Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin promotes inflammation in mouse testes: The critical role of Klotho in Sertoli cells

Anti-Inflammatory Role of the Klotho Protein and Relevance to Aging

The α-Klotho protein (hereafter Klotho) is an obligate coreceptor for fibroblast growth factor 23 (FGF23). It is produced in the kidneys, brain and other sites. Klotho insufficiency causes hyperphosphatemia and other anomalies. Importantly, it is associated with chronic pathologies (often age-related) that have an inflammatory component. This includes atherosclerosis, diabetes and Alzheimer's disease. Its mode of action in these diseases is not well understood, but it inhibits or regulates multiple major pathways. Klotho has a membrane form and a soluble form (s-Klotho). Cytosolic Klotho is postulated but not well characterized. s-Klotho has endocrine properties that are incompletely elucidated. It binds to the FGF receptor 1c (FGFR1c) that is widely expressed (including endothelial cells). It also attaches to soluble FGF23, and FGF23/Klotho binds to FGFRs. Thus, s-Klotho might be a roaming FGF23 coreceptor, but it has other functions. Notably, Klotho (cell-bound or soluble) counteracts inflammation and appears to mitigate related aging (inflammaging). It inhibits NF-κB and the NLRP3 inflammasome. This inflammasome requires priming by NF-κB and produces active IL-1β, membrane pores and cell death (pyroptosis). In accord, Klotho countered inflammation and cell injury induced by toxins, damage-associated molecular patterns (DAMPs), cytokines, and reactive oxygen species (ROS). s-Klotho also blocks the TGF-β receptor and Wnt ligands, which lessens fibrotic disease. Low Klotho is associated with loss of muscle mass (sarcopenia), as occurs in aging and chronic diseases. s-Klotho counters the inhibitory effects of myostatin and TGF-β on muscle, reduces inflammation, and improves muscle repair following injury. The inhibition of TGF-β and other factors may also be protective in diabetic retinopathy and age-related macular degeneration (AMD). This review examines Klotho functions especially as related to inflammation and potential applications.

Modulation of Ceramide-Induced Apoptosis in Enteric Neurons by Aryl Hydrocarbon Receptor Signaling: Unveiling a New Pathway beyond ER Stress

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a persistent organic pollutant and a potent aryl hydrocarbon receptor (AHR) ligand, causes delayed intestinal motility and affects the survival of enteric neurons. In this study, we investigated the specific signaling pathways and molecular targets involved in TCDD-induced enteric neurotoxicity. Immortalized fetal enteric neuronal (IM-FEN) cells treated with 10 nM TCDD exhibited cytotoxicity and caspase 3/7 activation, indicating apoptosis. Increased cleaved caspase-3 expression with TCDD treatment, as assessed by immunostaining in enteric neuronal cells isolated from WT mice but not in neural crest cell-specific Ahr deletion mutant mice (Wnt1Cre+/-/Ahrb(fl/fl)), emphasized the pivotal role of AHR in this process. Importantly, the apoptosis in IM-FEN cells treated with TCDD was mediated through a ceramide-dependent pathway, independent of endoplasmic reticulum stress, as evidenced by increased ceramide synthesis and the reversal of cytotoxic effects with myriocin, a potent inhibitor of ceramide biosynthesis. We identified Sptlc2 and Smpd2 as potential gene targets of AHR in ceramide regulation by a chromatin immunoprecipitation (ChIP) assay in IM-FEN cells. Additionally, TCDD downregulated phosphorylated Akt and phosphorylated Ser9-GSK-3β levels, implicating the PI3 kinase/AKT pathway in TCDD-induced neurotoxicity. Overall, this study provides important insights into the mechanisms underlying TCDD-induced enteric neurotoxicity and identifies potential targets for the development of therapeutic interventions.

The relationship between klotho, testosterone, and sexual health parameters among US adult men

BACKGROUND

Klotho is a pleotropic hormone involved in a multitude of biological processes necessary for healthy aging, and affords protection from adverse events such as cardiovascular disease, inflammation, and various cancers. Emerging evidence suggests that klotho is also an important component of biochemical pathways that regulate hormone balance, which may include those pathways governing testosterone production and men's sexual health, though data are limited and results are mixed.

OBJECTIVE

Using a cohort of 767 men from the NHANES 2015-2016 survey cycle, we set out to quantify the association between serum klotho levels and serum testosterone levels, as well as clinical markers of men's sexual health (e.g., testosterone:estrogen ratio, bioavailable testosterone, and free testosterone).

METHODS

Multivariable linear and logistic regression models while controlling for potential confounders were constructed to quantify the relationship between serum klotho and testosterone, as well as between serum klotho and odds of low testosterone (serum testosterone < 300 ng/dL).

RESULTS

A positive association was observed between serum klotho and testosterone (β = 0.18, p = 0.04). Serum klotho levels were also stratified into quartiles, and we observed statistically significant increases in testosterone for increasing quartile level of klotho using the first quartile as the reference group (β = 90.51, p = 0.001, β = 106.93, p = 0.002, β = 95.33, p = 0.03 for quartiles 2, 3, and 4, respectively). The average testosterone values by quartiles of klotho were 306.9 ng/dL, 390 ng/dL, 409.3 ng/dL, and 436.6 ng/dL, respectively. We modeled important proxies for sexual health including bioavailable and free testosterone, the testosterone:estradiol ratio, and C-reactive protein. Men in the second quartile of klotho had a significantly lower odds of an abnormal testosterone:estradiol ratio compared to the first quartile [OR = 0.18, 95% CI = (0.03, 0.98)].We observed null associations between continuous serum klotho and odds of low testosterone [OR = 1.0, 95% CI = (1.0, 1.0)], and when stratified by quartile, we observed a significant decrease in the odds of low testosterone for individuals in the second quartile of klotho compared to the first quartile [OR = 0.21, 95% CI = (0.05, 0.91)]. In addition, C-reactive protein was inversely associated with testosterone in men (β = - 4.65, p = 0.001), and inversely associated with quartiles of klotho (β = - 2.28, p = 0.04, β = - 2.22, p = 0.04, β = - 2.28, p = 0.03, for quartiles 2, 3, and 4, respectively).

CONCLUSION

Our findings support previous studies suggesting a role for klotho in testosterone levels and sexual function among men. Future studies are warranted to corroborate these findings, determine clinical significance, and elucidate potential mechanisms underlying these associations.

Angiotensin-(1-7) plays an important role in regulating spermatogenesis in Trachemys scripta elegans under salinity stress

Elevation in water salinity can threaten the spermatogenesis and fertility of freshwater animals. The role of the renin-angiotensin system (RAS) in regulating spermatogenesis has attracted considerable attention. Our previous study found that red-eared sliders (Trachemys scripta elegans), could survive in 10 PSU water for over 1 year. To understand the chronic impact of salinity on testicular spermatogenesis and underlying mechanisms, male T. s. elegans were subjected to treatment with water of 5 PSU and 10 PSU for a year, and spermatogenesis and regulation of the RAS signal pathway was assessed. Results showed induced inflammation in the testes of T. s. elegans in the 10 PSU group, as evidenced by a decrease in the number of testicular germ cells from 1586 to 943. Compared with the control group, the levels of proinflammatory genes, including TNF-α, IL-12A and IL-6 were elevated 3.1, 0.3, and 1.4 times, respectively, in animals exposed to 10 PSU water. Testicular antiapoptotic processes of T. s. elegans might involve the vasoactive peptide angiotensin-(1-7) in the RAS, as its level was significantly increased from 220.2 ng ml-1 in controls to 419.2 ng ml-1 in the 10 PSU group. As expected, specific inhibitor (A-779) for the Ang-(1-7) acceptor effectively prevented the salinity-induced upregulation of genes encoding anti-inflammatory and antiapoptotic factors (TGF-β1, Bcl-6) in the testis of the 10 PSU animals, whereas it promoted the upregulation of proinflammatory and proapoptotic factors (TNF-α, IL-12A, IL-6, Bax and caspase-3). Our data indicated that Ang-(1-7) attenuates the effect of salinity on inflammation and apoptosis of the testis in T. s. elegans. A new perspective to prevent salinity-induced testis dysfunction is provided.

Inhibition of the urea cycle by the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin increases serum ammonia levels in mice

The aryl hydrocarbon receptor is a ligand-activated transcription factor known for mediating the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. TCDD induces nonalcoholic fatty liver disease (NAFLD)-like pathologies including simple steatosis that can progress to steatohepatitis with fibrosis and bile duct proliferation in male mice. Dose-dependent progression of steatosis to steatohepatitis with fibrosis by TCDD has been associated with metabolic reprogramming, including the disruption of amino acid metabolism. Here, we used targeted metabolomic analysis to reveal dose-dependent changes in the level of ten serum and eleven hepatic amino acids in mice upon treatment with TCDD. Bulk RNA-seq and protein analysis showed TCDD repressed CPS1, OTS, ASS1, ASL, and GLUL, all of which are associated with the urea cycle and glutamine biosynthesis. Urea and glutamine are end products of the detoxification and excretion of ammonia, a toxic byproduct of amino acid catabolism. Furthermore, we found that the catalytic activity of OTC, a rate-limiting step in the urea cycle was also dose dependently repressed. These results are consistent with an increase in circulating ammonia. Collectively, the repression of the urea and glutamate-glutamine cycles increased circulating ammonia levels and the toxicity of TCDD.

Astragaloside IV Attenuates High-Glucose-Induced Impairment in Diabetic Nephropathy by Increasing Klotho Expression via the NF-κB/NLRP3 Axis

Objective

Deficiencies in klotho are implicated in various kidney dysfunctions including diabetic nephropathy (DN) related to inflammatory responses. Klotho is closely related to inflammatory responses and is a potential target for ameliorating kidney failure. Pyroptosis, an inflammatory form of programmed cell death, is reported to take part in DN pathogenesis recently. This study is aimed at exploring whether and how klotho inhibited podocyte pyroptosis and whether astragaloside IV (AS-IV) protect podocyte through the regulation of klotho.

Materials and Methods

SD rat model of DN and conditionally immortalized mouse podocytes exposed to high glucose were treated with AS-IV. Biochemical assays and morphological examination, cell viability assay, cell transfection, phalloidin staining, ELISA, LDH release assay, SOD and MDA detection, MMP assay, ROS level detection, flow cytometry analysis, TUNEL staining assay, PI/Hoechst 33342 staining, immunofluorescence assay, and western blot were performed to elucidate podocyte pyroptosis and to observe the renal morphology.

Results

The treatment of AS-IV can improve renal function and protect podocytes exposed to high glucose. Klotho was decreased, and AS-IV increased klotho levels in serum and kidney tissue of DN rats as well as podocytes exposed to high glucose. AS-IV can inhibit DN glomeruli pyroptosis in vivo. In vitro, overexpressed klotho and treatment with AS-IV inhibited pyroptosis of podocytes cultured in high glucose. Klotho knockdown promoted podocyte pyroptosis, and treatment with AS-IV reversed this effect. Furthermore, the overexpression of klotho and AS-IV reduces oxidative stress levels and inhibited NF-κB activation and NLRP3-mediated podocytes' pyroptosis which was abolished by klotho knockdown. In addition, both the ROS inhibitor NAC and the NF-κB pathway inhibitor PDTC can inhibit NLRP3 inflammasome activation. NLRP3 inhibitor MCC950 can inhibit pyroptosis of podocytes exposed to high glucose.

Conclusion

Altogether, our results demonstrate that the protective effect of AS-IV in upregulating klotho expression in diabetes-induced podocyte injury is associated with the inhibition of NLRP3-mediated pyroptosis via the NF-κB signaling pathway.

Embryonic 6:2 FTOH exposure causes reproductive toxicity by disrupting the formation of the blood-testis barrier in offspring mice

Previous studies have revealed nephrotoxicity, hepatotoxicity, subchronic developmental and reproductive toxicity in rats exposed to fluorotelomer alcohol (FTOH). However, the effects of embryonic 6:2 FTOH exposure on the reproductive system of offspring mice remain unclear. The purpose of this study is to explore the reproductive toxic effects of embryonic 6:2 FTOH exposure on offspring male mice and the related molecular mechanisms. Therefore, the pregnant mice were given corn oil or 6:2 FTOH by gavage from gestational days 12.5-21.5. The results demonstrated that embryonic 6:2 FTOH exposure resulted in disrupted testicular structure, low expression of tight junction protein between Sertoli cells (SCs), impaired blood-testis barrier (BTB) formation and maturation, reduced sperm viability and increased malformation, and induced testicular inflammation in the offspring of mice. Further in vitro studies showed that 6:2 FTOH treatment upregulated MMP-8 expression by activating AKT/NF-κB signaling pathway, which in turn enhanced occludin cleavage leading to the disruption of SCs barrier integrity. In summary, this study demonstrated that 6:2 FTOH exposure caused reproductive dysfunction in male offspring through disruption of BTB, which provided new insights into the effects of 6:2 FTOH exposure on the offspring.

Bisphenol A and 2,3,7,8-tetrachlorodibenzo-p-dioxin at non-cytotoxic doses alter the differentiation potential and cell function of rat adipose-stem cells

The possibility of chemical contamination is an important issue to consider when designing a cell therapy strategy. Both bisphenol A (BPA) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are among the most environmentally relevant endocrine disrupting chemicals (EDCs, compounds with a high affinity for adipose tissue) recently studied. Adipose-derived stem cells (ASCs) are mesenchymal stromal cells (MSCs) obtained from adipose tissue widely used in regenerative medicine to prevent and treat diseases in several tissues and organs. Although the experimental use of tissue-engineered constructs requires careful analysis for approval and implantation, there has been a recent increase in the number of approved clinical trials for this promising strategy. This study aimed to evaluate cell viability, apoptosis, DNA damage, and the adipogenic or osteogenic differentiation potential of rat adipose-derived stem cells (rASCs) exposed to previously established non-cytotoxic doses of BPA and TCDD in vitro. Results demonstrated that 10 μM of BPA and 10 nM of TCDD were able to significantly reduce cell viability, while all exposure levels resulted in DNA damage, although did not increase the apoptosis rate. According to the analysis of adipogenic differentiation, 1 μM of BPA induced the significant formation of oil droplets, suggesting an increased adipocyte differentiation, while both 10 μM of BPA and 10 nM of TCDD decreased adipocyte differentiation. Osteogenic differentiation did not differ among the treatments. As such, BPA and TCDD in the concentrations tested can modify important processes in rASCs such as cell viability, adipogenic differentiation, and DNA damage. Together, these findings prove that EDCs play an important role as contaminants, putatively interfering in cell differentiation and thus impairing the therapeutic use of ASCs.

Aryl hydrocarbon receptor: From pathogenesis to therapeutic targets in aging-related tissue fibrosis

Aging promotes chronic inflammation, which contributes to fibrosis and decreases organ function. Fibrosis, the excessive synthesis and deposition of extracellular matrix components, is the main cause of most chronic diseases including aging-related organ failure. Organ fibrosis in the heart, liver, and kidneys is the final manifestation of many chronic diseases. The aryl hydrocarbon receptor (AHR) is a cytoplasmic receptor and highly conserved transcription factor that is activated by a variety of small-molecule ligands to affect a wide array of tissue homeostasis functions. In recent years, mounting evidence has revealed that AHR plays an important role in multi-organ fibrosis initiation, progression, and therapy. In this review, we summarise the relationship between AHR and the pathogenesis of aging-related tissue fibrosis, and further discuss how AHR modulates tissue fibrosis by regulating transforming growth factor-β signalling, immune response, and mitochondrial function, which may offer novel targets for the prevention and treatment of this condition.

Ongoing Clinical Trials in Aging-Related Tissue Fibrosis and New Findings Related to AhR Pathways

Fibrosis is a pathological manifestation of wound healing that replaces dead/damaged tissue with collagen-rich scar tissue to maintain homeostasis, and complications from fibrosis contribute to nearly half of all deaths in the industrialized world. Ageing is closely associated with a progressive decline in organ function, and the prevalence of tissue fibrosis dramatically increases with age. Despite the heavy clinical and economic burden of organ fibrosis as the population ages, to date, there is a paucity of therapeutic strategies that are specifically designed to slow fibrosis. Aryl hydrocarbon receptor (AhR) is an environment-sensing transcription factor that exacerbates aging phenotypes in different tissues that has been brought back into the spotlight again with economic development since AhR could interact with persistent organic pollutants derived from incomplete waste combustion. In addition, gut microbiota dysbiosis plays a pivotal role in the pathogenesis of numerous diseases, and microbiota-associated tryptophan metabolites are dedicated contributors to fibrogenesis by acting as AhR ligands. Therefore, a better understanding of the effects of tryptophan metabolites on fibrosis modulation through AhR may facilitate the exploitation of new therapeutic avenues for patients with organ fibrosis. In this review, we primarily focus on how tryptophan-derived metabolites are involved in renal fibrosis, idiopathic pulmonary fibrosis, hepatic fibrosis and cardiac fibrosis. Moreover, a series of ongoing clinical trials are highlighted.

The NLRP3 inflammasome: molecular activation and regulation in spermatogenesis and male infertility; a systematic review

Background

Infertility related to varicocele, infections, metabolic dysfunctions, oxidative stress and environmental toxicants is also associated with inflammatory processes that ultimately lead to the activation of the inflammasome pathway (IP). IP is classically activated by DAMPs, MAMPs or LAMPs, which stand for Damage-, Microbe- or Lifestyle-Associated Molecular Patterns, respectively. The most important player in IP activation is the NLRP3 (NOD[Nuclear oligomerization domain]-, LRR[Leucine rich repeat]- and pyrin domain-containing protein 3) which functions as an intracellular sensor of D/M/L-AMPs resulting in activation of caspase-1, promotion of apoptosis, pyroptosis and generation of inflammatory cytokines. This review addresses the question of whether IP activation might be associated with male infertility situations.

Results & conclusions

We conducted a systematic review of articles published in the Google Scholar, and PubMed databases through October 2021. It turns out that inflammasome activation and its consequences including cytokine storms, apoptosis and pyroptosis could be associated with the reduced sperm count as well as the structural and functional sperm defects recorded in several situations associated with male infertility suggesting that anti-inflammatory therapeutic strategies could be possibly considered to restore male fertility in future research.

α-Tocopherol restores semen quality in rats exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

Background and Aim:

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent organic pollutant toxic to the human reproductive system. This study aimed to evaluate the effect of α-Tocopherol administration on the male fertility parameters of a rat model exposed to TCDD.

Materials and Methods:

Fifty healthy 12-week-old male rats were randomly divided into five groups. Rats in the control group were given corn oil twice daily in 4 h intervals. In the treatment groups, all rats were given TCDD at a dose of 700 ng/kg of body weight (BW)/day for 45 days. Four hours after receiving the TCDD, T0 rats were given corn oil, and T1, T2, and T3 rats were given α-Tocopherol at doses of 77, 140, and 259 mg/kg BW/day, respectively, for 45 days. On day 46, experimental animals were sacrificed to collect blood and testicular samples.

Results:

TCDD exposure decreased superoxide dismutase activity, plasma membrane integrity, Leydig cell count, sperm cell count, sperm viability and motility, and increased malondialdehyde levels, serum testosterone levels, and sperm morphological abnormalities. The administration of α-Tocopherol mitigated the effects of TCDD exposure, and the 140 and 259 mg/kg BW/day treatments returned those male fertility parameters to normal levels.

Conclusion:

The administration of 140 mg/kg BW/day α-Tocopherol restored male semen quality in rats exposed to TCDD. We found dynamics serum testosterone levels in rats exposed to TCDD that need to be further studied.

The ameliorative effect of melatonin on LPS-induced Sertoli cells inflammatory and tight junctions damage via suppression of the TLR4/MyD88/NF-κB signaling pathway in newborn calf

The blood-testicular barrier (BTB) is involved in spermatogenesis, protects sperm development, and plays a crucial role in the reproductive process. Tight junctions (TJs) between Sertoli cells (SCs) are the key structure of (BTB), and if its structure is damaged, BTB function is affected. The cellular inflammation caused by Gram-negative bacteria affects the structural integrity of TJs. Melatonin (MT) has anti-inflammatory effects; however, the effect of MT in newborn calf SCs is unknown. Therefore, this experiment studied the protective effect of MT. The results showed that LPS upregulated TLR4, MyD88, and NF-κB expressions, in turn, activated the TLR4/MyD88/NF-κB signaling pathway, produced a large amount of IL-6 and IL-1β, downregulated the expression of ZO-1 and Occludin, and reduced the viability of SCs, which resulted in the inflammatory response of SCs and damage of TJs. The addition of MT decreased TLR4, MyD88, and NF-κB expressions, it then inhibited the activation of TLR4/MyD88/NF-κB signaling pathway, downregulated the expression of IL-6 and IL-1β, upregulated the expression of ZO-1 and Occludin, and increased the cell viability, thereby alleviating the inflammatory response of SCs, and restored the TJs structure. Overall, our results reveal that MT can alleviate LPS-induced in newborn calf SCs Inflammation and TJs injury through TLR4/MyD88/NF-κB signaling pathway.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-induced suppression of immunity in THP-1-derived macrophages and the possible mechanisms

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a well-known immunotoxic environmental pollutant. However, most immunotoxicology studies of TCDD were based on the animal models and the inner mechanisms have just focused on a few genes/proteins. In this study, the immune functions of THP-1-derived macrophages was measured with in-vitro bioassays after 24-h exposure of TCDD including environmentally relevant concentrations. RNA-seq and Weighted Gene Co-expression Network Analysis were used to characterize the immunotoxicity molecular mechanisms. Our study is the first report on the TCDD-induced effects of cell adhesion, morphology, and multiple cytokines/chemokines production on THP-1 macrophages. After TCDD treatment, we observed an inhibited cell adherence, probably attributed to the suppressed mRNA levels of adhesion molecules ICAM-1, VCAM-1 and CD11b, and a decrease in cell pseudopodia and expression of F-actin. The inflammatory cytokines TNF-α, IL-10 and other 8 cytokines/chemokines regulating granulocytes/T cells and angiogenesis were disrupted by TCDD. Alternative splicing event was found to be a sensitive target for TCDD. Using WGCNA, we identified 10 hub genes (TNF, SRC, FGF2, PTGS2, CDH2, GNG11, BDNF, WNT5A, CXCR5 and RUNX2) highly relevant to these observed phenotypes, suggesting AhR less important in the effects TCDD have on THP-1 macrophages than in other cells. Our findings broaden the understanding of TCDD immunotoxicity on macrophages and provide new potential targets for clarifying the molecular mechanisms.

The effects of sacubitril/valsartan and ramipril on the male fertility in hypertensive rats

OBJECTIVE:

Renin angiotensinogen system (RAS) inhibitors, ramipril and sacubitril/valsartan are frequently used in the treatment of cardiovascular diseases. Although they are known as contraindicated during pregnancy in hypertensive women, there is not any outcome of their safety in male fertility after exposure to ramipril or sacubitril/valsartan. In this study, we aimed to evaluate the effects of ramipril and sacubitril/valsartan to highlight their safety in the male fertility in normotensive and hypertensive rats.

METHODS:

Adult male normotensive and dexamethasone-induced hypertensive rats were treated with sacubitril/valsartan, ramipril and saline for 18 days. Arterial blood pressures were verified using carotid artery cannulation. Male fertility parameters, including the testis weights, histopathologic scoring of the testis, sperm count, sperm motility, morphology, and serum testosterone levels, were analyzed in treated and nontreated normotensive/hypertensive rats.

RESULTS:

Sacubitril/valsartan or ramipril treatments did not reveal a significant difference in sperm production, testicular morphology, and radioimmunoassay of serum testosterone levels compared to the control group. However, sperm motility was significantly reduced in rats under RAS inhibition.

CONCLUSION:

This finding was likely mediated by the identification of Ang receptors in the tails of rat sperm given that Ang receptors may play a role in the modulation of sperm motility. Identification of RAS-related proteins involved in sperm motility may help to explain their roles in motility. Our data provide general safety evidence for the male fertilization ability after paternal sacubitril/valsartan and ramipril exposure.

Melatonin alleviates LPS-induced endoplasmic reticulum stress and inflammation in spermatogonial stem cells

Orchitis is one of the leading causes of male animal infertility and is associated with inflammatory reactions caused by the bacterium. It has been reported that there is a mutual coupling effect between endoplasmic reticulum stress (ERS) and inflammatory response. Our studies showed that lipopolysaccharide (LPS) could cause testicular damages, apoptosis, ERS, and inflammatory responses in spermatogonial stem cells (SSCs); ERS-related apoptosis proteins were activated and the expression of ERS genes was significantly upregulated; meanwhile, the expression of Toll-like receptor 4 and inflammation factors was apparently increased with LPS treatment. Moreover, melatonin (MEL) could rescue testicular damage, and significantly inhibited the expression of ERS-related apoptosis genes, ERS markers, and inflammatory factors in SSCs and MEL played repairing and anti-infection roles in LPS-induced testicular damage. Therefore, MEL may be used as a drug to prevent and control bacterial infections in male reproductive systems. However, the specific molecular mechanism of MEL to resist ERS and inflammatory response remains to be further studied.