Pathobiology of Meibomian Gland at Wakayama 2016

Meibomian gland dysfunction (MGD) is the most frequent cause of evaporative dry eye, yet its underlying pathophysiology is unknown. To gain insight into this pathophysiology, we characterized the time dependent tear film and ocular surface changes occurring in X-linked anhidrotic-hypohidrotic ectodermal dysplasia mice (Tabby), which are absence of meibomian gland. These mice sequentially developed corneal epithelial defects, central corneal stromal edema, neovascularization, and pannus 8 to 16 weeks after birth. Aqueous tear secretion was normal, while tear break-up time and ex vivo tear evaporation times were all shortened. Corneal epithelial microvilli were less numerous, conjunctival goblet cell density was unaffected, and MUC5AC and MUC5B gene expression was increased. Markers of squamous metaplasia (cytokeratin 10 and SPRR1B) were noticed in the corneal epithelium of Tabby mice as early as the 4th week. Taken together, the Tabby mouse is a relevant MGD related dry eye model that may lead to a better understanding how of meibomian glands are related to ocular surface health. It may also help with discovering novel drug options for treating evaporative dry eye. 12 Title: Innervation of the Meibomian Gland in Aging Author: RW Beuerman Singapore Eye Research Institute Duke-NUS Introduction: The specially modified sebaceous glands of the eye-lids have a critical role in supporting the visual function of the cornea. Appropriately the Meibomian Glands, MG, are implicated in dry eye disease, DED. As with other sebaceous glands their function changes with age. Neural sources complement the MGs although their function is not clear. RNA and protein levels for neuropeptide Y (NPY) receptor, vasoactive intestinal peptide (VIP) receptor, substance P (SP) receptor (also known as NK1 receptor) and muscarinic receptor (MR) subtypes m1–m5 in the mouse Meibomian glands. Therapeutic methods for MG secretions are not successful and a goal of this research is to understand how to increase MG function in DED. Methods: Meibomian gland ductal and acinar cells were isolated from frozen sections of eyelids of 4-6week Balb/c mice using laser capture microdissection (LCM). Real-time PCR, immunofluorescent staining and western blot analyses for SP receptor, VIP receptor, NPY receptor and m1–m5 were performed on meibomian gland ductal and acinar cells. Results: Expression of NPY1 receptor, VIP receptor 1, SP receptor and all five MR subtypes was found in all meibomian gland ductal and acinar cells analyzed by immunofluorescent staining. M1 and SP receptor transcripts were undetectable in meibomian gland ductal cells by real-time PCR. Immunofluorescent staining and western blot analysis confirmed the presence of NPY1 receptor, VIP receptor 1, SP receptor and all five MR subtypes in the Meibomian gland. Conclusions: VIP receptor 1, SP receptor, NPY1 receptor and all five MR subtypes may mediate VIP, SP, NP and all five muscarinic acetylcholine subtypes action are involved in regulating synthesis of meibomian gland secretion. These data are considered to be the molecular basis for neuropeptide receptor targeting of dry eye diseases. Using this information the next step is to understand how the neural receptors affect function in aging.