5-Lipoxygenase deficiency prevents respiratory failure during ventilator-induced lung injury.
BACKGROUND
Mechanical ventilation with high VT (HVT) progressively leads to lung injury and decreased efficiency of gas exchange. Hypoxic pulmonary vasoconstriction (HPV) directs blood flow to well-ventilated lung regions, preserving systemic oxygenation during pulmonary injury. Recent experimental studies have revealed an important role for leukotriene (LT) biosynthesis by 5-lipoxygenase (5LO) in the impairment of HPV by endotoxin.


OBJECTIVE
To investigate whether or not impairment of HPV contributes to the hypoxemia associated with HVT and to evaluate the role of LTs in ventilator-induced lung injury.


METHODS
We studied wild-type and 5LO-deficient mice ventilated for up to 10 hours with low VT (LVT) or HVT.


RESULTS
In wild-type mice, HVT, but not LVT, increased pulmonary vascular permeability and edema formation, impaired systemic oxygenation, and reduced survival. HPV, as reflected by the increase in left pulmonary vascular resistance induced by left mainstem bronchus occlusion, was markedly impaired in animals ventilated with HVT. HVT ventilation increased bronchoalveolar lavage levels of LTs and neutrophils. In 5LO-deficient mice, the HVT-induced increase of pulmonary vascular permeability and worsening of respiratory mechanics were markedly attenuated, systemic oxygenation was preserved, and survival increased. Moreover, in 5LO-deficient mice, HVT ventilation did not impair the ability of left mainstem bronchus occlusion to increase left pulmonary vascular resistance. Administration of MK886, a 5LO-activity inhibitor, or MK571, a selective cysteinyl-LT(1) receptor antagonist, largely prevented ventilator-induced lung injury.


CONCLUSIONS
These results indicate that LTs play a central role in the lung injury and impaired oxygenation induced by HVT ventilation.
Caironi
Pietro
P
Department of Anesthesia and Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, 02114, USA.
Ichinose
Fumito
F
Liu
Rong
R
Jones
Rosemary C
RC
Bloch
Kenneth D
KD
Zapol
Warren M
WM
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000172:deficiency*; D015289:Leukotrienes / Q000096:biosynthesis; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D011652:Pulmonary Circulation; D012128:Respiratory Distress Syndrome / Q000201:enzymology / Q000209:etiology*; D012131:Respiratory Insufficiency / Q000201:enzymology / Q000517:prevention & control*; D014661:Vasoconstriction; D012122:Ventilators, Mechanical / Q000009:adverse effects*
D015289:Leukotrienes; D001094:Arachidonate 5-Lipoxygenase