Salidroside Ameliorates Gouty Arthritis Through Inhibition Of COX-2 And 5-LOX-mediated Macrophage M1 Polarization

Background and objective:PGE2 and LTB4 are thought to be important mediators in gout.However,dual blockade of COX-2 and 5-LOX pathways has not been investigated in MSU crystal-induced gouty arthritis.Here,we investigated whether salidroside(Sal)alleviates gouty arthritis through inhibition of COX-2 and 5-LOX-mediated M1 macrophage polarization.Our results could lead to a novel strategy against gouty arthritis.Methods:? A rat model of acute gouty arthritis was established.7 rats in each group were intragastrically administered Sal(40 and 80 mg/kg)or pure water once daily for a week,starting 5 d before MSU crystal injection.For the control group,rats were injected normal saline into ankle joints and orally administered pure water.The circumference of the right ankle joints of rats was measured at 0,2,4,8,12,16,24,48 h after MSU crystal injection.Gait alteration was assessed at 24 h after MSU crystal injection.The synovial cavities were lavaged for leukocytes counts.?COX-2,5-LOX,M1 markers(TNF-?,iNOS,IL-1? and CD86),M2 markers(CD206 and Arg-1),type II collagen,aggrecan and matrix metalloproteinase-13 were measured by qPCR.p-STAT1 and NF-?B were detected by Western blot.PGE2,LTB4,Ml cytokines(TNF-? and IL-1?)and M2 cytokines(TGF-? and IL-10)were measured by ELISA.The nuclear translocation of p65 in MSU crystal-treated RAW264.7 macrophages and CD68+ iNOS+ macrophages in synovial tissue were detected by immunofluorescence.? The clod(100 mg/kg)liposomes were administrated intraperitoneally 1 h after MSU crystals were injected into the right ankle joints of rats.In another experiment,ZA(100 ?g/kg)liposomes were injected intravenously.Sal(80 mg/kg)was intragastrically administered once daily for a week.The circumference of the ankle joints,gait alteration and the number of leukocytes in synovial fluid were assessed.?Conditioned media from MSU alone,MSU plus Sal(150 and 300 ?M)or vehicle-treated NR8383 macrophages was injected into the right hind ankle joints of rats once daily for a week.The circumference of the ankle joints,gait alteration and the number of leukocytes in synovial fluid were assessed.Results:?Sal alleviated acute gouty arthritis induced by monosodium urate(MSU)in rats.?Sal skewed macrophage polarization away from M1 phenotype,accompanied by the decreased production of prostaglandin E2(PGE2)and leukotriene B4(LTB4)in synovial fluid.?Macrophage depletion decreased ankle swelling rate,gait score and histological score in acute gouty arthritis,but adding clodronate or zoledronic acid liposomes to Sal treatment failed to affect these parameters.?Intra-articular injection with conditioned media from MSU-treated macrophages increased ankle swelling rateand walking gait score in rats,which was attenuated by Sal.? Sal decreased levels of COX-2/PGE2 and 5-LOX/LTB4 in synovial fluid macrophages and MSU-treated RAW264.7 or NR8383 macrophages.In addition,it inhibited the activation of signal transducers and activators of transcription(STAT)1.Conversely,exogenous addition of PGE2 or LTB4,or overexpression of COX-2 or 5-LOX or STAT1 partially reversed Sal-induced inhibition of M1 macrophage polarization.Conclusion:Down-regulation of COX-2 and 5-LOX pathways by salidroside ameliorates gouty arthritis through inhibiting macrophage Ml polarization via STAT1 and NF-?B.Our results could provide new clues for the treatment of gouty arthritis with COX-2/5-LOX dual inhibitors.