Ameliorative effect of selective NLRP3 inflammasome inhibitor MCC950 in an ovalbumin-induced allergic rhinitis murine model.

Allergic rhinitis (AR) is a complex IgE-mediated nasal allergic and inflammatory disease. Nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) is essential in the process of allergic and inflammatory responses. MCC950 is a selective NLRP3 inhibitor. However, its role and mechanism in AR remains undetermined. The present study aimed to explore the effect and mechanism of MCC950 on an ovalbumin (OVA) induced mouse model of AR. The AR BALB/c mice were constructed using OVA and administrated intranasally with MCC950. Concentrations of OVA-specific IgE, histamines and leukotrienes C4 (LTC4) in serum, and OVA-specific IgE, ECP, IFN-γ, IL-4, IL-5, IL-13, IL-1β and IL-18 in nasal lavage fluid (NLF) were assayed by enzyme-linked immunosorbent assay (ELISA). Inflammatory cells were counted in NLF. HE and PAS staing were used for evaluating eosinophils and goblet cells. Immunohistochemistry (IHC) staining were employed to evaluate immunolabeling of NLRP3, Caspase-1, ASC, IL-1β and IL-18 in nasal mucosas of mice. Real-time PCR was conducted to assay NLRP3, Caspase-1, ASC, IL-1β and IL-18 mRNA levels. In vitro studies, western blotting, real-time PCR and ELISA were performed to evaluate the effects and mechanisms of OVA and NLRP3 inhibitor MCC950 on spleen mononuclear cells. We found significant downregulation of sneezing, nasal rubbing, inflammatory cytokines, inflammatory cells and NLRP3, Caspase-1, ASC, IL-1β and IL-18 expression in MCC950 treated mice compared with untreated AR mice. In spleen mononuclear cells culture and stimulation experiment, NLRP3, Caspase-1, ASC, IL-1β and IL-18 levels were upregulated by OVA but inhibited by MCC950. In conclusion, MCC950 could effectively exert its ameliorative effect in murine AR by inhibiting NLRP3 and leads to reduction of Caspase-1, ASC, IL-1β and IL-18, resulting in the attenuation of the allergic and inflammatory responses.

Zhang W ，Ba G ，Tang R ，Li M ，Lin H ... -  《-》

The selective NLRP3-inflammasome inhibitor MCC950 reduces myocardial fibrosis and improves cardiac remodeling in a mouse model of myocardial infarction.

Early inflammatory responses after myocardial infarction (MI) are likely to increase myocardial fibrosis and subsequent cardiac remodeling. MCC950, a specific NLRP3 inhibitor, was previously found to effectively inhibit the release of inflammatory factors IL-18 and IL-1β. In this study, we evaluated the effect of MCC950, as a potential new treatment strategy for MI, on myocardial fibrosis and cardiac remodeling using an experimental mouse model. Male C57BL/6 mice were subjected to left coronary artery ligation to induce MI and then treated with MCC950 (10 mg/kg) or PBS for 14 days. After 30 days, echocardiography was performed to assess cardiac function and myocardial fibrosis was evaluated using H&E- and Masson's Trichrome-stained sections. Myocardial expression of inflammatory factors and fibrosis markers was analyzed by western blotting, immunofluorescence, ELISA, and real-time quantitative PCR. The ejection fraction in the 10 mg/kg group (40.7 ± 4.2%; N = 6, p = 0.0029) was statistically preserved compared to that in the control group (14.0 ± 4.4%). Myocardial fibrosis was also reduced in MCC950-treated animals (MCC950, 23.2 ± 3.0 vs PBS, 36.2 ± 3.7; p < 0.05). Moreover, myocardial NLRP3, cleaved IL-1β, and IL-18 levels were reduced in MCC950-treated animals. H&E and molecular examination revealed decreases in inflammatory cell infiltration and inflammatory factor expression in the heart. In vitro, MCC950 inhibited NLRP3, reduced caspase-1 activity, and further downregulated IL-1β and IL-18. MCC950, as a specific NLRP3 inhibitor, can alleviate fibrosis and improve cardiac function in a mouse model by suppressing early inflammatory responses post-MI.

Gao R ，Shi H ，Chang S ，Gao Y ，Li X ，Lv C ，Yang H ，Xiang H ，Yang J ，Xu L ，Tang Y ... -  《-》

MicroRNA-133b Ameliorates Allergic Inflammation and Symptom in Murine Model of Allergic Rhinitis by Targeting Nlrp3.

Emerging evidences indicate that post-transcriptional regulation by microRNAs is critical in allergic rhinitis (AR) pathogenesis. MircroRNA-133b (miR-133b) was recently suggested as a potential predictor of AR. However, the in vivo effect of miR-133b on AR is unclear. AR model was established in BALB/c mice by intraperitoneal sensitization and intranasal challenge with ovalbumin (OVA). MiR-133b agomir was then intranasally administrated to mice after OVA challenge for another 7 days. The symptom of nasal rubbing and sneezing were recorded after the last OVA challenge. Nasal mucosa tissues and serum were collected. MiR-133b expression, serum OVA-specific immunoglobulin E (IgE) concentration, proinflammatory cytokines (TNF-α, IL-4, IL-5, IL-10 and IFN-γ) levels, and Nlrp3 inflammasome activation were measured by RT-PCR, ELISA, western blotting or immunohistochemistry, respectively. Histopathologic changes were evaluated using hematoxylin and eosin and Sirius red staining. The luciferase activity and protein expression of Nlrp3 were also determined. MiR-133b expression was significantly decreased in nasal mucosa of AR mice, which was restored by nasal administration with miR-133b agomir. Upregulation of miR-133b markedly reduced the concentration of OVA-specific IgE, the frequencies of nasal rubbing and sneezing, and the levels of cytokines (TNF-α, IL-4, IL-5 and IFN-γ). Levels of IL-4, IL-5, IL-10 and IFN-γ produced by cervical lymph node cells were significantly lowered in miR-133b agomir-treated mice. Moreover, miR-133b also appeared to strongly attenuate pathological alterations and eosinophils and mast cells infiltration in nasal mucosa. Notably, we demonstrated for the first time that miR-133b negatively regulated Nlrp3 expression through binding with the 3' untranslated region of Nlrp3. Consequently, infection of miR-133b in nasal mucosa remarkably suppressed the Nlrp3 inflammasome activation, as evidenced by reduced Nlrp3, Caspase-1, ASC, IL-18 and IL-1 expressions. MiR-133b alleviates allergic symptom in AR mice by inhibition of Nlrp3 inflammasome-meditated inflammation. These findings provide us an insight into the potential role of miR-133b in relation to AR treatment.

Xiao L ，Jiang L ，Hu Q ，Li Y ... -  《-》

Immunomodulation in allergic rhinitis: Insights from Th2 cells and NLRP3/IL-18 pathway.

Allergic rhinitis (AR) is characterized by nasal symptoms such as rubbing and sneezing, often triggered by allergen exposure. The purpose of this study is to dissect the roles of NLRP3-mediated immune modulation and macrophage pyroptosis in modulating T cell differentiation within the context of ovalbumin (OVA)-induced AR in mice. OVA-induced AR was established in mice, evaluating nasal symptoms, macrophage infiltration, cytokine levels, and T cell differentiation. Manipulations using NLRP3-/-, ASC-/- mice, clodronate liposome treatment, and NLRP3 inhibitor MCC950 were performed to assess their impact on AR symptoms and immune responses. Following OVA stimulation, increased nasal symptoms were observed in the OVA group along with augmented GATA3 expression and elevated IL-4 and IL-1b levels, indicative of Th2 polarization and cellular pyroptosis involvement. NLRP3-/- and ASC-/- mice exhibited reduced CD3+ T cells post OVA induction, implicating cellular pyroptosis in AR. Macrophage depletion led to decreased IgE levels, highlighting their involvement in allergic responses. Further investigations revealed enhanced macrophage pyroptosis, influencing Th1/Th2 differentiation in AR models. IL-18 released through NLRP3-mediated pyroptosis induced Th2 differentiation, distinct from IL-1b. Additionally, MCC950 effectively mitigated AR symptoms by modulating Th2 responses and reducing macrophage infiltration. This comprehensive study unravels the pivotal role of NLRP3-mediated immune modulation and macrophage pyroptosis in Th1/Th2 balance regulation in OVA-induced AR. Targeting NLRP3 pathways with MCC950 emerged as a promising strategy to alleviate AR symptoms, providing insights for potential therapeutic interventions in AR management.

Hu X ，Liu S ，Jing Z ，He Y ，Qin G ，Jiang L ... -  《-》

NLRP3 inflammasome blockade reduces liver inflammation and fibrosis in experimental NASH in mice.

NOD-like receptor protein 3 (NLRP3) inflammasome activation occurs in Non-alcoholic fatty liver disease (NAFLD). We used the first small molecule NLRP3 inhibitor, MCC950, to test whether inflammasome blockade alters inflammatory recruitment and liver fibrosis in two murine models of steatohepatitis. We fed foz/foz and wild-type mice an atherogenic diet for 16weeks, gavaged MCC950 or vehicle until 24weeks, then determined NAFLD phenotype. In mice fed an methionine/choline deficient (MCD) diet, we gavaged MCC950 or vehicle for 6weeks and determined the effects on liver fibrosis. In vehicle-treated foz/foz mice, hepatic expression of NLRP3, pro-IL-1β, active caspase-1 and IL-1β increased at 24weeks, in association with cholesterol crystal formation and NASH pathology; plasma IL-1β, IL-6, MCP-1, ALT/AST all increased. MCC950 treatment normalized hepatic caspase 1 and IL-1β expression, plasma IL-1β, MCP-1 and IL-6, lowered ALT/AST, and reduced the severity of liver inflammation including designation as NASH pathology, and liver fibrosis. In vitro, cholesterol crystals activated Kupffer cells and macrophages to release IL-1β; MCC950 abolished this, and the associated neutrophil migration. MCD diet-fed mice developed fibrotic steatohepatitis; MCC950 suppressed the increase in hepatic caspase 1 and IL-1β, lowered numbers of macrophages and neutrophils in the liver, and improved liver fibrosis. MCC950, an NLRP3 selective inhibitor, improved NAFLD pathology and fibrosis in obese diabetic mice. This is potentially attributable to the blockade of cholesterol crystal-mediated NLRP3 activation in myeloid cells. MCC950 reduced liver fibrosis in MCD-fed mice. Targeting NLRP3 is a logical direction in pharmacotherapy of NASH. Fatty liver disease caused by being overweight with diabetes and a high risk of heart attack, termed non-alcoholic steatohepatitis (NASH), is the most common serious liver disease with no current treatment. There could be several causes of inflammation in NASH, but activation of a protein scaffold within cells termed the inflammasome (NLRP3) has been suggested to play a role. Here we show that cholesterol crystals could be one pathway to activate the inflammasome in NASH. We used a drug called MCC950, which has already been shown to block NLRP3 activation, in an attempt to reduce liver injury in NASH. This drug partly reversed liver inflammation, particularly in obese diabetic mice that most closely resembles the human context of NASH. In addition, such dampening of liver inflammation in NASH achieved with MCC950 partly reversed liver scarring, the process that links NASH to the development of cirrhosis.

Mridha AR ，Wree A ，Robertson AAB ，Yeh MM ，Johnson CD ，Van Rooyen DM ，Haczeyni F ，Teoh NC ，Savard C ，Ioannou GN ，Masters SL ，Schroder K ，Cooper MA ，Feldstein AE ，Farrell GC ... -  《-》