Abstract
Purpose :
Meibomian gland dysfunction is the main cause of dry eye disease. To better understand the physiological function of human meibomian glands (MG), the present study compared MG with other free and with hair-associated sebaceous glands (SG) of humans.
Methods :
Eyelids with MG, nostrils, lips and external auditory canals with free SG, and scalp with hair-associated SG of body donors were probed with antibodies against cytokeratins (CK) 1, 8, 10 and 14, stem cell markers keratin 15 and N-cadherin, cell-cell contact markers desmoglein 1 (Dsg1), desmocollin 3 (Dsc3), desmoplakin (Dp), plakoglobin (Pg) and E-cadherin, and the tight junction protein claudin 5. In addition, oil red O staining (ORO) was performed in cryosections. Secretions of MG as well as of SG of nostrils, external auditory canals, and scalp were collected from healthy volunteers, analyzed by LCMS, and the data were processed using Progenesis QI software. A partial least-squares discriminant analysis model was used to compare the secretion composition using EZinfo software. Serial sections of MG, free SG, and hair-associated SG were 3D reconstructed and compared.
Results :
CK1 was expressed differently in hair-associated SG than in MG and other free SG. The expression of CK8, CK10, and CK14 in MG was different from that in hair-associated SG and other free SG. KRT15 was expressed differently in hair-associated SG, whereas N-cadherin was expressed equally in all gland types. The cell-cell contact markers Dsg1, Dp, Dsc3, Pg, and E-cadherin revealed no differences. ORO staining showed that lipids in MG were more highly distributed and had larger lipid droplets than lipids in other free SG. Hair-associated SG had a smaller number of lipid droplets. LCMS revealed that the distribution of meibum levels were far from the sebum levels of the nostrils, external auditory canals, and scalp. The 3D reconstructions of the different glands revealed different morphology of the glands with MG being the largest gland type.
Conclusions :
In humans, MG differ in their morphological and secretory composition and show significant differences from other free and hair-associated SG. The composition of meibum differs significantly from that of sebum from free SGs and from hair-associated SG. Therefore, MG can be considered as a highly specialized type of SG.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.