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The onset and degree of injury occurring in animals that develop hyperoxic acute lung injury (HALI) is dependent on age at exposure, suggesting that developmentally regulated pathways/factors must underlie initiation of the epithelial injury and subsequent repair. Type II TGFβ receptor interacting protein‐1 (TRIP‐1) is a negative regulator of TGFβ signaling, which we have previously shown is a developmentally regulated protein with modulatory effects on epithelial‐fibroblastic signaling. The aim of this study was to assess if type II alveolar epithelial cells overexpressing TRIP‐1 are protected against hyperoxia‐induced epithelial injury, and in turn HALI. Rat lung epithelial cells (RLE) overexpressing TRIP‐1 or LacZ were exposed to 85% oxygen for 4 days. A surfactant protein C (SPC)‐driven TRIP‐1 overexpression mouse (TRIP‐1 AECTg+ ) was generated and exposed to hyperoxia (>95% for 4 days) at 4 weeks of age to assess the effects TRIP‐1 overexpression has on HALI. RLE overexpressing TRIP‐1 resisted hyperoxia‐induced apoptosis. Mice overexpressing TRIP‐1 in their lung type II alveolar epithelial cells (TRIP‐1 AECTg+ ) showed normal lung development, increased phospho‐AKT level and E‐cadherin, along with resistance to HALI, as evidence by less TGFβ activation, apoptosis, alveolar macrophage influx, KC expression. Taken together, these findings point to existence of a TRIP‐1 mediated molecular pathway affording protection against epithelial/acute lung injury.

Epithelial-mesenchymal transition (EMT) is a process by which epithelial cells undergo conversion to a mesenchymal phenotype contributing to wound repair by fibrosis and to cancer cell acquisition of invasive ability. Recently, we showed that type II TGF-β receptor interacting protein-1 (TRIP-1), a protein identified as a phosphorylation target of the TGF-β type II receptor kinase and as a functional component of eukaryotic translation initiator factor 3 (eiF3) multiprotein complex, is a novel modulator of fibroblast collagen contraction, an important step in wound repair stimulated by TGF-β1 action. TGF-β1 drives EMT, but it is not known whether TRIP-1 expression influences EMT induction. To investigate whether TRIP-1 plays a role in EMT induction we studied the effect of downregulating TRIP-1 expression in the well-characterized A549 model of TGF-β1 induction of EMT. Here we report that short hairpin RNA (shRNA)-mediated depletion of TRIP-1 gene transcripts in A549 cells promotes EMT as assessed by changes in phenotypic markers, morphology, and migrative ability. Knockdown of TRIP-1 dramatically increased A549 responsiveness to TGF-β1 induction of EMT. Mechanistically, a pathway involving increased TGF-β type II receptor level, enhanced Smad3 phosphorylation, and the transcription factor SLUG is implicated. Altogether, the findings point to regulation of endogenous TRIP-1 protein expression as a potential strategy to target EMT, and related invasive behavior, in cancer cells.

It is unclear how sublethal hypoxia affects lung development. To investigate the effects of chronic hypoxia on postnatal lung remodeling, we treated neonatal rats with FIO2 of 0.12 for 10 d and analyzed lung development by morphometry and gene expression by DNA microarray. Our results showed the neonatal rats exposed to hypoxia reduced body weight by 42% and wet lung weight by 32% compared with the neonatal rats exposed to normoxia. In the neonatal rats exposed to hypoxia, the radial alveolar counts were decreased to 5.6 from 7.9 and the mean linear intercepts were increased to 56.5 mum from 38.2 mum. In DNA microarray analysis, approximately half of probed genes were unknown. Chronic hypoxia significantly regulated expression of genes that are involved in pathogenesis of pulmonary hypertension and postnatal lung remodeling. Chemokine ligand 12, jagged 2 were among those upregulated; c-kit, ephrin A1, and Hif-2alpha were among those downregulated. The altered expression of those genes was correlated with the lung development and remodeling.

Background: Hyperoxia and tidal volume mechanical ventilation are independent factors in the genesis of lung injury, but it remains unclear the extent to which each is responsible or contributes to this process in newborns. Objectives: To study the independent and combined effects of hyperoxia and tidal volume mechanical ventilation on the induction of lung inflammation in a newborn piglet model of ventilator-induced lung injury. Methods: Following exposure to either ambient air or FIO2 = 1.0 for a period of 3 days, newborn piglets were randomized to receive mechanical ventilation with either high tidal volume (20 ml/kg) or low tidal volume (6 ml/kg) for 4 h while controlling for pH. Results: Monocyte chemoattractant protein-1 level in the lungs of animals randomized to hyperoxia with high tidal volume ventilation was significantly elevated, compared to all other groups (p < 0.05). Myeloperoxidase assayed in lung homogenate was found to be significantly higher in nonventilated animals exposed to hyperoxia (p < 0.01). Only in animals previously exposed to hyperoxia did the addition of high tidal volume ventilation further increase the level of myeloperoxidase present (p < 0.05). Pulmonary vascular resistance was significantly elevated after 4 h of mechanical ventilation compared to 1 h (p < 0.001). Conclusions: We conclude that in neonatal piglets undergoing hyperoxic stress, superimposition of high tidal volume ventilation exacerbates the lung inflammation as assessed by lung monocyte chemoattractant protein-1 and level of myeloperoxidase.

The peptides platelet-derived growth factor-A (PDGF-A) and especially -B have important roles in lung development. The effect of hyperoxic exposure with and without inhaled nitric oxide (iNO) on lung expression of PDGF and its receptors is unknown. We hypothesized that hyperoxia exposure would suppress mRNA expression and protein production of these ligands and their receptors. The addition of iNO to hyperoxia may further aggravate the effects of hyperoxia. Thirteen-day-old piglets were randomized to breathe 1) room air (RA); 2) 0.96 fraction of inspired oxygen (O2), or 3) 0.96 fraction of inspired oxygen plus 50 ppm of NO (O2+NO), for 5 d. Lungs were preserved for mRNA, Western immunoblot, and immunohistochemical analyses for PDGF-A and -B and their receptors PDGFR-alpha and -beta. PDGF-B mRNA expression was greater than that of PDGF-A or PDGFR-alpha and -beta in RA piglet lungs (p0.05). Hyperoxia with or without iNO reduced lung PDGF-B mRNA and protein expression relative to the RA group lungs (p0.01). PDGF-B immunostain intensity was significantly increased in the alveolar macrophages, which were present in greater numbers in the hyperoxia-exposed piglet lungs, with or without NO (p0.01). PDGFR-beta immunostaining was significantly increased in airway epithelial cells in O2- and O2+NO-exposed piglets. PDGF-A and PDGFR-alpha immunostain intensity and distribution pattern were unchanged relative to the RA group. Sublethal hyperoxia decreases PDGF-B mRNA and protein expression but not PDGF-A or their receptors in piglet lungs. iNO neither aggravates nor ameliorates this effect.

In this retrospective study, we tested the following hypotheses: rates of severe intraventricular hemorrhage (SIVH) and early neonatal survival are similar among extremely low birth weight (ELBW) infants treated with combination prophylaxis of phenobarbital and indomethacin compared with phenobarbital alone or no prophylaxis; and rates of patent ductus arteriosus (PDA) and necrotizing enterocolitis (NEC) are similar among indomethacin-exposed and nonexposed ELBW infants. Data were abstracted on 265 ELBW infants admitted into a level 3 neonatal intensive care unit from 1994 through 2002. Combination prophylaxis neither reduced the odds ratio (OR) of SIVH (OR = 1.53; 95% confidence interval [CI], 0.43 to 1.16) versus phenobarbital (OR = 2.91; 95% CI, 0.91 to 9.27 versus none (OR = 1; 95% CI, reference) nor increased the odds of early neonatal survival (OR = 0.72; 95% CI, 0.17 to 3.09 for combination prophylaxis versus OR = 0.66; 95% CI, 0.16 to 2.67 for phenobarbital versus OR = 1; 95% CI, reference for none). Indomethacin exposure reduced the odds of PDA (OR = 0.35; 95% CI, 0.17 to 0.75) without increasing the risk of NEC (OR = 1.37; 95% CI, 0.60 to 3.12). In conclusion, combination prophylaxis does not improve SIVH and early neonatal survival outcomes. Early exposure to indomethacin offers some benefits without any added risks.

Objective. The pathogenesis of chronic lung disease (CLD) involves inflammation with proteolytic damage to lung extracellular matrix. Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that, acting in concert with their tissue inhibitors, tightly orchestrate extracellular matrix morphogenesis and repair after injury. Imbalances in their levels relative to that of their inhibitors have been implicated in diseases characterized by matrix disruption and remodeling. We investigated the possibility that imbalances in MMP-9 and MMP-2 relative to their tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2, respectively, in tracheal aspirates of preterm infants may be involved in the development of CLD.Methods. Serial tracheal aspirates collected from birth until extubation in 49 ventilated preterm infants (24-32 weeks’ gestations) were analyzed for MMP-2, MMP-9, TIMP-1, and TIMP-2. Data normalized by TA values of free secretory component of immunoglobulin A were compared for CLD (n = 22) versus no CLD (n = 27). Also, known clinical predictors of CLD (gestational age, birth weight, and sex) were assessed for both groups. Association of predictors with the outcome CLD was assessed by logistic regression.Results. Mean gestational age was lower in CLD infants, but birth weight and gender were comparable for both groups. CLD infants had significantly lower TIMP-1 level with higher MMP-9/TIMP-1 ratio during the first 2 weeks of life and low TIMP-2 and MMP-2 levels during the first 3 days of life compared with no-CLD infants. Logistic regression analysis indicated that the findings are predictive of CLD.Conclusions. We conclude that low tracheal aspirate levels of TIMPs, with a high MMP-9/TIMP-1 ratio early in life, are associated with subsequent development of CLD.

Microvascular development is critical for normal lung maturation. The aims of this study were (1) to quantitatively and qualitatively assess lung microvascular growth in the human fetus, from 22 to 40 weeks’ gestation, and (2) to compare development in these infants to those with mild, moderate and severe chronic lung disease (CLD). Using 1- and 4-µm thick sections and electron microscopy, lungs were morphometrically assessed for surface density of distal air spaces; volume density of parenchymal vessels having an air-blood barrier (ABB); percent of distal air space wall having an ABB, and capillary loading, defined as ABB/mm2 of epithelial surface area. The percent of vessels with ABB increased in controls during development in parallel with increasing lung parenchyma. Infants with severe CLD had fewer ABBs and less capillary loading than controls up to 34 weeks’ post-conceptional age (PCA), but by 36–40 weeks, showed catch-up growth. Microvasculature vessel diameter, septal thickness, and air sac diameter at 36–40 weeks’ PCA were increased with severe CLD, and vessels were more distant from the air surface. We conclude that infants with severe CLD have both stunted secondary septation and microvascular development, but over time, the primary septal wall adapts by thinning and increasing the number of ABBs, thereby taking on the function of secondary septa.

Pulmonary hyperoxic injury manifests as widespread alveolar-epithelial and microvascular endothelial cell necrosis, resolution of which requires angiogenesis. We investigated the hypothesis that inhaled nitric oxide (iNO) and hyperoxia each decreases lung vascular endothelial growth factor (VEGF) expression but increases endostatin and that concurrent administration of both gases will show a greater effect. Piglets were randomized to breathe for 5 d room air (RA); RA + NO (RA + 50 ppm NO), O(2) (hyperoxia, F(I)O(2) >0.96), O(2) + NO, or O(2) + NO + REC (O(2) + NO plus recovery in 50% O(2) for 72 h. After the piglets were killed, we measured lung capillary leak, VEGF mRNA, VEGF, and endostatin protein in homogenates, plasma, and lavage. VEGF mRNA decreased significantly with O(2) and O(2) + NO compared with breathing RA (p < or = 0.05). VEGF protein declined in the experimental groups with a significant reduction in the recovery group compared with the RA group (p < or = 0.05). Similar but more dramatic, endostatin declined in all groups relative to the RA group (p < 0.001). Lavage fluid VEGF protein and lung capillary leak rose significantly with O(2) and O(2) + NO compared with RA, but endostatin was unchanged. At 72 h of recovery from hyperoxia, VEGF mRNA and lavage fluid VEGF but not lung VEGF protein had normalized. Hyperoxia and iNO suppresses lung endostatin expression, but iNO unlike hyperoxia alone does not alter lung VEGF production. Hyperoxia paradoxically raises lavageable VEGF levels. This latter effect and that on VEGF mRNA level but not protein is abrogated by recovery in reduced F(I)O(2) for 72 h.

Pulmonary lymphatic development in chronic lung disease (CLD) has not been investigated, and anatomy of lymphatics in human infant lungs is not well defined.Hypothesis. Pulmonary lymphatic hypoplasia is present in CLD.Method. Autopsy lung tissues of eighteen subjects gestational ages 22 to 40 weeks with and without history of respiratory morbidity were stained with monoclonal antipodoplanin and reviewed under light microscopy. Percentage of parenchyma podoplanin stained at the acinar level was determined using computerized image analysis; 9 CLD and 4 control subjects gestational ages 27 to 36 weeks were suitable for the analysis.Results. Distinct, lymphatic-specific staining with respect to other vascular structures was appreciated in all gestations. Infants with and without respiratory morbidity had comparable lymphatic distribution which extended to the alveolar ductal level. Podoplanin staining per parenchyma was increased and statistically significant in the CLD group versus controls at the alveolar ductal level (0.06% ± 0.02% versus 0.04% ± 0.01%, 95% CI −0.04% to −0.002%,P<0.03).Conclusion. Contrary to our hypothesis, the findings show that there is an increase in alveolar lymphatics in CLD. It is suggested that the findings, by expanding current knowledge of CLD pathology, may offer insight into the development of more effective therapies to tackle CLD.

Nitric oxide (NO), a pro-oxidant gas, is used with hyperoxia (O2) to treat neonatal pulmonary hypertension and recently bronchopulmonary dysplasia, but great concerns remain regarding NO’s potential toxicity. Based on reports that exposure to oxidant gases results in pulmonary extracellular matrix injury associated with elevated lavage fluid levels of extracellular matrix components, we hypothesized that inhaled NO with or without hyperoxia will have the same effect. We measured alveolar septal width, lung collagen content, lavage fluid hydroxyproline, hyaluronan and laminin levels in neonatal piglets after 5 days’ exposure to room air (RA), RA + 50 ppm NO (RA + NO), O2 (FiO2 > 0.96) or O2 + NO. Matrix metalloproteinase (MMP) activity and MMP-2 mRNA were also measured. In recovery experiments, we measured lung collagen content in piglets exposed to RA + NO or O2 + NO and then allowed to recover for 3 days. The results show that lung collagen increased 4-fold in the RA + NO piglets, the O2 and O2 + NO groups had only a 2-fold elevation relative to RA controls. Unlike the RA + NO piglets, the O2 and O2 + NO groups had more than 20-fold elevation in lung lavage fluid hydroxyproline compared to the RA group. O2 and O2 + NO also had increased lung MMP activity, extravascular water, and lavage fluid proteins. MMP-2 mRNA levels were unchanged. After 3 days’ recovery in room air, the RA + NO groups’ lung collagen had declined from 4-fold to 2-fold above the RA group values. The O2 + NO group did not decline. Alveolar septal width increased significantly only in the O2 and O2 + NO groups. We conclude that 5 days’ exposure to NO does not result in pulmonary matrix degradation but instead significantly increases lung collagen content. This effect appears potentially reversible. In contrast, hyperoxia exposure with or without NO results in pulmonary matrix degradation and increased lung collagen content. The observation that NO increased lung collagen content represents a new finding and suggests NO could potentially induce pulmonary fibrosis.

Clinical use of nitric oxide (NO) is usually in conjunction with high oxygen concentrations, the effects of which may include lung neutrophil accumulation, apoptosis and upregulation of antioxidant enzyme activity. To define the effects of NO on neutrophils from young piglets and its relationship to lung neutrophil dynamics during hyperoxia we exposed thirty piglets to room air (RA), RA+NO (50 ppm NO), O2 (FiO2≥0.96) or O2+NO for 5 days. Ten additional animals breathed RA+NO or O2+NO, then recovered in RA for 3 days before sacrifice. Neutrophil CD18 and intracellular oxidant production were measured by flow cytometry. Lung apoptosis were assessed by TUNEL assay. Lung myeloperoxidase, SOD and catalase were measured biochemically. When compared to RA group, there was significant reduction in neutrophil CD18 and intracellular oxidant production in the RA+NO group, but lung MPO was unchanged. The O2 and O2+NO groups did not differ in CD18 expression or in intracellular oxidant production, but had significant increase in lung myeloperoxidase compared to the RA group. Apoptosis increased significantly only in the O2+NO group. The O2 group showed significantly increased lung SOD and catalase activity compared to the RA group, whereas the RA+NO and O2+NO groups did not. We conclude that inhaled NO at 50 ppm decreases neutrophil CD18 expression as well as intracellular oxidant production. However, this effect does not impact lung neutrophil accumulation during concurrent hyperoxia. The combination of NO and O2 exposure produces an increase in lung apoptosis. Finally, NO may prevent upregulation of SOD and catalase activity during hyperoxia, potentially increasing injury.

Exhaled gas from mechanically ventilated preterm infants was found to have similar oxidant concentrations, regardless of lung disease, leading to the hypothesis that wall outlet gases were an oxidant source. Oxidants in compressed room air and oxygen from wall outlets were assessed in three hospitals. Samples were collected by flowing wall outlet gas through a heated humidifier and an ice-packed condenser. Nitric oxide (NO) was measured in intensive care room air and in compressed air with and without a charcoal filter using a Sievers NOA280 nitric oxide analyzer (Boulder, CO). Oxidants were measured by spectrophotometry and expressed as nMol equivalents of H2O2/mL. The quantity of oxidant was also expressed as amount of Vitamin C (nMol/mL) added until the oxidant was nondetectable. This quantity of Vitamin C was also expressed in Trolox Equivalent Antioxidant Capacity (TEAC) units (mMol/L). Free and total chlorine were measured with a Chlorine Photometer. Oxidants were not found in compressed oxygen and were only found in compressed air when the compression method used tap water. At a compressed room air gas flow of 1.5 L/min, the total volume of condensate was 20.2 +/- 1 mL/hr. The oxidant concentration was 1.52 +/- 0.09 nMol/mL equivalents of H2O2/mL of sample and 30.8 +/- 1.2 nMol/hr; 17.9% of that found in tap water. Oxidant reduction required 2.05 +/-0.12 nMol/mL vitamin C, (1.78 +/- 0.1 x 10(-3) TEAC units). Free and total chlorine in tap water were 0.3 +/- 0.02 mg/mL and 2.9 +/- 0.002 mg/mL, respectively. Outlet gas contained 0.4 +/- 0.06 mg/mL and 0.07 + 0.01 mg/mL total and free chlorine, respectively; both 14% of tap water. When a charcoal filter was installed in the hospital with oxidants in compressed air, oxidants were completely removed. Nursery room air contained 12.4 +/- 0.5 ppb NO; compressed wall air without a charcoal filter, 8.1 +/- 0.1 ppb and compressed air with a charcoal filter 12.5 +/- 0.5 ppb. A charcoal filter does not remove NO. (Table 3) We recommend that all compressed air methods using tap water have charcoal filters at the compression site and the gases be assessed periodically for oxidants.

Acute lung injury involving extremely immature lungs often heals without excessive fibrosis unlike later in gestation and in adults. Several factors may be involved, but fibroblast contraction of collagen has been linked to the level of wound fibrosis. To assess whether human lung fibroblasts of fetal versus adult origin differ in ability to contract collagen and define the molecular underpinnings, we performed three-dimensional collagen contraction assay, analyzed their differential mRNA profile, specifically for transforming growth factor-beta (TGF-beta) signaling pathway and extracellular matrix components, studied the cell response to TGF-beta in culture, and used two-dimensional gel electrophoresis followed by mass spectrometry to identify differences in their overall proteomes. Human lung fetal fibroblasts contracted the collagen matrix less than the adults. Smooth muscle actin expression did not differ. TGF-beta stimulation resulted in greater Smad3 phosphorylation in fetal compared with adults. mRNA and proteomic profiling reveal a number of TGF-beta pathways, ECM components, and cytoskeletal regulatory molecules are differentially expressed between the cell types. Of note is TGF-beta receptor interacting protein 1 (TRIP-1), which we show inhibits fibroblast collagen contraction and is higher in fetal than adult fibroblasts. We conclude that human lung fetal fibroblasts are less able to contract collagen than adult lung fibroblasts. The diminished ability is not due to impediment of Smad3 activation but rather, at least in part, due to their higher level of TRIP-1 expression. TRIP-1 is a novel modulator of fibroblast collagen contraction.

The lymphatic vasculature functions to maintain tissue perfusion homeostasis. Defects in its formation or disruption of the vessels result in lymphedema, the effective treatment of which is hampered by limited understanding of factors regulating lymph vessel formation. Mice lacking T1α/podoplanin, a lymphatic endothelial cell transmembrane protein, have malformed lymphatic vasculature with lymphedema at birth, but the molecular mechanism for this phenotype is unknown. Here, we show, using primary human lung microvascular lymphatic endothelial cells (HMVEC-LLy), that small interfering RNA-mediated silence of podoplanin gene expression has the dramatic effect of blocking capillary tube formation in Matrigel. In addition, localization of phosphorylated ezrin/radixin/moesin proteins to plasma membrane extensions, an early event in the capillary morphogenic program in lymphatic endothelial cells, is impaired. We find that cells with decreased podoplanin expression fail to properly activate the small GTPase RhoA early (by 30 min) after plating on Matrigel, and Rac1 shows a delay in its activation. Further indication that podoplanin action is linked to RhoA activation is that use of a cell-permeable inhibitor of Rho inhibited lymphatic endothelial capillary tube formation in the same manner as did podoplanin gene silencing, which was not mimicked by treatment with a Rac1 inhibitor. These data clearly demonstrate that early activation of RhoA in the lymphangiogenic process, which is required for the successful establishment of the capillary network, is dependent on podoplanin expression. To our knowledge, this is the first time that a mechanism has been suggested to explain the role of podoplanin in lymphangiogenesis.

Hyperoxia is one of the major contributors to the development of bronchopulmonary dysplasia (BPD), a chronic lung disease in premature infants. Emerging evidence suggests that the arrested lung development of BPD is associated with pulmonary endothelial cell death and vascular dysfunction resulting from hyperoxia-induced lung injury. A better understanding of the mechanism of hyperoxia-induced endothelial cell death will provide critical information for the pathogenesis and therapeutic development of BPD. Epidermal growth factor-like domain 7 (EGFL7) is a protein secreted from endothelial cells. It plays an important role in vascular tubulogenesis. In the present study, we found that Egfl7 gene expression was significantly decreased in the neonatal rat lungs after hyperoxic exposure. The Egfl7 expression was returned to near normal level 2 wk after discounting oxygen exposure during recovery period. In cultured human endothelial cells, hyperoxia also significantly reduced Egfl7 expression. These observations suggest that diminished levels of Egfl7 expression might be associated with hyperoxia-induced endothelial cell death and lung injury. When we overexpressed human Egfl7 ( hEgfl7) in EA.hy926 human endothelial cell line, we found that hEgfl7 overexpression could partially block cytochrome c release from mitochondria and decrease caspase-3 activation. Further Western blotting analyses showed that hEgfl7 overexpression could reduce expression of a proapoptotic protein, Bax, and increase expression of an antiapoptotic protein, Bcl-xL. Theses findings indicate that hEGFL7 may protect endothelial cell from hyperoxia-induced apoptosis by inhibition of mitochondria-dependent apoptosis pathway.

Because echocardiographic studies on infants with chronic lung disease (CLD) suggest that pulmonary hypertension (PH) may contribute to its severity, we studied acinar arterial walls in the following surfactant-era infants: controls (n=38): 22-41 weeks of gestational age (GA), exposed briefly to oxygen and positive pressure ventilation, died within 48 hr of birth; prolonged rupture of fetal membranes (PROM) and persistent pulmonary hypertension (PPHN) (n=17); and SCORE (integrated area under curve of average daily FiO2 x average daily MAP) groups (

Inflammation is strongly linked to the pathogenesis of chronic lung disease of prematurity (CLD). Premature gas-breathing of ambient or supplemental oxygen in a host with relatively deficient and poorly inducible antioxidant defenses may itself be injurious, and further amplified by mechanical stretch injury in the surfactant-insufficient lung.1 Cellular injury provokes an inflammatory response.Since inflammation is often detected at birth in the lungs of newborns who later develop CLD,2 it has been an attractive strategy to abrogate inflammation, but the arsenal is limited. Glucocorticoids have been widely used but are acknowledged to be potentially harmful to neurologic and somatic development, and are not recommended outside controlled trials.3 The number that benefit is comparable to the number harmed, according to meta-analysis.4 More specific blockade of harmful inflammation could overcome this obstacle. Examination of the inflammatory pathways that initiate and propagate lung injury and subsequent abnormal development points to promising new strategies that may one day be tailored to individual patients.

Objective. Infants with chronic lung disease (CLD) have an arrest of primary and secondary septation. We hypothesized that this may be related to damage or abnormal development of lung collagen secondary to positive pressure ventilation. Our aims were to identify the sites and quantity of collagen in control infants 22 to 72 weeks’ postconceptional age and compare these with infants with various degrees of severity of CLD. Methods. The controls were 22 to 42 weeks’ gestation (n = 30), received minimal ventilator care, and died within 48 hours of birth, plus 5 term infants who died at 43 to 72 weeks’ postconceptional age from nonpulmonary causes. Infants who were 23 to 30 weeks’ gestation, were at risk for CLD, and lived 5 to 94 days (n = 33) were separated into 3 groups on the basis of respiratory score (score group; the integrated area under the curve of the average daily fraction of inspired oxygen × mean airway pressure [cm H2O] over the number of days lived). The score groups, Results. In the controls, the volume density of collagen decreased from a maximum of 9% at 22 weeks to 5% at term and 72 weeks. With Scores ≤69, the fraction of collagen was similar to controls, but in infants with scores 70 to 500, it was increased relative to controls. However, when collagen was expressed as the volume density of interstitial tissue, ie, excluding parenchymal air space, it increased from a low of 5% at 22 weeks to 25% at 72 weeks. In infants with scores 70 to 500, 79% of infants had collagens greater than controls. Saccular and alveolar diameter increased from 40 μm at 23 weeks to 100 μm at 72 weeks. Most infants with severe CLD (scores ≥70) had diameters more than twice that of controls at the same age. The total lung parenchymal collagen had a similar pattern as the volume density of collagen in interstitial tissue, increasing from 0.4 cm3 at 23 weeks to 9.7 cm3 at 72 weeks in the controls. Eighty-five percent of infants with scores 70 to 500 had total parenchymal collagen greater than the 95% confidence interval of the controls. With en face sections, a fine collagen mesh was seen at 23 weeks, which progressively increased in fiber size and quantity until 72 weeks. With severe CLD, the secondary collagen fibers in the saccular wall were thickened, tortuous, and disorganized relative to same-aged controls. Under 30 weeks, in the controls, the interstitium contained a wide, delicate network of interconnected collagen fibers. After positive pressure ventilation, some saccules markedly increased their diameter, which compressed and obliterated the interstitial network. In contrast with severe CLD, the interstitium was wide, with coarse wavy collagen fibers. Conclusions. Parenchymal collagen increases throughout development. Before 30 weeks, there is a delicate complex interstitial collagen network, which may be important for primary septation and subsequent normal development. Positive pressure ventilation, if excessive, and depending on lung maturity and disease state, over a short time can severely compress the interstitium and damage this collagen network and prevent normal primary septation and arrest or distort future lung development. With severe CLD, distal air space diameter increases. There is a failure of primary and secondary septation, arrested lung development and remodeling, with thickened collagenous saccular walls, and a wide interstitium with increased quantity and size of collagen fibers that can affect the mechanics of ventilation. We conclude that normal lung development is dependent on a normal interstitium and, perhaps, collagen architecture and that origins of CLD begin early in the course of positive pressure ventilation.

The peptide endothelin-1 (ET-1) plays an unknown role in the pathogenesis and progression of two important neonatal pulmonary disorders, chronic lung disease (CLD) of prematurity and persistent pulmonary hypertension of the newborn (PPHN). Inhaled nitric oxide (INO) is a proven vasodilator therapy in PPHN and is an experimental therapy in CLD. We sought to determine the effects, if any, of the interaction of inhaled INO with ET-1 in these two separate disorders. Infants (n = 21) with PPHN (mean gestation age, 39.4 weeks; mean birth weight, 3470g) were treated with INO. All infants were

Lynn D O'Hanlon, Sherry M Mabry, Ikechukwu I EkekezieChildren's Mercy Hospitals/University of Missouri-Kansas City School of Medicine, Department of Pediatrics, Section of Neonatal-Perinatal Medicine, Kansas City, MO, USAObjectives: To evaluate neurotrophin (NT) (nerve growth factor [NGF], NT-3, and brain-derived neurotrophic factor [BDNF]) expression in autopsy lung tissues of human congenital diaphragmatic hernia (CDH) infants versus that of infants that expired with: 1) "normal" lungs (controls); 2) chronic lung disease (CLD); and 3) pulmonary hypertension (PPHN).Hypothesis: NT expression will be significantly altered in CDH lung tissue compared with normal lung tissue and other neonatal lung diseases.Study design: Immunohistochemical studies for NT proteins NGF, BDNF, and NT-3 were applied to human autopsy neonatal lung tissue samples.Subject selection: The samples included a control group of 18 samples ranging from 23-week gestational age to term, a CDH group of 15 samples, a PPHN group of six samples, and a CLD group of 12 samples.Methodology: The tissue samples were studied, and four representative slide fields of alveoli/saccules and four of bronchioles were recorded from each sample. These slide fields were then graded (from 0 to 3) by three blinded observers for intensity of staining.Results: BDNF, NGF, and NT-3 immunostaining intensity scores were significantly decreased in the CDH lung tissue (n=15) compared with normal neonatal lung tissue (n=18) (P

Monocyte chemoattractant protein-1 (MCP-1), acting through its C-C chemokine receptor 2 (CCR-2), has important roles in inflammation, angiogenesis, and wound repair. The individual and combined effects of inhaled nitric oxide (NO) and hyperoxia on lung MCP-1 and CCR-2 in relation to lung leukocyte dynamics are unknown. Because MCP-1 gene is up-regulated by oxidants, we hypothesized that inhaled NO with hyperoxia will increase MCP-1 production and CCR-2 expression more than either gas alone. We randomly assigned young piglets to breathe room air (RA), RA+50 ppm NO (RA+NO), O(2), or O(2)+NO for 1 or 5 d before sacrifice. Lungs were lavaged and tissues preserved for hybridization studies, Western blotting, histology, and immunohistochemistry. The results show that lung MCP-1 production and alveolar macrophage count were significantly elevated in the 5-d O(2) and O(2)+NO groups relative to the RA group (p < or = 0.05). In contrast, lung CCR-2 abundance was diminished in the O(2) group (p

Background. Infants Methods. The controls were 22 to 42 weeks' gestation (n = 71), received ventilator care, and died within 48 hours of birth, plus 7 term infants who died at 43 to 50 weeks' postconceptional age from nonpulmonary causes. Infants who were 23 to 30 weeks' gestation, at risk for CLD, and who lived 5 to 59 days (n = 44), were separated into groups based on respiratory score (SCORE; The integrated area under the curve of the average daily fraction of inspired oxygen × mean airway pressure (cm H2O) over the number of days lived). The SCORE groups, Results. In the controls, the volume density of parenchymal elastic tissue and absolute quantity of elastic tissue increased progressively from 22 to 50 weeks. In infants with CLD and SCORE ≥20, the volume density and absolute quantity of elastic tissue increased significantly. Mean absolute elastic tissue in the 20 to 69 group was 0.76 ± 0.20 cm3 greater than in the Discussion. Lung elastic tissue maturation is tightly controlled during fetal development. With increasing SCORE, elastic tissue increased >200%, accounting, in part, for the positive end-expiratory pressure needed to maintain end-expiratory lung volume in infants at risk for CLD. Saccule and duct diameters more than doubled, and septa thickened significantly in CLD. We propose the following sequence to be operative in CLD: at birth, the preterm infant (≤30 weeks) has inadequate elastic tissue and elastic recoil, but high surface tension recoil. After surfactant treatment, surface tension recoil markedly decreases, permitting the saccules and ducts, with very low elastic recoil, to be overstretched by volutrauma. The damaged lung responds with elastosis, distorted acinar growth, cellular influx, and upregulation of inflammatory and reparative proteins. This hypothesis can be summarized by the following terms: lung immaturity, inflammation, volutrauma, and elastic tissue alterations.

Top of pageAbstract Background: Neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3)] are growth factors that function as mediators for the development, survival and differentiation of neurons and other types of cells. During normal tissue morphogenesis, neurogenesis and myogenesis proceed as tightly linked processes. In the condition, congenital diaphragmatic hernia (CDH), there is failure of the diaphragm muscle to develop with consequent pulmonary hypoplasia and pulmonary hypertension. The probability that impaired neurogenesis, or coordination of neuro and myogenesis, underlies the disrupted development of the diaphragm muscle in CDH, needs to be explored. Objectives: To determine the expression of neurotrophic factors (NGF, NT-3 and BDNF) in neonatal lung disease; specifically congenital diaphragmatic hernia (CDH), persistent pulmonary hypertension (PPHN) and chronic lung disease (CLD) vs. normal lung tissue. Methods: Immunohistochemical studies for neurotrophin proteins (specific antibody staining using polyclonal rabbit anti-human NGF, BDNF and NT-3) were applied to human neonatal lung tissue samples. The samples included a control group of 18 samples ranging from 23wk EGA to term, a CDH group of 15 samples, a PPHN group of 6 samples and a CLD group of 12 samples. The tissue samples were studied and 4 representative slide fields of aveoli/saccules and 4 of bronchioles were recorded from each sample. These slide fields were then graded (from 0-3) by several blinded observers for intensity of staining. Results: BDNF, NGF and NT-3 immunostaining intensity scores were significantly less in the CDH lung tissue samples (n 15) compared to normal neonatal lung tissue (n 18) (p

Neurotrophins and their receptors have important roles in survival of neural tissues that may extend to cells of non neural origin. Their presence and response to hyperoxia-induced lung injury has not been fully characterized. We randomized four day old rat pups to breath either room air or hyperoxia (FIO2 ≥95%) for 1, 3, 6 and 10 days. By Western blot we found a significant decline in the hyperoxic-exposed group of Neurotrophin-3 (NT-3) and its high affinity receptor TRK-C, beginning at day 3 with maximal decline at day 6. NT-3 and TRK-C are widely distributed in the lungs both in the airways and air sacs as seen by immunohistochemistry. We repeated the experiment using human fetal lung fibroblast under culture conditions exposed to 95% oxygen and found the same results. NT-3 and its high affinity TRK-C receptor level declined significantly by 4 hours and were undetectable by 12 hours of exposure as determined by Western blot. We conclude that hyperoxia decreased lung expression of NT-3 and its receptor. The findings may have implications for lung growth and development.

Inhaled nitric oxide (NO) is now established as a selective pulmonary vasodilator. Toxicity potential of NO however remains a great concern. The postulated injurious mechanisms include NO-induced activation of matrix metalloproteinases (MMP) with consequent breakdown of the alveolar extracellular matrix. Endothelin-1 (ET-1) is reportedly a marker of acute pulmonary injury. 8-Isoprostanes are lipid peroxidation products of oxyradical-induced cell membrane injury. We hypothesized that lung lavage fluid from animals exposed to hyperoxia and NO will show increased laminin and hydroxyproline contents as early markers of alveolar capillary basement membrane and matrix breakdown. Additionally, we reasoned that lung lavage fluid ET-1 and 8-isoprostane concentration will correlate with laminin and hydroxyproline concentration. To test this hypothesis, we designed the following study. Twenty-eight newborn piglets were randomized into four exposure groups to breathe for five days in a 200-liter exposure chamber. The groups were (i) room air (RA), (ii) RA+50 ppm NO, (RA+NO), (iii) hyperoxia(FiO2≥0.96) (O2), and (iv) hyperoxia + 50 ppm NO(O2+NO). Lung lavage fluid was obtained and analyzed by ELISA to quantitate laminin, ET-1, and 8-isoprostane concentrations. Lavage fluid hydroxyproline was measured by a colorimetric method. Mean hydroxyproline levels were about twenty fold higher in the O2 and O2 + NO group as compared to other groups. ET-1 concentration was higher in the O2 + NO group than in any other group (P

Nitric oxide (NO) down regulates the neutrophil CD18 receptor and is purported to decrease lung inflammation. However, in clinical situations, NO is used in the presence of oxygen (O2), a lung inflammatory gas.

Acinar Muscle Development From 22-42 Weeks Gestation and With Bronchopulmonary Dysplasia (BPD) 1758

Background Myofibroblasts are the critical effector cells in the pathogenesis of pulmonary fibrosis which carries a high degree of morbidity and mortality. We have previously identified Type II TGFβ receptor interacting protein 1 (TRIP-1), through proteomic analysis, as a key regulator of collagen contraction in primary human lung fibroblasts—a functional characteristic of myofibroblasts, and the last, but critical step in the process of fibrosis. However, whether or not TRIP-1 modulates fibroblast trans-differentiation to myofibroblasts is not known. Methods TRIP-1 expression was altered in primary human lung fibroblasts by siRNA and plasmid transfection. Transfected fibroblasts were then analyzed for myofibroblast features and function such as α-SMA expression, collagen contraction ability, and resistance to apoptosis. Results The down-regulation of TRIP-1 expression in primary human lung fibroblasts induces α-SMA expression and enhances resistance to apoptosis and collagen contraction ability. In contrast, TRIP-1 over-expression inhibits α-SMA expression. Remarkably, the effects of the loss of TRIP-1 are not abrogated by blockage of TGFβ ligand activation of the Smad3 pathway or by Smad3 knockdown. Rather, a TRIP-1 mediated enhancement of AKT phosphorylation is the implicated pathway. In TRIP-1 knockdown fibroblasts, AKT inhibition prevents α-SMA induction, and transfection with a constitutively active AKT construct drives collagen contraction and decreases apoptosis. Conclusions TRIP-1 regulates fibroblast acquisition of phenotype and function associated with myofibroblasts. The importance of this finding is it suggests TRIP-1 expression could be a potential target in therapeutic strategy aimed against pathological fibrosis.