Influence of bilirubin on surface tension properties of lung surfactant.

Abstract

Aim-To investigate the influence of bilirubin on the surface tension activity of a porcine derived (Curosurf) and synthetic (Exosurf) surfactant.Methods-The captive bubble surfactometer at phospholipid doses of 0.5 mg/ml (low dose) and 1 mg/ml (high dose) in solutions of increasing bilirubin concentrations (0.25, 0.5, and 1.0 mg/ml) was used.Results-Curosurf (without bilirubin) showed a higher surface tension activity than Exosurf, as shown by area compression of 30 (SD 0.6)% compared with 76(1.4)% at low surfactant dose and 25 (0.9)% compared with 85 (0.5)% at high dose (P<0.01). Bilirubin showed negligible surface activity at the concentrations studied. At low phospholipid dose (0.5 mglml Curosurf), bilirubin increased film area compression of lipid extract surfactant from 30 (0.6)% to 55 (1.6)%, 59 (0.1)%, and 68 (0.5)% at the three studied bilirubin concentrations, respectively (P<0.01). At high phospholipid dose (1 mg/ml Curosurf), bilirubin had the same adverse, although less pronounced, effect on film area compression of porcine lipid extract surfactant (25 (0.9)% vs 26 (0.9)%, 39 (1.3)%, and 44 (1.1)%, respectively) (P<0.01). Using synthetic surfactant (Exosurf), with a much lower original surface activity, bilirubin did not further inhibit its surface tension properties at any of the phospholipid doses studied. Conclusion-These results indicate that in vitro bilirubin impairs the surface tension activity ofporcine lipid extract surfactant, but does not affect synthetic surfactant activity. (Arch Dis Child 1996;75:F191-F196)

Bilirubin influence on oxidative lung damage and surfactant surface tension properties

“…17 The different effect of bilirubin on natural and synthetic surfactant was attributed to the different composition of the two surfactants: it is possible that tyloxapol, an alcohol that is contained in the synthetic surfactant, can ''neutralize'' the adverse effect of bilirubin, but the most attractive hypothesis is that bilirubin can interact with the surfactant proteins SP-B or SP-C, which are absent in synthetic surfactant. Thus, our in vivo results, which confirm the observations of Amato et al, 16,17 might have practical implications for the management of jaundiced infants affected by respiratory distress syndrome requiring exogenous surfactant treatment. It is possible that more intense treatment of hyperbilirubinemia, or a more aggressive treatment with exogenous surfactant, may be useful in the treatment of jaundiced infants with respiratory distress syndrome.…”

“…Thus, in our model of lung injury, the increase of bilirubin plasma level induces the appearance of bilirubin in bronchoalveolar fluid, which in turn causes a partial inhibition of surfactant property of lowering surface tension. This is the first in vivo observation of the detrimental effect of bilirubin on surfactant surface activity, although similar findings were described in vitro by Amato et al 16,17 They demonstrated that bilirubin impairs the surface tension activity of porcine lipid extract surfactant but does not affect synthetic surfactant activity, 16 and that this effect occurs independent of pH. 17 The different effect of bilirubin on natural and synthetic surfactant was attributed to the different composition of the two surfactants: it is possible that tyloxapol, an alcohol that is contained in the synthetic surfactant, can ''neutralize'' the adverse effect of bilirubin, but the most attractive hypothesis is that bilirubin can interact with the surfactant proteins SP-B or SP-C, which are absent in synthetic surfactant.…”

“…5 In fact, although its role in vivo has not been definitively clarified in infants, 6-10 the antioxidant effect of bilirubin as a scavenger of reactive species of oxygen was well-documented in vitro [11][12][13][14] as well as in animal studies. 15 Moreover, bilirubin was demonstrated to impair the surface tension of natural lung surfactant in vitro, 16 its effect being independent of pH.…”

Comparison of Pulmonary and Inflammatory Effects of Lipid- and Water-Soluble Components in Meconium in Newborn Piglets

“…Amato et al [32] observed that bilirubin impaired surfactant activity, without affecting synthetic surfactant activity. Furthermore, Moses et al [9] found in vitro substances interfering with surfactant function in both the water-and lipid-soluble subfractions of meconium.…”

Thrombomodulin serum levels in ventilated preterm babies with respiratory distress syndrome

“…A number of factors determine¯uid balance in the lung such as transmural hydrostatic and protein osmotic pressure, vascular surface area and vascular endothelial barrier permeability. An increase in lung microvascular permeability due to epithelial/endothelial damage, such as in patients with RDS, will promote¯uid¯ux into the lung and cause surfactant inhibition by leaked plasma proteins [1,3].…”