Impact of Obesity and Age on Mouse Corneal Innervation at the Epithelial-Stromal Interface

Authors

Justin A Courson
Rolando E Rumbaut
Alan R Burns

Publication Date

5-1-2024

Journal

Investigative Ophthalmology & Visual Science

DOI

10.1167/iovs.65.5.11

PMID

38709524

PMCID

PMC11078165

PubMedCentral® Posted Date

5-6-2024

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Animals, Obesity, Mice, Mice, Inbred C57BL, Epithelium, Corneal, Corneal Stroma, Microscopy, Electron, Scanning, Aging, Male, Disease Models, Animal, Cornea, Diet, High-Fat, obesity, aging, corneal nerves, electron microscopy, serial block-face

Abstract

PURPOSE: The corneal epithelium is the most highly innervated structure in the body. Previously, we reported a novel event whereby stromal axons fuse with basal epithelial cells, limiting nerve penetration into the epithelium. Although corneal-epithelial nerves undergo changes in sensitivity and distribution throughout life and in response to an obesogenic diet, it is unknown if neuronal-epithelial cell fusion is altered. Here, we sought to determine if neuronal-epithelial cell fusion frequency correlates with obesogenic diet consumption and age.

METHODS: Corneas were collected from C57BL/6 mice and evaluated for neuronal-epithelial cell fusion frequency using serial block-face scanning electron microscopy. To assess the correlation between diet-induced obesity and fusion frequency, 6-week-old mice were fed either a normal diet or an obesogenic diet for 10 weeks. To assess changes in fusion frequency between young and adult mice under normal dietary conditions, 9- and 24-week-old mice were used.

RESULTS: Mice fed a 10-week obesogenic diet showed 87% of central-cornea stromal nerves engaged in fusion compared with only 54% in age-matched controls (16 weeks old). In 9-week-old normal-diet animals, 48% of central-cornea stromal nerves contained fusing axons and increased to 81% at 24 weeks of age. Corneal sensitivity loss correlated with increased body weight and adiposity regardless of age and diet.

CONCLUSIONS: Neuronal-epithelial cell fusion positively correlates with age and obesogenic diet consumption, and corneal nerve sensitivity loss correlates with increased body weight and adiposity, regardless of age and diet. As such, neuronal-epithelial cell fusion may play a role in corneal nerve density and sensitivity regulation.