Synthetic and natural surfactant differentially modulate inflammation after meconium aspiration

Meconium aspiration syndrome remains a relevant cause of neonatal respiratory failure and is associated with severe pulmonary changes including surfactant inactivation and pronounced inflammatory changes. The present study investigated the effect of two different surfactant preparations-recombinant surfactant protein C surfactant (rSP-C Surf) and natural bovine surfactant-on pulmonary gas exchange and inflammatory response.

Twenty-three newborn piglets were intubated, mechanically ventilated, received 5 ml/kg 20% sterile meconium for induction of lung injury, and were randomized thereafter for controls ( n=7), rSP-C Surf ( n=8), or natural surfactant ( n=8). Surfactants were given as an intratracheal bolus (75 mg/kg) and animals were further ventilated.

Lung function variables, arterial blood gas samples and lung tissues were obtained. Histological evaluation was performed in right lung tissue using an established score. Cytokine mRNA expression (left lung tissue) was quantified using TaqMan real-time PCR (DeltaDeltaCT method, normalized to controls). In addition to significant improvement in gas exchange and lung function, histological evaluation showed significantly lower sum scores in the rSP-C Surf group than in controls). Cytokine mRNA expression of IL-1beta in whole lung tissue was significantly lower after administration of rSP-C Surf than in natural surfactant and controls whereas IL-10 mRNA expression was significantly induced in both surfactant groups.

Surfactant administration improved both gas exchange and pulmonary inflammatory cytokine transcription. Mechanisms underlying the differential inflammatory response in both surfactant preparations need to be further addressed.