Epicutaneous exposure to staphylococcal superantigen enterotoxin B enhances allergic lung inflammation via an IL-17A dependent mechanism

The role of the skin microbiome in wound healing

The efficient management of skin wounds for rapid and scarless healing represents a major clinical unmet need. Nonhealing skin wounds and undesired scar formation impair quality of life and result in high healthcare expenditure worldwide. The skin-colonizing microbiota contributes to maintaining an intact skin barrier in homeostasis, but it also participates in the pathogenesis of many skin disorders, including aberrant wound healing, in many respects. This review focuses on the composition of the skin microbiome in cutaneous wounds of different types (i.e. acute and chronic) and with different outcomes (i.e. nonhealing and hypertrophic scarring), mainly based on next-generation sequencing analyses; furthermore, we discuss the mechanistic insights into host-microbe and microbe-microbe interactions during wound healing. Finally, we highlight potential therapeutic strategies that target the skin microbiome to improve healing outcomes.

Phenotype overlap in the natural history of asthma

The heterogeneity of asthma makes it challenging to unravel the pathophysiologic mechanisms of the disease. Despite the wealth of research identifying diverse phenotypes, many gaps still remain in our knowledge of the disease's complexity. A crucial aspect is the impact of airborne factors over a lifetime, which often results in a complex overlap of phenotypes associated with type 2 (T2), non-T2 and mixed inflammation. Evidence now shows overlaps between the phenotypes associated with T2, non-T2 and mixed T2/non-T2 inflammation. These interconnections could be induced by different determinants such as recurrent infections, environmental factors, T-helper plasticity and comorbidities, collectively resulting in a complex network of distinct pathways generally considered as mutually exclusive. In this scenario, we need to abandon the concept of asthma as a disease characterised by distinct traits grouped into static segregated categories. It is now evident that there are multiple interplays between the various physiologic, cellular and molecular features of asthma, and the overlap of phenotypes cannot be ignored.

NOD2 Agonism Counter-Regulates Human Type 2 T Cell Functions in Peripheral Blood Mononuclear Cell Cultures: Implications for Atopic Dermatitis

Atopic dermatitis (AD) is known as a skin disease; however, T cell immunopathology found in blood is associated with its severity. Skin Staphylococcus aureus (S. aureus) and associated host-pathogen dynamics are important to chronic T helper 2 (Th2)-dominated inflammation in AD, yet they remain poorly understood. This study sought to investigate the effects of S. aureus-derived molecules and skin alarmins on human peripheral blood mononuclear cells, specifically testing Th2-type cells, cytokines, and chemokines known to be associated with AD. We first show that six significantly elevated Th2-related chemokine biomarkers distinguish blood from adult AD patients compared to healthy controls ex vivo; in addition, TARC/CCL17, LDH, and PDGF-AA/AB correlated significantly with disease severity. We then demonstrate that these robust AD-associated biomarkers, as well as associated type 2 T cell functions, are readily reproduced from healthy blood mononuclear cells exposed to the alarmin TSLP and the S. aureus superantigen SEB in a human in vitro model, including IL-13, IL-5, and TARC secretion as well as OX-40-expressing activated memory T cells. We further show that the agonism of nucleotide-binding oligomerization domain-containing protein (NOD)2 inhibits this IL-13 secretion and memory Th2 and Tc2 cell functional activation while inducing significantly increased pSTAT3 and IL-6, both critical for Th17 cell responses. These findings identify NOD2 as a potential regulator of type 2 immune responses in humans and highlight its role as an endogenous inhibitor of pathogenic IL-13 that may open avenues for its therapeutic targeting in AD.

The Role of Staphylococcus aureus and Its Toxins in the Pathogenesis of Allergic Asthma

Bronchial asthma is one of the most common chronic diseases worldwide and affects more than 300 million patients. Allergic asthma affects the majority of asthmatic children as well as approximately 50% of adult asthmatics. It is characterized by a Th2-mediated immune response against aeroallergens. Many aspects of the overall pathophysiology are known, while the underlying mechanisms and predisposing factors remain largely elusive today. Over the last decade, respiratory colonization with Staphylococcus aureus (S. aureus), a Gram-positive facultative bacterial pathogen, came into focus as a risk factor for the development of atopic respiratory diseases. More than 30% of the world’s population is constantly colonized with S. aureus in their nasopharynx. This colonization is mostly asymptomatic, but in immunocompromised patients, it can lead to serious complications including pneumonia, sepsis, or even death. S. aureus is known for its ability to produce a wide range of proteins including toxins, serine-protease-like proteins, and protein A. In this review, we provide an overview of the current knowledge about the pathophysiology of allergic asthma and to what extent it can be affected by different toxins produced by S. aureus. Intensifying this knowledge might lead to new preventive strategies for atopic respiratory diseases.

New Directions in Understanding Atopic March Starting from Atopic Dermatitis

Recent evidence showed that the postulated linear progression of the atopic march, from atopic dermatitis to food and respiratory allergies, does not capture the heterogeneity of allergic phenotypes, which are influenced by complex interactions between environmental, genetic, and psychosocial factors. Indeed, multiple atopic trajectories are possible in addition to the classic atopic march. Nevertheless, atopic dermatitis is often the first manifestation of an atopic march. Improved understanding of atopic dermatitis pathogenesis is warranted as this could represent a turning point in the prevention of atopic march. In this review, we outline the recent findings on the pathogenetic mechanisms leading to atopic dermatitis that could be targeted by intervention strategies for the prevention of atopic march.

Modulation of Allergic Sensitization and Allergic Inflammation by Staphylococcus aureus Enterotoxin B in an Ovalbumin Mouse Model

The superantigen Staphylococcus aureus (S. aureus) enterotoxin B (SEB) has been proposed a central player in the associations between S. aureus nasal colonization and the development of allergic asthma. Previously, SEB has been shown to aggravate allergic sensitization and allergic airway inflammation (AAI) in experimental mouse models. Aiming at understanding the underlying immunological mechanisms, we tested the hypothesis that intranasal (i.n.) SEB-treatment divergently modulates AAI depending on the timing and intensity of the SEB-encounter. In an ovalbumin-mediated mouse model of AAI, we treated mice i.n. with 50 ng or 500 ng SEB either together with the allergic challenge or prior to the peripheral sensitization. We observed SEB to affect different hallmark parameters of AAI depending on the timing and the dose of treatment. SEB administered i.n. together with the allergic challenge significantly modulated respiratory leukocyte accumulation, intensified lymphocyte activation and, at the higher dose, induced a strong type-1 and pro-inflammatory cytokine response and alleviated airway hyperreactivity in AAI. SEB administered i.n. prior to the allergic sensitization at the lower dose significantly boosted the specific IgE response while administration of the higher dose led to a significantly reduced recruitment of immune cells, including eosinophils, to the respiratory tract and to a significantly dampened Th-2 cytokine response without inducing a Th-1 or pro-inflammatory response. We show a remarkably versatile potential for SEB to either aggravate or alleviate different parameters of allergic sensitization and AAI. Our study thereby not only highlights the complexity of the associations between S. aureus and allergic asthma but possibly even points at prophylactic and therapeutic pathways.

Staphylococcus Aureus in chronic airway diseases: An overview

This review investigates about the role of Staphylococcus Aureus (S. aureus) and S. aureus enterotoxins (SEs) in the pathogenesis of several chronic airway diseases. S. aureus is part of normal human flora and may colonize the skin and the upper airways. SEs acting as superantigens can induce an intense T cell activation and through the release of interleukin (IL) - 4, 5, and 13, can promote a polyclonal IgE response and eosinophilic inflammation. S. aureus can damage epithelial cells inducing the release of the so-called "alarmins" responsible of the activation of Type 2 innate lymphoid cells (ILC-2) linked to an IL-5 mediated airway eosinophilic inflammation. SEs sensitization has been recently associated with the eosinophilic endotypes of both nasal polyps and late onset severe asthma. Studies investigating the effect of biological therapies in SEs sensitized patients should be performed in order to better define the role played by S. aureus in the different endotypes of severe asthma and/or chronic rhinosinusitis.

Epicutaneous Exposure to Peanut Oil Induces Systemic and Pulmonary Allergic Reaction in Mice

BACKGROUND

The prevalence of peanut allergy (PA) is constantly on the rise. Atopic dermatitis (AD) is a major risk factor for developing food allergy. Some bath oils and skin creams used for treating AD contain peanut oil, and it has been suggested that exposure to peanut allergens through a disrupted skin barrier is a potential cause of PA. Our aim was to investigate whether application of peanut oil to irritated skin causes a systemic or respiratory allergic response to peanuts in an animal model.

METHODS

BALB/c mice underwent epicutaneous sensitization with either peanut oil (PM, n = 9) or phosphate buffered solution (controls, n = 9) daily for 5 consecutive days. Ten days after the last exposure the mice were challenged with intranasal peanut protein for 5 consecutive days. Bronchial alveolar lavage fluid was collected for cellular studies and measurement of cytokine levels. Sera were collected for immunoglobulin E (IgE) measurement.

RESULTS

Epicutaneous peanut oil sensitization increased leukocyte and eosinophil counts and interleukin-13 levels (p = 0.003, p = 0.0006 and p = 0.03, respectively), in addition to increasing total serum IgE (p = 0.03).

CONCLUSIONS

The results suggest that topical application of peanut oil may play a role in the etiology of PA.

IL-22 promotes allergic airway inflammation in epicutaneously sensitized mice

BACKGROUND

Serum IL-22 levels are increased in patients with atopic dermatitis, which commonly precedes asthma in the atopic march. Epicutaneous sensitization in mice results in TH2-dominated skin inflammation that mimics atopic dermatitis and sensitizes the airways for antigen challenge-induced allergic inflammation characterized by the presence of both eosinophils and neutrophils. Epicutaneous sensitization results in increased serum levels of IL-22.

OBJECTIVE

We sought to determine the role of IL-22 in antigen-driven airway allergic inflammation after inhalation challenge in epicutaneously sensitized mice.

METHODS

Wild-type (WT) and Il22-/- mice were sensitized epicutaneously or immunized intraperitoneally with ovalbumin (OVA) and challenged intranasally with antigen. OVA T-cell receptor-specific T cells were TH22 polarized in vitro. Airway inflammation, mRNA levels in the lungs, and airway hyperresponsiveness (AHR) were examined.

RESULTS

Epicutaneous sensitization preferentially elicited an IL-22 response compared with intraperitoneal immunization. Intranasal challenge of mice epicutaneously sensitized with OVA elicited in the lungs Il22 mRNA expression, IL-22 production, and accumulation of CD3+CD4+IL-22+ T cells that coexpressed IL-17A and TNF-α. Epicutaneously sensitized Il22-/- mice exhibited diminished eosinophil and neutrophil airway infiltration and decreased AHR after intranasal OVA challenge. Production of IL-13, IL-17A, and TNF-α was normal, but IFN-γ production was increased in lung cells from airway-challenged and epicutaneously sensitized Il22-/- mice. Intranasal instillation of IFN-γ-neutralizing antibody partially reversed the defect in eosinophil recruitment. WT recipients of TH22-polarized WT, but not IL-22-deficient, T-cell receptor OVA-specific T cells, which secrete both IL-17A and TNF-α, had neutrophil-dominated airway inflammation and AHR on intranasal OVA challenge. Intranasal instillation of IL-22 with TNF-α, but not IL-17A, elicited neutrophil-dominated airway inflammation and AHR in WT mice, suggesting that loss of IL-22 synergy with TNF-α contributed to defective recruitment of neutrophils into the airways of Il22-/- mice. TNF-α, but not IL-22, blockade at the time of antigen inhalation challenge inhibited airway inflammation in epicutaneously sensitized mice.

CONCLUSION

Epicutaneous sensitization promotes generation of antigen-specific IL-22-producing T cells that promote airway inflammation and AHR after antigen challenge, suggesting that IL-22 plays an important role in the atopic march.

Interactions Between Atopic Dermatitis and Staphylococcus aureus Infection: Clinical Implications

Staphylococcus aureus commonly colonizes the skin of atopic dermatitis (AD) patients and contributes to the development and exacerbation of AD. Multiple factors are associated with colonization of AD skin by S. aureus, including the strength of S. aureus-corneocyte adhesion, deficiency of antimicrobial peptides, decreased levels of filaggrin and filaggrin degradation products, overexpressed Th2/Th17 cytokines, microbial dysbiosis and altered lipid profiles. S. aureus colonization on AD skin causes skin barrier dysfunction through virulence factors such as superantigens (toxins), enzymes and other proteins. Furthermore, colonization of AD skin by S. aureus exacerbates AD and may contribute to microbial dysbiosis, allergen sensitization, Th2/Th17 polarization, development of atopic march and food allergy in AD patients. Skin colonization of S. aureus, particularly methicillin-resistant S. aureus (MRSA), is one of the major challenges commonly encountered in the management of AD. Bleach bath, and topical or systemic antibiotics could be used to control S. aureus infection on AD skin. However, careful use of antibiotics is required to control the occurence of MRSA. Recently, various strategies, including microbiome transplant, monoclonal antibodies against virulent toxins, vaccines and recombinant phage endolysin, have been studied to control S. aureus infection on AD skin. Further advances in our understanding of S. aureus could provide us with ways to manage S. aureus colonization more effectively in AD patients.

Glucocorticoid insensitivity by staphylococcal enterotoxin B in keratinocytes of allergic dermatitis is associated with impaired nuclear translocation of the Glucocorticoid Receptor α

BACKGROUND

staphylococcal enterotoxin plays an important role in patients with glucocorticoid (GC)-resistant atopic dermatitis (AD), but the exact mechanism is not fully understood.

OBJECTIVE

The aim of this study was to investigate the mechanisms underlying the ability of staphylococcal enterotoxin B (SEB) to induce steroid insensitivity through impaired nuclear translocation of GRα in keratinocytes.

METHODS

The steroid-resistant AD induced by SEB was assessed by analyzing dermatitis score, dermal thickness, scratching behavior, infiltrating cells/HPF, levels of SEB-specific IgE and IgG2a antibody. In addition, dexamethasone (DEX)-induced GRα nuclear translocation and keratinocyte-derived cytokines and chemokines were analyzed in the lesional keratinocytes of AD and in HaCaT cells. Furthermore, the expressions of immunophilins FKBP51, FKBP52 and HSP90 responsive to GC in HaCaT cells were determined in the presence of SEB.

RESULTS

SEB dose-dependently diminished the inhibitory effect of DEX on dermatitis score, dermal thickness, scratching behavior, infiltrating cells/HPF, keratinocyte-derived cytokines and chemokines such as RANTES, MCP-1, TSLP and GM-CSF. In vivo and in vitro data showed that in the presence of DEX, SEB dose-dependently caused a marked decrease of GRα nuclear translocation in lesional keratinocytes of AD and in HaCaT cells. Importantly, in the presence of DEX, SEB increased the expression of FKBP51 and the product of keratinocyte-derived cytokines and chemokines in HaCaT cells.

CONCLUSION

These results demonstrate that GC insensitivity by SEB in keratinocytes of AD is associated with impaired nuclear translocation of the GRα. Increased DEX-induced FKBP51 by SEB may contribute to accumulation of the GRα in cytoplasm of keratinocytes.

New insights into the phenotypes of atopic dermatitis linked with allergies and asthma in children: An overview

Atopic dermatitis (AD) is a complex disease with multiple causes and complex mechanistic pathways according to age of onset, severity of the illness, ethnic modifiers, response to therapy and triggers. A group of difficult-to-manage patients characterized by early-onset AD and severe lifelong disease associated with allergic asthma and/or food allergy (FA) has been identified. In this study, we focus on these severe phenotypes, analysing their links with other atopic comorbidities, and taking into account the results from recent cohort studies and meta-analyses. The main hypothesis that is currently proposed to explain the onset of allergic diseases is an epithelial barrier defect. Thus, the atopic march could correspond to an epithelial dysfunction, self-sustained by a secondary allergenic sensitization, explaining the transition from AD to allergic asthma. Furthermore, AD severity seems to be a risk factor for associated FA. Results from population-based, birth and patient cohorts show that early-onset and severe AD, male gender, parental history of asthma, and early and multiple sensitizations are risk factors leading to the atopic march and the development of asthma. The importance of environmental factors should be recognized in these high-risk children and prevention programs adapted accordingly. Effective targeted therapies to restore both barrier function and to control inflammation are necessary; early emollient therapy is an important approach to prevent AD in high-risk children. Clinicians should also keep in mind the specific risk of atopic comorbidities in case of filaggrin loss-of-function mutations and the rare phenotypes of orphan syndromes due to heritable mutations in skin barrier components.

Inhibition of fracture healing in the presence of contamination by Staphylococcus aureus: Effects of growth state and immune response

Extremity injuries comprise a significant portion of trauma, affecting quality of life, financial burden, and return to duty. Bacterial contamination is commonly associated with failure to heal, despite antibiotic treatment, suggesting that additional therapies must be developed to combat these complications. Treatment failure is likely due to the presence of resistant microbial communities known as biofilms. Biofilm bacteria are able to elicit a direct inhibition of healing through a multitude of known factors. However, they likely also inhibit healing through alteration of the inflammatory response. As inflammation is a critical step in fracture healing, how the presence of biofilm bacteria shifts this response to one that is suboptimal for healing is an important consideration that is currently understudied. The profile of inflammatory factors in response to biofilm bacteria is unique and distinct from those induced during normal healing or by planktonic bacteria alone. This review will examine the presence of inflammatory factors during normal healing and those induced by contaminating bacteria, and will discuss how these differences may ultimately lead to nonunion. Specifically, this review will focus on the Th1/Th2/Th17 type inflammatory responses and how shifts in the balance of these responses during infection can lead to both ineffective clearance and disruption of fracture healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1845-1854, 2017.

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

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

Impaired Toll-like receptor 2-mediated Th1 and Th17/22 cytokines secretion in human peripheral blood mononuclear cells from patients with atopic dermatitis

BACKGROUND

Impaired Toll-like receptor 2 (TLR2) function has been associated with the pathogenesis of atopic dermatitis (AD). However, there are only few studies reporting on the TLR2-induced immunological responses of circulating leucocytes of AD patients. We thus investigated the expression and secretion of Th1, Th2 and Th17/22 cytokines triggered by TLR2 ligands in human peripheral blood mononuclear cells (PBMCs) from AD patients. Expression of TLR2, 1, 6 and high-affinity receptor for IgE (FcεRI) were further investigated to evaluate the outcome of immune response in AD.

METHODS

Expression of TLR2, 1, 6 and FcεRI in PBMCs from AD patients and healthy individuals were measured by qPCR. Subsequent to stimulation with TLR2 ligands PGN and Pam3CSK4, expression and secretion of Th1, Th2 and Th17/22 cytokines were investigated by qPCR and ELISA.

RESULTS

The levels of TLR2, 1, 6 mRNA were not altered in both groups of subjects while that of FcεRI was increased in AD patients. Subsequent to the activation by TLR2 ligands, PBMCs from AD patients significantly released less IFN-γ, IL-17F and IL-22 than those from healthy controls while no detectable level of release was observed with the other cytokines. In contrast, significantly higher levels of mRNA expression for TNF-α, IL5, IL-17A and IL-22 were observed in TLR2 activated PBMCs of AD patients than those of healthy control.

CONCLUSIONS

PBMCs from AD patients are defective in the secretion of Th1 and Th17/22 cytokines in response to TLR2 ligands. The inconsistent increased expression of the mRNA for the corresponding Th1 cytokines and the Th2 cytokines IL-5 suggested that there may be alterations of downstream signaling events in the cytokine release mechanisms of PBMCs that are associated with the development of AD.

Th17 response and its regulation in inflammatory upper airway diseases

Allergic rhinitis (AR) and chronic rhinosinusitis (CRS) are two widely prevalent inflammatory diseases in the upper airways. T cell immunity has been suggested to play an important pathogenic role in many chronic inflammatory diseases including inflammatory upper airway diseases. Inappropriate CD4(+) T cell responses, especially the dysregulation of the Th1/Th2 balance leading to excessive Th1 or Th2 cell activation, have been associated with allergic rhinitis and chronic rhinosinusitis. Nevertheless, recent studies suggest that IL-17A and IL-17A-producing Th17 cell subset, a distinct pro-inflammatory CD4(+) T cell lineage, may also play an important role in the pathophysiology of inflammatory upper airway diseases. Th17 cells may promote both eosinophilic and neutrophilic inflammation in AR and CRS. In addition, a few, but accumulating evidence shows that the Th17 responses can be tightly regulated by endogenous and exogenous substances in the context of AR and CRS. This review discusses recent advances in our understanding of the expression and function of the Th17 response and its regulation in inflammatory upper airway diseases, and the perspective for future investigation and clinical utility.

Allergen-Specific Immunotherapy with Monomeric Allergoid in a Mouse Model of Atopic Dermatitis

Atopic dermatitis (AD) is a widespread and difficult to treat allergic skin disease and is a tough challenge for healthcare. In this study, we investigated whether allergen-specific immunotherapy (ASIT) with a monomeric allergoid obtained by succinylation of ovalbumin (sOVA) is effective in a mouse model of atopic dermatitis. An experimental model of AD was reproduced by epicutaneous sensitization with ovalbumin (OVA). ASIT was performed with subcutaneous (SC) administration of increasing doses of OVA or sOVA. The levels of anti-OVA antibodies, as well as cytokines, were detected by ELISA. Skin samples from patch areas were taken for histologic examination. ASIT with either OVA or sOVA resulted in a reduction of both the anti-OVA IgE level and the IgG1/IgG2a ratio. Moreover, ASIT with sOVA increased the IFN-γ level in supernatants after splenocyte stimulation with OVA. Histologic analysis of skin samples from the sites of allergen application showed that ASIT improved the histologic picture by decreasing allergic inflammation in comparison with untreated mice. These data suggest that ASIT with a succinylated allergen represents promising approach for the treatment of AD.

Interleukin-17A-induced inflammation does not influence the development of nasal polyps in murine model

BACKGROUND

Nasal polyposis associated with chronic rhinosinusitis (CRS) is a chronic inflammatory disease that is characterized by infiltration of many inflammatory cells. Meanwhile, interleukin (IL)-17A is a well-known proinflammatory cytokine that induces both eosinophilic and neutrophilic inflammation. We investigated the role of IL-17A in the development of nasal polyps in the CRS murine model.

METHODS

Eosinophilic CRS with nasal polyps was induced by using ovalbumin (OVA) and Staphylococcus aureus enterotoxin B (SEB) in wild-type BALB/c and IL-17A knockout (KO) mice. Histopathologic changes of the sinonasal cavity were evaluated using hematoxylin and eosin, Periodic acid-Schiff, Sirius red, Masson's trichrome, and immunohistochemistry. The levels of total and OVA-specific immunoglobulin Es (IgEs) in sera were measured using enzyme-linked immunosorbent assay. The expression levels of IL-4, IL-5, and interferon-γ (IFN-γ) in the nasal mucosa were assessed by quantitative real-time polymerase chain reaction.

RESULTS

Under the IL-17A deficiency, total and OVA-specific IgEs in sera were reduced significantly. Infiltration of both eosinophils and neutrophils into the nasal mucosa, subepithelial fibrosis, and goblet cell count also decreased significantly in IL-17A KO mice treated with both OVA and SEB compared with those in the wild-type counterpart. However, there were no significant differences in the number of polypoid lesions among groups. Meanwhile, IL-4 increased and IFN-γ decreased in the nasal mucosa in IL-17A KO mice treated with both OVA and SEB.

CONCLUSION

This study suggests that even though IL-17A plays an important role in both nasal inflammation and remodeling, it does not influence the development of nasal polypoid lesions.

Effects of Lactobacillus rhamnosus on allergic march model by suppressing Th2, Th17, and TSLP responses via CD4(+)CD25(+)Foxp3(+) Tregs

Allergic march (AM) is characterized by the progression of clinical signs of atopic dermatitis (AD) to allergic asthma or rhinitis, but its pathogenesis is not completely understood. We developed mouse model of AM with three 1-week exposures (separated by 2-week interval) to an OVA or saline (control) followed by OVA challenge. The development of AM was confirmed by phenotypes of AD and allergic asthma. Increases in IL-4, IL-17, and thymic stromal lymphopoietin (TSLP) responses were associated with the progression of AM, and these responses were suppressed by treatment with Lcr35. Moreover, Lcr35 treatment led to an increase in the number of CD4(+)CD25(+) Foxp3(+) regulatory T (Treg) cells in the mesenteric lymph nodes (MLNs) of AM mice. In conclusion, the oral application of Lcr35 prevented the development of AM in this model by suppressing Th2, Th17, and TSLP responses via a mechanism that may involve CD4(+)CD25(+)Foxp3(+) Tregs in MLNs.

Shared genetic determinants between eczema and other immune-related diseases

PURPOSE OF REVIEW

Eczema and other allergic disorders are complex diseases caused by multiple genetic and environmental factors. Here, we review recent success in the identification of novel susceptibility loci for eczema.

RECENT FINDINGS

Genome-wide association studies led to marked progress in unraveling the genetic determinants of allergic disorders. In the past 4 years, a total of 14 new eczema susceptibility loci have been identified and nearly all of them were successfully replicated. Seven additional eczema loci were recently identified by alternative strategies utilizing the remarkable overlap in the genetic cause of diverse immune-related traits. Apart from underlining the importance of the skin barrier in eczema, these studies point to specific immunological functions altered in eczema pathogenesis.

SUMMARY

The new findings demonstrate that common pathways are involved in the development of eczema and other immune-related traits. Moreover, the genetic determinants shared between eczema, asthma, and allergic rhinitis should aid in resolving the molecular mechanisms triggering disease progression along the atopic march. The identification of the underlying genes and causal variants will be the major challenge for upcoming studies.

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.

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.

Staphylococcal enterotoxin specific IgE and asthma: a systematic review and meta-analysis

BACKGROUND

Recent literature suggests that Staphylococcal enterotoxin specific IgE may be a risk factor for asthma.

OBJECTIVE

To investigate the associations between Staphylococcal enterotoxin sensitization and asthma.

METHODS

A systematic review and meta-analysis was performed for relevant case-control or population-based studies, published in the peer-reviewed journals until February 2013. Data were extracted on study designs, subjects, definitions and the prevalence of Staphylococcal enterotoxin sensitization.

RESULTS

A total of 683 studies were initially identified, of which 7 studies finally met the inclusion criteria (5 case-control and 2 population-based studies). All the included studies reported higher prevalence of the sensitization in asthmatics than in controls, despite clinical and methodological heterogeneity. In a meta-analysis, the pooled odds ratio of the sensitization for asthma was 2.95 (95% confidence intervals 2.28-3.82).

CONCLUSION

Staphylococcal enterotoxin sensitization was significantly associated with asthma. The mechanisms of associations warrant further elucidation.