Effects Of Glucosamine On Allergic Conjunctivitis In A Murine Model Induced By Ovalbumin

ObjectiveTo evaluate the therapeutic effect of glucosamine on experimental allergic conjunctivitis on mice.MethodsForty female Balb/c mice（40 eyes）aged 6-8 weeks were randomly divided into 5 groups:blank control group,allergic conjunctivitis group,glucosamine systemic treatment group,glucosamine topical treatment group,dexamethasone treatment group,8 in each group.From the start of the experiment,On the 0th and the 7th day,100μg of ovalbumin and 200μl of aluminum hydroxide adjuvant were completely mixed at a volume ratio of 1:2,and the mixture was intraperitoneally injected;On the 15th to 18th day,mice were activated by OVA drops（250μg）onto the counjunctival sac.The blank control group was replaced by equal amount of sterile saline during the sensitization and challenge phases.On the 15th to 18th day after the modeling,we started drug intervention after activation with eye drops for 30 min.The glucosamine systemic treatment group was given 0.2 ml of glucosamine(50 mg·ml^-1)Intraperitoneal injection,once a day,glucosamine topical treatment group was given 50μl glucosamine(50mg·ml^-1)solution,4 times a day,the dexamethasone treatment group was given50μl dexamethasone eye drops（5ml:1.25 mg）for 4 times a day.The symptoms of the mouse eyes were observed within 30 min after the 19th day of challenge.The levels of IgE in serum and the expression levels of inflammatory factors IL-4,IL-5 and IFN-γin serum culture supernatant were detected by ELISA.HE staining was used to detect the infiltration of eosinophils in the conjunctiva.Results1.After the last challenge,the mice in the blank control group had no obvious allergic symptoms.The allergic conjunctivitis group developed severe allergic symptoms.Mild allergic symptoms were observed in the glucosamine systemic treatment group,the glucosamine topical treatment group,and the dexamethasone group.The clinical symptom scores of glucosamine systemic treatment group and topical treatment group were lower than those of the model group（P<0.01）.The difference in the dexamethasone treatment group and the glucosamine systemic treatment group had no statistical significance（P>0.05）;There was no difference between the glucosamine systemic treatment group and the topical treatment group（P>0.05）.2.The eosinophil counts of conjunctiva in each group were higher than those in the control group and lower than that in the allergic conjunctivitis group,the difference was statistically significant（P<0.01）.There was no significant difference between the dexamethasone Treatment group,the glucosamine systemic treatment group and the glucosamine topical treatment group（all P>0.05）.3.The serum IgE content of allergic conjunctivitis group was higher than that in other groups.The serum IgE content of glucosamine topical treatment group was lower than that in the dexamethasone treatment group and higher than that in glucosamine systemic treatment group.The differences were statistically significant（all P<0.05）.4.The expression levels of IL-4 and IL-5 in the spleen cell culture supernatant of each group were higher than those in the blank control group（all P<0.01）;the other groups was lower compared with the allergic conjunctivitis model group（all P<0.01）;the glucosamine systemic treatment group was lower than the glucosamine topical treatment group（all P<0.05）.The IFN-γcontent of each group was significantly lower than that in the blank control group（all P<0.01）.There was no significant difference between the other groups（P>0.05）.Conclusions1.Both systemic and topical administration of glucosamine can relieve the symptoms of allergic conjunctivitis in mice,reduce eosinophil accumulation,reduce serum IgE content.The therapeutic effect was no different from dexamethasone.2.Systemic treatment is superior to topical treatment in reducing serum IgE content.3.The mechanism of action of glucosamine in allergic conjunctivitis may be related to the reverse Th1/Th2 imbalance by reducing the expression of Th2type cytokines.