Vitelline membrane outer layer 1 homolog interacts with lysozyme C and promotes the stabilization of tear film.

PURPOSE: The aim of this study was to explore the possible interactions between vitelline membrane outer layer 1 homolog (VMO1) and other tear proteins and to determine the function of VMO1 in tear fluid.

METHODS

Interactions between recombinant human VMO1 and several abundant tear proteins were determined by dot blot, His pull-down, immunoprecipitation, and Western blot assays, as well as by computer-assisted prediction and modeling of molecular interactions. Kirby-Bauer antibiotic testing was performed to determine whether VMO1 possesses antimicrobial activity. Tear samples were collected from dry eye patients and from healthy controls. The role of VMO1 in maintaining the stability of tear film was investigated by measurement of contact angles on Teflon, tear break-up time (TBUT) and the time-dependent reduction in tear film integrity in mice.

RESULTS

Vitelline membrane outer layer 1 homolog showed an interaction with lysozyme C (LYSC) in the dot-blot, His pull-down, and immunoprecipitation assays. Vitelline membrane outer layer 1 homolog revealed no zones of growth inhibition of standard strains of Staphylococcus aureus and Escherichia coli. Tears presented smaller contact angles on Teflon surfaces after the addition of VMO1 (P<0.05). Vitelline membrane outer layer 1 homolog-treated mice showed longer TBUTs (P<0.05). Tear films from VMO1-treated mice maintained their integrity for longer periods of time than tear films from the control group, and this effect was dose-dependent.

CONCLUSIONS

Vitelline membrane outer layer 1 homolog interacts with LYSC and has positive effects on the stabilization of tear film.