Surfactant protein A recruits neutrophils into the lungs of ventilated preterm lambs.
We tested the effects of surfactant protein A (SP-A) on inflammation and surfactant function in ventilated preterm lungs. Preterm lambs of 131 d gestation were ventilated for 15 min to initiate a mild inflammatory response, and were then treated with 100 mg/ kg recombinant human SP-C surfactant or with the same surfactant supplemented with 3 mg/kg ovine SP-A. Addition of SP-A to the SP-C surfactant did not change lung function. After 6 h of ventilation, cell numbers in the alveolar wash were 4.9 times higher in SP-A + SP-C-surfactant-treated animals. Cellular infiltrates consisted of neutrophils that produced less hydrogen peroxide than did cells from SP-C-surfactant-treated animals. Expression of adhesion molecules CD11b and CD44 was significantly greater after SP-A treatment, whereas the expression of CD14 was unchanged. Messenger RNAs (mRNAs) for the proinflammatory cytokines interleukin (IL)-1beta, IL-6, and IL-8, but not tumor necrosis factor-alpha, were increased in SP-A-treated lungs. Surfactant protein mRNAs and protein leakage into alveolar washes were not altered by SP-A, indicating that SP-A treatment produces no evidence of lung injury. The present study identifies an unanticipated role of SP-A in neutrophil recruitment in the lungs of preterm lambs.
Kramer
B W
BW
Department of Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
Jobe
A H
AH
Bachurski
C J
CJ
Ikegami
M
M
D000818:Animals; D000831:Animals, Newborn; D002634:Chemotaxis, Leukocyte / Q000502:physiology*; D005865:Gestational Age; D006023:Glycoproteins / Q000502:physiology*; D007249:Inflammation; D008168:Lung / Q000276:immunology; D009504:Neutrophils / Q000502:physiology*; D011510:Proteolipids / Q000502:physiology*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis / Q000502:physiology*; D012121:Respiration, Artificial; D012756:Sheep
D006023:Glycoproteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants