Rheumatoid arthritis(RA)is an autoimmune disease,which is characterized by synovial inflammation.Hyperplasia sublining macrophages found in synovium is an early hallmark of RA and effective treatment results in their diminution.However,the origin of these sublining macrophages in synovium(including infiltrated macrophages and tissue-resident macrophages)are still unknown both in animal models of arthritis and RA patients,let alone the differences and feature of these macrophages.In rheumatic synovium,macrophages are submitted to a large variety of micro-environmental signals which influence the phenotypic polarization and activation of macrophages.Understanding the mechanisms and functional consequences of the heterogeneous macrophages will contribute to confirm their potential role in synovial inflammation development.Furthermore,research on macrophage plasticity to soft-control their phenotypic polarization could lead to novel therapeutic approaches.
Rheumatoid arthritis(RA)is an autoimmune disease and is mainly characterized by abnormal proliferation of fibroblast-like synoviocytes(FLS).The up-regulated cellular membrane expression of G protein coupled receptor kinase 2(GRK2)of FLS plays a critical role in RA progression,the increase of GRK2 translocation activity promotes dysfunctional prostaglandin E4 receptor(EP4)signaling and FLS abnormal proliferation.Recently,although our group found that paeoniflorin-6’-O-benzene sulfonate(CP-25),a novel compound,could reverse FLS dysfunction via GRK2,little is known as to how GRK2 translocation activity is suppressed.Our findings revealed that GRK2 expression up-regulated and EP4 expression down-regulated in synovial tissues of RA patients and collagen-induced arthritis(CIA)rats,and prostaglandin E2(PGE2)level increased in arthritis.CP-25 could down-regulate GRK2 expression,up-regulate EP4 expression,and improve synovitis of CIA rats.CP-25 and GRK2 inhibitors(paroxetine or GSK180736 A)inhibited the abnormal proliferation of FLS in RA patients and CIA rats by down-regulating GRK2 translocation to EP4 receptor.The results of microscale thermophoresis(MST),cellular thermal shift assay,and inhibition of kinase activity assay indicated that CP-25 could directly target GRK2,increase the protein stability of GRK2 in cells,and inhibit GRK2 kinase activity.The docking of CP-25 and GRK2 suggested that the kinase domain of GRK2 might be an important active pocket for CP-25.G201,K220,K230,A321,and D335 in kinase domain of GRK2 might form hydrogen bonds with CP-25.Site-directed mutagenesis and co-immunoprecipitation assay further revealed that CP-25 down-regulated the interaction of GRK2 and EP4 via controlling the key amino acid residue of Ala321 of GRK2.Our data demonstrate that FLS proliferation is regulated by GRK2 translocation to EP4.Targeted inhibition of GRK2 kinase domain by CP-25 improves FLS function and represents an innovative drug for the treatment of RA by targeting GRK2.
OBJECTIVE Basic fibroblast growth factor(b FGF)and platelet-derived growth factor(PDGF)produced by hepatocellular carcinoma(HCC)cells are responsible for the cell growth.Accumulating evidence shows that insulin-like growth factor-binding protein-3(IGFBP-3)suppresses HCC cell proliferation in both IGF-dependent and independent manners.The present study is to investigate whether treatment with exogenous IGFBP-3 inhibits bF GF and PDGF production and the cell proliferation of HCC cells.METHODS Cell Counting Kit 8 assay were designed to detect HCC cell proliferation,transcription factor early growth response-1(EGR1)involving in IGFBP-3 regulation of b FGF and PDGF were detected by RT-PCR and Western blot assays.Western blot assay was adopted to detect the IGFBP-3 regulating insulin-like growth factor 1 receptor(IGF-1R)signaling pathway.RESULTS The present study demonstrates that IGFBP-3 suppressed IGF-1-induced b FGF and PDGF expression while it does not affect their expression in the absence of IGF-1.To delineate the underlying mechanism,Western-blot and RT-PCR assays confirmed that the transcription factor early growth response protein 1(EGR1)is involved in IGFBP-3 regulation of b FGF and PDGF.IGFBP-3 inhibition of type 1 insulin-like growth factor receptor(IGF1R),ERK and AKT activation is IGF-1-dependent.Furthermore,transient transfection with constitutively activated AKT or MEK partially blocks the IGFBP-3 inhibition of EGR1,b FGF and PDGF expression.CONCLUSION In conclusion,these findings suggest that IGFBP-3suppresses transcription of EGR1 and its target genes b FGF and PDGF through inhibiting IGF-1-dependent ERK and AKT activation.It demonstrates the importance of IGFBP-3 in the regulation of HCC cell proliferation,suggesting that IGFBP-3 could be a target for the treatment of HCC.
OBJECTIVE To investigated the regulatory effect of paeoniflorin-6′-O-benzene sulfonate(CP-25) on B cell activating factor(BAFF)/BAFF receptor-nuclear factor of kappa B(NF-κB) signaling in B cell of collagen induced-arthritis(CIA) mice.METHODS Mice CIA was induced by injection of typeⅡcollagen(CⅡ).The arthritis index(AI) and swollen joint count(SJC) were assessed,and histopathology of spleen and joints were observed.The percentage of B cells subsets,BAFF receptor expressions were analyzed by flow cytometry.BAFF and immunoglobulin(Ig) levels were measured by protein antibody array.The expressions of TRAF2,MKK3,MKK6,p-P38,and p-NF-κB65 in NF-κB signaling mediated by BAFF were analyzed by western blot.RESULTS CP-25 decreased AI and SJC,restored abnormal weights,reduced thymus index and spleen index,inhibited T/B cells proliferation,alleviated the histopathology of spleen and joints in CIA mice.CP-25 also reduced high levels of serum BAFF and immunoglobulin,decreased CD19+B cells,CD19+CD27+B cells,and CD19-CD27+CD138+plasma cells,inhibited BAFFR and TACI expressions,decreased the expressions of TRAF2,MKK3,MKK6,p-P38,and p-NF-κB65.Compared with biological agents etanercept and rituximab,CP-25 restored high T cells proliferation and percentages of B subsets to normal level,and recovered the high levels of IgA,IgD,IgG1,IgG2 a and high expressions molecules in NF-κB signaling to normal levels.The action intensity of rituximab and etanercept was more strong than CP-25.The inhibitor effects of rituximab and etanercept on AI and SJC,thymus index,proliferation of T cells and B cells subsets were strong,and down-regulated the indexes to under normal levels.CONCLUSION CP-25 might be a promising anti-inflammatory immune and regulation drug,which alleviated CIA and regulated the functions of B cells through BAFF/BAFF receptor-NF-κB signaling.
G protein coupled receptors(GPCRs)are transmembrane receptor proteins,which allow signals to transfer across membrane.GPCRs include a large number of receptors,different receptors mediated different signaling pathways of GPCRs-adenylyl cyclase(AC)-cyclic adenosine 3',5'-monophosphate(c AMP),including β2 adrenergic receptors(β2-ARs)-AC-c AMP signaling pathways,E-prostanoid2/4(EP2/4)-AC-cA MP signaling pathways.Regulatory proteins,such as G protein coupled receptor kinases(GRKs)andβ-arrestins,play important modulatory roles in GPCRs signaling pathway.GPCRs signaling pathway and regulatory proteins implicate the pathogenesis process of inflammatory and immune response.Rheumatoid arthritis(RA)is an autoimmune disease characterized by synovitis and accompanied with inflammatory and abnormal immune response.This article review the advances on GPCRs signaling pathway implicating in the inflammatory and immune response of RA.
