Dissecting Causal Relationship Among Immune Cells, Plasma Metabolites and Coronary Atherosclerosis: A Mendelian Randomization Study.

Background: Circulating immune cells and metabolites are linked to coronary atherosclerosis, but the specific causal relationships and the role of metabolites as mediators remain unclear.

Methods: Summary statistics from GWAS datasets on immune cells (n=3,757), circulating metabolites (n=8,299), and coronary atherosclerosis (cases n=51,589; controls n=343,079) were analyzed using bidirectional Mendelian randomization. Two-step and multivariate Mendelian randomization were employed to identify mediating metabolites, with inverse variance weighting (IVW) as the primary method.

Results: We identified nine immune cell phenotypes, including specific T-cell and monocyte populations, with significant causal links to coronary atherosclerosis. Additionally, 41 plasma metabolites across four metabolic pathways were identified, including 3-hydroxy-2-ethylpropionate and trans-2-hexenoylglycine. Mediation analysis revealed that 3-hydroxy-2-ethylpropionate mediated the effect of IgD+ CD24+ B-cells on coronary atherosclerosis (mediating effect: 0.961; 95% CI: 0.955-0.967), while trans-2-hexenoylglycine regulated IgD+ CD24+ B-cells, showing a mediation ratio of 16.7% (mediating effect: 0.983; 95% CI: 0.981-0.986).

Conclusion: Key immune cell phenotypes and plasma metabolites were linked to coronary atherosclerosis. The roles of 3-hydroxy-2-ethylpropionate and trans-2-hexenoylglycine in regulating B-cell function suggest potential therapeutic targets for prevention and treatment.