Clinical Classification of Itch: a Position Paper of the International Forum for the Study of Itch

[Recommended diagnostics for pruritus affecting primary non-lesional skin]

BACKGROUND

Chronic pruritus affecting primary non-lesional skin (CPNL) manifests as a common symptom across a spectrum of diseases spanning various medical specialties. Given the diverse etiological factors involved, diagnosing the underlying condition poses a significant challenge.

OBJECTIVES

To provide a comprehensive overview of clinical, laboratory, and imaging diagnostics for CPNL.

MATERIALS AND METHODS

A thorough literature search on the diagnostics of chronic pruritus was conducted using PubMed with specific keywords "chronic pruritus AND non-lesional skin", "chronic itch AND non-lesional skin", "chronic pruritus AND diagnostics", "chronic itch AND diagnostics", "CKD-aP", "hepatic pruritus", "cholestatic pruritus", and "myeloproliferative neoplasms AND pruritus".

RESULTS

A systematic diagnostic approach is recommended for patients with CPNL, guided by the prevalence of pruritus-associated diseases. Initial basic diagnostics facilitate a cost-effective and focused evaluation during the initial medical assessment. Information pertaining to underlying diseases can be further refined through specialized diagnostic procedures.

CONCLUSIONS

CPNL often presents a diagnostic dilemma. Adopting a stepwise diagnostic strategy facilitates the identification of underlying etiologies, which is crucial for recognizing diseases and administering pruritus-specific pharmacotherapy.

[Rehabilitation for patients with chronic pruritus]

BACKGROUND

For a long time, chronic pruritus was considered difficult to treat. Modern therapy options and detailed guidelines have created new opportunities for patients to improve their quality of life. However, due to the complexity of the disease, the need for multimodal treatment remains.

OBJECTIVES

This article aims to investigate whether dermatological rehabilitation offers additional benefits to those affected and whether it should therefore be part of the treatment concept for chronic pruritus.

METHODS

After introduction of the pruritus program of a rehabilitation clinic, a prospective study is presented that focuses on the patient-relevant benefits of therapy. It used standardized questionnaires to record pruritus intensity, the presence of depression, anxiety, itch-related limitations, and quality of life in patients with chronic pruritus before and after rehabilitation.

RESULTS

Of the patients surveyed, 91.7% achieved a patient-relevant benefit through rehabilitation. Pruritus intensity, depression, anxiety, itch-related limitations, and restrictions on quality of life decreased significantly. Almost half of all participating patients had been initially diagnosed more than 10 years ago.

CONCLUSIONS

Dermatological rehabilitation with a multimodal concept for the treatment of chronic pruritus can help affected patients and should be part of the therapy concept. This should be done as early as possible before the disease progresses over a long period of time and makes treatment more difficult.

Validation of the German Pruritus Questionnaire for the systematic assessment of chronic pruritus

BACKGROUND

Chronic pruritus is a clinically heterogeneous symptom that manifests itself with varying duration, intensity, or quality. To date, there is no validated German-language instrument that systematically assesses the relevant parameters. With the support of the Pruritus Research Working Group (Arbeitsgemeinschaft Pruritusforschung, AGP), a questionnaire for the assessment of chronic pruritus (AGP questionnaire) was developed in 2008. The subsequently revised instrument, now called the German Pruritus Questionnaire, records pruritus-specific parameters such as localization, course, intensity and quality, anamnestic data on the general state of health, sociodemographic data, quality of life, and coping methods. It is to be validated in the study presented here.

PATIENTS AND METHODS

The questionnaire was used in 366 patients with chronic pruritus of different etiologies from Germany (University Hospitals Heidelberg, Münster, Mainz, Erlangen, Giessen, private practice Bad Bentheim, TU Munich, Wiesbaden Kidney Center), Austria (Graz University Hospital) and Switzerland (Aarau Cantonal Hospital).

RESULTS

The reliability for repeated completion (retest reliability) with regard to localization, first occurrence, and concomitant diseases showed high values for Cohen's kappa (> 0.8). The data on the retest reliability of the pruritus characteristics showed lower values (< 0.7). With regard to the measurability of practically relevant changes (change sensitivity), medium to strong effect sizes were found (0.09-0.19). A statistically significant differentiation of the pruritus etiologies based on the recorded parameters was not possible.

CONCLUSIONS

The German Pruritus Questionnaire allows a comprehensive and structured recording of patient- and clinician-reported, relevant dimensions of chronic pruritus of different etiologies. Further adaptation and development are planned.

[Neuropathy in pruritus medicine : Recommended diagnostics and therapy]

Chronic itch is a frequent and debilitating condition that greatly affects the quality of life of those affected. In a subset of patients, damage to the peripheral or central nervous system constitutes the cause of the itch. Small-fiber neuropathy, nerve compression syndromes, post-herpetic neuralgia, scars and burns are possible conditions affecting the peripheral nervous system potentially causing itch, whereas space-occupying lesions affecting the spinal cord and stroke are examples of conditions that may induce central itch. Neuropathic itch starts on normal appearing skin, is often accompanied by pain sensations and other dysesthesias, and usually relieved by local cold application. Its distribution depends on the affected site of the somatosensory system. A comprehensive medical history is paramount to reach the diagnosis, while complementary diagnostics with skin biopsies for the investigation of cutaneous neuromorphological alterations or medical imaging to rule out nerve impingement may be advised in selected cases. Topical agents such as capsaicin or local anesthetics as well as systemic drugs such as gabapentinoids, antidepressants and opioid receptor modulators are used in the treatment of neuropathic itch. This review article provides an overview of the clinical features, underlying causes, diagnostic workup and therapeutic approach in neuropathic itch.

EADV Task Force Pruritus White Paper on chronic pruritus and chronic prurigo: Current challenges and future solutions

Chronic pruritus (CP) is frequent in general medicine and the most common complaint in general dermatology. The prevalence of CP is expected to rise in the future due to the ageing population. The clinical presentation, underlying aetiology and treatment strategy of CP are heterogeneous. Also, individual treatment aims and physical, psychic and economic burdens of patients might vary. Chronic prurigo (CPG) is the most severe disease in the chronic pruritus spectrum, being associated with long-standing scratch-induced skin lesions and a therapy refractory itch-scratch-cycle. It is thus important to raise disease awareness for CP and CPG in the general public and among decision-makers in the health system. Further, there is a need to support a rational clinical framework to optimize both diagnostics and therapeutics. Currently, there is still a shortcoming regarding approved therapies and understanding CP/CPG as severe medical conditions. Therefore, the EADV Task Force Pruritus decided to publish this white paper based on several consensus meetings. The group consented on the following goals: (a) ensure that CP is recognized as a serious condition, (b) increase public awareness and understanding of CP and CPG as chronic and burdensome diseases that can greatly affect a person's quality of life, (c) clarify that in most cases CP and CPG are non-communicable and not caused by a psychiatric disease, (d) improve the support and treatment given to patients with CP to help them manage their disease and (e) publicize existing therapies including current guidelines. We aim to point to necessary improvements in access and quality of care directed to decision-makers in health policy, among payers and administrations as well as in practical care.

Acne excoriée: Diagnostic overview and management

Acne excoriée (AE) is a skin picking disorder (SPD) within the group of obsessive compulsive (OCD) and related disorders characterized by the compulsive manipulation of acne lesions. AE typically appears in females during adolescence or young adulthood and can cause significant disfigurement and psychosocial impairment. This disorder is under-recognized due to patient discomfort to disclose excoriation habits or lack of behavior awareness. It is imperative that dermatologists accurately diagnose and treat this disorder to minimize long-term damage to the skin. This review aims to provide an overview of the diagnosis and treatment options for AE.

Dermatological patients with itch report more stress, stigmatization experience, anxiety and depression compared to patients without itch: Results from a European multi-centre study

BACKGROUND

Itch as the most common symptom in dermatology has been shown to be related to psychological factors such as stress, anxiety and depression. Moreover, associations were found between perceived stigmatization and itch. However, studies investigating the differences between patients with dermatoses with and without itch regarding perceived stress, stigmatization, anxiety and depression are missing. Therefore, one of the aims of the second study of the European Society for Dermatology and Psychiatry (ESDaP study II) was to investigate these relationships in a large cohort of patients with different itchy dermatoses.

RESULTS

3399 patients with 14 different itchy dermatoses were recruited at 22 centres in 17 European countries. They filled in questionnaires to assess perceived stigmatization, stress, signs of clinically relevant anxiety or depression, itch-related quality of life, the overall health status, itch duration, frequency and intensity. The most significant association between the severity of itching and the perception of stress was observed among individuals with rosacea (correlation coefficient r = 0.314). Similarly, the strongest links between itch intensity and experiences of stigmatization, anxiety, and depression were found in patients with seborrheic dermatitis (correlation coefficients r = 0.317, r = 0.356, and r = 0.400, respectively). Utilizing a stepwise linear regression analysis, it was determined that within the entire patient cohort, 9.3% of the variation in itch intensity could be accounted for by factors including gender, levels of anxiety, depression, and perceived stigmatization. Females and individuals with elevated anxiety, depression, and perceived stigmatization scores reported more pronounced itch intensities compared to those with contrary attributes.

CONCLUSION

This study underscores the connection between experiencing itch and its intensity and the psychological strain it places on individuals. Consequently, psychological interventions should encompass both addressing the itch itself and the interconnected psychological factors. In specific cases, it becomes imperative for dermatologists to direct individuals towards suitable healthcare resources to undergo further psychological assessment.

HIV: Inflammatory dermatoses

Patients living with HIV may experience a variety of inflammatory dermatoses, ranging from exacerbations of underlying conditions to those triggered by HIV infection itself. This article presents a current literature review on the etiology, diagnosis and management of atopic dermatitis, psoriasis, pityriasis rubra pilaris, lichen planus, seborrheic dermatitis, eosinophilic folliculitis, pruritic papular eruption and pruritus, in patients living with HIV.

The G protein-coupled estrogen receptor of the trigeminal ganglion regulates acute and chronic itch in mice

AIMS

Itch is an unpleasant sensation that severely impacts the patient's quality of life. Recent studies revealed that the G protein-coupled estrogen receptor (GPER) may play a crucial role in the regulation of pain and itch perception. However, the contribution of the GPER in primary sensory neurons to the regulation of itch perception remains elusive. This study aimed to investigate whether and how the GPER participates in the regulation of itch perception in the trigeminal ganglion (TG).

METHODS AND RESULTS

Immunofluorescence staining results showed that GPER-positive (GPER+ ) neurons of the TG were activated in both acute and chronic itch. Behavioral data indicated that the chemogenetic activation of GPER+ neurons of the TG of Gper-Cre mice abrogated scratching behaviors evoked by acute and chronic itch. Conversely, the chemogenetic inhibition of GPER+ neurons resulted in increased itch responses. Furthermore, the GPER expression and function were both upregulated in the TG of the dry skin-induced chronic itch mouse model. Pharmacological inhibition of GPER (or Gper deficiency) markedly increased acute and chronic itch-related scratching behaviors in mouse. Calcium imaging assays further revealed that Gper deficiency in TG neurons led to a marked increase in the calcium responses evoked by agonists of the transient receptor potential ankyrin A1 (TRPA1) and transient receptor potential vanilloid V1 (TRPV1).

CONCLUSION

Our findings demonstrated that the GPER of TG neurons is involved in the regulation of acute and chronic itch perception, by modulating the function of TRPA1 and TRPV1. This study provides new insights into peripheral itch sensory signal processing mechanisms and offers new targets for future clinical antipruritic therapy.

Site-Specific Transient Receptor Potential Channel Mechanisms and Their Characteristics for Targeted Chronic Itch Treatment

Chronic itch is a debilitating condition with limited treatment options, severely affecting quality of life. The identification of pruriceptors has sparked a growing interest in the therapeutic potential of TRP channels in the context of itch. In this regard, we provided a comprehensive overview of the site-specific expression of TRP channels and their associated functions in response to a range of pruritogens. Although several potent antipruritic compounds that target specific TRP channels have been developed and have demonstrated efficacy in various chronic itch conditions through experimental means, a more thorough understanding of the potential for adverse effects or interactions with other TRP channels or GPCRs is necessary to develop novel and selective therapeutics that target TRP channels for treating chronic itch. This review focuses on the mechanism of itch associated with TRP channels at specific sites, from the skin to the sensory neuron, with the aim of suggesting specific therapeutic targets for treating this condition.

Aetiology, pathogenesis and management of neuropathic itch: A narrative review with recent updates

Neuropathic itch is a relatively common yet under-reported cause of systemic pruritus. It is a debilitating condition often associated with pain, which impairs the patient's quality of life. Although much literature exists about renal and hepatic pruritus, there is a dearth of information and awareness about neuropathic itch. The pathogenesis of neuropathic itch is complex and can result from an insult at any point along the itch pathway, ranging from the peripheral receptors and nerves until the brain. There are several causes of neuropathic itch, many of which do not produce any skin lesions and are thus, often missed. A detailed history and clinical examination are necessary for the diagnosis, while laboratory and radiologic investigations may be needed in select cases. Several therapeutic strategies currently exist involving both non-pharmacological and pharmacological measures, the latter including topical, systemic, and invasive options. Further research is ongoing to clarify its pathogenesis and to design newer targeted therapies with minimal adverse effects. This narrative review highlights the current understanding of this condition, focusing on its causes, pathogenesis, diagnosis, and management, along with newer investigational drugs.

The impact of phototherapy on itch intensity and itch-related quality of life amongst different skin diseases, skin phototypes and genders - A prospective study with 102 patients

BACKGROUND

Phototherapy is a mainstay to treat itchy conditions. However, only little is known about differences in the antipruritic effect of phototherapy amongst different skin conditions, phototypes and genders.

METHODS

In this prospective, single-center study, we analyzed the effect of phototherapy on itch intensity and itch-related quality of life amongst these subgroups after a treatment duration of 4 weeks, while on-demand treatment with topical corticosteroids, topical calcineurin inhibitors and/or antihistamines was allowed.

RESULTS

Of 102 patients (age 53.0 ± 18.7, 56 females [54.9%]), 72 (78.3%) reported a significant reduction of itch intensity by Δ -2.76 on a 0-10 Numerical Rating Scale (NRS), p = <.001, 95% CI [2.2; 3.3] paralleled by a significant improvement of itch-related quality of life as measured by the German version of the ItchyQoL by Δ 7.3, p = <.001, 95% CI [4.4; 11.6]. The best improvement of itch intensity and itch-related QoL was reported by patients with pruritus on non-diseased skin (ΔNRS -3.5; Δ 9.7 Ger-ItchyQoL points), followed by patients with atopic dermatitis and psoriasis. We found no statistical differences in the response to phototherapy amongst Fitzpatrick phototypes I-VI. Women had higher itch intensities at baseline but itch-related quality of life impairment at baseline and phototherapy treatment response did not significantly differ between genders.

CONCLUSION

Phototherapy appears to induce a meaningful itch reduction in various itchy skin conditions, all phototypes and both genders within 4 weeks that directly translates into improvement of itch-related quality of life.

Content validity of the EQ-5D-5L with skin irritation and self-confidence bolt-ons in patients with atopic dermatitis: a qualitative think-aloud study

OBJECTIVES

Two bolt-on dimensions (skin irritation, self-confidence) have been developed for the EQ-5D-5L to improve its content validity and responsiveness in psoriasis. However, the two bolt-ons are not strictly psoriasis-specific and are potentially relevant in other skin conditions. This study aims to explore the content validity of the EQ-5D-5L with two bolt-ons in patients with atopic dermatitis (AD).

METHODS

In 2021-2022, qualitative, semi-structured interviews were conducted with 20 adult AD patients at a university dermatology clinic in Hungary. We aimed for a heterogeneous sample in terms of age, gender, education and disease severity. Patients completed the EQ-5D-5L with two bolt-ons using a think-aloud protocol. Probing questions were posed to investigate item relevance, potential conceptual overlaps, missing concepts and the appropriateness of the recall period. Interview transcripts were subjected to thematic analysis.

RESULTS

The EQ-5D-5L with the two bolt-ons covered the most important aspects of health-related quality of life in AD patients. Most patients found both the skin irritation and self-confidence bolt-ons relevant. Fifteen potential missing concepts were identified, but only two (social relationships, judgement by others) were identified by more than one patient. A smaller conceptual overlap was found between the skin irritation and pain/discomfort dimensions in 7 patients (35%). Half the patients expressed a preference for a recall period of 1 week rather than of 'today'.

CONCLUSIONS

The EQ-5D-5L with skin irritation and self-confidence bolt-ons showed good relevance, comprehensiveness and comprehensibility in patients with AD. However, in terms of comprehensiveness, social relationships and judgement by others (stigma) may be missing from the questionnaire.

Chronic Prurigo Including Prurigo Nodularis: New Insights and Treatments

Chronic prurigo (CPG) is a neuroinflammatory, fibrotic dermatosis that is defined by the presence of chronic pruritus (itch lasting longer than 6 weeks), scratch-associated pruriginous skin lesions and history of repeated scratching. Patients with CPG experience a significant psychological burden and a notable impairment in their quality of life. Chronic prurigo of nodular type (CNPG; synonym: prurigo nodularis) represents the most common subtype of CPG. As CNPG is representative for all CPG subtypes, we refer in this review to both CNPG and CPG. We provide an overview of the clinical characteristics and assessment of CPG, the burden of disease and the underlying pathophysiology including associated therapeutic targets. The information provided results from a PubMed search for the latest publications and a database search for current clinical trials (ClinicalTrials.gov, EU Clinical Trials Register [European Medicines Agency]; using the following terms or combinations of terms: 'chronic prurigo', 'prurigo', 'prurigo nodularis', 'pathophysiology', 'therapy', 'biologics', 'treatment'). Dupilumab is the first authorized systemic therapy by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) for CNPG to date. Topical and systemic agents that are currently under investigation in clinical randomized, placebo-controlled phase II and III trials such as biologics (e.g., nemolizumab, vixarelimab/KPL-716, barzolvolimab/CDX-0159), small molecules (ruxolitinib cream, povorcitinib/INCB054707, abrocitinib) and the opioid modulator nalbuphine are highlighted. In the last past 15 years, several milestones have been reached regarding the disease understanding of CPG such as first transcriptomic analysis, first terminology, first guideline, and first therapy approval in 2022, which contributed to improved medical care of affected patients. The broad range of identified targets, current case observations and initiated trials offers the possibility of more drug approvals in the near future.

Enhancing skin health and safety in aged care (SKINCARE trial): A cluster-randomised pragmatic trial

BACKGROUND

Older nursing home residents are prone to develop different skin conditions at the same time, including xerosis cutis, skin tears, pressure ulcers, incontinence-associated dermatitis or intertrigo. Guidelines and recommendations mainly address these skin conditions separately. The overall aim of this study was to measure the effects of the implementation of a skincare and prevention package.

TRIAL DESIGN

A two-arm cluster-randomised controlled trial was conducted.

METHODS

In nursing homes being assigned to the intervention group, an evidence-based and structured skincare and prevention programme was implemented for six months. Nursing home residents in the control group received standard care as usual. Blinded dermatologists conducted head-to-toe skin assessments, and the researchers assessed skin barrier parameters including stratum corneum hydration and transepidermal water loss at the upper and lower extremities after three and six months. Outcomes included the cumulative incidence of incontinence-associated dermatitis, skin tears, pressure ulcers and intertrigo, and were presented as intention-to-treat and per protocol analysis. Skin dryness and resident-reported outcomes (pain, itch, quality of life) were assessed.

RESULTS

A random sample of 17 nursing homes in the federal state of Berlin, Germany, was drawn and randomised in intervention (n = 9) and control groups (n = 8). In total, 165 participants were allocated to the intervention, and 149 participants were allocated to the control group. The cumulative incidence of skin tears (19.2 %, 95 % CI 12.8-27.8), pressure ulcers (13.6 %, 95 % CI 8.1-21.9) and intertrigo (27.0 %, 95 % CI 18.4-37.7) was lower in the intervention compared to the control group, with cumulative incidences of 27.2 % (95 % CI 19.3-36.9) for skin tears, 16.9 % (95 % CI 10.6-25.9) for pressure ulcer, and 37.8 % (95 % CI 27.5-49.4) for intertrigo. The incidence of incontinence-associated dermatitis was higher in the intervention group (26.3 %, 95 % CI 17.9-36.8) compared to the control group (23.1 %; 95 % CI 14.6-34.5). Mean skin dryness was lower in the intervention group but showed variation. The impact on pain, itch, and quality of life was trivial.

CONCLUSIONS

The present study results indicate that the implementation of tailored and evidence-based nursing routines improves skin health and safety in residential long-term care. Evidence suggests that multiple adverse skin conditions can be prevented by regular skin assessments and individually tailored skincare routines. Positive effects on skin dryness were observed, but skin physiology parameters did not indicate changes of the skin barrier function.

TRIAL REGISTRATION

This study is registered at the German Clinical Trials Register (registration number: DRKS00015680; date of registration: January 29th, 2019) and ClinicalTrials.gov (NCT03824886; date of registration: January 31st, 2019).

A Sensorised Glove to Detect Scratching for Patients with Atopic Dermatitis

In this work, a lightweight compliant glove that detects scratching using data from microtubular stretchable sensors on each finger and an inertial measurement unit (IMU) on the palm through a machine learning model is presented: the SensorIsed Glove for Monitoring Atopic Dermatitis (SIGMA). SIGMA provides the user and clinicians with a quantifiable way of assaying scratch as a proxy to itch. With the quantitative information detailing scratching frequency and duration, the clinicians would be able to better classify the severity of itch and scratching caused by atopic dermatitis (AD) more objectively to optimise treatment for the patients, as opposed to the current subjective methods of assessments that are currently in use in hospitals and research settings. The validation data demonstrated an accuracy of 83% of the scratch prediction algorithm, while a separate 30 min validation trial had an accuracy of 99% in a controlled environment. In a pilot study with children (n = 6), SIGMA accurately detected 94.4% of scratching when the glove was donned. We believe that this simple device will empower dermatologists to more effectively measure and quantify itching and scratching in AD, and guide personalised treatment decisions.

Targeting Transient Receptor Potential (TRP) Channels, Mas-Related G-Protein-Coupled Receptors (Mrgprs), and Protease-Activated Receptors (PARs) to Relieve Itch

Itch (pruritus) is a sensation in the skin that provokes the desire to scratch. The sensation of itch is mediated through a subclass of primary afferent sensory neurons, termed pruriceptors, which express molecular receptors that are activated by itch-evoking ligands. Also expressed in pruriceptors are several types of Transient Receptor Potential (TRP) channels. TRP channels are a diverse class of cation channels that are responsive to various somatosensory stimuli like touch, pain, itch, and temperature. In pruriceptors, TRP channels can be activated through intracellular signaling cascades initiated by pruritogen receptors and underly neuronal activation. In this review, we discuss the role of TRP channels TRPA1, TRPV1, TRPV2, TRPV3, TRPV4, TRPM8, and TRPC3/4 in acute and chronic pruritus. Since these channels often mediate itch in association with pruritogen receptors, we also discuss Mas-related G-protein-coupled receptors (Mrgprs) and protease-activated receptors (PARs). Additionally, we cover the exciting therapeutic targets amongst the TRP family, as well as Mrgprs and PARs for the treatment of pruritus.

[Chronic prurigo]

Chronic prurigo is a very debilitating skin condition characterized by the development of multiple pruriginous nodules, papules or plaques due to a prolonged scratching behavior as a result of chronic itch. Patients often experience anxiety, depression or sleep impairment leading to a substantial decrease in quality of life. Due to the complex pathophysiology and diversity in clinical presentation, managing chronic prurigo remains a challenge. Disease-specific guidelines provide appropriate diagnostic measures and recommend a step-wise therapeutic approach. With the increase of pharmaceutical interest in chronic prurigo, several innovative therapies including monoclonal antibodies and small molecules are currently being investigated for chronic prurigo. This continuing medical education (CME) article provides an overview on various aspects of chronic prurigo, especially on epidemiology, pathophysiology, clinical presentation, diagnostic and therapeutic approach, and innovate therapeutic options.

Serum and Tissue Lipocalin-2 Expression in Chronic Kidney Disease Pruritic Patients

BACKGROUND

Uremic pruritus is an irritating symptom for patients with end-stage kidney disease. Lipocalin-2 (LCN2) has relevant importance in several biological cellular processes and immunity. It is also a major player in the progression of many disorders, such as renal injury.

AIM

To evaluate LCN2 expression in chronic kidney disease (CKD) pruritic patients in serum together with immunohistochemical expression in skin samples and further correlation of their results with the studied clinicopathologic parameters.

MATERIALS AND METHODS

Serum level of LCN2 (assessed by enzyme-linked immunosorbent assay) and skin immunohistochemical expression were investigated in 25 CKD patients and 25 healthy controls. Ten patients were subjected to narrowband ultraviolet B phototherapy for 12 weeks then re-evaluated for serum and tissue LCN2 after therapy.

RESULTS

LCN2 expression was increased significantly in both the epidermis and dermal adnexa in CKD patients over controls. Also, serum LCN2 level was higher in patients than in healthy subjects and was significantly associated with itching severity, grades of CKD, urea, and creatinine serum level. Tissue and serum levels of LCN2 were significantly diminished in CKD patients following narrowband therapy along with improvement of the severity of pruritus.

CONCLUSIONS

The increased serum and tissue LCN2 expression in CKD pruritic patients and its pronounced decrease, in addition to the improvement of pruritus after treatment, suggest a major pathogenic role of LCN2 in uremic pruritus.

Antipruritic effects of geraniol on acute and chronic itch via modulating spinal GABA/GRPR signaling

BACKGROUND AND PURPOSE

Itch (pruritus) is a common unpleasant feeling, often accompanied by the urge of scratching the skin. It is the main symptom of many systemic and skin diseases, which can seriously affect the patient's quality of life. Geraniol (GE; trans-3,7-dimethyl-2,6-octadien-1-ol) is a natural monoterpene with diverse effects, including anti-inflammatory, antioxidant, neuroprotective, anti-nociceptive, and anticancer properties. The study aims to examine the effects of GE on acute and chronic itch, and explore the underlying mechanisms.

METHODS

Acute itch was investigated by using Chloroquine and compound 48/80 induced model, followed by manifestation of diphenylcyclopropenone (DCP)-induced allergic contact dermatitis and the acetone-ether-water (AEW)-induced dry skin model in mice. The scratching behavior, skin thickness, c-Fos expression, and GRPR protein expression in the spinal cord were subsequently monitored and evaluated by behavioral tests as well as pharmacological and pharmacogenetic technologies.

RESULTS

Dose-dependent intraperitoneal injection of GE alleviated the acute itch, induced by chloroquine and compound 48/80, as well as increased the spinal c-Fos expression. Intrathecal administration of GE suppressed the GABAA receptor inhibitor bicuculline-induced itch, GRP-induced itch, and the GABAergic neuron inhibition-induced itch. Furthermore, the subeffective dose of bicuculline blocked the anti-pruritic effect of GE on the chloroquine and compound 48/80 induced acute itch. GE also attenuated DCP and AEW-induced chronic itch, as well as the increase of spinal GRPR expression in DCP mice.

CONCLUSION AND IMPLICATIONS

GE alleviates both acute and chronic itch via modulating the spinal GABA/GRPR signaling in mice. Findings of this study reveal that GE may provide promising therapeutic options for itch management. Also, considering the pivotal role of essential oils in aromatherapy, GE has great application potential in aromatherapy for treating skin diseases, and especially the skin with severe pruritus.

Chronic Kidney Disease-Associated Pruritus and Quality of Life: Learning from Our Patients

Chronic kidney disease-associated pruritus is itching directly related to kidney disease that cannot be explained by any other condition. Despite technological advances in the different aspects of dialysis sessions and the best treatment for chronic kidney disease patients, it is still a common problem in our patients. The many complex physiological mechanisms involved, the different hypotheses made over the years on the aetiology of the condition, and the great clinical variability may partially explain the limited knowledge about this problem and the difficulties in treating it. The presence of all these factors leads to the persistence of unpleasant symptoms, which must affect the disease burden and quality of life of kidney patients. Through the presentation of an illustrative clinical case, the aim of this review article is to highlight the need for adequate diagnosis and an improved approach to all aspects of chronic kidney disease-associated pruritus, in view of the heavy burden of the disease and the huge impact on the patient's quality of life.

Basic mechanisms of itch

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.

Clinical aspects and management of chronic itch

Chronic pruritus (CP) (ie, itch that persists for more than 6 weeks) poses significant challenges to patients' health and quality of life. It is a common reason for visits to dermatologists and general practitioners and can be caused by a range of conditions, including systemic diseases such as chronic kidney disease or liver diseases, malignancies, neuropathic conditions, and dermatoses such as atopic dermatitis. CP often does not develop in parallel with the course of the disease and can become an entity of its own, which must be treated with antipruritic drugs, even if the underlying cause is already under therapy. Depending on the etiology of CP, different pathways in the pathogenesis have been analyzed recently, following which new treatments have been developed and tested in randomized controlled trials. This article discusses the recent results of these studies and highlights how best to manage health care for patients with CP.

Prevalence and Characteristics of Itch and Pain in Patients Suffering from Chronic Hand Eczema

BACKGROUND

Hand eczema (HE) is a frequent chronic inflammatory dermatosis. Itch and pain are considered two of the most common and burdensome symptoms of the disease. Yet, the data related to these symptoms are still limited. The aim of this study was to evaluate characteristics of itch and pain in adults suffering from HE.

METHODS

The study group comprised 100 adult HE patients. An original questionnaire designed by the authors was used to survey the patients. It included questions regarding demographic characteristics such as the duration of the disease, exacerbation count, past diagnostics and treatment, as well as atopic predispositions. Additionally, the itch and pain intensity (numerical rating scale-NRS) during '3 days prior to the study' and the 'entire disease' period was implemented. The clinical assessment of the disease severity was performed according to two specific measurement instruments: Investigator Global Assessment for Chronic Hand Eczema (IGA-CHE) scale and Hand Eczema Severity Index (HECSI). To assess patient quality of life (QoL), the DLQI tool was used and to determine the level of stigmatization and for its impact on patients' life the 6-Item Stigmatization Scale (6-ISS) was employed.

RESULTS

Within the period of 3 days prior to the examination, itch was reported by 81.0% of patients (n = 81), whereas 53.0% (n = 53) of them experienced pain. Both symptoms were reported more frequently in females (itch: p = 0.022; pain: p = 0.033). When sexes were compared, females reached higher scores in both IGA-CHE and HECSI. Itch and pain intensity correlated positively with disease severity. The intensity of itch and pain significantly influences HE patients' QoL. A positive correlation between the 6-ISS score and the intensity of itch in the 'last 3 days' period was revealed (r = 0.221; p = 0.027).

CONCLUSIONS

Itch and pain are common symptoms in HE patients, significantly contributing to the feeling of stigmatization. Providing characteristics of itch and pain may improve HE management. Symptom-decreasing treatment would definitely have a positive influence on patients' well-being.

Prevalence, Intensity and Psychosocial Burden of Acne Itch: Two Different Cohorts Study

BACKGROUND

Chronic itch is a common symptom of inflammatory skin diseases. This study was undertaken to evaluate the presence and intensity of itching in two different cohorts of acne subjects. Additionally, the influence of itching on the psychosocial status of acne individuals was assessed.

METHODS

Consecutive acne patients seeking dermatological advice and university students diagnosed with acne during dermatological screening were considered. The clinical and psychological aspects of acne were assessed using a variety of instruments.

RESULTS

About 40% of acne subjects in both cohorts reported itching. The mean WI-NRS during the last 3 days in acne patients was 3.83 ± 2.31 points (mild itch) and was significantly more severe (p < 0.001) than in university students diagnosed with acne (2.09 ± 1.29 points). Itch intensity did not depend on the clinical severity of acne. In consecutive acne patients, itch intensity correlated with quality-of-life impairments (assessed using DLQI and CADI) and HADS scores. There was no correlation between itch intensity and stigmatization levels.

CONCLUSIONS

Itching seems to be a common phenomenon in acne sufferers. Acne itch significantly influences patients' well-being and should be considered in a holistic approach to acne patients.

Arsenic exposure and pruritus: Evidence from observational, interventional, and mendelian randomization studies

BACKGROUND

Pruritus is identified as an adverse drug reaction to arsenic trioxide, but the association of arsenic exposure with pruritus has not been investigated.

METHODS

A cross-sectional study was conducted in Shimen, China. A Mendelian randomization analysis was conducted to confirm the causal relationship between genetically predicted percentages of monomethylated arsenic (MMA%) and dimethylated arsenic (DMA%) in urine with chronic pruritus in UK Biobank. A case-control study was then conducted to determine the biomarker for pruritus. Arsenite-treated mice were used to confirm the biomarker, and von Frey test was used to induce scratching bouts. Last, a randomized, double-blind, placebo-controlled trial was conducted to test the efficacy of naloxone in arsenic-exposed patients with pruritus in Shimen.

RESULTS

Hair arsenic (μg/g) showed a dose-response relationship with the intensity of itch in 1079 participants, with odds ratios (OR) of 1.11 for moderate-to-severe itch (p = 0.012). The Mendelian randomization analysis confirmed the causal relationship, with ORs of 1.043 for MMA% (p = 0.029) and 0.904 for DMA% (p = 0.077) above versus under median. Serum β-endorphin was identified as a significant biomarker for the intensity of itch (p < 0.001). Consistently, treatment with arsenite upregulated the level of β-endorphin (p = 0.002) and induced scratching bouts (p < 0.001) in mice. The randomized controlled trial in 126 participants showed that treatment with sublingual naloxone significantly relieved the intensity of itch in arsenic-exposed participants in 2 weeks (β = -0.98, p = 0.04).

CONCLUSION

Arsenic exposure is associated with pruritus, and β-endorphin serves as a biomarker of pruritus. Naloxone relieves pruritus in patients with arseniasis.

Clinical and histopathological investigation of symmetrical alopecia with associated chronic pruritus in tufted capuchin monkeys (Sapajus apella apella)

BACKGROUND

Symmetrical alopecia is a common symptom of endocrine and autoimmune diseases, which are rarely manifested with pruritus. Increased levels of stress in primates have been presented with increased levels of pruritus and alopecia appearance.

METHODS

A pruritic and alopecic disease was investigated in a group of tufted capuchin monkeys (N = 12), but due to ethical reasons, four random animals were further investigated by numerous diagnostic methods. The impact of food and enclosure enrichment was assessed and observed over a 2-year period.

RESULTS

Histopathology of four random tufted capuchin monkeys revealed lymphocytic perifolliculitis, with an appearance of a "swarm of bees" which was suggestive of alopecia areata. Etiological classification of pruritus excluded dermatological, systemic, and neurological causes, making it behavioral. Enclosure and food enrichment had a beneficial impact on pruritus (12/12) and alopecia (10/12).

CONCLUSION

The findings were suggestive of alopecia areata, while the pruritus was considered behavioral in origin. Alopecia and pruritus improved upon enclosure and food enrichment.

Therapeutic potential of bromhexine for acute itch in mice: Involvement of TMPRSS2 and kynurenine pathway

Itching is an unpleasant sensation on the skin that could negatively impact the quality of life. Over the years, many non-pharmacological and pharmacological approaches have been introduced to mitigate this burdensome condition; However, the effectiveness of these methods remains questioned. Bromhexine, derived from the Adhatoda vasica plant, is a safe drug with minimal side effects. It has been widely used in managing respiratory symptoms over the years. The results of our study revealed that bromhexine has the potential to alleviate acute itch induced by Compound 48/80, a known mast cell destabilizer. According to our findings, bromhexine exerts its antipruritic effects primarily by inhibiting the Transmembrane Protein Serine Protease 2 (TMPRSS2) and, to a lesser extent, by decreasing the activation of the Kynurenine Pathway (KP). We further investigated the KP involvement by administrating 1-Methyl Tryptophan (1-MT), a known indoleamine-2,3-dioxygenase (IDO) inhibitor. 1-MT was found to be effective in reducing the itch itself. Moreover, co-administration of bromhexine and 1-MT resulted in synergistic antipruritic effects, suggesting that KP plays a role in acute itch. To conclude, we have presented for the first time a repositioning of bromhexine as a treatment for acute itch. In addition, we addressed the involvement of TMPRSS2 and KP in this process.

Chronic kidney disease-associated pruritus in patients undergoing hemodialysis: Xerosis and topical therapy

Chronic kidney disease-associated pruritus (CKD-aP) is a common and distressing symptom for patients with CKD and a difficult challenge for nephrologists and dermatologists. Recent results showed the multifactorial nature of the pathophysiology, and therapeutic trials were only successful in certain subsets of patients. The clinical manifestations are varied, with xerosis being the most common dermatological manifestation and correlated with the intensity of CKD-aP. A better understanding of the pathophysiology of xerosis in CKD-aP and appropriate topical treatment could correct xerosis to reduce the intensity of CKD-aP and improve the patient's quality of life.

Phase 2 Trial of Difelikefalin in Notalgia Paresthetica

BACKGROUND

Notalgia paresthetica is a neuropathic disorder characterized by pruritus in a circumscribed region of the upper back. Difelikefalin, a selective kappa opioid receptor agonist, has shown efficacy in other chronic pruritic conditions and is being investigated for the treatment of notalgia paresthetica.

METHODS

In this phase 2, double-blind, placebo-controlled trial, we randomly assigned, in a 1:1 ratio, patients with moderate-to-severe pruritus caused by notalgia paresthetica to receive 2 mg of oral difelikefalin or placebo twice daily for 8 weeks. The primary outcome was the change from baseline at week 8 in the weekly mean score on the daily Worst Itch Numeric Rating Scale (WI-NRS; scores range from 0 [no itch] to 10 [worst itch imaginable]). The secondary clinical outcomes were itch-related quality-of-life and itch-related sleep measures.

RESULTS

A total of 126 patients were enrolled; 62 patients were assigned to receive difelikefalin, and 63 were assigned to receive placebo. One patient who had been assigned to receive difelikefalin withdrew consent before the first dose and is not included in the main analyses. The mean baseline WI-NRS score was 7.6 (indicating severe itch) in each group. The change from baseline in the weekly mean WI-NRS score at week 8 was -4.0 points in the difelikefalin group and -2.4 points in the placebo group (difference in change, -1.6 points; 95% confidence interval, -2.6 to -0.6; P = 0.001). The results for the secondary outcomes generally did not support those of the primary analysis. Headache, dizziness, constipation, and increased urine output occurred more frequently in the difelikefalin group than in the placebo group.

CONCLUSIONS

Among patients with notalgia paresthetica, oral treatment with difelikefalin resulted in modestly greater reductions in itch intensity scores than placebo over a period of 8 weeks but was associated with adverse events. Larger and longer trials are needed to assess the efficacy and safety of difelikefalin treatment in this disorder. (Funded by Cara Therapeutics; KOMFORT ClinicalTrials.gov number, NCT04706975.).

Evaluation, management and future perspectives of anal pruritus: a narrative review

PURPOSE

The without a time limitation. Most recent search was performed on 1st June 2022.

RESULTS

Thorough history and physical examination are very important in view of multiple possible causes of anal pruritus. Most of the focus during examination is drawn on to the perianal region. A digital rectal examination and an anoscopy are essential. It is necessary aim of this narrative review is to overview the classification, diagnostics, possible treatment options and future perspective of anal pruritus.

METHODS

The search was performed by two authors (AD and MJ) independently in the following electronic databases: PubMed, EMBASE, Web of Science, Cochrane Library, CENTRAL and the Allied and Complementary Medicine Databases (AMED). Search was restricted to English language only to avoid moisture and the use of soaps in the perianal region. Furthermore, the patient should avoid certain foods and increase the intake of fiber. If the symptoms do not resolve, topical steroids, capsaicin (0.006%) and tacrolimus (0.1%) ointments may be used. For intractable cases, intradermal methylene blue injection might give a long-lasting symptom relief.

CONCLUSION

Anal pruritus is a long-term deteriorating quality of life issue. Most of the time it is a symptom with a difficult diagnosis. Thorough history and examination should be performed for the best possible treatment.

[From ocular itching to eye rubbing: a review of the literature]

Ocular itching and eye rubbing are frequent complaints in an ophthalmology practice. Numerous studies address the consequences of eye rubbing, such as keratoconus. However, there are few studies concerning the pathophysiology of itching, its transmission pathways, or its interactions with eye rubbing. Through this literature review, we will address the various clinical, physiological and therapeutic aspects of this pair of symptoms with a variety of ocular consequences. We will then describe the state of the art in itching and scratching in dermatology, in order to draw a parallel between these two vicious cycles. A better understanding of the pathophysiology of ocular itching and eye rubbing, as well as new studies based on dermatological data, might allow more appropriate clinical management of our patients and their symptoms.

Transcriptomic, Epigenomic, and Neuroanatomic Signatures Differ in Chronic Prurigo, Atopic Dermatitis, and Brachioradial Pruritus

Scratching and scratch-induced injuries, including neuroanatomical alterations, are key characteristics of chronic pruritus entities of different origins. The aim of this study was to link gene expression (array hybridization, qPCR) with DNA methylation (array hybridization) and neuroanatomy (PGP9.5 staining) in chronic nodular prurigo (CNPG), atopic dermatitis (AD), brachioradial pruritus (BRP), and matched healthy controls. Specific signatures of gene expression and DNA methylation clearly discriminated pruritic lesional skin from nonpruritic skin in CNPG and from healthy skin of volunteers, respectively. Although intraepidermal nerve fiber density was indiscriminately reduced, the level of epidermal branching, assessed by a semiquantitative pattern analysis, differentiated the entities (CNPG > BRP > AD). Correspondingly, repellent SEMA3A showed the highest expression in AD, whereas axonal growth-promoting nerve GF was most prominent in CNPG and BRP. Overexpression of genes for nerve fiber regeneration (NELL2/NFKB/ARTN) was found in AD and CNPG but not in BRP. Our findings suggest that differential branching patterns rather than mere innervation density separate chronic itch conditions and reflect disease-specific local expression profiles. In pruritic dermatoses (AD and CNPG), nerve injury and subsequent sprouting may primarily result from chronic scratching, whereas genuine neuropathy is expected to underlie BRP.

Do Merkel complexes initiate mechanical itch?

Itch is a common sensation which is amenable to disabling patients' life under pathological and chronic conditions. Shared assertion easily limits itch to chemical itch, without considering mechanical itch and alloknesis, its pathological counterpart. However, in recent years, our understanding of the mechanical itch pathway, particularly in the central nervous system, has been enhanced. In addition, Merkel complexes, conventionally considered as tactile end organs only responsible for light touch perception due to Piezo2 expressed by both Merkel cells and SA1 Aβ-fibres - low threshold mechanical receptors (LTMRs) -, have recently been identified as modulators of mechanical itch. However, the tactile end organs responsible for initiating mechanical itch remain unexplored. The consensus is that some LTMRs, either SA1 Aβ- or A∂- and C-, are cutaneous initiators of mechanical itch, even though they are not self-sufficient to finely detect and encode light mechanical stimuli into sensory perceptions, which depend on the entire hosting tactile end organ. Consequently, to enlighten our understanding of mechanical itch initiation, this article discusses the opportunity to consider Merkel complexes as potential tactile end organs responsible for initiating mechanical itch, under both healthy and pathological conditions. Their unsuspected modulatory abilities indeed show that they are tuned to detect and encode light mechanical stimuli leading to mechanical itch, especially as they host not only SA1 Aβ-LTMRs but also A∂- and C-fibres.

Efficacy and safety of Chinese herbal medicine in the treatment of chronic pruritus: A systematic review and meta-analysis of randomized controlled trials

Background: Chronic pruritus (CP) is a common and aggravating symptom associated with skin and systemic diseases. Although clinical reports suggest that Chinese herbal medicine (CHM) is safe and effective in Chronic pruritus treatment, evidence to prove it is lacking. Therefore, in this review, we evaluated the therapeutic effects and safety of Chinese herbal medicine for the treatment of Chronic pruritus. Methods: Nine databases were searched for relevant randomized controlled trials (RCTs) from the inception of the database to 20 April 2022. The randomized controlled trials that compared the treatment of Chinese herbal medicine or a combination of Chinese herbal medicine and conventional western medicine treatment (WM) with western medicine treatment intervention for patients with Chronic pruritus were selected. We evaluated the effects of treatment with Chinese herbal medicine on the degree of pruritus, the Dermatology Life Quality Index (DLQI) score, response rate, recurrence rate, and incidence of adverse events in patients with Chronic pruritus. The risk of bias in each trial was evaluated using the Cochrane Collaboration tool. The RevMan software (version 5.3) was used for performing meta-analyses to determine the comparative effects. Results: Twenty-four randomized controlled trials were included, compared with placebo, moderate-quality evidence from one study showed that Chinese herbal medicine was associated with reduced visual analogue scale (VAS) (MD: -2.08; 95% CI = -2.34 to -1.82). Compared with western medicine treatment, low-to moderate-quality evidence from 8 studies indicated that Chinese herbal medicine was associated with reduced visual analogue scale, 4 studies indicated that Chinese herbal medicine was associated with reduced Dermatology Life Quality Index (MD = -1.80, 95% CI = -2.98 to -.62), and 7 studies indicated that Chinese herbal medicine was associated with improved Effective rate (RR: 1.26; 95% CI = 1.19-1.34). Compared with combination of Chinese herbal medicine and western medicine treatment, 16 studies indicated that Chinese herbal medicine was associated with reduced visual analogue scale, 4 studies indicated that Chinese herbal medicine was associated with reduced Dermatology Life Quality Index (MD = -2.37, 95% CI = -2.61 to -2.13), and 13 studies indicated that Chinese herbal medicine was associated with improved Effective rate (RR: 1.28; 95% CI = 1.21-1.36). No significant difference in the occurrence of adverse events in using Chinese herbal medicine or western medicine treatment was reported. Conclusion: The efficacy of Chinese herbal medicine used with or without western medicine treatment was better than western medicine treatment in treating chronic pruritus. However, only a few good studies are available regarding Chronic pruritus, and thus, high-quality studies are necessary to validate the conclusions of this study.

Association between Pruritus and Psychosocial Well-being: A Population-based Study among 6,809 Subjects

Pruritus has an extensive impact on functional, social and psychosocial behaviour. The association between pruritus and psychological well-being has mostly been studied among selected patient groups, whereas population-based studies are lacking. The aim of this study was to determine the association between pruritus and insomnia, quality of life, depression and anxiety at the population level in the general population. A cross-sectional population-based study was conducted in 2012 to 2013. Study subjects (n = 6,809) belonging to the Northern Finland Birth Cohort 1966 Study participated in a large follow-up study at the age of 45-47 years. They completed an extensive health questionnaire including questions on pruritus and several previously validated questionnaires regarding symptoms of psychosocial well-being. Pruritus affected 19.9% of the study subjects weekly, being more common in women than in men (p < 0.001). A significant association was found between both localized and generalized pruritus and symptoms of insomnia, depression, anxiety and decreased quality of life. The association was seen even in those with mild psychological symptoms/insomnia, and it affected both sexes. The severity of psychological symptoms increased with increasing frequency of pruritus. In conclusion, pruritus has a multiple effect on psychosocial well-being. Physicians should consider possible psychosocial symptoms in patients with pruritus.

Anti-pruritic effect of isothiocyanates: Potential involvement of toll-like receptor 3 signaling

The innate immune system has an emerging role as a mediator of neuro-immune communication and a therapeutic target for itch. Toll-like receptor 3 (TLR3) plays an important role in itch, as shown in TLR3 knock-out mice. In this study, to evaluate effects of TLR3 inhibitors on histamine-independent itch, we used two kinds of isothiocyanate (ITC). Both phenethyl isothiocyanate (PEITC) and sulforaphane (SFN) inhibited Poly I:C (PIC)-induced signaling in the RAW264.7 cell line. We then investigated the anti-pruritic effect of these compounds on PIC- and chloroquine (CQ)-induced scratching behavior. PEITC and SFN both suppressed PIC-evoked scratching behavior in mice, and PEITC also inhibited CQ-induced acute itch. Finally, we examined the oxazolone-induced chronic itch model in mice. Surprisingly, oral dosing of both compounds suppressed scratching behaviors that were observed in mice. Our findings demonstrate that TLR3 is a critical mediator in acute and chronic itch transduction in mice and may be a promising therapeutic target for pruritus in human skin disorders. It is noteworthy that SFN has potential for use as an antipruritic as it is a phytochemical that is used as a supplement.

Introduction of a Specific Dermatological Rehabilitation Programme for Patients with Chronic Pruritus: A Pilot Study

Chronic pruritus is a common symptom, associated with several severe medical conditions, great psychological burden, and reduced quality of life. It also poses socio-economic challenges concerning patients' work loss and healthcare costs. In Germany, medical rehabilitation programmes represent an integral part of the medical care of patients with chronic inflammatory skin diseases. However, such programmes play only a rudimentary role in the treatment of other dermatological diseases, such as dermatological oncology, genetic skin diseases, and chronic pruritus. Therefore, a specific antipruritic dermatological rehabilitation programme was developed in cooperation between the Department of Dermatology of the Medical Rehabilitation Center Bad Bentheim and the Center for Chronic Pruritus of the University Hospital of Muenster, Germany. This prospective study compared short-term patient-reported outcomes (n = 121) at the beginning and end of the rehabilitation programme. The majority of subjects had chronic pruritus on primary diseased, inflamed skin. Significant improvements in pruritus intensity (p ≤ 0.001), quality of life (p ≤ 0.001), anxiety symptoms (p ≤ 0.001) and depression (p ≤ 0.001), as well as an overall patient-relevant benefit (Patient Benefit Index 2.6 ± 1.06) and treatment-related patients' satisfaction, were shown. This suggests that implementation of this standardized rehabilitation programme for treatment of patients with chronic pruritus was successful.

Obstacles to Early Diagnosis and Treatment of Pruritus in Patients with Chronic Kidney Disease: Current Perspectives

Chronic kidney disease-associated pruritus (CKD-aP) is a common condition amongst patients with advanced chronic kidney disease (CKD). Several studies have confirmed that more than four out of ten early-stage CKD patients suffer from this condition, while its prevalence among CKD patients on dialysis reaches up to seven out of ten. It is noted to be associated with other disabling symptoms and serious outcomes. It has significant impact on sleep, mood, daily activities, and quality of life of CKD patients, and increased mortality risk of patients on hemodialysis. The Dialysis Outcomes and Practice Patterns Study found 17% higher mortality among patients with moderate to extreme pruritus compared with patients with no or mild pruritus. Despite its high prevalence, ill-effect, and suffering associated with it, CKD-aP remains surprisingly under-reported on the patient's part and under-recognized by the healthcare team. Even upon being noticed, it remains unattended and poorly treated. Its etiopathogenesis is complex and not fully understood. Many treatment options are available but good quality evidence about most of those is absent, and to date, only two medications are approved for use in this condition. While a validated guideline is very much required for the benefit of the patients and caretakers, further research on several aspects of this issue is required.

Complementary and integrative remedies in the treatment of chronic pruritus: A review of clinical trials

BACKGROUND

Chronic pruritus is one of the most common conditions in dermatology and a common manifestation in many systemic diseases. Since the etiology of chronic pruritus remains somewhat unknown, hence, conventional medications may not always show a good therapeutic response. This finding has led both investigators and patients to use herbal and complementary remedies for its treatment. The aim of this study was to review clinical trials in which herbal and complementary medicine was used in the control and treatment of chronic pruritus.

MATERIALS AND METHODS

In this study, we reviewed related articles in this domain, from 2000 to 2020. The search involved electronic databases including PubMed, Scopus, Web of Science, Cochrane, Google Scholar, and SID databases using the keywords "pruritus," "itch," "herb," "complementary medicine," "traditional medicine," "integrative medicine," and their related MeSH terms. Finally, we extracted the pertinent information from these articles and summarized the results.

RESULTS

The findings of this study showed that 17 clinical trials have been conducted till date in order to evaluate the efficacy of herbal remedies and complementary medicines in the treatment of chronic pruritus. Herbal remedies including turmeric, Fumaria parviflora, Avena sativa, capsaicin, sweet almond oil, peppermint oil, violet oil, vinegar, as well as manual therapies including aromatherapy, auricular acupressure, and acupuncture, were significantly effective in the treatment of chronic pruritus.

CONCLUSION

There are only a few studies published on the therapeutic efficacy of herbal remedies and complementary medicine in the treatment of chronic pruritus. Some have shown promising results. Therefore, more evidence-based studies are needed in order to determine if herbal remedies and complementary medicine could be an effective alternative or adjuvant treatment modality in chronic pruritus.

The exploration of the potential mechanism of oxymatrine-mediated antipruritic effect based on network pharmacology and weighted gene co-expression network analysis

The treatment of chronic itch is considered to be a challenge for its non-histamine dependence and the search for alternative medicine is still striving. The pathology of the chronic itch is closely related to immune system regulation and inflammatory response. Oxymatrine (OMT) is a traditional Chinese medicine ingredient extracted from the roots of Sophora flavescens Aiton with significant antitumor, analgesic, and anti-inflammatory effects. However, the underlying mechanism of OMT on chronic itch is obscure, which limits clinical application. Hence, this study is aimed to clarify the pruritus alleviation mechanism of OMT by combining network pharmacology analysis, weighted gene co-expression analysis (WGCNA), and molecular docking. We screened 125 common targets of OMT regulating inflammation and pruritus with pharmacology technology, the GO enrichment function analysis and KEGG signaling pathway analysis to demonstrate the close relation to the signaling pathways regulating inflammation such as MAPK signaling pathway and PI3K-AKT signaling pathway. We adopted the most relevant templates for pruritus diseases, combined with network pharmacology to preliminarily screen out 3 OMT functions and regulatory targets, exerting a good connection and correlation with the target at the screened disease targets. Further experiments were conducted to explore the potential mechanism of OMT using the LPS-induced RAW264.7 cell inflammation model. The results showed that pretreatment with different concentrations of OMT (25 μM, 50 μM, and 100 μM) for 24 h, inhibited expression of IL-6, iNOS TLR4 and TGFR-1 as well as apoptosis of Raw264.7 cells induced by LPS. Moreover, OMT effectively inhibited LPS-induced MAPK pathway activation and the expression of related sites MAP2K1, MAPK8 MAP2K4, and MAPKAP-K2 in RAW 264.7 cells. The OMT also reduced the phosphorylation of p-38, associated with site in the activation of MAPK signaling pathway. These results could contribute to a better understanding of the mechanisms underlying how OMT alleviates inflammation to treat chronic pruritic diseases and provide a potential drug for the treatment of chronic itch.

Inhibitory effects of antibiotic-induced gut microbiota depletion on acute itch behavior in mice

BACKGROUND

The gut microbiota is known to be associated with the regulation of many neurological diseases and behaviors, including chronic pain. However, it is unclear whether the gut microbiota is critical to the itch sensation. In this study, we investigated the effects of gut microbiota depletion on acute itch.

METHODS

First, an antibiotic cocktail was orally administered to deplete the gut microbiota in male C57BL/6 mice. Then, pruritogens were intradermally injected to induce acute itch behavior. In addition, antibiotic-treated mice received transplantation of fecal microbiota from untreated mice, followed by tests for acute itch. The changes in c-Fos expression in trigeminal ganglia (TG) neurons were also investigated by immunofluorescence staining.

RESULTS

Our results indicated that chronic antibiotic treatment significantly reduced the diversity and richness of the gut microbiota of mice. Compared to vehicle-treated mice, antibiotic-treated mice showed reductions in acute itch behavior induced by compound 48/80, chloroquine (CQ), and serotonin (5-HT), respectively. Moreover, repositioning of microbiota reversed the reductions in acute itch behavior in antibiotic-treated mice. In addition, immunofluorescence staining revealed that antibiotic-treated mice displayed decreased c-Fos expression in ipsilateral TG compared to controls.

CONCLUSIONS

Our study, for the first time, discovered that antibiotic-induced gut microbiota depletion could reduce acute itch behavior, which may be connected with decreased TG neuronal activity.

Pruritus in Chronic Kidney Disease: An Update

Chronic kidney disease-associated pruritus (CKDaP) is an often under-diagnosed and under-recognized condition, despite its considerable prevalence within the chronic kidney disease (CKD) population. Universally accepted guidelines are also lacking. The true prevalence of CKDaP worldwide therefore remains unknown, although its negative impact on mortality and health-related quality of life outcomes is very clear. The pathophysiological mechanisms leading to the onset of CKDaP are only partly understood. CKDaP is currently believed to be caused by a multifactorial process, from local skin changes, metabolic alterations, the development of neuropathy and dysregulation of opioid pathways, and psychological factors. Much work has been carried out towards a more systematic and structured approach to clinical diagnosis. Various tools are now available to assess the severity of CKDaP. Many of these tools require greater validation before they can be incorporated into the guidelines and into routine clinical practice. Further efforts are also needed in order to increase the awareness of clinicians and patients so that they can identify the CKDaP signs and symptoms in a timely manner. Currently established treatment options for CKDaP focus on the prevention of xerosis via topical emollients, the optimization of dialysis management, early referral to kidney transplantation if appropriate, oral antihistamine, and a variety of neuropathic agents. Other novel treatment options include the following: topical analgesics, topical tacrolimus, cannabinoid-containing compounds, antidepressants, oral leukotrienes, opioids, and non-pharmacological alternative therapies (i.e., phototherapy, dietary supplements, acupuncture/acupressure). We provide an updated review on the evidence relating to the epidemiology, the pathophysiology, the clinical assessment and diagnosis, and the management of CKDaP.

Psychologic interventions in patients with the chronic dermatologic itch in atopic dermatitis and psoriasis: A step forward with family constellations seminars

Chronic itch is a complex psychophysiological sensation, which can severely affect the quality of life in patients with atopic dermatitis and psoriasis. Itch depends on the irritation of receptors in the skin and the processing of sensory information in the central nervous system. Severe itch leads to activation and later on to disruption of the stress response, resulting in disorders of skin repair, functional and microstructural changes in the areas of the central nervous system that are responsible for the perception of itch. Psychosocial stress can be an essential factor, activating neurohumoral mechanisms which lead to increased itch and scratch, exacerbating skin damage. Patients with chronic itch often have sleep disorders, increased irritability, and depletion of the nervous system. They are characterized by disrupting social relationships, high incidence of anxiety, depressive disorders, and suicidal tendencies. Psychological methods of intervention can effectively influence various mechanisms in the pathogenesis of itch and scratch and improve social functioning in patients with chronic dermatological itch. In this mini-review, we discuss family constellation seminars as an effective method of psychological intervention that can reduce the intensity of itch, and improve sleep and performance in patients with atopic dermatitis and psoriasis. This method is insufficiently described in previous reviews of psychological interventions in atopic dermatitis and psoriasis patients. The positive impact of family constellations seminars in patients with chronic dermatological itch may be related to reducing stress by improving understanding of the family situation, appropriate management of family secrets, and enhancing interactions with the social environment.

High Serum IL-31 Concentration Is Associated with Itch among Renal Transplant Recipients

Chronic itch (CI) is a common symptom caused by both dermatological and systemic disorders. CI is also a frequent, burdensome symptom among renal transplant recipients (RTR); however, its pathophysiology is not fully understood. The aim of this study was to assess the differences in concentration of IL-31 among itchy RTR. The study was performed on a group of selected 129 RTRs (54 itchy and 75 non-itchy patients). Itch severity was assessed with the use of the numeral rating scale (NRS) and the 4-item itch questionnaire (4IIQ). Every subject had his blood drawn to measure the concentration of IL-31. The results were subsequently compared and correlated. The mean concentration differed significantly between RTR suffering from itch (602.44 ± 534.5 pg/mL), non-itchy RTR (161.49 ± 106.61 pg/mL), and HC (110.33 ± 51.81 pg/mL) (p < 0.001). Post-hoc analysis revealed a statistically significantly increased IL-31 serum concentration in itchy RTR in comparison to the non-itchy RTR group (p < 0.001) and HC (p < 0.001). No significant difference was observed in IL-31 serum levels between non-itchy RTRs and HC. No correlation between IL-31 and itch intensity was found. The results of our study clearly demonstrate the association between IL-31 levels and CI in patients after renal transplantation.

Autoimmune Connective Tissue Diseases-Related Pruritus: Proper Diagnosis and Possible Mechanisms

Pruritus is a well-known bothersome symptom among skin disorders, especially inflammatory skin disorders. Lately, a high prevalence of pruritus in patients with autoimmune connective tissue diseases (ACTDs) has been revealed. Patients with ACTDs may suffer from varying degrees of pruritus, which affect their quality of life. However, it is rarely recognized both by patients and physicians. Meanwhile, pruritus is not only a symptom but is also related to the disease severity of some ACTDs. The pathophysiology of ACTD related pruritus is ambiguous. This review summarizes the features and possible mechanisms of ACTD-related pruritus, which might lead to proper diagnosis and treatment.

Mechanisms and therapeutic targets for neuropathic itch

Neuropathic pruritus conditions arise from structural and/or functional damage of the peripheral or central nervous system. Novel findings of pruritus specific mediators and pathways strengthen the specificity theory of pruritus transmission, however electrophysiological studies suggest that focal activation of nociceptors and distinct discharge patterns of primary afferents also contribute to the development of the sensation of pruritus. A complex interplay between excitatory and inhibitory interneurons at spinal level, non-neuronal cells and descending modulation from upper centers contributes to neuronal sensitization and clinically to the chronicity of pruritus, as well as accompanying phenomena such as alloknesis and hyperknesis. Several topical, systemic and non-pharmacological therapeutic approaches directed at distinct targets are currently available.

Small-fibre Neuropathy in Patients with Type 2 Diabetes Mellitus and its Relationship with Diabetic Itch: Preliminary Results

Abstract is missing (Short communication)