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Rosa Corrales, Stephen Pflugfelder; Regulators of MUC5AC gene expression in conjunctival epithelia of dry eye patients. Invest. Ophthalmol. Vis. Sci. 2013;54(15):913.
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© ARVO (1962-2015); The Authors (2016-present)
T helper (Th) cytokines and transcription factors have been found to modulate goblet cells differentiation and morphology in mice. We investigated expression of T helper 1 (Th1) and Th2 cytokine receptors and transcription factors in the conjunctival epithelia of a dry eye population and compared them with healthy subjects.
Conjunctival impression cytology (CIC) samples were obtained from 16 dry eye patients (tear deficient with a Schirmer-1 score < 5mm wetting in 5 minutes) and 13 healthy subjects. RNA was extracted, cDNA synthesized and real-time PCR performed using Taqman probes to evaluate expression of the following genes: MUC5AC, keratin 7 (K7), forkhead box protein A2 (FOXA2), SAM pointed domain-containing Ets transcription factor (SPDEF), Krueppel-like factor 4 (KLF4), IFN-γR, IL-13-Ra1 and IL13Ra2. The housekeeping gene hypoxanthine phosphoribosyltransferase 1(HPRT-1) was amplified to normalize levels of expression. No template controls and RNA were studied for evidence of contamination. Results were analyzed using the comparative Ct method using values from healthy subjects as calibrator. The student t-test for independent samples was used to compare means between groups.
FOXA2 expression was below the level of detection. K7 and MUC5AC transcripts were decreased in dry eye samples. Expression of the IL-13 signaling receptor (IL-13Rα1) and SPDEF were unchanged, while expression of the IL-13 decoy receptor, IL-13Rα2, as well as IFN-γR and KLF4 were significantly increased in the dry eye conjunctival epithelium.
These results indicate that dry eye disrupts signaling pathways in the conjunctival epithelium that are involved in goblet ells differentiation, resulting in decreased signaling by the Th2 cytokine Il-13 and increased signaling by the Th1 cytokine IFN-γ. Expression of the goblet cell transcription factor KLK4 increased.
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