title: Pathogenic Th cell subsets in chronic inflammatory diseases.
abstract: CD4(+) T cells play central roles to appropriate protection against pathogens. While, they can also be pathogenic driving inflammatory diseases. Besides the classical model of differentiation of T helper 1 (Th1) and Th2 cells, various CD4(+) T cell subsets, including Th17, Th9, T follicular helper (Tfh) and T regulatory (Treg) cells, have been recognized recently. In this review, we will focus on how these various CD4(+) T cell subsets contribute to the pathogenesis of immune-mediated inflammatory diseases. We will also discuss various unique subpopulations of T helper cells that have been identified. Recent advancement of the basic immunological research revealed that T helper cells are plastic than we imagined. So, we will focus on the molecular mechanisms underlying the generation of the plasticity and heterogeneity of T helper cell subsets. These latest finding regarding T helper cell subsets has pushed us to reconsider the etiology of immune-mediated inflammatory diseases beyond the model based on the conventional Th1/Th2 balance. Toward this end, we put forward another model, "the pathogenic Th population disease induction model", as a possible mechanism for the induction and/or persistence of immune-mediated inflammatory diseases.
authors.affiliation: Department of Immunology, Graduate School of Medicine, Chiba University.
authors.forename: Jin
authors.initials: J
authors.lastname: Kumagai
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Hirahara
authors.forename: Toshinori
authors.initials: T
authors.lastname: Nakayama
mesh_terms: D000818:Animals; D001249:Asthma / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000066670:Cell Plasticity; D002908:Chronic Disease; D006801:Humans; D007249:Inflammation / Q000276:immunology*; D016131:Lymphocyte Subsets / Q000276:immunology*; D051379:Mice; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D058408:Th1-Th2 Balance