Department of Molecular Neuroscience (R.N., T.I., N.S., T.Y.), Graduate School of Medicine, Osaka University, Suita, Japan.
Department of Neurosurgery (R.N., H.K.), Graduate School of Medicine, Osaka University, Suita, Japan.
Stroke. 2024 Dec;55(12):2872-2881. doi: 10.1161/STROKEAHA.124.047574. Epub 2024 Oct 30.
Subarachnoid hemorrhage (SAH) can lead to acute or delayed cerebral ischemia. Recent findings have revealed that spasm of microvessels, called microvasospasm, may contribute to SAH-related cerebral ischemia, and perivascular inflammation is considered important in the development of microvasospasms. However, owing to the difficulty in investigating the dynamics of vascular and perivascular events, little is known about the mechanisms underlying microvasospasms.
We established an experimental system aiming to investigate the vascular and perivascular pathology of SAH by combining a SAH mouse model with intravital 2-photon imaging. SAH was induced by intracisternal blood injection, and the distribution of erythrocytes, neutrophil behavior, and morphological changes in the pial arterioles were analyzed over time by 2-photon microscopy imaging. To further explore the role of neutrophils and neutrophil extracellular traps (NETs) in microvasospasm, we performed neutrophil depletion by intraperitoneal administration of neutrophil-specific antibody or NETs removal by intracisternal administration of DNase.
Erythrocytes were immediately distributed in the perivascular space of the arterioles after SAH induction; neutrophils intensively infiltrated the perivascular space within 2 days and subsequently showed NETosis; and pial arterioles in the same region developed pearl-string-like microvasospasms in the subacute phase. Neutrophil depletion significantly reduced the number of microvasospasms. Furthermore, the removal of perivascular NETs drastically reduced microvasospasms.
By establishing a unique experimental system, we demonstrated that perivascular NETs could be a new therapeutic target for microvasospasms.
蛛网膜下腔出血 (SAH) 可导致急性或迟发性脑缺血。最近的研究结果表明，微血管痉挛（称为微血管痉挛）可能导致与 SAH 相关的脑缺血，血管周围炎症被认为在微血管痉挛的发展中很重要。然而，由于难以研究血管和血管周围事件的动态，因此对微血管痉挛的机制知之甚少。
我们建立了一个实验系统，旨在通过结合 SAH 小鼠模型和活体双光子成像来研究 SAH 的血管和血管周围病理学。通过脑室内血液注射诱导 SAH，并通过双光子显微镜成像随时间分析红细胞分布、中性粒细胞行为和脑膜小动脉的形态变化。为了进一步探讨中性粒细胞和中性粒细胞胞外陷阱 (NETs) 在微血管痉挛中的作用，我们通过腹腔内给予中性粒细胞特异性抗体或脑室内给予 DNAse 来进行中性粒细胞耗竭或 NETs 去除。
SAH 诱导后红细胞立即分布在小动脉的血管周围空间；中性粒细胞在 2 天内密集浸润血管周围空间，随后发生 NETosis；同一区域的脑膜小动脉在亚急性期出现串珠样微血管痉挛。中性粒细胞耗竭显著减少了微血管痉挛的数量。此外，血管周围 NETs 的去除大大减少了微血管痉挛。
通过建立一个独特的实验系统，我们证明了血管周围 NETs 可能是微血管痉挛的一个新的治疗靶点。
