Prethreshold retinopathy of prematurity: VEGF inhibition without VEGF inhibitors

Association of low hemoglobin at birth and neurodevelopmental outcomes in preterm neonates ≤28 weeks' gestation: a retrospective cohort study

OBJECTIVE

To compare neurodevelopmental outcomes at 18-24 months corrected age (CA) for preterm infants who had hemoglobin levels <120 g/l versus those with hemoglobin level ≥120 g/l at birth.

METHODS

We included infants of ≤28 weeks gestational age (GA) born between January 2009 and June 2018. The primary outcome was neurodevelopmental impairment (NDI) at 18-24 months. Multivariable logistic regression was applied to determine the association.

RESULTS

Of the 2351 eligible neonates, 351 (14.9%) had hemoglobin levels <120 g/L at birth. Of the 2113 surviving infants, 1534 (72.5%) underwent developmental follow-up at 18-24 months CA. There was no statistically significant difference in ND outcomes between the two groups. The composite outcome of death or NDI was significantly higher in the low hemoglobin group.

CONCLUSION

In preterm infants ≤28 weeks GA, initial hemoglobin <120 g/L at birth was not associated with neurodevelopmental impairment at 18-24 months CA among survivors.

Pathophysiology of Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a complex disease involving development of the neural retina, ocular circulations, and other organ systems of the premature infant. The external stresses of the ex utero environment also influence the pathophysiology of ROP through interactions among retinal neural, vascular, and glial cells. There is variability among individual infants and presentations of the disease throughout the world, making ROP challenging to study. The methods used include representative animal models, cell culture, and clinical studies. This article describes the impact of maternal-fetal interactions; stresses that the preterm infant experiences; and biologic pathways of interest, including growth factor effects and cell-cell interactions, on the complex pathophysiology of ROP phenotypes in developed and emerging countries.

Strategies to Prevent Severe Retinopathy of Prematurity: A 2020 Update and Meta-analysis

The incidence of retinopathy of prematurity (ROP) is showing an increasing trend in the United States. This may be because of increasing survival rates among extremely preterm infants (<25 weeks' gestation) and targeting higher oxygen saturation. Five randomized clinical trials of low versus high oxygen saturation target ranges found increased mortality in the low oxygen saturation target group and an increased incidence of ROP in the high oxygen saturation target group. The American Academy of Pediatrics recommends using an oxygen saturation target range of 90% to 95% in extremely low-birthweight infants. The change of practice to target this higher oxygen saturation range, from admission until discharge, may be contributing to the increasing incidence of ROP in extremely preterm infants. To decrease the incidence of ROP without increasing mortality, 2 new cohort trials suggest gradually increasing oxygen saturation targets as preterm infants mature. There is evidence that human milk, vitamin A, and omega-3 fatty acids can help, in addition to continuous oxygen saturation monitoring, to decrease the risk of ROP. We review this literature and provide a meta-analysis to evaluate the evidence.

The Serine Protease HTRA-1 Is a Biomarker for ROP and Mediates Retinal Neovascularization

Retinopathy of prematurity (ROP) is a blinding aberrancy of retinal vascular maturation in preterm infants. Despite delayed onset after preterm birth, representing a window for therapeutic intervention, we cannot prevent or cure ROP blindness. A natural form of ROP protection exists in the setting of early-onset maternal preeclampsia, though is not well characterized. As ischemia is a central feature in both ROP and preeclampsia, we hypothesized that angiogenesis mediators may underlie this protection. To test our hypothesis we analyzed peripheral blood expression of candidate proteins with suggested roles in preeclamptic and ROP pathophysiology and with a proposed angiogenesis function (HTRA-1, IGF-1, TGFβ-1, and VEGF-A). Analysis in a discovery cohort of 40 maternal-infant pairs found that elevated HTRA-1 (high-temperature requirement-A serine peptidase-1) was significantly associated with increased risk of ROP and the absence of preeclampsia, thus fitting a model of preeclampsia-mediated ROP protection. We validated these findings and further demonstrated a dose-response between systemic infant HTRA-1 expression and risk for ROP development in a larger and more diverse validation cohort consisting of preterm infants recruited from two institutions. Functional analysis in the oxygen-induced retinopathy (OIR) murine model of ROP supported our systemic human findings at the local tissue level, demonstrating that HtrA-1 expression is elevated in both the neurosensory retina and retinal pigment epithelium by RT-PCR in the ROP disease state. Finally, transgenic mice over-expressing HtrA-1 demonstrate greater ROP disease severity in this model. Thus, HTRA-1 may underlie ROP protection in preeclampsia and represent an avenue for disease prevention, which does not currently exist.