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J. Venugopal et al.
Figure 4. Blood brain barrier integrity post- stroke. Representative staining immunopos- itive to Fibrinogen in the peri-infact area of Wt,WTbmt, Wt,SCDbmt, IL1R-/-,SCDbmt and IL6-/-,SCDbmt mouse brains, and quantifica- tion (mean ± standard deviation). A Nikon SE upright microscope and a Nikon DS-Fi3 camera was used to capture 10x and 20x images of ipsilateral brain and 10x images of contralateral brain. Dotted line denotes transition between infarcted area and heathy tissue. *P<0.05, **P<0.01, ***P<0.005 as determined by ANOVA.
ABC
Figure 5. Infarct area in response to anakinra. Representative brain sections stained with 4% 2,3,5-triphenyltetrazolium chloride (TTC) in Wt,SCDbmt given one intraperitoneal injection of phosphate buffered saline (PBS) (A) or anakinra (B) immediately post-stroke induction, and quantification of stroke volume (mean ± stan- dard deviation) (C). The brain sections were imaged with a Nikon SMZ-2T microscope and Spot Idea camera model 29.2-13MP using at Nikon 0.45x TV lens and Spot 5.1 software. *P<0.05 as determined by student’s t-test.
antibody to Psgl-1 displayed reduced leukocyte-endothe- lial interactions and reduced levels of circulating selectins.54 Circulating monocytes express Psgl-1 and use this receptor to engage E-selectin when undergoing extravasion from the vasculature to the damaged tissue.55 In agreement with the known role of IL-1β in endothelial activation,4,54 IL1R-/-,SCDbmt mice had lower circulating levels of sEsel post-stroke than Wt,SCDbmt or IL6-/-,SCDbmt mice. The lower sEsel concentrations of IL1R-/-,SCDbmt mice correlated with decreased MAC3-pos- itive macrophages present in the peri-infarct area. A simi- lar decrease in MAC3-positive cells was also attained with post-stroke administration of anakinra. ICAM-1 may also contribute to the leukocyte infiltration as immuno-stain-
ing for ICAM-1 was also reduced in IL1R-/-,SCDbmt mice compared to Wt,SCDbmt mice in the peri-infarct region. This is consistent with a previous in vitro study in which ICAM-1 was upregulated on endothelial cells following exposure to sickled erythrocytes and was further increased in the presence of IL-1β.56
IL-1β has also been shown to reduce BBB integrity.36 A decrease in infarct-associated fibrin(ogen) immunostain- ing, was observed to be significantly decreased in IL1R-/-,SCDbmt mice relative to both Wt,SCDbmt and IL6-/-,SCDbmt mice, suggesting less BBB disruption. As dis- ruption of the BBB can lead to a greater influx of leuko- cytes,57 inhibition of IL-1β-mediated actions on endothe- lial cells may reduce leukocyte accumulation by both
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haematologica | 2021; 106(9)