Identification and relative quantification of differential tear-based proteome alterations affected by Keratoconus.

Keratoconus is an asymmetric condition of corneal thinning that typically occurs in early adulthood and has an estimated prevalence of about 1/2,000 human population. Aimed at revealing alterations in the abundances of tear proteins between two groups of patients and controls, measurements of peptides derived from proteolytic digestion of proteins was performed using one-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry strategy. The results of statistical analysis showed that 42 proteins represented differential expression, of those 28 and 14 proteins indicated decreament and increament in their levels of expression, respectively. Based on the bioinformatics analyses of the differentially expressed tear proteins like gene ontology biological processes, the most affected underlying processes include: cellular processes (27.1%), metabolic processes (20/2%), biological regulation (11/6%), cellular compartment organization (9/3%) and response to stimuli (9/3%). Moreover, gene ontology analysis associated with the cellular localization of this protein subset indicated that a large number of these proteins belonge to the intracellular space. Such proteomic studies can enhance our basic knowledge of biological processes and give rise to a deeper understanding of the disease underlying mechanisms as well as in clinical research to identify potential biomarkers for disease and as drug targets.