transforming-growth-factor-beta and Diabetic-Neuropathies

The structural changes characterising diabetic microangiopathy, which may be referred to as 'abnormal growth' and 'impaired regeneration', strongly suggest a role for a number of aberrantly expressed growth factors, possibly acting in combination, in the development of these complications. This initial speculation has been supported by the detection of increased concentrations of several growth factors in the target tissues of diabetic long-term complications, and by enhanced expression of these growth factors consequent to the activation of the biochemical pathways linking hyperglycaemia to microvascular changes: the polyol pathway; non-enzymatic glycation of proteins; vasoactive hormones; oxidative stress, and hyperglycaemic pseudohypoxia. As to nephropathy, insulin-like growth factor I (IGF-I) seems to be implicated in the earlier stages of the disease, while transforming growth factor beta (TGF beta) is involved both in the early and later stages, being responsible, at least in part, for extracellular matrix (ECM) accumulation. Vascular endothelial growth factor (VEGF) plays a pivotal role both in non-proliferative and proliferative retinopathy. Finally, deficiency of several neurotrophic factors, namely nerve growth factor (NGF) and IGF-I has been related to the degeneration or impaired regeneration occurring in diabetic neuropathy. Knowledge of the involvement of growth factors in diabetic microangiopathy opens the way to new therapeutic interventions aimed at blocking the deleterious actions of several growth factors.

Topics: Diabetes Mellitus, Type 1; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Endothelial Growth Factors; Growth Substances; Humans; Insulin-Like Growth Factor I; Lymphokines; Transforming Growth Factor beta; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

Vitamin D and rosuvastatin are well-known drugs that mediate beneficial effects in treating type-2 diabetes (T2D) complications; however, their anti-neuropathic potential is debatable. Hence, our study investigates their neurotherapeutic potential and the possible underlying mechanisms using a T2D-associated neuropathy rat model.. Diabetic peripheral neuropathy (DPN) was induced with 8 weeks of administration of a high fat fructose diet followed by a single i.p. injection of streptozotocin (35 mg/kg). Six weeks later, DPN developed and rats were divided into five groups; viz., control, untreated DPN, DPN treated with vitamin D (cholecalciferol, 3500 IU/kg/week), DPN treated with rosuvastatin (10 mg/kg/day), or DPN treated with combination vitamin D and rosuvastatin. We determined their anti-neuropathic effects on small nerves (tail flick test); large nerves (electrophysiological and histological examination); neuronal inflammation (TNF-α and IL-18); apoptosis (caspase-3 activity and Bcl-2); mitochondrial function (NRF-1, TFAM, mtDNA, and ATP); and NICD1, Wnt-10α/β-catenin, and TGF-β/Smad-7 pathways.. Two-month treatment with vitamin D and/or rosuvastatin regenerated neuronal function and architecture and abated neuronal inflammation and apoptosis. This was verified by the inhibition of the neuronal content of TNF-α, IL-18, and caspase-3 activity, while augmenting Bcl-2 content in the sciatic nerve. These treatments inhibited the protein expressions of NICD1, Wnt-10α, β-catenin, and TGF-β; increased the sciatic nerve content of Smad-7; and enhanced mitochondrial biogenesis and function.. Vitamin D and/or rosuvastatin alleviated diabetes-induced neuropathy by suppressing Notch1 and Wnt-10α/β-catenin; modulating TGF-β/Smad-7 signaling pathways; and enhancing mitochondrial function, which lessened neuronal degeneration, demyelination, and fibrosis.

Topics: Animals; Anticholesteremic Agents; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Drug Therapy, Combination; Gene Expression Regulation; Male; NF-E2-Related Factor 1; Rats; Rats, Wistar; Receptor, Notch1; Rosuvastatin Calcium; Transforming Growth Factor beta; Vitamin D; Vitamins; Wnt Proteins

Diabetic nephropathy (DN) remains the leading cause of end-stage renal disease (ESRD), a situation that is in part attributable to the lack of effective treatments. Fluorofenidone is a newly developed reagent with anti-fibrotic activity. While fluorofenidone was previously demonstrated to possess renoprotection from DN pathogenesis in db/db mice, the protective process and its underlying mechanisms have not been well studied. To characterize fluorofenidone-derived renoprotection, we treated 5, 8, or 12-week old db/db mice with daily doses of placebo, fluorofenidone, or losartan until 24 weeks of age; the time at which diabetes and DN were fully developed in placebo-treated animals. In comparison to db/db mice receiving fluorofenidone at 12-weeks old, those treated at 5-weeks had less glomerular expansion and better preservation of renal functions, judged by serum creatinine levels, albumin to creatinine ratio, and urinary albumin excretion (mg/24 hours). These benefits of early treatment were associated with significant reductions of multiple DN-promoting events, such as decreased expression of TGF-β1 and the p22phox subunit of NADPH oxidase as well as downregulated activation of protein kinase C-zeta (ζ), ERK and AKT. This improvement in renoprotection following early interventions is not a unique property of DN pathogenesis, as losartan does not apparently offer the same benefits and is not more renoprotective than fluorofenidone. Additionally, the enhanced renoprotection provided by fluorofenidone did not affect the diabetic process, as it did not alter serum levels of glycated serum proteins, glucose, triglyceride or cholesterol. Collectively, we provide evidence that fluorofenidone offers improved renoprotection at early stages of DN pathogenesis.

Topics: Animals; Blood Glucose; Blood Proteins; Cholesterol; Diabetic Neuropathies; Kidney; Male; Mice; Mitogen-Activated Protein Kinase Kinases; NADPH Oxidases; Protein Kinase C; Proto-Oncogene Proteins c-akt; Pyridones; Transforming Growth Factor beta

The mechanism/s leading to diabetic neuropathy are complex. Transforming growth factor-beta1 (TGF-beta1) has been associated with diabetic nephropathy and retinopathy but not neuropathy. In this study, changes in TGF-beta isoforms were examined in vivo and in vitro. Two groups of animals, streptozotocin diabetic with neuropathy and non-diabetic controls were examined at 4 weeks (n=10/group) and 12 weeks (n=8/group). In diabetic DRG using quantitative real-time PCR (QRT-PCR), TGF-beta1 and TGF-beta2 mRNA, but not TGF-beta3, was increased at 4 and 12 weeks. In sciatic nerve TGF-beta3 mRNA was primarily increased. Immunohistochemistry (DRG) and immunoblotting (sciatic nerve) showed similar differential protein expression. In sciatic nerve TGF-beta formed homo- and hetero-dimers, of which beta(2)/beta(3), beta(1)/beta(1), and beta(1)/beta(3) were significantly increased, while that of the TGF-beta(2)/beta(2) homodimer was decreased, in diabetic compared to non-diabetic rats. In vitro, pretreatment of embryonic DRG with TGF-beta neutralizing antibody prevents the increase in total TGF-beta protein observed with high glucose using immunoblotting. In high glucose conditions, combination with TGF-beta2>beta1 increases the percent of cleaved caspase-3 compared to high glucose alone and TGF-beta neutralizing antibody inhibits this increase. Furthermore, consistent with the findings in diabetic DRG and nerve, TGF-beta isoforms applied directly in vitro reduce neurite outgrowth, and this effect is partially reversed by TGF-beta neutralizing antibody. These findings implicate upregulation of TGF-beta in experimental diabetic peripheral neuropathy and indicate a novel mechanism of cellular injury related to elevated glucose levels. In combination, these findings indicate a potential new target for treatment of diabetic peripheral neuropathy.

Topics: Animals; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Gene Expression Regulation; Male; Protein Isoforms; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transforming Growth Factor beta; Transforming Growth Factor beta1; Transforming Growth Factor beta2; Transforming Growth Factor beta3

The expression of TGF beta-inducible gene h3(beta ig-h3) has been used to assess the biological activity of TGF beta in the kidney. In this study, we investigated whether the urinary concentration of beta ig-h3 is associated with diabetic nephropathy in patients with Type 2 diabetes mellitus. We also evaluated the relationship between the urinary concentration of beta ig-3 and proteinuria and microalbuminuria (AER) in a normal healthy population and in Type 2 diabetes patients.. Four hundred and seventy-nine Type 2 diabetic patients without non-diabetic kidney diseases and 528 healthy control subjects were enrolled. The study subjects were divided into five groups: a non-diabetic healthy control group with normal ACR (n = 443), a non-diabetic healthy control group with microalbuminuria (n = 85), a normoalbuminuric diabetic group (n = 198), a microalbuminuric diabetic group (n = 155) and an overt proteinuria group (n = 126). Urinary levels of beta ig-h3 were measured by enzyme-linked immunosorbent assay.. (i) Urinary excretion of beta ig-h3 was significantly higher in the diabetic groups than in the controls, even in the normoalbuminuric stage (25.02 +/- 8.84 vs. 18.67 +/- 6.56, P = 0.03). In diabetic patients, urinary beta ig-h3 levels increased significantly as diabetic nephropathy advanced (25.02 +/- 8.84 vs. 34.06 +/- 24.55 vs. 169.63 +/- 57.33, P < 0.001). (ii) Proteinuria was found to be significantly correlated with urinary beta ig-h3 (healthy control; r = 0.137, P = 0.019, diabetic patients; r = 0.604, P < 0.001). ACR was also found to be significantly related with urinary beta ig-h3 in diabetic patients (r = 0.383, P = 0.006). (iii) In diabetic patients, urinary beta ig-h3 was significantly related with systolic and diastolic blood pressure (systolic blood pressure: r = 0.436, P = 0.024; diastolic blood pressure, r = 0.365, P = 0.042), total cholesterol and HbA(1c) (cholesterol: r = 0.169, P = 0.03, HbA(1c); r = 0.387, P = 0.044). Logistic regression analyses showed that urinary beta ig-h3 was associated with a significant increase in the risk of microalbuminuria and proteinuria in diabetic patients.. Longitudinal monitoring of urinary beta ig-h3 may improve the likelihood of detecting diabetic nephropathy at an earlier stage and beta ig-h3 could be a sensitive marker of diabetic kidney disease progression.

Topics: Albuminuria; Case-Control Studies; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Enzyme-Linked Immunosorbent Assay; Extracellular Matrix Proteins; Female; Humans; Male; Middle Aged; Proteinuria; Risk Factors; Transforming Growth Factor beta

The present study was conducted to determine whether iridoid total glycoside from Cornus officinalis was effective in regulating expression of transforming growth factor beta 1 (TGF-beta1) and preventing overdeposition of extracellular matrix (ECM) in a diabetes state. An experimental rat model of diabetic nephropathy (DN) was successfully induced by one intraperitoneal injection of streptozotocin at a dose of 60 mg x kg(-1) and maintained for 12 weeks. All rats had free access to standard chow and water. Four groups: normal control, diabetic control, diabetic rats with aminoguanidine treatment and diabetic rats with iridoid total glycoside treatment were used in this experiment. All treatments were administered by intragastric gavage (ig). At the end of the experiment, serum was collected for ELISA determination of TGF-beta1 protein level; renal cortex was dissected for reverse transcription polymerase chain reaction (RT-PCR) analysis of its mRNA expression; and immunohistochemistry was introduced to observe ECM deposition. A significantly higher level of protein and mRNA expression of TGF-beta1, and also overdeposition of fibronectin and laminin was found in diabetic rats. Both iridoid total glycoside and aminoguanidine were effective in decreasing serum protein level and glomerular mRNA expression of TGF-beta1, and in preventing renal overdeposition of fibronectin and laminin. This study suggests that iridoid total glycoside is a beneficial agent for prevention and therapy of DN.

Topics: Animals; Cornus; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Extracellular Matrix; Iridoids; Kidney Glomerulus; Male; Rats; Rats, Sprague-Dawley; Transforming Growth Factor beta; Transforming Growth Factor beta1

Advanced glycation end-products (AGEs) play a critical role in diabetic nephropathy by stimulating extracellular matrix (ECM) synthesis. Connective tissue growth factor (CTGF) is a potent inducer of ECM synthesis and increases in the diabetic kidneys. To determine the critical role of CTGF in AGE-induced ECM accumulation leading to diabetic nephropathy, rats were given AGEs by intravenous injection for 6 weeks. AGE treatment induced a significant renal ECM accumulation, as shown by increases in periodic acid-Schiff-positive materials, fibronectin, and type IV collagen (Col IV) accumulation in glomeruli, and a mild renal dysfunction, as shown by increases in urinary volume and protein content. AGE treatment also caused significant increases in renal CTGF and transforming growth factor (TGF)-beta 1 mRNA and protein expression. Direct exposure of rat mesangial cells to AGEs in vitro significantly induced increases in fibronectin and Col IV production, which could be completely prevented by pretreatment with anti-CTGF antibody. AGE treatment also significantly increased both TGF-beta 1 and CTGF mRNA expression; however, inhibition of TGF-beta 1 mRNA expression by shRNA or neutralization of TGF-beta 1 protein by anti-TGF-beta 1 antibody did not significantly prevent AGE-increased expression of CTGF mRNA and protein. These results suggest that AGE-induced CTGF expression, predominantly through a TGF-beta 1-independent pathway, plays a critical role in renal ECM accumulation leading to diabetic nephropathy.

Topics: Animals; Cattle; Collagen Type IV; Connective Tissue Growth Factor; Diabetic Neuropathies; Extracellular Matrix; Fibronectins; Fibrosis; Glycation End Products, Advanced; Immediate-Early Proteins; In Vitro Techniques; Insulin-Like Growth Factor Binding Proteins; Intercellular Signaling Peptides and Proteins; Kidney; Male; Rats; Rats, Wistar; RNA, Messenger; Serum Albumin; Transforming Growth Factor beta; Transforming Growth Factor beta1

To study the distribution of transforming growth factor-beta (TGF-beta) 1, 2 and 3, and TGF-beta receptor types I and II in diabetic foot ulcers, diabetic skin and normal skin by immunohistochemistry, immunofluorescence and Western blotting. We also compared the TGF-betas with those of chronic venous ulcers.. Skin biopsies were obtained from the leg or the foot of non-diabetic and diabetic subjects, and from the edge of diabetic foot ulcers and chronic venous ulcers. Distribution (by immunofluorescence and immunocytochemistry) of TGF-beta 1, 2 and 3 and TGF-beta receptors (RI and RII) was done by staining 8-microm skin sections using appropriate antibodies. Protein levels of TGF-beta were measured by Western blot analysis.. TGF-beta3 expression was increased in the epithelium at the edge of diabetic foot ulcers, being more intense than diabetic and normal skin (P = 0.03, 0.02, respectively), as was its expression in venous ulcers compared with normal skin. However, TGF-beta1 expression was not increased in diabetic foot ulcers and chronic venous ulcers, and was comparable to diabetic and normal skin. There was also no increase for the receptors in diabetic foot ulcers.. The lack of TGF-beta1 up-regulation in both diabetic foot ulcers and venous ulcers may explain the impaired healing in these chronic wounds, and could represent a general pattern for chronicity.

Topics: Activin Receptors, Type I; Blotting, Western; Diabetic Foot; Diabetic Neuropathies; Female; Foot Ulcer; Humans; Immunohistochemistry; Male; Middle Aged; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Reference Values; Skin; Transforming Growth Factor beta; Transforming Growth Factor beta1; Transforming Growth Factor beta2; Transforming Growth Factor beta3; Varicose Ulcer

1. Plasma concentrations of prorenin were determined in a transgenic animal model of nephropathy induced by overexpression of transforming growth factor (TGF)-beta1 in the juxtaglomerular apparatus. 2. In both female and male mice, plasma concentrations of prorenin were higher in transgenic than in non-transgenic animals. In sexually mature mice, plasma prorenin concentrations were higher in males than in females in both transgenic and non-transgenic animals in accordance with a sexual dimorphism of the plasma concentration of prorenin. 3. The results indicate that TGF-beta1-like androgens increase prorenin secretion in the kidneys and may explain the increased plasma prorenin concentrations in patients with diabetic nephropathy.

Topics: Aging; Animals; Diabetic Neuropathies; Disease Models, Animal; Enzyme Precursors; Female; Juxtaglomerular Apparatus; Male; Mice; Mice, Inbred BALB C; Mice, Transgenic; Renin; Transforming Growth Factor beta; Transforming Growth Factor beta1

Transforming growth factor-beta 1 (TGF-beta 1) is a primary determinant of the mesangial expansion observed in diabetic nephropathy. In this study, we quantitated the levels of intraglomerular TGF-beta 1 mRNA in patients with diabetes mellitus using a competitive polymerase chain reaction (PCR) method. Renal biopsy specimens were obtained from 29 patients with non-insulin-dependent diabetes mellitus. Total RNA was extracted from the glomeruli and reverse transcribed into cDNA with reverse transcriptase. To prepare samples containing identical amounts of beta-actin cDNA (8 pg), we performed competitive PCR by co-amplifying mutant templates of beta-actin with a unique EcoRI site. We also used this competitive PCR method to measure TGF-beta 1 cDNA by co-amplifying mutant templates of TGF-beta 1. We observed higher expression of TGF-beta 1 mRNA in glomeruli of patients with diabetic nephropathy as compared with normal glomeruli. Intraglomerular TGF-beta 1 mRNA was elevated, even in the early stage of diabetic nephropathy. Moreover, levels of intraglomerular TGF-beta 1 mRNA correlated with values of HbA1c. These data suggest that hyperglycemia induces intraglomerular TGF-beta 1 mRNA expression in vivo, and that TGF-beta 1 overproduction may be associated with the progression of diabetic nephropathy.

Topics: Aged; Base Sequence; Biopsy; Blotting, Southern; Collagen; Diabetes Mellitus; Diabetic Neuropathies; Female; Humans; Immunohistochemistry; Kidney Glomerulus; Male; Microscopy, Confocal; Middle Aged; Molecular Sequence Data; Polymerase Chain Reaction; RNA, Messenger; Transforming Growth Factor beta

Transforming growth factor-beta (TGF-beta) is a potent inducer of extracellular matrix production and of fibrogenesis and has been associated with the occurrence of diabetic micro- and macrovascular complications. Our aim was to determine whether circulating levels of TGF-beta 1 are altered in NIDDM and, if so, whether they are correlated with blood glucose and show an association with diabetic complications.. Plasma levels of TGF-beta 1 were determined by enzyme-linked immunosorbent assay in 44 NIDDM patients and 28 control subjects of comparable age and weight and were correlated with parameters of metabolic control and the occurrence of micro- and macrovascular complications.. TGF-beta 1 was significantly elevated in NIDDM (7.9 +/- 1.0 ng/ml), as compared with control subjects (3.1 +/- 0.4 ng/ml, P < 0.001) and correlated with glycosylated hemoglobin (r2 = 0.42; P < 0.001). Thrombocyte levels of TGF-beta 1 were similar in control subjects (54 +/- 7 pg/ml, n = 16) and diabetic patients (61.6 +/- 18 pg/ml, n = 13; P = 0.357). Elevated TGF-beta 1 levels were associated with retinopathy and neuropathy.. We conclude that plasma levels of TGF-beta 1 are elevated in NIDDM patients and may be related to average blood glucose. Preliminary data suggest that they may contribute to the occurrence of diabetic complications.

Topics: Aged; Biomarkers; Blood Glucose; Coronary Disease; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Female; Glycated Hemoglobin; Humans; Hypertension; Male; Middle Aged; Reference Values; Regression Analysis; Statistics, Nonparametric; Transforming Growth Factor beta