The significance of urinary podocytes in patients with active lupus nephritis

Objective To assess the significance of urinary podocyte and its possible implication as a marker of activity of lupus nephritis.Methods The presence of podocytes in urinary sendiment was detected with immunochemical staining using anti-podocalyxin antibody.The correlation of the number of urinary podocytes with activity index of renal pathological lesions,hematuria,and proteinuria was analyzed respectively.The proliferating podocytes in renal biopsy tissue and urine from patients with class 1V lupus nephritis were examined with double immunohistochemical staining.Results Thirty-one patients with lupus nephritis undergoing renal biopsy were enrolled into the study.Renal pathological findings of the patients could be classified into WHO class Ⅲ (25.8%),class Ⅳ (64.5%) and class V (9.7%).90% of the patients had positive urinary podocytes.The number of urinary podocytes was strongly and positively correlated with the severity of hematuria (r=0.639,P=0.000) and glomerular pathological activity index (r=0.487,P=0.014) in patients of class Ⅲ and class Ⅳ.The amount of proteuria was not correlated with pathological activity index,even though all the patients had proteuria.Furthermore,the number of urinary podocytes,the severity of hematuria and the amount of proteuria were all decreased after treatment with methyl prednisone,cyclophosphamide or mycophenolate mofetil.Interestingly,the urinary podocytes could disappear even before the remission of hematuria and proteuria after treatment.Proliferative podocytes were observed both in biopsied kidney tissue and urinary sendiments in patients of class IV.Conclusion The presence and the number of urinary podocytes can be used as a valuable marker to grade the activity of lupus nephritis and to evaluate the efficacy of steroid therapy.