engleski

Immunostaining of MAIT and γδT cells in psoriatic lesions

Psoriasis vulgaris (PV) is a common, chronic inflammatory skin disease driven by aberrant activation of T cells. In addition to autoreactive conventional T cell lines, innate-like lymphocytes, such as MAIT (mucosal associated invariant T cells) and γ δT cells, have been recently implicated in the initiation and progression of PV. Both MAIT and γ δT lymphocytes seed multiple epithelial tissues and demonstrate various functional capacities in host tissue repair, pathogen clearance, tumor surveillance, and inflammation. In case of injury or antigen encounter in the skin, these innate-like players exhibit rapid effector responses and directly contribute to local IL-17 production, a key pro- inflammatory mediator of epithelial, stromal, and vascular remodeling in psoriasis. Emerging evidence suggest an important role for MAIT and γ δT cells in PV immunopathology, but their diversity, distribution and trafficking in psoriatic skin plaques remain less well understood. To determine the number and distribution of IL-17-producing MAIT and γδT cells in psoriatic and healthy skin, a multiplex immunofluorescence analysis was performed with MR1 5-OP-RU PEconjugated tetramer in combination with primary monoclonal antibodies against CD3, IL-17A and γ δTCR. Psoriatic (n=6) and healthy (n=3) skin biopsies were initially fixed in 4% paraformaldehyde, cryoprotected in sucrose gradient and snap frozen, before being cut on the cryostat. Primary antibodies were detected with fluorescently labeled secondary antibodies, and nuclei stained with DAPI. All slides were covered with a VectaShield covering media and imaged under a fluorescent microscope. Compared to healthy skin, psoriatic skin sections were significantly enriched in CD3+ and IL-17+ T cells, of which only a minor fraction were either γ δTCR+ or MR1- restricted lymphocytes. Although rarely evident in examined skin sections, both MR1-tet+IL-17+ and γ δTCR+IL17+ T cells were more frequently observed in psoriatic sections, predominantly in dermal area, between elongated rete ridges of the epidermis. In conclusion, our results provide novel insights on MAIT and γδT cell distribution in healthy and psoriatic skin, and warrant further research on their phenotype and function in PV.

psoriasis, gamma-delta T cells, MAIT, immunostaining

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