Postnatal Deletion of Podoplanin in Lymphatic Endothelium Results in Blood Filling of the Lymphatic System and Impairs Dendritic Cell Migration to Lymph Nodes.
The lymphatic vascular system exerts major physiological functions in the transport of interstitial fluid from peripheral tissues back to the blood circulation and in the trafficking of immune cells to lymph nodes. Previous studies in global constitutive knockout mice for the lymphatic transmembrane molecule podoplanin reported perinatal lethality and a complex phenotype with lung abnormalities, cardiac defects, lymphedema, blood-filled lymphatic vessels, and lack of lymph node organization, reflecting the importance of podoplanin expression not only by the lymphatic endothelium but also by a variety of nonendothelial cell types. Therefore, we aimed to dissect the specific role of podoplanin expressed by adult lymphatic vessels.



We generated an inducible, lymphatic-specific podoplanin knockout mouse model (PdpnΔLEC) and induced gene deletion postnatally. PdpnΔLECmice were viable, and their lymphatic vessels appeared morphologically normal with unaltered fluid drainage function. Intriguingly, PdpnΔLECmice had blood-filled lymph nodes and vessels, most frequently in the neck and axillary region, and displayed a blood-filled thoracic duct, suggestive of retrograde filling of blood from the blood circulation into the lymphatic system. Histological and fluorescence-activated cell sorter analyses revealed normal lymph node organization with the presence of erythrocytes within lymph node lymphatic vessels but not surrounding high endothelial venules. Moreover, fluorescein isothiocyanate painting experiments revealed reduced dendritic cell migration to lymph nodes in PdpnΔLECmice.



These results reveal an important role of podoplanin expressed by lymphatic vessels in preventing postnatal blood filling of the lymphatic vascular system and in contributing to efficient dendritic cell migration to the lymph nodes.
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Roberta
R
Bianchi
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Erica
E
Russo
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Samia B
SB
Bachmann
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Steven T
ST
Proulx
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Marko
M
Sesartic
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Nora
N
Smaadahl
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Steve P
SP
Watson
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Christopher D
CD
Buckley
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom.
Cornelia
C
Halin
From the Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zurich, Switzerland (R.B., E.R., S.B.B., S.T.P., M.S., N.S., C.H., M.D.); Centre for Cardiovascular Sciences, College of Medical and Dental Sciences (S.P.W.) and Rheumatology Research Group, Institute for Biomedical Research, College of Medical and Dental Sciences (C.D.B.), University of Birmingham, United Kingdom. michael.detmar@pharma.ethz.ch.
Michael
M
Detmar
D000818:Animals; D001775:Blood Circulation; D019521:Body Patterning; D002465:Cell Movement; D003713:Dendritic Cells / Q000378:metabolism* / Q000473:pathology; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D004729:Endothelium, Lymphatic / Q000378:metabolism* / Q000473:pathology; D004912:Erythrocytes / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D008198:Lymph Nodes / Q000378:metabolism* / Q000473:pathology; D042583:Lymphangiogenesis; D008562:Membrane Glycoproteins / Q000172:deficiency* / Q000235:genetics; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D015398:Signal Transduction; D013897:Thoracic Duct / Q000378:metabolism* / Q000473:pathology; D000098853:Podoplanin
D008562:Membrane Glycoproteins; C490441:Pdpn protein, mouse; D000098853:Podoplanin
endothelium, lymphatic; fluorescein-5-isothiocyanate; lymph nodes; models, animal; thoracic duct