Characterization of air-liquid interface culture of A549 alveolar epithelial cells

Alveolar epithelia play an essential role in maintaining the integrity and homeostasis of lungs, in which alveolar epithelial type II cells (AECII) are a cell type with stem cell potential for epithelial injury repair and regeneration. However, mechanisms behind the physiological and pathological roles of alveolar epithelia in human lungs remain largely unknown, partially owing to the difficulty of isolation and culture of primary human AECII cells. In the present study, we aimed to characterize alveolar epithelia generated from A549 lung adenocarcinoma cells that were cultured in an air-liquid interface (ALI) state. Morphological analysis demonstrated that A549 cells could reconstitute epithelial layers in ALI cultures as evaluated by histochemistry staining and electronic microscopy. Immunofluorescent staining further revealed an expression of alveolar epithelial type I cell (AECI) markers aquaporin-5 protein (AQP-5), and AECII cell marker surfactant protein C (SPC) in subpopulations of ALI cultured cells. Importantly, molecular analysis further revealed the expression of AQP-5, SPC, thyroid transcription factor-1, zonula occludens-1 and Mucin 5B in A549 ALI cultures as determined by both immunoblotting and quantitative RT-PCR assay. These results suggest that the ALI culture of A549 cells can partially mimic the property of alveolar epithelia, which may be a feasible and alternative model for investigating roles and mechanisms of alveolar epithelia in vitro.

Pulmonary surfactant homeostasis associated genetic abnormalities and lung diseases / 中华医学遗传学杂志

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.

Development of a Synthetic Surfactant Using a Surfactant Protein-C Peptide Analog: In Vitro Studies of Surface Physical Properties

PURPOSE: Pulmonary surfactant (PS) replacement has been the gold standard therapy for neonatal respiratory distress syndrome; however, almost all commercial PSs contain animal proteins. We prepared a synthetic PS by using a human surfactant protein (SP) analog and evaluated its in vitro properties. MATERIALS AND METHODS: A peptide sequence (CPVHLKRLLLLLLLLLLLLLLLL) of human SP-C was chosen to develop the peptide analog (SPa-C). The new synthetic SP-C PS (sSP-C PS) was synthesized from SPa-C, dipalmitoyl phosphatidylcholine, phosphatidyl glycerol, and palmitic acid. Physical properties of the sSP-C PS were evaluated by measuring the maximum and minimum surface tensions (STs), surfactant spreading, and adsorption rate. In addition, we recorded an ST-area diagram. The data obtained on sSP-C PS were subsequently compared with those of purified natural bovine surfactant (PNBS), and the commercial product, Surfacten(R). RESULTS: The sSP-C PS and Surfacten(R) were found to have maximum ST values of 32-33 mN/m, whereas that of PNBS was much lower at 19 mN/m. The minimum ST values of all three products were less than 10 mN/m. The values that were measured for the equilibrium ST of rapidly spreading sSP-C PS, Surfacten(R), and PNBS were 27, 27, and 24 mN/m, respectively. The surface adsorptions were found to be the same for all three PSs (20 mN/m). ST-area diagrams of sSP-C PS and Surfacten(R) revealed similar properties. CONCLUSION: In an in vitro experiment, the physical properties exhibited by sSP-C PS were similar to those of Surfacten(R). Further study is required to evaluate the in vivo efficacy.

I73T mutation in the pulmonary surfactant protein C gene associated with pediatric interstitial lung disease: a case study and the review of related literature / 中华儿科杂志

<p><b>OBJECTIVE</b>To report a case of I73T mutation in the pulmonary surfactant protein (SP)-C gene associated with pediatric interstitial lung disease, and study the clinical diagnosis and review related literature, to investigate the role of gene detection in the diagnosis of interstitial lung disease in infants and children.</p><p><b>METHOD</b>The clinical, radiological, and genetic testing information of the case was analyzed and related literature was reviewed.</p><p><b>RESULT</b>(1) An 8-month-old girl was hospitalized because of cough, tachypnea, continuous oxygen therapy and failure to thrive. Physical examination on admission revealed tachypnea, slight cyanosis and the three concave sign was positive, respiratory rate of 50 times/minute, scattered fine crackles could be heard over both lungs, clubbing fingers were found. No other abnormalities were noted. Laboratory test results: pathogenic examination was negative, multiple blood gas analysis suggested hypoxemia. Chest CT showed ground-glass like opacity, diffused tubercle infiltration. The I73T mutation in SP-C gene was identified by SP-related gene sequencing. (2) The review of related literature: Data of 3 infants with I73T mutation in SP-C gene showed that all the 3 cases had tachypnea and dyspnea, chest CT revealed diffuse infiltration or diffuse ground glass pattern in lungs, the major pathology of lungs was nonspecific interstitial pneumonia (NSIP).</p><p><b>CONCLUSION</b>A case of interstitial lung disease with I73T mutation in SP-C gene was preliminarily diagnosed in an infant. Gene test provides an important tool in the diagnosis of such pediatric interstitial lung disease.</p>

Pulmonary surfactant protein gene mutation associated with pediatric interstitial lung disease: a case study and the review of related literature / 中华儿科杂志

<p><b>OBJECTIVE</b>To report a case of pulmonary surfactant protein (SP) gene mutation associated with pediatric interstitial lung disease, and study the clinical diagnosis process and review of related literature, to understand the relationship between interstitial lung disease and SP gene mutation in infants and children.</p><p><b>METHOD</b>The clinical, radiological, histological, and genetic testing information of a case of SP gene mutation related pediatric interstitial lung disease were analyzed and related literature was reviewed.</p><p><b>RESULT</b>A 2-year-old girl without a history of serious illness was hospitalized because of the shortness of breath, cough, excessive sputum, and the progressive dyspnea. Physical examination on admission revealed tachypnea, slight cyanosis, and the retraction signs were positive, respiratory rate of 60 times/minute, fine crackles could be heard through the lower lobe of both lungs; heart rate was 132 beats/minute. No other abnormalities were noted, no clubbing was found. Laboratory test results: pathologic examination was negative, multiple blood gas analysis suggested hypoxemia. Chest CT showed ground-glass like opacity, diffused patchy infiltration. Bronchoalveolar lavage fluid had a large number of neutrophils, and a few tissue cells. Eosinophil staining: negative. Fluconazole and methylprednisolone were given after admission, pulmonary symptoms and signs did not improve, reexamination showed no change in chest CT. Then lung biopsy was carried out through thoracoscopy. Histopathology suggested chronic interstitial pneumonia with fibrosis. The heterozygous mutation of R219W in the SFPTA1 and the S186N in SFTPC were identified by SP-related gene sequencing. The review of related literature showed that polymorphisms at the 219th amino acid in SP-A1 allele were found in adults with idiopathic pulmonary fibrosis (IPF), but there is no related literature in pediatric cases. The patient in this report had a mutation at the SP-A1 allele consistent with related literature. Data of 17 young children with mutation in SP-C gene showed that all the 17 cases had dyspnea and tachypnea, chest CT revealed diffuse opacities in lungs, the pathology of lungs was NSIP and CPI. There were 17 kinds of mutation and the common mutation was I73T. The mutation of S186N in SFTPC in our case has never been shown in previously published literature.</p><p><b>CONCLUSION</b>A case of interstitial lung disease with S186N gene mutation in SFTPC was preliminarily diagnosed in an infant. The SP-C gene mutations and polymorphisms are associated with pediatric interstitial lung disease.</p>

Pulmonary surfactant associated gene variants in mixed ethnic population of Han and Zhuang / 中华儿科杂志

<p><b>OBJECTIVE</b>To explore the prevalence of pulmonary surfactant associated pathway genes functional variants in Chinese population.</p><p><b>METHOD</b>Using a cohort of 258 mixed ethnic population of Han and Zhuang, we pooled DNA samples from 146 term male infants and 112 term female infants and then used an Ill umina next generation sequencing platform to perform the complete exonic resequencing in 6 target genes:surfactant protein-B (SFTPB), surfactant protein-C (SFTPC), ATP-binding cassette transporter A3 (ABCA3), lysophospholipid acyltransferase 1 (LPCAT1), choline phosphotransferase 1 (CHPT1), phosphate cytidylyltransferase 1, choline, beta (PCYT1B). Collapsing methods was used to determine the functional allele frequency.</p><p><b>RESULT</b>(1) Altogether, 128 variants were found, including 44 synonymous variants, 66 nonsynonymous variants and 18 insertions-deletions. Of these, 28 variants were predicted to alter protein function. Two of these variants were seen twice, the rest variants were only seen once, for a total of 30 functional alleles; (2) ABCA3 had the most functional variants in both male and female groups with the minor allele frequencies of 0.014 (1.4%) and 0.04 (4%), respectively. The total functional allele frequencies of 6 genes were 0.041 (4.1%) and 0.08 (8%) in the two groups, respectively (P = 0.06).</p><p><b>CONCLUSION</b>(1) Functional variants in pulmonary surfactant associated pathway genes are present in the mixed Han-Zhuang population. (2) ABCA3 contained the most functional variants suggesting that ABCA3 could contribute significantly to neonatal respiratory distress syndrome and other lung disease.</p>

Evaluation and management of inherited disorders of surfactant metabolism / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To 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).</p><p><b>DATA SOURCES</b>Review of the literature, previous work from the author's and collaborators' laboratories, St. Louis Children's Hospital Lung Transplant Database.</p><p><b>STUDY SELECTION</b>Key articles in the field, author's work.</p><p><b>RESULTS</b>Inherited 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,</p><p><b>CONCLUSIONS</b>Inherited disorders of surfactant metabolism are rare, but informative diseases that provide unique opportunities for understanding mechanisms of respiratory disease in newborns and children.</p>

Expression of HoxB5, SPC and AQP5 in neonatal rats with hyperoxia-induced chronic lung disease / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Alveolar epithelium impairment is one of pathological changes associated with chronic lung disease (CLD). Hoxb5 is one of the few homeobox genes strongly expressed in the developing lung. This study investigated the expression of HoxB5, SPC and AQP5 in rats with CLD in order to explore the role of Hoxb-5 in impairment and reparation of alveolar epithelium.</p><p><b>METHODS</b>Eighty neonatal rats were randomly exposed to hyperoxia (model group) or to room air (control group) (n=40 each). The CLD model was induced by hyperoxia exposure. The expression of HoxB5, SPC and AQP5 protein and mRNA in the lung tissue was detected by immunohistochemistry and RT-PCR 1, 3, 7, 14 and 21 days after exposure.</p><p><b>RESULTS</b>In the model group HoxB5 expression significantly decreased 7, 14 and 21 days after hyperoxia exposure. SPC expression decreased 3 days after hyperoxia exposure but increased significantly 7, 14 and 21 days after hyperoxia exposure as compared to the control group. AQP5 expression was progressively reduced with prolonged hyperoxia exposure.</p><p><b>CONCLUSIONS</b>Hyperoxia exposure may lead to alveolar epithelial cell (AEC) damage in neonatal rats. The increased SPC expression and decreased AQP5 expression suggested that the ability of differentiation and transformation of AECII into AECI decreased in neonatal rats with CLD. The decreased HoxB5 expression following hyperoxia exposure might contribute to a decreased ability of differentiation of AECII.</p>

Lung adenocarcinoma stem cell phenotypes and their correlation with patient prognosis / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To detect the cancer stem cells and to evaluate their prognostic implication in patients with lung adenocarcinoma.</p><p><b>METHODS</b>Three phenotypic markers of cancer stem cells (SP-C, CCSP and OCT4) in lung adenocarcinoma were detected by immunofluorecence staining. The correlation among the clinicopathological parameters and phenotypes of cancer stem cells as well as survival were analyzed by Cox proportional hazard method.</p><p><b>RESULTS</b>Of the 57 cases, cancer stem cells were detected in 52, including OCT4(+) bronchioloalveolar stem cell (BASC) phenotype (SP-C(+) CCSP(+) OCT4(+)) in 40 cases and OCT4(-) BASC phenotype (SP-C(+) CCSP(+) OCT4(-)) in 12 cases. Statistical analysis revealed that the phenotype of cancer stem cells was related with the cellular differentiation, i.e. the OCT4(+) BASC phenotype occurred more frequently in the well-differentiated tumors, while the OCT4(-) BASC phenotype usually presented in most of the poorly-differentiated ones. Cox analysis showed that the OCT4(+) BASC phenotype was one of prognostic factors.</p><p><b>CONCLUSION</b>The lung adenocarcinoma stem cells have phenotypic features of bronchioalveolar stem cells (SP-C(+) CCSP(+)). The expression of self-renewal regulatory gene OCT4 in these cells indicates an aggressive nature and unfavorable prognosis.</p>

The importance of surfactant on the development of neonatal pulmonary diseases

Pulmonary surfactant is a substance composed of a lipoprotein complex that is essential to pulmonary function. Pulmonary surfactant proteins play an important role in the structure, function, and metabolism of surfactant; 4 specific surfactant proteins have been identified: surfactant proteins-A, surfactant proteins-B, surfactant proteins-C, and surfactant proteins-D. Clinical, epidemiological, and biochemical evidence suggests that the etiology of respiratory distress syndrome is multifactorial with a significant genetic component. There are reports about polymorphisms and mutations on the surfactant protein genes, especially surfactant proteins-B, that may be associated with respiratory distress syndrome, acute respiratory distress syndrome, and congenital alveolar proteinosis. Individual differences regarding respiratory distress syndrome and acute respiratory distress syndrome as well as patient response to therapy might reflect phenotypic diversity due to genetic variation, in part. The study of the differences between the allelic variants of the surfactant protein genes can contribute to the understanding of individual susceptibility to the development of several pulmonary diseases. The identification of the polymorphisms and mutations that are indeed important for the pathogenesis of the diseases related to surfactant protein dysfunction, leading to the possibility of genotyping individuals at increased risk, constitutes a new research field. In the future, findings in these endeavors may enable more effective genetic counseling as well as the development of prophylactic and therapeutic strategies that would provide a real impact on the management of newborns with respiratory distress syndrome and other pulmonary diseases.

O surfactante pulmonar é uma substância composta por um complexo lipoprotéico essencial para a função pulmonar normal. As proteínas do surfactante têm importante papel na estrutura, função e metabolismo do surfactante. São descritas quatro proteínas específicas denominadas surfactante pulmonar-A, surfactante pulmonar-B, surfactante pulmonar-C e surfactante pulmonar-D. Evidências clínicas, epidemiológicas e bioquímicas sugerem que a etiologia da síndrome do desconforto respiratório é multifatorial com um componente genético significativo. Existem na literatura algumas descrições sobre a presença de polimorfismos e mutações em genes dos componentes do surfactante, particularmente no gene da surfactante pulmonar-B, os quais parecem estar associados à síndrome do desconforto respiratório, síndrome da angustia respiratória aguda e proteinose alveolar congênita. Diferenças individuais relacionadas à síndrome do desconforto respiratórioe síndrome da angustia respiratória aguda e à resposta dos pacientes ao tratamento podem refletir diversidade fenotípica, devido, parcialmente, à variação genética. O estudo das diferenças entre as variantes alélicas dos genes das proteínas do surfactante pode ajudar na compreensão das variabilidades individuais na susceptibilidade ao desenvolvimento de várias doenças pulmonares. A determinação de quais polimorfismos e mutações são, de fato, importantes na patogênese das doenças relacionadas à disfunção das proteínas do surfactante e a possibilidade da realização da genotipagem em indivíduos de alto risco constitui um novo campo de pesquisa, que pode permitir, futuramente, um aconselhamento genético mais efetivo, resultando no desenvolvimento de estratégias profiláticas e terapêuticas que representem um impacto real no manejo dos recém-nascidos portadores da síndrome do desconforto respiratório e outras patologias pulmonares.

Development and developmental disorders of the respiratory system

Congenital anomalies of the respiratory system contribute significantly to respiratory stridor and other complications in neonates. They are often associated with abnormalities of other organ systems. The nasal placode deepens to form the nasal sac from which the nasal and olfactory mucosae develop. Paranasal air sinuses develop as extensions of the nasal cavity into the adjacent bony structures. Choanal atresia is probably a result of persistent oronasal membrane. The laryngotracheal primordium grows out from the ventral aspect of the pharyngeal portion of the foregut during week 4 of embryonic life. The larynx and trachea represent the proximal portions of this endodermal outgrowth. The lung buds arise from the tip of this outgrowth. The laryngeal cartilages and muscles develop from the 4th and 6th pharyngeal arches. Posterior laryngeal clefts might involve the interarytenoid fold, cricoid lamina or the posterior wall of the entire larynx and trachea. Laryngomalacia resulting from abnormal development of laryngeal cartilages causes respiratory stridor in pediatric patients. Laryngeal webs, stenosis and atresia are possibly recanalization defects and are the anatomical basis of congenital high airway obstruction syndrome. Defective neural crest development appears to be the common denominator between obstructive lesions of the upper airway and several craniofacial malformations. The lung bud branches dichotomously and constitutes the bronchial tree. There is a morphogenetic tissue interaction between the endodermal epithelium and the surrounding mesenchyme during lung development. Branching morphogenesis appears to be guided by FGF, SHH, BMP-4, and Gli2, Gli 3 signaling. SFTPB, SFTPC and ABCA3 genes have been found to control surfactant production. Molecular and cellular bases of the development and developmental control mechanisms of the respiratory tract are only beginning to be understood

Genética molecular del surfactante pulmonar / Molecular genetics in pulmonary surfactant

Se revisan los estudios que han sido publicados recientemente acerca de las características estructurales de las proteínas constituyentes del surfactante pulmonar natural y los genes que las codifican, así como las variaciones polimórficas en ellos y su asociación con patologías pulmonares que se caracterizan por déficit del surfactante pulmonar

Comparison of the effect of ambroxol and dexamethasone on the expression of pulmonary surfactant proteins in the fetal rat lungs / 中华儿科杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>A 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).</p><p><b>RESULTS</b>(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).</p><p><b>CONCLUSION</b>Antepartum administration of both ambroxol and dexamethasone can significantly increase fetal lung SP-A, SP-B and SP-C mRNAs expression.</p>

Effect of Dexamethasone on Gene Expression of Surfactant Protein B and Surfactant Protein C / 결핵

BACKGROUND: Surfactant protein B(SP-B) and surfactant protein C(SP-C) are important in accelerating surface spreading of surfactant phospholipid. The glucocorticoids accelerate the morphologic differentiation of epithelial cells into type II cells and increase the rate of phosphatidylcholine synthesis. The hydrophobic surfactant protein has been shown to be upregulated by glucocorticoids in vitro, however, its regulation in vivo is not well established. METHODS: The authors investigated the effects of glucocorticoid on the accumulation of mRNA encoding SP-B and SP-C protein content of the lung. Adult rats were given different doses of subcutaneous dexamethasone and sacrificed at 24 hours and 1 week. SP-B and SP-C mRNA were measured by a filter hybridization method. RESULTS: 1) The accumulation of SP-B mRNA at 24 hours after 0.2 mg/kg dexamethasone treatment was increased by 23.7%. 2) The accumulation of SP-B mRNA at 1 week after 2 mg/kg dexamethasone treatment was significantly increased by 96.6%(P<0.001). 3) The accumulation of SP-C mRNA at 24 hours after 0.2 mg/kg dexamethasone treatment was significantly increased by 42.7%(P<0.01). 4) The accumulation of SP-C mRNA at 1 week after 2 mg/kg dexamethasone treatment was significantly increased by 60.0% (P<0.01). CONCLUSION: The authors concluded that dexamethasone treatment in vivo resulted in increased levels of SP-B mRNA and SP-C mRNA. These results suggested that dexamethasone stimulates the synthesis of hydrophobic proteins associated with surfactant.