title: CCR7-mediated physiological lymphocyte homing involves activation of a tyrosine kinase pathway.
abstract: Homing of blood-borne lymphocytes to peripheral lymph nodes (PLNs) is a multistep process dependent on the sequential engagement of L-selectin, which mediates lymphocyte rolling along the luminal surface of high endothelial venules (HEVs), followed by activation of lymphocyte integrins and transmigration through HEVs. Within lymphoid tissue, B and T lymphocytes then migrate toward specific microenvironments such as B-cell follicles and the paracortex, respectively. The lymphocyte-expressed chemokine receptor CCR7 is playing an important role during this process, as its HEV-presented ligands CCL19 and CCL21 can trigger rapid integrin activation under flow in addition to inducing a chemotactic response, which may participate in transmigration and/or interstitial migration. Here, we report that Tyrphostin (Tyr) AG490, a pharmacological inhibitor of Janus family tyrosine kinases (Jaks), blocked the chemotactic response of primary mouse lymphocytes to CCL19 and CCL21 in a dose-dependent manner. Furthermore, Tyr AG490 inhibited rapid CCL21-mediated up-regulation of alpha4 and beta2 integrin adhesiveness in static adhesion assays and under physiological flow, whereas adhesion induced by phorbol myristate acetate remained unaltered. Using intravital microscopy of subiliac PLNs in mice, we found that adoptively transferred Tyr AG490-treated lymphocytes adhered significantly less in HEVs compared with control cells, although L-selectin-mediated rolling was similar in both samples. Finally, we observed rapid Jak2 phosphorylation in CCL21-stimulated primary mouse lymphocytes. Thus, our study suggests a role for Jak tyrosine kinases during CCR7-mediated lymphocyte recirculation.
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnologia/Consejo Superior de Investigaciones Cientificas (CSIC), Madrid, Spain. jstein@cnb.uam.es
authors.forename: Jens V
authors.initials: JV
authors.lastname: Stein
authors.forename: Silvia F
authors.initials: SF
authors.lastname: Soriano
authors.forename: Christine
authors.initials: C
authors.lastname: M'rini
authors.forename: César
authors.initials: C
authors.lastname: Nombela-Arrieta
authors.forename: Gonzalo González
authors.initials: GG
authors.lastname: de Buitrago
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Rodríguez-Frade
authors.forename: Mario
authors.initials: M
authors.lastname: Mellado
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Girard
authors.forename: Carlos
authors.initials: C
authors.lastname: Martínez-A
mesh_terms: D000818:Animals; D054415:Chemokine CCL19; D054421:Chemokine CCL21; D054377:Chemokine CXCL12; D019742:Chemokines, CC / Q000378:metabolism; D019743:Chemokines, CXC; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D016023:Integrins / Q000187:drug effects; D053614:Janus Kinase 2; D008198:Lymph Nodes / Q000098:blood supply / Q000166:cytology; D051379:Mice; D008807:Mice, Inbred BALB C; D008833:Microcirculation; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D054400:Receptors, CCR7; D019707:Receptors, Chemokine / Q000378:metabolism / Q000502:physiology*; D016201:Receptors, Lymphocyte Homing; D015398:Signal Transduction; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: C515461:Ccl19 protein, mouse; C515479:Ccl21c protein, mouse; C515371:Ccr7 protein, mouse; D054415:Chemokine CCL19; D054421:Chemokine CCL21; D054377:Chemokine CXCL12; D019742:Chemokines, CC; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D016023:Integrins; D011518:Proto-Oncogene Proteins; D054400:Receptors, CCR7; D019707:Receptors, Chemokine; D016201:Receptors, Lymphocyte Homing; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2