title: CD4+ T-cell subsets in inflammatory diseases: beyond the Th1/Th2 paradigm.
abstract: CD4(+)T cells are crucial for directing appropriate immune responses during host defense and for the pathogenesis of inflammatory diseases. In addition to the classical biphasic model of differentiation of T-helper 1 (Th1) and Th2 cells, unexpected increases in the numbers of CD4(+)T-cell subsets, including Th17, Th9, T follicular-helper (Tfh) and T-regulatory (Treg) cells, have been recognized. In the present review, we focus on how these various T-helper cell subsets contribute to the pathogenesis of immune-mediated inflammatory diseases. In particular, we focus on multiple sclerosis, psoriasis and asthma as typical model diseases in which multiple T-helper cell subsets have recently been suggested to play a role. We will also discuss various unique sub-populations of T-helper cells that have been identified. First, we will introduce the heterogeneous T-helper cell subsets, which are classified by their simultaneous expression of multiple key transcription factors. We will also introduce different kinds of memory-type Th2 cells, which are involved in the pathogenesis of chronic type-2 immune-related diseases. Finally, we will discuss the molecular mechanisms underlying the generation of the plasticity and heterogeneity of T-helper cell subsets. The latest progress in the study of T-helper cell subsets has forced us to reconsider the etiology of immune-mediated inflammatory diseases beyond the model based on the Th1/Th2 balance. To this end, we propose another model--the pathogenic T-helper population disease-induction model--as a possible mechanism for the induction and/or persistence of immune-mediated inflammatory diseases.
authors.affiliation: Department of Advanced Allergology of the Airway, Graduate School of Medicine, Chiba University, 1-8-1 Inohana Chuo-ku, Chiba 260-8670, Japan Department of Immunology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Hirahara
authors.affiliation: Department of Immunology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana Chuo-ku, Chiba 260-8670, Japan AMED-CREST, The Japan Agency for Medical Research and Development (AMED), 1-8-1 Inohana Chuo-ku, Chiba 260-8670, Japan tnakayama@faculty.chiba-u.jp.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Nakayama
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D044127:Epigenesis, Genetic; D005786:Gene Expression Regulation; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory; D007249:Inflammation / Q000235:genetics / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism*; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism
keywords: T-cell plasticity; Th1/Th2 paradigm; epigenetics; memory Th2 cells; pathogenic Th2 (Tpath2) cells