CXCL10+ perivascular clusters nucleate Th1 cell tissue entry and activation in the inflamed skin

• Published in: The Journal of immunology (1950) 2020-05, Vol.204 (1_Supplement), p.220-220.9
• Main Authors: Prizant, Hen, Patil, Nilesh, Negatu, Seble, Livingston, Alexandra, Leddon, Scott, Luster, Andrew D, Fowell, Deborah J
• Format: Article
• Language: English
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.204.Supp.220.9

Efficient recruitment and correct positioning of T cells within infected peripheral tissues are crucial for pathogen clearance. Using a dual-chemokine reporter (Groom et Al. Immunity, 2012) mouse and intra-vital imaging, we identified a preferred tissue entry and accumulation site for effector Th1 cells, defined by clusters of CXCL9 and CXCL10 expressing hematopoietic cells, enriched with MHC-class-II+ cells, in restricted perivascular spaces within the inflamed dermis. Unbiased computational analysis of motility dynamics of antigen-specific Th1 cells within these clusters, revealed cell confinement characteristics. CXCR3 on Th1 cells and presence of cognate antigen were critical for persistence within clusters and T cell activation. Newly recruited Th1 cells strongly amplified CXCL9 and CXCL10 expression, mainly within skin monocyte-derived dendritic cells, in an antigen- and interferon-gamma-dependent manner, resulting in augmented chemokine clusters. Our data suggest a CXCR3-mediated mechanism of intrinsic amplification loop for optimal Th1 cell recruitment, positioning and activation in restricted antigen presentation sites within the inflamed skin.