The Role of NLRP3 Inflammasome Activation and Oxidative Stress in Varicocele-Mediated Male Hypofertility

Type 1 diabetes impairs the activity of rat testicular somatic and germ cells through NRF2/NLRP3 pathway-mediated oxidative stress

Background

It is well known that metabolic disorders, including type 1 diabetes (T1D), are often associated with reduced male fertility, mainly increasing oxidative stress and impairing the hypothalamus-pituitary-testis (HPT) axis, with consequently altered spermatogenesis and reduced sperm parameters. Herein, using a rat model of T1D obtained by treatment with streptozotocin (STZ), we analyzed several parameters of testicular activity.

Methods

A total of 10 adult male Wistar rats were divided into two groups of five: control and T1D, obtained with a single intraperitoneal injection of STZ. After 3 months, the rats were anesthetized and sacrificed; one testis was stored at -80°C for biochemical analysis, and the other was fixed for histological and immunofluorescence analysis.

Results

The data confirmed that T1D induced oxidative stress and, consequently, alterations in both testicular somatic and germ cells. This aspect was highlighted by enhanced apoptosis, altered steroidogenesis and Leydig cell maturity, and impaired spermatogenesis. In addition, the blood-testis barrier integrity was compromised, as shown by the reduced levels of structural proteins (N-cadherin, ZO-1, occludin, connexin 43, and VANGL2) and the phosphorylation status of regulative kinases (Src and FAK). Mechanistically, the dysregulation of the SIRT1/NRF2/MAPKs signaling pathways was proven, particularly the reduced nuclear translocation of NRF2, affecting its ability to induce the transcription of genes encoding for antioxidant enzymes. Finally, the stimulation of testicular inflammation and pyroptosis was also confirmed, as highlighted by the increased levels of some markers, such as NF-κB and NLRP3.

Conclusion

The combined data allowed us to confirm that T1D has detrimental effects on rat testicular activity. Moreover, a better comprehension of the molecular mechanisms underlying the association between metabolic disorders and male fertility could help to identify novel targets to prevent and treat fertility disorders related to T1D.

The role of hydrogen sulfide regulation of pyroptosis in different pathological processes

Pyroptosis is one kind of programmed cell death in which the cell membrane ruptures and subsequently releases cell contents and pro-inflammatory cytokines including IL-1β and IL-18. Pyroptosis is caused by many types of pathological stimuli, such as hyperglycemia (HG), oxidative stress, and inflammation, and is mediated by gasdermin (GSDM) protein family. Increasing evidence indicates that pyroptosis plays an important role in multiple diseases, such as cancer, kidney diseases, inflammatory diseases, and cardiovascular diseases. Therefore, the regulation of pyroptosis is crucial for the occurrence, development, and treatment of many diseases. Hydrogen sulfide (H2S) is a biologically active gasotransmitter following carbon monoxide (CO) and nitrogen oxide (NO) in mammalian tissues. So far, three enzymes, including 3-mercaptopyruvate sulphurtransferase (3-MST), cystathionine γ- Lyase (CSE), and Cystine β-synthesis enzyme (CBS), have been found to catalyze the production of endogenous H2S in mammals. H2S has been reported to have multiple biological functions including anti-inflammation, anti-oxidative stress, anti-apoptosis and so on. Hence, H2S is involved in various physiological and pathological processes. In recent years, many studies have demonstrated that H2S plays a critical role by regulating pyroptosis in various pathological processes, such as ischemia-reperfusion injury, alcoholic liver disease, and diabetes cardiomyopathy. However, the relevant mechanism has not been completely understood. Therefore, elucidating the mechanism by which H2S regulates pyroptosis in diseases will help understand the pathogenesis of multiple diseases and provide important new avenues for the treatment of many diseases. Here, we reviewed the progress of H2S regulation of pyroptosis in different pathological processes, and analyzed the molecular mechanism in detail to provide a theoretical reference for future related research.

Resatorvid alleviates experimental inflammatory TMJOA by restraining chondrocyte pyroptosis and synovial inflammation

OBJECTIVES

Innate immunity plays a significant role in the pathogenesis of temporomandibular joint osteoarthritis (TMJOA), which is characterized by synovial inflammation and condylar cartilage degradation. We are urged to investigate the impact of Resatorvid, a preventative drug that inhibits Toll-like receptor 4 (TLR4), on experimental inflammatory TMJOA pathology.

METHODS

An intra-articular injection of complete Freund's adjuvant (CFA) was used to induce an experimental inflammatory mouse TMJOA model, and TLR4 expression was identified by immunofluorescent labeling. Intraperitoneal injections of Resatorvid were administered to CFA-induced TMJOA mice, and the pathology of TMJOA animals with and without Resatorvid treatment was examined by H&E, Safranin-O/Fast Green, and TRAP staining, as well as micro-CT, immunohistochemistry, and immunofluorescence. The impact of Resatorvid on chondrocyte pyroptosis and macrophage inflammation was further investigated using ATDC5 chondrocytes and RAW264.7 macrophages pretreated with relevant antagonists.

RESULTS

CFA-induced TMJOA mice revealed remarkable synovial inflammation, together with a time course of cartilage degradation and bone destruction, with TLR4 elevated in the synovium and condylar cartilage. Prophylactic treatment with Resatorvid mitigated synovial inflammation, cartilage degeneration, and bone destruction in CFA-induced TMJOA mice and downregulated MyD88/NF-κB expression. Ex vivo studies demonstrated that Resatorvid treatment alleviated NOD-like receptor protein 3 (NLRP3)-mediated chondrocyte pyroptosis and degeneration and relieved macrophage inflammation by preventing reactive oxygen species (ROS) production through NLRP3 signaling.

CONCLUSION

Prophylactic treatment with Resatorvid alleviates TMJOA pathology by inhibiting chondrocyte pyroptosis and degeneration, as well as ROS-induced macrophage inflammation, through TLR4/MyD88/NF-κB/NLRP3.

Inflammasomes in human reproductive diseases

Inflammasomes are multi-protein complexes localized within immune and non-immune cells that induce caspase activation, proinflammatory cytokine secretion, and ultimately pyroptosis-a type of cell death. Inflammasomes are involved in a variety of human diseases, especially acute or chronic inflammatory diseases. In this review, we focused on the strong correlation between the NLRP3 inflammasome and various reproductive diseases, including ovarian aging or premature ovarian insufficiency, PCOS, endometriosis, recurrent spontaneous abortion, preterm labor, pre-eclampsia, and male subfertility, as well as the multifaceted role of NLRP3 in the pathogenesis and treatment of these diseases. In addition, we provide an overview of the structure and amplification of inflammasomes. This comprehensive review demonstrates the vital role of NLRP3 inflammasome activation in human reproductive diseases together with the underlying mechanisms, offers new insights for mechanistic studies of reproduction, and provides promising possibilities for the development of drugs targeting the NLRP3 inflammasome for the treatment of reproductive disorders in the future.

Specnuezhenide ameliorates ultraviolet-induced skin photoaging in mice by regulating the Sirtuin 3/8-Oxoguanine DNA glycosylase signal

PURPOSE

Ultraviolet-induced skin photoaging was involved in DNA oxidative damage. Specnuezhenide, one of the secoiridoids extracted from Ligustri Lucidi Fructus, possesses antioxidant and anti-inflammatory effects. Whether specnuezhenide ameliorates skin photoaging remains unclear. This study aimed to investigate the effect of specnuezhenide on skin photoaging induced by ultraviolet and explore the underlying mechanism.

METHODS

Mice were employed to treat with ultraviolet to induce skin photoaging, then administrated 10 and 20 mg/kg of specnuezhenide. Histological analysis, protein expression, network pharmacology, and autodock analysis were conducted.

RESULTS

Specnuezhenide ameliorated ultraviolet-induced skin photoaging in mice via the increase in collagen contents, and decrease in epidermal thickness, malondialdehyde content, and β-galactosidase expression in the skin. Specnuezhenide reduced cutaneous apoptosis and inflammation in mice with skin photoaging. In addition, network pharmacology data indicated that specnuezhenide possessed potential targets on the NOD-like receptor signaling pathway. Validation experiment found that specnuezhenide inhibited the expression of NOD-like receptor family pyrin domain-containing 3, gasdermin D-C1, and Caspase 1. Furthermore, the expression of 8-Oxoguanine DNA glycosylase (OGG1), sirtuin 3 (SIRT3), and superoxide dismutase 2 was increased in specnuezhenide-treated mice with photoaging.

CONCLUSION

Specnuezhenide protected against ultraviolet-induced skin photoaging in mice via a probable activation of SIRT3/OGG1 signal.

Zishen Yutai Pill improves sperm quality and reduces testicular inflammation in experimental varicocele rats

Objective

Zishen Yutai Pill (ZYP), containing 15 Chinese traditional medicine, is a safe and well quality-controlled TCM preparation with promising effects in many fields of reproduction. The current study was designed to investigate the therapeutic effects of ZYP on sperm quality and testis in varicocele (VC) rats.

Materials and methods

Male Wistar rats were randomly divided into four groups (n = 6), i.e., a sham group, a VC group, and VC groups treated with different dose of ZYP (1575 and 3150 mg/kg/d, respectively). The experimental VC model was established by partial ligation of left renal vein. Six weeks after model establishment, ZYP was orally administered once a day for the next 6 weeks. Parameters relating to testis and sperm quality were assessed. Hematoxylin-eosin staining was used to showed testicular tissue damage in experimental VC rats. Expressions of proteins relating to NLRP3 inflammasome pathways were determined using Western blot (WB). The mRNA expressions of relating genes were determined using quantitative real-time PCR (qRT-PCR) analysis.

Results

ZYP could significantly improve sperm motility and decrease sperm DNA fragmentation index in VC rats (P < 0.05). Hematoxylin-eosin (HE) staining showed that ZYP could alleviate testicular tissue damage caused by experimental varicocele in rats. Compared to the VC model, expressions of NLRP3, ASC, and caspase-1 in rats treated with ZYP were significantly down-regulated, as validated by both qRT-PCR and WB analysis (P < 0.05).

Conclusions

In brief, ZYP could improve sperm DNA integrity by inhibiting the NLRP3 inflammasome pathway and alleviating the chronic inflammation of testicular tissue induced by experimental varicocele in rats.

Microbiology and immune mechanisms associated with male infertility

Up to 50% of infertility is caused by the male side. Varicocele, orchitis, prostatitis, oligospermia, asthenospermia, and azoospermia are common causes of impaired male reproductive function and male infertility. In recent years, more and more studies have shown that microorganisms play an increasingly important role in the occurrence of these diseases. This review will discuss the microbiological changes associated with male infertility from the perspective of etiology, and how microorganisms affect the normal function of the male reproductive system through immune mechanisms. Linking male infertility with microbiome and immunomics can help us recognize the immune response under different disease states, providing more targeted immune target therapy for these diseases, and even the possibility of combined immunotherapy and microbial therapy for male infertility.