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(i NOS)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-1βand 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.

Protective effects of sirtuin 3 on titanium particle-induced osteogenic inhibition by regulating the NLRP3 inflammasome via the GSK-3β/β-catenin signalling pathway

Periprosthetic osteolysis(PPO)remains the key factor in implant failure and subsequent revision surgery and is mainly triggered by wear particles.Previous studies have shown that inhibition of osteoblastic differentiation is the most widespread incident affecting the interface of trabecular and loosening prostheses.Additionally,the NLRP3 inflammasome is activated by prosthetic particles.Sirtuin3,an NAD+-dependent deacetylase of mitochondria,regulates the function of mitochondria in diverse activities.However,whether SIRT3 can mitigate wear debris-induced osteolysis by inhibiting the NLRP3 inflammasome and enhancing osteogenesis has not been previously reported.Therefore,we investigated the role of SIRT3 during the process of titanium(Ti)particle-induced osteolysis.We revealed that upregulated SIRT3 dramatically attenuated Ti particle-induced osteogenic inhibition through suppression of the NLRP3 inflammasome and improvement of osteogenesis in vivo and in vitro.Moreover,we found that SIRT3 interference in the process of Ti particle-induced osteolysis relied on the GSK-3β/β-catenin signalling pathway.Collectively,these findings indicated that SIRT3 may serve as a rational new treatment against debris-induced PPO by deacetylase-dependent inflammasome attenuation.