title: Vitamin D Induces Global Gene Transcription in Human Corneal Epithelial Cells: Implications for Corneal Inflammation.
abstract: 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.
  
  
  
  Telomerase-immortalized HCEC (hTCEpi) were stimulated with polyinosinic-polycytidylic acid (poly[I:C]) and 1,25-dihydroxyvitamin D3 (1,25D3) for 2 to 24 hours and interleukin (IL)-8 expression was examined by quantitative (q)PCR and ELISA. Telomerase-immortalized HCEC and SV40-HCEC were treated with 1,25D3 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 IκBα protein, hTCEpi were treated with 1,25D3 for 24 hours and cell lysates used in an ELISA.
  
  
  
  Treatment with 1,25D3 increased poly(I:C)-induced IL-8 mRNA and protein expression after 2 to 6 hours. However, when cells were pretreated with 1,25D3 for 24 hours, 1,25D3 decreased cytokine expression. For microarray analysis, 308 genes were differentially expressed by 1,25D3 treatment in hTCEpi, and 69 genes in SV40s. Quantitative (q)PCR confirmed the vitamin D-mediated upregulation of target genes, including nuclear factor of κ light polypeptide gene enhancer in B-cells inhibitor, α (IκBα). In addition to increased transcript levels, IκBα protein was increased by 28% following 24 hours of vitamin D treatment.
  
  
  
  Microarray analysis demonstrates that vitamin D regulates numerous genes in HCEC and influences TLR signaling through upregulation of IκBα. 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.
authors.affiliation: College of Optometry University of Houston, Houston, Texas, United States.
authors.forename: Rose Y
authors.initials: RY
authors.lastname: Reins
authors.affiliation: Department of Biology and Biochemistry, Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, Texas, United States.
authors.forename: Fahmi
authors.initials: F
authors.lastname: Mesmar
authors.affiliation: Department of Biology and Biochemistry, Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, Texas, United States 3Science for Life Laboratory, School of Biotechnology, KTH Royal Institute of Technology, Solna, Sweden 4Departme.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Williams
authors.affiliation: College of Optometry University of Houston, Houston, Texas, United States.
authors.forename: Alison M
authors.initials: AM
authors.lastname: McDermott
mesh_terms: D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D019573:Epithelium, Corneal / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics*; D007634:Keratitis / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D018167:Receptors, Calcitriol / Q000378:metabolism; D015398:Signal Transduction; D046888:Tissue Array Analysis; D014158:Transcription, Genetic; D014807:Vitamin D / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology
chemical_list: D016209:Interleukin-8; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D014815:Vitamins; D014807:Vitamin D