Fluoride exposure cause colon microbiota dysbiosis by destroyed microenvironment and disturbed antimicrobial peptides expression in colon

Colon microenvironment and microbiota dysbiosis are closely related to various human metabolic diseases. In this study, a total of 72 healthy female mice were exposed to fluoride (F) (0, 25, 50 and 100 mg/L F⁻) in drinking water for 70 days. The effect of F on intestinal barrier and the diversity and composition in colon microbiota have been evaluated. Meanwhile, the relationship among F-induced colon microbiota alterations and antimicrobial peptides (AMPs) expression and short-chain fatty acids (SCFAs) level also been assessed. The results suggested that F decreased the goblet cells number and glycoprotein expression in colon. And further high-throughput 16S rRNA gene sequencing result demonstrated that F exposure induced the diversity and community composition of colonic microbiota significantly changes. Linear Discriminant Analysis Effect Size (LEfSe) analysis identified 11 predominantly characteristic taxa which may be the biomarker in response to F exposure. F-induced intestinal microbiota perturbations lead to the significantly decreased SCFAs levels in colon. Immunofluorescence results showed that F increased the protein expression of interleukin-17A (IL-17A) and IL-22 (P < 0.01) and disturbed the expression of interleukin-17 receptor A (IL-17RA) and IL-22R (P < 0.05 or P < 0.01). In addition, the increased expression of IL-17A and IL-22 cooperatively enhanced the mRNA expression of AMPs which response to F-induced microbiota perturbations. Collectively, destroyed microenvironment and disturbed AMPs are the primary reason of microbiota dysbiosis in colon after F exposure. Colonic homoeostasis imbalance would be helpful for finding the source of F-induced chronic systemic diseases.