Department of Neurology and Neurological Sciences, Stanford University Medical School, Stanford, CA 94305-5489, USA.
J Neuroinflammation. 2010 Oct 11;7:62. doi: 10.1186/1742-2094-7-62.
TGFβ is both neuroprotective and a key immune system modulator and is likely to be an important target for future stroke therapy. The precise function of increased TGF-β1 after stroke is unknown and its pleiotropic nature means that it may convey a neuroprotective signal, orchestrate glial scarring or function as an important immune system regulator. We therefore investigated the time course and cell-specificity of TGFβ signaling after stroke, and whether its signaling pattern is altered by gender and aging.
We performed distal middle cerebral artery occlusion strokes on 5 and 18 month old TGFβ reporter mice to get a readout of TGFβ responses after stroke in real time. To determine which cell type is the source of increased TGFβ production after stroke, brain sections were stained with an anti-TGFβ antibody, colocalized with markers for reactive astrocytes, neurons, and activated microglia. To determine which cells are responding to TGFβ after stroke, brain sections were double-labelled with anti-pSmad2, a marker of TGFβ signaling, and markers of neurons, oligodendrocytes, endothelial cells, astrocytes and microglia.
TGFβ signaling increased 2 fold after stroke, beginning on day 1 and peaking on day 7. This pattern of increase was preserved in old animals and absolute TGFβ signaling in the brain increased with age. Activated microglia and macrophages were the predominant source of increased TGFβ after stroke and astrocytes and activated microglia and macrophages demonstrated dramatic upregulation of TGFβ signaling after stroke. TGFβ signaling in neurons and oligodendrocytes did not undergo marked changes.
We found that TGFβ signaling increases with age and that astrocytes and activated microglia and macrophages are the main cell types that undergo increased TGFβ signaling in response to post-stroke increases in TGFβ. Therefore increased TGFβ after stroke likely regulates glial scar formation and the immune response to stroke.
TGFβ 既具有神经保护作用，又是免疫系统的关键调节剂，很可能成为未来中风治疗的重要靶点。中风后 TGF-β1 增加的确切功能尚不清楚，其多效性意味着它可能传递神经保护信号、协调神经胶质瘢痕形成，或作为重要的免疫系统调节剂发挥作用。因此，我们研究了中风后 TGFβ 信号的时间过程和细胞特异性，以及其信号模式是否因性别和衰老而改变。
我们对 5 个月大和 18 个月大的 TGFβ 报告小鼠进行远端大脑中动脉闭塞性中风，以实时获得中风后 TGFβ 反应的读数。为了确定中风后增加 TGFβ 产生的细胞类型，我们用抗 TGFβ 抗体对脑切片进行染色，与反应性星形胶质细胞、神经元和激活的小胶质细胞的标志物共定位。为了确定中风后哪些细胞对 TGFβ 有反应，我们用抗 pSmad2（TGFβ 信号的标志物）和神经元、少突胶质细胞、内皮细胞、星形胶质细胞和小胶质细胞的标志物对脑切片进行双标记。
中风后 TGFβ 信号增加了 2 倍，从第 1 天开始增加，并在第 7 天达到峰值。这种增加模式在老年动物中得以保留，并且大脑中 TGFβ 的绝对信号随年龄增长而增加。激活的小胶质细胞和巨噬细胞是中风后增加 TGFβ 的主要来源，而星形胶质细胞和激活的小胶质细胞和巨噬细胞在中风后 TGFβ 信号的表达显著上调。神经元和少突胶质细胞的 TGFβ 信号没有发生明显变化。
我们发现 TGFβ 信号随年龄增长而增加，星形胶质细胞和激活的小胶质细胞和巨噬细胞是对中风后 TGFβ 增加作出反应的主要细胞类型，它们的 TGFβ 信号增加。因此，中风后 TGFβ 可能调节神经胶质瘢痕形成和对中风的免疫反应。
