Synthetic lung surfactants containing SP-B and SP-C peptides plus novel phospholipase-resistant lipids or glycerophospholipids (original) (raw)
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Dynamic Surface Activity of a Fully Synthetic Phospholipase-Resistant Lipid/Peptide Lung Surfactant
PLoS ONE, 2007
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.
Proceedings of the National Academy of Sciences, 1990
We have synthesized pulmonary surfactant apoprotein SP-B peptides by solid-phase chemistry and demonstrated their ability to enhance the surface-active properties of synthetic lipid mixtures. The synthetic peptides were reactive with antiserum generated against the native bovine surfactant peptide. Both peptides conferred surfactant-like properties to synthetic lipid mixtures as assessed by a Wilhelmy balance and pulsating bubble surfactometer. Likewise, mixtures of synthetic SP-B peptides and lipid restored compliance of isolated surfactant-deficient rat lungs. This work demonstrates the utility of SP-B as a functional component of pulmonary surfactant mixtures for treatment of respiratory distress syndrome or other disorders characterized by surfactant deficiency.
Interaction of Lung Surfactant Proteins with Anionic Phospholipids
Biophysical Journal, 2001
Langmuir isotherms, fluorescence microscopy, and atomic force microscopy were used to study lung surfactant specific proteins SP-B and SP-C in monolayers of dipalmitoylphosphatidylglycerol (DPPG) and palmitoyloleoylphosphatidylglycerol (POPG), which are representative of the anionic lipids in native and replacement lung surfactants. Both SP-B and SP-C eliminate squeeze-out of POPG from mixed DPPG/POPG monolayers by inducing a two-to three-dimensional transformation of the fluid-phase fraction of the monolayer. SP-B induces a reversible folding transition at monolayer collapse, allowing all components of surfactant to remain at the interface during respreading. The folds remain attached to the monolayer, are identical in composition and morphology to the unfolded monolayer, and are reincorporated reversibly into the monolayer upon expansion. In the absence of SP-B or SP-C, the unsaturated lipids are irreversibly lost at high surface pressures. These morphological transitions are identical to those in other lipid mixtures and hence appear to be independent of the detailed lipid composition of the monolayer. Instead they depend on the more general phenomena of coexistence between a liquid-expanded and liquid-condensed phase. These three-dimensional monolayer transitions reconcile how lung surfactant can achieve both low surface tensions upon compression and rapid respreading upon expansion and may have important implications toward the optimal design of replacement surfactants. The overlap of function between SP-B and SP-C helps explain why replacement surfactants lacking in one or the other proteins often have beneficial effects.
Peptide-based synthetic pulmonary surfactant for the treatment of respiratory distress disorders
Current Opinion in Chemical Biology, 2016
KL 4 (Sinapultide) represents the first peptide-based replacement for surfactant protein B in pulmonary surfactant (PS) therapies approved for clinical use. Surfaxin, its formulation with PS lipids, shows the promise of synthetic PS for replacing animal-derived PS in the treatment of respiratory distress syndromes and for treating acute lung injury. Efforts to characterize the molecular basis for KL 4 function have revealed the peptide exhibits a helical structure which differentially partitions in response to both lipid saturation levels and pH. The penta-residue repeat of KL 4 leads to adaptive peptide helicity, varying with partitioning depth, and suggests structural plasticity may represent an important mechanism for differential trafficking of lipids, particularly in intra-alveolar surfactant for the formation of stable DPPC monolayers at air-water interfaces.
Pediatric Research, 1988
C were isolated from lavage fluids of bovine lungs and recombined (lipid/proteins, 911, wt/wt) with dipalmitoyl phosphatidylcholine for testing in vitro and in surfactantdeficient adult rats. Using a pulsating bubble surfactometer, we found that inflation pressures of bubbles at minimum radii in these mixtures were 0.34 f 0.05 cm H 2 0 (+ SD, n = 24) after 1 min. These values were not affected by increasing amounts of surfactant protein relative to dipalmitoyl phosphatidylcholine (DPPC). Minimum inflation pressures were similar to those of modified bovine surfactant, surfactant Tokyo Akita (TA) (0.33 f 0.05 cm H20, n = 7). I n vivo testing was carried out in adult rats made surfactant deficient by repeated lavage and ventilated with 100% oxygen. Rats received tracheal instillations of either air, DPPC, DPPCISP-B,C (9:1), or surfactant TA at 50 mg/kg body weight. Surfactant TA and DPPCISP-B, SP-C mixtures resulted in similar immediate and sustained improvements in arterial oxygenation (308 + 66 torr, n = 10 and 312 2 101 torr, n = 6 at 30 min posttreatment) that were significantly greater than those of sham (76 f 24 torr, n = 17) and DPPC-treated rats (64 f 32 torr, n = 7). Rats treated with either DPPC/SP-B,C mixtures or surfactant TA showed similar postmortem static lung compliances (2.3 f 0.8 ml/cm H20/kg, n = 8 and 1.9 2 0.4 ml/cm H20/kg, n = 5, respectively) that were significantly larger than sham (1.3 + 0.3 ml/cm H 2 0 / kg, n = 14) and DPPC-treated rats (1.2 f 0.2 ml/cm H20/ kg, n = 6). We conclude that simple mixtures of DPPC and SP-B,C duplicate results found with more complex mixtures of pulmonary surfactants.
Colloids and Surfaces B: …, 2007
An important aspect of developing a functional, biomimetic lung surfactant (LS) replacement is the selection of the synthetic lipid and surfactant protein (SP) mimic components. Studies elucidating the roles of different lipids and surfactant proteins in natural LS have provided critical information necessary for the development of synthetic LS replacements that offer performance comparable to the natural material. In this study, the in vitro surface-active behaviors of peptide-and peptoid-based mimics of the lung surfactant proteins, SP-B and SP-C, were investigated using three different lipid formulations. The lipid mixtures were chosen from among those commonly used for the testing and characterization of SP mimics: (1) dipalmitoyl phosphatidylcholine : palmitoyloleoyl phosphatidylglycerol 7:3 [w/w] (PCPG), (2) dipalmitoyl phosphatidylcholine : palmitoyloleoyl phosphatidylglycerol : palmitic acid 68:22:9 [w/w] (TL), and (3) dipalmitoyl phosphatidylcholine : palmitoyloleoyl phosphatidylcholine : palmitoyloleoyl phosphatidylglycerol : palmitoyloleoyl phosphatidylethanolamine : palmitoyloleoyl phosphatidylserine : cholesterol, 16:10:3:1:3:2 [w/w] (IL). The lipid mixtures and lipid/peptide or lipid/peptoid formulations were characterized in vitro using a Langmuir-Wilhelmy surface balance, fluorescent microscopic imaging of surface film morphology, and a pulsating bubble surfactometer. Results show that the three lipid formulations exhibit significantly different surface-active behaviors, both in the presence and absence of SP-mimics, with desirable in vitro biomimetic behaviors being greatest for the TL formulation. Additionally, lipid composition greatly affects the extent of biomimicry in the surface-active behaviors of both peptoid-and peptide-based SP mimics.
Surfactant Protein B and C Analogues
Molecular Genetics and Metabolism, 2000
Mammalian lung surfactant is a mixture of phospholipids and four surfactant-associated proteins (SP-A, SP-B, SP-C, and SP-D). Its major function is to reduce surface tension at the air-water interface in the terminal airways by the formation of a surface-active film highly enriched in dipalmitoyl phosphatidylcholine (DPPC), thereby preventing alveolar collapse during expiration. SPA and SP-D are large hydrophilic proteins, which play an important role in host defense, whereas the small hydrophobic peptides SP-B and SP-C interact with DPPC to generate and maintain a surface-active film. Surfactant replacement therapy with bovine and porcine lung surfactant extracts, which contain only polar lipids and SP-B and SP-C, has revolutionized the clinical management of premature infants with respiratory distress syndrome. Newer surfactant preparations will probably be based on SP-B and SP-C, produced by recombinant technology or peptide synthesis, and reconstituted with selected synthetic lipids. The development of peptide analogues of SP-B and SP-C offers the possibility to study their molecular mechanism of action and will allow the design of surfactant formulations for specific pulmonary diseases and better quality control. This review describes the hydrophobic peptide analogues developed thus far and their potential for use in a new generation of synthetic surfactant preparations.
Lipid composition greatly affects the in vitro surface activity of lung surfactant protein mimics
Colloids and Surfaces B: Biointerfaces, 2007
A crucial aspect of developing a functional, biomimetic lung surfactant (LS) replacement is the selection of the synthetic lipid mixture and surfactant proteins (SPs) or suitable mimics thereof. Studies elucidating the roles of different lipids and surfactant proteins in natural LS have provided critical information necessary for the development of synthetic LS replacements that offer performance comparable to the natural material. In this study, the in vitro surface-active behaviors of peptide-and peptoid-based mimics of the lung surfactant proteins, SP-B and SP-C, were investigated using three different lipid formulations. The lipid mixtures were chosen from among those commonly used for the testing and characterization of SP mimics-(1) dipalmitoyl phosphatidylcholine:palmitoyloleoyl phosphatidylglycerol 7:3 (w/w) (PCPG), (2) dipalmitoyl phosphatidylcholine:palmitoyloleoyl phosphatidylglycerol:palmitic acid 68:22:9 (w/w) (TL), and (3) dipalmitoyl phosphatidylcholine:palmitoyloleoyl phosphatidylcholine:palmitoyloleoyl phosphatidylglycerol:palmitoyloleoyl phosphatidylethanolamine:palmitoyloleoyl phosphatidylserine:cholesterol 16:10:3:1:3:2 (w/w) (IL). The lipid mixtures and lipid/peptide or lipid/peptoid formulations were characterized in vitro using a Langmuir-Wilhelmy surface balance, fluorescent microscopic imaging of surface film morphology, and a pulsating bubble surfactometer. Results show that the three lipid formulations exhibit significantly different surface-active behaviors, both in the presence and absence of SP mimics, with desirable in vitro biomimetic behaviors being greatest for the TL formulation. Specifically, the TL formulation is able to reach low-surface tensions at physiological temperature as determined by dynamic PBS and LWSB studies, and dynamic PBS studies show this to occur with a minimal amount of compression, similar to natural LS.
SP-B refining of pulmonary surfactant phospholipid films
American Journal of Physiology-Lung Cellular and Molecular Physiology, 1999
Pulmonary surfactant stabilizes the alveoli by lining the air-fluid interface with films that reduce surface tension to near 0 mN/m (γmin). Surfactant protein B (SP-B) enhances the surface activity of surfactant phospholipids. A captive bubble tensiometer (CBT) was used to study the properties of adsorbed films of dipalmitoylphosphatidylcholine (DPPC) with acidic 1-palmitoyl-2-oleoyl- sn-glycero-3-[phospho- rac-(1-glycerol)] (POPG) or neutral 1-palmitoyl-2-oleoyl- sn-glycerol-3-phosphocholine with (7:3) and without 1% dimeric SP-B. SP-B enhanced the adsorption rate of DPPC-containing neutral or acidic lipid suspensions (1 mg/ml) to a similar extent. Quasi-static cycling of these films revealed that SP-B significantly decreased the film area reduction required to reach γminfor the acidic but not for the neutral system. The results obtained with DPPC-phosphatidylglycerol (PG)-SP-B were consistent with selective DPPC adsorption into the surface monolayer during film formation. Film are...