SDF-1 is both necessary and sufficient to promote proliferative retinopathy

Cytokine Levels in Experimental Branch Retinal Vein Occlusion Treated With Either Bevacizumab or Triamcinolone Acetonide

Purpose

To compare gene expression changes following branch retinal vein occlusion (BRVO) in the pig with and without bevacizumab (BEV) and triamcinolone acetonide (TA).

Methods

Photothrombotic BRVOs were created in both eyes of four groups of nine pigs (2, 6, 10, and 20 days). In each group, six pigs received intravitreal injections of BEV in one eye and TA in the fellow eye, with three pigs serving as untreated BRVO controls. Three untreated pigs served as healthy controls. Expression of mRNA of vascular endothelial growth factor (VEGF), glial fibrillary acidic protein (GFAP), dystrophin (DMD), potassium inwardly rectifying channel subfamily J member 10 protein (Kir4.1, KCNJ10), aquaporin-4 (AQP4), stromal cell-derived factor-1α (CXCL12), interleukin-6 (IL6), interleukin-8 (IL8), monocyte chemoattractant protein-1 (CCL2), intercellular adhesion molecule 1 (ICAM1), and heat shock factor 1 (HSF1) were analyzed by quantitative reverse-transcription polymerase chain reaction. Retinal VEGF protein levels were characterized by immunohistochemistry.

Results

In untreated eyes, BRVO significantly increased expression of GFAP, IL8, CCL2, ICAM1, HSF1, and AQP4. Expression of VEGF, KCNJ10, and CXCL12 was significantly reduced by 6 days post-BRVO, with expression recovering to healthy control levels by day 20. Treatment with BEV or TA significantly increased VEGF, DMD, and IL6 expression compared with untreated BRVO eyes and suppressed BRVO-induced CCL2 and AQP4 upregulation, as well as recovery of KCNJ10 expression, at 10 to 20 days post-BRVO.

Conclusions

Inflammation and cellular osmohomeostasis rather than VEGF suppression appear to play important roles in BRVO-induced retinal neurodegeneration, enhanced in both BEV- and TA-treated retinas.

Translational Relevance

Inner retinal neurodegeneration seen in this acute model of BRVO appears to be mediated by inflammation and alterations in osmohomeostasis rather than VEGF inhibition, which may have implications for more specific treatment modalities in the acute phase of BRVO.

Erythropoiesis-Stimulating Agents and the Risk of Vision-Threatening Diabetic Retinopathy

PURPOSE

Animal studies have suggested that Erythropoiesis-Stimulating Agents (ESAs) may increase vascular endothelial growth factor (VEGF)-related retinopathies, but this effect is unclear in humans. This study evaluates the risk of vision-threatening diabetic retinopathy (VTDR), defined as either diabetic macular edema (DME) or proliferative diabetic retinopathy (PDR), in patients exposed to an ESA.

METHODS

Two analyses were performed. First, a retrospective matched-cohort study was designed using a de-identified commercial and Medicare Advantage medical claims database. The ESA cohort of non-proliferative diabetic retinopathy patients who were new users of an ESA from 2000 to 2022 was matched to controls up to a 3:1 ratio. Exclusion criteria included less than 2 years in the plan, history of VTDR or history of other retinopathy. Multivariable Cox proportional hazards regression with inverse proportional treatment weighting (IPTW) was used to assess the hazard of developing VTDR, DME, and PDR. The second analysis was a self-controlled case series (SCCS) evaluating the incidence rate ratios (IRR) of VTDR during 30-day periods before and after initiating an ESA.

RESULTS

After inclusion of 1502 ESA-exposed patients compared with 2656 controls, IPTW-adjusted hazard ratios found the ESA cohort had an increased hazard of progressing to VTDR (HR = 3.0 95%CI:2.3-3.8;p < .001) and DME (HR = 3.4,95%CI:2.6-4.4,p < .001), but not PDR (HR = 1.0,95%CI:0.5-2.3,p = .95). Similar results were found within the SCCS which demonstrated higher IRRs for VTDR (IRRs = 1.09-1.18;p < .001) and DME (IRRs = 1.16-1.18;p < .001), but not increased IRRs in PDR (IRR = 0.92-0.97,p = .02-0.39).

CONCLUSION

ESAs are associated with higher risks for VTDR and DME, but not PDR. Those studying ESAs as adjunctive therapy for DR should be cautious of possible unintended effects.

Incretins and microvascular complications of diabetes: neuropathy, nephropathy, retinopathy and microangiopathy

Glucagon-like peptide-1 receptor agonists (GLP-1RAs, incretin mimetics) and dipeptidyl peptidase-4 inhibitors (DPP-4is, incretin enhancers) are glucose-lowering therapies with proven cardiovascular safety, but their effect on microvascular disease is not fully understood. Both therapies increase GLP-1 receptor agonism, which is associated with attenuation of numerous pathological processes that may lead to microvascular benefits, including decreased reactive oxygen species (ROS) production, decreased inflammation and improved vascular function. DPP-4is also increase stromal cell-derived factor-1 (SDF-1), which is associated with neovascularisation and tissue repair. Rodent studies demonstrate several benefits of these agents in the prevention or reversal of nephropathy, retinopathy and neuropathy, but evidence from human populations is less clear. For nephropathy risk in human clinical trials, meta-analyses demonstrate that GLP-1RAs reduce the risk of a composite renal outcome (doubling of serum creatinine, eGFR reduction of 30%, end-stage renal disease or renal death), whereas the benefits of DPP-4is appear to be limited to reductions in the risk of albuminuria. The relationship between GLP-1RAs and retinopathy is less clear. Many large trials and meta-analyses show no effect, but an observed increase in the risk of retinopathy complications with semaglutide therapy (a GLP-1RA) in the SUSTAIN-6 trial warrants caution, particularly in individuals with baseline retinopathy. Similarly, DPP-4is are associated with increased retinopathy risk in both trials and meta-analysis. The association between GLP-1RAs and peripheral neuropathy is unclear due to little trial evidence. For DPP-4is, one trial and several observational studies show a reduced risk of peripheral neuropathy, with others reporting no effect. Evidence in other less-established microvascular outcomes, such as microvascular angina, cerebral small vessel disease, skeletal muscle microvascular disease and autonomic neuropathies (e.g. cardiac autonomic neuropathy, gastroparesis, erectile dysfunction), is sparse. In conclusion, GLP-1RAs are protective against nephropathy, whereas DPP-4is are protective against albuminuria and potentially peripheral neuropathy. Caution is advised with DPP-4is and semaglutide, particularly for patients with background retinopathy, due to increased risk of retinopathy. Well-designed trials powered for microvascular outcomes are needed to clarify associations of incretin therapies and microvascular diseases.

Novel Function of Nogo-A as Negative Regulator of Endothelial Progenitor Cell Angiogenic Activity: Impact in Oxygen-Induced Retinopathy

Endothelial Progenitor Cells (EPCs) can actively participate in revascularization in oxygen-induced retinopathy (OIR). Yet the mechanisms responsible for their dysfunction is unclear. Nogo-A, whose function is traditionally related to the inhibition of neurite function in the central nervous system, has recently been documented to display anti-angiogenic pro-repellent properties. Based on the significant impact of EPCs in retinal vascularization, we surmised that Nogo-A affects EPC function, and proceeded to investigate the role of Nogo-A on EPC function in OIR. The expression of Nogo-A and its specific receptor NgR1 was significantly increased in isolated EPCs exposed to hyperoxia, as well as in EPCs isolated from rats subjected to OIR compared with respective controls (EPCs exposed to normoxia). EPCs exposed to hyperoxia displayed reduced migratory and tubulogenic activity, associated with the suppressed expression of prominent EPC-recruitment factors SDF-1/CXCR4. The inhibition of Nogo-A (using a Nogo-66 neutralizing antagonist peptide) or siRNA-NGR1 in hyperoxia-exposed EPCs restored SDF-1/CXCR4 expression and, in turn, rescued the curtailed neovascular functions of EPCs in hyperoxia. The in vivo intraperitoneal injection of engineered EPCs (Nogo-A-inhibited or NgR1-suppressed) in OIR rats at P5 (prior to exposure to hyperoxia) prevented retinal and choroidal vaso-obliteration upon localization adjacent to vasculature; coherently, the inhibition of Nogo-A/NgR1 in EPCs enhanced the expression of key angiogenic factors VEGF, SDF-1, PDGF, and EPO in retina; CXCR4 knock-down abrogated suppressed NgR1 pro-angiogenic effects. The findings revealed that hyperoxia-induced EPC malfunction is mediated to a significant extent by Nogo-A/NgR1 signaling via CXCR4 suppression; the inhibition of Nogo-A in EPCs restores specific angiogenic growth factors in retina and the ensuing vascularization of the retina in an OIR model.

Inflammation: The Link between Neural and Vascular Impairment in the Diabetic Retina and Therapeutic Implications

The etiology of diabetic retinopathy (DR) is complex, multifactorial and compromises all the elements of the retinal neurovascular unit (NVU). This diabetic complication has a chronic low-grade inflammatory component involving multiple inflammatory mediators and adhesion molecules. The diabetic milieu promotes reactive gliosis, pro-inflammatory cytokine production and leukocyte recruitment, which contribute to the disruption of the blood retinal barrier. The understanding and the continuous research of the mechanisms behind the strong inflammatory component of the disease allows the design of new therapeutic strategies to address this unmet medical need. In this context, the aim of this review article is to recapitulate the latest research on the role of inflammation in DR and to discuss the efficacy of currently administered anti-inflammatory treatments and those still under development.

Novel characterization of CXCR4 expressing cells in uninfected and herpes simplex virus-1 infected corneas

PURPOSE

To characterize CXCR4-expressing cells in uninfected and herpes simplex virus-1 (HSV-1) infected corneas.

METHODS

The corneas of C57BL/6J mice were infected with HSV-1 McKrae. The RT-qPCR assay detected CXCR4 and CXCL12 transcripts in uninfected and HSV-1-infected corneas. Immunofluorescence staining for CXCR4 and CXCL12 protein was performed in the frozen sections of herpes stromal keratitis (HSK) corneas. Flow cytometry assay characterized the CXCR4-expressing cells in uninfected and HSV-1-infected corneas.

RESULTS

Flow cytometry data showed CXCR4 expressing cells in the separated epithelium and stroma of uninfected corneas. In the uninfected stroma, CD11b + F4/80+ macrophages are the predominant CXCR4-expressing cells. In contrast, most CXCR4 expressing cells in the uninfected epithelium were CD207 (langerin)+, CD11c+, and expressed MHC class II molecule, documenting the Langerhans cells (LCs) phenotype. After corneal HSV-1 infection, CXCR4 and CXCL12 mRNA levels increased significantly in HSK corneas than in uninfected corneas. Immunofluorescence staining showed CXCR4 and CXCL12 protein localization in the newly formed blood vessels in the HSK cornea. Furthermore, the infection resulted in LCs proliferation, causing an increase in their numbers in the epithelium at 4 days post-infection (p.i.). However, by 9-day p.i., the LCs numbers declined to the counts observed in naïve corneal epithelium. Our results also showed neutrophils and vascular endothelial cells as the prominent CXCR4-expressing cell types in the stroma of HSK corneas.

CONCLUSIONS

Together, our data demonstrate the expression of CXCR4 on resident antigen presenting cells in the uninfected cornea and on infiltrating neutrophils and newly formed blood vessels in the HSK cornea.

Systemic inflammatory regulators and proliferative diabetic retinopathy: A bidirectional Mendelian randomization study

Background

Increasing evidence shows that systemic inflammation is an embedded mechanism of proliferative diabetic retinopathy (PDR). However, the specific systemic inflammatory factors involved in this process remained obscure. The study aimed to identify the upstream and downstream systemic regulators of PDR by using Mendelian randomization (MR) analyses.

Methods

We performed a bidirectional two-sample MR analysis implementing the results from genome-wide association studies for 41 serum cytokines from 8,293 Finnish individuals, and PDR from FinnGen consortium (2,025 cases vs. 284,826 controls) and eight cohorts of European ancestry (398 cases vs. 2,848 controls), respectively. The inverse-variance-weighted method was adopted as the main MR method, and four additional MR methods (MR-Egger, weighted-median, MR-pleiotropy residual sum and outlier (MR-PRESSO), and MR-Steiger filtering methods) were used for the sensitivity analyses. Results from FinnGen and eight cohorts were pooled into a meta-analysis.

Results

Our results showed that genetically predicted higher stem cell growth factor-β (SCGFb) and interleukin-8 were positively associated with an elevated risk of PDR, with a combined effect of one standard deviation (SD) increase in SCGFb and interleukin-8 causing 11.8% [95% confidence interval (CI): 0.6%, 24.2%]) and 21.4% [95% CI: 3.8%, 41.9%]) higher risk of PDR, respectively. In contrast, genetically predisposition to PDR showed a positive association with the increased levels of growth-regulated oncogene-α (GROa), stromal cell-derived factor-1 alpha (SDF1a), monocyte chemotactic protein-3 (MCP3), granulocyte colony-stimulating factor (GCSF), interleukin-12p70, and interleukin-2 receptor subunit alpha (IL-2ra).

Conclusions

Our MR study identified two upstream regulators and six downstream effectors of PDR, providing opportunities for new therapeutic exploitation of PDR onset. Nonetheless, these nominal associations of systemic inflammatory regulators and PDR require validation in larger cohorts.

Diabetic Retinopathy: Soluble and Imaging Ocular Biomarkers

Diabetic retinopathy (DR), the most common microvascular complication of diabetes mellitus, represents the leading cause of acquired blindness in the working-age population. Due to the potential absence of symptoms in the early stages of the disease, the identification of clinical biomarkers can have a crucial role in the early diagnosis of DR as well as for the detection of prognostic factors. In particular, imaging techniques are fundamental tools for screening, diagnosis, classification, monitoring, treatment planning and prognostic assessment in DR. In this context, the identification of ocular and systemic biomarkers is crucial to facilitate the risk stratification of diabetic patients; moreover, reliable biomarkers could provide prognostic information on disease progression as well as assist in predicting a patient's response to therapy. In this context, this review aimed to provide an updated and comprehensive overview of the soluble and anatomical biomarkers associated with DR.

Targeting Redundant ROBO1 and SDF-1 Pathways Prevents Adult Hemangioblast Derived-EPC and CEC Activity Effectively Blocking Tumor Neovascularization

Neovascularization is a key therapeutic target for cancer treatment. However, anti-angiogenic therapies have shown modest success, as tumors develop rapid resistance to treatment owing to activation of redundant pathways that aid vascularization. We hypothesized that simultaneously targeting different pathways of neovascularization will circumvent the current issue of drug resistance and offer enhanced therapeutic benefits. To test this hypothesis, we made use of two distinct models of tumor-neovascularization, which exhibit equally dense microvasculature but show disparate sensitivity to anti-SDF-1 treatment. Lewis lung carcinoma (LLC) is primarily a vasculogenic-tumor that is associated with HSC functioning as a hemangioblast to generate circulating Endothelial Progenitor Cells contributing to formation of new blood vessels, and responds to anti-SDF-1 treatment. B16F0 melanoma is an angiogenic-tumor that derives new blood vessels from existing vasculature and is resistant to anti-SDF-1 therapy. In this study, we observed increased expression of the angiogenic-factor, Robo1 predominantly expressed on the blood vessels of B16F0 tumor. Blockade of Robo1 by the decoy receptor, RoboN, resulted in reduced microvascular-density and tumor-growth. However, this was associated with mobilization of BM-cells into the B16F0 tumor, thus switching the mode of neovascularization from angiogenic to vasculogenic. The use of a combinatorial treatment of RoboN and the monoclonal anti-SDF-1 antibody effectively attenuated tumor-growth and inhibited both angiogenic and BM-derived microvessels.

The role of inflammation in immune system of diabetic retinopathy: Molecular mechanisms, pathogenetic role and therapeutic implications

Diabetic retinopathy is one of the most common complications of diabetes mellitus and the leading cause of low vision and blindness worldwide. Mounting evidence demonstrates that inflammation is a key mechanism driving diabetes-associated retinal disturbance, yet the pathophysiological process and molecular mechanisms of inflammation underlying diabetic retinopathy are not fully understood. Cytokines, chemokines, and adhesion molecules interact with each other to form a complex molecular network that propagates the inflammatory and pathological cascade of diabetic retinopathy. Therefore, it is important to understand and elucidate inflammation-related mechanisms behind diabetic retinopathy progression. Here, we review the current understanding of the pathology and pathogenesis of inflammation in diabetic retinopathy. In addition, we also summarize the relevant clinical trials to further suggest inflammation-targeted therapeutics for prevention and management of diabetic retinopathy.

SDF‑1α/CXCR4 signaling promotes capillary tube formation of human retinal vascular endothelial cells by activating ERK1/2 and PI3K pathways in vitro

The purpose of this study is to address the effect and mechanism of stromal cell‑derived factor‑1 (SDF‑1)α/chemokine (C‑X‑C motif) receptor 4 (CXCR4) signaling on capillary tube formation of human retinal vascular endothelial cells (HRECs). The expression of CXCR4 in HRECs was quantified by reverse transcription (RT‑PCR) and western blotting. The effects of SDF‑1α/CXCR4 signaling in capillary tube formation and migration of HRECs was examined using three‑dimensional Matrigel assay and wound scratching assay respectively in vitro. Cell proliferation of HRECs was examined using cell counting kit (CCK)‑8 assay in the presence of different concentrations of SDF‑1α protein. The effect of SDF‑1α/CXCR4 signaling in HREC expression of VEGF, basic fibroblast growth factor (bFGF), IL‑8 and intercellular cell adhesion molecule (ICAM)‑1 was examined using RT‑PCR and western blotting. RT‑PCR and western blot analysis revealed CXCR4 was expressed in HRECs. The number of intact capillary tubes formed by HRECs in the presence of SDF‑1α was markedly more compared with a PBS treated control group. However, it was reduced with treatment with an CXCR4 antagonist. Wound scratching assay showed a significant increase in the number of migrated HRECs under SDF‑1α stimulation and the number was reduced with treatment with an CXCR4 antagonist. RT‑PCR and western blotting showed that SDF‑1α significantly promoted VEGF, bFGF, IL‑8 and ICAM‑1 expression in HRECs. The proliferation of HRECs in the presence of SDF‑1α was promoted in a dosage‑dependent manner. SDF‑1α/CXCR4 signaling can increase HREC capillary tube formation through promoting HREC migration, proliferation and expression of VEGF, bFGF, IL‑8 and ICAM‑1.

CXCR4/CXCL12 Activities in the Tumor Microenvironment and Implications for Tumor Immunotherapy

Simple Summary

Chemokines are small soluble proteins that control and regulate cell trafficking within and between tissues by binding to their receptors. Among them, CXCL12 and its receptor CXCR4 appeared with ancestral vertebrates, are expressed almost ubiquitously, and play essential roles in embryogenesis and organogenesis. In addition, CXCL12 and CXCR4 are involved in antigen recognition by T and B cells and in shaping the tumor microenvironment (TME), mainly towards dampening immune responses. New data indicate that CXCR4 interacts with the surface protein CD47 in a novel form of immunosurveillance, called ImmunoGenic Surrender (IGS). Following the co-internalization of CXCR4 and CD47 in tumor cells, macrophages phagocytose them and cross-present their antigens to the adaptive immune system, leading to tumor rejection in a fraction of mice. All of these specific activities of CXCL12 and CXCR4 in antigen presentation might be complementary to current immunotherapies.

Abstract

CXCR4 is a G-Protein coupled receptor that is expressed nearly ubiquitously and is known to control cell migration via its interaction with CXCL12, the most ancient chemokine. The functions of CXCR4/CXCL12 extend beyond cell migration and involve the recognition and disposal of unhealthy or tumor cells. The CXCR4/CXCL12 axis plays a relevant role in shaping the tumor microenvironment (TME), mainly towards dampening immune responses. Notably, CXCR4/CXCL12 cross-signal via the T and B cell receptors (TCR and BCR) and co-internalize with CD47, promoting tumor cell phagocytosis by macrophages in an anti-tumor immune process called ImmunoGenic Surrender (IGS). These specific activities in shaping the immune response might be exploited to improve current immunotherapies.

Deep Red Lesion Classification for Early Screening of Diabetic Retinopathy

Diabetic retinopathy (DR) is an asymptotic and vision-threatening complication among working-age adults. To prevent blindness, a deep convolutional neural network (CNN) based diagnosis can help to classify less-discriminative and small-sized red lesions in early screening of DR patients. However, training deep models with minimal data is a challenging task. Fine-tuning through transfer learning is a useful alternative, but performance degradation, overfitting, and domain adaptation issues further demand architectural amendments to effectively train deep models. Various pre-trained CNNs are fine-tuned on an augmented set of image patches. The best-performing ResNet50 model is modified by introducing reinforced skip connections, a global max-pooling layer, and the sum-of-squared-error loss function. The performance of the modified model (DR-ResNet50) on five public datasets is found to be better than state-of-the-art methods in terms of well-known metrics. The highest scores (0.9851, 0.991, 0.991, 0.991, 0.991, 0.9939, 0.0029, 0.9879, and 0.9879) for sensitivity, specificity, AUC, accuracy, precision, F1-score, false-positive rate, Matthews’s correlation coefficient, and kappa coefficient are obtained within a 95% confidence interval for unseen test instances from e-Ophtha_MA. This high sensitivity and low false-positive rate demonstrate the worth of a proposed framework. It is suitable for early screening due to its performance, simplicity, and robustness.

The misunderstood link between SARS-CoV-2 and angiogenesis. A narrative review

Novel Coronavirus Disease 2019 (Covid-19) is associated with multi-systemic derangement, including circulatory dysfunction with features of endothelial dysfunction, microangiopathic thrombosis and angiocentric inflammation. Recently, intussusceptive angiogenesis has been implicated in the pathogenesis of the disease. Herein, we conducted a narrative review according to the SANRA guidelines to review and discuss data regarding splitting angiogenesis including mechanisms, drivers, regulators and putative roles. Relevant angiogenic features in Covid-19, including their potential role in inflammation, endothelial dysfunction and permeability, as well as their use as prognostic markers and therapeutic roles are reviewed. Splitting angiogenesis in Covid-19 involve hypoxia, hypoxia-inducible factors, classic angiogenic mediators, such as the Vascular Endothelial Growth Factor (VEGF), Angiopoietins, hyperinflammation and cytokine storm, and dysregulation of the Renin-Angiotensin-Aldosterone System, which combined, interact to promote intussusception. Data regarding the use of angiogenic mediators as prognostic tools is summarized and suggest that angiopoietins and VEGF are elevated in Covid-19 patients and predictors of adverse outcomes. Finally, we reviewed the scarce data regarding angiogenic mediators as therapeutic targets. These preliminary findings suggest a potential benefit of bevacizumab as an add-on therapy.

TLR2 signaling contributes to the angiogenesis of oxygen-induced retinopathy

PURPOSE

To evaluate the role of Toll-like receptor 2 (TLR2) signaling in retinal neovascularization in a mouse model of oxygen-induced retinopathy (OIR).

MATERIALS AND METHODS

The OIR model was established in C57BL/6J wild type (WT) mice and TLR2^-/- mice. Retinal neovascularization in the OIR model was measured by counting new vascular cell nuclei above the internal limiting membrane and analyzing flat-mounted retinas perfused with fluorescein dextran and immunostained with Griffonia Simplicifolia (GS) isolectin. The expression of TLR2 and VEGF in the retina was detected by immunofluorescence. Expression of TGF- β1, b-FGF, and IL-6 mRNA in the retina was measured by quantitative real-time PCR.

RESULTS

Compared to WT OIR mice, retinal neovascularization was attenuated in TLR2^-/- OIR mice. The co-expressions of TLR2 and VEGF were remarkably and consistently increased in WT OIR mice; however, there was no expression of TLR2 and a significant decrease in VEGF expression in TLR2^-/- OIR mice. These results suggest that TLR2 plays a central role in OIR model angiogenesis. Expression of TGF- β1, b-FGF, and IL-6 mRNA were reduced in the TLR2^-/- OIR mice, suggesting that the inflammatory response induced by TLR2 relates to angiogenesis.

CONCLUSION

TLR2 signaling in the retina is associated with neovascularization in mice. Inflammation contributes to the activation of angiogenesis and is partially mediated through the TLR2-VEGF retinal signaling pathway.

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.

[Effects of Fibrates on Risk of Development of Diabetic Retinopathy in Japanese Working Age Patients with Type 2 Diabetes and Dyslipidemia: a Retrospective Cohort Study]

The aims of the present study were to investigate the effects of fenofibrate and bezafibrate on the risk of development of diabetic retinopathy (DR) in patients with type 2 diabetes and dyslipidemia. Japanese working age patients with type 2 diabetes and dyslipidemia were extracted from the Nihon University School of Medicine Clinical Data Warehouse. These patients were divided into three groups: control group (n=2549), fenofibrate group (n=40), and bezafibrate group (n=135). Multivariate logistic regression analysis was performed to assess the association between fibrates and the development of DR. After adjustment for covariates, fenofibrate showed no association with the risk of DR [adjusted odds ratio (OR), 0.160; 95% CI, 0.021-1.209; p=0.0758]. Bezafibrate also showed no association with the risk of DR (adjusted OR, 0.731; 95% CI, 0.411-1.299; p=0.2855). However, poor control of hemoglobin A1c (HbA1c ≥8.0%; adjusted OR, 3.623; 95% CI, 2.649-4.956; p<0.0001) and high low-density lipoprotein cholesterol (LDL-C ≥140 mg/dL; adjusted OR, 1.399; 95% CI, 1.013-1.932; p=0.0415) within the follow-up period of type 2 diabetes and dyslipidemia increased the risk of DR. Our results suggested that to prevent development of DR in patients with type 2 diabetes and dyslipidemia, controlling LDL-C levels as well as HbA1c levels under coexistence type 2 diabetes and dyslipidemia is more important than the selection of fibrate.

At the Bench: Pre-clinical evidence for multiple functions of CXCR4 in cancer

Signaling through chemokine receptor, C-X-C chemokine receptor type 4 (CXCR4) regulates essential processes in normal physiology, including embryogenesis, tissue repair, angiogenesis, and trafficking of immune cells. Tumors co-opt many of these fundamental processes to directly stimulate proliferation, invasion, and metastasis of cancer cells. CXCR4 signaling contributes to critical functions of stromal cells in cancer, including angiogenesis and multiple cell types in the tumor immune environment. Studies in animal models of several different types of cancers consistently demonstrate essential functions of CXCR4 in tumor initiation, local invasion, and metastasis to lymph nodes and distant organs. Data from animal models support clinical observations showing that integrated effects of CXCR4 on cancer and stromal cells correlate with metastasis and overall poor prognosis in >20 different human malignancies. Small molecules, Abs, and peptidic agents have shown anticancer efficacy in animal models, sparking ongoing efforts at clinical translation for cancer therapy. Investigators also are developing companion CXCR4-targeted imaging agents with potential to stratify patients for CXCR4-targeted therapy and monitor treatment efficacy. Here, pre-clinical studies demonstrating functions of CXCR4 in cancer are reviewed.

Impact of Systemic Dipeptidyl Peptidase-4 Inhibitor Use in Diabetic Macular Edema

BACKGROUND AND OBJECTIVE

To evaluate impact of baseline systemic dipeptidyl peptidase-4 (DPP-4) inhibitor use in diabetic macular edema (DME).

PATIENTS AND METHODS

This was a post hoc exploratory analysis of previously completed randomized, controlled clinical trials (VISTA and VIVID) in patients with DME evaluating intravitreal aflibercept injection (IAI) every 4 weeks (2q4) or every 8 weeks (2q8) or macular laser photocoagulation.

RESULTS

Overall, a small number of patients (12.2% [n = 35], 9.7% [n = 28], and 15.4% [n = 44]) in the laser control, 2q4, and 2q8 groups reported baseline DPP-4 inhibitor use. There were no differences in changes from baseline in best-corrected visual acuity, central subfield thickness, or rates of 2-or-greater-step improvement in Diabetic Retinopathy Severity Scale score based on DPP-4 inhibitor use within each treatment group.

CONCLUSION

DPP-4 inhibitor use at baseline did not influence the magnitude of visual and anatomic benefit in patients with DME being treated with IAI or laser. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:226-234.].

Therapeutic potential of curcumin in diabetic retinopathy (Review)

Diabetic retinopathy (DR) is a type of retinal microangiopathy caused by diabetes mellitus. It has become the leading cause of blindness among working individuals worldwide. DR is becoming increasingly common among younger diabetic patients and there is a need for lifelong treatment. The pathogenic mechanisms of DR are influenced by a number of factors, such as hyperglycemia, hyperlipidemia, inflammatory response and oxidative stress, among others. Currently, the treatment methods for DR mainly include retinal photocoagulation, vitrectomy, or anti‑vascular endothelial growth factor (VEGF) therapy. However, these methods have some disadvantages and limitations. Therefore, it is a matter of great interest and urgency to discover drugs that can target the pathogenesis of DR. Since ancient times, traditional Chinese medicine practitioners have accumulated extensive experiences in the use of Chinese herbal medicine for the prevention and treatment of diseases. In the theory of traditional Chinese medicine, curcumin has the effects of promoting blood circulation and relieving pain. A number of studies have also demonstrated that curcumin has multiple biological activities, including exerting anti‑apoptotic, anti‑inflammatory, antioxidant and antitumor properties. In recent years, studies have also confirmed that curcumin can prevent a variety of diabetic complications, including diabetic nephropathy (DN). However, the preventive and curative effects of curcumin on DR and its mechanisms of action have not yet been fully elucidated. The present review aimed to explore the therapeutic potential of curcumin in diabetes mellitus and DR.

CXCL12 Signaling in the Tumor Microenvironment

Tumor microenvironment (TME) is the local environment of tumor, composed of tumor cells and blood vessels, extracellular matrix (ECM), immune cells, and metabolic and signaling molecules. Chemokines and their receptors play a fundamental role in the crosstalk between tumor cells and TME, regulating tumor-related angiogenesis, specific leukocyte infiltration, and activation of the immune response and directly influencing tumor cell growth, invasion, and cancer progression. The chemokine CXCL12 is a homeostatic chemokine that regulates physiological and pathological process such as inflammation, cell proliferation, and specific migration. CXCL12 activates CXCR4 and CXCR7 chemokine receptors, and the entire axis has been shown to be dysregulated in more than 20 different tumors. CXCL12 binding to CXCR4 triggers multiple signal transduction pathways that regulate intracellular calcium flux, chemotaxis, transcription, and cell survival. CXCR7 binds with high-affinity CXCL12 and with lower-affinity CXCL11, which binds also CXCR3. Although CXCR7 acts as a CXCL12 scavenger through ligand internalization and degradation, it transduces the signal mainly through β-arrestin with a pivotal role in endothelial and neural cells. Recent studies demonstrate that TME rich in CXCL12 leads to resistance to immune checkpoint inhibitors (ICI) therapy and that CXCL12 axis inhibitors sensitize resistant tumors to ICI effect. Thus targeting the CXCL12-mediated axis may control tumor and tumor microenvironment exerting an antitumor dual action. Herein CXCL12 physiology, role in cancer biology and in composite TME, prognostic role, and the relative inhibitors are addressed.

Association of serum CXCL12 levels with arthropathy in patients with systemic sclerosis

AIM

Systemic sclerosis (SSc) is an autoimmune connective tissue disease, in which extensive fibrotic change and vasculopathy affect the skin and various internal organs. It also involves the joints, causing stiffness, arthralgia, and arthritis. Although arthropathy is commonly observed in SSc, its underlying mechanism remains unknown. CXCL12, also known as stromal cell derived factor 1, is associated with inflammation, mesenchymal cell recruitment, angiogenesis, and collagen production, and is implicated in the development of various joint diseases. To assess the potential contribution of CXCL12 to SSc development, we investigated the clinical association of serum CXCL12 levels in patients with SSc.

METHOD

We conducted a cross-sectional analysis of 68 patients with SSc and 20 healthy controls recruited in a single center over 9 years. Serum CXCL12 levels were measured by enzyme-linked immunosorbent assay.

RESULTS

Serum CXCL12 levels were significantly higher in patients with SSc than in healthy controls (median 1554.0 pg/mL, 25th-75th centiles 1313.0-1914.0 pg/mL vs 967.4 pg/mL, 608.8-1271.0 pg/mL, P < 0.001). Patients with SSc with elevated CXCL12 levels had significantly more cases of arthropathy than those with normal CXCL12 levels (85.7% vs 25.0%, P = 0.01). Furthermore, patients with SSc with elevated CXCL12 levels showed an increased trend in the prevalence of limited range of motion of the finger joints compared with those with normal CXCL12 levels (60.0% vs 18.6%, P =0 .07). Moreover, serum CXCL12 levels were significantly correlated with the titers of rheumatoid factor in patients with SSc (r = .41, P = 0.001).

CONCLUSION

Elevated serum CXCL12 levels may be related to the development of SSc arthropathy.

Toward the Clinical Application of Therapeutic Angiogenesis Against Pediatric Ischemic Retinopathy

Therapeutic angiogenesis refers to strategies of inducing angiogenesis to treat diseases involving ischemic conditions. Historically, most attempts and achievements have been related to coronary and peripheral artery diseases. In this review, we propose the clinical application of therapeutic angiogenesis for the treatment of pediatric ischemic retinopathy, including retinopathy of prematurity, familial exudative retinopathy, and NDP-related retinopathy. These diseases are all characterized by the reduction of physiological angiogenesis and the following induction of pathological angiogenesis. Therapeutic angiogenesis, which supplements insufficient physiological angiogenesis, may be a therapeutic approach for ischemic conditions. Various molecules and modalities can be utilized to apply therapeutic angiogenesis for the treatment of ischemic retinopathy, as in coronary and peripheral artery diseases. Experiences with cardiovascular diseases provide a useful reference for the further clinical application of therapeutic angiogenesis in pediatric ischemic retinopathy. Recombinant proteins and gene therapy are powerful tools to deliver angiogenic factors to retinal tissues directly. Furthermore, endothelial progenitor or bone marrow-derived cells can be injected into the vitreous cavity of the eye for therapeutic angiogenesis. Intraocular injections are highly promising for the delivery of therapeutics for therapeutic angiogenesis. We expect that therapeutic angiogenesis will be a breakthrough in the treatment of pediatric ischemic retinopathy.

A potential novel therapeutic target in diabetic retinopathy: a chemokine receptor (CCR2/CCR5) inhibitor reduces retinal vascular leakage in an animal model

PURPOSE

We have previously shown that the chemokine CCL2 plays an important role in monocyte trafficking into the retina and alteration of the BRB in an animal model of diabetic retinopathy. In this study, we examined the effect of pharmacologically targeting the chemokine pathway to reduce the increased retinal vascular permeability in this model.

METHODS

C57BL/6 J mice were made diabetic using streptozotocin. After 4 months of diabetes, mice (n = 10) were treated by intraperitoneal injections of TAK-779 (dual CCR2/CCR5 inhibitor) (30 mg/kg) daily for 2 weeks. Retinal vascular permeability and protein expression were done using western blot. The SDF-1 levels were measured by ELISA. Immune cell infiltration in the retinas was measured using flow cytometry.

RESULTS

The dual inhibitor significantly decreased retinal vascular permeability in diabetic animals. There was a significant reduction in macrophage/microglia infiltration in the retinas of treated animals. Levels of SDF-1 and ICAM-1 were significantly reduced and the tight junction protein ZO-1 level was increased, and phospho-VE-Cad was significantly reduced with drug treatment.

CONCLUSIONS

A chemokine receptor inhibitor (CCR2/CCR5) can reduce retinal vascular permeability in diabetic animals. Targeting the chemokine pathway pharmacologically may be used as a novel therapeutic strategy in management of diabetic macular edema.

Effects and Mechanism of Action of PX-478 in Oxygen-Induced Retinopathy in Mice

IMPORTANCE

Retinopathy of prematurity (ROP) is an important risk factor for blindness in children due to neovascularization (NV). Hypoxia stimulates the formation of NV, as retinal hypoxia affects the stability and function of hypoxia-inducible factor (HIF) transcription factors. The purpose of this study is to study the mechanism of ROP and provide theoretical basis for clinical treatment of ROP.

OBJECTIVE

In the present study, we used a mouse model of oxygen-induced retinopathy (OIR) to demonstrate the effects of the HIF-1α inhibitor PX-478 on OIR, and to determine its mechanism of action, to provide a theoretical basis for the clinical treatment of ROP.

MATERIALS AND METHODS

The OIR mouse model was induced by exposing neonatal mouse pups and their mothers to 75 ± 5% oxygen from postnatal day 7 (P7) to P12, before being returned to room air from P12 to P17. Flat mount analyses were performed at P12 and P17. Hif1a, Hif2a, Hif3a, and Vegfa mRNA were detected by reverse transcription-polymerase chain reaction in OIR mice at P12 and P17. Hif1a and Vegfa mRNA were detected in OIR mice at P12 and P17 treatment with PX-478. Western blot analyses were used to assess the levels of HIF-1α, VEGF-A, and EPO before and after treatment with PX-478 at P12 and P17.

RESULTS

Hif1a mRNA was increased in OIR mice at P12 and P17, while Vegfa mRNA was increased at P12 and P17. HIF-1α, VEGF-A, and EPO protein levels were increased in OIR mice at P12 and P17, as compared to control mice at the same age (all p < 0.05). Inhibition of HIF-1α by injection of PX-478 in OIR mice (P9-P16) caused a decrease in the retinal avascular area at P12 and P17 (both p < 0.05), NV areas at P17 (p < 0.05), Vegfa mRNA decreased at P12 and P17, as compared to control mice (p < 0.05), and VEGF-A and EPO protein levels at P12 and P17, as compared to control mice. Our study found that there were PX-478 both retina and vitreous body of OIR. Inhibition of HIF-1α by injection of PX-478 in OIR mice caused a decrease in the retinal avascular area at P12 and P17, NV areas decreased at P17, VEGF-A and EPO protein levels at P12 and P17. Endothelial cell migration assays and cell tube formation indication PX-478 attenuate cell migration and significantly weakened the cell cavity formation under the condition of hypoxia.

CONCLUSION

HIF-1α plays a main role in OIR and can be considered a therapeutic target in OIR by suppressing downstream angiogenic factors, PX-478 decreasing the retinal avascular area and NV.

Muscle-derived SDF-1α/CXCL12 modulates endothelial cell proliferation but not exercise training-induced angiogenesis

Chemokines are critical mediators of angiogenesis in several physiological and pathological conditions; however, a potential role for muscle-derived chemokines in exercise-stimulated angiogenesis in skeletal muscle remains poorly understood. Here, we postulated that the chemokine stromal cell-derived factor-1 (SDF-1α/C-X-C motif chemokine ligand 12: CXCL12), shown to promote neovascularization in several organs, contributes to angiogenesis in skeletal muscle. We found that CXCL12 is abundantly expressed in capillary-rich oxidative soleus and exercise-trained plantaris muscles. CXCL12 mRNA and protein were also abundantly expressed in muscle-specific peroxisome proliferator-activated receptor γ coactivator 1α transgenic mice, which have a high proportion of oxidative muscle fibers and capillaries when compared with wild-type littermates. We then generated CXCL12 muscle-specific knockout mice but observed normal baseline capillary density and normal angiogenesis in these mice when they were exercise trained. To get further insight into a potential CXCL12 role in a myofiber-endothelial cell crosstalk, we first mechanically stretched C2C12 myotubes, a model known to induce stretch-related chemokine release, and observed increased CXCL12 mRNA and protein. Human umbilical vein endothelial cells (HUVECs) exposed to conditioned medium from cyclically stretched C2C12 myotubes displayed increased proliferation, which was dependent on CXCL12-mediated signaling through the CXCR4 receptor. However, HUVEC migration and tube formation were unaltered under these conditions. Collectively, our findings indicate that increased muscle contractile activity enhances CXCL12 production and release from muscle, potentially contributing to endothelial cell proliferation. However, redundant signals from other angiogenic factors are likely sufficient to sustain normal endothelial cell migration and tube formation activity, thereby preserving baseline capillary density and exercise training-mediated angiogenesis in muscles lacking CXCL12.

CXCL12/CXCR4 signal transduction in diseases and its molecular approaches in targeted-therapy

Chemokines are small molecules called "chemotactic cytokines" and regulate many processes like leukocyte trafficking, homing of immune cells, maturation, cytoskeletal rearrangement, physiology, migration during development, and host immune responses. These proteins bind to their corresponding 7-membrane G-protein-coupled receptors. Chemokines and their receptors are anti-inflammatory factors in autoimmune conditions, so consider as potential targets for neutralization in such diseases. They also express by cancer cells and function as angiogenic factors, and/or survival/growth factors that enhance tumor angiogenesis and development. Among chemokines, the CXCL12/CXCR4 axis has significantly been studied in numerous cancers and autoimmune diseases. CXCL12 is a homeostatic chemokine, which is acts as an anti-inflammatory chemokine during autoimmune inflammatory responses. In cancer cells, CXCL12 acts as an angiogenic, proliferative agent and regulates tumor cell apoptosis as well. CXCR4 has a role in leukocyte chemotaxis in inflammatory situations in numerous autoimmune diseases, as well as the high levels of CXCR4, observed in different types of human cancers. These findings suggest CXCL12/CXCR4 as a potential therapeutic target for therapy of autoimmune diseases and open a new approach to targeted-therapy of cancers by neutralizing CXCL12 and CXCR4. In this paper, we reviewed the current understanding of the role of the CXCL12/CXCR4 axis in disease pathology and cancer biology, and discuss its therapeutic implications in cancer and diseases.

SDF-1/CXCR4 signalling is involved in blood vessel growth and remodelling by intussusception

The precise mechanisms of SDF‐1 (CXCL12) in angiogenesis are not fully elucidated. Recently, we showed that Notch inhibition induces extensive intussusceptive angiogenesis by recruitment of mononuclear cells and it was associated with increased levels of SDF‐1 and CXCR4. In the current study, we demonstrated SDF‐1 expression in liver sinusoidal vessels of Notch1 knockout mice with regenerative hyperplasia by means of intussusception, but we did not detect any SDF‐1 expression in wild‐type mice with normal liver vessel structure. In addition, pharmacological inhibition of SDF‐1/CXCR4 signalling by AMD3100 perturbs intussusceptive vascular growth and abolishes mononuclear cell recruitment in the chicken area vasculosa. In contrast, treatment with recombinant SDF‐1 protein increased microvascular density by 34% through augmentation of pillar number compared to controls. The number of extravasating mononuclear cells was four times higher after SDF‐1 application and two times less after blocking this pathway. Bone marrow‐derived mononuclear cells (BMDC) were recruited to vessels in response to elevated expression of SDF‐1 in endothelial cells. They participated in formation and stabilization of pillars. The current study is the first report to implicate SDF‐1/CXCR4 signalling in intussusceptive angiogenesis and further highlights the stabilizing role of BMDC in the formation of pillars during vascular remodelling.

Human vitreous in proliferative diabetic retinopathy: Characterization and translational implications

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

Involvement of premacular mast cells in the pathogenesis of macular diseases

We previously reported on the elevated intravitreal activities of tryptase and chymase in association with idiopathic epiretinal membrane (ERM) and idiopathic macular hole (MH). In this present study, we investigated the potential intraocular production of these serine proteases, and measured and compared tryptase and chymase activities in the vitreous body and serum in ERM, MH, proliferative diabetic retinopathy (PDR), and rhegmatogenous retinal detachment (RRD) patients. In addition, nuclear staining with hematoxylin and eosin (H&E) and mast-cell staining with toluidine blue were performed on samples of the vitreous core and bursa premacularis (BPM) of MH. We also performed immunostaining on the above two regions of vitreous samples for MH with anti-tryptase antibody, anti-chymase antibody, anti-podoplanin antibody, anti-lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) antibody, and anti-fibroblast antibody. Moreover, we performed immunostaining with anti-tryptase antibody and anti-chymase antibody on ERMs collected intraoperatively. Tryptase activity in the vitreous body was significantly higher in ERM and MH than in PDR. However, no significant differences were observed in the tryptase activity in the serum among these four diseases. Chymase activity in the vitreous body was significantly higher in MH than in the other three diseases, yet chymase activity in the serum was below detection limit in any of the diseases. Nuclear staining with H&E revealed an abundance of nuclei in the BPM region, but few in the surrounding area. Mast-cell staining with toluidine blue revealed that the BPM showed metachromatic staining. In immunostaining with anti-fibroblasts antibody, anti-tryptase antibody, anti-chymase antibody, anti-podoplanin antibody, and anti-LYVE-1 antibody, the BPM stained more strongly than the vitreous core. Tryptase and chymase-positive cells were also observed in ERM. These findings revealed that the presence of mast cells in the BPM potentially represent the source of these serine proteases. Moreover, the BPM, as a lymphatic tissue, may play an important role in the pathogenesis of macular disease.

Novel stem cell and gene therapy in diabetic retinopathy, age related macular degeneration, and retinitis pigmentosa

Degenerative retinal disease leads to significant visual morbidity worldwide. Diabetic retinopathy and macular degeneration are leading causes of blindness in the developed world. While current therapies for these diseases slow disease progression, stem cell and gene therapy may also reverse the effects of these, and other, degenerative retinal conditions. Novel therapies being investigated include the use of various types of stem cells in the regeneration of atrophic or damaged retinal tissue, the prolonged administration of neurotrophic factors and/or drug delivery, immunomodulation, as well as the replacement of mutant genes, and immunomodulation through viral vector delivery. This review will update the reader on aspects of stem cell and gene therapy in diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa and other less common inherited retinal dystrophies. These therapies include the use of adeno-associated viral vector-based therapies for treatment of various types of retinitis pigmentosa and dry age-related macular degeneration. Other potential therapies reviewed include the use of mesenchymal stem cells in local immunomodulation, and the use of stem cells in generating structures like three-dimensional retinal sheets for transplantation into degenerative retinas. Finally, aspects of stem cell and gene therapy in diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, and other less common inherited retinal dystrophies will be reviewed.

The Role of the CXCL12/CXCR4/ACKR3 Axis in Autoimmune Diseases

Chemokine receptors are members of the G protein-coupled receptor superfamily. These receptors are intimately involved in cell movement, and thus play a critical role in several physiological and pathological situations that require the precise regulation of cell positioning. CXCR4 is one of the most studied chemokine receptors and is involved in many functions beyond leukocyte recruitment. During embryogenesis, it plays essential roles in vascular development, hematopoiesis, cardiogenesis, and nervous system organization. It has been also implicated in tumor progression and autoimmune diseases and, together with CD4, is one of the co-receptors used by the HIV-1 virus to infect immune cells. In contrast to other chemokine receptors that are characterized by ligand promiscuity, CXCR4 has a unique ligand-stromal cell-derived factor-1 (SDF1, CXCL12). However, this ligand also binds ACKR3, an atypical chemokine receptor that modulates CXCR4 functions and is overexpressed in multiple cancer types. The CXCL12/CXCR4/ACKR3 axis constitutes a potential therapeutic target for a wide variety of inflammatory diseases, not only by interfering with cell migration but also by modulating immune responses. Thus far, only one antagonist directed against the ligand-binding site of CXCR4, AMD3100, has demonstrated clinical relevance. Here, we review the role of this ligand and its receptors in different autoimmune diseases.

Anti-angiogenic effects of the DPP-4 inhibitor linagliptin via inhibition of VEGFR signalling in the mouse model of oxygen-induced retinopathy

AIMS/HYPOTHESIS

Linagliptin has protective effects on the retinal neurovascular unit but, in proliferative retinopathy, dipeptidyl peptidase 4 (DPP-4) inhibition could be detrimental. The aim of this study was to assess the effect of linagliptin on ischaemia-induced neovascularisation of the retina.

METHODS

C57BL/6J and glucagon-like peptide 1 (GLP-1) receptor (Glp1r)^-/- mice were subjected to a model of oxygen-induced retinopathy (OIR). Both strains were subcutaneously treated with linagliptin from postnatal days 12 to 16. Non-injected OIR and non-exposed mice served as controls. Capillary proliferations and systemic levels of active GLP-1 were quantified. The effects of linagliptin on vascular endothelial growth factor (VEGF)-induced downstream signalling were assessed in human umbilical vein endothelial cells (HUVECs) using western blot for retinal phosphorylated extracellular signal-regulated kinase (ERK)1/2 and retinal gene expression analyses.

RESULTS

Linagliptin treatment led to an increase in active GLP-1 and a decreased number of neovascular nuclei in OIR mice vs controls (-30%, p < 0.05). As the reduction in neovascularisation was similar in both C57BL/6J and Glp1r^-/- mice, the anti-angiogenic effects of linagliptin were independent of GLP-1R status. The expression of Vegf (also known as Vegfa) and Hif1a was increased in C57BL/6J OIR mice upon linagliptin treatment (three- vs 1.5-fold, p < 0.05, p < 0.01, respectively). In HUVECs, linagliptin inhibited VEGF-induced increases in mitogen-activated protein kinase (MAPK)/ERK (-67%, p < 0.001) and MAPK/c-Jun N-terminal kinase (JNK) (-13%, p < 0.05) pathway activities. In the retinas of C57BL/6J mice, p-ERK1/2 levels were significantly reduced upon linagliptin treatment (-47%, p < 0.05).

CONCLUSIONS/INTERPRETATION

Systemic treatment with linagliptin demonstrated GLP-1R-independent anti-angiogenic effects mediated by an inhibition of VEGF receptor downstream signalling. The specific effects of linagliptin on diabetic retinopathy are of potential benefit for individuals with diabetes, independent of metabolic effects.

Pathological roles of the homeostatic chemokine CXCL12

CXCL12 is a CXC chemokine that traditionally has been classified as a homeostatic chemokine. It contributes to physiological processes such as embryogenesis, hematopoiesis and angiogenesis. In contrast to these homeostatic functions, increased expression of CXCL12 in general, or of a specific CXCL12 splicing variant has been demonstrated in various pathologies. In addition to this increased or differential transcription of CXCL12, also upregulation of its receptors CXC chemokine receptor 4 (CXCR4) and atypical chemokine receptor 3 (ACKR3) contributes to the onset or progression of diseases. Moreover, posttranslational modification of CXCL12 during disease progression, through interaction with locally produced molecules or enzymes, also affects CXCL12 activity, adding further complexity. As CXCL12, CXCR4 and ACKR3 are broadly expressed, the number of pathologies wherein CXCL12 is involved is growing. In this review, the role of the CXCL12/CXCR4/ACKR3 axis will be discussed for the most prevalent pathologies. Administration of CXCL12-neutralizing antibodies or small-molecule antagonists of CXCR4 or ACKR3 delays disease onset or prevents disease progression in cancer, viral infections, inflammatory bowel diseases, rheumatoid arthritis and osteoarthritis, asthma and acute lung injury, amyotrophic lateral sclerosis and WHIM syndrome. On the other hand, CXCL12 has protective properties in Alzheimer's disease and multiple sclerosis, has a beneficial role in wound healing and has crucial homeostatic properties in general.

Activation of Toll-like receptor 3 promotes pathological corneal neovascularization by enhancement of SDF-1-mediated endothelial progenitor cell recruitment

Toll-like receptors (TLRs) play an important role in inflammatory and immunological responses, which are intimately related to neovascularization. However, the precise mode of action of TLR3 in neovascularization still remains ambiguous. In this study, we sought to investigate the role of TLR3 in pathological corneal neovascularization (CNV) using a mouse model of alkali-induced CNV. CNV was attenuated in TLR3-deficient mice, and the absence of TLR3 led to decreased production of stromal cell-derived factor 1 (SDF-1), a well-characterized cytokine that regulates the recruitment of endothelial progenitor cells (EPCs) to the sites of neo-angiogenic niches in the injured tissues. Topical administration of polyinosinic-polycytidylic acid [poly (I:C)], a synthetic ligand for TLR3, to the injured cornea promoted CNV in wild type (WT) mice but not in TLR3-deficient mice. In addition, the effect of poly (I:C) on WT mice was abolished by addition of SDF-1 receptor antagonist AMD 3100. Furthermore, poly (I:C) treatment in vitro enhanced the migration of EPCs, whereas the enhanced migration was abolished by AMD 3100. These results indicate an essential role of TLR3 signalling in CNV that involves upregulating SDF-1 production and recruiting EPCs to the sites of injury for neovascularization. Thus, targeting the TLR3 signalling cascade may constitute a novel therapeutic approach for treating neovascularization-related diseases.

Mitochondrial dysfunctions, endothelial progenitor cells and diabetic retinopathy

AIM

Diabetic retinopathy (DR) is the leading cause of vision loss in the working age population. Endothelial progenitor cells (EPC) play a vital role in vascular damage repair. This article will review recent progress regarding mitochondrial and EPC dysfunction associated with DR.

RESULTS

EPCs represent a limited population of adult stem cells possessing vasculogenic potential postnatally; their number and function are changed in DR. Among all the function changes, mitochondrial dysfunction plays an important role in the dysregulation of EPCs, as mitochondria regulate energy balance, and cell fate determination.

CONCLUSIONS

Although the mechanism for the role of mitochondria dysregulation in EPC function remains elusive, mitochondria of EPCs represent a promising target for the treatment of the vasculopathy presented within DR.

Glucocorticoid Impaired the Wound Healing Ability of Endothelial Progenitor Cells by Reducing the Expression of CXCR4 in the PGE2 Pathway

Background: Endothelial progenitor cells (EPCs) can be used to treat ischemic disease in cell-based therapy owing to their neovascularization potential. Glucocorticoids (GCs) have been widely used as strong anti-inflammatory reagents. However, despite their beneficial effects, side effects, such as impairing wound healing are commonly reported with GC-based therapy, and the effects of GC therapy on the wound healing function of EPCs are unclear.

Methods: In this study, we investigated how GC treatment affects the characteristics and wound healing function of EPCs.

Results: We found that GC treatment reduced the proliferative ability of EPCs. In addition, the expression of CXCR4 was dramatically impaired, which suppressed the migration of EPCs. A transplantation study in a flap mouse model revealed that GC-treated EPCs showed a poor homing ability to injured sites and a low activity for recruiting inflammatory cells, which led to wound healing dysfunction. Impairment of prostaglandin E2 (PGE2) synthases, cyclooxygenase (COX2) and microsomal PGE2 synthase 1 (mPEGS1) were identified as being involved in the GC-induced impairment of the CXCR4 expression in EPCs. Treatment with PGE2 rescued the expression of CXCR4 and restored the migration ability of GC-treated EPCs. In addition, the PGE2 signal that activated the PI3K/AKT pathway was identified to be involved in the regulation of CXCR4 in EPCs under the effects of GCs. In addition, similar negative effects of GCs were observed in EPCs under hypoxic conditions. Under hypoxic conditions, GCs independently impaired the PGE2 and HIF2α pathways, which downregulated the expression of CXCR4 in EPCs. Our findings highlighted the influences of GCs on the characteristics and functions of EPCs, suggesting that the use of EPCs for autologous cell transplantation in patients who have used GCs for a long time should be considered carefully.

Generation of an anti-angiogenic endothelial progenitor cell line via endostatin gene transfer

The viability of endothelial progenitor cells (EPCs) as a therapeutic treatment for neovascularization (NV) was subject to investigation in the present study. Furthermore, endostatin has previously been demonstrated to be an inhibitor of angiogenesis and a suppressant of vascular leakage. The aim of the present study was to generate transgenic EPCs with anti-angiogenic effects for the treatment of ocular NV. EPCs were obtained from rat peripheral blood samples and then verified. A lentiviral-endostatin-green fluorescent protein recombinant construct was generated and used to infect EPCs. Transfected cells were then subjected to puromycin selection. Reverse transcription-quantitative polymerase chain reaction and a western blot assay were then applied in order to determine both the endostatin mRNA and protein expression levels, respectively. In addition, vascular endothelial growth factor (VEGF) expression levels were also detected in order to observe the anti-angiogenic effect of the endostatin-transfected EPCs. Following puromycin (1 µg/ml) selection for 4 days, a stable endostatin-transfected EPC line was generated. In this stable endostatin-transfected EPC line, the expression levels of endostatin increased; whereas the expression levels of VEGF decreased. The results of the present study revealed that EPCs can be genetically modified to overexpress endostatin, which may provide the cells with an anti-angiogenic effect via increased expression of endostatin and decreased expression of VEGF. Thus, EPCs genetically modified to overexpress endostatin may serve as a potential therapeutic agent for ocular NV treatment.

Have dipeptidyl peptidase-4 inhibitors ameliorated the vascular complications of type 2 diabetes in large-scale trials? The potential confounding effect of stem-cell chemokines

Drugs that inhibit dipeptidyl peptidase-4 (DPP-4) are conventionally regarded as incretin-based agents that signal through the glucagon-like peptide-1 (GLP-1) receptor. However, inhibition of DPP-4 also potentiates the stem cell chemokine, stromal cell-derived factor-1 (SDF-1), which can promote inflammation, proliferative responses and neovascularization. In large-scale cardiovascular outcome trials, enhanced GLP-1 signaling has reduced the risk of atherosclerotic ischemic events, potentially because GLP-1 retards the growth and increases the stability of atherosclerotic plaques. However, DPP-4 inhibitors have not reduced the risk of major adverse cardiovascular events, possibly because potentiation of SDF-1 enhances plaque growth and instability, activates deleterious neurohormonal mechanisms, and promotes cardiac inflammation and fibrosis. Similarly, trials with GLP-1 agonists and sodium-glucose cotransporter 2 inhibitors have reported favorable effects on renal function, even after only 3-4 years of treatment. In contrast, no benefits on the rate of decline in glomerular filtration rate have been seen in trials of DPP-4 inhibitors, perhaps because the renal actions of DPP-4 inhibitors are primarily mediated by potentiation of SDF-1, not GLP-1. Experimentally, SDF-1 can promote podocyte injury and glomerulosclerosis. Furthermore, the natriuretic action of SDF-1 occurs primarily in the distal tubules, where it cannot utilize tubuloglomerular feedback to modulate the deleterious effects of glomerular hyperfiltration. Potentiation of SDF-1 in experimental models may also exacerbate both retinopathy and neuropathy. Therefore, although DPP-4 inhibitors have attractive clinical features, the benefits that might be expected from GLP-1 signaling may be undermined by their actions to enhance SDF-1.

Diabetic retinopathy: current understanding, mechanisms, and treatment strategies

Diabetic retinopathy (DR) causes significant visual loss on a global scale. Treatments for the vision-threatening complications of diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) have greatly improved over the past decade. However, additional therapeutic options are needed that take into account pathology associated with vascular, glial, and neuronal components of the diabetic retina. Recent work indicates that diabetes markedly impacts the retinal neurovascular unit and its interdependent vascular, neuronal, glial, and immune cells. This knowledge is leading to identification of new targets and therapeutic strategies for preventing or reversing retinal neuronal dysfunction, vascular leakage, ischemia, and pathologic angiogenesis. These advances, together with approaches embracing the potential of preventative or regenerative medicine, could provide the means to better manage DR, including treatment at earlier stages and more precise tailoring of treatments based on individual patient variations.

TPL2 (Therapeutic Targeting Tumor Progression Locus-2)/ATF4 (Activating Transcription Factor-4)/SDF1α (Chemokine Stromal Cell-Derived Factor-α) Axis Suppresses Diabetic Retinopathy

RATIONALE

Diabetic retinopathy is characterized by vasopermeability, vascular leakage, inflammation, blood-retinal barrier breakdown, capillary degeneration, and neovascularization. However, the mechanisms underlying the association between diabetes mellitus and progression retinopathy remain unclear.

OBJECTIVE

TPL2 (tumor progression locus 2), a serine-threonine protein kinase, exerts a pathological effect on vascular angiogenesis. This study investigated the role of N^ε-(carboxymethyl)lysine, a major advanced glycation end products, and the involved TPL2-related molecular signals in diabetic retinopathy using models of in vitro and in vivo and human samples.

METHODS AND RESULTS

Serum N^ε-(carboxymethyl)lysine levels and TPL2 kinase activity were significantly increased in clinical patients and experimental animals with diabetic retinopathy. Intravitreal administration of pharmacological blocker or neutralizing antibody inhibited TPL2 and effectively suppressed the pathological characteristics of retinopathy in streptozotocin-induced diabetic animal models. Intravitreal VEGF (vascular endothelial growth factor) neutralization also suppressed the diabetic retinopathy in diabetic animal models. Mechanistic studies in primary human umbilical vein endothelial cells and primary retinal microvascular endothelial cells from streptozotocin-diabetic rats, db/db mice, and samples from patients with diabetic retinopathy revealed a positive parallel correlation between N^ε-(carboxymethyl)lysine and the TPL2/chemokine SDF1α (stromal cell-derived factor-α) axis that is dependent on endoplasmic reticulum stress-related molecules, especially ATF4 (activating transcription factor-4).

CONCLUSIONS

This study demonstrates that inhibiting the N^ε-(carboxymethyl)lysine-induced TPL2/ATF4/SDF1α axis can effectively prevent diabetes mellitus-mediated retinal microvascular dysfunction. This signaling axis may include the therapeutic potential for other diseases involving pathological neovascularization or macular edema.

Autologous serum supplement favours in vitro regenerative paracrine factors synthesis

OBJECTIVES

Foetal bovine serum (FBS) is often the serum supplement of choice for in vitro human cell culture. This study compares the effect of FBS and autologous human serum (AuHS) supplement in human peripheral blood mononuclear cell (PBMC) culture to prepare secretome.

MATERIALS AND METHODS

The PBMC (n = 7) were cultured either in RPMI-1640 containing L-glutamine and 50 units/ml Penicillin-Streptomycin (BM) or in BM with either AuHS or FBS. Viability, proliferation and differentiation of PBMC were evaluated. Paracrine factors present in the secretomes (n = 6) were analysed using ProcartaPlex Human Cytokine panel (17 plex). Ingenuity Pathway Analysis (IPA) was performed to predict activation or inhibition of biological functions related to tissue regeneration.

RESULTS

The viability of PBMC that were cultured with FBS supplement was significantly reduced at 96 h compared to those at 0 and 24 h (P < .05). While the reduction of the viability of PBMC that were cultured with AuHS supplement was not significantly different compared to those at 0 and 24 h. The FBS secretomes prepared at 24 h was found to contain significantly higher amount of EGF (P < .05) compared to that in AuHS or BM secretome. The AuHS secretomes contained significantly higher amount of HGF at 24 (P < .05) and 96 h (P < .01), and VEGF-A at 24 h (P < .05) compared to those in the FBS secretomes. SDF-1 was not detected in the FBS secretomes prepared at either 24 or 96 hours. Double immunocytochemical staining revealed a marked increase in co-localization of SDF-1 and its receptor in PBMC that were cultured with AuHS supplement compared to that cultured with FBS supplement.

CONCLUSION

In secretome preparation, AuHS supplement favours synthesis of paracrine factors that are needed for regenerative therapy.

MicroRNA-126 and micro-/macrovascular complications of type 1 diabetes in the EURODIAB Prospective Complications Study

AIMS

Increasing evidence suggests a potential role of circulating miRNAs as clinical biomarkers, and loss of miRNA-126 has been proposed as a predictor of type 2 diabetes onset. However, a systematic analysis of circulating miRNAs in type 1 diabetic patients with micro-/macrovascular complications has not yet been performed.

METHODS

A cross-sectional nested case-control study from the EURODIAB Prospective Complications Study of 455 type 1 diabetic patients was performed. Case subjects (n = 312) were defined as those with one or more complications of diabetes; control subjects (n = 143) were those with no evidence of any complication. A differential miRNA expression profiling was performed in pooled serum samples from cases and controls. Furthermore, miR-126 levels were quantified by qPCR in all individual samples and associations with diabetic complications investigated.

RESULTS

Twenty-five miRNAs differed in pooled samples from cases and controls. miR-126 levels were significantly lower in case than in control subjects, even after adjustment for age and sex. In logistic regression analyses, miR-126 was negatively associated with all complications (OR = 0.85, 95 % CI 0.75-0.96) as well as with each micro-/macrovascular complication examined separately. This was likely dependent of diabetes as associations were no longer significant after adjustment for both hyperglycemia and diabetes duration. However, a significant 25 % risk reduction, independent of age, sex, A1C, and diabetes duration, was still observed for proliferative retinopathy (OR = 0.75, 95 % CI 0.59-0.95).

CONCLUSIONS

In this large cohort of type 1 diabetic subjects, we found that miR-126 levels are associated with vascular complications of diabetes, particularly with proliferative retinopathy.

Combination of Bevacizumab and NGF Reduces the Risk of Diabetic Retinopathy

Accumulated evidences support diabetic retinopathy is caused by functional and structural alterations in both the microvascular and neuroglial compartments. Here, we explored any beneficial effects of combination of Bevacizumab and NGF to prevent diabetic retinopathy. STZ-induced diabetic rats were randomly grouped into three groups: sham, Bevacizumab and combination group (Bevacizumab + NGF). End of the treatment, vascular abnormality was evaluated by FITC-dextran. Inflammation and angiogenesis factors were also investigated by real-time PCR and western blot. Our results showed both Bevacizumab and the combination could dramatically reduce abnormal vascular permeability and limit the inflammatory and angiogenesis in 6-week diabetic rats. However, the combination indicated better preventive effects in 12-week diabetic rats compared with Bevacizumab alone. Our findings suggest that the combination of Bevacizumab with NGF may be a new method for the preventive intervention of diabetic retinopathy.

Growth Factors in the Pathogenesis of Retinal Neurodegeneration in Diabetes Mellitus

Neurodegeneration is an initial process in the development of diabetic retinopathy (DR).

High quantities of glutamate, oxidative stress, induction of the renin-angiotensin system (RAS) and elevated levels of RAGE are crucial elements in the retinal neurodegeneration caused by diabetes mellitus. At least, there is emerging proof to indicate that the equilibrium between the neurotoxic and neuroprotective components will affect the state of the retinal neurons.

Somatostatin (SST), pigment epithelium-derived factor (PEDF), and erythropoietin (Epo) are endogenous neuroprotective peptides that are decreased in the eye of diabetic persons and play an essential role in retinal homeostasis. On the other hand, insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF) are pivotal proteins which participate in the development of new capillaries and finally cause damage to the retinal neurons. During recent years, our knowledge about the function of growth factors in the pathogenesis of retinal neurodegeneration has increased. However, intensive investigations are needed to clarify the basic processes that contribute to retinal neurodegeneration and its association with damage to the capillary blood vessels. The objective of this review article is to show new insights on the role of neurotransmitters and growth factors in the pathogenesis of diabetic retinopathy. The information contained in this manuscript may provide the basis for novel strategies based on the factors of neurodegeneration to diagnose, prevent and treat DR in its earliest phases.

The DPP4 Inhibitor Linagliptin Protects from Experimental Diabetic Retinopathy

Background/aims

Dipeptidyl peptidase 4 (DPP4) inhibitors improve glycemic control in type 2 diabetes, however, their influence on the retinal neurovascular unit remains unclear.

Methods

Vasculo- and neuroprotective effects were assessed in experimental diabetic retinopathy and high glucose-cultivated C. elegans, respectively. In STZ-diabetic Wistar rats (diabetes duration of 24 weeks), DPP4 activity (fluorometric assay), GLP-1 (ELISA), methylglyoxal (LC-MS/MS), acellular capillaries and pericytes (quantitative retinal morphometry), SDF-1a and heme oxygenase-1 (ELISA), HMGB-1, Iba1 and Thy1.1 (immunohistochemistry), nuclei in the ganglion cell layer, GFAP (western blot), and IL-1beta, Icam1, Cxcr4, catalase and beta-actin (quantitative RT-PCR) were determined. In C. elegans, neuronal function was determined using worm tracking software.

Results

Linagliptin decreased DPP4 activity by 77% and resulted in an 11.5-fold increase in active GLP-1. Blood glucose and HbA_1c were reduced by 13% and 14% and retinal methylglyoxal by 66%. The increase in acellular capillaries was diminished by 70% and linagliptin prevented the loss of pericytes and retinal ganglion cells. The rise in Iba-1 positive microglia was reduced by 73% with linagliptin. In addition, the increase in retinal Il1b expression was decreased by 65%. As a functional correlate, impairment of motility (body bending frequency) was significantly prevented in C. elegans.

Conclusion

Our data suggest that linagliptin has a protective effect on the microvasculature of the diabetic retina, most likely due to a combination of neuroprotective and antioxidative effects of linagliptin on the neurovascular unit.

Extended time-lapse in vivo imaging of tibia bone marrow to visualize dynamic hematopoietic stem cell engraftment

Homing, engraftment and proliferation of hematopoietic stem/progenitor cell (HSC/HPCs) are crucial steps required for success of a bone marrow transplant. Observation of these critical events is limited by the opaque nature of bone. Here we demonstrate how individual HSCs engraft in long bones by thinning one side of the tibia for direct and unbiased observation. Intravital imaging enabled detailed visualization of single Sca-1⁺, c-Kit⁺, Lineage⁻ (SKL) cell migration to bone marrow niches and subsequent proliferation to reconstitute hematopoiesis. This longitudinal study allowed direct observation of dynamic HSC/HPC activities during engraftment in full color for up to six days in live recipients. Individual SKL cells, but not mature or committed progenitor cells, preferentially homed to a limited number of niches near highly vascularized endosteal regions, and clonally expanded. Engraftment of SKL cells in P-selectin and osteopontin knockout mice showed abnormal homing and expansion of SKL cells. CD150⁺, CD48⁻ SKL populations initially engrafted in the central marrow region, utilizing only a subset of niches occupied by the parent SKL cells. Our study demonstrates that time-lapse imaging of tibia can be a valuable tool to understand the dynamic characteristics of functional HSC and niche components in various mouse models.

Stromal Cell-Derived Factor 1 Polymorphism in Retinal Vein Occlusion

Background

Stromal cell-derived factor 1 (SDF1) has crucial role in the regulation of angiogenesis and ocular neovascularisation (NV). The purpose of this study was to evaluate the association between SDF1-3’G(801)A polymorphism and NV complications of retinal vein occlusion (RVO).

Methods

130 patients with RVO (median age: 69.0, range 35–93 years; male/female– 58/72; 55 patients had central RVO, 75 patients had branch RVO) were enrolled in this study. In the RVO group, 40 (30.8%) patients were diagnosed with NV complications of RVO and 90 (69.2%) patients without NVs. The median follow up period was 40.3 months (range: 18–57 months). The SDF1-3’G(801)A polymorphism was detected by PCR-RFLP. Allelic prevalence was related to reference values obtained in the control group consisted of 125 randomly selected, age and gender matched, unrelated volunteers (median age: 68.0, range 36–95 years; male/female– 53/72). Statistical analysis of the allele and genotype differences between groups (RVO patients vs controls; RVO patients with NV vs RVO patients without NV) was determined by chi-squared test. P value of <0.05 was considered statistically significant.

Results

Hardy-Weinberg criteria was fulfilled in all groups. The SDF1-3’G(801)A allele and genotype frequencies of RVO patients were similar to controls (SDF1-3’A allele: 22.3% vs 20.8%; SDF1-3’(801)AA: 5.4% vs 4.8%, SDF1-3’(801)GG: 60.8% vs 63.2%). The frequency of SDF1-3’(801)AA and SDF1-3’(801)GA genotypes, as well as the SDF1-3’(801)A allele frequency were higher in RVO patients with NV versus in patients without NV complication (SDF1-3’(801)AA+AG genotypes: 57.5% vs 31.1%, p = 0.008; SDF1-3’(801)A allele: 35.0% vs 16.7%, p = 0.002) or versus controls (SDF1-3’(801)AA+AG genotypes 57.5% vs 36.8%, p = 0.021; SDF1-3’(801)A allele: 35.0% vs 20.8% p = 0.01). Carrying of SDF1-3’(801)A allele increased the risk of neovascularisation complications of RVO by 2.69 (OR, 95% CI = 1.47–4.93).

Conclusion

These findings suggest that carrying SDF1-3’(801)A allele plays a role in the development of neovascular complications in retinal vein occlusion.