Suppression of NF-κB signaling and NLRP3 inflammasome activation in macrophages is responsible for the amelioration of experimental murine colitis by the natural compound fraxinellone.

Inflammatory bowel disease (IBD) affects millions of people worldwide. Although the etiology of this disease is uncertain, accumulating evidence indicates a key role for the activated mucosal immune system. In the present study, we examined the effects of the natural compound fraxinellone on dextran sulfate sodium (DSS)-induced colitis in mice, an animal model that mimics IBD. Treatment with fraxinellone significantly reduced weight loss and diarrhea in mice and alleviated the macroscopic and microscopic signs of the disease. In addition, the activities of myeloperoxidase and alkaline phosphatase were markedly suppressed, while the levels of glutathione were increased in colitis tissues following fraxinellone treatment. This compound also decreased the colonic levels of interleukin (IL)-1β, IL-6, IL-18 and tumor necrosis factor (TNF)-α in a concentration-dependent manner. These effects of fraxinellone in mice with experimental colitis were attributed to its inhibition of CD11b(+) macrophage infiltration. The mRNA levels of macrophage-related molecules in the colon, including intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2), were also markedly inhibited following fraxinellone treatment. The results from in vitro assays showed that fraxinellone significantly reduced lipopolysaccharide (LPS)-induced production of nitric oxide (NO), IL-1β and IL-18 as well as the activity of iNOS in both THP-1 cells and mouse primary peritoneal macrophages. The mechanisms responsible for these effects were attributed to the inhibitory role of fraxinellone in NF-κB signaling and NLRP3 inflammasome activation. Overall, our results support fraxinellone as a novel drug candidate in the treatment of colonic inflammation.

Wu XF ，Ouyang ZJ ，Feng LL ，Chen G ，Guo WJ ，Shen Y ，Wu XD ，Sun Y ，Xu Q ... -  《-》

Wogonoside protects against dextran sulfate sodium-induced experimental colitis in mice by inhibiting NF-κB and NLRP3 inflammasome activation.

Previous studies have demonstrated that wogonoside, the glucuronide metabolite of wogonin, has anti-inflammatory, anti-angiogenic and anticancer effects. However, the anti-inflammatory mechanism of wogonoside has not been fully elucidated. Recently, NLRP3 inflammasome has been reported to be correlated with inflammatory bowel disease for its ability to induce IL-1β release. Nevertheless, there are few drug candidates targeting NLRP3 inflammasome for this disease. In this study, we investigated the anti-inflammatory effect of wogonoside in dextran sulfate sodium (DSS)-induced murine colitis and further revealed the underlying mechanisms by targeting NF-κB and NLRP3 inflammasome. Wogonoside treatment dose-dependently attenuated DSS-induced body weight loss and colon length shortening. Moreover, wogonoside prevented DSS-induced colonic pathological damage, remarkably inhibited inflammatory cells infiltration and significantly decreased myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities. The production of pro-inflammatory mediators in serum and colon was also significantly reduced by wogonoside. The underlying mechanisms for the protective effect of wogonoside in DSS-induced colitis may be attributed to its inhibition on NF-κB and NLRP3 inflammasome activation in colons. Furthermore, wogonoside markedly decreased production of IL-1β, TNF-α and IL-6 and suppressed mRNA expression of pro-IL-1β and NLRP3 in phorbol myristate acetate (PMA)-differentiated monocytic THP-1 cells via inhibiting the activation of NF-κB and NLRP3 inflammasome. In conclusion, our study demonstrated that wogonoside may exert its anti-inflammatory effect via dual inhibition of NF-κB and NLRP3 inflammasome, suggesting that wogonoside might be a potential effective drug for inflammatory bowel diseases.

Sun Y ，Zhao Y ，Yao J ，Zhao L ，Wu Z ，Wang Y ，Pan D ，Miao H ，Guo Q ，Lu N ... -  《-》

MALT1 inhibitors prevent the development of DSS-induced experimental colitis in mice via inhibiting NF-κB and NLRP3 inflammasome activation.

Liu W ，Guo W ，Hang N ，Yang Y ，Wu X ，Shen Y ，Cao J ，Sun Y ，Xu Q ... -  《Oncotarget》

Dimethyl fumarate ameliorates dextran sulfate sodium-induced murine experimental colitis by activating Nrf2 and suppressing NLRP3 inflammasome activation.

In the present study, we examined the effects of dimethyl fumarate (DMF) on dextran sulfate sodium (DSS)-induced murine colitis, an animal model which mimics human IBD. Oral administration of DMF dose-dependently attenuated body weight loss, colon length shortening and colonic pathological damage including decreased myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities in DSS-treated mice. Increased glutathione (GSH) induced by DMF demonstrated its potential antioxidant capacity. In addition, Nrf2 and its downstream genes were markedly activated by DMF. Furthermore, protein and mRNA levels of pro-inflammatory cytokines, including IL-1β, TNF-α and IL-6 were markedly suppressed by DMF. At the same time, decreased activation of caspase-1 was detected in DMF-treated mice, indicating that the NLRP3 inflammasome activation was suppressed. The in vitro study verified a negative regulation of DMF and its intestinal metabolite on NLRP3 inflammasome. Moreover, the inhibitory effect was found to be mostly dependent on Nrf2 which decreased mitochondrial ROS (mROS) generation and mitochondrial DNA (mtDNA) release. Taken together, our results demonstrated the ability of DMF to inhibit NLRP3 inflammasome activation and its potential use in the treatment of NLRP3-associated diseases.

Liu X ，Zhou W ，Zhang X ，Lu P ，Du Q ，Tao L ，Ding Y ，Wang Y ，Hu R ... -  《-》

Canna x generalis L.H. Bailey rhizome extract ameliorates dextran sulfate sodium-induced colitis via modulating intestinal mucosal dysfunction, oxidative stress, inflammation, and TLR4/ NF-ҡB and NLRP3 inflammasome pathways.

Genus Canna is used in folk medicine as demulcent, diaphoretic, antipyretic, mild laxative and in gastrointestinal upsets therapy. Canna x generalis (CG) L.H. Bailey is traditionally used as anti-inflammatory, analgesic and antipyretic. Besides, CG is used in Ayurvedic medicines' preparations and in the treatment of boils, wounds, and abscess. Nevertheless, its anti-inflammatory effects against ulcerative colitis (UC) are not yet investigated. This study aimed to investigate the phytoconstituents of CG rhizome ethanol extract (CGE). Additionally, we aimed to comparatively evaluate its therapeutic effects and underlying mechanisms against the reference drug "sulphasalazine (SAS)" in dextran sodium sulfate (DSS)-induced UC in mice. Metabolic profiling of CG rhizomes was performed via UHPLC/qTOF-HRMS; the total phenolic, flavonoid and steroid contents were determined, and the main phytoconstituents were isolated and identified. Next, DSS-induced (4%) acute UC was established in C57BL/6 mice. DSS-induced mice were administered either CGE (100 and 200 mg/kg) or SAS (200 mg/kg) for 7 days. Body weight, colon length, disease activity index (DAI) and histopathological alterations in colon tissues were examined. Colon levels of oxidative stress (GSH, MDA, SOD and catalase) and pro-inflammatory [Myeloperoxidase (MPO), nitric oxide (NO), IL-1β, IL-12, TNF-α, and INF-γ] markers were colourimetrically determined. Serum levels of lipopolysaccharide (LPS) and relative mRNA expressions of occludin, TLR4 and ASC (Apoptosis-Associated Speck-Like Protein Containing CARD) using RT-PCR were measured. Protein levels of NLRP3 inflammasome and cleaved caspase-1 were determined by Western blot. Furthermore, immunohistochemical examinations of caspase-3, NF-ҡB and claudin-1 were performed. Major identified constituents of CGE were flavonoids, phenolic acids, phytosterols, beside five isolated phytoconstituents (β-sitosterol, triacontanol fatty alcohol, β-sitosterol-3-O-β-glucoside, rosmarinic acid, 6-O-p-coumaroyl-β-D-fructofuranosyl α-D-glucopyranoside). The percentage of the phenolic, flavonoid and steroid contents in CGE were 20.55, 6.74 and 98.09 μg of gallic acid, quercetin and β-sitosterol equivalents/mg extract, respectively. In DSS-induced mice, CGE treatment ameliorated DAI, body weight loss and colon shortening. CGE attenuated the DSS-induced colonic histopathological alternations, inflammatory cell infiltration and histological scores. CGE elevated GSH, SOD and catalase levels, and suppressed MDA, pro-inflammatory mediators (MPO and NO) as well as cytokines levels in colonic tissues. Moreover, CGE downregulated LPS/TLR4 signaling, caspase-3 and NF-ҡB expressions. CGE treatment inhibited NLRP3 signaling pathway as indicated by the suppression of the protein expression of NLRP3 and cleaved caspase-1, and the ASC mRNA expression in colonic tissues. Additionally, CGE restored tight junction proteins' (occludin and claudin-1) expressions. Our findings provided evidence for the therapeutic potential of CGE against UC. CGE restored intestinal mucosal barrier's integrity, mitigated oxidative stress, inflammatory cascade, as well as NF-ҡB/TLR4 and NLRP3 pathways activation in colonic tissues. Notably, CGE in a dose of 200 mg/kg was more effective in ameliorating DSS-induced UC as compared to SAS at the same dose.

Mahmoud TN ，El-Maadawy WH ，Kandil ZA ，Khalil H ，El-Fiky NM ，El Alfy TSMA ... -  《-》