scholarly journals Structural mechanism of CARD8 regulation by DPP9

2021 ◽  
Author(s):  
Humayun Sharif ◽  
L. Robert Hollingsworth ◽  
Andrew R. Griswold ◽  
Jeffrey C. Hsiao ◽  
Qinghui Wang ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Ternary Complex ◽  
Proteasomal Degradation ◽  
Full Length ◽  
Inflammasome Activation ◽  
Structural Mechanism ◽  
Danger Signals ◽  
Caspase 1 ◽  
Recognition Receptor

SUMMARYCARD8 is a germline-encoded pattern recognition receptor that detects intracellular danger signals. Like the related inflammasome sensor NLRP1, CARD8 undergoes constitutive autoprocessing within its function-to-find domain (FIIND), generating two polypeptides that stay associated and autoinhibited. Certain pathogen- and danger-associated activities, including the inhibition of the serine dipeptidases DPP8 and DPP9 (DPP8/9), induce the proteasome-mediated degradation of the N-terminal (NT) fragment, releasing the C-terminal (CT) fragment to form a caspase-1 activating inflammasome. DPP8/9 also bind directly to the CARD8 FIIND, but the role that this interaction plays in CARD8 inflammasome regulation is not yet understood. Here, we solved several cryo-EM structures of CARD8 bound to DPP9, with or without the DPP inhibitor Val-boroPro (VbP), which revealed a ternary complex composed of one DPP9, the full-length CARD8, and one CARD8-CT. Through structure-guided biochemical and cellular experiments, we demonstrated that DPP9’s structure restrains CARD8-CT after proteasomal degradation. Moreover, although DPP inhibitors do not directly displace CARD8 from DPP9 in vitro, we show that they can nevertheless destabilize this complex in cells. Overall, these results demonstrate that DPP8/9 inhibitors cause CARD8 inflammasome activation via at least two distinct mechanisms, one upstream and one downstream of the proteasome.

scholarly journals NLRP3 inflammasome assembly is regulated by phosphorylation of the pyrin domain

2017 ◽  
Vol 214 (6) ◽  
pp. 1725-1736 ◽  
Author(s):  
Andrea Stutz ◽  
Carl-Christian Kolbe ◽  
Rainer Stahl ◽  
Gabor L. Horvath ◽  
Bernardo S. Franklin ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Cell Death ◽  
Proinflammatory Cytokines ◽  
Inflammasome Activation ◽  
Phosphorylation Sites ◽  
Danger Signals ◽  
Pyrin Domain ◽  
Charge Interaction ◽  
Phosphatase 2A ◽  
Recognition Receptor

NLRP3 is a cytosolic pattern recognition receptor that senses microbes and endogenous danger signals. Upon activation, NLRP3 forms an inflammasome with the adapter ASC, resulting in caspase-1 activation, release of proinflammatory cytokines and cell death. How NLRP3 activation is regulated by transcriptional and posttranslational mechanisms to prevent aberrant activation remains incompletely understood. Here, we identify three conserved phosphorylation sites in NLRP3 and demonstrate that NLRP3 activation is controlled by phosphorylation of its pyrin domain (PYD). Phosphomimetic residues in NLRP3 PYD abrogate inflammasome activation and structural modeling indicates that phosphorylation of the PYD regulates charge–charge interaction between two PYDs that are essential for NLRP3 activation. Phosphatase 2A (PP2A) inhibition or knock-down drastically reduces NLRP3 activation, showing that PP2A can license inflammasome assembly via dephosphorylating NLRP3 PYD. These results propose that the balance between kinases and phosphatases acting on the NLRP3 PYD is critical for NLRP3 activation.

scholarly journals Rabeprazole inhibits inflammatory reaction by inhibition of cell pyroptosis in gastric epithelial cells

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Jing Xie ◽  
Long Fan ◽  
Liya Xiong ◽  
Peiyu Chen ◽  
Hongli Wang ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Clinical Sample ◽  
Critical Role ◽  
Enzyme Linked Immunosorbent Assay ◽  
Inflammasome Activation ◽  
Peptic Ulcers ◽  
Gastric Epithelial Cells ◽  
Caspase 1 ◽  
H Pylori

Abstract Background Helicobacter pylori (H. pylori) is a common pathogen in development of peptic ulcers with pyroptosis. Rabeprazole, a critical component of standard triple therapy, has been widely used as the first-line regimen for H. pylori infectious treatment. The aim of this study to explore the function of Rabeprazole on cell pyroptosis in vitro. Methods The clinical sample from patients diagnosed with or without H. pylori-infection were collected to analyze by Immunohistochemistry (IHC). Real-time quantitative PCR (qPCR), western blot (WB) and enzyme linked immunosorbent assay (Elisa) were performed to analyze the effect of Rabeprazole on cell pyroptosis, including LDH, IL-1β and IL-18. Results In this study, we showed that Rabeprazole regulated a phenomenon of cell pyroptosis as confirmed by lactate dehydrogenase (LDH) assay. Further results showed that Rabeprazole inhibited cell pyroptosis in gastric epithelial cells by alleviating GSDMD-executed pyroptosis, leading to decrease IL-1β and IL-18 mature and secretion, which is attributed to NLRP3 inflammasome activation inhibition. Further analysis showed that ASC, NLRP3 and Caspase-1, was significantly repressed in response to Rabeprazole stimulation, resulting in decreasing cleaved-caspase-1 expression. Most important, NLRP3 and GSDMD is significantly increased in gastric tissue of patients with H. pylori infection. Conclusion These findings revealed a critical role of Rabeprazole in cell pyroptosis in patients with H. pylori infection, suggesting that targeting cell pyroptosis is an alternative strategy in improving H. pylori treatment.

scholarly journals The Essential Oil of Artemisia argyi H.Lév. and Vaniot Attenuates NLRP3 Inflammasome Activation in THP-1 Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Pengxiao Chen ◽  
Qi Bai ◽  
Yanting Wu ◽  
Qiongzhen Zeng ◽  
Xiaowei Song ◽  
...  
Keyword(s):  
Essential Oil ◽  
Nlrp3 Inflammasome ◽  
Therapeutic Potential ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
Artemisia Argyi ◽  
Nlrp3 Inflammasome Activation ◽  
Long Time

Artemisia argyi H. Lév. and Vaniot is a traditional medical herb that has been used for a long time in China and other Asian counties. Essential oil is the main active fraction of Artemisia argyi H. Lév. and Vaniot, and its anti-inflammatory potential has been observed in vitro and in vivo. Here, we found that the essential oil of Artemisia argyi H. Lév. and Vaniot (EOAA) inhibited monosodium urate (MSU)- and nigericin-induced NLRP3 inflammasome activation. EOAA suppressed caspase-1 and IL-1β processing and pyroptosis. NF-κB p65 phosphorylation and translocation were also inhibited. In addition, EOAA suppressed nigericin-induced NLRP3 inflammasome activation without blocking ASC oligomerization, suggesting that it may inhibit NLRP3 inflammasome activation by preventing caspase-1 processing. Our study thus indicates that EOAA inhibits NLRP3 inflammasome activation and has therapeutic potential against NLRP3-driven diseases.

scholarly journals Activation of GSDME compensates for GSDMD deficiency in a mouse model of NLRP3 inflammasomopathy

2021 ◽  
Author(s):  
Chun Wang ◽  
Tong Yang ◽  
Jianqiu Xiao ◽  
Canxin Xu ◽  
Yael Alippe ◽  
...  
Keyword(s):  
Inflammatory Disease ◽  
Early Death ◽  
Organ Damage ◽  
Caspase 8 ◽  
Inflammasome Activation ◽  
Inflammatory Pathway ◽  
Disease Symptoms ◽  
Caspase 1 ◽  
Inflammatory Stimuli

AbstractThe D301N NLRP3 mutation in mice (D303N in humans) causes severe multi-organ damage and early death driven by the constitutively activated NLRP3 (NLRP3ca) inflammasome. Triggered inflammasomes activate caspase-1 to process IL-1 family cytokines and gasdermin D (GSDMD), generating N-terminal fragments, which oligomerize within the plasma membrane to form pores, which cause inflammatory cell death (pyroptosis) and through which IL-1β and IL-18 are secreted. GSDMD activation is central to disease symptoms since spontaneous inflammation in Nlrp3ca;Gsdmd-/- mice is negligible. Unexpectedly, when Nlrp3ca;Gsdmd-/- mice were challenged with LPS or TNF-α, they secreted high amounts of IL-1β and IL-18, suggesting an alternative GSDMD-independent inflammatory pathway. Here we show that GSDMD deficient macrophages subjected to inflammatory stimuli activate caspase-8, -3 and GSDME-dependent cytokine release and pyroptosis. Caspase-8, -3 and GSDME also activated pyroptosis when NLRP3 was stimulated in caspase-1 deficient macrophages. Thus, a salvage caspase-8, -3-GSDME inflammatory pathway is activated following NLRP3 activation when the canonical NLRP3-caspase-1-GSDMD is blocked. Surprisingly, the active metabolite of the GSDMD-inhibitor disulfiram, inhibited not only GSDMD but also GSDME-mediated inflammation in vitro and suppressed severe inflammatory disease symptoms in Nlrp3ca mice, a model for severe neonatal multisystem inflammatory disease. Although disulfiram did not directly inhibit GSDME, it suppressed inflammasome activation in GSDMD-deficient cells. Thus, the combination of inflammatory signals and NLRP3ca overwhelmed the protection provided by GSDMD deficiency, rewiring signaling cascades through caspase-8, -3 and GSDME to propagate inflammation. This functional redundancy suggests that concomitant inhibition of GSDMD and GSDME may be necessary to suppress disease in inflammasomopathy patients.

scholarly journals Callicarpa Nudiflora Extract Exerts Anti-Inflammatory Effect on H. Pylori-Associated Gastritis Through Repression of ROS/NLRP3/Caspase-1/IL-1β Signaling Axis

2021 ◽  
Author(s):  
Lili Li ◽  
Xiaohui Zhu ◽  
Xingxing Chai ◽  
Xiaoyu Chen ◽  
Xiaohua Su ◽  
...  
Keyword(s):  
Cell Damage ◽  
Underlying Mechanism ◽  
Inflammatory Factors ◽  
Inflammasome Activation ◽  
Ros Production ◽  
Gastric Diseases ◽  
Caspase 1 ◽  
Signaling Axis ◽  
H Pylori

Abstract Helicobacter pylori ( H. pylori ) is a major pathogenic factor for the development of gastric diseases including chronic gastritis and gastric cancer. Callicarpa nudiflora (CN), an air-dried leaves extract of Callicarpa nudiflora Hook. & Arn., has been found to exhibit a broad-spectrum antibacterial effect. In our study, we extracted the active ingredient from air-dried leaves of Callicarpa nudiflora, detected the effect of CN against H. pylori -infected GES-1 cells in vitro , and elucidated the underlying mechanism. GES-1 cells were cocultured with HPSS1 at MOI = 100:1 and treated with different concentrations of CN. Results indicated that CN not only significantly decreased cellular lactate dehydrogenase leakage, but also markedly attenuated H. pylori -induced cell apoptosis and ROS production in GSE-1 cells, therefore protecting gastric epithelial cells against injuries caused by H. pylori . CN also inhibited the secretions of inflammatory factors, such as tumor necrosis factor-α (TNF-α), IL-1β, IL-6 and IL-8. Furthermore, CN remarkably decreased the expression levels of NLRP3, PYCARD, active Caspase-1. In conclusion, CN exhibited highly efficient protective effect against H. pylori -induced gastritis and cell damage; Mechanismly, CN suppressed H. pylori -triggered inflammatory response and pyroptosis through depressing ROS production and NLRP3 inflammasome activation via ROS/NLRP3/IL-1β signaling axis.

scholarly journals Macrophage Uptake of Necrotic Cell DNA Activates the AIM2 Inflammasome to Regulate a Proinflammatory Phenotype in CKD

2018 ◽  
Vol 29 (4) ◽  
pp. 1165-1181 ◽  
Author(s):  
Takanori Komada ◽  
Hyunjae Chung ◽  
Arthur Lau ◽  
Jaye M. Platnich ◽  
Paul L. Beck ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Inflammasome Activation ◽  
Dna Uptake ◽  
Chronic Injury ◽  
Caspase 1 ◽  
Double Stranded Dna ◽  
Molecular Pattern ◽  
Macrophage Uptake

Nonmicrobial inflammation contributes to CKD progression and fibrosis. Absent in melanoma 2 (AIM2) is an inflammasome-forming receptor for double-stranded DNA. AIM2 is expressed in the kidney and activated mainly by macrophages. We investigated the potential pathogenic role of the AIM2 inflammasome in kidney disease. In kidneys from patients with diabetic or nondiabetic CKD, immunofluorescence showed AIM2 expression in glomeruli, tubules, and infiltrating leukocytes. In a mouse model of unilateral ureteral obstruction (UUO), Aim2 deficiency attenuated the renal injury, fibrosis, and inflammation observed in wild-type (WT) littermates. In bone marrow chimera studies, UUO induced substantially more tubular injury and IL-1β cleavage in Aim2−/− or WT mice that received WT bone marrow than in WT mice that received Aim2−/− bone marrow. Intravital microscopy of the kidney in LysM(gfp/gfp) mice 5–6 days after UUO demonstrated the significant recruitment of GFP+ proinflammatory macrophages that crawled along injured tubules, engulfed DNA from necrotic cells, and expressed active caspase-1. DNA uptake occurred in large vacuolar structures within recruited macrophages but not resident CX3CR1+ renal phagocytes. In vitro, macrophages that engulfed necrotic debris showed AIM2-dependent activation of caspase-1 and IL-1β, as well as the formation of AIM2+ ASC specks. ASC specks are a hallmark of inflammasome activation. Cotreatment with DNaseI attenuated the increase in IL-1β levels, confirming that DNA was the principal damage-associated molecular pattern in this process. Therefore, the activation of the AIM2 inflammasome by DNA from necrotic cells drives a proinflammatory phenotype that contributes to chronic injury in the kidney.

Over IFI16 expression increased inflammation in Hepatitis B Virus-Associated Glomerulonephritis by Regulating Caspase-1 and IL-1 ß

2020 ◽  
Author(s):  
zhaoqing zeng ◽  
yuyang li ◽  
jinhong yu ◽  
jing liu ◽  
shijun chen ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Cell Line ◽  
Renal Damage ◽  
Hbv Infection ◽  
Inflammatory Factors ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
B Virus

Abstract Aims & background: IFI16 plays an important role in innate immunity against invasive microbial infection by sensing double-stranded DNA viruses due to caspase-1-dependent inflammasome activation and subsequent maturation and secretion of IL-1β. However, the role of IFI16 in regulating the immune response to viruses in vivo and in vitro, especially in sensing hepatitis B virus (HBV), has not been examined. We hypothesized that the expression of IFI16 increases corresponding to HBV-mediated inflammation in patients with hepatitis B virus associated glomerulonephritis (HBV-GN), a condition which activates inflammatory mechanisms and causes renal damage. To test this hypothesis, we therefore analyzed the expression of IFI16 and inflammatory factors in HBV-GN tissues and cell lines relative to the inflammatory response to HBV infection. Methods: A total 75 patients with chronic nephritis(CN) including 50 with HBV-GN and 25 with chronic glomerulonephritis (CCN) involved in this study. Each CN patient received renal biopsy, and immunohistochemistry(IHC) was used to detect the expression of IFI16 and inflammatory factors Caspase-1 and IL-1β in the biopsy specimens. Following IFI16 was transfected in HBV-infected and HBV-uninfected human glomerular mesangial (HGM) cell line and HEK-293T cell line, expression of Caspase-1 and IL-1β were detected by Western blot and qRT- PCR. Results: IFI16 expression in HBV-GN biopsies (80.0%) was significantly higher than in CGN (24.0%) and positively correlated with caspase-1 and IL-1𝛽 expression in HBV-GN. In vitro, over expression IFI16 increased caspase-1 and IL-1𝛽 expression in HBV -infected HGM and HEK-293T. Conclusions: The elevation of IFI16 during HBV infection or replication may contribute to renal damage due to inflammation, thus providing a putative therapeutic target and a new avenue for researching the pathogenesis of HBV-GN.

scholarly journals Astragaloside IV Suppresses High Glucose-Induced NLRP3 Inflammasome Activation by Inhibiting TLR4/NF-κB and CaSR

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Bin Leng ◽  
Yingjie Zhang ◽  
Xinran Liu ◽  
Zhen Zhang ◽  
Yang Liu ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
High Glucose ◽  
Inflammasome Activation ◽  
Astragaloside Iv ◽  
Caspase 1 ◽  
Endothelial Inflammation ◽  
Nlrp3 Inflammasome Activation ◽  
Anti Inflammatory

Long-term exposure to high glucose induces vascular endothelial inflammation that can result in cardiovascular disease. Astragaloside IV (As-IV) is widely used for anti-inflammatory treatment of cardiovascular diseases. However, its mechanism of action is still not fully understood. In this study, we investigated the effect of As-IV on high glucose-induced endothelial inflammation and explored its possible mechanisms. In vivo, As-IV (40 and 80 mg/kg/d) was orally administered to rats for 8 weeks after a single intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). In vitro, human umbilical vein endothelial cells (HUVECs) were treated with high glucose (33 mM glucose) in the presence or absence of As-IV, NPS2143 (CaSR inhibitor), BAY 11-7082 (NF-κB p65 inhibitor), and INF39 (NLRP3 inhibitor), and overexpression of CaSR was induced by infection of CaSR-overexpressing lentiviral vectors to further discuss the anti-inflammatory property of As-IV. The results showed that high glucose increased the expression of interleukin-18 (IL-18), interleukin-1β (IL-1β), NLRP3, caspase-1, and ASC, as well as the protein level of TLR4, nucleus p65, and CaSR. As-IV can reverse these changes in vivo and in vitro. Meanwhile, NPS2143, BAY 11-7082, and INF39 could significantly abolish the high glucose-enhanced NLRP3, ASC, caspase-1, IL-18, and IL-1β expression in vitro. In addition, both NPS2143 and BAY 11-7082 attenuated high glucose-induced upregulation of NLRP3, ASC, caspase-1, IL-18, and IL-1β expression. In conclusion, this study suggested that As-IV could inhibit high glucose-induced NLRP3 inflammasome activation and subsequent secretion of proinflammatory cytokines via inhibiting TLR4/NF-κB signaling pathway and CaSR, which provides new insights into the anti-inflammatory activity of As-IV.

scholarly journals OLT1177, a β-sulfonyl nitrile compound, safe in humans, inhibits the NLRP3 inflammasome and reverses the metabolic cost of inflammation

2018 ◽  
Vol 115 (7) ◽  
pp. E1530-E1539 ◽  
Author(s):  
Carlo Marchetti ◽  
Benjamin Swartzwelter ◽  
Fabia Gamboni ◽  
Charles P. Neff ◽  
Katrin Richter ◽  
...  
Keyword(s):  
Human Blood ◽  
Nlrp3 Inflammasome ◽  
Inflammatory Diseases ◽  
Plasma Concentrations ◽  
Metabolic Cost ◽  
Inflammasome Activation ◽  
Potassium Efflux ◽  
Caspase 1 ◽  
Healthy Humans

Activation of the NLRP3 inflammasome induces maturation of IL-1β and IL-18, both validated targets for treating acute and chronic inflammatory diseases. Here, we demonstrate that OLT1177, an orally active β-sulfonyl nitrile molecule, inhibits activation of the NLRP3 inflammasome. In vitro, nanomolar concentrations of OLT1177 reduced IL-1β and IL-18 release following canonical and noncanonical NLRP3 inflammasome activation. The molecule showed no effect on the NLRC4 and AIM2 inflammasomes, suggesting specificity for NLRP3. In LPS-stimulated human blood-derived macrophages, OLT1177 decreased IL-1β levels by 60% and IL-18 by 70% at concentrations 100-fold lower in vitro than plasma concentrations safely reached in humans. OLT1177 also reduced IL-1β release and caspase-1 activity in freshly obtained human blood neutrophils. In monocytes isolated from patients with cryopyrin-associated periodic syndrome (CAPS), OLT1177 inhibited LPS-induced IL-1β release by 84% and 36%. Immunoprecipitation and FRET analysis demonstrated that OLT1177 prevented NLRP3-ASC, as well as NLRP3-caspase-1 interaction, thus inhibiting NLRP3 inflammasome oligomerization. In a cell-free assay, OLT1177 reduced ATPase activity of recombinant NLRP3, suggesting direct targeting of NLRP3. Mechanistically, OLT1177 did not affect potassium efflux, gene expression, or synthesis of the IL-1β precursor. Steady-state levels of phosphorylated NF-κB and IkB kinase were significantly lowered in spleen cells from OLT1177-treated mice. We observed reduced IL-1β content in tissue homogenates, limited oxidative stress, and increased muscle oxidative metabolism in OLT1177-treated mice challenged with LPS. Healthy humans receiving 1,000 mg of OLT1177 daily for 8 d exhibited neither adverse effects nor biochemical or hematological changes.

scholarly journals Stavudine Reduces NLRP3 Inflammasome Activation and Upregulates Aβ-Autophagy

2018 ◽  
Author(s):  
Francesca La Rosa ◽  
Marina Saresella ◽  
Ivana Marventano ◽  
Federica Piancone ◽  
Enrico Ripamonti ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Inflammasome Activation ◽  
Clinical Scenario ◽  
Rt Pcr ◽  
Reverse Transcriptase Inhibitors ◽  
Beneficial Effects ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation ◽  
Aβ Clearance

AbstractAlzheimer’s disease (AD) is associated with amyloid-beta (Aβ) deposition and neuroinflammation, possibly driven by activation of the NLRP3 inflammasome. Nucleoside reverse transcriptase inhibitors (NRTI) hamper the assembly of the NLRP3 inflammasome; we analyzed whether stavudine (D4T), a prototypical NRTI, modulates Aβ-mediated inflammasome activation; because neuroinflammation impairs Aβ clearance by phagocytes, phagocytosis and autophagy were examined as well. THP-1-derived macrophages were stimulated in vitro with Aβ42 alone or after LPS priming with/without D4T. NLRP3 and TREM2 expression was analyzed by RT-PCR, phagocytosis and ASC-Speck by AmnisFlowSight, NLRP3-produced cytokines by ELISA, authophagy by P-ELISA evaluation of P-ERK and P-AKT. Results showed that IL1β, IL18 and caspase-1 were increased whereas Aβ-phagocytosis and TREM2 were reduced in LPS+Aβ42-stimulated cells. D4T reduced NLRP3 assembly as well as IL18 and caspase-1 production, but not IL1β, phagocytosis, and TREM2. P-AKT expression was augmented and P-ERK was reduced by D4T, suggesting a stimulatory effect on autophagy. D4T reduces NLRP3 inflammasome-associated inflammation, possibly restoring autophagy, in an in vitro model of AD; it will be interesting to verify its possibly beneficial effects in the clinical scenario.

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