Figure 1

Microglial cells upregulate Toll-like receptor 2 in response to transient ischemic brain injury. (A, B) Photomicrographs of in situ hybridization for Toll-like receptor (TLR) 2 mRNA in wild type (WT) mice 24 h after ischemic injury, indicating marked induction of TLR2 on the ipsilateral side shown in low (A, left) and high (A, right) magnification, in contrast to the contralateral side where no positive S³⁵ signal was observed (B). (C, D, E) Double labeling 3, 7 and 14 days after transient middle cerebral artery occlusion (MCAO) reveals co-localization of TLR2 (green) and Iba1 (red) in WT mice, indicating that TLR2 are expressed almost exclusively by the microglia/macrophage cell population in both the early and late phase of the response to ischemic brain injury. Scale bar: C, 50 μm.