Evaluation of the tear and serum levels of IL-8 in sulfur mustard intoxicated patients 20 years after exposure

Abstract

Purpose: Delayed keratitis is the most dangerous ocular complication of sulfur mustard (SM) exposure. This study aimed to evaluate the role of tear and serum levels of interleukin-8 (IL-8) in SM exposed subjects. Design and methods: In this historical cohort study, the experimental group included 370 participants who had been exposed to SM 20 years prior. Data were compared with those of 128 unexposed participants as the control group. After completing a thorough systemic and ocular examination, serum IL-8 levels in all exposed and controls were compared. According to the statistical calculation, tear IL-8 levels, were compared in randomly selected 48 exposed and 37 controls. Based on the ocular findings, the selected subjects were divided into two subgroups, normal subjects include those participants who had no ocular signs and abnormal subjects, were those who had at least one or more ocular signs. Results: Bulbar conjunctiva and limbal tissues evaluation in all participants showed a significantly higher number of abnormalities in exposed group than in the control group (P = 0.004 and P = 0.048 respectively). Serum IL-8 levels in all exposed were significantly lower than the matched controls (P = 0.002). Tear IL-8 levels in the selected exposed were significantly lower than in the selected controls (P = 0.030). In exposed group with normal conditions of the lids, bulbar conjunctiva, cornea, tear status, limbus, slit lamp findings and final ophthalmic assessment, tear IL-8 levels were significantly lower than in the matched controls (P = 0.022, 0.037, 0.027, 0.050, 0.039, 0.029, 0.045 respectively). With respect to the global ophthalmic assessment, tear fluid IL-8 levels in the abnormal controls were significantly lower than in the normal controls (P = 0.049), but this decrease in secretion of tear IL-8 were not encountered in abnormal exposed (P = 0.415). Conclusion: Tear IL-8 secretion was significantly inhibited in the unexposed controls with ocular surface abnormalities, while these inhibitory responses were not encountered in SM-exposed cases with ocular surface abnormalities.