Gesuete Raffaella, Christensen Sara N, Bahjat Frances R, Packard Amy E B, Stevens Susan L, Liu Mingyue, Salazar Andres M, Stenzel-Poore Mary P
From the Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, OR (R.G., S.N.C., F.R.B., A.E.B.P., S.L.S., M.L., M.P.S.-P.); and Oncovir, Washington, DC (A.M.S.).
Stroke. 2016 Jan;47(1):262-6. doi: 10.1161/STROKEAHA.115.010329. Epub 2015 Nov 12.
Preconditioning with poly-l-lysine and carboxymethylcellulose (ICLC) provides robust neuroprotection from cerebral ischemia in a mouse stroke model. However, the receptor that mediates neuroprotection is unknown. As a synthetic double-stranded RNA, poly-ICLC may bind endosomal Toll-like receptor 3 or one of the cytosolic retinoic acid-inducible gene-I-like receptor family members, retinoic acid-inducible gene-I, or melanoma differentiation-associated protein 5. Activation of these receptors culminates in type I interferons (IFN-α/β) induction-a response required for poly-ICLC-induced neuroprotection. In this study, we investigate the receptor required for poly-ICLC-induced neuroprotection.
Toll-like receptor 3, melanoma differentiation-associated protein 5-, and IFN-promoter stimulator 1-deficient mice were treated with poly-ICLC 24 hours before middle cerebral artery occlusion. Infarct volume was measured 24 hours after stroke to identify the receptor signaling pathways involved in protection. IFN-α/β induction was measured in plasma samples collected 6 hours after poly-ICLC treatment. IFN-β-deficient mice were used to test the requirement of IFN-β for poly-ICLC-induced neuroprotection. Mice were treated with recombinant IFN-α-A to test the role of IFN-α as a potential mediator of neuroprotection.
Poly-ICLC induction of both neuroprotection and systemic IFN-α/β requires the cytosolic receptor melanoma differentiation-associated protein 5 and the adapter molecule IFN-promoter stimulator 1, whereas it is independent of Toll-like receptor 3. IFN-β is not required for poly-ICLC-induced neuroprotection. IFN-α treatment protects against stroke.
Poly-ICLC preconditioning is mediated by melanoma differentiation-associated protein 5 and its adaptor molecule IFN-promoter stimulator 1. This is the first evidence that a cytosolic receptor can mediate neuroprotection, providing a new target for the development of therapeutic agents to protect the brain from ischemic injury.
在小鼠脑卒中模型中，用聚-L-赖氨酸和羧甲基纤维素（ICLC）进行预处理可对脑缺血提供强大的神经保护作用。然而，介导神经保护作用的受体尚不清楚。作为一种合成双链RNA，聚-ICLC可能与内体Toll样受体3或胞质视黄酸诱导基因-I样受体家族成员之一、视黄酸诱导基因-I或黑色素瘤分化相关蛋白5结合。这些受体的激活最终导致I型干扰素（IFN-α/β）的诱导——这是聚-ICLC诱导神经保护作用所必需的反应。在本研究中，我们调查聚-ICLC诱导神经保护作用所需的受体。
在大脑中动脉闭塞前24小时，用聚-ICLC处理Toll样受体3、黑色素瘤分化相关蛋白5和IFN启动子刺激物1缺陷型小鼠。在脑卒中后24小时测量梗死体积，以确定参与保护作用的受体信号通路。在聚-ICLC处理后6小时采集的血浆样本中测量IFN-α/β的诱导情况。使用IFN-β缺陷型小鼠来测试IFN-β对聚-ICLC诱导神经保护作用的必要性。用重组IFN-α-A处理小鼠，以测试IFN-α作为神经保护潜在介质的作用。
聚-ICLC诱导神经保护作用和全身IFN-α/β均需要胞质受体黑色素瘤分化相关蛋白5和衔接分子IFN启动子刺激物1，而与Toll样受体3无关。IFN-β对聚-ICLC诱导的神经保护作用不是必需的。IFN-α治疗可预防脑卒中。
聚-ICLC预处理由黑色素瘤分化相关蛋白5及其衔接分子IFN启动子刺激物1介导。这是胞质受体可介导神经保护作用的首个证据，为开发保护大脑免受缺血性损伤的治疗药物提供了新靶点。
