Positive correlation between pregnancy-associated plasma protein-A level and OX40 ligand expression in patients with acute coronary syndromes

ObjectiveIncreasing evidence show that serum pregnancy-associated plasma protein-A (PAPP-A) and OX40 ligand (OX40L) expression have been implicated in acute coronary syndromes (ACS). We investigated the relationship between PAPP-A level and OX40L in serum and membrane-bound OX40L in patients with ACS.MethodsThe present study included normal controls (n = 30), patients with stable angina (SA) (n = 60) and patients with ACS, including unstable angina (UA) (n = 50) and acute myocardial infarction (AMI) (n = 30). Serum concentrations of PAPP-A and soluble OX40L (sOX40L) were determined with Elisa, whereas the expression of OX40L on monocytes were analyzed with flow cytometry.ResultsThe expression of OX40L in peripheral monocytes in patients with UA [25.6 ± 5.5 mean fluorescence intensity (MFI)] and AMI (29.4 ± 6.3 MFI) were significantly higher than those in patients with SA (10.6 ± 2.8 MFI) and controls (11.1 ± 3.5 MFI). Both sOX40L and PAPP-A in patients with UA (15.7 ± 4.9 ng/mL, 25.4 ± 6.8 μg/mL, respectively) and AMI (17.1 ± 5.3 ng/mL, 26.3 ± 5.6 μg/mL, respectively) were significantly higher than those in patients with SA (3.4 ± 1.4 ng/mL, 9.6 ± 2.1 μg/mL, respectively) and controls (3.9 ± 1.3 ng/mL, 8.5 ± 2.8 μg/mL, respectively) (P < 0.001). Interestingly, a positive correlation was found between sOX40L, membrane-bound OX40L and serum PAPP-A levels (r1 = 0.54, r2 = 0.51; P < 0.0001). Both serum and membrane-bound OX40L and PAPP-A levels significantly correlated with complex coronary stenosis (r1 = 0.56, r2 = 0.55, r3 = 0.40; P < 0.001).ConclusionPAPP-A level was significantly related to soluble and membrane-bound OX40L in patients with ACS. Enhanced level of serum PAPP-A and sOX40L might represent a prognostic marker for coronary disease activity.