Effects of maternal retinoic acid administration on lung angiogenesis in oligohydramnios-exposed fetal rats.

BACKGROUND: All-trans retinoic acid (ATRA) induces in vitro angiogenesis and vascular endothelial growth factor (VEGF) secretion. Prenatal administration of vitamin A tends to increase the pulmonary and plasma levels of VEGF in the developing mouse. The aims of this study were to examine the effects of maternal retinoic acid treatment on lung VEGF expression and angiogenesis in oligohydramnios-exposed fetal rats. METHODS: On day 16 of gestation, pregnant Sprague-Dawley rats were randomly assigned to either the retinoic acid group (intragastric ATRA at 10 mg/kg body weight) or the vehicle group. We punctured each uterine sac to produce oligohydramnios, and fetuses in the opposite uterine horn served as controls. On day 21 of gestation, the fetuses were delivered by cesarean section. RESULTS: Rats exposed to oligohydramnios exhibited lower lung weights and lung/body weight ratios, and ATRA exhibited no effects on the body or lung weights of oligohydramnios-exposed rats. Lung microvessel density decreased in oligohydramnios-exposed rats of maternal vehicle-treated dams. Microvessel density was comparable between the oligohydramnios + retinoic acid group and the control + retinoic acid group. VEGF expression was comparable among control and oligohydramnios-exposed rats of maternal vehicle- or retinoic acid-treated dams. CONCLUSION: Maternal retinoic acid treatment did not increase lung VEGF expression or enhance lung development in oligohydramnios-exposed fetal rats. These results do not support the use of maternal retinoic acid to prevent oligohydramnios-induced pulmonary hypoplasia in the pseudoglandular stage.

Tissue plasminogen activator attenuates ventilator-induced lung injury in rats.

AIM: To test the hypothesis that the tissue plasminogen activator (tPA) may counteract the inhibitory effect of plasminogen activator inhibitors (PAI) and attenuate lung injury in a rat model of ventilator-induced lung injury (VILI). METHODS: Adult male Sprague-Dawley rats were ventilated with a HVZP (high-volume zero PEEP) protocol for 2 h at a tidal volume of 30 mL/kg, a respiratory rate of 25 breaths/min, and an inspired oxygen fraction of 21%. The rats were divided into 3 groups (n=7 for each): HVZP+tPA group receiving tPA (1.25 mg/kg, iv) 15 min before ventilation, HVZP group receiving HVZP+vehicle injection, and a control group receiving no ventilation. After 2 h of ventilation, the rats were killed; blood and lungs were collected for biochemical and histological analyses. RESULTS: HVZP ventilation significantly increased total protein content and the concentration of macrophage inflammatory protein-2 (MIP-2) in the bronchoalveolar lavage fluid (BALF) as well as the lung injury score. Rats that received HVZP ventilation had significantly higher lung PAI-1 mRNA expression, plasma PAI-1 and plasma D-dimer levels than the control animals. tPA treatment significantly reduced the BALF total protein and the lung injury score as compared to the HVZP group. tPA treatment also significantly decreased the plasma D-dimer levels and the HVZP ventilation-induced lung vascular fibrin thrombi. tPA treatment showed no effect on MIP-2 level in BALF. CONCLUSION: These results demonstrate that VILI increases lung PAI-1 mRNA expression, plasma levels of PAI-1 and D-dimers, lung injury score and vascular fibrin deposition. tPA can attenuate VILI by decreasing capillary-alveolar protein leakage as well as local and systemic coagulation as shown by decreased lung vascular fibrin deposition and plasma D-dimers.

Angiotensin II type 1 receptor antagonist attenuates lung fibrosis in hyperoxia-exposed newborn rats.

Bronchopulmonary dysplasia (BPD) remains a major cause of morbidity and mortality during the first year of life, and many infants have significant respiratory problems throughout childhood. Currently no effective therapy is clinically available to prevent the long-term pulmonary sequelae of BPD. Previous research has demonstrated that the renin-angiotensin system is up-regulated in human lung fibroblasts. Angiotensin II type 1 receptor (AT1R) antagonists and AT1R short interfering RNA diminished hyperoxia-increased collagen expression, whereas AT2R antagonists did not have any effects on these hyperoxia-induced changes. The in vivo therapeutic effects of AT1R antagonists on hyperoxia-induced lung fibrosis remain unknown. The present study assessed the effects of an AT1R antagonist (losartan) on preventing hyperoxia-induced lung fibrosis in newborn rats. Rat pups were exposed to 7 days of > 95% O2 and an additional 2 weeks of 60% O2. AT1R antagonist-treated pups were injected intraperitoneally with losartan at a dose of 10 mg/kg/day from postnatal days 1 to 7 and a dose of 5 mg/kg/day from postnatal days 8 to 21. Control group pups were injected with an equal volume of normal saline. AT1R antagonist treatment attenuated the hyperoxia-induced lung fibrosis on postnatal days 7 and 21 and also decreased the hyperoxia-induced expression of extracellular signal-regulated protein kinase and α-smooth muscle actin. AT1R antagonist treatment did not affect body weight or lung weight of the rats. These data suggest that AT1R antagonist may offer a novel therapeutic strategy for preventing hyperoxia-induced lung fibrosis.

Activation of the renin-angiotensin system in hyperoxia-induced lung fibrosis in neonatal rats.

BACKGROUND: Oxygen toxicity plays an important role in lung injury and may lead to bronchopulmonary dysplasia. We previously demonstrated that hyperoxia activated the renin-angiotensin system (RAS) in cultured human fetal lung fibroblasts. OBJECTIVE: To examine whether the upregulation of RAS components is associated with hyperoxia-induced lung fibrosis in neonatal Sprague-Dawley rats. METHODS: Experimental rat pups were exposed to 1 week of >95% O(2) and a further 2 weeks of 60% O(2). Control pups were exposed to room air over the same periods. Lung tissues were taken for biochemical and histochemical assays on postnatal days 7 and 21. RESULTS: Hyperoxia significantly increased total collagen content and the expression of type I collagen and alpha smooth muscle actin when compared to control rats. RAS components including angiotensinogen, angiotensin-converting enzyme, angiotensin II, and angiotensin II type 1 receptor were significantly upregulated by hyperoxia. The results also demonstrated that only the extracellular signal-regulated kinase (ERK) signaling pathway was activated by hyperoxia exposure. p38 mitogen-activated protein kinase and c-Jun N-terminal kinase were not activated. CONCLUSIONS: Local RAS activation is involved in the pathogenesis of hyperoxia-induced lung fibrosis in neonatal rats. ERK phosphorylation might mediate angiotensin II type 1 receptor activation.

Downregulation of caveolin-1 in a murine model of acute allergic airway disease.

BACKGROUND: Airway remodeling refers to the structural changes in the airways of asthma. Caveolin-1 reduces cell growth and negatively regulates smooth muscle cell proliferation. The aim was to investigate lung caveolin-1 status in a murine model of acute allergic airway disease. METHODS: Six- to eight-week-old female BALB/c mice were sensitized by intraperitoneal injections of phosphate-buffered saline or ovalbumin (OVA) and aluminium hydroxide on Days 0 and 14, challenged with aerosolized saline or OVA (1%) on Days 21-25, 28-32, and 35. The mice were killed 1 day after the last OVA/saline challenge. Serum OVA-specific immunoglobulin E (IgE) was measured by enzyme-linked immunosorbent assay. Peribronchial inflammation was quantified by morphometric analysis. Lung caveolin-1 and Type I collagen mRNA expression was determined by real-time reverse-transcription polymerase chain reaction. Total lung collagen was measured using Sircol Assay Kit. RESULTS: Serum OVA-specific IgE levels were significantly elevated in OVA-challenged mice when compared with saline-challenged mice. Percentage of inflammatory cells in the bronchoalveolar lavage was significantly higher in the OVA-challenged animals. The animals' lungs that were sensitized and challenged with OVA contained large numbers of inflammatory cells concentrated near the airways and in the perivascular areas. The thickness of the bronchial epithelial layer and smooth muscle layer and the numbers of total inflammatory cells and eosinophils significantly increased in OVA-challenged mice. Caveolin-1 mRNA expression significantly decreased and Type I collagen mRNA expression significantly increased in the lung tissue of OVA-challenged mice. CONCLUSION: These results suggest that caveolin-1 seems to be involved in the pathogenesis of airway remodeling of acute allergic airway disease.

Maternal baicalin treatment increases fetal lung surfactant phospholipids in rats.

Baicalin is a flavonoid compound purified from the medicinal plant Scutellaria baicalensis Georgi and has been reported to stimulate surfactant protein (SP)-A gene expression in human lung epithelial cell lines (H441). The aims of this study were to determine whether maternal baicalin treatment could increase lung surfactant production and induce lung maturation in fetal rats. This study was performed with timed pregnant Sprague-Dawley rats. One-day baicalin group mothers were injected intraperitoneally with baicalin (5 mg/kg/day) on Day 18 of gestation. Two-day baicalin group mothers were injected intraperitoneally with baicalin (5 mg/kg/day) on Days 17 and 18 of gestation. Control group mothers were injected with vehicle alone on Day 18 of gestation. On Day 19 of gestation, fetuses were delivered by cesarean section. Maternal treatment with 2-day baicalin significantly increased saturated phospholipid when compared with control group and total phospholipid in fetal lung tissue when compared with control and 1-day baicalin groups. Antenatal treatment with 2-day baicalin significantly increased maternal growth hormone when compared with control group. Fetal lung SP-A mRNA expression and maternal serum corticosterone levels were comparable among the three experimental groups. Maternal baicalin treatment increases pulmonary surfactant phospholipids of fetal rat lungs and the improvement was associated with increased maternal serum growth hormone. These results suggest that antenatal baicalin treatment might accelerate fetal rat lung maturation.

The renin-angiotensin system mediates hyperoxia-induced collagen production in human lung fibroblasts.

A high concentration of oxygen can cause lung injury and lead to pulmonary fibrosis. Angiotensin (Ang) II induces human lung fibroblast proliferation and stimulates collagen synthesis. However, the role of the renin-angiotensin system (RAS) in the pathogenesis of hyperoxia-induced collagen production is unclear. The aims of this study were to investigate the effects of hyperoxia on the components of the RAS and collagen expression in human lung fibroblasts (MRC-5). Hyperoxia increased total collagen, collagen type I, and alpha-smooth muscle actin (alpha-SMA) mRNA and protein expression. RAS components and Ang II production were also significantly increased after hyperoxic exposure. Hyperoxia induced Ang II type 1 receptor (AT1R) expression but did not alter AT2R expression, furthermore, silencing of AT1R signaling with small interfering RNA suppressed hyperoxia-induced phosphorylated-ERK (p-ERK) 1/2, alpha-SMA, and collagen type I expression. Ang II increased p-ERK 1/2 and collagen type I expression, and these increases were inhibited by the AT1R inhibitor, losartan, but not by the AT2R inhibitor, PD123319 under both normoxic and hyperoxic conditions. These data suggest Ang II-mediated signaling transduction via AT1R is involved in hyperoxia-induced collagen synthesis in human lung fibroblasts.

Effects of activated protein C on ventilator-induced lung injury in rats.

BACKGROUND: Mechanical ventilation with a high tidal volume (VT) increases lung and systemic plasminogen activator inhibitor (PAI)-1 levels and alveolar fibrin deposition. Activated protein C (APC) may decrease PAI activity in endothelial cell-conditioned medium and thus enhance fibrinolysis. OBJECTIVES: The aims of this study were to test the hypothesis that APC can neutralize PAI-1 activity and improve lung function in an animal model of ventilator-induced lung injury. METHODS: Rats were ventilated with a high-volume zero positive end-expiratory pressure (PEEP; HVZP) protocol by a volume-cycled ventilator for 2 h at a VT of 30 ml/kg, a respiratory rate of 25 breaths/min, and an FiO(2) of 0.21. Fifteen minutes before ventilation, the rats received intravenous APC (250 microg/kg, HVZP+APC group) or normal saline (vehicle; HVZP group). Another group that received no ventilation served as the control group. RESULTS: Levels of arterial blood gas tension were comparable between the two ventilation groups throughout the study period. Rats treated with the HVZP protocol exhibited significantly higher total protein and macrophage inflammatory protein-2 concentrations in bronchoalveolar lavage fluid (BALF) and higher lung PAI-1 mRNA expression and plasma active PAI-1 levels than did the control group. Administration of APC tended to reduce the BALF protein content and systemic PAI-1 activity but did not improve the lung histology in the HVZP+APC group. Plasma levels of D-dimers were comparable among the three study groups. CONCLUSIONS: These results suggest that APC administered at a higher dosage might improve lung function by reducing alveolar protein leakage and systemic coagulation.

Chymase mediates paraquat-induced collagen production in human lung fibroblasts.

Survivors of paraquat poisoning may be left with pulmonary fibrosis and a restrictive type of pulmonary dysfunction. Chymase converts angiotensin (Ang) I to Ang II, which is closely involved with lung fibrosis. The role played by chymase in paraquat-induced lung fibrosis is unclear. We examined the effects of paraquat on chymase, renin-angiotensin system components, and collagen expression in murine and human lung fibroblasts (MRC-5). Lung chymase and collagen type I mRNA and protein expression were significantly increased and angiotensin-converting enzyme (ACE) mRNA and protein expression were comparable between the control and paraquat-treated mice 1 and 3 weeks after administration. Paraquat significantly upregulated angiotensinogen mRNA expression in a dose-dependent manner while ACE activity and protein expression were similar in MRC-5 cells. Furthermore, paraquat enhanced Ang II and collagen type I mRNA and protein expression, alpha-smooth muscle actin, and chymase protein and chymase small interfering RNA inhibited these effects. The cDNA sequence of chymase in MRC-5 cells is identical to that in human mast cells. This study found increased chymase expression in paraquat-treated human lung fibroblasts and confirmed in vitro and in an in vivo paraquat model of lung fibrosis that chymase generates Ang II and enhances collagen expression. These data suggest a role for chymase in the pathogenesis of paraquat-induced lung fibrosis.

Paraquat increases connective tissue growth factor and collagen expression via angiotensin signaling pathway in human lung fibroblasts.

Survivors of paraquat poisoning are left with pulmonary fibrosis which results in a restrictive type of long-term pulmonary dysfunction. Connective tissue growth factor (CTGF) is a key growth factor that initiates tissue repair and underlies the development of lung fibrosis. Angiotensin (ANG) II may induce CTGF expression in the heart and kidney and plays an important role in the pathogenesis of lung fibrosis. The biological effects of ANG II are mediated by ANG II type 1 receptor (AT1R) and AT2R. The aims of this study were to investigate the effects of paraquat on ANG II, ANG II receptors, CTGF, and collagen expressions and to assess the role of ANG II receptors in paraquat-induced collagen synthesis in human lung fibroblasts (MRC-5). MRC-5 cells were incubated with various concentrations of paraquat with or without the ANG II receptor antagonist, saralasin. Paraquat increased ANG II production and AT1R mRNA and protein expression and decreased AT2R mRNA expression. Furthermore, paraquat treatment increased CTGF and collagen mRNA and protein expression in a dose-dependent manner and saralasin inhibited these effects. These results indicate that paraquat increases CTGF and collagen expression by activating angiotensin signaling pathway in human lung fibroblasts.

Curcuminoids suppress the growth of pharynx and nasopharyngeal carcinoma cells through induced apoptosis.

Nasopharyngeal carcinoma (NPC) is one of the common malignant cancers in China, and radiotherapy or chemotherapy is the main therapy method for NPC. Curcuminoids (or curcumin), natural antioxidants, have been recently shown to produce a potent chemopreventive action against several types of cancer. They have also displayed antioxidant and anti-inflammatory activities. In the present study, the antiproliferation and induced apoptosis effects of curcuminoids have been investigated in Detroit 562 cells (human pharynx carcinoma) and HONE-1 (human nasopharyngeal carcinoma) cells. Results indicated that curcuminoids have produced an inhibition of cell proliferation as well as the activation of apoptosis in these cancer cells. Both effects were observed to increase in proportion with the dose of curcuminoids. The DNA fragmentation, caspase-3 activation,and NF-kappaB transcriptional factor activity have been studied. By these approaches, apoptosis was induced by curcuminoids in the pharynx and nasopharyngeal cancer cells via caspase-3-dependent pathway. However, a different dependency has been observed, whereas proliferation inhibition and apoptosis depend upon the amount of curcuminoid treatment in the cancer cells.

Experimental oligohydramnios decreases collagen in hypoplastic fetal rat lungs.

Neonates with premature rupture of the membrane and oligohydramnios have an increased risk of acute respiratory morbidity. The aims of this study are to investigate the effects of experimental oligohydramnios on transforming growth factor (TGF)-beta1 and connective tissue growth factor (CTGF) expressions and collagen level in fetal rat lungs. On day 16 of gestation, we anesthetized timed pregnant Sprague-Dawley dams, punctured the uterine wall and fetal membranes of each amniotic sac which resulted in oligohydramnios. Fetuses in the opposite uterine horn served as controls. On days 19 and 21 of gestation, fetuses were delivered by cesarean section. Rats exposed to oligohydramnios exhibited significantly lower lung weight/body weight ratios on days 19 and 21 of gestation than did the control rats. Lung type I collagen and TGF-beta1 mRNA expressions and lung collagen levels were significantly decreased in rats exposed to oligohydramnios on days 19 and 21 of gestation. Type I collagen and inhibitors of metalloproteinase-1 (TIMP-1) proteins were decreased and matrix metalloproteinase-1 (MMP-1) was increased in oligohydramnios-exposed rats on days 19 and 21 of gestation. CTGF mRNA expressions were comparable between control and oligohydramnios-exposed rats on days 19 and 21 of gestation. These data suggest that downregulation of collagen might be involved in the pathogenesis of oligohydramnios-induced respiratory morbidity.

Captopril decreases plasminogen activator inhibitor-1 in rats with ventilator-induced lung injury.

OBJECTIVE: To test the hypotheses that high tidal-volume ventilation increases plasminogen activator inhibitor (PAI)-1, and the angiotensin-converting enzyme inhibitor, captopril (CAP), may attenuate these effects. SETTING: University research facility. SUBJECTS: Twenty adult male Sprague-Dawley rats. INTERVENTIONS: All rats were randomized to receive two ventilation strategies for 2 h: 1) a high-volume zero positive end-expiratory pressure (PEEP) (HVZP) group at a tidal volume of 40 mL/kg, a respiratory rate of 25 breaths/min, and an FiO2 of 0.21; and 2) an HVZP + CAP group which received an intraperitoneal injection of CAP (100 mg/kg) 30 min before HVZP ventilation. Another group that was not subjected to ventilation served as the control. MEASUREMENTS AND MAIN RESULTS: Total protein recovered from bronchoalveolar lavage fluid was significantly higher in rats ventilated with the HVZP protocols than in control rats. Rats treated with HVZP ventilation had significantly higher lung angiotensin (ANG) II and PAI-1 messenger RNA expression levels and a higher plasma active PAI-1 level than did the control and HVZP + CAP groups. Lung ANG II levels were positively correlated with plasma PAI-1. Representative lung tissue of the HVZP + CAP group showed mild inflammatory cell infiltration and less hemorrhage and fibrin deposition than did the HVZP group. The HVZP and HVZP + CAP groups had significantly higher lung injury scores than did the control group and rats treated with HVZP + CAP ventilation exhibited significantly lower lung injury scores than did the HVZP group. CONCLUSIONS: Mechanical ventilation with a high tidal volume and no PEEP increases alveolar fibrin deposition and systemic PAI-1 activity, which are attenuated by captopril, an angiotensin-converting enzyme inhibitor. These results imply that local ANG II is involved in the pathogenesis of disordered coagulation in ventilator-induced lung injury (VILI) and suggest that the protective mechanism of captopril's attenuation of VILI is related to a reduction in PAI-1.

Effects of maternal undernutrition on renal angiotensin II and chymase in hypertensive offspring.

Intrauterine growth restriction (IUGR) can program the future development of hypertension in adulthood. The renin-angiotensin system has been reported to play a role in IUGR-induced hypertension. The aims of this study were to investigate the effects of IUGR on renal angiotensin-converting enzyme (ACE), angiotensin II (Ang II) and chymase in IUGR-induced hypertension. Timed pregnant Sprague-Dawley rats received 50% rations of control food intakes from days 15 to 21 of gestation. Control rats received regular food throughout the pregnancies. Arterial blood pressure and glomerular number were measured and immunohistochemical studies were performed on kidney tissues in adult male offspring at 16 weeks of age. IUGR rats exhibited significantly lower body and kidney weights and reduced number of glomeruli when compared with control rats. IUGR rats had significantly higher systolic blood pressure than control rats. Immunoreactivity of ACE was comparable between control and IUGR rats whereas immunoreactivities of chymase and Ang II were significantly higher in IUGR rats than in control rats. In conclusion, immunohistochemical studies document up-regulation of ACE-independent Ang II and chymase in IUGR kidney and indicate that overactivity of chymase may result in increased intrarenal Ang II production, which could contribute to the development of hypertension in intrauterine undernourished rats.

Retinoic acid fails to reverse oligohydramnios-induced pulmonary hypoplasia in fetal rats.

All-trans retinoic acid (ATRA) stimulates platelet-derived growth factor (PDGF)-A expression and enhances alveolarization in rat lungs. On d 16 of gestation, pregnant Sprague-Dawley rats were randomly assigned to either a retinoic acid group (intragastric ATRA at 10 mg/kg body weight) or a vehicle group. We punctured each amniotic sac, and fetuses in the opposite uterine horn served as controls. On d 21 of gestation, the fetuses were delivered by cesarean section. Rats subjected to oligohydramnios exhibited significantly lower lung weights and lung/body weight ratios, and ATRA had no effects on the body or lung weights of oligohydramnios-exposed rats. Lung PDGF-A and -B mRNA expression was significantly lower in oligohydramnios-exposed rats compared with control littermates of maternal vehicle-treated dams. Maternal retinoic acid treatment significantly increased PDGF-A and -B mRNA expression in control and oligohydramnios-exposed rats compared with all rats and oligohydramnios-exposed rats of maternal vehicle-treated dams, respectively. Rats exposed to oligohydramnios exhibited a significantly lower generation of alveolar saccules than did control rats in the maternal retinoic acid- and vehicle-treated groups. In this model, maternal retinoic acid treatment showed no positive effects on oligohydramnios-induced pulmonary hypoplasia in the pseudoglandular stage.

Effects of maternal undernutrition on lung growth and insulin-like growth factor system expression in rat offspring.

BACKGROUND: Maternal undernutrition may alter the development of the lung structure in rat offspring. METHODS: We investigated the effects of maternal undernutrition (50% rations of the control food intake) during the last week of gestation on the expression of the rat lung insulin-like growth factor (IGF) system in the postnatal period. RESULTS: Body weights of undernourished pregnant rats were significantly lower than those of control rats from gestational days 16 to 21. Rats subjected to intrauterine growth restriction (IUGR) exhibited significantly lower body weights and lower lung weights on postnatal days 1, 7, 14, and 28 and lower lung/body weight ratios on postnatal days 7 and 14 when compared with control rats. Lung IGF-I, IGF-II, IGF receptors types 1 (IGFR-1) and 2 (IGFR-2), and the IGF binding protein (IGFBP) mRNA expressions increased as rats aged and reached a peak on postnatal day 14. Maternal undernutrition significantly increased IGF-I and IGF-II mRNA expressions on postnatal days 1 and 28. Lung IGFR-1, IGFR-2, and IGFBP mRNA expressions were similar between control and IUGR rats during the study period. CONCLUSIONS: This study presents a comprehensive overview of lung IGF system expression in control and IUGR rats and demonstrates the developmental regulation of each component.

Up-regulation of connective tissue growth factor in hyperoxia-induced lung fibrosis.

Pulmonary oxygen toxicity plays an important role in the lung injury process that leads to the development of bronchopulmonary dysplasia. Connective tissue growth factor (CTGF) is a fibroblast mitogen and promoter of collagen deposition. We investigated the effects of postnatal hyperoxia on lung collagen and CTGF expression in rats. Rat pups were exposed to 7 d of >95% O2 and a further 3 wk of 60% O2. CTGF mRNA and protein expression increased after hyperoxia treatment, and the values were significantly higher in hyperoxia-exposed rats on postnatal d 7 and 14. Lung collagen levels increased as rats aged, and the values were comparable between room air-exposed and hyperoxia-exposed rats on postnatal d 7 and 14 and were significantly higher in hyperoxia-exposed rats on postnatal d 21 and 28. Increases in CTGF mRNA and protein expressions preceded the onset of increased lung collagen. These data demonstrate that CTGF is up-regulated at time points preceding the fibrotic phase of the lung injury adding credence to the hypothesis that CTGF seems to be involved in the pathogenesis of hyperoxia-induced lung fibrosis and an anti-CTGF strategy might attenuate hyperoxia-induced lung fibrosis.

Oligohydramnios decreases platelet-derived growth factor expression in fetal rat lungs.

OBJECTIVE: To evaluate the effects of experimental oligohydramnios on lung growth, expression of platelet-derived growth factor (PDGF) and its receptors, and lung morphology in fetal rats. METHODS: On day 16 of gestation, we anesthetized timed pregnant Sprague-Dawley dams and punctured uterine wall and fetal membranes of each uterine sac which resulted in oligohydramnios. The fetuses in the opposite uterine horn served as controls. On days 19 and 21 of gestation, the fetuses were delivered by cesarean section and weighed, and the lungs were dissected free and weighed. RESULTS: Rats exposed to oligohydramnios exhibited significantly lower lung/body weight ratios on days 19 and 21 of gestation and significantly lower radial saccular counts on day 21 of gestation than did the control rats. Lung PDGF-A and PDGF-B gene and protein expression and elastin level were significantly decreased in rats exposed to oligohydramnios on days 19 and 21 of gestation. The PDGF receptor alpha and beta gene expression levels were significantly decreased in rats exposed to oligohydramnios on day 19 of gestation. CONCLUSION: A decreased PDGF expression may be important in the pathogenesis of oligohydramnios-induced pulmonary hypoplasia and suggests that supplementation may provide useful therapeutic strategies.

High-dose vascular endothelial growth factor increases surfactant protein gene expressions in preterm rat lung.

AIMS: To investigate the effects of intra-amniotic vascular endothelial growth factor (VEGF) treatment on surfactant pool sizes and surfactant protein (SP) gene expressions in fetal rat lung. METHOD: On the 18th day of gestation, an abdominal midline incision was performed on timed pregnant Sprague-Dawley rats and the two uterine horns were exposed. VEGF (2.5 microg or 5.0 microg) and saline were injected into the amniotic cavity of the left and right uterine horns, respectively. On the 19th day of gestation, fetuses were delivered by caesarean section. RESULTS: We analyzed the data between the fetuses within the same dam in each group. Mean fetal body weight and lung tissue saturated phosphatidylcholine and total phospholipids were comparable between control and VEGF-treated rats at each VEGF dosage. Lung SP mRNA expressions were comparable between control and VEGF 2.5 microg-treated rats. VEGF 5.0 microg treatment increased lung SP mRNA expressions and the values were statistically significant for SP-B and SP-D mRNAs when compared with the control rats. CONCLUSIONS: These results suggest that VEGF might have potential therapeutic implications in enhancing fetal lung maturation.

Nitric oxide in the pathogenesis of diffuse pulmonary fibrosis.

By studying the responses of nitric oxide in pulmonary fibrosis, the role of inducible nitric oxide synthase in diffuse pulmonary fibrosis as caused by lipopolysaccharide (LPS) treatment was investigated. When compared to rats treated with LPS only, the rats pretreated with 1400W (an iNOS-specific inhibitor) were found to exhibit a reduced level in: (i) NOx (nitrate/nitrite) production, (ii) collagen type I protein expression, (iv) soluble collagen production, and (iv) the loss of body weight and carotid artery PO2. In the pulmonary fibroblast culture, exogenous NO from LPS-stimulated secretion by macrophages or from a NO donor, such as DETA NONOate, was observed to induce the expression of TIMP-1, HSP47, TGF-beta1, and collagen type I as well as the phosphorylation of SMAD-2. After inhalation of NO for 24 h, an up-regulation of collagen type I protein was also noted to occur in rat pulmonary tissue. The results suggest that the NO signal pathway enhanced the expression of TGF-beta1, TIMP-1, and HSP47 in pulmonary fibroblasts, which collectively demonstrate that the NO signal pathway could activate the SMAD-signal cascade, by initiating a rapid increase in TGF-beta1, thereby increasing the expression of TIMP-1 and HSP47 in pulmonary fibroblasts, and play an important role in pulmonary fibrosis.