Novel therapeutic approach by nicotine in experimental model of multiple sclerosis

Abstract

Background: Multiple sclerosis is an autoimmune, neurodegenerative disease of the central nervous system. The cause of multiple sclerosis is still unknown, and there is no cure for multiple sclerosis. Experimental autoimmune encephalomyelitis is considered as an animal model for multiple sclerosis. The therapeutic role of nicotine has been proven to be effective in both Alzheimer's and Parkinson's disease, thus we examined, for the first time, the role of nicotine in the experimental autoimmune encephalomyelitis model.

Methods: Experimental autoimmune encephalomyelitis induction was performed according to Guang-Xian Zhang et al. Treatment with nicotine was started on Day 7 post-immunization. Prevention with nicotine was started on Day 7 pre-immunization. Also for in-vitro analysis, we used U-87 MG cell line to evaluate the inhibitory effect of nicotine in cell proliferation, pro-inflammatory cytokines (TNF-alpha, IL-lbeta, IL-6) and MMP-2 activity by MTT, ELISA, and zymoanalysis methods, respectively. Moreover, the brains of mice were removed for histological analysis.

Results: Our findings showed that treatment with nicotine caused a significant reduction in the severity and onset of the experimental autoimmune encephalomyelitis. Histological analysis indicated that there was very mild and mild plaque in the brain sections of nicotine prevention and treatment groups, respectively.

Conclusion: Our data indicate that nicotine can significantly improve the clinical score and attenuate the demyelinating pathology typically found in experimental autoimmune encephalomyelitis, indicating that nicotine has protective effects in experimental model of multiple sclerosis.

Keywords: MMP-2; Multiple sclerosis; nicotine.

FIGURE 1

Mean clinical scores of EAE induced by MOG_35-55 in control, prevention, and treatment groups with nicotine. All mice were immunized with MOG_35-55 emulsified in CFA and screened every day for the assessment of clinical signs of EAE. Nicotine can decrease the severity and onset of EAE (P<0.05).

FIGURE 2

The onset of clinical signs in EAE. There is a significant difference between control and prevention groups and a significant difference between prevention and treatment groups (P<0.05).

FIGURE 3

Status of neuroinflammatory reactions in different groups. A, B, and C as normal group (A=brain, B and C=cerebellum); D, E, F, G as patient group (D=spongious in cerebellum, E=hypercellularity and cell infiltration in cerebellum, F=perivascular cuffing and cell margination in the brain, G=spinal cord); H, I, J, K as prevention group (H=cerebellum hypercellularity, I=spongiou and cell margination in spinal cord, J= cerebellum, K=brain); L, M, N as treatment group (L=brain hypercellularity, M=mild cell margination in cerebellum, N=spongious in spinal cord)

FIGURE 4

Status of demyelination in different groups. A, B, C as normal group (spinal cord, brain, cerebellum, respectively); D, E as patient group (D=brain, E=spinal cord); F, G as prevention group (F=cerebellum, G=spinal cord); H, I as treatment group (H=spinal cord, I=cerebellum)

FIGURE 5

Assessment of MMP-2 activity by gelatin zymography in human glioblastoma (U87MG) cells. High dose of nicotine (500 and 1,000μgr/well) could suppress cell proliferation while low concentration of nicotine (1, 5, 10, 50, 100μgr/well) had proliferative effect on these cells. Untreated=0μg, treated=1-1,000μg.