Pyroptosis Signaling Pathways Research Articles

Kui Jie Tong Ameliorates Ulcerative Colitis by Regulating Gut Microbiota and NLRP3/Caspase-1 Classical Pyroptosis Signaling Pathway.

Ulcerative colitis (UC) is one of the most refractory digestive diseases in the world. Kui jie tong (KJT) is an effective traditional Chinese medicine used clinically to treat UC. This study observed the regulatory effects of KJT on NIMA-related kinase 7- (NEK7-) activated nod-like receptor protein-3 (NLRP3)/caspase-1 classical pyroptosis pathway and intestinal flora in UC model rats. KJT components were analyzed using an ultraperformance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS). A UC Sprague Dawley (SD) rat model was established using sodium dextran sulfate (DSS). Rats were randomly divided into four groups: control group (CG), UC model group (UG), KJT group (KG), and sulfasalazine (SASP) group (SG). After seven days of intervention, each group's body weight, disease activity index (DAI) scores, and colon length were recorded. Intestinal mucosal injury to each group was observed using hematoxylin-eosin staining. Additionally, we investigated the expression levels of NEK7, NLRP3, ASC, caspase-1, and GSDMD in intestinal mucosa, as well as serum interleukin- (IL-) 1β, IL-18, and IL-33 proinflammatory factors. Intestinal microflora was analyzed using 16s rRNA sequencing. KJT controlled weight loss; decreased DAI scores; restored colon length; improved pathological injury in the colon; inhibited NEK7, NLRP3, ASC, caspase-1, cleaved-caspase-1, GSDMD, and GSDMD-N expression; and decreased IL-1β, IL-18, and IL-33 contents in UG rats' serum and colon tissue (P <0.001 or P <0.05). KJT also increased Ruminococcaceae, unclassified_f_Ruminococcaceae, and unclassified_g_Ruminococcus_1 levels and decreased Erysipelotrichia, Erysipelotrichales, Erysipelotrichaceae, Turicibacter, and uncultured_bacterium_g_Turicibacter levels. KJT alleviated UC immune-inflammatory responses to NLRP3/caspase-1 by inhibiting the NEK-7-activated classic pyroptosis pathway and improving intestinal microflora.

Cold Stress Induced Liver Injury of Mice through Activated NLRP3/Caspase-1/GSDMD Pyroptosis Signaling Pathway.

The body needs to generate heat to ensure basic life activities when exposed to cold temperatures. The liver, as the largest glycogen storage organ in the body and main heat-producing organ at rest, may play a role in chronic cold exposure. Recent studies suggested that pyroptosis plays a crucial role in liver diseases. However, the role of pyroptosis in cold stress-induced liver injury is not clear. Hence, in this study, we attempted to investigate the effects of chronic cold exposure on liver function, apoptosis, oxidative stress and inflammation in mice by establishing a mouse model of chronic cold exposure, and to investigate whether pyroptosis pathways are involved in the process of chronic cold exposure. In vivo, our results show that inflammatory cell infiltration and other pathological changes in liver cells and the activity of liver enzyme evidently increased in the serum and liver of cold-exposed mice, suggesting cold stress may result in liver injury. Remarkably, increased expression of heat shock protein 70 (HSP70) and HSP90 proteins proved the cold stress model is successfully constructed. Then, elevated levels of apoptosis, inflammation, oxidative stress and pyroptosis related proteins and mRNAs, such as cysteinyl aspartate specific proteinase-3 (Caspase-3), inducible nitric oxide synthase (iNOS), nuclear factor erythroid2-related factor 2 (Nrf2) and gasdermins D (GSDMD), confirmed that cold exposure activated apoptosis, oxidative stress and pyroptosis, and released inflammation cytokines. Meanwhile, in vitro, we got similar results as in vivo. Further, adding an NLR family pyrin domain containing 3 (NLRP3) inhibitors found that suppression expression of NLRP3 results in the essential proteins of pyroptosis and antioxidant evidently reduced, and adding GSDMD inhibitor found that suppression expression of GSDMD accompanies with the level of Nrf2 and heme oxygenase-1 (HO-1) obviously reduced. In summary, these findings provide a new understanding of the underlying mechanisms of the cold stress response, which can inform the development of new strategies to combat the effects of hypothermia.

Emodin Ameliorates Acute Pancreatitis-Associated Lung Injury Through Inhibiting the Alveolar Macrophages Pyroptosis.

Objective: To investigate the protective effect of emodin in acute pancreatitis (AP)-associated lung injury and the underlying mechanisms. Methods: NaT-AP model in rats was constructed using 3.5% sodium taurocholate, and CER+LPS-AP model in mice was constructed using caerulein combined with Lipopolysaccharide. Animals were divided randomly into four groups: sham, AP, Ac-YVAD-CMK (caspase-1 specific inhibitor, AYC), and emodin groups. AP-associated lung injury was assessed with H&E staining, inflammatory cytokine levels, and myeloperoxidase activity. Alveolar macrophages (AMs) pyroptosis was evaluated by flow cytometry. In bronchoalveolar lavage fluid, the levels of lactate dehydrogenase and inflammatory cytokines were measured by enzyme-linked immunosorbent assay. Pyroptosis-related protein expressions were detected by Western Blot. Results: Emodin, similar to the positive control AYC, significantly alleviated pancreas and lung damage in rats and mice. Additionally, emodin mitigated the pyroptotic process of AMs by decreasing the level of inflammatory cytokines and lactate dehydrogenase. More importantly, the protein expressions of NLRP3, ASC, Caspase1 p10, GSDMD, and GSDMD-NT in AMs were significantly downregulated after emodin intervention. Conclusion: Emodin has a therapeutic effect on AP-associated lung injury, which may result from the inhibition of NLRP3/Caspase1/GSDMD-mediated AMs pyroptosis signaling pathways.

Pyrroloquinoline quinone ameliorates renal fibrosis in diabetic nephropathy by inhibiting the pyroptosis pathway in C57BL/6 mice and human kidney 2 cells.

Diabetic nephropathy (DN), which is characterized by renal fibrosis, is a major complication of diabetes, a disease that afflicted more than 460 million people worldwide in 2019. Pyroptosis is an essential signaling pathway in DN-related injuries, such as renal fibrosis. Pyrroloquinoline quinone (PQQ) is a naturally occurring bioactive compound that protects human kidney 2 (HK-2) cells from oxidative stress-induced damage caused by high glucose concentrations. However, the nature and underlying mechanism of the effect of PQQ on DN-related renal fibrosis remains unclear. In this study, we evaluated whether PQQ has potential protective effects against renal fibrosis due to DN by establishing type 1 diabetes in mice via streptozotocin treatment and then inhibiting their pyroptosis signaling pathway. We found that compared to control mice, the area of renal fibrosis and injury were significantly increased in diabetic mice, and this was accompanied by increased levels of expression of collagen Ⅰ and transforming growth factor-β1; increased concentrations of the inflammatory cytokines, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α; and activation of the pyroptosis pathway components nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3), caspase-1, IL-1β, and IL-18. All of these changes were reversed by PQQ treatment. Analogously, we treated cultured HK-2 cells with a high concentration of glucose (35mmol/L), which caused these cells to exhibit significantly increased concentrations of reactive oxygen species (ROS), phosphorylated (p)-nuclear factor kappa B (NF-κB), p-IkappaB, NLRP3, caspase-1, IL-1β, and IL-18, and the loss of mitochondrial transmembrane potential. However, PQQ treatment significantly blunted these effects. In conclusion, in this study we demonstrated that PQQ attenuates renal fibrosis by alleviating mitochondrial dysfunction, reducing ROS production, and inhibiting the activation of the NF-κB/pyroptosis pathway under conditions of DN and hyperglycemia.

Dietary Tryptophan Supplementation Improves Antioxidant Status and Alleviates Inflammation, Endoplasmic Reticulum Stress, Apoptosis, and Pyroptosis in the Intestine of Piglets after Lipopolysaccharide Challenge.

Tryptophan can alleviate stress and improve intestinal health, but the precise mechanism has not been fully elucidated. This study aimed to examine the effects of tryptophan supplementation on antioxidant status, inflammation, endoplasmic reticulum (ER) stress, apoptosis, and pyroptosis signaling pathway in the intestine of piglets after Escherichia coli lipopolysaccharide (LPS) challenge. Thirty-two weaning piglets were allotted to four treatments including: non-challenged control, LPS-challenged control, LPS + 0.2% tryptophan and LPS + 0.4% tryptophan. On day 35 of feeding, piglets were injected intraperitoneally with 100 μg/kg of body weight LPS or saline. Among the LPS-challenged pigs, tryptophan supplementation improved intestinal morphology as indicated by greater villus height, villus area and smaller crypt depth, and antioxidant status, and decreased the mRNA expression and concentration of proinflammatory cytokines. Moreover, tryptophan downregulated the expression of ER stress (ER oxidoreductase-1α, ER oxidoreductase-1β, glucose-regulated protein-78, activating transcription factor 6, C/EBP homologous protein), apoptosis (B-cell lymphoma-2, BCL2-associated X protein, caspase 3), and pyroptosis signaling pathway (nucleotide-binding oligomerization domain-like receptor protein 3, caspase 1, gasdermin-D, apoptosis-associated speck-like protein containing a CARD). Collectively, tryptophan supplementation can contribute to gut health by improving antioxidant status and alleviating inflammation, ER stress, apoptosis, and pyroptosis in the intestine of piglets after lipopolysaccharide challenge.

TI: NLRP3 Inflammasome-Dependent Pyroptosis in CNS Trauma: A Potential Therapeutic Target

Central nervous system (CNS) trauma, including traumatic brain injury (TBI) and traumatic spinal cord injury (SCI), is characterized by high morbidity, disability, and mortality. TBI and SCI have similar pathophysiological mechanisms and are often accompanied by serious inflammatory responses. Pyroptosis, an inflammation-dependent programmed cell death, is becoming a major problem in CNS post-traumatic injury. Notably, the pyrin domain containing 3 (NLRP3) inflammasome is a key protein in the pyroptosis signaling pathway. Therefore, underlying mechanism of the NLRP3 inflammasome in the development of CNS trauma has attracted much attention. In this review, we briefly summarize the molecular mechanisms of NLRP3 inflammasome in pyroptosis signaling pathway, including its prime and activation. Moreover, the dynamic expression pattern, and roles of the NLRP3 inflammasome in CNS post-traumatic injury are summarized. The therapeutic applications of NLRP3 inflammasome activation inhibitors are also discussed.

The inhibiting effect of Aspirin Triggered-Resolvin D1 in non-canonical pyroptosis in rats with acute keratitis

PurposeTo investigate the effect of Aspirin Triggered-Resolvin D1 (AT-RvD1) as an anti-pyroptosis and anti-inflammatory agent on lipopolysaccharide (LPS) induced acute keratitis in Wistar rats. MethodsAcute keratitis in rats were induced by LPS stromal injection. Inflammatory reaction was measured by clinical score and histological observations. The non-canonical pyroptosis, the role of AT-RvD1 and Docosahexaenoic Acid (DHA) on non-canonical pyroptosis, were verified by quantification real-time PCR (qRT-PCR) and Western-blot. Besides, Human corneal epithelial cells (HCECs) primed with LPS, were stimulated with Nigericin, AT-RvD1 and necrosulfonamide (NSA), a Gasdermin-D (GSDMD) inhibitor separately. CCK-8 tests and flow cytometry were conducted to evaluate the cell viability and death ratio. And the marker of non-canonical pyroptosis were verified by Western blot. ResultsAT-RvD1 and DHA both alleviated the inflammation of rat cornea through inhibiting the expression of Caspase-11 and p30 which was triggered by LPS. Meanwhile, the activation of Caspase-4 and p30 were also significantly suppressed by AT-RvD1 in vitro, which is consistent with the results in rats. ConclusionsThe non-canonical pyroptosis signaling pathways played an important role in rats with acute keratitis. In addition, AT-RvD1 can exert as an anti-inflammatory activity by inhibiting the non-canonical pyroptosis. Hence, it may be a promising and safe agent in treating acute keratitis.

4,5-Dimethoxycanthin-6-one is a novel LSD1 inhibitor that inhibits proliferation of glioblastoma cells and induces apoptosis and pyroptosis

BackgroundGlioblastoma is one of the most common fatal intracranial malignancies. Lysine-specific demethylase 1 (LSD1) reportedly has therapeutic effects on a variety of tumors. This study explored the therapeutic effect of LSD1 inhibition on glioblastoma cell lines and the possible underlying mechanisms.MethodsThe MTT assay was utilized to screen for the sensitivity of U87, U251 and T98G cells to 4, 5-dimethoxycarrageenin-6-one. qRT-PCR and western blot were used to measure the proliferation, apoptosis, and pyroptosis signaling pathway expression to observe the effect of LSD1 inhibition on U251 and T98G cells. Flow cytometry, immunofluorescence, immunohistochemistry, wound scratch, clone formation, and TUNEL assay were used to analyze the effects of 4, 5-dimethoxycanthin-6-one on glioblastoma cells. The effect of 4, 5-dimethoxycanthin-6-one was examined in vivo in BALB/c nude mice injected with U251 cells. HE staining was used to detect the histopathology of the tumor.ResultsLSD1 specifically catalyzes the demethylation of monomethylated and demethylated histone H3 lysine at position 4 (h3k4me1, h3k4me2, h3k4me3) and lysine at position 9 (h3k9me1). This regulated the transcriptional activity of proliferation, apoptosis, and pyroptosis signaling pathway genes. In vitro, the proliferation of glioblastoma cells was decreased in the 4, 5-dimethoxycanthin-6-one group. The expression of Caspase1 in glioblastoma cells treated with 4, 5-dimethoxycanthin-6-one increased, and the number of apoptotic cells increased. The tumor volume of mice injected with 4, 5-dimethoxycanthin-6-one decreased significantly.Conclusion4, 5-Dimethoxycanthin-6-one could act as a novel inhibitor of LSD1 to regulate glioblastoma, which could inhibit the proliferation of U251 and T98G cells and induce their apoptosis and pyroptosis. It is a potential drug for the treatment of glioblastoma.

Pyrroloquinoline quinone ameliorates diabetic cardiomyopathy by inhibiting the pyroptosis signaling pathway in C57BL/6 mice and AC16 cells

PurposeDiabetic cardiomyopathy (DCM), a common complication of diabetes mellitus and is characterized by myocardial hypertrophy and myocardial fibrosis. Pyrroloquinoline quinone (PQQ), a natural nutrient, exerts strong protection against various myocardial diseases. Pyroptosis, a type of inflammation-related programmed cell death, is vital to the development of DCM. However, the protective effects of PQQ against DCM and the associated mechanisms are not clear. This study aimed to investigate whether PQQ protected against DCM and to determine the underlying molecular mechanism.MethodsDiabetes was induced in mice by intraperitoneal injection of streptozotocin, after which the mice were administered PQQ orally (10, 20, or 40 mg/kg body weight/day) for 12 weeks. AC16 human myocardial cells were divided into the following groups and treated accordingly: control (5.5 mmol/L glucose), high glucose (35 mmol/L glucose), and HG + PQQ groups (1 and 10 nmol/L PQQ). Cells were treated for 24 h.ResultsPQQ reduced myocardial hypertrophy and the area of myocardial fibrosis, which was accompanied by an increase in antioxidant function and a decrease in inflammatory cytokine levels. Moreover, myocardial hypertrophy—(ANP and BNP), myocardial fibrosis—(collagen I and TGF-β1), and pyroptosis-related protein levels decreased in the PQQ treatment groups. Furthermore, PQQ abolished mitochondrial dysfunction and the activation of NF-κB/IκB, and decreased NLRP3 inflammation-mediated pyroptosis in AC16 cells under high-glucose conditions.ConclusionPQQ improved DCM in diabetic mice by inhibiting NF-κB/NLRP3 inflammasome-mediated cell pyroptosis. Long-term dietary supplementation with PQQ may be greatly beneficial for the treatment of DCM.Graphical abstractDiagram of the underlying mechanism of the effects of PQQ on DCM. PQQ inhibits ROS generation and NF-κB activation, which stimulates activation of the NLRP3 inflammasome and regulates the expression of caspase-1, IL-1β, and IL-18. The up-regulated inflammatory cytokines trigger myocardial hypertrophy and cardiac fibrosis and promote the pathological process of DCM.

Treatment of Membranous Nephropathy by Disulfiram through Inhibition of Podocyte Pyroptosis

Introduction: Membranous nephropathy (MN) is a common chronic kidney disease in adults and a major challenge of clinical practice for its treatment. Despite major advances, since the discovery of the phospholipase A2 receptor as the major autoantigen of podocytes in MN, the mechanisms leading to glomerular damage remain elusive. Pyroptosis, a newly discovered type of programed necrotic cell death mainly mediated by gasdermin, was found to be responsible for podocyte injury in MN in our recent work. Objectives: The aim of this study was to explore the therapeutic effect of an FDA-approved drug, disulfiram (DSF), in the treatment of MN by inhibiting pyroptosis. Methods and Results: DSF significantly alleviated C3a/C5a-induced podocyte injury in vitro and renal lesions in passive Heymann nephritis (PHN) rats, as reflected by the decreased percentage of propidium iodide staining podocytes, decreased lactate dehydrogenase release from cultured podocytes and improvement in 24-h urine protein, serum albumin, serum creatinine, abnormal alterations of podocyte injury markers Desmin and WT-1 and podocyte foot process fusion in PHN rats. The protective effect of DSF on podocyte injury in vitro and in vivo can be ascribed to its inhibition of the activation and membrane translocation of the pyroptosis executor gasdermin D (GSDMD) in podocytes. DSF also inhibited the increase and activation of the pyroptosis signaling pathway NLRP3-ASC-Caspase-1/IL-18/GSDMD in C3a/C5a-treated podocytes and renal tissue of PHN rats. Conclusion: DSF is a potential drug for MN treatment, and its clinical application needs to be further investigated.

Emodin Attenuates LPS-Induced Acute Lung Injury by Inhibiting NLRP3 Inflammasome-Dependent Pyroptosis Signaling Pathway In vitro and In vivo

—Emodin, the effective component of the traditional Chinese medicine Dahuang, has anti-inflammatory effects. However, the protective effects and potential mechanisms of emodin are not clear. This study investigated the protective effects and potential mechanisms of emodin on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in vitro and in vivo. In vivo, we designed an LPS-induced ALI rat model. In vitro, we chose the J774A.1 cell line to establish an inflammatory cellular model, and knocked down NOD-like receptor family pyrin domain containing 3 (NLRP3) using small interfering RNA. The mRNA and protein expression of NLRP3, a C-terminal caspase recruitment domain (ASC), caspase 1 (CASP1), and gasdermin D (GSDMD) in cells and lung tissues were detected by western blot and real-time quantitative polymerase chain reaction (PCR). The expression levels of interleukin 1 beta (IL-1β) and IL-18 in the serum and supernatant were determined by the enzyme-linked immunosorbent assay. The degree of pathological injury in lung tissue was evaluated by hematoxylin and eosin (H&E) staining. In vitro, we demonstrated that emodin could inhibit NLRP3 and then inhibit the expression of ASC, CASP1, GSDMD, IL-1β, and IL-18. In vivo, we confirmed that emodin had protective effects on LPS-induced ALI and inhibitory effects on NLRP3 inflammasome -dependent pyroptosis. Emodin showed excellent protective effects against LPS-induced ALI by regulating the NLRP3 inflammasome-dependent pyroptosis signaling pathway.

Aluminum impairs cognitive function by activating DDX3X-NLRP3-mediated pyroptosis signaling pathway

IntroductionAluminum is a kind of chemical contaminants in food which can induce neurotoxicity. Aluminum exposure is closely related to neurodegenerative diseases (ND), in which neuroinflammation might involve. However, the molecular mechanism of aluminum-induced neuroinflammation through pyroptosis is not fully clarified yet. Material and methodsThe mice model of subacute exposure to aluminum chloride (AlCl3) was established. BV2 microglia cells was treated with AlCl3 in vitro. Resveratrol (Rsv) was adopted as intervention agent. ResultsOur results showed that aluminum induced cognitive impairment, destroying blood brain barrier (BBB), and causing nerve injury in mice. Meanwhile, aluminum could stimulate nucleotide oligomerization domain-like receptor family pyrin domain containing protein 3 (NLRP3) inflammasome assembly and activate caspase-1 (CASP1), inducing gasdermin D (GSDMD)-mediated pyroptosis signaling, releasing cytokines IL-1β and IL-18, further promoting the activation of glial cells to magnify neuroinflammatory response. Moreover, DEAD-box helicase 3 X-linked (DDX3X) and stress granule RasGAP SH3-domain-binding protein 1 (G3BP1) both participated in neuroinflammation induced by aluminum. When co-treated with Rsv, these injuries were alleviated to some extent. ConclusionAluminum exposure could induce nerve cell pyroptosis and neuroinflammation by DDX3X-NLRP3 inflammasome signaling pathway, which could be rescued via Rsv activating sirtuin 1 (SIRT1).

Beneficial impact of Nesfatin-1 on reproductive dysfunction induced by nicotine in male rats: Possible modulation of autophagy and pyroptosis signaling pathways.

This study was conducted to explore the beneficial impact of nesfatin-1 on reproductive dysfunction induced by nicotine (NT) in male rats with possible modulation of autophagy and pyroptosis signaling pathways. This research was performed on 40 Wistar male rats. They were distributed into four groups: control, normal+nesfatin-1, NT, and NT+nesfatin-1. At the end of the experimental period, the serum was separated for assay of testosterone, FSH and LH. Also, sperm parameters were determined. Histopathological examination of testicular tissue and immunohistochemical analysis was done for mammalian target of rapamycin, AMP-activated protein kinase, and mitogen-activated protein kinases including phosphorylated extracellular signal regulated kinase and phosphorylated cJun N-terminal kinase. Relative gene expression was determined for testicular nucleotide oligomerization domain (NOD)-like receptors proteins and Caspase-1, and autophagy markers including microtubule-associated protein 1 light chain 3 alpha and Beclin-1. Also, the following testicular parameters were assayed: 3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase, malondialdehyde, superoxide dismutase activity, catalase, glucose-6 phosphate dehydrogenase, reactive oxygen species, caspase-3 activity, IL-1β, IL-18, mitochondrial transmembrane potential and Complex-I activity. The results revealed that the normal+nesfatin-1 group showed insignificant changes as compared to the control group. Meanwhile, the NT group exhibited prominent reproductive dysfunction in male rats. On the other hand, in the NT+nesfatin-1 group nesfatin-1 notably attenuated this reproductive dysfunction as evidenced by improvement of hormonal assay, sperm parameters, histopathological picture, immunohistochemical evaluation and real time relative gene expressions. In conclusion: Nesfatin-1 alleviated the impairment of male reproductive functions induced by NT via enhancement of autophagy pathways, suppression of pyroptosis, apoptosis, mitochondrial dysfunction and ROS production. Thus nesfatin-1 may offer a novel protective or therapeutic access for treating male infertility.

Exenatide Attenuates Non-Alcoholic Steatohepatitis by Inhibiting the Pyroptosis Signaling Pathway.

Background/AimsExenatide is a glucagon-like polypeptide-1 analog, whose main clinical use is to treat type 2 diabetes. However, the mechanism of exenatide in mitigating non-alcoholic steatohepatitis (NASH) remains unclear. This study aimed to investigate the in vitro and in vivo effect of exenatide on NASH.MethodsLeptin receptor-deficient C57BL/KsJ- db/db male mice were fed with methionine-choline-deficient (MCD) diet for 4 weeks to induce NASH, while oleic acid/LPS-treated HepG2 cells were used as an in vitro cell model. Exenatide (20 µg/kg/day, subcutaneous) and specific exenatide inhibitors (20 µg/kg/day, intraperitoneal) were used to determine the effects of exenatide on NASH.ResultsExenatide treatment inhibited the pyroptosis signaling pathway to attenuate NASH.ConclusionTo the best of our knowledge, this report provides the first evidence showing that exenatide attenuated NASH by inhibiting the pyroptosis signaling pathway. Exenatide thus has important pathophysiological functions in NASH and may represent a useful new therapeutic target.

Pretreatment with kaempferol attenuates microglia-mediate neuroinflammation by inhibiting MAPKs–NF–κB signaling pathway and pyroptosis after secondary spinal cord injury

Spinal cord injury (SCI) is a devastating injury that characterized by oxidative stress and inflammatory response. Kaempferol is reported to be an anti-neuroinflammation in neurologic disorders. Nevertheless, the role and mechanism of kaempferol in SCI remains unclear. The present study aims to investigate effects of kaempferol on SCI and its possible underlying mechanisms in in vivo and in vitro models. A C5 hemi-contusion injury was induced in Sprague-Dawley rats to investigate the neuroprotective effects of kaempferol after SCI. For in vitro study, the BV2 microglia cell lines were pretreated with or without kaempferol. A combination of molecular and histological methods was used to clarify the mechanism and explore the signaling pathway both in vivo and in vitro. One-way analysis of variance (ANOVA) was conducted with Bonferroni post hoc tests to examine the differences between groups. The in vivo studies showed that kaempferol could improve the recovery of hindlimb motor function and ameliorate tissue damage in the spinal cord after SCI. Moreover, administration of kaempferol reduced microglia activation and oxidative stress level in the spinal cord. The in vitro studies showed that kaempferol suppressed the microglia activation resulting from the administration of LPS with ATP to BV-2 cells. Pretreated BV2 cells with kaempferol reduced the generation of reactive oxygen species (ROS) by inhibiting NADPH oxidase 4, and then, suppressed the phosphorylation of p38 MAPK and JNK, which subsequently inhibited nuclear translocation of NF-κB p65 to express pro-inflammatory factors. We also observed that kaempferol could inhibite the pyroptosis related proteins (NLRP3 Caspase-1 p10 ASC N-GSDMD) and reduce the release of IL-18 and IL-1β. In conclusion, kaempferol was able to reduce oxidative stress and inflammatory response through down-regulation of ROS dependent MAPKs- NF-κB and pyroptosis signaling pathway, which suggested that kaempferol might be a novel promising therapeutic agent for SCI.

Potential role of microRNAs in theregulation of pyroptosis (Review).

MicroRNAs (miRNAs) perform a variety of important cellular functions, including regulating the cell cycle, apoptosis and differentiation, amongst others. Recent research has demonstrated an essential function performed by miRNAs in regulating pyroptosis, which is a type of programmed cell death associated with inflammatory responses that plays a critical role in numerous diseases. Through direct or indirect action on proteins associated with the pyroptosis signaling pathway, miRNAs are involved in the pathological processes of cardiovascular, kidney and immune diseases, among others. The present review discusses the maturation process of miRNAs and the process of pyroptosis, with a specific focus on the transport of miRNAs to damaged cells via exosomes, shedding vesicles and protein stabilized complexes, as well as the role of different miRNAs in the regulation of pyroptosis through different gene and protein targets. The aim of the present review was to provide a novel insight into the regulatory role of miRNAs in pyroptosis and new treatment options for pyroptosis‑associated diseases.

Estrogen protects against liver damage in sepsis through inhibiting oxidative stress mediated activation of pyroptosis signaling pathway.

Sepsis was characterized by systemic inflammatory response and multisystem organ dysfunction, refering to the activation of inflammatory and oxidative stress pathways. Estrogen has been shown to have anti-inflammatory and antioxidant effects as well as extensive organ protective role. However, whether estrogen alleviates sepsis-induced liver injury and the mechanisms involved remain unknown. Septic mice were constructed by intraperitoneal injection lipopolysaccharide, and the effect of estrogen on liver injury was investigated. Furthermore, the roles of NLRP3 inhibitor MCC950 and mitochondrial ROS specific scavenger Mito-tempo, on the liver injury were explored in septic mice. Female septic mice exhibited liver damage with increased serum AST and ALT level as well as the existence of extensive necrosis, and which was more serious in male septic mice. Moreover, Ovariectomy (OVX) aggravated sepsis-induced liver damage and activation of pyroptosis signaling pathway, which was alleviated by estrogen as evidenced by decreased serum AST, ALT level and number of infiltrating inflammatory cell, as well as protein expression related to pyroptosis. OVX aggravated mitochondrial dysfunction and liver injury in septic mice was also partly reversed by Mito-tempo and MCC950. These results demonstrated that estrogen protected against sepsis-induced liver damage through alteration of mitochondrial function and activation of inflammatory-mediated pyroptosis signaling pathway.

Roles of the pyroptosis signaling pathway in a sepsis-associated encephalopathy cell model.

ObjectivesThe inhibition of pyroptosis has a protective effect in sepsis-associated encephalopathy (SAE). However, the mechanisms underlying pyroptosis in SAE remain to be elucidated.MethodsHere, we investigated the effects of the caspase inhibitors, Belnacasan (Beln) and Wedelolactone (Wede), on an induced model of SAE in P12 cells, using immunofluorescence, ELISA, western blotting, and flow cytometry.ResultsThe cell viability decreased, IL-1β and IL-18 secretion increased, and the levels of the caspase cleavage products, N-terminal gasdermin D, cleaved caspase-1, and cleaved caspase-11, increased in P12 cells following combined treatment with lipopolysaccharides (LPS) and adenosine triphosphate (ATP). However, treatment with Beln or Wede ameliorated the effects induced by LPS and ATP. Neither Beln nor Wede notably affected the levels of cell apoptosis-associated proteins but these inhibitors regulated the levels of cell pyroptosis-associated proteins. Further, the combination of Beln and Wede exerted greater inhibitory effects on cell pyroptosis than either Beln or Wede alone.ConclusionsThe results demonstrated that both the canonical and non-canonical signaling pathways of cell pyroptosis are involved in LPS-induced cell damage and that the non-canonical signaling pathway may be involved to a greater extent. This suggests that the inhibition of pyroptosis may exert potential therapeutic effects on SAE.

Activation of CXCR7 promotes endothelial repair and reduces the carotid atherosclerotic lesions through inhibition of pyroptosis signaling pathways

Endothelial injuries, including cell pyroptosis, are ongoing inflammatory processes with key roles in atherosclerosis development. Our previous report showed that the chemokine CXCL12 and its receptor CXCR7 are associated with the proliferation and angiogenesis of endothelial cells. Nevertheless, the mechanism underlying these effects on atherosclerotic lesions, especially on endothelial dysfunction, remains unknown. Here, we demonstrated that CXCR7 was upregulated in human carotid atherosclerotic plaques, apolipoprotein E knockout (ApoE−/−) mice fed with a high‐fat diet (HFD), and oxidized lipopolysaccharide‐treated (ox‐LDL) human umbilical vein endothelial cells (HUVECs). Further, the activation of CXCR7 reversed ox‐LDL‐induced HUVEC dysfunction, such as migration, tube formation, and cell pyroptosis; all of these protective effects were alleviated by inhibition of CXCR7. The NOD‐like receptor family pyrin domain‐containing 3 (NLRP3) inflammasomes were also elevated in human carotid atherosclerotic plaques, ApoE−/− mice fed with HFD, and ox‐LDL‐injured HUVECs by regulation of caspase‐1 and interleukin (IL)‐1β expression. The activation of CXCR7 by TC14012 led to a decrease in atherosclerotic lesions in ApoE−/− mice fed with HFD. TC14012 also inhibited the expression of the NLRP3 inflammasome signaling pathway in vivo. In conclusion, our study suggests that CXCR7 plays an important role in regulating NLRP3 inflammasome‐modulated pyroptosis in HUVECs, providing a potential novel therapy for atherosclerosis.

Role of Smad3 inhibitor and the pyroptosis pathway in spinal cord injury

The aim of the present study was to investigate the role of Smad3 inhibitors and the pyroptosis pathway in spinal cord injury, and to determine the underlying mechanism. The pyroptosis signaling pathway may be involved in spinal cord injury during the recovery period. Smad3 inhibitor may serve a role in alleviating spinal cord injury by reducing the pyroptosis of neurons, which is induced by caspase-1, absent in melanoma-2 or NOD-like receptors protein-1 during the recovery period of spinal cord injury. In the present study, spinal cord injury was alleviated by caspase-1 and Smad3 inhibitors. Therefore, a Smad3 inhibitor could relieve spinal cord injury in mice by directly downregulating caspase-1 and reducing neuron pyroptosis following spinal cord injury during the recovery period.