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Bao C, Abraham SN. Mast cell-sensory neuron crosstalk in allergic diseases. J Allergy Clin Immunol 2024; 153:939-953. [PMID: 38373476 PMCID: PMC10999357 DOI: 10.1016/j.jaci.2024.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 01/12/2024] [Accepted: 02/14/2024] [Indexed: 02/21/2024]
Abstract
Mast cells (MCs) are tissue-resident immune cells, well-positioned at the host-environment interface for detecting external antigens and playing a critical role in mobilizing innate and adaptive immune responses. Sensory neurons are afferent neurons innervating most areas of the body but especially in the periphery, where they sense external and internal signals and relay information to the brain. The significance of MC-sensory neuron communication is now increasingly becoming recognized, especially because both cell types are in close physical proximity at the host-environment interface and around major organs of the body and produce specific mediators that can activate each other. In this review, we explore the roles of MC-sensory neuron crosstalk in allergic diseases, shedding light on how activated MCs trigger sensory neurons to initiate signaling in pruritus, shock, and potentially abdominal pain in allergy, and how activated sensory neurons regulate MCs in homeostasis and atopic dermatitis associated with contact hypersensitivity and type 2 inflammation. Throughout the review, we also discuss how these 2 sentinel cell types signal each other, potentially resulting in a positive feedback loop that can sustain inflammation. Unraveling the mysteries of MC-sensory neuron crosstalk is likely to unveil their critical roles in various disease conditions and enable the development of new therapeutic approaches to combat these maladies.
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Affiliation(s)
- Chunjing Bao
- Department of Pathology, Duke University Medical Center, Durham, NC
| | - Soman N Abraham
- Department of Pathology, Duke University Medical Center, Durham, NC; Department of Immunology, Duke University Medical Center, Durham, NC; Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC; Department of Program in Emerging Infectious Diseases, Duke-National University of Singapore, Singapore, Singapore.
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Renkhold L, Wiegmann H, Pfleiderer B, Süer A, Zeidler C, Pereira MP, Schmelz M, Ständer S, Agelopoulos K. Scratching increases epidermal neuronal branching and alters psychophysical testing responses in atopic dermatitis and brachioradial pruritus. Front Mol Neurosci 2023; 16:1260345. [PMID: 37795274 PMCID: PMC10546039 DOI: 10.3389/fnmol.2023.1260345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 08/25/2023] [Indexed: 10/06/2023] Open
Abstract
Background Chronic scratching imposes a major stress on the skin and can lead to itch intensity worsening, and consequently, patients may enter an itch-scratch cycle. This repetitive mechanical stress can result in lichenification, worsening of epidermal barrier function, and enhanced cutaneous inflammation. Furthermore, a reduction of intraepidermal nerve fibers was previously described in lichenification. Aim The aim of this study was to investigate the influence of chronic scratching on the epidermal neuroanatomy and on sensory changes, in particular the prevalence of hyperknesis and alloknesis in patients after mechanical, chemical, and electrical stimuli. Methods Analyses were performed on pruritic lichenified (chronically scratched), pruritic non-lichenified (not chronically scratched), and non-pruritic non-lesional (unaffected) skin areas of patients with inflammatory pruritus, i.e., atopic dermatitis (n = 35), and neuropathic pruritus, i.e., brachioradial pruritus (n = 34) vs. healthy matched controls (n = 64). Our fine-grained spatial skin characterization enabled specifically studying the differential effects of chronic scratching in inflammatory and neuropathic itch. Results Analysis of intraepidermal nerve fiber density showed rarefaction of fibers in all three skin areas of patients compared with healthy controls in both diagnoses. Even more, the two pruritic areas had significantly less nerve fibers than the unaffected skin, whereas electrically induced itch was massively increased. Epidermal branching of the remaining nerve fibers in lichenified/chronically scratched skin was increased, particularly in patients with brachioradial pruritus, which may contribute to the pronounced local neuronal sensitivity. Hyperknesis and alloknesis were found to increase independently of lichenification. Conclusion Our results indicate that chronic scratching may not affect intraepidermal nerve fiber density but leads to a stronger branching pattern of intraepidermal nerve fibers, which may contribute to local hypersensitivity. The increased sensitivity in the pruritic areas suggests mechanisms of peripheral sensitization, whereas the increased sensation of electrically and chemically induced itch in unaffected skin indicates central sensitization for itch.
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Affiliation(s)
- Lina Renkhold
- Department of Dermatology and Centre for Chronic Pruritus, University Hospital Münster, Münster, Germany
| | - Henning Wiegmann
- Department of Dermatology and Centre for Chronic Pruritus, University Hospital Münster, Münster, Germany
| | - Bettina Pfleiderer
- Clinic of Radiology, Medical Faculty, University Hospital Münster, University of Münster, Münster, Germany
| | - Aysenur Süer
- Institute of Medical Informatics, University of Münster, Münster, Germany
| | - Claudia Zeidler
- Department of Dermatology and Centre for Chronic Pruritus, University Hospital Münster, Münster, Germany
| | - Manuel P. Pereira
- Institute of Allergology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Allergology and Immunology, Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Berlin, Germany
| | - Martin Schmelz
- Department of Experimental Pain Research, MCTN, Faculty of Medicine Mannheim, University of Heidelberg, Mannheim, Germany
| | - Sonja Ständer
- Department of Dermatology and Centre for Chronic Pruritus, University Hospital Münster, Münster, Germany
| | - Konstantin Agelopoulos
- Department of Dermatology and Centre for Chronic Pruritus, University Hospital Münster, Münster, Germany
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Pakalniskis J, Soares S, Rajan S, Vyshnevska A, Schmelz M, Solinski HJ, Rukwied R, Carr R. Human pain ratings to electrical sinusoids increase with cooling through a cold-induced increase in C-fibre excitability. Pain 2023; 164:1524-1536. [PMID: 36972485 DOI: 10.1097/j.pain.0000000000002849] [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: 05/04/2022] [Accepted: 12/01/2022] [Indexed: 03/29/2023]
Abstract
ABSTRACT Low-frequency sinusoidal current applied to human skin evokes local axon reflex flare and burning pain, indicative of C-fibre activation. Because topical cooling works well as a local analgesic, we examined the effect of cooling on human pain ratings to sinusoidal and rectangular profiles of constant current stimulation. Unexpectedly, pain ratings increased upon cooling the skin from 32 to 18°C. To explore this paradoxical observation, the effects of cooling on C-fibre responses to stimulation with sinusoidal and rectangular current profiles were determined in ex vivo segments of mouse sural and pig saphenous nerve. As expected by thermodynamics, the absolute value of electrical charge required to activate C-fibre axons increased with cooling from 32°C to 20°C, irrespective of the stimulus profile used. However, for sinusoidal stimulus profiles, cooling enabled a more effective integration of low-intensity currents over tens of milliseconds resulting in a delayed initiation of action potentials. Our findings indicate that the paradoxical cooling-induced enhancement of electrically evoked pain in people can be explained by an enhancement of C-fibre responsiveness to slow depolarization at lower temperatures. This property may contribute to symptoms of enhanced cold sensitivity, especially cold allodynia, associated with many forms of neuropathic pain.
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Affiliation(s)
- Julius Pakalniskis
- Department of Experimental Pain Research, Mannheim Centre for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Schneider T, Filip J, Soares S, Sohns K, Carr R, Rukwied R, Schmelz M. Optimized Electrical Stimulation of C-Nociceptors in Humans Based on the Chronaxie of Porcine C-Fibers. THE JOURNAL OF PAIN 2023; 24:957-969. [PMID: 36681314 DOI: 10.1016/j.jpain.2023.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/21/2022] [Accepted: 01/10/2023] [Indexed: 01/20/2023]
Abstract
Classically, to electrically excite C-nociceptors, rectangular pulses are used with a duration close to the estimated chronaxie of C-fibres (about 2 ms). Recent results using slow depolarizing stimuli suggest longer chronaxies. We therefore set out to optimize C-fiber stimulation based on recordings of single C-nociceptors in-vivo and C-fiber compound-action-potentials (C-CAP) ex-vivo using half-sine shaped stimuli of durations between 1 and 250ms. Single fiber (n = 45) recording in pigs revealed high chronaxie values for C-touch fibers (15.8 ms), polymodal- (14.2 ms) and silent-nociceptors (16.8 ms). Activation thresholds decreased 2 to 3-fold in all fibre classes when increasing the duration of half-sine pulses from 1 to 25 ms (P < .05). C-CAPs strength-duration curves of the pig saphenous nerve (n = 7) showed the highest sensitivity for half-sine durations between 10 and 25 ms. Half-maximum currents for C-CAPS were reduced 3-fold compared to rectangular pulses (P < .01) whereas the opposite was found for A-fiber compound action potentials. Psychophysics in humans (n = 23) revealed that half-sine stimulus durations >10 ms reduced detection thresholds, pain thresholds, and stimulus current amplitudes required to generate a pain rating of 3 on an 11-point Numeric Rating Scale (NRS) as compared to 1 ms rectangular pulses (P < 0.05). Increasing the duration from 1 to 25 ms led to a 4-fold amplitude reduction for pain-thresholds and stimuli caused an axon-reflex flare. Excitability of single polymodal nociceptors in animals paralleled human psychophysics and we conclude optimized half-sine pulses facilitate C-nociceptor activation. PERSPECTIVE: Electrical stimulation with longer lasting half-sine wave pulses preferentially activates C-nociceptors and changes in the strength duration curve may identify nociceptor hyperexcitability in patients with neuropathic pain.
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Affiliation(s)
- Tobias Schneider
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany; Chronic Pain Unit, Department of Anesthesiology, University Hospital Basel, Basel, Switzerland.
| | - Julia Filip
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Sabrina Soares
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Kyra Sohns
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Richard Carr
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Roman Rukwied
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Martin Schmelz
- Department of Experimental Pain Research, Mannheim Center Translational Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
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Wang S, Su Q, Qin W, Yu C, Liang M. Both fine-grained and coarse-grained spatial patterns of neural activity measured by functional MRI show preferential encoding of pain in the human brain. Neuroimage 2023; 272:120049. [PMID: 36963739 DOI: 10.1016/j.neuroimage.2023.120049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/31/2023] [Accepted: 03/21/2023] [Indexed: 03/26/2023] Open
Abstract
How pain emerges from human brain remains an unresolved question in pain neuroscience. Neuroimaging studies have suggested that all brain areas activated by painful stimuli were also activated by tactile stimuli, and vice versa. Nonetheless, pain-preferential spatial patterns of voxel-level activation in the brain have been observed when distinguishing painful and tactile brain activations using multivariate pattern analysis (MVPA). According to two hypotheses, the neural activity pattern preferentially encoding pain could exist at a global, coarse-grained, regional level, corresponding to the "pain connectome" hypothesis proposing that pain-preferential information may be encoded by the synchronized activity across multiple distant brain regions, and/or exist at a local, fine-grained, voxel level, corresponding to the "intermingled specialized/preferential neurons" hypothesis proposing that neurons responding specially or preferentially to pain could be present and intermingled with non-pain neurons within a voxel. Here, we systematically investigated the spatial scales of pain-distinguishing information in the human brain measured by fMRI using machine learning techniques, and found that pain-distinguishing information could be detected at both coarse-grained spatial scales across widely distributed brain regions and fine-grained spatial scales within many local areas. Importantly, the spatial distribution of pain-distinguishing information in the brain varies across individuals and such inter-individual variations may be related to a person's trait about pain perception, particularly the pain vigilance and awareness. These results provide new insights into the long-standing question of how pain is represented in the human brain and help the identification of characteristic neuroimaging measurements of pain.
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Affiliation(s)
- Sijia Wang
- School of Medical Technology, School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Cosponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin 300070, China
| | - Qian Su
- Department of Molecular Imaging and Nuclear Medicine, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for China, Tianjin 300060, China
| | - Wen Qin
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Chunshui Yu
- School of Medical Technology, School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Cosponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin 300070, China; Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Meng Liang
- School of Medical Technology, School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Cosponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin 300070, China.
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Landmann G, Stockinger L, Gerber B, Benrath J, Schmelz M, Rukwied R. Local hyperexcitability of C-nociceptors may predict responsiveness to topical lidocaine in neuropathic pain. PLoS One 2022; 17:e0271327. [PMID: 35834539 PMCID: PMC9282664 DOI: 10.1371/journal.pone.0271327] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/28/2022] [Indexed: 12/03/2022] Open
Abstract
We explored whether increased C-nociceptor excitability predicts analgesic effects of topical lidocaine in 33 patients with mono- (n = 15) or poly-neuropathy (n = 18). Excitability of C-nociceptors was tested by transcutaneous electrical sinusoidal (4 Hz) and half sine wave (single 500 ms pulse) stimulation delivered to affected and non-affected sites. Analgesic effects of 24 hrs topical lidocaine were recorded. About 50% of patients reported increased pain from symptomatic skin upon continuous 4 Hz sinusoidal and about 25% upon 500 ms half sine wave stimulation. Electrically-evoked half sine wave pain correlated to their clinical pain level (r = 0.37, p < 0.05). Lidocaine-patches reduced spontaneous pain by >1-point NRS in 8 of 28 patients (p < 0.0001, ANOVA). Patients with increased pain to 2.5 sec sinusoidal stimulation at 0.2 and 0.4 mA intensity had significantly stronger analgesic effects of lidocaine and in reverse, patients with a pain reduction of >1 NRS had significantly higher pain ratings to continuous 1 min supra-threshold sinusoidal stimulation. In the assessed control skin areas of the patients, enhanced pain upon 1 min 4 Hz stimulation correlated to increased depression scores (HADS). Electrically assessed C-nociceptor excitability identified by slowly depolarizing electrical stimuli might reflect the source of neuropathic pain in some patients and can be useful for patient stratification to predict potential success of topical analgesics. Central neuronal circuitry assessment reflected by increased pain in control skin associated with higher HADS scores suggest central sensitization phenomena in a sub-population of neuropathic pain patients.
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Affiliation(s)
- Gunther Landmann
- Centre for Pain Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland
| | - Lenka Stockinger
- Centre for Pain Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland
| | - Benjamin Gerber
- Department of Anesthesiology and Intensive Care, University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Justus Benrath
- Department of Anesthesiology and Intensive Care, University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Martin Schmelz
- Department of Experimental Pain Research, Mannheim Center for Translational Neurosciences, Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Roman Rukwied
- Department of Experimental Pain Research, Mannheim Center for Translational Neurosciences, Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
- * E-mail:
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7
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Zhao R, Su Q, Song Y, Yang Q, Wang S, Zhang J, Qin W, Yu C, Liang M. Brain-activation-based individual identification reveals individually unique activation patterns elicited by pain and touch. Neuroimage 2022; 260:119436. [PMID: 35788043 DOI: 10.1016/j.neuroimage.2022.119436] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 06/28/2022] [Accepted: 06/30/2022] [Indexed: 11/15/2022] Open
Abstract
Pain is subjective and perceived differently in different people. However, individual differences in pain-elicited brain activations are largely overlooked and often discarded as noises. Here, we used a brain-activation-based individual identification procedure to investigate the uniqueness of the activation patterns within the whole brain or brain regions elicited by nociceptive (laser) and tactile (electrical) stimuli in each of 62 healthy participants. Specifically, brain activation patterns were used as "fingerprints" to identify each individual participant within and across sensory modalities, and individual identification accuracy was calculated to measure each individual's identifiability. We found that individual participants could be successfully identified using their brain activation patterns elicited by nociceptive stimuli, tactile stimuli, or even across modalities. However, different participants had different identifiability; importantly, the within-pain, but not within-touch or cross-modality, individual identifiability obtained from three brain regions (i.e., the left superior frontal gyrus, the middle temporal gyrus and the insular gyrus) were inversely correlated with the scores of Pain Vigilance and Awareness Questionnaire (i.e., how a person is alerted to pain) across participants. These results suggest that each individual has a unique pattern of brain responses to nociceptive stimuli which contains both modality-nonspecific and pain-specific information and may be associated with pain-related behaviors shaped by his/her own personal experiences and highlight the importance of a transition from group-level to individual-level characterization of brain activity in neuroimaging studies.
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Affiliation(s)
- Rui Zhao
- School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, 300070, China; Department of Orthopedics Surgery, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Qian Su
- Department of Molecular Imaging and Nuclear Medicine, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for China, Tianjin 300060, China
| | - YingChao Song
- School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, 300070, China
| | - QingQing Yang
- School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, 300070, China; Department of Radiology, Zhejiang University School of Medicine First Affiliated Hospital, Zhejiang 310009, China
| | - Sijia Wang
- School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, 300070, China
| | - Juan Zhang
- Department of Prosthodontics, School and Hospital of Stomatology, Tianjin Medical University, Tianjin, 300070, China
| | - Wen Qin
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Chunshui Yu
- School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, 300070, China
| | - Meng Liang
- School of Medical Imaging, Tianjin Key Laboratory of Functional Imaging, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, 300070, China.
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Strand N, Wie C, Peck J, Maita M, Singh N, Dumbroff J, Tieppo Francio V, Murphy M, Chang K, Dickerson DM, Maloney J. Small Fiber Neuropathy. Curr Pain Headache Rep 2022; 26:429-438. [PMID: 35384587 DOI: 10.1007/s11916-022-01044-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/28/2022] [Indexed: 12/20/2022]
Abstract
PURPOSE OF REVIEW This narrative review aims to summarize advances in the field of small fiber neuropathy made over the last decade, with emphasis on novel research highlighting the distinctive features of SFN. RECENT FINDINGS While the management of SFNs is ideally aimed at treating the underlying cause, most patients will require pain control via multiple, concurrent therapies. Herein, we highlight the most up-to-date information for diagnosis, medication management, interventional management, and novel therapies on the horizon. Despite the prevalence of small fiber neuropathies, there is no clear consensus on guidelines specific for the treatment of SFN. Despite the lack of specific guidelines for SFN treatment, the most recent general neuropathic pain guidelines are based on Cochrane studies and randomized controlled trials (RCTs) which have individually examined therapies used for the more commonly studied SFNs, such as painful diabetic neuropathy and HIV neuropathy. The recommendations from current guidelines are based on variables such as number needed to treat (NNT), safety, ease of use, and effect on quality of life.
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Affiliation(s)
- N Strand
- Division of Pain Medicine, Mayo Clinic Hospital, Phoenix, AZ, USA.
| | - C Wie
- Division of Pain Medicine, Mayo Clinic Hospital, Phoenix, AZ, USA
| | - J Peck
- Performing Arts Medicine Department, Shenandoah University, Winchester, USA
| | - M Maita
- Division of Pain Medicine, Mayo Clinic Hospital, Phoenix, AZ, USA
| | - N Singh
- OrthoAlabama Spine and Sports, Birmingham, AL, USA
| | - J Dumbroff
- Mount Sinai Morningside and West Department of Anesthesiology, New York, NY, USA
| | - V Tieppo Francio
- Department of Rehabilitation on Medicine, The University of Kansas Medical Center, Kansas City, KS, USA
| | - M Murphy
- Department of Rehabilitation on Medicine, The University of Kansas Medical Center, Kansas City, KS, USA
| | - K Chang
- Department of Anesthesiology and Critical Care, Emory University, Atlanta, GA, USA
| | - D M Dickerson
- NorthShore University HealthSystem, Evanston, IL, USA
- University of Chicago Medicine, Chicago,, IL, USA
| | - J Maloney
- Division of Pain Medicine, Mayo Clinic Hospital, Phoenix, AZ, USA
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Jonas R, Schmelz M. Sensitization of supra-threshold pain responses-Translational aspects and mechanisms. FRONTIERS IN NETWORK PHYSIOLOGY 2022; 2:1078890. [PMID: 36926107 PMCID: PMC10013001 DOI: 10.3389/fnetp.2022.1078890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022]
Abstract
A substantial translational gap in pain research has been reflected by a mismatch of relevant primary pain assessment endpoints in preclinical vs. clinical trials. Since activity-dependent mechanisms may be neglected during reflexive tests, this may add as a confounding factor during preclinical pain assessment. In this perspective, we consider the evidence for a need for supra-threshold pain assessment in the pain research literature. In addition to that, we focus on previous results that may demonstrate an example mechanism, where the detection of neuron-glial interactions on pain seems to be substantially depending on the assessment of pain intensity beyond threshold levels.
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Affiliation(s)
- Robin Jonas
- Department of Translational Pharmacology, Medical School EWL, Bielefeld University, Bielefeld, Germany.,UMCG Pain Center, Department of Anaesthesiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Martin Schmelz
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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Microinjection of pruritogens in NGF-sensitized human skin. Sci Rep 2021; 11:21490. [PMID: 34728705 PMCID: PMC8563721 DOI: 10.1038/s41598-021-00935-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/19/2021] [Indexed: 11/16/2022] Open
Abstract
Single intradermal injections of nerve growth factor (NGF) evoke prolonged but temporally distinct sensitization patterns to somatosensory stimuli. Focal administration of the non-histaminergic pruritogen cowhage but not histamine resulted in elevated itch at day 21 after NGF administration. Here, we injected bovine adrenal medulla peptide 8–22 (BAM8–22), β-alanine (β-ALA) and endothelin-1 (ET-1) into NGF-treated skin of 11 healthy volunteers and investigated the corresponding itch/pain and flare reactions. β-ALA was the weakest pruritogen, while BAM8–22 and ET-1 were equally potent as histamine. NGF did not sensitize itch or flare reactions induced by any compound, but injection and evoked pain were increased at day 21 and 49. The involvement of histamine H1 receptors in itch was explored in eight subjects after oral cetirizine. ET-1-induced itch and flare were significantly reduced. BAM8–22 and β-ALA itch were not affected, but flare responses after BAM8–22 reduced by 50%. The results indicate that a single NGF injection does not sensitize for experimentally induced itch but increases pain upon pruritogen injection. In healthy humans, pruritic and algetic processing appear differentially regulated by NGF. However, in patients suffering chronic itch, prolonged elevation of NGF-levels under inflammatory conditions may contribute to elevated itch.
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11
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Chang CH, Chang YS, Hsieh YL. Transient receptor potential vanilloid subtype 1 depletion mediates mechanical allodynia through cellular signal alterations in small-fiber neuropathy. Pain Rep 2021; 6:e922. [PMID: 34585035 PMCID: PMC8462592 DOI: 10.1097/pr9.0000000000000922] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/22/2021] [Accepted: 02/22/2021] [Indexed: 12/27/2022] Open
Abstract
Transient receptor potential vanilloid subtype 1 (TRPV1) is a polymodal nociceptor that monitors noxious thermal sensations. Few studies have addressed the role of TRPV1 in mechanical allodynia in small-fiber neuropathy (SFN) caused by sensory nerve damage. Accordingly, this article reviews the putative mechanisms of TRPV1 depletion that mediates mechanical allodynia in SFN. The intraepidermal nerve fibers (IENFs) degeneration and sensory neuronal injury are the primary characteristics of SFN. Intraepidermal nerve fibers are mainly C-polymodal nociceptors and Aδ-fibers, which mediated allodynic pain after neuronal sensitization. TRPV1 depletion by highly potent neurotoxins induces the upregulation of activating transcription factor 3 and IENFs degeneration which mimics SFN. TRPV1 is predominately expressed by the peptidergic than nonpeptidergic nociceptors, and these neurochemical discrepancies provided the basis of the distinct pathways of thermal analgesia and mechanical allodynia. The depletion of peptidergic nociceptors and their IENFs cause thermal analgesia and sensitized nonpeptidergic nociceptors respond to mechanical allodynia. These distinct pathways of noxious stimuli suggested determined by the neurochemical-dependent neurotrophin cognate receptors such as TrkA and Ret receptors. The neurogenic inflammation after TRPV1 depletion also sensitized Ret receptors which results in mechanical allodynia. The activation of spinal TRPV1(+) neurons may contribute to mechanical allodynia. Also, an imbalance in adenosinergic analgesic signaling in sensory neurons such as the downregulation of prostatic acid phosphatase and adenosine A1 receptors, which colocalized with TRPV1 as a membrane microdomain also correlated with the development of mechanical allodynia. Collectively, TRPV1 depletion-induced mechanical allodynia involves a complicated cascade of cellular signaling alterations.
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Affiliation(s)
- Chin-Hong Chang
- Department of Surgery, Chi Mei Medical Center, Tainan, Taiwan
| | - Ying-Shuang Chang
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Lin Hsieh
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- School of Post-Baccalaureate Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
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Solinski HJ, Rukwied R. Electrically Evoked Itch in Human Subjects. Front Med (Lausanne) 2021; 7:627617. [PMID: 33553220 PMCID: PMC7855585 DOI: 10.3389/fmed.2020.627617] [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: 11/09/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
Administration of chemicals (pruritogens) into the skin evokes itch based on signal transduction mechanisms that generate action potentials mainly in mechanically sensitive and insensitive primary afferent C-fibers (pruriceptors). These signals from peripheral neurons are processed in spinal and supra-spinal centers of the central nervous system and finally generate the sensation of itch. Compared to chemical stimulation, electrical activation of pruriceptors would allow for better temporal control and thereby a more direct functional assessment of their activation. Here, we review the electrical stimulation paradigms which were used to evoke itch in humans in the past. We further evaluate recent attempts to explore electrically induced itch in atopic dermatitis patients. Possible mechanisms underlying successful pruritus generation in chronic itch patients by transdermal slowly depolarizing electrical stimulation are discussed.
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Affiliation(s)
- Hans Jürgen Solinski
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Roman Rukwied
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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