Peritubular micrangium injury in renal interstitial fibrotic rats

Objectives To observe peritubular micrangium injury in renal interstitial fibrosis of unilateral ureteral obstruction(UUO) rats.Methods Thirty males SD rats were randomly divided into sham-operated(SHAM) and UUO group with 15 rats for each group.Five rats in each group were sacrificed on day 7,14 and 21 after UUO or sham-operation.The kidney tissue of obstruction side was taken and was examined by morphological analysis.Apoptosis of tubular epithelial cells were examined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling,the expression of CD141 and vascular endothelial growth factor(VEGF) were detected by immunohistochemical method.Results In the SHAM group,there were no significant injury of peritubular capillary(PTC),and the numbers of CD141 positive PTC were(189.6±8.38)/mm2,(185.2±11.12)/mm2,(173.8±13.27)/mm2 on day 7,14,21.In the UUO group,PTC injured severely,the numbers of CD141 positive PTC were progressively decreased with(116.8±8.92)/mm2,(98.8±3.96)/mm2,(62.2±7.01)/mm2 on day 7,14,21 respectively.No tubular epithelial cells apoptosis was observed in SHAM group,while apoptosis was found in UUO group on day 7 after operation(P0.05).The number of apoptotic cells was increasing as the obstruction time getting longer.In SHAM group,there was no inflammatory cell infiltration observed with more VEGF presented in kidney tubular epithelial cell.While massive inflammatory cell infiltration was found in tubular interstitial area in UUO group on day 7 and increasing obviously on days 14 and 21 with decreasing VEGF protein.Nearly no VEGF protein was observed when infiltration became severe.Conclusions Renal peritubular capillary loss is positively correlated to interstitial fibrosis and plays an important role in interstitial fibrosis.