title: Dysfunctional blood and target tissue CD4+CD25high regulatory T cells in psoriasis: mechanism underlying unrestrained pathogenic effector T cell proliferation.
abstract: The balance between regulatory and effector functions is important for maintaining efficient immune responses, while avoiding autoimmunity. The inflammatory skin disease psoriasis is sustained by the ongoing activation of pathogenic effector T cells. We found that a CD4(+) T lymphocyte subpopulation in peripheral blood, phenotypically CD25(high), CTLA-4(+), Foxp3(high) (regulatory T (Treg) cells), is deficient in its suppressor activity in psoriasis. This was associated with accelerated proliferation of CD4(+) responder T cells in psoriasis, the majority of which expressed CXCR3. Nevertheless, criss-cross experiments isolated the defect to psoriatic Treg cells. To examine Treg cells in a nonlymphoid tissue of a human T cell-mediated disease, Treg cells were also analyzed and isolated from the site of inflammation, psoriatic lesional skin. At the regulatory vs effector T cells ratios calculated to be present in skin, however, the psoriatic Treg cell population demonstrated decreased suppression of effector T cells. Thus, dysfunctional blood and target tissue CD4(+)CD25(high) Treg cell activity may lead to reduced restraint and consequent hyperproliferation of psoriatic pathogenic T cells in vivo. These findings represent a critical component of human organ-specific autoimmune disease and may have important implications with regard to the possible therapeutic manipulation of Treg cells in vivo.
authors.affiliation: Department of Dermatology, University Hospitals of Cleveland and Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Sugiyama
authors.forename: Rolland
authors.initials: R
authors.lastname: Gyulai
authors.forename: Eiko
authors.initials: E
authors.lastname: Toichi
authors.forename: Edina
authors.initials: E
authors.lastname: Garaczi
authors.forename: Shinji
authors.initials: S
authors.lastname: Shimada
authors.forename: Seth R
authors.initials: SR
authors.lastname: Stevens
authors.forename: Thomas S
authors.initials: TS
authors.lastname: McCormick
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Cooper
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000276:immunology; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors; D006801:Humans; D011565:Psoriasis / Q000097:blood / Q000276:immunology*; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine / Q000276:immunology; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000166:cytology / Q000276:immunology* / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: C515187:CXCR3 protein, human; D004268:DNA-Binding Proteins; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine; D015375:Receptors, Interleukin-2