scholarly journals Surfactant metabolic consequences of overexpression of GM-CSF in the epithelium of GM-CSF-deficient mice

1997 ◽  
Vol 273 (4) ◽  
pp. L709-L714 ◽  
Author(s):  
Machiko Ikegami ◽  
Alan H. Jobe ◽  
Jacquelyn A. Huffman Reed ◽  
Jeffrey A. Whitsett
Keyword(s):  
Lung Tissue ◽  
Surfactant Protein ◽  
Type Ii ◽  
Cell Numbers ◽  
Gm Csf ◽  
Type Ii Cell ◽  
Macrophage Colony ◽  
Respiratory Epithelial ◽  
Deficient Mice ◽  
Surfactant Metabolism

Granulocyte macrophage colony-stimulating factor (GM-CSF) is a regulator of surfactant metabolism because GM-CSF-deficient mice have abnormally slow clearance and catabolism of saturated phosphatidylcholine (Sat PC) and surfactant protein (SP)-A in airspaces and lung tissue. Overexpression of GM-CSF only in respiratory epithelial cells of mice deficient in GM-CSF using the SP-C promotor (GM−/−,SP-C-GM+/+) resulted in increased type II cell numbers and normalization of alveolar Sat PC pool sizes. Metabolic measurements demonstrated that incorporation of radiolabeled choline and palmitate was increased more than twofold, but the amount of radiolabeled Sat PC that accumulated in airspaces relative to the amount incorporated was decreased by 50% relative to normal GM+/+ mice. The clearance of dipalmitoylphosphatidylcholine and SP-B from the airspaces was more rapid for GM−/−,SP-C-GM+/+ mice than for GM+/+ mice. Loss of Sat PC and SP-B from the lungs (alveolar plus lung tissue) was similar in the two strains of mice. The normal surfactant pools in the GM−/−,SP-C-GM+/+ mice were achieved by the net effects of increases in type II cell numbers, increased incorporation, decreased accumulation, and increased reuptake rates for surfactant components, demonstrating the multiple effects of GM-CSF on surfactant metabolism.

Surfactant metabolism in transgenic mice after granulocyte macrophage-colony stimulating factor ablation

1996 ◽  
Vol 270 (4) ◽  
pp. L650-L658 ◽  
Author(s):  
M. Ikegami ◽  
T. Ueda ◽  
W. Hull ◽  
J. A. Whitsett ◽  
R. C. Mulligan ◽  
...  
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Colony Stimulating Factor ◽  
Gm Csf ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
And Function ◽  
Stimulating Factor ◽  
Deficient Mice ◽  
Surfactant Metabolism

Mice made granulocyte macrophage-colony stimulating factor (GM-CSF)-deficient by homologous recombination maintain normal steady-state hematopoiesis but have an alveolar accumulation of surfactant lipids and protein that is similar to pulmonary alveolar proteinosis in humans. We asked how GM-CSF deficiency alters surfactant metabolism and function in mice. Alveolar and lung tissue saturated phosphatidylcholine (Sat PC) were increased six- to eightfold in 7- to 9-wk-old GM-CSF-deficient mice relative to controls. Incorporation of radiolabeled palmitate and choline into Sat PC was higher in GM-CSF deficient mice than control mice, and no loss of labeled Sat PC occurred from the lungs of GM-CSF-deficient mice. Secretion of radiolabeled Sat PC to the alveolus was similar in GM-CSF-deficient and control mice. Labeled Sat PC and surfactant protein A (SP-A) given by tracheal instillation were cleared rapidly in control mice, but there was no measurable loss from the lungs of GM-CSF-deficient mice. The function of the surfactant from GM-CSF-deficient mice was normal when tested in preterm surfactant-deficient rabbits. GM-CSF deficiency results in a catabolic defect for Sat PC and SP-A.

GM-CSF mediates alveolar macrophage proliferation and type II cell hypertrophy in SP-D gene-targeted mice

2001 ◽  
Vol 280 (6) ◽  
pp. L1148-L1156 ◽  
Author(s):  
Samuel Hawgood ◽  
Jennifer Akiyama ◽  
Cynthia Brown ◽  
Lennell Allen ◽  
Gordon Li ◽  
...  
Keyword(s):  
Alveolar Macrophage ◽  
Surfactant Protein ◽  
Type Ii Cells ◽  
Type Ii ◽  
Gm Csf ◽  
Cell Hypertrophy ◽  
Alveolar Surfactant ◽  
Type Ii Cell ◽  
Macrophage Colony ◽  
Foamy Macrophages

Mice deficient in surfactant protein (SP) D develop increased surfactant pool sizes and dramatic changes in alveolar macrophages and type II cells. To test the hypothesis that granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates alveolar macrophage proliferation and activation and the type II cell hypertrophy seen in SP-D null mice, we bred SP-D and GM-CSF gene-targeted mice to obtain littermate double null, single null, and wild-type mice. Bronchoalveolar lavage levels of phospholipid, protein, SP-D, SP-A, and GM-CSF were measured from 1 to 4 mo. There was an approximately additive accumulation of phospholipid, total protein, and SP-A at each time point. Microscopy showed normal macrophage number and morphology in GM-CSF null mice, numerous giant foamy macrophages and hypertrophic type II cells in SP-D null mice, and large but not foamy macrophages and mostly normal type II cells in double null mice. These results suggest that the mechanisms underlying the alveolar surfactant accumulation in the SP-D-deficient and GM-CSF-deficient mice are different and that GM-CSF mediates some of the macrophage and type II cell changes seen in SP-D null mice.

Surfactant metabolism in surfactant protein A-deficient mice

1997 ◽  
Vol 272 (3) ◽  
pp. L479-L485 ◽  
Author(s):  
M. Ikegami ◽  
T. R. Korfhagen ◽  
M. D. Bruno ◽  
J. A. Whitsett ◽  
A. H. Jobe
Keyword(s):  
Lung Tissue ◽  
Protein A ◽  
Surfactant Protein ◽  
Normal Lung ◽  
Tissue Slices ◽  
Normal Lung Function ◽  
Deficient Mice ◽  
Surfactant Metabolism

In the present study we asked if surfactant metabolism was altered in surfactant protein (SP) A-deficient mice in vivo. Although previous studies in vitro demonstrated that SP-A modulates surfactant secretion and reuptake by type II cells, mice made SP-A deficient by homologous recombination grow and reproduce normally and have normal lung function. Alveolar and lung tissue saturated phophatidylcholine (Sat PC) pools were 50 and 26% larger, respectively, in SP-A(-/-) mice than in SP-A(+/+) mice. Radiolabeled choline and palmitate incorporation into lung Sat PC was similar both in vivo and for lung tissue slices in vitro from SP-A(+/+) and SP-A(-/-) mice. Percent secretion of radiolabeled Sat PC was unchanged from 3 to 15 h, although SP-A(-/-) mice retained more labeled Sat PC in the alveolar lavages at 48 h (consistent with the increased surfactant pool sizes). Clearance of radiolabeled dipalmitoylphosphatidylcholine and SP-B from the air spaces after intratracheal injection was similar in SP-A(-/-) and SP-A(+/+) mice. Lack of SP-A had minimal effects on the overall metabolism of Sat PC or SP-B in mice.

GM-CSF mediates alveolar epithelial type II cell changes, but not emphysema-like pathology, in SP-D-deficient mice

2004 ◽  
Vol 287 (6) ◽  
pp. L1333-L1341 ◽  
Author(s):  
Matthias Ochs ◽  
Lars Knudsen ◽  
Lennell Allen ◽  
Amber Stumbaugh ◽  
Stacey Levitt ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Immune Response Gene ◽  
Surfactant Protein D ◽  
Type Ii Cells ◽  
Type Ii ◽  
Cell Hyperplasia ◽  
Alveolar Epithelial ◽  
Gm Csf ◽  
Type Ii Cell ◽  
Deficient Mice

Surfactant protein D (SP-D) is a member of the collectin subfamily of C-type lectins, pattern recognition proteins participating in the innate immune response. Gene-targeted mice deficient in SP-D develop abnormalities in surfactant homeostasis, hyperplasia of alveolar epithelial type II cells, and emphysema-like pathology. Granulocyte/macrophage colony-stimulating factor (GM-CSF) is required for terminal differentiation and subsequent activation of alveolar macrophages, including the expression of matrix metalloproteinases and reactive oxygen species, factors thought to contribute to lung remodeling. Type II cells also express the GM-CSF receptor. Thus we hypothesized GM-CSF might mediate some or all of the cellular and structural abnormalities in the lungs of SP-D-deficient mice. To test this, SP-D (D−G+) and GM-CSF (D+G−) single knockout mice as well as double knockout mice deficient for both SP-D and GM-CSF (D−G−) were analyzed by design-based stereology. Compared with wild type, D−G+ as well as D+G− mice showed decreased alveolar numbers, increased alveolar sizes, and decreased alveolar epithelial surface areas. These emphysema-like changes were present to a greater extent in D−G− mice. D−G+ mice developed type II cell hyperplasia and hypertrophy with increased intracellular surfactant pools, whereas D+G− mice had smaller type II cells with decreased intracellular surfactant pools. In contrast to the emphysematous changes, the type II cell alterations were mostly corrected in D−G− mice. These results indicate that GM-CSF-dependent macrophage activity is not necessary for emphysema development in SP-D-deficient mice, but that type II cell metabolism and proliferation are, either directly or indirectly, regulated by GM-CSF in this model.

Distinct changes in pulmonary surfactant homeostasis in common β-chain- and GM-CSF-deficient mice

2000 ◽  
Vol 278 (6) ◽  
pp. L1164-L1171 ◽  
Author(s):  
Jacquelyn A. Reed ◽  
Machiko Ikegami ◽  
Lorraine Robb ◽  
C. Glenn Begley ◽  
Gary Ross ◽  
...  
Keyword(s):  
Surfactant Protein ◽  
Wild Type ◽  
Gm Csf ◽  
Adult Mice ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Β Chain ◽  
Stimulating Factor ◽  
Surfactant Metabolism ◽  
Pool Sizes

Pulmonary alveolar proteinosis (PAP) is caused by inactivation of either granulocyte-macrophage colony-stimulating factor (GM-CSF) or GM receptor common β-chain (βc) genes in mice [GM(−/−), βc(−/−)], demonstrating a critical role of GM-CSF signaling in surfactant homeostasis. To distinguish possible phenotypic differences in GM(−/−) and βc(−/−) mice, surfactant metabolism was compared in βc(−/−), GM(−/−), and wild-type mice. Although lung histology in βc(−/−) and GM(−/−) mice was indistinguishable, distinct differences were observed in surfactant phospholipid and surfactant protein concentrations and clearance from lungs of βc(−/−) and GM(−/−) mice. At 1–2 days of age, lung saturated phosphatidylcholine (Sat PC) pool sizes were higher in wild-type, βc(−/−), and GM(−/−) mice compared with wild-type adult mice. In wild-type mice, Sat PC pool sizes decreased to adult levels by 7 days of age; however, Sat PC increased with advancing age in βc(−/−) and GM(−/−) mice. Postnatal changes in Sat PC pool sizes were different in GM(−/−) compared with βc(−/−) mice. After 7 days of age, the increased lung Sat PC pool sizes remained constant in βc(−/−) mice but continued to increase in GM(−/−) mice, so that by 56 days of age, lung Sat PC pools were increased three- and sixfold, respectively, compared with wild-type controls. After intratracheal injection, the percent recovery of [3H]dipalmitoylphosphatidylcholine and125I-recombinant surfactant protein (SP) C was higher in βc(−/−) compared with wild-type mice, reflecting decreased clearance in the receptor-deficient mice. The defect in clearance was significantly more severe in GM(−/−) than in βc(−/−) mice. The ratio of SP Sat PC to SP-A, -B, and -C was similar in bronchoalveolar lavage fluid (BALF) from adult mice of all genotypes, but the ratio of SP-D to Sat PC was markedly increased in βc(−/−) and GM(−/−) mice (10- and 5-fold, respectively) compared with wild-type mice. GM-CSF concentrations were increased in BALF but not in serum of βc(−/−) mice, consistent with a pulmonary response to the lack of GM-CSF signaling. The observed differences in surfactant metabolism suggest the presence of alternative clearance mechanisms regulating surfactant homeostasis in βc(−/−) and GM(−/−) mice and may provide a molecular basis for the range in severity of PAP symptoms. surfactant metabolism; alveolar macrophage; granulocyte-macrophage colony-stimulating factor

Processing of surfactant protein B proprotein by a cathepsin D-like protease

1992 ◽  
Vol 263 (1) ◽  
pp. L95-L103 ◽  
Author(s):  
T. E. Weaver ◽  
S. Lin ◽  
B. Bogucki ◽  
C. Dey
Keyword(s):  
Epithelial Cell ◽  
Cell Membrane ◽  
Cathepsin D ◽  
Surfactant Protein ◽  
Membrane Preparation ◽  
Aspartyl Protease ◽  
Type Ii ◽  
Surfactant Protein B ◽  
Type Ii Cell ◽  
Cell Membrane Preparation

Surfactant protein B (SP-B) is a hydrophobic peptide of relative molecular weight (M(r)) = 8,000 that is associated with pulmonary surfactant phospholipids. SP-B is synthesized by the alveolar type II epithelial cell as a proprotein of M(r) = 42,000 which requires at least two proteolytic cleavages to generate the 79 residue mature SP-B peptide. We have previously reported that cleavage of the NH2-terminal propeptide, to generate a processing intermediate of M(r) = 25,000, occurs in close temporal approximation to secretion. In the present study we demonstrate that SP-B proprotein, isolated from stably transfected Chinese hamster ovary cells, is processed to M(r) = 25,000 by a crude type II cell membrane fraction but not by intact type II cells or type II cell conditioned media. In vitro processing of the proprotein by the type II cell membrane preparation resulted in release of a single peptide of M(r) = 16,000–17,000, which was detected by antiserum directed against antigenic epitopes in propeptide of the precursor. SP-B processing activity was extracted by Na2CO3 lysis of the type II cell membrane preparation, had a pH optimum of 5.0–6.0, and was inhibited by 10(-7) M pepstatin A, suggesting that the NH2-terminal peptide of the precursor is cleaved by an aspartyl protease. Consistent with this hypothesis, processing of SP-B by a crude type II cell membrane preparation was blocked by antiserum directed against the aspartyl protease cathepsin D; further, purified cathepsin D efficiently processed the SP-B precursor to M(r) = 25,000. Collectively these results suggest that cleavage of the NH2-terminal propeptide of the SP-B precursor is mediated by cathepsin D or a cathepsin D-like protease localized within the secretory pathway of the type II epithelial cell.

Ontogeny of rat lung type II cells correlated with surfactant lipid and surfactant apoprotein expression

1991 ◽  
Vol 260 (6) ◽  
pp. L562-L570 ◽  
Author(s):  
S. H. Randell ◽  
R. Silbajoris ◽  
S. L. Young
Keyword(s):  
Lung Tissue ◽  
Lamellar Body ◽  
Alveolar Epithelium ◽  
Cell Number ◽  
Body Volume ◽  
Type Ii ◽  
Lung Weight ◽  
Type Ii Cell ◽  
Surfactant Lipid ◽  
Surfactant Apoprotein

During the last stages of intrauterine growth, remarkable changes occur in the alveolar epithelium that include cellular differentiation and increased production of surfactant lipid and apoprotein. We made morphometric measurements of type II cell characteristics from rats aged gestational day 20 to 14 days postnatal. We also measured the amounts of disaturated phosphatidylcholine (DSPC) and surfactant apoprotein (SP-A) in lung tissue, bronchoalveolar lavage, and a lamellar body-rich fraction, and we estimated the lung content of mRNAs for SP-A, SP-B, and SP-C. Lavage and lamellar body surfactant lipid and apoprotein content per lung showed a pattern of a sharp rise in the early postnatal period, then a substantial decline, and a second increase by day 14. When normalized for dry lung weight, the highest DSPC values were found on postnatal day 1 in all compartments. The fraction of whole lung DSPC found in lamellar body or lavage was greatest in the 48-h period surrounding birth. Lamellar body SP-A was greater than lavage SP-A on gestational day 22, but a day later the lavage SP-A was 16 times greater than the lamellar body SP-A. The lung tissue content of all three apoprotein mRNAs increased sharply before birth, fell during the 1st postnatal wk, and then rose again to adult levels. Type II cell number and lamellar body number per milligram of dry lung tissue was highest on post-natal day 1 and fell by one-half during the 1st postnatal wk. The amount of DSPC per unit of lamellar body volume rose to its greatest value on postnatal day 1 and then decreased more than threefold. These findings indicate a pattern of expansion of surfactant cellular and biochemical pools at the time of birth in the rat.

Transcriptional activation and protein binding by two regions of the rat surfactant protein A promoter

1999 ◽  
Vol 277 (1) ◽  
pp. L134-L141
Author(s):  
Elizabeth Rosenberg ◽  
Feng Li ◽  
Candyce I. Smith ◽  
Samuel R. Reisher ◽  
Sheldon I. Feinstein
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Promoter Activity ◽  
Protein A ◽  
Surfactant Protein ◽  
Clara Cell ◽  
Surfactant Protein A ◽  
Type Ii ◽  
Recognition Element ◽  
Type Ii Cell

Surfactant protein A (SP-A) is expressed in lung alveolar type II cells and bronchiolar Clara cells. We have identified two active regions in the promoter of the rat SP-A gene by deletion analysis of a plasmid containing 163 bp before the start of transcription (−163 bp), linked to a reporter gene. Constructs were transfected into lung cell lines derived from each of the cell types that produces SP-A. We found a novel region of promoter activity at ∼90 bp before the transcriptional start (SP-A−90). Mutation of four nucleotides in SP-A−90 that are highly conserved among species (−92 to −89 bp) decreased expression of the SP-A construct by ∼50% in both cell lines. Electrophoretic mobility shift analysis showed specific binding to SP-A−90 by nuclear proteins from the cell lines, as well as from rat lung and liver. The electrophoretic mobility of the bands shifted by lung nuclear proteins changed late in fetal development. Although in the Clara cell line no reduction of promoter activity was seen on deletion of the region upstream of SP-A−90, in the type II cell line, deletion of residues −163 to −133 did reduce activity by ∼50%. This region contains a recognition element for thyroid transcription factor-1 (TTF-1). Endogenous TTF-1 binding activity was substantially higher in the type II cell line than in the Clara cell line, but cotransfection of a TTF-1 expression plasmid enhanced expression of the SP-A construct better in the Clara cell line than in the type II cell line. These results suggest that the recognition element for TTF-1 has varying activity in the lung cell lines of different origin due to the availability of TTF-1.

Sign in / Sign up

Export Citation Format

Share Document