Arachidonic acid and docosahexaenoic acid levels correlate with the inflammation proteome in extremely preterm infants

BACKGROUND & AIM

Clinical trials supplementing the long-chain polyunsaturated fatty acids (LCPUFAs) docosahexaenoic acid (DHA) and arachidonic acid (AA) to preterm infants have shown positive effects on inflammation-related morbidities, but the molecular mechanisms underlying these effects are not fully elucidated. This study aimed to determine associations between DHA, AA, and inflammation-related proteins during the neonatal period in extremely preterm infants.

METHODS

A retrospective exploratory study of infants (n = 183) born below 28 weeks gestation from the Mega Donna Mega trial, a randomized multicenter trial designed to study the effect of DHA and AA on retinopathy of prematurity. Serial serum samples were collected after birth until postnatal day 100 (median 7 samples per infant) and analyzed for phospholipid fatty acids and proteins using targeted proteomics covering 538 proteins. Associations over time between LCPUFAs and proteins were explored using mixed effect modeling with splines, including an interaction term for time, and adjusted for gestational age, sex, and center.

RESULTS

On postnatal day one, 55 proteins correlated with DHA levels and 10 proteins with AA levels. Five proteins were related to both fatty acids, all with a positive correlation. Over the first 100 days after birth, we identified 57 proteins to be associated with DHA and/or AA. Of these proteins, 41 (72%) related to inflammation. Thirty-eight proteins were associated with both fatty acids and the overall direction of association did not differ between DHA and AA, indicating that both LCPUFAs similarly contribute to up- and down-regulation of the preterm neonate inflammatory proteome. Primary examples of this were the inflammation-modulating cytokines IL-6 and CCL7, both being negatively related to levels of DHA and AA in the postnatal period.

CONCLUSIONS

This study supports postnatal non-antagonistic and potentially synergistic effects of DHA and AA on the inflammation proteome in preterm infants, indicating that supplementation with both fatty acids may contribute to limiting the disease burden in this vulnerable population.

CLINICAL REGISTRATION NUMBER

ClinicalTrials.gov (NCT03201588).

A versatile pumpless multi-channel fluidics system for maintenance and real-time functional assessment of tissue and cells

To address the needs of the life sciences community and the pharmaceutical industry in pre-clinical drug development to both maintain and continuously assess tissue metabolism and function with simple and rapid systems, we improved on the initial BaroFuse to develop it into a fully functional, pumpless, scalable multi-channel fluidics instrument that continuously measures changes in oxygen consumption and other endpoints in response to test compounds. We and several other laboratories assessed it with a wide range of tissue types including retina, pancreatic islets, liver, and hypothalamus with both aqueous and gaseous test compounds. The setup time was less than an hour for all collaborating groups, and there was close agreement between data obtained from the different laboratories. This easy-to-use system reliably generates real-time metabolic and functional data from tissue and cells in response to test compounds that will address a critical need in basic and applied research.

Prognostic Value of Parenteral Nutrition Duration on Risk of Retinopathy of Prematurity: Development and Validation of the Revised DIGIROP Clinical Decision Support Tool

Importance

The prognostic impact of parenteral nutrition duration (PND) on retinopathy of prematurity (ROP) is not well studied. Safe prediction models can help optimize ROP screening by effectively discriminating high-risk from low-risk infants.

Objective

To evaluate the prognostic value of PND on ROP; to update and validate the Digital ROP (DIGIROP) 2.0 birth into prescreen and screen prediction models to include all ROP-screened infants regardless of gestational age (GA) and incorporate PND; and to compare the DIGIROP model with the Weight, IGF-1, Neonatal, and ROP (WINROP) and Postnatal Growth and ROP (G-ROP) models.

Design, Setting, and Participants

This retrospective study included 11 139 prematurely born infants from 2007 to 2020 from the Swedish National Registry for ROP. Extended Poisson and logistic models were applied. Data were analyzed from August 2022 to February 2023.

Main Outcomes and Measures

Any ROP and ROP requiring treatment were studied in relation to PND. ROP treatment was the outcome in DIGIROP models. Sensitivity, specificity, area under the receiver operating characteristic curve, and adjusted OR (aOR) with 95% CI were the main measures. Internal and external validations were performed.

Results

Of 11 139 screened infants, 5071 (45.5%) were girls, and the mean (SD) gestational age was 28.5 (2.4) weeks. ROP developed in 3179 infants (29%), treatment was given in 599 (5%), 7228 (65%) had PND less than 14 days, 2308 (21%) had PND for 14 days or more, and 1603 (14%) had unknown PND. PND was significantly correlated with ROP severity (Spearman r = 0.45; P < .001). Infants with 14 days or more of PND vs less than 14 days had faster progression from any ROP to ROP treatment (adjusted mean difference, -0.9 weeks; 95% CI, -1.5 to -0.3; P = .004). Infants with PND for 14 days or more vs less than 14 days had higher odds of any ROP (aOR, 1.84; 95% CI, 1.62-2.10; P < .001) and of severe ROP requiring treatment (aOR, 2.20; 95% CI, 1.73-2.80; P < .001). Among all 11 139 infants, the DIGIROP 2.0 models had 100% sensitivity (95% CI, 99.4-100). The specificity was 46.6% (95% CI, 45.6-47.5) for the prescreen model and 76.9% (95% CI, 76.1-77.7) for the screen model. G-ROP as well as the DIGIROP 2.0 prescreen and screen models showed 100% sensitivity on a validation subset (G-ROP: sensitivity, 100%; 95% CI, 93-100; DIGIROP prescreen: sensitivity, 100%; 95% CI, 93-100; DIGIROP screen: sensitivity, 100%; 95% CI, 93-100), whereas WINROP showed 89% sensitivity (95% CI, 77-96). Specificity for each prediction model was 29% (95% CI, 22-36) for G-ROP, 38% (95% CI, 32-46) for DIGIROP prescreen, 53% (95% CI, 46-60) for DIGIROP screen at 10 weeks, and 46% (95% CI, 39-53) for WINROP.

Conclusion and Relevance

Based on more than 11 000 ROP-screened infants born in Sweden, PND of 14 days or more corresponded to a significantly higher risk of having any ROP and receiving ROP treatment. These findings provide evidence to support consideration of using the updated DIGIROP 2.0 models instead of the WINROP or G-ROP models in the management of ROP.

FGF21 via mitochondrial lipid oxidation promotes physiological vascularization in a mouse model of Phase I ROP

Hyperglycemia in early postnatal life of preterm infants with incompletely vascularized retinas is associated with increased risk of potentially blinding neovascular retinopathy of prematurity (ROP). Neovascular ROP (Phase II ROP) is a compensatory but ultimately pathological response to the suppression of physiological postnatal retinal vascular development (Phase I ROP). Hyperglycemia in neonatal mice which suppresses physiological retinal vascular growth is associated with decreased expression of systemic and retinal fibroblast growth factor 21 (FGF21). FGF21 administration promoted and FGF21 deficiency suppressed the physiological retinal vessel growth. FGF21 increased serum adiponectin (APN) levels and loss of APN abolished FGF21 promotion of physiological retinal vascular development. Blocking mitochondrial fatty acid oxidation also abolished FGF21 protection against delayed physiological retinal vessel growth. Clinically, preterm infants developing severe neovascular ROP (versus non-severe ROP) had a lower total lipid intake with more parenteral and less enteral during the first 4 weeks of life. Our data suggest that increasing FGF21 levels in the presence of adequate enteral lipids may help prevent Phase I retinopathy (and therefore prevent neovascular disease).

Validation of DIGIROP models and decision support tool for prediction of treatment for retinopathy of prematurity on a contemporary Swedish cohort

BACKGROUND/AIMS

Retinopathy of prematurity (ROP) is currently diagnosed through repeated eye examinations to find the low percentage of infants that fulfil treatment criteria to reduce vision loss. A prediction model for severe ROP requiring treatment that might sensitively and specifically identify infants that develop severe ROP, DIGIROP-Birth, was developed using birth characteristics. DIGIROP-Screen additionally incorporates first signs of ROP in different models over time. The aim was to validate DIGIROP-Birth, DIGIROP-Screen and their decision support tool on a contemporary Swedish cohort.

METHODS

Data were retrieved from the Swedish national registry for ROP (2018-2019) and two Swedish regions (2020), including 1082 infants born at gestational age (GA) 24 to <31 weeks. The predictors were GA at birth, sex, standardised birth weight and age at the first sign of ROP. The outcome was ROP treatment. Sensitivity, specificity and area under the receiver operating characteristic curve (AUC) with 95% CI were described.

RESULTS

For DIGIROP-Birth, the AUC was 0.93 (95% CI 0.90 to 0.95); for DIGIROP-Screen, it ranged between 0.93 and 0.97. The specificity was 49.9% (95% CI 46.7 to 53.0) and the sensitivity was 96.5% (95% CI 87.9 to 99.6) for the tool applied at birth. For DIGIROP-Screen, the cumulative specificity ranged between 50.0% and 78.7%. One infant with Beckwith-Wiedemann syndrome who fulfilled criteria for ROP treatment and had no missed/incomplete examinations was incorrectly flagged as not needing screening.

CONCLUSIONS

DIGIROP-Birth and DIGIROP-Screen showed high predictive ability in a contemporary Swedish cohort. At birth, 50% of the infants born at 24 to <31 weeks of gestation were predicted to have low risk of severe ROP and could potentially be released from ROP screening examinations. All routinely screened treated infants, excluding those screened for clinical indications of severe illness, were correctly flagged as needing ROP screening.

Modification of serum fatty acids in preterm infants by parenteral lipids and enteral docosahexaenoic acid/arachidonic acid: A secondary analysis of the Mega Donna Mega trial

BACKGROUND & AIM

Preterm infants risk deficits of long-chain polyunsaturated fatty acids (LCPUFAs) that may contribute to morbidities and hamper neurodevelopment. We aimed to determine longitudinal serum fatty acid profiles in preterm infants and how the profiles are affected by enteral and parenteral lipid sources.

METHODS

Cohort study analyzing fatty acid data from the Mega Donna Mega study, a randomized control trial with infants born <28 weeks of gestation (n = 204) receiving standard nutrition or daily enteral lipid supplementation with arachidonic acid (AA):docosahexaenoic acid (DHA) (100:50 mg/kg/day). Infants received an intravenous lipid emulsion containing olive oil:soybean oil (4:1). Infants were followed from birth to postmenstrual age 40 weeks. Levels of 31 different fatty acids from serum phospholipids were determined by GC-MS and reported in relative (mol%) and absolute concentration (μmol l-1) units.

RESULTS

Higher parenteral lipid administration resulted in lower serum proportion of AA and DHA relative to other fatty acids during the first 13 weeks of life (p < 0.001 for the 25th vs the 75th percentile). The enteral AA:DHA supplement increased the target fatty acids with little impact on other fatty acids. The absolute concentration of total phospholipid fatty acids changed rapidly in the first weeks of life, peaking at day 3, median (Q1-Q3) 4452 (3645-5466) μmol l-1, and was positively correlated to the intake of parenteral lipids. Overall, infants displayed common fatty acid trajectories over the study period. However, remarkable differences in fatty acid patterns were observed depending on whether levels were expressed in relative or absolute units. For example, the relative levels of many LCPUFAs, including DHA and AA, declined rapidly after birth while their absolute concentrations increased in the first week of life. For DHA, absolute levels were significantly higher compared to cord blood from day 1 until postnatal week 16 (p < 0.001). For AA, absolute postnatal levels were lower compared to cord blood from week 4 throughout the study period (p < 0.05).

CONCLUSIONS

Our data show that parenteral lipids aggravate the postnatal loss of LCPUFAs seen in preterm infants and that serum AA available for accretion is below that in utero. Further research is needed to establish optimal postnatal fatty acid supplementation and profiles in extremely preterm infants to promote development and long-term health.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov, identifier: NCT03201588.

Therapeutic activation of endothelial sphingosine-1-phosphate receptor 1 by chaperone-bound S1P suppresses proliferative retinal neovascularization

Sphingosine-1-phosphate (S1P), the circulating HDL-bound lipid mediator that acts via S1P receptors (S1PR), is required for normal vascular development. The role of this signaling axis in vascular retinopathies is unclear. Here, we show in a mouse model of oxygen-induced retinopathy (OIR) that endothelial overexpression of S1pr1 suppresses while endothelial knockout of S1pr1 worsens neovascular tuft formation. Furthermore, neovascular tufts are increased in Apom-/- mice which lack HDL-bound S1P while they are suppressed in ApomTG mice which have more circulating HDL-S1P. These results suggest that circulating HDL-S1P activation of endothelial S1PR1 suppresses neovascular pathology in OIR. Additionally, systemic administration of ApoM-Fc-bound S1P or a small-molecule Gi-biased S1PR1 agonist suppressed neovascular tuft formation. Circulating HDL-S1P activation of endothelial S1PR1 may be a key protective mechanism to guard against neovascular retinopathies that occur not only in premature infants but also in diabetic patients and aging people.

In vivo noninvasive mitochondrial redox assessment of the optic nerve head to predict disease

Eye diseases are diagnosed by visualizing often irreversible structural changes occurring late in disease progression, such as retinal ganglion cell loss in glaucoma. The retina and optic nerve head have high mitochondrial energy need. Early mitochondrial/energetics dysfunction may predict vulnerability to permanent structural changes. In the in vivo murine eye, we used light-based resonance Raman spectroscopy (RRS) to assess noninvasively the redox states of mitochondria and hemoglobin which reflect availability of electron donors (fuel) and acceptors (oxygen). As proof of principle, we demonstrated that the mitochondrial redox state at the optic nerve head correlates with later retinal ganglion loss after acute intraocular pressure (IOP) elevation. This technology can potentially map the metabolic health of eye tissue in vivo complementary to optical coherence tomography, defining structural changes. Early detection (and normalization) of mitochondrial dysfunction before irreversible damage could lead to prevention of permanent neural loss.

Cytochrome P450 oxidase 2J inhibition suppresses choroidal neovascularization in mice

INTRODUCTION

Choroidal neovascularization (CNV) in age-related macular degeneration (AMD) leads to blindness. It has been widely reported that increased intake of ω-3 long-chain polyunsaturated fatty acids (LCPUFA) diets reduce CNV. Of the three major pathways metabolizing ω-3 (and ω-6 LCPUFA), the cyclooxygenase and lipoxygenase pathways generally produce pro-angiogenic metabolites from ω-6 LCPUFA and anti-angiogenic ones from ω-3 LCPUFA. Howevehr, cytochrome P450 oxidase (CPY) 2C produces pro-angiogenic metabolites from both ω-6 and ω-3 LCPUFA. The effects of CYP2J2 products on ocular neovascularization are still unknown. Understanding how each metabolic pathway affects the protective effect of ω-3 LCPUFA on retinal neovascularization may lead to therapeutic interventions.

OBJECTIVES

To investigate the effects of LCPUFA metabolites through CYP2J2 pathway and CYP2J2 regulation on CNV both in vivo and ex vivo.

METHODS

The impact of CYP2J2 overexpression and inhibition on neovascularization in the laser-induced CNV mouse model was assessed. The plasma levels of CYP2J2 metabolites were measured by liquid chromatography and tandem mass spectroscopy. The choroidal explant sprouting assay was used to investigate the effects of CYP2J2 inhibition and specific LCPUFA CYP2J2 metabolites on angiogenesis ex vivo.

RESULTS

CNV was exacerbated in Tie2-Cre CYP2J2-overexpressing mice and was associated with increased levels of plasma docosahexaenoic acids. Inhibiting CYP2J2 activity with flunarizine decreased CNV in both ω-6 and ω-3 LCPUFA-fed wild-type mice. In Tie2-Cre CYP2J2-overexpressing mice, flunarizine suppressed CNV by 33 % and 36 % in ω-6, ω-3 LCPUFA diets, respectively, and reduced plasma levels of CYP2J2 metabolites. The pro-angiogenic role of CYP2J2 was corroborated in the choroidal explant sprouting assay. Flunarizine attenuated ex vivo choroidal sprouting, and 19,20-EDP, a ω-3 LCPUFA CYP2J2 metabolite, increased sprouting. The combined inhibition of CYP2J2 with flunarizine and CYP2C8 with montelukast further enhanced CNV suppression via tumor necrosis factor-α suppression.

CONCLUSIONS

CYP2J2 inhibition augmented the inhibitory effect of ω-3 LCPUFA on CNV. Flunarizine suppressed pathological choroidal angiogenesis, and co-treatment with montelukast inhibiting CYP2C8 further enhanced the effect. CYP2 inhibition might be a viable approach to suppress CNV in AMD.

Neurodevelopmental disorders and somatic diagnoses in a national cohort of children born before 24 weeks of gestation

AIM

This study investigated childhood diagnoses in children born extremely preterm before 24 weeks of gestation.

METHODS

Diagnoses of neurodevelopmental disorders and selected somatic diagnoses were retrospectively retrieved from national Swedish registries for children born before 24 weeks from 2007 to 2018. Their individual medical files were also examined.

RESULTS

We studied 383 children born at a median of 23.3 (range 21.9-23.9) weeks, with a median birthweight of 565 (range 340-874) grams. Three-quarters (75%) had neurodevelopmental disorders, including speech disorders (52%), intellectual disabilities (40%), attention deficit hyperactivity disorder (30%), autism spectrum disorders (24%), visual impairment (22%), cerebral palsy (17%), epilepsy (10%) and hearing impairment (5%). More boys than girls born at 23 weeks had intellectual disabilities (45% vs. 27%, p < 0.01) and visual impairment (25% vs. 14%, p < 0.01). Just over half of the cohort (55%) received habilitation care. The majority (88%) had somatic diagnoses, including asthma (63%) and failure to thrive/short stature (39%).

CONCLUSION

Most children born before 24 weeks had neurodevelopmental disorders and/or additional somatic diagnoses in childhood and were referred to habilitation services. Clinicians should be aware of the multiple health and developmental problems affecting these children. Resources are needed to identify their long-term support needs at an early stage.

Association of Docosahexaenoic Acid and Arachidonic Acid Serum Levels With Retinopathy of Prematurity in Preterm Infants

IMPORTANCE

Supplementing preterm infants with long-chain polyunsaturated fatty acids (LC-PUFA) has been inconsistent in reducing the severity and incidence of retinopathy of prematurity (ROP). Furthermore, few studies have measured the long-term serum lipid levels after supplementation.

OBJECTIVE

To assess whether ROP severity is associated with serum levels of LC-PUFA, especially docosahexaenoic acid (DHA) and arachidonic acid (AA), during the first 28 postnatal days.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed the Mega Donna Mega study, a randomized clinical trial that provided enteral fatty acid supplementation at 3 neonatal intensive care units in Sweden. Infants included in this cohort study were born at a gestational age of less than 28 weeks between December 20, 2016, and August 6, 2019.

MAIN OUTCOMES AND MEASURES

Severity of ROP was classified as no ROP, mild or moderate ROP (stage 1-2), or severe ROP (stage 3 and type 1). Serum phospholipid fatty acids were measured through gas chromatography-mass spectrometry. Ordinal logistic regression, with a description of unadjusted odds ratio (OR) as well as gestational age- and birth weight-adjusted ORs and 95% CIs, was used. Areas under the curve were used to calculate mean daily levels of fatty acids during postnatal days 1 to 28. Blood samples were obtained at the postnatal ages of 1, 3, 7, 14, and 28 days.

RESULTS

A total of 175 infants were included in analysis. Of these infants, 99 were boys (56.6%); the median (IQR) gestational age was 25 weeks 5 days (24 weeks 3 days to 26 weeks 6 days), and the median (IQR) birth weight was 785 (650-945) grams. A higher DHA proportion was seen in infants with no ROP compared with those with mild or moderate ROP or severe ROP (OR per 0.5-molar percentage increase, 0.49 [95% CI, 0.36-0.68]; gestational age- and birth weight-adjusted OR, 0.66 [95% CI, 0.46-0.93]). The corresponding adjusted OR for AA levels per 1-molar percentage increase was 0.83 (95% CI, 0.66-1.05). The association between DHA levels and ROP severity appeared only in infants with sufficient AA levels, suggesting that a mean daily minimum level of 7.8 to 8.3 molar percentage of AA was necessary for a detectable association between DHA level and less severe ROP.

CONCLUSIONS AND RELEVANCE

This cohort study found that higher mean daily serum levels of DHA during the first 28 postnatal days were associated with less severe ROP even after adjustment for known risk factors, but only in infants with sufficiently high AA levels. Further studies are needed to identify LC-PUFA supplementation strategies that may prevent ROP and other morbidities.

Insulin-Like Growth Factor 1 in the Preterm Rabbit Pup: Characterization of Cerebrovascular Maturation following Administration of Recombinant Human Insulin-Like Growth Factor 1/Insulin-Like Growth Factor 1-Binding Protein 3

Following preterm birth, serum levels of insulin-like growth factor 1 (IGF-1) decrease compared to corresponding in utero levels. A recent clinical trial indicated that supplementation with recombinant human (rh) IGF-1/rhIGF-binding protein 3 (rhIGF-1/rhIGFBP-3) prevents severe intraventricular hemorrhage (IVH) in extremely preterm infants. In a preterm rabbit pup model, we characterized endogenous serum and hepatic IGF-1, along with brain distribution of IGF-1 and IGF-1 receptor (IGF1R). We then evaluated the effects of rhIGF-1/rhIGFBP-3 on gene expression of regulators of cerebrovascular maturation and structure. Similar to preterm infants, serum IGF-1 concentrations decreased rapidly after preterm birth in the rabbit pup. Administration of rhIGF-1/rhIGFBP-3 restored in utero serum levels but was rapidly eliminated. Immunolabeled IGF1R was widely distributed in multiple brain regions, displaying an abundant density in the choroid plexus and sub-ependymal germinal zones. Increased IGF-1 immunoreactivity, distributed as IGF1R, was detected 4 h after rhIGF-1/rhIGFBP-3 administration. The rhIGF-1/rhIGFBP-3 treatment led to upregulation of choroid plexus genes involved in vascular maturation and structure, with corresponding protein translation for most of these genes. The preterm rabbit pup model is well suited for evaluation of IGF-1-based prevention of IVH. Administration of rhIGF-1/rhIGFBP-3 affects cerebrovascular maturation, suggesting a role for it in preventing preterm IVH.

Cellular senescence in pathologic retinal angiogenesis

Pathologic angiogenesis causes blindness in many eye diseases. Crespo-Garcia, Tsuruda, and Dejda et al. employed bioinformatics to characterize cell senescence as a primary factor in the common pathogenesis of retinopathies. They validated their findings using human and mouse retina with proliferative retinopathy. Clearance of senescent cells suppressed neovessel growth.

Sphingolipidomics of serum in extremely preterm infants: Association between low sphingosine-1-phosphate levels and severe retinopathy of prematurity

BACKGROUND

Extremely preterm infants are at risk of developing retinopathy of prematurity (ROP) that can cause impaired vision or blindness. Changes in blood lipids have been associated with ROP. This study aimed to monitor longitudinal changes in the serum sphingolipidome of extremely preterm infants and investigate the relationship to development of severe ROP.

METHODS

This is a prospective study that included 47 infants born <28 gestational weeks. Serum samples were collected from cord blood and at postnatal days 1, 7, 14, and 28, and at postmenstrual weeks (PMW) 32, 36, and 40. Serum sphingolipids and phosphatidylcholines were extracted and analyzed by LC-MS/MS. Associations between sphingolipid species and ROP were assessed using mixed models for repeated measures.

RESULTS

The serum concentration of all investigated lipid classes, including ceramide, mono- di- and trihexosylceramide, sphingomyelin, and phosphatidylcholine displayed distinct temporal patterns between birth and PMW40. There were also substantial changes in the lipid species composition within each class. Among the analyzed sphingolipid species, sphingosine-1-phosphate showed the strongest association with severe ROP, and this association was independent of gestational age at birth and weight standard deviation score change.

CONCLUSIONS

The serum phospho- and sphingolipidome undergoes significant remodeling during the first weeks of the preterm infant's life. Low postnatal levels of the signaling lipid sphingosine-1-phosphate are associated with the development of severe ROP.

Individual Risk Prediction for Sight-Threatening Retinopathy of Prematurity Using Birth Characteristics

Question

Can a prediction model be constructed for retinopathy of prematurity needing treatment by using only birth characteristics data and applying advanced statistical methods?

Findings

In this cohort study of 6947 infants born at gestational age 24 to 30 weeks, the prediction model incorporating only postnatal age, gestational age, sex, and birth weight provided a predictive ability for retinopathy of prematurity needing treatment that was comparable to current models requiring postnatal data (not always available). The risk for retinopathy of prematurity needing treatment increased up to 12 weeks’ postnatal age irrespective of the infants’ gestational age.

Meaning

This prediction model identifying infants with a high risk for developing sight-threatening disease at an early time may improve the conditions for optimal screening.

Importance

To prevent blindness, repeated infant eye examinations are performed to detect severe retinopathy of prematurity (ROP), yet only a small fraction of those screened need treatment. Early individual risk stratification would improve screening timing and efficiency and potentially reduce the risk of blindness.

Objectives

To create and validate an easy-to-use prediction model using only birth characteristics and to describe a continuous hazard function for ROP treatment.

Design, Setting, and Participants

In this retrospective cohort study, Swedish National Patient Registry data from infants screened for ROP (born between January 1, 2007, and August 7, 2018) were analyzed with Poisson regression for time-varying data (postnatal age, gestational age [GA], sex, birth weight, and important interactions) to develop an individualized predictive model for ROP treatment (called DIGIROP-Birth [Digital ROP]). The model was validated internally and externally (in US and European cohorts) and compared with 4 published prediction models.

Main Outcomes and Measures

The study outcome was ROP treatment. The measures were estimated momentary and cumulative risks, hazard ratios with 95% CIs, area under the receiver operating characteristic curve (hereinafter referred to as AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

Results

Among 7609 infants (54.6% boys; mean [SD] GA, 28.1 [2.1] weeks; mean [SD] birth weight, 1119 [353] g), 442 (5.8%) were treated for ROP, including 142 (40.1%) treated of 354 born at less than 24 gestational weeks. Irrespective of GA, the risk for receiving ROP treatment increased during postnatal weeks 8 through 12 and decreased thereafter. Validations of DIGIROP-Birth for 24 to 30 weeks’ GA showed high predictive ability for the model overall (AUC, 0.90 [95% CI, 0.89-0.92] for internal validation, 0.94 [95% CI, 0.90-0.98] for temporal validation, 0.87 [95% CI, 0.84-0.89] for US external validation, and 0.90 [95% CI, 0.85-0.95] for European external validation) by calendar periods and by race/ethnicity. The sensitivity, specificity, PPV, and NPV were numerically at least as high as those obtained from CHOP-ROP (Children’s Hospital of Philadelphia–ROP), OMA-ROP (Omaha-ROP), WINROP (weight, insulinlike growth factor 1, neonatal, ROP), and CO-ROP (Colorado-ROP), models requiring more complex postnatal data.

Conclusions and Relevance

This study validated an individualized prediction model for infants born at 24 to 30 weeks’ GA, enabling early risk prediction of ROP treatment based on birth characteristics data. Postnatal age rather than postmenstrual age was a better predictive variable for the temporal risk of ROP treatment. The model is an accessible online application that appears to be generalizable and to have at least as good test statistics as other models requiring longitudinal neonatal data not always readily available to ophthalmologists.

Glycolysis links reciprocal activation of myeloid cells and endothelial cells in the retinal angiogenic niche

The coordination of metabolic signals among different cellular components in pathological retinal angiogenesis is poorly understood. Here, we showed that in the pathological angiogenic vascular niche, retinal myeloid cells, particularly macrophages/microglia that are spatially adjacent to endothelial cells (ECs), are highly glycolytic. We refer to these macrophages/microglia that exhibit a unique angiogenic phenotype with increased expression of both M1 and M2 markers and enhanced production of both proinflammatory and proangiogenic cytokines as pathological retinal angiogenesis-associated glycolytic macrophages/microglia (PRAGMs). The phenotype of PRAGMs was recapitulated in bone marrow-derived macrophages or retinal microglia stimulated by lactate that was produced by hypoxic retinal ECs. Knockout of 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase (PFKFB3; Pfkfb3 for rodents), a glycolytic activator in myeloid cells, impaired the ability of macrophages/microglia to acquire an angiogenic phenotype, rendering them unable to promote EC proliferation and sprouting and pathological neovascularization in a mouse model of oxygen-induced proliferative retinopathy. Mechanistically, hyperglycolytic macrophages/microglia produced large amount of acetyl-coenzyme A, leading to histone acetylation and PRAGM-related gene induction, thus reprogramming macrophages/microglia into an angiogenic phenotype. These findings reveal a critical role of glycolytic metabolites as initiators of reciprocal activation of macrophages/microglia and ECs in the retinal angiogenic niche and suggest that strategies targeting the metabolic communication between these cell types may be efficacious in the treatment of pathological retinal angiogenesis.

Development and validation of a new clinical decision support tool to optimize screening for retinopathy of prematurity

BACKGROUND/AIMS

Prematurely born infants undergo costly, stressful eye examinations to uncover the small fraction with retinopathy of prematurity (ROP) that needs treatment to prevent blindness. The aim was to develop a prediction tool (DIGIROP-Screen) with 100% sensitivity and high specificity to safely reduce screening of those infants not needing treatment. DIGIROP-Screen was compared with four other ROP models based on longitudinal weights.

METHODS

Data, including infants born at 24-30 weeks of gestational age (GA), for DIGIROP-Screen development (DevGroup, N=6991) originate from the Swedish National Registry for ROP. Three international cohorts comprised the external validation groups (ValGroups, N=1241). Multivariable logistic regressions, over postnatal ages (PNAs) 6-14 weeks, were validated. Predictors were birth characteristics, status and age at first diagnosed ROP and essential interactions.

RESULTS

ROP treatment was required in 287 (4.1%)/6991 infants in DevGroup and 49 (3.9%)/1241 in ValGroups. To allow 100% sensitivity in DevGroup, specificity at birth was 53.1% and cumulatively 60.5% at PNA 8 weeks. Applying the same cut-offs in ValGroups, specificities were similar (46.3% and 53.5%). One infant with severe malformations in ValGroups was incorrectly classified as not needing screening. For all other infants, at PNA 6-14 weeks, sensitivity was 100%. In other published models, sensitivity ranged from 88.5% to 100% and specificity ranged from 9.6% to 45.2%.

CONCLUSIONS

DIGIROP-Screen, a clinical decision support tool using readily available birth and ROP screening data for infants born GA 24-30 weeks, in the European and North American populations tested can safely identify infants not needing ROP screening. DIGIROP-Screen had equal or higher sensitivity and specificity compared with other models. DIGIROP-Screen should be tested in any new cohort for validation and if not validated it can be modified using the same statistical approaches applied to a specific clinical setting.

Effect of Enteral Lipid Supplement on Severe Retinopathy of Prematurity: A Randomized Clinical Trial

IMPORTANCE

Lack of arachidonic acid (AA) and docosahexaenoic acid (DHA) after extremely preterm birth may contribute to preterm morbidity, including retinopathy of prematurity (ROP).

OBJECTIVE

To determine whether enteral supplementation with fatty acids from birth to 40 weeks' postmenstrual age reduces ROP in extremely preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

The Mega Donna Mega trial, a randomized clinical trial, was a multicenter study performed at 3 university hospitals in Sweden from December 15, 2016, to December 15, 2019. The screening pediatric ophthalmologists were masked to patient groupings. A total of 209 infants born at less than 28 weeks' gestation were tested for eligibility, and 206 infants were included. Efficacy analyses were performed on as-randomized groups on the intention-to-treat population and on the per-protocol population using as-treated groups. Statistical analyses were performed from February to April 2020.

INTERVENTIONS

Infants received either supplementation with an enteral oil providing AA (100 mg/kg/d) and DHA (50 mg/kg/d) (AA:DHA group) or no supplementation within 3 days after birth until 40 weeks' postmenstrual age.

MAIN OUTCOMES AND MEASURES

The primary outcome was severe ROP (stage 3 and/or type 1). The secondary outcomes were AA and DHA serum levels and rates of other complications of preterm birth.

RESULTS

A total of 101 infants (58 boys [57.4%]; mean [SD] gestational age, 25.5 [1.5] weeks) were included in the AA:DHA group, and 105 infants (59 boys [56.2%]; mean [SD] gestational age, 25.5 [1.4] weeks) were included in the control group. Treatment with AA and DHA reduced severe ROP compared with the standard of care (16 of 101 [15.8%] in the AA:DHA group vs 35 of 105 [33.3%] in the control group; adjusted relative risk, 0.50 [95% CI, 0.28-0.91]; P = .02). The AA:DHA group had significantly higher fractions of AA and DHA in serum phospholipids compared with controls (overall mean difference in AA:DHA group, 0.82 mol% [95% CI, 0.46-1.18 mol%]; P < .001; overall mean difference in control group, 0.13 mol% [95% CI, 0.01-0.24 mol%]; P = .03). There were no significant differences between the AA:DHA group and the control group in the rates of bronchopulmonary dysplasia (48 of 101 [47.5%] vs 48 of 105 [45.7%]) and of any grade of intraventricular hemorrhage (43 of 101 [42.6%] vs 42 of 105 [40.0%]). In the AA:DHA group and control group, respectively, sepsis occurred in 42 of 101 infants (41.6%) and 53 of 105 infants (50.5%), serious adverse events occurred in 26 of 101 infants (25.7%) and 26 of 105 infants (24.8%), and 16 of 101 infants (15.8%) and 13 of 106 infants (12.3%) died.

CONCLUSIONS AND RELEVANCE

This study found that, compared with standard of care, enteral AA:DHA supplementation lowered the risk of severe ROP by 50% and showed overall higher serum levels of both AA and DHA. Enteral lipid supplementation with AA:DHA is a novel preventive strategy to decrease severe ROP in extremely preterm infants.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03201588.

Retinal glial remodeling by FGF21 preserves retinal function during photoreceptor degeneration

The group of retinal degenerations, retinitis pigmentosa (RP), comprises more than 150 genetic abnormalities affecting photoreceptors. Finding degenerative pathways common to all genetic abnormalities may allow general treatment such as neuroprotection. Neuroprotection may include enhancing the function of cells that directly support photoreceptors, retinal pigment epithelial cells, and Müller glia. Treatment with fibroblast growth factor 21 (FGF21), a neuroprotectant, from postnatal week 4-10, during rod and cone loss in P23H mice (an RP model) with retinal degeneration, preserved photoreceptor function and normalized Müller glial cell morphology. Single-cell transcriptomics of retinal cells showed that FGF21 receptor Fgfr1 was specifically expressed in Müller glia/astrocytes. Of all retinal cells, FGF21 predominantly affected genes in Müller glia/astrocytes with increased expression of axon development and synapse formation pathway genes. Therefore, enhancing retinal glial axon and synapse formation with neurons may preserve retinal function in RP and may suggest a general therapeutic approach for retinal degenerative diseases.

Validation of the Retinopathy of Prematurity Activity Scale (ROP-ActS) using retrospective clinical data

PURPOSE

The International Neonatal Consortium recently published a proposed retinopathy of prematurity (ROP) activity scale intended for use in clinical trials after validation. The aim of this study was to validate the ROP activity scale (ROP-ActS) in a ROP screened cohort with protocol based collected data by evaluating the ability of the ROP-Act scores to predict ROP treatment. In addition, we aimed to evaluate the scale's sensitivity characteristic of disease severity by studying association with gestational age (GA) in comparison with conventionally used ROP stage and zone.

METHODS

A cohort of 535 preterm infants with 3324 ROP examinations with an end-point of ROP treatment or end of screening in Gothenburg, Sweden, was included. Median GA was 28.1 weeks, 47.5% were girls, and 74 (13.8%) infants were treated for ROP. The validation was performed by estimating probabilities for ROP treatment, and by applying logistic and linear regression.

RESULTS

The original ROP-ActS was overall well-ordered with respect to ability to predict ROP treatment but could be improved by re-ordering score 3 (zone II stage 1) and 5 (zone III stage 3) based on our clinical cohort data. The modified ROP-ActS was superior to ROP stage and zone in the prediction analysis of ROP treatment. Modified ROP-ActS was more strongly related to GA than currently used ROP stage, but not zone.

CONCLUSION

In the studied cohort, the modified ROP-ActS could better predict ROP treatment compared to ROP stage and zone. Retinopathy of Prematurity Activity Scale (ROP-ActS) had a superior sensitivity characteristic studied through association to GA than conventionally used ROP stage.

Fatty acid oxidation and photoreceptor metabolic needs

Photoreceptors have high energy demands and a high density of mitochondria that produce ATP through oxidative phosphorylation (OXPHOS) of fuel substrates. Although glucose is the major fuel for CNS brain neurons, in photoreceptors (also CNS), most glucose is not metabolized through OXPHOS but is instead metabolized into lactate by aerobic glycolysis. The major fuel sources for photoreceptor mitochondria remained unclear for almost six decades. Similar to other tissues (like heart and skeletal muscle) with high metabolic rates, photoreceptors were recently found to metabolize fatty acids (palmitate) through OXPHOS. Disruption of lipid entry into photoreceptors leads to extracellular lipid accumulation, suppressed glucose transporter expression, and a duel lipid/glucose fuel shortage. Modulation of lipid metabolism helps restore photoreceptor function. However, further elucidation of the types of lipids used as retinal energy sources, the metabolic interaction with other fuel pathways, as well as the cross-talk among retinal cells to provide energy to photoreceptors is not fully understood. In this review, we will focus on the current understanding of photoreceptor energy demand and sources, and potential future investigations of photoreceptor metabolism.

Vitreous metabolomics profiling of proliferative diabetic retinopathy

AIMS/HYPOTHESIS

Proliferative diabetic retinopathy (PDR) with retinal neovascularisation (NV) is a leading cause of vision loss. This study identified a set of metabolites that were altered in the vitreous humour of PDR patients compared with non-diabetic control participants. We corroborated changes in vitreous metabolites identified in prior studies and identified novel dysregulated metabolites that may lead to treatment strategies for PDR.

METHODS

We analysed metabolites in vitreous samples from 43 PDR patients and 21 non-diabetic epiretinal membrane control patients from Japan (age 27-80 years) via ultra-high-performance liquid chromatography-mass spectrometry. We then investigated the association of a novel metabolite (creatine) with retinal NV in mouse oxygen-induced retinopathy (OIR). Creatine or vehicle was administered from postnatal day (P)12 to P16 (during induced NV) via oral gavage. P17 retinas were quantified for NV and vaso-obliteration.

RESULTS

We identified 158 metabolites in vitreous samples that were altered in PDR patients vs control participants. We corroborated increases in pyruvate, lactate, proline and allantoin in PDR, which were identified in prior studies. We also found changes in metabolites not previously identified, including creatine. In human vitreous humour, creatine levels were decreased in PDR patients compared with epiretinal membrane control participants (false-discovery rate <0.001). We validated that lower creatine levels were associated with vascular proliferation in mouse retina in the OIR model (p = 0.027) using retinal metabolomics. Oral creatine supplementation reduced NV compared with vehicle (P12 to P16) in OIR (p = 0.0024).

CONCLUSIONS/INTERPRETATION

These results suggest that metabolites from vitreous humour may reflect changes in metabolism that can be used to find pathways influencing retinopathy. Creatine supplementation could be useful to suppress NV in PDR. Graphical abstract.

Notice of Withdrawal: Retinal Vasculature in Development and Diseases

This article was withdrawn on October 15, 2020, at the request of the journal editors, with agreement from the authors, owing to a substantial amount of unattributed or improperly cited text overlap with other sources. In accordance with Annual Reviews' commitment to transparency, the original PDF of the article remains available for download at https://www.annualreviews.org/doi/pdf/10.1146/annurev-vision-091517-034018.

An Ex Vivo Choroid Sprouting Assay of Ocular Microvascular Angiogenesis

Pathological choroidal angiogenesis, a salient feature of age-related macular degeneration, leads to vision impairment and blindness. Endothelial cell (EC) proliferation assays using human retinal microvascular endothelial cells (HRMECs) or isolated primary retinal ECs are widely used in vitro models to study retinal angiogenesis. However, isolating pure murine retinal endothelial cells is technically challenging and retinal ECs may have different proliferation responses than choroidal endothelial cells and different cell/cell interactions. A highly reproducible ex vivo choroidal sprouting assay as a model of choroidal microvascular proliferation was developed. This model includes the interaction between choroid vasculature (EC, macrophages, pericytes) and retinal pigment epithelium (RPE). Mouse RPE/choroid/scleral explants are isolated and incubated in growth-factor-reduced basal membrane extract (BME) (day 0). Medium is changed every other day and choroid sprouting is quantified at day 6. The images of individual choroid explant are taken with an inverted phase microscope and the sprouting area is quantified using a semi-automated macro plug-in to the ImageJ software developed in this lab. This reproducible ex vivo choroidal sprouting assay can be used to assess compounds for potential treatment and for microvascular disease research to assess pathways involved in choroidal micro vessel proliferation using wild type and genetically modified mouse tissue.

Docosahexaenoic Acid and Arachidonic Acid Levels Are Associated with Early Systemic Inflammation in Extremely Preterm Infants

Fetal and early postnatal inflammation have been associated with increased morbidity in extremely preterm infants. This study aimed to demonstrate if postpartum levels of docosahexaenoic acid (DHA) and arachidonic acid (AA) were associated with early inflammation. In a cohort of 90 extremely preterm infants, DHA and AA in cord blood, on the first postnatal day and on postnatal day 7 were examined in relation to early systemic inflammation, defined as elevated C-reactive protein (CRP) and/or interleukin-6 (IL-6) within 72 h from birth, with or without positive blood culture. Median serum level of DHA was 0.5 mol% (95% CI (confidence interval) 0.2–0.9, P = 0.006) lower than the first postnatal day in infants with early systemic inflammation, compared to infants without signs of inflammation, whereas levels of AA were not statistically different between infants with and without signs of inflammation. In cord blood, lower serum levels of both DHA (correlation coefficient −0.40; P = 0.010) and AA (correlation coefficient −0.54; p < 0.001) correlated with higher levels of IL-6. Levels of DHA or AA did not differ between infants with and without histological signs of chorioamnionitis or fetal inflammation. In conclusion, serum levels of DHA at birth were associated with the inflammatory response during the early postnatal period in extremely preterm infants.

Free fatty acid receptor 4 activation protects against choroidal neovascularization in mice

To examine whether free fatty acid receptor 4 (FFAR4) activation can protect against choroidal neovascularization (CNV), which is a common cause of blindness, and to elucidate the mechanism underlying the inhibition, we used the mouse model of laser-induced CNV to mimic angiogenic aspects of age-related macular degeneration (AMD). Laser-induced CNV was compared between groups treated with an FFAR4 agonist or vehicle, and between FFAR4 wild-type (Ffar4^+/+) and knock out (Ffar4^-/-) mice on a C57BL/6J/6N background. The ex vivo choroid-sprouting assay, including primary retinal pigment epithelium (RPE) and choroid, without retina was used to investigate whether FFAR4 affects choroidal angiogenesis. Western blotting for pNF-ĸB/NF-ĸB and qRT-PCR for Il-6, Il-1β, Tnf-α, Vegf, and Nf-ĸb were used to examine the influence of FFAR4 on inflammation, known to influence CNV. RPE isolated from Ffar4^+/+ and Ffar4^-/- mice were used to assess RPE contribution to inflammation. The FFAR4 agonist suppressed laser-induced CNV in C57BL/6J mice, and CNV increased in Ffar4^-/- compared to Ffar4^+/+ mice. We showed that the FFAR4 agonist acted through the FFAR4 receptor. The FFAR4 agonist suppressed mRNA expression of inflammation markers (Il-6, Il-1β) via the NF-ĸB pathway in the retina, choroid, RPE complex. The FFAR4 agonist suppressed neovascularization in the choroid-sprouting ex vivo assay and FFAR4 deficiency exacerbated sprouting. Inflammation markers were increased in primary RPE cells of Ffar4^-/- mice compared with Ffar4^+/+ RPE. In this mouse model, the FFAR4 agonist suppressed CNV, suggesting FFAR4 to be a new molecular target to reduce pathological angiogenesis in CNV.

Sphingosine 1-Phosphate Receptor Signaling Establishes AP-1 Gradients to Allow for Retinal Endothelial Cell Specialization

Transcriptional mechanisms that drive angiogenesis and organotypic vascular endothelial cell specialization are poorly understood. Here, we show that retinal endothelial sphingosine 1-phosphate receptors (S1PRs), which restrain vascular endothelial growth factor (VEGF)-induced angiogenesis, spatially restrict expression of JunB, a member of the activator protein 1 (AP-1) family of transcription factors (TFs). Mechanistically, VEGF induces JunB expression at the sprouting vascular front while S1PR-dependent vascular endothelial (VE)-cadherin assembly suppresses JunB expression in the nascent vascular network, thus creating a gradient of this TF. Endothelial-specific JunB knockout mice showed diminished expression of neurovascular guidance genes and attenuated retinal vascular network progression. In addition, endothelial S1PR signaling is required for normal expression of β-catenin-dependent genes such as TCF/LEF1 and ZIC3 TFs, transporters, and junctional proteins. These results show that S1PR signaling restricts JunB function to the expanding vascular front, thus creating an AP-1 gradient and enabling organotypic endothelial cell specialization of the vascular network.

Randomized Control Trial of Postnatal rhIGF-1/rhIGFBP-3 Replacement in Preterm Infants: Post-hoc Analysis of Its Effect on Brain Injury

Background: Postnatal insulin-like growth factor-1 (IGF-1) replacement with recombinant human (rh)IGF-1 and IGF binding protein-3 (rhIGF-1/rhIGFBP-3) is being studied as a potential treatment to reduce comorbidities of prematurity. We have recently reported on a phase II, multicenter, randomized, controlled trial comparing postnatal rhIGF-1/rhIGFBP-3 replacement with standard of care (SOC) in extremely preterm infants (NCT01096784). Maximum severity of retinopathy of prematurity was the primary endpoint of the trial and presence of GMH-IVH/PHI one of the pre-specified secondary endpoints. Infants therefore received serial cranial ultrasound scans (CUS) between birth and term age. In this post-hoc analysis we present a detailed analysis of the CUS data of this trial and evaluate the effect of postnatal rhIGF-1/rhIGFBP-3 replacement on the incidence of different kinds of brain injury in extremely preterm infants. Methods: This report is an exploratory post-hoc analysis of a phase II trial in which infants <28 weeks gestational age were randomly allocated to rhIGF-1/rhIGFBP-3 or SOC. Serial cranial ultrasounds were performed between birth and term-equivalent age. Presence of germinal matrix hemorrhage and intraventricular hemorrhage (GMH-IVH), periventricular hemorrhagic infarction (PHI), post-hemorrhagic ventricular dilatation, and white matter injury (WMI) were scored by two independent masked readers. Results: The analysis included 117 infants; 58 received rhIGF-1/rhIGFBP-3 and 59 received SOC. A trend toward less grade II-III GMH-IVH and PHI was observed in treated infants vs. SOC. A subanalysis of infants without evidence of GMH-IVH at study entry (n = 104) showed reduced progression to GMH-IVH in treated infants (25.0% [13/52] vs. 40.4% [21/52]; not significant). No effects of rhIGF-1/rhIGFBP-3 on WMI were observed. Conclusion: The potential protective effect of rhIGF-1/rhIGFBP-3 on the occurrence of GMH-IVH/PHI appeared most pronounced in infants with no evidence of GMH-IVH at treatment start.

Development of a Retinopathy of Prematurity Activity Scale and Clinical Outcome Measures for Use in Clinical Trials

Importance

To facilitate drug and device development for neonates, the International Neonatal Consortium brings together key stakeholders, including pharmaceutical companies, practitioners, regulators, funding agencies, scientists, and families, to address the need for objective, standardized clinical trial outcome measurements to fulfill regulatory requirements. Retinopathy of prematurity (ROP) is a disease that affects preterm neonates. The current International Classification of Retinopathy of Prematurity does not take into account all of the characteristics of ROP and does not adequately discriminate small changes in disease after treatment. These factors are critical for evaluating outcomes in clinical trials.

Observations

There is need for an updated ROP acute disease activity and structure scale as well as end-stage structure and ophthalmologic outcome measures designed for use at different ages. The scale and measures, based on current diagnostic methods and treatments, could be used as a guideline for clinical intervention trials. The scale is intended to be validated against retrospective data and revised for use in future trials. An iterative revision process can be accomplished if new measures are added to clinical trials and evaluated at the end of each trial for prognostic value. The new measures would then be incorporated into a new version of the activity scale and the outcome measures revised.

Conclusions and Relevance

An ROP activity scale and outcome measures to obtain the most robust and discriminatory data for clinical trials are needed. The scales should be dynamic and modified as knowledge and imaging modalities improve and then validated using data from well-documented clinical trials. This approach is relevant to improving clinical trial data quality.

Association of Retinopathy of Prematurity With Low Levels of Arachidonic Acid: A Secondary Analysis of a Randomized Clinical Trial

Importance

Mice with oxygen-induced retinopathy fed matched diets except for ω-3 long-chain polyunsaturated fatty acids (LC-PUFAs) vs ω-6 LC-PUFAs demonstrate relative antiangiogenic and neuroprotective associations of ω-3 LC-PUFAs. However, supplementing preterm infants with LC-PUFAs has been inconsistent in reducing major preterm morbidities. However, few studies measured serum lipid levels after supplementation.

Objective

To examine the associated risk of retinopathy of prematurity (ROP) from the levels of circulating ω-3 and ω-6 LC-PUFAs.

Design, Setting, and Participants

This longitudinal clinical study was a further analysis of serum lipid levels from a randomized controlled trial cohort of 90 infants born at gestational age (GA) less than 28 weeks. From April 4, 2013, to September 22, 2015, cord blood samples, followed by venous blood samples, were obtained at birth and at 1, 7, 14, and 28 days after birth and then at postmenstrual age (PMA) 32, 36, and 40 weeks at the neonatal intensive care unit at Sahlgrenska University Hospital in Göteborg, Sweden.

Main Outcomes and Measures

Serum phospholipid fatty acids were transmethylated and measured by gas chromatography-mass spectrometry. Mann-Whitney test, logistic regression Spearman rank correlation, and receiver operating characteristic curve analysis were used to compare differences between infants with no ROP and infants who developed ROP.

Results

Serum levels from 78 infants (43 male [55%]; mean [SD] GA, 25.5 [1.4] weeks) with a known ROP outcome were evaluated. Lower area under the curve (AUC) of arachidonic acid (AA) (20:4 ω-6) was seen in infants with a later diagnosis of ROP compared with infants with no ROP in the first month of life (mean, 34.05 [95% CI, 32.10-36.00] vs 37.15 [95% CI, 34.85-39.46]; P < .05). In addition, lower levels of AA at 32 weeks' PMA were seen in infants with later severe ROP compared with in those without ROP (mean, 7.06 [95% CI, 6.60-7.52] vs 8.74 [95% CI, 7.80-9.67]; P < .001). In logistic modeling, low postnatal serum levels of AA and GA at birth identified with a sensitivity greater than 90% of infants who developed ROP.

Conclusions and Relevance

Low postnatal levels of the ω-6 LC-PUFAs (AA) are strongly associated with ROP development. Evaluating postnatal AA fraction after birth in addition to GA may be useful for ROP prediction.

Trial Registration

clinicaltrials.gov Identifier: NCT02760472.

Erythropoietin serum levels, versus anaemia as risk factors for severe retinopathy of prematurity

BACKGROUND

Preterm infants with anaemia are treated with recombinant human erythropoietin (rhEPO). It is debated whether rhEPO treatment is a risk factor for retinopathy of prematurity (ROP). We evaluated longitudinal EPO and haemoglobin levels, blood transfusions and neonatal morbidities as risk factors for severe ROP.

METHOD

This prospective study included 78 Swedish infants, born <28 weeks gestational age (GA), screened for ROP. We tested serum EPO levels on postnatal days 1, 7, 14 and 28 and at postmenstrual ages 32, 36 and 40 weeks. Haemoglobin levels and blood transfusions were recorded during postnatal weeks 1-4. Anaemia was defined as haemoglobin ≤110 g/L.

RESULTS

During postnatal week 1, infants with severe ROP requiring treatment (28%) more frequently developed anaemia (42.9% versus 8.0%, P = 0.003) and had higher mean EPO levels (postnatal day 7: 14.2 versus 10.8 mIU/mL, P = 0.003) compared to infants with no or less severe ROP not requiring treatment. In multivariable analyses, GA and anaemia during week 1 remained significant risk factors, but elevated EPO level postnatal day 7 was no longer significant.

CONCLUSIONS

Among infants born <28 weeks GA, anaemia during week 1 was a significant risk factor for severe ROP requiring treatment but not elevated EPO levels.

Pathophysiology of Diabetic Retinopathy: Contribution and Limitations of Laboratory Research

Preclinical models of diabetic retinopathy are indispensable in the drug discovery and development of new therapies. They are, however, imperfect facsimiles of diabetic retinopathy in humans. This chapter discusses the advantages, limitations, and physiological and pathological relevance of preclinical models of diabetic retinopathy. The judicious interpretation and extrapolation of data derived from these models to humans and a correspondingly greater emphasis placed on translational medical research in early-stage clinical trials are essential to more successfully inhibit the development and progression of diabetic retinopathy in the future.

Retinal Vasculature in Development and Diseases

The retina is one of the most metabolically active tissues in the body, consuming high levels of oxygen and nutrients. A well-organized ocular vascular system adapts to meet the metabolic requirements of the retina to ensure visual function. Pathological conditions affect growth of the blood vessels in the eye. Understanding the neuronal biological processes that govern retinal vascular development is of interest for translational researchers and clinicians to develop preventive and interventional therapeutics for vascular eye diseases that address early drivers of abnormal vascular growth. This review summarizes the current knowledge of the cellular and molecular processes governing both physiological and pathological retinal vascular development, which is dependent on the interaction among retinal cell populations, including neurons, glia, immune cells, and vascular endothelial cells. We also review animal models currently used for studying retinal vascular development.

Review shows that donor milk does not promote the growth and development of preterm infants as well as maternal milk

Aim

This nonsystematic review examined differences in the composition of raw maternal breastmilk and pasteurised donor milk and possible health effects on preterm infants.

Methods

We searched PubMed up to July 2018 for studies published in English that focused on four comparisons as follows: raw maternal milk versus donor milk, human milk before and after Holder pasteurisation, milk from mothers who delivered preterm and at term and milk collected during early and late lactation. We also searched for possible effects of the milk components, as well as the effects of maternal and donor milk on preterm infants’ health.

Results

Raw maternal milk contained factors involved in antioxidant and anti‐inflammatory defence, gut microbiome establishment and the maturation of immune defences, food tolerability and metabolism. Many of these factors were reduced or abolished in processed donor milk. Both maternal milk and donor milk have been associated with a reduced incidence of necrotising enterocolitis. High‐dose feeding with maternal milk during the neonatal period reportedly reduced the risk of other morbidities and promoted growth and neurodevelopment.

Conclusion

Many of the components in raw maternal breastmilk were lacking in pasteurised donor milk, which was inferior in promoting the growth and development of very preterm infants.

rhIGF-1/rhIGFBP-3 in Preterm Infants: A Phase 2 Randomized Controlled Trial

OBJECTIVE

To investigate recombinant human insulin-like growth factor 1 complexed with its binding protein (rhIGF-1/rhIGFBP-3) for the prevention of retinopathy of prematurity (ROP) and other complications of prematurity among extremely preterm infants.

STUDY DESIGN

This phase 2 trial was conducted from September 2014 to March 2016. Infants born at a gestational age of 230/7 weeks to 276/7 weeks were randomly allocated to rhIGF-1/rhIGFBP-3 (250 µg/kg/ 24 hours, continuous intravenous infusion from <24 hours of birth to postmenstrual age 296/7 weeks) or standard neonatal care, with follow-up to a postmenstrual age of 404/7 weeks. Target exposure was ≥70% IGF-1 measurements within 28-109 µg/L and ≥70% intended therapy duration. The primary endpoint was maximum severity of ROP. Secondary endpoints included time to discharge from neonatal care, bronchopulmonary dysplasia, intraventricular hemorrhage, and growth measures.

RESULTS

Overall, 61 infants were allocated to rhIGF-1/rhIGFBP-3, 60 to standard care (full analysis set); 24 of 61 treated infants achieved target exposure (evaluable set). rhIGF-1/rhIGFBP-3 did not decrease ROP severity or ROP occurrence. There was, however, a 53% decrease in severe bronchopulmonary dysplasia in the full analysis set (21.3% treated vs 44.9% standard care), and an 89% decrease in the evaluable set (4.8% vs 44.9%; P = .04 and P = .02, respectively) for severity distribution between groups. There was also a nonsignificant trend toward decrease in grades 3-4 intraventricular hemorrhage in the full analysis set (13.1% vs 23.3%) and in the evaluable set (8.3% vs 23.3%). Fatal serious adverse events were reported in 19.7% of treated infants (12/61) and 11.7% of control infants (7/60). No effect was observed on time to discharge from neonatal care/growth measures.

CONCLUSIONS

rhIGF-1/rhIGFBP-3 did not affect development of ROP, but decreased the occurrence of severe bronchopulmonary dysplasia, with a nonsignificant decrease in grades 3-4 intraventricular hemorrhage.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01096784.

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.

Long-chain polyunsaturated fatty acids decline rapidly in milk from mothers delivering extremely preterm indicating the need for supplementation

AIM

Our aim was to perform an in-depth analysis of the composition of fatty acids in milk from mothers delivering extremely preterm babies. We investigated longitudinal changes in milk fatty acid profiles and the relationship between several types of fatty acids, including omega-3 and omega-6.

METHODS

Milk samples were collected at three stages of lactation from 78 mothers who delivered at less than 28 weeks of pregnancy at the Sahlgrenska University Hospital, Gothenburg, Sweden, from April 2013 to September 2015. Fatty acid composition was analysed by gas chromatography-mass spectrometry.

RESULTS

A reduction in long-chain polyunsaturated fatty acids (LCPUFAs) was observed during the lactation period. The concentrations of arachidonic acid and docosahexaenoic acid declined from medians of 0.34 to 0.22 mol% and 0.29 to 0.15 mol%, respectively, between postnatal day 7 and a postmenstrual age of 40 weeks. Strong correlations were found between the intermediates of several classes of fatty acids, including omega-3, omega-6 and omega-9.

CONCLUSION

A rapid reduction in LCPUFA content in the mother's milk during the lactation period emphasises the importance of fatty acid supplementation to infants born extremely preterm, at least during the period corresponding to the third trimester, when rapid development of the brain and adipose tissue requires high levels of LCPUFAs.

Implementing higher oxygen saturation targets reduced the impact of poor weight gain as a predictor for retinopathy of prematurity

Aim

This study evaluated poor weight gain as a risk factor for infants who required treatment for retinopathy of prematurity (ROP), by comparing those born before and after the implementation of higher oxygen saturation (SpO₂) targets at the Queen Silvia Children's Hospital, Gothenburg, Sweden.

Methods

We compared infants born at less than 31 weeks, who were screened and, or, treated for ROP: 127 in 2011–2012 when SpO₂ targets were 88–92% and 142 in 2015–2016 when they were 91–95%. The subjects were reviewed for birth characteristics, weekly weight and ROP treatment. Data were analysed using the weight, insulin‐like growth factor 1, neonatal, ROP (WINROP) prediction tool.

Results

The 2011–2012 infants who needed ROP treatment (12.6%) had significantly poorer postnatal weight gain than those who did not, but this was not seen in the treated (17.6%) and nontreated ROP groups in 2015–2016. WINROP sensitivity decreased from 87.5% in 2011–12 to 48% in 2015–2016.

Conclusion

After the SpO₂ target range was increased from 88–92% to 91–95%, postnatal weight gain was no longer a significant risk factor and WINROP lost its ability to predict ROP requiring treatment. Risk factors clearly change as neonatal care develops.

Fibroblast Growth Factor 21 Protects Photoreceptor Function in Type 1 Diabetic Mice

Retinal neuronal abnormalities occur before vascular changes in diabetic retinopathy. Accumulating experimental evidence suggests that neurons control vascular pathology in diabetic and other neovascular retinal diseases. Therefore, normalizing neuronal activity in diabetes may prevent vascular pathology. We investigated whether fibroblast growth factor 21 (FGF21) prevented retinal neuronal dysfunction in insulin-deficient diabetic mice. We found that in diabetic neural retina, photoreceptor rather than inner retinal function was most affected and administration of the long-acting FGF21 analog PF-05231023 restored the retinal neuronal functional deficits detected by electroretinography. PF-05231023 administration protected against diabetes-induced disorganization of photoreceptor segments seen in retinal cross section with immunohistochemistry and attenuated the reduction in the thickness of photoreceptor segments measured by optical coherence tomography. PF-05231023, independent of its downstream metabolic modulator adiponectin, reduced inflammatory marker interleukin-1β (IL-1β) mRNA levels. PF-05231023 activated the AKT-nuclear factor erythroid 2-related factor 2 pathway and reduced IL-1β expression in stressed photoreceptors. PF-05231023 administration did not change retinal expression of vascular endothelial growth factor A, suggesting a novel therapeutic approach for the prevention of early diabetic retinopathy by protecting photoreceptor function in diabetes.

Influence of Human Milk and Parenteral Lipid Emulsions on Serum Fatty Acid Profiles in Extremely Preterm Infants

Background

Infants born prematurely are at risk of a deficiency in ω‐6 and ω‐3 long‐chain polyunsaturated fatty acids (LC‐PUFAs) arachidonic acid (AA) and docosahexaenoic acid (DHA). We investigated how fatty acids from breast milk and parenteral lipid emulsions shape serum LC‐PUFA profiles in extremely preterm infants during early perinatal life.

Methods

Ninety infants born < 28 weeks gestational age were randomized to receive parenteral lipids with or without the ω‐3 LC‐PUFAs eicosapentaenoic acid (EPA) and DHA (SMOFlipid: Fresenius Kabi, Uppsala, Sweden, or Clinoleic: Baxter Medical AB, Kista, Sweden, respectively). The fatty acid composition of infant serum phospholipids was determined from birth to postmenstrual age 40 weeks, and in mother's milk total lipids on postnatal day 7. Enteral and parenteral intake of LC‐PUFAs was correlated with levels in infant serum.

Results

Infants administered parenteral ω‐3 LC‐PUFAs received 4.4 and 19.3 times more DHA and EPA, respectively, over the first 2 weeks of life. Parenteral EPA but not DHA correlated with levels in infant serum. We found linear relationships between dietary EPA and DHA and infant serum levels in the Clinoleic (Baxter Medical AB) group. The volume of administered SMOFlipid (Fresenius Kabi) was inversely correlated with serum AA, whereas Clinoleic (Baxter Medical AB) inversely correlated with serum EPA and DHA.

Conclusions

There appears to be no or low correlation between the amount of DHA administered parenterally and levels measured in serum. Whether this observation reflects serum phospholipid fraction only or truly represents the amount of accreted DHA needs to be investigated. None of the parenteral lipid emulsions satisfactorily maintained high levels of both ω‐6 and ω‐3 LC‐PUFAs in infant serum.

Comparing Alternative Ranibizumab Dosages for Safety and Efficacy in Retinopathy of Prematurity: A Randomized Clinical Trial

IMPORTANCE

Anti-vascular endothelial growth factor (VEGF) therapies are a novel treatment option in retinopathy of prematurity (ROP). Data on dosing, efficacy, and safety are insufficient.

OBJECTIVE

To investigate lower doses of anti-VEGF therapy with ranibizumab, a substance with a significantly shorter systemic half-life than the standard treatment, bevacizumab.

DESIGN, SETTING, AND PARTICIPANTS

This randomized, multicenter, double-blind, investigator-initiated trial at 9 academic medical centers in Germany compared ranibizumab doses of 0.12 mg vs 0.20 mg in infants with bilateral aggressive posterior ROP; ROP stage 1 with plus disease, 2 with plus disease, or 3 with or without plus disease in zone I; or ROP stage 3 with plus disease in posterior zone II. Patients were recruited between September 2014 and August 2016. Twenty infants were screened and 19 were randomized.

INTERVENTIONS

All infants received 1 baseline ranibizumab injection per eye. Reinjections were allowed in case of ROP recurrence after at least 28 days.

MAIN OUTCOMES AND MEASURES

The primary end point was the number of infants who did not require rescue therapy at 24 weeks. Key secondary end points included time-to-event analyses, progression of physiologic vascularization, and plasma VEGF levels. Stages of ROP were photodocumented and reviewed by an expert committee.

RESULTS

Nineteen infants with ROP were enrolled (9 [47.4%] female; median [range] postmenstrual age at first treatment, 36.4 [34.7-39.7] weeks), 3 of whom died during the study (1 in the 0.12-mg group and 2 in the 0.20-mg group). Of the surviving infants, 8 (88.9%) (17 eyes [94.4%]) in the 0.12-mg group and 6 (85.7%) (13 eyes [92.9%]) in the 0.20-mg group did not require rescue therapy. Both ranibizumab doses were equally successful in controlling acute ROP (Cochran-Mantel-Haenszel analysis; odds ratio, 1.88; 95% CI, 0.26-13.49; P = .53). Physiologic intraretinal vascularization was superior in the 0.12-mg group. The VEGF plasma levels were not systematically altered in either group.

CONCLUSIONS AND RELEVANCE

This pilot study demonstrates that ranibizumab is effective in controlling acute ROP and that 24% of the standard adult dose (0.12 mg) appears equally effective as 40% (0.20 mg). Superior vascularization of the peripheral retina with 0.12 mg of ranibizumab indicates that the lower dose may be favorable. Unchanged plasma VEGF levels point toward a limited systemic drug exposure after ranibizumab.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02134457 and clinicaltrialsregister.eu Identifier: 2013-002539-13.

Relation of Retinopathy of Prematurity to Brain Volumes at Term Equivalent Age and Developmental Outcome at 2 Years of Corrected Age in Very Preterm Infants

BACKGROUND

Retinopathy of prematurity (ROP) is a major complication of preterm birth and has been associated with later visual and nonvisual impairments.

OBJECTIVES

To evaluate relationships between any stage of ROP, brain volumes, and developmental outcomes.

METHODS

This study included 52 very preterm infants (gestational age [mean ± SD]: 26.4 ± 1.9 weeks). Total brain, gray matter, unmyelinated white matter (UWMV), and cerebellar volumes were estimated in 51 out of 52 infants by magnetic resonance imaging at term-equivalent age. Bayley Scales of Infant Development were used to assess developmental outcomes in 49 out of 52 infants at a mean corrected age of 24.6 months.

RESULTS

Nineteen out of 52 infants developed any stage of ROP. Infants with ROP had a lower median (IQR) UWMV (173 [156-181] vs. 204 [186-216] mL, p < 0.001) and cerebellar volume (18.3 [16.5-20] vs. 22.3 [20.3-24.7] mL, p < 0.001) than infants without ROP. They also had a lower median (IQR) mental developmental index (72 [56-83] vs. 100 [88-104], p < 0.001) and a lower psychomotor developmental index (80 [60-85] vs. 92 [81-103], p = 0.002). Brain volumes and developmental outcomes did not differ among infants with different stages of ROP.

CONCLUSION

Any stage of ROP in preterm infants was associated with a reduced brain volume and an impaired developmental outcome. These results suggest that common pathways may lead to impaired neural and neurovascular development in the brain and retina and that all stages of ROP may be considered in future studies on ROP and development.

PPARα is essential for retinal lipid metabolism and neuronal survival

Background

Peroxisome proliferator activated receptor-alpha (PPARα) is a ubiquitously expressed nuclear receptor. The role of endogenous PPARα in retinal neuronal homeostasis is unknown. Retinal photoreceptors are the highest energy-consuming cells in the body, requiring abundant energy substrates. PPARα is a known regulator of lipid metabolism, and we hypothesized that it may regulate lipid use for oxidative phosphorylation in energetically demanding retinal neurons.

Results

We found that endogenous PPARα is essential for the maintenance and survival of retinal neurons, with Pparα^-/- mice developing retinal degeneration first detected at 8 weeks of age. Using extracellular flux analysis, we identified that PPARα mediates retinal utilization of lipids as an energy substrate, and that ablation of PPARα ultimately results in retinal bioenergetic deficiency and neurodegeneration. This may be due to PPARα regulation of lipid transporters, which facilitate the internalization of fatty acids into cell membranes and mitochondria for oxidation and ATP production.

Conclusion

We identify an endogenous role for PPARα in retinal neuronal survival and lipid metabolism, and furthermore underscore the importance of fatty acid oxidation in photoreceptor survival. We also suggest PPARα as a putative therapeutic target for age-related macular degeneration, which may be due in part to decreased mitochondrial efficiency and subsequent energetic deficits.

Electronic supplementary material

The online version of this article (doi:10.1186/s12915-017-0451-x) contains supplementary material, which is available to authorized users.

FGF21 Administration Suppresses Retinal and Choroidal Neovascularization in Mice

Pathological neovascularization, a leading cause of blindness, is seen in retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration. Using a mouse model of hypoxia-driven retinal neovascularization, we find that fibroblast growth factor 21 (FGF21) administration suppresses, and FGF21 deficiency worsens, retinal neovessel growth. The protective effect of FGF21 against neovessel growth was abolished in adiponectin (APN)-deficient mice. FGF21 administration also decreased neovascular lesions in two models of neovascular age-related macular degeneration: very-low-density lipoprotein-receptor-deficient mice with retinal angiomatous proliferation and laser-induced choroidal neovascularization. FGF21 inhibited tumor necrosis α (TNF-α) expression but did not alter Vegfa expression in neovascular eyes. These data suggest that FGF21 may be a therapeutic target for pathologic vessel growth in patients with neovascular eye diseases, including retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration.

Adiponectin Mediates Dietary Omega-3 Long-Chain Polyunsaturated Fatty Acid Protection Against Choroidal Neovascularization in Mice

Purpose

Neovascular age-related macular degeneration (AMD) is a major cause of legal blindness in the elderly. Diets with omega3-long-chain-polyunsaturated-fatty-acid (ω3-LCPUFA) correlate with a decreased risk of AMD. Dietary ω3-LCPUFA versus ω6-LCPUFA inhibits mouse ocular neovascularization, but the underlying mechanism needs further exploration. The aim of this study was to investigate if adiponectin (APN) mediated ω3-LCPUFA suppression of neovessels in AMD.

Methods

The mouse laser-induced choroidal neovascularization (CNV) model was used to mimic some of the inflammatory aspect of AMD. CNV was compared between wild-type (WT) and Apn^−/− mice fed either otherwise matched diets with 2% ω3 or 2% ω6-LCPUFAs. Vldlr^−/− mice were used to mimic some of the metabolic aspects of AMD. Choroid assay ex vivo and human retinal microvascular endothelial cell (HRMEC) proliferation assay in vitro was used to investigate the APN pathway in angiogenesis. Western blot for p-AMPKα/AMPKα and qPCR for Apn, Mmps, and IL-10 were used to define mechanism.

Results

ω3-LCPUFA intake suppressed laser-induced CNV in WT mice; suppression was abolished with APN deficiency. ω3-LCPUFA, mediated by APN, decreased mouse Mmps expression. APN deficiency decreased AMPKα phosphorylation in vivo and exacerbated choroid-sprouting ex vivo. APN pathway activation inhibited HRMEC proliferation and decreased Mmps. In Vldlr^−/− mice, ω3-LCPUFA increased retinal AdipoR1 and inhibited NV. ω3-LCPUFA decreased IL-10 but did not affect Mmps in Vldlr^−/− retinas.

Conclusions

APN in part mediated ω3-LCPUFA inhibition of neovascularization in two mouse models of AMD. Modulating the APN pathway in conjunction with a ω3-LCPUFA-enriched-diet may augment the beneficial effects of ω3-LCPUFA in AMD patients.

Cerebellar Exposure to Cell-Free Hemoglobin Following Preterm Intraventricular Hemorrhage: Causal in Cerebellar Damage?

Decreased cerebellar volume is associated with intraventricular hemorrhage (IVH) in very preterm infants and may be a principal component in neurodevelopmental impairment. Cerebellar deposition of blood products from the subarachnoid space has been suggested as a causal mechanism in cerebellar underdevelopment following IVH. Using the preterm rabbit pup IVH model, we evaluated the effects of IVH induced at E29 (3 days prior to term) on cerebellar development at term-equivalent postnatal day 0 (P0), term-equivalent postnatal day 2 (P2), and term-equivalent postnatal day 5 (P5). Furthermore, the presence of cell-free hemoglobin (Hb) in cerebellar tissue was characterized, and cell-free Hb was evaluated as a causal factor in the development of cerebellar damage following preterm IVH. IVH was associated with a decreased proliferative (Ki67-positive) portion of the external granular layer (EGL), delayed Purkinje cell maturation, and activated microglia in the cerebellar white matter. In pups with IVH, immunolabeling of the cerebellum at P0 demonstrated a widespread presence of cell-free Hb, primarily distributed in the white matter and the molecular layer. Intraventricular injection of the Hb scavenger haptoglobin (Hp) resulted in a corresponding distribution of immunolabeled Hp in the cerebellum and a partial reversal of the damaging effects observed following IVH. The results suggest that cell-free Hb is causally involved in cerebellar damage following IVH and that blocking cell-free Hb may have protective effects.

Effects of a lipid emulsion containing fish oil on polyunsaturated fatty acid profiles, growth and morbidities in extremely premature infants: A randomized controlled trial

BACKGROUND & AIMS

The purpose of the study was to compare the effects of the parenteral emulsion SMOFlipid^®, with 15% fish oil, with Clinoleic^® on retinopathy of prematurity (ROP) and other morbidities and growth, and to compare their impact on longitudinal serum levels of fatty acids. Retinopathy of prematurity, other morbidity and growth were correlated with each parenteral lipid supplement.

METHODS

Ninety infants born at gestational age <28 weeks were randomized to treatment with SMOFlipid^® or Clinoleic^®. Two thirds (66%) of the infants received parenteral nutrition for up to 14 days birth (median 8, range 2-14 days), and additional 25% of the infants received for up to 28 days after birth (median 21, range 15-28 days). Cord blood samples and then venous blood samples were obtained at ages 1, 7, 14, and 28 days and at postmenstrual age (PMA) 32, 36, and 40 weeks. Breastmilk was collected at postnatal day 7, and at PMA 32 and 40 weeks. Serum phospholipid and breastmilk total fatty acids were analyzed by gas chromatography-mass spectrometry. Treatment groups were compared with regard to ROP, bronchopulmonary dysplasia, necrotizing enterocolitis, patent ductus arteriosus sepsis and growth between birth and 36 weeks.

RESULTS

Infants on SMOFlipid^® had higher fractions of omega-3 LCPUFA eicosapentaenoic acid (EPA) and slightly higher omega-3 LCPUFA docosahexaenoic acid (DHA) fraction and a decreased arachidonic acid (AA) to DHA ratio from one week after birth up to 32 postmenstrual weeks compared to infants on Clinoleic^®. Treatment groups did not differ in morbidities or growth.

CONCLUSION

Supplementation with SMOFlipid^® containing 15% fish oil during parenteral nutrition increased EPA substantially, DHA marginally, reduced AA and decreased AA to DHA ratio. It did not reduce morbidity or affect growth. Since extremely preterm infants accumulate a large deficit of DHA and AA, studies on more prolonged or different levels of DHA and AA supplementation are warranted.

Inflammatory signals from photoreceptor modulate pathological retinal angiogenesis via c-Fos

Pathological neovessels growing into the normally avascular photoreceptors cause vision loss in many eye diseases, such as age-related macular degeneration and macular telangiectasia. Ocular neovascularization is strongly associated with inflammation, but the source of inflammatory signals and the mechanisms by which these signals regulate the disruption of avascular privilege in photoreceptors are unknown. In this study, we found that c-Fos, a master inflammatory regulator, was increased in photoreceptors in a model of pathological blood vessels invading photoreceptors: the very low-density lipoprotein receptor-deficient (Vldlr^-/- ) mouse. Increased c-Fos induced inflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor (TNF), leading to activation of signal transducer and activator of transcription 3 (STAT3) and increased TNFα-induced protein 3 (TNFAIP3) in Vldlr^-/- photoreceptors. IL-6 activated the STAT3/vascular endothelial growth factor A (VEGFA) pathway directly, and elevated TNFAIP3 suppressed SOCS3 (suppressor of cytokine signaling 3)-activated STAT3/VEGFA indirectly. Inhibition of c-Fos using photoreceptor-specific AAV (adeno-associated virus)-hRK (human rhodopsin kinase)-sh_c-fos or a chemical inhibitor substantially reduced the pathological neovascularization and rescued visual function in Vldlr^-/- mice. These findings suggested that the photoreceptor c-Fos controls blood vessel growth into the normally avascular photoreceptor layer through the inflammatory signal-induced STAT3/VEGFA pathway.