Non-apoptotic cell death such as pyroptosis, autophagy, necroptosis and ferroptosis acts as partners to induce testicular cell death after scrotal hyperthermia in mice

Mechanism of mitochondrial oxidative phosphorylation disorder in male infertility

ABSTRACT

Male infertility has become a global concern, accounting for 20-70% of infertility. Dysfunctional spermatogenesis is the most common cause of male infertility; thus, treating abnormal spermatogenesis may improve male infertility and has attracted the attention of the medical community. Mitochondria are essential organelles that maintain cell homeostasis and normal physiological functions in various ways, such as mitochondrial oxidative phosphorylation (OXPHOS). Mitochondrial OXPHOS transmits electrons through the respiratory chain, synthesizes adenosine triphosphate (ATP), and produces reactive oxygen species (ROS). These mechanisms are vital for spermatogenesis, especially to maintain the normal function of testicular Sertoli cells and germ cells. The disruption of mitochondrial OXPHOS caused by external factors can result in inadequate cellular energy supply, oxidative stress, apoptosis, or ferroptosis, all inhibiting spermatogenesis and damaging the male reproductive system, leading to male infertility. This article summarizes the latest pathological mechanism of mitochondrial OXPHOS disorder in testicular Sertoli cells and germ cells, which disrupts spermatogenesis and results in male infertility. In addition, we also briefly outline the current treatment of spermatogenic malfunction caused by mitochondrial OXPHOS disorders. However, relevant treatments have not been fully elucidated. Therefore, targeting mitochondrial OXPHOS disorders in Sertoli cells and germ cells is a research direction worthy of attention. We believe this review will provide new and more accurate ideas for treating male infertility.

Nanodrugs based on co-delivery strategies to combat cisplatin resistance

Cisplatin (CDDP), as a broad-spectrum anticancer drug, is able to bind to DNA and inhibit cell division. Despite the widespread use of cisplatin since its discovery, cisplatin resistance developed during prolonged chemotherapy, similar to other small molecule chemotherapeutic agents, severely limits its clinical application. Cisplatin resistance in cancer cells is mainly caused by three reasons: DNA repair, decreased cisplatin uptake/increased efflux, and cisplatin inactivation. In earlier combination therapies, the emergence of multidrug resistance (MDR) in cancer cells prevented the achievement of the desired therapeutic effect even with the accurate combination of two chemotherapeutic drugs. Therefore, combination therapy using nanocarriers for co-delivery of drugs is considered to be ideal for alleviating cisplatin resistance and reducing cisplatin-related toxicity in cancer cells. This article provides an overview of the design of cisplatin nano-drugs used to combat cancer cell resistance, elucidates the mechanisms of action of cisplatin and the pathways through which cancer cells develop resistance, and finally discusses the design of drugs and related carriers that can synergistically reduce cancer resistance when combined with cisplatin.

Research progress on the role of autophagy in the development of varicocele

Varicocele (VC) is a common cause of infertility in men. Pathophysiological changes caused by VC, such as testicular hypoxia, high temperatures, oxidative stress, abnormal reproductive hormones, and Cd accumulation, can induce autophagy, thus affecting the reproductive function in patients with this condition. Autophagy regulators can be classified as activators or inhibitors. Autophagy activators upregulate autophagy, reduce the damage to the testis and epididymis, inhibit spermatogenic cell apoptosis, and protect fertility. In contrast, autophagy inhibitors block autophagy and aggravate the damage to the reproductive functions. Therefore, elucidating the role of autophagy in the occurrence, development, and regulation of VC may provide additional therapeutic options for men with infertility and VC. In this review, we briefly describe the progress made in autophagy research in the context of VC.

Fluoride induces pyroptosis via IL-17A-mediated caspase-1/11-dependent pathways and Bifidobacterium intervention in testis

Fluoride, a ubiquitous environmental pollutant, poses a significant public health threat. Our previous study revealed a correlation between fluoride-induced testicular pyroptosis and male reproductive dysfunction. However, the underlying mechanism remains unclear. Wild-type and interleukin 17A knockout mice were exposed to sodium fluoride (100 mg/L) in deionized drinking water for 18 weeks. Bifidobacterium intervention (1 × 109 CFU/mL, 0.2 mL/day, administered via gavage) commenced in the 10th week. Sperm quality, testicular morphology, key pyroptosis markers, spermatogenesis key genes, IL-17A signaling pathway, and pyroptosis pathway related genes were determined. The results showed that fluoride reduced sperm quality, damaged testicular morphology, affected spermatogenesis, elevated IL-17A levels, and induced testicular pyroptosis. Bifidobacterium intervention alleviated adverse reproductive outcomes. Fluoride-activated testicular pyroptosis through both typical and atypical pathways, with IL-17A involvement. Bifidobacterium supplementation attenuated pyroptosis by downregulating IL-17A, inhibiting NLRP3 and PYRIN-mediated caspase-1 and caspase-11 dependent pathways in testis, thereby alleviating fluoride-induced male reproductive damage. In summary, this study uncovers the mechanism underlying fluorine-induced testicular pyroptosis and illustrates the novel protecting feature of Bifidobacterium against fluoride-induced harm to male reproduction, along with its potential regulatory mechanism. These results provide fresh perspectives on treating male reproductive dysfunction resulting from fluoride or other environmental toxins.

Therapeutic Effects of Exosome Therapy and Photobiomodulation Therapy on the Spermatogenesis Arrest in Male Mice After Scrotum Hyperthermia

Introduction: In men, several factors cause infertility, among which we can mention damage to sperm due to high temperature. So far, various treatments have been proposed for it, but they have not been highly effective. The current study aimed to evaluate the effect of exosome therapy (EXO) and photobiomodulation therapy (PBMT) on spermatogenesis arrest in male mice after scrotum hyperthermia. Methods: In this experimental study, the animals were divided into four groups: control, scrotal hyperthermia, scrotal hyperthermia+EXO (100 μL/d) (mice were treated for 30 days), scrotal hyperthermia+PBMT (laser of 0.03 J/cm2 for 30 seconds/for 30 days). Hyperthermia was induced by exposure to the temperature of 43 °C for 20 minute every day for 5 times. After 6 weeks, the animals were sacrificed. Results: The treated groups showed a significant increase in sperm parameters, as compared to the hyperthermic groups. Moreover, these favorable effects were observed in relation to the volume of testicular tissue, the number of germ cells, Leydig cells and Sertoli cells, and the level of testosterone. Research on antioxidants showed a significant reduction in oxidized glutathione (GSSG) and reactive oxygen species (ROS) in the treatment groups in comparison to the hyperthermia group (P<0.001). Also, there has been a significant increase in the amount of hydrogen peroxide enzyme observed in the hyperthermia group as opposed to the treatment group (P<0.001). Conclusion: These findings show that EXO and PBMT can improve spermatogenesis caused by hyperthermia, reduce ROS and GSSG, and increase glutathione (GSH) and sperm quality.

Emerging roles of ferroptosis in male reproductive diseases

Ferroptosis is a type of programmed cell death mediated by iron-dependent lipid peroxidation that leads to excessive lipid peroxidation in different cells. Ferroptosis is distinct from other forms of cell death and is associated with various diseases. Iron is essential for spermatogenesis and male reproductive function. Therefore, it is not surprising that new evidence supports the role of ferroptosis in testicular injury. Although the molecular mechanism by which ferroptosis induces disease is unknown, several genes and pathways associated with ferroptosis have been linked to testicular dysfunction. In this review, we discuss iron metabolism, ferroptosis, and related regulatory pathways. In addition, we analyze the endogenous and exogenous factors of ferroptosis in terms of iron metabolism and testicular dysfunction, as well as summarize the relationship between ferroptosis and male reproductive dysfunction. Finally, we discuss potential strategies to target ferroptosis for treating male reproductive diseases and provide new directions for preventing male reproductive diseases.

Identification of a novel pyroptosis-related gene signature in human spermatogenic dysfunction

PURPOSE

To reveal the underlying roles that pyroptosis-related genes (PRGs) played in human spermatogenic dysfunction.

METHODS

One discovery set and three validation sets were employed to inspect the previously reported 33 PRGs in the human testis with different status of spermatogenesis. PRGs that differentially expressed in all sets were considered as key differentially expressed pyroptosis-related genes (PR-DEGs). The relationships between key PR-DEGs and samples' clinicopathological, therapeutic, and immune patterns were respectively studied. Single-cell RNA sequencing (scRNS-seq) analyses were conducted to show the expression changes and related mechanisms of key PR-DEGs at a single-cell resolution.

RESULTS

CASP4 and GPX4 were identified as two key PR-DEGs. These two genes were significantly dysregulated in spermatogenic dysfunctional samples, but with opposite tendency. CASP4 was negatively correlated with Johnsen scores but positively correlated with follicle-stimulating hormone (FSH) levels (all p < 0.05), while GPX4 exhibited significant positive correlations with Johnsen scores and negative relevance with FSH. For treatments, both molecules showed a prospective value of being predictors for sperm retrieval surgeries. Moreover, CASP4 and GPX4 were potential immunoregulators in the testicular immune microenvironment and showed significant correlations to testicular macrophages and mast cell infiltration. In scRNA-seq analyses, GPX4 was highly expressed in germ cells, which therefore suffered a sharp reduction with the loss of germ cells in spermatogenic dysfunction. On the other hand, CASP4 were basically somatic cell-derived, and the proportion of CASP4-positive Leydig cells significantly increased in disease testes (p = 0.0001).

CONCLUSION

In all, we revealed two key PRGs of human testes that might be functional in spermatogenic dysfunction.

Exploring the application of sildenafil for high-fat diet-induced erectile dysfunction based on interleukin-18-mediated NLRP3/Caspase-1 signaling pathway

Background

Inflammation is a key risk factor for heart disease and has also been linked to erectile dysfunction (ED). Sildenafil is a phosphodiesterase type 5 inhibitor with a strong antioxidant effect. Interleukin (IL)-18 is a proinflammatory factor. Excessive production and release of IL-18 disrupt the balance between IL-18 and IL-18 binding proteins in certain inflammatory diseases, leading to the occurrence of pathological inflammation.

Aim

We evaluated the effects of sildenafil on erectile function in a rat model of high-fat diet-induced ED.

Methods

Male Sprague Dawley rats (6 weeks old) were divided into 5 groups: control, ED, sildenafil, IL-18, and IL-18 + sildenafil. Subsequently, intracavernous pressure and mean arterial pressure were used to assess the erectile function of these rats. The expression of endothelial nitric oxide synthase, pyroptosis factors, and the ratio of smooth muscle cells and collagen fibers were evaluated in the serum and corpora tissue.

Outcomes

Exploring the role and mechanism of sildenafil in ED through NLRP3-mediated pyroptosis pathway.

Results

In comparison to the ED and IL-18 groups, there were statistically significant increases in the ratio of intracavernous pressure to mean arterial pressure, endothelial nitric oxide synthase expression, and the ratio of smooth muscle cells to collagen fibers following sildenafil intervention (P < .05). The sildenafil group and IL-18 + sildenafil group also showed statistically significant decreases the expression of NLRP3, caspase-1, and gasdermin D (P < .05).

Clinical Implications

Sildenafil can improve erectile dysfunction by inhibiting inflammation.

Strengths and Limitations

Strengths are that the relationship between pyroptosis and ED has been verified through in vitro and in vivo experiments. The limitation is that the conclusions drawn from animal and cells experiments need to be confirmed in clinical research.

Conclusion

Sildenafil may reduce the effect of IL-18-induced inflammation in high-fat diet-induced ED rats through NLRP3/caspase-1 pyroptosis pathway.

Protective Effect of Curculigo orchioides Gaertn. Extract on Heat Stress-Induced Spermatogenesis Complications in Murine Model

Curculigo orchioides Gaertn. is a precious herb used in traditional medicine systems in Asian countries for various health benefits. This study investigated the potential protective effects of C. orchioides extract on reproductive health under heat stress conditions in male mice. Forty-eight mice were divided into eight groups, control condition (C group), C. orchioides extract at the dosages of 100, 200, and 400 mg/kg/day (C100, C200, C400 group), 40 °C heat exposure (H group), and combined 40 °C heat exposure and C. orchioides extract at the dosages of 100, 200, and 400 mg/kg/day (HC100, HC200, HC400 group). The result shows that the mice that received only C. orchioides extract without heat stress do not have a significant change in histological structure and testosterone level. The histological analysis of testicular tissue showed that heat stress conditions reduced reproductive function and inhibited the spermatogenesis of male mice. The C. orchioides rhizome extract treatment attenuated the heat stress-induced spermatogenesis complications in the murine model. Mice in the heat-stress group treated with C. orchioides extract had increased spermatogenic cells and spermatozoa compared with mice exposed to heat without C. orchioides treatment. Moreover, the aqueous extract of C. orchioides rhizome enhanced the serum total testosterone levels in heat-exposed mice. In conclusion, the study findings validate that C. orchioides is effective against heat stress-induced spermatogenesis complications in the murine model.

Bilateral varicocele leads to ferroptosis, pyroptosis and necroptosis of human spermatozoa and affects semen quality in infertile men

Purpose: This study explored the effects of bilateral varicocele on male semen quality in infertile men and the molecular mechanisms involving ferroptosis, pyroptosis and necroptosis signaling pathways. Methods: Totally, 20 healthy males and 26 patients with bilateral varicocele receiving infertility treatment were enrolled. Semen samples were collected. Basic semen parameters, acrosome integrity and membrane integrity, mitochondrial membrane potential (MMP) and apoptosis rate were compared. Levels of reactive oxygen species (ROS), iron, glutathione (GSH), total superoxide dismutase (T-SOD), and, Catalase (CAT), were detected in human seminal plasma. Relative mRNA expression of Ca ²⁺-independent phospholipases A2 beta (iPLA 2β), P53, Zinc finger E-box binding homeobox 1 (ZEB1) and GSH-dependent peroxidase 4 (GPX4) were evaluated. Relative protein expression was determined for GPX4, receptor interacting serine/threonine kinase 1 (RIPK1) and receptor interacting serine/threonine kinase 3 (RIPK3), as well as pyroptosis markers of Gasdermin E (GSDME) and heat shock protein 90 (HSP 90). Results: The results revealed that the bilateral varicocele group had significantly higher abnormalities (sperm progressive rate and sperm motility) compared to the control group. Meanwhile, compared to control group, GSH, T-SOD, and CAT levels were reduced in the bilateral varicocele group (p < 0.05). However, the level of ROS and iron were significantly increased (p < 0.05). Relative mRNA expression of P53, iPLA 2β, ZEB1, and GPX4 were reduced. In addition, ROS exposure activated ferroptosis-related signal pathways. RIPK1, RIPK3, GSDME and HSP 90 were increased in bilateral varicocele group. ROS exposure affected signaling pathways related to ferroptosis, necrosis and pyroptosis in human spermatozoa. Conclusion: Bilateral varicocele leads to ferroptosis, pyroptosis and necroptosis of human spermatozoa and affects semen quality in infertile men.

Review of the Role of Ferroptosis in Testicular Function

Iron is an important metal element involved in the regulation of male reproductive functions and has dual effects on testicular tissue. A moderate iron content is necessary to maintain testosterone synthesis and spermatogenesis. Iron overload can lead to male reproductive dysfunction by triggering testicular oxidative stress, lipid peroxidation, and even testicular ferroptosis. Ferroptosis is an iron-dependent form of cell death that is characterized by iron overload, lipid peroxidation, mitochondrial damage, and glutathione peroxidase depletion. This review summarizes the regulatory mechanism of ferroptosis and the research progress on testicular ferroptosis caused by endogenous and exogenous toxicants. The purpose of the present review is to provide a theoretical basis for the relationship between ferroptosis and male reproductive function. Some toxic substances or danger signals can cause male reproductive dysfunction by inducing testicular ferroptosis. It is crucial to deeply explore the testicular ferroptosis mechanism, which will help further elucidate the molecular mechanism of male reproductive dysfunction. It is worth noting that ferroptosis does not exist alone but rather coexists with other forms of cell death (such as apoptosis, necrosis, and autophagic death). Alleviating ferroptosis alone may not completely reverse male reproductive dysfunction caused by various risk factors.

Evaluation of a single dose of intra-testicular insulin treatment in heat-stressed mice model

Insulin plays important role in testicular functions such as germ cell proliferation and steroidogenesis, despite its conventional role as a hypoglycaemic agent. It is also well known that testicular activity is severely get affected by heat stress and heat stress induces testicular pathogenesis. The effect of insulin on heat-induced testicular impairment has not been investigated. Thus, it is hypothesized that insulin might modulate testicular activity in a heat-stressed model. Experimental mice were separated into 4 groups; the first group was the normal control (CN), and the second group was subjected to heat stress (HS) by submerging the lower body part in a thermostatically controlled water bath maintained at 43°C for 15 min. The third and fourth groups were treated with a single dose of intra-testicular insulin (0.6 IU/mice) before and after heat stress. Animal tissue samples were collected after 14 days of heat treatment. Insulin treatment did not improve the sperm parameters; however, both insulin pre and post-treatment improved the markers of spermatogenesis such as Johnsen score, germinal epithelium height and the number of stages VII/VIII. The histoarchitecture of testis also showed amelioration from heat-induced pathogenesis in the insulin-treated groups. Insulin treatment has also increased the proliferation of germ cells (increased PCNA and GCN), survival (Bcl2), and decreased apoptosis (active caspase-3). Furthermore, insulin treatment decreased MDA levels, without pronounced effects on the activities of antioxidant enzymes. Heat stress also decreased the circulating testosterone and oestrogen levels, and insulin treatment significantly increased oestrogen levels only. Although testosterone showed an increasing trend, it was insignificant. The expression of aromatase, AR, ER-α, and ER-β was down regulated by heat-stress and insulin treatment up regulated these markers. In conclusion, our results showed the amelioration of heat-induced testicular impairment by pre and post-intra-testicular insulin treatments. Insulin-associated improvements in the pre-and post-treatment groups suggested a preventive mechanism of insulin against heat stress in the testis.