Preventive and therapeutic effects of compound wild chrysanthemum eye pad on blue light-induced alteration of meibomian gland function in mice and its mechanism

To investigate the preventive and therapeutic effects of compound wild chrysanthemum eye pad on blue light-induced alteration of meibomian gland function in mice and its mechanism.

Sixty-four 15-week-old male C57BL/6J mice were divided into two groups of 32 mice each according to random numbers for the prevention test and the treatment test.The respective 32 mice in the prevention and treatment experiments were randomly divided into normal group, blue light group, solvent group and eye pad group according to random numbers, with eight mice in each group, respectively.In the prevention experiments, mice in each group were exposed to blue light at a wavelength of 460 nm and a light intensity of 2 000 lx for 6 hours per day for 15 consecutive days to establish a mouse model of meibomian gland function changes except for the normal group.The solvent group and the eye pad group were treated with the corresponding eye pad before and after the blue light exposure for 25 minutes daily for the 15 consecutive days.The blue light group was treated with blue light exposure only for 15 days, and the mice were photographed at the edge of the meibomian gland on day 15 to observe the function of the meibomian gland except for the normal group.In the treatment test, all groups of mice except the normal group were induced the altered function of the mouse meibomian gland by the above method.The solvent and eye pad groups were treated with corresponding eye pads for 25 minutes in the morning and afternoon of each day for 15 consecutive days after blue light exposure.The blue light group was kept in a standard environment for 15 days and the changes in meibomian gland function of mice were detected by meibomian gland photographs on day 15.Photography of the eyelid margin in vitro, oil red O staining, and hematoxylin-eosin staining were performed to observe the histologic changes in the meibomian glands of mice after the preventive and experimental treatment.The relative expression of interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) mRNA in mouse meibomian gland tissues was detected by real-time fluorescence quantitative PCR.The expression of nuclear factor-κB (NF-κB) and phosphorylation of NF-κB (p-NF-κB) proteins in mice meibomian gland tissues was detected by Western blot to assess the degree of amelioration of blue light-induced inflammation in mouse meibomian glands by the compound wild chrysanthemum eye pad.This study was conducted in accordance with the Statement of the Association for Research in Vision and Ophthalmology on the Use of Animals in Ophthalmology and Vision Research, and was approved by the Animal Ethics Committee of Xiamen University (No.XMULAC20220258).

Compared with the normal group, a gradually increased number of blocked meibomian gland openings, and a gradually decreased remaining area of lower meibomian gland, were observed in the mice after 15 days of blue light group, and all the differences were statistically different (all at P<0.05). In the prevention test, the number of obstructed opening in the eye pad group was 1.833±0.753, which was significantly less than 3.667±1.033 in the solvent group (P<0.05). The relative remaining area of the lower lid meibomian gland in the eye pad group was 0.718±0.091, which was significantly greater than 0.624±0.130 in the solvent group (P<0.05). Hematoxylin-eosin staining showed inflammatory cell infiltration in mouse meibomian gland in the blue light and solvent groups.There was no inflammatory cell infiltration in eye pad group, and the morphology of the acini was similar to that of the normal group.Oil red O staining showed that there was no significant lipid deposition in the groups.The relative expressions of IL-1β, IL-6, TNF-α, and IFN-γ mRNA were significantly lower, and the relative expressions of NF-κB and p-NF-κB proteins were significantly lower in the eye pad group than in the solvent group, showing statistically significant differences (all at P<0.05). In the treatment test, the number of obstructed openings in the eye pad group and solvent group was 4.333±1.211 and 4.833±1.722, respectively, and the relative remaining area of the lower meibomian gland was 0.572±0.151 and 0.588±0.154, respectively, showing no statistically significant differences (both at P>0.05). Hematoxylin-eosin staining showed inflammatory cell infiltration in mouse meibomian glands in the blue light and solvent groups, with a similar morphology of acini as in the normal group.There was no inflammatory cell infiltration in eye pad group.Oil red O staining showed that there was no significant lipid deposition in the groups.The relative expressions of IL-1β, IL-6, and IFN-γ mRNA were significantly lower and the relative expressions of NF-κB and p-NF-κB proteins were significantly lower in the eye pad group than in the solvent group (all at P<0.05).

Compound wild chrysanthemum eye pad may have preventive and therapeutic effects on blue light-induced changes in meibomian gland function by reducing the inflammatory response of meibomian gland tissue through the inhibition of the NF-κB signaling pathway.