Skin microbiome and its association with host cofactors in determining atopic dermatitis severity

Deciphering assembly processes, network complexity and stability of potential pathogenic communities in two anthropogenic coastal regions of a highly urbanized estuary

The existence of potential pathogens may lead to severe water pollution, disease transmission, and the risk of infectious diseases, posing threats to the stability of aquatic ecosystems and human health. In-depth research on the dynamic of potential pathogenic communities is of significant importance, it can provide crucial support for assessing the health status of aquatic ecosystems, maintaining ecological balance, promoting sustainable economic development, and safeguarding human health. Nevertheless, the current understanding of the distribution and geographic patterns of potential pathogens in coastal ecosystems remains rather limited. Here, we investigated the diversity, assembly, and co-occurrence network of potential pathogenic communities in two anthropogenic coastal regions, i.e., the eight mouths (EPR) and nearshore region (NSE), of the Pearl River Estuary (PRE) and a total of 11 potential pathogenic types were detected. The composition and diversity of potential pathogenic communities exhibited noteworthy distinctions between the EPR and NSE, with 6 shared potential pathogenic families. Additionally, in the NSE, a significant pattern of geographic decay was observed, whereas in the EPR, the pattern of geographic decay was not significant. Based on the Stegen null model, it was noted that undominant processes (53.36%/69.24%) and heterogeneous selection (27.35%/25.19%) dominated the assembly of potential pathogenic communities in EPR and NSE. Co-occurrence network analysis showed higher number of nodes, a lower average path length and graph diameter, as well as higher level of negative co-occurrences and modularity in EPR than those in NSE, indicating more complex and stable correlations between potential pathogens in EPR. These findings lay the groundwork for the effective management of potential pathogens, offering essential information for ecosystem conservation and public health considerations in the anthropogenic coastal regions.

Time-dependent risk of atopic dermatitis following nontyphoidal Salmonella infection

BACKGROUND

The pathogenesis of atopic dermatitis (AD) remains unclear. Nontyphoidal Salmonella (NTS) infection might trigger immune-mediated reactions. We aimed to examine NTS and the risk of subsequent AD.

METHODS

From 2002 to 2015, eligible patients (aged 0-100 years) with NTS were identified. NTS and non-NTS groups were matched at a 1:10 ratio on age and sex. We utilized conditional multivariable Cox proportional hazard models to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) for AD development. Subgroup analyses were conducted based on age, sex, and severity of NTS infection. We utilized landmark analysis to explore the time-dependent hazard of AD following NTS.

RESULTS

In the NTS group (N = 6624), 403 developed AD. After full adjustment of demographics and comorbidities, the NTS group had a higher risk of AD than the reference group (aHR = 1.217, 95% CI = 1.096-1.352). Age-stratified analysis revealed that NTS group exhibited an elevated risk compared to the reference group, particularly among those aged 13-30 years (aHR = 1.25, 95% CI = 1.017-1.559), individuals aged 31-50 years (aHR = 1.388, 95% CI = 1.112-1.733), those aged 51-70 years (aHR = 1.301, 95% CI = 1.008-1.679), and individuals aged 71 years and over (aHR = 1.791, 95% CI = 1.260-2.545). Severe NTS was associated with a higher risk of AD than the reference group (aHR = 2.411, 95% CI = 1.577-3.685). Landmark analysis showed generally consistent findings.

CONCLUSIONS

Minimizing exposure to NTS infection may represent a prospective strategy for averting the onset and progression of atopic dermatitis.

Race science without racists: how bigoted paradigms persist in allergy research

In the wake of the murder of George Floyd and the massacre in Buffalo, the editorial boards of the prominent scientific publication companies formally apologized for their journals' historical role in advancing race science and promised to improve their standards. However, flowery commentaries cannot undo the consistent pattern of endorsing biologic differences between ethnic groups, even when discussing diseases or traits that are not considered politically charged. In this report, an exemplar is made of a recent publication claiming to identify phenotypes of atopic dermatitis that are distinct between European Americans, Asians, and African Americans. The insufficiency of the evidence and logic underlying these claims are discussed. Although devoid of malice, numerous publications continue to demonstrate how claims of biological differences between races is mainstreamed in modern scientific publications. Overall, the goal of this work is to challenge the scientific community, particularly the publication companies, to evaluate how assumptions of innate biologic disadvantage have clouded assessments of racial disparities in disease beyond the topics that are more stereotypical of race science.

Exploring the skin microbiome in atopic dermatitis pathogenesis and disease modification

Inflammatory skin diseases such as atopic eczema (atopic dermatitis [AD]) affect children and adults globally. In AD, the skin barrier is impaired on multiple levels. Underlying factors include genetic, chemical, immunologic, and microbial components. Increased skin pH in AD is part of the altered microbial microenvironment that promotes overgrowth of the skin microbiome with Staphylococcus aureus. The secretion of virulence factors, such as toxins and proteases, by S aureus further aggravates the skin barrier deficiency and additionally disrupts the balance of an already skewed immune response. Skin commensal bacteria, however, can inhibit the growth and pathogenicity of S aureus through quorum sensing. Therefore, restoring a healthy skin microbiome could contribute to remission induction in AD. This review discusses direct and indirect approaches to targeting the skin microbiome through modulation of the skin pH; UV treatment; and use of prebiotics, probiotics, and postbiotics. Furthermore, exploratory techniques such as skin microbiome transplantation, ozone therapy, and phage therapy are discussed. Finally, we summarize the latest findings on disease and microbiome modification through targeted immunomodulatory systemic treatments and biologics. We believe that targeting the skin microbiome should be considered a crucial component of successful AD treatment in the future.

In Silico Elucidation of Key Drivers of Staphyloccocus aureus-Staphyloccocus epidermidis-Induced Skin Damage in Atopic Dermatitis Lesions

Staphylococcus aureus (SA) colonizes and can damage skin in atopic dermatitis lesions, despite being commonly found with Staphylococcus epidermidis (SE), a commensal that can inhibit SA's virulence and kill SA. In this study, we developed an in silico model, termed a virtual skin site, describing the dynamic interplay between SA, SE, and the skin barrier in atopic dermatitis lesions to investigate the mechanisms driving skin damage by SA and SE. We generated 106 virtual skin sites by varying model parameters to represent different skin physiologies and bacterial properties. In silico analysis revealed that virtual skin sites with no skin damage in the model were characterized by parameters representing stronger SA and SE growth attenuation than those with skin damage. This inspired an in silico treatment strategy combining SA-killing with an enhanced SA-SE growth attenuation, which was found through simulations to recover many more damaged virtual skin sites to a non-damaged state, compared with SA-killing alone. This study demonstrates that in silico modelling can help elucidate the key factors driving skin damage caused by SA-SE colonization in atopic dermatitis lesions and help propose strategies to control it, which we envision will contribute to the design of promising treatments for clinical studies.

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.

Dupilumab Alters Both the Bacterial and Fungal Skin Microbiomes of Patients with Atopic Dermatitis

The skin microbiome at lesion sites in patients with atopic dermatitis (AD) is characterized by dysbiosis. Although the administration of dupilumab, an IL-4Rα inhibitor, improves dysbiosis in the bacterial microbiome, information regarding the fungal microbiome remains limited. This study administered dupilumab to 30 patients with moderate-to-severe AD and analyzed changes in both fungal and bacterial skin microbiomes over a 12-week period. Malassezia restricta and M. globosa dominated the fungal microbiome, whereas non-Malassezia yeast species increased in abundance, leading to greater microbial diversity. A qPCR analysis revealed a decrease in Malassezia colonization following administration, with a higher reduction rate observed where the pretreatment degree of colonization was higher. A correlation was found between the group classified by the Eczema Area and Severity Index, the group categorized by the concentration of Thymus and activation-regulated chemokine, and the degree of skin colonization by Malassezia. Furthermore, an analysis of the bacterial microbiome also confirmed a decrease in the degree of skin colonization by the exacerbating factor Staphylococcus aureus and an increase in the microbial diversity of the bacterial microbiome. Our study is the first to show that dupilumab changes the community structure of the bacterial microbiome and affects the fungal microbiome in patients with AD.

Functional heterogeneity of human skin-resident memory T cells in health and disease

The human skin is populated by a diverse pool of memory T cells, which can act rapidly in response to pathogens and cancer antigens. Tissue-resident memory T cells (TRM ) have been implicated in range of allergic, autoimmune and inflammatory skin diseases. Clonal expansion of cells with TRM properties is also known to contribute to cutaneous T-cell lymphoma. Here, we review the heterogeneous phenotypes, transcriptional programs, and effector functions of skin TRM . We summarize recent studies on TRM formation, longevity, plasticity, and retrograde migration and contextualize the findings to skin TRM and their role in maintaining skin homeostasis and altered functions in skin disease.

Combining 16S Sequencing and qPCR Quantification Reveals Staphylococcus aureus Driven Bacterial Overgrowth in the Skin of Severe Atopic Dermatitis Patients

Atopic dermatitis (AD) is an inflammatory skin disease with a microbiome dysbiosis towards a high relative abundance of Staphylococcus aureus. However, information is missing on the actual bacterial load on AD skin, which may affect the cell number driven release of pathogenic factors. Here, we combined the relative abundance results obtained by next-generation sequencing (NGS, 16S V1-V3) with bacterial quantification by targeted qPCR (total bacterial load = 16S, S. aureus = nuc gene). Skin swabs were sampled cross-sectionally (n = 135 AD patients; n = 20 healthy) and longitudinally (n = 6 AD patients; n = 6 healthy). NGS and qPCR yielded highly inter-correlated S. aureus relative abundances and S. aureus cell numbers. Additionally, intra-individual differences between body sides, skin status, and consecutive timepoints were also observed. Interestingly, a significantly higher total bacterial load, in addition to higher S. aureus relative abundance and cell numbers, was observed in AD patients in both lesional and non-lesional skin, as compared to healthy controls. Moreover, in the lesional skin of AD patients, higher S. aureus cell numbers significantly correlated with the higher total bacterial load. Furthermore, significantly more severe AD patients presented with higher S. aureus cell number and total bacterial load compared to patients with mild or moderate AD. Our results indicate that severe AD patients exhibit S. aureus driven increased bacterial skin colonization. Overall, bacterial quantification gives important insights in addition to microbiome composition by sequencing.