Localization of surfactant protein A (SP-A) in alveolar macrophage subpopulations of normal and fibrotic rat lung

Previous studies have shown that surfactant protein A (SP-A) derived from alveolar-proteinosis patients activates rat alveolar macrophages. However, it is not known if normal rat, dog and human SP-A can also stimulate alveolar macrophages. As alveolar-proteinosis SP-A has a slightly different structure from ordinary SP-A, it would be possible that the ascribed alveolar-macrophage-stimulating properties of SP-A are restricted to alveolar-proteinosis SP-A. To clarify this issue, we isolated SP-A from normal rat and dog pulmonary surfactants, using the same isolation technique commonly used for the isolation of alveolar-proteinosis SP-A, i.e. by butanol precipitation. In contrast with human alveolar-proteinosis SP-A, rat and dog SP-A obtained thus could not activate rat alveolar macrophages to produce oxygen radicals or enhance the phagocytosis of fluorescein isothiocyanate-labelled herpes simplex virus. However, rat, dog and normal human SP-A isolated by a novel method, involving extraction from pulmonary surfactant by using n-octyl beta-D-glucopyranoside and subsequent purification by cation-exchange chromatography, were able to elicit an oxidative burst in rat as well as normal human alveolar macrophages. In addition, dog and rat SP-A obtained thus stimulated the phagocytosis of herpes simplex virus by rat alveolar macrophages. These findings indicate that normal human, rat and dog SP-A have the same alveolar-macrophage-stimulating properties as human alveolar proteinosis SP-A. Dog and rat SP-A isolated by this novel method had the same Ca(2+)-dependent self-aggregation and lipid-aggregation properties as SP-A isolated by butanol precipitation. The new and milder isolation procedure yielded SP-A of high purity, as judged by SDS/PAGE and ELISA.

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Distribution of surfactant protein A in rat lung.

American Journal of Respiratory Cell and Molecular Biology ◽

10.1165/ajrcmb.11.4.7917309 ◽

1994 ◽

Vol 11 (4) ◽

pp. 405-415 ◽

Cited By ~ 18

Author(s):

I R Doyle ◽

H A Barr ◽

T E Nicholas

Keyword(s):

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Rat Lung

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ATP and adenosine 3',5'-cyclic monophosphate stimulate the synthesis of surfactant protein A in rat lung

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1993.264.5.l431 ◽

1993 ◽

Vol 264 (5) ◽

pp. L431-L437 ◽

Cited By ~ 15

Author(s):

A. Wali ◽

M. F. Beers ◽

C. Dodia ◽

S. I. Feinstein ◽

A. B. Fisher

Keyword(s):

Total Protein ◽

Protein A ◽

Lamellar Body ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Enzyme Linked Immunosorbent Assay ◽

Translational Efficiency ◽

Rat Lung ◽

Body Protein ◽

Cyclic Monophosphate

Synthesis and secretion of surfactant protein A (SP-A) were studied in the isolated perfused rat lung using Trans35S-label (approximately 85% methionine, 15% cysteine) in the perfusate with or without 1 mM ATP or 0.1 mM 8-bromoadenosine 3',5',-cyclic monophosphate (8-BrcAMP) for up to 6 h of perfusion. By enzyme-linked immunosorbent assay, the SP-A content was 36 +/- 0.3% of total protein in extracellular surfactant and 10.8 +/- 1.9% of total protein in lamellar bodies of control lungs; these relativr proportions were maintained in the presence of ATP or 8-BrcAMP. Incorporation of [35S]methionine (cysteine) into the surfactant and lamellar body protein fraction could be detected at 4 h of perfusion. At 6 h, specific activity of total protein [disintegrations per minute (dpm)/micrograms)] was significantly increased in both the surfactant (54%) and lamellar body fractions (30%) under the influence of either secretagogue compared with control conditions. In the presence of ATP, there was a significant increase in the SP-A immunoprecipitable counts of 61 and 72% in extra- and intracellular compartments, respectively. However, no significant change was observed in the relative abundance of SP-A mRNA between control and secretagogue-treated lungs. This dissociation of SP-A mRNA abundance and label incorporation into protein indicates that alteration in translational efficiency or posttranslational factors may be involved in the secretagogue-induced stimulation of SP-A synthesis.

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Impact of Surfactant Protein A (SP-A) Variants on Alveolar Macrophage Gene Expression in Response to Klebsiella Pneumoniae Infection and Sex Differences

10.1164/ajrccm-conference.2020.201.1_meetingabstracts.a2963 ◽

2020 ◽

Author(s):

N. Thorenoor ◽

Y.I. Kawasawa ◽

C. Gandhi ◽

X. Zhang ◽

J. Floros

Keyword(s):

Gene Expression ◽

Sex Differences ◽

Klebsiella Pneumoniae ◽

Alveolar Macrophage ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A

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Alveolar uptake of lipid and protein components of surfactant

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1991.261.4.l334 ◽

1991 ◽

Vol 261 (4) ◽

pp. L334-L340 ◽

Cited By ~ 13

Author(s):

A. B. Fisher ◽

C. Dodia ◽

A. Chander

Keyword(s):

Plasma Membranes ◽

Protein A ◽

Surfactant Protein ◽

Lung Lavage ◽

Surfactant Protein A ◽

Rat Lung ◽

Protein Breakdown ◽

Aqueous Fraction ◽

Natural Surfactant ◽

Protein Components

We investigated the clearance of radiolabeled natural surfactant from the alveolar space of the isolated perfused rat lung. 3H, 35S-natural surfactant was prepared from rat lungs that had been perfused with [methyl-3H]choline and [35S]methionine. The biosynthesized material contained greater than 95% of 3H in phosphatidylcholine (PC) and approximately 80% of 35S in surfactant protein A. Natural surfactant (1 mumol PC) was instilled into the trachea; lungs were analyzed 5 min later or after 2 h perfusion to determine surfactant uptake, defined as lung lavage-resistant 3H or 35S [% of instilled disintegrations per minute(dpm)]. Uptake at 5 min was 31.4 +/- 0.37% for 3H and 31.9 +/- 0.85% for 35S (mean +/- SE, n = 4). At 2 h, uptake was 46.6 +/- 0.96% for 3H and 45.8 +/- 1.1% for 35S (n = 7). In the presence of 0.1 mM 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP), uptake at 2 h for both 3H and 35S was stimulated to approximately 57% of instilled dpm (n = 4). Microsomes and plasma membranes isolated from lung homogenates had a ratio of 3H to 35S that was similar to the original surfactant, whereas 3H/35S in isolated lamellar bodies was increased 2.1-fold. Degradation of lipid was indicated by finding 13.4 +/- 0.65% of homogenate 3H in the aqueous fraction of lung extract after 2 h perfusion; only 2.3 +/- 0.47% of 35S dpm were soluble in trichloroacetic acid, suggesting significantly less protein breakdown. Lipid degradation was increased more than twofold by 8-BrcAMP, whereas protein degradation was not changed significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

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Surfactant protein A is localized at the corners of the pulmonary tubular myelin lattice.

Journal of Histochemistry & Cytochemistry ◽

10.1177/39.10.1940306 ◽

1991 ◽

Vol 39 (10) ◽

pp. 1331-1336 ◽

Cited By ~ 76

Author(s):

W F Voorhout ◽

T Veenendaal ◽

H P Haagsman ◽

A J Verkleij ◽

L M van Golde ◽

...

Keyword(s):

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A ◽

Alveolar Type ◽

Type Ii ◽

Rat Lung ◽

Lamellar Bodies ◽

20 Nm

Immunogold labeling on sections of a freeze-substituted tubular myelin-enriched fraction isolated from a bronchoalveolar lavage of rat lung showed that surfactant protein A (SP-A) occurs predominantly at the corners of the tubular myelin lattice. Seventy-nine percent of the gold particles were located within 20 nm from a corner. Extracellular SP-A was detected only in the tubular myelin lattice and not in vesicles or secreted lamellar bodies. Ultra-thin cryosections of rat lung fixed in vivo showed that intracellular SP-A was distributed homogeneously over the stacked membranes of lamellar bodies in alveolar Type II cells. The presence of SP-A at the corners of the tubular myelin lattice suggests an important role of this protein in the formation and/or maintenance of this highly ordered lattice.

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