Fig. 6: MC-derived IL-17A induces graded expression of ICAM-1 and CXCL1 in pericytes.

MC^deficient animals were injected with BMMC from WT (MC^WT) or IL-17A^KO (MC^IL-17AKO) mice. Four months later, MC-reconstituted mice were stimulated with TNF (300 ng) for 4 h. Cremaster muscles were collected and immunostained for neutrophils (MRP14), MCs (avidin), pericytes (α-SMA) and ICAM-1 or CXCL1. a Generation of MC-reconstituted mice. b Low-magnification image of the cremasteric microcirculation in MC^WT and MC^IL-17AKO mice depicting the reconstitution of MCs, scale bars 100 µm. c Number of perivascular MCs in MC^WT and MC^IL-17AKO mice (n = 5 mice). d, e Quantification of d ICAM-1 and e CXCL1 MFI on pericytes (n = 5 mice). f Images of post-capillary venules in TNF-treated MC^WT and MC^IL-17AKO mice showing increased expression of ICAM-1 in MC^WT but not in MC^IL-17AKO mice on pericytes, scale bars 5 µm. g Quantification of pericyte ICAM-1 MFI in regions at 5 µm interval from a perivascular MC in TNF-treated MC^WT and MC^IL-17AKO mice (n = 28 MC^WT, 27 MC^IL-17AKO perivascular MC regions, data pooled from five mice, ***p value < 0.0001, ^###p value < 0.0001). h Quantification of pericyte CXCL1 MFI in regions at 5 µm interval from a perivascular MC in TNF-treated MC^WT and MC^IL-17AKO mice, (n = 19 MC^WT, 27 MC^IL-17AKO perivascular MC regions, data pooled from five mice, **p value = 0.0088, ^##p value = 0.0012). ICAM-1 and CXCL1 MFI were normalised to the more distal region (i.e., 15–20 µm). i Extravascular neutrophils in MC^WT or MC^IL-17AKO mice (n = 5 mice, p value = 0.0094). j–k Correlation of the number of extravascular neutrophils and perivascular MCs in j MC^WT (n = 58 venules) and k MC^IL-17AKO (n = 60 venules); data pooled from five mice. Line indicated linear regression and dashed lines 95% confidence band. Mean±SEM (each mouse represents one independent experiment). c–e, i two-tailed Student’s t test; g, h two-way ANOVA followed by Sidak’s post-hoc test; j, k Spearman’s rank correlation test. **p < 0.01, ***p < 0.001 as compared to MC^WT or 20-15 µm region or as indicated ^##p < 0.01, ^###p < 0.001 (ns = not significant). Source data are provided as a Source Data file.