Baicalin reduces the severity of experimental autoimmune encephalomyelitis

Scutellaria baicalensis Georgi is one of the important medicinal herbs widely used for the treatment of various inflammatory diseases in Asia. Baicalin ( BA) is a bioactive anti-inflammatory flavone found abundantly in Scutellaria baicalensis Georgi. To explore the therapeutic potential of BA, we examined the effects of systemic administration of the flavone ( 5 and 10 mg/kg, ip) on relapsing/remitting experimental autoimmune encephalomyelitis ( EAE) induced by proteolipid protein 139-151 in SJL/J mice, an experimental model of multiple sclerosis. The mice treated with PBS or BA at day -1 and for 3 consecutive days were observed daily for clinical signs of disease up to 60 days after immunization. In the PBS-EAE group, neurological scores were: incidence ( 100%), mean day of onset ( 8.0 +/- 0.73), peak clinical score ( 3.0 +/- 0.4), and cumulative disease index ( 141.8 +/- 19.4). In the BA-EAE group ( 5 or 10 mg kg(-1) day(-1), respectively), incidence ( 95 or 90%), mean day of onset ( 9.0 +/- 0.80 or 9.2 +/- 0.75; P = 0.000), peak clinical score ( 2.2 +/- 0.3 or 2.0 +/- 0.3; P = 0.000), and cumulative disease index ( 75.9 +/- 10.1 or 62.9 +/- 8.4; P = 0.000) decreased, accompanied by the histopathological findings ( decrease of dense mononuclear infiltration surrounding vascellum) for the spinal cord. Additionally, the in vitro effects of BA ( 5, 10, and 25 mu M) on mononuclear cells collected from popliteal and inguinal lymph nodes of day-10 EAE mice were evaluated using an MTT reduction assay for cell proliferation, and ELISA to measure IFN-gamma and IL-4 cytokines. Compared with the control group, BA caused an increase in IL-4 (EAE-DMSO: 3.56 +/- 0.42 pg/mL vs EAE-BA (5, 10, and 25 mu M): 6.03 +/- 1.1, 7.83 +/- 0.65, 10.54 +/- 1.13 pg/mL, respectively; P < 0.001); but inhibited IFN-gamma (EAE-DMSO: 485.76 +/- 25.13 pg/mL vs EAE-BA (5, 10, and 25 mu M): 87.08 +/- 9.24, 36.27 +/- 5.44, 19.18 +/- 2.93 pg/mL, respectively; P < 0.001) and the proliferation of mononuclear cells (EAE-DMSO: 0.73 +/- 0.021 vs EAE-BA (5, 10, and 25 mu M): 0.41 +/- 0.015, 0.31 +/- 0.018, 0.21 +/- 0.11, respectively; P < 0.001) in a concentration-dependent manner. The results suggest that BA might be effective in the treatment of multiple sclerosis.