NLRP3 Inflammasome Activation Research Articles

Structural properties of immune complexes formed by viral antigens and specific antibodies shape the inflammatory response of macrophages

Data on the course of viral infections revealed severe inflammation as a consequence of antiviral immune response. Despite extensive research, there are insufficient data on the role of innate immune cells in promoting inflammation mediated by immune complexes (IC) of viral antigens and their specific antibodies. Recently, we demonstrated that antigens of human polyomaviruses (PyVs) induce an inflammatory response in macrophages. Here, we investigated macrophage activation by IC. We used primary murine macrophages as a cell model, virus-like particles (VLPs) of PyV capsid protein as antigens, and a collection of murine monoclonal antibodies (mAbs) of IgG1, IgG2a, IgG2b subclasses. The inflammatory response was investigated by analysing inflammatory chemokines and activation of NLRP3 inflammasome. We observed a diverse pattern of chemokine secretion in macrophages treated with different IC compared to VLPs alone. To link IC properties with cell activation status, we characterised the IC by advanced optical and acoustic techniques. Ellipsometry provided precise real-time kinetics of mAb-antigen interactions, while quartz crystal microbalance measurements showed changes in conformation and viscoelastic properties during IC formation. These results revealed differences in mAb-antigen interaction and mAb binding parameters of the investigated IC. We found that IC-mediated cell activation depends more on IC characteristics, including mAb affinity, than on mAb affinity for the activating Fc receptor. IC formed by the highest affinity mAb showed a significant enhancement of inflammasome activation. This may explain the hyperinflammation related to viral infection and vaccination. Our findings demonstrate that IC promote the viral antigen-induced inflammatory response depending on antibody properties.

Metformin inhibits activation of NLRP3 inflammasome and inflammatory response in preeclamptic rats

Backgroud: It is widely acknowledged that Metformin (MET), an established medication for managing type 2 diabetes, possesses diverse pharmacological effects. This study aims to investigate the protective effects of MET against Nω-Nitro-L-arginine methyl ester (L-NAME)-induced preeclampsia (PE). MethodsSprague Dawley (SD) rats were exposed to 200 mg/kg L-NAME with or without prior MET treatment. Histopathological analysis was performed using Hematoxylin and Eosin staining. Serum levels of inflammatory, antiangiogenic, and angiogenic factors were quantified using ELISA kits. Immunohistochemistry (IHC) staining was employed to observe NLRP3 and IL-1β expressions in placental tissues. Western blot and Quantitative Real-Time PCR (q-PCR) analyses were conducted to assess protein and mRNA expressions of NLRP3, caspase-1, ASC, and IL-1β. ResultsWe found that MET could mitigate placental histopathological deterioration and improve pregnancy outcomes in L-NAME-induced PE rat models. MET not only suppressed L-NAME-induced elevation of antiangiogenic factors but also stimulated the production of pro-angiogenic factors. Additionally, MET treatment reversed the excessive inflammatory response induced by L-NAME. Furthermore, MET inhibited the activation of the NLRP3 inflammasome triggered by L-NAME, evidenced by the downregulation of NLRP3 expression, caspase-1, and IL-1β. ConclusionsMET demonstrates a protective effect against L-NAME-induced PE rats, potentially mediated through inhibition of the inflammatory response, downregulation of NLRP3 inflammasome expression in the placenta, and regulation of the balance between anti-angiogenic and pro-angiogenic factors.

BGP-15 alleviates LPS-induced depression-like behavior by promoting mitophagy

The high prevalence of major depressive disorder (MDD) frequently imposes severe constraints on psychosocial functioning and detrimentally impacts overall well-being. Despite the growing interest in the hypothesis of mitochondrial dysfunction, the precise mechanistic underpinnings and therapeutic strategies remain unclear and require further investigation. In this study, an MDD model was established in mice using lipopolysaccharide (LPS). Our research findings demonstrated that LPS exposure induced depressive-like behaviors and disrupted mitophagy by diminishing the mitochondrial levels of PINK1/Parkin in the brains of mice. Furthermore, LPS exposure evoked the activation of the NLRP3 inflammasome, accompanied by a notable elevation in the concentrations of pro-inflammatory factors (TNF-α, IL-1β, and IL-6). Additionally, neuronal apoptosis was stimulated through the JNK/p38 pathway. The administration of BGP-15 effectively nullified the impact of LPS, corresponding to the amelioration of depressive-like phenotypes and restoration of mitophagy, prevention of neuronal injury and inflammation, and suppression of reactive oxygen species (ROS)-mediated NLRP3 inflammasome activation. Furthermore, we elucidated the involvement of mitophagy in BGP-15-attenuated depressive-like behaviors using the inhibitors targeting autophagy (3-MA) and mitophagy (Mdivi-1). Notably, these inhibitors notably counteracted the antidepressant and anti-inflammatory effects exerted by BGP-15. Based on the research findings, it can be inferred that the antidepressant properties of BGP-15 in LPS-induced depressive-like behaviors could potentially be attributed to the involvement of the mitophagy pathway. These findings offer a potential novel therapeutic strategy for managing MDD.

Activation of the Nrf2/ARE signaling pathway ameliorates hyperlipidemia-induced renal tubular epithelial cell injury by inhibiting mtROS-mediated NLRP3 inflammasome activation.

Dyslipidemia is the most prevalent independent risk factor for patients with chronic kidney disease (CKD). Lipid-induced NLRP3 inflammasome activation in kidney-resident cells exacerbates renal injury by causing sterile inflammation. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that modulates the cellular redox balance; however, the exact role of Nrf2 signaling and its regulation of the NLRP3 inflammasome in hyperlipidemia-induced kidney injury are poorly understood. In this study, we demonstrated that activation of the mtROS-NLRP3 inflammasome pathway is a critical contributor to renal tubular epithelial cell (RTEC) apoptosis under hyperlipidemia. In addition, the Nrf2/ARE signaling pathway is activated in renal tubular epithelial cells under hyperlipidemia conditions both in vivo and in vitro, and Nrf2 silencing accelerated palmitic acid (PA)-induced mtROS production, mitochondrial injury, and NLRP3 inflammasome activation. However, the activation of Nrf2 with tBHQ ameliorated mtROS production, mitochondrial injury, NLRP3 inflammasome activation, and cell apoptosis in PA-induced HK-2 cells and in the kidneys of HFD-induced obese rats. Furthermore, mechanistic studies showed that the potential mechanism of Nrf2-induced NLRP3 inflammasome inhibition involved reducing mtROS generation. Taken together, our results demonstrate that the Nrf2/ARE signaling pathway attenuates hyperlipidemia-induced renal injury through its antioxidative and anti-inflammatory effects through the downregulation of mtROS-mediated NLRP3 inflammasome activation.

Protective Effect of Egg Yolk Lipids against Dextran Sulfate Sodium-Induced Colitis: The Key Role of Gut Microbiota and Short-Chain Fatty Acids.

Egg yolk lipids significantly alleviate dextran sulfate sodium (DSS)-induced colitis by inhibiting NLRP3 inflammasome, reversing gut microbiota dysbiosis, and increasing short chain fatty acids (SCFAs) concentrations. However, the role of gut microbiota and the relationship between SCFAs and NLRP3 inflammasome are still unknown. Here, this study confirms that antibiotic treatment abolishes the protective effect of egg yolk lipids on DSS-induced colonic inflammation, intestinal barrier damage, and lipopolysaccharide translocation. Fecal microbiota transplantation also supports that egg yolk lipids alleviate colitis in a gut microbiota-dependent manner. Then, the study investigates the relationship between SCFAs and NLRP3 inflammasome, and finds that SCFAs significantly suppress colitis via inhibiting colonic NLRP3 inflammasome activation and proinflammatory cytokines secretions (interleukin, IL)-1β and IL-18, and combined treatment of SCFAs and MCC950 (NLRP3 inhibitor) shows a better activity against colitis and NLRP3 inflammasome activation. Together, these findings provide positive evidence for gut microbiorta-SCFAs-NLRP3 axis as a novel target involving in the therapy of inflammatory bowel disease.

Inhibition of Panx1 reduces neuroinflammatory response and alleviates brain damage in septic mice

Objective: This study mainly investigates whether Pannexin 1 protein (i.e. Panx1) plays a role in the progression of brain injury in sepsis mice and its potential mechanisms. Methods: A total of 45 clean grade adult male C57BL/6 healthy mice were selected and divided into three groups using a random number table method, namely the sham group, the cecal ligation perforation (CLP) group, and the CBX pretreatment plus cecal ligation perforation (CBX+CLP) group, with 15 mice in each group. Excluding the Sham group, the remaining two groups of study mice were used to prepare sepsis brain injury models using the CLP method. The CBX+CLP group was injected into the lateral ventricles of both sides of the mouse half an hour before the modeling process, with a total amount of 1 μL CBX, which was injected into the bilateral lateral ventricles of the other two groups of mice with the same dose of physiological saline solution. 24 hours after the completion of modeling, three groups of mice were evaluated for neurological behavior. Subsequently, all mice were euthanized. After the cardiac perfusion phase, brain tissue of the mice was taken to observe the pathological damage of the hippocampal tissue. The effective content of IL-1β and TNF‐α in the mouse's hippocampal tissue was measured, and the expression of Panx1 protein, Caspase-1, NLRP3 protein, as well as NLRP3, Panx1, Caspase-1, TNF‐α, IL-1β were measured the mRNA of corresponds to its expression status. Results: Compared with Sham group mice, the neurobehavioral score of CLP group mice significantly decreased, and the pathological damage degree of hippocampal neurons in mice was significant. The expression levels of inflammatory factors IL-1β and TNF‐α were increased, and the corresponding expression levels of Panx1, NLRP3, Caspase-1 proteins and mRNA were increased. The mRNA expression levels of inflammatory factors IL-1β and TNF were also increased (P<0 05), compared to the CLP group mice, the CBX+CLP group mice showed an increase in neurobehavioral scores, a reduction in pathological damage to hippocampal tissue, a decrease in the expression of inflammatory factors IL-1β and TNF‐α, a decrease in the expression levels of NLRP3, Panx1, Caspase-1 proteins, and corresponding mRNA, and a corresponding decrease in the mRNA expression of the two inflammatory factors (P<0 05). Conclusion: Inhibiting Panx1 can reduce the degree of neural inflammatory response, thereby improving brain damage in sepsis mice, which may be related to the limited activation of NLRP3 inflammasomes.

ML365 ameliorates postoperative cognitive impairment in aged mice by inhibiting NLRP3 inflammasome activation in the hippocampus

The aim of this study was to examine the effects of ML365, a two-pore potassium channel (K2P) inhibitor, on postoperative cognitive impairment (POCD). A mouse model of POCD was constructed by subjecting aged C57BL/6 mice to exploratory laparotomy. Changes in cognitive function were assessed using the Morris water maze test. Western blotting and qPCR were used to detect hippocampal NLRP3, Caspase-1 and IL-1β expression levels on days 3 and 7 post-surgery. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) expression level was also assessed by western blotting. Pathological changes and nerve damage in the hippocampal CA1 and CA3 regions were detected by H&E staining, while the concentration of malondialdehyde (MDA) in the plasma was measured. We found that pretreatment with ML365 (administered intraperitoneally at a dose of 10 mg/kg) 30 min prior to exploratory laparotomy effectively ameliorated POCD in mice. ML365 pretreatment also reduced NLRP3, Caspase-1, ASC and IL-1β expression levels in the hippocampus, improved POCD-induced pathological changes in the hippocampal CA1 and CA3 areas of aged mice, and decreased levels of plasma MDA and oxidative stress. Together, our findings indicate that ML365 can alleviate POCD in mice by inhibiting NLRP3 inflammasome activation in the hippocampus.

Luteolin, apigenin, and chrysin inhibit lipotoxicity-induced NLRP3 inflammasome activation and autophagy damage in macrophages by suppressing endoplasmic reticulum stress.

Lipotoxicity leads to numerous metabolic disorders such as nonalcoholic steatohepatitis. Luteolin, apigenin, and chrysin are three flavones with known antioxidant and anti-inflammatory properties, but whether they inhibit lipotoxicity-mediated NLRP3 inflammasome activation was unclear. To address this question, we used J774A.1 macrophages and Kupffer cells stimulated with 100 μM palmitate (PA) in the presence or absence of 20 μM of each flavone. PA increased p-PERK, p-IRE1α, p-JNK1/2, CHOP, and TXNIP as well as p62 and LC3-II expression and induced autophagic flux damage. Caspase-1 activation and IL-1β release were also noted after 24 h of exposure to PA. In the presence of the PERK inhibitor GSK2656157, PA-induced CHOP and TXNIP expression and caspase-1 activation were mitigated. Compared with PA treatment alone, Bcl-2 coupled to beclin-1 was elevated and autophagy was reversed by the JNK inhibitor SP600125. With luteolin, apigenin, and chrysin treatment, PA-induced ROS production, ER stress, TXNIP expression, autophagic flux damage, and apoptosis were ameliorated. Moreover, TXNIP binding to NLRP3 and IL-1β release in response to LPS/PA challenge were reduced. These results suggest that luteolin, apigenin, and chrysin protect hepatic macrophages against PA-induced NLRP3 inflammasome activation and autophagy damage by attenuating endoplasmic reticulum stress.

107 A Novel mutation in proteasomal gene PSMD7 results in activation of NLRP3 inflammasome and potentially predisposes to Necrotizing Fasciitis

107 A Novel mutation in proteasomal gene PSMD7 results in activation of NLRP3 inflammasome and potentially predisposes to Necrotizing Fasciitis

Not an immune cell, but they may act like one-cells with immune properties outside the immune system.

The cells presented in this work are not classified as cells that make up the immune system. They, however, present functions and molecules, which are characteristic of immune cells. These characteristic functions are, for example, sensing threat, performing phagocytosis, presentation of foreign antigens, cytokine release or enhancing immune memory. The enlisted immune response mechanisms are carried out by the possession of molecules such as Toll-like receptors, receptors for the Fc fragment of IgG, major histocompatibility complex class II molecules, costimulatory CD80/CD86 proteins and molecules needed for NLRP3 (NOD-like family pyrin domain containing 3) inflammasome activation. Thanks to these properties, the described nonimmune cells play an important role in the local immune response and support of the entire body in the fight against pathogens. They constitute the first line of defense of tissues and organs against pathogens and molecules recognized as harmful. The cells described in this article are particularly important in immunologically privileged places (e.g. the Bowman's capsule in the kidney), where "typical" immune cells normally do not have access. In this paper, we present immune-like functions and molecule suites of resident kidney cells (podocytes and mesangial cells), cochlear resident cells, fibrocytes and fibroblasts, as well as some stem cells (mesenchymal stem cells and umbilical cord Wharton's jelly-derived cells).

Potential Diagnostic Value of Abnormal Pyroptosis Genes Expression in Myelodysplastic Syndromes (MDS): A Primary Observational Cohort Study.

Background: Myelodysplastic syndromes (MDS) are determined by ineffective hematopoiesis and bone marrow cytological dysplasia with somatic gene mutations and chromosomal abnormalities. Accumulating evidence has revealed the pivotal role of NLRP3 inflammasome activation and pyroptotic cell death in the pathogenesis of MDS. Although MDS can be diagnosed with a variety of morphologic and cytogenetic tests, most of these tests have limitations or problems in practice. Materials and Methods: In the present study, we evaluated the expression of genes that form the inflammasome (NLRP3, ASC, and CASP1) in bone marrow specimens of MDS patients and compared the results with those of other leukemias to evaluate their diagnostic value for MDS. Primary samples of this observational cohort study were collected from aspiration samples of patients with myelodysplastic syndromes (27 cases) and patients with non-myelodysplastic syndrome hematological cancers (45 cases). After RNA extraction and c.DNA synthesis, candidate transcripts and housekeeping transcripts were measured by real-time PCR method (SYBER Green assay). Using Kruskal-Wallis the relative gene expressions were compared and differences with p value less than 0.05 were considered as significant. Discrimination capability, cut-off, and area under curve (AUC) of all markers were analyzed with recessive operation curve (ROC) analysis. Results: We found that Caspase-1 and ASC genes expressed at more levels in MDS specimens compared to non-MDS hematological malignancies. A relative average expression of 10.22 with a p-value of 0.001 and 1.86 with p=0.019 was detected for Caspase-1 and ASC, respectively. ROC curve analysis shows an AUC of 0.739 with p=0.0001 for Caspase-1 and an AUC of 0.665 with p=0.0139 for ASC to MDS discrimination. Conclusion: Our results show that Caspase-1 and ASC gene expression levels can be used as potential biomarkers for MDS diagnosis. Prospective studies with large sample numbers are suggested.

NLRP3 inflammasome activation triggers severe inflammatory liver injury in N, N-dimethylformamide-exposed mice

N,N-dimethylformamide (DMF) is a widely utilized chemical solvent with various industrial applications. Previous studies have indicated that the liver is the most susceptible target to DMF exposure, whereas the underlying mechanisms remain to be elucidated. This study aimed to investigate the role of NLRP3 inflammasome in DMF-induced liver injury in mice by using two NLRP3 inflammasome inhibitors, Nlrp3−/− mice, Nfe2l2−/− mice, and a macrophage-depleting agent. RNA sequencing revealed that endoplasmic reticulum (ER) stress and NLRP3 inflammasome-associated pathways were activated in the mouse liver after acute DMF exposure, which was validated by Western blotting. Interestingly, DMF-induced liver injury was effectively suppressed by two inflammasome inhibitors, MCC950 and Dapansutrile. In addition, knockout of Nlrp3 markedly attenuated DMF-induced liver injury without affecting the metabolism of DMF. Furthermore, silencing Nfe2l2 aggravated the liver injury and the NLRP3 inflammasome activation in mouse liver. Finally, the depletion of hepatic macrophages by clodronate liposomes significantly reduced the liver damage caused by DMF. These results suggest that NLRP3 inflammasome activation is the upstream molecular event in the development of acute liver injury induced by DMF.

Tranilast alleviates visceral hypersensitivity and colonic hyperpermeability by suppressing NLRP3 inflammasome activation in irritable bowel syndrome rat models

Visceral hypersensitivity resulting from compromised gut barrier with activated immune system is a key feature of irritable bowel syndrome (IBS). Corticotropin-releasing factor (CRF) and Toll-like receptor 4 (TLR4) activate proinflammatory cytokine signaling to induce these changes, which is one of the mechanisms of IBS. As activation of the NLRP3 inflammasome by lipopolysaccharide (LPS) or TLR4 leads to release interleukin (IL)-1β, the NLRP3 inflammasome may be involved in the pathophysiology of IBS. Tranilast, an anti-allergic drug has been demonstrated to inhibit the NLRP3 inflammasome, and we evaluated the impact of tranilast on visceral hypersensitivity and colonic hyperpermeability induced by LPS or CRF (IBS rat model). Visceral pain threshold caused by colonic balloon distention was measured by monitoring abdominal muscle contractions electrophysiologically. Colonic permeability was determined by quantifying the absorbed Evans blue within the colonic tissue. Colonic protein levels of NLRP3 and IL-1β were assessed by immunoblot or ELISA. Intragastric administration of tranilast (20–200 mg/kg) for 3 days inhibited LPS (1 mg/kg)-induced visceral hypersensitivity and colonic hyperpermeability in a dose-dependent manner. Simultaneously, tranilast also abolished these alterations induced by CRF (50 µg/kg). LPS increased colonic protein levels of NLRP3 and IL-1β, and tranilast inhibited these changes. β-hydroxy butyrate, an NLRP3 inhibitor, also abolished visceral hypersensitivity and colonic hyperpermeability caused by LPS. In contrast, IL-1β induced similar GI alterations to LPS, which were not modified by tranilast. In conclusion, tranilast improved visceral pain and colonic barrier by suppression of the NLRP3 inflammasome in IBS rat models. Tranilast may be useful for IBS treating.

TSPO deficiency exacerbates acute lung injury via NLRP3 inflammasome-mediated pyroptosis.

Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in many critically ill patients. Although inflammasome activation plays an important role in the induction of acute lung injury (ALI) and ARDS, the regulatory mechanism of this process is still unclear. When cells are stimulated by inflammation, the integrity and physiological function of mitochondria play a crucial part in pyroptosis. However, the underlying mechanisms and function of mitochondrial proteins in the process of pyroptosis are largely not yet known. Here, we identified the 18-kDa translocator protein (TSPO), a mitochondrial outer membrane protein, as an important mediator regulating nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in macrophages during ALI. TSPO gene knockout (KO) and lipopolysaccharide (LPS)-induced ALI/ARDS mouse models were employed to investigate the biological role of TSPO in the pathogenesis of ARDS. Murine macrophages were used to further characterize the effect of TSPO on the NLRP3 inflammasome pathway. Activation of NLRP3 inflammasome was preformed through LPS+adenosine triphosphate (ATP) co-stimulation, followed by detection of mitochondrial membrane potential, reactive oxygen species (ROS) production, and cell death to evaluate the potential biological function of TSPO. Comparisons between two groups were performed with a two-sided unpaired t -test. TSPO- KO mice exhibited more severe pulmonary inflammation in response to LPS-induced ALI. TSPO deficiency resulted in enhanced activation of the NLRP3 inflammasome pathway, promoting more proinflammatory cytokine production of macrophages in LPS-injured lung tissue, including interleukin (IL)-1β, IL-18, and macrophage inflammatory protein (MIP)-2. Mitochondria in TSPO -KO macrophages tended to depolarize in response to cellular stress. The increased production of mitochondrial damage-associated molecular pattern led to enhanced mitochondrial membrane depolarization and pyroptosis in TSPO -KO cells. TSPO may be the key regulator of cellular pyroptosis, and it plays a vital protective role in ARDS occurrence and development.

High Starch Induces Hematological Variations, Metabolic Changes, Oxidative Stress, Inflammatory Responses, and Histopathological Lesions in Largemouth Bass (Micropterus salmoides).

This study evaluated effects of high starch (20%) on hematological variations, glucose and lipid metabolism, antioxidant ability, inflammatory responses, and histopathological lesions in largemouth bass. Results showed hepatic crude lipid and triacylglycerol (TAG) contents were notably increased in fish fed high starch. High starch could increase counts of neutrophils, lymphocytes, monocytes, eosinophils, and basophils and serum contents of TAG, TBA, BUN, and LEP (p < 0.05). There were increasing trends in levels of GLUT2, glycolysis, gluconeogenesis, and LDH in fish fed high starch through the AKT/PI3K signal pathway. Meanwhile, high starch not only triggered TAG and cholesterol synthesis, but mediated cholesterol accumulation by reducing ABCG5, ABCG8, and NPC1L1. Significant increases in lipid droplets and vacuolization were also shown in hepatocytes of D3-D7 groups fed high starch. In addition, high starch could decrease levels of mitochondrial Trx2, TrxR2, and Prx3, while increasing ROS contents. Moreover, high starch could notably increase amounts of inflammatory factors (IL-1β, TNF-α, etc.) by activating NLRP3 inflammasome key molecules (GSDME, caspase 1, etc.). In conclusion, high starch could not only induce metabolic disorders via gluconeogenesis and accumulation of glycogen, TAG, and cholesterol, but could disturb redox homeostasis and cause inflammatory responses by activating the NLRP3 inflammasome in largemouth bass.

Podocyte-specific silencing of acid sphingomyelinase gene to abrogate hyperhomocysteinemia-induced NLRP3 inflammasome activation and glomerular inflammation.

Acid sphingomyelinase (ASM) has been reported to increase tissue ceramide and thereby mediate hyperhomocysteinemia (hHcy)-induced glomerular nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome activation, inflammation, and sclerosis. In the present study, we tested whether somatic podocyte-specific silencing of Smpd1 gene (mouse ASM gene code) attenuates hHcy-induced NLRP3 inflammasome activation and associated extracellular vesicle (EV) release in podocytes and thereby suppresses glomerular inflammatory response and injury. In vivo, somatic podocyte-specific Smpd1 gene silencing almost blocked hHcy-induced glomerular NLRP3 inflammasome activation in Podocre (podocyte-specific expression of cre recombinase) mice compared with control littermates. By nanoparticle tracking analysis (NTA), floxed Smpd1 shRNA transfection was found to abrogate hHcy-induced elevation of urinary EV excretion in Podocre mice. In addition, Smpd1 gene silencing in podocytes prevented hHcy-induced immune cell infiltration into glomeruli, proteinuria, and glomerular sclerosis in Podocre mice. Such protective effects of podocyte-specific Smpd1 gene silencing were mimicked by global knockout of Smpd1 gene in Smpd1-/- mice. On the contrary, podocyte-specific Smpd1 gene overexpression exaggerated hHcy-induced glomerular pathological changes in Smpd1trg/Podocre (podocyte-specific Smpd1 gene overexpression) mice, which were significantly attenuated by transfection of floxed Smpd1 shRNA. In cell studies, we also confirmed that Smpd1 gene knockout or silencing prevented homocysteine (Hcy)-induced elevation of EV release in the primary cultures of podocyte isolated from Smpd1-/- mice or podocytes of Podocre mice transfected with floxed Smpd1 shRNA compared with WT/WT podocytes. Smpd1 gene overexpression amplified Hcy-induced EV secretion from podocytes of Smpd1trg/Podocre mice, which was remarkably attenuated by transfection of floxed Smpd1 shRNA. Mechanistically, Hcy-induced elevation of EV release from podocytes was blocked by ASM inhibitor (amitriptyline, AMI), but not by NLRP3 inflammasome inhibitors (MCC950 and glycyrrhizin, GLY). Super-resolution microscopy also showed that ASM inhibitor, but not NLRP3 inflammasome inhibitors, prevented the inhibition of lysosome-multivesicular body interaction by Hcy in podocytes. Moreover, we found that podocyte-derived inflammatory EVs (released from podocytes treated with Hcy) induced podocyte injury, which was exaggerated by T cell coculture. Interstitial infusion of inflammatory EVs into renal cortex induced glomerular injury and immune cell infiltration. In conclusion, our findings suggest that ASM in podocytes plays a crucial role in the control of NLRP3 inflammasome activation and inflammatory EV release during hHcy and that the development of podocyte-specific ASM inhibition or Smpd1 gene silencing may be a novel therapeutic strategy for treatment of hHcy-induced glomerular disease with minimized side effect.NEW & NOTEWORTHY In the present study, we tested whether podocyte-specific silencing of Smpd1 gene attenuates hyperhomocysteinemia (hHcy)-induced nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome activation and associated inflammatory extracellular vesicle (EV) release in podocytes and thereby suppresses glomerular inflammatory response and injury. Our findings suggest that acid sphingomyelinase (ASM) in podocytes plays a crucial role in the control of NLRP3 inflammasome activation and inflammatory EV release during hHcy. Based on our findings, it is anticipated that the development of podocyte-specific ASM inhibition or Smpd1 gene silencing may be a novel therapeutic strategy for treatment of hHcy-induced glomerular disease with minimized side effects.

FoxG1 as a Potential Therapeutic Target for Alzheimer’s Disease: Modulating NLRP3 Inflammasome via AMPK/mTOR Autophagy Pathway

An increasing body of research suggests that promoting microglial autophagy hinders the neuroinflammation initiated though the NLRP3 inflammasome activation in Alzheimer’s disease (AD). The function of FoxG1, a crucial transcription factor involved in cell survival by regulating mitochondrial function, remains unknown during the AD process and neuroinflammation occurs. In the present study, we firstly found that Aβ peptides induced AD-like neuroinflammation upregulation and downregulated the level of autophagy. Following low-dose Aβ25–35 stimulation, FoxG1 expression and autophagy exhibited a gradual increase. Nevertheless, with high-concentration Aβ25–35 treatment, progressive decrease in FoxG1 expression and autophagy levels as the concentration of Aβ25–35 escalated. In addition, FoxG1 has a positive effect on cell viability and autophagy in the nervous system. In parallel with the Aβ25–35 stimulation, we employed siRNA to decrease the expression of FoxG1 in N2A cells. A substantial reduction in autophagy level (Beclin1, LC3II, SQSTM1/P62) and a notable growth in inflammatory response (NLRP3, TNF-α, and IL-6) were observed. In addition, we found FoxG1 overexpression owned the effect on the activation of AMPK/mTOR autophagy pathway and siRNA-FoxG1 successfully abolished this effect. Lastly, FoxG1 suppressed the NLRP3 inflammasome and enhanced the cognitive function in AD-like mouse model induced by Aβ25–35. Confirmed by cellular and animal experiments, FoxG1 suppressed NLRP3-mediated neuroinflammation, which was strongly linked to autophagy regulated by AMPK/mTOR. Taken together, FoxG1 may be a critical node in the pathologic progression of AD and has the potential to serve as therapeutic target.

Activation of the NLRP3 inflammasome by human adenovirus type 7 L4 100-kilodalton protein.

Human adenovirus type 7 (HAdV-7) is a significant viral pathogen that causes respiratory infections in children. Currently, there are no specific antiviral drugs or vaccines for children targeting HAdV-7, and the mechanisms of its pathogenesis remain unclear. The NLRP3 inflammasome-driven inflammatory cascade plays a crucial role in the host's antiviral immunity. Our previous study demonstrated that HAdV-7 infection activates the NLRP3 inflammasome. Building upon this finding, our current study has identified the L4 100 kDa protein encoded by HAdV-7 as the primary viral component responsible for NLRP3 inflammasome activation. By utilizing techniques such as co-immunoprecipitation, we have confirmed that the 100 kDa protein interacts with the NLRP3 protein and facilitates the assembly of the NLRP3 inflammasome by binding specifically to the NACHT and LRR domains of NLRP3. These insights offer a deeper understanding of HAdV-7 pathogenesis and contribute to the development of novel antiviral therapies.

Pterostilbene Protects against Osteoarthritis through NLRP3 Inflammasome Inactivation and Improves Gut Microbiota as Evidenced by In Vivo and In Vitro Studies.

Osteoarthritis (OA) is a persistent inflammatory disease, and long-term clinical treatment often leads to side effects. In this study, we evaluated pterostilbene (PT), a natural anti-inflammatory substance, for its protective effects and safety during prolonged use on OA. Results showed that PT alleviated the loss of chondrocytes and widened the narrow joint space in an octacalcium phosphate (OCP)-induced OA mouse model (n = 3). In vitro experiments demonstrate that PT reduced NLRP3 inflammation activation (relative protein expression: C: 1 ± 0.09, lipopolysaccharide (LPS): 1.14 ± 0.07, PT: 0.91 ± 0.07, LPS + PT: 0.68 ± 0.04) and the release of inflammatory cytokines through NF-κB signaling inactivation (relative protein expression: C: 1 ± 0.03, LPS: 3.49 ± 0.02, PT: 0.66 ± 0.08, LPS + PT: 2.78 ± 0.05), ultimately preventing cartilage catabolism. Interestingly, PT also altered gut microbiota by reducing inflammation-associated flora and increasing the abundance of healthy bacteria in OA groups. Collectively, these results suggest that the PT can be considered as a protective strategy for OA.

HP-MSCs attenuate severe acute pancreatitis in mice via inhibiting NLRP3 inflammasome-mediated acinar cell pyroptosis.

Severe acute pancreatitis (SAP) is a serious gastrointestinal disease that is facilitated by pancreatic acinar cell death. The protective role of human placental mesenchymal stem cells (hP-MSCs) in SAP has been demonstrated in our previous studies. However, the underlying mechanisms of this therapy remain unclear. Herein, we investigated the regularity of acinar cell pyroptosis during SAP and investigated whether the protective effect of hP-MSCs was associated with the inhibition of acinar cell pyroptosis. A mouse model of SAP was established by the retrograde injection of sodium taurocholate (NaTC) solution in the pancreatic duct. For the hP-MSCs group, hP-MSCs were injected via the tail vein and were monitored in vivo. Transmission electron microscopy (TEM) was used to observe the pyroptosis-associated ultramorphology of acinar cells. Immunofluorescence and Western blotting were subsequently used to assess the localization and expression of pyroptosis-associated proteins in acinar cells. Systemic inflammation and local injury-associated parameters were evaluated. Acinar cell pyroptosis was observed during SAP, and the expression of pyroptosis-associated proteins initially increased, peaked at 24h, and subsequently showed a decreasing trend. hP-MSCs effectively attenuated systemic inflammation and local injury in the SAP model mice. Importantly, hP-MSCs decreased the expression of pyroptosis-associated proteins and the activity of the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in acinar cells. Our study demonstrates the regularity and important role of acinar cell pyroptosis during SAP. hP-MSCs attenuate inflammation and inhibit acinar cell pyroptosis via suppressing NLRP3 inflammasome activation, thereby exerting a protective effect against SAP.