Seminars Archive

Visualization of the mouse brain after ischemic injury, and the involvement of TLR-2-related signaling pathway in the consequences of the brain ischemia

Abstract
Toll-like receptor 2 (TLR2) is involved in innate immunity in the brain and in the events following the ischemic stroke. In order to analyze TLR-2-related signaling pathway after transient medial cerebral artery occluison (MCAO) in the mouse brain, TLR2−/− mice were compared to the wild type mice. TLR2 deficiency affected post-stroke immune response resulting in delayed increase of the brain injury, which was in the acute phase smaller, but 7 days onwards bigger than in the wild type mice. Real-time PCR expression of genes involved in the signaling pathway showed that TLR2 loss resulted in the decrease of proinflammatory response after brain ischemia. The expression of Casp8, as a hallmark of apoptosis, was increased in TLR2−/− mice, in particular in the late phase of recovery. This was followed by increase of apoptotic cells in these mice, which were more numerous 7 and 14 days after ischemic injury, but not in the acute phase (3 days after ischemia). These results suggested that TLR-2-related signaling is important in the regulation and timing of inflammation and apoptosis after ischemic injury in the mouse brain. The consequences of ischemia in the brain were visualized by in vivo bioluminescence imaging using luciferase reporter, and by ex vivo X-ray uCT using the nonionic radio-contrast agent.