Abstract
Purpose :
Meibomian gland dysfunction (MGD) accounts for 85% of the cases of dry eye disease (DED), affecting approximately 21 million individuals in the United States. Age-related MGD (ARMGD) occurs with aging where Meibomian glands (MGs) undergo atrophy and drop-out. The etiology of ARMGD remains unknown mainly due to the difficulty in studying its pathogenesis in human subjects. The nonhuman primate (NHP) model is closely related to humans and develops many diseases comparable to humans. This study compares the morphology of the MGs in young and aging NHPs with that of humans as a potential model of ARMGD.
Methods :
Human and NHP eyelids of different ages were obtained and whole mount images taken under the Zeiss Stereomicroscope Discovery.V12. The tarsal plates were isolated and processed for cryosectioning and subjected to hematoxylin and eosin and Oil-red-O staining to assess the morphology of healthy and atrophic glands. Sections were then processed for immunohistochemistry to stain for hyaluronan, PPARγ, K14, Ki67 and LRIG1.
Results :
In NHPs, ~ 29-39 MGs are present in the upper eyelids, and ~ 25-36 MGs in the lower eyelids, compared to ~ 30-40 MGs in the upper eyelids and 20-30 MGs in the lower eyelids in humans. Morphologically, MGs of NHPs are very similar to humans though the ~ 17-23 central MGs of the upper eyelid are longer than the remaining MGs. These longer MGs are anatomically distinct, with the two thirds of the length of the glands furthest from the eyelid margin appearing thinner than the remaining MGs. Some NHPs present with MG tortuosity, and as they age, NHPs present acinar atrophy and regression that begins in the acini furthest from the eyelid margin with eventual drop-out as seen in human subjects,.
Conclusions :
NHPs present with similar MG morphology as humans. With aging, NHPs present with MG atrophy and drop-out similar to what is observed in humans. To the best of our knowledge, this is the first study to show that NHPs present MG atrophy and dropout as they age, and therefore could serve as a valuable model to study ARMGD.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.