Conjunctival Cytokine Expression in Symptomatic Moderate Dry Eye Subjects

Srihari Narayanan, William Miller, Alison McDermott

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67 Citations (Scopus)


Purpose - To compare ocular surface cytokine expression in healthy controls and subjects with moderate dry eye and to study the ability of interleukin (IL)-1β to modulate cytokine expression in cultured human conjunctival epithelial cells (CECs). Methods - Subjective (symptom questionnaire) and objective (tear osmolality, fluorescein tear break-up time [TBUT]) measures of dry eye were determined in five healthy controls and five subjects with moderate dry eye. Tear clearance rates were measured with a fluorophotometer. Enzyme immunoassay and a cytokine bead assay were used to quantify IL-1β in tear fluid. RT-PCR was performed to detect expression of IL-1β, IL-6, IL-8, growth-related oncogene (GRO)-β, intercellular adhesion molecule (ICAM)-1, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and ephrin A5 in conjunctival impression cytology (CIC) samples and in CECs (IOBA-NHC cell line, n = 3; primary cultured CEC, n = 3) exposed to 10 ng/mL IL-1β for 6 hours. Results - Subjects with moderate dry eye had significantly higher symptom scores, higher tear osmolality, and shorter TBUT than healthy controls. Subjects with dry eye demonstrated slightly slower tear clearance (13.1% per minute) than healthy controls (15.4% per minute). Very low levels of IL-1β protein were detected in the tear fluid of both groups. TRAIL was constitutively expressed in CIC samples, whereas IL-1β, IL-6, and GRO-β were absent. Weak expression of IL-8 (two healthy, four dry eye), ICAM-1 (four healthy, four dry eye), and ephrin A5 (one healthy, two dry eye) was observed. IL-1β upregulated its own expression and that of IL-6, IL-8, GRO-β, and ICAM-1 in cultured CECs but not that of ephrin A5 or TRAIL. Conclusions - The lack of major differences in ocular surface cytokine expression between the two groups of subjects implies other inflammatory pathways or etiologies are involved in moderate dry eye. Although IL-1β modulated the expression of various cytokines in cultured CECs, its absence in tear fluid and CIC samples suggests that IL-1β does not play a modulatory role in moderate dry eye.
Original languageEnglish
Pages (from-to)2445-2450
JournalInvestigative Opthalmology & Visual Science
Issue number6
Publication statusPublished - Jun 2006


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