Platelet SR-PSOX/CXCL16–CXCR6 Axis Influences Thrombotic Propensity and Prognosis in Coronary Artery Disease

Platelets express the transmembrane chemokine SR-PSOX/CXCL16, proteolytic cleavage of which generates the sCXCL16 soluble-(s) chemokine. The sCXCL16 engages CXCR6 on platelets to synergistically propagate degranulation, aggregation and thrombotic response. Currently, we have investigated the pro-thrombotic and prognostic association of platelet CXCL16−CXCR6 axis in CAD-(n = 240; CCS n = 62; ACS n = 178) patients. Platelet surface-associated-CXCL16 and CXCR6 surface expression ascertained by flow cytometry correlated significantly with platelet activation markers (CD62P denoting degranulation and PAC-1 binding denoting α2bβ3-integrin activation). Higher platelet CXCL16 surface association (1st quartile vs. 2nd−4th quartiles) corresponded to significantly elevated collagen-induced platelet aggregation assessed by whole blood impedance aggregometry. Platelet-CXCL16 and CXCR6 expression did not alter with dyslipidemia, triglyceride, total cholesterol, or LDL levels, but higher (>median) plasma HDL levels corresponded with decreased platelet-CXCL16 and CXCR6. Although platelet-CXCL16 and CXCR6 expression did not change significantly with or correlate with troponin I levels, they corresponded with higher Creatine Kinase-(CK) activity and progressively deteriorating left ventricular ejection fraction (LVEF) at admission. Elevated-(4th quartile) platelet-CXCL16 (p = 0.023) and CXCR6 (p = 0.030) measured at admission were significantly associated with a worse prognosis. However, after Cox-PH regression analysis, only platelet-CXCL16 was ascertained as an independent predictor for all-cause of mortality. Therefore, the platelet CXCL16−CXCR6 axis may influence thrombotic propensity and prognosis in CAD patients.