Nano-selenium Alleviates Cadmium-Induced Mouse Leydig Cell Injury, via the Inhibition of Reactive Oxygen Species and the Restoration of Autophagic Flux

Unveiling the nexus between environmental exposures and testicular damages: revelations from autophagy and oxidative stress imbalance

Recent evidence consolidates the deleterious impact of environmental exposure on testicular damage. Environmental exposures can instigate testicular toxicity, causing damage to the Sertoli-Sertoli cell-mediated blood-testis barrier (BTB) integrity, alterations in hormone levels orchestrated by aberrant Leydig cells, and disruption of spermatogenesis. Despite diverse study designs and methodologies, a consensus is emerging on how environmental factors induce oxidative stress by elevating ROS levels, affecting autophagy through pathways such as the ROS-mediated mTOR signaling pathway, ultimately culminating in testicular damage. This review synthesizes existing literature on how environmental exposures, including metals, air pollutants, industrial contaminants, and pesticides, disturb testicular homeostasis via autophagy-mediated oxidative stress, highlighting recent significant advancements. It also explores interventions like antioxidant support and autophagy regulation to alleviate testicular damage. These findings underscore the importance of elucidating the mechanisms of autophagy influenced by environmental exposures in disrupting the equilibrium of oxidative stress, identifying potential drug targets, and establishing a groundwork for enhancing future treatments and clinical management of testicular injuries.

Cadmium exposure induces Leydig cell injury via necroptosis caused by oxidative stress and TNF-α/TNFR1 signaling

Cadmium, a ubiquitous environmental pollutant, has been linked to testicular damage, primarily through mechanisms such as oxidative stress and various forms of programmed cell death. Despite extensive studies on its toxic effects, the specific role of necroptosis in cadmium-induced reproductive toxicity remains unclear. In this study, we provide critical insights into how cadmium triggers necroptosis in Leydig cells, leading to testicular dysfunction. Using both in vitro and in vivo models, we demonstrated that cadmium exposure induces necroptotic cell death in Leydig cells, with significant involvement of the TNF-α/TNFR1 signaling pathway and reactive oxygen species (ROS) generation. Co-treatment with Nec-1, a specific necroptosis inhibitor, significantly reduced elevated ROS levels and suppressed TNF-α/TNFR1-induced necroptotic cell death, suggesting that ROS and the TNF-α/TNFR1 signaling pathway contribute to necroptosis activation in cadmium-induced Leydig cell injury. In conclusion, we demonstrate that necroptosis is a key driver of cadmium-induced testicular damage, suggesting that targeting necroptosis could offer novel therapeutic strategies for mitigating reproductive toxicity caused by heavy metals.

Disentangling the role of selenium in antagonizing the toxicity of arsenic and cadmium

Cadmium (Cd) and inorganic arsenic (As) compounds are considered to be among the major public health hazards. This is due to both the high intrinsic toxicity of these substances and the often difficult to avoid exposure of the general population through contaminated water and food. One proposed method to reduce the toxic effects of As and Cd on animals and humans is the use of selenium (Se). As discussed in our previous article, laboratory studies show that this micronutrient can have a beneficial effect on the detoxification of As and Cd in the body through the formation of non-toxic complexes with these elements, as well as through the antioxidant effects of selenoproteins. New data that have emerged in recent years allow for a clearer description of the interaction between Se and As and Se and Cd. Human studies show that optimal levels of Se can have a beneficial effect in reducing the toxic effects associated with exposure to As or Cd. However, as Se levels in the body increase, the protective effects of Se may be reversed. Recent laboratory studies confirm the antagonistic effects of medium doses of Se toward Cd and As through the formation of nontoxic complexes, antioxidant, anti-inflammatory effects, and induction of pro-survival pathways in cells. In conclusion, Se has a complex effect on As and Cd toxicity, with both benefits and potential risks, depending on the form of Se and its dose as a supplement or the status (level) of this micronutrient in the body.

Getah virus triggers ROS-mediated autophagy in mouse Leydig cells

Introduction

Getah virus (GETV) is a zoonotic virus transmitted via a mosquito-vertebrate cycle. While previous studies have explored the epidemiology and pathogenicity of GETV in various species, its molecular mechanisms remain largely unexplored.

Methods

This study investigated the impact of GETV infection and associated molecular mechanisms on reactive oxygen species (ROS) and autophagy levels in mouse Leydig cells both in vivo and in vitro. The male mice and TM3 cells were treatment with N-acetylcysteine (NAC) to reduce cellular ROS levels. Rapamycin (Rapa) and 3-Methyladenine (3- MA) were used to change autophagy in both infected and uninfected TM3 cells.

Results and Discussion

The findings revealed that GETV infection in mouse testes speciffcally targeted Leydig cells and induced oxidative stress while enhancing autophagy in testicular tissue. Using TM3 cells as an in vitro model, the study confirmed GETV replication in this cell line, triggering increased ROS and autophagy levels. Treatment with N-acetylcysteine (NAC) to reduce cellular ROS levels markedly reduced autophagy in testicular tissue and TM3 cells infected with GETV. Interestingly, the use of rapamycin (Rapa) and 3-Methyladenine (3- MA) led to autophagy change in both infected and uninfected TM3 cells, with no signiffcant alterations in cellular ROS levels. These results indicate that GETV infection elevates ROS levels, subsequently inducing autophagy in mouse Leydig cells. We also found that autophagy plays an important role in GETV replication. When autophagy levels were reduced using NAC and 3-MA, a corresponding decrease in TCID50 was observed. Conversely, upregulation of autophagy using Rapa resulted in an increase in TCID50 of GETV. Therefore, we speculate that GETV may exploit the autophagy pathway to facilitate its replication. These ffndings illuminate the interplay between GETV and host cells, providing valuable insights for therapeutic strategies targeting autophagy in GETV infections.

Selenium-Enriched Aspergillus oryzae A02 Enhances Testicular Antioxidant Capacity in Mice by Regulating Intestinal Microbiota and Serum Metabolite

Selenium (Se) is a trace element that is essential for health. Organic Se created by Se-enriched microorganisms has the characteristics of low toxicity, high bioavailability, and regulation of physiological functions. Here, the regulatory effect of Se-enriched Aspergillus oryzae A02 on the reproductive function of male mice and its potential molecular mechanism was studied. Specifically, twenty-four male mice were randomly divided into a control group and a Se-enriched A. oryzae A02 (Nano-Se) (daily gavage of 0.5 mg/kg, dissolved in saline) for an 8-week experiment. The results showed that Nano-Se intervention did not affect body weight and testicular index, but increased sperm concentration and seminiferous epithelium height in experimental mice, indicating that Nano-Se has the potential to improve the reproductive performance of male mice. Mechanistically, Nano-Se intervention increased the levels of antioxidant-related indicators catalase (CAT) and glutathione peroxidase (GSH-Px) in mouse serum, and increased the relative mRNA expression of GSH-Px, heme oxygenase-1 (HO-1), and NADPH quinine oxidoreductase-1 (NQO-1) in testicular tissues. We identified 9,10,13-trihydroxyoctadecenoic acids (TriHOMEs), stearidonic acid and selenomethionine linked with alpha-linolenic acid metabolism, selenocompound metabolism, folate biosynthesis, ubiquinone, and other terpenoid-quinone biosynthesis and biosynthesis of cofactors. In addition, Nano-Se did not influence the fecal bacterial alpha and beta diversity (P > 0.05), but increased the abundance of the Actinobacteriota and Proteobacteria phyla and the Staphylococcus and Corynebacterium genera, and lowered the abundance of the Bacteroidota phylum and the Lactobacillus and norank_f_Muribaculaceae genera. Nano-Se is considered a novel and promising nutritional regulator to improve reproductive function.

Selenium restored mitophagic flux to alleviate cadmium-induced hepatotoxicity by inhibiting excessive GPER1-mediated mitophagy activation

Cadmium (Cd) is a common environmental pollutant, while selenium (Se) can ameliorate heavy metal toxicity. Consequently, this study aimed to investigate the protective effects of Se against Cd-induced hepatocyte injury and its underlying mechanisms. To achieve this, we utilized the Dongdagou-Xinglong cohort, BRL3A cell models, and a rat model exposed to Cd and/or Se. The results showed that Se counteracted liver function injury and the decrease in GPER1 levels caused by environmental Cd exposure, and various methods confirmed that Se could protect against Cd-induced hepatotoxicity both in vivo and in vitro. Mechanistically, Cd caused excessive mitophagy activation, evidenced by the colocalization of LC3B, PINK1, Parkin, P62, and TOMM20. Transfection of BRL3A cells with mt-keima adenovirus indicated that Cd inhibited autophagosome-lysosome fusion, thereby impeding mitophagic flux. Importantly, G1, a specific agonist of GPER1, mitigated Cd-induced mitophagy overactivation and hepatocyte toxicity, whereas G15 exacerbates these effects. Notably, Se supplementation attenuated Cd-induced GPER1 protein reduction and excessive mitophagy activation while facilitating autophagosome-lysosome fusion, thereby restoring mitophagic flux. In conclusion, this study proposed a novel mechanism whereby Se alleviated GPER1-mediated mitophagy and promoted autophagosome-lysosome fusion, thus restoring Cd-induced mitophagic flux damage, and preventing hepatocyte injury.

Selenomethionine Inhibits NF-κB-mediated Inflammatory Responses of Bovine Mammary Epithelial Cells Caused by Klebsiella pneumoniae by Increasing Autophagic Flux

Klebsiella pneumoniae (K. pneumoniae) is one of the major pathogens causing bovine clinical mastitis. Autophagy maintains cellular homeostasis and resists excessive inflammation in eukaryotic organisms. Selenomethionine (Se-Met) is commonly used as a source of selenium supplementation for dairy cows. This study aimed to investigate the effects of Se-Met on inflammatory responses mediated by nuclear factor-kappa B (NF-κB) through autophagy. We infected bovine mammary epithelial cell line (MAC-T) with K. pneumoniae and examined the expression of autophagy-related proteins and changes in autophagic vesicles, LC3 puncta, and autophagic flux at various intervals. The results showed that K. pneumoniae activated the early-stage autophagy of MAC-T cells. The levels of LC3-II, Beclin1, and ATG5, as well as the number of LC3 puncta and autophagic vesicles, increased after 2 h post-treatment. However, the late-stage autophagic flux was blocked. Furthermore, the effect of autophagy on NF-κB-mediated inflammation was investigated with different autophagy levels. The findings showed that enhanced autophagy inhibited the K. pneumoniae-induced inflammatory responses of MAC-T cells. The opposite results were found with the inhibition of autophagy. Finally, we examined the effect of Se-Met on NF-κB-mediated inflammation based on autophagy. The results indicated that Se-Met alleviated K. pneumoniae-induced autophagic flux blockage, inhibited NF-κB-mediated inflammation, and decreased the adhesion of K. pneumoniae to MAC-T cells. The inhibitory effect of Se-Met on NF-κB-mediated inflammation could be partially blocked by the autophagy inhibitor chloroquine (CQ). Overall, Se-Met attenuated K. pneumoniae-induced NF-κB-mediated inflammatory responses by enhancing autophagic flux.