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Yu R, Liu S, Li Y, Lu L, Huang S, Chen X, Xue Y, Fu T, Liu J, Li Z. TRPV1 + sensory nerves suppress conjunctival inflammation via SST-SSTR5 signaling in murine allergic conjunctivitis. Mucosal Immunol 2024; 17:211-225. [PMID: 38331094 DOI: 10.1016/j.mucimm.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 02/10/2024]
Abstract
Allergic conjunctivitis (AC), an allergen-induced ocular inflammatory disease, primarily involves mast cells (MCs) and eosinophils. The role of neuroimmune mechanisms in AC, however, remains to be elucidated. We investigated the effects of transient receptor potential vanilloid 1 (TRPV1)-positive sensory nerve ablation (using resiniferatoxin) and TRPV1 blockade (using Acetamide, N-[4-[[6-[4-(trifluoromethyl)phenyl]-4-pyrimidinyl]oxy]-2-benzothiazolyl] (AMG-517)) on ovalbumin-induced conjunctival allergic inflammation in mice. The results showed an exacerbation of allergic inflammation as evidenced by increased inflammatory gene expression, MC degranulation, tumor necrosis factor-α production by MCs, eosinophil infiltration and activation, and C-C motif chemokine 11 (CCL11) (eotaxin-1) expression in fibroblasts. Subsequent findings demonstrated that TRPV1+ sensory nerves secrete somatostatin (SST), which binds to SST receptor 5 (SSTR5) on MCs and conjunctival fibroblasts. SST effectively inhibited tumor necrosis factor-α production in MCs and CCL11 expression in fibroblasts, thereby reducing eosinophil infiltration and alleviating AC symptoms, including eyelid swelling, lacrimation, conjunctival chemosis, and redness. These findings suggest that targeting TRPV1+ sensory nerve-mediated SST-SSTR5 signaling could be a promising therapeutic strategy for AC, offering insights into neuroimmune mechanisms and potential targeted treatments.
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Affiliation(s)
- Ruoxun Yu
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Sijing Liu
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Yan Li
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Liyuan Lu
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Shuoya Huang
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Xinwei Chen
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Yunxia Xue
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China
| | - Ting Fu
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China
| | - Jun Liu
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China.
| | - Zhijie Li
- International Ocular Surface Research Center, Institute of Ophthalmology, and Key Laboratory for Regenerative Medicine, Jinan University, Guangzhou, China; Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, China.
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Lucius A, Chhatwal S, Valtink M, Reinach PS, Li A, Pleyer U, Mergler S. L-Carnitine Suppresses Transient Receptor Potential Vanilloid Type 1 Activation in Human Corneal Epithelial Cells. Int J Mol Sci 2023; 24:11815. [PMID: 37511574 PMCID: PMC10380586 DOI: 10.3390/ijms241411815] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Tear film hyperosmolarity induces dry eye syndrome (DES) through transient receptor potential vanilloid type 1 (TRPV1) activation. L-carnitine is a viable therapeutic agent since it protects against this hypertonicity-induced response. Here, we investigated whether L-carnitine inhibits TRPV1 activation by blocking heat- or capsaicin-induced increases in Ca2+ influx or hyperosmotic stress-induced cell volume shrinkage in a human corneal epithelial cell line (HCE-T). Single-cell fluorescence imaging of calcein/AM-loaded cells or fura-2/AM-labeled cells was used to evaluate cell volume changes and intracellular calcium levels, respectively. Planar patch-clamp technique was used to measure whole-cell currents. TRPV1 activation via either capsaicin (20 µmol/L), hyperosmolarity (≈450 mosmol/L) or an increase in ambient bath temperature to 43 °C induced intracellular calcium transients and augmented whole-cell currents, whereas hypertonicity induced cell volume shrinkage. In contrast, either capsazepine (10 µmol/L) or L-carnitine (1-3 mmol/L) reduced all these responses. Taken together, L-carnitine and capsazepine suppress hypertonicity-induced TRPV1 activation by blocking cell volume shrinkage.
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Affiliation(s)
- Alexander Lucius
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Sirjan Chhatwal
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Monika Valtink
- Faculty of Medicine, Institute of Anatomy, TU Dresden, 01216 Dresden, Germany
- Equality and Diversity Unit, Faculty of Medicine, TU Dresden, 01307 Dresden, Germany
| | - Peter S Reinach
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 325027, China
| | - Aruna Li
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Uwe Pleyer
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
| | - Stefan Mergler
- Klinik für Augenheilkunde, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany
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Rigas Y, Treat BR, Shane J, Shanks RMQ, St. Leger AJ. Genetic Manipulation of Corynebacterium mastitidis to Better Understand the Ocular Microbiome. Invest Ophthalmol Vis Sci 2023; 64:19. [PMID: 36799874 PMCID: PMC9942783 DOI: 10.1167/iovs.64.2.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 01/24/2023] [Indexed: 02/18/2023] Open
Abstract
Purpose Corynebacterium spp. are Gram-positive bacteria commonly associated with the ocular surface. Corynebacterium mastitidis was isolated from mouse eyes and was demonstrated to induce a beneficial immune response that can protect the eye from pathogenic infection. Because eye-relevant Corynebacterium spp. are not well described, we generated a C. mast transposon (Tn) mutant library to gain a better understanding of the nature of eye-colonizing bacteria. Methods Tn mutagenesis was performed with a custom Tn5-based transposon that incorporated a promoterless gene for the fluorescent protein mCherry. We screened our library using flow cytometry and enzymatic assays to identify useful mutants that demonstrate the utility of our approach. Results Fluorescence-activated cell sorting (FACS) of mCherry+ bacteria allowed us to identify a highly fluorescent mutant that was detectable on the murine ocular surface using microscopy. We also identified a functional knockout that was unable to hydrolyze urea, UreaseKO. Although uric acid is an antimicrobial factor produced in tears, UreaseKO bacterium maintained an ability to colonize the eye, suggesting that urea hydrolysis is not required for colonization. In vitro and in vivo, both mutants maintained the potential to stimulate protective immunity as compared to wild-type C. mast. Conclusions In sum, we describe a method to genetically modify an eye-colonizing microbe, C. mast. Furthermore, the procedures outlined here will allow for the continued development of genetic tools for modifying ocular Corynebacterium spp., which will lead to a more complete understanding of the interactions between the microbiome and host immunity at the ocular surface.
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Affiliation(s)
- Yannis Rigas
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Benjamin R. Treat
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Jackie Shane
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Robert M. Q. Shanks
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
| | - Anthony J. St. Leger
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
- Department of Immunology, University of Pittsburgh, Pittsburgh Pennsylvania, United States
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Neuroimmune crosstalk in the cornea: The role of immune cells in corneal nerve maintenance during homeostasis and inflammation. Prog Retin Eye Res 2022; 91:101105. [PMID: 35868985 DOI: 10.1016/j.preteyeres.2022.101105] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 07/01/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022]
Abstract
In the cornea, resident immune cells are in close proximity to sensory nerves, consistent with their important roles in the maintenance of nerves in both homeostasis and inflammation. Using in vivo confocal microscopy in humans, and ex vivo immunostaining and fluorescent reporter mice to visualize corneal sensory nerves and immune cells, remarkable progress has been made to advance our understanding of the physical and functional interactions between corneal nerves and immune cells. In this review, we summarize and discuss recent studies relating to corneal immune cells and sensory nerves, and their interactions in health and disease. In particular, we consider how disrupted corneal nerve axons can induce immune cell activity, including in dendritic cells, macrophages and other infiltrating cells, directly and/or indirectly by releasing neuropeptides such as substance P and calcitonin gene-related peptide. We summarize growing evidence that the role of corneal intraepithelial immune cells is likely different in corneal wound healing versus other inflammatory-dominated conditions. The role of different types of macrophages is also discussed, including how stromal macrophages with anti-inflammatory phenotypes communicate with corneal nerves to provide neuroprotection, while macrophages with pro-inflammatory phenotypes, along with other infiltrating cells including neutrophils and CD4+ T cells, can be inhibitory to corneal re-innervation. Finally, this review considers the bidirectional interactions between corneal immune cells and corneal nerves, and how leveraging this interaction could represent a potential therapeutic approach for corneal neuropathy.
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Mucosal immunology of the ocular surface. Mucosal Immunol 2022; 15:1143-1157. [PMID: 36002743 PMCID: PMC9400566 DOI: 10.1038/s41385-022-00551-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/26/2022] [Accepted: 06/10/2022] [Indexed: 02/04/2023]
Abstract
The eye is a sensory organ exposed to the environment and protected by a mucosal tissue barrier. While it shares a number of features with other mucosal tissues, the ocular mucosal system, composed of the conjunctiva, Meibomian glands, and lacrimal glands, is specialized to address the unique needs of (a) lubrication and (b) host defense of the ocular surface. Not surprisingly, most challenges, physical and immunological, to the homeostasis of the eye fall into those two categories. Dry eye, a dysfunction of the lacrimal glands and/or Meibomian glands, which can both cause, or arise from, sensory defects, including those caused by corneal herpes virus infection, serve as examples of these perturbations and will be discussed ahead. To preserve vision, dense neuronal and immune networks sense various stimuli and orchestrate responses, which must be tightly controlled to provide protection, while simultaneously minimizing collateral damage. All this happens against the backdrop of, and can be modified by, the microorganisms that colonize the ocular mucosa long term, or that are simply transient passengers introduced from the environment. This review will attempt to synthesize the existing knowledge and develop trends in the study of the unique mucosal and immune elements of the ocular surface.
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