Linomide downregulates autoimmunity through induction of TH2 cytokine production by lymphocytes

Linomide is a synthetic immunomodulator that has been shown to protect animals against a wide range of spontaneously developing or induced autoimmune diseases. We have previously reported that Linomide blocks both the clinical and the histopathological manifestations of experimental autoimmune encephalomyelitis (EAE) in various animal models. In this study, in an effort to elucidate the mechanisms by which Linomide suppresses EAE, and autoimmunity in general, we investigated the in vivo effects of this drug on the TH1/TH2 lymphocyte balance, which is important for the induction or inhibition of autoireactivity. Naive SJL/J mice were treated orally for 15 days with Linomide (80 mg/kg/day). Spleen cells were obtained at various time points during the treatment period and were stimulated in vitro with concanavalin A. Interleukins IL-4, IL-10 and IL-12, transforming growth factor-beta (TGFbeta) and interferon-gamma (IFNgamma) cytokine production was evaluated both by means of detection of the cytokines in the medium (by ELISA technique) and by detection of the cytokine mRNA production, using a semiquantitative reverse transcriptase polymerase chain reaction method. A significant upregulation of IL-4, IL-10 and TGFbeta was observed following treatment with Linomide, which peaked at day 10 (IL-10) or day 15 (IL-4). On the other hand, IL-12 and IFNgamma production were either unchanged or decreased. It seems therefore that Linomide induces in vivo a shift towards TH2 lymphocytes which may be one of the mechanisms of downregulation of the autoimmune reactivity in EAE. Our observations indicate that downregulation of TH1 cytokines (especially IL-12) and enhancement of TH2 cytokine production may play an important role in the control of T-cell-mediated autoimmunity. These data may contribute to the design of new immunomodulating treatments for a group of autoimmune diseases.