Macrophages are distributed throughout the body and are crucial for the restoration of damaged tissues. However, their characteristics in the cornea and roles in the repair of corneal injures are unclear. Here we show that corneal macrophages can be classified as CCR2− macrophages, which already exist in the cornea at embryonic day 12.5 (E12.5) and are similar to yolk sac-derived macrophages, microglia, in phenotype and gene expression, and CCR2+ macrophages, which do not appear in the cornea until E17.5. At a steady state, CCR2− corneal macrophages have local proliferation capacity and are rarely affected by monocytes; however, following corneal epithelial abrasion, most CCR2− corneal macrophages are replaced by monocytes. In contrast, CCR2+ macrophages are repopulated by monocytes under both a steady-state condition and following corneal wounding. Depletion of CCR2+ macrophages decreases corneal inflammation after epithelial abrasion, whereas depletion of CCR2− macrophages increases inflammation of the injured cornea. Loss of either cell type results in a delay in corneal healing. These data indicate that there are two unique macrophage populations present in the cornea, both of which participate in corneal wound healing by balancing the inflammatory response.

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.

No abstract

Circadian rhythms significantly influence corneal epithelium renewal and repair in mice. Our findings reveal possible opportunities for biological rhythm-based interventional strategies to control corneal healing and restore corneal homeostasis.

Corneal injuries and infections are the leading cause of blindness worldwide. Thus, understanding the mechanisms that control healing of the damaged cornea is critical for the development of new therapies to promptly restore vision. Innate lymphoid cells (ILCs) are a recently identified heterogeneous cell population that has been reported to orchestrate immunity and promote tissue repair in the lungs and skin after injury. However, whether ILCs can modulate the repair process in the cornea remains poorly understood. We identified a population of cornea-resident group 2 ILCs (ILC2s) in mice that express CD127, T1/ST2, CD90, and cKit. This cell population was relatively rare in corneas at a steady state but increased after corneal epithelial abrasion. Moreover, ILC2s were maintained and expanded locally at a steady state and after wounding. Depletion of this cell population caused a delay in corneal wound healing, whereas supplementation of ILC2s through adoptive transfer partially restored the healing process. Further investigation revealed that IL-25, IL-33, and thymic stromal lymphopoietin had critical roles in corneal ILC2 responses and that CCR2 corneal macrophages were an important producer of IL-33 in the cornea. Together, these results reveal the critical role of cornea-resident ILC2s in the restoration of corneal epithelial integrity after acute injury and suggest that ILC2 responses depend on local induction of IL-25, IL-33, and thymic stromal lymphopoietin.

Triptolide has been indicated potent anti-cancer effect involving multiple molecular targets and signaling pathways. High-mobility group box 1 (HMGB1) is a highly conserved DNA-binding protein taking part in breast cancer development. The therapeutic effect of triptolide on HMGB1 has not been reported. Thus, our study aims to clarify the role of HMGB1 in triptolide-induced anti-growth effect on breast cancer in vitro and in vivo. We demonstrated that triptolide significantly suppressed growth of breast cancer cells by inhibition of cell viability, clonogenic ability. Further studies evidenced that triptolide treatment not only inhibited HMGB1 mRNA expression, but also decreased supernatant level of HMGB1 in vitro. In line with these observations, exogenous recombinant HMGB1 (rHMGB1) promoted cell proliferation of breast cancer, and triptolide reversed the rHMGB1-promoted proliferative effect. As well, triptolide enhanced the antiproliferative activity of ethyl pyruvate (EP) (HMGB1 inhibitor). Furthermore, downstream correlation factors (Toll-like receptor 4 (TLR4) and phosphorylated-nuclear factor-kappaB (NF-κB) p65) of HMGB1 were significantly decreased in vitro after triptolide treatment. Consistantly, we confirmed that tumor growth was significantly inhibited after triptolide treatment in vivo. Meanwhile, immunohistochemical analyses showed that triptolide treatment significantly decreased the level of cytoplasmic HMGB1 and TLR4 expression, whereas the expression of NF-κB p65 was relatively higher in cytoplasm, and conversely lower in nucleus as compared to the control group. Collectively, these results demonstrate that triptolide suppresses the growth of breast cancer cells via reduction of HMGB1 expression in vitro and in vivo, which may provide new insights into the treament of breast cancer.

No abstract

Although antibiotics are useful, they can also bring negative effects. We found that antibiotic-treated mice exhibit an alteration in the gene expression profile of corneal tissues and a decrease in corneal nerve density. During corneal wound healing, antibiotic treatment was found to impair corneal nerve regeneration, an effect that could be largely reversed by reconstitution of the gut microbiota via fecal transplant. Furthermore, CCR2 − corneal macrophages were found to participate in the repair of damaged corneal nerves, and a decrease in CCR2 − corneal macrophages in antibiotic-treated mice, which could be reversed by fecal transplant, was observed. Adoptive transfer of CCR2 − corneal macrophages promoted corneal nerve regeneration in antibiotic-treated mice. The application of probiotics after administration of antibiotics also restored the proportion of CCR2 − corneal macrophages and increased the regeneration of corneal nerve fibers after epithelial abrasion. These results suggest that dysbiosis of the gut microbiota induced by antibiotic treatment impairs corneal nerve regeneration by affecting CCR2 − macrophage distribution in the cornea. This study also indicates the potential of probiotics as a therapeutic strategy for promoting the regeneration of damaged corneal nerve fibers when the gut microbiota is in dysbiosis.