title: Colitogenic CD4+ effector-memory T cells actively recirculate in chronic colitic mice.
abstract: BACKGROUND
  Although the clinical usefulness of leukocytapheresis for patients with inflammatory bowel disease (IBD) has been reported as a selective removal therapy targeting pathogenic immune cells in blood circulation, it remains unclear whether colitogenic CD4(+) T cells continuously recirculate in peripheral blood during the chronic phase of colitis.
  
  
  METHODS
  To resolve this question we conducted a series of in vivo experiments using a murine chronic colitis model induced by adoptive transfer of CD4(+)CD45RB(high) cells into SCID mice in combination with a parabiosis system.
  
  
  RESULTS
  In colitic SCID recipients, first, almost all CD4(+) CD45RB(high) donor cells were converted to CD4(+)CD44(high)CD62L(-) IL-7Ralpha(high) effector-memory T (T(EM)) cells at 8 weeks after transfer and were distributed throughout the whole body, including colonic lamina propria, mesenteric lymph nodes, thoracic duct, peripheral blood, spleen, and bone marrow. Second, SCID mice retransferred with the colitic peripheral blood CD4(+) T cells developed colitis that is identical to the original colitis. Third, CD4(+) cells in parabionts between established colitic RAG-2(-/-) mice induced by adoptive transfer of Ly5.1(+) or Ly5.2(+) CD4(+)CD45RB(high) T cells were well mixed in almost equal proportions at various sites 2 weeks after parabiosis surgery, and the redistribution of Ly5.1(+) and Ly5.2(+) CD4(+) T cells was significantly suppressed in FTY720-treated parabionts.
  
  
  CONCLUSIONS
  Together, these findings indicate that colitogenic CD4(+) T(EM) cells continuously recirculate in established colitic mice, suggesting that therapeutic approaches targeting systemic CD4(+) T(EM) cells, such as bone marrow transplantation, rather than those targeting only intestinal CD4(+) T cells, may be feasible for the treatment of IBD.
authors.affiliation: Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tomita
authors.forename: Takanori
authors.initials: T
authors.lastname: Kanai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nemoto
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Fujii
authors.forename: Kengo
authors.initials: K
authors.lastname: Nozaki
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okamoto
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nakamura
authors.forename: Naoya
authors.initials: N
authors.lastname: Sakamoto
authors.forename: Teruji
authors.initials: T
authors.lastname: Totsuka
authors.forename: Mamoru
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000637:transplantation; D002908:Chronic Disease; D003092:Colitis / Q000276:immunology* / Q000473:pathology; D003106:Colon / Q000276:immunology* / Q000473:pathology; D004268:DNA-Binding Proteins / Q000502:physiology; D005434:Flow Cytometry; D018960:Hyaluronan Receptors / Q000276:immunology; D007156:Immunologic Memory; D019041:L-Selectin / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D020395:Receptors, Interleukin-7 / Q000276:immunology
chemical_list: D004268:DNA-Binding Proteins; D018960:Hyaluronan Receptors; C499308:Rag2 protein, mouse; D020395:Receptors, Interleukin-7; C415350:interleukin-7 receptor, alpha chain; D019041:L-Selectin