Figure 4

Toll-like receptor 2 deficient mice display reduced proliferation of resident microglial cells. (A) Photomicrographs of BrdU immunoreactivity in wild-type (WT) and Toll-like receptor (TLR) 2−/− mice 3 days after transient middle cerebral artery occlusion (MCAO) and their unlesioned controls, respectively. (B) Quantification of BrdU immunoreactivity indicates reduced cell proliferative capacity in TLR2−/− mice compared with WT mice 3 days after transient MCAO. (C) Representative photomicrographs of double immunostaining on WT brain sections 3 days after transient MCAO show almost complete co-localization of BrdU (green) positive cells with Iba1 (red; white arrows). (D) Flow cytometric analysis of the CD45^low/CD11b⁺ (microglial) population proliferation in WT and TLR2−/− mice 3 days after MCAO compared with their contralateral (unlesioned) hemisphere controls. (E) Graph presents quantification of microglial proliferation measured by flow cytometric analysis. Data indicate reduced microglial proliferation in TLR2−/− mice compared with WT mice 3 days after MCAO. (F) Double immunofluorescent labeling reveals co-localization of BrdU (green) and Mac-2 (red; white arrows) in WT brain sections 3 days after transient MCAO. (G) Representative photomicrographs of Mac-2 immunofluorescence in WT and TLR2−/− mice observed 3 days after transient MCAO. (H) Quantification of Mac-2 immunoreactivity 3 days after transient MCAO revealed reduced signals in TLR2−/− mice compared with WT mice. Data (B, H) are indicated as mean ± SEM (n = 4; *P <0.05). Data (E) are expressed as percentage of CD45⁺ events ± SEM (n = 4; *P <0.05). Scale bars: A, G, 100 μm; C, F, 50 μm.