Atopic dermatitis: beyond the itch that rashes

Diisocyanates influence models of atopic dermatitis through direct activation of TRPA1

We recently used EPA databases to identify that isocyanates, most notably toluene diisocyanate (TDI), were the pollutant class with the strongest spatiotemporal and epidemiologic association with atopic dermatitis (AD). Our findings demonstrated that isocyanates like TDI disrupted lipid homeostasis and modeled benefit in commensal bacteria like Roseomonas mucosa through disrupting nitrogen fixation. However, TDI has also been established to activate transient receptor potential ankyrin 1 (TRPA1) in mice and thus could directly contribute to AD through induction of itch, rash, and psychological stress. Using cell culture and mouse models, we now demonstrate that TDI induced skin inflammation in mice as well as calcium influx in human neurons; each of these findings were dependent on TRPA1. Furthermore, TRPA1 blockade synergized with R. mucosa treatment in mice to improve TDI-independent models of AD. Finally, we show that the cellular effects of TRPA1 are related to shifting the balance of the tyrosine metabolites epinephrine and dopamine. This work provides added insight into the potential role, and therapeutic potential, or TRPA1 in the pathogenesis of AD.

Extracellular Vesicles from SOD3-Transduced Stem Cells Exhibit Improved Immunomodulatory Abilities in the Murine Dermatitis Model

The immunoregulatory abilities of mesenchymal stem cells (MSCs) have been investigated in various autoimmune and allergic diseases. However, the therapeutic benefits observed in preclinical settings have not been reproducible in clinical trials. This discrepancy is due to insufficient efficacy of MSCs in harsh microenvironments, as well as batch-dependent variability in potency. Therefore, to achieve more beneficial and uniform outcomes, novel strategies are required to potentiate the therapeutic effect of MSCs. One of simple strategies to augment cellular function is genetic manipulation. Several studies showed that transduction of antioxidant enzyme into cells can increase anti-inflammatory effects. Therefore, we evaluated the immunoregulatory abilities of MSCs introduced with extracellular superoxide dismutase 3 (SOD3) in the present study. SOD3-overexpressed MSCs (SOD3-MSCs) reduced the symptoms of murine model of atopic dermatitis (AD)-like inflammation, as well as the differentiation and activation of various immune cells involved in AD progression. Interestingly, extracellular vesicles (EVs) isolated from SOD3-MSCs delivered SOD3 protein. EVs carrying SOD3 also exerted improved therapeutic efficacy, as observed in their parent cells. These results suggest that MSCs transduced with SOD3, an antioxidant enzyme, as well as EVs isolated from modified cells, might be developed as a promising cell-based therapeutics for inflammatory disorders.

Management of Itch in Atopic Dermatitis

Atopic dermatitis (AD) is the most common itchy dermatosis that affects millions of children and adults worldwide. Chronic itch in this condition has significant impact on measures of quality of life, such as sleep. Treating itch in AD has been challenging for decades, but new drugs have emerged in the last year with significant anti-pruritic effect. The optimal treatment regimen for atopic itch addresses barrier dysfunction, inflammation, neural hypersensitivity, and the itch-scratch cycle. Topical moisturizers remain the foundation of treatment and should be used by all patients with AD-associated pruritus. Step-wise therapy, from topical anti-inflammatory creams to systemic monoclonal antibodies and immunosuppressants, is recommended. There are multiple adjuvant therapies that can be used, especially to target itch in the setting of minimal skin inflammation. Finally, patient education, sleep management, and stress relief are important components to optimize outcomes. This review assesses the latest advances and treatment recommendations for pruritus in AD. Finally, suggested therapeutic ladders and emerging treatments are discussed.

Emerging Roles for MAS-Related G Protein-Coupled Receptor-X2 in Host Defense Peptide, Opioid, and Neuropeptide-Mediated Inflammatory Reactions

Mast cells (MCs) are tissue-resident immune cells that contribute to host defense but are best known for their roles in allergic and inflammatory diseases. In humans, MCs are divided into two subtypes based on the protease content of their secretory granules. Thus, human lung MCs contain only tryptase and are known as MC_T, whereas skin MCs contain both tryptase and chymase and are known as MC_TC. Patients with severe asthma display elevated MCs in the lung, which undergo phenotypic change from MC_T to MC_TC. Although the human genome contains four Mas related G protein coupled receptor X (MRGPRX) genes, an important feature of MC_TC is that they selectively express MRGPRX2. It is activated by antimicrobial host defense peptides such as human β-defensins and the cathelicidin LL-37 and likely contributes to host defense. MRGPRX2 is also a receptor for the neuropeptide substance P, major basic protein, eosinophil peroxidase, opioids, and many FDA-approved cationic drugs. Increased expression of MRGPRX2 or enhanced downstream signaling likely contributes to chronic inflammatory diseases such as rosacea, atopic dermatitis, chronic urticaria, and severe asthma. In this chapter, I will discuss the expression profile and function of MRGPRX1-4 and review the emerging roles of MRGPRX2 on host defense, chronic inflammatory diseases, and drug-induced pseudoallergic reactions. I will also examine the novel aspects of MRGPRX2 signaling in MCs as it related to degranulation and review the mechanisms of its regulation.

Sleep patterns of young children with newly diagnosed atopic dermatitis

Introduction

Even though atopic dermatitis (AD) most often begins in the first year of life, it is not well known whether sleep disturbances occur following the onset of the disease or whether they develop later.

Aim

To determine the sleep patterns of young children already diagnosed with AD in comparison to a control group by using a validated questionnaire, the Brief Infant Sleep Questionnaire (BISQ).

Material and methods

Forty-six children with a new diagnosis of AD and 60 healthy children, aged 3–36 months, participated in the study. Their sleep behaviors were assessed using the BISQ along with a structured sociodemographic data form.

Results

It was found that when compared with healthy children, children with AD did not have decreased daily total sleep duration (p = 0.1); however, it was found that they woke up more frequently at night (52.2% vs. 40%, p = 0.4) and they stayed awake significantly longer than 60 min when they woke up (41.3% vs. 11.7%, p < 0.05). In addition, mothers of children with AD reported that their children had three times as many sleep problems compared to the reports of mothers of healthy children.

Conclusions

The findings of this study showed that sleep disturbance was more common in young children with already diagnosed AD, and the BISQ provided a practical way to assess the sleep patterns. The use of a screening tool to enable early identification and treatment of childhood sleep problems among patients with AD should be encouraged.

Human umbilical cord blood mesenchymal stem cell-derived PGE2 and TGF-β1 alleviate atopic dermatitis by reducing mast cell degranulation

Mesenchymal stem cell (MSC) is a promising tool for the therapy of immune disorders. However, their efficacy and mechanisms in treating allergic skin disorders are less verified. We sought to investigate the therapeutic efficacy of human umbilical cord blood-derived MSCs (hUCB-MSCs) against murine atopic dermatitis (AD) and to explore distinct mechanisms that regulate their efficacy. AD was induced in mice by the topical application of Dermatophagoides farinae. Naïve or activated-hUCB-MSCs were administered to mice, and clinical severity was determined. The subcutaneous administration of nucleotide-binding oligomerization domain 2 (NOD2)-activated hUCB-MSCs exhibited prominent protective effects against AD, and suppressed the infiltration and degranulation of mast cells (MCs). A β-hexosaminidase assay was performed to evaluate the effect of hUCB-MSCs on MC degranulation. NOD2-activated MSCs reduced the MC degranulation via NOD2-cyclooxygenase-2 signaling. In contrast to bone marrow-derived MSCs, hUCB-MSCs exerted a cell-to-cell contact-independent suppressive effect on MC degranulation through the higher production of prostaglandin E2 (PGE2 ). Additionally, transforming growth factor (TGF)-β1 production from hUCB-MSCs in response to interleukin-4 contributed to the attenuation of MC degranulation by downregulating FcεRI expression in MCs. In conclusion, the subcutaneous application of NOD2-activated hUCB-MSCs can efficiently ameliorate AD, and MSC-derived PGE2 and TGF-β1 are required for the inhibition of MC degranulation.

The brain circuitry mediating antipruritic effects of acupuncture

Itch is an aversive sensory experience and while systemic therapies, such as acupuncture, have shown promise in alleviating itch in patients suffering from chronic itch, their antipruritic mechanisms are unknown. As several lines of evidence implicate brain-focused mechanisms, we applied functional magnetic resonance imaging and our validated temperature-modulation itch model to evaluate the underlying brain circuitry supporting allergen-induced itch reduction in atopic dermatitis patients by acupuncture, antihistamine, and respective placebo treatments. Brain response to allergen itch demonstrated phase dependency. During an increasing itch phase, activation was localized in anterior insula and striatum, regions associated with salience/interoception and motivation processing. Once itch reached peak plateau, robust activation was noted in prefrontal cognitive and premotor areas. Acupuncture reduced itch and itch-evoked activation in the insula, putamen, and premotor and prefrontal cortical areas. Neither itch sensation nor itch-evoked brain response was altered following antihistamine or placebo acupuncture. Greater itch reduction following acupuncture was associated with greater reduction in putamen response, a region implicated in motivation and habitual behavior underlying the urge to scratch, specifically implicating this region in acupuncture's antipruritic effects. Understanding brain circuitry underlying itch reduction following acupuncture and related neuromodulatory therapies will significantly impact the development and applicability of novel therapies to reduce an itch.

Presentation of atopic disease in a large cohort of pediatric liver transplant recipients

Atopic disease occurs in solid organ transplant recipients with an increasingly recognized frequency. The time course for the development of these atopic diseases in liver transplantation has not been described. The objective was to characterize the atopic manifestations of children receiving chronic immunosuppression after orthotopic liver transplantation (OLT). Chart review and follow-up questionnaire were utilized for 176 OLT pediatric recipients at a single institution for manifestations of allergic disease. Atopic disease was present in 25 (14.2%) patients. Median age at transplant was 16 months with a median follow-up of 63 months. Food allergy and non-food related atopic symptoms presented at a median of 11.5 (IQR, 6-28) and 19 (IQR, 5-41) months post-transplantation, respectively. The median age at transplant of the non-atopic children was 72 months, higher than patients with atopy (p < 0.001). Food allergy and atopic skin disease symptoms were present in 40% and 56% of cases, respectively. Asthma, allergic rhinitis, or both were found in 66% of cases. The onset of symptoms of food allergy and eczema (median, 12 months post-transplantation) preceded symptoms of allergic rhinitis and asthma. (median of 27 and 30 months post-transplantation, respectively). Atopy occurs in ∼14% of pediatric liver transplant recipients, with manifestations including food allergy, eczema, allergic rhinitis, and asthma.

Evaluation of itch by using NC/NgaTnd mice: a model of human atopic dermatitis

Atopic dermatitis (AD) is the extremely complicated syndrome that various abnormalities develop in a heap. There are various factors in patients for the onset and exacerbation of AD, including genetic cofactors of individuals, environmental factors, the failure of the skin barrier function, unfavorable regulation of the immune system, and the hypersensitivity of sensory nerves. In recent years, there have been many trials of the drug discovery that targets itch, because itch is one of the most serious clinical symptoms of AD. The selection of the suitable animal model that represents the condition of patients, as well as innovative analyzing protocols that can precisely evaluate itch, is indispensable for investigation of an effective drug for AD. In the paper, the unique spontaneous animal model for AD (NC/NgaTnd mice) and the novel quantification system of the laboratory animals that may bring a great progress in the future study of itch are outlined.

Anti-immunoglobulin e in the treatment of refractory atopic dermatitis

Atopic dermatitis (AD) is a common diagnosis seen in both children and adults, and it is often the first manifestation of atopic disease. Research has shown a strong correlation between serum IgE levels, the severity of atopic dermatitis, and co-existing asthma and/or allergic rhinitis. Omalizumab (Xolair, East Hanover, NJ; Genentech, South San Francisco, CA) is a monoclonal antibody to human IgE and is currently Food and Drug Administration (FDA) approved for the treatment of asthma. We present 3 patients with severe, treatment resistant atopic dermatitis whose cutaneous symptoms significantly improved by treatment with omalizumab.

Oral supplementation with Lactobacillus rhamnosus CGMCC 1.3724 prevents development of atopic dermatitis in NC/NgaTnd mice possibly by modulating local production of IFN-gamma

Prevalence of allergies has increased during the last two decades. Alteration of the gut microbiota composition is thought to play a crucial role in development of atopic diseases. Oral administration of probiotics has been reported to treat and/or prevent symptoms of atopic diseases in infants, but the results are still controversial. We investigated the potential efficacy of dietary interventions by a probiotic strain on prevention and treatment of atopic dermatitis (AD) in a human-like AD model, NC/NgaTnd mice by perinatal administration. Pregnant NC/NgaTnd mice were orally treated with the probiotic strain Lactobacillus rhamnosus CGMCC 1.3724 (LPR), which was followed by treatment of pups until 12 weeks of age. LPR-treated mice exhibited significant lower clinical symptoms of dermatitis, reduced scratching frequency, lower levels of plasma total Immunoglobulin E and higher levels of interferon-gamma in skin biopsies, compared with untreated mice. The protective effect was also observed when mice started to be treated at weaning time (5 weeks of age) even with limited supplementation period of 2 weeks. However, treatment of mice with the probiotic starting 1 week after the onset of the disease (8 weeks of age) had limited effects. The usefulness of LPR for primary prevention of AD was supported.

Skin disorders and sleep in adults: where is the evidence?

Sleep deprivation has been shown to have detrimental effects on behavioural, physiological and psychological functioning. Skin disorders are variably associated with sleep disturbance and sleep deprivation, some associated with specific sleep disorders such as obstructive sleep apnoea. Paradoxically, there is very little literature focussed on the management of sleep problems in the context of skin disorders. Furthermore, randomised controlled trials of treatments for skin conditions are few and rarely measure sleep as an outcome, either subjectively or objectively. This review focuses on common skin disorders and how they affect sleep.

Injury downregulates the expression of the human cathelicidin protein hCAP18/LL-37 in atopic dermatitis

Reduced production of antimicrobial peptides was proposed to contribute to susceptibility for skin infections in atopic dermatitis (AD). Focusing on the human cathelicidin protein, hCAP18, the aim of the present study was to explore whether reduced hCAP18 expression is a constitutive trait in AD and if established inducers affect the expression of hCAP18 in the skin of AD. First, we compared levels of hCAP18 mRNA between lesional skin in AD and psoriasis and verified significantly lower expression of hCAP18 mRNA in AD. In non-lesional skin, however, there was no difference between AD, psoriasis and healthy, indicating that there is no constitutive defect in the production of hCAP18 in AD patients. In healthy skin, hCAP18 was reported to be rapidly induced following wounding and here we verified this pattern in healthy controls and in psoriasis. In AD lesions, however, the expression of hCAP18 mRNA was markedly suppressed following wounding. Obviously, the inflammation in AD lesions neutralizes the expected induction of hCAP18 and even induces suppression. Notably, the mechanism to upregulate hCAP18 following vitamin D treatment was functional in lesional as well as in non-lesional AD indicating that the CAMP gene is normally regulated in this respect. In addition, cultured primary keratinocytes from non-lesional skin of psoriasis, AD and healthy skin, upregulated hCAP18mRNA following treatment with vitamin D. Itching is a hallmark of AD and scratching inevitably injures the skin. Failure to upregulate hCAP18 in eczema following injury is likely to affect antimicrobial protection and tissue repair in AD.

Predicting risk for early infantile atopic dermatitis by hereditary and environmental factors

BACKGROUND

Hereditary and environmental factors contribute to the occurrence of atopic dermatitis (AD). However, the interaction of these two factors is not totally understood.

OBJECTIVES

To evaluate the early risk factors for infantile AD at the age of 6 months and to develop a predictive model for the development of AD.

METHODS

In 2005, a representative sample of mother and newborn pairs was obtained by multistage, stratified systematic sampling from the Taiwan national birth register. Information on hereditary and environmental risk factors was collected by home interview when babies were 6 months old. Multivariate regression analysis was applied to determine the risk factors for AD in the infants.

RESULTS

A total of 20 687 pairs completed the study satisfactorily. AD was diagnosed in 7.0% of 6-month-old infants by physicians. Parental asthma, atopic dermatitis and allergic rhinitis, and maternal education levels were risk factors for AD in infants. Among environmental factors, fungus on walls at home and renovation/painting in the house during pregnancy were significantly associated with early infantile AD. Using these factors, the probability of having infantile AD was estimated and grouped into low, high and very high. With five runs of tests in mutually exclusive subsets of this population, the likelihood of AD for 6-month-old infants was consistent in all the groups with the predictive model. The highest predicted probability of AD was 70.1%, among boys with maternal education levels > 12 years, both parents with AD, renovation and painting of the house during pregnancy and fungus on walls at home. The lowest probability was 3.1%, among girls with none of the above factors.

CONCLUSIONS

This investigation provides a technique for predicting the risk of infantile AD based on hereditary and environmental factors, which could be used for developing a preventive strategy against AD, especially among those children with a family history of atopy.

Distinct patterns of brain activity evoked by histamine-induced itch reveal an association with itch intensity and disease severity in atopic dermatitis

BACKGROUND

Little is known about brain mechanisms supporting the experience of chronic puritus in disease states.

OBJECTIVES

To examine the difference in brain processing of histamine-induced itch in patients with active atopic dermatitis (AD) vs. healthy controls with the emerging technique of functional magnetic resonance imaging (fMRI) using arterial spin labelling (ASL).

METHODS

Itch was induced with histamine iontophoresis in eight patients with AD and seven healthy subjects.

RESULTS

We found significant differences in brain processing of histamine-induced itch between patients with AD and healthy subjects. Patients with AD exhibited bilateral activation of the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), retrosplenial cingulate cortex and dorsolateral prefrontal cortex (DLPFC) as well as contralateral activation of the caudate nucleus and putamen. In contrast, healthy subjects activated the primary motor cortex, primary somatosensory cortex and superior parietal lobe. The PCC and precuneus exhibited significantly greater activity in patients vs. healthy subjects. A significant correlation between percentage changes of brain activation was noted in the activation of the ACC and contralateral insula and histamine-induced itch intensity as well as disease severity in patients with AD. In addition, an association was noted between DLPFC activity and disease severity.

CONCLUSIONS

Our results demonstrate that ASL fMRI is a promising technique to assess brain activity in chronic itch. Brain activity of acute itch in AD seems to differ from that in healthy subjects. Moreover, the activity in cortical areas involved in affect and emotion correlated to measures of disease severity.

What causes itch in atopic dermatitis?

Itch, the hallmark of atopic dermatitis, has a significant impact on quality of life for patients with this disease. Various central and peripheral mediators have been suggested to play a role in the pathophysiology of atopic eczema itch. Significant cross-talk occurs among stratum corneum, keratinocytes, immune cells, and nerve fibers, which are in close proximity to one another and induce itch. The impaired barrier function associated with the itch-scratch cycle further augments this vicious cycle. Recent advances in our understanding of itch pathophysiology shed light on peripheral and central neural sensitization of nerve fibers that contribute significantly to itch in atopic dermatitis. Recently, several new mediators have been described as associated with itch in atopic dermatitis, including serine proteases, interleukin 31, and nerve growth factor. This review covers the peripheral and central mechanisms and mediators involved in pathogenesis of itch in atopic dermatitis.

Topical application with a new NF-kappaB inhibitor improves atopic dermatitis in NC/NgaTnd mice

Growing evidence has demonstrated the crucial role of NF-kappaB activation on disease severity in allergic disorders. In this study, we examined the clinical relevance of a novel NF-kappaB inhibitor, IMD-0354, for atopic dermatitis (AD) by its topical application. To investigate the in vivo efficacy, 1% IMD-0354 ointment was applied daily to NC/NgaTnd mice with severe dermatitis, which served as a model for human AD. During 2 weeks of treatment, scratching behavior decreased and severity of dermatitis reduced in mice treated with IMD-0354 as well as FK506 without diverse effects. Based on histological examinations, the hyperplasia of keratinocytes and infiltration of inflammatory cells were significantly reduced in the skin of IMD-0354-treated mice. The expressions of T-helper 2 cytokines and tumor necrosis factor-alpha at the affected skin sites were downregulated in IMD-0354-treated mice. Furthermore, IMD-0354 suppressed the proliferation of various immunocompetent cells, neurite outgrowth of nerve growth factor-stimulated pheochromocytoma cells, IgE production from splenic B cells, and IgE-mediated activation of mast cells in vitro. IMD-0354 effectively reduced the allergic inflammation in NC/NgaTnd mice in vivo. Thus, a drug that interferes with NF-kappaB activity may provide an alternative therapeutic strategy for the treatment of AD.

Joint effect of asthma/atopy and an IL-6 gene polymorphism on lung cancer risk among lifetime non-smoking Chinese women

Recent evidence suggests that inflammatory pathways are important mediators of carcinogenesis. Asthma, allergic rhinitis and atopic dermatitis are clinical manifestations of a systemic atopic disorder, which is associated with airway hyper-responsiveness and inflammation. We examined the effect of a history of asthma/atopy among 132 lung cancer cases (of which 72% were adenocarcinomas) and 163 controls, all of whom were non-smoking Chinese women, in combination with a single nucleotide polymorphism (-634C/G) in the interleukin-6 (IL-6) gene which regulates secretion of a pro-inflammatory cytokine found to be predominant in lung tumour tissue. We observed a slight increase in risk of lung cancer [odds ratio, OR = 1.5, 95% confidence interval (95% CI) = 0.8-2.6] and of adenocarcinoma (OR = 1.6, 95% CI = 0.9-3.1) with asthma/atopy alone. There was no effect of the IL-6 CG/GG genotype on lung cancer risk on its own. Among individuals with both asthma/atopy and the IL-6 -634 G allele, however, risk was increased at least 3-fold (OR = 3.1, 95% CI = 1.2-8.3 for all cancers and OR = 4.2, 95% CI = 1.5-11.6 for adenocarcinomas) relative to individuals with no asthma/atopy and the CC genotype. On stratified analysis, a significant increase in risk with asthma/atopy was restricted to those with the at-risk genotype (Pint < 0.05). Our findings are consistent with the role of chronic inflammation as an aetiologic factor among non-smoking Asian women, and suggest that asthma/atopy is a risk marker for susceptibility to the development of lung cancer.