title: Exposure of a corneal epithelial cell line (hTCEpi) to Demodex-associated Bacillus proteins results in an inflammatory response.
abstract: OBJECTIVE
  A role for a bacterium, Bacillus oleronius, originally isolated from a Demodex mite, in the induction of ocular rosacea has been proposed. The aim of this work was to characterize the response of a corneal epithelial cell line to Bacillus proteins, as this might give an insight into how such proteins contribute to the symptoms of ocular rosacea in vivo.
  
  
  METHODS
  The effect of exposing Bacillus protein preparation on human telomerase-immortalized corneal epithelial cells (hTCEpi) was measured by monitoring changes in cell proliferation and the expression of a number of genes associated with inflammation. The production of inflammatory cytokines was measured and the expression and activity of MMP-9 was quantified.
  
  
  RESULTS
  Exposure of hTCEpi cells to 2 or 6 μg/mL Bacillus protein resulted in a dose-dependent reduction in cell proliferation. Exposure of cells to 6 μg/mL Bacillus protein did not induce apoptosis, but there was an increase in the expression of genes coding for IL-6 (13.8-fold), IL-1β (4.0-fold), IL-8 (11.1-fold), and TNF-α (4.1-fold). Increased expression of genes coding for the defensins, CCL20 (4.5-fold) and S100A7 (6.8-fold) also was observed. Elevated production of IL-6 and IL-8 was evident from cells exposed to 2 and 6 μg/mL Bacillus protein. The hTCEpi cells demonstrated increased MMP-9 expression (3.2-fold, P = 0.003) and activity (2.2-fold, P = 0.0186) after 48 hours of exposure to 6 μg/mL Bacillus protein preparation.
  
  
  CONCLUSIONS
  The results suggest that interaction of Demodex-associated Bacillus proteins with the corneal surface could lead to tissue degradation and inflammation, possibly leading to corneal scarring.
authors.affiliation: Department of Biology, National University of Ireland Maynooth, County Kildare, Ireland.
authors.forename: Frederick W
authors.initials: FW
authors.lastname: McMahon
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.
authors.forename: Clair
authors.initials: C
authors.lastname: Gallagher
authors.affiliation: Department of Biology, National University of Ireland Maynooth, County Kildare, Ireland.
authors.forename: Niamh
authors.initials: N
authors.lastname: O'Reilly
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.
authors.forename: Martin
authors.initials: M
authors.lastname: Clynes
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.
authors.forename: Finbarr
authors.initials: F
authors.lastname: O'Sullivan
authors.affiliation: Department of Biology, National University of Ireland Maynooth, County Kildare, Ireland.
authors.forename: Kevin
authors.initials: K
authors.lastname: Kavanagh
mesh_terms: D001407:Bacillus / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D002453:Cell Cycle; D002460:Cell Line; D049109:Cell Proliferation; D003320:Corneal Ulcer / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D019573:Epithelium, Corneal / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D015818:Eye Infections, Bacterial / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D006801:Humans
chemical_list: D001426:Bacterial Proteins
keywords: Bacillus; Demodex; corneal scarring; corneal surface; ocular rosacea; sterile ulcers