title: IL-7 Is essential for the development and the persistence of chronic colitis.
abstract: Although IL-7 has recently emerged as a key cytokine involved in controlling the homeostatic turnover and the survival of peripheral resting memory CD4(+) T cells, its potential to be sustained pathogenic CD4(+) T cells in chronic immune diseases, such as inflammatory bowel diseases, still remains unclear. In this study, we demonstrate that IL-7 is essential for the development and the persistence of chronic colitis induced by adoptive transfer of normal CD4(+)CD45RB(high) T cells or colitogenic lamina propria (LP) CD4(+) memory T cells into immunodeficient IL-7(+/+) x RAG-1(-/-) and IL-7(-/-) x RAG-1(-/-) mice. Although IL-7(+/+) x RAG-1(-/-) recipients transferred with CD4(+)CD45RB(high) splenocytes developed massive inflammation of the large intestinal mucosa concurrent with massive expansion of Th1 cells, IL-7(-/-) x RAG-1(-/-) recipients did not. Furthermore, IL-7(-/-) x RAG-1(-/-), but not IL-7(+/+) x RAG-1(-/-), mice transferred with LP CD4(+)CD44(high)CD62L(-)IL-7Ralpha(high) effector-memory T cells (T(EM)) isolated from colitic CD4(+)CD45RB(high)-transferred mice did not develop colitis. Although rapid proliferation of transferred colitogenic LP CD4(+) T(EM) cells was observed in the in IL-7(-/-) x RAG-1(-/-) mice to a similar extent of those in IL-7(+/+) x RAG-1(-/-) mice, Bcl-2 expression was significantly down-modulated in the transferred CD4(+) T cells in IL-7(-/-) x RAG-1(-/-) mice compared with those in IL-7(+/+) x RAG-1(-/-) mice. Taken together, IL-7 is essential for the development and the persistence of chronic colitis as a critical survival factor for colitogenic CD4(+) T(EM) cells, suggesting that therapeutic approaches targeting IL-7/IL-7R signaling pathway may be feasible in the treatment of inflammatory bowel diseases.
authors.affiliation: Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Teruji
authors.initials: T
authors.lastname: Totsuka
authors.forename: Takanori
authors.initials: T
authors.lastname: Kanai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nemoto
authors.forename: Shin
authors.initials: S
authors.lastname: Makita
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okamoto
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Mamoru
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002908:Chronic Disease; D003092:Colitis / Q000209:etiology* / Q000276:immunology; D005260:Female; D018398:Homeodomain Proteins / Q000502:physiology; D015851:Interleukin-7 / Q000502:physiology; D017493:Leukocyte Common Antigens / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL; D020395:Receptors, Interleukin-7 / Q000032:analysis
chemical_list: D018398:Homeodomain Proteins; D015851:Interleukin-7; D020395:Receptors, Interleukin-7; C415350:interleukin-7 receptor, alpha chain; C064658:RAG-1 protein; D017493:Leukocyte Common Antigens