Punicalagin ameliorates collagen-induced arthritis by downregulating M1 macrophage and pyroptosis via NF-κB signaling pathway.

Rheumatoid arthritis (RA) is a chronic inflammatory disease that eventually leads to disability. Inflammatory cell infiltration, severe joint breaking and systemic bone loss are the main clinical symptoms. In this study, we established a collagen-induced arthritis (CIA) model and found a large number of M1 macrophages and pyroptosis, which are important sources of proinflammatory cytokines. Punicalagin (PUN) is an active substance extracted from pomegranate peel. We found that it inhibited joint inflammation, cartilage damage and systemic bone destruction in CIA mice. PUN effectively alleviated the high expression of inflammatory cytokines in synovial tissue in vivo. PUN treatment shifted macrophages from the M1 phenotype to the M2 phenotype after stimulation with lipopolysaccharide (LPS) and interferon (IFN)-γ. The expression of inducible nitric oxide synthase (iNOS) and other proinflammatory cytokines released by M1 macrophages was decreased in the PUN treatment group. However, simultaneously, the expression of markers of anti-inflammatory M2 macrophages, such as arginase (Arg)-1 and interleukin (IL)-10, was increased. In addition, PUN treatment attenuated pyroptosis by downregulating the expression of NLRP3 and caspase-1, thereby preventing inflammatory cell death resulting from the release of IL-1β and IL-18. Mechanistically, PUN inhibited the activation of receptor activators of the nuclear factor-κB (NF-κB) signaling pathway, which contributes to M1 polarization and pyroptosis of macrophages. We concluded that PUN ameliorated pathological inflammation by inhibiting M1 phenotype polarization and pyroptosis and has great potential as a therapeutic treatment for human RA.

Ge G ，Bai J ，Wang Q ，Liang X ，Tao H ，Chen H ，Wei M ，Niu J ，Yang H ，Xu Y ，Hao Y ，Xue Y ，Geng D ... -  《-》

Polyphyllin I Ameliorates Collagen-Induced Arthritis by Suppressing the Inflammation Response in Macrophages Through the NF-κB Pathway.

Wang Q ，Zhou X ，Zhao Y ，Xiao J ，Lu Y ，Shi Q ，Wang Y ，Wang H ，Liang Q ... -  《Frontiers in Immunology》

The monomer derivative of paeoniflorin inhibits macrophage pyroptosis via regulating TLR4/ NLRP3/ GSDMD signaling pathway in adjuvant arthritis rats.

This study was aimed to investigate the effect of monomer derivative of paeoniflorin (MDP) on macrophage pyroptosis mediated by TLR4/NLRP3/GSDMD signaling pathway in adjuvant arthritis (AA) rats. Wistar rats were divided into normal group, AA model group, MDP (50 mg/kg) group and MTX (0.5 mg/kg) group. The expression of TLR4, NLRP3 and GSDMD in macrophage were detected by immunofluorescence assay. The expression of TLR4 and the ratio of macrophage pyroptosis were analyzed by flow cytometry. Cell morphology was observed by scanning electron microscopy. The cytokine levels of IL-18 and IL-1β were detected by ELISA. The expressions of proteins related to macrophage pyroptosis were detected by western blot. MDP has a therapeutic effect on rats AA by reducing the secondary inflammation and improving pathological changes. The results of X-ray imaging and ultrasound images showed that MDP could inhibit bone erosion, soft tissue swelling, and joint space narrowing. Macrophage pyroptosis was found in secondary inflammation of AA rats. The expressions of TLR4, MyD88, NLRP3, Caspase-1, ASC, and GSDMD-N in macrophage were increased, the levels of IL-18 and IL-1β were enhanced, and the morphology of pyroptosis could be observed. MDP could inhibit macrophage polarization and macrophage pyroptosis, and down-regulated the cytokine levels of IL-18 and IL-1β in AA rats. MDP could regulate the M1/M2 ratio, decreased the ratio of macrophage pyroptosis and down-regulated the expressions of TLR4, MyD88, NLRP3, Caspase-1, ASC, and GSDMD-N in vivo and in vitro. Abnormal activation of TLR4/NLRP3/GSDMD signaling pathway may be involved in macrophage pyroptosis in AA rats. The therapeutic effect of MDP on AA rats is related to the inhibition of macrophage pyroptosis by regulating the TLR4/NLRP3/GSDMD signaling pathway.

Xu L ，Wang H ，Yu QQ ，Ge JR ，Zhang XZ ，Mei D ，Liang FQ ，Cai XY ，Zhu Y ，Shu JL ，Tai Y ，Wei W ，Zhang LL ... -  《-》

Lonicerin alleviates the progression of experimental rheumatoid arthritis by downregulating M1 macrophages through the NF-κB signaling pathway.

The present study aimed to evaluate anti-rheumatoid arthritis (RA) effect of Lonicerin (LON), a safe compound with anti-inflammatory and immunomodulatory properties. Nevertheless, the exact role of LON in RA remains elusive. In this test, the anti-RA effect of LON was evaluated in collagen-induced arthritis (CIA) mouse model. Relevant parameters were measured during the experiment; ankle tissue and serum were collected at the end of the experiment for radiology, histopathology, and inflammation analysis. ELISA, qRT-PCR, immunofluorescence, and western blot were used to explore the effect of LON on the polarization of macrophages and related signal pathways. It was discovered that LON treatment attenuated the disease progression of CIA mice with lower paw swelling, clinical score, mobility, and inflammatory response. LON treatment significantly decreased M1 marker levels in CIA mice and LPS/IFN-γ-induced RAW264.7 cells, while slightly increasing M2 marker levels in CIA mice and IL-4-induced RAW264.7 cells. Mechanistically, LON attenuated the activation of the NF-κB signaling pathway, which contributes to M1 macrophage polarization and inflammasome activation. In addition, LON inhibited NLRP3 inflammasome activation in M1 macrophages, thereby reducing inflammation by inhibiting IL-1β and IL-18 release. These results indicated that LON might exert anti-RA effects by regulating the polarization of M1/M2 macrophage, especially by inhibiting macrophage polarization toward M1.

Yang X ，Qian H ，Meng J ，Jiang H ，Yuan T ，Yang S ，Luo Y ，Bao N ，Zhao J ，Wang D ... -  《-》

Wutou decoction attenuates the synovial inflammation of collagen-induced arthritis rats via regulating macrophage M1/M2 type polarization.

Thousands of years of clinical practice in the treatment of joint-related diseases support the efficacy and safety of Wutou decoction (WTD). Nevertheless, the lack of pharmacological evidence and unclear mechanisms make it difficult for WTD to become a recognized complementary therapy for the treatment of rheumatoid arthritis (RA). This study aimed to investigate the effect of WTD against synovial inflammation in RA and whether this effect depends on the regulation of macrophage polarization. Sprague-Dawley rats were used to establish the collagen-induced arthritis (CIA) model. WTD with low and high doses was administered for 45 days. RAW264.7 cells were stimulated by lipopolysaccharide (LPS) or interleukin (IL)-4 to polarize M1 and M2 macrophages, which were pre-treated with WTD extract for 4 h. The anti-arthritic and anti-inflammatory effects of WTD were studied using arthritis score, histopathological staining, immunostaining, and enzyme-linked immunosorbent assay (ELISA). The polarization state of RAW264.7 cells and related pro/anti-inflammatory cytokines was detected by ELISA, reverse transcription quantitative polymerase chain reaction and western blotting. Western blotting and immunofluorescence were used to investigate the effect of WTD on nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and peroxisome proliferator-activated receptors γ (PPARγ) activation both in vivo and in vitro. WTD significantly reduced the arthritis score and the pathological damage of the knee joint and decreased the expression of tumor necrosis factor alpha (TNF-α), IL-6 in serum, TNF-α, IL-1β, monocyte chemoattractant protein-1 (MCP-1), and matrix metalloproteinase-3 (MMP3) in the knee synovium. WTD inhibited M1 type polarization and promoted M2 type polarization, both in vitro and in vivo, and reduced the expression of pro-inflammatory cytokines while increasing the expression of anti-inflammatory cytokines. Experiments showed that WTD inhibited the phosphorylation of NF-κB and downstream p38 in the synovium of CIA rats and LPS-induced M1 type polarized RAW264.7 cells. In addition, PPARγ expression in the synovium of CIA rats was mainly located in the cytoplasm, and WTD treatment increased the nuclear translocation of PPARγ, which was further verified in RAW264.7 cells. NF-κB and PPARγ regulating M1 and M2 macrophage polarization and subsequent secretion of pro-inflammatory and anti-inflammatory cytokines are the underlying mechanisms of WTD that ameliorate RA synovial inflammation.

Lin W ，Shen P ，Huang Y ，Han L ，Ba X ，Huang Y ，Yan J ，Li T ，Xu L ，Qin K ，Chen Z ，Tu S ... -  《-》