Blood cytokines and BPD

Use of Azithromycin for the Prevention of Lung Injury in Mechanically Ventilated Preterm Neonates: A Randomized Controlled Trial

INTRODUCTION

Macrolides have anti-inflammatory and immunomodulatory properties that give this class of antibiotics a role that differs from its classical use as an antibiotic, which opens new therapeutic possibilities.

OBJECTIVE

The aim of this study was to evaluate the anti-inflammatory effect of azithromycin in preventing mechanical ventilation (MV)-induced lung injury in very-low-birth-weight preterm neonates.

METHODS

This is a randomized, double-blind, placebo-controlled trial of preterm neonates who received invasive MV within 72 h of birth. Patients were randomized to receive intravenous azithromycin (at a dose of 10/mg/kg/day for 5 days) or placebo (0.9% saline) within 12 h of the start of MV. Two blood samples were collected (before and after intervention) for measurement of interleukins (ILs) and PCR for Ureaplasma. Patients were followed up throughout the hospital stay for the outcomes of death and broncho-pulmonary dysplasia defined as need for oxygen for a period of ≥28 days of life (registered at ClinicalTrials.gov, No. NCT03485703).

RESULTS

Forty patients were analyzed in the azithromycin group and 40 in the placebo group. Five days after the last dose, serum IL-2 and IL-8 levels dropped significantly in the azithromycin group. There was a significant reduction in the incidence of death and O2 dependency at 28 days/death in azithromycin-treated patients regardless of the detection of Ureaplasma in blood.

CONCLUSIONS

Azithromycin has anti-inflammatory effects, with a decrease in cytokines after 5 days of use and a reduction in death and O2 dependency at 28 days/death in mechanically ventilated preterm neonates.

Bronchopulmonary dysplasia: Pathogenesis and treatment

Bronchopulmonary dysplasia (BPD) is a form of chronic lung disease of infancy, which mostly affects premature infants with significant morbidity and mortality. Premature infants who require to be treated for conditions including respiratory distress syndrome have a higher risk of developing BPD. In spite of the improvement in clinical methods, the incidence of BPD has not reduced. In the present review, the pathogenesis of BPD is described along with the treatments available at present and the role of nursing in the management of BPD. Emerging preventive therapies for BPD are also discussed, including the use of recombinant human superoxide dismutase, which has been proven effective in reducing respiratory injury and its long-term effects.

TLR Activation Alters Bone Marrow-Derived Macrophage Differentiation

Early exposure to inflammatory signals may have a lasting impact on immune function. Present throughout embryogenesis, macrophages are key cells providing innate immune protection to the developing fetus and newborn. Here, we have used an established model of macrophage development to test how early inflammatory signals can impact cellular differentiation and function. Bone marrow-derived macrophages were treated with Escherichia coli lipopolysaccharide (LPS) 2 days after initial isolation and culture. LPS treatment during this early stage of differentiation decreased the expression of CSF1R and increased that of the mature macrophage marker F4/80. These early changes in macrophage differentiation were also measured in cells from mice lacking IKKβ, but the change in CSF1R expression after LPS treatment was blocked with MAPK inhibition. LPS-induced changes in macrophage marker expression persisted following LPS removal, suggesting that early inflammatory activation could induce a lasting developmental impact. Early LPS exposure inhibited macrophage phagocytosis of labeled E. coli while LPS had no effect on fully differentiated macrophages. Our data demonstrate that early inflammatory exposure to a microbial stimulus induce lasting phenotypic changes in macrophages.

Intrauterine endotoxin-induced impairs pulmonary vascular function and right ventricular performance in infant rats and improvement with early vitamin D therapy

High pulmonary vascular resistance (PVR), proximal pulmonary artery (PA) impedance, and right ventricular (RV) afterload due to remodeling contribute to the pathogenesis and severity of pulmonary hypertension (PH). Intra-amniotic exposure to endotoxin (ETX) causes sustained PH and high mortality in rat pups at birth, which are associated with impaired vascular growth and RV hypertrophy in survivors. Treatment of ETX-exposed pups with antenatal vitamin D (vit D) improves survival and lung growth, but the effects of ETX exposure on RV-PA coupling in the neonatal lung are unknown. We hypothesized that intrauterine ETX impairs RV-PA coupling through sustained abnormalities of PA stiffening and RV performance that are attenuated with vit D therapy. Fetal rats were exposed to intra-amniotic injections of ETX, ETX+vit D, or saline at 20 days gestation (term = 22 days). At postnatal day 14, pups had pressure-volume measurements of the RV and isolated proximal PA, respectively. Lung homogenates were assayed for extracellular matrix (ECM) composition by Western blot. We found that ETX lungs contain decreased α-elastin, lysyl oxidase, collagen I, and collagen III proteins (P < 0.05) compared control and ETX+vit D lungs. ETX-exposed animals have increased RV mechanical stroke work (P < 0.05 vs. control and ETX+vit D) and elastic potential energy (P < 0.05 vs. control and ETX+vit D). Mechanical stiffness and ECM remodeling are increased in the PA (P < 0.05 vs. control and ETX+vit D). We conclude that intrauterine exposure of fetal rats to ETX during late gestation causes persistent impairment of RV-PA coupling throughout infancy that can be prevented with early vit D treatment.

Vitamin D treatment improves survival and infant lung structure after intra-amniotic endotoxin exposure in rats: potential role for the prevention of bronchopulmonary dysplasia

Vitamin D (vit D) has anti-inflammatory properties and modulates lung growth, but whether vit D can prevent lung injury after exposure to antenatal inflammation is unknown. We hypothesized that early and sustained vit D treatment could improve survival and preserve lung growth in an experimental model of bronchopulmonary dysplasia induced by antenatal exposure to endotoxin (ETX). Fetal rats (E20) were exposed to ETX (10 μg), ETX + Vit D (1 ng/ml), or saline (control) via intra-amniotic (IA) injections and delivered 2 days later. Newborn pups exposed to IA ETX received daily intraperitoneal injections of vit D (1 ng/g) or saline for 14 days. Vit D treatment improved oxygen saturations (78 vs. 87%; P < 0.001) and postnatal survival (84% vs. 57%; P < 0.001) after exposure to IA ETX compared with IA ETX alone. Postnatal vit D treatment improved alveolar and vascular growth at 14 days by 45% and 25%, respectively (P < 0.05). Vit D increased fetal sheep pulmonary artery endothelial cell (PAEC) growth and tube formation by 64% and 44%, respectively (P < 0.001), and prevented ETX-induced reductions of PAEC growth and tube formation. Vit D directly increased fetal alveolar type II cell (ATIIC) growth by 26% (P < 0.001) and enhanced ATIIC growth in the presence of ETX-induced growth suppression by 73% (P < 0.001). We conclude that antenatal vit D therapy improved oxygenation and survival in newborn rat pups and enhanced late lung structure after exposure to IA ETX in vivo, which may partly be due to direct effects on vascular and alveolar growth.

Frontiers in pulmonary hypertension in infants and children with bronchopulmonary dysplasia

Pulmonary hypertension (PH) is an increasingly recognized complication of premature birth and bronchopulmonary dysplasia (BPD), and is associated with increased morbidity and mortality. Extreme phenotypic variability exists among preterm infants of similar gestational ages, making it difficult to predict which infants are at increased risk for developing PH. Intrauterine growth retardation or drug exposures, postnatal therapy with prolonged positive pressure ventilation, cardiovascular shunts, poor postnatal lung and somatic growth, and genetic or epigenetic factors may all contribute to the development of PH in preterm infants with BPD. In addition to the variability of severity of PH, there is also qualitative variability seen in PH, such as the variable responses to vasoactive medications. To reduce the morbidity and mortality associated with PH, a multi-pronged approach is needed. First, improved screening for and increased recognition of PH may allow for earlier treatment and better clinical outcomes. Second, identification of both prenatal and postnatal risk factors for the development of PH may allow targeting of therapy and resources for those at highest risk. Third, understanding the pathophysiology of the preterm pulmonary vascular bed may help improve outcomes through recognizing pathways that are dysregulated in PH, identifying novel biomarkers, and testing novel treatments. Finally, the recognition of conditions and exposures that may exacerbate or lead to recurrent PH is needed to help with developing treatment guidelines and preventative strategies that can be used to reduce the burden of disease.

Neonatal hyperoxia contributes additively to cigarette smoke-induced chronic obstructive pulmonary disease changes in adult mice

The extent by which early postnatal lung injury contributes to the development of chronic obstructive pulmonary disease (COPD) in the adult is unclear. We hypothesized that exposure to hyperoxia during early postnatal life can augment lung changes caused by adult chronic cigarette smoke (CS) exposure. C57BL/6J mice (1 d old) were exposed to hyperoxia (O(2)) for 5 days. At 1 month of age, half of the O(2)-exposed mice and half of the control mice were placed in a CS chamber for 6 months. After exposure to CS, mice underwent quasi-static pressure-volume curve and mean chord length measurements; quantification of pro-Sp-c expression; and measurement of lung IL-8/ KC, CXCR2/IL8Rα, TNF-α, and IL-6 mRNA by real-time PCR. Adult mice exposed to O(2)+CS had significantly larger chord length measurements (P < 0.02) and lung volumes at 35 cm H(2)O (P < 0.05) compared with all other groups. They also had significantly less pro-Sp-c protein and surfactant protein C mRNA expression (P < 0.003). Mice exposed to O(2)+CS and CS-only mice had significantly higher lung resistance and longer mean time constants (P < 0.01), significantly more inflammatory cells in the bronchoalveolar lavage fluid (P < 0.03), and significantly higher levels of lung CXCR2/IL8Rα mRNA compared with mice not exposed to smoke (P < 0.02). We conclude that exposure to early postnatal hyperoxia contributed additively to CS-induced COPD changes in adult mice. These results may be relevant to a growing population of preterm children who sustained lung injury in the newborn period and may be exposed to CS in later life.

Pathogenesis and treatment of bronchopulmonary dysplasia

PURPOSE OF REVIEW

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of infancy affecting mostly premature infants with significant morbidity and mortality. Improved survival of very immature infants has led to increased numbers of infants with this disorder. Acute and chronic lung injury and impaired postnatal lung growth are thought to be responsible for the development of BPD. Whereas changes in clinical practice have improved the clinical course and outcomes for infants with BPD, over the past decade, the overall incidence of BPD has not changed. This review will describe the prenatal and postnatal factors that contribute to the pathogenesis of BPD as well as current and experimental therapies for treatment of BPD.

RECENT FINDINGS

The factors that contribute to the pathogenesis of BPD are well described; however, recent studies have better defined how these factors modulate lung growth. Inflammation, proinflammatory cytokines and altered angiogenic gene signaling contribute to lung injury and impair prenatal and postnatal lung growth resulting in BPD; however, to date no therapy has been identified that potently and consistently prevents or reverses their effects on lung growth. We will discuss the cell signaling pathways affected in BPD and current therapies available for modulating these pathways.

SUMMARY

Despite current advances in neonatal care, BPD remains a heavy burden on healthcare resources. New treatments directed at either reducing lung injury or improving lung growth are under study.

Mechanical ventilation of newborns infant changes in plasma pro- and anti-inflammatory cytokines

OBJECTIVE

To evaluate plasma levels of interleukin (IL)-1beta, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF)-alpha in newborn infants immediately before and after 2 hours of mechanical ventilation.

STUDY DESIGN

Term and late preterm neonates with no history of mechanical ventilation and/or ventilatory support were studied prospectively. Exclusion criteria were congenital malformations, congenital infections, use of nitric oxide, resuscitation with positive-pressure ventilation, and any procedure in the delivery room or neonatal intensive care unit that resulted in tracheal intubation. Blood samples for IL-1beta, IL-6, IL-8, IL-10, and TNF-alpha levels were collected before intubation and mechanical ventilation and 2 hours later.

RESULTS

Nineteen newborn infants with gestational age 35.8 +/- 1.9 weeks and birth weight 2280 +/- 370 g were included. Pro-inflammatory cytokines increased: IL-8 (2.5-fold), IL-1beta (7.5-fold), and TNF-alpha (10-fold), and the anti-inflammatory cytokine IL-10 decreased by 90%. Although median IL-6 levels were similar between before and after ventilation, IL-6 increased in 89.4% of infants.

CONCLUSIONS

A short period of mechanical ventilation promotes an imbalance of plasma levels of pro-inflammatory and anti-inflammatory cytokines. The systemic alteration of cytokines in response to mechanical ventilation may lead to ventilator-induced lung injury.