Active Proliferative Diabetic Retinopathy Research Articles

Expression of cyclo-oxygenase-2 and downstream enzymes in diabetic fibrovascular epiretinal membranes

Background/aims:The inducible enzyme cyclo-oxygense-2 (COX-2) and its metabolic products are important mediators for angiogenesis. We investigated the expression of COX-2 and its downstream enzymes microsomal prostaglandin-E synthase (mPGES)-1, cytosolic PGES...

OPPORTUNITY™

The mortality rate of maintenance hemodialysis (MHD) patients remains high. Measures of protein-energy wasting, including hypoalbuminemia, are strongly associated with their high mortality. Growth hormone (GH) may improve lean body mass (LBM) and serum albumin levels, and health-related quality of life (HRQoL), which are significantly and positively associated with survival in MHD patients. The OPPORTUNITY Trial will examine whether GH reduces mortality and morbidity and improves overall health in hypoalbuminemic MHD patients. The primary hypothesis is that daily recombinant human GH injections, compared with placebo, improve survival in hypoalbuminemic MHD patients. Secondary hypotheses are that GH improves morbidity and health, including number of hospitalized days, time to cardiovascular events, LBM, serum protein and inflammatory marker levels, exercise capacity, and HRQoL, and has a favorable safety profile. This is a prospective, double-blind, multicenter, randomized clinical trial involving 2500 MHD patients, up to 50% with diabetes mellitus, from 22 countries. Patients are randomized in a 1:1 ratio to receive daily injections of GH (20 microg/kg per day) or placebo for 104 weeks. Key inclusion criteria include clinically stable and well-dialyzed (Kt/V > or =1.2) adult MHD patients with serum albumin <4.0 g/dl. Exclusion criteria include active malignancy, active proliferative or severe nonproliferative diabetic retinopathy, uncontrolled hypertension, chronic use of high-dose glucocorticoids, or immunosuppressive agents and pregnancy. The OPPORTUNITY Trial is the first large-scale randomized clinical trial in adult MHD patients evaluating the response to GH of such clinical endpoints as mortality, morbidity, markers of body protein mass, inflammation, exercise capacity, and HRQoL.

Towards a blood test for diabetic retinopathy

Abstract Purpose Diabetic retinopathy (DR) is the leading cause of blindness among adults of working age in the UK. Early detection and appropriate management can prevent severe visual loss in 95% of cases. However, current screening methods are costly and suffer from subjective grading. Nucleic acids have been shown to circulate in plasma, with levels raised in conditions of cell death such as cancer and trauma. This study aimed to quantify circulatory retinal‐specific nucleic acids, and to evaluate potential for their use in the assessment of DR. Methods Diabetic patients (n = 106) and healthy controls (n = 24) were recruited from the Diabetes and Ophthalmology departments at St Thomas’ Hospital. RNA was extracted from whole blood, with quantitative real‐time RT‐PCR used to quantify mRNA levels for rhodopsin and RPE65, two proteins expressed exclusively in the retina. Beta‐actin mRNA was used for normalisation. Results Rhodopsin, RPE65 and beta‐actin mRNA were detected in 100% of subjects. Circulating rhodopsin and RPE65 mRNA levels were higher in diabetic patients than healthy individuals (p &lt; 0.02). Circulating rhodopsin mRNA was raised in all DR groups compared to healthy individuals, irrespective of presence or severity of DR (p &lt; 0.02). With respect to healthy controls, circulating RPE65 mRNA levels were higher in diabetic patients with background and proliferative DR (p &lt; 0.02). Patients with active proliferative DR (neovascularisation, vitreous and pre‐retinal haemorrhage, or retinal detachment) possessed higher RPE65 mRNA and lower rhodopsin mRNA levels than those with quiescent disease (p &lt; 0.01). Conclusion There is significant potential for use of these markers to screen for the presence of DR in diabetic patients in a quantitative manner using a blood test.

Intravitreal bevacizumab in active progressive proliferative diabetic retinopathy

Vitreous concentration of vascular endothelial growth factor (VEGF) rises significantly during proliferative diabetic retinopathy (PDR). Bevacizumab (Avastin) is a humanized monoclonal antibody to VEGF. Intravitreal administration of bevacizumab (IVB) has recently been shown to be effective in some ocular neovascularizations, including PDR. In this study we evaluate the efficacy of IVB in eyes with active, progressive PDR. In an interventional prospective case series, eyes with active, progressive PDR underwent one to three IVB injections (1.25 mg) at intervals of either 6 or 12 weeks. Complete ophthalmic examinations and color fundus photography were performed at baseline and 1, 6, 12, and 20 weeks after the first injection. Fluorescein angiography (FA) was performed before injection and 20 weeks after. The primary outcome measures were clearing of vitreous hemorrhage (VH) and regression of active fibrovascular tissue (FVT). The secondary outcomes were any change in best-corrected visual acuity (BCVA) and any incidence of adverse events. Thirty eight eyes of 38 patients with a mean age of 54.7 +/- 10.1 years were included in the study. VH resolved significantly after 1 week (P = 0.014), 12 weeks (P = 0.0001), and 20 weeks (P = 0.002). The vascular component of FVT regressed, though the FVT area did not change. Mean BCVA improved significantly compared to baseline at all follow-up examinations. Two cases showing moderate fibrous proliferation developed traction retinal detachment (TRD). IVB has significant therapeutic effect on eyes with active, progressive PDR: the treatment causes a significant amount of VH resolution and neovessel regression. At the same time, this procedure may increase the risk of TRD in eyes with fibrous proliferation.

Bevacizumab Pretreatment and Long-acting Gas Infusion on Vitreous Clear-up After Diabetic Vitrectomy

To evaluate the effects of bevacizumab pretreatment combined with intravitreal infusion of C3F8 10% on the clearance speed of early postoperative vitreous hemorrhage in diabetic vitrectomy for eyes with active fibrovascular proliferation. Prospective, nonrandomized, comparative case study. Sixteen eyes (15 patients) that underwent primary pars plana vitrectomy for active proliferative diabetic retinopathy (PDR) were prospectively enrolled with a follow-up period of six months or more. These cases received an intravitreal injection of bevacizumab (1.25 mg/0.05 ml) one week prior to surgery and intravitreal C3F8 10% infusion during surgery. The severity of intraoperative bleeding, vitreous clear-up time, percentage of prolonged vitreous clear-up (> or = three weeks), and recurrent hemorrhage respectively were compared with those in a control group (24 eyes in 24 patients) that received gas infusion alone. The severity of intraoperative bleeding was significantly lower in the study group than in the control group. Vitreous clear-up time for the study group and the control group was 7.2 +/- 5.6 days and 15.2 +/- 11.4 days, respectively (P = .04). Prolonged vitreous clear-up time (> or = three weeks) was observed in one of 16 (6.3%) and nine of 24 (37.5%) of the cases, respectively (P = .03). Early recurrent vitreous hemorrhage rates in the two groups were zero of 16 (0%) and one of 24 (4.2%), respectively (P = .41). Multiple logistic regression analyses showed that bevacizumab pretreatment reduced vitreous clear-up time. Bevacizumab pretreatment combined with C3F8 10% infusion could be an effective adjunct to vitrectomy in accelerating postoperative vitreous clear-up for eyes with active PDR.

Substance P and secretoneurin in vitreous aspirates of patients with various vitreoretinal diseases

By means of highly sensitive radioimmunoassays, the levels of substance P (SP) and secretoneurin (SN) were detected in vitreous aspirates of patients with macular holes which served as controls, in patients with nonproliferative diabetic retinopathy (DR), active proliferative diabetic retinopathy (active PDR), inactive PDR, rhegmatogenous retinal detachment and proliferative vitreoretinopathy (PVR). Furthermore, SN-like immunoreactivities were characterized by reversed phase-HPLC. The concentration of SN was more than 20-fold higher in macular holes when compared with SP and reversed phase HPLC revealed evidence that the vitreous levels of SN represent authentic SN. SN was significantly decreased in patients with nonproliferative DR, active PDR and inactive PDR by more than 70% which seems to result from a reduced expression and/or secretion from the cilary epithelium and a reduced release from the retina both due to diabetes mellitus. By contrast SP was increased in rhegmatogenous retinal detachment most obviously due to an enhanced outflow of the peptide through retinal breaks. Despite their proangiogenic activities, SP and SN are unlikely to be involved in the pathogenesis of neovascularizations in DR because of their unchanged and reduced levels, respectively, but the low levels of both peptides may facilitate the regression of vasoproliferations following laser photocoagulation.

Optos Panoramic200A™ Fluorescein Angiography for Proliferative Diabetic Retinopathy with Asteroid Hyalosis

We report a unique situation in which the use of Optos Panoramic200A™ fluorescein angiography directed the management of a patient with asteroid hyalosis and active proliferative diabetic retinopathy. The Optos Panoramic200A™ system provides a 200 degrees field of view, which may be useful in selected cases where simultaneous view of the posterior pole and periphery is important. The Optos fluorescein angiogram directed the management of our patient with proliferative diabetic retinopathy combined with asteroid hyalosis.

Chemokines in proliferative diabetic retinopathy and proliferative vitreoretinopathy.

To determine levels of the chemokines CCL1/I-309, CCL2/MCP-1, CCL3/MIP-1alpha, CCL4/MIP-1beta, CCL7/MCP-3, CCL8/MCP-2, CXCL5/ENA-78, CXCL6/GCP-2, CXCL10/IP-10, and CXCL11/I-TAC in the vitreous humor and serum, from patients with proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), and rhegmatogenous retinal detachment with no PVR (RD), and to investigate the expression of MCP-1, CXCL12/SDF-1, and the chemokine receptor CXCR3 in epiretinal membranes. Paired vitreous humor and serum samples were obtained from patients undergoing vitrectomy for the treatment of RD (57 specimens), PVR (32 specimens), and PDR (88 specimens). The levels of chemokines were measured by enzyme-linked immunosorbent assays. Eighteen PDR and 5 PVR membranes were studied by immunohistochemical techniques. Of all the chemokines studied, only MCP-1 and IP-10 were detected in vitreous humor samples. MCP-1 levels in vitreous humor samples were significantly higher than in serum samples (p < 0.001). MCP-1 levels were significantly higher in vitreous humor samples from patients with PVR and PDR compared with RD (p = 0.0002). MCP-1 levels in vitreous humor samples from patients with active PDR were significantly higher than in inactive PDR cases (p = 0.0224). IP-10 levels in vitreous humor samples were significantly higher than in serum samples (p = 0.0035). IP-10 levels were significantly higher in vitreous humor samples from patients with PVR and PDR compared with RD (p = 0.0083). The incidence of IP-10 detection in vitreous humor samples was significantly higher in active PDR cases compared with inactive cases (p = 0.0214). There was a significant association between the incidence of IP-10 detection and increased levels of MCP-1 in vitreous humor samples from all patients, and patients with RD and PDR (p < 0.001 for all comparisons). MCP-1, and SDF-1 were localized in myofibroblasts in PVR and PDR membranes and in vascular endothelial cells in PDR membranes. CXCR3 was expressed by vascular endothelial cells in PDR membranes. MCP-1, IP-10 and SDF-1 may participate in pathogenesis of PVR and PDR. Myofibroblasts and vascular endothelial cells are the major cell types expressing MCP-1, SDF-1, and CXCR3 in epiretinal membranes.

Differential Expression of Vitreous Proteins in Proliferative Diabetic Retinopathy

Purpose: To identify vitreous proteins that were differentially expressed in patients suffering from proliferative diabetic retinopathy with active neovascularization. Methods: The vitreous samples of 15 active proliferative diabetic retinopathy patients were analyzed by two-dimensional gel electrophoresis and mass spectrometry, and the results were compared with those from age-matched patients with macular hole. Results: Twenty-five protein spots were identified in the two-dimensional gel electrophoresis gels. Eight proteins (pigmented epithelium derived factor, serine protease inhibitor, apolipoprotein A-IV precursor, prostaglandin-H2 D-isomerase, α1-antitrypsin precursor, ankyrin repeat domain 15 protein, alpha2-HS-glycoprotein, and beta V spectrin) in the 25 spots were expressed significantly differently between the macular hole and proliferative diabetic retinopathy patients (p value < 0.05). Five proteins were upregulated in the proliferative diabetic retinopathy patients, and three were downregulated (p value < 0.05). Conclusions: We constructed vitreous protein profiles for proliferative diabetic retinopathy patients and identified eight candidate proteins believed to be involved in the pathogenesis of proliferative diabetic retinopathy.

Interleukin‐8, monocyte chemoattractant protein‐1 and IL‐10 in the vitreous fluid of patients with proliferative diabetic retinopathy

To determine the intra-vitreous levels of two pro-inflammatory cytokines [interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1)] and the anti-inflammatory cytokine interleukin-10 (IL-10) in patients with proliferative diabetic retinopathy (PDR). In addition, the relationship between the profile of cytokines and PDR activity has also been evaluated. The study included 22 consecutive diabetic patients with PDR (4 Type 1 and 18 Type 2) on whom a vitrectomy was performed. Sixteen age-matched non-diabetic patients with other conditions requiring vitrectomy, but in which the retina was not directly affected by neovascularization served as a control group. IL-8, MCP-1 and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA). The vitreal levels of both IL-8 and MCP-1 were strikingly higher in diabetic patients with PDR in comparison with the control group [173.5 (64-1670) vs. 49 pg/ml (25-145), P < 0.001, and 2171 (388-6155) vs. 438 pg/ml (207-1344), P < 0.001, respectively]. In addition, the vitreous concentrations of IL-8 and MCP-1 were higher in patients with active PDR than in those patients with quiescent PDR [324.5 (80-1670) vs. 173.5 pg/ml (64-487), P = 0.06 and 3596 (1670-6155) vs. 1143 pg/ml (388-2500), P = 0.01, respectively]. However, vitreal levels of IL-10 in diabetic patients were similar to that obtained in the control group [2.89 (1.55-5.50) vs. 2.46 pg/ml (2.2-5.41), P = NS]. The pro-inflammatory cytokines IL-8 and MCP-1 are increased in the vitreous fluid of PDR patients without an increase in the anti-inflammatory cytokine IL-10. In addition, both IL-8 and MCP-1 intra-vitreous levels correlated with PDR activity, thus suggesting that these cytokines may be pathogenically important in PDR.

Pars plana vitrectomy with removal of the internal limiting membrane in the treatment of persistent diabetic macular edema

To evaluate the benefit of pars plana vitrectomy (PPV) and removal of the internal limiting membrane (ILM) in eyes with diffuse diabetic macular edema refractory to laser photocoagulation. Prospective, consecutive, interventional case series. Diabetic patients with biomicroscopic, angiographic, and tomographic evidence of diabetic macular edema persisting for at least 3 months after numerous sessions of macular photocoagulation were evaluated for inclusion. Patients with biomicroscopic evidence of epiretinal membrane or taut posterior hyaloid, previous vitreoretinal surgery, or active proliferative diabetic retinopathy were excluded. The main outcome measures were macular thickness, as measured by optical coherence tomography (OCT) and visual acuity (VA). PPV with ILM removal was performed in 11 eyes of 10 patients (four men, six women; mean age = 58.2 years). Six-month follow-up data were available for 10 eyes (91%). At 6 months postoperatively, central macular thickness had improved by at least 20% in eight of 11 eyes (mean preoperative thickness of 421 mum compared with mean postoperative thickness of 188 mum; P = .007). Mean VA improved from 20/352 to 20/94 at 6 months (P = .002). By the most recent visit (range = 6-20 months postoperatively), VA had improved by at least 2 Snellen lines in 6 of 10 eyes treated with surgery alone. The early results of this ongoing study suggest that PPV with ILM removal may provide anatomic and visual benefit in some eyes with chronic diabetic macular edema unresponsive or unamenable to additional laser photocoagulation.

Vitreous levels of angiopoietin 2 and vascular endothelial growth factor in patients with proliferative diabetic retinopathy

To investigate the levels of angiopoietin-2 (Ang2) and vascular endothelial growth factor (VEGF) in the vitreous fluids of patients with proliferative diabetic retinopathy (PDR) and to ascertain their involvement, if any, in angiogenesis of PDR. Retrospective case-control study. Forty-one eyes of 41 patients with proliferative diabetic retinopathy and 18 eyes of 18 patients with nondiabetic ocular diseases (control group). Nondiabetic control eyes included 11 with idiopathic macular hole and 7 with idiopathic epiretinal membrane. Vitreous fluid samples were obtained at vitrectomy, and the levels of Ang2 and VEGF were measured by enzyme-linked immunosorbent assay. Vitreous level (mean +/- SD) of Ang2 was significantly higher in patients with PDR (1,753 +/- 3,213 pg/ml) than in control patients (112 +/- 113 pg/ml) (P < .0001). The vitreous concentration of VEGF was also significantly higher in patients with PDR (812 +/- 1,108 pg/ml) than in control patients (1.7 +/- 4.4 pg/ml) (P < .0001). Both Ang2 and VEGF levels in eyes with active PDR were significantly higher than in those with inactive PDR. The vitreous concentration of Ang2 correlated significantly with that of VEGF in eyes with proliferative diabetic retinopathy ([correlation coefficient] rho = 0.497, P = .001). These data demonstrate an increase of Ang2 in the vitreous fluid of patients with PDR and suggest an association of Ang2 and VEGF with angiogenic activity in PDR.

Aqueous humor levels of cytokines are related to vitreous levels and progression of diabetic retinopathy in diabetic patients.

Cytokine levels are elevated in the ocular fluid of diabetic patients. It is unclear whether aqueous humor levels of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) are related to the vitreous fluid levels of these substances and to the progression of diabetic retinopathy. Aqueous humor and vitreous fluid samples were obtained during cataract and vitreous surgery from ten eyes of ten patients with diabetic macular edema and 26 eyes of 26 patients with proliferative diabetic retinopathy (PDR). The VEGF and IL-6 levels in aqueous humor, vitreous fluid, and plasma were measured by enzyme-linked immunosorbent assay. VEGF and IL-6 levels in aqueous humor were significantly correlated with those in vitreous fluid (rho=0.793 and rho=0.737, respectively). VEGF levels in aqueous humor and vitreous fluid were significantly correlated with the corresponding IL-6 levels (rho=0.631 and rho=0.687, respectively). The aqueous and vitreous levels of VEGF were significantly correlated with the severity of diabetic retinopathy (rho=0.659 and rho=0.771, respectively). Aqueous and vitreous levels of IL-6 were also significantly correlated with the severity of diabetic retinopathy (rho=0.742 and rho=0.746, respectively). Aqueous and vitreous levels of both VEGF and IL-6 were significantly higher in the patients with active PDR than those in quiescent PDR. Our results suggest that there is a significant relationship between VEGF and IL-6 levels in aqueous humor and in vitreous fluid. Measurement of the aqueous levels of VEGF and IL-6 may be useful to analyze the pathogenesis of diabetic retinopathy and to predict disease activity.

Vitreous levels of pigment epithelium-derived factor and vascular endothelial growth factor: implications for ocular angiogenesis*1

Purpose Pigment epithelium-derived factor (PEDF) has been demonstrated to suppress ocular angiogenesis in several animal models. In this study, we sought to measure the levels of PEDF and vascular endothelial growth factor (VEGF) in the vitreous of patients with and without ocular neovascular disorders. Design Case-control study of patients undergoing intraocular surgery for a variety of neovascular and nonneovascular conditions. Methods Vitreous samples were collected from 65 eyes of 65 patients with no neovascular disorder (n = 24), choroidal neovascularization (n = 9), active proliferative diabetic retinopathy (n = 16), and inactive proliferative diabetic retinopathy (n = 16). The levels of VEGF and PEDF in these vitreous samples were determined by enzyme-linked immunosorbent assay. Results The VEGF levels were at or below the level of detectability in the reference and choroidal neovascularization groups. The VEGF levels were significantly elevated in both the active and inactive PDR groups, and significantly higher in the active PDR group as compared with the inactive PDR group. The PEDF levels, which were present at relatively high concentrations in all groups, were higher in patients with active PDR compared with the control and choroidal neovascularization groups. Conclusions High levels of immunoreactive PEDF are present in the vitreous of individuals with or without ocular neovascularization, but PEDF levels are significantly higher in patients with active PDR compared with patients with choroidal neovascularization or nonneovascular retinal diseases. Although these results do not preclude the possibility that endogenous PEDF helps to modulate ocular neovascularization, they do not support ischemia-induced downregulation of PEDF as a mechanism for such modulation.

Vitreous levels of pigment epithelium-derived factor and vascular endothelial growth factor: implications for ocular angiogenesis

Purpose Pigment epithelium-derived factor (PEDF) has been demonstrated to suppress ocular angiogenesis in several animal models. In this study, we sought to measure the levels of PEDF and vascular endothelial growth factor (VEGF) in the vitreous of patients with and without ocular neovascular disorders. Design Case-control study of patients undergoing intraocular surgery for a variety of neovascular and nonneovascular conditions. Methods Vitreous samples were collected from 65 eyes of 65 patients with no neovascular disorder (n = 24), choroidal neovascularization (n = 9), active proliferative diabetic retinopathy (n = 16), and inactive proliferative diabetic retinopathy (n = 16). The levels of VEGF and PEDF in these vitreous samples were determined by enzyme-linked immunosorbent assay. Results The VEGF levels were at or below the level of detectability in the reference and choroidal neovascularization groups. The VEGF levels were significantly elevated in both the active and inactive PDR groups, and significantly higher in the active PDR group as compared with the inactive PDR group. The PEDF levels, which were present at relatively high concentrations in all groups, were higher in patients with active PDR compared with the control and choroidal neovascularization groups. Conclusions High levels of immunoreactive PEDF are present in the vitreous of individuals with or without ocular neovascularization, but PEDF levels are significantly higher in patients with active PDR compared with patients with choroidal neovascularization or nonneovascular retinal diseases. Although these results do not preclude the possibility that endogenous PEDF helps to modulate ocular neovascularization, they do not support ischemia-induced downregulation of PEDF as a mechanism for such modulation.

Accumulation of NH2-terminal fragment of connective tissue growth factor in the vitreous of patients with proliferative diabetic retinopathy.

To evaluate the expression of connective tissue growth factor (CTGF) and its fragments in the vitreous of patients with proliferative diabetic retinopathy (PDR) and to localize CTGF expression in associated preretinal membranes. Vitreous was obtained from 24 patients with active PDR, 4 patients with quiescent PDR, and 23 patients with other retinal diseases and no diabetes, including 5 patients with vitreous hemorrhage. Enzyme-linked immunosorbent assay was used to determine levels of whole CTGF and its NH2- and COOH-terminal fragments. Preretinal membranes from three patients with active PDR were stained immunohistochemically for the presence of CTGF and cell type-specific markers. A significant increase in NH2-terminal CTGF fragment content was found in vitreous samples from patients with active PDR when compared with samples from nondiabetic patients (P<0.0001) or patients with quiescent PDR (P=0.02). Levels of NH2-terminal CTGF were also greater in vitreous samples from diabetic patients with vitreous hemorrhage compared with samples from nondiabetic patients with vitreous hemorrhage (P=0.02). Vitreous levels of whole CTGF were similar in all groups. COOH-terminal fragments of CTGF were not detected. CTGF immunoreactivity was predominantly localized to smooth muscle actin-positive myofibroblasts within active PDR membranes. -NH2-terminal CTGF fragment content is increased in the vitreous of patients with active PDR, suggesting that it plays a pathogenic role or represents a surrogate marker of CTGF activity in the disorder. The localization of CTGF in myofibroblasts suggests a local paracrine mechanism for induction of fibrosis and neovascularization.

Possible Involvement of Nitric Oxide in the Progression of Diabetic Retinopathy

Abnormal nitric oxide (NO) synthesis has been implicated in the pathogenesis of diabetes mellitus. The aim of our study was to elucidate the relationship between the stages of diabetic retinopathy (DR) and the NO levels in aqueous humor and plasma. Using the chemiluminescence assay, we measured the concentrations of NO in aqueous humor and plasma samples obtained during intraocular surgery from 45 diabetic patients and 19 nondiabetic cataract patients. The patients with diabetes were classified into 4 groups: proliferative DR (PDR) with active neovascularization (active PDR; 9 cases), PDR with quiescent neovascularization (regressed PDR; 6 cases), background DR (BDR; 16 cases) and no DR (14 cases). We found that the aqueous NO levels (mean ± SE) of the active PDR group (83.2 ± 13.9 µM) were significantly higher than those of the BDR group (45.8 ± 6.0 µM, p = 0.049) and the diabetics without DR (33.3 ± 5.2 µM, p = 0.011), and, although not statistically significantly, they were also higher than those of the regressed PDR group (52.1 ± 10.3 µM, p = 0.224). However, no significant differences were observed between any of the diabetic subgroups in the plasma NO levels (p = 0.345). We therefore concluded that NO present in the ocular tissues may play important roles in the progression of DR.

Elevated immunoreactive-adrenomedullin levels in the aqueous humor of patients with uveitis and vitreoretinal disorders

To clarify possible involvement of adrenomedullin in the pathophysiology of inflammation of eyes, we measured immunoreactive-adrenomedullin concentrations in the aqueous humor and plasma obtained from 14 control subjects and 56 patients with uveitis or vitreoretinal disorders. Immunoreactive-adrenomedullin levels in the aqueous humor were significantly elevated in patients with active uveitis, proliferative vitreoretinopathy and proliferative diabetic retinopathy, as compared with control subjects. The plasma immunoreactive-adrenomedullin levels were not significantly correlated with the aqueous humor levels. These findings suggest that adrenomedullin produced locally in the eyes is involved in the pathophysiology of uveitis and some proliferative vitreoretinal disorders.

Free insulin growth factor-I and vascular endothelial growth factor in the vitreous fluid of patients with proliferative diabetic retinopathy

PURPOSE: To investigate the relationship between insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor (VEGF) in the vitreous fluid of diabetic patients with proliferative diabetic retinopathy (PDR). DESIGN: Observational case-control study. METHODS: In a prospective study, 37 consecutive diabetic patients with PDR (14 type I and 23 type II diabetes mellitus) in whom a vitrectomy was performed were compared with 21 nondiabetic patients with other conditions requiring vitrectomy (control group). Free IGF-I and VEGF were measured by ELISA. RESULTS: Vitreal levels of both free IGF-1 and VEGF were higher in diabetic patients with PDR than in control subjects ( P < .01, and P < .0001, respectively). After adjusting for total intravitreous protein concentration, VEGF (ng/mg of proteins) remained significantly higher in diabetic patients with PDR than in the control group ( P < .0001), whereas free IGF-I (ng/mg of proteins) was lower in diabetic patients than in control subjects ( P < .0001). The vitreous concentrations of VEGF were higher in patients with active PDR than in patients with quiescent PDR ( P < .005), whereas vitreous free IGF-I was not related to PDR activity. Finally, we did not observe a correlation between the vitreal levels of free IGF-I and VEGF. CONCLUSIONS: We conclude that free IGF-I and VEGF are both increased, but not related, within the vitreous fluid of diabetic patients with PDR. In addition, our results support the current concept that VEGF is directly involved in the pathogenesis of PDR, whereas the precise role of free IGF-I remains to be established.

Unbalanced vitreous levels of pigment epithelium-derived factor and vascular endothelial growth factor in diabetic retinopathy

PURPOSE: To determine the levels of pigment epithelium-derived factor (PEDF) and vascular endothelial growth factor (VEGF) in the vitreous of patients with diabetic retinopathy (DR). DESIGN: Experimental study of PEDF and VEGF levels in vitreous samples collected during vitrectomy. METHODS: The levels of PEDF and VEGF were measured by enzyme-linked immunosorbent assay in the vitreous of 46 eyes of 43 patients who underwent vitrectomy with diabetic retinopathy (DR) (32 eyes of 29 patients) and an idiopathic macular hole (MH) (14 eyes of 14 patients). RESULTS: The vitreal concentration of PEDF was significantly lower at 1.11 ± 0.14 μg/ml (mean ± standard error) in eyes with DR than in eyes with MH at 1.71 ± 0.22 μg/ml ( P = .021). The VEGF level was 1799 ± 478 pg/ml in eyes with DR and not detectable in MH. The PEDF level in proliferative DR (PDR) (0.94 ± 0.12 μg/ml) was lower than that in nonproliferative DR (NPDR) (2.25 ± 0.32 μg/ml), and that in active DR (0.85 ± 0.14 μg/ml) was significantly lower than that in inactive DR (1.59 ± 0.24 μg/ml; P = .01). The VEGF level was 2025 ± 533 pg/ml in PDR and 215 ± 201 pg/ml in NPDR and that in active DR (2543 ± 673 pg/ml) was significantly higher than that in inactive DR (395 ± 188 pg/ml; P = .0098). CONCLUSIONS: These results suggest that lower levels of PEDF and higher levels of VEGF may be related to the angiogenesis in DR that leads to active PDR.