Staphylococcus aureus: The Bug Behind the Itch in Atopic Dermatitis

Pruritus or itch is a defining symptom of atopic dermatitis (AD). The origins of itch are complex, and it is considered both a defense mechanism and a cause of disease that leads to inflammation and psychological stress. Considerable progress has been made in understanding the processes that trigger itch, particularly the pruritoceptive origins that are generated in the skin. This perspective review discusses the implications of a recent observation that the V8 protease expressed by Staphylococcus aureus can directly trigger sensory neurons in the skin through activation of protease-activated receptor 1. This may be a key to understanding why itch is so common in AD because S. aureus commonly overgrows in this disease owing to deficient antimicrobial defense from both the epidermis and the cutaneous microbiome. Increased understanding of the role of microbes in AD provides increased opportunities for safely improving the treatment of this disorder.

Atopic Dermatitis Itch: Scratching for an Explanation

Chronic pruritus is a cardinal symptom of atopic dermatitis (AD). The mechanisms underlying atopic itch involve intricate crosstalk among skin, immune components, and neural components. In this review, we explore these mechanisms, focusing on key players and interactions that induce and exacerbate itch. We discuss the similarities and differences between pruritus and pain in patients with AD as well as the relationship between pruritus and factors such as sweat and the skin microbiome. Furthermore, we explore novel targets that could provide significant itch relief in these patients as well as exciting future research directions to better understand atopic pruritus in darker skin types.

Two Phase 3 Trials of Lebrikizumab for Moderate-to-Severe Atopic Dermatitis

BACKGROUND

Lebrikizumab, a high-affinity IgG4 monoclonal antibody targeting interleukin-13, prevents the formation of the interleukin-4Rα-interleukin-13Rα1 heterodimer receptor signaling complex.

METHODS

We conducted two identically designed, 52-week, randomized, double-blind, placebo-controlled, phase 3 trials; both trials included a 16-week induction period and a 36-week maintenance period. Eligible patients with moderate-to-severe atopic dermatitis (adults [≥18 years of age] and adolescents [12 to <18 years of age, weighing ≥40 kg]) were randomly assigned in a 2:1 ratio to receive either lebrikizumab at a dose of 250 mg (loading dose of 500 mg at baseline and week 2) or placebo, administered subcutaneously every 2 weeks. Outcomes for the induction period were assessed up to 16 weeks and are included in this report. The primary outcome was an Investigator's Global Assessment (IGA) score of 0 or 1 (indicating clear or almost clear skin; range, 0 to 4 [severe disease]) with a reduction (indicating improvement) of at least 2 points from baseline at week 16. Secondary outcomes included a 75% improvement in the Eczema Area and Severity Index score (EASI-75 response) and assessments of itch and of itch interference with sleep. Safety was also assessed.

RESULTS

In trial 1, the primary outcome was met in 43.1% of 283 patients in the lebrikizumab group and in 12.7% of 141 patients in the placebo group (P<0.001); an EASI-75 response occurred in 58.8% and 16.2%, respectively (P<0.001). In trial 2, the primary outcome was met in 33.2% of 281 patients in the lebrikizumab group and in 10.8% of 146 patients in the placebo group (P<0.001); an EASI-75 response occurred in 52.1% and 18.1%, respectively (P<0.001). Measures of itch and itch interference with sleep indicated improvement with lebrikizumab therapy. The incidence of conjunctivitis was higher among patients who received lebrikizumab than among those who received placebo. Most adverse events during the induction period were mild or moderate in severity and did not lead to trial discontinuation.

CONCLUSIONS

In the induction period of two phase 3 trials, 16 weeks of treatment with lebrikizumab was effective in adolescents and adults with moderate-to-severe atopic dermatitis. (Funded by Dermira; ADvocate1 and ADvocate2 ClinicalTrials.gov numbers, NCT04146363 and NCT04178967, respectively.).

Cutaneous Neuroimmune Interactions of TSLP and TRPV4 Play Pivotal Roles in Dry Skin-Induced Pruritus

Dry skin is a symptom of skin barrier dysfunction that evokes pruritus; however, the cutaneous neuroimmune interactions underlying dry skin-induced pruritus remain unclear. Therefore, we aimed to elucidate the mechanisms underlying dry skin-induced pruritus. To this end, an acetone/ethanol/water (AEW)-induced mouse model of dry skin was used in this study. We observed that the production of thymic stromal lymphopoietin (TSLP) significantly increased in the keratinocytes of AEW mice. Importantly, treatment with an antagonist of transient receptor potential cation channel subfamily V member 4 (TRPV4), HC067047, ameliorated dry skin conditions in AEW mice. The symptoms of dry skin were significantly reduced in Trpv4 knockout (KO) mice following treatment with AEW. The increase in the intracellular calcium levels by TSLP in the dorsal root ganglia (DRG) of Trpv4 KO mice was also significantly attenuated. The spontaneous scratching bouts were significantly decreased in both the HC067047-treated and Trpv4 KO AEW mice. Importantly, the TSLP-dependent release of tryptase from the mast cells was significantly reduced in both the HC067047-treated mice and Trpv4 KO AEW mice. Notably, inhibition of the TSLP-induced signaling pathway in DRG selectively reduced the spontaneous scratching bouts in AEW mice. Overall, the results demonstrated that the cutaneous neuroimmune interactions of TSLP and TRPV4 play pivotal roles in dry skin-induced pruritus.

Connections between Immune-Derived Mediators and Sensory Nerves for Itch Sensation

Although histamine is a well-known itch mediator, histamine H1-receptor blockers often lack efficacy in chronic itch. Recent molecular and cellular based studies have shown that non-histaminergic mediators, such as proteases, neuropeptides and cytokines, along with their cognate receptors, are involved in evocation and modulation of itch sensation. Many of these molecules are produced and secreted by immune cells, which act on sensory nerve fibers distributed in the skin to cause itching and sensitization. This understanding of the connections between immune cell-derived mediators and sensory nerve fibers has led to the development of new treatments for itch. This review summarizes current knowledge of immune cell-derived itch mediators and neuronal response mechanisms, and discusses therapeutic agents that target these systems.

Clinical Relevance of Skin Pain in Atopic Dermatitis

Skin pain is increasingly recognized as an impactful symptom in atopic dermatitis (AD) because of its association with patient discomfort, disease burden, and reduced quality of life. Although the nature of skin pain in AD has not been systematically studied and is therefore not well understood, patients report soreness, discomfort, and tenderness that may reflect peripheral and central pain sensitization. The high prevalence of skin pain suggests that it is not adequately addressed by current therapies for AD and may be undertreated compared with other symptoms. This review discusses the clinical relevance of skin pain with respect to its experience, pathophysiology, relationship with itch, and treatment implications. Recent studies suggest that skin pain presents as a neuropathic symptom independent from itch and the &ldquo;itch-scratch cycle&rdquo;, and poses a unique burden to patients. Recognition of the significant consequences of skin pain and discomfort should reinforce the need to assess and treat this symptom in patients with moderate-to-severe AD. J Drugs Dermatol. 2020;19(10)921-926. doi:10.36849/JDD.2020.5498.

Astrocytic STAT3 activation and chronic itch require IP3R1/TRPC-dependent Ca2+ signals in mice

BACKGROUND

Chronic itch is a debilitating symptom of inflammatory skin diseases, but the underlying mechanism is poorly understood. We have recently demonstrated that astrocytes in the spinal dorsal horn become reactive in models of atopic and contact dermatitis via activation of the transcription factor signal transducer and activator of transcription 3 (STAT3) and critically contribute to chronic itch. In general, STAT3 is transiently activated; however, STAT3 activation in reactive astrocytes of chronic itch model mice persistently occurs via an unknown mechanism.

OBJECTIVE

We aimed to determine the mechanisms of persistent activation of astrocytic STAT3 in chronic itch conditions.

METHODS

To determine the factors that are required for persistent activation of astrocytic STAT3, Western blotting and calcium imaging with cultured astrocytes or spinal cord slices were performed. Thereafter, chronic itch model mice were used for genetic and behavioral experiments to confirm the role of the factors determined to mediate persistent STAT3 activation from in vitro and ex vivo experiments in chronic itch.

RESULTS

IP3 receptor type 1 (IP3R1) knockdown in astrocytes suppressed IL-6-induced persistent STAT3 activation and expression of lipocalin-2 (LCN2), an astrocytic STAT3-dependent inflammatory factor that is required for chronic itch. IP3R1-dependent astrocytic Ca2+ responses involved Ca2+ influx through the cation channel transient receptor potential canonical (TRPC), which was required for persistent STAT3 activation evoked by IL-6. IL-6 expression was upregulated in dorsal root ganglion neurons in a mouse model of chronic itch. Dorsal root ganglion neuron-specific IL-6 knockdown, spinal astrocyte-specific IP3R1 knockdown, and pharmacologic spinal TRPC inhibition attenuated LCN2 expression and chronic itch.

CONCLUSION

Our findings suggest that IP3R1/TRPC channel-mediated Ca2+ signals elicited by IL-6 in astrocytes are necessary for persistent STAT3 activation, LCN2 expression, and chronic itch, and they may also provide new targets for therapeutic intervention.

Autoreactive Peripheral Blood T Helper Cell Responses in Bullous Pemphigoid and Elderly Patients With Pruritic Disorders

Bullous pemphigoid (BP) is a prototypic autoimmune disorder of the elderly, characterized by serum IgG autoantibodies, namely anti-BP180 and anti-BP230, directed against components of the basal membrane zone that lead to sub-epidermal loss of adhesion. Pruritus may be indicative of a pre-clinical stage of BP, since a subset of these patients shows serum IgG autoantibodies against BP230 and/or BP180 while chronic pruritus is increasingly common in the elderly population and is associated with a variety of dermatoses. Clinical and experimental evidence further suggests that pruritus of the elderly may be linked to autoimmunity with loss of self-tolerance against cutaneous autoantigens. Thus, the objective of this study was to determine autoreactive T cell responses against BP180 in elderly patients in comparison to patients with BP. A total of 22 elderly patients with pruritic disorders, 34 patients with bullous or non-bullous BP and 34 age-matched healthy controls were included in this study. The level of anti-BP180 and anti-BP230 IgG serum autoantibodies, Bullous Pemphigoid Disease Area Index (BPDAI), and pruritus severity were assessed for all patients and controls. For characterization of the autoreactive T cell response, peripheral blood mononuclear cells were stimulated ex vivo with recombinant BP180 proteins (NH2- and COOH-terminal domains) and the frequencies of BP180-specific T cells producing interferon-γ, interleukin (IL)-5 or IL-17 were subsequently determined by ELISpot assay. Patients with BP showed a mixed Th1/Th2 response against BP180 while autoreactive Th1 cells were identified in a minor subset of elderly patients with pruritic disorders. Furthermore, our T cell characterization revealed that therapeutic application of topical clobetasol propionate ointment in BP patients significantly reduced peripheral blood BP180-specific T cells, along with clinically improved symptoms, strongly suggesting a systemic immunosuppressive effect of this treatment.

Analysis of the long-term efficacy and safety of subcutaneous immunotherapy for atopic dermatitis

Introduction: Atopic dermatitis (AD) is a chronic and relapsing inflammatory skin disease characterized by severe pruritus and eczematous skin lesions. Subcutaneous immunotherapy (SCIT) refers to repeated contact with gradually increasing doses of allergen extracts, which improve patient tolerance to such allergens and controls, or reduces allergic symptoms. This study aimed to explore the long-term efficacy and safety of SCIT for patients with AD sensitized to house-dust mite (HDM). Methods: We conducted a retrospective analysis of 378 patients with HDM-sensitized AD. Among these patients, 164 received SCIT plus pharmacotherapy for 3 years (SCIT group) and the other 214 patients received only pharmacotherapy (non-SCIT group). The scoring atopic dermatitis (SCORAD) and pruritus visual analog scale (VAS) scores, laboratory test results, and adverse effects were recorded. Results: The SCORAD and pruritus VAS scores significantly decreased in the SCIT group. Also, the SCIT group showed higher reduction ratios of SCORAD and pruritus VAS scores than those observed in the non-SCIT group at 3 years after treatment initiation. The risk of development of new sensitization was higher in the non-SCIT group than in the SCIT group (relative risk 1.92 [95% confidence interval {CI}, 1.30-2.85]; p < 0.05). The eosinophil count of the participants significantly differed in the complete response (CR) group (p < 0.05) but not in the non-CR group (p = 0.098). However, the serum total immunoglobulin E value was not significantly reduced (p = 0.204). Of 8421 injections given to the patients, 231 injections (2.74%) showed adverse effects during the treatment period. Conclusion: Three years of SCIT can significantly reduce the severity and pruritus of moderate-to-severe AD with HDM sensitization. Patients who are multisensitized can also benefit from HDM SCIT. Patients can achieve long-term effects, such as prevention of neoallergen sensitization and inhibition of the allergy march.

A basophil-neuronal axis promotes itch

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 such as atopic dermatitis (AD), itch becomes chronic, intractable, and debilitating. In addition to chronic itch, patients often experience intense acute itch exacerbations. Recent discoveries have unearthed the neuroimmune circuitry of itch, leading to the development of anti-itch treatments. However, mechanisms underlying acute itch exacerbations remain overlooked. Herein, we identify that a large proportion of patients with AD harbor allergen-specific immunoglobulin E (IgE) and exhibit a propensity for acute itch flares. In mice, while allergen-provoked acute itch is mediated by the mast cell-histamine axis in steady state, AD-associated inflammation renders this pathway dispensable. Instead, a previously unrecognized basophil-leukotriene (LT) axis emerges as critical for acute itch flares. By probing fundamental itch mechanisms, our study highlights a basophil-neuronal circuit that may underlie a variety of neuroimmune processes.

Resolvin D3 controls mouse and human TRPV1-positive neurons and preclinical progression of psoriasis

Rationale: Psoriasis is a chronic inflammatory disease caused by a complex interplay between the immune and nervous systems with recurrent scaly skin plaques, thickened stratum corneum, infiltration and activation of inflammatory cells, and itch. Despite an increasing availability of immune therapies, they often have adverse effects, high costs, and dissociated effects on inflammation and itch. Activation of sensory neurons innervating the skin and TRPV1 (transient receptor potential vanilloid 1) are emerging as critical components in the pathogenesis of psoriasis, but little is known about their endogenous inhibitors. Recent studies have demonstrated that resolvins, endogenous lipid mediators derived from omega-3 fatty acids, are potent inhibitors of TRP channels and may offer new therapies for psoriasis without known adverse effects. Methods: We used behavioral, electrophysiological and biochemical approaches to investigate the therapeutic effects of resolvin D3 (RvD3), a novel family member of resolvins, in a preclinical model of psoriasis consisting of repeated topical applications of imiquimod (IMQ) to murine skin, which provokes inflammatory lesions that resemble human psoriasis. Results: We report that RvD3 specifically reduced TRPV1-dependent acute pain and itch in mice. Mechanistically, RvD3 inhibited capsaicin-induced TRPV1 currents in dissociated dorsal root ganglion (DRG) neurons via the N-formyl peptide receptor 2 (i.e. ALX/FPR2), a G-protein coupled receptor. Single systemic administration of RvD3 (2.8 mg/kg) reversed itch after IMQ, and repeated administration largely prevented the development of both psoriasiform itch and skin inflammation with concomitant decreased in calcitonin gene-related peptide (CGRP) expression in DRG neurons. Accordingly, specific knockdown of CGRP in DRG was sufficient to prevent both psoriasiform itch and skin inflammation similar to the effects following RvD3 administration. Finally, we elevated the translational potential of this study by showing that RvD3 significantly inhibited capsaicin-induced TRPV1 activity and CGRP release in human DRG neurons. Conclusions: Our findings demonstrate a novel role for RvD3 in regulating TRPV1/CGRP in mouse and human DRG neurons and identify RvD3 and its neuronal pathways as novel therapeutic targets to treat psoriasis.

Amelioration of Compound 48/80-Mediated Itch and LL-37-Induced Inflammation by a Single-Stranded Oligonucleotide

Numerous inflammatory skin disorders display a high prevalence of itch. The Mas-related G protein coupled receptor X2 (MRGPRX2) has been shown to modulate itch by inducing non-IgE-mediated mast cell degranulation and the release of endogenous inducers of pruritus. Various substances collectively known as basic secretagogues, which include inflammatory peptides and certain drugs, can trigger MRGPRX2 and thereby induce pseudo-allergic reactions characterized by histamine and protease release as well as inflammation. Here, we investigated the capacity of an immunomodulatory single-stranded oligonucleotide (ssON) to modulate IgE-independent mast cell degranulation and, more specifically, its ability to inhibit the basic secretagogues compound 48/80 (C48/80)-and LL-37 in vitro and in vivo. We examined the effect of ssON on MRGPRX2 activation in vitro by measuring degranulation in a human mast cell line (LAD2) and calcium influx in MRGPRX2-transfected HEK293 cells. To determine the effect of ssON on itch, we performed behavioral studies in established mouse models and collected skin biopsies for histological analysis. Additionally, with the use of a rosacea mouse model and RT-qPCR, we investigated the effect on ssON on LL-37-induced inflammation. We reveal that both mast cell degranulation and calcium influx in MRGPRX2 transfected HEK293 cells, induced by the antimicrobial peptide LL-37 and the basic secretagogue C48/80, are effectively inhibited by ssON in a dose-dependent manner. Further, ssON demonstrates a capability to inhibit LL-37 and C48/80 activation in vivo in two mouse models. We show that intradermal injection of ssON in mice is able to block itch induced via C48/80 in a dose-dependent manner. Histological staining revealed that ssON inhibits acute mast cell degranulation in murine skin treated with C48/80. Lastly, we show that ssON treatment ameliorates LL-37-induced inflammation in a rosacea mouse model. Since there is a need for new therapeutics targeting non-IgE-mediated activation of mast cells, ssON could be used as a prospective drug candidate to resolve itch and inflammation in certain dermatoses.

Efficacy and Safety of Calcipotriene 0.005%/Betamethasone Dipropionate 0.064% Foam With Apremilast for Moderate Plaque Psoriasis

OBJECTIVE

To demonstrate the efficacy and safety of adding fixed-dose combination calcipotriene 0.005% plus betamethasone dipropionate 0.064% (Cal/BD) foam to oral apremilast in treating moderate plaque psoriasis.

METHODS

A 16-week, investigator-blinded study in patients with moderate psoriasis (Physician&rsquo;s Global Assessment [PGA] score of 3). Patients were randomized 1:1 to Cal/BD foam plus apremilast or vehicle foam plus apremilast for 4 weeks, followed by 8 weeks of apremilast monotherapy, and then 4 weeks of combination therapy as in the original randomization schedule. Efficacy assessments &ndash; Psoriasis Area and Severity Index (PASI), PGA, body surface area (BSA), visual analog scale (VAS) for pruritus, and quality of life (QoL) &ndash; and safety were evaluated at weeks 1, 2, 3, 4, 12, and 16.

RESULTS

28 subjects were enrolled (mean age, 64 years; 67.9% males). Cal/BD foam plus apremilast group achieved statistically significantly greater improvement than vehicle foam plus apremilast in PASI75 (50% vs 7%; P=.003), PGA score of &ldquo;clear&rdquo; or &ldquo;almost clear&rdquo; (43% vs 7%; P=.001), and VAS score (2 vs 5; P=.0079) at week 4. BSA and QoL improvements were also observed. Most efficacy assessments worsened after withdrawing Cal/BD foam for 8 weeks but recovered after reinitiating Cal/BD foam from week 12 to week 16. Cal/BD foam plus apremilast appeared to be safe and well tolerated.

CONCLUSIONS

In the treatment of moderate plaque psoriasis, Cal/BD foam plus apremilast provided more benefits than with apremilast alone. These improvements appeared to be lost when Cal/BD foam was withdrawn but recovered when Cal/BD foam was reinitiated. J Drugs Dermatol. 2020;19(9):874-880. doi:10.36849/JDD.2020.5020.

Efficacy and Safety of Calcipotriene 0.005%/Betamethasone Dipropionate 0.064% Foam With Apremilast for Moderate Plaque Psoriasis

OBJECTIVE

To demonstrate the efficacy and safety of adding fixed-dose combination calcipotriene 0.005% plus betamethasone dipropionate 0.064% (Cal/BD) foam to oral apremilast in treating moderate plaque psoriasis.

METHODS

A 16-week, investigator-blinded study in patients with moderate psoriasis (Physician&rsquo;s Global Assessment [PGA] score of 3). Patients were randomized 1:1 to Cal/BD foam plus apremilast or vehicle foam plus apremilast for 4 weeks, followed by 8 weeks of apremilast monotherapy, and then 4 weeks of combination therapy as in the original randomization schedule. Efficacy assessments &ndash; Psoriasis Area and Severity Index (PASI), PGA, body surface area (BSA), visual analog scale (VAS) for pruritus, and quality of life (QoL) &ndash; and safety were evaluated at weeks 1, 2, 3, 4, 12, and 16.

RESULTS

28 subjects were enrolled (mean age, 64 years; 67.9% males). Cal/BD foam plus apremilast group achieved statistically significantly greater improvement than vehicle foam plus apremilast in PASI75 (50% vs 7%; P=.003), PGA score of &ldquo;clear&rdquo; or &ldquo;almost clear&rdquo; (43% vs 7%; P=.001), and VAS score (2 vs 5; P=.0079) at week 4. BSA and QoL improvements were also observed. Most efficacy assessments worsened after withdrawing Cal/BD foam for 8 weeks but recovered after reinitiating Cal/BD foam from week 12 to week 16. Cal/BD foam plus apremilast appeared to be safe and well tolerated.

CONCLUSIONS

In the treatment of moderate plaque psoriasis, Cal/BD foam plus apremilast provided more benefits than with apremilast alone. These improvements appeared to be lost when Cal/BD foam was withdrawn but recovered when Cal/BD foam was reinitiated. J Drugs Dermatol. 2020;19(9):874-880. doi:10.36849/JDD.2020.5020.

Diagnosis and treatment of primary biliary cholangitis

Primary biliary cholangitis is a cholestatic, chronic autoimmune liver disease with a wide individual variation in disease progression. The diagnosis is predominantly based on chronic elevation of alkaline phosphatase and the presence of anti-mitochondrial antibodies or other specific antinuclear antibodies (i.e. anti-gp210 and anti-sp100). Even in early-stage disease, health-related quality of life can be severely impaired by symptoms such as pruritus, fatigue, and sicca syndrome and metabolic bone disease should be assessed and treated. The prognosis of the disease is, however, largely determined by the development of cirrhosis and its complications. Ursodeoxycholic acid is associated with an improved prognosis and should be initiated and continued in all patients. Clinical outcome is related to the biochemical response to ursodeoxycholic acid, but the prognosis of those with an incomplete response is still better than those who remain untreated. Obeticholic acid was recently approved as second-line treatment and bezafibrate may serve as an adequate off-label alternative, particularly in patients with pruritus. Preliminary data suggest an additive effect of triple therapy with ursodeoxycholic acid, obeticholic acid, and bezafibrate, whereas other promising drugs are being evaluated in clinical trials.

Systemic Immunomodulatory Treatments for Patients With Atopic Dermatitis: A Systematic Review and Network Meta-analysis

Importance

Most clinical trials assessing systemic immunomodulatory treatments for patients with atopic dermatitis are placebo-controlled.

Objective

To compare the effectiveness and safety of systemic immunomodulatory treatments for patients with atopic dermatitis in a systematic review and network meta-analysis.

Data Sources

The Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Latin American and Caribbean Health Science Information database, Global Resource of Eczema Trials database, and clinical trial registries were searched from inception to October 28, 2019.

Study Selection

English-language randomized clinical trials of 8 weeks or more of treatment with systemic immunomodulatory medications for moderate to severe atopic dermatitis were included. Titles, abstracts, and articles were screened in duplicate. Of 10 324 citations, 39 trials were included.

Data Extraction and Synthesis

Data were extracted in duplicate, and the review adhered to Preferred Reporting Items for Systematic Reviews and Meta-analyses for Network Meta-Analyses guidelines. Random-effects bayesian network meta-analyses were performed and certainty of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation criteria.

Main Outcomes and Measures

Prespecified outcomes were change in signs of disease, symptoms, quality of life, itch, withdrawals, and serious adverse events.

Results

A total of 39 trials with 6360 patients examining 20 medications and placebo were included. Most trials were conducted for adults receiving up to 16 weeks of therapy. Dupilumab, 300 mg every 2 weeks, was associated with improvement in the Eczema Area and Severity Index score vs placebo (mean difference, 11.3-point reduction; 95% credible interval [CrI], 9.7-13.1 [high certainty]). Cyclosporine (standardized mean difference, -1.1; 95% CrI, -1.7 to -0.5 [low certainty]) and dupilumab (standardized mean difference, -0.9; 95% CrI, -1.0 to -0.8 [high certainty]) were similarly effective vs placebo in clearing clinical signs of atopic dermatitis and may be superior to methotrexate (standardized mean difference, -0.6; 95% CrI, -1.1 to 0.0 [low certainty]) and azathioprine (standardized mean difference, -0.4; 95% CrI, -0.8 to -0.1 [low certainty]). Several investigational medications for atopic dermatitis are promising, but data to date are limited to small early-phase trials. Safety analyses were limited by low event rates.

Conclusions and Relevance

Dupilumab and cyclosporine may be more effective for up to 16 weeks of treatment than methotrexate and azathioprine for treating adult patients with atopic dermatitis. More studies directly comparing established and novel treatments beyond 16 weeks are needed and will be incorporated into future updates of this review.

Ipilimumab plus nivolumab for patients with metastatic uveal melanoma: a multicenter, retrospective study

BACKGROUND

Uveal melanoma (UM) is the most common intraocular malignancy in adults. In contrast to cutaneous melanoma (CM), there is no standard therapy, and the efficacy and safety of dual checkpoint blockade with nivolumab and ipilimumab is not well defined.

METHODS

We conducted a retrospective analysis of patients with metastatic UM (mUM) who received treatment with ipilimumab plus nivolumab across 14 academic medical centers. Toxicity was graded using National Cancer Institute Common Terminology Criteria for Adverse Events V.5.0. Progression-free survival (PFS) and overall survival (OS) were calculated using Kaplan-Meier methodology.

RESULTS

89 eligible patients were identified. 45% had received prior therapy, which included liver directed therapy (29%), immunotherapy (21%), targeted therapy (10%) and radiation (16%). Patients received a median 3 cycles of ipilimumab plus nivolumab. The median follow-up time was 9.2 months. Overall response rate was 11.6%. One patient achieved complete response (1%), 9 patients had partial response (10%), 21 patients had stable disease (24%) and 55 patients had progressive disease (62%). Median OS from treatment initiation was 15 months and median PFS was 2.7 months. Overall, 82 (92%) of patients discontinued treatment, 34 due to toxicity and 27 due to progressive disease. Common immune-related adverse events were colitis/diarrhea (32%), fatigue (23%), rash (21%) and transaminitis (21%).

CONCLUSIONS

Dual checkpoint inhibition yielded higher response rates than previous reports of single-agent immunotherapy in patients with mUM, but the efficacy is lower than in metastatic CM. The median OS of 15 months suggests that the rate of clinical benefit may be larger than the modest response rate.

Investigating the epithelial barrier and immune signatures in the pathogenesis of equine insect bite hypersensitivity

Insect bite hypersensitivity (IBH) is a Th-2, IgE-mediated dermatitis of horses caused by bites of insects of the genus Culicoides that has common features with human atopic dermatitis. Together with Th-2 cells, the epithelial barrier plays an important role in development of type I hypersensitivities. In order to elucidate the role of the epithelial barrier and of the skin immune response in IBH we studied the transcriptome of lesional whole skin of IBH-horses (IBH-LE; n = 9) in comparison to non-lesional skin (IBH-NL; n = 8) as well as to skin of healthy control horses (H; n = 9). To study the "baseline state" of the epithelial barrier, we investigated the transcriptome of non-lesional epidermis in IBH-horses (EPI-IBH-NL; n = 10) in comparison with healthy epidermis from controls (EPI-H; n = 9). IBH-LE skin displayed substantial transcriptomic difference compared to H. IBH-LE was characterized by a downregulation of genes involved in tight junction formation, alterations in keratins and substantial immune signature of both Th-1 and Th-2 types with particular upregulation of IL13, as well as involvement of the hypoxic pathway. IBH-NL shared a number of differentially expressed genes (DEGs) with IBH-LE, but was overall more similar to H skin. In the epidermis, genes involved in metabolism of epidermal lipids, pruritus development, as well as IL25, were significantly differentially expressed between EPI-IBH-NL and EPI-H. Taken together, our data suggests an impairment of the epithelial barrier in IBH-affected horses that may act as a predisposing factor for IBH development. Moreover, these new mechanisms could potentially be used as future therapeutic targets. Importantly, many transcriptional features of equine IBH skin are shared with human atopic dermatitis, confirming equine IBH as a natural model of skin allergy.

Fermented Morinda citrifolia (Noni) Alleviates DNCB-Induced Atopic Dermatitis in NC/Nga Mice through Modulating Immune Balance and Skin Barrier Function

Morinda citrifolia, a fruit generally known as "Noni", has been traditionally used in parts of East Asia to relieve inflammatory diseases. Although several studies using noni have been reported, the effect of fermented Morinda citrifolia (F.NONI) on atopic dermatitis (AD) has not been investigated. Thus, we aimed to investigate the improving effect of F.NONI treatment on AD-like skin lesions and elucidate molecular mechanisms. F.NONI was prepared by the fermentation of noni fruit with probiotics and then extracted. F.NONI was orally administrated to NC/Nga mice to evaluate its therapeutic effect on 2,4-dinitrochlorobenzene (DNCB)-induced AD. Oral administration of F.NONI significantly alleviated AD lesions and symptoms such as dermatitis scores, ear thickness, scratching behavior, epidermal thickness, and infiltration of inflammatory cells (e.g., mast cells and eosinophils). In addition, F.NONI treatment reduced the levels of histamine, IgE and IgG1/IgG2a ratio, thymus and activation regulated chemokine (TARC), and thymic stromal lymphopoietin (TSLP) in serum and beneficially modulated the expressions of Th1, Th2, Th17, and Th22-mediated cytokines in lesioned skin and splenocytes. Furthermore, the expressions of the skin barrier-related proteins including filaggrin (FLG), loricrin (LOR), involucrin (IVL), zonula occludens-1 (ZO-1), and occludin (OCC) were restored by F.NONI treatment. Taken together, these results suggest that F.NONI could be a therapeutic agent to attenuate AD-like skin lesions through modulating the immune balance and skin barrier function.

Double blinded, vehicle controlled, crossover study on the efficacy of a topical endocannabinoid membrane transporter inhibitor in atopic Beagles

The endocannabinoid system is important for skin homeostasis and alterations are linked to inflammatory diseases like atopic dermatitis (AD). Importantly, activation of cannabinoid receptor CB2 decreases pruritus and inflammation in mouse models. Reduction of inactivation of endogenous cannabinoids could, therefore, be a therapeutic option for AD. Dogs spontaneously develop AD, which closely mimics the human disease making them suitable to test new therapies. Our study aimed to test the effects of a topical endocannabinoid membrane transporter inhibitor (WOL067-531, 1% gel) on pruritus and dermatitis in a canine model of AD. Nineteen Beagles allergic to dust mites (DM) were randomized to receive either active ingredient or vehicle on inguinal area while challenged epicutaneously with DM twice weekly for 28 days. Treatment was administered twice daily and started after three challenges (day 8). Dermatitis and pruritus were scored weekly by personnel blinded to treatment allocation. Dermatitis was scored using a validated scoring system and pruritus was scored using camera recordings. After a 4-week washout, dogs were crossed over and the study was repeated. On days 15 and 22, dermatitis scores were significantly increased after DM challenge in the vehicle group (16.34, p = 0.0089 and 7.42, p = 0.04845, respectively) but not in the active ingredient group (p = 0.3177 and p = 0.3190, respectively). Significant decrease on pruritus both on inguinal area and overall (p = 0.048 and p = 0.032, respectively) occurred in the active ingredient group. No adverse effects were noted. In conclusion, the newly developed topical endocannabinoid membrane transporter inhibitor (WOL067-531) minimized allergic flares and pruritus in a canine model of AD.

Pruritus secondary to primary biliary cholangitis: a review of the pathophysiology and management with phototherapy

BACKGROUND

Primary biliary cholangitis (PBC) is an autoimmune hepatobiliary disorder characterized by destruction of liver bile ducts leading to intrahepatic cholestasis. It causes intractable pruritus for which ultraviolet (UV)B phototherapy is an experimental treatment when alternative therapies fail. The pathophysiology of cholestatic itch and the mechanism of action of narrowband UVB in this condition remains poorly understood.

OBJECTIVES

To summarize the current literature and propose testable hypotheses for the mechanism of action of phototherapy in attenuating itch.

METHODS

A focused PubMed search for articles relating to the pathogenesis of itch in cholestatic disease was performed. A total of 3855 articles were screened and 50 were found suitable for literature review. Evidence from this literature review was combined with author expertise in the area.

RESULTS

Formulated hypotheses focus on the role of bile salts, autotaxin and specific receptors including G-protein-coupled bile acid receptor, Gpbar1 (also known as TGR5) and the nuclear transcription factor farnesoid X receptor.

CONCLUSIONS

Several testable mechanisms through which phototherapy may exert its effects are discussed in this review. The next steps are to carry out an objective assessment of the efficacy of phototherapy in cholestatic pruritus, gain further knowledge on the underlying pathways, and subsequently trial its use against current licensed therapies. Such studies could lead to increased mechanistic understanding, identification of novel therapeutic targets and the potential to refine phototherapy protocols, leading to improved control of itch and quality of life in patients with PBC. What's already known about this topic? Primary biliary cholangitis (PBC) is frequently associated with intractable pruritus for which current treatment options are often unsuccessful. Phototherapy is used as an experimental treatment for PBC-associated pruritus when alternative better-studied treatments fail. What does this study add? This study reviews the current literature on the pathophysiology and management of cholestatic pruritus, an area which remains poorly understood. We propose testable hypotheses of the mechanisms behind the attenuation of cholestatic pruritus with phototherapy.

Characterizing Pruritus in Autoimmune Connective Tissue Diseases

Background: Autoimmune connective tissue diseases (ACTDs) are a broad range of diseases featured by immune dysregulation, and often have multisystem involvement with prominent skin manifestations. Pruritus is one of the most common symptoms in these diseases, with significant impact on the quality of life of patients. Objective: To characterize the frequency, location, severity, and timing relative to disease onset of pruritus in different ACTDs. Methods: A chart review of all patients seen in the Rheumatology-Dermatology clinic at Massachusetts General Hospital. Results: Itch was a troubling symptom in 83% of dermatomyositis (DM), 61% of systemic lupus erythematosus (SLE), 59% of Sjogren syndrome (SJO), 22% of systemic sclerosis (SSc), and 60% of mixed connective tissue disease. In DM and SLE, itch paralleled the course of inflammatory skin manifestations in 83% and 45%, respectively. Itch in DM is more intense and more treatment resistant in 12% vs 1% in SLE. In contrast, itch in SSc and SJO tended to occur later in the disease course, 86% vs 42%, respectively. Conclusion: Itch is common in all ACTDs and often under-evaluated and under treated. Pruritus is more common and more severe in DM than in SLE. Treatment of pruritus in ACTDs can be challenging, and sometimes multi-modal therapy is warranted. J Drugs Dermatol. 2019;18(10):995-998.

Pruritus in allergy and immunology

Although evolutionarily conserved to expel ectoparasites and aid in the clearance of toxins and noxious environmental stimuli from the host, the type 2 immune response can become pathologic in the setting of a variety of allergic disorders. Itch can be a behavioral extension of type 2 immunity by evoking scratching and, in the setting of disease, can become chronic and thus highly pathologic as well. Classically, our understanding of itch mechanisms has centered around the canonical IgE-mast cell-histamine axis. However, therapies aimed at blocking the histaminergic itch pathway have been largely ineffective, suggesting the existence of nonhistaminergic itch pathways. Indeed, recent advances in itch biology have provided critical new insight into a variety of novel therapeutic avenues for chronic itch in the setting of a number of allergic disorders. Here we highlight how these new developments will likely inform the problem of pruritus in a variety of well-established and emerging conditions in the field of allergy.

Eosinophils are a Major Source of Interleukin-31 in Bullous Pemphigoid

Bullous pemphigoid (BP) is characterized by substantial skin and blood eosinophilia as well as intensive pruritus. Since the pruritogenic cytokine interleukin (IL)-31 is increased in inflammatory skin diseases the aim of this study was to determine whether IL-31 plays a role in BP. Using immunofluorescence, IL-31 expression was analysed in eosinophils derived from blister fluids and skin from patients with BP and IL-31 levels in blister fluids, serum and culture supernatants were determined by enzyme-linked immunoassay (ELISA). High levels of IL-31 expression were observed in BP blister fluids, but they were only marginally elevated in BP serum compared with healthy controls. Eosinophils from either BP blister fluids or skin biopsies showed strong expression of IL-31. Furthermore, peripheral blood eosinophils from patients with BP, but not healthy controls, released high levels of IL-31, reflecting those in blister fluids. In conclusion, eosinophils are a major source of IL-31 in BP and this cytokine may contribute to itch in patients with BP.

Clinical Characteristics of Pruritus in Systemic Sclerosis Vary According to the Autoimmune Subtype

Pruritus is a frequent symptom in systemic sclerosis (SSc), with a prevalence of 40-65%, but its pathophysiology is poorly understood. This study investigated the immunological component of pruritus. Fifty-six patients with SSc responded to a standardized questionnaire regarding both SSc disease and pruritus characteristics. Among patients with SSc, those with pruritus did not display a particular immunological profile (inflammatory, humoral, and/or cellular factors), but pruritus was, in most cases, concomitant with the development of SSc. Thus, pruritus characteristics were evaluated further, according to the detection of anti-centromere autoantibodies (ACA), into ACA+ (n = 17) and ACA- (n = 19). The ACA+ subgroup was characterized by a longer evolution of SSc and pruritus, pruritus present outside the sclerotic area, and a shorter daily duration of pruritus. In conclusion, the concomitant appearance of the 2 processes and the differences observed between ACA+ and ACA- subgroups support the presence of an immunological component in pruritus.

BP180 dysfunction triggers spontaneous skin inflammation in mice

BP180, also known as collagen XVII, is a hemidesmosomal component and plays a key role in maintaining skin dermal/epidermal adhesion. Dysfunction of BP180, either through genetic mutations in junctional epidermolysis bullosa (JEB) or autoantibody insult in bullous pemphigoid (BP), leads to subepidermal blistering accompanied by skin inflammation. However, whether BP180 is involved in skin inflammation remains unknown. To address this question, we generated a BP180-dysfunctional mouse strain and found that mice lacking functional BP180 (termed ΔNC16A) developed spontaneous skin inflammatory disease, characterized by severe itch, defective skin barrier, infiltrating immune cells, elevated serum IgE levels, and increased expression of thymic stromal lymphopoietin (TSLP). Severe itch is independent of adaptive immunity and histamine, but dependent on increased expression of TSLP by keratinocytes. In addition, a high TSLP expression is detected in BP patients. Our data provide direct evidence showing that BP180 regulates skin inflammation independently of adaptive immunity, and BP180 dysfunction leads to a TSLP-mediated itch. The newly developed mouse strain could be a model for elucidation of disease mechanisms and development of novel therapeutic strategies for skin inflammation and BP180-related skin conditions.

Early Relief of Pruritus in Atopic Dermatitis with Crisaborole Ointment, A Non-steroidal, Phosphodiesterase 4 Inhibitor

Pruritus occurs in all patients with atopic dermatitis and requires quick relief to reduce disease exacerbation and improve quality of life. Crisaborole ointment is a non-steroidal phosphodiesterase 4 inhibitor for the treatment of mild-to-moderate atopic dermatitis. This post hoc analysis explores crisaborole ointment for early relief of pruritus in patients with mild to moderate atopic dermatitis from 2 phase III studies. Patients received crisaborole or vehicle twice daily for 28 days. Pruritus was graded on a 4-point scale of none (0) to severe (3). Early improvement in pruritus required a score of none (0) or mild (1), with a ≥ 1-grade improvement from baseline on day 6. Significantly more patients experienced early improvement in pruritus with crisaborole than with vehicle (56.6% vs 39.5%; p< 0.001), including at earliest assessment (day 2, 34.3% vs 27.3%; p = 0.013). Crisaborole is a topical treatment option that can rapidly relieve atopic dermatitis-associated pruritus.

Sensitive skin is highly frequent in extrinsic atopic dermatitis and correlates with disease severity markers but not necessarily with skin barrier impairment

BACKGROUND

Sensitive skin is a condition of cutaneous hypersensitivity to environmental factors. Lactic acid stinging test (LAST) is commonly used to assess sensitive skin and composed of four distinct sensations (pain, burning sensation, itch, and crawly feeling). A link between sensitive skin and barrier dysfunction has been proposed in atopic dermatitis (AD) patients. However, clinical and laboratory factors that are associated with sensitive skin remain unelucidated.

OBJECTIVE

To investigate relationship between sensitive skin and AD-associated markers.

METHODS

Forty-two Japanese AD patients and 10 healthy subjects (HS) were enrolled. AD patients were divided into extrinsic (EAD; high IgE levels) and intrinsic (IAD; normal IgE levels) types. We conducted 1% LAST by assessing the four distinct sensations and calculated the frequencies of sensitive skin in EAD, IAD, and HS. We also performed clinical AD-related tests, including transepidermal water loss (TEWL), visual analogue scale (VAS) of pruritus, and quality of life, and measured laboratory markers, including blood levels of IgE, CCL17/TARC, lactate dehydrogenase (LDH) and eosinophil counts, and concentration levels of serum Th1/Th2 cytokines. Filaggrin (FLG) mutations were examined in 21 patients. These values were subjected to correlation analyses with each of the four sensation elements.

RESULTS

According to the standard criteria for LAST positivity, the frequencies of LAST-positive subjects were 54.8% and 10.0% in AD and HS, respectively (P=0.014). EAD patients showed a significantly (P=0.026) higher frequency of positive LAST (65.6%) than did IAD patients (20.0%). Among the four LAST sensation elements, the crawly feeling and pain scores positively correlated with VAS of pruritus, total serum IgE, mite-specific IgE, CCL17/TARC, and/or LDH. There was no association of the LAST scores with serum Th1/Th2 cytokine levels. Notably, neither TEWL nor FLG mutations correlated with LAST positivity or any sensation scores.

CONCLUSIONS

The frequency of sensitive skin is higher in EAD than in IAD. Sensitive skin is associated with AD severity, but not necessarily with barrier condition.

Cellular and molecular immunologic mechanisms in patients with atopic dermatitis

Atopic dermatitis (AD) is a complex skin disease frequently associated with other diseases of the atopic diathesis. Recent evidence supports the concept that AD can also recognize other comorbidities, such as chronic inflammatory bowel or cardiovascular diseases. These comorbidities might result from chronic cutaneous inflammation or from a common, yet-to-be-defined immunologic background leading to immune deviations. The activation of immune cells and their migration to the skin play an essential role in the pathogenesis of AD. In patients with AD, an underlying immune deviation might result in higher susceptibility of the skin to environmental factors. There is a high unmet medical need to define immunologic endotypes of AD because it has significant implications on upcoming stratification of the phenotype of AD and the resulting targeted therapies in the development of precision medicine. This review article emphasizes studies on environmental factors affecting AD development and novel biological agents used in the treatment of AD. Best evidence of the clinical efficacy of novel immunologic approaches using biological agents in patients with AD is available for the anti-IL-4 receptor α-chain antibody dupilumab, but a number of studies are currently ongoing with other specific antagonists to immune system players. These targeted molecules can be expressed on or drive the cellular players infiltrating the skin (eg, T lymphocytes, dendritic cells, or eosinophils). Such approaches can have immunomodulatory and thereby beneficial clinical effects on the overall skin condition, as well as on the underlying immune deviation that might play a role in comorbidities. An effect of these immunologic treatments on pruritus and the disturbed microbiome in patients with AD has other potential consequences for treatment.

Expression of IL-22 in the Skin Causes Th2-Biased Immunity, Epidermal Barrier Dysfunction, and Pruritus via Stimulating Epithelial Th2 Cytokines and the GRP Pathway

Increased expression of Th22 cytokine IL-22 is a characteristic finding in atopic dermatitis (AD). However, the specific role of IL-22 in the pathogenesis of AD in vivo has yet to be elucidated. Consistent with observations in human AD, IL-22 was significantly increased in the AD skin of mice after epicutaneous sensitization to house dust mite allergen. Utilizing a skin-specific inducible transgenic system, we show in the present study that expression of IL-22 in the skin of mice caused an AD-like phenotype characterized by chronic pruritic dermatitis associated with Th2-biased local and systemic immune responses, downregulation of epidermal differentiation complex genes, and enhanced dermatitis upon epicutaneous allergen exposure. IL-22 potently induced the expression of gastrin-releasing peptide (GRP), a neuropeptide pruritogen, in dermal immune cells and sensory afferents and in their skin-innervating sensory neurons. IL-22 also differentially upregulated the expression of GRP receptor (GRPR) on keratinocytes of AD skin. The number of GRP+ cells in the skin correlated with the AD severity and the intensity of pruritus. IL-22 directly upregulated the expression of epithelial-derived type 2 cytokines (thymic stromal lymphopoietin and IL-33) and GRP in primary keratinocytes. Furthermore, GRP not only strongly induced thymic stromal lymphopoietin but it also increased the expression of IL-33 and GRPR synergistically with IL-22. Importantly, we found that the expression of GRP was strikingly increased in the skin of patients with AD. These results indicate that IL-22 plays important pathogenic roles in the initiation and development of AD, in part through inducing keratinocyte production of type 2 cytokines and activation of the GRP/GRPR pathway.

Antipruritic Effect of Cold-induced and Transient Receptor Potential-agonist-induced Counter-irritation on Histaminergic Itch in Humans

A frequent empirical observation is that cold-induced counter-irritation may attenuate itch. The aim of this randomized, single-blinded, exploratory study was to evaluate the counter-irritation effects of cold-stimulation and topical application of transient receptor potential TRPA1/M8-agonists (trans-cinnamaldehyde/L-menthol, respectively), on histamine-induced itch, wheals and neurogenic inflammation in 13 healthy volunteers. Histamine 1% was applied to the volar forearms using skin prick-test lancets. Recorded outcome-parameters were itch intensity, wheal reactions, and neurogenic inflammation (measured by laser-speckle perfusion-imaging). Homotopic thermal counter-irritation was performed with 6 temperatures, ranging from 4°C to 37°C, using a 3 × 3-cm thermal stimulator. Chemical "cold-like" counter-irritation was conducted with 40% L-menthol and 10% trans-cinnamaldehyde, while 5% doxepin was used as a positive antipruritic control/comparator. Cold counter-irritation stimuli from 4°C to 22°C inhibited itch in a stimulus-intensity-dependent manner (p < 0.05) and, to a lesser extent, also wheal reactions and neurogenic inflammation. Chemical "cold-like" counter-irritation with both L-menthol and trans-cinnamaldehyde had antipruritic efficacy similar to doxepin (p < 0.05). Cold-induced counter-irritation had an inhibitory effect on histaminergic itch, suggesting that agonists of cold transduction receptors could be of potential antipruritic value.

Early Activation of Th2/Th22 Inflammatory and Pruritogenic Pathways in Acute Canine Atopic Dermatitis Skin Lesions

Determining inflammation and itch pathway activation in patients with atopic dermatitis (AD) is fraught with the inability to precisely assess the age of skin lesions, thus affecting the analysis of time-dependent mediators. To characterize inflammatory events occurring during early experimental acute AD lesions, biopsy samples were collected 6, 24, and 48 hours after epicutaneous application of Dermatophagoides farinae house dust mites to sensitized atopic dogs. The skin transcriptome was assessed using a dog-specific microarray and quantitative PCR. Acute canine AD skin lesions had a significant up-regulation of genes encoding T helper (Th) 2 (e.g., IL4, IL5, IL13, IL31, and IL33), Th9 (IL9), and Th22 (IL22) cytokines as well as Th2-promoting chemokines such as CCL5 and CCL17. Proinflammatory (e.g., IL6, LTB, and IL18) cytokines were also up-regulated. Other known pruritogenic pathways were also activated: there was significant up-regulation of genes encoding proteases cathepsin S (CTSS), mast cell chymase (CMA1), tryptase (TPS1) and mastin, neuromedin-B (NMB), nerve growth factor (NGF), and leukotriene-synthesis enzymes (ALOX5, ALOX5AP, and LTA4H). Experimental acute canine house dust mite-induced AD lesions exhibit an activation of innate and adaptive immune responses and pruritogenic pathways similar to those seen in humans with acute AD, thereby validating this model to test innovative therapeutics modalities for this disease.

Serotonergic Markers in Atopic Dermatitis

Stress and anxiety may worsen atopic dermatitis (AD) through the serotonin system. Serotonergic expression was measured in 28 patients with AD in relation to extent of the disease (SCORing of Atopic Dermatitis; SCORAD), pruritus intensity (visual analogue scale; VAS), anxiety traits (Swedish Universities Scales of Personality; SSP) and depression (Montgomery-Åsberg Depression Rating Scale-Self assessment; MADRS-S). Biopsies were taken from lesional and non-lesional AD skin, and investigated for expression of serotonin, its receptors 5-HT1A and 5-HT2, and serotonin transporter protein (SERT), using immunohistochemistry. 5-HT1AR-immunoreactivity (ir) was higher in lesional skin in apical epidermis and in mast cell-like cells in dermis, and 5-HT2AR-ir in apical epidermis and on blood vessels. In contrast, a basement membrane 5-HT2AR-ir signal was higher in non-lesional skin. The distribution of SERT-ir in the basal epidermal layer was higher in lesional skin. Positive and negative correlations were found between serotonergic markers and SCORAD, inflammation, pruritus intensity, anxiety traits, and depression score, indicating that serotonergic mechanisms are involved in AD.

Peripheral Mechanisms of Itch

A multitude of exogenous environmental stimuli and endogenous molecular and cellular components interface directly or indirectly with the free nerve endings of sensory nerves in the skin. Environmental stimuli include substances derived from the microbiome and materials, such as allergens, that otherwise come in contact with the skin. Endogenous stimuli include components of or mediators derived from the epidermal barrier, keratinocytes, mast cells, and additional resident and skin-homing immune cells. The sensation of itch is ultimately provoked by mediators that interact with and activate pruriceptors on the sensory nerve fibers. These peripheral fibers convey signals from the skin to the dorsal root and trigeminal ganglia and on to the spinal cord and brain where central processing of the itch sensation occurs. A discussion of the nature and sources of itch stimuli and receptors in the periphery form the basis of this chapter. The development of drugs that target these processes is in the process of revolutionizing therapeutic approaches to itch.

Ultra-pure soft water ameliorates atopic skin disease by preventing metallic soap deposition in NC/Tnd mice and reduces skin dryness in humans

Mineral ions in tap water react with fatty acids in soap, leading to the formation of insoluble precipitate (metallic soap) on skin during washing. We hypothesised that metallic soap might negatively alter skin conditions. Application of metallic soap onto the skin of NC/Tnd mice with allergic dermatitis further induced inflammation with elevation of plasma immunoglobulin E and proinflammatory cytokine expression. Pruritus and dryness were ameliorated when the back of mice was washed with soap in Ca2+- and Mg2+-free ultra-pure soft water (UPSW). Washing in UPSW, but not tap water, also protected the skin of healthy volunteers from the soap deposition. Furthermore, 4 weeks of showering with UPSW reduced dryness and pruritus of human subjects with dry skin. Washing with UPSW may be therapeutically beneficial in patients with skin troubles.

Human surrogate models of histaminergic and non-histaminergic itch

Within the last decade understanding of the mechanistic basis of itch has improved significantly, resulting in the development of several human surrogate models of itch and related dysesthetic states. Well-characterized somatosensory models are useful in basic studies in healthy volunteers, in clinical studies for diagnostic and segmentation purposes, and in pharmacological studies to evaluate the antipruritic efficacy of existing and novel compounds. This review outlines recently introduced histamine-independent human models of itch, their mechanisms, their ability to induce clinically relevant phenomena, such as alloknesis, and the results obtained through their use. The article also introduces recent advances in the understanding of itch and provides an overview of the methods to assess experimentally-induced itch and associated manifestations. Major improvements are warranted in the treatment of chronic pruritus, and reliable human surrogate models are a valuable tool in achieving them, both for basic researchers and for clinicians.

Role of cytokines and chemokines in itch

Cytokines classically are secreted "messenger" proteins that modulate cellular function of immune cells. Chemokines attract immune cells to the site where they exert various functions in inflammation, autoimmunity or cancer. Increasing evidence is emerging that cytokines or chemokines can act as "neuro-modulators" by activating high-affinity receptors on peripheral or central neurons, microglia cells or Schwann cells. Very recently, cytokines have been shown to act as pruritogens in rodents and humans, while a role of chemokines in itch has thus far been only demonstrated in mice. Upon stimulation, cytokines are released by skin or immune cells and form a "bridge of communication" between the immune and nervous system. For some cytokines such as IL-31 and TSLP, the evidence for this role is strong in rodents. For cytokines such as IL-4, there is some convincing evidence, while for cytokines such as oncostatin M, IL-2, IL-6, IL-8 and IL-13, direct evidence is currently limited. Current clinical trials support the idea that cytokines and chemokines and their receptors or signalling pathways are promising targets for the future therapy of certain subtypes of itch.

[Aluminium allergy and granulomas induced by vaccinations for children]

Vaccination with aluminium-adsorbed vaccines can induce aluminium allergy with persistent itching subcutaneous nodules at the injection site – vaccination granulomas. In this article we give an overview of childhood aluminium-adsorbed vaccines available in Denmark. Through literature studies we examine the incidence, the symptoms and the prognosis for the vaccination granulomas and the allergy. Finally we discuss the status in Denmark.

Prostanoids in allergy

Prostanoids, which include prostaglandin and thromboxane, are metabolites of arachidonic acid released in various pathophysiological conditions. They induce a range of actions mediated through their respective receptors expressed on target cells. It has been demonstrated that each prostanoid receptor has multiple functions and that the effect of receptor stimulation can vary depending on context; this sometimes results in opposing effects, such as simultaneous excitatory and inhibitory outcomes. The balance between the production of each prostanoid and the expression of its receptors has been shown to be important for maintaining homeostasis but also involved in the development of various pathological conditions such as allergy. Here, we review the recent findings on the roles of prostanoids in allergy, especially focusing on atopic dermatitis and asthma.

Atopic dermatitis in children: clinical features, pathophysiology, and treatment

Atopic dermatitis (AD) is a chronic, relapsing, highly pruritic skin condition resulting from disruption of the epithelial barrier and associated immune dysregulation in the skin of genetically predisposed hosts. AD generally develops in early childhood, has a characteristic age-dependent distribution and is commonly associated with elevated IgE, peripheral eosinophilia, and other allergic diseases. Medications such as antihistamines have demonstrated poor efficacy in controlling AD-associated itch. Education of patients regarding the primary underlying defects and provision of a comprehensive skin care plan is essential for disease maintenance and management of flares.