Upregulated expression of –defensins in the tears of pterygium patients

Abstract

Abstract: : Purpose: To determine if defensins are found in the tear film of patients with pterygium. Methods: Tear samples were collected with 10 µl pipettes with fire polished tips from patients (n= 15, 12 male, 3 female, average age: 53) prior to pterygium surgery from diseased eyes and fellow normal control eyes. Tear protein profiles were compared using surface enhanced laser desorption/ionization–time of flight (SELDI–TOF) ProteinChip technology. Confirmation of the identity of the α–defensins in human tears was made by liquid chromatography (LC) purification, trypsin digestion and electrospray (ESI) tandem mass spectrometry (MS) analysis of tryptic digests. LC–ESI–MS was used to quantify the levels of human α–defensins (HNP–1 and HNP–2) in human tears by monitoring the ions at m/z = 861.5 for HNP–1 and m/z = 844.0 for HNP–2. Results: With this proteomic approach, one of the obvious changes we found was that a group of human α–defensins (HNP–1, HNP–2 and HNP–3) was significantly up–regulated in the tear fluid of pterygium affected eyes when compared with the fellow normal eyes. The identity of these three human α–defensins was confirmed by sequencing the peptides using tandem mass spectrometry. The mean concentration (n = 5) of α–defensins for pterygium eyes and fellow control eyes were 1.33 ± 0.47 µg/ml (HNP–1, pterygium eye, p < 0.015), 0.61 ± 0.23 µg/ml (HNP–2, pterygium eye, p < 0.012) and 0.17 ± 0.12 µg/ml (HNP–1, control eye), 0.02 ± 0.02 µg/ml (HNP–2, control eye) respectively. Conclusions: The upregulated expression of the α–defensins in tear fluids of pterygium patients indicates that this class of peptides may be part of the response of the ocular surface to the formation of this fibrovascular tissue or the accompanying inflammation.

Keywords: Pterygium • inflammation • proteomics