Neurturin-deficient mice develop dry eye and keratoconjunctivitis sicca

Invest Ophthalmol Vis Sci. 2003 Oct;44(10):4223-9. doi: 10.1167/iovs.02-1319.

Abstract

Purpose: Neurturin has been identified as a neurotrophic factor for parasympathetic neurons. Neurturin-deficient (NRTN(-/-)) mice have defective parasympathetic innervation of their lacrimal glands. This study was conducted to evaluate tear function and ocular surface phenotype in NRTN(-/-) mice.

Methods: Determined by tail genomic DNA PCR, 25 NRTN(-/-) mice and 17 neurturin-normal (NRTN(+/+)) mice aged 6 weeks to 4 months were evaluated. Aqueous tear production, tear fluorescein clearance and corneal sensation were serially measured. Corneal permeability to AlexaFluor dextran (AFD; Molecular Probes, Eugene, OR) was measured by a fluorometric assay at 485 nm excitation and 530 nm emission. Histology was evaluated in PAS-stained sections. Mucin and HLA class II (IA) antigen were assessed by immunofluorescent staining. Tear IL-1beta was measured by ELISA, and tear matrix metalloproteinase (MMP)-9 by zymography. Gene expression in the corneal epithelia was analyzed by semiquantitative RT-PCR.

Results: In comparison to that in age-matched NRTN(+/+) mice, aqueous tear production, tear fluorescein clearance, and corneal sensation were significantly reduced in NRTN(-/-) mice, whereas corneal permeability to AFD was significantly increased. Immunoreactive MUC-4 and -5AC mucin and goblet cell density (P < 0.001) in the conjunctiva of NRTN(-/-) mice were lower than in NRTN(+/+) mice. The expression of MUC-1 and -4 mRNA by the corneal epithelium was reduced in NRTN(-/-) mice. There were a significantly greater number of IA antigen-positive conjunctival epithelial cells in NRTN(-/-) mice than NRTN(+/+) mice. Tear fluid IL-1beta and MMP-9 concentrations and the expression of IL-1beta, TNF-alpha, macrophage inflammatory protein (MIP)-2, cytokine-induced neutrophil chemoattractant (KC), and MMP-9 mRNA by the corneal epithelia were significantly increased in NRTN(-/-) mice, compared with NRTN(+/+) mice.

Conclusions: Neurturin-deficient mice show phenotypic changes and ocular surface inflammation that mimic human keratoconjunctivitis sicca. This model supports the importance of a functional ocular surface-central nervous system-lacrimal gland sensory-autonomic neural network in maintaining ocular surface health and homeostasis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Count
  • Cornea / metabolism
  • Disease Models, Animal
  • Enzyme-Linked Immunosorbent Assay
  • Fluorescein / metabolism
  • Fluorescent Antibody Technique, Indirect
  • Fluorophotometry
  • Goblet Cells / cytology
  • Histocompatibility Antigens Class II / metabolism
  • Interleukin-1 / metabolism
  • Keratoconjunctivitis / etiology*
  • Keratoconjunctivitis / metabolism*
  • Keratoconjunctivitis / pathology
  • Lacrimal Apparatus / metabolism*
  • Matrix Metalloproteinase 9 / metabolism
  • Mice
  • Mice, Knockout
  • Mucins / genetics
  • Mucins / metabolism
  • Nerve Growth Factors / deficiency*
  • Nerve Growth Factors / genetics
  • Neurturin
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tears / metabolism*

Substances

  • Histocompatibility Antigens Class II
  • Interleukin-1
  • Mucins
  • Nerve Growth Factors
  • Neurturin
  • Nrtn protein, mouse
  • Matrix Metalloproteinase 9
  • Fluorescein