Abstract
Background: Perioperative damage of neuronal tissue due to insufficient cerebral circulation as a result of hypotension or stroke, lead to permanent destruction and functional impairment via apoptotic and inflammatory pathways. Recently, the noble gas argon has been shown to exert neuroprotective effects. Despite intensive research, the exact mechanism remains unclear. Methods: In-vitro, after injury of human neuroblastoma cells with rotenone over a period of four hours, postconditioning with argon 75 Vol% was performed for 2. In-vivo, retinal ischemia reperfusion injury in the rat was induced by increasing intraocular pressure for 1 hour (h). Upon reperfusion, argon was administered by inhalation for 2 h. Results: In summary, argon reduced binding activity of transcription factors involved in regulation of neuronal damage such as STAT3 (Signal transducer and activator of transcription 3), NF-kB (Nuclear factor `kappa-light-chain-enhancer´ of activated B-cells), AP-1 (Activator protein 1) and Nrf-2 (Nuclear factor erythroid 2-related factor 2). Flow cytometry analysis showed that argon down-regulated the Fas-Ligand. Since some of these transcription factors were regulated via toll-like receptors (TLR), their effects could be eliminated - at least in part - by OxPAPC (TLR2 and -4 inhibitor). Argon was able to reduce the quantity and the activity of neuronal microglia after ischemia-reperfusion injury. Consecutively, qPCR (quantitative Polymerase chain reaction) showed a reduction of the pro-inflammatory cytokines IL-1α (Interleukin-1α), IL-1ß (Interleukin-1ß), IL-6 (Interleukin 6), TNFα (Tumor necrosis factor alpha) and iNOS (inducible Nitric oxide synthase). Conclusion: Argon reduced the extent of inflammation after neuronal injury by suppression of transcription factors crucial for microglia activation. The therapeutic use of the noble gas would be ideal for treating in the context of neuronal damage due to the lack of known side effects and narcotic properties with preservation of neurological assessability. Although preclinical studies are promising, further investigations are required before argon can be approved for use in patients.
Immune‐Responsive Gene 1/Itaconate Activates Nuclear Factor Erythroid 2–Related Factor 2 in Hepatocytes to Protect Against Liver Ischemia–Reperfusion Injury
