DAMP molecules S100A9 and S100A8 activated by IL-17A and house-dust mites are increased in atopic dermatitis

Early skin inflammatory biomarker is predictive of development and persistence of atopic dermatitis in infants

BACKGROUND

The Short-Term Topical Application for Prevention of Atopic Dermatitis (STOP AD) study, a randomized, open-label trial evaluating the effect of short-term (from the first 4 postnatal days to age 8 weeks) skin barrier protection using Aveeno Dermexa Fast & Long-Lasting Balm (Johnson & Johnson, New Brunswick, NJ) in infants with a parent with allergic disease, demonstrated decreased cumulative incidence and decreased prevalence of atopic dermatitis (AD) at age 12 months.

OBJECTIVE

In the STOP AD study, we aimed to identify skin biomarkers that are associated with risk of development of AD.

METHODS

Skin swabs were collected from the cheek and antecubital fossa (AF) at baseline, age 8 weeks, and age 12 months from subsets of study participants from the intervention arm (n = 43 of 119) and control arm (n = 43 of 138) and were analyzed for specific cytokines (CCL27, CXCL2, human β-defensin-1 [hBD-1], IL-18, IL-8, IL-1α, IL-1 receptor antagonist [IL-1RA], IL-1β, S100A8/9, and IL-36γ) by ELISA.

RESULTS

Higher titers of S100A8/9 at the AF at age 8 weeks in infants with the filaggrin wild-type genotype (FLGwt), but not in those with filaggrin loss-of-function mutation (FLGmut), predicted (1) development of AD in the first year of life (P = .033), (2) presence of AD at ages 6 or 12 months (P = .009 and .035, respectively), (3) persistence of AD between ages 6 and 12 months (P < .001), and (4) development of AD with the emollient intervention.

CONCLUSION

Increased titers of S100A8/9 from skin swabs of the AF in high-risk infants at age 8 weeks with FLGwt were predictive of AD development in the first year of life and other AD features. These findings suggest that there are different molecular pathways leading to AD in individuals with FLGmut and in individuals with FLGwt. Early identification of infants who are likely to develop AD will allow more targeted interventions.

Biomarkers for phenotype-endotype relationship in atopic dermatitis: a critical review

Atopic dermatitis (AD) is the most common form of chronic skin inflammation with diverse clinical variants. Historically, various AD phenotypes have been grouped together without considering their heterogeneity. This approach has resulted in a lack of phenotype- and endotype-adapted therapeutic strategies. Comprehensive insights into AD pathogenesis have enabled precise medicinal approach for AD. These efforts aimed to redefine the endophenotype of AD and develop various biomarkers for diverse purposes. Among these endeavours, efforts are underway to elucidate the mechanisms (and related biomarkers) that lead to the emergence and progression of atopic diseases originating from AD (e.g., atopic march). This review focuses on diverse AD phenotypes and calls for a definition of endophenotypes. While awaiting scientific validation, these biomarkers ensure predicting disease onset and trajectory and tailoring therapeutic strategies for the future.

S100a6 knockdown promotes the differentiation of dental epithelial cells toward the epidermal lineage instead of the odontogenic lineage

Tooth development is a complex process involving various signaling pathways and genes. Recent findings suggest that ion channels and transporters, including the S100 family of calcium-binding proteins, may be involved in tooth formation. However, our knowledge in this regard is limited. Therefore, this study aimed to investigate the expression of S100 family members and their functions during tooth formation. Tooth germs were extracted from the embryonic and post-natal mice and the expression of S100a6 was examined. Additionally, the effects of S100a6 knockdown and calcium treatment on S100a6 expression and the proliferation of SF2 cells were examined. Microarrays and single-cell RNA-sequencing indicated that S100a6 was highly expressed in ameloblasts. Immunostaining of mouse tooth germs showed that S100a6 was expressed in ameloblasts but not in the undifferentiated dental epithelium. Additionally, S100a6 was localized to the calcification-forming side in enamel-forming ameloblasts. Moreover, siRNA-mediated S100a6 knockdown in ameloblasts reduced intracellular calcium concentration and the expression of ameloblast marker genes, indicating that S100a6 is associated with ameloblast differentiation. Furthermore, S100a6 knockdown inhibited the ERK/PI3K signaling pathway, suppressed ameloblast proliferation, and promoted the differentiation of the dental epithelium toward epidermal lineage. Conclusively, S100a6 knockdown in the dental epithelium suppresses cell proliferation via calcium and intracellular signaling and promotes differentiation of the dental epithelium toward the epidermal lineage.

Genome-wide identification of dysregulated alternative splicing and RNA-binding proteins involved in atopic dermatitis

Objectives: We explored the role and molecular mechanisms of RNA-binding proteins (RBPs) and their regulated alternative splicing events (RASEs) in the pathogenesis of atopic dermatitis (AD). Methods: We downloaded RNA-seq data (GSE121212) from 10 healthy control skin samples (healthy, Ctrl), 10 non-lesional skin samples with AD damage (non-lesional, NL), and 10 lesional skin samples with AD damage (lesional, LS). We performed the analysis of differentially expressed genes (DEGs), differentially expressed RBPs (DE-RBPs), alternative splicing (AS), functional enrichment, the co-expression of RBPs and RASEs, and quantitative polymerase chain reaction (qPCR). Results: We identified 60 DE-RBP genes by intersecting 2141 RBP genes from existing reports with overall 2697 DEGs. Most of the DE-RBP genes were found to be upregulated in the AD LS group and related to immune and apoptosis pathways. We observed different ASEs and RASEs among the healthy, AD NL, and AD LS groups. In particular, alt3p and alt5p were the main ASEs and RASEs in AD NL and AD LS groups, compared to the healthy group. Furthermore, we constructed co-expression networks of DE-RBPs and RAS, with particular enrichment in biological pathways including cytoskeleton organization, inflammation, and immunity. Subsequently, we selected seven genes that are commonly present in these three pathways to assess their expression levels in the peripheral blood mononuclear cells (PBMCs) from both healthy individuals and AD patients. The results demonstrated the upregulation of four genes (IFI16, S100A9, PKM, and ENO1) in the PBMCs of AD patients, which is highly consistent with DE-RBP genes analysis. Finally, we selected four RAS genes regulated by RBPs that were related to immune pathways and examined their RASEs in PBMCs from both AD patients and healthy controls. The results revealed an increased percentage of RASEs in the DDX60 gene in AD, which is highly consistent with AS analysis. Conclusion: Dysregulated RBPs and their associated RASEs may have a significant regulatory role in the development of AD and could be potential therapeutic targets in the future.

Single-cell profiling of prurigo nodularis demonstrates immune-stromal crosstalk driving profibrotic responses and reversal with nemolizumab

BACKGROUND

Prurigo nodularis (PN) is a chronic neuroimmune skin disease characterized by bilaterally distributed pruritic hyperkeratotic nodules on extremities and trunk. Neuroimmune dysregulation and chronic scratching are believed to both induce and maintain the characteristic lesions.

OBJECTIVES

This study sought to provide a comprehensive view of the molecular pathogenesis of PN at the single-cell level to identify and outline key pathologic processes and the cell types involved. Features that distinguish PN skin from the skin of patients with atopic dermatitis were of particular interest. We further aimed to determine the impact of the IL31RA antagonist, nemolizumab, and its specificity at the single-cell level.

METHODS

Single-cell RNA-sequencing of skin from 15 healthy donors and nonlesional and lesional skin from 6 patients each with PN and atopic dermatitis, combined with spatial-sequencing using the 10x Visium platform. Integration with bulk RNA-sequencing data from patients treated with nemolizumab.

RESULTS

This study demonstrates that PN is an inflammatory skin disease characterized by both keratinocyte proliferation and activation of profibrotic responses. This study also demonstrates that the COL11A1+ fibroblast subset is a major contributor to fibrosis and is predominantly found in the papillary dermis of PN skin. Activation of fibrotic responses is the main distinguishing feature between PN and atopic dermatitis skin. This study further shows the broad effect of nemolizumab on PN cell types, with a prominent effect driving COL11A1+ fibroblast and keratinocyte responses toward normal.

CONCLUSIONS

This study provides a high-resolution characterization of the cell types and cellular processes activated in PN skin, establishing PN as a chronic fibrotic inflammatory skin disease. It further demonstrates the broad effect of nemolizumab on pathological processes in PN skin.

DNA Methylation of the IL-17A Gene Promoter Is Associated with Subclinical Atherosclerosis and Coronary Artery Disease: The Genetics of Atherosclerotic Disease Mexican Study

The interleukin-17 (IL-17) has a crucial role during inflammation and has been associated with cardiovascular diseases, but its role in epigenetics is still poorly understood. Therefore, the aim of this study was to evaluate the DNA methylation status of the IL-17A gene promoter to establish whether it may represent a risk factor for subclinical atherosclerosis (SA) or clinical coronary artery disease (CAD). We included 38 patients with premature CAD (pCAD), 48 individuals with SA, and 43 healthy controls. Methylation in the CpG region of the IL-17A gene promoter was assessed via methylation-specific polymerase chain reaction (MSP). Individuals with SA showed increased methylation levels compared to healthy controls and pCAD patients, with p < 0.001 for both. Logistic regression analysis showed that high methylation levels represent a significant risk for SA (OR = 5.68, 95% CI = 2.38-14.03, p < 0.001). Moreover, low methylation levels of the IL-17A gene promoter DNA represent a risk for symptomatic pCAD when compared with SA patients (OR = 0.16, 95% CI = 0.06-0.41, p < 0.001). Our data suggest that the increased DNA methylation of the IL-17A gene promoter is a risk factor for SA but may be a protection factor for progression from SA to symptomatic CAD.

Periostin C-Terminal Is Intrinsically Disordered and Interacts with 143 Proteins in an In Vitro Epidermal Model of Atopic Dermatitis

Human periostin is a 78-91 kDa matricellular protein implicated in extracellular matrix remodeling, tumor development, metastasis, and inflammatory diseases like atopic dermatitis, psoriasis, and asthma. The protein consists of six domains, including an N-terminal Cys-rich CROPT domain, four fasciclin-1 domains, and a C-terminal domain. The exons encoding the C-terminal domain may be alternatively spliced by shuffling four exons, generating ten variants of unknown function. Here, we investigate the structure and interactome of the full-length variant of the C-terminal domain with no exons spliced out. The structural analysis showed that the C-terminal domain lacked a tertiary structure and was intrinsically disordered. In addition, we show that the motif responsible for heparin-binding is in the conserved very C-terminal part of periostin. Pull-down confirmed three known interaction partners and identified an additional 140 proteins, among which nine previously have been implicated in atopic dermatitis. Based on our findings, we suggest that the C-terminal domain of periostin facilitates interactions between connective tissue components in concert with the four fasciclin domains.

Skin surface biomarkers are associated with future development of atopic dermatitis in children with family history of allergic disease

BACKGROUND

Atopic dermatitis (AD) is a common childhood chronic inflammatory skin disorder that can significantly impact quality of life and has been linked to the subsequent development of food allergy, asthma, and allergic rhinitis, an association known as the "atopic march."

OBJECTIVE

The aim of this study was to identify biomarkers collected non-invasively from the skin surface in order to predict AD before diagnosis across a broad age range of children.

METHODS

Non-invasive skin surface measures and biomarkers were collected from 160 children (3-48 months of age) of three groups: (A) healthy with no family history of allergic disease, (B) healthy with family history of allergic disease, and (C) diagnosed AD.

RESULTS

Eleven of 101 children in group B reported AD diagnosis in the subsequent 12 months following the measurements. The children who developed AD had increased skin immune markers before disease onset, compared to those who did not develop AD in the same group and to the control group. In those enrolled with AD, lesional skin was characterized by increased concentrations of certain immune markers and transepidermal water loss, and decreased skin surface hydration.

CONCLUSIONS

Defining risk susceptibility before onset of AD through non-invasive methods may help identify children who may benefit from early preventative interventions.

Gene signature from cutaneous autoimmune diseases provides potential immunotherapy-relevant biomarkers in melanoma

Immune checkpoint inhibitors (ICIs) are promising agents for treating melanoma. Given that autoimmune skin diseases exhibit hyper immune reaction, investigation of immune cells from autoimmune skin disease is crucial to validate the effectiveness of ICIs in melanoma treatment. We employed multipanel markers to predict the response to immune checkpoint inhibitors by characterizing the gene expression signatures of skin immune cells in systemic lupus erythematosus (SLE), atopic dermatitis (AD), and psoriasis (PS). By analyzing single-cell RNA sequencing data from each dataset, T cell gene signatures from autoimmune skin diseases exhibit a complex immune response in tumors that responded to immunotherapy. Based on that CD86 and CD80 provide essential costimulatory signals for T cell activation, we observed that interaction of CD86 signaling has been enhanced in the T cells of patients with SLE, AD, and PS. Our analysis revealed a common increase in CD86 signals from dendritic cells (DCs) to T cells in patients with SLE, AD, and PS, confirming that dendritic cells produce pro-inflammatory cytokines to activate T cells. Thus, we hypothesize that T cell gene signatures from autoimmune skin diseases exhibit a pro-inflammatory response and have the potential to predict cancer immunotherapy. Our study demonstrated that T cell gene signatures derived from inflammatory skin diseases, particularly SLE and PS, hold promise as potential biomarkers for predicting the response to immune checkpoint blockade therapy in patients with melanoma. Our data provide an understanding of the immune-related characteristics and differential gene expression patterns in autoimmune skin diseases, which may represent promising targets for melanoma immunotherapy.

Crisaborole Inhibits Itch and Pain by Preventing Neutrophil Infiltration in a Mouse Model of Atopic Dermatitis

Crisaborole, a phosphodiesterase 4 (PDE4) inhibitor, has been approved for the treatment of mild to moderate atopic dermatitis. Atopic dermatitis is often associated with increased pain. Using a mouse model, this study investigated whether crisaborole suppresses pain associated with atopic dermatitis and the potential mechanisms underlying it. The mouse model for atopic dermatitis was developed by repeatedly applying MC903. MC903-treated mice had increased spontaneous scratching (itch-related behaviour) and wiping behaviour (pain-related behaviour). Crisaborole was topically applied to the cheek skin of MC903-treated mice, and it reduced both itch- and pain-related behaviours in these mice. Immunofluorescence staining revealed that crisaborole reduced neutrophil infiltration and interaction of neutrophils with sensory neurones. Intradermal injection of S100A8/A9, proinflammatory neutrophil mediator, enhanced not only itch-related behaviours evoked by histamine or chloroquine, but also pain-related behaviours evoked by capsaicin. Calcium imaging of mouse dorsal root ganglion neurones revealed that pretreatment with S100A8/A9 significantly increased calcium responses to histamine and capsaicin, and the proportion of chloroquine-sensitive neurones. These findings suggest that the PDE4 inhibitor reduces itch and pain, in part by inhibiting infiltration of S100A8/A9-containing neutrophils in a mouse model of MC903-induced atopic dermatitis.

IL-17A exacerbates psoriasis in a STAT3 overexpressing mouse model

Background

Psoriasis is an autoimmune skin disease characterized by immunocyte activation, excessive proliferation, and abnormal differentiation of keratinocytes. Signal transducers and activators of transcription 3 (STAT3) play a crucial role in linking activated keratinocytes and immunocytes during psoriasis development. T helper (Th) 17 cells and secreted interleukin (IL)-17A contribute to its pathogenesis. IL-17A treated STAT3 overexpressing mouse model might serve as an animal model for psoriasis.

Methods

In this study, we established a mouse model of psoriasiform dermatitis by intradermal IL-17A injection in STAT3 overexpressing mice. Transcriptome analyses were performed on the skin of wild type (WT), STAT3, and IL-17A treated STAT3 mice. Bioinformatics-based functional enrichment analysis was conducted to predict biological pathways. Meanwhile, the morphological and pathological features of skin lesions were observed, and the DEGs were verified by qPCR.

Results

IL-17A treated STAT3 mice skin lesions displayed the pathological features of hyperkeratosis and parakeratosis. The DEGs between IL-17A treated STAT3 mice and WT mice were highly consistent with those observed in psoriasis patients, including S100A8, S100A9, Sprr2, and LCE. Gene ontology (GO) analysis of the core DEGs revealed a robust immune response, chemotaxis, and cornified envelope, et al. The major KEGG enrichment pathways included IL-17 and Toll-like receptor signaling pathways.

Conclusion

IL-17A exacerbates psoriasis dermatitis in a STAT3 overexpressing mouse.

S-100 Proteins: Basics and Applications as Biomarkers in Animals with Special Focus on Calgranulins (S100A8, A9, and A12)

S100 proteins are a group of calcium-binding proteins which received this name because of their solubility in a 100% saturated solution of ammonium sulphate. They have a similar molecular mass of 10-12 KDa and share 25-65% similarity in their amino acid sequence. They are expressed in many tissues, and to date 25 different types of S100 proteins have been identified. This review aims to provide updated information about S100 proteins and their use as biomarkers in veterinary science, with special emphasis on the family of calgranulins that includes S100A8 (calgranulin A; myeloid-related protein 8, MRP8), S100A9 (calgranulin B; MRP14), and S100A12 (calgranulin C). The proteins SA100A8 and S100A9 can be linked, forming a heterodimer which is known as calprotectin. Calgranulins are related to the activation of inflammation and the immune system and increase in gastrointestinal diseases, inflammation and sepsis, immunomediated diseases, and obesity and endocrine disorders in different animal species. This review reflects the current knowledge about calgranulins in veterinary science, which should increase in the future to clarify their role in different diseases and potential as biomarkers and therapeutic targets, as well as the practical use of their measurement in non-invasive samples such as saliva or feces.

Gamma-delta (γδ) T cell-derived cytokines (IL-4, IL-17, IFN-γ and IL-10) and their possible implications for atopic dermatitis development

Atopic dermatitis (AD) is a chronic disease related to skin disorders that affect individuals in their childhood and can persist or start in adulthood. Patients affected by this disease commonly show skin lesions on the body surface (mainly on the upper and lower limbs) and allergic rhinitis or asthma crises. Looking at the disease from a molecular perspective, the major cytokines involved in inflammatory skin diseases, not only AD, include IL-4, IL-17, IFN-γ and IL-10. Although they can produce these cytokines and infiltrate the affected epithelia in patients with AD, γδ T cells are still almost unexplored. In this update, we briefly discuss the involvement of IL-4, IL-17, IFN-γ and IL-10 in the pathophysiology of AD and the possible role of γδ T cells during the inflammatory process.

Delayed type hypersensitivity reactions to various allergens may differently model inflammatory skin diseases

BACKGROUND

Treatment of inflammatory skin diseases, including atopic dermatitis (AD) and psoriasis, is undergoing transformative changes, highlighting the need to develop experimental models of skin inflammation in humans to predict treatment responses.

METHODS

We topically or intradermally administered four common sensitizers (dust mite (DM), diphencyprone (DPCP), nickel (Ni), and purified protein derivative (PPD)) to the backs of 40 healthy patients and the skin hypersensitivity response was biopsied and evaluated using immunohistochemistry, RNA-seq, and RT-PCR.

RESULTS

All agents induced strong increases in cellular infiltrates (T-cells and dendritic cells) as compared to untreated skin (p < .05), with variable T helper polarization. Overall, DPCP induced the strongest immune responses across all pathways, including innate immunity (IL-1α, IL-8), Th1 (IFNγ, CXCL10), Th2 (IL-5, CCL11), and Th17 (CAMP/LL37) products, as well as the highest regulatory tone (FOXP3, IL-34, IL-37) (FDR <0.01). Nickel induced Th17 (IL-17A), Th1 (CXCL10) and Th2 (IL-4R) immune responses to a lesser extent than DPCP (p < .05). PPD induced predominantly Th1 (IFNγ, CXCL10, STAT1) and Th17 inflammation (IL-17A) (p < .05). DM induced modulation of Th2 (IL-13, CCL17, CCL18), Th22 (IL-22), and Th17/Th22 (S100A7/9/12) pathways (p < .05). Barrier defects that characterize both AD and psoriasis were best modeled by DPCP and Ni, followed by PPD, including downregulation of terminal differentiation (FLG, FLG2, LOR, LCEs), tight junction (CLDN1/CLDN8), and lipid metabolism (FA2H, FABP7)-related markers.

CONCLUSION

Our data imply that DPCP induced the strongest immune response across all pathways, and barrier defects characteristic of AD and psoriasis.

Topical Skullcapflavone II attenuates atopic dermatitis in a mouse model by directly inhibiting associated cytokines in different cell types

Skullcapflavone II (SFII), a flavonoid derived from Scutellaria baicalensis, is an anticancer agent. We aimed to validate SFII for atopic dermatitis (AD) therapy by demonstrating the anti-inflammatory effects of SFII in an AD mouse model produced by the topical application of the vitamin D3 analog MC903. We showed that topical treatment with SFII significantly suppressed MC903-induced serum IgE levels compared with topical hydrocortisone (HC) treatment. Topical SFII also prevents MC903-induced pruritus, skin hyperplasia, and inflammatory immune cell infiltration into lesional skin comparable to topical HC. In addition, MC903-induced immune cell chemoattractants and AD-associated cytokine production in skin lesions were effectively suppressed by topical SFII. The production of MC903-induced effector cytokines influencing T helper (Th)2 and Th17 polarization in lesioned skin is significantly inhibited by topical SFII. Furthermore, we showed that SFII can directly inhibit the production of AD-associated cytokines by human primary keratinocytes, mouse bone marrow-derived cells (BMDCs), and mouse CD4⁺ T cells in vitro. Lastly, we demonstrated that topical SFII more effectively suppressed serum IgE levels, the production of IL-4 and thymic stromal lymphopoietin (TSLP), and infiltration of CD4⁺ T cells and Gr-1⁺ cells (neutrophils) into lesion skin compared to topical baicalein (a flavonoid derived from Scutellaria baicalensis), which has anti-inflammatory effects. Taken together, our findings suggest that SFII may have promising therapeutic potential for this complex disease via the regulation of multiple AD-associated targets.

Annoying Psoriasis and Atopic Dermatitis: A Narrative Review

Skin is an important organ that mainly functions as a barrier. Skin diseases can damage a person's self-confidence and reduce their willingness to socialize, as well as their social behavior and willingness. When the skin appearance is abnormal, in addition to affecting the quality of life, it often leads to personal, social, and psychological dysfunction and even induces depression. Psoriasis and atopic dermatitis are common chronic skin diseases. Their prevalence in the world is 3-10%, and there is an increasing trend year by year. These congenital or acquired factors cause the dysfunction of the immune system and then destroy the barrier function of the skin. Because these patients are flooded with a variety of inflammatory mediators, this causes skin cells to be in chronic inflammation. Therefore, psoriasis and atopic dermatitis are also considered systemic chronic inflammatory diseases. In the healthcare systems of developed countries, it is unavoidable to spend high costs to relieve symptoms of psoriasis and atopic dermatitis patients, because psoriasis and atopic dermatitis have a great influence on individuals and society. Giving a lot of attention and developing effective treatment methods are the topics that the medical community must work on together. Therefore, we used a narrative review manuscript to discuss pathogenesis, clinical classification, incidence, and treatment options, including topical medication, systemic therapeutics, immunosuppressive medication for psoriasis, and atopic dermatitis, as well as also comparing the differences between these two diseases. We look forward to providing readers with comprehensive information on psoriasis and atopic dermatitis through this review article.

A review of the mechanisms of keratinocytes damage caused by Staphylococcus aureus infection in patients with atopic dermatitis

The dysregulation of skin microflora in patients with atopic dermatitis (AD) has become a research hotspot in recent years. Metagenomic studies have shown that microbial diversity is decreased, whereas the Staphylococcus aureus infection is increased in AD. Keratinocytes are the primary barrier against the invasion of external pathogenic microorganisms. Staphylococcus aureus infection can abnormally activate innate and adaptive immune responses in keratinocytes, resulting in a vicious cycle between Staphylococcus aureus infection and AD. This article reviews the mechanisms of inflammatory damage of keratinocytes induced by Staphylococcus aureus infection in patients with AD, providing a theoretical basis for the study of new targeted drugs. This review also suggests for the management of Staphylococcus aureus infection in patients with AD.

Stratum corneum levels of calprotectin proteins S100A8/A9 correlate with disease activity in psoriasis patients

Psoriasis is an intractable inflammatory skin disorder characterized by scaly erythema and plaques. The Psoriasis Area and Severity Index (PASI) is widely used to score disease severity, but evaluation is subjective, and an objective biomarker would be useful. The stratum corneum (SC), which can be non-invasively harvested, may reflect psoriasis-associated changes in epidermal keratinocytes, such as the upregulation of the calprotectin proteins S100A8 and S100A9. The aim of this study was to examine the availability of S100A8/A9 protein levels in SC as a biomarker of psoriasis disease activity. Fifty-three patients with psoriasis, 30 with psoriasis vulgaris (PsV), and 23 with psoriatic arthritis (PsA) participated. SC cells from lesional and non-lesional skin were collected by tape-stripping. S100A8/A9 levels in serum and in SC were quantified by enzyme-linked immunosorbent assay and compared with PASI score before and after treatment initiation or switching. Atopic dermatitis (AD) patients and disease-free individuals were used as controls. Expression of S100A8/A9 in SC of lesional skin of psoriasis patients was significantly higher than in non-lesional skin or AD skin. There was no significant difference of SC S100A8/A9 levels between PsV and PsA patients. The S100A8/A9 levels in SC of psoriasis patients were significantly positively correlated with the PASI score. When patients' skin lesions cleared (PASI clear) in response to treatment, expression of S100A8/A9 in SC was no longer detectable. S100A8/A9 protein levels in SC may be available as an objective, non-invasive biomarker of psoriasis activity to complement PASI scoring.

Gut microbiota restoration through fecal microbiota transplantation: a new atopic dermatitis therapy

The pathogenesis of atopic dermatitis (AD) involves complex factors, including gut microbiota and immune modulation, which remain poorly understood. The aim of this study was to restore gut microbiota via fecal microbiota transplantation (FMT) to ameliorate AD in mice. FMT was performed using stool from donor mice. The gut microbiota was characterized via 16S rRNA sequencing and analyzed using Quantitative Insights into Microbial Ecology 2 with the DADA2 plugin. Gut metabolite levels were determined by measuring fecal short-chain fatty acid (SCFA) contents. AD-induced allergic responses were evaluated by analyzing blood parameters (IgE levels and eosinophil percentage, eosinophil count, basophil percentage, and monocyte percentage), the levels of Th1 and Th2 cytokines, dermatitis score, and the number of mast cells in the ileum and skin tissues. Calprotectin level was measured to assess gut inflammation after FMT. FMT resulted in the restoration of gut microbiota to the donor state and increases in the levels of SCFAs as gut metabolites. In addition, FMT restored the Th1/Th2 balance, modulated Tregs through gut microbiota, and reduced IgE levels and the numbers of mast cells, eosinophils, and basophils. FMT is associated with restoration of gut microbiota and immunologic balance (Th1/Th2) along with suppression of AD-induced allergic responses and is thus a potential new therapy for AD.

Cutaneous barrier dysfunction in allergic diseases

The fundamental defect(s) that drives atopic dermatitis (AD) remains controversial. "Outside in" proponents point to the important association of filaggrin gene mutations and other skin barrier defects with AD. The "inside out" proponents derive support from evidence that AD occurs in genetic animal models with overexpression of type 2 immune pathways in their skin, and humans with gain-of-function mutations in their type 2 response develop severe AD. The observation that therapeutic biologics, targeting type 2 immune responses, can reverse AD provides compelling support for the importance of "inside out" mechanisms of AD. In this review, we propose a central role for epithelial cell dysfunction that accounts for the dual role of skin barrier defects and immune pathway activation in AD. The complexity of AD has its roots in the dysfunction of the epithelial barrier that allows the penetration of allergens, irritants, and microbes into a cutaneous milieu that facilitates the induction of type 2 immune responses. The AD phenotypes and endotypes that result in chronic skin inflammation and barrier dysfunction are modified by genes, innate/adaptive immune responses, and different environmental factors that cause skin barrier dysfunction. There is also compelling evidence that skin barrier dysfunction can alter the course of childhood asthma, food allergy, and allergic rhinosinusitis. Effective management of AD requires a multipronged approach, not only restoring cutaneous barrier function, microbial flora, and immune homeostasis but also enhancing skin epithelial differentiation.

Skin-resident natural killer T cells participate in cutaneous allergic inflammation in atopic dermatitis

BACKGROUND

Natural killer T (NKT) cells are unconventional T cells that bridge innate and adaptive immunity. NKT cells have been implicated in the development of atopic dermatitis (AD).

OBJECTIVE

We aimed to investigate the role of NKT cells in AD development, especially in skin.

METHODS

Global proteomic and transcriptomic analyses were performed by using skin and blood from human healthy-controls and patients with AD. Levels of CXCR4 and CXCL12 expression in skin NKT cells were analyzed in human AD and mouse AD models. By using parabiosis and intravital imaging, the role of skin CXCR4⁺ NKT cells was further evaluated in models of mice with AD by using CXCR4-conditionally deficient or CXCL12 transgenic mice.

RESULTS

CXCR4 and its cognate ligand CXCL12 were significantly upregulated in the skin of humans with AD by global transcriptomic and proteomic analyses. CXCR4⁺ NKT cells were enriched in AD skin, and their levels were consistently elevated in our models of mice with AD. Allergen-induced NKT cells participate in cutaneous allergic inflammation. Similar to tissue-resident memory T cells, the predominant skin NKT cells were CXCR4⁺ and CD69⁺. Skin-resident NKT cells uniquely expressed CXCR4, unlike NKT cells in the liver, spleen, and lymph nodes. Skin fibroblasts were the main source of CXCL12. CXCR4⁺ NKT cells preferentially trafficked to CXCL12-rich areas, forming an enriched CXCR4⁺ tissue-resident NKT cells/CXCL12⁺ cell cluster that developed in acute and chronic allergic inflammation in our models of mice with AD.

CONCLUSIONS

CXCR4⁺ tissue-resident NKT cells may form a niche that contributes to AD, in which CXCL12 is highly expressed.

Immunophenotyping in pemphigus reveals a TH17/TFH17 cell-dominated immune response promoting desmoglein1/3-specific autoantibody production

BACKGROUND

T_H2 cells were thought to be a pivotal factor for initiation of the autoimmune blistering disease pemphigus. However, the role of other T-cell subsets in pemphigus pathogenesis remained unclear.

OBJECTIVE

We aimed to characterize the exact phenotype of T cells responsible for the development of pemphigus.

METHODS

Whole transcriptome shotgun sequencing was performed to determine differential gene expression in pemphigus lesions and skin of healthy individuals. The cutaneous cytokine signature was further evaluated by real-time quantitative PCR. In peripheral blood, the distribution of T_H cell and folliclular helper (T_FH) cell subsets was analyzed by flow cytometry. Finally, the capacity of T_H and T_FH cell subsets to induce desmoglein (Dsg)-specific autoantibodies by memory B cells was evaluated in coculture experiments.

RESULTS

Transcriptome analysis of skin samples identified an IL-17A-dominated immune signature in patients with pemphigus, and Kyoto Encyclopedia of Genes and Genomes pathway analysis confirmed the dominance of the IL-17A signaling pathway. Increased expression of IL17A and associated cytokines was also detected by real-time quantitative PCR comparing lesional with perilesional or healthy skin. Interestingly, utilization of flow cytometry showed that patients with active pemphigus had elevated levels of circulating IL-17⁺_, T_H17, T_FH17, and T_FH17.1 cells. Notably, levels of T_H17 and T_FH17 cells correlated with levels of Dsg-specific CD19⁺CD27⁺ memory B cells, and patients with acute pemphigus showed higher levels of Dsg3-autoreactive T_FH17 cells. Coculture experiments revealed T_FH17 cells as primarily responsible for inducing Dsg-specific autoantibody production by B cells.

CONCLUSION

Our findings show that T_FH17 cells are critically involved in the pathogenesis of pemphigus and offer novel targets for therapeutic intervention.

Effect of S100A8 and S100A9 on expressions of cytokine and skin barrier protein in human keratinocytes

Atopic dermatitis (AD) is an inflammatory skin disorder caused by immunological dysregulation and genetic factors. Whether the expression levels of cytokine and skin barrier protein were altered by S100 calcium binding protein A8 (S100A8) and S100A9 in human keratinocytic HaCaT cells was examined in the present study. Alterations of cytokine expression were examined by ELISA following treatment with S100A8/9 and various signal protein‑specific inhibitors. Activation of the mitogen activated protein kinase (MAPK) pathway and nuclear factor (NF)‑κB was evaluated by using western blotting and an NF‑κB activity test, respectively. The expression levels of interleukin (IL)‑6, IL‑8 and monocyte chemoattractant protein‑1 increased following treatment with S100A8 and S100A9, and the increase was significantly blocked by specific signaling pathway inhibitors, including toll‑like receptor 4 inhibitor (TLR4i), rottlerin, PD98059, SB203580 and BAY‑11‑7085. Extracellular signal‑regulated kinase (ERK) and p38 MAPK pathways were activated in a time‑dependent manner following treatment with S100A8 and S100A9. Phosphorylation of ERK and p38 MAPK were blocked by TLR4i and rottlerin. S100A8 and S100A9 induced translocation of NF‑κB in a time‑dependent manner, and the activation of NF‑κB was inhibited by TLR4i, rottlerin, PD98059 and SB203580. In addition, S100A8 and S100A9 decreased the expression of skin barrier proteins, filaggrin and loricrin. These results may help to elucidate the pathogenic mechanisms of AD and develop clinical strategies for controlling AD.

Epithelial barrier repair and prevention of allergy

Allergic diseases have in common a dysfunctional epithelial barrier, which allows the penetration of allergens and microbes, leading to the release of type 2 cytokines that drive allergic inflammation. The accessibility of skin, compared with lung or gastrointestinal tissue, has facilitated detailed investigations into mechanisms underlying epithelial barrier dysfunction in atopic dermatitis (AD). This Review describes the formation of the skin barrier and analyzes the link between altered skin barrier formation and the pathogenesis of AD. The keratinocyte differentiation process is under tight regulation. During epidermal differentiation, keratinocytes sequentially switch gene expression programs, resulting in terminal differentiation and the formation of a mature stratum corneum, which is essential for the skin to prevent allergen or microbial invasion. Abnormalities in keratinocyte differentiation in AD skin result in hyperproliferation of the basal layer of epidermis, inhibition of markers of terminal differentiation, and barrier lipid abnormalities, compromising skin barrier and antimicrobial function. There is also compelling evidence for epithelial dysregulation in asthma, food allergy, eosinophilic esophagitis, and allergic rhinosinusitis. This Review examines current epithelial barrier repair strategies as an approach for allergy prevention or intervention.

Upregulation of calprotectin in mild IgE-mediated ovalbumin hypersensitivity

Calprotectin, also known as S100A8/A9, has been linked to gut inflammation caused by IgE-mediated food hypersensitivities, but the pathophysiologic abnormalities it causes remain to be determined. We created a mild food hypersensitivity model through oral gavage of ovalbumin in Norway brown rats without using immune adjuvant. Changes in the levels of calprotectin and inflammation-associated cytokines were then observed over time. We found that fecal calprotectin as well as jejunal and liver TLR4, TNF-α, NF-κB, IL-1β, and IL-6 were upregulated in hypersensitive rats. Additionally, the influence of calprotectin on CD4⁺ T and dendritic cells was observed by co-culturing CD4⁺ T cells with dendritic cells, which revealed a shift toward increased Th2 T cells in calprotectin-treated cultures. These results suggest that calprotectin, along with other inflammatory factors, promotes the inflammation seen in mild food allergy.

A systematic review of the role of interleukin-17 and the interleukin-20 family in inflammatory allergic skin diseases

PURPOSE OF REVIEW

Allergic skin diseases include atopic dermatitis/eczema, contact dermatitis, and drug hypersensitivity. Allergic skin diseases have a high prevalence. Atopic dermatitis is one of the most common inflammatory skin diseases and similar for allergic rhinitis and allergic asthma. Over a long period, allergic diseases have been regarded as immunoglobulin E-mediated T-helper-2 (Th2)-driven. But new cytokines and T cells have been discovered within the last years. In this systematic review, the focus is laid on interleukin-17 (IL-17) and the interleukin-20 (IL-20) family which appear to be fine-tuning the Th2-driven answer.

RECENT FINDINGS

IL-17 is a proinflammatory cytokine, which is produced by T cells. Primarily, IL-17 is produced by activated CD4+ cells, called Th-17 cells. IL-17 regulates keratinocyte expression of adhesion molecules and chemokines. IL-17 is involved in the pathogenesis of inflammatory diseases as psoriasis, arthritis, and inflammatory bowel diseases. In allergic diseases, the involvement of the TH17/IL17-pathway has only been recently described. Regarding the IL-20 family, IL-22 is the most interesting and the most studied cytokine in terms of allergic inflammatory disorders. IL-22 is produced by T-helper 22 cells, a new subset of CD4+ cells.

SUMMARY

IL-17 as well as IL-22 seem to play a role in the pathogenesis of allergic skin diseases.

IL-17 Receptor A Maintains and Protects the Skin Barrier To Prevent Allergic Skin Inflammation

Atopic dermatitis (AD) is a common inflammatory skin disease affecting up to 20% of children and 3% of adults worldwide and is associated with dysregulation of the skin barrier. Although type 2 responses are implicated in AD, emerging evidence indicates a potential role for the IL-17A signaling axis in AD pathogenesis. In this study we show that in the filaggrin mutant mouse model of spontaneous AD, IL-17RA deficiency (Il17ra-/- ) resulted in severe exacerbation of skin inflammation. Interestingly, Il17ra-/- mice without the filaggrin mutation also developed spontaneous progressive skin inflammation with eosinophilia, as well as increased levels of thymic stromal lymphopoietin (TSLP) and IL-5 in the skin. Il17ra-/- mice have a defective skin barrier with altered filaggrin expression. The barrier dysregulation and spontaneous skin inflammation in Il17ra-/- mice was dependent on TSLP, but not the other alarmins IL-25 and IL-33. The associated skin inflammation was mediated by IL-5-expressing pathogenic effector Th2 cells and was independent of TCRγδ T cells and IL-22. An absence of IL-17RA in nonhematopoietic cells, but not in the hematopoietic cells, was required for the development of spontaneous skin inflammation. Skin microbiome dysbiosis developed in the absence of IL-17RA, with antibiotic intervention resulting in significant amelioration of skin inflammation and reductions in skin-infiltrating pathogenic effector Th2 cells and TSLP. This study describes a previously unappreciated protective role for IL-17RA signaling in regulation of the skin barrier and maintenance of skin immune homeostasis.

Cellular and molecular immunologic mechanisms in patients with atopic dermatitis

Atopic dermatitis (AD) is a complex skin disease frequently associated with other diseases of the atopic diathesis. Recent evidence supports the concept that AD can also recognize other comorbidities, such as chronic inflammatory bowel or cardiovascular diseases. These comorbidities might result from chronic cutaneous inflammation or from a common, yet-to-be-defined immunologic background leading to immune deviations. The activation of immune cells and their migration to the skin play an essential role in the pathogenesis of AD. In patients with AD, an underlying immune deviation might result in higher susceptibility of the skin to environmental factors. There is a high unmet medical need to define immunologic endotypes of AD because it has significant implications on upcoming stratification of the phenotype of AD and the resulting targeted therapies in the development of precision medicine. This review article emphasizes studies on environmental factors affecting AD development and novel biological agents used in the treatment of AD. Best evidence of the clinical efficacy of novel immunologic approaches using biological agents in patients with AD is available for the anti-IL-4 receptor α-chain antibody dupilumab, but a number of studies are currently ongoing with other specific antagonists to immune system players. These targeted molecules can be expressed on or drive the cellular players infiltrating the skin (eg, T lymphocytes, dendritic cells, or eosinophils). Such approaches can have immunomodulatory and thereby beneficial clinical effects on the overall skin condition, as well as on the underlying immune deviation that might play a role in comorbidities. An effect of these immunologic treatments on pruritus and the disturbed microbiome in patients with AD has other potential consequences for treatment.

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

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

All the "RAGE" in lung disease: The receptor for advanced glycation endproducts (RAGE) is a major mediator of pulmonary inflammatory responses

The receptor for advanced glycation endproducts (RAGE) is a pro-inflammatory pattern recognition receptor (PRR) that has been implicated in the pathogenesis of numerous inflammatory diseases. It was discovered in 1992 on endothelial cells and was named for its ability to bind advanced glycation endproducts and promote vascular inflammation in the vessels of patients with diabetes. Further studies revealed that RAGE is most highly expressed in lung tissue and spurred numerous explorations into RAGE's role in the lung. These studies have found that RAGE is an important mediator in allergic airway inflammation (AAI) and asthma, pulmonary fibrosis, lung cancer, chronic obstructive pulmonary disease (COPD), acute lung injury, pneumonia, cystic fibrosis, and bronchopulmonary dysplasia. RAGE has not yet been targeted in the lungs of paediatric or adult clinical populations, but the development of new ways to inhibit RAGE is setting the stage for the emergence of novel therapeutic agents for patients suffering from these pulmonary conditions.

Diagnostic and Predictive Levels of Calcium-binding Protein A8 and Tumor Necrosis Factor Receptor-associated Factor 6 in Sepsis-associated Encephalopathy: A Prospective Observational Study

Background:

Despite its high prevalence, morbidity, and mortality, sepsis-associated encephalopathy (SAE) is still poorly understood. The aim of this prospective and observational study was to investigate the clinical significance of calcium-binding protein A8 (S100A8) in serum and tumor necrosis factor receptor-associated factor 6 (TRAF6) in peripheral blood mononuclear cells (PBMCs) in diagnosing SAE and predicting its prognosis.

Methods:

Data of septic patients were collected within 24 h after Intensive Care Unit admission from July 2014 to March 2015. Healthy medical personnel served as the control group. SAE was defined as cerebral dysfunction in the presence of sepsis that fulfilled the exclusion criteria. The biochemical indicators, Glasgow Coma Scale, Acute Physiology and Chronic Health Evaluation score II, TRAF6 in PBMC, serum S100A8, S100β, and neuron-specific enolase were evaluated in SAE patients afresh. TRAF6 and S100A8 were also measured in the control group.

Results:

Of the 57 enrolled patients, 29 were diagnosed with SAE. The S100A8 and TRAF6 concentrations in SAE patients were both significantly higher than that in no-encephalopathy (NE) patients, and higher in NE than that in controls (3.74 ± 3.13 vs. 1.08 ± 0.75 vs. 0.37 ± 0.14 ng/ml, P < 0.01; 3.18 ± 1.55 vs. 1.02 ± 0.63 vs. 0.47 ± 0.10, P < 0.01). S100A8 levels of 1.93 ng/ml were diagnostic of SAE with 92.90% specificity and 69.00% sensitivity in the receiver operating characteristic (ROC) curve, and the area under the curve was 0.86 (95% confidence interval [CI]: 0.76–0.95). TRAF6-relative levels of 1.44 were diagnostic of SAE with 85.70% specificity and 86.20% sensitivity, and the area under the curve was 0.94 (95% CI: 0.88–0.99). In addition, S100A8 levels of 2.41 ng/ml predicted 28-day mortality of SAE with 90.00% specificity and 73.70% sensitivity in the ROC curve, and the area under the curve was 0.88. TRAF6 relative levels of 2.94 predicted 28-day mortality of SAE with 80.00% specificity and 68.40% sensitivity, and the area under the curve was 0.77. Compared with TRAF6, the specificity of serum S100A8 in diagnosing SAE and predicting mortality was higher, although the sensitivity was low. In contrast, the TRAF6 had higher sensitivity for diagnosis.

Conclusions:

Peripheral blood levels of S100A8 and TRAF6 in SAE patients were elevated and might be related to the severity of SAE and predict the outcome of SAE. The efficacy and specificity of S100A8 for SAE diagnosis were superior, despite its weak sensitivity. S100A8 might be a better biomarker for diagnosis of SAE and predicting prognosis.

Molecular Mechanisms of Cutaneous Inflammatory Disorder: Atopic Dermatitis

Atopic dermatitis (AD) is a multifactorial inflammatory skin disease resulting from interactions between genetic susceptibility and environmental factors. The pathogenesis of AD is poorly understood, and the treatment of recalcitrant AD is still challenging. There is accumulating evidence for new gene polymorphisms related to the epidermal barrier function and innate and adaptive immunity in patients with AD. Newly-found T cells and dendritic cell subsets, cytokines, chemokines and signaling pathways have extended our understanding of the molecular pathomechanism underlying AD. Genetic changes caused by environmental factors have been shown to contribute to the pathogenesis of AD. We herein present a review of the genetics, epigenetics, barrier dysfunction and immunological abnormalities in AD with a focus on updated molecular biology.

Cytokine secreted by S100A9 via TLR4 in monocytes delays neutrophil apoptosis by inhibition of caspase 9/3 pathway

Dysregulation of neutrophil apoptosis causes pathogenesis and aggravation of allergy. S100A9 exists as one of the proteins in the neutrophils, triggering inflammatory responses by activating the immune cells. In this study, we investigated whether S100A9 affects constitutive neutrophil apoptosis by activating the monocytes in normal and allergic subjects. Supernatant from human monocytic THP-1 cells after treatment with S100A9 suppressed normal neutrophil apoptosis by inhibiting the activations of caspase 9 and caspase 3. S100A9 upregulated the release of MCP-1, IL-6, and IL-8 in THP-1 cells. An increase in cytokine was suppressed by CLI-095, a Toll-like receptor (TLR) 4 inhibitor, PP2, a Src inhibitor, rottlerin, a PKCδ inhibitor, MAP kinase inhibitors, including PD98059, SB202190, and SP600125, and BAY-11-7085, an NF-κB inhibitor. Src, PKCδ, ERK1/2, p38 MAPK, and JNK were phosphorylated by S100A9. The phosphorylation of Src and PKCδ was suppressed by CLI-095, and the activation of ERK1/2, p38 MAPK, and JNK was inhibited by CLI-095, PP2, and rottlerin. S100A9 induced NF-κB activity, and the activation was suppressed by CLI-095, PP2, rottlerin, and MAPK kinase inhibitors. In normal and allergic subjects, supernatant from normal and allergic monocytes after stimulation with S100A9 suppressed normal and allergic neutrophil apoptosis, respectively; MCP-1, IL-6, and IL-8 in the supernatant was increased by S100A9. The cytokine secretion induced by S100A9 is related to TLR4, Src, PKCδ, ERK1/2, p38 MAPK, JNK, and NF-κB. Taken together, S100A9 induces anti-apoptotic effect on normal and allergic neutrophils by increasing cytokine secretion of monocytes. These findings may help us to better understand neutrophil apoptosis regulated by S100A9 and pathogenesis of allergic diseases.

Differential expression of inflammation-related genes in IL-4 transgenic mice before and after the onset of atopic dermatitis skin lesions

IL-4 plays an important role in the pathogenesis of atopic dermatitis (AD), a common chronic inflammatory skin disease. We have generated IL-4 transgenic (Tg) mice by over-expressing IL-4 in the epidermis. These mice spontaneously develop chronic pruritic inflammatory skin lesions, which meet the clinical and histological diagnostic criteria for human AD. Systemic survey of immune-related genes in this mouse model, however, has not been performed. In this study, we utilize PCR array technique to examine hundreds of inflammation-related genes in the IL-4 Tg mice before and after the onset of skin lesions as well as in their wild type (WT) littermates. Only those genes with at least 2-fold up-regulation or down-regulation and with a P-value of less than 0.05 in comparison to WT controls were identified and analyzed. In the skin lesions, many chemokines, pro-inflammatory cytokines, and other AD-related factors are dysregulated compared to the wild type mice. Particularly, CXCL5, IL-1β, IL-24, IL-6, oncostatin M, PTGS2, FPR1 and REG3γ are up-regulated several hundred-fold. In the pre-lesional group that shows no obvious skin abnormality on clinical observation, 30 dysregulated genes are nevertheless identified though the fold changes are much less than that of the lesional group, including CCL6, CCL8, CCL11, CCL17, CXCL13, CXCL14, CXCR3 and IL-12Rβ2. Finally using ELISA, we demonstrate that 4 most dramatically up-regulated factors in the skin are also elevated in the peripheral blood of the IL-4 Tg mice. Taken together, our data have identified hundreds of dysregulated factors in the IL-4 Tg mice before and after the onset of skin lesions. Future detailed examination of these factors will shed light on our understanding of the development and progression of AD and help to discover important biomarkers for clinical AD diagnosis and treatment.

Meta-analysis derived atopic dermatitis (MADAD) transcriptome defines a robust AD signature highlighting the involvement of atherosclerosis and lipid metabolism pathways

Background

Atopic dermatitis (AD) is a common inflammatory skin disease with limited treatment options. Several microarray experiments have been conducted on lesional/LS and non-lesional/NL AD skin to develop a genomic disease phenotype. Although these experiments have shed light on disease pathology, inter-study comparisons reveal large differences in resulting sets of differentially expressed genes (DEGs), limiting the utility of direct comparisons across studies.

Methods

We carried out a meta-analysis combining 4 published AD datasets to define a robust disease profile, termed meta-analysis derived AD (MADAD) transcriptome.

Results

This transcriptome enriches key AD pathways more than the individual studies, and associates AD with novel pathways, such as atherosclerosis signaling (IL-37, selectin E/SELE). We identified wide lipid abnormalities and, for the first time in vivo, correlated Th2 immune activation with downregulation of key epidermal lipids (FA2H, FAR2, ELOVL3), emphasizing the role of cytokines on the barrier disruption in AD. Key AD “classifier genes” discriminate lesional from nonlesional skin, and may evaluate therapeutic responses.

Conclusions

Our meta-analysis provides novel and powerful insights into AD disease pathology, and reinforces the concept of AD as a systemic disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0133-x) contains supplementary material, which is available to authorized users.

Comparative Genomic, MicroRNA, and Tissue Analyses Reveal Subtle Differences between Non-Diabetic and Diabetic Foot Skin

Diabetes Mellitus (DM) is a chronic, severe disease rapidly increasing in incidence and prevalence and is associated with numerous complications. Patients with DM are at high risk of developing diabetic foot ulcers (DFU) that often lead to lower limb amputations, long term disability, and a shortened lifespan. Despite this, the effects of DM on human foot skin biology are largely unknown. Thus, the focus of this study was to determine whether DM changes foot skin biology predisposing it for healing impairment and development of DFU. Foot skin samples were collected from 20 patients receiving corrective foot surgery and, using a combination of multiple molecular and cellular approaches, we performed comparative analyses of non-ulcerated non-neuropathic diabetic foot skin (DFS) and healthy non-diabetic foot skin (NFS). MicroRNA (miR) profiling of laser captured epidermis and primary dermal fibroblasts from both DFS and NFS samples identified 5 miRs de-regulated in the epidermis of DFS though none reached statistical significance. MiR-31-5p and miR-31-3p were most profoundly induced. Although none were significantly regulated in diabetic fibroblasts, miR-29c-3p showed a trend of up-regulation, which was confirmed by qPCR in a prospective set of 20 skin samples. Gene expression profiling of full thickness biopsies identified 36 de-regulated genes in DFS (>2 fold-change, unadjusted p-value ≤ 0.05). Of this group, three out of seven tested genes were confirmed by qPCR: SERPINB3 was up-regulated whereas OR2A4 and LGR5 were down-regulated in DFS. However no morphological differences in histology, collagen deposition, and number of blood vessels or lymphocytes were found. No difference in proliferative capacity was observed by quantification of Ki67 positive cells in epidermis. These findings suggest DM causes only subtle changes to foot skin. Since morphology, mRNA and miR levels were not affected in a major way, additional factors, such as neuropathy, vascular complications, or duration of DM, may further compromise tissue's healing ability leading to development of DFUs.

The Effects of Antigen-Specific IgG1 Antibody for the Pulmonary-Hypertension-Phenotype and B Cells for Inflammation in Mice Exposed to Antigen and Fine Particles from Air Pollution

Air pollution is known to exacerbate chronic inflammatory conditions of the lungs including pulmonary hypertension, cardiovascular diseases and autoimmune diseases. Directly pathogenic antibodies bind pro-inflammatory cell receptors and cause or exacerbate inflammation. In contrast, anti-inflammatory antibody isotypes (e.g. mouse immunoglobulin G1, IgG1) bind inhibitory cell receptors and can inhibit inflammation. Our previous studies showed that co-exposure to antigen and urban ambient particulate matter (PM_2.5) induced severe pulmonary arterial thickening and increased right ventricular systolic pressures in mice via T-cell produced cytokines, Interleukin (IL)-13 and IL-17A. The aim of the current study was to understand how B cell and antibody responses integrate into this T cell cytokine network for the pulmonary hypertension phenotype. Special focus was on antigen-specific IgG1 that is the predominant antibody in the experimental response to antigen and urban ambient PM_2.5. Wild type and B cell-deficient mice were primed with antigen and then challenged with antigen and urban particulate matter and injected with antibodies as appropriate. Our data surprisingly showed that B cells were necessary for the development of increased right ventricular pressures and molecular changes in the right heart in response to sensitization and intranasal challenge with antigen and PM_2.5. Further, our studies showed that both, the increase in right ventricular systolic pressure and right ventricular molecular changes were restored by reconstituting the B cell KO mice with antigen specific IgG1. In addition, our studies identified a critical, non-redundant role of B cells for the IL-17A-directed inflammation in response to exposure with antigen and PM_2.5, which was not corrected with antigen-specific IgG1. In contrast, IL-13-directed inflammatory markers, as well as severe pulmonary arterial remodeling induced by challenge with antigen and PM_2.5 were similar in B cell-deficient and wild type mice. Our studies have identified B cells and antigen specific IgG1 as potential therapeutic targets for pulmonary hypertension associated with immune dysfunction and environmental exposures.