Tubulointerstitial Lesions In Lupus Nephritis And The Effect Of Anti-P-Selectin Monoclonal Antibody On Murine Lupus

System lupus erythematosus(SLE)is a prototypic autoimmune disease that is characterized by systemic chronic inflammation that can affect multiple major organ systems.Lupus nephritis(LN)is the most common severe manifestation of SLE,many patients progress to end-stage renal disease(ESRD).Recently,it was found that the severity of tubulointerstitial lesion(TIL)is an important factor affecting the prognosis of LN patients.Previous studies indicated that immune deposits localizing in peritubular capillaries,tubular basement membranes and interstitium produce an inflammatory reaction which contributes to the development of TIL.Furthermore,hypoxia in tubulointerstitium is a final common pathway to ESRD.P-selectin is a selectin member of cell adhesion molecules that are widely accepted as critical modulator for various biological processes including inflammation and immunity,mediating initial leukocyte adhesion to activated platelet and endothelium.We found that P-selectin was highly expressed in both plasma and renal tissue of LN patients at early stage of our work,in addition,P-selectin and its mediated dendritic cell infiltrating in interstitium may trigger inflammatory reaction and hypoxia in tubulointerstitium damage.Our study aims to reveal the relationship between TIL,clinical-pathological characteristics and prognosis in patients with LN and explore the effect of anti-P-selectin mAb on tubulointerstitial damage in murine LN,provide a new insight into future treatment of LN.In the first part of the study,we retrospectively analysed 350 patients with biopsyproven lupus nephritis in our center from January 2005 to August 2015.Tubulointerstitial lesions including interstitial inflammation,tubular atrophy and interstitial fibrosis were assessed by semiquantitative score.Compared the clinical,laboratory and histological parameters of different severity of TIL.Follow-up data were obtained and renal survival analysis was conducted to determine the risk factors associated with the occurrence of the doubling of serum creatinine,end stage renal disease or death in patients with lupus nephritis.Among 350 patients,298 patients(85.14%)had TIL,and 73 patients(20.86%)had moderate to severe TIL.The prevalence of interstitial inflammation,tubular atrophy,and interstitial fibrosis was 81.71%,58.86% and 60.29% respectively.As the degree of TIL aggravated,blood pressure,the level of serum uric acid,24 h urinary protein and tubuloproteinuria of LN patients increased,meanwhile renal function and hemoglobin decreased.However,the activity indices,such as anti-ds-DNA antibody and complement C3,C4 did not change with TIL.Moderate to severe TIL was more common in patients with class IV,and activity and chronicity index were higher.Interstitial inflammation,tubular atrophy and interstitial fibrosis were associated with each other,in addition,interstitial inflammation also showed significant association with active glomerular lesions,including capillary hyperplasia,leukocyte infiltration,karyorrhexis or fibrinoid necrosis and cellular crescents.While,interstitial fibrosis and tubular atrophy obviously correlated with chronic glomerular lesions,such as glomerular sclerosis and fibrous crescents.But sometimes TIL can occur independent of glomerular lesions,with 14.3% of LN patients with more prominent TIL and nil or milder glomerular injury.In the logistic regression analysis,interstitial inflammation was risk factor for both renal sufficiency(OR=3.075;95% CI=2.112-4.479,P<0.001)and acute kidney injury(OR=2.954,95% CI=1.945-4.484;P<0.001).During a mean follow-up of 49.35±28.36 months,12 patients died,10 patients reached doubling of serum creatinine or end stage renal disease and renal survival decreased in those with moderate-to-severe TIL.Cox regression models showed that male(HR=3.272 95%CI=1.500-7.140,P=0.003),continuous without remission(HR=19.631,95%CI=9.346-41.236,P<0.001)and interstitial chronicity scores(HR=1.638,95%CI=1.328-2.021,P<0.001)were independent risk factors for poor renal outcomes.Thus,in the future clinical work,we should not only focus on glomerular lesions,but should also pay more attention to tubulointerstitial lesions,comprehensively analyzing patients' conditions,taking aggressive and proper therapeutic measures to prevent chronic development and improve prognosis.In the second part of this work,female MRL/lpr mice which being the spontaneous model of lupus nephritis served as the research objects,to explore the effect of anti-Pselection mAb on renal injury,especially on tubulointerstitial lesions and the underlying mechanism.Our previous studies had showed widespread P-selectin expression in renal tissue of MRL/lpr mice,mainly distributing in tubulointerstitium.By anti-P-selectin monoclonal antibody(mAb)intervention,the expression of P-selectin was significantly decreased.Compared with saline-treated mice,urinary protein and urinary albumin to creatinine ratio(ACR)were much lower in anti-P-selectin mAb treated mice.In addition,the levels of serum creatinine(Scr)were obviously declined in anti-P-selectin mAb treated mice than those in saline-treated mice.There were no statistical differences in the levels of anti-dsDNA antibodies and complement C3 between two groups.In this study,we further found that anti-P-selectin mAb treated mice exhibited a significant improvement in tubulointerstitial lesions in comparison with saline-treated control.Moreover,the expression of hypoxia-inducible factor 1 alpha(HIF-1?),as well as gp91 phox and p22 phox,which being subunits of NAPDH oxidase,was actually down-regulated in renal tissues of MRL/lpr mice treated with anti-P-selectin mAb,however,CD31 marked peritubular capillary(PTC)density was elevated.Blood oxygen level–dependent magnetic resonance imaging(BOLD-MRI)showed that the mean R2* values of renal cortex and medulla were higher in anti-P-selectin mAb mice than those in saline-treated mice.These results indicated that intervention with anti-P-selectin mAb may attenuate tubulointerstitial injury,hypoxia and the loss of PTC to some extent in MRL/lpr mice,and might be an emerging therapeutic method on lupus nephritis.Further studies are still needed.In summary,we retrospectively analyzed the clinical and pathological data of lupus nephritis patients,and revealed that tubulointerstitial lesions were common in LN.Tubulointerstitial chronicity,particularly tubular atrophy,is a risk factor for poor prognosis of LN patients.We further investigated the effect of anti-P-selection mAb on renal damage in murine lupus nephritis and found inhibition of P-selectin may attenuate tubulointerstitial injury,which might be a therapeutic target in LN.