Comprehensive plasma cytokine and chemokine profiling in prurigo nodularis reveals endotypes in Type 2 inflammation.

Prurigo nodularis (PN) is a chronic inflammatory skin disease that is associated with variability in peripheral blood eosinophil levels and response to T-helper 2 targeted therapies (Th2). Our objective was to determine whether circulating immune profiles with respect to type 2 inflammation differ by race and peripheral blood eosinophil count. Plasma from 56 PN patients and 13 matched healthy controls was assayed for 54 inflammatory biomarkers. We compared biomarker levels between PN and HCs, among PN patients based on absolute eosinophil count, and across racial groups in PN. Eleven biomarkers were elevated in PN versus HCs including interleukin (IL)-12/IL-23p40, tumor necrosis factor-alpha (TNF-α), Thymic stromal lymphopoietin (TSLP), and macrophage-derived chemokine (MDC/CCL22). Additionally, PN patients with AEC > 0.3 K cells/µL had higher Th2 markers (eotaxin, eotaxin-3, TSLP, MCP-4/CCL13), and African American PN patients had lower eosinophils, eotaxin, and eotaxin-3 versus Caucasian and Asian PN patients (p < 0.05 for all). Dupilumab responders had higher AEC (p < 0.01), were more likely to be Caucasian (p = 0.02) or Asian (p = 0.05) compared to African Americans, and more often had a history of atopy (p = 0.08). This study suggests that blood AEC > 0.3 K and Asian and Caucasian races are associated with Th2 skewed circulating immune profiles and response to Th2 targeted therapies.

Increased cardiovascular risks and mortality in prurigo nodularis: a global cohort study.

BACKGROUND: Prurigo nodularis (PN) presents with intensely itchy hard nodules. Despite being limited to the skin, PN was noted to be associated with systemic diseases including diabetes and chronic renal failure. In previous smaller retrospective studies, several cardiac and vascular diseases were found more frequently in patients with PN. However, small cohort sizes, partially discrepant outcomes, missing data, and incomplete risk assessment limit these findings. METHODS: Electronic health records (EHR)s of 64,801 patients (59.44% females) with PN and an equal sized propensity-matched control group were retrieved. In these cohorts, the risks to develop cardiac and vascular diseases and mortality following the diagnosis of PN were determined. Sub-analyses included stratification for sex, ethnicity, and treatments. FINDINGS: PN was associated with a higher risk for a broad range of acute cardiac events including heart failure and myocardial infarction. For example, the hazard ratio of myocardial infarction was 1.11 (95%-CI: 1.041-1.184, p = 0.0015) following PN diagnosis. Also, all-cause mortality was higher in patients with PN. Further, chronic vascular as well as structural heart diseases, e.g., peripheral arterial disease, chronic ischaemic heart disease and valval disorders were found more frequently following a PN diagnosis. Risks were more pronounced in white and female patients. Having established an increased risk for death and cardiovascular disease, we next addressed if dupilumab that has been recently licenced for use in this indication can modulate these risks. The risk of death but not of any cardiovascular disease was slightly reduced in patients with PN treated with dupilumab as opposed to those treated with systemic therapies other than dupilumab. The study is limited by retrospective data collection and reliance on ICD10-disease classification. INTERPRETATION: PN is associated with higher mortality and an increased risk for the development of a wide range of cardiac and vascular diseases. Health care professionals should take this into account when managing patients with PN. FUNDING: This work was supported by the University of Lübeck, the Deutsche Forschungsgemeinschaft and the State of Schleswig-Holstein.

Dysregulation of the Skin-Liver Axis in Prurigo Nodularis: An Integrated Genomic, Transcriptomic, and Population-Based Analysis.

Pruritus has long been linked to hepatic dysfunction; however, there are limited data characterizing the association between liver disease and prurigo nodularis (PN), a chronic inflammatory skin disease featuring severe pruritis. We thus conducted a cross-sectional analysis of hepatic comorbidities in PN patients using TriNetX, a large global health research network. This analysis revealed that PN patients had a higher risk (p < 0.001) of developing liver cirrhosis, acute and subacute hepatic failure, inflammatory liver disease, chronic hepatitis, nonalcoholic steatohepatitis, portal hypertension, fatty liver, chronic passive congestion of the liver, and hepatocellular carcinoma compared with healthy controls. The cumulative incidence of liver disease was about three times higher in PN patients compared with healthy controls. These findings provided the basis for translational studies to investigate a genetic mechanism for this association. Cutaneous transcriptomic analysis performed on PN patients revealed the dysregulation of genes related to hepatic failure in lesional PN compared with both nonlesional PN and control skin. Similarly, gene set variation analysis (GSVA) revealed a significantly increased (p < 0.05) activation of liver metabolism, chronic hepatic failure, acute hepatic failure, cholestatic liver disease, polycystic liver disease, and hepatocellular carcinoma pathways in lesional PN compared with control skin. A subsequent genome-wide association study (GWAS) identified shared single-nucleotide polymorphisms (SNPs) in the genes AR, EDIL3, MACROD2, PCSK5, RUNX1T1, TENM4, and ZEB2 between PN and liver disease from the FinnGen cohort. Significant dysregulation of the skin-liver axis in PN patients may explain the increased incidence and severity of hepatic comorbidities and help identify future therapeutic targets for PN.

A systematic review of interleukin-31 inhibitors in the treatment of prurigo nodularis.

BACKGROUND: Prurigo nodularis (PN) is a neuroimmunological skin disease. Severe itching is the most challenging symptom which affects patients' quality of life. T helper 2-derived cytokines, such as interleukin-31 and oncostatin M (OSM), play a crucial role in PN pathogenesis. Nemolizumab and vixarelimab are two biologics acting as IL-31 inhibitors. Vixarelimab also suppresses the OSM activity. This systematic review evaluates the efficacy and safety of nemolizumab and vixarelimab in PN management. METHODS: A systematic search was conducted in PubMed/Medline, Ovid Embase, and Web of Science up to September 17th, 2023. Clinical trials and cohort studies published in English were included. RESULTS: Among a total of 96 relevant records, five were included. The results of four studies with 452 patients using nemolizumab showed that a significantly higher percentage of patients treated with nemolizumab demonstrated a reduction in peak pruritus numerical rating scale (PP-NRS) and investigator's global assessment along with improved sleep disturbance (SD) and quality of life than the placebo group. Moreover, one study administered vixarelimab to 49 PN patients, and their finding illustrated a higher rate of subjects who received vixarelimab experienced ≥ 4-point diminution in worst itch NRS, visual analog scale, healing of representative lesions, and SD quality compared to the placebo group. CONCLUSIONS: IL-31 inhibitors suggest distinct advantages in improving pruritus, sleep quality, and overall quality of life in subjects with moderate-to-severe PN. Further clinical studies are recommended to compare the effectiveness of these biologics to other therapeutic choices.

Prurigo nodularis: new insights into pathogenesis and novel therapeutics.

Prurigo nodularis (PN) is an inflammatory skin condition characterized by intensely pruritic nodules on the skin. Patients with PN suffer from an intractable itch-scratch cycle leading to impaired sleep, psychosocial distress and a significant disruption in quality of life. The pathogenesis of PN is associated with immune and neural dysregulation, mediated by inflammatory cytokines [such as interleukin (IL)-4, -13, -17, -22 and -31] and neuropeptides (such as substance P and calcitonin gene-related peptide). There is a role for type 2 inflammation in PN in addition to T-helper (Th)17 and Th22-mediated inflammation. The neuroimmune feedback loop in PN involves neuropeptides released from nerve fibres that cause vasodilation and further recruitment of inflammatory cells. Inflammatory cells, particularly mast cells and eosinophils, degranulate and release neurotoxins, as well as nerve growth factor, which may contribute to the neuronal hyperplasia seen in the dermis of patients with PN and neural sensitization. Recent studies have also indicated underlying genetic susceptibility to PN in addition to environmental factors, the existence of various disease endotypes centred around degrees of type 2 inflammation or underlying myelopathy or spinal disc disease, and significant race and ethnicity-based differences, with African Americans having densely fibrotic skin lesions. Dupilumab became the first US Food and Drug Administration-approved therapeutic for PN, and there are several other agents currently in development. The anti-IL-31 receptor A inhibitor nemolizumab is in late-stage development with positive phase III data reported. In addition, the oral Janus kinase (JAK) 1 inhibitors, abrocitinib and povorcitinib, are in phase II trials while a topical JAK1/2 inhibitor, ruxolitinib, is in phase III studies.

Prurigo nodularis (PN) is a chronic skin condition featuring extremely itchy nodules on the skin of the legs, arms and trunk of the body. PN affects approximately 72 per 100 000 people and the severe itch associated with the condition can negatively impact a person's sleep, work and social life. However, the cause of PN remains unclear. Current understanding of PN is based on imbalances in the immune system leading to widespread inflammation as well as dysregulation of the nerves in the skin. Immune molecules released from T cells [such as interleukin (IL)-4, -13, -31, -17, -22 and -31] increase systemic inflammation and are elevated in people with PN. Activated inflammatory cells (such as mast cells or eosinophils) may also release factors that promote inflammation, itch and neural changes within the skin. Neural dysregulation in PN features a lower density of itch-sensing nerve fibres in the epidermis (upper layer of the skin) and a higher density of itch-sensing nerve fibres in the dermis (lower layer of the skin). Because the pathogenesis of PN is not fully understood, the therapies available for PN have had limited success in reducing itch and nodules. The only drug currently approved for PN in the USA and Europe is dupilumab, an IL-4Rα inhibitor that blocks signalling through IL-4 and IL-13, which is undergoing post-marketing surveillance. Other new drugs are being assessed in various phases of clinical trials, including nemolizumab, vixarelimab, barzolvolimab, ruxolitinib, abrocitinib, povorcitinib and nalbuphine.

A randomized, double-blinded, vehicle-controlled clinical trial of topical cryosim-1, a synthetic TRPM8 agonist, in prurigo nodularis.

BACKGROUND: Prurigo nodularis (PN) is an intensively pruritic skin disease that negatively influences quality of life. Cryosim-1 (Intrinsic IB Spot) is a synthetic, selective transient receptor potential melastatin 8 agonist. AIMS: To investigate the efficacy and safety of cryosim-1 in PN patients. PATIENTS/METHODS: A randomized, double-blinded, placebo-controlled clinical trial including 30 patients was conducted. The numerical rating scale (NRS) of pruritus was evaluated before and 2 h after cryosim-1 application at every visit. RESULTS: At week 8, the mean pruritus NRS before serum application (4.7 ± 0.4 treatment, 6.1 ± 0.5 placebo; p = 0.045) and 2 h after serum application (2.8 ± 0.4 treatment, 4.3 ± 0.5 placebo; p = 0.031) were significantly lower in the treatment group, and the mean NRS for sleep disorder was significantly lower in the treatment group (2.2 ± 0.5 treatment, 4.2 ± 0.8 placebo; p = 0.031). The mean satisfaction scales for pruritus improvement were significantly higher in the treatment group (7.2 ± 0.6) than in the placebo group (4.0 ± 0.9; p = 0.005). There was no difference in TEWL between the two groups, and no adverse reactions were reported. CONCLUSIONS: Cryosim-1 is a safe and effective topical treatment for PN patients.

Clinical Characteristics and Treatment Outcomes of Prurigo Nodularis: A Retrospective Study.

BACKGROUND: Prurigo nodularis (PN) is a complex chronic skin disease characterized by severe pruritic nodules. PN is often associated with mental health disorders and chronic medical comorbidities. Until recently, PN treatment has been challenging and difficult. OBJECTIVES: This study aims to describe the demographic, clinical characteristics, and comorbidities associated with PN. Also, we aim to describe the effectiveness of systemic therapies, including methotrexate, cyclosporine, and narrow band ultraviolet (NB-UVB) in adult patients with PN. METHODS: This is a retrospective chart review of adult patients diagnosed with PN at Hamilton Health Science Center and/or McMaster University in Hamilton, Ontario, between 2015 and 2023. RESULTS: The study included 81 patients (57% female). The mean age was 52.8 years, and the mean age of PN diagnosis was 50 years. Reported symptoms included: itching (100%), dry skin (53%), pain (17%), and burning sensation (5%). Lower and upper extremities were the most common areas involved in 93% and 69%, respectively. Mental health disorders were present in 79% of patients, with depression (58%) and anxiety (52%) being the most common. Atopic dermatitis was the most common skin comorbidity noted. Treatments used included cyclosporine, and NB-UVB, and MTX, which resulted in significant improvement of pruritus in 38%, 35%, and 31% of patients, respectively, at week 16. CONCLUSIONS: PN is associated with increased risk of mental health disorders and other medical comorbidities. Cyclosporine, methotrexate, and NB-UVB therapy may be effective treatment options, however clinicians must consider the potential short- and long-term adverse effects of these treatments.

Non-Systemic Medication for the Treatment of Prurigo Nodularis: A Systematic Review.

Prurigo nodularis (PN) is a skin disease characterized by firm, itchy, erythematous lesions. Treatment consists of systemic and non-systemic modes of therapy. Non-systemic forms of treatment are first-line and include topical corticosteroids, topical steroid-sparing agents, and phototherapy. The objective was to review the efficacy of non-systemic treatment used to treat PN. A systematic search was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered with PROSPERO (CRD42023412012). The search consisted of keywords and Medical Subject Heading (MeSH) terms and translated to Ovid MEDLINE, Embase, and Scopus. Google Scholar was also searched for the first 200 articles. Article quality of evidence was scored using GRADE criteria. The search yielded 1151 results; 37 met criteria for inclusion. There were 14 studies on phototherapy, and 11 studies on topical corticosteroids, most of which were also combined with topical antihistamines, antipruritics, and/or phototherapy. There were 2 studies each on topical antipruritics used in isolation, vitamin D analogues, and intralesional triamcinolone acetonide. There was 1 study each on topical pimecrolimus, tacrolimus, 2% dinitrochlorobenzene, cryotherapy, acupuncture, and the Paul Gerson Unna boot. Most were case reports and case series, although 2 randomized controlled trials on phototherapy and topical pimecrolimus were included. Corticosteroids had varying levels of positive response in patients and appeared more effective when used in combination or under occlusive dressing. Phototherapy is likely effective, but the risk of relapse is high. Cryotherapy may also be a lesion-directed agent to circumvent challenges to adherence and avoidance of systemic medication.

A critical evaluation of nemolizumab for prurigo nodularis.

INTRODUCTION: Prurigo nodularis (PN) is a chronic inflammatory skin condition that presents with intensely pruritic, hyperkeratotic nodules. The pathophysiology underlying PN is not entirely clear, making treatment challenging. Patients often require a multimodal approach, although many of the available therapies have low efficacy or adverse effects. AREAS COVERED: In this review, we discuss the use of nemolizumab for the treatment of PN in adults. Nemolizumab is a biological therapy that reduces type 2 cytokines and the neuroimmune response implicated in the pathophysiology of PN. It also helps maintain skin barrier integrity, which may be damaged during the vicious itch-scratch cycle. Nemolizumab has demonstrated great efficacy in improving itch and clearing lesions in recent clinical trials with respectable tolerance. EXPERT OPINION: Nemolizumab is a promising drug for PN that seems comparable to the recently approved dupilumab in terms of its therapeutic effect and excellent safety profile, although nemolizumab may work more rapidly on itch. JAK inhibitors are also emerging as competitors of biologics for PN, however, their safety profile in this population may differ. Trials evaluating these drugs are needed to assess which is preferable. Additional data on the durability and longevity of nemolizumab for PN treatment is highly anticipated.

Disease burden and treatment satisfaction in patients with prurigo nodularis in Japan.

Prurigo nodularis (PN) is a chronic inflammatory skin disorder with a high disease burden. In this cross-sectional, web-based survey, Global Questions (GQ), the Numerical Rating Scales (NRS) for pruritus, burning sensation and sleep disturbance, the Short-Form-8 (SF-8) Health Survey, Dermatology Life Quality Index (DLQI), Patient Health Questionnaire 9 (PHQ-9), Work Productivity and Activity Impairment (WPAI), and Treatment Satisfaction Questionnaire for Medication-9 (TSQM-9) scores were used to assess the current disease burden and treatment satisfaction among patients with PN in Japan. In total, 97 patients were included (55.7% male, median age 51 years, median duration of PN 36 months). Based on GQ scores, 35.1% of patients had mild disease, 50.5% moderate, and 14.4% severe disease. Disease burden increased as the severity of PN increased, as indicated by worsening of pruritus NRS scores and quality of life (DLQI, PHQ-9, WPAI presenteeism, work productivity loss, and activity impairment scores). Patients with comorbid atopic dermatitis (AD) also had more intense pruritus than those without AD. Mean ± standard deviation TSQM-9 scores for effectiveness, convenience, and global satisfaction were 54.7 ± 18.1%, 62.4 ± 15.2%, and 57.4 ± 15.9%, respectively. TSQM-9 scores were lowest in patients receiving the most intensive guideline-directed treatment (i.e., topical corticosteroids + systemic oral corticosteroids or cyclosporine), highlighting an unmet need for more effective treatment options for patients with PN. In summary, Japanese patients with PN reported increased disease burden and reduced treatment satisfaction with increased disease severity, despite the use of guideline-recommended therapies.

Single-cell profiling of prurigo nodularis demonstrates immune-stromal crosstalk driving profibrotic responses and reversal with nemolizumab.

BACKGROUND: Prurigo nodularis (PN) is a chronic neuroimmune skin disease characterized by bilaterally distributed pruritic hyperkeratotic nodules on extremities and trunk. Neuroimmune dysregulation and chronic scratching are believed to both induce and maintain the characteristic lesions. OBJECTIVES: This study sought to provide a comprehensive view of the molecular pathogenesis of PN at the single-cell level to identify and outline key pathologic processes and the cell types involved. Features that distinguish PN skin from the skin of patients with atopic dermatitis were of particular interest. We further aimed to determine the impact of the IL31RA antagonist, nemolizumab, and its specificity at the single-cell level. METHODS: Single-cell RNA-sequencing of skin from 15 healthy donors and nonlesional and lesional skin from 6 patients each with PN and atopic dermatitis, combined with spatial-sequencing using the 10x Visium platform. Integration with bulk RNA-sequencing data from patients treated with nemolizumab. RESULTS: This study demonstrates that PN is an inflammatory skin disease characterized by both keratinocyte proliferation and activation of profibrotic responses. This study also demonstrates that the COL11A1+ fibroblast subset is a major contributor to fibrosis and is predominantly found in the papillary dermis of PN skin. Activation of fibrotic responses is the main distinguishing feature between PN and atopic dermatitis skin. This study further shows the broad effect of nemolizumab on PN cell types, with a prominent effect driving COL11A1+ fibroblast and keratinocyte responses toward normal. CONCLUSIONS: This study provides a high-resolution characterization of the cell types and cellular processes activated in PN skin, establishing PN as a chronic fibrotic inflammatory skin disease. It further demonstrates the broad effect of nemolizumab on pathological processes in PN skin.

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.

Prurigo-like atopic dermatitis in a child with CARD11-associated severe combined immunodeficiency successfully treated with dupilumab.

A 12-year-old boy affected by severe combined immunodeficiency due to a heterozygous variant in the CARD domain of CARD11, c.169G>A; p.Glu57Lys, developed severe atopic dermatitis and alopecia areata. After failure of conventional systemic therapy, dupilumab was administered at a dose of 400 mg subcutaneously, followed by 200 mg every 14 days. The patient had an excellent clinical response after 1 month and complete remission after a year, with the absence of side effects, demonstrating good efficacy and safety profile.

A critical review of dupilumab for adult patients with prurigo nodularis.

INTRODUCTION: Prurigo nodularis (PN) is a chronic inflammatory skin condition that presents with pruritus and hyperkeratotic nodules. These symptoms impact patients' quality of life and mental health. Treating prurigo nodularis is challenging, and many of the available topical and systemic therapies have limited efficacy and a myriad of adverse effects. AREAS COVERED: In this article, we discuss the use of dupilumab for adult patients with prurigo nodularis. Dupilumab is a biologic that inhibits Th2-mediated inflammation and has been successfully used to treat a variety of dermatologic disorders. Dupilumab has revolutionized the management of PN, with recent clinical trials showing its efficacy in treating both pruritus and prurigo nodules, as well as improving quality of life. It has a favorable safety profile and is well tolerated. Other novel treatments are also currently under investigation for the treatment of PN, with early studies reporting promising results. EXPERT OPINION: Dupilumab is becoming the drug of choice for the treatment of PN and may also be effective in treating patients with systemic underlying causes of their PN, although more studies are needed to assess this. Trials evaluating the long-term efficacy and durability of dupilumab in PN are also of interest.

INDIVIDUAL ARTICLE: Management of Prurigo Nodularis.

BACKGROUND: Prurigo nodularis (PN) is a chronic disease characterized by intense pruritus and nodular lesions associated with reduced quality of life. Until recently, no US Food and Drug Administration (FDA)-approved therapies have been available for the management of PN. Treatment regimens have been highly variable and clinical management guidelines are lacking overall; formal treatment guidelines do not exist within the US. In 2022, dupilumab became the first FDA-approved medication for PN. Multiple novel agents that target the neuroimmune underpinnings of the disease are currently in development and show promise for this challenging disorder. OBJECTIVE: To review current treatments and emerging therapies for effective management of patients with PN. METHODS: We reviewed publications on PN management identified from PubMed, Embase, Web of Science, and the Cochrane Library. We also included publicly available data on clinical trials for PN therapies reported on the US National Library of Medicine ClinicalTrials.gov, the International Conference on Harmonisation-Good Clinical Practice (ICH-GCP) Database, and the European Clinical Trials (EudraCT) Database. RESULTS: The recommended management of PN begins with an assessment of disease severity, including disease burden and pruritus intensity, and evaluation of comorbid medical disorders. Treatment goals include resolution of itch, improvement in nodules or cutaneous lesions, and improvement in quality of life. Therapies should be selected based on a patient’s clinical presentation and comorbidities. Treatment should simultaneously address the neural and immunologic components of PN. Combination therapy, particularly with conventional agents, may be beneficial. LIMITATIONS: Data on most conventional PN treatments are limited to anecdotal reports, small clinical trials, or expert consensus recommendations. No head-to-head comparative trials have evaluated the relative efficacy of conventional and/or emerging agents, or combination therapy. CONCLUSION: An effective treatment approach for patients with PN should reduce pruritus, allow nodular lesions to heal, and improve individual quality of life. The treatment landscape for PN is rapidly evolving with one FDA-approved agent and several new promising therapies on the horizon. J Drugs Dermatol. 2023;22:12(Suppl 2):s15-22.

Molecular mechanisms of pruritus in prurigo nodularis.

Pruritus is the most common symptom of dermatological disorders, and prurigo nodularis (PN) is notorious for intractable and severe itching. Conventional treatments often yield disappointing outcomes, significantly affecting patients' quality of life and psychological well-being. The pathogenesis of PN is associated with a self-sustained "itch-scratch" vicious cycle. Recent investigations of PN-related itch have partially revealed the intricate interactions within the cutaneous neuroimmune network; however, the underlying mechanism remains undetermined. Itch mediators play a key role in pruritus amplification in PN and understanding their action mechanism will undoubtedly lead to the development of novel targeted antipruritic agents. In this review, we describe a series of pruritogens and receptors involved in mediating itching in PN, including cytokines, neuropeptides, extracellular matrix proteins, vasculogenic substances, ion channels, and intracellular signaling pathways. Moreover, we provide a prospective outlook on potential therapies based on existing findings.

Dupilumab for the Treatment of Prurigo Nodularis.

Prurigo nodularis (PN) is a chronic inflammatory skin condition characterized by the presence of pruritic nodules. Dupilumab was approved by the US Food and Drug Administration in September 2022 and Health Canada in July 2023 for the treatment of PN. Dupilumab is a human monoclonal immunoglobulin G4 antibody that binds the interleukin (IL)-4 receptor alpha subunit, blocking intercellular signalling of IL-4 and IL-13. Inhibition of these cytokines downregulates the inflammatory response and improves disease severity and pruritus. Two randomized controlled trials have shown dupilumab to be effective in reducing pruritus and lesion count in patients with PN. The approval of dupilumab for PN represents the first approved therapy for PN and may indicate a paradigm shift in the way this condition is treated.

Systemic Medication for the Treatment of Prurigo Nodularis-A Systematic Review.

IMPORTANCE: Prurigo nodularis (PN) is a debilitating inflammatory skin disease characterized by red to violaceous pruritic lesions. The goal of therapy is to break the scratch-itch cycle. Treatment varies and often requires a multimodal approach to target both immune and neural mediated aspects of disease. OBJECTIVES: To review the efficacy of systemic treatment used to treat PN. EVIDENCE REVIEW: A systematic search of keywords and Medical Subject Headings was performed in Ovid MEDLINE, Embase, Scopus, and ClinicalTrials.gov. The first 200 results of an abbreviated search in Google Scholar were also included. PRISMA guidelines were followed and the review was registered on PROSPERO (CRD42023412012). GRADE criteria were used to assess articles for quality of evidence. FINDINGS: The search resulted in 1153 articles; 382 were duplicates, 643 were irrelevant, 19 were not retrieved, 21 were abstract only, and 88 are included in this review. There were 24 studies on dupilumab, 16 on thalidomide, 8 on cyclosporin, 7 on methotrexate, 3 each on lenalidomide and aprepitant, 2 each on alitretinoin, apremilast, baricitinib, gabapentin, intravenous (IV) immunoglobulins, pregabalin, tofacitinib, and 1 each on amitriptyline, azathioprine, butorphanol, isoquercitin, IV dexamethasone-cyclophosphamide/ oral cyclophosphamide, ketotifen, metronidazole, montelukast, nalbuphine, nemolizumab, serolopitant, tacrolimus, and herose derma zima capsule. CONCLUSIONS AND RELEVANCE: Dupilumab reduces pruritus and appearance of lesions and is associated with the fewest number of side effects. Thalidomide and pregabalin are also effective, but their long-term use is limited by muscle and nerve pain. Janus Kinase inhibitors may be beneficial, but large population studies are lacking.