Obese Mice with Dyslipidemia Exhibit Meibomian Gland Hypertrophy and Alterations in Meibum Composition and Aqueous Tear Production.

BACKGROUND: Dyslipidemia may be linked to meibomian gland dysfunction (MGD) and altered meibum lipid composition. The purpose was to determine if plasma and meibum cholesteryl esters (CE), triglycerides (TG), ceramides (Cer) and sphingomyelins (SM) change in a mouse model of diet-induced obesity where mice develop dyslipidemia. METHODS: Male C57/BL6 mice (8/group, age = 6 wks) were fed a normal (ND; 15% kcal fat) or an obesogenic high-fat diet (HFD; 42% kcal fat) for 10 wks. Tear production was measured and meibography was performed. Body and epididymal adipose tissue (eAT) weights were determined. Nano-ESI-MS/MS and LC-ESI-MS/MS were used to detect CE, TG, Cer and SM species. Data were analyzed by principal component analysis, Pearson's correlation and unpaired t-tests adjusted for multiple comparisons; significance set at p ≤ 0.05. RESULTS: Compared to ND mice, HFD mice gained more weight and showed heavier eAT and dyslipidemia with higher levels of plasma CE, TG, Cer and SM. HFD mice had hypertrophic meibomian glands, increased levels of lipid species acylated by saturated fatty acids in plasma and meibum and excessive tear production. CONCLUSIONS: The majority of meibum lipid species with saturated fatty acids increased with HFD feeding with evidence of meibomian gland hypertrophy and excessive tearing. The dyslipidemia is associated with altered meibum composition, a key feature of MGD.

Dyslipidemia and Meibomian Gland Dysfunction: Utility of Lipidomics and Experimental Prospects with a Diet-Induced Obesity Mouse Model.

Meibomian gland dysfunction (MGD) is the leading cause of dry eye disease and loss of ocular surface homeostasis. Increasingly, several observational clinical studies suggest that dyslipidemia (elevated blood cholesterol, triglyceride or lipoprotein levels) can initiate the development of MGD. However, conclusive evidence is lacking, and an experimental approach using a suitable model is necessary to interrogate the relationship between dyslipidemia and MGD. This systematic review discusses current knowledge on the associations between dyslipidemia and MGD. We briefly introduce a diet-induced obesity model where mice develop dyslipidemia, which can serve as a potential tool for investigating the effects of dyslipidemia on the meibomian gland. Finally, the utility of lipidomics to examine the link between dyslipidemia and MGD is considered.

A Hue-Value method for semi-automated assessment of Lid Wiper Epitheliopathy.

BACKGROUND: Lid wiper epitheliopathy (LWE) is a marker of an abnormal lid/cornea interaction. This study proposes an automated Hue-Value grading algorithm of LWE staining following manual selection of the region of interest. METHODS: Images of LWE staining were processed using Hue and Value from HSV (Hue-Saturation-Value) color space with a custom MATLAB program. Thirty-one images were successfully analyzed. Examiners analyzed images in random order twice, separated by more than a week. Bland Altman and Intraclass Correlation Coefficients (ICC) were performed. RESULTS: There was no difference (p > 0.05) between upper (UL) and lower (LL) eyelids for LWE height (UL: 0.12 ± 0.12 mm, LL: 0.12 ± 0.07 mm), width (UL: 10.70 ± 3.84 mm, LL: 10.26 ± 3.49 mm), or area (UL: 2.85 ± 2.67 mm2, LL: 2.63 ± 1.71 mm2). There was no between examiner difference for all eyelid LWE height or area (p > 0.05), but a difference in LWE width (0.16 mm; p = 0.031). ICC for LWE height, width and area were 0.996 (95% CI: 0.993 to 0.998), 0.997 (95% CI: 0.992 to 0.998) and 0.999 (95% CI: 0.998 to 0.999). There was no between examiner difference for height or area (p > 0.05) for UL, but a difference in LWE width (0.28 mm; p = 0.026). ICC for height, width and area were 0.999 (95% CI: 0.996 to 1.00), 0.995 (95% CI: 0.982 to 0.999) and 1.00 (95% CI: 0.999 to 1.00). There was no difference in LWE height, width or area for LL (all p > 0.05). ICC were 0.991 (95% CI: 0.973 to 0.997) for height, 0.998 (95% CI: 0.995 to 0.999) for width and 0.997 (95% CI: 0.990 to 0.999) for area. CONCLUSIONS: This novel method results in highly repeatable interexaminer measures of LWE staining after general lid region delineation. Small differences in LWE width were observed between examiners.