Fluoride induces immunotoxicity by regulating riboflavin transport and metabolism partly through IL-17A in the spleen.

The impairment of the immune system by fluoride is a public health concern worldwide, yet the underlying mechanism is unclear. Both riboflavin and IL-17A are closely related to immune function and regulate the testicular toxicity of fluoride. However, whether riboflavin or IL-17A is involved in fluoride-induced immunotoxicity is unknown. Here, we first established a male ICR mouse model by treating mice with sodium fluoride (NaF) (100 mg/L) via the drinking water for 91 days. The results showed that fluoride increased the expression of the proinflammatory factors IL-1ß and IL-17A, which led to splenic inflammation and morphological injury. Moreover, the expression levels of the riboflavin transporters SLC52A2 and SLC52A3; the transformation-related enzymes RFK and FLAD1; and the key mitochondrial functional determinants SDH, COX, and ATP in the spleen were measured via real-time PCR, Western blotting, and ELISA. The results revealed that fluoride disrupted riboflavin transport, transformation, metabolism, and mitochondrial function. Furthermore, wild-type (WT) and IL-17A knockout (IL-17A-/-) C57BL/6 J male mice of the same age were treated with NaF (24 mg/kg·bw, equivalent to 100 mg/L) and/or riboflavin sodium phosphate (5 mg/kg·bw) via gavage for 91 days. Similar parameters were evaluated as above. The results confirmed that fluoride increased riboflavin metabolism through RFK but not through FLAD1. Fluoride also affected mitochondrial function and activated neutrophils (marked with Ly6g) and macrophages (marked with CD68) in the spleen. Interestingly, IL-17A partly mediated fluoride-induced riboflavin metabolism disorder and immunotoxicity in the spleen. This work not only reveals a novel toxic mechanism for fluoride but also provides new clues for exploring the physiological function of riboflavin and for diagnosing and treating the toxic effects of fluoride in the environment.

Bifidobacterium Relieved Fluoride-Induced Hepatic and Ileal Toxicity via Inflammatory Response and Bile Acid Transporters in Mice.

Fluoride is a pervasive environmental contaminant. Prolonged excessive fluoride intake can inflict severe damage on the liver and intestines. Previous 16S rDNA sequencing revealed a decrease in ileal Bifidobacterium abundance during fluoride-induced hepatointestinal injury. Hence, this work aimed to investigate the possible mitigating function of Bifidobacterium on hepatointestinal injury caused by fluoride. Thirty-six 6-week-old C57BL/6J mice (equally divided between males and females) were allotted randomly to three groups: Ctrl group (distilled water), NaF group, and NaF + Ba group (100 mg/L NaF distilled water). After 10 weeks, the mice were given 1 × 109 CFU/mL Bifidobacterium solution (0.2 mL/day) intragastrically in the NaF + Ba group for 8 weeks, and the mice in other groups were given the same amount of distilled water. Dental damage, bone fluoride content, blood routine, liver and intestinal microstructure and function, inflammatory factors, and regulatory cholic acid transporters were examined. Our results showed that fluoride increased glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT) activities, and the levels of lipopolysaccharide (LPS), IL-1ß, IL-6, TNF-α, and IL-10 levels in serum, liver, and ileum. However, Bifidobacterium intervention alleviated fluoride-induced changes in the above indicators. In addition, Bifidobacterium reduced the mRNA expression levels of bile acid transporters ASBT, IBABP, OST-α, and OST-ß in the ileum. In summary, Bifidobacterium supplementation relieved fluoride-induced hepatic and ileal toxicity via an inflammatory response and bile acid transporters in the liver and ileum of mice.

KIF2A participates in the progression of hepatocellular carcinoma and angiogenesis by interacting with Notch1.

Kinesin family member 2A (KIF2A) serves a vital role in the development of hepatocellular carcinoma (HCC); however, the biological effect of KIF2A on the malignant progression of HCC remains unclear. Therefore, the present study was conducted to systematically determine the biological role of KIF2A in HCC and to better understand the molecular mechanism. The differences of KIF2A expression in HHL-5 normal human hepatocytes and the HCC cell lines Li-7, Huh7 and MHCC97 were assessed by reverse transcription-quantitative PCR and western blotting analysis. Moreover, viability, proliferation, migration and invasion of HCC cells were assessed by performing CCK-8, 5-ethynyl-2'-deoxyuridine staining, wound healing and Transwell assays. Additionally, the tube formation assay was performed to evaluate angiogenesis of HUVECs incubated with the conditioned media of HCC cells in vitro. The interaction between KIF2A and Notch1 was analyzed through co-immunoprecipitation assay. KIF2A was revealed to be highly expressed in HCC cells. KIF2A knockdown suppressed HCC cell proliferation, migration and invasion, and impaired in vitro angiogenesis. Furthermore, it was revealed that KIF2A interacted with Notch1 and positively regulated Notch1 expression. The suppressive effects of KIF2A knockdown on HCC cell proliferation, migration, invasion and in vitro angiogenesis were partially reversed by Notch1 overexpression. Overall, KIF2A may act as an oncogene in HCC via activation of the Notch1 signaling pathway.