Targeting lymphatic vessel activation and CCL21 production by vascular endothelial growth factor receptor-3 inhibition has novel immunomodulatory and antiarteriosclerotic effects in cardiac allografts.
BACKGROUND
Lymphatic network and chemokine-mediated signals are essential for leukocyte traffic during the proximal steps of alloimmune response. We aimed to determine the role of lymphatic vessels and their principal growth signaling pathway, vascular endothelial growth factor (VEGF)-C/D/VEGFR-3, during acute and chronic rejection in cardiac allografts.


RESULTS
Analysis of heterotopically transplanted rat cardiac allografts showed that chronic rejection increased VEGF-C(+) inflammatory cell and hyaluronan receptor-1 (LYVE-1)(+) lymphatic vessel density. Allograft lymphatic vessels were VEGFR-3(+), contained antigen-presenting cells, and produced dendritic cell chemokine CCL21. Experiments with VEGFR-3/LacZ mice or mice with green fluorescent protein-positive bone marrow cells as cardiac allograft recipients showed that allograft lymphatic vessels originated almost exclusively from donor cells. Intraportal adenoviral VEGFR-3-Ig (Ad.VEGFR-3-Ig/VEGF-C/D-Trap) perfusion was used to inhibit VEGF-C/D/VEGFR-3 signaling. Recipient treatment with Ad.VEGFR-3-Ig prolonged rat cardiac allograft survival. Ad.VEGFR-3-Ig did not affect allograft lymphangiogenesis but was linked to reduced CCL21 production and CD8(+) effector cell entry in the allograft. Concomitantly, Ad.VEGFR-3-Ig reduced OX62(+) dendritic cell recruitment and increased transcription factor Foxp3 expression in the spleen. In separate experiments, treatment with a neutralizing monoclonal VEGFR-3 antibody reduced arteriosclerosis, the number of activated lymphatic vessels expressing VEGFR-3 and CCL21, and graft-infiltrating CD4(+) T cells in chronically rejecting mouse cardiac allografts.


CONCLUSIONS
These results show that VEGFR-3 participates in immune cell traffic from peripheral tissues to secondary lymphoid organs by regulating allograft lymphatic vessel CCL21 production and suggest VEGFR-3 inhibition as a novel lymphatic vessel-targeted immunomodulatory therapy for cardiac allograft rejection and arteriosclerosis.
Nykänen
Antti I
AI
Cardiopulmonary Research Group, Transplantation Laboratory, Haartman Institute, FI-00014 University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland. Antti.Nykanen@Helsinki.Fi
Sandelin
Henrik
H
Krebs
Rainer
R
Keränen
Mikko A I
MA
Tuuminen
Raimo
R
Kärpänen
Terhi
T
Wu
Yan
Y
Pytowski
Bronislaw
B
Koskinen
Petri K
PK
Ylä-Herttuala
Seppo
S
Alitalo
Kari
K
Lemström
Karl B
KB
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology / Q000627:therapeutic use; D000938:Antigen-Presenting Cells; D001161:Arteriosclerosis / Q000188:drug therapy / Q000517:prevention & control*; D002465:Cell Movement / Q000276:immunology; D054421:Chemokine CCL21 / Q000096:biosynthesis*; D006084:Graft Rejection / Q000276:immunology; D016027:Heart Transplantation / Q000276:immunology*; D056747:Immunomodulation / Q000187:drug effects*; D042601:Lymphatic Vessels / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D051381:Rats; D015398:Signal Transduction / Q000276:immunology; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000037:antagonists & inhibitors* / Q000276:immunology
D000911:Antibodies, Monoclonal; C515478:CCL21 protein, human; D054421:Chemokine CCL21; D040321:Vascular Endothelial Growth Factor Receptor-3