title: TNF Blockade Maintains an IL-10+Phenotype in Human Effector CD4+and CD8+T Cells.
abstract: CD4+and CD8+effector T cell subpopulations can display regulatory potential characterized by expression of the prototypically anti-inflammatory cytokine IL-10. However, the underlying cellular mechanisms that regulate expression of IL-10 in different T cell subpopulations are not yet fully elucidated. We recently showed that TNF inhibitors (TNFi) promote IL-10 expression in human CD4+T cells, including IL-17+CD4+T cells. Here, we further characterized the regulation of IL-10 expressionviablockade of TNF signaling or other cytokine/co-stimulatory pathways, in human T cell subpopulations. Addition of the TNFi drug adalimumab to anti-CD3-stimulated human CD4+T cell/monocyte cocultures led to increased percentages of IL-10+cells in pro-inflammatory IL-17+, IFNγ+, TNFα+, GM-CSF+, and IL-4+CD4+T cell subpopulations. Conversely, exogenous TNFα strongly decreased IL-10+cell frequencies. TNF blockade also regulated IL-10 expression in CD4+T cells upon antigenic stimulation. Using time course experiments in whole peripheral blood mononuclear cell (PBMC) cultures, we show that TNF blockade maintained, rather than increased, IL-10+cell frequencies in both CD4+and CD8+T cells followingin vitrostimulation in a dose- and time-dependent manner. Blockade of IL-17, IFNγ, IL-6R, or CD80/CD86-mediated co-stimulation did not significantly regulate IL-10 expression within CD4+or CD8+T cell subpopulations. We show that TNF blockade acts directly on effector CD4+T cells, in the absence of monocytes or CD4+CD25highCD127lowregulatory T cells and independently of IL-27, resulting in higher IL-10+frequencies after 3 days in culture. IL-10/IL-10R blockade reduced the frequency of IL-10-expressing cells both in the presence and absence of TNF blockade. Addition of recombinant IL-10 alone was insufficient to drive an increase in IL-10+CD4+T cell frequencies in 3-day CD4+T cell/monocyte cocultures, but resulted in increased IL-10 expression at later time points in whole PBMC cultures. Together, these data provide additional insights into the regulation of IL-10 expression in human T cells by TNF blockade. The maintenance of an IL-10+phenotype across a broad range of effector T cell subsets may represent an underappreciated mechanism of action underlying this widely used therapeutic strategy.
authors.affiliation: Division of Immunology, Infection and Inflammatory Disease (DIIID), Centre for Inflammation Biology and Cancer Immunology (CIBCI), King's College London , London , UK.
authors.forename: Ceri A
authors.initials: CA
authors.lastname: Roberts
authors.affiliation: Division of Immunology, Infection and Inflammatory Disease (DIIID), Centre for Inflammation Biology and Cancer Immunology (CIBCI), King's College London , London , UK.
authors.forename: Lucy E
authors.initials: LE
authors.lastname: Durham
authors.affiliation: Division of Immunology, Infection and Inflammatory Disease (DIIID), Centre for Inflammation Biology and Cancer Immunology (CIBCI), King's College London , London , UK.
authors.forename: Veerle
authors.initials: V
authors.lastname: Fleskens
authors.affiliation: Division of Immunology, Infection and Inflammatory Disease (DIIID), Centre for Inflammation Biology and Cancer Immunology (CIBCI), King's College London , London , UK.
authors.forename: Hayley G
authors.initials: HG
authors.lastname: Evans
authors.affiliation: Division of Immunology, Infection and Inflammatory Disease (DIIID), Centre for Inflammation Biology and Cancer Immunology (CIBCI), King's College London , London , UK.
authors.forename: Leonie S
authors.initials: LS
authors.lastname: Taams
keywords: CD4+ T cell polarization; CD8+ T cell polarization; IL-10 regulation; TNF inhibitors; adalimumab; anti-TNF; interleukin-10; tumor necrosis factor