Aspiration-induced lung injury: role of complement.
OBJECTIVE
To examine the role of complement in the development of acid aspiration-induced lung injury in the rat. It was postulated that inhibition or depletion of complement attenuates aspiration-induced lung injury.


METHODS
Controlled animal trial.


METHODS
Animal Laboratory, Jefferson Medical College, Philadelphia, PA.


METHODS
Anesthetized rats.


METHODS
Aspiration was induced by the intratracheal administration of 0.2 mL of 0.1 N hydrochloric acid (n = 7) and lung injury was evaluated by determining water content, myeloperoxidase activity, protein concentration, and leukocyte count in bronchoalveolar lavage fluid. Muscle PO2 was directly measured using a thin-film chamber oxygen sensor and serum tumor necrosis factor-alpha was assayed by enzyme-linked immunosorbent assay. The effect of complement inhibition by recombinant human soluble complement receptor type 1 (n = 8) or complement depletion by cobra venom factor (n = 7) on lung injury was evaluated.


RESULTS
Acid aspiration induced pulmonary leukosequestration, edema, and a microvascular permeability defect, along with tissue hypoxia. Pretreatment with soluble complement receptor type 1 (complement inhibition) or cobra venom factor (complement depletion) significantly reduced lung edema (-61 +/- 7%; p < .05), eliminated protein accumulation in bronchoalveolar lavage fluid (p < .01), and improved (p < .05) tissue oxygenation. In contrast, there was no effect of soluble complement receptor type 1 or of cobra venom factor on leukosequestration.


CONCLUSIONS
Acid aspiration induces lung injury through a complement-dependent mechanism that leads to microvascular permeability defects. Therefore, the possibility that complement inhibitors may have a salutary effect in humans with aspiration-induced lung injury should be investigated.
Rabinovici
R
R
Department of Surgery, Jefferson Medical College, Philadelphia, PA 19107-5083, USA.
Neville
L F
LF
Abdullah
F
F
Phillip
D R
DR
Vernick
J
J
Fong
K L
KL
Hillegas
L
L
Feuerstein
G
G
D000818:Animals; D002199:Capillary Permeability; D003167:Complement Activation / Q000187:drug effects*; D003165:Complement System Proteins / Q000502:physiology*; D004195:Disease Models, Animal; D004546:Elapid Venoms / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D006851:Hydrochloric Acid; D008297:Male; D011015:Pneumonia, Aspiration / Q000139:chemically induced / Q000188:drug therapy / Q000276:immunology*; D011292:Premedication; D051381:Rats; D017207:Rats, Sprague-Dawley; D011951:Receptors, Complement / Q000502:physiology*; D011994:Recombinant Proteins
D004546:Elapid Venoms; D011951:Receptors, Complement; D011994:Recombinant Proteins; C016310:cobra venom factor; C082885:soluble complement inhibitor 1; D003165:Complement System Proteins; D006851:Hydrochloric Acid