Human-derived bacterial strains mitigate colitis via modulating gut microbiota and repairing intestinal barrier function in mice

BACKGROUND

Unbalanced gut microbiota is considered as a pivotal etiological factor in colitis. Nevertheless, the precise influence of the endogenous gut microbiota composition on the therapeutic efficacy of probiotics in colitis remains largely unexplored.

RESULTS

In this study, we isolated bacteria from fecal samples of a healthy donor and a patient with ulcerative colitis in remission. Subsequently, we identified three bacterial strains that exhibited a notable ability to ameliorate dextran sulfate sodium (DSS)-induced colitis, as evidenced by increased colon length, reduced disease activity index, and improved histological score. Further analysis revealed that each of Pediococcus acidilactici CGMCC NO.17,943, Enterococcus faecium CGMCC NO.17,944 and Escherichia coli CGMCC NO.17,945 significantly attenuated inflammatory responses and restored gut barrier dysfunction in mice. Mechanistically, bacterial 16S rRNA gene sequencing indicated that these three strains partially restored the overall structure of the gut microbiota disrupted by DSS. Specially, they promoted the growth of Faecalibaculum and Lactobacillus murinus, which were positively correlated with gut barrier function, while suppressing Odoribacter, Rikenella, Oscillibacter and Parasutterella, which were related to inflammation. Additionally, these strains modulated the composition of short chain fatty acids (SCFAs) in the cecal content, leading to an increase in acetate and a decrease in butyrate. Furthermore, the expression of metabolites related receptors, such as receptor G Protein-coupled receptor (GPR) 43, were also affected. Notably, the depletion of endogenous gut microbiota using broad-spectrum antibiotics completely abrogated these protective effects.

CONCLUSIONS

Our findings suggest that selected human-derived bacterial strains alleviate experimental colitis and intestinal barrier dysfunction through mediating resident gut microbiota and their metabolites in mice. This study provides valuable insights into the potential therapeutic application of probiotics in the treatment of colitis.

Erythropoietin-mediated IL-17 F attenuates sepsis-induced gut microbiota dysbiosis and barrier dysfunction

Septic gut damage is critical in the progression of sepsis and multiple organ failure, characterized by gut microbiota dysbiosis and epithelium deficiency in the gut barrier. Recent studies highlight the protective effects of Erythropoietin (EPO) on multiple organs. The present study found that EPO treatment significantly alleviated the survival rate, suppressed inflammatory responses, and ameliorated intestine damage in mice with sepsis. EPO treatment also reversed sepsis-induced gut microbiota dysbiosis. The protective role of EPO in the gut barrier and microbiota was impaired after EPOR knockout. Notably, we innovatively demonstrated that IL-17 F screened by transcriptome sequencing could ameliorate sepsis and septic gut damage including gut microbiota dysbiosis and barrier dysfunction, which was verified by IL-17 F-treated fecal microbiota transplantation (FMT) as well. Our findings highlight the protection effects of EPO-mediated IL-17 F in sepsis-induced gut damage by alleviating gut barrier dysfunction and restoring gut microbiota dysbiosis. EPO and IL-17 F may be potential therapeutic targets in septic patients.

Polyvinyl chloride microplastics induced gut barrier dysfunction, microbiota dysbiosis and metabolism disorder in adult mice

Microplastics (MPs) are a new kind of environmental pollutant that has attracted extensive attention in recent years. MPs can be ingested by multiple organisms and mainly accumulate in the intestine. However, there is still little known about the toxic effects of MPs on humans. Here, we chose the male adult mice as the research model, which were exposed to 2 µm polyvinyl chloride (PVC) MPs at a concentration of 100 mg/kg for consecutive 60 days, to study the toxicity of PVC-MPs. The changes in gut histology, enzymatic biomarkers, the intestinal microbiome, and metabolomic responses were monitored in mice. The results displayed that the PVC-MPs reduced intestinal mucus secretion and increased intestinal permeability. Moreover, PVC-MPs exposure decreased mRNA expression levels of colonic mucus secretion-related genes, indicating dysfunction of intestinal mucus secretion after exposure to PVC-MPs. With regard to the gut microbiota, high throughput sequencing of the full-length 16S rRNA gene sequencing indicated 15 and 17 kinds of gut microbes changed markedly after PVC-MPs exposure at the genus and species level, respectively. Furthermore, marked alterations in the gut microbiome and fecal metabolic profiles were observed, most of which were related to intestinal injury and barrier dysfunction. These results show that exposure to PVC-MPs leads to intestinal injury and changes gut microbiome composition and metabolome profiles, thus the health risk of PVC-MPs to animals needs more concern. This study helps to provide a new idea about the health risk of PVC-MPs to humans.

Enterochromaffin Cells-Gut Microbiota Crosstalk: Underpinning the Symptoms, Pathogenesis, and Pharmacotherapy in Disorders of Gut-Brain Interaction

Disorders of gut-brain interaction (DGBIs) are common conditions in community and clinical practice. As specialized enteroendocrine cells, enterochromaffin (EC) cells produce up to 95% of total body serotonin and coordinate luminal and basolateral communication in the gastrointestinal (GI) tract. EC cells affect a broad range of gut physiological processes, such as motility, absorption, secretion, chemo/mechanosensation, and pathologies, including visceral hypersensitivity, immune dysfunction, and impaired gastrointestinal barrier function. We aim to review EC cell and serotonin-mediated physiology and pathophysiology with particular emphasis on DGBIs. We explored the knowledge gap and attempted to suggest new perspectives of physiological and pathophysiological insights of DGBIs, such as (1) functional heterogeneity of regionally distributed EC cells throughout the entire GI tract; (2) potential pathophysiological mechanisms mediated by EC cell defect in DGBIs; (3) cellular and molecular mechanisms characterizing EC cells and gut microbiota bidirectional communication; (4) differential modulation of EC cells through GI segment-specific gut microbiota; (5) uncover whether crosstalk between EC cells and (i) luminal contents; (ii) enteric nervous system; and (iii) central nervous system are core mechanisms modulating gut-brain homeostasis; and (6) explore the therapeutic modalities for physiological and pathophysiological mechanisms mediated through EC cells. Insights discussed in this review will fuel the conception and realization of pathophysiological mechanisms and therapeutic clues to improve the management and clinical care of DGBIs.

Gut barrier failure biomarkers are associated with poor disease outcome in patients with primary sclerosing cholangitis

AIM

To assess the prevalence of a panel of serologic markers that reflect gut barrier dysfunction in a mixed cohort of pediatric and adult primary sclerosing cholangitis (PSC) patients.

METHODS

Sera of 67 PSC patients [median age (range): 32 (5-79) years, concomitant IBD: 67% and cirrhosis: 20%] were assayed for the presence of antibodies against to F-actin (AAA IgA/IgG) and gliadin (AGA IgA/IgG)] and for serum level of intestinal fatty acid-binding protein (I-FABP) by ELISA. Markers of lipopolysaccharide (LPS) exposure [LPS binding protein (LBP)] and various anti-microbial antibodies [anti-OMP Plus IgA and endotoxin core IgA antibody (EndoCAb)] were also determined. Poor disease outcome was defined as orthotopic liver transplantation and/or liver-related death during the follow-up [median: 99 (14-106) mo]. One hundred and fifty-three healthy subjects (HCONT) and 172 ulcerative colitis (UC) patients were the controls.

RESULTS

A total of 28.4%, 28.0%, 9% and 20.9% of PSC patients were positive for AAA IgA, AAA IgG, AGA IgA and AGA IgG, respectively. Frequencies of AAA IgA and AAA IgG (P < 0.001, for both) and AGA IgG (P = 0.01, for both) but not AGA IgA were significantly higher compared to both of the HCONT and the UC groups. In survival analysis, AAA IgA-positivity was revealed as an independent predictor of poor disease outcome after adjusting either for the presence of cirrhosis [HR = 5.15 (1.27-20.86), P = 0.022 or for the Mayo risk score (HR = 4.24 (0.99-18.21), P = 0.052]. AAA IgA-positivity was significantly associated with higher frequency of anti-microbial antibodies (P < 0.001 for EndoCab IgA and P = 0.012 for anti-OMP Plus IgA) and higher level of the enterocyte damage marker (median I-FABP_{AAA IgA posvsneg}: 365 vs 166 pg/mL, P = 0.011), but not with serum LBP level.

CONCLUSION

Presence of IgA type AAA identified PSC patients with progressive disease. Moreover, it is associated with enhanced mucosal immune response to various microbial antigens and enterocyte damage further highlighting the importance of the gut-liver interaction in PSC.

Bacterial translocation after moderate or major upper abdominal surgery: an analysis of 60 cases

AIM: To investigate the relationship between bacterial translocation and acute systemic inflammatory syndrome (SIRS) in patients who underwent moderate or major upper abdominal operations.

METHODS: Sixty patients who underwent moderate or major upper abdominal operations were observed. Blood samples were collected before surgery and 1, 3, 5 d after surgery to detect plasma D-lactate and isolate genomic DNA. PCR analysis was performed to amplify the β-galactosidase gene of Escherichia coli and 16S rRNA gene. SIRS was monitored in all patients for 10 days.

RESULTS: PCR results were negative in all the patients before operation, while positive PCR results were obtained in 14 patients after surgery. Twelve patients who showed positive PCR results had SIRS (12/14, 85.7%), while only 21.7% of patients (10/46) with negative PCR results had SIRS (P < 0.01). The positive rate of PCR test was significantly higher in patients with SIRS than in those without SIRS [54.5% (12/22) vs 5.3% (2/38), P < 0.01], and in patients undergoing major operations than in those undergoing moderate operations [38.5% (10/26) vs 11.8% (4/34), P < 0.05]. Plasma level of D-lactate was significantly higher in patient with positive PCR results than in those with negative PCR results (5 d: 11.53 mg/L ± 0.68 mg/L vs 5.70 mg/L ± 2.46 mg/L, P < 0.01) and in patients with SIRS than in those without SIRS (5 d: 10.61 mg/L ± 1.77 mg/L vs 5.02 mg/L ± 1.8 mg/L, P < 0.01).

CONCLUSION: Increased intestinal permeability is closely related to bacterial translocation, and bacterial translocation is closely related to SIRS.