Constitutive plasmacytoid dendritic cell migration to the splenic white pulp is cooperatively regulated by CCR7- and CXCR4-mediated signaling.
Although the spleen plays an important role in host defense against infection, the mechanism underlying the migration of the innate immune cells, plasmacytoid dendritic cells (pDCs), into the spleen remains ill defined. In this article, we report that pDCs constitutively migrate into the splenic white pulp (WP) in a manner dependent on the chemokine receptors CCR7 and CXCR4. In CCR7-deficient mice and CCR7 ligand-deficient mice, compared with wild-type (WT) mice, substantially fewer pDCs were found in the periarteriolar lymphoid sheath of the splenic WP under steady-state conditions. In addition, the migration of adoptively transferred CCR7-deficient pDCs into the WP was significantly worse than that of WT pDCs, supporting the idea that pDC trafficking to the splenic WP requires CCR7 signaling. WT pDCs responded to a CCR7 ligand with modest chemotaxis and ICAM-1 binding in vitro, and priming with the CCR7 ligand enabled the pDCs to migrate efficiently toward low concentrations of CXCL12 in a CXCR4-dependent manner, raising the possibility that CCR7 signaling enhances CXCR4-mediated pDC migration. In agreement with this hypothesis, CCL21 and CXCL12 were colocalized on fibroblastic reticular cells in the T cell zone and in the marginal zone bridging channels, through which pDCs appeared to enter the WP. Furthermore, functional blockage of CCR7 and CXCR4 abrogated pDC trafficking into the WP. Collectively, these results strongly suggest that pDCs employ both CCR7 and CXCR4 as critical chemokine receptors to migrate into the WP under steady-state conditions.
Laboratory of Immunodynamics, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, Suita 565-0871, Japan.
Eiji
E
Umemoto
Kazuhiro
K
Otani
Takashi
T
Ikeno
Noel
N
Verjan Garcia
Haruko
H
Hayasaka
Zhongbin
Z
Bai
Myoung Ho
MH
Jang
Toshiyuki
T
Tanaka
Takashi
T
Nagasawa
Koichi
K
Ueda
Masayuki
M
Miyasaka
D000818:Animals; D002465:Cell Movement / Q000235:genetics / Q000276:immunology*; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D054400:Receptors, CCR7 / Q000502:physiology*; D019718:Receptors, CXCR4 / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
C515370:CCR7 protein, human; C527276:CXCR4 protein, human; C514936:CXCR4 protein, mouse; C515371:Ccr7 protein, mouse; D054400:Receptors, CCR7; D019718:Receptors, CXCR4