Argon mediates protection by interleukin-8 suppression via a TLR2/TLR4/STAT3/NF-B pathway in a model of apoptosis in neuroblastoma cells invitro and following ischemia-reperfusion injury in rat retina invivo

摘要

Argon has recently come into scientific focus as a neuroprotective agent. The underlying neuroprotective mechanism remains unknown although toll-like receptors were recently suggested to play an important role. We hypothesized that TLR-associated downstream transcription factors are responsible for argon's effects, leading to anti-apoptotic and anti-inflammatory properties. Apoptosis was induced in human neuroblastoma cells. Immediately afterwards, argon treatment (75 Vol% for 2h) was initiated. Cells were analyzed, measuring mitochondrial membrane potential, reactive-oxygen-species, annexin-V/propidium iodide staining, transcription factor phosphorylation and binding activity as well as protein and mRNA expression of interleukins. Argon's invivo effects were analyzed by quantification of retinal ganglion cell density, mRNA expression, serum cytokine analysis and immunohistochemistry after retinal ischemia reperfusion injury (IRI) in rats. Argon diminished rotenone-induced kappa-light-chain-enhancer' of activated B-cells (NF-B) and signal transducer and activator of transcription 3 (STAT3) but not STAT5 or cAMP-response element-binding protein (CREB) phosphorylation and DNA-binding activity. Argon treatment attenuated apoptosis by preservation of mitochondrial membrane potential and decline in reactive oxygen species (ROS) generation. NF-B and STAT3 inhibition, as well as TLR2 and TLR4 inhibition reversed argon's effects on IL-8 mRNA expression. Argon attenuated rotenone-induced IL-8 protein and mRNA expression invitro. Inhibition of TLR2 and 4 attenuated argon's protective effect invivo reducing IRI driven retinal IL-8 expression. IL-8 expression was found in the retina in co-localization with Muller cells and retinal ganglion cells. Argon mediates its neuroprotective effects by TLR-mediated regulation of transcription factors NF-B and STAT3, thus decreasing interleukin-8 expression invitro and invivo. These findings may open up new opportunities to effectively treat cerebral ischemia and reperfusion injury through the inhalation of argon.