Quercetin improves lacrimal gland function through its anti-oxidant actions: Evidence from animal studies, and a pilot study in healthy human volunteers.

Anti-oxidant properties of polyphenols have been gaining medical attention as a preventive factor against aging and/or lifestyle diseases. In this study, we examined the anti-oxidant activity of quercetin improved tear function through its effects on the lacrimal gland in mice and humans. Six week-old diabetic mice, a model for decreased tear production, were fed for 12 weeks ad libitum with an experimental diet containing 0.5% quercetin. As a result, the tear volume was significantly improved compared to the control, despite no changes in body weight, food intake, lacrimal gland morphology or biochemical serum parameters. Moreover, significantly higher SOD-1 and SOD-2 protein levels were detected in the lacrimal glands of quercetin-treated mice by western blot. In addition, quercetin treatment of mouse corneal cell lines exposed to oxidative stress resulted in dose-dependent inhibition of ROS production and enhanced cell survival. Finally, we examined quercetin pharmacokinetics, specifically its presence in serum and tears subsequent to onion consumption in healthy volunteers, and found that the distribution of quercetin and its metabolite shifted from serum to tear following onion intake. An improvement in tear film stability also resulted following the intake by these healthy volunteers of a new, quercetin-rich onion cultivar ("Quergold") in powder form. These results suggested that quercetin improved tear function through its effects on the lacrimal gland in mice and humans.

Compensatory increases in tear volume and mucin levels associated with meibomian gland dysfunction caused by stearoyl-CoA desaturase-1 deficiency.

The stearoyl-CoA desaturase (SCD) family of enzymes catalyzes monounsaturated fatty acid synthesis by inserting a cis double bond at the Δ9 position of saturated fatty acids. Disruption of these enzymes has been reported to induce a severe dry skin phenotype. Since lipid abnormalities in the meibomian glands have been associated with dry eye, we analyzed selected eye tissues contributing to tear volume and composition in genetically SCD-1-deficient mice (SCD-1 KO), including the lacrimal glands and conjunctiva. Previous histopathological analysis had revealed atrophy and loss of meibomian glands; taken together with the increased goblet cell and MUC5AC expression in the conjunctiva reported here, these findings suggest that the tear volume and mucin levels secreted are enhanced in the absence of lipid secretion as a compensatory mechanism. The expression of lipid metabolism genes in lacrimal glands was decreased in SCD1 KO mice. Thus, these results provide new pathophysiological mechanisms to pursue with regard to meibomian gland dysfunction. In addition, lack of SCD-1 causes a compensatory increase in the tear volume and mucin levels associated with changes in expression of lipid metabolism genes. These results may be useful as a new concept for dry eye treatment strategies.

Alteration of tear mucin 5AC in office workers using visual display terminals: The Osaka Study.

IMPORTANCE: There are limited reports on the relationship between mucin 5AC (MUC5AC) concentrations in tears, working hours, and the frequency of ocular symptoms in visual display terminal (VDT) users. This investigation evaluated these relationships among patients with dry eye disease (DED) and individuals serving as controls. OBJECTIVE: To determine the relationship between MUC5AC concentration in the tears of VDT users based on the diagnosis of DED and frequency of ocular symptoms. DESIGN, SETTING, AND PARTICIPANTS: An institutional, cross-sectional study was conducted. Participants included 96 young and middle-aged Japanese office workers. Both eyes of 96 volunteers (60 men and 36 women) were studied. Participants working in a company that used VDTs completed questionnaires about their working hours and the frequency of ocular symptoms. Dry eye disease was diagnosed as definite or probable, or it was not present. Tear fluid was collected from the inferior fornix after instillation of 50 µL of sterilized saline. The MUC5AC concentration was normalized to tear protein content and expressed as MUC5AC (nanograms) per tear protein (milligrams). The differences in MUC5AC concentration between DED groups, between VDT working hours (short, intermediate, and long), and between symptomatic and asymptomatic groups were evaluated with 95% CIs based on nonparametric Hodges-Lehmann determination. MAIN OUTCOMES AND MEASURES: Ocular surface evaluation, prevalence of DED, and MUC5AC concentration. RESULTS: The prevalence of definite and probable DED was 9% (n = 9) and 57% (n = 55), respectively. The mean MUC5AC concentration was lower in the tears of VDT users with definite DED than in those with no DED (P = .02; Hodges-Lehmann estimator, -2.17; 95% CI, -4.67 to -0.30). The mean MUC5AC concentration in tears was lower in the group that worked longer hours than in the group that worked shorter hours (P = .049; estimated difference, -1.65; 95% CI, -3.12 to 0.00). Furthermore, MUC5AC concentration was lower in participants with symptomatic eye strain than in asymptomatic individuals (P = .001; estimated difference, -1.71; 95% CI, -2.86 to -0.63). CONCLUSIONS AND RELEVANCE: The data obtained in the present study suggest that office workers with prolonged VDT use, as well as those with an increased frequency of eye strain, have a low MUC5AC concentration in their tears. Furthermore, MUC5AC concentration in the tears of patients with DED may be lower than that in individuals without DED.

A shift of the TOR adaptor from Rictor towards Raptor by semaphorin in C. elegans.

The target of rapamycin (TOR), a central regulator for cell growth and metabolism, resides in the two functionally distinct complexes TORC1 and TORC2, which are defined by their adaptors Raptor and Rictor, respectively. How the formation of the two TORCs is orchestrated remains unclear. Here we show the control of TOR partnering by semaphorin-plexin signalling in Caenorhabditis elegans. In semaphorin and plexin mutants, TOR-Raptor association decreases whereas TOR-Rictor association increases, concomitantly with TORC1 down- and TORC2 up-regulation. Epidermal defects in the mutants are suppressed by inhibiting TORC2 or reinforcing TORC1 signalling. Conversely, inhibition of TORC1 signalling phenocopies the mutants. Thus, our results indicate that TORC formation is a singularly important step in semaphorin signalling that culminates in diverse outcomes including TORC1-promoted messenger RNA translation and TORC2-regulated cytoskeletal remodelling.