scholarly journals ADP-Ribosylation of NLRP3 by Mycoplasma pneumoniae CARDS Toxin Regulates Inflammasome Activity

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Santanu Bose ◽  
Jesus A. Segovia ◽  
Sudha R. Somarajan ◽  
Te-Hung Chang ◽  
T. R. Kannan ◽  
...  
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Proinflammatory Cytokines ◽  
Nlrp3 Inflammasome ◽  
Inflammasome Activation ◽  
Content Type ◽  
Adp Ribosylation ◽  
Protein Toxin ◽  
Nlrp3 Inflammasome Activation ◽  
Adp Ribosyltransferase ◽  
Cards Toxin

ABSTRACTThe inflammasome is a major regulator of inflammation through its activation of procaspase-1, which cleaves prointerleukin-1β (pro-IL-1β) into its mature form. IL-1β is a critical proinflammatory cytokine that dictates the severity of inflammation associated with a wide spectrum of inflammatory diseases. NLRP3 is a key component of the inflammasome complex, and multiple signals and stimuli trigger formation of the NLRP3 inflammasome complex. In the current study, we uncovered a yet unknown mechanism of NLRP3 inflammasome activation by a pathogen-derived factor. We show that the unique bacterial ADP-ribosylating and vacuolating toxin produced byMycoplasma pneumoniaeand designated community-acquired respiratory distress syndrome (CARDS) toxin activates the NLRP3 inflammasome by colocalizing with the NLRP3 inflammasome and catalyzing the ADP-ribosylation of NLRP3. Mutant full-length CARDS toxin lacking ADP-ribosyltransferase (ADPRT) activity and truncated CARDS toxins unable to bind to macrophages and be internalized failed to activate the NLRP3 inflammasome. These studies demonstrate that CARDS toxin-mediated ADP-ribosylation constitutes an important posttranslational modification of NLRP3, that ADPRT activity of CARDS toxin is essential for NLRP3 inflammasome activation, and that posttranslational ADPRT-mediated modification of the inflammasome is a newly discovered mechanism for inflammasome activation with subsequent release of IL-1β and associated pathologies.IMPORTANCEInflammation is a fundamental innate immune response to environmental factors, including infections. The inflammasome represents a multiprotein complex that regulates inflammation via its ability to activate specific proinflammatory cytokines, resulting in an effective host protective response. However, excessive release of proinflammatory cytokines can occur following infection that skews the host response to “hyperinflammation” with exaggerated tissue damage.Mycoplasma pneumoniae, a common bacterial airway pathogen, possesses a unique protein toxin with ADP-ribosyltransferase and vacuolating properties capable of reproducing the robust inflammation and cytopathology associated with mycoplasma infection. Here, we show that the toxin uniquely activates the NLRP3 inflammasome by colocalizing with and ADP-ribosylating NLRP3, possibly leading to “hyperinflammation” and thus uncovering a novel target for therapeutic intervention.

Mycoplasma Pneumoniae Cards Toxin Regulates NLRP3 Inflammasome Activation

2015 ◽  
Vol 135 (2) ◽  
pp. AB153
Author(s):  
Jesus A. Segovia ◽  
Santanu Bose ◽  
Sudha R. Somarajan ◽  
Te-Hung Chang ◽  
Thirumalai Kannan ◽  
...  
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Nlrp3 Inflammasome ◽  
Inflammasome Activation ◽  
Nlrp3 Inflammasome Activation ◽  
Cards Toxin

scholarly journals The Synthetic Lignan Secoisolariciresinol Diglucoside Prevents Asbestos-Induced NLRP3 Inflammasome Activation in Murine Macrophages

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Ralph A. Pietrofesa ◽  
Patrick Woodruff ◽  
Wei-Ting Hwang ◽  
Priyal Patel ◽  
Shampa Chatterjee ◽  
...  
Keyword(s):  
Proinflammatory Cytokines ◽  
Nlrp3 Inflammasome ◽  
Nitrosative Stress ◽  
Antioxidant Properties ◽  
Peritoneal Macrophages ◽  
Inflammasome Activation ◽  
Secoisolariciresinol Diglucoside ◽  
Nlrp3 Inflammasome Activation ◽  
Acute And Chronic Inflammation ◽  
Nlrp3 Expression

Background. The interaction of asbestos with macrophages drives two key processes that are linked to malignancy: (1) the generation of reactive oxygen species (ROS)/reactive nitrogen species (RNS) and (2) the activation of an inflammation cascade that drives acute and chronic inflammation, with the NLRP3 inflammasome playing a key role. Synthetic secoisolariciresinol diglucoside (SDG), LGM2605, is a nontoxic lignan with anti-inflammatory and antioxidant properties and was evaluated for protection from asbestos in murine peritoneal macrophages (MF).Methods. MFs were exposed to crocidolite asbestos ± LGM2605 given 4 hours prior to exposure and evaluated at various times for NLRP3 expression, secretion of inflammasome-activated cytokines (IL-1βand IL-18), proinflammatory cytokines (IL-6, TNFα, and HMGB1), NF-κB activation, and levels of total nitrates/nitrites.Results. Asbestos induces a significant (p<0.0001) increase in the NLRP3 subunit, release of proinflammatory cytokines, NLRP3-activated cytokines, NF-κB, and levels of nitrates/nitrites. LGM2605 significantly reduced NLRP3 ranging from 40 to 81%, IL-1βby 89–96%, and TNFαby 67–78%, as well as activated NF-κB by 48-49% while decreasing levels of nitrates/nitrites by 85–93%.Conclusions. LGM2605 reduced asbestos-induced NLRP3 expression, proinflammatory cytokine release, NF-κB activation, and nitrosative stress in MFs supporting its possible use in preventing the asbestos-induced inflammatory cascade leading to malignancy.

scholarly journals Modulation of RAS and PI3-AKT pathway by Stavudine (d4T) in PBMC of Alzheimer’s Disease Patients

2020 ◽  
Author(s):  
Francesca La Rosa ◽  
Chiara Paola Zoia ◽  
Chiara Bazzini ◽  
Alessandra Bolognini ◽  
Saresella Marina ◽  
...  
Keyword(s):  
Proinflammatory Cytokines ◽  
Nlrp3 Inflammasome ◽  
Molecular Mechanisms ◽  
Beclin 1 ◽  
Enzyme Linked Immunosorbent Assay ◽  
Inflammasome Activation ◽  
Beneficial Effects ◽  
Nlrp3 Inflammasome Activation ◽  
Chaperone Mediated Autophagy ◽  
Inflammasome Activity

Abstract Background Aβ42-deposition plays a pivotal role in AD-pathogenesis by inducing the activation of microglial cells and neuroinflammation. This process is antagonized by microglia-mediated clearance of Aβ plaques. Activation of the NLRP3 inflammasome is involved in neuroinflammation and in the impairments of Aβ-plaques clearance. Stavudine (d4T) on the other hand down-regulates the NLRP3 inflammasome and stimulates autophagy-mediated Aβ-clearing in a TPH-1 cell line model. Methods We explored the effect of d4T on Aβ- autophagy using PBMC of AD patients that were primed with LPS and stimulated with Aβ in the absence/presence of d4T. We analyzed the NLRP3 inflammasome activity by measuring NLRP3-ASC complexes formation by AMNIS Flow-sight and pro-inflammatory cytokines (IL-1β, IL-18 and Caspase-1) production by enzyme-linked immunosorbent assay (ELISA). Western blot analyses were used to measure phosphorylation and protein expression of p38, CREB, ERK and AKT, p70, LAMP 2A, beclin-1 and Bax. Results data showed that d4T: 1) down regulates NLRP3 inflammasome activation and the production of down-stream proinflammatory cytokines even in PBMC; 2) stimulates the phosphorylation of AKT, ERK, p70 as well as LAMP2A production, but does modulate beclin-1, suggesting a selective effect of this compound on chaperone-mediated autophagy (CMA); 3) up regulates p-CREB and BAX, possibly diminishing Aβ–mediated cytotoxicity; and 4) reduces the phosphorylation of p-38, a protein involved in the production of proinflammatory cytokines. Conclusions d4T reduces the activation of the NLRP3 inflammasome and stimulates CMA autophagy as well as molecular mechanisms that modulate cytotoxicity and reduce inflammation in cells of AD patients. It might be interesting to verify the possibly beneficial effects of d4T in the clinical scenario.

scholarly journals Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Activates the NLRP3 Inflammasome in Human Macrophages, Leading to the Release of Proinflammatory Cytokines

2015 ◽  
Vol 83 (4) ◽  
pp. 1487-1496 ◽  
Author(s):  
Bruce J. Shenker ◽  
David M. Ojcius ◽  
Lisa P. Walker ◽  
Ali Zekavat ◽  
Monika Damek Scuron ◽  
...  
Keyword(s):  
Proinflammatory Cytokines ◽  
Nlrp3 Inflammasome ◽  
Purinergic Receptor ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Extracellular Atp ◽  
Ros Generation ◽  
Inflammasome Activation ◽  
Cytolethal Distending Toxin ◽  
Content Type ◽  
Atp Levels

The cytolethal distending toxin (Cdt) is produced from a number of bacteria capable of causing infection and inflammatory disease. Our previous studies withActinobacillus actinomycetemcomitansCdt demonstrate not only that the active toxin subunit functions as a phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase but also that macrophages exposed to the toxin were stimulated to produce proinflammatory cytokines. We now demonstrate that the Cdt-induced proinflammatory response involves the activation of the NLRP3 inflammasome. Specific inhibitors and short hairpin RNA (shRNA) were employed to demonstrate requirements for NLRP3 and ASC as well as caspase-1. Furthermore, Cdt-mediated inflammasome activation is dependent upon upstream signals, including reactive oxygen species (ROS) generation and Cdt-induced increases in extracellular ATP levels. Increases in extracellular ATP levels contribute to the activation of the P2X7purinergic receptor, leading to K+efflux. The relationship between the abilities of the active toxin subunit CdtB to function as a lipid phosphatase, activate the NLRP3 inflammasome, and induce a proinflammatory cytokine response is discussed. These studies provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms such asAggregatibacter actinomycetemcomitans.

scholarly journals Lactobacillus rhamnosus GR-1 Ameliorates Escherichia coli-Induced Inflammation and Cell Damage via Attenuation of ASC-Independent NLRP3 Inflammasome Activation

2015 ◽  
Vol 82 (4) ◽  
pp. 1173-1182 ◽  
Author(s):  
Qiong Wu ◽  
Ming-Chao Liu ◽  
Jun Yang ◽  
Jiu-Feng Wang ◽  
Yao-Hong Zhu
Keyword(s):  
Escherichia Coli ◽  
Mrna Expression ◽  
Nlrp3 Inflammasome ◽  
Cell Damage ◽  
Lactobacillus Rhamnosus ◽  
Adaptor Protein ◽  
Inflammasome Activation ◽  
Content Type ◽  
E Coli ◽  
Nlrp3 Inflammasome Activation

ABSTRACTEscherichia coliis a major environmental pathogen causing bovine mastitis, which leads to mammary tissue damage and cell death. We explored the effects of the probioticLactobacillus rhamnosusGR-1 on amelioratingE. coli-induced inflammation and cell damage in primary bovine mammary epithelial cells (BMECs). Increased Toll-like receptor 4 (TLR4), NOD1, and NOD2 mRNA expression was observed followingE. colichallenge, but this increase was attenuated byL. rhamnosusGR-1 pretreatment. Immunofluorescence and Western blot analyses revealed thatL. rhamnosusGR-1 pretreatment decreased theE. coli-induced increases in the expression of the NOD-like receptor family member pyrin domain-containing protein 3 (NLRP3) and the serine protease caspase 1. However, expression of the adaptor protein apoptosis-associated speck-like protein (ASC, encoded by thePycardgene) was decreased duringE. coliinfection, even withL. rhamnosusGR-1 pretreatment. Pretreatment withL. rhamnosusGR-1 counteracted theE. coli-induced increases in interleukin-1β (IL-1β), -6, -8, and -18 and tumor necrosis factor alpha mRNA expression but upregulated IL-10 mRNA expression. Our data indicate thatL. rhamnosusGR-1 reduces the adhesion ofE. colito BMECs, subsequently amelioratingE. coli-induced disruption of cellular morphology and ultrastructure and limiting detrimental inflammatory responses, partly via promoting TLR2 and NOD1 synergism and attenuating ASC-independent NLRP3 inflammasome activation. Although the residual pathogenic activity ofL. rhamnosus, the dosage regimen, and the means of probiotic supplementation in cattle remain undefined, our data enhance our understanding of the mechanism of action of this candidate probiotic, allowing for development of specific probiotic-based therapies and strategies for preventing pathogenic infection of the bovine mammary gland.

scholarly journals Capsular Polysaccharide Is Involved in NLRP3 Inflammasome Activation by Klebsiella pneumoniae Serotype K1

2015 ◽  
Vol 83 (9) ◽  
pp. 3396-3409 ◽  
Author(s):  
Kuo-Feng Hua ◽  
Feng-Ling Yang ◽  
Hsiao-Wen Chiu ◽  
Ju-Ching Chou ◽  
Wei-Chih Dong ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Nlrp3 Inflammasome ◽  
Capsular Polysaccharide ◽  
Pyogenic Liver Abscess ◽  
Mitogen Activated Protein Kinase ◽  
Ros Generation ◽  
Inflammasome Activation ◽  
Dependent Manner ◽  
Content Type ◽  
Nlrp3 Inflammasome Activation

Klebsiella pneumoniae(strain 43816, K2 serotype) induces interleukin-1β (IL-1β) secretion, but neither the bacterial factor triggering the activation of these inflammasome-dependent responses nor whether they are mediated by NLRP3 or NLRC4 is known. In this study, we identified a capsular polysaccharide (K1-CPS) inK. pneumoniae(NTUH-K2044, K1 serotype), isolated from a primary pyogenic liver abscess (PLAK. pneumoniae), as theKlebsiellafactor that induces IL-1β secretion in an NLRP3-, ASC-, and caspase-1-dependent manner in macrophages. K1-CPS induced NLRP3 inflammasome activation through reactive oxygen species (ROS) generation, mitogen-activated protein kinase phosphorylation, and NF-κB activation. Inhibition of both the mitochondrial membrane permeability transition and mitochondrial ROS generation inhibited K1-CPS-mediated NLRP3 inflammasome activation. Furthermore, IL-1β secretion in macrophages infected with PLAK. pneumoniaewas shown to depend on NLRP3 but also on NLRC4 and TLR4. In macrophages infected with a K1-CPS deficiency mutant, an lipopolysaccharide (LPS) deficiency mutant, or K1-CPS and LPS double mutants, IL-1β secretion levels were lower than those in cells infected with wild-type PLAK. pneumoniae. Our findings indicate that K1-CPS is one of theKlebsiellafactors of PLAK. pneumoniaethat induce IL-1β secretion through the NLRP3 inflammasome.

scholarly journals NLRP3 Is a Critical Regulator of Inflammation and Innate Immune Cell Response during Mycoplasma pneumoniae Infection

2017 ◽  
Vol 86 (1) ◽  
Author(s):  
Jesus A. Segovia ◽  
Te-Hung Chang ◽  
Vicki T. Winter ◽  
Jacqueline J. Coalson ◽  
Marianna P. Cagle ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Mycoplasma Pneumoniae ◽  
Nlrp3 Inflammasome ◽  
Cell Activation ◽  
Immune Cell ◽  
Acute Infection ◽  
Respiratory Pathogen ◽  
Inflammasome Activation ◽  
Content Type

ABSTRACTMycoplasma pneumoniaeis an atypical bacterial respiratory pathogen known to cause a range of airway inflammation and lung and extrapulmonary pathologies. We recently reported that anM. pneumoniae-derived ADP-ribosylating and vacuolating toxin called community-acquired respiratory distress syndrome (CARDS) toxin is capable of triggering NLRP3 (NLR-family, leucine-rich repeat protein 3) inflammasome activation and interleukin-1β (IL-1β) secretion in macrophages. However, it is unclear whether the NLRP3 inflammasome is important for the immune response duringM. pneumoniaeacute infection. In the current study, we utilizedin vitroandin vivomodels ofM. pneumoniaeinfection to characterize the role of the NLRP3 inflammasome during acute infection.M. pneumoniae-infected macrophages deficient for inflammasome components NLRP3, ASC (apoptosis speck-like protein containing a caspase activation and recruitment domain), or caspase-1 failed to process and secrete IL-1β. The MyD88/NF-κB signaling pathway was found to be critical for proinflammatory gene expression in macrophages infected withM. pneumoniae. C57BL/6 mice deficient for NLRP3 expression were unable to produce IL-1β in the airways during acute infection, and lack of this inflammatory response led to deficient immune cell activation and delayed bacterial clearance. These findings are the first to report the importance of the NLRP3 inflammasome in regulating the inflammatory response and influencing the progression ofM. pneumoniaeduring acute infection.

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