Secretory phospholipase A₂-IIA and cardiovascular disease: A mendelian randomization study

Objectives This study sought to investigate the role of secretory phospholipase A₂ (sPLA₂)-IIA in cardiovascular disease. Background Higher circulating levels of sPLA₂-IIA mass or sPLA ₂ enzyme activity have been associated with increased risk of cardiovascular events. However, it is not clear if this association is causal. A recent phase III clinical trial of an sPLA₂ inhibitor (varespladib) was stopped prematurely for lack of efficacy. Methods We conducted a Mendelian randomization meta-analysis of 19 general population studies (8,021 incident, 7,513 prevalent major vascular events [MVE] in 74,683 individuals) and 10 acute coronary syndrome (ACS) cohorts (2,520 recurrent MVE in 18,355 individuals) using rs11573156, a variant in PLA2G2A encoding the sPLA₂-IIA isoenzyme, as an instrumental variable. Results PLA2G2A rs11573156 C allele associated with lower circulating sPLA₂-IIA mass (38% to 44%) and sPLA₂ enzyme activity (3% to 23%) per C allele. The odds ratio (OR) for MVE per rs11573156 C allele was 1.02 (95% confidence interval [CI]: 0.98 to 1.06) in general populations and 0.96 (95% CI: 0.90 to 1.03) in ACS cohorts. In the general population studies, the OR derived from the genetic instrumental variable analysis for MVE for a 1-log unit lower sPLA₂-IIA mass was 1.04 (95% CI: 0.96 to 1.13), and differed from the non-genetic observational estimate (OR: 0.69; 95% CI: 0.61 to 0.79). In the ACS cohorts, both the genetic instrumental variable and observational ORs showed a null association with MVE. Instrumental variable analysis failed to show associations between sPLA ₂ enzyme activity and MVE. Conclusions Reducing sPLA₂-IIA mass is unlikely to be a useful therapeutic goal for preventing cardiovascular events.