Increased soluble programed cell death-ligand 1 is associated with acute coronary syndrome.

BACKGROUND Programmed cell death (PD)-1 and its ligand (PD-L1) plays crucial roles in T-cell tolerance as immune checkpoint. Previous studies reported that increased serum levels of soluble PD-L1 (sPD-L1) reflect myocardial and vascular inflammation. However, little is known about the clinical relationship between sPD-L1 and acute coronary syndrome (ACS). We investigated the relation of sPD-L1 and ACS. METHODS We prospectively measured serum levels of sPD-L1 using a commercially available enzyme-linked immunosorbent assay kit in patients with coronary artery disease (CAD) and continuous non-CAD admitted to Kumamoto University Hospital between December 2017 and June 2019. All malignant diseases, patients who underwent hemodialysis, active collagen diseases, and severe infectious diseases were excluded. RESULTS Totally, 446 CAD patients [ACS, n = 124; chronic coronary syndrome (CCS), n = 322] and 24 non-CAD patients were analyzed. The levels of sPD-L1 were significantly higher in patients with ACS than those both with non-CAD and CCS {ACS, 188.7 (111.0-260.8) pg/mL, p < 0.001 vs. non-CAD [83.5 (70.8-130.4) pg/mL]; and p = 0.009 vs. CCS [144.2 (94.8-215.5) pg/mL], respectively}. Univariate logistic regression analysis identified that sPD-L1 was significantly associated with ACS [odds ratio (OR): 1.459, 95% confidence interval (CI): 1.198-1.778, p < 0.001]. Multivariable logistic regression analysis with nine significant factors identified from the univariate analysis revealed that sPD-L1 was significantly and independently associated with ACS (OR: 1.561, 95% CI: 1.215-2.006, p < 0.001). CONCLUSIONS This is the first clinical study to demonstrate the increased level of sPD-L1 in patients with CAD, and the significant association with ACS.