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Piera Versura, Manuela Piazzi, Giuseppe Giannaccare, Michela Fresina, Veronica Forlani, Lucio Cocco, Emilio C Campos; Sex related difference in tear protein profile and cytokine expression begin at a young age in humans. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3933.
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A systematic analysis on tears by gender and age in healthy individual subjects has not been performed to date. To evaluate tear proteins and cytokine expression in healthy young males and females, these collected in different phases of the menstrual cycle
10 μl unstimulated tears were collected in both eyes from healthy volunteers, 25 males (M) and 25 females (F), aged 20-24 yrs. Only females who reported regular cycle (26-34 days) were included and sampling occurred at day 12±2 (high estrogen, H-E i.e., follicular phase) and day 28±2 (low estrogen, L-E i.e., premenstrual phase). Protein analysis was performed in individual samples with the 2100 Bioanalyzer (Agilent Technology, CA, USA), 1-D SDS-PAGE electrophoresis and characterized by western blotting. Total protein content (TP) and the following proteins were recognized and quantified: Lysozyme-C (LYS-C), Lactotransferrin (LACTO), exudated serum albumin (ALB), Serotransferrin (TRANSF),Tear lipocalin 1 (LIPOC-1), Zinc-alpha-2-glycoprotein (ZAG-2), Lacritin (LACRT ) and Protein-rich-protein 4 (PRR4). IL-1β, IL-6, IL-8, TNF-α and MMP-9 were detected by multiplex-bead assay (Luminex, Biorad Bio-Plex 100). Data were statistically compared (significance p<0.05)
Results were consistent in all samples, with a reduced variability among subjects in both M and F. Data from both eyes in each subject were highly correlated. Statistically significant lower level for all the proteins was found in M as compared to F in both phases, whereas no difference between phases of the cycle in F was demonstrated, except for LACRT that showed higher levels in M versus F and in L-E versus H-E (p<0.001). IL-1β and TNF-α showed expression levels below the minimum detectable level in all subjects, no sex related difference was found for IL-6, IL-8 level was higher in M with no difference between phases of the cycle in F, and MMP-9 level was the highest in M with higher level in H-E versus L-E phase in F
The level of major tear proteins significantly differs with respect to the sex also in the youngest and without any systemic or ocular function impairment. The hormonal fluctuation over the menstrual cycle appears to influence LACRT and MMP-9 levels in the normal and young females, with a potential impact on the homeostasis of the lachrymal function system with advancing age. Commercial disclosure: none
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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