Association between Plasma Proprotein Convertase Subtilisin/Kexin Type 9 and the Presence of Metabolic Syndrome in a Predominantly Rural-Based Sub-Saharan African Population

Background: The prevalence of metabolic syndrome (MetS) has increased dramatically in low- and middle-income countries. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a major role in low-density lipoprotein receptor degradation, but its relationship with metabolic parameters is still poorly understood. We aimed to investigate the association between plasma PCSK9 and metabolic parameters in a Kenyan cohort. Methods: Total plasma PCSK9 levels were measured in 2016 by an in-house enzyme-linked immunosorbent assay (ELISA) using a polyclonal antibody. The International Diabetes Federation (IDF) 2009 consensus statement criteria were used to assess the presence of MetS. Results: In 1338 Kenyans, 11% of the cohort had ≥3 MetS criteria. Total plasma PCSK9 concentration was significantly higher in subjects with MetS than in the non-MetS group (166.8 ± 4.4 vs. 148.0 ± 1.3, P < 0.0001). A progressive increase in circulating PCSK9 was observed when subjects were stratified according to the number of MetS criteria (<3, 3, 4, or 5) [P of the analysis of variance (ANOVA) <0.0001]. In a model corrected for age, sex, lifestyle factors, and body mass index, PCSK9 concentration was a significant predictor of all MetS criteria taken individually, except for waist circumference. Plasma PCSK9 levels were significantly associated with low-density lipoprotein cholesterol, but the strongest association was seen with triglycerides even after multiple adjustments. Conclusions: The presence of MetS was significantly associated with the PCSK9 concentration. Further studies are needed to provide a molecular connection between PCSK9 and insulin, as well as triglyceride metabolism.