Gene therapy in a murine model of diabetic nephropathy using rAAV-esRAGE-mediated gene delivery.

BACKGROUND: Activation of innate immunity has been postulated as a key driver of complications of diabetes, including nephropathy. Receptors for advanced glycation end-products (RAGE) are expressed within diabetic kidneys and are one pathway of innate activation that has been demonstrated to contribute to nephropathy. AGE formation is increased in diabetes mellitus and therefore AGE-RAGE interaction is one likely activator of innate immunity in nephropathy. RAGE may also be activated by other endogenous ligands expressed in kidney, such as the Toll-like receptor (TLR)-ligand High-mobility group B1 (HMGB1). The aim of this study was to evaluate whether recombinant adeno-associated virus (rAAV2/8) expressing esRAGE (endogenous soluble RAGE) would act as a decoy receptor for AGE and HMGB1 and thereby diminish innate immune activation in kidney caused by AGE-RAGE, HMGB1-RAGE and HMGB1-TLR signalling. METHODS: Streptozocin-induced diabetic (n=7) and non-diabetic (n=5) BALB/c mice were treated with rAAV-esRAGE to induce esRAGE expression in hepatocytes. Additional controls included diabetic and non-diabetic mice treated with rAAV-HSA (human serum albumin) or no treatment. Five weeks after vector administration, the animals were sacrificed. Urine, blood, kidney, spleen and pancreas were collected for analysis. esRAGE expression was verified by ELISA. RESULTS: Mice administered with rAAV-esRAGE developed demonstrable levels of esRAGE, which were not detectable in controls. The rAAV-esRAGE treated diabetic animals showed increased levels of fibrosis (p