Abstract
Purpose :
Oral supplementation with omega 3 (ω-3) and/or 6 (ω-6) fatty acids (FAs) has been reported to alleviate the signs and symptoms of dry eye disease (DED), and to improve the expressibility and quality of meibum, in patients with meibomian gland dysfunction (MGD). We hypothesized that these FA effects may reflect a direct FA action on human meibomian gland epithelial cells (HMGECs). Our purpose was to test this hypothesis.
Methods :
Immortalized (I) HMGECs were cultured with ω-3 (10 µM), ω-6 (10 µM) or both FAs together (5µM each) for up to 7 days in the presence or absence of serum. Cells were evaluated for neutral lipid (LipidTox) staining, as well as the appearance of lysosomes (LysoTracker) and lysosomal markers, Lamp-1 and LC3 (Western blot). The lipid composition of cellular lysates was analyzed by high performance thin-layer chromatography.
Results :
Our research shows that ω-3 and ω-6 stimulate the accumulation of small neutral lipid-containing vesicles, but not lysosomes, in IHMGECs. This vesicular effect was associated with a 2.4- to 3.7-fold increase in the cellular content of triglycerides following ω-3 and ω-6 treatment, respectively. The combination of both FAs together also enhanced triglyceride levels. Of particular interest, culture of IHMGECs with ω-3 and azithromycin (AZM; 10 µg/ml), a known inducer of IHMGEC differentiation, led to a significantly greater amount of total neutral lipids, relative to that found with AZM alone. Cellular exposure to the FAs did not alter the expression of free or esterified cholesterol, or phospholipids. Further, these FAs, alone or together, reduced the proliferation of IHMGECs in serum-free, but not serum-containing, media.
Conclusions :
Our findings support our hypothesis and demonstrate that ω-3 and ω-6 can act directly on IHMGECs to influence the quality and quantity of intracellular lipids. It is possible that these cellular effects may contribute to the beneficial actions of these FAs on the signs, symptoms and meibum quality of patients with MGD and DED.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.