BackgroundThe pathogenesis of allergic conjunctivitis has not been clearly established.Current researchers indicate that interleukin-4 (IL-4), IL-5 and IL-13 may play an important role in allergic conjunctivitis.But whether the roles of these inflammatory factors are same in different types of allergic conjunctivitis remains unclear.

ObjectiveThis study was to investigate the expressions of IL-4, IL-5 and IL-13 in ocular surface with different types of allergic conjunctivitis.

MethodsA prospective cohort study was designed.Eighty individuals were recruited in Shanxi Eye Hospital from April 2013 to September 2014, including 20 patients with vernal keratoconjunctivitis (VKC), 20 patients with seasonal allergic conjunctivitis (SAC), 20 patients with perennial allergic conjunctivitis (PAC) and 20 normal healthy subjects.Surficial tissues were binocularly scraped using disinfected scraper from upper eyelid conjunctiva, and 4 μl of tear fluid was obtained with capillary tube.The expressions of IL-4, IL-5 and IL-13 protein and mRNA in the conjunctival epithelial cells were detected by immunohistochemistry and real-time fluorescence quantitative PCR.The IL-4, IL-5 and IL-13 concentrations in tear fluid were assayed by Luminex method.This study complied with Declaration of Helsinki and the research protocol was approved by the Shanxi Eye Hospital Ethics Committee.Written informed consent was obtained from each subject prior to entering the cohort.

ResultsIL-4, IL-5 and IL-13 were positively expressed in cytoplasm of conjunctival epithelial cells in the VKC group, SAC group and PAC group, but the expressions of IL-4, IL-5 and IL-13 were absent in the normal control group.The relative expression levels of IL-4 mRNA were 4.11±1.24, 2.71±0.71 and 2.00±0.80; the relative expression levels of IL-5 mRNA were 4.02±0.43, 2.07±0.45 and 1.47±0.50; and the relative expression levels of IL-13 mRNA expression levels were 6.44±0.66, 4.35±1.26 and 2.39±0.86 in the VKC group, SAC group and PAC group, showing significant differences among the 4 groups ( F=51.32, 220.18, 162.49, all at P<0.01). The relative expression levels of IL-4, IL-5 and IL-13 mRNA were significantly higher in the VKC group than those in the SAC group and PAC group; and those in the SAC group were significantly elevated in comparison with the PAC group (all at P<0.05). No IL-4, IL-5 and IL-13 were detected in the tear fluid in the normal control group; while the concentrations of IL-4, IL-5 and IL-13 in the tear fluid were (14.06±3.50), (10.88±1.82) and (34.28±8.42) pg/ml in the VKC group, and (7.71±0.65), (5.10±1.33), (23.77±6.29) pg/ml in the SAC group as well as (3.30±1.50) pg/ml, (2.43±1.28) pg/ml and (17.67±4.28) pg/ml in the PAC group, showing significant differences among the 3 groups ( F=200.29, 260.49, 128.23, all at P<0.01). IL-4, IL-5 and IL-13 concentrations in the tear fluid were significantly higher in the VKC group than those in the SAC group and PAC group, and those in the SAC group were significantly raised in comparison with the PAC group (all at P<0.01).

ConclusionsIL-4, IL-5 and IL-13 participate in the pathogenesis of multiple allergic conjunctivitis, but their expressions in the ocular surficial tissue are discriminatory in different types of allergic conjunctivitis.