Low IGF-I suppresses VEGF-survival signaling in retinal endothelial cells: direct correlation with clinical retinopathy of prematurity

New advances in pharmacological research for retinopathy of prematurity

Retinopathy of prematurity (ROP) is a proliferative retinal vascular disease that threatens the vision of premature infants. Various novel drugs have demonstrated therapeutic potential for ROP by targeting signaling pathways associated with vascular endothelial growth factor (VEGF), including PI3K/AKT, hypoxia-inducible factor (HIF)-1α/VEGF, oxidative stress, tumor necrosis factor (TNF)-α, and Notch pathways. Propranolol, insulin-like growth factor-1, and celecoxib attenuate pathological neovascularization via the PI3K/AKT signaling pathway. Tripterine and melatonin inhibit retinal neovascularization by modulating the HIF-1α/VEGF signaling axis. Adiponectin mitigates oxidative stress damage and preserves endothelial function by enhancing endothelial nitric oxide synthase activity. Omega-3 polyunsaturated fatty acids suppress TNF-α-mediated inflammatory responses, modulate retinal development and angiogenesis, and reduce retinal neovascular lesions. The γ-secretase inhibitor DAPT blocks Notch signaling to suppress abnormal vascular proliferation. These agents exhibit synergistic multi-pathway anti-angiogenic effects in preclinical models and early-phase clinical trials, offering critical insights for advancing drug development and clinical translation in ROP management.

Retinopathy of Prematurity (ROP): An Overview of Biomarkers in Various Samples for Prediction, Diagnosis, and Prognosis

Retinopathy of Prematurity (ROP) is a proliferative retinal vascular disease marked by abnormal development of retinal vessels in low birth weight preterm infants. It is one of the leading causes of blindness in preterm infants. Current ROP screening methods impose high demands on both the equipment and the expertise of ophthalmologists, which limits their widespread application, particularly in secondary hospitals and remote areas. Thus, the identification of relevant biomarkers and the development of simpler detection methods are important and promising. Non-invasive or minimally invasive sampling methods, along with biomarkers possessing high sensitivity and specificity, could greatly enhance neonatal screening, facilitate early diagnosis, and improve prevention of blindness in preterm infants. This review provides relevant medical insights for clinical practice. This review explored, compares and analyzes various sampling sources. It compares and analyzes research on ROP-related biomarkers derived from these samples.

Prolonged Parenteral Nutrition Increases the Risk of Comorbidities in Very-Low-Birth-Weight Infants: A Prospective National Cohort Study in South Korea

Background/Objectives: There has been an increase in the incidence of comorbidities among very-low-birth-weight infants (VLBWIs), including periventricular leukomalacia (PVL), bronchopulmonary dysplasia (BPD), and retinopathy of prematurity (ROP). Parenteral nutrition is essential for very-low-birth-weight infants (VLBWIs) who are born with a birth weight of less than 1500 g, but a longer duration of parenteral nutrition is known to have a risk of comorbidity, such as ROP. This study aims to investigate the relationship between the duration of parenteral nutrition and the comorbidities of the VLBWIs. Methods: Using the prospective cohort of Korean neonatal network, we analyzed the perinatal and postnatal data before discharge of the total 2490 subjects born in 2021 and 2022. The primary outcomes were the diagnoses of PVL, BPD, and ROP. The secondary outcomes were the severity of BPD and ROP, treatment of ROP, and proposing the predictive model of comorbidities using the duration of parenteral nutrition. Results: This study found that prolonged parenteral nutrition exceeding 28 days was associated with a higher risk of PVL (odds ratio [OR] 1.71, 95% confidence interval [CI] [1.11, 2.64], p = 0.002) and BPD (OR 1.51, 95% CI [1.10, 2.08], p = 0.011). Furthermore, an intermediate duration of parenteral nutrition was found to be significantly associated with an increased risk of ROP in male subjects. Additionally, a prolonged duration of parenteral nutrition was observed to be linked to greater severity of BPD. Predictive models incorporating the duration of parenteral nutrition demonstrated a high degree of explanatory power in relation to both BPD and ROP. Conclusions: Longer duration of parenteral nutrition has a risk of critical comorbidities in VLBWIs. The nutrition strategy for shorter parenteral nutrition should be encouraged for the prevention of comorbidities.

Early-Onset Sepsis as an Early Predictor for Retinopathy of Prematurity: A Meta-analysis

OBJECTIVE

 Neonatal sepsis has been established as a risk factor for retinopathy of prematurity (ROP) but previous meta-analyses have predominately focused on late-onset sepsis (LOS). This meta-analysis aims to explore the association between early-onset sepsis (EOS) and the risk of ROP.

STUDY DESIGN

 Observational studies reporting (unadjusted) data on proven EOS in neonates with ROP were included. PubMed, Embase, and Cochrane Library were searched. Proven EOS was defined as a positive blood or cerebrospinal fluid culture. Effect sizes were calculated by using logistic random-effects models and meta-regression analyses. Primary outcomes were any stage ROP and severe ROP (≥stage 3, type I, aggressive [posterior] ROP, plus disease or requiring treatment). Potential confounders explored were gestational age at birth, birth weight, small for gestational age, maternal steroid use, necrotizing enterocolitis, LOS, and mechanical ventilation duration.

RESULTS

 Seventeen studies reporting the incidence of proven EOS in neonates with ROP were included. Proven EOS showed no significant association with any stage ROP (odds ratio [OR] = 1.90; 95% confidence interval [CI]: 0.96-3.79, p = 0.067) but heterogeneity between studies was significantly high. Neonates with proven EOS had an increased risk for severe ROP (OR = 2.21; 95% CI: 1.68-2.90), and no significant confounders influencing this effect size were found in the meta-regression analysis.

CONCLUSION

 Neonates with proven EOS are at increased risk of severe ROP. Neonatologists need to be aware that EOS is an early predictor of ROP and should adapt their policy and treatment decisions where possible to reduce ROP.

KEY POINTS

· This meta-analysis reveals a 2.2-fold increased risk of severe ROP in neonates with proven EOS.. · Future studies should distinguish between EOS and LOS when investigating risk factors of ROP.. · Treatment decisions should be adapted where possible in neonates with EOS before ROP screening begins..

Application of WINROP to predict severe retinopathy of prematurity in a multi-ethnic cohort in Singapore

AIM

To investigate the validity of WINROP use in multi-ethnic population in a tertiary centre in Singapore.

METHODS

Birth weight, gestational age, and weekly weight measurements of four hundred two preterm infants (<32 weeks gestation) born between year 2011 and 2019 were entered into WINROP algorithm. Based on their weekly weight gain, WINROP algorithm would signal an alarm if the infant is at risk for type 1 ROP requiring treatment. The WINROP result is then compared with the ophthalmological findings. All the infants were screened based on the hospital ROP screening protocol. The negative predictive value, positive predictive value, sensitivity and specificity were calculated.

RESULTS

Among all the infants enrolled, 31 infants developed type 1 ROP. WINROP successfully signalled 23 out of 31 correctly. The calculated sensitivity was 74.2 % and specificity was 48.0 %. The positive predictive value was 10.6% and negative predictive value was 95.7%.

CONCLUSIONS

Our study showed that when WINROP is applied to our multi-ethnic population, it has a moderate sensitivity of 74.2% and a high predictive negative value of 95.7%. We would not recommend it to be used a solitary screening method but it can be used to better risk stratify preterm infants at risk of type 1 ROP, particularly in resource limited settings.

Cytokine and growth factor correlation networks associated with morbidities in extremely preterm infants

BACKGROUND

Cytokines and growth factors (GF) have been implicated in the development of retinopathy of prematurity (ROP) and bronchopulmonary dysplasia (BPD). We hypothesize that even small coordinated changes in inflammatory proteins or GFs may reveal changes in underlying regulating mechanisms that do not induce obvious changes in concentration of individual proteins. We therefore applied correlation network analysis of serum factors to determine early characteristics of these conditions.

METHODS

Concentrations of 17 cytokines and five GFs were measured and analysed in blood samples from cord blood, on day one and during the following month in 72 extremely preterm infants. Spearman's correlation networks distinguishing BPD and severe ROP patients from non-affected were created.

RESULTS

Most cytokine concentrations correlated positively with each other and negatively with GFs. Very few individual cytokines differed between patients with and without ROP or BPD. However, networks of differently correlated serum factors were characteristic of the diseases and changed with time. In ROP networks, EPO, G-CSF and IL-8 (cord blood), BDNF and VEGF-A (first month) were prominent. In BPD networks, IL-1β, IGF-1 and IL-17 (day one) were noted.

CONCLUSIONS

Network analysis identifies protein signatures related to ROP or BPD in extremely preterm infants. The identified interactions between serum factors are not evident from the analysis of their individual levels, but may reveal underlying pathophysiological mechanisms in the development of these diseases.

Recurrence of Retinopathy of Prematurity Following Anti-vascular Endothelial Growth Factor (Anti-VEGF) Therapy: A Systematic Review and Meta-Analysis

Retinopathy of prematurity (ROP) is a neovascular disorder which affects premature infants and can lead to childhood blindness. Treatment includes laser photocoagulation and intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections, both effective options. However, laser photocoagulation can lead to refractive errors, while anti-VEGF therapy can result in disease recurrence. Our systematic review aimed to evaluate the recurrence rates of ROP following treatment with anti-VEGF agents compared to other anti-VEGF agents and laser photocoagulation. We also aimed to measure the retreatment intervals and assess successful retreatment rates to identify the most effective treatment modality. Our review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and included both randomized controlled trials (RCTs) and non-randomized comparative studies (NCS). A thorough search of MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL) databases was performed. Studies were assessed using the Cochrane Risk of Bias (RoB2) tool and the Newcastle-Ottawa Scale (NOS). Random-effects and fixed-effects models were used to measure pooled estimates. The outcomes were reported as risk ratios (RR) and standardized mean differences (SMD). A total of 21 studies (six RCTs and 15 NCS) with 6,152 eyes were included. Overall, anti-VEGF agents showed a higher risk of recurrence compared to laser photocoagulation (RR=2.14, 95% CI: 1.06-4.33, p=0.03). Conbercept demonstrated a significantly lower risk of recurrence than laser photocoagulation and ranibizumab (RR=0.47, 95% CI: 0.39-0.58, p<0.00001), while aflibercept showed a higher recurrence risk compared to bevacizumab (RR=12.61, 95% CI: 6.43-24.73, p<0.00001). Bevacizumab was associated with a longer retreatment interval than laser photocoagulation (SMD=0.89, 95% CI: 0.61-1.17, p<0.00001). No significant differences in retreatment success rates between bevacizumab and laser photocoagulation were observed. Anti-VEGF therapy is effective in the treatment of ROP; however, it is associated with a higher risk of recurrence compared to laser photocoagulation. Conbercept shows greater efficacy in reducing recurrence risk and prolonging the retreatment interval compared to ranibizumab. Aflibercept demonstrated inconsistent outcomes. No significant difference in recurrence rates was observed between bevacizumab and ranibizumab. Recurrences occurred significantly later when anti-VEGF therapy was used compared to laser photocoagulation. Successful retreatment rates between bevacizumab and laser photocoagulation were similar.

Heme: A link between hemorrhage and retinopathy of prematurity progression

Neovascularization is implicated in the pathology of retinopathy of prematurity (ROP), diabetic retinopathy (DR), and age-related macular degeneration (AMD), which are the leading causes of blindness worldwide. In our work, we analyzed how heme released during hemorrhage affects hypoxic response and neovascularization. Our retrospective clinical analysis demonstrated, that hemorrhage was associated with more severe retinal neovascularization in ROP patients. Our heme-stimulated human retinal pigment epithelial (ARPE-19) cell studies demonstrated increased expression of positive regulators of angiogenesis, including vascular endothelial growth factor-A (VEGFA), a key player of ROP, DR and AMD, and highlighted the activation of the PI3K/AKT/mTOR/VEGFA pathway involved in angiogenesis in response to heme. Furthermore, heme decreased oxidative phosphorylation in the mitochondria, augmented glycolysis, facilitated HIF-1α nuclear translocation, and increased VEGFA/GLUT1/PDK1 expression suggesting HIF-1α-driven hypoxic response in ARPE-19 cells without effecting the metabolism of reactive oxygen species. Inhibitors of HIF-1α, PI3K and suppression of mTOR pathway by clinically promising drug, rapamycin, mitigated heme-provoked cellular response. Our data proved that oxidatively modified forms of hemoglobin can be sources of heme to induce VEGFA during retinal hemorrhage. We propose that hemorrhage is involved in the pathology of ROP, DR, and AMD.

Placental Gene Therapy for Fetal Growth Restriction and Preeclampsia: Preclinical Studies and Prospects for Clinical Application

In the last three decades, gene therapy has demonstrated significant progress. Over 700 active investigational new drug (IND) applications have been reported. Research on in utero gene therapy has advanced, but ethical and safety concerns persist. A novel approach under investigation is placental gene therapy, which holds promise for targeting diseases associated with placental dysfunction, such as fetal growth restriction (FGR) and preeclampsia. One of the underlying causes of placental insufficiency in these conditions is reduced placental growth factor-driven angiogenesis and endothelial cell dysfunction during fetal development. Studies have explored the overexpression of growth factor transgenes like IGF-1 to address FGR, yielding promising outcomes in animal models. Furthermore, intra-placental gene transfer, instead of systemic delivery of gene therapy vectors, has the potential to treat and cure these disorders. However, challenges and limitations akin to in utero gene therapy persist, including the risk of in utero infection, potential impairment of the mother's future fertility, the risk of germline integration, and possible off-target effects of gene transfer in the fetus or the mother. Consequently, additional research and deliberation within the scientific and medical communities are warranted to fully comprehend the potential benefits and risks of placental gene therapy.

When IGF-1 Meets Metabolic Inflammation and Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder associated with insulin resistance (IR) and hyperandrogenaemia (HA). Metabolic inflammation (MI), characterized by a chronic low-grade inflammatory state, is intimately linked with chronic metabolic diseases such as IR and diabetes and is also considered an essential factor in the development of PCOS. Insulin-like growth factor 1 (IGF-1) plays an essential role in PCOS pathogenesis through its multiple functions in regulating cell proliferation metabolic processes and reducing inflammatory responses. This review summarizes the molecular mechanisms by which IGF-1, via MI, participates in the onset and progression of PCOS, aiming to provide insights for studies and clinical treatment of PCOS.

Tear fluid cytokine analysis: a non-invasive approach for assessing retinopathy of prematurity severity

PURPOSE

To determine whether there is a significant association between inflammatory cytokines in the tear fluid and the severity of Retinopathy of Prematurity (ROP).

STUDY DESIGN

Retrospective cohort study.

METHODS

The cytokine levels in tear fluids were determined in 34 eyes with ROP and 18 eyes without ROP. There were 15 eyes with severe ROP requiring treatment and 19 eyes with mild ROP not requiring treatment. For severe ROP eyes, tear fluids were collected before treatment.

RESULTS

Significantly higher levels of CCL2 and vascular endothelial growth factor (VEGF) were detected in eyes with severe ROP compared to eyes with mild ROP and no ROP. When assessed for cytokine levels that discriminate each disease group, CCL2 showed a significant odds ratio of 1.76 for severity change (/quintile, P = 0.032, after adjusting for birth weight). Correlation analysis showed that birth weight correlated with IL-1α levels, and decreased weight gain increased IFN-γ levels. We next determined tear fluid cytokines which discriminate severe ROP using receiver operating characteristics' analysis. We found that combination of higher CCL2 levels, higher VEGF levels, and lower IFN-γ levels in the tear fluid had a stronger predictive value for severe ROP (area under curve, 0.85).

CONCLUSION

The levels of CCL2, VEGF, and IFN-γ in tear fluid may serve as useful biomarkers for assessing the severity of ROP.

Histological Chorioamnionitis and Funisitis as New Risk Factors for Retinopathy of Prematurity: A Meta-analysis

OBJECTIVE

 The role of placental inflammation in neonatal morbidities is underestimated due to lack of placental examination. This meta-analysis aims to assess the association between histological chorioamnionitis (HCA) with and without funisitis (FUN) and risk of retinopathy of prematurity (ROP).

STUDY DESIGN

 Forty-five studies reporting (unadjusted) data on HCA without FUN and HCA with FUN in neonates with ROP were included. Primary outcomes were any stage ROP and severe ROP. Potential confounders explored were gestational age (GA) at birth, birthweight, maternal steroid use, necrotizing enterocolitis, sepsis (suspected/proven) and mechanical ventilation duration.

RESULTS

 Neonates with HCA had increased risk for any stage ROP (odds ratio [OR] 1.8; 95% confidence interval [CI] 1.3-2.4) and severe ROP (OR 1.5; 95% CI 1.2-1.8) compared with neonates without HCA. The rates of any stage ROP (OR 1.8; 95% CI 1.4-2.2) and severe ROP (OR 1.4; 95% CI 1.1-1.6) were higher in neonates with FUN compared with neonates without FUN. Multivariate meta-regression analysis suggests that lower GA increases the effect size between FUN and severe ROP.

CONCLUSION

 This meta-analysis confirms that presence of HCA and FUN are risk factors for any stage ROP and severe ROP. Structured histological placental examination of HCA and FUN may be a tool to further refine the ROP risk profile.

KEY POINTS

· This systematic review confirms that HCA is a risk factor for ROP.. · This meta-analysis reveals that FUN results in an even higher risk for developing ROP.. · Placental examination of HCA/FUN may be a tool to further refine the ROP risk profile..

Combination of blockade of endothelin signalling and compensation of IGF1 expression protects the retina from degeneration

Retinitis pigmentosa (RP) and macular dystrophy (MD) cause severe retinal dysfunction, affecting 1 in 4000 people worldwide. This disease is currently assumed to be intractable, because effective therapeutic methods have not been established, regardless of genetic or sporadic traits. Here, we examined a RP mouse model in which the Prominin-1 (Prom1) gene was deficient and investigated the molecular events occurring at the outset of retinal dysfunction. We extracted the Prom1-deficient retina subjected to light exposure for a short time, conducted single-cell expression profiling, and compared the gene expression with and without stimuli. We identified the cells and genes whose expression levels change directly in response to light stimuli. Among the genes altered by light stimulation, Igf1 was decreased in rod photoreceptor cells and astrocytes under the light-stimulated condition. Consistently, the insulin-like growth factor (IGF) signal was weakened in light-stimulated photoreceptor cells. The recovery of Igf1 expression with the adeno-associated virus (AAV) prevented photoreceptor cell death, and its treatment in combination with the endothelin receptor antagonist led to the blockade of abnormal glial activation and the promotion of glycolysis, thereby resulting in the improvement of retinal functions, as assayed by electroretinography. We additionally demonstrated that the attenuation of mammalian/mechanistic target of rapamycin (mTOR), which mediates IGF signalling, leads to complications in maintaining retinal homeostasis. Together, we propose that combinatorial manipulation of distinct mechanisms is useful for the maintenance of the retinal condition.

Validation of a Published Model to Reduce Burden of Retinopathy of Prematurity Screening

PURPOSE

The E-ROP study evaluated 1257 patients screened for retinopathy of prematurity (ROP), and found that no infant born at or after 27 weeks' gestational age and having a birthweight over 750 g developed treatable disease if they had no ROP at 37 weeks' gestational age. The study investigators suggested that there is little value in continued screening of infants meeting these criteria who have no ROP at 37 weeks. We attempted to replicate these published data in a larger multi-center cohort to validate or refute this hypothesis.

DESIGN

Retrospective cohort study.

METHODS

We conducted a chart review of every infant treated for ROP from February 2004 through April 2022 at 6 medical centers located in the mid-southern region of the United States. We evaluated gestational age, birthweight, and presence or absence of ROP at 37 weeks' gestational age to determine whether any treated infants would have been "missed" using these screening criteria.

RESULTS

Of 6729 infants screened, 298 (4.43%) received treatment. Ten infants who required treatment developed first evidence of ROP after 37 weeks' gestational age. However, only 1 infant was >750 g birthweight and >27 weeks' gestational age. This patient developed zone 2, stage 3 with pre-plus disease and was treated because of limited access to care at a remote hospital; however, ROP was detected at the first examination after 37 weeks, so this infant would have been identified for continued follow-up.

CONCLUSION

Our results, in a cohort 5 times that of the original study, replicated that infants >750 g birthweight and >27 weeks' gestational age did not develop treatable ROP if they had no ROP at 37 weeks, supporting the termination of examination at that time in patients meeting these criteria.

Insulin-like growth factor 1 associated with altered immune responses in preterm infants and pigs

BACKGROUND

Preterm infants show low blood levels of insulin-like growth factor 1 (IGF-1), known to be negatively correlated with Interleukin-6 (IL-6). We hypothesized that circulating IGF-1 is associated with systemic immune-markers following preterm birth and that exogenous IGF-1 supplementation modulates immune development in preterm pigs, used as model for preterm infants.

METHODS

Plasma levels of IGF-1 and 29 inflammatory markers were measured in very preterm infants (n = 221). In preterm pigs, systemic immune development, assessed by in vitro challenge, was compared between IGF-1 treated (2.25 mg/kg/day) and control animals.

RESULTS

Preterm infants with lowest gestational age and birth weight showed the lowest IGF-1 levels, which were correlated not only with IL-6, but a range of immune-markers. IGF-1 supplementation to preterm pigs reduced plasma IL-10 and Interferon-γ (IFN-γ), IL-2 responses to challenge and reduced expression of genes related to Th1 polarization. In vitro addition of IGF-1 (100 ng/mL) further reduced the IL-2 and IFN-γ responses but increased IL-10 response.

CONCLUSIONS

In preterm infants, plasma IGF-1 correlated with several immune markers, while supplementing IGF-1 to preterm pigs tended to reduce Th1 immune responses. Future studies should document whether IGF-1 supplementation to preterm infants affects immune development and sensitivity to infection.

IMPACT

Supplementation of insulin-like growth factor 1 (IGF-1) to preterm infants has been proposed to promote postnatal growth, but its impact on the developing immune system is largely unknown. In a cohort of very preterm infants, low gestational age and birth weight were the primary predictors of low plasma levels of IGF-1, which in turn were associated with plasma immune markers. Meanwhile, in immature preterm pigs, experimental supplementation of IGF-1 reduced Th1-related immune responses in early life. Supplementation of IGF-1 to preterm infants may affect the developing immune system, which needs consideration when evaluating overall impact on neonatal health.

Gut Microbiome and Retinopathy of Prematurity

Retinopathy of prematurity (ROP), a leading cause of childhood blindness worldwide, is strongly associated with gestational age and weight at birth. Yet, many extremely preterm infants never develop ROP or develop only mild ROP with spontaneous regression. In addition, a myriad of other factors play a role in the retinal pathology, one of which may include the early gut microbiome. The complications associated with early gestational age include dysbiosis of the dynamic neonatal gut microbiome, as evidenced by the development of often concomitant conditions, such as necrotizing enterocolitis. Given this, alongside growing evidence for a gut-retina axis, there is an increasing interest in how the early intestinal environment may play a role in the pathophysiology of ROP. Potential mechanisms include dysregulation of vascular endothelial growth factor and insulin-like growth factor 1. Furthermore, the gut microbiome may be impacted by other known risk factors for ROP, such as intermittent hypoxia and sepsis treated with antibiotics. This mini-review summarizes the literature supporting these proposed avenues, establishing a foundation to guide future studies.

Research hotspots and trends in retinopathy of prematurity from 2003 to 2022: a bibliometric analysis

Background

In order to understand the research hotspots and trends in the field of retinopathy of prematurity (ROP), our study analyzed the relevant publications from 2003 to 2022 by using bibliometric analysis.

Methods

The Citespace 6.2.R3 system was used to analyze the publications collected from the Web of Science Core Collection (WoSCC) database.

Results

In total, 4,957 publications were included in this study. From 2003 to 2022, the number of publications gradually increased and peaked in 2022. The United States was the country with the most publications, while Harvard University was the most productive institution. The top co-cited journal PEDIATRICS is published by the United States. Author analysis showed that Hellström A was the author with the most publications, while Good WV was the top co-cited author. The co-citation analysis of references showed seven major clusters: genetic polymorphism, neurodevelopmental outcome, threshold retinopathy, oxygen-induced retinopathy, low birth weight infant, prematurity diagnosis cluster and artificial intelligence (AI). For the citation burst analysis, there remained seven keywords in their burst phases until 2022, including ranibizumab, validation, trends, type 1 retinopathy, preterm, deep learning and artificial intelligence.

Conclusion

Intravitreal anti-vascular endothelial growth factor therapy and AI-assisted clinical decision-making were two major topics of ROP research, which may still be the research trends in the coming years.

Is There a Relationship Between First-Trimester Aneuploidy Screening Serum Biomarker Values and Nuchal Translucency Measurements and the Development of Retinopathy of Prematurity (ROP) in Premature Infants?

Purpose The purpose of this study is the evaluation of serum biomarker and nuchal translucency (NT) values measured during first-trimester aneuploidy screening in terms of the development of retinopathy of prematurity (ROP) in premature infants and investigation of whether the development of ROP is associated with these parameters. Methods In this retrospective cohort study, 3,750 premature infants who underwent ROP screening from 2016 to 2021 were identified from the hospital medical record system. Among 2,130 premature babies screened for first-trimester aneuploidy, 166 babies whose mothers had single pregnancies were screened by the same method and showed the same clinical course in both eyes were included in the study. The infants were divided into two groups according to the presence of ROP, and those with ROP were further evaluated in two groups according to the presence of proliferation. The groups were compared in terms of the serum values of human chorionic gonadotropin and pregnancy-associated plasma protein A, among aneuploidy screening biomarkers, and NT measurements. Results There was no significant difference in the evaluated serum biomarker values and NT measurements between the ROP and non-ROP groups or between the proliferative ROP, non-proliferative ROP, and non-ROP groups. Conclusion Our results showed that first-trimester aneuploidy screening serum biomarker values and NT measurements were not associated with the development of ROP in premature infants.

Retinopathy of prematurity: from oxygen management to molecular manipulation

INTRODUCTION

Retinopathy of prematurity (ROP) is a vasoproliferative disorder of the premature retina with the potential to progress to extraretinal neovascularisation. This review serves as an introduction to retinopathy of prematurity (ROP), outlining key parts of ROP pathophysiology, diagnosis and treatment. ROP is traditionally diagnosed by indirect ophthalmoscopy and classified using anatomical zones, stages of disease, and the presence or absence of "plus disease" (dilation and tortuosity of the major retinal arterioles and venules). ROP has a bi-phasic pathophysiology: initial hyperoxia causes reduced retinal vascularisation, followed by pathological vaso-proliferation resulting from subsequent hypoxia and driven by vascular endothelial growth factor (VEGF).

ADVANCEMENTS IN MANAGEMENT

This review summarises previous trials to establish optimum oxygen exposure levels in newborns and more recently the development of anti-VEGF agents locally delivered to block pathological neovascularisation, which is technically easier to administer and less destructive than laser treatment.

FUTURE DIRECTIONS

There remains an ongoing concern regarding the potential unwanted systemic effects of intravitreally administered anti-VEGF on the overall development of the premature baby. Ongoing dosing studies may lessen these fears by identifying the minimally effective dose required to block extraretinal neovascularisation.

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.

Safety and efficacy of intravitreal anti vascular endothelial growth factor for severe posterior retinopathy of prematurity with flat fibrovascular proliferation

BACKGROUND

Intravitreal anti-vascular endothelial growth factor (IVA) injection is known to cause contraction of fibrovascular proliferation (FVP), when present in severe retinopathy of prematurity (ROP).

AIM

To assess the structural outcomes of IVA injection in the treatment of severe posterior ROP with significant FVP.

METHODS

It was a retrospective study in which 36 eyes of 18 preterm babies who developed > 4 clock hours of FVP in zone I or posterior zone II, were treated with either intravitreal 0.625 mg bevacizumab or intravitreal 0.2 mg of ranibizumab. Favorable structural outcome included resolution of plus disease and FVP without the development of tractional retinal detachment. Secondary outcome measure included either full retinal maturation at follow-up or development of recurrent disease requiring additional treatment. Adverse outcomes included progression to retinal detachment.

RESULTS

The mean gestational age of the 18 preterm babies was 30 wk (range 27-36), and mean birth weight was 1319 g (range 650-1980 g). Mean post-menstrual age (PMA) at the time of primary treatment was 35.5 wk (range 31-41 wk). All eyes showed regression of plus disease and FVP. 5 eyes of 3 babies showed reactivation of disease and were treated with repeat IVA (n = 2 eyes) or peripheral laser photocoagulation (n = 3 eyes) respectively. 16 out of 36 (44%) reached retinal vascular maturation at final follow up at 5 years.

CONCLUSION

There was good resolution of severe posterior ROP with FVP with IVA, with retinal maturity of 44% at 5 year follow-up and a reactivation rate of 13.8%. When the IVA injection is given prior to 37 wk PMA, while disease is in phase 2, it is less likely to cause contracture of pre-existing FVP.

Jeddah Retinopathy of Prematurity (JED-ROP) Screening Algorithm

Background. The Jeddah retinopathy of prematurity (JED-ROP) algorithm, which is more specific to the population in Saudi Arabia, was established to decrease the number of infants screened without missing type 1 ROP cases. Methods. The data reviewed were birth weight (BW), gestational age (GA), weekly postnatal weight gain (PWG), and relevant perinatal risk factors. The sensitivities and specificities for detecting type 1 ROP were calculated. Results. Of the 502 infants included in the study, 148 developed ROP. The JED-ROP algorithm demonstrated 100% sensitivity and 38.9% specificity for recommending the screening of infants with GA ≤30 weeks and BW <1501 g and blood transfused <6 weeks and/or 3-week PWG <100 g in the type 1 ROP group. Conclusion. The JED-ROP algorithm can reduce the number of infants requiring ROP screening by 35.7% without missing type 1 ROP. The algorithm can be an adjunct to current national screening guidelines.

Association of Surgical Necrotizing Enterocolitis and Its Timing with Retinopathy of Prematurity

OBJECTIVE

The study aimed to determine the association of surgical necrotizing enterocolitis (NEC) and its timing, with the development and timing of retinopathy of prematurity (ROP).

STUDY DESIGN

This was a secondary data analysis of 7,483 preterm infants from the Postnatal Growth and Retinopathy of Prematurity Study. Associations between infants with surgical NEC, early-onset surgical NEC (8-28 days), and late-onset surgical NEC (over 28 days) with ROP were evaluated by using multivariable logistic regression models, controlling for birth weight, gestational age, small for gestational age status, chronic lung disease, intraventricular hemorrhage, hydrocephalus, patent ductus arteriosus, and periventricular leukomalacia.

RESULTS

Three hundred fifty-six (4.8%) infants had surgical NEC, with 56% having early surgical NEC. Infants with surgical NEC had a higher risk of any ROP and severe ROP (adjusted odds ratio [OR]: 2.7; 95% CI: 1.9-3.7) and 2.5 (95% CI: 1.9-3.3), respectively; p < 0.001) compared with infants without surgical NEC. Infants with early surgical NEC were at the highest risk of developing ROP and severe ROP (adjusted OR: 3.1 [95% CI: 2.1-4.8], and 3.3 [95% CI: 2.3-4.7] respectively, p < 0.001). Infants with late surgical NEC were also at increased risk of developing ROP and severe ROP (adjusted OR: 2.1 [95% CI: 1.3-3.4], and 1.9 [95% CI: 1.3-2.8] respectively, p < 0.001) compared with infants without surgical NEC.

CONCLUSION

Infants with surgical NEC, especially early surgical NEC, are at higher risk of ROP and severe ROP.

KEY POINTS

· Infants with surgical NEC are at higher risk of ROP and severe ROP than those without surgical NEC.. · Increased ROP risk is seen in infants with both early- or later onset surgical NEC.. · Early-onset surgical NEC is associated with a higher ROP risk compared with later onset surgical NEC..

Retinopathy of Prematurity: The Role of Nutrition

Retinopathy of prematurity (ROP) is a leading cause of childhood blindness. ROP occurs in infants who are born very preterm. In ROP, retinal blood vessel development, which is prematurely arrested in preterm infants, is altered by perinatal exposures like oxygen and inflammation. Optimizing nutritional practices for preterm infants may mitigate the risk of ROP. In this article, we review the evidence that postnatal growth, hyperglycemia, polyunsaturated fatty acids, and breast milk provision may affect ROP risk. We also outline the current management strategies for ROP and describe the vision outcomes of children affected by ROP. [Pediatr Ann. 2023;52(8):e303-e308.].

Validation of the postnatal growth and retinopathy of prematurity (G-ROP) screening criteria in a Thai cohort

PURPOSE

To validate Postnatal Growth and Retinopathy of Prematurity (G-ROP) criteria for Thai infants.

STUDY DESIGN

A retrospective review of infants receiving ROP screening during 2009-2020.

METHODS

Baseline characteristics, clinical progression and final ROP outcomes were collected. G-ROP was applied to infants who met at least one of the following 6 criteria: birth weight (BW) below 1051 g, gestational age (GA) under 28 weeks, weight gain (WG) less than 120 g during postnatal day 10-19, WG less than 180 g during day 20-29, WG less than 170 g during day 30-39 and hydrocephalus.

RESULTS

A total of 684 infants (boys, 53.4%) were included. Median (IQR) BW was 1200 (960-1470) grams and median GA was 30 (28-32) weeks. Prevalence of ROP was 26.6%, with 28 (4.1%) having type 1, 19 (2.8%) type 2 and, 135 (19.7%) having other ROP. Treatment was performed in 26 infants (3.8%). Sensitivity of G-ROP to include type 1, 2 or treatment-requiring ROP cases was 100% with 36.9% specificity, excluding 235 (34.4%) cases of unnecessary screening. To adjust for our setting of initial eye examination at 4 weeks' postnatal date, the last 2 criteria of G-ROP were replaced by the occurrence of grade 3 or 4 intraventricular hemorrhage (IVH). This modified G-ROP criteria yielded 100% sensitivity, 42.5% specificity and excluded 271 (39.6%) cases of unnecessary screening.

CONCLUSION

G-ROP criteria can be applied to our hospital setting. Occurrence of IVH grade 3 or 4 was proposed as an alternative in modified G-ROP criteria.

Retinopathy of prematurity: risk stratification by gestational age

OBJECTIVE

To identify gestational age (GA) specific risk factors for severe ROP (sROP).

STUDY DESIGN

Single-center cohort stratified by GA into <24 weeks, 24-26 weeks and ≥27 weeks.

RESULTS

132/1106 (11.9%) developed sROP. Time to full feeds was the only risk factor [HR 1.003 (1.001-1.006), p = 0.04] for infants<24 weeks GA. For infants 24-26 weeks GA, a higher GA was protective [HR 0.66 (0.51-0.85), p < 0.01], whereas steroids for bronchopulmonary dysplasia (BPD) [HR 2.21 (1.28-3.26), p < 0.01], patent ductus arteriosus (PDA) ligation [HR 1.99 (1.25-3.11), p < 0.01] and use of nitric oxide [HR 1.96 (1.11-3.30), p = 0.01] increased the hazard of sROP. Increasing birthweight was protective [HR 0.70 (0.54-0.89), p < 0.01] in infants ≥27 weeks GA. Cumulative hazard of sROP reached 1.0 by fifteen weeks for <24 weeks GA, 0.4 by twenty weeks for 24-26 weeks GA, and 0.05 by twenty weeks after birth for ≥27 weeks GA.

CONCLUSIONS

Risk factors, cumulative hazard, and time to sROP vary by GA.

Prevention of Chronic Morbidities in Extremely Premature Newborns with LISA-nCPAP Respiratory Therapy and Adjuvant Perinatal Strategies

Less invasive surfactant administration techniques, together with nasal continuous airway pressure (LISA-nCPAP) ventilation, an emerging noninvasive ventilation (NIV) technique in neonatology, are gaining more significance, even in extremely premature newborns (ELBW), under 27 weeks of gestational age. In this review, studies on LISA-nCPAP are compiled with an emphasis on short- and long-term morbidities associated with prematurity. Several perinatal preventative and therapeutic investigations are also discussed in order to start integrated therapies as numerous organ-saving techniques in addition to lung-protective ventilations. Two thirds of immature newborns can start their lives on NIV, and one third of them never need mechanical ventilation. With adjuvant intervention, these ratios are expected to be increased, resulting in better outcomes. Optimized cardiopulmonary transition, especially physiologic cord clamping, could have an additively beneficial effect on patient outcomes gained from NIV. Organ development and angiogenesis are strictly linked not only in the immature lung and retina, but also possibly in the kidney, and optimized interventions using angiogenic growth factors could lead to better morbidity-free survival. Corticosteroids, caffeine, insulin, thyroid hormones, antioxidants, N-acetylcysteine, and, moreover, the immunomodulatory components of mother's milk are also discussed as adjuvant treatments, since immature newborns deserve more complex neonatal interventions.

Angiogenic signaling pathways and anti-angiogenic therapy for cancer

Angiogenesis, the formation of new blood vessels, is a complex and dynamic process regulated by various pro- and anti-angiogenic molecules, which plays a crucial role in tumor growth, invasion, and metastasis. With the advances in molecular and cellular biology, various biomolecules such as growth factors, chemokines, and adhesion factors involved in tumor angiogenesis has gradually been elucidated. Targeted therapeutic research based on these molecules has driven anti-angiogenic treatment to become a promising strategy in anti-tumor therapy. The most widely used anti-angiogenic agents include monoclonal antibodies and tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor (VEGF) pathway. However, the clinical benefit of this modality has still been limited due to several defects such as adverse events, acquired drug resistance, tumor recurrence, and lack of validated biomarkers, which impel further research on mechanisms of tumor angiogenesis, the development of multiple drugs and the combination therapy to figure out how to improve the therapeutic efficacy. Here, we broadly summarize various signaling pathways in tumor angiogenesis and discuss the development and current challenges of anti-angiogenic therapy. We also propose several new promising approaches to improve anti-angiogenic efficacy and provide a perspective for the development and research of anti-angiogenic therapy.

Pilot dose-ranging of rhIGF-1/rhIGFBP-3 in a preterm lamb model of evolving bronchopulmonary dysplasia

BACKGROUND

Low levels of insulin-like growth factor-1 (IGF-1) protein in preterm human infants are associated with bronchopulmonary dysplasia (BPD). We used our preterm lamb model of BPD to determine (1) dosage of recombinant human (rh) IGF-1 bound to binding protein-3 (IGFBP-3) to reach infant physiologic plasma levels; and (2) whether repletion of plasma IGF-1 improves pulmonary and cardiovascular outcomes.

METHODS

Group 1: normal, unventilated lambs from 128 days gestation through postnatal age 5 months defined normal plasma levels of IGF-1. Group 2: continuous infusion of rhIGF-1/rhIGFBP-3 (0.5, 1.5, or 4.5 mg/kg/day; n = 2) for 3 days in mechanically ventilated (MV) preterm lambs determined that 1.5 mg/kg/day dosage attained physiologic plasma IGF-1 concentration of ~125 ng/mL, which was infused in four more MV preterm lambs.

RESULTS

Group 1: plasma IGF-1 protein increased from ~75 ng/mL at 128 days gestation to ~220 ng/L at 5 months. Group 2: pilot study of the optimal dosage (1.5 mg/kg/day rhIGF-1/rhIGFBP-3) in six MV preterm lambs significantly improved some pulmonary and cardiovascular outcomes (p < 0.1) compared to six MV preterm controls. RhIGF-1/rhIGFBP-3 was not toxic to the liver, kidneys, or lungs.

CONCLUSIONS

Three days of continuous iv infusion of rhIGF-1/rhIGFBP-3 at 1.5 mg/kg/day improved some pulmonary and cardiovascular outcomes without toxicity.

IMPACT

Preterm birth is associated with rapid decreases in serum or plasma IGF-1 protein level. This decline adversely impacts the growth and development of the lung and cardiovascular system. For this pilot study, continuous infusion of optimal dosage of rhIGF-1/rhIGFBP-3 (1.5 mg/kg/day) to maintain physiologic plasma IGF-1 level of ~125 ng/mL during mechanical ventilation for 3 days statistically improved some structural and biochemical outcomes related to the alveolar formation that would favor improved gas exchange compared to vehicle-control. We conclude that 3 days of continuous iv infusion of rhIGF-1/rhIGFBP-3 improved some physiological, morphological, and biochemical outcomes, without toxicity, in mechanically ventilated preterm lambs.

Perinatal origins of bronchopulmonary dysplasia-deciphering normal and impaired lung development cell by cell

Bronchopulmonary dysplasia (BPD) is a multifactorial disease occurring as a consequence of premature birth, as well as antenatal and postnatal injury to the developing lung. BPD morbidity and severity depend on a complex interplay between prenatal and postnatal inflammation, mechanical ventilation, and oxygen therapy as well as associated prematurity-related complications. These initial hits result in ill-explored aberrant immune and reparative response, activation of pro-fibrotic and anti-angiogenic factors, which further perpetuate the injury. Histologically, the disease presents primarily by impaired lung development and an arrest in lung microvascular maturation. Consequently, BPD leads to respiratory complications beyond the neonatal period and may result in premature aging of the lung. While the numerous prenatal and postnatal stimuli contributing to BPD pathogenesis are relatively well known, the specific cell populations driving the injury, as well as underlying mechanisms are still not well understood. Recently, an effort to gain a more detailed insight into the cellular composition of the developing lung and its progenitor populations has unfold. Here, we provide an overview of the current knowledge regarding perinatal origin of BPD and discuss underlying mechanisms, as well as novel approaches to study the perturbed lung development.

Retinopathy of prematurity: A review of pathophysiology and signaling pathways

Retinopathy of prematurity (ROP) is a vasoproliferative disorder of the retina and a leading cause of visual impairment and childhood blindness worldwide. The disease is characterized by an early stage of retinal microvascular degeneration, followed by neovascularization that can lead to subsequent retinal detachment and permanent visual loss. Several factors play a key role during the different pathological stages of the disease. Oxidative and nitrosative stress and inflammatory processes are important contributors to the early stage of ROP. Nitric oxide synthase and arginase play important roles in ischemia/reperfusion-induced neurovascular degeneration. Destructive neovascularization is driven by mediators of the hypoxia-inducible factor pathway, such as vascular endothelial growth factor and metabolic factors (succinate). The extracellular matrix is involved in hypoxia-induced retinal neovascularization. Vasorepulsive molecules (semaphorin 3A) intervene preventing the revascularization of the avascular zone. This review focuses on current concepts about signaling pathways and their mediators, involved in the pathogenesis of ROP, highlighting new potentially preventive and therapeutic modalities. A better understanding of the intricate molecular mechanisms underlying the pathogenesis of ROP should allow the development of more effective and targeted therapeutic agents to reduce aberrant vasoproliferation and facilitate physiological retinal vascular development.

Systemic Cytokines in Retinopathy of Prematurity

Retinopathy of prematurity (ROP), a vasoproliferative vitreoretinal disorder, is the leading cause of childhood blindness worldwide. Although angiogenic pathways have been the main focus, cytokine-mediated inflammation is also involved in ROP etiology. Herein, we illustrate the characteristics and actions of all cytokines involved in ROP pathogenesis. The two-phase (vaso-obliteration followed by vasoproliferation) theory outlines the evaluation of cytokines in a time-dependent manner. Levels of cytokines may even differ between the blood and the vitreous. Data from animal models of oxygen-induced retinopathy are also valuable. Although conventional cryotherapy and laser photocoagulation are well established and anti-vascular endothelial growth factor agents are available, less destructive novel therapeutics that can precisely target the signaling pathways are required. Linking the cytokines involved in ROP to other maternal and neonatal diseases and conditions provides insights into the management of ROP. Suppressing disordered retinal angiogenesis via the modulation of hypoxia-inducible factor, supplementation of insulin-like growth factor (IGF)-1/IGF-binding protein 3 complex, erythropoietin, and its derivatives, polyunsaturated fatty acids, and inhibition of secretogranin III have attracted the attention of researchers. Recently, gut microbiota modulation, non-coding RNAs, and gene therapies have shown promise in regulating ROP. These emerging therapeutics can be used to treat preterm infants with ROP.

Postnatal serum IGF-1 levels associate with brain volumes at term in extremely preterm infants

BACKGROUND

Growth factors important for normal brain development are low in preterm infants. This study investigated the link between growth factors and preterm brain volumes at term.

MATERIAL/METHODS

Infants born <28 weeks gestational age (GA) were included. Endogenous levels of insulin-like growth factor (IGF)-1, brain-derived growth factor, vascular endothelial growth factor, and platelet-derived growth factor (expressed as area under the curve [AUC] for serum samples from postnatal days 1, 7, 14, and 28) were utilized in a multivariable linear regression model. Brain volumes were determined by magnetic resonance imaging (MRI) at term equivalent age.

RESULTS

In total, 49 infants (median [range] GA 25.4 [22.9-27.9] weeks) were included following MRI segmentation quality assessment and AUC calculation. IGF-1 levels were independently positively associated with the total brain (p < 0.001, β = 0.90), white matter (p = 0.007, β = 0.33), cortical gray matter (p = 0.002, β = 0.43), deep gray matter (p = 0.008, β = 0.05), and cerebellar (p = 0.006, β = 0.08) volume adjusted for GA at birth and postmenstrual age at MRI. No associations were seen for other growth factors.

CONCLUSIONS

Endogenous exposure to IGF-1 during the first 4 weeks of life was associated with total and regional brain volumes at term. Optimizing levels of IGF-1 might improve brain growth in extremely preterm infants.

IMPACT

High serum levels of insulin-like growth factor (IGF)-1 during the first month of life were independently associated with increased total brain volume, white matter, gray matter, and cerebellar volume at term equivalent age in extremely preterm infants. IGF-1 is a critical regulator of neurodevelopment and postnatal levels are low in preterm infants. The effects of IGF-1 levels on brain development in extremely preterm infants are not fully understood. Optimizing levels of IGF-1 may benefit early brain growth in extremely preterm infants. The effects of systemically administered IGF-1/IGFBP3 in extremely preterm infants are now being investigated in a randomized controlled trial (Clinicaltrials.gov: NCT03253263).

Platelets and (Lymph)angiogenesis

The formation of new blood and lymphatic vessels is essential for both the development of multicellular organisms and (patho)physiological processes like wound repair and tumor growth. In the 1990s, circulating blood platelets were first postulated to regulate tumor angiogenesis by interacting with the endothelium and releasing angiogenic regulators from specialized α granules. Since then, many studies have validated the contributions of platelets to tumor angiogenesis, while uncovering novel roles for platelets in other angiogenic processes like wound resolution and retinal vascular disease. Although the majority of (lymph)angiogenesis occurs during development, platelets appear necessary for lymphatic but not vascular growth, implying their particular importance in pathological cases of adult angiogenesis. Future work is required to determine whether drugs targeting platelet production or function offer a clinically relevant tool to limit detrimental angiogenesis.

Understanding Ischemic Retinopathies: The Role of Succinate and Its Receptor in Retinal Pigment Epithelium

Retinopathy is the general name for all condition of the eyes in which blood vessels that supply oxygen to the retina are damaged. These include diabetic retinopathy, retinopathy of prematurity, hypertensive retinopathy, and arteriosclerotic retinopathy. Although the initial trigger that leads to insufficient perfusion of the retina may be different, once a critical level of ischemia is achieved, all types of retinopathies seem to follow a common sequence-oxidative stress, followed by hypoxia-induced formation of morphologically abnormal vessels. This preretinal vascular growth is the most severe aspect of the retinopathy, as the outcome is often retinal detachment and eventually blindness. Regardless of which therapy strategy is followed, a deeper understanding of both normal retinal growth and the underlying molecular mechanisms of retinopathies is needed in order to come up with more effective therapies. This chapter focuses on the citric acid cycle intermediate succinate and its G protein-coupled receptor SUCNR1 in ischemic retinopathies, which were identified as potent mediators of vessel growth in the settings of both normal retinal development and proliferative ischemic retinopathies.

The Determinative Role of Cytokines in Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a neonatal disease corresponding to vision impairment and blindness. Utilizing the pathogenesis of ROP and the risk factors affecting its progression can help prevent and reduce its incidence and lead to the emergence and development of new treatment strategies. Factors influencing retinopathy include growth and inflammatory factors that play an essential role in the pathogenesis of the ROP. This review summarizes the most critical factors in the pathogenesis of ROP.

Is thrombocytopenia and postnatal weight gain associated with treatment‐requiring retinopathy of prematurity? A matched case–control study

PURPOSE

The purpose of the study was to investigate the association of platelet parameters and postnatal weight gain with treatment-requiring ROP (TR-ROP).

METHODS

In this retrospective matched case-control study, infants with TR-ROP were individually matched, according to gestational age and birth weight, with one or two untreated infants who developed no or spontaneously regressed ROP. Longitudinal data on platelet count (PLT), mean platelet volume (MPV), daily weight and platelet transfusions were collected. Platelet mass index (PMI) and weight standard deviation score (WSDS) were also calculated. Conditional logistic regression analysis was performed to adjust for matching.

RESULTS

Fourteen cases, presenting type I ROP, and 25 matched controls were included. The odds of developing TR-ROP decreased as PLT increased during 31^st week of postmenstrual age (PMA) or during 1^st and 2^nd week of postnatal age (PNA). The odds of developing TR-ROP were 16.7 times higher in infants receiving at least one platelet transfusion compared with those who were not transfused. The odds of developing TR-ROP increased by 31.2% as the mean volume of platelet transfusion per infant increased by 1 ml. The odds of developing TR-ROP decreased as PMI increased during 1^st week PNA, and as weight and WSDS increased during 4^th -6^th week PNA. Analysis of MPV, number of thrombopenic episodes per infant, number of platelet transfusions per infant and days with WSDS < -2 showed no association with TR-ROP.

CONCLUSION

To our knowledge, this is the first study ascertaining an association of platelet transfusions with type I ROP. Prospective cohort studies are required to confirm our findings.

Molecular mechanism of VEGF and its role in pathological angiogenesis

Over the last seven decades, a significant scientific contribution took place in the delineation of the implications of vascular endothelial-derived growth factor (VEGF) in the processes of angiogenesis. Under pathological conditions, mainly in response to hypoxia or ischemia, elevated VEGF levels promote vascular damage and the growth of abnormal blood vessels. Indeed, the development of VEGF biology has revolutionized our understanding of its role in pathological conditions. Hence, targeting VEGF or VEGF-mediated molecular pathways could be an excellent therapeutic strategy for managing cancers and intraocular neovascular disorders. Although anti-VEGF therapies, such as monoclonal antibodies and small-molecule tyrosine kinase inhibitors, have limited clinical efficacy, they can still significantly improve the overall survival rate. This thus demands further investigation through the development of alternative strategies in the management of VEGF-mediated pathological angiogenesis. This review article focuses on the recent developments toward the delineation of the functional biology of VEGF and the role of anti-VEGF strategies in the management of tumor and eye pathologies. Moreover, therapeutic angiogenesis, an exciting frontier for the treatment of ischemic disorders, is highlighted in this review, including wound healing.

Retinopathy of prematurity: Metabolic risk factors

At preterm birth, the retina is incompletely vascularized. Retinopathy of prematurity (ROP) is initiated by the postnatal suppression of physiological retinal vascular development that would normally occur in utero. As the neural retina slowly matures, increasing metabolic demand including in the peripheral avascular retina, leads to signals for compensatory but pathological neovascularization. Currently, only late neovascular ROP is treated. ROP could be prevented by promoting normal vascular growth. Early perinatal metabolic dysregulation is a strong but understudied risk factor for ROP and other long-term sequelae of preterm birth. We will discuss the metabolic and oxygen needs of retina, current treatments, and potential interventions to promote normal vessel growth including control of postnatal hyperglycemia, dyslipidemia and hyperoxia-induced retinal metabolic alterations. Early supplementation of missing nutrients and growth factors and control of supplemental oxygen promotes physiological retinal development. We will discuss the current knowledge gap in retinal metabolism after preterm birth.

Role of Oxidative Stress in Retinal Disease and the Early Intervention Strategies: A Review

The retina, owing to its cellular anatomy and physical location, is susceptible to generating reactive oxygen species (ROS), which are associated with several major retinal diseases. When ROS exceeds the body's natural antioxidants, the retina is in a state of oxidative stress, which is recognized as the pathogenesis of retinal diseases. The early stage of the pathogenic process is an adaptive change in which oxidative stress and endogenous defense mechanisms occur. If no treatment is applied, the retinal diseases will progress to the pathological stage with neuronal and vascular dysfunction or damage and even blindness. This review summarizes the role of oxidative stress in several common retinal diseases, including retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy, glaucoma, and retinopathy of prematurity. In addition, we discuss the early intervention strategies for these diseases. An outline is provided to identify potential intervention targets for further research. Early intervention for retinal diseases is necessary and urgent and may offer hope to improve patients' quality of life through functional vision.

Association of umbilical cord insulin-like growth factor 1 levels with severe retinopathy in extremely preterm infants

BACKGROUND

The association between umbilical cord blood insulin-like growth factor 1 (IGF-1) levels and retinopathy of prematurity (ROP) remains unclear. This study aimed to investigate whether umbilical cord blood IGF-1 levels can predict the development of severe ROP in extremely preterm infants.

METHODS

This hospital-based retrospective cohort study included infants born at <37 weeks gestational age (GA) between 2019 and 2021 and then classified them into the two GA groups: extremely preterm, <28 weeks and preterm infants, 28-36 weeks. Extremely preterm infants were further subclassified into two groups according to the laser treatment as follows: the severe ROP (ROP-Tx) and ROP (No ROP-Tx) groups. Median umbilical cord blood IGF-1 values were compared between the groups. Perinatal risk factors were identified by univariate and multivariate analyses. Finally, umbilical cord IGF-1 cut-off values requiring ROP treatment with laser were determined by receiver operating characteristic (ROC) curve analyses.

RESULTS

A total of 205 infants were enrolled, with 32 being extremely preterm (ROP-Tx: n = 11; No ROP-Tx: n = 21) and 173 being preterm. IGF-1 levels were significantly lower in extremely preterm (13.5 ng/mL) than preterm infants (36 ng/mL, p < 0.001). In extremely preterm infants, IGF-1 levels were significantly lower in the ROP-Tx group than the No ROP-Tx group (10 vs. 19 ng/mL, respectively, p = 0.024). Only GA, umbilical cord blood IGF-1 levels, birth head circumference, and birth chest circumference were identified as risk factors by univariate analysis (p < 0.05). Multivariate analysis showed that only umbilical cord blood IGF-1 was an independent risk factor (odds ratio: 1.26, p = 0.021). ROC curves revealed an IGF-1 cut-off value of 14 ng/mL.

CONCLUSION

The need of laser treatment for ROP was found to be associated with low umbilical cord blood IGF-1 levels in extremely preterm infants. Umbilical cord blood IGF-1 can be used as a biomarker for the risk of developing severe ROP.

Daily Oxygen Supplementation and Risk of Retinopathy of Prematurity

PURPOSE

Excessive oxygen supplementation increases risk of retinopathy of prematurity (ROP). While numerous oxygen parameters could be considered when predicting ROP (saturation targets, actual saturation, fraction of inspired oxygen, etc.), complicated measures are impractical as screening criteria. We sought to develop a simple, clinically useful measure of daily oxygen supplementation during ages 0-28 days to improve prediction of ROP.

METHODS

Secondary analysis of two Postnatal Growth and ROP (G-ROP) Study cohorts (G-ROP-1 and G-ROP-2) at 45 hospitals. Infants with a known ROP outcome and complete oxygen data were included. Associations between severe ROP and days on supplemental oxygen (FiO2 > 21%), during ages 0-28 days (DSO28) were assessed, controlling for birth weight (BW) and gestational age (GA). New screening criteria incorporating DSO were developed and compared to current guidelines.

RESULTS

Among 8,949 studied infants, 459 (5.1%) developed type 1 ROP. DSO28 was associated with severe ROP (adjusted-OR 1.05 per day supplemental oxygen, 95%CI 1.03-1.07, p < .0001). The following criteria had 100% sensitivity for type 1 ROP and higher specificity than current guidelines: new BW/GA criteria with DSO (BW<901 g, GA<26 weeks, or DSO >3), 23.4% fewer infants examined; modified G-ROP criteria including DSO, 29.0% fewer infants; original G-ROP criteria, 31.8% fewer infants.

CONCLUSION

In high-level neonatal-care settings, incorporating DSO (a simple measure of oxygen supplementation) into screening criteria improves sensitivity and specificity for type 1 ROP over current BW-GA criteria, but does not perform as well as the validated G-ROP criteria.

Deletion of Tgfβ signal in activated microglia prolongs hypoxia-induced retinal neovascularization enhancing Igf1 expression and retinal leukostasis

Retinal neovascularization (NV) is the major cause of severe visual impairment in patients with ischemic eye diseases. While it is known that retinal microglia contribute to both physiological and pathological angiogenesis, the molecular mechanisms by which these glia regulate pathological NV have not been fully elucidated. In this study, we utilized a retinal microglia-specific Transforming Growth Factor-β (Tgfβ) receptor knock out mouse model and human iPSC-derived microglia to examine the role of Tgfβ signaling in activated microglia during retinal NV. Using a tamoxifen-inducible, microglia-specific Tgfβ receptor type 2 (Tgfβr2) knockout mouse [Tgfβr2 KO (ΔMG)] we show that Tgfβ signaling in microglia actively represses leukostasis in retinal vessels. Furthermore, we show that Tgfβ signaling represses expression of the pro-angiogenic factor, Insulin-like growth factor 1 (Igf1), independent of Vegf regulation. Using the mouse model of oxygen-induced retinopathy (OIR) we show that Tgfβ signaling in activated microglia plays a role in hypoxia-induced NV where a loss in Tgfβ signaling microglia exacerbates and prolongs retinal NV in OIR. Using human iPSC-derived microglia cells in an in vitro assay, we validate the role of Transforming Growth Factor-β1 (Tgfβ1) in regulating Igf1 expression in hypoxic conditions. Finally, we show that Tgfβ signaling in microglia is essential for microglial homeostasis and that the disruption of Tgfβ signaling in microglia exacerbates retinal NV in OIR by promoting leukostasis and Igf1 expression.

New Aspects on the Treatment of Retinopathy of Prematurity: Currently Available Therapies and Emerging Novel Therapeutics

Retinopathy of prematurity (ROP) is a rare proliferative ocular disorder in preterm infants. Because of the advancements in neonatal care, the incidence of ROP has increased gradually. Now, ROP is one of the leading causes of blindness in children. Preterm infants with immature retinal development are exposed to supplemental oxygen inside an incubator until their cardiopulmonary system is adequately developed. Once they are returned to room air, the relatively low oxygen level stimulates various angiogenesis factors initiating retinal neovascularization. If patients with ROP are not offered adequate and timely treatment, they can experience vision loss that may ultimately lead to permanent blindness. Although laser therapy and anti-vascular endothelial growth factor agents are widely used to treat ROP, they have limitations. Thus, it is important to identify novel therapeutics with minimal adverse effects for the treatment of ROP. To date, various pharmacologic and non-pharmacologic therapies have been assessed as treatments for ROP. In this review, the major molecular factors involved in the pathogenesis of ROP, currently offered therapies, therapies under investigation, and emerging novel therapeutics of ROP are discussed.

The Serum Levels of Asymmetric Dimethylarginine, Vascular Endothelial Growth Factor, and Insulin-Like Growth Factor-1 in Preterms with Retinopathy of Prematurity

Objective:To determine the serum levels of asymmetric dimethylarginine (ADMA), vascular endothelial growth factor (VEGF), and insulin-like growth factor-1 (IGF-1) in preterms with retinopathy of prematurity (ROP). Materials and Methods: We included 37 preterm infants. The first blood samples were obtained within the first 5 days of life and repeated at the time of the first ophthalmologic examination for ROP. The levels of ADMA, IGF-1, and VEGF were measured in all samples. Results: ROP was detected in 12 of the subjects (32.4%). We categorized the subjects as non-ROP (Group 1; n = 25), untreated ROP (Group 2; n = 7), and treated ROP (Group 3; n = 5) according to the eye findings. There were no significant differences among the groups for serum levels of ADMA, VEGF, and IGF-1 at the first sampling. Conclusion: We did not find any differences in terms of serum ADMA, IGF-1, and VEGF levels in preterm infants with or without ROP.

Postnatal Growth Trajectories and Neurodevelopmental Outcomes Following Bevacizumab Treatment for Retinopathy of Prematurity

Purpose

To investigate the postnatal growth and neurodevelopment of infants with retinopathy of prematurity (ROP) treated with intravitreal bevacizumab (IVB).

Patients and Methods

This was a retrospective comparative study. A total of 262 infants were divided among three study groups: 22 treated with intravitreal bevacizumab, 55 treated with laser, and 185 with ROP that resolved without treatment. Infants with nonviable course or hydrocephalus, a source of non-physiologic weight gain, were excluded. Neurodevelopment was assessed with Bayley III scores at 17–28 months if available and presence of hearing loss or cerebral palsy. Weekly weight, height, and head circumference from birth through 50 weeks postmenstrual age (PMA) were modeled to determine differences in growth trajectories following treatment.

Results

Comparison of postnatal growth curves from the time of treatment to 50 weeks PMA showed no significant differences in growth trajectories between groups after adjusting for the corresponding growth parameters at birth. Comparison of Bayley scores in patients with available data (n = 120) showed no significant differences. There was an increased risk of cerebral palsy in the IVB group after logistic regression adjusting for baseline confounders, but this did not retain statistical significance after applying the false discovery rate correction for multiple testing.

Conclusion

To our knowledge, this is the first large retrospective study to examine longitudinal growth in infants treated with IVB compared to controls. There were no significant differences in postnatal growth or neurodevelopmental outcomes between groups, which overall continue to support the safety of bevacizumab treatment for ROP.

A systematic review and meta-analysis of preanalytical factors and methodological differences influencing the measurement of circulating vascular endothelial growth factor

BACKGROUND

Intraocular treatment with antibodies targeting vascular endothelial growth factor (anti-VEGF) inhibits pathological vessel growth in adults and preterm infants. Recently, concerns regarding the impact of anti-VEGF treatment on systemic VEGF levels in preterm infants have been raised. Earlier studies suggest that preanalytical and methodological parameters impact analytical VEGF concentrations, but we have not found a comprehensive systematic review covering preanalytical procedures and methods for VEGF measurements.

OBJECTIVE

This review aimed to evaluate the most critical factors during sample collection, sample handling, and the analytical methods that influence VEGF levels and therefore should be considered when planning a prospective collection of samples to get reproducible, comparable results.

MATERIAL AND METHODS

PubMed and Scopus databases were searched 2021/Nov/11. In addition, identification of records via other methods included reference, citation, and Google Scholar searches. Rayyan QCRI was used to handle duplicates and the selection process. Publications reporting preanalytical handling and/or methodological comparisons using human blood samples were included. Exclusion criteria were biological, environmental, genetic, or physiological factors affecting VEGF. The data extraction sheets included bias assessment using the QUADAS-2 tool, evaluating patient selection, index-test, reference standard, and flow and timing. Concentrations of VEGF and results from statistical comparisons of analytical methods and/or preanalytical sample handling and/or different sample systems were extracted. The publications covering preanalytical procedures were further categorized based on the stage of the preanalytical procedure. Meta-analysis was used to visualize VEGF concentrations among healthy individuals. The quality of evidence was rated according to GRADE.

RESULTS

We identified 1596 publications, and, after the screening process, 43 were considered eligible for this systematic review. The risk of bias estimation was difficult for 2/4 domains due to non-reported information. Four critical steps in the preanalytical process that impacted VEGF quantification were identified: blood drawing and the handling before, during, and after centrifugation. Sub-categorization of those elements resulted in nine findings, rated from moderate to very low evidence grade. The choice of sample system was the most reported factor. VEGF levels (mean [95% CI]) in serum (n = 906, 20 publications), (252.5 [213.1-291.9] pg/mL), were approximated to ninefold higher than in plasma (n = 1122, 23 publications), (27.8 [23.6-32.1] pg/mL), based on summarized VEGF levels with meta-analysis. Notably, most reported plasma levels were below the calibration range of the used method.

CONCLUSION

When measuring circulating VEGF levels, choice of sample system and sample handling are important factors to consider for ensuring high reproducibility and allowing study comparisons. Protocol: CRD42020192433.

Postnatal administration of systemic steroids increases severity of retinopathy in premature infants

BACKGROUND

Postnatal systemic steroids are known to increase the risk of developing retinopathy of prematurity (ROP). However, whether the total dosage and type of postnatal systemic steroids are related to the development and severity of ROP in premature infants remains unclear. This study was conducted to identify the risk factors for ROP and investigate the relationship between photocoagulation (PC)-demanding severe ROP and the postnatal dosage of any type of systemic steroids.

METHODS

A total of 75 infants born at <28 weeks of postmenstrual age (PMA) were enrolled. The number of PC procedures for ROP was evaluated as the objective variable. This study analyzed the following independent variables: gestational age; birth weight; sex; Apgar scores; duration of mechanical ventilation; duration of nasal intermittent positive pressure ventilation; mean saturation and mean oxygen concentration administration until 36 weeks of PMA; total accumulation dosage of hydrocortisone, dexamethasone, and systemic steroids; dosage number of times of erythropoietin; total dosage of red cell concentrates (RCC); incidence of necrotizing enterocolitis (NEC) and focal intestinal perforation; sepsis; bronchopulmonary dysplasia (BPD); and intraventricular hemorrhage (IVH). Logistic regression was used to estimate the relative risk (odds ratio (OR)) associated with risk factors for PC-demanding severe ROP.

RESULTS

Compared with infants in the non-PC group, PC-treated infants had younger gestational age, longer mechanical ventilation periods, and higher dosage of systemic steroids and dexamethasone. Multivariate logistic regression analysis revealed total dosage of systemic steroids as the only risk factor for PC-demanding severe ROP. Based on receiver operating characteristic (ROC) curve analysis, a cutoff value of 8.95 mg/kg of postnatal systemic steroid administration was identified as a useful marker to predict PC-demanding severe ROP.

CONCLUSION

By focusing on the method of systemic steroid administration and avoiding excessive doses for infants born at <28 weeks of PMA, preventing the development of severe ROP is possible.

Omega-3/Omega-6 Long-Chain Fatty Acid Imbalance in Phase I Retinopathy of Prematurity

There is a gap in understanding the effect of the essential ω-3 and ω-6 long-chain polyunsaturated fatty acids (LCPUFA) on Phase I retinopathy of prematurity (ROP), which precipitates proliferative ROP. Postnatal hyperglycemia contributes to Phase I ROP by delaying retinal vascularization. In mouse neonates with hyperglycemia-associated Phase I retinopathy, dietary ω-3 (vs. ω-6 LCPUFA) supplementation promoted retinal vessel development. However, ω-6 (vs. ω-3 LCPUFA) was also developmentally essential, promoting neuronal growth and metabolism as suggested by a strong metabolic shift in almost all types of retinal neuronal and glial cells identified with single-cell transcriptomics. Loss of adiponectin (APN) in mice (mimicking the low APN levels in Phase I ROP) decreased LCPUFA levels (including ω-3 and ω-6) in retinas under normoglycemic and hyperglycemic conditions. ω-3 (vs. ω-6) LCPUFA activated the APN pathway by increasing the circulating APN levels and inducing expression of the retinal APN receptor. Our findings suggested that both ω-3 and ω-6 LCPUFA are crucial in protecting against retinal neurovascular dysfunction in a Phase I ROP model; adequate ω-6 LCPUFA levels must be maintained in addition to ω-3 supplementation to prevent retinopathy. Activation of the APN pathway may further enhance the ω-3 and ω-6 LCPUFA's protection against ROP.