Figure 1.

Inflamed aged stroma promotes aberrant neutrophil transendothelial cell migration

(A–G) Young (2–4 months) and aged (≥18 months) mice were treated intrascrotally (i.s.) with PBS or IL-1β and neutrophil responses in cremasteric post-capillary venules analyzed. Leukocyte (A) rolling flux and (B) firm adhesion in WT mice as quantified by brightfield IVM (n = 3–16 mice/group). Neutrophil (C) normal TEM events (n = 5-7 mice/group; Video S1), (D) total extravasation (n = 5–7 mice/group), and (E) related representative images of Lyz2-EGFP-ki venules, as assessed by confocal IVM (scale bar: 15 μm).

(F) Time-lapse confocal images (Video S2) showing a neutrophil rTEM event in an IL-1β-stimulated aged Lyz2-EGFP-ki venule with the neutrophil in the sub-endothelial space (t = 17 min) re-entering the vascular lumen (t = 26 min to t = 46 min). Top panel: en face luminal view; bottom panel: cross-sections; arrows: direction of neutrophil motility (scale bar: 10 μm).

(G) Frequency of neutrophil rTEM in Lyz2-EGFP-ki stimulated tissues (n = 5–6 mice/group).

(H) The generation of Y→Y, A→Y, or Y→A chimeras (young ‘Y’; or aged ‘A’) and (I–K) their analysis post treatment with i.s. PBS or IL-1β. Cremaster muscle (I) leukocyte firm adhesion as assessed by brightfield IVM (n = 3-10 mice/group), (J) neutrophil normal TEM events (n = 4-5 mice/group) and (K) frequency of neutrophil rTEM as assessed by confocal IVM (n = 3-5 mice/group). Means ± SEM, #p < 0.05, ##p < 0.01, ###p < 0.001, ####p < 0.0001 relative to aged-matched controls and ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001, ^∗∗∗∗p < 0.0001, n.s. not significant, as indicated.

See also Figure S1.