title: The Effect of Ambient Titanium Dioxide Microparticle Exposure to the Ocular Surface on the Expression of Inflammatory Cytokines in the Eye and Cervical Lymph Nodes.
abstract: To investigate the ocular immune response following exposure to airborne titanium dioxide (TiO2) microparticles.
  
  
  
  Rats in the TiO2-exposed group (n = 10) were exposed to TiO2 particles for 2 hours twice daily for 5 days, while the controls (n = 10) were not. Corneal staining score and tear lactic dehydrogenase (LDH) activity were measured to evaluate ocular surface damage, serum immunoglobulin (Ig) G and E were assayed by using enzyme-linked immunosorbent assay, and the size of cervical lymph nodes was measured. In addition, the expression of interleukin (IL)-4, IL-17, and interferon (IFN)-γ in the anterior segment of the eyeball and cervical lymph nodes was measured by immunohistochemistry, real-time reverse transcription-polymerase chain reaction (RT-PCR), and Western blot analysis.
  
  
  
  Median corneal staining score (3.0), tear LDH activity (0.24 optical density [OD]), and cervical lymph node size (36.9 mm2) were significantly higher in the TiO2-exposed group than in the control group (1.0, 0.13 OD, and 26.7 mm2, respectively). Serum IgG and IgE levels were found to be significantly elevated in the TiO2-exposed group (P = 0.021 and P = 0.021, respectively). Interleukin 4 expression was increased in the anterior segment of the eyeball and lymph nodes following TiO2 exposure, as measured by immunostaining, real-time RT-PCR, and Western blot. In addition, IL-17 and IFN-γ levels were also increased following TiO2 exposure compared to controls as measured by immunostaining.
  
  
  
  Exposure to airborne TiO2 induced ocular surface damage. The Type 2 helper T-cell pathway seems to play a dominant role in the ocular immune response following airborne TiO2 exposure.
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Youngsub
authors.initials: Y
authors.lastname: Eom
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Jong Suk
authors.initials: JS
authors.lastname: Song
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Hyun Kyu
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Boram
authors.initials: B
authors.lastname: Kang
authors.affiliation: Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Hyeon Chang
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Hyung Keun
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Hyo Myung
authors.initials: HM
authors.lastname: Kim
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005123:Eye / Q000187:drug effects / Q000378:metabolism*; D005128:Eye Diseases / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D007111:Immunity, Cellular; D008198:Lymph Nodes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008297:Male; D053758:Nanoparticles; D009333:Neck; D052638:Particulate Matter / Q000009:adverse effects*; D012313:RNA / Q000235:genetics; D051381:Rats; D011917:Rats, Inbred Lew; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013666:Tears / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology; D014025:Titanium / Q000009:adverse effects*
chemical_list: D016207:Cytokines; D052638:Particulate Matter; C009495:titanium dioxide; D012313:RNA; D014025:Titanium