Purpose: A novel meibomian gland dysfunction (MGD) model was developed to facilitate understanding of the pathophysiology of MGD and to evaluate treatment with azithromycin ophthalmic solution (azithromycin). MGD was induced in HR-1 hairless mice by feeding them a special diet with limited lipid content (HR-AD).
Methods: Male HR-1 hairless mice were fed an HR-AD diet for 16 weeks. Development of MGD was assessed by histopathology at 4-week intervals. The lid margin was observed by slit-lamp examination. After cessation of the HR-AD diet, the mice were fed a normal diet to restore normal eye conditions. Expression of cytokeratin 6 was determined by immunostaining. We evaluated the effects of topically applied azithromycin on the plugged orifice in this model.
Results: After mice were fed the HR-AD diet, histopathology analysis showed hyperkeratinization of the ductal epithelium in the meibomian gland. Ductal hyperkeratinization resulted in the loss of acini, followed by atrophy of the gland. Slit-lamp examination revealed a markedly plugged orifice, telangiectasia, and a toothpaste-like meibum compared with that of a normal eyelid. Cessation of feeding with HR-AD ameliorated both the MGD signs and the expression of cytokeratin 6, restoring the tissue to a histologically normal state. Azithromycin treatment significantly decreased the number of plugged orifices and ameliorated atrophy, as revealed by histopathologic analysis.
Conclusions: We developed a novel model that mimics human MGD signs in HR-1 hairless mice fed an HR-AD diet. Azithromycin treatment led to therapeutic improvement in this model. This MGD model could be useful for the evaluation of drug candidates for MGD.