Beneficial Effects of Olmesartan and Temocapril on Urinary Liver-Type Fatty Acid-Binding Protein Levels in Normotensive Patients With Immunoglobin A Nephropathy

Background Liver-type fatty acid-binding protein (L-FABP) is a clinical biomarker of tubulointerstitial damage, which plays an essential role in the progression of chronic kidney disease (CKD), including immunoglobin A (IgA) nephropathy. The effect of combination therapy with the angiotensin receptor blocker (ARB) and the angiotensin-converting enzyme inhibitor (ACEI) on CKD has not been elucidated. Methods Twenty-four normotensive patients with IgA nephropathy were randomly assigned to receive olmesartan 10 mg/day, temocapril 2 mg/day, or combination therapy with both drugs. Urinary levels of L-FABP as well as 8-hydroxydeoxyguanosine (8-OHdG) and protein excretion were measured before and after 3 months of treatment. The chronicity index and activity index were also assessed by histopathologic findings. Results Urinary levels of L-FABP and 8-OHdG were higher in patients with IgA nephropathy than in age-matched and sex-matched healthy controls (122.5 ± 25.5 v 6.4 ± 3.8 μg/g • creatinine, P< .001; and 22.6 ± 4.4 v 4.8 ± 1.4 ng/mg • creatinine, P< .01, respectively). Urinary levels of L-FABP were correlated with those of 8-OHdG (baseline, P = .0001; after 3 months, P = .008) and the severity of proteinuria (baseline, P = .0015; after 3 months, P = .0001). The percent reductions in urinary levels of L-FABP and 8-OHdG, protein excretion, and activity index after 3 months were greater in the combination therapy group, compared with each monotherapy group of olmesartan (P< .05) and temocapril (P< .05). Conclusions The data suggest that a combination therapy of ARB plus ACEI has a greater beneficial effect on renal injury compared with monotherapy using ARB or ACEI in normotensive patients with IgA nephropathy.