Scientists Discovered Lacritin — A Tear Gland Protein That Boosts Tear Secretion

The researchers used cDNA and genomic cloning techniques to identify and characterize the lacritin gene. They examined mRNA and protein expression across more than 50 human tissues using in situ hybridization and immunohistochemistry. Functional studies used overnight cultures of rat lacrimal acinar cells to test lacritin's secretion-enhancing effects, and recombinant lacritin was applied to measure its impact on ductal cell proliferation and corneal epithelial cell signaling.

Dry eye disease affects hundreds of millions of people worldwide, and current treatments mostly just supplement tears rather than addressing the underlying biology. The discovery of lacritin — a naturally occurring protein that specifically enhances tear production — opens a potential therapeutic avenue for treating dry eye at its source by restoring the gland's own secretory function.

Lacritin's discovery filled a significant gap in understanding how the lacrimal gland maintains tear production. Since its identification in 2001, subsequent research has explored lacritin as a potential therapeutic for dry eye disease, including studies on topical lacritin formulations. It represents a broader shift toward treating secretory dysfunction by targeting the gland's own regulatory proteins rather than just replacing the missing fluid.

This is a discovery and characterization study using cell culture systems and animal tissue, not a clinical trial. The secretion-enhancing effects were demonstrated in overnight cultures of rat acinar cells, which may not fully reflect in vivo human biology. The study establishes lacritin's existence and basic functions but does not test therapeutic applications. The tissue expression survey, while broad, relied on available human tissue samples.