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Y. Wei, S. P. Epstein, M. Vallabhajosyula, M. L. Massingale, T. K. Deveney, P. A. Asbell; Evaluation of the Role of sPLA2-IIa in Ocular Surface Inflammation. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5520.
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The human secretory phospholipase A2 of group IIa (sPLA2-IIa) is found at high levels in normal human tears and is believed to function as a bactericidal agent to protect the ocular surface from infection. sPLA2-IIa has also been shown to be significantly increased in tears of patients with inflammatory eye diseases such as dry eye disease (DED). This study was designed to analyze the change in mRNA expression of sPLA2-IIa and inflammatory cytokines in human conjunctival cell culture and in patients.
Conjunctival cell samples from human subjects were collected from 3 DED patients and 3 age matched normals via impression cytology. All participants received and signed Mount Sinai IRB approved informed consent. Samples were collected bilaterally from the superior bulbar and superio-temporal aspects of the conjunctiva. The cell culture samples were from immortalized human conjunctival epithelia cell line (CCL-20.20) treated with placebo alone as control, sPLA2-IIa (10 µg/ml) for 24 hours. Total RNA from these samples was isolated and relative mRNA expression of sPLA2-IIa and inflammatory cytokines was analyzed using a real time PCR. The mRNAs of β-actin and/or GAPDH were applied as internal controls. The RNAs from cell culture samples were also analyzed by a pathway-specific cRNA microarray.
The mRNA expression of sPLA2-IIa from DED patients showed an average of 2-fold increase compared with the normal controls. The mRNA expression of TFN-, IL-1β, IL-6 and IL-8 were also shown to express an average increase of 1.32, 1.72, 2.60, 1.77 fold, respectively, supporting the increased protein levels of these cytokines measured from tears. In human conjunctival epithelia cell culture treated with 10 µg/ml of sPLA2-IIa, sPLA2-IIa expression was up-regulated and expression of TFN-, IL-1β, IL-6, IL-8 were also greatly enhanced compared to controls, as measured by RT-PCR. Using the GEArray, 21 genes were found to be significantly up-regulated and 25 genes were found significantly down-regulated when sPLA2-IIa was added (>1.5-fold compared with control).
Our results strongly suggest that sPLA2-IIa is involved in the immuno-modulation of conjunctival epithelia, especially the inflammatory-related responses. Studies on elucidating the role(s) and mechanism of sPLA2-IIa in ocular surface inflammation, such as in DED, will provide novel therapeutic strategies to treat these diseases. This study was supported by the Martin and Toni Sosnoff Foundation.
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