Efficacy of Systemic Treatments of Psoriasis on Pruritus: A Systemic Literature Review and Meta-Analysis

Predicting Factors and Clinical Characteristics of Pruritus in Psoriasis: A Cross-Sectional Survey

Pruritus is an important symptom among patients affected by psoriasis. To date, no general agreement has been established regarding pruritus as a measure of psoriasis severity. This study aims to assess psoriatic pruritis prevalence and characteristics using a comprehensive itch questionnaire. A semi-structured questionnaire consisting of 48 questions was applied to patients diagnosed with psoriasis and admitted to the Dermatology Department of Mures Clinical County Hospital, Romania. A total of 163 patients were enrolled, out of which 115 (70.55%) reported itch. Patients with itch had higher PASI (p = 0.003) and DLQI scores (p < 0.001). The itch was most frequently described as a crawling sensation, mainly located in the lesional skin and aggravated by stress and temperature variation. It had a moderate intensity (6.18 ± 2.46). Emollients were the treatment preferred by most patients in alleviating itch, while biologics exerted a protective effect on itch development (OR = -0.24; p < 0.0001) and negatively correlated with itch intensity (r = -0.23; p < 0.0001). Advanced age, high BMI, and PASI scores were indicators of itch presence, while female gender, high PASI score, and frequent itch episodes indicate highly intense pruritus (≥7 on the VAS). A better understanding of itch and its clinical features will guide physicians toward the best treatment option and would, ultimately, benefit the patient.

Association of pruritus with sleep in patients with psoriasis and chronic spontaneous urticaria: A cross-sectional study

Background

Pruritus is a frequent complaint associated with various inflammatory dermatoses. Sleep is often disturbed because of pruritus but the impact of severity and diurnal pattern of pruritus has not been studied so far.

Objectives

To estimate the prevalence of nocturnal itch (NI) and its association with itch severity, sleep disturbance and quality of life (QoL) compared with non-NI in chronic plaque psoriasis (CPP) and chronic spontaneous urticaria (CSU).

Methods

We performed a cross-sectional study in patients aged ≥18 years with CPP or CSU for at least 6 weeks. A comprehensive in-house questionnaire designed for study formed the basis for categorizing patients into NI and non-NI. Validated instruments like visual analog scale, pruritus grading system, General Sleep Disturbance Scale, and Dermatology life quality index were used to assess itch severity, sleep, and QoL.

Results

A total of 255 patients (CPP: 131; CSU: 124) were included in this study. Prevalence of NI was 43.5% (95% confidence interval: 34.9%-52.4%) in CPP and 29% (95% confidence interval: 21.2%-37.9%) in CSU. NI was strongly associated with higher pruritus grading system scores in CSU and CPP (regression coefficient = 1.5, P =0.004 and regression coefficient = 1.3, P =0.004, respectively), with impaired sleep (OR = 2.97, P = 0.025) in CPP and with itch-affected sleep in CSU. Itch severity was associated with impaired sleep; however, the association was modified by the presence of NI in CSU patients.

Conclusion

Nocturnal itch is prevalent in chronic dermatoses and significant for sleep deficit and impaired QoL. Early screening and management of sleep disturbance among patients presenting with nocturnal itch should be routinely undertaken.

Pretreatment with an Aerosol Foam Containing Calcipotriene and Betamethasone Strongly Improves the Efficacy of Narrow-Band UVB Phototherapy

BACKGROUND

Narrow-band (NB) UVB has been combined with a number of topical treatments. However, there have been no specific data regarding treatment results of a fixed combination of calcipotriene 50 μg/g plus betamethasone 0.5 mg/g aerosol foam (Cal/BD) combined with NB-UVB phototherapy so far.

OBJECTIVES

To assess the efficacy of Cal/BD foam coupled to twice-weekly NB-UVB and whether this combined regimen requires fewer UVB treatments and a lower cumulative UVB dose compared to phototherapy alone.

METHODS

This cross-sectional, prospective, parallel-group study enrolled 187 consecutive moderate-to-severe psoriatic patients who were allocated to two groups in a 1:2 ratio. The overall duration of the treatment cycle was 12 weeks. At baseline and after 2, 4, 8 and 12 weeks, we registered the modified (not considering head lesions) PASI, the number of Cal/BD applications, the NRS score for itching and the adverse effects.

RESULTS

The combined regimen was more effective in clearing psoriasis [final mPASI: 2.1 (0; 8.2) versus 4.4 (0; 19.6); p < 0.01] and reducing itching [(final NRS score for itching: 0 (0; 3) versus 1 (0; 4); p < 0.01]. Fewer exposures [12 (4; 20) versus 24 (8; 24); p < 0.01] and a lower cumulative UVB dose [6.1 (5.4; 9.3) J cm^-2 versus 13.1 (9.8; 19.7) J cm^-2; p < 0.01] were required. A higher number of patients achieved complete clearance [47 (74.6%) versus 58 (46.8%) patients (p < 0.001)]. Both treatments were well tolerated without acute adverse effects.

CONCLUSION

Cal/BD + NB-UVB is a very effective treatment that produces a rapid improvement in clinical lesions and itching and can be considered a valuable alternative to systemic treatments for psoriasis.

Efficacy and Safety of Dimethyl Fumarate in Patients with Moderate-to-Severe Plaque Psoriasis: DIMESKIN-2, a Multicentre Single-Arm Phase IIIb Study

This open-label multicentre trial evaluated the efficacy and safety of oral dimethyl fumarate (DMF) in patients with moderate-to-severe plaque psoriasis in real-life clinical practice over 52 weeks. Disease severity and improvement were assessed using the psoriasis area severity index (PASI), body surface area (BSA) affected, and Physician Global Assessment (PGA). Quality of life (QoL) was assessed using the Dermatology Life Quality Index (DLQI) questionnaire. The visual analogue scale (VAS) was used to quantify pruritus and measure treatment satisfaction. A total of 141 patients were included, being 66.7% male, aged 49.1 ± 14.7 years and with disease duration of 16 ± 12.1 years. After 52 weeks, mean PASI decreased from 15.9 ± 6.8 to 1.5 ± 2 and 87.7%, 56.9% and 24.6% of patients achieved PASI 75/90/100 response, respectively. BSA decreased from 26.5 ± 14.8% to 2.7 ± 3.5% at 52 weeks, and 81.5% of patients had a PGA 0-1. DLQI scores decreased from 9.4 ± 6.4 to 2.1 ± 3.3, and VAS of pruritus decreased from 53 ± 28.4 to 19.1 ± 26.2 at Week 52. VAS for treatment satisfaction was 79.4 ± 29.4 at Week 52. A total of 34.2% of patients had an AE leading to permanent discontinuation. These findings show that DMF can significantly improve indices of disease severity, pruritus and QoL, with high levels of patient satisfaction and similar safety profile to other fumarates.

A comprehensive, tri-national, cross-sectional analysis of characteristics and impact of pruritus in psoriasis

BACKGROUND

Pruritus is prevalent in psoriasis but still many features of pruritus, its response to therapy and its burden in psoriasis remain to be better characterized.

OBJECTIVE

To investigate characteristics and burden of pruritus in an international cohort of patients with psoriasis.

METHODS

This cross-sectional study included a total of 634 patients and 246 controls from Germany, Poland and Russia. Physicians examined and interviewed participants, recording clinical characteristics, such as severity, therapy and localization of psoriatic lesions. Participants filled out self-reported questionnaires including questions on pruritus severity and impact, characteristics, and response to therapy, and quality of life (QoL). Localization patterns of pruritus and skin lesions were visualized using body heat maps.

RESULTS

Most patients (82%) experienced pruritus throughout their disease, and 75% had current pruritus. The majority of patients (64%) perceived pure pruritus, and those who reported additional painful and/or burning sensations (36%) reported overall stronger pruritus. The scalp was the most frequently reported localization of pruritus, even in the absence of skin lesions. Body surface area (BSA) of pruritus was not linked to pruritus intensity, but to BSA of psoriatic lesions (rho = 0.278; P < 0.001). One third of patients (31%) reported impaired sex-life, and 4% had suicidal ideations due to pruritus. In up to one third of patients, psoriasis therapies had little or no effect on pruritus. The only therapeutic option offered to some of these patients were antihistamines, which appeared to be effective in most cases.

CONCLUSION

Pruritus is highly prevalent in psoriasis and is linked to a significant burden. Current psoriasis therapies are frequently insufficient to control pruritus. Managing psoriasis should include the assessment and control of itch. Efficient antipruritic therapies should be developed and be made available for patients with psoriasis.

Cytokines and chemokines modulation of itch

Itch (pruritus) is a common cutaneous symptom widely associated with many skin complaints, and chronic itch can be a severe clinical problem. The onset and perpetuation of itch are linked to cytokines, such as interleukin (IL)-31, IL-4, IL-13, IL-33, thymic stromal lymphopoietin, and tumor necrosis factor-alpha, and chemokines, such as chemokine (C-C motif) ligand 2 and C-X-C motif chemokine ligand 10. This review highlights research that has attempted to determine the attributes of various cytokines and chemokines concerning the development and modulation of itch. Through such research, clinical approaches targeting cytokines and/or chemokines may arise, which may further the development of itch therapeutics.

Major Risk Factors Analysis of Pruritus Complicated by Type 2 Diabetes Mellitus and the Effect of Comprehensive Nursing Intervention

Objective

To observe the main risk factors for pruritic skin evidence complicating type 2 diabetes mellitus (T2DM) and the effectiveness of interventions with comprehensive care measures.

Methods

Two hundred and twenty four patients with T2DM admitted to our hospital from June 2020 to November 2021 were selected and divided into Diabetic pruritus group (DP group, n = 71) and T2DM group (n = 153) according to the patients' complications of pruritus. General information such as gender, age, body mass index (BMI), duration of illness, family history, treatment modalities, other comorbidities, underlying illnesses were collected from all patients. Fasting plasma glucose (FPG), renal function [Serum creatinine (Scr), urea nitrogen (BUN), uric acid (BUA)], lipid levels [total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C)] were measured in all patients on day 2 after admission. Risk factors for pruritus complicating T2DM were identified by single multifactorial analysis. Meanwhile, patients in the DP group were divided into group A (n = 35) and group B (n = 36) using the random number table method. Group A adopted the conventional care mode and group B patients adopted the comprehensive care interventions to compare the care effects [visual analog score (VAS) before and after care, treatment efficiency, care satisfaction rate] of patients in groups A and B; the levels of pruritus mediator indicators [substance P,β-endorphin (β-EP) and γ-interferon (INF-γ)] before and after care.

Results

Risk factors for pruritus in T2DM were age, duration of DM, combined Diabetic peripheral neuropathy (DPN), combined diabetic retinopathy (DR), combined diabetic kidney disease (DKD) and serum FPG levels (P &lt;0.05). Satisfaction rate of nursing care, treatment efficiency, post-care improvement in VAS scores, serum substance P, β-EP and INF-γ levels and other mediators of pruritus were better in Group B with integrated nursing intervention than in group A with conventional care only (P &lt; 0.05).

Conclusion

Pruritus in T2DM is associated with age, duration of DM, combined DPN, combined DR, combined DKD and FPG levels. Comprehensive care according to the above risk factors can effectively relieve patients' clinical symptoms and signs, improve the level of pruritus mediators and patient-care relationship.

Data Mining and Meta-Analysis of Psoriasis Based on Association Rules

Psoriasis is a common chronic and recurrent disease in dermatology, which has a great impact on the physical and mental health of patients. Meta-analysis can evaluate the effectiveness and safety of defubao in the treatment of psoriasis vulgaris. This article observes psoriasis skin lesions treated with topical defubao and the changes in blood vessels under dermoscopy. Considering that the Apriori algorithm and the existing improved algorithm have the problems of ignoring the weight and repeatedly scanning the database, this paper proposes a matrix association rule method based on random forest weighting. This method uses the random forest algorithm to assign weights to each item in the data set, and introduces matrix theory to convert the transaction data set into a matrix form and store it, thereby improving operating efficiency. This article included 11 studies, of which 7 studies used the indicator "Researcher's Overall Assessment" (IGA) to evaluate the efficacy, 5 studies used the "Patient Overall Assessment" (PGA) as the efficacy evaluation index, and Loss Area and Severity Index (PASI) was used as an observation index to evaluate the efficacy. Seven studies conducted safety comparisons. In this paper, IGA and PGA were used as evaluation indicators. The treatment effect of the defubao group was better than the calcipotriol group and the betamethasone group. The differences were statistically significant. The effect of the Fubao treatment for 8 weeks is significantly better than that of 4 weeks and 2 weeks, and the differences are statistically different. Using PASI as the evaluation index, a descriptive study was carried out, and it was found that after 4 weeks of treatment for psoriasis vulgaris, the average PASI reduction rate of patients was higher than that of the calcipotriol group and the betamethasone group. The safety evaluation found that after 8 weeks of treatment, the incidence of adverse events in the defubao group was significantly lower than that in the calcipotriol group.

Childhood Trauma and Psychosocial Stress Affect Treatment Outcome in Patients With Psoriasis Starting a New Treatment Episode

OBJECTIVE

Traumatic childhood experiences and psychosocial stress may predispose the evolvement of somatic diseases. Psoriasis is a multifactorial chronic inflammatory skin disease that often associates with current and past stress. Both may entail pathological alterations in major stress axes and a balance shift in the level of T helper type 1 (Th1) and 2 (Th2) cytokines, affecting the development and course of psoriasis. Until now, it is unclear whether traumatic stress experiences during the childhood or current stress are more frequent in psoriatic compared to skin-healthy individuals, and if they interact with treatment outcome.

METHOD

In a prospective cohort study, the impact of acute and early childhood stress on the course of dermatological treatment were studied in patients with moderate to severe psoriasis (PSO). Patients were examined before (T1) and about 3 months after (T2) the beginning of a new treatment episode. Assessments included clinical outcomes (Psoriasis Area and Severity Index-PASI, Structured Clinical Interview SCID-I) and patient-reported outcomes (PRO) (Childhood Trauma Questionnaire-CTQ, Perceived Stress Scale-PSS, itching/scratching, Dermatology Life Quality Index-DLQI, Hospital Anxiety and Depression Scale, Body Surface Area, Self-Administered PASI).

RESULTS

N = 83 PSO patients (median age 53.7, IQR 37.8, 62.5) and n = 66 skin-healthy control subjects (HC) (median age 51.5, IQR 33.3, 59.2) participated. PSO had higher CTQ physical neglect than HC, as well as higher PRO levels. The positive impact of improved skin on the skin-related quality of life was moderated by the perceived stress. Acute stress at T1 had a positive effect both on the skin severity and the skin-related quality of life. CTQ total closely interacted with baseline psoriasis severity, and was associated with higher improvement from T1 to T2.

CONCLUSION

One might tentatively conclude, that chronic psychosocial stressors like childhood maltreatment may predispose the manifestation of psoriasis. The latter may be amplified by acute psychological stressors. In addition, the present evidence suggests that systemic therapies work well in PSO, with childhood trauma and acute psychosocial stress. Both should therefore be routinely assessed and addressed in PSO.

Roles of calcitonin gene-related peptide in the skin, and other physiological and pathophysiological functions

Skin immunity is regulated by many mediator molecules. One is the neuropeptide calcitonin gene-related peptide (CGRP). CGRP has roles in regulating the function of components of the immune system including T cells, B cells, dendritic cells (DCs), endothelial cells (ECs), and mast cells (MCs).

Herein we discuss actions of CGRP in mediating inflammatory and vascular effects in various cutaneous models and disorders.

•

CGRP can help to recruit immune cells through endothelium-dependent vasodilation.

•

CGRP plays an important role in the pathogenesis of neurogenic inflammation.

•

Functions of many components in the immune system are influenced by CGRP.

•

CGRP regulates various inflammatory processes in human skin by affecting different cell-types.

Significance of interleukin-31 (IL-31) gene polymorphisms and IL-31 serum level in psoriasis in correlation with pruritus

Introduction

Interleukin-31 (IL-31) impact on the development and clinical presentation of psoriasis as well as pruritus has not been widely investigated so far.

Aim

To analyse IL-31 -1066G/A and -2057G/A promoter gene polymorphisms as well as serum IL-31 level and their correlation with severity of psoriasis and pruritus in the population of northern Poland.

Material and methods

The study included 300 psoriasis patients and 186 healthy volunteers. The polymorphisms were analysed using amplified refractory mutation system - polymerase chain reaction (ARMS-PCR) method. Serum levels of IL-31 were measured using the enzyme-linked immunosorbent assay (ELISA) test.

Results

The -1066 AA genotype of the IL-31 gene was statistically more frequent in patients and it increased the risk of psoriasis (OR = 1.80; p = 0.04). The GG genotype as well as G allele of the IL-31 -2057 gene polymorphism were rarely observed in psoriasis and were associated with a decreased risk of the disease (OR = 0.6, p = 0.007 and OR = 0.7, p = 0.01, respectively). Serum levels of IL-31 were significantly elevated in psoriasis patients (p < 0.000001), however, they did not correlate with the studied polymorphic variants of the IL-31 gene, severity of psoriasis, disease onset, presence of psoriatic arthritis and pruritus intensity.

Conclusions

Distinct IL-31 promoter gene polymorphisms may be involved in psoriasis development. It seems that serum concentration of IL-31 may not be a reliable marker of psoriatic pruritus.

[Tridimensional in vitro models of nervous and immune systems in the skin]

The immune system and the sensory nervous system are responsible for perceiving danger under distinct yet complementary forms. In the last few years, neuroimmune interactions have become an important topic of dermatological research for conditions including wound healing, atopic dermatitis and psoriasis. We present here a selection of tridimensional in vitro models that reproduce skin structure and integrate an immune or a sensory function. Future evolutions of such models are expected to greatly contribute in a better understanding of reciprocal influences between sensory nervous system and immune system.

Pruritus in psoriasis and atopic dermatitis: current treatments and new perspectives

Psoriasis and atopic dermatitis (AD) are two common chronic inflammatory skin diseases. Although showing different etiology and clinical manifestations, patients with either disease suffer from low health-related quality of life due to pruritus (dermal itch). Recent studies have revealed that more than 85% of psoriasis patients suffer from pruritus, and it is also the dominating symptom of AD. However, as this is a non-life treating symptom, it was partly neglected for years. In this review, we focus on current findings as well as the impact and potential treatments of pruritus in these two skin diseases. We first distinguish the type of itch based on involved mediators and modulators. This clear delineation between the types of pruritus based on involved receptors and pathways allows for precise treatment. In addition, insights into recent clinical trials aimed to alleviate pruritus by targeting these receptors are presented. We also report about novel advances in combinatorial treatments, dedicated to the type of pruritus linked to a causal disease. Altogether, we suggest that only a focused treatment tailored to the primary disease and the underlying molecular signals will provide fast and sustained relief of pruritus associated with psoriasis or AD.

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Antihistamines-refractory chronic pruritus in psoriatic patients undergoing biologics: aprepitant vs antihistamine double dosage, a real-world data

BACKGROUND

Psoriasis-related pruritus (PRP) in patients under systemic treatment is challenging. The risk to switch anti-psoriatic drugs and to lose response to previous therapy is high, thus dermatologists prefer to add an anti-pruritic agent.

OBJECTIVES

To evaluate the effect of anti-histamines and aprepitant in treating PPR of psoriatic patients undergoing systemic anti-psoriatic therapies.

METHODS

A pilot observational open-label study was performed on responsive psoriatic patients with PPR under treatment. Initial therapy included oral rupatadine (10 mg/day for 30 days). In case of the Epworth Sleepiness Scale (ESS) was above 14, patients were switched to aprepitant (80 mg/day for 7 days), otherwise, rupatadine dosage was increased (20 mg/day for 7 days). Clinical evaluation was performed at the baseline (T0) and after 7 days (T7).

RESULTS

We enrolled 40 patients with PPR, 20 in each group. Age, gender, Psoriatic arthritis (PsA) and the itch - VAS, were matched. At T7, aprepitant displayed higher improvements than rupatadine (itch - VAS = 4 [3-5] vs 8.5 [8-9], p < .01, DLQI = 14 [13-16] vs. 18 [16-21], p < .01 and ESS = 5 [4-7] vs 15 [14-16], p < .01). Doubling the rupatadine dosage from 10 mg to 20 mg/day only slightly improve itch (itch - VAS = 9 [8-10] vs 9 [8-9], p = .03), conversely no modifications in the quality of life (DLQI = 18 [17-20] vs 18 [17-21], p = .73) and increased sleepiness (ESS = 10 [9-11] vs 15 [14-16], p < .01).

CONCLUSIONS

Aprepitant may be a valid alternative in PPR patients with ESS >14 under antihistamines.

The Role of Nociceptive Neurons in the Pathogenesis of Psoriasis

Psoriasis is a chronic inflammatory skin disease. Emerging evidence shows that neurogenic inflammation, induced by nociceptive neurons and T helper 17 cell (Th17) responses, has a fundamental role in maintaining the changes in the immune system due to psoriasis. Nociceptive neurons, specific primary sensory nerves, have a multi-faceted role in detecting noxious stimuli, maintaining homeostasis, and regulating the immunity responses in the skin. Therefore, it is critical to understand the connections and interplay between the nociceptive neurons and the immune system in psoriasis. Here, we review works on the altered innervation that occurs in psoriasis. We examine how these distinct sensory neurons and their signal transducers participate in regulating inflammation. Numerous clinical studies report the dysfunction of nociceptive neurons in psoriasis. We discuss the mechanism behind the inconsistent activation of nociceptive neurons. Moreover, we review how neuropeptides, involved in regulating Th17 responses and the role of nociceptive neurons, regulate immunity in psoriasis. Understanding how nociceptive neurons regulate immune responses enhances our knowledge of the neuroimmunity involved in the pathogenesis of psoriasis and may form the basis for new approaches to treat it.

Functional and anatomical brain connectivity in psoriasis patients and healthy controls: a pilot brain imaging study after exposure to mentally induced itch

BACKGROUND

Despite the prevalence of psoriasis, the processing of itch in psoriasis and its impact on the central nervous system (CNS) remain unclear.

OBJECTIVE

We studied the influence of psoriasis on the CNS using magnetic resonance imaging techniques (fMRI and DTI, respectively) to investigate whether mentally induced itch can modify the functional connectivity or the white matter microstructure of the brain.

METHODS

Fourteen patients with chronic psoriasis and 15 healthy controls were recruited. Itch was mentally induced in subjects by videos showing others scratching themselves.

RESULTS

The observation of functional connectivity during the viewing the video revealed an interconnected network of brain regions that are more strongly coupled in psoriasis patients than in healthy controls. This network links the cerebellum, the thalami, the anteroposterior cingulum, the inferior parietal lobules, the middle temporal poles and the parahippocampal, hippocampal, lingual and supramarginal gyri. We also found connections with the right precuneus and both left insula and superior temporal gyrus. The DTI analysis showed that chronic itch affects the microstructure of white matter, including the anterior thalamic radiations, the superior and inferior longitudinal fasciculi, the corticospinal tracts, the cingulum, the external capsules, the inferior frontal-occipital fasciculi and both minor and major forceps.

CONCLUSION

Our results indicate that there could exist a network which is more interconnected in psoriasis patients. Among two building blocks of this network, the subnetwork encoding the perception and control of itch sensation is more affected than the subnetwork representing mentalizing and empathy. With an approach consisting of measuring microstructural changes at a local level in the brain, we also contradict the findings obtained with global measures which stated that chronic psoriasis cannot alter the anatomy of the brain. This confirms that itchy pathophysiological conditions have similar effects on functional and structural connectivity as those observed in chronic pain.

Safety considerations when using drugs to treat pruritus

Introduction: Treatment for chronic pruritus ranges from use of topical formulations to newer biologic agents. Targeting treatment to the underlying etiology is key in reducing the burden of disease while avoiding systemic or adverse effects.Areas covered: This review details the effective medical treatments used in various etiologies of chronic itch with a focus on the potential adverse effects and safety data available for each.Expert opinion: New drug developments in the areas of neural signaling and immune targeting show great promise for the future of chronic itch treatment. These new therapies broaden the available treatment options but also pose new considerations for safety and adverse effects.

Itch: From mechanism to (novel) therapeutic approaches

Itch is a common sensory experience that is prevalent in patients with inflammatory skin diseases, as well as in those with systemic and neuropathic conditions. In patients with these conditions, itch is often severe and significantly affects quality of life. Itch is encoded by 2 major neuronal pathways: histaminergic (in acute itch) and nonhistaminergic (in chronic itch). In the majority of cases, crosstalk existing between keratinocytes, the immune system, and nonhistaminergic sensory nerves is responsible for the pathophysiology of chronic itch. This review provides an overview of the current understanding of the molecular, neural, and immune mechanisms of itch: beginning in the skin, proceeding to the spinal cord, and eventually ascending to the brain, where itch is processed. A growing understanding of the mechanisms of chronic itch is expanding, as is our pipeline of more targeted topical and systemic therapies. Our therapeutic armamentarium for treating chronic itch has expanded in the last 5 years, with developments of topical and systemic treatments targeting the neural and immune systems.

Is there still a role for UV therapy in itch treatment?

Itching is a frequent and greatly distressing symptom related to many skin and systemic diseases. New insights into the pathophysiology of itchy skin and potentially involved mediators have increased the interest in and development of new treatments that specifically act on targets involved in the transmission and perception of itching. Phototherapy has long been known and used as an effective treatment for various kinds of chronic itching. However, despite its well-known beneficial effects, the mechanisms behind the antipruritic effect of phototherapy are less well-known. In addition, phototherapy requires the use of expensive equipment in dermatology offices, patients must undergo repeated treatments and no large, randomized, controlled trials have yet supported the antipruritic effect of UV. Therefore, phototherapy is rarely recommended as a treatment method for chronic pruritic diseases or only used as a last recourse. However, the wide range of pruritic conditions that can be successfully treated with phototherapy, together with its low acute side effects, extremely low frequency of interactions with other medications, possibilities to combine phototherapy with other treatment modalities and the fact that patients of almost all ages-from childhood to old age, including women during pregnancy or lactation-can be treated make UV therapy advantageous over other treatments of chronic pruritus. Thus, despite the development of new targeted therapies against pruritus, UV therapy is neither outdated nor the 'last recourse', but should be considered early on in the treatment of chronic pruritus.

Signs of chronic itch in the mouse imiquimod model of psoriasiform dermatitis: sex differences and roles of TRPV1 and TRPA1

Plaque psoriasis is a chronic inflammatory skin disease that affects a substantial proportion of the world population. This disorder is characterized by scaly, thick skin, intense ongoing itch, and itch from light touch (such as clothing contacting skin, called “alloknesis”). Imiquimod is a topical treatment for basal cell carcinomas and warts that has been used to create a mouse model of plaque psoriasis. Imiquimod-treated male, but not female, wildtype B6 mice showed significant increases in spontaneous scratching, while both sexes exhibited increased alloknesis, indicative of chronic itch. TRPV1 and TRPA1 knockout (KO) mice all exhibited numeric increases in spontaneous scratching which were significant for TRPV1KO mice and TRPA1KO males. Female TRPV1KO and TRPA1KO mice exhibited imiquimod-induced increases in alloknesis scores that did not significantly differ from wildtypes, while alloknesis scores in imiquimod-treated male TRPV1KO and TRPA1KO mice were significantly lower compared with wildtypes, suggesting that these ion channels are necessary for the development of alloknesis in males but not females in this model. Curiously, none of the groups exhibited any significant overall change in chloroquine-evoked scratching following imiquimod treatment, indicating that hyperknesis does not develop in this mouse model. Overall, the data indicate that there are sex differences in this mouse model of psoriasis, and that TRPV1 and TRPA1 ion channels have a small role in promoting the development of itch sensitization. This contrasts with the far greater role these channels play in the manifestation of skin changes in psoriatic dermatitis.

Pruritus in Autoimmune and Inflammatory Dermatoses

Pruritus in autoimmune and inflammatory dermatoses is a common symptom that can be severe and affect the quality of life of patients. In some diseases, pruritus is related to disorders activity and severity or may occur independent of the disease. Despite the high prevalence, the symptom is still underrated and there are only a few trials investigating the efficacy of drugs for disease-specific pruritus. In this review, the characteristics and possible pathomechanisms of pruritus in various dermatoses like autoimmune bullous diseases, connective tissue diseases as well as autoimmune-associated dermatoses (atopic dermatitis, psoriasis vulgaris) is illustrated. Additionally, studies analyzing the antipruritic treatment are discussed. Summarizing, the prevalence of pruritus in these diseases demonstrates the importance for symptom recognition and the need for an efficient antipruritic therapy.

Itch: an under-recognized problem in psoriasis

Psoriasis has historically been considered a nonpruritic dermatosis, in contrast with atopic dermatitis. Thus, itch has often been underappreciated and overlooked in psoriasis. However, increasing evidence over the past decade has shown that itch can be one of the most prevalent and burdensome symptoms associated with psoriasis, affecting almost every patient to some degree. Itch can involve the entire body, although it predominantly affects the legs, hands, back, body and especially the scalp. Uncontrolled itch can significantly impact all aspects of the well-being and quality of life of the patient. While there has been some progress in trying to better understand the pathophysiology of itch in psoriasis, more research effort and interest are needed. This under-recognition of itch in psoriasis is clearly reflected in the dearth of treatment options targeting itch despite significant advancement in treating the lesions themselves. Recently, however, clinical studies have begun to include itch as a study outcome. The resulting data have demonstrated concomitant antipruritic benefits and improved Psoriasis Area and Severity Index (PASI) scores with mainstay treatments for psoriasis, such as topical corticosteroids and vitamin D analogs, phototherapies, and various systemics and biologics. This article takes a closer look at this debilitating symptom, reviewing the available epidemiology data for psoriatic itch, presenting the current understanding of psoriatic itch pathophysiology and highlighting important clinical data for various treatment options for itch. Practical considerations for increasing the recognition of itch as well as improving its management in psoriasis are also provided.

The Antipruritic Effect of Phototherapy

Phototherapy is widely used to treat inflammatory skin diseases such as psoriasis and atopic dermatitis. Repeated suberythemogenic doses of UV-light reduce inflammation in these diseases and ultimately may lead to a complete disappearance of cutaneous symptoms for weeks or months. Chronic pruritus is an important and highly distressing symptom of many of these inflammatory skin diseases. Interestingly, pruritus is also reduced or completely abolished by UV-treatment of psoriasis and atopic dermatitis, and sometimes reduction of pruritus is the first indication for skin improvement by phototherapy. The cutaneous nervous system is an integral part of skin anatomy, and free nerve endings of sensory cutaneous nerve fibers reach up into the epidermis getting in close contact with epidermal cells and mediators from epidermal cells released into the intercellular space. Stimulation of “pruriceptors” within this group of sensory nerve fibers generates a neuronal signal eventually transmitted via the dorsal root and the spinal cord to the brain, where it is recognized as “itch”. UV-light may directly affect cutaneous sensory nerve fibers or, via the release of mediators from cells within the skin, indirectly modulate their function as well as the transmission of itch to the central nervous system inducing the clinically recognized antipruritic effect of phototherapy.

Sensory nerves mediate spontaneous behaviors in addition to inflammation in a murine model of psoriasis

Psoriasis is characterized by keratinocyte hyperproliferation, erythema, as well as a form of pruritus, involving cutaneous discomfort. There is evidence from both clinical and murine models of psoriasis that chemical or surgical depletion of small-diameter sensory nerves/nociceptors benefits the condition, but the mechanisms are unclear. Hence, we aimed to understand the involvement of sensory nerve mediators with a murine model of psoriasis and associated spontaneous behaviors, indicative of cutaneous discomfort. We have established an Aldara model of psoriasis in mice and chemically depleted the small-diameter nociceptors in a selective manner. The spontaneous behaviors, in addition to the erythema and skin pathology, were markedly improved. Attenuated inflammation was associated with reduced dermal macrophage influx and production of reactive oxygen/nitrogen species (peroxynitrite and protein nitrosylation). Subsequently, this directly influenced observed behavioral responses. However, the blockade of common sensory neurogenic mechanisms for transient receptor potential (TRP)V1, TRPA1, and neuropeptides (substance P and calcitonin gene-related peptide) using genetic and pharmacological approaches inhibited the behaviors but not the inflammation. Thus, a critical role of the established sensory TRP-neuropeptide pathway in influencing cutaneous discomfort is revealed, indicating the therapeutic potential of agents that block that pathway. The ongoing inflammation is mediated by a distinct sensory pathway involving macrophage activation.-Kodji, X., Arkless, K. L., Kee, Z., Cleary, S. J., Aubdool, A. A., Evans, E., Caton, P., Pitchford, S. C., Brain, S. D. Sensory nerves mediate spontaneous behaviors in addition to inflammation in a murine model of psoriasis.

Alteration of serum thymus and activation-regulated chemokine level during biologic therapy for psoriasis: Possibility as a marker reflecting favorable response to anti-interleukin-17A agents

Biologics show great efficacy in treating psoriasis, a chronic inflammatory skin disease. The high cost and side-effects of biologics, dose-reduction, elongation of administration interval and suspension are possible options. However, there has been no reliable biomarker we can use when we consider these moderations in therapy. This study was conducted to test the possibility of using serum thymus and activation-regulated chemokine (TARC) level as an indicator for step down of biologic therapy. Serum TARC level was measured in 70 psoriatic patients at Asahikawa Medical University, and a correlation of TARC and severity of skin lesions was analyzed. Referring to serum TARC level, psoriatic patients can be divided into two groups. One is a population in which serum TARC level is positively correlated with severity of skin lesions, and the other is a population with low psoriatic severity and high TARC level. Serum TARC level was higher in the group that achieved PASI-clear with biologics than in the group which did not achieve PASI-clear. Among biologics, the group treated with secukinumab, an anti-interleukin (IL)-17A agent, showed significantly higher TARC level compared with the group treated with anti-tumor necrosis factor agents. In certain populations achieving PASI-clear, serum TARC level may be a potent marker reflecting better response to IL-17A inhibitors, and in this case step down of treatment for psoriasis is possible.