Therapeutic distant organ effects of regional hypothermia during mesenteric ischemia-reperfusion injury.
BACKGROUND
Mesenteric ischemia-reperfusion injury (IRI) leads to systemic inflammation and multiple organ failure in clinical and laboratory settings. We investigated the lung structural, functional, and genomic response to mesenteric IRI with and without regional intraischemic hypothermia (RIH) in rodents and hypothesized that RIH would protect the lung and preferentially modulate the distant organ transcriptome under these conditions.


METHODS
Sprague-Dawley rats underwent sham laparotomy or superior mesenteric artery occlusion (SMAO) for 60 minutes with or without RIH. Gut temperature was maintained at 15°-20°C during SMAO, and systemic normothermia (37°C) was maintained throughout the study period. At 6 or 24 hours, lung tissue was collected for (1) histology, (2) myeloperoxidase activity, (3) bronchoalveolar lavage (BAL) fluid protein concentrations, (4) lung wet/dry ratios, and (5) total RNA isolation and hybridization to Illumina's Sentrix BeadChips (>22,000 probes) for gene expression profiling. Significantly affected genes (false discovery rate <5% and fold change ≥1.5) were linked to gene ontology (GO) terms using MAPPFinder, and hypothermia-suppressed genes were further analyzed with Pubmatrix.


RESULTS
Mesenteric IRI-induced lung injury, as evidenced by leukocyte trafficking, alveolar hemorrhage, and increased BAL protein and wet/dry ratios, and activated a proinflammatory lung transcriptome compared with sham. In contrast, rats treated with RIH exhibited lung histology, BAL protein, and wet/dry ratios similar to sham. At 6 hours, GO analysis identified 232 hypothermia-suppressed genes related to inflammation, innate immune response, and cell adhesion, and 33 hypothermia-activated genes related to lipid and amine metabolism and defense response. Quantitative real-time polymerase chain reaction validated select array changes in top hypothermia-suppressed genes lipocalin-2 (lcn-2) and chemokine ligand 1 (CXCL-1), prominent genes associated with neutrophil activation and trafficking.


CONCLUSIONS
Therapeutic hypothermia during SMAO provides distant organ protection and preferentially modulates the IRI-activated transcriptome in the rat lung. This study identifies potential novel diagnostic and therapeutic targets of mesenteric IRI and provides a platform for further mechanistic study of hypothermic protection at the cellular and subcellular level.
Santora
Rachel J
RJ
Department of Surgery, The Methodist Hospital and Research Institute, Houston, Tex, USA.
Lie
Mihaela L
ML
Grigoryev
Dmitry N
DN
Nasir
Omer
O
Moore
Frederick A
FA
Hassoun
Heitham T
HT
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D002448:Cell Adhesion / Q000235:genetics; D002634:Chemotaxis, Leukocyte / Q000235:genetics; D016000:Cluster Analysis; D004195:Disease Models, Animal; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation; D007036:Hypothermia, Induced; D007113:Immunity, Innate / Q000235:genetics; D018836:Inflammation Mediators / Q000378:metabolism; D008168:Lung / Q000098:blood supply / Q000276:immunology* / Q000473:pathology; D008297:Male; D008641:Mesenteric Vascular Occlusion / Q000150:complications / Q000628:therapy*; D018375:Neutrophil Activation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D011014:Pneumonia / Q000209:etiology / Q000235:genetics / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D016133:Polymerase Chain Reaction; D011654:Pulmonary Edema / Q000276:immunology / Q000517:prevention & control; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000209:etiology / Q000235:genetics / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D015203:Reproducibility of Results; D013997:Time Factors
D018836:Inflammation Mediators