Alveolar macrophages and Toll-like receptor 4 mediate ventilated lung ischemia reperfusion injury in mice.
BACKGROUND
Ischemia-reperfusion (I-R) injury is a sterile inflammatory process that is commonly associated with diverse clinical situations such as hemorrhage followed by resuscitation, transient embolic events, and organ transplantation. I-R injury can induce lung dysfunction whether the I-R occurs in the lung or in a remote organ. Recently, evidence has emerged that receptors and pathways of the innate immune system are involved in recognizing sterile inflammation and overlap considerably with those involved in the recognition of and response to pathogens.


METHODS
The authors used a mouse surgical model of transient unilateral left pulmonary artery occlusion without bronchial involvement to create ventilated lung I-R injury. In addition, they mimicked nutritional I-R injury in vitro by transiently depriving cells of all nutrients.


RESULTS
Compared with sham-operated mice, mice subjected to ventilated lung I-R injury had up-regulated lung expression of inflammatory mediator messenger RNA for interleukin-1β, interleukin-6, and chemokine (C-X-C motif) ligand-1 and -2, paralleled by histologic evidence of lung neutrophil recruitment and increased plasma concentrations of interleukin-1β, interleukin-6, and high-mobility group protein B1 proteins. This inflammatory response to I-R required toll-like receptor-4 (TLR4). In addition, the authors demonstrated in vitro cooperativity and cross-talk between human macrophages and endothelial cells, resulting in augmented inflammatory responses to I-R. Remarkably, the authors found that selective depletion of alveolar macrophages rendered mice resistant to ventilated lung I-R injury.


CONCLUSIONS
The data reveal that alveolar macrophages and the pattern recognition receptor toll-like receptor-4 are involved in the generation of the early inflammatory response to lung I-R injury.
Department of Anesthesia and Perioperative Care, San Francisco General Hospital, University of California, San Francisco, CA, USA. prakasha@anesthesia.ucsf.edu
Arun
A
Prakash
Kailin R
KR
Mesa
Kevin
K
Wilhelmsen
Fengyun
F
Xu
Jeffrey M
JM
Dodd-o
Judith
J
Hellman
D055371:Acute Lung Injury / Q000209:etiology / Q000473:pathology*; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D018845:CD11 Antigens / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D004002:Clodronic Acid / Q000008:administration & dosage / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D008081:Liposomes; D008168:Lung / Q000473:pathology; D016676:Macrophages, Alveolar / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D020556:Neutrophil Infiltration; D009752:Nutritional Status; D001261:Pulmonary Atelectasis / Q000473:pathology; D011652:Pulmonary Circulation / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D015427:Reperfusion Injury / Q000473:pathology*; D012121:Respiration, Artificial; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000502:physiology; D051197:Toll-Like Receptor 4 / Q000502:physiology*
D018712:Analgesics, Non-Narcotic; D018845:CD11 Antigens; D016207:Cytokines; D008081:Liposomes; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D004002:Clodronic Acid