Chondrocyte autophagy mediated by T-2 toxin via AKT/TSC/Rheb/mTOR signaling pathway and protective effect of CSA-SeNP.

OBJECTIVE: Kashin-Beck disease (KBD) is an endemic, degenerative, and cartilage-damaging disease for which low selenium and T-2 toxins are considered environmental pathogenic factors. This study aimed to investigate the molecular mechanisms of autophagy in cartilage damage caused by T-2 toxin and the protective effect of chondroitin sulfate A nano-elemental selenium (CSA-SeNP) on the cartilage. METHODS: KBD chondrocytes and C28/I2 human chondrocyte cell lines were used. T-2 toxin, AKT inhibitor, and CSA-SeNP treatment experiments were conducted separately, with a treatment time of 24 h. Autophagy was monitored using MDC staining, and mRFP-GFP-LC3 adenovirus, respectively. RT-qPCR and western blotting were used to detect the expression of the relevant genes and proteins. RESULTS: The suppression of autophagy observed in KBD chondrocytes was replicated by applying 10 ng/mL T-2 toxin to C28/I2 chondrocytes for 24 h. The AKT/TSCR/Rheb/mTOR signaling pathway was activated by T-2 toxin, which inhibits autophagy. The supplementation with CSA-SeNP alleviated the inhibition of autophagy by T-2 toxin through the AKT/TSCR/Rheb/mTOR signaling pathway. CONCLUSIONS: Loss of autophagy regulated by the AKT/TSCR/Rheb/mTOR signaling pathway plays an important role in cartilage damage caused by T-2 toxin. CSA-SeNP supplementation attenuated inhibition of autophagy in chondrocytes by T-2 toxin by modulating this signaling pathway. These findings provide promising new targets for the prevention and treatment of cartilage disease.

An untargeted metabolomics study of cardiac pathology damage in rats caused by low selenium diet alone or in combination with T-2 toxin.

T-2 toxin is a highly cardiotoxic environmental contaminant. Selenium can uphold the cardiovascular system's functionality. Selenium insufficiency is common. The aim of this study was to elucidate the effects of low selenium diet alone or in combination with T-2 toxin on myocardial tissue damage. Thirty-two Sprague-Dawley rats of 3 weeks of age were randomized into control, low selenium diet, low selenium diet combined with T-2 toxin groups (at doses of 10 ng/g and 100 ng/g body weight) for 12-weeks intervention. Pathohistology and ultrastructural changes in cardiac tissue were observed. Changes in cardiac metabolites were analyzed using untargeted metabolomics. The findings demonstrated that cardiac tissue abnormalities, interstitial bleeding, inflammatory cell infiltration, and mitochondrial damage can be brought on by low selenium diet alone or in combination with the T-2 toxin. A low selenium diet alone or in combination with the T-2 toxin affected cardiac metabolic profiles and resulted in aberrant modifications in many metabolic pathways, including the metabolism of amino acids, cholesterol, and thiamine. Accordingly, low selenium diet and T-2 toxin may have a synergistic effect. Our findings provide fresh insights into the processes of cardiac injury by revealing the effects of low selenium diet and T-2 toxin on cardiac metabolism.

Low selenium and T-2 toxin may be involved in the pathogenesis of Kashin-Beck disease by affecting AMPK/mTOR/ULK1 pathway mediated autophagy.

Kashin-Beck disease (KBD) is an endemic, environmentally associated cartilage disease. Previous studies have shown that the environmental suspected pathogenic factors of KBD, T-2 toxin and low selenium, are involved in the regulation of inflammation, oxidative stress and autophagy in some tissues and organs. In cartilage diseases, the level of cellular autophagy determines the fate of the chondrocytes. However, whether autophagy is involved in KBD cartilage lesions, and the role of low selenium and T-2 toxins in KBD cartilage injury and autophagy are still unclear. This work took the classical AMPK/mTOR/ULK1 autophagy regulatory pathway as the entry point to clarify the relationship between the environmental suspected pathogenic factors and chondrocyte autophagy. Transmission electron microscopy was used to observe the autophagy of chondrocytes in KBD patients. qRT-PCR and western blot were used to analyze the expression of AMPK/mTOR/ULK1 pathway and autophagy markers. The rat model of KBD was established by low selenium and T-2 toxin, the autophagy in rat cartilage was detected after 4- and 12-week interventions. Chondrocyte autophagy was found in KBD, and the AMPK/mTOR/ULK1 pathway was down-regulated. In the rat model, the pathway showed an up-regulated trend when low selenium and T-2 toxin, were treated for a short time or low concentration, and autophagy level increased. However, when low selenium and T-2 toxin were treated for a long time or at high concentrations, the pathway showed a down-regulated trend, and the autophagy level was reduced and even defective. In conclusion, in the process of KBD cartilage lesion, chondrocyte autophagy level may increase in the early stage, and decrease in the late stage with the progression of lesion. Low selenium and T-2 toxins may affect autophagy by AMPK/mTOR/ULK1 pathway.

The Association between Serum Copper and Bone Mineral Density among Adolescents Aged 12 to 19 in the United States.

Bone mineral density (BMD) is a key parameter widely used in the assessment of bone health. Although many investigations have explored the relationship between trace elements and BMD, there are fewer studies focused on serum copper and BMD, especially for adolescents. Using data extracted from the National Health and Nutrition Examination Survey, we applied a multiple-linear regression and smooth curve fitting to assess the relationship between serum copper and BMD. A total of 910 participants were finally included in this study. After adjusting for relevant covariates, serum copper was negatively associated with lumbar spine BMD (ß = -0.057, 95% CI: -0.109 to -0.005), trunk bone BMD (ß = -0.068, 95% CI: -0.110 to -0.026), pelvis BMD (ß = -0.085, 95% CI: -0.145 to -0.024), subtotal BMD (ß = -0.072, 95% CI: -0.111 to -0.033), and total BMD (ß = -0.051, 95% CI: -0.087 to -0.016) (p < 0.05). In quartile analysis, the highest level of serum copper was associated with decreased BMD when compared with those at the lowest quartile (p < 0.05). The stratified analysis revealed a significant interaction between age and the effects of serum copper on trunk bone BMD (p = 0.022) and pelvis BMD (p = 0.018). Meanwhile, the higher level of serum copper was negatively associated with BMD in males, and gender modified the relationship (p < 0.001). Future longitudinal studies will be necessary for a more definitive interpretation of our results.

Association of blood cadmium levels and all-cause mortality among adults with rheumatoid arthritis: The NHANES cohort study.

BACKGROUND: The potential impact of environmental cadmium exposure on the prognosis of patients with rheumatoid arthritis (RA) remains unclear, despite its known association with various adverse health outcomes. METHODS: In this study, a total of 1285 RA patients were included in the National Health and Nutrition Examination Survey (NHANES) conducted between 2003 and 2016. The Cox regression model was employed to investigate the relationship between blood cadmium levels and the risk of all-cause mortality in RA patients. RESULTS: During a mean follow-up duration of 105.9 months, 341 patient deaths were recorded. After adjusting for multiple factors, elevated blood cadmium was strongly correlated with an increased risk of all-cause mortality in patients with RA. With one unit rise in natural logarithm-transformed blood cadmium concentrations, the risk of patient death increased by 107%. The adjusted hazard ratios for each quartile of blood cadmium demonstrated a significant upward trend (P < 0.001). A linear dose-response relationship of blood cadmium concentrations with all-cause mortality was also distinctive (P < 0.001). Consistent findings were ascertained when conducting stratified analyses by age, gender, race, education level, body mass index, smoking status, and drinking status. CONCLUSIONS: Elevated blood cadmium levels may serve as a risk factor for increased death risk in RA patients.

Synergistic effects of T-2 toxin and selenium deficiency exacerbate renal fibrosis through modulation of the ERα/PI3K/Akt signaling pathway.

As common pathogenic agents in the world and widely distributed globally, T-2 toxin and selenium deficiency might exacerbate toxic effects by combined exposure, posing a dramatic health hazard to humans and animals. In this study, we aim to elucidate the underlying mechanisms of renal fibrosis triggered by T-2 toxin and selenium deficiency exposure. A total of thirty-two rats are randomly divided into the normal control, T-2 toxin, selenium deficiency, and combined intervention groups. T-2 toxin (100 ng/g) is intragastric gavaged to the rats in compliance with the body weight. Both the standard (containing selenium 0.20 mg/Kg) and selenium-deficient (containing selenium 0.02 mg/Kg) diets were manufactured adhering to the AIN-93 formula. After 12 weeks of intervention, renal tissue ultrastructural and pathological changes, inflammatory infiltration, epithelial mesenchymal transition (EMT), and extracellular matrix (ECM) deposition are evaluated, respectively. Metabolomics analysis is conducted to explore the underlying pathology of renal fibrosis, followed by the validation of potential mechanisms at gene and protein levels. T-2 toxin and selenium deficiency exposure results in podocyte foot process elongation or fusion, tubular vacuolization and dilatation, and collagen deposition in the kidneys. Additionally, it also increases inflammatory infiltration, EMT conversion, and ECM deposition. Metabolomics analysis suggests that T-2 toxin and selenium deficiency influence amino acid and cholesterol metabolism, respectively, and the estrogen signaling pathway is probably engaged in renal fibrosis progression. Moreover, T-2 toxin and selenium deficiency are found to regulate the expressions of the ERα/PI3K/Akt signaling pathway. In conclusion, T-2 toxin and selenium deficiency synergistically exacerbate renal fibrosis through regulating the ERα/PI3K/Akt signaling pathway, and inflammatory infiltration, EMT and ECM deposition are involved in this process.

Mediator subunit MED1 deficiency prevents carbon tetrachloride-induced hepatic fibrosis in mice.

Mediator subunit mediator 1 (MED1) mediates ligand-dependent binding of the mediator coactivator complex to various nuclear receptors and plays a critical role in embryonic development, lipid and glucose metabolism, liver regeneration, and tumorigenesis. However, the precise role of MED1 in the development of liver fibrosis has been unclear. Here, we showed that MED1 expression was increased in livers from nonalcoholic steatohepatitis (NASH) patients and mice and positively correlated with transforming growth factor ß (TGF-ß) signaling and profibrotic factors. Upon treatment with carbon tetrachloride (CCl4), hepatic fibrosis was much less in liver-specific MED1 deletion (MED1ΔLiv) mice than in MED1fl/fl littermates. TGF-ß/Smad2/3 signaling pathway was inhibited, and gene expression of fibrotic markers, including α-smooth muscle actin (α-SMA), collagen type 1 α 1 (Col1a1), matrix metalloproteinase-2 (Mmp2), and metallopeptidase inhibitor 1 (Timp1) were decreased in livers of MED1ΔLiv mice with CCl4 injection. Transcriptomic analysis revealed that the differentially expressed genes in livers of CCl4-administered MED1ΔLiv mice were enriched in the pathway of oxidoreductase activity, followed by robustly reduced oxidoreductase activity-related genes, such as Gm4756, Txnrd3, and Etfbkmt. More importantly, we found that the reduction of reactive oxygen species (ROS) in MED1 knockdown hepatocytes blocked the activation of TGF-ß/Smad2/3 pathway and the expression of fibrotic genes in LX2 cells. These results indicate that MED1 is a positive regulator for hepatic fibrogenesis, and MED1 may be considered as a potential therapeutic target for the regression of liver fibrosis.NEW & NOTEWORTHY In this study, we present the first evidence that liver mediator 1 (MED1) deficiency attenuated carbon tetrachloride-induced hepatic fibrosis in mouse. The underlying mechanism is that MED1 deficiency reduces reactive oxygen species (ROS) production in hepatocytes, thus restricts the activation of TGF-ß/Smad2/3 signaling pathway and fibrogenic genes expression in hepatic stellate cells (HSCs). These data suggest that MED1 is an essential regulator for hepatic fibrogenesis, and MED1 may be considered as a potential therapeutic target for liver fibrosis.

Hepatic transcriptome signatures in mice and humans with nonalcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the main reason for cirrhosis and hepatocellular carcinoma. As a starting point for NAFLD, the treatment of nonalcoholic fatty liver (NAFL) is receiving increasing attention. Mice fed a high-fat diet (HFD) and hereditary leptin deficiency (ob/ob) mice are important NAFL animal models. However, the comparison of these mouse models with human NAFL is still unclear. METHODS: In this study, HFD-fed mice and ob/ob mice were used as NAFL animal models. Liver histopathological characteristics were compared, and liver transcriptome from both mouse models was performed using RNA sequencing (RNA-seq). RNA-seq data obtained from the livers of NAFL patients was downloaded from the GEO database. Global gene expression profiles in the livers were further analyzed using functional enrichment analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. RESULTS: Our results showed that the biochemical parameters of both mouse models and human NAFL were similar. Compared with HFD-fed mice, ob/ob mice were more similar in histologic appearance to NAFL patients. The liver transcriptome characteristics partly overlapped in mice and humans. Furthermore, in the NAFL pathway, most genes showed similar trends in mice and humans, thus demonstrating that both types of mice can be used as models for basic research on NAFL, considering the differences. CONCLUSION: Our findings show that HFD-fed mice and ob/ob mice can mimic human NAFL partly in pathophysiological process. The comparative analysis of liver transcriptome profile in mouse models and human NAFL presented here provides insights into the molecular characteristics across these NAFL models.

Progress of Selenium Deficiency in the Pathogenesis of Arthropathies and Selenium Supplement for Their Treatment.

Selenium, an essential trace element for human health, exerts an indispensable effect in maintaining physiological homeostasis and functions in the body. Selenium deficiency is associated with arthropathies, such as Kashin-Beck disease, rheumatoid arthritis, osteoarthritis, and osteoporosis. Selenium deficiency mainly affects the normal physiological state of bone and cartilage through oxidative stress reaction and immune reaction. This review aims to explore the role of selenium deficiency and its mechanisms existed in the pathogenesis of arthropathies. Meanwhile, this review also summarized various experiments to highlight the crucial functions of selenium in maintaining the homeostasis of bone and cartilage.