Compositional alterations of gut microbiota in nonalcoholic fatty liver disease patients: a systematic review and Meta-analysis

Abstract

Background Although imbalanced intestinal flora contributes to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), conflicting results have been obtained for patient-derived microbiome composition analyses. A meta-analysis was performed to summarize the characteristics of intestinal microbiota at the species level in NAFLD patients. Methods Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement, a completed search (last update: December 30, 2020) of databases was performed to identify eligible case-control studies detecting gut microbiota in NAFLD patients. The meta-analysis results are presented as the standard mean difference (SMD) and 95% confidence interval (CI). Bias controls were evaluated with the Newcastle-Ottawa Scale (NOS), funnel plot analysis, and Egger’s and Begg’s tests. Results Fifteen studies (NOS score range: 6–8) that detected the gut microbiota in the stools of 1265 individuals (577 NAFLD patients and 688 controls) were included. It was found that Escherichia , Prevotella and Streptococcus (SMD\u2009=\u20091.55 [95% CI: 0.57, 2.54], 1.89 [95% CI: 0.02, 3.76] and 1.33 [95% CI: 0.62, 2.05], respectively) exhibited increased abundance while Coprococcus , Faecalibacterium and Ruminococcus (SMD\u2009=\u2009−\u20091.75 [95% CI: −\u20093.13, −\u20090.37], −\u20099.84 [95% CI: −\u200913.21, −\u20096.47] and\u2009−\u20091.84 [95% CI, −\u20092.41, −\u20091.27], respectively) exhibited decreased abundance in the NAFLD patients compared with healthy controls. No differences in the abundance of Bacteroides , Bifidobacterium , Blautia , Clostridium , Dorea , Lactobacillus , Parabacteroides or Roseburia were confirmed between the NAFLD patients and healthy controls. Conclusions This meta-analysis revealed that changes in the abundance of Escherichia , Prevotella , Streptococcus , Coprococcus , Faecalibacterium and Ruminococcus were the universal intestinal bacterial signature of NAFLD.