NLRP3 Inflammasome Research Articles

ABHD8 antagonizes inflammation by facilitating chaperone-mediated autophagy-mediated degradation of NLRP3

ABSTRACT The NLRP3 inflammasome is a multiprotein complex that plays a vital role in the innate immune system in response to microbial infections and endogenous danger signals. Aberrant activation of the NLRP3 inflammasome is implicated in a spectrum of inflammatory and autoimmune diseases, emphasizing the necessity for precise regulation of the NLRP3 inflammasome to maintain immune homeostasis. The protein level of NLRP3 is a limiting step for inflammasome activation, which must be tightly controlled to avoid detrimental consequences. Here, we demonstrate that ABHD8, a member of the α/β-hydrolase domain-containing (ABHD) family, interacts with NLRP3 and promotes its degradation through the chaperone-mediated autophagy (CMA) pathway. ABHD8 acts as a scaffold to recruit palmitoyltransferase ZDHHC12 to NLRP3 for its palmitoylation as well as subsequent CMA-mediated degradation. Notably, ABHD8 deficiency results in the stabilization of NLRP3 protein and promotes NLRP3 inflammasome activation. We further confirm that ABHD8 overexpression ameliorates LPS- or alum-triggered NLRP3 inflammasome activation in vivo. Interestingly, the nucleocapsid (N) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impairs the ABHD8-NLRP3 association, resulting in an elevation in NLRP3 protein level and excessive inflammasome activation. These findings demonstrate that ABHD8 May represent a potential therapeutic target in conditions associated with NLRP3 inflammasome dysregulation. Abbreviations: 3-MA: 3-methyladenine; ABHD: α/β-hydrolase domain-containing; BMDMs: Bone marrow-derived macrophages; CFZ: carfilzomib; CHX: cycloheximide; CMA: chaperone-mediated autophagy; CQ: chloroquine; DAMPs: danger/damage-associated molecular patterns; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; LAMP2A: lysosomal associated membrane protein 2A; NH4Cl: ammonium chloride; NLRP3: NLR family pyrin domain containing 3; PAMPs: pathogen-associated molecular patterns; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.

Targeting NLRP3 inhibits AML progression by inducing PERK/eIF2-mediated apoptosis

BackgroundAcute myeloid leukemia (AML) is characterized by the abnormal proliferation of myeloid precursor cells and presents significant challenges in treatment due to its heterogeneity. Recently, the NLRP3 inflammasome has emerged as a potential contributor to AML pathogenesis, although its precise mechanisms remain poorly understood.MethodsPublic genome datasets were utilized to evaluate the expression of NLRP3 inflammasome-related genes (IL-1β, IL-18, ASC, and NLRP3) in AML patients compared to healthy individuals. CRISPR/Cas9 technology was employed to generate NLRP3-deficient MOLM-13 AML cells, followed by comprehensive characterization using real-time PCR, western blotting, FACS analysis, and transmission electron and immunofluorescence microscopy. Proteomic analyses were conducted to identify NLRP3-dependent alterations in protein levels, with a focus on the eIF2 kinase PERK-mediated signaling pathways. Additionally, in vivo studies were performed using a leukemic mouse model to elucidate the pathogenic role of NLRP3 in AML.ResultsElevated expression of NLRP3 was significantly associated with diminished overall survival in AML patients. Genetic deletion, pharmacological inhibition and silencing by RNA interference of NLRP3 led to decreased AML cell survival through the induction of apoptosis. Proteomic analyses uncovered NLRP3-dependent alterations in protein translation, characterized by enhanced eIF2α phosphorylation in NLRP3-deficient AML cells. Moreover, inhibition of PERK-mediated eIF2α phosphorylation reduced apoptosis by downregulating pro-apoptotic Bcl-2 family members. In vivo studies demonstrated reduced leukemic burden in mice engrafted with NLRP3 knockout AML cells, as evidenced by alleviated leukemic symptoms.ConclusionOur findings elucidate the involvement of the NLRP3/PERK/eIF2 axis as a novel driver of AML cell survival. Targeting NLRP3-induced signaling pathways, particularly through the PERK/eIF2 axis, presents a promising therapeutic strategy for AML intervention. These insights into the role of the NLRP3 inflammasome offer potential avenues for improving the prognosis and treatment outcomes of AML patients.

A composite patch loaded with 2-Deoxy Glucose facilitates cardiac recovery after myocardial infarction via attenuating local inflammatory response

Local inflammatory microenvironment in the early stage of myocardial infarction (MI) severely impaired cardiac recovery post-MI. Macrophages play a pivotal role in this process. A classical glycolytic inhibitor, 2-Deoxy-Glucose (2-DG), has been found to regulate the excessive pro-inflammatory macrophage polarization in the infarcted myocardium. This study investigated the effect of 2-DG-loaded chitosan/gelatin composite patch on the infarct microenvironment post-MI and its impact on cardiac repair. The results showed that the 2-DG patch significantly inhibited the expression of inflammatory cytokines, alleviated reactive oxygen species (ROS) accumulation, repressed the proinflammatory polarization of macrophages, attenuated local inflammatory microenvironment in the ischemic hearts, as well as improved cardiac function, reduced scar size, and promoted angiogenesis post-MI. In terms of mechanism, 2-DG exerts anti-inflammatory effects through inhibiting the NF-κB signaling pathway and reducing the assembly and activation of the NLRP3 inflammasome. These findings suggest that 2-DG composite patch may represent a promising therapeutic strategy for cardiac repair after MI.

PM2.5 Induces Pyroptosis via Activation of the ROS/NF-κB Signaling Pathway in Bronchial Epithelial Cells.

Background and Objectives: Fine particulate matter, PM2.5, is becoming a major threat to human health, particularly in terms of respiratory diseases. Pyroptosis is a recently discovered and distinct form of cell death, characterized by pore formation in the cell membrane and secretions of proinflammatory cytokines. There has been little research on the effect of PM2.5 on pyroptosis, especially in airway epithelium. We investigated whether PM2.5-related oxidative stress induces pyroptosis in bronchial epithelial cells and defined the underlying mechanisms. Materials and Methods: After exposure of a BEAS-2B cell line to PM2.5 concentration of 20 µg/mL, reactive oxygen species (ROS) levels, parameters related to pyroptosis, and NF-κB signaling were measured by Western blotting, immunofluorescence, and ELISA (Enzyme-linked immunosorbent assay). Results: PM2.5 induced pyroptotic cell death, accompanied by LDH (Lactate dehydrogenase) release and increased uptake of propidium iodide in a dose-dependent manner. PM2.5 activated the NLRP3-casp1-gasdermin D pathway, with resulting secretions of the proinflammatory cytokines IL-1β and IL-18. The pyroptosis activated by PM2.5 was alleviated significantly by NLRP3 inhibitor. In PM2.5-exposed BEAS-2B cells, levels of intracellular ROS and NF-κB p65 increased. ROS scavenger inhibited the expression of the NLRP3 inflammasome, and the NF-κB inhibitor attenuated pyroptotic cell death triggered by PM2.5 exposure, indicating that the ROS/NF-κB pathway is involved in PM2.5-induced pyroptosis. Conclusions: These findings show that PM2.5 exposure can cause cell injury by NLRP3-inflammasome-mediated pyroptosis by upregulating the ROS/NF-κB pathway in airway epithelium.

RSPO3 regulates the radioresistance of Non-Small cell lung cancer cells via NLRP3 Inflammasome-Mediated pyroptosis

PurposeRadioresistance is a significant challenge in the radiotherapy of non-small cell lung cancer (NSCLC). This study aimed to investigate the role of R-spondin 3 (RSPO3) in regulating NSCLC radioresistance. Methods and MaterialsRNA sequencing was performed to analyze genes that are differentially expressed in radioresistant NSCLC cell lines. RSPO3 overexpression and knockdown experiments were conducted to assess its impact on radiosensitivity. The involvement of the β-catenin-NF-κB signaling pathway and the NLRP3 inflammasome in RSPO3-mediated radiosensitivity was also evaluated. In vivo experiments were conducted using a clinical-grade anti-RSPO3 antibody (OMP-131R10/rosmantuzumab) to assess its impact on radiation-induced pyroptosis and subsequent anti-tumor immunity. ResultsRSPO3 expression was downregulated in radioresistant NSCLC cells. Overexpression of RSPO3 increased NSCLC radiosensitivity through the induction of pyroptosis, which was mediated by the β-catenin-NF-κB signaling pathway and the NLRP3 inflammasome. The anti-RSPO3 antibody effectively blocked radiation-induced pyroptosis and anti-tumor immunity in vivo. Conversely, upregulation of RSPO3 enhanced NSCLC tumor radiosensitivity. ConclusionsThe findings demonstrated that RSPO3 plays a crucial role in regulating NSCLC radioresistance via NLRP3 mediated pyroptosis. Targeting the RSPO3-NLRP3 inflammasome axis may offer a potential therapeutic strategy to enhance the efficacy of radiotherapy for NSCLC patients.

Rapamycin mitigates organ damage by autophagy-mediated NLRP3 inflammasome inactivation in sepsis.

Autophagy activation can alleviate sepsis-induced organ injuries. Rapamycin (Rap) has emerged as an autophagy regulator in multiple forms of organ injuries. This study aimed to assess whether Rap protects rats from cecal ligation and puncture (CLP)-induced sepsis through autophagy-mediated inactivation of the NLRP3 inflammasome. Rats were allocated to the sham, CLP, Rap (10 mg/kg), or 3-Methyladenine (3-MA) (15 mg/kg) groups. A rat CLP model was established. The survival of rats and lung wet-to-dry weight ratio in each group was assessed. Blood biochemical indexes and oxidative stress-related factors were analyzed with an automatic biochemical analyzer. The bacterial counts of blood and organs were monitored. The degrees of myeloperoxidase of the ileum, inflammation-related indexes, and pathological changes in the tissues were detected by ELISA and hematoxylin-eosin staining. The levels of NLRP3 inflammasome and autophagy-related factors were analyzed by Western blot. Rap increased the survival and SOD activity, and repressed ALT, AST, BUN, SCr, MDA, and inflammation-related marker levels in CLP rats, it also restrained the bacterial counts of blood, lung, liver, and kidney in CLP rats; the effects of 3-MA on CLP rats on the above-mentioned indicators were opposite to those of Rap. Additionally, Rap alleviated the pathological injury of the lung, liver, and kidney, which was the opposite to the effect of 3-MA on CLP rats. Furthermore, Rap mitigated the ASC, Pro-caspase 1, and NLRP3 levels and increased the Beclin-1 levels and the LC3II/LC3I ratio in the organ tissues. Collectively, autophagy activation can mitigate organ damage by suppressing the NLRP3 inflammasome in sepsis rats.

Abstract P359: Greater NLRP3 in Males Results in a More Pro-Inflammatory T cell Profile, but Comparable Increases in Blood Pressure to Females with DOCA-Salt

T cells contribute to the development of hypertension, but what mediates T cell activation in hypertension is still being investigated. The NLRP3 inflammasome is a key mediator of the inflammatory response, and NLRP3 contributes to deoxycorticosterone acetate (DOCA)-salt hypertension in male mice. Little is known regarding the role of NLRP3 in hypertensive females, but we previously published that greater increases in blood pressure (BP) in male DOCA-salt rats vs females is associated with a more pro-inflammatory T cell profile. The goal of the current study was to test the hypothesis that greater NLRP3 activation in males contributes to greater increases in BP and a more pro-inflammatory T cell profile than in females. Methods: Initial studies measured NLRP3 and IL1-β mRNA expression in kidneys of uninephrectomized (UNX) male and female Sprague Dawley rats randomized to vehicle or DOCA treatment (n=5/group). Additional UNX male and female rats were randomized to DOCA plus vehicle or an NLRP3 inhibitor, MCC950 (10 mg/kg), for 3 weeks. BP was measured via telemetry (n=5/group). Kidneys were harvested for flow cytometric analysis of T cells. Data were compared via 2-way ANOVA. Results: DOCA increased renal NLRP3 and IL1-β mRNA in males and females (NLRP3: P treatment <0.0001, P sex =0.0014; IL1-β: P treatment <0.0001, P sex =0.05), and increases were greater in males (P interaction =0.04, P interaction =0.02, respectively). DOCA treatment increased BP in males (105±4 to 190±1 mmHg) and females (97±3 to 167±5 mmHg), and treatment with MCC950 attenuated DOCA-induced increases in BP in both sexes (males: 107±3 to 174±2 mmHg; females: 98±3 to 159±7 mmHg; P treatment =0.004). Terminal BP values were compared and while BP was higher in males, the impact of MCC950 was comparable between the sexes (P sex =0.0001; P interaction =0.4). However, MCC950 attenuated DOCA-induced increases in renal CD4 + T cells and Th17 cells to a greater degree in males than in females (CD4+: P treatment <0.001, P sex =0.03, P interaction =0.04; Th17 cells: P treatment <0.001, P sex =0.001, P interaction =0.04). Conclusions: NLRP3 contributes to the development of DOCA-salt induced increases in BP and inflammation in both males and females. However, males have greater NLRP3-mediated increases in renal T cells than females. The impact of this mechanism on renal function and the potential for targeted hypertensive therapies needs to be further examined.

Nrf2 Deficiency Exacerbates Parkinson's Disease by Aggravating NLRP3 Inflammasome Activation in MPTP-Induced Mouse Models and LPS-Induced BV2 Cells.

Parkinson's disease (PD) is a movement disorder characterized by the progressive loss of dopamine neurons. Microglia-mediated neuroinflammation drives disease progression and becomes a critical factor in neuronal degeneration. Recent studies have found that nuclear factor-erythroid 2-related-2 (Nrf2) expression levels are reduced during aging and neurodegenerative diseases, but its regulatory mechanism on microglia-induced neuroinflammation has not been fully elucidated. In vivo, we used the intraperitoneal injection of the neurotoxic drug neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to establish an animal model of PD and, at the same time, administered Nrf2 inhibitors ML385 and dimethyl fumarate to regulate Nrf2 protein levels. In vitro, we used si-RNA to knock out the Nrf2 gene to intervene in BV2 cells and used lipopolysaccharide (LPS) to stimulate and induce the cell model. The study found that inhibition of Nrf2 expression aggravated the motor defects of PD mice, accompanied by a significant loss of dopaminergic neurons in the substantia nigra and striatum of the brain. In addition, after inhibition of Nrf2, the malondialdehyde (MDA) level in the substantia nigra of the midbrain of mice increased, and the levels of superoxide dismutase (SOD) and heme oxygenase-1 (HO-1) decreased, accompanied by the proliferation of microglia and astrocytes. In addition, the activation of the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome, the assembly of apoptosis-associated speck-like protein containing a CARD (ASC) protein in microglia, and the release of downstream inflammatory factors caspase-1 and interleukin (IL)-1β, were aggravated. At the cellular level, it was found that knocking out the expression of Nrf2 would aggravate the activation of NLRP3 inflammasomes and the assembly of ASC in LPS-induced BV2 cells. Inhibited Nrf2 activity can reduce the downstream antioxidant enzyme HO-1 and antioxidant levels, induce NLRP3 inflammasome activation and ASC protein assembly in microglia, and ultimately aggravate PD inflammatory response and dopamine neuron degeneration.

Linoleyl acetate and mandenol alleviate HUA-induced ED via NLRP3 inflammasome and JAK2/STAT3 signalling conduction in rats.

Hyperuricemia (HUA) is characterized by elevated blood uric acid levels, which can increase the risk of erectile dysfunction (ED). Clinical studies have demonstrated satisfactory efficacy of a traditional Chinese medicine formula QYHT decoction in improving ED. Furthermore, the main monomeric components of this formula, linoleyl acetate and mandenol, demonstrate promise in the treatment of ED. This study established an ED rat model induced by HUA and the animals were administered with linoleyl acetate and mandenol. HE and TUNEL were performed to detect tissue changes, ELISA to measure the levels of serum testosterone (T), MDA, NO, CRP, and TNF-α and qPCR and WB to assess the expression levels of NLRP3, ASC, Caspase-1, JAK2, and STAT3 in whole blood. The findings showed that linoleyl acetate and mandenol improved kidney tissue morphology, reduced cell apoptosis in penile tissue, significantly increased T and NO levels, while substantially decreasing levels of MDA, CRP, and TNF-α. Meanwhile, the expression of NLRP3, ASC, and Caspase-1 mRNAs and proteins was markedly reduced, and the phosphorylation of JAK2 and STAT3 was inhibited. These findings were further validated through faecal microbiota transplantation results. Taken together, linoleyl acetate and mandenol could inhibit NLRP3 inflammasome activation, reduce inflammatory and oxidative stress responses, suppress the activity of JAK-STAT signalling pathway, ultimately providing a potential treatment for HUA-induced ED.

STAT3 promotes NLRP3 inflammasome activation by mediating NLRP3 mitochondrial translocation

Recognition of the translocation of NLRP3 to various organelles has provided new insights for understanding how the NLRP3 inflammasome is activated by different stimuli. Mitochondria have already been demonstrated to be the site of NLRP3 inflammasome activation, and the latest research suggests that NLRP3 is first recruited to mitochondria, then disassociated, and subsequently recruited to the Golgi network. Although some mitochondrial factors have been found to contribute to the recruitment of NLRP3 to mitochondria, the detailed process of NLRP3 mitochondrial translocation remains unclear. Here, we identify a previously unknown role for Signal transducer and activator of transcription-3 (STAT3) in facilitating the translocation of NLRP3 to mitochondria. STAT3 interacts with NLRP3 and undergoes phosphorylation at Ser727 in response to several NLRP3 agonists, enabling the translocation of STAT3 and thus the bound NLRP3 to mitochondria. Disruption of the interaction between STAT3 and NLRP3 impairs the mitochondrial localization of NLRP3, specifically suppressing NLRP3 inflammasome activation both in vitro and in vivo. In summary, we demonstrate that STAT3 acts as a transporter for mitochondrial translocation of NLRP3 and provide new insight into the spatial regulation of NLRP3.

Diacetoxy-6-gingerdiol protects the extracellular matrix of nucleus pulposus cells and ameliorates intervertebral disc degeneration by inhibiting the IL-1β-mediated NLRP3 pathway.

Intervertebral disc degeneration (IDD) is a common cause of low back pain, causing a huge emotional and economic burden on patients and society. Reduction of nucleus pulposus cells (NPC) and extracellular matrix (ECM) is the main feature of IDD, and NPC is the main source of ECM. Thermal apoptosis is a newly discovered form of cell death in recent years that differs significantly from apoptosis in terms of molecular mechanisms and cellular morphological changes. Diacetoxy-6-gingerdiol(D-6-G), a type of gingerol, has anti-inflammatory and antioxidant effects, but whether it has an inhibitory effect on cellular pyroptosis is not clear. Therefore, in the present study, we investigated the effect of D-6-G on the ECM of the nucleus pulposus oblongata under IL-1β treatment, as well as the mechanism of its effect on NLRP3 inflammasome and cellular focal death. In vitro cellular experiments demonstrated that D-6-G could bind to and inhibit the activity of NLRP3 inflammasome, and interestingly, D-6-G could also inhibit cellular pyroptosis and protect the nucleus pulposusry cellular microenvironment by activating the Nrf2/HO-1 axis. In conclusion, we found that D-6-G could inhibit NLRP3 inflammatory vesicle activity as well as cellular pyroptosis in NPCs and protect the ECM, suggesting the potential of D-6-G to delay IDD.

NOX2 mediates NLRP3/ROS facilitating nasal mucosal epithelial inflammation in chronic rhinosinusitis with nasal polyps

BackgroundPrevious investigations have provided limited insight into the role of oxidative stress in nasal mucosa inflammation. The aim of this study was to investigate the mechanism of oxidative stress in the epithelial cells of chronic rhinosinusitis with nasal polyps CRSwNP utilizing single-cell RNA sequencing data. MethodsSingle-cell RNA sequencing data from HRA000772 were used to assess oxidative stress, inflammasome activation, and nicotinamide adenine dinucleotide phosphate oxidases (NOXs) expression in epithelial cells via integrative rank-based gene set enrichment analysis. The localization of reactive oxygen species (ROS) and NOX2 in nasal mucosa and cell models was visualized using fluorescent probes and immunohistochemistry, respectively. Functional studies on NOX2 involved siRNA and plasmid transfections in vitro, while Nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activity was examined using the inducer TMAO and the inhibitor MCC950. ResultsSingle-cell RNA sequencing data suggested an increase of oxidative stress score and NLRP3 inflammasome score in CRSwNP epithelial cells. Vitro experiments demonstrated that lipopolysaccharide could induce ROS accumulation, NLRP3 inflammasome activation and epithelial alarmin expression. MCC950 inhibited the expression of epithelia alarmin in vitro. Elevated NOX2 in CRSwNP epithelial cells was associated with increased ROS, NLRP3 inflammasome activation, and epithelial alarmin expression. NOX2-targeted siRNA inhibited these effects in vitro. Moreover, TMAO reversed the downregulation of epithelial alarmins without impacting ROS levels. ConclusionThis study highlights the crucial role of NOX2 as a key regulator of ROS accumulation and NLRP3 inflammasome activation in CRSwNP, underscoring its potential as a valuable therapeutic target for CRSwNP.

Discovery of natural product derivative triptolidiol as a direct NLRP3 inhibitor by reducing K63-specific ubiquitination.

NLRP3 is up-regulated in inflammatory and autoimmune diseases. The development of NLRP3 inhibitors is challenged by the identification of compounds with distinct mechanisms of action avoiding side effects and toxicity. Triptolide is a natural product with multiple anti-inflammatory activities, but a narrow therapeutic window. Natural product triptolide derivatives were screened for NLRP3 inhibitors in human THP-1 and mouse bone marrow-derived macrophages. The efficacy of potent NLRP3 inhibitors was evaluated in LPS-induced acute lung injury and septic shock models. Triptolidiol was identified as a selective inhibitor of NLRP3 with high potency. Triptolidiol inactivated the NLRP3 inflammasome in human THP-1 and mouse primary macrophages primed with LPS. Triptolidiol specifically inhibited pro-caspase 1 cleavage downstream of NLRP3, but not AIM2 or NLRC4 inflammasomes. Based on the structure-activity relationship study, the C8-β-OH group was critical for its binding to NLRP3. Triptolidiol exhibited a submicromolar KD for NLRP3, binding to residue C280. This binding prevented the interaction of NLRP3 with NEK7, the key regulator of NLRP3 inflammasome oligomerization and assembly, but not with the inflammasome adaptor protein ASC. Triptolidiol decreased the K63-specific ubiquitination of NLRP3, leading NLRP3 to a "closed" inactive conformation. Intraperitoneal administration of triptolidiol significantly attenuated LPS-induced acute lung injury and lethal septic shock. Triptolidiol is a novel NLRP3 inhibitor that regulates inflammasome assembly and activation by decreasing K63-linked ubiquitination. Triptolidiol has novel structural features that make it distinct from reported NLRP3 inhibitors and represents a viable therapeutic lead for inflammatory diseases.

P23-13 Hexavalent chromium exposure induces lung injury via activation of NLRP3 and AIM2 inflammasomes in lung of rats

P23-13 Hexavalent chromium exposure induces lung injury via activation of NLRP3 and AIM2 inflammasomes in lung of rats

Gasdermin D and Gasdermin E Are Dispensable for Silica-Mediated IL-1β Secretion from Mouse Macrophages.

Silica crystals activate the NLRP3 inflammasome in macrophages, resulting in the caspase-1-dependent secretion of the proinflammatory cytokine IL-1β. Caspase-1-mediated cleavage of gasdermin D (GSDMD) triggers the formation of GSDMD pores, which drive pyroptotic cell death and facilitate the rapid release of IL-1β. However, the role of GSDMD in silica-induced lung injury is unclear. In this study, we show that although silica-induced lung injury is dependent on the inflammasome adaptor ASC and IL-1R1 signaling, GSDMD is dispensable for acute lung injury. Although the early rapid secretion of IL-1β in response to ATP and nigericin was GSDMD dependent, GSDMD was not required for IL-1β release at later time points. Similarly, secretion of IL-1β from macrophages in response to silica and alum proceeded in a GSDMD-independent manner. We further found that gasdermin E did not contribute to macrophage IL-1β secretion in the absence of GSDMD invitro and was also not necessary for silica-induced acute lung injury invivo. These findings demonstrate that GSDMD and gasdermin E are dispensable for IL-1β secretion in response to silica invitro and in silica-induced acute lung injury invivo.

E3 ubiquitin ligase MARCH1 reduces inflammation and pyroptosis in cerebral ischemia-reperfusion injury via PCSK9 downregulation.

Pyroptosis has been regarded as caspase-1-mediated monocyte death that induces inflammation, showing a critical and detrimental role in the development of cerebral ischemia-reperfusion injury (IRI). MARCH1 is an E3 ubiquitin ligase that exerts potential anti-inflammatory functions. Therefore, the study probed into the significance of MARCH1 in inflammation and pyroptosis elicited by cerebral IRI. Middle cerebral artery occlusion/reperfusion (MCAO/R)-treated mice and oxygen glucose deprivation/reoxygenation (OGD/R)-treated hippocampal neurons were established to simulate cerebral IRI in vivo and in vitro. MARCH1 and PCSK9 expression was tested in MCAO/R-operated mice, and their interaction was identified by means of the cycloheximide assay and co-immunoprecipitation. The functional roles of MARCH1 and PCSK9 in cerebral IRI were subsequently determined by examining the neurological function, brain tissue changes, neuronal viability, inflammation, and pyroptosis through ectopic expression and knockdown experiments. PCSK9 expression was increased in the brain tissues of MCAO/R mice, while PCSK9 knockdown reduced brain damage and neurological deficits. Additionally, inflammation and pyroptosis were inhibited in OGD/R-exposed hippocampal neurons upon PCSK9 knockdown, accompanied by LDLR upregulation and NLRP3 inflammasome inactivation. Mechanistic experiments revealed that MARCH1 mediated ubiquitination and degradation of PCSK9, lowering PCSK9 protein expression. Furthermore, it was demonstrated that MARCH1 suppressed inflammation and pyroptosis after cerebral IRI by downregulating PCSK9 both in vivo and in vitro. Taken together, the present study demonstrate the protective effect of MARCH1 against cerebral IRI through PCSK9 downregulation, which might contribute to the discovery of new therapies for improving cerebral IRI.

P18-03 Ferroptosis mediated by mtROS is involved in the Ag2Se QDs induced NLRP3 inflammasome activation in BV2 cells

P18-03 Ferroptosis mediated by mtROS is involved in the Ag2Se QDs induced NLRP3 inflammasome activation in BV2 cells

Targeting ceramide-induced microglial pyroptosis: Icariin is a promising therapeutic therapy for Alzheimer's disease

Alzheimer’s disease (AD), a progressive dementia, is one of the most common neurodegenerative diseases. Clinical trial results of amyloid-β (Aβ) and tau regulators based on the pretext of straightforward amyloid and tau immunotherapy were disappointing. There are currently no effective strategies for slowing the progression of AD. Herein, we spotlight the dysregulation of lipid metabolism, particularly the elevation of ceramides (Cers), as a critical yet underexplored facet of AD pathogenesis. Our study delineates the role of Cers in promoting microglial pyroptosis, a form of programmed cell death distinct from apoptosis and necroptosis, characterized by cellular swelling, and membrane rupture mediated by the NLRP3 inflammasome pathway. Utilizing both in vivo experiments with APP/PS1 transgenic mice and in vitro assays with BV-2 microglial cells, we investigate the activation of microglial pyroptosis by Cers and its inhibition by Icariin (ICA), a flavonoid with known antioxidant and anti-inflammatory properties. Our findings reveal a significant increase in Cers levels and pyroptosis markers (NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain, caspase-1, gasdermin D, and interleukin-18) in the brains of AD model mice, indicating a direct involvement of Cers in AD pathology through the induction of microglial pyroptosis. Conversely, ICA treatment effectively reduces these pyroptotic markers and Cer levels, thereby attenuating microglial pyroptosis and suggesting a novel therapeutic mechanism of action against AD. This study not only advances our understanding of the pathogenic role of Cers in AD but also introduces ICA as a promising candidate for AD therapy, capable of mitigating neuroinflammation and pyroptosis through the COX2-NLRP3 inflammasome-GSDMD axis. Our results pave the way for further exploration of Cer metabolism disorders in neurodegenerative diseases and highlight the therapeutic potential of targeting microglial pyroptosis in AD.

Characterizing placental NLRP3 inflammasome and lipidome dynamics: Insights from glucose, metformin, and LPS exposure in placental explants

Characterizing placental NLRP3 inflammasome and lipidome dynamics: Insights from glucose, metformin, and LPS exposure in placental explants

Butyrate and propionate are microbial danger signals that activate the NLRP3 inflammasome in human macrophages upon TLR stimulation

Short-chain fatty acids (SCFAs) are immunomodulatory compounds produced by the microbiome through dietary fiber fermentation. Although generally considered beneficial for gut health, patients suffering from inflammatory bowel disease (IBD) display poor tolerance to fiber-rich diets, suggesting that SCFAs may have contrary effects under inflammatory conditions. To investigate this, we examined the effect of SCFAs on human macrophages in the presence of Toll-like receptor (TLR) agonists. In contrast to anti-inflammatory effects under steady-state conditions, we found that butyrate and propionate activated the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in the presence of TLR agonists. Mechanistically, these SCFAs prevented transcription of FLICE-like inhibitory protein (cFLIP) and interleukin-10 (IL-10) through histone deacetylase (HDAC) inhibition, triggering caspase-8-dependent NLRP3 inflammasome activation. SCFA-driven NLRP3 activation was potassium efflux independent and did not result in cell death but rather triggered hyperactivation and IL-1β release. Our findings demonstrate that butyrate and propionate are bacterially derived danger signals that regulate NLRP3 inflammasome activation through epigenetic modulation of the inflammatory response.