scholarly journals Vibrio pore-forming leukocidin activates pyroptotic cell death via the NLRP3 inflammasome

2019 ◽  
Author(s):  
Noam Baram ◽  
Hadar Cohen ◽  
Liat Edry-Botzer ◽  
Dor Salomon ◽  
Motti Gerlic
Keyword(s):  
Cell Death ◽  
Nlrp3 Inflammasome ◽  
Host Cells ◽  
Inflammasome Activation ◽  
Vibrio Proteolyticus ◽  
Caspase 1 ◽  
Cell Plasma ◽  
Target Membrane ◽  
Cell Death Mechanisms ◽  
Different Diameters

ABSTRACTCell death mechanisms are central to combat infectious microbes and to drive pathological inflammation. One such mechanism, the inflammasome, controls infection through either activation of caspase-1 and the subsequent secretion of the mature pro-inflammatory cytokine, interleukin 1β (IL-1β), or by stopping the dissemination of intracellular pathogens by inducing pyroptotic cell death in infected cells. Hemolysins, which are pore-forming toxins (PFTs), target the host cell plasma membrane by producing pores with different diameters. These pores alter the permeability of the target membrane, often leading to cell death. We previously discovered a functional and potent pore-forming, leukocidin domain-containing hemolysin produced by the Gram-negative marine bacterium Vibrio proteolyticus (V. proteolyticus), termed VPRH. Although leukocidin domains are found in other known PFTs, VPRH constitutes a distinct, understudied class within the leukocidin superfamily. Since PTFs of other pathogens were shown to induce cell death by activating the inflammasome pathway, we hypothesized that VPRH-induced cell death is mediated by direct activation of the inflammasome in mammalian immune host cells. Indeed, we found that VPRH induced a two-step cell death in primary macrophages. The first, a rapid step, was mediated by activating the NLRP3 inflammasome, leading to caspase-1 activation and GSDMD cleavage that resulted in IL-1β secretion and pyroptotic cell death. The second step was independent of the inflammasome; however, its mechanism remains unknown. This study sets the foundation for better understanding the immunological consequences of inflammasome activation by a new leukocidin class of toxins.

scholarly journals Oxidative metabolism enables Salmonella evasion of the NLRP3 inflammasome

2014 ◽  
Vol 211 (4) ◽  
pp. 653-668 ◽  
Author(s):  
Meghan A. Wynosky-Dolfi ◽  
Annelise G. Snyder ◽  
Naomi H. Philip ◽  
Patrick J. Doonan ◽  
Maya C. Poffenberger ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Oxidative Metabolism ◽  
Citrate Synthase ◽  
Elevated Serum ◽  
Systemic Infection ◽  
Host Cells ◽  
Inflammasome Activation ◽  
Microbial Infection ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

Microbial infection triggers assembly of inflammasome complexes that promote caspase-1–dependent antimicrobial responses. Inflammasome assembly is mediated by members of the nucleotide binding domain leucine-rich repeat (NLR) protein family that respond to cytosolic bacterial products or disruption of cellular processes. Flagellin injected into host cells by invading Salmonella induces inflammasome activation through NLRC4, whereas NLRP3 is required for inflammasome activation in response to multiple stimuli, including microbial infection, tissue damage, and metabolic dysregulation, through mechanisms that remain poorly understood. During systemic infection, Salmonella avoids NLRC4 inflammasome activation by down-regulating flagellin expression. Macrophages exhibit delayed NLRP3 inflammasome activation after Salmonella infection, suggesting that Salmonella may evade or prevent the rapid activation of the NLRP3 inflammasome. We therefore screened a Salmonella Typhimurium transposon library to identify bacterial factors that limit NLRP3 inflammasome activation. Surprisingly, absence of the Salmonella TCA enzyme aconitase induced rapid NLRP3 inflammasome activation. This inflammasome activation correlated with elevated levels of bacterial citrate, and required mitochondrial reactive oxygen species and bacterial citrate synthase. Importantly, Salmonella lacking aconitase displayed NLRP3- and caspase-1/11–dependent attenuation of virulence, and induced elevated serum IL-18 in wild-type mice. Together, our data link Salmonella genes controlling oxidative metabolism to inflammasome activation and suggest that NLRP3 inflammasome evasion promotes systemic Salmonella virulence.

scholarly journals FRI0001 NEUTROPHILS IN GRANULOMATOSIS WITH POLYANGIITIS DISPLAY FEATURES OF PYROPTOSIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 572.2-572
Author(s):  
A. Kerstein-Staehle ◽  
N. Leinung ◽  
J. Meyer ◽  
S. Pitann ◽  
A. Müller ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Cell Death ◽  
Nlrp3 Inflammasome ◽  
Peripheral Blood ◽  
Granulomatosis With Polyangiitis ◽  
Granulomatous Inflammation ◽  
Clinical Aspects ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
Active Caspase

Background:Granulomatosis with polyangiitis (GPA) is characterized by extravascular necrotizing granulomatous inflammation and systemic ANCA – associated (AAV) vasculitis with neutrophils as a key player in the pathogenesis (1). We and others have shown that neutrophil-related cell death mechanisms contribute to chronic inflammatory processes in AAV (2, 3). Recently, another form of inflammatory cell death primarily described in monocytes called pyroptosis was also discovered in neutrophils (4). A cardinal feature of pyroptosis is the activation of the NLRP3 inflammasome, a sensor of different pathogen- and damage-associated molecular patterns (PAMP, DAMP), following caspase-1-mediated processing and secretion of IL-1beta (5).Objectives:The aim of this study was to investigate, if neutrophils from GPA patients express pyroptosis-related components NLRP3, active caspase 1 and cleaved IL-1beta.Methods:Polymorphonuclear leukocytes (PMN) were isolated from peripheral blood of GPA patients and healthy controls (HC) (n = 10 each). Expression of NLRP3, inactive/active caspase 1 and active IL-1beta was determined by western blot. In addition, peripheral blood mononuclear cells (PBMC) were isolated from GPA and HC. mRNA expression ofnlrp3andil1bwas determined by qPCR. To exclude false-positive results by contamination with monocytes we performed flow cytometry analysis of whole blood samples with markers CD3, CD14, CD15, CD66b and NLRP3.Results:PMN from GPA patients showed markedly increased expression of NLRP3, active caspase 1 and active IL-1beta compared to HC. In contrast, there was no difference between GPA and HC on the mRNA level of neithernlrp3noril1bin PBMC. In addition, we confirmed by flow cytometry increased expression of NLRP3 in PMN from GPA, but not in monocytes.Conclusion:Here we provide evidence, that neutrophils from GPA undergo pyroptosis, demonstrated by increased NLRP3, active caspase 1 expression as well as IL-1beta processing. Neutrophils are present in high numbers at the site of granulomatous lesions of inflamed tissue in GPA and IL-1beta is increased in GPA sera (2). Therefore, neutrophils represent a potential source of IL-1beta in GPA. Given the fact that GPA-associated features such as massive release of necrosis-related DAMP or microbial agents such asStaphylococcus aureus(6) can activate the NLRP3-inflammasome, we identified here a potential relevant mechanism of neutrophils contributing to chronic inflammation of GPA.References:[1]Jennette, J.C., and Falk, R.J. (2014). Pathogenesis of antineutrophil cytoplasmic autoantibody-mediated disease. Nat. Rev. Rheumatol.10, 463–473.[2]Millet, A., Martin, K.R., Bonnefoy, F., Saas, P., Mocek, J., Alkan, M., Terrier, B.,Kerstein,A., Tamassia, N., Satyanarayanan, S.K., et al. (2015). Proteinase 3 on apoptotic cells disrupts immune silencing in autoimmune vasculitis. J. Clin. Invest. 125, 4107–4121.[3]Schreiber, A., Rousselle, A., Becker, J.U., von Mässenhausen, A., Linkermann, A., and Kettritz, R. (2017). Necroptosis controls NET generation and mediates complement activation, endothelial damage, and autoimmune vasculitis. Proc. Natl. Acad. Sci. 201708247.[4]Tourneur, L., and Witko-Sarsat, V. (2019). Inflammasome activation: Neutrophils go their own way. J. Leukoc. Biol.105, 433–436.[5]Bergsbaken, T., Fink, S.L., and Cookson, B.T. (2009). Pyroptosis: Host cell death and inflammation. Nat. Rev. Microbiol.7, 99–109.[6]Lamprecht, P.,Kerstein, A., Klapa, S., Schinke, S., Karsten, C.M., Yu, X., Ehlers, M., Epplen, J.T., Holl-Ulrich, K., Wiech, T., et al. (2018). Pathogenetic and Clinical Aspects of Anti-Neutrophil Cytoplasmic Autoantibody-Associated Vasculitides. Front. Immunol.9, 1–10.Disclosure of Interests:Anja Kerstein-Staehle: None declared, Nadja Leinung: None declared, Jannik Meyer: None declared, Silke Pitann: None declared, Antje Müller: None declared, Gabriela Riemekasten Consultant of: Cell Trend GmbH, Janssen, Actelion, Boehringer Ingelheim, Speakers bureau: Actelion, Novartis, Janssen, Roche, GlaxoSmithKline, Boehringer Ingelheim, Pfizer, Peter Lamprecht: None declared

scholarly journals Trichomonas vaginalis Induces NLRP3 Inflammasome Activation and Pyroptotic Cell Death in Human Macrophages

2018 ◽  
Vol 11 (1) ◽  
pp. 86-98 ◽  
Author(s):  
Angelica Montenegro Riestra ◽  
J. Andrés Valderrama ◽  
Kathryn A. Patras ◽  
Sharon D. Booth ◽  
Xing Yen Quek ◽  
...  
Keyword(s):  
Cell Death ◽  
Host Cell ◽  
Nlrp3 Inflammasome ◽  
Trichomonas Vaginalis ◽  
Inflammasome Activation ◽  
Cell Detection ◽  
Human Macrophages ◽  
Sexually Transmitted ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

Trichomonas vaginalis is a sexually transmitted, eukaryotic parasite that causes trichomoniasis, the most common nonviral, sexually transmitted disease in the USA and worldwide. Little is known about the molecular mechanisms involved in the host immune response to this widespread parasite. Here we report that T. vaginalis induces NLRP3 inflammasome activation in human macrophages, leading to caspase-1 activation and the processing of pro-IL-1β to the mature and bioactive form of the cytokine. Using inhibitor-based approaches, we show that NLRP3 activation by T. vaginalis involves host cell detection of extracellular ATP via P2X7 receptors and potassium efflux. In addition, our data reveal that T. vaginalis inflammasome activation induces macrophage inflammatory cell death by pyroptosis, known to occur via caspase-1 cleavage of the gasdermin D protein, which assembles to form pores in the host cell membrane. We found that T. vaginalis-induced cytolysis of macrophages is attenuated in gasdermin D knockout cells. Lastly, in a murine challenge model, we detected IL-1β production in vaginal fluids in response to T. vaginalis infection in vivo. Together, our findings mechanistically dissect how T. vaginalis contributes to the production of the proinflammatory IL-1β cytokine and uncover pyroptosis as a mechanism by which the parasite can trigger host macrophage cell death.

scholarly journals Lycopus lucidus Turcz exerts neuroprotective effect against H2O2‑induced neuroinflammation by inhibiting NLRP3 inflammasome activation in cortical neurons

2021 ◽  
Author(s):  
Hyunseong Kim ◽  
Jin Young Hong ◽  
Wan-Jin Jeon ◽  
Junseon Lee ◽  
Seung Ho Baek ◽  
...  
Keyword(s):  
Cell Death ◽  
Nlrp3 Inflammasome ◽  
Cortical Neurons ◽  
Neuronal Damage ◽  
Neuroprotective Effect ◽  
Synaptic Connectivity ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation ◽  
Rat Cortical Neurons

Abstract Background Central nervous system (CNS) injuries are a leading cause of permanent functional impairment in humans. Nerve damage can be aggravated by neuroinflammation mediated by protein complexes known as inflammasomes, such as the NLRP3 inflammasome which is a key mediator of caspase-1 and interleukin-1β (IL-1β) /interleukin-18 (IL-18) activation. Lycopus lucidus Turcz (LLT) is a traditional medicinal herb that exerts therapeutic effects against oxidative stress, inflammation, and angiogenesis; however, it remains unclear whether LLT can directly protect neurons against damage, and the underlying molecular mechanisms are poorly understood. Methods We investigated the neuroprotective effect of LLT against hydrogen peroxide (H2O2)-induced neuronal damage in cultured primary rat cortical neurons, as well as the potential underlying mechanisms. Neuronal viability and cell death assays were used to determine the effects of LLT on neuroprotection, while the mode of cell death was confirmed using flow cytometry. Changes in the expression of inflammatory factors involved in activation of the NLRP3 inflammasome were measured using immunocytochemistry (ICC) and confirmed by real-time PCR. And, we analyzed that the effect of LLT on neurotrophic factors secretion and synaptic connectivity using ICC in H2O2-induced neuron at 7 days in vitro. Results LLT effectively protected cultured rat cortical neurons from H2O2-induced injury by significantly inhibiting NLRP3 inflammasome activation. In addition, LLT significantly reduced caspase1 activation, which is known to be induced by inflammasome formation, and consequently regulated the secretion of IL-1β/IL-18. We demonstrated that LLT enhances axonal elongation and synaptic connectivity against H2O2-induced injury of rat primary cortical neuron. Conclusions Together, these results demonstrate that LLT can directly protect cultured cortical neurons from H2O2-induced neuronal damage by inhibiting NLRP3 inflammasome activation and the secretion of caspase-1 and IL-1β/IL-18. Thus, our study provides new insights into the therapeutic mechanisms of LLT and suggests that the NLRP3 inflammasome could be a promising target for treating neurological diseases.

Using tissue microarray to detect inflammasome signaling components that contribute to the pathogenesis of myelodysplastic syndrome.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 7044-7044
Author(s):  
Tony Kurian ◽  
Kathy L. McGraw ◽  
Sanjay Bridgelall ◽  
Rohit Sharma ◽  
Jeffrey E. Lancet ◽  
...  
Keyword(s):  
Cell Death ◽  
Tissue Microarray ◽  
Nlrp3 Inflammasome ◽  
Expression Patterns ◽  
Low Risk ◽  
Inflammasome Activation ◽  
Beta Catenin ◽  
Spearman Correlation ◽  
Caspase 1 ◽  
Blast Count

7044 Background: Myelodysplastic syndromes (MDS) are characterized by aberrant maturation, ineffective hematopoiesis, cytopenia, and progression to acute myeloid leukemia. MDS pathogenesis is multifactorial and potentially linked to constitutive innate immune stimulation converging upon the NLRP3 inflammasome to induce pyroptosis, a caspase-1 dependent cell death. Inflammasome assembly is initiated by both cell-extrinsic stimuli including S100A9, the TLR4 and CD33 ligand, and cell-intrinsic danger signals licensing caspase-1 which activates IL1b and beta-catenin resulting in cell death and cellular proliferation leading to maturation and differentiation blocks. Further, EYA2 has been suggested to be an inflammasome activator, whereas cPLA2 has been suggested to be an inhibitor. The purpose of this study is to determine whether immunohistochemistry (IHC) may be utilized to assess expression of inflammasome components. Methods: An IRB protocol was approved prior to initiating this study. We retrospectively identified 43 low risk MDS patients. A tissue microarray (TMA) was constructed utilizing MDS bone marrow biopsy samples (2-3 representative cores per sample). IL-1, S100A9, EYA2, cPLA2, beta-catenin, and TLR4 expression were assessed by IHC after validation of each antibody. IHC expression was scored independently by two hematopathologists by calculating scores (product of staining intensity x percent expression). IHC expression was compared using Spearman correlation estimate. Demographic and clinical data were collected and correlated with IHC expression using Kruskal-Wallis test, Spearman correlation, and Logrank test. Results: Patients were median 72 years of age, 67% men and included 47% MDS-MLD, 35% MDS-RS, 14% MDS-SLD, 2% MDS del5q and 2% MDS-U. IL-1 expression correlated with beta-catenin expression, r = 0.42, 95% CI 0.115 to 0.658 (p = 0.007). There was a trend towards significance between IL-1 and cPLA2, r = 0.30 (p = 0.067); S100A9 and cPLA2, r = 0.31 (p = 0.052); and S100A9 and EYA2, r = 0.31 (p = 0.057). Percentage EYA2 expression correlated with blast count, r = 0.425 (p = 0.008). The IHC expression of these antigens did not correlate with WHO MDS subclassification, IPSS, R-IPSS, disease progression, or survival (p > 0.05). Conclusions: IHC staining of inflammasome activators using TMA may allow better characterization of molecular pathways contributing the MDS pathogenesis. A correlation was seen between expression of antigens known to be increased downstream of NLRP3 inflammasome activation. Furthermore, increased expression of EYA2 correlated with blast count. A future study will compare expression patterns between normal, low risk MDS and high risk MDS samples and correlate these findings with clinical outcome data to further elucidate the pathogenesis of MDS and identify potential targetable markers for novel therapeutic strategies.

scholarly journals Dimethyl Fumarate Alleviates NLRP3 Inflammasome Activation in Microglia and Sickness Behavior in LPS-Challenged Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Bora Tastan ◽  
Burak I. Arioz ◽  
Kemal Ugur Tufekci ◽  
Emre Tarakcioglu ◽  
Ceren Perihan Gonul ◽  
...  
Keyword(s):  
Cell Death ◽  
Nlrp3 Inflammasome ◽  
Forced Swim Test ◽  
Sickness Behavior ◽  
Dimethyl Fumarate ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

NLRP3 inflammasome activation contributes to several pathogenic conditions, including lipopolysaccharide (LPS)-induced sickness behavior characterized by reduced mobility and depressive behaviors. Dimethyl fumarate (DMF) is an immunomodulatory and anti-oxidative molecule commonly used for the symptomatic treatment of multiple sclerosis and psoriasis. In this study, we investigated the potential use of DMF against microglial NLRP3 inflammasome activation both in vitro and in vivo. For in vitro studies, LPS- and ATP-stimulated N9 microglial cells were used to induce NLRP3 inflammasome activation. DMF’s effects on inflammasome markers, pyroptotic cell death, ROS formation, and Nrf2/NF-κB pathways were assessed. For in vivo studies, 12–14 weeks-old male BALB/c mice were treated with LPS, DMF + LPS and ML385 + DMF + LPS. Behavioral tests including open field, forced swim test, and tail suspension test were carried out to see changes in lipopolysaccharide-induced sickness behavior. Furthermore, NLRP3 and Caspase-1 expression in isolated microglia were determined by immunostaining. Here we demonstrated that DMF ameliorated LPS and ATP-induced NLRP3 inflammasome activation by reducing IL-1β, IL-18, caspase-1, and NLRP3 levels, reactive oxygen species formation and damage, and inhibiting pyroptotic cell death in N9 murine microglia via Nrf2/NF-κB pathways. DMF also improved LPS-induced sickness behavior in male mice and decreased caspase-1/NLRP3 levels via Nrf2 activation. Additionally, we showed that DMF pretreatment decreased miR-146a and miR-155 both in vivo and in vitro. Our results proved the effectiveness of DMF on the amelioration of microglial NLRP3 inflammasome activation. We anticipate that this study will provide the foundation consideration for further studies aiming to suppress NLRP3 inflammasome activation associated with in many diseases and a better understanding of its underlying mechanisms.

scholarly journals Chlamydia muridarumInfection of Macrophages Stimulates IL-1βSecretion and Cell Death via Activation of Caspase-1 in an RIP3-Independent Manner

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Lixiang Chen ◽  
Xue Liu ◽  
Xin Yu ◽  
Rongrong Ren ◽  
Chao Wang ◽  
...  
Keyword(s):  
Cell Death ◽  
Innate Immune ◽  
Host Cells ◽  
Inflammasome Activation ◽  
Gram Negative Bacteria ◽  
Independent Manner ◽  
Chlamydia Muridarum ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

Chlamydiae are Gram-negative bacteria, which replicate exclusively in the infected host cells. Infection of the host cells by Chlamydiae stimulates the innate immune system leading to an inflammatory response, which is manifested not only by secretion of proinflammatory cytokines such as IL-1βfrom monocytes, macrophages, and dendritic cells, but also possibly by cell death mediated by Caspase-1 pyroptosis. RIP3 is a molecular switch that determines the development of necrosis or inflammation. However, the involvement of RIP3 in inflammasome activation byChlamydia muridaruminfection has not been clarified. Here, we assessed the role of RIP3 in synergy with Caspase-1 in the induction of IL-1βproduction in BMDM after either LPS/ATP orChlamydia muridarumstimulation. The possibility of pyroptosis and necroptosis interplays and the role of RIP3 in IL-1βproduction duringChlamydia muridaruminfection in BMDM was investigated as well. The data indicated that RIP3 is involved in NLRP3 inflammasome activation in LPS/ATP-stimulated BMDMs but not inChlamydia muridaruminfection. Pyroptosis occurred in BMDM after LPS/ATP stimulation orChlamydia muridaruminfection. Moreover, the results also illuminated the important role of the Caspase-1-mediated pyroptosis process which does not involve RIP3. Taken together, these observations may help shed new light on details in inflammatory signaling pathways activated byChlamydia muridaruminfection.

scholarly journals Haemophilus ducreyi Infection Induces Activation of the NLRP3 Inflammasome in Nonpolarized but Not in Polarized Human Macrophages

2013 ◽  
Vol 81 (8) ◽  
pp. 2997-3008 ◽  
Author(s):  
Wei Li ◽  
Barry P. Katz ◽  
Margaret E. Bauer ◽  
Stanley M. Spinola
Keyword(s):  
Nlrp3 Inflammasome ◽  
Interleukin 1 ◽  
Study Data ◽  
Human Infection ◽  
Haemophilus Ducreyi ◽  
Inflammasome Activation ◽  
Microbial Infection ◽  
Content Type ◽  
Ulcer Disease ◽  
Caspase 1

ABSTRACTRecognition of microbial infection by certain intracellular pattern recognition receptors leads to the formation of a multiprotein complex termed the inflammasome. Inflammasome assembly activates caspase-1 and leads to cleavage and secretion of the proinflammatory cytokines interleukin-1 beta (IL-1β) and IL-18, which help control many bacterial pathogens. However, excessive inflammation mediated by inflammasome activation can also contribute to immunopathology. Here, we investigated whetherHaemophilus ducreyi, a Gram-negative bacterium that causes the genital ulcer disease chancroid, activates inflammasomes in experimentally infected human skin and in monocyte-derived macrophages (MDM). AlthoughH. ducreyiis predominantly extracellular during human infection, several inflammasome-related components were transcriptionally upregulated inH. ducreyi-infected skin. Infection of MDM with live, but not heat-killed,H. ducreyiinduced caspase-1- and caspase-5-dependent processing and secretion of IL-1β. Blockage ofH. ducreyiuptake by cytochalasin D significantly reduced the amount of secreted IL-1β. Knocking down the expression of the inflammasome components NLRP3 and ASC abolished IL-1β production. Consistent with NLRP3-dependent inflammasome activation, blocking ATP signaling, K+efflux, cathepsin B activity, and lysosomal acidification all inhibited IL-1β secretion. However, inhibition of the production and function of reactive oxygen species did not decrease IL-1β production. Polarization of macrophages to classically activated M1 or alternatively activated M2 cells abrogated IL-1β secretion elicited byH. ducreyi. Our study data indicate thatH. ducreyiinduces NLRP3 inflammasome activation via multiple mechanisms and suggest that the heterogeneity of macrophages within human lesions may modulate inflammasome activation during human infection.

Sign in / Sign up

Export Citation Format

Share Document