Ethanol extract of Glycyrrhizae Radix modulates the responses of antigen-specific splenocytes in experimental autoimmune encephalomyelitis

• Published in: Phytomedicine (Stuttgart) 2019-02, Vol.54, p.56-65
• Main Authors: Yang, Eun-Ju, Song, Im-Sook, Song, Kyung-Sik
• Format: Article
• Language: English
• Subjects: Animals; Cells, Cultured; Cytokines - metabolism; Encephalomyelitis, Autoimmune, Experimental - drug therapy; Encephalomyelitis, Autoimmune, Experimental - immunology; Encephalomyelitis, Autoimmune, Experimental - metabolism; Ethanol - chemistry; Female; Glycyrrhiza - chemistry; Glycyrrhizae Radix; Immunomodulation; Interferon-gamma - metabolism; Interferon-γ; Interleukin-17; Mice, Inbred C57BL; Microglia; Microglia - drug effects; Multiple sclerosis; Myelin-Oligodendrocyte Glycoprotein - immunology; Nitric Oxide - metabolism; Peptide Fragments - immunology; Plant Extracts - chemistry; Plant Extracts - pharmacology; Spleen - cytology; Spleen - drug effects; Spleen - immunology; Splenocytes; Th1 Cells - drug effects; Th1 Cells - immunology
• ISSN: 0944-7113; 1618-095X
• DOI: 10.1016/j.phymed.2018.09.189

Multiple sclerosis (MS) is an autoimmune disorder resulting in paralysis, and the responses of reactive T cells against self-antigens are hallmarks. Glycyrrhizae Radix (GR) has been used for detoxification and reducing inflammation. However, very few reports have described the effects of GR on MS. The immunomodulatory effects of GR extract on autoimmune responses were evaluated through in vitro, ex vivo, and in vivo assays using primary mouse splenocytes (SPLC), mouse microglia BV2 cell line, and a mouse model of experimental autoimmune encephalomyelitis (EAE). Ethanol extract of GR was used in vitro with primary SPLC in the condition of anti-CD3/CD28 stimulation and interferon (IFN)-γ-producing CD4+ (TH1)/CD8+ (TC1) polarization as well as IFN-γ-stimulated BV2 cells. For EAE induction, female C57BL/6 mice were immunized with 200 μg of myelin oligodendrocyte glycoprotein (MOG)35–55 without pertussis toxin. EAE SPLC (ex vivo) and EAE mice (in vivo) were treated with GR extract to evaluate the changes in antigen-specific responses. SPLC media containing antigen-specific responses were used to stimulate BV2 cells. GR extract effectively modulated the responses of reactive splenic T cells through the reduction in IFN-γ+ T cell populations, the expressions of cell adhesion molecules (CAMs), and secretions of cytokines containing IFN-γ and a chemokine IFN-γ-induced protein 10 (IP-10) in vitro. In addition, GR extract significantly decreased nitric oxide production and secretion of tumor necrosis factor (TNF)-α and IP-10 in IFN-γ-stimulated BV2 cells. The antigen-specific TH1 and TC1 populations were decreased following administration of 100 mg/kg of GR extract, whereas CD8+IL-17A+ (TC17) population was increased on day 36 after EAE induction. Moreover, IFN-γ, which showed the highest secretion among examined cytokines, and IP-10 decreased on day 36. SPLC media derived from 100 mg/kg GR extract-administered EAE mice revealed the ameliorative effects on BV2 cell stimulation. This is the first report on the immunomodulatory effects of GR extract on antigen-specific SPLC responses in EAE. These results could be helpful for the discovery of drug candidates for MS by focusing on IFN-γ-related autoimmune responses. [Display omitted]