Fig 2: IL-17Rb and CXCL5 up-regulation in injured white matter vasculatureSchematic representation of IL-17/CXCL5 signaling in chronically injured cerebral endothelia (A). TRAP-qPCR fold expression compared with average fpkm of top DEGs from white matter endothelia (*adjusted p < 0.05) (B). Weight-adjusted ELISA values (pg/mL) for murine CXCL5 in retro-orbital blood samples from CFD (black) and HFD (red) animals (n = 4/grp, p = 0.0355) (C). Immunofluorescence labeling for IL-17Rb (green, D) and CXCL5 (green, E) is absent in white matter vasculature of Tie2-Cre;tdTomato mice on CFD (left panels) and abundant in white matter vasculature of Tie2-Cre;tdTomato mice on HFD (right panels). Single-channel labeling for IL17Rb (bottom panels, D) and CXCL5 (bottom panels, E) show heterogeneous endothelial expression. Labeling for GLUT-1 (blue), CXCL5 (red), and PDGFRa (green) at 7 days post-stroke in animals on CFD (left) and HFD (right). Inset boxes from the peri-infarct tissue (top) masked for GLUT-1 (white) with only co-localized CXCL5 (purple) (bottom). Graph of percentage of co-localized CXCL5+/GLUT-1+ voxels (****p < 0.0001) (F). Error bars represent S.E.M.Scale bars: 50 µm (F), 20 µm (D), and 10 µm (E).

Fig 3: IL-17B/IL-17Rb/CXCL5 signaling is a vessel-to-OPC signal in white matter vasculatureHuman brain microvascular endothelial cells were stimulated with IL-17 ligands A–E (250 ng/mL) and CXCL5 levels measured in conditioned media 48 h after stimulation (*p = 0.0372 by Kruskal-Wallis H test; **post-hoc comparison for IL-17B versus no ligand, adjusted p = 0.0178) (A). Phalloidin+ cellular area in O4+ OPCs grown in vitro exposed to vehicle (top panel) or recombinant CXCL5 (bottom panel) for 48 h (p < 0.0001, F = 9.82 by one-way ANOVA) (B). Approach for CXCL5 transgenic-viral gain of function in subcortical white matter of Tie2-Cre;tdTomato mice (top panel) (C). PDGFRa+ OPC (green) labeling in GFP-transduced Tie2-Cre;tdTomato mice (red, left panel) and CXCL5-GFP-transduced Tie2-Cre;tdTomato mice (right panel). Representative masked cellular profiles of PDGFRa+ cell area (bottom panels). Schematic of anti-IL-17B antibody treatment (top panel) (D). PDGFRa+ OPC (green) labeling in control IgG-treated Tie2-Cre:tdT mice (left panel) and anti-IL-17B IgG-treated Tie2-Cre:tdT mice (right panel). Representative masked cellular profiles of PDGFRa+ cell area (bottom panels). Proportion of OPCs per unit distance from vessel (0–35 µm) in each condition (total measured cell number per condition in parentheses) (E). Average distance of OPCs to vessel (***p = 0.0005, F = 6.06 by one-way ANOVA; **adjusted p = 0.0039; *adjusted p = 0.0168) (F). Average in vivo PDGFRa+ OPC cell area (**p = 0.0068, F = 7.38 by one-way ANOVA; **adjusted p = 0.002) (G). Graph of co-localized CXCL5+/GLUT-1+ voxels in anti-IL-17B IgG-treated animals (n = 4/grp; *p = 0.018) (H). Error bars represent S.E.M.Scale bars: 10 µm