Monitoring SpO2: The Basics of Retinopathy of Prematurity (Back to Basics) and Targeting Oxygen Saturation.

Oxygen (O2) is a drug frequently used in newborn care. Adverse effects of hypoxia are well known but the damaging effects of excess oxygen administration and oxidative stress have only been studied in the last 2 decades. Many negative effects have been described, including retinopathy of prematurity . Noninvasive pulse oximetry (SpO2) is useful to detect hypoxemia but requires careful evaluation and understanding of the frequently changing relationship between O2 and hemoglobin to prevent hyperoxemia. Intention to treat SpO2 ranges should be individualized for every newborn receiving supplemental O2, according to gestational age, post-natal age, and clinical condition.

Differences in Oxygen-Induced Retinopathy Susceptibility Between Two Sprague Dawley Rat Vendors: A Comparison of Retinal Transcriptomes.

PURPOSE: To determine the retinal transcriptomic differences underlying the oxygen-induced retinopathy phenotypes between Sprague Dawley rat pups from two commonly used commercial vendors. This will allow us to discover genes and pathways that may be related to differences in disease severity in similarly aged premature babies and suggest possible new treatment approaches. METHODS: We analyzed retinal vascular morphometry and transcriptomes from Sprague Dawley rat pups from Charles River Laboratories and Envigo (previously Harlan). Room air control and oxygen-induced retinopathy groups were compared. Oxygen-induced retinopathy was induced with the rat 50/10 model. RESULTS: Pups from Charles River Laboratories developed a more severe oxygen-induced retinopathy phenotype, with 3.6-fold larger percent avascular area at P15 and twofold larger % neovascular area at P20 than pups from Envigo. Changes in retinal transcriptomes of rat pups from both vendors were substantial at baseline and in response to oxygen-induced retinopathy. Baseline differences centered on activated pathways of neuronal development in Charles River Laboratories pups. In response to oxygen-induced retinopathy, during the neovascular phase, retinas from Charles River Laboratories pups exhibited activation of pathways regulating necrosis, neuroinflammation, and interferon signaling, supporting the observed increase of neovascularization. Conversely, retinas from Envigo pups showed decreased necrosis and increased focal adhesion kinase signaling, supporting more normal vascular development. Comparing oxygen-induced retinopathy transcriptomes at P15 to those at P20, canonical pathways such as phosphate and tensin homolog, interferon, and coordinated lysosomal expression and regulation element signaling were identified, highlighting potential novel mechanistic targets for future research. CONCLUSION: Transcriptomic profiles differ substantially between rat pup retinas from Charles River Laboratories and Envigo at baseline and in response to oxygen-induced retinopathy, providing insight into vascular morphologic differences. Comparing transcriptomes identified new pathways for further research in oxygen-induced retinopathy pathogenesis and increased scientific rigor of this model.

Early Depletion of Neutrophils Reduces Retinal Inflammation and Neovascularization in Mice with Oxygen-Induced Retinopathy.

Retinal inflammation is a central feature of ocular neovascular diseases such as diabetic retinopathy and retinopathy of prematurity, but the contribution of neutrophils to this process is not fully understood. We studied oxygen-induced retinopathy (OIR) which develops in two phases, featuring hyperoxia-induced retinal vaso-obliteration in phase I, followed by retinal neovascularization in phase II. As neutrophils are acute responders to tissue damage, we evaluated whether neutrophil depletion with an anti-Ly6G mAb administered in phase I OIR influenced retinal inflammation and vascular injury. Neutrophils were measured in blood and spleen via flow cytometry, and myeloperoxidase, an indicator of neutrophil activity, was evaluated in the retina using Western blotting. Retinal vasculopathy was assessed by quantitating vaso-obliteration, neovascularization, vascular leakage, and VEGF levels. The inflammatory factors, TNF, MCP-1, and ICAM-1 were measured in retina. In the OIR controls, neutrophils were increased in the blood and spleen in phase I but not phase II OIR. In OIR, the anti-Ly6G mAb reduced neutrophils in the blood and spleen, and myeloperoxidase, inflammation, and vasculopathy in the retina. Our findings revealed that the early rise in neutrophils in OIR primes the retina for an inflammatory and angiogenic response that promotes severe damage to the retinal vasculature.

Limited Hyperoxia-Induced Proliferative Retinopathy (LHIPR) as a Model of Retinal Fibrosis, Angiogenesis, and Inflammation.

The progression to fibrosis and traction in retinopathy of prematurity (ROP) and other ischemic retinopathies remains an important clinical and surgical challenge, necessitating a comprehensive understanding of its pathogenesis. Fibrosis is an unbalanced deposition of extracellular matrix components responsible for scar tissue formation with consequent tissue and organ impairment. Together with retinal traction, it is among the main causes of retinal detachment and vision loss. We capitalize on the Limited Hyperoxia Induced Retinopathy (LHIPR) model, as it reflects the more advanced pathological phenotypes seen in ROP and other ischemic retinopathies. To model LHIPR, we exposed wild-type C57Bl/6J mouse pups to 65% oxygen from P0 to P7. Then, the pups were returned to room air to recover until later endpoints. We performed histological and molecular analysis to evaluate fibrosis progression, angiogenesis, and inflammation at several time points, from 1.5 months to 9 months. In addition, we performed in vivo retinal imaging by optical coherence tomography (OCT) or OCT Angiography (OCTA) to follow the fibrovascular progression in vivo. Although the retinal morphology was relatively preserved, we found a progressive increase in preretinal fibrogenesis over time, up to 9 months of age. We also detected blood vessels in the preretinal space as well as an active inflammatory process, altogether mimicking advanced preretinal fibrovascular disease in humans.

Identification and validation of lactate metabolism-related genes in oxygen-induced retinopathy.

Retinopathy of Prematurity (ROP) is a multifactorial disease characterized by abnormal retinal vascular growth in premature infants, which is one of the leading causes of childhood blindness. Lactic acid metabolism may play an imperative role in the development of ROP, but there are still few relevant studies. Our team use a dataset GSE158799 contained 284 genes in 3 P17_OIR mice and 3 P30_OIR mice to identify 41 potentially differentially expressed lactate metabolism-related genes (LMRGs) related to ROP. Then through bioinformatics analysis, we strive to reveal the interaction, the enriched pathways and the immune cell infiltration among these LMRGs, and predict their functions and internal mechanisms. These DEGs may regulate lactate metabolism, leading to the changes of metabolism and immunity, thereby inducing the development of ROP. Our results will expand our understanding of the intrinsic mechanism of ROP and may be helpful for the directions for treatment of ROP in the future.

Proteomics Analysis of R-Ras Deficiency in Oxygen Induced Retinopathy.

Small GTPase R-Ras regulates vascular permeability in angiogenesis. In the eye, abnormal angiogenesis and hyperpermeability are the leading causes of vision loss in several ischemic retinal diseases such as proliferative diabetic retinopathy (PDR), retinal vein occlusion (RVO), and retinopathy of prematurity (ROP). Oxygen-induced retinopathy (OIR) is the most widely used experimental model for these ischemic retinopathies. To shed more light on how the R-Ras regulates vascular permeability in pathological angiogenesis, we performed a comprehensive (>2900 proteins) characterization of OIR in R-Ras knockout (KO) and wild-type (WT) mice by sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomics. OIR and age-matched normoxic control retinas were collected at P13, P17, and P42 from R-Ras KO and WT mice and were subjected to SWATH-MS and data analysis. The most significant difference between the R-Ras KO and WT retinas was an accumulation of plasma proteins. The pathological vascular hyperpermeability during OIR in the R-Ras KO retina took place very early, P13. This led to simultaneous hypoxic cell injury/death (ferroptosis), glycolytic metabolism as well compensatory mechanisms to counter the pathological leakage from angiogenic blood vessels in the OIR retina of R-Ras deficient mice.

Prenatal Carotenoid Supplementation With Lutein or Zeaxanthin Ameliorates Oxygen-Induced Retinopathy (OIR) in Bco2-/- Macular Pigment Mice.

Purpose: Premature infants at risk of retinopathy of prematurity (ROP) miss placental transfer of the carotenoids lutein (L) and zeaxanthin (Z) during the third trimester. We previously demonstrated that prenatal L and Z supplementation raised carotenoid levels in infants at birth in the Lutein and Zeaxanthin in Pregnancy (L-ZIP) study (NCT03750968). Based on their antioxidant effects and bioavailability, we hypothesized that prenatal maternal supplementation with macular carotenoids would reduce the risk of ROP. To test this hypothesis, we utilized "macular pigment mice" genetically engineered to take up L and Z into the retina in a model of oxygen-induced retinopathy (OIR). Methods: Pregnant Bco2-/- mice were divided into nine experimental subgroups based on the type of supplementation (L, Z, or placebo) and on the maternal supplementation start date corresponding to the three trimesters of human fetal development (E0, E11, and P1). Pups and nursing mothers were exposed to 75% O2 for 5 days (P7-P12) and returned to room air for 5 days (P12-P17). Pups were killed at P12 and P17, and their retinas were analyzed for vaso-obliteration and intravitreal neovascularization. Results: Pups of pregnant mice supplemented with L or Z had significant reductions in areas of vaso-obliteration and intravitreal neovascularization compared to placebo. Prenatal carotenoid supplementation starting at E0 or E11 was significantly more protective against OIR than postnatal supplementation starting at P1. Conclusions: Prenatal supplementation with L and Z was beneficial in a mouse OIR model. We recommend testing prenatal L and Z supplementation in future human clinical trials to prevent ROP.

Identification of reference genes for the normalization of retinal mRNA expression by RT-qPCR in oxygen induced retinopathy, anemia, and erythropoietin administration.

BACKGROUND: Anemia and retinopathy of prematurity (ROP) are common comorbidities experienced by preterm infants, yet the role of anemia on the pathogenesis of ROP remains unclear. Reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) is a sensitive technique for estimating the gene expression changes at the transcript level but requires identification of stably expressed reference genes for accurate data interpretation. This is particularly important for oxygen induced retinopathy studies given that some commonly used reference genes are sensitive to oxygen. This study aimed to identify stably expressed reference genes among eight commonly used reference genes in the neonatal rat pups' retina upon exposure to cyclic hyperoxia-hypoxia, anemia, and erythropoietin administration at two age groups (P14.5 and P20) using Bestkeeper, geNorm, and Normfinder, three publicly available, free algorithms, and comparing their results to the in-silico prediction program, RefFinder. RESULTS: The most stable reference gene across both developmental stages was Rpp30, as predicted by Genorm, Bestkeeper, and Normfinder. RefFinder predicted Tbp to be the most stable across both developmental stages. At P14.5, stability varied by prediction program; at P20, RPP30 and MAPK1 were the most stable reference genes. Gapdh, 18S, Rplp0, and HPRT were predicted as the least stable reference genes by at least one of the prediction algorithms. CONCLUSION: Expression of Rpp30 is the least affected by experimental conditions of oxygen induced retinopathy, phlebotomy induced anemia and erythropoietin administration at both timepoints of P14.5 and P20.

Safety and Efficacy of Systemic Anti-Scg3 Therapy to Treat Oxygen-Induced Retinopathy.

BACKGROUND: To circumvent possible systemic side effects, anti-angiogenic drugs targeting vascular endothelial growth factor (VEGF) for ocular neovascular diseases in adults are approved only for intravitreal administration. However, intravitreal injection itself can elicit injection-related adverse effects, and premature eyes of infants with retinopathy of prematurity (ROP) may be particularly susceptible to intravitreal injection. Therefore, an unmet clinical need is to develop safe systemic anti-angiogenic therapies for ROP. We recently reported that secretogranin III (Scg3) is a disease-restricted angiogenic factor and that systemic anti-Scg3 mAb alleviates ROP in animal models with minimal side effects on developing eyes and organs. The aim of this study is to investigate the safety and efficacy of a humanized anti-Scg3 antibody via systemic administration. METHODS: We analyzed the safety and efficacy of a humanized anti-Scg3 antibody Fab fragment (hFab) delivered by intraperitoneal injection in oxygen-induced retinopathy (OIR) mice, a surrogate model of ROP. RESULTS: The results showed that systemic anti-Scg3 hFab effectively alleviated pathological retinal neovascularization in OIR mice with similar efficacy to the anti-VEGF drug aflibercept. Systemic aflibercept conferred significant adverse side effects in neonatal mice, including reduced body weight, abnormalities in retinal and renal development, and retarded physiological neovascularization, whereas systemic anti-Scg3 hFab elicited no such side effects. CONCLUSIONS: The findings suggest that systemic anti-Scg3 hFab is a safe and effective therapy for OIR and support further development for ROP treatment.

7, 8-Dihydroxyflavone, a TrkB receptor agonist, provides minimal protection against retinal vascular damage during oxygen-induced ischemic retinopathy.

Retinopathy of prematurity (ROP) is one of the main causes of blindness in children worldwide. Brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB), play critical protective roles in the development and function of neurons and vasculature. Lack of BDNF expression results in increased endothelial cell apoptosis and reduced endothelial cell-cell contact. Premature babies who develop ROP tend to have lower serum BDNF levels. BDNF expression is also significantly lower in mouse retinas following exposure to hyperoxia compared to those reared in room air. Specifically, BDNF promotes angiogenic tube formation of endothelial cells (EC), and it is considered an EC survival factor required for stabilization of intramyocardial vessels. We hypothesized that the activation of TrkB receptor protects retinal vasculature in the mice during oxygen-induced ischemic retinopathy (OIR), a model of ROP. To test this hypothesis, we treated neonatal mice with 7,8-dihydroxyflavone (DHF) (5 mg/kg body weight), a TrkB receptor agonist. We examined its potential protective effects on retinal vessel obliteration and neovascularization, two hallmarks of ROP and OIR. We found that retinas from DHF treated postnatal day 8 (P8) and P12 mice have similar levels of vessel obliteration as retinas from age-matched control mice subjected to OIR. Similarly, DHF showed no significant effect on mitigation of retinal neovascularization during OIR in P17 mice. Collectively, our studies demonstrate that the TrkB receptor agonist DHF provides no significant protective effects during OIR.

Description and management of retinopathy of prematurity reactivation after intravitreal antivascular endothelial growth factor therapy.

PURPOSE OF REVIEW: To review the literature regarding reactivation of retinopathy of prematurity (ROP) after treatment with antivascular endothelial growth factor (anti-VEGF) agents. RECENT FINDINGS: Reactivation can occur after anti-VEGF or laser. Risk factors for reactivation include patient and disease-related factors. Various studies are evaluating the use of different anti-VEGF agents and reactivation rates. However, the definition of reactivation varies between studies. SUMMARY: The literature has varied definitions of reactivation, which is often used interchangeably with recurrence. It is important to recognize features of reactivation of ROP to appropriately manage patients and conduct clinical trials. The International Classification of ROP 3rd edition has established a consensus guideline regarding terminology describing reactivation.

VEGF-mediated angiogenesis in retinopathy of prematurity is co-regulated by miR-17-5p and miR-20a-5p.

The microRNAs miR-17-5p and miR-20a-5p play important roles on angiogenesis; however, it is arguable whether they regulate the formation of retinal blood vessels in retinopathy of prematurity (ROP). We used a mouse model of oxygen-induced retinopathy (OIR) to simulate the development of retinas in mice suffering from ROP, and the expression levels of miR-20a-5p, miR-17-5p, hypoxia-inducible factor 1-alpha (HIF-1α), and vascular endothelial growth factor (VEGF) were measured by RT-qPCR and Western blotting. Cell proliferation, apoptosis, and angiogenesis in the OIR model mice were measured using MTT assays, flow cytometry, and Matrigel assays, respectively. The interaction between HIF-1α/VEGF and miR-20a-5p/miR-17-5p were further validated using dual-luciferase reporter assays, biotin-labeled RNA-pulldown, and RNA immunoprecipitation (RIP) assays. In our OIR model, retinal angiogenesis in the mice was associated with down-regulation of miR-20a-5p and miR-17-5p, as well as up-regulation of HIF-1α and VEGF. In addition, the miR-20a-5p and miR-17-5p inhibited cell proliferation and angiogenesis through regulating HIF-1α and VEGF in the retinal cells of the OIR model mice. Moreover, it was found that miR-20a-5p and miR-17-5p bind to HIF-1α and VEGF at the 3'UTR, and there was a combined effect between miR-20a-5p and miR-17-5p on the regulation of HIF-1α and VEGF. It is worth noting that miR-17-5p and miR-20a-5p can preferentially regulate HIF-1α, then act on VEGF, thereby affecting the angiogenesis associated with ROP.

MicroRNA-126 inhibits pathological retinal neovascularization via suppressing vascular endothelial growth factor expression in a rat model of retinopathy of prematurity.

Vascular endothelial growth factor (VEGF) is the principal growth factor responsible for the retinal neovascularization in the pathogenesis of retinopathy of prematurity (ROP). Current therapies for ROP include laser ablation and intravitreal anti-VEGF injection. However, these treatments either destroy the peripheral retina or associate with problems of persistent peripheral avascular retina or later recurrence of ROP. In the present study we investigated a new therapeutic approach by exploring the potential role of a specific microRNA, miR-126, in regulating VEGFA expression and retinal neovascularization in a rat oxygen-induced retinopathy (OIR) model. We demonstrated that miR-126 mimic and plasmid effectively suppresses VEGFA mRNA expression in both human and rat retinal pigment epithelium cell lines, quantified with qRT-PCR. Animal experiments on rat OIR model revealed that intravitreal injection of miR-126 plasmid efficiently downregulated VEGFA expression in the intraocular fluid and retinal tissues measured by ELISA, and significantly suppressed retinal neovascularization, which was confirmed by calculating sizes of neovascularization areas on fluorescence microscopic images of flat mounted retina stained with Alexa Fluor 594-conjugated isolectin B4 to visualize blood vessels. Together, these results showed that intravitreal injection of miR-126 plasmid could inhibit retinal neovascularization by down-regulating VEGFA expression, suggesting a potential therapeutic effect for ROP.

The Nrf2 inhibitor brusatol has a protective role in a rat model of oxygen-induced retinopathy of prematurity.

Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been testified to be involved in the development of retinopathy of prematurity (ROP), which can cause childhood visual impairment. Whether brusatol, an Nrf2 inhibitor, could be utilized to treat ROP was unknown. The oxygen-induced retinopathy rat model was established to mimic ROP, which was further intravitreal administrated with brusatol. Vessel morphology and microglial activation in the retina were assessed with histology analysis. The relative expression levels of angiogenesis and inflammation-related molecules were detected with Western blot and real-time polymerase chain reaction methods. Intravitreal brusatol administration could alleviate both angiogenesis and microgliosis induced by hyperoxia, along with down-regulation of vascular endothelial growth factor, vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, cluster of differentiation molecule 11B, tumor necrosis factor alpha, inducible nitric oxide synthase, glial fibrillary acidic protein, and IBA-1 expression. It was further revealed that Nrf2 and heme oxygenease-1 were diminished by brusatol administration. The results demonstrate the potential of intravitreal brusatol deliver to treat ROP with down-regulation of angiogenesis and microgliosis.

Ocular Versus Oral Propranolol for Prevention and/or Treatment of Oxygen-Induced Retinopathy in a Rat Model.

Purpose: Propranolol, a nonselective B1/B2 adrenoceptor antagonist, promotes the regression of infantile hemangiomas likely through suppression of vascular endothelial growth factor (VEGF), which prompted its use for the prevention of retinopathy of prematurity. We tested the hypothesis that topical ocular propranolol is safe and effective for reducing the severity of oxygen-induced retinopathy (OIR) in the neonatal rat intermittent hypoxia (IH) model. Methods: At birth (P0), rat pups were randomly assigned to room air or neonatal intermittent hypoxia (IH) consisting of 50% O2 with brief episodes of hypoxia (12% O2) from P0 to P14, during which they received a single daily dose of oral propranolol (1 mg/kg/day in 50 µL in sterile normal saline) or topical ocular propranolol (0.2% in 10 µL in normal saline) from P5 to P14. Placebo-controlled littermates received 50 µL oral or 10 µL topical ocular sterile normal saline. Retinal vascular and astrocyte integrity; retinal histopathology and morphometry; and angiogenesis biomarkers were determined. Results: Topical ocular propranolol improved retinal vascular damage and preserved the astrocytic template, but did not completely prevent OIR. The beneficial effects of propranolol were associated with reduced ocular VEGF and increased endogenous soluble inhibitor, sVEGFR-1, when administered topically. Conclusions: Propranolol failed to completely prevent severe OIR, however, it prevented astrocyte degeneration resulting from neonatal IH-induced damage. We conclude that the mechanisms of propranolol's beneficial effects in neonatal IH may involve in part, astrocyte preservation.

Effect of Decorin and Bevacizumab on oxygen-induced retinopathy in rat models: A comparative study.

Purpose: The aims of this study were to evaluate the effects of decorin (DCN) in rat oxygen-induced retinopathy (OIR) model and to compare the results with those of bevacizumab. Methods: Twenty-eight newborn Sprague-Dawley rats were randomly divided into four groups. Group I (control): normoxia plus intraperitoneal (ip) normal saline (NS), Group II (sham): OIR plus ip NS, Group III (DCN): OIR plus ip 0.1 mg/kg DCN, and Group IV (bevacizumab): OIR plus ip 2.5 mg/kg bevacizumab. The OIR model was induced by cycling the oxygen concentration between 50% and 10% every 24 h for 14 days following their birth. In all groups, injections were administered on postnatal day (PD) 15. All animals were sacrificed and their right eyes were enucleated on PD 18. The nuclei of neovascular endothelial cells on the vitreal side of the inner limiting membrane were counted, and vascular endothelial growth factor (VEGF) and tumor necrosis factor-alpha (TNF)-α immunoreactivity were detected in histopathological and immunohistochemical examinations. One-way analysis of variance and post hoc Tukey tests were used for statistical analyses of the data. Results: In Groups II, III, and IV, the mean neovascular cell nuclei counts were 13.14 ± 1.34, 6.57 ± 1.51, and 6.71 ± 1.49, respectively. The mean neovascular cell nuclei count was significantly reduced in treatment groups compared with sham group (P < 0.001). In immunohistochemical staining, the immunoreactivity of VEGF was 0.07 ± 0.02, 0.97 ± 0.21, 0.37 ± 0.12, and 0.23 ± 0.17, respectively. Likewise, immunoreactivity of TNF-α was 0.02 ± 0.02, 1.11 ± 0.36, 0.37 ± 0.13, and 0.62 ± 0.21, respectively. VEGF and TNF-α immunoreactivity increased markedly in the sham group compared with those in the control group (P < 0.001). VEGF and TNF-α immunoreactivity of treatment groups decreased significantly compared to sham group (P < 0.001). Conclusion: The beneficial effects obtained by DCN administration in OIR model were comparable to the effects of bevacizumab.

Efficacy of Aflibercept Treatment and Its Effect on the Retinal Perfusion in the Oxygen-Induced Retinopathy Mouse Model of Retinopathy of Prematurity.

INTRODUCTION: Bevacizumab and ranibizumab, which are anti-vascular endothelial growth factor (VEGF) medications, are used frequently in the treatment for retinopathy of prematurity (ROP) in infants. Aflibercept, or VEGF Trap, has been used anecdotally, but translation and clinical studies are lacking. OBJECTIVE: This study investigates the efficacy of aflibercept at reducing areas of non-perfused retina and studies its effect on normal angiogenesis in the oxygen-induced retinopathy mouse model of ROP. METHODS: C57BL/6 J mice were assigned to room air control (n = 21 eyes) or hyperoxia with 75% oxygen (n = 84 eyes). The hyperoxic mice were assigned to 1 of 3 groups: 0 ng (n = 14 eyes), 100 ng (n = 35 eyes), or 1,000 ng (n = 35 eyes) of intravitreal aflibercept administered on postnatal day 14. Eyes were enucleated at PN17 and PN25 postinjection. Retinas were stained with anti-collagen IV antibody and photographed with microscopy. Areas of perfused and non-perfused retina were quantified using ImageJ software. Statistical comparisons were made using ANOVA with Tukey post hoc comparisons. RESULTS: At PN17, there was no significant difference in the area of non-perfused retina between the hyperoxic control and the 100 and 1,000 ng aflibercept groups. At PN25, the 100 ng (p < 0.05) and 1,000 ng (p = 0.008) treatment groups displayed less non-perfusion compared to hyperoxic controls. At the 1,000 ng dose, there was increased non-perfusion compared to the 100 ng dose (p = 0.02). There was reduced non-perfusion by PN25 compared to PN17 for the 100 ng group (p < 0.05), with no difference in the 1,000 ng group. CONCLUSIONS: The study shows that the area of non-perfused retina decreases effectively with aflibercept at PN25 with 100 ng dosage. With the 1,000 ng dosage, there is an inhibition of the physiologic angiogenesis with a higher area of non-perfused retina.

Protective effects of rapamycin on the retinal vascular bed during the vaso-obliteration phase in mouse oxygen-induced retinopathy model.

Retinopathy of prematurity (ROP) is a vision-threatening disorder characterized with retinal vaso-obliteration in phase 1 and pathological neovascularization (NV) in phase 2. However, there has been no effective and safe treatment for ROP. Current management is mainly focused on the reduction of abnormal NV in phase 2, and anti-vascular endothelial growth factor (VEGF) therapy is the first-line treatment, yet, with great risks of late recurrence and systemic side effects. It has been reported that the severity of vaso-obliteration in phase 1 largely influences subsequent NV, suggesting that it may be a promising target to develop novel treatments for ROP. Here, we investigated the therapeutic potential and safety of early rapamycin intervention in treating phase 1 ROP and possible underlying mechanisms using the mouse model of oxygen-induced retinopathy (OIR). We found that intravitreal injection of rapamycin at postnatal day 7 (P7) significantly reduced retinal avascular area, increased vascular density, and reversed the suppression of deep capillaries development in phase 1 of OIR mice. Rapamycin treatment not only reduced vascular apoptosis, but also promoted proliferation and tip cell functions. Additionally, rapamycin did not interfere with normal retinal vascular development. Further investigation showed that Ang1/Tie2 pathway might be involved in rapamycin's vascular protection in phase 1 OIR retinas. Moreover, early rapamycin treatment at P7 had long-term protective effects of reducing retinal NV and avascular area, as well as enhancing vascular maturity in phase 2 of OIR mice. Together, our data suggest that rapamycin may be a safe and promising strategy for early intervention of ROP.

Small RNA Sequencing Reveals Transfer RNA-derived Small RNA Expression Profiles in Retinal Neovascularization.

Retinal neovascularization (RNV) is characterized in retinopathy of prematurity (ROP), diabetic retinopathy (DR), and retinal vein occlusion (RVO), which leads to severe vision loss and even blindness. To reveal the altered transfer RNA-derived small RNA (tsRNA)s in RNV, and to investigate the underlying mechanisms of the altered tsRNAs involved in RNV, we carried out a small RNA sequencing to profile tsRNA expressions in the retinas of mice with oxygen-induced retinopathy (OIR) and control mice. A total of 45 tsRNAs were significantly changed (fold change ≥ 1.5 and P < 0.05) in the retinas of OIR mice compared with controls. Validation by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) in four selected tsRNAs was consistent with the results of small RNA sequencing. Bioinformatics analyses identified 153 altered target genes of the four validated tsRNAs. These altered target genes were largely enriched in developmental process, cell periphery and protein binding, as well as Th1 and Th2 cell differentiation pathway. Our study suggests tsRNAs play key roles in the pathogenesis of RNV, indicating their therapeutic potential to treat patients with RNV. Moreover, small RNA sequencing is a useful tool to identify changes in tsRNA expression, an important indicator of the progress of retinal diseases.

Clinical impact of hydroxychloroquine dose adjustment according to the American Academy of Ophthalmology guidelines in systemic lupus erythematosus.

OBJECTIVE: The American Academy of Ophthalmology recommends a maximum hydroxychloroquine (HCQ) dose of ≤5.0 mg/kg/day to reduce the risk of HCQ-induced retinopathy. To determine if this dose adjustment would have an impact on the clinical course of SLE, we compared outcome measures in a cohort of patients with SLE before and after adjusting HCQ dose. METHODS: Sixty Puerto Ricans with SLE (per 1997 American College of Rheumatology criteria) treated with HCQ who were changed to HCQ ≤5.0 mg/kg/day were studied. Visits were ascertained every 6 months for 2 years before and 2 years after HCQ dose adjustment (baseline visit). Disease activity (per Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)), SLE exacerbations, emergency room visits, hospitalisations, disease damage (per Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index), corticosteroids exposure, prednisone dose and immunosuppressive drugs exposure were determined before and after HCQ dose change. RESULTS: At baseline visit, the mean age was 43.8±15.1 years. All patients were women. The mean disease duration was 13.8±9.1 years. After HCQ dose adjustment, patients required a lower prednisone dose when compared with visits before HCQ dose reduction. No significant differences were observed for mean SLEDAI scores, lupus exacerbations, emergency room visits, hospitalisations, disease damage and exposure to immunosuppressive drugs before and after HCQ dose adjustment. CONCLUSIONS: This study suggests that adjustment of daily HCQ dose to ≤5.0 mg/kg/day of actual body weight does not have a significant impact on the short-term and mid-term outcomes in this group of patients with SLE.