Seminal inflammasome activity in the adult varicocele

Chlorogenic acid can improve spermatogenic dysfunction in rats with varicocele by regulating mitochondrial homeostasis and inhibiting the activation of NLRP3 inflammasomes by oxidative mitochondrial DNA and cGAS/STING pathway

In recent years, Varicocele (VC) has been recognized as a common cause of male infertility that can be treated by surgery or drugs. How to reduce the damage of VC to testicular spermatogenic function has attracted extensive attention in recent years. Among them, overexpressed ROS and high levels of inflammation may play a key role in VC-induced testicular damage. As the key mediated innate immune pathways, cGAS-STING shaft under pathological conditions, such as in cell and tissue damage stress can be cytoplasmic DNA activation, induce the activation of NLRP3 inflammatory corpuscle, triggering downstream of the inflammatory cascade reaction. Chlorogenic acid (CGA), as a natural compound from a wide range of sources, has strong anti-inflammatory and antioxidant activities, and is a potential effective drug for the treatment of varicocele infertility. The aim of this study is to investigate the role of CGA in the spermatogenic dysfunction of the rat testis induced by VC and the potential mechanisms. The results of this study have shown that CGA gavage treatment ameliorated the pathological damage of seminiferous tubules, increased the number of sperm in the lumen, and increased the expression levels of Occludin and ZO-1, which indicated the therapeutic effect of CGA on spermatogenic dysfunction in the testis of VC rats. Meanwhile, the damage of mitochondrial structure was alleviated and the expression levels of ROS, NLRP3 and pro-inflammatory cytokines (IL-1β, IL-6, IL-18) were significantly reduced in the testicular tissues of model rats after CGA treatment. In addition, we demonstrated for the first time the high expression status of cGAS and STING in testicular tissues of VC model rats, and this was ameliorated to varying degrees after CGA treatment. In conclusion, this study suggests that CGA can improve the spermatogenic function of the testis by reducing mitochondrial damage and inhibiting the activation of the cGAS-STING axis, inhibiting the activation of the NLRP3 inflammasome, and improving the inflammatory damage of the testis, highlighting the potential of CGA as a therapeutic agent for varicocele infertility.

Effect of varicocele and varicocelectomy on sperm deoxyribonucleic acid fragmentation rates in infertile men with clinical varicocele

Varicocele is the leading cause of male infertility. It can affect sperm quantity and quality through various non-mutually exclusive pathophysiological mechanisms, mainly oxidative stress. Excessive production of reactive oxygen species may overwhelm the sperm's defenses against oxidative stress and harm the sperm's DNA. Excessive sperm DNA breaks, so-called sperm DNA fragmentation, result from the oxidative stress cascade and are commonly found in the ejaculates of men with varicocele and fertility-related issues. Measuring sperm DNA fragmentation can provide valuable information on the extent of harm and might help select candidates for surgical treatment. Varicocelectomy is beneficial for alleviating oxidative stress-associated infertility and improving sperm DNA integrity. However, reproductive outcomes of infertile men with elevated sperm DNA fragmentation rates and surgically treated varicoceles remain poorly studied, and there is a need for well-designed trials to determine the impact of sperm DNA fragmentation reduction on natural and medically assisted reproduction.

A review of the pathophysiology and evidence-based management of varicoceles and pelvic congestion syndrome

Pelvic congestion syndrome (PCS) in females and varicoceles in males may be regarded as closely related conditions since the main pathophysiological cause for both processes is pelvic venous insufficiency. Varicoceles are more prevalent amongst sub-fertile males, with an approximate incidence of 15% in the general male population. PCS is commonly diagnosed amongst premenopausal multiparous women, representing one of the leading causes of chronic pelvic pain. Both conditions appear to be predominantly left-sided and are associated with oxidative stress and pro-inflammatory cascades with subsequent effects on fertility. Clinical examination and pelvic ultrasonography play an essential role in the assessment of varicoceles, PCS and chronic pelvic pain. Venography is generally considered as a gold-standard procedure for both conditions. There is still much debate on how these conditions should be managed. This review article provides a comparative analysis of the underlying pathophysiological mechanisms of both PCS and varicoceles, their impact on fertility, as well as their clinical management.

Insight into inflammation involvement in varicocele: A narrative review

BACKGROUND

Varicocele is one of the main causes of male infertility. Although the pathophysiology mechanism of varicocele is very well described and understood, there are some unanswered questions that remains unknown. Some studies have previously described the state of testicular inflammation and sperm in animal models, especially the mouse model, and the seminal plasma of men with varicocele, with or without changes in semen parameters.

METHODS OF STUDY

This review intended to verify the role of inflammatory mechanism in varicocele, using clinical studies as well as animal model studies on the effect of inflammation caused by varicocele on the function of testicular somatic and germ cells.

RESULTS

In-vivo studies confirmed whether anti-inflammatory molecules could treat the semen of men with varicocele and rats with varicocele. The use of different anti-inflammatory agents in mouse model studies provided a new perspective for future clinical studies to investigate the effect of concurrent treatment with surgery to improve surgical outcomes.

CONCLUSION

Similar to animal model studies, previously conducted clinical trials have demonstrated the effectiveness of anti-inflammatory therapy in varicocele patients. However, clinical trials using anti-inflammatory are needed to be conducted agents to evaluate different aspects of this therapeutical approach in varicocele patients.

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.

Insight toward inflammasome complex contribution to male infertility

During the last decades, a wide range of factors involved in the physiopathology of male infertility disease have been discussed. The inflammation role in some of the main infertility-related diseases has been studied, such as varicocele, spinal cord injury and obesity. Inflammation is the main response of the immune system to infection or cell damage, leading to intense inflammatory cytokine release during the loss of homeostasis. One of the first steps toward pro-inflammatory cytokines release is the recognition of dangerous signals by the immune cells, including pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). These molecules can activate an important multiprotein complex, called inflammasome. Although these complexes have been studied during the last decades, their participation in male infertility has gained attention recently. Considering the inflammasome complex's high potential to be targeted for drug therapy, this review tries to shed light on current literature. Therefore, in the current review paper, we aimed to discuss the inflammasome complex activation, involvement in different male infertility conditions, and localization in the male reproductive tract.

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.

The Effect of Statins on Male Reproductive Parameters: A Mechanism Involving Dysregulation of Gonadal Hormone Receptors and TRPV1

Statins have been shown to cause diverse male reproductive function impairment, and in some cases, orchialgia. Therefore, the current study investigated the possible mechanisms through which statins may alter male reproductive parameters. Thirty adult male Wistar rats (200-250 g) were divided into three groups. The animals were orally administered rosuvastatin (50 mg/kg), simvastatin (50 mg/kg), or 0.5% carboxy methyl cellulose (control), for a 30-day period. Spermatozoa were retrieved from the caudal epididymis for sperm analysis. The testis was used for all biochemical assays and immunofluorescent localization of biomarkers of interest. Rosuvastatin-treated animals presented with a significant decrease in sperm concentration when compared to both the control and simvastatin groups (p < 0.005). While no significant difference was observed between the simvastatin and the control group. The Sertoli cells, Leydig cells and whole testicular tissue homogenate expressed transcripts of solute carrier organic anion transporters (SLCO1B1 and SLCO1B3). There was a significant decrease in the testicular protein expression of the luteinizing hormone receptor, follicle stimulating hormone receptor, and transient receptor potential vanilloid 1 in the rosuvastatin and simvastatin-treated animals compared to the control. The expression of SLCO1B1, SLCO1B2, and SLCO1B3 in the different spermatogenic cells portray that un-bio transformed statin can be transported into the testicular microenvironment, which can subsequently alter the regulation of the gonadal hormone receptors, dysregulate pain-inflammatory biomarkers, and consequently impair sperm concentration.

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.

Silencing CAMK2D Promotes the Proliferation of Spermatogonia in the Testis of Experimental Varicocele Rats

Varicocele is regarded as the main factor that contributes to male infertility. This study aimed to explore the effect of CAMK2D on spermatogonia in the testis of experimental varicocele rats. The experimental varicocele model was established in rats and treated using different ligation methods. mRNA expression profile analysis was performed on the left testicular tissue isolated from different groups, and differentially expressed genes (DEGs) were analysed by bioinformatics methods and identified by qRT-PCR. The effect of CAMK2D, the screened DEG, on the proliferation of spermatogonia was evaluated by CCK-8 assay. The expression level of the c-kit was measured by the immunofluorescence assay and the expression levels of CAMKII, FOXO1, and β-catenin were detected by qRT-PCR and western blotting. Five DEGs (i.e., TMCC3, FLNB, CAMK2D, OPLAH, and EGR1) were screened using the comprehensive analysis of mRNA high-throughput sequencing data. TMCC3 and FLNB were significantly downregulated, and CAMK2D, OPLAH, and EGR1 were dramatically upregulated in the testicular tissue of varicocele rats. The target DEG CAMK2D was obtained through identification by using qRT-PCR. In vitro assays revealed that the proliferation of spermatogonia was significantly facilitated by the silencing of CAMK2D, which resulted in the downregulation of CAMKII, FOXO1, and β-catenin. In conclusion, silencing CAMK2D facilitated the proliferation of spermatogonia in the testis of experimental varicocele rats.

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.

Long noncoding RNAs regulated spermatogenesis in varicocele-induced spermatogenic dysfunction

Objectives

To evaluate the expression, potential functions and mechanisms of long noncoding RNAs (lncRNAs) in the pathogenesis of varicocele (VC)‐induced spermatogenic dysfunction.

Materials and Methods

We established a rat model with left experimental VC and divided rats into the sham group, the VC group, and the surgical treatment group (each group, n = 10). Haematoxylin and eosin (HE) staining and sperm quality were analysed to evaluate spermatogenesis function. LncRNA expression profiles were analysed using lncRNA‐Seq (each group n = 3) and validated using quantitative real‐time polymerase chain reaction (each group n = 10). Correlation analysis and gene target miRNA prediction were used to construct competing endogenous RNA network. The regulated signalling pathway and spermatogenic dysfunction of differentially expressed lncRNAs (DE lncRNAs) were validated by Western blot.

Results

HE detection and sperm quality analysis showed that VC could induce spermatogenic dysfunction. Eight lncRNAs were upregulated and three lncRNAs were downregulated in the VC group compared with the sham group and surgical treatment group. The lncRNA of NONRATG002949.2, NONRATG001060.2, NONRATG013271.2, NONRATG022879.2, NONRATG023424.2, NONRATG005667.2 and NONRATG010686.2 were significantly negatively related to sperm quality, while NONRATG027523.1, NONRATG017183.2 and NONRATG023747.2 were positively related to sperm quality. The lncRNAs promote spermatogenic cell apoptosis and inhibit spermatogonia and spermatocyte proliferation and meiotic spermatocytes by regulating the PI3K–Akt signalling pathway.

Conclusion

DE lncRNAs may be potential biomarkers for predicting the risk of spermatogenic dysfunction in VC and the effect of surgical repair. These DE lncRNAs promote spermatogenic dysfunction by regulating the PI3K–Akt signalling pathway.

Effect of varicocele on sperm DNA damage: A systematic review and meta-analysis

The updated meta-analysis was conducted to further verify the effect of varicocele on sperm DNA damage, supplying clinicians and researchers with high-grade evidence. The sperm DNA damage was evaluated by DNA fragmentation index (DFI), associated with the male fertility capability tightly. PubMed, Web of Science and Cochrane Library were searched extensively for eligible studies with the search terms: varicocele, sperm DNA and sperm DNA damage. Finally, a total of 12 studies were included in our meta-analysis with a total of 845 patients diagnosed with varicocele and 2,377 healthy controls. A statistical difference of DFI between varicocele patients and healthy controls was found after pooling the data ((Standardised mean difference) SMD: 1.40, 95%CI: 0.83-1.98, p < .0001), using the random effect model. We conducted subgroup analysis according to study region (Brazil and Other countries), detection methods of DFI (TUNEL, Comet, and SCSA), sample size (<50 and >50) and age (<30 and >30 years), based on substantial heterogeneity among eligible studies. The stability of pooled results was verified by sensitivity analysis. All these statistical analyses were conducted using Stata version 16.0. In conclusion, patients diagnosed with clinical varicocele had higher DFI than healthy controls, which means varicocele could impair sperm DNA, consequently the fertility potential of affected men.

The Negative Impact of Varicocele on Basic Semen Parameters, Sperm Nuclear DNA Dispersion and Oxidation-Reduction Potential in Semen

Since varicocele is so common in infertile men, this study intends to analyse the relationships between varicocele and conventional semen characteristics, sperm nuclear DNA dispersion and oxidation-reduction potential (ORP) in semen. Varicocele-positive and varicocele-negative infertile men (study groups) showed significantly lower standard sperm parameters and higher sperm DNA fragmentation (SDF) and ORP in semen than healthy volunteers and subjects with proven fertility (control groups). A lower proportion of low SDF levels (0–15% SDF) and higher incidence of high SDF levels (>30% SDF), as well as a higher prevalence of high ORP values (>1.37 mV/10⁶ sperm/mL), were found in the study groups vs. the control groups. Moreover, infertile men had significantly lower odds ratios (ORs) for low SDF levels and significantly higher ORs for high SDF levels and high ORP. SDF and ORP were negatively correlated with sperm number, morphology, motility and vitality. Furthermore, a significant positive correlation was found between SDF and ORP. The obtained results suggest that disorders of spermatogenesis may occur in varicocele-related infertility. These abnormalities are manifested not only by reduced standard semen parameters but also by decreased sperm DNA integrity and simultaneously increased oxidative stress in semen.