Lipopolysaccharide (LPS) Aggravates High Glucose- and Hypoxia/Reoxygenation-Induced Injury through Activating ROS-Dependent NLRP3 Inflammasome-Mediated Pyroptosis in H9C2 Cardiomyocytes.
TL;DR: LPS could increase the sensitivity of H9C2 cells to HG and H/R and aggravated HG- andH/R-induced H 9C2 cell injury by promoting ROS production to induce NLRP3 inflammasome-mediated pyroptosis.
Abstract: Diabetes aggravates myocardial ischemia-reperfusion (I/R) injury because of the combination effects of changes in glucose and lipid energy metabolism, oxidative stress, and systemic inflammatory response. Studies have indicated that myocardial I/R may coincide and interact with sepsis and inflammation. However, the role of LPS in hypoxia/reoxygenation (H/R) injury in cardiomyocytes under high glucose conditions is still unclear. Our objective was to examine whether lipopolysaccharide (LPS) could aggravate high glucose- (HG-) and hypoxia/reoxygenation- (H/R-) induced injury by upregulating ROS production to activate NLRP3 inflammasome-mediated pyroptosis in H9C2 cardiomyocytes. H9C2 cardiomyocytes were exposed to HG (30 mM) condition with or without LPS, along with caspase-1 inhibitor (Ac-YVAD-CMK), inflammasome inhibitor (BAY11-7082), ROS scavenger N-acetylcysteine (NAC), or not for 24 h, then subjected to 4 h of hypoxia followed by 2 h of reoxygenation (H/R). The cell viability, lactate dehydrogenase (LDH) release, caspase-1 activity, and intracellular ROS production were detected by using assay kits. The incidence of pyroptosis was detected by calcein-AM/propidium iodide (PI) double staining kit. The concentrations of IL-1β and IL-18 in the supernatants were assessed by ELISA. The mRNA levels of NLRP3, ASC, and caspase-1 were detected by qRT-PCR. The protein levels of NF-κB p65, NLRP3, ASC, cleaved caspase-1 (p10), IL-1β, and IL-18 were detected by western blot. The results indicated that pretreatment LPS with 1 μg/ml not 0.1 μg/ml could efficiently aggravate HG and H/R injury by activating NLRP3 inflammasome to mediate pyroptosis in H9C2 cells, as evidenced by increased LDH release and decreased cell viability in the cells, and increased expression of NLRP3, ASC, cleaved caspase-1 (p10), IL-1β, and IL-18. Meanwhile, Ac-YVAD-CMK, BAY11-7082, or NAC attenuated HG- and H/R-induced H9C2 cell injury with LPS stimulated by reversing the activation of NLRP3 inflammasome-mediated pyroptosis. In conclusion, LPS could increase the sensitivity of H9C2 cells to HG and H/R and aggravated HG- and H/R-induced H9C2 cell injury by promoting ROS production to induce NLRP3 inflammasome-mediated pyroptosis.
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Journal Article•
TL;DR: It is demonstrated that activation of caspase-1 clears intracellular bacteria in vivo independently of IL-1β and IL-18 and establishes pyroptosis as an efficient mechanism of bacterial clearance by the innate immune system.
Abstract: Macrophages mediate crucial innate immune responses via caspase-1-dependent processing and secretion of IL-1β and IL-18. While wild type Salmonella typhimurium infection is lethal to mice, a strain that persistently expresses flagellin was cleared by the cytosolic flagellin detection pathway via NLRC4 activation of caspase-1; however, this clearance was independent of IL-1β and IL-18. Instead, caspase-1 induced pyroptotic cell death released bacteria from macrophages, exposing them to uptake and killing by reactive oxygen species in neutrophils. Similarly, caspase-1 cleared Legionella and Burkholderia by cytokine independent mechanisms. Our results show, for the first time, that caspase-1 can clear intracellular bacteria in vivo independent of IL-1β and IL-18, and establish pyroptosis as an efficient mechanism of bacterial clearance by the innate immune system.
808 citations
01 Jan 2010
TL;DR: The findings of the data summarized in this review are most important for possible translation into clinical cardiology practice and possible avenues for drug development.
Abstract: Ischemia/reperfusion (I/R) injury is an inflammatory condition that is characterized by innate immunity and an adaptive immune response This review is focused on the acute inflammatory response in I/R injury, and also the adaptive immunological mechanisms in chronic ischemic disease that lead to increased vulnerability during acute events, in relation to the cell types that have been shown to mediate innate immunity to an adaptive immune response in I/R, specifically myocardial infarction Novel aspects are also highlighted in respect to the mechanisms within the cardiovascular system and cardiovascular risk factors that may be involved in the inflammatory response accompanying myocardial infarction Experimental myocardial I/R has suggested that immune cells may mediate reperfusion injury Specifically, monocytes, macrophages, T-cells, mast cells,platelets and endothelial cells are discussed with reference to the complement cascade, toll-like receptors, cytokines, oxidative stress, renin-angiotensin system, and in reference to the microvascular system in the signaling mechanisms of I/R Finally, the findings of the data summarized in this review are most important for possible translation into clinical cardiology practice and possible avenues for drug development
275 citations
TL;DR: The present state of research on targeted therapeutic drugs is elaborated upon to provide information for the treatment of sepsis and the recent development in understanding regarding the cellular pathogenesis and the target of clinical diagnosis is reviewed.
Abstract: Sepsis is defined as “a life-threatening organ dysfunction caused by a host’s dysfunctional response to infection”. Although the treatment of sepsis has developed rapidly in the past few years, sepsis incidence and mortality in clinical treatment is still climbing. Moreover, because of the diverse manifestations of sepsis, clinicians continue to face severe challenges in the diagnosis, treatment, and management of patients with sepsis. Here, we review the recent development in our understanding regarding the cellular pathogenesis and the target of clinical diagnosis of sepsis, with the goal of enhancing the current understanding of sepsis. The present state of research on targeted therapeutic drugs is also elaborated upon to provide information for the treatment of sepsis.
249 citations
TL;DR: Investigation of the effect of ferroptosis in the process of diabetes mellitus myocardial ischemia/reperfusion (I/R) injury (IRI) finds inhibition of feroptosis can alleviate DIR injury, which may provide a therapeutic regent for myocardian ischemic disease.
Abstract: Myocardial ischemic disease affects the prognosis in perioperative patients. Diabetes can aggravate myocardial injury. The purpose of this research is to investigate the effect of ferroptosis in the process of diabetes mellitus (DM) myocardial ischemia/reperfusion (I/R) injury (IRI). Endoplasmic reticulum stress (ERS) is investigated whether aggravates cardiomyocytes injury. Rat DM+I/R (DIR), cell high glucose (HG), hypoxia reoxygenation (H/R), and high-glucose H/R (HH/R) models were established. Ferroptosis inhibitor Ferrostatin-1, ferroptosis agonist Erastin, ERS inhibitor Salubrinal, and ERS agonist Tunicamycin were administered. Serum creatine kinase-MB (CK-MB), cell viability, lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), reactive oxygen species (ROS), and cellular ferrous ion concentration were examined. The level of ACSL4, GPX4, ATF4, CHOP, BCL-2, and BAX was detected. Myocardial tissue pathological change was detected by hematoxylin-eosin staining. Cardiac function was monitored by invasive hemodynamic measurements. Evans Blue-triphenyltetrazolium chloride double staining was used to detect the myocardial infarct size. In DM+sham (DS) (or HG) and I/R (or H/R) models, cardiomyocytes were injured accompanied by increased level of ferroptosis and ERS. Moreover, the cell injury was more serious in rat DIR or cell HH/R models. Inhibition of ferroptosis in DIR model could reduce ERS and myocardial injury. Inhibition of ferroptosis in H9c2 cells HG, H/R, and HH/R models could reduce cell injury. Erastin could aggravate ERS and cell injury by stimulating ferroptosis in HH/R cell model. Meanwhile, inhibition of ERS could alleviate ferroptosis and cell injury. Ferroptosis is involved in DIR injury that is related to ERS. Moreover, inhibition of ferroptosis can alleviate DIR injury, which may provide a therapeutic regent for myocardial ischemic disease.
188 citations
TL;DR: Recent advances in understanding the molecular basis for atrial fibrillation are reviewed, with a particular emphasis on relating these new insights to opportunities for clinical translation.
Abstract: Atrial fibrillation (AF) is a highly prevalent arrhythmia, with substantial associated morbidity and mortality There have been significant management advances over the past 2 decades, but the burden of the disease continues to increase and there is certainly plenty of room for improvement in treatment options A potential key to therapeutic innovation is a better understanding of underlying fundamental mechanisms This article reviews recent advances in understanding the molecular basis for AF, with a particular emphasis on relating these new insights to opportunities for clinical translation We first review the evidence relating basic electrophysiological mechanisms to the characteristics of clinical AF We then discuss the molecular control of factors leading to some of the principal determinants, including abnormalities in impulse conduction (such as tissue fibrosis and other extra-cardiomyocyte alterations, connexin dysregulation and Na+-channel dysfunction), electrical refractoriness, and impulse generation We then consider the molecular drivers of AF progression, including a range of Ca2+-dependent intracellular processes, microRNA changes, and inflammatory signaling The concept of key interactome-related nodal points is then evaluated, dealing with systems like those associated with CaMKII (Ca2+/calmodulin-dependent protein kinase-II), NLRP3 (NACHT, LRR, and PYD domains-containing protein-3), and transcription-factors like TBX5 and PitX2c We conclude with a critical discussion of therapeutic implications, knowledge gaps and future directions, dealing with such aspects as drug repurposing, biologicals, multispecific drugs, the targeting of cardiomyocyte inflammatory signaling and potential considerations in intervening at the level of interactomes and gene-regulation The area of molecular intervention for AF management presents exciting new opportunities, along with substantial challenges
185 citations
References
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TL;DR: Gasdermin D (Gsdmd) is identified by genome-wide clustered regularly interspaced palindromic repeat-Cas9 nuclease screens of caspase-11- and caspasing-1-mediated pyroptosis in mouse bone marrow macrophages to offer insight into inflammasome-mediated immunity/diseases and change the understanding of pyroPTosis and programmed necrosis.
Abstract: Inflammatory caspases (caspase-1, -4, -5 and -11) are critical for innate defences. Caspase-1 is activated by ligands of various canonical inflammasomes, and caspase-4, -5 and -11 directly recognize bacterial lipopolysaccharide, both of which trigger pyroptosis. Despite the crucial role in immunity and endotoxic shock, the mechanism for pyroptosis induction by inflammatory caspases is unknown. Here we identify gasdermin D (Gsdmd) by genome-wide clustered regularly interspaced palindromic repeat (CRISPR)-Cas9 nuclease screens of caspase-11- and caspase-1-mediated pyroptosis in mouse bone marrow macrophages. GSDMD-deficient cells resisted the induction of pyroptosis by cytosolic lipopolysaccharide and known canonical inflammasome ligands. Interleukin-1β release was also diminished in Gsdmd(-/-) cells, despite intact processing by caspase-1. Caspase-1 and caspase-4/5/11 specifically cleaved the linker between the amino-terminal gasdermin-N and carboxy-terminal gasdermin-C domains in GSDMD, which was required and sufficient for pyroptosis. The cleavage released the intramolecular inhibition on the gasdermin-N domain that showed intrinsic pyroptosis-inducing activity. Other gasdermin family members were not cleaved by inflammatory caspases but shared the autoinhibition; gain-of-function mutations in Gsdma3 that cause alopecia and skin defects disrupted the autoinhibition, allowing its gasdermin-N domain to trigger pyroptosis. These findings offer insight into inflammasome-mediated immunity/diseases and also change our understanding of pyroptosis and programmed necrosis.
3,554 citations
"Lipopolysaccharide (LPS) Aggravates..." refers background in this paper
...Studies have indicated that exogenous stimuli such as LPS and endogenous injury signals such as uric acid and ATP may induce common pathways (such as reactive oxygen species (ROS) production) to activate NLRP3 inflammasome and then trigger caspase-1-dependent pyroptosis [14, 15]....
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TL;DR: It is shown that GSDMD-NT oligomerizes in membranes to form pores that are visible by electron microscopy and kills cell-free bacteria in vitro and may have a direct bactericidal effect within the cytosol of host cells, but the importance of direct bacterial killing in controlling in vivo infection remains to be determined.
Abstract: Inflammatory caspases (caspases 1, 4, 5 and 11) are activated in response to microbial infection and danger signals. When activated, they cleave mouse and human gasdermin D (GSDMD) after Asp276 and Asp275, respectively, to generate an N-terminal cleavage product (GSDMD-NT) that triggers inflammatory death (pyroptosis) and release of inflammatory cytokines such as interleukin-1β. Cleavage removes the C-terminal fragment (GSDMD-CT), which is thought to fold back on GSDMD-NT to inhibit its activation. However, how GSDMD-NT causes cell death is unknown. Here we show that GSDMD-NT oligomerizes in membranes to form pores that are visible by electron microscopy. GSDMD-NT binds to phosphatidylinositol phosphates and phosphatidylserine (restricted to the cell membrane inner leaflet) and cardiolipin (present in the inner and outer leaflets of bacterial membranes). Mutation of four evolutionarily conserved basic residues blocks GSDMD-NT oligomerization, membrane binding, pore formation and pyroptosis. Because of its lipid-binding preferences, GSDMD-NT kills from within the cell, but does not harm neighbouring mammalian cells when it is released during pyroptosis. GSDMD-NT also kills cell-free bacteria in vitro and may have a direct bactericidal effect within the cytosol of host cells, but the importance of direct bacterial killing in controlling in vivo infection remains to be determined.
1,902 citations
"Lipopolysaccharide (LPS) Aggravates..." refers background in this paper
...Caspase-1 activation is activated by inflammasomes (including NLRP3, NLRC4, Nlrp1b, and AIM2), which cleaves pro-caspase-1 into activated caspase-1, promoting the IL-1β and IL-18 precursors to form mature IL-1β and IL-18 then mediating pyroptosis, which plays an important role in the development and maintenance of inflammatory responses [11, 12]....
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TL;DR: Current understanding of the mechanism and regulation of NLRP3 inflammasome activation as well as recent advances in the noncanonical and alternative inflammaome pathways are summarized.
1,734 citations
"Lipopolysaccharide (LPS) Aggravates..." refers background in this paper
...Caspase-1 activation is activated by inflammasomes (including NLRP3, NLRC4, Nlrp1b, and AIM2), which cleaves pro-caspase-1 into activated caspase-1, promoting the IL-1β and IL-18 precursors to form mature IL-1β and IL-18 then mediating pyroptosis, which plays an important role in the development and maintenance of inflammatory responses [11, 12]....
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...The NLRP3 inflammasome, as the mediator of inflammatory response, has been activated by both PAMPs and DAMPs, such as LPS, ATP, glucose, ROS, and crystallisation [12, 38, 39]....
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...The third pathway is that PAMPs and DAMPs promote the increase of intracellular ROS production and promote the aggregation and activation of NLRP3 inflammasome through ROS-dependent signaling pathways [12]....
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TL;DR: These results provide a unifying model for the activation of the NLRP3 inflammasome in which a drop in cytosolic K⁺ is the common step that is necessary and sufficient for caspase-1 activation.
1,498 citations
"Lipopolysaccharide (LPS) Aggravates..." refers background in this paper
...ROS acts as second messenger to drive inflammasome activation and has been identified as an important mechanism for NLRP3 inflammasome activation [47] and is believed to be a common NLR/caspase-1 complex activator, which mediates pyroptosis [48]....
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TL;DR: The authors showed that activation of caspase-1 clears intracellular bacteria in vivo independently of IL-1β and IL-18 and establishes pyroptosis as an efficient mechanism of bacterial clearance by the innate immune system.
Abstract: Macrophages mediate crucial innate immune responses via caspase-1-dependent processing and secretion of interleukin 1β (IL-1β) and IL-18. Although infection with wild-type Salmonella typhimurium is lethal to mice, we show here that a strain that persistently expresses flagellin was cleared by the cytosolic flagellin-detection pathway through the activation of caspase-1 by the NLRC4 inflammasome; however, this clearance was independent of IL-1β and IL-18. Instead, caspase-1-induced pyroptotic cell death released bacteria from macrophages and exposed the bacteria to uptake and killing by reactive oxygen species in neutrophils. Similarly, activation of caspase-1 cleared unmanipulated Legionella pneumophila and Burkholderia thailandensis by cytokine-independent mechanisms. This demonstrates that activation of caspase-1 clears intracellular bacteria in vivo independently of IL-1β and IL-18 and establishes pyroptosis as an efficient mechanism of bacterial clearance by the innate immune system.
1,022 citations