Presence of The NLRP3 Inflammasome Components in Semen of Varicocele Patients

A comprehensive review on potential role of selenium, selenoproteins and selenium nanoparticles in male fertility

Selenium (Se), a component of selenoproteins and selenocompounds in the human body, is crucial for the development of male reproductive organs, DNA synthesis, thyroid hormone, metabolism, and defence against infections and oxidative damage. In the testis, it must exceed a desirable level since either a shortage or an overabundance causes aberrant growth. The antioxidant properties of selenium are essential for preserving human reproductive health. Selenoproteins, which have important structural and enzymatic properties, control the biological activities of Se primarily. These proteins specifically have a role in metabolism and a variety of cellular processes, such as the control of selenium transport, thyroid hormone metabolism, immunity, and redox balance. Selenium nanoparticles (SeNPs) are less hazardous than selenium-based inorganic and organic materials. Upon being functionalized with active targeting ligands, they are both biocompatible and capable of efficiently delivering combinations of payloads to particular cells. In this review, we discuss briefly the chemistry, structure and functions of selenium and milestones of selenium and selenoproteins. Next we discuss the various factors influences male infertility, biological functions of selenium and selenoproteins, and role of selenium and selenoproteins in spermatogenesis and male fertility. Furthermore, we discuss the molecular mechanism of selenium transport and protective effects of selenium on oxidative stress, apoptosis and inflammation. We also highlight critical contribution of selenium nanoparticles on male fertility and spermatogenesis. Finally ends with conclusion and future perspectives.

The time course of nod-like receptor family pyrin domain containing 3 inflammasome complex expressions in the testis tissue of an experimental varicocele rat model: An experimental study

Background

Varicocele is characterized by abnormal dilation of the testicular vein, which results in hypoxia, the accumulation of reactive oxygen species, and the production of proinflammatory cytokines. It seems that a group of cytosolic receptors named nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome, is activated and involved in the pathogenesis of varicocele.

Objective

We aim to determine the time course of NLRP3 inflammasome expression in the testis tissue following varicocele induction.

Materials and Methods

In this experimental study, 36 adult Wistar rats (8 wk, 200-250 gr) were used. For the varicocele induction, the left renal vein was partially ligated. The mRNA levels of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain, and caspase-1 were evaluated by real-time polymerase chain reaction at 1, 2, 4, 8, and 12 wk after varicocele induction.

Results

Results showed that the gene expression of NLRP3 inflammasome component including NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain, and caspase-1 did not alter during week 1, 2, 4, and 8 after operation (p = 0.09). 12 wk after varicocele induction, gene expression levels were significantly up-regulated (p = 0.02).

Conclusion

Our data provides clear evidence that varicocele stimulates inflammasome activation in the testis tissue 12 wk after the operation, and this time is required for investigating NLRP3 activity in the varicocele rat model.

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.

What is the impact of inflammasome mechanisms on male infertility?

BACKGROUND

Mechanisms to explain inflammation in male infertility of unknown cause are still being investigated. The inflammasome is a key regulator of innate immunity in the inflammatory response to infections. Our study aims to investigate the effects of varicocele on infertility, its relationship with antioxidant and inflammasome mechanisms, and how it could be guided in azoospermic or nonazoospermic patients.

METHODS

A cross-sectional cohort study was conducted at the department of urology in our university hospital. Eightyeight randomly selected men aged 20-45 admitted to our hospital because of infertility between September 2019 and July 2020 were included in the study. Patients were divided into four equal groups according to their clinical status, those with/without azoospermia and with/without varicocele. Blood and semen samples were taken from the patients. NOD-like receptor pyrin domain-containing 3 (NLRP3) and interleukin-1 beta (IL1β) and total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) levels were measured in serum and semen, and the groups were compared statistically.

RESULTS

Serum and semen NLRP3, IL1β, TAS, TOS, and OSI values of the patients with varicocele or azoospermia were significantlyhigher than those without either varicocele or azoospermia (p < 0.05). The oxidative stress markers TAS, TOS, and OSI values were significantly higher in the other groups than those without azoospermia and varicocele (p < 0.05).

DISCUSSION

Inflammasome mechanisms, such as NLRP3 and IL1-β molecules, may provide additional benefit in evaluating the need and benefit of surgical or medical treatment in infertility with and without vascular pathology and with and without azoospermia.

Is Parthanatos Involved in Varicocele?

Varicoceles (VCs) have received widespread attention as a primary factor affecting male fertility and a pathological condition that may lead to decreased sperm count and motility in patients. Many studies have shown that an imbalance of local antioxidant balance exists in patients with VC, leading to an obvious increase in the content of reactive oxygen species (ROS) and may cause reductive stress. Excessive ROS may aggravate spermatogenesis dysfunction and affect male fertility. Poly(ADP-ribose) polymerase (PARP) is an enzyme associated with DNA repair in eukaryotic cells, can be activated by DNA fragments with structural damage, and has been considered a DNA damage receptor in DNA damage repair and apoptosis. We built a rat model of VC and an oxidative damage model of a spermatocyte-derived cell line (GC-2 cells) induced by hydrogen peroxide to study the role of PARP1 in VC. Differentially expressed genes (DEGs) were obtained by RNA sequencing in the testes of VC rats. Analysis of DEGs revealed some genes with significantly altered expression, which were validated in rat and cell models. Immunofluorescence, real-time quantitative PCR analysis, Western blot, and flow cytometry were used to analyze the changes between the control group and the VC or hydrogen peroxide group. Overall, we found that PARP1 protein expression increased in VC rats and in the hydrogen peroxide-induced oxidative stress model of GC-2 cells. Parthanatos may be one of the factors leading to reduced reproductive capacity in VC patients. Our study provides novel insights into the mechanisms of male infertility induced by oxidative stress and provides a new therapeutic target for VC.

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.

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

Varicocele (VC) is the most common abnormality identified in men evaluated for hypofertility. Increased levels of reactive oxygen species (ROS) and reduced antioxidants concentrations are key contributors in varicocele-mediated hypofertility. Moreover, inflammation and alterations in testicular immunity negatively impact male fertility. In particular, NLRP3 inflammasome activation was hypothesized to lead to seminal inflammation, in which the levels of specific cytokines, such as IL-1β and IL-18, are overexpressed. In this review, we described the role played by oxidative stress (OS), inflammation, and NLRP3 inflammasome activation in VC disease. The consequences of ROS overproduction in testis, including inflammation, lipid peroxidation, mitochondrial dysfunction, chromatin damage, and sperm DNA fragmentation, leading to abnormal testicular function and failed spermatogenesis, were highlighted. Finally, we described some therapeutic antioxidant strategies, with recognized beneficial effects in counteracting OS and inflammation in testes, as possible therapeutic drugs against varicocele-mediated hypofertility.

COVID-19 Is a Multi-Organ Aggressor: Epigenetic and Clinical Marks

The progression of coronavirus disease 2019 (COVID-19), resulting from a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, may be influenced by both genetic and environmental factors. Several viruses hijack the host genome machinery for their own advantage and survival, and similar phenomena might occur upon SARS-CoV-2 infection. Severe cases of COVID-19 may be driven by metabolic and epigenetic driven mechanisms, including DNA methylation and histone/chromatin alterations. These epigenetic phenomena may respond to enhanced viral replication and mediate persistent long-term infection and clinical phenotypes associated with severe COVID-19 cases and fatalities. Understanding the epigenetic events involved, and their clinical significance, may provide novel insights valuable for the therapeutic control and management of the COVID-19 pandemic. This review highlights different epigenetic marks potentially associated with COVID-19 development, clinical manifestation, and progression.

Varicocele-Mediated Male Infertility: From the Perspective of Testicular Immunity and Inflammation

Background

Varicocele (VC) is present in 35 - 40% of men with infertility. However, current surgical and antioxidant treatments are not completely effective. In addition to oxidative stress, it is likely that other factors such as testicular immune microenvironment disorder contribute to irreversible testicular. Evidence suggests that VC is associated with anti-sperm antibodies (ASAs), spermatogenesis and testosterone secretion abnormalities, and testicular cytokine production. Moreover, inhibition of inflammation can alleviate VC-mediated pathogenesis. The normal function of the testis depends on its immune tolerance mechanism. Testicular immune regulation is complex, and many infectious or non-infectious diseases may damage this precision system.

Results

The testicular immune microenvironment is composed of common immune cells and other cells involved in testicular immunity. The former includes testicular macrophages, T cells, dendritic cells (DCs), and mast cells, whereas the latter include Leydig cells and Sertoli cells (SCs). In animal models and in patients with VC, most studies have revealed an abnormal increase in the levels of ASAs and pro-inflammatory cytokines such as interleukin (IL)-1 and tumor necrosis factor (TNF)-alpha in the seminal plasma, testicular tissue, and even peripheral blood. It is also involved in the activation of potential inflammatory pathways, such as the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing (NLRP)-3 pathway. Finally, the development of VC-mediated infertility (VMI) may be facilitated by abnormal permeability of proteins, such as claudin-11, that constitute the blood-testis barrier (BTB).

Conclusions

The testicular immune response, including the production of ASAs and inflammatory factors, activation of inflammatory pathways, and destruction of the BTB may be involved in the pathogenesis of VMI it is necessary to further explore how patient outcomes can be improved through immunotherapy.

The Nutraceutical N-Palmitoylethanolamide (PEA) Reveals Widespread Molecular Effects Unmasking New Therapeutic Targets in Murine Varicocele

Varicocele is an age-related disease with no current medical treatments positively impacting infertility. Toll-like receptor 4 (TLR4) expression is present in normal testis with an involvement in the immunological reactions. The role of peroxisome proliferator-activated receptor-α (PPAR-α), a nuclear receptor, in fertility is still unclear. N-Palmitoylethanolamide (PEA), an emerging nutraceutical compound present in plants and animal foods, is an endogenous PPAR-α agonist with well-demonstrated anti-inflammatory and analgesics characteristics. In this model of mice varicocele, PPAR-α and TLR4 receptors’ roles were investigated through the administration of ultra-micronized PEA (PEA-um). Male wild-type (WT), PPAR-α knockout (KO), and TLR4 KO mice were used. A group underwent sham operation and administration of vehicle or PEA-um (10 mg/kg i.p.) for 21 days. Another group (WT, PPAR-α KO, and TLR4 KO) underwent surgical varicocele and was treated with vehicle or PEA-um (10 mg/kg i.p.) for 21 days. At the end of treatments, all animals were euthanized. Both operated and contralateral testes were processed for histological and morphometric assessment, for PPAR-α, TLR4, occludin, and claudin-11 immunohistochemistry and for PPAR-α, TLR4, transforming growth factor-beta3 (TGF-β3), phospho-extracellular signal-Regulated-Kinase (p-ERK) 1/2, and nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) Western blot analysis. Collectively, our data showed that administration of PEA-um revealed a key role of PPAR-α and TLR4 in varicocele pathophysiology, unmasking new nutraceutical therapeutic targets for future varicocele research and supporting surgical management of male infertility.

Relationship Between Semen IL-6, IL-33 and Malondialdehyde Generation in Human Seminal Plasma and Spermatozoa

Cytokines are physiological seminal components and their abnormal levels, reported in different pathological conditions, negatively influence the sperm function. We analysed the relationship between interleukin (IL)-6 and IL-33 levels and lipid peroxidation (LPO), measured both in semen and sperm lysate, in 44 human semen samples. The semen analysis was performed following the WHO guidelines. Seminal IL-6 and IL-33 concentrations were assessed by ELISA and LPO was evaluated measuring malondialdehyde (MDA) both in seminal plasma and viable spermatozoa. Two small groups of patients with varicocele and infection were extrapolated from the cases analysed and the variables compared with those of a group of control. IL-33 levels were undetectable in all samples and IL-6 levels were positively correlated with both seminal and sperm MDA concentrations (p < 0.01) and negatively with sperm parameters (p < 0.01). Seminal and sperm MDA levels were both negatively correlated with sperm parameters (p < 0.01). IL-6 and semen MDA showed an exponential positive relationship, whereas MDA values measured in viable spermatozoa were low until IL-6 amount reached a concentration of >30 pg/mL, rising consistently. By comparing the variables in the groups, we confirmed that a high IL-6 concentration in the varicocele and infection groups was concomitant with an increase of seminal MDA levels, but also with MDA measured in viable spermatozoa, which represents the novelty of this study. We identified the IL-6 threshold, beyond which sperm MDA concentration rises concomitantly with the increase of IL-6 concentration. Other studies are needed, considering the increasing number of patients with different pathologies affecting male infertility.

NLRP3 Inflammasome: A New Pharmacological Target for Reducing Testicular Damage Associated with Varicocele

Many bioactive natural compounds are being increasingly used for therapeutics and nutraceutical applications to counteract male infertility, particularly varicocele. The roles of selenium and Polydeoxyribonucleotide (PDRN) were investigated in an experimental model of varicocele, with particular regard to the role of NLRP3 inflammasome. Male rats underwent sham operation and were daily administered with vehicle, seleno-L-methionine (Se), PDRN, and with the association Se-PDRN. Another group of rats were operated for varicocele. After twenty-eight days, sham and varicocele rats were sacrificed and both testes were weighted and analyzed. All the other rats were challenged for one month with the same compounds. In varicocele animals, lower testosterone levels, testes weight, NLRP3 inflammasome, IL-1β and caspase-1 increased gene expression were demonstrated. TUNEL assay showed an increased number of apoptotic cells. Structural and ultrastructural damage to testes was also shown. PDRN alone significantly improved all considered parameters more than Se. The Se-PDRN association significantly improved all morphological parameters, significantly increased testosterone levels, and reduced NLRP3 inflammasome, caspase-1 and IL-1β expression and TUNEL-positive cell numbers. Our results suggest that NLRP3 inflammasome can be considered an interesting target in varicocele and that Se-PDRN may be a new medical approach in support to surgery.