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The purpose of this study was to characterize the age-related changes of the mouse meibomian gland. Eyelids from adult C57Bl/6 mice at 2, 6, 12 and 24 months of age were stained with specific antibodies against peroxisome proliferator activated receptor gamma (PPARγ) to identify differentiating meibocytes, Oil Red O(ORO) to identify lipid, Ki67 nuclear antigen to identify cycling cells, B-lymphocyte-induced maturation protein-1 (Blimp1) to identify potential stem cells and CD45 to identify immune cells. Meibomian glands from younger mice (2 and 6 months) showed cytoplasmic and perinuclear staining with anti-PPARγ antibodies with abundant ORO staining of small, intracellular lipid droplets. Meibomian glands from older mice (12 and 24 months) showed only nuclear PPARγ localization with less ORO staining and significantly reduced acinar tissue (p<0.04). Acini of older mice also showed significantly reduced (p<0.004) numbers of Ki67 stained nuclei. While Blimp1 appeared to diffusely stain the superficial ductal epithelium, isolated cells were occasionally stained within the meibomian glandduct and acini of older mice that also stained with CD45 antibodies, suggesting the presence of infiltrating plasmacytoid cells. These findings suggest that there is altered PPARγ receptor signaling in older mice that may underlie changes in cell cycle entry/proliferation, lipid synthesis and gland atrophy during aging. These results are consistent with the hypothesis that mouse meibomian glands undergo age-related changes similar to those identified in humans and may be used as a model for age-related meibomian gland dysfunction.

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More than two-fold RT differences were found for the higher viscosity, more muco-adhesive formulations compared to saline. However, other formulations provided RTs close to saline, suggesting that RT is influenced by factors other than simple viscosity. Future studies should examine the interplay of spreading characteristics, pseudoplasticity and muco-adhesion relative to RT to determine the individual and cumulative effects on formulation retention.