Tear total protein analysis in patients with late sulfur mustard-induced ocular complications: a cross-sectional study

Abstract

Background: Eyes are the most sensitive organs to sulfur mustard (SM). Late ocular complications have been reported even 15-20 years post-exposure. To date, no study has investigated the composition of tear proteins in tear samples of SM-intoxicated patients. Methods: Total protein content as well as concentrations of vascular endothelial growth factor (VEGF), calcitonin gene related peptide (CGRP) and substance P were measured in unstimulated tears of chemically-injured patients who suffer from late ocular complications of SM. These levels were compared to corresponding values obtained from tears of healthy control subjects. The concentration of total proteins was measured using the Bradford method and those of VEGF, CGRP and substance P by ELISA. Results: Total protein concentration was significantly lower in tears of the SM compared to control group (p < 0.01). In contrast, tear samples of the SM group had significantly higher VEGF and VEGF/total protein compared to control group (p < 0.01). Tear CGRP concentration was found to be lower in the SM vs. control group (p < 0.05) but no significant difference in CGRP/total protein was observed (p > 0.05). Finally, tear substance P concentrations were not found to be significantly different between the two groups (p > 0.05). Conclusion: The results of this investigation indicated decreased total protein and CGRP, and elevated VEGF concentration in tears of SM-intoxicated patients who suffer from chronic ocular complications.