Interferon-γ exacerbates dry eye-induced apoptosis in conjunctiva through dual apoptotic pathways

Invest Ophthalmol Vis Sci. 2011 Aug 9;52(9):6279-85. doi: 10.1167/iovs.10-7081.

Abstract

Purpose: To investigate the role of interferon (IFN)-γ in dry eye-associated conjunctival apoptosis.

Methods: Desiccating stress (DS) was created in C57BL/6 (B6) and C57BL/6 IFN-γ-knockout (B6γKO) mice. A separate group of mice of both strains also received subconjunctival injections of exogenous IFN-γ or vehicle control (BSA) at days 0, +2, and +4 after DS. Immunoreactivity to active (Ac)-caspase-3, -8, and -9 and terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) were evaluated in cryosections. Goblet cell apoptosis was assessed by MUC5AC and TUNEL double staining. Levels of caspase-3, -8, -9, Fas, and Fas-associated protein with Death Domain (FADD) mRNA in conjunctiva were measured by real-time PCR. The activity of caspase-3, -8, or -9 was measured using fluorometric assay.

Results: Increased Ac-caspase-3 and -8 and TUNEL immunoreactivity were noted in conjunctival epithelia in B6 mice compared with B6γKO mice after DS, and exogenous IFN-γ administration further increased these parameters. DS-induced conjunctival apoptosis was greatest in the goblet cell area and was accompanied by a decrease in MUC5AC expression in the B6 and B6-IFN-γ-injected groups compared with the B6γKO and B6-BSA-injected groups. B6γKO mice were resistant to DS-induced apoptosis; however, B6γKO receiving IFN-γ yielded results similar to those for B6 wild-type. Caspase-9 production and activity were not increased with DS in B6 or B6γKO mice; however, the administration of IFN-γ significantly increased caspase-9 production and activity in both strains compared with vehicle-injected mice.

Conclusions: IFN-γ plays a pivotal role in exacerbating conjunctival apoptosis through dual apoptotic pathways with DS.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Carrier Proteins / genetics
  • Caspases / genetics
  • Caspases / metabolism
  • Co-Repressor Proteins
  • Conjunctiva / metabolism
  • Conjunctiva / pathology*
  • Disease Models, Animal
  • Dry Eye Syndromes / genetics
  • Dry Eye Syndromes / metabolism
  • Dry Eye Syndromes / pathology*
  • Female
  • Goblet Cells / metabolism
  • Goblet Cells / pathology
  • In Situ Nick-End Labeling
  • Interferon-gamma / pharmacology*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Molecular Chaperones
  • Mucin 5AC / genetics
  • Nuclear Proteins / genetics
  • RNA, Messenger / metabolism
  • Receptors, Interferon / metabolism
  • Recombinant Proteins
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spectrometry, Fluorescence
  • Stress, Physiological
  • fas Receptor / genetics

Substances

  • Carrier Proteins
  • Co-Repressor Proteins
  • Daxx protein, mouse
  • Intracellular Signaling Peptides and Proteins
  • Molecular Chaperones
  • Muc5ac protein, mouse
  • Mucin 5AC
  • Nuclear Proteins
  • RNA, Messenger
  • Receptors, Interferon
  • Recombinant Proteins
  • fas Receptor
  • interferon gamma receptor
  • Interferon-gamma
  • Caspases