Fluoride exposure induces mitochondrial damage and mitophagy via activation of the IL-17A pathway in hepatocytes

Abstract

As an environmental toxicant, the damage of fluoride to the body has attracted global attention. Because liver is an essential organ for fluoride accumulation and damage. Our previous studies revealed fluoride-induced hepatic injury through interleukin 17A (IL-17A) pathway, but the underlying cellular mechanism remains unclear. Hence, this research explored the mechanism of IL-17A pathway and mitophagy in fluoride-induced liver injury through the use of the mice fluorosis model, IL-17A addition fluorosis cell model, IL-17A gene knockout mice fluorosis model, flow cytometry, immunohistochemistry, fluorescence double staining, ELISA, western blotting, and other techniques. The results showed that fluoride reduced the bodyweight and liver coefficient, increased the bone fluoride content, the aspartate aminotransferase (AST), alanine aminotransferase (ALT), glutamate dehydrogenase (GDH) levels, caspase 8 and caspase 9 activities, and induced liver morphology and ultrastructure damage. Furthermore, the protein expression levels of IL-17A pathway key proteins, IL-17A, IL-17R, and Act1 were increased, but IκB was decreased after fluoride exposure. In addition, fluoride exposure elevated the mitochondrial depolarization percent, the mitochondria damage, the fluorescent spots of mitophagy, and the LC3II/LC3I protein relative expression level. To further verify the role of the IL-17A pathway in fluoride-induced hepatocyte mitochondrial damage and mitophagy disorder, the IL-17A was added and knocked out in cells of animals. The results showed that the addition of IL-17A aggravated fluoride-induced liver morphology and functional damage, activation of the IL-17A pathway, mitochondrial injury, and mitophagy, but the IL-17A knockout mitigated fluoride-induced changes. These results suggested that fluoride exposure induced mitochondrial damage and mitophagy through the IL-17A pathway in hepatocytes.