The Role Of Alternative Complement Pathway Overactivation In Malignant Nephrosclerosis

BackgroundMalignant nephrosclerosis is a critical renal emergency caused by malignant hypertension,and it is also one of the important causes of causing and promoting end-stage renal disease,progressed rapidly and the renal function deteriorates sharply.Clinically,it is often characterized by hypertension(diastolic blood pressure?130mmHg),renal insufficiency,hematuria,proteinuria and other target organ damage.Currently,it is believed that mechanical stretch and activation of the renin-angiotensin system(RAS)are key factors,but it is far from fully explaining the onset and development of malignant nephrosclerosis.In recent years,studies at home and abroad have found that changes in plasma levels of complement factor H and membrane attack complex in patients with malignant nephrosclerosis,complement activation products along the vasculature and glomerular capillary wall and multiple complement components and complement regulatory proteins are present in gene mutations.The endothelial cell injury is a key risk factor for malignant nephrosclerosis,and histopathological features are identical to atypical hemolytic uremic syndrome(aHUS).Overactivation of the complement alternative pathway is a key pathogenesis of aHUS.Whether the excessive activation of the complement alternative pathway is involved in malignant nephrosclerosis.Collectively,we hypothesized that overactivation of the complement alternative pathway may be involved in the development of malignant nephrosclerosis.In this study,we examined the role of complement pathway activation,the deposition of complement activation product on kidney tissue and its correlation with clinical indicators,further illustrating the role of complement pathway overactivation in malignant nephrosclerosis.we expected that this study may provide new treatment basis and therapeutic target for the disease.ObjectiveTo explore the role of alternative complement pathway overactivation in malignant nephrosclerosis and its correlation with clinical indicators.Methods1.Fifty patients with confirmed malignant nephrosclerosis in our hospital from September 2013 to March 2019 were enrolled.At the same time,twenty-five cases of time-zero renal biopsy were enrolled as control subjects.Double antibody sandwich enzyme linked immune sorbent assay(ELISA)was used to evaluated the plasma and urinary levels of complement factor B(Bb fragment),factor P,factor H,and C3a,C5a the end products of complement activation,at the same time its association with clinical feature was investigated.2.Specimen of renal biopsy and immunohistochemistry were used to assay the deposition of C5b-9?C4d and MBL the lectin pathway activation product.Using double immunofluorescence labeling method to assay the deposition of C5b-9 and CD34 the endothelial cell marker in the arterioles and glomerular capillary endothelial surface.Results1.The plasma levels of complement factor B,factor P,C3a and C5a in malignant nephrosclerosis were significantly higher than those in control subjects(p<0.05),however,factor H were lower than those in control subjects(p<0.01).2.Urinary B/urinary creatinine,urinary P/urinary creatinine,urinary C3a/urinary creatinine,urinary C5a/urinary creatinine in malignant nephrosclerosis were significantly higher than those in control subjects(p<0.05),while,urinary H/urinary creatinine were lower than those in control subjects(p<0.01).3.Correlation analysis:The plasma level of factor P were significantly related with 24h proteinuria in malignant nephrosclerosis(rs=0.465,p=0.001).The urinary B/urinary creatinine,urinary P/urinary creatinine and urinary C3a/urinary creatinine levels in malignant nephrosclerosis were significantly associated with serum creatinine(rs=0.483,p<0.001;rs=0.352,p=0.012;rs=0.319,p=0.024).The urinary H/urinary creatinine levels in malignant nephrosclerosis were negatively correlated with serum creatinine(rs=-0.299,p=0.035)and 24h proteinuria(rs=-0.342,p=0.015).The urinary C5a/urinary creatinine levels in malignant nephrosclerosis were significantly correlated with serum creatinine(rs=0.525,p<0.001)and 24h proteinuria(rs=0.496,p<0.001).4.Immunohistochemical staining,Double immunefluorescence staining:Immunohistochemical result showed that there were C5b-9 deposited in the arterioles and glomerular capillary wall and C4d deposited in the arterioles and glomerular in malignant nephrosclerosis,and no MBL.There were no C5b-9,C4d and MBL deposition in normal renal tissues.Meanwhile,the semi-quantitative showed that C5b-9 score were significantly correlated with serum creatinine(rs=0.791,p<0.001)and 24h proteinuria(rs=0.345,p=0.014).The double-labeling analysis of C5b-9 and CD34 show that the green fluorescent labeled C5b-9 and red fluorescent labeled CD34 deposited in the arterioles and glomerular capillary endothelial surface.5.Correlation analysis of complement alternative pathway activation factors(B and P)in plasma and urine with end-products of complement activation(C3a,C5a),and C5b-9 deposition intensity scores in malignant nephrosclerosis:Factor B in plasma was positively correlated with C3a(r=0.331,p=0.022),complement factor P is positively correlated with C5b-9 score(rs=0.300,p=0.034);Factor B in urine were all positively related to C3a,C5a and C5b-9 scores(rs=0.311,p=0.028;rs=0.465,p=0.001;rs=0.428,p=0.002),the complement factor P was also positively correlated with C3a and C5a(rs=0.307,p=0.030;rs=0.442,p=0.001).Conclusions1.Complement activation via the alternative pathway is participated in malignant nephrosclerosis and may be playing an important role in the onset of the disease.2.The degree of the activation of the alternative pathway were associated with the severity of malignant nephrosclerosis.