Fluoride Exposure Induced Bloom of Erysipelatoclostridium Ramosum Mediates the Exacerbation of Obesity in High-fat-diet Fed Mice

Background: Fluoride, a necessary mineral element for our health, is widely presented in drinking water and foods. The intake of excessive fluoride showed potential risk to human health. A strong relation between fluoride exposure and obesity has been reported. However, the knowledge on the potential mechanisms on fluoride-induced obesity is still limited.Results: In this work, we showed here that fluoride alone did not induce obesity in normal diet fed mice, whereas, it could trigger exacerbation of obesity in high-fat diet (HFD) fed mice. Fluoride impaired intestinal barrier and activated Toll-like receptor 4 (TLR4) signaling to induce obesity, which was further verified in TLR4-/- mice. Furthermore, fluoride could deteriorate the gut microbiota in HFD mice. The fecal microbiota transplantation from fluoride-induced mice was sufficient to induce obesity, while the exacerbation of obesity by fluoride was blocked upon gut microbiota depletion. The fluoride-induced bloom of Erysipelatoclostridium ramosum belonged to Erysipelotrichaceae was responsible for the exacerbation of obesity. In addition, a potential strategy for prevention of fluoride-induced obesity was proposed by intervention with polysaccharides from Fuzhuan brick tea.Conclusions: Overall, these results provide the first evidence of a comprehensive cross-talk mechanism between fluoride and obesity in HFD fed mice, which is mediated by gut microbiota and intestinal barrier. E. ramosum was identified as a crucial mediator of fluoride-induced obesity, which could be explored as potential target for prevention and treatment of obesity with exciting translational value.