Celastrol ameliorates Propionibacterium acnes/LPS-induced liver damage and MSU-induced gouty arthritis via inhibiting K63 deubiquitination of NLRP3.

Celastrol, a pentacyclic triterpenoid quinonemethide isolated from several spp. of Celastraceae family, exhibits anti-inflammatory activities in a variety of diseases including arthritis. This study aims to investigate whether the inhibition of NLRP3 inflammasome is engaged in the anti-inflammatory activities of celastrol and delineate the underlying mechanism. The influence of celastrol on NLRP3 inflammasome activation was firstly studied in lipopolysaccharide (LPS)-primed mouse bone marrow-derived macrophages (BMDMs) and phorbol 12-myristate 13-acetate (PMA)-primed THP-1 cells treated with nigericin. Reconstituted inflammasome was also established by co-transfecting NLRP3, ASC, pro-caspase-1 and pro-IL-1β in HEK293T cells. The changes of inflammasome components including NLRP3, ASC, pro-caspase-1/caspase-1 and pro-IL-1β/IL-1β were examined by enzyme-linked immunosorbent assay (ELISA), western blotting and immunofluorescence. Furthermore, Propionibacterium acnes (P. acnes)/LPS-induced liver injury and monosodium urate (MSU)-induced gouty arthritis in mice were employed in vivo to validate the inhibitory effect of celastrol on NLRP3 inflammasome. Celastrol significantly suppressed the cleavage of pro-caspase-1 and pro-IL-1β, while not affecting the protein expressions of NLRP3, ASC, pro-caspase-1 and pro-IL-1β in THP-1 cells, BMDMs and HEK293T cells. Celastrol suppressed NLRP3 inflammasome activation and alleviated P. acnes/LPS-induced liver damage and MSU-induced gouty arthritis. Mechanism study revealed that celastrol could interdict K63 deubiquitination of NLRP3, which may concern interaction of celastrol and BRCA1/BRCA2-containing complex subunit 3 (BRCC3), and thereby prohibited the formation of NLRP3, ASC and pro-caspase-1 complex to block the generation of mature IL-1β. Celastrol suppresses NLRP3 inflammasome activation in P. acnes/LPS-induced liver damage and MSU-induced gouty arthritis via inhibiting K63 deubiquitination of NLRP3, which presents a novel insight into inhibition of celastrol on NLRP3 inflammasome and provides more evidences for its application in the therapy of inflammation-related diseases.

Yan CY ，Ouyang SH ，Wang X ，Wu YP ，Sun WY ，Duan WJ ，Liang L ，Luo X ，Kurihara H ，Li YF ，He RR ... -  《-》

Curcumin ameliorates monosodium urate-induced gouty arthritis through Nod-like receptor 3 inflammasome mediation via inhibiting nuclear factor-kappa B signaling.

Monosodium urate (MSU) crystals-induced inflammation is a key initiator in gouty arthritis. Curcumin is an active ingredient possessing anti-inflammatory efficacy. But the underlying mechanism is not fully understood and its effect on gouty arthritis remains elusive. We evaluated the effects of curcumin on cell viability in primary rat abdominal macrophages with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). Then supernatants of MSU crystals-stimulated cells were collected and subjected to enzyme-linked immunosorbent assay for checking the modulation of curcumin on interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Meanwhile, cells were analyzed by using Western blot analysis and quantitative polymerase chain reaction (QPCR) to investigate the effects of curcumin on Nod-like receptor 3 (NLRP3) inflammasome/nuclear factor-kappa B (NF-κB) signaling. We also investigated the in vivo efficacy of curcumin with MSU-induced gouty arthritis rat models. Curcumin could reduce MSU crystals-induced IL-1β and TNF-α in vitro. Western blot analysis and QPCR results revealed that curcumin regulated the production of these cytokines by suppressing the expression of inflammasome key components, including NLRP3, caspase-1. Further studies showed that the suppressive efficacy of curcumin on inflammasome was mediated by inhibiting MSU-induced NF-κB signaling activation. Intraperitoneal administration of curcumin could ameliorate symptoms of MSU-induced gouty arthritis, including the joint circumference, infiltration of neutrophils in knee joints, and production of IL-1β, TNF-α, and elastase. Western blot analysis revealed that the levels of NLRP3, procaspase-1, caspase-1, pro-IL-1β, and IL-1β were downregulated by curcumin in vivo. These results indicated that curcumin could effectively ameliorate MSU crystal-induced gouty arthritis through NLRP3 inflammasome mediation via inhibiting NF-κB signaling both in vitro and in vivo, suggesting a promising active ingredient for the prevention and treatment of gouty arthritis.

Li X ，Xu DQ ，Sun DY ，Zhang T ，He X ，Xiao DM ... -  《-》

Baeckein E suppressed NLRP3 inflammasome activation through inhibiting both the priming and assembly procedure: Implications for gout therapy.

Baeckein E (BF-2) was isolated from the aerial parts of Baeckea frutescens L., which has a long history of use in traditional medicine in Southeast Asia to treat inflammatory disease. BF-2 was identified to have inhibitory activity on nucleotide oligomerization domain (NOD)-like receptor protein-3 inflammasome (NLRP3) activation. This study aimed to investigate the related signaling cascade of BF-2 in both lipopolysaccharides (LPS)/ATP induced pyroptosis in J774A.1 macrophages and its application in a mouse model of gout induced by monosodium urate crystal (MSU). The effect of BF-2 on NLRP3 inflammasome activation and gouty arthritis was studied in J774A.1 macrophages and male C57BL/6 mice. The J774A.1 macrophages were primed with LPS and stained by propidium iodide (PI) for cell pyroptosis detection. A gout mouse model was established by subcutaneous injection of MSU crystals into the hind paw of C57BL/6 mice. Mice were then randomly divided into different groups. The concentrations of IL-1β and IL-18 in both J774A.1 macrophage and gout mouse model were analyzed by ELISA. The NLRP3 inflammasome related protein expression was detected by western blot analysis. The inhibitory effects of BF-2 on NLRP3 inflammasome assembly were analyzed by immunoprecipitation assay. The roles of BF-2 in mitochondrial damage were imaged by Mito Tracker Green and Mito Tracker Red probes. The inhibitory effects of BF-2 on ROS production were imaged by DCF (2',7'-dichlorofluorescein diacetate) probe. The results demonstrated BF-2 could significantly suppress the cell pyroptosis and IL-1β secretion in macrophages. Furthermore, BF-2 significantly inhibited NLRP3 inflammasome activation and reduced ankle swelling in the gout mouse model. In detail, it alleviated mitochondrial damage mediated oxidative stress and inhibited the assembly of NLRP3 inflammasome by affecting the binding of pro-Caspase 1 and ASC. Moreover, BF-2 blocked NLRP3 activation by inhibiting the MAPK/NF-κB signaling pathways. Results demonstrated BF-2 inhibited NLRP3 inflammasome activation in both LPS primed macrophages and mouse model of gout through blocking MAPK/NF-κB signaling pathway and mitochondrial damage mediated oxidative stress. This study strongly suggests BF-2 could be a promising drug candidate against inflammatory diseases associated with NLRP3 inflammasome activation.

Lin X ，Wang H ，An X ，Zhang J ，Kuang J ，Hou J ，Yan M ... -  《-》

Doliroside A attenuates monosodium urate crystals-induced inflammation by targeting NLRP3 inflammasome.

Our previous study demonstrates that Dolichos falcata Klein (DF) ameliorates the gouty arthritis induced by monosodium urate (MSU) crystals, and one of the active components, doliroside A, contributed to the anti-gouty arthritis effect of DF according to the in vitro study. However, there is still little known about the potential beneficial effects and possible mechanism of action of doliroside A on gouty arthritis. Here, we investigated the underlying mechanism of action of doliroside A in vitro and the anti-inflammatory effects of doliroside A in vivo. Bone-marrow-derived macrophages were treated with doliroside A before or after lipopolysaccharide (LPS) and then stimulated with MSU crystals, nigericin and adenosine triphosphate (ATP). The expressions of proteins related to activation of nucleotide-binding domain and leucine-rich repeat containing protein 3 (NLRP3) inflammasome were analyzed. The results manifested that doliroside A (15, 30, 45 and 60 μM) suppressed both LPS-induced priming and inflammasome activation in macrophages. Moreover, doliroside A was administered to the rats treated by MSU crystals. The results demonstrated that doliroside A (10, 20 and 40 mg/kg) ameliorated the symptoms of gouty arthritis, decreased the levels of pro-inflammatory cytokines, and inhibited the expressions of caspase-1 and pro-interleukin-1β (pro-IL-1β) proteins in MSU crystals-treated rats. These findings indicate that doliroside A exhibits a prominent effect on ameliorating gouty arthritis induced by MSU crystals. The action of doliroside A on gouty arthritis exerts via inhibiting the activation of caspase-1 and IL-1β secretion by affecting both LPS-induced priming and inflammasome activation.

Wei H ，Hu C ，Xie J ，Yang C ，Zhao Y ，Guo Y ，Mei Z ，Chen L ，Lan Z ... -  《-》

NLRP3 inflammasome inhibitor cucurbitacin B suppresses gout arthritis in mice.

Xue Y ，Li R ，Fang P ，Ye ZQ ，Zhao Y ，Zhou Y ，Zhang KQ ，Li L ... -  《-》