Intravitreal bevacizumab increases intraocular interleukin-6 levels at 1day after injection in patients with proliferative diabetic retinopathy

Changes in aqueous and vitreous inflammatory cytokine levels in proliferative diabetic retinopathy: a systematic review and meta-analysis

BACKGROUND

Diabetic retinopathy is a major complication of diabetes mellitus, where in its most advanced form ischemic changes lead to the development of retinal neovascularization, termed proliferative diabetic retinopathy (PDR). While the development of PDR is often associated with angiogenic and inflammatory cytokines, studies differ on which cytokines are implicated in disease pathogenesis and on the strength of these associations. We therefore conducted a systematic review and meta-analysis to quantitatively assess the existing body of data on intraocular cytokines as biomarkers in PDR.

METHODS

A comprehensive search of the literature without year limitation was conducted to January 18, 2021, which identified 341 studies assessing vitreous or aqueous cytokine levels in PDR, accounting for 10379 eyes with PDR and 6269 eyes from healthy controls. Effect sizes were calculated as standardized mean differences (SMD) of cytokine concentrations between PDR and control patients.

RESULTS

Concentrations (SMD, 95% confidence interval, and p-value) of aqueous IL-1β, IL-6, IL-8, MCP-1, TNF-α, and VEGF, and vitreous IL-2, IL-4, IL-6, IL-8, angiopoietin-2, eotaxin, erythropoietin, GM-CSF, GRO, HMGB-1, IFN-γ, IGF, IP-10, MCP-1, MIP-1, MMP-9, PDGF-AA, PlGF, sCD40L, SDF-1, sICAM-1, sVEGFR, TIMP, TNF-α, and VEGF were significantly higher in patients with PDR when compared to healthy nondiabetic controls. For all other cytokines no differences, failed sensitivity analyses or insufficient data were found.

CONCLUSIONS

This extensive list of cytokines speaks to the complexity of PDR pathogenesis, and informs future investigations into disease pathogenesis, prognosis, and management.

Downregulation of angiogenic factors in aqueous humor associated with less intraoperative bleeding in PDR patients with NVG receiving conbercept: a randomized controlled trial

BACKGROUND

To analyze the level changes of 28 cytokines in aqueous humor of patients with proliferative diabetic retinopathy (PDR) coexisting neovascular glaucoma (NVG) after intravitreal injection of conbercept (IVC), and to investigate whether these cytokines are associated with intraoperative bleeding (IOB).

METHODS

Totally 34 eyes with NVG secondary to PDR were enrolled. Patients were randomized into two groups, and all of them underwent 25-gauge pars plana vitrectomy (PPV) combined with trabeculectomy. Group I, 18 eyes received IVC 3 days before PPV, and 100 µL aqueous humor was collected at the time of IVC pretreatment and 3 days later at the beginning of PPV respectively. Group II, 16 eyes received IVC after PPV, and 100 µL aqueous humor was collected only at the beginning of PPV. Aqueous humor from 19 eyes with age-matched cataract patients served as controls. Luminex bead-based multiplex array was used to measure the levels of 28 cytokines in aqueous humor. The baseline cytokine levels were compared among the three groups. All NVG patients were divided into IOB and non-bleeding (INB) groups. The cytokine levels of aqueous humor at the beginning of PPV were compared between group I and II, also between IOB and INB groups. IOB in NVG patients was graded according to vitreous bleeding amount. The correlation between cytokine levels and the grades of IOB were analyzed.

RESULTS

Compared with controls, the baseline levels of 18 cytokines associated with inflammation and angiogenesis showed significantly increased in group I and group II (all, P < 0.0167). The IOB rate as well as the levels of IL-4, IL-22, Ang-2, PLGF and VEGF-A in group I were significantly lower than in group II (all, P < 0.05). The levels of IL-4, IL-22, Ang-2, PLGF and VEGF-A were significantly lower in INB group than in IOB group (all, P < 0.05). The levels of IL-4, Ang-2, PLGF and VEGF-A were positively correlated with the grades of IOB in NVG patients (all, r_s > 0.4, P < 0.05).

CONCLUSIONS

IVC 3 days before PPV combined with trabeculectomy reduces IOB in NVG patients, in which the downregulation of IL-4, Ang-2, PLGF and VEGF-A after IVC may be an underlying mechanism.

TRIAL REGISTRATION

ChiCTR2100048118 , retrospectively registered on 2 July 2021.

Vitreous Inflammatory Cytokines and Chemokines, Not Altered After Preoperative Adjunctive Conbercept Injection, but Associated With Early Postoperative Macular Edema in Patients With Proliferative Diabetic Retinopathy

Purpose

To investigate the influence of preoperative adjunctive anti-VEGF drug (Conbercept) on vitreous inflammatory cytokines and chemokines profiles and whether those cytokines were associated with early macular edema (ME) after surgery for patients with proliferative diabetic retinopathy (PDR).

Methods

In this post hoc analysis of the CONCEPT clinical trial, subjects with PDR underwent vitrectomy were included and vitreous samples were collected at the start of vitrectomy. Levels of vitreous VEGF, 17 inflammatory cytokines, and 11 chemokines were measured using Luminex multiplex technology. Subjects were then divided into groups based on with (Pre-IV) or without (No-Pre-IV) preoperative intravitreous injection of Conbercept; with or without early ME after surgery.

Results

There was no difference between Pre-IV (13/30) and No-Pre-IV (7/29) concerning the ratio of patients with early ME (p = 0.17). After preoperative intravitreous injection of Conbercept, VEGF level dramatically decreased (p = 0.001), TNF-α (p = 0.002), and IP-10 (p = 0.018) increased in Pre-IV group. In patients with early ME after surgery, however, a number of cytokines increased, including IL-1β (p = 0.008), IL-2 (p = 0.023), IL-4 (p = 0.030), IL-9 (p = 0.02), IL-10 (p = 0.002), IL-12 (p = 0.001), IL-13 (p = 0.031), IL-17A (p = 0.008), TNF-α (p = 0.012), CXCL9 (p = 0.023), G-CSF (p = 0.019), MCP-1 (p = 0.048), and RANTES (p = 0.016).

Conclusion

We found the preoperative adjunctive Conbercept injection has limited influence on the levels of vitreous inflammatory cytokines and chemokines in PDR. The elevated levels of a series of cytokines might be associated with early inflammation after vitrectomy, which may lead to postoperative ME.

Reduced Expression of Erythropoietin After Intravitreal Ranibizumab in Proliferative Diabetic Retinopathy Patients-Retrospective Interventional Study

Purpose: To evaluate the expressions of erythropoietin (EPO) and vascular endothelial growth factor (VEGF) in the vitreous and fibrovascular membranes (FVMs) of proliferative diabetic retinopathy (PDR) after the intravitreal injection of ranibizumab (IVR) and further explore the relationship between EPO and VEGF. Method: The concentrations of EPO and VEGF levels in the vitreous fluid were measured in 35 patients (24 PDR and 11 non-diabetic patients) using enzyme-linked immunosorbent assay. The patients were divided into three groups: PDR with IVR (IVR group) before par plana vitrectomy (n = 10), PDR without IVR (Non-IVR group) (n = 14) and a control group [macular holes (MHs) or epiretinal membranes (ERM), n = 11]. Fluorescence immunostaining was performed to examine the expressions of VEGF, EPO and CD 105 in the excised epiretinal membranes. Result: The PDR eyes of Non-IVR group had the highest vitreous VEGF and EPO levels (836.30 ± 899.50 pg/ml, 99.29 ± 27.77 mIU/ml, respectively) compared to the control group (10.98 ± 0.98 pg/ml and 18.96 ± 13.30 mIU/ml/ml). Both the VEGF and EPO levels in the IVR group (13.22 ± 2.72 pg/ml and 68.57 ± 41.47 mIU/ml) were significantly lower than the Non-IVR group (P = 0.004 and P = 0.04, respectively). Furthermore, no significant difference was observed for VEGF levels between the control and IVR groups (10.9 ± 0.98 pg/ml and 13.22 ± 2.72 pg/ml, respectively, P = 0.9). Yet the EPO level in the IVR group was significantly higher than that in the Non-diabetic group (68.57 ± 41.47 pg/ml and 18.96 ± 13.30 pg/ml, respectively, P = 0.001). The expressions of EPO, VEGF, and CD105 were significantly reduced in fluorescence immunostaining of FVMs in the IVR group compared with the Non-IVR group. The receiver operating characteristic (ROC) curve of the EPO and VEGF levels were 0.951 and 0.938 in the PDR group. Conclusion: Both of the VEGF and EPO level were significantly increased in PDR patients, which have equal diagnostic value in the prediction of PDR. IVR could reduce the EPO level, but not enough to the normal level.

Aqueous humor monocyte chemoattractant protein-1 predicted long-term visual outcome of proliferative diabetic retinopathy undergone intravitreal injection of bevacizumab and vitrectomy

PURPOSE

We aim to investigate the risk factors associated with the prognosis of proliferative diabetic retinopathy (PDR) after a sequential treatment of intravitreal injection of bevacizumab (IVB) and pars plana vitrectomy (PPV).

METHODS

In this cohort study, 63 eyes from 55 patients (21 females) diagnosed with PDR, who needed PPV for non-clearing vitreous hemorrhage or fibrovascular membrane proliferation were enrolled. All the eyes underwent IVB followed by PPV. Anterior chamber tap was performed at the beginning of both procedures to evaluate the concentration of vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-8, and monocyte chemoattractant protein (MCP)-1.

RESULTS

Forty-seven patients (54 eyes) were followed over six months, averaging 12±5 (6-19) months. The concentration of VEGF significantly decreased after IVB (P<0.001), while other cytokines did not change significantly. The aqueous humor level of IL-8 after IVB (R = 0.378, P = 0.033), MCP-1 before (R = 0.368, P = 0.021) and after (R = 0.368, P = 0.038) IVB, and combined phacoemulsification (R = 0.293, P = 0.032) was correlated with the logMAR visual acuity at the last follow-up. Multivariate analysis showed that MCP-1 was the predictor for a worse visual outcome (B = 0.108, 95% CI 0.013-0.202; P = 0.027).

CONCLUSIONS

MCP-1 was a predictor for the unfavorable visual outcome of PDR after IVB pretreatment and PPV.

Differential effects of risuteganib and bevacizumab on AMD cybrid cells

PURPOSE

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) treatments are currently used to treat wet age-related macular degeneration (AMD), diabetic retinopathy, and macular edema. Chronic, repetitive treatments with anti-VEGF may have unintended consequences beyond the inhibition of angiogenesis. Most recently, clinical trials have been conducted with risuteganib (RSG, Luminate®), which is anti-angiogenic and has neuroprotective and anti-inflammatory properties. Mitochondrial damage and dysfunction play a major role in development of AMD. Transmitochondrial cybrids are cell lines established by fusing human retinal pigment epithelial (RPE) cells that are Rho0 (lacking mtDNA) with platelets isolated from AMD subjects or age-matched normal subjects. Cybrid cell lines have identical nuclei but mitochondria from different subjects, enabling investigation of the functional consequences of damaged AMD mitochondria. The present study compares the responses of AMD cybrids treated with bevacizumab (Bmab, Avastin®) versus risuteganib (RSG, Luminate®).

METHODS

Cybrids were created by fusing mtDNA depleted ARPE-19 cells with platelets from AMD or age-matched normal patients. AMD (n = 5) and normal (n = 3) cybrids were treated for 48 h with or without 1x clinical dose of 1.25 mg/50 μl (25,000 μg/ml) of Bmab or 1.0 mg/50 μl (20,000 μg/ml) of RSG. Cultures were analyzed for levels of cleaved caspase 3/7 and NucLight Rapid Red staining (IncuCyte® Live Cell Imager), mitochondrial membrane potential (ΔΨm, JC1 assay) or reactive oxygen species (ROS, H2DCFDA assay). Expression levels of genes related to the following pathways were analyzed with qRT-PCR: Apoptosis (BAX, BCL2L13, CASP-3, -7, -9); angiogenesis (VEGFA, HIF1α, PDGF); integrins (ITGB-1, -3, -5, ITGA-3, -5, -V); mitochondrial biogenesis (PGC1α, POLG); oxidative stress (SOD2, GPX3, NOX4); inflammation (IL-6, -18, -1β, IFN-β1); and signaling (P3KCA, PI3KR1). Statistical analyses were performed using GraphPad Prism software.

RESULTS

The untreated AMD cybrids had significantly higher levels of cleaved caspase 3/7 compared to the untreated normal cybrids. The Bmab-treated AMD cybrids showed elevated levels of cleaved caspase 3/7 compared to untreated AMD or RSG-treated AMD cybrids. The Bmab-treated cybrids had lower ΔΨm compared to untreated AMD or RSG-treated AMD cybrids. The ROS levels were not changed with Bmab or RSG treatment. Results showed that Bmab-treated cybrids had higher expression levels of inflammatory (IL-6, IL1-β), oxidative stress (NOX4) and angiogenesis (VEGFA) genes compared to untreated AMD, while RSG-treated cybrids had lower expression levels of apoptosis (BAX), angiogenesis (VEGFA) and integrin (ITGB1) genes.

CONCLUSIONS

These data suggest that the mechanism(s) of action of RSG, an integrin regulator, and Bmab, a recombinant monoclonal antibody, affect the AMD RPE cybrid cells differently, with the former having more anti-apoptosis properties, which may be desirable in treating degenerative ocular diseases.

Updates on the Management of Ocular Vasculopathies with VEGF Inhibitor Conbercept

Purpose: To provide a detailed review on the therapeutic efficacy of conbercept for the management of ocular vasculopathies. Methods: A comprehensive literature search of various electronic databases was performed. Results: Ocular vasculopathy is one of the major causes of visual impairment and blindness which includes a range of disorders. Vascular endothelial growth factor (VEGF) regulates angiogenesis, enhances vascular permeability, and drives the formation of neovascularization. Anti-VEGF therapy has been shown to prevent vision loss or potentially improve vision in patients with exudative or neovascular retinal disease. The most recent anti-VEGF drug in China is conbercept. In the USA and Europe, bevacizumab is the most recently approved anti-VEGF agent. Conclusions: Conbercept serves as another anti-VEGF option for patients with neovascular AMD and other retinal vascular disorders. There have not been many clinical trials that study conbercept as compared with other currently available anti-VEGF drugs. There is a need for large-scale, well-designed, randomized clinical trials to ensure its long-term safety and efficacy and to determine if it has any advantages over other anti-VEGF agents.

Effect of Alternate Treatment with Intravitreal Anti-Vascular Endothelial Growth Factor and Steroid for Treatment-Naive Diabetic Macular Edema in a Real-Life Setting

Purpose: To assess if alternate treatment with intravitreal anti-vascular endothelial growth factor (VEGF) and corticosteroid injections can improve visual and anatomical outcomes of treatment-naive diabetic macular edema (DME) in a real-life setting. Methods: This single-center retrospective study included 71 treatment-naive DME eyes that received intravitreal anti-VEGF monotherapy (48 eyes, anti-VEGF group) or were alternately treated with intravitreal anti-VEGF and corticosteroid injections (23 eyes, alternate group). Results: During the 2-year follow-up period, the anti-VEGF group received an average of 5.7 injections, while the alternate group received 6.4 injections (P = 0.085). The alternate group demonstrated a 0.10 logMAR gain in visual acuity; the anti-VEGF group showed a 0.05 logMAR loss (P = 0.040). The alternate group achieved an 87.7-μm reduction in central macular thickness; the anti-VEGF group achieved a 57.0-μm reduction (P = 0.676). There was a visual loss ≥0.20 logMAR in 8.7% of the eyes in the alternate group and 33.3% of the eyes in the anti-VEGF group (P = 0.039). Cataract surgery was performed in 8.9% of the phakic eyes in the anti-VEGF group and 56.3% of the phakic eyes in the alternate group (P < 0.001). Conclusions: Alternate treatment with intravitreal anti-VEGF and corticosteroid injections demonstrated a more favorable visual outcome in treatment-naive DME eyes compared to intravitreal anti-VEGF monotherapy.

MicroRNA-27a protects retinal pigment epithelial cells under high glucose conditions by targeting TLR4

The present study aimed to investigate whether microRNA-27a (miRNA27a) is associated with the pathogenesis of diabetic retinopathy, and to elucidate the underlying molecular mechanism of any potential association. In retinal pigment epithelial (RPE) cells treated with high glucose, miRNA27a expression, determined by reverse transcription-quantitative polymerase chain reaction analysis, was decreased. Caspase-3/9 activity and B-cell lymphoma 2-associated X (Bax) protein expression was increased in RPE cells subjected to high glucose. Inhibition of miRNA27a suppressed the viability, and increased the caspase-3/9 activity and Bax protein expression of RPE cells treated with high glucose. Inhibition of miRNA27a expression also increased the expression of interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α and Toll-like receptor 4 (TLR4) in RPE cells treated with high glucose. Treatment with immunostimulatory (is)RNA directed against TLR4 was observed to inhibit caspase-3/9 activity, decrease the expression of TLR4, Bax, IL-6, IL-1β and TNF-α, and increase the viability of RPE cells subjected to high glucose following the inhibition miRNA27a. In conclusion, the results of the present study suggest that miRNA27a protects RPE cells subjected to high glucose via inhibiting inflammation and apoptosis through targeting TLR4.

Antiangiogenic activity of PLGA-Lupeol implants for potential intravitreal applications

Uncontrolled angiogenesis is directly associated with ocular diseases such as macular degeneration and diabetic retinopathy. Implantable polymeric drug delivery systems have been proposed for intravitreal applications and in the present work, we evaluated the antiangiogenic potential of PLGA ocular implants loaded with the triterpene lupeol using in vitro and in vivo models. The drug/polymer physiochemical properties of the lupeol-loaded PLGA were validated as functionally similar using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Interestingly, in an in vitro culture system, lupeol (100μg/mL and 250μg/mL) was capable to inhibited the proliferation as well as the migration of Human Umbilical Vein Endothelial Cells (HUVEC), without interfering in cell viability, promoting a significant reduction in the percentage of vessels (39.41% and 44.12%, respectively), compared with the control group. In vivo test, by using the chorioallantoic membrane (CAM) model, lupeol-loaded PLGA ocular implants showed antiangiogenic activity comparable to the FDA-approved anti-VEGF antibody Bevacizumab. Overall, our results suggest lupeol-loaded PLGA ocular implants were able to inhibit the angiogenic process by impairing both proliferation and migration of endothelial cells.

A safety study of high concentration and high frequency intravitreal injection of conbercept in rabbits

The novel anti-VEGF drug conbercept has been used in the treatment of several retinal neovascular diseases. Owning to the alteration of the structure, the newest drug is capable of combining more molecular targets and present higher affinity to the angiogenesis promoting factors. However, it is unknown whether it will cause any unwanted effects like other anti-VEGF agents. We studied the short-term safety of high concentration and high frequency intravitreal injection of conbercept in rabbits. Intraocular pressure, fundus-photography, ERGs were applied. Retinal morphology, the amount of apoptotic cells and protein levels of IL-6, IL-8 and TNF-α in the aqueous humor were determined. Retinal proteomics was detected using tandem mass tags (TMTs) quantitative mass spectrometry. The difference of IOP, ERGs, protein levels of inflammatory factors among rabbits received conbercept and PBS was not significant (P > 0.05). Fundus photographs and retinal morphology of animals in the conbercept-injected groups mimic those observed in the PBS-injected groups. No TUNEL-positive cell was seen in the retinal ganglion cell layer in the conbercept-injected groups. Proteomics did not show significant changes of inflammation or apoptosis associated proteins in the conbercept-injected eyes. We conclude that intravitreal injection of high concentration and high frequency conbercept is well tolerated at least in a short-term in rabbits.

Neovascular glaucoma after vitrectomy in patients with proliferative diabetic retinopathy

To evaluate the prevalence and risk factors of neovascular glaucoma (NVG) after vitrectomy in patients with vitreous hemorrhage associated with proliferative diabetic retinopathy (PDR). This retrospective, noncomparative, observational study included 127 eyes of 127 patients with PDR who received vitrectomy with a follow-up period of at least 6 months. The prevalence of NVG and associated risk factors were assessed including sex, age, previous panretinal photocoagulation, baseline intraocular pressure, combined phacovitrectomy, and pretreatment with intravitreal bevacizumab (IVB) before vitrectomy for the treatment of vitreous hemorrhage. NVG developed in 15 (11.8%) of 127 patients. Of the 15 eyes with NVG, 11 cases (73.3%) postoperatively developed NVG within 6 months. Postoperative NVG was associated with preoperative IVB treatment (odds ratio, 4.43; P = 0.019). The prevalence of NVG after vitrectomy was 11.8%, and an associated risk factor for NVG was preoperative IVB for the treatment of vitreous hemorrhage.

Alterations in intraocular cytokine levels following intravitreal ranibizumab

OBJECTIVE

Our previous work has shown that, after intravitreal bevacizumab (IVB) administration, decreases in the levels of vascular endothelial growth factor (VEGF)-A and placental growth factor (PlGF), along with increases in the levels of interleukin (IL)-8 and transforming growth factor (TGF)-β2, can be observed. It is not yet known if similar changes occur after intravitreal ranibizumab (IVR). The purpose of this study was to examine intraocular cytokine changes after IVR.

DESIGN

Prospective clinical study.

PARTICIPANTS

Subjects with proliferative diabetic retinopathy requiring pars plana vitrectomy (PPV) were recruited.

METHODS

Participants received IVR as pre-treatment before PPV. Aqueous humour levels of IL-8, VEGF-A, PlGF, and TGF-β2 were measured at time of pre-treatment and PPV. Results were analyzed using univariate statistical models.

RESULTS

A total of 14 participants were recruited. After IVR administration, we observed a decrease in the levels of VEGF-A and PlGF, and an increase in the levels of IL-8 and TGF-β2. These results were statistically significant only for VEGF-A (p = 0.0001) and IL-8 (p = 0.0002).

CONCLUSIONS

The changes in cytokine levels after IVR mirror the changes seen after IVB. Further studies are warranted in order to determine if there are any differences between IVB and IVR in this regard.

The impact of ranibizumab on the level of intercellular adhesion molecule type 1 in the vitreous of eyes with proliferative diabetic retinopathy

PURPOSE

This study was to investigate the impact of ranibizumab on the level of intercellular adhesion molecule type 1 (ICAM-1) in the vitreous of eyes with PDR.

METHODS

This is an interventional case-control study. A total of 82 eyes from 82 patients who had undergone vitreous surgery for the treatment of retinal disorders were included. Twenty-two eyes with PDR received an intravitreal ranibizumab injection (IVR) 3-7 days before vitrectomy and were grouped as 'PDR with recent IVR' or Group 1. Sixteen eyes with PDR received IVR more than 7 days before vitrectomy and were grouped as 'PDR with remote IVR' or Group 2. Twenty-two matched PDR eyes did not receive IVR before vitrectomy and were grouped as 'PDR without IVR' or Group 3. Finally, 22 eyes from 22 patients with idiopathic macular pucker (IMP) served as the 'non-diabetic control' group, or Group 4. Vitreous samples were obtained at the time of vitrectomy from all eyes, and the levels of vascular endothelium growth factor (VEGF) and ICAM-1 were analysed using ELISA.

RESULTS

PDR without IVR (Group 3) had the highest vitreous VEGF concentration; the difference was significant compared with those in the PDR with recent IVR (Group 1), PDR with remote IVR (Group 2) and the non-diabetic control group (Group 4) (p < 0.001). Group 2 had a lower vitreous VEGF level than Group 1 (p = 0.041). Group 1 had the highest vitreous ICAM-1 levels (p < 0.001 versus. Groups 2, 3 and 4); Group 2 had a lower vitreous ICAM-1 level than Group 3 (p = 0.028).

CONCLUSION

The vitreous fluid level of ICAM-1 was significantly increased within 1 week of IVR administration, but markedly decreased after a week of administration in eyes with PDR. This suggests that leucostasis, vascular leakage and endothelial dysfunction may be amplified in the early days after IVR, but that a therapeutic effect of IVR in these processes may appear after 1 week of ranibizumab administration in eyes with PDR.

Association of Complement C5 Gene Polymorphisms with Proliferative Diabetic Retinopathy of Type 2 Diabetes in a Chinese Han Population

Purpose

To investigate the association of C5 SNPs with proliferative diabetic retinopathy (PDR) of type 2 diabetes (T2D).

Methods

A total of four C5 SNPs including rs2269067, rs7040033, rs1017119 and rs7027797 were genotyped in 400 PDR patients with T2D (cases) and 600 non- proliferative diabetic retinopathy PDR (NPDR) with T2D patients (controls) by using PCR-RFLP method. mRNA expression was examined by real-time PCR. Cytokine production was detected by ELISA.

Results

The frequency of GG genotype of C5 rs2269067 was significantly increased in cases compared with controls (Pc = 3.4×10⁻⁵, OR = 1.87). And C5 mRNA expression was significantly increased in rs2269067 GG cases as compared with CG or CC cases (P = 0.003, P = 0.001, respectively). Moreover, the production of IL-6 was significantly increased in rs2269067 GG cases compared to CG cases or CC cases (P = 0.002, P = 0.001, respectively).

Conclusions

C5 rs2269067 GG genotype confers risk for PDR of T2D in Chinese han population and is associated with an elevated C5 mRNA expression and an increased IL-6 production.

Effect of intravitreal triamcinolone in diabetic macular edema unresponsive to intravitreal bevacizumab

PURPOSE

To evaluate the efficacy of intravitreal triamcinolone injection in diabetic macular edema unresponsive to intravitreal bevacizumab.

METHODS

Patients with diabetic macular edema unresponsive to at least three monthly intravitreal bevacizumabs were included. At least 2 months after the last intravitreal bevacizumab, intravitreal triamcinolone was performed after obtaining an aqueous humor sample. Multiplex cytokine array was used to assay vascular endothelial growth factor, interleukin (IL)-2, IL-6, IL-8, tumor necrosis factor-α, and transforming growth factor-β2. Best-corrected visual acuity and central subfield thickness were evaluated from Month 0 to 3.

RESULTS

Twenty eyes were enrolled. The mean best-corrected visual acuity was 47.1 ± 18.9 letters at baseline, and significantly increased to 53.3 ± 19.7 letters at 1 month (P = 0.002) and 52.4 ± 19.1 letters at 2 months (P = 0.041). These visual gains were not sustained at 3 months (50.9 ± 18.6; P = 0.204). A decrease in central subfield thickness more than 11% of baseline occurred in 12 eyes at 1 month. Multivariate analysis showed that intraocular levels of IL-8 (β = 0.538 P = 0.006) was an independent factor for anatomic response at 1 month.

CONCLUSION

Intravitreal triamcinolone has a role in patients who are unresponsive to intravitreal bevacizumab over the short-term. Elevated intraocular IL-8 levels were related to the efficacy.

Pharmacokinetics, pharmacodynamics and pre-clinical characteristics of ophthalmic drugs that bind VEGF

Drugs that prevent the binding of VEGF to its trans-membrane cognate receptors have revolutionized the treatment of the most important chorioretinal vascular disorders: exudative age-related macular degeneration, diabetic macular edema, and retinal vein occlusions. Pegaptanib, which binds to VEGF165 and longer isoforms, ranibizumab and bevacizumab, which bind all VEGF-A isoforms, and aflibercept, which binds VEGF-A, VEGF-B, and placental growth factor, all bind VEGF165 with high affinity. The drugs have relatively long half-lives (7 to 10 days) after intravitreal depot injections and clinical durations of action that usually exceed 4 weeks. Plasma VEGF concentrations decrease after intravitreal injections of bevacizumab and aflibercept because their systemic half-lives are extended by their Fc fragments. Extensive in vitro and in vivo testing shows that the drugs prevent VEGF-mediated activation of endothelial cells while exhibiting little evidence of toxicity. Further anti-VEGF drug development is on-going.

[VEGF inhibitors in vitreoretinal interventions]

Vascular endothelial growth factor (VEGF) inhibitors are being used for an increasing number of indications. Beyond the classical use in exudative macular degeneration and macular edema, they are being used, for example off-label as additive treatment together with panretinal laser photocoagulation or in preparation for vitrectomy for ischemic retinopathy. In preparation for vitreoretinal surgery VEGF inhibitors are usually given prior to surgery. When given as an adjunct to laser treatment, VEGF inhibitors can be given either consecutively or parallel to laser photocoagulation. In most cases, however, anti-VEGF treatment does not render laser coagulation dispensable. The greatest danger with anti-VEGF treatment in the context of ischemic retinopathies lies in the fact that proliferative membranes are misjudged or overlooked. In these cases, anti-VEGF treatment can induce contraction of these membranes with induction of consecutive tractional retinal detachment. This review summarizes the current knowledge on VEGF inhibition as an adjunct to vitreoretinal surgery and also points out the gaps in the current knowledge and the need for further research.