Presence of IgE antibodies to staphylococcal exotoxins on the skin of patients with atopic dermatitis. Evidence for a new group of allergens

Staphylococcal Exotoxins and Nasal Polyposis: Analysis of Systemic and Local Responses

Background

Staphylococcal exotoxins have been implicated in the pathogenesis of several chronic inflammatory diseases including atopic dermatitis (AD), asthma, and, most recently, chronic rhinosinusitis with nasal polyposis (CRS/NP). In severe AD, these toxins act both as superantigens (SAg), triggering massive T-cell activation, and as conventional allergens, triggering toxin-specific immunoglobulin E (IgE) in the serum. In CRS/NP, evidence for both processes has been reported but it is unclear whether these processes are linked. The aim of this study was to correlate SAg activity as inferred by staphylococcal-specific T-cell receptor (TCR) V-β expansion in the polyp and blood of CRS/NP patients with staphylococcal-specific anti-IgE antibodies in the serum.

Methods

IgE antibodies to staphylococcal exotoxin A (SEA), staphylococcal exotoxin B (SEB), and toxic shock syndrome toxin (TSST) 1 were measured in the serum of 12 individuals with CRS/NP before functional endoscopic sinus surgery. Flow cytometry was used to analyze the SEA, SEB, and TSST-1–specific TCR V-β domains on the T cells from the polyp and blood of these patients.

Results

Serum SEA-, SEB-, and TSST-1-specific IgE antibodies were detected in 0/12 (0%), 6/12 (50.0%), and 9/12 (75%) of CRS/NP patients, respectively. Evidence of SAg effect in the polyp lymphocytes (TCR V-β expansion in both CD4+ and CD8+ subsets) was noted in 7/12 (58.3%) patients. Five of 6 CRS/NP patients had overlapping evidence of a systemic IgE response and TCR V-β expansion, suggestive of exposure to the same exotoxin. No patients had evidence a SAg effect in blood lymphocytes. Nine of 12 subjects also had coexistent asthma.

Conclusion

These results provide evidence for a local SAg effect in 7/12 (58.3%) polyp patients and establish a positive correlation of V-β expansion with the presence of corresponding toxin-specific IgE in the serum.

Presence and Characterization of Sensitization to Staphylococcal Enterotoxins in Patients with Allergic Rhinitis

Exotoxins derived from Staphylococcus aureus appear to be involved in the pathogenesis of allergic diseases, especially atopic dermatitis (AD). However, little is known about sensitization to enterotoxins in cases of respiratory allergies. Because the nasal cavity is a primary site of colonization by S. aureus, we sought to determine the prevalence and role of serum immunoglobulin E (IgE) antibodies against staphylococcal enterotoxin A (SEA) and SEB in patients with allergic rhinitis (AR). The presence of SEA- and SEB-specific IgE was determined in 40 patients with AR and 16 healthy control subjects. In the rhinitis group, nasal symptom score, total serum IgE, sensitization to other inhaled allergens and the presence of sinusitis were determined. Twenty-five percent of patients with AR were sensitized to SEA/SEB whereas 6.3% of controls were sensitized to the toxins. Sensitization to SEB was predominant relative to SEA. There were no significant differences in the severity of nasal symptoms and complications of other allergic diseases including AD and bronchial asthma, between patients with or without sensitization to SEA/SEB. However, patients sensitized to these toxins were likely to show increased total serum IgE and polyvalent sensitization, suggesting that exposure and subsequent sensitization to SEA/SEB may be involved in polyvalent sensitization.

House dust mites as potential carriers for IgE sensitization to bacterial antigens

Background

IgE reactivity to antigens from Gram‐positive and Gram‐negative bacteria is common in patients suffering from respiratory and skin manifestations of allergy, but the routes and mechanisms of sensitization are not fully understood. The analysis of the genome, transcriptome and microbiome of house dust mites (HDM) has shown that Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) species are abundant bacteria within the HDM microbiome. Therefore, our aim was to investigate whether HDM are carriers of bacterial antigens leading to IgE sensitization in patients suffering from atopic dermatitis.

Methods

Plasma samples from patients with AD (n = 179) were analysed for IgE reactivity to a comprehensive panel of microarrayed HDM allergen molecules and to S. aureus and E. coli by IgE immunoblotting. Antibodies specific for S. aureus and E. coli antigens were tested for reactivity to nitrocellulose‐blotted extract from purified HDM bodies, and the IgE‐reactive antigens were detected by IgE immunoblot inhibition experiments. IgE antibodies directed to bacterial antigens in HDM were quantified by IgE ImmunoCAP™ inhibition experiments.

Results

IgE reactivity to bacterial antigens was significantly more frequent in patients with AD sensitized to HDM than in AD patients without HDM sensitization. S. aureus and E. coli antigens were detected in immune‐blotted HDM extract, and the presence of IgE‐reactive antigens in HDM was demonstrated by qualitative and quantitative IgE inhibition experiments.

Conclusion

House dust mites (HDM) may serve as carriers of bacteria responsible for the induction of IgE sensitization to microbial antigens.

Infectious Complications in Atopic Dermatitis

Atopic dermatitis is characterized by the interplay of skin barrier defects with the immune system and skin microbiome that causes patients to be at risk for infectious complications. This article reviews the pathogenesis of atopic dermatitis and the mechanisms through which patients are at risk for infection from bacterial, viral, and fungal pathogens. Although these complications may be managed acutely, prevention of secondary infections depends on a multipronged approach in the maintenance of skin integrity, control of flares, and microbial pathogens.

Skin Colonization by Staphylococcus aureus Precedes the Clinical Diagnosis of Atopic Dermatitis in Infancy

Atopic dermatitis (AD) has a well-established association with skin colonization or infection by Staphylococcus aureus, which can exacerbate the disease. However, a causal relationship between specific changes in skin colonization during the first years of life and AD development still remains unclear. In this prospective birth cohort study, we aimed to characterize the association between skin colonization and AD development in 149 white infants with or without a family history of atopy. We assessed infants clinically and collected axillary and antecubital fossa skin swabs for culture-based analysis at birth and at seven time points over the first 2 years of life. We found that at age 3 months, S. aureus was more prevalent on the skin of infants who developed AD later on. S. aureus prevalence was increased on infants' skin at the time of AD onset and also 2 months before it, when compared with age-matched, unaffected infants. Furthermore, at AD onset, infants testing positive for S. aureus were younger than uncolonized subjects. In conclusion, our results suggest that specific changes in early-life skin colonization may actively contribute to clinical AD onset in infancy.

Atopic dermatitis: immune deviation, barrier dysfunction, IgE autoreactivity and new therapies

Atopic dermatitis (AD) is a chronic or chronically relapsing, eczematous, severely pruritic skin disorder mostly associated with IgE elevation and skin barrier dysfunction due to decreased filaggrin expression. The lesional skin of AD exhibits Th2- and Th22-deviated immune reactions that are progressive during disease chronicity. Th2 and Th22 cytokines further deteriorate the skin barrier by inhibiting filaggrin expression. Some IgEs are reactive to self-antigens. The IgE autoreactivity may precipitate the chronicity of AD. Upon activation of the ORAI1 calcium channel, atopic epidermis releases large amounts of thymic stromal lymphopoietin (TSLP), which initiates the Th2 and Th22 immune response. Th2-derived interleukin-31 and TSLP induce an itch sensation. Taken together, TSLP/Th2/Th22 pathway is a promising target for developing new therapeutics for AD. Enhancing filaggrin expression using ligands for the aryl hydrocarbon receptor may also be an adjunctive measure to restore the disrupted barrier function specifically for AD.

The etiopathogenesis of atopic dermatitis: barrier disruption, immunological derangement, and pruritus

Atopic dermatitis (AD) is a common chronic skin inflammatory disorder characterized by recurrent eczema accompanied by an intractable itch that leads to an impaired quality of life. Extensive recent studies have shed light on the multifaceted pathogenesis of the disease. The complex interplay among skin barrier deficiency, immunological derangement, and pruritus contributes to the development, progression, and chronicity of the disease. Abnormalities in filaggrin, other stratum corneum constituents, and tight junctions induce and/or promote skin inflammation. This inflammation, in turn, can further deteriorate the barrier function by downregulating a myriad of essential barrier-maintaining molecules. Pruritus in AD, which may be due to hyperinnervation of the epidermis, increases pruritogens, and central sensitization compromises the skin integrity and promotes inflammation. There are unmet needs in the treatment of AD. Based on the detailed evidence available to date, certain disease mechanisms can be chosen as treatment targets. Numerous clinical trials of biological agents are currently being conducted and are expected to provide treatments for patients suffering from AD in the future. This review summarizes the etiopathogenesis of the disease and provides a rationale for choosing the novel targeted therapy that will be available in the future.

Guanine nucleotide exchange factor RABGEF1 regulates keratinocyte-intrinsic signaling to maintain skin homeostasis

Epidermal keratinocytes form a structural and immune barrier that is essential for skin homeostasis. However, the mechanisms that regulate epidermal barrier function are incompletely understood. Here we have found that keratinocyte-specific deletion of the gene encoding RAB guanine nucleotide exchange factor 1 (RABGEF1, also known as RABEX-5) severely impairs epidermal barrier function in mice and induces an allergic cutaneous and systemic phenotype. RABGEF1-deficient keratinocytes exhibited aberrant activation of the intrinsic IL-1R/MYD88/NF-κB signaling pathway and MYD88-dependent abnormalities in expression of structural proteins that contribute to skin barrier function. Moreover, ablation of MYD88 signaling in RABGEF1-deficient keratinocytes or deletion of Il1r1 restored skin homeostasis and prevented development of skin inflammation. We further demonstrated that epidermal RABGEF1 expression is reduced in skin lesions of humans diagnosed with either atopic dermatitis or allergic contact dermatitis as well as in an inducible mouse model of allergic dermatitis. Our findings reveal a key role for RABGEF1 in dampening keratinocyte-intrinsic MYD88 signaling and sustaining epidermal barrier function in mice, and suggest that dysregulation of RABGEF1 expression may contribute to epidermal barrier dysfunction in allergic skin disorders in mice and humans. Thus, RABGEF1-mediated regulation of IL-1R/MYD88 signaling might represent a potential therapeutic target.

Linoleic acid salt with ultrapure soft water as an antibacterial combination against dermato-pathogenic Staphylococcus spp

AIMS

Skin colonization of Staphylococcus spp. critically affects the severity of dermatitis in humans and animals. We examined different types of fatty acid salts for their antibacterial activity against Staphylococcus spp. when used in ultrapure soft water (UPSW). We also evaluated their therapeutic effect on a spontaneous canine model of dermatitis.

METHODS AND RESULTS

UPSW, in which Ca(++) and Mg(++) were replaced with Na(+) , was generated using a water softener with cation-exchange resin. Staphylococcus aureus (Staph. aureus), Staphylococcus intermedius (Staph. intermedius), and Staphylococcus pseudintermedius (Staph. pseudintermedius) were incubated with various fatty acid salts in distilled water (DW) or UPSW and the number of bacteria was counted. Among the fatty acids, oleic acid salt and linoleic acid (LA) salt reduced the number of these bacteria. Also, UPSW enhanced the antibacterial effect of LA on Staph. spp. In spontaneously developed itchy dermatitis in companion dogs, shampoo treatment with liquid soap containing 10% LA in UPSW improved skin conditions.

CONCLUSIONS

LA salt showed antibacterial activity against Staph. spp. Treatment with soap containing LA with UPSW reduced clinical conditions in dogs with dermatitis.

SIGNIFICANCE AND IMPACT OF THE STUDY

Because colonization of Staph. spp. on the skin exacerbates dermatitis, the use of LA-containing soap in UPSW may reduce unpleasant clinical symptoms of the skin.

Antibodies and superantibodies in patients with chronic rhinosinusitis with nasal polyps

Background

Chronic rhinosinusitis with nasal polyps is associated with local immunoglobulin hyperproduction and the presence of IgE antibodies against Staphylococcus aureus enterotoxins (SAEs). Aspirin-exacerbated respiratory disease is a severe form of chronic rhinosinusitis with nasal polyps in which nearly all patients express anti-SAEs.

Objectives

We aimed to understand antibodies reactive to SAEs and determine whether they recognize SAEs through their complementarity-determining regions (CDRs) or framework regions.

Methods

Labeled staphylococcal enterotoxin (SE) A, SED, and SEE were used to isolate single SAE-specific B cells from the nasal polyps of 3 patients with aspirin-exacerbated respiratory disease by using fluorescence-activated cell sorting. Recombinant antibodies with “matched” heavy and light chains were cloned as IgG₁, and those of high affinity for specific SAEs, assayed by means of ELISA and surface plasmon resonance, were recloned as IgE and antigen-binding fragments. IgE activities were tested in basophil degranulation assays.

Results

Thirty-seven SAE-specific, IgG- or IgA-expressing B cells were isolated and yielded 6 anti-SAE clones, 2 each for SEA, SED, and SEE. Competition binding assays revealed that the anti-SEE antibodies recognize nonoverlapping epitopes in SEE. Unexpectedly, each anti-SEE mediated SEE-induced basophil degranulation, and IgG₁ or antigen-binding fragments of each anti-SEE enhanced degranulation by the other anti-SEE.

Conclusions

SEEs can activate basophils by simultaneously binding as antigens in the conventional manner to CDRs and as superantigens to framework regions of anti-SEE IgE in anti-SEE IgE-FcεRI complexes. Anti-SEE IgG₁s can enhance the activity of anti-SEE IgEs as conventional antibodies through CDRs or simultaneously as conventional antibodies and as “superantibodies” through CDRs and framework regions to SEEs in SEE–anti-SEE IgE-FcεRI complexes.

The immunopathogenesis of staphylococcal skin infections - A review

Staphylococcus aureus and S. pseudintermedius are the major causes of bacterial skin disease in humans and dogs. These organisms can exist as commensals on the skin, but they can also cause severe or even devastating infections. The immune system has evolved mechanisms to deal with pathogenic microorganisms and has strategies to combat bacteria of this type. What emerges is a delicate "peace" between the opposing sides, but this balance can be disrupted leading to a full blown "war". In the ferocious battle that ensues, both sides attempt to get the upper hand, using strategies that are comparable to those used by modern day armies. In this review article, the complex interactions between the immune system and the organisms are described using such military analogies. The process is described in a sequential manner, starting with the invasion itself, and progressing to the eventual battlezone in which there are heavy casualties on both sides. By the end, the appearance of a simple pustule on the skin surface will take on a whole new meaning.

Innate cell communication kick-starts pathogen-specific immunity

Innate cells are responsible for the rapid recognition of infection and mediate essential mechanisms of pathogen elimination, and also facilitate adaptive immune responses. We review here the numerous intricate interactions among innate cells that initiate protective immunity. The efficient eradication of pathogens depends on the coordinated actions of multiple cells, including innate cells and epithelial cells. Rather than acting as isolated effector cells, innate cells are in constant communication with other responding cells of the immune system, locally and distally. These interactions are critically important for the efficient control of primary infections as well for the development of 'trained' innate cells that facilitate the rapid elimination of homologous or heterologous infections.

Current concepts of severe asthma

The term asthma encompasses a disease spectrum with mild to very severe disease phenotypes whose traditional common characteristic is reversible airflow limitation. Unlike milder disease, severe asthma is poorly controlled by the current standard of care. Ongoing studies using advanced molecular and immunological tools along with improved clinical classification show that severe asthma does not identify a specific patient phenotype, but rather includes patients with constant medical needs, whose pathobiologic and clinical characteristics vary widely. Accordingly, in recent clinical trials, therapies guided by specific patient characteristics have had better outcomes than previous therapies directed to any subject with a diagnosis of severe asthma. However, there are still significant gaps in our understanding of the full scope of this disease that hinder the development of effective treatments for all severe asthmatics. In this Review, we discuss our current state of knowledge regarding severe asthma, highlighting different molecular and immunological pathways that can be targeted for future therapeutic development.

Correlation Between Serum 25-Hydroxyvitamin D and Virulence Genes of Staphylococcus aureus Isolates Colonizing Children with Atopic Dermatitis

The skin of children with atopic dermatitis (AD) is colonized with Staphylococcus aureus more frequently than that of their peers. We investigated the prevalence of skin and nares colonization by S. aureus in children with AD, the virulence genes of the isolates, and their association with allergy, AD severity, and serum vitamin D (25(OH)D). This was an observational, cross-sectional study in a sample of children diagnosed with AD in two settings in Spain. The samples were collected in 2012. Swabs from affected skin and nares were taken for microbiologic culture. The prevalence of S. aureus and presence of 17 staphylococcal virulence genes were studied using polymerase chain reaction. A total of 114 patients with a mean age of 5.7 ± 4.1 (range 3 mos to 14 yrs) were included in the study. Swabs were taken from the skin of 113 individuals with AD and from the nares of 85; 28.3% had S. aureus on the skin, which was significantly associated with positive allergen-specific immunoglobulin E antibodies and higher Scoring Atopic Dermatitis (SCORAD) scores in the multivariate analysis. The presence of virulence factors tsst-1, eta, cna, aur, and sec in cutaneous S. aureus isolates was associated with lower serum levels of 25(OH)D. S. aureus on nasal swabs correlated with its presence on the skin and was associated with lower 25(OH)D levels. In conclusion, S. aureus colonization is associated with allergy and severity in AD, whereas certain virulence genes are associated with lower serum 25(OH)D levels.

Mast cell plasticity and sphingosine-1-phosphate in immunity, inflammation and cancer

Mast cells (MC) are found in all vascularized tissues at homeostasis and, until recently, were viewed only as effector cells of allergic reactions via degranulation, the canonical process through which MC release mediators, including histamine and pre-formed proteases and cytokines such as TNF. Cross-linking of IgE bound to surface high affinity receptors for IgE (FcɛRI) by a specific antigen (Ag) triggers signaling events leading to degranulation. We and others have reported the concomitant production and export of an influential multifaceted sphingolipid mediator, sphingosine-1-phosphate (S1P) transported outside of MC by ATP-binding cassettes (ABC) transporters, i.e., independently of degranulation. Indeed, the MC horizon expanded by the discovery of their unique ability to selectively release mediators depending upon the stimulus and receptors involved. Aside from degranulation and transporter usage, MC are also endowed with piecemeal degranulation, a slower process during which mediator release occurs with minor morphological changes. The broad spectrum of pro- and anti-inflammatory bioactive substances MC produce and release, their amounts and delivery pace render these cells bona fide fine-tuners of the immune response. In this viewpoint article, MC developmental, phenotypic and functional plasticity, its modulation by microRNAs and its relevance to immunity, inflammation and cancer will be discussed.

The role of air pollutants in atopic dermatitis

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease and a growing health concern, especially in children, because of its high prevalence and associated low quality of life. Genetic predisposition, environmental triggers, or interactions between them contribute to the pathophysiology of AD. Therefore, it is very important to identify and control risk factors from the environment in susceptible subjects for successful treatment and prevention. Both indoor and outdoor air pollution, which are of increasing concern with urbanization, are well-known environmental risk factors for asthma, whereas there is relatively little evidence in AD. This review highlights epidemiologic and experimental data on the role of air pollution in patients with AD. Recent evidence suggests that a variety of air pollutants, such as environmental tobacco smoke, volatile organic compounds, formaldehyde, toluene, nitrogen dioxide, and particulate matter, act as risk factors for the development or aggravation of AD. These air pollutants probably induce oxidative stress in the skin, leading to skin barrier dysfunction or immune dysregulation. However, these results are still controversial because of the low number of studies, limitations in study design, inaccurate assessment of exposure and absorption, and many other issues. Further research about the adverse effects of air pollution on AD will help to expand our understanding and to establish a better strategy for the prevention and management of AD.

Commensal bacteria and cutaneous immunity

The skin is the human body's largest organ and is home to a diverse and complex variety of innate and adaptive immune functions that protect against pathogenic invasion. Recent studies have demonstrated that cutaneous commensal bacteria modulated the host immune system. For example, Staphylococcus epidermidis, a skin commensal bacterium, has been demonstrated to induce cutaneous interferon (IFN)-γ- and interleukin (IL)-17A-producing T cells. In addition, cutaneous microbiota changes occur in the chronic inflammatory skin disorders, such as atopic dermatitis, and may influence the activity of skin diseases. In this article, we will review the recent findings related to the interactions of the commensal bacteria with skin homeostasis and discuss the role of the dysbiosis of these bacteria in the pathogenesis of skin diseases.

Association Between PTPN22 Polymorphisms and IgE Responses to Staphylococcal Superantigens in Chronic Urticaria

Protein tyrosine phosphatase-22 (PTPN22) gene encodes lymphoid-specific tyrosine phosphatase (Lyp), an inhibitor of T cell activation. A polymorphism of the PTPN22 gene has been found to be associated with chronic urticaria (CU). We investigated the associations between PTPN22 gene polymorphisms and CU characteristics, including serum specific IgE antibodies response to toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxin A (SEA). CU patients (n=409) and normal healthy controls (n=388) were enrolled in the present study. Serum specific IgE to TSST-1 and SEA were measured by ImmunoCAP®. Five PTPN22 single nucleotide polymorphisms, -1123G>C, 1858C>T, 13145A>G, 14943C>T, and 20628A>G, were genotyped. There were no significant differences in genotype or haplotype frequencies of these polymorphisms between the 2 groups. CU patients carrying the GG genotype at 20628A>G (P=0.035) or haplotype 3 [GGG] (P=0.047) had a significantly higher prevalence of serum specific IgE to TSST-1 compared to non-carriers. Similarly, CT/TT genotype at 14943C>T had a significantly higher prevalence of serum specific IgE to SEA (P=0.045). The findings suggest that the PTPN22 gene polymorphisms at 20628A>G and 14943C>T may enhance serum specific IgE responses to TSST-1 and SEA, which may contribute to CU pathogenesis.

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.

Toxic interaction between Th2 cytokines and Staphylococcus aureus in atopic dermatitis

Patients with atopic dermatitis (AD) are commonly colonized/infected with Staphylococcus aureus, and this bacterium is known to worsen the dermatitis. In this issue, Brauweiler et al. demonstrate a newly discovered mechanism by which Th2 cytokines involved in AD augments the toxicity of the lytic staphylococcal protein alpha toxin. This review presents mechanisms by which Th2 cytokines may interact with S. aureus to the detriment of the dermatitis.

Atopy patch test with Aleuroglyphus ovatus antigen in patients with atopic dermatitis

BACKGROUND

Epicutaneous test made with dust mite antigens.

OBJECTIVE

Evaluation of the response of the epicutaneous test with Aleuroglyphus ovatus antigen in atopic patients.

METHODS

We patch tested 119 individuals, 48 with atopic dermatitis, 50 with respiratory allergy and 21 healthy controls. We compare the positive response frequency to a closed patch test using Aleuroglyphus ovatus antigen in different concentrations and 48 and 96h reading times among those individuals.

RESULTS

Six patients with atopic dermatitis (12.5%) and 4 with respiratory atopy (8.0%) had positive reactions. None of the non-atopic controls had a positive response. As the antigen concentration raised, the number of positive reactions to epicutaneous test raised as well.

CONCLUSION

Our data suggest a positive relation between Atopy Patch Test positive responses and Aleuroglyphus ovatus antigen concentration, no matter the kind of the atopic clinical expression.

Staphylococcal and streptococcal superantigen exotoxins

SUMMARY This review begins with a discussion of the large family of Staphylococcus aureus and beta-hemolytic streptococcal pyrogenic toxin T lymphocyte superantigens from structural and immunobiological perspectives. With this as background, the review then discusses the major known and possible human disease associations with superantigens, including associations with toxic shock syndromes, atopic dermatitis, pneumonia, infective endocarditis, and autoimmune sequelae to streptococcal illnesses. Finally, the review addresses current and possible novel strategies to prevent superantigen production and passive and active immunization strategies.

New insights in the pathogenesis of atopic dermatitis

Atopic dermatitis (AD) is characterized by skin barrier defects and increased interleukin (IL)-4/IL-13 expression. Recent evidence also suggests the involvement of innate immunity including Toll-like receptors, IL-33, IL-25, and innate lymphoid cells in the pathogenesis of AD. This article reviews these innate immune components and how they may become an integral part of prognostic factors and therapeutic targets in the treatment of AD.

The Atopic March: Progression from Atopic Dermatitis to Allergic Rhinitis and Asthma

The development of atopic dermatitis (AD) in infancy and subsequent allergic rhinitis and asthma in later childhood is known as the atopic march. This progressive atopy is dependent on various underlying factors such as the presence of filaggrin mutations as well as the time of onset and severity of AD. Clinical manifestations vary among individuals. Previously it was thought that atopic disorders may be unrelated with sequential development. Recent studies support the idea of a causal link between AD and later onset atopic disorders. These studies suggest that a dysfunctional skin barrier serves as a site for allergic sensitization to antigens and colonization of bacterial super antigens. This induces systemic Th2 immunity that predisposes patients to allergic nasal responses and promotes airway hyper reactivity. While AD often starts early in life and is a chronic condition, new research signifies that there may be an optimal window of time in which targeting the skin barrier with therapeutic interventions may prevent subsequent atopic disorders. In this review we highlight recent studies describing factors important in the development of atopic disorders and new insights in our understanding of the pathogenesis of the atopic march.

Atopic dermatitis and the stratum corneum: part 3: the immune system in atopic dermatitis

Part 3 of this three-part review of atopic dermatitis and the stratum corneum barrier discerns how immune dysregulation, including upregulation of a TH2 inflammation pattern, augmented allergic sensitization, sustained wound healing inflammation, and impaired innate immunity, plays an integral role in the pathogenesis of atopic dermatitis. An increased understanding of the interdependence, polymorphisms, and dysregulations of epidermal barrier functions, including the stratum corneum permeability barrier, immune defense, and antimicrobial barriers, should provide further knowledge about the pathophysiological mechanisms that are clinically relevant and that contribute to the development of atopic dermatitis. Further understanding of these mechanisms should lead to newer therapies that target specific pathogenic components of atopic dermatitis.

Characterization of Bacterium Isolated from the Sediment at Coastal Area of Omura Bay in Japan and Several Biological Activities of Pigment Produced by This Isolate

Recently we discovered a bacterial strain (MS-02-063) that produces large amounts of red pigment from coastal area of Nagasaki Prefecture, Japan. Comparative 16S rDNA gene sequencing analysis revealed that strain MS-02-063 was phylogenetically closely related to gamma-proteobacterium Hahella sp. MBIC 3957 that produces prodigiosin. However, some physiological and biochemical differences between strain MS-02-063 and Hahella sp. MBIC 3957 were observed. The red pigment (RP-063) produced by this isolate was highly purified from the culture supernatant. It was speculated that RP-063 might be prodigiosin-like pigment in physical properties and biological activities such as antibacterial and cytotoxic activity. Antibacterial activity of RP-063 was examined by an agar dilution method. The results indicated that RP-063 showed antibacterial activity for specific for pathogenic gram-positive bacteria such as Staphylococcus aureus. The potency of antibacterial activity against S. aureus was nearly equal to those of tetracycline. Moreover, RP-063 showed inhibition of the superoxide generation by 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated mouse macrophage RAW 264.7 cell line. Prodigiosin members have a wide variety of biological properties, including anticancer and antimalarial, etc. Especially, potent immunosuppressive properties have been reported for prodigiosin members with the mechanism of action different from that of the other well known immunosuppressors in atopic dermatitis therapy such as cyclosporin A, FK506 and rapamycin. It is suggested that RP-063 may be able to arrest the inflammation caused by superantigens secreted from S. aureus, which colonized skin on atopic dermatitis as well as suppression of activated lymphocyte proliferation and superoxide generation from leucocytes.

Lipid abnormalities and lipid-based repair strategies in atopic dermatitis

Prior studies have revealed the key roles played by Th1/Th2 cell dysregulation, IgE production, mast cell hyperactivity, and dendritic cell signaling in the evolution of the chronic, pruritic, inflammatory dermatosis that characterizes atopic dermatitis (AD). We review here increasing evidence that the inflammation in AD results primarily from inherited abnormalities in epidermal structural and enzymatic proteins that impact permeability barrier function. We also will show that the barrier defect can be attributed to a paracellular abnormality due to a variety of abnormalities in lipid composition, transport and extracellular organization. Accordingly, we also review the therapeutic implications of this emerging pathogenic paradigm, including several current and potentially novel, lipid-based approaches to corrective therapy. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Staphylococcus aureus enterotoxin-specific IgE is associated with asthma in the general population: a GA(2)LEN study

BACKGROUND

Specific IgE to Staphylococcus aureus enterotoxins (SE-IgE) has been associated with asthma. In the general population, we aimed to determine the prevalence of and risk factors for serum SE-IgE and to examine the association with asthma.

METHODS

A postal questionnaire was sent to a random sample of adults in 19 centers across Europe. A random sample of respondents was invited for clinical examination upon which they answered a questionnaire, underwent skin prick tests (SPTs) for common aeroallergens, and provided blood for measurement of total IgE and SE-IgE. Risks were analyzed within centers using weighted logistic regression, and overall estimates calculated using fixed-effects meta-analysis.

RESULTS

2908 subjects were included in this analysis. Prevalence of positive SE-IgE was 29.3%; no significant geographic variation was observed. In contrast to positive skin prick tests, SE-IgE was more common in smokers (<15 pack-year: OR 1.11, P = 0.079, ≥15 pack-year: OR 1.70, P < 0.001), and prevalence did not decrease in older age-groups or in those with many siblings. Total IgE concentrations were higher in those with positive SE-IgE than in those with positive SPT. SE-IgE was associated with asthma (OR 2.10, 95% confidence interval [1.60-2.76], P = 0.001) in a concentration-dependent manner. This effect was independent of SPT result and homogeneous across all centers.

CONCLUSIONS

We report for the first time that SE-IgE is common in the general population throughout Europe and that its risk factors differ from those of IgE against aeroallergens. This is the first study to show that SE-IgE is significantly and independently associated with asthma in the general population.

Atopic dermatitis: a practice parameter update 2012

This parameter was developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma and Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Atopic dermatitis: a practice parameter update 2012." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion. Published practice parameters of the Joint Task Force on Practice Parameters for Allergy & Immunology are available online at http://www.jcaai.org.

The multifunctional role of filaggrin in allergic skin disease

Filaggrin is a major structural protein in the stratum corneum of the epidermis. Mutations in the filaggrin gene are the most significant known genetic risk factor for the development of atopic dermatitis. Mutations in the human filaggrin gene (FLG) also confer risk for the associated allergic diseases of food allergy, asthma, and allergic rhinitis. These discoveries have highlighted the importance of skin barrier function in the pathogenesis of atopic diseases and have motivated a surge in research characterizing the filaggrin-deficient skin barrier and its consequences. In this review we discuss the mechanisms through which mutations in this protein contribute to the pathogenesis of atopic dermatitis and associated atopic conditions. We focus on recent human and murine discoveries characterizing the filaggrin-deficient epidermis with respect to biophysical, immunologic, and microbiome abnormalities.

Role of staphylococcal superantigens in airway disease

Staphylococcus aureus is a common human pathogen, which is regularly part of the normal microflora found in the nose and skin. It represents a significant threat to human health, not in the least because of its capability to produce exotoxins, which have superantigenic properties. These exotoxins, in particular the staphylococcal enterotoxins (SEs), are known to be involved in the modulation and aggravation of airway inflammation. Indeed, recent studies show an important impact of SEs on the natural course of allergic rhinitis, nasal polyposis, asthma and COPD. This review outlines the current knowledge on the influence of SEs on airway inflammation. We highlight, in particular, the recent evidence on their role in asthma.

Development and evaluation of colloidal modified nanolipid carrier: application to topical delivery of tacrolimus, Part II--in vivo assessment, drug targeting, efficacy, and safety in treatment for atopic dermatitis

In atopic dermatitis (AD), topical anti-inflammatory therapy with skin barrier restoration to prevent repeated inflammatory episodes leads to long-term therapeutic success. Tacrolimus, although effective against AD, is a challenging molecule due to low solubility, low-penetration, poor-bioavailability, and toxicity. Part I of this paper, reported novel modified nanolipid carrier system for topical delivery of tacrolimus (T-MNLC), offering great opportunity to load low-solubility drug with improved entrapment efficiency, enhanced stability and improved skin deposition. Present investigation focused on restoration of skin barrier, site-specific delivery, therapeutic effectiveness, and safety of novel T-MNLC. T-MNLC greatly enhanced occlusive properties, skin hydration potential and reduced transepidermal water loss. This might help to reduce the number of flares and better control the disease. Cutaneous uptake and drug deposition in albino rats by HPLC and confocal laser scanning microscopy revealed prominently elevated drug levels in all skin strata with T-MNLC as compared to reference. T-MNLC demonstrated efficient suppression of inflammatory responses in BALB/c mice model of AD. Safety assessment by acute and repeated-dose dermal toxicity demonstrated mild keratosis and collagenous mass infiltration at the treatment area with repeated application of reference. Interestingly, T-MNLC showed no evident toxicity exhibiting safe drug delivery. Thus, novel T-MNLC would be a safe, effective, and esthetically appealing alternative to conventional vehicles for treatment for AD.

Analysis of Colonization and Genotyping of the Exotoxins of Staphylococcus aureus in Patients with Atopic Dermatitis

BACKGROUND

The skin of atopic dermatitis (AD) patients has a high susceptibility to Staphylococcus aureus colonization, and the toxins produced by S. aureus may aggravate AD by acting as superantigens.

OBJECTIVE

The purpose of this study was to evaluate the relationship of the skin barrier function, colonization of S. aureus, and the clinical severity of AD. We also examined the predominant toxin genes produced in Korean AD patients.

METHODS

Thirty-nine patients with AD were evaluated for clinical severity and skin barrier function by using Severity Scoring of Atopic Dermatitis (SCORAD) index and transepidermal water loss (TEWL). S. aureus was isolated from the forearm, popliteal fossa, and anterior nares of AD patients (n=39) and age-matched controls (n=40); the toxin genes were analyzed by performing multiplex polymerase chain reaction.

RESULTS

TEWL showed a statistically significant correlation with clinical severity in patients with AD (p<0.05). TEWL was correlated with the number of S. aureus colonization sites and the presence of nasal colonization, but these results were not statistically significant. S. aureus strains were isolated in 64.1% of the 39 AD patients. The SCORAD index and AD severity were strongly correlated with the number of colonization sites. The predominant toxin gene found in AD patients was staphylococcal enterotoxin a (sea) only, which was produced in 52.6% of patients. The toxin genes sea and toxic shock syndrome toxin-1 (tsst-1) were found together in 42.1%, while tsst-1 only was found in 5.3% of the patients.

CONCLUSION

S. aureus strains were isolated in 64.1% of the 39 AD patients. Skin barrier function, as measured by TEWL, revealed a statistically significant correlation with clinical severity in AD patients. The SCORAD index and severity of AD was strongly correlated with the number of colonization. The most common toxin gene was sea in the Korean AD patients and this gene might have an important role in the pathogenesis of AD.

Combined external therapy of atopic dermatitis complicated with a secondary infection

The authors discuss the reasons of the violation of the skin barrier in patients suffering from atopic dermatitis and determine the role of pyococcus, dermatomycetes and yeast-like fungi in the development of this disease. They also describe the reasons of failures of the external therapy of atopic dermatitis with the use of combined drugs containing antibiotics. The authors substantiate the possibility of using the Travocort cream in case the disease is complicated with a secondary infection. They also describe their own study of the treatment of eczema herpeticum when the Travocort cream was included in the external therapy.