Effect of exogenous surfactant therapy on levels of pulmonary surfactant proteins A and D in preterm infants with respiratory distress syndrome

Abstract

Objectives: To examine whether exogenous pulmonary surfactants (exPS) substitute for or merely supplement endogenous pulmonary surfactants (enPS) by looking at sequential changes in the surfactant proteins (SP) SP-A and SP-D in alveolar pools. Methods: Fourteen preterm infants with RDS treated with an artificial surfactant were compared to five normalterm infants without RDS who were treated with artificial ventilation at birth. Results: Immediately after birth, SP-A and SP-D were essentially absent in the alveolar pools of the RDS group, but were present at normal levels in the controls. Treatment with exPS apparently stimulated enPS production. Conclusions: In infants who responded well to exPS therapy, the SP concentration reached essentially normal levels within 48-72 h after birth.

Untapped Therapeutic Potential of Surfactant Proteins: Is There a Case for Recombinant SP-D Supplementation in Neonatal Lung Disease?

“…Exogenous surfactant treatment appears to promote endogenous surfactant production and by 48-72 h SP-A and SP-D levels approximate the levels present in term newborns [12] . However, a study by Beresford and Shaw [13] reported that low levels of SP-D (in contrast to SP-A and SP-B) in the first few days of life were associated with a higher risk of developing neonatal chronic lung disease (CLD), thus there could be a critical window soon after birth in which absence of SP-D sets in train an inflammatory reaction which disturbs surfactant homeostasis in those infants going on to develop CLD.…”

“…SP-D is a large, multimeric, hydrophilic protein that belongs to the collectin group of carbohydrate-binding proteins, named for their collagen-like domains combined with globular carbohydrate-binding (lectin) domains, other members of which in humans include SP-A, and mannan/mannose-binding lectin [12] . Collectins are calcium-dependent lectins and multimeric sharing a common subunit structure.…”

Surfactant protein A is decreased in the lung of rats with hepatopulmonary syndrome

“…It was previously demonstrated that SP-A increases in the blood circulation of patients with acute lung injury/acute respiratory distress syndrome [15][16][17] .…”

“…The absence or reduction of surfactant is associated with neonatal respiratory distress syndrome and congenital surfactant deficiency 15,16 . Conversely, there is an increase in pulmonary alveolar proteinosis, which is related to significant respiratory dysfunction.…”

“…Surfactant supplementation with SP-A and SP-D has been used as a therapy for lung disease in infancy and the inflammatory and immune protection benefits of this treatment have been proven [15][16][17] .…”