The Effect of Aqueous Extract of Tarragon on Clinical Symptoms and T Cell Differentiation in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is one of the autoimmune diseases that affects the central nervous system (CNS) and causes myelin loss and axonal damage. Recent studies have shown the important role of autoreactive T cells in the pathogenesis of MS. One of the plants in the Astersa family, which has therapeutic benefits is Artemisia dracunculus L. or Tarragon. In this study, the role of aqueous extract of Tarragon in suppressing Th1 and Th17 cell differentiation and ameliorating experimental autoimmune encephalomyelitis (EAE) was investigated. EAE was induced in C57BL/6 female mice by Hook kit MOG35-55/CFA Emulsion PTX and one group was treated with Tarragon at a dose of 500 mg/kg. Mice were euthanized on day 33 post-immunization, spleens were removed for assessing Th1, Th17 and Treg cells by flow cytometry. We provided evidence that Tarragon (500 mg/kg) significantly ameliorated clinical scores of EAE. We did not observe significant alterations in T cell differentiation to Th1, Th17 or Treg in the spleen of mice during EAE. This is the first experimental evidence showing that administration of aqueous extract of Tarragon reduces the severity of EAE, but the protective effect of Tarragon is independent of alteration in T cells in the spleen. These results suggest other mechanisms for the effectiveness of this extract in improving the EAE process.