Causal Associations Between Gut Microbiota and Psoriasis: A Mendelian Randomization Study

Area of Science:

• Microbiome research
• Dermatology
• Genetics

Background:

• The gut-skin axis suggests a link between gut microbiota and psoriasis.
• Existing evidence is heterogeneous, and causality is difficult to establish through observational studies.

Purpose of the Study:

• To evaluate potential causal associations between gut microbiota (GM) and psoriasis.
• To investigate the role of GM in psoriatic arthritis (PsA).

Main Methods:

• Two-sample Mendelian randomization (MR) using large-scale GWAS summary datasets.
• Inverse variance weighted (IVW) method as the primary analysis.
• Sensitivity analyses including MR-Egger, weighted median, Cochrane's Q test, MR-Egger intercept test, MR-PRESSO, and leave-one-out analysis.

Main Results:

• Nominal protective roles were found for Bacteroidetes and Prevotella in psoriasis.
• Bacteroidia, Bacteroidales, and Ruminococcaceae UCG002 were nominally associated with lower PsA risk.
• Pasteurellales, Pasteurellaceae, Blautia, Methanobrevibacter, and Eubacterium fissicatena group were nominally associated with increased PsA risk.
• The E. fissicatena group was identified as a risk factor for psoriasis, even after FDR correction.

Conclusions:

• Several nominal causal associations between gut microbiota and psoriasis/PsA were identified.
• The E. fissicatena group is a confirmed risk factor for psoriasis.
• These findings may offer novel therapeutic targets for psoriasis management.