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NLRP3 inflammasome-mediated pyroptosis contributes to the pathogenesis of non-ischemic dilated cardiomyopathy.

ABSTRACT: Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure, and the underlying mechanism remains largely elusive. Here we investigated whether NLRP3 inflammasome-mediated pyroptosis contributes to non-ischemic DCM and dissected the underlying mechanism. We found that hyper activated NLRP3 inflammasome with pyroptotic cell death of cardiomyocytes were presented in the myocardial tissues of DCM patients, which were negatively correlated with cardiac function. Doxorubicin (Dox)-induced DCM characterization disclosed that NLRP3 inflammasome activation and pyroptosis occurred in Dox-treated heart tissues, but were very marginal in either NLRP3-/- or caspase-1-/- mice. Mechanistically, Dox enhanced expressions of NOX1 and NOX4 and induced mitochondrial fission through dynamin-related protein 1 (Drp1) activation, leading to NLRP3 inflammasome-mediated pyroptosis in cardiomyocytes via caspase-1-dependent manner. Conversely, both inhibitions of NOX1 and NOX4 and Drp1 suppressed Dox-induced NLPR3 inflammasome activation and pyroptosis. The alterations of NOX1 and NOX4 expression, Drp1 phosphorylation and mitochondrial fission were validated in DCM patients and mice. Importantly, Dox-induced Drp1-mediated mitochondrial fission and the consequent NLRP3 inflammasome activation and pyroptosis were reversed by NOX1 and NOX4 inhibition in mice. This study demonstrates for the first time that cardiomyocyte pyroptosis triggered by NLRP3 inflammasome activation via caspase-1 causally contributes to myocardial dysfunction progression and DCM pathogenesis.

SUBMITTER: Zeng C

PROVIDER: S-EPMC7327979 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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NLRP3 inflammasome-mediated pyroptosis contributes to the pathogenesis of non-ischemic dilated cardiomyopathy.

Zeng Cheng C Duan Fengqi F Hu Jia J Luo Bin B Huang Binlong B Lou Xiaoying X Sun Xiuting X Li Hongyu H Zhang Xuanhong X Yin Shengli S Tan Hongmei H

Redox biology 20200330

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure, and the underlying mechanism remains largely elusive. Here we investigated whether NLRP3 inflammasome-mediated pyroptosis contributes to non-ischemic DCM and dissected the underlying mechanism. We found that hyper activated NLRP3 inflammasome with pyroptotic cell death of cardiomyocytes were presented in the myocardial tissues of DCM patients, which were negatively correlated with cardiac function. Doxorubicin (Dox)- ...[more]

PMID: 32273259

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Project description:PurposeFungal keratitis is a sight-threatening corneal infection caused by fungal pathogens, and the pathogenic mechanisms have not been fully elucidated. The aim of this study was to determine whether NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated pyroptosis contributes to Candida albicans (C. albicans) keratitis and explore the underlying mechanism.MethodsAn in vivo mouse model of C. albicans keratitis and an in vitro culture model of human corneal epithelial cells (HCECs) challenged with heat-killed C. albicans (HKCA) were established in this study. The degree of corneal infection was evaluated by clinical scoring. Gene expression was assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis or immunofluorescence staining was performed to evaluate protein expression. TdT-mediated dUTP nick end labeling (TUNEL) staining was performed to examine the pyroptotic cell death. A lactate dehydrogenase (LDH) release assay was performed to assess cytotoxicity.ResultsCompared with the mock-infected group, we observed that the mRNA levels of NLRP3, caspase-1 (CASP1), interleukin (IL)-1β and gasdermin-D (GSDMD) in C. albicans-infected mice cornea was significantly increased. Our data also demonstrated that the protein expression of NLRP3 and the pyroptosis-related markers apoptosis-associated speck-like protein containing a CARD (ASC), cleaved CASP1, N-GSDMD, cleaved IL-1β and cleaved IL-18 as well as pyroptotic cell death were dramatically elevated in the mouse model of C. albicans keratitis. More importantly, NLRP3 knockdown markedly alleviated pyroptosis and consequently reduced corneal inflammatory reaction in C. albicans keratitis. In vitro, the presence of activated NLRP3 inflammasome and pyroptotic cell death were validated in HCECs exposed to HKCA. Furthermore, the potassium (K+) channel inhibitor glyburide decreased LDH release and suppressed NLRP3 inflammasome activation and pyroptosis in HCECs exposed to HKCA.ConclusionIn conclusion, the current study revealed for the first time that NLRP3 inflammasome activation and pyroptosis occur in C. albicans-infected mouse corneas and HCECs. Moreover, NLRP3 inflammasome-mediated pyroptosis signaling is involved in the disease severity of C. albicans keratitis. Therefore, This NLRP3 inflammasome-dependent pathway may be an attractive target for the treatment of fungal keratitis.

Project description:AimsAccumulating evidence has suggested that airborne fine particulate matter (PM2.5) exposure is associated with an increased risk of ischemic stroke. However, the underlying mechanisms have not been fully elucidated. In this study, we aim to investigate the role and mechanisms of NLRP3 inflammasome and pyroptosis in ischemic stroke after PM2.5 exposure.MethodsThe BV-2 and HMC-3 microglial cell lines were established and subjected to oxygen-glucose deprivation and reoxygenation (OGD/R) with or without PM2.5 exposure. We used the CCK-8 assay to explore the effects of PM2.5 on cell viability of BV-2 and HMC-3 cells. Then, the effects of PM2.5 exposure on NLRP3 inflammasome and pyroptosis following OGD/R were detected by western blotting, ELISA, and the confocal immunofluorescence staining. Afterwards, NLRP3 was knocked down to further validate the effects of PM2.5 on cell viability, NLRP3 inflammasome activation, and pyroptosis after OGD/R in HMC-3 cells. Finally, the intracellular reactive oxygen species (ROS) was measured and the ROS inhibitor N-acetyl-L-cysteine (NAC) was used to investigate whether ROS was required for PM2.5-induced NLRP3 inflammasome activation and pyroptosis under ischemic conditions.ResultsWe found that PM2.5 exposure decreased the viability of BV-2 and HMC-3 cells in a dose- and time-dependent manner under ischemic conditions. Furthermore, PM2.5 exposure aggravated NLRP3 inflammasome activation and pyroptosis after OGD/R, as indicated by an increased expression of NLRP3, ASC, pro-caspase-1, Caspase-1, GSDMD, and GSDMD-N; increased production of IL-1β and IL-18; and enhanced Caspase-1 activity and SYTOX green uptake. However, shRNA NLRP3 treatment attenuated the effects of PM2.5 on cell viability, NLRP3 inflammasome activation, and pyroptosis. Moreover, we observed that PM2.5 exposure increased the production of intracellular ROS following OGD/R, while inhibiting ROS production with NAC partially attenuated PM2.5-induced NLRP3 inflammasome activation and pyroptosis under ischemic conditions.ConclusionThese results suggested that PM2.5 exposure triggered the activation of NLRP3 inflammasome and pyroptosis under ischemic conditions, which may be mediated by increased ROS production after ischemic stroke. These findings may provide a more enhanced understanding of the interplay between PM2.5 and neuroinflammation and cell death, and reveal a novel mechanism of PM2.5-mediated toxic effects after ischemic stroke.

Project description:BackgroundAcute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in many critically ill patients. Although inflammasome activation plays an important role in the induction of acute lung injury (ALI) and ARDS, the regulatory mechanism of this process is still unclear. When cells are stimulated by inflammation, the integrity and physiological function of mitochondria play a crucial part in pyroptosis. However, the underlying mechanisms and function of mitochondrial proteins in the process of pyroptosis are largely not yet known. Here, we identified the 18-kDa translocator protein (TSPO), a mitochondrial outer membrane protein, as an important mediator regulating nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in macrophages during ALI.MethodsTSPO gene knockout (KO) and lipopolysaccharide (LPS)-induced ALI/ARDS mouse models were employed to investigate the biological role of TSPO in the pathogenesis of ARDS. Murine macrophages were used to further characterize the effect of TSPO on the NLRP3 inflammasome pathway. Activation of NLRP3 inflammasome was preformed through LPS + adenosine triphosphate (ATP) co-stimulation, followed by detection of mitochondrial membrane potential, reactive oxygen species (ROS) production, and cell death to evaluate the potential biological function of TSPO. Comparisons between two groups were performed with a two-sided unpaired t -test.ResultsTSPO- KO mice exhibited more severe pulmonary inflammation in response to LPS-induced ALI. TSPO deficiency resulted in enhanced activation of the NLRP3 inflammasome pathway, promoting more proinflammatory cytokine production of macrophages in LPS-injured lung tissue, including interleukin (IL)-1β, IL-18, and macrophage inflammatory protein (MIP)-2. Mitochondria in TSPO -KO macrophages tended to depolarize in response to cellular stress. The increased production of mitochondrial damage-associated molecular pattern led to enhanced mitochondrial membrane depolarization and pyroptosis in TSPO -KO cells.ConclusionTSPO may be the key regulator of cellular pyroptosis, and it plays a vital protective role in ARDS occurrence and development.

Project description:BackgroundAirway remodeling and inflammation are considered the main characteristics of chronic obstructive pulmonary disease (COPD). Cigarette smoke promotes the occurrence of inflammation, oxidative stress, and pyroptosis. Halotherapy has been shown to dilute secretions in the airways and promote drainage, but the mechanism remains unclear. In this study, we evaluated the anti-inflammatory and antioxidant effects of halotherapy in COPD rats and investigated the underlying mechanism.MethodsA COPD rat model was constructed by cigarette smoke and lipopolysaccharide tracheal instillation. A total of 120 male Sprague-Dawley (SD) rats were randomly divided into control, model, halotherapy, terbutaline, halotherapy + terbutaline, and Ac-YVAD-CMK (Caspase-1 inhibitor) groups. After modeling and treatment, the pulmonary function of the rats was measured. Pathological changes in the lungs were measured by hematoxylin-eosin (H&E) staining. Serum interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4), and nitric oxide (NO) levels were determined using enzyme-linked immunosorbent assay (ELISA) kits. Malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity in the lungs were determined by biochemical tests. The levels of cluster of differentiation 4 (CD4+) and CD8+ T cells in the blood were determined by flow cytometry. The expression levels of Toll-like receptor 4 (TLR4), nuclear factor kappa B (NF-κB), gasdermin-D (GSDMD), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), Caspase-1, and IL-1β in lung tissues were detected by immunohistochemistry, Western blotting, or quantitative polymerase chain reaction (qPCR).ResultsHalotherapy recovered the clinical symptoms of COPD rats, and reduced lung inflammatory cell infiltration and air wall attenuation. It also relieved oxidative stress in the lung tissue of COPD rats, reduced CD4+ and CD8+ T cell accumulation in lung tissue, and decreased inflammatory factor production in the serum of COPD rats. Furthermore, it inhibited the TLR4/NF-κB/GSDMD and NLRP3/ASC/Caspase-1 signaling pathways. Ac-YVAD-CMK could not completely inhibit the therapeutic effect of halotherapy on COPD rats.ConclusionsHalotherapy improves lung function by inhibiting the NLRP3/ASC/Caspase-1 signaling pathway to reduce inflammation and pyroptosis in COPD rats, and may be a new option for the prevention and treatment of COPD.

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NLRP3 inflammasome-mediated pyroptosis contributes to the pathogenesis of non-ischemic dilated cardiomyopathy.

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NLRP3 inflammasome-mediated pyroptosis contributes to the pathogenesis of non-ischemic dilated cardiomyopathy.

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