Abstract 9880: Microplastics Exposure Promotes Cardiovascular Disease Risk in Mice

Abstract

Microplastics (MPs), particles with a diameter less than 5 mm, have become a common and abundant environmental pollutant. Prior studies suggested exposure to MPs induces oxidative stress and inflammation. As these outcomes also underlie cardiovascular disease (CVD), we sought to determine if ingestion of MPs promotes cardiovascular disease risk. Thus we supplied male C57BL/6J mice (13-weeks old, n=10 in each group) with normal drinking water or that containing two sizes of polystyrene (PS) beads (0.5 μm, 5 μm) at two different doses (0.1 μg/ml and 1 μg/ml) for 12 weeks. At intervals throughout this feeding time course and at termination, we measured several indices of pre-clinical CVD. Compared with control mice, we observed a statistically significant increase in body weight in those mice consuming the 0.5 μm polystyrene beads at a dose of 1 μg/ml as early as 3 weeks after initiation of treatment. This statistically significant increase in mice body weight was maintained after 9-(1.85 fold increase versus control group) and 12-weeks (2.02 fold increase versus control group) of consumption. Furthermore, this increase in body weight appeared to be due to an increase in fat mass. Dual-energy X-ray absorptiometry (DEXA) scan analysis showed that the percent body fat significantly increased in PS exposure groups (control: 13.78±0.17% versus 17.24±0.93% in mice consuming 0.5 μm PS particles at a dose of, 1 μg/ml). In the same group of mice, we also observed an increase in fasting blood glucose (1.46 fold), fasting plasma insulin (2.50 fold), and HOMA-IR scores (2.18 fold) after 12 weeks exposure. Consistently, after analysis of a gene expression array, we found altered expression of some genes regulating adipogenesis and white adipose browning in collected perivascular adipose tissue samples. An analysis of the gut microbiome also identified changes consistent with an increase in adiposity. Thus, our results suggest that polystyrene exposure promotes adiposity and insulin resistance and is a heretofore unrecognized risk factor for atherosclerosis development and CVD.