Biomarker for sepsis encephalopathy and application thereof

Abstract

The invention provides a biomarker for sepsis encephalopathy and application of the biomarker. The biomarker is selected from any one or a combination of more than two of 5-HTP, 5-HIAA or 5-HIAA / 5-HT according to a ratio of 5-HTP to 5-HIAA to 5-HT. The biomarker has the advantages of high sensitivity and high precision, and development and utilization of the key biomarker have important value in precise diagnosis, prognosis, subsequent treatment and drug screening of sepsis encephalopathy.

Description

Technical Field

[0001] The present invention belongs to the field of medical technology, and in particular to a biomarker of septic encephalopathy and a use thereof. Background Art

[0002] Sepsis is a life-threatening organ dysfunction syndrome caused by a dysregulated systemic inflammatory response to infection. The incidence of sepsis is 508.4 cases per 100,000 people, and the overall hospital mortality rate is 32.8%. The central nervous system (CNS) is particularly sensitive to sepsis and may develop sepsis-associated encephalopathy (SAE), which leads to increased mortality (49%) and long-term cognitive dysfunction. SAE is characterized by cognitive problems and a higher risk of neurodegenerative diseases. The pathophysiology of SAE, including neuroinflammation and microglial activation, changes in the blood-brain barrier (BBB), changes in cerebral perfusion and metabolism, etc., is complex and unclear.

[0003] A widely accepted theory is the neurotransmitter and brain metabolism theory. Previous studies have pointed out that inflammatory mediators can cause cholinergic neurotransmission disorders, thereby causing abnormal neuronal function. 5-Hydroxyindoleacetic acid (5-HIAA) is a metabolite of the tryptophan-serotonin pathway that may affect vascular permeability and show significant changes in septic shock. Disorders in serotonin metabolism are thought to affect cognition, behavior, and neurodegenerative diseases. However, how disorders in serotonin metabolism affect the pathological mechanism of SAE remains unknown. In addition, there is still a lack of targeted metabolic studies on SAE patient cohorts. Summary of the invention

[0004] In view of the above problems, the present invention proposes a biomarker for septic encephalopathy based on non-targeted and targeted metabolomics and its use. The present invention includes horizontal and longitudinal patient cohorts, combines animal studies, and analyzes different metabolites through non-targeted and targeted metabolomics to provide a reference for the pathogenesis of septic encephalopathy, and provides a targeted solution for the diagnosis, treatment and prognosis of septic encephalopathy. Specifically,

[0005] In a first aspect of the present invention, a biomarker for septic encephalopathy is provided, wherein the biomarker comprises any one of 5-hydroxytryptophan (5-HTP), 5-hydroxyindoleacetic acid (5-HIAA) or the ratio of 5-hydroxyindoleacetic acid / 5-hydroxytryptamine (5-HIAA / 5-HT) or a combination of two or more thereof.

[0006] Each biomarker described in the present invention can be used alone or in any combination as a basis for the diagnosis of septic encephalopathy.

[0007] Preferably, the biomarker is upregulated in septic encephalopathy samples compared to healthy samples or septic samples.

[0008] Preferably, the sample of the biomarker is derived from blood, urine, saliva, tears, cerebrospinal fluid, lymph or tissue. Further preferably, the sample is derived from blood and / or tissue. More preferably, the blood is plasma.

[0009] In a second aspect of the present invention, a biomarker is provided for use in preparing a diagnostic or prognostic product related to septic encephalopathy or in screening a drug related to the treatment and / or prevention of septic encephalopathy, wherein the biomarker comprises any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT or a combination of two or more thereof, and the 5-HTP and / or 5-HIAA are used as targets for the diagnostic or prognostic product and / or drug.

[0010] Preferably, the biomarker is upregulated in septic encephalopathy samples compared to healthy samples or septic samples.

[0011] Preferably, the sample of the biomarker is derived from blood, urine, saliva, tears, cerebrospinal fluid, lymph or tissue. Further preferably, the sample is derived from blood and / or tissue. More preferably, the blood is plasma.

[0012] Furthermore, the diagnosis or prognosis includes: detecting biomarkers in the sample to be tested; and comparing the expression levels of biomarkers in the sample to be tested and those in a healthy sample or a sepsis sample.

[0013] Preferably, compared with a healthy sample or a sepsis sample, if the expression of the biomarker in the sample to be tested is upregulated, sepsis encephalopathy can be diagnosed, or,

[0014] The prognosis of sepsis or septic encephalopathy can be evaluated, and up-regulated expression of the biomarkers in the test sample means a poor prognosis of septic encephalopathy, or an increased possibility of sepsis progressing to septic encephalopathy.

[0015] Furthermore, the drug screening includes detecting biomarkers in the sample to be tested; and comparing the expression levels of the biomarkers in the sample to be tested before and after the candidate is administered.

[0016] Preferably, the detection of biomarkers is to detect the expression amount of the biomarkers in the sample.

[0017] Candidates with downregulated biomarkers are target candidates as drugs for treating and / or preventing septic encephalopathy.

[0018] The third aspect of the present invention provides a use of a biomarker detection reagent in the preparation of a diagnostic or prognostic product for septic encephalopathy, wherein the biomarker includes any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT, or a combination of two or more thereof.

[0019] Preferably, the sample of the biomarker is derived from blood, urine, saliva, tears, cerebrospinal fluid, lymph or tissue. Further preferably, the sample is derived from blood and / or tissue. More preferably, the blood is plasma.

[0020] Preferably, the detection of biomarkers is to detect the expression amount of biomarkers in the sample.

[0021] Furthermore, the diagnosis or prognosis includes: detecting biomarkers in the sample to be tested; and comparing the expression levels of biomarkers in the sample to be tested and those in a healthy sample or a sepsis sample.

[0022] Preferably, compared with a healthy sample or a sepsis sample, if the expression of the biomarker in the sample to be tested is upregulated, sepsis encephalopathy can be diagnosed, or,

[0023] The prognosis of sepsis or septic encephalopathy can be evaluated, and up-regulated expression of the biomarkers in the test sample means that the prognosis of sepsis or septic encephalopathy is poor, or the possibility of sepsis progressing to septic encephalopathy is increased.

[0024] Preferably, the diagnosis also includes diagnosis in combination with clinical symptoms and / or other test results.

[0025] According to a fourth aspect of the present invention, a diagnostic or prognostic product is provided, wherein the diagnostic or prognostic product comprises a reagent for detecting a biomarker associated with septic encephalopathy, wherein the biomarker is as described in the first aspect.

[0026] Preferably, the detection of biomarkers is to detect the expression amount of biomarkers in the sample.

[0027] Furthermore, the diagnosis or prognosis includes: detecting biomarkers in the sample to be tested; and comparing the expression levels of the biomarkers in the sample to be tested and in a healthy sample or a sepsis sample.

[0028] Preferably, compared with healthy samples or sepsis samples, the biomarker expression in the test sample is upregulated, which can be diagnosed as septic encephalopathy.

[0029] Preferably, the diagnostic or prognostic product comprises a kit or a diagnostic chip.

[0030] Preferably, the diagnosis also includes diagnosis in combination with clinical symptoms and / or other test results.

[0031] Furthermore, the sample is derived from any animal, including humans and non-human animals, wherein non-human animals include all vertebrates, such as mammals and non-mammals, the mammals include non-human primates, mice, rats, guinea pigs, goats, sheep, dogs, rabbits, pigs, cats, cows, and the non-mammals include chickens, amphibians or reptiles;

[0032] Preferably, the sample is derived from a human.

[0033] A fifth aspect of the present invention provides a method for detecting a biomarker of septic encephalopathy, wherein the method comprises using the reagent for detecting the biomarker as described in the fourth aspect.

[0034] A sixth aspect of the present invention provides a method for diagnosing septic encephalopathy, wherein the method comprises detecting the above-mentioned biomarkers in a sample or using the above-mentioned diagnostic product.

[0035] The products described in the present invention include all products related to the diagnosis of septic encephalopathy. Preferably, the products include but are not limited to kits, diagnostic chips, etc.

[0036] In a seventh aspect, the present invention provides a method for screening a drug for treating and / or preventing septic encephalopathy, the screening method comprising:

[0037] (1) Establish disease model;

[0038] (2) administering the candidate to a disease model;

[0039] (3) Detecting the effect of the candidate on biomarkers in disease model samples, wherein the biomarkers include any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT, or a combination of two or more thereof.

[0040] Preferably, the sample of the biomarker is derived from blood, urine, saliva, tears, cerebrospinal fluid, lymph or tissue. Further preferably, the sample is derived from blood and / or tissue. More preferably, the blood is plasma.

[0041] Preferably, the detection of biomarkers is to detect the expression amount of the biomarkers in the sample.

[0042] More preferably, after administration of the candidate, the expression of the biomarker is downregulated, and the candidate is considered to be a target candidate, which can be used as a drug for treating and / or preventing septic encephalopathy.

[0043] Preferably, the screening method further comprises detecting amino acid metabolites and / or neurodegenerative disease and neural injury markers.

[0044] Preferably, the amino acid metabolite comprises β-alanine (Beta-Alanine, Bala).

[0045] Preferably, the neurodegenerative disease and nerve injury markers include glial fibrillary acid protein (GFAP), neurofilament light chain (NFL) and / or recombinant ubiquitin carboxyl terminal hydrolase L1 (UCHL1).

[0046] Preferably, if after administration of the candidate, amino acid metabolites and / or neurodegenerative disease and neural injury markers undergo synergistic changes, the candidate is considered to be a target candidate and can be used as a drug for treating and / or preventing septic encephalopathy.

[0047] In an eighth aspect, the present invention provides a drug for treating and / or preventing septic encephalopathy, wherein the drug targets 5-HTP and / or 5-HIAA, and the drug downregulates 5-HTP and / or 5-HIAA.

[0048] Preferably, the drug also causes synergistic changes in the expression of neurodegenerative disease and neural injury markers.

[0049] Preferably, the neurodegenerative disease and nerve injury markers include GFAP, NFL and / or UCHL1.

[0050] Preferably, the drug also causes a synergistic change in the expression of amino acid metabolites, and the amino acid metabolites include Bala.

[0051] In an eighth aspect, the present invention provides an inhibitor of tryptophan metabolism for use in the preparation of a pharmaceutical composition for preventing and / or treating septic encephalopathy, wherein the inhibitor of tryptophan metabolism inhibits the expression of tryptophan metabolites, and the tryptophan metabolites include any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT, or a combination of two or more thereof.

[0052] Preferably, the inhibitor also causes synergistic changes in the expression of neurodegenerative disease and neural injury markers.

[0053] Preferably, the neurodegenerative disease and nerve injury markers include GFAP, NFL and / or UCHL1.

[0054] Preferably, the inhibitor also causes a synergistic change in the expression of amino acid metabolites, wherein the amino acid metabolites include Bala.

[0055] The septic encephalopathy described in the present invention includes but is not limited to septic encephalopathy combined with other diseases. Preferably, the other diseases include but are not limited to hypertension, diabetes, etc.

[0056] The term "include" or "comprising" in the present invention is an open description containing the specified components or steps described, and other specified components or steps that will not be substantially affected.

[0057] The present invention discloses biomarkers of septic encephalopathy and common and unique diagnostic and prognostic products thereof, and screens out key biomarkers that change significantly in patients with septic encephalopathy, wherein the common key biomarkers include 5-HTP, 5-HIAA or 5-HIAA / 5-HT. The key biomarkers can be used for the diagnosis and prognosis of septic encephalopathy, and have the advantages of high sensitivity and strong specificity, and can effectively distinguish septic encephalopathy from healthy people and septic patients. The development and utilization of key biomarkers will provide new ideas and methods for the accurate diagnosis and subsequent treatment of septic encephalopathy. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 :Schematic diagram of this application research.

[0059] Figure 2 : Flowchart of patient cohort composition, inclusion, exclusion, and subgroups, SAE stands for septic encephalopathy.

[0060] Figure 3 : Changes of various cytokines, the ordinate is the expression level of each cytokine in pg / mL, where GCSF = granulocyte colony stimulating factor, IFN-γ = interferon-γ, IL = interleukin, MCP-1 = monocyte chemoattractant protein-1, MIP-β = macrophage inflammatory protein, TNF-α = tumor necrosis factor-α.

[0061] Figure 4: Changes of nerve injury-related factors, the ordinate is the expression level of each nerve injury-related factor in pg / mL, among which BDNF: brain-derived neurotrophic factor; Cathepsin: cathepsin; GFAP: glial fibrillary acidic protein; MPO: myeloperoxidase; NCAM: neural cell adhesion molecule; NFL: neurofilament light chain protein; PAI-1: plasminogen activator inhibitor-1; PDGF: platelet-derived growth factor; PDGF-AA: platelet-derived growth factor-AA; RANTES: regulatory factor expressed and secreted by activated T cells; sICAM-1: soluble intercellular adhesion molecule-1; sVCAM-1: soluble vascular cell adhesion molecule-1; Tau: Tau protein; UCHL1: ubiquitin carboxyl-terminal hydrolase L1.

[0062] Figure 5 :The results of non-targeted metabolomics KEGG enrichment analysis revealed differential metabolites enriched in the tryptophan pathway, (A) between sepsis and healthy controls, (B) between SAE and sepsis non-SAE.

[0063] Figure 6 : Targeted metabolomics showed significant differences in 5-HIAA levels in SAE patients, A: tryptophan; B: 5-HTP; C: 5-HT; D: 5-HIAA; E: 5-HIAA / 5-HT; F: ROC curves of 5-HIAA / 5-HT, GFAP, NfL and UCHL1.

[0064] Figure 7 :Longitudinal cohort and animal experiments verified the differences in 5-HIAA levels in SAE, A: 5-HIAA levels in different clinical stages of humans (sepsis, SAE, SAE recovery, sepsis recovery); B: 5-HIAA levels in plasma of animal models; C: 5-HIAA levels in the prefrontal cortex of animal models.

[0065] Figure 8 : Comparison of 5-HIAA levels in multiple clinical stages.

[0066] Fig. 9 : ROC curves of 5-HT pathway metabolites in diagnosing SAE. DETAILED DESCRIPTION

[0067] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0068] Unless otherwise specified, the materials, reagents, instruments, etc. used in the following examples can be obtained from commercial sources. Example 1 Screening of candidate biomarkers in SAE

[0069] 1 Method

[0070] Specific research methods include Figure 1 shown.

[0071] 1.1 Patient Cohort

[0072] This prospective observational cohort study was conducted in the emergency department of a tertiary care hospital from February 2021 to November 2022. The study was approved by the Ethics Committee of Peking Union Medical College Hospital (PUMCH) (ZS-2165). Sepsis patients were identified according to the Sepsis 3.0 criteria. Exclusion criteria included primary craniocerebral disease, neuropsychiatric diseases with chronic altered consciousness, consciousness disorders caused by primary metabolic disorders, and organ dysfunction. SAE was defined as a Glasgow Coma Scale (GCS) less than 15 or delirium, while the GCS was equal to 15 in the non-SAE group. The control group consisted of healthy volunteers recruited at the PUMCH Physical Examination Center. SAE patients were divided into four clinical subgroups: ischemic-hypoxic type, metabolic type, mixed type, and unclassified type. According to the clinical stage of the patients, they were divided into sepsis stage, SAE stage, SAE recovery stage, and sepsis recovery stage.

[0073] 1.2 Animal experiments

[0074] A sepsis model was established using 8-week-old male and female C57BL / 6 mice by cecal ligation and puncture (CLP). After 24 hours, plasma was obtained by apical puncture under anesthesia, and brain tissue was obtained by perfusion with phosphate-buffered saline (PBS) to isolate the hippocampus and prefrontal cortex. Plasma, hippocampus, prefrontal cortex, and remaining brain tissue were subjected to LC-MS / MS metabolomics analysis. The experiment was approved by the Animal Care and Use Committee of Peking Union Medical College Hospital, Chinese Academy of Medical Sciences (XHDW-2023-078).

[0075] 1.3 Cytokine detection

[0076] This project tested cytokines in some sepsis patients and the control group in order to analyze the inflammatory response and neurological dysfunction characteristics of SAE patients. The following materials were used for testing:

[0077] (1) Luminex liquid suspension chip for cytokine detection

[0078] Detection platform: suspension microbead chip platform Bio-Plex 200 system (Luminex Corporation, Austin, TX, USA)

[0079] Detection Kit I: Bio-Plex Pro Human Cytokine GrpⅠ Panel 17-plex

[0080] Detection factors: G-CSF, IL-6, IL-8, IL-10, MCP-1, MIP-1β, TNF-α

[0081] Test Kit II: MILLIPLEX MAP Human Neurodegenerative Disease MagneticBead Panel 3 Test factors: BDNF, PDGF-AA, RANTES, PDGF, sICAM-1, MPO, NCAM, sVCAM-1, PAI-1, Cathepsin

[0082] (2) Simoa ultrasensitive detection kit for detecting neurotrophic factors

[0083] Test factors: Tau, NFL, GFAP, UCH-L1

[0084] Detection platform: Simoa HD-X AnalyzerTM (Quanterix)

[0085] Detection kit: Simoa Neuro 4-Plex A Kit

[0086] 1.4 Non-targeted / targeted metabolomics based on LC-MS

[0087] Non-targeted and targeted tryptophan metabolite analysis was performed using ultra-high performance liquid chromatography-MS / MS (UHPLC-MS / MS) analysis. The raw data files generated by UHPLC-MS / MS were processed using Compound Discoverer 3.1 (CD3.1, ThermoFisher). These metabolites were annotated using the KEGG database, HMDB database, and LIPIDMaps database. Differentiating metabolites between the two groups were identified by variable projection importance (VIP)>1 and p<0.05.

[0088] 1.5 Statistical analysis

[0089] Data were analyzed and graphed using GraphPad Prism 9.0 and R 4.1.3. For continuous variables, data were presented as mean ± standard deviation (SD). Intergroup comparisons were performed using independent sample t-test and one-way analysis of variance (ANOVA). For non-normally distributed data, median and interquartile range were presented, and intergroup comparisons were performed using Mann-Whitney U test and Kruskal-Wallis test. Categorical variables were presented as number and percentage. p value < 0.05 was considered statistically significant.

[0090] 2 Results

[0091] 2.1 Study Cohort Characteristics

[0092] From February 2021 to November 2022, a total of 218 patients with sepsis were screened, of whom 127 were included in the patient cohort ( Figure 2 ). The control group consisted of 68 healthy volunteers. From February to October 2023, a total of 23 patients participated in the longitudinal cohort study and were divided into four clinical stages according to their clinical course: sepsis stage, SAE stage, SAE recovery stage, and sepsis recovery stage.

[0093] The clinical characteristics of the included cross-sectional cohort patients are shown in Table 1. Compared with male critically ill patients, female patients were more likely to suffer from SAE (42% vs. 63%, p < 0.001). The SAE group had worse clinical manifestations, higher SOFA and APACHE II scores (SOFA 5 vs. 10; APACHE II 15.49 vs. 22.61, p < 0.001), and a higher rate of mechanical ventilation (18% vs. 44%, p = 0.004).

[0094] There are no significant differences in other characteristic indicators.

[0095] Table 1 Basic characteristics

[0096]

[0097]

[0098]

[0099]

[0100]

[0101] APACHE Acute Physiology and Chronic Health Evaluation score, ICU = intensive care unit, IQR = interquartile range, SAE = sepsis-associated encephalopathy, SOFA = sequential organ failure assessment.

[0102] Continuous variables, normal distribution: mean ± standard deviation (Mean ± SD); non-normal distribution: median (IQR)

[0103] Table 2 Cytokines and neurodegenerative factors

[0104]

[0105]

[0106] If the data were missing more than 50%, these data were discarded to avoid bias.

[0107] GFAP = glial fibrillary acidic protein, NFL = neurofilament light chain, Tau = microtubule-associated protein Tau, UCHL1 = recombinant ubiquitin carboxyl-terminal hydrolase L1, BDNF = brain-derived neurotrophic factor, Cathepsin = cathepsin, sICAM1 = soluble intercellular adhesion molecule-1, MPO = myeloperoxidase, PDGFAA = platelet-derived growth factor-AA, NCAM = neural cell adhesion molecule, PDGF = platelet-derived growth factor, sVCAM1 = soluble vascular cell adhesion molecule-1, PAI1 = recombinant plasminogen activator inhibitor-1, NSE = neuron-specific enolase, GCSF = granulocyte colony-stimulating factor, IFN-γ = interferon-γ, IL = interleukin, MCP1 = monocyte chemoattractant protein-1, MIP1β = macrophage inflammatory protein 1β, TNF-α = tumor necrosis factor-α.

[0108] There were no significant differences in plasma cytokines except GFAP, NFL and UCHL1 between the SAE and non-SAE groups ( Figure 3 , Table 2). However, there was a trend of relatively lower levels of common inflammatory cytokines such as IL-6, IL-8, and MCP-1 in the non-SAE group compared with SAE patients. The levels of neurodegenerative disease biomarkers and neural injury markers such as GFAP, NFL, and UCHL1 were significantly higher in the SAE group than in the non-SAE group (non-SAE vs. SAE: GFAP 130.8 vs. 251.4, p = 0.006; NFL 37.3 vs. 129.8, p < 0.001; UCHL1 27.6 vs. 55.6, p < 0.001; Figure 4 , Table 2). 2.2 Analysis of different metabolites enriched in the tryptophan metabolic pathway, especially serotonin metabolism, by non-targeted and targeted metabolomics

[0109] Non-targeted metabolomics analysis was performed on plasma samples from sepsis patients (62 SAE patients, 65 non-SAE patients) and 68 healthy volunteers. A total of 2019 metabolites were identified based on metabolomics. Differential expression analysis showed that the upregulated metabolites were most enriched in amino acid metabolism, especially tryptophan metabolism ( Figure 5 , Table 3).

[0110] Table 3 Expression of each metabolite

[0111]

[0112]

[0113] Kyn = kynurenine, Melatonin = melatonin, Trp = tryptophan, Ach = acetylcholine, Ala = alanine, Arg = arginine, Asp = aspartic acid, Bala = β-alanine, Cys = cysteine, E = epinephrine, GABA = γ-aminobutyric acid, Gln = glutamine, Glu = glutamate, Gly = glycine, Histamine = histamine, L-Dopa = levodopa, Leu = leucine, Lys = lysine, Met = methionine, NE = norepinephrine, Orn = ornithine, Phe = phenylalanine, Ser = serine, Thr = threonine, Tyr = tyrosine, Val = valine, VMA = vanillylmandelic acid.

[0114] To further clarify the differences in metabolite changes in the tryptophan metabolic pathway, targeted tryptophan metabolites were analyzed. Compared with non-SAE patients, SAE patients had significantly higher plasma 5-HTP and 5-HIAA levels (5-HTP: 7.7 vs. 4.9 nmol / L, p<0.001; 5-HIAA: 118.9 vs. 68.7, p=0.03, Figure 6 There was no statistical difference in 5-hydroxytryptamine (5-HT) levels between the SAE and non-SAE groups (1.2 vs. 3.9 nmol / L, p = 0.056, Figure 6 C). The 5-HIAA / 5-HT ratio in the SAE group was significantly increased (p=0.004, Figure 6 E).

[0115] 2.3 Longitudinal follow-up cohort confirmed differences in 5-HIAA metabolism

[0116] (1) A total of 23 sepsis patients participated in the longitudinal cohort study, including 5 patients who developed from sepsis to SAE, 10 patients who had recovered from SAE, and 8 patients who were in the recovery period of sepsis. When the neurological or septic manifestations recovered, the 5-HIAA level decreased (sepsis stage vs. sepsis recovery stage (recovery from the entire sepsis): 64.81nmol / L vs. 29.22nmol / L, p = 0.07; SAE stage vs. SAE recovery stage: 150.69nmol / L vs. 136.17nmol / L, p = 0.88, Figure 7 A in Figure 8 ).

[0117] (2) Animal experiments confirm differences in serotonin metabolism

[0118] To verify the difference in 5-HIAA metabolism in brain tissue, a total of 24 C57BL / 6 mice were divided into CLP group (male = 8, female = 8) and sham operation group (male = 8, female = 8). The 5-HIAA level in mouse plasma showed a similar increase trend as that in humans (CLP vs. sham operation: 354.52 ± 85.04 vs. 273.26 ± 111.83, p = 0.028, Figure 7 In the prefrontal cortex, 5-HIAA levels were higher in the CLP group (1590.36±234.16 vs.1419.56±256.57, p=0.059, Figure 7 (B), while 5-HT level was lower (776.64±277.29 vs. 1176.81±284.15 nmol / L, p<0.001).

[0119] 2.4 Diagnostic value of cytokines and 5-HIAA-related metabolites

[0120] ROC curves were used to evaluate the diagnostic efficacy of GFAP, NFL, UCH-L1, 5-HIAA, 5-HTP, and 5-HIAA / 5-HT in SAE. Figure 6 F in Fig. 9 ).

[0121] The AUC of 5-HIAA for diagnosing SAE was 0.61 (95% CI 0.51-0.71); the cutoff value was 129.72 nmol / L, the sensitivity was 0.42, and the specificity was 0.80.

[0122] The AUC of 5-HTP for diagnosing SAE was 0.64 (95% CI 0.55-0.74); the optimal cutoff value was 1.78 nmol / L, the sensitivity was 0.45, and the specificity was 0.83.

[0123] In this study, a total of 218 participants were included. The metabolic characteristics of SAE patients were explored by detecting cross-sectional cohort pairs. It was found that 5-HIAA had a significant potential harmful role in the progression of SAE. To clarify the dynamic changes of 5-HIAA in the progression of SAE, the 5-HIAA levels in the longitudinal cohort were further analyzed, and it was verified that 5-HIAA increased in the SAE stage. In addition, the sepsis mouse model showed that 5-HIAA levels increased not only in the peripheral circulation system but also in the brain, which may provide new insights into potential SAE biomarkers.

[0124] 5-HIAA levels were evaluated in SAE patients and animal models of sepsis, suggesting that 5-HIAA may be a potential diagnostic factor for SAE. To validate changes in tryptophan metabolism, untargeted metabolomics was further performed. Results showed enrichment of tryptophan metabolic pathways in patients with sepsis. Notably, these changes were more significant in SAE patients than in non-SAE patients. To further identify changes in metabolites, targeted metabolomics were performed in cross-sectional and longitudinal patient cohorts and in the CLP model. Results showed significantly higher 5-HIAA levels in the prefrontal cortex of the sepsis model. Elevated 5-HIAA levels and 5-HIAA / 5-HT ratios may indicate activation of the serotonin pathway. The turnover of 5-HIAA increased in sepsis and SAE progression, suggesting that serotonin metabolism is involved in SAE. 5-HIAA is a metabolite of serotonin and is more stable than serotonin itself, which may explain why 5-HIAA showed more significant differences compared to serotonin and 5-HTP. Previous sepsis studies have shown that 5-HIAA may disrupt the endothelial barrier through the ROCK signaling pathway, indicating that 5-HIAA is a new biomarker for vascular permeability. The above longitudinal 5-HIAA results showed that 5-HIAA levels increased during the progression of sepsis, especially in the SAE stage, which was associated with cognitive function in sepsis.

[0125] Patients with SAE had higher levels of neurodegenerative disease biomarkers and worse clinical outcomes. GFAP, NfL, and UCHL1 levels were significantly higher, suggesting that SAE patients may have brain damage. These biomarkers have been noted in Alzheimer's disease, HIV-associated neuropathy, and blood-brain barrier damage, suggesting that blood-brain barrier integrity is a key factor in the pathophysiology of SAE. After comparing the ROCs of 5-HIAA / 5-HT with UCHL1, GFAP, and NfL, the diagnostic value of 5-HIAA / 5-HT was found to be similar to that of neurodegenerative disease biomarkers.

[0126] The above results show that the serotonin pathway is related to the SAE process. 5-HIAA, as a metabolite of the serotonin pathway, can be used as a marker for SAE, providing a target for the early identification and clinical prognosis of SAE. At the same time, GFAP, NFL, UCH-L1, 5-HT, 5-HTP, and 5-HIAA / 5-HT can also be used as markers for the early identification and clinical prognosis of SAE.

[0127] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A biomarker for septic encephalopathy, characterized in that: The biomarkers include any one or a combination of two or more of 5-hydroxytryptophan (5-hydroxytryptophan, 5-HTP), 5-hydroxyindoleacetic acid (5-HIAA) or the ratio of 5-hydroxyindoleacetic acid / 5-hydroxytryptamine (5-HIAA / 5-HT).

2. Use of a biomarker in preparing a diagnostic or prognostic product related to septic encephalopathy or screening a drug for treating and / or preventing septic encephalopathy, characterized in that: The biomarkers include any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT or a combination of two or more thereof, and the 5-HTP and / or 5-HIAA are used as targets for diagnostic or prognostic products and / or drugs.

3. Use of a biomarker detection reagent in the preparation of a diagnostic or prognostic product for septic encephalopathy, characterized in that: The biomarkers include any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT, or a combination of two or more thereof.

4. The use according to claim 3, characterized in that: The application includes detecting biomarkers in a sample, and the sample is derived from blood, urine, saliva, tears, cerebrospinal fluid, lymph fluid or tissue.

5. The use according to any one of claims 3-4, characterized in that: The detected biomarker is the expression amount of the biomarker in the detection sample.

6. A diagnostic or prognostic product, characterized in that The diagnostic or prognostic product includes a reagent for detecting a biomarker of septic encephalopathy, wherein the biomarker includes any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT or a combination of two or more thereof.

7. A method for screening drugs for treating and / or preventing septic encephalopathy, characterized in that: The screening method comprises: (1) Establish disease model; (2) administering the candidate to a disease model; (3) Detecting the effect of the candidate on biomarkers in disease model samples, wherein the biomarkers include any one of 5-HTP, 5-HIAA or the ratio of 5-HIAA / 5-HT, or a combination of two or more thereof.

8. The screening method according to claim 7, characterized in that The sample is derived from blood, urine, saliva, tears, cerebrospinal fluid, lymph fluid or tissue.

9. Use of an inhibitor of tryptophan metabolism in the preparation of a pharmaceutical composition for preventing and / or treating septic encephalopathy, characterized in that: The inhibitor of tryptophan metabolism inhibits the expression of tryptophan metabolites, and the tryptophan metabolites include any one or a combination of two or more of 5-HTP, 5-HIAA, or the ratio of 5-HIAA / 5-HT.

10. A drug for treating and / or preventing septic encephalopathy, characterized in that: The drug targets 5-HTP and / or 5-HIAA, and the drug downregulates 5-HTP and / or 5-HIAA.

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