Carnosol suppresses interleukin-6 production in mouse lungs injured by ischemia-reperfusion operation and in RAW264.7 macrophages treated with lipopolysaccharide

Carnosol is a naturally occurring herbal compound, known for its antioxidative properties. We previously found that carnosol protected mouse lungs from ischemia-reperfusion injury in ex vivo cultures. To elucidate the molecular mechanisms underpinning carnosol-mediated lung protection, we analyzed modes of interleukin-6 (IL-6) gene expression, which is associated with lung ischemia-reperfusion injury. Microarray analysis of mouse lungs suggested that IL-6 mRNA levels were elevated in the mouse lungs subjected to clamp-reperfusion, which was associated with elevated levels of other inflammatory modulators, such as activating transcription factor 3 (ATF3). Carnosol pretreatment lowered the IL-6 protein levels in mouse lung homogenates prepared after the clamp-reperfusion. On the other hand, the ATF3 gene expression was negatively correlated with that of IL-6 in RAW264.7 cells. IL-6 mRNA levels and gene promoter activities were suppressed by carnosol in RAW264.7 cells, but rescued by ATF3 knockdown. When RAW264.7 cells were subjected to hypoxia-reoxygenation, carnosol treatment lowered oxygen consumption after reoxygenation, which was coupled with a correlation with a transient production of mitochondrial reactive oxygen species and following ATF3 gene expression. These results suggest that carnosol treatment could be a new strategy for protecting lungs from ischemia-reperfusion injury by modulating the ATF3-IL-6 axis.Key words: carnosol, IL-6, ATF3, lung ischemia-reperfusion injury.Le carnosol est un compose naturel d'origine vegetale connu pour ses proprietes antioxydantes. Les auteurs avaient precedemment trouve que le carnosol protegeait le poumon de la souris du dommage d'ischemie-reperfiision en culture ex vivo. Afin d'elucider les mecanismes moleculaires qui sous-tendent la protection du poumon par le carnosol, ils ont analyse l'expression genique de l'interleukine-6 (IL-6), associee au dommage d'ischemie-reperfusion pulmonaire. Une analyse sur microreseau de poumons de souris a revele que les niveaux de l'ARNm d'IL-6 etaient eleves dans les poumons des souris soumises a un clamp-reperfusion, qui etaient associes a des niveaux eleves d'autres modulateurs inflammatoires tels que le facteur ATF3 (pour << activating transcription factor 3 >>). Un pretraitement au carnosol diminuait les niveaux proteiques d'IL-6 dans des homogenats de poumons prepares apres le clamp-reperfusion. Par contre, l'expression genique d'ATF3 etait correlee negativement avec celle de l'IL-6 chez les cellules RAW264.7. Les niveaux d'ARNm d'IL-6 et l'activite du promoteur du gene etaient diminues par le carnosol dans les cellules RAW264.7, mais retablis par le knock-down d'ATF3. Lorsque les cellules RAW264.7 etaient soumises a une hypoxie-reoxygenation, le traitement au carnosol diminuait la consommation d'oxygene apres la reoxygenation, diminution couplee a une production transitoire de derives reactifs d'oxygene mitochondriaux a la suite de l'expression d'ATF3. Ces resultats suggerent que le traitement au carnosol pourrait constituer une nouvelle strategie de protection des poumons des dommages d'ischemie-reperfusion en modulant l'axe ATF3-IL-6. [Traduit par la Redaction]Mots-cles: carnosol, IL-6, ATF3, dommage pulmonaire d'ischemie-reperfusion.
IntroductionInflammatory cytokines play important roles in the development of tissue injury after ischemia-reperfusion (Beckers et al. 2017). Proper control of inflammatory signals is considered an excellent prognosis in surgery for [...]