title: Upregulated epidermal growth factor receptor expression following near-infrared irradiation simulating solar radiation in a three-dimensional reconstructed human corneal epithelial tissue culture model.
abstract: OBJECTIVE
  Humans are increasingly exposed to near-infrared (NIR) radiation from both natural (eg, solar) and artificial (eg, electrical appliances) sources. Although the biological effects of sun and ultraviolet (UV) exposure have been extensively investigated, the biological effect of NIR radiation is still unclear. We previously reported that NIR as well as UV induces photoaging and standard UV-blocking materials, such as sunglasses, do not sufficiently block NIR. The objective of this study was to investigate changes in gene expression in three-dimensional reconstructed corneal epithelial tissue culture exposed to broad-spectrum NIR irradiation to simulate solar NIR radiation that reaches human tissues.
  
  
  METHODS
  DNA microarray and quantitative real-time polymerase chain reaction analysis were used to assess gene expression levels in a three-dimensional reconstructed corneal epithelial model composed of normal human corneal epithelial cells exposed to water-filtered broad-spectrum NIR irradiation with a contact cooling (20°C). The water-filter allowed 1,000-1,800 nm wavelengths and excluded 1,400-1,500 nm wavelengths.
  
  
  RESULTS
  A DNA microarray with >62,000 different probes showed 25 and 150 genes that were up- or downregulated by at least fourfold and twofold, respectively, after NIR irradiation. In particular, epidermal growth factor receptor (EGFR) was upregulated by 19.4-fold relative to control cells. Quantitative real-time polymerase chain reaction analysis revealed that two variants of EGFR in human corneal epithelial tissue were also significantly upregulated after five rounds of 10 J/cm(2) irradiation (P<0.05).
  
  
  CONCLUSIONS
  We found that NIR irradiation induced the upregulated expression of EGFR in human corneal cells. Since over half of the solar energy reaching the Earth is in the NIR region, which cannot be adequately blocked by eyewear and thus can induce eye damage with intensive or long-term exposure, protection from both UV and NIR radiation may prevent changes in gene expression and in turn eye damage.
authors.affiliation: Department of Plastic Surgery, Clinica Tanaka Plastic, Reconstructive Surgery and Anti-aging Center; Department of Molecular Pathology, Shinshu University Graduate School of Medicine, Matsumoto, Nagano, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Department of Molecular Pathology, Shinshu University Graduate School of Medicine, Matsumoto, Nagano, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Nakayama
mesh_terms: D019573:Epithelium, Corneal / Q000528:radiation effects*; D066246:ErbB Receptors / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D007259:Infrared Rays / Q000009:adverse effects*; D020411:Oligonucleotide Array Sequence Analysis; D000069079:Radiation Exposure / Q000009:adverse effects*; D013472:Sunlight / Q000009:adverse effects*; D046509:Tissue Culture Techniques; D015854:Up-Regulation
chemical_list: C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: DNA microarray; eye damage; gene expression; quantitative real-time PCR analysis; solar near-infrared