Increased systemic levels of centrally acting B-type Natriuretic Peptide are associated with chronic Itch of different types

B-Type natriuretic peptide (BNP) is an itch-selective neuropeptide that was shown to play a role in both histaminergic and non-histaminergic itch in mice. It was also shown that elevated serum BNP is linked to increased pruritus in non-diabetic hemodialysis patients. This study examined plasma BNP levels of 77 patients and N-Terminal pro-BNP (NT-proBNP) levels of 33 patients with differing types of chronic itch to see if BNP and NT-proBNP levels can correlate with itch severity. Plasma BNP and NT-proBNP levels of all itch patients correlated to itch NRS, and in particular for patients with Chronic Pruritus of Unknown Origin (CPUO). Based on this clinical observation, this study further showed that increasing pathophysiological levels of BNP in mice by IV or osmotic pump induced significant scratching. Additionally, pharmacological and ablation strategies determined that BNP acts centrally by activating the natriuretic peptide receptor A (NPRA) in the dorsal horn of the spinal cord. These data support that BNP and NT-proBNP levels are associated with chronic itch and may be used in clinical setting.

IL-33 potentiates histaminergic itch

BACKGROUND

Itch is a common symptom that can greatly diminish quality of life. Histamine is a potent endogenous pruritogen, and while antihistamines are often the first-line treatment for itch, in conditions like chronic spontaneous urticaria (CSU), many patients remain symptomatic while receiving maximal doses. Mechanisms that drive resistance to antihistamines are poorly defined.

OBJECTIVES

Signaling of the alarmin cytokine IL-33 in sensory neurons is postulated to drive chronic itch by inducing neuronal sensitization to pruritogens. Thus, we sought to determine if IL-33 can augment histamine-induced (histaminergic) itch.

METHODS

Itch behavior was assessed in response to histamine after IL-33 or saline administration. Various stimuli and conditional and global knockout mice were utilized to dissect cellular mechanisms. Multiple existing transcriptomic data sets were evaluated, including single-cell RNA sequencing of human and mouse skin, microarrays of isolated mouse mast cells at steady state and after stimulation with IL-33, and microarrays of skin biopsy samples from subjects with CSU and healthy controls.

RESULTS

IL-33 amplifies histaminergic itch independent of IL-33 signaling in sensory neurons. Mast cells are the top expressors of the IL-33 receptor in both human and mouse skin. When stimulated by IL-33, mouse mast cells significantly increase IL-13 levels. Enhancement of histaminergic itch by IL-33 relies on a mast cell- and IL-13-dependent mechanism. IL-33 receptor expression is increased in lesional skin of subjects with CSU compared to healthy controls.

CONCLUSIONS

Our findings suggest that IL-33 signaling may be a key driver of histaminergic itch in mast cell-associated pruritic conditions such as CSU.

Editorial Commentary: Risk of Lateral Hinge Fracture After Knee Medial Opening-Wedge High Tibial Osteotomy Can Be Reduced With Osteotomy at the Level of the Proximal Tibiofibular Joint and Gap Width of No Larger Than 11 mm

Medial opening-wedge high tibial osteotomies are commonly performed to treat varus deformity and medial compartment osteoarthritis of the knee in active younger individuals. A common complication of this procedure is the development of a lateral hinge fracture. This can occur both acutely and with a delayed presentation. There are many considerations to reduce this fracture, including biplanar versus monoplanar osteotomy, amount of correction/gap width, level of the osteotomy, and lateral cortical distance of the osteotomy. To best reduce the risk of a lateral hinge fracture, place the level of the osteotomy at the level of the proximal tibiofibular joint, and maintain a gap width of no larger than ∼11 mm.

Estimating meaningful change thresholds for Skin Pain-Numeric Rating Scale, Sleep-Numeric Rating Scale and Dermatology Life Quality Index in patients with prurigo nodularis

BACKGROUND

Prurigo nodularis (PN) is characterized by intensely itchy nodules/lesions and skin pain, which can have a substantial impact on health-related quality of life (HRQoL). Treatment benefits on such symptoms and impacts are best assessed in trials using patient-reported outcome (PROs) instruments such as Skin Pain Numerical Rating Scale (NRS), Sleep-NRS and Dermatology Life Quality Index (DLQI). However, no guidance exists for interpreting meaningful changes in scores using these PROs in patients with PN.

OBJECTIVES

The main objective was to derive within-patient (responder definition) and between-group improvement thresholds for interpreting Skin Pain-NRS, Sleep-NRS and DLQI total scores in patients with PN. The measurement properties of the three PROs were also evaluated.

METHODS

Intention-to-treat (ITT), blinded and pooled data were used from the Phase 3 PRIME (NCT04183335) and PRIME2 (NCT04202679) studies evaluating the efficacy of dupilumab in adult patients with PN. Anchor- and distribution-based methods were applied to derive responder definition and between-group thresholds for Skin Pain-NRS, Sleep-NRS and DLQI. Data were additionally used to examine the instrument measurement properties, including reliability, validity and responsiveness.

RESULTS

A total of 311 patients (mean age 49.5 years, 65.3% female) were included in the pooled ITT population. The within-patient improvement threshold for Skin Pain-NRS was estimated as 4.0 points, 2.0 points for Sleep-NRS and 9.0 points for DLQI total score. A 1.5-point improvement in Skin Pain-NRS scores, 1.0-point in Sleep-NRS and 4.0-point in DLQI indicated a between-group meaningful change. Adequate to good psychometric properties were demonstrated for all three instruments.

CONCLUSIONS

The results of this study can aid interpretation of Skin Pain-NRS, Sleep-NRS and DLQI scores in patients with PN in both clinical trials and clinical practice to better understand and treat PN-related skin pain and the impact of PN on sleep quality and HRQoL.

Sensory neurons promote immune homeostasis in the lung

Cytokines employ downstream Janus kinases (JAKs) to promote chronic inflammatory diseases. JAK1-dependent type 2 cytokines drive allergic inflammation, and patients with JAK1 gain-of-function (GoF) variants develop atopic dermatitis (AD) and asthma. To explore tissue-specific functions, we inserted a human JAK1 GoF variant (JAK1GoF) into mice and observed the development of spontaneous AD-like skin disease but unexpected resistance to lung inflammation when JAK1GoF expression was restricted to the stroma. We identified a previously unrecognized role for JAK1 in vagal sensory neurons in suppressing airway inflammation. Additionally, expression of Calcb/CGRPβ was dependent on JAK1 in the vagus nerve, and CGRPβ suppressed group 2 innate lymphoid cell function and allergic airway inflammation. Our findings reveal evolutionarily conserved but distinct functions of JAK1 in sensory neurons across tissues. This biology raises the possibility that therapeutic JAK inhibitors may be further optimized for tissue-specific efficacy to enhance precision medicine in the future.

An IL-4 signalling axis in bone marrow drives pro-tumorigenic myelopoiesis

Myeloid cells are known to suppress antitumour immunity1. However, the molecular drivers of immunosuppressive myeloid cell states are not well defined. Here we used single-cell RNA sequencing of human and mouse non-small cell lung cancer (NSCLC) lesions, and found that in both species the type 2 cytokine interleukin-4 (IL-4) was predicted to be the primary driver of the tumour-infiltrating monocyte-derived macrophage phenotype. Using a panel of conditional knockout mice, we found that only deletion of the IL-4 receptor IL-4Rα in early myeloid progenitors in bone marrow reduced tumour burden, whereas deletion of IL-4Rα in downstream mature myeloid cells had no effect. Mechanistically, IL-4 derived from bone marrow basophils and eosinophils acted on granulocyte-monocyte progenitors to transcriptionally programme the development of immunosuppressive tumour-promoting myeloid cells. Consequentially, depletion of basophils profoundly reduced tumour burden and normalized myelopoiesis. We subsequently initiated a clinical trial of the IL-4Rα blocking antibody dupilumab2-5 given in conjunction with PD-1/PD-L1 checkpoint blockade in patients with relapsed or refractory NSCLC who had progressed on PD-1/PD-L1 blockade alone (ClinicalTrials.gov identifier NCT05013450 ). Dupilumab supplementation reduced circulating monocytes, expanded tumour-infiltrating CD8 T cells, and in one out of six patients, drove a near-complete clinical response two months after treatment. Our study defines a central role for IL-4 in controlling immunosuppressive myelopoiesis in cancer, identifies a novel combination therapy for immune checkpoint blockade in humans, and highlights cancer as a systemic malady that requires therapeutic strategies beyond the primary disease site.

Abrocitinib Provides Rapid and Sustained Improvement in Skin Pain and Is Associated with Improved Quality of Life Outcomes in Adult and Adolescent Patients with Moderate-to-Severe Atopic Dermatitis

BACKGROUND

Skin pain in atopic dermatitis (AD) increases with disease severity and is associated with substantial quality of life (QoL) burden.

OBJECTIVES

The aim of the study was to evaluate abrocitinib efficacy on skin pain and QoL in adults and adolescents with moderate-to-severe AD.

METHODS

This post hoc analysis included data with abrocitinib administered as monotherapy (pooled phase 2b [NCT02780167] and phase 3 JADE MONO-1 [NCT03349060] and JADE MONO-2 [NCT03575871]) or in combination with topical therapy (phase 3 JADE COMPARE [NCT03720470] and JADE TEEN [NCT03796676]). Patients received oral, once-daily abrocitinib 200 mg, abrocitinib 100 mg, or placebo for 12 or 16 weeks (JADE COMPARE). Skin pain was rated using the Pruritus and Symptoms Assessment for Atopic Dermatitis (PSAAD) skin pain Numerical Rating Scale (NRS) item ("How painful was your skin over the past 24 h?") on a scale from 0 (not painful) to 10 (extremely painful). Itch (Peak Pruritus NRS) and QoL (Dermatology Life Quality Index or Children's Dermatology Life Quality Index) were assessed. Least squares mean (LSM) change from baseline was analyzed using mixed-effects repeated measures modeling.

RESULTS

A total of 1,822 patients (monotherapy pool, n = 942; JADE COMPARE, n = 595; and JADE TEEN, n = 285) were analyzed. LSM change from baseline in PSAAD skin pain score was significantly greater with abrocitinib versus placebo from week 2 through week 12 or 16 across all 3 study populations and occurred in a dose-dependent manner. A greater proportion of patients achieved a ≥4-point improvement from baseline in PSAAD skin pain score with abrocitinib (200 mg and 100 mg) versus placebo in the monotherapy pool (56% and 38% vs. 12%; week 12), JADE COMPARE (72% and 52% vs. 26%; week 16), and JADE TEEN (51% and 60% vs. 31%; week 12). Additionally, a greater proportion of patients achieved a stringent threshold of skin pain improvement (PSAAD skin pain score <2) with abrocitinib versus placebo. Adults and adolescents who achieved a ≥4-point improvement in skin pain reported greater QoL improvement than those who did not achieve a ≥4-point improvement. A positive correlation (≥0.3) was observed between skin pain and QoL and separately between skin pain and itch across the 3 study populations.

CONCLUSION

Abrocitinib as monotherapy or in combination with topical therapy improved skin pain and was associated with improved QoL in both adults and adolescents with moderate-to-severe AD across all evaluated studies.

The role of Janus kinase signaling in the pathology of atopic dermatitis

Atopic dermatitis (AD) is a heterogeneous, chronic, relapsing, inflammatory skin disease associated with considerable physical, psychological, and economic burden. The pathology of AD includes complex interactions involving abnormalities in immune and skin barrier genes, skin barrier disruption, immune dysregulation, microbiome disturbance, and other environmental factors. Many of the cytokines involved in AD pathology, including IL-4, IL-13, IL-22, IL-31, thymic stromal lymphopoietin, and IFN-γ, signal through the Janus kinase (JAK)-signal transducer and activation of transcription (STAT) pathway. The JAK family includes JAK1, JAK2, JAK3, and tyrosine kinase 2; the STAT family includes STAT1, STAT2, STAT3, STAT4, STAT5A/B, and STAT6. Activation of the JAK-STAT pathway has been implicated in the pathology of several immune-mediated inflammatory diseases, including AD. However, the exact mechanisms of JAK-STAT involvement in AD have not been fully characterized. This review aims to discuss current knowledge about the role of the JAK-STAT signaling pathway and, specifically, the role of JAK1 in the pathology and symptomology of AD.

Clinical Management of Neuropathic Itch

This JAMA Network Insight reviews the underlying mechanisms and management of peripheral sensory itch conditions.

Upadacitinib treatment withdrawal and retreatment in patients with moderate-to-severe atopic dermatitis: Results from a phase 2b, randomized, controlled trial

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritic eczematous lesions. The effect of treatment withdrawal after response to upadacitinib oral treatment is not fully characterized.

OBJECTIVES

Assess the effect of upadacitinib withdrawal on skin clearance and itch improvement in adult patients with moderate-to-severe AD and evaluate the kinetics of recovery on rescue treatment.

METHODS

Data from a phase 2b randomized, placebo-controlled trial (NCT02925117) of upadacitinib in patients with moderate-to-severe AD were analysed. Patients were randomized 1:1:1:1 to receive upadacitinib 7.5 mg, 15 mg, 30 mg or placebo, and then at Week 16, patients were re-randomized 1:1 to receive the same dose of upadacitinib (upadacitinib 30 mg for patients initialized to placebo) or placebo. From Week 20, those who experienced loss of response defined as Eczema Area and Severity Index <50% improvement from baseline (EASI 50) received rescue treatment with upadacitinib 30 mg.

RESULTS

Patients who withdrew from upadacitinib experienced a rapid loss of skin clearance response, while those who switched from placebo to upadacitinib gained response. Loss of skin clearance response occurred within 4 weeks and worsening of itch occurred within 5 days. In patients who originally received placebo or a lower dose of upadacitinib leading to a loss of EASI response, rescue treatment with upadacitinib 30 mg resulted in rapid recovery or improvement of both skin and itch responses; most patients who were re-randomized to placebo achieved EASI 75 and IGA 0/1 by 8 weeks of rescue treatment. No new safety risks were observed.

CONCLUSIONS

Continuous treatment with upadacitinib is suggested to maintain skin clearance and antipruritic effects.

Emerging concepts in neuropathic and neurogenic itch

Chronic pruritus has multiple etiologies, ranging from inflammatory to metabolic and neuropathic processes. However, recent advances in itch biology have shed light on potential mechanisms that explain the molecular and cellular basis of these pathologies. Furthermore, new understanding of neuroimmune itch circuits necessitates clarification of terminologies such as "neuropathic" and "neurogenic." This review provides an overview of ways new concepts may better explain the pathophysiology of a variety of chronic pruritic disorders and the rationale for directing emerging novel therapeutic strategies toward them.

Dynamic Fixation versus Static Screw Fixation for Syndesmosis Injuries in Pronation External Rotation Ankle Fractures: A Retrospective Case Control Study

Introduction

The current standard treatment for ankle syndesmosis injury is static screw fixation. Dynamic fixation was developed to restore the dynamic function of the syndesmosis. The purpose of this study was to determine that which of static screw fixation and dynamic fixation is better for treatment of ankle syndesmosis injury in pronation-external rotation fractures.

Materials and methods

Thirty patients were treated with dynamic fixation (DF group) and 28 patients with static screw fixation (SF group). The primary outcome was Olerud-Molander Ankle Outcome Score. The secondary outcome were Visual Analogue Scale score and American Orthopedic Foot and Ankle Society score, radiographic outcomes, complications and cost effectiveness. To evaluate the radiographic outcome, the tibiofibular clear space, tibiofibular overlap, and medial clear space were compared using the pre-operative and last follow-up plain radiographs. To evaluate the cost effectiveness, the total hospital cost was compared between the two groups.

Results

There was no significant difference in primary outcome. Moreover, there were no significant difference in secondary outcome including Visual Analogue Scale score and American Orthopedic Foot and Ankle Society score and radiographic outcome. Two cases of reduction loss and four cases of screw breakage were observed in the SF group. No complication in the DF group was observed. Dynamic fixation was more cost effective than static screw fixation with respect to the total hospital cost.

Conclusion

Although dynamic fixation provided similar clinical and radiologic outcome, dynamic fixation is more cost effective with fewer complications than static screw fixation in ankle syndesmosis injury of pronation-external rotation fractures.

Oral difelikefalin reduces moderate to severe pruritus and expression of pruritic and inflammatory biomarkers in subjects with atopic dermatitis

BACKGROUND

Pruritus is the most common and burdensome symptom of atopic dermatitis (AD). Pruritus-targeted treatments in AD are lacking, particularly for patients with milder skin disease.

OBJECTIVE

We sought to evaluate the impact of the selective κ-opioid receptor agonist difelikefalin (DFK) on pruritus intensity and pruritus- and immune-related biomarkers in subjects with moderate to severe AD-related pruritus.

METHODS

A phase 2 clinical trial investigated the efficacy and safety of oral DFK 0.25, 0.5, and 1.0 mg in subjects with moderate to severe AD-related pruritus. A biomarker substudy evaluated the effects of DFK on the expression of pruritus, TH2-associated genes, and skin barrier-related genes.

RESULTS

In the clinical trial (N = 401), all DFK doses reduced itch versus placebo; however, the results were not statistically significant at week 12. In a subgroup of subjects in the trial with mild to moderate skin inflammation and moderate to severe itch (itch-dominant AD phenotype), DFK reduced itch at week 12 versus placebo. In the biomarker substudy, DFK downregulated the expression of key pruritus-related genes (eg, IL-31 and TRPV1) and the AD phenotype (eg, CCL17). Gene set variation analysis confirmed that DFK, but not placebo, downregulated pruritus-related genes and TH2 pathways. DFK improved skin barrier integrity markers and upregulated the expression of claudins and lipid metabolism-associated genes (eg, SEC14L6, ELOVL3, CYP1A2, and AKR1D1).

CONCLUSIONS

DFK treatment reduced itch in subjects with moderate to severe AD-related pruritus, particularly those with an "itch-dominant" AD phenotype, and had an impact on the expression of pruritus, TH2-associated genes, and skin barrier-related genes. DFK is a promising therapy for AD-related pruritus; further clinical studies are warranted.

Difelikefalin suppresses itch and reduces scratching independent of inflammation in a murine model of atopic dermatitis

BACKGROUND

Therapies specifically targeting nonhistaminergic pruritus are largely lacking. Difelikefalin (DFK) has been found to reduce itch in various chronic pruritic conditions, including atopic dermatitis (AD).

OBJECTIVE

We sought to investigate the ability of DFK to impact scratching behavior, inflammatory mediators, and neuronal signaling in a murine model of AD.

METHODS

The ears of C57BL/6 mice were topically treated with MC903 for 12 consecutive days to induce AD-like inflammation and itch. Before MC903 treatment, mice were treated with either DFK (0.5 mg/kg, intraperitoneal injection twice daily) or vehicle (saline). Skin ear thickness, histological analysis, flow cytometry, RNA-sequencing, and differential gene expression analyses of mouse ear skin were used to examine the effect of DFK on skin inflammation. Scratching behavior was quantified to measure itch behavior in mice that were topically treated with MC903 for 6 consecutive days; then, mice received a single injection of either DFK (1.0 mg/kg, intraperitoneal injection) or saline. Calcium imaging and single-cell RNA-sequencing were used in mouse dorsal root ganglia neurons to determine the size of the neurons activated with DFK treatment. Statistical significance was determined by Mann-Whitney test, unless otherwise noted.

RESULTS

DFK rapidly suppressed itch without altering AD-like skin inflammation in MC903 (calcipotriol)-treated mice. In vitro Ca2+ influx trace of dorsal root ganglia suggested that a major target for DFK is the larger-diameter mechanoreceptors (eg, Aꞵ-fibers), rather than small-diameter pruriceptive C-fibers.

CONCLUSIONS

These studies support a potential neuromodulatory role of DFK for reducing itch associated with AD in mice.

Arthroscopic Suprapectoral Biceps Tenodesis Using Standard Portals

The long head of the biceps (LHB) tendon is a common cause of shoulder pain. Biceps tenodesis is commonly used to address biceps and superior labrum pathology, reducing pain and restoring function. There are numerous techniques for biceps tenodesis, and it is unclear as to which single technique and approach provides significantly superior outcomes. In this technical note, we present an arthroscopic suprapectoral approach with release of the LHB from the bicipital groove and subsequent fixation with suture anchor. This technique simplifies the technique to be performed from standard arthroscopic portals and aims to maximize outcomes and minimize common complications associated with biceps tenodesis.

Dupilumab in patients with prurigo nodularis: two randomized, double-blind, placebo-controlled phase 3 trials

Prurigo nodularis (PN) is a chronic inflammatory skin disease with intensely pruritic nodules. The LIBERTY-PN PRIME and PRIME2 phase 3 trials enrolled adults with PN with ≥20 nodules and severe itch uncontrolled with topical therapies. Dupilumab, a fully human monoclonal antibody, blocks the shared receptor component for interleukin (IL)-4 and IL-13. Patients were randomized 1:1 to 300 mg dupilumab or placebo subcutaneously every 2 weeks for 24 weeks. The primary endpoint was pruritus improvement, measured by proportion of patients with a ≥4-point reduction in Worst Itch Numeric Rating Scale (WI-NRS) from baseline at week 24 (PRIME) or week 12 (PRIME2). Key secondary endpoints included nodule number reduction to ≤5 at week 24. PRIME and PRIME2 enrolled 151 and 160 patients, respectively. Both trials met all the pre-specified primary and key secondary endpoints. A ≥4-point WI-NRS reduction at week 24 in the dupilumab and placebo arms was achieved by 60.0% and 18.4% of patients, respectively, in PRIME (95% confidence interval (CI), 27.8-57.7 for the difference, P < 0.001) and at week 12 by 37.2% and 22.0% of patients, respectively, in PRIME2 (95% CI, 2.3-31.2; P = 0.022). Dupilumab demonstrated clinically meaningful and statistically significant improvements in itch and skin lesions versus placebo in PN. Safety was consistent with the known dupilumab safety profile.ClinicalTrials.gov identifiers: NCT04183335 and NCT04202679 .

MrgprA3-expressing pruriceptors drive pruritogen-induced alloknesis through mechanosensitive Piezo2 channel

Although touch and itch are coded by distinct neuronal populations, light touch also provokes itch in the presence of exogenous pruritogens, resulting in a phenomenon called alloknesis. However, the cellular and molecular mechanisms underlying the initiation of pruritogen-induced mechanical itch sensitization are poorly understood. Here, we show that intradermal injections of histamine or chloroquine (CQ) provoke alloknesis through activation of TRPV1- and MrgprA3-expressing prurioceptors, and functional ablation of these neurons reverses pruritogen-induced alloknesis. Moreover, genetic ablation of mechanosensitive Piezo2 channel function from MrgprA3-expressing prurioceptors also dampens pruritogen-induced alloknesis. Mechanistically, histamine and CQ sensitize Piezo2 channel function, at least in part, through activation of the phospholipase C (PLC) and protein kinase C-δ (PKCδ) signaling. Collectively, our data find a TRPV1+/MrgprA3+ prurioceptor-Piezo2 signaling axis in the initiation of pruritogen-induced mechanical itch sensitization in the skin.

Burden of Disease and Unmet Needs in Atopic Dermatitis: Results From a Patient Survey

Background: Atopic dermatitis (AD) affects 2%-10% of adults worldwide. Occurrence and severity of symptoms and treatment success vary among patients. Objective: To determine disease severity, burden, and treatment use and satisfaction in adults with AD. Methods: An international internet-based survey was conducted (October 5-November 1, 2021) in participants with AD from Canada, France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States. Results: Of 2005 AD patients surveyed, 92% had body surface area (BSA) involvement <10%. Itch was the most bothersome symptom; 48.5% of participants reported severe itch in the past week (Itch Numerical Rating Scale [NRS] 7-10; 45.9% for BSA <10%, 75.0% for BSA ≥10%). Most participants reported moderate or severe sleep disturbance in the past week (Sleep NRS 4-10; 67.1% for BSA <10%, 92.3% for BSA ≥10%). Itch was the top reason for participants' most recent health care provider visit; reducing itching was their top treatment goal. Topical therapies, which were most commonly used, resulted in low treatment satisfaction. Conclusions: Itch was the most bothersome AD symptom. Although clinical development has focused on improving skin lesions, improving itch is patients' top treatment goal. This survey highlights the need for systemic antipruritic therapies that could reduce itch in nonlesional and lesional skin.

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.).

Association of KIR2DL5, KIR2DS5, and KIR2DS1 allelic variation and atopic dermatitis

Natural killer cells (NK) have been associated with the pathophysiology of atopic dermatitis (AD). NK function is regulated by killer cell Ig-like receptor family (KIR) receptors that interact with HLA ligands. The study goal was to focus on allelic variation in genes KIR2DL5, KIR2DS5, and KIR2DS1 with respect to AD. This was a case-control study of individuals with (n = 313) and without (n = 176) AD. Associations were estimated using logistic regression. The prevalence of KIR2DL5 was 52.5% (95% CI 48.0,57.0), KIR2DS5 was 33.0% (28.8,37.3), and KIR2DS1 was 33.6% (29.4,38.0). The presence of the KIR2DL5*001:01 increased the odds of having AD by about 86% (odds ratio (OR): 1.86(1.23,2.82) p = 0.003). The risk for individuals homozygous for KIR2DL5*001:01 was even greater (OR: 2.16 (95% CI 1.31,3.53) p = 0.0023). The odds of having AD with KIR2DL5*001:01 was similar in Whites and Blacks. Allelic variation in KIR2DS5 and KIR2DS1 was not associated with AD. There is no known HLA binding ligand for KIR2DL5. The effect of KIR2DL5*001:01 increased in the presence of HLA-B*-21TT leader sequence (2.46(1.37,4.41) p = 0.0025) and the HLA-C2 ligand (2.07 (1.37,4.41, p = 0.000002). Our study shows an independent association of the KIR2DL5*001:01 with AD and is the first study to associate AD with KIR allelic variation.

350 Examining the relationships among abrocitinib treatment, itch, skin pain and work and activity impairments in patients with atopic dermatitis: a mediation modelling analysis

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by intense itch, skin pain and impaired quality of life. Skin pain is a common and bothersome symptom of AD and increases in prevalence and intensity with worsening disease severity. Abrocitinib is an oral, once-daily, selective Janus kinase-1 inhibitor approved for the treatment of moderate-to-severe AD. Abrocitinib treatment resulted in improvements in skin clearance as well as rapid itch reduction in patients with moderate-to-severe AD across multiple phase 3 studies. Work productivity loss and activity impairment were assessed in the phase 3 JADE MONO-2 (NCT03575871) trial, with greater improvements being associated with abrocitinib treatment compared with placebo. The mechanism(s) through which abrocitinib reduces work productivity loss and activity impairment are unclear. To describe the interrelationships among abrocitinib treatment, itch, skin pain, and work productivity and activity impairment using a mediation modelling analysis in patients with AD. Data from adult patients treated with abrocitinib monotherapy (200 or 100 mg) or placebo in JADE MONO-2 were included in this analysis. As separate outcomes, work productivity loss and activity impairment (outcome variables) were measured by the Work Productivity and Activity Impairment Questionnaire: Atopic Dermatitis version 2.0 (WPAI-AD 2.0). Itch and skin pain (mediator variables) were evaluated using the Pruritus and Symptoms Assessment for Atopic Dermatitis (PSAAD) item #1 (How itchy was your skin over the past 24 h?) and item #2 (How painful was your skin over the past 24 h?), respectively. Mediation modelling was conducted independently for work productivity loss and activity impairment. All available data at week 12 were used in the modelling. Effects with P &lt; 0.05 were considered statistically significant. The direct effects of abrocitinib were estimated to be 7.3% (P = 0.779) and 17.5% (P = 0.258) on work productivity loss and activity impairment, respectively. The indirect effects of abrocitinib treatment on work productivity loss and, separately, on activity impairment mediated via itch were estimated to be 50.6% (P = 0.017) and 20.9% (P = 0.062), respectively, and via skin, pain were estimated to be 42.1% and 61.5%, respectively, (P &lt; 0.05 for both). The indirect effect of abrocitinib treatment on work productivity loss is mediated approximately equally through the reduction in itch severity and skin pain. The effect of abrocitinib treatment on activity impairment is mostly mediated indirectly through the reduction of skin pain, along with a smaller indirect contribution from the reduction in itch. These findings support further research into the extent that patients consider itch and skin pain as separate concepts in terms of their impact on work productivity.

351 Examining the relationships among abrocitinib treatment, itch, skin pain and dermatology-specific quality of life in patients with atopic dermatitis: a mediation modelling analysis

Atopic dermatitis (AD) is a chronic inflammatory skin disease associated with itch, eczematous lesions and impaired quality of life (QoL). Although the frequency of skin pain in AD is often underestimated, it is associated with a substantial health burden, similar to itch and is known to contribute to sleep disruption and mood disturbance. Abrocitinib is an oral, once-daily, selective Janus kinase-1 inhibitor approved for the treatment of moderate-to-severe AD. In phase 3 clinical trials JADE MONO-1 (NCT03349060) and JADE MONO-2 (NCT03575871), abrocitinib demonstrated rapid relief from itch and skin pain, as well as meaningful improvements in QoL compared with placebo. The interrelationships between abrocitinib treatment and improvements in itch, skin pain and QoL have not yet been investigated. This mediation analysis aimed to characterize the effect of abrocitinib treatment via itch and skin pain on dermatology-specific QoL in patients with AD. Data from JADE MONO-1 and JADE MONO-2 were pooled in this analysis. Adult patients with moderate-to-severe AD received abrocitinib (200 or 100 mg) as monotherapy or placebo for 12 weeks. Three separate models were evaluated whereby QoL was assessed using the Dermatology Life Quality Index (DLQI) score, and itch and skin pain were assessed via the Pruritus and Symptoms Assessment for Atopic Dermatitis (PSAAD) items #1 (How itchy was your skin over the past 24 h?) and #2 (How painful was your skin over the past 24 h?), respectively. The cross-sectional mediation model (CSMM) was run separately at weeks 2, 4, 8 and 12 using all available data at each timepoint. The longitudinal mediation model (LMM), which does not assume independence among measurements of itch, skin pain and DLQI at each timepoint, estimated relationships using all available data from all weeks simultaneously. Based on the results of the CSMM and LMM, a pseudo-steady-state model, in which the relationship among variables was assumed to be the same across timepoints, was applied. Effects with P &lt; 0.05 were considered statistically significant. In the CSMM, the indirect effect of abrocitinib on DLQI mediated via itch was considered approximately stable (24–30%) for the first 8 weeks before increasing at week 12 (42%), while the indirect effect mediated via skin pain was considered approximately stable from week 2 to week 12 (33–41%). In the LMM, the indirect effect of abrocitinib treatment on DLQI mediated via both itch and skin pain was considered approximately stable from week 2 to week 12 (17–26% and 42–48%, respectively). The cross-sectional and longitudinal models were generally consistent and indicated a pseudo-steady-state period between weeks 2 and 12. Using the pseudo-steady-state model, the direct effect of abrocitinib on DLQI was estimated to be 34.8% (P &lt; 0.0001), and the indirect effects mediated via itch and skin pain were estimated to be 19.5% and 45.8%, respectively (P ≤ 0.0001 for both). Improvements in dermatology-specific QoL with abrocitinib are mostly mediated indirectly via a reduction in skin pain and less so by relief of itch. These findings warrant further research to examine to what extent patients consider itch and skin pain as separate concepts in terms of their impact on dermatology-specific QoL.

341 Dupilumab improves itch and skin lesions in adults with prurigo nodularis regardless of prior use of immunosuppressants or phototherapy: post-hoc results from PRIME and PRIME2 clinical trials

Dupilumab is the only FDA-approved systemic therapy for prurigo nodularis (PN), however, immunosuppressants (IS) and phototherapy have been used off-label for the treatment of this condition. Patients with prior IS/phototherapy treatment may represent a more severe and/or treatment-refractory population of patients with PN. Report post-hoc efficacy of dupilumab in patients with PN, with or without prior use of IS or phototherapy for PN. LIBERTY-PN PRIME and PRIME2 (NCT04183335 and NCT04202679) are randomized, 24-week, phase 3 studies in adults with PN that is inadequately controlled by topical prescription therapies or for whom those therapies are not advisable. Primary outcomes included a ≥4-point improvement in the weekly average of Worst Itch Numerical Rating Scale (WI-NRS) from baseline to week 24, and an Investigator’s Global Assessment for PN stage (IGA PN-S) score of 0/1 (clear/almost clear) at week 24. Safety outcomes included the incidence of treatment-emergent adverse events (TEAEs). Among patients with PN, 8.0% reported prior use of phototherapy, and 36.7% reported prior use of IS; overall, 126 (dupilumab group, n = 62; placebo group, n = 64) patients with and 185 (dupilumab, n = 91; placebo, n = 94) patients without prior IS/phototherapy use were included. A larger proportion of patients with prior treatment vs. patients without prior treatment had severe disease, as measured by IGA PN-S (40.5% vs. 29.0%). The baseline WI-NRS score (SD) for overall patients with prior treatment was 8.6 (1.0) and for patients without prior treatment was 8.4 (1.0). At week 24, 67.7% vs. 15.6% of patients in the dupilumab vs. placebo groups with prior treatment (odds ratio [95% confidence interval]: 13.6 [3.7–49.7]; P &lt; 0.0001), and 52.7% vs. 21.3% of patients without prior treatment (5.8 [2.4–14.0]; P &lt; 0.0001) achieved improvement in WI-NRS. Similarly, 35.5% vs. 10.9% (3.1 [1.2–8.4]; P = 0.0162) of patients with and 53.8% vs. 21.3% (5.0 [2.3–10.8]; P &lt; 0.0001) of those without prior treatment achieved IGA PN-S score of 0/1, respectively. TEAEs were reported by 43 (69.4%) vs. 34 (53.1%) patients (dupilumab vs. placebo groups) with and 54 (60.0%) vs. 55 (59.1%) without prior treatment, respectively. Patients treated with dupilumab experienced a greater and clinically meaningful improvement in itch and achieved skin that was clear/almost clear of nodules at week 24, regardless of prior use of IS/phototherapy for the treatment of PN. The incidence of TEAEs was generally consistent among patients with and without prior IS/phototherapy.

Rapid pruritus reduction with ruxolitinib cream treatment in patients with atopic dermatitis

BACKGROUND

Ruxolitinib cream is a topical formulation of ruxolitinib, a Janus kinase (JAK) 1/JAK2 inhibitor.

OBJECTIVES

To report timing and magnitude of effect of ruxolitinib cream on itch in patients with atopic dermatitis (AD), a highly pruritic inflammatory skin disease.

METHODS

Two phase 3 trials (TRuE-AD1 [NCT03745638]/TRuE-AD2 [NCT03745651]) enrolled patients aged ≥12 years with AD for ≥2 years, Investigator's Global Assessment score of 2 or 3, and 3%-20% affected body surface area. Patients (total N = 1249; median age, 32 years) were randomised (2:2:1) to twice daily 0.75% ruxolitinib cream, 1.5% ruxolitinib cream or vehicle cream for 8 weeks of double-blinded treatment. Worst itch was measured using the numerical rating scale (NRS).

RESULTS

Significantly more patients who applied ruxolitinib cream (either strength) achieved a ≥2-point itch reduction (NRS2) within approximately 12 h versus vehicle (0.75%/1.5% ruxolitinib cream, 16.3%/13.1%; vehicle, 6.9%; both P < 0.05), with further improvements through Week 8 (58.3%/65.1% vs 29.4%; both P < 0.0001). A ≥4-point itch reduction (NRS4) was achieved by significantly more patients who applied 0.75%/1.5% ruxolitinib cream versus vehicle by Day 2 (8.9%/11.2% vs 2.1%; P < 0.005); higher rates were observed at Week 8 (41.5%/51.5% vs 15.8%; P < 0.0001). Median time for the 0.75%/1.5% ruxolitinib cream groups to achieve NRS4 from baseline was 15.0/13.0 days; this endpoint was not reached by the vehicle group.

CONCLUSIONS

Ruxolitinib cream demonstrated rapid improvement in itch in patients with mild to moderate AD that was sustained for 8 weeks. Significantly more patients applying ruxolitinib cream achieved itch NRS2 within approximately 12 h and itch NRS4 by Day 2 versus vehicle.

Skin-homing basophils and beyond

Basophils have been implicated in type 2 inflammation and numerous disorders in the skin such as helminth infection, atopic dermatitis, and urticaria. Although similar in form and function to tissue-resident mast cells, classical studies on basophils have centered on those from the hematopoietic compartment. However, increasing studies in tissues like the skin demonstrate that basophils may take on particular characteristics by responding to unique developmental, chemotactic, and activation cues. Herein, we highlight how recent studies in barrier immunology suggest the presence of skin-homing basophils that harbor a unique identity in terms of phenotype, function, and motility. These concepts may uniquely inform how basophils contribute to diseases at multiple epithelial surfaces and our ability to therapeutically target the innate immune system in disease.

Role of kappa-opioid and mu-opioid receptors in pruritus: Peripheral and central itch circuits

Modern genetic approaches in animal models have unveiled novel itch-specific neural pathways, emboldening a paradigm in which drugs can be developed to selectively and potently target itch in a variety of chronic pruritic conditions. In recent years, kappa-opioid receptors (KORs) and mu-opioid receptors (MORs) have been implicated in both the suppression and promotion of itch, respectively, by acting on both the peripheral and central nervous systems. The precise mechanisms by which agents that modulate these pathways alleviate itch remains an active area of investigation. Notwithstanding this, a number of agents have demonstrated efficacy in clinical trials that influence both KOR and MOR signalling. Herein, we summarize a number of opioid receptor modulators in development and their promising efficacy across a number of chronic pruritic conditions, such as atopic dermatitis, uremic pruritus and beyond.

Insights into atopic dermatitis pathogenesis lead to newly approved systemic therapies

Atopic dermatitis (AD) is a common inflammatory skin disease characterized by scaly, oozing skin and itch. In moderate-to-severe AD, treatment options have been historically very limited and off-label use has been a common method for disease management. For decades, ciclosporin A was the only systemic immunosuppressive drug approved in most European countries to address this major unmet medical need. However, increased understanding of the pathophysiology of AD has led to a revolution in the treatment of this potentially debilitating disease. Following the approval of the first biological therapy for AD in 2017, there has been a rapid expansion of compounds under development and four additional systemic therapies have been approved in Europe and the USA within the past 3 years alone. In this review, we underscore how key breakthroughs have transformed the therapeutic landscape of AD, leading to a major expansion of type 2 immunity-targeted biological therapies, exploration of neuroimmune modulatory agents, and interest in Janus kinase inhibition.

Augmented risk of ischemic stroke in hypertrophic cardiomyopathy patients without documented atrial fibrillation

Background

Ischemic stroke is a common complication in patients with hypertrophic cardiomyopathy (HCM) (1). Although atrial fibrillation (AF) is a well-established risk factor for ischemic stroke in HCM, the risk of ischemic stroke in patients with HCM without documented AF is less recognized (1, 2). This study aimed to determine the risk of ischemic stroke and identify its risk factors in patients with HCM without documented AF.

Methods

This nationwide population-based cohort study used the Korean National Health Insurance database. After excluding patients with a prior history of AF, thromboembolic events, cancer, or the use of anticoagulants, we identified 8,328 HCM patients without documented AF and 1:2 propensity score-matched 16,656 non-HCM controls. The clinical outcome was an incident ischemic stroke.

Results

During a mean follow-up of approximately 6 years, ischemic stroke occurred in 328/8,328 (3.9%) patients with HCM and 443/16,656 (2.7%) controls. Among individuals who developed ischemic stroke, the proportion of AF concomitantly detected accounted for 26.5% (87/328) and 5.8% (26/443) in the HCM and control groups, respectively. The overall incidence of ischemic stroke was 0.716/100 person-years in the HCM group, which was significantly higher than that in the control group (0.44/100 person-years) (HR 1.643; 95% CI, 1.424–1.895; P&lt;0.001, Figure 1). The subgroup analysis according to age, sex, and comorbidities (chronic heart failure, hypertension, dyslipidemia, and vascular disease) consistently demonstrated a higher risk of ischemic stroke in the HCM group (P for interaction &gt;0.05). In the HCM group, age ≥65 years (adjusted hazard ratio [HR] 2.741; 95% confidence interval [CI], 2.156–3.486; P&lt;0.001) and chronic heart failure (adjusted HR 1.748; 95% CI, 1.101–2.745; P=0.018) were independent risk factors for ischemic stroke. Overall incidence was 1.360/100 in patients with HCM aged ≥65 and 2.315/100 person-years years in those with chronic heart failure, respectively. Also, compared to controls aged &lt;65 years and without CHF, adjusted HR for ischemic stroke was 4.756 (95% CI 3.807–5.867) in patients with HCM aged ≥65 years and 2.539 (95% CI 1.638–3.936) in those with CHF, respectively (Figure 2).

Conclusions

Patients with HCM without documented AF are at a higher risk of ischemic stroke than the propensity score-matched general population. Age ≥65 years and chronic heart failure are two strong independent risk factors for ischemic stroke in this population.

Funding Acknowledgement

Type of funding sources: None.

Impact of estimated pulse wave velocity on cardiovascular outcomes in a general population

Background

Estimated pulse wave velocity (ePWV), a simple surrogate estimate of carotid-femoral pulse wave velocity which was gold standard for measuring aortic stiffness, has been demonstrated to predict cardiovascular (CV) outcome. However, there was limited data on its predictive capacity for CV outcomes in the general population. The study aim was to investigate the independent association between ePWV and CV outcomes in general population.

Methods

A total of 10,030 subjects aged between 40 and 69 years were followed over 18-year period in the Ansan-Ansung cohort study. Levels of ePWV, which was calculated from an equation based on age and mean blood pressure, were categorized according to quartiles. A major adverse cardiovascular event (MACE) was defined as a composite of myocardial infarction, coronary artery disease, stroke, heart failure, peripheral artery disease, and cardiovascular death.

Results

The incidence rates of CV death, and MACE were 7.0% and 22.1% in the fourth (highest) quartile of ePWV and 0.1% and 4.5% in the first (lowest) quartile of ePWV. After adjusting for relevant covariates, patients with third and fourth quartile of ePWV showed significantly higher risk of CV death (hazard ratio [HR] 3.92; 95% confidence intervals [CI] 1.09–14.15 in third quartile and HR 8.53; 95% CI 2.13–34.10 in fourth quartile), and MACE (HR 1.54; 95% CI 1.15–2.08 in third quartile and HR 1.56; 95% CI 1.05–2.32) compared to the reference of first (lowest) quartile of ePWV. However, there were no improvement of C statistic for CV death and MACE when adding ePWV to the Cox regression models with 10-year atherosclerotic cardiovascular disease (ASCVD) risk.

Conclusion

These results suggest that ePWV predicted CV death and MACE in general population. The value of ePWV, a simple and useful indicator of aortic stiffness, is expected to serve as a potential marker to identify high risk groups of CV event in general population.

Funding Acknowledgement

Type of funding sources: None.

Influence of concomitant percutaneous transluminal angioplasty with percutaneous coronary intervention on outcomes in patients with stable lower extremity artery disease

Background

Patients with stable lower extremity artery diseases (LEAD) frequently present with coronary artery diseases; thus, concomitant percutaneous transluminal angioplasty (PTA) at the time of percutaneous coronary intervention (PCI) is often performed. We investigated the influence of concomitant PTA on both cardiovascular (CV) and limb outcomes in the Korean National Health Insurance Service registry.

Methods

Among 78,185 patients undergoing PCI between 2012 and 2015, 6,563 patients (279 for the PTA+PCI group vs. 6,284 for the PCI group) suffering from stable LEAD without limb ischemia were included. Major adverse CV events (MACEs) were defined as a composite of CV death, myocardial infarction (MI) and coronary revascularization. Patients were followed for at least 3 years.

Results

After 1:5 propensity score matching was conducted, 279 patients in the PTA+PCI group and 1,385 patients in the PCI group were compared. The risk of all-cause death was higher in the PTA+PCI group than in the PCI group, whereas the risks of MACE, MI, revascularization, stroke, CV death and bleeding event were not different between the 2 groups in the matched cohort. In contrast, the risks of end-stage renal diseases and unfavorable limb outcomes were higher in the PTA+PCI group than in the PCI group (Figure 1). Mediation analyses revealed that amputation and repeat Percutaneous transluminal angioplasty after discharge significantly mediated the association between the concomitant PTA and all-cause death (Figure 2).

Conclusions

CPTA at the time of PCI is not associated with an increased risk of CV events but may increase the risk of all-cause death by increasing unfavorable renal and limb outcomes in patients with stable LEAD.

Funding Acknowledgement

Type of funding sources: None.

Keratinocyte-derived defensins activate neutrophil-specific receptors Mrgpra2a/b to prevent skin dysbiosis and bacterial infection

Healthy skin maintains a diverse microbiome and a potent immune system to fight off infections. Here, we discovered that the epithelial-cell-derived antimicrobial peptides defensins activated orphan G-protein-coupled receptors (GPCRs) Mrgpra2a/b on neutrophils. This signaling axis was required for effective neutrophil-mediated skin immunity and microbiome homeostasis. We generated mutant mouse lines lacking the entire Defensin (Def) gene cluster in keratinocytes or Mrgpra2a/b. Def and Mrgpra2 mutant animals both exhibited skin dysbiosis, with reduced microbial diversity and expansion of Staphylococcus species. Defensins and Mrgpra2 were critical for combating S. aureus infections and the formation of neutrophil abscesses, a hallmark of antibacterial immunity. Activation of Mrgpra2 by defensin triggered neutrophil release of IL-1β and CXCL2 which are vital for proper amplification and propagation of the antibacterial immune response. This study demonstrated the importance of epithelial-neutrophil signaling via the defensin-Mrgpra2 axis in maintaining healthy skin ecology and promoting antibacterial host defense.

Miswiring of Merkel cell and pruriceptive C fiber drives the itch-scratch cycle

Itch sensation provokes the scratch reflex to protect us from harmful stimuli in the skin. Although scratching transiently relieves acute itch through activation of mechanoreceptors, it propagates the vicious itch-scratch cycle in chronic itch by further aggravating itch over time. Although well recognized clinically, the peripheral mechanisms underlying the itch-scratch cycle remain poorly understood. Here, we show that mechanical stimulation of the skin results in activation of the Piezo2 channels on Merkel cells that pathologically promotes spontaneous itch in experimental dry skin. Three-dimensional reconstruction and immunoelectron microscopy revealed structural alteration of MRGPRA3⁺ pruriceptor nerve endings directed toward Merkel cells in the setting of dry skin. Our results uncover a functional miswiring mechanism under pathologic conditions, resulting in touch receptors triggering the firing of pruriceptors in the skin to drive the itch-scratch cycle.

The translational revolution of itch

The ability to sense the environment is essential to survival and is the primary purpose of the somatosensory nervous system. However, despite its highly conserved nature, the sensation of itch has been historically overlooked, and its importance in medicine underappreciated. Herein, we highlight how fundamental discoveries, coupled to rapid successes of new therapeutics, have placed itch biology at the forefront of a translational revolution in the field of somatosensation and beyond.

Nanoscale lattice dynamics in hexagonal boron nitride moiré superlattices

Twisted two-dimensional van der Waals (vdW) heterostructures have unlocked a new means for manipulating the properties of quantum materials. The resulting mesoscopic moiré superlattices are accessible to a wide variety of scanning probes. To date, spatially-resolved techniques have prioritized electronic structure visualization, with lattice response experiments only in their infancy. Here, we therefore investigate lattice dynamics in twisted layers of hexagonal boron nitride (hBN), formed by a minute twist angle between two hBN monolayers assembled on a graphite substrate. Nano-infrared (nano-IR) spectroscopy reveals systematic variations of the in-plane optical phonon frequencies amongst the triangular domains and domain walls in the hBN moiré superlattices. Our first-principles calculations unveil a local and stacking-dependent interaction with the underlying graphite, prompting symmetry-breaking between the otherwise identical neighboring moiré domains of twisted hBN.

Here, the authors investigate the lattice dynamics of twisted hexagonal boron nitride layers via nano-infrared spectroscopy, showing local and stacking-dependent variations of the optical phonon frequencies associated to the interaction with the graphite substrate.

IL-33 signaling in sensory neurons promotes dry skin itch

BACKGROUND

Chronic pruritus, or itch, is common and debilitating, but the neuroimmune mechanisms that drive chronic itch are only starting to be elucidated. Recent studies demonstrate that the IL-33 receptor (IL-33R) is expressed by sensory neurons. However, whether sensory neuron-restricted activity of IL-33 is necessary for chronic itch remains poorly understood.

OBJECTIVES

We sought to determine if IL-33 signaling in sensory neurons is critical for the development of chronic itch in 2 divergent pruritic disease models.

METHODS

Plasma levels of IL-33 were assessed in patients with atopic dermatitis (AD) and chronic pruritus of unknown origin (CPUO). Mice were generated to conditionally delete IL-33R from sensory neurons. The contribution of neuronal IL-33R signaling to chronic itch development was tested in mouse models that recapitulate key pathologic features of AD and CPUO, respectively.

RESULTS

IL-33 was elevated in both AD and CPUO as well as their respective mouse models. While neuron-restricted IL-33R signaling was dispensable for itch in AD-like disease, it was required for the development of dry skin itch in a mouse model that mirrors key aspects of CPUO pathology.

CONCLUSIONS

These data highlight how IL-33 may be a predominant mediator of itch in certain contexts, depending on the tissue microenvironment. Further, this study provides insight into future therapeutic strategies targeting the IL-33 pathway for chronic itch.

Association of KIR Genes and MHC Class I Ligands with Atopic Dermatitis

Atopic dermatitis (AD) is a chronic illness that is associated with immune dysregulation. NK cell function has previously been associated with AD. NK cells directly interact with polymorphic HLA class I ligand variants using killer cell Ig-like receptors (KIRs). The purpose of this study was to identify potential associations between NK cell function and AD by evaluating variation in the presence of KIR genes as well as KIR gene interactions with the appropriate HLA class I KIR-specific ligands. Human DNA from the genetics of AD case-control study was used to genotype HLA class I KIR-specific ligands and the presence of KIR genes. In the full cohort, an increased risk of AD was noted for KIR2DL5 (1.51 [1.13, 2.01]), KIR2DS5 (1.72 [1.26, 2.34]), and KIR2DS1 (1.41 [1.04, 1.91]). Individuals with KIR2DS5 or KIR2DS1 and the HLA-C*C2 epitope were at an increased risk of AD (1.74 [1.21, 2.51] and 1.48 [1.04, 2.12], respectively). The HLA-B*-21T (TT) leader sequence increased the risk of AD across ethnicity. African Americans with KIR2DL2, KIR2DS1, KIR2DL5, and KIR2DS5 are more likely to have AD, and the risk increased for KIR2DS1 and KIR2DS5 in the presence of appropriate HLA-C C2 epitope. The risk of AD also increased for individuals with the HLA-B*-21T leader sequence. Future studies should focus on KIR gene allelic variation as well as consider cell-based measurements of KIR and the associated HLA class I epitopes.

Human leukocyte antigen class-I variation is associated with atopic dermatitis: A case-control study

Atopic dermatitis (AD) is a common immune-medicated skin disease. Previous studies have explored the relationship between Human Leukocyte Antigen (HLA) allelic variation and AD with conflicting results. The aim was to examine HLA Class I genetic variation, specifically peptide binding groove variation, and associations with AD. A case-control study was designed to evaluate HLA class I allelic variation and binding pocket polymorphisms, using next generation sequencing on 464 subjects with AD and 388 without AD. Logistic regression was used to evaluate associations with AD by estimating odds ratios (95% confidence intervals). Significant associations were noted with susceptibility to AD (B*53:01) and protection from AD (A*01:01, A*02:01, B*07:02 and C*07:02). Evaluation of polymorphic residues in Class I binding pockets revealed six amino acid residues conferring protection against AD: A9F (HLA-A, position 9, phenylalanine) [pocket B/C], A97I [pocket C/E], A152V [pocket E], A156R [pocket D/E], B163E [pocket A] and C116S [pocket F]. These findings demonstrate that specific HLA class I components are associated with susceptibility or protection from AD. Individual amino acid residues are relevant to protection from AD and set the foundation for evaluating potential HLA Class I molecules in complex with peptides/antigens that may initiate or interfere with T-cell responses.

Sneezing reflex is mediated by a peptidergic pathway from nose to brainstem

Sneezing is a vital respiratory reflex frequently associated with allergic rhinitis and viral respiratory infections. However, its neural circuit remains largely unknown. A sneeze-evoking region was discovered in both cat and human brainstems, corresponding anatomically to the central recipient zone of nasal sensory neurons. Therefore, we hypothesized that a neuronal population postsynaptic to nasal sensory neurons mediates sneezing in this region. By screening major presynaptic neurotransmitters/neuropeptides released by nasal sensory neurons, we found that neuromedin B (NMB) peptide is essential for signaling sneezing. Ablation of NMB-sensitive postsynaptic neurons in the sneeze-evoking region or deficiency in NMB receptor abolished the sneezing reflex. Remarkably, NMB-sensitive neurons further project to the caudal ventral respiratory group (cVRG). Chemical activation of NMB-sensitive neurons elicits action potentials in cVRG neurons and leads to sneezing behavior. Our study delineates a peptidergic pathway mediating sneezing, providing molecular insights into the sneezing reflex arc.

Antifungal activity of streptavidin C1 and C2 against pathogens causing Fusarium wilt

Fusarium wilt is caused by the soil-inhabiting fungus Fusarium oxysporum ff. spp. and is one of the most devastating plant diseases, resulting in losses and decreasing the quality and safety of agricultural crops. We recently reported the structures and biochemical properties of two biotin-binding proteins, streptavidin C1 and C2 (isolated from Streptomyces cinnamonensis strain KPP02129). In the present study, the potential of the biotin-binding proteins as antifungal agent for Fusarium wilt pathogens was investigated using recombinant streptavidin C1 and C2. The minimum inhibitory concentration of streptavidin C2 was found to be 16 µg ml^-1 for inhibiting the mycelial growth of F. oxysporum f.sp. cucumerinum and F. oxysporum f.sp. lycopersici, while that of streptavidin C1 was found to be 64 µg ml^-1 . Compared with the nontreated control soil, the population density of F. oxysporum f.sp. lycopersici in the soil was reduced to 49·5% and 39·6% on treatment with streptavidin C1 (500 µg ml^-1 ) and C2 (500 µg ml^-1 ), respectively. A greenhouse experiment revealed that Fusarium wilt of tomato plants was completely inhibited on soil drenching using a 50-ml culture filtrate of the streptavidin-producing strain KPP02129.

Innate Immune Regulation of Dermatitis

Dermatitis encompasses a spectrum of inflammatory skin disorders with aberrant immune responses classified as type 1, type 2, and/or type 3. Major advances in the understanding of the pathogenesis of atopic dermatitis (AD) have shed new light on how innate immune responses critically regulate type 2 inflammation and itch. This article highlights the diverse ways by which type 2 immune cells regulate diseases beyond AD. The discovery of human Mas-related G protein-coupled receptor X2 on mast cells has revealed novel T cell-independent and immunoglobulin E-independent mechanisms of allergic contact dermatitis-associated and urticarial itch, respectively.

Predictors of the Effects of Flow Diversion in Very Large and Giant Aneurysms

BACKGROUND AND PURPOSE

The treatment paradigm for very large and giant aneurysms has recently changed to flow diversion, in light of the results of the Pipeline for Uncoilable or Failed Aneurysms trial. However, the effects of flow diversion were definitely unknown. We explored this topic and identified the predictors of such effects.

MATERIALS AND METHODS

We retrospectively reviewed 51 patients with unruptured aneurysms admitted to our institution for flow diversion between February 2014 and August 2019. Patients were categorized into an effect group (no filling or remnant entry) and a no-effect group (subtotal or total filling). We evaluated the aneurysm size and shape, incorporation vessel, parent artery stenosis and curvature, stagnation of contrast medium within the aneurysm, use of balloon angioplasty, and intra-aneurysm thrombus as potential predictors of the effects of flow diversion.

RESULTS

The effect group comprised 34 patients (66.7%, 34/51; no filling, 35.3%, 18/51; and remnant entry, 31.4%, 16/51). The no-effect group comprised 17 patients (33.3%, 17/51; subtotal filling, 29.4%, 15/51; and total filling, 3.9%, 2/51). An incorporation vessel and balloon angioplasty were independent risk factors for the no-effect group in multivariate logistic regression analyses (OR = 0.13 and 0.05; 95% confidence intervals, 0.02-0.62 and 0.00-0.32; P values, .021 and .004, respectively).

CONCLUSIONS

Flow diversion is effective for very large and giant aneurysms, but the outcomes require further improvement. The results of this study show that an incorporated vessel and excessive balloon angioplasty might compromise flow diversion. This finding can help improve the outcomes of flow diversion.

A Basophil-Neuronal Axis Promotes Itch Flares

Itch is an evolutionarily conserved sensation that facilitates expulsion of pathogens and noxious stimuli from the skin. However, in organ failure, cancer, and chronic inflammatory disorders like atopic dermatitis (AD), itch becomes chronic, intractable, and debilitating. Recent discoveries have implicated type 2 cell-associated cytokines such as IL-4, IL-13, and IL-31 in directly stimulating sensory neurons to promote chronic itch in AD. However, in addition to chronic itch, patients often experience intense acute itch exacerbations. Whether this form of itch represents amplification of known itch pathways or a different mechanism remains overlooked. Herein, we show that a large proportion of patients with AD harbor allergen-specific IgE and exhibit a propensity for acute itch flares. In mice, we found that while acute itch is mediated by the classical mast cell-histamine axis in steady-state, AD-associated inflammation renders this pathway dispensable. Instead, a previously unrecognized basophil-leukotriene receptor (CysLTR2) axis emerges as critical for acute itch flares. By probing fundamental itch mechanisms, our study highlights a novel basophil-neuronal circuit that may underlie a variety of pathological neuroimmune processes.

HLA Class I Polymorphisms Influencing Both Peptide Binding and KIR Interactions Are Associated with Remission among Children with Atopic Dermatitis: A Longitudinal Study

Atopic dermatitis (AD) is a disease of immune dysregulation and skin barrier dysfunction with a relapsing, remitting course and has been associated with several different genetic risk variants. HLA represent a highly variable set of genes that code for cell surface protein molecules involved in the Ag-specific immune response, including the regulation or functioning of T cells, NK cells, and APCs. The purpose of this study was to evaluate associations between HLA class I polymorphisms and the progression of AD over time. We evaluated the associations of AD symptoms and HLA class I polymorphisms based on high-resolution two-field typing in a longitudinal cohort of children with AD (up to 10 y of follow-up). Seven hundred and ninety-two children were evaluated every 6 mo, resulting in 12,752 AD evaluations. Using generalized estimating equations and corrected p values, B*44:02 was found to be associated with AD remission (1.83 [1.35, 2.47]; p = 0.0015). The HLA-B residues at position 116 (d-aspartate) and 80 (T-threonine) were associated with remission (1.42 [1.13, 1.76], p = 0.003; corrected p = 0.028) and (1.45 [1.17, 1.80], p = 0.0008; corrected p = 0.0024), respectively. B80T is a killer-cell Ig-like receptor (KIR) site. Our findings reveal that two axes of immune response (T cell and NK cell) may influence disease progression. Identifying binding pocket changes in addition to other factors (e.g., allergens) that increase the risk or severity of AD can improve our understanding of the immunologic mechanisms associated with AD and may lead to personalized therapies for improving patient care.

Beyond somatosensation: Mrgprs in mucosal tissues

Mas-related G coupled receptors (Mrgprs) are a superfamily of receptors expressed in sensory neurons that are known to transmit somatic sensations from the skin to the central nervous system. Interestingly, Mrgprs have recently been implicated in sensory and motor functions of mucosal-associated neuronal circuits. The gastrointestinal and pulmonary tracts are constantly exposed to noxious stimuli. Therefore, it is likely that neuronal Mrgpr signaling pathways in mucosal tissues, akin to their family members expressed in the skin, might relay messages that alert the host when mucosal tissues are affected by damaging signals. Further, Mrgprs have been proposed to mediate the cross-talk between sensory neurons and immune cells that promotes host-protective functions at barrier sites. Although the mechanisms by which Mrgprs are activated in mucosal tissues are not completely understood, these exciting studies implicate Mrgprs as potential therapeutic targets for conditions affecting the intestinal and airway mucosa. This review will highlight the central role of Mrgpr signaling pathways in the regulation of homeostasis at mucosal tissues.