Interleukin-7 is produced by afferent lymphatic vessels and supports lymphatic drainage

M Iolyeva, D Aebischer, ST Proulx… - Blood, The Journal …, 2013 - ashpublications.org
M Iolyeva, D Aebischer, ST Proulx, AH Willrodt, T Ecoiffier, S Häner, G Bouchaud, C Krieg
Blood, The Journal of the American Society of Hematology, 2013ashpublications.org
Abstract The cytokine interleukin (IL)-7 exerts essential roles in lymph node (LN)
organogenesis and lymphocyte development and homeostasis. Recent studies have
identified lymphatic endothelial cells (LECs) as a major source of IL-7 in LNs. Here, we
report that LECs not only produce IL-7, but also express the IL-7 receptor chains IL-7Rα and
CD132. Stimulation with recombinant IL-7 enhanced LEC in vitro activity and induced
lymphangiogenesis in the cornea of wild-type (WT) mice. Whereas in IL-7Rα−/− mice …
Abstract
The cytokine interleukin (IL)-7 exerts essential roles in lymph node (LN) organogenesis and lymphocyte development and homeostasis. Recent studies have identified lymphatic endothelial cells (LECs) as a major source of IL-7 in LNs. Here, we report that LECs not only produce IL-7, but also express the IL-7 receptor chains IL-7Rα and CD132. Stimulation with recombinant IL-7 enhanced LEC in vitro activity and induced lymphangiogenesis in the cornea of wild-type (WT) mice. Whereas in IL-7Rα−/− mice, dermal lymphatic vessels (LVs) were abnormally organized and lymphatic drainage was compromised, transgenic overexpression of IL-7 in mice resulted in an expanded dermal LV network with increased drainage function. Moreover, systemic treatment with recombinant IL-7 enhanced lymphatic drainage in the skin of WT mice and of mice devoid of lymphocytes. Experiments in IL-7Rα−/− bone marrow chimeras demonstrated that the drainage-enhancing activity of IL-7 was exclusively dependent on IL-7Rα expression in stromal but not in hematopoietic cells. Finally, near-infrared in vivo imaging performed in IL-7Rα−/− mice revealed that the pumping activity of collecting vessels was normal but fluid uptake into lymphatic capillaries was defective. Overall, our data point toward an unexpected new role for IL-7 as a potential autocrine mediator of lymphatic drainage.
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