Interactions between plasma proteins and pulmonary surfactant: surface balance studies

Abstract

The influence of human fibrinogen, alpha-globulin, and albumin on the properties of monolayers of pulmonary surfactant under dynamic compression and expansion has been studied at 37 degrees C. Each of the proteins altered some of the properties of the normal compression and expansion isotherms of surfactant such that characteristics deemed desirable for proper lung function were impaired. The order of potency of these effects was fibrinogen greater than globulin greater than albumin. The proteins (a) decreased the maximum surface pressure (equivalent to the minimum surface tension) which the surfactant monolayers attained on compression, (b) decreased the areas occupied per mole of lipid phosphorus when the monolayers were at surface tensions of 20 and 12 mN.m-1, (c) reduced the areas of the hysteresis between compression and expansion isotherms, and (d) decreased the rate of change of surface tension with area at the point of initial expansion of the monolayers. The proteins might compete with surfactant lipid for available space at the interface, especially at low film compression. They might also enhance the desorption of lipid from the monolayer. The findings are consistent with the loss of pulmonary function and presence of edema that occur in adult respiratory distress syndrome being contributed to by plasma proteins interfering with surfactant function.

Function and inhibition sensitivity of the N-terminal segment of surfactant protein B (SP-B1-25) in preterm rabbits

“…Pulmonary surfactant is sensitive to functional inhibition by plasma proteins, which invade the alveolar space during acute lung injury 21-24. Among the plasma proteins, albumin,25-30 haemoglobin,31 C-reactive protein,32 and fibrinogen and fibrin monomers27 28 33 34 have proven surfactant inhibitory properties in vitro with the following rank order: fibrin monomer>fibrinogen> haemoglobin>albumin. Fresh frozen plasma was chosen for this study for its strong inhibiting effect.…”

Roles of γ-Globulin in the Dynamic Interfacial Behavior of Mixed Dipalmitoyl Phosphatidylcholine/γ-Globulin Monolayers at Air/Liquid Interfaces

“…Moreover, the comparatively insignificant collapse plateau also suggests that most of the DPPC molecules were removed before monolayer collapse. In a monolayer study of lung surfactant with plasma proteins, it has been suggested that as plasma proteins left the surface, they carried along surfactant lipids with them (24). Furthermore, in a mixed monolayer study of DPPC with SP-B and SP-C, it has been reported that the squeeze-out of the proteins appeared to be accompanied by the exclusion of DPPC at low compression rates (15).…”

“…When the cyclic compressionexpansion isotherms were carried up to very high surface pressures, DPPC collapsed and irreversibly left the interface (11). In addition, the hysteresis isotherms of mixed spread plasma protein/pig lung surfactant monolayers implied that the proteins may leave the interface and carry along surfactant lipids with them (24). Plasma proteins seemed to inhibit lung surfactant function by preventing the phospholipids from adsorbing to the interface, possibly by a competition between the plasma proteins and phospholipids for space at the interface rather than direct molecular interactions between proteins and phospholipids (13,24,25).…”

A Function of Lung Surfactant Protein SP-B

“…A deficiency of surfactant at birth, often due to premature delivery, is responsible for the development of neonatal respiratory distress syndrome (1,3). Inactivation of lung surfactant, perhaps as a result of pulmonary edema, is likely involved in the development of adult respiratory distress syndrome (4)(5)(6)(7). As a consequence of the serious morbidity and mortality of these syndromes, surfactant replacement therapy is being investigated by a number of research groups and is increasingly used in the treatment of premature infants (8).…”