紫癜性肾炎患儿肾组织podocalyxin 的表达及其与尿足细胞数的相关分析

目的：分析肾脏足细胞特异蛋白podocalyxin(PCX) 的表达和尿足细胞数在紫癜性肾炎(Henoch-Schönlein purpura nephritis,HSPN) 病理进展过程中的变化。方法：56 例HSPN 患儿为病例组,根据肾脏病理改变分为4 组：HSPN II (IIa+IIb) 级组(n=10),III (IIIa+IIIb) 级组(n=21),Ⅳ级组(n=16) 和Ⅴ级组(n=9);另取非肾脏疾病死亡病例尸检切取的肾脏标本4 例作为正常肾组织对照组;同时收集8 例健康儿童的晨尿作正常尿液对照组。应用免疫荧光方法检测PCX 在4 例正常肾组织及56 例HSPN 肾组织中的表达,并对其结果进行定量分析;同时检测8 例健康儿童及56 例HSPN 患儿尿足细胞阳性的发生率和尿足细胞数。结果：在正常对照组和HSPN II (IIa+IIb) 级组的肾组织中,PCX 表达完整,2 组之间肾组织PCX 阳性面积占肾小球面积的百分比差异无统计学意义(P>0.05);在HSPN III(IIIa+IIIb) 级﹑Ⅳ级和Ⅴ级组的肾组织中,PCX 表达均有不同程度缺失,从III (IIIa+IIIb)~V 级其表达依次下降,各组间比较差异有统计学意义(P<0.01);病理分级在III (IIIa+IIIb)级以上的HSPN,尿中有PCX 的阳性表达,提示尿中有足细胞存在;肾组织PCX 荧光阳性面积占肾小球的百分比与尿中足细胞数呈负相关(r=-0.637,P<0.01)。结论：足细胞损伤在儿童HSPN 病理进展中发挥一定作用;可以在一定程度上反映HSPN 的病理损伤程度。

Podocalyxin expression in renal tissues and correlation with the number of urinary podocytes in children with Henoch-Schonlein purpura nephritis

Objective: To analyze the podocalyxin (PCX) expression in the kidney and the number of urinary podocytes in different pathological grades of Henoch-Schönlein purpura nephritis (HSPN), and to determine whether the number of urinary podocytes reflects the renal damage in HSPN. Methods: Fifty-six children diagnosed with HSPN in our hospital were enrolled in the study and classified into 4 groups by renal pathology: grade II (IIa+IIb) (n=10), grade III (IIIa+IIIb) (n=21), grade IV (n=16), and grade V (n=9). Four kidney autopsy specimens without histomorphologic lesions and 8 urine samples from healthy children served as controls. With immunofluorescence assay, the PCX expression in 4 normal renal tissues and in the renal tissues of the 56 HSPN children was detected and quantitatively analyzed. Positive rate and the number of urinary podocytes were detected in the 8 healthy children and 56 HSPN children. Results: In the renal tissues of the normal control group and grade II (IIa+IIb) HSPN group, the PCX expression was complete. The percentage of the PCX positive area out of the total glomerular area in the renal tissues of 2 groups had no significant difference (P>0.05). In the renal tissues of grade III (IIIa+IIIb), IV, and V HSPN groups, the PCX expression showed various degrees of loss, decreasing in turn from grade II (IIa+IIb), III (IIIa+IIIb), IV to V, with significant differences between each group (P<0.01). For HSPN with grade III (IIIa+IIIb) or higher, positive PCX expression was found in the urine, suggesting the presence of enough podocytes in the urine. The percentage of fluorescence positive area out of the total glomerular area of PCX in the renal tissues was negatively correlated with the total number of urinary podocytes (r=-0.637, P<0.01). Conclusion: Podocyte injury plays a certain role in the pathological progression of HSPN. The urinary detection of podocytes can reflect the degrees of pathological damage in HSPN.