Structural transitions enable interleukin-18 maturation and signaling.

Several interleukin-1 (IL-1) family members, including IL-1ß and IL-18, require processing by inflammasome-associated caspases to unleash their activities. Here, we unveil, by cryoelectron microscopy (cryo-EM), two major conformations of the complex between caspase-1 and pro-IL-18. One conformation is similar to the complex of caspase-4 and pro-IL-18, with interactions at both the active site and an exosite (closed conformation), and the other only contains interactions at the active site (open conformation). Thus, pro-IL-18 recruitment and processing by caspase-1 is less dependent on the exosite than the active site, unlike caspase-4. Structure determination by nuclear magnetic resonance uncovers a compact fold of apo pro-IL-18, which is similar to caspase-1-bound pro-IL-18 but distinct from cleaved IL-18. Binding sites for IL-18 receptor and IL-18 binding protein are only formed upon conformational changes after pro-IL-18 cleavage. These studies show how pro-IL-18 is selected as a caspase-1 substrate, and why cleavage is necessary for its inflammatory activity.

Effects of idebenone and coenzyme Q10 on NLRP3/caspase-1/IL-1ß pathway regulation on ethanol-induced hepatotoxicity in rats.

Chronic and excessive alcohol consumption leads to liver toxicity. There is a need to investigate effective therapeutic strategies to alleviate alcohol-induced liver injury, which remains the leading cause of liver-related morbidity and mortality worldwide. Therefore here, we looked into and evaluated how ethanol-induced hepatotoxicity was affected by coenzyme Q10 (CoQ10) and its analog, idebenone (IDE), on the NLRP3/caspase-1/IL-1 pathway. Hepatotoxicity induced in rats through the oral administration of gradually increasing dosages of ethanol (from 2 to 6 g/kg/day) over 30 days and the effect of CoQ10 (10 or 20 mg/kg) and IDE (50 or 100 mg/kg) were evaluated. Serum hepatotoxicity markers (ALT, AST, GGT, ALP, and TBIL), tissue oxidative stress markers and the mRNA expressions of IL-1ß, IL-18, TGF-ß, NF-κB, NLRP3, and caspase-1 were evaluated. Masson's trichrome staining was also used to visualize fibrosis in the liver tissue. The results indicated that ethanol exposure led to hepatotoxicity as well as considerable NLRP3/caspase-1/IL-1ß pathway activation. Moreover, CoQ10 or IDE treatment reduced measured parameters in a dosage-dependent manner. Thus, by inhibiting the NLRP3/caspase-1/IL-1 pathway, CoQ10 and IDE can prevent the hepatotoxicity caused by ethanol, although CoQ10 is more effective than IDE. This study will provide insight into new therapeutic avenues that take advantage of the anti-inflammatory and antioxidant properties of CoQ10 and IDE in ethanol-induced liver diseases.

Interleukin 1ß receptor blocker (Anakinra) and regenerative stem cell therapy: two novel approaches effectively ameliorating diabetic cardiomyopathy.

Diabetic cardiomyopathy (DCM) is a serious common complication of diabetes. Unfortunately, there is no satisfied treatment for those patients and more studies are in critical need to cure them. Therefore, we aimed to carry out our current research to explore the role of two novel therapeutic approaches: one a biological drug aimed to block inflammatory signaling of the IL 1beta (IL1ß) axis, namely, anakinra; the other is provision of anti-inflammatory regenerative stem cells. Wistar male rats were allocated into four groups: control group: type 2 diabetes mellitus (DM) induced by 6-week high-fat diet (HFD) followed by a single-dose streptozotocin (STZ) 35 mg/kg i.p., then rats were allocated into: DM: untreated; DM BM-MSCs: received a single dose of BM-MSCs (1 × 106 cell/rat) into rat tail vein; DM-Anak received Anak 0.5 µg/kg/day i.p. for 2 weeks. Both therapeutic approaches improved cardiac performance, fibrosis, and hypertrophy. In addition, blood glucose and insulin resistance decreased, while the antioxidant parameter, nuclear factor erythroid 2-related factor 2 (Nrf2) and interleukin 10 (IL10), and anti-inflammatory agent increased. Furthermore, there is a significant reduction in tumor necrosis factor alpha (TNFα), IL1ß, caspase1, macrophage marker CD 11b, inducible nitric oxide synthase (iNOS), and T-cell marker CD 8. Both Anak and BM-MSCs effectively ameliorated inflammatory markers and cardiac performance as compared to non-treated diabetics. Improvement is mostly due to anti-inflammatory, antioxidant, anti-apoptotic properties, and regulation of TNFα/IL1ß/caspase1 and Nrf2/IL10 pathways.

The ameliorative effect of vinpocetine against gentamicin-induced uterine-injury in rats involves the inflammasome/caspase-1/IL-1ß pathway.

BACKGROUND: There is limited data regarding the hazardous effect of gentamicin (GM) on the uterus and whether or not vinpocetine (Vinpo) ameliorates it. The present study aimed to identify the possible protective effect of Vinpo in GM-induced uterine injury in rats. METHODS: Female rats were assorted in control-group, Vinpo-group, GM-group, and Vinpo plus GM group. Serum and uterine GM concentration were measured. Uterine oxidative stress parameters besides inflammatory and apoptotic biomarkers were evaluated. Uterine histopathological examination and interlukin-1beta (IL-1ß) immune-histochemical study were detected. RESULTS: GM significantly increased uterine oxidative stress, inflammatory and apoptotic biomarkers. Histopathological picture of uterine damage and increased IL-1ß immunoexpression were detected. Vinpo significantly ameliorated the distributed GM concentration, oxidative stress, inflammatory and apoptotic biomarkers with a prompt improvement in histopathological picture and a decrease in IL-1ß immunoexpression. CONCLUSION: Vinpo protective effect against GM-induced uterine injury involves modulation of inflammasome/caspase-1/IL-1ß signaling pathway.

Ruscogenin Attenuates Ulcerative Colitis in Mice by Inhibiting Caspase-1-Dependent Pyroptosis via the TLR4/NF-κB Signaling Pathway.

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders affecting the digestive tract, including ulcerative colitis and Crohn's disease. Ruscogenin, a prominent steroidal sapogenin present in radix ophiopogon japonicus, has shown a protective effect on attenuating the inflammatory response associated with inflammatory diseases, but the efficacy of ruscogenin in IBD remains unclear. The aim of this study is to explore the effect of ruscogenin on intestinal barrier dysfunction and inflammatory responses as well as the underlying mechanism in ulcerative colitis. A dextran sulfate sodium salt (DSS)-induced C57BL/6 mouse colitis model was employed for the in vivo studies, while in vitro experiments were performed in THP-1 cells and human intestinal epithelial cells involved in inducing inflammatory responses and pyroptosis using LPS/nigericin. The results indicated that ruscogenin treatment attenuated the symptoms of ulcerative colitis, reduced the release of inflammatory cytokines and the expression of pyroptosis-associated proteins, and restored the integrity of the intestinal epithelial barrier in colon tissue in mice. Moreover, ruscogenin inhibited LPS/nigericin-induced pyroptosis in THP-1 cells. Mechanically, ruscogenin inhibited NLRP3 inflammasome activation and canonical pyroptosis, at least in part, through the suppression of the TLR4/NF-κB signaling pathway. These findings might provide new insights and a solid foundation for further exploration into the therapeutic potential of ruscogenin in the treatment of IBD.

Role of Type 4B Secretion System Protein, IcmE, in the Pathogenesis of Coxiella burnetii.

Coxiella burnetii is an obligate intracellular Gram-negative bacterium that causes Q fever, a life-threatening zoonotic disease. C. burnetii replicates within an acidified parasitophorous vacuole derived from the host lysosome. The ability of C. burnetii to replicate and achieve successful intracellular life in the cell cytosol is vastly dependent on the Dot/Icm type 4B secretion system (T4SSB). Although several T4SSB effector proteins have been shown to be important for C. burnetii virulence and intracellular replication, the role of the icmE protein in the host-C. burnetii interaction has not been investigated. In this study, we generated a C. burnetii Nine Mile Phase II (NMII) mutant library and identified 146 transposon mutants with a single transposon insertion. Transposon mutagenesis screening revealed that disruption of icmE gene resulted in the attenuation of C. burnetii NMII virulence in SCID mice. ELISA analysis indicated that the levels of pro-inflammatory cytokines, including interleukin-1ß, IFN-γ, TNF-α, and IL-12p70, in serum from Tn::icmE mutant-infected SCID mice were significantly lower than those in serum from wild-type (WT) NMII-infected mice. Additionally, Tn::icmE mutant bacteria were unable to replicate in mouse bone marrow-derived macrophages (MBMDM) and human macrophage-like cells (THP-1). Immunoblotting results showed that the Tn::icmE mutant failed to activate inflammasome components such as IL-1ß, caspase 1, and gasdermin-D in THP-1 macrophages. Collectively, these results suggest that the icmE protein may play a vital role in C. burnetii virulence, intracellular replication, and activation of inflammasome mediators during NMII infection.

The protease caspase-1: Activation pathways and functions.

Caspase-1 is one of the main mediators of inflammatory caspases and has become a correspondent with inflammation, cell death, and several inflammatory diseases. In this review, we systematically summarize both original and recent advances in caspase-1 to provide references for a better understanding of the molecular mechanisms in its activation and functions. This study investigates and summarizes the published articles concerning caspase-1, inflammation, pyroptosis, apoptosis, and cell death by searching academic search systems, including the PubMed, Web of Science, and Google Scholar. Caspase-1 is one of the main mediators of inflammatory caspases and has become a correspondent with inflammation and cell death. In cell death, caspase-1 was originally found to cause apoptosis in fibroblasts. Importantly, caspase-1 was later reported to execute programmed cell death, including pyroptosis and apoptosis, in many immune cells in response to diverse stimuli. It is widely established that different pathways can activate caspase-1 and subsequently mediate cell death and inflammation. It has become increasingly clear that caspase-1 is responsible for the initiation and control of pyroptosis, apoptosis, and inflammation in addition to its well-known function in cleaving IL-1ß. The significant advancement in the understanding of caspase-1-controlled cell death and novel substrates inspires new therapeutic approaches in the future.

Initial Despair and Current Hope of Identifying a Clinically Useful Treatment of Myocardial Reperfusion Injury: Insights Derived from Studies of Platelet P2Y12 Antagonists and Interference with Inflammation and NLRP3 Assembly.

Myocardial necrosis following the successful reperfusion of a coronary artery occluded by thrombus in a patient presenting with ST-elevation myocardial infarction (STEMI) continues to be a serious problem, despite the multiple attempts to attenuate the necrosis with agents that have shown promise in pre-clinical investigations. Possible reasons include confounding clinical risk factors, the delayed application of protective agents, poorly designed pre-clinical investigations, the possible effects of routinely administered agents that might unknowingly already have protected the myocardium or that might have blocked protection, and the biological differences of the myocardium in humans and experimental animals. A better understanding of the pathobiology of myocardial infarction is needed to stem this reperfusion injury. P2Y12 receptor antagonists minimize platelet aggregation and are currently part of the standard treatment to prevent thrombus formation and propagation in STEMI protocols. Serendipitously, these P2Y12 antagonists also dramatically attenuate reperfusion injury in experimental animals and are presumed to provide a similar protection in STEMI patients. However, additional protective agents are needed to further diminish reperfusion injury. It is possible to achieve additive protection if the added intervention protects by a mechanism different from that of P2Y12 antagonists. Inflammation is now recognized to be a critical factor in the complex intracellular response to ischemia and reperfusion that leads to tissue necrosis. Interference with cardiomyocyte inflammasome assembly and activation has shown great promise in attenuating reperfusion injury in pre-clinical animal models. And the blockade of the executioner protease caspase-1, indeed, supplements the protection already seen after the administration of P2Y12 antagonists. Importantly, protective interventions must be applied in the first minutes of reperfusion, if protection is to be achieved. The promise of such a combination of protective strategies provides hope that the successful attenuation of reperfusion injury is attainable.

Staphylococcus Aureus Membrane Vesicles Kill Tumor Cells Through a Caspase-1-Dependent Pyroptosis Pathway.

Introduction: Nanosized outer membrane vesicles (OMVs) from Gram-negative bacteria have attracted increasing interest because of their antitumor activity. However, the antitumor effects of MVs isolated from Gram-positive bacteria have rarely been investigated. Methods: MVs of Staphylococcus aureus USA300 were prepared and their antitumor efficacy was evaluated using tumor-bearing mouse models. A gene knock-in assay was performed to generate luciferase Antares2-MVs for bioluminescent detection. Cell counting kit-8 and lactic dehydrogenase release assays were used to detect the toxicity of the MVs against tumor cells in vitro. Active caspase-1 and gasdermin D (GSDMD) levels were determined using Western blot, and the tumor inhibition ability of MVs was determined in B16F10 cells treated with a caspase-1 inhibitor. Results: The vesicular particles of S. aureus USA300 MVs were 55.23 ± 8.17 nm in diameter, and 5 µg of MVs remarkably inhibited the growth of B16F10 melanoma in C57BL/6 mice and CT26 colon adenocarcinoma in BALB/c mice. The bioluminescent signals correlated well with the concentrations of the engineered Antares2-MVs (R2 = 0.999), and the sensitivity for bioluminescence imaging was 4 × 10-3 µg. Antares2-MVs can directly target tumor tissues in vivo, and 20 µg/mL Antares2-MVs considerably reduced the growth of B16F10 and CT26 tumor cells, but not non-carcinomatous bEnd.3 cells. MV treatment substantially increased the level of active caspase-1, which processes GSDMD to trigger pyroptosis in tumor cells. Blocking caspase-1 activation with VX-765 significantly protected tumor cells from MV killing in vitro and in vivo. Conclusion: S. aureus MVs can kill tumor cells by activating the pyroptosis pathway, and the induction of pyroptosis in tumor cells is a promising strategy for cancer treatment.

Correlation between abnormal cellular immune and changes of magnetic resonance spectroscopy in patients with Alzheimer's disease.

BACKGROUND: Evidence from previous studies indicates that neuroinflammation contributes to the onset of Alzheimer's Disease (AD). Moreover, cellular dysfunction is induced by impaired signaling of neurotransmitters. This study aimed to explore the correlation between cellular immune dysfunction and neurotransmitter changes through cranial Magnetic Resonance Spectroscopy (MRS) in AD patients. METHODS: Here, 32 AD, 40 Vascular Dementia (VD), and 35 Non-Dementia Elderly Control (NDE) cases were enrolled. Flow cytometry was performed to characterize lymphocyte subsets in plasma samples. The IL-1ß and Caspase-1 levels were detected by ELISA. The NLRP3 expression level was measured by Western Blot (WB). The equivalence of N-acetylaspartate (NAA), Creatine (Cr), Choline (Cho), and Inositol (MI) in bilateral hippocampi of patients was examined by MRS. The association of NAA/Cr or MI/Cr ratios with the proportion of T lymphocyte subsets or NK cell subsets was determined through single-factor correlation analysis. RESULTS: The proportion of T lymphocyte subsets was significantly lower in the AD group than in the NDE group (P < 0.01). On the other hand, the Caspase-1, NLRP3, and IL-1ß protein expression levels were significantly higher in the AD group than in the other groups. Further analysis showed that the NAA/Cr ratio was lower in the AD group than in the NDE group. Additionally, a significant positive correlation was found between the NAA/Cr ratio and the MMSE score (r = 0.81, P < 0.01). Moreover, a significant positive correlation was observed between the NAA/Cr and T lymphocyte ratios. The NAA/Cr ratio was significantly negatively correlated with the proportion of NK cells in the blood (r = ï¼0.83, P < 0.01). A significant negative correlation was also recorded between the MI/Cr and T cell ratios in blood samples. CONCLUSIONS: Impaired cellular immune dysfunction in AD patients was significantly correlated with abnormal MRS. Neuroimmune dysfunction may contribute to the pathogenesis of AD and alter the metabolism of neurotransmitters such as aspartic acid and MI in the brains of AD patients. TRIAL REGISTRATION: Not applicable.

Mechanism of dexmedetomidine protection against cisplatin induced acute kidney injury in rats.

OBJECTIVE: This study explored the molecular mechanisms by which dexmedetomidine (Dex) alleviates cisplatin (CP)-induced acute kidney injury (AKI) in rats. METHODS: CP-induced AKI models were established, and Dex was intraperitoneally injected at different concentrations into rats in the model groups. Subsequently, rats were assigned to the control, CP, CP + Dex 10 µg/kg, and CP + Dex 25 µg/kg groups. After weighing the kidneys of the rats, the kidney arterial resistive index was calculated, and CP-induced AKI was evaluated. In addition, four serum biochemical indices were measured: histopathological damage in rat kidneys was detected; levels of inflammatory factors, interleukin (IL)-1ß, IL-18, IL-6, and tumor necrosis factor alpha, in kidney tissue homogenate of rats were assessed through enzyme-linked immunosorbent assay (ELISA); and levels of NLRP-3, caspase-1, cleaved caspase-1, gasdermin D (GSDMD), and GSDMD-N in kidney tissues of rats were determined via western blotting. RESULTS: Dex treatment reduced nephromegaly and serum clinical marker upregulation caused by CP-induced AKI. In addition, hematoxylin and eosin staining revealed that Dex treatment relieved CP-induced kidney tissue injury in AKI rats. ELISA analyses demonstrated that Dex treatment reduced the upregulated levels of proinflammatory cytokines in the kidney tissue of AKI rats induced by CP, thereby alleviating kidney tissue injury. Western blotting indicated that Dex alleviated CP-induced AKI by inhibiting pyroptosis mediated by NLRP-3 and caspase-1. CONCLUSION: Dex protected rats from CP-induced AKI, and the mechanism may be related to NLRP-3/Caspase-1-mediated pyroptosis.

Nucleoside-diphosphate kinase of uropathogenic Escherichia coli inhibits caspase-1-dependent pyroptosis facilitating urinary tract infection.

Uropathogenic Escherichia coli (UPEC) is the most common causative agent of urinary tract infection (UTI). UPEC invades bladder epithelial cells (BECs) via fusiform vesicles, escapes into the cytosol, and establishes biofilm-like intracellular bacterial communities (IBCs). Nucleoside-diphosphate kinase (NDK) is secreted by pathogenic bacteria to enhance virulence. However, whether NDK is involved in UPEC pathogenesis remains unclear. Here, we find that the lack of ndk impairs the colonization of UPEC CFT073 in mouse bladders and kidneys owing to the impaired ability of UPEC to form IBCs. Furthermore, we demonstrate that NDK inhibits caspase-1-dependent pyroptosis by consuming extracellular ATP, preventing superficial BEC exfoliation, and promoting IBC formation. UPEC utilizes the reactive oxygen species (ROS) sensor OxyR to indirectly activate the regulator integration host factor, which then directly activates ndk expression in response to intracellular ROS. Here, we reveal a signaling transduction pathway that UPEC employs to inhibit superficial BEC exfoliation, thus facilitating acute UTI.

Prognostic significance of pyroptosis-associated molecules in endometrial cancer: a comprehensive immunohistochemical analysis.

Introduction: Endometrial cancer, the most prevalent malignancy of the female genital tract, has a concerningly poor prognosis when diagnosed in advanced stages, with limited targeted therapy options available for advanced or recurrent cases. Pyroptosis, a type of nonapoptotic cell death mediated by caspase-1, has shown potential antitumor effects in various tumors. NLRP3, a cytosolic sensor, initiates the canonical pyroptotic pathway, leading to caspase-1 activation, subsequent gasdermin D cleavage, and plasma membrane pore formation. The ESCRT-III machinery, particularly CHMP4B, acts as a key inhibitor of pyroptosis by repairing gasdermin D-induced membrane damage. The current study aimed to evaluate the clinicopathologic relevance of key pyroptosis-associated molecules in endometrial cancer. Methods: Immunohistochemistry was used to assess the expression of four pyroptosis-associated molecules (NLRP3, cleaved caspase-1 p20, cleaved gasdermin D, and CHMP4B) in 351 patients with endometrial cancer, and their associations with clinical, pathological, and survival outcomes were analyzed. Results: High NLRP3 expression was significantly associated with age ≤ 50 years and premenopause. Increased cleaved caspase-1 p20 expression was associated with nonendometrioid carcinoma, Federation of Gynaecology and Obstetrics (FIGO) grade 3, and the p53 mutant pattern and was independently associated with poor recurrence-free survival (RFS) and overall survival. Increased cleaved gasdermin D expression was associated with a body mass index of >25 kg/m², FIGO grades 1-2, early FIGO stage (I-II), and absence of lymph node metastasis. High CHMP4B expression was associated with nonendometrioid carcinoma and poor RFS. Cleaved gasdermin D-high/CHMP4B-low endometrial cancer was associated with endometrioid carcinoma, FIGO grades 1-2 and favorable RFS. Discussion: Our study identified cleaved caspase-1 p20 as an independent predictor of adverse outcomes in endometrial cancer. CHMP4B, an inhibitor of pyroptosis, was associated with an unfavorable RFS, whereas high cleaved gasdermin D/low CHMP4B expression was associated with a favorable RFS. These findings underscore the prognostic significance of pyroptosis and the potential interaction between cleaved gasdermin D and CHMP4B in endometrial cancer.

Extracellular vesicles mediate inflammasome signaling in the brain and heart of Alzheimer's disease mice.

Introduction: Alzheimer's disease (AD) is an inflammatory neurodegenerative disease characterized by memory loss and cognitive impairment that worsens over time. AD is associated with many comorbidities, including cardiovascular disease that are associated with poorer outcomes. Comorbidities, especially heart disease and stroke, play a significant role in the demise of AD patients. Thus, it is important to understand how comorbidities are linked to AD. We have previously shown that extracellular vesicle (EV)-mediated inflammasome signaling plays an important role in the pathogenesis of brain injury and acute lung injury after traumatic brain injury. Methods: We analyzed the cortical, hippocampal, ventricular, and atrial protein lysates from APP/PS1 mice and their respective controls for inflammasome signaling activation. Additionally, we analyzed serum-derived EV for size, concentration, and content of inflammasome proteins as well as the EV marker CD63. Finally, we performed conditioned media experiments of EV from AD patients and healthy age-matched controls delivered to cardiovascular cells in culture to assess EV-induced inflammation. Results: We show a significant increase in Pyrin, NLRP1, caspase-1, and ASC in the brain cortex whereas caspase-8, ASC, and IL-1ß were significantly elevated in the heart ventricles of AD mice when compared to controls. We did not find significant differences in the size or concentration of EV between groups, but there was a significant increase of caspase-1 and IL-1ß in EV from AD mice compared to controls. In addition, conditioned media experiments of serum-derived EV from AD patients and age-matched controls delivered to cardiovascular cells in culture resulted in inflammasome activation, and significant increases in TNF-α and IL-2. Conclusion: These results indicate that EV-mediated inflammasome signaling in the heart may play a role in the development of cardiovascular diseases in AD patients.

Mechanism of sodium butyrate, a metabolite of gut microbiota, regulating cardiac fibroblast transdifferentiation via the NLRP3/Caspase-1 pyroptosis pathway.

BACKGROUND: Cardiac fibroblasts (CFs) are activated after initial injury, and then differentiate into myofibroblasts (MFs), which play a pivotal role as the primary mediator cells in pathological remodeling. Sodium butyrate (NaB), being a metabolite of gut microbiota, exhibits anti-inflammatory property in local therapies on sites other than the intestine. Thus, this study aimed to probe the mechanism by which NaB regulates CFs transdifferentiation through the NLRP3/Caspase-1 pyroptosis pathway. METHODS: CFs were cultured in vitro and induced into MFs by TGFß1. CFs were identified by immunofluorescence labelling technique of vimentin and α-SMA, followed by treatment with NaB or NLRP3 inflammasome inhibitor (CY-09) and its activator [nigericin sodium salt (NSS)]. The expression levels of α-SMA, GSDMD-N/NLRP3/cleaved Caspase-1 proteins, and inflammatory factors IL-1ß/IL-18/IL-6/IL-10 were determined using immunofluorescence, Western blot and ELISA. Cell proliferation and migration were evaluated using the CCK-8 assay and the cell scratch test, respectively. RESULTS: Following the induction of TGFß1, CFs exhibited increased expression levels of α-SMA proteins and IL-6/IL-10, as well as cell proliferative and migratory abilities. TGFß1 induced CFs to differentiate into MFs, while NaB inhibited this differentiation. NaB inactivated the NLRP3/Caspase-1 pyroptosis pathway. CY-09 demonstrated inhibitory effects on the NLRP3/Caspase-1 pyroptosis pathway, leading to a reduction in TGFß1-induced CFs transdifferentiation. NSS activated the NLRP3/Caspase-1 pyroptosis pathway, and thus partially counteracting the inhibitory effect of intestinal microbiota metabolite NaB on CFs transdifferentiation. CONCLUSION: NaB, a metabolite of the gut microbiota, inhibited the activation of the NLRP3/Caspase-1 pyroptosis pathway in TGFß1-induced CFs, repressed the transdifferentiation of CFs into MFs.

Cardiac hypertrophy that affects hyperthyroidism occurs independently of the NLRP3 inflammasome.

Cardiac hypertrophy (CH) is an adaptive response to maintain cardiac function; however, persistent stress responses lead to contractile dysfunction and heart failure. Although inflammation is involved in these processes, the mechanisms that control cardiac inflammation and hypertrophy still need to be clarified. The NLRP3 inflammasome is a cytosolic multiprotein complex that mediates IL-1ß production. The priming step of NLRP3 is essential for increasing the expression of its components and occurs following NF-κB activation. Hyperthyroidism triggers CH, which can progress to maladaptive CH and even heart failure. We have shown in a previous study that thyroid hormone (TH)-induced CH is linked to the upregulation of S100A8, leading to NF-κB activation. Therefore, we aimed to investigate whether the NLRP3 inflammasome is involved in TH-induced CH and its potential role in CH pathophysiology. Hyperthyroidism was induced in NLRP3 knockout (NLRP3-KO), Caspase-1-KO and Wild Type (WT) male mice of the C57Bl/6J strain, aged 8-12 weeks, by triiodothyronine (7 µg/100 g BW, i.p.) administered daily for 14 days. Morphological and cardiac functional analysis besides molecular assays showed, for the first time, that TH-induced CH is accompanied by reduced NLRP3 expression in the heart and that it occurs independently of the NLRP3 inflammasome and caspase 1-related pathways. However, NLRP3 is important for the maintenance of basal cardiac function since NLRP3-KO mice had impaired diastolic function and reduced heart rate, ejection fraction, and fractional shortening compared with WT mice.

Lentinus edodes mycelium polysaccharide inhibits AGEs-induced HUVECs pyroptosis by regulating LncRNA MALAT1/miR-199b/mTOR axis and NLRP3/Caspase-1/GSDMD pathway.

A novel Lentinus edodes mycelia polysaccharide (LMP) prepared in our laboratory has been identified to be effective in inhibiting the damage of islet ß cells induced by glucose toxicity. However, whether it can effectively alleviate the pyroptosis of human umbilical vein endothelial cells (HUVECs) induced by advanced glycation end products (AGEs) remains unclear. Bioinformatics and cell biology techniques were used to explore the mechanism of LMP inhibiting AGEs-induced HUVECs damage. The results indicated that AGEs significantly increased the expression of LncRNA MALAT1, decreased cell viability to 79.67 %, increased intracellular ROS level to 248.19 % compared with the control group, which further led to cell membrane rupture. The release of LDH in cellular supernatant was increased to 149.42 %, and the rate of propidium iodide staining positive cells increased to 277.19 %, indicating the cell pyroptosis occurred. However, the above trend was effectively retrieved after the treatment with LMP. LMP effectively decreased the expression of LncRNA MALAT1 and mTOR, promoted the expression of miR-199b, inhibited AGEs-induced HUVECs pyroptosis by regulating the NLRP3/Caspase-1/GSDMD pathway. LncRNA MALAT1 might be a new target for LMP to inhibit AGEs-induced HUVECs pyroptosis. This study manifested the role of LMP in improving diabetes angiopathy and broadens the application of polysaccharide.

Caspase-1 Deficiency Modulates Adipogenesis through Atg7-Mediated Autophagy: An Inflammatory-Independent Mechanism.

Obesity stands as a significant risk factor for type 2 diabetes, hyperlipidemia, and cardiovascular diseases, intertwining increased inflammation and decreased adipogenesis with metabolic disorders. Studies have highlighted the correlation between Caspase-1 and inflammation in obesity, elucidating its essential role in the biological functions of adipose tissue. However, the impact of Caspase-1 on adipogenesis and the underlying mechanisms remain largely elusive. In our study, we observed a positive correlation between Caspase-1 expression and obesity and its association with adipogenesis. In vivo experiments revealed that, under normal diet conditions, Caspase-1 deficiency improved glucose homeostasis, stimulated subcutaneous adipose tissue expansion, and enhanced adipogenesis. Furthermore, our findings indicate that Caspase-1 deficiency promotes the expression of autophagy-related proteins and inhibits autophagy with 3-MA or CQ blocked Caspase-1 deficiency-induced adipogenesis in vitro. Notably, Caspase-1 deficiency promotes adipogenesis via Atg7-mediated autophagy activation. In addition, Caspase-1 deficiency resisted against high-fat diet-induced obesity and glucose intolerance. Our study proposes the downregulation of Caspase-1 as a promising strategy for mitigating obesity and its associated metabolic disorders.

The NLR family of innate immune and cell death sensors.

Nucleotide-binding oligomerization domain (NOD)-like receptors, also known as nucleotide-binding leucine-rich repeat receptors (NLRs), are a family of cytosolic pattern recognition receptors that detect a wide variety of pathogenic and sterile triggers. Activation of specific NLRs initiates pro- or anti-inflammatory signaling cascades and the formation of inflammasomes-multi-protein complexes that induce caspase-1 activation to drive inflammatory cytokine maturation and lytic cell death, pyroptosis. Certain NLRs and inflammasomes act as integral components of larger cell death complexes-PANoptosomes-driving another form of lytic cell death, PANoptosis. Here, we review the current understanding of the evolution, structure, and function of NLRs in health and disease. We discuss the concept of NLR networks and their roles in driving cell death and immunity. An improved mechanistic understanding of NLRs may provide therapeutic strategies applicable across infectious and inflammatory diseases and in cancer.

Paeonol attenuates nonalcoholic steatohepatitis by regulating intestinal flora and AhR/NLRP3/Caspase-1 metabolic pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Non-alcoholic steatohepatitis (NASH) is a common metabolic liver injury disease that is closely associated with obesity and metabolic disorders. Paeonol, an active ingredient found in Moutan Cortex, a traditional Chinese medicine which exhibits significant therapeutic effect on liver protection, has shown promising effects in treating liver diseases, particularly NASH. However, the specific intervention mechanism of paeonol on NASH is still unknown. AIM OF THE STUDY: Our objective is to elucidate the pharmacological mechanism of paeonol in intervening NASH at the in vivo level, focusing on the impact on intestinal flora, tryptophan-related targeted metabolome, and related Aryl hydrocarbon receptor (AhR) pathways. MATERIALS AND METHODS: Here, we explored the intervention effect of paeonol on NASH by utilizing the NASH mouse model. The Illumina highthroughput sequencing technology was preformed to determine the differences of gut microbiota of model and paeonol treatment group. The concentration of Indoleacetic acid is determined by ELISA. The intervention effect of NASH mouse and AhR/NLRP3/Caspase-1 metabolic pathway is analyzed by HE staining, oil red O staining, Immunohistochemistry, Immunofluorescence, Western blot and qRT-PCR assays. Fecal microbiota transplantation experiment also was performed to verify the intervention effect of paeonol on NASH by affecting gut microbiota. RESULTS: Firstly, we discovered that paeonol effectively reduced liver pathology and blood lipid levels in NASH mice, thereby intervening in the progression of NASH. Subsequently, through 16S meta-analysis, we identified that paeonol can effectively regulate the composition of intestinal flora in NASH mice, transforming it to resemble that of normal mice. Specifically, paeonol decreased the abundance of certain Gram-negative tryptophan-metabolizing bacteria. Moreover, we discovered that paeonol significantly increased the levels of metabolites Indoleacetic acid, subsequently enhancing the expression of AhR-related pathway proteins. This led to the inhibition of the NOD-like receptor protein 3 (NLRP3) inflammasome production and inflammation generation in NASH. Lastly, we verified the efficacy of paeonol in intervening NASH by conducting fecal microbiota transplantation experiments, which confirmed its role in promoting the AhR/NLRP3/cysteinyl aspartate specific proteinase (Caspase-1) pathway. CONCLUSIONS: Our findings suggest that paeonol can increase the production of Indoleacetic acid by regulating the gut flora, and promote the AhR/NLRP3/Caspase-1 metabolic pathway to intervene NASH.