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Pitha I, Du L, Nguyen TD, Quigley H. IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors. Prog Retin Eye Res 2024; 99:101232. [PMID: 38110030 PMCID: PMC10960268 DOI: 10.1016/j.preteyeres.2023.101232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 12/10/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.
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Affiliation(s)
- Ian Pitha
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Center for Nanomedicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liya Du
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thao D Nguyen
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Harry Quigley
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Cao A, Gao W, Sawada T, Yoshimoto RU, Aijima R, Ohsaki Y, Kido MA. Transient Receptor Potential Channel Vanilloid 1 Contributes to Facial Mechanical Hypersensitivity in a Mouse Model of Atopic Asthma. J Transl Med 2023; 103:100149. [PMID: 37059266 DOI: 10.1016/j.labinv.2023.100149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/22/2023] [Accepted: 03/29/2023] [Indexed: 04/16/2023] Open
Abstract
Sensitive skin, a common pathophysiological feature of allergic diseases, is defined as an unpleasant sensation in response to stimuli that normally should not provoke such sensations. However, the relationship between allergic inflammation and hypersensitive skin in the trigeminal system remains to be elucidated. To explore whether bronchial allergic inflammation affects facial skin and primary sensory neurons, we used an ovalbumin (OVA)-induced asthma mouse model. Significant mechanical hypersensitivity was observed in the facial skin of mice with pulmonary inflammation induced by OVA sensitization compared to mice treated with adjuvant or vehicle as controls. The skin of OVA-treated mice showed an increased number of nerve fibers, especially rich intraepithelial nerves, compared to controls. Transient receptor potential channel vanilloid 1 (TRPV1)-immunoreactive nerves were enriched in the skin of OVA-treated mice. Moreover, epithelial TRPV1 expression was higher in OVA-treated mice than in controls. Trigeminal ganglia of OVA-treated mice displayed larger numbers of activated microglia/macrophages and satellite glia. In addition, more TRPV1 immunoreactive neurons were found in the trigeminal ganglia of OVA-treated mice than in controls. Mechanical hypersensitivity was suppressed in OVA-treated Trpv1-deficient mice, while topical skin application of a TRPV1 antagonist before behavioral testing reduced the reaction induced by mechanical stimulation. Our findings reveal that mice with allergic inflammation of the bronchi had mechanical hypersensitivity in the facial skin that may have resulted from TRPV1-mediated neuronal plasticity and glial activation in the trigeminal ganglion.
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Affiliation(s)
- Ailin Cao
- Division of Histology and Neuroanatomy, Department of Anatomy and Physiology, Faculty of Medicine, Saga University, Saga, Japan; Department of Oral Pathology, Graduate School of Dental Science, Kyushu University, Fukuoka, Japan
| | - Weiqi Gao
- Division of Histology and Neuroanatomy, Department of Anatomy and Physiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Takeshi Sawada
- Division of Histology and Neuroanatomy, Department of Anatomy and Physiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Reiko U Yoshimoto
- Division of Histology and Neuroanatomy, Department of Anatomy and Physiology, Faculty of Medicine, Saga University, Saga, Japan; Department of Oral Pathology, Graduate School of Dental Science, Kyushu University, Fukuoka, Japan
| | - Reona Aijima
- Department of Oral Maxillofacial Surgery, Faculty of Medicine, Saga University, Saga, Japan
| | - Yasuyoshi Ohsaki
- Division of Histology and Neuroanatomy, Department of Anatomy and Physiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Mizuho A Kido
- Division of Histology and Neuroanatomy, Department of Anatomy and Physiology, Faculty of Medicine, Saga University, Saga, Japan; Department of Oral Pathology, Graduate School of Dental Science, Kyushu University, Fukuoka, Japan.
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Mu K, Yu S, Kitts DD. The Role of Nitric Oxide in Regulating Intestinal Redox Status and Intestinal Epithelial Cell Functionality. Int J Mol Sci 2019; 20:E1755. [PMID: 30970667 PMCID: PMC6479862 DOI: 10.3390/ijms20071755] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 03/29/2019] [Accepted: 04/03/2019] [Indexed: 12/11/2022] Open
Abstract
Important functions of intestinal epithelial cells (IECs) include enabling nutrient absorption to occur passively and acting as a defense barrier against potential xenobiotic components and pathogens. A compromise to IEC function can result in the translocation of bacteria, toxins, and allergens that lead to the onset of disease. Thus, the maintenance and optimal function of IECs are critically important to ensure health. Endogenous biosynthesis of nitric oxide (NO) regulates IEC functionality both directly, through free radical activity, and indirectly through cell signaling mechanisms that impact tight junction protein expression. In this paper, we review the current knowledge on factors that regulate inducible nitric oxide synthase (iNOS) and the subsequent roles that NO has on maintaining IECs' intestinal epithelial barrier structure, functions, and associated mechanisms of action. We also summarize important findings on the effects of bioactive dietary food components that interact with NO production and affect downstream intestinal epithelium integrity.
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Affiliation(s)
- Kaiwen Mu
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - Shengwu Yu
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - David D Kitts
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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