The Effects Of β-adrenoceptor Signal On Dendritic Cells And Fibroblast-like Synoviocytes From Adjuvant-induced Arthritis Rats

Adrenergic receptors (AR), which are the key part of nerve immunity receptors,may be involved in the occurrence and development process of rheumatoid arthritis(RA). Dendritic cells (DCs) as a powerful antigen presenting cells, plays an importantrole in regulating the immune response. DCs may be involved in the pathogenesis ofRA in the following several aspects: DCs can activate MHC restricted autoimmunereaction in the lymphatic organs, and induct immune response；DCs infiltrated into thesynovial membrane and synovial fluid in the joints, and uptake, process and presentantigen; DCs, FLS, macrophages produce inflammatory mediators, further stimulatedthe RA inflammatory immune response, etc. Fibroblast-like synoviocytes (FLS) ismajor effector cells of rheumatoid arthritis. Abnormal FLS proliferation and secretionof IL-1β, TNF-α and RANKL inflammatory cytokines, contributed to the localinflammatory response. AR are expressed on DCs and FLS, which are likely toparticipate in the neural immune regulation of RA, especially the β-AR signal mayhave immunomodulatory effects. This subject adopts the model of adjuvant arthritisrats, and use flow cytometry, QRT-PCR, immunofluorescence, and western blotmethod, and discussed the effects of β-adrenoceptor signal on dendritic cell andfibroblast-like synoviocytes from adjuvant-induced arthritis rats, which provide newclues to reveal the abnormal immune response pathogenesis of RA. Objective: To observe the function of β-AR signal on rats DCs and FLS, anddiscussion on the β-AR signal change of AA rats DCs and FLS and influence on itsfunction,which reveal the mechanism of β-AR signal transduction involved in thepathogenesis of RA abnormal inflammatory immune response, and provide animportant basis for new drug targets.Methods:Rat bone marrow cells were stimulated by rIL-4, rGM-CSF, which induced DCs;Using flow cytometry to detect DCs phenotypic CD80, CD86, MHC-Ⅱand antigenuptake function, and the expression of β2-AR on FLS; FLS and T cell proliferation ofMLR was determined by MTT method; The levels of IL-1β, IL-10, TNF-α, RANKL,OPG and cAMP was detected by ELISA; Making AA model by complete freund’sadjuvant, paw swelling degree was measured by Paw Volume Meter, joint pathologywere observed by HE dyeing; Detecting β2-AR distribution on DCs and FLS byimmunohistochemical method; The distribution of β2-AR on FLS was detected byimmunofluorescence; The expression of β2-AR, GRK2, β-arrestin2in the cellmembrane and p-ERK were detected by Western blot. The expression of β2-ARmRNA、GRK2mRNA were detected by QRT-PCR.Results:1. The effects of β-adrenoceptor signal on DCs from AA ratsβ-adrenergic agonists ISO obviously reduced the expression of CD86, MHC-Ⅱ,and does not affect the expression of CD80; ISO obviously increased the antigenuptake function of DCs and secreted levels of IL-10, and inhibited MLR. ISO affectedthe expression of CD86mainly through β1-AR signal; ISO reduced the expression ofMHC-Ⅱ, influenced the antigen uptake function and MLR effect through theβ2-ARsignal. β2-AR agonist salbutamol intragastric administration can significantly lowerthe expression of MHC-II, and improve the antigen uptake function of DCs, but therewas no significant effect on the expression of CD80and CD86; salbutamol cansignificantly decreased the AA rat paw swelling degree, and improve abnormal jointspathology; significantly reduced the AA rat thymus index and spleen index, andinhibited the proliferation of T lymphocyte, but there was no significant effect on the proliferation of B lymphocyte.The inhibition effect of ISO on T cell proliferation significantly lower in bonemarrow DCs from AA model group than normal group; the expression of β2-AR incell membrane obviously decreased in DCs from AA model rats by Western blot. Theexpression of β2-AR significantly decreased and the expression of GRK2significantlyincreased on d21, d28; there were no significant change in β2-AR mRNA and GRK2mRNA.2. The effects of β-adrenoceptor signal on FLS from AA ratsISO can significantly inhibit FLS proliferation, inhibit the secretion of IL-1β,TNF-α and RANKL level, and promote the secretion of OPG levels; its effect ofinhibition proliferation mainly through the β2-AR signal. β2-AR agonist salbutamolintragastric administration can significantly inhibit FLS proliferation.The expression of β2-AR in AA rats FLS cell membrane decreased significantly,desensitization effect is significantly higher than normal control group afterstimulated by ISO. The expression of GRK2and β-arrestin2in AA rats FLS cellmembrane significantly increased. The cAMP levels significantly decreased in AAmodel group; cAMP levels were significantly increased in control group and AAmodel group after ISO stimulation, but the cAMP level were significantly lower inAA model group than the control group. p-ERK level increased significantly in AAmodel group FLS, p-ERK level is significantly higher in AA model group than thecontrol group after ISO stimulation; ISO significantly increased the levels p-ERK inAA model FLS compared with no stimulation, and no obvious effect on the controlgroup.Conclusion:1. β2-AR signal involved in the regulation of DCs and FLS.The antigen uptake function and antigen presentation of DCs were mediated byβ2-AR signal; The inhibition effects on FLS proliferation mainly through β2-ARsignal stimulated by ISO.2. The abnormalities of β2-AR signal in AA rats DCs and FLS may be the reason whythere are differences on the agonist. The expression of β2-AR in membrane in AA rats DCs and FLS decreased,which may lead to the difference in reaction to the ISO; GRK2, β-arrestin2transfermembrane increased, which resulted in the enhancement of β2-AR desensitization,and led to a decline in membrane expression of β2-AR. β-arrestin2transfer membraneincreased, which resulted in the enhancement of p-ERK, and led to a decline reactionto the ISO.