The 10q26 Risk Haplotype of Age-Related Macular Degeneration Aggravates Subretinal Inflammation by Impairing Monocyte Elimination.

A minor haplotype of the 10q26 locus conveys the strongest genetic risk for age-related macular degeneration (AMD). Here, we examined the mechanisms underlying this susceptibility. We found that monocytes from homozygous carriers of the 10q26 AMD-risk haplotype expressed high amounts of the serine peptidase HTRA1, and HTRA1 located to mononuclear phagocytes (MPs) in eyes of non-carriers with AMD. HTRA1 induced the persistence of monocytes in the subretinal space and exacerbated pathogenic inflammation by hydrolyzing thrombospondin 1 (TSP1), which separated the two CD47-binding sites within TSP1 that are necessary for efficient CD47 activation. This HTRA1-induced inhibition of CD47 signaling induced the expression of pro-inflammatory osteopontin (OPN). OPN expression increased in early monocyte-derived macrophages in 10q26 risk carriers. In models of subretinal inflammation and AMD, OPN deletion or pharmacological inhibition reversed HTRA1-induced pathogenic MP persistence. Our findings argue for the therapeutic potential of CD47 agonists and OPN inhibitors for the treatment of AMD.

Complement Factor H Inhibits CD47-Mediated Resolution of Inflammation.

Variants of the CFH gene, encoding complement factor H (CFH), show strong association with age-related macular degeneration (AMD), a major cause of blindness. Here, we used murine models of AMD to examine the contribution of CFH to disease etiology. Cfh deletion protected the mice from the pathogenic subretinal accumulation of mononuclear phagocytes (MP) that characterize AMD and showed accelerated resolution of inflammation. MP persistence arose secondary to binding of CFH to CD11b, which obstructed the homeostatic elimination of MPs from the subretinal space mediated by thrombospsondin-1 (TSP-1) activation of CD47. The AMD-associated CFH(H402) variant markedly increased this inhibitory effect on microglial cells, supporting a causal link to disease etiology. This mechanism is not restricted to the eye, as similar results were observed in a model of acute sterile peritonitis. Pharmacological activation of CD47 accelerated resolution of both subretinal and peritoneal inflammation, with implications for the treatment of chronic inflammatory disease.

Obesity triggers tumoral senescence and renders poorly immunogenic malignancies amenable to senolysis.

Obesity is a major risk factor for cancer. Conventional thought suggests that elevated adiposity predisposes to heightened inflammatory stress and potentiates tumor growth, yet underlying mechanisms remain ill-defined. Here, we show that tumors from patients with a body mass index >35 carry a high burden of senescent cells. In mouse syngeneic tumor models, we correlated a pronounced accretion of senescent cancer cells with poorly immunogenic tumors when mice were subjected to diet-induced obesity (DIO). Highly immunogenic tumors showed lesser senescence burden suggesting immune-mediated elimination of senescent cancer cells, likely targeted as a consequence of their senescence-associated secretory phenotype. Treatment with the senolytic BH3 mimetic small molecule inhibitor ABT-263 selectively stalled tumor growth in mice with DIO to rates comparable to regular diet-fed mice. Thus, consideration of body adiposity in the selection of cancer therapy may be a critical determinant for disease outcome in poorly immunogenic malignancies.

HIF1α-dependent hypoxia response in myeloid cells requires IRE1α.

Cellular adaptation to low oxygen tension triggers primitive pathways that ensure proper cell function. Conditions of hypoxia and low glucose are characteristic of injured tissues and hence successive waves of inflammatory cells must be suited to function under low oxygen tension and metabolic stress. While Hypoxia-Inducible Factor (HIF)-1α has been shown to be essential for the inflammatory response of myeloid cells by regulating the metabolic switch to glycolysis, less is known about how HIF1α is triggered in inflammation. Here, we demonstrate that cells of the innate immune system require activity of the inositol-requiring enzyme 1α (IRE1α/XBP1) axis in order to initiate HIF1α-dependent production of cytokines such as IL1ß, IL6 and VEGF-A. Knockout of either HIF1α or IRE1α in myeloid cells ameliorates vascular phenotypes in a model of retinal pathological angiogenesis driven by sterile inflammation. Thus, pathways associated with ER stress, in partnership with HIF1α, may co-regulate immune adaptation to low oxygen.

eNOS controls angiogenic sprouting and retinal neovascularization through the regulation of endothelial cell polarity.

The roles of nitric oxide (NO) and endothelial NO synthase (eNOS) in the regulation of angiogenesis are well documented. However, the involvement of eNOS in the sprouting of endothelial tip-cells at the vascular front during sprouting angiogenesis remains poorly defined. In this study, we show that downregulation of eNOS markedly inhibits VEGF-stimulated migration of endothelial cells but increases their polarization, as evidenced by the reorientation of the Golgi in migrating monolayers and by the fewer filopodia on tip cells at ends of sprouts in endothelial cell spheroids. The effect of eNOS inhibition on EC polarization was prevented in Par3-depleted cells. Importantly, downregulation of eNOS increased the expression of polarity genes, such as PARD3B, PARD6A, PARD6B, PKCΖ, TJP3, and CRB1 in endothelial cells. In retinas of eNOS knockout mice, vascular development is retarded with decreased vessel density and vascular branching. Furthermore, tip cells at the extremities of the vascular front have a marked reduction in the number of filopodia per cell and are more oriented. In a model of oxygen-induced retinopathy (OIR), eNOS deficient mice are protected during the initial vaso-obliterative phase, have reduced pathological neovascularization, and retinal endothelial tip cells have fewer filopodia. Single-cell RNA sequencing of endothelial cells from OIR retinas revealed enrichment of genes related to cell polarity in the endothelial tip-cell subtype of eNOS deficient mice. These results indicate that inhibition of eNOS alters the polarity program of endothelial cells, which increases cell polarization, regulates sprouting angiogenesis and normalizes pathological neovascularization during retinopathy.

NOTCH1 signaling induces pathological vascular permeability in diabetic retinopathy.

Diabetic macular edema is a major complication of diabetes resulting in loss of central vision. Although heightened vessel leakiness has been linked to glial and neuronal-derived factors, relatively little is known on the mechanisms by which mature endothelial cells exit from a quiescent state and compromise barrier function. Here we report that endothelial NOTCH1 signaling in mature diabetic retinas contributes to increased vascular permeability. By providing both human and mouse data, we show that NOTCH1 ligands JAGGED1 and DELTA LIKE-4 are up-regulated secondary to hyperglycemia and activate both canonical and rapid noncanonical NOTCH1 pathways that ultimately disrupt endothelial adherens junctions in diabetic retinas by causing dissociation of vascular endothelial-cadherin from ß-catenin. We further demonstrate that neutralization of NOTCH1 ligands prevents diabetes-induced retinal edema. Collectively, these results identify a fundamental process in diabetes-mediated vascular permeability and provide translational rational for targeting the NOTCH pathway (primarily JAGGED1) in conditions characterized by compromised vascular barrier function.

The protein tyrosine phosphatase PTPRJ/DEP-1 contributes to the regulation of the Notch-signaling pathway and sprouting angiogenesis.

The Dll4-Notch-signaling pathway regulates capillary sprouting via the specification of endothelial tip cells. While VEGF is a potent inducer of Dll4 expression, the intracellular mediators that stimulate its expression remain poorly defined. The protein tyrosine phosphatase PTPRJ/DEP-1 is required for angiogenesis in normal or pathological contexts through its modulation of VEGF signaling. Here, we show that in DEP-1 KO mice, retinas at post-natal day 5 show enlarged blood vessels, as well as an increased number of tip cells and vessel branching points at the migrating front of the vascular plexus. Consistent with these observations, the proliferation of endothelial cells is increased in the retinas of DEP-1 KO mice, as revealed by phospho-histone H3 staining, and increased phosphorylation of ERK1/2 in HUVECs transfected with DEP-1 siRNA. The expression of Dll4 was decreased in retinas of DEP-1 KO mice and was associated with decreased Notch activation. Mechanistically, reduced Dll4 expression in the absence of DEP-1 was correlated with the inhibition of the Src/Akt/ß-Catenin-signaling pathway in HUVECs. Conversely, overexpression of WT DEP-1 in cultured endothelial cells, but not of mutants unable to activate Src-dependent signaling, promoted Dll4 expression. Inhibition of Src, Akt, and ß-catenin transcriptional activity, leading to the inhibition of Dll4 expression, further suggested that their activation through a DEP-1-dependent pathway was required to promote Dll4 expression in VEGF-stimulated endothelial cells. Altogether, these data demonstrate that DEP-1, via Akt and ß-catenin, is a significant promoter of the VEGF-induced Dll4-Notch pathway, and can contribute to the regulation of the tip and stalk cell phenotypes of endothelial cells.

BMP9 (Bone Morphogenetic Protein-9)/Alk1 (Activin-Like Kinase Receptor Type I) Signaling Prevents Hyperglycemia-Induced Vascular Permeability.

Objective- Diabetic macular edema is a major cause of visual impairment. It is caused by blood-retinal barrier breakdown that leads to vascular hyperpermeability. Current therapeutic approaches consist of retinal photocoagulation or targeting VEGF (vascular endothelial growth factor) to limit vascular leakage. However, long-term intravitreal use of anti-VEGFs is associated with potential safety issues, and the identification of alternative regulators of vascular permeability may provide safer therapeutic options. The vascular specific BMP (bone morphogenetic protein) receptor ALK1 (activin-like kinase receptor type I) and its circulating ligand BMP9 have been shown to be potent vascular quiescence factors, but their role in the context of microvascular permeability associated with hyperglycemia has not been evaluated. Approach and Results- We investigated Alk1 signaling in hyperglycemic endothelial cells and assessed whether BMP9/Alk1 signaling could modulate vascular permeability. We show that high glucose concentrations impair Alk1 signaling, both in cultured endothelial cells and in a streptozotocin model of mouse diabetes mellitus. We observed that Alk1 signaling participates in the maintenance of vascular barrier function, as Alk1 haploinsufficiency worsens the vascular leakage observed in diabetic mice. Conversely, sustained delivery of BMP9 by adenoviral vectors significantly decreased the loss of retinal barrier function in diabetic mice. Mechanistically, we demonstrate that Alk1 signaling prevents VEGF-induced phosphorylation of VE-cadherin and induces the expression of occludin, thus strengthening vascular barrier functions. Conclusions- From these data, we suggest that by preventing retinal vascular permeability, BMP9 could serve as a novel therapeutic agent for diabetic macular edema.

In Vivo Laser-Mediated Retinal Ganglion Cell Optoporation Using KV1.1 Conjugated Gold Nanoparticles.

Vision loss caused by retinal diseases affects hundreds of millions of individuals worldwide. The retina is a delicate central nervous system tissue stratified into layers of cells with distinct roles. Currently, there is a void in treatments that selectively target diseased retinal cells, and current therapeutic paradigms present complications associated with off-target effects. Herein, as a proof of concept, we introduce an in vivo method using a femtosecond laser to locally optoporate retinal ganglion cells (RGCs) targeted with functionalized gold nanoparticles (AuNPs). We provide evidence that AuNPs functionalized with an antibody toward the cell-surface voltage-gated K+ channel subunit KV1.1 can selectively deliver fluorescently tagged siRNAs or fluorescein isothiocyanate-dextran dye into retinal cells when irradiated with an 800 nm 100 fs laser. Importantly, neither AuNP administration nor irradiation resulted in RGC death. This system provides a novel, non-viral-based approach that has the potential to selectively target retinal cells in diseased regions while sparing healthy areas and may be harnessed in future cell-specific therapies for retinal degenerative diseases.

Nogo-A inhibits vascular regeneration in ischemic retinopathy.

Nogo-A is a potent glial-derived inhibitor of axon growth in the injured CNS and acts as a negative regulator of developmental angiogenesis by inhibiting vascular endothelial cell migration. However, its function in pathological angiogenesis has never been studied after ischemic injury in the CNS. Using the mouse model of oxygen-induced retinopathy (OIR) which yields defined zones of retinal ischemia, our goal was to investigate the role of Nogo-A in vascular regeneration. We demonstrate a marked upregulation of the Nogo-A receptor sphingosine 1-phosphate receptor 2 in blood vessels following OIR, while Nogo-A is abundantly expressed in surrounding glial cells. Acute inhibition of Nogo-A with function-blocking antibody 11C7 significantly improved vascular regeneration and consequently prevented pathological pre-retinal angiogenesis. Ultimately, inhibition of Nogo-A led to restoration of retinal function as determined by electrophysiological response of retinal cells to light stimulation. Our data suggest that anti-Nogo-A antibody may protect neuronal cells from ischemic damage by accelerating blood vessel repair in the CNS. Targeting Nogo-A by immunotherapy may improve CNS perfusion after vascular injuries.

VEGF Requires the Receptor NRP-1 To Inhibit Lipopolysaccharide-Dependent Dendritic Cell Maturation.

To stimulate a productive T cell response, dendritic cells (DC) must undergo maturation characterized by heightened cell surface expression of MHC and costimulatory molecules as well as cytokine production. Conversely, the inhibition of DC maturation is a central mechanism of immune tolerance. The control of the DC maturation process relies on the integration of several cellular stimulatory or inhibitory signals. The soluble factors and their receptors controlling this central aspect of DC biology are incompletely characterized. We show that murine bone marrow-derived DC (BMDC) maturation induced by LPS, as opposed to polyinosinic:polycytidylic acid or cytosine-phosphate-guanine, is robustly inhibited by vascular endothelial growth factor (VEGF), a previously identified immunosuppressive cytokine. Using BMDC from wild type and conditional knockout mice, we show that neuropilin-1 (NRP-1), a known receptor of VEGF, is necessary to suppress LPS-dependent BMDC maturation. The absence of NRP-1 had no ostensible effects on the biology of BMDC in the absence of VEGF. However, NRP-1-deficient BMDC remained completely insensitive to the VEGF-dependent inhibition of BMDC maturation in culture. In the presence of VEGF, NRP-1 directly interacted with the LPS receptor TLR4 and suppressed downstream signaling through ERK and NF-κß, resulting in a sharp inhibition of MHC class II and costimulatory molecules (CD40, CD86) expression as well as proinflammatory cytokine production. Consequently, we identify NRP-1 as a target to optimize DC maturation within environments that are rich in VEGF, such as tumors.

p75NTR and Its Ligand ProNGF Activate Paracrine Mechanisms Etiological to the Vascular, Inflammatory, and Neurodegenerative Pathologies of Diabetic Retinopathy.

UNLABELLED: In many diseases, expression and ligand-dependent activity of the p75(NTR) receptor can promote pericyte and vascular dysfunction, inflammation, glial activation, and neurodegeneration. Diabetic retinopathy (DR) is characterized by all of these pathological events. However, the mechanisms by which p75(NTR) may be implicated at each stage of DR pathology remain poorly understood. Using a streptozotocin mouse model of diabetic retinopathy, we report that p75(NTR) is upregulated very early in glia and in pericytes to mediate ligand-dependent induction of inflammatory cytokines, disruption of the neuro-glia-vascular unit, promotion of blood-retina barrier breakdown, edema, and neuronal death. In a mouse model of oxygen-induced retinopathy, mimicking proliferative DR, p75(NTR)-dependent inflammation leads to ischemia and pathological angiogenesis through Semaphorin 3A. The acute use of antagonists of p75(NTR) or antagonists of the ligand proNGF suppresses each distinct phase of pathology, ameliorate disease, and prevent disease progression. Thus, our study documents novel disease mechanisms and validates druggable targets for diabetic retinopathy. SIGNIFICANCE STATEMENT: Diabetic retinopathy (DR) affects an estimated 250 million people and has no effective treatment. Stages of progression comprise pericyte/vascular dysfunction, inflammation, glial activation, and neurodegeneration. The pathophysiology of each stage remains unclear. We postulated that the activity of p75NTR may be implicated. We show that p75NTR in glia and in pericytes mediate ligand-dependent induction of inflammatory cytokines, disruption of the neuro-glia-vascular unit, promotion of blood-retina barrier breakdown, edema, and neuronal death. p75NTR-promoted inflammation leads to ischemia and angiogenesis through Semaphorin 3A. Antagonists of p75NTR or antagonists of proNGF suppress each distinct phase of pathology, ameliorate disease, and prevent disease progression. Our study documents novel mechanisms in a pervasive disease and validates druggable targets for treatment.

miRNAs, single nucleotide polymorphisms (SNPs) and age-related macular degeneration (AMD).

Advanced age-related macular degeneration (AAMD) is a complex sight-threating disease of public health significance. Micro RNAs (miRNAs) have been proposed as biomarkers for AAMD. The presence of certain single nucleotide polymorphisms (SNPs) may influence the explanatory value of these biomarkers. Here we present findings from an integrated approach used to determine whether AAMD-associated SNPs have the capacity to influence miRNA-mRNA pairing and, if so, to what extent such pairing may be manifested in a discrete AAMD transcriptome. Using a panel of 8854 SNPs associated with AAMD at p-values ≤5.0E-7 from a cohort of >30,000 elderly people, we identified SNPs in miRNA target-encoding constituents of: (1) regulator of complement activation (RCA) genes (rs390679, CFHR1, p≤2.14E-214 | rs12140421, CFHR3, p≤4.63E-29); (2) genes of major histocompatibility complex (MHC) loci (rs4151672, CFB, p≤8.91E-41 | rs115404146, HLA-C, p≤6.32E-12 | rs1055821, HLA-B, p≤1.93E-9 | rs1063355, HLA-DQB1, p≤6.82E-14); and (3) genes of the 10q26 AAMD locus (rs1045216, PLEKHA1, p≤4.17E-142 | rs2672603, ARMS2, p≤7.14E-46). We used these findings with existing data on AAMD-related retinal miRNA and transcript profiles for the purpose of making inferences on SNP-mRNA-miRNA-AAMD relationships. Four of 12 miRNAs significantly elevated in AAMD retina (hsa-miR-155-5p, hsa-let-7a-5p, hsa-let-7b-5p hsa-let-7d-5p) also showed strong pairing capacity (TarBase 7.1 context++ score <-0.2, miRanda 3.3 pairing score >150) with miRNA target transcripts encoded by AAMD-associated SNPs resident in HLA-DQB1 (rs1063355, hsa-miR-155-5p) and TGFBR1 (rs868, hsa-let-7). Three of the 12 miRNAs overexpressed in AAMD retina are inducible by NFkB and have high affinity targets in the complement factor H (CFH) mRNA 3' UTR. We used ENSEMBL to identify polymorphic regions in the CFH mRNA 3' UTR with the capacity to disrupt miRNA-mRNA pairing. Two variants (rs766666504 and rs459598) existed in DNA sequence encoding the seed region of hsa-miR-146a-5p in the CFH mRNA 3' UTR - as this miRNA is also elevated in both vitreous and serum of people with AAMD, it shows great value as a biomarker. Our findings suggest that knowledge on the nature of DNA sequence variation may increase the explanatory power of miRNA biomarkers in genetically diverse populations, while yielding information with which to develop: (1) mechanistic tests on processes implicated in AMD pathogenesis; and, (2) site-specific small molecules (synthetic mimetics or anti-miRNAs) with preventive or therapeutic efficacy for AAMD.

Neurovascular cross talk in diabetic retinopathy: Pathophysiological roles and therapeutic implications.

Diabetic retinopathy (DR) is the leading cause of blindness in the working-age population in developed countries, and its prevalence will increase as the global incidence of diabetes grows exponentially. DR begins with an early nonproliferative stage in which retinal blood vessels and neurons degenerate as a consequence of chronic hyperglycemia, resulting in vasoregression and persistent retinal ischemia, metabolic disequilibrium, and inflammation. This is conducive to overcompensatory pathological neovascularization associated with advanced proliferative DR. Although DR is considered a microvascular complication, the retinal microvasculature is intimately associated with and governed by neurons and glia; neurodegeneration, neuroinflammation, and dysregulation of neurovascular cross talk are responsible in part for vascular abnormalities in both early nonproliferative DR and advanced proliferative DR. Neuronal activity directly regulates microvascular dilation and blood flow in the process of neurovascular coupling. Retinal neurons also secrete guidance cues in response to injury, ischemia, or metabolic stress that may either promote or suppress vascular outgrowth, either alleviating or exacerbating DR, contingent on the stage of disease and retinal microenvironment. Neurodegeneration, impaired neurovascular coupling, and dysregulation of neuronal guidance cues are key events in the pathogenesis of DR, and correcting these events may prevent or delay development of advanced DR. The review discusses the mechanisms of neurovascular cross talk and its dysregulation in DR, and their potential therapeutic implications.

Retinal neurons curb inflammation and enhance revascularization in ischemic retinopathies via proteinase-activated receptor-2.

Ischemic retinopathies are characterized by sequential vaso-obliteration followed by abnormal intravitreal neovascularization predisposing patients to retinal detachment and blindness. Ischemic retinopathies are associated with robust inflammation that leads to generation of IL-1ß, which causes vascular degeneration and impairs retinal revascularization in part through the liberation of repulsive guidance cue semaphorin 3A (Sema3A). However, retinal revascularization begins as inflammation culminates in ischemic retinopathies. Because inflammation leads to activation of proteases involved in the formation of vasculature, we hypothesized that proteinase-activated receptor (Par)-2 (official name F2rl1) may modulate deleterious effects of IL-1ß. Par2, detected mostly in retinal ganglion cells, was up-regulated in oxygen-induced retinopathy. Surprisingly, oxygen-induced retinopathy-induced vaso-obliteration and neovascularization were unaltered in Par2 knockout mice, suggesting compensatory mechanisms. We therefore conditionally knocked down retinal Par2 with shRNA-Par2-encoded lentivirus. Par2 knockdown interfered with normal revascularization, resulting in pronounced intravitreal neovascularization; conversely, the Par2 agonist peptide (SLIGRL) accelerated normal revascularization. In vitro and in vivo exploration of mechanisms revealed that IL-1ß induced Par2 expression, which in turn down-regulated sequentially IL-1 receptor type I and Sema3A expression through Erk/Jnk-dependent processes. Collectively, our findings unveil an important mechanism by which IL-1ß regulates its own endothelial cytotoxic actions by augmenting neuronal Par2 expression to repress sequentially IL-1 receptor type I and Sema3A expression. Timely activation of Par2 may be a promising therapeutic avenue in ischemic retinopathies.

SYK is a target of lymphocyte-derived microparticles in the induction of apoptosis of human retinoblastoma cells.

Retinoblastoma (Rb) is an aggressive childhood cancer of the developing retina. This disease is associated with epigenetic deregulation of several cancer pathways including upregulation of the proto-oncogene spleen tyrosine kinase (SYK). We have previously demonstrated that lymphocyte-derived microparticles (LMPs) possess strong cytotoxic effect on cancer cells. This report demonstrated that LMPs have potent pro-apoptotic properties on human Rb cells, which was associated with a strong reduction of SYK expression. Perturbing SYK activity in Rb cells induced cell apoptosis and upregulated expression of p53 and p21. Interestingly, inhibition of p53 or knockdown of p21, abolished LMP-induced caspase-3 activity and cell death. Blocking oxidized phospholipid-rich LMPs with a specific antibody significantly prevented LMP-induced Rb apoptosis and reversed the expression patterns of SYK, p53, p21. In summary, our results suggest that LMPs are important pro-apoptotic regulators for Rb cells through reduction of SYK expression and upregulation of the p53-p21 pathway which ultimately activates caspase-3. These data may open unexpected avenues for the development of LMPs as a novel therapeutic strategy that would be particularly useful and relevant for the treatment of Rb.

Cytochrome P450 2C8 ω3-long-chain polyunsaturated fatty acid metabolites increase mouse retinal pathologic neovascularization--brief report.

OBJECTIVE: Regulation of angiogenesis is critical for many diseases. Specifically, pathological retinal neovascularization, a major cause of blindness, is suppressed with dietary ω3-long-chain polyunsaturated fatty acids (ω3LCPUFAs) through antiangiogenic metabolites of cyclooxygenase and lipoxygenase. Cytochrome P450 epoxygenases (CYP2C8) also metabolize LCPUFAs, producing bioactive epoxides, which are inactivated by soluble epoxide hydrolase (sEH) to transdihydrodiols. The effect of these enzymes and their metabolites on neovascularization is unknown. APPROACH AND RESULTS: The mouse model of oxygen-induced retinopathy was used to investigate retinal neovascularization. We found that CYP2C (localized in wild-type monocytes/macrophages) is upregulated in oxygen-induced retinopathy, whereas sEH is suppressed, resulting in an increased retinal epoxide:diol ratio. With a ω3LCPUFA-enriched diet, retinal neovascularization increases in Tie2-driven human-CYP2C8-overexpressing mice (Tie2-CYP2C8-Tg), associated with increased plasma 19,20-epoxydocosapentaenoic acid and retinal epoxide:diol ratio. 19,20-Epoxydocosapentaenoic acids and the epoxide:diol ratio are decreased with overexpression of sEH (Tie2-sEH-Tg). Overexpression of CYP2C8 or sEH in mice does not change normal retinal vascular development compared with their wild-type littermate controls. The proangiogenic role in retina of CYP2C8 with both ω3LCPUFA and ω6LCPUFA and antiangiogenic role of sEH in ω3LCPUFA metabolism were corroborated in aortic ring assays. CONCLUSIONS: Our results suggest that CYP2C ω3LCPUFA metabolites promote retinal pathological angiogenesis. CYP2C8 is part of a novel lipid metabolic pathway influencing retinal neovascularization.

Eyeing central neurons in vascular growth and reparative angiogenesis.

The generation of blood vessels is a highly synchronized process requiring the coordinated efforts of several vascular and nonvascular cell populations as well as a stringent orchestration by the tissue being vascularized. Stereotyped angiogenesis is vital for both developmental growth and to restore tissue metabolic supply after ischemic events. Central neurons such as those found in the brain, spinal cord, and retina are vast consumers of oxygen and nutrients and therefore require high rates of perfusion by functional vascular networks to ensure proper sensory transmission. During a metabolic mismatch, such as that occurring during a cerebrovascular infarct or in ischemic retinopathies, there is increasing evidence that central neurons have an inherent ability to influence the vascular response to injury. With a focus on the retina and retinal ischemic disorders, this review explores the ever-growing evidence suggesting that central neurons have the propensity to impact tissue vascularization and reparative angiogenesis. Moreover, it addresses the paradoxical ability of severely ischemic neurons to hinder vascular regrowth and thus segregate the most severely injured zones of nervous tissue. The topics covered here are pertinent for future therapeutic strategies because promoting and steering vascular growth may be beneficial for ischemic disorders.

SOCS3 is an endogenous inhibitor of pathologic angiogenesis.

Inflammatory cytokines and growth factors drive angiogenesis independently; however, their integrated role in pathologic and physiologic angiogenesis is not fully understood. Suppressor of cytokine signaling-3 (SOCS3) is an inducible negative feedback regulator of inflammation and growth factor signaling. In the present study, we show that SOCS3 curbs pathologic angiogenesis. Using a Cre/Lox system, we deleted SOCS3 in vessels and studied developmental and pathologic angiogenesis in murine models of oxygen-induced retinopathy and cancer. Conditional loss of SOCS3 leads to increased pathologic neovascularization, resulting in pronounced retinopathy and increased tumor size. In contrast, physiologic vascularization is not regulated by SOCS3. In vitro, SOCS3 knockdown increases proliferation and sprouting of endothelial cells costimulated with IGF-1 and TNFα via reduced feedback inhibition of the STAT3 and mTOR pathways. These results identify SOCS3 as a pivotal endogenous feedback inhibitor of pathologic angiogenesis and a potential therapeutic target acting at the converging crossroads of growth factor- and cytokine-induced vessel growth.

Evaluation of the vitreous microbial contamination rate in office-based three-port microincision vitrectomy surgery using Retrector technology.

BACKGROUND: To perform a microbiological contamination analysis of the vitreous during office-based micro-incision vitrectomy surgery (MIVS) assessing whether the bacteria detected correlated with patient's ocular conjunctival flora. METHODS: This is a prospective, interventional, nonrandomized case series of patients undergoing office-based MIVS, anti-VEGF, and dexamethasone intravitreal injections (triple therapy) for the treatment of wet age-related macular degeneration (AMD) and diabetic macular edema (DME).All patients were operated at a small procedure room in an ambulatory clinic of the Department of Ophthalmology, University of Montreal, Quebec, Canada. Conjunctival samples were done before placing the sclerotomies. The MIVS was done with a 23-gauge retractable vitrector, a 27-gauge infusion line, and a 29-gauge chandelier. Undiluted and diluted vitreous were collected for aerobic, anaerobic and fungal cultures. Outcomes measured were bacterial species identification within samples collected from the conjunctiva and the vitreous. RESULTS: Thirty-seven patients (37 eyes) were recruited and completed over 17 months of follow-up. Twenty-eight had wet AMD and nine had DME. There were 13 men and 24 women, with a mean age of 78 years. Eighteen patients (46%) had culture positive conjunctival flora. Twenty-six bacterial colonies were tabulated in total from the conjunctival swabs. All bacteria detected were gram-positive bacteria (100%), most commonly: Staphylococcus epidermitis in 11 (42%) and Corynebacterium sp. in 6 (23%). Only 1/18 patients had more than 3 species isolated, 6/18 patients had 2 species and 11/18 patients had 1 species identified on the conjunctival swab. Only 1 of the 37 undiluted midvitreous samples was culture positive, equating to a contamination rate of 2.7%. None of the diluted vitreous samples were culture positive. All cultures were negative for fungus. No serious postoperative complications occurred, including bacterial endophthalmitis, choroidal detachment, and retinal detachment. CONCLUSION: This preliminary study of office-based MIVS gives us insights on the ocular surface microbial profile and vitreous contamination rate of performing such procedures outside the OR-controlled environment. Our initial results seem to indicate that there is little risk of bacterial translocation and contamination from the conjunctiva into the vitreous. Therefore, if endophthalmitis occurs post-operatively, the source may likely arise after the procedure. Larger studies are needed to confirm our data.