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Background Epidermal Langerhans cells ( LC) expressing the high-affinity receptor for IgE (Fcε RI) play a key role in atopic dermatitis ( AD). AD skin is highly colonized with Staphylococcus aureus (S.a.), which are sensed by Toll-like receptor 2 ( TLR2). We hypothesized that TLR2 may impact on the expression of Fcε RI on LC. Objectives To study a putative impact of TLR2 signaling on Fcε RI, we analyzed Fcε RI and known transcription factors of the receptor after ligand binding to TLR2. Methods We generated LC from CD34+ progenitors in vitro ( CD34 LC) expressing Fcε RI and TLR2 as well as its partners TLR1 and TLR6. The expression of Fcε RI and known transcription factors of the receptor was analyzed on the protein and RNA level by flow cytometry, Western blotting, and real-time PCR. Results For CD34LC from 123 donors, we observed a high heterogeneity in FcεRI surface expression correlating with mRNA level of its α-chain. Stimulation of TLR1/2 or TLR2/6 dramatically down-regulated FcεRI on protein and mRNA level of both α- and γ-chain. Further analysis of putative transcription factors for FCER1A revealed the lack of GATA1 in CD34LC, weak expression of ELF1 and YY1, and high expression of PU.1. While ELF1 and YY1 appeared to be little affected by TLR2 engagement, PU.1 was significantly down-regulated. Conclusions Taken together, our findings show that in human, LC ligation of TLR2 by S.a.-derived products down-regulates Fcε RI and its transcription factor PU.1, thus suggesting that Fcε RI is controlled by PU.1 in these cells. [ABSTRACT FROM AUTHOR]

Background: The Critical Care Air Transport (CCAT) Advanced Course utilizes fully immersive high-fidelity simulations to assess personnel readiness for deployment. This study aims to determine whether simple well-defined demographic identifiers can be used to predict CCAT students' performance at CCAT Advanced., Materials and Methods: CCAT Advanced student survey data and course status (pass/fail) between March 2006 and April 2020 were analyzed. The data included students' Air Force Specialty Code (AFSC), military status (active duty and reserve/guard), CCAT deployment experience (yes/no), prior CCAT Advanced training (yes/no), medical specialty, rank, and unit sustainment training frequency (never, frequency less often than monthly, and frequency at least monthly). Following descriptive analysis and comparative tests, multivariable regression was used to identify the predictors of passing the CCAT Advanced course for each provider type., Results: A total of 2,576 student surveys were analyzed: 694 (27%) physicians (MDs), 1,051 (40%) registered nurses (RNs), and 842 (33%) respiratory therapists (RTs). The overall passing rates were 92.2%, 90.3%, and 85.4% for the MDs, RNs, and RTs, respectively. The students were composed of 579 (22.5%) reserve/guard personnel, 636 (24.7%) with CCAT deployment experience, and 616 (23.9%) with prior CCAT Advanced training. Regression analysis identified groups with lower odds of passing; these included (1) RNs who promoted from Captain to Major (post-hoc analysis, P = .03), (2) RTs with rank Senior Airman, as compared to Master Sergeants (post-hoc analysis, P = .04), and (3) MDs with a nontraditional AFSC (P = .0004). Predictors of passing included MDs and RNs with CCAT deployment experience, odds ratio 2.97 (P = .02) and 2.65 (P = .002), respectively; and RTs who engaged in unit CCAT sustainment at least monthly (P = .02). The identifiers prior CCAT Advanced training or reserve/guard military status did not confer a passing advantage., Conclusion: Our main result is that simple readily available metrics available to unit commanders can identify those members at risk for poor performance at CCAT Advanced readiness training; these include RNs with rank Major or above, RTs with rank Senior Airman, and RTs who engage in unit sustainment training less often than monthly. Finally, MD specialties which are nontraditional for CCAT have significantly lower CCAT Advanced passing rates, reserve/guard students did not outperform active duty students, there was no difference in the performance between different RN specialties, and for MD and RN students' previous deployment experience was a strong predictor of passing., (© The Association of Military Surgeons of the United States 2024. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.)

Background: Janus kinase (JAK) inhibitors are a new class of therapeutic compounds for dermatological diseases. In atopic dermatitis (AD), data of clinical phase III trials show rapid improvement of pruritus and significant reduction of inflammation within the first weeks with a favorable safety profile. However, their mode of action in AD is not fully understood., Objectives: In our study, we investigate the effect of different JAK inhibitors on cell differentiation, phenotype, and function of inflammatory dendritic epidermal cells (IDECs)., Methods: We analyzed the JAK expression in IDEC from ex vivo skin and in vitro generated IDECs using flow cytometry and PCR. Further, we studied in vitro the effect of different JAK inhibitors on IDEC cell differentiation, phenotype, and maturation., Results: IDECs express JAK1 and JAK2 ex vivo and in vitro. We found that JAK1 and JAK2 were upregulated during the differentiation from monocytes to IDECs. Conversely, JAK2 inhibition by ruxolitinib (JAK1/2 inhibitor) or BMS-911543 (JAK2 inhibitor) abrogated the differentiation from monocytes into IDECs. Differentiated IDECs can redifferentiate into a more monocyte-like phenotype in the presence of ruxolitinib or BMS-911543. Furthermore, we showed that concomitant inhibition of JAK1/2 rather than blocking JAK1 or JAK2 alone, impaired maturation and the release of proinflammatory cytokines on lipopolysaccharide stimulation., Conclusions: Our results suggest that inhibition of JAK1/2 impairs IDEC differentiation and function. We provide new insight into the mode of action of JAK inhibitors in AD and highlight the role of JAK1/2 inhibitors for the treatment of patients with AD., (Copyright © 2020 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Atopic dermatitis (AD) is a severe inflammatory skin disease. Langerhans cells and inflammatory dendritic epidermal cells (IDEC) are located in the epidermis of AD patients and contribute to the inflammatory processes. Both express robustly the high-affinity receptor for IgE, FcεRI, and thereby sense allergens. A beneficial role of vitamin D 3 in AD is discussed to be important especially in patients with allergic sensitization. We hypothesized that vitamin D 3 impacts FcεRI expression and addressed this in human ex vivo skin, in vitro Langerhans cells, and IDEC models generated from primary human precursor cells. We show in this article that biologically active vitamin D 3 [1,25(OH) 2 -D 3 ] significantly downregulated FcεRI at the protein and mRNA levels of the receptor's α-chain, analyzed by flow cytometry and quantitative RT-PCR. We also describe the expression of a functional vitamin D receptor in IDEC. 1,25(OH) 2 -D 3 -mediated FcεRI reduction was direct and resulted in impaired activation of IDEC upon FcεRI engagement as monitored by CD83 expression. FcεRI regulation by 1,25(OH) 2 -D 3 was independent of maturation and expression levels of microRNA-155 and PU.1 (as upstream regulatory axis of FcεRI) and transcription factors Elf-1 and YY1. However, 1,25(OH) 2 -D 3 induced dissociation of PU.1 and YY1 from the FCER1A promotor, evaluated by chromatin immunoprecipitation. We show that vitamin D 3 directly reduces FcεRI expression on dendritic cells by inhibiting transcription factor binding to its promotor and subsequently impairs IgE-mediated signaling. Thus, vitamin D 3 as an individualized therapeutic supplement for those AD patients with allergic sensitization interferes with IgE-mediated inflammatory processes in AD patients., (Copyright © 2021 by The American Association of Immunologists, Inc.)

The bacterial cell envelope is believed to be a principal target for initiating the staphylocidal pathway of chitosan. The present study was therefore designed to investigate possible changes in cell surface phenotypes related to the in vitro chitosan resistance development in the laboratory strain S. aureus SG511-Berlin. Following a serial passage experiment, a stable chitosan-resistant variant (CRV) was identified, exhibiting >50-fold reduction in its sensitivity towards chitosan. Our analyses of the CRV identified phenotypic and genotypic features that readily distinguished it from its chitosan-susceptible parental strain, including: (i) a lower overall negative cell surface charge; (ii) cross-resistance to a number of antimicrobial agents; (iii) major alterations in cell envelope structure, cellular bioenergetics and metabolism (based on transcriptional profiling); and (iv) a repaired sensor histidine kinase GraS. Our data therefore suggest a close nexus between changes in cell envelope properties with the in vitro chitosan-resistant phenotype in S. aureus SG511-Berlin., (Copyright © 2016 Elsevier Ltd. All rights reserved.)