Identification of anti-inflammatory drugs according to their capacity to suppress type-1 and type-2 T cell profiles

Background Down-regulation or modulation of T cell activity by immunosuppressive drugs is an effective treatment in diseases where exaggerated T cell responses play a role. A primary effect of the anti-inflammatory drugs (AIDS) is inhibition of the synthesis of growth factors, such as IL-2, thereby down-regulating T cell proliferation. However, it is still largely unknown to what extent these AIDS are able to down-regulate specifically type-1 or type-2 T cell cytokine production, and whether they can: down-modulate chemokine receptor expression, thereby preventing migration of T cells to the site of inflammation. Objective We investigated the suppressive effect of dermatologically used AID (cyclosporin A (CsA), lactoferrin (LF), 1alpha, 25-dihydroxyvitamin D-3 (VD3), hydrocortisone (HC), di-methylfumarate (DMF), diclofenac (DF)) on both type-1 and type-2 T cells. Since allergic contact dermatitis is a skin disorder in which an exaggerated T cell response of both types of T cell subsets can be observed, we used this disorder as a model to study the capacity of AID to suppress type-1 or type-2 T cell responses. Methods Peripheral blood mononuclear cells of nickel allergic patients were cultured in the presence of allergen and increasing concentrations of AID. Proliferation was determined by measuring H-3 thymidine incorporation; chemokine receptor (CCR10, CCR4, CXCR3) expression was studied by flow cytometric analysis and IFN-gamma or IL-5 cytokine production was measured by ELISA. Results Three major patterns can be distinguished regarding the effect of AID on T cell responses. The first group, including CsA and LF, inhibited non-selectively T cell proliferation, chemokine receptor expression and cytokine production, with CsA as the most potent drug tested. A second group of AID, which included VD3, HC and DMF, suppressed mainly type-1 T cell responses, as revealed by strong interference with IFN-gamma production and CXCR3 expression, and limited effects on either or both IL-5 and CCR4 expression. The third pattern was displayed by DF, which down-regulated IL-5 production and CCR4 expression, whereas IFN-gamma and CXCR3 were unaltered. Conclusions Using a contact allergy model, we have demonstrated that various AIDS show distinct pharmacological profiles in that either type-1 or type-2 or both T cell responses are suppressed. These results should contribute to a more rational selection of AID in treating inflammatory skin diseases mediated by either or both of these T cell subsets.