Increased activity of lipoprotein-associated phospholipase A2 in non-severe asthma

Abstract

Background: Given increased risk of cardiovascular events in asthma we hypothesized that lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme involved in atherosclerosis, is associated with proinflammatory and prothrombotic blood alterations in this disease. Methods: In 164 adult asthmatics (63 with severe asthma) we measured plasma Lp-PLA2 activity using the PLAC test. We determined its relations to inflammation and prothrombotic blood alterations. Results: In asthma, Lp-PLA2 was inversely related to the age (β = −0.1 [−0.18 to −0.02]) and was lower in women (n = 122 [74%], 205 [182–242] vs. 243 [203–262] nmol/min/ml, p = 0.001). Interestingly, Lp-PLA2 correlated negatively with the asthma severity score (β = −0.15 [−0.23 to −0.07]), being 10.3% higher in those with non-severe (mild or moderate) asthma (n = 101, 62%) as compared to the severe disease subtype (224 [191–261] vs. 203 [181–229], p = 0.006 after adjustment for potential confounders). Lp-PLA2 activity was positively related to the levels of low-density lipoprotein (β = 0.1 [0.02–0.18]), triglycerides (β = 0.11 [0.03–0.19]) and glucose (β = 0.1 [0.02–0.18]) and inversely to the tumor necrosis factor α (β = −0.27 [−0.35 to −0.2]), high sensitivity C-reactive protein (β = −0.1 [−0.19 to −0.02]) and fibrinogen (β = −0.12 [−0.21 to −0.03]), as well as prothrombin (β = −0.16 [−0.24 to −0.08]), and parameters describing thrombin generation potential, such as endogenous thrombin potential (β = −0.14 [−0.21 to −0.06]) and peak thrombin generated (β = −0.2 [−0.28 to −0.12]). Conclusions: Elevated Lp-PLA2 activity in non-severe asthmatics suggests increased atherosclerotic risk in this group. Lower Lp-PLA2 activity accompanied by its inverse relationship to inflammatory or prothrombotic blood biomarkers observed in turn in severe asthmatics might be related to the pathogenesis of more severe asthma phenotype. Keywords: Asthma, Cardiovascular risk, Coagulation, Lipoprotein-associated phospholipase A2, Inflammation