Vitamin D Induces Global Gene Transcription in Human Corneal Epithelial Cells : Implications for Corneal Inflammation

• PURPOSE. Our previous studies show that human corneal epithelial cells (HCEC) have a functional vitamin D receptor (VDR) and respond to vitamin D by dampening TLR-induced inflammation. Here, we further examined the timing of the cytokine response to combined vitamin D-TLR treatment and used genome-wide microarray analysis to examine the effect of vitamin D on corneal gene expression. METHODS. Telomerase-immortalized HCEC (hTCEpi) were stimulated with polyinosinicpolycytidylic acid (poly[I: C]) and 1,25-dihydroxyvitamin D-3 (1,25D(3)) for 2 to 24 hours and interleukin (IL)-8 expression was examined by quantitative (q) PCR and ELISA. Telomeraseimmortalized HCEC and SV40-HCEC were treated with 1,25D(3) and used in genome-wide microarray analysis. Expression of target genes was validated using qPCR in both cell lines and primary HCEC. For confirmation of IjBa protein, hTCEpi were treated with 1,25D(3) for 24 hours and cell lysates used in an ELISA. RESULTS. Treatment with 1,25D(3) increased poly(I: C)-induced IL-8 mRNA and protein expression after 2 to 6 hours. However, when cells were pretreated with 1,25D(3) for 24 hours, 1,25D(3) decreased cytokine expression. For microarray analysis, 308 genes were differentially expressed by 1,25D(3) treatment in hTCEpi, and 69 genes in SV40s. Quantitative (q) PCR confirmed the vitamin D-mediated upregulation of target genes, including nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (I kappa B alpha). In addition to increased transcript levels, I kappa B alpha protein was increased by 28% following 24 hours of vitamin D treatment. CONCLUSIONS. Microarray analysis demonstrates that vitamin D regulates numerous genes in HCEC and influences TLR signaling through upregulation of I kappa B alpha. These findings are important in dissecting the role of vitamin D at the ocular surface and highlight the need for further research into the functions of vitamin D and its influence on corneal gene expression.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

vitamin D

cornea

inflammation

toll-like receptors

microarray

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)