Integrating Transcriptomics and Proteomics of Human Lacrimal Gland and Tear Fluid

Abstract

Purpose: : The aim of this study is to integrate transcriptomics and proteomics for the profiling of lacrimal gland and tear fluid. This approach was applied to assess the biochemical changes in tear fluids and lacrimal gland tissues from lacrimal gland adenoid cystic carcinoma patients.

Methods: : Tear fluid was collected using Schirmer strip from one lacrimal gland adenoid cystic carcinoma patient (age: 22, male) before surgery. Tear proteins were eluted from Schirmer strip, tryptic-digested and analyzed by two dimensional nanoLC-MS/MS (Q-STAR). For comparison, gene expression of lacrimal gland tumor tissue was examined using cDNA microarray (Affymetrix Gene 1.0 ST array). Proteomic analysis was also performed on lacrimal gland tumor tissue using shotgun two dimensional nanoLC-MS/MS. Transmission electron microscopy (TEM) was used to confirm the presence of acinar cells in the lacrimal gland tumor tissue.

Results: : In total 81 proteins from tear fluid and 190 proteins from lacrimal gland tumor tissue were identified using shotgun proteomic analysis. Twenty tear proteins were also seen in the lacrimal gland tumor tissue. Tear proteomics revealed the presence of a high level of matrix metalloproteinase-9 (MMP-9) in tear fluid of the affected eye. With this proteomic approach, the signal from mass spectrometry (MS) for MMP-9 is typically undetectable in normal tears because of its very low concentration. Microarray data correlated well with the proteomic data of lacromal gland tumor tissue where MMP-9 was also seem to be upregulated.

Conclusions: : We have demonstrated that tear fluid may be useful for diagnosing and monitoring lacrimal gland diseases. A comprehensive genomic and proteomic profiling may lead to develop novel diagnostics and therapeutics.

Keywords: lacrimal gland • cornea: tears/tear film/dry eye • proteomics