This laboratory's long-term goal is to research the molecular and cellular biology of corneal wound healing. During the current grant period, studies from the lab have significantly improved our understanding of the pathogenesis of diabetic neurotrophic keratopathy (DNK), a major cause of the morbidity of the cornea. We demonstrated that cells in the corneal epithelium communicate through the release of soluble factors, such as TGF?3, IL-1RA, Sema3C (epithelial cells), CNTF (dendritic cells, DC), and VIP (neuron), in response to wounding. Diabetes mellitus disrupts cell-cell interaction, resulting in DNK. Recently, extracellular vesicles, particularly exosomes, were discovered as an additional mechanism for intercellular communication. Exosomes are secreted by most cell types and encapsulate a selective set of proteins, genetic material (for example, mRNAs, miRNAs, lncRNAs, DNA), metabolites, and lipids, and horizontally transfer their cargo to recipient cells. Moreover, these natural nanosized membrane vesicles are excellent delivery vehicles for drugs and therapeutics. We discovered that both cultured mouse corneal epithelial cells (CECs) and bone marrow-derived dendritic cells (BMDCs) release exosomes, which can be readily purified and taken up by each other and by sensory nerves in vitro and/or in vivo. Additionally, we found that the miRNA and protein contents of exosomes vary depending on patho/physiology; that exosomes derived from healing, but not from quiescent CECs, accelerate attenuated wound healing in diabetic mouse corneas; and that exosomes isolated from BMDCs can functionally replace the role of DCs in supporting corneal wound closure. Our published and preliminary studies led to the hypothesis that exosomes communicate critical signaling events in the cornea during wound healing and may be modified to boost therapeutic potential for treating DNK. This application includes three Aims.
Aim 1 : To explore the molecular mechanism by which CEC exosomes (which have been isolated from quiescent and healing CECs and cultured in normal and high glucose) are therapeutically effective or pathogenic for DNK.
Aim 2 : To investigate the role of BMDC exosomes (which have been isolated from bone marrow derived DCs) purified from normal and diabetic type 1 and 2 diabetic mice in mediating corneal wound healing and macrophage activation.
Aim 3 : To determine whether modifying Exo contents can ameliorate DNK as well as impaired skin wound healing in type 1 and 2 mice. Completion of the proposed study will demonstrate exosomes are a significant mediator of cell function or dysfunction depending on the nature of exosomes, identify encapsulated molecules such as proteins and specific microRNAs responsible for exosome regenerative power, and modify purified exosomes to boost their therapeutic potential for treating DNK where there is an unmet clinical need.

Public Health Relevance

This proposal is to determine the role of exosomes secreted by corneal epithelial cells and dendritic cells in mediating epithelial wound healing and sensory nerve regeneration as well as their defects in diabetic corneas. The knowledge gained will be critical for understanding the biology of this novel type of cell-cell communication in the cornea and for the goal of developing mechanism-based, efficacious therapeutic modalities for treating diabetic neurotrophic keratopathy/peripheral neuropathy.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Mckie, George Ann
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Wayne State University
Schools of Medicine
United States
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Han, Jing; Li, Yue; Liu, Xiuli et al. (2018) Metformin suppresses retinal angiogenesis and inflammation in vitro and in vivo. PLoS One 13:e0193031
Cui, Xinhan; Gao, Nan; Me, Rao et al. (2018) TSLP Protects Corneas From Pseudomonas aeruginosa Infection by Regulating Dendritic Cells and IL-23-IL-17 Pathway. Invest Ophthalmol Vis Sci 59:4228-4237
Sun, Haijing; Lee, Patrick; Yan, Chenxi et al. (2018) Inhibition of Soluble Epoxide Hydrolase 2 Ameliorates Diabetic Keratopathy and Impaired Wound Healing in Mouse Corneas. Diabetes 67:1162-1172
Gao, Nan; Me, Rao; Dai, Chenyang et al. (2018) Opposing Effects of IL-1Ra and IL-36Ra on Innate Immune Response to Pseudomonas aeruginosa Infection in C57BL/6 Mouse Corneas. J Immunol 201:688-699
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Zhang, Xilin; Liu, Queping; Wang, Jie et al. (2016) TIM-4 is differentially expressed in the distinct subsets of dendritic cells in skin and skin-draining lymph nodes and controls skin Langerhans cell homeostasis. Oncotarget 7:37498-37512
Yan, Chenxi; Gao, Nan; Sun, Haijing et al. (2016) Targeting Imbalance between IL-1? and IL-1 Receptor Antagonist Ameliorates Delayed Epithelium Wound Healing in Diabetic Mouse Corneas. Am J Pathol 186:1466-80
Gao, Nan; Yan, Chenxi; Lee, Patrick et al. (2016) Dendritic cell dysfunction and diabetic sensory neuropathy in the cornea. J Clin Invest 126:1998-2011

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