Serum total bile acids within the normal range are inversely associated with inflammatory indices and Gensini score in patients with premature coronary artery disease

Background: Both serum bile acids and inflammation have been reported to be associated with coronary artery disease (CAD). However, whether serum total bile acid (TBA) can influence the extent of atherosclerosis in premature CAD (PCAD) patients by modulating immune-inflammation is unknown. Methods: A total of 631 patients with PCAD were enrolled from the First Affiliated Hospital of Xi'an Jiaotong University. Spearman correlation and logistic/linear regression were used to assess the associations between TBA and mediator/outcome variables. The mediating effect of immune-inflammation in the association of TBA with outcomes was further evaluated. Results: TBA was associated with a decreased risk of first myocardial infarction (MI) and a reduced degree of coronary stenosis in PCAD patients. Moreover, the inverse association between TBA and immune-inflammation was observed. Multivariate linear regression showed that for each unit increase in TBA, neutrophil (NEU) decreased by 0.27×10^9/L (β = -0.27, 95% CI: -0.37, -0.16), systemic inflammation response index (SIRI) decreased by 0.12 (β = -0.12, 95% CI: -0.17, -0.06), systemic immune-inflammation index (SII) decreased by 55.25 (β = -55.25, 95% CI: -85.78, -24.72), and C-reactive protein (CRP) decreased by 0.13 mg/L (β = -0.13, 95% CI: -0.25, -0.02). More importantly, the mediation analysis indicated that NEU, CRP, SII, and SIRI statistically explained the association between the TBA and outcomes. Conclusion: TBA is associated with reduced coronary lesion severity, an association that may be linked to chronic inflammation.