Dynamic surface activity of a fully synthetic phospholipase-resistant lipid/peptide lung surfactant.
BACKGROUND
This study examines the surface activity and resistance to phospholipase degradation of a fully-synthetic lung surfactant containing a novel diether phosphonolipid (DEPN-8) plus a 34 amino acid peptide (Mini-B) related to native surfactant protein (SP)-B. Activity studies used adsorption, pulsating bubble, and captive bubble methods to assess a range of surface behaviors, supplemented by molecular studies using Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD), and plasmon resonance. Calf lung surfactant extract (CLSE) was used as a positive control.


RESULTS
DEPN-8+1.5% (by wt.) Mini-B was fully resistant to degradation by phospholipase A(2) (PLA(2)) in vitro, while CLSE was severely degraded by this enzyme. Mini-B interacted with DEPN-8 at the molecular level based on FTIR spectroscopy, and had significant plasmon resonance binding affinity for DEPN-8. DEPN-8+1.5% Mini-B had greatly increased adsorption compared to DEPN-8 alone, but did not fully equal the very high adsorption of CLSE. In pulsating bubble studies at a low phospholipid concentration of 0.5 mg/ml, DEPN-8+1.5% Mini-B and CLSE both reached minimum surface tensions <1 mN/m after 10 min of cycling. DEPN-8 (2.5 mg/ml)+1.5% Mini-B and CLSE (2.5 mg/ml) also reached minimum surface tensions <1 mN/m at 10 min of pulsation in the presence of serum albumin (3 mg/ml) on the pulsating bubble. In captive bubble studies, DEPN-8+1.5% Mini-B and CLSE both generated minimum surface tensions <1 mN/m on 10 successive cycles of compression/expansion at quasi-static and dynamic rates.


CONCLUSIONS
These results show that DEPN-8 and 1.5% Mini-B form an interactive binary molecular mixture with very high surface activity and the ability to resist degradation by phospholipases in inflammatory lung injury. These characteristics are promising for the development of related fully-synthetic lipid/peptide exogenous surfactants for treating diseases of surfactant deficiency or dysfunction.
Walther
Frans J
FJ
Los Angeles Biomedical Research Institute, Harbor-University of California at Los Angeles Medical Center, Torrance, California, United States of America. fwalther@lumc.nl
Waring
Alan J
AJ
Hernandez-Juviel
Jose M
JM
Gordon
Larry M
LM
Schwan
Adrian L
AL
Jung
Chun-Ling
CL
Chang
Yusuo
Y
Wang
Zhengdong
Z
Notter
Robert H
RH
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D007249:Inflammation; D008055:Lipids / Q000737:chemistry; D008168:Lung / Q000473:pathology; D010455:Peptides / Q000737:chemistry*; D010740:Phospholipases / Q000737:chemistry*; D054467:Phospholipases A2 / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D011663:Pulmonary Surfactants / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D020349:Surface Plasmon Resonance; D013499:Surface Properties; D013500:Surface Tension
D008055:Lipids; D010455:Peptides; D010743:Phospholipids; D011663:Pulmonary Surfactants; D010740:Phospholipases; D054467:Phospholipases A2