Introduction
This study explores potential associations between the gut microbiome and fibrosis in patients with viral hepatitis, using network analysis to reveal correlations between multiple microbes and clinical data. The gut-liver axis plays a crucial role in human health, with weakened tight junctions, increased influx of substances into the liver, and IgA-related immune abnormalities observed in patients with chronic hepatitis and liver cirrhosis. However, the causative bacteria remain elusive. Network analysis can reveal potential biomarkers and therapeutic targets, with the hope of improving patient outcomes.
Aims & Methods
We aimed to elucidate the relationship between fibrosis markers and gut microbiome by constructing networks, analyzing fecal samples and clinical indicators of 145 HCV antibody-positive (HCV group) and 84 HBs antigen-positive (HBV group) patients with chronic liver disease who visited our hospital between June 2016 and April 2021. We identified microbes at the genus level by analyzing DNA from the 16S rRNA region (V3-V4) obtained from fecal samples using the Miseq platform, QIIME2, and Silva database.
Patients were divided into HBV and HCV groups to establish reproducible relationships. We calculated Spearman rank correlation coefficients between relative microbial abundance and clinical data, including BMI, age, albumin , total cholesterol, estimated glomerular filtration rate , AST, ALT,GTP, total bilirubin, hemoglobin, platelet count, Fib4-index, prognostic nutritional index (PNI), and ALBI score. We considered p-values below 0.05 and absolute correlation coefficients above 0.3 as significant correlations, which will help in understanding the complex relationships between fibrosis markers and gut microbiome in patients with viral hepatitis.
Results
Patient backgrounds differed between the HBV group (median age 56.5 years, Fib4-index 1.74, PNI 49.5, ALBI -2.8) and the HCV group (68 years, Fib4-index 3.21, PNI 46.5, ALBI -2.6). We identified 263 microbial genus and 34,453 combinations (263C2). Among these, 1,619 combinations in the HBV group and 4,730 in the HCV group showed significant correlations with over 90% showing positive correlations. There were 586 common combinations between both groups, which were highly likely to be a unique bacterial combination maintained across different patient backgrounds.
We found 85 correlations in the HBV group and 20 in the HCV group in the 3,682 combination between 14 types of clinical data and 263 bacterial genus. Specifically, only Veillonella and Streptococcus demonstrated a positive correlation with Fib4-index and a negative correlation with PNI. Lactobacillus showed a positive correlation with age in common between the HBV and HCV groups . They did not have a direct correlation with age, ALT, AST, or platelet count, suggesting a potential relationship with fibrosis. However, the age-correlated Lactobacillus showed a positive correlation with Veillonella and Streptococcus, indicating a possible secondary relationship. Additionally, Streptococcus, occupying a key position in the network with positive correlations with multiple bacteria, may have a significant influence on these microbes.
Conclusion
We found potential associations between specific gut microbes and fibrosis in viral hepatitis patients. Streptococcus, Veillonella, and Lactobacillus were significant in their relationship with fibrosis markers, with Streptococcus playing a central role in the network. Thhs suggests Streptococcus as a potential biomarker and network analysis as a valuable tool for potential diagnostic and therapeutic applications.
