Mucosa-associated-lymphoid-tissue lymphoma-translocation gene 1 (MALT1), a paracaspase and essential regulator for nuclear factor kB (NF-κB) activation, plays an important role in innate and adaptive immunity. Suppression of MALT1 protease activity with small molecule inhibitors showed promising efficacies in subtypes of B cell lymphoma and improvement in experimental autoimmune encephalomyelitis model. However, whether MALT1 inhibitors could ameliorate colitis remains unclear. In the present study, we examined the pharmacological effect of two specific MALT1 inhibitors MI-2 and mepazine on the dextran sulfate sodium (DSS)-induced experimental colitis in mice, followed by mechanistic analysis on NF-κB and NLRP3 inflammasome activation. Treatment with MI-2 and mepazine dose-dependently attenuated symptoms of colitis in mice, evidenced by reduction in the elevated disease activity index, the shortening of colon length as well as the histopathologic improvement. Moreover, protein and mRNA levels of DSS-induced proinflammatory cytokines in colon, including TNF, IL-1β, IL-6, IL-18, IL-17A and IFN-γ, were markedly suppressed by MALT1 inhibitors. The underlying mechanisms for the protective effect of MALT1 inhibitors in DSS-induced colitis may be attributed to its inhibition on NF-κB and NLRP3 inflammasome activation in macrophages. The in vitro study showed that MALT1 inhibitors decreased production of IL-1β/IL-18 in phorbol myristate acetate-differentiated THP-1 cells and bone marrow derived macrophage via suppressing the activation of NF-κB and NLRP3 inflammasome. Taken together, our results demonstrated that inhibition of the protease activity of MALT1 might be a viable strategy to treat inflammatory bowel disease and the NLRP3 inflammasome and NF-κB activation are critical components in MALT1 signaling cascades in this disease model.
Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a severe, life-threatening medical condition characterized by widespread inflammation in the lungs, and is a significant source of morbidity and mortality in the patient population. New therapies for the treatment of ALI are desperately needed. In the present study, we examined the effect of andrographolide sulfonate, a water-soluble form of andrographolide (trade name: Xi-Yan-Ping Injection), on lipopolysaccharide (LPS)-induced ALI and inflammation. Andrographolide sulfonate was administered by intraperitoneal injection to mice with LPS-induced ALI. LPS-induced airway inflammatory cell recruitment and lung histological alterations were significantly ameliorated by andrographolide sulfonate. Protein levels of pro-inflammatory cytokines in bronchoalveolar lavage fluid (BALF) and serum were reduced by andrographolide sulfonate administration. mRNA levels of pro-inflammatory cytokines in lung tissue were also suppressed. Moreover, andrographolide sulfonate markedly suppressed the activation of mitogen-activated protein kinase (MAPK) as well as p65 subunit of nuclear factor-κB (NF-κB). In summary, these results suggest that andrographolide sulfonate ameliorated LPS-induced ALI in mice by inhibiting NF-κB and MAPK-mediated inflammatory responses. Our study shows that water-soluble andrographolide sulfonate may represent a new therapeutic approach for treating inflammatory lung disorders.
Aberrant activation of the NLRP3 inflammasome contributes to the onset and progression of various inflammatory diseases, making it a highly desirable drug target. In this study, we screened a series of small compounds with anti-inflammatory activities and identified a novel NLRP3 inflammasome inhibitor, AI-44, a curcumin analogue that selectively inhibited signal 2 but not signal 1 of NLRP3 inflammasome activation. We demonstrated that AI-44 bound to peroxiredoxin 1 (PRDX1) and promoted the interaction of PRDX1 with pro-Caspase-1 (CASP1), which led to the suppression of association of pro-CASP1 and ASC. Consequently, the assembly of the NLRP3 inflammasome was interrupted, and the activation of CASP1 was inhibited. Knockdown of PRDX1 significantly abrogated the inhibitory effect of AI-44 on the NLRP3 inflammasome. Importantly, AI-44 alleviated LPS-induced endotoxemia in mice via suppressing NLRP3 inflammasome activation. Taken together, our work highlighted PRDX1 as a negative regulator of NLRP3 inflammasome activation and suggested AI-44 as a promising candidate compound for the treatment of sepsis or other NLRP3 inflammasome-driven diseases.
The semihydrogenation of phenylacetylene to styrene represents an important process for optimizing the polystyrene production and also a model reaction for the evaluation of selective hydrogenation catalysts. Although the alloying strategy and surface engineering for noble metal (particularly for Pd) catalysts can effectively inhibit the overhydrogenation of styrene, the selectivity of phenylacetylene semihydrogenation to styrene is generally below 95% near the full conversion. Here, we demonstrate the electronic modulation of Pd-based bimetallic nanocluster catalysts based on the strong metal−support interactions for improving the catalytic selectivity for phenylacetylene semihydrogenation. A series of Pd−M (M = Fe, Co, Ni, Cu, Ga) bimetallic nanoclusters of ∼2 nm are immobilized on mesoporous sulfur-doped carbon (meso_S−C) supports, which exhibit a high selectivity of >97% for the semihydrogenation of phenylacetylene to styrene. The strong interaction between metal and the meso_S−C supports enables the modulation of electronic structure of the bimetallic nanoparticles and thus leads to the selectivity enhancement for the phenylacetylene semihydrogenation.
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