27 Activity of Elastase and α¹-proteinase inhibitor in bronchial secretions of premature infants suffering from severe respiratory distress syndrome (RDS) treated with a natural porcine Surfactant (Curosurf)

Abstract

Proteolytic enzymes, especially elastase (E) released from neutrophils, seem to play a role in the pathogenesis of bronchopulmonary dysplasia (BPD). In some trials the combined incidence of death and BPD was shown to be reduced after surfactant replacement therapy in severe RDS.

In a prospective study we have analyzed activities and concentrations of free elastase (E), α₁-proteinase inhibitor (α₁,-PI) and the enzyme inhibitor complex (E-α₁-PI) in bronchial secretions of 52 premature infants suffering from severe RDS following surfactant replacement therapy. Within a randomized trial “single versus multiple doses of surfactant (Curosurf)” the enzyme inhibitor potential of patients with severe RDS was analyzed during the first 10 days of life.

Results in 28/52 infants free elastase (E) was found in bronchial secretions (concentrations 0,8 - 162 μg/mg albumin). In these patients no free activity of α₁-PI could be detected, however, E α₁-PI was identical in all patients. Elastase was present especially in bronchial secretions of immature and Low birth weight infants. 21/28 infants in whom free elastase was detected had an gestational age <30 weeks. No differences in concentrations of free elastase were found between premature infants who received a single dose and those who received 3 subsequent doses of surfactant.

Conclusions In all 52 cases the enzyme inhibitor complex <E α₁-PI) could be demonstrated. The was no correlation between the concentration of E α₁-PI and the activity of free elastase. Multiple treatment did not influence the imbalance between the activity of the enzyme and activity of α₁-PI. Ue need sore knowlegde about factors that might influence the influx of neutrophils and the consecutive release of elastase into the bronchoalveolar space.

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