Histamine and Th2 cytokines independently and synergistically upregulate MMP12 expression in human M2 macrophages.

Beyond Th2 cells and various immune cells, M2 macrophages have been identified in lesional skin of atopic dermatitis (AD) indicating their involvement in the disease's underlying mechanisms. MMP12, a matrix-degrading enzyme, which is predominantly produced by macrophages, is increased in skin lesions of AD patients. In this study we investigated the expression of MMP12 mRNA in lesional AD skin at single cell level through RNA sequencing (scRNA-seq) and the expression of MMP12 in M2 macrophages from healthy individuals and AD patients in response to Th2 cytokines and histamine using quantitative PCR and ELISA. Additionally, we analyzed macrophages from dupilumab-treated AD patients using the same methods to assess the influence of Th2 cytokines on MMP12 expression ex-vivo. ScRNA-seq identified macrophages as the primary producers of MMP12 in lesional AD skin. In-vitro, both MMP12 mRNA and protein expression were significantly increased in monocytes during differentiation to M2 macrophages in the presence of histamine, of Th2 cytokines or of Th2 cytokines in combination with histamine. In M2 macrophages obtained from dupilumab-treated AD patients, the upregulation of MMP12 expression by IL-4 and IL-13 was attenuated. Our findings unveil a novel mechanism whereby Th2 cytokines and histamine regulate MMP12 expression, potentially impacting skin barrier homeostasis in AD.

The antimicrobial protein RNase 7 directly restricts herpes simplex virus infection of human keratinocytes.

Approximately 22% of moderately to severely affected atopic dermatitis (AD) patients have a history of eczema herpeticum, a disseminated rash primarily caused by herpes simplex virus type 1 (HSV-1). Reduced activity of antimicrobial peptides may contribute to the increased susceptibility of AD patients to HSV-1. We previously demonstrated that the antimicrobial protein RNase 7 limits HSV-1 infection of human keratinocytes by promoting self-DNA sensing. Here, we addressed whether RNase 7 has any effect on HSV-1 infection when infecting keratinocytes without exogenously added costimulatory DNA, and which step(s) of the infection cycle RNase 7 interferes with. We quantified viral gene expression by RT-qPCR and flow cytometry, viral genome replication by qPCR, virucidal effects by plaque titration, and plaque formation and the subcellular localization of incoming HSV-1 particles by microscopy. Recombinant RNase 7 restricted HSV-1 gene expression, genome replication, and plaque formation in human keratinocytes. It decreased HSV-1 immediate-early transcripts independently of the induction of interferon-stimulated genes. Its main effect was on intracellular infection processes and not on extracellular virions or virus binding to cells. RNase 7 reduced the amount of cell-associated capsids and the HSV-1 envelope glycoprotein D at 3 but not at 0.5 h postinfection. Our data show that RNase 7 directly restricts HSV-1 infection of human keratinocytes, possibly by promoting the degradation of incoming HSV-1 particles. This suggests that RNase 7 may limit HSV-1 spread in the skin and that mechanisms that reduce its activity in the lesional skin of AD patients may increase their susceptibility to eczema herpeticum.

Glycopolymeric Nanoparticles Enrich Less Immunogenic Protein Coronas, Reduce Mononuclear Phagocyte Clearance, and Improve Tumor Delivery Compared to PEGylated Nanoparticles.

Nanoparticles (NPs) offer significant promise as drug delivery vehicles; however, their in vivo efficacy is often hindered by the formation of a protein corona (PC), which influences key physiological responses such as blood circulation time, biodistribution, cellular uptake, and intracellular localization. Understanding NP-PC interactions is crucial for optimizing NP design for biomedical applications. Traditional approaches have utilized hydrophilic polymer coatings like polyethylene glycol (PEG) to resist protein adsorption, but glycopolymer-coated nanoparticles have emerged as potential alternatives due to their biocompatibility and ability to reduce the adsorption of highly immunogenic proteins. In this study, we synthesized and characterized glycopolymer-based poly[2-(diisopropylamino)ethyl methacrylate-b-poly(methacrylamidoglucopyranose) (PDPA-b-PMAG) NPs as an alternative to PEGylated NPs. We characterized the polymers using a range of techniques to establish their molecular weight and chemical composition. PMAG and PEG-based NPs showed equivalent physicochemical properties with sizes of ∼100 nm, spherical morphology, and neutral surface charges. We next assessed the magnitude of protein adsorption on both NPs and catalogued the identity of the adsorbed proteins using mass spectrometry-based techniques. The PMAG NPs were found to adsorb fewer proteins in vitro as well as fewer immunogenic proteins such as Immunoglobulins and Complement proteins. Flow cytometry and confocal microscopy were employed to examine cellular uptake in RAW 264.7 macrophages and MDA-MB-231 tumor cells, where PMAG NPs showed higher uptake into tumor cells over macrophages. In vivo studies in BALB/c mice with orthotopic 4T1 breast cancer xenografts showed that PMAG NPs exhibited prolonged circulation times and enhanced tumor accumulation compared to PEGylated NPs. The biodistribution analysis also revealed greater selectivity for tumor tissue over the liver for PMAG NPs. These findings highlight the potential of glycopolymeric NPs to improve tumor targeting and reduce macrophage uptake compared to PEGylated NPs, offering significant advancements in cancer nanomedicine and immunotherapy.

Short-form thymic stromal lymphopoietin (sfTSLP) restricts herpes simplex virus infection of human primary keratinocytes.

Eczema herpeticum (EH) is a disseminated severe herpes simplex virus type 1 (HSV-1) infection that mainly occurs in a subset of patients suffering from atopic dermatitis (AD). EH is complex and multifaceted, involving immunological changes, environmental influences, and genetic aberrations. Certain genetic variants of the thymic stromal lymphopoietin (TSLP) may predispose to develop severe HSV-1-induced eczema. Therefore, we investigated the impact of TSLP on HSV-1 infection. TSLP encodes for two distinct forms: a long-form (lfTSLP), primarily associated with type 2 immunity, and a short-form (sfTSLP) with anti-inflammatory and antimicrobial properties. While sfTSLP reduced HSV-1 infectibility in human primary keratinocytes (HPK), lfTSLP did not. In HPK treated with sfTSLP, HSV-1 gene expression, and replication decreased, while virion binding to cells and targeting of incoming capsids to the nucleus were not diminished compared to untreated cells. sfTSLP caused only minor changes in the expression of innate immunity cytokines, and its inhibition of HSV-1 infection did not require de novo protein synthesis. Time window experiments indicated a different antiviral mechanism than LL-37. sfTSLP showed the strongest antiviral effect when administered to HPK before or after inoculation with HSV-1, and outperformed the inhibitory potential of LL-37 under these conditions. Our data show that sfTSLP has antiviral functions and promotes repression of the HSV-1 infection in HPK.

The RESIST Senior Individuals Cohort: Design, participant characteristics and aims.

The number of older adults worldwide is growing exponentially. However, while living longer, older individuals are more susceptible to both non-infectious and infectious diseases, at least in part due to alterations of the immune system. Here, we report on a prospective cohort study investigating the influence of age on immune responses and susceptibility to infection. The RESIST Senior Individuals (SI) cohort was established as a general population cohort with a focus on the elderly, enrolling an age- and sex-stratified sample of 650 individuals (n = 100 20-39y, n = 550 61-94y, 2019-2023, Hannover, Germany). It includes clinical, demographic, and lifestyle data and also extensive biomaterial sampling. Initial insights indicate that the SI cohort exhibits characteristics of the aging immune system and the associated susceptibility to infection, thereby providing a suitable platform for the decoding of age-related alterations of the immune system and unraveling the molecular mechanisms underlying the impaired immune responsiveness in aging populations by exploring comprehensive, unbiased multi-omics datasets.

The stimulation of TH2 cells results in increased IL-5 and IL-13 production via the H4 receptor.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease resulting in decreased quality of life. Histamine and specifically the H4 receptor play a key role in the inflammatory process in AD and serve as targets for novel therapeutic approaches. OBJECTIVE: In the present study we aimed to elucidate the immunopathological mechanisms with which the H4 receptor impacts TH2 cells and contributes to AD pathophysiology. METHODS: Total CD4+ T cells obtained from healthy or AD individuals and in vitro differentiated TH2 cells were cultured under different conditions and the mRNA expression or protein production of target molecules were determined using quantitative real-time PCR and ELISA. RESULTS: H4 receptor mRNA expression was upregulated concentration dependent upon IL-4 stimulation in in vitro differentiated TH2 cells progressively during the differentiation. Transcriptomic analysis of in vitro differentiated TH2 versus TH1 cells revealed that the H4 receptor among other genes represents one of the highly upregulated genes in TH2 cells. Most importantly, increased amounts of IL-5 and IL-13 mRNA expression were detected in in vitro differentiated TH2 cells as well as protein secretion in the presence of histamine or of the H4 receptor-selective-agonist when compared to the untreated control. CONCLUSION: We show for the first time an H4 receptor dependent upregulation of the pro-inflammatory cytokines IL-5 and IL-13 in human TH2 cells by histamine. This suggests that the blockade of the H4 receptor may lead to downregulation of these cytokines and amelioration of AD symptoms as reported in first clinical studies.

Polymeric Micellar Nanoparticles Enable Image-guided Drug Delivery in Solid Tumors.

We report the development of a nanotechnology to co-deliver chemocoxib A with a reactive oxygen species (ROS)-activatable and COX-2 targeted pro-fluorescent probe, fluorocoxib Q (FQ) enabling real time visualization of COX-2 and CA drug delivery into solid cancers, using a di-block PPS 135 - b -POEGA 17 copolymer, selected for its intrinsic responsiveness to elevated reactive oxygen species (ROS), a key trait of the tumor microenvironment. FQ and CA were synthesized independently, then co-encapsulated within micellar PPS 135 - b -POEGA 17 co-polymeric nanoparticles (FQ-CA-NPs), and were assessed for cargo concentration, hydrodynamic diameter, zeta potential, and ROS-dependent cargo release. The uptake of FQ-CA-NPs in mouse mammary cancer cells and cargo release was assessed by fluorescence microscopy. Intravenous delivery of FQ-CA-NPs to mice harboring orthotopic mammary tumors, followed by vital optimal imaging, was used to assess delivery to tumors in vivo . The CA-FQ-NPs exhibited a hydrodynamic diameter of 109.2 ± 4.1 nm and a zeta potential (σ) of -1.59 ± 0.3 mV. Fluorescence microscopy showed ROS-dependent cargo release by FQ-CA-NPs in 4T1 cells, decreasing growth of 4T1 breast cancer cells, but not affecting growth of primary human mammary epithelial cells (HMECs). NP-derived fluorescence was detected in mammary tumors, but not in healthy organs. Tumor LC-MS/MS analysis identified both CA (2.38 nmol/g tumor tissue) and FQ (0.115 nmol/g tumor tissue), confirming the FQ-mediated image guidance of CA delivery in solid tumors. Thus, co-encapsulation of FQ and CA into micellar nanoparticles (FQ-CA-NPs) enabled ROS-sensitive drug release and COX-2-targeted visualization of solid tumors.

The extracellular serine protease from Staphylococcus epidermidis elicits a type 2-biased immune response in atopic dermatitis patients.

Background: Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease with skin barrier defects and a misdirected type 2 immune response against harmless antigens. The skin microbiome in AD is characterized by a reduction in microbial diversity with a dominance of staphylococci, including Staphylococcus epidermidis (S. epidermidis). Objective: To assess whether S. epidermidis antigens play a role in AD, we screened for candidate allergens and studied the T cell and humoral immune response against the extracellular serine protease (Esp). Methods: To identify candidate allergens, we analyzed the binding of human serum IgG4, as a surrogate of IgE, to S. epidermidis extracellular proteins using 2-dimensional immunoblotting and mass spectrometry. We then measured serum IgE and IgG1 binding to recombinant Esp by ELISA in healthy and AD individuals. We also stimulated T cells from AD patients and control subjects with Esp and measured the secreted cytokines. Finally, we analyzed the proteolytic activity of Esp against IL-33 and determined the cleavage sites by mass spectrometry. Results: We identified Esp as the dominant candidate allergen of S. epidermidis. Esp-specific IgE was present in human serum; AD patients had higher concentrations than controls. T cells reacting to Esp were detectable in both AD patients and healthy controls. The T cell response in healthy adults was characterized by IL-17, IL-22, IFN-γ, and IL-10, whereas the AD patients' T cells lacked IL-17 production and released only low amounts of IL-22, IFN-γ, and IL-10. In contrast, Th2 cytokine release was higher in T cells from AD patients than from healthy controls. Mature Esp cleaved and activated the alarmin IL-33. Conclusion: The extracellular serine protease Esp of S. epidermidis can activate IL-33. As an antigen, Esp elicits a type 2-biased antibody and T cell response in AD patients. This suggests that S. epidermidis can aggravate AD through the allergenic properties of Esp.

A comprehensive genetic map of cytokine responses in Lyme borreliosis.

The incidence of Lyme borreliosis has risen, accompanied by persistent symptoms. The innate immune system and related cytokines are crucial in the host response and symptom development. We characterized cytokine production capacity before and after antibiotic treatment in 1,060 Lyme borreliosis patients. We observed a negative correlation between antibody production and IL-10 responses, as well as increased IL-1Ra responses in patients with disseminated disease. Genome-wide mapping the cytokine production allowed us to identify 34 cytokine quantitative trait loci (cQTLs), with 31 novel ones. We pinpointed the causal variant at the TLR1-6-10 locus and validated the regulation of IL-1Ra responses at transcritpome level using an independent cohort. We found that cQTLs contribute to Lyme borreliosis susceptibility and are relevant to other immune-mediated diseases. Our findings improve the understanding of cytokine responses in Lyme borreliosis and provide a genetic map of immune function as an expanded resource.

Single-cell RNA sequencing reveals 2D cytokine assay can model atopic dermatitis more accurately than immune-competent 3D setup.

Modelling atopic dermatitis (AD) in vitro is paramount to understand the disease pathophysiology and identify novel treatments. Previous studies have shown that the Th2 cytokines IL-4 and IL-13 induce AD-like features in keratinocytes in vitro. However, it has not been systematically researched whether the addition of Th2 cells, their supernatants or a 3D structure is superior to model AD compared to simple 2D cell culture with cytokines. For the first time, we investigated what in vitro option most closely resembles the disease in vivo based on single-cell RNA sequencing data (scRNA-seq) obtained from skin biopsies in a clinical study and published datasets of healthy and AD donors. In vitro models were generated with primary fibroblasts and keratinocytes, subjected to cytokine treatment or Th2 cell cocultures in 2D/3D. Gene expression changes were assessed using qPCR and Multiplex Immunoassays. Of all cytokines tested, incubation of keratinocytes and fibroblasts with IL-4 and IL-13 induced the closest in vivo-like AD phenotype which was observed in the scRNA-seq data. Addition of Th2 cells to fibroblasts failed to model AD due to the downregulation of ECM-associated genes such as POSTN. While keratinocytes cultured in 3D showed better stratification than in 2D, changes induced with AD triggers did not better resemble AD keratinocyte subtypes observed in vivo. Taken together, our comprehensive study shows that the simple model using IL-4 or IL-13 in 2D most accurately models AD in fibroblasts and keratinocytes in vitro, which may aid the discovery of novel treatment options.

Modelling atopic dermatitis in healthy human skin for the characterization of topical compounds.

Suitable human models for the development and characterization of topical compounds for inflammatory skin diseases such as atopic dermatitis are not readily available to date. We describe here the development of a translational model involving healthy human skin mimicking major aspects of AD and its application for the characterization of topical Janus kinase inhibitors. Full thickness human abdominal skin obtained from plastic surgery stimulated in vitro with IL4 and IL13 shows molecular features of AD. This is evidenced by STAT6 phosphorylation assessed by immunohistochemistry and analysis of skin lysates. Broad transcriptome changes assessed by AmpliSeq followed by gene set variation analysis showed a consistent upregulation of gene signatures characterizing AD in this model. Topical application of experimental formulations of compounds targeting the JAK pathway to full thickness skin normalizes the molecular features of AD induced by IL4 and IL13 stimulation. The inhibitory effects of topical JAK inhibitors on molecular features of AD are supported by pharmacokinetic analysis. The model described here is suited for the characterization of topical compounds for AD and has the potential to be extended to other inflammatory skin diseases and pathophysiological pathways.

Italian S3-Guideline on the treatment of Atopic Eczema - Part 1: Systemic therapy, adapted from EuroGuiDerm by the Italian Society of Dermatology and STD (SIDEMAST), the Italian Association of Hospital Dermatologists (ADOI) and the Italian Society of Allergological and Environmental Dermatology (SIDAPA).

SIDeMaST (Società Italiana di Dermatologia Medica, Chirurgica, Estetica e delle Malattie Sessualmente Trasmesse) contributed to the development of the present guideline on the systemic treatment of chronic plaque psoriasis. With the permission of EuroGuiDerm, SIDeMaST adapted the guideline to the Italian healthcare context to supply a reliable and affordable tool to Italian physicians who take care of patients affected by atopic dermatitis. The evidence- and consensus-based guideline on atopic eczema was developed in accordance with the EuroGuiDerm Guideline and Consensus Statement Development Manual. Four consensus conferences were held between December 2020 and July 2021. Twenty-nine experts (including clinicians and patient representatives) from 12 European countries participated. This first part of the guideline includes general information on its scope and purpose, the health questions covered, target users and a methods section. It also provides guidance on which patients should be treated with systemic therapies, as well as recommendations and detailed information on each systemic drug. The systemic treatment options discussed in the guideline comprise conventional immunosuppressive drugs (azathioprine, ciclosporin, glucocorticosteroids, methotrexate and mycophenolate mofetil), biologics (dupilumab, lebrikizumab, nemolizumab, omalizumab and tralokinumab) and janus kinase inhibitors (abrocitinib, baricitinib and upadacitinib). Part two of the guideline will address avoidance of provocation factors, dietary interventions, immunotherapy, complementary medicine, educational interventions, occupational and psychodermatological aspects, patient perspective and considerations for pediatric, adolescent, pregnant and breastfeeding patients.

Italian S3-Guideline on the treatment of Atopic Eczema - Part 2: non-systemic treatments and treatment recommendations for special AE patient populations, adapted from EuroGuiDerm by the Italian Society of Dermatology and STD (SIDEMAST), the Italian Association of Hospital Dermatologists (ADOI) and the Italian Society of Allergological and Occupational Dermatology (SIDAPA).

SIDeMaST (Società Italiana di Dermatologia Medica, Chirurgica, Estetica e delle Malattie Sessualmente Trasmesse) contributed to the development of the present guideline on the systemic treatment of chronic plaque psoriasis. With the permission of EuroGuiDerm, SIDeMaST adapted the guideline to the Italian healthcare context to supply a reliable and affordable tool to Italian physicians who take care of patients affected by atopic dermatitis. The evidence- and consensus-based guideline on atopic eczema was developed in accordance with the EuroGuiDerm Guideline and Consensus Statement Development Manual. Four consensus conferences were held between December 2020 and July 2021. Twenty-nine experts (including clinicians and patient representatives) from 12 European countries participated. This second part of the guideline includes recommendations and detailed information on basic therapy with emollients and moisturizers, topical anti-inflammatory treatment, antimicrobial and antipruritic treatment and UV phototherapy. Furthermore, this part of the guideline covers techniques for avoiding provocation factors, as well as dietary interventions, immunotherapy, complementary medicine and educational interventions for patients with atopic eczema and deals with occupational and psychodermatological aspects of the disease. It also contains guidance on treatment for pediatric and adolescent patients and pregnant or breastfeeding women, as well as considerations for patients who want to have a child. A chapter on the patient perspective is also provided. The first part of the guideline, published separately, contains recommendations and guidance on systemic treatment with conventional immunosuppressive drugs, biologics and janus kinase (JAK) inhibitors, as well as information on the scope and purpose of the guideline, and a section on guideline methodology.

Italian S3-Guideline on the treatment of Atopic Eczema - First Update, adapted from EuroGuiDerm by the Italian Society of Dermatology and STD (SIDEMAST), the Italian Association of Hospital Dermatologists (ADOI) and the Italian Society of Allergological and Occupational Dermatology (SIDAPA).

The evidence- and consensus-based guideline on atopic eczema, published in JEADV on 18 August 2022 (part 1) and 3 September 2022 (part 2) was developed in accordance with the EuroGuiDerm Guideline and Consensus Statement Development Manual. Four consensus conferences were held between December 2020 and July 2021. Twenty-nine experts (including clinicians and patient representatives) from 12 European countries participated. To reflect the most recent evidence on novel systemic medications, an update was published in October 2022. According to the purpose of the Italian Society of Dermatology and STD (SIDEMAST), the Italian Association of Hospital Dermatologists (ADOI) and the Italian Society of Allergological and Environmental Dermatology (SIDAPA) to adapt the EuroGuiDerm guideline on the treatment of atopic eczema into the Italian Healthcare setting, the original update has been supplemented by inserting notes, well highlighted by the original text, to emphasize the laws, rules, procedures and suggestions of the Italian Ministry of Health and regional Health authorities.

Hand eczema symptoms, exposures and skin care in orthodontics : A national, cross-sectional questionnaire-based survey.

OBJECTIVES: Occupational hand eczema is a common inflammatory skin condition among healthcare professionals. Orthodontists are frequently exposed to a variety of irritating and allergenic substances, and therefore they belong to a predisposed group to develop hand eczema. However, current data on the prevalence and predisposing factors among orthodontists to provide adequate prophylaxis are lacking. METHODS: An anonymous online survey was conducted in Germany between January and February 2023 and distributed to 2402 orthodontists. The questionnaire addressed general information on current skin status, as well as occupational skin exposure and skin care. RESULTS: A total of 209 orthodontists responded to the survey. Seventy-four percent reported experiencing hand eczema-specific symptoms within the last 12 months, with 24% describing moderate and 10% describing severe symptoms. The average daily glove wearing time was stated to be 6 ± 2 h. The most frequently reported triggers at work were frequent hand washing (62.7%) and hand disinfection (59.1%). Among all the respondents, 22.6% stated not using either barrier cream or moisturizer. CONCLUSIONS: This study showed a high prevalence of hand eczema symptoms among orthodontists, which is probably due to frequent disinfection, hand washing, and contact with allergens such as acrylates. In this professional group especially, against a background of future increasing acrylate and epoxy resin exposures due to in-office three-dimensional printing processes, timely education and skin protection could decisively counteract the pathogenesis of hand eczema.

Inhibition of RNase 7 by RNase inhibitor promotes inflammation and Staphylococcus aureus growth: Implications for atopic dermatitis.

BACKGROUND: The antimicrobial ribonuclease RNase 7 is abundantly expressed in the epidermis of lesional skin of atopic dermatitis (AD). Host RNase inhibitor (RI) binds to RNase 7 and blocks its ribonuclease activity. This study aimed to evaluate the impact of RNase 7-RI interactions on AD. METHODS: Cultured human primary keratinocytes, with siRNA-mediated downregulation of RNase 7 and RI, were stimulated with the synthetic RNA polyinosinic-polycytidylic acid (poly I:C). Induction of proinflammatory mediators was analyzed by real-time PCR and ELISA. RI expression in AD non-lesional and lesional skin biopsies and healthy controls was analyzed by real-time PCR and immunostaining. RI protein release in vivo on the AD skin surface was determined by western blot. Antimicrobial and ribonuclease assays were used to investigate the functional role of RI. RESULTS: RNase 7 inhibited the RNA-induced expression of proinflammatory mediators in keratinocytes. Accordingly, downregulation of RNase 7 in keratinocytes enhanced RNA-mediated induction of proinflammatory mediators, whereas downregulation of RI had the opposite effect. RI was released by damaged keratinocytes and epidermis. In vivo expression and release of RI on the skin surface were enhanced in lesional AD skin. Rinsing solution from the surface of lesional AD skin blocked the ribonuclease activity of RNase 7. The anti-Staphylococcus aureus activity of RNase 7 was abrogated by RI. CONCLUSIONS: Our data suggest a novel role of RI as a trigger factor of inflammation in AD by blocking the ribonuclease and antimicrobial activity of RNase 7, thereby enhancing RNA-mediated inflammation and S. aureus growth.