A comparison of the levels of hepatocyte growth factor in serum in patients with type 1 diabetes mellitus with different stages of diabetic retinopathy

INTRODUCTION: The aim of this study was to evaluate the blood concentration of hepatocyte growth factor (HGF) in patients at various stages of retinopathy. We hypothesised that the high level of HGF found in diabetic patients may be an important marker of retinopathy progression and that HGF level may be an index of the risk of proliferative retinopathy. MATERIAL AND METHODS: The participants in the study were 76 patients with type 1 diabetes mellitus. Of these, 35 patients were without retinopathy and formed Group 1. Of the remaining 41 patients with retinopathy, 20 patients had non-proliferative diabetic retinopathy (NPDR) and formed Group 2, while 21 patients had proliferative diabetic retinopathy (PDR) and formed Group 3. We evaluated the concentration of HGF In the peripheral blood by an enzyme-linked immunosorbent assay. RESULTS: Mean serum concentrations of HGF in the control group were significantly lower than in the type 1 diabetic patients. We found a significant increase in HGF serum concentrations in diabetic patients with PDR compared with the control group. Mean serum HGF concentrations were significantly higher in diabetic subjects with PDR than in diabetic patients without retinopathy. CONCLUSION: HGF concentration is increased in patients with type 1 diabetes mellitus with proliferative retinopathy, and concentrations increase with the progression of retinopathy, suggesting that HGF plays a role in the pathogenesis of proliferative diabetic retinopathy.     

复方血栓通用于早期糖尿病视网膜病变的临床效果及对血清VEGF, IGF-1, NSE水平的影响

目的:研究复方血栓通用于早期糖尿病视网膜病变的临床效果及对血清VEGF、IGF-1、NSE水平的影响。方法:选取2015年7月至2016年7月我院收治的68例早期糖尿病视网膜病变患者为研究对象,按照随机数表法分为复方血栓通组(n=34)和对照组(n=34)。对照组应用常规治疗方法治疗,复方血栓通组在此基础上应用复方血栓通治疗。比较两组患者临床治疗效果、治疗前后出血斑面积、视野灰度值、黄斑厚度以及血管瘤体积情况、血清VEGF、IGF-1、NSE水平的变化情况以及不良反应的发生情况。结果:治疗后,复方血栓通组临床总有效率明显高于对照组,而复发率则显著低于对照组(P0.05)。两组出血斑面积、视野灰度值、黄斑厚度、血管瘤体积以及血清VEGF、IGF-1、NSE水平均较治疗前均明显下降,且与对照组相比,复方血栓通组下降程度更明显(P0.05)。两组均未见明显不良反应发生。结论:复方血栓通可有效降低早期糖尿病视网膜病变患者血清VEGF、IGF-1、NSE水平,减少复发,延缓血管增殖,改善患者视网膜状况,临床疗效显著。     

Regulation of vascular endothelial growth factor-dependent retinal neovascularization by insulin-like growth factor-1 receptor

Although insulin-like growth factor 1 (IGF-1) has been associated with retinopathy, proof of a direct relationship has been lacking. Here we show that an IGF-1 receptor antagonist suppresses retinal neovascularization in vivo, and infer that interactions between IGF-1 and the IGF-1 receptor are necessary for induction of maximal neovascularization by vascular endothelial growth factor (VEGF). IGF-1 receptor regulation of VEGF action is mediated at least in part through control of VEGF activation of p44/42 mitogen-activated protein kinase, establishing a hierarchical relationship between IGF-1 and VEGF receptors. These findings establish an essential role for IGF-1 in angiogenesis and demonstrate a new target for control of retinopathy. They also explain why diabetic retinopathy initially increases with the onset of insulin treatment. IGF-1 levels, low in untreated diabetes, rise with insulin therapy, permitting VEGF-induced retinopathy.     

Insulin, insulin analogues and diabetic retinopathy

Insulin is absolutely vital for living beings. It is not only involved in metabolism, but also in the regulation of growth factors, e.g. IGF-1. In this review we address the role insulin has in the natural evolution of diabetic retinopathy. On the one hand, chronic deficiency of insulin and IGF-1 at the retina is thought to cause capillary degeneration, with subsequent ischaemia. On the other hand, acute abundance of (exogenously administered) insulin and IGF-1 enhances ischaemia-induced VEGF expression. A critical ratio of tissue VEGF-susceptibility: VEGF-availability triggers vascular proliferation (i.e. of micro-aneurysms and/or abnormal vessels). The patent-protected insulin analogues Lispro, Glulisine, Aspart, Glargine and Detemir are artificial insulin derivatives with altered biological responses compared to natural insulin (e.g. divergent insulin and /or IGF-1 receptor-binding characteristics, signalling patterns, and mitogenicity). Their safety profiles concerning diabetic retinopathy remain to be established by randomised controlled trials. Anecdotal reports and circumstantial evidence suggest that Lispro and Glargine might worsen diabetic retinopathy.     

The therapeutic problem of proliferative diabetic retinopathy: targeting somatostatin receptors.

Clinical management of proliferative diabetic retinopathy has changed very little in the last 5 decades, relying primarily on laser ablation of the retinal vasculature. Several lines of clinical and experimental evidence suggest that somatostatin analogues may be efficacious in inhibiting neovascularization associated with proliferative retinopathy but the mechanism of action for these compounds is unclear. Inhibition of growth hormone secretion and the subsequent suppression of insulin-like growth factor 1 (IGF-1) production by somatostatin has been suggested as the mechanism of action, however, in vitro studies suggest that somatostatin analogues suppress endothelial cell growth through a direct, somatostatin receptor-mediated inhibition of pro-survival signaling pathways. The advent of a new generation of modified peptide and peptidomimetic somatostatin analogues has allowed investigators to more carefully define the receptor subtypes responsible for somatostatin-induced endothelial cell death and may eventually lead to the clinical development of somatostatin analogues that can reduce endothelial cell proliferation, independent of suppression of circulating hormone levels.     

Increased levels of vascular endothelial growth factor and advanced glycation end products in aqueous humor of patients with diabetic retinopathy.

Clinical studies have shown a relationship between diabetic retinopathy and vascular endothelial growth factor (VEGF) levels in ocular fluid. Advanced glycation end products (AGEs) have been implicated in diabetes complications, including diabetic retinopathy. Nepsilon-(carboxymethyl) lysine (CML) is a glycoxidation product that may be a marker of oxidative stress. In this study, we used enzyme-linked immunosorbent assays to determine the levels of VEGF, non-CML AGE and CML in the aqueous humor and serum of 82 Japanese patients with type 2 diabetes and 60 non-diabetic subjects. VEGF, non-CML AGE, and CML concentrations in aqueous humor and serum were then compared with the severity of diabetic retinopathy. Immunohistochemical detection analysis of non-CML AGE and CML was also performed using retinal tissues from patients with progressive diabetic retinopathy. Aqueous levels of VEGF, non-CML AGE and CML increased along with the progression of diabetic retinopathy compared to age-matched controls. After coagulation therapy, the VEGF, non-CML AGE, and CML levels were significantly reduced. Immunostaining showed diffuse co-localization of non-CML AGE and CML around microvessels and in the glial cells of proliferative membranes from patients with progressive diabetic retinopathy. These findings suggest that glycation and glycoxidation reactions (or oxidation, as revealed by CML) may contribute to both the onset and progression of diabetic retinopathy.     

Impact of diabetic serum on endothelial cells: an in-vitro-analysis of endothelial dysfunction in diabetes mellitus type 2

Diabetic endothelial dysfunction was characterized by altered levels of adhesion molecules and cytokines. Aim of our study was to evaluate the effects of diabetic serum on cell-growth and proinflammatory markers in human saphenous vein endothelial cells (HSVEC) from diabetic and non-diabetic patients. Diabetic serum showed (1) complementary proliferative activity for non-diabetic and diabetic HSVEC, (2) unchanged surface expression of adhesion molecules, and (3) elevated levels of sICAM-1 in HSVEC of all donors. The concentration of sVCAM-1 was increased only in diabetic cells. The proinflammatory state of diabetic HSVEC characterized by increased levels of cytokines was compensated. We concluded that even under normoglycemic conditions the serum itself contains critical factors leading to abnormal regulation of inflammation in diabetics. We introduced an in vitro model of diabetes representing the endothelial situation at the beginning of diabetes (non-diabetic cells/diabetic serum) as well as the diabetic chronic state (diabetic cells/diabetic serum).     

Retinal blood flow in diabetic retinopathy.

OBJECTIVES--(a) To report on the basic parameters of retinal blood flow in a population of diabetic patients with and without retinopathy and non-diabetic controls; (b) to formulate a haemodynamic model for the pathogenesis of diabetic retinopathy from this and other studies. DESIGN--Laser-Doppler velocimetry and computerised image analysis to determine retinal blood flow in a large cross sectional study. SETTING--Diabetic retinopathy outpatient clinic. SUBJECTS--24 non-diabetic controls and 76 diabetic subjects were studied (63 patients with insulin dependent diabetes, 13 with non-insulin dependent diabetes). Of the diabetic subjects, 12 had no diabetic retinopathy, 27 had background retinopathy, 13 had pre-proliferative retinopathy, 12 had proliferative retinopathy, and 12 had had pan-retinal photocoagulation for proliferative retinopathy. MAIN OUTCOME MEASURES--Retinal blood flow (microliters/min) and conductance (rate of flow per unit of perfusion pressure). RESULTS--In comparison with non-diabetic controls (9.52 microliters/min) and diabetic patients with no diabetic retinopathy (9.12 microliters/min) retinal blood flow was significantly increased in all grades of untreated diabetic retinopathy (background 12.13 microliters/min, pre-proliferative 15.27 microliters/min, proliferative 13.88 microliters/min). There was a significant decrease in flow after pan-retinal photocoagulation in comparison with all the other groups studied (4.48 microliters/min). Conductance of the retinal circulation was higher in the untreated diabetic retinopathy groups. These results were independent of age, sex, type of diabetes, duration of diabetes, glycated haemoglobin concentration, blood glucose concentration, blood pressure, and intraocular pressure. CONCLUSIONS--Retinal blood flow is significantly increased in diabetic retinopathy in comparison with non-diabetic controls and diabetic subjects with no retinopathy. This has implications for controlling hypertension and hyperglycaemia as a strategy in reducing morbidity from diabetic retinopathy.     

Insulin and β-adrenergic Receptors Inhibit Retinal Endothelial Cell Apoptosis Through Independent Pathways

Diabetic retinopathy results from altered insulin receptor signaling. Based on previous studies demonstrating an interaction between β-adrenergic receptors and insulin signaling in hyperglycemic conditions, we hypothesized that β-adrenergic receptor stimulation and insulin stimulation would act synergistically to inhibit one of the hallmarks of diabetic retinopathy, namely retinal endothelial cell apoptosis. To test this hypothesis, human retinal endothelial cells were grown in high glucose (25 mM) medium and treated with a β-1-adrenergic receptor agonist (xamoterol, 10 μM) alone, insulin alone (10 nM) or xamoterol + insulin. We then assessed changes in the levels of insulin receptor, insulin-like growth factor (IGF-1) receptor, and Akt phosphorylation, as well as cleaved caspase 3. Xamoterol alone significantly decreased insulin receptor, IGF-1 receptor and Akt phosphorylation, whereas insulin alone increased insulin receptor, IGF-1 receptor, and Akt phosphorylation. Xamoterol significantly decreased apoptosis of retinal endothelial cells. This data suggests that both β-adrenergic receptors and insulin can inhibit retinal endothelial cell apoptosis in hyperglycemic conditions, but inhibition occurs through independent pathways. These findings have implications for treatments of diabetic retinopathy.     

Quantitative analysis of proteins in the tear fluid of patients with diabetic retinopathy

Diabetic retinopathy is the leading cause of new cases of legal blindness among adults in the developed countries. Approximately 40% of all people with diabetes have diabetic retinopathy and 5% of these have sight-threatening form. As the advanced stage, where there is a high risk for vision loss, can develop without any serious symptoms, sometimes it is hard to detect it. A non invasive method to detect biomarkers characteristic for diabetic retinopathy from the tear fluid was developed. Tear samples from diabetic patients with no retinopathy, non proliferative and proliferative stages of diabetic retinopathy were analyzed and the protein content of each sample was compared to the protein content of tear pool from healthy volunteers. The samples were labeled with iTRAQ fourplex labels and were analyzed with nanoHPLC coupled ESI-MS/MS mass spectrometry. The lipocalin 1, lactotransferrin, lacritin, lysozyme C, lipophilin A and immunoglobulin lambda chain were identified as possible biomarker candidates with significantly higher relative levels in the tear of patients with diabetic retinopathy.     

MiR-18b suppresses high-glucose-induced proliferation in HRECs by targeting IGF-1/IGF1R signaling pathways

MicroRNAs (miRNAs) are important for the proliferation of endothelial cells and have been shown to be involved in diabetic retinopathy (DR). In previous study, we found that miRNAs might play a critical role in hyperglycemia-induced endothelial cell proliferation based on miRNA expression profiling. Here, the roles of microRNA-18b (miR-18b) in the proliferation of human retinal endothelial cells (HRECs) were investigated in an in vitro model of HRECs grown in high glucose. We identified that levels of miR-18b were decreased in high-glucose-induced HRECs, compared with those in cells incubated in normal glucose. However, the reduction of miR-18b up-regulated vascular endothelial growth factor (VEGF) secretion and promoted effects on in vitro proliferation of HRECs. Mechanistically, insulin growth factor-1 (IGF-1) was identified as a target of miR-18b. IGF-1 simulation could antagonize the effect induced by miR-18b up-regulation, promoting cell proliferation and increasing VEGF production. In contrast, the opposite results were observed with silencing IGF-1, which was consistent with the effects of miR-18b overexpression. MiR-18b exerted its function on VEGF synthesis and cell proliferation by suppressing the IGF-1/insulin growth factor-1 receptor (IGF1R) pathway, consequently inhibiting the downstream phosphorylation of Akt, MEK, and ERK. Hence, this may provide a new insight into understanding the mechanism of DR pathogenesis, as well as a potential therapeutic target for proliferative DR.     

妊娠高血压视网膜病变影响因素分析及血管内皮功能检测的临床意义

目的:探讨妊娠高血压视网膜病变的影响因素及血管内皮功能检测的临床意义。方法:前瞻性选取2017年1月~2018年12月期间湖北省妇幼保健院收治的150例妊娠高血压视网膜病变患者作为观察组,根据国际通用的Duker-Elder眼底分期标准分为Ⅰ期组69例,Ⅱ期组57例,Ⅲ期组24例。选取同时期该院收治的妊娠高血压无视网膜病变患者40例为对照组。采用酶联免疫吸附法检测血清胰岛素样生长因子(IGF-1)、内皮素-1(ET-1)水平,采用Pearson相关性分析IGF-1和ET-1水平与病变程度的相关性,采用多因素Logistic回归分析妊娠高血压视网膜病变的影响因素。结果:随着Duker-Elder眼底分期的增加,血清ET-1水平呈不断升高趋势,IGF-1水平呈不断下降趋势(P<0.05)。Pearson相关性分析显示,病变程度与血清IGF-1水平呈负相关,而与ET-1水平呈正相关(P<0.05)。单因素分析结果显示,妊娠高血压视网膜病变的发生与病程、孕周、血压、体质量、蛋白尿、红细胞压积有关(P<0.05),而与年龄无关(P>0.05)。Logistic回归分析结果显示,病程>3W、血压≥160/110 mm Hg、体质量>85kg、蛋白尿为+++、红细胞压积>0.35均是妊娠高血压视网膜病变发生的独立危险因素(P<0.05),而孕周>28W则是其保护因素(P<0.05)。结论:妊娠高血压视网膜病变患者存在IGF-1、ET-1的异常表达,且其表达水平与病变程度息息相关。血压、病程、蛋白尿、体质量、红细胞压积均是妊娠高血压视网膜病变发生的独立危险因素,孕周则是其保护因素。     

Insulin-like growth factor-1 and its binding proteins, IGFBP-1 and IGFBP-3, in adolescents with type-1 diabetes mellitus and microalbuminuria

BACKGROUND/AIMS: Numerous clinical and experimental studies suggest that growth factors may contribute to the development of diabetic microvascular complications. The aim of the study was to test the hypothesis that in adolescents with type-1 diabetes mellitus and microalbuminuria (MA) there are specific disorders of serum insulin-like growth factor-1 (IGF-1) and concentrations of its binding proteins, IGFBP-1 and IGFBP-3, that could be of importance in the pathogenesis of microvascular diabetic complications. METHODS: 25 adolescents with MA, 24 adolescents with diabetes without complications, and 17 controls were examined. There were no differences with regard to age, puberty stage, HbA1c and body mass index between the groups examined. Two of the patients in the first group also had diabetic retinopathy. Serum fasting concentrations of IGF-1 and overnight urine albumin concentrations were measured by radioimmunoassay, IGFBP-1 and IGFBP-3 concentrations by immunoradiometric assay and HbA1c by high-performance liquid chromatography methods. Diabetic patients were examined by an experienced ophthalmologist and neurologist. The data were analyzed using Kruskal-Wallis ANOVA and multiple regression analysis. RESULTS: Significantly lower IGF-1 concentrations were found in adolescents with diabetes and MA compared to diabetic patients without complications and healthy contemporaries. IGFBP-1 concentrations were significantly higher and IGFBP-3 concentrations were statistically lower in diabetic patients with MA than in patients without complications. CONCLUSIONS: The IGF-IGFBP system is deranged in adolescents with type-1 diabetes mellitus and MA. Our results suggest the participation of circulating IGFBP-1 in the origin of diabetic complications. It could be also possible that IGFBP-3 takes part in the protection from them.     

Serum IGF-1 levels correlate negatively to liver damage in diabetic rats

Abstract

Diabetes and insulin resistance frequently cause liver damage. Diabetes also causes reduction in liver and blood IGF-1 levels. We investigated the relation between liver damage and IGF-1 levels in diabetic rats. Fourteen Wistar albino rats were divided into control and diabetic groups. Diabetes was induced by streptozotocin. Rats were sacrificed for biochemical and histologic examinations 2 weeks after streptozotocin injection. Serum and liver IGF-1 levels were decreased, liver malondialdehyde (MDA) levels were increased, glutathione peroxidase (GPx) enzymes activities were decreased and serum alanine aminotransferase (ALT) levels were increased in diabetic group. Microscopic examination of liver revealed that normal tissue organization was disrupted in streptozotocin-induced diabetic rats. There was a strongly positive correlation between blood glucose levels and liver injury, and blood and liver IGF-1 levels. There was a strongly negative correlation between blood IGF-1 levels and hepatic injury. Our results suggest that reduction of blood IGF-1 levels correlates with hepatic injury and circulating IGF-1 levels may have predictive value for determining hepatic damage that results from diabetes. In addition, circulating IGF-1 levels are correlated with glutathione levels and the oxidative stress status of diabetic rat liver.     

Elevated plasma CD105 and vitreous VEGF levels in diabetic retinopathy

Diabetic retinopathy is the leading cause of blindness in the industrialized world. Hyperglycaemia induces retinal hypoxia that upregulates a range of vasoactive factors which may lead to macular oedema and/or angiogenesis and hence potentially sight threatening retinopathy. In this study, we have focused on the association of CD105 and vascular endothelial growth factor (VEGF) with the development and progression of diabetic retinopathy by means of quantifying their expression in the plasma and vitreous of diabetic patients. CD105 levels were quantified in the plasma of 38 type I diabetic patients at various stages of retinopathy and 15 non-diabetic controls. In an additional cohort of 11 patients with advanced proliferative retinopathy and 23 control subjects, CD105 and VEGF were measured in the vitreous. The values were expressed as median (range) and statistical analysis was carried out using the non-parametric Mann-Whitney U test. Plasma CD105 levels were significantly increased in diabetic patients [1.8 (1.1-2.4) ng/ml] compared with non-diabetic controls [0.7 (0.3-1.8) ng/ml] (p<0.01). Plasma CD105 levels were elevated in diabetic patients with all stages of retinopathy, the highest level was observed in background retinopathy [2.3 (2.1-2.5) ng/ml] followed by proliferative retinopathy [2.1 (0.9-2.8) ng/ml] and advanced proliferative retinopathy [1.4 (0.6-1.8) ng/ml]. Vitreous contents of CD105 did not differ between controls and patients with advanced proliferative retinopathy, but vitreous levels of VEGF were elevated by approximately 3-fold in patients with advanced proliferative retinopathy [7.2 (1.90-15.60) ng/ml] compared with the control subjects [1.80 (1.10-2.210)] (p<0.01). These observations indicate that plasma levels of CD105 and vitreous levels of VEGF are associated with diabetic retinopathy, suggesting that CD105 and the angiogenic factor VEGF may play a critical role in the development and progression of diabetic retinopathy. Further studies are required to determine whether circulating CD105 levels could serve as a surrogate marker for early stage retinopathy and for monitoring disease progression.     

Elevated lipid peroxides induced angiogenesis in proliferative diabetic retinopathy

Oxidative stress is associated with causation of diabetic vascular complications. A case–control study was undertaken to evaluate the association of platelet thiobarbituric acid reacting substances (TBARS) with the severity of diabetic retinopathy for the first time. Platelet TBARS levels were estimated using standard protocol. Platelet TBARS levels in the cases with non-proliferative diabetic retinopathy, proliferative diabetic retinopathy, and healthy controls were 0.56 ± 0.09, 0.69 ± 0.11 and 0.41 ± 0.1 nmol/h/10⁸ platelets, respectively. A significant increase in platelet TBARS levels was observed in the cases as compared to controls (p < 0.001). Elevated TBARS levels were observed to significantly increase further during the proliferative stage of the disease (p < 0.01). The increase in platelet TBARS levels, and thereby at retinal level, is associated with angiogenesis in diabetic retinopathy. Supplemental anti-oxidant therapy in diabetic retinopathy may prevent ocular angiogenesis resulting as a consequence of oxidative stress.     

Forearm ischaemia as a test of prostacyclin production: Studies in normal subjects and in patients with diabetes mellitus

Plasma levels of 6-oxo-PGF_1α, the hydrolysis product of prostacyclin, were significantly reduced in men with proliferative diabetic retinopathy, compared with normal controls. Male diabetics with back ground or no retinopathy formed an intermediate group with plasma levels of 6-oxo-PGF lower than controls and higher than patients with proliferative retinopathy. Forearm ischaemia increased plasma levels of 6-oxo-PGF by 30% in normal subjects.The increase occurred during arterial occlusion and was diminished by pretreatment with aspirin. The increase after ischaemia may reflect increased prosta cyclin production. In diabetic patients forearm ischaemia produced an increase in plasma 6-oxo-PGF la similar to that seen in control subjects.     

IGF-1 induction by acylated steryl β-glucosides found in a pre-germinated brown rice diet reduces oxidative stress in streptozotocin-induced diabetes

Background

The pathology of diabetic neuropathy involves oxidative stress on pancreatic β-cells, and is related to decreased levels of Insulin-like growth factor 1 (IGF-1). Acylated steryl β-glucoside (PR-ASG) found in pre-germiated brown rice is a bioactive substance exhibiting properties that enhance activity of homocysteine-thiolactonase (HTase), reducing oxidative stress in diabetic neuropathy. The biological importance of PR-ASG in pancreatic β-cells remains unknown.Here we examined the effects of PR-ASG on IGF-1 and glucose metabolism in β-cells exposed to oxidative stress.

Methodology/Principal Findings

In the present study, a pre-germinated brown rice (PR)-diet was tested in streptozotocin (STZ)-induced diabetic rats. Compared with diabetic rats fed control diets, the PR-diet fed rats showed an improvement of serum metabolic and neurophysiological parameters. In addition, IGF-1 levels were found to be increased in the serum, liver, and pancreas of diabetic rats fed the PR-diet. The increased IGF-1 level in the pancreas led us to hypothesize that PR-ASG is protective for islet β-cells against the extensive injury of advanced or severe diabetes. Thus we examined PR-ASG to determine whether it showed anti-apoptotic, pro-proliferative effects on the insulin-secreting β-cells line, INS-1; and additionally, whether PR-ASG stimulated IGF-1 autocrine secretion/IGF-1-dependent glucose metabolism. We have demonstrated for the first time that PR-ASG increases IGF-1 production and secretion from pancreatic β-cells.

Conclusion/Significance

These findings suggest that PR-ASG may affect pancreatic β-cells through the activation of an IGF-1-dependent mechanism in the diabetic condition. Thus, intake of pre-germinated brown rice may have a beneficial effect in the treatment of diabetes, in particular diabetic neuropathy.