Abstract
Purpose: :
Vernal keratoconjunctivitis (VKC) is a chronic allergic eye disease characterized by multiple mediators, cytokines and protein expression in its inflammatory phase. However, many peptides in human tears have not yet been characterized. The aim of this study was to analyze peptide profiles in human tears by using capillary or nano LC-MALDI Mass Spectrometry (MS) to elucidate compositional differences between healthy subjects and patients affected by VKC.
Methods: :
Tears were collected from 16 active VKC patients and 16 age-matched normal subjects, avoiding the tear reflex. All patients were free of drugs for at least three days and received a full clinical examination including a scoring of allergic/inflammatory signs and symptoms. Peptides and proteins in tears samples were separated by capillary monolithic column and collected with a micro-collector on a MALDI plate or on a multiwell plate. Subsequently, collected fractions were analyzed with a MALDI TOF instrument or digested with trypsin. Tryptic peptides were subsequently analyzed by MALDI TOF-TOF MS.
Results: :
About 50 new peptides (mass/to charge) were identified by LC-MALDI-TOF, many by trypsin digestion and MALDI TOF-TOF MS/MS using Mascot. Several successfully isolated peptides in VKC tears need further quantitative analyses. Most of the defined peptides were in the mass range below 6000 da.
Conclusions: :
This technique was found to be very useful in the characterization of the peptidoma of human tears. Peptides in the mass range below 6000 da are potential ocular biomarkers. Analysis allowed the identification of previously undetected factors in tears of VKC patients.
Keywords: proteomics • conjunctivitis • cornea: tears/tear film/dry eye