Extrinsic and intrinsic types of atopic dermatitis

Cyclosporin A Treatment in Intrinsic Canine Atopic Dermatitis (Atopic-like Dermatitis): Open Trial Study

In this study, dogs were separated into two groups and treated with immunosuppressant (Cyclosporin A: CsA). The first group was the canine atopic dermatitis (CAD) group, which is similar to extrinsic atopic dermatitis (AD) in humans (treated with a CsA dose of 2.5-5.5 mg/kg, n=8), and the second group was the canine atopic-like dermatitis (ALD) group, which is similar to intrinsic AD in humans (treated with a CsA dose of 2.5-6.5 mg/kg, n=14). The canine atopic dermatitis extent and severity index (CADESI)-4 was evaluated before treatment (PRE) and after treatment (POST) to assess the effectiveness of CsA for the two groups. In the CAD group, CADESI-4 showed no change (PRE:79±29, POST:77±28) and out of the eight dogs, no dogs showed complete remission, three dogs showed partial remission, and five dogs showed no effect. Whereas in the ALD group, CADESI-4 showed a significant reduction (PRE: 61±42, POST: 32±25, p<0.01) and out of the 14 dogs, 11 dogs showed complete remission, two dogs showed partial remission, and one dog showed no effect. The results indicate that the immunosuppressant showed effectiveness for the dogs diagnosed with ALD. One dog had to be treated for a year and eight months, which was the longest period in the study, this dog presented with hyperplasia of the lymphoidgland and mammary tumor.

Molecular Mechanisms of Cutaneous Inflammatory Disorder: Atopic Dermatitis

Atopic dermatitis (AD) is a multifactorial inflammatory skin disease resulting from interactions between genetic susceptibility and environmental factors. The pathogenesis of AD is poorly understood, and the treatment of recalcitrant AD is still challenging. There is accumulating evidence for new gene polymorphisms related to the epidermal barrier function and innate and adaptive immunity in patients with AD. Newly-found T cells and dendritic cell subsets, cytokines, chemokines and signaling pathways have extended our understanding of the molecular pathomechanism underlying AD. Genetic changes caused by environmental factors have been shown to contribute to the pathogenesis of AD. We herein present a review of the genetics, epigenetics, barrier dysfunction and immunological abnormalities in AD with a focus on updated molecular biology.

IgE Sensitization Profiles Differ between Adult Patients with Severe and Moderate Atopic Dermatitis

Background

Atopic dermatitis (AD) is a complex chronic inflammatory disease where allergens can act as specific triggering factors.

Aim

To characterize the specificities of IgE-reactivity in patients with AD to a broad panel of exogenous allergens including microbial and human antigens.

Methodology

Adult patients with AD were grouped according to the SCORAD index, into severe (n = 53) and moderate AD (n = 126). As controls 43 patients were included with seborrhoeic eczema and 97 individuals without history of allergy or skin diseases. Specific IgE reactivity was assessed in plasma using Phadiatop^®, ImmunoCap^™, micro-arrayed allergens, dot-blotted recombinant Malassezia sympodialis allergens, and immune-blotted microbial and human proteins.

Results

IgE reactivity was detected in 92% of patients with severe and 83% of patients with moderate AD. Sensitization to cat allergens occurred most frequently, followed by sensitization to birch pollen, grass pollen, and to the skin commensal yeast M. sympodialis. Patients with severe AD showed a significantly higher frequency of IgE reactivity to allergens like cat (rFel d 1) and house dust mite (rDer p 4 and 10), to Staphylococcus aureus, M. sympodialis, and to human antigens. In contrast, there were no significant differences in the frequencies of IgE reactivity to the grass pollen allergens rPhl p 1, 2, 5b, and 6 between the two AD groups. Furthermore the IgE reactivity profile of patients with severe AD was more spread towards several different allergen molecules as compared to patients with moderate AD.

Conclusion

We have revealed a hitherto unknown difference regarding the molecular sensitization profile in patients with severe and moderate AD. Molecular profiling towards allergen components may provide a basis for future investigations aiming to explore the environmental, genetic and epigenetic factors which could be responsible for the different appearance and severity of disease phenotypes in AD.

Gene Polymorphism of Interleukin-4, Interleukin-4 Receptor and STAT6 in Children with Atopic Dermatitis in Taif, Saudi Arabia

AIM OF STUDY

This work was performed to evaluate the level of IL-4, and to clarify the role of IL-4 gene polymorphism at position cytosine -590-to-thyamine (C-590T), IL-4Rα gene polymorphism at position adenine +4679-to-guanine (A+4679G) [isoleucine-50-valine (I50V)] and STAT6 gene polymorphism at position guanine 2964-to-adenine (G2964A) in Saudi children with non-atopic dermatitis (non-AD) and atopic dermatitis (AD) to identify their role in the pathogenesis of these diseases.

SUBJECTS AND METHODS

This study included 150 children: 50 healthy children as controls, 50 with non-AD, and 50 with AD. They were subjected to full clinical examination, complete blood picture, skin prick test, and determination of serum interleukin-4 (IL-4) and total immunoglobulin-E (IgE) levels. Detection of interleukin-4 gene (C-590T), interleukin-4 receptor alpha gene (A+4679G) (I50V), and STAT6 gene (G2964A) polymorphisms were performed by PCR-based restriction fragment length polymorphism (PCR-RFLP).

RESULTS

There was a significant (P < 0.01) association between genotype and allele frequencies of IL-4Rα (A+4679G) (I50V) polymorphism in the AD group (but not non-AD group). Moreover, there was a significant association between genotype and allele frequencies of the STAT6 (G2946A) polymorphism in the non-AD (P < 0.05) and AD (P < 0.01) groups. On the other hand, there was no significant association between genotype and allele frequencies of the (C-590T) polymorphism in the non-AD group and AD group. There was a significant (P < 0.001) higher total IgE level in patients compared to the controls. Moreover, the mean values of total IgE were significantly different among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively, in all the studied groups. On the other hand, there was no significant difference of serum IL-4 levels among all the studied patients, or among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively.

CONCLUSION

IL-4Rα gene (I50V) and STAT6 gene (G2964) polymorphisms may play a role in development of eczema; however, the IL-4 gene polymorphism (C-590T) had no relationship with susceptibility to the disease among Saudi children.

Current knowledge on psoriasis and autoimmune diseases

Psoriasis is a prevalent, chronic inflammatory disease of the skin, mediated by crosstalk between epidermal keratinocytes, dermal vascular cells, and immunocytes such as antigen presenting cells (APCs) and T cells. Exclusive cellular “responsibility” for the induction and maintenance of psoriatic plaques has not been clearly defined. Increased proliferation of keratinocytes and endothelial cells in conjunction with APC/T cell/monocyte/macrophage inflammation leads to the distinct epidermal and vascular hyperplasia that is characteristic of lesional psoriatic skin. Despite the identification of numerous susceptibility loci, no single genetic determinant has been identified as responsible for the induction of psoriasis. Thus, numerous other triggers of disease, such as environmental, microbial and complex cellular interactions must also be considered as participants in the development of this multifactorial disease. Recent advances in therapeutics, especially systemic so-called “biologics” have provided new hope for identifying the critical cellular targets that drive psoriasis pathogenesis. Recent recognition of the numerous co-morbidities and other autoimmune disorders associated with psoriasis, including inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus suggest common signaling elements and cellular mediators may direct disease pathogenesis. In this review, we discuss common cellular pathways and participants that mediate psoriasis and other autoimmune disorders that share these cellular signaling pathways.

ΔNp63 regulates IL-33 and IL-31 signaling in atopic dermatitis

Atopic dermatitis (AD) is the most common inflammatory skin disease with no well-delineated cause or effective cure. Here we show that the p53 family member p63, specifically the ΔNp63, isoform has a key role in driving keratinocyte activation in AD. We find that overexpression of ΔNp63 in transgenic mouse epidermis results in a severe skin phenotype that shares many of the key clinical, histological and molecular features associated with human AD. This includes pruritus, epidermal hyperplasia, aberrant keratinocyte differentiation, enhanced expression of selected cytokines and chemokines and the infiltration of large numbers of inflammatory cells including type 2  T-helper cells – features that are highly representative of AD dermatopathology. We further demonstrate several of these mediators to be direct transcriptional targets of ΔNp63 in keratinocytes. Of particular significance are two p63 target genes, IL-31 and IL-33, both of which are key players in the signaling pathways implicated in AD. Importantly, we find these observations to be in good agreement with elevated levels of ΔNp63 in skin lesions of human patients with AD. Our studies reveal an important role for ΔNp63 in the pathogenesis of AD and offer new insights into its etiology and possible therapeutic targets.

Dietary deficiencies of unsaturated fatty acids and starch cause atopic dermatitis-like pruritus in hairless mice

Hairless mice fed with a special diet (named HR-AD) show atopic dermatitis (AD)-like pruritic skin inflammation that is almost completely resolved with the supplementation of an unsaturated fatty acid (UFA), the linoleic acid (LA). This suggests that the dietary deficiency of LA is the key cause of this dermatitis. However, because there is no appropriate control diet for HR-AD, the involvement of other dietary ingredients cannot be ruled out. Furthermore, it has not yet been tested whether only UFA deficiency can cause such AD-like pruritus. In this study, using semi-purified custom diets, we attempted to reproduce this syndrome. Four-week-old hairless mice were maintained on a widely used standard diet American Institute of Nutrition-76A (AIN-76A), its modifications, or HR-AD. Several modifications of fat and carbohydrate components revealed that dietary deficiency of both UFAs and cornstarch was required to induce severe skin barrier dysfunction as typically occurred in HR-AD-fed mice. An UFA- and cornstarch-deficient diet caused severe AD-like pruritus comparable to HR-AD, despite weak Th2 immune responses and absence of immunoglobulin E production. On the other hand, a diet lacking UFAs but containing cornstarch significantly alleviated the development of pruritic dermatitis. Furthermore, the supplementation of wheat starch similarly improved skin barrier function. In conclusion, this study showed that a lack of certain starches might also be the cause of diet-induced AD. Our findings could help to reproduce the diet-induced AD itch model and also provide evidence that certain starches can have protective and ameliorative effects on AD-like pruritus.

Early pediatric atopic dermatitis shows only a cutaneous lymphocyte antigen (CLA)(+) TH2/TH1 cell imbalance, whereas adults acquire CLA(+) TH22/TC22 cell subsets

BACKGROUND

Identifying differences and similarities between cutaneous lymphocyte antigen (CLA)(+) polarized T-cell subsets in children versus adults with atopic dermatitis (AD) is critical for directing new treatments toward children.

OBJECTIVE

We sought to compare activation markers and frequencies of skin-homing (CLA(+)) versus systemic (CLA(-)) "polar" CD4 and CD8 T-cell subsets in patients with early pediatric AD, adults with AD, and control subjects.

METHODS

Flow cytometry was used to measure CD69/inducible costimulator/HLA-DR frequency in memory cell subsets, as well as IFN-γ, IL-13, IL-9, IL-17, and IL-22 cytokines, defining TH1/cytotoxic T (TC) 1, TH2/TC2, TH9/TC9, TH17/TC17, and TH22/TC22 populations in CD4 and CD8 cells, respectively. We compared peripheral blood from 19 children less than 5 years old and 42 adults with well-characterized moderate-to-severe AD, as well as age-matched control subjects (17 children and 25 adults).

RESULTS

Selective inducible costimulator activation (P < .001) was seen in children. CLA(+) TH2 T cells were markedly expanded in both children and adults with AD compared with those in control subjects, but decreases in CLA(+) TH1 T-cell numbers were greater in children with AD (17% vs 7.4%, P = .007). Unlike in adults, no imbalances were detected in CLA(-) T cells from pediatric patients with AD nor were there altered frequencies of TH22 T cells within the CLA(+) or CLA(-) compartments. Adults with AD had increased frequencies of IL-22-producing CD4 and CD8 T cells within the skin-homing population, compared with controls (9.5% vs 4.5% and 8.6% vs 2.4%, respectively; P < .001), as well as increased HLA-DR activation (P < .01).

CONCLUSIONS

These data suggest that TH2 activation within skin-homing T cells might drive AD in children and that reduced counterregulation by TH1 T cells might contribute to excess TH2 activation. TH22 "spreading" of AD is not seen in young children and might be influenced by immune development, disease chronicity, or recurrent skin infections.

T-helper 22 cells as a new player in chronic inflammatory skin disorders

T-helper 22 (Th22) cell is a new subset of CD4+ T cells that secrets interleukin (IL)-22 but not IL-17 or interferon-γ. Th22 is distinct from Th17 and other known CD4+ T-cell subsets with distinguished gene expression and function. Th22 subsets have chemokine receptors CCR6+ CCR4+ CCR10+ phenotype and aryl hydrocarbon receptor as the key transcription factor. This T-helper subset, by producing cytokines such as IL-22, IL-13, and tumor necrosis factor-α, is implicated in the pathogenesis of inflammatory skin disorder. This review discusses the role of Th22 and its cytokine IL-22 in the immunopathogenesis of inflammatory skin disorders such as psoriasis and atopic dermatitis.

Personalized Immunomodulatory Therapy for Atopic Dermatitis: An Allergist's View

The current standard medical therapy for atopic dermatitis (AD) mainly focuses on symptomatic relief by controlling skin inflammation with topical corticosteroids and/or topical calcineurin inhibitors. However, the clinical efficacy of pharmacological therapy is often disappointing to both patients and physicians. The terminology of AD contains a historical meaning of eczematous dermatitis caused by hypersensitivity reaction to environmental inhalant or food allergen. Complex interrelationships among genetic abnormalities, environmental triggers, skin barrier defects, and immune dysfunction resulting in a vicious domino-circle seem to be involved in the development and maintenance of AD. In the viewpoint of AD as an allergic disease, complete avoidance of clinically relevant allergen or induction of specific immune tolerance through administrations of allergen (allergen immunotherapy) can provide clinical remission by breaking the vicious domino-circle maintaining a chronic disease state. In recent clinical studies, monoclonal antibodies including the anti-interleukin-4 receptor antibody and anti-B cell antibody induced significant clinical improvements in patients with AD. The detailed characteristics of immune dysfunction are heterogeneous among patients with AD. Therefore, a personalized combination of immunomodulatory therapies to reduce hypersensitivity (allergen immunotherapy) and correct immune dysfunction (monoclonal antibody therapy) could be a reasonable therapeutic approach for patients with AD. Future immunomodulatory therapies for AD should be developed to achieve long-term treatment-free clinical remission by induction of immune tolerance.

Regulation of Dendritic Cell Function in Inflammation

Dendritic cells (DC) are professional antigen presenting cells and link the innate and adaptive immune system. During steady state immune surveillance in skin, DC act as sentinels against commensals and invading pathogens. Under pathological skin conditions, inflammatory cytokines, secreted by surrounding keratinocytes, dermal fibroblasts, and immune cells, influence the activation and maturation of different DC populations including Langerhans cells (LC) and dermal DC. In this review we address critical differences in human DC subtypes during inflammatory settings compared to steady state. We also highlight the functional characteristics of human DC subsets in inflammatory skin environments and skin diseases including psoriasis and atopic dermatitis. Understanding the complex immunoregulatory role of distinct DC subsets in inflamed human skin will be a key element in developing novel strategies in anti-inflammatory therapy.

Inhibitory effect of 5,6-dihydroergosteol-glucoside on atopic dermatitis-like skin lesions via suppression of NF-κB and STAT activation

BACKGROUND

Atopic dermatitis (AD) is a Th2-type disease. Keratinocytes, a major type in the skin, produce Th2 chemokines such as thymus and activation-regulated chemokine (TARC)/CCL17 and macrophage-derived chemokine (MDC)/CCL22, which play pivotal roles in the development of Th2-dominant inflammatory skin diseases. Recently, it was reported that 5,6-dihydroergosterol-glucoside (DHE-Glc) was synthesized and exhibited strong anti-inflammatory activity.

OBJECTIVE

We aimed to investigate the effects of DHE-Glc, a synthetic molecule derived from ergosterol, on AD-like skin lesions induced by 2,4-dinitrochlorobenzene (DNCB) in mice and to elucidate the effects of DHE-Glc on TNF-α/IFN-γ-induced production of CCL17 and CCL22 in human keratinocytes (HaCaTs) and DNCB induced skin inflammation mice model.

METHOD

Mice were sensitized and challenged on the skin of their backs with DNCB. At 30-60 days after sensitization, mice were treated with cutaneous administration of DHE-Glc by skin smear. HaCaT cells were used to evaluate the effects of DHE-Glc on production of CCL17 and CCL22 and investigate mechanisms of action by RT-PCR, ELISA, Western blot, and reporter assays.

RESULT

Topical administration of DHE-Glc attenuated AD-like skin inflammatory symptoms. DHE-Glc decreased infiltration of epidermal eosinophils and mast cells, and reduced levels of IgE, histamine, and mRNA expression and protein levels of CCL17/CCL22 in the plasma of DNCB-treated animals. In addition, DHE-Glc suppressed TNF-α/IFN-γ-induced expression of the Th2 chemokines CCL17 and CCL22 by inhibiting NF-κB and STAT activation in TNF-α/IFN-γ-induced HaCaT cells.

CONCLUSION

DHE-Glc improved AD-like skin inflammatory symptoms on the backs of DNCB-induced mice, partly by suppressing production of Th2 chemokines, CCL17 and CCL22 in inflamed skin. Therefore, DHE-Glc is a potential therapeutic agent for skin inflammatory diseases such as AD.

Factors associated with different results of allergy tests in children with dust mite-induced atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a public health problem, with an increasing prevalence worldwide. AD is a chronic inflammatory disease characterised by skin lesions and severe itching. Immunologically, AD has two forms, IgE-mediated and cell-mediated, but it may also be idiopathic. In the pathogenesis of AD, the gene mutations for filaggrin, a filament-aggregating protein present in the epidermis, are of pivotal importance, but other genetic factors are also operating, including those linked to family atopy.

METHODS

We evaluated the role of family atopy, and of the results of the atopy patch test (APT) in parents, in children with mite-induced AD. 64 children, 38 males and 26 females, mean age 4.97 years, were included for the diagnosis of AD and underwent APT and skin prick test (SPT) with dust mite extracts, with evaluation of atopy and result of APT also in parents.

RESULTS

A positive family history of atopy was shown for children with positivity to both APT and SPT compared to those with negative or only one positive result to APT or SPT (p=0.08). Significant associations were found concerning APT results in children and parents. In particular, children of a positive-APT parent had an 18-fold higher risk of APT-positivity in comparison with children of negative-APT parents, while the risk was 6.6-fold higher if APT was positive in father.

CONCLUSION

Family atopy and a positive APT in fathers are risk factors to develop cell-mediated AD, as assessed by the APT, in children.

Immune Pathways in Atopic Dermatitis, and Definition of Biomarkers through Broad and Targeted Therapeutics

Atopic dermatitis (AD) is the most common inflammatory skin disease. Recent research findings have provided an insight into the complex pathogenic mechanisms involved in this disease. Despite a rising prevalence, effective and safe therapeutics for patients with moderate-to-severe AD are still lacking. Biomarkers of lesional, nonlesional skin, and blood have been developed for baseline as well as after treatment with broad and specific treatments (i.e., cyclosporine A and dupilumab). These biomarkers will help with the development of novel targeted therapeutics and assessment of disease reversal, with the promise of a more personalized treatment approach. Since AD involves more than one subtype (i.e., intrinsic/extrinsic, pediatric/adult, etc.), these molecular fingerprints needs to be validated in all subpopulations with AD.

Gross cystic disease fluid protein 15 in stratum corneum is a potential marker of decreased eccrine sweating for atopic dermatitis

It is well known that eccrine sweating is attenuated in patients with atopic dermatitis (AD). We have reported by using proteome analysis that gross cystic disease fluid protein 15 (GCDFP15), a substance secreted from eccrine sweat glands, is decreased in tape-stripped stratum corneum (SC) samples from AD patients. The aim of this study was to evaluate GCDFP15 production by eccrine glands with SC samples and to assess sweating in AD. SC samples were obtained from 51 healthy control (HC) and 51 AD individuals. Sweat samples were from 18 HC and 12 AD subjects. GCDFP15 was quantified by ELISA. By immunohistochemistry, the expression of GCDFP15 in eccrine glands was examined in normal and AD skin specimens. To identify GCDFP15-producing cells, double immunofluorescence staining for GCDFP15 and S100 protein was performed in frozen sections. To address the mechanism underlying the decreased eccrine sweating in AD patients, we examined the expression of cholinergic receptor M3 (CHRM3), a receptor for acetylcholine-induced sweating, in eccrine sweat glands. The amounts of GCDFP15 in the SC extracts were significantly lower in AD than HC (P < 0.0001). The sweat samples from AD patients also had lower levels of GCDFP15 concentration (P < 0.05). Immunohistochemistry showed positive GCDFP15 staining in the eccrine gland secretory cells and the ductal and acrosyringial lumen in normal skin, but AD lacked clear staining. Immunofluorescence staining revealed that GCDFP15 was co-expressed with S100 protein, suggesting that the clear cell of eccrine glands produces GCDFP15. Finally, we found that the expression of CHRM3 was depressed in AD, suggesting contribution to the low sweating. The SC of AD patients contains a low amount of GCDFP15 due to both low sweating and low GCDFP15 concentration in the sweat. GCDFP15 in SC is a potential marker for dysregulated sweating in AD.

Toll-like receptor 2 agonist Pam3CSK4 up-regulates FcεRI receptor expression on monocytes from patients with severe extrinsic atopic dermatitis

BACKGROUND

Both microbial antigens and allergens are important factors that can trigger atopic dermatitis (AD). Monocytes from patients with AD have been found to express increased and sustained levels of high-affinity IgE receptor (FcεRI) and Toll-like receptor 2 (TLR2). We hypothesized that putative interactions exist between TLR2 and FcεRI on monocytes in the pathogenesis of AD.

OBJECTIVE

This study aimed to understand whether activation of TLR2 by Pam3CSK4 would influence the expression of FcεRI, and whether mitogen-activated protein kinase (MAPK) signalling pathways were involved in such regulation.

METHODS

Peripheral blood monocytes from patients with severe extrinsic AD or healthy control patients were treated with the TLR2 agonist Pam3CSK4. The expression of FcεRI, intracellular TNF-α and MAPK family members were analysed by real-time quantitative PCR, flow cytometry and western blotting.

RESULTS

Monocytes from patients with severe extrinsic AD expressed higher levels of surface FcεRIα than were found in monocytes from healthy controls. Stimulation of human monocytes from patients with Pam3CSK4, but not lipopolysaccharide (LPS), resulted in the up-regulation of surface FcεRI expression by inducing p38 phosphorylation. Pretreatment with a specific inhibitor of p38 kinase inhibited the Pam3CSK4-induced up-regulation of FcεRIα, suggesting the involvement of the p38 pathway in the regulation of this process.

CONCLUSION

Our findings indicated interactions between TLR2 and FcεRI occurred via the activation of p38 in patients with severe extrinsic AD, which might indicate insights into understanding the mechanisms of how bacterial infection can exacerbate the clinical features of AD.

Contact sensitivity in patients with recalcitrant atopic dermatitis

Patients with atopic dermatitis are usually responsive to conventional treatment such as topical steroids; however, they are sometimes refractory to the treatment. The influence of contact sensitivities on the course of patients with recalcitrant atopic dermatitis is not known. The aim of this study was to investigate whether contact sensitivities affect the course of patients with recalcitrant atopic dermatitis. We evaluated 45 patients with atopic dermatitis who had failed conventional therapy. Patch testing was performed with the Japanese standard series, metal series and/or suspected items. A total of 15 patients had a positive patch test reaction to at least one allergen. The most common allergens were nickel, topical drugs and rubber accelerators. Avoidance of products or food containing allergic substances greatly or partially improved skin symptoms in nine patients. These results suggest that contact allergens and metals may be critical factors causing eczematous lesions in patients with recalcitrant atopic dermatitis.

IL-9 induces IL-8 production via STIM1 activation and ERK phosphorylation in epidermal keratinocytes: A plausible mechanism of IL-9R in atopic dermatitis

BACKGROUND

IL-9 and its receptor play important roles in the pathogenesis of asthma. Its role in atopic dermatitis (AD) was examined in just a few studies, including nucleotide polymorphisms, increased transcriptional levels of IL-9 and IL-9R in diseased skin, and an association of blood IL-9 levels with clinical severity.

OBJECTIVE

Little was known about the pathophysiological regulation of IL-9/IL-9R in AD skin. We asked whether IL-9R was expressed in epidermal keratinocytes; if so, what the functional outcome, cytokine production, and signaling pathway of IL-9/IL-9R in keratinocytes are.

METHODS

We measured and compared the expression of IL-9R in skin from AD patients and controls by immunofluorescence. We also performed in vitro studies on the IL-9-treated primary keratinocytes, including flow cytometry for IL-9R expressions, Western blotting for mTOR, S6K, ERK, p38, and STAT3 activations, ELISA for cytokine levels, and immunofluorescence for STIM1.

RESULTS

We found that IL-9R was indeed expressed in keratinocytes but not in fibroblasts. Its expression in keratinocytes was enhanced by IL-4 but not by TGF-beta1. IL-9 induced a moderate production of IL-8 but not CXCL16, CCL22, TSLP, nor IL-33. IL-9 induced formation of STIM1-puncta. IL-9 induced ERK phosphorylation both dose- and time-dependently, but not mTOR, S6K, p38, or STAT3. Pretreatment with U0126 (ERK inhibitor) but not rapamycin (mTOR inhibitor) abrogated the IL-9-mediated IL-8 production. Blockage of STIM1 with BTP2 or SKF96265 abrogated ERK phosphorylation and IL-8 production induced by IL-9.

CONCLUSION

This study represents the first to show the regulation of the IL-9-STIM1-ERK-IL-8 axis in keratinocyte, and how the axis might play an important role in the pathophysiology of AD.

Danggui buxue tang inhibits 2,4-dinitrochlorobenzene: induced atopic dermatitis in mice

Danggui Buxue Tang (DBT) is a herbal decoction that has been used in Chinese medicine to enhance qi and blood circulation. Previously, we found that DBT can suppress allergy-related asthma in mice, leading us to hypothesize that DBT might ameliorate allergy disease. In this study, we evaluated whether DBT can attenuate atopic dermatitis (AD) symptoms and have an anti-inflammatory effect on AD-like mice. The dorsal skin of female mice was shaved and sensitized cutaneously (skin smear) with 1-chloro-2,4-dinitrobenzene. Mice were then given various doses of DBT from days 14 to 29 cutaneously. DBT treatment suppressed ear swelling and skin inflammation and decreased mast cell and eosinophil infiltration into skin and ear tissue. DBT also inhibited levels of IgE and Th2-associated cytokine levels in serum. These results demonstrate that cutaneous administration of DBT reduced the development of AD-like skin lesions in mice.

IgE-mediated sensitization to malassezia in atopic dermatitis: more common in male patients and in head and neck type

BACKGROUND

Atopic dermatitis (AD) is a common chronic inflammatory skin disease. Malassezia, the predominant skin microbiota fungus, is considered to exacerbate AD, especially in a subset of patients with head and neck type AD (HNAD). In the present study, the relationship between AD and sensitization to Malassezia antigens was investigated.

METHODS

We assessed 173 patients with AD. The severity of eczema was determined with Eczema Area and Severity Index (EASI); the type of AD, namely, head and neck type, was reported as well. The total serum IgE and specific IgE to Malassezia were determined and correlated with clinical picture of AD, sex, age, and the EASI.

RESULTS

Total IgE was elevated in 77.7% of patients. Specific IgE to Malassezia was positive (≥0.35 kU/L) in 49.1% of patients. Men were significantly more often sensitized to Malassezia antigen (58% of men vs 42% of women; P value, 0.04). Concurrently, 58% of patients with HNAD versus 42% non-HNAD patients had higher levels of specific IgE to Malassezia, this difference being nearly significant (P value, 0.06). Patients with atopy were also more frequently sensitized to Malassezia. No significant relationship between EASI and the level of total IgE or specific IgE to Malassezia was observed.

CONCLUSIONS

In our population, IgE-mediated sensitization was found in up to 49% of all patients with AD, most common in men and in head and neck type.

Antihistamines and itch

Histamine is one of the best-characterized pruritogens in humans. It is known to play a role in pruritus associated with urticaria as well as ocular and nasal allergic reactions. Histamine mediates its effect via four receptors. Antihistamines that block the activation of the histamine H₁receptor, H₁R, have been shown to be effective therapeutics for the treatment of pruritus associated with urticaria, allergic rhinitis, and allergic conjunctivitis. However, their efficacy in other pruritic diseases such as atopic dermatitis and psoriasis is limited. The other histamine receptors may also play a role in pruritus, with the exception of the histamine H₂receptor, H₂R. Preclinical evidence indicates that local antagonism of the histamine H₃receptor, H₃R, can induce scratching perhaps via blocking inhibitory neuronal signals. The histamine H₄receptor, H₄R, has received a significant amount of attention as to its role in mediating pruritic signals. Indeed, it has now been shown that a selective H₄R antagonist can inhibit histamine-induced itch in humans. This clinical result, in conjunction with efficacy in various preclinical pruritus models, points to the therapeutic potential of H₄R antagonists for the treatment of pruritus not controlled by antihistamines that target the H₁R.

Therapeutic strategies in extrinsic atopic dermatitis: focus on inhibition of IL-4 as a new pharmacological approach

INTRODUCTION

Recent data about atopic dermatitis (AD) pathogenesis postulate that T cells and their related cytokines and chemokines are primarily responsible for the inflammatory responses.

AREAS COVERED

AD, the primary complex disease associated with filaggrin deficiency, is characterized by cutaneous inflammation driven by type 2 helper T (TH2) cells. TH2-related molecules, such as IL-4, IL-13, dominate the immune infiltrate. Experimental evidences suggest that these cytokines may be considered attractive therapeutic targets in AD, particularly in extrinsic AD with IgE overproduction. Recently, a fully human monoclonal antibody directed against the IL-4 receptor α subunit blocking IL-4 and IL-13 signaling has been evaluated in Phase I and Phase II clinical trials in patients with moderate-to-severe AD with significant improvement in disease severity. Phase III trials are ongoing.

EXPERT OPINION

Treatment of AD represents a therapeutic challenge. TH2 cytokine-targeted therapies represent promising treatment options that could improve the therapeutic armamentarium for AD. These therapies are likely to become future therapeutic options in AD, particularly in the extrinsic AD.

Molecular biology of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific genetic and immunological mechanisms. The rapid development of new techniques in molecular biology had ushered in new discoveries on the role of cytokines, chemokines, and immune cells in the pathogenesis of AD. New polymorphisms of AD are continually being reported in different populations. The physical and immunological barrier of normal intact skin is an important part of the innate immune system that protects the host against microbials and allergens that are associated with AD. Defects in the filaggrin gene FLG may play a role in facilitating exposure to allergens and microbial pathogens, which may induce Th2 polarization. Meanwhile, Th22 cells also play roles in skin barrier impairment through IL-22, and AD is often considered to be a Th2/Th22-dominant allergic disease. Mast cells and eosinophils are also involved in the inflammation via Th2 cytokines. Release of pruritogenic substances by mast cells induces scratching that further disrupts the skin barrier. Th1 and Th17 cells are mainly involved in chronic phase of AD. Keratinocytes also produce proinflammatory cytokines such as thymic stromal lymphopoietin (TSLP), which can further affect Th cells balance. The immunological characteristics of AD may differ for various endotypes and phenotypes. Due to the heterogeneity of the disease, and the redundancies of these mechanisms, our knowledge of the pathophysiology of the disease is still incomplete, which is reflected by the absence of a cure for the disease.

Dupilumab treatment in adults with moderate-to-severe atopic dermatitis

BACKGROUND

Dupilumab, a fully human monoclonal antibody that blocks interleukin-4 and interleukin-13, has shown efficacy in patients with asthma and elevated eosinophil levels. The blockade by dupilumab of these key drivers of type 2 helper T-cell (Th2)-mediated inflammation could help in the treatment of related diseases, including atopic dermatitis.

METHODS

We performed randomized, double-blind, placebo-controlled trials involving adults who had moderate-to-severe atopic dermatitis despite treatment with topical glucocorticoids and calcineurin inhibitors. Dupilumab was evaluated as monotherapy in two 4-week trials and in one 12-week trial and in combination with topical glucocorticoids in another 4-week study. End points included the Eczema Area and Severity Index (EASI) score, the investigator's global assessment score, pruritus, safety assessments, serum biomarker levels, and disease transcriptome.

RESULTS

In the 4-week monotherapy studies, dupilumab resulted in rapid and dose-dependent improvements in clinical indexes, biomarker levels, and the transcriptome. The results of the 12-week study of dupilumab monotherapy reproduced and extended the 4-week findings: 85% of patients in the dupilumab group, as compared with 35% of those in the placebo group, had a 50% reduction in the EASI score (EASI-50, with higher scores in the EASI indicating greater severity of eczema) (P<0.001); 40% of patients in the dupilumab group, as compared with 7% in the placebo group, had a score of 0 to 1 (indicating clearing or near-clearing of skin lesions) on the investigator's global assessment (P<0.001); and pruritus scores decreased (indicating a reduction in itch) by 55.7% in the dupilumab group versus 15.1% in the placebo group (P<0.001). In the combination study, 100% of the patients in the dupilumab group, as compared with 50% of those who received topical glucocorticoids with placebo injection, met the criterion for EASI-50 (P=0.002), despite the fact that patients who received dupilumab plus glucocorticoids used less than half the amount of topical glucocorticoids used by those who received placebo plus the topical medication (P=0.16). Adverse events, such as skin infection, occurred more frequently with placebo; nasopharyngitis and headache were the most frequent adverse events with dupilumab.

CONCLUSIONS

Patients treated with dupilumab had marked and rapid improvement in all the evaluated measures of atopic dermatitis disease activity. Side-effect profiles were not dose-limiting. (Funded by Regeneron Pharmaceuticals and Sanofi; ClinicalTrials.gov numbers, NCT01259323, NCT01385657, NCT01639040, and NCT01548404.).

Low prevalence of IgA anti-transglutaminase 1, 2, and 3 autoantibodies in children with atopic dermatitis

Background

Atopic dermatitis (AD) is a multifactorial chronic inflammatory skin disease presenting with a relapsing clinical pattern similar to chronic autoimmune disease. Several human transglutaminases have been defined and keratinocyte transglutaminase (TG1) and epidermal transglutaminase (TG3) expressed in the epidermis are associated with epidermal barrier dysfunction. Since impairments to the epidermal barrier represent an important factor in AD, we hypothesized that IgA autoantibodies specific for TG1 (IgA-anti-TG1) and TG3 (IgA-anti-TG3) may affect AD development during childhood.

Methods

Active AD patients (n = 304), 28 patients with biopsy-confirmed coeliac disease (CD), 5 patients with active AD and CD, and 55 control patients without CD and skin diseases were enrolled into the study. IgA-anti-TG1 and IgA-anti-TG3 reactivity was determined using an enzyme-linked immunosorbent assay. IgA-anti-TG2 were defined using a fluoroenzyme immunoassay.

Results

IgA-anti-TG1 antibodies were found in 2% and IgA-anti-TG3 antibodies in 3% of patients with active AD. Two out of the 5 patients with AD and concomitant CD had IgA-anti-TG1 and IgA-anti-TG2 antibodies. In CD patients, 36% of individuals presented with elevated IgA-anti-TG1 antibodies and 18% presented with elevated IgA-anti-TG3 antibodies and all CD patients presented with IgA-anti-TG2 antibodies (significantly different from AD patients and controls, p < 0.05). In CD patients, IgA-anti-TG1 and/or IgA-anti-TG3 seropositivity tended to appear concurrently, whereas only one patient with AD had both types of autoantibodies.

Conclusions

IgA-anti-TG1 and IgA-anti-TG3 seropositivity was rare in active AD but frequent in CD patients. The level of circulating antibodies related to skin lesions could be studied by determining the levels of IgA-anti-TG1 and IgA-anti-TG3 in skin biopsies of AD patients.

Antinuclear antibodies in atopic dermatitis: a cross-sectional study on 346 children

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease that can be classified into an extrinsic or intrinsic type. A high percentage of patients, especially adults with the extrinsic type of AD, have been reported to show antibodies to antinuclear proteins (ANA). We aimed to study the prevalence of ANA in children with AD and to evaluate clinical differences between patients with ANA-positive and ANA-negative AD.

METHODS

A total 346 serum samples from children with active AD (mean age 5.8 years) and 117 hospital controls without known skin, inflammatory, or immune-mediated disease (mean age 7.9 years) were tested for IgG ANA with indirect immunofluorescence on HEp-2 cells, total serum IgE levels, and IgE type antibodies to food allergen panels.

RESULTS

In total, 47 patients with AD (13.6%) and 15 subjects in the control group (12.8%) were ANA positive at screening dilution 1:10 (P > 0.05). In patients with AD, ANA was found already at the age of 2 years, significantly more often in females (P < 0.005) and at slightly higher titers (up to 1:160). No differences were found in ANA positivity regarding the severity of AD or sensitization to food allergens.

CONCLUSION

No significant differences were observed between AD and the control group, or between different subtypes of AD in ANA prevalence. In both groups, ANA frequency increased with age, but in patients with AD, ANA had a tendency to appear earlier. Therefore, active AD during the early years of life could dispose selected patients towards earlier development of systemic autoreactivity and stress the need for regular follow-up of patients with ANA-positive AD.

Clinical pearls from atopic dermatitis and its infectious complications

Atopic dermatitis (AD) is clinically very heterogeneous and these differences can cause confusion. Differential diagnosis is also complicated by co-infections, particularly in infancy and early childhood. This paper describes the stages and differential diagnosis during the various stages of childhood. The authors also provide advice on how to distinguish between AD and other disorders together with guidance on tackling common issues with treatment such as steroid phobia.

Possible new therapeutic strategy to regulate atopic dermatitis through upregulating filaggrin expression

BACKGROUND

Nonsense mutations in filaggrin (FLG) represent a significant genetic factor in the cause of atopic dermatitis (AD).

OBJECTIVE

It is of great importance to find drug candidates that upregulate FLG expression and to determine whether increased FLG expression controls the development of AD.

METHODS

We screened a library of bioactives by using an FLG reporter assay to find candidates that promoted FLG mRNA expression using a human immortalized keratinocyte cell line (HaCaT). We studied the effect of the compound on keratinocytes using the human skin equivalent model. We examined the effect of the compound on AD-like skin inflammation in NC/Nga mice.

RESULTS

JTC801 promoted FLG mRNA and protein expression in both HaCaT and normal human epidermal keratinocytes. Intriguingly, JTC801 promoted the mRNA and protein expression levels of FLG but not the mRNA levels of other makers for keratinocyte differentiation, including loricrin, keratin 10, and transglutaminase 1, in a human skin equivalent model. In addition, oral administration of JTC801 promoted the protein level of Flg and suppressed the development of AD-like skin inflammation in NC/Nga mice.

CONCLUSION

This is the first observation that the compound, which increased FLG expression in human and murine keratinocytes, attenuated the development of AD-like skin inflammation in mice. Our findings provide evidence that modulation of FLG expression can be a novel therapeutic target for AD.

Chemokine-like factor 1 (CLFK1) is over-expressed in patients with atopic dermatitis

Background: Human chemokine-like factor 1 (CKLF1), a recently discovered chemokine, has a broad spectrum of biological functions in immune-mediated diseases. It is highly expressed on Th2 lymphocytes and is a functional ligand for human CCR4. CKLF1 has a major role in the recruitment and activation of leucocytes, which plays an important role in the pathogenesis of allergic diseases. The present study was designed to determine the expression of CKLF1 in skin and serum in patients with atopic dermatitis (AD).

Methods: The CKLF1 protein expression in skin lesion was analyzed by immunohistochemistry and ELISA. The mRNA expression of CKLF1 in skin lesion was detected by Real-time PCR. The serum levels of CKLF1, IgE, eotaxin, IL-4, IL-5, and IL-13 were measured by ELISA.

Results: Histopathological changes in the skin of AD patients showed local inflammation with epidermal thickening and significant inflammatory cellular infiltration. Immunohistochemistry results demonstrated that CKLF1-staining positive cells were located in the epidermal and dermis, and that the CKLF1 expression in AD patients was significantly higher than that in normal control. The CKLF1 mRNA expression in AD patients was significantly higher than that in healthy controls. Serum CKLF1 and IgE levels were significantly increased in AD patients, as were the serum levels of IL-4, IL-5, IL-13 and eotaxin.

Conclusions: Both CKLF1 protien and mRNA levels are overexpressed in the skin lesion of AD patients, along with an increase in serum CKLF1 level, indicating that CKLF1 may play an important role in the development of atopic dermatitis.

High frequencies of positive nickel/cobalt patch tests and high sweat nickel concentration in patients with intrinsic atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is classified into extrinsic AD with high serum IgE levels and impaired barrier, and intrinsic AD with low serum IgE levels and unimpaired barrier. Intrinsic AD has a lower frequency of FLG mutations and a higher frequency of circulating Th1 cells, implying that non-protein antigens, represented by metals, may be an exacerbation factor in intrinsic AD.

OBJECTIVE

To investigate metal allergy in intrinsic AD.

METHODS

Enrolled in this study were 86 Japanese AD patients seen in three university hospitals, consisting of 55 extrinsic and 31 intrinsic AD patients. Patch testing was performed, focusing on nickel, cobalt, and chrome, in parallel with other 14 metals. FLG mutations were analyzed in 49 patients (extrinsic, 29; intrinsic, 20). In 17 patients (extrinsic, 12; intrinsic, 5), sweat was collected from the forearms by exercise, and the concentration of nickel was fluorometrically measured.

RESULTS

Nickel, cobalt, and chrome were the major positive metals. Intrinsic AD showed significantly higher percentages of positive reactions than extrinsic AD to nickel (intrinsic 41.9% vs extrinsic 16.4%, P=0.019) and cobalt (38.7% vs 10.9%, P=0.005). There was no significant difference between FLG mutation-bearing and non-bearing patients. The concentration of nickel was higher in the sweat of intrinsic AD than extrinsic AD patients (333.8 vs 89.4ng/g, P=0.0005) and inversely correlated with serum IgE levels.

CONCLUSIONS

Nickel and cobalt allergy may be involved in intrinsic AD. Given that the metals are excreted through sweat, intrinsic AD might be exaggerated by highly metal-containing sweat.

Effect of dehydroepiandrosterone on atopic dermatitis-like skin lesions induced by 1-chloro-2,4-dinitrobenzene in mouse

BACKGROUND

Th2 cells are overexpressed in the skin and serum of atopic dermatitis (AD) patients. Previously, we found that dehydroepiandrosterone (DHEA) decreased eosinophil infiltration in asthmatic mice through the suppression of Th2-associated cytokines. Therefore, we hypothesized that DHEA might improve the symptoms of AD syndrome.

OBJECTIVE

In this study, we evaluated the symptom improvement and anti-inflammatory response that result from the modulation of immunity by DHEA modulated in AD-like mice.

METHODS

Female BALB/c mice were sensitized and challenged with 1-chloro-2,4-dinitrobenzene. On days 14-29 after sensitization, mice were treated with cutaneous (skin smear) or oral administration of DHEA. In addition, human keratinocyte (HaCat) cells were used to evaluate the effect of DHEA on the in vitro production of proinflammatory cytokines and chemokines.

RESULTS

Both cutaneous and oral DHEA were able to decrease ear swelling and skin inflammation in AD-like mice. DHEA also attenuated eosinophil and mast cell infiltration into ear and skin tissue. Additionally, Th2-associated cytokines were inhibited in splenocyte culture, and suppressed the levels of IgE and interleukin 4 in serum. Oral and cutaneous administration of DHEA reduced the inflammatory response, as evidenced by AD-like skin lesions, in a similar manner. DHEA significantly reduced inflammatory cytokines and chemokines through the nuclear factor-κB and mitogen-activated protein kinases pathways in tumor necrosis factor-α activated HaCat cells.

CONCLUSION

DHEA ameliorates AD-like mouse skin inflammation and reduces eosinophil and mast cell infiltration by reducing the production of Th2-associated cytokines and chemokines.

Intrinsic atopic dermatitis shows similar TH2 and higher TH17 immune activation compared with extrinsic atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is classified as extrinsic and intrinsic, representing approximately 80% and 20% of patients with the disease, respectively. Although sharing a similar clinical phenotype, only extrinsic AD is characterized by high serum IgE levels. Because most patients with AD exhibit high IgE levels, an "allergic"/IgE-mediated disease pathogenesis was hypothesized. However, current models associate AD with T-cell activation, particularly TH2/TH22 polarization, and epidermal barrier defects.

OBJECTIVE

We sought to define whether both variants share a common pathogenesis.

METHODS

We stratified 51 patients with severe AD into extrinsic AD (n = 42) and intrinsic AD (n = 9) groups (with similar mean disease activity/SCORAD scores) and analyzed the molecular and cellular skin pathology of lesional and nonlesional intrinsic AD and extrinsic AD by using gene expression (real-time PCR) and immunohistochemistry.

RESULTS

A significant correlation between IgE levels and SCORAD scores (r = 0.76, P < 10(-5)) was found only in patients with extrinsic AD. Marked infiltrates of T cells and dendritic cells and corresponding epidermal alterations (keratin 16, Mki67, and S100A7/A8/A9) defined lesional skin of patients with both variants. However, higher activation of all inflammatory axes (including TH2) was detected in patients with intrinsic AD, particularly TH17 and TH22 cytokines. Positive correlations between TH17-related molecules and SCORAD scores were only found in patients with intrinsic AD, whereas only patients with extrinsic AD showed positive correlations between SCORAD scores and TH2 cytokine (IL-4 and IL-5) levels and negative correlations with differentiation products (loricrin and periplakin).

CONCLUSIONS

Although differences in TH17 and TH22 activation exist between patients with intrinsic AD and those with extrinsic AD, we identified common disease-defining features of T-cell activation, production of polarized cytokines, and keratinocyte responses to immune products. Our data indicate that a TH2 bias is not the sole cause of high IgE levels in patients with extrinsic AD, with important implications for similar therapeutic interventions.

Arazyme inhibits cytokine expression and upregulates skin barrier protein expression

In the present study, the inhibitory effect of arazyme on allergic inflammation was investigated by evaluating the alteration of cytokine production and expression of skin barrier proteins in immune and HaCaT human keratinocyte cells. THP‑1 human monocytic and EoL‑1 human eosinophilic cells were treated with Dermatophagoides pteronissinus extract (DpE). Monocyte chemotactic protein‑1 (MCP‑1)/CCL2, interleukin (IL)‑6 and IL‑8 increased following DpE treatment and arazyme significantly blocked the increase of MCP‑1, IL‑6 and IL‑8 expression in cell types. Secretion of MCP‑1, IL‑6 and IL‑8 induced by lipopolysaccharide in THP‑1 cells was also inhibited by arazyme treatment. Arazyme inhibited the secretion of IL‑6 and IL‑8 due to phorbol 12‑myristate 13‑acetate and calcium ionophores in human mast cells. Arazyme blocked the secretion of thymus and activation‑regulated chemokine (TARC)/CCL17, MCP‑1, IL‑6 and IL‑8 due to tumor necrosis factor‑α (TNF‑α) and interferon‑γ (IFN‑γ) in HaCaT cells. TNF‑α and IFN‑γ suppressed the expression of skin barrier proteins, including filaggrin, involucrin and loricrin. By contrast, arazyme increased the expression of filaggrin, involucrin and loricrin. These results may contribute to the development of a therapeutic drug for the treatment of allergic diseases, including atopic dermatitis.

The pathologic and clinical intersection of atopic and autoimmune disease

Hypersensitivity reactions of the immune system have been broadly categorized into the atopic and autoimmune depending on whether the antigen triggering the reaction is endogenous (or self) or exogenous, the types of cellular and humoral components involved, and the clinical symptoms. Research into the pathophysiology of the resultant disease states has focused on a dichotomy between Th1 and Th2 T helper lymphocytes thought to govern autoimmune and atopic disease, respectively. Recent discoveries, however, have served to dispute this paradigm and have provided additional insight into the roles of Th17 cells, B-lymphocytes and T regulatory cells as well as the considerable communication and commonalities between the complex signaling pathways. Furthermore, clinical studies have served to challenge the idea that the presence of atopy and autoimmunity are mutually exclusive states. Finally, application of recent approaches to treatment-biologic targeted therapy in autoimmunity and induction of immune tolerance in atopic disease--to both disease states have shown mixed but promising results.