The mouse autonomic nervous system modulates inflammation and epithelial renewal after corneal abrasion through the activation of distinct local macrophages.

Inflammation and reepithelialization after corneal abrasion are critical for the rapid restoration of vision and the prevention of microbial infections. However, the endogenous regulatory mechanisms are not completely understood. Here we report that the manipulation of autonomic nervous system (ANS) regulates the inflammation and healing processes. The activation of sympathetic nerves inhibited reepithelialization after corneal abrasion but increased the influx of neutrophils and the release of inflammatory cytokines. Conversely, the activation of parasympathetic nerves promoted reepithelialization and inhibited the influx of neutrophils and the release of inflammatory cytokines. Furthermore, we observed that CD64+CCR2+ macrophages in the cornea preferentially expressed the ß-2 adrenergic receptor (AR), whereas CD64+CCR2- macrophages preferentially expressed the α-7 nicotinic acetylcholine receptor (α7nAChR). After abrasion, the topical administration of a ß2AR agonist further enhanced the expression of the proinflammatory genes in the CD64+CCR2+ cell subset sorted from injured corneas. In contrast, the topical administration of an α7nAChR agonist further enhanced the expression of the anti-inflammatory genes in the CD64+CCR2- subset. Thus crosstalk between the ANS and local macrophage populations is necessary for the progress of corneal wound repair. Manipulation of ANS inputs to the wounded cornea may represent an alternative approach to the treatment of impaired wound healing.

Mast Cells Participate in Corneal Development in Mice.

The development of the cornea, a highly specialized transparent tissue located at the anterior of the eye, is coordinated by a variety of molecules and cells. Here, we report that mast cells (MCs), recently found to be involved in morphogenesis, played a potentially important role in corneal development in mice. We show that two different waves of MC migration occurred during corneal development. In the first wave, MCs migrated to the corneal stroma and became distributed throughout the cornea. This wave occurred by embryonic day 12.5, with MCs disappearing from the cornea at the time of eyelid opening. In the second wave, MCs migrated to the corneal limbus and became distributed around limbal blood vessels. The number of MCs in this region gradually increased after birth and peaked at the time of eyelid opening in mice, remaining stable after postnatal day 21. We also show that integrin α4ß7 and CXCR2 were important for the migration of MC precursors to the corneal limbus and that c-Kit-dependent MCs appeared to be involved in the formation of limbal blood vessels and corneal nerve fibers. These data clearly revealed that MCs participate in the development of the murine cornea.

Changes in mouse corneal epithelial innervation with age.

PURPOSE: We defined the quantitative changes in corneal epithelial nerve fibers during mouse development. METHODS: Corneal whole mounts from 36 mice were immunostained with a specific anti-ß-III tubulin antibody to label nerve fibers. Epithelial nerve fibers in the whole cornea were scanned and imaged using deconvolution microscopy. Subbasal nerve fiber and nerve terminal densities were calculated based on the length of nerve fibers located in each 1 mm² area of the corneal surface. RESULTS: The epithelial nerve terminals and corneal surface areas increased at different rates; therefore, the variations in corneal epithelial nerve terminal density and number were asynchronous. The maximum epithelial nerve terminal density was reached at postnatal day 24, which remained constant until postnatal month 2 and then decreased significantly. However, the epithelial nerve terminal number increased significantly until postnatal month 2 and then subsequently decreased significantly. In contrast to the epithelial nerve terminal, the subbasal nerve fiber density and number increased significantly until postnatal month 2 and then decreased. Since the subbasal nerve vortex was formed at postnatal day 24, its location, morphological appearance, and directionality did not display any further changes with age. CONCLUSIONS: The changes in the corneal epithelial nerve fibers can be divided into two stages after birth (day 1 to 2 months and 2-15 months). During the first stage, the corneal epithelial nerve fiber density increased significantly with increasing corneal surface area. During the second stage, the density presented a significant downward trend.