Association Between Gut Microbiota and Pneumonia Risk: A Systematic Review and Mendelian Randomization

Area of Science:

• Microbiome Research
• Infectious Disease Epidemiology
• Genetic Epidemiology

Background:

• The gut-lung axis is implicated in COVID-19 pathogenesis.
• Gut microbiota composition and metabolites may influence COVID-19 severity.
• Mendelian randomization (MR) offers a tool to investigate causal links.

Purpose of the Study:

• To conduct a meta-analysis of MR studies examining the causal relationship between gut microbiota and COVID-19 severity.
• To identify specific gut microbial taxa and metabolites associated with different strata of COVID-19 severity.

Main Methods:

• Systematic review of MR studies adhering to PRISMA 2020 guidelines.
• Meta-analysis of data from 11 studies (32,748,274 participants; 1,487 SNPs).
• Analysis across four COVID-19 severity strata: susceptibility, infection, hospitalization, and critical disease.

Main Results:

• Specific bacteria like Actinobacteria and Negativicutes were associated with increased COVID-19 susceptibility and severity.
• Protective effects were observed for Oxalobacter and Ruminococcaceae UCG014 against COVID-19 susceptibility.
• Consistent risk factors across severity included Actinobacteria, Negativicutes, and Alloprevotella; Oxalobacter and Parasutterella showed protective effects.

Conclusions:

• Robust evidence supports severity-specific causal effects of gut microbiota on COVID-19 outcomes.
• Identified microbial taxa and metabolites serve as potential biomarkers for risk stratification.
• These findings suggest novel targets for adjuvant therapeutic strategies in COVID-19 management.