Correlation between cord blood apelin and IGF-1 levels in retinopathy of prematurity

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

PURPOSE

To determine the retinal transcriptomic differences underlying the oxygen-induced retinopathy phenotypes between Sprague Dawley rat pups from two commonly used commercial vendors. This will allow us to discover genes and pathways that may be related to differences in disease severity in similarly aged premature babies and suggest possible new treatment approaches.

METHODS

We analyzed retinal vascular morphometry and transcriptomes from Sprague Dawley rat pups from Charles River Laboratories and Envigo (previously Harlan). Room air control and oxygen-induced retinopathy groups were compared. Oxygen-induced retinopathy was induced with the rat 50/10 model.

RESULTS

Pups from Charles River Laboratories developed a more severe oxygen-induced retinopathy phenotype, with 3.6-fold larger percent avascular area at P15 and twofold larger % neovascular area at P20 than pups from Envigo. Changes in retinal transcriptomes of rat pups from both vendors were substantial at baseline and in response to oxygen-induced retinopathy. Baseline differences centered on activated pathways of neuronal development in Charles River Laboratories pups. In response to oxygen-induced retinopathy, during the neovascular phase, retinas from Charles River Laboratories pups exhibited activation of pathways regulating necrosis, neuroinflammation, and interferon signaling, supporting the observed increase of neovascularization. Conversely, retinas from Envigo pups showed decreased necrosis and increased focal adhesion kinase signaling, supporting more normal vascular development. Comparing oxygen-induced retinopathy transcriptomes at P15 to those at P20, canonical pathways such as phosphate and tensin homolog, interferon, and coordinated lysosomal expression and regulation element signaling were identified, highlighting potential novel mechanistic targets for future research.

CONCLUSION

Transcriptomic profiles differ substantially between rat pup retinas from Charles River Laboratories and Envigo at baseline and in response to oxygen-induced retinopathy, providing insight into vascular morphologic differences. Comparing transcriptomes identified new pathways for further research in oxygen-induced retinopathy pathogenesis and increased scientific rigor of this model.

Insulin-like growth factor-1 and retinopathy of prematurity: A systemic review and meta-analysis

The prevalence of retinopathy of prematurity (ROP) is rapidly increasing worldwide. Many researchers have explored the relationship between insulin-like growth factor-1 (IGF-1) and ROP; however, the results are controversial. This meta-analysis evaluates the correlation between IGF-1 and ROP systematically. We searched for PubMed, Web of Science, Embase, the Cochrane Central Register of Controlled Trials, Ovid MEDLINE, SinoMed, ClinicalTrials.gov, and 3 Chinese databases up to June 2022. Then, the meta-regression and subgroup analysis were carried out. Twelve articles with 912 neonates were included in this meta-analysis. The results revealed that 4 of 7 covariates account for significant heterogeneity: location, measurement method of IGF-1 levels, collection time of blood sample, and the severity of ROP. The pooled analysis showed that low IGF-1 levels could serve as a risk factor associated with the development and severity of ROP. Serum IGF-1 monitoring in preterm infants after birth will be helpful in the diagnosis and treatment of ROP, and the reference value of IGF-1 should be standardized according to the measurement of IGF-1 and the region, as well as the postmenstrual age of prematurity.

Plasma Level of Apelin as a Promising Factor for Retinopathy of Prematurity

INTRODUCTION

The aim of this study was to investigate the relevance of plasma levels of apelin and other risk factors in infants with retinopathy of prematurity (ROP).

METHODS

This was a single-center cross-sectional study. Fifty preterm infants with ROP and 50 preterm infants without ROP were enrolled. The analysis included evaluation of gestational age (GA), birth weight (BW), and measurement of plasma concentrations of apelin, vascular endothelial growth factor (VEGF), erythropoietin (EPO), and insulin-like growth factor (IGF-1) using enzyme-linked immunosorbent assay.

RESULTS

The mean BW and GA of babies with ROP were considerably lower than those without ROP (p < 0.001, p = 0.003, respectively). Plasma levels of VEGF, EPO, and IGF-1 were all lower in babies with ROP (all p < 0.001), while plasma apelin levels were greater (p < 0.001). We compared the sensitivity and selected the best cut-offs while keeping the specificity constant (80.0%). Among all the criteria, plasma apelin levels had the best sensitivity (72%), with the cut-off of 21.08 pg/mL. Multivariable logistic regression analyses showed that the plasma level of apelin was the only parameter associated with ROP (p = 0.02, OR = 16, 95% CI: 1.54-166.53). The area under the curve of the multivariable regression model that comprised GA, BW alone was 0.67, while that of the model that included apelin was 0.90.

CONCLUSIONS

Plasma apelin level demonstrated good sensitivity and specificity with regard to the association of ROP; the inclusion of apelin may be a promising factor to include in screening criteria.

Correlation between apelin and VEGF levels in retinopathy of prematurity: a matched case-control study

Background

Although several clinical studies have analysed the relationship between the levels of vascular endothelial growth factor (VEGF) and apelin-13 in venous blood and retinopathy of prematurity (ROP), no definitive conclusions have been reached. This study aimed to investigate the relationship between apelin-13 levels and VEGF levels and ROP.

Methods

Differences in plasma apelin-13 and VEGF levels were analysed in two groups of infants born with birth weight < 1500 g and gestational age < 32 weeks at Peking University People’ s Hospital. One group comprised infants diagnosed with ROP and the other group was a control group comprising infants without ROP.

Results

Apelin-13 levels were significantly lower in the ROP group than in the control group, while VEGF levels showed the opposite result (both P < 0.001). Infants with severe ROP had lower apelin-13 levels and higher VEGF levels than with mild ROP (both P < 0.05).The receiver operating characteristic curve for apelin-13 level as the indicator of ROP showed that a cut-off value of 119.6 pg/mL yielded a sensitivity of 84.8% and a specificity of 63.6%, while for VEGF level, the cut-off value of 84.3 pg/mL exhibited a sensitivity of 84.8% and a specificity of 66.7%.

Conclusions

Plasma apelin-13 and VEGF levels at 4–6 weeks of age may play a role in assisting the diagnosis of ROP.

Multiple roles of apelin/APJ system in eye diseases

Apelin is an endogenous ligand of G protein-coupled receptor (APJ), and they compose apelin/APJ system. Apelin/APJ system is widely distributed in tissues and plays pleiotropic roles. Attractively, more emphasis has recently been placed on the effects of apelin/APJ system in eye diseases, such as retinopathy of prematurity (ROP), diabetic retinopathy (DR) and diabetic macular edema (DME). In this review, we elaborated the roles of apelin/APJ system in the pathophysiological processes of eye. Concretely, apelin/APJ system induces retinal gliosis and angiogenesis. Hypoxia-inducible factors (HIFs) are involved in apelin/APJ system-triggered ROP progress. Apelin/APJ system mediates DR-induced retinopathy. Apelin/APJ system maintains retinal functions and health by protecting Müller cells from apoptosis. Apelin/APJ system suppresses the NMDA-induced retinal ganglion cell (RGC) loss to protect optic nerve damage. Overall, apelin/APJ system is a potential therapeutic target for eye disease.

APJ/apelin: a promising target for the treatment of retinopathy of prematurity

Retinopathy of prematurity is a noticeable retinal abnormality causing common blindness in children. An uncontrolled retinal vasculature in retinopathy of prematurity inflicts vision loss in numerous children despite the accessibility to a wide range of clinical treatments prescribed for retinopathy of prematurity. Apelin/APJ [class A (rhodopsin-like) G-protein-coupled receptor] signaling regulates retinopathy of prematurity augmented with uncontrolled angiogenesis. Antagonists targeting pathological apelin/APJ-signaling-induced angiogenesis could be effective in attenuating retinopathy of prematurity. The therapeutic proficiency of antagonists in diverse modalities: peptides, bioactive molecules and antibodies, targeting apelin peptides or the APJ receptor is discussed in this review. We hypothesize the antagonists could effectively attenuate the retinal vasculature triggered by apelin/APJ signaling activation governing vision impairment in young children.

Late Growth and Changes in Body Composition Influence Odds of Developing Retinopathy of Prematurity among Preterm Infants

Background: While postnatal growth in the first month of life is known to impact retinopathy of prematurity (ROP) risk, the impact of growth later in hospitalization, during critical times of retinal vascularization, remains unknown. The purpose of this study was to assess if postnatal growth and body composition during the second half of neonatal intensive care unit hospitalization were associated with severity of retinopathy of prematurity in very low birth weight preterm infants. Methods: Prospective observational pilot study of 83 infants born <32 weeks gestation and <1500 g, conducted at a Level IV neonatal intensive care unit. Body composition was measured during the second half of hospitalization. Infants were evaluated for retinopathy of prematurity. Logistic regression was performed. Results: Greater gains in fat mass, fat-free mass, and percent body fat from 32 to 37 weeks postmenstrual age and higher % body fat at term postmenstrual age were associated with decreased odds of ≥stage 2 retinopathy of prematurity (p < 0.05). Conclusions: Improved growth later in neonatal intensive care unit hospitalization and increased adiposity at term may reduce odds of severe retinopathy of prematurity.

Elabela and Apelin actions in healthy and pathological pregnancies

Pregnancy is a dynamic and precisely organized process during which one or more baby develops. Embryonic development relies on the formation of the placenta, allowing nutrient and oxygen exchange between the mother and the fetus. Dysfunction of placental formation lead to pregnancy disorders such as preeclampsia (PE) with serious deleterious consequences for fetal and maternal health. Identifying factors involved in fetoplacental homeostasis could inform better diagnostic and therapeutic strategies for these pathological pregnancies. Here, we summarize actions of elabela, apelin and their common receptor APJ in the fetoplacental unit. Studies indicate that elabela is crucial for embryo cardiovascular system formation and early placental development, while apelin acts in mid/late gestation to modulate fetal angiogenesis and energy homeostasis. Most of these findings, drawn from animal models, indicate a key role of elabela/apelin-APJ system in the fetoplacental unit. This review also provides an overview of clinical studies investigating elabela/apelin-APJ system in pathological complicated pregnancies such as PE and gestational diabetes mellitus (GDM). While elabela-deficient mice display all the features of PE, current clinical studies show no difference in circulating elabela levels between PE and control patients which does not support a role in PE development. Conversely, apelin levels are increased during PE, but the use of apelin as an early PE marker remains to be fully investigated.

The progress of prophylactic treatment in retinopathy of prematurity

Retinopathy of prematurity (ROP) is a retinal vascular disorder frequently found in premature infants. Different therapeutic strategies have been developed to treat ROP. However, there are still many children with ROP suffering by severe limitations in vision or even blindness. Recently, ROP has been suggested to be caused by abnormal development of the retinal vasculature, but not simply resulted by retinal neovascularization which takes about 4 to 6wk after birth in premature infants. Thus, instead of focusing on how to reduce retinal neovascularization, understanding the pathological changes and mechanisms that occur prior to retinal neovascularization is meaningful, which may lead to identify novel target(s) for the development of novel strategy to promote the healthy growth of retinal blood vessels rather than passively waiting for the appearance of retinal neovascularization and removing it by force. In this review, we discussed recent studies about, 1) the pathogenesis prior to retinal neovascularization in oxygen-induced retinopathy (OIR; a ROP in animal model) and in premature infants with ROP; 2) the preclinical and clinical research on preventive treatment of early OIR and ROP. We will not only highlight the importance of the mechanisms and signalling pathways in regulating early stage of ROP but also will provide guidance for actively exploring novel mechanisms and discovering novel treatments for early phase OIR and ROP prior to retinal neovascularization in the future.

Effects of apelin on retinal microglial cells in a rat model of oxygen-induced retinopathy of prematurity

This study explores the effects of apelin on retinal microglial cells in rat models of oxygen-induced retinopathy of prematurity (ROP). Totally, 274 rats were selected for establishing oxygen-induced retinopathy (OIR) models, and 92 healthy rats for control group. OIR rats were assigned into OIR, 10^-5  g/L apelin, 10^-4  g/L apelin, and 10^-3  g/L apelin groups. Immunohistochemistry was employed to determine morphology of microglial cells and cell number. CDllb, ionized calcium-binding adapter molecule 1 (IBA-1), TNF-α, and iNOS mRNA and protein expressions were identified using RT-qPCR and Western blotting, respectively. ELISA was employed to determine the levels of VEGF and glial fibrillary acidic protein (GFAP). The amoeboid microglial cells were found in the OIR and 10^-3  g/L apelin groups, while bipolar microglial cells were found in the normal control, 10^-5  g/L apelin and 10^-4  g/L apelin groups. In the 1, 2, 3, and 4th week after apelin treatment, there were significantly decreased bipolar microglial cells, lower mRNA and protein expressions of CDllb, IBA-1, TNF-α and iNOS, and the levels of VEGF and GFAP in the 10^-4  g/L apelin group than in the OIR, 10^-3  g/L apelin and 10^-5  g/L apelin groups. The differences between the normal control and 10^-4  g/L apelin groups are not significant. Compared with the OIR group, the 10^-5  g/L apelin and 10^-3  g/L apelin groups presented decreased microglial cells and mRNA and protein expressions of CDllb, IBA-1, TNF-α, and iNOS. Appropriate concentration of apelin may reduce retinal microglial cells in a rat model of oxygen-induced ROP.

Apelin/APJ signaling in hypoxia-related diseases

The regulatory peptide apelin is the endogenous ligand for the orphan G protein-coupled receptor APJ. Apelin and APJ exist in a variety of tissues, with special status in the heart, lung and tumors. Consequently, the apelin/APJ system exerts a broad range of activities that affect multiple organ systems. Accumulating evidence indicates that the expressions of apelin and APJ are significantly augmented by hypoxia through the hypoxia-inducible factor-1 alpha (HIF-1α) signaling pathway. Increased apelin promotes cellular proliferation, migration and survival, therefore regulating angiogenesis. In addition, the pre-administration of exogenous apelin is involved in the occurrence and development of hypoxia-induced pathological diseases. The purpose of this article is to review the properties of the apelin/APJ system, which is affected by hypoxic conditions, and the regulation of apelin/APJ signaling in hypoxia-associated disorders. Thus, the apelin/APJ system may be a potential therapeutic target in hypoxia-related diseases.

Serum erythropoietin, insulin-like growth factor 1, and vascular endothelial growth factor in etiopathogenesis of retinopathy of prematurity

BACKGROUND AND OBJECTIVE

The role of growth factors in the pathogenesis of retinopathy of prematurity (ROP) is known. To better understand this issue, the authors investigated vascular endothelial growth factor (VEGF), insulin-like growth factor 1 (IGF-1), and erythropoietin (EPO) levels in the cord blood of premature newborns.

PATIENTS AND METHODS

IGF-1, VEGF, and EPO levels were measured in cord blood samples obtained from 93 infants less than 32 weeks of gestational age at birth, and their predictive value in the development of ROP was investigated.

RESULTS

The mean birth age and mean birth weight were 32.2 ± 1.5 weeks and 1,678 ± 326 g, respectively, in infants without ROP and 29.6 ± 2.3 weeks and 1,384 ± 343 g, respectively, in infants with ROP. Multivariate logistic regression analysis showed that only the gestational age and the serum VEGF at birth were independently associated with the risk of developing ROP (P = .002, Exp[B] = 0.514, CI = 95%: 0.341-0.775; P = .028, Exp[B] = 0.999, CI = 95%: 0.997-1.00).

CONCLUSION

Serum VEGF levels at birth were lower in infants who later developed ROP. This may have a predictive value for ROP and contribute to the pathogenesis, because affected infants may be more susceptible to extrauterine hyperoxic insult.