title: Graft Site Microenvironment Determines Dendritic Cell Trafficking Through the CCR7-CCL19/21 Axis.
abstract: OBJECTIVE
  The graft site microenvironment has a profound effect on alloimmunity and graft survival. We aimed to study the kinetics and phenotype of trafficking antigen-presenting cells (APC) to the draining lymph nodes (DLNs) in a mouse model of corneal transplantation, and to evaluate the homing mechanisms through which graft site inflammation controls APC trafficking.
  
  
  METHODS
  Allogeneic donor corneas were transplanted onto inflamed or quiescent graft beds. Host- (YAe+) and donor (CD45.1+ or eGFP+)-derived APCs were analyzed by flow cytometry. Protein and mRNA expression of the CC chemokine receptor (CCR)7 ligands CCL19 and CCL21 were assessed using ELISA and Real-Time qPCR, respectively. Transwell migration assay was performed to assess the effect of DLNs isolated from hosts with inflamed graft beds on mature bone marrow-derived dendritic cells (BMDCs).
  
  
  RESULTS
  We found that inflamed graft sites greatly promote the trafficking of both recipient- and graft-derived APCs, in particular mature CCR7+ CD11c+ dendritic cells (DC). CCL19 and CCL21 were expressed at significantly higher levels in the DLNs of recipients with inflamed graft beds. The supernatant of DLNs from recipients with inflamed graft beds induced a marked increase in mature DC migration compared with supernatant from recipients with quiescent graft beds in a transwell assay. This effect was abolished by neutralizing CCL19 or CCL21. These data suggest that graft site inflammation increases the expression of CCR7 ligands in the DLNs, which promote mature DC homing and allorejection.
  
  
  CONCLUSIONS
  We conclude that the graft site microenvironment plays a critical role in alloimmunity by determining DC trafficking through the CCR7-CCL19/21 axis.
authors.forename: Jing
authors.initials: J
authors.lastname: Hua
authors.forename: William
authors.initials: W
authors.lastname: Stevenson
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Dohlman
authors.forename: Takenori
authors.initials: T
authors.lastname: Inomata
authors.forename: Maryam
authors.initials: M
authors.lastname: Tahvildari
authors.forename: Narghes
authors.initials: N
authors.lastname: Calcagno
authors.forename: Negar
authors.initials: N
authors.lastname: Pirmadjid
authors.forename: Zahra
authors.initials: Z
authors.lastname: Sadrai
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Chauhan
authors.forename: Reza
authors.initials: R
authors.lastname: Dana
mesh_terms: D000818:Animals; D002465:Cell Movement; D002478:Cells, Cultured; D054415:Chemokine CCL19 / Q000096:biosynthesis / Q000235:genetics*; D054421:Chemokine CCL21 / Q000096:biosynthesis / Q000235:genetics*; D016039:Corneal Transplantation; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006085:Graft Survival / Q000235:genetics*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D012313:RNA / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D054400:Receptors, CCR7 / Q000096:biosynthesis / Q000235:genetics*
chemical_list: C515461:Ccl19 protein, mouse; D054415:Chemokine CCL19; D054421:Chemokine CCL21; D054400:Receptors, CCR7; D012313:RNA