Exploring the causal relationship between Takayasu arteritis and inflammatory bowel disease using Mendelian...

Area of Science:

• Genetics
• Immunology
• Gastroenterology

Background:

• Takayasu arteritis (TA) and inflammatory bowel disease (IBD) are distinct conditions with observed co-occurrences.
• The incidence of IBD in TA patients is notably higher than in the general population, suggesting a potential link.
• Mendelian randomization (MR) is a robust method to infer causal relationships by utilizing genetic variants, mitigating confounding and reverse causality.

Purpose of the Study:

• To investigate the potential causal relationship between Takayasu arteritis (TA) and inflammatory bowel disease (IBD) using a two-sample Mendelian randomization analysis.
• To explore whether TA causally influences the risk of developing IBD, including its major subtypes, Crohn's disease (CD) and ulcerative colitis (UC).

Main Methods:

• A two-sample Mendelian randomization (MR) analysis was performed using summary GWAS data for TA and IBD.
• Genetic variants associated with TA were used as instrumental variables to assess their causal effect on IBD risk.
• Sensitivity analyses, including MR-Egger regression, Cochran's Q tests, and leave-one-out analyses, were conducted to assess heterogeneity and pleiotropy.

Main Results:

• While the primary IVW method showed a non-significant trend (OR=1.053, P=0.065) for TA increasing IBD risk, the weighted median (OR=1.038, P=0.002) and weighted mode (OR=1.051, P=0.009) methods indicated a significant harmful causal effect.
• Stratified analysis for Crohn's disease (CD) revealed significant associations with three MR methods, suggesting TA as a risk factor (IVW OR=1.045, P=0.032; weighted median OR=1.028, P=0.021; weighted mode OR=1.031, P=0.022).
• No significant causal effect was observed for TA on ulcerative colitis (UC).

Conclusions:

• This study provides initial evidence suggesting a potential causal role of Takayasu arteritis (TA) in the development of inflammatory bowel disease (IBD).
• Specifically, findings indicate that TA may act as a contributing risk factor for Crohn's disease (CD).
• Further research is warranted to elucidate the underlying mechanisms connecting TA and CD.