Translational Research in Retinopathy of Prematurity: From Bedside to Bench and Back Again

Characteristics of retinal vascularization in reactivated retinopathy of prematurity requiring treatment and clinical outcome after reinjection of ranibizumab

This study aimed to determine whether the state of retinal vascularization after anti-vascular endothelial growth factor (anti-VEGF) injection can help predict the risk of reactivated retinopathy of prematurity (ROP) requiring treatment and whether repeated ranibizumab injection will be effective in such cases. We retrospectively reviewed 24 infants (43 eyes) who received ranibizumab monotherapy between January 2021 and December 2022. All eyes were classified as having non-retreated ROP or retreated ROP. The state of ROP at the time of treatment, the time required for resolution of plus disease, and the extent of vascularization at 4 and 8 weeks after treatment were analyzed. Extent of temporal retinal vascularization was measured with serial fundus images using disc-fovea distance (DF) unit and disc diameter (DD). Reactivated ROP requiring treatment occurred in six infants (25.0%) and ten eyes (23.3%) after ranibizumab treatment. The mean retreatment interval was 9.0 ± 3.3 weeks (range 4-16). In the retreated ROP group, the time required for the resolution of plus disease after primary injection was longer compared to the control group (13.3 days vs 5.2 days), with a mean ROP regression time of 3.4 weeks. All eyes in the retreated ROP showed retinal vascularization < 0.5 DF from the original site at 4 weeks after injection. In 90% of cases with retreated ROP, the extent of vascularization at 8 weeks after injection was within 1 DF from the original ROP site, and all cases showed reactivation in the posterior Zone II area. The extent of retinal neovascularization in the retreated group was an average of 0.7 DD (vs 1.7 DD) and 1.3 DD (vs 3.3 DD) at 4 and 8 weeks after injection, respectively. After ranibizumab retreatment, only one reactivated case with vitreous traction progressed to focal retinal detachment, while all other cases regressed with peripheral vascular development. The continuation of delayed retinal blood vessel development after ≥ 8 weeks may indicate a high likelihood of reactivated ROP requiring treatment. In the absence of vitreous traction, ranibizumab reinjection is likely to be effective in treating reactivated ROP requiring treatment.

Critical period of oxygen supplementation and invasive ventilation: implications for severe retinopathy of prematurity

BACKGROUND

Several studies have identified graded oxygen saturation targets to prevent retinopathy of prematurity (ROP), a serious complication in preterm infants. We aimed to analyze the critical period of oxygen supplementation and/or invasive ventilation associated with severe ROP.

METHODS

This retrospective case-control study included neonates with a gestational age (GA) < 29 weeks. Participants were divided into two groups: treated retinopathy and untreated/no retinopathy. Time-weighted average FiO2 (TWAFiO2) and weekly invasive ventilation were compared between groups by postnatal age (PNA) and postmenstrual age (PMA). The association of treated retinopathy with TWAFiO2 and invasive ventilation was analyzed.

RESULTS

Data from 287 neonates were analyzed; 98 were treated for ROP and had lower GAs (25.5 vs. 27.4 weeks, p < 0.01) and lower birthweights (747.6 vs. 1014 g, p < 0.001) than those with untreated/no ROP. TWAFiO2 was higher from PMA 26-34 weeks, except for PMA 31 weeks in treated ROP, and higher in the first nine weeks of life in treated ROP. On multiple logistic regression, TWAFiO2 and invasive ventilation were associated with ROP treatment during the first seven weeks PNA. Invasive ventilation was associated with ROP treatment from PMA 26-31 weeks; no association was found for TWAFiO2 and PMA.

CONCLUSIONS

Amount of oxygen supplementation and/or invasive ventilation during the first 7 weeks of life or up to 31 weeks PMA was associated with development of severe ROP. This period might be candidate timing for strict oxygen supplementation strategies in preterm infants, while concerns of mortality with low oxygen supplementation should be further explored.

Latest Trends in Retinopathy of Prematurity: Research on Risk Factors, Diagnostic Methods and Therapies

Retinopathy of prematurity (ROP) is a vasoproliferative disorder with an imminent risk of blindness, in cases where early diagnosis and treatment are not performed. The doctors' constant motivation to give these fragile beings a chance at life with optimal visual acuity has never stopped, since Terry first described this condition. Thus, throughout time, several specific advancements have been made in the management of ROP. Apart from the most known risk factors, this narrative review brings to light the latest research about new potential risk factors, such as: proteinuria, insulin-like growth factor 1 (IGF-1) and blood transfusions. Digital imaging has revolutionized the management of retinal pathologies, and it is more and more used in identifying and staging ROP, particularly in the disadvantaged regions by the means of telescreening. Moreover, optical coherence tomography (OCT) and automated diagnostic tools based on deep learning offer new perspectives on the ROP diagnosis. The new therapeutical trend based on the use of anti-VEGF agents is increasingly used in the treatment of ROP patients, and recent research sustains the theory according to which these agents do not interfere with the neurodevelopment of premature babies.

Modulation of cGAS-STING signaling by PPARα in a mouse model of ischemia-induced retinopathy

In ischemic retinopathy, overactivated retinal myeloid cells are a crucial driving force of pathological angiogenesis and inflammation. The cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) signaling are key regulators of inflammation. This study aims to investigate the association of cGAS-STING signaling with ischemic retinopathy and the regulation of its activation. We found that protein levels of cGAS and STING were markedly up-regulated in retinal myeloid cells isolated from mice with oxygen-induced retinopathy (OIR). Knockout of Sting and pharmacological inhibition of STING both alleviated retinal neovascularization (NV) and reduced retinal vascular leakage in OIR. Further, Sting knockout and STING inhibitor also alleviated leukocyte adhesion to retinal vasculature and infiltration into the retina as well as microglial activation in OIR. These results suggest that cGAS-STING signaling played a pathogenic role in retinal myeloid cell activation and NV in ischemic retinopathy. To identify the regulation of cGAS-STING signaling in OIR, we evaluated the role of transcription factor peroxisome proliferator-activated receptor α (PPARα). The results demonstrated that PPARα was down-regulated in OIR retinas, primarily in myeloid cells. Furthermore, Pparα knockout significantly up-regulated cGAS and STING levels in retinal CD11b+ cells, while PPARα agonist inhibited cGAS-STING signaling and cytosolic mitochondrial DNA (mtDNA) release, a causative feature for cGAS activation. Knockout of Sting ameliorated retinal NV, hyperpermeability, and leukostasis in Pparα-/- mice with OIR. These observations suggest that PPARα regulates cGAS-STING signaling, likely through mtDNA release, and thus, is a potential therapeutic target for ischemic retinopathy.

New insights in pediatrics in 2021: choices in allergy and immunology, critical care, endocrinology, gastroenterology, genetics, haematology, infectious diseases, neonatology, neurology, nutrition, palliative care, respiratory tract illnesses and telemedicine

In this review, we report the developments across pediatric subspecialties that have been published in the Italian Journal of Pediatrics in 2021. We highlight advances in allergy and immunology, critical care, endocrinology, gastroenterology, genetics, hematology, infectious diseases, neonatology, neurology, nutrition, palliative care, respiratory tract illnesses and telemedicine.

Targeting proliferative retinopathy: Arginase 1 limits vitreoretinal neovascularization and promotes angiogenic repair

Current therapies for treatment of proliferative retinopathy focus on retinal neovascularization (RNV) during advanced disease and can trigger adverse side-effects. Here, we have tested a new strategy for limiting neurovascular injury and promoting repair during early-stage disease. We have recently shown that treatment with a stable, pegylated drug form of the ureohydrolase enzyme arginase 1 (A1) provides neuroprotection in acute models of ischemia/reperfusion injury, optic nerve crush, and ischemic stroke. Now, we have determined the effects of this treatment on RNV, vascular repair, and retinal function in the mouse oxygen-induced retinopathy (OIR) model of retinopathy of prematurity (ROP). Our studies in the OIR model show that treatment with pegylated A1 (PEG-A1), inhibits pathological RNV, promotes angiogenic repair, and improves retinal function by a mechanism involving decreased expression of TNF, iNOS, and VEGF and increased expression of FGF2 and A1. We further show that A1 is expressed in myeloid cells and areas of RNV in retinal sections from mice with OIR and human diabetic retinopathy (DR) patients and in blood samples from ROP patients. Moreover, studies using knockout mice with hemizygous deletion of A1 show worsened RNV and retinal injury, supporting the protective role of A1 in limiting the OIR-induced pathology. Collectively, A1 is critically involved in reparative angiogenesis and neuroprotection in OIR. Pegylated A1 may offer a novel therapy for limiting retinal injury and promoting repair during proliferative retinopathy.

Early and late onset sepsis and retinopathy of prematurity in a cohort of preterm infants

This study investigates the impact of antenatal and postnatal infection or inflammation on the onset and progression of Retinopathy of Prematurity (ROP). We retrospectively collected clinical and demographic data of preterm infants with birth weight ≤ 1500 g or gestational age < 30 weeks admitted to the neonatal intensive care unit of Verona from 2015 to 2019. Uni- and multivariable analysis was performed to evaluate the potential effect of selected variables on the occurrence of any stage ROP and its progression to severe ROP, defined as ROP requiring treatment. Two hundred and eighty neonates were enrolled and 60 of them developed ROP (21.4%). Oxygen need for 28 days and late-onset sepsis (LOS) increased the risk of any grade ROP after adjusting for birth weight and gestational age (OR 6.35, 95% CI 2.14–18.85 and OR 2.49, 95% CI 1.04–5.94, respectively). Days of mechanical ventilation and of non-invasive ventilation increased the risk of progression to severe ROP after adjusting for birth weight and gestational age (OR 1.08, CI 1.02–1.14 and OR 1.06, CI 1.01–1.11, respectively). Exposure to infection with production of inflammatory mediators may contribute to increase the risk of ROP occurrence in very preterm neonates.