Proliferative Diabetic Retinopathy Activity Research Articles

Intravitreal Injection for Diabetic Macular Edema as Adjunctive Therapy for Proliferative Diabetic Retinopathy: A Retrospective Study.

PurposeTo detect the impact of intravitreal injection (IVI) therapy with sole anti-vascular-endothelial-growth-factor (VEGF) or combined with steroids treating diabetic macular edema (DME) on activity of proliferative diabetic retinopathy (PDR) based on total number of panretinal photocoagulation (PRP) spots needed within 2 years.Patients and MethodsA retrospective study of 102 eyes with primary-onset PDR and minimum follow-up of 24 months divided into 2 groups: Group 1 (G1) 40 eyes received only PRP and did not develop DME. Group 2 (G2) 62 eyes received additional IVI-therapy due to concomitant DME, with anti-VEGF only (subgroup 2a, G2a) or in combination with steroids (subgroup 2b, G2b). Main outcomes: central macular thickness (CMT, µm), best-corrected visual acuity (BCVA, LogMAR) and total number of needed PRP spots and IVI after 24 months.ResultsCMT was significantly higher in G2 compared to G1, initially (p < 0.01) and after 24 months (p = 0.01). CMT was significantly higher in G2b compared to G2a, both initially (p = 0.01) and after 24 months (p < 0.01). BCVA was significantly higher in G1 compared to G2, initially and after 24 months (p = 0.01). BCVA was not significantly different between the two subgroups, initially (p = 0.54) and after 24 months (p = 0.29). The total number of PRP spots was significantly higher in G1 compared to G2 (p < 0.01) but not significantly different between the subgroups (p = 0.8).ConclusionRegardless of severity of concomitant DME, IVI with sole anti-VEGF or combined with steroids reduced the total number of PRP spots needed within 2 years significantly indicating a favorable effect on activity of PDR.

Retinal arteriolar calibre and venular fractal dimension predict progression of proliferative diabetic retinopathy 6 months after panretinal photocoagulation: a prospective, clinical interventional study

ObjectiveWe examined the hypothesis that baseline retinal vascular geometry in patients with proliferative diabetic retinopathy (PDR) predicts disease activity 6 months after panretinal photocoagulation (PRP).Methods and analysisWe included 47 eyes...

LASER PHOTOCOAGULATION FOR PROLIFERATIVE DIABETIC RETINOPATHY, SINGLE SPOT 532-nm vs MULTISPOT 577-nm: VERY SHORT TERM CLINICAL EFFICACY

ABSTRACT&#x0D; This study aimed to compare clinical efficacy of retinal laser photocoagulation using a 577-nm multi-spot laser with pulses of 20 ms versus conventional 532-nm single-spot laser treatment with pulses of 100 ms, on the same patient with proliferative diabetic retinopathy (PDR) during 6-weeks follow-up.&#x0D; We included 46 eyes of patients treated at the retina service of the Mexican Institute of Ophthalmology, Queretaro, Mexico. Pan-retinal photocoagulation (PRP) was performed on one eye (Group 1) using multi-spot PRP with the EasyRet® 577 diode laser (Quantel Medical, Cournon d’Auvergne, France). On the other eye (Group 2), laser treatment was performed by the conventional single spot method using the Oculight SL® 532 diode laser (IRIDEX Corporation, Mountain View, CA, The USA). The primary endpoint was absence of signs in which the disease was considered active at 6 weeks and the secondary outcomes included laser parameters, best-corrected visual acuity (BCVA), central macular thickness (CMT) at baseline, and 6 weeks and results of subjective pain analysis.&#x0D; There was no significant difference between both treatment groups regarding age, gender, BCVA or CMT at baseline. At 6 weeks, PDR activity was similar between the groups (47.8 % versus 56.5%; p =0.55). No significant difference in CMT and BCVA was observed between the groups throughout the study period. Patient-reported pain scores were similar between the groups (5.0 versus 5.8; p = 0.30). However, total time of procedure was significantly shorter in group 1 (12.9 minutes [min] versus 22.3 min; p &lt; 0.001). No major adverse events were identified&#x0D; We concluded that laser photocoagulation of the retina with the use of the multi-spot technology in patients with PDR has similar short-term efficacy to that of conventional single spot retinal photocoagulation. The multi-spot laser required less time to complete the procedure with more spots delivered to compensate its lower fluency, showing similar patient tolerance.&#x0D; &#x0D;

Swept-source optical coherence tomography angiography vitreo-retinal segmentation in proliferative diabetic retinopathy.

To identify a new cortical vitreous segmentation protocol for non invasive standardised investigation of Neovascularisation (NV) with detection of regression of NV activity in Proliferative Diabetic Retinopathy (PDR). Retrospective study. One hundred and eighty-six eyes of 93 consecutive diabetic patients (mean age: 52.6 ± 11.0 years) imaged using Topcon Triton® Swept-Source Optical Coherence Tomography Angiography (SS-OCTA) from June 2015 to January 2017. Scans were performed through the macula, optic disc and areas of possible NV in mid-peripheral retina using 6 × 6 mm and/or 9 × 9 mm raster-patterns in three segmentation protocols: Vitreo-Retinal (VRS), Outer-Vitreous (OVS) and Core-Vitreous Segmentation (CVS). Any suspicion of PDR was confirmed in all patients by Heidelberg® Widefield-Fundus-Fluorescein-Angiography (WF-FFA) and/or Optos® Ultra-WF-FFA (UWF-FFA). Inter-observer reproducibility of NV diagnosis and agreement between SS-OCTA and UWF-FFA were assessed. Primary outcome was the identification of an effective and reproducible segmentation protocol. Secondary outcome was the identification of NV regression after treatment. Sensitivity-specificity reached, respectively, the value of 100 to 100 in detecting NVD, and 96.6 to 100 in detecting NVE in compared areas. SS-OCTA was able to confirm absence of blood flow within the residual NV plexus when using VRS protocol in 30 eyes in which regression of NV with absence of leakage was documented on FFA. Three segmentation protocols (VRS, OVS and CVS) with different but complementary characteristics, allowed a reproducible and standardised investigation of NVD and NVE. The proposed new SS-OCTA cortical vitreous segmentation protocols may be of value when identifying and assessing NV-activity (VRS, OVS and CVS) or NV-regression (VRS) in PDR and therefore, response to therapy.

Elevated vitreous Lipocalin-2 levels of patients with proliferative diabetic retinopathy

BackgroundLipocalin-2 (LCN2) is a novel adipokine with potential roles in obesity, insulin resistance, and inflammation. This study aims to assess the concentrations of LCN2 and vascular endothelial growth factor (VEGF) expressed in the vitreous humors of patients with proliferative diabetic retinopathy (PDR).MethodsThe concentrations of LCN2 and VEGF were measured from the vitreous of 67 patients undergoing vitrectomy (20 controls and 47 PDR) via enzyme-linked immunosorbent assay (ELISA). Patients with non-ocular pathology that could elevate the LCN2 level in the vitreous were excluded. PDR activity and a history of panretinal photocoagulation were used for further grouping analysis.ResultsThe vitreous concentration of LCN2 was statistically significantly higher in the PDR group compared to the control group (63,522 (30,009) pg/ml versus 1663 (1191) pg/ml, respectively; P < 0.001). VEGF level was also significantly higher in the PDR group than in the control group (1038 (1326) pg/ml versus 9 pg/ml, respectively; P < 0.001). The mean vitreous LCN2 and VEGF levels in active PDR patients were significantly higher than that of the inactive PDR patients. The mean LCN2 concentration in vitreous humor was significantly lower in the 28 PDR patients with a history of complete PRP (37,304 (16,651) pg/mL) in comparison with 19 PDR patients without preperformed panretinal photocoagulation or with preperformed incomplete panretinal photocoagulation (79,796 (24,391) pg/mL). A significant correlation between the vitreous LCN2 level and VEGF level was found in patients with PDR (R = 0.34; P = 0.019).ConclusionsThis report shows a significant increase of LCN2 in the vitreous fluid of patients with PDR and present a significant correlation between LCN2 and VEGF, suggesting LCN2 might be involved in the pathogenesis of PDR.

Local and systemic production of 45 cytokines in complicated proliferative diabetic retinopaty

Diabetic retinopathy (DR) is multifactorial by its origin, involving many cytokines and growth factors. Studies of cytokine levels in biological fluids seem to be relevant for an in-depth understanding of the disease pathogenesis. The purpose of the work was a comparative analysis of 45 cytokines at systemic (blood serum (BS)) and local (vitreous humor (VH)) levels in the patients with complicated proliferative DR, showing various features of the clinical pattern. The content of cytokines was tested in 53 samples of BS and 32 samples of VH in 53 patients with type 1 and type 2 diabetes mellitus with severe proliferative DR. We used the multiplex analysis technique by means of xMAP platform and Luminex xPONENT 3.1 program using 45-plex sets (Procarta Plex «eBioscience», Austria). 25 cytokines were detected at significant amounts in BS test samples, and 27 cytokines were revealed in VH specimens. Sensitivity limits of the test system allowed to find significantly higher levels of 7 cytokines (IL-6, IL-8, IP-10, MCP-1, HGF, LIF and VEGF-A) in VH samples, than in the BS, thus indicating to their local intraocular production. Correlations between the contents of VEGF-A growth factor and amounts of cytokines, including those involved in inflammatory reactions, are shown in VH, thus presuming the interrelation of pathogenetic components, i.e., inflammation and neoangiogenesis. The features of intraocular cytokine content were determined for various manifestations of diabetic ocular changes. Hemophthalmus has been shown to be associated with increased IL-8 and IP-10; iris rubeosis, with increase in LIF; proliferative DR activity was associated with higher MCP-1 levels, and extremely severe changes were related to increase in IL-6 and EGF. Testing of cytokines in biological fluids is informative when studying the mechanisms of inflammation, neoangiogenesis, and protective responses in pathogenesis of diabetic retinopathy.

Interleukin-11 Overexpression and M2 Macrophage Density are Associated with Angiogenic Activity in Proliferative Diabetic Retinopathy

ABSTRACT Purpose To investigate the expression of IL-11 and its receptor IL-11Rα and to quantify density of CD163+ M2 macrophages in proliferative diabetic retinopathy (PDR). Methods Vitreous samples from 29 PDR and 19 nondiabetic patients, epiretinal fibrovascular membranes from 15 patients with PDR and Müller cells were studied by enzyme-linked immunosorbent assay, immunohistochemistry and Western blot analysis. Results We showed a significant increase in expression of IL-11, soluble(s) IL-11Rα, sCD163 and VEGF in vitreous samples from PDR patients compared to nondiabetic controls. Significant positive correlations were found between levels of VEGF and levels of IL-11 and sCD163. Significant positive correlations were found between microvessel density and number of blood vessels and stromal cells expressing IL-11, IL-11Rα and CD163 in PDR epiretinal membranes. The hypoxia mimetic agent cobalt chloride induced upregulation of IL-11 and IL-11Ra in cultured Müller cells. Conclusions IL-11/IL-11Rα signaling and CD163+ M2 macrophages might be involved in PDR angiogenesis.

Peripheral capillary non-perfusion in treatment-naïve proliferative diabetic retinopathy associates with postoperative disease activity 6 months after panretinal photocoagulation.

Background/aimsWith the perspective to provide individualised panretinal laser photocoagulation (PRP) for proliferative diabetic retinopathy (PDR), we evaluated if retinal peripheral capillary non-perfusion (PCNP) and oximetry, as non-invasive markers of retinal metabolism and function, could predict disease activity 6 months after PRP.MethodsWe performed a prospective, interventional study of patients with treatment-naïve PDR. Retinal oximetry and ultra-widefield fluorescein angiography were performed at baseline (BL) and three (3M) and 6 months (6M) after PRP by a navigated laser system. At 6M follow-up, patients were divided according to disease activity: active or inactive.ResultsWe included 33 eyes, and 69.6% were men. At BL, the median age and duration of diabetes (with IQRs) were 51.6±23.4 and 20.0±15.0 years. Haemoglobin A1c was 63.0±17.0 mmol/mol and blood pressure was 152±37/82±24 mm Hg. At BL and M6, patients with postoperative disease activity (30.3.%, n=10) had a larger area with PCNP than those with inactive PDR (BL: 51%–75% vs 26%–50%, p=0.03; 6M: 51%–75% vs 26%–50%, p=0.03). The area of PCNP did not change from BL to 6M in either group (inactive PDR: p=0.38, active PDR: p=0.87). Changes in retinal oxygen saturation were not found to be clinical relevant.ConclusionWe found the area of PCNP at all timepoints to be statistically larger in patients with active PDR 6 months after PRP treatment. Therefore, the area of PCNP, at baseline, may serve as a potential predictive marker for PDR activity after treatment.

Changes in retinal venular oxygen saturation predict activity of proliferative diabetic retinopathy 3 months after panretinal photocoagulation

Background/AimsProliferative diabetic retinopathy (PDR) is a severe blinding condition. We investigated whether retinal metabolism, measured by retinal oximetry, may predict PDR activity after panretinal laser photocoagulation (PRP).MethodsWe performed a prospective,...

Increased levels of alphaB-crystallin in vitreous fluid of patients with proliferative diabetic retinopathy and correlation with vascular endothelial growth factor.

AlphaB-crystallin has been shown to have angiogenic properties. The purpose of this study was to determine the levels of alphaB-crystallin in the vitreous fluid of patients with proliferative diabetic retinopathy and to confirm the association between the expression level of alphaB-crystallin and vascular endothelial growth factor. Vitreous samples were collected before vitrectomy from 46 eyes of 46 consecutive patients with proliferative diabetic retinopathy, and 19 patients without diabetes mellitus had vitrectomy for idiopathic macular hole. The concentrations of alphaB-crystallin and vascular endothelial growth factor were measured via enzyme-linked immunosorbent assay. The vitreous level (mean±SD) of alphaB-crystallin was significantly higher in patients with proliferative diabetic retinopathy (317.3±151.7ng/mL) than in control patients (idiopathic macular hole, 8.3±6.1ng/mL) (P<0.0001). The vitreous concentration of vascular endothelial growth factor was also significantly higher in patients with proliferative diabetic retinopathy (860.1±566.4pg/mL) than in control patients (9pg/mL) (P<0.0001). Meanwhile, both the expression levels of alphaB-crystallin and vascular endothelial growth factor were significantly higher in eyes with active proliferative diabetic retinopathy than in those with inactive proliferative diabetic retinopathy. Also, the vitreous concentration of alphaB-crystallin correlated significantly with that of vascular endothelial growth factor in vitreous fluid of proliferative diabetic retinopathy ([correlation coefficient], R=0.78, P<0.001). These results suggest a significant increase of alphaB-crystallin in the vitreous fluid of patients with proliferative diabetic retinopathy and present a crucial association between alphaB-crystallin and vascular endothelial growth factor with angiogenic activity in proliferative diabetic retinopathy.

Vitreous levels of placental growth factor correlate with activity of proliferative diabetic retinopathy and are not influenced by bevacizumab treatment.

PurposePlacental growth factor (PlGF) is a member of the VEGF family that plays an important role in experimental models of diabetic retinopathy and retinal neovascularization. We aimed to investigate whether vitreous levels of PlGF correlated with proliferative diabetic retinopathy (PDR) status, VEGF levels, and bevacizumab treatment. We also analysed PDR membranes to confirm the presence of the PlGF receptor, FLT1, in endothelial cells.MethodsThis was a case-control study: undiluted vitreous fluid samples were obtained from 28 active PDR patients without preoperative bevacizumab treatment, 21 active PDR patients with preoperative bevacizumab treatment, 18 inactive PDR patients, and 21 control patients. PlGF and VEGF levels in samples were determined by enzyme-linked immunosorbent assay. Immunohistochemistry for FLT1 was performed on human PDR membranes.ResultsCompared to control, vitreous PlGF levels were higher in both active PDR without bevacizumab (P<0.0001) and with bevacizumab (P<0.0001). There was no significant difference in PlGF between active PDR patients without and with bevacizumab (P=0.56). Compared to active PDR, PlGF levels were significantly reduced in inactive PDR (P=0.004). PlGF levels were highly correlated with VEGF levels in active PDR. VEGFR1 was expressed in endothelial cells in human PDR membranes.ConclusionThe strong correlation of PlGF levels with PDR disease status and expression of FLT1 in human PDR membranes suggest that PlGF has a pathogenic role in proliferative diabetic retinopathy. Therapeutic targeting of PlGF with agents like aflibercept may be beneficial.

Receptor-associated prorenin system contributes to development of inflammation and angiogenesis in proliferative diabetic retinopathy.

The renin-angiotensin system (RAS) plays a potential role in the development of end-organ damage, and tissue RAS activation has been suggested as a risk factor of several diseases including diabetes. So far, using animal disease models, we have shown molecular mechanisms, in which tissue RAS stimulates retinal angiogenesis, and the critical roles of (pro)renin receptor [(P)RR] in retinal RAS activation and its concurrent intracellular signal transduction, referred to as the receptor-associated prorenin system (RAPS). Moreover, we recently reported that the protein levels of prorenin and soluble (P)RR increased in the vitreous fluids obtained from patients with proliferative diabetic retinopathy (PDR), suggesting the association of (P)RR with vascular endothelial growth factor (VEGF)-driven angiogenic activity in human PDR, and also showed a close relationship between the vitreous renin activity and VEGF-induced pathogenesis of diabetic retinopathy. Our data using animal disease models and human clinical samples suggest that both vitreous RAS and retinal RAPS play critical roles in the molecular pathogenesis of diabetic retinopathy.

The role of tryptase and anti-type II collagen antibodies in the pathogenesis of idiopathic epiretinal membranes.

PurposeTo investigate the pathogenesis of idiopathic epiretinal membrane (ERM) from a biochemical perspective, the relationships between ERM and tryptase activity, a serine protease, and the levels of anti-type II collagen (anti-IIC) antibodies in the serum.Patients and methodsVitreous samples for measurement of tryptase activity were obtained from 54 eyes of 54 patients who underwent a vitrectomy for vitreoretinal disease, ie, 14 eyes of 14 patients with idiopathic macular hole, 14 eyes of 14 patients with proliferative diabetic retinopathy (PDR), 13 eyes of 13 patients with ERM, and 13 eyes of 13 patients with rhegmatogenous retinal detachment (RRD). Tryptase activity was measured by spectrophotometry. Anti-IIC antibodies were measured in the serum obtained from 17 patients with ERM, eight patients who underwent cataract surgery, 12 patients with PDR, and nine patients with RRD. In these 46 patients, the anti-IIC antibodies were measured using a Human/Monkey Anti-Type I and Type II Collagen IgG Assay Kit.ResultsVitreal tryptase activity (mean ± standard deviation [SD]) in macular hole, PDR, ERM, and RRD was 0.0146±0.0053, 0.0018±0.0018, 0.0166±0.0046, and 0.0117±0.0029 mU/mg protein, respectively. Vitreal tryptase activity was significantly higher in macular hole and ERM than in PDR and RRD (P<0.05, Fisher’s protected least significant difference). The serum levels of anti-IIC immunoglobulin G (IgG) antibody (mean ± SD) in ERM, cataract surgery, PDR, and RRD were 58.222±30.986, 34.890±18.165, 55.760±26.008, and 35.453±12.769 units/mL, respectively. The serum levels of anti-IIC IgG antibody were significantly higher in ERM and PDR than in cataract surgery and RRD (P<0.05, Fisher’s protected least significant difference, two-sided).ConclusionIn the pathogenesis of ERM, increased vitreal tryptase activity may be involved in tissue fibrosis, and elevated serum anti-IIC antibodies may lead to an immune response at the vitreoretinal interface, thus resulting in membrane formation.

Epiretinal membrane inflammatory cell density might reflect the activity of proliferative diabetic retinopathy.

Diabetic retinopathy (DR) has features of chronic low-grade inflammation. The purpose of our study was to investigate whether the presence of inflammatory cells in fibrovascular membranes (FVMs) from patients with proliferative diabetic retinopathy (PDR) is associated with the activity of PDR and visual acuity improvement after vitreoretinal surgery. Forty FVMs from 40 patients with PDR were obtained during vitrectomy, prepared by using the agar sandwich method, and examined using light microscope and immunohistochemistry methods to define the presence and density of inflammatory cells: CD45+ cells (leukocytes), CD4+ cells (T helper lymphocytes), CD8+ cells (T cytotoxic lymphocytes), CD19+ cells (B lymphocytes), and CD14+ cells (monocytes/macrophages). For each FVM, the inflammatory cell density defined as numerical areal density was calculated. The number of vessels was defined as the volume density of vessels. Among 40 patients with PDR, 33 patients had active PDR and 7 quiescent PDR. Significant differences in cell densities for CD4+, CD8+, and CD19+ cells were observed between patients with active and quiescent PDR. B lymphocytes were present in membranes of active PDR only. No correlation was observed between numerical areal density of inflammatory cells and the volume density of vessels. No association was found between visual acuity improvement after surgery and cell densities. Lymphocyte infiltration of FVMs might be associated with the activity of retinopathy but not with visual acuity improvement after surgery.

Increased intravitreous interleukin-18 correlated to vascular endothelial growth factor in patients with active proliferative diabetic retinopathy

To determine the intravitreous levels of interleukin-18 (IL-18) and vascular endothelial growth factor (VEGF) in patients with proliferative diabetic retinopathy (PDR) and to ascertain their association with PDR activity. Thirty eyes of 30 diabetic patients with PDR were divided into two groups (active PDR, n = 17; quiescent PDR, n = 13). Fifteen eyes of 15 non-diabetic patients (macular hole, n = 9; epiretinal membrane, n = 6) served as controls. All vitreous fluid samples were obtained during vitrectomy. IL-18 and VEGF were measured by enzyme-linked immunosorbent assay. Serum glycosylated hemoglobin as well as the basic demographic data was documented. Both IL-18 and VEGF levels were higher in patients with PDR than control (P < 0 .01 and P < 0 .01, respectively). Both IL-18 and VEGF in active PDR were higher than those in quiescent PDR (P = 0.048 and P = 0.03, respectively). A significant positive correlation (Spearman rank correlation coefficient (r s) = 0.502, P = 0.005) between IL-18 and VEGF was observed in all PDR patients but not in the control. The correlation between VEGF and IL-18 was even stronger in the subgroup of active PDR (r s = 0.684; P = 0.002), whereas no significant correlation was found in the subgroup of quiescent PDR (r s = 0.049; P = 0.873). Both intravitreous IL-18 and VEGF were elevated in patients with PDR, which were closely correlated in active PDR. IL-18 may contribute to retinal angiogenesis by acting together with or via VEGF, and become the potential therapeutic target for treatment of PDR.

Association of hyperglycemia mediated increased advanced glycation and erythrocyte antioxidant enzyme activity in different stages of diabetic retinopathy

AimThis study aimed to evaluate whether hyperglycemia mediated increased formation of advanced glycation end products (AGEs) was associated with erythrocyte antioxidant enzyme activity in subjects with different stages of diabetic retinopathy (DR). MethodsSerum level of AGEs was determined by enzyme linked immunosorbent assay. Erythrocyte superoxide dismutase (SOD), glutathione reductase (GR) and catalase activity were estimated by enzymatic reaction based spectrophotometric assay in patients with type 2 diabetes with proliferative diabetic retinopathy (PDR), non-proliferative diabetic retinopathy (NPDR) and no retinopathy (DNR) and also in healthy non-diabetic controls (HC). ResultErythrocyte SOD and GR activity was significantly lower among NPDR (p=0.024, 0.0017, respectively) and PDR (p=0.0003, 0.0001, respectively) subjects compared with DNR individuals. A significant inverse correlation was observed between serum AGEs and erythrocyte SOD or GR activity in DNR (p=0.0019; r=−0.3033, p=0.0021; r=−0.3015, respectively), NPDR (p=0.0001; r=−0.4602, p=0.0003; r=−0.4161, respectively), and PDR (p<0.0001; r=−0.6753, p<0.0001; r=−0.5854, respectively) individuals. ConclusionPoor glycemia may be the key factor enhancing AGE formation, which may be associated with lower erythrocyte SOD and GR activity along with increased catalase activity in DR.

(Pro)renin receptor is associated with angiogenic activity in proliferative diabetic retinopathy

Aims/hypothesis The renin–angiotensin system (RAS) potentially has a role in the development of end-organ damage, and tissue RAS activation has been suggested as a risk factor for diabetic retinopathy. We have recently shown significant involvement of (pro)renin receptor ([P]RR) in retinal inflammation in a rodent model of early diabetes. In this study we aim to elucidate the (P)RR-associated pathogenesis of fibrovascular proliferation, a late-stage angiogenic complication in human diabetic retinopathy.

A flow cytometric analysis of vitreous inflammatory cells in patients with proliferative diabetic retinopathy.

The purpose of this study was to investigate inflammatory cells in vitreous from patients with proliferative diabetic retinopathy (PDR) using flow cytometric analysis. Twenty-eight patients with PDR requiring vitrectomy because of macular traction or tractional retinal detachment were enrolled in the study (n = 28), and 6 patients with macular hole (MH) formed the control group. Samples of vitreous and peripheral venous blood were obtained at the beginning of vitrectomy. T lymphocytes were found in vitreous from patients with PDR, and CD4/CD8 ratio was higher in vitreous (median 4.3) compared to blood (median 1.9; P = 0.003). No B lymphocytes were detected in vitreous. The percentage of histiocytes/macrophages was significantly higher in vitreous (median 62.1) in comparison with blood (median 5.5; P < 0.0001). No lymphocytes were detected in vitreous of the control group. There were more T lymphocytes in vitreous from patients with active PDR. No association between cells in the vitreous and visual acuity improvement after surgery was found. In conclusion, T lymphocytes are found in vitreous from patients with PDR and reflect the activity of PDR but do not seem to predict visual prognosis. Higher CD4/CD8 ratio in vitreous compared to blood from patients with PDR is consistent with local inflammatory response in PDR.

(Pro)renin receptor is associated with angiogenic activity in proliferative diabetic retinopathy

The renin-angiotensin system (RAS) potentially has a role in the development of end-organ damage, and tissue RAS activation has been suggested as a risk factor for diabetic retinopathy. We have recently shown significant involvement of (pro)renin receptor ([P]RR) in retinal inflammation in a rodent model of early diabetes. In this study we aim to elucidate the (P)RR-associated pathogenesis of fibrovascular proliferation, a late-stage angiogenic complication in human diabetic retinopathy. Vitreous fluids from 23 eyes of patients with proliferative diabetic retinopathy (PDR) and 16 eyes of controls with non-diabetic, idiopathic macular diseases (macular hole and epiretinal membrane) were collected. Protein levels of soluble (P)RR were measured by ELISA, and immunofluorescence was performed to assess the localisation of (P)RR and related molecules in fibrovascular tissues from PDR eyes. (P)RR immunoreactivity was detected in neovascular endothelial cells, colocalised with prorenin, phosphorylated extracellular signal-regulated kinase (ERK) and vascular endothelial growth factor (VEGF). Prorenin application to human retinal microvascular endothelial cells significantly upregulated mRNA expression of VEGF, especially the VEGF165 isoform, which was abolished by (P)RR or ERK signalling blockade. Proteases known to cleave (P)RR, including furin, were positive in endothelial cells in fibrovascular tissues. Protein levels of soluble (P)RR in vitreous fluids were higher in PDR eyes than in non-diabetic control eyes, and correlated significantly with vitreous prorenin and VEGF levels and the vascular density of fibrovascular tissues. Our data using human samples provide the first evidence that (P)RR is associated with angiogenic activity in PDR.

Succinate Increases in the Vitreous Fluid of Patients With Active Proliferative Diabetic Retinopathy

To examine vitreous succinate levels from proliferative diabetic retinopathy (PDR) patients and ascertain their association with PDR activity. Comparative case series. A total of 81 eyes of 72 PDR patients were divided into active PDR (22 eyes), quiescent PDR (21 eyes), and active PDR with intravitreal bevacizumab injection (38 eyes). Twenty epiretinal membrane (ERM) patients (21 eyes) served as controls. Mean vitreous succinate levels were 1.27 μM in ERM and 2.20 μM in PDR, with the differences statistically significant (P = .03). When comparing mean vitreous succinate levels (active PDR: 3.32 μM; quiescent PDR: 1.02 μM; active PDR with intravitreal bevacizumab injection: 1.20 μM), significant differences were found between active and quiescent PDR (P < .01) and between active PDR and active PDR with intravitreal bevacizumab injection (P < .01). Even though succinate levels were low, retinopathy activities were very high in patients with active PDR with intravitreal bevacizumab injection. Mean vitreous vascular endothelial growth factor (VEGF) levels (active PDR: 1696 pg/mL; quiescent PDR: 110 pg/mL; active PDR with intravitreal bevacizumab injection: n.d.) were similar to previous reports. Mean vitreous erythropoietin levels (active PDR: 703 mIU/mL; quiescent PDR: 305 mIU/mL; active PDR with intravitreal bevacizumab injection: 1562 mIU/mL) suggested very high retinopathy activities in patients with active PDR with intravitreal bevacizumab injection. Succinate, like VEGF, may be an angiogenic factor that is induced by ischemia in PDR. Although succinate is reported to promote VEGF expression, VEGF inhibition decreases succinate. Thus, VEGF, via a positive feedback mechanism, may regulate succinate.