Causal association between air pollution and autoimmune diseases: a two-sample Mendelian randomization study

Area of Science:

• Environmental Health
• Immunology
• Genetics

Background:

• Observational studies increasingly link air pollution to autoimmune diseases (ADs).
• Causal evidence for these links remains limited.
• Mendelian randomization (MR) studies have not yet investigated air pollution and ADs.

Purpose of the Study:

• To investigate the potential causal relationships between exposure to particulate matter (PM) and nitrogen oxides (NOx) and various autoimmune diseases.
• To leverage genome-wide association study (GWAS) data for robust causal inference.

Main Methods:

• Utilized GWAS data for PM and NOx from UK Biobank (European and East Asian), Finnish, and Japanese populations.
• Employed two-sample MR analysis, primarily using the inverse variance weighted (IVW) method.
• Conducted supplementary analyses with weighted median, weighted mode, and simple mode methods to ensure robustness and assess pleiotropy.

Main Results:

• In European populations, a significant causal association was found between PM2.5 exposure and psoriasis (OR=3.86).
• Potential associations were observed between PM2.5-10 and vitiligo (OR=7.42), and PM2.5 and systemic lupus erythematosus (OR=68.17).
• No significant causal relationships were identified between air pollutants and systemic lupus erythematosus or rheumatoid arthritis in East Asian populations. No pleiotropy was detected.

Conclusions:

• PM2.5 exposure shows a causal association with psoriasis in European populations.
• Findings suggest that controlling air pollution, specifically PM2.5, may be a viable strategy to mitigate psoriasis development and progression.