Effect Of P-selectin Monoclonalantibody On Renal Injury In Lupus Nephritis And Evaluated By Functional MR Imaging Of Kidneys

Lupus nephritis(LN) is one of the most common secondary glomerulonephritis in our country.The clinical manifestations were proteinuria, hematuria, even nephrotic syndrome and renal insufficiency. In 2003 the International Association of Nephrology and renal pathology Society(ISN/ RPS) classified LN mainly on the basis of the glomerular lesions. In fact, 60%~70%patients with LN were suffered with renal tubular damage, interstitial inflammation and fibrosis in different degrees. The severity of tubulointerstitial lesions directly affects the progress and prognosis of LN.During the process of tubulointerstitial lesions in LN, immune injury may lead to renal vascular endothelial cells activation, renal tissue ischemia and hypoxia, reactive oxygen species(ROS)accumulation in the kidney. ROS, P-selectin and mitogen activated protein kinase induce neutrophil adhesion and aggregation, which can aggravate renal tubulointerstitial damage.P-selectin, a member of cell adhesion molecules, expressing on the surface of activated platelet /endothelial cell, is the key factor mediating neutrophils adhesion to vascular endothelial cells and rolling to the initial site of inflammation. P-selectin may play an important role in the tubulointerstitial lesions of LN.In this study, the functional magnetic resonance imaging(MRI) was used to investigate the changes in renal morphology and function of the LN animal model before and after treatment with anti-P-selectin monoclonal antibody(m Ab). The study evaluated the role of the functional MRI in dynamiclly monitoring renal lesions and therapeutic effects in LN patients and animal models.Moreover, the pathogenesis of tubulointerstitial lesions in LN and the effect of anti-P-selectin m Ab were explored.In the first part of this study, sixty-five patients with lupus nephritis and 16 healthy volunteers underwent coronal echo-planar DWI and BOLD MR imaging of the kidneys. The relation between the renal injury variables and the apparent diffusion coefficient(ADC) or R2* values were evaluated. The mean ADC values of kidneys in patients with LN were 2.40±0.25 x10-3mm2/ s,the mean R2* values of the renal cortex and medulla were 11.03±1.60/sec and 14.05±3.38/sec respectively, which were all significantly lower than the ADC and R2* values of kidneys in healthy volunteers(P=0.048,P=0.045 and P=0.008, respectively). In the patients with LN, the mean ADC values were correlated with e GFR(r=0.510, P<0.01). There was a negative correlation between the mean ADC values and renal pathology chronicity indexes(r=-0.249, P <0.05). The R2* values of the renal medulla were negatively correlated with 24 hours proteinuria(r=-0.244,P<0.05), the degree of tubulointerstitial lesions(r=-0.242, P<0.05). And 16 of 65 patients with LN underwent a repeat evaluation after induction therapy for 9 to 12 months. The ADC and R2*values of kidneys were significantly higher than those of pre-treatment in complete remission patients. The results demonstrated that the functional MR imaging may be used to non-invasively monitor the disease activity and evaluate therapeutic efficacy in lupus nephritis.In the second part of this study, MRL/lpr mice which being the spontaneous model of lupus nephritis served as the research objects. The levels of proteinuria, serum creatinine, anti ds-DNA antibody in MRL/lpr mice were significantly higher than those in C57BL/6 mice. Glomerular mesangial proliferation and basement membrane thickening, tubular epithelial cells damage,interstitial leukocytes infiltration, especially the large accumulation of inflammatory cells surrounding small vessels were observed from the age of 12 weeks. It was found that Hypoxyprobe TM-1, HIF-1 alpha and HO-1 distributed widely in the renal tissue of MRL/lpr mice by immunohistochemical analyses and Western blot, and closely associated with the renal tubulointerstitial lesions. The mean ADC values were negatively correlated with proteinuria and serum creatinine levels, while the mean R2*values being negatively correlated with the degree of tubulointerstitial lesions and the expression of hypoxia parameters. The results suggested that renal hypoxia is one of the key factors leading to renal tubulointerstitial lesion, and functional MRI may used to monitor renal hypoxia in LN.In the third part of this study, the expression of P-selectin protein and m RNA was found significantly up-regulated in renal tissue of MRL/lpr mice by immunohistochemical analyses,Western blot and real-time fluorescence quantitative PCR. The expression of Hypoxyprobe TM-1,HIF-1 alpha and HO-1 protein and m RNA was down-regulated in renal tissues of MRL/lpr mice after the early intervention with anti-P- selectin m Ab, and the renal tubulointerstitial lesions were attenuated accordingly. The mean R2* values were negatively correlated with the degree of tubulointerstitial lesions and the expression of hypoxia parameters. The results suggested that upregulation of P-selectin in renal tissue of LN may be involved in initiating renal tubulointerstitial inflammation and pathological injuries in the early stage of lupus nephtitis, and BOLD-MRI may dynamically monitor intra-renal oxygenation status.In conclusion, this study showed that renal hypoxia may be one of the key factors leading to tubulointerstitial lesions in lupus nephritis. Intervention with Anti-P-selectin m Ab may attenuate renal hypoxia and tubulointerstitial lesions. Functional MR imaging may be used to non-invasively monitor the disease activity, oxygenation status and evaluate therapeutic efficacy in lupus nephritis.