Ambroxol, a mucolytic agent, boosts HO-1, suppresses NF-κB, and decreases the susceptibility of the inflamed rat colon to apoptosis: A new treatment option for treating ulcerative colitis.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology that increases the risk of developing colorectal cancer and imposes a lifelong healthcare burden on millions of patients worldwide. Current treatment strategies are associated with significant risks and have been shown to be fairly effective. Hence, discovering new therapies that have better efficacy and safety profiles than currently exploited therapeutic strategies is challenging. It has been well delineated that NF-κB/Nrf2 crosstalk is a chief player in the interplay between oxidative stress and inflammation. Ambroxol hydrochloride, a mucolytic agent, has shown antioxidant and anti-inflammatory activity in humans and animals and has not yet been examined for the management of UC. Therefore, our approach was to investigate whether ambroxol could be effective to combat UC using the common acetic acid rat model. Interestingly, a high dose of oral ambroxol (200 mg/kg/day) reasonably improved the microscopic and macroscopic features of the injured colon. This was linked to low disease activity and a reduction in the colonic weight/length ratio. In the context of that, ambroxol boosted Nrf2 activity and upregulated HO-1 and catalase to augment the antioxidant defense against oxidative damage. Besides, ambroxol inactivated NF-κB signaling and its consequent target pro-inflammatory mediators, IL-6 and TNF-α. In contrast, IL-10 is upregulated. Consistent with these results, myeloperoxidase activity is suppressed. Moreover, ambroxol decreased the susceptibility of the injured colon to apoptosis. To conclude, our findings highlight the potential application of ambroxol to modify the progression of UC by its anti-inflammatory, antioxidant, and antiapoptotic properties.

The Supportive Role of NSC328382, a P2X7R Antagonist, in Enhancing the Inhibitory Effect of CRID3 on NLRP3 Inflammasome Activation in Rats with Dextran Sodium Sulfate-Induced Colitis.

PURPOSE: The NLRP3 inflammasome is a substantial component of the inflammation process. The complex pathogenesis of and the implication of a vast number of components in the inflammasome-activation pathway prompted us to search for compounds that have a wide therapeutic index and act at the level of multiple cellular targets. Although CRID3 blocks NLRP3 with high specificity in the laboratory, clinical trials of the compound reported weaker potency. METHODS: We used NSC328382, a P2X7R antagonist, as an adjunctive therapy and generated a strategy to potentiate the effects of CRID3 in rats with DSS-induced colitis. RESULTS: NSC328382/CRID3 combined therapy exhibited a significantly increased efficacy compared with either of the monotherapies. NSC328382/CRID3 was more efficient in 1) attenuating colon shortening and disease activity; 2) improving goblet cell density and both the macroscopic and microscopic scenario of the injured colon; 3) improving the antioxidant defense mechanisms of the inflamed colon against oxidative stress; and 4) mitigating the inflammation state by downregulating the proinflammatory cytokines. Pyroptotic cell death was also conspicuously restrained. Additionally, NSC328382 interrupted the MyD88/NF-κB axis. Moreover, NSC328382/CRID3 exhibited the ability to alter Th1/Th2 dominance. CONCLUSION: The clinical application of NSC328382/CRID3 may result in the generation of a novel approach for the treatment of IBDs.

BBG enhances OLT1177-induced NLRP3 inflammasome inactivation by targeting P2X7R/NLRP3 and MyD88/NF-κB signaling in DSS-induced colitis in rats.

Chronic ulceration of the colon is associated with the activation of TLR4/NF-κB and P2X7R/NLRP3 signaling pathways. We investigated the effect of individual or combined administration of BBG, a P2X7R blocker, and OLT1177, a selective NLRP3 inhibitor, in the dextran sodium sulfate-induced ulcerative colitis (UC) rat model. The ulcerative rats were treated orally with brilliant blue G (BBG) (50 mg/kg/day) or OLT1177 (200 mg/kg/day) or a combination of both. Myd88 and NF-κB levels were measured by ELISA, qRT-PCR, and immunohistochemical staining. Cytokines known to be associated with TLR4/NF-κB or P2X7R/NLRP3 signaling were measured by ELISA. P2X7R and NLRP3 expression were measured by ELISA and qRT-PCR. The administration of BBG or OLT1177 ameliorated the toxic effects of DSS on the colon as they restored normal colonic macroscopic and microscopic morphology. BBG administration, but not OLT1177, reduced the expression of Myd88, NF-κB, IL-6, and TNF-α in addition to lowering P2X7R and oxidative stress levels. Individual BBG or OLT1177 administration decreased NLRP3 inflammasome recruitment and subsequent activation of caspase-1, IL-1ß, and IL-18. However, the combined administration of OLT1177 with BBG potentiated its inhibitory effect on the NLRP3, which was reflected by the additional suppressive effect on caspase-1, IL-1ß, IL-18 levels. In conclusion, BBG/OLT1177 exhibited complementary effects and effectively ameliorated UC. This novel approach provides a basis for the clinical application of this combination for the treatment of IBDs and might also be promising for the pharmacological intervention of other NLRP3 inflammasome-dependent inflammatory conditions.

Vildagliptin, a DPP-4 inhibitor, attenuates carbon tetrachloride-induced liver fibrosis by targeting ERK1/2, p38α, and NF-κB signaling.

Mitogen-activated protein kinases (MAPKs) and nuclear factor (NF)-ĸB signaling have been recognized for their causal connection with liver fibrosis. Hence, it is encouraging to discover drugs that can modify the interactions between these signaling cascades. It has been suggested that glucagon-like peptide-1 receptors (GLP-1Rs) might have a role in the observed hepatoprotection of dipeptidyl peptidase-4 inhibitors other than vildagliptin (VLD). Consequently, we aimed to elucidate the mechanisms underlying its potential antifibrotic activity in a CCl4-intoxicated mouse model. VLD increased the percentage of viable CCl4-intoxicated primary rat hepatocytes in vitro. It also attenuated hepatic fibrosis, improved liver function, and prolonged survival of CCl4-intoxicated mice in a dose-dependent manner. This hepatoprotection might be mediated mainly through interference with extracellular signal-regulated protein kinase 1/2 phosphorylation, the most downstream signal of the MAPK pathway. In addition, VLD hepatoprotective activity could be partially mediated through inhibition of p38α phosphorylation and phosphorylation-induced NF-ĸB activation. As a result, VLD downregulated profibrogenic mediators, such as tumor necrosis factor α, transforming growth factor ß, tissue inhibitor of metalloproteinase 1 and platelet-derived growth factor BB. Consequently, decreased expression levels of fibrosis markers, such as hydroxyproline and α smooth muscle actin, were confirmed. VLD showed a strong trend toward increasing the antioxidant defense machinery of fibrotic tissue, and we confirmed that GLP-1Rs were not implicated in the observed hepatoprotection. Since VLD poses little risk of hypoglycemia and is a safe drug for patients with liver injury, it may be a hopeful candidate for adjuvant treatment of liver fibrosis in humans.

Celastrol augments sensitivity of NLRP3 to CP-456773 by modulating HSP-90 and inducing autophagy in dextran sodium sulphate-induced colitis in rats.

NLRP3, one of the HSP-90 clients, has been defined as a critical component of IBD. In a rat model of DSS-induced colitis, we investigated the anti-inflammatory potential of the combined therapy with CP-456773 (CP), an NLRP3 inhibitor, and celastrol (CSR), an NF-κB inhibitor. Our results revealed that the CSR/CP combined therapy (CCCT) attenuated colon shortening, DAI and MDI in addition to improvement of the colonic histological picture. Moreover, the CCCT increased the antioxidant defense machinery of the colonic tissue and decreased MPO activity. Furthermore, the inflammation markers such as TNF-α and IL-6 were downregulated. These effects might be attributed to the inhibitory effect of CSR on the priming step of the NLRP3 inflammasome activation by interrupting NF-κB signalling and inhibition of HSP-90 (at the protein and mRNA levels) along with inhibitory effect of CP on the expression of the NLRP3. These latter effects resulted in decreased tissue expression and activity of the caspase-1 and repressing the subsequent release of the active forms of IL-1ß and IL-18, hence, the pyroptosis process is restrained. Additionally, the CCCT resulted in inducing autophagy by AMPK/mTOR-dependent mechanisms leading to the accumulation of BECN1 protein and a significant decrease in the levels of p62 SQSTM1. The inhibitory effect on HSP-90 in conjunction with induction of autophagy suggest increased autophagic degradation of NLRP3. This novel approach provides a basis for the clinical application of this combination in IBD treatment and might also be promising for the pharmacological intervention of other NLRP3 inflammasome-dependent inflammatory conditions.