Page 35 - VOL 26 N. 72 - 2015

THE ROLE OF INTERLEUKIN-7 IN LYMPHATIC VESSEL FUNCTION AND ITS THERAPEUTIC POTENTIAL FOR THE TREATMENT OF LYMPHEDEMA AND CHRONIC SKIN INFLAMMATION
MARIA IOLYEVA1, MARTINA VRANOVA1, DAVID AEBISCHER 1, STEFANIE MEIER 1, DANIELA IMPELLIZZIERI 2, ONUR BOYMAN 2,
STEVEN T. PROULX 1 AND CORNELIA HALIN 1
1 Institute of Pharmaceutical Sciences, ETH Zurich, Vladimir-Prelog Weg 1-5/10, 8093 Zurich, Switzerland Email: martina.vranova@pharma.ethz.ch 2 Laboratory of Applied Immunobiology, University of Zurich, Gloriastrasse 30, 8006 Zurich, Switzerland
Interleukin-7 (IL-7) is a cytokine known for its role in T and B cell homeostasis, as well as in lymph node organogenesis. Our lab has recently identified a novel role for IL-7 in lymphatic vessel biology. Lymphatic endothelial cells (LECs) were shown to produce IL-7 and to express the IL-7 receptor chains, namely the interleukin-7 receptor alpha (IL-7Rα) and the common receptor gamma chain (CD132). IL-7 was able to activate human lymphatic endothelial cells in vitro and to induce lymphangiogenesis in vivo. Furthermore, the lymphatic network and function were greatly affected in IL-7Rα-/- and IL-7 transgenic mice. Functional drainage assays revealed that genetic overexpression of IL-7 or exogenous application of recombinant IL-7/anti-IL-7 complexes to WT mice markedly improved the drainage of a lymphatic specific dye from dermal lymphatics. Moreover, the use of bone marrow chimeras indicated that the drainage enhancing effect of IL-7 was dependent on IL-7 receptor expression in stromal cells rather than bone marrow derived cells. Intravital imaging experiments revealed that the pumping rate of the collecting lymphatics remained unchanged in the IL-7Rα-/- mice compared to WT mice, whereas increased leakage of dye from the lymphatic capillaries was observed. We are currently investigating the mechanism by which IL-7 enhances drainage by performing intravital contractility studies and ex vivo analyses of the lymphatic capillaries and collectors in IL-7Rα-/- mice. Furthermore, we are exploring whether the drainage enhancing effect of IL-7 can be used to treat diseases characterized by lymphatic drainage dysfunction, such as lymphedema and chronic skin inflammation. To this end we have created a murine IL-7-Fc fusion protein to extend the half-life of IL-7 in mice, making it suitable for therapy experiments.
CCL21 EXPRESSION PATTERN IN LYMPHATIC VESSELS
ERICA RUSSO, JORGE ARASA, CORNELIA HALIN
ETH Zurich, Institute of Pharmaceutical Sciences, HCI G490, Vladimir-Prelog-Weg 1-5/10, CH-8093 Zurich, Switzerland Email: jorge.arasa@pharma.ethz.ch
Adaptive immune responses are essential for conferring protection against infections and for promoting immune tolerance. They are initiated by the migration of leukocytes, particularly dendritic cells (DCs), through afferent lymphatic vessels (LVs) to draining lymph nodes (dLNs). Nevertheless, to date, DC migration into and within LVs remains poorly understood. In this sense, it has recently been described that DCs actively crawl within lymphatic capillaries and only passively transported once they reach the downstream-located segments of collecting LVs. The DCs migration into the LVs is mainly mediated by CCL21, a chemokine constitutively expressed by the lymphatic endothelium; however, CCL21 expression pattern along the LVs is still under discussion.
The aim of this work is to further investigate the expression of CCL21 in the capillaries and collectors of murine ear skin. For this purpose, we have established a new 5-color FACS staining approach that allows us to isolate lymphatic endothelial cells from the collectors (colLECs: CD45-, CD31+, podoplanin+, lyve1-) and capillaries (capLECs: CD45-, CD31+, podoplanin+, lyve1+). Thereby, we have found significant differences in the protein expression pattern, as well as in the mRNA expression of CCL21 between capillaries and collectors LVs. Furthermore, these results have been confirmed by whole mounts immunofluorescence where we detected a strong predominant expression of CCL21 in podoplanin+LYVE1+ capillaries.
Overall, our findings shed light on the expression pattern of this chemokine along the LVs and is prompting to further understand DCs migration across the LVs.
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THE EUROPEAN JOURNAL OF LYMPHOLOGY - Vol. XXVI - Nr. 72 - 2015