Correlation of urinary podocyte number and glomerular podocalyxin expression with clinicopathology in IgA nephropathy patients / 中华肾脏病杂志

ABSTRACT

Objective To examine the correlation of urinary podocyte number and giomerular podocalyxin expression with clinicopathology in IgA nephropathy(IgAN)patients. Methods Morning urinary specimens(100 ml)3 days before renal biopsy from 50 patients with IgAN diagnosed by renal biopsy and from 20 healthy volunteers as control were collected. After centrifugation, 300 μI sediment was used for smear. Immunohistochemical staining with monoclonal anti-podocalyxin antibody was performed to detect urinary podocytes and the number of podocyte was counted under optical microscope. Computer image analysis system was used to examine glomerular PCX expression. Renal pathology and classification were investigated based on Lee's grading and Katafuchi semi-quantitative integration method. Relevance analysis was carried out on urinary podocyte number, glomerular PCX expression with pathological score and clinical data. Results The amount of urinary podocytes in IgAN was obviously higher than that in healthy controls(P<0.01). Significant differences were found in multiple comparison of the median of urinary podocytes among Lee's grade groups. I - II group was lower as compared to Ⅲ , Ⅳ, Ⅴ groups(all P<0.05). Ⅲ group was lower as compared to V group(P<0.05). The positive rate of urinary podocyte was the highest in Ⅳ and V groups(100%), while the lowest in Ⅰ - Ⅱ group(55%). Glomerular PCX expression in IgAN decreased with the aggravation of renal pathology. Significant differences were found in multiple comparison of the glomerular PCX expression with the pathological score. Lee's Ⅰ - Ⅱ group was higher as compared to Ⅲ, Ⅳ, Ⅴ groups(all P<0.05). Ⅳ and Ⅳ groups were higher as compared to V group(P<0.05). In IgAN, urinary podocyte excretion was negatively correlated with glomerular PCX expression(r=-0.702, P<0.01), positively correlated with 24-hour urinary protein(r=0.465, P<0.01)and positively correlated with glomerular and tubular scores(r=0.233, 0.307, P<0.05). Glomerular PCX expression was negatively correlated with 24-hour urinary protein(r=-0.367,P<0.05)and negatively correlated with glomerular and tubular scores(r =-0.560, -0.377, P <0.05). Conclusions Injury and desquamation of glomerular podocytes may involve in the development of IgAN. The number of urinary podocyte can reflect the loss of podocytes in renal tissue, which may be used as a marker of disease progression of IgAN.