scRNA-seq reveals the impact of dysfunction on meibomian gland population dynamics
While meibomian gland dysfunction (MGD) is widely recognized as a major cause of evaporative dry eye disease, little is known about normal gland differentiation and lipid synthesis or the mechanism underlying gland atrophy and abnormal lipid secretion. In this study, we used single-cell and spatial transcriptomics to probe changes in cell composition, differentiation, and gene expression associated with two murine models of MGD: age-related gland atrophy in wild-type mice and altered meibum quality in acyl-CoA wax alcohol acyltransferase 2 (Awat2) knockout (KO) mice. We identified the stratified expression of lipogenic genes during meibocyte differentiation, which may control the progressive synthesis of meibum lipids; an age-related decrease in meibocytes; and increased immune cell infiltration. Additionally, we detected unique immune cell populations in the Awat2 KO mouse suggesting the activation of psoriasis-like, inflammatory pathways associated with the synthesis of altered meibum quality causing ductal dilation and hyperplasia of the duct. Together these findings support novel mechanism controlling gland function and dysfunction. Overall design: For the first run of scRNA-seq, meibomian gland WT replicates 1 and 2, we used six WT, 6-month-old, male C57Bl/6 mice, which were pooled into two groups of three. For the second run, we used eight mice, including four 6-month-old, male Awat2 KO mice and four WT, C57Bl/6 litter mates, which were pooled to create the meibomian gland WT 3 and meibomian gland AWAT2 KO samples.