ABSTRACT
Group 2 innate lymphoid cells (ILC2) are effectors of barrier immunity, with roles in infection, wound healing, and allergy. A proportion of ILC2 express MHCII (major histocompatibility complex II) and are capable of presenting peptide antigens to T cells and amplifying the subsequent adaptive immune response. Recent studies have highlighted the importance of CD1a-reactive T cells in allergy and infection, activated by the presentation of endogenous neolipid antigens and bacterial components. Using a human skin challenge model, we unexpectedly show that human skin-derived ILC2 can express CD1a and are capable of presenting endogenous antigens to T cells. CD1a expression is up-regulated by TSLP (thymic stromal lymphopoietin) at levels observed in the skin of patients with atopic dermatitis, and the response is dependent on PLA2G4A. Furthermore, this pathway is used to sense Staphylococcus aureus by promoting Toll-like receptor-dependent CD1a-reactive T cell responses to endogenous ligands. These findings define a previously unrecognized role for ILC2 in lipid surveillance and identify shared pathways of CD1a- and PLA2G4A-dependent ILC2 inflammation amenable to therapeutic intervention.
Subject(s)
Antigen Presentation/immunology , Antigens, CD1/genetics , Hypersensitivity , Immunity, Innate , Lymphocytes/immunology , Adult , Antigens, CD1/immunology , Biopsy , Cytokines/genetics , Cytokines/immunology , Dermatitis, Atopic/immunology , Female , Group IV Phospholipases A2/genetics , Group IV Phospholipases A2/immunology , Human Experimentation , Humans , Inflammation/immunology , Lipids/immunology , Male , Signal Transduction/immunology , Skin/cytology , Skin/immunology , Skin/pathology , Staphylococcus aureus/immunology , T-Lymphocytes/immunology , Toll-Like Receptors/immunology , Thymic Stromal LymphopoietinABSTRACT
The production of recombinant integral membrane proteins for structural and functional studies remains technically challenging due to their relatively low levels of expression. To address this problem, screening strategies have been developed to identify the optimal membrane sequence and expression host for protein production. A common approach is to genetically fuse the membrane protein to a fluorescent reporter, typically Green Fluorescent Protein (GFP) enabling expression levels, localization and detergent solubilisation to be assessed. Initially developed for screening the heterologous expression of bacterial membrane proteins in Escherichia coli, the method has been extended to eukaryotic hosts, including insect and mammalian cells. Overall, GFP-based expression screening has made a major impact on the number of membrane protein structures that have been determined in the last few years.
