Design of Surfactant Protein B Peptide Mimics Based on the Saposin Fold for Synthetic Lung Surfactants

Surfactant protein (SP)-B is a 79-residue polypeptide crucial for the biophysical and physiological function of endogenous lung surfactant. SP-B is a member of the saposin or saposin-like proteins (SAPLIP) family of proteins that share an overall three-dimensional folding pattern based on secondary structures and disulfide connectivity and exhibit a wide diversity of biological functions. Here, we review the synthesis, molecular biophysics and activity of synthetic analogs of saposin proteins designed to mimic those interactions of the parent proteins with lipids that enhance interfacial activity. Saposin proteins generally interact with target lipids as either monomers or multimers via well-defined amphipathic helices, flexible hinge domains, and insertion sequences. Based on the known 3D-structural motif for the saposin family, we show how bioengineering techniques may be used to develop minimal peptide constructs that maintain desirable structural properties and activities in biomedical applications. One important application is the molecular design, synthesis and activity of Saposin mimics based on the SP-B structure. Synthetic lung surfactants containing active SP-B analogs may be potentially useful in treating diseases of surfactant deficiency or dysfunction including the neonatal respiratory distress syndrome and acute lung injury/acute respiratory distress syndrome.

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Flow-immunofluorescent studies of lung surfactant protein (SP-B)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100085575 ◽

1991 ◽

Vol 49 ◽

pp. 254-255

Author(s):

M. L. Longo

Keyword(s):

Respiratory Distress Syndrome ◽

Lipid Bilayer ◽

Distress Syndrome ◽

Lung Surfactant ◽

Surfactant Protein ◽

Flow Chamber ◽

Lung Surfactants ◽

Amphipathic Peptides ◽

Life Threatening ◽

Lung Surfactant Protein

Respiratory distress syndrome (RDS), a life threatening disorder, occurs if a lipid-protein complex which lines the airspaces of the lungs is compromised. Successful treatment of RDS has been reported with a vesicular dispersion containing dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylglycerol (egg PG), palmitic acid and lung surfactant protein, SP-B. It has been hypothesized that amphipathic regions of SP-B are important in these synthetic lung surfactants as they serve as a point of insertion for the protein into the lipid bilayer. Therefore two amphipathic peptides, SP-B(l-25) and SP-B(49-66), were synthesized to use in reconstitution studies. The incorporation of SP-B(l-25) into lipid bilayer has been visualized using immunofluorescent tagging in a specially designed flow-chamber.

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Chorioamnionitis alters lung surfactant lipidome in newborns with respiratory distress syndrome

Pediatric Research ◽

10.1038/s41390-021-01371-3 ◽

2021 ◽

Author(s):

Sonia Giambelluca ◽

Giovanna Verlato ◽

Manuela Simonato ◽

Luca Vedovelli ◽

Luca Bonadies ◽

...

Keyword(s):

Respiratory Distress Syndrome ◽

Respiratory Distress ◽

Distress Syndrome ◽

Lung Surfactant

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Annexin A2 Mediates Mycoplasma pneumoniae Community-Acquired Respiratory Distress Syndrome Toxin Binding to Eukaryotic Cells

mBio ◽

10.1128/mbio.01497-14 ◽

2014 ◽

Vol 5 (4) ◽

Cited By ~ 15

Author(s):

Sudha R. Somarajan ◽

Fadi Al-Asadi ◽

Kumaraguruparan Ramasamy ◽

Lavanya Pandranki ◽

Joel B. Baseman ◽

...

Keyword(s):

Respiratory Distress Syndrome ◽

Respiratory Distress ◽

Mammalian Cells ◽

Distress Syndrome ◽

Protein A ◽

A549 Cells ◽

Surfactant Protein ◽

Annexin A2 ◽

Toxin Binding ◽

Cards Toxin

ABSTRACT Mycoplasma pneumoniae synthesizes a novel human surfactant protein A (SP-A)-binding cytotoxin, designated community-acquired respiratory distress syndrome (CARDS) toxin, that exhibits ADP-ribosylating and vacuolating activities in mammalian cells and is directly linked to a range of acute and chronic airway diseases, including asthma. In our attempt to detect additional CARDS toxin-binding proteins, we subjected the membrane fraction of human A549 airway cells to affinity chromatography using recombinant CARDS toxin as bait. A 36-kDa A549 cell membrane protein bound to CARDS toxin and was identified by time of flight (TOF) mass spectroscopy as annexin A2 (AnxA2) and verified by immunoblotting with anti-AnxA2 monoclonal antibody. Dose-dependent binding of CARDS toxin to recombinant AnxA2 reinforced the specificity of the interaction, and further studies revealed that the carboxy terminus of CARDS toxin mediated binding to AnxA2. In addition, pretreatment of viable A549 cells with anti-AnxA2 monoclonal antibody or AnxA2 small interfering RNA (siRNA) reduced toxin binding and internalization. Immunofluorescence analysis of CARDS toxin-treated A549 cells demonstrated the colocalization of CARDS toxin with cell surface-associated AnxA2 upon initial binding and with intracellular AnxA2 following toxin internalization. HepG2 cells, which express low levels of AnxA2, were transfected with a plasmid expressing AnxA2 protein, resulting in enhanced binding of CARDS toxin and increased vacuolization. In addition, NCI-H441 cells, which express both AnxA2 and SP-A, upon AnxA2 siRNA transfection, showed decreased binding and subsequent vacuolization. These results indicate that CARDS toxin recognizes AnxA2 as a functional receptor, leading to CARDS toxin-induced changes in mammalian cells. IMPORTANCE Host cell susceptibility to bacterial toxins is usually determined by the presence and abundance of appropriate receptors, which provides a molecular basis for toxin target cell specificities. To perform its ADP-ribosylating and vacuolating activities, community-acquired respiratory distress syndrome (CARDS) toxin must bind to host cell surfaces via receptor-mediated events in order to be internalized and trafficked effectively. Earlier, we reported the binding of CARDS toxin to surfactant protein A (SP-A), and here we show how CARDS toxin uses an alternative receptor to execute its pathogenic properties. CARDS toxin binds selectively to annexin A2 (AnxA2), which exists both on the cell surface and intracellularly. Since AnxA2 regulates membrane dynamics at early stages of endocytosis and trafficking, it serves as a distinct receptor for CARDS toxin binding and internalization and enhances CARDS toxin-induced vacuolization in mammalian cells.

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Surfactant protein A and saturated phosphatidylcholine in respiratory distress syndrome.

American Journal of Respiratory and Critical Care Medicine ◽

10.1164/ajrccm.150.6.7952631 ◽

1994 ◽

Vol 150 (6) ◽

pp. 1672-1677 ◽

Cited By ~ 21

Author(s):

F R Moya ◽

H F Montes ◽

V L Thomas ◽

A M Mouzinho ◽

J F Smith ◽

...

Keyword(s):

Respiratory Distress Syndrome ◽

Respiratory Distress ◽

Distress Syndrome ◽

Protein A ◽

Surfactant Protein ◽

Surfactant Protein A

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Double-Blind, Randomized Trial of a Calf Lung Surfactant Extract Administered at Birth to Very Premature Infants for Prevention of Respiratory Distress Syndrome

PEDIATRICS ◽

10.1542/peds.76.4.593 ◽

1985 ◽

Vol 76 (4) ◽

pp. 593-599 ◽

Cited By ~ 4

Author(s):

Donald L. Shapiro ◽

Robert H. Notter ◽

Frederick C. Morin ◽

Karl S. Deluga ◽

Leonard M. Golub ◽

...

Keyword(s):

Respiratory Distress Syndrome ◽

Respiratory Distress ◽

Premature Infants ◽

Neonatal Intensive Care ◽

Distress Syndrome ◽

Lung Surfactant ◽

Treated Group ◽

Control Group ◽

Double Blind ◽

Severe Respiratory Distress

Organic solvent extraction of surfactant obtained by lavage of calf lungs yields a highly surfaceactive material. A double blind, randomized clinical trial to determine the effect of this material on respiratory distress syndrome in premature infants was initiated in the Neonatal Intensive Care Unit at the University of Rochester in December 1983. Infants 25 to 29 weeks gestational age were eligible for entry into the trial. At the time of this interim analysis 32 patients had been randomly selected and entered into the trial, 16 surfactant-treated patients and 16 in a control group who received only saline. At birth, intrapulmonary instillation of the calf lung surfactant extract dispersed in saline or saline alone occurred in the delivery room immediately after intubation and prior to ventilation; infants were then ventilated and treated as usual. At 6, 12, 24, 48, and 72 hours after birth, the severity of respiratory distress was categorized as either minimal, intermediate, or severe based on oxygen and mean airway pressure requirements. Differences observed at six hours after birth were of marginal significance, but at 12 and 24 hours the surfactant-treated group had significantly (P < .01) less severe respiratory distress compared with the control group. Differences between treated and control infants were not statistically significant at 48 and 72 hours after birth. In four surfactant-treated infants the severity of respiratory distress worsened between 24 and 48 hours after birth, suggesting that one dose of surfactant at birth may not be sufficient for some infants.

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