Effects of intravitreal injection of bevacizumab on inflammatory cytokines in the vitreous with proliferative diabetic retinopathy

The IL-12 family of cytokines: pathogenetic role in diabetic retinopathy and therapeutic approaches to correction

One vision-threatening side effect of systematic diabetes mellitus is diabetic retinopathy (DR). Recent studies have revealed that the development and progression of DR depend critically on inflammation resulting from diabetes. By attracting leukocytes to endothelium, the higher production of the inflammatory mediators induces degeneration of retinal capillaries, hence increasing vascular permeability and thrombosis probability. The leukocytes that are recruited eventually generate additional proinflammatory and proangiogenic substances, resulting in the increased infiltration of leukocytes in the retina. This process also leads to changes in the blood retinal barrier and the formation of new blood vessels, which helps to counteract the damage caused by the blockage of blood flow. IL-12 family members, IL-12, IL-23, IL-27, and IL-35, play a crucial role in regulating the responses of T helper (Th)1 and Th17 cell populations. The collected data from studies investigating the levels of IL-12 family members in the blood and eye tissues suggest that IL-12 is linked to DR, indicating that it may have a role in the development of DR as a sequential component of the immune response. This review specifically examines the possibility of using IL-12 family cytokines as a therapeutic approach for diabetes, taking into consideration their involvement in the development of DR.

Comparison of efficacy and safety of intravitreal ranibizumab and conbercept before vitrectomy in Chinese proliferative diabetic retinopathy patients: a prospective randomized controlled trial

BACKGROUND

To compare the efficacy and safety of preoperative intravitreal injections of ranibizumab and conbercept in Chinese proliferative diabetic retinopathy (PDR) patients.

METHODS

This prospective randomized controlled trial enrolled 90 eyes of 80 patients with PDR. Forty-four eyes of 40 patients that received intravitreal ranibizumab (IVR) injections (0.5 mg/0.05 mL) before vitreous surgeries were assigned to the IVR group. Forty-six eyes of 40 patients that received intravitreal conbercept (IVC) injections (0.5 mg/0.05 mL) before vitreous surgeries were assigned to the IVC group. Intraoperative and postoperative indices were assessed for further comparison between the two groups.

RESULTS

There were no statistically significant differences in all surgery indices, including intraoperative indices (surgery time, P = 0.225; intraoperative bleeding, P = 0.808; endodiathermy use, P = 0.693; incidence of iatrogenic retinal breaks, P = 0.740; relaxing retinotomy, P = 0.682; retinal reattachment, P = 0.682 and silicone oil tamponade, P = 0.814) and postoperative indices (postoperative vitreous hemorrhage (VH), P = 0.808; neovascular glaucoma (NVG), P = 0.964; recurrent retinal detachment, P = 0.531; postoperative fibrovascular proliferation progression, P = 0.682 and reoperation, P = 0.955) between the two groups. There were no statistically significant differences in best-corrected visual acuity (BCVA) at each follow-up visit (P = 0.939, 0.669, 0.741 and 0.717, respectively) or in central retinal thickness (CRT) (P = 0.976, 0.699, 0.551 and 0.686, respectively). As for safety profile, both groups had no ocular or system adverse events during the observation period.

CONCLUSIONS

IVR and IVC as a pretreatment of vitrectomy had similar efficacy and safety profile for Chinese PDR patients.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov ( NCT05414149 ).

Hyalocytes in proliferative vitreo-retinal diseases

Introduction

Hyalocytes are sentinel macrophages residing within the posterior vitreous cortex anterior to the retinal inner limiting membrane (ILM). Following anomalous PVD and vitreoschisis, hyalocytes contribute to paucicellular (vitreo-macular traction syndrome, macular holes) and hypercellular (macular pucker, proliferative vitreo-retinopathy, proliferative diabetic vitreo-retinopathy) diseases.

Areas covered

Studies of human tissues employing dark-field, phase, and electron microscopy; immunohistochemistry; and in vivo imaging of human hyalocytes.

Expert opinion

Hyalocytes are important in early pathophysiology, stimulating cell migration and proliferation, as well as subsequent membrane contraction and vitreo-retinal traction. Targeting hyalocytes early could mitigate advanced disease. Ultimately, eliminating the role of vitreous and hyalocytes may prevent proliferative vitreo-retinal diseases entirely.

Prospective Comparison of Surgery Outcome Between Preoperative and Intraoperative Intravitreal Injection of Ranibizumab for Vitrectomy in Proliferative Diabetic Retinopathy Patients

INTRODUCTION

To compare the efficacy and safety of intravitreal injections of ranibizumab (IVR) before and at the end of vitrectomy in proliferative diabetic retinopathy (PDR) patients.

METHODS

A prospective comparative study was performed on 60 eyes of 52 PDR patients who received ranibizumab injection (0.5 mg/0.05 ml) 3-5 days before vitrectomy (preoperative group) and 55 eyes of 50 PDR patients who received ranibizumab injection (0.5 mg/0.05 ml) at the end of vitrectomy (intraoperative group). Intra- and postoperative indices were collected for further comparison.

RESULTS

Postoperative best-corrected visual acuity (BCVA) in preoperative group was better than in intraoperative group at 1 week after surgery (P < 0.05) but comparable at 1- and 3-month follow-up (P = 0.20 and P = 0.37, respectively). Central retinal thickness (CRT) in preoperative group was lower than in intraoperative group at 1 week postoperatively (P < 0.05), but comparable at 1- and 3-month follow-up (P = 0.39 and P = 0.77, respectively). The average surgery time was significantly shorter in preoperative group than in intraoperative group (61.50 ± 11.44 min vs. 74.49 ± 12.01 min, P < 0.01). The incidence of intraoperative bleeding was significant lower in preoperative group than in intraoperative group (21.7% vs. 40.0%, P < 0.05). Moreover, the incidence of intraocular electrocoagulation use, iatrogenic retinal breaks, relaxing retinotomy and silicone oil tamponade were all significantly lower in preoperative group than that in intraoperative group (P < 0.05, respectively). The incidences of postoperative vitreous hemorrhage (VH), neovascular glaucoma (NVG), recurrent retinal detachment, postoperative fibrovascular proliferation progression and reoperation showed no statistical differences between the two groups (P > 0.05, respectively). Both groups had no ocular or system adverse events during observation period.

CONCLUSION

In vitrectomy for PDR, preoperative IVR can significantly reduce surgery time and lower the incidence of intraoperative bleeding, intraocular electrocoagulation use, iatrogenic retinal breaks, relaxing retinotomy and silicone oil tamponade during surgery and gain short-term better postoperative BCVA and thinner CRT.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier, NCT05408416).

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.

The Vitreous Ecosystem in Diabetic Retinopathy: Insight into the Patho-Mechanisms of Disease

Diabetic retinopathy is one of the leading causes of blindness in the world with the incidence of disease ever-increasing worldwide. The vitreous humor represents an extensive and complex interactive arena for cytokines in the diabetic eye. In recent decades, there has been significant progress in understanding this environment and its implications in disease pathophysiology. In this review, we investigate the vitreous ecosystem in diabetic retinopathy at the molecular level. Areas of concentration include: the current level of knowledge of growth factors, cytokine and chemokine mediators, and lipid-derived metabolites in the vitreous. We discuss the molecular patho-mechanisms of diabetic retinopathy based upon current vitreous research.

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.

Evaluation of vitrectomy combined preoperative intravitreal ranibizumab and postoperative intravitreal triamcinolone acetonide for proliferative diabetic retinopathy

BACKGROUND

To explore the treatment efficacy of the combination of preoperative intravitreal ranibizumab (IVR) and postoperative intravitreal triamcinolone acetonide (IVTA) in patients undergoing pars plana vitrectomy (PPV) for proliferative diabetic retinopathy (PDR).

METHODS

A retrospective comparative study was performed on 128 eyes of 128 patients who had PDR and underwent PPV. Patients who received a single PPV were assigned to Group A. Those who received PPV with preoperative IVR were assigned to Group B. Patients in Group C underwent PPV combined preoperative IVR and postoperative IVTA. Intraoperative findings, changes in mean best-corrected visual acuity (BCVA) and postoperative adverse events, were retrospectively evaluated at 6-month follow-up.

RESULTS

The incidences of iatrogenic breaks, severe intraoperative bleeding, using long-term internal tamponade agents, recurrent vitreous hemorrhage (VH), and duration of surgery were statistically significantly less in Group B and Group C than in Group A. The postoperative BCVA was statistically significantly better in Groups B and Group C than in Group A, respectively, at 1 month after surgery. The mean 3-month postoperative visual acuity was better in Group C. The incidence of high intraocular pressure (IOP) was significantly higher in Group C at the first postoperative week. There were no statistically significant differences in the incidence of exudative retinal detachment and choroidal detachment among the three groups.

CONCLUSION

In patients undergoing PPV for PDR, preoperative IVR significantly reduced the occurrence of intraoperative and postoperative complications, and the combination of preoperative IVR and postoperative IVTA can better improve the postoperative visual outcome.

Proinflammatory and angiogenesis-related cytokines in vitreous samples of highly myopic patients

PURPOSE

To determine the concentrations of vitreous proinflammatory cytokines and angiogenesis-related growth cytokines in highly myopic (HM) patients and controls.

METHODS

Vitreous humor (VH) was obtained from patients during vitrectomy for rhegmatogenous retinal detachment (RRD), myopic retinoschisis (MRS), idiopathic epiretinal membrane (ERM), or macular hole (MH). High myopia was defined as an axial length (AL) of ≥26.0 mm and a spherical equivalent refractive error more negative than -6.0 D. A multiplex fluorescent-bead-based immunoassay was employed to measure the levels of 29 designated cytokines. The results were compared across groups.

RESULTS

Seventy-eight VH samples were collected from 78 patients (36 HM versus 42 controls). Vascular endothelial growth factor (VEGF) was significantly higher in the VH samples from HM patients than in those from the controls. Five inflammation-related factors, interferon γ (IFN-γ), interleukin 6 (IL6), IFN-γ-induced protein 10 (IP-10), eotaxin, and macrophage inflammatory protein 1α (MIP-1α), were significantly higher in the HM group than in the control group. The vitreous concentrations of well-known angiogenic growth factors monocyte chemoattractant protein 1 (MCP1) and IL5 were significantly elevated in the VH samples from HM patients.

CONCLUSIONS

Proinflammatory cytokines and angiogenic growth factors were elevated in the VH of HM patients, suggesting that an elevated inflammatory status and higher levels of angiogenic factors are present in eyes with HM.

Vascular toxicity associated with anti-angiogenic drugs

Over the past two decades, the treatment of cancer has been revolutionised by the highly successful introduction of novel molecular targeted therapies and immunotherapies, including small-molecule kinase inhibitors and monoclonal antibodies that target angiogenesis by inhibiting vascular endothelial growth factor (VEGF) signaling pathways. Despite their anti-angiogenic and anti-cancer benefits, the use of VEGF inhibitors (VEGFi) and other tyrosine kinase inhibitors (TKIs) has been hampered by potent vascular toxicities especially hypertension and thromboembolism. Molecular processes underlying VEGFi-induced vascular toxicities still remain unclear but inhibition of endothelial NO synthase (eNOS), reduced nitric oxide (NO) production, oxidative stress, activation of the endothelin system, and rarefaction have been implicated. However, the pathophysiological mechanisms still remain elusive and there is an urgent need to better understand exactly how anti-angiogenic drugs cause hypertension and other cardiovascular diseases (CVDs). This is especially important because VEGFi are increasingly being used in combination with other anti-cancer dugs, such as immunotherapies (immune checkpoint inhibitors (ICIs)), other TKIs, drugs that inhibit epigenetic processes (histone deacetylase (HDAC) inhibitor) and poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors, which may themselves induce cardiovascular injury. Here, we discuss vascular toxicities associated with TKIs, especially VEGFi, and provide an up-to-date overview on molecular mechanisms underlying VEGFi-induced vascular toxicity and cardiovascular sequelae. We also review the vascular effects of VEGFi when used in combination with other modern anti-cancer drugs.

Proliferative diabetic retinopathy without preoperative pan-retinal photocoagulation is associated with higher levels of intravitreal IL-6 and postoperative inflammation

Purpose

Intravitreal cytokine levels and differences in the severity of postoperative inflammation in patients with proliferative diabetic retinopathy (PDR) were compared between subjects treated with pan-retinal photocoagulation (PRP) prior to undergoing vitreous surgery and those treated similarly during the surgery.

Subjects and methods

We examined 130 eyes of PDR patients who underwent an initial surgical procedure at Hirosaki University Hospital. A total of 67 out of the 130 eyes were treated with PRP prior to surgery (preoperative group), while 63 underwent similar treatment during surgery (intraoperative group). Vitreous fluid was collected at the start of the vitreous surgical procedure. Following vitrectomy, intraoperative PRP was completed during the surgery in the intraoperative group. This procedure was added to the peripheral part as needed in the preoperative group. The results for the levels of 27 cytokines, including vascular endothelial growth factor (VEGF), were measured using multiplex assays and compared between the groups. For determining postoperative inflammation, eyes in which fibrin was observed for 3 days or longer in the anterior chamber or vitreous cavity were considered to have fibrin deposition. The rate of fibrin deposition was compared between these groups.

Results

Among the vitreous cytokines examined, there was no significant difference in the VEGF levels between the groups (p = 0.70). In contrast, the IL-6 level was significantly higher in the intraoperative group (2813.2 ± 6022.2 vs. 1248.5 ± 1442.2 pg/ml, p = 0.048). Furthermore, the fibrin deposition rate was significantly higher in the intraoperative (44.4%) versus the preoperative group (14.9%) (p = 0.0002).

Conclusion

Severe postoperative inflammation was frequently seen in patients who did not undergo preoperative PRP, which may have been due to the performance of the procedure during the surgery. Moreover, these results may also be associated with a higher level of intravitreal IL-6.

Aqueous Humor Cytokines and Long-Term Response to Anti-Vascular Endothelial Growth Factor Therapy in Diabetic Macular Edema

PURPOSE

To determine the association of aqueous humor cytokine concentrations with long-term treatment response to anti-vascular endothelial growth factor (VEGF) agents in diabetic macular edema (DME).

DESIGN

Retrospective case series.

METHODS

Pooled data of aqueous humor cytokine concentrations collected at baseline and 2-month follow-up (2 injections) for treatment-naïve eyes with center-involving DME previously enrolled in a prospective study were reviewed. Subjects receiving intravitreal anti-VEGF injections outside of study protocol as per standard of care were classified into Responders versus Nonresponders based on qualitative assessment of optical coherence tomography for persistence of DME at longitudinal follow-up visits.

RESULTS

Of the 41 eyes, 85% were classified as Responders with a significant decline in baseline central subfield thickness and macular volume (P values < .001), and 15% were identified as Nonresponders to anti-VEGF therapy over 51.4 ± 18.7 months of follow-up. No significant difference in baseline aqueous humor VEGF concentration was noted, while at the 2-month follow-up the Nonresponder group had a significantly higher VEGF concentration compared with the Responder group (451.5 ± 690.9 pg/mL vs 113.7 ± 211.4 pg/mL; P = .02). The Responder group also demonstrated a significant decline from baseline to 2-month follow-up in concentration of intercellular adhesion molecule-1 (P < .001), interleukin-10 (P = .041), monocyte chemotactic protein-1 (P = .046), placental growth factor (P = .027), and transforming growth factor-β2 (P = .017).

CONCLUSIONS

Aqueous humor cytokine concentrations serve as an early biomarker for long-term response to anti-VEGF therapy and may enable more effective treatment regimens that improve anatomical outcomes in eyes with DME.

IL-1 Family Members Mediate Cell Death, Inflammation and Angiogenesis in Retinal Degenerative Diseases

Inflammation underpins and contributes to the pathogenesis of many retinal degenerative diseases. The recruitment and activation of both resident microglia and recruited macrophages, as well as the production of cytokines, are key contributing factors for progressive cell death in these diseases. In particular, the interleukin 1 (IL-1) family consisting of both pro- and anti-inflammatory cytokines has been shown to be pivotal in the mediation of innate immunity and contribute directly to a number of retinal degenerations, including Age-Related Macular Degeneration (AMD), diabetic retinopathy, retinitis pigmentosa, glaucoma, and retinopathy of prematurity (ROP). In this review, we will discuss the role of IL-1 family members and inflammasome signaling in retinal degenerative diseases, piecing together their contribution to retinal disease pathology, and identifying areas of research expansion required to further elucidate their function in the retina.

Relationship between aqueous humor cytokine level changes and retinal vascular changes after intravitreal aflibercept for diabetic macular edema

The aim of this work was to investigate the changes in aqueous humor cytokine levels after intravitreal injection of aflibercept in diabetic macular edema (DME) and to evaluate the relationship between cytokines modifications and central macular thickness (CMT) and retinal/choroidal vascular changes using structural and functional optical coherence tomography (OCT). Aqueous concentrations of 38 cytokines were measured via multiplex bead assay. In addition, spectral domain OCT and OCT angiography with SSADA software (XR Avanti® AngioVue) were performed at baseline and after intravitreal injections. VEGF, IL-6, IL-5, IL-1β, Eotaxin, GRO, IL-12p40, IL-12p70, IL-1RA, Flt-3L and IP-10 showed a statistically significant decrease through the follow-up (p < 0.05; p < 0.001), while Fraktalkine and GM-CSF significantly increased (p < 0.05). Best corrected visual acuity significantly increased and CMT significantly decreased during follow-up (p < 0.001 and p = 0.013). Superficial capillary plexus and deep capillary plexus density significantly increased (p < 0.001 and p = 0.014). A positive relation was found between GRO, VEGF, Fraktalkine, IP-10, IL-12p70 aqueous humor levels and CMT (p < 0.05; p < 0.001). Aflibercept is a primary anti-VEGF treatment producing a decrease of DME due to the reduction of vascular permeability, nevertheless other inflammatory cytokines showed modification after aflibercept intravitreal injections probably related to edema modification or to an interaction of aflibercept with other inflammatory cytokines.

Efficacy comparison of intravitreal injections of conbercept and ranibizumab for severe proliferative diabetic retinopathy

OBJECTIVE

To determine the efficacy of preoperative intravitreal injections of conbercept (IVC) and ranibizumab (IVR) on postoperative best-corrected visual acuity (BCVA), vitreous hemorrhage (VH), and neovascular glaucoma (NVG) in a population with proliferative diabetic retinopathy (PDR) undergoing vitrectomy.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

386 patients with severe PDR (428 eyes).

METHODS

The patients who did not receive IVC or IVR were assigned to group A (125 eyes), the patients who received IVR (0.5 mg) were assigned to group B (146 eyes), and the patients who received IVC (0.5 mg) were assigned to group C (157 eyes).

RESULTS

Both group B (p = 0.009) and group C (p = 0.002) had better postoperative BCVA than group A. Early postoperative VH occurred significantly less frequently in group B (22.60%; p = 0.007) and group C (12.10%; p < 0.001) than in group A (37.60%). Importantly, the incidences of postoperative NVG in group B (2.74%; p = 0.001) and group C (0.64%; p < 0.001) were both significantly less than that in group A (15.20%). However, there was no significant difference in the incidences of postoperative NVG between groups B and C (p = 0.325).

CONCLUSIONS

The contribution of preoperative IVC to an improved BCVA for patients with severe PDR was better than that of IVR, and IVC decreased the risk of postoperative early VH. Pretreatment with IVC or IVR reduced the incidence of postoperative NVG based on the 24-month follow-up data.

Diverse roles of macrophages in intraocular neovascular diseases: a review

Macrophages are involved in angiogenesis, and might also contribute to the pathogenesis of intraocular neovascular diseases. Recent studies indicated that macrophages exert different functions in the process of intraocular neovascularization, and the polarization of M1 and M2 phenotypes plays extremely essential roles in the diverse functions of macrophages. Moreover, a large number of cytokines released by macrophages not only participate in macrophage polarization, but also associate with retinal and choroidal neovascular diseases. Therefore, macrophage might be considered as a novel therapeutic target to the treatment of pathological neovascularization in the eye. This review mainly summarizes diverse roles of macrophages and discusses the possible mechanisms in retinal and choroidal neovascularization.

Anti-VEGF therapy for central retinal vein occlusion caused by tuberculosis-associated uveitis: a case report

BACKGROUND

Tuberculosis (TB)-associated uveitis presents periphlebitis, occasionally causing central retinal vascular occlusion (CRVO). Intravitreal injection of ranibizumab (IVR) is an effective treatment for CRVO, which improves macular edema (ME) by reducing vascular permeability and prevents progression of retinal nonperfusion in CRVO. We report a case of CRVO due to TB-associated uveitis, which initially remitted by repeated IVR as an adjunct to anti-TB therapy and systemic corticosteroids, but subsequently led to severe vitreous hemorrhage (VH).

CASE PRESENTATION

A 28-year-old man was referred to our hospital with a 2-week history of uveitis in his right eye. Ophthalmoscopic examination of the right eye revealed fine keratoprecipitates and moderate cell infiltration into the anterior chamber and vitreous. No obvious retinal lesion was observed. Despite initiation of topical corticosteroids, CRVO developed a few weeks later in the right eye. TB-associated uveitis was diagnosed based on a positive tuberculin skin test and interferon-γ release assay in addition to the ocular findings. Anti-TB therapy together with IVR and systemic corticosteroids was initiated. Although fundus findings associated with CRVO gradually improved, CRVO with VH recurred before the fourth IVR. Although IVR was continued, VH progressed to obscure fundus observation. Therefore, vitrectomy and panretinal photocoagulation were performed. After surgery, ocular inflammation was controlled, and anti-TB therapy was continued for 6 months and was suspended.

CONCLUSION

In addition to anti-TB therapy with or without corticosteroids, panretinal photocoagulation for retinal nonperfusion area in TB-associated uveitis should be performed for preventing neovascularization that may cause VH, and this role of panretinal photocoagulation cannot be replaced by anti-VEGF therapy.

Effect of bevacizumab on the expression of fibrosis-related inflammatory mediators in ARPE-19 cells

AIM

To investigate the effect of anti-vascular epithelial growth factor (VEGF) agents on the expression of fibrosis-related inflammatory mediators under normoxic and hypoxic conditions, and to further clarify the mechanism underlying fibrosis after anti-VEGF therapy.

METHODS

Human retinal pigment epithelial (RPE) cells were incubated under normoxic and hypoxic conditions. For hypoxia treatment, CoCl₂ at 200 µmol/L was added to the media. ARPE-19 cells were treated as following: 1) control group: no treatment; 2) bevacizumab group: bevacizumab at 0.25 mg/mL was added to the media; 3) hypoxia group: CoCl₂ at 200 µmol/L was added to the media; 4) hypoxia+bevacizumab group: CoCl₂ at 200 µmol/L and bevacizumab at 0.25 mg/mL were added to the media. The expression of interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor (TNF)-α were evaluated using real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) at 6, 12, 24 and 48h.

RESULTS

Both mRNA and protein levels of IL-1β, IL-6 and IL-8 were statistically significantly higher in the bevacizumab group than in the control group at each time point, and TNF-α gene and protein expression was only significantly higher only at 24 and 48h (P<0.05). Under hypoxic conditions, bevacizumab significantly increased the expression of IL-1β, IL-6, IL-8 and TNF-α at 6, 12, 24 and 48h (P<0.05). IL-1β, IL-8 and TNF-α peaked at 24h and IL-6 peaked at 12h after the bevacizumab treatment under both normoxic and hypoxic conditions.

CONCLUSION

Treatment of ARPE-19 cells with bevacizumab can significantly increase the expression of fibrosis-related inflammatory mediators under both normoxic and hypoxic conditions. Inflammatory factors might be involved in the process of fibrosis after anti-VEGF therapy, and the up-regulation of inflammatory factors induced by anti-VEGF drugs might promote the fibrosis process.

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.

Level of Vascular Endothelial Growth Factor in the Vitreous Fluid of Proliferative Diabetic Retinopathy Patients and Prognosis after Vitrectomy

PURPOSE

The aim of this study was to evaluate the relationship between the intravitreal vascular endothelial growth factor (VEGF) level and prognosis of proliferative diabetic retinopathy (PDR).

METHODS

The study involved 136 eyes of 114 PDR patients who underwent an initial vitrectomy between 2006 and 2008. Intravitreal VEGF levels were determined using Bio-Plex® (Bio-Rad), with levels of 5,000 pg/mL or more classified as high-VEGF (45 eyes) and levels lower than 5,000 pg/mL as low-VEGF (91 eyes). Diabetic control, PDR severity, and frequency of postoperative complications were compared between the groups.

RESULTS

There was no significant difference in preoperative status between the groups. In the low-VEGF group, a reoperation was required due to postoperative complications in 2 eyes (2.2%); 1 with vitreous hemorrhage (VH) and 1 with retinal detachment (RD). In contrast, a reoperation was required in 8 eyes (17.8%) in the high-VEGF group; 3 with VH, 2 with RD, and 3 with neovascular glaucoma. The difference between the groups was significant. There was a statistically lower postoperative corrected visual acuity logMAR (6 months after surgery) in the high-VEGF than in the low-VEGF group (p = 0.02, unpaired t test).

CONCLUSION

Current findings indicate that careful observation is needed in patients with elevated VEGF levels.

The Vitreomacular Interface in Diabetic Retinopathy

Diabetic retinopathy (DR) is a leading health concern and a major cause of blindness. DR can be complicated by scar tissue formation, macular edema, and tractional retinal detachment. Optical coherence tomography has found that patients with DR often have diffuse retinal thickening, cystoid macular edema, posterior hyaloid traction, and tractional retinal detachment. Newer imaging techniques can even detect fine tangential folds and serous macular detachment. The interplay of the vitreous and the retina in the progression of DR involves multiple chemokine and other regulatory factors including VEGF. Understanding the cells infiltrating pathologic membranes at the vitreomacular interface has opened up the possibility of new targets for pharmacotherapy. Vitrectomies for DR remain a vital tool to help relieve tension on the macula by removing membranes, improving edema absorption, and eliminating the scaffold for new membrane formation. Newer treatments such as triamcinolone acetonide and VEGF inhibitors have become essential as a rapid way to control DR at the vitreomacular interface, improve macular edema, and reduce retinal neovascularization. These treatments alone, and in conjunction with PRP, help to prevent worsening of the VMI in patients with DR.

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.

Biomarkers in diabetic retinopathy and the therapeutic implications

The main problem both in type 1 (T1DM) and type 2 (T2DM) diabetes is the development of chronic vascular complications encompassing micro- as well as macrocirculation. Chronic complications lower the quality of life, lead to disability, and are the cause of premature death in DM patients. One of the chronic vascular complications is a diabetic retinopathy (DR) which leads to a complete loss of sight in DM patients. Recent trials show that the primary cause of diabetic retinopathy is retinal neovascularization caused by disequilibrium between pro- and antiangiogenic factors. Gaining knowledge of the mechanisms of action of factors influencing retinal neovascularization as well as the search for new, effective treatment methods, especially in advanced stages of DR, puts special importance on research concentrating on the implementation of biological drugs in DR therapy. At present, it is antivascular endothelial growth factor and antitumor necrosis factor that gain particular significance.