Impact of gut microbiota on liver transplantation

Preoperative Factors Affecting Graft Survival After ABO-incompatible Adult Liver Transplantation

BACKGROUND

Although ABO-incompatible liver transplantation (ABOi LT) has undergone remarkable progress, the prognostic factors are poorly understood. This study aimed to elucidate the preoperative factors affecting graft survival after ABOi LT.

METHODS

Patients who underwent ABOi LT between January 2012 and December 2020 at a single institution in South Korea were retrospectively reviewed. A total of 146 recipients, including 34 patients with graft loss, were analyzed.

RESULTS

In the multivariate Cox proportional hazard model, recipient age (≥55 y; hazard ratio, 2.47; 95% confidence interval, 1.18-5.19; P  = 0.017) and donor ABO type (donor A, hazard ratio, 3.12; 95% confidence interval, 1.33-7.33; P  = 0.009) were significantly associated with an increased risk of graft loss. The most common cause of graft loss was recipient death due to bacterial infection (15/34, 44.1%). Both recipient age and donor ABO type were associated with an increased risk of recipient death due to bacterial infections. The incidence of complications after ABOi LT, including antibody-mediated rejection and diffuse intrahepatic biliary stricture, did not differ according to recipient age or donor ABO type.

CONCLUSIONS

These findings suggest that recipient age and donor ABO type should be considered when preparing for ABOi LT. Careful monitoring and care after transplantation are required for recipients with preoperative risk factors.

Effect of gut microbiota changes on cytokines IL-10 and IL-17 levels in liver transplantation patients

BACKGROUND

Liver transplantation (LT) is a critical intervention for individuals with end-stage liver disease; yet, post-transplant problems, especially infections, graft rejection, and chronic liver disease, are often linked to systemic inflammation. Cytokines, small signaling molecules, significantly influence immune responses during and post-liver transplantation. Nonetheless, the intricate relationships among cytokines, immune responses, and the gut microbiota, especially gut dysbiosis, are still inadequately comprehended. Thus, this study aims to identify the gut microbiota (GM) and determine their relationship to cytokines (IL-17 and IL-10) in LT patients, due to their importance in enhancing the recovery rate.

RESULT

The research included 31 liver transplant (LT) patients from the Gastroenterology Surgical Center at Mansoura University, resulting in the collection of 174 stool and blood samples from all participants. Fourteen bacterial species have been identified in samples collected at three intervals: one week before, one week post, and two weeks post LT. A change in gut microbiota composition was noted, characterized by a rise in potentially pathogenic bacteria such as Enterococci and Enterobacteriaceae (including Escherichia coli and Klebsiella) and a reduction in beneficial bacteria such as Bacteroidetes and Firmicutes. The examination of patient demographic and clinical data revealed no significant correlations between sex, age, or diagnostic categories and gut microbiota composition. The findings of the Multivariate Analysis of Variance (MANOVA) indicated a substantial effect of gut microbiota composition on cytokine levels (IL-10 and IL-17), with all tests producing p-values of 0.001. The assessment of cytokine levels indicated fluctuating variations at several time points following surgery. IL-10 levels in the GM groups exhibited a statistically significant elevation during the second week post-surgery (p = 0.036), suggesting a potential recovery-related anti-inflammatory response. In contrast, IL-17 levels rose in the NI group over time, indicating a transition to a pro-inflammatory condition.

CONCLUSION

This study emphasizes the pivotal role of the gut microbiota in regulating immune responses following transplantation.

Current progress on the microbial therapies for acute liver failure

Acute liver failure (ALF), associated with a clinical fatality rate exceeding 80%, is characterized by severe liver damage resulting from various factors in the absence of pre-existing liver disease. The role of microbiota in the progression of diverse liver diseases, including ALF, has been increasingly recognized, with the interactions between the microbiota and the host significantly influencing both disease onset and progression. Despite growing interest in the microbiological aspects of ALF, comprehensive reviews remain limited. This review critically examines the mechanisms and efficacy of microbiota-based treatments for ALF, focusing on their role in prevention, treatment, and prognosis over the past decade.

Microbiome composition recovery after liver transplantation correlates with initial liver disease severity and antibiotics treatment

Liver transplantation (LT) is crucial for end-stage liver disease, but it is linked to infection risks. Pathobionts, microorganisms potentially harmful under specific conditions, can cause complications posttransplant. Monitoring such pathogens in fecal samples can be challenging and therefore remains underexplored post-LT. This study aimed to analyze the gut microbiome before and after LT, tracking pathobionts and correlating clinical data. The study involved 17 liver transplant recipients, 17 healthy relatives (spouses), and 13 donors. Gut samples collected pretranplantation and posttransplantation underwent bacterial and fungal profiling through DNA sequencing. Quantitative polymerase chain reaction was used to assess microbial load. Statistical analyses included alpha and beta diversity measures, differential abundance analysis, and correlation tests between microbiome and clinical parameters. Microbiome analysis revealed dynamic changes in diversity posttransplant. Notably, high-severity patients showed persistent and greater dysbiosis during the first months post-LT compared with low-severity patients, partly due to an antibiotic treatment pre-LT. The analysis identified a higher proportion of pathogens such as Escherichia coli/Shigella flexneri in high-severity cases posttransplant. Furthermore, butyrate producers including Roseburia intestinalis, Anaerostipes hadrus, and Eubacterium coprostanoligenes were positively correlated with levels of albumin. This study offers valuable insights into post-LT microbiome changes, shedding light on the need for tailored prophylactic treatment post-LT.

Biliary atresia: the role of gut microbiome, and microbial metabolites

Biliary atresia (BA) is a progressive fibroinflammatory disease affecting both the extrahepatic and intrahepatic bile ducts, potentially leading to chronic cholestasis and biliary cirrhosis. Despite its prevalence, the exact mechanisms behind BA development remain incompletely understood. Recent research suggests that the gut microbiota and its metabolites may play significant roles in BA development. This paper offers a comprehensive review of the changing characteristics of gut microbiota and their metabolites at different stages of BA in children. It discusses their influence on the host's inflammatory response, immune system, and bile acid metabolism. The review also explores the potential of gut microbiota and metabolites as a therapeutic target for BA, with interventions like butyrate and gut microbiota preparations showing promise in alleviating BA symptoms. While progress has been made, further research is necessary to untangle the complex interactions between gut microbiota and BA, paving the way for more effective prevention and treatment strategies for this challenging condition.