NLRP3 inflammasome is involved in ambient PM2.5-related metabolic disorders in diabetic model mice but not in wild-type mice.

ABSTRACT

AIMS: To explore the role of nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome in ambient fine particulate matter (PM2.5)-related metabolic disorders. METHODS: In this study, the C57BL/6 and db/db mice were exposed to concentrated PM2.5 or filtered air (FA) using Shanghai Meteorological and Environmental Animal Exposure System (Shanghai-METAS) for 12 weeks. Indices of lipid metabolism, glucose metabolism, insulin sensitivity, and protein expression of NLRP3 inflammasome in visceral adipose tissue (VAT) were measured, respectively. RESULTS: The results showed that PM2.5 exposure increased circulatory insulin, triglycerides (TG), and total cholesterol (TC), and decreased high-density lipoprotein (HDL) in both C57BL/6 and db/db mice. The levels of NLRP3-related circulatory inflammatory cytokines including both interleukin (IL)-18 and IL-1ß in serum were increased in the PM2.5-exposed mice and accompanied by the elevation in fasting blood glucose and insulin. The results also showed that exposure to PM2.5 promoted the activation of NLRP3, pro-caspase-1, caspase-1, and apoptosis-associated speck-like protein containing CARD (ASC), simultaneously accompanied by the increase of IL-18 and IL-1ß expression in VAT, but the statistically significant difference only found in the db/db mice, not in C57BL/6 mice. CONCLUSION: The activation of NLRP3 inflammasome might be not the main mechanism of PM2.5-related metabolic disorders in wide type mice but it partly mediated the exacerbation of metabolic disorders in diabetic model mice.