Thallium(I) exposure perturbs the gut microbiota and metabolic profile as well as the regional immune function of C57BL/6 J mice

Transplacental and genotoxicity effects of thallium(I) during organogenesis in mice

The increased concentration of thallium (Tl) in the environment is a cause for concern because the entire population, including pregnant women, is exposed, and this metal crosses the placenta and reaches the conceptus during development. In biological models such as mice, some abnormalities and delays in ossification occur in the fetuses of mice administered Tl on day 7 of gestation, but exposure to environmental Tl is constant during fetal development; therefore, in this study, the effects of several administrations of TI during organogenesis on the external morphology, skeletal development and genotoxicity of fetuses were evaluated. Four groups of 10 pregnant mice were administered 5.28, 6.16, 7.4 or 9.25 mg/kg body weight Tl(I) acetate intraperitoneally during fetal organogenesis. Additionally, samples were taken from fetuses from pregnant mice treated with 5.28 and 6.16 mg/kg body weight to evaluate the transplacental genotoxicity. The results revealed that the 9.25 mg/kg body weight dose produced maternal and fetal toxicity, and all of the treatment groups presented relatively high percentages of fetuses with external abnormalities, reduced bone ossification, and an increased percentage of liver cells with structural chromosomal aberrations (SCAs) and micronuclei (MNs) in blood cells. These results show that Tl(I) acetate administered during organogenesis produces abnormalities, including a delay in ossification and transplacental genotoxicity, in mouse fetuses. These findings are important because Tl has negative effects on development and may affect the health of offspring in the future because it can damage genetic material.

Testosterone regulates thymic remodeling by altering metabolic reprogramming in male rats

The thymus is an energy-consuming organ, and its metabolism changes with atrophy. Testosterone regulates thymus remodeling (atrophy and regeneration). However, the characteristics of the energy metabolism during testosterone-mediated thymic atrophy and regeneration remain unclear. In this study, we demonstrated that testosterone ablation (implemented by immunocastration and surgical castration) induced global metabolic changes in the thymus. Kyoto Encyclopedia of Genes and Genomes pathway enrichment for differential metabolites and metabolite set enrichment analysis for total metabolites revealed that testosterone ablation affected thymic glycolysis, glutamate metabolism, and fatty acid β-oxidation. Testosterone ablation-induced thymic regeneration was accompanied by attenuated glycolysis and glutamate metabolism and changed fatty acid composition and content. Testosterone supplementation in immunocastrated and surgically castrated rats enhanced glutaminolysis, reduced the level of unsaturated fatty acids, enhanced the β-oxidation of unsaturated fatty acids in the mitochondria, boosted the tricarboxylic acid (TCA) cycle, and accelerated thymic atrophy. Overall, these results imply that metabolic reprogramming is directly related to thymic remodeling.

Thallium exposure induces changes in B and T cell generation in mice

Thallium (Tl) is a high-priority toxic metal that poses a severe threat to human health. The toxicity characteristics induced by Tl have been partially discussed. However, the immunotoxic effects of Tl exposure have remained largely unexplored. Our findings demonstrated that 50 ppm of Tl exposure for one week induced severe weight loss in mice, which was accompanied by appetite suppression. Moreover, although Tl exposure did not induce significant pathological damage to skeletal muscle and bone, Tl inhibited the expression of B cell development-related genes in the bone marrow. Additionally, Tl exposure increased B cell apoptosis and reduced its generation in the bone marrow. Analysis of B cells in the blood indicated that the percentage of B-2 cells decreased significantly, whereas B-2 cell proportions in the spleen did not. The percentage of CD4⁺ T cells in the thymus increased significantly, and the proportion of CD8⁺ T cells did not. Furthermore, although the proportion of the total CD4⁺ and CD8⁺ T cells was not significantly altered in the blood and spleen, Tl exposure promoted the migration of naïve CD4⁺ T cells and recent thymic emigrants (RTEs) from the thymus to the spleen. These results suggest that Tl exposure can affect B and T cell generation and migration, which provides new evidence for Tl-induced immunotoxicity.

Thallium(III) exposure alters diversity and co-occurrence networks of bacterial and fungal communities and intestinal immune response along the digestive tract in mice

The gut microbiota, which includes fungi and bacteria, plays an important role in maintaining gut health. Our previous studies have shown that monovalent thallium [Tl(I)] exposure is associated with disturbances in intestinal flora. However, research on acute Tl(III) poisoning through drinking water and the related changes in the gut microbiota is insufficient. In this study, we showed that Tl(III) exposure (10 ppm for 2 weeks) reduced the alpha diversity of bacteria in the ileum, colon, and feces of mice, as well as the alpha diversity of fecal fungi. In addition, principal coordinate analysis showed that Tl(III) exposure had little effect on the bacterial and fungal beta diversity. LEfSe analyses revealed that Tl(III) exposure altered the abundance of intestinal bacteria in the digestive tract and feces. Moreover, Tl(III) exposure had little effect on fungal abundance in the ileum, cecum, and colon, but had a considerable effect on fungal abundance in feces. After Tl(III) exposure, the fungal composition was more disrupted in feces than in the intestinal tract, suggesting that feces can serve as a representative of the gut mycobiota in Tl(III) exposure studies. Intra-kingdom network analyses showed that Tl(III) exposure affected the complexity of bacterial-bacterial and fungal-fungal co-occurrence networks along the digestive tract. The bacterial-fungal interkingdom co-occurrence networks exhibited increased complexity after Tl(III) exposure, except for those in the colon. Additionally, Tl(III) exposure altered the intestinal immune response. These results reveal the perturbation in gut bacterial and fungal diversity, abundance, and co-occurrence network complexity, as well as the gut immune response, caused by Tl(III) exposure.