Cowell Rita M, Xu Haiyan, Galasso John M, Silverstein Faye S
Department of Pediatrics, University of Michigan, Ann Arbor, Mich, USA.
Stroke. 2002 Mar;33(3):795-801. doi: 10.1161/hs0302.103740.
Macrophage inflammatory protein (MIP)-1alpha is a well-characterized monocyte chemoattractant; its role in regulating monocyte and microglial recruitment and activation in the injured neonatal brain is unknown. We evaluated the impact of acute hypoxic-ischemic (HI) brain injury on the expression of MIP-1alpha in neonatal rat brain.
To elicit forebrain ischemic injury, 7-day-old (P7) rats underwent right carotid ligation, followed by 2.5 hours of 8% oxygen exposure. We used an enzyme-linked immunosorbent assay and immunohistochemistry to detect MIP-1alpha; double-labeling immunofluorescence assays were analyzed with confocal microscopy to identify cellular sources of MIP-1alpha. Immunocytochemistry assays were also used to detect 2 MIP-1alpha receptors, CCR1 and CCR5.
We found marked increases in tissue concentrations of MIP-1alpha in the HI cerebral hemisphere, peaking from 8 to 72 hours after lesioning. Immunocytochemistry assays revealed that MIP-1alpha was constitutively expressed in physiologically activated microglia; from 8 to 120 hours after lesioning, MIP-1alpha immunoreactive monocytes and microglia accumulated in the lesion territory. In immunoreactive cells, MIP-1alpha was diffusely distributed throughout the cytoplasm at early post-HI time intervals; by 72 hours, MIP-1alpha immunoreactivity was typically concentrated adjacent to the nucleus, a pattern indicative of active MIP-1alpha production. In P7 to P12 brain, many cells expressed MIP-1alpha receptors; both CCR1 and CCR5 immunoreactivity were localized to endothelium and ependyma; CCR1-immunoreactive astrocytes and neurons and CCR5-immunoreactive microglia were also identified.
These data implicate MIP-1alpha as a mediator of the complex and sustained inflammatory response initiated by perinatal HI braininjury.
巨噬细胞炎性蛋白（MIP）-1α是一种特性明确的单核细胞趋化因子；其在调控新生鼠脑损伤时单核细胞和小胶质细胞的募集与激活中的作用尚不清楚。我们评估了急性缺氧缺血（HI）性脑损伤对新生大鼠脑内MIP-1α表达的影响。
为引发前脑缺血损伤，7日龄（P7）大鼠接受右侧颈动脉结扎，随后暴露于8%氧气环境2.5小时。我们采用酶联免疫吸附测定和免疫组织化学法检测MIP-1α；通过共聚焦显微镜分析双标免疫荧光测定以确定MIP-1α的细胞来源。免疫细胞化学测定还用于检测两种MIP-1α受体，CCR1和CCR5。
我们发现HI脑半球中MIP-1α的组织浓度显著增加，在损伤后8至72小时达到峰值。免疫细胞化学测定显示，MIP-1α在生理激活的小胶质细胞中组成性表达；在损伤后8至120小时，MIP-1α免疫反应性单核细胞和小胶质细胞在损伤区域积聚。在免疫反应性细胞中，HI后早期MIP-1α弥漫分布于整个细胞质；到72小时时，MIP-1α免疫反应性通常集中在细胞核附近，这一模式表明MIP-1α处于活跃产生状态。在P7至P12脑内，许多细胞表达MIP-1α受体；CCR1和CCR5免疫反应性均定位于内皮细胞和室管膜；还鉴定出CCR1免疫反应性星形胶质细胞和神经元以及CCR5免疫反应性小胶质细胞。
这些数据表明MIP-1α是围产期HI脑损伤引发的复杂且持续的炎症反应的介质。
