Spatial transcriptome analysis of the human eyelid depicts meibomian gland cell differentiation: A pilot study

Meibomian glands (MGs) are an integral component of the ocular defense system, as their secretion product, meibum, is essential for protecting the eye surface. To characterize the transcriptional program underlying meibum production, we employed spatial transcriptomics (ST) analysis of the human eyelid from a sample from a 60-year-old male. We resolved 18 distinct eyelid clusters, representing structures such as the conjunctiva, epidermis, hair-associated sebaceous glands, and MGs. Focusing on the MG, we distinguished basal (MEI-B cluster) and differentiating (MEI-DIFF cluster) meibocytes, as well as a third, duct-related cluster (MEI-DUCT). Self-organizing maps (SOM) portrayal of ST images and pseudotime analysis confirmed progress from MEI-B to MEI-DIFF and further to MEI-DUCT, as the latter turned out to include terminally differentiated meibocytes. Accordingly, gene set enrichment analysis associated early/intermediate meibocyte maturation with energy and lipid metabolism, and later stages with barrier functions. We also identified significant differences between the MG and sebaceous gland transcriptomes. The MG-specific signature included transcripts such as AQP9, MMP3, and PITX1, and selective expression of PITX1 in the MG compared to the sebaceous gland was confirmed by immunohistochemistry on the same sample and samples from three other elderly adults. We deliver the first spatial portrait of the human MG transcriptional landscape. Besides enhancing our understanding of MG physiology, our study identifies novel targets for regulating MG homeostasis in health and disease.