Effects Of Cinnamaldehyde On Inflammatory Response In Experimental Autoimmune Encephalomyelitis Mice

Objective: We design and implement the experiment to find the effect of cinnamaldehyde on inflammatory response in experimental autoimmune encephalomyelitis(EAE)mice.The purpose of this experiment is to investigate the effect of cinnamaldehyde on EAE microglia and inflammatory factors TNF-α,IL-1β,IL-6,and provide meaningful basis experimental results for the treatment of the multiple sclerosis.Methods: There are 60 C57BL/6 mice,which are weight eighteen to twenty-two and eight to ten weeks.We randomly divided into control group,EAE group,cinnamaldehyde group(50 mg/kg)and dexamethasone group(0.07 mg/kg).We immune C57BL/6 mice by MOG35-55 as antigen to establish the model of EAE,we dilution the antigen MOG35-55 with physiological saline to 10 mg/ml in a liquid state,and add completed freund’s adjuvant(which contains mycobacterium tuberculosis H37 Ra in a final concentration of 4 mg/ml)into them,whose volume are 1:1,then mix them uniformly.After emulsification we subcutaneous injection a mice on either side of the spine in four points by 0.1ml.On the immune day,we subcutaneous injection 0.5ml PTX at the 0h and 48 h.Since the model is established,we give cinnamaldehyde 50 mg/kg to cinnamaldehyde group by intraperitoneal injection of alternate days;give dexamethasone sodium phosphate injection 0.07 mg/kg to dexamethasone group by intraperitoneal injection of alternate days;control group and EAE group are given the same amount of 0.9% saline dimethyl sulfoxide solution alternate days celiac injection.We record the immune day as 0 day,and take 20 days(the peak)to compare the morbidity and the incidence of nerve function score,and put the mice to death,to return the specimen,with HE staining was used to observe the infiltration of inflammatory cells in spinal cord.The quantity of MG in brain tissue was observed by immunofluorescence.The expression of TNF-α,IL-1β and IL-6 in peripheral blood was determined by ELISA.Transcription of TNF-α,IL-1β and IL-6 m RNA in brain tissue was measured by PCR.Results:1 Observe the clinical incidence and onset time of mice : after immunization,except the control group,mice in other groups showed decreased appetite,indolence,dull fur,and even ulceration.The morbidity in EAE group(100%)was observably higher than that in cinnamaldehyde group(46.7%)and dexamethasone group(40%),with statistically significant difference(P<0.01).The onset time of mice in the EAE group(12.87±0.99 days)was visibly earlier than that in the cinnamaldehyde group(16.38±1.77 days)and the dexamethasone group(17.29±1.60 days),with statistically significant differences(P<0.01).2 Weight change of mice in each group: at the peak of the disease,the mean weight of mice in control group,EAE group,cinnamaldehyde group and dexamethasone group was 21.43±1.07 g,17.53±1.00 g,20.11±1.45 g and 21.45±1.05 g.The mean weight of mice in control group,cinnamaldehyde group and dexamethasone group was significantly higher than that in EAE group.The difference was statistically significant(P<0.01).3 Behavioral observation: at the peak of the disease,the mean neurological scores in control group,EAE group,cinnamaldehyde group and dexamethasone group were 0,2.67±0.56,1.44±0.56 and 1.36±0.69,respectively.The neurological scores in cinnamaldehyde group and dexamethasone group were significantly lower than those in EAE group.The difference was statistically significant(P<0.01).4 The infiltration degree of inflammatory cell in the spinal cord: there was no obvious infiltration of inflammatory cells in the spinal cord of control group,and the myelin sheath was well preserved and orderly.In EAE group,the inflammatory cell infiltration and demyelination were observed in the white matter of spinal cord.Compared with EAE group,the inflammatory lesion and demyelination area of cinnamaldehyde group and dexamethasone group were decreased.5 Observation of microglia in brain tissues of each group of mice: most microglia of control mice were in resting state;the activated microglia in EAE group were significantly more than those in cinnamaldehyde group and dexamethasone group.6 Expression of TNF-α,IL-1β and IL-6 in peripheral blood: the average levels of TNF-α、IL-1β and IL-6 in control group were 33.80±19.25pg/ml,21.03±9.47pg/ml and 13.02±6.28pg/ml;in EAE group were 49.71±5.36pg/ml,31.66±11.40pg/ml and 63.54±26.06pg/ml;in cinnamaldehyde group were 29.53±8.20pg/ml,21.97±4.97pg/ml and 41.83±20.42pg/ml;in dexamethasone group were 19.97±19.09pg/ml,16.54±3.69pg/ml and 37.37±20.88pg/ml.The TNF-α,IL-1β and IL-6 in peripheral blood of the control group,the cinnamaldehyde group and the dexamethasone group were lower than those in the EAE group.The difference was statistically significant(P<0.05).7 Transcription of TNF-α,IL-1β and IL-6 m RNA in brain tissue: the average contents of TNF-α,IL-1β and IL-6 m RNA in control group were 1.23±0.90,0.24±0.02 and 0.86±0.20;in EAE group were 27.42±16.65,6.96±0.95 and 1.88±0.61;in cinnamaldehyde group were 2.61±1.38,1.54±0.44 and 0.59±0.18;in the dexamethasone group were 0.96±0.17,1.11±0.10 and 0.88±0.22.The contents of TNF-α、IL-1β and IL-6 m RNA in the control group,the cinnamaldehyde group and dexamethasone group were lower than those in the EAE group.The difference was statistically significant(P<0.05).Conclusions:1 Cinnamaldehyde can reduce the incidence of EAE mice,delay the onset of disease,and cut down the degree of neurological impairment.2 Cinnamaldehyde was able to reduce inflammatory cell infiltration in the spinal cord of EAE mice and inhibit the activation of microglial cells in the central nervous system.3 Cinnamaldehyde reduced TNF-α,IL-1β and IL-6 levels in the peripheral and central nervous systems of EAE mice.