Diabetes & Metabolism Journal

Original Articles

Activation of NF-kappaB and AP-1 in Peripheral Blood Mononuclear Cells Isolated from Patients with Diabetic Nephropathy.: Jisun Nam, Min Ho Cho, Jong Suk Park, Geun Taek Lee, Hai Jin Kim, Eun Seok Kang, Yu Mie Lee, Chul Woo Ahn, Bong Soo Cha, Eun Jig Lee, Sung Kil Lim, Kyung Rae Kim, Hun Joo Ha, Hyun Chul Lee; Korean Diabetes J. 2007;31(3):261-273. Published online May 1, 2007; DOI: https://doi.org/10.4093/jkda.2007.31.3.261

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Abstract PDF: BACKGROUND
We evaluated the role of oxidative stress in diabetic nephropathy by measuring intracellular reactive oxygen species (ROS) and redox-sensitive transcription factors in isolated peripheral mononuclear cells (PBMC). METHODS: From 66 diabetic patients with or without diabetic nephropathy (Group III and II, respectively) and 49 normal control subjects (Group I), spontaneous and stimulated ROS levels, activities of nuclear factor-kappa B (NF-kappaB), activator protein-1 (AP-1), and specificity protein1 (Sp1) in PBMC, urinary and PBMC TGF-beta1 (transforming growth factor-beta1), and 24-hour urinary albumin excretion (UAE) were measured. RESULTS: Spontaneous ROS was significantly higher in group III and II than group I (60.7 +/- 3.3 vs. 60.0 +/- 3.0 vs. 41.1 +/- 2.4%, respectively), and stimulated ROS were significantly higher in Group III compared to Group II (Increment of H2O2-induced ROS production: 21.8 +/- 2.2 vs. 11.1 +/- 2.0%, respectively; increment of PMA-induced ROS production 23.5 +/- 4.5 vs. 21.6 +/- 2.2%, respectively). The activities of NF-kappaB and AP-1, but not of Sp1, were significantly higher in Group III than in Group II (2.53 vs. 2.0 vs. 1.43-fold, respectively). Both PBMC- and urinary TGF-beta1 levels were higher in Group III than Group II (3.23 +/- 0.39 vs. 1.99 +/- 0.68 ng/mg in PBMCs, 16.88 +/- 6.84 vs. 5.61 +/- 1.57 ng/mL in urine, both respectively), and they were significantly correlated with activities of NF-kappaB and AP-1 and 24-hour UAE. CONCLUSIONS: Increased intracellular ROS generation in PBMCs of diabetic patients is involved in the pathogenesis of diabetic nephropathy through activation of NF-kappaB and AP-1, but not Sp1, and increased expression of TGF-beta1.

Effects of Troglitazone on the Expression of VEGF and TGF-beta in Cultured Rat Mesangial Cells.: Dong Lim Kim, Nan Hee Kim, Dong Seop Choi; Korean Diabetes J. 2007;31(3):220-229. Published online May 1, 2007; DOI: https://doi.org/10.4093/jkda.2007.31.3.220

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Abstract PDF: BACKGROUND
Clinical study reported that troglitazone ameliorated microalbuminuria in diabetic nephropathy. However, the mechanism of action is not fully understood. Vascular endothelial growth factor (VEGF) is known as vascular permeability factor and it is considered the most likely cause of glomerular hyperfiltration and proteinuria in diabetic nephropathy. Transforming growth factor-beta (TGF-beta) is a potent inducer of extracellular matrix production and fibrosis in renal cells and one of the important cytokine in the pathogenesis of diabetic nephropathy. To determine whether troglitazone affects VEGF and TGF-beta production in diabetic nephropathy, we examined the effects of troglitazone on the VEGF and TGF-beta expression in cultured rat mesangial cells exposed to high glucose concentration. METHODS: Rat mesangial cells were cultured in media with D-glucose 5.5 mM (NG) or D-glucose 30 mM (HG), or D-glucose 30 mM/troglitazone 20 micrometer(HTz) and for 6, 24, or 72 hours, respectively. VEGF and TGF-beta expression were assessed by semiquantitative RT-PCR and western blot analysis. RESULTS: Troglitazone decreased the VEGF164 and VEGF120 mRNA expressions in cultured rat mesangial cells exposed to high glucose concentration with incubation for 24 and 72 hours, respectively. VEGF protein was also decreased in experimental group treated with troglitazone (HTz) than in those with HG for 24 and 72 hours. However troglitazone had no effect on the expression of TGF-beta mRNA in mesangial cells. CONCLUSION: This study suggested that troglitazone may modulate the development and progression of diabetic nephropathy by reducing the expression of VEGF in mesangial cells

Transforming Growth Factor-beta 1 Gene Polymorphisms According to Diabetic Nephropathy in Type 2 Diabetes.: Hyun Jeong Jeon, Ok Hee Kim, Kil Ho, Soon Kil Kwon, Tae Keun Oh; Korean Diabetes J. 2007;31(2):144-150. Published online March 1, 2007; DOI: https://doi.org/10.4093/jkda.2007.31.2.144

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Abstract PDF: BACKGROUND
Transforming growth factor-beta is known to play a role in the interaction between metabolic and hemodynamic factors in mediating accumulation of extracellular matrix in the diabetic nephropathy. TGF-beta1 gene polymorphism was associated with circulating TGF-beta levels and influenced the pathogenesis of fibrotic diseases including diabetic nephropathy. In this study, we examined the relationship between TGF-beta1 gene codon 10 polymorphism and type 2 diabetic nephropathy with more than 10-year history of disease. METHODS: We conducted a case-control study, which enrolled 325 type 2 diabetes. A total of 176 patients with diabetic nephropathy were compared with 149 patients without diabetic nephropathy. TGF-beta1 codon 10 genotyping was determined using polymerase chain reaction with sequence specific primers method. RESULTS: Distribution of TGF-beta1 codon 10 genotype in the patients either with nephropathy or without nephropathy is confined to Hardy-Weinberg equilibrium. The patients with nephropathy have higher frequency of TGF-beta1 GA/GG genotypes than the patients without nephropathy [GA/GG:AA = 119 (67.6%) : 57 (32.4%) vs. 80 (53.7%) : 69 (46.3%), P < 0.05]. Among patients with diabetic nephropathy, those with TGF-beta1 GA/GG genotypes had higher serum levels of total cholesterol and LDL-cholesterol. CONCLUSION: Our results suggest that TGF-beta1 gene codon 10 polymorphism may contribute to the type 2 diabetic nephropathy.

The Effect of High Glucose and TGF-beta on the Cellular Injury in Cultured Glomerular Epithelial Cells.: Gui Hwa Jeong, Sung Chang Chung, Eui Dal Jung, Yun Jeong Doh, Hee Kyoung Kim, Soon Hong Park, In Hae Park, Jung Guk Kim, Sung Woo Ha, Bo Wan Kim, In Kyu Lee, Cheol Woo Ko; Korean Diabetes J. 2006;30(4):254-263. Published online July 1, 2006; DOI: https://doi.org/10.4093/jkda.2006.30.4.254

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Abstract PDF: BACKGROUND
The glomerulus is a complex physiological structure, as well as selective filtration barrier in the control of renal blood flow and blood pressure. Glomerular epithelial cells may play an important role in development of diabetic nephropathy. Apoptosis of the glomerular epithelial cells are characterized by disappearance of a selective filtration barrier. TGF-beta is a key factor in the development of diabetic nephropathy because of its effects on the accumulation of extracellular matrix and mesangial cell proliferation. We examined whether the high glucose and TGF-beta induce the apoptosis in cultured rat glomerular epithelial cells. METHODS: Glomerular epithelial cells were cultured from rat glomeruli and conditioned with different concentration of TGF-beta or high-glucose. We measured apoptosis of cultured rat glomerular epithelial cell conditioning with different concentration of TGF-beta or high-glucose by using DNA electrophoresis. RESULTS: High glucose (25 mM) induced apoptosis of cultured rat glomerular epithelial cells compared to controls. TGF-beta also induced cell death of cultured rat glomerular epithelial cells in dose dependent manner. CONCLUSION: These results suggest that high glucose and TGF-beta-induced cell death of glomerular epithelial cell may play an important role in diabetic nephropathy and proteinuria. Pathway of apoptosis or cell death by high glucose and TGF-beta must be investigated in the glomerular epithelial cells.

Effect and Mechanism of High Glucose Level on the Expression of an Adhesion Protein, beta ig-h3, and Cellular Function in Endothelial Cells.: Sung Woo Ha, Hye Jin Yeo, Jong Sup Bae, Sung Chang Chung, Jung Guk Kim, In San Kim, In Kyu Lee, Bo Wan Kim; Korean Diabetes J. 2003;27(4):323-331. Published online August 1, 2003

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Abstract PDF: BACKGROUND
Diabetes mellitus is a high risk condition for the development of atherosclerotic and thromboembolic macroangiopathy. There are many factors which are involved in development of these processes. Given the central pathogenic role of endotheliopathy in atherosclerosis, it is likely that this vascular monolayer is the ultimate target of injury in response to many cytokines and growth factors. A dysfunctional endothelium may contribute to the proatherogenic environment. Transforming growth factor (TGF-beta) is a key factor in the development of diabetic angiopathy and atherosclerosis because of its effect on the accumulation of extracellular matrix proteins and endothelial function. The adhesive molecule betaig-h3 is an extracellular matrix protein whose expression is induced by TGF-beta. Considering that TGF-beta plays an important role in diabetic complications and that betaig-h3 is a downstream target gene of TGF-beta, we hypothesized that betaig-h3 may also play a role in the development of diabetic angiopathy through its effect on the endothelial function. Therefore, we examined the effects of high glucose level on the expression of betaig-h3 and endothelial function in human umbilical vein endothelial cells (HUVECs). We also studied the mechanisms of this high glucose-induced betaig-h3 expression. METHODS: Endothelial cells were isolated from human umbilical cord and conditioned with different concentrations of TGF-beta or glucose. We measured TGF-beta and betaig-h3 protein presence/concentration/expression in cell supernatant by ELISA and examined whether TGF-beta is involved in high glucose-induced betaig-h3 expression. Finally, we investigated the biologic function of betaig-h3 in endothelial cells by using adhesion assay. RESULTS: Our study demonstrated that both high glucose level and TGF-beta induced betaig-h3 protein expression in HUVECs. High glucose level also induced TGF-beta protein expression in cells. Anti-TGF-beta antibody almost completely blocked high glucose-induced betaig-h3 expression. betaig-h3 was found to support the adhesion of endothelial cells. CONCLUSION: These results suggest that high glucose level upregulates betaig-h3 protein levels through the induction of TGF-beta and that betaig-h3 may play an important role in diabetic angiopathy by regulating adhesive function of endothelial cells.

Effect of Transforming Growth Factor-Induced Gene Product, beta ig-h3 on Proliferation, Migration, and Adhesion of Aortic Smooth Muscle Cells Cultured in High Glucose.: Sung Woo Ha, Gui Hwa Jung, He Jin Yeo, Jong Sup Bae, Soon Hee Lee, Jung Guk Kim, Rang Woon Park, In San Kim, Bo Wan Kim; Korean Diabetes J. 2002;26(4):286-295. Published online August 1, 2002

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Abstract PDF: BACKGROUND
Diabetes mellitus is associated with a substantial increase in the prevalence of atherosclerotic disease. There are many factors which are involved in development of these processes. Transforming growth factor (TGF-beta) is known to be an important factor in the pathogenesis of diabetic vascular complications. TGF-beta-induced gene-h3 (beta ig-h3) is an adhesive molecule whose expression is induced by TGF-beta. Considering that TGF-beta plays an important role in diabetic complications and that beta ig-h3 is induced by TGF-beta, we hypothesized that beta ig-h3 may also play a role in the development of diabetic angiopathy. Then, we examined the effects of beta ig-h3 on biologic function of vascular smooth muscle cells (VSMCs) and potential roles of beta ig-h3 in the pathognesis of diabetic angiopathy. METHODS: VSMCs were isolated from rat thoracic aorta. We conditioned cells with different concentration of TGF-beta or glucose. We measured TGF-beta and beta ig-h3 protein in cell supernatant by ELISA. We also examined whether TGF-beta involves in high glucose-induced beta ig-h3 expression. Finally, we did proliferation, migration, and adhesion assay to investigate biologic function of beta ig-h3 in VSMCs. RESULTS: Our results demonstrated that TGF-beta induced beta ig-h3 expression in VSMCs in dose dependent manners. High glucose induced TGF expression as well as beta ig-h3 protein. Finally, beta ig-h3 was found to support the proliferation, migration, and adhesion of rat VSMCs. CONCLUSION: These results suggest that high glucose-and TGF-beta-induced beta ig-h3 may play an important role in diabetic angiopathy by regulating proliferation, migration, and adhesion of VSMCs.

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