Ischemic brain injury triggers neuronal cell death by apoptosis via caspase activation and by necroptosis through activation of the receptor-interacting protein kinases （RIPK） associated with the tumor necrosis fact...Ischemic brain injury triggers neuronal cell death by apoptosis via caspase activation and by necroptosis through activation of the receptor-interacting protein kinases （RIPK） associated with the tumor necrosis factor-alpha （TNF-a）/death receptor. Recent evidence shows RIPK inhibitors are neuroprotective and al- leviate ischemic brain injury in a number of animal models, however, most have not yet undergone clinical trials and safety in humans remains in question. Dabrafenib, originally identified as a B-raf inhibitor that is currently used to treat melanoma, was later revealed to be a potent RIPK3 inhibitor at micromolar con- centrations. Here, we investigated whether Dabrafenib would show a similar neuroprotective effect in mice subjected to ischemic brain injury by photothrombosis. Dabrafenib administered intraperitoneally at 10 mg/ kg one hour after photothrombosis-induced focal ischemic injury significantly reduced infarct lesion size in C57BL6 mice the following day, accompanied by a markedly attenuated upregulation of TNF-u. However, subsequent lower doses （5 mg/kg/day） failed to sustain this neuroprotective effect after 4 days. Dabrafenib bl ocked lipopolysaccharides-induced activation of TNF-ct in bone marrow-derived macrophages, suggesting that Dabrafenib may attenuate TNF-ct-induced necroptotic pathway after ischemic brain injury. Since Dab- rafenib is already in clinical use for the treatment of melanoma, it might be repurposed for stroke therapy.展开更多
基金supported by grants from the Heart and Stroke Foundation of Canada(HHC,AFRS)the Canadian Institutes of Health Research(to HHC and AFRS)supported by a Mid-Career Investigator Award from the Heart and Stroke Foundation of Ontario
文摘Ischemic brain injury triggers neuronal cell death by apoptosis via caspase activation and by necroptosis through activation of the receptor-interacting protein kinases （RIPK） associated with the tumor necrosis factor-alpha （TNF-a）/death receptor. Recent evidence shows RIPK inhibitors are neuroprotective and al- leviate ischemic brain injury in a number of animal models, however, most have not yet undergone clinical trials and safety in humans remains in question. Dabrafenib, originally identified as a B-raf inhibitor that is currently used to treat melanoma, was later revealed to be a potent RIPK3 inhibitor at micromolar con- centrations. Here, we investigated whether Dabrafenib would show a similar neuroprotective effect in mice subjected to ischemic brain injury by photothrombosis. Dabrafenib administered intraperitoneally at 10 mg/ kg one hour after photothrombosis-induced focal ischemic injury significantly reduced infarct lesion size in C57BL6 mice the following day, accompanied by a markedly attenuated upregulation of TNF-u. However, subsequent lower doses （5 mg/kg/day） failed to sustain this neuroprotective effect after 4 days. Dabrafenib bl ocked lipopolysaccharides-induced activation of TNF-ct in bone marrow-derived macrophages, suggesting that Dabrafenib may attenuate TNF-ct-induced necroptotic pathway after ischemic brain injury. Since Dab- rafenib is already in clinical use for the treatment of melanoma, it might be repurposed for stroke therapy.
