Expression of Th17 related cytokines on ocular surface of dry eye and its significance

Abstract

Background The pathogenesis of dry eye has not been clearly established.There are more and more evidences to suggest that it is associated with ocular surface inflammation mediated by immunity.But how T helper cell 17 (Th17) plays its role in dry eye remains unclear.Objective The aim of this study was to investigate the expressions of Th17 related cytokines in ocular surface with dry eye.Methods A prospective cohortl study was designed.This protocol was approved by Ethic Commission of Peking University Third Hospital,and written informed consent was obtained from each subject prior to entering this cohort.Twenty female patients with Sjigren syndrome (SS group),20 patients with non-SS dry eyes and 20 normal volunteers were recruited in Peking University Third Hospital during 2011-2012 duration and all the subjects were menopausal female with the age 50 years old or more.The ocular surface disease index (OSDI)questionnaire designed by Schiffman was performed firstly,and then tear breakup time (BUT),corneal fluorescein staining and Schirmer Ⅰ test (S Ⅰ t) were carried out in the subjects.Expression of Th17 related cytokines mRNA were measured using PCR-Array.The correlation between IL-17A and ocular surface parameters was analyzed.Results The OSDI scores of the SS dry eye group,non-SS dry eye group and normal control group were 50.00 (33.50,66.50),45.00 (35.50,55.00) and 3.00 (0.00,5.00),the S Ⅰ t values were 2.50 (1.00,4.00),5.00 (2.00,5.00) and 15.50 (10.00,18.50),the BUT were 2.00 (1.00,4.00),4.00 (3.00,5.00) and 10.00 (10.00,12.00),the corneal fluorescein staining score were 8.50 (6.00,12.00),5.50 (4.00,7.00)and 0.00 (0.00,0.00),respectively,and significant differences were seen among the SS group,non-SS dry eye group and normal control group (x2=34.11,28.13,93.66,92.25,all at P＜0.01).The relative expression values of IL-17A mRNA,IL-6 mRNA,IL-8 mRNA,IL-22 mRNA and IL-23 mRNA in the ocular surface were 1.98±0.16,11.64±1.32,6.67±1.12,1.88±0.18 and 1.78±0.17 in the SS group patients,and 1.45±0.17,1.32±0.14,1.12 ±0.13,1.23 ±0.15 and 1.23 ±0.13 in the non-SS dry eye group patients,respectively,with significant differences between the two groups (all at P＜0.01).IL-17A level on the ocular surface was significantly negative correlated with BUT (r =-0.56,P＜0.01) and positive correlation with corneal fluorescein staining scores (r=0.44,P=0.01).Conclusions Expressions of Th17 related cytokines in the ocular surface increased in patients with dry eye,especially in those with SS.IL-17A level in ocular surface is associated with BUT and corneal fluorescein staining scores,suggesting that immune is involved in the pathogenesis and devlopment of dry eye. Key words: Dry eye; Sj(o)gren syndrome; Immunity; CD4-positive T-lymphocyte; Cytokine; Inflammation; Female; Prospective study