Oxidative stress induced inflammation initiates functional decline of tear production

PLoS One. 2012;7(10):e45805. doi: 10.1371/journal.pone.0045805. Epub 2012 Oct 5.

Abstract

Oxidative damage and inflammation are proposed to be involved in an age-related functional decline of exocrine glands. However, the molecular mechanism of how oxidative stress affects the secretory function of exocrine glands is unclear. We developed a novel mev-1 conditional transgenic mouse model (Tet-mev-1) using a modified tetracycline system (Tet-On/Off system). This mouse model demonstrated decreased tear production with morphological changes including leukocytic infiltration and fibrosis. We found that the mev-1 gene encodes Cyt-1, which is the cytochrome b(560) large subunit of succinate-ubiquinone oxidoreductase in complex II of mitochondria (homologous to succinate dehydrogenase C subunit (SDHC) in humans). The mev-1 gene induced excessive oxidative stress associated with ocular surface epithelial damage and a decrease in protein and aqueous secretory function. This new model provides evidence that mitochondrial oxidative damage in the lacrimal gland induces lacrimal dysfunction resulting in dry eye disease. Tear volume in Tet-mev-1 mice was lower than in wild type mice and histopathological analyses showed the hallmarks of lacrimal gland inflammation by intense mononuclear leukocytic infiltration and fibrosis in the lacrimal gland of Tet-mev-1 mice. These findings strongly suggest that oxidative stress can be a causative factor for the development of dry eye disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cytochrome b Group / genetics
  • Doxycycline
  • Dry Eye Syndromes / etiology*
  • Dry Eye Syndromes / physiopathology
  • Electron Transport Complex II / genetics
  • Inflammation / pathology*
  • Lacrimal Apparatus / pathology*
  • Male
  • Mice
  • Mice, Transgenic
  • Mitochondria / pathology
  • Oxidative Stress*

Substances

  • Cytochrome b Group
  • cytochrome b560
  • Electron Transport Complex II
  • Doxycycline

Grants and funding

This work was supported by Grant-in-Aid for Young Scientists (B) (22791692) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.