pSTAT1, pSTAT3, and T-bet expression in peripheral blood mononuclear cells from relapsing-remitting multiple sclerosis patients correlates with disease activity.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system, and it is considered to be a T helper 1 (Th1) cell-mediated autoimmune disease. T-bet has been identified as a key transcription factor for the development of Th1 cells and the induction of interferon (IFN)-gamma production. T-bet is induced during T-cell activation by the IFN-gamma signal transducer and activator of transcription (STAT)-1 signalling pathway. In this study we found an up-regulation of T-bet and pSTAT1 in peripheral blood CD4+ and CD8+ T cells and monocytes from relapsing-remitting MS patients in relapse compared with patients in remission and with healthy subjects. The increased expression of pSTAT1 strongly correlated with T-bet expression in CD4+ and CD8+ cells and monocytes from patients in relapse and was associated with an increased production of IFN-gamma by peripheral blood mononuclear cells (PBMCs). pSTAT3 was also up-regulated in CD4+ and CD8+ cells and monocytes from patients in relapse and was associated with an increased production of interleukin (IL)-10 but not of IL-6. pSTAT1, pSTAT3, and T-bet expression strongly correlated with Gd-DTPA-enhanced lesions on brain and spinal cord magnetic resonance imaging. Our data show for the first time that there is an up-regulation of type 1 immunity-correlated transcription factors such as STAT1 and T-bet in peripheral blood subpopulations of MS patients in the active phase of disease. The evaluation of T-bet and pSTAT1 expression in peripheral blood CD4+, CD8+ T cells and monocytes could be used as a marker of disease activity in relapsing-remitting MS.