Association of Serum Lipid Level with Meibum Biosynthesis and Meibomian Gland Dysfunction: A Review

Abstract

The primary role of meibomian glands (MGs) is to actively synthesize and secret lipids and proteins spread onto the tear film, and the glandular lipids promote tear stability, prevent evaporation, and reduce friction. Meibomian gland dysfunction (MGD) is the leading cause of dry eye disease and one of the most common ophthalmic problems worldwide. MGs are densely innervated and regulated by hormones and growth factors. However, since the polar and nonpolar lipids are produced through processes in MGs that are not completely understood, a relevant question has been raised: Would the altered systemic lipids metabolism affect the physiology and structure of MGs? This review introduces the recent update regarding the relationships between serum lipid and MGD in clinical and basic research while providing answers to this question. A causal relationship remains to be established; however, serum lipid level or dyslipidemia may be related to MGD directly or indirectly, or both. Further studies are warranted to establish the role of serum lipid level and meibocyte differentiation/maturation and lipid synthesis.

Impact of Dyslipidemia on Tear Film and Meibomian Gland Dysfunction: A Cross-Sectional Study of the Interplay between Serum Lipid Profile and Ocular Surface Health

“…Several studies have investigated the association between dyslipidemia and DED owing to MGD [ 1 , 3 – 6 , 13 , 14 , 16 , 25 , 35 , 37 ]. However, this relationship remains unclear [ 7 , 20 ]. Therefore, this study aims to analyze the relationship between dyslipidemia and DED, as well as its potential influence on tear film and meibomian gland dysfunction.…”

“…Theoretically, the increase in the meibum melting point makes it more viscous at physiologic temperatures leading to meibomian gland obstruction [ 3 , 4 , 13 , 25 , 37 ], which may alter tear film stability and increase its osmolarity, resulting in DED symptoms and signs [ 9 , 37 ]. Second, some studies also suggest that serum lipid levels play a role in meibogenesis [ 7 , 40 ]. Therefore, it is hypothesized that abnormal serum lipid levels may affect the meibogenesis in acinar cells of meibomian glands, as well as the final meibum composition leading to MGD [ 7 ].…”

“…Second, some studies also suggest that serum lipid levels play a role in meibogenesis [ 7 , 40 ]. Therefore, it is hypothesized that abnormal serum lipid levels may affect the meibogenesis in acinar cells of meibomian glands, as well as the final meibum composition leading to MGD [ 7 ]. However, some studies have also reported that elevated TC, LDL, or TG levels were not associated with DED owing to MGD [ 41 – 43 ].…”

“…This condition is a major risk factor for the development of cardiovascular disease, the leading cause of death worldwide [ 3 ]. Recent evidence suggests that dyslipidemia may also have a significant impact on the ocular surface [ 4 – 7 ].…”

“…The lipid layer is composed mainly of meibomian gland secretions, which contain a variety of fatty acids and wax esters [ 8 , 12 ]. Dyslipidemia has been linked to alterations in the meibomian gland secretions, which may lead to a decrease in the quality and quantity of the LLTF [ 4 , 6 , 7 , 13 – 16 ]. This may result in a range of ocular surface disorders, such as dry eye disease (DED), meibomian gland dysfunction (MGD), and blepharitis [ 9 ], which are characterized by symptoms, such as ocular discomfort, foreign body sensation, itching, burning, and blurred vision [ 17 ].…”