Microcystins Exposure and the Risk of Metabolic Syndrome: A Cross-Sectional Study in Central China

Abstract

A growing body of evidence indicates that microcystins (MCs) exposure may cause metabolic diseases. However, studies exploring the effects of MCs exposure on the risk of metabolic syndrome (MetS) in humans are currently lacking, and the underlying mechanisms remain unclear. Here, we conducted a cross-sectional study in central China to explore the effect of serum MCs on MetS, and assessed the mediation effects of the inflammation biomarker, white blood cell (WBC) level, in this relationship. The relationships among MCs and WBC level and risk of MetS were assessed using binary logistic and linear regression. Mediation analysis was used to explore possible mechanisms underlying those associations by employing R software (version 4.3.1). Compared to the lowest quartile of MCs, the highest quartile had an increased risk of MetS (odds ratio [OR] = 2.10, 95% confidence interval [CI]: 1.19, 3.70), with a dose-response relationship (p for trend < 0.05). WBCs mediated 11.14% of the association between serum MCs and triglyceride (TG) levels, but did not mediate the association of MCs exposure with MetS. This study firstly reveals that MCs exposure is an independent risk factor for MetS in a dose-response manner, and suggests that WBC level could partially mediate the association of MCs exposure with TG levels.

Keywords: cross-sectional study; mediation; metabolic syndrome; microcystins.

Figure 1

Odd ratios (ORs) and 95% confidence intervals (CIs) for metabolic syndrome (MetS) risk by quartiles of serum MCs concentration. Adjusted model: adjusting for gender, smoking status, and BMI.

Figure 2

Restricted cubic spline (RCS) plot: relationship between serum MCs levels and MetS risk. The OR of MetS is represented by the solid blue line. Colored part represents the 95% CI. ORs were calculated based on continuous MCs values with adjusting for gender, smoking status, and BMI.

Figure 3

Mediation analysis. Abbreviations: IE, indirect effect; DE, direct effect; TE, total effect. A Non-parametric bootstrap mediation analysis was conducted on the association of serum MCs and TG levels with the mediators of WBC levels, adjusting for gender, smoking status, and BMI. In the mediation relationships, values on the center represent the mediation effect as a proportion of the TE, values on the top represent the IE (95% CI), and values on the bottom indicate the DE (95% CI).