Purchase this article with an account.
Keshia S. Elder, Roderick Fullard, Karin Tran, Nicole Guyette, Pearl Shin, Barry Curtis; Tear Cytokine Profiles and Conjunctival Cytokine Expression in Normal and Dry Eye Patients. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3801.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study is to determine the concentration of inflammatory markers, cytokines, in the non-stimulated tears of normal and aqueous tear-deficient dry eye dry eye (ADDE) patients and determine whether the expression of these cytokines can be detected in cells collected with conjunctival impression cytology (CIC).
Patients were classified as non-ADDE or ADDE. Tear samples were collected from each eye with a sterile flame-polished borosilicate glass micropipette (Drummond Scientific, Broomall, PA) at a consistent rate not exceeding 0.33 µL per minute. After anesthesia with two drops of 0.5% topical ophthalmic proparacaine, conjunctival surface cells were collected from each eye using conjunctival impression cytology. Tear samples were assayed for cytokines using the cytometric bead based assay method with a Bio-Rad 27-Plex Human Cytokine Assay Kit (Bio-Rad, Hercules, CA). Quantitative polymerase chain reaction (qPCR) was performed on the RNA that was extracted from conjunctival surface cells. The cycle threshold of the cytokines of interest (IL-1β, IL-2, IL-2Rβ, IL-6, IL-8, IL-10, CXCL10, IFN-γ, TNF-α) and the reference genes (HPRT1, GAPDH, ACTB) were determined. The cycle thresholds were compared to determine the relative levels of RNA expression.
The Mann-Whitney U Statistic of the tear assays of 7 non-ADDE patients and 4 ADDE patients found statistically significant differences in the levels of tear cytokines IL-8 and VEGF. The student’s t test found no statistically significant difference in the cycle threshold of the nine cytokines expressed on the ocular surface in the non-ADDE and ADDE patients, however, irrespective of the reference gene(s) used to normalize the date, IL-6 and TNF-α were consistently upregulated in the ADDE patients. CXCL10 was upregulated the least among the cytokines investigated.
The expression of the cytokines IL-1β, IL-2, IL-2Rβ, IL-6, IL-8, IL-10, CXCL10, IFN-γ, and TNF-α was successfully detected in cells collected with CIC. Although the relative expression of the cytokines on the ocular surface were not always consistent with the levels of the cytokines in the tears, it appears to be a viable method to detect inflammation on the ocular surface.
This PDF is available to Subscribers Only