The peritubular microangiopathic lesions caused by aristolochic acid and the expression of vascular endothelial growth factor in rats / 解放军医学杂志

ABSTRACT

Objective To investigate the pathological characters of capillaries in tubulointerstitial nephropathy,and to study the expression of vascular endothelial growth factor(VEGF)and proliferation cell nuclear antigen(PCNA)in capillary endothelial cells in aristolochic acid-induced nephropathy in rat.Methods 46 male Wistar rats were randomly divided into 2 groups,the model group was composed of 26 rats which were gavaged with the extract of Caulis Aristolochiae Manshuriensis(aristolochic acid AA 20mg/kg?d),and the control group consisted of 20 rats which were treated with equal volume of potable water.The rats were sacrificed in batches at the end of 4th,8th and 12th weeks,and the blood samples were collected from abdominal aorta for the tests of renal functions.The kidney of each rat was harvested.The renal tissues were stained with HE,PAS,and Masson's technique for the analysis of degree of tubulointerstitial injury,interstitial fibrosis,and peritubular capillary(PTC),and the expressions of both VEGF and PCNA were morphologically observed and immunohistochemically analyzed.Results In the model group,the level of serum creatinine/body weight increased markedly,the renal pathological changes consisted of severe acute renal tubulointerstitial damage with cloudy swelling of tubule,degeneration,and exfoliation.With prolongation of feeding time,the damage progressively aggravated,and showed a remarkable tubulointerstitial injury.The interstitial fibrosis area was 31.36% at the end of 12th week.The renal capillaries showed thickening of vessel wall,narrowing of the vessel cavity,obstruction or hyalinization of some capillaries.There was focal infiltration of inflammatory cells around the injured vessels.But there was no apparent change in the globules compared with that in control group.The PTC dwindled in caliber or distorted,and the PTC density decreased significantly in models,especially in the region of tubular damage or interstitial fibrosis.The expression of VEGF showed compensatory up-regulation at the 4th week,but it was down-regulated gradually.The expression of PCNA was up-regulated at the 4th week,but down-regulated after 8th week,and only a few basement membrane naked tubular cells showed positive expression at 12th week.Conclusion AA could induce injury and loss of capillaries of the kidney.The decrease in capillary density might contribute to the impairment of renal function and progressive interstitial fibrosis,and the relative deficiency of VEGF expression may be related to PTC injury,which is one of the causes of chronic progression of aristolochic acid nephropathy.