Skin thymic stromal lymphopoietin promotes airway sensitization to inhalant house dust mites leading to allergic asthma in mice

Papain Suppresses Atopic Skin Inflammation through Anti-Inflammatory Activities Using In Vitro and In Vivo Models

Papain (PN) is a proteolytic enzyme derived from Carica Papaya L. While the pharmacological effects of PN have not been extensively studied compared to its enzymatic activity, PN also holds potential benefits beyond protein digestion. This study aimed to investigate the potential effects of PN against skin inflammation in house dust mite Dermatophagoides farinae body (Dfb)-exposed NC/Nga atopic dermatitis (AD) mice and human HaCaT keratinocytes and their underlying mechanisms. The effects of PN on the skin were assessed via histological examination, measurements of transepidermal water loss (TEWL), quantitative reverse transcription-polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay. Our findings indicated that the oral intake of PN decreased the severity scores of lesions resembling AD, TEWL, and the levels of inflammatory cytokines and serum immunoglobulin E in Dfb-induced AD mice, along with a reduction in epidermal thickness and mast cell infiltration. Additionally, PN inhibited the activation of the mitogen-activated protein kinases (MAPKs) and the signal transducer and activator of transcription (STAT) pathways in Dfb-induced AD mice and HaCaT keratinocytes. Moreover, PN improved survival and reduced ROS production in H2O2-damaged HaCaT keratinocytes and enhanced the expression of antioxidant enzymes in Dfb-induced AD mice. Concludingly, the oral administration of PN suppressed inflammatory mediators and downregulated the MAPKs/STAT pathway, suggesting its potential role in AD pathogenesis.

Association between interleukin-6-174G/C gene polymorphism and asthma severity: exploring the role of total serum IgE, blood eosinophils, and FeNO as markers of type 2 inflammation

BACKGROUND

While a connection has been established between serum interleukin-6 (IL-6) levels and the IL-6 gene (- 174G/C) polymorphism in allergic diseases such as asthma, its specific association with severe asthma remains unexplored. This study examined the relationship between the IL-6 (- 174G/C) gene polymorphism and mild and severe asthma, focusing on its influence on type 2 inflammation.

METHODS

Our study comprised 98 patients with mild asthma and 116 with severe asthma. Additionally, we recruited 121 healthy participants to serve as controls for comparative analyses. The IL-6 gene (- 174G/C) polymorphism was assessed utilizing the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

In our study, the risk of mild asthma exhibited a significant fourfold increase in individuals with the GG genotype pattern compared to healthy controls, yielding an odds ratio (OR) of 4.4 (p < 0.001). Conversely, we found no significant correlation between the IL-6 - 174G/C gene polymorphism and severe asthma when compared to the healthy control group. However, a noteworthy pattern emerged when we compared subgroups of mild and severe asthma. The risk of severe asthma increased fivefold in individuals with the GC polymorphism pattern, with an OR of 4.99 (p < 0.001), while the likelihood of mild asthma showed a similar fourfold increase with the GG polymorphism pattern, OR = 4.4 (p < 0.001). Consequently, we observed a significantly higher frequency of the C allele in patients with severe asthma, whereas the G allele was more prevalent in individuals with mild asthma (p = 0.05). Additionally, the correlation between markers of type 2 inflammation and the dominant model of the IL-6 gene -174G/C polymorphism (CC + CG vs GG) revealed a significant increase in total serum immunoglobulin E (IgE), Blood Eosinophil Counts (BEC), and Fractional Exhaled Nitric Oxide (FeNO) levels in asthmatic patients with the CC + CG gene pattern compared to those with GG, with p-values of 0.04, 0.03, and 0.04, respectively. Furthermore, after adjusting for other risk factors, the likelihood of developing severe asthma increased from fourfold to eightfold, with an OR of 8.12 (p = 0.01) with (CC + CG) gene pattern. Other predictors for severe asthma included older age and childhood-onset disease (OR = 1.13 and 19.19, p < 0.001). Allergic rhinitis (AR) and nasal polyps (NP) also demonstrated a substantial association with an increased risk of severe asthma, with odds ratios of 5 and 32.29 (p = 0.01 and < 0.001), respectively. Additionally, elevated Body Mass Index (BMI), BEC, and FeNO were linked to severe asthma, with ORs of 1.11, 1.00, and 1.04, respectively (p = 0.04, 0.05, and 0.001).

CONCLUSION

This study illuminated the intricate relationship between the IL-6 gene polymorphism, type 2 inflammation markers, and diverse risk factors in shaping asthma severity. As a significant association between the GG polymorphism of the IL-6 gene (- 174G/C) and mild asthma was found, while possessing at least one C allele, whether in a homozygous (CC) or heterozygous (CG) combination, independently predicts the likelihood of severe asthma.

Atopic dermatitis endotypes: knowledge for personalized medicine

PURPOSE OF REVIEW

Endotypes are clinically relevant phenotypes that can be explained by molecular mechanisms, and are defined to predict the development, progression, prognosis and responses to treatment on the individual level. This review summarizes atopic dermatitis phenotypes, endotypes and their potential application for personalized medicine.

RECENT FINDINGS

Atopic dermatitis can be classified into several phenotypes according to disease courses that likely have common pathophysiology. The genotype is important to define endotypes, but the value of genotype alone remains somewhat limited in most atopic dermatitis patients. Recent studies have demonstrated that atopic dermatitis phenotypes according to ethnicity or age can be classified into endotypes based on the dominant immunologic markers, that is TH1/TH2/TH17/TH22 cells. Newly developed biologic agents targeting specific cytokines show therapeutic potential in a personalized medicine approach.

SUMMARY

Cytokine-based endotypes in different age groups or ethnic groups have contributed to expanding our understanding of atopic dermatitis. Recent biologics or small molecules can be used for more personalized treatment of atopic dermatitis. Further research using integrated multiomic analysis is needed to define a more detailed classification of endotypes and provide endotype-driven targeted therapies for personalized medicine.

TSLP as druggable target - a silver-lining for atopic diseases?

Atopic diseases refer to common allergic inflammatory diseases such as atopic dermatitis (AD), allergic rhinitis (AR), and allergic asthma (AA). AD often develops in early childhood and may herald the onset of other allergic disorders such as food allergy (FA), AR, and AA. This progression of the disease is also known as the atopic march, and it goes hand in hand with a significantly impaired quality of life as well as a significant economic burden. Atopic diseases usually are considered as T helper type 2 (Th2) cell-mediated inflammatory diseases. Thymic stromal lymphopoietin (TSLP), an epithelium-derived pro-inflammatory cytokine, activates distinct immune and non-immune cells. It has been shown to be a master regulator of type 2 immune responses and atopic diseases. In experimental settings, the inhibition or knockout of TSLP signaling has shown great therapeutic potential. This, in conjunction with the increasing knowledge about the central role of TSLP in the pathogenesis of atopic diseases, has sparked an interest in TSLP as a druggable target. In this review, we will discuss the autocrine and paracrine effects of TSLP, how it regulates the tissue microenvironment and drives atopic diseases, which provide the rationale for the increasing interest in TSLP as a druggable target.

A chalcone derivative suppresses the induction of TSLP in mice and human keratinocytes and attenuates OVA-induced antibody production in mice

Thymic stromal lymphopoietin (TSLP) is a key epithelial-derived factor that aggravates allergic diseases. Therefore, TSLP inhibitors are candidate compounds for the treatment of allergic diseases. Previously, we reported that KCMH-1, a mouse keratinocyte cell line, constitutively produces TSLP. In this study, we tried to identify inhibitors of TSLP by screening 2169 compounds in KCMH-1 cells and found one such chalcone derivative (code no. 16D10). 16D10 inhibited TSLP expression and TSLP promoter activation in HaCaT cells, a human keratinocyte cell line. Although nuclear factor kappa-B (NF-κB) is a key transcription factor for the induction of TSLP, 16D10 did not inhibit the activation pathway of NF-κB, such as degradation of inhibitor of κB (IκB) and p65 nuclear translocation. 16D10 activated the Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor (erythroid-derived 2)-like 2 (Nrf2) system, although this system was not involved in the inhibitory effect of 16D10. 16D10 also inhibited TSLP production in a lipopolysaccharide (LPS)- or ovalbumin (OVA)-induced air-pouch-type inflammation model. Further, repeated 16D10 administration diminished serum immunoglobulin G1 (IgG1) and IgE concentration in an OVA-induced air-pouch-type sensitization model. Taken together, these results indicate that 16D10 is an inhibitor of TSLP production and has an anti-allergic effect. This inhibitory effect is independent of the activation of NF-κB and the Keap1-Nrf2 system. Therefore, 16D10 could be a new type of candidate drug for allergic diseases.

Mechanisms by Which Atopic Dermatitis Predisposes to Food Allergy and the Atopic March

The Atopic march denotes the progression from atopic dermatitis (AD) to the development of other allergic disorders such as immunoglobulin (Ig) E-mediated food allergy, allergic rhinitis and asthma in later childhood. There is increasing evidence from prospective birth cohort studies that early-onset AD is a risk factor for other allergic diseases or is found in strong association with them. Animal studies now provide mechanistic insights into the pathways that may be responsible for triggering the progression from the skin barrier dysfunction seen in AD to epicutaneous sensitization, food allergy and allergic airway disorders. Recent large randomized controlled trials have demonstrated the efficacy of early interventions targeted at AD and food allergy prevention. These show great promise for research into future strategies aimed at prevention of the atopic march.

New Cytokines in the Pathogenesis of Atopic Dermatitis-New Therapeutic Targets

Atopic dermatitis (AD) is a recurrent, chronic, and inflammatory skin disease, which processes with severe itchiness. It often coexists with different atopic diseases. The number of people suffering from AD is relatively high. Epidemiological research demonstrates that 15–30% of children and 2–10% adults suffer from AD. The disease has significant negative social and economic impacts, substantially decreasing the quality of life of the patients and their families. Thanks to enormous progress in science and technology, it becomes possible to recognise complex genetic, immunological, and environmental factors and epidermal barrier defects that play a role in the pathogenesis of AD. We hope that the new insight on cytokines in AD will lead to new, individualised therapy and will open different therapeutic possibilities. In this article, we will focus on the cytokines, interleukin (IL)-17, IL-19, IL-33, and TSLP (thymic stromal lymphopoietin), which play a significant role in AD pathogenesis and may become the targets for future biologic therapies in AD. It is believed that the new era of biological drugs in AD will give a chance for patients to receive more successful treatment.

Thymic stromal lymphopoietin drives the development of IL-13+ Th2 cells

T helper 2 (Th2) cells are defined by their ability to produce the hallmark cytokine IL-4. However, to mediate allergic inflammation in tissues, Th2 cells must secrete additional cytokines including IL-13 and IL-5. We used IL-4 and IL-13 dual-reporter mice to show that naive CD4⁺ T cells cultured in the presence of IL-4 and thymic stromal lymphopoietin (TSLP) generate a population of IL-4^negIL-13^pos Th2 cells that develop from IL-4^neg precursors and express the Th2 effector cytokines IL-5 and IL-9. In vivo, high TSLP levels promote the development of a similar population of IL-4^negIL-13^pos T cells that also express Gata3, Il5, and Il3 transcripts. Thus, TSLP drives the early differentiation of a distinct population of effector Th2 cells with pro-inflammatory properties.

T helper 2 (Th2) cells are pivotal in the development of allergy. Allergen exposure primes IL-4⁺ Th2 cells in lymph node, but production of effector cytokines including IL-5 and IL-13 is thought to require additional signals from antigen and the environment. Here we report that a substantial proportion of naive CD4⁺ T cells in spleen and lymph node express receptors for the epithelium-derived inflammatory cytokine thymic stromal lymphopoietin (TSLP). Culture of naive CD4⁺ T cells in anti-(a)CD3, aCD28, and TSLP-supplemented Th2 conditions enabled the development of a unique population of IL-13-single positive (IL-13-SP) CD4⁺ T cells; TSLP and Th2 conditions were both required for their development. Sorting experiments revealed that IL-13-SP Th2 cells originated from IL-4-negative precursors and coexpressed transcripts for the Th2 cytokines IL-5 and IL-9. In vivo, high TSLP levels acted directly on CD4⁺ T cells to induce the development of IL-13-SP and IL-4⁺IL-13⁺ double-positive populations in lymph node. These cells were phenotypically similar to Th2 effector cells and were CXCR5^lowPD1^low and expressed low levels of Bcl6 and Il21 transcripts and high levels of Gata3, Il3, and Il5. Our findings suggest a role of TSLP in directly promoting Th2 cell effector function and support the notion of TSLP as a key driver of Th2 inflammation.

Co-Activation of Glucocorticoid Receptor and Peroxisome Proliferator-Activated Receptor-γ in Murine Skin Prevents Worsening of Atopic March

Children with atopic dermatitis show an increased risk to develop asthma later in life, a phenomenon referred to as "atopic march," which emphasizes the need for secondary prevention therapies. This study aimed to investigate whether relief of skin inflammation by glucocorticoids and peroxisome proliferator-activated receptor agonists might influence the subsequent development of asthma in a murine model for the atopic march in which mice were repeatedly exposed to house dust mite via the skin, followed by exposure to house dust mite in lungs. To abrogate atopic dermatitis, mice received topical treatment with glucocorticoid receptor/peroxisome proliferator-activated receptor-γ agonists. Nuclear receptor ligand effects were assessed on primary keratinocytes and dendritic cells, as central players in skin inflammation. Prior house dust mite-induced skin inflammation aggravates allergic airway inflammation and induces a mixed T helper type 2/T helper type 17 response in the lungs. Cutaneous combined activation of glucocorticoid receptor/peroxisome proliferator-activated receptor-γ reduced skin inflammation to a higher extent compared to single activation. Additive anti-inflammatory effects were more prominent in dendritic cells, as compared to keratinocytes. Alleviation of allergic skin inflammation by activation of glucocorticoid receptor/peroxisome proliferator-activated receptor-γ appeared insufficient to avoid the allergic immune response in the lungs, but efficiently reduced asthma severity by counteracting the Th17 response. Glucocorticoid receptor/peroxisome proliferator-activated receptor-γ co-activation represents a potent remedy against allergic skin inflammation and worsening of atopic march.

Eosinophilic esophagitis (EoE) genetic susceptibility is mediated by synergistic interactions between EoE-specific and general atopic disease loci

BACKGROUND

Eosinophilic esophagitis (EoE) is an esophageal inflammatory disease associated with atopic diseases. Thymic stromal lymphopoietin (TSLP) and calpain 14 (CAPN14) genetic variations contribute to EoE, but how this relates to atopy is unclear.

OBJECTIVE

The purpose of this study was to explore the relationship between EoE, atopy, and genetic risk.

METHODS

EoE-atopy enrichment was tested by using 700 patients with EoE and 801 community control subjects. Probing 372 single nucleotide polymorphisms (SNPs) in 63 atopy genes, we evaluated EoE associations using 412 nonatopic and 868 atopic disease control subjects. Interaction and stratified analyses of EoE-specific and atopy-related SNPs were performed.

RESULTS

Atopic disease was enriched in patients with EoE (P < .0001). Comparing patients with EoE and nonatopic control subjects, EoE associated strongly with IL-4/kinesin family member 3A (IL4/KIF3A) (P = 2.8 × 10^-6; odds ratio [OR], 1.87), moderately with TSLP (P = 1.5 × 10^-4; OR, 1.43), and nominally with CAPN14 (P = .029; OR, 1.35). Comparing patients with EoE with atopic disease control subjects, EoE associated strongly with ST2 (P = 3.5 × 10^-6; OR, 1.77) and nominally with IL4/KIF3A (P = .019; OR, 1.25); TSLP's association persisted (P = 4.7 × 10^-5; OR, 1.37), and CAPN14's association strengthened (P = .0001; OR, 1.71). Notably, there was gene-gene interaction between TSLP and IL4 SNPs (P = .0074). Children with risk alleles for both genes were at higher risk for EoE (P = 2.0 × 10^-10; OR, 3.67).

CONCLUSIONS

EoE genetic susceptibility is mediated by EoE-specific and general atopic disease loci, which can have synergistic effects. These results might aid in identifying potential therapeutics and predicting EoE susceptibility.

International consensus (ICON) on: clinical consequences of mite hypersensitivity, a global problem

Since mite allergens are the most relevant inducers of allergic diseases worldwide, resulting in significant morbidity and increased burden on health services, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), the European Academy of Allergy and Clinical Immunology (EAACI), and the World Allergy Organization (WAO), has proposed to issue an International Consensus (ICON) on the clinical consequences of mite hypersensitivity. The objectives of this document are to highlight aspects of mite biology that are clinically relevant, to update the current knowledge on mite allergens, routes of sensitization, the genetics of IgE responses to mites, the epidemiologic aspects of mite hypersensitivity, the clinical pictures induced by mites, the diagnosis, specific immunotherapeutic approaches, and prevention.

Developments in the field of allergy in 2014 through the eyes of Clinical and Experimental Allergy

The pathogenesis of asthma continues to be a major topic of interest to our authors with reviews and original papers on the role of viruses, mechanisms of inflammation, biomarkers, and phenotypes of asthma being major topics. A number of papers described new treatments for asthma focusing on blocking the Th2 response reflecting the fact that two decades of work in this area is finally bearing fruit. The pathogenesis of chronic rhinosinusitis is a growing area of interest, but there has been less on the genetics of airways disease than in previous years possibly reflecting the degree of rigour (and therefore a smaller body of work), with which these sorts of studies are now being undertaken. There continues to be a wide range of papers dealing with mechanisms of allergic disease ranging from clinical-based studies to basic research and the use of in vivo animal models especially mice. As before, mechanisms and new approaches to immunotherapy are common themes. Several were published in the allergens section investigating modification of allergens to increase their effectiveness and reduce the risk of adverse events. Risk factors for allergic disease was a common theme in the epidemiology section and food allergy a common theme in clinical allergy with papers on the development of protocols to induce tolerance and attempts to find biomarkers to distinguish sensitization from allergic disease. This was another exciting year for the editors, and we hope the readers of the journal.

Atopic dermatitis phenotype with early onset and high serum IL-13 is linked to the new development of bronchial hyperresponsiveness in school children

BACKGROUND

Atopic dermatitis (AD) is characterized by a heterogeneous clinical spectrum, and some forms of AD are associated with the initial steps of allergic march. The aims of this study were to determine AD phenotypes in school-age children and investigate their associations with the allergic march in each cluster.

METHODS

We included 242 children (6-8 years) with current AD from the Children's HEalth and Environmental Research study, a 4-year prospective follow-up study with 2-year survey intervals. Latent class analysis was used. Serum IL-13 and thymic stromal lymphopoietin (TSLP) levels at the time of enrollment were measured using ELISA.

RESULTS

We identified four current AD phenotypes in children, characterized as 'early onset with low atopy' (26.4% of the sample; group 1), 'early onset with high atopy and high eosinophil percentages' (48.3%; group 2), 'late onset with low atopy' (9.9%; group 3), and 'late onset with high atopy and normal eosinophils' (15.3%; group 4). Although groups 2 and 4 demonstrated high atopic burden, children in group 2 showed the persistence of AD and eosinophilia associated with a high prevalence of new cases of bronchial hyper-responsiveness and asthma symptoms during follow-up. The serum IL-13 level was significantly increased in the early-onset AD groups, but there was no significant difference in the serum TSLP levels across all four groups.

CONCLUSION

An allergic march-associated AD phenotype exists that is characterized by early onset of AD with its persistence, increased serum IL-13 levels, high atopy, and a persistently increased blood eosinophil percentage.

The Hot-Water Extract of Smilacis Chinae Rhizome Suppresses 2,4-Dinitrochlorobenzene and House Dust Mite-Induced Atopic Dermatitis-Like Skin Lesions in Mice

Smilacis Chinae Rhizome (SCR) has been used as an oriental folk medicine for various biological activities. However, its effect on atopic dermatitis (AD) remains undetermined to date. We assessed the effect of orally administered hot-water extract of SCR on AD-like skin lesions in mice and its underlying mechanisms. AD-like murine model was prepared by repeated alternate application of house dust mite (Dermatophagoides farinae) extract (DFE) and 2,4-dinitrochlorobenzene (DNCB) for 4 weeks, topically to the ears. Daily oral administration of SCR for 3 and 4 weeks significantly reduced inflammatory ear thickening, with the effect being enhanced at the earlier start and longer period of administration. This effect was accompanied by a significant decrease in both Th2 and Th1 serum antibodies (total IgE, DFE-specific IgE, and IgG2a). Histological analysis showed that SCR markedly decreased the epidermal/dermal ear thickening and the dermal infiltration of inflammatory cells. Furthermore, SCR suppressed DFE/DNCB-induced expression of IL-4, IL-13, IL-17, IL-18, TSLP, and IFN-γ genes in the ear tissue. Taken together, our observations demonstrate that chronic oral administration of SCR exerts beneficial effect in mouse AD model, suggesting that SCR has the therapeutic potential as an orally active treatment of AD by modulating both Th1 and Th2 responses.

TSLP polymorphisms, allergen exposures, and the risk of atopic disorders in children

BACKGROUND

Thymic stromal lymphopoietin (TSLP) polymorphisms influence atopy risk. TSLP might constitute a key interface between the environment and the allergic immune response. However, whether the effects of TSLP polymorphisms on atopic dermatitis (AD) are modified by allergic sensitization is not clear.

OBJECTIVE

To evaluate the joint effect of allergic sensitization and TSLP polymorphisms on AD and to test whether TSLP polymorphisms increase the risk of asthma in children with AD.

METHODS

A total of 1,520 kindergarten children (375 with AD and 1,145 controls) selected from the Childhood Environment and Allergic Diseases Study cohort in 2010 were enrolled. Information about allergic diseases and environmental exposures was collected by questionnaire. Skin prick tests were performed to measure allergic sensitization. TSLP polymorphisms were genotyped by TaqMan assay. Logistic regressions were conducted to estimate the association among TSLP polymorphisms, allergic sensitization, and AD. For replication, a subsample of the British Isle of Wight birth cohort was used.

RESULTS

The TSLP rs2289278 CC genotype increased the risk of AD (odds ratio 1.90, 95% confidence interval 1.12-3.22). In children sensitized to certain allergens, a genetic predisposition (rs2289278 genotype CC) significantly increased the risk of AD. These findings were replicated in the British subsample using rs2289276 genotypes TT and TC, which are in linkage disequilibrium with rs2289278. In subjects with AD, the rs2289278 C allele also significantly increased the risk of developing asthma (odds ratio 8.31, 95% confidence interval 1.08-64.13).

CONCLUSION

The association of rs2289278 with AD was stronger in children with allergic sensitization than in children without atopy. TSLP polymorphisms also increased the risk of asthma in children with AD.

Asthma phenotypes and IgE responses

The discovery of IgE represented a major breakthrough in allergy and asthma research, whereas the clinical interest given to IgE in asthma has been blurred until the arrival of anti-IgE biotherapy. Novel facets of the complex link between IgE and asthma have been highlighted by the effect of this treatment and by basic research. In parallel, asthma phenotyping recently evolved to the concept of endotypes, relying on identified/suspected pathobiological mechanisms to phenotype patients, but has not yet clearly positioned IgE among biomarkers of asthma.In this review, we first summarise recent knowledge about the regulation of IgE production and its main receptor, FcεRI. In addition to allergens acting as classical IgE inducers, viral infections as well as air pollution may trigger the IgE pathway, notably resetting the threshold of IgE sensitivity by regulating FcεRI expression. We then analyse the place of IgE in different asthma endo/phenotypes and discuss the potential interest of IgE among biomarkers in asthma.

The importance of TSLP in allergic disease and its role as a potential therapeutic target

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine similar to IL- 7, whose gene is located on chromosome 5q22.1 and it exerts its biological function through the TSLP-Receptor (TSLP-R). TSLP is expressed primarily by epithelial cells at barrier surfaces such as the skin, gut and lung in response to danger signals. Since it was cloned in 1994, there has been accumulating evidence that TSLP is crucial for the maturation of antigen presenting cells and hematopoietic cells. TSLP genetic variants and its dysregulated expression have been linked to atopic diseases such as atopic dermatitis, asthma, allergic rhinitis and eosinophilic esophagitis.

FLG P478S polymorphisms and environmental risk factors for the atopic march in Taiwanese children: a prospective cohort study

BACKGROUND

Little is known about the role of genetic and environmental modifiers in atopic march.

OBJECTIVE

To investigate the effects of filaggrin (FLG) P478S polymorphisms and environmental factors on the risk of asthma in a cohort of children with atopic dermatitis (AD).

METHODS

In 2010, 3,246 children from Childhood Environment and Allergic Diseases Cohort Study cohort were recruited. There were 485 children with AD who were invited for further clinical evaluation. Environmental exposures and skin prick tests for allergens were collected at 3 years of age and the development of asthma was determined at 6 years. Multivariate logistic regressions were performed to estimate the association between genetic and environmental factors and the development asthma in children with AD.

RESULTS

Of 397 children with AD who completed the follow-up, 97 developed asthma. After controlling for potential confounders, only mite sensitizations (odds ratio 1.89, 95% confidence interval 1.10-3.25) and the FLG TT genotype (odds ratio 2.26, 95% confidence interval 1.33-3.84) were significantly associated with the development of asthma in children with AD. Mite sensitizations and FLG variants had a synergistic effect on the development of asthma. When children with FLG variants were exposed to mite, the risk for asthma was compounded compared with those with FLG variants without mite exposure (odds ratio 3.58, 95% confidence interval 1.81-7.08).

CONCLUSION

Mite sensitization and the FLG TT genotype couldt be associated with the development of atopic march.

[Human dendritic cells in allergic asthma and rhinitis]

The role of dendritic cells (DC) in the pathogenesis of allergic asthma and rhinitis has been highlighted for 15 years. In this review, we summarize key findings concerning DC function in airway allergy and focus on studies performed in human. DC coming from allergic patients have specific characteristics, including significant expression of high affinity receptor for IgE as well as a propensity for Th2 responses induction following priming with allergen and/or epithelial cytokines. Mechanistic data concerning this DC dysfunction in asthma also provide perspectives for innovating therapies.

Update on skin allergy

Skin diseases with an allergic background such as atopic dermatitis, allergic contact dermatitis, and urticaria are very common. Moreover, diseases arising from a dysfunction of immune cells and/or their products often manifest with skin symptoms. This review aims to summarize recently published articles in order to highlight novel research findings, clinical trial results, and current guidelines on disease management. In recent years, an immense progress has been made in understanding the link between skin barrier dysfunction and allergic sensitization initiating the atopic march. In consequence, new strategies for treatment and prevention have been developed. Novel pathogenic insights, for example, into urticaria, angioedema, mastocytosis, led to the development of new therapeutic approaches and their implementation in daily patient care. By understanding distinct pathomechanisms, for example, the role of IL-1, novel entities such as autoinflammatory diseases have been described. Considerable effort has been made to improve and harmonize patient management as documented in several guidelines and position papers.

Cutaneous or respiratory exposures to peanut allergens in mice and their impacts on subsequent oral exposure

BACKGROUND

Recent data suggested that non-gastrointestinal exposure can lead to sensitisation to food allergens. We thus assessed the immune impact of respiratory or cutaneous exposure to peanut proteins on non-altered epithelium and investigated the effect of such pre-exposure on subsequent oral administration of peanut.

METHODS

BALB/cJ mice were exposed to purified Ara h 1 or to a non-defatted roasted peanut extract (PE) by simple deposit of allergens solutions on non-altered skin or in the nostrils. Exposures were performed 6 times at weekly intervals. Pre-exposed mice then received intra-gastric administrations of PE alone or in the presence of the Th2 mucosal adjuvant cholera toxin (CT). The specific humoral and cellular immune response was assessed throughout the protocol.

RESULTS

Both cutaneous and respiratory exposures led to the production of specific IgG1. Local and systemic IL-5 and IL-13 production were also evidenced, demonstrating activation of specific Th2 cells. This effect was dose-dependent and most efficient via the respiratory route. Moreover, these pre-exposures led to the production of specific IgE antibodies after gavage with PE, whatever the presence of CT.

CONCLUSIONS

Cutaneous or respiratory exposures to peanut induce Th2 priming in mice. Moreover, pre-exposures promote further sensitisation via the oral route without the use of CT; this proposes a new adjuvant-free experimental model of sensitisation to food that may reflect a realistic exposure pattern in infants. These results also suggest that non-gastrointestinal peanut exposure should be minimised in high-risk infants, even those with non-altered skin, to potentially reduce allergic sensitisation to this major food allergen.

Exposure to food allergens through inflamed skin promotes intestinal food allergy through the thymic stromal lymphopoietin-basophil axis

BACKGROUND

Exposure to food allergens through a disrupted skin barrier has been recognized as a potential factor in the increasing prevalence of food allergy.

OBJECTIVE

We sought to test the immunologic mechanisms by which epicutaneous sensitization to food allergens predisposes to intestinal food allergy.

METHODS

Mice were epicutaneously sensitized with ovalbumin or peanut on an atopic dermatitis-like skin lesion, followed by intragastric antigen challenge. Antigen-specific serum IgE levels and T(H)2 cytokine responses were measured by ELISA. Expression of type 2 cytokines and mast cell proteases in the intestine were measured by using real-time PCR. Accumulation of basophils in the skin and mast cells in the intestine was examined by using flow cytometry. In vivo basophil depletion was achieved by using diphtheria toxin treatment of Baso-DTR mice. For cell-transfer studies, the basophil population was expanded in vivo by means of hydrodynamic tail vein injection of thymic stromal lymphopoietin (TSLP) cDNA plasmid.

RESULTS

Sensitization to food allergens through an atopic dermatitis-like skin lesion is associated with an expansion of TSLP-elicited basophils in the skin that promote antigen-specific T(H)2 cytokine responses, increased antigen-specific serum IgE levels, and accumulation of mast cells in the intestine, promoting the development of intestinal food allergy. Critically, disruption of TSLP responses or depletion of basophils reduced the susceptibility to intestinal food allergy, whereas transfer of TSLP-elicited basophils into intact skin promoted disease.

CONCLUSION

Epicutaneous sensitization on a disrupted skin barrier is associated with accumulation of TSLP-elicited basophils, which are necessary and sufficient to promote antigen-induced intestinal food allergy.

The biology of thymic stromal lymphopoietin (TSLP)

Originally shown to promote the growth and activation of B cells, thymic stromal lymphopoietin (TSLP) is now known to have wide-ranging impacts on both hematopoietic and nonhematopoietic cell lineages, including dendritic cells, basophils, eosinophils, mast cells, CD4⁺, CD8⁺ and natural killer T cells, B cells and epithelial cells. While TSLP's role in the promotion of TH2 responses has been extensively studied in the context of lung- and skin-specific allergic disorders, it is becoming increasingly clear that TSLP may impact multiple disease states within multiple organ systems, including the blockade of TH1/TH17 responses and the promotion of cancer and autoimmunity. This chapter will highlight recent advances in the understanding of TSLP signal transduction, as well as the role of TSLP in allergy, autoimmunity and cancer. Importantly, these insights into TSLP's multifaceted roles could potentially allow for novel therapeutic manipulations of these disorders.

Immunology of atopic eczema: overcoming the Th1/Th2 paradigm

Atopic eczema (AE) is a challenge for modern medicine, because it is prevalent, severely affects quality of life of patients and their families, and causes high socioeconomic costs. The pathogenesis of AE is complex. While initial studies suggested a Th2 deviation as primary reason for the disease, numerous studies addressed a genetically predetermined impaired epidermal barrier as leading cause in a subgroup of patients. Recently, immune changes beyond the initial Th2 concept were defined in AE, with a role for specialized dendritic cells as well as newly identified T helper cell subsets such as Th17 and Th22 cells. Furthermore, trigger factors are expanded beyond classical Th2 allergens such as pollen or house dust mites to microbial products as well as self-antigens. This review pieces together our current understanding of immune as well as barrier abnormalities into the pathogenesis mosaic of AE.

The absence of a microbiota enhances TSLP expression in mice with defective skin barrier but does not affect the severity of their allergic inflammation

Evidence is accumulating to suggest that our indigenous microbial communities (microbiota) may play a role in modulating allergic and immune disorders of the skin (Gallo and Nakatsuji, 2011; Macia et al., 2012). To examine the link between the microbiota and atopic dermatitis, we examined a mouse model of defective cutaneous barrier function with an atopic dermatitis-like disease due to loss of Notch signaling. Comparisons of conventionally-raised (CONV-R) and germ-free (GF) mice revealed a similar degree of allergic skin inflammation, systemic atopy, and airway hypersensitivity. GF mutant animals expressed significantly higher levels of thymic stromal lymphopoietin (TSLP), a major proinflammatory cytokine released by skin with defective barrier function, resulting in a more severe B-lymphoproliferative disorder that persisted into adulthood. These findings suggest a role for the microbiota in ameliorating stress signals released by keratinocytes in response to perturbation in cutaneous barrier function.

The pathologic and clinical intersection of atopic and autoimmune disease

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

Characterization of different courses of atopic dermatitis in adolescent and adult patients

BACKGROUND

Atopic dermatitis (AD) starts most often during the first years of life and goes into remission in a high proportion of cases during childhood. However, in severe cases, AD persists until adulthood or starts and relapses later in life. So far, studies investigating the natural course of AD during adolescence and adulthood are rare. The aim of our study was to classify different courses of AD and to correlate these with specific risk factors for severe variants of AD.

METHODS

A detailed clinical examination and retrospective evaluation of the history of the disease were performed in a collective of 725 adolescent and adult patients with AD. Laboratory data including total and specific IgE were evaluated.

RESULTS

Six hundred and seven patients of 725 patients could be classified into course types. Of these 607 patients 85.7% could be classified into five main different course types of all 31 course types recorded. The highest differences in the number of sensitizations, total immunoglobulin E serum levels and predilection of the skin lesions were observed between patients with an early type of onset of AD and a chronic persisting course until adulthood and patients with a late type of onset of AD, that is, after the 20th year of life.

CONCLUSION

Our data show that the natural course of AD can be divided into subgroups that display different clinical features. The data support the assumption of a broad heterogeneity of AD in adolescence and adulthood and emphasize the future need for careful stratification of patients with AD.

TSLP: A Key Regulator of Asthma Pathogenesis

Asthma is a complex disorder of the airways that is characterized by T helper type 2 (Th2) inflammation. The pleiotrophic cytokine TSLP has emerged as an important player involved in orchestrating the inflammation seen in asthma and other atopic diseases. Early research elucidated the role of TSLP on CD4⁺ T cells, and recent work has revealed the impact of TSLP on multiple cell types. Furthermore, TSLP plays an important role in the sequential progression of atopic dermatitis to asthma, clarifying the key role of TSLP in the pathogenesis of asthma, a finding with therapeutic implications.

Update in clinical allergy and immunology

In the recent years, a tremendous body of studies has addressed a broad variety of distinct topics in clinical allergy and immunology. In this update, we discuss selected recent data that provide clinically and pathogenetically relevant insights or identify potential novel targets and strategies for therapy. The role of the microbiome in shaping allergic immune responses and molecular, as well as cellular mechanisms of disease, is discussed separately and in the context of atopic dermatitis, as an allergic model disease. Besides summarizing novel evidence, this update highlights current areas of uncertainties and debates that, as we hope, shall stimulate scientific discussions and research activities in the field.