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Saika F, Fukazawa Y, Kishioka S, Kiguchi N. Characterization of spinal microglial activation in a mouse model of imiquimod-induced psoriasis. J Pharmacol Sci 2023; 153:183-187. [PMID: 37973215 DOI: 10.1016/j.jphs.2023.09.004] [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: 04/14/2023] [Revised: 09/01/2023] [Accepted: 09/15/2023] [Indexed: 11/19/2023] Open
Abstract
Although microglia are associated with chronic pain, the role of spinal microglia in the regulation of itch remains unclear. In this study, we characterized spinal microglial activation in a mouse model of imiquimod (IMQ)-induced psoriasis. Hypertrophic (activated) microglia were observed throughout the spinal cord after the topical application of IMQ. Furthermore, the mRNA expression of microglial markers and inflammatory mediators was upregulated. Ablation of itch-related sensory neurons using resiniferatoxin decreased itch-related scratching behavior and the number of hypertrophic microglia in the spinal dorsal horn. Conclusively, sensory neuron input may partially contribute to spinal microglial activation after IMQ application.
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Affiliation(s)
- Fumihiro Saika
- Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama 640-8392, Japan; Department of Physiological Sciences, School of Pharmaceutical Sciences, Wakayama Medical University, Wakayama 640-8156, Japan
| | - Yohji Fukazawa
- Department of Anatomy, Kansai University of Health Sciences, Osaka 590-0482, Japan
| | - Shiroh Kishioka
- Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama 640-8392, Japan
| | - Norikazu Kiguchi
- Department of Physiological Sciences, School of Pharmaceutical Sciences, Wakayama Medical University, Wakayama 640-8156, Japan.
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Misery L, Pierre O, Le Gall-Ianotto C, Lebonvallet N, Chernyshov PV, Le Garrec R, Talagas M. Basic mechanisms of itch. J Allergy Clin Immunol 2023; 152:11-23. [PMID: 37201903 DOI: 10.1016/j.jaci.2023.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 05/02/2023] [Accepted: 05/11/2023] [Indexed: 05/20/2023]
Abstract
Pruritus (or itch) is an unpleasant sensation leading to a desire to scratch. In the epidermis, there are selective C or Aδ epidermal nerve endings that are pruriceptors. At their other ends, peripheral neurons form synapses with spinal neurons and interneurons. Many areas in the central nervous system are involved in itch processing. Although itch does not occur solely because of parasitic, allergic, or immunologic diseases, it is usually the consequence of neuroimmune interactions. Histamine is involved in a minority of itchy conditions, and many other mediators play a role: cytokines (eg, IL-4, IL-13, IL-31, IL-33, and thymic stromal lymphopoietin), neurotransmitters (eg, substance P, calcitonin gene-related peptide, vasoactive intestinal peptide, neuropeptide Y, NBNP, endothelin 1, and gastrin-releasing peptide), and neurotrophins (eg, nerve growth factor and brain-derived neurotrophic factor). Moreover, ion channels such as voltage-gated sodium channels, transient receptor potential vanilloid 1, transient receptor ankyrin, and transient receptor potential cation channel subfamily M (melastatin) member 8 play a crucial role. The main markers of nonhistaminergic pruriceptors are PAR-2 and MrgprX2. A notable phenomenon is the sensitization to pruritus, in which regardless of the initial cause of pruritus, there is an increased responsiveness of peripheral and central pruriceptive neurons to their normal or subthreshold afferent input in the context of chronic itch.
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Affiliation(s)
- Laurent Misery
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France; Department of Dermatology and Venereology, University Hospital of Brest, Brest, France.
| | - Ophélie Pierre
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France
| | - Christelle Le Gall-Ianotto
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France; Department of Dermatology and Venereology, University Hospital of Brest, Brest, France
| | - Nicolas Lebonvallet
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France
| | - Pavel V Chernyshov
- Department of Dermatology and Venereology, National Medical University, Kiev, Ukraine
| | - Raphaële Le Garrec
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France
| | - Matthieu Talagas
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France; Department of Dermatology and Venereology, University Hospital of Brest, Brest, France
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Structures of human gastrin-releasing peptide receptors bound to antagonist and agonist for cancer and itch therapy. Proc Natl Acad Sci U S A 2023; 120:e2216230120. [PMID: 36724251 PMCID: PMC9963752 DOI: 10.1073/pnas.2216230120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Gastrin releasing peptide receptor (GRPR), a member of the bombesin (BBN) G protein-coupled receptors, is aberrantly overexpressed in several malignant tumors, including those of the breast, prostate, pancreas, lung, and central nervous system. Additionally, it also mediates non-histaminergic itch and pathological itch conditions in mice. Thus, GRPR could be an attractive target for cancer and itch therapy. Here, we report the inactive state crystal structure of human GRPR in complex with the non-peptide antagonist PD176252, as well as two active state cryo-electron microscopy (cryo-EM) structures of GRPR bound to the endogenous peptide agonist gastrin-releasing peptide and the synthetic BBN analog [D-Phe6, β-Ala11, Phe13, Nle14] Bn (6-14), in complex with Gq heterotrimers. These structures revealed the molecular mechanisms for the ligand binding, receptor activation, and Gq proteins signaling of GRPR, which are expected to accelerate the structure-based design of GRPR antagonists and agonists for the treatments of cancer and pruritus.
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Chemogenetics as a neuromodulatory approach to treating neuropsychiatric diseases and disorders. Mol Ther 2022; 30:990-1005. [PMID: 34861415 PMCID: PMC8899595 DOI: 10.1016/j.ymthe.2021.11.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/12/2021] [Accepted: 11/29/2021] [Indexed: 01/01/2023] Open
Abstract
Chemogenetics enables precise, non-invasive, and reversible modulation of neural activity via the activation of engineered receptors that are pharmacologically selective to endogenous or exogenous ligands. With recent advances in therapeutic gene delivery, chemogenetics is poised to support novel interventions against neuropsychiatric diseases and disorders. To evaluate its translational potential, we performed a scoping review of applications of chemogenetics that led to the reversal of molecular and behavioral deficits in studies relevant to neuropsychiatric diseases and disorders. In this review, we present these findings and discuss the potential and challenges for using chemogenetics as a precision medicine-based neuromodulation strategy.
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Kiguchi N, Fukazawa Y, Saika A, Uta D, Saika F, Nakamura TY, Ko M, Kishioka S. Chemogenetic activation of central gastrin-releasing peptide-expressing neurons elicits itch-related scratching behavior in male and female mice. Pharmacol Res Perspect 2021; 9:e00790. [PMID: 34000759 PMCID: PMC8128314 DOI: 10.1002/prp2.790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 04/19/2021] [Indexed: 12/11/2022] Open
Abstract
Several lines of evidence have clarified that the key transmission pathways of itching sensation travel from the periphery to the central nervous system (CNS). Despite the functional significance of gastrin-releasing peptide (GRP) and its cognate receptor in the itch processing mechanism in the spinal dorsal horn (SDH), the roles of GRP-expressing (GRP+ ) neurons in different regions remain unclear. This study aimed to determine whether GRP+ neurons in the CNS directly modulated itch processing. To specifically activate spinal and supraspinal GRP neurons by the designer receptors exclusively activated by designer drugs (DREADDs) system, CAG-LSL-Gq-DREADD mice were crossed with GRP-Cre mice, resulting in the development of GRP-hM3Dq mice. Immunohistochemistry showed that hM3Dq was highly expressed in the SDH and brainstem closely related to sensory processing. The intraperitoneal, intrathecal, or intracerebroventricular administration of clozapine-N-oxide, an agonist of hM3Dq, strongly elicited dermatome-dependent itch-related scratching behavior, but did not change pain sensitivity. Importantly, GRP-Gq-DREADD-mediated scratching behavior in GRP-hM3Dq mice was not affected by the ablation of transient receptor potential vanilloid 1+ sensory C-fibers, and it was also observed to a similar degree under chronic itch conditions. Furthermore, there were no significant sex differences in the scratching behavior elicited by GRP-Gq-DREADD, suggesting that itch-dominant roles of central GRP+ neurons might be common in both sexes, at least under normal physiological conditions. These novel findings not only contribute to understanding the functional roles of central GRP+ neurons further, but also propose the development of future effective therapeutics for intractable itching.
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Affiliation(s)
- Norikazu Kiguchi
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
- Department of Physiological SciencesSchool of Pharmaceutical SciencesWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Yohji Fukazawa
- Department of AnatomyKansai University of Health SciencesSennan‐gunOsakaJapan
| | - Ayano Saika
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Daisuke Uta
- Department of Applied PharmacologyFaculty of Pharmaceutical SciencesUniversity of ToyamaToyama CityToyamaJapan
| | - Fumihiro Saika
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Tomoe Y. Nakamura
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Mei‐Chuan Ko
- Department of Physiology and PharmacologyWake Forest University School of MedicineWinston‐SalemNCUSA
| | - Shiroh Kishioka
- Faculty of Wakayama Health Care SciencesTakarazuka University of Medical and Health CareWakayama CityWakayamaJapan
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Donglang G, Tongtong L, Dan C, Chan Z, Changming W, Guang Y, Yan Y, Zongxiang T. Comparative Study on Different Skin Pruritus Mouse Models. Front Med (Lausanne) 2021; 8:630237. [PMID: 33708782 PMCID: PMC7940346 DOI: 10.3389/fmed.2021.630237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/04/2021] [Indexed: 12/12/2022] Open
Abstract
The animal model is an important tool to study the mechanism of disease formation. Different animal models of pruritus have been adopted based on the purpose of researchers in the study of the itching mechanism. Although the symptoms of various models are quite different, scratching behavior is a key indicator. Therefore, it is necessary to find an animal model that can quickly induce animal scratching and maintain the stability of scratching behavior. In this study, we compared animal models of pruritus induced by four substances and found that the scratching behavior of mice induced by urushiol not only reached the plateau stage quickly but also showed more stability in the plateau phase than that induced by 2,4-dinitrofluorobenzene, oxazolone, and imiquimod. Meanwhile, in the animal model induced by urushiol, the changes of epidermal thickening and inflammatory cell aggregation were also more obvious. In addition, pruritus induced by urushiol is prevalent all over the world, especially in the United States and Europe, involving outdoor groups such as firefighters, forest loggers, and farmers. Therefore, we believe that the urushiol-induced animal model is an ideal choice for the study of the itch formation mechanism and the development of antipruritic drugs.
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Affiliation(s)
- Guan Donglang
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Liu Tongtong
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Chen Dan
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Zhu Chan
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Wang Changming
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yu Guang
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yang Yan
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Tang Zongxiang
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
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Kiguchi N, Saika F, Fukazawa Y, Matsuzaki S, Kishioka S. Critical role of GRP receptor-expressing neurons in the spinal transmission of imiquimod-induced psoriatic itch. Neuropsychopharmacol Rep 2020; 40:287-290. [PMID: 32584520 PMCID: PMC7722649 DOI: 10.1002/npr2.12120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/11/2020] [Accepted: 05/22/2020] [Indexed: 11/08/2022] Open
Abstract
AIM Ample evidence indicates that gastrin-releasing peptide receptor (GRPR)-expressing neurons play a critical role in the transmission of acute itch. However, the pathophysiology of spinal mechanisms underlying intractable itch such as psoriasis remains unclear. In this study, we aimed to determine whether itch-responsive GRPR+ neurons contribute to the spinal transmission of imiquimod (IMQ)-induced psoriatic itch. METHODS To generate a psoriasis model, C57BL/6J mice received a daily topical application of 5% IMQ cream on their shaved back skin for 7-10 consecutive days. GRP+ neurons were inhibited using Cre-dependent expression of Gi-designer receptors exclusively activated by designer drugs (DREADDs), while GRPR+ neurons were ablated by intrathecal administration of bombesin-saporin. RESULTS Repeated topical application of IMQ elicited psoriasis-like dermatitis and scratching behaviors. The mRNA expression levels of GRP and GRPR were upregulated in the cervical spinal dorsal horn (SDH) on days 7 and 10 after IMQ application. Either chemogenetic silencing of GRP+ neurons by Gi-DREADD or ablation of GRPR+ neurons significantly attenuated IMQ-induced scratching behaviors. CONCLUSION The GRP-GRPR system might be enhanced in the SDH, and itch-responsive GRPR+ neurons largely contribute to intractable itch in a mouse model of psoriasis.
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Affiliation(s)
- Norikazu Kiguchi
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Fumihiro Saika
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Yohji Fukazawa
- Department of Anatomy, Kansai University of Health Sciences, Osaka, Japan
| | - Shinsuke Matsuzaki
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Shiroh Kishioka
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan.,Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama, Japan
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