Dipalmitoylphosphatidylcholine is not the major surfactant phospholipid species in all mammals

2005 ◽  
Vol 289 (5) ◽  
pp. R1426-R1439 ◽  
Author(s):  
Carol J. Lang ◽  
Anthony D. Postle ◽  
Sandra Orgeig ◽  
Fred Possmayer ◽  
Wolfgang Bernhard ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Animal Species ◽  
Protein A ◽  
Complex Mixture ◽  
Surfactant Protein ◽  
Tasmanian Devil ◽  
Surfactant Protein B ◽  
Surfactant Composition ◽  
Phospholipid Species

Pulmonary surfactant, a complex mixture of lipids and proteins, lowers the surface tension in terminal air spaces and is crucial for lung function. Within an animal species, surfactant composition can be influenced by development, disease, respiratory rate, and/or body temperature. Here, we analyzed the composition of surfactant in three heterothermic mammals (dunnart, bat, squirrel), displaying different torpor patterns, to determine: 1) whether increases in surfactant cholesterol (Chol) and phospholipid (PL) saturation occur during long-term torpor in squirrels, as in bats and dunnarts; 2) whether surfactant proteins change during torpor; and 3) whether PL molecular species (molsp) composition is altered. In addition, we analyzed the molsp composition of a further nine mammals (including placental/marsupial and hetero-/homeothermic contrasts) to determine whether phylogeny or thermal behavior determines molsp composition in mammals. We discovered that like bats and dunnarts, surfactant Chol increases during torpor in squirrels. However, changes in PL saturation during torpor may not be universal. Torpor was accompanied by a decrease in surfactant protein A in dunnarts and squirrels, but not in bats, whereas surfactant protein B did not change in any species. Phosphatidylcholine (PC)16:0/16:0 is highly variable between mammals and is not the major PL in the wombat, dunnart, shrew, or Tasmanian devil. An inverse relationship exists between PC16:0/16:0 and two of the major fluidizing components, PC16:0/16:1 and PC16:0/14:0. The PL molsp profile of an animal species is not determined by phylogeny or thermal behavior. We conclude that there is no single PL molsp composition that functions optimally in all mammals; rather, surfactant from each animal is unique and tailored to the biology of that animal.

Macrophages primed by overnight culture demonstrate a marked stimulation of surfactant protein A degradation

1997 ◽  
Vol 273 (4) ◽  
pp. L831-L839 ◽  
Author(s):  
Sandra R. Bates ◽  
Jin Xu ◽  
Chandra Dodia ◽  
Aron B. Fisher
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Prolonged Culture ◽  
Primed State ◽  
Elevated Rate ◽  
Hand Length ◽  
Macrophage Uptake ◽  
Overnight Culture

The current study examined whether long-term culture of macrophages affects their metabolism of surfactant components. Compared with freshly isolated resting macrophages in culture for 1 h, macrophages attached to plastic dishes for 24 h showed evidence of conversion to a “primed” state with 1) an altered morphology characterized by a larger size, ruffled membranes, lamellipodia, and a “foamy” appearance after attachment to glass and 2) a fivefold greater respiratory burst in response to phorbol 12-myristate 13-acetate stimulation. On incubation with iodinated surfactant protein A (SP-A), the 24-h alveolar or tissue macrophages showed a 5- or a 23-fold greater increase in SP-A degradation, respectively, than macrophages cultured for 1 h. Conditioned media experiments demonstrated that the elevated rate of SP-A degradation after prolonged culture was not a result of proteases secreted by the macrophages. Incubation of cells with NH4Cl reduced the degradation of SP-A to a similar extent (to 33% of control values) in resting and primed tissue macrophages. On the other hand, length of time of cell culture did not affect macrophage uptake and degradation of [3H]dipalmitoylphosphatidylcholine in mixed unilamellar liposomes. Thus freshly isolated resting tissue and alveolar macrophages can be primed to specifically increase their rate of SP-A degradation. Activation of macrophages associated with lung disease may be important for SP-A metabolism and surfactant function.

Long-term outcomes after infant lung transplantation for surfactant protein B deficiency related to other causes of respiratory failure

2006 ◽  
Vol 149 (4) ◽  
pp. 548-553 ◽  
Author(s):  
Lisanne M. Palomar ◽  
Lawrence M. Nogee ◽  
Stuart C. Sweet ◽  
Charles B. Huddleston ◽  
F. Sessions Cole ◽  
...  
Keyword(s):  
Respiratory Failure ◽  
Lung Transplantation ◽  
Surfactant Protein ◽  
Long Term Outcomes ◽  
Surfactant Protein B ◽  
Surfactant Protein B Deficiency ◽  
Protein B

scholarly journals Pulmonary surfactant protein A and surfactant lipids upregulate IRAK-M, a negative regulator of TLR-mediated inflammation in human macrophages

2012 ◽  
Vol 303 (7) ◽  
pp. L608-L616 ◽  
Author(s):  
Huy A. Nguyen ◽  
Murugesan V. S. Rajaram ◽  
Douglas A. Meyer ◽  
Larry S. Schlesinger
Keyword(s):  
Proinflammatory Cytokine ◽  
Cytokine Production ◽  
Protein A ◽  
Surfactant Protein ◽  
Negative Regulator ◽  
Surfactant Protein A ◽  
Proinflammatory Cytokine Production ◽  
Human Macrophages ◽  
Tnf Α

Alveolar macrophages (AMs) are exposed to frequent challenges from inhaled particulates and microbes and function as a first line of defense with a highly regulated immune response because of their unique biology as prototypic alternatively activated macrophages. Lung collectins, particularly surfactant protein A (SP-A), contribute to this activation state by fine-tuning the macrophage inflammatory response. During short-term (10 min–2 h) exposure, SP-A's regulation of human macrophage responses occurs through decreased activity of kinases required for proinflammatory cytokine production. However, AMs are continuously exposed to surfactant, and the biochemical pathways underlying long-term reduction of proinflammatory cytokine activity are not known. We investigated the molecular mechanism(s) underlying SP-A- and surfactant lipid-mediated suppression of proinflammatory cytokine production in response to Toll-like receptor (TLR) 4 (TLR4) activation over longer time periods. We found that exposure of human macrophages to SP-A for 6–24 h upregulates expression of IL-1 receptor-associated kinase M (IRAK-M), a negative regulator of TLR-mediated NF-κB activation. Exposure to Survanta, a natural bovine lung extract lacking SP-A, also enhances IRAK-M expression, but at lower magnitude and for a shorter duration than SP-A. Surfactant-mediated upregulation of IRAK-M in macrophages suppresses TLR4-mediated TNF-α and IL-6 production in response to LPS, and IRAK-M knockdown by small interfering RNA reverses this suppression. In contrast to TNF-α and IL-6, the surfactant components upregulate LPS-mediated immunoregulatory IL-10 production, an effect reversed by IRAK-M knockdown. In conclusion, these data identify an important signaling regulator in human macrophages that is used by surfactant to control the long-term alveolar inflammatory response, i.e., enhanced IRAK-M activity.

scholarly journals Surfactant protein B inhibits secretory phospholipase A2 hydrolysis of surfactant phospholipids

2012 ◽  
Vol 302 (2) ◽  
pp. L257-L265 ◽  
Author(s):  
R. Duncan Hite ◽  
Bonnie L. Grier ◽  
B. Moseley Waite ◽  
Ruud A. Veldhuizen ◽  
Fred Possmayer ◽  
...  
Keyword(s):  
Protein A ◽  
Lipid Vesicles ◽  
Surfactant Protein ◽  
Airway Diseases ◽  
Surfactant Protein B ◽  
Monomolecular Films ◽  
Alveolar Surfactant ◽  
Surfactant Phospholipids ◽  
Air Liquid Interface ◽  
Hydrolysis Of

Hydrolysis of surfactant phospholipids (PL) by secretory phospholipases A2 (sPLA2) contributes to surfactant damage in inflammatory airway diseases such as acute lung injury/acute respiratory distress syndrome. We and others have reported that each sPLA2 exhibits specificity in hydrolyzing different PLs in pulmonary surfactant and that the presence of hydrophilic surfactant protein A (SP-A) alters sPLA2-mediated hydrolysis. This report tests the hypothesis that hydrophobic SP-B also inhibits sPLA2-mediated surfactant hydrolysis. Three surfactant preparations were used containing varied amounts of SP-B and radiolabeled tracers of phosphatidylcholine (PC) or phosphatidylglycerol (PG): 1) washed ovine surfactant (OS) (pre- and postorganic extraction) compared with Survanta (protein poor), 2) Survanta supplemented with purified bovine SP-B (1–5%, wt/wt), and 3) a mixture of dipalmitoylphosphatidylcholine (DPPC), 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), and 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) (DPPC:POPC:POPG, 40:40:20) prepared as vesicles and monomolecular films in the presence or absence of SP-B. Hydrolysis of PG and PC by Group IB sPLA2 (PLA2G1A) was significantly lower in the extracted OS, which contains SP-B, compared with Survanta ( P = 0.005), which is SP-B poor. Hydrolysis of PG and PC in nonextracted OS, which contains all SPs, was lower than both Survanta and extracted OS. When Survanta was supplemented with 1% SP-B, PG and PC hydrolysis by PLA2G1B was significantly lower ( P < 0.001) than in Survanta alone. When supplemented into pure lipid vesicles and monomolecular films composed of PG and PC mixtures, SP-B also inhibited hydrolysis by both PLA2G1B and Group IIA sPLA2 (PLA2G2A). In films, PLA2G1B hydrolyzed surfactant PL monolayers at surface pressures ≤30 mN/m ( P < 0.01), and SP-B lowered the surface pressure range at which hydrolysis can occur. These results suggest the hydrophobic SP, SP-B, protects alveolar surfactant PL from hydrolysis mediated by multiple sPLA2 in both vesicles (alveolar subphase) and monomolecular films (air-liquid interface).

scholarly journals Lectin activity of the major surfactant protein (SP-A) may participate in, but is not required for, binding to rat type II cells.

1992 ◽  
Vol 40 (5) ◽  
pp. 643-649 ◽  
Author(s):  
T Thorkelsson ◽  
G M Ciraolo ◽  
G F Ross ◽  
J A Whitsett ◽  
R E Morris
Keyword(s):  
Protein A ◽  
Complex Mixture ◽  
Surfactant Protein ◽  
Structural Features ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lectin Activity ◽  
Type Ii Cell

Pulmonary surfactant is a complex mixture of lipids and proteins, of which surfactant protein A (SP-A) is the most abundant glycoprotein. The SP-A molecule has several distinct structural features that include a lectin-like domain, sharing structural features with other mammalian lectins. We have tested the hypothesis that lectin activity of the SP-A molecule is required for the binding to its receptor on the surface of alveolar Type II cells. By using colloidal gold immunocytochemistry in conjunction with electron microscopy, we evaluated the ability of mannosylated proteins to inhibit canine SP-A binding to rat Type II cells in vitro. After preincubation of SP-A with the mannosylated protein horse-radish peroxidase (HRP), SP-A was incubated with isolated filter-grown Type II cells. HRP did not alter the binding of SP-A to the Type II cell surface. Evidence that SP-A did bind to HRP was shown by coincident observation of gold-labeled SP-A and HRP precipitates. These results provide visual evidence that the lectin activity associated with SP-A is not required for its binding to receptor on rat alveolar Type II epithelial cells.

Sign in / Sign up

Export Citation Format

Share Document