SFTA2--a novel secretory peptide highly expressed in the lung--is modulated by lipopolysaccharide but not hyperoxia.

Tissue-specific transcripts are likely to be of importance for the corresponding organ. While attempting to define the specific transcriptome of the human lung, we identified the transcript of a yet uncharacterized protein, SFTA2. In silico analyses, biochemical methods, fluorescence imaging and animal challenge experiments were employed to characterize SFTA2. Human SFTA2 is located on Chr. 6p21.33, a disease-susceptibility locus for diffuse panbronchiolitis. RT-PCR verified the abundance of SFTA2-specific transcripts in human and mouse lung. SFTA2 is synthesized as a hydrophilic precursor releasing a 59 amino acid mature peptide after cleavage of an N-terminal secretory signal. SFTA2 has no recognizable homology to other proteins while orthologues are present in all mammals. SFTA2 is a glycosylated protein and specifically expressed in nonciliated bronchiolar epithelium and type II pneumocytes. In accordance with other hydrophilic surfactant proteins, SFTA2 did not colocalize with lamellar bodies but colocalized with golgin97 and clathrin-labelled vesicles, suggesting a classical secretory pathway for its expression and secretion. In the mouse lung, Sfta2 was significantly downregulated after induction of an inflammatory reaction by intratracheal lipopolysaccharides paralleling surfactant proteins B and C but not D. Hyperoxia, however, did not alter SFTA2 mRNA levels. We have characterized SFTA2 and present it as a novel unique secretory peptide highly expressed in the lung.

Systemic hypothermia after neonatal encephalopathy: outcomes of neo.nEURO.network RCT.

OBJECTIVE: Mild hypothermia after perinatal hypoxic-ischemic encephalopathy (HIE) reduces neurologic sequelae without significant adverse effects, but studies are needed to determine the most-efficacious methods. METHODS: In the neo.nEURO.network trial, term neonates with clinical and electrophysiological evidence of HIE were assigned randomly to either a control group, with a rectal temperature of 37°C (range: 36.5-37.5°C), or a hypothermia group, cooled and maintained at a rectal temperature of 33.5°C (range: 33-34°C) with a cooling blanket for 72 hours, followed by slow rewarming. All infants received morphine (0.1 mg/kg) every 4 hours or an equivalent dose of fentanyl. Neurodevelopmental outcomes were assessed at the age of 18 to 21 months. The primary outcome was death or severe disability. RESULTS: A total of 129 newborn infants were enrolled, and 111 infants were evaluated at 18 to 21 months (53 in the hypothermia group and 58 in the normothermia group). The rates of death or severe disability were 51% in the hypothermia group and 83% in the normothermia group (P=.001; odds ratio: 0.21 [95% confidence interval [CI]: 0.09-0.54]; number needed to treat: 4 [95% CI: 3-9]). Hypothermia also had a statistically significant protective effect in the group with severe HIE (n=77; P=.005; odds ratio: 0.17 [95% CI: 0.05-0.57]). Rates of adverse events during the intervention were similar in the 2 groups except for fewer clinical seizures in the hypothermia group. CONCLUSION: Systemic hypothermia in the neo.nEURO.network trial showed a strong neuroprotective effect and was effective in the severe HIE group.

Mechanical ventilation with high tidal volume or frequency is associated with increased expression of nerve growth factor and its receptor in rabbit lungs.

OBJECTIVE: Nerve growth factor (NGF), a neurotrophin, is induced in lung cells by proinflammatory cytokines, and has a role in bronchial hyperreactivity and lung tissue repair. Ventilation induced lung injury, on the other hand, is known to increase the levels of proinflammatory cytokines in the lungs. We investigated whether, and to what extent, various degrees of lung injury induced by short-term ventilation affect NGF levels in the lung tissue of adolescent rabbits. METHODS: The rabbits were randomized to different modes of ventilation: (1) CON: normal ventilation for 30 min; (2) NVT: normal ventilation for 6 hr; (3) HFQ: ventilation for 6 hr at double frequency, but normal tidal volume (VT); and (4) HVT: 6 hr ventilation at double VT but normal frequency. RESULTS: NGF protein was detected in bronchoalveolar lavage fluid (BALF) and lung tissue in all animals. Ventilation for 6 hr significantly increased NGF levels, in both BALF and lung tissue, in the HFQ and HVT groups as compared to control (P < 0.05). The maximum increase in BALF NGF was seen in the HVT group (P = 0.02 vs. CON and NVT groups, and P = 0.05 vs. HFQ). A parallel increase in interleukin 1-beta (IL1-beta) was observed. Expression of the high-affinity NGF-receptor, tropomyosin-related kinase A (TrkA), was also upregulated in these two groups. CONCLUSION: Injurious modes of mechanical ventilation upregulate NGF and its receptor TrkA in rabbit lungs, and IL1-beta may be a mediator for this response. We speculate that this increase in NGF level may translate into the development of bronchial hyperreactivity.

Effects of duration and amount of lung stretch at biophysical, biochemical, histological, and transcriptional levels in an in vivo rabbit model of mild lung injury.

The purpose of this study was to characterize the effects of doubling minute ventilation (either by doubling ventilator frequency [Freq] or tidal volume [V T]) and of normal minute ventilation prolonged to 12-fold duration, synchronously at biophysical, biochemical/cellular, histological, and transcriptional levels in a model of mild lung injury. A prospective, randomized study was performed on adolescent New-Zealand white rabbits. The rabbits were randomly assigned to one of the following groups: control (normal minute ventilation for 0.5 hours); 1 x V T, 12-fold prolongation at normal V T (normal minute ventilation for 6 hours [12 x 0.5 hours]); 2 x Freq at normal V T (double minute ventilation for 6 hours); and 2 x V T at normal Freq (double minute ventilation for 6 hours). Normocapnia was maintained throughout the experiment. At the biophysical level, gas exchange (alveolar-arterial O2-tension difference [ AaDO2]) deteriorated by 23, 51, and 95%, and respiratory compliance decreased by 6.0, 18.4, and 26% in the 1 x V T, 2 x Freq, and 2 x V T group, respectively, during 6 hours of ventilation. Concomitantly, at the biochemical-cellular level, interleukin-8 (IL-8) in the bronchoalveolar lavage fluid increased 44-fold, 150-fold, and 275-fold ( P = 0.02), respectively. The white blood cell count decreased significantly in all three intervention groups. At the histological level, the influx of leukocytes as well as the tissue water content increased in proportion to the degree of injury. At the transcriptional level, lung IL-8 mRNA expression increased 11-fold in the 2 x V T group ( P = 0.002), 9-fold ( P = 0.02) in the 2 x Freq group, and 4-fold in the 1 x V T group as compared with control. Not only doubling V T, but also doubling Freq at normal V T injures the lung significantly, although to a lesser extent. A concept of weighted risk for increases of V T and Freq is proposed.