Use of O antigen in the treatment of bacterial infections

Abstract

The present invention relates to the use of O antigen in the treatment of bacterial infections. In one aspect of the present invention, the use of O antigen in the manufacture of a therapeutic agent for bacterial infections is provided, wherein the administered agent mobilizes migratory promonocytes (TpMos) from the bone marrow to the peripheral blood of the subject. In another aspect, an O antigen for use in the treatment of bacterial infections is provided, which mobilizes TpMos from the bone marrow to the peripheral blood of the subject. In yet another aspect, a method is provided for mobilizing proliferating migratory promonocytes (TpMos) from the bone marrow to the peripheral blood of the subject, the method comprising administering a therapeutically effective amount of O antigen to the subject.

Description

[Technical Field]

[0001] This invention generally relates to the treatment of bacterial infections, and more particularly to the use of O antigen for the treatment of bacterial infections. [Background technology]

[0002] Sepsis is one of the leading causes of death in the intensive care unit. Significant research efforts have been dedicated to elucidating the pathogenesis of sepsis and developing intervention strategies such as antibiotic therapy and intravenous fluid resuscitation. However, the complex and rapid progression of sepsis limits the success of current treatments and biomarkers for predicting outcomes.

[0003] Despite advances in supportive care for sepsis, the mortality rate from sepsis remains high. Because sepsis often occurs in conjunction with bacterial infections, antibiotic treatment is commonly used to prevent adverse outcomes. However, broad-spectrum antibiotic therapy is becoming less effective against bacteria and is increasingly proving to have detrimental effects on patients due to antibiotic resistance, which is emerging as a global threat to public health systems worldwide. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Therefore, there is a need for new intervention strategies for the treatment of bacterial infections and sepsis that overcome the shortcomings of the prior art. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, in conjunction with the accompanying drawings and the background of this disclosure. [Means for solving the problem]

[0005] In one embodiment, the present invention provides the use of O antigen in the manufacture of a pharmaceutical product for treating a bacterial infection, wherein the administered pharmaceutical product mobilizes pre-transition monocytes (TpMos) from the bone marrow of the target to the peripheral blood.

[0006] In one embodiment, the bacterial infection is bacterial sepsis.

[0007] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0008] In one embodiment, the O antigen comprises the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0009] In one embodiment, the O antigen is an O antigen derived from Escherichia coli serotype O18 or O111.

[0010] In one embodiment, Escherichia coli serotype O18 is the Escherichia coli UTI89 strain.

[0011] In one embodiment, the agent is used as adjuvant therapy.

[0012] In another aspect, there is provided a pharmaceutical composition comprising (a) a therapeutically effective amount of an O antigen comprising the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc; and (b) one or more pharmaceutically acceptable carriers and / or diluents.

[0013] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0014] In one embodiment, the O antigen is an O antigen derived from Escherichia coli serotype O18 or O111.

[0015] In one embodiment, Escherichia coli serotype O18 is the Escherichia coli UTI89 strain.

[0016] In another aspect, there is provided an O antigen for use in the treatment of a bacterial infection, wherein the O antigen mobilizes TpMos from the bone marrow to the peripheral blood of a subject.

[0017] In one embodiment, the bacterial infection is bacterial sepsis.

[0018] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0019] In one embodiment, the O antigen includes the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0020] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0021] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0022] In one embodiment, the O antigen is used as an adjunctive therapy.

[0023] In one embodiment, a method is provided for treating a bacterial infection, comprising administering a therapeutically effective amount of a composition containing the O antigen to a subject, wherein the administration of the O antigen mobilizes migratory promonocytes (TpMos) from the bone marrow to the peripheral blood of the subject.

[0024] In one embodiment, the bacterial infection is bacterial sepsis.

[0025] In one embodiment, the O antigen is an antigen derived from Escherichia coli.

[0026] In one embodiment, the O antigen includes the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0027] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0028] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0029] In one embodiment, the amount of O antigen present in the composition is 40 ng to 400 ng.

[0030] In one embodiment, the O antigen is used as an adjunctive therapy.

[0031] One embodiment provides a method for recruiting translocation promonocytes (TpMos) from the bone marrow of a subject into the peripheral blood, the method comprising administering a therapeutically effective dose of O antigen to the subject.

[0032] In one embodiment, the therapeutically effective dose of O antigen is 40 ng to 400 ng.

[0033] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0034] In one embodiment, the O antigen includes the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0035] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0036] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0037] In another embodiment, a method is provided for determining the prognosis of a subject having sepsis caused by a Gram-negative bacterial infection, the method comprising detecting the presence of migratory promonocytes (TpMos) in a blood sample taken from the subject, the presence of TpMos in the blood sample indicating a favorable clinical outcome.

[0038] Advantageously, the inventors of this invention have demonstrated that the O antigen mobilizes TpMos from the bone marrow to the peripheral blood of the target, and that this has a therapeutic effect against sepsis.

[0039] The present invention will be better understood by referring to the following detailed description in conjunction with the examples (not limited to) and the accompanying drawings. [Brief explanation of the drawing]

[0040] [Figure 1A]Figure 1 shows the appearance of Ly6Chi proliferative monocytes, identified as transitional promonocytes (TpMos) recruited from the bone marrow (BM) to the peripheral blood during bacterial infection and sepsis. (AB) Representative fluorescence-activated cell sorting (FACS) plots (A) and the number of proliferative Ly6Chi monocytes in the blood (B) of PBS control mice and E. coli-infected mice incorporating BrdU. Results are expressed as mean values ​​(n=4) and represent one representative value out of three experiments. ***P<0.001 (Student's t-test). [Figure 1B] (AB) Representative fluorescence-activated cell sorting (FACS) plots (A) and the number of proliferative Ly6Chi monocytes in the blood of PBS control mice and E. coli-infected mice with BrdU incorporated into their bodies. (B). Results are expressed as mean values ​​(n=4) and represent one representative value out of three experiments. ***P<0.001 (Student's t-test). [Figure 1C] (C) Mice were exposed to CLP-induced sepsis, and proliferative Ly6Chi monocytes in the blood were quantified based on BrdU uptake at the indicated time points. Results are expressed as mean values ​​(n=5) and represent one representative value out of three experiments. **P<0.01,****P<0.0001 (one-way ANOVA). [Figure 1D] (D) Homogeneous manifold approximation and projection (UMAP) analysis of monocyte subsets from uninfected bone marrow cells (left), uninfected blood cells (center), and E. coli-infected blood cells (right). Parameters used for UMAP projection included Ly6C, CXCR4, CD49f, CD115, cKit, CD43, CX3CR1, and CD48. Monocyte subsets containing proliferative (Fucci+) Ly6Chi monocytes were manually gated and superimposed onto the UMAP space. [Figure 1E] (E) Number of BMTpMos (left) and blood Ly6Chi proliferative monocytes (right) at the indicated time point. Results are expressed as mean values ​​(n=4) and represent one representative value from the two experiments. *P<0.05, ***P<0.001, ****P<0.0001 (one-way ANOVA). [Figure 1F](F)GFP-tagged TpMos and tdTomato-tagged MatMos (mature monocytes) were resuspended in a 1:1 ratio and transplanted into recipient mice via the intrafemoral pathway (IBM). Subsequently, recipient mice were intraperitoneally injected with PBS or E. coli, and cells were collected for analysis 9 hours post-infection (left). A representative FACS plot of the transplanted cells shows the in vivo uptake of BrdU (center). The percentage of BrdU-positive cells among the transplanted cells is shown (right). Results are shown as mean values ​​(n=4-5), representing one out of three experiments. ***P<0.001 (one-way ANOVA). [Figure 2A] Figure 2 shows that TpMos conferred a protective response and improved the survival rate of septic mice. (A) LPS-stimulated control BM TpMos and MatMos were analyzed for apoptotic cells using FLICA polycaspase 3 hours later. Results are expressed as mean values ​​(n=4-6) and represent one representative value out of three experiments. ***P<0.001 (Student's t-test). [Figure 2B] (B) TpMos and MatMos cells were selected from CD45.1 mice and transplanted into CLP-induced CD45.2 recipient mice via the intraperitoneal (ip) pathway. Transplanted cells were analyzed for IL-6, IL-1β, TNF-α, and iNOS expression on days 1, 3, and 5 post-transplantation. Results are expressed as mean values ​​(n=4-6) and represent one of the three experiments. ns: no significant difference, *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001 (Student's t-test). [Figure 2C] (C)TpMos or MatMos mice were selected and adopted into recipient mice immediately after CLP treatment. The survival rates of these mice were evaluated using Kaplan-Meier survival curves. The results are representative of one of three experiments (n=10). *P<0.05 (Mantel-Cox method). [Figure 3]Figure 3 shows that TpMo recruitment is specific to bacterial-induced inflammatory conditions. Representative FACS plots showing TpMos (CD62LhiCXCR4hi) in CLP-induced sepsis models (A), malaria (B), influenza (C), dengue fever (DENV) and Zika fever (ZIKV) models (D), a high-fat diet model (E), and a pregnancy model (F). [Figure 4A] Figure 4 shows that TpMo recruitment is induced by specific Gram-negative bacterial O antigen glycan structures. (A) Number of circulating TpMos in mice infected with Gram-negative bacteria (Escherichia coli, A. baumannii, P. aeruginosa) and Gram-positive bacteria (S. aureus, E. faecalis, and E. faecium). Results are expressed as mean values ​​(n=4-5 per group). ****P<0.0001 (one-way ANOVA). [Figure 4B] (B) Number of circulating TpMos in mice infected with different E. coli strains (MG1655, L5, L9, UTI89) with different O antigen structures and densities. Results are expressed as mean values ​​(n=4-7 per group) and represent one representative value out of two experiments. ****P<0.0001 (one-way ANOVA). [Figure 4C] (C) Number of circulating TpMos in mice administered LPS of different O antigens (O55, O111). Results are expressed as mean values ​​(n=4 per group) and represent one of the two experiments. ****P<0.0001 (one-way ANOVA). [Figure 4D] (D) Glycan structures common to the O18 and O111 antigens that were able to induce TpMo mobilization are highlighted. O18A is a subtype of the O18 serotype. [Figure 5] Figure 5 shows a simplified diagram of monocyte development in the bone marrow (BM). Monocytes differentiate from common monocyte progenitor cells (cMoPs) through transitional progenitor cells to mature Ly6Chi monocytes (MatMos). These transitional progenitor cells were previously called transitional promonocytes (TpMos). TpMos are functionally immature, actively proliferate in the bone marrow, do not respond to recruitment signals, and were thought to be a storage depot for MatMos. [Figure 6]Figure 6 illustrates the importance of infiltrating monocytes during bacterial infection. During inflammation, monocytes are rapidly recruited to the site of inflammation, differentiate into monocyte-derived macrophages to replenish the niche, and provide effector functions such as phagocytosis and production of pro-inflammatory cytokines to reduce the bacterial load. [Figure 7] Figure 7 shows that bacterial phagocytosis leads to monocyte depletion and cell death. Monocytes have low mitochondrial and ATP levels. Therefore, bacterial ingestion often leads to monocyte depletion and subsequent cell death, limiting their ability to differentiate into macrophages. [Figure 8] Figure 8 shows important findings regarding TpMos. In bacterial infections and sepsis, TpMos efficiently migrated to the peritoneum and maintained proliferative capacity, similar to MatMos. TpMos showed an enhanced response to CSF-1 and generated more macrophages compared to MatMos. TpMo and TpMo-derived macrophages had higher viability and lower inflammatory activity compared to MatMo and MatMo-derived macrophages. Furthermore, TpMos did not contribute to cytokine storms. [Figure 9] Figure 9 shows that TpMos may influence the outcome of sepsis. To determine whether TpMos is protective or harmful in sepsis, TpMos and MatMos were selected and adopted into sepsis mice, and their survival rates were compared. In one aspect of the present invention, adoptive transplantation of TpMos improved sepsis survival outcomes in the subjects, suggesting that TpMos recruitment protects the bacterial immune response. [Figure 10] Figure 10 shows the components of lipopolysaccharide (LPS). LPS constitutes the main component of the cell wall of Gram-negative bacteria. It is composed of lipid A, core oligosaccharides, and O-type polysaccharide (O-antigen). Various forms of LPS play important roles in bacterial toxicity, permeability, and cell adhesion. Of the components that form the LPS structure, the O-antigen is thought to be involved in bacterial toxicity. [Figure 11]Figure 11 shows that the presence of the O antigen and serotype influences bacterial pathogenicity. Since the O antigen is thought to be involved in bacterial toxicity, we investigated whether the O antigen plays a role in TpMo recruitment using E. coli strains with different O antigen structures and pathogenicity. As described in this invention, data were acquired and studied to determine the effect of using the O antigen to recruit TpMos. [Figure 12] Figure 12 shows that bacterial toxicity plays a role in inducing TpMo release. In contrast to MatMos, which did not show a trend in numbers associated with different strains at various doses, TpMos was shown to be released into the circulatory system when mice were infected with UTI89 carrying the O18 antigen. [Figure 13] Figure 13 shows that TpMos are transitional progenitor cells of mature Ly6Chi monocytes (MatMos). In a steady state, they are functionally immature, actively proliferate in the bone marrow, and function as a storage depot for MatMos in the bone marrow. [Figure 14] Figure 14 shows the behavior and function of TpMos during severe inflammation. In bacterial infections and sepsis, TpMos can enter the circulatory system from the bone marrow and invade the site of inflammation. TpMos exerts a protective effect against sepsis by actively replenishing the macrophage pool and balancing the pro-inflammatory cytokines produced by MatMos. [Figure 15] Figure 15 shows the sepsis intervention strategy. [Figure 16] Figure 16 shows a typical research and development plan based on one embodiment of the present invention. [Figure 17] Figure 17 shows the presence of TpMos in sepsis patients. This is a representative FACS plot showing the presence of TpMos (CXCR4 positive, Ki67 positive) in the circulating blood of sepsis patients discharged from the ICU. [Modes for carrying out the invention]

[0041] In one embodiment, the present invention provides the use of O antigen in the manufacture of a pharmaceutical for treating a bacterial infection, wherein the administered drug mobilizes migratory promonocytes (TpMos) from the bone marrow to the peripheral blood of the target.

[0042] The term "O antigen," also known as "O-specific polysaccharide" or "O side chain," refers to the main component of surface lipopolysaccharides (LPS) of Gram-negative bacteria, which are structurally highly diverse. As used herein, "O antigen" may include references to the O antigen itself, the O antigen as part of a complete lipopolysaccharide (LPS), or the O antigen as part of a complete LPS on a bacterial cell.

[0043] In this specification, the terms “to treat” or “to treat” in the context of treating diseases such as sepsis mean to improve the clinical outcome of patients with the disease. This includes improving the survival rate of patients with the disease.

[0044] In this specification, migratory promonocytes (TpMo) are cells having the following surface marker: Ly6C hi CXCR4 hi , CCR2 lo CD62L hi CD11b lo , and CD31 hi Transitional promonocytes (TpMos) are normally actively proliferating. In relation to cells, the term "proliferation" refers to cells in the S / G2 / M phase of the cell cycle. The terms "transitional promonocyte" and "proliferating transitional promonocyte" are used interchangeably. TpMos are in an active proliferative stage, which is indicated by the expression of BrdU by the BrdU assay or by the expression of the Fucci signal in Fucci-474 transgenic mice, where the Fucci signal is a fluorescent protein that emits green light and labels cells in the S / G2 / M phase of the cell cycle.

[0045] The term "bacterial infection" includes conditions in which the subject is infected with bacteria. As used herein, the term "bacterial infection" is also used to describe disease conditions characterized by the presence of bacteria, such as sepsis. As used in this book, the term "sepsis" refers to a life-threatening organ dysfunction caused by an imbalance in the host's response to infection. Sepsis is most commonly caused by bacterial infection, but can also be caused by viral or fungal infections. As used herein, the term "bacterial sepsis" refers to sepsis caused by bacteria.

[0046] The term “sepsis” is also used to refer to a harmful systemic inflammatory response to infection, and is formally defined as the presence (possible or demonstrated) of an infection and the manifestation of systemic symptoms of the infection. In this specification, the term “sepsis” also includes complications of sepsis, such as “severe sepsis” and “septic shock.”

[0047] The term "peripheral" includes infection sites in peripheral blood and tissue. Peripheral blood refers to blood that circulates in the body's vascular system and is not concentrated in any particular organ. The terms "mobilize to the periphery" and "mobilize into circulation" are used interchangeably.

[0048] In one embodiment, the bacterial infection is bacterial sepsis.

[0049] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0050] In one embodiment, the O antigen includes the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0051] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0052] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0053] In one embodiment, the drug is used as an adjunct treatment.

[0054] As used herein, the term “adjunctive therapy” refers to treatments used in conjunction with primary therapy to assist or enhance primary therapy. Adjunctive therapy may enhance the effectiveness of primary therapy in treating a disease. The terms “adjunctive therapy,” “adjunctive treatment,” “adjunctive therapy,” and “adjunctive treatment” are used interchangeably. The term “treatment” may refer to preventive and / or therapeutic measures.

[0055] In another embodiment, a pharmaceutical composition is provided comprising (a) a therapeutically effective amount of an O antigen containing the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc; and (b) one or more pharmaceutically acceptable carriers and / or diluents.

[0056] As used herein, the term “pharmaceutical composition” includes any pharmaceutical preparation or formulation suitable for administration to a target requiring it. This composition may be suitable for parenteral administration to a patient, either in its own form or in combination with a delivery agent. The carrier is selected from the group consisting of nanoparticles such as polymer nanoparticles, liposomes such as pH-sensitive liposomes and antibody-conjugated liposomes, viral vectors, cationic lipids, polymers, and cell-penetrating peptides. It is understood that the pharmaceutical compositions provided in accordance with this disclosure may be administered by any means known in the art. Pharmaceutical compositions may be administered orally, rectally, transmucosally, intraintestinally, intramuscularly, subcutaneously, intramedullarily, intraspinally, directly into the ventricle, intravenously, intravitreously, intraperitoneally, intranasally, or intraocularly.

[0057] A pharmaceutically acceptable carrier is generally a substance suitable for administration to a subject that is not biologically harmful or causes undesirable effects. Such carriers are typically inactive components of pharmaceuticals. Typically, the carrier is administered to the subject together with the active ingredient without causing undesirable biological effects or interacting in a harmful manner with any other components of the pharmaceutical composition containing the carrier. Suitable pharmaceutical carriers are described in Martin, Remington's Pharmaceutical Sciences, 18th Ed., Mack Publishing Co., Easton, Pa., (1990), which is incorporated herein by reference.

[0058] Pharmaceutical compositions may include pharmaceutically acceptable salts, which may refer to relatively non-toxic inorganic and organic acid addition salts of the compounds described herein. These salts may be prepared in situ during the final isolation and purification of the compounds, or by separately reacting the purified compounds in the form of free bases with suitable organic or inorganic acids and then isolating the salts thus formed. Typical salts include hydrobromide, hydrochloride, sulfate, bisulfate, nitrate, acetate, oxalate, valerate, oleate, palmitate, stearate, laurate, borate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, naphthylmesylate, glucoheptonate, lactibsonate, and laurylsulfonate. These may include cations based on alkali metals and alkaline earth metals such as sodium, lithium, potassium, calcium, and magnesium, as well as non-toxic ammonium, quaternary ammonium, and amine cations, including but not limited to ammonium, tetramethylammonium, tetraethylammonium, methylamine, dimethylamine, trimethylamine, triethylamine, and ethylamine (e.g., Berge SM, et al, “Pharmaceutical Salts,” J.Pharm.Sci., 1977;66:1-19, the contents of which are incorporated herein by reference).

[0059] The pharmaceutical formulations of this disclosure can be conveniently provided in unit dose form and can be prepared according to prior art well known in the pharmaceutical industry. Such art includes the step of combining an active ingredient with a pharmaceutical carrier or excipient. Generally, formulations are prepared by uniformly mixing the active ingredient with a liquid carrier or a finely divided solid carrier, or both, and then shaping the product as needed.

[0060] Combination therapy with additional therapeutic agents may also be considered in this disclosure. As used throughout this specification, the terms “combination” or “combination therapy” encompass the administration of the therapeutic agents referred to, in the same or different pharmaceutical formulations, simultaneously or at different times, to a subject suffering from a disease, disorder, or condition. When the therapeutic agents are administered at different times, they must be administered close enough to produce an enhancement or synergistic effect. In such cases, it is typically assumed that both therapeutic agents are administered within approximately 12 to 24 hours of each other, more preferably within approximately 6 to 12 hours of each other. However, in some situations, it may be desirable to significantly extend the treatment period, such as when several days (2, 3, 4, 5, 6, or 7) to several weeks (1, 2, 3, 4, 5, 6, 7, or 8) pass between each administration. In other situations, it may be desirable to shorten the time between administrations, with both therapeutic agents administered within seconds or minutes to hours, preferably within approximately 6 hours of each other, and more preferably within approximately 1 or 3 hours. Combination therapies used in the therapeutic methods of the present invention may include the use of various classes of antibiotics, typically at least two different classes of antibiotics. This includes combinations of administering two or three antibiotics simultaneously. Antibiotics commonly used to treat sepsis include aminoglycosides, macrolides, beta-lactams (penicillin, first-, second-, third-, and fourth-generation cephalosporins, carbapenems, etc.), glycopeptides, lincosamides, and / or fluoroquinolones. For example, to cover a broad spectrum, beta-lactams (such as third- or fourth-generation cephalosporins) in combination with macrolides, fluoroquines, or aminoglycosides are commonly used.

[0061] The term "therapeutic dose" refers to the amount of O antigen required to give the intended therapeutic effect to a subject, the amount of which varies depending on the route of administration, the state of infection or sepsis, and the possibility of other therapeutic agents or excipients being included. The methods and uses of the present invention are for patients who need them. The compositions and methods of the present invention are for subjects or patients who need them. The term "patients who need them" refers to a person who has sepsis or is suspected of having developed sepsis. The term "prevention of sepsis" means preventing or suppressing the development of sepsis in a patient with a blood infection, preventing or suppressing the development of severe sepsis in a patient with sepsis, or preventing or suppressing the development of septic shock in a patient with severe sepsis.

[0062] To carry out the method of the present invention, the O antigen may be administered orally, parenterally, by inhalation spray, topically, rectally, nasally, buccally, vaginally, or via an implanted reservoir. As used herein, the term “parenteral” includes subcutaneous, intradermal, intravenous, intramuscular, intra-articular, intra-arterial, intra-bursal, intrasternal, intraspinal, intralesional, and intracranial injection or infusion techniques. Sterile injection compositions, such as sterile aqueous or oily suspensions for injection, can be formulated according to techniques known in the art using appropriate dispersants or wetting agents (e.g., Tween 80) and suspending agents. Sterile injections may also be sterile injection solutions or suspensions in non-toxic, parenterally acceptable diluents or solvents, such as 1,3-butanediol solution. Available excipients and solvents include mannitol, water, Ringer's solution, and isotonic sodium chloride solution. Sterile fixative oils are also conventionally used as solvents or suspending agents (e.g., synthetic monoglycerides or diglycerides). Fatty acids, such as oleic acid and its glyceride derivatives, as well as naturally occurring pharmaceutically acceptable oils such as olive oil and castor oil, particularly their polyoxyethylated versions, are useful in the preparation of injectable formulations. These oil solutions or suspensions may also contain long-chain alcohol diluents or dispersants, or carboxymethylcellulose or similar dispersants. Other commonly used surfactants, such as Tweens or Spans, commonly used in the manufacture of pharmaceutically acceptable solids, liquids, or other dosage forms, or other similar emulsifiers and bioavailability enhancers, may also be used for formulation purposes.

[0063] Compositions for oral administration may be, but are not limited to, any orally acceptable dosage form, such as capsules, tablets, emulsions, aqueous suspensions, dispersions, or solutions. For oral tablets, commonly used carriers include lactose and corn starch. Lubricants such as magnesium stearate are also commonly added. For oral administration in capsule form, useful diluents include lactose and dried corn starch. When aqueous suspensions or emulsions are administered orally, the active ingredient can be suspended or dissolved in the oil phase in combination with an emulsifier or suspending agent. Specific sweeteners, flavorings, or colorings may be added as needed. Nasal aerosols or inhalation compositions can be prepared according to well-known techniques in the field of pharmaceutical formulation. Compositions containing fused polycyclic compounds may also be administered in the form of suppositories for rectal administration. The carriers in the pharmaceutical composition must be "acceptable" in the sense that they are compatible with the active ingredient of the formulation (preferably, they can stabilize the active ingredient) and must not be harmful to the target of treatment. For example, one or more solubilizers that form a more soluble complex with a fusion polycyclic compound, or more solubilizers, can be used as a pharmaceutical carrier for delivering the active compound. Other examples of carriers include colloidal silicon dioxide, magnesium stearate, sodium lauryl sulfate, and D&C Yellow #10.

[0064] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0065] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0066] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0067] In another embodiment, an O antigen is provided for use in the treatment of a bacterial infection, which mobilizes TpMos from the bone marrow to the peripheral blood of the target.

[0068] In one embodiment, the bacterial infection is bacterial sepsis.

[0069] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0070] In one embodiment, the O antigen includes the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0071] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0072] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0073] In one embodiment, the O antigen is used as an adjunctive therapy.

[0074] In one embodiment, a method is provided for treating a bacterial infection, comprising administering to a subject a composition containing a therapeutically effective amount of O antigen, wherein the administration of O antigen mobilizes migratory promonocytes (TpMos) from the subject's bone marrow into the peripheral blood.

[0075] In one embodiment, the bacterial infection is bacterial sepsis.

[0076] In one embodiment, the O antigen is an antigen derived from Escherichia coli.

[0077] In one embodiment, the O antigen includes the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0078] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0079] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0080] In one embodiment, the amount of O antigen present in the composition is 40 ng to 400 ng.

[0081] In one embodiment, the O antigen is used as an adjunctive therapy.

[0082] One embodiment provides a method for recruiting pre-transition monocytes (TpMos) from the bone marrow of a subject into the peripheral blood, the method comprising administering a therapeutically effective dose of O antigen to the subject.

[0083] In one embodiment, the therapeutically effective dose of O antigen is 40 ng to 400 ng.

[0084] In one embodiment, the O antigen is an O antigen derived from Escherichia coli.

[0085] In one embodiment, the O antigen includes the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

[0086] In one embodiment, the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

[0087] In one embodiment, the E. coli O18 serotype is E. coli UTI89 strain.

[0088] In another embodiment, a method is provided for determining the prognosis of a subject having sepsis caused by a Gram-negative bacterial infection, the method comprising detecting the presence of migratory promonocytes (TpMos) in a blood sample taken from the subject, the presence of TpMos in the blood sample indicating a favorable clinical outcome. In a therapeutic context, “favorable clinical outcome” may mean that treatment is possible.

[0089] The term “prognosis” means predicting the expected course and outcome of a clinical condition or disease. The term “prognosis” does not refer to the ability to predict the course or outcome of a disease with 100% accuracy. Instead, the term “prognosis” refers to the probability that a particular course or outcome will occur in a subject exhibiting a particular condition compared to an individual exhibiting no particular condition. “Prognosis” can be made with respect to one or more clinical outcomes, such as the rate of disease progression in a subject, the severity of the disease, the survival rate, the length of survival, or the response to therapeutic intervention. Examples of “favorable clinical outcomes” include recovery from the disease, disease-free survival after recovery from the disease, a reduced likelihood of disease recurrence, slower disease progression, reduced disease severity, improved survival rate, extended length of survival, and a positive response to therapeutic intervention in the subject.

[0090] In one embodiment of this disclosure, administration of a specific O antigen glycan structure mobilizes TpMos into the circulatory system, where it performs TpMo effector functions such as replenishing lost macrophages. This glycan structure remains intact on the O antigen structure of LPS. The presence of TpMos suggests bacterial infection by a bacterial strain possessing the specific O antigen glycan structure. However, due to the protective functions of TpMos, such as acting as a source of macrophage replenishment and balancing pro-inflammatory cytokine responses, the presence of TpMos is beneficial in mitigating bacterial infections caused by both Gram-positive and Gram-negative bacteria.

[0091] In one embodiment, TpMo recruitment helps modulate the immune response to bacterial infections and sepsis by rapidly replacing the resident macrophage pool depleted by bacterial-induced cell death and attenuating cytokine storms induced by inflammatory monocytes.

[0092] In one embodiment, the O antigen may alter the immune response associated with sepsis by supporting macrophage survival at the site (by recruiting TpMos into the circulatory system). As a result, suppression of bacterial infection is enhanced and the inflammatory response is reduced.

[0093] O antigen can be used as an adjunctive therapy. Ideally, O antigen should be administered in the early stages of sepsis or immediately after diagnosis, in conjunction with other primary treatments. Examples of primary / first-line treatments include antibiotic therapy, intravenous fluid or vasoconstrictor administration, and corticosteroid therapy.

[0094] In one embodiment, recruited TpMos and TpMo-derived macrophages may increase IL-10 production in subjects with sepsis. IL-10 production may increase in the early stages of sepsis as one of the defense mechanisms.

[0095] TpMos can be used as a biomarker for sepsis and to assess the prognosis of sepsis patients. The presence of TpMos improves sepsis survival and therefore indicates favorable clinical outcomes. This is evident from the data obtained from the setup shown in Figure 17. Some sepsis patients in the ICU have TpMos in circulation. Patients without TpMos in circulation deteriorated after some time, but patients who were able to be discharged (i.e., recovered or achieved favorable clinical outcomes) had TpMos in circulation.

[0096] The inventions described herein as exemplary can be adequately implemented even without any elements or limitations not specifically disclosed herein. Therefore, terms such as “including,” “containing,” and “containing” should be interpreted broadly and without limitation. Furthermore, the terms and expressions used herein are for illustrative purposes only, not limitation, and the use of such terms and expressions is not intended to exclude equivalents of any or any of the illustrated and described features, although it should be recognized that various modifications are possible within the scope of the claimed invention. Therefore, while the inventions are specifically disclosed by preferred embodiments and optional features, it should be understood that modifications and changes to the inventions disclosed herein are implementable by those skilled in the art, and such modifications and changes are considered to be within the scope of the invention.

[0097] The present invention is described extensively and comprehensively herein. Each of the narrower groups of species and subgenera included within the scope of the comprehensive disclosure also constitutes part of the invention. This includes the general description of the invention with provisos or negative limitations that remove any subject matter from a genus, regardless of whether the deleted material is specifically described herein.

[0098] Other embodiments are within the scope of the following claims and non-limiting embodiments. Furthermore, where a feature or aspect of the present invention is described in terms of the Markush group, those skilled in the art will understand that the present invention is also described in terms of any individual member or subgroup of a member of the Markush group.

[0099] Materials and methods Tissue preparation for flow cytometry and sorting The submandibular region was incised using a 5-mm lancet, and a total of 200 μl of blood was collected and processed with commercially available red blood cell lysis buffer (eBioscience). Mice were sacrificed by CO2 inhalation. To collect peritoneal cells, 3 ml of PBS containing 2 mM EDTA was administered intraperitoneally using a 26.5-gauge needle. PL was collected, and the cell suspension was passed through a 70-μm nylon mesh. To collect BM cells, the mouse femurs were flushed with PBS containing 2 mM EDTA and 3% fetal bovine serum using a 23-gauge needle, and the effluent was passed through a 70-μm nylon mesh. Antibodies were purchased from eBioscience, Biolegend, BD Biosciences, or R&D Systems. Mouse cells were stained with the following antibodies: CCR2 (475301), CD3e (145-2C11), CD11b (M1-70), CD11c (N418), CD16 / 32 (2.4G2), CD31 (390), CD43 (S7), CD45 (30-F11), CD45.1 (A20), CD45.2 (104), CD45R (B220) (RA3-6B2), CD62L (MEL-14), CD90.2 (53-2.1), CD106 (429 / MVCAM.A), CD115 (AFS98), c-kit (2B8), CXCR4 (2B11), CX3CR1 (SA011F11), F4 / 80 (BM8), I-A / I-E (M5 / 114.15.2), Flt-3 (A2F10), Ly6C (HK1.4), Ly6G (1A8), NK1.1 (PK136), PD-L1 (10F.9G2), Sca-1 (D7), Siglec-F (E50-2440), Tim-4 (54). Dead cells were identified using 4’,6-diamidino-2-phenylindole (DAPI) staining and excluded. Blood and bone marrow monocytes were identified as Lin (B220 / CD90.2 / NK1.1) neg Ly6G neg CD115 pos and. Monocytes were further identified as cMoPs (CD11b neg Ly6C hi ckit pos ), TpMos (CD11b lo Ly6C hi ckit neg CXCR4 hi), and MatMos(CD11b pos Ly6C hi ckit neg CXCR4 lo ) were selected. Total PL macrophages were CD45 pos Lin(B220 / CD90.2 / NK1.1) neg CD11b pos F4 / 80 pos It was identified as follows. To confirm cytokine expression, BM or peritoneal cells were stimulated with LPS at 37°C and 5% CO2 for 3 hours (24 hours for iNOS expression) in the presence of GolgiStop and GolgiPlug (BD Biosciences) in diluted medium according to the manufacturer's instructions; stained with relevant surface markers; fixed with fixation / permeabilization buffer (BD Biosciences), then stained with IL-1β (NJTEN3), IL-6 (MQ213A5), IL-10 (JES5-16E3), TNF-α (MP6-XT22), and iNOS / NOS2 (CXNFT); washed; and acquired by flow cytometry. Cells were acquired using a BD LSR II flow cytometer with FACSDiva software, and the data was subsequently analyzed using FlowJo software (TreeStar). The total number of cells collected was quantified using count beads (CountBright; Life Technologies) according to the manufacturer's protocol. BM TpMos and MatMos were sorted using a BD FACSAria II sorter, achieving a purity of over 98%.

[0100] TpMos and MatMos adoption transplants BM TpMos and MatMos selected from WT or Fucci-474 mice were suspended in 200 μl of PBS and adopted into steady-state or sepsis-induced CD45.1 recipient mice via intravenous or intraperitoneal routes (as shown). Recipient mice were euthanized at specified time points, and blood, BM, and PL were collected, surface-stained, and analyzed by flow cytometry. In intra-BM (IBM) transplantation of BM TpMos and MatMos, selected 5 × 10⁶ mice were used. 5 individual GFP+ TpMos and tdTomato + MatMos was resuspended in a 1:1 ratio, and CD45.2 + The transplant was administered to mice via a single injection. Briefly, recipient mice were anesthetized with ketamine / xylazine and their limbs were shaved before transplantation. Nine hours after bacterial infection, the recipient mice's tibias and blood were collected, surface-stained, and analyzed by flow cytometry.

[0101] Bacterial infection model Escherichia coli (E. coli) strains UTI89, DFB1655L5 (L5), and DFB1655 L9 (L9) were identified by the Singapore Science and Technology Promotion Organisation (A * The samples were provided by Swaine Chen of STAR. Escherichia coli strain MG1655, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, and Enterococcus faecium were provided by Ghee Chuan Lai of A*STAR, Singapore. As preparation for infection, the bacteria were cultured in lysogenic medium (LB) and set to 37°C in a shaking incubator. The bacteria were in the mid-logarithmic growth phase (optical density at 600 nm (OD)). 600 The mice were allowed to grow to 0.4-0.6 and washed twice with phosphate-buffered saline (PBS). The mice were then fed 1 × 10¹⁶ mice in 200 μL of PBS. 6 Colony-forming units (CFUs) of Escherichia coli were administered intraperitoneally. The control group received 200 μL of PBS intraperitoneally. Mice were collected 9 or 18 hours post-infection. E. coli levels were measured by collecting peritoneal fluid 18 hours post-infection, diluting it accordingly, and culturing it overnight on LB plates. Colonies were counted, and CFUs were calculated the following day. Bar graphs were plotted as CFUs per microliter of ascites fluid.

[0102] CLP-induced sepsis The experimental procedure was carried out as described above (Rittirsch et al., 2009, Nature Protocols). Under ketamine / xylazine anesthesia, the abdominal cavity was exposed and the cecum was brought outside the body. For moderate and severe sepsis, 50% and 75% cecal ligation were performed using non-absorbable 7-0 sutures, respectively. The distal end of the cecum was perforated using a 26.5 gauge needle, and a small amount of feces was pushed out through the perforation and returned to the abdominal cavity. The peritoneum was closed, and saline and buprenorphine were subsequently administered by subcutaneous injection. A sham control group matched for age and sex was included in all procedures.

[0103] BrdU pulse and growth assay Mice were administered 1.5 mg of BrdU (BD Biosciences) by intraperitoneal injection over 30 minutes, and their proliferative capacity was evaluated. To detect BrdU uptake, cells were surface-stained, fixed, and permeabilized. Intracellular staining was performed with fluorescein isothiocyanate or late-stage promoting complex-conjugated anti-BrdU antibody according to the manufacturer's protocol (Brd UFlow kit, BD Biosciences), followed by analysis by flow cytometry. A Fucci genetically modified mouse model, in which cells in the S-G2-M phase of the cell cycle are labeled with a green-emitting fluorescent protein, was also used to identify proliferating cells by flow cytometry. [Examples]

[0104] Non-limiting examples and comparative examples of the present invention will be described in further detail by reference to specific embodiments, but this should not be construed as limiting the scope of the invention in any way.

[0105] Hereinafter, the entirety of Teh, Ye Chean, et al. “Transitional Premonocytes Emerge in the Periphery for Host Defense Against Bacterial Infections.” Science Advances, vol. 8, no. 9, American Association for the Advancement of Science (AAAS), Mar. 2022 is incorporated herein by reference.

[0106] Example 1 Tissue-resident macrophages (TRMs) function as early immune sentinels for host defense. However, they are susceptible to cell death during inflammation and infection. In sterile conditions, the temporary loss of TRMs does not immediately pose a danger to the host. However, in the presence of pathogenic bacteria, if these cells are not effectively replaced in a niche composed of dying macrophages, host morbidity is likely to increase. Therefore, to protect against these rapidly replicating bacteria, monocytes need to be rapidly mobilized into available niches. Monocytes not only serve as emergency reservoirs for macrophages but can also reduce the bacterial load by performing effector functions such as phagocytosis and cytokine production. However, the performance of monocyte effector functions often leads to monocyte depletion and subsequent cell death, limiting their ability to differentiate into macrophages in such scenarios.

[0107] The inventors have elucidated the different roles of monocyte subsets in bacterial infections and sepsis, and highlighted a novel protective response of TpMos against peripheral bacterial infections. Specifically, in the circulatory system of mice infected with E. coli and developing CLP-induced sepsis, Ly6C hiA population of proliferative monocytes was detected (Figure 1A-C). UMAP analysis and transplantation experiments confirmed that these proliferative monocytes were bone marrow (BM)-derived TpMos (Figure 1D-F). Subsequently, TpMos invaded inflamed tissues, re-forming empty niches left behind after TRM death during bacterial infections and sepsis. TpMos act as progenitor cells that replenish the macrophage pool during severe inflammation caused by bacterial infections, and can also perform effector functions. They were found to have low inflammatory response to CSF-1 signaling and low sensitivity to apoptosis (Figure 2A, B). Importantly, TpMos may provide a protective effect in septic mice by balancing pro-inflammatory responses associated with cytokine storms (Figure 2C).

[0108] Example 2 We investigated whether TpMos are recruited under other inflammatory conditions. Interestingly, TpMos were detected only under bacterial exposure (Figure 3A) and not in tested parasitic or viral infection models such as malaria (Figure 3B), influenza (Figure 3C), dengue fever, and Zika fever (Figure 3D). TpMo recruitment was not detected in non-infectious settings such as high-fat diet models (Figure 3E) or pregnancy models (Figure 3F).

[0109] Example 3 Since TpMos was detected only in the circulating blood of mice exposed to the bacteria, we then investigated whether specific bacterial characteristics triggered TpMos release. It has been reported that a mixture of bacteria is often found in blood cultures of sepsis patients. Our CLP-induced sepsis model mimics human polybacterial sepsis, as it relies on bacteria in the mouse cecum to induce an inflammatory state. However, the mouse microbiome contains diverse bacteria, and different bacterial species and components are clearly recognized by the host. Because the mouse microbiome contains a mixture of Gram-positive and Gram-negative bacteria, the inventors wanted to investigate whether all bacteria are involved in inducing TpMo efflux. Interestingly, among the bacteria examined, only Gram-negative E. coli induced a significant amount of TpMos into the circulating system (Figure 4A). This suggests that their recruitment was triggered by a signal limited to Gram-negative bacteria.

[0110] To clarify the specific factors causing this phenomenon, the inventors investigated lipopolysaccharide (LPS), which constitutes the main component of the cell wall of Gram-negative bacteria. LPS is composed of lipid A, core oligosaccharide, and O-polysaccharide (O antigen). Interestingly, TpMos was recruited only upon infection with E. coli serotype O18 (UTI89). Laboratory strain E. coli MG1655, which lacks the ability to synthesize the O antigen, could not induce TpMos recruitment even after restoring the wild-type O16 structure with different doses (L5: partial recovery, L9: complete recovery) (Figure 4B). It was also confirmed that TpMo recruitment was limited to O antigen serotypes, and the presence of these cells was not detected even with administration of LPS alone. However, LPS from O111 serotype was able to recruit TpMos, while LPS from O55 serotype was not (Figure 4C). This is despite the fact that both serotypes are documented as enteropathogenic strains. Preliminary analysis of the O antigen structures of O18 and O111, which induced the most TpMos into the circulatory system, revealed a common glycan structure, as shown in Figure 4D, suggesting that a specific O antigen glycan structure can induce the release of TpMos into the circulatory system.

[0111] In summary, the data from this study demonstrate that TpMos plays a protective role in bacterial infections and sepsis, and that its recruitment is specifically induced by Gram-negative bacteria possessing a particular O antigen glycan structure. This suggests the potential to improve patient outcomes by utilizing the O antigen as an adjuvant or intervention strategy to recruit TpMos during sepsis.

[0112] Example 4 To determine whether TpMos could potentially be used as a biomarker for sepsis outcomes, blood samples were taken from sepsis patients in the ICU to confirm the presence of TpMos. Preliminary data showed that patients without circulating TpMos deteriorated after some time, while some patients who were discharged still had circulating TpMos (see Figure 17). This suggests that the presence of TpMos indicates a favorable clinical outcome and demonstrates the potential of TpMos as a biomarker for sepsis outcomes. TpMos is not present in the circulating blood of healthy patients and is only present in the bone marrow in a steady state. Therefore, a circulating amount of TpMos greater than zero during bacterial infection / sepsis indicates a favorable clinical outcome for sepsis patients.

[0113] While embodiments of the present invention have been specifically shown and described with reference to certain embodiments, it will be understood by those skilled in the art that various modifications in form and detail are possible without departing from the scope of the invention as defined by the appended claims. Accordingly, the scope of the invention is indicated by the appended claims, and all modifications within the meaning and equivalence of the claims are intended to be encompassed.

Claims

1. The use of O antigen in the manufacture of a drug for treating a bacterial infection, wherein the administered drug mobilizes migratory promonocytes (TpMos) from the bone marrow to the peripheral blood of the target.

2. The use according to claim 1, wherein the bacterial infection is bacterial sepsis.

3. The use according to claim 2, wherein the O antigen is an O antigen derived from Escherichia coli.

4. The use according to any one of claims 1 to 3, wherein the O antigen comprises the structure DGlc-(α1-4)-DGal-(α1-3)-DGlcNAc.

5. The use according to any one of claims 1 to 4, wherein the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

6. The use according to claim 5, wherein the E. coli O18 serotype is strain UTI89 of E. coli.

7. The use of the drug as an adjunct treatment, according to any one of claims 1 to 6.

8. A pharmaceutical composition comprising (a) a therapeutically effective amount of an O antigen containing the structure DGlc-(α1-4)-DGal(α1-3)-DGlcNAc, and (b) one or more pharmaceutically acceptable carriers and / or diluents.

9. The pharmaceutical composition according to claim 8, wherein the O antigen is an O antigen derived from Escherichia coli.

10. The pharmaceutical composition according to claim 8 or 9, wherein the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

11. The pharmaceutical composition according to claim 10, wherein the Escherichia coli O18 serotype is strain UTI89 of Escherichia coli.

12. An O antigen for use in the treatment of bacterial infections, which mobilizes TpMos from the target bone marrow to the peripheral blood.

13. The O antigen according to claim 12, wherein the bacterial infection is bacterial sepsis.

14. The O antigen according to claim 12 or 13, wherein the O antigen is an O antigen derived from Escherichia coli.

15. The O antigen according to any one of claims 12 to 14, comprising the structure DGlc-(α1-4)-DGal(α1-3)-DGlcNAc.

16. The O antigen according to any one of claims 12 to 15, wherein the O antigen is derived from Escherichia coli O18 serotype or O111 serotype.

17. The O antigen according to claim 16, wherein the O18 serotype of Escherichia coli is strain UTI89 of Escherichia coli.

18. The O antigen according to any one of claims 12 to 17, wherein the O antigen is used as an adjunctive therapy.

19. A method for treating a bacterial infection, comprising administering to a subject a composition containing a therapeutically effective amount of O antigen, wherein the administration of the O antigen mobilizes migratory promonocytes (TpMos) from the bone marrow to the peripheral blood of the subject.

20. The method according to claim 19, wherein the bacterial infection is bacterial sepsis.

21. The method according to claim 19 or 20, wherein the O antigen is an O antigen derived from Escherichia coli.

22. The method according to any one of claims 19 to 21, wherein the O antigen comprises the structure DGlc-(α1-4)-DGal(α1-3)-DGlcNAc.

23. The method according to any one of claims 19 to 22, wherein the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

24. The method according to claim 23, wherein the E. coli O18 serotype is strain E. coli UTI89.

25. The method according to any one of claims 19 to 24, wherein the amount of O antigen present in the composition is 40 ng to 400 ng.

26. The method according to any one of claims 19 to 25, wherein the O antigen is used as an adjunctive therapy.

27. A method for recruiting migratory promonocytes (TpMos) from the bone marrow of a target subject into the peripheral blood, comprising administering a therapeutically effective amount of O antigen to the subject.

28. The method according to claim 27, wherein the therapeutically effective amount of the O antigen is 40 ng to 400 ng of the O antigen.

29. The method according to claim 27 or 28, wherein the O antigen is an O antigen derived from Escherichia coli.

30. The method according to any one of claims 27 to 29, wherein the O antigen comprises the structure DGlc-(α1-4)-DGal(α1-3)-DGlcNAc.

31. The method according to any one of claims 27 to 30, wherein the O antigen is an O antigen derived from Escherichia coli O18 serotype or O111 serotype.

32. The method according to claim 31, wherein the E. coli O18 serotype is strain E. coli UTI89.

33. A method for determining the prognosis of a subject having sepsis caused by a Gram-negative bacterial infection, comprising detecting the presence of migratory promonocytes (TpMos) in a blood sample taken from the subject, wherein the presence of TpMos in the blood sample indicates a favorable clinical outcome.

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