Effects of Glucocorticoids on the microstructure of an exogenous pulmonary surfactant

CIMATO A.; HOYOS OBANDO A; ZURDO F; PIEHL L; FACORRO G; MARTINEZ SARRASAGUE M.

Sociedad Argentina de Biofísica

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biofísica (SAB 2014).; 2014

Introduction: Pulmonary surfactant would be used as a carrier of corticosteroids drugs in therapy for respiratory diseases. It is vital that corticosteroids delivered via the lungs not interfere with surface activity of the pulmonary surfactant lining layer. In our previous work we have found that cholesterol change surfactant structure and consequently altered its activity. As corticoids have a similar molecular structure, could be expected to have similar behavoir. We studied the effect of budesonide, beclametasone and fluticasone on structural properties of an exogenous pulmonary surfactant (EPS). Methods: Bovine EPS (PL=10mg/ml) added with each corticoid (1 mg/ml) was labeled with 5 or 16 -doxyl stearic acid. Order parameter S, correlation time, and S/W ratio, calculated fromElectron Spin Resonance (ESR) spectrawere used to evaluate the conformational and fluidity changes. EPS fractions were separated by centrifugation (12000rpm). The active/inactive subtype ratio was evaluated by PL determination. Corticoid incorporated into surfactant was evaluated by UV absorption. Surface tension was measure using a pulsating bubble surfactometer. Results: Budesonide, beclametasone and Cholesterol increased the order parameter. Fluticasone and betametasone increased the S/W ratio. Nor significantly changed were found in the correlation time neither in the active/inactive subtype ratio. All samples showed appropriate surfactant activity. Conclusions: we have demonstrated that glucocorticoids alter the structure of the bilayer on the polar region without altering surfactant activity. References María Martínez Sarrasague, et al. Respiratory Physiology & Neurobiology 189 (2013) 581.