A modular view of cytokine networks in atopic dermatitis

Canine amniotic membrane-derived mesenchymal stem cells ameliorate atopic dermatitis through regeneration and immunomodulation

Mesenchymal stem cells (MSCs) are a promising tool for treating immune disorders. However, the immunomodulatory effects of canine MSCs compared with other commercialized biologics for treating immune disorders have not been well studied. In this study we investigated the characteristics and immunomodulatory effects of canine amnion membrane (cAM)-MSCs. We examined gene expression of immune modulation and T lymphocytes from activated canine peripheral blood mononuclear cell (PBMC) proliferation. As a result, we confirmed that cAM-MSCs upregulated immune modulation genes (TGF-β1, IDO1 and PTGES2) and suppressed the proliferation capacity of T cells. Moreover, we confirmed the therapeutic effect of cAM-MSCs compared with oclacitinib (OCL), the most commonly used Janus kinase (JAK) inhibitor, as a treatment for canine atopic dermatitis (AD) using a mouse AD model. As a result, we confirmed that cAM-MSCs with PBS treatment groups (passage 4, 6 and 8) compared with PBS only (PBS) though scores of dermatologic signs, tissue pathologic changes and inflammatory cytokines were significantly reduced. In particular, cAM-MSCs were more effective than OCL in the recovery of wound dysfunction, regulation of mast cell activity and expression level of immune modulation protein. Interestingly, subcutaneous injection of cAM-MSCs induced weight recovery, but oral administration of oclacitinib induced weight loss as a side effect. In conclusion, this study suggests that cAM-MSCs can be developed as a safe canine treatment for atopic dermatitis without side effects through effective regeneration and immunomodulation.

Transcriptome-based identification of novel endotypes in adult atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a frequent and heterogeneous inflammatory skin disease, for which personalized medicine remains a challenge. High-throughput approaches have improved understanding of the complex pathophysiology of AD. However, a purely data-driven AD classification is still lacking.

METHODS

To address this question, we applied an original unsupervised approach on the largest available transcriptome dataset of AD lesional (n = 82) and healthy (n = 213) skin biopsies.

RESULTS

Taking into account pathological and physiological state, a variance-based filtering revealed 222 AD-specific hyper-variable genes that efficiently classified the AD samples into 4 clusters that turned out to be clinically and biologically distinct. Comparison of gene expressions between clusters identified 3 sets of upregulated genes used to derive metagenes (MGs): MG-I (19 genes) was associated with IL-1 family signaling (including IL-36A and 36G) and skin remodeling, MG-II (23 genes) with negative immune regulation (including IL-34 and 37) and skin architecture, and MG-III (17 genes) with B lymphocyte immunity. Sample clusters differed in terms of disease severity (p = .02) and S. aureus (SA) colonization (p = .02). Cluster 1 contained the most severe AD, highest SA colonization, and overexpressed MG-I. Cluster 2 was characterized by less severe AD, low SA colonization, and high MG-II expression. Cluster 3 included mild AD, mild SA colonization, and mild expression of all MGs. Cluster 4 had the same clinical features as cluster 3 but had hyper-expression of MG-III. Last, we successfully validated our method and results in an independent cohort.

CONCLUSION

Our study revealed unrecognized AD endotypes with specific underlying biological pathways, highlighting novel pathophysiological mechanisms. These data could provide new insights into personalized treatment strategies.

Granzyme B in Epithelial Barrier Dysfunction and Related Skin Diseases

The predominant function of the skin is to serve as a barrier - to protect against external insults and to prevent water loss. Junctional and structural proteins in the stratum corneum, the outermost layer of the epidermis, are critical to the integrity of the epidermal barrier as it balances ongoing outward migration, differentiation, and desquamation of keratinocytes in the epidermis. As such, epidermal barrier function is highly susceptible to upsurges of proteolytic activity in the stratum corneum and epidermis. Granzyme B is a serine protease scarce in healthy tissues but present at high levels in tissues encumbered by chronic inflammation. Discovered in the 1980s, Granzyme B is currently recognized for its intracellular roles in immune cell-mediated targeted apoptosis as well as extracellular roles in inflammation, chronic injuries, tissue remodeling, and processing of cytokines, matrix proteins, and autoantigens. Increasing evidence has emerged in recent years supporting a role for Granzyme B in promoting barrier dysfunction in the epidermis by direct cleavage of barrier proteins and eliciting immunoreactivity. Likewise, Granzyme B contributes to impaired epithelial function of the airways, retina, gut and vessels. In the present review, the role of Granzyme B in cutaneous epithelial dysfunction is discussed in the context of specific conditions with an overview of underlying mechanisms as well as utility of current experimental and therapeutic inhibitors.

Effect of Lactic Acid Strains Isolated from Kimchi on Atopic Dermatitis and Immunomodulation in NC/Nga Mice

Kimchi is a traditional Korean food, of which its constituent lactic acid bacteria have been reported to possess various physiological activities. However, few studies have investigated the immunological activity of these bacteria or their effect on atopic dermatitis (AD). We investigated whether a mixture of 6 types of lactic acid bacteria strains (LBS) isolated from kimchi has an immunomodulating effect on atopy. Mice with atopic dermatitis were orally administered LSB from kimchi for 8 weeks, and skin moisture content, scratching behavior, T-and B-cell proliferation, Th1/2 cytokines, and serum IgE and histamine levels were measured. In addition, hematoxylin and eosin and toluidine blue staining were con-ducted. Mice receiving LBS from kimchi had increased skin moisture content (164.3%) and T-cell proliferation (more than 4-fold), and decreased number of scratching behaviors (78.2%) and B-cell proliferation (63.7%) compared with the 2,4-dinitrochlorobenzene control group. In addition, LBS increased Th1 type cytokines, decreased Th2 type and pro-inflam-matory cytokines, and decreased blood IgE (70.4%), histamine (67.6%) and mast cell levels. Therefore, it suggests that LBS of kimchi may be helpful in improving AD caused by immunological imbalance.

Oclacitinib, a Janus Kinase Inhibitor, Reduces the Frequency of IL-4- and IL-10-, but Not IFN-γ-, Producing Murine CD4+ and CD8+ T Cells and Counteracts the Induction of Type 1 Regulatory T Cells

The purpose of the present study was to broaden the knowledge and understanding of the effects of oclacitinib (OCL), a Janus kinase inhibitor, on T cells in the context of both the immune mechanisms underlying anti-inflammatory and anti-allergic properties of the drug and its safety. The results indicate that beneficial effects of OCL in the treatment of skin allergic diseases may be partially mediated by the inhibition of IL-4 production in CD4+ and CD8+ T cells. To a certain extent, the antiproliferative effect of OCL on CD8+ T cells may also contribute to its therapeutic effect. The study found that OCL does not affect the proliferation of CD4+ T cells or the number of IFN-γ- and IL-17-producing CD4+ and CD8+ T cells. Moreover, OCL was found to counteract the induction of type 1 regulatory T (Tr1) cells and to act as a strong inhibitor of IL-10 production in both CD4+ and CD8+ T cells. Thus, these results indicate that beneficial effects of OCL in the treatment of skin allergic diseases are not mediated through: (a) the abolishment of IFN-γ and IL-17-production in CD4+ and CD8+ T cells; (b) generation of Tr1 cells; (c) inhibition of CD4+ T cell proliferation; (d) induction of IL-10 production in CD4+ T cells. The results of this study strongly suggest that, with respect to the evaluated parameters, OCL exerts a suppressive effect on Th2- but not Th1-mediated immunity.

Periostin in Allergy and Inflammation

Matricellular proteins are involved in the crosstalk between cells and their environment and thus play an important role in allergic and inflammatory reactions. Periostin, a matricellular protein, has several documented and multi-faceted roles in health and disease. It is differentially expressed, usually upregulated, in allergic conditions, a variety of inflammatory diseases as well as in cancer and contributes to the development and progression of these diseases. Periostin has also been shown to influence tissue remodelling, fibrosis, regeneration and repair. In allergic reactions periostin is involved in type 2 immunity and can be induced by IL-4 and IL-13 in bronchial cells. A variety of different allergic diseases, among them bronchial asthma and atopic dermatitis (AD), have been shown to be connected to periostin expression. Periostin is commonly expressed in fibroblasts and acts on epithelial cells as well as fibroblasts involving integrin and NF-κB signalling. Also direct signalling between periostin and immune cells has been reported. The deposition of periostin in inflamed, often fibrotic, tissues is further fuelling the inflammatory process. There is increasing evidence that periostin is also expressed by epithelial cells in several of the above-mentioned conditions as well as in cancer. Augmented periostin expression has also been associated with chronic inflammation such as in inflammatory bowel disease (IBD). Periostin can be expressed in a variety of different isoforms, whose functions have not been elucidated yet. This review will discuss potential functions of periostin and its different isoforms in allergy and inflammation.

Keratinocytes-Derived Reactive Oxygen Species Play an Active Role to Induce Type 2 Inflammation of the Skin: A Pathogenic Role of Reactive Oxygen Species at the Early Phase of Atopic Dermatitis

Background

Atopic dermatitis (AD) is characterized by chronic, relapsing skin inflammation (eczema) with itchy sensation. Keratinocytes, which are located at the outermost part of our body, are supposed to play important roles at the early phase of type 2 inflammation including AD pathogenesis.

Objective

The purpose of this study was to evaluate whether keratinocytes-derived reactive oxygen species (ROS) could be produced by the allergens or non-allergens, and the keratinocytes-derived ROS could modulate a set of biomarkers for type 2 inflammation of the skin.

Methods

Normal human epidermal keratinocytes (NHEKs) were treated with an allergen of house dust mites (HDM) or a non-allergen of compound 48/80 (C48/80). Then, biomarkers for type 2 inflammation of the skin including those for neurogenic inflammation were checked by reverse transcriptase-polymerase chain reaction and western immunoblot experiments.

Results

HDM or C48/80 was found to upregulate expression levels of our tested biomarkers, including type 2 T helper-driving pathway (KLK5, PAR2, and NFκB), epithelial-cell-derived cytokines (thymic stromal lymphopoietin, interleukin [IL]-25, IL-33), and neurogenic inflammation (NGF, CGRP). The HDM- or C-48/80-induced expression levels of the biomarkers could be blocked by an antioxidant treatment with 5 mM N-acetyl-cysteine. In contrast, pro-oxidant treatment with 1 mM H₂O₂ could upregulate expression levels of the tested biomarkers in NHEKs.

Conclusion

Our results reveal that keratinocytes-derived ROS, irrespective to their origins from allergens or non-allergens, have a potential to induce type 2 inflammation of AD skin.

Companion Animals as Models for Inhibition of STAT3 and STAT5

The use of transgenic mouse models has revolutionized the study of many human diseases. However, murine models are limited in their representation of spontaneously arising tumors and often lack key clinical signs and pathological changes. Thus, a closer representation of complex human diseases is of high therapeutic relevance. Given the high failure rate of drugs at the clinical trial phase (i.e., around 90%), there is a critical need for additional clinically relevant animal models. Companion animals like cats and dogs display chronic inflammatory or neoplastic diseases that closely resemble the human counterpart. Cat and dog patients can also be treated with clinically approved inhibitors or, if ethics and drug safety studies allow, pilot studies can be conducted using, e.g., inhibitors of the evolutionary conserved JAK-STAT pathway. The incidence by which different types of cancers occur in companion animals as well as mechanisms of disease are unique between humans and companion animals, where one can learn from each other. Taking advantage of this situation, existing inhibitors of known oncogenic STAT3/5 or JAK kinase signaling pathways can be studied in the context of rare human diseases, benefitting both, the development of drugs for human use and their application in veterinary medicine.

Elevated Gestational IL-13 During Fetal Development Is Associated With Hyperactivity and Inattention in Eight-Year-Old Children

Maternal immune activation (MIA) during fetal development leads to behavioral and psychological disorders in the offspring. Concomitantly, insufficient supply of polyunsaturated fatty acids (PUFAs) is suspected to contribute to early neuronal maldevelopment due to the immune modulatory capabilities of PUFAs. However, human data are missing considering both of these aspects and their impact on children's behavioral outcomes. In line, this study aimed to elucidate the influence of gestational cytokines and PUFA-containing lipids during late pregnancy on behavioral sequelae in childhood, particularly focusing on an immune activation shaped by a history of maternal atopic diseases instead of a pathogen-mediated immune response. Based on the prospective mother-child cohort LINA we assessed the unstimulated blood cytokine profiles and concentrations of PUFA-containing lipids of 293 mothers at the 34th week of pregnancy. Maternal history of atopic diseases was obtained from questionnaires and behavior in eight-year-old children was assessed by the standardized Strength and Difficulties Questionnaires (SDQ) generating scores for hyperactivity/inattention, emotional symptoms, conduct problems, and peer relationship problems. Elevated IL-13 increased the risk for the child to show behavioral difficulties, in particular, hyperactive/inattentive behavior [adj. OR (95% CI): 2.47 (1.51-4.02), n = 255 vs. 38] at the age of eight years. Although the presence of maternal atopic dermatitis (AD) was associated with increased gestational IL-13 concentrations [adj. MR (95% CI): 1.17 (1.04-1.32)], no effect on children's behavioral difficulties was observed. However, a decrease in the PUFA containing lipid species PC aa C38:6 was not only associated with an increased gestational IL-13 concentration but also mediated the indirect effect of low PC aa C38:6 concentrations on children's abnormal behavior independent of maternal AD. We additionally assessed whether maternal IL-13 and PC aa C38:6 concentrations translate their effect by altering children's cord blood PC aa C38:6 and IL-13. While also the children's cord blood IL-13 was related to children's behavior, no effect of children's PC aa C38:6 was observed. This is the first study demonstrating that elevated gestational IL-13 increases the risk for children to develop behavioral difficulties. Analyses suggest that a reduced supply of gestational PC aa C38:6 contributes to elevated gestational IL-13 leading to behavioral sequelae in the offspring.

The Role of Proteasome Inhibitor MG132 in 2,4-Dinitrofluorobenzene-Induced Atopic Dermatitis in NC/Nga Mice

BACKGROUND

Although immunosuppressants for therapy of atopic dermatitis (AD) are still being sought, proteasome inhibitors are also potential candidates for the treatment of AD. Proteasome inhibitors exert various effects by blocking proteasomal degradation and help regulate processes such as apoptosis induction via caspase-9, cell cycle progression via cyclins, NF-κB inactivation via IκB, and downregulation of antigen cross-presentation. The cells targeted by proteasome inhibitors are therefore activated cells undergoing proliferation or differentiation, and antigen-presenting cells carrying out protein degradation.

OBJECTIVES

This study investigated the therapeutic effects and side effects of a proteasome inhibitor, MG132, on the treatment of AD.

METHODS

AD-like disease in NC/Nga mice housed under specific pathogen-free conditions was induced by repeated application of 2,4-dinitrofluorobenzene (DNFB). Disease progression was evaluated by inflammation score, histopathology, and serum IgE level, and the effects of systemic MG132 administration were investigated. The percentages and absolute numbers for each population of Th1, Th2, and Th17 cells in the axillary lymph nodes were analyzed by flow cytometry.

RESULTS

DNFB application increased the expression of a unique major histocompatibility complex class I mutant molecule D/Ldm7 in dendritic cells (DCs), and increased Th1 and Th17 cells in NC/Nga mice. In vivo MG132 administration to NC/Nga mice with DNFB-induced dermatitis reduced Th17 cells but maintained the level of Th1 cells, resulting in the alleviation of dermatitis lesions by decreasing both serum IgE hyperproduction and mast cell migration. To understand the mechanisms maintaining Th1 cell levels following in vivo MG132-administration, we focused on the role of proteasomes regulating D/Ldm7 expression. Interestingly, 20S proteasome activity was higher in NC/Nga DCs than in BALB/c DCs. In vitro MG132 administration partially increased D/Ldm7 expression in a dose-dependent manner during DC maturation, and induced IFN-γ production from autoreactive CD8+ T cells but not from CD4+ T cells following coculturing with D/Ldm7-upregulated DCs.

CONCLUSION

Although MG132 administration temporarily alleviated AD pathogenesis in NC/Nga mice, prolonged MG132 treatment may result in immunopathogenesis leading to chronic AD due to its side effect of maintaining Th1 levels via autoreactive CD8+ T cells.

The prevention of TNF-α/IFN-γ mixture-induced inflammation in human keratinocyte and atopic dermatitis-like skin lesions in Nc/Nga mice by mineral-balanced deep sea water

Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by environmental and chemical allergens. Despite the complexity of its pathogenesis, many investigations have shown that substances having anti-inflammatory activities alleviated the pathology of AD. Here, we evaluated the effects of mineral-balanced deep sea water (DSW) on AD-like skin damage in both in vitro and in vivo. The results showed that mineral-balanced DSW regressed inflammatory chemokines, such as macrophage-derived chemokine (MDC), thymus- and activation-regulated chemokine (TARC) and regulated on activation, normal T-cell expressed and secreted (RANTES), and cytokines, interleukin (IL)-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA expression in HaCaT immortal human keratinocyte treated with tumor necrosis factor (TNF)-α/ interferon (IFN)-γ mixture. Furthermore, increased cyclooxygenase (COX)-2 protein expressions were also reversed, filaggrin gene expression was enhanced and decreased involucrin transcriptions was recovered by mineral-balanced DSW in TNF-α/IFN-γ mixture-treated HaCaT human keratinocyte. Moreover, we revealed that the inhibitory effects of mineral-balanced DSW were mediated with the suppression of signal transducer and activator of transcription (STAT) 1 phosphorylation. In animal experiments, we showed that hardness 2000 of mineral-balanced DSW decreased the serum levels of IgE, IL-4, and histamine, and alleviated the severity score and numbers of scratching in dinitrochlorobezene (DNCB)-treated Nc/Nga mice. Furthermore, increased epidermal thickness and mast cell infiltration by DNCB treatment were reversed by the application of hardness 2000 mineral-balanced DSW. Taken together, the present investigation indicates that mineral-balanced DSW is a potent substance with anti-atopic dermatitis activity.

Attention deficit hyperactivity disorder may be a highly inflammation and immune-associated disease (Review)

Attention deficit hyperactivity disorder (ADHD) is a common behavioral disorder. Previous research has indicated that genetic factors, family education, environment and dietary habits are associated with ADHD. It has been determined that in China many children with ADHD also have allergic rhinitis or asthma. These children are more susceptible to the common cold or upper respiratory infections compared with normal healthy children. Additionally, the common cold or an upper respiratory infection may lead to disease recurrence or worsen the symptoms in these children. Previous studies have determined that ADHD may have a close association with allergic disease. Based on the clinically observed phenomenon and previous studies, it was hypothesized that ADHD is a high inflammation and immune‑associated disease. Therefore, the authors designed clinical and animal experiments to test this hypothesis in the future. Immune system disorders may be a novel part of the etiology of ADHD. The current report may have implications for future clinical practice.

Effect of isosecotanapartholide isolated from Artemisia princeps Pampanini on IL‑33 production and STAT‑1 activation in HaCaT keratinocytes

The present study aimed to investigate the anti‑inflammatory effect and mechanism of action of isosecotanapartholide (ISTP), isolated from Artemisia princeps Pampanini extract (APE). The effects of ISTP and APE on the proliferation of human keratinocytes following stimulation by tumor necrosis factor‑α/interferon‑γ were assessed. ISTP and APE downregulated the expression levels of signal transducer and activator of transcription‑1 (STAT‑1), and reduced interleukin‑33 (IL‑33) production. ISTP and APE inhibited the mRNA expression levels of thymus and activation‑regulated chemokine (TARC/CCL17) in a dose‑dependent manner. Western blot analysis demonstrated that ISTP and APE dose‑dependently inhibited protein expression levels of intercellular adhesion molecule‑1 and phosphorylation of STAT‑1. The results of the present study indicate that ISTP may inhibit TARC/CCL17 production in human epidermal keratinocytes via the STAT‑1 signaling pathway and may be associated with the inhibition of IL‑33 production. The current study indicated that ISTP is an active component in APE and may be a potential therapeutic agent for the treatment of inflammatory skin disorders.

Control of the Physical and Antimicrobial Skin Barrier by an IL-31-IL-1 Signaling Network

Atopic dermatitis, a chronic inflammatory skin disease with increasing prevalence, is closely associated with skin barrier defects. A cytokine related to disease severity and inhibition of keratinocyte differentiation is IL-31. To identify its molecular targets, IL-31-dependent gene expression was determined in three-dimensional organotypic skin models. IL-31-regulated genes are involved in the formation of an intact physical skin barrier. Many of these genes were poorly induced during differentiation as a consequence of IL-31 treatment, resulting in increased penetrability to allergens and irritants. Furthermore, studies employing cell-sorted skin equivalents in SCID/NOD mice demonstrated enhanced transepidermal water loss following s.c. administration of IL-31. We identified the IL-1 cytokine network as a downstream effector of IL-31 signaling. Anakinra, an IL-1R antagonist, blocked the IL-31 effects on skin differentiation. In addition to the effects on the physical barrier, IL-31 stimulated the expression of antimicrobial peptides, thereby inhibiting bacterial growth on the three-dimensional organotypic skin models. This was evident already at low doses of IL-31, insufficient to interfere with the physical barrier. Together, these findings demonstrate that IL-31 affects keratinocyte differentiation in multiple ways and that the IL-1 cytokine network is a major downstream effector of IL-31 signaling in deregulating the physical skin barrier. Moreover, by interfering with IL-31, a currently evaluated drug target, we will have to consider that low doses of IL-31 promote the antimicrobial barrier, and thus a complete inhibition of IL-31 signaling may be undesirable.

Combinatorial code governing cellular responses to complex stimuli

Cells adapt to their environment through the integration of complex signals. Multiple signals can induce synergistic or antagonistic interactions, currently considered as homogenous behaviours. Here, we use a systematic theoretical approach to enumerate the possible interaction profiles for outputs measured in the conditions 0 (control), signals X, Y, X+Y. Combinatorial analysis reveals 82 possible interaction profiles, which we biologically and mathematically grouped into five positive and five negative interaction modes. To experimentally validate their use in living cells, we apply an original computational workflow to transcriptomics data of innate immune cells integrating physiopathological signal combinations. Up to 9 of the 10 defined modes coexisted in context-dependent proportions. Each interaction mode was preferentially used in specific biological pathways, suggesting a functional role in the adaptation to multiple signals. Our work defines an exhaustive map of interaction modes for cells integrating pairs of physiopathological and pharmacological stimuli.

Cells constantly integrate information from multiple stimuli. By considering every possible means by which two stimuli can interact, Cappuccio et al. define 10 interaction modes and demonstrate their preferential use by dendritic cells responding to different combinations of microbial and host inflammatory cues.

Alantolactone from Saussurea lappa Exerts Antiinflammatory Effects by Inhibiting Chemokine Production and STAT1 Phosphorylation in TNF-α and IFN-γ-induced in HaCaT cells

Skin inflammation is the most common condition seen in dermatology practice and can be caused by various allergic reactions and certain toxins or chemicals. In the present study, we investigated the antiinflammatory effects of Saussurea lappa, a medicinal herb, and its marker compounds alantolactone, caryophyllene, costic acid, costunolide, and dehydrocostuslactone in the HaCaT human keratinocyte cell line. HaCaT cells were stimulated with tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ), and treated with S. lappa or each of five marker compounds. Chemokine production and expression were analyzed by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction, respectively. Phosphorylation of signal transducer and activator of transcription (STAT) 1 was determined by immunoblotting. Stimulation with TNF-α and IFN-γ significantly increased the production of the following chemokines: thymus-regulated and activation-regulated chemokine (TARC): regulated on activation, normal T-cell expressed and secreted (RANTES): macrophage-derived chemokine (MDC): and interleukin-8 (IL-8). By contrast, S. lappa and the five marker compounds significantly reduced the production of these chemokines by TNF-α and IFN-γ-treated cells. S. lappa and alantolactone suppressed the TNF-α and IFN-γ-stimulated increase in the phosphorylation of STAT1. Our results demonstrate that alantolactone from S. lappa suppresses TNF-α and IFN-γ-induced production of RANTES and IL-8 by blocking STAT1 phosphorylation in HaCaT cells.

Human sebum extract induces barrier disruption and cytokine expression in murine epidermis

BACKGROUND

Previous studies have shown that human sebum may play a role in barrier function but with much debate.

OBJECTIVE

To elucidate the effects of human sebum on skin barrier function.

METHODS

We used hairless mouse skin to study the functional and morphological alternation of epidermis after the application of human sebum.

RESULTS

The results showed a significant increase in transepidermal water loss and erythema value, and a decrease in skin hydration, accompanied by epidermal hyperplasia with parakeratosis following sebum application. Nile red staining together with electron microscopic examination confirmed the underlying mechanisms for sebum-induced barrier disruption are related directly to the interaction of sebum with the intracellular lipid lamellae of the SC, thereby leading to the increase in the fluidity of SC intracellular lipids as demonstrated by ATR-FTIR measurement. An inflammatory reaction characterized by an enhanced cytokine cascade, including up-regulation of TNF-α, IL-1α and IL-6, was also observed. On the other hand, there were insignificant expression of thymic stromal lymphopoietin and unchanged serum levels of IgE, suggesting non-immunogenic stimulation by sebum treatment.

CONCLUSION

It may be concluded that inflammation induced by excess amount of sebum is more likely an irritant contact dermatitis rather than an allergic one. Moreover, these findings implicated possible relationships between sebum, irritant contact dermatitis, and seborrheic dermatitis.

A blinded, randomized, placebo-controlled trial of the efficacy and safety of the Janus kinase inhibitor oclacitinib (Apoquel®) in client-owned dogs with atopic dermatitis

Background

Pruritus is the hallmark clinical sign of atopic dermatitis (AD) in dogs. Preliminary study results suggest that oclacitinib, a selective Janus kinase inhibitor, could reduce pruritus and associated inflammatory skin lesions in dogs with AD.

Hypothesis/Objectives

The objective was to evaluate efficacy and safety of oclacitinib (Apoquel^®) for the control of AD in a randomized, double‐blind, placebo‐controlled trial.

Animals

Clinicians at 18 specialty clinics enrolled client‐owned dogs (n = 299) with a history of chronic AD.

Methods

Dogs were randomized to receive either oclacitinib (0.4–0.6 mg/kg twice daily for 14 days and then once daily for up to 112 days) or an excipient‐matched placebo. Owners assessed visual analog scale (VAS) scores of pruritus on days 0, 1, 2, 7, 14, 28, 56, 84 and 112. Clinicians assessed Canine AD Extent and Severity Index (CADESI‐02) scores on days 0, 14, 28, 56, 84 and 112.

Results

On days 1, 2, 7, 14 and 28, oclacitinib‐treated dogs had a 29.5, 42.3, 61.5, 66.7 and 47.4% reduction from baseline in owner‐assessed pruritus scores, respectively, compared with a 6.5, 9.1, 6.5, 3.9 and 10.4% reduction in placebo‐treated dogs. On days 14 and 28, dermatologists recorded a 48.4% reduction in CADESI‐02 scores in oclacitinib‐treated dogs compared with a 1.7% reduction and a 3.6% increase in placebo‐treated dogs. After day 28, >86% of all placebo‐treated dogs had moved to an open‐label study, making between‐group comparisons biased. Differences were significant at all time points assessed (P < 0.0001).

Conclusions and clinical importance

Oclacitinib provided rapid, effective and safe control of AD, with substantial improvement in VAS and CADESI‐02 scores.

In ovo delivery of Newcastle disease virus conjugated hybrid calcium phosphate nanoparticle and to study the cytokine profile induction

In this report, the hybrid calcium phosphate (CaP) nanoparticles were synthesized and functionalized with Newcastle disease virus (NDV). These nanoparticles were synthesized by a combination of co-precipitation and polymerization process and functionalized with amino propyl triethoxy silane before coupling to NDV. The 5-dimethylthiazol-2-yl-2, 5-diphenyltetrazolium bromide (MTT) assay of chicken spleen cells incubated with these nanoparticles indicated that, these particles did not exert any significant cytotoxicity. The effects of hybrid CaP nanoparticles on cell cycle were assayed using a flow cytometer. The results demonstrated that the cell viability and proliferation capacity of spleen cells were not affected by hybrid CaP nanoparticles compared with their control cells. The hybrid CaP nanoparticles were characterized by scanning/transmission electron microscopy (SEM/TEM); Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction patterns (XRD), Raman spectroscopy and energy-dispersive X-ray spectroscopy (EDX). These methods revealed that NDV was successfully conjugated on nanoparticles. The ability of the hybrid CaP nanoparticles to induce different cytokine mRNAs in the spleen cells of 18-day old embryonated chicken eggs (ECEs) was studied by quantitative real time polymerase chain reaction (qRT-PCR). NDV conjugated particles induced a high expression of Th1 cytokines such as interferon (IFN)-α, tumor necrosis factor (TNF)-α of and Th2 cytokines, interleukin (IL) 6 and IL-10. Uncoupled NDV induced only Th1 cytokines, IFN-α, INF-γ and TNF-α. The hybrid particles alone did not induce any cytokines. This confirmed that nanoparticle coupling could induce differential cytokine profiles and hence can be used as an alternate strategy to direct favorable immune responses in animals or chickens using appropriate vaccination carrier.

Periostin levels correlate with disease severity and chronicity in patients with atopic dermatitis

BACKGROUND

Recent findings indicate that periostin, an extracellular matrix protein induced by T helper 2 cytokines, plays a critical role in the pathogenesis of atopic dermatitis (AD).

OBJECTIVES

To determine whether serum periostin level is associated with clinical phenotype in adult patients with AD.

METHODS

An enzyme-linked immunosorbent assay was performed to determine serum periostin levels in 257 adult patients with AD, 66 patients with psoriasis vulgaris (PV) as a disease control and 25 healthy controls. Serum periostin levels were analysed together with clinical characteristics and laboratory parameters, including thymus and activation-regulated chemokine (TARC), lactate dehydrogenase (LDH), blood eosinophil count and total IgE. Immunohistochemical analysis evaluated the expression of periostin in association with various clinical phenotypes of AD. The effect of treatment on serum periostin level was also assessed.

RESULTS

Serum periostin was significantly higher in patients with AD than in patients with PV and healthy controls. Periostin level was found to be positively correlated with disease severity, TARC level, LDH level and eosinophil count, but not with IgE level. Higher serum periostin level was observed in patients with extrinsic AD compared with patients with intrinsic AD; the positive correlation of disease severity disappeared in patients with intrinsic AD. Robust expression of periostin was detected in the dermis of patients with AD with erythroderma, lichenification and, to a lesser extent, scaly erythema. Serial measurement of serum periostin revealed decreased levels of periostin after treatment for AD.

CONCLUSIONS

Periostin may play a critical role in disease severity and chronicity in the pathogenesis of AD.

Oclacitinib (APOQUEL(®)) is a novel Janus kinase inhibitor with activity against cytokines involved in allergy

Janus kinase (JAK) enzymes are involved in cell signaling pathways activated by various cytokines dysregulated in allergy. The objective of this study was to determine whether the novel JAK inhibitor oclacitinib could reduce the activity of cytokines implicated in canine allergic skin disease. Using isolated enzyme systems and in vitro human or canine cell models, potency and selectivity of oclacitinib was determined against JAK family members and cytokines that trigger JAK activation in cells. Oclacitinib inhibited JAK family members by 50% at concentrations (IC50 's) ranging from 10 to 99 nm and did not inhibit a panel of 38 non-JAK kinases (IC50 's > 1000 nM). Oclacitinib was most potent at inhibiting JAK1 (IC50 = 10 nM). Oclacitinib also inhibited the function of JAK1-dependent cytokines involved in allergy and inflammation (IL-2, IL-4, IL-6, and IL-13) as well as pruritus (IL-31) at IC50 's ranging from 36 to 249 nM. Oclacitinib had minimal effects on cytokines that did not activate the JAK1 enzyme in cells (erythropoietin, granulocyte/macrophage colony-stimulating factor, IL-12, IL-23; IC50 's > 1000 nM). These results demonstrate that oclacitinib is a targeted therapy that selectively inhibits JAK1-dependent cytokines involved in allergy, inflammation, and pruritus and suggests these are the mechanisms by which oclacitinib effectively controls clinical signs associated with allergic skin disease in dogs.

The role of oxidation in FSL-1 induced signaling pathways of an atopic dermatitis model in HaCaT keratinocytes

Oxidative stress (OS) is common in inflammatory conditions and may be important in atopic dermatitis (AD) etiology. The aim of this project was to study the involvement of oxidation in FSL-1 (deacylated lipoprotein)-triggered signaling pathways leading to AD-typical cytokine expression in HaCaT keratinocytes. HaCaT keratinocytes, pretreated with the inhibitor to OS N-acetylcysteine (NAC), were exposed to FSL-1, a stimulator of AD-related cytokines. Cytokines expression was studied by real time polymerase chain reaction (PCR); nuclear factor-kappa B (NF-κB) and p38 mitogen activated protein kinase (MAPK) activities were studied by western blotting; and the oxidative state of cells was determined by the dichlorofluorescein (DCF) assay. We found that endogenous OS in keratinocytes appeared 4 h after FSL-1 administration. OS activated NF-κB, but not p38 MAPK, and the inhibition of OS reduced FSL-1 induced interleukin (IL) 33, thymic stromal lymphopoietin (TSLP) and TNFα mRNA expression. We conclude that FSL-1 triggers an OS reaction in HaCaT keratinocytes, which is probably a secondary event affecting the expression of specific AD typical cytokines, possibly through the NF-κB pathways. This role of OS in the inflammatory response in AD is worth further investigating.

Saussurea lappa alleviates inflammatory chemokine production in HaCaT cells and house dust mite-induced atopic-like dermatitis in Nc/Nga mice

Saussurea lappa is a traditional herbal medicine used for to treat various inflammatory diseases. In this study, we investigated the protective effects of S. lappa against atopic dermatitis using human keratinocyte HaCaT cells, murine mast cell line MC/9 cells, and a house dust mite-induced atopic dermatitis model of Nc/Nga mice. Treatment with the S. lappa caused a significant reduction in the mRNA levels and production of inflammatory chemokines and cytokine, including thymus- and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), regulated on activation, normal T-cell expressed and secreted (RANTES), and interleukin-8 (IL-8) in tumor necrosis factor-α/interferone-γ-stimulated HaCaT cells. S. lappa exhibited the significant reduction in histamine production in MC/9 cells. In the atopic dermatitis model, S. lappa significantly reduced the dermatitis score and serum IgE and TARC levels. In addition, the back skin and ears of S. lappa-treated Nc/Nga mice exhibited reduced histological manifestations of atopic skin lesions such as erosion, hyperplasia of the epidermis and dermis, and inflammatory cell infiltration. In conclusion, an extract of S. lappa effectively suppressed the development of atopic dermatitis, which was closely related to the reduction of chemokines and cytokine. Our study suggests that S. lappa may be a potential treatment for atopic dermatitis.

Efficacy and safety of oclacitinib for the control of pruritus and associated skin lesions in dogs with canine allergic dermatitis

BACKGROUND

Oclacitinib (Apoquel(®) ) inhibits the function of a variety of pro-inflammatory, pro-allergic and pruritogenic cytokines that are dependent on Janus kinase enzyme activity. Oclacitinib selectively inhibits Janus kinase 1.

HYPOTHESIS/OBJECTIVES

We aimed to evaluate the safety and efficacy of oclacitinib for the control of pruritus associated with allergic dermatitis in a randomized, double-blinded, placebo-controlled trial.

METHODS

Client-owned dogs (n = 436) with moderate to severe owner-assessed pruritus and a presumptive diagnosis of allergic dermatitis were enrolled. Dogs were randomized to either oclacitinib at 0.4-0.6 mg/kg orally twice daily or an excipient-matched placebo. An enhanced 10 cm visual analog scale (VAS) was used by the owners to assess the severity of pruritus from day 0 to 7 and by veterinarians to assess the severity of dermatitis on days 0 and 7. Dogs could remain on the study for 28 days.

RESULTS

Pretreatment owner and veterinary VAS scores were similar for the two treatment groups. Oclacitinib produced a rapid onset of efficacy within 24 h. Mean oclacitinib Owner Pruritus VAS scores were significantly better than placebo scores (P < 0.0001) on each assessment day. Pruritus scores decreased from 7.58 to 2.59 cm following oclacitinib treatment. The day 7 mean oclacitinib Veterinarian Dermatitis VAS scores were also significantly better (P < 0.0001) than placebo scores. Diarrhoea and vomiting were reported with similar frequency in both groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

In this study, oclacitinib provided rapid, effective and safe control of pruritus associated with allergic dermatitis, with owners and veterinarians noting substantial improvements in pruritus and dermatitis VAS scores.

Topical application of a vitamin D analogue exacerbates atopic dermatitis and induces the atopic dermatitis-like phenotype in Stat6VT mice

Calcipotriene is a topical vitamin D3 analogue approved for the treatment of plaque and scalp psoriasis. We report the case of a 2-year-old boy whose atopic dermatitis (AD) flared in response to application of calcipotriene 0.005% cream and solution for a mistaken diagnosis of plaque and scalp psoriasis. We investigated whether the patient's eruption was secondary to an allergic contact dermatitis. In the Stat6VT mouse model of AD we tested whether calcipotriene could induce the otherwise-spontaneous AD-like phenotype. Closed patch testing was done on the patient with calcipotriene solution and cream, moisturizing cream, and 51% isopropanol. Stat6VT and wild-type (WT) mice were treated for 7 days with calcipotriene solution or vehicle (isopropanol) applied to the right and left upper back skin, respectively, after which mice were followed longitudinally for 10 weeks. Biopsy specimens from prior treatment sites were then collected for histology and RNA isolation. RNA was analyzed for interleukin (IL-4) expression using quantitative polymerase chain reaction. Patch testing was negative. Stat6VT mice, in contrast to WT mice, developed a persistent eczematous dermatitis at sites of calcipotriene application. Clinical and histologic features and high IL-4 transcript levels were consistent with the spontaneous AD-like phenotype seen in Stat6VT mice. At sites of active disease, calcipotriene can worsen a flare of AD. In Stat6VT mice, calcipotriene can induce the AD-like phenotype.

Histamine induces proliferation in keratinocytes from patients with atopic dermatitis through the histamine 4 receptor

BACKGROUND

Epidermal hyperproliferation resulting in acanthosis is an important clinical observation in patients with atopic dermatitis, and its underlying mechanisms are not completely understood.

OBJECTIVE

Because increased levels of histamine are present in lesional skin, we investigated the effect of histamine, especially with regard to histamine 4 receptor (H4R) activation, on the proliferation of human and murine keratinocytes.

METHODS

The expression of H4R on human and murine keratinocytes was detected by using real-time PCR. Keratinocyte proliferation was evaluated by using different in vitro cell proliferation assays, scratch assays, and measurement of the epidermal thickness of murine skin.

RESULTS

We detected H4R mRNA on foreskin keratinocytes and on outer root sheath keratinocytes; H4R mRNA was more abundant in keratinocytes from patients with atopic dermatitis compared with those from nonatopic donors. Stimulation of foreskin keratinocytes, atopic dermatitis outer root sheath keratinocytes, and H4R-transfected HaCaT cells with histamine and H4R agonist resulted in an increase in proliferation, which was blocked with the H4R-specific antagonist JNJ7777120. Abdominal epidermis of H4R-deficient mice was significantly thinner, and the in vitro proliferation of keratinocytes derived from H4R-deficient mice was lower compared with that seen in control mice. Interestingly, we only detected H4R expression on murine keratinocytes after stimulation with LPS and peptidoglycan.

CONCLUSION

H4R is highly expressed on keratinocytes from patients with atopic dermatitis, and its stimulation induces keratinocyte proliferation. This might represent a mechanism that contributes to the epidermal hyperplasia observed in patients with atopic dermatitis.

The cutaneous innate immune response in patients with atopic dermatitis

Orchestrating when and how the cutaneous innate immune system should respond to commensal or pathogenic microbes is a critical function of the epithelium. The cutaneous innate immune system is a key determinant of the physical, chemical, microbial, and immunologic barrier functions of the epidermis. A malfunction in this system can lead to an inadequate host response to a pathogen or a persistent inflammatory state. Atopic dermatitis is the most common inflammatory skin disorder and characterized by abnormalities in both skin barrier structures (stratum corneum and tight junctions), a robust T(H)2 response to environmental antigens, defects in innate immunity, and an altered microbiome. Many of these abnormalities may occur as the consequence of epidermal dysfunction. The epidermis directly interfaces with the environment and, not surprisingly, expresses many pattern recognition receptors that make it a key player in cutaneous innate immune responses to skin infections and injury. This review will discuss the role epidermal innate receptors play in regulation of skin barriers and, where possible, discuss the relevance of these findings for patients with atopic dermatitis.

ST2 regulates allergic airway inflammation and T-cell polarization in epicutaneously sensitized mice

IL-33 is an inducer of proinflammatory and T-helper type 2 (Th2) cytokines, which have an important role in atopic dermatitis (AD) and allergic asthma. ST2 is a specific receptor for IL-33 and is expressed on Th2 cells, eosinophils and mast cells. A murine model of AD was used to characterize the role of ST2 in allergen-induced skin inflammation and allergic asthma. ST2-/- and wild-type (WT) mice were epicutaneously sensitized with ovalbumin (OVA) and staphylococcal enterotoxin B, and intranasally challenged with OVA. ST2-/- mice exhibited increased production of IFNγ and increased number of CD8(+) T cells in the sensitized skin and in the airways compared with WT mice. The number of eosinophils was decreased, and Th2 cytokines were downregulated in the airways of epicutaneously sensitized ST2-/- mice compared with WT controls. However, dermal eosinophil numbers were as in WT, and the levels of Th2 cytokines were even elevated in the sensitized skin of ST2-/- mice. ST2-/- mice had elevated numbers of neutrophils and macrophages and increased levels of proinflammatory cytokines in the sensitized skin. The role of ST2 differs between different target tissues: ST2 is dispensable for the development of Th2 response in the sensitized skin, whereas it is a main inducer of Th2 cytokines in asthmatic airways.

The practical understanding and treatment of asthma

Asthma is a syndrome which is seen by physicians in nearly every specialty and affects millions of people throughout the world. Although the geoepidemiology with respect to prevalence and incidence of asthma does vary, even under the most mild of circumstance, asthma is among the leading causes of school absenteeism, work loss, and physician visits. In the past, it was considered primarily a disorder of childhood. Hence, the adage that children outgrow their asthma. We now realize that children really only outgrow their pediatrician and the genetic predisposition to asthma and bronchial hyperactivity persists throughout life. This issue is devoted to key papers that focus on important clinical problems in allergies and asthma. This issue is dedicated to helping the many sufferers of asthma with the hope that this topic will eventually become a medical anachronism.

Psychoendocrine and psychoneuroimmunological mechanisms in the comorbidity of atopic eczema and attention deficit/hyperactivity disorder

Epidemiological data indicate that atopic eczema (AE) in infancy significantly increases the risk for attention deficit/hyperactivity disorder (ADHD) in later life. The underlying pathophysiological mechanisms of this comorbidity are unknown. We propose that the release of inflammatory cytokines caused by the allergic inflammation and/or elevated levels of psychological stress as a result of the chronic disease interfere with the maturation of prefrontal cortex regions and neurotransmitter systems involved ADHD pathology. Alternatively, increased stress levels in ADHD patients may trigger AE via neuroimmunological mechanisms. In a third model, AE and ADHD may be viewed as two separate disorders with one or more shared risk factors (e.g., genetics, prenatal stress) that increase the susceptibility for both disorders leading to the co-occurrence of AE and ADHD. Future investigation of these three models may lead to a better understanding of the mechanisms underlying the observed comorbidity between AE and ADHD and further, to targeted interdisciplinary primary prevention and treatment strategies.

IL-4 up-regulates epidermal chemotactic, angiogenic, and pro-inflammatory genes and down-regulates antimicrobial genes in vivo and in vitro: relevant in the pathogenesis of atopic dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease. Although the pathogenesis of AD is not fully understood, we and others have shown that IL-4 plays a key role. In this study we aimed to identify keratinocyte genes regulated by IL-4 that may play important roles in the pathophysiology of AD. HaCat cells were treated with IL-4 at various concentrations for 24h, and PCR gene array on inflammation/autoimmunity was performed three times for analysis of differential gene expression. Of all the 370 genes examined, 32 and 53 genes are up- and down-regulated, respectively. Specifically related to AD, chemokines CCL3L1, CCL8, CCL24, CCL25, CCL26, CXCL6 and CXCL16 are up-regulated by IL-4. Pro-inflammatory factors, such as IL-19, IL-20, IL-1α, IL-12Rβ2, IL-25, IL-31RA, OSMR and nitric oxide synthase 2, are also up-regulated. In addition, IL-4 up-regulates VEGFA, a pro-angiogenic factor. In contrast, antimicrobial peptides (AMPs) or factors involved in APM production, such as IFN-κ, S100s, Toll-like receptors, and several chemokines are down-regulated. Similarly IL-4 also down-regulates TNF-α, lymphotoxin-β, an IgE suppressor, TNFSF18, a T-cells function regulator, and the glucocorticoid receptor. On the in vivo level, real-time RT-PCR on the selected genes confirmed that IL-4 up-regulates chemokines, proinflammatory cytokines while it suppresses AMP production related genes in the skin obtained from IL-4 Tg mice. Detailed examination of these genes will delineate their specific roles in chemotaxis, inflammation, angiogenesis and AMP production, all of which may contribute to the development and progression of AD.

Mixture of Polyphenols and Anthocyanins from Vaccinium uliginosum L. Alleviates DNCB-Induced Atopic Dermatitis in NC/Nga Mice

Vaccinium uliginosum L. (VU) possesses various biological properties, such as antioxidant and protective effects against VU-induced skin photoaging. The purpose of this study is to evaluate the effects of oral administration of a mixture of polyphenols and anthocyanins derived from VU on 2,4-dinitrochlorobenzene- (DNCB-) induced atopic dermatitis (AD) in NC/Nga mice. We assessed anti-AD effects in NC/Nga murine model for a period of 9 weeks. Oral administration of the mixture significantly alleviated the AD-like skin symptoms and clinical signs including ear thickness and scratching behaviors. Orally administrated mixture reduced the level of IgE and IgG1, whereas it increased the level of IgG2a in a dose-dependent manner. The calculated IgG1/IgG2a ratio for each mouse revealed that the mixture derived from VU also significantly reduced the Th2/Th1 ratio, IL-4 and IL-13 (as Th2 cytokines), IFN-γ, and IL-12 (as a Th1 cytokine) in spleens. In addition, it significantly decreased gene expression, such as IL-4, IL-5, CCR3, eotaxin-1, IL- 12, IFN-γ, MCP-1, and IL-17, in AD-like lesions and suppressed Th17. Histological analyses revealed that the epidermis thickness and number of inflammatory cells were significantly reduced. In conclusion, oral administration of the mixture in the DNCB-induced AD is confirmed to improve AD disease in mice.

IL-33: a novel danger signal system in atopic dermatitis

IL-33 is a newly recognized cytokine of the IL-1 cytokine family that has recently been attributed to the epithelial "alarmin" defense system. IL-33 is released by the epithelial cells in various tissues and organs, including keratinocytes, endothelial cells, and immune cells. Recent reports have suggested that IL-33 might be a critical part of the innate immunity, although its precise role is as yet poorly understood. In several organs, IL-33 appears to drive T helper type 2 (Th2) responses, suggesting roles in allergic and atopic diseases, as well as in fibrosis. IL-33 exerts its effects by activating the ST2 (suppression of tumorigenicity 2)/IL-1 aR receptor on different types of cells, including mast cells and Th2 cells. The ST2 receptor is either expressed on the cell surface or shed from these cells (soluble ST2, sST2), thereby functioning as a "decoy" receptor. After binding to its receptor, IL-33 activates NF-κB, suggesting that it regulates the outcome of diseases such as atopic dermatitis. On the other hand, several studies have reported on the inhibitory effects of sST2 in inflammatory and fibrotic diseases, suggesting that IL-33/ST2 is a unique cytokine with potential pro- and anti-inflammatory effects.

Periostin promotes chronic allergic inflammation in response to Th2 cytokines

Allergic inflammation triggered by exposure of an allergen frequently leads to the onset of chronic inflammatory diseases such as atopic dermatitis (AD) and bronchial asthma. The mechanisms underlying chronicity in allergic inflammation remain unresolved. Periostin, a recently characterized matricellular protein, interacts with several cell surface integrin molecules, providing signals for tissue development and remodeling. Here we show that periostin is a critical mediator for the amplification and persistence of allergic inflammation using a mouse model of skin inflammation. Th2 cytokines IL-4 and IL-13 stimulated fibroblasts to produce periostin, which interacted with αv integrin, a functional periostin receptor on keratinocytes, inducing production of proinflammatory cytokines, which consequently accelerated Th2-type immune responses. Accordingly, inhibition of periostin or αv integrin prevented the development or progression of allergen-induced skin inflammation. Thus, periostin sets up a vicious circle that links Th2-type immune responses to keratinocyte activation and plays a critical role in the amplification and chronicity of allergic skin inflammation.

IL-33 and ST2 in atopic dermatitis: expression profiles and modulation by triggering factors

In the acute phase of atopic dermatitis (AD), T-helper type 2 (Th2) cytokines characterize the inflammatory response in the skin. IL-33 is a new tissue-derived cytokine, which is mainly expressed by cells of barrier tissues, and is known to activate Th2 lymphocytes, mast cells, and eosinophils. IL-33 signals through a receptor complex consisting of IL-33-specific receptor ST2 and a co-receptor IL-1RAcP. As IL-33 is known to promote Th2-type immunity, we examined expression profiles of IL-33 and its receptor components in human AD skin, in the murine model of AD, and in various cell models. We found increased expression of IL-33 and ST2 in AD skin after allergen or staphylococcal enterotoxin B (SEB) exposure, as well as in the skin of 22-week-old filaggrin-deficient mice. In addition, skin fibroblasts, HaCaT keratinocytes, primary macrophages, and HUVEC endothelial cells efficiently produced IL-33 in response to the combined stimulation of tumor necrosis factor-α and IFN-γ, which was further enhanced by a mimetic of double-stranded RNA. Finally, the increased expression of IL-33 and ST2 caused by irritant, allergen, or SEB challenge was suppressed by topical tacrolimus treatment. These results suggest an important role for IL-33-ST2 interaction in AD and highlight the fact that bacterial and viral infections may increase the production of IL-33.

Association of serum interleukin-18 and other biomarkers with disease severity in adults with atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory disease of the skin for which there are no reliable biomarkers to assess clinical severity. Serum interleukin-18 (IL-18) levels may be associated with AD severity. To identify putative biomarkers associated with clinical severity in adult AD patients, we enrolled 121 adult AD patients (mean age 35.7 years) and 50 healthy controls (mean age 31.7 years). We compared these groups for blood eosinophils and serum levels of IL-18, thymus and activation-regulated chemokine (TARC), total IgE, and lactate dehydrogenase (LDH). We also determined S. aureus enterotoxin B (SEB) specific IgE levels and the SCORingAD (SCORAD) scores for AD patients. For AD patients, stepwise logistic regression was used to estimate odds ratios (OR) for each biomarker for the likelihood of having AD, and multiple linear regression was used to identify biomarkers associated with SCORAD scores. Compared with healthy controls, adult AD patients had higher levels of IL-18, TARC, total IgE, eosinophils, and LDH. TARC levels had the highest OR for AD occurrence, while the OR for IL-18 was insignificant. Also, IL-18 was not related to the presence of SEB-IgE. Notably, IL-18 levels were significantly associated with SCORAD scores, as were TARC, total IgE, and LDH levels. A panel of biomarkers (IL-18, TARC, total IgE, and LDH) may be more useful to accurately assess clinical severity in adult AD patients.