Prevention of diabetic nephropathy in mice by a diet low in glycoxidation products

Background. Reactive advanced glycation end products (AGEs), known to promote diabetic tissue damage, occur endogenously as well as in heated foods and are orally absorbed. The relative contribution of diet-derived AGEs to diabetic nephropathy (DN) remains unclear. Methods. We tested a standard mouse food (AIN-93G) found to be rich in AGEs (H-AGE diet) in parallel with a similar diet that contained six-fold lower AGE content (L-AGE), but equal calories, macromitrients, and micronutrients. Non-obese diabetic mice (NOD) with type I diabetes (TID) and db/db mice with type 2 diabetes (T2D) were randomly assigned to each formula for either 4 or 11 months, during which time renal parameters and AGE levels were assessed. Results. Compared to the progressive DN and short survival seen in NOD mice exposed to long-term H-AGE feeding, L-AGE-fed NOD mice developed minimal glomerular pathology and a modest increase in urinary albumin: creatinine ratio (p<0.005), and a significantly extended survival (p<0.0001), consistent with lower serum (p<0.025) and kidney AGEs (p<0.01). Also, in the 4-month study, and in contrast to the H-AGE-fed mice, L-A*E-fed NOD and dbldb mice exhibited low levels of renal cortex TGFfl-1 (p < 0.05), laminin 131 rnRNA (p < 0.01) and )cl IV collagen mRNA (p < 0.05) and protein, in concert with reduced serum and kidney AGEs (p < 0.05, respectively). Conclusion. Intake of high-level, food-derived AGEs is a major contributor to DN in T1D and T21) mice. Avoidance of dietary AGEs provides sustained protection against DN in mice; providing the rationale for similar studies in human diabetic patients.