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Yi Wei, Karen Fernandez, Neha Gadaria, Peter Dentone, Brittlyn Pearlman, Penny Asbell; Tear Cytokine Profile as a Non-invasive Biomarker of Inflammation for Multicenter Clinic Trials of Ocular Surface Diseases. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6291.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the use of inflammatory cytokine profile of tears of human subjects as a noninvasive biomarker of ocular surface inflammation and for multicenter clinic trials.
Tears from normal subjects (n=13), contact lens wearers (n=10) and dry eye disease patients (n=18) were collected from local and distant clinic sites. Inflammatory cytokine concentrations in tear samples were measured using high sensitive human cytokine multiplex kit from Millipore (Luminex).
The repeatability was evaluated in three ways: (1) Pooled human tears were divided into 3 repeats, each with 5 different dilutions. A total of 11inflammatory cytokines (IL-1β, -2, -4, -5, -6, -8, -10, -12, -13, INF-γ and TNF-α) were analyzed. There’s no statistically significant difference either within the repeats or among the dilutions. (2) Dilution effect: Since, in most dry eye subjects and some normal subjects, only limited tear volume can be collected, dilution of samples with assay buffer is required. To determine a reliable dilution range, pooled tear samples with serial dilutions (from 3 to 156-fold) were evaluated. Similar results were obtained when dilution factors were within 3-20 (corresponding to 15-2.5 μL of tear sample per assay). (3) Standard operating procedure (SOP) was developed using cytokine standards of known concentrations. No statistically significant difference was observed among 6 repeats. The spike recovery was within 80-120% range for all of the cytokines assayed, satisfying the manufacturer’s standards of quality control criteria for Luminex analysis of multiple cytokines. The feasibility was evaluated with tear samples from both local (n=18, all DE) and distant (n=20, 10 contact lens wearers and 10 controls) clinic centers in a masked fashion. At least 5-10 different cytokines, including IL-1β, IL-6, TNF-α, were simultaneously detected from each sample. DE subjects treated with anti-inflammatory agents for 3 months showed a decrease in IL-1β (4-fold) and TNF-α (2-fold), but an increase in IL-6 (3-fold) in comparison with subjects randomized to placebo.
We have established a standard operating procedure in our institute for multicenter clinic trials on human tear cytokine assessment. This study demonstrated that tear inflammatory cytokines, such as IL-1β, IL-6, TNF-α, can be used as biomarkers of inflammation in multicenter clinic trials of ocular surface diseases such as DED. Cytokine biomarkers may provide critical information to fill the gap between clinical treatment modalities and the mechanism(s) involved in DED treatment.
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