Mucosal-associated invariant T cells correlate with myocardial ischaemia and remodelling in coronary artery disease.

Objectives: Myocardial ischaemia and remodelling are major contributors to the progression and mortality of coronary artery disease (CAD). Previous studies have shown immune cell alterations in CAD patients, but their characteristics and associations with myocardial ischaemia and remodelling remain unclear. Methods: We compared immune cell changes among patients without CAD, those with CAD and those with CAD and heart failure (HF). Results: We found a progressive reduction in circulating mucosal-associated invariant T (MAIT) cells across the three patient groups. MAIT cells exhibited increased expression of activation markers (CD69 and PD-1) and cytotoxic molecules (such as granzyme B). The features of MAIT cells were correlated positively with worsening clinical indicators of myocardial ischaemia and remodelling, including the Gensini score, cTnI, NT-proBNP, LVEF and E/e'. Additionally, the reduction, activation and cytotoxicity of MAIT cells were associated with indicators of myocardial fibrosis (sST2, Gal-3, PICP and PIIINP), a central pathological mechanism of myocardial remodelling. Finally, we preliminarily explored potential triggers for MAIT cell abnormalities in CAD patients and found that impaired intestinal barrier function and increased circulating bacterial antigens may contribute to these changes. Conclusions: During CAD progression, we observed a decrease in circulating MAIT cells. Enhanced activation and cytotoxicity of MAIT cells are associated with myocardial ischaemia and remodelling in CAD patients with heart failure, potentially triggered by gut microbial leakage. Our findings suggest a novel strategy for monitoring and intervention in disease progression.