Combination Therapy with Benazepril and Oral Adsorbent Ameliorates Progressive Renal Fibrosis in Uremic Rats

Abstract

Background/Aims: The administration of an angiotensin-converting enzyme (ACE) inhibitor or an oral adsorbent, AST-120 (Kremezin), prevents the progression of renal failure. This study was designed to determine the additional effects of AST-120 combined with an ACE inhibitor, benazepril, on the progression of renal fibrosis in uremic rats. Methods: 5/6-nephrectomized uremic rats were divided into control uremic rats (CRF group), benazepril-treated uremic rats (CRF+B group) and uremic rats receiving benazepril and AST-120 (CRF+BK group). After 14 weeks of treatment renal function and pathological changes were investigated. Results: The progression of renal dysfunction was delayed in both the CRF+B and CRF+BK groups as compared with the CRF group. In the CRF+BK group, the level of serum and urinary indoxyl sulfate and the tubular accumulation of indoxyl sulfate decreased. Both the CRF+B and CRF+BK groups showed lower glomerular sclerosis indices than the CRF group. In the CRF+BK group, but not the CRF+B group, the interstitial fibrosis area and the expression of transforming growth factor (TGF) β1 and tissue inhibitor of metalloproteinases (TIMP) 1 were decreased as compared with the CRF group. Furthermore, the CRF+BK group showed a smaller interstitial fibrosis area and a lower renal osteopontin expression than the CRF+B group. Conclusion: Combination therapy of benazepril and AST-120 is more effective than benazepril alone in retarding the progression of interstitial fibrosis by reducing the expression of TGF-β1, TIMP-1 and osteopontin.