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

Abstract

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 CD64CCR2 macrophages in the cornea preferentially expressed the β-2 adrenergic receptor (AR), whereas CD64CCR2 macrophages preferentially expressed the α-7 nicotinic acetylcholine receptor (α7nAChR). After abrasion, the topical administration of a β2AR agonist further enhanced the expression of the proinflammatory genes in the CD64CCR2 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 CD64CCR2 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.

Morphological and Functional Changes of Corneal Nerves and Their Contribution to Peripheral and Central Sensory Abnormalities

“…Autonomic nervous fibers of sympathetic (upper cervical ganglion) and parasympathetic system (ciliary ganglion) participate in the regulation of corneal wound healing and re-epithelialization (Jones and Marfurt, 1996;Xue et al, 2018;Xiao et al, 2019). Theses biological processes involve a number of concerted events including cell migration, proliferation, inflammation, and differentiation and extracellular matrix remodeling (Ljubimov and Saghizadeh, 2015).…”

“…Theses biological processes involve a number of concerted events including cell migration, proliferation, inflammation, and differentiation and extracellular matrix remodeling (Ljubimov and Saghizadeh, 2015). Interestingly, it was recently reported that the mouse autonomous system modulates inflammation and epithelial renewal after corneal abrasion through the activation of distinct local macrophages (Xue et al, 2018;Xiao et al, 2019).…”

Loss of Osteopontin Expression Reduces HSV-1-Induced Corneal Opacity

“…53,54 However, manipulating macrophage plasticity in the local environment through the addition of autonomic nervous system ligands during the course of inflammation is a promising development. 55 OPN is an extracellular matrix protein that greatly influences fibroblast proliferation, migration, and matrix remodeling and is a critical factor in corneal wound healing. 56 In terms of corneal HSV-1 infection and consistent with our data, a previous study reported that OPN-deficient mice presented with a significant drop in the incidence and severity of herpes stromal keratitis (HSK) following corneal infection out to day 15 pi.…”

“…53 , 54 However, manipulating macrophage plasticity in the local environment through the addition of autonomic nervous system ligands during the course of inflammation is a promising development. 55 …”

Resident Innate Immune Cells in the Cornea

“…These cells are mainly distributed throughout the cornea, including the center of the cornea and the corneal limbus (84). Through whole-mount immunostaining of the cornea and flow cytometric analysis, we identified the composition and distribution of macrophages in mice using the highly specific macrophage marker, CD64 (85), in the cornea ( Figure 3A) and categorized these cells into C-C chemokine receptor (CCR) type 2 − and CCR2 + populations (86)(87)(88)(89). Flow cytometric analysis of the corneal cells from the embryonic mice demonstrated that only CD64 + CCR2macrophages were present in the corneas of the E12.5 mice, and CD64 + CCR2 + macrophages were absent in the cornea until E17.5 ( Figure 3B) (86).…”