Filaggrin mutations associated with skin and allergic diseases

LILRA6 copy number variation correlates with susceptibility to atopic dermatitis

Leukocyte immunoglobulin-like receptors (LILR) are expressed mostly on myelomonocytic cells where they are mediators of immunological tolerance. Two LILR genes, LILRA3 and LILRA6, exhibit marked copy number variation. We assessed the contribution of these genes to atopic dermatitis (AD) by analysing transmission in 378 AD families. The data indicated that copies of LILRA6 were over-transmitted to affected patients. They are consistent with a contribution of LILR genes to AD. They could affect the equilibrium between activating and inhibitory signals in the immune response.

Basis for the gain and subsequent dilution of epidermal pigmentation during human evolution: The barrier and metabolic conservation hypotheses revisited

The evolution of human skin pigmentation must address both the initial evolution of intense epidermal pigmentation in hominins, and its subsequent dilution in modern humans. While many authorities believe that epidermal pigmentation evolved to protect against either ultraviolet B (UV-B) irradiation-induced mutagenesis or folic acid photolysis, we hypothesize that pigmentation augmented the epidermal barriers by shifting the UV-B dose-response curve from toxic to beneficial. Whereas erythemogenic UV-B doses produce apoptosis and cell death, suberythemogenic doses benefit permeability and antimicrobial function. Heavily melanized melanocytes acidify the outer epidermis and emit paracrine signals that augment barrier competence. Modern humans, residing in the cooler, wetter climes of south-central Europe and Asia, initially retained substantial pigmentation. While their outdoor lifestyles still permitted sufficient cutaneous vitamin D3 (VD3) synthesis, their marginal nutritional status, coupled with cold-induced caloric needs, selected for moderate pigment reductions that diverted limited nutritional resources towards more urgent priorities (=metabolic conservation). The further pigment-dilution that evolved as humans reached north-central Europe (i.e., northern France, Germany), likely facilitated cutaneous VD3 synthesis, while also supporting ongoing, nutritional requirements. But at still higher European latitudes where little UV-B breaches the atmosphere (i.e., present-day UK, Scandinavia, Baltic States), pigment dilution alone could not suffice. There, other nonpigment-related mutations evolved to facilitate VD3 production; for example, in the epidermal protein, filaggrin, resulting in reduced levels of its distal metabolite, trans-urocanic acid, a potent UV-B chromophore. Thus, changes in human pigmentation reflect a complex interplay between latitude, climate, diet, lifestyle, and shifting metabolic priorities.

Quality of life and disease severity in patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) affects quality of life (QoL) negatively in patients and their families. We examined the relationship between disease severity and QoL in patients with AD.

METHODS

Consecutive, newly referred outpatients with AD, 4 years of age or older, were assessed from January 2012 onwards by means of the dermatology life quality index (DLQI, range 0-30), the Scoring of AD (SCORAD) disease severity score (range 0-103), filaggrin gene (FLG) mutation status and paraclinical tests related to allergy.

RESULTS

A total of 250 patients with a mean age of 26.0 years were identified with complete data on DLQI; 148 (59.2%) females and 102 (40.8%) males. Of these 45.6% had asthma, 46.8% had hay fever, 22.7% had a loss-of-function mutation in FLG, and 61.9% had one or more inhalant allergic sensitizations. The correlation between SCORAD and DLQI was 0.42 (P < 0.001). After multivariate adjustment there was an increasing mean DLQI score with increasing disease severity measured by SCORAD (DLQI in mild = 5.30, moderate = 8.59 and severe = 11.94 AD), P-value for difference between groups <0.001; a higher mean DLQI among females than males (9.73 vs. 8.34), P = 0.028; and among patients reporting facial eczema (9.88 vs. 6.24), P = 0.012. No statistically significant influence on DLQI was found for hand or foot eczema, age, blood eosinophil count, allergic sensitization, asthma, hay fever, FLG mutation status and smoking. FLG null mutation status was not significantly associated with SCORAD.

CONCLUSION

AD impacts negatively on the QoL, proportional to the severity of the disease. Furthermore, female sex and facial eczema are associated with low QoL. Positive FLG null mutation status is not associated with QoL or disease severity.

Neonatal risk factors of atopic dermatitis in Denmark - Results from a nationwide register-based study

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin condition with a multifactorial etiopathogenesis. Studies have suggested that several perinatal factors may influence the risk of AD in early childhood. We investigated possible neonatal risk factors such as jaundice, blue light phototherapy, birthweight, gestational age at birth, and season of birth on the risk of developing AD in the first 5 years of life.

MATERIALS & METHODS

Data were collected through Danish nationwide administrative registers. All newborn children between 1997 and 2007 (n = 673,614) were included in the cohort. Incidence rate ratios (IRRs) were estimated with 95% confidence intervals (95% CIs) by multivariate Poisson regression analyses.

RESULTS

We identified a total of 85,743 children with AD in the first 5 years of life. The risk of AD was slightly increased in children with neonatal jaundice (IRR 1.13 [95% CI 1.06-1.21]). Preterm birth was inversely associated with the risk of AD (IRR 0.74, [95% CI 0.68-0.81]) as well as low birthweight (IRR 0.68, [95% CI 0.61-0.75]). Children born in fall and winter seasons had an increased risk of AD compared to spring and summer. No association between neonatal blue light therapy and the risk of AD was found.

CONCLUSIONS

Low birthweight and preterm birth were inversely associated with AD, while neonatal jaundice and cold seasons of birth were associated with an increased risk of AD.

The role of vitamin D in cancer prevention

Vitamin D, also known as cholecalciferol, is the precursor to the active steroid hormone 1, 25-dihydroxyvitamin D3 (calcitriol; 1, 25(OH)2D3). The main physiological role for 1, 25(OH)2D3 is to regulate calcium and inorganic phosphate homeostasis for bone health. More recently, vitamin D has been investigated for its effects in the prevention and treatment of a variety of diseases such as cancer, autoimmune disorders, and cardiovascular disease. Preclinical data strongly support a role for vitamin D in the prevention of cancer through its anti-proliferative, pro-apoptotic, and anti-angiogenic effects on cells. Epidemiologic and clinical studies have shown mixed data on the correlation between serum vitamin D levels and cancer risk. This report seeks to outline results from the most recent preclinical and clinical studies investigating the potential role of vitamin D in cancer prevention.

Pelota Regulates Epidermal Differentiation by Modulating BMP and PI3K/AKT Signaling Pathways

The depletion of evolutionarily conserved pelota protein causes impaired differentiation of embryonic and spermatogonial stem cells. In this study, we show that temporal deletion of pelota protein before epidermal barrier acquisition leads to neonatal lethality due to perturbations in permeability barrier formation. Further analysis indicated that this phenotype is a result of failed processing of profilaggrin into filaggrin monomers, which promotes the formation of a protective epidermal layer. Molecular analyses showed that pelota protein negatively regulates the activities of bone morphogenetic protein and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathways in the epidermis. To address whether elevated activities of bone morphogenetic protein and PI3K/AKT signaling pathways were the cause for the perturbed epidermal barrier in Pelo-deficient mice, we made use of organotypic cultures of skin explants from control and mutant embryos at embryonic day 15.5. Inhibition of PI3K/AKT signaling did not significantly affect the bone morphogenetic protein activity. However, inhibition of bone morphogenetic protein signaling caused a significant attenuation of PI3K/AKT activity in mutant skin and, more interestingly, the restoration of profilaggrin processing and normal epidermal barrier function. Therefore, increased activity of the PI3K/AKT signaling pathway in Pelo-deficient skin might conflict with the dephosphorylation of profilaggrin and thereby affect its proper processing into filaggrin monomers and ultimately the epidermal differentiation.

The role of filaggrin mutations during pregnancy and postpartum: atopic dermatitis and genital skin diseases

Mutations in the epidermal filaggrin gene (FLG) are associated with skin barrier dysfunction (dry skin, less acidic skin, and fissured skin), and atopic dermatitis (AD) with a severe and persistent course. Because pregnancy and delivery further impairs normal skin barrier functions (immune suppression, mechanical stress), we studied the possible role of FLG mutations on the risk of AD flares, genital infections, and postpartum problems related to perineal trauma. FLG-genotyping was performed in a population-based sample of 1837 women interviewed in the 12th and 30th weeks of pregnancy and 6 months postpartum as part of the Danish National Birth Cohort study 1996-2002. We found that FLG mutations also influence pregnancy-related skin disease; thus, women with FLG mutations had an increased risk of AD flares during pregnancy (OR 10.5, 95% CI 3.6-30.5) and of enduring postpartum physical problems linked to perineal trauma during delivery (OR 11.1, 95% CI 1.1-107.7).

Debates in allergy medicine: Specific immunotherapy in children with atopic dermatitis, the "con" view

Atopic dermatitis (AD) is a common chronic skin condition in children that has a proven association with other atopic conditions and allergies. These associations, like the general pathophysiology of AD, are complex and not fully understood. While there is evidence for the efficacy of specific immunotherapy (SIT) in pediatric asthma and allergic rhinitis (AR), there is a lack of strong data to support its use in AD. IgE has been shown to be elevated in many patients with AD, but it is an unreliable biomarker due to variability and great fluctuation over time, poor positive predictive value for clinically relevant allergy, and poor correlation with disease state. In spite of this, almost all studies of SIT use either positive skin prick testing (SPT) or serum specific IgE levels to guide therapy. Allergen avoidance, with some exceptions, is generally not effective at controlling AD in children. The few studies that have investigated the efficacy of SIT in children with AD have produced conflicting results, and a lack of reproducibility with a standard treatment protocol. Limited studies have shown clinical improvement in mild to moderate AD cases, but no effect on more severe patients. Uncontrolled studies are difficult to interpret, due to the natural history of remission or “outgrowing” of AD over time in many patients without specific interventions. Drawbacks to SIT include the length of treatment, poor compliance, cost, and potential side effect profile. The potential for misdirection of time and energy away from skin directed therapy could negatively impact on AD outcomes.

Advances and highlights in mechanisms of allergic disease in 2015

This review highlights some of the advances in mechanisms of allergic disease, particularly anaphylaxis, including food allergy, drug hypersensitivity, atopic dermatitis (AD), allergic conjunctivitis, and airway diseases. During the last year, a mechanistic advance in food allergy was achieved by focusing on mechanisms of allergen sensitization. Novel biomarkers and treatment for mastocytosis were presented in several studies. Novel therapeutic approaches in the treatment of atopic dermatitis and psoriasis showed that promising supplementation of the infant's diet in the first year of life with immunoactive prebiotics might have a preventive role against early development of AD and that therapeutic approaches to treat AD in children might be best directed to the correction of a TH2/TH1 imbalance. Several studies were published emphasizing the role of the epithelial barrier in patients with allergic diseases. An impaired skin barrier as a cause for sensitization to food allergens in children and its relationship to filaggrin mutations has been an important development. Numerous studies presented new approaches for improvement of epithelial barrier function and novel biologicals used in the treatment of inflammatory skin and eosinophilic diseases. In addition, novel transcription factors and signaling molecules that can develop as new possible therapeutic targets have been reported.

Mast Cells Regulate Epidermal Barrier Function and the Development of Allergic Skin Inflammation

Atopic dermatitis is a chronic inflammatory skin disease characterized by infiltration of eosinophils, T helper cells, and mast cells. The role of mast cells in atopic dermatitis is not completely understood. To define the effects of mast cells on skin biology, we observed that mast cells regulate the homeostatic expression of epidermal differentiation complex and other skin genes. Decreased epidermal differentiation complex gene expression in mice that genetically lack mast cells (Kit(W-sh/W-sh) mice) is associated with increased uptake of protein antigens painted on the skin by dendritic cells (DCs) compared with similarly treated wild-type mice, suggesting a protective role for mast cells in exposure to nominal environmental allergens. To test this further, we crossed Kit(W-sh/W-sh) mice with signal transducer and activator of transcription 6 (i.e., Stat6) VT transgenic mice that develop spontaneous atopic dermatitis-like disease that is dependent on T helper cell 2 cytokines and is associated with high serum concentrations of IgE. We observed that Stat6VT × Kit(W-sh/W-sh) mice developed more frequent and more severe allergic skin inflammation than Stat6VT transgenic mice that had mast cells. Together, these studies suggest that mast cells regulate epidermal barrier function and have a potential protective role in the development of atopic dermatitis-like disease.

Atopic dermatitis

Atopic dermatitis (also known as atopic eczema) is a chronic inflammatory skin disease that is characterised by intense itching and recurrent eczematous lesions. Although it most often starts in infancy and affects two of ten children, it is also highly prevalent in adults. It is the leading non-fatal health burden attributable to skin diseases, inflicts a substantial psychosocial burden on patients and their relatives, and increases the risk of food allergy, asthma, allergic rhinitis, other immune-mediated inflammatory diseases, and mental health disorders. Originally regarded as a childhood disorder mediated by an imbalance towards a T-helper-2 response and exaggerated IgE responses to allergens, it is now recognised as a lifelong disposition with variable clinical manifestations and expressivity, in which defects of the epidermal barrier are central. Present prevention and treatment focus on restoration of epidermal barrier function, which is best achieved through the use of emollients. Topical corticosteroids are still the first-line therapy for acute flares, but they are also used proactively along with topical calcineurin inhibitors to maintain remission. Non-specific immunosuppressive drugs are used in severe refractory cases, but targeted disease-modifying drugs are being developed. We need to improve understanding of the heterogeneity of the disease and its subtypes, the role of atopy and autoimmunity, the mechanisms behind disease-associated itch, and the comparative effectiveness and safety of therapies.

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

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

"Bringing Up Baby" to Tolerate Germs

How immune tolerance is maintained in the skin remains unclear. In this issue of Immunity, Rosenblum and colleagues demonstrate that tolerance to commensal bacteria is established during the neonatal period via regulatory T cells. Defining the crucial window during which commensal-specific tolerance is achieved has strategic implications for the induction of tolerance in allergic diseases.

Filaggrin genotype and skin diseases independent of atopic dermatitis in childhood

BACKGROUND

Filaggrin gene (FLG) mutations compromise skin barrier functions and increase risk of atopic dermatitis. We aimed to study effects on other skin diseases using unique data from the Danish registers.

METHODS

FLG genotyping of a population-based sample of 1547 children with extracted DNA and information on skin diseases from the Danish National Birth Cohort and Health Register, with 18 years follow-up during years 1996-2013. Odds ratios (OR) and hazard ratios (HR) were estimated using logistic regression and Cox regression, respectively, and adjusted for physician-diagnosed atopic dermatitis.

RESULTS

FLG mutations were associated with increased risk of dry skin (OR 1.9, CI 1.1-3.1), and a decreased risk of fungal skin infections at age <18 months (OR 0.2, CI 0.1-0.8). There was no association with wart treatments (HR 1.0, CI 0.6-1.7). FLG mutations were associated with an increased risk of atopic dermatitis (OR 3.3, CI 2.1-5.3), dermatology consultations for allergy or rash (HR 2.2, CI 1.4-3.5), basic dermatology consultations at age <5 years (HR 2.2, CI 1.7-2.9), urticaria at age <18 months (OR 2.9, CI 1.0-7.9), and other rash at age <18 months (OR 2.1, CI 1.2-3.8).

CONCLUSIONS

FLG mutations may predispose to skin disease in young children including urticaria, and rash not recognized as atopic dermatitis although equally frequent. In clinical practice, FLG genotyping may help indicate the use of moisturizers to reduce skin problems.

Retrospective Analysis on the Effects of House Dust Mite Specific Immunotherapy for More Than 3 Years in Atopic Dermatitis

PURPOSE

In extrinsic atopic dermatitis (AD), house dust mites (HDM) play a role in eliciting or aggravating allergic lesions. The nature of skin inflammation in AD has raised a growing interest in allergen-specific immunotherapy (SIT). Thus, we assessed clinical improvement and laboratory parameters for evaluation of the benefit of long-term SIT.

MATERIALS AND METHODS

A total of 217 AD patients who were treated with SIT for at least 3 years were retrospectively assessed, by using their investigator global assessment, pruritus scores, loss of sleep (LOS), total serum IgE, and eosinophil counts collected. Patients were additionally classified into subgroups according to age, initial AD severity and mono- or multi-sensitization to include different individual factors in the evaluation of SIT efficacy. Lastly, we compared laboratory data of good responders to SIT with that of poor responders to SIT.

RESULTS

Improvement after SIT therapy was observed in 192 out of 217 patients (88.4%). Among these patients, 138 (63.5%) achieved excellent, near-complete or complete clinical remission. Significant reduction of pruritus, LOS, and the mean value of total serum IgE were observed (p<0.01). Better outcome was found in patients younger than 12 years of age (p=0.024). Patients with moderate to severe AD showed better treatment outcomes (p=0.036). Patients sensitized only to HDM had the better response to treatment, but SIT was also effective in multi-sensitized groups (p=1.051). No significant differences in baseline laboratory results were observed between good and poor responders (p>0.05).

CONCLUSION

We emphasize the usefulness of long-term HDM SIT as a disease-modifying therapy for AD.

Sports activities enhance the prevalence of rhinitis symptoms in schoolchildren

BACKGROUND

To evaluate the association between sports activities and allergic symptoms, especially rhinitis, among schoolchildren.

METHODS

This longitudinal survey of schoolchildren collected data from questionnaires regarding allergic symptoms based on the International Study of Asthma and Allergies in Childhood (ISAAC) program and sports participation that were distributed to the parents of children at all 12 public primary schools in Ohmi-Hachiman City, Shiga Prefecture, Japan. Data were collected annually from 2011 until 2014, when the children reached 10 years of age. Blood samples were obtained in 2014, and the levels of immunoglobulin (Ig)E specific to four inhalant allergens were measured.

RESULTS

Data from 558 children were analyzed. At 10 years of age, prevalence of asthma and eczema did not differ significantly, while rhinitis was significantly higher (p = 0.009) among children who participated in sports. Prevalence of rhinitis increased as the frequency or duration of sports participation increased (p < 0.01). The prevalence of new-onset rhinitis increased significantly among 10-year-olds with increasing duration of participation in sports (p = 0.03). Among those who participated in continuous sports activities, the prevalence of rhinitis was significantly higher with prolonged eczema (p = 0.006). Sports activities did not increase sensitization to inhalant allergens.

CONCLUSION

Sports activities enhance the prevalence of rhinitis in schoolchildren. Prolonged eczema, together with sports participation, further promotes the symptoms. The mechanisms of these novel findings warrant further investigation.

Atopic eczema

Atopic eczema is an itchy inflammatory skin disease with a chronic relapsing-remitting course; it has increased in prevalence in recent decades and now affects up to 25% of school-aged children in the developed world and up to 10% of adults. Recent advances in understanding the aetiology of eczema have focused interest on skin barrier dysfunction as a common precursor and pathological feature. In addition, genetically determined skin barrier dysfunction (associated with mutations in the gene encoding filaggrin) is known to predispose to multiple systemic atopic diseases. First-line treatments for atopic eczema focus on maintaining and repairing the skin barrier (emollients) and reducing inflammation (topical steroids); allergen and irritant avoidance are also important to achieve disease control. Second and third-line treatments include topical calcineurin inhibitors, ultraviolet light and systemic immunosuppressant therapies of which only ciclosporin is licenced for the treatment of atopic eczema in adults. Novel biological therapies are in phase II-III clinical trials.

Chemokines, their receptors and human disease: the good, the bad and the itchy

Chemokines are a highly specialized group of cytokines that coordinate trafficking and homing of leucocytes between bone marrow, lymphoid organs and sites of infection or inflammation. They are also responsible for structural organization within lymphoid organs. Aberrant expression or function of these molecules, or their receptors, has been linked to protection or susceptibility to specific infectious diseases, as well as the risk of autoimmune disease and malignancy, revealing critical roles of chemokines and their receptors in human health, disease and therapeutics. In this review, we focus on human diseases that provide lessons regarding the critical role of these specialized and complex cytokines.

The role of innate lymphoid cells in healthy and inflamed skin

The skin constitutes the interface between the organism and the environment, and it protects the body from harmful substances in the environment via physical, chemical and immunological barriers. The immunological barrier of the skin comprises both cells from the innate and the adaptive immune system. During the last years, it has become clear that innate lymphoid cells play a role in homeostasis and inflammation of the skin in humans and mice. In this review, we will discuss the role of innate lymphoid cells in healthy and inflamed skin with special focus on their role in atopic dermatitis.

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

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

Transepidermal water loss measurement during infancy can predict the subsequent development of atopic dermatitis regardless of filaggrin mutations

BACKGROUND

Atopic dermatitis (AD) is characterized by skin barrier dysfunction. Few studies have used noninvasive techniques to measure epidermis function in asymptomatic neonates.

METHODS

Data of 116 infants from our previous randomized controlled study were analyzed. Skin barrier function was measured through transepidermal water loss (TEWL), stratum corneum hydration (SCH), and pH. The association between skin barrier function and time to AD development was evaluated. Patients were classified with high or low TEWL, and SCH and pH were assessed. The survival function of the time to AD development and hazard ratios were estimated. Allergic sensitization to egg white and ovomucoid at 32 weeks was assessed.

RESULTS

Regardless of a filaggrin mutation, TEWL (optimal cutoff, 6.5 g/m(2)/h) of the forehead within the first week of life showed a lower p-value than TEWL of the leg, and the SCH and pH measurements. Baseline TEWL of the forehead was not different between groups, except for the mean gestational age, and it was not affected by humidity. We found a significant difference in the cumulative AD incidence between the high and low TEWL groups for the forehead only (p < 0.05). The probability without AD was lower in the high TEWL group than in the low TEWL group. For only the high TEWL group, AD development decreased significantly with daily emollient use. The high TEWL group exhibited a higher rate of sensitization to ovomucoid (p = 0.07).

CONCLUSIONS

TEWL of the forehead during the first week of life is associated with AD development.

The Association between Atopic Disorders and Keloids: A Case-control Study

Background:

Keloids and atopic disorders share common inducing and maintaining inflammatory pathways that are characterized by T-helper cell 2 cytokines.

Aims and Objectives:

The objective of this study was to test for associations between keloids and atopic eczema, asthma and hay fever.

Materials and Methods:

This was a case-control study with 131 patients diagnosed with keloids at our dermatology outpatient clinic between 2000 and 2012. Controls were 258 partners of keloid or sarcoidosis patients. Patient who reported life time prevalences of atopic eczema, asthma and hay fever were assessed using a questionnaire based on The European Community Respiratory Health Survey (ECRHS) and The International Study of Asthma and Allergies in Children (ISAAC).

Results:

The prevalence of asthma was lower in keloid patients (19/131 vs. 20/258, P = 0.035), as was being diagnosed with asthma by a physician (18/131 vs. 19/258, P = 0.039) and using inhalators for asthma (13/131 vs. 7/258, P = 0.02). After adjusting for age and non-European descent the odds ratio for having a keloid was (adjusted OR = 4.44; 95% CI 1.59–12.40) in asthmatics using inhalators. There were no clear and consistent associations found for keloids with atopic eczema or with hay fever.

Conclusion:

In conclusion, our study shows that keloids may be strongly associated with atopic asthma. Atopic eczema and hay fever do not seem to be correlated with keloid. Further studies are warranted to assess the validity of atopic asthma as a risk factor for the development of keloid scars.

Genome-Wide Gene by Environment Interaction Analysis Identifies Common SNPs at 17q21.2 that Are Associated with Increased Body Mass Index Only among Asthmatics

Asthmatics have an increased risk of being overweight/obese. Although the underlying mechanisms of this are unclear, genetic factors are believed to play an essential role. To identify common genetic variants that are associated with asthma-related BMI increase, we performed a genome-wide gene by environment (asthma) interaction analysis for the outcome of BMI in the Multi-Ethnic Study of Atherosclerosis (MESA) study (N = 2474 Caucasians, 257 asthmatics), and replicated findings in the Framingham Heart Study (FHS) offspring cohort (N = 1408 Caucasians, 382 asthmatics). The replicable tagging SNP, rs2107212, was further examined in stratified analyses. Seven SNPs clustered in 17q21.2 were identified to be associated with higher BMI among asthmatics (interaction p < 5×10⁻⁷ in MESA and p < 0.05 in FHS). In both MESA and FHS asthmatics, subjects carrying the A allele on rs2107212 had significantly higher odds of obesity than non-carriers, which was not the case for non-asthmatics. We further examined BMI change subsequent to asthma diagnosis over a period of 26 years in FHS and demonstrated greater BMI increase among asthmatics compared to non-asthmatics. Asthmatics carrying the A allele at rs2107212 had significantly greater net BMI increase over the 26-year period compared to non-asthmatics. In this study, we found that common genetic variants on 17q21.2 are associated with post-asthma BMI increase among Caucasians. This finding will help elucidate pathways involved in the comorbidity of asthma and obesity.

Turning the inside out: the microbiology of atopic dermatitis

Allergy is on the rise worldwide. The hygiene hypothesis of atopic diseases linked microbes with atopic dermatitis (AD) both as drivers and modulators of skin pathology. The earlier literature favoured an inside-outside model of AD where an immunological abnormality compounded by a gut microbiota dysbiosis is the primary event. Probiotic intervention trials with lactobacilli and bifidobacteria as well as the application of bifidogenic oligosaccharide prebiotics showed indeed promising clinical results, but no consistent gut microbiota dysbiosis could be linked with AD. An alternative hypothesis known as outside-inside model of AD considers a genetic skin barrier effect compounded by a skin microbiota dysbiosis as primary pathogenic event. Cultivation microbiology has demonstrated strong skin colonization with superantigen-encoding Staphylococcus aureus in AD patients; microbiota and molecular microbiome analyses demonstrated that S. aureus abundance fluctuates and parallels clinical symptoms. In a mouse model, δ-toxin of S. aureus induced mast cell degranulation, leading to AD-like symptoms. Mutant mice developing AD symptoms showed increased skin colonization with S. aureus; antibiotic treatment alleviated the symptoms. Clinical trials showed that various treatments reducing S. aureus skin load also reduced AD symptoms, suggesting S. aureus as a potential critical driver of AD and a target for antimicrobial interventions other than antibiotics.

Pathophysiology of Food Allergy

Food allergy is a growing public health problem that is estimated to affect 4% to 8% of children and 5% of adults. In this review, we discuss our current understanding of the pathophysiology of food allergy, from oral tolerance, to sensitization, and lastly the elicitation of an allergic response. As much of the existing evidence for the mechanisms of food allergy is derived from animal models, we include these studies where relevant. In addition, whenever possible, we review similar evidence involved in human disease and provide applications for consideration in clinical practice.

Genetic associations and shared environmental effects on the skin microbiome of Korean twins

Background

The skin is the outermost layer of the human body and one of the key sites for host-microbe interactions. Both environmental and host genetic factors influence microbial communities in distinct anatomical niches, but little is known about their interplay in shaping the skin microbiome. Here, we investigate the heritable components of the skin microbiome and their association with host genetic factors.

Results

Based on our analysis of the microbiota from 45 individuals including monozygotic and dizygotic twins aged 26–55 years and their mothers, we found that skin microbial diversity was significantly influenced by age and skin pigmentation. Heritability analysis revealed genetic and shared environmental impacts on the skin microbiome. Furthermore, we observed a strong association between the abundance of Corynebacterium jeikeium and single nucleotide polymorphisms (SNPs) in the host FLG gene related to epidermal barrier function.

Conclusion

This study reveals an intimate association of the human skin microbiome and host genes, and increases our understanding of the role of human genetic factors in establishing a microbial ecosystem on the body surface.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2131-y) contains supplementary material, which is available to authorized users.

Advances in understanding and managing atopic dermatitis

Atopic dermatitis is a chronic, pruritic skin disease characterized by an improperly functioning skin barrier and immune dysregulation. We review proposed atopic dermatitis pathomechanisms, emphasizing how these impact current perspectives on natural history, role of allergic sensitization, and future therapeutic targets.

Epicutaneous immunotherapy for food allergy as a novel pathway for oral tolerance induction

Epicutaneous immunotherapy is a developing technique, aiming at desensitizing patients with food allergy with less risks that oral ingestion or injection could generate. Several clinical trials have been performed and are currently running, in milk and peanut allergy, assessing the safety of the technique and its efficacy. Preclinical models indicate a major role in the mechanisms of desensitization, for example, Tregs and epigenetic modifications.

Multi-ancestry genome-wide association study of 21,000 cases and 95,000 controls identifies new risk loci for atopic dermatitis

Genetic association studies have identified 21 loci associated with atopic dermatitis risk predominantly in populations of European ancestry. To identify further susceptibility loci for this common complex skin disease, we performed a meta-analysis of >15 million genetic variants in 21,399 cases and 95,464 controls from populations of European, African, Japanese and Latino ancestry, followed by replication in 32,059 cases and 228,628 controls from 18 studies. We identified 10 novel risk loci, bringing the total number of known atopic dermatitis risk loci to 31 (with novel secondary signals at 4 of these). Notably, the new loci include candidate genes with roles in regulation of innate host defenses and T-cell function, underscoring the important contribution of (auto-)immune mechanisms to atopic dermatitis pathogenesis.

Investigation of Skin Barrier Functions and Allergic Sensitization in Patients with Hyper-IgE Syndrome

PURPOSE

Hyper-IgE syndrome (HIES) is a severe primary immunodeficiency, characterized by increased serum IgE levels as well as recurrent infections and atopic dermatitis (AD)-like skin lesions. AD is a chronic inflammatory skin disease with immunologic alterations (Th2-Th22 polarization) and characteristic skin barrier dysfunctions. Our aim was to investigate physicochemical skin barrier alterations and allergic sensitization in STAT3-HIES patients in order to explore whether skin barrier dysfunction can play a role in the eczematoid skin lesions in these patients.

METHODS

In our experiments STAT3 and FLG mutation analyses were performed in STAT3-HIES (n = 7) and AD (n = 49) patients. Laboratory parameters (LDH and Eos counts), immunologic alterations (Th17 cell counts), allergic sensitization (total and specific IgE levels, skin prick tests, and medical history records), skin barrier changes [transepidermal water loss (TEWL), skin pH], serum and stratum corneum thymic stromal lymphopoietin (TSLP) levels were also examined.

RESULTS

Impaired Th17 cell numbers, but normal physicochemical barrier functions, as well as serum and stratum corneum TSLP levels, were found in STAT3-HIES, while these parameters were significantly altered in AD patients. Allergic sensitization was detected in nearly all AD patients, while no signs of sensitization occurred in STAT3-HIES.

CONCLUSIONS

Our study demonstrated that the skin barrier functions of STAT3-HIES patients are not damaged and they differ significantly from the altered skin barrier functions of AD patients. A well-functioning physicochemical skin barrier may be one of the explanations on the contradiction between the extremely high total IgE levels and the lack of allergic sensitization in these patients. Our study underlines the importance of skin barrier in the development of allergic sensitization.

Microbiome and pediatric atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin condition with drastic impacts on pediatric health. The pathogenesis of this common disease is not well understood, and the complex role of the skin microbiome in the pathogenesis and progression of atopic dermatitis is being elucidated. Skin commensal organisms promote normal immune system functions and prevent the colonization of pathogens. Alterations in the skin microbiome may lead to increased Staphylococcus aureus colonization and atopic dermatitis progression. Despite the evidence for their important role, probiotics have not been deemed efficacious for the treatment of atopic dermatitis, although studies suggest that probiotics may be effective at preventing the development of atopic dermatitis when given to young infants. This review will cover the most recent published work on the microbiome and pediatric atopic dermatitis.

The Role of Skin Barrier in the Pathogenesis of Food Allergy

Food allergy is a serious public health problem with an increasing prevalence. Current management is limited to food avoidance and emergency treatment. Research into the pathogenesis of food allergy has helped to shape our understanding of how patients become sensitized to an allergen. Classically, food sensitization was thought to occur through the gastrointestinal tract, but alternative routes of sensitization are being explored, specifically through the skin. Damaged skin barrier may play a crucial role in the development of food sensitization. Better understanding of how patients initially become sensitized may help lead to the development of a safe and effective treatment for food allergies or better prevention strategies.

Hypothetical Atopic Dermatitis-Myeloproliferative Neoplasm Syndrome

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Myeloproliferative neoplasms (MPNs) are hematopoietic malignancies caused by uncontrolled proliferation of hematopoietic stem/progenitor cells. Recent studies have described several mutant mice exhibiting both AD-like skin inflammation and MPN. Common pathways for skin inflammation encompass overexpression of thymic stromal lymphopoietin and reduced signaling of epidermal growth factor receptor in the epidermis, while overproduction of granulocyte-colony-stimulating factor by keratinocytes and constitutive activation of Stat5 in hematopoietic stem cells are important for the development of MPN. The murine studies suggest the existence of a similar human disease tentatively termed as the atopic dermatitis-myeloproliferative neoplasm syndrome.

Spontaneous atopic dermatitis is mediated by innate immunity, with the secondary lung inflammation of the atopic march requiring adaptive immunity

Background

Atopic dermatitis (AD) is an inflammatory skin condition that can occur in early life, predisposing to asthma development in a phenomenon known as the atopic march. Although genetic and environmental factors are known to contribute to AD and asthma, the mechanisms underlying the atopic march remain poorly understood. Filaggrin loss-of-function mutations are a major genetic predisposer for the development of AD and progression to AD-associated asthma.

Objective

We sought to experimentally address whether filaggrin mutations in mice lead to the development of spontaneous eczematous inflammation and address the aberrant immunologic milieu arising in a mouse model of filaggrin deficiency.

Methods

Filaggrin mutant mice were generated on the proallergic BALB/c background, creating a novel model for the assessment of spontaneous AD-like inflammation. Independently recruited AD case collections were analyzed to define associations between filaggrin mutations and immunologic phenotypes.

Results

Filaggrin-deficient mice on a BALB/c background had profound spontaneous AD-like inflammation with progression to compromised pulmonary function with age, reflecting the atopic march in patients with AD. Strikingly, skin inflammation occurs independently of adaptive immunity and is associated with cutaneous expansion of IL-5–producing type 2 innate lymphoid cells. Furthermore, subjects with filaggrin mutations have an increased frequency of type 2 innate lymphoid cells in the skin in comparison with control subjects.

Conclusion

This study provides new insights into our understanding of the atopic march, with innate immunity initiating dermatitis and the adaptive immunity required for subsequent development of compromised lung function.

Alternative, Complementary, and Forgotten Remedies for Atopic Dermatitis

Atopic dermatitis, perhaps more than other dermatologic diseases, has garnered much attention in the realm of alternative medicine. This may be because its etiopathogenesis is incompletely understood, it is increasingly common, and it waxes and wanes often without clear precipitants, opening up many opportunities for misinterpretation. Herein we explore the evidence for a number of different alternative and complementary therapies, from textiles to vitamin supplements. By definition, none have enough data to be deemed "effective" in a conventional sense, but it is hopeful that some show promising evidence that may one day lead to mainstream acceptance with further research.

Past, present, and future for biologic intervention in atopic dermatitis

Atopic dermatitis (AD) is a debilitating disease that significantly alters the quality of life for one in four children and one in 10 adults. Current management of AD utilizes combinations of treatments to symptomatically alleviate disease by suppressing the inflammatory response and restoring barrier function in the skin, reducing disease exacerbation and flare, and preventing secondary skin infections. Resolution is temporary and long-term usage of these treatments can be associated with significant side-effects. Antibody therapies previously approved for inflammatory diseases have been opportunistically evaluated in patients with atopic dermatitis; however, they often failed to demonstrate a significant clinical benefit. Monoclonal antibodies currently in development offer hope to those individuals suffering from the disease by specifically targeting immune and molecular pathways important for the pathogenesis of atopic dermatitis. Here, we review the underlying biological pathways and the state of the art in therapeutics in AD.

IL-25 and IL-33 Contribute to Development of Eosinophilic Airway Inflammation in Epicutaneously Antigen-Sensitized Mice

BACKGROUND

IL-25, IL-33 and TSLP are produced predominantly by epithelial cells and are known to induce Th2-type cytokines. Th2-type cytokines are involved not only in host defense against nematodes, but also in the development of Th2-type allergic diseases. TSLP was reported to be crucial for development of allergic airway inflammation in mice after inhalation of allergens to which they had been sensitized epicutaneously (EC) beforehand. However, the roles of IL-25 and IL-33 in the setting remain unclear.

METHODS

Mice deficient in IL-25 and IL-33 were sensitized EC with ovalbumin (OVA) and then challenged intranasally with OVA. Airway inflammation, the number of inflammatory cells in bronchoalveolar lavage fluids (BALFs) and airway hyperresponsiveness (AHR) in the mice were determined, respectively, by histological analysis, with a hemocytometer, and by using plethysmograph chambers with a ventilator. Expression of mRNA in the skin and lungs was determined by quantitative PCR, while the BALF levels of myeloperoxidase (MPO) and eosinophil peroxidase (EPO) and the serum levels of IgE were determined by ELISA.

RESULTS

Normal OVA-specific Th2- and Th17-cell responses of lymph nodes and spleens were observed in IL-25-deficient (IL-25-/-) and IL-33-/- mice after EC sensitization with OVA. Nevertheless, the number of eosinophils, but not neutrophils, in the BALFs, and the levels of Th2 cytokines, but not Th17 cytokines, in the lungs were significantly decreased in the IL-25-/- and IL-33-/- mice pre-sensitized EC with OVA, followed by inhalation of OVA, whereas their levels of AHR and OVA-specific serum IgE were normal.

CONCLUSIONS

Both IL-25 and IL-33 are critical for induction of Th2-type cytokine-mediated allergic airway eosinophilia, but not Th17-type cytokine-mediated airway neutrophilia, at the local sites of lungs in the challenge phase of mice sensitized EC with OVA. They do not affect OVA-specific T-cell induction in the sensitization phase.

Alternative, Complementary, and Forgotten Remedies for Atopic Dermatitis

Atopic dermatitis, perhaps more than other dermatologic diseases, has garnered much attention in the realm of alternative medicine. This may be because its etiopathogenesis is incompletely understood, it is increasingly common, and it waxes and wanes often without clear precipitants, opening up many opportunities for misinterpretation. Herein we explore the evidence for a number of different alternative and complementary therapies, from textiles to vitamin supplements. By definition, none have enough data to be deemed “effective” in a conventional sense, but it is hopeful that some show promising evidence that may one day lead to mainstream acceptance with further research.