Composition of human pulmonary surfactant varies with exercise and level of fitness.

Doyle, Ian; Jones, Michael E.; Barr, Heather A.; Orgeig, Sandra; Crockett, Alan; McDonald, Christine F; Nicholas, Terence E.

doi:10.1164/ajrccm.149.6.8004321

Cited by 68 publications

(36 citation statements)

References 32 publications

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“…In contrast to the results of the previous study, the concentrations of red blood cells, total protein, and LTB 4 in the BAL fluid of the exercising athletes were not different from those of the control subjects. There were higher concentrations of surfactant apoprotein A in the athletes, but this is known to occur with exercise (50). The general conclusion of these studies is that the integrity of the blood-gas barrier in normal healthy humans is altered only at extreme levels of exercise, and indeed this is what might be expected on general evolutionary lines.…”

Section: G Physiological Conditions Under Which Stress Failure Occursmentioning

confidence: 75%

Thin and Strong! The Bioengineering Dilemma in the Structural and Functional Design of the Blood-Gas Barrier

Maina¹,

West²

2005

Physiological Reviews

173

159

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In gas exchangers, the tissue barrier, the partition that separates the respiratory media (water/air and hemolymph/blood), is exceptional for its remarkable thinness, striking strength, and vast surface area. These properties formed to meet conflicting roles: thinness was essential for efficient flux of oxygen by passive diffusion, and strength was crucial for maintaining structural integrity. What we have designated as "three-ply" or "laminated tripartite" architecture of the barrier appeared very early in the evolution of the vertebrate gas exchanger. The design is conspicuous in the water-blood barrier of the fish gills through the lungs of air-breathing vertebrates, where the plan first appeared in lungfishes (Dipnoi) some 400 million years ago. The similarity of the structural design of the barrier in respiratory organs of animals that remarkably differ phylogenetically, behaviorally, and ecologically shows that the construction has been highly conserved both vertically and horizontally, i.e., along and across the evolutionary continuum. It is conceivable that the blueprint may have been the only practical construction that could simultaneously grant satisfactory strength and promote gas exchange. In view of the very narrow allometric range of the thickness of the blood-gas barrier in the lungs of different-sized vertebrate groups, the measurement has seemingly been optimized. There is convincing, though indirect, evidence that the extracellular matrix and particularly the type IV collagen in the lamina densa of the basement membrane is the main stress-bearing component of the blood-gas barrier. Under extreme conditions of operation and in some disease states, the barrier fails with serious consequences. The lamina densa which in many parts of the blood-gas barrier is <50 nm thin is a lifeline in the true sense of the word.

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Section: G Physiological Conditions Under Which Stress Failure Occursmentioning

confidence: 75%

Thin and Strong! The Bioengineering Dilemma in the Structural and Functional Design of the Blood-Gas Barrier

Maina¹,

West²

2005

Physiological Reviews

173

159

View full text Add to dashboard Cite

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“…Lung surfactant is composed of 80% glycerophospholipid, 10% cholesterol and 10% protein; the amount of cholesterol within the surfactant can increase relative to the phospholipid content under certain conditions, including exercise (Doyle et al, 1994) and hyperpnea (Orgeig et al, 2003). In lung MLBs, cholesterol is localized primarily to the limiting membrane of the organelle (Orgeig, 2001) and whether MLBs are the source of surfactant cholesterol remains uncertain (Hass and Longmore, 1979;Orgeig et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

The lipid composition of autophagic vacuoles regulates expression of multilamellar bodies

Lajoie

Guay

Dennis

et al. 2005

Journal of Cell Science

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Multilamellar bodies (MLBs) are responsible for surfactant secretion in type II alveolar cells but also accumulate in other cell types under pathological conditions, including cancer and lysosomal storage diseases such as Niemann-Pick C (NPC), a congenital disease where defective cholesterol transport leads to its accumulation in lysosomes. Mv1Lu type II alveolar cells transfected with Golgi β1,6 N-acetylglucosaminyltransferase V (Mgat5), enhancing the polylactosamine content of complex-type N-glycans, exhibit stable expression of MLBs whose formation requires lysosomal proteolysis within dense autophagic vacuoles. MLBs of Mgat5-transfected Mv1Lu cells are rich in phospholipids and have low levels of cholesterol. In Mv1Lu cells treated with the NPC-mimicking drug U18666A, cholesterol-rich MLBs accumulate independently of both Mgat5 expression and lysosomal proteolysis. Inhibition of autophagy by blocking the PI 3-kinase pathway with 3-methyladenine prevents MLB formation and results in the accumulation of non-lamellar, acidic lysosomal vacuoles. Treatment with 3-methyladenine inhibited the accumulation of monodansylcadaverine, a phospholipid-specific marker for autophagic vacuoles, but did not block endocytic access to the lysosomal vacuoles. Induction of autophagy via serum starvation resulted in an increased size of cholesterol-rich MLBs. Although expression of MLBs in the Mv1Lu cell line can be induced by modulating lysosomal cholesterol or protein glycosylation, an autophagic contribution of phospholipids is critical for the formation of concentric membrane lamellae within late lysosomal organelles.

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“…Splice 5Ј UTR variants were recently shown to differentially affect translation and mRNA stability (62). Differences in SP-A protein content levels among individuals have been observed in cases of lung disease, including CF (20,24,52,57), or in physiological changes in lung activity (12). In these cases, no distinction was made between SP-A1 and SP-A2 content or SP-A genotype.…”

mentioning

confidence: 99%

Surfactant Protein A2 (SP-A2) Variants Expressed in CHO Cells Stimulate Phagocytosis of Pseudomonas aeruginosa More than Do SP-A1 Variants

Mikerov¹,

Wang²,

Umstead

et al. 2007

Infect Immun

112

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Surfactant protein A (SP-A) enhances phagocytosis of Pseudomonas aeruginosa. Two functional genes, SP-A1and SP-A2, encode human SP-A. As we showed before, baculovirus-mediated insect cell-expressed SP-A2 enhances the association of P. aeruginosa with rat alveolar macrophages (rAMs) more than does SP-A1. However, true phagocytosis (internalization) was not shown, and insect cell derived proteins lack or are defective in certain mammalian posttranslational modifications that may be important for SP-A1 and SP-A2 activity and specificity. Here we used SP-A1 (6A 2 , 6A 4 ) and SP-A2 (1A 0 , 1A 1 ) allele variants expressed by CHO (Chinese hamster ovary) mammalian cells to study their effect on association and/or internalization of P. aeruginosa by rAMs and/or human AMs (hAMs) and to study if phagocytosis can be modulated differentially and/or more effectively by CHO cell-expressed SP-A variants than by insect-cell expressed SP-A variants. For cell association and internalization assessments, light microscopy and fluorescence-activated cell sorter analyses were used, respectively. We found the following for the first time.

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Composition of human pulmonary surfactant varies with exercise and level of fitness.

Cited by 68 publications

References 32 publications

Thin and Strong! The Bioengineering Dilemma in the Structural and Functional Design of the Blood-Gas Barrier

Thin and Strong! The Bioengineering Dilemma in the Structural and Functional Design of the Blood-Gas Barrier

The lipid composition of autophagic vacuoles regulates expression of multilamellar bodies

Surfactant Protein A2 (SP-A2) Variants Expressed in CHO Cells Stimulate Phagocytosis of Pseudomonas aeruginosa More than Do SP-A1 Variants

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