Effect Of Angiopoietin-1 On Expression Of TSP-1 And PEDF In The Kidney Of Diabetic Rats

Objective:To observe the expressional changes of thrombospondin-1(TSP-1) and pigment epithelium-derived factor(PEDF) in renal tissue of diabetic rats, and investigate the effect of recombinant adenovirus angiopoietin-1(Ad-Ang-1) on these factors in this model.Methods:Ad-Ang-1 was first constructed and identified. Rat model of diabetic nephropathy was induced by a single intraperitioneal injection of streptozotocin. The subjects were divided into 4 groups:control group(n= 20), diabetic group(n=20), blank vector group(diabetic rat was only administrated with adenovirus vector at 8 week, n=20) and Ang-1 treated group(diabetic rat was only administrated with Ad-ang-1 at 8 week, n=20). The urinary protein, renal pathologic changes were respectively observed at 8th,12th,20th and 28th week. The expressional levels of TSP-1,PEDF protein and mRNA in renal tissue at the same time points were detected by immunohistochemistry and real-time PCR, respectively.Results:(1) The levels of urinary protein in three diabetic model groups was higher than that in the control group (P<0.05), but urinary protein at 20th and 28th week was lower in Ang-1 treated group than diabetic or blank vector group (P<0.05).(2) TSP-1 was mainly found in glomeruli and tubulointerstitium with immunohistochemistry. Immunostaining score and mRNA expression levels of TSP-1 in three model groups were higher than that in control group (P<0.05), with the peak levels at 20 week, and increased levels of TSP-1 in Ang-1 treated group were downregulated as compared with diabetic or blank vector groups (P＜0.05).(3) PEDF was mainly found in glomeruli and tubulointerstitium with immunohistochemistry. Immunostaining score and mRNA expression levels of PEDF in three model groups were lower than that in control group (P<0.05), with trend of progressive reduction, and decreased levels of PEDF in Ang-1 treated group were upregulated as compared with diabetic or blank vector groups (P<0.05). (4) The level of urinary protein was negatively correlated with immunstaining score of PEDF (r=—0.548, P＜0.001), and positively with immunstaining score of TSP-1(r=0.571, P<0.001). TSP-1 was negatively correlated with PEDF(r=-—0.666, P＜0.001)..Conclusion:The abnormal expression of TSP-1 and PEDF may play a part in the development of diabetic nephropathy. Renal protection of Ad-Ang-1 administration may be relate to improve abnormal levels PEDF and TSP-1 in diabetic kidney.