Systemic Inflammation-Associated Proteins and Retinopathy of Prematurity in Infants Born Before the 28th Week of Gestation

Circulating VEGF-A Levels in Relation to Retinopathy of Prematurity and Treatment Effects: A Systematic Review and Meta-Analysis

Topic

Retinopathy of prematurity (ROP) is a severe retinal vascular disorder affecting preterm infants, potentially leading to retinal detachment and blindness. This review aims to elucidate the relationship between systemic VEGF levels and ROP.

Clinical Relevance

This systematic review aims to consolidate evidence from available studies to guide future research and inform clinical practice. In particular, the role of circulating VEGF-A levels in predicting ROP onset and progression, and evaluating the impact of anti-VEGF therapy on these levels, is crucial in ensuring efficacy and safety in patient care.

Methods

Scopus and PubMed were searched to identify studies investigating circulating VEGF-gene products in ROP patients using immunologic assays. Two authors independently screened the literature and extracted data, employing a random-effects meta-analysis to compare VEGF levels as the ratio of means between ROP patients and controls before and after treatment, heterogeneity was reported by I2-statistics. Risks of bias and publication bias were assessed using Quality Assessment of Diagnostic Accuracy Studies-2 and funnel plots/Egger's tests, respectively.

Results

Out of 941 papers, 54 were included, with 26 providing posttreatment data and 31 providing biomarker data. Findings show a significant decrease in VEGF-A levels in the first week after ROP treatment (ratio of means [95% confidence interval] 0.34 [0.25-0.45], I2 = 97%, 17 publications). Anti-VEGF therapy showed a significantly more pronounced decrease (0.31 [0.25-0.38], I2 = 40%, 7 publications) than laser treatment in the first week after treatment (0.77 [0.61-0.97], I2 = 42%, 2 publications, subgroup difference, P < 0.01), among studies with a low risk of bias. Serum samples demonstrated a more marked decrease in VEGF-A than plasma (subgroup difference P < 0.01). However, the use of blood VEGF-A concentration as a biomarker for ROP prediction has shown inconsistent trends. The risk of bias mainly stems from unclear patient selection and lack of sample timing or analytical method details.

Conclusion

While anti-VEGF treatment significantly reduced blood VEGF-A levels in the first week post-ROP treatment, blood VEGF-A levels did not consistently predict ROP development. Heterogeneity in the results underscores the need for optimized analytical methods and emphasizes the importance of considering individual variation in VEGF-A concentrations independent of ROP diagnosis.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

The relationship between inflammatory markers and retinopathy of prematurity in extremely premature infants

PURPOSE

This study aimed to evaluate the relationships among blood parameters, clinical factors, and retinopathy of prematurity (ROP) in extremely premature (EP) infants.

METHODS

This retrospective study included 153 EP infants who were categorized into two groups based on the presence of inflammatory diseases such as necrotizing enterocolitis, neonatal sepsis, bronchopulmonary dysplasia, severe intraventricular hemorrhage, preeclampsia, and premature rupture of membranes. Complete blood count parameters, neutrophil-lymphocyte ratio (NLR), lymphocyte-monocyte ratio, platelet-lymphocyte ratio (PLR), systemic inflammatory index, and platelet mass index were recorded during the first week and first month after birth. The study analyzed the impact of parameters obtained through blood tests during the first week and first month on the development of ROP and the requirement for treatment.

RESULTS

In this study, 96 infants were diagnosed with inflammatory diseases. After multivariate regression analyses, the duration of mechanical ventilation (p = 0.010) was found to be the only factor that led to ROP development. Moreover, lower gestational age (GA) (p = 0.006), higher NLR (p = 0.026), and lower PLR (p = 0.019) were observed in infants requiring treatment compared to infants with spontaneous resolution of ROP in this group. 57 infants did not have inflammatory diseases. Although the duration of mechanical ventilation (p = 0.041) and low levels of platelets (PLT) (p = 0.046) measured in the first month postnatally were significantly found to be associated with ROP developement, no parameter affecting the required treatment could be determined.

CONCLUSION

EP infants with longer mechanical ventilation durations and lower PLT counts are vulnerable to ROP development. GA, PLR, and NLR are predictive factors for treatment.

Novel Small Molecules with Anti-Inflammatory and Anti-Angiogenic Activity in a Mouse Model of Oxygen-Induced Retinopathy

Retinopathy of prematurity (ROP) has a dual-phase disease pathology; in phase 1, hyperoxia-induced vaso-obliteration occurs in the retinal vasculature due to increased oxidative stress (OS) and inflammation, followed by phase 2, where hypoxia increases the overproduction of growth factors, inducing retinal neovascularization. Toll-like receptor 2 and -4 (TLR2 and TLR4) overactivation, hyper-inflammation, macrophages, and neutrophil infiltration contribute to the developing ROP. AVR-121 and AVR-123 are novel classes of small-molecule dual inhibitors of TLR2/4 tested in a human leukemia monocytic cell line (THP-1) and cord-blood-derived mononuclear cells (CBMCs). Both compounds inhibited TLR2/4 signaling-related inflammatory cytokines in THP-1 cells and inhibited VEGF-induced neovascularization in human retinal endothelial cells (HRECs), which are hallmarks of ROP. In an oxygen-induced retinopathy (OIR) murine model, the intraperitoneal injection of AVR-123 in the hyperoxia phase (P7-P12) or a nanosuspension eyedrop of AVR-123 in the hypoxic phase (P12-P17) significantly reduced vaso-obliteration, angiogenesis, and inflammatory cytokine profiles while not inhibiting the necessary growth factor VEGF in the juvenile mouse eyes. The results are consistent with our hypothesis that targeting the dual TLR2/4 pathway will reduce inflammation, angiogenesis, and vaso-obliteration in vitro and in vivo and reduce cytotoxic immune cells. AVR-123 has the potential to be developed as a therapy for ROP.

Neonatal Sepsis Episodes and Retinopathy of Prematurity in Very Preterm Infants

Importance

Retinopathy of prematurity (ROP) is a major morbidity of preterm infants causing visual impairment, including blindness, for which timely treatment is vital and prevention is key. Increasing evidence suggests that exposure to neonatal sepsis contributes to ROP development.

Objective

To investigate the association between neonatal sepsis and ROP in 2 large-scale cohorts of preterm infants born at less than 29 weeks' gestation.

Design, Setting, and Participants

This retrospective cohort study was conducted using data from the German Neonatal Network (GNN) and Norwegian Neonatal Network (NNN). The GNN involves 68 and the NNN includes 21 level III neonatal intensive care units. Participants were infants born at a gestation of 22 weeks and 0 days to 28 weeks and 6 days and enrolled in the GNN between January 1, 2009, and December 31, 2022, and NNN between January 1, 2009, and December 31, 2018. Data were analyzed from February through September 2023.

Exposure

Single or multiple episodes of culture-proven sepsis.

Main Outcomes and Measures

Any ROP and treatment-warranted ROP.

Results

Among 12 794 infants in the GNN (6043 female [47.2%] and 6751 male [52.8%]; mean [SD] gestational age, 26.4 [1.5] weeks) and 1844 infants in the NNN (866 female [47.0%] and 978 male [53.0%]; mean [SD] gestational age, 25.6 [1.5] weeks), the mean (SD) birth weight was 848 (229) g and 807 (215) g, respectively. Any ROP was present in 6370 infants (49.8%) in GNN and 620 infants (33.6%) in NNN, and treatment-warranted ROP was present in 840 infants (6.6%) in GNN and 140 infants (7.6%) in NNN. In both cohorts, there were increasing rates of treatment-warranted ROP with each sepsis episode (no sepsis: 572 of 10 658 infants [5.4%] in GNN and 85 of 1492 infants (5.7%) in NNN; 1 episode: 190 of 1738 infants in GNN [10.9%] and 29 of 293 infants [9.9%] in NNN; 2 episodes: 53 of 314 infants in GNN [16.9%] and 13 of 49 infants [26.5%] in NNN; 3 episodes: 25 of 84 infants [29.8%] in GNN and 3 of 10 infants [30.0%] in NNN). After adjusting for multiple confounders in the GNN dataset, the number of sepsis episodes was associated with ROP and treatment-warranted ROP compared with 0 episodes (1 episode: adjusted odds ratio [aOR], 1.44 [95% CI, 1.27-1.63]; P < .001 and OR, 1.60 [95% CI, 1.31-1.96]; P < .001, respectively; 2 episodes: OR, 1.81 [95% CI, 1.35-2.42]; P < .001 and OR, 2.38 [95% CI, 1.68-3.37]; P < .001, respectively; 3 episodes: OR, 4.39 [95% CI, 2.19-8.78]; P < .001 and OR, 3.88 [95% CI, 2.29-6.55]; P < .001, respectively). These associations were confirmed for any ROP by propensity score matching (for example, the aOR with propensity score matching was 1.76 [95% CI, 1.54-2.02]; P < .001 for 1 episode vs 0 episodes and 1.58 [95% CI, 1.12-2.22]; P = .007 for 3 episodes vs 0 or 1 episode). In the NNN dataset, surgical NEC was associated with treatment-warranted ROP (multivariable analysis: aOR, 3.37 [95% CI, 1.78-6.37]; P < .001).

Conclusions and Relevance

This study found that in the large-scale GNN cohort, recurrent culture-proven sepsis was associated with ROP and treatment-warranted ROP in infants born at less than 29 weeks.

Retinopathy of prematurity and neurodevelopmental outcome and quality of life at 10 years of age

Objective

In a cohort of 10-year-old children born extremely preterm, we evaluated the hypothesis that increasing severity of retinopathy of prematurity (ROP) is associated with increasing frequency of unfavorable neurodevelopmental and quality of life outcomes.

Study Design

Study participants were classified according to the severity of ROP. At 10 years of age, their neurocognitive abilities, academic achievement, and gross motor function were assessed, and they were evaluated for autism spectrum disorder, anxiety, depression, and quality of life.

Results

After adjustment for sample attrition and confounders, only the association with lower quality of life persisted. Increasing severity of visual impairment was associated with worse neurodevelopmental outcomes and lower quality of life.

Conclusion

Among extremely preterm children, severity of visual impairment, but not severity of ROP, was associated with adverse neurodevelopmental outcomes at 10 years of age. Both severe ROP and more severe visual impairment were associated with lower quality of life.

Biomarkers in retinopathy of prematurity: a systematic review and meta-analysis

Aim

Retinopathy of prematurity is a significant global cause of childhood blindness. This study aims to identify serum biomarkers that are associated with the development of ROP.

Methods

A systematic review and meta-analysis was conducted using PRISMA guidelines. Three databases were searched (Pubmed, Scopus and Web of Science) from 2003 to March 2023. Only studies investigating serum biomarker levels in preterm infants (<37 weeks gestation) were included.

Results

Meta-analysis suggests that low serum IGF-1 levels have a strong association with the development of ROP [SMD (95% CI) of -.46 [-.63, -.30], p < .001]. Meta-analysis suggests that higher serum glucose levels were associated with the development of ROP [SMD (95% CI) of 1.25 [.94, 1.55], p < .001]. Meta-analysis suggests that thrombocytopenia is associated with the development of ROP [SMD (95% CI) of -.62 [-.86, -.37], p < .001].

Conclusion

Low levels of serum IGF-1, high levels of serum glucose and thrombocytopenia all appear to have the strongest association with the development of ROP out of the 63 biomarkers investigated in this review. These associations highlight their potential use as diagnostic biomarkers in ROP, though further research is needed to establish the exact relationship between these biomarkers and disease pathogenesis.

Genome-wide association identifies novel ROP risk loci in a multiethnic cohort

We conducted a genome-wide association study (GWAS) in a multiethnic cohort of 920 at-risk infants for retinopathy of prematurity (ROP), a major cause of childhood blindness, identifying 1 locus at genome-wide significance level (p < 5×10-8) and 9 with significance of p < 5×10-6 for ROP ≥ stage 3. The most significant locus, rs2058019, reached genome-wide significance within the full multiethnic cohort (p = 4.96×10-9); Hispanic and European Ancestry infants driving the association. The lead single nucleotide polymorphism (SNP) falls in an intronic region within the Glioma-associated oncogene family zinc finger 3 (GLI3) gene. Relevance for GLI3 and other top-associated genes to human ocular disease was substantiated through in-silico extension analyses, genetic risk score analysis and expression profiling in human donor eye tissues. Thus, we identify a novel locus at GLI3 with relevance to retinal biology, supporting genetic susceptibilities for ROP risk with possible variability by race and ethnicity.

Neonatal sepsis as a cause of retinopathy of prematurity: An etiological explanation

Retinopathy of prematurity (ROP) is a complex neonatal disorder with multiple contributing factors. In this paper we have mounted the evidence in support of the proposal that neonatal sepsis meets all requirements for being a cause of ROP (not a condition, mechanism, or even innocent bystander) by means of initiating the early stages of the pathomechanism of ROP occurrence, systemic inflammation. We use the model of etiological explanation, which distinguishes between two overlapping processes in ROP causation. It can be shown that sepsis can initiate the early stages of the pathomechanism via systemic inflammation (causation process) and that systemic inflammation can contribute to growth factor aberrations and the retinal characteristics of ROP (disease process). The combined contribution of these factors with immaturity at birth (as intrinsic risk modifier) and prenatal inflammation (as extrinsic facilitator) seems to provide a cogent functional framework of ROP occurrence. Finally, we apply the Bradford Hill heuristics to the available evidence. Taken together, the above suggests that neonatal sepsis is a causal inducer of ROP.

Systems levels analysis of lipid metabolism in oxygen-induced retinopathy

Hyperoxia induces glutamine-fueled anaplerosis in the Muller cells, endothelial cells, and retinal explants. Anaplerosis takes away glutamine from the biosynthetic pathway to the energy-producing TCA cycle. This process depletes biosynthetic precursors from newly proliferating endothelial cells. The induction of anaplerosis in the hyperoxic retina is a compensatory response, either to decreased glycolysis or decreased flux from glycolysis to the TCA cycle. We hypothesized that by providing substrates that feed into TCA, we could reverse or prevent glutamine-fueled anaplerosis, thereby abating the glutamine wastage for energy generation. Using an oxygen-induced retinopathy (OIR) mouse model, we first compared the difference in fatty acid metabolism between OIR-resistant BALB/cByJ and OIR susceptible C57BL/6J strains to understand if these strains exhibit metabolic difference that protects BALB/cByJ from the hyperoxic conditions and prevents their vasculature in oxygen-induced retinopathy model. Based on our findings from the metabolic comparison between two mouse strains, we hypothesized that the medium-chain fatty acid, octanoate, can feed into the TCA and serve as an alternative energy source in response to hyperoxia. Our systems levels analysis of OIR model shows that the medium chain fatty acid can serve as an alternative source to feed TCA. We here, for the first time, demonstrate that the retina can use medium-chain fatty acid octanoate to replenish TCA in normoxic and at a higher rate in hyperoxic conditions.

The effect of leucocytosis on retinopathy of prematurity

Postnatal leukocytosis reflects the general condition of inflammatory. Infection and inflammatory reaction have been proven to affect the occurrence of ROP and other visual dysfunction. Infants with a gestational age of < 28 weeks who were less than three days of age and admitted to the hospital between September 2015 and March 2021 were included in the study. Infants with a white blood cell (WBC) count ≥ 30 × 109/L were assigned to the leucocytosis group (n = 82). Gestational age- and weight-matched infants without leucocytosis were included as a control group (n = 85). The incidence and prognosis of ROP in preterm infants were compared between the groups. Receiver operating characteristic (ROC) curves were used to analyse the correlation between the WBC count and severe ROP. Compared to the infants in the control group, those in the leucocytosis group had lower 1-min Apgar scores (p < 0.001); higher C-reactive protein (p < 0.001) and procalcitonin (p < 0.001); and higher incidences of intracranial haemorrhage (p = 0.007), leukomalacia (p = 0.045), sepsis (p = 0.006), bronchopulmonary dysplasia (p = 0.017). The maternal age was higher in the leucocytosis group (p < 0.001). After adjusting for gestational age at 45 weeks, the incidence of severe ROP (p = 0.001) and the requirement for ranibizumab injections (p = 0.004) were higher in the leucocytosis group. The cut-off WBC count was determined to be 19.1 × 109/L, with a sensitivity of 88.6%, a specificity of 77.3%, and an area under the curve of 0.941 (95% confidence interval: 0.904-0.978) for the detection of severe ROP. Leucocytosis may be associated with severe ROP in premature infants.

Early detection and correlation of tear fluid inflammatory factors that influence angiogenesis in premature infants with and without retinopathy of prematurity

Purpose

To measure the levels of inflammatory factors in tear fluid of pre-term infants with and without retinopathy of prematurity (ROP).

Methods

The cross-sectional pilot study included 29 pre-term infants undergoing routine ROP screening. Pre-term infants were grouped as those without ROP (no ROP; n = 14) and with ROP (ROP; n = 15). Sterile Schirmer's strips were used to collect the tear fluid from pre-term infants. Inflammatory factors such as interleukin (IL)-6, IL-8, MCP1 (Monocyte Chemoattractant Protein 1; CCL2), RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted; CCL5), and soluble L-selectin (sL-selectin) were measured by cytometric bead array using a flow cytometer.

Results

Birth weight (BW) and gestation age (GA) were significantly (P < 0.05) lower in pre-term infants with ROP compared with those without ROP. Higher levels of RANTES (P < 0.05) and IL-8 (P = 0.09) were observed in the tear fluid of pre-term infants with ROP compared with those without ROP. Lower levels of tear fluid IL-6 (P = 0.14) and sL-selectin (P = 0.18) were measured in pre-term infants with ROP compared with those without ROP. IL-8 and RANTES were significantly (P < 0.05) higher in the tear fluid of pre-term infants with stage 3 ROP compared with those without ROP. Tear fluid RANTES level was observed to be inversely associated with GA and BW of pre-term infants with ROP and not in those without ROP. Furthermore, the area under the curve and odds ratio analysis demonstrated the relevance of RANTES/BW (AUC = 0.798; OR-7.2) and RANTES/MCP1 (AUC = 0.824; OR-6.8) ratios in ROP.

Conclusions

Distinct changes were observed in the levels of tear inflammatory factors in ROP infants. The status of RANTES in ROP suggests its possible role in pathobiology and warrants further mechanistic studies to harness it in ROP screening and management.

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.

Cord blood transforming growth factor-β-induced as predictive biomarker of retinopathy of prematurity in preterm infants

PURPOSE

To determine whether 14 inflammation-, angiogenesis-, and adhesion-related proteins in cord blood (CB), alone or in combination with conventional perinatal factors, could predict retinopathy of prematurity (ROP) in preterm infants.

METHODS

Data from 111 preterm infants (born at ≤ 32.0 weeks) were retrospectively reviewed. The levels of endoglin, E-selectin, HSP70, IGFBP-3/4, LBP, lipocaline-2, M-CSFR, MIP-1α, pentraxin 3, P-selectin, TGFBI, TGF-β1, and TNFR2 were assessed in stored CB samples collected at birth using ELISA kits. The primary endpoints included severe ROP (≥ stage 3) and type 1 ROP requiring treatment.

RESULTS

ROP was diagnosed in 29 infants (26.1%), among whom 14 (12.6%) had severe ROP and seven (6.3%) had type 1 ROP. Multivariate logistic regression showed that decreased CB TGFBI levels were significantly associated with severe ROP and type 1 ROP after adjusting for gestational age at birth. Stepwise regression analysis allowed to design prediction models with good accuracy, which comprised low CB TGFBI levels and low birth weight (BW) as predictors for severe ROP (area under the curve [AUC] = 0.888), and low CB endoglin levels and low BW as predictors for type 1 ROP (AUC = 0.950). None of the other CB proteins evaluated were found to be associated with severe ROP or type 1 ROP.

CONCLUSIONS

Low CB TGFBI levels are associated with severe ROP and type 1 ROP, independently of gestational age. Moreover, combined predictive models based on CB TGFBI and endoglin levels, along with BW data, may act as good indicators at birth for the neonatal risk of ROP progression.

Deficiency of hydrogen sulfide production and pregnancy rate in an experimental model: Association with preterm delivery

PROBLEM

Pro-inflammatory phenomena drive preterm delivery (PTD). Hydrogen sulfide is a gasotransmitter with anti-inflammatory properties produced through the activity of the enzyme cystathionine-γ-lyase (CSE), and its impact was studied in models of normal delivery and PTD in mice.

METHOD OF STUDY

Female CSE+/+ and CSE-/- mice were mated with male CSE+/+ mice; mating was done with drinking water unsupplemented and supplemented with cysteine. The pregnancy rate was monitored. PTD was induced by the intraperitoneal injection of bacterial lipopolysaccharide (LPS) on day 14.5 of pregnancy. Mice were sacrificed for tissue collection and splenocyte isolation after 6 and 12 h. Isolated splenocytes were stimulated for the production of tumor necrosis factor-alpha (TNFα), interleukin (IL)-10 and interferon-gamma (IFNγ); TNFα and vascular endothelial growth factor (VEGF) were measured in the fetuses and the placenta.

RESULTS

The successful pregnancy rate was lower in CSE-/- mice and it was restored with cysteine supplementation. CSE deficiency was associated with higher tissue concentrations of TNFα in the fetuses, attenuated IL-10 responses and higher IFNγ production from splenocytes. CSE deficiency was not associated with PTD. Following PTD induction, CSE-/- mice did not show attenuated IL-10 responses but the production of TNFα and IFNγ was lowered over-time; placental VEGF was also increased over-time.

CONCLUSIONS

CSE deficiency has an unfavorable impact on pregnancy. H2 S deficiency through CSE does not drive PTD but mediates pro-inflammatory phenomena in fetuses.

Using umbilical cord blood as a source of paediatric packed red blood cells: Processing and quality control

BACKGROUND AND OBJECTIVES

Umbilical cord blood (UCB) has been used as a source of red blood cells (RBCs) for neonatal/paediatric transfusion purposes. This study adopted two different procedures to obtain umbilical RBC (U-RBC) to compare its quality control parameters to those of fractionated adult RBC (A-RBC), for paediatric purposes.

MATERIALS AND METHODS

UCB units (24) were filtered and processed based on two different methods, namely, conventional/manual (P1;n12) and automatic (P2;n12). They were compared to five fractionated A-RBCs. U-RBC and A-RBC were stored for 14 days and had their haematological, biochemical, haemolytic and microbiological parameters analysed at D1, D7 and D14. Cytokines and growth factors (GFs) in residual U-RBC plasma were measured.

RESULTS

Mean volume of processed U-RBC units was 45 mL for P1 and 39 mL for P2; the mean haematocrit level reached 57% for P1 and 59% for P2. A-RBC recorded a mean volume of 44 mL. Haematologic and biochemical parameters analysed in U-RBC and A-RBC presented similar behaviours during storage time, except for parameter values, which differed between them. Pro-inflammatory and immunomodulatory cytokines, as well as GFs, were higher in U-RBC residual plasma than in that A-RBC.

CONCLUSION

UCB can be processed into RBC based on either manual or automated protocols. U-RBC units met the referenced quality parameters defined for A-RBC. Some features, mainly the biochemical ones, should be further investigated to help improve quality parameters, with emphasis on differences found in, and particularities of, this material and on recipients of this new transfusion practice.

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..

A Prospective Analysis of the Retinopathy of Prematurity Correlated with the Inflammatory Status of the Extremely Premature and Very Premature Neonates

Retinopathy of Prematurity (ROP) is a major cause of blindness in premature infants. This study aimed to evaluate the association between inflammatory markers and ROP development in extremely premature and very premature neonates and identify potential inflammatory biomarkers for ROP risk prediction. This prospective study was conducted from January 2021 to January 2023 in two clinical hospitals associated with the "Victor Babes" University of Medicine and Pharmacy Timisoara. The study population comprised neonates with a gestational age of less than 32 weeks. Various inflammatory markers, including total white blood cell count, polymorphonuclear leukocytes, C-reactive protein, interleukin-6, and lactate dehydrogenase, were analyzed from blood samples collected at birth and three days postnatally. ROP was diagnosed and classified following the International Classification of Retinopathy of Prematurity. The study included 48 neonates, 12 Extremely Premature Infants (EPI), and 36 Very Premature Infants (VPI). The EPI group had significantly higher mean interleukin-6 and lactate dehydrogenase levels at birth and three days postnatally than the VPI group. C-reactive protein levels at three days were significantly higher in the VPI group. Umbilical cord inflammation and ROP severity were found to have a statistically significant positive correlation. Half of the EPIs had moderate to severe ROP, significantly more than in the VPI group. The duration of oxygen supplementation, mechanical ventilation, Continuous Positive Airway Pressure (CPAP), gestational age less than 28 weeks, and umbilical cord inflammation at or above stage 3 were significant risk factors for developing ROP stage 2 or above. Elevated CRP and IL-6 were also significantly associated with an increased risk of developing ROP stage 2 or above, highlighting their potential as biomarkers for ROP risk prediction. This study suggests a significant association between inflammatory markers and ROP development in extremely premature and very premature neonates. These findings could contribute to the identification of potential inflammatory biomarkers for ROP risk prediction, improving early diagnosis and intervention strategies for this condition.

Association of inflammatory and angiogenic biomarkers in maternal plasma with retinopathy of prematurity in preterm infants

OBJECTIVE

To investigate whether various novel inflammatory and angiogenic biomarkers in maternal plasma, alone or in combination with baseline antenatal factors, could predict retinopathy of prematurity (ROP) in preterm infants.

METHODS

A retrospective cohort study was conducted on 140 premature singleton neonates born to women with preterm birth (≤32 weeks) and screened for ROP. Maternal blood obtained at the time of admission was assayed for CRP, endoglin, endostatin, IGFBP-2, IGFBP-3, IL-6, LBP, MMP-8, PlGF, S100A8/A9, TGFBI, and VEGFR-1. The primary outcome measures included severe ROP (stage 3 or higher) and type 1 ROP requiring treatment.

RESULTS

ROP was present in 25.7% (36/140) of the study population, including 20 (14.3%) cases of severe ROP and 14 (10%) with type 1 ROP. Multiple logistic regression analyses revealed significant associations between high concentrations of maternal plasma LBP and severe ROP, and between elevated plasma IL-6 and LBP levels and type 1 ROP (all P < 0.05), while adjusting for confounders (i.e., gestational age [GA] at sampling). Prenatal prediction models for severe ROP and type 1 ROP were developed by combining plasma IL-6 or LBP levels with GA at sampling, which showed good discriminatory power (area under the curve = 0.747 and 0.854, respectively).

CONCLUSIONS

IL-6 and LBP in maternal plasma were found to be independently associated with severe ROP and type 1 ROP. Prediction models based on these biomarkers along with GA at sampling may serve as good prenatal indicators for the neonatal risk of ROP progression in women at risk of preterm birth.

Progressive inflammation reduces high-frequency EEG activity and cortical dendritic arborisation in late gestation fetal sheep

BACKGROUND

Antenatal infection/inflammation is associated with disturbances in neuronal connectivity, impaired cortical growth and poor neurodevelopmental outcomes. The pathophysiological substrate that underpins these changes is poorly understood. We tested the hypothesis that progressive inflammation in late gestation fetal sheep would alter cortical neuronal microstructure and neural function assessed using electroencephalogram band power analysis.

METHODS

Fetal sheep (0.85 of gestation) were surgically instrumented for continuous electroencephalogram (EEG) recording and randomly assigned to repeated saline (control; n = 9) or LPS (0 h = 300 ng, 24 h = 600 ng, 48 h = 1200 ng; n = 8) infusions to induce inflammation. Sheep were euthanised 4 days after the first LPS infusion for assessment of inflammatory gene expression, histopathology and neuronal dendritic morphology in the somatosensory cortex.

RESULTS

LPS infusions increased delta power between 8 and 50 h, with reduced beta power from 18 to 96 h (P < 0.05 vs. control). Basal dendritic length, numbers of dendritic terminals, dendritic arborisation and numbers of dendritic spines were reduced in LPS-exposed fetuses (P < 0.05 vs. control) within the somatosensory cortex. Numbers of microglia and interleukin (IL)-1β immunoreactivity were increased in LPS-exposed fetuses compared with controls (P < 0.05). There were no differences in total numbers of cortical NeuN + neurons or cortical area between the groups.

CONCLUSIONS

Exposure to antenatal infection/inflammation was associated with impaired dendritic arborisation, spine number and loss of high-frequency EEG activity, despite normal numbers of neurons, that may contribute to disturbed cortical development and connectivity.

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.

Retinopathy of prematurity and neurodevelopmental outcomes in preterm infants: A systematic review and meta-analysis

Background

Retinopathy of prematurity (ROP) and abnormal brain development share similar risk factors and mechanisms. There has been contrasting evidence on the association of ROP with adverse neurodevelopmental outcomes.

Objective

We analysed the association between ROP at levels of severity and treatment with all neurodevelopmental outcomes until adolescence.

Data source

We followed PRISMA guidelines and searched Medline and Embase between 1 August 1990 and 31 March 2022.

Study selection and participants

Randomised or quasi-randomised clinical trials and observational studies on preterm infants (<37 weeks) with ROP [type 1 or severe ROP, type 2 or milder ROP, laser or anti-vascular endothelial growth factor (VEGF) treated] were included.

Data extraction and synthesis

We included studies on ROP and any neurocognitive or neuropsychiatric outcomes.

Outcomes

The primary outcomes were as follows: cognitive composite scores evaluated between the ages of 18 and 48 months by the Bayley Scales of Infant and Toddler Development (BSID) or equivalent; neurodevelopmental impairment (NDI; moderate to severe NDI or severe NDI), cerebral palsy, cognitive impairment; and neuropsychiatric or behavioural problems. The secondary outcomes were as follows: motor and language composite scores evaluated between the ages of 18 and 48 months by BSID or equivalent; motor/language impairment; and moderate/severe NDI as defined by the authors.

Results

In preterm infants, "any ROP" was associated with an increased risk of cognitive impairment or intellectual disability [n = 83,506; odds ratio (OR): 2.56; 95% CI: 1.40-4.69; p = 0.002], cerebral palsy (n = 3,706; OR: 2.26; 95% CI: 1.72-2.96; p < 0.001), behavioural problems (n = 81,439; OR: 2.45; 95% CI: 1.03-5.83; p = 0.04), or NDI as defined by authors (n = 1,930; OR: 3.83; 95% CI: 1.61-9.12; p = 0.002). Type 1 or severe ROP increased the risk of cerebral palsy (OR: 2.19; 95% CI: 1.23-3.88; p = 0.07), cognitive impairment or intellectual disability (n = 5,167; OR: 3.56; 95% CI: 2.6-4.86; p < 0.001), and behavioural problems (n = 5,500; OR: 2.76; 95% CI: 2.11-3.60; p < 0.001) more than type 2 ROP at 18-24 months. Infants treated with anti-VEGF had higher odds of moderate cognitive impairment than the laser surgery group if adjusted data (gestational age, sex severe intraventricular haemorrhage, bronchopulmonary dysplasia, sepsis, surgical necrotising enterocolitis, and maternal education) were analysed [adjusted OR (aOR): 1.93; 95% CI: 1.23-3.03; p = 0.04], but not for cerebral palsy (aOR: 1.29; 95% CI: 0.65-2.56; p = 0.45). All outcomes were adjudged with a "very low" certainty of evidence.

Conclusion and relevance

Infants with "any ROP" had higher risks of cognitive impairment or intellectual disability, cerebral palsy, and behavioural problems. Anti-VEGF treatment increased the risk of moderate cognitive impairment. These results support the association of ROP and anti-VEGF treatment with adverse neurodevelopmental outcomes.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022326009.

Retinopathy of prematurity

Retinopathy of prematurity (ROP) is a devastating neurovascular disease of the retina in newborn infants that can lead to vision deficits or even blindness. In this concise review we discuss our current knowledge about diagnosis, etiology, pathogenesis, intervention, and outcomes of the disease. Major advancements have been made both in categorizing the disease in the new International Classification of Retinopathy of Prematurity, Third Edition classification and in treating severe ROP with anti-vascular endothelial growth factor (VEGF) agents. New development always creates new questions and opens up new areas of research. We will discuss in this review both the benefits and downsides of the new anti-VEGF treatment approaches in ROP, especially in light of our improved understanding of the underlying ROP pathophysiology. We also offer pointers to areas where more research is needed.

Maternal siRNA silencing of placental SAA2 mitigates preterm birth following intrauterine inflammation

The placental inflammatory processes induced maternally result in preterm birth (PTB). Serum amyloid A (SAA) is a well-known biomarker of inflammation. The objective of this study was to investigate whether murine placental SAA isoforms (SAA1–4) participate in the mechanism of spontaneous PTB and whether maternal regulation of SAA production may serve as a therapeutic approach. During the gestation, all isoforms of SAA were detectable except SAA2. The mouse model of intrauterine inflammation was established using LPS infusion to the uterus. Following intrauterine inflammation, placental SAA2 increased significantly. Inhibition of Saa2, using siSaa2, markedly decreased PTB. The increased placental expression of pro-inflammatory cytokines Il1β, Il6, and Tnfα were downregulated by siSaa2 treatment. Maternal inhibition of Saa2 did not change the expression of Saa1–4 in the fetal brain. Explant inflammatory culture of placentas with siSaa2 showed similar results to our in vivo experiments. This study demonstrates the highly expressed placental SAA2 as a novel therapeutic target, and maternal administration of siRNA as a promising approach to alleviate PTB.

Modification of erythrocyte membrane phospholipid composition in preterm newborns with retinopathy of prematurity: The omegaROP study

N-3 polyunsaturated fatty acids (PUFAs) may prevent retinal vascular abnormalities observed in oxygen-induced retinopathy, a model of retinopathy of prematurity (ROP). In the OmegaROP prospective cohort study, we showed that preterm infants who will develop ROP accumulate the n-6 PUFA arachidonic acid (ARA) at the expense of the n-3 PUFA docosahexaenoic acid (DHA) in erythrocytes with advancing gestational age (GA). As mice lacking plasmalogens -That are specific phospholipids considered as reservoirs of n-6 and n-3 PUFAs- Display a ROP-like phenotype, the aim of this study was to determine whether plasmalogens are responsible for the changes observed in subjects from the OmegaROP study. Accordingly, preterm infants aged less than 29 weeks GA were recruited at birth in the Neonatal Intensive Care Unit of University Hospital Dijon, France. Blood was sampled very early after birth to avoid any nutritional influence on its lipid composition. The lipid composition of erythrocytes and the structure of phospholipids including plasmalogens were determined by global lipidomics using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). LC-HRMS data confirmed our previous observations by showing a negative association between the erythrocyte content in phospholipid esterified to n-6 PUFAs and GA in infants without ROP (rho = -0.485, p = 0.013 and rho = -0.477, p = 0.015 for ethanolamine and choline total phospholipids, respectively). Phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) species with ARA, namely PtdCho16:0/20:4 (rho = -0.511, p < 0.01) and PtdEtn18:1/20:4 (rho = -0.479, p = 0.015), were the major contributors to the relationship observed. On the contrary, preterm infants developing ROP displayed negative association between PtdEtn species with n-3 PUFAs and GA (rho = -0.380, p = 0.034). They were also characterized by a positive association between GA and the ratio of ethanolamine plasmalogens (PlsEtn) with n-6 PUFA to PlsEtn with n-3 PUFAs (rho = 0.420, p = 0.029), as well as the ratio of PlsEtn with ARA to PlsEtn with DHA (rho = 0.843, p = 0.011). Altogether, these data confirm the potential accumulation of n-6 PUFAs with advancing GA in erythrocytes of infants developing ROP. These changes may be partly due to plasmalogens.

Paclitaxel and Urolithin A Prevent Histamine-Induced Neurovascular Breakdown Alike, in an Ex Vivo Rat Eye Model

Neurovascular eye problems are better prevented than managed or treated. Despite growing concern of occurrence in aging populations and development secondary to diseases such as diabetes and hypertension, we currently have very few options to tackle this global problem. Creating effective and high-throughput screening strategies is as important as the intervention itself. Here, we present for the first time a robust ex vivo rat eye model of histamine-induced vascular damage for investigating the therapeutic potential of paclitaxel (PTX) and urolithin A (UA) as alternatives to dexamethasone for preventing vascular damage in the retina. Extensive loss of vascularization and apoptosis were observed in the histamine-challenged group and successfully prevented in the intervention groups, more significantly in the PTX and UA. These important early results indicate that PTX and UA could be developed as potential preventive strategies for a wide variety of retinal diseases.

The association between amniotic fluid-derived inflammatory mediators and the risk of retinopathy of prematurity

Prenatal and perinatal infections and inflammation appear to associated with the development of retinopathy of prematurity (ROP). In this study, we evaluated whether inflammatory mediators in amniotic fluid (AF) retrieved during cesarean delivery influence the development of ROP in very low birth weight (VLBW) infants. This retrospective study included 16 and 32 VLBW infants who did and did not develop any stage of ROP, respectively. Each infant with ROP was matched with 2 infants without ROP based on days of ventilation care, gestational age, and birth weight. AF was obtained during cesarean delivery, and the levels of intra-amniotic inflammatory mediators such as interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, matrix metalloproteinase (MMP)-2, MMP-8, MMP-9, and tumor necrosis factor (TNF)-α were measured using a Human Magnetic Luminex assay (R&D Systems, Minneapolis, MN). The differences in the levels of inflammatory mediators according to the presence or absence of ROP were compared. In patients who developed ROP, the level of MMP-2 in the AF was significantly increased (P = .011), whereas the levels of IL-10 and TNF-α were significantly decreased (P = .028 and .046, respectively) compared with those in infants who did not develop ROP. The levels of the other mediators were not significantly different between the 2 groups. Multivariate regression analysis showed that MMP-2 was a risk factor for the development of ROP (odds ratio, 2.445; 95% confidence interval, 1.170-5.106; P = .017). The concentration of MMP-2 in AF is an independent factor in the development of ROP. Further studies are needed to determine whether the levels of inflammatory mediators in AF affect the ROP severity.

Neurosensory Alterations in Retinopathy of Prematurity: A Window to Neurological Impairments Associated to Preterm Birth

Retinopathy of prematurity (ROP) is one of the main blinding diseases affecting preterm newborns and is classically considered a vascular disorder. The premature exposure to the extrauterine environment, which is hyperoxic in respect to the intrauterine environment, triggers a cascade of events leading to retinal ischemia which, in turn, makes the retina hypoxic thus setting off angiogenic processes. However, many children with a history of ROP show persistent vision impairment, and there is evidence of an association between ROP and neurosensory disabilities. This is not surprising given the strict relationship between neuronal function and an adequate blood supply. In the present work, we revised literature data evidencing to what extent ROP can be considered a neurodegenerative disease, also taking advantage from data obtained in preclinical models of ROP. The involvement of different retinal cell populations in triggering the neuronal damage in ROP was described along with the neurological outcomes associated to ROP. The situation of ROP in Italy was assessed as well.

Retinopathy of prematurity: contribution of inflammatory and genetic factors

Retinopathy of prematurity (ROP) is a retinal vasoproliferative disorder that represents an important cause of childhood visual impairment and blindness. Although oxidative stress has long been implicated in ROP etiology, other prenatal and perinatal factors are also involved. This review focuses on current research involving inflammation and genetic factors in the pathogenesis of ROP. Increasing evidence suggests that perinatal inflammation or infection contributes to ROP pathogenesis. Cytokines and chemokines with a fundamental role in inflammatory responses and that significantly contributing to angiogenesis are analyzed. Microglia cells, the retinal-resident macrophages, are crucial for retinal homeostasis, however, under sustained pathological stimuli release exaggerated amounts of inflammatory mediators and can promote pathological neovascularization. Current modulation of angiogenic cytokines, such as treatment with antibodies to vascular endothelial growth factor (anti-VEGF), has shown efficacy in the treatment of ocular neovascularization; however, some patients are refractory to anti-VEGF agents, suggesting that other angiogenic or anti-angiogenic cytokines need to be identified. Much evidence suggests that genetic factors contribute to the phenotypic variability of ROP. Several studies have implicated the involvement of candidate genes from different signaling pathways in the development of ROP. However, a genetic component with a major impact on ROP has not yet been discovered. Most studies have limitations and did not replicate results. Future research involving bioinformatics, genomics, and proteomics may contribute to finding more genes associated with ROP and may allow discovering better solutions in the management and treatment of ROP.

Novel Potential Biomarkers for Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is the main risk factor for vision-threatening disease in premature infants with low birth weight. An accumulating number of independent studies have focused on ROP pathogenesis and have demonstrated that laser photocoagulation therapy and/or anti-VEGF treatment are effective. However, early diagnosis of ROP is still critical. At present, the main method of ROP screening is based on binocular indirect ophthalmoscopy. However, the judgment of whether ROP occurs and whether treatment is necessary depends largely on ophthalmologists with a great deal of experience. Therefore, it is essential to develop a simple, accurate and effective diagnostic method. This review describes recent findings on novel biomarkers for the prediction, diagnosis and prognosis of ROP patients. The novel biomarkers were separated into the following categories: metabolites, cytokines and growth factors, non-coding RNAs, iconography, gut microbiota, oxidative stress biomarkers, and others. Biomarkers with high sensitivity and specificity are urgently needed for the clinical applications of ROP. In addition, using non-invasive or minimally invasive methods to obtain samples is also important. Our review provides an overview of potential biomarkers of ROP.

Extreme prematurity: Risk and resiliency

Individuals born extremely preterm (before 28 weeks of gestation) comprise only about 0.7% of births in the United States and an even lower proportion in other high resource countries. However, these individuals account for a disproportionate number of children with cerebral palsy, intellectual deficit, autism spectrum disorder, attention deficit hyperactivity disorder, and epilepsy. This review describes two large multiple center cohorts comprised of individuals born extremely preterm: the EPICURE cohort, recruited 1995 in the United Kingdom and the Republic of Ireland, and the Extremely Low Gestational Age Newborn (ELGAN), recruited 2002-2004 in five states in the United States. The primary focus of these studies has been neurodevelopmental disorders, but also of interest are growth, respiratory illness, and parent- and self-reported global health and well-being. Both of these studies indicate that among individuals born extremely preterm the risks of most neurodevelopmental disorders are increased. Early life factors that contribute to this risk include perinatal brain damage, some of which can be identified using neonatal head ultrasound, bronchopulmonary dysplasia, and neonatal systemic inflammation. Prenatal factors, particularly the family's socioeconomic position, also appear to contribute to risk. For most adverse outcomes, the risk is higher in males. Young adults born extremely preterm who have neurodevelopmental impairment, as compared to those without such impairment, rate their quality of life lower. However, young adults born extremely preterm who do not have neurodevelopmental impairments rate their quality of life as being similar to that of young adults born at term. Finally, we summarize the current state of interventions designed to improve the life course of extremely premature infants, with particular focus on efforts to prevent premature birth and on postnatal efforts to prevent adverse neurodevelopmental outcomes.

Beyond Fetal Immunity: A Systematic Review and Meta-Analysis of the Association Between Antenatal Corticosteroids and Retinopathy of Prematurity

Background: Retinopathy of prematurity (ROP) is a major cause of childhood blindness. Antenatal corticosteroids (ACS) exposure is known to ameliorate the risk of and mortality of neonatal morbidities. However, the effect of ACS on ROP development is currently unknown. We conducted a meta-analysis with up-to-date evidence to assess the association between ACS exposure and the development of ROP in at-risk preterm infants.

Methods: PubMed, EMBASE, Scopus, Web of Science, and the Cochrane Library were systematically searched from inception to May 2021, supplemented with manual search from reference lists. Studies with a control group reporting ROP rate in ACS-exposed infants were included. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated utilizing a random-effects model. The Newcastle-Ottawa Scale was used for assessment of risk of bias in the included studies. Meta-regressions were performed to explore the predictive role of confounders for between-study variance.

Results: A total of 63 studies, involving 196,264 infants, were included. Meta-analysis showed ACS exposure was not associated with ROP occurrence (uOR 0.92, 95% CI 0.80–1.07; aOR 0.87, 95% CI 0.7–1.08). Results from extremely immature subgroups revealed significant reduced risks of ROP occurrence in ACS-exposed infants. ACS exposure was associated with significantly lower odds of ROP progression in adjusted analysis (aOR 0.48, 95% CI 0.26–0.89) instead of unadjusted analysis (uOR 0.86, 95% CI 0.68–1.08). Meta-regression showed birth weight and patent ductus arteriosus of the cohort were associated with ROP occurrence, sample size and study design strongly associated with ROP progression in ACS-exposed infants.

Conclusion: ACS treatment may decrease, but not prevent, the severity of ROP. Findings from severe ROP should be interpreted with caution owing to limited studies and the possibility of false-positive results. Considering the particular benefits in extremely immature infants, we recommend routine usage of ACS in mothers with threatened delivery to this particular birth cohort to prevent ROP occurrence. Future studies adjusting for major confounders are warranted to mitigate risk of bias in such observational evidence.

Visuopathy of prematurity: is retinopathy just the tip of the iceberg?

Research on retinopathy of prematurity (ROP) focuses mainly on the abnormal vascularization patterns that are directly visible for ophthalmologists. However, recent findings indicate that children born prematurely also exhibit changes in the retinal cellular architecture and along the dorsal visual stream, such as structural changes between and within cortical areas. Moreover, perinatal sustained systemic inflammation (SSI) is associated with an increased risk for ROP and the visual deficits that follow. In this paper, we propose that ROP might just be the tip of an iceberg we call visuopathy of prematurity (VOP). The VOP paradigm comprises abnormal vascularization of the retina, alterations in retinal cellular architecture, choroidal degeneration, and abnormalities in the visual pathway, including cortical areas. Furthermore, VOP itself might influence the developmental trajectories of cerebral structures and functions deemed responsible for visual processing, thereby explaining visual deficits among children born preterm.

VEGFR1 signaling in retinal angiogenesis and microinflammation

Five vascular endothelial growth factor receptor (VEGFR) ligands (VEGF-A, -B, -C, -D, and placental growth factor [PlGF]) constitute the VEGF family. VEGF-A binds VEGF receptors 1 and 2 (VEGFR1/2), whereas VEGF-B and PlGF only bind VEGFR1. Although much research has been conducted on VEGFR2 to elucidate its key role in retinal diseases, recent efforts have shown the importance and involvement of VEGFR1 and its family of ligands in angiogenesis, vascular permeability, and microinflammatory cascades within the retina. Expression of VEGFR1 depends on the microenvironment, is differentially regulated under hypoxic and inflammatory conditions, and it has been detected in retinal and choroidal endothelial cells, pericytes, retinal and choroidal mononuclear phagocytes (including microglia), Müller cells, photoreceptor cells, and the retinal pigment epithelium. Whilst the VEGF-A decoy function of VEGFR1 is well established, consequences of its direct signaling are less clear. VEGFR1 activation can affect vascular permeability and induce macrophage and microglia production of proinflammatory and proangiogenic mediators. However the ability of the VEGFR1 ligands (VEGF-A, PlGF, and VEGF-B) to compete against each other for receptor binding and to heterodimerize complicates our understanding of the relative contribution of VEGFR1 signaling alone toward the pathologic processes seen in diabetic retinopathy, retinal vascular occlusions, retinopathy of prematurity, and age-related macular degeneration. Clinically, anti-VEGF drugs have proven transformational in these pathologies and their impact on modulation of VEGFR1 signaling is still an opportunity-rich field for further research.

The prenatal phase of retinopathy of prematurity

AIM

To explore the current literature on prenatal inflammation-associated risk factors for retinopathy of prematurity (ROP).

METHODS

Subjective summary of selected experimental and epidemiological publications that support the authors' central hypothesis that the aetiology of ROP begins before birth.

RESULTS

Based on current evidence we suggest that, contrary to current aetiological models, the process of ROP development begins with a prephase in utero. This beginning is likely initiated by inflammatory responses that are associated with intrauterine infection.

CONCLUSION

We propose a novel aetio-pathogenetic model of ROP and suggest that the effects of postnatal exposure to inflammatory stressors (resulting from infection or hyperoxia or both) as well as those of other pre- and postnatal contributors to the complex pathogenesis of ROP might be modified by the prenatal phase of the disease.

The immunological link between neonatal lung and eye disease

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are two neonatal diseases of major clinical importance, arising in large part as a consequence of supplemental oxygen therapy used to promote the survival of preterm infants. The presence of coincident inflammation in the lungs and eyes of neonates receiving oxygen therapy indicates that a dysregulated immune response serves as a potential common pathogenic factor for both diseases. This review examines the current state of knowledge of immunological dysregulation in BPD and ROP, identifying similarities in the cellular subsets and inflammatory cytokines that are found in the alveoli and retina during the active phase of these diseases, indicating possible mechanistic overlap. In addition, we highlight gaps in the understanding of whether these responses emerge independently in the lung and retina as a consequence of oxygen exposure or arise because of inflammatory spill-over from the lung. As BPD and ROP are anatomically distinct, they are often considered discreet disease entities and are therefore treated separately. We propose that an improved understanding of the relationship between BPD and ROP is key to the identification of novel therapeutic targets to treat or prevent both conditions simultaneously.

Retinopathy prematurity: a systematic review and meta-analysis study based on neonatal and maternal risk factors

BACKGROUND

Retinopathy of prematurity is the abnormal development of retinal arteries in preterm neonates less than 32 weeks and weighing 1500 g, and less, which can lead to visual impairment during life and blindness. This study aims to investigate the relationship between some clinical characteristics of neonates and mothers with Retinopathy of prematurity in the world via a systematic review and meta-analysis.

MATERIALS AND METHODS

The present study is a systematic review and meta-analysis on the relationship between maternal and neonatal clinical variables with Retinopathy of prematurity in the world from the beginning of 2000 to the end of 2020. Accordingly, all English articles published on the topic were searched in scientific databases of Web of Science, PubMed, Google Scholar, Science Direct, and Scopus. The articles were searched independently by two researchers. Statistical analysis of data was performed using fixed and random effects model statistical tests in the meta-analysis, Cochran, meta-regression, I² index, Funnel plot, and Begg's by STATA software program, version 14.

RESULT

A total of 191 studies with a sample size of 140,921 persons were including in the meta-analysis. Accordingly, Preterm delivery ≤28 weeks (OR:6.3, 95% CI:4.9-8.1), Birth Weight ≤1000 g (OR:5.8, 95% CI:4.8-6.8), Birth Weight ≤1500 g (OR:4.8, 95% CI:3.8-6.1), PROM (OR:1.2, 95% CI:1.0-1.4), induced fertility (OR:1.9, 95% CI:1.1-3.0) and Chorioamnionitis (OR:1.5, 95% CI:1.0-2.2) There was a statistically significant association with retinopathy.

CONCLUSION

Based on the results of the present meta-analysis, the risk of retinopathy of prematurity in neonates born at 28 weeks and less, LBW (weight 1500 g and less), neonatal hypotension, chorioamnionitis, and induced fertility increases.

Perinatal Inflammation: Could Partial Blocking of Cell Adhesion Molecule Function Be a Solution?

In spite of the great advances made in recent years in prenatal and perinatal medicine, inflammation can still frequently result in injury to vital organs and often constitutes a major cause of morbidity. It is today well established that in neonates—though vulnerability to infection among neonates is triggered by functional impairments in leukocyte adhesion—the decreased expression of cell adhesion molecules also decreases the inflammatory response. It is also clear that the cell adhesion molecules, namely, the integrins, selectins, and the immunoglobulin (Ig) gene super family, all play a crucial role in the inflammatory cascade. Thus, by consolidating our knowledge concerning the actions of these vital cell adhesion molecules during the prenatal period as well as regarding the genetic deficiencies of these molecules, notably leukocyte adhesion deficiency (LAD) I, II, and III, which can provoke severe clinical symptoms throughout the first year of life, it is anticipated that intervention involving blocking the function of cell adhesion molecules in neonatal leukocytes has the potential to constitute an effective therapeutic approach for inflammation. A promising perspective is the potential use of antibody therapy in preterm and term infants with perinatal inflammation and infection focusing on cases in which LAD is involved, while a further important scientific advance related to this issue could be the combination of small peptides aimed at the inhibition of cellular adhesion.

Stable incidence but regional differences in retinopathy of prematurity in Norway from 2009 to 2017

PURPOSE

To explore the changes over time and regional differences in the incidence of retinopathy of prematurity (ROP) in a national cohort of infants born <28 weeks' gestational age (GA).

METHODS

A population-based study of infants with GA <28 weeks in Norway from 2009 to 2017. Prospectively collected data on clinical variables and outcomes were obtained from the Norwegian Neonatal Network.

RESULTS

Of 1499 live-born infants transferred to a neonatal intensive care unit, 1156 were discharged alive. Four-hundred and fifty-eight infants (39.6%) had ROP, 152 (13.1%) had severe ROP, and 110 (9.5%) were treated for ROP. Eleven hundred infants (95.2%) had complete data sets. In a model comprising region of primary care, GA [odds ratios (OR): 0.65; 95% CI: 0.55-0.77], growth velocity (OR: 1.10; 95% CI: 1.00-2.00), medically treated patent ductus arteriosus (OR: 1.80; 95% CI: 1.19-2.72), weeks of supplemental oxygen (OR: 1.07; 95% CI: 1.03 to 1.11) and region of primary care (OR: 4.95; 95% CI: 3.05-8.04 for the pair of regions with the highest estimated OR) were significantly associated with severe ROP. Additionally, institutional differences for severe ROP were found, with ORs from 0.41 (95% CI: 0.05-3.23) to 5.36 (95% CI: 3.05-9.43) using the largest institution as reference. Incidences were stable over time after adjusting for GA. A larger proportion was treated with anti-vascular endothelial growth factor after 2011.

CONCLUSIONS

The incidence of severe ROP was stable between 2009 and 2017 in Norway. Regional and institutional differences need to be explored in future studies.

Long-term coordinated microstructural disruptions of the developing neocortex and subcortical white matter after early postnatal systemic inflammation

Severe postnatal systemic infection is highly associated with persistent disturbances in brain development and neurobehavioral outcomes in survivors of preterm birth. However, the contribution of less severe but prolonged postnatal infection and inflammation to such disturbances is unclear. Further, the ability of modern imaging techniques to detect the underlying changes in cellular microstructure of the brain in these infants remains to be validated. We used high-field ex-vivo MRI, neurohistopathology, and behavioral tests in newborn rats to demonstrate that prolonged postnatal systemic inflammation causes subtle, persisting disturbances in brain development, with neurodevelopmental delays and mild motor impairments. Diffusion-tensor MRI and neurite orientation dispersion and density imaging (NODDI) revealed delayed maturation of neocortical and subcortical white matter microstructure. Analysis of pyramidal neurons showed that the cortical deficits involved impaired dendritic arborization and spine formation. Analysis of oligodendrocytes showed that the white matter deficits involved impaired oligodendrocyte maturation and axonal myelination. These findings indicate that prolonged postnatal inflammation, without severe infection, may critically contribute to the diffuse spectrum of brain pathology and subtle long-term disability in preterm infants, with a cellular mechanism involving oligodendrocyte and neuronal dysmaturation. NODDI may be useful for clinical detection of these microstructural deficits.

Cluster Analysis of Early Postnatal Biochemical Markers May Predict Development of Retinopathy of Prematurity

Purpose

Growth factors and inflammatory and angiogenetic proteins are involved in the development of retinopathy of prematurity (ROP). However, no early biochemical markers are in clinical use to predict ROP. By performing cluster analysis of multiple biomarkers, we aimed to determine patient groups with high and low risk for developing ROP.

Methods

In total, 202 protein markers in plasma were quantified by proximity extension assay from 35 extremely preterm infants on day 2 of life. Infants were sorted in groups by automated two-dimensional hierarchical clustering of all biomarkers. ROP was classified as stages I to III with or without surgical treatment. Predictive biomarkers were evaluated by analysis of variance and detected differences by two-sided paired t-test with Bonferroni corrections for multiple comparisons.

Results

Differences in 39 biochemical markers divided infants without ROP into two control groups (control 1, n = 7; control 2, n = 5; P < 0.05). Sixty-six biochemical markers defined differences between the control groups (n = 13) and all ROP infants (n = 23; P < 0.05). PARK7, VIM, MPO, CD69, and NEMO were markedly increased in control 1 compared to all ROP infants (P < 0.001). Lower TNFRSF4 and higher HER2 and GAL appeared in infants with ROP as compared to control 1 and/or 2 (P < 0.05, respectively).

Conclusions

Our data suggest that early elevated levels of PARK7, VIM, MPO, CD69, and NEMO may be associated with lower risk of developing ROP. Lower levels of TNFRSF4 with higher levels of HER2 and GAL may predict ROP development.

Translational Relevance

Cluster analysis of early postnatal biomarkers may help to identify infants with low or high risk of developing ROP.

Hyaloid Vasculature as a Major Source of STAT3+ (Signal Transducer and Activator of Transcription 3) Myeloid Cells for Pathogenic Retinal Neovascularization in Oxygen-Induced Retinopathy

OBJECTIVE

Myeloid cells are critically involved in inflammation-induced angiogenesis, although their pathogenic role in the ischemic retina remains controversial. We hypothesize that myeloid cells contribute to pathogenic neovascularization in retinopathy of prematurity through STAT3 (signal transducer and activator of transcription 3) activation. Approach and Results: Using the mouse model of oxygen-induced retinopathy, we show that myeloid cells (CD45⁺IsolectinB4 [IB4]⁺) and particularly M2-type macrophages (CD45⁺ Arg1⁺), comprise a major source of STAT3 activation (pSTAT3) in the immature ischemic retina. Most of the pSTAT3-expressing myeloid cells concentrated at the hyaloid vasculature and their numbers were strongly correlated with the severity of pathogenic neovascular tuft formation. Pharmacological inhibition of STAT3 reduced the load of IB4⁺ cells in the hyaloid vasculature and significantly reduced the formation of pathogenic neovascular tufts during oxygen-induced retinopathy, leading to improved long-term visual outcomes (ie, increased retinal thickness and scotopic b-wave electroretinogram responses). Genetic deletion of SOCS3 (suppressor of cytokine signaling 3), an endogenous inhibitor of STAT3, in myeloid cells, enhanced pathological and physiological neovascularization in oxygen-induced retinopathy, indicating that myeloid-STAT3 signaling is crucial for retinal angiogenesis.

CONCLUSIONS

Circulating myeloid cells may migrate to the immature ischemic retina through the hyaloid vasculature and contribute to retinal neovascularization via activation of STAT3. Understanding how STAT3 modulates myeloid cells for vascular repair/pathology may provide novel therapeutic options in pathogenic angiogenesis.

Red cell distribution width and its association with retinopathy of prematurity

OBJECTIVE

The aim of this study was to evaluate whether there is a relationship between red cell distribution width (RDW) values and the development of retinopathy of prematurity (ROP) in premature infants.

METHODS

This retrospective study was conducted on a total of 159 infants with gestational age (GA) < 35 weeks including 77 infants diagnosed as ROP (patients' group) and 82 infants without ROP (control group) between September 2015 and January 2018. RDW values of the preterm infants were obtained from their medical records (routine postpartum cord blood sample and follow-up venous blood samples taken at first week, second week and first month). The possible relationship between RDW values and clinical features of ROP development was evaluated.

RESULTS

The mean GA of all infants was 29.2 ± 2.4 (24-35) weeks, and the mean birth weight was 1268 ± 419 (550-2500) g. The RDW values measured in the first and the second weeks were significantly higher in infants with ROP compared with those wihout ROP (p < .001 for both). There was no statistically significant difference between the groups in terms of cord blood and first month RDW values (p = .719, p = .108, respectively). The first and second week's RDW values of infants with ROP requiring treatment (severe ROP) were significantly higher than those of infants with ROP not requiring treatment (mild ROP) (p = .005, p = .031, respectively), but no statistically significant difference was observed between the groups in terms of cord blood and first month values (p = .114 and p = .371, respectively).

CONCLUSION

RDW is an easily accessible and inexpensive marker that may reflect the clinical risk factors for ROP. Follow-up measures of RDW have the potential to help clinicians for the prediction of ROP development in the first 2 weeks postnatally.

Effect of early prophylactic low-dose recombinant human erythropoietin on retinopathy of prematurity in very preterm infants

BACKGROUND

Very preterm infants are at risk of developing retinopathy of prematurity (ROP). Recombinant human erythropoietin (rhEPO) is routinely used to prevent anemia in preterm infants; however, the effect of rhEPO on ROP development is still controversial. The purpose of this study was to evaluate the effect of early prophylactic low-dose rhEPO administration on ROP development in very preterm infants.

METHODS

A total of 1898 preterm infants born before 32 weeks of gestation were included. Preterm infants received rhEPO (n = 950; 500 U/kg, rhEPO group) or saline (n = 948, control group) intravenously within 72 h of birth and then once every other day for 2 weeks.

RESULTS

The total incidence of ROP was not significantly different between the two groups (10.2% vs. 13.2%, p = 0.055). Further analysis showed that rhEPO group had lower rates of type 2 ROP than the control group (2.2% vs. 4.1%, RR 0.98; 95% CI 0.96-1.00; p = 0.021). Subgroup analysis found that rhEPO treatment significantly decreased the incidence of type 2 ROP in infant boys (1.8% vs. 4.3%, p = 0.021) and in those with a gestational age of 28-29^6/7 weeks (1.1% vs. 4.9%, p = 0.002) and birth weight of 1000-1499 g (1.2% vs. 4.2%, p = 0.002). There was a small increasing tendency for the incidence of ROP in infants with a gestational age of < 28 weeks after rhEPO treatment.

CONCLUSIONS

Repeated low-dose rhEPO administration has no significant influence on the development of ROP; however, it may be effective for type 2 ROP in infant boys or in infants with gestational age > 28 weeks and birth weight > 1500 g. Trial registration The data of this study were retrieved from two clinical studies registered ClinicalTrials.gov (NCT02036073) on January 14, 2014, https://clinicaltrials.gov/ct2/show/NCT02036073 ; and (NCT03919500) on April 18, 2019. https://clinicaltrials.gov/ct2/show/NCT03919500 .

Plasma metabolites in treatment-requiring retinopathy of prematurity: Potential biomarkers identified by metabolomics

Retinopathy of prematurity (ROP) is a potentially blinding condition caused by disruption of retinal vascularization and metabolism. This study aims to identify altered metabolites from plasma in patients with treatment-requiring ROP (TR-ROP) compared with controls. An untargeted metabolomics analysis was performed to reveal the metabolomic profiles of the plasma between TR-ROP patients (n = 38) and age-matched infants (n = 23). The Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted to explore the potential signaling pathways of the changed metabolites. Under positive ion mode, a total of 29 metabolites were significantly altered in plasma between TR-ROP patients and controls, and 23 altered metabolites were identified under negative ion mode. KEGG analyses indicated that "protein digestion and absorption" and "aminoacyl-tRNA biosynthesis" were the most enriched pathways of the altered metabolites. These results demonstrated that metabolomic profiles changed in plasma of TR-ROP, and the altered metabolites could be served as potential biomarkers for the diagnosis and prognosis of TR-ROP patients. Besides, the metabolomic profiles might provide clues to discover novel therapeutic strategies in ROP treatment.

Serum levels of cytokines in infants treated with conbercept for retinopathy of prematurity

Intravitreal anti-vascular endothelial growth factor (VEGF) agents have revolutionized the treatment of retinopathy of prematurity (ROP); however, there are concerns regarding the potential systemic complications caused by those treatments. This study aimed to determine the serum concentrations of cytokines in infants with ROP and to evaluate the changes in serum VEGF concentrations after intravitreal conbercept (IVC). Sixty infants with ROP treated with IVC 0.25 mg were included. Blood samples were collected before treatment as well as 1 week and 4 weeks after treatment. Serum levels of 45 types of cytokines were measured by a multiplex bead assay. We observed that IVC 0.25 mg in ROP patients suppressed the circulating levels of VEGF-A and VEGF-D as of 1 week after injection, and these growth factor levels returned to baseline at 4 weeks. No significant differences were observed in the serum levels of the other cytokines between baseline and 1 or 4 weeks after IVC.

Inflammatory and Angiogenic Mediators in Amniotic Fluid Are Associated With the Development of Retinopathy of Prematurity in Preterm Infants

Purpose

To investigate whether elevated levels of inflammatory/angiogenic and growth mediators in amniotic fluid (AF) and the presence of intra-amniotic infection are associated with the occurrence and progression of retinopathy of prematurity (ROP) in preterm infants.

Methods

This retrospective cohort study included 175 premature singleton infants who were born between 23+0 and 32+0 weeks. AF obtained via amniocentesis was cultured, and endoglin, endostatin, insulin-like growth factor-binding protein (IGFBP)-2, IGFBP-3, IGFBP-4, IL-6, IL-8, matrix metalloproteinase-8, matrix metalloproteinase-9, and vascular endothelial growth factor receptor-1 levels were assayed by ELISA. The primary outcome measures included the occurrence of any stage ROP, severe ROP (stage ≥3), and vision-threatening type 1 ROP requiring treatment.

Results

Multiple logistic regression analyses revealed that there are significant associations between elevated AF endoglin levels and ROP occurrence; between elevated AF endoglin, endostatin, and IGFBP-2 levels and severe ROP; and between high AF endoglin, IL-6, and IL-8 levels and vision-threatening ROP requiring treatment, after adjusting for potential postnatal confounders. Using stepwise regression analyses, antenatal prediction models based on these AF biomarkers and prenatal factors were developed for the ROP outcomes, which had good discriminatory power (area under the curves, 0.731-0.863). However, we found that intra-amniotic infection is not associated with ROP occurrence and progression.

Conclusions

Elevated levels of inflammatory (IL-6 and IL-8) and angiogenic (endoglin and IGFBP-2) mediators in the AF, but not the presence of intra-amniotic infection, are independently associated with the occurrence and progression of ROP in preterm infants. These findings suggest that the pathophysiologic events that predispose preterm neonates to ROP may begin before delivery.

In-line filtration in very preterm neonates: a randomized controlled trial

In-line filtration is increasingly used in critically-ill infants but its benefits, by preventing micro-particle infusion in very preterm neonates, remain to be demonstrated. We conducted a randomized controlled trial among very preterm infants allocated to receive either in-line filtration of all the intra-venous lines or standard care without filters. The primary outcome was differences greater than 20% in the median changes in pro-inflammatory cytokine serum concentrations measured at day 3 and day 8 (+/-1) using a Luminex multianalytic profiling technique. Major neonatal complications were analyzed as secondary predefined outcomes. We randomized 146 infants, assigned to filter (n = 73) or control (n = 73) group. Difference over 20% in pro-inflammatory cytokine concentration between day 3 and day 8 was not found statistically different between the two groups, both in intent-to-treat (with imputation) and per protocol (without imputation) analyses. The incidences of most of neonatal complications were found to be similar. Hence, this trial did not evidence a beneficial effect of in-line filtration in very preterm infants on the inflammatory response syndrome and neonatal morbidities. These data should be interpreted according to local standards in infusion preparation and central line management.

Current evidence and outcomes for retinopathy of prematurity prevention: insight into novel maternal and placental contributions

Retinopathy of prematurity (ROP) is a blinding morbidity of preterm infants, which represents a significant clinical problem, accounting for up to 40% of all childhood blindness. ROP displays a range of severity, though even mild disease may result in life-long visual impairment. This is complicated by the fact that our current treatments have significant ocular and potentially systemic effects. Therefore, disease prevention is desperately needed to mitigate the life-long deleterious effects of ROP for preterm infants. Although ROP demonstrates a delayed onset of retinal disease following preterm birth, representing a potential window for prevention, we have been unable to sufficiently alter the natural disease course and meaningfully prevent ROP. Prevention therapeutics requires knowledge of early ROP molecular changes and risk, occurring prior to clinical retinal disease. While we still have an incomplete understanding of these disease mechanisms, emerging data integrating contributions of maternal/placental pathobiology with ROP are poised to inform novel approaches to prevention. Herein, we review the molecular basis for current prevention strategies and the clinical outcomes of these interventions. We also discuss how insights into early ROP pathophysiology may be gained by a better understanding of maternal and placental factors playing a role in preterm birth.