Oligomerization of CXCL10 is necessary for endothelial cell presentation and in vivo activity.
The chemokine IFN-gamma-inducible protein of 10 kDa (IP-10; CXCL10) plays an important role in the recruitment of activated T lymphocytes into sites of inflammation by interacting with the G protein-coupled receptor CXCR3. IP-10, like other chemokines, forms oligomers, the role of which has not yet been explored. In this study, we used a monomeric IP-10 mutant to elucidate the functional significance of oligomerization. Although monomeric IP-10 had reduced binding affinity for CXCR3 and heparin, it was able to induce in vitro chemotaxis of activated T cells with the same efficacy as wild-type IP-10. However, monomeric IP-10 was unable to induce recruitment of activated CD8+ T cells into the airways of mice after intratracheal instillation. Use of a different IP-10 mutant demonstrated that this inability was due to lack of oligomerization rather than reduced CXCR3 or heparin binding. Molecular imaging demonstrated that both wild-type and monomeric IP-10 were retained in the lung after intratracheal instillation. However, in vitro binding assays indicated that wild-type, but not monomeric, IP-10 was retained on endothelial cells and could induce transendothelial chemotaxis of activated T cells. We therefore propose that oligomerization of IP-10 is required for presentation on endothelial cells and subsequent transendothelial migration, an essential step for lymphocyte recruitment in vivo.
Campanella
Gabriele S V
GS
Division of Rheumatology, Allergy, and Immunology, Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA.
Grimm
Jan
J
Manice
Lindsay A
LA
Colvin
Richard A
RA
Medoff
Benjamin D
BD
Wojtkiewicz
Gregory R
GR
Weissleder
Ralph
R
Luster
Andrew D
AD
D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000637:transplantation; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D054357:Chemokine CXCL10; D019743:Chemokines, CXC / Q000008:administration & dosage / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D002634:Chemotaxis, Leukocyte / Q000235:genetics / Q000276:immunology; D004527:Egg Proteins / Q000276:immunology / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D007442:Intubation, Intratracheal; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010047:Ovalbumin / Q000276:immunology / Q000378:metabolism; D010446:Peptide Fragments
D054357:Chemokine CXCL10; D019743:Chemokines, CXC; D004527:Egg Proteins; C110366:OVA-8; D010446:Peptide Fragments; D010047:Ovalbumin