Lignin-derived lignophenols attenuate oxidative and inflammatory damage to the kidney in streptozotocin-induced diabetic rats

This study investigated the effects of lignin-derived lignophenols (LPs) on the oxidative stress and infiltration of macrophages in the kidney of streptozotocin (STZ)-induced diabetic rats. The diabetic rats were divided into four groups with 0%, 0.11%, 0.33% and 1.0% LP diets. The vehicle-injected controls were given a commercial diet. At 5 weeks, superoxide (O(2)(-)) production, macrophage kinetics, the degree of fibrosis in glomeruli and mRNA expression for monocyte chemoattractant protein-1 (MCP-1) were examined. The NADPH-stimulated O(2)(-) levels in the kidney of the diabetic rats treated with 1.0% LP were significantly lower than those in untreated diabetic rats. The number of macrophages, levels of MCP-1 mRNA expression and degree of glomerular fibrosis increased in untreated LP and these levels were significantly lower in 1.0%LP-treated rats. The results suggested that LPs suppress the excess oxidative stress, the infiltration and activation of macrophages and the glomerular expansion in STZ-induced diabetic kidneys.