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Background Acute respiratory distress syndrome (ARDS) is a life-threating condition with high morbidity and mortality. Inflammation is the main factor in the pathogenesis of ARDS. Therefore systemic corticosteroids are a rational therapeutic approach, but the effect of corticosteroids is still unclear. In this study, we looked at the effects of corticosteroids in ventilated sheep with ARDS, induced by lung lavage. Methods We performed a prospective, randomised study in 64 ventilated sheep with ARDS, to evaluate the effect of corticosteroids and oxygen concentration on gas exchange and lung injury. Oxygenation index (OI) and ventilation efficacy index (VEI) were calculated to evaluate gas exchange. Lung injury was assessed by inflammatory response in broncho-alveolar lavage fluid (BALF) and plasma and histology of the lung. Results OI, VEI, lung inflammation, surfactant production, or lung histology was not influenced by corticosteroids. In the 100% oxygen groups, OI was higher and total number of cells and disaturated phospholipids were lower in BALF. Conclusion Our study showed that corticosteroids did not influence inflammation in early phase ARDS and that hyperoxia aggravated lung injury which could not be modulated by dexamethasone in early phase ARDS. Keywords Acute respiratory distress syndrome * Dexamethasone * Oxygen * Lung injury, Introduction Acute respiratory distress syndrome (ARDS) is a life-threating condition with high morbidity and mortality [1]. It is characterized by hypoxemia and bilateral infiltrations on X-ray, in the absence of [...]

Background Recruitment manoeuvres are widely used in clinical practice to open the lung and prevent lung injury by derecruitment, although the evidence is still discussed. In this study two different recruitment manoeuvres were compared to no recruitment manoeuvres (control) in ventilated sheep with acute respiratory distress syndrome (ARDS), induced by lung lavage. Methods We performed a prospective, randomised study in 26 ventilated sheep with ARDS, to evaluate the effect of two different recruitment manoeuvres on gas exchange, blood pressure and lung injury. The two different recruitment manoeuvres, the high pressure recruitment manoeuvre (HPRM), with high peak pressure, and the smooth and moderate recruitment manoeuvre (SMRM), with lower peak pressure, were compared to controls (no recruitment) after disconnection. Oxygenation index and ventilation efficacy index were calculated to evaluate gas exchange. Lung injury was assessed by inflammatory response in broncho-alveolar lavage fluid (BALF) and blood and histology of the lung. Results Oxygenation index improved significantly after both recruitment manoeuvres compared with controls, but no significant difference was found between the recruitment manoeuvres. Blood pressure decreased after HPRM but not after SMRM. HPRM induced a higher number of total cells and more neutrophils in the BALF. In the histology of the lung, mean alveolar size was increased in the dorsocranial region of the lung of SMRM compared to controls. Conclusion Recruitment manoeuvres improved oxygenation, but SMRM was superior, with respect to hemodynamics and pulmonary inflammation, in ventilated sheep suffering from ARDS induced by lung lavage. Keywords ARDS * Recruitment manoeuvres * Lung injury * Mechanical ventilation * Blood pressure, Background Mechanical ventilation is a life-saving therapy in patients with acute respiratory distress syndrome (ARDS). Mechanical ventilation can also cause additional lung injury [1-3], so a 'lung protective strategy' has [...]

Background Recruitment manoeuvres are widely used in clinical practice to open the lung and prevent lung injury by derecruitment, although the evidence is still discussed. In this study two different recruitment manoeuvres were compared to no recruitment manoeuvres (control) in ventilated sheep with acute respiratory distress syndrome (ARDS), induced by lung lavage. Methods We performed a prospective, randomised study in 26 ventilated sheep with ARDS, to evaluate the effect of two different recruitment manoeuvres on gas exchange, blood pressure and lung injury. The two different recruitment manoeuvres, the high pressure recruitment manoeuvre (HPRM), with high peak pressure, and the smooth and moderate recruitment manoeuvre (SMRM), with lower peak pressure, were compared to controls (no recruitment) after disconnection. Oxygenation index and ventilation efficacy index were calculated to evaluate gas exchange. Lung injury was assessed by inflammatory response in broncho-alveolar lavage fluid (BALF) and blood and histology of the lung. Results Oxygenation index improved significantly after both recruitment manoeuvres compared with controls, but no significant difference was found between the recruitment manoeuvres. Blood pressure decreased after HPRM but not after SMRM. HPRM induced a higher number of total cells and more neutrophils in the BALF. In the histology of the lung, mean alveolar size was increased in the dorsocranial region of the lung of SMRM compared to controls. Conclusion Recruitment manoeuvres improved oxygenation, but SMRM was superior, with respect to hemodynamics and pulmonary inflammation, in ventilated sheep suffering from ARDS induced by lung lavage. Keywords ARDS * Recruitment manoeuvres * Lung injury * Mechanical ventilation * Blood pressure, Background Mechanical ventilation is a life-saving therapy in patients with acute respiratory distress syndrome (ARDS). Mechanical ventilation can also cause additional lung injury [1-3], so a 'lung protective strategy' has [...]

Purpose Restoring the barrier integrity of the alveolar epithelium after injury is pivotal. In the current study, we evaluated the effects of surfactant, surfactant protein A (SP-A), transforming growth factor β (TGF-β), and analogues of SP-A on alveolar epithelial repair. Additionally, we assessed the influence of microvascular endothelial cells on reepithelialization. Methods Repair was studied in an in vitro model system consisting of a bilayer coculture of A549 and human pulmonary microvascular endothelial cells (HPMECs), which stably expressing fluorescent proteins. The epithelial repair was assessed in a scratch assay using vital fluorescence microscopy and compared with a monolayer of A549 cells. Results HMPEC cells differentially modulated the response of the A549 cells. Surfactant and SP-A augmented the reepithelialization in the presence of HPMECs, whereas in the absence of HPMECs, surfactant inhibited wound healing and SP-A failed to alter the response. Like SP-A, a structural analogue of its collagenous tail domain augmented the reepithelialization in the model system, whereas an analogue of its head domain did not alter the response. Additionally, we demonstrated that TGF-β associated with SP-A was able to initiate the Smad-dependent TGF-β pathway and that both TGF-β and TGF-β free SP-A were able to stimulate wound healing in the bilayer model. Conclusions These data show that surfactant, SP-A and TGF-β, influence epithelial repair in vitro and that the microvascular endothelial cells can modulate the response. This indicates that surfactant and SP-A could play a role in alveolar epithelial repair and that the microvascular endothelium may be involved in these processes. Keywords Acute lung injury * Acute respiratory distress syndrome * Pulmonary surfactant * Collectin * Wound healing, Introduction Disruption of the alveolocapillary barrier is at the basis of several life-threatening pulmonary disorders, such as acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) [1]. Restoring the [...]

Bronchopulmonary dysplasia is associated with chorioamnionitis and fetal lung inflammation. Ureaplasma species are the bacteria most frequently isolated from chorioamnionitis. Very chronic ureaplasma colonization of amniotic fluid causes low-grade lung inflammation and functional lung maturation in fetal sheep. Less is known about shorter exposures of the fetal lung. Therefore, we hypothesized that ureaplasmas would cause an acute inflammatory response that would alter lung development. Singleton ovine fetuses received intra-amniotic Ureaplasma parvum serovar 3 or control media at 110, 117, or 121 days and were delivered at 124 days gestational age (term = 150 days). Inflammation was assessed by 1) cell counts in bronchoalveolar lavage fluid (BALF), and 2) cytokine mRNA measurements, immunohistochemistry, and flow cytometry for inflammatory cells and elastin and [alpha]-smooth muscle actin ([alpha]-SMA) staining in lung tissue. Neutrophils were increased in BALF 3 days after exposure to ureaplasmas (P = 0.01). Myeloperoxidase-positive cells increased after 3 days (P = 0.03), and major histocompatibility complex (MHC) class II-positive cells increased after 14 days of ureaplasma exposure (P = 0.001). PU.1 (macrophage marker)- or CD3 (T lymphocyte marker)-positive cells were not induced by ureaplasmas. CD3-positive cells in the posterior mediastinal lymph node increased in ureaplasma-exposed animals at 3, 7, and 14 days (P = 0.002). Focal elastin depositions decreased in alveolar septa at 14 days (P = 0.002), whereas [alpha]-SMA increased in arteries and bronchioli. U. parvum induced a mild acute inflammatory response and changed elastin and [alpha]-SMA deposition in the lung, which may affect lung structure and subsequent development. innate immunity; maturation; lung development; bronchopulmonary dysplasia; Ureaplasma species doi: 10.1152/ajplung.00183.2010.

The respiratory distress syndrome (RDS) contributes to perinatal morbidity and mortality associated with preterm birth. Surfactant protein B (SP-B) is decreased in RDS. Both maternal antenatal steroid administration and chorioamnionitis reduce the incidence and severity of RDS. An important mediator in chorioamnionitis is IL-6 using the JAK-STAT signaling pathway for signal transduction. We hypothesized that the steroids, betamethasone (BTM) and dexamethasone (DXM), and IL-6 had synergistic effects on SP-B gene expression and STAT3 phosphorylation in H441 cells. DXM and BTM increased SP-B mRNA levels by 16.5 (13.3)-fold and IL-6 alone by 2.3-fold. After 48-h exposure of cells to DXM or BTM, IL-6 caused a significantly greater increase in SP-B mRNA levels (28.1-fold) than IL-6 or glucocorticolds alone. Whereas IL-6 stimulated tyrosine phosphorylation of STAT3 in a time- and dose-dependent way, DXM and BTM had no effect on STAT3 phosphorylation. Both DXM and BTM could potentiate IL-6-induced phosphorylation of STAT3. The synergism of glucocorticoids and IL-6 on SP-B gene expression and the effect of glucocorticoids on IL-6-induced STAT3 phosphorylation could be blocked by a JAK inhibitor. Expression level analysis showed that glucocorticoids increased the expression of the IL-6-binding s-subunit receptor (IL-6R) on mRNA and protein level. Our findings could represent an example of a pulmonary regulation system in which one role of glucocorticoids is to increase the effect of a cytokine by upregulation of its receptor. The described in vitro interaction of IL-6 and glucocorticoids could help explain the clinical observation that prenatal inflammation in preterm babies with antenatal steroid administration can attenuate severity of RDS. dexamethasone; betamethasone; surfactant protein B; interleukin-6 receptor; STAT3; Janus kinase; respiratory distress syndrome doi: 10.1152/ajplung.00055.2010.

Byline: J. Jane Pillow (1,5), Noah H. Hillman (2), Graeme R. Polglase (1), Timothy J. M. Moss (3), Suhas G. Kallapur (2), Fook-Choe Cheah (2), Boris W. Kramer (4), Alan H. Jobe (2) Keywords: Humidity; Temperature; Hyperoxia; Respiratory distress syndrome; Infant; Preterm Abstract: Purpose The relative contributions of factors influencing lung injury immediately after birth are poorly understood. We hypothesized that oxygen content and humidity of inspired air would influence markers of pulmonary inflammation in ventilated lambs. Methods Lambs delivered at 140 days gestation (term = 150 days) were assigned to one of five groups (n = 5--6/group): unventilated controls, or ventilation with 21 or 100% O.sub.2 that was either heated and humidified or cold and dry. Lambs were ventilated gently for 3 h: blood gases were recorded regularly. Bronchoalveolar lavage and samples of tracheal mucosa and lung were collected post mortem. Results Arterial pH was lower [mean difference (95% CI): -0.07 (-0.13, -0.03)], while there was an increase in PaCO.sub.2 [mean difference (95% CI): 10.2 (2.4, 17.9)] and fold change in lung pro-inflammatory IL-1[beta] cytokine mRNA [mean difference (95% CI): 28.3 (0.3, 56.2)] or IL-8 [mean difference (95% CI): 27.8 (7.9, 47.7)] cytokine mRNA expression with 100% O.sub.2 relative to 21% O.sub.2. Cold dry inspired gas did not influence gas exchange or dynamic mechanics at 3 h compared to heated humidified gas. Compared to 100% inspired O.sub.2, cold dry inspired gas had less marked effect on fold change in lung pro-inflammatory IL-1[beta] cytokine mRNA [mean difference (95% CI): 27.2 (-0/8, 55.1)] or IL-8 [mean difference (95% CI): 14.5 (5.5, 34.4)] cytokine mRNA expression, although cilial dysfunction/damage was evident on electron microscopy, especially when exposure to cold dry gas was combined with hyperoxia. Conclusions In near-term neonatal lambs ventilated for 3 h, hyperoxia was associated a more powerful stimulus for pulmonary dysfunction and upregulation of inflammatory cytokines than cold dry gas. Author Affiliation: (1) School of Women's and Infants' Health, The University of Western Australia, c/- 374 Bagot Rd, Subiaco, Perth, 6008, Australia (2) Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati School of Medicine, 3333 Burnet Ave, Cincinnati, OH, 45229, USA (3) Department of Physiology, Monash University, Building 13F, Clayton, VIC, 3800, Australia (4) Department of Pediatrics, Maastricht University Medical Center, Postbus 5800, 6202 AZ, Maastricht, The Netherlands (5) Neonatal Clinical Care Unit, King Edward Memorial Hospital, 374 Bagot Rd, Subiaco, Perth, 6008, Australia Article History: Registration Date: 25/08/2009 Received Date: 07/10/2008 Accepted Date: 07/08/2009 Online Date: 15/09/2009 Article note: This research was presented at the annual conference of The Perinatal Society of Australia and New Zealand (April 2007) and the Pediatric Academic Societies Meeting (Toronto, 2007). Electronic supplementary material The online version of this article (doi: 10.1007/s00134-009-1624-z) contains supplementary material, which is available to authorized users.

Preterm infants exposed to chorioamnionitis and preterm sheep fetuses exposed to intra-amniotic (IA) LPS have lung inflammation, increased IL-8 levels, and lung maturation. We tested the hypothesis that IL-8 signaling mediates IA LPS-induced lung inflammation and lung maturation. Two strategies were used: I) we tested if IA injection of recombinant sheep IL-8 (rsIL-8) induced fetal inflammation and 2) if IL-8 signaling was blocked by a novel CXCR2 receptor blocker, nicotinanilide thioglycolate methyl ester (NTME). To test effects of IL-8 in the fetus, rsIL-8 was given intravascularly (50 [micro]g) at 124 [+ or -] 1 day of gestation (term = 150 days). A separate group of sheep was given IA rsIL-8 (100 [micro]g) and delivered 5 h to 7 days later at 124 [+ or -] 1 day of gestation. After confirming efficacy of the CXCR2 inhibitor, effects of IL-8 blockade were tested by injecting fetal sheep intramuscularly with NTME (10 rag) before IA injection of Escherichia coli LPS (10 mg). Sheep fetuses were delivered 1 or 7 days after injections at 124 [+ or -] 1 day of gestation. IA rsIL-8 induced a modest fivefold increase in bronchoalveolar lavage (BAL) monocytes and neutrophils and increased lung monocyte hydrogen peroxide generation. However, rsIL-8 did not induce lung maturation. Intravascular rsIL-8 did not change fetal cardiovascular variables, blood pH, or blood leukocyte counts. Inhibition of CXCR2 decreased IA LPS-induced increases in BAL proteins at 1 day but not at 7 days. NTME did not significantly decrease IA LPS-induced BAL leukocyte influx and lung cytokine mRNA expression. Inhibition of CXCR2 did not change IA LPS-induced lung maturation. IL-8 signaling does not mediate LPS-induced lung inflammation and lung maturation. prematurity; respiratory distress syndrome; bronchopulmonary dysplasia; fetal inflammatory response syndrome; CXCR2

Chorioamnionitis, a risk factor for bronchopulmonary dysplasia in preterm infants, causes an influx of inflammatory cells into the fetal lung. Using a fetal sheep model, we evaluated the time course of activation, functional maturity, and apoptosis of the leukocytes recruited to the fetal air spaces by lipopolysaccharide (LPS). Time-mated sheep were given intra-amniotic injections with 10 mg of Escherichia coli LPS or saline 2 or 7 days before preterm delivery at 124 days of gestation (term is 150 days). Both neutrophils and monocytes in bronchoalveolar lavage fluid (BALF) had activated NF-[kappa]B after 2- and 7-day LPS exposures. These neutrophils and monocytes expressed the activation factor CD 11b and the maturation factor PU.1 at 2 days, and increased PU.1 expression was detected in macrophages at 7 days. Leukocyte oxidative burst activity was greatest at 7 days. BALF lipid peroxidation increased fivefold at 2 days, while protein carbonyls increased eightfold at 7 days. Nitrative stress was not detected in the BALF, but leukocytes in the lung expressed nitric oxide synthase (NOS)II (inducible NOS). BALF leukocytes expressed the antioxidant peroxiredoxin V. Lung glutathione peroxidase was also increased with LPS exposure. There was minimal apoptosis of airway and lung leukocytes assessed by caspase-3 activation. Intra-amniotic LPS recruits leukocytes to the fetal air space that have a persistent activation. These results have implications for the pathogenesis of lung inflammatory disorders in the preterm. bronchopulmonary dysplasia; nuclear factor-[kappa]B; oxidative stress; preterm lung; PU.1

The fetal lung normally contains immature monocytes and very few mature macrophages. The chorioamnionitis frequently associated with preterm birth induces monocyte influx into the fetal lung. Previous studies demonstrated that monocytes in the developing lung can mediate lung injury responses that resemble BPD in humans. We hypothesized that chorioamnionitis would induce maturation of immature monocytes in the fetal lung. Groups of three to seven time-mated ewes received saline or 10 mg of endotoxin (Escherichia coli 055:B5) in saline by intra-amniotic injection for intervals from 1 to 14 days before operative delivery at 124 days of gestational age. Monocytic cells from lung tissue were recovered using Percoll gradients. Monocytic cells consistent with macrophages were identified morphologically and by myosin heavy chain class II expression. An increase in macrophages was preceded by induction of granulocyte-macrophage colony-stimulating factor in the lung and subsequent activation of the transcription factor PU.1. The production of IL-6 by monocytes/macrophages in response to endotoxin challenge in vitro increased 7 and 14 days after exposure to intra-amniotic endotoxin. Recombinant TNF-[alpha] induced IL-6 production by lung monocytic cells exposed to intra-amniotic endotoxin but not in control cells. Monocytic phagocytosis of apoptotic neutrophils also increased 7 and 14 days after exposure to intra-amniotic endotoxin. Intra-amniotic endotoxin induced lung monocytes to develop into functionally mature cells consistent with macrophages. These findings have implications for lung immune responses after exposure to chorioamnionitis. macrophage; fetal immunity; bronchopulmonary dysplasia; chorioamnionitis; granulocyte-macrophage colony-stimulating factor; PU.1

Chorioamnionitis is frequently associated with preterm birth and increases the risk of adverse outcomes such as bronchopulmonary dysplasia (BPD). Transforming growth factor (TGF)-[beta]1 is a key regulator of lung development, airway remodeling, lung fibrosis, and regulation of inflammation, and all these processes contribute to the development of BPD. Connective tissue growth factor (CTGF) is a downstream mediator of some of the profibrotic effects of TGF-[beta]1, vascular remodeling, and angiogenesis. TGF-[beta]1-induced CTGF expression can be blocked by TNF-[alpha]. We asked whether chorioamnionitis-associated antenatal inflammation would regulate TGF-[beta]1, the TGF-[beta]1 signaling pathway, and CTGF in preterm lamb lungs. Fetal sheep were exposed to 4 mg of intraamniotic endotoxin or saline for 5 h, 24 h, 72 h, or 7 days before preterm delivery at 125 days gestation (full term = 150 days). Intra-amniotic endotoxin increased lung TGF-[beta]1 mRNA and protein expression. Elevated TGF-[beta]1 levels were associated with TGF-[beta]1-induced phosphorylation of Smad2. CTGF was selectively expressed in lung endothelial cells in control lungs, and intra-amniotic endotoxin caused CTGF expression to decrease to 30% of control values and TNF-[alpha] protein to increase. The antenatal inflammation-induced TGF-[beta]1 expression and Smad signaling in the fetal lamb lung may contribute to impaired lung alveolarization and reduced lung inflammation. Decreased CTGF expression may inhibit vascular development or remodeling and limit lung fibrosis during remodeling. These effects may contribute to the impaired alveolar and pulmonary vascular development that is the hallmark of the new form of BPD. chorioamnionitis; bronchopulmonary dysplasia; Smad signaling; fibrosis

Surfactant protein A (SP-A) and transforming growth factor-[beta]1 (TGF-[beta]1) have been shown to modulate the functions of different immune cells and specifically to inhibit T lymphocyte proliferation. The aim of the present study was to elucidate whether the Smad signaling pathway, which is activated by TGF-[beta]1, also plays a role in SP-A-mediated inhibition of [CD4.sup.+] T lymphocyte activation. Recombinant human SP-A1 expressed in Chinese hamster ovary cells [rSP-A1m (mammalian)], but not recombinant Baculovirus-derived rSP-[A1.sup.hyp] (hydroxyproline-deficient), suppressed T lymphocyte proliferation and IL-2 mRNA expression. To test whether SP-A induced Smad signaling, a Smad3/4-specific reporter gene was transfected in primary human [CD4.sp.+] T lymphocytes. Only rSP-A1m, but not [rSP-A1.sup.hyp], induced Smad-specific reporter genes, Smad2 phosphorylation, and Smad7 mRNA expression. The effect of rSP-A1m was mediated through the TGF-[beta]RII and could he antagonized by anti-TGF-[beta]1 neutralizing antibodies and sTGF-[beta]RII. Western blot and ELISA analysis revealed that rSP-A1m, but not rSP-[A1.sup.hyp], contained TGF-[beta]1. TGF-[beta]1 was responsible for the differences in inhibition of [CD.sup.4+] T lymphocyte proliferation and activation of the Smad signaling pathway between rSP-A1m and [rSP-A1.sup.hyp]. After acidification, native SP-A, obtained from patients with alveolar proteinosis, also induced Smad signaling in human [CD.sup.4+] T lymphocytes leading to an increased inhibition of T lymphocyte proliferation, thus indicating the presence of inactive, latent TGF-[beta]1 in native SP-A samples. Association between SP-A and latent TGF-[beta]1 provides a possible novel mechanism to regulate TGF-[beta]1-mediated inflammation and fibrosis reactions in the lung but also leads to possible misinterpretation of immune-modulator functions of SP-A. Monitoring of SP-A preparations for possible TGF-[beta]1 is essential. Smad signaling; acidification; surfactant protein A; transforming growth factor-[beta]1

Chronic early gestational chorioamnionitis is associated with development of bronchopulmonary dysplasia in preterm infants. A single intra-anmiotic exposure to endotoxin decreased alveolarization and reduced expression of endothelial proteins in 125-day gestational age preterm lambs. We hypothesized that prolonged exposure to intra-amniotic endotoxin would cause progressive lung inflammation and inhibit alveolar and pulmonary vascular development. Endotoxin (1 mg/day) or saline was administered via an intra-amniotic osmotic pump from 80 to 108 days of gestational age (continuous pump) or by four weekly 10-mg intraanmiotic endotoxin rejections starting at 100 days of gestational age (multiple dose). Lung morphometry, lung inflammation, vascular effects, and lung maturation were measured at delivery. The continuous pump lambs delivered at 100 days (~70% of total endotoxin exposure) had lung inflammation, fewer saccules, and decreased endothelial proteins endothelial nitric oxide synthase and VEGF receptor 2 expression compared with controls. The continuous pump (delivered at 138 days) and multiple dose lambs (delivered at 130 and 145 days) had mild persistent lung inflammation and no significant differences in lung morphometry or expression of endothelial proteins compared with controls. Surfactant saturated phosphatidylcholine pool sizes were increased in all endotoxin-exposed groups, but lung function was not changed relative to controls. Contrary to our hypothesis, a prolonged fetal exposure to intra-amniotic endotoxin caused mild persistent inflammation but did not lead to progressive structural abnormalities in lungs of near-term gestation lambs. chorioamnionitis; bronchopulmonary dysplasia; respiratory distress syndrome lung maturation- surfactant

TNF-[alpha] has been associated with chorioamnionitis and the subsequent development of bronchopulmonary dysplasia in preterm infants. We asked whether bioactive recombinant ovine TNF-[alpha] could induce chorioamnionitis, lung inflammation, lung maturation, and systemic effects in fetal sheep. We compared the responses to IL-1[alpha] a cytokine known to induce these responses in preterm sheep. Intra-amniotic TNF-[alpha] caused no chorioamnionitis, no lung maturation, and a very small increase in inflammatory cells in the fetal lung after 5 h, 2 days (d), and 7 d. In contrast, IL-1[alpha] induced inflammation and lung maturation. TNF-[alpha] given into the airways at birth increased granulocytes in the bronchoalveolar lavage fluid of ventilated preterm lungs and decreased the mRNA for surfactant protein C but did not adversely effect postnatal lung function. An intravascular injection of IL-1[alpha] caused a systemic inflammatory response in fetal sheep, whereas there was no fetal response to intravascular TNF-[alpha]. Fetal and newborn preterm sheep are minimally responsive to TNF-[alpha]. Therefore, the presence of a mediator such as TNF-[alpha], in a developing animal does not necessarily mean that it is causing the responses anticipated from previous results in adult animals. inflammation; fetal maturation; cytokines; interleukin-1[alpha]; chorioamnionitis; endotoxin

Antenatal betamethasone (Beta) is widely used in women with asymptomatic chorioamnionitis at risk for preterm delivery, but its effects on fetal inflammation are unstudied. Groups of ewes at 109 [+ or -] 1 days of gestation received the following treatments: intra-amniotic (IA) saline (control), 0.5 mg/kg intramuscular Beta, 10 mg IA endotoxin (Endo), and Beta + 2 h later Endo (Beta + Endo). Beta suppressed Endo-induced lung inflammation at 1 day. However, compared with Endo 5 days after treatment, Beta + Endo lambs had increased alveolar neutrophils, proinflammatory cytokine mRNA expression, and serum amyloid A3 (SAA3) mRNA expression. IL-1[beta] mRNA expression was localized to the inflammatory cells, whereas SAA3 mRNA expression was induced in the bronchial epithelium and the inflammatory cells. Compared with Endo, Beta + Endo lambs had increased lung inflammation but equivalent lung volumes 15 days after treatment. The late increase in inflammation in the Beta + Endo animals suggests that glucocorticoids impair the ability of the preterm lung to downregulate Endo-induced inflammation after fetal clearance of the glucocorticoids. These results have implications for lung inflammation and bronchopulmonary dysplasia in preterm infants exposed to chorioamnionitis and maternal glucocorticoids. bronchopulmonary dysplasia; acute-phase reactant; proinflammatory cytokines; endotoxin tolerance; chorioamnionitis

Chorioamnionitis is frequent in preterm labor and increases the risk of bronchopulmonary dysplasia. We hypothesized that intra-amniotic endotoxin injures the lung in utero, causing a sequence of inflammation and tissue injury similar to that which occurs in the injured adult lung. Preterm lamb lungs at 125 days gestational age were evaluated for indicators of inflammation, injury, and repair 5 h, 24 h, 72 h, and 7 days after 4 mg of intra-amniotic endotoxin injection. At 5 h, the epithelial cells in large airways expressed heat shock protein 70, and alveolar interleukin-8 was increased. Surfactant protein B (SP-B) decreased in alveolar type II cells at 5 h, and SP-B in lung tissue and alveolar lavage fluid increased by 72 h. By 24 h, neutrophils were recruited into the large airways, and cell death was the highest. Alveolar type II cells decreased by 25% at 24 h, and proliferation was highest at 72 h, consistent with tissue remodeling. Intraamniotic endotoxin caused surfactant secretion, inflammation, cell death, and remodeling as indications of lung injury. The recovery phase was accompanied by maturational changes in the fetal lung. surfactant; lung maturation; alveolar type II cells; respiratory distress syndrome; chorioamnionitis

Antenatal inflammation may be an important triggering event in the pathogenesis of bronchopulmonary dysplasia but may also accelerate fetal lung maturation. We examined the effects of intra-amniotic (IA) interleukin (IL)-1[alpha] and IL-1[beta] on maturation of the fetal sheep lung. These cytokine effects were compared with IA endotoxin, a potent proinflammatory stimulus that accelerated lung maturation. Date-bred ewes received 15 or 150 [micro]g recombinant ovine IL-1[alpha] or IL-1[beta] or 10 mg Escherichia coli endotoxin by IA injection at 118 days gestation (term = 150 days), and fetuses were delivered at 125 days. IL-1[alpha] and IL-1[beta] improved lung function and increased alveolar saturated phosphatidylcholine (Sat PC) and surfactant protein mRNA expression at the higher dose. The maturation response to IL-1[alpha] was greater than that to IL-1[beta], which was similar to endotoxin response. Inflammation was also more pronounced after IL-1[alpha] treatment. Only endotoxin animals had residual inflammation of the fetal membranes at 7 days. Lung compliance, lung volume, and alveolar Sat PC were positively correlated with residual alveolar wash leukocyte numbers 7 days after IL-1 treatment, suggesting a link between lung inflammation and maturation. respiratory distress syndrome; bronchopulmonary dysplasia; chorioamnionitis; surfactant; cytokines

Background: Accumulating evidence implicates early life factors in the aetiology of non-communicable diseases, including asthma/wheezing disorders. We undertook a systematic review investigating risks of asthma/wheezing disorders in children born preterm, including the increasing numbers who, as a result of advances in neonatal care, now survive very preterm birth. Methods and Findings: Two reviewers independently searched seven online databases for contemporaneous (1 January 1995-23 September 2013) epidemiological studies investigating the association between preterm birth and asthma/ wheezing disorders. Additional studies were identified through reference and citation searches, and contacting international experts. Quality appraisal was undertaken using the Effective Public Health Practice Project instrument. We pooled unadjusted and adjusted effect estimates using random-effects meta-analysis, investigated 'dose-response' associations, and undertook subgroup, sensitivity, and meta-regression analyses to assess the robustness of associations. We identified 42 eligible studies from six continents. Twelve were excluded for population overlap, leaving 30 unique studies involving 1,543,639 children. Preterm birth was associated with an increased risk of wheezing disorders in unadjusted (13.7% versus 8.3%;odds ratio [OR] 1.71, 95% CI 1.57-1.87;26 studies including 1,500,916 children) and adjusted analyses (OR 1.46, 95% CI 1.29-1.65;17 studies including 874,710 children). The risk was particularly high among children born very preterm ( Conclusions: There is compelling evidence that preterm birth--particularly very preterm birth--increases the risk of asthma. Given the projected global increases in children surviving preterm births, research now needs to focus on understanding underlying mechanisms, and then to translate these insights into the development of preventive interventions. Review Registration: PROSPERO CRD42013004965 Please see later in the article for the Editors' Summary., Introduction The impact of early life exposures on subsequent health and disease is increasingly recognised [1]. Preterm birth is a common early life event, the adverse consequences of which can [...]

Kramer, Boris W., Alan H. Jobe, and Machiko Ikegami. Exogenous surfactant changes the phenotype of alveolar macrophages in mice. Am J Physiol Lung Cell Mol Physiol 280: L689-L694, 2001.--Alveolar macrophages are essential for the maintenance of surfactant homeostasis. We asked whether surfactant treatment would change alveolar macrophage number and whether the alveolar macrophage phenotype would become activated or apoptotic when challenged in vivo with exogenous surfactant. Surfactant pool size in mice was increased by repetitive surfactant treatments containing 120 mg/kg (110 [micro]mol/kg) saturated phosphatidylcholine. The number of alveolar macrophages recovered by alveolar lavage decreased after the first dose by 49% and slightly increased after the second and third doses. Up to 28.5% of the macrophages became large and foamy, and their appearance normalized within 12 h. Surfactant treatment did not increase the percent of apoptotic or necrotic cells. The alveolar macrophages were not activated as indicated by no change in expression of CD14, CD16, CD54, CD95, and scavenger receptor class A types I and II after surfactant treatment. Surfactant treatment in healthy mice transiently changed the phenotype of alveolar macrophages to large and foamy without indications of changes in the surface markers characteristic of activation. surface markers; exogenous surfactant therapy; dipalmitoylphosphatidylcholine

Intra-amniotic endotoxin increases pulmonary surfactant proteins and induces SP-B processing in fetal sheep. Am J Physiol Lung Cell Mol Physiol 280: L279-L285, 2001.--Intra-amniotic (IA) endotoxin induces lung maturation within 6 days in fetal sheep of 125 days gestational age. To determine the early fetal lung response to IA endotoxin, the timing and characteristics of changes in surfactant components were evaluated. Fetal sheep were exposed to 20 mg of Escherichia coli 055:B5 endotoxin by IA injection from 1 to 15 days before preterm delivery at 125 days gestational age. Surfactant protein (SP) A, SP-B, and SP-C mRNAs were maximally induced at 2 days. SP-D mRNA was increased fourfold at I day and remained at peak levels for up to 7 days. Bronchoalveolar lavage fluid from control animals contained very little SP-B protein, 75% of which was a partially processed intermediate. The alveolar pool of SP-B was significantly increased between 4 and 7 days in conjunction with conversion to the fully processed active airway peptide. All SPs were significantly elevated in the bronchoalveolar lavage fluid by 7 days. IA endotoxin caused rapid and sustained increases in SP mRNAs that preceded the increase in alveolar saturated phosphatidylcholine processing of SP-B and improved lung compliance in prematurely delivered lambs. lipopolysaccharide; surfactant protein B; gene regulation

Kramer, Boris W., Machiko Ikegami, and Alan H. Jobe. Surfactant phospholipid catabolic rate is pool size dependent in mice. Am J Physiol Lung Cell Mol Physiol 279: L842-L848, 2000.--We increased surfactant pool size by surfactant treatment in mice to test if the catabolism of the major component of surfactant, saturated phosphatidylcholine (Sat PC), was rate limited. By intratracheal instillation, we gave mice trace doses, doses of 45 or 110 [Mu]mol/kg, or three doses of 110 [Mu]mol/kg of Sat PC in surfactant that contained radiolabeled dipalmitoylphosphatidylcholine (DPPC) and a radiolabeled phospholipase A-resistant ether analog of DPPC. Two strains of mice with 2-fold differences in alveolar and total Sat PC pool sizes were used; the mice with the higher pool sizes had a 2.3-fold higher steady-state catabolic rate. Acute increases in alveolar surfactant given by intratracheal instillation increased catabolic rates -2-fold over the steady-state rates in both strains. There was minimal loss of the ether analog of DPPC from the lungs, and the alveolar macrophages did not accumulate more than 10% of the ether analog. In these two strains of mice, the catabolism of Sat PC was not rate limited because catabolic rate increased when alveolar pool sizes were increased. surfactant treatment; dipalmitoylphosphatidylcholine; alveolar macrophage