Co-exposure to lead and high-fat diet aggravates systemic inflammation in mice by altering gut microbiota and the LPS/TLR4 pathway.

This study reports the toxicity of Pb exposure on systemic inflammation in high-fat-diet (HFD) mice and the potential mechanisms. Results indicated that Pb exacerbated intestinal barrier damage and increased serum levels of lipopolysaccharide (LPS) and diamine oxidase in HFD mice. Elevated LPS activates the colonic and ileal LPS-TLR4 inflammatory signaling pathway and further induces hepatic and adipose inflammatory expression. The 16S rRNA gene sequencing results showed that Pb promoted the abundance of potentially harmful and LPS-producing bacteria such as Coriobacteriaceae_UCG-002, Alloprevotella, and Oscillibacter in the intestines of HFD mice, and their abundance was positively correlated with LPS levels. Additionally, Pb inhibited the abundance of the beneficial bacteria Akkermansia, resulting in lower levels of the metabolite short-chain fatty acids (SCFAs). Meanwhile, Pb inhibited adenosine 5'-monophosphate-activated protein kinase signaling-mediated lipid metabolism pathways, promoting hepatic lipid accumulation. The above results suggest that Pb exacerbates systemic inflammation and lipid disorders in HFD mice by altering the gut microbiota, intestinal barrier, and the mediation of metabolites LPS and SCFAs. Our study provides potential novel mechanisms of human health related to Pb-induced metabolic damage and offers new evidence for a comprehensive assessment of Pb risk.

Lead exposure exacerbates liver injury in high-fat diet-fed mice by disrupting the gut microbiota and related metabolites.

Lead (Pb) is a widespread toxic endocrine disruptor that could cause liver damage and gut microbiota dysbiosis. However, the causal relationship and underlying mechanisms between the gut microbiota and Pb-induced liver injury are unclear. In this study, we investigated the metabolic toxicity caused by Pb exposure in normal chow (Chow) and high-fat diet (HFD) mice and confirmed the causal relationship by fecal microbial transplantation (FMT) and antibiotic cocktail experiments. The results showed that Pb exposure exacerbated HFD-induced hepatic lipid deposition, fibrosis, and inflammation, but it had no significant effect on Chow mice. Pb increased serum lipopolysaccharide (LPS) levels and induced intestinal inflammation and barrier damage by activating TLR4/NFκB/MLCK in HFD mice. Furthermore, Pb exposure disrupted the gut microbiota, reduced short-chain fatty acid (SCFA) concentrations and the colonic SCFA receptors, G protein-coupled receptor (GPR) 41/43/109A, in HFD mice. Additionally, Pb significantly inhibited the hepatic GPR109A-mediated adenosine 5'-monophosphate-activated protein kinase (AMPK) pathway, resulting in hepatic lipid accumulation. FMT from Pb-exposed HFD mice exacerbated liver damage, disturbed lipid metabolic pathways, impaired intestinal barriers, and altered the gut microbiota and metabolites in recipient mice. However, mice exposed to HFD + Pb and HFD mice had similar levels of these biomarkers in microbiota depleted by antibiotics. In conclusion, our study provides new insights into gut microbiota dysbiosis as a potential novel mechanism for human health related to liver function impairment caused by Pb exposure.

Lead exposure aggravates glucose metabolism disorders through gut microbiota dysbiosis and intestinal barrier damage in high-fat diet-fed mice.

BACKGROUND: Lead (Pb) is an ancient toxic metal and is still a major public health issue. Our previous study found that Pb exposure promotes metabolic disorders in obese mice, but the molecular mechanisms remain unclear. The present study explored the effects of Pb exposure on glucose homeostasis in mice fed a normal diet (ND) and high-fat diet (HFD) from the perspective of gut microbiota. RESULTS: Pb exposure had little effect on glucose metabolism in ND mice, but exacerbated hyperglycemia and insulin resistance, and impaired glucose tolerance in HFD mice. Pb exposure impaired intestinal tight junctions and mucin expression in HFD mice, increasing intestinal permeability and inflammation. Moreover, Pb exposure altered the composition and structure of the gut microbiota and decreased short-chain fatty acids (SCFAs) levels in HFD mice. Correlation analysis revealed that the gut microbiota and SCFAs were significantly correlated with the gut barrier and glucose homeostasis. Furthermore, the fecal microbiota transplantation from Pb-exposed HFD mice resulted in glucose homeostasis imbalance, intestinal mucosal structural damage and inflammation in recipient mice. However, Pb did not exacerbate the metabolic toxicity in HFD mice under depleted gut microbiota. CONCLUSION: The findings of the present study suggest that Pb induces impairment of glucose metabolism in HFD mice by perturbing the gut microbiota. Our study offers new perspectives on the mechanisms of metabolic toxicity of heavy metals and demonstrates that the gut microbiota may be a target of action for heavy metal exposure. © 2023 Society of Chemical Industry.