Monocytic/macrophagic pneumonitis after intrabronchial deposition of vascular endothelial growth factor in neonatal lambs

Low Serum Vascular Endothelial Growth Factor Level Predicts Adverse Outcomes in Neonates with Respiratory Distress Syndrome

Objective: Preterm neonates are susceptible to neonatal respiratory distress syndrome (NRDS). Lower levels of cord blood vascular endothelial growth factor (VEGF) are implicated in NRDS. This study aims to explore whether the serum VEGF level has prognostic values on neonates with respiratory distress syndrome (RDS). Methods: A total of 80 infants diagnosed with NRDS were enrolled, with 70 preterm neonates without NRDS as controls. Cord blood samples before treatment and venous blood samples after treatment were collected and clinical information was recorded. The serum VEGF level was measured using enzyme-linked immunosorbent assay kits. Receiver operating characteristic (ROC) curve was used to evaluate whether serum VEGF is a biomarker of NRDS. Newborns were followed up for 1 month to collect survival information. The influence of VEGF levels on overall survival was analyzed using the Kaplan-Meier method. The univariate and multivariate Cox regression models were adopted to assess the prognostic factor of NRDS. Results: VEGF level was decreased in sera of neonates with RDS. The area under the ROC curve of VEGF level in distinguishing neonates with RDS from neonates without RDS was 0.949, with a cutoff value of 39.72 (87.50% sensitivity, 87.14% specificity). Serum VEGF was a biomarker of NRDS. Neonates with RDS with high VEGF levels had longer periods of survival than those with low VEGF levels. NRDS grade and VEGF level were independent prognostic factors affecting the overall survival of neonates with RDS. Conclusion: Decreased serum VEGF level in RDS neonates can predict the poor prognosis of NRDS, and VEGF level might be an independent prognostic factor for the overall survival of RDS neonates. Clinical Trial Registration No. 201901A.

A model of respiratory syncytial virus (RSV) infection of infants in newborn lambs

Many animal models have been established for respiratory syncytial virus (RSV) infection of infants with the purpose of studying the pathogenesis, immunological response, and pharmaceutical testing and the objective of finding novel therapies and preventive measures. This review centers on a neonatal lamb model of RSV infection that has similarities to RSV infection of infants. It includes a comprehensive description of anatomical and immunological similarities between ovine and human lungs along with comparison of pulmonary changes and immune responses with RSV infection. These features make the newborn lamb an effective model for investigating key aspects of RSV infection in infants. The importance of RSV lamb model application in preclinical therapeutic trials and current updates on new studies with the RSV-infected neonatal lamb are also highlighted.

Difference in the Vitreal Protein Profiles of Patients with Proliferative Diabetic Retinopathy with and without Intravitreal Conbercept Injection

Purpose

To examine the difference in the vitreal protein profiles of patients with proliferative diabetic retinopathy (PDR) with and without preoperative intravitreal conbercept (IVC) treatment.

Methods

Liquid chromatography-tandem mass spectrometry- (LC-MS/MS-) based proteomic methods were used to determine the protein profiles of the vitreous humor in patients with PDR treated with (IVC group; n = 9) and without (PDR group; n = 8) preoperative IVC. Gene ontology (GO) annotation and REACTOME pathway analysis were obtained to overview differentially expressed proteins between each group. Intravitreal levels of apolipoprotein A-II (APOA2) and ceruloplasmin (CP) were measured using enzyme-linked immunosorbent assays.

Results

307 proteins were expressed differentially between PDR and IVC groups, including 218 proteins downregulated in response to IVC. The most notable GO annotations in level 3 and REACTOME pathways describing the differentially expressed proteins were “innate immune response” and “platelet degranulation.” The intravitreal levels of APOA2 and CP were lower in the IVC group than in the PDR group (p < 0.01).

Conclusions

In addition to decreasing the intravitreal vascular endothelial growth factor level, IVC may alter the vitreal protein profile in patients with PDR, with the differentially regulated proteins involved in the immune response, platelet degranulation, complement activation, and inflammation.

Oxidative Stress Related Diseases in Newborns

We review oxidative stress-related newborn disease and the mechanism of oxidative damage. In addition, we outline diagnostic and therapeutic strategies and future directions. Many reports have defined oxidative stress as an imbalance between an enhanced reactive oxygen/nitrogen species and the lack of protective ability of antioxidants. From that point of view, free radical-induced damage caused by oxidative stress seems to be a probable contributing factor to the pathogenesis of many newborn diseases, such as respiratory distress syndrome, bronchopulmonary dysplasia, periventricular leukomalacia, necrotizing enterocolitis, patent ductus arteriosus, and retinopathy of prematurity. We share the hope that the new understanding of the concept of oxidative stress and its relation to newborn diseases that has been made possible by new diagnostic techniques will throw light on the treatment of those diseases.

Structural and molecular regulation of lung maturation by intratracheal vascular endothelial growth factor administration in the normally grown and placentally restricted fetus

Inhibition of hypoxia signalling leads to respiratory distress syndrome (RDS), whereas administration of vascular endothelial growth factor (VEGF), the most widely characterized hypoxia responsive factor, protects from RDS. In the lung of the chronically hypoxaemic placentally restricted (PR) fetus, there is altered regulation of hypoxia signalling. This leads to reduced surfactant maturation in late gestation and provides evidence for the increased risk of RDS in growth restricted neonates at birth. We evaluated the effect of recombinant human VEGF administration with respect to bypassing the endogenous regulation of hypoxia signalling in the lung of the normally grown and PR sheep fetus. There was no effect of VEGF administration on fetal blood pressure or fetal breathing movements. We examined the effect on the expression of genes regulating VEGF signalling (FLT1 and KDR), angiogenesis (ANGPT1, AQP1, ADM), alveolarization (MMP2, MMP9, TIMP1, COL1A1, ELN), proliferation (IGF1, IGF2, IGF1R, MKI67, PCNA), inflammation (CCL2, CCL4, IL1B, TNFA, TGFB1, IL10) and surfactant maturation (SFTP-A, SFTP-B, SFTP-C, SFTP-D, PCYT1A, LPCAT, LAMP3, ABCA3). Despite the effects of PR on the expression of genes regulating airway remodelling, inflammatory signalling and surfactant maturation, there were very few effects of VEGF administration on gene expression in the lung of both the normally grown and PR fetus. There were, however, positive effects of VEGF administration on percentage tissue, air space and numerical density of SFTP-B positive alveolar epithelial cells in fetal lung tissue. These results provide evidence for the stimulatory effects of VEGF administration on structural maturation in the lung of both the normally grown and PR fetus.

Lamb model of respiratory syncytial virus-associated lung disease: insights to pathogenesis and novel treatments

Preterm birth is a risk factor for respiratory syncytial virus (RSV) bronchiolitis and hospitalization. The pathogenesis underlying this is not fully understood, and in vivo studies are needed to better clarify essential cellular features and molecular mechanisms. Such studies include analysis of lung tissue from affected human infants and various animal models. The preterm and newborn lamb lung has developmental, structural, cellular, physiologic, and immunologic features similar to that of human infants. Also, the lamb lung is susceptible to various strains of RSV that infect infants and cause similar bronchiolar lesions. Studies in lambs suggest that viral replication in airways (especially bronchioles) is extensive by 4 days after infection, along with bronchiolitis characterized by degeneration and necrosis of epithelial cells, syncytial cell formation, neutrophil infiltration, epithelial cell hypertrophy and hyperplasia, and innate and adaptive immune responses. RSV bronchiolitis greatly affects airflow and gaseous exchange. RSV disease severity is increased in preterm lambs compared with full-term lambs; similar to human infants. The lamb is conducive to experimental assessment of novel, mechanistic therapeutic interventions such as delivery of vascular endothelial growth factor and enhancement of airway epithelial oxidative responses, Club (Clara) cell protein 10, and synthesized compounds such as nanobodies. In contrast, exposure of the fetal ovine lung in vivo to ethanol, a risk factor for preterm birth, reduces pulmonary alveolar development and surfactant protein A expression. Because the formalin-inactivated RSV vaccination enhances some inflammatory responses to RSV infection in lambs, this model has the potential to assess mechanisms of formalin-inactivated RSV enhanced disease as well as newly developed vaccines.

Oxidative stress in neonatology: a review

Free radicals are highly reactive oxidizing agents containing one or more unpaired electrons. Both in human and veterinary neonathology, it is generally accepted that oxidative stress functions as an important catalysator of neonatal disease. Soon after birth, many sudden physiological and environmental conditions make the newborn vulnerable for the negative effects of oxidative stress, which potentially can impair neonatal vitality. As a clinician, it is important to have in depth knowledge about factors affecting maternal/neonatal oxidative status and the cascades of events that enrol when the neonate is subjected to oxidative stress. This report aims at providing clinicians with an up-to-date review about oxidative stress in neonates across animal species. It will be emphasized which handlings and treatments that are applied during neonatal care or resuscitation can actually impose oxidative stress upon the neonate. Views and opinions about maternal and/or neonatal antioxydative therapy will be shared.

Exogenous administration of vascular endothelial growth factor prior to human respiratory syncytial virus a2 infection reduces pulmonary pathology in neonatal lambs and alters epithelial innate immune responses

Human respiratory syncytial virus (RSV) affects thousands of children every year. Vascular endothelial growth factor (VEGF) is a regulator of vasculogenesis, pulmonary maturation, and immunity. In order to test the extent to which VEGF may alter RSV infection, 4 groups of lambs received either human recombinant VEGF (rhVEGF) or phosphate-buffered saline (PBS) pretreatment followed by inoculation with human RSV strain A2 or sterile medium. Lambs in each group were sacrificed at 2, 4, and 6 days post infection. Expression of surfactant protein-A (SP-A), surfactant protein-D (SP-D), sheep β-defensin-1 (SBD-1), tumor necrosis factor α (TNFα), interleukin (IL)-6, IL-8, interferon β, and endogenous VEGF were measured to determine effect of rhVEGF pretreatment. RSV lambs pretreated with rhVEGF had reduced viral mRNA and decreased pulmonary pathology at day 6. Pretreatment with rhVEGF increased mRNA expression of SP-A, SBD-1, and TNFα, with alteration of expression in RSV lambs. Endogenous VEGF mRNA levels were increased at day 2 regardless of pretreatment. Pretreatment with rhVEGF increased pulmonary cellular proliferation in RSV lambs at day 4 post infection. Overall, these results suggest that pretreatment with rhVEGF protein may have therapeutic potential to decrease RSV viral load, decrease pulmonary lesion severity, and alter both epithelial innate immune responses and epithelial cell proliferation.

Effects of nicotine on pulmonary surfactant proteins A and D in ovine lung epithelia

Maternal smoking during pregnancy increases the incidence and severity of respiratory infections in neonates. Surfactant proteins A and D (SP-A and SP-D, respectively) are components of pulmonary innate immunity and have an important role in defense against inhaled pathogens. The purpose of this study was to determine if nicotine exposure during the third trimester of pregnancy alters the expression of SP-A and SP-D of fetal lung epithelia. Pregnant ewes were assigned to four groups; a nicotine-exposed full-term and pre-term group, and control full-term and pre-term group. Lung tissue was collected for Western blot and IHC analysis of SP-A level, Western blot analysis of SP-D level and qPCR analysis of SP-A and SP-D mRNA expression. Exposure to nicotine significantly decreased SP-A gene expression (P = 0.01) and SP-A protein level in pre-term lambs. This finding suggests that maternal nicotine exposure during the last trimester of pregnancy alters a key component of lung innate immunity in offspring.

Gene profiling studies in the neonatal ovine lung show enhancing effects of VEGF on the immune response

Preterm and young neonates have an increased predisposition to respiratory distress syndrome (RDS) associated with an immature development of lung surfactant. Glucocorticoids (GCs) are the major immunomodulatory agents used to increase lung development and reduce the mortality and morbidity of preterm infants with RDS. However, their safety remains uncertain, and the precise mechanisms by which they improve lung function are unclear. In previous studies, we found that vascular endothelial growth factor (VEGF) enhances the innate immune response by respiratory epithelial cells, causes a monocytic infiltration into the lung, and reduces the severity of infection by respiratory syncytial virus (RSV), a respiratory pathogen known to affect preterm infants at a high prevalence. The purpose of this study is to measure the effects of VEGF administration on local immune responses in neonatal lambs, as the ovine lung is well suited for comparison to the human lung, due to similarities in alveolar development, immune responses, and RSV susceptibility. We hypothesized that VEGF induces the expression of genes necessary for host immune responses. We analyzed global gene expression profiles in the lungs of neonate lambs treated with VEGF by real-time qPCR. We report that VEGF induced the expression of chemokines (IL-8, RANTES, MCP-1), cytokines (IFN-gamma, IL-6, TNF-alpha, GMCSF), Toll-like receptor (TLR)-4, complement family members (C3, CFB, CFH) and collectins (SP-A, SP-D). These results suggest that VEGF can regulate local immune gene expression in vivo and should be further explored as a potential exogenous therapy for various lung diseases.

Pretreatment with recombinant human vascular endothelial growth factor reduces virus replication and inflammation in a perinatal lamb model of respiratory syncytial virus infection

Vascular endothelial growth factor (VEGF) is increasingly recognized as a perinatal regulator of lung maturation and surfactant protein expression. Preterm and young infants are at increased risk for pulmonary immaturity characterized by insufficient surfactant production as well as increased risk for severe manifestations of respiratory syncytial virus (RSV) infection. Innate immune components including surfactant proteins A and D, and beta-defensins have putative antimicrobial activity against pulmonary pathogens including RSV. Our hypothesis was that recombinant human VEGF (rhVEGF) pretreatment therapy would decrease RSV disease in the perinatal lamb RSV model. Newborn lambs were pretreated with rhVEGF, betamethasone, or saline and then inoculated with bovine RSV or sterile medium. Tissues were collected 5 d postinoculation, corresponding to the initiation of severe lesions and peak viral replication. In RSV-infected lambs, rhVEGF therapy increased the mean daily body temperature, decreased airway neutrophil exudate, and reduced RSV replication compared with betamethasone or saline pretreatment. Furthermore, rhVEGF therapy significantly mitigated the RSV-induced increase in surfactant protein A mRNA expression and decrease in surfactant protein D mRNA expression. In control (non-RSV-infected) lambs, pretreatment with rhVEGF increased sheep beta-defensin-1 (SBD1) mRNA expression, but no alteration in surfactant proteins A and D was detected. This novel study demonstrates that rhVEGF pretreatment mitigates RSV disease and, in addition, rhVEGF regulation of innate immune genes is dependent on RSV infection status.