Lessons From the KK-Ay Mouse, a Spontaneous Animal Model for the Treatment of Human Type 2 Diabetic Nephropathy

Diabetic nephropathy is a major cause of end-stage kidney disease (ESKD) in patients with type 1 and type 2 diabetes throughout the world. In human glomeruli, expansion of diffuse mesangial matrices, exudative lesions and/or segmental nodular sclerosis are pathological features of diabetic nephropathy. There have been many reports on the pathogenesis and treatment of type 2 diabetes using various animal models. It appears that KK-Ay mice, especially in terms of their immunohistological findings, are a suitable animal model for human type 2 diabetic nephropathy. Many compounds have been reported to be advanced glycation end product (AGE) inhibitors such as aminoguanidine, angiotensin II receptor inhibitors and pyridoxamine, and these are useful in therapeutic interventions for reducing AGEs. Pyridoxamine ameliorates lipid peroxidation and insulin resistance in KK-Ay mice. Combination therapy with angiotensin converting inhibitors (ACE-I) and angiotensin II type 1 receptor blockers (ARB), including an ARB and 1,25-dihydroxyvitamin D3, i.e. anti-hypertensive and anti-reactive oxygen species effects, or with eicosapentaenoic acid (EPA), i.e. anti-microinflammation effect, have shown efficacy in the treatment of diabetic nephropathy in KK-Ay mice. It appears that KK-Ay mice are a useful spontaneous animal model for the evaluation of pathogenesis and treatment in patients with type 2 diabetic nephropathy.