Candidate Molecular Compounds as Potential Indicators for Meibomian Gland Dysfunction

Abstract

Meibomian gland dysfunction (MGD) is the leading cause of dry eye disease throughout the world. Studies have shown that several molecules in meibum, including but not limited to interleukins, amino acids, cadherins, eicosanoids, carbohydrates, and proteins, are altered in meibomian gland dysfunction compared with healthy normal controls. Some of these molecules such as antileukoproteinase, phospholipase A2, and lactoperoxidase also show differences in concentrations in tears between meibomian gland dysfunction and dry eye disease, further boosting hopes as candidate biomarkers. MGD is a complex condition, making it difficult to distinguish patients using single biomarkers. Therefore, multiple biomarkers forming a multiplex panel may be required. This review aims to describe molecules comprising lipids, proteins, and carbohydrates with the potential of serving various capacities as monitoring, predictive, diagnostic, and risk biomarkers for meibomian gland dysfunction.

Meibomian Gland Shortening Is Associated With Altered Meibum Composition

“…Previous studies on meibum proteomics revealed that meibomian glands secrete a number of proteins into the tear film and more than 90 proteins have been identified in human meibum involving keratins (K1, 5, 6, 7, 9, 10, 13, and 16), surfactant proteins (SP-B and SP-C), lipocalins, lactoferrin, phospholipid transfer proteins, lipophillins, cytochrome c, farnesoid X laminin α-3 chain, lysozyme c, and proteoglycans. 60 – 62 It is intriguing here that, overall, the lipids were reduced in short glands, but the protein concentration was higher. How proteins interact with lipids and their association with gland morphology needs to be explored further.…”

Human tear film protein sampling using soft contact lenses

“…At the same time, unique protein species in SS sampling may indicate biochemical changes associated with reflex tearing. While contaminants such as keratins can be introduced during sample prep, they are also an important component of meibum [ 35 ] and are expected to be present in tears, given the proximity of host ocular adnexal skin. Thus, keratins should be considered a natural component of tears.…”