BRD3308 suppresses macrophage oxidative stress and pyroptosis via upregulating acetylation of H3K27 in sepsis-induced acute lung injury.

Background: Sepsis-induced acute lung injury (ALI) leads to severe hypoxemia and respiratory failure, contributing to poor prognosis in septic patients. Endotoxin dissemination triggers oxidative stress and the release of inflammatory cytokines in macrophages, initiating diffuse alveolar damage. The role of epigenetic histone modifications in organ injury is increasingly recognized. The present study aimed to investigate the use of a histone modification inhibitor to alleviate sepsis-induced ALI, revealing a new strategy for improving sepsis patient survival. Methods: In vivo models of ALI were established through the intraperitoneal injection of lipopolysaccharide and cecal ligation and puncture surgery. Furthermore, the disease process was simulated in vitro by stimulating Tamm-Horsfall protein-1 (THP-1) cells with lipopolysaccharide. Hematoxylin and eosin staining, blood gas analysis and pulmonary function tests were utilized to assess the extent of lung tissue damage. Western blot analysis, real-time polymerase chain reaction, enzyme-linked immunosorbent assay and immunofluorescence were used to measure the levels and distribution of the indicated indicators within cells and tissues. Reactive oxygen species and autophagic flux alterations were detected using specific probes. Results: BRD3308, which is a inhibitor of histone deacetylase 3, improved lung tissue damage, inflammatory infiltration and edema in ALI by inhibiting Nod-like receptor protein3-mediated pyroptosis in macrophages. By upregulating autophagy, BRD3308 improved the disruption of redox balance in macrophages and reduced the accumulation of reactive oxygen species. Mechanistically, BRD3308 inhibited histone deacetylase 3 activity by binding to it and altering its conformation. Following histone deacetylase 3 inhibition, acetylation of H3K27 was significantly increased. Moreover, the increase in H3K27Ac led to the upregulation of autophagy-related gene 5, a key component of autophagosomes, thereby activating autophagy. Conclusions: BRD3308 inhibits oxidative stress and pyroptosis in macrophages by modulating histone acetylation, thereby preventing sepsis-induced ALI. The present study provides a potential strategy and theoretical basis for the clinical treatment of sepsis-induced ALI.

Mammary hydroxylated oestrogen activates the NLRP3 inflammasome in tumor-associated macrophages to promote breast cancer progression and metastasis.

Breast cancer remains one of the primary causes of cancer-related death. An imbalance of oestrogen homeostasis and an inflammatory tumor microenvironment (TME) are vital risk factors for the progression and metastasis of breast cancer. Here, we showed that oestrogen homeostasis was disrupted both in breast cancer patients and in a transgenic MMTV-PyMT mouse model of breast cancer, and significant levels of hydroxylated oestrogen accumulated in the mammary tissues of these patients and mice. We also observed that tumor-associated macrophages (TAMs) were the main population of immune cells present in the breast TME. TAM-dependent tumor metastasis could be triggered by hydroxylated oestrogen via NLRP3 inflammasome activation and IL-1ß production. Mechanistically, TAM-derived inflammatory cytokines induced the expression of matrix metalloproteinases (MMPs) in breast tumor cells, leading to breast tumor invasion and metastasis. Conceptually, our study reveals a previously unknown role of hydroxylated oestrogen in the reprogramming of the TME via NLRP3 inflammasome activation in TAMs, which ultimately facilitates breast cancer cells proliferation, migration, and invasion.

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

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/ß-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/ß-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.

Five Undescribed Sesquiterpenes with Anti-inflammasome Activity Isolated from Saussurea laniceps.

Five previously undescribed guaialactone-type sesquiterpenes (1-5), called Lanicepsmines A-E, along with eleven know compounds (6-16), were isolated from the whole plant of Saussurea laniceps. NMR spectroscopic data analysis and MASS permitted the definition of their structures. The stereochemistry of the compounds was confirmed by ECD calculations. It is worth noting that compound 1 and 2 contain amino groups. Part of compounds were tested the anti-inflammasome activity, and compound 14 exhibited potent activity and decreased LDH level in a dose-dependent manner, with IC50 values of 0.698 µM.

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

PURPOSE: Radioresistance 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 MATERIALS: RNA 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 ß-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. RESULTS: RSPO3 expression was downregulated in radioresistant NSCLC cells. Overexpression of RSPO3 increased NSCLC radiosensitivity through the induction of pyroptosis, which was mediated by the ß-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. CONCLUSIONS: The 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.

Role of ASC, a key component of the inflammasome in the antimicrobial process in black rockfish (Sebastes schlegelii).

Apoptosis-associated speck-like protein containing a CARD (ASC) serves as a pivotal component within the inflammasome complex, playing a critical role in the activation of the innate immune response against pathogenic infection. However, the functional significance of inflammasome ASC in teleosts remains unclear. In this study, the coding sequence (CDS) region of ASC gene of Sebastes schlegelii (SsASC) was cloned, and we observed a high conservation of SsASC with teleosts through comprehensive bioinformatics analysis. SsASC and SsCaspase-1 were found to be highly expressed in immune tissues such as spleen and head kidney. Furthermore, our findings revealed that SsASC interacts with SsCaspase-1 through CARD-CARD interactions to generate oligomeric speck-like structures, whereas the PYD structural domain of SsASC forms only filamentous structures. To further understand the role of SsASC in combating Edwardsiella piscicida (E. piscicida) infection, we developed a SsASC knockdown model using in vivo siRNA injection and E. piscicida challenge via intraperitoneal injection. The model demonstrated that E. piscicida infection up-regulated SsASC expression, which was markedly reduced upon SsASC knockdown. Concurrently, E. piscicida colonization was significantly enhanced in the knockdown group, accompanied by a suppression of inflammatory factor expression. These findings confirm the pivotal antibacterial and anti-infective role of SsASC in the Sebastes schlegelii immune response upon E. piscicida stimulation. Our study highlights the significance of SsASC in the innate immune defense mechanism of teleosts against bacterial pathogens.

Shikonin mitigates cyclophosphamide-induced cardiotoxicity in mice: the role of sirtuin-1, NLRP3 inflammasome, autophagy, and apoptosis.

OBJECTIVES: The aim of this study was to elucidate the protective potential of shikonin (SHK) on cyclophosphamide (CP)-induced cardiotoxicity in Swiss albino mice. METHODS: Mice received SHK in three different doses by oral gavage daily for 14 days and CP at 100 mg/kg, intraperitoneally once on the seventh day. On the 15th day, mice were euthanized, blood collected, and hearts were removed to estimate various biochemical and histopathological parameters. KEY FINDINGS: CP significantly increased serum lactate dehydrogenase, creatine kinase-MB, troponin I and NT pro-BNP, and cardiac malondialdehyde and decreased cardiac total antioxidant capacity and Nrf2, whereas increased inflammatory markers in the cardiac tissues. CP also caused hypertrophy and fibrosis in the cardiac tissues via activation of IL6/JAK2/STAT3 while depressed SIRT1 and PI3K/p-Akt pathway with consequent increased apoptosis and dysregulation of autophagy. SHK treatment reversed these changes in a dose-dependent manner and showed a significant protective effect against CP-induced cardiotoxicity via suppressing oxidative stress, inflammation, and apoptosis with modulation of autophagy via induction of SIRT1/PI3K/p-Akt signaling. CONCLUSIONS: Shikonin may be used as an adjuvant to cyclophosphamide in cancer treatment, but further research is needed to investigate its effects on cardiotoxicity in distinct animal cancer models.

Echinacoside Alleviates Carbon Tetrachloride-Induced Chronic Liver Injury by Modulating the NF-κB/NLRP3 Inflammasome Pathway.

The purpose of this study was to investigate the protective effect of echinacoside (Ech) on carbon tetrachloride (CCL4)-induced chronic liver injury in rats and its potential mechanisms. Thirty Sprague-Dawley (SD) rats were randomly divided into five groups: the Control group, the CCL4 group, the CCL4 + Ech 25 mg/kg group, the CCL4 + Ech 50 mg/kg group, and the CCL4 + Ech 100 mg/kg group. The rats were injected intraperitoneally with CCL4 solution twice a week to induce chronic liver injury, and Ech intervention lasted for 4 weeks. After the intervention, the liver and blood samples from rats were collected for subsequent analysis. Ech effectively reduced the levels of serum liver injury markers (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, alkaline phosphatase, and total bilirubin), attenuated the hepatocyte degeneration and necrosis, improved the severity of liver fibrosis, and inhibited the local inflammatory response of the liver in a dose-dependent manner. Ech effectively mitigated CCL4-induced chronic liver injury in rats by downregulating the NF-κB/NLRP3 inflammasome pathway.

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.

Formulating a TMEM176B blocker in chitosan nanoparticles uncouples its paradoxical roles in innate and adaptive antitumoral immunity.

The immunoregulatory cation channel TMEM176B plays a dual role in tumor immunity. On the one hand, TMEM176B promotes antigen cross-presentation to CD8+ T cells by regulating phagosomal pH in dendritic cells (DCs). On the other hand, it inhibits NLRP3 inflammasome activation through ionic mechanisms in DCs, monocytes and macrophages. We speculated that formulating BayK8644 in PEGylated chitosan nanoparticles (NP-PEG-BayK8644) should slowly release the compound and by that mean avoid cross-presentation inhibition (which happens with a fast 30 min kinetics) while still triggering inflammasome activation. Chitosan nanocarriers were successfully obtained, exhibiting a particle size within the range of 200 nm; they had a high positive surface charge and a 99 % encapsulation efficiency. In in vitro studies, NP-PEG-BayK8644 did not inhibit antigen cross-presentation by DCs, unlike the free compound. The NP-PEG-BayK8644 activated the inflammasome in a Tmem176b-dependent manner in DCs. We administered either empty (eNP-PEG) or NP-PEG-BayK8644 to mice with established tumors. NP-PEG-BayK8644 significantly controlled tumor growth and improved mice survival compared to both eNP-PEG and free BayK8644 in melanoma and lymphoma models. This effect was associated with enhanced inflammasome activation by DCs in the tumor-draining lymph node and infiltration of the tumor by CD8+ T cells. Thus, encapsulation of BayK8644 in chitosan NPs improves the anti-tumoral properties of the compound by avoiding inhibition of antigen cross-presentation.

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

BACKGROUND AND PURPOSE: 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. EXPERIMENTAL APPROACH: 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. KEY RESULTS: 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-ß-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. CONCLUSION AND IMPLICATIONS: 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.

Clinical Utility of Rilonacept for the Treatment of Recurrent Pericarditis: Design, Development, and Place in Therapy.

Recurrent pericarditis (RP) has been traditionally regarded as a "nightmare" for both clinicians and patients. Until approximately a decade ago, available treatments were thin on the ground with non-steroidal anti-inflammatory medications, glucocorticoids, colchicine, and classical immunosuppressants being the only options. The first important step in the tale of RP was the advent of colchicine in clinical practice, which has been shown to halve the rate of first and subsequent pericarditis recurrences. The second major breakthrough advance in this setting was the introduction of interleukin-1 inhibitors based on the recently unveiled autoinflammatory nature of pericarditis. At present, anti-interleukin-1 inhibitors available for clinical use in patients with refractory RP include anakinra and rilonacept, with the latter having obtained FDA approval for this indication. Apart from the remarkable efficacy and good safety profile which is a common feature of all anti-interleukin-1 compounds, rilonacept has the advantage of weekly administration (instead of daily compared to anakinra) which is important in terms of adherence to treatment and improved quality of life albeit at the expense of a higher cost. This review aims to summarize the available evidence on the role of rilonacept in the treatment of RP and the reduction of the recurrences risk.

Combined bacterial translocation and cholestasis aggravates liver injury by activation pyroptosis in obstructive jaundice.

This study explores the mechanism by which obstructive jaundice (OJ) induces liver damage through pyroptosis. We induced OJ in rats via bile duct ligation and assessed liver damage using serum biochemical markers and histological analysis of liver tissue. Pyroptosis was investigated through immunofluorescence, ELISA, Western blot, and quantitative RT-PCR techniques. Additionally, we examined intestinal function and fecal microbiota alterations in the rats using 16S rDNA sequencing. In vitro experiments involved co-culturing Kupffer cells and hepatocytes, which were then exposed to bile and lipopolysaccharide (LPS). Our findings indicated that OJ modified the gut microbiota, increasing LPS levels, which, in conjunction with bile, initiated a cycle of inflammation, fibrosis, and cell death in the liver. Mechanistically, OJ elevated necrotic markers such as ATP, which in turn activated pyroptotic pathways. Increased levels of pyroptosis-related molecules, including NLRP3, caspase-1, gasdermin D, and IL-18, were confirmed. In our co-cultured cell model, bile exposure resulted in cell death and ATP release, leading to the activation of the NLRP3 inflammasome and its downstream effectors, caspase-1 and IL-18. The combination of bile and LPS significantly intensified pyroptotic responses. This study is the first to demonstrate that LPS and bile synergistically exacerbate liver injury by promoting necrosis and pyroptosis, unveiling a novel mechanism of OJ-associated hepatic damage and suggesting avenues for potential preventive or therapeutic interventions.

Bystander monocytic cells drive infection-independent NLRP3 inflammasome response to SARS-CoV-2.

The pathogenesis of COVID-19 is associated with a hyperinflammatory immune response. Monocytes and macrophages play a central role in this hyperinflammatory response to SARS-CoV-2. NLRP3 inflammasome activation has been observed in monocytes of patients with COVID-19, but the mechanism and consequences of inflammasome activation require further investigation. In this study, we inoculated a macrophage-like THP-1 cell line, primary differentiated human nasal epithelial cell (hNEC) cultures, and primary monocytes with SARS-CoV-2. We found that the activation of the NLRP3 inflammasome in macrophages does not rely on viral replication, receptor-mediated entry, or actin-dependent entry. SARS-CoV-2 productively infected hNEC cultures without triggering the production of inflammasome cytokines IL-18 and IL-1ß. Importantly, these cytokines did not inhibit viral replication in hNEC cultures. SARS-CoV-2 inoculation of primary monocytes led to inflammasome activation and induced a macrophage phenotype in these cells. Monocytic cells from bronchoalveolar lavage (BAL) fluid, but not from peripheral blood, of patients with COVID-19, showed evidence of inflammasome activation, expressed the proinflammatory marker CD11b, and displayed oxidative burst. These findings highlight the central role of activated macrophages, as a result of direct viral sensing, in COVID-19 and support the inhibition of IL-1ß and IL-18 as potential therapeutic strategies to reduce immunopathology without increasing viral replication. IMPORTANCE: Inflammasome activation is associated with severe COVID-19. The impact of inflammasome activation on viral replication and mechanistic details of this activation are not clarified. This study advances our understanding of the role of inflammasome activation in macrophages by identifying TLR2, NLRP3, ASC, and caspase-1 as dependent factors in this activation. Further, it highlights that SARS-CoV-2 inflammasome activation is not a feature of nasal epithelial cells but rather activation of bystander macrophages in the airway. Finally, we demonstrate that two pro inflammatory cytokines produced by inflammasome activation, IL-18 and IL-1ß, do not restrict viral replication and are potential targets to ameliorate pathological inflammation in severe COVID-19.

C9orf72 dipeptides activate the NLRP3 inflammasome.

Frontotemporal dementia and amyotrophic lateral sclerosis are neurodegenerative diseases with considerable clinical, genetic and pathological overlap. The most common cause of both diseases is a hexanucleotide repeat expansion in C9orf72. The expansion is translated to produce five toxic dipeptides, which aggregate in patient brain. Neuroinflammation is a feature of frontotemporal dementia and amyotrophic lateral sclerosis; however, its causes are unknown. The nod-like receptor family, pyrin domain-containing 3 inflammasome is implicated in several other neurodegenerative diseases as a driver of damaging inflammation. The inflammasome is a multi-protein complex which forms in immune cells in response to tissue damage, pathogens or aggregating proteins. Inflammasome activation is observed in models of other neurodegenerative diseases such as Alzheimer's disease, and inflammasome inhibition rescues cognitive decline in rodent models of Alzheimer's disease. Here, we show that a dipeptide arising from the C9orf72 expansion, poly-glycine-arginine, activated the inflammasome in microglia and macrophages, leading to secretion of the pro-inflammatory cytokine, interleukin-1ß. Poly-glycine-arginine also activated the inflammasome in organotypic hippocampal slice cultures, and immunofluorescence imaging demonstrated formation of inflammasome specks in response to poly-glycine-arginine. Several clinically available anti-inflammatory drugs rescued poly-glycine-arginine-induced inflammasome activation. These data suggest that C9orf72 dipeptides contribute to the neuroinflammation observed in patients, and highlight the inflammasome as a potential therapeutic target for frontotemporal dementia and amyotrophic lateral sclerosis.

Hua-Shi-Bai-Du decoction inactivates NLRP3 inflammasome through inhibiting PDE4B in macrophages and ameliorates mouse acute lung injury.

BACKGROUND: Hua-Shi-Bai-Du decoction (HSBD) exerts significant effects on the prevention and treatment of COVID-19 in China. The activation of the NLRP3 inflammasome of macrophages plays a vital role in COVID-19 pathology. However, no previous studies have focused on this pathological process to explore the effect of HSBD. PURPOSE: Our aim is to uncover the effect of HSBD on NLRP3 inflammasome activation and the underlying mechanisms. METHODS: The NLRP3-activated J774A.1 cells primed by LPS and activated by nigericin/ATP/MSU were used to evaluate NLRP3 activation in vitro. ASC oligomerization and speck formation were assessed by western blot and immunofluorescence imaging. Intracellular K+ levels were determined by the colorimetric assay. Mitochondrial ROS (mtROS) level was detected by the flow cytometry and the fluorescence spectrophotometry. The intracellular cAMP level was determined by chemiluminescence method and ELISA, while phosphodiesterase (PDE) activity was measured using the fluorescent substrate MANT-cAMP. siRNA was applied to knockdown PDE4B. Two in vivo mouse models, MSU-induced peritonitis and LPS-induced acute lung injury (ALI), were used to evaluate the effects of HSBD on IL-1ß and other inflammatory cytokines. Pathological changes in lung tissue were observed by histopathological examination. RESULTS: HSBD not only decreased supernatant IL-1ß, caspase-1 p20, and cleaved gasdermin D (GSDMD) in NLRP3-activated J774A.1 cells, but also reduced IL-1ß in the peritoneal lavage fluid of mice with MSU-induced peritonitis, demonstrating the suppressive effect on NLRP3 inflammasome activation. The mechanism study showed that HSBD blocked ASC oligomerization and speck formation without affecting K+ efflux or mtROS production. Furthermore, it prevented the decrease of intracellular cAMP by inhibiting PDE4B activity. And in the PDE4B-deficient cells, its suppressive effect on IL-1ß release was abolished. In LPS-induced ALI mice, oral administration of HSBD decreased several proinflammatory cytokines (IL-1ß, IL-6, TNF-α, and CXCL-1) and attenuated the pathological damage to the lung. CONCLUSION: HSBD suppresses the activation of NLRP3 inflammasome by inhibiting PDE4B activity to counteract the decrease of intracellular cAMP, thereby blocking ASC oligomerization in macrophages. Our findings may provide new insight into the clinical effets of HSBD for the treatment of COVID-19.

Dihydromyricetin suppresses endothelial NLRP3 inflammasome activation and attenuates atherogenesis by promoting mitophagy.

BACKGROUND: NOD-like receptor protein 3 (NLRP3) inflammasome activation is indispensable for atherogenesis. Mitophagy has emerged as a potential strategy to counteract NLRP3 inflammasome activation triggered by impaired mitochondria. Our previous research has indicated that dihydromyricetin, a natural flavonoid, can mitigate NLRP3-mediated endothelial inflammation, suggesting its potential to treat atherosclerosis. However, the precise underlying mechanisms remain elusive. This study sought to investigate whether dihydromyricetin modulates endothelial mitophagy and inhibits NLRP3 inflammasome activation to alleviate atherogenesis, along with the specific mechanisms involved. METHODS: Apolipoprotein E-deficient mice on a high-fat diet were administered daily oral gavages of dihydromyricetin for 14 weeks. Blood samples were procured to determine the serum lipid profiles and quantify proinflammatory cytokine concentrations. Aortas were harvested to evaluate atherosclerotic plaque formation and NLRP3 inflammasome activation. Concurrently, in human umbilical vein endothelial cells, Western blotting, flow cytometry, and quantitative real-time PCR were employed to elucidate the mechanistic role of mitophagy in the modulation of NLRP3 inflammasome activation by dihydromyricetin. RESULTS: Dihydromyricetin administration significantly attenuated NLRP3 inflammasome activation and vascular inflammation in mice on a high-fat diet, thereby exerting a pronounced inhibitory effect on atherogenesis. Both in vivo and in vitro, dihydromyricetin treatment markedly enhanced mitophagy. This enhancement in mitophagy ameliorated the mitochondrial damage instigated by saturated fatty acids, thereby inhibiting the activation and nuclear translocation of NF-κB. Consequently, concomitant reductions in the transcript levels of NLRP3 and interleukin-1ß (IL-1ß), alongside decreased activation of NLRP3 inflammasome and IL-1ß secretion, were discerned. Notably, the inhibitory effects of dihydromyricetin on the activation of NF-κB and subsequently the NLRP3 inflammasome were determined to be, at least in part, contingent upon its capacity to promote mitophagy. CONCLUSION: This study suggested that dihydromyricetin may function as a modulator to promote mitophagy, which in turn mitigates NF-κB activity and subsequent NLRP3 inflammasome activation, thereby conferring protection against atherosclerosis.

Deficiency of 5-HT2B receptors alleviates atherosclerosis by regulating macrophage phenotype through inhibiting interferon signalling.

BACKGROUND AND PURPOSE: Elevated levels of 5-HT have been correlated with coronary artery disease and cardiac events, suggesting 5-HT is a potential novel factor in the development of atherosclerotic cardiovascular disease. However, the underlying pathological mechanisms of the 5-HT system in atherosclerosis remain unclear. The 5-HT2B receptor (5-HT2BR), which establishes a positive feedback loop with 5-HT, has been identified as a contributor to pathophysiological processes in various vascular disorders. In this study, we investigated the immunological impact of 5-HT2BR in atherosclerosis-prone apolipoprotein E-deficient (ApoE-/-) mice. EXPERIMENTAL APPROACH: Plasma levels of 5-HT were measured in mice using an ELISA kit. Atherosclerotic plaque formation, macrophage infiltration and inflammatory signalling were assessed in ApoE-/- mice by employing both pharmacological inhibition and genetic deficiency of 5-HT2BR. Inflammasome activation was elucidated using peritoneal macrophages isolated from 5-HT2BR-deficient mice. KEY RESULTS: An upregulation of 5-HT2BR expression was observed in the aortas of ApoE-/- mice, exhibiting a strong correlation with the presence of macrophages in plaques. Atherosclerosis was attenuated in mice through pharmacological inhibition and genetic deficiency of 5-HT2BR. Additionally, a significant reduction in atherosclerotic plaque size was achieved through bone marrow reconstitution with 5-HT2BR-deficient cells. 5-HT2BR-deficient macrophages showed attenuated interferon (IFN) signalling, NLRP3 inflammasome activation, and interleukin-1ß release. Moreover, macrophages primed with 5-HT2BR deficiency displayed an anti-inflammatory phenotype. CONCLUSION AND IMPLICATIONS: These findings support the hypothesis that 5-HT2BR in macrophages plays a causal role in the development of atherosclerosis, revealing a novel perspective for potential therapeutic strategies in atherosclerosis-related diseases.

Exploring the correlation between innate immune activation of inflammasome and regulation of pyroptosis after intracerebral hemorrhage: From mechanism to treatment.

Stroke has emerged as the primary cause of disability and death globally in recent years. Intracerebral hemorrhage (ICH), a particularly severe kind of stroke, is occurring in an increasing number of people. The two main clinical treatments for ICH now in use are conservative pharmaceutical therapy and surgical intervention, both of which have risks and drawbacks. Consequently, it is crucial to look into the pathophysiology of ICH and consider cutting-edge therapeutic approaches. Recent research has revealed that pyroptosis is a newly identified type of cell death distinguished by the break of the cell membrane and the discharge of pro-inflammatory substances through different routes. Following ICH, glial cells experience pyroptosis, which worsens neuroinflammation. Hence, the onset and progression of ICH are strongly linked to pyroptosis, which is facilitated by different inflammasomes. It is essential to conduct a comprehensive investigation of ICH damage processes and uncover new targets for treatment. The impact and function of pyroptosis in ICH, as well as the activation and regulation of inflammasomes and their mediated pyroptosis pathways will be fully discussed in this review.