Adiponectin may play a part in the pathogenesis of diabetic retinopathy

OBJECTIVES: To measure plasma adiponectin concentrations in patients with type 2 diabetes and to investigate any association with the severity of diabetic retinopathy, because adiponectin seems to be an important modulator for metabolic and vascular diseases. METHODS: Seventy-four patients (mean age 46.8+/-5.1 years; body mass index (BMI), 26.8+/-2.10 kg/m(2)) and 54 healthy volunteers (mean age 46.8+/-5.4 years; BMI 26.47+/-2.33 kg/m(2)) were included. RESULTS: Adiponectin concentrations in the patients were significantly lower than those in controls (4.71+/-2.11 microg/ml for patients, n=74; 15.95+/-3.72 microg/ml for controls, n=54; P<0.001). In the patients group there was a significant negative correlation between adiponectin and homeostasis model assessment index (r=-0.318, P=0.006 respectively). Plasma adiponectin concentrations in patients with proliferative diabetic retinopathy (n=20; 3.16+/-1.83 microg/ml) or non-proliferative diabetic retinopathy (n=24; 3.97+/-1.47 microg/ml, P=0.014) were significantly lower than those in patients without diabetic retinopathy (n=30; 6.30+/-1.57 microg/ml, P=0.001). When the presence of diabetes was defined as the final variable in the conditional logistic regression model with the adiponectin concentration as the continuous variable, adiponectin was significantly involved in the model. CONCLUSION: The results show that adiponectin concentrations are lower in patients with type 2 diabetes and that the concentrations are associated with the severity of diabetic retinopathy. Our findings suggest that adiponectin may take part in the pathogenesis of diabetic retinopathy.     

Aqueous levels of macrophage migration inhibitory factor and monocyte chemotactic protein-1 in patients with diabetic retinopathy.

AIMS: To investigate the relationship of aqueous macrophage migration inhibitory factor (MIF) and monocyte chemotactic protein-1 (MCP-1) levels with the clinical stage of diabetic retinopathy. METHODS: We assayed MIF and MCP-1 levels in aqueous humour samples obtained from 40 diabetic patients (49 eyes) and 24 non-diabetic patients (31 eyes) using enzyme-linked immunosorbent assay. According to the clinical stage of diabetic retinopathy, the diabetic patients were classified into non-diabetic retinopathy (11 eyes), non-proliferative diabetic retinopathy (14 eyes) and proliferative diabetic retinopathy (24 eyes). RESULTS: The aqueous levels of MIF (mean +/- sd) were 6.34 +/- 4.53 ng/ml in proliferative diabetic retinopathy, 3.22 +/- 1.71 ng/ml in non proliferative diabetic retinopathy, 1.25 +/- 0.96 ng/ml in non-diabetic retinopathy and 1.07 +/- 0.94 ng/ml in non-diabetic patients. Significant differences were found among these four groups (P < 0.0001). Aqueous MCP-1 levels were 1668.6 +/- 1442.3 pg/ml in proliferative diabetic retinopathy, 1528.6 +/- 1994.6 pg/ml in non-proliferative diabetic retinopathy, 690.2 +/- 402.1 pg/ml in non-diabetic retinopathy and 622.7 +/- 245.3 pg/ml in non-diabetic patients. Significant differences were also found among these four groups (P < 0.0001). After correcting for total aqueous protein, the ratios of MIF and MCP-1 to total protein remained significantly correlated with the clinical stage of diabetic retinopathy (P < 0.0001, P = 0.0004, respectively). The ratios of MIF to total protein significantly correlated with the ratios of MCP-1 to total protein in diabetic patients (r = 0.680, P < 0.0001). CONCLUSIONS: Aqueous MIF levels significantly correlated with aqueous MCP-1 levels and the clinical stage of diabetic retinopathy. The results suggest that MIF has a co-operative role with MCP-1 in the progression of diabetic retinopathy.     

Plasma adiponectin and serum advanced glycated end-products increase and plasma lipid concentrations decrease with increasing duration of type 2 diabetes

OBJECTIVE: To prospectively follow the concentrations of plasma adiponectin (p-adiponectin) and serum advanced glycation end-products (s-AGE) in relation to plasma lipids and retinopathy over 3 years in type 2 diabetic patients. DESIGN AND METHODS: P-adiponectin, s-AGE, plasma lipids and diabetic retinopathy were prospectively evaluated in 61 type 2 diabetic patients at baseline and at follow up 3 years later. RESULTS: Mean p-adiponectin (from 8.84+/-5.14 to 11.05+/-6.16 microg/ml; P=0.006) and s-AGE (from 637+/-242 to 781+/-173 ng/ml; P<0.0001) concentrations had increased at follow up. In addition, HbA1c (7.7+/-1.7 to 7.4+/-1.4%; P=0.0045) and fasting C-peptide (1.00+/-0.38 to 0.81+/-0.35 nM; P=0.019) had decreased and all lipid variables had significantly improved at follow up. P-adiponectin correlated inversely with fasting C-peptide (r(s)=-0.273; P=0.045) and low-density lipoprotein (LDL)/high-density lipoprotein (HDL) ratio (r(s)=-0.362; P=0.011), and directly with plasma HDL cholesterol (r(s)=0.381; P=0.005) at follow up. Analysis of variance with adiponectin and s-AGE as dependent variables and fasting C-peptide, plasma HDL and plasma LDL cholesterol as covariates demonstrated that the increase in s-AGE was independent (P=0.001) and the increase in p-adiponectin dependent on covariate changes (P=0.862). There was a slight correlation between s-AGE at baseline versus the degree of retinopathy at follow up (r(s)=0.281; P=0.0499). CONCLUSION: Both p-adiponectin and s-AGE increased during the 3 years. The increase in p-adiponectin was explained by improvements in insulin sensitivity and dyslipidaemia, whereas the increase in s-AGE was independent of changes in metabolic covariates. s-AGE increase when the duration of type 2 diabetes increases.     

Biochemical markers of type III and I collagen: association with retinopathy and neuropathy in type 1 diabetic subjects.

AIMS: Connective tissue alterations may contribute to the development of diabetic long-term complications in eyes, kidneys and peripheral nerves. Collagen deposition may be increased in micro- and macrovascular disease in diabetic subjects. We tested whether biochemical markers of type III and I collagen metabolism are associated with retinopathy and neuropathy in Type 1 diabetes. METHODS: A total of 28 patients, mean age 43.4 +/- 9.5 (sd) and duration of diabetes 25.2 +/- 9.7 years, were studied. Stereoscopic colour fundus photographs were taken for assessment of retinopathy which was classified as no, background or proliferative. Concentrations of aminoterminal propeptide of type III procollagen (PIIINP), carboxyterminal propeptide of type I procollagen (PICP) and carboxyterminal cross-linked telopeptide of type I collagen (ICTP) in serum and urinary excretion of cross-linked N-telopeptides of type I collagen (NTX) and deoxypyridinoline crosslinks (DPyr) into urine were measured. RESULTS: Average serum PIIINP was higher in subjects with proliferative (3.2 +/- 1.1 microg/l) than without proliferative retinopathy (2.5 +/- 0.6 microg/l) (P = 0.03). Average serum PICP was higher in subjects without retinopathy (181.7 +/- 19.5 microg/l) than in subjects with background retinopathy (132.1 +/- 42.7 microg/l) (P = 0.02). Concentrations of other collagen markers were not different in subjects with or without retinopathy. No association between collagen markers and neuropathy was found. CONCLUSIONS: The increased synthesis of type III collagen, reflecting deposition of matrix and basement membrane connective tissue, may be involved in the pathogenesis of proliferative retinopathy in Type 1 diabetic subjects. On the other hand, we observed decreased synthesis of Type I collagen, which can result in weakened vascular integrity in subjects with retinopathy.     

Increased levels of platelet-derived microparticles in patients with diabetic retinopathy

Diabetic retinopathy is caused by capillary occlusions. Platelet-derived microparticles (PMPs) stimulate the coagulation cascade and increase leukocyte and endothelial cell adhesions, both of which are key events in the development of diabetic retinopathy. However, the correlation between the levels of PMPs and diabetic retinopathy has not been precisely determined. The PMPs levels and the expression of platelet CD62P and CD63 were measured in 92 diabetic patients. The level of PMPs was significantly correlated with the expression of CD62P (r = 0.76, P < 0.0001) and CD63 (r = 0.71, P < 0.0001). The mean level of PMPs in diabetics (507+/-15/10(4) platelets (plt), mean+/-S.E.) was significantly higher than that in normal. The PMPs levels increased with the progression of the diabetic retinopathy; 480+/-28/10(4) plt in diabetic patients without retinopathy (n = 25), 504+/-40/10(4) plt with mild or moderate non-proliferative diabetic retinopathy (n = 13), 512+/-29/10(4) plt with severe non-proliferative diabetic retinopathy (n = 25), and 528+/-25/10(4) plt with proliferative diabetic retinopathy (n=29). The PMPs level in patients with non-perfused retinal areas (582+/-27/10(4) plt, n = 24) was significantly higher than patients without non-perfused areas (469+/-23/10(4) plt, n = 30; P = 0.0096) and without diabetic retinopathy (P = 0.024). These high correlations indicate that increased levels of PMPs may accelerate diabetic retinopathy.     

Elevation of monocyte-derived microparticles in patients with diabetic retinopathy

Diabetic retinopathy is associated with microvascular damage and capillary occlusions which are common features of the microangiopathy in diabetes. Monocyte-derived microparticles (MDMPs) are released from activated monocytes and enhance the procoagulant activity, and also activate adhesion reactions. These are key events in the development of capillary occlusion. The MDMPs level in the blood, and platelet activation markers (platelet-derived microparticles (PDMPs), CD62P and CD63) were measured by flow cytometry in 72 diabetic patients. The plasma levels of intracellular adhesion molecule-1 (ICAM-1) and P-selectin were analyzed by ELISA. The level of MDMPs was significantly correlated with the levels of PDMPs (r=0.52, P<0.001), CD62P (r=0.37, P=0.001), CD63 (r=0.31 and P=0.007), P-selectin (r=0.38, P=0.001), and ICAM-1 (r=0.31, P=0.009). The MDMPs level increased with the progression of the diabetic retinopathy: 81+/-14/10(4)platelets (plts) in patients without retinopathy (n=10); 88+/-8/10(4)plts with mild or moderate non-proliferative diabetic retinopathy (NPDR, n=12); 95+/-8/10(4)plts with severe NPDR (n=24); and 112+/-9/10(4)plts with proliferative diabetic retinopathy (PDR) (n=26). The MDMPs level in patients with areas of capillary occlusion (123+/-10/10(4)plts, n=25) was significantly higher than that in patients without areas of capillary occlusion (84+/-5/10(4)plts, n=25; P=0.0008). These correlations suggest that increased levels of MDMPs may accelerate the progression of diabetic retinopathy.     

Plasma thrombomodulin concentration in diabetes mellitus

Thrombomodulin is an endothelial cell membrane protein acting as a cofactor for the activation of plasma protein C. Recently, it was found that soluble forms of thrombomodulin exist in plasma. Although the physiological significance of circulating thrombomodulin is presently obscure, it may reflect injury of the endothelial cell. In the present study, we examined plasma thrombomodulin concentrations in 106 Type 2 (non-insulin-dependent) diabetic patients. Plasma thrombomodulin was determined by a sandwich ELISA employing monoclonal anti-thrombomodulin antibodies. The patients with proteinuria had higher plasma thrombomodulin concentrations (61.0 +/- 36.0 ng/ml) compared to the patients without proteinuria (33.6 +/- 9.5 ng/ml, P less than 0.001) and control subjects (32.8 +/- 6.5 ng/ml, P less than 0.001). Plasma thrombomodulin concentrations were positively correlated with the level of serum creatine, blood urea nitrogen, urinary albumin and urinary beta 2-microglobulin (P less than 0.001 for each), but not with fasting plasma glucose, hemoglobin A1c or fructosamine. Elevated plasma thrombomodulin was also observed in the patients with pre-proliferative (63.4 +/- 28.9 ng/ml) or proliferative retinopathy (57.4 +/- 34.7 ng/ml), but not in the patients with non-proliferative retinopathy (33.5 +/- 12.9 ng/ml) or those without retinopathy (32.4 +/- 8.9 ng/ml). Even in the 81 diabetic subjects without proteinuria as determined by a dip and read method, and whose serum creatinine was lower than 1.0 mg/dl, the plasma thrombomodulin concentration was significantly higher in the patients with pre-proliferative (41.5 +/- 4.4 ng/ml) and proliferative retinopathy (41.0 +/- 12.8 ng/ml) compared to the patients without retinopathy (32.2 +/- 8.8 ng/ml) and those with non-proliferative retinopathy (31.9 +/- 7.8 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

The relationship between self-monitoring of blood glucose control and glycosylated haemoglobin in patients with type 2 diabetes with and without diabetic retinopathy

BACKGROUND: Diabetes mellitus (DM) is a major health problem with long-term microvascular and macrovascular complications responsible for the majority of its mortality and morbidity. The development and progression of diabetic complications are strongly related to the degree of glycemic control. To decrease the occurrence of these complications, instruments for self-monitoring of blood glucose (SMBG) have been developed and have become widely used among diabetic patients. In this study, we determined the relationship between SMBG control and glycosylated haemoglobin (HbA(lc)) levels in patients with type 2 diabetes, with and without diabetic retinopathy. METHODS: Two hundred and sixty-seven type 2 diabetic patients (mean age [mean+/-S.D.]: 58.07+/-9.13 years, duration of diabetes: 8.63+/-6.8 years) participated in this study. Following an educational program on SMBG, glucometers and usage of oral antidiabetic agents or insulin, optic fundi were examined and HbA(lc) levels were measured at baseline and after 6 and 12 months. The patients were classified in three groups according to their funduscopic findings: without retinopathy (n=140, 52.4%), background retinopathy (n=75, 28.1%) and proliferative retinopathy (n=52, 19.5%). RESULTS: HbA(lc) levels at baseline, after 6 and 12 months were 9.09+/-2.69%, 7.47+/-1.78% and 7.12+/-1.4%, respectively, mean+/-S.D. The values decreased significantly after the education program (P<.001 for both values compared with baseline). The prevalence of retinopathy (both background and proliferative) was 0.8% in the group of diabetics with a mean HbA(lc) level <6%, 7.1% in those between 6.1% and 6.9%; 9.4% in those between 7% and 7.9%; 11.8% between 8% and 8.9%; and 70.9% in those exceeding a mean HbA(lc) level of 9%. There was a statically significant relationship between proliferative diabetic retinopathy and body mass index (BMI; P<.001). The same relationship was observed between duration of diabetes and diabetic retinopathy (P<.001), but not between sex and diabetic retinopathy (P=.46). CONCLUSIONS: Implementing a program of SMBG control in type 2 diabetic patients results in lower levels of HbA(lc) at 6 and 12 months. In the group without diabetic retinopathy at 6- and 12-month controls, the mean HbA(lc) concentration is less than 7%, but in the group with diabetic (background and proliferative) retinopathy, this value could not be reduced below 7%. These results imply that SMBG would allow us to maintain better metabolic control by improving HbA(lc) levels and we have always kept in mind that SMBG was a part of an educational program. On the other hand, improving glycemic control prevents the onset or progression of diabetic microvascular complications, such as diabetic retinopathy, nephropathy and neuropathy. Long-term clinical studies should be performed to determine cost-effectiveness and the effects of SMBG on diabetic complications, morbidity and mortality.     

Increased serum pigment epithelium-derived factor is associated with microvascular complications, vascular stiffness and inflammation in Type 1 diabetes.

AIMS: To determine in Type 1 diabetes patients if levels of pigment epithelium-derived factor (PEDF), an anti-angiogenic, anti-inflammatory and antioxidant factor, are increased in individuals with complications and positively related to vascular and renal dysfunction, body mass index, glycated haemoglobin, lipids, inflammation and oxidative stress. METHODS: Serum PEDF levels were measured by ELISA in a cross-sectional study of 123 Type 1 diabetic patients (71 without and 52 with microvascular complications) and 31 non-diabetic control subjects. PEDF associations with complication status, pulse-wave analysis and biochemical results were explored. RESULTS: PEDF levels [geometric mean (95% CI)] were increased in patients with complications 8.2 (7.0-9.6) microg/ml, vs. complication-free patients [5.3 (4.7-6.0) microg/ml, P < 0.001] and control subjects [5.3 (4.6-6.1) microg/ml, P < 0.001; anova between three groups, P < 0.001], but did not differ significantly between control subjects and complication-free patients (P > 0.05). In diabetes, PEDF levels correlated (all P < 0.001) with systolic blood pressure (r = 0.317), pulse pressure (r = 0.337), small artery elasticity (r = -0.269), glycated haemoglobin (r = 0.245), body mass index (r = 0.362), renal dysfunction [including serum creatinine (r = 0.491), cystatin C (r = 0.500)], triglycerides (r = 0.367), and inflammation [including log(e)C-reactive protein (CRP; r = 0.329), and soluble vascular cell adhesion molecule-1 (r = 0.363)]. Age, blood urea nitrogen, systolic blood pressure, pulse pressure and log(e)CRP correlated with PEDF levels in control subjects (all P < 0.04). PEDF levels were not significantly correlated with measures of oxidative stress: isoprostanes, oxidized low-density lipoprotein or paraoxonase-1 activity. On stepwise linear regression analysis (all subjects), independent determinants of PEDF levels were renal function, triglycerides, inflammation, small artery elasticity and age (r(2) = 0.427). CONCLUSIONS: In Type 1 diabetes, serum PEDF levels are associated with microvascular complications, poor vascular health, hyperglycaemia, adiposity and inflammation.     

Elevated serum levels of pigment epithelium-derived factor in the metabolic syndrome

CONTEXT: Pigment epithelium-derived factor (PEDF), a potent inhibitor of angiogenesis with neuronal differentiating activity, inhibits endothelial cell injury in vitro, thus suggesting the involvement of PEDF in atherosclerosis. Therefore, elucidating the relationship between serum levels of PEDF and coronary risk factors could provide a clue to understanding the pathophysiological role of PEDF in vivo. OBJECTIVE: We examined whether serum levels of PEDF were associated with risk factors for coronary artery disease. DESIGN: The study was designed as a cross-sectional study. Setting: The study was set within the general community. PATIENTS OR OTHER PARTICIPANTS: A total of 196 general Japanese residents (age 65.7 +/- 9.3 yr; 71 males and 125 females) without clinical evidence of coronary or peripheral arterial occlusive diseases were enrolled in this study. RESULTS: PEDF showed a normal distribution, ranging from 8-24 microg/ml, with a mean of 14.6 +/- 3.2 microg/ml. Multivariate analyses revealed that uric acid (P < 0.001), waist circumference (P = 0.009), insulin (P = 0.019), and triglycerides (P = 0.028) were significant independent determinants of serum PEDF levels. Age- and uric acid-adjusted PEDF levels were significantly higher (P = 0.048 for men and P = 0.007 for women) in proportion to the accumulation of the number of the components of the metabolic syndrome. CONCLUSIONS: The present study reveals that serum levels of PEDF are strongly associated with the metabolic syndrome. Our results suggest that serum PEDF levels may be elevated as a counter-system in the metabolic syndrome.     

The association of plasma adiponectin levels with hypertensive retinopathy

OBJECTIVE: Previous studies have demonstrated that low plasma adiponectin concentrations are associated with essential hypertension. It has also recently been shown that adiponectin plays an essential role in the modulation of angiogenesis. These data led us to hypothesize that adiponectin might contribute to end-organ damage in hypertension. METHODS: In the present study we have evaluated the relationship between plasma adiponectin concentrations and hypertensive retinopathy. One hundred and ten patients newly diagnosed with essential hypertension (EHT) (mean age, 46.79+/-5.0 years; body mass index (BMI), 26.47+/-2.23 kg/m(2); male/female ratio, 58/52) and 57 healthy normotensive control subjects (NT) (mean age, 46.84+/-5.4 years; BMI, 26.66+/-2.65 kg/m(2); male/female ratio, 33/24) were enrolled. RESULTS: Plasma adiponectin levels were significantly lower in EHT than in NT (P < 0.001). In addition, adiponectin concentrations were strongly correlated with systolic and diastolic blood pressures in EHT (r = -0.757, P < 0.001; r = -0.761, P < 0.001) while there was no correlation in the NT group. Plasma adiponectin in patients with grade 0 hypertensive retinopathy (n = 52) was significantly higher than that of the patients with grade 1 (n = 30) and 2 (n = 28) hypertensive retinopathy (P < 0.001 for each). Plasma adiponectin in patients with grade 0 hypertensive retinopathy was also significantly lower than that in the NT group (P < 0.001). The estimated threshold of plasma adiponectin concentration for hypertensive retinopathy was 17 microg/ml. This critical adiponectin level served largely to separate patients with retinopathy from those without. CONCLUSION: Our results have shown that plasma adiponectin concentrations decrease progressively with higher grades of hypertensive retinopathy even after correction for other atherogenic risk factors, suggesting that a critical adiponectin level is needed for the development of retinopathy.     

血浆同型半胱氨酸浓度与2型糖尿病视网膜病变的关系

目的　观察空腹血浆总同型半胱氨酸 (Hcy)水平与 2型糖尿病视网膜病变发生发展的关系。方法　研究对象为 5 5例 2型糖尿病 (DM)和 19例 (男 12例 ,女 7例 )非DM健康对照者 (CON)。DM组分为两个亚组 :无微血管并发症 (NDC)组 39例 (男 17例 ,女 2 2例 ) ,糖尿病视网膜病变 (DR)组16例 (男 8例 ,女 8例 )。所有患者肾功能和尿白蛋白 /肌酐 (Alb/Cr)均正常。根据眼底荧光造影判断视网膜病变的严重程度。应用高效液相 反相色谱分析和荧光检测的方法测定空腹血浆总Hcy水平。结果　DR组、NDC组和CON组间的血浆总Hcy浓度差异有显著性 (F =2 4 0 5 ,P =0 0 31) ,DR组血浆总Hcy水平 [(14 7± 5 2 8) μmol/L]显著高于NDC组 [(11 3± 4 94) μmol/L]和CON组 [(9 6 5± 2 6 6 )μmol/L]。NDC组与CON组比较差异无显著性。在DR组 ,增殖性视网膜病变 (PDR)亚组总Hcy水平显著高于背景性视网膜病变 (BDR)亚组 (t=2 4 0 5 ,P =0 0 31)。本研究中 ,总Hcy超过 14 97μmol/L即为高同型半胱氨酸血症 ,其中PDR亚组有 4例 ,BDR亚组为 1例。结论　伴视网膜病变的 2型DM患者血浆总Hcy水平高于正常人 ,其中PDR组的血浆总Hcy浓度高于BDR组。空腹血浆同型半胱氨酸水平可能是 2型糖尿病视网膜病变的重要危险因素之一。     

Inverse correlation between activated protein C generation and carotid atherosclerosis in Type 2 diabetic patients.

AIMS: Activated protein C (APC) is a key regulator of the clotting system and immune responses. We studied the relationship between the degree of atherosclerosis as measured by the intima-media thickness (IMT) of carotid artery and APC generation in Type 2 diabetic patients. METHODS: Eighty-seven Type 2 diabetic patients and 35 control subjects participated. APC generation was assessed by the plasma APC-protein C inhibitor complex (APC-PCI) levels and the mean IMT of carotid artery was measured by ultrasonography. The plasma levels of the thrombin-anti-thromobin complex (TAT) and platelet-derived growth factor (PDGF) were measured by enzyme-linked immunoassays. RESULTS: Plasma TAT levels were significantly higher in diabetic patients [2.03 (1.12, 2.56) ng/ml, median (25th, 75th percentile)] compared with control subjects [0.85 (0.55, 2.08) ng/ml, P < 0.01]. Plasma APC-PCI levels were significantly lower in diabetic patients [0.93 (0.74, 1.22) ng/ml], than in control subjects [1.66 (1.25, 2.36) ng/ml, P < 0.001]. The mean IMT was significantly increased in diabetic patients (0.881 +/- 0.242 mm; mean +/- sd) compared with control subjects (0.669 +/- 0.140 mm; P < 0.01). Univariate analysis showed a significant and inverse correlation between plasma APC-PCI levels and mean IMT (r = -0.32, P < 0.005), and multivariate regression analysis confirmed the independent correlation (P < 0.05). Moreover, plasma APC-PCI levels significantly and inversely correlated with plasma PDGF levels in diabetic patients (r = -0.30, P < 0.01). CONCLUSIONS: These results suggest that decreased APC generation is associated with vascular atherosclerotic changes in Type 2 diabetic patients.     

Plasma thrombin-activatable fibrinolysis inhibitor and plasminogen activator inhibitor-1 levels in inflammatory bowel disease

BACKGROUND: Patients with inflammatory bowel disease (IBD) have an increased risk of thromboembolic events. Imbalance of fibrinolysis has been suggested as one of the possible pathogenetic mechanisms. As plasminogen activator inhibitor-1 (PAI-1) and thrombin-activatable fibrinolysis inhibitor (TAFI) are inhibitors of fibrinolysis, we studied TAFI as well as PAI-1 plasma levels in IBD patients compared with healthy controls. METHODS: A total of 132 IBD patients [68 ulcerative colitis (UC) and 64 Crohn's disease (CD)] and 50 healthy controls were enrolled. PAI-1 and TAFI plasma levels were assessed by commercially available enzyme-linked immunosorbent assay kits. Their relationship with clinical parameters of UC and CD was assessed. RESULTS: Mean plasma PAI-1 levels were significantly higher in both UC patients (3.9+/-1.3 IU/ml) and CD patients (4.0+/-1.5 IU/ml) compared with healthy controls (3.1+/-1.1 IU/ml) (P=0.01). On the other hand, mean plasma TAFI levels were significantly lower in both UC patients (14.7+/-3.1 microg/ml) and CD patients (13.3+/-3.4 microg/ml) compared with healthy controls (17.4+/-3.0 microg/ml) (P<0.0001). Patients with active disease had significantly higher PAI-1 levels compared with patients with inactive disease for both diseases (P=0.03 and P=0.01, respectively). No significant association between plasma TAFI levels and disease activity was also found. Plasma TAFI levels were significantly lower in patients with ileal CD compared with patients with colonic CD. CONCLUSION: PAI-1 plasma levels are increased whereas TAFI levels are decreased in IBD patients. These results suggest an imbalance of fibrinolysis in IBD.     

Deficient activation and different expression of transforming growth factor-beta isoforms in active proliferative diabetic retinopathy and neovascular eye disease.

An increased expression and secretion of angiogenic growth factors was proposed to occur in proliferative diabetic retinopathy and other neovascularizing retinal diseases. However, a loss of anti-angiogenic factors also might promote retinal neovascularization. Therefore we investigated the active and latent vitreous levels of the subtypes of the endothelial anti-mitogen transforming growth factor-beta in vitreous of 58 patients. Four groups of patients were compared: Controls without retinal hypoxia, patients with quiescent and active proliferative diabetic retinopathy (PDR), and patients with severe retinal hypoxia resulting in rubeosis iridis. Whereas the amount of total TGF-beta in the four groups did not differ significantly, latent TGF-beta isoform expression showed complex alterations in ocular vitreous. Levels of active TGF-beta of patients with active PDR (79.5 +/- 28 pg/ml; n = 8) were decreased to 20% of the control levels (378 +/- 55 pg/ml; n = 12; p = 0.0005) and 25% of the mean concentration in quiescent PDR (346 +/- 64 pg/ml; n = 9; p = 0.0021). Levels in rubeosis (52 +/- 10 pg/ml; n = 10) did not differ significantly from those found in active PDR but were decreased to 15% of those in patients with quiescent PDR (p = 0.0004). Furthermore a highly significant inverse correlation between active TGF-beta and alpha2-antiplasmin, a liver produced inhibitor of the activation of TGF-beta by plasmin was noted (r = -0.59; n = 28; p = 0.001). We conclude that deficient activation of TGF-beta occurs in active proliferative diabetic retinopathy and in hypoxic angiogenesis most likely as a consequence of a blood retina barrier breakdown and influx of alpha2-antiplasmin from serum. The disinhibition of endothelial cell proliferation may be a central component in the process of neovascularization.     

Inflammatory cytokines in vitreous fluid and serum of patients with diabetic vitreoretinopathy

To determine whether inflammatory cytokines are increased in proliferative diabetic retinopathy. We measured concentrations of interleukin-6, 8 (IL-6, 8) and tumor necrosis factor (TNF)-alpha by enzyme-linked immunosorbent assay (ELISA) in vitreous and serum from 47 patients with proliferative diabetic retinopathy and 21 patients with vitreous noninflammatory retinopathies. Vitreous concentration of IL-6 were 64.7+/-12.8 pg/ml in proliferative diabetic retinopathy, much greater (P<.005) than in noninflammatory retinopathy (2.8+/-4.5 pg/ml). Amounts of IL-8 in vitreous fluid also were greater in proliferative retinopathy than in noninflammatory retinopathy (34.0+/-11.5 vs. 6.1+/-2.0 pg/ml, P<.005). Concentrations of TNF-alpha in vitreous fluid were not statistically different in proliferative retinopathy from those in noninflammatory retinopathy. In sera, concentrations of IL-6 and IL-8 were not different between proliferative and noninflammatory retinopathy. However, serum TNF-alpha was much greater in proliferative retinopathy than in noninflammatory retinopathy (0.81+/-0.72 vs. 0.09+/-0.00 pg/ml, P<.001). Elevated TNF-alpha in serum then may be diagnostically useful in proliferative diabetic retinopathy. And inflammatory cytokines in vitreous may be pathogenically important in this concentration.     

Increased plasma concentrations of osteoprotegerin in type 2 diabetic patients with microvascular complications

OBJECTIVE: Osteoprotegerin (OPG) is a newly identified inhibitor of bone resorption. Recent studies indicate that OPG also acts as an important regulatory molecule in the vasculature. Plasma levels of OPG seem to be elevated in subjects with diabetes as well as in non-diabetic subjects with cardiovascular disease. The aim of the present study was to examine the association between plasma OPG levels and microvascular complications and glycemic control in patients with type 2 diabetes. DESIGN AND METHODS: Four groups of 20 subjects in each, individually matched for age and gender, were included in the study: (i) subjects with normal glucose tolerance (NGT); (ii) subjects with impaired glucose tolerance (IGT); (iii) type 2 diabetic patients without retinopathy; and (iv) type 2 diabetic patients with diabetic maculopathy (DMa). Plasma concentration of OPG was measured in duplicate by a sandwich ELISA method. Furthermore, fundus photography, flourescein angiography, and measurements of urinary albumin excretion rate (RIA) were performed. RESULTS: Plasma OPG was significantly higher in diabetic (iii+iv) than in NGT (i) subjects (3.04+/-0.15 vs 2.54+/-0.16 ng/ml, P<0.05). Plasma OPG was significantly higher in the DMa (iv) group than in the NGT (i) group (3.25+/-0.23 vs 2.54+/-0.16 ng/ml, P=0.01). Moreover, plasma OPG was significantly higher (3.61+/-0.36 ng/ml) in the group of diabetic subjects with both microalbuminuria and DMa (n=7) than in the NGT (i) (2.54+/-0.16 ng/ml, P<0.01), IGT (ii) (2.82+/-0.21 ng/ml, P<0.05), and no retinopathy (iii) groups (2.83+/-0.20 ng/ml, P<0.05). CONCLUSIONS: We found increased levels of OPG in plasma from diabetic patients with microvascular complications. This finding indicates that OPG may be involved in the development of vascular dysfunction in diabetes [corrected].     

Increased plasma thrombin-activatable fibrinolysis inhibitor levels in normotensive type 2 diabetic patients with microalbuminuria

Hypofibrinolysis is a common finding in patients with diabetes mellitus and a risk factor for diabetic nephropathy. Recently, a new potent inhibitor of fibrinolysis, the thrombin-activatable fibrinolysis inhibitor (TAFI), has been isolated from human plasma. The possibility that TAFI also participates in the mechanism of hypofibrinolysis has not been appraised in diabetic patients with microalbuminuria. In the present study, we investigated the plasma levels of TAFI and its relation to urinary albumin excretion in normotensive diabetic patients with normo- and microalbuminuria. Thirty-nine normotensive nonobese type 2 diabetic patients (27 with normoalbuminuria, 12 with microalbuminuria) and 20 age-matched normal subjects were enrolled in this study. The plasma level of thrombin-antithrombin complex was significantly increased (22.1 +/- 2.6 vs. 8.3 +/- 1.0 nmol/liter; P < 0.05), whereas the D-dimer/thrombin-antithrombin complex ratio was significantly decreased (15.7 +/- 1.4 vs. 26.5 +/- 2.2; P < 0.05), showing the occurrence of hypercoagulability and hypofibrinolysis in diabetic patients. The plasma level of TAFI in diabetic patients was significantly elevated, compared with normal subjects (147.4 +/- 11.6 vs. 99.5 +/- 4.9%; P < 0.05). The plasma level of TAFI in diabetic patients with microalbuminuria was significantly higher than the level in diabetic patients with normoalbuminuria (194.1 +/- 24.5 vs. 128.8 +/- 12.3%; P < 0.02) or normal subjects (194.1 +/- 24.5 vs. 99.5 +/- 4.9%; P < 0.005). Univariate analysis showed that the plasma TAFI levels are significantly and proportionally correlated with urinary albumin excretion rate (r = 0.58; P < 0.005) and with plasma soluble thrombomodulin level, a marker of endothelial cell damage, in all diabetic patients (r = 0.42; P < 0.01). These data suggest that increased plasma level of TAFI may be involved in the mechanism of vascular endothelial damage in patients with type 2 diabetes mellitus.     

血浆纤维蛋白原在糖尿病视网膜病变患者中的水平及意义

目的 探讨血浆纤维蛋白原在糖尿病视网膜病变(DR)患者中的水平及意义.方法 886例2型糖尿病住院患者根据眼底照相结果,分为无视网膜病变组(NDR组,552例)和视网膜病变组(DR组,334例),比较两组间的一般资料和血浆纤维蛋白原水平的差异,Spearman法分析纤维蛋白原与DR相关性,二元Logistic回归法对其危险因素建立方程.结果 DR组血浆纤维蛋白原水平高于NDR组(t=-5.758,P＜0.001).并且,DR与纤维蛋白原呈正相关(r=0.177,P＜0.001).二元Logistic回归分析显示,糖尿病病程(OR=1.097,95％ CI:1.072～1.123)、血浆纤维蛋白原(OR=1.238,95％ CI:1.036～1.480)和糖尿病肾病(OR=3.534,95％ CI: 2.589～4.822)纳入回归方程(P均＜0.05),是DR的独立危险因素.进一步将DR组分为非增殖期视网膜病变组和增殖期视网膜病变组,结果显示随着DR病变程度的加重,血浆纤维蛋白原水平不断升高(F=19.963,P＜0.001).结论 DR患者体内血浆纤维蛋白原水平随着病变程度不断升高,是DR的独立危险因素.     

Evaluation of <Emphasis Type="Italic">N</Emphasis><Superscript>ε</Superscript>-(3-formyl-3,4-dehydropiperidino)lysine as a novel biomarker for the severity of diabetic retinopathy

AIMS/HYPOTHESIS: Recent studies suggest that oxidative stress should be monitored alongside HbA(1c) to identify subgroups of diabetic patients at high risk of initiation or progression of retinopathy. The acrolein-derived advanced lipoxidation end-product (ALE), [Formula: see text]-(3-formyl-3,4-dehydropiperidino)lysine (FDP-lysine), is a useful biomarker that reflects the cumulative burden of oxidative stress over long periods of time. The purpose of the present study was to investigate whether serum and haemoglobin levels of FDP-lysine are associated with the severity of diabetic retinopathy in type 1 and type 2 diabetic patients. METHODS: Serum and haemoglobin levels of FDP-lysine were measured by competitive ELISA in 59 type 1 and 76 type 2 diabetic patients with no retinopathy, non-proliferative retinopathy or proliferative retinopathy (mean age [+/-SEM] 54.3 +/- 1.3 years), and in 47 non-diabetic control individuals (mean age 51.9 +/- 2.1 years). RESULTS: Serum and haemoglobin levels of FDP-lysine were significantly increased in diabetic patients compared with control individuals (p = 0.04 and p = 0.002, respectively). However, no significant association was found between levels of serum FDP-lysine and the severity of diabetic retinopathy (p = 0.97). In contrast, increased haemoglobin FDP-lysine levels were observed in patients with proliferative retinopathy compared with patients without retinopathy and with non-proliferative retinopathy (p = 0.04). The relationship of FDP-lysine with proliferative retinopathy was unaltered after adjustment for HbA(1c), or other clinical parameters. CONCLUSIONS/INTERPRETATION: Our data suggest that haemoglobin FDP-lysine may provide a useful risk marker for the development of proliferative diabetic retinopathy independently of HbA(1c), and that elevated intracellular ALE formation may be involved in the pathogenesis of this sight-threatening complication of diabetes.