In vivo AAV delivery of glutathione reductase gene attenuates anti-aging gene klotho deficiency-induced kidney damage

OBJECTIVE: Klotho is an aging-suppressor gene which leads to accelerated aging when disrupted. This study was designed to investigate whether glutathione reductase (GR), a critical intracellular antioxidant enzyme, is involved in the pathogenesis of kidney damages associated with accelerated aging in Klotho-haplodeficient (KL(+/–)) mice. METHODS AND RESULTS: Klotho-haplodeficient (KL(+/–)) mice and WT mice were used. We found that Klotho haplodeficiency impaired kidney function as evidenced by significant increases in plasma urea and creatinine and a decrease in urinary creatinine in KL(+/–) mice. The expression and activity of GR was decreased significantly in renal tubular epithelial cells of KL(+/–) mice, suggesting that Klotho deficiency downregulated GR. We constructed adeno-associated virus 2 (AAV2) carrying GR full-length cDNA (AAV-GR). Interestingly, in vivo AAV-GR delivery significantly improved Klotho deficiency-induced renal functional impairment and structural remodeling. Furthermore, in vivo expression of GR rescued the downregulation of the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, which subsequently diminished oxidative damages in kidneys, as evidenced by significant decreases in renal 4-HNE expression and urinary 8-isoprostane levels in KL mice. CONCLUSION: This study provides the first evidence that Klotho deficiency-induced kidney damage may be partly attributed to downregulation of GR expression. In vivo delivery of AAV-GR may be a promising therapeutic approach for aging-related kidney damage.