RAG suppresses group 2 innate lymphoid cells.

Antigen specificity is the central trait distinguishing adaptive from innate immune function. Assembly of antigen-specific T cell and B cell receptors occurs through V(D)J recombination mediated by the Recombinase Activating Gene endonucleases RAG1 and RAG2 (collectively called RAG). In the absence of RAG, mature T and B cells do not develop and thus RAG is critically associated with adaptive immune function. In addition to adaptive T helper 2 (Th2) cells, group 2 innate lymphoid cells (ILC2s) contribute to type 2 immune responses by producing cytokines like Interleukin-5 (IL-5) and IL-13. Although it has been reported that RAG expression modulates the function of innate natural killer (NK) cells, whether other innate immune cells such as ILC2s are affected by RAG remains unclear. We find that in RAG-deficient mice, ILC2 populations expand and produce increased IL-5 and IL-13 at steady state and contribute to increased inflammation in atopic dermatitis (AD)-like disease. Further, we show that RAG modulates ILC2 function in a cell-intrinsic manner independent of the absence or presence of adaptive T and B lymphocytes. Lastly, employing multiomic single cell analyses of RAG1 lineage-traced cells, we identify key transcriptional and epigenomic ILC2 functional programs that are suppressed by a history of RAG expression. Collectively, our data reveal a novel role for RAG in modulating innate type 2 immunity through suppression of ILC2s.

Surgical Repair Technique for Proximal Extensor Carpi Radialis Brevis Tears.

The extensor carpi radialis brevis (ECRB) is well known to be implicated in lateral epicondylitis as a result of inflammation and degeneration. However, tears of the ECRB should be considered a separate pathology and are poorly reported in the literature. Surgical techniques for this pathology also have been poorly described. In this Technical Note, we present a surgical technique with an open approach and the use of a suture anchor for repair of isolated ruptures of the ECRB. This allows for better approximation and proper maintenance of the tendon as it completes the healing process. Surgical intervention restores anatomy and allows patients to return to full function and activities.

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 nonhistaminergic itch in mice. It was also shown that elevated serum BNP is linked to increased pruritus in nondiabetic hemodialysis patients. This study examined plasma BNP levels of 77 patients and N-terminal pro-BNP levels of 33 patients with differing types of chronic itch to see whether BNP and N-terminal pro-BNP levels can correlate with itch severity. Plasma BNP and N-terminal pro-BNP levels of all patients with itch correlated with itch numerical rating scale and in particular for patients with chronic pruritus of unknown origin. On the basis of this clinical observation, this study further showed that increasing pathophysiological levels of BNP in mice by intravenous or osmotic pump induced significant scratching. In addition, pharmacological and ablation strategies determined that BNP acts centrally by activating the natriuretic peptide receptor A in the dorsal horn of the spinal cord. These data support that BNP and N-terminal pro-BNP levels are associated with chronic itch and may be used in clinical setting.

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.

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.

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.

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/CGRPß was dependent on JAK1 in the vagus nerve, and CGRPß 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.

Hyperbolic exciton polaritons in a van der Waals magnet.

Exciton polaritons are quasiparticles of photons coupled strongly to bound electron-hole pairs, manifesting as an anti-crossing light dispersion near an exciton resonance. Highly anisotropic semiconductors with opposite-signed permittivities along different crystal axes are predicted to host exotic modes inside the anti-crossing called hyperbolic exciton polaritons (HEPs), which confine light subdiffractionally with enhanced density of states. Here, we show observational evidence of steady-state HEPs in the van der Waals magnet chromium sulfide bromide (CrSBr) using a cryogenic near-infrared near-field microscope. At low temperatures, in the magnetically-ordered state, anisotropic exciton resonances sharpen, driving the permittivity negative along one crystal axis and enabling HEP propagation. We characterize HEP momentum and losses in CrSBr, also demonstrating coupling to excitonic sidebands and enhancement by magnetic order: which boosts exciton spectral weight via wavefunction delocalization. Our findings open new pathways to nanoscale manipulation of excitons and light, including routes to magnetic, nonlocal, and quantum polaritonics.

Clinical Management of Neuropathic Itch.

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

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.

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.

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.

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.

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.

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.

Observation of Highly Anisotropic Thermal Expansion of Polymer Films.

While dimensional change under thermal loading dictates various device failure mechanisms in soft materials, the interplay between microstructures and thermal expansion remains underexplored. Here, we develop a novel method to directly probe the thermal expansion for nanoscale polymer films using an atomic force microscope as well as confining active thermal volume. In a model system, spin-coated poly(methyl methacrylate), we find that the in-plane thermal expansion is enhanced by 20-fold compared to that along the out-of-plane directions in confined dimensions. Our molecular dynamics simulations show that the collective motion of side groups along backbone chains uniquely drives the enhancement of thermal expansion anisotropy of polymers in the nanoscale limit. This work unveils the intimate role of the microstructure of polymer films on its thermal-mechanical interaction, paving a route to judiciously enhance the reliability in a broad range of thin-film devices.