Effects of prolonged fluoride exposure on innate immunity, intestinal mechanical, and immune barriers in mice.

The aim of this study is to explore the effects of fluoride on the innate immunity, intestinal mechanical barrier, and immune barrier of C57BL/6 mice, as well as to analyze the degree of structural and tissue damage, providing reference data for related research. Mice were randomly divided into four groups and then treated with 0 mg/L (control), 50 mg/L, 100 mg/L, 125 mg/L sodium fluoride solution, respectively, for 120 days. Histological technique, ELISA, MTT colorimetry methods were used to detect and analyze the effects of different concentrations of fluoride on the intestinal morphology, mechanical barrier and the immune functions and innate immunity of mice. The results showed that compared with the control group, the villi were injured in different degrees of the three fluoride groups, the number of goblet cells, the protein expression levels of connexin ZO-1, Claudin-1 and Occludin, the content of Diamine Oxidase (DAO), endotoxin (ET) and D-lactic acid (D-LA), the activity of natural killer cell (NK cells), the number and percentage of neutrophils and erythrocytes, the phagocytic rate of neutrophils, and the rate of C3bR rosette (which is formed by the adhesion of C3b receptors on the red blood cell membrane to complement sensitized yeast) and IC rosette (which is formed by the adhesion of C3b molecules in the immunecomplex adhered to the red blood cell membrane to non sensitized yeast) of red blood cells, the content of interlenkin 1 beta (IL-1β) and interlenkin 8 (IL-8), the number and percentage of lymphocytes decreased with the increasing of fluoride concentration. In addition, the content of the Immunoglobulin A (sIgA) showed a trend of increase at first and then decrease in salivary gland and jejunum. It is concluded that excessive intake of fluoride for a long time has a certain damage effect on the intestinal tract, leading to an increase in the permeability of the intestinal tract, thereby destroying the mechanical and immune barrier function of the intestinal tract.