADAT, SEQ ID NO: 13). The DNA fragment encoding muAADAT was then recovered after digestion with NheI and XhoI restriction enzymes and cloned into pStaby 1 vector (DelphiGenetics) previously digested with the same enzymes. The use of pStaby 1 plasmid (Figure 4A) allows the introduction of a C-terminal 6-histidine tag (His tag) that allows the subsequent purification of muAADAT under the control of the phage T7 RNA polymerase promoter (T7 polymerase) using affinity chromatography. The final vector pStaby:muAADAT (Figure 4B) was transferred into T7 Express Competent E. coli (NEB) and transformants were grown overnight (ON) at 37°C in 10 mL of Luria-Bertani medium containing ampicillin (Amp, 100 μg / mlL) with shaking at 180 rpm. Plasmid DNA was extracted from positive clones and sequenced to confirm their identity.

[0151] Expression and purification of recombinant mouse AADAT protein in Escherichia coli E. coli strains expressing muAADAT were grown at 37°C in 100 mL LB supplemented with 100 μg / ml Amp ON with shaking at 180 rpm, then in 10 L LB with 100 μg / ml Amp ON at 37°C. Once an optical density (OD600nm) of 0.8-1.0 was reached, gene expression was induced by adding 0.25 mM IPTG, and the cultures were incubated at 16°C ON with shaking at 180 rpm (Figure 4C). Bacteria were harvested by centrifugation, cell pellets were washed with PBS, and resuspended in 100 ml Binding Buffer (PBS buffer supplemented with 0.1% 10X Triton and 1X protease inhibitors, pH 7.4-300 mM NaCl, Rock). Cells were then sonicated in ice for 20 min at 40% amplitude for 5 s, followed by 3 s stop. The lysate was then centrifuged at 15,000 g for 30 min at 4° C. to separate the soluble fraction from the cell pellet. The soluble fraction containing AADAT was purified by affinity chromatography. 100 mL of the supernatant was incubated with 4 mL of Ni-NTA agarose resin (ref. R901-15 from Invitrogen) for 1 h at 4° C. and then loaded onto a BioRad column. The AADAT protein immobilized on the resin was washed with 100 mL of PBS buffer pH 7.4-500 mM NaCl, then with 25 mL of PBS buffer pH 7.4-300 mM NaCl-20 mM imidazole and 10 mL of buffer.PBS buffer pH 7.4-300 mM NaCl-40 mM imidazole. The AADAT protein was eluted with 8 ml of PBS buffer pH 7.4-300 mM NaCl-300 mM imidazole (FIG. 4D). Fractions 2-6 were pooled and dialyzed against 1 L PBS, 50% glycerol-300 mM NaCl Specta / Port 6. Protein was stored at -20°C. Precast BioRad Mini Protean TGX stain-free, 4-20% gels were run to control the different steps of purification.

[0152] Validation of AADAT activity test The activity test is based on the disappearance of the AADAT substrates kynurenine and 3-hydroxykynurenine. Reaction mixtures (final volume 50 μL) containing 10 mM L-kynurenine or 3-hydroxykynurenine, 2 mM α-oxoglutarate, 40 μM PLP (pyridoxal 5'-phosphate) and 0 or 1 μL of purified protein sample prepared in buffer 100 mM potassium phosphate (pH 7.4). The mixtures were then incubated for 15 min at 37 °C and the reaction was stopped by the addition of an equal volume of 30% acetic acid. The supernatant of the reaction mixture obtained by centrifugation at 3000 g for 10 min at 4 °C was mixed in equal volume with Ehrlich's solution and incubated for 15 min at room temperature to obtain a colorimetric reaction. In parallel, a standard range of kynurenine or 3-hydroxykynurenine from 0 μM to 1000 μM was made under the same conditions. The amount of kynurenine or 3-hydroxykynurenine present in the samples was measured by spectrophotometer at OD of 492 nm and calculated using the standard range (Figure 4E). Validation of the production of KYNA and XANA in vitro in the presence of KYNU (1000 μM) during 15 min by the action of our enzyme was performed (Figure 4F). The dose effect can be observed from the conversion of KYNU to KYNA and XANA.

[0153] result Once all checks were made, mice were then administered purified AADAT protein perivascularly during a colitis model induced by DSS. Taking into account our enzymatic degradation of KYNU and 3HK (Figure 4E) and the production of KYNA and XANA in the supernatant (Figure 4F), three doses were evaluated at 1 μL (10, 1 and 0.1 μL per day and per mouse). The results obtained show protection, with a dose effect, both in terms of weight loss and clinical score, but also in terms of colon length or histological score at day 12 (Figures 5A-E). A protective effect is also seen at the two lower doses.

[0154] Taken together, these results indicate a strong therapeutic potential via administration of XANA and / or via polarization of tryptophan metabolism towards protective metabolites of the kynurenine pathway by use of the recombinant enzyme AADAT.

Claims

1. 1. A composition for use in the treatment of inflammatory bowel disease, comprising: Kynurenine aminotransferase (KAT), and / or - a live recombinant bacterium that has been genetically modified to express and secrete said kynurenine aminotransferase, and / or - a product of said kynurenine aminotransferase which is xanthurenic acid, a derivative thereof, or any pharmaceutically acceptable salt or solvate thereof. A composition comprising:

2. 2. The composition of claim 1, wherein the inflammatory bowel disease is selected from the group consisting of Crohn's disease, ulcerative colitis, indeterminate colitis (IC), other non-infectious gastroenteritis, enteritis, enterocolitis and colitis, and pouchitis.

3. 2. The composition of claim 1, wherein the inflammatory bowel disease is selected from the group consisting of Crohn's disease and ulcerative colitis.

4. 2. The composition of claim 1, wherein the inflammatory bowel disease is selected from the group consisting of enteritis, enterocolitis, pouchitis, and non-infectious gastroenteritis other than Crohn's disease, ulcerative colitis, and indeterminate colitis.

5. 2. The composition of claim 1, wherein the inflammatory bowel disease is selected from the group consisting of enteritis, enterocolitis, and pouchitis.

6. 2. The composition of claim 1, wherein the kynurenine aminotransferase is selected from the group consisting of human kynurenine / alpha-aminoadipate aminotransferase (KAT II), human kynurenine-oxoglutarate transaminase 1 (KAT I), human kynurenine-oxoglutarate transaminase 3 (KAT III), human mitochondrial aspartate aminotransferase (KAT IV), orthologs thereof, and variants thereof, wherein the variants have at least 80% sequence identity to human KAT I, human KAT II, ​​human KAT III, human KAT IV, or any orthologs thereof, and exhibit kynurenine aminotransferase activity.

7. 2. The composition of claim 1, wherein the kynurenine aminotransferase is selected from the group consisting of human KAT II, ​​human KAT III, human KAT IV, orthologs thereof, and variants thereof, wherein the variants have at least 80% sequence identity to human KAT II, ​​human KAT III, human KAT IV, or any orthologs thereof, and exhibit kynurenine aminotransferase activity.

8. 2. The composition of claim 1, wherein the kynurenine aminotransferase is selected from the group consisting of human KAT II, ​​its orthologs, and variants thereof, wherein the variants have at least 80% sequence identity to human KAT II or to any ortholog thereof and exhibit kynurenine aminotransferase activity.

9. 2. The composition of claim 1, wherein the kynurenine aminotransferase is selected from the group consisting of KAT proteins of SEQ ID NOs: 1 to 32, and variants thereof having at least 80% sequence identity to any of SEQ ID NOs: 1 to 32 and exhibiting kynurenine aminotransferase activity.

10. 2. The composition of claim 1, wherein the kynurenine aminotransferase is selected from the group consisting of KAT proteins of SEQ ID NOs: 10 to 16, and variants thereof having at least 80% sequence identity to any of SEQ ID NOs: 10 to 16 and exhibiting kynurenine aminotransferase activity.

11. 11. The composition of claim 1, comprising the kynurenine aminotransferase.

12. 11. The composition of any one of claims 1 to 10, comprising a recombinant bacterium that has been genetically modified to express and secrete the kynurenine aminotransferase.

13. 13. The composition of claim 12, wherein the recombinant bacterium is selected from the group consisting of bacteria belonging to the genera Allobaculum, Adrenocluzia, Anaerostipes, Bifidobacterium, Propionibacterium, Bacteroides, Eubacterium, Enterococcus, Ruminococcus and Faecalis bacterium, Escherichia coli, and lactic acid bacteria such as bacteria belonging to the genera Lactobacillus, Lactococcus and Streptococcus.

14. xanthurenic acid, its derivatives or any pharmaceutically acceptable salts or solvates thereof, wherein the xanthurenic acid derivatives are represented by the formula (I): 【Chemical 1】 [In the formula, R 1 , R 2 and R 3 represents a hydrogen atom, a hydroxyl group, a halogen atom, -CO-R 8 group or -CO 2 R 8 Group(R 8 is H or C 1～10 alkyl group), -NR 9 R 9' (R 9 and R 9' are independently a hydrogen atom or C 1～10 alkyl group), a nitro group, a cyano group, a C optionally substituted with a halogen atom 1～10 Alkyl, C 2～10 Alkenyl or C 2～10 C optionally substituted by an alkynyl group and a halogen atom 1～10 independently selected from the group consisting of alkyloxy; R 4 and R 6 is a hydrogen atom, and C 1～10 independently selected from the group consisting of alkyl groups; R 5 represents a hydroxyl group, a hydrogen atom, -NR 7 R 7' (R 7 and R 7' are independently a hydrogen atom or C 1～10 alkyl group), C 1～10 Alkyl groups, and C 1～10 alkoxy groups] or a tautomeric form thereof.

15. 15. The composition of claim 14, wherein the xanthurenic acid derivative is selected from the group consisting of oxo-xanthurenic acid (OXA) and di-oxo-xanthurenic acid (DOXA).

16. 11. The composition of any one of claims 1 to 10, comprising xanthurenic acid or any pharmaceutically acceptable salt or solvate thereof.

17. 11. The composition of any one of claims 1 to 10, further comprising or used in combination with nicotinamide adenine dinucleotide or a precursor thereof.

18. 11. Use of a composition as defined in any one of claims 1 to 10 for the manufacture of a medicament for the treatment of inflammatory bowel disease.

Images