Genetically determined selenium concentrations and risk for autoimmune diseases.

Area of Science:

• Nutritional epidemiology
• Genetic epidemiology
• Autoimmune disease research

Background:

• Observational studies suggest a link between selenium status and autoimmune disease risk.
• Confounding factors and reverse causality complicate observational findings.
• Mendelian randomization (MR) offers a robust approach to infer causality.

Purpose of the Study:

• To investigate the causal association between selenium concentrations and the risk of common autoimmune diseases.
• Utilize a two-sample MR design to overcome limitations of observational studies.
• Examine the specific risks for systemic lupus erythematosus (SLE), rheumatoid arthritis, and inflammatory bowel disease.

Main Methods:

• Employed a two-sample Mendelian randomization (MR) design.
• Identified genetic instruments for selenium from a GWAS meta-analysis of 9639 European individuals.
• Obtained summary statistics for SLE, rheumatoid arthritis, and IBD from public GWAS databases.
• Applied inverse-variance weighted (IVW) method, with weighted median and likelihood-based methods for sensitivity analysis.
• Assessed heterogeneity and pleiotropy using Cochran Q test and MR-Egger regression.

Main Results:

• Genetically predicted higher selenium levels were associated with a reduced risk of SLE (OR=0.85, 95% CI: 0.77-0.93, P=0.001).
• Sensitivity analyses confirmed the association between selenium and decreased SLE risk.
• No significant associations were found between genetically determined selenium concentrations and the risk of rheumatoid arthritis or inflammatory bowel disease.
• No evidence of heterogeneity, pleiotropy, or outlier SNPs was detected for the SLE analysis.

Conclusions:

• The study suggests a potential protective effect of selenium against systemic lupus erythematosus.
• Further research is needed to understand the biological mechanisms underlying selenium's role in SLE.
• Selenium's role in rheumatoid arthritis and inflammatory bowel disease risk requires further investigation.