The Study Of Signal Transducton Pathways And Related Mechanisms Involved In Vascular Cell Adhesion Molecule-1in Gouty Arthritis

Objective: To investigate whether monosodium urate (MSU) crystals couldinduce the production of VCAM-1(vascular cell adhesion molecule-1) inhuman synovial cells and its possible signaling transduction pathways andRelated Mechanisms.Methods:(1) Human synovial cells was isolated from synovial tissueexplants was stimulated with various doses of MSU crystals(700,1000,1400uM) for different time intervals(0,4,8,12,24,48h). Expression ofVCAM-1was determined by the immunohistochemical staining, andevaluated with Western blotting, the relations among the doses of MSUcrystals, the time of exposure and the level of VCAM-1were alsodetermined.(2)To explore the underlying mechanisms, the activation ofmitogen-activated protein kinases (MAPKs) and the down regulation of theperoxisome proliferator-activated receptor γ (PPAR-γ) in synovial cellswere evaluated after the treatment with MSU crystals. VCAM-1protein expression was also evaluated after the MAPKs were blocked withPD98059,SB203580,SP60012.(3)The rat model of urarthritis were created by injecting50ul MSU to theankle joint of rats.The swelling index and functions of the ankle joint wereevaluated for different time intervals(1,4,6,24,48h). Expression ofVCAM-1was also determined by the immunohistochemical staining.Synovial tissue of the rat ankle joint was taken for HE staining, and thecartilage was observed by scanning electron microscope.Results:(1)Compared to the control,different dose of MSU all couldup-regulate the expression of VCAM-1significantly in synovial cells(p<0.05),The peak value of the expression of VCAM-1in groups of1000,1400uM were significantly higher than that of700uM(p<0.05).Inboth groups of1000,1400uM, there is no significant difference betweenthe peak values of the expression of VCAM-1(p＞0.05).Exposures toMSU crystals induced VCAM-1expression in culture medium in a doseand time dependent manner, reaching a plateau at1000μM and24h.(2)After the treatment with MSU, the phosphorylations of the MAPKs(ERK,P38,JNK)were significantly higher than that of controls, theexpressions of the PPAR-γ was also significantly lower than that ofcontrol(sp<0.05).While inhibition of the activation of MAPKs (ERK,P38,JNK) blocked the increased expression of VCAM-1significantly(p<0.05).(3)The ankle joints of the rats in experimental groups were significantly swelling than that of controls(p＜0.05).Compared to the controls,theexpression of VCAM-1in experimental groups were higher,and thecartilage of the rat joints was also damaged in the experimental groups.Conclusion:(1)The present results demonstrated that MSU crystals couldinduce the VCAM-1expression in human synovial cells. Exposure ofhuman synovial cells to MSU crystals induced VCAM-1expression inculture medium in a dose and time dependent manner, reaching a plateau at1000μM and24h.(2)Both MAPKs and PPAR-γ signaling pathways regulated the inducedVCAM-1expression, MAPKs signaling pathways could up-regulate the theexpression of VCAM-1in human synovial cells, while PPAR-γ signalingpathway could down-regulate the the expression of VCAM-1in humansynovial cells to some extent.(3)In the rat model of urarthritis,MSU could induce the swelling anddisfunction of ankle joint, the expression of the VCAM-1in the ratsynovial cells, and also the lesion of the cartilage.