Inflammasomes in human reproductive diseases

Oxidative Stress and the NLRP3 Inflammasome: Focus on Female Fertility and Reproductive Health

Chronic inflammation is increasingly recognized as a critical factor in female reproductive health; influencing natural conception and the outcomes of assisted reproductive technologies such as in vitro fertilization (IVF). An essential component of innate immunity, the NLR family pyrin domain-containing 3 (NLRP3) inflammasome is one of the major mediators of inflammatory responses, and its activation is closely linked to oxidative stress. This interaction contributes to a decline in oocyte quality, reduced fertilization potential, and impaired embryo development. In the ovarian milieu, oxidative stress and NLRP3 inflammasome activation interact intricately, and their combined effects on oocyte competence and reproductive outcomes are significant. The aims of this review are to examine these molecular mechanisms and to explore therapeutic strategies targeting oxidative stress and NLRP3 inflammasome activity, with the goal of enhancing female fertility and improving clinical outcomes in reproductive health.

The role of inflammasome dysregulation in obstructive and non-obstructive azoospermia: a comparative molecular analysis of blood, tissue, and seminal plasma

Background

To address knowledge gaps, this study aimed to investigate the involvement of inflammasomes in the etiology of azoospermia. This study focused on the gene expression of key inflammasome components, including NLR family pyrin domain containing 3 (NLRP-3), CASPASE-1, Interleukin-1β (IL-1β), Interleukin-18 (IL-18), NLR family CARD domain-containing protein 4/ice protease-activating factor (NLRC-4/IPAF), and Absent in melanoma 2 (AIM-2).

Methods

We analyzed gene expression in blood and testicular tissue from patients with obstructive azoospermia (OA) and non-obstructive azoospermia (NOA). Additionally, we compared IL-1β and IL-18 expression levels in seminal plasma samples using the Enzyme-Linked Immunosorbent Assay (ELISA) method. For comparison, blood samples from normospermic (NS) individuals were also genetically evaluated.

Results

Our results indicated significantly higher gene expression of inflammasome components in NOA patients than those in OA patients either in blood or in testicular tissue. Both azoospermic groups exhibited higher mRNA levels of inflammasome genes comparing with those from blood samples of NS men. Seminal plasma samples showed significantly increased levels of IL-1β and IL-18 in NOA patients compared to men with OA. The ROC curve analysis indicated strong and significant predictive power of IL-18, AIM-2 and NLRC-4/IPAF gene expression profiles between NOA vs. NS patients and NOA vs. OA.

Conclusions

Our findings highlight the role of hidden chronic inflammation in azoospermia, particularly within the NOA group. This study provides a foundation for further detailed research, which could aid in the development of diagnostic panels to differentiate between various azoospermic groups.

Nicotinamide mononucleotide improves the ovarian reserve of POI by inhibiting NLRP3-mediated pyroptosis of ovarian granulosa cells

BACKGROUND

Premature ovarian insufficiency (POI) is a common clinical problem, but there is currently no effective treatment. NLRP3 inflammasome-induced pyroptosis is thought to be a possible mechanism of POI. Nicotinamide mononucleotide (NMN) has a certain anti-inflammatory effect, providing a promising approach for the treatment of POI.

METHODS

Thirty female Sprague Dawley rats were randomly divided into a control group (n = 10) and a POI group (n = 20). Cyclophosphamide (CTX) was administered for 2 weeks to induce POI. Then the POI group was divided into two groups: the CTX-POI group (n = 10), which was given saline; and the CTX-POI + NMN group (n = 10), which was given NMN at a dose of 500 mg/kg/day for 21 consecutive days. At the end of the study, the serum hormone concentrations of each group were determined, and each group was subjected to biochemical, histopathological, and immunohistochemical analyses. In the in vitro experiment, cell pyroptosis was simulated by using lipopolysaccharide (LPS) and nigricin (Nig), and then KGN cells were treated with NMN, MCC950, and AGK2, and the levels of Nicotinamide adenine dinucleotide (NAD+) and inflammatory factors Interleukin-18(IL-18) and Interleukin-1β(IL-1β) in the cell supernatants were detected, and the levels of pyroptosis-related factors in the cells were determined.

RESULTS

In POI rats, NMN treatments can improve blood hormone levels and partially improve the number of follicles, enhance ovarian reserve function and ovarian index.The evidence is that the increase in NAD+ levels and the activation of SIRT2 expression can reduce the expression of NLRP3, Gasdermin D (GSDMD), Caspase-1, IL-18, and IL-1β in the ovary.

CONCLUSION

NMN improves CTX-induced POI by inhibiting NLRP3-mediated pyroptosis, providing a new therapeutic strategy and drug target for clinical POI patients.

Blocking GATA6 Alleviates Pyroptosis and Inhibits Abdominal Wall Endometriosis Lesion Growth Through Inactivating the PI3K/AKT Pathway

Endometriosis is a benign gynecological disorder characterized by the abnormal presence of endometrium-like cells, referred to as ectopic tissue, located outside the uterine cavity. Beyond the abnormal proliferation of endometrium-like tissues within and beyond the pelvic cavity, compelling scientific evidence underscores the crucial involvement of the NOD-like receptor NLRP3 inflammasome and pyroptosis in the pathogenesis of EMS. Our investigation has revealed a striking upregulation of the endogenous protein GATA-binding protein 6 (GATA6) in abdominal wall EMS. Notably, the knockdown of GATA6 significantly impaired the viability and migratory potential of primary ectopic endometrial stromal cells (EESCs) while also inhibiting crucial markers of pyroptosis, such as NLRP3, the gasdermin D N-terminal fragment (GSDMD-N), and reactive oxygen species (ROS) levels within these cells. Delving deeper into the underlying mechanisms, we discovered that suppressing GATA6 mitigated the activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway in EESCs. The administration of 740 Y-P, an agonist of the PI3K/AKT pathway, mitigated the inhibitive actions of GATA6 knockdown on EESCs' growth, migration, and pyroptosis, highlighting the intricate crosstalk between GATA6 and this intricate signaling cascade. In vivo experiments corroborated these findings, demonstrating that reduced GATA6 expression effectively restrained the growth of endometrial lesions and concurrently suppressed pyroptosis, accompanied by a dampening of PI3K/AKT signaling within these lesions. In summary, our study underscores the pivotal role of GATA6 in modulating the growth and pyroptosis of abdominal wall EMS through its regulation of the PI3K/AKT signaling pathway. Silencing GATA6 emerges as a promising approach to alleviate pyroptosis and potentially offers a novel therapeutic angle for managing abdominal wall EMS.

Inducers and Inhibitors of Pyroptotic Death of Granulosa Cells in Models of Premature Ovarian Insufficiency and Polycystic Ovary Syndrome

Granulosa cells (GCs), the largest cell population and primary source of steroid hormones in the ovary, are the important somatic ovarian components. They have critical roles in folliculogenesis by supporting oocyte, facilitating its growth, and providing a microenvironment suitable for follicular development and oocyte maturation, thus having essential functions in maintaining female fertility and in reproductive health in general. Pyroptotic death of GCs and associated inflammation have been implicated in the pathogenesis of several reproductive disorders in females including Premature Ovarian Insufficiency (POI) and Polycystic Ovary Syndrome (PCOS). Here, I reviewed factors, either intrinsic or extrinsic, that induce or inhibit pyroptosis in GCs in various models of these disorders, both in vitro and in vivo, and also covered associated molecular mechanisms. Most of these studied factors influence NLRP3 inflammasome- and GSDMD (Gasdermin D)-mediated pyroptosis in GCs, compared to other inflammasomes and gasdermins (GSDMs). I conclude that a more complete mechanistic understanding of these factors in terms of GC pyroptosis is required to be able to develop novel strategies targeting inflammatory cell death in the ovary.

NLRP3 Inflammasome in the Pathogenesis of Miscarriages

Despite significant advances in prenatal medicine, spontaneous miscarriage remains one of the most common and serious pregnancy complications, affecting an increasing number of women. Since many aspects of the pathogenesis of spontaneous miscarriage remain unexplained, the aim of this study has been to assess the involvement of the NLRP3 inflammasome as a potential causative factor. The concentrations of NLRP3, IL-1β, IL-18, and cytochrome C in the serum of patients after miscarriage were measured by means of the immunoenzymatic method. In the placental tissue, the expression of NLRP3, IL-1β, IL-18, and Caspase-1 as well as that of the classical apoptosis biomarkers Fas, FasL, Bcl-2, and Ca was evaluated by means of immunohistochemistry techniques. Additionally, in whole blood, the concentrations of elements crucial for pregnancy progression, such as Ca, K, Mg, and Na, were examined by means of the ICP-OES method. Significantly higher concentrations of NLRP3 and IL-18 were demonstrated in the serum of patients with miscarriage as compared to the control group. In the placental tissue samples, a higher expression of IL-1β, IL-18, and Caspase-1 proteins was noted in women who had experienced miscarriage as compared to the control group. At the same time, a significantly lower expression of FasL and Bcl-2 proteins as well as Ca deposits was observed in women after miscarriage as compared to those with a normal pregnancy outcome. Significantly lower concentrations of Ca and K were recorded in the blood of patients with spontaneous miscarriage as compared to pregnant women. The analysis of the results x indicated a greater involvement of the inflammasome in women with spontaneous miscarriage associated with oxidative-antioxidative imbalance than in the case of miscarriage related to NET formation. Our research has provided evidence for the involvement of the inflammasome in the process of spontaneous miscarriage and identifies a new direction for diagnostics that includes NLRP3 as a preventive element in prenatal care, particularly in light of the steadily declining number of pregnancies and the increasing number of reproductive failures.

Unveiling the role of chronic inflammation in ovarian aging: insights into mechanisms and clinical implications

Ovarian aging, a natural process in women and various other female mammals as they age, is characterized by a decline in ovarian function and fertility due to a reduction in oocyte reserve and quality. This phenomenon is believed to result from a combination of genetic, hormonal, and environmental factors. While these factors collectively contribute to the shaping of ovarian aging, the substantial impact and intricate interplay of chronic inflammation in this process have been somewhat overlooked in discussions. Chronic inflammation, a prolonged and sustained inflammatory response persisting over an extended period, can exert detrimental effects on tissues and organs. This review delves into the novel hallmark of aging-chronic inflammation-to further emphasize the primary characteristics of ovarian aging. It endeavors to explore not only the clinical symptoms but also the underlying mechanisms associated with this complex process. By shining a spotlight on chronic inflammation, the aim is to broaden our understanding of the multifaceted aspects of ovarian aging and its potential clinical implications.

α-Ketoglutarate Improves Ovarian Reserve Function in Primary Ovarian Insufficiency by Inhibiting NLRP3-Mediated Pyroptosis of Granulosa Cells

SCOPE

Premature ovarian insufficiency (POI) is a common female infertility problem, with its pathogenesis remains unknown. The NOD-like receptor family pyrin domain-containing 3 (NLRP3)-mediated pyroptosis has been proposed as a possible mechanism in POI. This study investigates the therapeutic effect of α-ketoglutarate (AKG) on ovarian reserve function in POI rats and further explores the potential molecular mechanisms.

METHODS AND RESULTS

POI rats are caused by administration of cyclophosphamide (CTX) to determine whether AKG has a protective effect. AKG treatment increases the ovarian index, maintains both serum hormone levels and follicle number, and improves the ovarian reserve function in POI rats, as evidence by increased the level of lactate and the expression of rate-limiting enzymes of glycolysis in the ovaries, additionally reduced the expression of NLRP3, Gasdermin D (GSDMD), Caspase-1, Interleukin-18 (IL-18), and Interleukin-1 beta (IL-1β). In vitro, KGN cells are treated with LPS and nigericin to mimic pyroptosis, then treated with AKG and MCC950. AKG inhibits inflammatory and pyroptosis factors such as NLRP3, restores the glycolysis process in vitro, meanwhile inhibition of NLRP3 has the same effect.

CONCLUSION

AKG ameliorates CTX-induced POI by inhibiting NLRP3-mediated pyroptosis, which provides a new therapeutic strategy and drug target for clinical POI patients.