Role of pyroptosis in pregnancy-related diseases

Pyroptosis in pregnancy physiology

Under normal physiological conditions, pyroptosis serves a crucial role in protecting the host defense against pathogen infections, such as implantation, placentation and immune response regulation (Yu & Li, 2021). Pyroptosis, as a kind of regulated cell death, and its role in pregnancy still controversial. Pyroptosis was found at the maternal-fetal interface in epithelial cells at the implantation site (Li et al., 2024). Pyroptosis could be observed in mouse uterus on day 4 pregnant, and the levels of the proteins NLRP3, apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), cleaved caspase 1, and GSDMD-N increased on day 4 of pregnancy compared with pseudopregnancy group, which suggested caspase1-dependent classical pathway was the main pathway in the beginning of pregnancy (Li et al., 2024).

Pyroptosis in PE

PE is a complex multisystem disorder defined by sudden onset of hypertension after 20 weeks of gestation, accompanied by at least one additional complication, including proteinuria, placental dysfunction or maternal organ dysfunction (Dimitriadis et al., 2023). The incidence rate range of PE is about 3–5%, usually begins after 20 weeks of pregnancy and late onset if more frequent than early onset (Fox et al., 2019). Pyroptosis markers are upregulated in PE with inflammatory state. Accumulating evidence indicates upregulated expression of NLRP3 inflammasome components in peripheral blood cells and placental tissues from women with PE compared to normotensive healthy pregnant controls (Shirasuna, Karasawa & Takahashi, 2020). By immunohistochemistry and quantified by reverse transcription-qPCR (RT-qPCR) analysis, pregnant women with PE have higher levels of NLRP3 inflammasome in placenta tissue than healthy pregnant women (Weel et al., 2017). The results of human tissue and in vivo experiments have also shown that extracellular vesicles activate maternal platelets and NLRP3 inflammasomes in trophoblasts, which inducing placental aseptic inflammation and PE (Dimitriadis et al., 2023). Inhibiting this pathway can alleviate PE symptoms (Kohli et al., 2016). In vitro study shown that human trophoblast cells treated with serum from patients with PE could induce NLRP3 inflammasome activation and cell pyroptosis, releasing the inflammatory factors IL-1β and IL-18 in cell models mimicking pathophysiological conditions (Cheng et al., 2019). Results have shown that the gene expression of NLRP1, NLRP3, caspase-1, IL-1β, and tumor necrosis factor α (TNF-α) in monocytes from the PE group was elevated compared with that in the control group (Matias et al., 2015).

Numerous studies consistently report elevated NLRP3 inflammasome activation in women with PE. For example, monocytes from PE patients exhibit significantly higher basal expression of NLRP3, caspase-1, IL-1β, and TNF-α compared to normotensive pregnant controls (Matias et al., 2015). Similarly, placental tissues from PE patients show increased NLRP3, ASC, and caspase-1 expression in syncytiotrophoblasts and trophoblasts, with co-localization of NLRP3 and complement factors like C5a and terminal complement complex (TCC) (Stødle et al., 2018). While exact prevalence varies by tissue type and study design, NLRP3 upregulation is observed in PE cases across placental, peripheral blood, and monocytes and endothelial cell samples (Socha et al., 2020). PE is pathologically characterized by excessive oxidative stress, systemic inflammation, endothelial dysfunction, and fetal complications (Shirasuna et al., 2015; Nunes, Mattioli & Sandrim, 2021). The pathological process may be triggered by the activation of NLRP3 inflammasome mediated by reactive oxygen species (ROS), which triggers the release of pro-inflammatory cytokines, including IL-1β and IL-18 (Nunes, Mattioli & Sandrim, 2021). These cytokines amplify the inflammatory cascade and exacerbate oxidative stress within the endothelium. As a key regulator of immune function, nitric oxide modulates inflammatory signaling pathways and maintains vascular homeostasis (Guerby et al., 2021). This sustained pro-inflammatory state exacerbates endothelial dysfunction, indicating that endothelial inflammation may be a key driving factor in the occurrence and progression of PE (Phipps et al., 2019).

The implication of pyroptosis-related inflammasomes in the pathophysiology of PE has also been recognized through in vivo experiments. Mechanistically, the inflammatory signal pathways and main inflammasomes have been shown to be associated with pyroptosis in PE (Banerjee et al., 2021). NLRP3 could induce pyroptosis through the toll-like receptor (TLR4)/NF-κB/PFKFB3 signaling pathway in preeclamptic trophoblast models (Zhang et al., 2021). The use of drugs that can inhibit NLRP3 may be a good choice for the future treatment of PE (Nunes, Mattioli & Sandrim, 2021). GSDMD, the important executor of pyroptosis, and caspase-1 were found upregulated expression in the placenta tissue of women with early onset PE (Cheng et al., 2019). It has been reported that IL-11 could activate pyroptosis associated with NLRP3, causing PE in human first trimester placental villi (Menkhorst et al., 2023). Gross pathology in the preeclamptic placenta has revealed vascular sclerosis and multiple placental infarctions (Ezeigwe et al., 2018). The insufficient local oxygen supply nutrients can induce trophoblast cell death, which leads to endothelial activation and release of inflammatory mediators, including damage-associated molecular patterns (DAMPs), such as cell-free fetal DNA, uric acid, IL-1α, and high mobility group box 1 (HMGB1) (Nadeau-Vallée et al., 2016). DAMPs, as endogenous danger molecules, activate the innate immune system and release proinflammatory cytokines, which cause the damage of endothelial cells and dysfunction of trophoblast cells, and then lead to PE (McCarthy & Kenny, 2016). Another study showed that AIM2, as a cytosolic DNA sensor, could be activated by free fetal DNA and lead to the development of PE (Li et al., 2020). Silencing NEAT1 could promote Treg/TH17 immune cell balance and downregulate the microRNA (miR)-458-5p/AIM2 axis in PE (Chen et al., 2021).

Moreover, early-onset and late-onset PE exhibit distinct pathophysiological mechanisms, while syncytiotrophoblaset shown increasing number of pyroptotic markers in late-onset PE (Redman, Staff & Roberts, 2022). The downregulation of histone deacetylase 2 in women with PE was accompanied by an increase of FOXO3 and PERK, along with an increase in the expression of IL-1 β and IL-18, inhibiting cell proliferation, migration, and invasion, ultimately leading to pyroptosis in trophoblasts (Liu & Yang, 2023). Liu et al. (2020) reported that caspase-1 may increase pyroptosis by angiotensin II type 1 receptor exposure in women with PE. Lipoxin A4 could inhibit AT1-AA in PE by regulating caspase-1 expression (Liu et al., 2020). TDRKH-AS1 in small extracellular vesicles, isolated from oxidative stress trophoblasts, may be involved in the pathogenesis of PE by inducing pyroptosis and exacerbating endothelial dysfunction (Chen et al., 2023). Therefore, the activation of inflammasomes may participate in the pathogenesis of PE by raising inflammation (Table 1).

While no clinical trials explicitly target pyroptosis in PE, several ongoing studies investigate related pathways. A small molecule inhibitor, MCC950, as a selective NLRP3 antagonist, reduces maternal hypertension, oxidative stress, and fetal reabsorption in the reduced uterine perfusion pressure (RUPP) rat model (Wang et al., 2023). Aspirin, anti-inflammatory agents, commonly used for PE prophylaxis, indirectly modulates NLRP3 by reducing thromboxane synthesis and oxidative stress (Lin et al., 2022).

Pyroptosis and RSA

RSA usually refers to the occurrence of three or more consecutive fetal losses before 28 weeks of pregnancy (Deng, Liao & Zhu, 2022). The etiology of RSA is complex and not clear, and the immune inflammatory imbalance between mother and fetus is one of the possible mechanisms of RSA. NLRP3-induced abnormal inflammatory response on the maternal-fetal interface of women with RSA, leads to unsuccessful embryo implantation (Gao et al., 2020). Zhu et al. (2021) reported pyroptosis in the decidual tissue of women with RSA patients and in a mouse model. It was shown that the expression of HMGB1, TLR2, TLR4, receptor for advanced glycation end-products (RAGE), NLRP3, caspase-1, GSDMD, and NF-κB was increased in the maternal-fetal interface tissue (Zhu et al., 2021). After treatment with aspirin, the expression of HMGB1, RAGE, TLR2, TLR4, and NLRP3 inflammasome components was decreased, confirming the possible involvement of the NLRP3 inflammasome in RSA and providing evidence for the application of aspirin in RSA (Zhu et al., 2021). MITA-triggered pyroptosis in the maternal-fetal interface, which interrupted the balance of immune microenvironment and caused abortion during pregnant (Liu et al., 2023).

Emerging evidence implicates NLRP3 inflammasome-mediated pyroptosis as a critical driver of RSA pathogenesis. The canonical NLRP3 inflammasome pathway has been implicated in RSA. Triggered by DAMPs like urate crystals, NLRP3 activation recruits ASC and activates caspase-1, which leads to GSDMD cleavage, pore formation, and release of pro-inflammatory cytokines such as IL-1β and IL-18, disrupting the maternal-fetal interface (Shi et al., 2015). NLRP3 activation contributes to implantation failure by inducing excessive inflammation. Study shown that in pregnancy failure models, NLRP3 activation increases IL-1β release, which reduces embryo survival. In RSA, this may impair trophoblast invasion and increase macrophage activity, hindering successful implantation (Gao et al., 2020). Molecularly, RSA is associated with upregulated NLRP3, ASC, and caspase-1 in placental tissues, along with altered GSDMD cleavage. Maternal circulation also shows elevated IL-1β and IL-18, disrupting placental vascular remodeling and nutrient supply (D’Ippolito et al., 2016). In recent research, pyroptosis was found essential in the microenvironment of the chorionic villus tissue of women with RSA (Wang et al., 2024). A total of 16 genes were found associated with pyroptosis in the GSE22490 and GSE76862 placental datasets (Wang et al., 2024). It was also found that BTK, TLR8, NLRC4, and TNFSF13B were closely related to immune cells in the RSA placenta tissue (Wang et al., 2024). Exposure to BPDE stimulates the Inc-HZ14/ZBP1/NLRP3 axis, which in turn causes miscarriage and trophoblast cell pyroptosis (Wang et al., 2023). One of the pathogenesis in RSA was facilitated by the activated NLRP3 inflammasome by regulated Th17 and T cell imbalance (Lu et al., 2019). Novel treatment therapy for targeting NLRP3 may help reduce miscarriage rates and improve neonatal prognosis (Zhou, Li & Zhang, 2020; Zhao et al., 2024). So far, a number of promising inflammasome complex activation inhibitors have been described such as MCC950 and beta hydroxybutyrate, which can affect NALP3 expression (Di Nicuolo et al., 2018).

Pyroptosis and fetal growth restriction

Fetal growth rate (FGR) is a condition that affects 5–10% of pregnancies and is a leading cause of fetal mortality (Nardozza et al., 2017). There is high expression of pyroptosis-related factors such as NLRP7, IL-1β, ASC, and cleaved caspase-1 in the placenta of pregnant women with FGR (Abi Nahed et al., 2019). The exposure of prenatal IL-1 has shown adverse reactions and effects on the development during the perinatal period in mice (Nadeau-Vallée et al., 2017). The maternal serum GSDMD concentration and its mediated placental pyroptosis were found higher in pregnant women who were complicated by intrauterine growth restriction (Kobal et al., 2023). Diabetic pregnant mice had increased expression of chemerin, which could induce the activation of pyroptosis and a cognitive disorder in the brain of the fetal mice (Liang et al., 2019). By contrast, docosahexaenoic acid could improve cognitive impairment by attenuating hippocampal pyroptosis in rats with intrauterine growth restriction (Wan et al., 2023).

Pyroptosis and bronchopulmonary dysplasia

Among those premature infants, bronchopulmonary dysplasia (BPD) is a familiar clinical abnormality in preterm infants. In the BPD mouse model, nuclear factor e2-related factor 2 (Nrf2) may lead to the activation of the NLRP3 inflammasome, which acts as one of the molecular mechanisms of pyroptosis in BPD pathogenesis (Wang et al., 2023). Nrf2 deficiency increased pyroptosis and BPD in Nrf2^-/-mice with intrauterine growth restriction by interrupting GSDMD transcription (Chen et al., 2024). Rapamycin reduced LPS-induced pyroptosis in neonatal rats with BPD by inhibiting mTOR phosphorylation and inducing autophagy (Zhang et al., 2023). Infants with BPD often suffer from lung and brain damage, leading to long-term neurodevelopmental disorders. A study involving C57/BL6 mouse pups revealed high oxygen-activated NLRP1 inflammasome and increased the expression of IL-1β and GSDMD, which are key inflammasomes involved in lung and brain tissue pyroptosis (Dapaah-Siakwan et al., 2019).

The NLRP3 inflammasome, triggers caspase-1-mediated pyroptosis, leading to the release of pro-inflammatory cytokines (IL-1β and IL-18) and decreased alveolarization (Liao et al., 2015). Excessive release of proinflammatory cytokines, particularly IL-1β, from alveolar macrophages is believed to play a key role in impairing alveolar development in BPD patients (Ryan, Ahmed & Lakshminrusimha, 2008). Interestingly, research found caffeine could significantly reduce NLRP3 expression in LSP-1induced THP-1 macrophage by suppressing MAPK/NF-κB signaling and A2aR-mediated ROS production (Zhao et al., 2019). In both rats models and alveolar epithelial cell line study, nesfatin-1 reduced neutrophils accumulation and inhibited inflammatory response by modulating HMGB-1/TLR4/p65/NLRP3 signal pathway in BPD (Yang, Luo & Lou, 2025). Hydrogen has been shown to alleviate cellular injury by suppressing the inflammatory response and oxidative stress, which is mediated through the Nrf2-dependent regulation of NLRP3 and NF-κB signaling pathways (Hu, Wang & Han, 2022). A holistic understanding of pyroptosis in BPD as shown in Fig. 3.

Pyroptosis with preterm birth

Preterm birth refers to the birth of a baby before 37 weeks of pregnancy, the rate range of preterm birth is 4–16% (Vogel et al., 2018), which is the main cause of neonatal mortality (Perin et al., 2022). There are multiple causes of preterm birth. Most preterm births occur spontaneously, but there are also some caused by pathological factors such as infections or other pregnancy-related complications. Among them, the inflammatory response at the maternal-fetal interface is a key factor in the occurrence of preterm birth (Humberg et al., 2020). Gotsch et al. (2008) first discovered the relationship between cell pyroptosis and the initiation of labor in 2008. There is sufficient evidence that inflammasomes, specifically NLRP3, play a vital role in preterm birth (Motomura et al., 2022; Galaz et al., 2023). In a study, incubation of chorioamniotic membranes with HMGB1 (mimicking preterm birth) increased mature IL-1β, IL-6, and mRNA levels of proinflammatory mediators (NFKB1, IL6, TNF, etc.), HMGB1 receptors (RAGE, TLR2), inflammasome components (NLRP3, AIM2), cleaved caspase-1, and MMP-9 (Plazyo et al., 2016). Inflammation in the amniotic fluid is one of the key factors in preterm birth, including both sterile and non-sterile inflammatory responses (Gomez-Lopez et al., 2019). Women delivering pre-term with intra-amniotic infection had increased levels of GSDMD, caspase-1 and IL-1β than those women delivering full-term (Gomez-Lopez et al., 2019). Gotsch et al. (2008) also showed that the level of caspase-1 in the amniotic fluid of spontaneously preterm pregnant women with combined intrauterine infection was markedly higher than that for spontaneously preterm birth in women without combined infection. In the placental tissues of human spontaneous preterm labor with acute histological chorioamnionitis, upregulation of NLRP3, caspase-4, IL-1β and IL-18 expression were observed, which indicating the activation of pyroptosis pathways in preterm labor (Gomez-Lopez et al., 2017). Zhu et al. (2021) also showed elevated NLRP1, NLRP3, AIM2, and NLRC4 inflammasome activation in the placenta tissue of women with premature rupture of membranes. Besides, women with sterile intra-amniotic inflammation had a lower level of GSDMD in their amniotic fluid than those women with intra-amniotic infection, and its expression in the chorioamniotic membranes was related to IL-1β and caspase-1 (Gomez-Lopez et al., 2019). Consequently, both the canonical and noncanonical pathways of pyroptosis are involved in the occurrence of preterm birth.

Inhibition of inflammasome activation may be a new direction for future research on preterm birth prevention and treatment. In an animal model of LPS-induced intra-amniotic inflammation, the NLRP3 inflammasome in the fetal membranes and decidua of the preterm birth group was notably increased compared with the control group (Faro et al., 2019) . After further treatment with the NLRP3 inhibitor MCC950, the birth rate was decreased in the preterm birth group, which improved the fetal outcome in an in vivo study (Faro et al., 2019). Lee et al. (2021) also provided evidence for the role of LPS-induced NLRP3 inflammasome in placental inflammation, indicating that targeting TBK1 attenuates LPS-induced NLRP3 inflammasome activation by regulating the mTORC1 pathways in trophoblast cells. The authors indicated that the rate of preterm birth induced by trophoblast inflammation could be decreased by omega-3 fatty acids (Chen et al., 2018). The aforementioned results provide new insights for the mechanism of premature birth, which offering possibilities for the development of drugs targeting pyroptosis and inflammasome to prevent premature birth in the future (Fig. 4).

Pyroptosis and GDM

GDM is one of the most common complications of pregnancy-related metabolic diseases during pregnancy, which not only increases the risk of PE, type 2 diabetes and others, but also has an adverse impact on embryonic intrauterine development and newborn health (Ye et al., 2022). Insulin resistance underlies the pathogenesis of GDM by impairing glucose homeostasis and leading to elevated blood glucose levels. Compared with healthy pregnant women, obese pregnant women or women with GDM tend to have more severe insulin resistance (Pantham, Aye & Powell, 2015). Changes in insulin sensitivity are a normal physiological state during pregnancy, which can lead to the pregnancy-induced insulin resistance (Liu et al., 2020). In maternal adipose tissue, increased protein expression of caspase-1 and IL-1β could be used as evidence of insulin resistance in women with GDM (Lappas, 2014). During pregnancy, inflammasomes are activated to produce proinflammatory cytokines such as IL-1β and IL-18, which lead to pyroptosis and insulin resistance (Gayatri et al., 2024). Han et al. (2024) proposed that the serum concentration of NLRP3 and the expression of its effector molecules, caspase-1, IL-1β, and IL-18, mid pregnancy can serve as biomarkers for predicting adverse pregnancy outcomes. Deficiency of hydrogen sulfide synthase in the placenta of women with GDM may lead to excessive activation of the NLRP3 inflammasome (Wu et al., 2022). Pyroptosis-associated inflammasomes have not only been found in the serum level of women with GDM, but also in the adipose tissue. Based on the evidence to date, TNFα, adipocyte fatty acid-binding protein, leptin, and adiponectin seem to be the closest adipokines related to the pathophysiology of GDM (Fasshauer, Blüher & Stumvoll, 2014). Through miRNA analysis of pregnant women’s plasma, it was found that 13 miRNAs were upregulated when NLRP3 increased, among which miR-106-5p and miR-210-3p were significantly increased in GDM (Monti et al., 2023). As a critical step in pyroptosis, the NLRP3 inflammasome, encompassing the priming signal model and activation signal model, plays a pivotal role in the occurrence, development and complication development of diabetes (Yu et al., 2020).

The correlation between pyroptosis and insulin resistance has been extensively reported (Lin et al., 2020; Wei & Cui, 2022). Inflammatory environment disorders of the placenta and maternal adipose tissue are the main factors of insulin resistance in GDM (Olmos-Ortiz et al., 2021). Han et al. (2024) described the elevated expression of pyroptosis factors in the serum of women with GDM compared with healthy pregnant women. Compared with the control group, the serum levels of caspase-1, IL-1β, IL-18, and NLRP3 in the GDM group were significantly increased (Han et al., 2024). In trophoblast, TP53-induced glycolysis and apoptosis regulator deficiency could induce inflammation and pyroptosis by activating the NLRP3-ASC-caspase1 signaling pathway (Guo et al., 2023). In contrast, targeting the expression of inflammasomes with anti-inflammatory drugs could effectively reduce the inflammation response in GDM (Fig. 5). Treatment with procyanidins could alleviate insulin resistance by reducing the activation of inflammatory via the NF-κB/NLRP3 signal pathway in a GDM mouse model (Liu et al., 2022). An increased expression of SPOCD1 in villi mesenchymal stem cells could attenuate glucose-induced pyroptosis through β-catenin in human umbilical cells, proposing a new therapeutic avenue for GDM treatment in the future (Wang et al., 2023).

Pyroptosis in other pregnancy related diseases

Pyroptosis occurs in the maternal or fetal body caused by some biological factors such as infection, viral or parasitic inflammation. Congenital cytomegalovirus infection could trigger neurodevelopmental disorders, such as brain calcification and neuroinflammation, which pathological analysis shown cell pyroptosis (Zhou et al., 2022). Zika virus could induce adverse fetal outcomes by activating pyroptosis of placenta cells (Zhao et al., 2022). Immunohistochemical analysis showed increased expression of NLRP1, NLRP2, NLRP3, AIM2, IL-1 IL-1β, IL-18, and IL-33, and caspase 1 in Zika virus-positive stillborn brain tissue compared with controls (de Sousa et al., 2018). Inflammasomes are activated by Zika virus infection, leading to the activation of NLRP3-dependent pyroptosis (Wen et al., 2022). In addition, Monti et al. (2023) reported that SARS-CoV-2 infection could also increase the NLRP3-mediated pyroptosis in pregnant women which can induce adverse pregnancy outcomes. Nascimento & Alves-Filho (2023) described the key role of gut microbiota disorder during pregnancy in triggering excessive macrophage pyroptosis, which has raised concerns to the pathogenesis of sepsis. Quan et al. (2023) reported that Toxoplasma gondii infection induced ROS production and CatB activation in placental cells, which could trigger NLRP1/NLRP3/NLRC4/AIM2 inflammasome dependent caspase-1-mediated pyroptosis.

Subclinical hypothyroidism is one of the common diagnoses during pregnancy, as its prevalence in pregnant women is approximately 3.5% (Dong et al., 2020). The Chinese herb Bushen Antai could reduce inflammatory factors expression and improve TSH concentration by inactivating pyroptosis in a subclinical hypothyroidism rats study (He et al., 2022). In animal study, maternal hypothyroidism could activate pyroptosis by increasing GSDMD, NLRP3, and IL-1β at the maternal-fetal interface of rats (Santos et al., 2023). Smoking during pregnancy increases the risk of congenital fetal malformations. As report, in animal experiments, pregnant women exposure to cigarette smoke exacerbated congenital clubfoot in fetal mice (Lou et al., 2021).