Causal relationship between circulating immune cells and inflammatory bowel disease: A Mendelian randomization...

Area of Science:

• Immunology
• Gastroenterology
• Genetics

Background:

• Inflammatory bowel disease (IBD), encompassing Crohn disease and ulcerative colitis (UC), is an immune-mediated condition.
• The precise link between circulating immune cells and IBD pathogenesis remains incompletely understood.
• Understanding these relationships is crucial for developing targeted immunotherapies.

Purpose of the Study:

• To investigate the causal relationship between circulating immune cell phenotypes and IBD, Crohn disease, and UC.
• To identify specific immune cell markers associated with the risk of developing these conditions.
• To explore potential therapeutic targets for IBD based on immune cell profiles.

Main Methods:

• A bidirectional two-sample Mendelian randomization (MR) study was employed.
• Genome-wide association study summary statistics for immune cell phenotypes and IBD traits were utilized.
• Inverse-variance-weighted (IVW) method was the primary analysis, with MR-Egger-intercept tests for pleiotropy and FDR correction.

Main Results:

• No significant causal relationship was found between immune cell phenotypes and IBD or UC after FDR adjustment.
• Four immune cell characteristics were causally associated with Crohn disease.
• Increased HLA-DR+ CD4+ T cells correlated with higher Crohn disease risk; decreased IgD- CD27- B cells, CD28 on CD39+ regulatory T cells, and naive CD4+ T cells correlated with lower risk.

Conclusions:

• Specific immune cell profiles are causally linked to Crohn disease development, but not to UC or general IBD.
• The identified immune cell phenotypes offer potential biomarkers and therapeutic targets for Crohn disease.
• Further research can leverage these findings to advance immunotherapies for IBD.