VEGF-Independent Activation of Müller Cells by the Vitreous from Proliferative Diabetic Retinopathy Patients.

Proliferative diabetic retinopathy (PDR), a major complication of diabetes mellitus, results from an inflammation-sustained interplay among endothelial cells, neurons, and glia. Even though anti-vascular endothelial growth factor (VEGF) interventions represent the therapeutic option for PDR, they are only partially efficacious. In PDR, Müller cells undergo reactive gliosis, produce inflammatory cytokines/chemokines, and contribute to scar formation and retinal neovascularization. However, the impact of anti-VEGF interventions on Müller cell activation has not been fully elucidated. Here, we show that treatment of MIO-M1 Müller cells with vitreous obtained from PDR patients stimulates cell proliferation and motility, and activates various intracellular signaling pathways. This leads to cytokine/chemokine upregulation, a response that was not mimicked by treatment with recombinant VEGF nor inhibited by the anti-VEGF drug ranibizumab. In contrast, fibroblast growth factor-2 (FGF2) induced a significant overexpression of various cytokines/chemokines in MIO-M1 cells. In addition, the FGF receptor tyrosine kinase inhibitor BGJ398, the pan-FGF trap NSC12, the heparin-binding protein antagonist N-tert-butyloxycarbonyl-Phe-Leu-Phe-Leu-Phe Boc2, and the anti-inflammatory hydrocortisone all inhibited Müller cell activation mediated by PDR vitreous. These findings point to a role for various modulators beside VEGF in Müller cell activation and pave the way to the search for novel therapeutic strategies in PDR.

PEELING OF THE INTERNAL LIMITING MEMBRANE WITH FOVEAL SPARING FOR TREATMENT OF DEGENERATIVE LAMELLAR MACULAR HOLE.

PURPOSE: To compare the functional and anatomical results of fovea-sparing internal limiting membrane peeling during vitrectomy with those of observation for degenerative lamellar macular hole with lamellar hole-associated epiretinal proliferation. DESIGN: A prospective, randomized, comparative pilot study. METHODS: Thirty-six eyes were randomized to undergo surgery with foveal internal limiting membrane sparing (Group S) or observation only (Group C). The main outcome measures were foveal retinal sensitivity, visual acuity, and central retinal thickness. RESULTS: After 6 months, a significant difference was found in foveal retinal sensitivity between Group S (12.8 ± 1.7 dB) and Group C (9.39 ± 1.8 dB; P < 0.001). Similarly, best-corrected visual acuity improved in Group S and remained stable in Group C (respectively, 0.17 ± 0.13 and 0.46 ± 0.21 logMAR; P < 0.001). A significant increase in central retinal thickness was observed in Group S, but not in Group C (272 ± 24 vs. 147 ± 20 µm, P < 0.001). CONCLUSION: Fovea-sparing internal limiting membrane peeling is a feasible treatment for degenerative lamellar macular hole with lamellar hole-associated epiretinal proliferation, yielding better improvements in best-corrected visual acuity and foveal retinal sensitivity than observation alone. Further studies are needed to optimize this new surgical approach.

FOVEA-SPARING VERSUS COMPLETE INTERNAL LIMITING MEMBRANE PEELING IN VITRECTOMY FOR THE TREATMENT OF MACULAR HOLES.

PURPOSE: To compare the anatomical and functional outcomes of vitrectomy involving complete internal limiting membrane peeling (CP) with those of vitrectomy involving fovea-sparing internal limiting membrane peeling (FSP) for the treatment of macular holes measuring >250 µm. METHODS: This prospective, randomized, comparative study included 46 eyes with a medium or large macular hole that was randomized to undergo complete (CP group) or fovea-sparing (FSP group) internal limiting membrane peeling during vitrectomy. The main outcome measures included the foveal retinal sensitivity, visual acuity, and central retinal thickness. RESULTS: Both groups showed significantly improved foveal retinal sensitivity after surgery; the mean foveal retinal sensitivity change at 12 months after surgery was +2.8 ± 2.1 dB in the CP group and +7.2 ± 2.3 dB in the FSP group. The visual acuity also showed a significant improvement in both groups, with no significant differences in values at any time point. Regarding central retinal thickness, there was a significant decrease in the CP group and no change in the FSP group. Nicks or dimples in the inner retinal layers were visible in the fovea and perifovea of nine eyes in the CP group. CONCLUSION: Our findings suggest that both CP and FSP are safe and effective treatments leading to functional and anatomical improvements in patients with all size macular holes. However, the fovea-sparing technique may provide better functional outcomes because of a greater improvement in foveal retinal sensitivity.

Human vitreous in proliferative diabetic retinopathy: Characterization and translational implications.

Diabetic retinopathy (DR) is one of the leading causes of visual impairment in the working-age population. DR is a progressive eye disease caused by long-term accumulation of hyperglycaemia-mediated pathological alterations in the retina of diabetic patients. DR begins with asymptomatic retinal abnormalities and may progress to advanced-stage proliferative diabetic retinopathy (PDR), characterized by neovascularization or preretinal/vitreous haemorrhages. The vitreous, a transparent gel that fills the posterior cavity of the eye, plays a vital role in maintaining ocular function. Structural and molecular alterations of the vitreous, observed during DR progression, are consequences of metabolic and functional modifications of the retinal tissue. Thus, vitreal alterations reflect the pathological events occurring at the vitreoretinal interface. These events are caused by hypoxic, oxidative, inflammatory, neurodegenerative, and leukostatic conditions that occur during diabetes. Conversely, PDR vitreous can exert pathological effects on the diabetic retina, resulting in activation of a vicious cycle that contributes to disease progression. In this review, we recapitulate the major pathological features of DR/PDR, and focus on the structural and molecular changes that characterize the vitreal structure and composition during DR and progression to PDR. In PDR, vitreous represents a reservoir of pathological signalling molecules. Therefore, in this review we discuss how studying the biological activity of the vitreous in different in vitro, ex vivo, and in vivo experimental models can provide insights into the pathogenesis of PDR. In addition, the vitreous from PDR patients can represent a novel tool to obtain preclinical experimental evidences for the development and characterization of new therapeutic drug candidates for PDR therapy.

Treatment of exudative age-related macular degeneration with aflibercept combined with pranoprofen eye drops or nutraceutical support with omega-3: A randomized trial.

AIMS: The aim of this study was to determine whether a combination of intravitreal aflibercept (IVA) and pranoprofen eyedrops or nutraceutical support provides additional benefit over IVA monotherapy for the treatment of choroidal neovascularization (CNV) in age-related macular degeneration. METHODS: This was a prospective, randomized, pilot study in 60 patients with treatment-naïve CNV. Patients were randomized 1:1:1 into three groups: aflibercept monotherapy (AM), aflibercept plus pranoprofen (AP) or aflibercept plus nutraceutical (AN) tablets containing multivitamin antioxidant and mineral supplementation plus omega-3. RESULTS: At 12 months, all groups showed significant improvement in both best-corrected visual acuity (BCVA) and central retinal thickness (CRT). The mean BCVA change from baseline to 12 months was -0.26 ± 0.06 LogMAR, -0.30 ± 0.06 LogMAR and -0.24 ± 0.04 LogMAR in the AM, AP and AN groups, respectively. The mean CRT change from baseline to 12 months was -76.9 ± 10.9 µm, -129 ± 19.9 µm and -105 ± 11.6 µm in the AM, AP and AN groups, respectively. The AN group required one less IVA injection than the AM group. CONCLUSIONS: Compared with AM, both combination groups acted synergistically, although no significant benefits in BCVA were found over AM. Nutraceutical support with omega-3 leads to a reduced need for IVA.

EPIRETINAL MEMBRANE REMOVAL WITH FOVEAL-SPARING INTERNAL LIMITING MEMBRANE PEELING: A Pilot Study.

PURPOSE: To compare the retinal sensitivity after complete internal limiting membrane (ILM) peeling with that after foveal-sparing ILM peeling during vitrectomy for Type I epiretinal membrane. METHODS: This was a prospective, randomized, comparative study. Thirty-eight eyes were randomized to undergo complete peeling of the ILM (CP group) or peeling with foveal sparing (FS group). The main outcome measures were foveal and perifoveal retinal sensitivity, visual acuity, and central retinal thickness. RESULTS: Foveal retinal sensitivity showed a significant improvement in the FS group (2.82 ± 0.85 dB, P = 0.037) versus a slight drop in the CP group (-0.66 ± 0.48 dB, P = 1). Perifoveal retinal sensitivity slightly improved in both groups (0.47 ± 0.37 dB, P = 1 in the CP group and 0.79 ± 0.42 dB, P = 0.77 in the FS group), showing a similar trend without significant differences. Significant improvements were observed in both visual acuity and central retinal thickness in both groups. However, three cases in the FS group showed epiretinal membrane recurrence and required revision surgery with complete ILM removal. CONCLUSION: Internal limiting membrane peeling may reduce retinal sensitivity and significantly increase the incidence of microscotomas. However, the higher epiretinal membrane recurrence rate after the foveal-sparing technique limits the effectiveness of this procedure. Further studies must be conducted to determine if it is safe to leave a portion of the ILM in front of the fovea.

3D endothelial cell spheroid/human vitreous humor assay for the characterization of anti-angiogenic inhibitors for the treatment of proliferative diabetic retinopathy.

Proliferative diabetic retinopathy (PDR) represents a main cause of acquired blindness. Despite the recognition of the key role exerted by vascular endothelial growth factor (VEGF) in the pathogenesis of PDR, limitations to anti-VEGF therapies do exist. Thus, rapid and cost-effective angiogenesis assays are crucial for the screening of anti-angiogenic drug candidates for PDR therapy. In this context, evaluation of the angiogenic potential of PDR vitreous fluid may represent a valuable tool for preclinical assessment of angiostatic molecules. Here, vitreous fluid obtained from PDR patients after pars plana vitrectomy was used as a pro-angiogenic stimulus in a 3D endothelial cell spheroid/human vitreous assay. The results show that PDR vitreous is able to stimulate the sprouting of fibrin-embedded HUVEC spheroids in a time- and dose-dependent manner. A remarkable variability was observed among 40 individual vitreous fluid samples in terms of sprouting-inducing activity that was related, at least in part, to defined clinical features of the PDR patient. This activity was hampered by various extracellular and intracellular signaling pathway inhibitors, including the VEGF antagonist ranibizumab. When tested on 20 individual vitreous fluid samples, the inhibitory activity of ranibizumab ranged between 0 and 100% of the activity measured in the absence of the drug, reflecting a variable contribution of angiogenic mediators distinct from VEGF. In conclusion, the 3D endothelial cell spheroid/human vitreous assay represents a rapid and cost-effective experimental procedure suitable for the evaluation of the anti-angiogenic activity of novel extracellular and intracellular drug candidates, with possible implications for the therapy of PDR.

Comparison of half-dose photodynamic therapy and 689 nm laser treatment in eyes with chronic central serous chorioretinopathy.

PURPOSE: To compare visual and anatomical outcomes between half-dose photodynamic therapy (hd-PDT) and 689 nm laser therapy (689-LT) in chronic central serous chorioretinopathy (CSC). METHODS: Forty eyes of 40 patients with symptomatic chronic CSC were randomized in a 1:1 ratio to receive either hd-PDT or 689-LT delivering 95 J/cm2 via an intensity application of 805 mW/cm2 over 118 s. Best-corrected visual acuity (BCVA) and spectral-domain optical coherence tomography findings were compared between the two treatment groups. RESULTS: Mean CSC duration was 17.1 ± 6.66 weeks and 18.7 ± 7.46 weeks in the hd-PDT and 689-LT groups respectively. Both groups showed significant BCVA improvements, as well as reductions in central retinal and subfoveal choroidal thickness. Although hd-PDT led to a faster reduction in central retinal thickness, no significant differences were recorded between groups for any other measured parameter at any time point. Complete photoreceptor recovery was observed in eight and seven eyes in the hd-PDT and 689-LT groups respectively. CONCLUSIONS: Both hd-PDT and 689-LT were effective at treating chronic CSC. Further studies are warranted to evaluate long-term safety and efficacy.

Inflammation and N-formyl peptide receptors mediate the angiogenic activity of human vitreous humour in proliferative diabetic retinopathy.

AIMS/HYPOTHESIS: Angiogenesis and inflammation characterise proliferative diabetic retinopathy (PDR), a major complication of diabetes mellitus. However, the impact of inflammation on the pathogenesis of PDR neovascularisation has not been elucidated. Here, we assessed the capacity of PDR vitreous fluid to induce pro-angiogenic/proinflammatory responses in endothelium and the contribution of the inflammation-related pattern recognition N-formyl peptide receptors (FPRs) in mediating these responses. METHODS: Pooled and individual pars plana vitrectomy-derived PDR vitreous fluid ('PDR vitreous') samples were assessed in endothelial cell proliferation, motility, sprouting and morphogenesis assays, and for the capacity to induce proinflammatory transcription factor activation, reactive oxygen species production, intercellular junction disruption and leucocyte-adhesion molecule upregulation in these cells. In vivo, the pro-angiogenic/proinflammatory activity of PDR vitreous was tested in murine Matrigel plug and chick embryo chorioallantoic membrane (CAM) assays. Finally, the FPR inhibitors Boc-Phe-Leu-Phe-Leu-Phe (Boc-FLFLF) and Ac-L-Arg-Aib-L-Arg-L-Cα(Me)Phe-NH2 tetrapeptide (UPARANT) were evaluated for their capacity to affect the biological responses elicited by PDR vitreous. RESULTS: PDR vitreous activates a pro-angiogenic/proinflammatory phenotype in endothelial cells. Accordingly, PDR vitreous triggers a potent angiogenic/inflammatory response in vivo. Notably, the different capacity of individual PDR vitreous samples to induce neovessel formation in the CAM correlates with their ability to recruit infiltrating CD45+ cells. Finally, the FPR inhibitor Boc-FLFLF and the novel FPR antagonist UPARANT inhibit neovessel formation and inflammatory responses triggered by PDR vitreous in the CAM assay. CONCLUSIONS/INTERPRETATION: This study provides evidence that inflammation mediates the angiogenic activity of PDR vitreous and paves the way for the development of FPR-targeting anti-inflammatory/anti-angiogenic approaches for PDR therapy.

Pharmacokinetic and Pharmacodynamic Properties of Anti-VEGF Drugs After Intravitreal Injection.

Subretinal neovascularization and pathologic ocular angiogenesis are common causes of progressive, irreversible impairment of central vision, and dramatically affect quality of life. Anti-vascular endothelial growth factor (anti-VEGF) therapy has improved the quality of life for many patients with age-related macular degeneration, diabetic retinopathy, and other ocular diseases involving neovascularization and edema. In these pathologies, the inhibition of intraocular VEGF is the only therapy that can preserve vision. Four anti-VEGF drugs are currently used to treat ocular neovascularization; pegaptanib, ranibizumab, and aflibercept have been approved for this condition, while bevacizumab can be used off-label. Anti-VEGF therapy is administered regularly for many months or years because its suspension or discontinuation may cause recurrence of neovascularization. On the other hand, VEGF is necessary for the survival of retinal and choroidal endothelial cells. Experimental studies in animal models have shown that local inhibition of VEGF causes thinning and atrophy of the choriocapillaris and degeneration of photoreceptors, primarily cones. These studies combined with clinical experience indicated that prolonged VEGF inhibition could impair retinal function. Moreover, anti-VEGF compounds can cross the blood-retina barrier, enter the systemic circulation, and inhibit serum VEGF. Since circulating VEGF protects blood vessel integrity, prolonged anti-VEGF treatment could induce thromboembolic adverse events from vascular causes such as heart attack and stroke, and even death. The ocular dosing regimen and systemic toxicity of anti-VEGF compounds are therefore central concerns. A better understanding of this topic requires knowledge of the metabolism, tissue distribution, and clearance of anti-VEGF compounds. This manuscript reviews the properties of anti-VEGF compounds following intravitreal administration.

Antiangiogenic Effectiveness of the Urokinase Receptor-Derived Peptide UPARANT in a Model of Oxygen-Induced Retinopathy.

PURPOSE: Pharmacologic control of neovascularization is a promising approach for the treatment of retinal angiogenesis. UPARANT, an inhibitor of the urokinase-type plasminogen activator receptor (uPAR), inhibits VEGF-driven angiogenesis in vitro and in vivo. This study investigates for the first time the effectiveness of UPARANT in counteracting pathologic neovascularization in the retina. METHODS: Murine retinal fragments and a mouse model of oxygen-induced retinopathy (OIR) were used. In mice with OIR, UPARANT-treated retinas were analyzed for avascular area and neovascular tuft formation. Levels of transcription and proangiogenic factors were determined. UPARANT effects on the blood-retinal barrier (BRB), visual function, retinal cytoarchitecture, and inflammatory markers were also assessed. Human umbilical vein endothelial cells (HUVECs) and chick embryo chorioallantoic membrane (CAM) in which angiogenesis was induced by the vitreous fluid from patients with proliferative diabetic retinopathy (PDR) were also used. RESULTS: UPARANT reduced VEGF-induced angiogenesis in retinal fragments. In mice with OIR, UPARANT decreased neovascular response, VEGF, and VEGF receptor-2 activity. Transcription factors regulating VEGF expression were also reduced. UPARANT restored BRB integrity, recovered visual loss, and reduced levels of inflammatory markers. Restored electroretinogram does not involve any rescue in the retinal cytoarchitecture. Finally, UPARANT blocked PDR vitreous fluid-induced angiogenesis in HUVEC and CAM assays. CONCLUSIONS: The finding that UPARANT is effective against neovascularization may help to establish uPAR as a target in the treatment of proliferative retinopathies. The potential application of UPARANT in retinal diseases is further supported by UPARANT capacity to counteract the angiogenic activity of PDR vitreous fluid.

Therapeutic Potential of Anti-Angiogenic Multitarget N,O-Sulfated E. Coli K5 Polysaccharide in Diabetic Retinopathy.

Vascular endothelial growth factor (VEGF) blockers have been developed for the treatment of proliferative diabetic retinopathy (PDR), the leading cause of visual impairments in the working-age population in the Western world. However, limitations to anti-VEGF therapies may exist because of the local production of other proangiogenic factors that may cause resistance to anti-VEGF interventions. Thus, novel therapeutic approaches targeting additional pathways are required. Here, we identified a sulfated derivative of the Escherichia coli polysaccharide K5 [K5-N,OS(H)] as a multitarget molecule highly effective in inhibiting VEGF-driven angiogenic responses in different in vitro, ex vivo, and in vivo assays, including a murine model of oxygen-induced retinopathy. Furthermore, K5-N,OS(H) binds a variety of heparin-binding angiogenic factors upregulated in PDR vitreous humor besides VEGF, thus inhibiting their biological activity. Finally, K5-N,OS(H) hampers the angiogenic activity exerted in vitro and in vivo by human vitreous fluid samples collected from patients with PDR. Together, the data provide compelling experimental evidence that K5-N,OS(H) represents an antiangiogenic multitarget molecule with potential implications for the therapy of pathologic neovessel formation in the retina of patients with PDR.

Relationship of wall-to-lumen ratio of retinal arterioles with clinic and 24-hour blood pressure.

Wall-to-lumen ratio of retinal arterioles might serve as an in vivo parameter of vascular damage. We analyzed the impact of brachial clinic blood pressure (BP), of central BP, and of 24-hour BP on wall-to-lumen ratio (WLR) of retinal arterioles. In 295 subjects (147 men; age range, 22-72 years; mean age, 54±7 years), WLR of retinal arterioles was assessed in vivo using scanning laser Doppler flowmetry. In addition, clinic and 24-hour BP values were measured. Central hemodynamics was assessed by pulse wave analysis. In treated patients with essential hypertension (n=100), a higher WLR (0.29±0.18 versus 0.23±0.13; P=0.009) was observed in comparison with normotensive individuals (n=119); no significant differences were observed between treated and untreated hypertensive patients (0.29±0.18 versus 0.28±0.18; P=0.7). WLR of retinal arterioles was significantly related to clinic systolic (r=0.18; P=0.002) and pulse pressure (r=0.20; P=0.001), to 24-hour systolic (r=0.25; P=0.0001) and pulse pressure (r=0.17; P=0.005), and to central systolic (r=0.16; P=0.006) and pulse pressure (r=0.18; P=0.002). Multiple regression analysis revealed that only mean systolic 24-hour BP was independently associated with an increased WLR of retinal arterioles. In this large group of hypertensive patients and normotensive individuals, 24-hour systolic BP seems to be the strongest determinant of increased WLR of retinal arterioles.

Effect of antihypertensive treatment on microvascular structure, central blood pressure and oxidative stress in patients with mild essential hypertension.

BACKGROUND: It has been previously demonstrated that dihydropyridine calcium channel blockers may possess antioxidant properties and might improve vascular structure. Combination treatment with an angiotensin-converting enzyme inhibitor may have additional advantages, compared with a thiazide diuretic, in this regard. The aim of the present study was, therefore, to investigate the effects of a short-term treatment with lercanidipine, and to compare two combination treatments: lercanidipine + enalapril vs. lercanidipine + hydrochlorothiazide on structural alterations in retinal arterioles, on skin capillary density and on large artery distensibility. PATIENTS AND METHODS: Twenty essential hypertensive patients were included in the study and treated for 4 weeks with lercanidipine 20 mg per day orally. Then they were treated for 6 months with lercanidipine + enalapril (n=10) or lercanidipine + hydrochlorothiazide (n=10) combinations. Investigations were performed in basal condition, after appropriate washout of previous treatments, after 4 weeks of lercanidipine monotherapy treatment, and at the end of the combination treatment. Non-invasive measurements of wall-to-lumen ratio (W/L) and other morphological parameters of retinal arterioles using scanning laser Doppler flowmetry were performed (Heidelberg Retina Flowmeter, Heidelberg Engineering). Capillary density was evaluated by capillaroscopy, whereas pulse wave velocity and central blood pressure were assessed by the Sphygmo-Cor device (AtCor Medical West Ryde, Australia). RESULTS: A significant improvement of W/L and of other indices of retinal artery structure was observed after treatment with lercanidipine alone, with a further improvement after treatment with lercanidipine + enalapril, whereas after treatment with lercanidipine + hydrochlorothiazide the improvement was no longer observed. A similar behaviour was observed for central SBP and DBP. Capillary density was increased only after treatment with lercanidipine + enalapril. CONCLUSION: Lercanidipine both in monotherapy and in combination with enalapril, was able to improve microvascular structure and to decrease central blood pressure, being thus a useful approach for both reducing blood pressure and improving vascular alterations in hypertension.

Predicting the risk of diabetic retinopathy in type 2 diabetic patients.

AIMS: Diabetic retinopathy (DR) is often asymptomatic even in its more advanced stages. Timely and repeated screening for DR avoids a late diagnosis of DR, but the high number of diabetic patients precludes a frequent screening; thus, the need for a method to identify patients at higher risk for DR becomes crucial. METHODS: A prospective analysis of 5034 type 2 diabetic patients followed from 1996 to 2007 and not affected by retinopathy at the time of the recruitment was performed. Patients were randomly divided (ratio 2:1) into two groups: the train data set and the test set (3327 and 1707 patients, respectively). Factors associated with the occurrence of DR were assessed by the Cox's proportional hazard model. RESULTS: Duration of diabetes, glycosylated hemoglobin, systolic blood Pressure, male gender, albuminuria and diabetes therapy other than diet were all significantly associated with the occurrence of DR. CONCLUSIONS: The nomogram could help in ranking the type 2 diabetic patients at higher risk to develop DR and thus with a need for more frequent ophthalmologic checks, without enhancing neither the time nor the costs.