Supra-physiologic flux/production of methylglyoxal (MG) has emerged as an underlying cause of nephropathy in chronic type 1 diabetes mellitus (T1DM). This increased MG arises in part from a reduction in expression of its detoxifying enzyme, glyoxalase-I (Glo-I). Adeno-associated virus (AAV)-mediated gene transfer has materialized as a promising strategy to increase expression of deficit proteins in disease states. Here we compared the efficacies of AAV2/9 containing Glo-I driven by two promoters, endothelin-1 (AAV2/9-Endo-Glo-I) and cytomegalovirus (AAV2/9-CMV-GloI) to attenuate nephropathy in T1DM rat. After eight weeks of T1DM, urine production increased 4-fold, urine norepinephrine increased 2.5-fold, serum creatinine increased 4-fold, creatinine clearance decreased 4-fold, BUN increased 5-fold, and proteinuria increased 8-fold. Renal Glo-I protein was 50% lower, MG was 2.5-fold higher, and extravasation of albumin from peritubular and glomerular capillaries and fibrosis were prominent. TNF-α and NF-κB (p65) phosphorylation were increased 3-4 folds. A single bolus injection of AAV/2/9 Glo-I and AAV2/9-Glo-I (1.7×1012 viron particles/kg) ten days after T1DM onset blunted increases in water consumption and urine assayed eight weeks later. AAV2/9-Glo-I also attenuated increases in norepinephrine, creatinine, BUN, proteinuria, albumin extravasation from renal microvessels, fibrosis, MG, TNF-α, NF-κB, activation and increased creatinine clearance rate. The magnitudes of the effects were higher in AAV2/9-Endo-Glo-I injected rats in part to higher expression of Glo-I in tubules and reduced expression of the MG-synthesizing enzyme vascular adhesion protein-1 within glomeruli. These new data demonstrate that intravenous administration of AAV2/9-containing Glo-I after the onset of T1DM attenuated renal dysfunction in rats via multiple mechanisms involving reductions in sympatho-excitation, inflammation, microvascular leakage and fibrosis.
K. Bidasee: None. F.A. Alomar: None.
National Institutes of Health (P30GM103335); University of Nebraska Medical Center (GTRP 1053); UNeMed