Increased vitreous concentrations of MCP-1 and IL-6 after vitrectomy in patients with proliferative diabetic retinopathy: possible association with postoperative macular oedema

Effect of anti-vascular endothelial growth factor on early-stage post-vitrectomy macular edema in patients with proliferative diabetic retinopathy

PURPOSE

To investigate the effectiveness of anti-vascular endothelial growth factor (VEGF) therapy on post-vitrectomy macular edema (PVME) and determine the risk factors for PVME recovery.

METHODS

This retrospective study included 179 eyes of 179 patients who underwent pars plana vitrectomy for proliferative diabetic retinopathy and developed PVME within 3 months after surgery. Eyes were grouped according to postoperative anti-VEGF treatment.

RESULTS

Central retinal thickness (CRT) decreased significantly from baseline to 3-month follow-up in groups with (509.9 ± 157.2 μm vs. 401.2 ± 172.1 μm, P < 0.001) or without (406.1 ± 96.1 μm vs. 355.1 ± 126.0 μm, P = 0.008) postoperative anti-VEGF treatment. Best-corrected visual acuity (BCVA) did not differ between the two groups during follow-up. In the group not receiving anti-VEGF therapy, BCVA was significantly improved at 1, 2, and 3 months (P = 0.007, P < 0.001, and P < 0.001, respectively), while in the anti-VEGF group, BCVA was significantly improved at 1 and 3 months (P = 0.03 and P < 0.001). A thicker baseline CRT (β = 0.44; 95% confidence interval, 0.26-0.61; P < 0.001) was significantly associated with decreasing CRT.

CONCLUSION

PVME tends to spontaneously resolve in the early postoperative period. The effect of anti-VEGF therapy in the first 3 months after diagnosis appears to be limited.

Interleukin-17A in diabetic retinopathy: The crosstalk of inflammation and angiogenesis

Diabetic retinopathy (DR) is a severe ocular complication of diabetes which can leads to irreversible vision loss in its late-stage. Chronic inflammation results from long-term hyperglycemia contributes to the pathogenesis and progression of DR. In recent years, the interleukin-17 (IL-17) family have attracted the interest of researchers. IL-17A is the most widely explored cytokine in IL-17 family, involved in various acute and chronic inflammatory diseases. Growing body of evidence indicate the role of IL-17A in the pathogenesis of DR. However, the pro-inflammatory and pro-angiogenic effect of IL-17A in DR have not hitherto been reviewed. Gaining an understanding of the pro-inflammatory role of IL-17A, and how IL-17A control/impact angiogenesis pathways in the eye will deepen our understanding of how IL-17A contributes to DR pathogenesis. Herein, we aimed to thoroughly review the pro-inflammatory role of IL-17A in DR, with focus in how IL-17A impact inflammation and angiogenesis crosstalk.

Comparison of the cytokines levels in aqueous humor in vitrectomized eyes versus non-vitrectomized eyes with diabetic macular edema

BACKGROUND

This study was conducted to compare concentrations of VEGF family growth factors, inflammation-related factors, and adhesion molecules in the aqueous humor of eyes with diabetic macular edema (DME), with and without prior vitrectomy.

METHODS

A total of 31 eyes were included, 11 with DME that had undergone vitrectomy, 9 with DME but without vitrectomy, and 11 from age-related cataract patients as controls. The concentrations of cytokines including TNF-α, IL-6, IL-8, IP-10, MCP-1, IFN-γ, MIP-1 α, MIP-1 β, PECAM-1, MIF, VCAM-1, ICAM-1, PIGF were quantified using Luminex Human Discovery Assay. Central macular thickness (CMT) values of all eyes were measured using optical coherence tomography (OCT).

RESULTS

(1) Vitrectomized DME eyes exhibited significantly higher levels of IL-6 and IL-8 compared to non-vitrectomized eyes (P < 0.05). (2) In vitrectomized group, after Benjamini-Hochberg correction, there was a significant positive correlation between the levels of VEGF and PlGF (rs = 0.855, P < 0.05), as well as the levels of TNF-α and IFN-γ (rs = 0.858, P < 0.05). In non-vitrectomized group, significant positive correlations were found between VEGF and PlGF levels after correcting for multiple comparisons (rs = 0.9, P < 0.05). (3) In non-vitrectomized group, the concentrations of VEGF and PlGF in aqueous humor were significantly positively correlated with CMT values (rs = 0.95, P < 0.05; rs = 0.9, P < 0.05, respectively).

CONCLUSIONS

The concentrations of IL-6 and IL-8 in the aqueous humor were significantly higher in vitrectomized DME eyes compared to nonvitrectomized DME eyes and the levels of VEGF were similar in the two groups, suggesting that inflammation after vitrectomy may be a key factor in the occurrence and development of DME.

Effects of Intravitreal Ranibizumab Injection on Peripheral Retinal Microcirculation and Cytokines in Branch Retinal Vein Occlusion with Macular Edema

Background and Objectives: To investigate peripheral blood flow in retinal vessels and vessel diameters after intravitreal ranibizumab injection (IRI) and the relationship between these parameters and cytokines in branch retinal vein occlusion (BRVO) with macular edema. Materials and Methods: We assessed relative flow volume (RFV) and the width of the main and branch retinal arteries and veins in the occluded and non-occluded regions before and after IRI in 37 patients with BRVO and macular edema. Measurements were made using laser speckle flowgraphy (LSFG). When performing IRI, we obtained samples of aqueous humor and analyzed them using the suspension array method to evaluate vascular endothelial growth factor (VEGF), placental growth factor (PlGF), platelet-derived growth factor (PDGF)-AA, soluble intercellular adhesion molecule (sICAM)-1, monocyte chemoattractant protein 1 (MCP-1), interleukin (IL)-6, IL-8, and interferon-inducible 10-kDa protein (IP-10). Results: In both retinal regions, before and after IRI, the RFV in the main artery and vein showed a significant correlation with the summed RFV in the respective branch vessels 1 and 2. In the occluded region, the RFV in the main vein was significantly negatively correlated with MCP-1, PDGF-AA, IL-6, and IL-8; the RFV in branch vein 1 was significantly negatively correlated with PlGF, MCP-1, IL-6, and IL-8; PDGF-AA was significantly negatively correlated with the width of the main and branch veins; and the RFVs of the main artery and vein decreased significantly from before to 1 month after IRI. Conclusions: Contrary to expectations, the study found that anti-VEGF therapy does not affect RFV in arteries and veins in patients with BRVO and macular edema. Furthermore, retinal blood flow is poor in patients with high MCP-1, IL-6, and IL-8. Finally, high PDGF-AA may result in smaller venous diameters and reduced retinal blood flow.

Vitreous humor proteome: unraveling the molecular mechanisms underlying proliferative and neovascular vitreoretinal diseases

Proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), and neovascular age-related macular degeneration (nAMD) are among the leading causes of blindness. Due to the multifactorial nature of these vitreoretinal diseases, omics approaches are essential for a deeper understanding of the pathophysiologic processes underlying the evolution to a proliferative or neovascular etiology, in which patients suffer from an abrupt loss of vision. For many years, it was thought that the function of the vitreous was merely structural, supporting and protecting the surrounding ocular tissues. Proteomics studies proved that vitreous is more complex and biologically active than initially thought, and its changes reflect the physiological and pathological state of the eye. The vitreous is the scenario of a complex interplay between inflammation, fibrosis, oxidative stress, neurodegeneration, and extracellular matrix remodeling. Vitreous proteome not only reflects the pathological events that occur in the retina, but the changes in the vitreous itself play a central role in the onset and progression of vitreoretinal diseases. Therefore, this review offers an overview of the studies on the vitreous proteome that could help to elucidate some of the pathological mechanisms underlying proliferative and/or neovascular vitreoretinal diseases and to find new potential pharmaceutical targets.

Efficacy and safety of the dexamethasone implant in vitrectomized and nonvitrectomized eyes with diabetic macular edema: A systematic review and meta-analysis

Purpose: To compare the efficacy and safety of the intravitreal dexamethasone (DEX) implant for the treatment of diabetic macular edema (DME) in vitrectomized and nonvitrectomized eyes.

Methods: We performed a literature search in four electronic databases (PubMed, EMBASE, MEDLINE, and Cochrane Library) from inception to 22 May 2022. Studies comparing the efficacy of the DEX implant in vitrectomized and nonvitrectomized eyes with DME with at least 3 months of follow-up were included. The main outcomes included comparison of the mean change in the best-corrected visual acuity (BCVA) and central macular thickness (CMT) from baseline to different follow-up endpoints between the vitrectomized and nonvitrectomized groups. The secondary outcomes were the mean duration of action for the first DEX implantation and the number of required injections throughout the follow-up period. Safety data were collected and compared.

Results: The final analysis included 7 studies involving 582 eyes, 208 vitrectomized eyes and 374 nonvitrectomized eyes. The mean between-group differences in BCVA improvement were not significant at any endpoint, with averages difference of −0.07 logarithm of the minimum angle of resolution (logMAR) (p = 0.088) at 1 month, −0.03 logMAR (p = 0.472) 3 months, −0.07 logMAR (p = 0.066) 6 months, and −0.04 logMAR (p = 0.486) 12 months. The mean between-group differences in CMT reduction were not statistically significant, with mean differences of 7.17 μm (p = 0.685) at 1 month, 20.03 μm (p = 0.632) 3 months, −1.80 μm (p = 0.935) 6 months, and −25.65 μm (p = 0.542) 12 months. However, the vitrectomized group had a significantly shorter duration of action during the first DEX implantation than the nonvitrectomized group, with a mean difference of 0.8 months (p = 0.005). No significant between-group differences were detected for the number of required injections or safety profile.

Conclusion: This meta-analysis showed similar efficacy and safety of the sustained-release DEX intravitreal implant for vitrectomized and nonvitrectomized eyes with DME. The intravitreal DEX implant could be considered an effective choice for DME treatment in eyes with prior vitrectomy.

Sphingosine 1-phosphate, a potential target in neovascular retinal disease

Neovascular ocular diseases (such as age-related macular degeneration, diabetic retinopathy and retinal vein occlusion) are characterised by common pathological processes that contribute to disease progression. These include angiogenesis, oedema, inflammation, cell death and fibrosis. Currently available therapies target the effects of vascular endothelial growth factor (VEGF), the main mediator of pathological angiogenesis. Unfortunately, VEGF blockers are expensive biological therapeutics that necessitate frequent intravitreal administration and are associated with multiple adverse effects. Thus, alternative treatment options associated with fewer side effects are required for disease management. This review introduces sphingosine 1-phosphate (S1P) as a potential pharmacological target for the treatment of neovascular ocular pathologies. S1P is a sphingolipid mediator that controls cellular growth, differentiation, survival and death. S1P actions are mediated by five G protein-coupled receptors (S1P_1-5 receptors) which are abundantly expressed in all retinal and subretinal structures. The action of S1P on S1P₁ receptors can reduce angiogenesis, increase endothelium integrity, reduce photoreceptor apoptosis and protect the retina against neurodegeneration. Conversely, S1P₂ receptor signalling can increase neovascularisation, disrupt endothelial junctions, stimulate VEGF release, and induce retinal cell apoptosis and degeneration of neural retina. The aim of this review is to thoroughly discuss the role of S1P and its different receptor subtypes in angiogenesis, inflammation, apoptosis and fibrosis in order to determine which of these S1P-mediated processes may be targeted therapeutically.

Molecules related to diabetic retinopathy in the vitreous and involved pathways

Diabetic retinopathy (DR) is one of the most common complications of diabetes and major cause of blindness among people over 50 years old. Current studies showed that the vascular endothelial growth factor (VEGF) played a central role in the pathogenesis of DR, and application of anti-VEGF has been widely acknowledged in treatment of DR targeting retinal neovascularization. However, anti-VEGF therapy has several limitations such as drug resistance. It is essential to develop new drugs for future clinical practice. The vitreous takes up 80% of the whole globe volume and is in direct contact with the retina, making it possible to explore the pathogenesis of DR by studying related factors in the vitreous. This article reviewed recent studies on DR-related factors in the vitreous, elaborating the VEGF upstream hypoxia-inducible factor (HIF) pathway and downstream pathways phosphatidylinositol diphosphate (PIP2), phosphoinositide-3-kinase (PI3K), and mitogen-activated protein kinase (MAPK) pathways. Moreover, factors other than VEGF contributing to the pathogenesis of DR in the vitreous were also summarized, which included factors in four major systems, kallikrein-kinin system such as bradykinin, plasma kallikrein, and coagulation factor XII, oxidative stress system such as lipid peroxide, and superoxide dismutase, inflammation-related factors such as interleukin-1β/6/13/37, and interferon-γ, matrix metalloproteinase (MMP) system such as MMP-9/14. Additionally, we also introduced other DR-related factors such as adiponectin, certain specific amino acids, non-coding RNA and renin (pro) receptor in separate studies.

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.

Inflammatory cytokines and retinal nonperfusion area in quiescent proliferative diabetic retinopathy

PURPOSE

We sought to investigate the association between inflammatory cytokine levels and retinal capillary nonperfusion area in eyes with quiescent proliferative diabetic retinopathy (PDR).

METHODS

Samples of aqueous humor were collected from 67 eyes (n = 42 patients) with treatment-naïve PDR. Levels of interleukin (IL)-10, IL-1β, IL-6, IL-8, monocyte chemoattractant protein 1 (MCP-1), and tumor necrosis factor-α (TNF-α) were obtained using multiplex bead assay. Areas of capillary nonperfusion at the posterior pole and peripheral retina were measured via ultra-widefield fluorescein angiography and correlated with cytokine levels.

RESULTS

The levels of IL-10, IL-6, IL-8, MCP-1, and TNF-α were positively correlated with the nonperfusion area of the peripheral retina (r = 0.298, 0.401, 0.265, 0.435, and 0.393; all P ≤ 0.030). There were positive correlations between IL and 10, IL-6, IL-8, MCP-1, and TNF-α (all R ≥ 0.247; all P ≤ 0.043). IL-1β did not show a significant correlation with the nonperfusion area (P = 0.972 for posterior pole and 0.392 for periphery) but was positively correlated with TNF-α (r = 0.334; P = 0.006).

CONCLUSIONS

An increased level of inflammation was observed in PDR eyes with larger nonperfusion areas, which suggests inflammation as a possible target for suppressing PDR progression associated with nonperfusion.

Systemic and vitreous biomarkers - new insights in diabetic retinopathy

PURPOSE

Diabetic retinopathy (DR) is a microvascular inflammatory and neurodegenerative disease. The purpose of this study was to analyze the relationship between DR severity and the levels of potential biomarkers in the serum and/or vitreous.

METHODS

A prospective, consecutive, controlled, observational study was performed between June 2018 and January 2020. Blood and vitreous samples were collected on the day of vitrectomy in patients without diabetes and in patients with diabetes with epiretinal membrane, macular edema, and indication for vitrectomy.

RESULTS

Transthyretin (TTR) was the only blood biomarker with levels statistically higher in patients with diabetes (p = 0.037). However, no correlation with DR severity was observed. Erythropoietin (EPO) was the only blood biomarker whose levels were associated with DR severity (p = 0.036). In vitreous samples, levels of EPO (p = 0.011), interleukin (IL)-6 (p < 0.001), IL-8 (p < 0.001), IL-17 (p = 0.022), monokine induced by interferon-γ (MIG) (p < 0.001), and interferon gamma-induced protein 10 (IP-10) (p = 0.005) were significantly higher in patients with diabetes. Additionally, in vitreous, IL-6, IL-8, MIG, and IPL-10 levels were also higher in more severe DR cases (p < 0.05).

CONCLUSIONS

Among the studied biomarkers, vitreous IL-6, IL-8, MIG, and IP-10 were the ones whose levels had the strongest coherent relationship with DR severity prediction and, thus, have the best potential post-vitrectomy prognostic value.

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.

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

Diabetic macular oedema (DME) is considered a chronic inflammatory disease associated with aberrations in many intraocular cytokines. Studies assessing the role of these cytokines as biomarkers in the diagnosis and management of DME have demonstrated inconsistent findings. We quantitatively summarized data related to 116 candidate aqueous and vitreous inflammatory cytokines as biomarkers in DME. A systematic search without year limitation was performed up to 19 October 2020. Studies were included if they provided data on aqueous or vitreous cytokine concentrations in patients with DME. Effect sizes were generated as standardized mean differences (SMDs) of cytokine concentrations between patients with DME and controls. Data were extracted from 128 studies that included 4163 study eyes with DME and 1281 control eyes. Concentrations (standard mean difference, 95% confidence interval and p-value) of aqueous IL-6 (1.28, 0.57-2.00, p = 0.004), IL-8 (1.06, 0.74-1.39, p < 0.00001), MCP-1 (1.36, 0.57-2.16, p = 0.0008) and VEGF (1.31, 1.01-1.62, p < 0.00001) and vitreous VEGF (2.27, 1.55-2.99, p < 0.00001) were significantly higher in patients with DME (n = 4163) compared to healthy controls (n = 1281). No differences, failed sensitivity analyses or insufficient data were found between patients with DME and healthy controls for the concentrations of the remaining cytokines. This analysis implicates multiple cytokine biomarker candidates other than VEGF in DME and clarifies previously reported inconsistent associations. As the therapeutic options for DME expand to include multiple agents with multiple targets, it will be critical to manage the treatment burden with tailored therapy that optimizes outcomes and minimizes treatment burden. Intraocular cytokines have the promise of providing a robust individualized assessment of disease status and response to therapy. We have identified key candidate cytokines that may serve as biomarkers in individualized treatment algorithms.

Clinical Features and Vitreous Biomarkers of Early-Onset Type 2 Diabetes Mellitus Complicated with Proliferative Diabetic Retinopathy

PURPOSE

To compare the clinical features and vitreous biomarkers of proliferative diabetic retinopathy (PDR) between patients with early-onset and late-onset type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

This case-control study analyzed the clinical data of 74 patients with PDR who underwent vitrectomy. The patients were divided into the early-onset (T2DM diagnosis age ≤ 40 years, n = 39) and late-onset (T2DM diagnosis age > 40 years, n = 35) groups. Thirty-six specimens were collected, and the liquid chip technology was used to detect the content of 27 types of cytokines in the vitreous. Differences in clinical features and cytokine levels between the two groups were evaluated. Bonferroni correction was applied for multiple comparisons.

RESULTS

Compared with the late-onset group, the levels of hemoglobin A1c (HbA1c) and total cholesterol were significantly higher in the early-onset group (P < 0.001 and P = 0.009, respectively). Patients with early-onset T2DM PDR had worse visual prognoses and a higher rate of postoperative recurrent vitreous hemorrhage. The results of cytokine detection showed that the levels of interleukin-4 (IL-4), IL-6, IL-8, IL-9, granulocyte colony-stimulating factor, interferon-γ, interferon-inducible 10 kDa, monocyte chemotactic protein 1, macrophage inflammatory protein (MIP)-1α, and MIP-1β in the early-onset group were significantly higher than those in the late-onset group (p < 0.0026). Age at diabetes diagnosis and HbA1c, IL-4, and regulated upon activation, normal T cell expressed and secreted levels were independent risk factors for visual acuity after undergoing vitrectomy.

CONCLUSION

Early-onset T2DM PDR patients had poor blood glucose and lipid metabolism, higher levels of inflammatory factors, and worse visual prognosis. Stricter metabolic management and earlier anti-inflammatory interventions may be required for patients with early-onset T2DM.

Comparison of Inflammatory and Angiogenic Factors in the Aqueous Humor of Vitrectomized and Non-Vitrectomized Eyes in Diabetic Macular Edema Patients

Objectives: To compare the aqueous concentrations of inflammatory and angiogenetic factors in vitrectomized vs. non-vitrectomized eyes with diabetic macular edema (DME).

Methods: Aqueous samples were obtained from 107 eyes with DME before intravitreal injection of anti-VEGF, 36 eyes with previous pars plana vitrectomy (PPV) combined with pan-retinal endolaser photocoagulation (PRP), and 71 treatment-naïve. Interleukin (IL)-6, IL-8, interferon-induced protein (IP)-10, monocyte chemoattractant protein (MCP)-1, and vascular endothelial growth factor (VEGF) were measured by cytometric bead array (CBA). Optical coherence tomography (OCT) was used for measuring central retinal thickness (CRT).

Results: IL-6, IL-8, IP-10, and MCP-1 in aqueous humor of DME vitrectomized eyes were significantly higher than in non-vitrectomized DME eyes, while VEGF was lower than in non-vitrectomized DME eyes. VEGF in aqueous humor significantly correlated with CRT for DME in non-vitrectomized DME eyes. IL-6, IL-8, IP-10, and MCP-1 in aqueous humor were not significantly associated with VEGF for DME in vitrectomized eyes.

Conclusions: Inflammation might play an important role in the pathogenesis of DME in vitrectomized eyes. Moreover, inflammation might play a central role in the development of DME via the VEGF-independent pathway. Thus, anti-inflammatory therapy might be a strategy for DME in vitrectomized eyes.

Comparison of Intravitreal Dexamethasone Implant and Ranibizumab in Vitrectomized Eyes with Diabetic Macular Edema

Purpose

This retrospective study aimed to compare the efficacy of intravitreal ranibizumab (IVR) and intravitreal dexamethasone implant (IDI) for pseudophakic vitrectomized eyes with diabetic macular edema (DME) in a single institution.

Methods

Pseudophakic vitrectomized eyes with treatment-naïve center-involved DME were enrolled, with one eye in each patient. They were divided into two groups: one group receiving IDI every 3 to 4 months and another group receiving IVR using 3 monthly plus treat-and-extend injections, all with monthly follow-up for 6 months. Switch of intravitreal drugs or deferred macular laser was not allowed. Primary outcome measures included change in central foveal thickness (CFT) in 1 mm by spectral-domain optical coherence tomography and best-corrected visual acuity (BCVA) at Month 6.

Results

Twenty-two eyes were included in the IDI group and 26 eyes in the IVR group. The baseline demographics, glycosylated hemoglobin level, intraocular pressure (IOP), BCVA, and CFT did not significantly differ (p > 0.05). Compared to baseline data, CFT decreased and BCVA improved significantly after either IDI or IVR at Month 6 (p < 0.05). Significantly better mean final BCVA (0.38 logMAR vs. 0.62 logMAR, p=0.04), more mean visual gain (−0.30 logMAR vs. −0.15 logMAR, p=0.02), lower mean final CFT (310.9 μm vs. 384.2 μm, p=0.04), and larger mean CFT decrease (−150.0 μm vs. −60.1 μm, p=0.03) were found in the IDI group compared to those in the IVR group. A smaller mean treatment number (2.6 vs. 5.6, p < 0.001) and higher rate of postinjection ocular hypertension requiring topical hypotensive agent therapy (27.3% vs. 0%, p=0.0002) were demonstrated in the IDI group than those in the IVR group.

Conclusion

We concluded that IDI and IVR can both effectively treat vitrectomized eyes with DME. Dexamethasone implants had significantly better visual/anatomical improvement, smaller treatment number, and higher rate of elevated IOP after injection than IVR in pseudophakic vitrectomized eyes with DME in a 6-month period.

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.

Dynamic monocyte chemoattractant protein-1 level as predictors of perceived pain during first and second phacoemulsification eye surgeries in patients with bilateral cataract

Background

The purpose of the study was to investigate whether dynamic monocyte chemoattractant protein-1 (MCP-1) level might be as predictors of perceived pain during the first and second phacoemulsification eye surgeries in patients with bilateral cataract.

Methods

Consecutive bilateral cataract patients undergoing bilateral sequential phacoemulsification were retrospectively enrolled. Patients’ preoperative anxiety score and intraoperative pain score were registered. Aqueous humor samples were obtained during surgery. MCP-1 level in the aqueous humor was measured by enzyme linked immunosorbent assay (Elisa). Patients were assigned to seven subgroups based on the interval between first-eye and second-eye cataract surgery. Comparisons were performed for a subjective sensation and MCP-1 levels among different subgroups.

Results

pain score during second-eye surgery was significantly higher than during first-eye surgery. Whereas there was no statistical difference in anxiety score between both surgeries. Result from subgroups comparison showed that the visual analog scale (VAS) pain score was statistically greater in 1-group and 6-group during the second eye surgery. Anxiety score did not statistically differ in subgroups. Additionally, the second-eye MCP-1 level was significantly higher at week 1and 6 intervals. Preoperative MCP-1 level was positively correlated with perceiving pain score during both surgeries.

Conclusions

MCP-1 level in aqueous humor significantly correlated with perceived pain during cataract surgery. Dynamic MCP-1 level could function as predictors of perceived pain during the first and second phacoemulsification eye surgeries in patients with bilateral cataract, which might support clinicians in treatment optimization and clinical decision-making.

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.

Retinal Microcirculation and Cytokines as Predictors for Recurrence of Macular Edema after Intravitreal Ranibizumab Injection in Branch Retinal Vein Occlusion

Purpose: To investigate the relationship between retinal blood flow, presence or absence of recurrence of macular edema, and levels of cytokines, after intravitreal ranibizumab injection (IRI) in patients with branch retinal vein occlusion (BRVO). Methods: In 47 patients with BRVO and macular edema, we used laser speckle flowgraphy (LSFG) to measure the relative flow volume (RFV) of the retinal arteries and veins passing through the optic disc in the occluded and non-occluded regions of the retina before and after IRI. Aqueous humor samples were obtained at the time of IRI. Levels of vascular endothelial growth factor (VEGF), soluble VEGF receptor (sVEGFR)-1, sVEGFR-2, placental growth factor (PlGF), platelet-derived growth factor (PDGF)-AA, soluble intercellular adhesion molecule (sICAM)-1, monocyte chemoattractant protein 1 (MCP-1), interleukin (IL)-6, IL-8, IL-12 (p70), IL-13 and interferon-inducible 10-kDa protein (IP-10) were measured by the suspension array method. Patients were categorized into two groups on the basis of whether or not macular edema recurred at 2 months after IRI: the nonrecurrent group, n = 24; and the recurrent group, n = 23. Results: In the veins of the occluded region, RFV showed a significant difference between baseline and 1 month after IRI (p < 0.001) in the recurrent group and the percent change of RFV showed a significant difference between the recurrent and nonrecurrent groups (p = 0.005). Furthermore, we found a significant negative correlation between RFV in the veins of the occluded region and aqueous levels of MCP-1, IL-8 and IP-10 at baseline (p = 0.029, p = 0.035, and p = 0.039, respectively). In the recurrent group, the arteries and veins of the non-occluded and occluded regions showed no significant association between RFV and the aqueous levels of any factors. Conclusions: These findings suggested that a decrease in RFV in the veins of the occluded region might be associated with the recurrence of macular edema and that the recurrence might depend on the change in RFV in the veins of the occluded region rather than the levels of cytokines.

The association of interieukin-6 polymorphism (rs1800795) with microvascular complications in Type 2 diabetes mellitus

Objectives: To evaluate the effects of the single-nucleotide polymorphism (SNP) rs1800795 in interieukin-6 (IL-6) gene on diabetic microvascular complications of Type 2 diabetes mellitus (T2DM), using statistical meta-analysis.

Methods: Literature pertaining to the relationship between the SNP rs1800795 and microvascular complications of T2DM including diabetic retinopathy, diabetic nephropathy, diabetic neuropathy and foot disease was retrieved from PubMed, Web of Science Knowledge and SinoMed databases. Original information was analyzed using Stata 12.0, including meta-analysis statistics, test for heterogeneity, evaluation of publication bias and sensitivity. Subgroup analysis was conducted to assess the effect of specific factors on the corresponding results.

Results: In total, 14 eligible articles were obtained. The SNP rs1800795 in IL-6 gene is not correlated with risk of microvascular complications in T2DM. Among the original literature, a genetic model (OR = 1.071, 95% CI: 0.681–1.685, P=0.767), an allelic genetic model (OR = 1.010, 95% CI: 0.959–1.063, P=0.703), a heterozygote genetic model (OR = 1.107, 95% CI: 0.916–1.339, P=0.292), a dominant genetic model (OR = 1.108, 95% CI: 0.885–1.387, P=0.372), and a recessive genetic model (OR = 0.978, 95% CI: 0.646–1.478, P=0.917) were included respectively. In the subgroup analysis by types of diabetic microvascular complications, we found no correlation between the SNP rs1000795 polymorphism and complications of T2DM in either the homozygote genetic model or the allelic genetic model (P<0.05).

Conclusion: Our results demonstrate that rs1800795 polymorphism in IL-6 gene is not correlated with the susceptibility of microvascular complications of T2DM.

The role of IL-6-174 G/C polymorphism and intraocular IL-6 levels in the pathogenesis of ocular diseases: a systematic review and meta-analysis

Interleukin-6 (IL-6) is one of the key regulators behind the inflammatory and pathological process associated with ophthalmic diseases. The role of IL-6-174 G/C polymorphism as well as intraocular IL-6 levels among various eye disease patients differ across studies and has not been systematically reviewed. Thus, this study aims to provide a summary to understand the relationship between IL-6 and ophthalmic disease. In total, 8,252 and 11,014 subjects for IL-6-174 G/C and intraocular levels of IL-6, respectively, were retrieved from PubMed, Scopus and Web of Science. No association was found between IL-6-174 G/C polymorphisms with ocular diseases. Subgroup analyses revealed a suggestive association between the GC genotype of IL-6-174 G/C with proliferative diabetic retinopathy (PDR). Further, the level of intraocular IL-6 among ocular disease patients in general was found to be higher than the control group [standardized mean difference (SMD) = 1.41, 95% confidence interval (CI) 1.24-1.58, P < 0.00001]. Closer examination through subgroup analyses yielded similar results in several ocular diseases. This study thus indicates that the IL-6-174 G/C polymorphism does not predispose patients to ocular disease, although the GC genotype is likely to be a genetic biomarker for PDR. Moreover, intraocular IL-6 concentrations are related to the specific manifestations of the ophthalmic diseases. Further studies with larger sample sizes are warranted to confirm this conclusion.

Comparative Analysis of Multiplex Platforms for Detecting Vitreous Biomarkers in Diabetic Retinopathy

Purpose

To evaluate the feasibility of using the Proximity Extension Assay (PEA) platform to detect biomarkers in vitreous and to compare the findings with results obtained with an electrochemiluminescent (ECL) sandwich immunoassay.

Methods

Vitreous samples from patients with proliferative diabetic retinopathy (PDR) and non-diabetic controls were tested using two different proteomics platforms. Forty-one assays were completed with the ECL platform and 459 with the PEA platform. Spearman's rank correlation coefficient (r_s) was used to determine the direction and strength of the relationship between protein levels detected by both platforms.

Results

Three hundred sixty-six PEA assays detected the tested protein in at least 25% of samples, and the difference in protein abundance between PDR and controls was statistically significant for 262 assays. Seventeen ECL assays yielded a detection rate ≥ 25%, and the difference in protein concentration between PDR and controls was statistically significant for 13 proteins. There was a subset of proteins that were detected by both platforms, and for those the Spearman's correlation coefficient was higher than 0.8.

Conclusions

PEA is suitable for the analysis of vitreous samples, showing a strong correlation with the ECL platform. The detection rate of PEA panels was higher than the panels tested with ECL. The levels of several proinflammatory and angiogenic cytokines were significantly higher in PDR vitreous compared to controls.

Translational Relevance

This study provides new information on the yields of small-volume assays that can detect proteins of interest in ocular specimens, and it identifies patterns of cytokine dysregulation in PDR.

Effect of dexamethasone intravitreal implant in vitrectomized and nonvitrectomized eyes of Taiwanese patients with treatment-naïve diabetic macular edema

BACKGROUND/PURPOSE

Vitrectomy may affect intravitreal drug clearance and efficacy for treating diabetic macular edema (DME). This study aimed to evaluate functional and anatomical outcomes of intravitreal dexamethasone (DEX) implant for vitrectomized and nonvitrectomized eyes with treatment-naïve DME in Taiwanese patients.

METHODS

In this retrospective single-center study, we reviewed treatment-naïve patients who received DEX implant monotherapy for center-involved DME from January 2015 to May 2017. Retreatments were provided at least 4 months apart as needed. The primary outcomes included changes from baseline in best-corrected visual acuity (BCVA) and central foveal thickness (CFT) at Month 6. Adverse events were recorded.

RESULTS

Twenty-seven eyes in 27 patients had prior vitrectomy and 43 eyes in 41 patients without vitrectomy. Baseline data were comparable. Overall, the improvements in BCVA and CFT were significant by 1 month post-treatment and sustained throughout the study (all p < 0.05). At Month 6, BCVA improved by 16.5 and 12.1 letters, and CFT reduced by 138.0 and 121.9 μm in vitrectomized and nonvitrectomized eyes, respectively, with a mean of 1.5 DEX implant injection. No significant differences in clinical outcomes were seen between the two groups (all p > 0.05). DEX implant injection was well tolerated. About 30% of patients had post-injection intraocular pressure value > 20 mmHg, and all were manageable with topical hypotensive agents, and no serious ocular complication was observed.

CONCLUSION

In this 6-month retrospective study, intravitreal DEX implant was effective in Taiwanese patients with treatment-naïve DME regardless of vitrectomy status.

Interleukin-6 and Diabetic Retinopathy: A Systematic Review and Meta-Analysis

BACKGROUND

Interleukin-6 (IL-6) is produced by a variety of cells involved in inflammation and acts as local intensification signals in pathological processes associated with chronic eye inflammation. This meta-analysis was performed to provide a better understanding of the relationship between IL-6 and diabetic retinopathy.

METHODS

The study was started with systematic search for literatures by using the PubMed, Web of Science and Embase online databases. The standard mean difference (SMD) and its 95% confidence intervals (CIs) were was included and then pooled with a random effects model.

RESULTS

Thirty-one articles, containing1099 DR patients and 1010 controls, were included in this meta-analysis. The level of IL-6 in the DR group was found to be higher than that in the control group (SMD: 2.12, 95% CI: 1.53-2.70, p < 0.00001).Obvious heterogeneity existed between the studies (p < 0.00001, I² = 96%). So a subgroup analysis and sensitivity analysis were performed. Removing the sensitivity studies, the stability of the overall treatment effect was good. Subgroup analysis showed that the levels of IL-6 in case group were observed to be higher than those in the control group; and the IL-6 levels in the proliferative diabetic retinopathy (PDR) group were also higher than those in the non-proliferative diabetic retinopathy (NPDR) group. (SMD: 0.78, 95% CI: 0.26-1.31, p=  0.003) Conclusion: The results from this current meta-analysis indicated that increased level of IL-6 generally exist in DR patients. And it may associated with the severity of DR. However, large-scale and high-quality studies in future are required to confirm the present findings.

Monocyte chemoattractant protein-1 (MCP-1/CCL2) in diabetic retinopathy: latest evidence and clinical considerations

Diabetic retinopathy (DR) is considered as a diabetes-related complication that can render severe visual impairments and is also a risk factor for acquired blindness in both developed as well as developing countries. Through fibrovascular epiretinal membranes (ERMs), this condition can similarly lead to tractional retinal detachment. Laboratory efforts evaluating the DR pathogenesis can be provided by ocular vitreous fluid and ERMs resulting from vitrectomy. The clinical stages of DR are significantly associated with expression levels of certain chemokines, including monocyte chemotactic protein-1 (MCP-1) in the intraocular fluid. The MCP-1 is also a known potent chemotactic factor for monocytes and macrophages that can stimulate them to produce superoxide and other mediators. Following hyperglycemia, retinal pigmented epithelial (RPE) cells, endothelial cells, and Müller's glial cells are of utmost importance for MCP-1 production, and vitreous MCP-1 levels rise in patients with DR. Increased expression of the MCP-1 in the eyes can also play a significant role in the pathogenesis of DR. In this review, current clinical and laboratory progress achieved on the MCP-1 and the DR concerning neovascularization and inflammatory responses in vitreous and/or aqueous humor of DR patients was summarized. It was suggested that further exploration of the MCP-1/CCR2 axis association between clinical stages of DR and expression levels of inflammatory and angiogenic cytokines and chemokines, principally the MCP-1 might lead to potential therapies aiming at neutralizing antibodies and viral vectors.

Risk factors for neovascular glaucoma after vitrectomy in eyes with proliferative diabetic retinopathy

Purpose

To investigate the potential risk factors for neovascular glaucoma (NVG) after vitrectomy in eyes with proliferative diabetic retinopathy.

Subjects and methods

In this retrospective, observational, comparative study, patients with proliferative diabetic retinopathy who underwent vitrectomy at Toho University Sakura Medical Center between December 2011 and November 2016 and who were followed for ≥12 months after surgery were included. Subject parameters examined included age, glycated hemoglobin (HbA1c), fasting blood glucose, administration of insulin, and estimated glomerular filtration rate. Ocular parameters examined included preoperative best-corrected visual acuity, preoperative IOP, operative history (specifically panretinal photocoagulation), lens status, ocular pathology (eg, iris/angle neovascularization, tractional retinal detachment, diabetic macular edema, vitreous hemorrhage, combined tractional retinal detachment), intraoperative retinal tamponade use, vitrectomy gauge, combined lens extraction/vitrectomy procedure, subsequent surgical procedures, and pre- and postoperative intravitreal bevacizumab. Correlations between variables and postoperative NVG development were examined using logistic regression analyses (backward elimination method).

Results

A total of 254 eyes of 196 consecutive subjects (146 men [74.5%], 54.0±10.8 years old) were included. Sixty of 254 eyes (23.6%) developed NVG. Several preoperative factors increased the risk of developing NVG, including iris/angle neovascularization (P=0.042), preoperative high IOP (P=0.005), low HbA1c (P=0.004), and administration of insulin (P=0.045). Intraoperative retinal tamponade also increased NVG risk (P=0.021, backward elimination method).

Conclusion

Preoperative parameters such as elevated IOP, iris/angle neovascularization, fasting blood sugar and HbA1c discrepancies, administration of insulin, as well as use of retinal tamponade during retinal surgery were identified as the risk factors for developing NVG.

Nepetin inhibits IL-1β induced inflammation via NF-κB and MAPKs signaling pathways in ARPE-19 cells

BACKGROUNDS

Chronic inflammation in retinal pigment epithelial (RPE) cells is related to the pathogenesis of retinal inflammatory blind causing diseases such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Nepetin, a natural flavonoid compound, has shown potent anti-inflammatory activities but has not been studied on ocular resident cells yet. Here, we assess the ability of Nepetin to alleviate the inflammatory responses of ARPE-19 cells induced by interleukin (IL)-1β.

METHODS

The secretion and mRNA expression of inflammatory cytokines IL-6, IL-8 and monocyte chemoattractant protein-1 (MCP-1) induced by IL-1β are measured by enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR) respectively. To clarify the underlying action mechanism, we examine the effect of Nepetin on activation of nuclear factor of kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways using Western blot.

RESULTS

Nepetin can significantly decrease the three inflammatory mediators at both protein and mRNA level in a dose-dependent manner. Western blot results show that Nepetin can decrease the nuclear translocation of p65 through suppressing phosphorylation of inhibitor of nuclear factor kappa B (IκB) and IκB kinase (IKK). Also, Nepetin can decrease the phosphorylation of extracellular signal-regulated kinases (ERK) 1/2, c-Jun N-terminal kinase (JNK) and p38 MAPK.

CONCLUSIONS

Taken together, Nepetin abolishes IL-1β-induced IL-6, IL-8 and MCP-1 secretion and mRNA expression by repressing the activation of NF-κB and MAPKs. These results indicate that Nepetin shows potential to be used for prevention and treatment of inflammatory retinal diseases or as a lead compound.

Effect of intravitreal triamcinolone acetonide injection at the end of vitrectomy for vitreous haemorrhage related to proliferative diabetic retinopathy

Background/Aims

To investigate whether intravitreal injection of triamcinolone acetonide (IVTA) combined with vitrectomy prevents postoperative inflammation in patients with vitreous haemorrhage (VH) due to proliferative diabetic retinopathy (PDR).

Methods

This prospective, multicentre, randomised study conducted at seven sites in Japan enrolled patients diagnosed as having VH following PDR. Patients underwent vitrectomy with (IVTA+VIT group) or without (VIT group) IVTA at the end of the surgery. Anterior flare intensity (AFI), central retinal thickness (CRT), best-corrected visual acuity (BCVA) and intraocular pressure (IOP) were measured before and at 3 days, 1 week, 1, 3 and 6 months after surgery and compared.

Results

Number of patients who completed 6 months of follow-up was 40 and 41 in VIT group and IVTA+VIT group, respectively. AFI was significantly higher in the VIT group than in the IVTA+VIT group at 3 days (P=0.033), 1 week (P=0.019) and 1 month (P=0.037). There were no significant differences in CRT, BCVA and IOP between the groups through the observational periods. In the cases with macular oedema >350 µm of CRT at 3 days, CRT was significantly lower in the IVTA+VIT group than in the VIT group at 1 month (P=0.041).

Conclusions

IVTA combined with vitrectomy and cataract surgery contributed to inhibit the postoperative inflammation in patients with VH due to PDR. The effect of IVTA in the reduction of diabetic macular oedema may be limited to the early stage after surgery.

Trial registration number

UMIN000020376, Post-results.

Management of diabetic macular edema in Japan: a review and expert opinion

Diabetic retinopathy is a frequent cause of visual impairment in working-age adults (≥ 30 years) and in Japan is most commonly observed in those aged 50-69 years. Diabetic macular edema (DME) is one of the main causes of vision disturbance in diabetic retinopathy, which is a clinically significant microvascular complication of diabetes. Anti-vascular endothelial growth factor (VEGF) therapy is becoming the mainstay of treatment for DME. However, to achieve sustained long-term improvement in visual acuity, conventional laser photocoagulation, vitrectomy and steroid therapy are also expected to play a role in the treatment of DME. This review summarizes the epidemiology and pathology of diabetic retinopathy and DME, evaluates the findings regarding the diagnosis and treatment of DME, and underscores the importance of systemic management of the disease in the context of the current health care situation in Japan. Finally, the unmet needs of patients with DME and prospects for research are discussed. The weight of evidence suggests that it is important to establish a multipronged treatment strategy centered on anti-VEGF therapy.

Periostin in vitreoretinal diseases

Proliferative vitreoretinal diseases such as diabetic retinopathy, proliferative vitreoretinopathy (PVR), and age-related macular degeneration are a leading cause of decreased vision and blindness in developed countries. In these diseases, retinal fibro(vascular) membrane (FVM) formation above and beneath the retina plays an important role. Gene expression profiling of human FVMs revealed significant upregulation of periostin. Subsequent analyses demonstrated increased periostin expression in the vitreous of patients with both proliferative diabetic retinopathy and PVR. Immunohistochemical analysis showed co-localization of periostin with α-SMA and M2 macrophage markers in FVMs. In vitro, periostin blockade inhibited migration and adhesion induced by PVR vitreous and transforming growth factor-β2 (TGF-β2). In vivo, a novel single-stranded RNAi agent targeting periostin showed the inhibitory effect on experimental retinal and choroidal FVM formation without affecting the viability of retinal cells. These results indicated that periostin is a pivotal molecule for FVM formation and a promising therapeutic target for these proliferative vitreoretinal diseases.

Differential association of elevated inflammatory cytokines with postoperative fibrous proliferation and neovascularization after unsuccessful vitrectomy in eyes with proliferative diabetic retinopathy

BACKGROUND

Pars plana vitrectomy is the only treatment for advanced proliferative diabetic retinopathy (PDR). However, vitrectomy is not always successful despite current progress in vitreoretinal surgical techniques. The aim of our study was to investigate whether the vitreal concentrations of MCP-1, IL-6, IL-8, and VEGF are elevated after unsuccessful vitrectomy in patients with PDR and to investigate whether the altered levels of these cytokines are associated with the cause for the reoperation.

PATIENTS AND METHODS

Vitreous samples were collected from 263 eyes of 233 patients: PDR (n=129 eyes), proliferative vitreoretinopathy (PVR; n=24 eyes) and nondiabetic controls (n=110 eyes) prior to vitrectomy. Vitreous samples were also collected from 14 eyes of 14 patients with PDR before vitrectomy and from the same 14 eyes before a second vitrectomy for reoperation. The levels of MCP-1, IL-6, IL-8, and VEGF were measured by flow cytometry using a cytometric bead array (CBA) assay.

RESULTS

The mean concentrations of vitreal MCP-1, IL-6, IL-8, and VEGF were significantly higher in patients with PDR and PVR (P<0.01). There were significantly high correlations among the concentrations of MCP-1, IL-6, and IL-8, whereas the correlation of VEGF with the other 3 cytokines was lower. Among the 14 patients who required reoperation, the mean vitreal concentrations of MCP-1, IL-6, and IL-8 were higher than that at the time of the initial vitrectomy (P<0.01). At the time of the reoperation vitrectomy, the mean vitreous level of MCP-1, IL-6, and IL-8 in eyes with fibrous proliferation was higher than in those without fibrous proliferation (P<0.05). In contrast, VEGF in eyes with neovascular glaucoma (NVG) or anterior hyaloidal fibrovascular proliferation (AHFVP) was higher than in the eyes without NVG and AHFVP (P<0.05).

CONCLUSION

The elevated levels of MCP-1, IL-6, and IL-8 may be the cause of the postoperative fibrous proliferation. In contrast, VEGF may be the cause of the neovascularization after unsuccessful vitrectomy in the eyes of PDR patients.

Comparisons of Efficacy of Intravitreal Aflibercept and Ranibizumab in Eyes with Diabetic Macular Edema

We compared the efficacy of intravitreal aflibercept (IVA) to intravitreal ranibizumab (IVR) injections in eyes with diabetic macular edema (DME). The medical records of 49 eyes of 36 patients who were diagnosed with DME and had received IVR and 46 eyes of 40 patients who had received IVA treatment were reviewed. The central macular thickness (CMT) and best-corrected visual acuity (BCVA) were measured at the baseline and at 1, 3, and 6 months after the IVR or IVA. The mean number of injections of IVR was 2.6 ± 1.1 and of IVA was 2.7 ± 1.4. At 6 months, the CMT was significantly thinner than the baseline after IVR and after IVA. The mean BCVA was significantly better than the baseline after IVR only at 1 and 3 months and after IVA at 1 and 6 months. The BCVA of eyes with serous retinal detachment (SRD) was significantly better at 1 month after the IVR and at 1 month and 6 months after the IVA. The BCVAs improved more significantly in the SRD+ group than in the SRD- group. The effects of IVA persist longer than that of IVR. The effectiveness of both IVR and IVA was not dependent on the presence of SRD (IRB#2107).

Correlation between Interleukin-6 and Thrombin-Antithrombin III Complex Levels in Retinal Diseases

PURPOSE

This study aims to evaluate and correlate the levels of interleukin-6 (IL-6) and thrombin-antithrombin III complex (TAT) in the vitreous of patients with different vitreoretinal pathologies.

METHODS

Vitreous samples were collected from 78 patients scheduled for pars plana vitrectomy at a tertiary medical center. Patients were divided by the underlying vitreoretinal pathophysiology, as follows: macular hole (MH)/epiretinal membrane (ERM) (n = 26); rhegmatogenous retinal detachment (RRD) (n = 32); and proliferative diabetic retinopathy (PDR) (n = 20). Levels of IL-6 and TAT were measured by enzyme-linked immunosorbent assay and compared among the groups.

RESULTS

A significant difference was found in the vitreal IL-6 and TAT levels between the MH/ERM group and both the PDR and RRD groups (P < 0.001 for all). Diabetes was associated with higher IL-6 levels in the RRD group. Different relationships between the IL-6 and TAT levels were revealed in patients with different ocular pathologies.

CONCLUSION

Our results imply that variations in vitreal TAT level may be attributable not only to an inflammatory reaction or blood-retinal barrier breakdown, but also to intraocular tissue-dependent regulation of thrombin.

Safety and Feasibility of Quantitative Multiplexed Cytokine Analysis From Office-Based Vitreous Aspiration

Purpose

The goals of this study were to evaluate the safety of office-based vitreous sampling, and determine the utility of these samples with multiplex cytokine analysis.

Methods

Vitreous samples were collected from office-based needle aspiration and the rate of adverse events during follow-up was reviewed. The vitreous cytokine concentrations in a subset of patients with diabetic macular edema (DME) were analyzed using a 42 plex-cytokine bead array. These results were compared with vitreous cytokine concentrations in proliferative diabetic retinopathy (PDR) and controls (macular hole, epiretinal membrane, symptomatic vitreous floaters) from pars plana vitrectomy.

Results

An adequate volume of vitreous fluid (100–200 μL) was obtained in 52 (88%) of 59 office-based sampling attempts. The average length of follow-up was 300 days (range, 42–926 days). There were no complications, including cataract, retinal tear or detachment, and endophthalmitis. Two patients (3%) had posterior vitreous detachments within 3 months. Vitreous cytokine concentrations were measured in 44 patients: 14 controls, 13 with DME, and 17 with PDR. The concentration of ADAM11, CXCL-10, IL-8, and PDGF-A were higher in PDR compared with controls and DME. The concentration of IL-6 was higher in PDR compared with controls, but not compared with DME.

Conclusions

Office-based vitreous aspiration is safe and yields high-quality samples for multiplex vitreous cytokine analysis. Significant elevations of vitreous cytokines were found in PDR compared with DME and controls, including the novel finding of elevated ADAM11. As such, office-based aspiration is a safe and effective means to identify vitreous factors associated with vitreoretinal disease.

miR-146a suppresses STAT3/VEGF pathways and reduces apoptosis through IL-6 signaling in primary human retinal microvascular endothelial cells in high glucose conditions

microRNA (miRNA) play critical roles in the pathological processes of diabetic retinopathy, including inflammatory responses, insulin signaling, and angiogenesis. In addition to their regulatory functions on gene expression, miRNA is considered as a potential therapeutic target, as well as a diagnostic marker for many diseases. Our understanding on the pathological mechanisms underlying diabetic retinopathy is still incomplete and additional investigations are required to develop novel therapeutic strategies. The aim of this study was to investigate our hypothesis that miR-146a plays a role in suppressing pro-inflammatory pathways, involving STAT3 and VEGF, through regulating IL-6 signaling to reduce apoptosis of human retinal endothelial cells (REC) in high glucose conditions. Human REC were cultured in normal (5mM) glucose or high glucose medium (25mM) for 3days. We performed transfections on REC with miRNA mimics (hsa-miR-146a-5p). Overexpression of miR-146a reduced IL-6 levels, STAT3 phosphorylation, and VEGF levels in REC cultured in high glucose. Cellular apoptosis was decreased in REC overexpressing miR-146a, as demonstrated by the inhibition of DNA fragmentation. More importantly, we demonstrated that the regulatory role of miR-146a on STAT3/VEGF and apoptosis was mediated by IL-6 receptor signaling in REC. Overall, we report that miR-146a suppressed IL-6 signaling, leading to reduced levels of STAT3 and VEGF in REC in high glucose conditions, leading to decreased apoptosis. The outcome suggests that miR-146a is a potential molecular target for inhibiting inflammation and apoptosis in the diabetic retina through the suppression of the IL-6-mediated STAT3/VEGF pathway.

Oxidative Stress-Related Mechanisms and Antioxidant Therapy in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and is the leading cause of blindness in young adults. Oxidative stress has been implicated as a critical cause of DR. Metabolic abnormalities induced by high-glucose levels are involved in the development of DR and appear to be influenced by oxidative stress. The imbalance between reactive oxygen species (ROS) production and the antioxidant defense system activates several oxidative stress-related mechanisms that promote the pathogenesis of DR. The damage caused by oxidative stress persists for a considerable time, even after the blood glucose concentration has returned to a normal level. Animal experiments have proved that the use of antioxidants is a beneficial therapeutic strategy for the treatment of DR, but more data are required from clinical trials. The aims of this review are to highlight the improvements to our understanding of the oxidative stress-related mechanisms underlying the development of DR and provide a summary of the main antioxidant therapy strategies used to treat the disease.

Comparison of the Effectiveness of Intravitreal Ranibizumab for Diabetic Macular Edema in Vitrectomized and Nonvitrectomized Eyes

PURPOSE

To compare the effectiveness of intravitreal ranibizumab (IVR) for diabetic macular edema (DME) between eyes with and without previous vitrectomy.

PROCEDURES

We prospectively assessed the best-corrected visual acuity (BCVA) and central macular thickness (CMT) after IVR for 6 months.

RESULTS

There were no significant differences in the baseline BCVA and CMT between both groups. In the nonvitrectomized group (n = 15), the mean changes of BCVA and CMT from baseline to month 6 were significant (p < 0.01). In the vitrectomized group (n = 10), the improvement appeared to be slower, and the mean BCVA improvement was not significant (p = 0.5), although the mean CMT decrease was significant (p < 0.05). There were no significant differences in the mean changes of BCVA and CMT between both groups at 6 months.

CONCLUSIONS

The difference in the effectiveness of IVR between both groups was not significant. IVR can be a treatment option even for vitrectomized DME eyes.

Small Interfering RNA Targeted to ASPP2 Promotes Progression of Experimental Proliferative Vitreoretinopathy

Background. Epithelial-mesenchymal transition (EMT) of retinal pigment epithelium (RPE) is vital in proliferative vitreoretinopathy (PVR) development. Apoptosis-stimulating proteins of p53 (ASPP2) have recently been reported to participate in EMT. However, the role of ASPP2 in PVR pathogenesis has not been identified. Methods. Immunohistochemistry was used to investigate the expression of ASPP2 in epiretinal membranes of PVR patients. ARPE-19 cells were transfected with ASPP2-siRNA, followed with measurement of cell cytotoxicity, proliferation, and migration ability. EMT markers and related inflammatory and fibrosis cytokines were measured by western blot or flow cytometry. Additionally, PVR rat models were induced by intravitreal injection of ARPE-19 cells transfected with ASPP2-siRNA and evaluated accordingly. Results. Immunofluorescence analysis revealed less intense expression of ASPP2 in PVR membranes. ASPP2 knockdown facilitated the proliferation and migration of RPE cells and enhanced the expression of mesenchymal markers such as alpha smooth muscle actin, fibronectin, and ZEB1. Meanwhile, ASPP2-siRNA increased EMT-related and inflammatory cytokines, including TGF-β, CTGF, VEGF, TNF-α, and interleukins. PVR severities were more pronounced in the rat models with ASPP2-siRNA treatment. Conclusions. ASPP2 knockdown promoted EMT of ARPE-19 cells in vitro and exacerbated the progression of experimental PVR in vivo, possibly via inflammatory and fibrosis cytokines.

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.

The Neuroprotective Effect of Rapamycin as a Modulator of the mTOR-NF-κB Axis during Retinal Inflammation

Purpose

The determination of the molecular mechanism underlying retinal pathogenesis and visual dysfunction during innate inflammation, and the treatment effect of rapamycin thereon.

Methods

The endotoxin-induced uveitis and retinitis mouse model was established by injecting lipopolysaccharide. The mice were subsequently treated with rapamycin, a mammalian target of rapamycin (mTOR) inhibitor. The rhodopsin mRNA and protein expression level in the retina and the photoreceptor outer segment (OS) length in immunohistochemical stainings were measured, and visual function was recorded by electroretinography. Inflammatory cytokines, their related molecules, mTOR, and LC3 levels were measured by real-time PCR and/or immunoblotting. Leukocyte adhesion during inflammation was analyzed using concanavalin A lectin.

Results

The post-transcriptional reduction in the visual pigment of rod photoreceptor cells, rhodopsin, OS shortening, and rod photoreceptor cell dysfunction during inflammation were suppressed by rapamycin. Activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and induction of inflammatory cytokines, such as interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), and the activation of the downstream signaling protein, signal transducer and activator of transcription 3 (STAT3), which reduces rhodopsin in the retina during inflammation, were attenuated by rapamycin. Increased leukocyte adhesion was also attenuated by rapamycin. Interestingly, although mTOR activation was observed after NF-κB activation, mTOR inhibition suppressed NF-κB activation at the early phase, indicating that the basal level of activated mTOR was sufficient to activate NF-κB in the retina. In addition, the inhibition of NF-κB suppressed mTOR activation, suggesting a positive feedback loop of mTOR and NF-κB during inflammation. The ratio of LC3II to LC3I, which reflects autophagy induction, was not changed by inflammation but was increased by rapamycin.

Conclusions

Our results propose the potential use of rapamycin as a neuroprotective therapy to suppress local activated mTOR levels, related inflammatory molecules, and the subsequent visual dysfunction during retinal inflammation.