Abstract: Axon regeneration capacity declines in mature retinal ganglion cells (RGCs). While a number of transcription factors and signaling molecules have been implicated to the loss of regenerative potential of RGC axon, their upstream regulators are unclear. We investigated the association between developmental decline of RGC regenerative potential and age-related changes in microRNA (miRNA) expression and showed that loss of axon regenerative potential can be partially restored by upregulating miR-19a in RGCs in vitro and in vivo. Regulating miRNA expression represents a new potential therapeutic approach to resuscitate age-related loss of axon growth ability.

Abstract: 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.