Neuropathic Itch

Enhanced CXCL10 expression in mast cells for cutaneous neurofibroma presenting with pain and itch

BACKGROUND

Cutaneous neurofibroma (cNF) presenting with pain and itch substantially affects the quality of life. The CXCL10/CXCR3 axis, a well-known chemokine signaling pathway involved in pain and itch transmission, has recently been implicated in neurofibroma development. Our study aims to investigate the expression patterns and potential roles of the CXCL10/CXCR3 axis in pain and itch associated with cNFs.

METHODS

We examined the expression of CXCL10/CXCR3 and immune cell profiles in 53 human solitary cNFs through immunohistochemical staining. The Chinese version of the Short-form McGill Pain Questionnaire and the Chinese Eppendorf Itch Questionnaire were used to assess pain and itch symptoms of cNF tumors, respectively.

RESULTS

Elevated expression of CXCL10/CXCR3 was observed in tumoral and dermal parts of symptomatic cNFs. The percentage of mast cells expressing CXCL10, but not CXCR3, was significantly higher in symptomatic cNFs compared to asymptomatic cNFs (51.18% vs. 19.07%, respectively, p < 0.0001). The symptomatic cNFs exhibited significantly higher intraepidermal nerve fiber density compared to asymptomatic cNFs (p = 0.009).

CONCLUSIONS

Our study suggests that CXCL10, potentially mediated by mast cells, may contribute to sensory dysfunction in cNF and may be a target for treating the pain and itch symptoms associated with cNFs. Our study suggests a model in which the CXCL10/CXCR3 pathway plays a role in inducing pain and itch in cNFs, potentially through mast cell mediation. Mast cells may increase the secretion of CXCL10, thereby contributing to pain and itch in cNF, making them a potential target for treating these symptoms. Created in BioRender. Pham, Q. (2025) https://BioRender.com/i89y356 .

Patient perspective on symptoms of Notalgia paresthetica: subpopulation results from the Neuropathic Itch Patient Survey (NIRVE)

Background: Notalgia paresthetica (NP) is a form of neuropathic itch characterized by recurrent itch in the mid back. Much about NP remains unclear, especially the patient experience.

Objectives: The Neuropathic Itch Patient Survey (NIRVE) was a global, online survey conducted to better characterize the symptom burden of neuropathic itch from the patient perspective.

Patients and methods: This report focuses on the symptom burden of the subpopulation of NIRVE participants with a self-reported diagnosis of NP (N = 91). Respondents reported visiting a median of 2 healthcare providers (HCPs) for their symptoms before receiving an accurate diagnosis of NP.

Results: The most common cutaneous symptoms ever experienced were itch/pruritus, sensitive skin, painful or raw skin, numbness, and tingling. The symptoms reported by the most respondents as currently being experienced included itch/pruritus, numbness, painful or raw skin, tingling, and burning or hot sensation. Of patients currently experiencing symptoms, numbness and itch/pruritus were ranked as the most intense, followed by tingling, burning or hot sensation, and then painful or raw skin. Most patients consult multiple healthcare providers (HCPs) before receiving a diagnosis for their condition.

Conclusion: Itch is overwhelmingly the most prevalent symptom of the condition, although half of patients also report experiencing sensitive skin, painful or raw skin, numbness, or tingling.

Chronic Pruritus Alleviation in the Elderly Through Drug-Free Autophagy Activation by Magnetized Saline Water: A Case Series

Chronic pruritus is a common and distressing condition in the elderly population, frequently associated with various underlying systemic diseases and age-related skin changes. Conventional treatments, such as emollients and moisturizers, may not invariably provide adequate relief. Magnetized saline water has previously been shown to activate autophagy, a cellular process involved in maintaining skin barrier function, reducing inflammaging, and modulating neuropathic pain. This case series investigated the efficacy of a topical serum containing magnetized saline water in managing chronic pruritus with diverse etiologies in elderly patients. Five patients aged 69-80 years, presenting with chronic pruritus lasting two to six months, were instructed to apply the serum daily to the most affected areas for a minimum of 14 consecutive days. Pruritus severity was assessed using the 12-Item Pruritus Severity Scale (12-PSS) at baseline and post-intervention. The underlying causes of pruritus included end-stage renal disease, type 2 diabetes mellitus with peripheral neuropathy, advanced liver fibrosis, and xerosis cutis. All five patients reported a substantial improvement in pruritus severity following the application of the magnetized saline water serum, with post-intervention 12-PSS scores decreasing by 3-5 points. The serum was well-tolerated, and no adverse effects were reported. These findings suggest that topical formulations containing magnetized saline water may be a promising alternative or adjunctive therapy for managing chronic pruritus in the elderly population. However, clinical trials are needed to confirm these findings, elucidate the precise mechanisms of action, and establish optimal treatment protocols.

The COL6A5-p.Glu2272* mutation induces chronic itch in mice

Pruritus is a common irritating sensation that provokes the desire to scratch. Environmental and genetic factors contribute to the onset of pruritus. Moreover, itch can become a major burden when it becomes chronic. Interestingly, the rare Collagen VI alpha 5 (COL6A5) gene variant p.Glu2272* has been identified in two families and an independent patient with chronic neuropathic itch. These patients showed reduced COL6A5 expression in skin and normal skin morphology. However, little progress has been made until now toward understanding the relationships between this mutation and chronic itch. Therefore, we developed the first mouse model that recapitulates COL6A5-p.Glu2272* mutation using the CRISPR-Cas technology and characterized this new mouse model. The mutant mRNA, measured by RT-ddPCR, was expressed at normal levels in dorsal root ganglia and was decreased in skin. The functional exploration showed effects of the mutation with some sex dysmorphology. Mutant mice had increased skin permeability. Elevated spontaneous scratching and grooming was detected in male and female mutants, with increased anxiety-like behavior in female mutants. These results suggest that the COL6A5-p.Glu2272* mutation found in patients contributes to chronic itch and induces in mice additional behavioral changes. The COL6A5-p.Glu2272* mouse model could elucidate the pathophysiological mechanisms underlying COL6A5 role in itch and help identify potential new therapeutic targets.

Alleviation of neuropathic pain with neuropeptide Y requires spinal Npy1r interneurons that coexpress Grp

Neuropeptide Y targets the Y1 receptor (Y1) in the spinal dorsal horn (DH) to produce endogenous and exogenous analgesia. DH interneurons that express Y1 (Y1-INs; encoded by Npy1r) are necessary and sufficient for neuropathic hypersensitivity after peripheral nerve injury. However, as Y1-INs are heterogenous in composition in terms of morphology, neurophysiological characteristics, and gene expression, we hypothesized that a more precisely defined subpopulation mediates neuropathic hypersensitivity. Using fluorescence in situ hybridization, we found that Y1-INs segregate into 3 largely nonoverlapping subpopulations defined by the coexpression of Npy1r with gastrin-releasing peptide (Grp/Npy1r), neuropeptide FF (Npff/Npy1r), and cholecystokinin (Cck/Npy1r) in the superficial DH of mice, nonhuman primates, and humans. Next, we analyzed the functional significance of Grp/Npy1r, Npff/Npy1r, and Cck/Npy1r INs to neuropathic pain using a mouse model of peripheral nerve injury. We found that chemogenetic inhibition of Npff/Npy1r-INs did not change the behavioral signs of neuropathic pain. Further, inhibition of Y1-INs with an intrathecal Y1 agonist, [Leu31, Pro34]-NPY, reduced neuropathic hypersensitivity in mice with conditional deletion of Npy1r from CCK-INs and NPFF-INs but not from GRP-INs. We conclude that Grp/Npy1r-INs are conserved in higher order mammalian species and represent a promising and precise pharmacotherapeutic target for the treatment of neuropathic pain.

Management of Brachioradial Pruritus With Cervical Epidural Steroid Injection: A Case Report

Brachioradial pruritus (BRP) is a neuropathic dysesthesia described as itching over the dorsolateral forearm. The etiology of BRP has not been fully identified but is hypothesized to be multifactorial, including sun exposure and cervical spine disease. Management of BRP is challenging, and conservative measures often fail to provide notable improvement. We present a case of a 71-year-old woman with BRP refractory to topical and oral treatment, with radiographic evidence of cervical spinal canal and neuroforaminal stenosis. Two rounds of cervical epidural steroid injections (CESI) were performed at the C6-C7 epidural space resulting in a marked improvement of symptoms. With this case report, we would like to add to the current scientific knowledge of BRP management and the potential utilization of CESIs to provide symptomatic relief to patients suffering from refractory pruritus.

Druggable Targets and Compounds with Both Antinociceptive and Antipruritic Effects

Pain and itch are both important manifestations of various disorders, such as herpes zoster, atopic dermatitis, and psoriasis. Growing evidence suggests that both sensations have shared mediators, overlapping neural circuitry, and similarities in sensitization processes. In fact, pain and itch coexist in some disorders. Determining pharmaceutical agents and targets for treating pain and itch concurrently is of scientific and clinical relevance. Here we review the neurobiology of pain and itch and discuss the pharmaceutical targets as well as novel compounds effective for the concurrent treatment of these sensations.

Satellite Glial Cells and Neurons in Trigeminal Ganglia Are Altered in an Itch Model in Mice

Itch (pruritus) is a common chronic condition with a lifetime prevalence of over 20%. The mechanisms underlying itch are poorly understood, and its therapy is difficult. There is recent evidence that following nerve injury or inflammation, intercellular communications in sensory ganglia are augmented, which may lead to abnormal neuronal activity, and hence to pain, but there is no information whether such changes take place in an itch model. We studied changes in neurons and satellite glial cells (SGCs) in trigeminal ganglia in an itch model in mice using repeated applications of 2,4,6-trinitro-1-chlorobenzene (TNCB) to the external ear over a period of 11 days. Treated mice showed augmented scratching behavior as compared with controls during the application period and for several days afterwards. Immunostaining for the activation marker glial fibrillary acidic protein in SGCs was greater by about 35% after TNCB application, and gap junction-mediated coupling between neurons increased from about 2% to 13%. The injection of gap junction blockers reduced scratching behavior, suggesting that gap junctions contribute to itch. Calcium imaging studies showed increased responses of SGCs to the pain (and presumed itch) mediator ATP. We conclude that changes in both neurons and SGCs in sensory ganglia may play a role in itch.

Association between chronic idiopathic cough and sensitive skin syndromes is a new argument in favor of common neuropathic pathways: results from a survey on 4050 subjects

Sensitive skin syndrome has a neuropathic origin, which is why it is frequently associated with irritable bowel syndrome. We have looked for a possible association with chronic cough, which is commonly maintained by neurogenic mechanisms, whatever the initial cause(s). A survey was carried out on a representative sample of the population over 15 years of age using the quota method. The questionnaire included sociodemographic data and questions about sensitive skin, the presence of chronic cough, smoking and possible causes of chronic cough. Chronic cough was assessed by the Leicester Cough Questionnaire, and 4050 subjects responded (mean age: 45 years). Overall, 12.2% of subjects with a chronic cough were compared to the 87.8% without any cough. Among them, 72.5% had sensitive skin (vs. 47.8%, p < 0.001); additionally, 17.4% of the subjects with sensitive skin had a chronic cough (vs. 6.9% if no sensitive skin). These proportions were higher if very sensitive skin was reported. The risk of having chronic cough was twice as high if sensitive skin was reported [OR = 1.9 (1.5-2.4), p < 0.001]. The risk of having sensitive skin was also twice as high for chronic cough. Thus, chronic cough and sensitive skin are frequently associated. This association represents a new argument in favor of a neuropathic nature of sensitive skin. Sensitive skin and chronic cough are both modes of overreaction to environmental factors, which tend to be autonomized by neurogenic mechanisms. Dermatologists should ask their patients if they have a chronic cough, and pneumologists should ask about the presence of sensitive skin.

Mas-related G protein-coupled receptors (Mrgprs) - Key regulators of neuroimmune interactions

Interplay between physiological systems in the body plays a prominent role in health and disease. At the cellular level, such interplay is orchestrated through the binding of specific ligands to their receptors expressed on cell surface. G protein-coupled receptors (GPCR) are seven-transmembrane domain receptors that initiate various cellular responses and regulate homeostasis. In this review, we focus on particular GPCRs named Mas-related G protein-coupled receptors (Mrgprs) mainly expressed by sensory neurons and specialized immune cells. We describe the different subfamilies of Mrgprs and their specific ligands, as well as recent advances in the field that illustrate the role played by these receptors in neuro-immune biological processes, including itch, pain and inflammation in diverse organs.