IgA肾病患者尿足细胞数及肾组织podocalyxin表达与临床病理的相关分析

目的 探讨尿足细胞数和肾组织中足细胞顶膜区的特异性标记蛋白podocalyxin（PCX）的表达与IgA肾病(IgAN)患者临床和病理改变的关系。 方法 收集50例IgAN患者活检前3 d的每天晨尿和20例体检健康对照者的晨尿各100 ml，离心去上清于TXD3细胞离心涂片机上制成涂片。用抗人PCX单克隆抗体分别对尿沉渣涂片和肾组织切片进行免疫组化染色，于光学显微镜下计数尿足细胞排泄数，以及用计算机图像分析系统测量和计算肾小球PCX平均吸光度值。IgAN按Lee分级分成5组，并用Katafuchi半定量积分法记分。比较各组尿足细胞数和肾组织PCX平均吸光度值，并与各项病理指标评分和临床生化指标进行相关性分析。 结果 IgAN组尿中足细胞数显著高于健康对照组（P < 0.01）。IgAN Lee分级各组组间尿足细胞中位数两两比较，Ⅰ-Ⅱ级组低于Ⅲ、Ⅳ、Ⅴ级组（P < 0.05）；Ⅲ级组显著低于Ⅴ级组（P < 0.05）；Ⅲ级组低于Ⅳ级组和Ⅳ级组低于Ⅴ级组，但差异无统计学意义。尿足细胞阳性率在Ⅳ、Ⅴ级组最高（100%），在LeeⅠ-Ⅱ级组最低（55%）。IgAN患者随着Lee分级升高，肾小球足细胞PCX表达下调，两两比较结果显示，Ⅰ-Ⅱ级组显著高于Ⅲ、Ⅳ、Ⅴ级组（P < 0.05）；Ⅲ、Ⅳ级组显著高于Ⅴ级组（P < 0.05）；Ⅲ级组稍高于Ⅳ级组（P > 0.05）。IgAN患者尿足细胞排泄数与肾小球PCX表达量呈负相关（r = -0.702，P < 0.01)；与24 h尿蛋白量呈正相关（r = 0.465，P < 0.01）；与肾小球和肾小管病理积分均呈正相关（r = 0.233，r = 0.307，均P < 0.05）。肾小球PCX表达量分别与肾小球和肾小管病理积分呈负相关（r = -0.560，r = -0.377，均P < 0.05）；与24 h尿蛋白量呈负相关（r = -0.367，P < 0.05）。 结论 IgAN患者尿足细胞排泄量可反映肾组织足细胞缺失程度，肾小球足细胞损伤脱落可能参与IgAN的发生发展，其尿足细胞数有可能作为反映疾病进展的重要指标。

Correlation of urinary podocyte number and glomerular podocalyxin expression with clinicopathology in IgA nephropathy patients

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.