Mechanisms of IFN-γ-induced apoptosis of human skin keratinocytes in patients with atopic dermatitis

Causal relationships between dietary antioxidant vitamin intake and atopic dermatitis: A two-sample Mendelian randomization study

OBJECTIVE

Oxidative stress is strongly associated with atopic dermatitis (AD), and increased antioxidant intake could potentially reduce the risk of or alleviate its symptoms. However, the argument is disputed. Therefore, we conducted a Mendelian randomization (MR) analysis to explore the causal relationship between dietary antioxidant vitamin intake and AD.

METHODS

We applied MR analysis to examine the causative association between dietary antioxidant vitamin intake (vitamin C, vitamin E, carotene, and retinol) and AD. The genome-wide association study (GWAS) summary data for antioxidant vitamins intake and AD were obtained from the IEU OpenGWAS database and the UK biobank. Our study consisted of two major parts, MR analysis to detect the causal relationship between exposure and outcome, and sensitivity analysis as supplemental evidence to verify the robustness of the results.

RESULT

The results revealed a suggestive causal relationship between vitamin E intake and AD (p = 0.038, OR 95% CI = 0.745-0.992). However, there was no causal relationship between the other three vitamins (vitamin C, carotene, and retinol) and AD (p = 0.507, OR 95% CI = 0.826-1.099) (p = 0.890, OR 95% CI = 0.864-1.184) (p = 0.492, OR 95% CI = 0.893-1.264). None of the single nucleotide polymorphisms (SNPs) were detected as heterogeneous and pleiotropy in the sensitivity analysis (p > 0.05).

CONCLUSION

The analysis suggested that dietary intake of vitamin E may potentially lower the risk of AD. Conversely, intake of vitamin C, retinol, and carotene is not causally related to AD. Although vitamin E intake could be protective against AD, intake of dietary antioxidant vitamins to prevent or treat AD is not necessary.

Tissue gene expression profiles and communication networks inform candidate blood biomarker identification in psoriasis and atopic dermatitis

Overlapping clinical and pathomechanistic features can complicate the diagnosis and treatment of inflammatory skin diseases, including psoriasis and atopic dermatitis (AD). Spatial transcriptomics allows the identification of disease- and cell-specific molecular signatures that may advance biomarker development and future treatments. This study identified transcriptional signatures in keratinocytes and sub-basal CD4+ and CD8+ T lymphocytes from patients with psoriasis and AD. In silico prediction of ligand:receptor interactions delivered key signalling pathways (interferon, effector T cells, stroma cell and matrix biology, neuronal development, etc.). Targeted validation of selected transcripts, including CCL22, RELB, and JUND, in peripheral blood T cells suggests the chosen approach as a promising tool also in other inflammatory diseases. Psoriasis and AD are characterized by transcriptional dysregulation in T cells and keratinocytes that may be targeted therapeutically. Spatial transcriptomics is a valuable tool in the search for molecular signatures that can be used as biomarkers and/or therapeutic targets.

Foxp3+ Treg control allergic skin inflammation by restricting IFN-γ-driven neutrophilic infiltration and NETosis

BACKGROUND

Atopic dermatitis (AD), a chronic inflammatory skin disease with T cell activation as a key feature, in which Th2 cell-mediated responses play a pivotal role. Regulatory T cells (Treg) are central immune cells that restrict autoimmunity and inflammation in the body. Patients with immune dysregulation, polyendocrinopathy, or enteropathy X-linked syndrome, an immune disease characterized by a deficiency in Treg, develop skin inflammation and allergic disorders, indicating that Treg play a crucial role in the development of allergic skin inflammation.

OBJECTIVE

we investigated the underlying mechanisms by which Treg control cutaneous allergic inflammation.

METHODS

An allergic skin inflammation mouse model was constructed using MC903, and Treg-depleted mouse model was constructed using diphtheria toxin. Neutralization of IFN-γ was constructed using anti-mouse-IFN-γ mouse antibody. Neutrophil infiltration was analyzed by flow cytometry and immunohistochemistry. Neutrophil extracellular traps (NETs), a process called NETosis, were detected using immunofluorescence. In vitro neutrophil stimulation and immunocytochemistry was conducted to demonstrate the effect of IFN-γ on NETosis.

RESULTS

The depletion of Foxp3+ Treg led to significantly exacerbated AD-like skin inflammation, including increased recruitment of neutrophils and expression of Th1 cytokine IFN-γ. Neutrophil infiltrating in skin of Treg-depleted mice released more NETs than wild type. Neutralization of IFN-γ abolished neutrophil infiltration and NETosis in Treg-depleted mice. Neutrophils stimulated with IFN-γ were more prone to release NETs in vitro. Finally, Foxp3+ Treg control cutaneous allergic inflammation by regulating IFN-γ-driven neutrophilic infiltration and NETosis.

CONCLUSION

Our results highlight the previously underestimated Treg-IFN-γ-neutrophil inflammatory axis.

Impact of fucosyltransferase 1-mediated epidermal blood group antigen H on anti-inflammatory response in atopic dermatitis

The presence of the blood group H2 antigen on the membrane of red blood cells determines blood type O in individuals and this H2 antigen serves as a precursor to the A and B antigens expressed in blood types A and B, respectively. However, the specific involvement of ABH antigens in skin diseases is unknown. Therefore, we aim to investigate the expression of ABH antigens in skin tissue of patients with atopic dermatitis (AD) and MC903-induced AD-like mice. We demonstrated that the expression of ABH antigen is primarily located in the granular and horny layers of the skin in healthy control individuals. However, in patients with AD, the expression of the ABH antigen was absent or diminished in these layers, while the H2 antigen expression increased in the spinous layers of the affected skin lesions. Then, we investigated the biological function of blood group H antigen mediated by fucosyltransferase 1 (Fut1) in the skin, utilizing an AD mouse model induced by MC903 in wild-type (WT) and Fut1-knockout mice. After the application of MC903, Fut1-deficient mice, with no H2 antigen expression on their skin, exhibited more severe clinical signs, increased ear swelling, and elevated serum IgE levels compared with those of WT mice. Additionally, the MC903-induced thickening of both the epidermis and dermis was more pronounced in Fut1-deficient mice than that in WT mice. Furthermore, Fut1-deficient mice showed a significantly higher production of interleukin-4 (IL-4) and IL-6 in skin lesions compared with that of their WT counterparts. The expression of chemokines, particularly Ccl2 and Ccl8, was notably higher in Fut1-deficient mice compared with those of WT mice. The infiltration of CD4+ T cells, eosinophils, and mast cells into the lesional skin was significantly elevated in Fut1-deficient mice compared with that in WT mice. These findings demonstrate the protective role of H2 antigen expression against AD-like inflammation and highlight its potential therapeutic impact on AD through the regulation of blood group antigens.

Dupilumab-associated head and neck dermatitis shows a pronounced type 22 immune signature mediated by oligoclonally expanded T cells

Dupilumab, an IL4R-blocking antibody, has shown clinical efficacy for atopic dermatitis (AD) treatment. In addition to conjunctivitis/blepharitis, the de novo appearance of head/neck dermatitis is now recognized as a distinct side effect, occurring in up to 10% of patients. Histopathological features distinct from AD suggest a drug effect, but exact underlying mechanisms remain unknown. We profiled punch biopsies from dupilumab-associated head and neck dermatitis (DAHND) by using single-cell RNA sequencing and compared data with untreated AD and healthy control skin. We show that dupilumab treatment was accompanied by normalization of IL-4/IL-13 downstream activity markers such as CCL13, CCL17, CCL18 and CCL26. By contrast, we found strong increases in type 22-associated markers (IL22, AHR) especially in oligoclonally expanded T cells, accompanied by enhanced keratinocyte activation and IL-22 receptor upregulation. Taken together, we demonstrate that dupilumab effectively dampens conventional type 2 inflammation in DAHND lesions, with concomitant hyperactivation of IL22-associated responses.

The epidermal lipid-microbiome loop and immunity: Important players in atopic dermatitis

BACKGROUND

The promotion of epidermal barrier dysfunction is attributed to abnormalities in the lipid-microbiome positive feedback loop which significantly influences the imbalance of the epithelial immune microenvironment (EIME) in atopic dermatitis (AD). This imbalance encompasses impaired lamellar membrane integrity, heightened exposure to epidermal pathogens, and the regulation of innate and adaptive immunity. The lipid-microbiome loop is substantially influenced by intense adaptive immunity which is triggered by abnormal loop activity and affects the loop's integrity through the induction of atypical lipid composition and responses to dysregulated epidermal microbes. Immune responses participate in lipid abnormalities within the EIME by downregulating barrier gene expression and are further cascade-amplified by microbial dysregulation which is instigated by barrier impairment.

AIM OF REVIEW

This review examines the relationship between abnormal lipid composition, microbiome disturbances, and immune responses in AD while progressively substantiating the crosstalk mechanism among these factors. Based on this analysis, the "lipid-microbiome" positive feedback loop, regulated by immune responses, is proposed.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The review delves into the impact of adaptive immune responses that regulate the EIME, driving AD, and investigates potential mechanisms by which lipid supplementation and probiotics may alleviate AD through the up-regulation of the epidermal barrier and modulation of immune signaling. This exploration offers support for targeting the EIME to attenuate AD.

Interferon-γ signaling in eosinophilic esophagitis has implications for epithelial barrier function and programmed cell death

Objective

Eosinophilic esophagitis (EoE) is a chronic esophageal inflammatory disorder characterized by eosinophil-rich mucosal inflammation and tissue remodeling. Transcriptional profiling of esophageal biopsies has previously revealed upregulation of type I and II interferon (IFN) response genes. We aim to unravel interactions between immune and epithelial cells and examine functional significance in esophageal epithelial cells.

Design

We investigated epithelial gene expression from EoE patients using single-cell RNA sequencing and a confirmatory bulk RNA-sequencing experiment of isolated epithelial cells. The functional impact of interferon signaling on epithelial cells was investigated using in vitro organoid models.

Results

We observe upregulation of interferon response signature genes (ISGs) in the esophageal epithelium during active EoE compared to other cell types, single-cell data, and pathway analyses, identified upregulation in ISGs in epithelial cells isolated from EoE patients. Using an esophageal organoid and air-liquid interface models, we demonstrate that IFN-γ stimulation triggered disruption of esophageal epithelial differentiation, barrier integrity, and induced apoptosis via caspase upregulation. We show that an increase in cleaved caspase-3 is seen in EoE tissue and identify interferon gamma (IFNG) expression predominantly in a cluster of majority-CD8+ T cells with high expression of CD69 and FOS.

Conclusion

These findings offer insight into the interplay between immune and epithelial cells in EoE. Our data illustrate the relevance of several IFN-γ-mediated mechanisms on epithelial function in the esophagus, which have the potential to impact epithelial function during inflammatory conditions.

KRT6A Inhibits IL-1β-Mediated Pyroptosis of Keratinocytes via Blocking IL-17 Signaling

Keratin 6A (KRT6A) is involved in the pathogenesis of various skin diseases. However, the reports on the roles of KRT6A in atopic dermatitis (AD) are limited. This study aimed to investigate the potentials of KRT6A in AD. mRNA levels were detected by RT-PCR. Cytokine release was determined by ELISA. Protein expression was determined using Western blot. Cell viability was determined by CCK-8. Cytotoxicity was detected by LDH assay. Cell death was determined by TUNEL. The pyroptosis of keratinocytes was detected using flow cytometry. We found that KRT6A was overexpressed in AD patients. Moreover, KRT6A was stimulated after exposed to proinflammatory cytokines. Overexpressed KRT6A suppressed inflammatory response, while KRT6A knockdown exerted the opposite effects. Overexpressed KRT6A suppressed inflammation-induced pyroptosis of keratinocytes. Additionally, KRT6A negatively regulated interleukin-17a (IL-17a) expression, blocking IL-17 signaling. IL-17a overexpression antagonized the effects of KRT6A and promoted pyroptosis of keratinocytes. In conclusion, KRT6A exerted protective functions in AD via regulating IL-17 signaling. This KRT6A/IL-17 may be a novel target for AD.

Special Considerations of Atopic Dermatitis in Skin of Color

Atopic dermatitis (AD) is a chronic inflammatory skin condition with heterogeneous presentations and prevalence across different skin tones. In this chapter, AD is explored through the lens of racial and ethnic diversity, emphasizing the special considerations among patients with skin of color (SOC). Specific ethnic groups may exhibit unique AD phenotypes, and these differences pose unique diagnostic and management challenges, especially given the disproportionate impact of AD in African American and Asian populations due to environmental exposures and social factors (i.e., decreased access to healthcare resources). Addressing these social disparities, increasing representation in medical education and the clinical space, as well as ongoing research can help better serve this patient population.

Transcriptional differences between vesicular hand eczema and atopic dermatitis

BACKGROUND

Transcriptome analyses of vesicular hand eczema (VHE) indicated a large overlap with atopic dermatitis (AD). However, differentially expressed genes (DEGs) that differentiate VHE from AD are unknown.

OBJECTIVE

To identify distinctive transcriptional features of VHE in comparison to AD.

METHODS

We re-analysed RNA sequencing data of 10 lesional palmar VHE epidermal biopsies and performed DEG analyses. We adjusted the obtained DEG results of 57 lesional whole AD skin biopsies of the upper extremities or trunk to our criteria. Up- and down-regulated DEGs in both skin diseases, VHE-only, AD-only, and opposite regulated DEGs were identified. Enrichment analyses and Chi-squared tests were conducted to test for differences in gene set enrichment between both skin diseases.

RESULTS

Comparing 3028 DEGs in VHE (1645 up; 1383 down) with 5391 DEGs in AD (3842 up; 1549 down), revealed 1516 shared DEGs (1179 up; 337 down) and 1512 DEGs unique to VHE (466 up, 1046 down). Interferon signalling and necroptosis were significantly more prominent in VHE compared to AD. Downregulated genes identified only in VHE (like DNASE1L2, KRT2, KRT9 and KRT25) indicate an aberrant epidermal differentiation.

CONCLUSION

Our study indicates a common pathophysiology between VHE and AD, but also reveals transcriptional differences between VHE and AD.

Regulatory T cells control Staphylococcus aureus and disease severity of cutaneous leishmaniasis

Cutaneous leishmaniasis causes alterations in the skin microbiota, leading to pathologic immune responses and delayed healing. However, it is not known how these microbiota-driven immune responses are regulated. Here, we report that depletion of Foxp3+ regulatory T cells (Tregs) in Staphylococcus aureus-colonized mice resulted in less IL-17 and an IFN-γ-dependent skin inflammation with impaired S. aureus immunity. Similarly, reducing Tregs in S. aureus-colonized and Leishmania braziliensis-infected mice increased IFN-γ, S. aureus, and disease severity. Importantly, analysis of lesions from L. braziliensis patients revealed that low FOXP3 gene expression is associated with high IFNG expression, S. aureus burden, and delayed lesion resolution compared to patients with high FOXP3 expression. Thus, we found a critical role for Tregs in regulating the balance between IL-17 and IFN-γ in the skin, which influences both bacterial burden and disease. These results have clinical ramifications for cutaneous leishmaniasis and other skin diseases associated with a dysregulated microbiome when Tregs are limited or dysfunctional.

Nomenclature of allergic diseases and hypersensitivity reactions: Adapted to modern needs: An EAACI position paper

The exponential growth of precision diagnostic tools, including omic technologies, molecular diagnostics, sophisticated genetic and epigenetic editing, imaging and nano-technologies and patient access to extensive health care, has resulted in vast amounts of unbiased data enabling in-depth disease characterization. New disease endotypes have been identified for various allergic diseases and triggered the gradual transition from a disease description focused on symptoms to identifying biomarkers and intricate pathogenetic and metabolic pathways. Consequently, the current disease taxonomy has to be revised for better categorization. This European Academy of Allergy and Clinical Immunology Position Paper responds to this challenge and provides a modern nomenclature for allergic diseases, which respects the earlier classifications back to the early 20th century. Hypersensitivity reactions originally described by Gell and Coombs have been extended into nine different types comprising antibody- (I-III), cell-mediated (IVa-c), tissue-driven mechanisms (V-VI) and direct response to chemicals (VII). Types I-III are linked to classical and newly described clinical conditions. Type IVa-c are specified and detailed according to the current understanding of T1, T2 and T3 responses. Types V-VI involve epithelial barrier defects and metabolic-induced immune dysregulation, while direct cellular and inflammatory responses to chemicals are covered in type VII. It is notable that several combinations of mixed types may appear in the clinical setting. The clinical relevance of the current approach for allergy practice will be conferred in another article that will follow this year, aiming at showing the relevance in clinical practice where various endotypes can overlap and evolve over the lifetime.

Critical role of epigenetic modification in the pathogenesis of atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease characterised by recurrent eczema-like lesions and severe pruritus, along with drying and decrustation of skin. Current research relates the pathogenesis of atopic dermatitis mainly to genetic susceptibility, abnormal skin barrier function, immune disorders, Staphylococcus aureus colonisation, microbiological dysfunction and vitamin D insufficiency. Epigenetic modifications are distinct genetic phenotypes resulting from environment-driven changes in chromosome functions in the absence of nuclear DNA sequence variation. Classic epigenetic events include DNA methylation, histone protein modifications and non-coding RNA regulation. Increasing evidence has indicated that epigenetic events are involved in the pathogenesis of atopic dermatitis by their effects on multiple signalling pathways which in turn influence the above factors. This review primarily analyses the function of epigenetic regulation in the pathogenesis of atopic dermatitis. In addition, it tries to make recommendations for personalised epigenetic treatment strategies for atopic dermatitis in the future.

Modelling of indirect cell-cell interaction networks mediated by IFNγ/IL-4 cytokine involved in atopic dermatitis

Atopic dermatitis (AD) is an immune-driven inflammatory skin disease that is known to have a significantly high life-time prevalence in the human population. T-helper (Th) immune cells play a key role in the pathogenesis of AD which is marked by defects in the skin barrier function along with a significant increase in the population of either Th1 or Th2 sub-types of Th cells. The progression of AD from the acute to chronic phase is still poorly understood, and here we explore the mechanism of this transition through the study of a mathematical model for indirect cell-cell interactions among Th and skin cells via the secreted cytokines IFNγ and IL-4, both known to have therapeutic potential. An increase in the level of cytokine IFN γ can catalyse the transition of AD from an acute to a chronic stage, while an increase in the level of cytokine IL-4 has the reverse effect. In our model, the transition of AD from the acute to chronic stage and vice versa can be abrupt (switch-like) with hysteresis: this bistable behaviour can potentially be used to keep AD in the acute phase since therapy based on suppression of IFNγ can retard the transition to the chronic phase.

Molecular networks in atopic mothers impact the risk of infant atopy

BACKGROUND

The prevalence of atopic diseases has increased with atopic dermatitis (AD) as the earliest manifestation. We assessed if molecular risk factors in atopic mothers influence their infants' susceptibility to an atopic disease.

METHODS

Pregnant women and their infants with (n = 174, high-risk) or without (n = 126, low-risk) parental atopy were enrolled in a prospective birth cohort. Global differentially methylated regions (DMRs) were determined in atopic (n = 92) and non-atopic (n = 82) mothers. Principal component analysis was used to predict atopy risk in children dependent on maternal atopy. Genome-wide transcriptomic analyses were performed in paired atopic (n = 20) and non-atopic (n = 15) mothers and cord blood. Integrative genomic analyses were conducted to define methylation-gene expression relationships.

RESULTS

Atopic dermatitis was more prevalent in high-risk compared to low-risk children by age 2. Differential methylation analyses identified 165 DMRs distinguishing atopic from non-atopic mothers. Inclusion of DMRs in addition to maternal atopy significantly increased the odds ratio to develop AD in children from 2.56 to 4.26. In atopic compared to non-atopic mothers, 139 differentially expressed genes (DEGs) were identified significantly enriched of genes within the interferon signaling pathway. Expression quantitative trait methylation analyses dependent on maternal atopy identified 29 DEGs controlled by 136 trans-acting methylation marks, some located near transcription factors. Differential expression for the same nine genes, including MX1 and IFI6 within the interferon pathway, was identified in atopic and non-atopic mothers and high-risk and low-risk children.

CONCLUSION

These data suggest that in utero epigenetic and transcriptomic mechanisms predominantly involving the interferon pathway may impact and predict the development of infant atopy.

Application of network composite module analysis and verification to explore the bidirectional immunomodulatory effect of Zukamu granules on Th1 / Th2 cytokines in lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

Zukamu granules (ZKMG), as the preferred drug for the treatment of colds in Uygur medical theory, has been used for 1500 years. It is also widely used in China and included in the National Essential Drugs List (2018 edition). It has unique anti-inflammatory, antitussive and analgesic effects.

AIM OF THE STUDY

Aiming at the research of traditional Chinese medicine (TCM) with the characteristics of overall regulation of body diseases and the immune regulation mechanism with the concept of integrity, this paper put forward the integrated application of network composite module analysis and animal experiment verification to study the immune regulation mechanism of TCM.

MATERIALS AND METHODS

The active components and targets of ZKMG were predicted, and network module analysis was performed to explore their potential immunomodulatory mechanisms. Then acute lung injury (ALI) mice and idiopathic pulmonary fibrosis (IPF) rats were used as pathological models to observe the effects of ZKMG on the pathological conditions of infected ALI and IPF rats, determine the contents of Th1, Th2 characteristic cytokines and immunoglobulins, and study the intervention of GATA3/STAT6 signal pathway.

RESULTS

The results of network composite module analysis showed that ZKMG contained 173 pharmacodynamic components and 249 potential targets, and four key modules were obtained. The immunomodulatory effects of ZKMG were related to T cell receptor signaling pathway. The validation results of bioeffects that ZKMG could carry out bidirectional immune regulation on Th1/Th2 cytokines in the stage of ALI and IPF, so as to play the role of regulating immune homeostasis and organ protection.

CONCLUSIONS

The network composite module analysis and verification method is an exploration to study the immune regulation mechanism of TCM by combining the network module prediction analysis with animal experiments, which provides a reference for subsequent research.

Genome-Wide Integration of Genetic and Genomic Studies of Atopic Dermatitis: Insights into Genetic Architecture and Pathogenesis

Atopic dermatitis (AD) is a common heterogeneous, chronic, itching, and inflammatory skin disease. Genetic studies have identified multiple AD susceptibility genes. However, the genetic architecture of AD has not been elucidated. In this study, we conducted a large-scale meta-analysis of AD (35,647 cases and 1,013,885 controls) to characterize the genetic basis of AD. The heritability of AD in different datasets varied from 0.6 to 7.1%. We identified 31 previously unreported genes by integrating multiomics data. Among the 31 genes, MCL1 was identified as a potential treatment target for AD by mediating gene‒drug interactions. Tissue enrichment analyses and phenome-wide association study provided strong support for the role of the hemic and immune systems in AD. Across 1,207 complex traits and diseases, genetic correlations indicated that AD shared links with multiple respiratory phenotypes. The phenome-wide Mendelian randomization analysis (Mendelian randomization‒phenome-wide association study) revealed that the age of onset of diabetes exhibited a positive causal effect on AD (inverse-variance weighted β = 0.39, SEM = 0.09, P = 2.77 × 10^-5). Overall, these results provide important insights into the genetic architecture of AD and will lead to a more thorough and complete understanding of the molecular mechanisms underlying AD.

Single-Cell RNA Sequencing Reveals the Immune Cell Profiling in IMQ Induced Psoriasis-Like Model

PURPOSE

Psoriasis is a chronic systemic inflammatory skin disease with a high recurrence rate. The immune response plays an important role in psoriasis. However, the subsets of immune cells involved in inflammation in psoriatic mice have not been fully studied. This study showed the immune environment characteristics of psoriasis in mice.

METHODS

We used single-cell RNA sequencing (10× Genomics) as an unbiased analytical strategy to investigate the heterogeneity of skin immune cells in imiquimod-induced psoriasis mice systematically.

RESULTS

We identified 10 major clusters and their marker genes among 14,439 cells. The proportions of macrophages, NK/T cells, conventional dendritic cells (cDCs) and plasmacytoid dendritic cells (pDCs) were increased in psoriatic mice. Macrophages were the largest group and were further divided into 7 subgroups, and all macrophage clusters were increased in psoriatic mice. Differentially expressed genes in control versus psoriatic mice skin lesions showed that Fcgr4, Saa3 and Acp5 in macrophages, Acp5, Fcgr4 and Ms4a6d in NK/T cells, Saa3 in cDCs, and Ifitm1 in pDCs were upregulated in psoriasis mice. Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis emphasized the role of oxidative phosphorylation signals and antigen processing and presentation signals in murine psoriasis-like models.

CONCLUSION

Our study reveals the immune environment characteristics of the commonly used IMQ induced psoriasis-like models and provides a systematic insight into the immune response of mice with psoriasis, which is conducive to comparing the similarities and differences between the mouse model and human psoriasis.

Mitochondrial Activity Is Upregulated in Nonlesional Atopic Dermatitis and Amenable to Therapeutic Intervention

Previous work has shown increased expression of genes related to oxidative stress in nonlesional atopic dermatitis (ADNL) skin. Although mitochondria are key regulators of ROS production, their function in AD has never been investigated. Energy metabolism and the oxidative stress response were studied in keratinocytes (KCs) from patients with ADNL or healthy controls. Moreover, ADNL human epidermal equivalents were treated with tigecycline or MitoQ. We found that pyruvate and glucose were used as energy substrates by ADNL KCs. Increased mitochondrial oxidation of (very) long-chain fatty acids, associated with enhanced complexes I and II activities, was observed in ADNL KCs. Metabolomic analysis revealed increased tricarboxylic acid cycle turnover. Increased aerobic metabolism generated oxidative stress in ADNL KCs. ADNL human epidermal equivalents displayed increased mitochondrial function and an enhanced oxidative stress response compared with controls. Treatment of ADNL human epidermal equivalents with tigecycline or MitoQ largely corrected the AD profile, including high p-65 NF-κB, abnormal lamellar bodies, and cellular damage. Furthermore, we found that glycolysis supports but does not supersede mitochondrial metabolism in ADNL KCs. Thus, aerobic metabolism predominates in ADNL but leads to oxidative stress. Therefore, mitochondria could be a reservoir of potential therapeutic targets in atopic dermatitis.

Finding Gene Regulatory Networks in Psoriasis: Application of a Tree-Based Machine Learning Approach

Psoriasis is a chronic inflammatory skin disorder. Although it has been studied extensively, the molecular mechanisms driving the disease remain unclear. In this study, we utilized a tree-based machine learning approach to explore the gene regulatory networks underlying psoriasis. We then validated the regulators and their networks in an independent cohort. We identified some key regulators of psoriasis, which are candidates to serve as potential drug targets and disease severity biomarkers. According to the gene regulatory network that we identified, we suggest that interferon signaling represents a key pathway of psoriatic inflammation.

Immunological Pathomechanisms of Spongiotic Dermatitis in Skin Lesions of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic pruritic skin disease with a complex pathogenesis underlying its heterogeneous clinical phenotypes and endotypes. The skin manifestation of AD reflects the cytokine milieu of a type-2-dominant immunity axis induced by genetic predisposition, innate immunity dysregulation, epidermal barrier defects, and allergic inflammation. However, the detailed pathomechanism of eczematous dermatitis, which is the principal characteristic of AD, remains unclear. This review examines previous studies demonstrating research progress in this area and considers the immunological pathomechanism of “spongiotic dermatitis”, which is the histopathological hallmark of eczematous dermatitis. Studies in this field have revealed the importance of IgE-mediated delayed-type hypersensitivity, the Fas/Fas-ligand system, and cell-mediated cytotoxicity in inducing the apoptosis of keratinocytes in spongiotic dermatitis. Recent studies have demonstrated that, together with infiltrating CD4 T cells, IgE-expressing dendritic cells (i.e., inflammatory dendritic epidermal cells and Langerhans cells) that capture specific allergens (i.e., house dust mites) are present in the spongiotic epidermis of lichenified eczema in patients with IgE-allergic AD. These findings suggest that IgE-mediated delayed-type hypersensitivity plays a pivotal role in the pathogenesis of spongiotic dermatitis in the skin lesions of AD.

Cannabidiolic acid in Hemp Seed Oil Table Spoon and Beyond

Cannabidiolic acid (CBDA) is the main precannabinoid in industrial hemp. It represents a common constituent of hemp seed oil, but mainly abundant in the aerial parts of the plant (including their processing waste). Thus, the optimization of fast and low-cost purification strategies is mandatory, as well as a deep investigation on its nutraceutical and cosmeceutical properties. To this purpose, CBDA content in hemp seed oil is evaluated, and its recovery from wasted leaves is favorably achieved. The cytotoxicity screening towards HaCaT cells, by means of MTT, SRB and LDH release assays, suggested it was not able to decrease cell viability or perturb cell integrity up to 10 μM concentration. Thus, the ability of CBDA to differentially modulate the release of proinflammatory cytokines and chemokines mediators has been evaluated, finding that CBDA decreased IFN-γ, CXCL8, CXCL10, CCL2, CCL4 and CCL5, mostly in a dose-dependent manner, with 10 μM tested concentration exerting the highest activity. These data, together with those from assessing antimicrobial activity against Gram(+) and Gram(−) bacteria and the antibiofilm formation, suggest that CBDA is able to counteract the inflammatory response, also preventing bacteria colonization.

Mitochondrial calcium exchange in physiology and disease

The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.

Atopic dermatitis: molecular, cellular, and clinical aspects

Atopic dermatitis (AD) is a complicated, inflammatory skin disease, which numerous genetic and environmental factors play roles in its development. AD is categorized into different phenotypes and stages, although they are mostly similar in their pathophysiological aspects. Immune response alterations and structural distortions of the skin-barrier layer are evident in AD patients. Genetic makeup, lifestyle, and environment are also significantly involved in contextual factors. Genes involved in AD-susceptibility, including filaggrin and natural moisturizing, cause considerable structural modifications in the skin's lipid bilayer and cornified envelope. Additionally, the skin's decreased integrity and altered structure are accompanied by biochemical changes in the normal skin microflora's dysbiosis. The dynamic immunological responses, genetic susceptibilities, and structural modifications associated with AD's pathophysiology will be extensively discussed in this review, each according to the latest achievements and findings.

Inhibitory Effects of Euscaphic Acid in the Atopic Dermatitis Model by Reducing Skin Inflammation and Intense Pruritus

Atopic dermatitis (AD) is a complex and multifactorial skin disease characterized by skin inflammation and intense pruritus. There are many commercially available treatments such as topical corticosteroids and immunosuppressants to treat of AD, but their effectiveness is limited, and frequent use of these treatments can cause serious side effects. Therefore, the development of new therapeutic agents is necessary for the treatment of AD. Hence, an alternative agent that was derived from natural products that are effective and safe for AD treatment was investigated using experimental models. The biological activity of euscaphic acid has anti-inflammatory, anticoagulant, and antioxidant effects. Despite the various biomedical properties of euscaphic acid, its therapeutic effects on AD have not been well studied. In this study, we investigated the effects of euscaphic acid on skin inflammation and pruritus in AD mouse model. The effects of euscaphic acid were investigated in activated human epidermal keratinocytes and leukemia T lymphoblast cell lines, and Dermatophagoides farina extract and 2,4-dinitrochlorobenzene-induced AD mouse model. Euscaphic acid ameliorated AD properties, such as the expression of inflammatory cytokines and activation of transcription factors. In addition, euscaphic acid reduced critical factors for pruritus such as immunoglobulin E hyperproduction, mast cell invasion, and interleukin-33 expression. Taken together, euscaphic acid could be a potent therapeutic agent for the treatment of AD.

Effect of a combination of Korean red ginseng extract and probiotics on the prevention of atopic dermatitis in a murine model

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng C.A.Mey. (Korea red ginseng) has been used in Asia to treat inflammatory skin diseases. Recently, Korea red ginseng (KRG) is emerging as a good candidate for treating atopic dermatitis (AD) because of its anti-allergic and anti-inflammatory effects.

AIM OF THE STUDY

Despite much effort, no systemic prevention strategy has been established for AD currently. Therefore, the aim of this study was to determine the preventive effect of a combination of KRG extract and probiotics on AD-like skin lesions of mice.

MATERIALS AND METHODS

Forty NC/Nga mice were randomly divided into eight groups: Sham, AD control, Cyclosporine, KRG, Duolac ATP® (ATP), BYO Plant Origin Skin Probiotics (BYO), KRG + ATP, and KRG + BYO. Mice were administered orally with KRG and/or other agents using a gastric tube for 5 days prior to challenge with 1-chloro-2,4-dinitrobenzene (DNCB). AD-like skin lesions were induced by percutaneous challenge with DNCB on ears and backs of NC/Nga mice. Effects of each treatment were evaluated based on the following: Clinical severity score, ear thickness, transepidermal water loss (TEWL), total serum Immunoglobulin E (IgE) level, mRNA expression levels and immunohistochemistry analysis of IFN-γ, IL-4, and TSLP in cutaneous lesions.

RESULTS

TEWL, serum IgE level, and expression of immunohistopathologic markers were more improved in the group using KRG combined with probiotics than in the group using KRG or probiotics alone. ATP, KRG + ATP, and KRG + BYO groups showed reduced TEWL increase (ΔTEWL) at 48 h (p < 0.005). KRG + ATP showed a preventive effect on the increase of serum IgE level (p = 0.009). In immunohistopathologic analysis, KRG, ATP, BYO, KRG + ATP, and KRG + BYO groups showed significantly reduced expression levels of IFN-γ at 1 h, 6 h, and 48 h (all p < 0.05). KRG, ATP, BYO, and KRG + BYO groups showed reduced expression levels of IL-4 compared to the AD control group at 6 h and 24 h. KRG, ATP, BYO, KRG + ATP, and KRG + BYP groups showed significantly lower expression levels of TSLP than the AD control group at 1 h and 24 h.

CONCLUSION

KRG can suppress increases of allergic and inflammatory cytokines and increase of TEWL. A combination of KRG and probiotics might have better effects than KRG or probiotics alone for preventing an AD flare-up.

Accurate diagnosis of atopic dermatitis by combining transcriptome and microbiota data with supervised machine learning

Atopic dermatitis (AD) is a common skin disease in childhood whose diagnosis requires expertise in dermatology. Recent studies have indicated that host genes–microbial interactions in the gut contribute to human diseases including AD. We sought to develop an accurate and automated pipeline for AD diagnosis based on transcriptome and microbiota data. Using these data of 161 subjects including AD patients and healthy controls, we trained a machine learning classifier to predict the risk of AD. We found that the classifier could accurately differentiate subjects with AD and healthy individuals based on the omics data with an average F1-score of 0.84. With this classifier, we also identified a set of 35 genes and 50 microbiota features that are predictive for AD. Among the selected features, we discovered at least three genes and three microorganisms directly or indirectly associated with AD. Although further replications in other cohorts are needed, our findings suggest that these genes and microbiota features may provide novel biological insights and may be developed into useful biomarkers of AD prediction.

IFP35 Is a Relevant Factor in Innate Immunity, Multiple Sclerosis, and Other Chronic Inflammatory Diseases: A Review

Simple Summary

In this review, we focused on the emerging role of IFP35, a highly conserved leucine zipper protein from fish to humans, with a still unknown biological function. The considered literature indicates this protein as a key-pleiotropic factor reflecting JAK-STAT and DAMPs pathways activation in innate immunity-dependent inflammation, as well as in the physiology and general pathology of a wide range of phylogenetically distant organisms. These findings also indicate IFP35 as a biologically relevant molecule in human demyelinating diseases of the central nervous system, including Multiple Sclerosis, and other organ-specific chronic inflammatory disorders.

Abstract

Discovered in 1993 by Bange et al., the 35-kDa interferon-induced protein (IFP35) is a highly conserved cytosolic interferon-induced leucine zipper protein with a 17q12-21 coding gene and unknown function. Belonging to interferon stimulated genes (ISG), the IFP35 reflects the type I interferon (IFN) activity induced through the JAK-STAT phosphorylation, and it can homodimerize with N-myc-interactor (NMI) and basic leucine zipper transcription factor (BATF), resulting in nuclear translocation and a functional expression. Casein kinase 2-interacting protein-1 (CKIP-1), retinoic acid-inducible gene I (RIG-I), and laboratory of genetics and physiology 2 Epinephelus coioides (EcLGP2) are thought to regulate IFP35, via the innate immunity pathway. Several in vitro and in vivo studies on fish and mammals have confirmed the IFP35 as an ISG factor with antiviral and antiproliferative functions. However, in a mice model of sepsis, IFP35 was found working as a damage associated molecular pattern (DAMP) molecule, which enhances inflammation by acting in the innate immune-mediated way. In human pathology, the IFP35 expression level predicts disease outcome and response to therapy in Multiple Sclerosis (MS), reflecting IFN activity. Specifically, IFP35 was upregulated in Lupus Nephritis (LN), Rheumatoid Arthritis (RA), and untreated MS. However, it normalized in the MS patients undergoing therapy. The considered data indicate IFP35 as a pleiotropic factor, suggesting it as biologically relevant in the innate immunity, general pathology, and human demyelinating diseases of the central nervous system.

Prevention of Atopic Dermatitis in Mice by Lactobacillus Reuteri Fn041 Through Induction of Regulatory T Cells and Modulation of the Gut Microbiota

SCOPE

The development of atopic dermatitis (AD) in infants is closely related to the lagging development of intestinal microbiota, including that inoculated by breast milk bacteria, and immune development. Lactobacillus reuteri Fn041 is a secretory immunoglobulin A (sIgA) -coated bacterium derived from human milk.

METHODS AND RESULTS

We intervened with L. reuteri Fn041 in maternal and offspring BALB/C mice during late gestation and lactation and after weaning of the pups, respectively. AD was then induced with MC903. L. reuteri Fn041 significantly suppressed AD symptoms such as skin swelling, mast cell and eosinophil infiltration. This effect was attributed to the regulation of the systemic Th1 and Th2 cytokine ratios and the promotion of CD4⁺ CD25⁺ Foxp3⁺ regulatory T cell proliferation in mesenteric lymph nodes. It is also associated with the regulation of intestinal microbiota, particularly promoting Lactobacillus and Akkermansia.

CONCLUSIONS

Our study strengthens the understanding that breast milk-derived sIgA coated potential probiotics are involved in the development of infant intestinal microbiota, thus promoting immune development and preventing allergic diseases, and expanding the knowledge of breast milk sIgA and bacterial interactions on infant immune development. This article is protected by copyright. All rights reserved.

Rare variant analysis in eczema identifies exonic variants in DUSP1, NOTCH4 and SLC9A4

Previous genome-wide association studies revealed multiple common variants involved in eczema but the role of rare variants remains to be elucidated. Here, we investigate the role of rare variants in eczema susceptibility. We meta-analyze 21 study populations including 20,016 eczema cases and 380,433 controls. Rare variants are imputed with high accuracy using large population-based reference panels. We identify rare exonic variants in DUSP1, NOTCH4, and SLC9A4 to be associated with eczema. In DUSP1 and NOTCH4 missense variants are predicted to impact conserved functional domains. In addition, five novel common variants at SATB1-AS1/KCNH8, TRIB1/LINC00861, ZBTB1, TBX21/OSBPL7, and CSF2RB are discovered. While genes prioritized based on rare variants are significantly up-regulated in the skin, common variants point to immune cell function. Over 20% of the single nucleotide variant-based heritability is attributable to rare and low-frequency variants. The identified rare/low-frequency variants located in functional protein domains point to promising targets for novel therapeutic approaches to eczema.

Genetic studies of eczema to date have mostly explored common genetic variation. Here, the authors perform a large meta-analysis for common and rare variants and discover 8 loci associated with eczema. Over 20% of the heritability of the condition is attributable to rare variants.

A Microbiome-Derived Peptide Induces Apoptosis of Cells from Different Tissues

Apoptosis is a programmed cell death involved in embryogenesis and tissue homeostasis under physiological conditions. However, abnormalities in the process of apoptosis are implicated in the pathogenesis of various diseases. The human microbiota may release products that induce apoptosis of host cells. We recently identified a novel microbiome-derived peptide called corisin that worsens lung fibrosis by inducing apoptosis of lung epithelial cells. We hypothesized that corisin and a corisin-like peptide might also induce apoptosis of cells from different tissues. We cultured podocytes, renal tubular epithelial cells, keratinocytes, retinal and intestinal cells treated with corisin and evaluated apoptosis by flow cytometry and Western blotting. Although at different grades, flow cytometry analysis and Western blotting showed that corisin and a corisin-like peptide induced apoptosis of podocytes, keratinocytes, tubular epithelial cells, retinal, and intestinal cells. In addition, we found that corisin synergistically enhances the proapoptotic activity of transforming growth factor-β1 on podocytes. In conclusion, these results suggest that corisin and corisin-like peptides may play a role in the pathogenesis of disease in different organs by promoting apoptosis of parenchymal cells.

MiR-146b-5p targets IFI35 to inhibit inflammatory response and apoptosis via JAK1/STAT1 signalling in lipopolysaccharide-induced glomerular cells

The dysregulated microRNAs (miRNAs) are implicated in the malignancy of lupus nephritis (LN). This work aims to analyse the effect and mechanism of miR-146b-5p in lipopolysaccharides (LPS)-induced model of LN in vitro. The serum samples of LN patients and normal volunteers were collected. HK-2 cells were challenged via LPS. miR-146b-5p and interferon-induced protein 35 (IFI35) abundances were detected via quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. The inflammatory response was assessed via inflammatory cytokines levels via qRT-PCR and enzyme-linked immunosorbent assay. Cell apoptosis was analysed via flow cytometry and apoptotic protein levels. The protein levels of JAK1/STAT1 signalling were detected via western blot. The relationship of miR-146b-5p and IFI35 was analysed via bioinformatics and dual-luciferase reporter assays. This study revealed that miR-146b-5p level was declined and IFI35 abundance was elevated in serum of LN patients and LPS-challenged HK-2 cells. Functionally, IFI35 overexpression promoted LPS-caused inflammatory response and cell apoptosis, and knockdown of IFI35 caused an opposite trend. Meanwhile, miR-146b-5p targeted IFI35 to suppress inflammatory response and cell inflammatory response and apoptosis via inactivating the JAK1/STAT1 pathway. MiR-146b-5p suppressed inflammatory response and cell apoptosis by IFI35 mediated-JAK1/STAT1 signalling in HK-2 cells, which provided a new mechanism for understanding the pathogenesis of LN.

Cytokines and apoptosis in atopic dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease. AD affects 10-20% of children worldwide and persists into adulthood in a minority of cases, affecting approximately 2-3% of the adult population, with an increased prevalence over the past decades in developed countries. Atopy is a genetic tendency to overproduce IgE class antibodies in response to common antigens found in the environment. Concurrence of different atopy such as allergic rhinitis or asthma in children with AD is estimated at 80%. AD is characterized by a vicious cycle of an allergic immune response. The emerging picture of the AD is a complex disorder with barrier dysfunction, immunological, genetic and environmental factors all playing key roles. Patients with severe or persistent disease and their families experience significant impairment in their quality of life, and in addition, AD places a heavy economic burden on society as a whole. Pathogenesis, the role of the epidermal barrier, mechanisms of cells apoptosis, the role of T cells and cytokines in AD are discussed in this article.

Childhood atopic dermatitis as a precursor for developing attention deficit/hyperactivity disorder

Atopic dermatitis (AD) is a skin disease characterized by chronic inflammatory condition that shows hallmark presentations in terms of sleep disturbances, pruritus, and psychological stress, and an association with increased attention deficit/hyperactivity disorder (ADHD) risk. A number of studies have suggested for the co-occurrence of the two diseased conditions. In terms of global prevalence, AD and ADHD almost exhibit a parallel increment according to epidemiological data. In addition, recent reports indicate AD to show a temporal association with later onset of ADHD. Although several studies suggest for the potential link between AD and ADHD, currently there is no definitive answer to this regard. Furthermore, epidemiological evidence of co-occurrence does not ascertain a pathophysiological link between the two conditions. The pathophysiological basis behind the association of AD and ADHD also remain poorly elucidated. The objective of this review is to present an extensive account of AD and associated comorbidities with a special attention toward ADHD as well as to elaborate on the mechanisms underlying their association. The review can provide healthcare providers with the recent updates on AD-ADHD association and help them while dealing with such patients. In general, AD and ADHD show a positive association in majority of the cross-sectional studies. However, large longitudinal studies are required to draw any conclusion on the temporal nature of such association.

Current Insights into Immunology and Novel Therapeutics of Atopic Dermatitis

Atopic dermatitis (AD) is one of the most prevalent inflammatory disease among non-fatal skin diseases, affecting up to one fifth of the population in developed countries. AD is characterized by recurrent pruritic and localized eczema with seasonal fluctuations. AD initializes the phenomenon of atopic march, during which infant AD patients are predisposed to progressive secondary allergies such as allergic rhinitis, asthma, and food allergies. The pathophysiology of AD is complex; onset of the disease is caused by several factors, including strong genetic predisposition, disrupted epidermal barrier, and immune dysregulation. AD was initially characterized by defects in the innate immune system and a vigorous skewed adaptive Th2 response to environmental agents; there are compelling evidences that the disorder involves multiple immune pathways. Symptomatic palliative treatment is the only strategy to manage the disease and restore skin integrity. Researchers are trying to more precisely define the contribution of different AD genotypes and elucidate the role of various immune axes. In this review, we have summarized the current knowledge about the roles of innate and adaptive immune responsive cells in AD. In addition, current and novel treatment strategies for the management of AD are comprehensively described, including some ongoing clinical trials and promising therapeutic agents. This information will provide an asset towards identifying personalized targets for better therapeutic outcomes.

Chrysin Inhibits NF-κB-Dependent CCL5 Transcription by Targeting IκB Kinase in the Atopic Dermatitis-Like Inflammatory Microenvironment

Chrysin (5,7-dihydroxyflavone) is a natural polyphenolic compound that induces an anti-inflammatory response. In this study, we investigated the molecular mechanism underlying the chrysin-induced suppression of C-C motif chemokine ligand 5 (CCL5) gene expression in atopic dermatitis (AD)-like inflammatory microenvironment. We showed that chrysin inhibited CCL5 expression at the transcriptional level through the suppression of nuclear factor kappa B (NF-κB) in the inflammatory environment. Chrysin could bind to the ATP-binding pocket of the inhibitor of κB (IκB) kinase (IKK) and, subsequently, prevent IκB degradation and NF-κB activation. The clinical efficacy of chrysin in targeting IKK was evaluated in 2,4-dinitrochlorobenzene-induced skin lesions in BALB/c mice. Our results suggested that chrysin prevented CCL5 expression by targeting IKK to reduce the infiltration of mast cells to the inflammatory sites and at least partially attenuate the inflammatory responses. These findings suggested that chrysin might be useful as a platform for the design and synthesis of small-molecule IKK-targeting drugs for the treatment of chronic inflammatory diseases, such as AD.

NickFect type of cell-penetrating peptides present enhanced efficiency for microRNA-146a delivery into dendritic cells and during skin inflammation

MicroRNAs (miRNAs) are post-transcriptional gene expression regulators with potential therapeutic applications. miR-146a is a negative regulator of inflammatory processes in both tissue-resident and specialized immune cells and may therefore have therapeutic effect in inflammatory skin diseases. PepFect (PF) and NickFect (NF) type of cell-penetrating peptides (CPPs) have previously been shown to deliver miRNA mimics and/or siRNAs into cell cultures and in vivo. Here, we first demonstrate that selected PF- and NF-type of CPPs support delivery of fluorescent labelled miRNA mimics into keratinocytes (KCs) and dendritic cells (DCs). Second, we show that both PF- and NF-miR-146a nanocomplexes were equally effective in KCs, while NFs were more efficient in DCs as assessed by downregulation of miR-146a-influenced genes. None of miRNA nanocomplexes with the tested CPPs influenced the viability of KCs and DCs nor caused activation of DCs according to CD86 and CD83 markers. Transmission electron microscopy analysis with Nanogold-labelled miR-146a mimics and assessment of endocytic trafficking pathways revealed endocytosis as an active route of delivery in both KCs and DCs for all tested CPPs. However, consistent with the higher efficiency, NF-delivered miR-146a was detected more often outside endosomes in DCs. Finally, pre-injection of NF71:miR-146a nanocomplexes was confirmed to suppress inflammatory responses in a mouse model of irritant contact dermatitis as shown by reduced ear swelling response and downregulation of pro-inflammatory cytokines, including IL-6, IL-1β, IL-33 and TNF-α. In conclusion, NF71 efficiently delivers miRNA mimics into KCs as well as DCs, and therefore may have advantage in therapeutic delivery of miRNAs in case of inflammatory skin diseases.

MCP-2/CCL8 Level Associated With Suicidal Ideation in Elderly Men With Major Depression

OBJECTIVES

We compared serum levels of chemokines between male elders with major depressive disorder (MDD) and healthy controls, verifying whether any difference exists in the levels of these mediators between those with and without current suicidal ideation (SI).

METHODS

We enrolled 145 male elders aged 65 or older and analyzed 40 chemokines in patients with MDD with SI (n = 24) and without SI (n = 23), as well as healthy controls (n = 98).

RESULTS

The patients with MDD with SI presented higher levels of MCP-2/CCL8 (p < 0.001) compared with the patients with MDD without SI and the healthy controls.

CONCLUSIONS

Current findings suggest a potential role of MCP-2/CCL8 in suicidality among elderly males with depression.

Mechanisms of innate events during skin reaction following intradermal injection of seasonal influenza vaccine

The skin plays a crucial role in host defences against microbial attack and the innate cells must provide the immune system with sufficient information to organize these defences. This unique feature makes the skin a promising site for vaccine administration. Although cellular innate immune events during vaccination have been widely studied, initial events remain poorly understood. Our aim is to determine molecular biomarkers of skin innate reaction after intradermal (i.d.) immunization. Using an ex vivo human explant model from healthy donors, we investigated by NanoLC-MS/MS analysis and MALDI-MSI imaging, to detect innate molecular events (lipids, metabolites, proteins) few hours after i.d. administration of seasonal trivalent influenza vaccine (TIV). This multimodel approach allowed to identify early molecules differentially expressed in dermal and epidermal layers at 4 and 18 h after TIV immunization compared with control PBS. In the dermis, the most relevant network of proteins upregulated were related to cell-to-cell signalling and cell trafficking. The molecular signatures detected were associated with chemokines such as CXCL8, a chemoattractant of neutrophils. In the epidermis, the most relevant networks were associated with activation of antigen-presenting cells and related to CXCL10. Our study proposes a novel step-forward approach to identify biomarkers of skin innate reaction. SIGNIFICANCE: To our knowledge, there is no study analyzing innate molecular reaction to vaccines at the site of skin immunization. What is known on skin reaction is based on macroscopic (erythema, redness…), microscopic (epidermal and dermal tissues) and cellular events (inflammatory cell infiltrate). Therefore, we propose a multimodal approach to analyze molecular events at the site of vaccine injection on skin tissue. We identified early molecular networks involved biological functions such cell migration, cell-to-cell interaction and antigen presentation, validated by chemokine expression, in the epidermis and dermis, then could be used as early indicator of success in immunization.

Bleomycin hydrolase regulates the release of chemokines important for inflammation and wound healing by keratinocytes

Bleomycin hydrolase (BLMH) is a well-conserved cysteine protease widely expressed in several mammalian tissues. In skin, which contains high levels of BLMH, this protease is involved in the degradation of citrullinated filaggrin monomers into free amino acids important for skin hydration. Interestingly, the expression and activity of BLMH is reduced in patients with atopic dermatitis (AD) and psoriasis, and BLMH knockout mice acquire tail dermatitis. Apart from its already known function, we have discovered a novel role of BLMH in the regulation of inflammatory chemokines and wound healing. We show that lowered BLMH levels in keratinocytes result in increased release of the pro-inflammatory chemokines CXCL8 and GROα, which are upregulated in skin from AD patients compared to healthy individuals. Conditioned media from keratinocytes expressing low levels of BLMH increased chemotaxis by neutrophils and caused a delayed wound healing in the presence of low-level TNFα. This defective wound healing was improved by blocking the shared receptor of CXCL8 and GROα, namely CXCR2, using a specific receptor antagonist. Collectively, our results present a novel function of BLMH in regulating the secretion of chemokines involved in inflammation and wound healing in human keratinocytes.

Proof-of-concept clinical trial of etokimab shows a key role for IL-33 in atopic dermatitis pathogenesis

Targeted inhibition of cytokine pathways provides opportunities to understand fundamental biology in vivo in humans. The IL-33 pathway has been implicated in the pathogenesis of atopy through genetic and functional associations. We investigated the role of IL-33 inhibition in a first-in-class phase 2a study of etokimab (ANB020), an IgG1 anti-IL-33 monoclonal antibody, in patients with atopic dermatitis (AD). Twelve adult patients with moderate to severe AD received a single systemic administration of etokimab. Rapid and sustained clinical benefit was observed, with 83% achieving Eczema Area and Severity Index 50 (EASI50), and 33% EASI75, with reduction in peripheral eosinophils at day 29 after administration. We noted significant reduction in skin neutrophil infiltration after etokimab compared with placebo upon skin challenge with house dust mite, reactivity to which has been implicated in the pathogenesis of AD. We showed that etokimab also inhibited neutrophil migration to skin interstitial fluid in vitro. Besides direct effects on neutrophil migration, etokimab revealed additional unexpected CXCR1-dependent effects on IL-8-induced neutrophil migration. These human in vivo findings confirm an IL-33 upstream role in modulating skin inflammatory cascades and define the therapeutic potential for IL-33 inhibition in human diseases, including AD.

Pathophysiology of Atopic Dermatitis and Psoriasis: Implications for Management in Children

Atopic dermatitis (AD) and psoriasis are chronic inflammatory skin diseases associated with a significant cutaneous and systemic burden of disease as well as a poor health-related quality of life. Here, we review the complex pathophysiology of both AD and psoriasis and discuss the implications for treatment with current state-of-the-art and emerging topical and systemic therapies. Both AD and psoriasis are caused by a complex combination of immune dysregulation, skin-barrier disruption, genetic factors, and environmental influences. Previous treatments for both diseases were limited to anti-inflammatory agents that broadly suppress inflammation. Emerging insights into relevant pathways, including recognition of the role of T-helper type 2 driven inflammation in AD and T-helper 1 and 17 driven inflammation in psoriasis, have led to a therapeutic revolution. There are a number of novel treatment options available for AD and psoriasis with many more currently under investigation.

Transcriptional profiling of lactic acid treated reconstructed human epidermis reveals pathways underlying stinging and itch

The incidence of sensitive skin with stinging and itch following chemical exposure in products such as cosmetics is increasing, but molecular mechanisms underlying this pathophysiology remain understudied. Here we performed transcriptional analysis of reconstructed human epidermis (RHE) 1, 6, and 24 h following topical lactic acid (LA) application, a known inducer of the sensitive skin reaction. Since little is known about the specific role of keratinocyte transcriptional changes in mediating stinging and itch, we performed pathway analysis using several publically available databases and then focused on significantly changed transcripts involved in stress responses and itch signaling using the Comparative Toxicogenomics Database. LA treatment induced damage-associated genes HSPA1A, DDIT3, IL1A, and HMGB2. Neurotrophic factors including BDNF, ARTN, PGE2, and chemokines were also upregulated. Stimulation of the RHE with 5% LA did not reduce cell viability, but reduced the trans-epidermal electric resistance, suggesting barrier dysfunction. Accordingly, skin barrier formation genes such as filaggrins (FLG, FLG2) and corneodesmosin (CDSN) were downregulated. To our knowledge, this is the first study focusing on transcriptional changes underlying the stinging response of keratinocytes upon LA stimulation. While follow-up research is needed, this study provides new insight into the mechanisms underlying the sensitive skin reaction.

Comparison of the Inhibitory Activities of 5,6-Dihydroergosterol Glycoside α- and β-Anomers on Skin Inflammation

Chronic skin inflammatory diseases, such as atopic dermatitis, are associated with a dysfunctional skin barrier due to an increase in various inflammatory stimuli, for instance inflammatory cytokines and chemokines. In particular, CCL17 and CCL22 expression is increased in patients with chronic skin inflammation. In this study, we synthesized several α- and β-anomers of dihydroergosterol (DHE)-glycosides and assessed their effects on CCL17 and CCL22 expression. We confirmed that the β-anomers of DHE-glycosides were superior to α-anomers of DHE-glycosides in inhibiting CCL17 and CCL22 mRNA and protein expression. In addition, we determined that DHE-glycoside β-anomers showed strong inhibitory activity towards pro-inflammatory cytokine mRNA and protein expression, including that of TNF-α, IL-6, and IL-1β- in stimulated HaCaT cells. These results imply that DHE-glycoside α- and β-anomers should be separated during synthesis of drugs for chronic skin inflammation. Our results also suggest that β-anomers of DHE-glycosides may play an important role as new drugs for chronic skin inflammation because of their ability to inhibit the skin inflammatory biomarker proteins CCL17 and CCL22.