Increased IL-17 production by peripheral T helper cells after tumour necrosis factor blockade in rheumatoid arthritis is accompanied by inhibition of migration-associated chemokine receptor expression.

OBJECTIVES: The contribution of IL-17-producing Th17 cells to the pathogenesis of T-cell-mediated inflammatory disorders such as RA and atopic dermatitis (AD) has to be viewed in relation to the role of Th1/Th2 cells and long-recognized key cytokines like TNF. We aimed to study the frequency and migration-associated phenotype of peripheral Th17, Th1 and Th2 cells in healthy individuals, RA and AD patients, and to study the influence of anti-TNF therapy in RA. METHODS: Intracellular IL-17, IFN-γ and IL-4 production and CC-chemokine receptor CCR4 and CCR6 expression were analysed flow cytometrically in peripheral memory Th cells from healthy individuals, AD and RA patients. The latter were grouped by disease activity and presence or absence of adalimumab therapy. In RA patients initiating anti-TNF therapy, cytokine production by in vitro-stimulated peripheral mononuclear cells was measured by cytometric bead array. RESULTS: The peripheral Th17 cell frequency is elevated in AD but not in RA. In RA, Th17 cells and IL-17 production increase after anti-TNF therapy, irrespective of disease activity. Th1 cells and IFN-γ production are elevated in remission and under anti-TNF therapy. CCR6 expression is up-regulated in Th17 cells, but RA patients in remission under anti-TNF therapy have significantly lower expression than those with active disease. CONCLUSIONS: The increase in peripheral Th17 cells in RA patients after anti-TNF therapy is accompanied by a decrease in Th17-specific CCR6 expression, which might prevent homing of these potentially pro-inflammatory cells to the synovium.

Flow cytometric analysis of phospho-p38 mitogen-activated kinase (MAPK): p38 MAPK does not mediate the effect of adalimumab on peripheral T cell cytokine production in rheumatoid arthritis.

BACKGROUND: The therapeutic effect of TNFalpha inhibition in rheumatoid arthritis (RA) is accompanied by an altered peripheral T cell cytokine profile, but the underlying mechanisms are not well known. In CD4+ T cells, TNF signalling includes the p38 MAP kinase (MAPK) pathway, which is also involved in proliferation and production of IL-4 and IFNgamma. METHODS: Phosphorylation of p38 MAPK was analysed flow cytometrically in peripheral blood mononuclear cells (PBMC) from healthy individuals and RA patients before and after adalimumab therapy. Cytokine production by CD3/CD28-stimulated PBMC was measured in the supernatant. RESULTS: Despite a transient activation of p38 MAPK in response to cellular stress from the cell separation, a significant decrease of spontaneous p38 MAPK phosphorylation was observed after adalimumab, compared to RA patients with active disease. Brief stimulation with TNFalpha/IL-1beta significantly activated p38 MAPK after but not before adalimumab therapy. In CD3/CD28-stimulated PBMC, significantly less p38 MAPK activation and increased IFNgamma production were observed after adalimumab therapy. CONCLUSION: In rheumatoid arthritis, adalimumab therapy decreases the phosphorylation of p38 MAPK except for its response to TNF/IL-1, while enhancing the production of IFNgamma. This suggests that p38 MAPK is not directly involved in the effect of TNF inhibition on cytokine production.

Simultaneous flow cytometric detection of basophil activation marker CD63 and intracellular phosphorylated p38 mitogen-activated protein kinase in birch pollen allergy.

BACKGROUND: Phosphorylation of p38 MAPK is a crucial step in IgE-receptor signaling in basophils. The relation of p38 MAPK to the well-validated diagnostic cell surface marker CD63 has not been evaluated in a clinical allergy model. METHODS: Expression of CD63 and phosphorylation of p38 MAPK were analyzed flow cytometrically in anti-IgE-gated basophils from 18 birch pollen allergic patients, five grass pollen allergic patients, and five healthy individuals, after 3 and 20 min of stimulation with recombinant major birch pollen allergen (rBet v 1). Additional time points and the influence of p38 MAPK inhibitor SB203580 were studied in birch pollen allergic patients. RESULTS: Phospho-p38 MAPK and CD63 were expressed dose-dependently in birch pollen allergic patient basophils within 1 minute of rBet v 1 stimulation. P38 MAPK phosphorylation was fastest and subsided gradually while CD63 expression remained elevated for at least 20 min. Inhibition of p38 MAPK significantly inhibited CD63 upregulation. With optimal stimulation of the cells (1 µg/mL), sensitivity and specificity for the discrimination between patients and a group of control individuals (grass pollen allergic patients and healthy controls) were 94% and 100% for CD63 at 3 and 20 min and for phospho-p38 MAPK at 3 min. CONCLUSION: Antigen-induced p38 MAPK phosphorylation in human basophils essentially contributes to CD63 upregulation. It is a sensitive and specific intracellular marker for allergy diagnosis and offers new insight into the mechanisms of basophil activation.