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Psoriasis and the MAITing game: a role for IL-17A+ invariant TCR CD8+ T cells in psoriasis?

Johnston A, Gudjonsson JE - J. Invest. Dermatol. (2014)

Bottom Line: Recent findings have indicated that the majority of IL-17A+ CD8+ T cells in the blood belong to a subset of innate T cells named mucosa-associated invariant T cells (MAITs).In this issue, Teunissen and colleagues (2014) demonstrate that, although MAIT cells are found in psoriatic skin, they are not increased in abundance and that the majority of IL-17A+CD8+ T cells in plaques of psoriasis are devoid of MAIT cell characteristics.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, University of Michigan, Ann Arbor, Michigan, USA.

ABSTRACT
Recent findings have indicated that the majority of IL-17A+ CD8+ T cells in the blood belong to a subset of innate T cells named mucosa-associated invariant T cells (MAITs). In this issue, Teunissen and colleagues (2014) demonstrate that, although MAIT cells are found in psoriatic skin, they are not increased in abundance and that the majority of IL-17A+CD8+ T cells in plaques of psoriasis are devoid of MAIT cell characteristics.

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Mucosa-associated invariant T-cells (MAIT) join the ranks of the unconventional T-cellsCharacterized by their limited TCR rearrangements, unconventional T-cells respond more quickly than their conventional counterparts, stationed in peripheral tissues poised to act. These cells expand the repertoire of antigens recognized by T-cells; with the invariant natural killer (iNK) T-cells responding to lipid antigens presented by CD1d, and several clones of γδ T-cells recognizing a diverse array of structures including phospho-antigens and sphingolipids apparently independent of MHC-antigen presentation. Like conventional αβ T-cells and, MAIT cells recognize antigens presented in the context of an MHC-like molecule, MR1, on the surface of antigen presenting cells (green) or epithelia (brown). Thus far, antigens derived from the structures of vitamins B2 and B9 containing a ribityl carbohydrate group have been identified to activate MAIT cells. MAIT cells express many of the markers associated with Th17 cells (RORC, CD161, CCR6) and account for the majority of IL17-producing CD8+ T-cells in the blood, but only a fraction of epidermal IL-17+CD8+ cells.
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Figure 1: Mucosa-associated invariant T-cells (MAIT) join the ranks of the unconventional T-cellsCharacterized by their limited TCR rearrangements, unconventional T-cells respond more quickly than their conventional counterparts, stationed in peripheral tissues poised to act. These cells expand the repertoire of antigens recognized by T-cells; with the invariant natural killer (iNK) T-cells responding to lipid antigens presented by CD1d, and several clones of γδ T-cells recognizing a diverse array of structures including phospho-antigens and sphingolipids apparently independent of MHC-antigen presentation. Like conventional αβ T-cells and, MAIT cells recognize antigens presented in the context of an MHC-like molecule, MR1, on the surface of antigen presenting cells (green) or epithelia (brown). Thus far, antigens derived from the structures of vitamins B2 and B9 containing a ribityl carbohydrate group have been identified to activate MAIT cells. MAIT cells express many of the markers associated with Th17 cells (RORC, CD161, CCR6) and account for the majority of IL17-producing CD8+ T-cells in the blood, but only a fraction of epidermal IL-17+CD8+ cells.

Mentions: Mucosa-associated invariant T-cells (MAIT) are a recently-characterized T-cell subset that together with γδ T-cells and invariant natural killer T-cells (iNKT) joins the ranks of the unconventional T-cells (Figure 1). Like other subsets of innate T-cells (Laggner et al., 2011), attempts have been made to implicate these cells in the pathogenesis of psoriasis (Bonish et al., 2000), especially because IL-17 is now known to have a prominent role in the pathogenesis of psoriasis, and because MAIT cells have been shown to account for the majority of the IL-17A-producing CD8+ T-cells in the blood (Dusseaux et al., 2011). In their article, Teunissen and colleagues (Teunissen et al., 2014) show that while the number of IL-17A-producing CD8+ T-cells in the blood correlates with psoriasis disease severity and while MAIT cells are found in psoriatic skin, they are not increased in frequency compared with normal skin; moreover a large proportion of the IL-17A-producing CD8+ T-cells in skin plaques are conventional CD8+ T-cells.


Psoriasis and the MAITing game: a role for IL-17A+ invariant TCR CD8+ T cells in psoriasis?

Johnston A, Gudjonsson JE - J. Invest. Dermatol. (2014)

Mucosa-associated invariant T-cells (MAIT) join the ranks of the unconventional T-cellsCharacterized by their limited TCR rearrangements, unconventional T-cells respond more quickly than their conventional counterparts, stationed in peripheral tissues poised to act. These cells expand the repertoire of antigens recognized by T-cells; with the invariant natural killer (iNK) T-cells responding to lipid antigens presented by CD1d, and several clones of γδ T-cells recognizing a diverse array of structures including phospho-antigens and sphingolipids apparently independent of MHC-antigen presentation. Like conventional αβ T-cells and, MAIT cells recognize antigens presented in the context of an MHC-like molecule, MR1, on the surface of antigen presenting cells (green) or epithelia (brown). Thus far, antigens derived from the structures of vitamins B2 and B9 containing a ribityl carbohydrate group have been identified to activate MAIT cells. MAIT cells express many of the markers associated with Th17 cells (RORC, CD161, CCR6) and account for the majority of IL17-producing CD8+ T-cells in the blood, but only a fraction of epidermal IL-17+CD8+ cells.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4228793&req=5

Figure 1: Mucosa-associated invariant T-cells (MAIT) join the ranks of the unconventional T-cellsCharacterized by their limited TCR rearrangements, unconventional T-cells respond more quickly than their conventional counterparts, stationed in peripheral tissues poised to act. These cells expand the repertoire of antigens recognized by T-cells; with the invariant natural killer (iNK) T-cells responding to lipid antigens presented by CD1d, and several clones of γδ T-cells recognizing a diverse array of structures including phospho-antigens and sphingolipids apparently independent of MHC-antigen presentation. Like conventional αβ T-cells and, MAIT cells recognize antigens presented in the context of an MHC-like molecule, MR1, on the surface of antigen presenting cells (green) or epithelia (brown). Thus far, antigens derived from the structures of vitamins B2 and B9 containing a ribityl carbohydrate group have been identified to activate MAIT cells. MAIT cells express many of the markers associated with Th17 cells (RORC, CD161, CCR6) and account for the majority of IL17-producing CD8+ T-cells in the blood, but only a fraction of epidermal IL-17+CD8+ cells.
Mentions: Mucosa-associated invariant T-cells (MAIT) are a recently-characterized T-cell subset that together with γδ T-cells and invariant natural killer T-cells (iNKT) joins the ranks of the unconventional T-cells (Figure 1). Like other subsets of innate T-cells (Laggner et al., 2011), attempts have been made to implicate these cells in the pathogenesis of psoriasis (Bonish et al., 2000), especially because IL-17 is now known to have a prominent role in the pathogenesis of psoriasis, and because MAIT cells have been shown to account for the majority of the IL-17A-producing CD8+ T-cells in the blood (Dusseaux et al., 2011). In their article, Teunissen and colleagues (Teunissen et al., 2014) show that while the number of IL-17A-producing CD8+ T-cells in the blood correlates with psoriasis disease severity and while MAIT cells are found in psoriatic skin, they are not increased in frequency compared with normal skin; moreover a large proportion of the IL-17A-producing CD8+ T-cells in skin plaques are conventional CD8+ T-cells.

Bottom Line: Recent findings have indicated that the majority of IL-17A+ CD8+ T cells in the blood belong to a subset of innate T cells named mucosa-associated invariant T cells (MAITs).In this issue, Teunissen and colleagues (2014) demonstrate that, although MAIT cells are found in psoriatic skin, they are not increased in abundance and that the majority of IL-17A+CD8+ T cells in plaques of psoriasis are devoid of MAIT cell characteristics.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, University of Michigan, Ann Arbor, Michigan, USA.

ABSTRACT
Recent findings have indicated that the majority of IL-17A+ CD8+ T cells in the blood belong to a subset of innate T cells named mucosa-associated invariant T cells (MAITs). In this issue, Teunissen and colleagues (2014) demonstrate that, although MAIT cells are found in psoriatic skin, they are not increased in abundance and that the majority of IL-17A+CD8+ T cells in plaques of psoriasis are devoid of MAIT cell characteristics.

Show MeSH
Related in: MedlinePlus