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

Objective: Increasing 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.

Methods: The 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.

Results: The expression of OX40L in peripheral monocytes in patients with UA [25.6±5.5 mean fluorescence intensity (MFI)] and AMI (29.4±6.3MFI) were significantly higher than those in patients with SA (10.6±2.8MFI) and controls (11.1±3.5MFI). Both sOX40L and PAPP-A in patients with UA (15.7±4.9ng/mL, 25.4±6.8μg/mL, respectively) and AMI (17.1±5.3ng/mL, 26.3±5.6μg/mL, respectively) were significantly higher than those in patients with SA (3.4±1.4ng/mL, 9.6±2.1μg/mL, respectively) and controls (3.9±1.3ng/mL, 8.5±2.8μg/mL, respectively) (P<0.001). Interestingly, a positive correlation was found between sOX40L, membrane-bound OX40L and serum PAPP-A levels (r(1)=0.54, r(2)=0.51; P<0.0001). Both serum and membrane-bound OX40L and PAPP-A levels significantly correlated with complex coronary stenosis (r(1)=0.56, r(2)=0.55, r(3)=0.40; P<0.001).

Conclusion: PAPP-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.