Low-Dose Parenteral Soybean Oil for the Prevention of Parenteral Nutrition-Associated Liver Disease in Neonates With Gastrointestinal Disorders.

BACKGROUND: Neonates with gastrointestinal disorders (GDs) are at high risk for parenteral nutrition-associated liver disease (PNALD). Soybean-based intravenous lipid emulsions (S-ILE) have been associated with PNALD. This study's objective was to determine if a lower dose compared with a higher dose of S-ILE prevents cholestasis without compromising growth. MATERIALS AND METHODS: This multicenter randomized controlled pilot study enrolled patients with GDs who were ≤5 days of age to a low dose (~1 g/kg/d) (LOW) or control dose of S-ILE (~3 g/kg/d) (CON). The primary outcome was cholestasis (direct bilirubin [DB] >2 mg/dL) after the first 7 days of age. Secondary outcomes included growth, PN duration, and late-onset sepsis. RESULTS: Baseline characteristics were similar between the LOW (n = 20) and CON groups (n = 16). When the LOW group was compared with the CON group, there was no difference in cholestasis (30% vs 38%, P = .7) or secondary outcomes. However, mean ± SE DB rate of change over the first 8 weeks (0.07 ± 0.04 vs 0.3 ± 0.09 mg/dL/wk, P = .01) and entire study (0.008 ± 0.03 vs 0.2 ± 0.07 mg/dL/wk, P = .02) was lower in the LOW group compared with the CON group. CONCLUSION: In neonates with GDs who received a lower dose of S-ILE, DB increased at a slower rate in comparison to neonates who received a higher dose of S-ILE. Growth was comparable between the groups. This study demonstrates a need for a larger, randomized controlled trial comparing 2 different S-ILE doses for cholestasis prevention in neonates at risk for PNALD.

Mechanism for nicotine-induced up-regulation of Wnt signaling in human alveolar interstitial fibroblasts.

Nicotine exposure alters normal homeostatic pulmonary epithelial-mesenchymal paracrine signaling pathways, resulting in alveolar interstitial fibroblast (AIF)-to-myofibroblast (MYF) transdifferentiation. Since the AIF versus MYF phenotype is determined by the expression of peroxisome proliferator-activated receptor γ (PPARγ) and Wingless/Int (Wnt) signaling, respectively, the authors hypothesized that nicotine-induced AIF-to-MYF transdifferentiation is characterized by the down-regulation of PPARγ, and the up-regulation of the Wnt signaling pathway. As nicotine is known to activate protein kinase C (PKC) signaling, the authors also hypothesized that in AIFs, nicotine-induced up-regulation of Wnt signaling might be due to PKC activation. Embryonic human lung fibroblasts (WI38 cells) were treated with nicotine (1 × 10(-6) M) for either 30 minutes or 24 hours, with or without 30-minute pretreatment with calphostin C (1 × 10(-7) M), a pan-PKC inhibitor. Then the authors examined the activation of PKC (p-PKC) and Wnt signaling (p-GSK-3ß, ß-catenin, LEF-1, and fibronectin). Furthermore, activation of nicotinic acetylcholine receptor (nAChR)-α3 and -α7 and whether a PPARγ agonist, rosiglitazone (RGZ), blocks nicotine-mediated Wnt activation were examined. Following nicotine stimulation, there was clear evidence for nAChR-α3 and -α7 up-regulation, accompanied by the activation of PKC and Wnt signaling, which was further accompanied by significant changes in the expression of the downstream targets of Wnt signaling at 24 hours. Nicotine-mediated Wnt activation was almost completely blocked by pretreatment with either calphostin C or RGZ, indicating the central involvement of PKC activation and Wnt/PPARγ interaction in nicotine-induced up-regulation of Wnt signaling, and hence AIF-to-MYF transdifferentiation, providing novel preventive/therapeutic targets for nicotine-induced lung injury.

Peroxisome proliferator-activated receptor gamma agonists enhance lung maturation in a neonatal rat model.

The nuclear transcription factor peroxisome proliferator-activated receptor (PPAR) gamma plays a central role in normal lung development. However, the effects of modulating PPARgamma expression by exogenously administered PPARgamma agonists on lung development and basic blood biochemical and metabolic profiles in a developing animal are not known. To determine these effects, newborn Sprague-Dawley rat pups were administered either diluent or rosiglitazone (RGZ), a potent PPARgamma agonist, for either 1 or 7 d. Then the pups were killed and the lungs were examined for specific markers of alveolar epithelial, mesenchymal, and vascular maturation, and lung morphometry. The effect of RGZ on a limited number of blood biochemical and metabolic parameters was also determined. Overall, systemically administered RGZ significantly enhanced lung maturation without affecting serum electrolytes, blood glucose, blood gases, plasma cholesterol, triglycerides, and serum cardiac troponin levels. The lung maturation effect of PPARgamma agonists was also confirmed by another PPARgamma agonist, the naturally occurring PPARgamma ligand prostaglandin J2. We conclude that systemically administered RGZ significantly enhances lung maturation without significantly affecting the acute blood biochemical and metabolic profiles, providing rationale for further studying PPARgamma agonists for enhancing lung maturation, and for promoting lung injury/repair in neonates.

Prevention and treatment of bronchopulmonary dysplasia: contemporary status and future outlook.

Despite tremendous advances in neonatology, bronchopulmonary dysplasia (BPD) remains a major cause of morbidity and mortality among premature infants. Any intervention that would reduce the risk of BPD or improve its outcome is likely to have substantial clinical and financial benefits. However, there is a clear lack of an effective agent for the treatment and/or prevention of BPD. This is due to an incomplete understanding of the molecular mechanisms involved in its pathogenesis. Taking a basic biological approach, our laboratory has discovered that disruption of normal alveolar homeostatic signaling is centrally involved in this process. Using a number of in vitro and in vivo models, our laboratory has demonstrated that stabilization of the normal alveolar homeostatic signaling pathway(s) can prevent and/or rescue the molecular injuries caused by the insults that lead to BPD. Here, we review the existing approaches to prevent and treat BPD and then, based on our insights into the pathogenesis of BPD, we propose novel and innovative therapeutic options that impact the disease on a cell/molecular level, unlike most of the current treatments available for BPD.

A paradoxical temporal response of the PTHrP/PPARgamma signaling pathway to lipopolysaccharide in an in vitro model of the developing rat lung.

Chorioamnionitis alters lung development, resulting in a paradoxical decrease in the incidence of respiratory distress syndrome but an increase in the incidence of bronchopulmonary dysplasia (BPD). The mechanism(s) underlying this disparity in the pulmonary outcomes is not known. We hypothesized that specific alterations in alveolar epithelial-mesenchymal interactions might explain this apparent disparity in the pulmonary outcome following chorioamnionitis. We determined the effects of lipopolysaccharide (LPS) on parathyroid hormone-related protein (PTHrP)-driven epithelial-mesenchymal interactions that are essential for normal lung development and homeostasis. Lung explants from embryonic day 19.5 Sprague-Dawley rat fetuses were treated with LPS with or without a PTHrP pathway agonist, prostaglandin J(2) (PGJ(2)). LPS treatment affected the production of proinflammatory cytokines and the expression of the key markers of the epithelial-mesenchymal paracrine interactions in a time-dependent manner. At 6 h, there was a significant increase in the expression of PTHrP and the other key markers of alveolar homeostasis without any significant effect on alpha-smooth muscle actin (alphaSMA). In contrast, at 72 h, there was a significant decrease in the expression of PTHrP and the other key markers of alveolar homeostasis accompanied by a significant increase in alphaSMA expression. The cytokine and molecular changes at 72 h were completely prevented by the concomitant treatment with PGJ(2). We speculate that these data provide a likely mechanism for the acute stimulation of lung differentiation, accompanied paradoxically by BPD following chorioamnionitis, and suggest that by specifically targeting PTHrP signaling, the inflammation-induced molecular injury that is known to result in BPD can be prevented.