OBJECTIVETo investigate the effects of maternally administered dexamethasone and ambroxol on the mRNA levels of surfactant proteins (SP-A, SP-B and SP-C) expression in fetal rat lungs at gestational age day 19.

METHODSA 19-day fetal rat lung model was employed. In situ hybridization was used to detect the expression of SP-B mRNA in alveolar type II cell, and the levels of SP-A, SP-B and SP-C mRNAs were detected by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS(1) SP-B mRNA was detected in situ in alveolar type II cells in fetal rat lung of day 19 gestational age; (2) In the late developmental period of fetal rat lungs, alveolar type II cells were also found around bronchus; (3) Comparing to beta-actin mRNA, the relative values of SP-A, SP-B and SP-C mRNAs were 0.81 +/- 0.26, 0.97 +/- 0.20 and 0.88 +/- 0.11 in fetal lung in the control group. The relative values of mRNAs of SP-A, SP-B and SP-C to beta-actin were 1.04 +/- 0.16, 1.28 +/- 0.29, 1.09 +/- 0.25 in fetal lungs of the ambroxol injected rats, and were 1.08 +/- 0.25, 1.23 +/- 0.35, 1.21 +/- 0.25 in fetal lungs of the dexamethasone injected rats, respectively. Both ambroxol and dexamethasone-treated rats had significantly higher mRNA expression of surfactant proteins compared to the control saline injected animals (P < 0.05). (4) There were no significant differences between ambroxol and dexamethasone in the effects of increasing expressions of surfactant protein mRNAs (P > 0.05).

CONCLUSIONAntepartum administration of both ambroxol and dexamethasone can significantly increase fetal lung SP-A, SP-B and SP-C mRNAs expression.

Ambroxol ; pharmacology ; Animals ; Dexamethasone ; pharmacology ; Expectorants ; pharmacology ; Female ; Gene Expression Regulation, Developmental ; drug effects ; Glucocorticoids ; pharmacology ; Lung ; drug effects ; embryology ; metabolism ; Pregnancy ; Pulmonary Surfactant-Associated Protein A ; genetics ; Pulmonary Surfactant-Associated Protein B ; genetics ; Pulmonary Surfactant-Associated Protein C ; genetics ; Pulmonary Surfactant-Associated Proteins ; genetics ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar ; Reverse Transcriptase Polymerase Chain Reaction

PURPOSE: Recently, Forkhead box M1 (FoxM1) was reported to be correlated with lung maturation and expression of surfactant proteins (SPs) in mice models. However, no study has been conducted in rabbit lungs despite their high homology with human lungs. Thus, we attempted to investigate serial changes in the expressions of FoxM1 and SP-A/B throughout lung maturation in rabbit fetuses. MATERIALS AND METHODS: Pregnant New Zealand White rabbits were grouped according to gestational age from 5 days before to 2 days after the day of expected full term delivery (F5, F4, F3, F2, F1, F0, P1, and P2). A total of 64 fetuses were enrolled after Cesarean sections. The expressions of mRNA and proteins of FoxM1 and SP-A/B in fetal lung tissue were tested by quantitative reverse-transcriptase real-time PCR and Western blot. Furthermore, their correlations were analyzed. RESULTS: The mRNA expression of SP-A/B showed an increasing tendency positively correlated with gestational age, while the expression of FoxM1 mRNA and protein decreased from F5 to F0. A significant negative correlation was found between the expression levels of FoxM1 and SP-A/B (SP-A: R=-0.517, p=0.001; SP-B: R=-0.615, p<0.001). CONCLUSION: Preterm rabbits demonstrated high expression of FoxM1 mRNA and protein in the lungs compared to full term rabbits. Also, the expression of SP-A/B was inversely related with serial changes in FoxM1 expression. This is the first report to suggest an association between FoxM1 and expression of SP-A/B and lung maturation in preterm rabbits.
Animals ; Blotting, Western ; Female ; Fetus/*metabolism ; Forkhead Transcription Factors/*metabolism ; Lung/*metabolism ; Pregnancy ; Pulmonary Surfactant-Associated Protein A/genetics/*metabolism ; Rabbits

OBJECTIVETo review the pathophysiology, evaluation, management, and outcomes of children with inherited disorders of surfactant metabolism due to mutations in the genes encoding surfactant proteins-B or -C (SFTPB, SFTPC), ATP binding cassette member A3 (ABCA3), and thyroid transcription factor (NKX2.1).

DATA SOURCESReview of the literature, previous work from the author's and collaborators' laboratories, St. Louis Children's Hospital Lung Transplant Database.

STUDY SELECTIONKey articles in the field, author's work.

RESULTSInherited disorders of surfactant metabolism present as acute, severe respiratory dysfunction in the neonatal period (SFTPB, ABCA3, NKX2.1) or as chronic respiratory insufficiency in later infancy and childhood which is of variable onset, severity, and course (SFTPC, ABCA3, NKX2.1). Diagnosis is established with sequencing the relevant genes; lung biopsy with electron microscopy is a useful adjunct. For surfactant protein-B and ABCA3 deficiency presenting with acute neonatal disease, treatment options are limited to lung transplantation or compassionate care. For the more chronic presentations of surfactant protein-C, ABCA3, and NKX2.1 associated disease, the natural history is variable and therefore individualized, supportive care is appropriate,

CONCLUSIONSInherited disorders of surfactant metabolism are rare, but informative diseases that provide unique opportunities for understanding mechanisms of respiratory disease in newborns and children.

ATP-Binding Cassette Transporters ; genetics ; Humans ; Infant, Newborn ; Lung Diseases ; diagnosis ; etiology ; therapy ; Lung Transplantation ; Mutation ; Pulmonary Surfactant-Associated Protein B ; deficiency ; genetics ; Pulmonary Surfactant-Associated Protein C ; genetics ; Pulmonary Surfactants ; metabolism

OBJECTIVENeonatal asphyxia is one of the main causes for the acute respiratory distress syndrome (ARDS) in full-term newborns. Now it is believed that the reduced amount and abnormal function of pulmonary surfactant due to various causes is a major factor leading to acute lung injury. This study aimed at using an intrauterine acute ischemic-hypoxia rat model and investigating the effect of intrauterine acute ischemic-hypoxia on the expression of surfactant protein A (SP-A) and surfactant protein B (SP-B) in neonatal rat lungs.

METHODSThe rat model of acute intrauterine ischemic-hypoxia was established by ligating the unilateral uterine horn vessels of Wistar rats at the 21st gestational day. While the rat pups from the other side of the uterus, of which the uterine horn vessel was not ligated, were the sham-operation group. Rat pups were delivered by cesarean section at the 20, 30 and 40 min following the ischemic-hypoxia insult. The rat pups delivered by cesarean section from the gestation of 21 days were the normal control group. There were 42 rat pups and 6 pups in each group in this study. The distribution of SP-B protein in the neonatal rat lungs of different period of ischemia was examined by using SABC method. The average gray value of SP-B staining in type II alveolar epithelial cells were measured by Universal Imaging Porporation with Meta Morph software. The reverse transcription polymerase chain reaction (RT-PCR) was performed to quantitate the expression of SP-A and SP-B mRNA.

RESULTSFollowing the intrauterine acute ischemic-hypoxia, the numbers of type II alveolar epithelial cells with the positive SP-B staining were markedly declined. The average gray values at the 20, 30 and 40 min after the ischemia were 78.89 +/- 1.08, 79.69 +/- 0.13 and 80.00 +/- 0.63, respectively, which increased significantly compared with the normal control group (76.13 +/- 0.43, P < 0.01). The expression of SP-A and SP-B mRNA was weak following the ischemic-hypoxia insult. The relative amounts of SP-A (1.16 +/- 0.06, 1.14 +/- 0.01 and 1.13 +/- 0.04, respectively) and SP-B (0.81 +/- 0.02, 0.78 +/- 0.02 and 0.79 +/- 0.04, respectively) at the 20, 30 and 40 min after the ischemia were reduced significantly compared with controls (1.27 +/- 0.09 and 0.89 +/- 0.06, respectively, P < 0.05 and < 0.01) and reduced gradually following the prolongation of the insult. There were no significant differences (P > 0.05) between the normal and sham operation control groups on the expressions of SP-B protein as well as the SP-A and SP-B mRNA.

CONCLUSIONThe reduced synthesis of SP-B protein and the reduced expression of SP-A and SP-B mRNA might be caused by intrauterine acute ischemic-hypoxia, which may support theoretically the early application of pulmonary surfactant including SP-A and SP-B for treating the lung injuries of asphyxia in newborns.

Animals ; Animals, Newborn ; Female ; Gene Expression ; Hypoxia ; physiopathology ; Ischemia ; physiopathology ; Lung ; metabolism ; Pregnancy ; Pulmonary Surfactant-Associated Protein A ; genetics ; Pulmonary Surfactant-Associated Protein B ; genetics ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar ; Reverse Transcriptase Polymerase Chain Reaction ; Uterus ; blood supply

Pulmonary surfactant (PS) is synthesized and secreted by alveolar epithelial type II (AEII) cells, which is a complex compound formed by proteins and lipids. Surfactant participates in a range of physiological processes such as reducing the surface tension, keeping the balance of alveolar fluid, maintaining normal alveolar morphology and conducting host defense. Genetic disorders of the surfactant homeostasis genes may result in lack of surfactant or cytotoxicity, and lead to multiple lung diseases in neonates, children and adults, including neonatal respiratory distress syndrome, interstitial pneumonia, pulmonary alveolar proteinosis, and pulmonary fibrosis. This paper has provided a review for the functions and processes of pulmonary surfactant metabolism, as well as the connection between disorders of surfactant homeostasis genes and lung diseases.
ATP-Binding Cassette Transporters ; genetics ; DNA-Binding Proteins ; genetics ; Homeostasis ; Humans ; Lung Diseases ; genetics ; Pulmonary Surfactant-Associated Protein C ; genetics ; Pulmonary Surfactants ; metabolism ; Transcription Factors

Cell Line ; Clustered Regularly Interspaced Short Palindromic Repeats ; genetics ; DNA ; metabolism ; Deoxyribonuclease I ; metabolism ; Embryonic Stem Cells ; cytology ; metabolism ; Homologous Recombination ; Humans ; Pulmonary Surfactant-Associated Protein C ; genetics

OBJECTIVETo explore dysfunction mechanism of rat alveolar type II (AT-II) injured by bleomycin (BLM).

METHODSSD rats were injected with a single intratracheal dose of bleomycin or control saline. On day 7, 14, and 28 following intratracheal bleomycin or saline instillation, animals were killed under overdose of 1.5% sodium pentobarbital (0.25 ml/100 g, i.p.) and bronchoalveolar lavage fluid (BALF) from the lung was tested for the activity of pulmonary surfactant (PS) by the Whihelmy Film Balance. Several concentrations of bleomycin stimulated the culture of rat AT-II cells, and surfactant protein (SP) A, B, and aquaporin-1 (AQP) mRNA were analyzed by fluorescent quantitative polymerase chain reaction (FQ-PCR).

RESULTSThe activity of PS and hypoxemia significantly decreased on day 7 and improved on day 14 and completely recovered to normal status on day 28. SP-A, B, and AQP-1 mRNA expression in BLM-stimulated group were significantly lower than those in the control group (P<0.001).

CONCLUSIONBLM-injured AT-II cells decrease the levels of SP-A, B, and AQP-1 mRNA and cause PS dysfunction, resulting in hypoxemia and pneumonedema.

Animals ; Aquaporin 1 ; biosynthesis ; genetics ; Bleomycin ; administration & dosage ; toxicity ; Cells, Cultured ; Dose-Response Relationship, Drug ; Epithelial Cells ; drug effects ; metabolism ; Hypoxia ; chemically induced ; metabolism ; pathology ; Male ; Pulmonary Alveoli ; cytology ; drug effects ; Pulmonary Surfactant-Associated Protein A ; biosynthesis ; genetics ; Pulmonary Surfactant-Associated Protein B ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Time Factors

BACKGROUNDThe decrease of surfactant protein (SP) secreted by the alveolar type II cell is one of the important causes of limiting air of pulmonary emphysema. However, the SP-A gene and protein changes in this disease are rarely studied. This study was undertaken to investigate alterations in SP-A gene activity and protein, and to explore their roles in the pathogenesis of emphysematous changes.

METHODSTwenty Wistar rats were divided randomly into a normal control group (n = 10) and a cigarette smoking (CS) + lipopolysaccharide (LPS) group (n = 10). Ultra-structural changes were observed under an electron microscope. The number of cells positive for SP-A was measured by immunohistochemistry. The mRNA expression and protein level of SP-A in the lung tissues were determined by quantitative polymerase chain reaction (qPCR) and Western blot separately. The protein level of SP-A in lavage fluid was determined by Western blot.

RESULTSThe number of cells positive for SP-A of the CS + LPS group (0.35 +/- 0.03) was lower than that of the blank control group (0.72 +/- 0.06, P < 0.05). The level of SP-A in the lung tissues of rats in the CS + LPS group (0.2765 +/- 0.0890) was lower than that in the blank control group (0.6875 +/- 0.1578, P < 0.05). The level of SP-A in the lavage fluid of rats in the CS + LPS group (0.8567 +/- 0.1458) was lower than that in the blank control group (1.3541 +/- 0.2475, P < 0.05). The lung tissues of rats in the CS + LPS group showed an approximate increase (0.4-fold) in SP-A mRNA levels relative to beta-actin mRNA (P < 0.05).

CONCLUSIONSThe changes of SP-A may be related to emphysematous changes in the lung. And cigarette smoke and LPS alter lung SP-A gene activity and protein homeostasis.

Animals ; Blotting, Western ; Emphysema ; metabolism ; pathology ; Homeostasis ; Immunohistochemistry ; Male ; Microscopy, Electron ; Polymerase Chain Reaction ; Pulmonary Surfactant-Associated Protein A ; analysis ; genetics ; RNA, Messenger ; analysis ; Rats ; Rats, Wistar

OBJECTIVETo investigate the changes in the pulmonary surface tension and the tissue content of surfactant substance protein B (SP-B) in rabbits during early post-injury stage after smoke inhalation injury.

METHODSThirty-two healthy rabbits inflicted with smoke inhalation injury were employed in the study as injury group, and they were sacrificed at 0.5, 2.0, 6.0, 12.0 post injury hours (PIH), with 8 rabbits at each time point. Another 8 rabbits were assigned to normal control group. The pulmonary tissue samples of the rabbits in each group were harvested for the collection of bronchial-alveolar lavage fluid (BALF). The changes in maximal tension (Tmax), minimal tension (Tmin) and hysteresis square (HS) of BALF were measured after the addition of 0.5, 1.0 and 3.0 ml of SP-B antibody into the BALF of the rabbits in each group. The changes in SP-B and SP-B mRNA contents in rabbit pulmonary tissue of each group were assessed with immunohistochemistry and in situ hybridization techniques, respectively.

RESULTSThere was no obvious difference in Tmax in BALF of each group or at each time point before and after the action of different concentrations of SP-B antibody in BALF (P > 0.05). But the Tmin in injury group at 2, 6 and 12 PIH was much higher than that before the addition of the antibody (P < 0.05). And the change in HS was similar to that in Tmin. The SP-B content in alveolar type II epithelial cells (AT-II) was decreased significantly at 2, 6 and 12 PIH, whereas the expression in SP-B mRNA exhibited no change.

CONCLUSIONThere was no obvious change in SP-B synthesis by AT-II in the lung tissue of the rabbits inflicted with smoke inhalation injury during early post injury stage. The increase of SP-B secretion from AT-II cells might be beneficial to the early protection of pulmonary tissue of the rabbits with smoke inhalation injury.

Animals ; Female ; Immunohistochemistry ; Lung ; chemistry ; Male ; Pulmonary Surfactant-Associated Protein B ; analysis ; genetics ; RNA, Messenger ; analysis ; Rabbits ; Smoke Inhalation Injury ; metabolism ; Surface Tension

Silicosis is one of the most serious occupational diseases in China and dates back to centuries ago. In this study, we successfully established a rat model of silicosis by intratracheal silica injection for 28 days and determined hydroxyproline levels to evaluate collagen metabolism in lung homogenates. Oxidative stress status was evaluated by detecting catalase and glutathione peroxidase activities. Expression levels of peroxiredoxins (Prx I and Prx VI) were detected by Western blotting. Pulmonary surfactant protein A (SP-A) levels in rat serum and lung tissue were analyzed by ELISA, and SP-A and Prx expression levels in lung tissues were detected by immunohistochemistry. The results suggest that Prx proteins may be involved in pulmonary fibrosis induced by silica. Downregulation of SP-A expression caused due to silica is an important factor in the occurrence and development of silicosis.
Animals ; Disease Models, Animal ; Humans ; Lung ; enzymology ; metabolism ; Male ; Oxidative Stress ; Peroxiredoxin VI ; genetics ; metabolism ; Peroxiredoxins ; genetics ; metabolism ; Pulmonary Surfactant-Associated Protein A ; genetics ; metabolism ; Rats ; Silicon Dioxide ; toxicity ; Silicosis ; genetics ; metabolism