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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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Misery L, Brenaut E, Pierre O, Le Garrec R, Gouin O, Lebonvallet N, Abasq-Thomas C, Talagas M, Le Gall-Ianotto C, Besner-Morin C, Fluhr JW, Leven C. Chronic itch: emerging treatments following new research concepts. Br J Pharmacol 2021; 178:4775-4791. [PMID: 34463358 DOI: 10.1111/bph.15672] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/20/2021] [Accepted: 08/24/2021] [Indexed: 11/29/2022] Open
Abstract
Until recently, itch pathophysiology was poorly understood and treatments were poorly effective in relieving itch. Current progress in our knowledge of the itch processing, the numerous mediators and receptors involved has led to a large variety of possible therapeutic pathways. Currently, inhibitors of IL-31, IL-4/13, NK1 receptors, opioids and cannabinoids, JAK, PDE4 or TRP are the main compounds involved in clinical trials. However, many new targets, such as Mas-related GPCRs and unexpected new pathways need to be also explored.
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Affiliation(s)
- Laurent Misery
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | - Emilie Brenaut
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | | | | | - Olivier Gouin
- LIEN, Univ Brest, Brest, France.,INSERM UMR 1163, Laboratory of Genetic Skin Diseases, Imagine Institute, Paris, France.,University of Paris, Paris, France
| | | | - Claire Abasq-Thomas
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | - Matthieu Talagas
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | | | - Catherine Besner-Morin
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France.,Division of Dermatology, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - Joachim W Fluhr
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France.,Department of Dermatology, Charité Universitätsmedizin, Berlin, Germany
| | - Cyril Leven
- LIEN, Univ Brest, Brest, France.,EA3878, FCRIN INNOVTE, groupe d'étude thrombose Bretagne Occidentale, Brest, France.,Department of Biochemistry and Pharmaco-Toxicology, University Hospital of Brest, Brest, France
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Hon KL, Loo S, Leung AKC, Li JTS, Lee VWY. An overview of drug discovery efforts for eczema: why is this itch so difficult to scratch? Expert Opin Drug Discov 2020; 15:487-498. [PMID: 32050818 DOI: 10.1080/17460441.2020.1722639] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Introduction: Atopic dermatitis (AD) is a type of allergic/inflammatory dermatitis characterized by itch and an impairment in quality of life.Areas covered: Herein, the authors review drug discovery efforts for AD, highlighting the clinical efficacy of novel drugs, with a particular focus on the relief of pruritus. Topical agents include emollients, topical antihistamines, corticosteroids, calcineurin inhibitors and herbs. Recently, topical phosphodiesterase E4 (PDE4) inhibitors like crisaborole have become available and are efficacious for mild to moderate AD with few side effects. For more severe AD, monoclonal antibodies like dupilumab are considered as efficacious subcutaneous treatment options. In severe and recalcitrant AD, systemic treatment can ameliorate AD symptoms.Expert opinion: Many topical and systemic medications have demonstrated therapeutic benefits for AD. Indeed, randomized trials have shown that topical PDE4 inhibitors and subcutaneous dupilumab are safe and efficacious. Objective tools to evaluate itch and gauge treatment efficacy is important, but current methodology relies primarily on clinical scores. AD is a systemic atopic disease with a lot of complicated psychosocial issues. Suboptimal efficacy is often due to poor compliance and unrealistic expectation of curative treatment, rendering treatment difficult despite the existence of effective medications.
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Affiliation(s)
- Kam Lun Hon
- Department of Paediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.,The Hong Kong Institute of Integrative Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Steven Loo
- The Hong Kong Institute of Integrative Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Alexander K C Leung
- Department of Pediatrics, The University of Calgary, Alberta Children's Hospital, Calgary, Alberta, Canada
| | - Joyce T S Li
- Centre for Learning Enhancement And Research, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Vivian W Y Lee
- Centre for Learning Enhancement And Research, The Chinese University of Hong Kong, Shatin, Hong Kong
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New therapies for atopic dermatitis: Additional treatment classes. J Am Acad Dermatol 2018; 78:S76-S83. [DOI: 10.1016/j.jaad.2017.12.024] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/08/2017] [Accepted: 12/09/2017] [Indexed: 12/13/2022]
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Jung MJ, Choi YW, Chung BY, Park CW, Kim HO. Pathophysiology and new treatment of itch. JOURNAL OF THE KOREAN MEDICAL ASSOCIATION 2018. [DOI: 10.5124/jkma.2018.61.11.670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Min Je Jung
- Department of Dermatology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Yong Won Choi
- Department of Dermatology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Bo Young Chung
- Department of Dermatology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Chun Wook Park
- Department of Dermatology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Hye One Kim
- Department of Dermatology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
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Rossbach K, Schaper K, Kloth C, Gutzmer R, Werfel T, Kietzmann M, Bäumer W. Histamine H4 receptor knockout mice display reduced inflammation in a chronic model of atopic dermatitis. Allergy 2016; 71:189-97. [PMID: 26440543 DOI: 10.1111/all.12779] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2015] [Indexed: 12/22/2022]
Abstract
BACKGROUND The histamine H4 receptor (H4R) was brought into focus as a new therapeutic target for the treatment of allergic disorders such as atopic dermatitis (AD). H4R antagonists have already been tested in several animal models of AD, but these studies have yielded conflicting results. MATERIAL AND METHODS The development of ovalbumin-induced AD-like skin lesions was analysed in H4R(-/-) mice and in H4R antagonist (JNJ28307474)-treated mice. RESULTS H4R(-/-) mice showed a clear amelioration of the skin lesions, with a diminished influx of inflammatory cells and a reduced epidermal hyperproliferation at lesional skin sites. H4R(-/-) mice had a reduced amount of ovalbumin-specific IgE, a reduced number of splenocytes and lymph node cells with a decreased number of CD4+ T cells. The H4R modulated the cytokine secretion of CD4+ T cells and splenocytes and altered the cellular profile in the lymph nodes. The anti-inflammatory effect could only partially be mimicked by JNJ28307474 and only when the H4R antagonist was given during sensitization and challenge and not when JNJ28307474 was only given during the provocation phase of the allergic reaction. CONCLUSION The H4R modulates inflammation in a chronic allergic dermatitis setting. However, results of this study indicate that it is necessary to block the H4R during ontogeny and development of the allergic inflammation.
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Affiliation(s)
- K. Rossbach
- Institute for Pharmacology, Toxicology and Pharmacy; University of Veterinary Medicine; Hannover Germany
| | - K. Schaper
- Division of Immunodermatology and Allergy Research; Department of Dermatology and Allergy; Hannover Medical School; Hannover Germany
| | - Ch. Kloth
- Institute for Pharmacology; Hannover Medical School; Hannover Germany
| | - R. Gutzmer
- Division of Immunodermatology and Allergy Research; Department of Dermatology and Allergy; Hannover Medical School; Hannover Germany
| | - T. Werfel
- Division of Immunodermatology and Allergy Research; Department of Dermatology and Allergy; Hannover Medical School; Hannover Germany
| | - M. Kietzmann
- Institute for Pharmacology, Toxicology and Pharmacy; University of Veterinary Medicine; Hannover Germany
| | - W. Bäumer
- Institute for Pharmacology, Toxicology and Pharmacy; University of Veterinary Medicine; Hannover Germany
- Department of Molecular Biomedical Sciences; College of Veterinary Medicine; NC State University; Raleigh NC USA
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Mediators of Chronic Pruritus in Atopic Dermatitis: Getting the Itch Out? Clin Rev Allergy Immunol 2015; 51:263-292. [DOI: 10.1007/s12016-015-8488-5] [Citation(s) in RCA: 200] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Abstract
Pruritus is defined as "an unpleasant sensation that causes the need to scratch". This is not a small pain. It seems that pruriceptors exist but their level of separation from nociceptive receptors is still debated. Pathways of pruritus were identified from the skin (around the dermo-epidermal junction) to the brain. Many mediators are involved in pruritus but there are at least a histaminergic and a non-histaminergic pathway (PAR-2dependent). Similarly to pain, gate control or peripheral and central sensitization mechanisms have been highlighted in pruritus. These pathophysiological advances are important and anticipate therapeutic advances, that will be very useful for the symptomatic treatment of pruritus (poorly efficient at present).
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Affiliation(s)
- Laurent Misery
- Laboratoire des neurosciences de Brest (EA4685), université de Bretagne occidentale, faculté de médecine, rue Camille Desmoulins, 29200 Brest, France service de dermatologie, CHU de Brest, 2, avenue Foch, 29200 Brest, France
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Abstract
Pruritus, also known as itch, is a very common, unpleasant sensation that elicits an urge to scratch. Its origin is not always in the skin, and neuropathic itch that is caused by neuronal or glial damage is common, but poorly understood by both dermatologists and neurologists. Although pruritus has not been considered as serious a symptom as pain, it is difficult to treat and--if chronic--can severely impair quality of life. Neuropathic itch is often associated with other clinical symptoms, most commonly neuropathic pain, and hypersensitization to stimuli is present in both pruritus and pain of neuropathic origin. The shared aetiology can aid in finding suitable treatment for itch in some cases, but more detailed knowledge of the mechanisms of itch, along with standardized, well-controlled trials, is needed. Pruritus research is an emerging but currently very active field, and our understanding of this sensation is rapidly increasing. Here, we review new discoveries regarding the role of the nervous system and the contribution of different pathways in pruritus, discuss the different aetiologies of neuropathic itch, and outline currently available and potential strategies for managing neuropathic pruritus.
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Rossbach K, Bäumer W. PCR detects bands consistent with the expression of receptors associated with pruritus in canine dorsal root ganglia. Vet Dermatol 2013; 25:9-e4. [PMID: 24289149 DOI: 10.1111/vde.12093] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2013] [Indexed: 01/17/2023]
Abstract
BACKGROUND Various mediators are involved in the induction of itch, i.e. pruritus; however, the in vivo pharmacology of pruritus seems to be different in distinct species, and little is known about receptors that are involved in the induction of itch in dogs. The species differences in the mediation of pruritus might be explained by species differences in receptor expression in the sensory nerves, including the dorsal root ganglia (DRG). HYPOTHESIS/OBJECTIVES The aim of the study was to analyse the expression of receptors for various mediators of pruritus in canine DRG. METHODS Dorsal root ganglia of 14 dogs, which were euthanized for reasons not related to this study, were analysed. Multiple DRG per dog were dissected and, after homogenization of the DRG tissues, total RNA was isolated, reverse transcribed to complementary DNA and amplified with custom-synthesized primers. RESULTS The following receptors were found in canine DRG: transient receptor potential cation channel subfamily V member 1, tachykinin receptor 1, Toll-like receptor 7, endothelin receptor type A, opioid receptors μ1 and κ1, histamine H1 -H4 receptors and the interleukin-31 receptor complex. CONCLUSIONS AND CLINICAL IMPORTANCE PCR analysis detected bands consistent with the expression of receptors associated with pruritus in canine DRG.
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Affiliation(s)
- Kristine Rossbach
- Institute of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany
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Tey HL, Yosipovitch G. Targeted treatment of pruritus: a look into the future. THE BRITISH JOURNAL OF DERMATOLOGY 2011. [PMID: 21219293 DOI: 10.1111/j.1365-2133.2011.10217.x.] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances in pruritus research have elucidated mediators and neuronal pathways involved in itch transmission, and this fast emerging knowledge may possibly be translated into new therapies in the near future. In the skin and peripheral nerves, potential mediator and receptor therapeutic targets include the H4 histamine receptor, protease-activated receptor 2, serine proteases, cathepsin S, peripheral mu- and kappa-opioid receptors, interleukin-31, transient receptor potential vanilloid 1 and 3, fatty acid amide hydrolase, nerve growth factor and its receptor, acetylcholine, and the Mas-related G protein-coupled receptors. In the spinal cord, gastrin-related peptide and its receptor, as well as substance P and its receptor neurokinin receptor-1 serve as potential therapeutic targets. In the brain, reduction of itch perception and modulation of emotions may possibly be achieved through drugs acting on the anterior cingulate cortex. Clinically, management of pruritus should be instituted early and should address the skin pathology, peripheral neuropathy, central sensitization, and the cognito-affective aspects of the disease.
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Affiliation(s)
- H L Tey
- Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1071, USA
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Abstract
Recent advances in pruritus research have elucidated mediators and neuronal pathways involved in itch transmission, and this fast emerging knowledge may possibly be translated into new therapies in the near future. In the skin and peripheral nerves, potential mediator and receptor therapeutic targets include the H4 histamine receptor, protease-activated receptor 2, serine proteases, cathepsin S, peripheral mu- and kappa-opioid receptors, interleukin-31, transient receptor potential vanilloid 1 and 3, fatty acid amide hydrolase, nerve growth factor and its receptor, acetylcholine, and the Mas-related G protein-coupled receptors. In the spinal cord, gastrin-related peptide and its receptor, as well as substance P and its receptor neurokinin receptor-1 serve as potential therapeutic targets. In the brain, reduction of itch perception and modulation of emotions may possibly be achieved through drugs acting on the anterior cingulate cortex. Clinically, management of pruritus should be instituted early and should address the skin pathology, peripheral neuropathy, central sensitization, and the cognito-affective aspects of the disease.
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Affiliation(s)
- H L Tey
- Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1071, USA
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Fallahzadeh MK, Roozbeh J, Geramizadeh B, Namazi MR. Interleukin-2 serum levels are elevated in patients with uremic pruritus: a novel finding with practical implications. Nephrol Dial Transplant 2011; 26:3338-44. [PMID: 21372257 DOI: 10.1093/ndt/gfr053] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Uremic pruritus (UP) is still a common tormenting symptom among patients on hemodialysis (HD). The pathogenesis of UP is complex and not fully clarified. Some preliminary studies indicate that UP is a systemic inflammatory disease with a deranged balance of T helper (TH) cell differentiation toward TH1 predominance. The aim of this study was to further elucidate the potential contribution of TH1 cytokines to the pathogenesis of UP. METHODS In this study, 112 HD patients were screened for UP. After meeting the required criteria, 31 HD patients with UP were included in the study as case group and 30 age- and sex-matched HD patients without UP were enrolled as controls. The serum levels of interleukin (IL)-2 and interferon-γ (as TH1 cytokines), IL-4 (as a TH-2 cytokine), high-sensitive C-reactive protein (as an inflammatory marker), parathyroid hormone, calcium, phosphate, albumin and ferritin were measured in all patients. Moreover, blood variables including hemoglobin and mean corpuscular volume were also determined. The correlations of measured factors with UP severity were determined as well. RESULTS Except for the serum levels of IL-2, which were significantly higher in HD patients with itch versus those without it [0.544 ± 0.126 (U/mL) versus 0.318 ± 0.145 (U/mL); P < 0.0001], no statistically significant difference was observed in the levels of each of the above-mentioned factors between the two groups. Additionally, no correlation was detected between the levels of measured factors and UP severity. CONCLUSIONS The results of our study, for the first time, point to the potential important role of IL-2 in UP and further support the notion of TH1 overactivity in its pathogenesis. Our study paves the way for further studies focusing on the contribution of IL-2 to the UP, such as the experimental use of anti-IL-2 receptor antibodies.
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HIRAKAWA N, YANOSHITA R, YOSHII M, YANO H. Relation between Cooling Sheet Effect and Tear Histamine Concenration in Allergic Conjunctivitis. YAKUGAKU ZASSHI 2010; 130:971-5. [DOI: 10.1248/yakushi.130.971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Abstract
Itch, the hallmark of atopic dermatitis, has a significant impact on quality of life for patients with this disease. Various central and peripheral mediators have been suggested to play a role in the pathophysiology of atopic eczema itch. Significant cross-talk occurs among stratum corneum, keratinocytes, immune cells, and nerve fibers, which are in close proximity to one another and induce itch. The impaired barrier function associated with the itch-scratch cycle further augments this vicious cycle. Recent advances in our understanding of itch pathophysiology shed light on peripheral and central neural sensitization of nerve fibers that contribute significantly to itch in atopic dermatitis. Recently, several new mediators have been described as associated with itch in atopic dermatitis, including serine proteases, interleukin 31, and nerve growth factor. This review covers the peripheral and central mechanisms and mediators involved in pathogenesis of itch in atopic dermatitis.
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