Takeshi Yoshida

Introduction: Atopic Dermatitis (AD) is a chronic inflammatory skin disease characterized by complex pathogenesis, variable clinical phenotypes, and broad severity spectrum. We utilized a serum‐proteomic approach integrated with machine learning (ML) to identify novel biomarkers that distinguish mild from severe AD. Methods: Serum from sixty‐seven AD adults, stratified by Eczema Area and Severity Index/EASI and Rajka‐Langeland/RJL into mild (≤ 7 and ≤ 4, respectively; n = 33) or severe (≥ 20 and ≥ 8, respectively; n = 34), was analyzed with Olink Explore 3072. Differentially expressed proteins (DEPs) were identified using t‐tests and False Discovery Rate correction (FDR ≤ 0.05). Tissue enrichment analysis was conducted using HPAStainR. Pearson correlations were performed between DEPs and clinical variables, serum lactate dehydrogenase/LDH and biomarkers for Th‐pathways. ML (TMLE/SuperLearner, Boruta, MUVR) was used to identify top severity biomarkers. Results: 469 DEPs distinguished severe vs. mild AD. DEPs were significantly enriched for epithelial proteins (e.g., skin, tonsil, and esophagus epithelium). Subsets correlated strongly with LDH (68 DEPs) and/or Th2/Th22 markers (90 DEPs; r ≥ 0.6, FDR ≤ 0.05). Nine serum proteins (CCL17, CCL22, DEFB4A/B, EZR, GPR15L, IL22, PRSS53, SERPINB8, SETMAR) overlapped across three ML analyses as severity discriminating biomarkers (cross‐validated AUC = 0.989; 95% CI: 0.974–1.00). Conclusions: Severe AD exhibits a proteomic footprint enriched in epithelial‐associated proteins that correlate with LDH‐associated tissue injury and/or Th2/Th22 pathways. In this cross‐sectional cohort, ML identified biomarkers that discriminated mild/severe AD groups with high cross‐validated accuracy. Longitudinal and external validation studies, including healthy controls, are needed to determine specificity, generalizability, and prognostic utility.

Studies have demonstrated that bleach baths improve atopic dermatitis (AD) severity; however, the effects on itch, skin barrier, and cutaneous microbial composition are less clear. We examined whether bleach baths reduce itch, normalize skin barrier function, reduce S. aureus absolute abundance, and increase microbial diversity in adults with AD who were colonized with S. aureus on their non-lesional skin. This was an open label, non-randomized, controlled trial performed at a single academic center. Fifteen AD and five non-atopic healthy controls (NA) were instructed to take two bleach baths (0.005% NaClO; 5–10 min duration) per week for a total of 12 weeks as add-on therapy. Adults 18 to 65 years (inclusive) with mild to severe AD were recruited with EASI score > 6.0, S. aureus culture positivity, access to a bathtub, and ability and willingness to maintain current topical or systemic treatments. They were evaluated at baseline (before bleach baths), 6 weeks, and 12 weeks after the intervention of twice-weekly bleach baths. Efficacy measurements included EASI as well as 5-D Pruritus and ItchyQoL™. Transepidermal water loss (TEWL) and stratum corneum (SC) integrity assay were performed to assess the skin barrier. Skin dysbiosis was measured by S. aureus cultivation, S. aureus abundance (qPCR of thermonuclease gene), and V1-V3 16S rRNA gene sequencing on non-lesional and lesional AD skin. After 12 weeks of bleach baths, 8/15 (53.3%) AD subjects achieved an EASI₅₀ and a significant reduction in itch as measured by 5-D pruritus and Itchy QoL. Eighty-seven percent reported improvements in sleep quality. At study entry, AD subjects had higher non-lesional TEWL values than NA subjects, and only AD subjects experienced a reduction with bleach baths (p = 0.006). Similarly, SC integrity improved as early as 6 weeks after bleach baths in AD subjects. Notably, bleach baths had no significant effect on S. aureus culture-positivity, qPCR absolute abundance, or microbial diversity. The addition of twice-weekly bleach baths improves investigator-assessed AD severity, patient-reported pruritus and sleep as well as physiological measures of skin barrier function in adult AD subjects while having no effect on qualitative and quantitative measures of cutaneous S. aureus. Trial Registration: ClinicalTrials.gov Identifier: NCT01996150, Date of registration: November 27th, 2013.

Introduction Patients with atopic dermatitis (AD) are uniquely susceptible to a number of serious viral skin complications, including eczema herpeticum (EH), caused by herpes simplex virus. This study explored the associations between biomarkers of epithelial barrier dysfunction, type 2 immunity, Staphylococcus aureus infection, and S. aureus-specific immunoglobulin responses in a cohort of AD subjects with and without a history of EH (EH+ and EH−, respectively). Methods A total of 112 subjects with AD (56 EH+, 56 EH−), matched by age and AD severity, were selected from a registry of over 3000 AD subjects. Logistic regression was used to test the association between history of S. aureus skin infection and history of EH, while controlling for a number of confounders. Results Compared to those without a history of S. aureus skin infection, subjects with a history of S. aureus skin infection were found to have more than sixfold increased odds of having a history of EH (6.60, 95% confidence interval [CI]: 2.00–21.83), after adjusting for history of other viral skin infections (molluscum contagiosum virus, human papillomavirus), serum total IgE, and IgG against the S. aureus virulence factor SElX. Conclusions These findings indicate an important relationship between S. aureus skin infections and EH.

Atopic dermatitis (AD) is the most common chronic and relapsing inflammatory skin disease. AD is typically characterized by skewed T helper (Th) 2 inflammation, yet other inflammatory profiles (Th1, Th17, Th22) have been observed in human patients. How cytokines from these different Th subsets impact barrier function in this disease is not well understood. As such, we investigated the impact of the canonical Th17 cytokine, IL-17A, on barrier function and protein composition in primary human keratinocytes and human skin explants. These studies demonstrated that IL-17A enhanced tight junction formation and function in both systems, with a dependence on STAT3 signaling. Importantly, the Th2 cytokine, IL-4 inhibited the barrier-enhancing effect of IL-17A treatment. These observations propose that IL-17A helps to restore skin barrier function, but this action is antagonized by Th2 cytokines. This suggests that restoration of IL-17/IL-4 ratio in the skin of AD patients may improve barrier function and in so doing improve disease severity.

AM‐19226 is a pathogenic, non‐O1/non‐O139 serogroup strain of Vibrio cholerae that uses a Type 3 Secretion System (T3SS) mediated mechanism to colonize host tissues and disrupt homeostasis, causing cholera. Co‐culturing the Caco2‐BBE human intestinal epithelial cell line with AM‐19226 in the presence of bile results in rapid mammalian cell death that requires a functional T3SS. We examined the role of bile, sought to identify the mechanism, and evaluated the contributions of T3SS translocated effectors in in vitro cell death. Our results suggest that Caco2‐BBE cytotoxicity does not proceed by apoptotic or necrotic mechanisms, but rather displays characteristics consistent with osmotic lysis. Cell death was preceded by disassembly of epithelial junctions and reorganization of the cortical membrane skeleton, although neither cell death nor cell‐cell disruption required VopM or VopF, two effectors known to alter actin dynamics. Using deletion strains, we identified a subset of AM‐19226 Vops that are required for host cell death, which were previously assigned roles in protein translocation and colonization, suggesting that they function other than to promote cytotoxicity. The collective results therefore suggest that cooperative Vop activities are required to achieve cytotoxicity in vitro, or alternatively, that translocon pores destabilize the membrane in a bile dependent manner.