Neuroimmune regulation of ventilator-induced lung injury.
BACKGROUND
Ventilator-induced lung injury (VILI) contributes to the mortality in patients with acute lung injury by increasing inflammation. Recent evidence suggests that stimulation of the cholinergic antiinflammatory pathway may be an attractive way to attenuate inflammatory injury.


OBJECTIVE
To determine the role of vagus nerve signaling in VILI and establish whether stimulation of the vagus reflex can mitigate VILI.


METHODS
We performed bilateral vagotomy in a mouse model of high-tidal volume-induced lung injury. We performed pharmacological and electrical vagus nerve stimulation in a rat model of VILI following ischemia/reperfusion injury. To determine the contribution of the alpha 7 acetylcholine nicotinic receptor to pulmonary cell injury, we exposed human bronchial epithelial cells to cyclic stretch in the presence of specific agonist or antagonist of the alpha 7 receptor.


RESULTS
Vagotomy exacerbates lung injury from VILI in mice as demonstrated by increased wet-to-dry ratio, infiltration of neutrophils, and increased IL-6. Vagal stimulation attenuates lung injury in rats after ischemia/reperfusion injury ventilated with high-volume strategies. Treatment of both mice and rats with the vagus mimetic drug semapimod resulted in decreased lung injury. Vagotomy also increased pulmonary apoptosis, whereas vagus stimulation (electrical and pharmacological) attenuated VILI-induced apoptosis. In vitro studies suggest that vagus-dependent effects on inflammation and apoptosis are mediated via the α7 nicotinc acetylcholine receptor-dependent effects on cyclic stretch-dependent signaling pathways c-jun N-terminal kinase and tumor necrosis factor receptor superfamily, member 6.


CONCLUSIONS
Stimulation of the cholinergic antiinflammatory reflex may represent a promising alternative for the treatment of VILI.
dos Santos
Claudia C dos
CC
Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada. dossantosc@smh.ca
Shan
Yuexin
Y
Akram
Ali
A
Slutsky
Arthur S
AS
Haitsma
Jack J
JJ
D055371:Acute Lung Injury / Q000209:etiology / Q000276:immunology; D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004558:Electric Stimulation; D006801:Humans; D006835:Hydrazones / Q000008:administration & dosage; D007166:Immunosuppressive Agents / Q000008:administration & dosage; D018836:Inflammation Mediators / Q000276:immunology; D015850:Interleukin-6 / Q000276:immunology; D008168:Lung / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015213:Neuroimmunomodulation / Q000276:immunology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000276:immunology; D015427:Reperfusion Injury; D014630:Vagus Nerve / Q000187:drug effects / Q000276:immunology; D055397:Ventilator-Induced Lung Injury / Q000150:complications / Q000276:immunology*; D000813:Anilides; D006146:Guanidines
D006835:Hydrazones; D007166:Immunosuppressive Agents; D018836:Inflammation Mediators; D015850:Interleukin-6; D011978:Receptors, Nicotinic; C097256:semapimod; D000813:Anilides; D006146:Guanidines