Deficit in blood MAIT cells, altered cytokines and T cell dynamics in patients with coronary artery disease.

OBJECTIVES Coronary artery disease (CAD) is a chronic inflammatory disorder characterized by immune dysregulation and a higher risk of viral infections. Among the immune cells involved, mucosal-associated invariant T (MAIT) cells participate in antimicrobial defense and tissue repair, yet their contribution to CAD has not been clearly defined. METHODS Peripheral blood mononuclear cells and plasma were obtained from patients with CAD and from healthy controls. MAIT cell subsets, conventional T cells, and the SARS-CoV-2 receptors ACE2 and CD147 were analyzed by flow cytometry. Cytokines were quantified using ELISA. Additional in-vitro assays were performed to test whether recombinant SARS-CoV-2 spike proteins could influence cell apoptosis or proliferation. RESULTS The number of circulating MAIT cells was markedly reduced in CAD, most notably within the CD8+ population. In contrast, CD4+ MAIT cells were relatively increased but expressed less CCR5 intensities, suggesting limited migratory ability. Plasma IL-7 concentrations were lower in CAD, while IL-18 and IFN-α2 were higher. These findings indicate a disturbed cytokine environment, especially for MAIT cell activation. CAD samples also showed more CD4+PD-1+ and fewer CD8+CD69+ T cells, pointing toward an exhausted phenotype. IL-18 levels correlated negatively with left-ventricular ejection fraction. Expression of ACE2 and CD147 was similar between groups, and spike-protein exposure did not trigger significant apoptosis or proliferation in vitro. CONCLUSION CAD is associated with loss and functional alteration of MAIT cells, cytokine imbalance, and T-cell exhaustion. Together, these immune changes may weaken antiviral defense mechanisms in the context of viral infections, such as the SARS-CoV-2 infection.