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

Early itch relief with upadacitinib predicts later skin clearance in Atopic dermatitis

BACKGROUND

Though Janus kinase inhibitors such as upadacitinib rapidly relieve itch in atopic dermatitis (AD) patients, how early itch relief impacts later skin clearance is not examined.

OBJECTIVES

This study aims to determine if early itch relief by upadacitinib could predict complete skin clearance in later phases.

METHODS

This retrospective study involved 105 patients with moderate-to-severe AD treated with upadacitinib 15 mg/day. Eczema area and severity index (EASI), atopic dermatitis control tool, and achievement rate of EASI 100 were evaluated at weeks 4, 12, and 24. The threshold of early peak pruritus-numerical rating scale (PP-NRS) predicting later skin clearance was assessed by area under the receiver-operating characteristic curve, and predictors for EASI 100 achievement were determined by logistic regression analysis.

RESULTS

The rate of achieving EASI 100 at week 24 was extremely higher in patients who achieved week 2 PP-NRS ≤ 1 (42.9%) than in non-achievers (1.4%). The logistic regression analysis showed that the achievement of week 2 PP-NRS ≤ 1 and low body mass index were associated with achievement of EASI 100 at weeks 12 and 24.

CONCLUSIONS

The achievement of week 2 PP-NRS ≤ 1 may predict later skin clearance in upadacitinib treatment.

The causal relationship and potential mediators between plasma lipids and atopic dermatitis: a bidirectional two-sample, two-step mendelian randomization

BACKGROUND

Observational studies have indicated that the plasma lipid profiles of patients with atopic dermatitis show significant differences compared to healthy individuals. However, the causal relationship between these differences remains unclear due to the inherent limitations of observational studies. Our objective was to explore the causal effects between 179 plasma lipid species and atopic dermatitis, and to investigate whether circulating inflammatory proteins serve as mediators in this causal pathway.

METHODS

We utilized public genome-wide association studies data to perform a bidirectional two-sample, two-step mendelian randomization study. The inverse variance-weighted method was adopted as the primary analysis technique. MR-Egger and the weighted median were used as supplementary analysis methods. MR-PRESSO, Cochran's Q test, and MR-Egger intercept test were applied for sensitivity analyses to ensure the robustness of our findings.

RESULTS

The Mendelian randomization analysis revealed that levels of Phosphatidylcholine (PC) (18:1_20:4) (OR: 0.950, 95% CI: 0.929-0.972, p = 6.65 × 10- 6), Phosphatidylethanolamine (O-18:1_20:4) (OR: 0.938, 95% CI: 0.906-0.971, p = 2.79 × 10- 4), Triacylglycerol (TAG) (56:6) (OR: 0.937, 95% CI: 0.906-0.969, p = 1.48 × 10- 4) and TAG (56:8) (OR: 0.918, 95% CI: 0.876-0.961, p = 2.72 × 10- 4) were inversely correlated with the risk of atopic dermatitis. Conversely, PC (18:1_20:2) (OR: 1.053, 95% CI: 1.028-1.079, p = 2.11 × 10- 5) and PC (O-18:1_20:3) (OR: 1.086, 95% CI: 1.039-1.135, p = 2.47 × 10- 4) were positively correlated with the risk of atopic dermatitis. The results of the reverse directional Mendelian randomization analysis indicated that atopic dermatitis exerted no significant causal influence on 179 plasma lipid species. The level of circulating IL-18R1 was identified as a mediator for the increased risk of atopic dermatitis associated with higher levels of PC (18:1_20:2), accounting for a mediation proportion of 9.07%.

CONCLUSION

Our research suggests that plasma lipids can affect circulating inflammatory proteins and may serve as one of the pathogenic factors for atopic dermatitis. Targeting plasma lipid levels as a treatment for atopic dermatitis presents a potentially novel approach.

Higher-order sensorimotor circuit of the whole-brain functional network involved in pruritus regulation in atopic dermatitis

BACKGROUND

Little is known about the neural mechanisms underlying pruritus regulation in Atopic dermatitis (AD).

OBJECTIVE

To investigate the functional changes of the resting-state whole brain network of AD participants and the mechanisms by which they were involved in pruritus regulation.

METHOD

Based on the functional magnetic resonance imaging data from 19 AD participants and 37 healthy controls (HC), a graph-theoretical measure of degree centrality (DC) conjoined with a voxel-level seed-based functional connectivity (FC) method was used to identify abnormal higher-order nodes and the functionally relevant circuit in AD participants compared to healthy controls (HC).

RESULTS

Of 64 participants screened, 19 AD participants (12M/7F, median [IQR] age, 27 [14] years) and 36 HCs (13M/23F, median [IQR] age, 20 [1] years) were enrolled. DC values of the left superior frontal gyrus (LSFG) increased in AD participants and exhibited a negative correlation with the SCORAD score (r = -0.561, p = 0.012) compared with HC. In the FC analysis with LSFG as the seed, FC values of several sensory and motor regions increased in AD participants, highly overlapping with the anatomical distribution of the inferior fronto-occipital fascicle (IFOF). AD participants with severe pruritus exhibited lower levels of DC (T = -2.316, p = 0.033) and FC between the LSFG and left insula (T = -2.203, p = 0.042) than those with mild-to- moderate pruritus.

CONCLUSIONS AND RELEVANCE

LSFG was involved in pruritus regulation in AD by forming a high-order sensorimotor circuit through the IFOF, a white matter fascicle that proved to provide multimodal integration in motor control and sensory information processing. These results offer more mechanism-guided treatment targets for severe pruritus in AD.

A quantitative systems pharmacology workflow toward optimal design and biomarker stratification of atopic dermatitis clinical trials

BACKGROUND

The development of atopic dermatitis (AD) drugs is challenged by many disease phenotypes and trial design options, which are hard to explore experimentally.

OBJECTIVE

We aimed to optimize AD trial design using simulations.

METHODS

We constructed a quantitative systems pharmacology model of AD and standard of care (SoC) treatments and generated a phenotypically diverse virtual population whose parameter distribution was derived from known relationships between AD biomarkers and disease severity and calibrated using disease severity evolution under SoC regimens.

RESULTS

We applied this workflow to the immunomodulator OM-85, currently being investigated for its potential use in AD, and calibrated the investigational treatment model with the efficacy profile of an existing trial (thereby enriching it with plausible marker levels and dynamics). We assessed the sensitivity of trial outcomes to trial protocol and found that for this particular example the choice of end point is more important than the choice of dosing regimen and patient selection by model-based responder enrichment could increase the expected effect size. A global sensitivity analysis revealed that only a limited subset of baseline biomarkers is needed to predict the drug response of the full virtual population.

CONCLUSIONS

This AD quantitative systems pharmacology workflow built around knowledge of marker-severity relationships as well as SoC efficacy can be tailored to specific development cases to optimize several trial protocol parameters and biomarker stratification and therefore has promise to become a powerful model-informed AD drug development and personalized medicine tool.

Atopic Dermatitis Itch: Scratching for an Explanation

Chronic pruritus is a cardinal symptom of atopic dermatitis (AD). The mechanisms underlying atopic itch involve intricate crosstalk among skin, immune components, and neural components. In this review, we explore these mechanisms, focusing on key players and interactions that induce and exacerbate itch. We discuss the similarities and differences between pruritus and pain in patients with AD as well as the relationship between pruritus and factors such as sweat and the skin microbiome. Furthermore, we explore novel targets that could provide significant itch relief in these patients as well as exciting future research directions to better understand atopic pruritus in darker skin types.

Effects of abrocitinib on pruritus and eczema symptoms and tolerance in patients with moderate‑to‑severe atopic dermatitis in randomized, double‑blind and placebo‑controlled trials: A systematic review and a meta‑analysis

Abrocitinib is a highly selective Janus kinase 1 (JAK1) inhibitor that can block a multitude of inflammatory signaling pathways that underlie atopic dermatitis (AD). In addition, abrocitinib inhibits JAK1 signaling in sensory neurons to alleviate acute and chronic pruritus during AD. However, substantial variations in efficacy and safety risks remain due to variations in doses applied in clinical use. Therefore for the present study, differences in the efficacy and tolerability of 100 and 200 mg abrocitinib for treating pruritus and eczema symptoms in patients with moderate-to-severe AD were evaluated compared with placebo. Specifically, randomized controlled trials (RCTs) of abrocitinib compared with placebo for the treatment of moderate-to-severe AD were searched on Pubmed, E.B. Stephens Company, China National Knowledge Infrastructure, Wanfang Medical network, Web of Science and related Clinical Trials Registry up to November 2023. In total, two researchers evaluated the quality of the included literature according to the Cochrane Handbook of Systematic Reviews. RevMan 5.3 software was used to conduct a meta-analysis of the efficacy and safety indicators in a cross-comparison of the effects exerted by placebo and 100 and 200 mg abrocitinib. A total of 1,825 patients with moderate-to-severe AD were included across five double-blind, placebo RCTs. Compared with the placebo group, during the double-blind trial period, significant improvements were observed in the investigator's global assessment score, response rate of eczema area and severity index (EASI)-50, EASI-75, EASI-90 and pruritus numerical rating scale (P-NRS) in the 100 and 200 mg abrocitinib groups (P<0.05). However, pairwise control analysis of the 100 and 200 mg group yielded significant differences (P<0.05) in all of the aforementioned therapeutic indicators except for the P-NRS score. In terms of safety, compared with the placebo group, there were significantly higher incidence of nausea, upper respiratory tract viral infection, infections and infestations in the 100 mg abrocitinib group (P<0.05). In addition, there were significantly higher incidence of nausea, gastrointestinal disorder, headache and dizziness in the 200 mg group (P<0.05). There were also significant differences in the incidence of nausea, gastrointestinal disorder and dizziness between the 100 and 200 mg groups (P<0.05). For patients with moderate-to-severe AD, oral administration of 100 or 200 mg abrocitinib once/day was concluded to ameliorate skin pruritus and eczema symptoms to varying degrees, with the efficacy significantly superior at the 200 mg dose. However, the risk of a number of adverse reactions, such as headache, dizziness, nausea and gastrointestinal dysfunction, is also significantly increased. Therefore, patients should be made aware of the risk of adverse drug effects prior to the administration of long-term high abrocitinib doses. Furthermore, large-scale, multi-center, rigorous clinical trials remain necessary to validate the findings from the present study.

Unveiling Immunomodulatory Effects of Euglena gracilis in Immunosuppressed Mice: Transcriptome and Pathway Analysis

The immunomodulatory effects of Euglena gracilis (Euglena) and its bioactive component, β-1,3-glucan (paramylon), have been clarified through various studies. However, the detailed mechanisms of the immune regulation remain to be elucidated. This study was designed not only to investigate the immunomodulatory effects but also to determine the genetic mechanisms of Euglena and β-glucan in cyclophosphamide (CCP)-induced immunosuppressed mice. The animals were orally administered saline, Euglena (800 mg/kg B.W.) or β-glucan (400 mg/kg B.W.) for 19 days, and CCP (80 mg/kg B.W.) was subsequently administered to induce immunosuppression in the mice. The mice exhibited significant decreases in body weight, organ weight, and the spleen index. However, there were significant improvements in the spleen weight and the spleen index in CCP-induced mice after the oral administration of Euglena and β-glucan. Transcriptome analysis of the splenocytes revealed immune-related differentially expressed genes (DEGs) regulated in the Euglena- and β-glucantreated groups. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that pathways related with interleukin (IL)-17 and cAMP play significant roles in regulating T cells, B cells, and inflammatory cytokines. Additionally, Ptgs2, a major inflammatory factor, was exclusively expressed in the Euglena-treated group, suggesting that Euglena's beneficial components, such as carotenoids, could regulate these genes by influencing immune lymphocytes and inflammatory cytokines in CCP-induced mice. This study validated the immunomodulatory effects of Euglena and highlighted its underlying mechanisms, suggesting a positive contribution to the determination of phenotypes associated with immune-related diseases and the research and development of immunotherapies.

Paediatric Atopic Dermatitis: The Unexpected Impact on Life with a Specific Look at the Molecular Level

Atopic dermatitis (AD) is a condition with a multifactorial aetiology that affects the skin. It most often begins at preschool age and involves the skin. The disease's main symptom is intense itching, which occurs especially at night and affects the child's sleep, negatively impacting the quality of life of affected children and, consequently, their families. The difficulty in resting during the night leads to many problems during the day, particularly behavioural disorders and difficulties in paying attention at school, which results in learning impairment. The unexpected symptoms of AD are caused by pathophysiological processes that include many molecular pathways and inflammatory cytokines such as IL-31, IL-1, IL-2, TNF-a, and IL-6. Drawing on a comprehensive review of the literature in PubMed/MedLine, our review offers an in-depth exploration of both the psychosocial impacts of AD and the molecular processes that contribute to this disorder.

Evaluation of Artemisia dubia folium extract-mediated immune efficacy through developing a murine model for acute and chronic stages of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a biphasic type of skin inflammation characterized by a predominance of type-2 (TH2) and type-1 (TH1) helper T cell-biased immune responses at the acute and persistent chronic phases, respectively. The present study was aimed to evaluate the efficacy of Artemisia dubia folium extract (ADFE) on AD-like skin lesions through developing a murine model for acute and chronic stages of AD. To induce acute phase AD, the dorsal skin of BALB/c mice was sensitized twice a week with 1% 2, 4-dinitrochlorobenzene (DNCB), followed by challenge (twice) in the following week with 0.2% DNCB. To induce persistent chronic AD, some mice were challenged twice a week for 4 more weeks. After the second challenge, the dorsal skin was exposed to 3% ADFE (five times per week) for 2 weeks (acute phase) or 4 weeks (persistent chronic phase).

RESULTS

The paradigm of TH2 or TH1 predominance at the acute and chronic phase, respectively, was observed in this mouse model. During the acute phase, we observed an increased IL-4/IFN-γ ratio in splenic culture supernatants, an increased IgG1/IgG2a ratio in serum, and elevated serum IgE levels; however, the skew toward TH2 responses was diminished during the chronic stage. Compared with vehicle controls, ADFE reduced the IL-4/IFN-γ and IgG1/IgG2a ratios in acute AD, but both ratios increased during the chronic stage.

CONCLUSIONS

Our results suggest that ADFE concomitantly suppresses the TH2 predominant response in acute AD, as well as the TH1 predominant response in chronic AD. Thus, ADFE is a candidate therapeutic for AD.

Extracts of Grifola frondosa inhibit the MAPK signaling pathways involved in keratinocyte inflammation and ameliorate atopic dermatitis

BACKGROUND/OBJECTIVES

Grifola frondosa, commonly referred to as the maitake mushroom, has been studied extensively to explore its potential health benefits. However, its anti-inflammatory effects in skin disorders have not been sufficiently elucidated. This study aimed to elucidate the anti-inflammatory role of the ethanol extract of G. frondosa in atopic dermatitis (AD) using in vivo and in vitro models.

MATERIALS/METHODS

We investigated its impact on skin and spleen inflammatory responses in Dermatophagoides farinae extract (DFE)/1-chloro-2,4 dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in a mouse model. Additionally, we determined the immunosuppressive response and mechanism of G. frondosa by inducing atopic-like immune reactions in keratinocytes through tumor necrosis factor (TNF)-α/interferon (IFN)-γ stimulation.

RESULTS

Our study revealed that G. frondosa ameliorates clinical symptoms in an AD-like mouse model. These effects contributed to the suppression of Th1, Th2, Th17, and Th22 immune responses in the skin and spleen, leading to protection against cutaneous inflammation. Furthermore, G. frondosa inhibited the production of antibodies immunoglobulin (Ig)E and IgG2a in the serum of AD mice. Importantly, the inhibitory effect of G. frondosa on inflammatory cytokines in TNF-α/IFN-γ-stimulated AD-like keratinocytes was associated with the suppression of MAPK (Mitogen Activated Protein Kinase) pathway activation.

CONCLUSIONS

Collectively, these findings highlight the potential of G. frondosa as a novel therapeutic agent for AD treatment and prevention.

A conversation on allergy: recognizing the past and looking to the future

Allergy is an ever-evolving group of disorders, which includes asthma, atopic dermatitis, rhinitis and food allergies and that currently affects over 1 billion people worldwide. This group of disorders has exploded in incidence since around the start of the 20th century, implying that genetics is not solely responsible for its development but that environmental factors have an important role. Here, Fabio Luciani and Jonathan Coquet, in their role as editors at Immunology & Cell Biology, asked nine prominent researchers in the field of allergy to define the term 'allergy', discuss the role of genetics and the environment, nominate the most important discoveries of the past decade and describe the best strategies to combat allergy at the population level going forward.

The Skin Barrier and Moisturization: Function, Disruption, and Mechanisms of Repair

BACKGROUND

The anatomic layers of the skin are well-defined, and a functional model of the skin barrier has recently been described. Barrier disruption plays a key role in several skin conditions, and moisturization is recommended as an initial treatment in conditions such as atopic dermatitis. This review aimed to analyze the skin barrier in the context of the function model, with a focus on the mechanisms by which moisturizers support each of the functional layers of the skin barrier to promote homeostasis and repair.

SUMMARY

The skin barrier is comprised of four interdependent layers - physical, chemical, microbiologic, and immunologic - which maintain barrier structure and function. Moisturizers target disruption affecting each of these four layers through several mechanisms and were shown to improve transepidermal water loss in several studies. Occlusives, humectants, and emollients occlude the surface of the stratum corneum (SC), draw water from the dermis into the epidermis, and assimilate into the SC, respectively, in order to strengthen the physical skin barrier. Acidic moisturizers bolster the chemical skin barrier by supporting optimal enzymatic function, increasing ceramide production, and facilitating ideal conditions for commensal microorganisms. Regular moisturization may strengthen the immunologic skin barrier by reducing permeability and subsequent allergen penetration and sensitization.

KEY MESSAGES

The physical, chemical, microbiologic, and immunologic layers of the skin barrier are each uniquely impacted in states of skin barrier disruption. Moisturizers target each of the layers of the skin barrier to maintain homeostasis and facilitate repair.

Are Antimicrobial Peptides a 21st-Century Solution for Atopic Dermatitis?

Atopic dermatitis (AD) is a chronic inflammatory skin disorder that is the result of various environmental, bacterial and genetic stimuli, which culminate in the disruption of the skin's barrier function. Characterized by highly pruritic skin lesions, xerosis and an array of comorbidities among which skin infections are the most common, this condition results in both a significant loss of quality of life and in the need for life-long treatments (e.g., corticosteroids, monoclonal antibodies and regular antibiotic intake), all of which may have harmful secondary effects. This, in conjunction with AD's rising prevalence, made the development of alternative treatment strategies the focus of both the scientific community and the pharmaceutical industry. Given their potential to both manage the skin microbiome, fight infections and even modulate the local immune response, the use of antimicrobial peptides (AMPs) from more diverse origins has become one of the most promising alternative solutions for AD management, with some being already used with some success towards this end. However, their production and use also exhibit some limitations. The current work seeks to compile the available information and provide a better understanding of the state of the art in the understanding of AMPs' true potential in addressing AD.

Two Phase 3 Trials of Lebrikizumab for Moderate-to-Severe Atopic Dermatitis

BACKGROUND

Lebrikizumab, a high-affinity IgG4 monoclonal antibody targeting interleukin-13, prevents the formation of the interleukin-4Rα-interleukin-13Rα1 heterodimer receptor signaling complex.

METHODS

We conducted two identically designed, 52-week, randomized, double-blind, placebo-controlled, phase 3 trials; both trials included a 16-week induction period and a 36-week maintenance period. Eligible patients with moderate-to-severe atopic dermatitis (adults [≥18 years of age] and adolescents [12 to <18 years of age, weighing ≥40 kg]) were randomly assigned in a 2:1 ratio to receive either lebrikizumab at a dose of 250 mg (loading dose of 500 mg at baseline and week 2) or placebo, administered subcutaneously every 2 weeks. Outcomes for the induction period were assessed up to 16 weeks and are included in this report. The primary outcome was an Investigator's Global Assessment (IGA) score of 0 or 1 (indicating clear or almost clear skin; range, 0 to 4 [severe disease]) with a reduction (indicating improvement) of at least 2 points from baseline at week 16. Secondary outcomes included a 75% improvement in the Eczema Area and Severity Index score (EASI-75 response) and assessments of itch and of itch interference with sleep. Safety was also assessed.

RESULTS

In trial 1, the primary outcome was met in 43.1% of 283 patients in the lebrikizumab group and in 12.7% of 141 patients in the placebo group (P<0.001); an EASI-75 response occurred in 58.8% and 16.2%, respectively (P<0.001). In trial 2, the primary outcome was met in 33.2% of 281 patients in the lebrikizumab group and in 10.8% of 146 patients in the placebo group (P<0.001); an EASI-75 response occurred in 52.1% and 18.1%, respectively (P<0.001). Measures of itch and itch interference with sleep indicated improvement with lebrikizumab therapy. The incidence of conjunctivitis was higher among patients who received lebrikizumab than among those who received placebo. Most adverse events during the induction period were mild or moderate in severity and did not lead to trial discontinuation.

CONCLUSIONS

In the induction period of two phase 3 trials, 16 weeks of treatment with lebrikizumab was effective in adolescents and adults with moderate-to-severe atopic dermatitis. (Funded by Dermira; ADvocate1 and ADvocate2 ClinicalTrials.gov numbers, NCT04146363 and NCT04178967, respectively.).

mRNAs in skin surface lipids unveiled atopic dermatitis at 1 month

BACKGROUND

The molecular pathogenesis of atopic dermatitis (AD), presenting skin barrier dysfunction and abnormal inflammations around 1-2 months, is unreported.

OBJECTIVE

We aimed to examine the molecular pathogenesis of very early-onset AD by skin surface lipid-RNA (SSL-RNA) using a non-invasive technology in infants aged 1 and 2 months from a prospective cohort.

METHODS

We collected sebum by oil-blotting film of infants aged 1 and 2 months and analysed RNAs in their sebum. We diagnosed AD according to the United Kingdom Working Party's criteria.

RESULTS

Infants with AD aged 1 month showed lower expression of genes related to various lipid metabolism and synthesis, antimicrobial peptides, tight junctions, desmosomes and keratinization. They also had higher expression of several genes involved in Th2-, Th17- and Th22-type immune responses and lower expression of negative regulators of inflammation. In addition, gene expressions related to innate immunity were higher in AD infants. Infants aged 1 month with neonatal acne and diagnosed with AD aged 2 months already had gene expression patterns similar to AD aged 1 month in terms of redox, lipid synthesis, metabolism and barrier-related gene expression.

CONCLUSION

We identified molecular changes in barrier function and inflammatory markers that characterize the pathophysiology of AD in infants aged 1 month. We also revealed that neonatal acne at 1 month could predict the subsequent development of AD by sebum transcriptome data.

Allergic Contact Dermatitis and Patch Testing in Skin of Color Patients

Objective: Skin of color patients face important health issues relevant to dermatologists, such as allergic contact dermatitis; however, there is a lack of information surrounding common allergens causing contact dermatitis that disproportionately affect skin of color patients, as well as interpreting patch testing in this population. Methods: Covidence, Embase, MEDLINE, PubMed, Web of Science, and Google Scholar were searched to identify relevant articles studying allergic and irritant contact dermatitis in skin of color patients. Results: The most common positive reactions in African American patients included PPD, balsam of Peru, bacitracin, fragrance mix, and nickel. The most common positive reactions in Hispanic patients included Carba mix, nickel sulfate, and thiuram mix. The most common positive reactions in Asian patients included nickel sulfate, fragrance mix, and potassium dichromate. When interpreting patch test results in patients with higher Fitzpatrick skin types, positive patch tests presented with lichenification and hyperpigmentation, rather than erythema and vesicles. Furthermore, characteristic bright red or pink hues for positive results may appear violaceous or faint pink. Conclusions: Awareness of the common allergens associated with allergic contact dermatitis in patients of skin of color can help guide patch testing as an important diagnostic tool. Further research must be conducted regarding contact dermatitis in this patient population, especially given the relative lack of data surrounding Hispanic, Asian and Pacific Islander, and Native American patients.

Human Induced Pluripotent Stem Cell-Derived Keratinocyte-Like Cells for Research on Protease-Activated Receptor 2 in Nonhistaminergic Cascades of Atopic Dermatitis

Keratinocytes are the most abundant cells in the epidermis, and as part of the frontline immunologic defense system, keratinocytes function as a barrier to exogenous attacks. Protease-activated receptor 2 (PAR2) is expressed in human keratinocytes and activated in several inflammatory conditions, such as atopic dermatitis (AD). In this study, we demonstrated the differentiation of human induced pluripotent stem cell into keratinocytes by the improved, robust differentiation procedure and confirmed that human induced pluripotent stem cell-derived keratinocyte-like cells (iKera) express PAR2, which is activated by external addition of the ligand peptide and trypsin. The activation of PAR2 led to the release of calcium from intracellular calcium storage, followed by the release of the proinflammatory cytokine tumor necrosis factor α Moreover, PAR2 antagonist I-191 (CAS No. 1690172-25-8) inhibited calcium release in a dose-dependent manner. This is the first study to demonstrate that iKera expresses a functional PAR2 protein. Furthermore, our results indicate crosstalk between the PAR2- and IL-4-mediated inflammatory axes in iKera, suggesting that iKera can be used as a platform for a broad range of mechanism-targeted drug screening in AD. SIGNIFICANCE STATEMENT: This is the first study to provide evidence that human induced pluripotent stem cell-derived keratinocyte-like cells (iKera) express functional protease-activated receptor 2 (PAR2). Furthermore, this study demonstrated in iKera that the IL-4 inflammatory axis can crosstalk with the PAR2-mediated inflammatory axis in keratinocytes. To the best of our knowledge, this is the first report to indicate that iKera can be used for research and as a drug screening platform for atopic dermatitis.

Periostin activates distinct modules of inflammation and itching downstream of the type 2 inflammation pathway

Atopic dermatitis (AD) is a chronic relapsing skin disease accompanied by recurrent itching. Although type 2 inflammation is dominant in allergic skin inflammation, it is not fully understood how non-type 2 inflammation co-exists with type 2 inflammation or how type 2 inflammation causes itching. We have recently established the FADS mouse, a mouse model of AD. In FADS mice, either genetic disruption or pharmacological inhibition of periostin, a downstream molecule of type 2 inflammation, inhibits NF-κB activation in keratinocytes, leading to downregulating eczema, epidermal hyperplasia, and infiltration of neutrophils, without regulating the enhanced type 2 inflammation. Moreover, inhibition of periostin blocks spontaneous firing of superficial dorsal horn neurons followed by a decrease in scratching behaviors due to itching. Taken together, periostin links NF-κB-mediated inflammation with type 2 inflammation and promotes itching in allergic skin inflammation, suggesting that periostin is a promising therapeutic target for AD.

Apigenin: A Therapeutic Agent for Treatment of Skin Inflammatory Diseases and Cancer

The skin is the main barrier between the body and the environment, protecting it from external oxidative stress induced by ultraviolet rays. It also prevents the entrance of infectious agents such as viruses, external antigens, allergens, and bacteria into our bodies. An overreaction to these agents causes severe skin diseases, including atopic dermatitis, pruritus, psoriasis, skin cancer, and vitiligo. Members of the flavonoid family include apigenin, quercetin, luteolin, and kaempferol. Of these, apigenin has been used as a dietary supplement due to its various biological activities and has been shown to reduce skin inflammation by downregulating various inflammatory markers and molecular targets. In this review, we deal with current knowledge about inflammatory reactions in the skin and the molecular mechanisms by which apigenin reduces skin inflammation.

Allergic diseases in children in the age of the COVID-19 pandemic

COVID-19 coronavirus infection caused by the SARS-CoV-2 virus has become a real disaster for all of humanity. Today, issues related to diagnostics, clinical presentations, treatment of the complications, preventive measures, including vaccination for a new coronavirus infection, are relevant. It is also important to identify risk factors for a severe course of the disease, features of the development of infection against the background of comorbid conditions and different immunological reactivity of the human body. The comorbidity of allergic and infectious diseases is based on the common humoral and cellular mechanisms of the immune response. The trigger for the development of allergic diseases is often the viruses of measles and chickenpox, influenza, parainfluenza, rhinoviruses, enteroviruses, respiratory syncytial viruses, coronaviruses, and others. Most allergic patients are predisposed to acute respiratory viral infections. COVID-19 occurs in 0.39–12.3% of children. Children tend to have milder disease than adults and have low mortality rates. At the same time, one should not forget about the adequate support for patients with chronic diseases, especially children with allergic diseases. Viruses and preventive hygiene measures associated with a pandemic are triggers of an exacerbation of bronchial asthma and atopic dermatitis. Early diagnosis, adequate treatment of allergic diseases in children, and provision of doctors with information are also problematic. It is important to understand which patients with bronchial asthma are at particular risk and how inhaled glucocorticosteroids may influence the course and outcome of COVID-19. International associations and societies have developed guidelines for the management of children with allergies during the COVID-19 pandemic. Inhaled glucocorticosteroids for bronchial asthma reduce the expression of genes of the main target receptors for the SARS-CoV-2 virus. Anti-inflammatory therapy for asthma, primarily inhaled glucocorticosteroids, should be continued until asthma control is achieved, which will help reduce the risk of an unfavorable course of COVID-19.

Lactobacillus for the treatment and prevention of atopic dermatitis: Clinical and experimental evidence

Atopic dermatitis (AD) is a chronic inflammatory skin disease, accompanied by itching and swelling. The main pathological mechanism of AD is related to the imbalance between Type 2 helper cells (Th2 cells) and Type 1 helper cells (Th1 cells). Currently, no safe and effective means to treat and prevent AD are available; moreover, some treatments have side effects. Probiotics, such as some strains of Lactobacillus, can address these concerns via various pathways: i) facilitating high patient compliance; ii) regulating Th1/Th2 balance, increasing IL-10 secretion, and reducing inflammatory cytokines; iii) accelerating the maturation of the immune system, maintaining intestinal homeostasis, and improving gut microbiota; and iv) improving the symptoms of AD. This review describes the treatment and prevention of AD using 13 species of Lactobacillus. AD is commonly observed in children. Therefore, the review includes a higher proportion of studies on AD in children and fewer in adolescents and adults. However, there are also some strains that do not improve the symptoms of AD and even worsen allergies in children. In addition, a subset of the genus Lactobacillus that can prevent and relieve AD has been identified in vitro. Therefore, future studies should include more in vivo studies and randomized controlled clinical trials. Given the advantages and disadvantages mentioned above, further research in this area is urgently required.

Morus alba fruits attenuates atopic dermatitis symptoms and pathology in vivo and in vitro via the regulation of barrier function, immune response and pruritus

BACKGROUND

Morus alba fruits (MAF) belong to the Moraceae family, which are known to be effective in treating diabetic, autoimmune, and hormonal diseases owing to its low toxicity. MAF, as excerpted from Donguibogam, a representative Korean medical encyclopedia protected by UNESCO, has been widely used to treat lumbago, arthritis, and diabetes. Based on these effects, MAF is investigated for unidentified effects of atopic dermatitis, characterized by complex etiology of skin barrier dysfunction, inflammation, and chronic pruritus.

METHODS

The antioxidant, inflammatory, and immunomodulatory properties of MAF and its bioactive compounds have been widely reported. According to an examination of 1-chloro-2,4-dinitrobenzene-induced AD-like skin lesions in NC/Nga mice, AD symptoms, such as increased dermatitis score, scratching frequency, immunoglobulin E, trans-epidermal water loss, epidermal thickness, and infiltration of mast cells, were relieved by topical MAF administration. They effectively attenuated cytokines and chemokines, such as interleukin (IL)-4, IL-5, IL-6, IL-8, IL-13, IL-17A, IL-22, IL-1β, tumor necrosis factor-α, thymic stromal lymphopoietin (TSLP), thymic- and activation-regulated chemokine, normal T cell expression, and macrophage-derived chemokine secretion at the mRNA level in TNF-α/IFN-γ induced HaCaT (human immortalized keratinocyte) cells.

RESULTS

Both in vivo and in vitro models, MAF increased the expression of filaggrin, involucrin, and loricrin, as well as inhibited the activation of Janus kinase 2, signal transducer and activator of transcription proteins 1, and mitogen-activated protein kinase pathways, including extracellular signal-regulated kinase, c-jun N-terminal kinase, and p38. Moreover, MAF reduced the expression of TSLP and periostin, which play important roles in skin pruritus as chronic pruritogenic factors.

CONCLUSION

These data indicate that MAF could be used as a potential treatment for AD-like skin lesions by regulating the inflammatory response, improving physical skin barriers, and relieving symptomatic pruritus.

Early Itch Response with Abrocitinib Is Associated with Later Efficacy Outcomes in Patients with Moderate-to-Severe Atopic Dermatitis: Subgroup Analysis of the Randomized Phase III JADE COMPARE Trial

BACKGROUND

Abrocitinib, an oral Janus kinase 1 inhibitor, provided significant itch relief by week 2 in patients with moderate-to-severe atopic dermatitis (AD) in the phase III JADE COMPARE trial.

OBJECTIVES

This post-hoc analysis of JADE COMPARE aimed to further characterize itch response and determined whether early itch relief could predict subsequent improvements in AD severity.

METHODS

JADE COMPARE was a randomized, double-blind, double-dummy, placebo-controlled trial. Adult patients (aged ≥ 18 years) with moderate-to-severe AD were randomly assigned to receive oral abrocitinib 200 mg or 100 mg once daily, subcutaneous dupilumab 300 mg every other week (after a 600-mg loading dose), or placebo, plus medicated topical therapy for 16 weeks. Assessments were ≥ 4-point improvement in Peak Pruritus Numerical Rating Scale (PP-NRS4) from days 2 to 15, Eczema Area and Severity Index (EASI), Investigator's Global Assessment (IGA) response, and Dermatology Life Quality Index (DLQI) scores at week 12. Association between week 2 PP-NRS4 and efficacy at week 12 was evaluated by chi-squared tests. The predictive value of early response for later efficacy was assessed by area under the receiver operating characteristic curve.

RESULTS

As early as day 4 after treatment, a significantly greater proportion of patients achieved PP-NRS4 response with abrocitinib 200 mg (18.6%) versus dupilumab (5.6%; p < 0.001) and placebo (6.0%; p < 0.003). A similar trend was observed with abrocitinib at the 100-mg dose, with significantly greater PP-NRS4 response rates versus placebo as early as day 9. With both doses of abrocitinib, week 12 IGA 0/1, EASI-75, EASI-90, and DLQI 0/1 response rates were greater in week 2 PP-NRS4 responders than nonresponders; no differences were observed between week 2 PP-NRS4 responders and nonresponders in the dupilumab and placebo groups. Early improvement in PP-NRS at week 2 was associated with skin clearance at week 12 in abrocitinib-treated patients.

CONCLUSIONS

Abrocitinib resulted in rapid relief from itch in patients with moderate-to-severe AD, with significant improvement in itch as early as day 4 after treatment with abrocitinib 200 mg compared with dupilumab and placebo. Abrocitinib-induced itch relief by week 2 was associated with subsequent improvements at week 12. [Video abstract available.] TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03720470. Early itch response with abrocitinib is associated with later efficacy outcomes in patients withmoderate-to-severe atopic dermatitis: subgroup analysis of the randomized phase III JADE COMPARE trial (MP4 335,375kb).

JAK-STAT signaling pathway in the pathogenesis of atopic dermatitis: An updated review

Atopic dermatitis (AD) is a chronic, inflammatory, pruritic form of dermatosis with heterogeneous manifestations that can substantially affect patients' quality of life. AD has a complex pathogenesis, making treatment challenging for dermatologists. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway plays a central role in modulating multiple immune axes involved in the immunopathogenesis of AD. In particular, Th2 cytokines, including interleukin (IL)-4, IL-5, IL-13, IL-31, and thymic stromal lymphopoietin, which contribute to the symptoms of chronic inflammation and pruritus in AD, are mediated by JAK-STAT signal transduction. Furthermore, JAK-STAT is involved in the regulation of the epidermal barrier and the modulation of peripheral nerves related to the transduction of pruritus. Targeting the JAK-STAT pathway may attenuate these signals and show clinical efficacy through the suppression of various immune pathways associated with AD. Topical and oral JAK inhibitors with variable selectivity have emerged as promising therapeutic options for AD. Notably, topical ruxolitinib, oral upadacitinib, and oral abrocitinib were approved by the U.S. Food and Drug Administration for treating patients with AD. Accordingly, the present study reviewed the role of JAK-STAT pathways in the pathogenesis of AD and explored updated applications of JAK inhibitors in treating AD.

Novel Pullulan/Gellan Gum Bilayer Film as a Vehicle for Silibinin-Loaded Nanocapsules in the Topical Treatment of Atopic Dermatitis

In this study a novel gellan gum/pullulan bilayer film containing silibinin-loaded nanocapsules was developed for topical treatment of atopic dermatitis (AD). The bilayer films were produced by applying a pullulan layer on a gellan gum layer incorporated with silibinin nanocapsules by two-step solvent casting method. The bilayer formation was confirmed by microscopic analysis. In vitro studies showed that pullulan imparts bioadhesitvity for the films and the presence of nanocapsules increased their occlusion factor almost 2-fold. Besides, the nano-based film presented a slow silibinin release and high affinity for cutaneous tissue. Moreover, this film presented high scavenger capacity and non-hemolytic property. In the in vivo study, interestingly, the treatments with vehicle film attenuated the scratching behavior and the ear edema in mice induced by 2,4-dinitrochlorobenzene (DNCB). However, the nano-based film containing silibinin modulated the inflammatory and oxidative parameters in a similar or more pronounced way than silibinin solution and vehicle film, as well as than hydrocortisone, a classical treatment of AD. In conclusion, these data suggest that itself gellan gum/pullulan bilayer film might attenuate the effects induced by DNCB, acting together with silibinin-loaded nanocapsules, which protected the skin from oxidative damage, improving the therapeutic effect in this AD-model.

A Systematic Review of Atopic Dermatitis: The Intriguing Journey Starting from Physiopathology to Treatment, from Laboratory Bench to Bedside

Atopic dermatitis (AD) is a common chronic inflammatory and immune-mediated skin disease with a complex pathophysiology and still represents a therapeutic challenge, owing to limited responses to available treatments. However, recent advances in the understanding of AD pathophysiology have led to the discovery of several new potential therapeutic targets, and research in the field of new molecules with therapeutic perspectives is boiling, with more than 70 new promising drugs in development. The aim of this systematic review is to provide the state of the art on the current knowledge concerning the pathophysiology of the disease and on novel agents currently being investigated for AD, and to highlight which type of evolution is going to take place in therapeutic approaches of atopic dermatitis in the coming years.

Calcium-Based Antimicrobial Peptide Compounds Attenuate DNFB-Induced Atopic Dermatitis-Like Skin Lesions via Th-Cells in BALB/c Mice

Atopic dermatitis (AD) is a chronic and recurrent inflammatory skin disease, characterized by severe itching and recurrent skin lesions. We hypothesized that a novel treatment involving calcium-based antimicrobial peptide compounds (CAPCS), a combination of natural calcium extracted from marine shellfish, and a variety of antimicrobial peptides, may be beneficial for AD. We established a dinitrofluorobenzene (DNFB)-induced AD model in BALB/c mice to test our hypothesis. We observed mouse behavior and conducted histopathological and immunohistochemical analyses on skin lesions before and after CAPCS treatment. We also characterized the changes in the levels of cytokines, inflammatory mediators, and Toll-like receptors (TLRs) in plasma and skin lesions. The results showed that (i) topical application of CAPCS ameliorated AD-like skin lesions and reduced scratching behavior in BALB/c mice; (ii) CAPCS suppressed infiltration of inflammatory cells and inhibited the expression of inflammatory cytokines in AD-like skin lesions; (iii) CAPCS reduced plasma levels of inflammatory cytokines; and (iv) CAPCS inhibited TLR2 and TLR4 protein expression in skin lesions. Topical application of CAPCS exhibits a therapeutic effect on AD by inhibiting inflammatory immune responses via recruiting helper T cells and engaging the TLR2 and TLR4 signaling pathways. Therefore, CAPCS may be useful for the treatment of AD.

Management of Atopic Dermatitis: The Role of Tacrolimus

Atopic dermatitis (AD) is a long-lasting inflammatory dermatological condition characterized by itchy, eczematous, sparsely tiny blisters that hold a clear watery substance. Additionally, the diseased skin can suppurate, occasionally with weeping with thickening of the affected skin. This is considered one of the top skin disorders involving both children and adult populations globally. The principal therapeutic intervention for AD is long-standing topical glucocorticoids, which have been used for several decades. Corticosteroid therapy brings several adverse drug effects (ADRs), including irreversible skin atrophy. Tacrolimus belongs to the class of calcineurin inhibitors, which is a type of immunomodulator possessing promising efficacy in treating AD. Topical tacrolimus is an effective and safe non-corticosteroid substitute treatment for AD. We reviewed the available literature to compare and institute the safety, efficacy, and effectiveness of tacrolimus when equated to corticosteroid therapy in managing AD.

Equine keratinocytes in the pathogenesis of insect bite hypersensitivity: Just another brick in the wall?

Equine insect bite hypersensitivity (IBH) is the most common skin disease affecting horses. It is described as an IgE-mediated, Type I hypersensitivity reaction to salivary gland proteins of Culicoides insects. Together with Th2 cells, epithelial barrier cells play an important role in development of Type I hypersensitivities. In order to elucidate the role of equine keratinocytes in development of IBH, we stimulated keratinocytes derived from IBH-affected (IBH-KER) (n = 9) and healthy horses (H-KER) (n = 9) with Culicoides recombinant allergens and extract, allergic cytokine milieu (ACM) and a Toll like receptor ligand 1/2 (TLR-1/2-L) and investigated their transcriptomes. Stimulation of keratinocytes with Culicoides allergens did not induce transcriptional changes. However, when stimulated with allergic cytokine milieu, their gene expression significantly changed. We found upregulation of genes encoding for CCL5, -11, -20, -27 and interleukins such as IL31. We also found a strong downregulation of genes such as SCEL and KRT16 involved in the formation of epithelial barrier. Following stimulation with TLR-1/2-L, keratinocytes significantly upregulated expression of genes affecting Toll like receptor and NOD-receptor signaling pathway as well as NF-kappa B signaling pathway, among others. The transcriptomes of IBH-KER and H-KER were very similar: without stimulations they only differed in one gene (CTSL); following stimulation with allergic cytokine milieu we found only 23 differentially expressed genes (e.g. CXCL10 and 11) and following stimulation with TLR-1/2-L they only differed by expression of seven genes. Our data suggests that keratinocytes contribute to the innate immune response and are able to elicit responses to different stimuli, possibly playing a role in the pathogenesis of IBH.

Barrier function of the skin and the role of fat-soluble vitamins in the correction of its disorders

The main function of the skin is to protect the body from negative environmental influences. The physical barrier permeability is mainly represented by the stratum corneum; however, other layers of the epidermis and the dermis are its important components. The mechanical strength of the skin is provided by intercellular contacts in the epidermis and structural proteins of the dermis. The chemical-biological barrier includes lipids, acids, natural moisturizing factor and antimicrobial peptides. Mucosal immunity system creates a barrier against infection. The microflora of healthy skin counteracts its colonization by pathogens and is vital for its immune functions. Physiological processes in the skin are closely related. A violation in one of them often leads to the formation of a whole cascade of pathological reactions affecting all the links of its protection. Vitamins A, D and E are used to correct impaired barrier function of the skin. The most pronounced effect of vitamin A (retinol palmitate) is the proliferation of epidermal cells and synthesis of extracellular matrix structures of the dermis; vitamin D (cholecalciferol) regulation of differentiation and suppression of excessive proliferation of keratinocytes; vitamin E (tocopherol acetate) antioxidant effect. The combined use of these vitamins in the composition of RadevitActive ointment affects all the main elements of the protection of the epidermis and dermis: strengthens the mechanical strength of the stratum corneum and dermis, stabilizes chemical and physical protection, including prevents the penetration of foreign substances and microorganisms, reduces transepidermal loss of water and electrolytes, reduces the damaging effect of UV, increases antimicrobial and antioxidant protection.

Potential Natural Biomolecules Targeting JAK/STAT/SOCS Signaling in the Management of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by the dysregulation of cytokines and other immune mediators. JAK/STAT is a classical signal transduction pathway involved in various biological processes, and its dysregulation contributes to the key aspects of AD pathogenesis. Suppressor of cytokine signaling (SOCS) proteins negatively regulate the immune-related inflammatory responses mediated by the JAK/STAT pathway. JAK/STAT-mediated production of cytokines including IL-4, IL-13, IL-31, and TSLP inhibits the expression of important skin barrier proteins and triggers pruritus in AD. The expression of SOCS proteins regulates the JAK-mediated cytokines and facilitates maintaining the skin barrier disruptions seen in AD. STATs are crucial in dendritic-cell-activated Th2 cell differentiation in the skin, releasing inflammatory cytokines, indicating that AD is a Th2-mediated skin disorder. SOCS proteins aid in balancing Th1/Th2 cells and, moreover, regulate the onset and maintenance of Th2-mediated allergic responses by reducing the Th2 cell activation and differentiation. SOCS proteins play a pivotal role in inflammatory cytokine-signaling events that act via the JAK/STAT pathway. Therapies relying on natural products and derived biomolecules have proven beneficial in AD when compared with the synthetic regimen. In this review, we focused on the available literature on the potential natural-product-derived biomolecules targeting JAK/STAT/SOCS signaling, mainly emphasizing the SOCS family of proteins (SOCS1, SOCS3, and SOCS5) acting as negative regulators in modulating JAK/STAT-mediated responses in AD pathogenesis and other inflammatory disorders.

Efficacy and Safety of Mucopolysaccharide Polysulfate Cream for Non-Exudative Eczema: A Systematic Review and Meta-Analysis

Background: Mucopolysaccharide polysulfate (MPS) cream as a moisturizer is widely applied to treat eczema, and a lot of clinical trials have demonstrated its efficacy and safety. However, there is no further research to collect and analyze these studies.

Objective: This meta-analysis aimed to assess the efficacy and safety of MPS cream as monotherapy or add-on therapy for non-exudative eczema.

Methods: Ten databases were searched to identify the eligible randomized controlled trials (RCTs) from their inception to July 31, 2021. Revman 5.3 software was used for the meta-analysis.

Results: A total of eligible 20 studies were included. Among the 20 studies, 2 studies compared MPS cream with other moisturizers, 14 compared MPS cream plus topical corticosteroids (TCS) with TCS alone, and 4 compared with MPS cream plus tacrolimus ointment with tacrolimus ointment alone. The pooled results demonstrated that MPS cream had a higher total efficacy rate [Risk ratio (RR) 1.21, 95% CI: 1.12 to 1.30, P < 0.00001], a lower recurrence rate (RR 0.44, 95% CI: 0.26 to 0.74, P = 0.002) and a lower pruritus score [mean difference (MD) −1.78, 95% CI: −2.16 to −1.40, P < 0.00001] than urea cream or vaseline ointment. Moreover, in comparison with TCS or tacrolimus ointment alone, the combination treatment performed better in terms of total efficacy rate, total symptom score, recurrence rate, and pruritus score. For safety, the skin adverse events were mild, and MPS cream as monotherapy or add-on therapy did not increase the risk of skin adverse events.

Conclusions: MPS cream as monotherapy or add-on therapy could provide a good effect for treating non-exudative eczema with mild and tolerable skin adverse events. However, due to the suboptimal quality of the included studies, high-quality and large-sample RCTs are needed in the future for update or validation.

Systematic Review Registration: PROSPERO (https://www.crd.york.ac.uk/PROSPERO/), identifier: CRD42021265735.

[The use of magnetic therapy in the treatment and medical rehabilitation of atopic dermatitis in children and adolescents]

An urgent aspect of scientific research in atopic dermatitis is the development of new complex methods of pathogenetic and symptomatic therapy and alternative treatment options that can effectively relieve exacerbations of the disease and prolong remission between them. As a therapeutic physical factor, magnetotherapy has long been successfully used in medical practice. Promising medical technologies include transcranial application of a traveling variable magnetic field, local low-frequency magnetotherapy, and magnetophoresis. The main tasks of rehabilitation and treatment are aimed at normalizing the state of all organs, the central and autonomic nervous system of the patient, reducing hypersensitivity and itching of atopic skin, as well as normalizing sleep and relieving psycho-emotional stress.

Gut-derived short-chain fatty acids modulate skin barrier integrity by promoting keratinocyte metabolism and differentiation

Barrier integrity is central to the maintenance of healthy immunological homeostasis. Impaired skin barrier function is linked with enhanced allergen sensitization and the development of diseases such as atopic dermatitis (AD), which can precede the development of other allergic disorders, for example, food allergies and asthma. Epidemiological evidence indicates that children suffering from allergies have lower levels of dietary fibre-derived short-chain fatty acids (SCFA). Using an experimental model of AD-like skin inflammation, we report that a fermentable fibre-rich diet alleviates systemic allergen sensitization and disease severity. The gut-skin axis underpins this phenomenon through SCFA production, particularly butyrate, which strengthens skin barrier function by altering mitochondrial metabolism of epidermal keratinocytes and the production of key structural components. Our results demonstrate that dietary fibre and SCFA improve epidermal barrier integrity, ultimately limiting early allergen sensitization and disease development.The Graphical Abstract was designed using Servier Medical Art images ( https://smart.servier.com ).

Recent Developments and Advances in Atopic Dermatitis: A Focus on Epidemiology, Pathophysiology, and Treatment in the Pediatric Setting

Atopic dermatitis (AD) is a chronic inflammatory skin disorder that affects a substantial number of children and has a significant negative impact on affected patients and their caregivers/families. Recent studies have led to significant evolutions in the understanding of AD pathogenesis, epidemiology, and treatment. The first point of contact for many patients with new-onset AD is usually with their primary care provider or pediatrician. This underscores the importance for pediatricians to understand the basic pathophysiology and current standards of care for AD. This article provides up-to-date information and reviews the basic principles of AD pathophysiology, diagnosis, and management. In addition, the article highlights recent advances in scientific research regarding the mechanisms involved in the pathogenesis of atopic dermatitis that have resulted in the discovery of novel therapeutic targets and the development of targeted biologic therapies with the potential to revolutionize AD therapy.

An updated review on efficacy and benefits of sweet almond, evening primrose and jojoba oils in skin care applications

Renewed consumer and industry interest in natural ingredients has led to a large growth of natural cosmetics. This has put pressure on formulation skills and product claims when it comes to using natural compounds. Taking a strategic and comprehensive approach in viewing natural ingredients, including natural oils, as 'active' ingredients rather than just providing for so-called 'natural' claims, aids both innovation and development. Given the ever-increasing consumer demand for natural ingredients, and more importantly the demand for effective natural ingredients including plant oils, it is important for the cosmetic industry to re-evaluate them in this context. The objectives of this review are to provide an update of three popular cosmetic plant oils - Sweet Almond, Evening Primrose, and Jojoba - in terms of their cosmetic applications as 'active' ingredients. This review highlights the activity of these oils, in the management of dry skin, ageing skin, juvenile skin, atopic dermatitis, scalp conditions, and their wider potential. Attention is given to formulation considerations where the content of these oils impacts product oxidation, skin penetration and stratum corneum homeostasis. Benefits of these oils have been well documented both pre-clinically and clinically. Historically, they have been used for hundreds if not thousands of years for their management and treatment of various skin and other ailments. Given the discrepancies in some clinical data presented for a variety of dermatoses, the importance of the choice of oil and how to formulate with them within the context of the epidermal barrier function, skin penetration, and toxicity, cannot be underestimated. Care should be taken in terms of the quality and stability of theses oils, as well as ensuring best formulation type, if the reported activities of these oils are to be achieved with consistency. Despite discrepancies in the literature and questionable study designs, it is clear, that Sweet Almond, Evening Primrose and Jojoba oils, do have skin care benefits for both adult and juvenile applications. They are effective ingredients for skin care preparations to strengthen stratum corneum integrity, recovery, and lipid ratio. Nevertheless, further experimental data are required concerning the impact on stratum corneum physiology and structure.

Barrier Impairment and Type 2 Inflammation in Allergic Diseases: The Pediatric Perspective

Allergic diseases represent a global burden. Although the patho-physiological mechanisms are still poorly understood, epithelial barrier dysfunction and Th2 inflammatory response play a pivotal role. Barrier dysfunction, characterized by a loss of differentiation, reduced junctional integrity, and altered innate defence, underpins the pathogenesis of allergic diseases. Epithelial barrier impairment may be a potential therapeutic target for new treatment strategies Up now, monoclonal antibodies and new molecules targeting specific pathways of the immune response have been developed, and others are under investigation, both for adult and paediatric populations, which are affected by atopic dermatitis (AD), asthma, allergic rhinitis (AR), chronic rhinosinusitis with nasal polyps (CRSwNP), or eosinophilic esophagitis (EoE). In children affected by severe asthma biologics targeting IgE, IL-5 and against IL-4 and IL-13 receptors are already available, and they have also been applied in CRSwNP. In severe AD Dupilumab, a biologic which inhibits both IL-4 and IL-13, the most important cytokines involved in inflammation response, has been approved for treatment of patients over 12 years. While a biological approach has already shown great efficacy on the treatment of severe atopic conditions, early intervention to restore epithelial barrier integrity, and function may prevent the inflammatory response and the development of the atopic march.

Pathological functions of granzyme B in inflammatory skin diseases

Dysregulated skin immunity is a hallmark of many skin diseases such as atopic dermatitis, autoimmune blistering diseases, and interface dermatitis. Current treatment options for the inflammatory skin diseases are limited and sometimes ineffective, therefore further understanding of pathomechanisms in the inflammatory skin conditions is necessary to develop new therapeutic alternatives. Recent studies suggest that the serine protease, granzyme B, is a key mediator in multiple inflammatory skin diseases, implying that strategies targeting granzyme B may be an attractive treatment option for such diseases. Specifically, granzyme B exhibits not only an intracellular apoptotic function but also extracellular proteolytic roles in inflammatory skin diseases including infectious diseases, pemphigoid diseases, atopic dermatitis, alopecia areata, and interface dermatitis. In this review, we summarize the current understanding with respect to the functions of granzyme B in the pathomechanism of various inflammatory skin diseases and evaluate the possibility of therapeutics targeting granzyme B.

The F11 Receptor (F11R)/Junctional Adhesion Molecule-A (JAM-A) (F11R/JAM-A) in cancer progression

The F11 Receptor (F11R), also called Junctional Adhesion Molecule-A (JAM-A) (F11R/JAM-A), is a transmembrane glycoprotein of the immunoglobulin superfamily, which is mainly located in epithelial and endothelial cell tight junctions and also expressed on circulating platelets and leukocytes. It participates in the regulation of various biological processes, as diverse as paracellular permeability, tight junction formation and maintenance, leukocyte transendothelial migration, epithelial-to-mesenchymal transition, angiogenesis, reovirus binding, and platelet activation. Dysregulation of F11R/JAM-A may result in pathological consequences and disorders in normal cell function. A growing body of evidence points to its role in carcinogenesis and invasiveness, but its tissue-specific pro- or anti-tumorigenic role remains a debated issue. The following review focuses on the F11R/JAM-A tissue-dependent manner in tumorigenesis and metastasis and also discusses the correlation between poor patient clinical outcomes and its aberrant expression. In the future, it will be required to clarify the signaling pathways that are activated or suppressed via the F11R/JAM-A protein in various cancer types to understand its multiple roles in cancer progression and further use it as a novel direct target for cancer treatment.

Atopic dermatitis: an expanding therapeutic pipeline for a complex disease

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with a complex pathophysiology that underlies a wide spectrum of clinical phenotypes. AD remains challenging to treat owing to the limited response to available therapies. However, recent advances in understanding of disease mechanisms have led to the discovery of novel potential therapeutic targets and drug candidates. In addition to regulatory approval for the IL-4Ra inhibitor dupilumab, the anti-IL-13 inhibitor tralokinumab and the JAK1/2 inhibitor baricitinib in Europe, there are now more than 70 new compounds in development. This Review assesses the various strategies and novel agents currently being investigated for AD and highlights the potential for a precision medicine approach to enable prevention and more effective long-term control of this complex disease.

Recent advances in understanding of the complex phenotype and mechanisms underlying atopic dermatitis (AD) have revealed multiple new potential targets for pharmacological intervention. Here, Bieber reviews therapeutic strategies and assesses the expanding pipeline for the therapy of AD, highlighting the potential for a precision medicine approach to the management of this complex disorder.

Thymic stromal lymphopoietin induces adipose loss through sebum hypersecretion

Emerging studies indicate that the immune system can regulate systemic metabolism. Here, we show that thymic stromal lymphopoietin (TSLP) stimulates T cells to induce selective white adipose loss, which protects against obesity, improves glucose metabolism, and mitigates nonalcoholic steatohepatitis. Unexpectedly, adipose loss was not caused by alterations in food intake, absorption, or energy expenditure. Rather, it was induced by the excessive loss of lipids through the skin as sebum. TSLP and T cells regulated sebum release and sebum-associated antimicrobial peptide expression in the steady state. In human skin, TSLP expression correlated directly with sebum-associated gene expression. Thus, we establish a paradigm in which adipose loss can be achieved by means of sebum hypersecretion and uncover a role for adaptive immunity in skin barrier function through sebum secretion.

The precision of macroscale mechanical measurements is limited by the inherent structural heterogeneity of human stratum corneum

Biological tissues are structurally heterogenous mosaics at cellular and sub-cellular length scales. Some tissues, like the outermost layer of human skin, or stratum corneum (SC), also exhibit a rich topography of microchannels at larger mesoscopic length scales. Although this is well understood, modern studies continue to characterize the mechanical properties of biological tissues, including the SC, using macroscale techniques that assume these materials are homogenous in structure, thickness, and composition. Macroscale failure testing of SC is commonly associated with large sample to sample variability. We anticipate that microscale heterogeneities play an important role in defining the global mechanical response of the tissue. To evaluate the validity of the prevailing paradigm that macroscopic testing techniques can provide meaningful information about failure in soft heterogenous tissues, the macroscale work of fracture in isolated human SC samples is measured using conventional macroscale testing techniques and compared with the energy cost of creating new crack interfaces at the microscale, measured using a modified traction force microscopy technique. Results show that measured micro- and macroscale energy costs per unit crack path length are highly consistent. However, crack propagation is found to be guided by microscale topographical features in the tissue. This correlation reveals that macroscale mechanical sample to sample variability is caused by notable differences in crack propagation pathways. STATEMENT OF SIGNIFICANCE: Although designed to test homogeneous materials, macroscopic uniaxial tensometry is currently the gold standard for measuring the mechanical properties of biological tissues. All tissues, including human stratum corneum are structurally heterogeneous at the microscale and mechanical measurements are commonly highly variable, even for specimens from the same source. This study explores the fundamental causes of this disparity and evaluates the prevailing paradigm that macroscopic testing techniques can provide meaningful information about failure in soft heterogeneous tissues. Results conclude that the cause of large variability in mechanical work of fracture is due to inherent structural heterogeneities governing crack propagation pathways and altering the total crack length. Structural heterogeneities in tissue therefore limits the precision of macroscale biomechanical testing.

The IL-4, IL-13 and IL-31 pathways in atopic dermatitis

Introduction: Atopic dermatitis (AD) is the most common inflammatory skin disease. It has a complex pathophysiology, with a combination of immune dysregulation and intrinsic barrier defects driving cutaneous inflammation and allergic symptomatology. The IL-4, IL-13 and IL-31 inflammatory pathways have been identified as hallmark features in the pathogenesis of the disease, contributing uniquely and synergistically to immune and barrier abnormalities as well as the key symptoms, such as pruritis. Novel therapeutics that target these pathways have been under development to find treatments for AD.Areas covered: This review discusses the IL-4, IL-13 and IL-31 pathways in AD. We will also detail novel targeted therapeutics that have recently been or are currently in clinical trials for AD. A literature search was conducted by querying Scopus, Google Scholar, PubMed, and Clinicaltrials.gov up to January 2021 using combinations of the search terms 'IL-4' 'IL-13' 'IL-31' 'atopic dermatitis' 'immune pathway' 'biologics' 'novel therapeutics' 'JAK/STAT inhibitors.'Expert opinion: The complex pathophysiology of AD advocates for innovation. Novel minimally invasive sampling modalities such as tape stripping will allow for a broader characterization of the immunomechanisms behind AD pathophysiology. This will allow for the continued development of a personalized medicine approach to treat AD.

Cera Flava Alleviates Atopic Dermatitis by Activating Skin Barrier Function via Immune Regulation

Cera Flava (CF), a natural extract obtained from beehives, is widely used in dermatological products owing to its wound healing, wrinkle reduction, UV-protective, and skin cell turnover stimulation effects. However, its effect on AD-like skin lesions is unknown. In this study, we used a mouse model of AD to evaluate the effects of CP at the molecular and phenotypic levels. Topical house dust mite (HDM) sensitization and challenge were performed on the dorsal skin of NC/Nga mice to induce AD-like cutaneous lesions, phenotypes, and immunologic responses. The topical application of CF for 6 weeks relieved HDM-induced AD-like phenotypes, as quantified by the dermatitis severity score, scratching frequency, and skin moisture. CP decreased immunoglobulin E, histamine, and thymic stromal lymphopoietin levels. Histopathological analysis showed that CF decreased epidermal thickening and the number of mast cells. CF attenuated HDM-induced changes in the expression of skin barrier-related proteins. Furthermore, CF decreased the mRNA levels of inflammatory factors, including interleukin (IL)-1β, IL-4, IL-13, IL-8, TARC, MDC, and RANTES, in dorsal skin tissue via the TLR2/MyD88/TRAF6/ERK pathway. CF influences skin barrier function and immune regulation to alleviate AD symptoms. It may therefore be an effective alternative to topical steroids for the treatment of AD.

Pharmacokinetics of Ruxolitinib in Patients with Atopic Dermatitis Treated With Ruxolitinib Cream: Data from Phase II and III Studies

BACKGROUND

Pathogenesis of atopic dermatitis (AD) involves the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. A cream formulation of ruxolitinib, a potent selective JAK1/JAK2 inhibitor, was developed for topical delivery.

METHOD

Pharmacokinetic data were obtained from three double-blind, vehicle-controlled studies in patients with AD: a phase II study with ruxolitinib cream 0.15%, 0.5%, or 1.5% once daily or 1.5% twice daily (BID), and two phase III studies with 0.75% or 1.5% BID. Effects of baseline characteristics on pharmacokinetics were examined. Correlations were attempted between plasma concentrations and change in hematological parameters over time.

RESULTS

Ruxolitinib plasma concentrations at steady-state (Css) increased with cream strength in a less-than-dose-proportional manner. In the phase III studies, overall mean (standard deviation [SD]) Css after ruxolitinib cream 0.75% and 1.5% BID (23.8 [35.0] and 35.7 [55.0] nM) were a fraction of the half-maximal inhibitory concentration for thrombopoietin-stimulated phosphorylated STAT3 inhibition (281 nM), a JAK/STAT signaling marker. Three covariates were identified for Css: dose, percent body surface area (%BSA) treated, and baseline Investigator's Global Assessment score. Mean (SD) bioavailability of ruxolitinib cream 1.5% BID was 6.22% (7.66%). There were no correlations between Css and any hematological changes except for a transient increase in platelets at week 2.

CONCLUSIONS

Plasma ruxolitinib concentrations after treatment with topical ruxolitinib cream in patients with up to 20% BSA affected by AD are not expected to lead to systemic plasma concentrations that may be associated with adverse effects commonly associated with oral JAK inhibitors. CLINICALTRIALS.GOV: NCT03011892; NCT03745638; NCT03745651.

Linearized esculentin-2EM shows pH dependent antibacterial activity with an alkaline optimum

Here the hypothesis that linearized esculentin 2EM (E2EM-lin) from Glandirana emeljanovi possesses pH dependent activity is investigated. The peptide showed weak activity against Gram-negative bacteria (MLCs ≥ 75.0 μM) but potent efficacy towards Gram-positive bacteria (MLCs ≤ 6.25 μM). E2EM-lin adopted an α-helical structure in the presence of bacterial membranes that increased as pH was increased from 6 to 8 (↑ 15.5-26.9%), whilst similar increases in pH enhanced the ability of the peptide to penetrate (↑ 2.3-5.1 mN m^-1) and lyse (↑ 15.1-32.5%) these membranes. Theoretical analysis predicted that this membranolytic mechanism involved a tilted segment, that increased along the α-helical long axis of E2EM-lin (1-23) in the N → C direction, with -  < µH > increasing overall from circa - 0.8 to - 0.3. In combination, these data showed that E2EM-lin killed bacteria via novel mechanisms that were enhanced by alkaline conditions and involved the formation of tilted and membranolytic, α-helical structure. The preference of E2EM-lin for Gram-positive bacteria over Gram-negative organisms was primarily driven by the superior ability of phosphatidylglycerol to induce α-helical structure in the peptide as compared to phosphatidylethanolamine. These data were used to generate a novel pore-forming model for the membranolytic activity of E2EM-lin, which would appear to be the first, major reported instance of pH dependent AMPs with alkaline optima using tilted structure to drive a pore-forming process. It is proposed that E2EM-lin has the potential for development to serve purposes ranging from therapeutic usage, such as chronic wound disinfection, to food preservation by killing food spoilage organisms.

The pruritogenic role of the type 2 immune response in diseases associated with chronic itch

While there is a vast array of aetiologies that may lead to chronic pruritus, recent data suggests that many of these conditions share similar interactions between keratinocytes, nerves, and the immune system. Specifically, the type 2 immune response, including Th2 T Cells and their related cytokines, has been noted to play a major role in the development of pruritus in a variety of itchy conditions. To date, atopic dermatitis is the most striking example of this pathogenesis. However, the body of literature supporting its role in many other itchy conditions, including other inflammatory, bullous, as well as systemic diseases, continues to grow. In addition, new treatments targeting this type 2 immune system continue to be developed and investigated. In the current review, we present the current body of literature supporting the role of the type 2 immune response in itchy conditions beyond atopic dermatitis as well as potential therapeutic options that target this pathway for chronic itch.

Systems Pharmacology and In Silico Docking Analysis Uncover Association of CA2, PPARG, RXRA, and VDR with the Mechanisms Underlying the Shi Zhen Tea Formula Effect on Eczema

Eczema is a complex chronic inflammatory skin disease impacted by environmental factors, infections, immune disorders, and deficiencies in skin barrier function. Shi Zhen Tea (SZT), derived from traditional Chinese medicine Xiao-Feng-San, has shown to be an effective integrative therapy for treating skin lesions, itching, and sleeping loss, and it facilitates reduction of topical steroid and antihistamine use in pediatric and adult patients with severe eczema. Yet, its active compounds and therapeutic mechanisms have not been elucidated. In this study, we sought to investigate the active compounds and molecular mechanisms of SZT in treating eczema using systems pharmacology and in silico docking analysis. SZT is composed of 4 medicinal herbs, Baizhu (Atractylodis macrocephalae rhizome), Jingjie (Schizonepetae herba), Kushen (Sophorae flavescentis radix), and Niubangzi (Arctii fructus). We first identified 51 active compounds from SZT and their 81 potential molecular targets by high-throughput computational analysis, from which we identified 4 major pathways including Th17 cell differentiation, metabolic pathways, pathways in cancer, and the PI3K-Akt signaling pathway. Through network analysis of the compound-target pathway, we identified hub molecular targets within these pathways including carbonic anhydrase II (CA2), peroxisome proliferator activated receptor γ (PPAR γ), retinoid X receptor α (RXRA), and vitamin D receptor (VDR). We further identified top 5 compounds including cynarine, stigmasterin, kushenol, β-sitosterol, and (24S)-24-propylcholesta-5-ene-3β-ol as putative key active compounds on the basis of their molecular docking scores with identified hub target proteins. Our study provides an insight into the therapeutic mechanism underlying multiscale benefits of SZT for eczema and paves the way for developing new and potentially more effective eczema therapies.