Molecular and clinical response to angiotensin II receptor antagonist in kidney transplant patients with chronic allograft nephropathy

Comparison of the effects of standard vs low-dose prolonged-release tacrolimus with or without ACEi/ARB on the histology and function of renal allografts

Targeting the renin-angiotensin system and optimizing tacrolimus exposure are both postulated to improve outcomes in renal transplant recipients (RTRs) by preventing interstitial fibrosis/tubular atrophy (IF/TA). In this multicenter, prospective, open-label controlled trial, adult de novo RTRs were randomized in a 2 × 2 design to low- vs standard-dose (LOW vs STD) prolonged-release tacrolimus and to angiotensin-converting enzyme inhibitors/angiotensin II receptor 1 blockers (ACEi/ARBs) vs other antihypertensive therapy (OAHT). There were 2 coprimary endpoints: the prevalence of IF/TA at month 6 and at month 24. IF/TA prevalence was similar for LOW vs STD tacrolimus at month 6 (36.8% vs 39.5%; P = .80) and ACEi/ARBs vs OAHT at month 24 (54.8% vs 58.2%; P = .33). IF/TA progression decreased significantly with LOW vs STD tacrolimus at month 24 (mean [SD] change, +0.42 [1.477] vs +1.10 [1.577]; P = .0039). Across the 4 treatment groups, LOW + ACEi/ARB patients exhibited the lowest mean IF/TA change and, compared with LOW + OAHT patients, experienced significantly delayed time to first T cell-mediated rejection. Renal function was stable from month 1 to month 24 in all treatment groups. No unexpected safety findings were detected. Coupled with LOW tacrolimus dosing, ACEi/ARBs appear to reduce IF/TA progression and delay rejection relative to reduced tacrolimus exposure without renin-angiotensin system blockade. ClinicalTrials.gov identifier: NCT00933231.

Renal allograft protection with angiotensin II type 1 receptor antagonists

The renal benefits of agents inhibiting the renin-angiotensin-aldosterone system in renal transplant recipients, i.e. preventing the development of chronic graft nephropathy, are supposed but not finally proven. In a double-blind, placebo-controlled, cross-over study, we evaluated the influence of losartan on surrogate markers of tubular injury, urine excretion of transforming growth factor beta-1 (TGF-beta1) and amino-terminal propeptide of type III procollagen (PIIINP) in 16 patients after transplantation. The patients received randomly either losartan (50-100 mg daily) or the beta-blocker carvedilol (12.5-25 mg) for 8 weeks, allowing a placebo washout between treatments. The target office through blood pressure (BP) was below 130/85 mmHg. The BP did not differ in the treatment periods. Losartan significantly decreased N-acetyl-beta-d-glucosaminidase and alfa-1 microglobulin excretion relative to placebo and carvedilol. Urine excretion of TGF-beta1 and PIIINP was significantly lower after losartan. In conclusion, losartan reduces urine excretion of proteins associated with tubular damage and graft fibrosis.