Interleukin-21 - A biomarker of importance in predicting myocardial function following acute infarction?

Introduction: Following acute myocardial infarction (AMI), the acute inflammatory response contributes to wound healing but also to progressive myocardial injury. Interleukin-21 (IL-21) plays a key role in immunoregulation; whether IL-21 is associated with left ventricular (LV) remodelling after AMI is unknown. Methods: Plasma IL-21 concentrations were measured in 100 patients (age 58.9 ± 12.0 years, 77% male) admitted with AMI and LV dysfunction, at baseline (mean 46 h) and again at 24 weeks; cardiac magnetic resonance and measurement of B-type natriuretic peptide, monocyte chemoattractant protein-1, matrix metalloproteinase (MMP)-2, -3, -9, and tissue inhibitor of metalloproteinase (TIMP)-1, -2, -4 occurred at both time-points. Remodelling was defined as change in LV end-systolic volume index (ΔLVESVI). Results: Plasma IL-21 concentration was unchanged over time (48.1 [SD 35.4] pg/mL at baseline vs. 48.8 [61.3] pg/mL at 24 weeks, p = 0.92). Baseline IL-21 correlated significantly with ΔLVESVI (r = 0.30, p = 0.005) and change in LV end-diastolic volume index (r = 0.33, p = 0.003). On multivariate analysis, plasma IL-21 was an independent predictor of remodelling. IL-21 was also significantly associated with higher TIMP-4 concentrations and lower MMP-9 concentrations at baseline. Conclusions: IL-21 predicts adverse remodelling following AMI in patients with LV dysfunction. Whether it plays a direct pathophysiological role in remodelling merits further study.