A Narrative Review of the IL-18 and IL-37 Implications in the Pathogenesis of Atopic Dermatitis and Psoriasis: Prospective Treatment Targets.

Atopic dermatitis and psoriasis are prevalent inflammatory skin conditions that significantly impact the quality of life of patients, with diverse treatment options available. Despite advances in understanding their underlying mechanisms, recent research highlights the significance of interleukins IL-18 and IL-37, in Th1, Th2, and Th17 inflammatory responses, closely associated with the pathogenesis of psoriasis and atopic dermatitis. Hence, IL-18 and IL-37 could potentially become therapeutic targets. This narrative review synthesizes knowledge on these interleukins, their roles in atopic dermatitis and psoriasis, and emerging treatment strategies. Findings of a literature search up to 30 May 2024, underscore a research gap in IL-37-targeted therapies. Conversely, IL-18-focused treatments have demonstrated promise in adult-onset Still's Disease, warranting further exploration for their potential efficacy in psoriasis and atopic dermatitis.

[Modification of allergic dermatitis on the associations between early-life exposure to size-specific particulate matter and childhood allergic rhinitis].

To evaluate the modification of allergic dermatitis on the association between PM exposure and allergic rhinitis in preschool children. This cross-sectional study was based on a questionnaire conducted between June 2019 and June 2020 to caregivers of children aged 3 to 6 years in the kindergartens of 7 Chinese cities to collect information on allergic rhinitis and allergic dermatitis. A mature machine learning-based space-time extremely randomized trees model was applied to estimate early-life, prenatal, and first-year exposure of PM1, PM2.5 and PM10 at 1 km×1 km resolution. A combination of multilevel logistic regression and restricted cubic spline functions was used to quantitatively assess whether allergic dermatitis modifies the associations between size-specific PM exposure and the risk of childhood allergic rhinitis. The results showed that out of 28 408 children, 14 803 (52.1%) were boys and 13 605 (47.9%) were girls; the age of children ranged from 3.1 to 6.8 years, with a mean age of (4.9±0.9) years, of which 3 586 (12.6%) were diagnosed with allergic rhinitis. Among all children, 17 832 (62.8%) were breastfed for more than 6 months and 769 (2.7%) had parental history of atopy. A total of 21 548 children (75.9%) had a mother with an educational level of university or above and 7 338 (29.6%) had passive household cigarette smoke exposure. The adjusted ORs for childhood allergic rhinitis among the children with allergic dermatitis as per interquartile range (IQR) increase in early-life PM1(9.8 µg/m3), PM2.5 (14.9 µg/m3) and PM10 (37.7 µg/m3) were significantly higher than the corresponding ORs among the children without allergic dermatitis [OR: 1.45, 95%CI (1.26, 1.66) vs. 1.33, 95%CI (1.20, 1.47), for PM1; OR: 1.38, 95%CI (1.23, 1.56) vs. 1.32, 95%CI (1.21, 1.45), for PM2.5; OR: 1.56, 95%CI (1.31, 1.86) vs. 1.46, 95%CI (1.28, 1.67), for PM10]. The interactions between allergic dermatitis and size-specific PM exposure on childhood allergic rhinitis were statistically significant (Z value=19.4, all P for interaction<0.001). The similar patterns were observed for both prenatal and first-year size-specific PM exposure and the results of the dose-response relationship were consistent with those of the logistic regression. In conclusion, allergic dermatitis, as an important part of the allergic disease progression, may modify the association between ambient PM exposure and the risk of childhood allergic rhinitis. Children with allergic dermatitis should pay more attention to minimize outdoor air pollutants exposure to prevent the further progression of allergic diseases.

Interplay between diabetes mellitus and atopic dermatitis.

Inflammatory dermatoses such as atopic dermatitis (AD) have long been linked to the pathogenesis of diabetes mellitus. Indeed, numerous studies show an increased risk of diabetes mellitus in individuals with AD although lower prevalence of diabetes mellitus is also observed in few studies. Though the underlying mechanisms accounting for the reciprocal influence between these two conditions are still unclear, the complex interplay between diabetes mellitus and AD is attributable, in part, to genetic and environmental factors, cytokines, epidermal dysfunction, as well as drugs used for the treatment of AD. Proper management of one condition can mitigate the other condition. In this review, we summarize the evidence of the interaction between diabetes mellitus and AD, and discuss the possible underlying mechanisms by which these two conditions influence each other.

Type-2 immunity associated with type-1 related skin inflammatory diseases: friend or foe?

Chronic inflammatory skin diseases are multifactorial diseases that combine genetic predisposition, environmental triggers, and metabolic disturbances associated with abnormal immune responses. From an immunological perspective, the better understanding of their physiopathology has demonstrated a large complex network of immune cell subsets and related cytokines that interact with both epidermal and dermal cells. For example, in type-1-associated diseases such as alopecia areata, vitiligo, and localized scleroderma, recent evidence suggests the presence of a type-2 inflammation that is well known in atopic dermatitis. Whether this type-2 immune response has a protective or detrimental impact on the development and chronicity of these diseases remains to be fully elucidated, highlighting the need to better understand its involvement for the management of patients. This mini-review explores recent insights regarding the potential role of type-2-related immunity in alopecia areata, vitiligo, and localized scleroderma.

Association between exposure to ambient air pollution, meteorological factors and atopic dermatitis consultations in Singapore-a stratified nationwide time-series analysis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease affecting approximately 20% of children globally. While studies have been conducted elsewhere, air pollution and weather variability is not well studied in the tropics. This time-series study examines the association between air pollution and meteorological factors with the incidence of outpatient visits for AD obtained from the National Skin Centre (NSC) in Singapore. The total number of 1,440,844 consultation visits from the NSC from 2009 to 2019 was analysed. Using the distributed lag non-linear model and assuming a negative binomial distribution, the short-term temporal association between outpatient visits for AD and air quality and meteorological variability on a weekly time-scale were examined, while adjusting for long-term trends, seasonality and autocorrelation. The analysis was also stratified by gender and age to assess potential effect modification. The risk of AD consultation visits was 14% lower (RR10th percentile: 0.86, 95% CI 0.78-0.96) at the 10th percentile (11.9 µg/m3) of PM2.5 and 10% higher (RR90th percentile: 1.10, 95% CI 1.01-1.19) at the 90th percentile (24.4 µg/m3) compared to the median value (16.1 µg/m3). Similar results were observed for PM10 with lower risk at the 10th percentile and higher risk at the 90th percentile (RR10th percentile: 0.86, 95% CI 0.78-0.95, RR90th percentile: 1.10, 95% CI 1.01-1.19). For rainfall for values above the median, the risk of consultation visits was higher up to 7.4 mm in the PM2.5 model (RR74th percentile: 1.07, 95% CI 1.00-1.14) and up to 9 mm in the PM10 model (RR80th percentile: 1.12, 95% CI 1.00-1.25). This study found a close association between outpatient visits for AD with ambient particulate matter concentrations and rainfall. Seasonal variations in particulate matter and rainfall may be used to alert healthcare providers on the anticipated rise in AD cases and to time preventive measures to reduce the associated health burden.

Atopic Dermatitis Disease Complications.

This chapter will describe infectious complications of atopic dermatitis, including bacterial, viral, and fungal infections and the evolving understanding of the relationship between atopic dermatitis and infectious disease. The underlying immunological dysregulation and poor skin barrier function associated with atopic dermatitis not only increase the likelihood of infectious complications but also lend atopic dermatitis skin vulnerable to flares induced by environmental triggers. Thus, this chapter will also highlight the impact of common external environmental agents on precipitating flares of disease. Lastly, this chapter will discuss complications that can arise from treatments and the association of atopic dermatitis with more serious conditions such as lymphoma.

The role of the environment in allergic skin disease.

PURPOSE OF REVIEW: This paper explores how environmental factors influence allergic skin diseases, including atopic dermatitis (AD), contact dermatitis (CD), urticaria, angioedema, and reactions to drugs and insect bites. RECENT FINDINGS: Research indicates a significant impact of environmental elements on allergic skin diseases. High air pollution levels exacerbate symptoms, while climate change contributes to increased skin barrier dysfunction, particularly affecting AD. Allergen prevalence is influenced by climate and pollution. Irritants, like those in detergents and cosmetics, play a major role in CD. Plants also contribute, causing various skin reactions. Understanding the interplay between environmental factors and allergic skin diseases is crucial for effective management. Physicians must address these factors to support patient well-being and promote skin health amidst environmental changes.

Atopic Dermatitis in Children.

Atopic dermatitis (AD) is extremely common in the pediatric population, and most children with AD will first present to their primary care provider (PCP). The PCP can recognize AD by its clinical features, including itch, a chronic relapsing course, and the characteristic eruption. The cornerstone of AD therapy is dry skin care, typically a short daily bath/shower followed by an emollient applied to all skin. Most children with AD will also require topical medications, such as topical corticosteroids and/or topical nonsteroidal therapies. For children with more severe disease, systemic agents, including several novel therapies, may be required. In managing AD, the clinician must monitor for side effects of medications as well as complications of the AD itself, the most common of which is secondary infection. An understanding of the pathogenesis, treatments, and complications of AD is essential for the PCP, as untreated (or undertreated) AD has a significant impact on the quality of life of affected children and their caregivers. [Pediatr Ann. 2024;53(4):e121-e128.].

Integrated Omics Analysis Uncovers the Culprit behind Exacerbated Atopic Dermatitis in a Diet-Induced Obesity Model.

Atopic dermatitis (AD), a chronic inflammatory skin disease, is exacerbated by obesity, yet the precise linking mechanism remains elusive. This study aimed to elucidate how obesity amplifies AD symptoms. We studied skin samples from three mouse groups: sham control, AD, and high-fat (HF) + AD. The HF + AD mice exhibited more severe AD symptoms than the AD or sham control mice. Skin lipidome analysis revealed noteworthy changes in arachidonic acid (AA) metabolism, including increased expression of pla2g4, a key enzyme in AA generation. Genes for phospholipid transport (Scarb1) and acyltransferase utilizing AA as the acyl donor (Agpat3) were upregulated in HF + AD skin. Associations were observed between AA-containing phospholipids and skin lipids containing AA and its metabolites. Furthermore, imbalanced phospholipid metabolism was identified in the HF + AD mice, marked by excessive activation of the AA and phosphatidic acid (PA)-mediated pathway. This imbalance featured increased expression of Plcb1, Plcg1, and Dgk involved in PA generation, along with a decrease in genes converting PA into diglycerol (DG) and CDP-DG (Lpin1 and cds1). This investigation revealed imbalanced phospholipid metabolism in the skin of HF + AD mice, contributing to the heightened inflammatory response observed in HF + AD, shedding light on potential mechanisms linking obesity to the exacerbation of AD symptoms.

Investigation of the relationship between atopic dermatitis of dogs and intestinal epithelial damage.

BACKGROUND: A significant association between atopic dermatitis and leaky gut syndrome has been demonstrated in humans. No studies have been conducted to determine whether there is an association between atopic dermatitis and intestinal damage in dogs. OBJECTIVES: This study aimed to determine whether there is an association between canine atopic dermatitis and intestinal damage using selected intestinal-related biomarkers. METHODS: Twenty-six dogs with atopic dermatitis and 10 healthy dogs were included. Moderate-to-severe pruritus, erythema, erosion and alopecia on different parts of the body were sought in dogs to suspect atopic dermatitis. The presence of atopic dermatitis was confirmed by an allergic skin test. Serum biomarkers including intestinal fatty acid binding protein (I-FABP), intestinal alkaline phosphatase (IAP), trefoil factor-3 (TFF-3), immunoglobulin E (IgE), interleukin-4 (IL-4) and interleukin-13 (IL-13) concentrations were measured from venous blood samples. RESULTS: Of the 26 dogs tested for allergens, 16 were found to be sensitive to mould mites, 10 to vernal grass, eight to house dust mites, five to wheat dust and five to grass pollen mix allergens. Significant increases in serum IAP, TFF-3, IgE, IL-4 and IL-13 concentrations were determined. CONCLUSION: It was thought that the increase in TFF-3 and IAP concentrations may be due to the presence of intestinal epithelial damage and the repair of this damage. In addition, the development of atopic dermatitis may be predisposed to the entry of allergens into the body through sites of intestinal damage.

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

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

The Role of Inhalant Allergens on the Clinical Manifestations of Atopic Dermatitis.

BACKGROUND: Inhalant allergens provide a source of environmental factors that contribute to the development of clinical symptoms in patients with atopic dermatitis (AD). OBJECTIVE: To review the relationship between inhalant allergens and AD. METHODS: A literature review was conducted using three databases: PubMed/MEDLINE, ClinicalKey, and Web of Science. Search terms, including "atopic dermatitis," "atopic eczema," and "eczema," were used in combination with "inhalant allergen," "inhaled allergen," and "aeroallergen" to identify relevant published manuscripts that highlight the relationship between AD and exposures to inhalant allergens. RESULTS: Fifteen articles were suitable for review. The studies included in the review investigated the effect of inhalant allergens on the clinical manifestations of AD through bronchial provocation, direct skin contact, and allergen sensitization. CONCLUSION: There is a significant relationship between exposures to inhalant allergens and AD. Inhalant allergens may aggravate AD symptoms by either bronchial provocation or direct skin contact. Sensitization of inhalant allergens, mainly house dust mites, follows a specific age-related pattern.

Maternal dietary indexes are not linked to early childhood wheezing or atopic eczema.

BACKGROUND: Several recent studies have investigated the association between maternal diet during pregnancy and wheezing or asthma in children. However, whether a specific dietary pattern during pregnancy protects children from wheezing or atopic diseases remains unclear. This study investigated the association between The Alternative Healthy Eating Index for Pregnancy (AHEI-P), the Dietary Inflammatory Index (DII), and the risk for wheezing and atopic eczema in children during the first year of life. METHODS: This study included 1330 mother-child pairs who attended the Kuopio Birth Cohort (KuBiCo) study and had dietary information during the last trimester and information on children's health in the first year of life. AHEI-P and DII indicate a healthy diet and dietary inflammation potential during pregnancy. The AHEI-P and DII were compared with reported wheezing and doctor-diagnosed atopic eczema in children during the first year of life. RESULTS: Neither AHEI-P nor DII is associated with wheezing or atopic eczema in children when analyzed by continuous variables and by tertiles. The odds ratio (95% CI) for AHEI-P and wheezing was 0.99 (0.98-1.01), for AHEI-P and atopic eczema1.01 (0.99-1.02), for DII and wheezing 1.02 (0.95-1.09), and for DII and atopic eczema 0.97 (0.91-1.04). CONCLUSION: In this cohort study, AHEI-P and DII during pregnancy were not associated with wheezing or atopic eczema in the offspring during the first year of life.

Unraveling the skin; a comprehensive review of atopic dermatitis, current understanding, and approaches.

Atopic dermatitis, also known as atopic eczema, is a chronic inflammatory skin disease characterized by red pruritic skin lesions, xerosis, ichthyosis, and skin pain. Among the social impacts of atopic dermatitis are difficulties and detachment in relationships and social stigmatization. Additionally, atopic dermatitis is known to cause sleep disturbance, anxiety, hyperactivity, and depression. Although the pathological process behind atopic dermatitis is not fully known, it appears to be a combination of epidermal barrier dysfunction and immune dysregulation. Skin is the largest organ of the human body which acts as a mechanical barrier to toxins and UV light and a natural barrier against water loss. Both functions face significant challenges due to atopic dermatitis. The list of factors that can potentially trigger or contribute to atopic dermatitis is extensive, ranging from genetic factors, family history, dietary choices, immune triggers, and environmental factors. Consequently, prevention, early clinical diagnosis, and effective treatment may be the only resolutions to combat this burdensome disease. Ensuring safe and targeted drug delivery to the skin layers, without reaching the systemic circulation is a promising option raised by nano-delivery systems in dermatology. In this review, we explored the current understanding and approaches of atopic dermatitis and outlined a range of the most recent therapeutics and dosage forms brought by nanotechnology. This review was conducted using PubMed, Google Scholar, and ScienceDirect databases.

Association between Outdoor and Indoor Air Pollution Sources and Atopic Eczema among Preschool Children in South Africa.

The objective of the study was to investigate the association between outdoor and indoor air pollution sources and atopic eczema among preschool children in South Africa. A cross-sectional design, following the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III protocol, was applied. The study was conducted in Mabopane and Soshanguve Townships in the City of Tshwane Metropolitan Municipality in Gauteng, South Africa. A total population of 1844 preschool children aged 7 years and below participated in the study; 1840 were included in the final data analysis. Data were analyzed using multilevel logistic regression analysis. The prevalence of eczema ever (EE) and current eczema symptoms (ESs) was 11.9% and 13.3%, respectively. The use of open fires (paraffin, wood, or coal) for cooking and heating increased the likelihood of EE (OR = 1.63; 95% CI: 0.76-3.52) and current ESs (OR = 1.94; 95% CI: 1.00-3.74). Environmental tobacco smoke (ETS) exposure at home increased the likelihood of EE (OR = 1.66; 95% CI: 1.08-2.55) and current ESs (OR = 1.61; 95% CI: 1.07-2.43). Mothers or female guardians smoking cigarettes increased the likelihood of EE (OR = 1.50; 95% CI: 0.86-2.62) and current ESs (OR = 1.23; 95% CI: 0.71-2.13). The use of combined building materials in homes increased the likelihood of EE, and corrugated iron significantly increased the likelihood of current ESs. The frequency of trucks passing near the preschool children's residences on weekdays was found to be associated with EE and current ESs, with a significant association observed when trucks passed the children's residences almost all day on weekdays. Atopic eczema was positively associated with exposure to outdoor and indoor air pollution sources.

Atopic Dermatitis in Early Childhood and Risk of Inflammatory Bowel Disease: A Scandinavian Birth Cohort Study.

OBJECTIVE: To examine the association between early-life atopic manifestations and later risk of inflammatory bowel disease (IBD), for which prospective data are scarce. STUDY DESIGN: The population-based All Babies in Southeast Sweden (ABIS) and Norwegian Mother, Father, and Child (MoBa) cohorts follow children from birth (ABIS 1997-1999; MoBa 2000-2009) to the end of 2021. Based on validated questionnaires, parents prospectively reported information on asthma, food-related allergic symptoms, atopic dermatitis, and allergic rhinitis by age 3. IBD was defined by ≥ 2 diagnostic records in the national health registries. Cox regression estimated hazard ratios adjusted (aHRs) for parental IBD, atopy, education level, smoking habits, and national origin. Cohort-specific estimates were pooled using a random-effects model. RESULTS: We compiled data on 83 311 children (ABIS, n = 9041; MoBa, n = 74 270). In over 1 174 756 person-years of follow-up, 301 participants were diagnosed with IBD. Children with atopic dermatitis at age 3 had an increased risk of IBD (pooled aHR = 1.46 [95% CI = 1.13-1.88]), Crohn's disease (pooled aHR = 1.53 [95%CI = 1.04-2.26]), and ulcerative colitis (pooled aHR = 1.78 [95%CI = 1.15-2.75]). Conversely, any atopic manifestation by age 3 was not associated with IBD (pooled aHR = 1.20 [95%CI = 0.95-1.52]), nor were analyses specifically focused on early-life food-related allergic symptoms, asthma, and allergic rhinitis. CONCLUSION: While atopic manifestations in early childhood were overall not associated with IBD, children with atopic dermatitis specifically were at increased risk of developing IBD, suggesting shared etiologic traits; these findings might be useful in identifying at-risk individuals for IBD.

Short-chain fatty acids (SCFA) in infants' plasma and corresponding mother's milk and plasma in relation to subsequent sensitisation and atopic disease.

BACKGROUND: Short-chain fatty acids (SCFAs) in intestinal contents may influence immune function, while less is known about SCFAs in blood plasma. The aims were to investigate the relation between infants' and maternal plasma SCFAs, as well as SCFAs in mother's milk, and relate SCFA concentrations in infant plasma to subsequent sensitisation and atopic disease. METHODS: Infant plasma (N = 148) and corresponding mother's milk and plasma were collected four months postpartum. Nine SCFA (formic, acetic, propionic, isobutyric, butyric, succinic, valeric, isovaleric, and caproic acid) were analysed by UPLC-MS. At 12 months of age, atopic disease was diagnosed by a pediatric allergologist, and sensitisation was measured by skin prick test. All families participated in the Swedish birth cohort NICE (Nutritional impact on Immunological maturation during Childhood in relation to the Environment). FINDINGS: Infants with sensitisation, atopic eczema, or food allergy had significantly lower concentrations of five, three, and two SCFAs, respectively, in plasma at four months. Logistic regressions models showed significant negative associations between formic, succinic, and caproic acid and sensitisation [ORadj (95% CI) per SD: 0.41 (0.19-0.91); 0.19 (0.05-0.75); 0.25 (0.09-0.66)], and between acetic acid and atopic eczema [0.42 (0.18-0.95)], after adjusting for maternal allergy. Infants' and maternal plasma SCFA concentrations correlated strongly, while milk SCFA concentrations were unrelated to both. Butyric and caproic acid concentrations were enriched around 100-fold, and iso-butyric and valeric acid around 3-5-fold in mother's milk, while other SCFAs were less prevalent in milk than in plasma. INTERPRETATION: Butyric and caproic acid might be actively transported into breast milk to meet the needs of the infant, although mechanistic studies are needed to confirm this. The negative associations between certain SCFAs on sensitisation and atopic disease adds to prior evidence regarding their immunoregulatory potential. FUNDING: Swedish Research Council (Nr. 2013-3145, 2019-0137 and 2023-02217 to A-S.S.), Swedish Research Council for Health, Working Life and Welfare FORTE, Nr 2018-00485 to A.W.), The Swedish Asthma and Allergy Association's Research Fund (2020-0020 to A.S.).

Dietary factors and the risk of atopic dermatitis: a Mendelian randomisation study.

Previous studies have revealed an association between dietary factors and atopic dermatitis (AD). To explore whether there was a causal relationship between diet and AD, we performed Mendelian randomisation (MR) analysis. The dataset of twenty-one dietary factors was obtained from UK Biobank. The dataset for AD was obtained from the publicly available FinnGen consortium. The main research method was the inverse-variance weighting method, which was supplemented by MR‒Egger, weighted median and weighted mode. In addition, sensitivity analysis was performed to ensure the accuracy of the results. The study revealed that beef intake (OR = 0·351; 95 % CI 0·145, 0·847; P = 0·020) and white bread intake (OR = 0·141; 95 % CI 0·030, 0·656; P = 0·012) may be protective factors against AD. There were no causal relationships between AD and any other dietary intake factors. Sensitivity analysis showed that our results were reliable, and no heterogeneity or pleiotropy was found. Therefore, we believe that beef intake may be associated with a reduced risk of AD. Although white bread was significant in the IVW analysis, there was large uncertainty in the results given the wide 95 % CI. Other factors were not associated with AD in this study.

Updates in atopic dermatitis for the primary care physician: A review of advances in the understanding and treatment of atopic dermatitis.

Atopic dermatitis (AD) is a common inflammatory skin condition occurring in both pediatric and adult patients. Pruritus is a clinical hallmark of the disease, and patients with AD often experience disruptions to their quality of life. The pathogenesis of AD is a complex and multifactorial interplay between genetic factors, epidermal barrier disruption, and immune dysregulation. Clinically, AD is characterized by pruritus, eczematous skin changes, and age-specific lesion distribution patterns. Infants and young children tend to have AD lesions on their face and extensor surfaces of their extremities while older children and adults tend to have AD lesions on flexural surfaces of their extremities. Many patients also experience a chronic and relapsing disease course. Due to the chronicity and severe pruritus, lesions often undergo secondary changes like lichenification. Patients with AD can experience a number of comorbidities including other atopic disease (i.e. allergic rhinitis, asthma), skin infections, cardiovascular, and neuropsychiatric illnesses. Management of AD depends on the severity of the disease as well as the distribution of the disease. Traditionally, treatment of AD included the use of moisturizers / emollients, topical corticosteroids or topical calcineurin inhibitors, or systemic therapy with non-selective immunosuppressants such as corticosteroids, cyclosporine, azathioprine, or similar. However, in the past decade, new biologic and small molecule drugs, both topical and systemic, have become important therapeutic options for AD patients, especially for those with moderate-to-severe disease. The development of these medications, following decades of research to better understand AD, are designed to specifically target various components of immune dysregulation and inflammation implicated in the pathogenesis of AD. Their successful development and deployment now allow for an exciting new era of treatment for individuals suffering from atopic dermatitis.

Atopic dermatitis: Pathophysiology, microbiota, and metabolome - A comprehensive review.

Atopic dermatitis (AD) is a prevalent inflammatory skin condition that commonly occurs in children. Genetics, environment, and defects in the skin barrier are only a few of the factors that influence how the disease develops. As human microbiota research has advanced, more scientific evidence has shown the critical involvement of the gut and skin bacteria in the pathogenesis of atopic dermatitis. Microbiome dysbiosis, defined by changed diversity and composition, as well as the development of pathobionts, has been identified as a potential cause for recurring episodes of atopic dermatitis. Gut dysbiosis causes "leaky gut syndrome" by disrupting the epithelial lining of the gut, which allows bacteria and other endotoxins to enter the bloodstream and cause inflammation. The same is true for the disruption of cutaneous homeostasis caused by skin dysbiosis, which enables bacteria and other pathogens to reach deeper skin layers or even systemic circulation, resulting in inflammation. Furthermore, it is now recognized that the gut and skin microbiota releases both beneficial and toxic metabolites. Here, this review covers a range of topics related to AD, including its pathophysiology, the microbiota-AD connection, commonly used treatments, and the significance of metabolomics in AD prevention, treatment, and management, recognizing its potential in providing valuable insights into the disease.