ABSTRACT
Growing evidences indicate that high glucose toxicity-associated fibrotic effects play a pivotal role in diabetic nephropathy (DN). Tubular epithelial-myofibroblast transdifferentiation is a major hallmark of renal fibrosis event under diabetic stress. Roots of Glycyrrhiza uralensis (Radix glycyrrhizae) used as a sweetener and traditional Chinese medicine possess high potential for renal protection. In this study, a cell model for high glucose (HG) injury with HK-2 renal proximal tubular epithelial cell line and a type-II-diabetes model with Apoeem1/Narl /Narl mice was established and the beneficial effects of aqueous R. glycyrrhizae extract (RGE) was investigated. RGE-induced regulation on the high glucose-induced excessive production of TGF-ß1 and the Smad/Stat3 mechanisms of renal fibrosis were determined. HK-2 cells were challenged with 45 mM of high glucose for 48 hr. Following high glucose challenge, the cells were treated with 0.5, 1, and 1.5 mg/ml concentrations of RGE. The effect of RGE on DN was determined using high fructose diet-induced type-II-diabetes in Apoeem1/Narl /Narl mice models. Our results showed that RGE suppressed the expression of HG-induced TGFß signaling and associated fibrosis mechanism better than the pharmacological drug acarbose. These data suggest that RGE as a potential herbal supplement in attenuating fibrosis-associated diabetic nephropathy and a potential agent in diabetes treatments.
Subject(s)
Diabetic Nephropathies , Drugs, Chinese Herbal , Glycyrrhiza uralensis , Animals , Cell Line , Cell Transdifferentiation , Diabetic Nephropathies/drug therapy , Diabetic Nephropathies/metabolism , Drugs, Chinese Herbal/pharmacology , Fibrosis , Glucose , Glycyrrhiza uralensis/chemistry , Humans , Mice , Myofibroblasts/metabolism , Plant Extracts/pharmacology , Signal Transduction , Transforming Growth Factor beta1/genetics , Transforming Growth Factor beta1/metabolismABSTRACT
Pathological manifestations in either heart or kidney impact the function of the other and form the basis for the development of cardiorenal syndrome. However, the mechanism or factors involved in such scenario are not completely elucidated. In our study, to find the correlation between late fetal gene expression in diabetic hearts and their influence on diabetic nephropathy, we created a rat model with cardiac specific overexpression of IGF-IIRα, which is an alternative splicing variant of IGFIIR, expressed in pathological hearts. In this study, transgenic rats over expressing cardiac specific IGF-IIRα and non-transgenic animal models established in SD rats were administered with single dose of streptozotocin (STZ, 55 mg/Kg) to induce Type I diabetes. The correlation between IGF-IIRα and kidney damages were further determined based on their intensity of damage in the kidneys. The results show that cardiac specific overexpression of IGF-IIRα elevates the diabetes associated inflammation and morphological changes in the kidneys. The diabetic transgenic rats showed advancement in the pathological features such a renal tubular damage, collagen accumulation and enhancement in STAT3 associated mechanism of renal fibrosis. The results therefore show that that IGF-IIRα expression in the heart during pathological condition may worsen symptoms of diabetic nephropathy in rats.
