Clinical analysis of interleukin-6 level in tear and serum of dry eye patient

Abstract

Background Mechanism of dry eye disease has not been established clearly.Some increasing evidences showed that inflammation plays an important role in pathogenesis and development of dry eye disease.However,the association of interleukin-6 (IL-6) with dry eye has not been clarified.Objective This study was to assess the correlation of IL-6 levels in tear and serum of patient with dry eye disease and clinical symptom.Methods Twenty patients with Sj（o）gren syndrome (SS) and 20 cases with non-Sj（o）gren syndrome (NSS) were enrolled from Second Affiliated Hospital of Nanjing Medical University,and 20 healthy volunteers were recruited as the normal controls.Symptom questionnaires were self-answered and multiple dry eye-related clinical tests were performed,including tear film breakup time (BUT),Schirmer Ⅰ test (S Ⅰ t) and corneal fluorescence staining.IL-6 concentrations in serum and tear were detected by enzyme-linked immunosorbent assay (ELASA).The correlation between IL-6 level and tear film and ocular surface parameters was analyzed by Spearman rank correlation.Written informed consent was obtained from each subject initial of this trial.Results The scores of symptom questionnaires were 18.50 (11.75,23.00),23.00 (19.00,32.00) and 2.00 (0.25,4.00) in the SS group,NSS group and the normal control group,and significantly increasing values were seen in the SS group and NSS group compared with the normal control group (P=0.00,0.00).BUT values in the SS group and NSS group were 2.50 (2.00,3.88) seconds and 3.50 (2.13,4.00) seconds and were lower than 15.00 (13.13,17.00) seconds in the normal control group (P=0.00,0.00).S Ⅰ t values in the SS group,NSS group and the normal control group were 2.00 (1.50,2.88),4.00 (3.00,5.75) and 19.00 (18.00,25.00)mm,showing significant differences between the SS group and the normal control group (P =0.00),the SS group and the NSS group (P =0.00) or the NSS group and the normal control group (P=0.00).The marked elevation of keratoepithelioplasty score was seen between the SS group and the normal control group (5.75 (4.00,7.75) vs.0.00 (0.00,0.75) (P =0.00) or the NSS group and the normal control group (4.50(3.63,6.00) vs.0.00(0.00,0.75)) (P=0.00).Concentrations of IL-6 in serum and tear in the SS group,NSS group were (131.47±21.04) μg/L and (77.81 ± 15.68) μg/L and were significantly higher than (31.62±8.57) μg/L of the normal control group,and those in the tear were (33.44±8.01) μg/L,(18.78 ±5.73) μg/L and (8.77 ± 3.43)μg/L,respectively in the three groups,with a significant reduce in the normal control group (all P=0.00).tL-6 levels in serum and tear were positively correlated with the score of symptom questionnaires or keratoepithelioplasty and negatively correlated with BUT and S Ⅰ t (all P =0.00).Conclusions IL-6 levels in the tear and serum of the dry eye patient are associated with the severity of the disease.IL-6 levels in serum and tear may be objective,sensitive and reliable indicators of dry eye. Key words: Dry eye; Inflammation; Cytokine; Interleukin-6 ; Enzyme-linked immunosorbent assay