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Biomedical subjects

S E Wert

Publications and source records attributed to S E Wert.

At least 19 recordsLinked to original sources
PubMed2005

Stage-specific regulation of respiratory epithelial cell differentiation by Foxa1.

Foxa1 is a member of the winged helix family of transcription factors that is expressed in epithelial cells of the conducting airways and in alveolar type II cells of the lung. To determine the role of Foxa1 during lung morphogenesis, histology and gene expression were assessed in lungs from Foxa1-/- gene-targeted mice from embryonic day (E) 16.5 to postnatal day (PN) 13. Deletion of Foxa1 perturbed maturation of the respiratory epithelium at precise times during lung morphogenesis. While dilatation of peripheral lung saccules was delayed in Foxa1-/- mice at E16.5, sacculation was unperturbed later in development (E17.5-E18.5). At PN5, alveolarization was markedly delayed in Foxa1-/- mice; however, by PN13 lung histology was comparable to wild-type controls. Clara cell secretory protein (CCSP), prosurfactant protein (SP)-C, and SP-B protein content and immunostaining were decreased in Foxa1-/- mice between E16.5 and E18.5 but normalized after birth. Timing and sites of expression of thyroid transcription factor-1, Foxj1, and beta-tubulin were unaltered in lungs of Foxa1-/- mice. In vitro, Foxa1 regulated the activity of CCSP and SP-A, SP-B, SP-C, and SP-D promoters as assessed by luciferase reporter assays in HeLa, H441, and MLE15 cells. Although Foxa1 regulates respiratory epithelial differentiation and structural maturation of the lung at precise developmental periods, the delay in maturation is subsequently compensated at times to enable respiratory function and restore normal lung structure after birth.

Animals↗
PubMed2001

Aquaporin 5-deficient mouse lungs are hyperresponsive to cholinergic stimulation.

Although aquaporin 5 (AQP5) is the major water channel expressed in alveolar type I cells in the lung, its actual role in the lung is a matter of considerable speculation. By using immunohistochemical staining, we show that AQP5 expression in mouse lung is not restricted to type I cells, but is also detected in alveolar type II cells, and in tracheal and bronchial epithelium. Aqp5 knockout (Aqp5(-/-)) mice were used to analyze AQP5 function in pulmonary physiology. Compared with Aqp5(+/+) mice, Aqp5(-/-) mice show a significantly increased concentration-dependent bronchoconstriction to intravenously administered Ach, as shown by an increase in total lung resistance and a decrease in dynamic lung compliance (P < 0.05). Likewise, Penh, a measure of bronchoconstriction, was significantly enhanced in Aqp5(-/-) mice challenged with aerosolized methacholine (P < 0.05). The hyperreactivity to bronchoconstriction observed in the Aqp5(-/-) mice was not due to differences in tracheal smooth muscle contractility in isolated preparations or to altered levels of surfactant protein B. These data suggest a novel pathway by which AQP5 influences bronchoconstriction. This observation is of special interest because studies to identify genetic loci involved in airway hyperresponsiveness associated with asthma bracket genetic intervals on human chromosome 12q and mouse chromosome 15, which contain the Aqp5 gene.

Acetylcholine↗
PubMed2001

Surfactant proteins and cell markers in the respiratory epithelium of the amphibian, Ambystoma mexicanum.

The respiratory tract is lined by diverse epithelial cell types whose morphology, gene expression and functions are highly specialized along the cephalo-caudal axis of the lung. Pulmonary gas exchange, surface tension reduction, host defense, fluid and electrolyte transport are functions shared by various vertebrate species, each organism facing similar requirements for adaptation to air breathing. Consistent with this concept, we have identified distinct respiratory epithelial cell populations in the amphibian, Ambystoma mexicanum, using morphologic, histochemical and immunochemical techniques. Thyroid transcription factor-1 (TTF-1), a homeodomain nuclear transcription factor critical to lung formation, and surfactant protein B (SP-B), an amphipathic polypeptide required for surfactant function, were detected in the peripheral respiratory epithelial cells of the axolotl lung, in cells with characteristics of Type II alveolar epithelial cells in mammals. beta-Tubulin and carbohydrate staining identified distinct subsets of ciliated and goblet cells. SP-D, a member of the collectin family of innate host defense proteins, was also detected in peripheral epithelial cells of the axolotl lung. Pulmonary surfactant and host defense proteins are shared across diverse phyla supporting the concept that pulmonary structure and function have evolved from common ancestors.

Ambystoma mexicanum↗
PubMed2001

Surfactant protein deficiency in familial interstitial lung disease.

OBJECTIVE: To determine the contribution of surfactant protein abnormalities to the development of chronic lung injury in a familial form of interstitial lung disease. STUDY DESIGN: An 11-year-old girl, her sister, and their mother who were diagnosed with chronic interstitial lung disease underwent laboratory investigation of surfactant protein expression in bronchoalveolar lavage fluid and lung biopsy specimens. Nineteen patients with idiopathic pulmonary fibrosis and 9 patients who were investigated for pulmonary malignancy but who did not have interstitial lung disease served as control subjects. RESULTS: The 3 family members were found to have absent surfactant protein C (SP-C) and decreased levels of SP-A and SP-B in bronchoalveolar lavage fluid (BALF). Immunostaining for pulmonary surfactant proteins in lung biopsy specimens obtained from both children demonstrated a marked decrease of pro-SP-C in the alveolar epithelial cells but strong staining for pro-SP-B, SP-B, SP-A, and SP-D. No deviations from published surfactant protein B or C coding sequences were identified by DNA sequence analysis. All control subjects had a detectable level of SP-C in the BALF. CONCLUSION: The apparent absence of SP-C and a decrease in the levels of SP-A and SP-B are associated with familial interstitial lung disease.

Adult↗
PubMed2001

FGF-10 disrupts lung morphogenesis and causes pulmonary adenomas in vivo.

Transgenic mice in which fibroblast growth factor (FGF)-10 was expressed in the lungs of fetal and postnatal mice were generated with a doxycycline-inducible system controlled by surfactant protein (SP) C or Clara cell secretory protein (CCSP) promoter elements. Expression of FGF-10 mRNA in the fetal lung caused adenomatous malformations, perturbed branching morphogenesis, and caused respiratory failure at birth. When expressed after birth, FGF-10 caused multifocal pulmonary tumors. FGF-10-induced tumors were highly differentiated papillary and lepidic pulmonary adenomas. Epithelial cells lining the tumors stained intensely for thyroid transcription factor (TTF)-1 and SP-C but not CCSP, indicating that FGF-10 enhanced differentiation of cells to a peripheral alveolar type II cell phenotype. Withdrawal from doxycycline caused rapid regression of the tumors associated with rapid loss of the differentiation markers TTF-1, SP-B, and proSP-C. FGF-10 disrupted lung morphogenesis and induced multifocal pulmonary tumors in vivo and caused reversible type II cell differentiation of the respiratory epithelium.

Adenoma↗
PubMed2001

SP-D and GM-CSF regulate surfactant homeostasis via distinct mechanisms.

Both surfactant protein (SP) D and granulocyte-macrophage colony-stimulating factor (GM-CSF) influence pulmonary surfactant homeostasis, with the deficiency of either protein causing marked accumulation of surfactant phospholipids in lung tissues and in the alveoli. To assess whether the effects of each gene were mediated by distinct or shared mechanisms, surfactant homeostasis and lung morphology were assessed in 1) double-transgenic mice in which both SP-D and GM-CSF genes were ablated [SP-D(-/-),GM(-/-)] and 2) transgenic mice deficient in both SP-D and GM-CSF in which the expression of GM-CSF was increased in the lung. Saturated phosphatidylcholine (Sat PC) pool sizes were markedly increased in SP-D(-/-),GM(-/-) mice, with the effects of each gene deletion on surfactant Sat PC pool sizes being approximately additive. Expression of GM-CSF in lungs of SP-D(-/-),GM(-/-) mice corrected GM-CSF-dependent abnormalities in surfactant catabolism but did not correct lung pathology characteristic of SP-D deletion. In contrast to findings in GM(-/-) mice, degradation of [(3)H]dipalmitoylphosphatidylcholine by alveolar macrophages from the SP-D(-/-) mice was normal. The emphysema and foamy macrophage infiltrates characteristic of SP-D(-/-) mice were similar in the presence or absence of GM-CSF. Taken together, these findings demonstrate the distinct roles of SP-D and GM-CSF in the regulation of surfactant homeostasis and lung structure.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

Immunolocalization of sonic hedgehog (Shh) in developing mouse lung.

Expression of sonic hedgehog (Shh) is required for normal development of the lung during embryogenesis. Loss of Shh expression in mice results in tracheoesophageal fistula, lung hypoplasia, and abnormal lung lobulation. To determine whether Shh may play a role later in lung morphogenesis, immunostaining for Shh was performed in mouse lung from embryonic day (E) 10.5 to postnatal day (PD) 24. Shh was detected in the distal epithelium of the developing mouse lung from E10.5 to E16.5. From E16.5 until PD15, Shh was present in epithelial cells in both the peripheral and conducting airways. Although all cells of the developing epithelium uniformly expressed Shh at E10.5, Shh expression was restricted to subsets of epithelial cells by E16.5. Between E16.5 and PD15, non-uniform Shh staining of epithelial cells was observed in the conducting airways in a pattern consistent with the distribution of non-ciliated bronchiolar cells (i.e., Clara cells) and the Clara cell marker CCSP. Shh did not co-localize with hepatocyte nuclear factor/forkhead homologue-4 (HFH-4), beta-tubulin, or with the presence of cilia. These results support the concept that Shh plays a distinct regulatory role in the lung later in morphogenesis, when it may influence formation or cytodifferentiation of the conducting airways.

Animals↗
PubMed2000

Role of cystic fibrosis transmembrane conductance regulator in pulmonary clearance of Pseudomonas aeruginosa in vivo.

Cystic fibrosis (CF)2 is a fatal genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) that is commonly associated with chronic pulmonary infections with mucoid Pseudomonas aeruginosa (PA). To test the hypothesis that CFTR plays a direct role in PA adhesion and clearance, we have used mouse lines expressing varying levels of human (h) or mouse (m) CFTR. A subacute intratracheal dose of 3 x 10(6) bacteria was cleared with similar kinetics in control wild-type (WT) and transgenic mice overexpressing hCFTR in the lung from the surfactant protein C (SP-C) promoter (SP-C-hCFTR+/-). In a second series of experiments, the clearance of an acute intratracheal dose of 1.5 x 10(7) PA bacteria was also similar in WT, hemizygous SP-C-hCFTR+/-, and bitransgenic gut-corrected FABP-hCFTR+/+-mCFTR-/-, the latter lacking expression of mCFTR in the lung. However, a small but significant decrease in bacterial killing was observed in lungs of homozygote SP-C-hCFTR+/+ mice. Lung pathology in both WT and SP-C-hCFTR+/+ mice was marked by neutrophilic inflammation and bacterial invasion of perivascular and subepithelial compartments. Bacteria were associated primarily with leukocytes and were not associated with alveolar type II or bronchiolar epithelial cells, the cellular sites of SP-C-hCFTR+/+ transgene expression. The results indicate that there is no direct correlation between levels of CFTR expression and bacterial clearance or association of bacteria with epithelial cells in vivo.

Animals↗
PubMed2000

Increased metalloproteinase activity, oxidant production, and emphysema in surfactant protein D gene-inactivated mice.

Targeted ablation of the surfactant protein D (SP-D) gene caused chronic inflammation, emphysema, and fibrosis in the lungs of SP-D (-/-) mice. Although lung morphology was unperturbed during the first 2 weeks of life, airspace enlargement was observed by 3 weeks and progressed with advancing age. Inflammation consisted of hypertrophic alveolar macrophages and peribronchiolar-perivascular monocytic infiltrates. These abnormalities were associated with increased activity of the matrix metalloproteinases, MMP2 and MMP9, and immunostaining for MMP9 and MMP12 in alveolar macrophages. Hydrogen peroxide production by isolated alveolar macrophages also was increased significantly (10-fold). SP-D plays a critical role in the suppression of alveolar macrophage activation, which may contribute to the pathogenesis of chronic inflammation and emphysema.

Animals↗
PubMed2000

Recurrent familial neonatal deaths: hereditary surfactant protein B deficiency.

Hereditary surfactant protein B (SP-B) deficiency is an uncommon autosomal recessive lung disorder that causes hypoxemic respiratory failure in mature, morphologically normal infants. Recognition and diagnosis of this condition is of paramount importance, as it has significant implications for future pregnancies with a recurrence risk of 25%. In a family with three neonatal deaths over 20 years, SP-B deficiency was diagnosed following the death of the fourth affected infant. Previous deaths were mistakenly attributed to hyaline membrane disease (HMD), congenital Mycoplasma hominis infection, and pulmonary hypertension, however, following the diagnosis in the proposita, SP-B deficiency was also confirmed in her deceased siblings by immunohistochemical staining of autopsy specimens. This case highlights the presentation, postnatal course, diagnosis, and therapeutic options of SP-B deficiency in addition to the mode of inheritance and the possibility of antenatal diagnosis. Genetic consultation is imperative in the investigations of recurrent neonatal deaths, especially in cases of remote events. The recent enormous advances in human genetics have shown that many conditions previously ascribed to environmental agents have a genetic basis.

Fatal Outcome↗
PubMed2000

Deficiency of lamellar bodies in alveolar type II cells associated with fatal respiratory disease in a full-term infant.

We report a case of a full-term female infant who presented with severe respiratory distress shortly after birth and died at 23 d of age with unremitting respiratory failure. Infectious and other known causes of respiratory disease in this clinical setting were excluded. Examination of a lung biopsy showed abnormal lung parenchyma with features reminiscent of desquamative interstitial pneumonitis. Ultrastructural studies revealed that alveolar type II cells lacked cytoplasmic lamellar bodies, while other organelles appeared normal. Histochemical and immunohistochemical investigations indicated normal alveolar type II cell marker expression including surfactant proteins (SP-A, SP-B, pro-SP-B, and pro-SP-C). Mutations in the coding sequences of the SP-B gene were excluded as a cause of disease. This case appears to be a novel congenital defect affecting the pulmonary surfactant system. The cellular abnormality may involve the assembly of cytoplasmic lamellar bodies in alveolar type II cells-the principal storage site of pulmonary surfactant.

Biopsy↗
PubMed2000

Allelic heterogeneity in hereditary surfactant protein B (SP-B) deficiency.

Inability to produce surfactant protein B (SP-B) causes fatal neonatal respiratory disease. A frame-shift mutation (121ins2) is the predominant but not exclusive cause of disease. To determine the range of mechanisms responsible for SP-B deficiency, both alleles from 32 affected infants were characterized. Sixteen infants were homozygous for the 121ins2 mutation, 10 infants were heterozygous for the 121ins2 and another mutation, and six infants were homozygous for other mutations. Thirteen novel SP-B gene mutations were identified, which were not found in a control population. One novel mutation was found in two unrelated families. Surfactant protein expression was evaluated by immunohistochemistry and/or protein blotting. Absence of proSP-B and mature SP-B was associated with nonsense and frame-shift mutations. In contrast, proSP-B expression was associated with missense mutations, or mutations causing in-frame deletions or insertions, and low levels of mature SP-B expression were associated with four mutations. Extracellular staining for proSP-C and/or aberrantly processed SP-C was observed in lungs of all infants with SP-B gene mutations. Hereditary SP-B deficiency is caused by a variety of distinct mutations in the SP-B gene and may be associated with reduced, as well as absent, levels of mature SP-B, likely caused by impaired processing of proSP-B.

Alleles↗
PubMed2000

Prolonged survival in hereditary surfactant protein B (SP-B) deficiency associated with a novel splicing mutation.

Hereditary surfactant protein B (SP-B) deficiency has been lethal in the first year of life without lung transplantation. We tested the hypothesis that SP-B gene mutations may result in milder phenotypes by investigating the mechanisms for lung disease in two children with less severe symptoms than have been previously observed in SP-B deficiency. Immunostaining patterns for pulmonary surfactant proteins were consistent with SP-B deficiency in both children. DNA sequence analysis indicated that both children were homozygous for a mutation in exon 5 that created an alternative splice site. Reverse transcriptase PCR and sequence analysis confirmed use of this splice site, which resulted in a frameshift and a premature termination codon in exon 7. The predominant reverse transcriptase PCR product, however, lacked exon 7, which restored the reading frame but would not allow translation of the exons that encode mature SP-B. Western blot analysis detected reduced amounts of mature SP-B as well as an aberrant SP-B proprotein that corresponded to the size expected from translation of the abnormal transcript. We conclude that a novel splicing mutation was the cause of lung disease in these children and that hereditary SP-B deficiency can be the cause of lung disease in older children.

Female↗
PubMed1999

Lung Kruppel-like factor, a zinc finger transcription factor, is essential for normal lung development.

Lung Kruppel-like factor (LKLF) is a member of the Kruppel-like factor family of transcription factors and is highly expressed in lung with limited distribution in other tissues. Mice lacking LKLF due to inactivation of LKLF by gene targeting die in utero at midgestation around day 12.5 due to severe hemorrhage, making it difficult to study the role of this transcription factor in lung development and function. However, in vitro organ culture of lung buds removed from 11.5-day-old LKLF(-/-) embryos show normal tracheobronchial tree formation. To examine later stages of lung development, the embryonic lethality due to germ line LKLF null mutation was circumvented by constructing LKLF homozygous null mouse embryonic stem cells, using a two-step gene targeting procedure, and determining whether these cells give rise to lung tissue. The targeted cells were used to produce chimeric animals, and the contribution of LKLF-deficient cells to the formation of various internal organs was analyzed. In chimeric mice that survived after birth, null embryonic stem cells contributed significantly to all of the major organs except the lungs. On the other hand, some highly chimeric animals died at birth, and histopathological examination of their lungs suggested abnormalities in their lung development. These studies show that LKLF plays an important role in normal lung development.

Animals↗
PubMed1999

Keratinocyte growth factor stimulates transduction of the respiratory epithelium by retroviral vectors.

Cell proliferation is required for transduction by standard retrovirus vectors derived from viruses in the murine leukemia virus (MuLV) group. Since proliferation rates are low in the mature pulmonary epithelium, we tested the hypothesis that the efficiency of retrovirus-mediated transduction of respiratory epithelial cells can be enhanced by stimulation of cell proliferation with recombinant human keratinocyte growth factor (rhKGF). A marked increase in proliferation of bronchiolar and alveolar epithelial cells was observed after intratracheal administration of rhKGF (30 mg/kg) to adult FVB/N mice. Two days after rhKGF or saline treatment, 10(7) AP+ FFU of LAPSN, a recombinant amphotropic retrovirus that expresses human placental alkaline phosphatase (AP), was instilled intratracheally into the mice. Transduction efficiency, measured 2 days after infection, was increased approximately 70-fold by rhKGF pretreatment. However, even after KGF treatment the total numbers of AP-expressing cells were few. Transduction efficiency was similar using either LAPSN packaged by amphotropic host range packaging cells or LAPSN pseudotyped with 10A1 MuLV envelope protein (0.091 +/- 0.006 versus 0.094 +/- 0.028 transduction events/mm2, respectively). Amphotropic vectors use Pit-2 for cell entry, while 10A1 MuLV vectors can use Pit-1 or Pit-2 for cell entry. By in situ hybridization the retroviral receptor Pit-2 (Ram-1) mRNA was expressed only in the pulmonary vasculature, and Pit-1 (Glvr-1) mRNA was expressed at low levels throughout the lung. In vitro studies demonstrated that retrovirus was inactivated by pulmonary surfactant. Stimulating proliferation of the respiratory epithelium increased retroviral transduction in vivo, but the paucity of retroviral receptors and inactivation by surfactant are additional barriers to high-level retroviral gene transfer in the lung.

Animals↗
PubMed1999

Congenital cystic adenomatoid malformation of the lung (CCAM): evaluation of the cellular components.

Congenital cystic adenomatoid malformation of the lung (CCAM) is a rare congenital lesion whose pathogenesis is not well defined. It is generally accepted that the various types of CCAMs originate at different levels of the tracheobronchial tree. To further define the pathogenesis of CCAM, we evaluated the cellular composition of different CCAM types by immunohistochemistry. Twenty-two CCAMs (17 CCAM type 1, two type 2, one type 3, and two type 4) were collected. The cellular composition was determined using immunohistochemical stains for type I cell-associated antigen (T1 cell-Ag), surfactant proteins and surfactant protein precursors (SP-A, SP-B, proSP-B, and proSP-C), neuroendocrine cells (GRP), Clara cells (UP-1), and the adhesion molecule CD44v6, a glycoprotein thought to be involved in cell-matrix and cell-cell interactions. Eleven fetal lungs also were analyzed to compare cytodifferentiation of the epithelial-lined cysts of the different types of CCAM with the stages of normal lung development. Our results indicate that CCAM is caused by an arrest in lung development, and, on the basis of cytodifferentiation, two major subtypes can be distinguished. One subtype consisting of CCAM types 1, 2, and 3 that shows a bronchiolar type of epithelium and a second subtype, consisting of CCAM type 4, that has an acinar-alveolar type of epithelium. Our findings also suggest that these two subtypes may arise at different stages of the branching of the bronchopulmonary tree, the first at the pseudoglandular stage and the second at the saccular stage.

Antigens, Neoplasm↗