Preliminary Study On Therapeutic Effect Of VitB6 Eye Drops On PM_2.5-Induced Dry Eye In Mice

Objective:To investigate the therapeutic effect of vitamin B6?VitB6?eye drops on the mouse dry eye model induced by particulate matter(PM_2.5).Methods:Totally sixty male Balb/c mice aged 6⁸ weeks were selected and 10 were randomly selected as the normal control group?NC?.The other 50 were induced to dry eyes in the standard environment using 5 mg/mL PM_2.5 eye drops.?right eye,4times/day,14 consecutive days?.Modeling for 14 days,Eyes with similar clinical indicators of dry eye were selected according to parameters including Schirmer I test?SIT?,tear break-up time?TBUT?,corneal fluorescein staining?FL?,rose bengal staining?RB?,Lissamine Green staining?LG?and inflammatory index,and randomly divided into A,B,C,D 4 groups:dry-eye control group,PBS eye drop group,0.02%VitB6 group and 0.05%VitB6 group.4 times a day for 14 consecutive days.Tear volume,TBUT,FL,RB,LG,level of corneal inflammation and corneal confocal microscopy were sequentially performed before and on the 7th,14th day of the treatment.On the 14th day of therapy,the eyeballs,eyelid and corneal tissues of the mice were obtained,and hematoxylin-eosin staining?HE?,periodic acid-Schiff staining?PAS?,TUNEL staining,immunofluorescence labeling and Western Blot were assessed.Results:There were no statistical differences among the four groups before treatment.At the other time points,in group C and D,the amount of lacrimal secretion increased,the inflammation index decreased,and the FL and LG stains were significantly decreased compared with group A and B?P<0.05?.but there was no significant difference between group C and group D?P>0.05?.On the 7th day of treatment,compared with group A and group B,the RB staining score of group C decreased,but the difference was not statistically significant?P>0.05?,while group D had significant difference compared with group A and B?P<0.05?.On the 14th day of treatment,compared with the A and B groups,the TBUT was significantly prolonged,and the score of RB was significantly lower in the C and D groups?P<0.05?.Confocal microscopy showed that,comparing with group A and group B,the corneal epithelial nerve density and number of branches increased significantly,and the curvature score decreased in group C and D.Corneal morphology showed that the feature of thicker corneal epithelial layer in group A and group B,and integrity and smoothness in group C and D.PAS staining showed that the number of goblet cells in the fornix conjunctival of group C and D increased than that in the group A and B,but the difference was not statistically significant?P>0.05?.Apoptosis experiments showed that the apoptosis of corneal epithelial and basal epithelial cells in group A and B were significantly higher than that in group C and D?P<0.05?.Immunofluo-rescence staining showed that the expression of K10 in the C and D groups was down-regulated.The results of Western Blot showed that the expression levels of p-NF-?B p65 in the C and D groups were significantly lower than those of group A and B?P<0.05?.Conclusions:Topical application of 0.05% VitB6 eye drops play a certain role on PM_2.5-induced dry eye in a mouse model,and the possible mechanism may relate to factors that VitB6 can relieve ocular surface inflammation,repair corneal nerve injury,inhibit apoptosis of corneal cells and reduce corneal squamous metaplasia induced by PM_2.5.