[Impact of chaperone-mediated autophagy on bilirubin-induced damage of mouse microglial cells]. / åˆ†å­ä¼´ä¾£ä»‹å¯¼çš„è‡ªå™¬å¯¹èƒ†çº¢ç´ è¯±å¯¼çš„å°é¼ å°èƒ¶è´¨ç»†èƒžæŸä¼¤çš„å½±å“.

OBJECTIVES: To investigate the effect of chaperone-mediated autophagy (CMA) on the damage of mouse microglial BV2 cells induce by unconjugated bilirubin (UCB). METHODS: The BV2 cell experiments were divided into two parts. (1) For the CMA activation experiment: control group (treated with an equal volume of dimethyl sulfoxide), QX77 group (treated with 20 µmol/L QX77 for 24 hours), UCB group (treated with 40 µmol/L UCB for 24 hours), and UCB+QX77 group (treated with both 20 µmol/L QX77 and 40 µmol/L UCB for 24 hours). (2) For the cell transfection experiment: LAMP2A silencing control group (treated with an equal volume of dimethyl sulfoxide), LAMP2A silencing control+UCB group (treated with 40 µmol/L UCB for 24 hours), LAMP2A silencing group (treated with an equal volume of dimethyl sulfoxide), and LAMP2A silencing+UCB group (treated with 40 µmol/L UCB for 24 hours). The cell viability was assessed using the modified MTT method. The expression levels of p65, nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), and cysteinyl aspartate specific proteinase-1 (caspase-1) were detected by Western blot. The relative mRNA expression levels of the inflammatory cytokines interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α (TNF-α) were determined by real-time quantitative polymerase chain reaction. Levels of IL-6 and TNF-α in the cell culture supernatant were measured using ELISA. The co-localization of heat shock cognate protein 70 with p65 and NLRP3 was detected by immunofluorescence. RESULTS: Compared to the UCB group, the cell viability in the UCB+QX77 group increased, and the expression levels of inflammation-related proteins p65, NLRP3, and caspase-1, as well as the mRNA relative expression levels of IL-1ß, IL-6, and TNF-α and levels of IL-6 and TNF-α decreased (P<0.05). Compared to the control group, there was co-localization of heat shock cognate protein 70 with p65 and NLRP3 in both the UCB and UCB+QX77 groups. After silencing the LAMP2A gene, compared to the LAMP2A silencing control+UCB group, the LAMP2A silencing+UCB group showed increased expression levels of inflammation-related proteins p65, NLRP3, and caspase-1, as well as increased mRNA relative expression levels of IL-1ß, IL-6, and TNF-α and levels of IL-6 and TNF-α (P<0.05). CONCLUSIONS: CMA is inhibited in UCB-induced BV2 cell damage, and activating CMA may reduce p65 and NLRP3 protein levels, suppress inflammatory responses, and counteract bilirubin neurotoxicity.

Vitamin D Status Modestly Regulates NOD-Like Receptor Family with a Pyrin Domain 3 Inflammasome and Interleukin Profiles among Arab Adults.

Vitamin D (VD) deficiency has been associated with inflammation and dysregulation of the immune system. The NLRP3 inflammasome, a critical immune response component, plays a pivotal role in developing inflammatory diseases. VD hinders NLRP3 inflammasome activation and thus exerts anti-inflammatory effects. This study aimed to analyze the effect of VD deficiency on circulating levels of NLRP3 inflammasomes (NLRP3 and caspase-1) and associated interleukins (IL-1α, IL-1ß, IL-18, IL-33 and IL-37) in Saudi adults. Methods: A total of 338 Saudi adults (128 males and 210 females) (mean age = 41.2 ± 9.1 years and mean BMI 31.2 ± 6.5 kg/m2) were included. Overnight-fasting serum samples were collected. Participants were stratified according to their VD status. Serum levels of NLRP3 inflammasomes and interleukins of interest were assessed using commercially available immuno-assays. Individuals with VD deficiency had significantly lower mean 25(OH)D levels than those with a normal VD status (29.3 nmol/L vs. 74.2 nmol/L, p < 0.001). The NLRP3 levels were higher in the VD-deficient group than their VD-sufficient counterparts (0.18 vs. 0.16, p = 0.01). Significant inverse associations were observed between NLRP3 levels with age (r = -0.20, p = 0.003) and BMI (r = -0.17, p = 0.01). Stepwise regression analysis identified insulin (ß = 0.38, p = 0.005) and NLRP3 (ß = -1.33, p = 0.03) as significant predictors of VD status, explaining 18.3% of the variance. The findings suggest that the VD status modestly regulates NLRP3 inflammasome and interleukin activities. This may provide novel insights into the pathogenesis and management of inflammatory disorders.

NLRP3 and cancer: Pathogenesis and therapeutic opportunities.

More than a decade ago IL-1 blockade was suggested as an add-on therapy for the treatment of cancer. This proposal was based on the overall safety record of anti-IL-1 biologics and the anti-tumor properties of IL-1 blockade in animal models of cancer. Today, a new frontier in IL-1 activity regulation has developed with several orally active NLRP3 inhibitors currently in clinical trials, including cancer. Despite an increasing body of evidence suggesting a role of NLRP3 and IL-1-mediated inflammation driving cancer initiation, immunosuppression, growth, and metastasis, NLRP3 activation in cancer remains controversial. In this review, we discuss the recent advances in the understanding of NLRP3 activation in cancer. Further, we discuss the current opportunities for NLRP3 inhibition in cancer intervention with novel small molecules.

Discovery of Clinical Candidate NT-0796, a Brain-Penetrant and Highly Potent NLRP3 Inflammasome Inhibitor for Neuroinflammatory Disorders.

The NLRP3 inflammasome is a component of the innate immune system involved in the production of proinflammatory cytokines. Neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis, have been shown to have a component driven by NLRP3 inflammasome activation. Diseases such as these with large unmet medical needs have resulted in an interest in inhibiting the NLRP3 inflammasome as a potential pharmacological treatment, but to date, no marketed drugs specifically targeting NLRP3 have been approved. Furthermore, the requirement for CNS-penetrant molecules adds additional complexity to the search for NLRP3 inflammasome inhibitors suitable for clinical investigation of neuroinflammatory disorders. We designed a series of ester-substituted carbamate compounds as selective NLRP3 inflammasome inhibitors, leading to NT-0796, an isopropyl ester that undergoes intracellular conversion to NDT-19795, the carboxylic acid active species. NT-0796 was shown to be a potent and selective NLRP3 inflammasome inhibitor with demonstrated in vivo brain penetration.

PM2.5 exposure aggravates acute liver injury by creating an inflammatory microenvironment through Kupffer cell.

AIM: This work aimed to investigate the impact of PM2.5 exposure on acute liver injury METHODS: C57BL/6 mice were used to examine the hepatic histopathological changes in PM2.5-exposed mice, as well as in CCl4-mediated acute liver injury mice after long-term exposure to PM2.5. During in vitro experiments, Kupffer cells were detected for M1 polarization level after treating with PM2.5, and the activation level of NLRP3 inflammasomes were assessed. RESULTS: According to our findings, PM2.5 can induce M1 polarization of Kupffer cells in the liver to create an inflammatory microenvironment. Long-term exposure to PM2.5 can aggravate acute liver injury in mice. Treatment with MCC950, an NLRP3 inhibitor, can inhibit the effect of PM2.5. As demonstrated by in vitro analysis, PM2.5 can promote M1 polarization of Kupffer cells. CONCLUSION: As suggested by our results, long-term exposure to PM2.5 can create an inflammatory microenvironment to aggravate mouse acute liver injury. The effect is related to NLRP3-mediated M1 polarization in Kupffer cells.

MCC950 in the treatment of NLRP3-mediated inflammatory diseases: Latest evidence and therapeutic outcomes.

Evidence suggests that various innate immune system components are involved in pathological inflammatory conditions. Among these components, the NLR family pyrin domain containing 3 (NLRP3) as an inflammasome can participate in destructive inflammatory responses by inducing the production of the active form of inflammatory cytokines. The NLRP3 could be involved in the pathogenesis of several inflammatory and autoimmune diseases such as type 2 diabetes mellitus, multiple sclerosis (MS), atherosclerosis, Alzheimer's disease (AD), cryopyrin-associated periodic syndrome (CAPS), and infectious diseases. Therefore, the inhibition of NLRP3 can be a useful treatment option for inflammatory diseases. In this regard, MCC950, as a small molecule, is capable of inhibiting NLRP3 and, following inhibition of NLRP3, production of interleukin-1ß (IL-1ß) and IL-18 as pro-inflammatory cytokines reduced. Interestingly, the MCC950 can inhibit NLRP3 but no other inflammasomes such as NLRP1 and NLR family CARD domain containing 4 (NLRC4). This review summarized the structure and mechanism of action of MCC950 in the control of NLRP3-dependent inflammation and the role of MCC950 in the treatment of NLRP3-mediated inflammatory diseases based on the latest studies.

The role of caspase-1, caspase-4 and NLRP3 in regulating the host cell response evoked by uropathogenic Escherichia coli.

The inflammasome-associated proteins caspase-1, caspase-4 and NLRP3 have been emphasised to be essential in the host cell response during urinary tract infection (UTI) by regulating IL-1ß release. Our aim was to investigate how the inflammasome-associated proteins regulate the cell response of bladder epithelial cells during infection with uropathogenic Escherichia coli (UPEC). Human bladder epithelial cells (5637) and CRISPR/Cas9 generated caspase-1, caspase-4 and NLRP3 knockdown cells were stimulated with the UPEC strain CFT073. Using Olink proteomics and real time RT-PCR, we showed that caspase-1, caspase-4 and NLRP3 are vital for the expression of many inflammatory genes and proteins from bladder epithelial cells. When investigating the effect of inflammasome-associated proteins on neutrophils, we found that conditioned medium from UPEC-infected caspase-4 knockdown cells significantly increased phagocytosis of CFT073 and significantly decreased ROS production from neutrophils. In contrast, conditioned medium from UPEC-infected NLRP3 knockdown cells significantly decreased the phagocytosis of CFT073 and significantly increased the ROS production from neutrophils. In conclusion, we showed that the inflammasome-associated proteins contribute to the host cell response during UPEC infection.

TRIMs: Generalists Regulating the NLRP3 Inflammasome Signaling Pathway.

Inflammation is a double-edged sword. The moderate inflammatory response is a fundamental defense mechanism produced by the body's resistance to dangerous stimuli and a repair process of the body itself. Increasing studies have confirmed that the overactivation of the inflammasome is involved in the occurrence and development of inflammatory diseases. Strictly controlling the overactivation of the inflammasome and preventing excessive inflammatory response have always been the research focus on inflammatory diseases. However, the endogenous regulatory mechanism of inflammasome is not completely clear. The tripartite motif (TRIM) protein is one of the members of E3 ligases in the process of ubiquitination. The universality and importance of the functions of TRIM members are recognized, including the regulation of inflammatory response. This article will focus on research on the relationship between TRIMs and NLRP3 Inflammasome, which may help us make some references for future related research and the discovery of treatment methods.

Trimetazidine affects pyroptosis by targeting GSDMD in myocardial ischemia/reperfusion injury.

OBJECTIVE: Trimetazidine (TMZ) exerts a strong inhibitory effect on ischemia/reperfusion (I/R) injury. Inflammation plays a key role in I/R injury. We hypothesized that TMZ may protect cardiomyocytes from I/R injury by inhibiting inflammation. METHODS: The left anterior descending coronary artery was ligated for 30 min followed by 6 h of reperfusion to establish a model of I/R injury. H9c2 cardiomyocytes were subjected to 2 h of hypoxia and 3 h of normoxic conditions to establish a model of hypoxia/reoxygenation (H/R) injury. We monitored the change in pyroptosis by performing Western blot analysis, microscopy and ELISA. RESULTS: I/R and H/R treatment stimulated gasdermin D-N domain (GSDMD-N) expression in cardiomyocytes (sham onefold vs. I/R 2.5-fold; control onefold vs. H/R 2.0-fold). Moreover, TMZ increased the viability of H9c2 cardiomyocytes subjected to H/R treatment (H/R 65.0% vs. H/R + TMZ 85.3%) and reduced the infarct size in vivo (I/R 47.0% vs. I/R + TMZ 28.3%). H/R and I/R treatment increased the levels of TLR4, MyD88, phospho-NF-κB p65 and the NLRP3 inflammasome; however, TMZ reduced the expression of these proteins. Additionally, TMZ inhibited noncanonical inflammasome signaling induced by I/R injury. CONCLUSIONS: In summary, TMZ alleviated pyroptosis induced by myocardial I/R injury through the TLR4/MyD88/NF-κB/NLRP3 inflammasome pathway. Therefore, TMZ represents an alternative treatment for myocardial I/R injury.

NOD-like receptor protein 3 activation causes spontaneous inflammation and fibrosis that mimics human NASH.

BACKGROUND AND AIMS: The NOD-like receptor protein 3 (NLRP3) inflammasome is a central contributor to human acute and chronic liver disease, yet the molecular and cellular mechanisms by which its activation precipitates injury remain incompletely understood. Here, we present single cell transcriptomic profiling of livers from a global transgenic tamoxifen-inducible constitutively activated Nlrp3A350V mutant mouse, and we investigate the changes in parenchymal and nonparenchymal liver cell gene expression that accompany inflammation and fibrosis. APPROACH AND RESULTS: Our results demonstrate that NLRP3 activation causes chronic extramedullary myelopoiesis marked by myeloid progenitors that differentiate into proinflammatory neutrophils, monocytes, and monocyte-derived macrophages. We observed prominent neutrophil infiltrates with increased Ly6gHI and Ly6gINT cells exhibiting transcriptomic signatures of granulopoiesis typically found in the bone marrow. This was accompanied by a marked increase in Ly6cHI monocytes differentiating into monocyte-derived macrophages that express transcriptional programs similar to macrophages of NASH models. NLRP3 activation also down-regulated metabolic pathways in hepatocytes and shifted hepatic stellate cells toward an activated profibrotic state based on expression of collagen and extracellular matrix regulatory genes. CONCLUSIONS: These results define the single cell transcriptomes underlying hepatic inflammation and fibrosis precipitated by NLRP3 activation. Clinically, our data support the notion that NLRP3-induced mechanisms should be explored as therapeutic target in NASH-like inflammation.

PM2.5 exposure inducing ATP alteration links with NLRP3 inflammasome activation.

Fine particulate matter (PM2.5) has been the primary air pollutant and the fourth leading risk factor for disease and death in the world. Exposure to PM2.5 is related to activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, but the mechanism of PM2.5 affecting the NLRP3 inflammasome is still unclear. Previous studies have shown that PM2.5 can cause alterations in adenosine triphosphate (ATP), and an increase in extracellular ATP and a decrease in intracellular ATP can trigger the activation process of the NLRP3 inflammasome. Therefore, we emphasize that ATP changes may be the central link and key mechanism of PM2.5 exposure that activates the NLRP3 inflammasome. This review briefly elucidates and summarizes how PM2.5 acts on ATP and subsequently further impacts the NLRP3 inflammasome. Investigation of ATP changes due to exposure to PM2.5 may be essential to regulate NLRP3 inflammasome activation and treat inflammation-related diseases such as coronavirus disease 2019 (COVID-19).

Activation of the NLRP3 inflammasome by RAC1 mediates a new mechanism in diabetic nephropathy.

OBJECTIVE: Inflammation is central to the development and progression of diabetic nephropathy (DN). Although the exact mechanisms of inflammation in the kidney have not been well elucidated, pyrin domain containing 3 (NLRP3) inflammasome activation is involved in the onset and progression of DN. Here, we investigated the underlying regulatory mechanisms of hyperglycaemia-induced NLRP3 inflammasome activation in the kidney. METHODS: HEK293T cells received high glucose, and the cell proliferation and apoptosis were detected. Biochemical indicators in db/db mice were tested by kits, and the morphological changes in the kidney were observed using staining methods and transmission electron microscopy. The interaction of Ras-related C3 botulinum toxin substrate 1 (RAC1) and NLRP3 inflammasome in cells and in mice was assessed by co-immunoprecipitation (Co-IP) and immunofluorescence. Expression of all proteins was examined by western blotting and immunohistochemistry. In additional, the directly combination of RAC1 and NLRP3 was evaluated by GST Pulldown. RESULTS: High-glucose and hyperglycaemia conditions resulted in Ras-related C3 botulinum toxin substrate 1 (RAC1) and NLRP3 inflammasome interactions in cells and in mice. Additionally, RAC1 promoted NLRP3 inflammasome activation and then induced cell damage, and morphological and functional abnormalities in the kidney. We also observed that RAC1 activates the NLRP3 inflammasome by directly binding to NLRP3. CONCLUSION: In the present study, we confirmed that RAC1 binding to NLRP3 is sufficient to activate the NLRP3 inflammasome in the kidney and accelerate DN pathological processes. These results elucidate the upstream cellular and molecular mechanisms of NLRP3 inflammasome activation and provide new therapeutic strategies for the treatment of DN.

Acute Hyperglycemia Exacerbates Hemorrhagic Transformation after Embolic Stroke and Reperfusion with tPA: A Possible Role of TXNIP-NLRP3 Inflammasome.

OBJECTIVES: Acute hyperglycemia (HG) exacerbates reperfusion injury after stroke. Our recent studies showed that acute HG upregulates thioredoxin-interacting protein (TXNIP) expression, which in turn induces inflammation and neurovascular damage in a suture model of ischemic stroke. The aim of the present study was to investigate the effect of acute HG on TXNIP-associated neurovascular damage, in a more clinically relevant murine model of embolic stroke and intravenous tissue plasminogen activator (IV-tPA) reperfusion. MATERIALS AND METHODS: HG was induced in adult male mice, by intraperitoneal injection of 20% glucose. This was followed by embolic middle cerebral artery occlusion (eMCAO), with or without IV-tPA (10 mg/kg) given 3 h post embolization. Brain infarction, edema, hemoglobin content, expression of matrix metalloproteinase (MMP-9), vascular endothelial growth factor A (VEGFA), tight junction proteins (claudin-5, occluding, and zonula occludens-1), TXNIP, and NOD-like receptor protein3 (NLRP3)-inflammasome activation were evaluated at 24 h after eMCAO. RESULTS: HG alone significantly increased TXNIP in the brain after eMCAO, and this was associated with exacerbated hemorrhagic transformation (HT; as measured by hemoglobin content). IV-tPA in HG conditions showed a trend to decrease infarct volume, but worsened HT after eMCAO, suggesting that HG reduces the therapeutic efficacy of IV-tPA. Further, HG and tPA-reperfusion did not show significant differences in expression of MMP-9, VEGFA, junction proteins, and NLRP3 inflammasome activation between the groups. CONCLUSION: The current findings suggest a potential role for TXNIP in the occurrence of HT in hyperglycemic conditions following eMCAO. Further studies are needed to understand the precise role of vascular TXNIP on HG/tPA-induced neurovascular damage after stroke.

Purinergic Signaling in the Regulation of Gout Flare and Resolution.

Gout flares require monosodium urate (MSU) to activate the NLRP3 inflammasome and secrete sufficient IL-1ß. However, MSU alone is not sufficient to cause a flare. This is supported by the evidence that most patients with hyperuricemia do not develop gout throughout their lives. Recent studies have shown that, besides MSU, various purine metabolites, including adenosine triphosphate, adenosine diphosphate, and adenosine bind to different purine receptors for regulating IL-1ß secretion implicated in the pathogenesis of gout flares. Purine metabolites such as adenosine triphosphate mainly activate the NLRP3 inflammasome through P2X ion channel receptors, which stimulates IL-1ß secretion and induces gout flares, while some purine metabolites such as adenosine diphosphate and adenosine mainly act on the G protein-coupled receptors exerting pro-inflammatory or anti-inflammatory effects to regulate the onset and resolution of a gout flare. Given that the purine signaling pathway exerts different regulatory effects on inflammation and that, during the inflammatory process of a gout flare, an altered expression of purine metabolites and their receptors was observed in response to the changes in the internal environment. Thus, the purine signaling pathway is involved in regulating gout flare and resolution. This study was conducted to review and elucidate the role of various purine metabolites and purinergic receptors during the process.

IL-38 Alleviates Inflammation in Sepsis in Mice by Inhibiting Macrophage Apoptosis and Activation of the NLRP3 Inflammasome.

Interleukin- (IL-) 38 is an emerging cytokine with multiple functions involved in infection and immunity. However, the potential role of IL-38 in the host immune response during sepsis remains elusive. Herein, we investigated if macrophages in septic mice express IL-38, the molecular mechanisms behind its expression, and the downstream effects of its expression. In mouse peritoneal macrophages, lipopolysaccharide (LPS) upregulated IL-38 and its receptor IL-36R, and the resulting IL-38 shifted macrophages from a M1 to M2 phenotype. Moreover, exposure to IL-38 alone was sufficient to inhibit macrophage apoptosis and LPS-driven activation of the NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) inflammasome. These effects were partly abrogated by IL-38 downregulation. In septic mice, IL-38 markedly lowered serum concentrations of proinflammatory cytokines and greatly improved survival. Conversely, IL-38 blockade aggravated their mortality. Collectively, these findings present IL-38 as a potent immune modulator that restrains the inflammatory response by suppressing macrophage apoptosis and activation of the NLRP3 inflammasome. IL-38 may help protect organs from sepsis-related injury.

Inhibition of the PERK/TXNIP/NLRP3 Axis by Baicalin Reduces NLRP3 Inflammasome-Mediated Pyroptosis in Macrophages Infected with Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb) remains a significant threat to global health as it induces granuloma and systemic inflammatory responses during active tuberculosis. Mtb can induce macrophage pyroptosis, leading to the release of IL-1ß and tissue damage, promoting its spread. Here, we established an in vitro Mtb-infected macrophage model to seek an effective antipyroptosis agent. Baicalin, isolated from Radix Scutellariae, was found to reduce pyroptosis in Mtb-infected macrophages. Baicalin could inhibit activation of the PERK/eIF2α pathway and thus downregulates TXNIP expression and subsequently reduces activation of the NLRP3 inflammasome, resulting in reduced pyroptosis in Mtb-infected macrophages. In conclusion, baicalin reduced pyroptosis by inhibiting the PERK/TXNIP/NLRP3 axis and might thus be a new adjuvant host-directed therapy (HDT) drug.

The Role of HDAC6 in Autophagy and NLRP3 Inflammasome.

Autophagy fights against harmful stimuli and degrades cytosolic macromolecules, organelles, and intracellular pathogens. Autophagy dysfunction is associated with many diseases, including infectious and inflammatory diseases. Recent studies have identified the critical role of the NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasomes activation in the innate immune system, which mediates the secretion of proinflammatory cytokines IL-1ß/IL-18 and cleaves Gasdermin D to induce pyroptosis in response to pathogenic and sterile stimuli. Accumulating evidence has highlighted the crosstalk between autophagy and NLRP3 inflammasome in multifaceted ways to influence host defense and inflammation. However, the underlying mechanisms require further clarification. Histone deacetylase 6 (HDAC6) is a class IIb deacetylase among the 18 mammalian HDACs, which mainly localizes in the cytoplasm. It is involved in two functional deacetylase domains and a ubiquitin-binding zinc finger domain (ZnF-BUZ). Due to its unique structure, HDAC6 regulates various physiological processes, including autophagy and NLRP3 inflammasome, and may play a role in the crosstalk between them. In this review, we provide insight into the mechanisms by which HDAC6 regulates autophagy and NLRP3 inflammasome and we explored the possibility and challenges of HDAC6 in the crosstalk between autophagy and NLRP3 inflammasome. Finally, we discuss HDAC6 inhibitors as a potential therapeutic approach targeting either autophagy or NLRP3 inflammasome as an anti-inflammatory strategy, although further clarification is required regarding their crosstalk.

Bacteroides fragilis restricts colitis-associated cancer via negative regulation of the NLRP3 axis.

Patients with persistent ulcerative colitis (UC) are at a higher risk of developing colitis-associated cancer (CAC). Previous studies have reported that intestinal microbiota disturbance plays an important role in the process of CAC development in patients with UC, indicating that targeted intervention of intestinal microbiota and its metabolites may be a potential therapeutic strategy. Gut microbiota in the process of colorectal cancer development in UC patients was analyzed using the gutMEGA database and verified in fecal samples. The abundance of Bacteroides fragilis reduced significantly in the process of colitis associated cancer development. Broad-spectrum antibiotics (BSAB) intervene with the intestinal microbiota of mice and accelerate the process of colon cancer development. However, gavage transplantation with B. fragilis can effectively reverse the effects of BSAB. In the intestinal tract, B. fragilis promotes the secretion of short-chain fatty acids (SCFAs). Subsequently, SCFAs, especially butyrate, negatively regulate the inflammatory signaling pathway mediated by NLRP3 to inhibit the activation of macrophages and the secretion of proinflammatory mediators such as IL-18 and IL-1ß, reducing the level of intestinal inflammation and restricting CAC development. In conclusion, colonization with B. fragilis has been shown to be effective in ameliorating intestinal epithelial damage caused by chronic inflammation and preventing the development of colonic tumors. Thus, it can be a therapeutic intervention strategy with good clinical application prospects.

The key role of NLRP3 and STING in APOL1-associated podocytopathy.

Coding variants in apolipoprotein L1 (APOL1), termed G1 and G2, can explain most excess kidney disease risk in African Americans; however, the molecular pathways of APOL1-induced kidney dysfunction remain poorly understood. Here, we report that expression of G2 APOL1 in the podocytes of Nphs1rtTA/TRE-G2APOL1 (G2APOL1) mice leads to early activation of the cytosolic nucleotide sensor, stimulator of interferon genes (STING), and the NLR family pyrin domain-containing 3 (NLRP3) inflammasome. STING and NLRP3 expression was increased in podocytes from patients with high-risk APOL1 genotypes, and expression of APOL1 correlated with caspase-1 and gasdermin D (GSDMD) levels. To demonstrate the role of NLRP3 and STING in APOL1-associated kidney disease, we generated transgenic mice with the G2 APOL1 risk variant and genetic deletion of Nlrp3 (G2APOL1/Nlrp3 KO), Gsdmd (G2APOL1/Gsdmd KO), and STING (G2APOL1/STING KO). Knockout mice displayed marked reduction in albuminuria, azotemia, and kidney fibrosis compared with G2APOL1 mice. To evaluate the therapeutic potential of targeting NLRP3, GSDMD, and STING, we treated mice with MCC950, disulfiram, and C176, potent and selective inhibitors of NLRP3, GSDMD, and STING, respectively. G2APOL1 mice treated with MCC950, disulfiram, and C176 showed lower albuminuria and improved kidney function even when inhibitor treatment was initiated after the development of albuminuria.

Neutrophils Facilitate Prolonged Inflammasome Response in the DAMP-Rich Inflammatory Milieu.

Aberrant inflammasome activation contributes to various chronic inflammatory diseases; however, pyroptosis of inflammasome-active cells promptly terminates local inflammasome response. Molecular mechanisms underlying prolonged inflammasome signaling thus require further elucidation. Here, we report that neutrophil-specific resistance to pyroptosis and NLRP3 desensitization can facilitate sustained inflammasome response and interleukin-1ß secretion. Unlike macrophages, inflammasome-activated neutrophils did not undergo pyroptosis, indicated by using in vitro cell-based assay and in vivo mouse model. Intriguingly, danger-associated molecular patterns (DAMP)-rich milieu in the inflammatory region significantly abrogated NLRP3-activating potential of macrophages, but not of neutrophils. This macrophage-specific NLRP3 desensitization was associated with DAMP-induced mitochondrial depolarization that was not observed in neutrophils due to a lack of SARM1 expression. Indeed, valinomycin-induced compulsory mitochondrial depolarization in neutrophils restored inflammasome-dependent cell death and ATP-induced NLRP3 desensitization in neutrophils. Alongside prolonged inflammasome-activating potential, neutrophils predominantly secreted interleukin-1ß rather than other proinflammatory cytokines upon NLRP3 stimulation. Furthermore, inflammasome-activated neutrophils did not trigger efferocytosis-mediated M2 macrophage polarization essential for the initiation of inflammation resolution. Taken together, our results indicate that neutrophils can prolong inflammasome response via mitochondria-dependent resistance to NLRP3 desensitization and function as major interleukin-1ß-secreting cells in DAMP-rich inflammatory region.