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Background: Epigenetic modifications are known to mediate both beneficial and unfavorable effects of environmental exposures on the development and clinical course of asthma. On the molecular level, epigenetic mechanisms participate in multiple aspects of the emerging and ongoing asthma pathology. Summary: Studies performed in the last several years expand our knowledge on the role of histone acetylation, a classical epigenetic mark, in the regulation of (patho)physiological processes of diverse cells playing a central role in asthma, including those belonging to the immune system (e.g., CD4+ T cells, macrophages) and lung structure (e.g., airway epithelial cells, pulmonary fibroblasts). Those studies demonstrate a number of specific histone acetylation-associated mechanisms and pathways underlying pathological processes characteristic for asthma, as well as report their modification modalities. Key Messages: Dietary modulation of histone acetylation levels in the immune system might protect against the development of asthma and other allergies. Interfering with the enzymes controlling the histone acetylation status of structural lung and (local) immune cells might provide future therapeutic options for asthmatics. Despite some methodological obstacles, analysis of the histone acetylation levels might improve asthma diagnostics. [ABSTRACT FROM AUTHOR]

Background: IL‐17A and TNF synergistically promote inflammation and tumorigenesis. Their interplay and impact on ovarian carcinoma (OC) progression are, however, poorly understood. We addressed this question focusing on mesothelial cells, whose interaction with tumor cells is known to play a pivotal role in transcoelomic metastasis formation. Methods: Flow‐cytometry and immunohistochemistry experiments were employed to identify cellular sources of IL‐17A and TNF. Changes in transcriptomes and secretomes were determined by bulk and single cell RNA sequencing as well as affinity proteomics. Functional consequences were investigated by microscopic analyses and tumor cell adhesion assays. Potential clinical implications were assessed by immunohistochemistry and survival analyses. Results: We identified Th17 cells as the main population of IL‐17A‐ and TNF producers in ascites and detected their accumulation in early omental metastases. Both IL‐17A and its receptor subunit IL‐17RC were associated with short survival of OC patients, pointing to a role in clinical progression. IL‐17A and TNF synergistically induced the reprogramming of mesothelial cells towards a pro‐inflammatory mesenchymal phenotype, concomitantly with a loss of tight junctions and an impairment of mesothelial monolayer integrity, thereby promoting cancer cell adhesion. IL‐17A and TNF synergistically induced the Th17‐promoting cytokines IL‐6 and IL‐1β as well as the Th17‐attracting chemokine CCL20 in mesothelial cells, indicating a reciprocal crosstalk that potentiates the tumor‐promoting role of Th17 cells in OC. Conclusions: Our findings reveal a novel function for Th17 cells in the OC microenvironment, which entails the IL‐17A/TNF‐mediated induction of mesothelial‐mesenchymal transition, disruption of mesothelial layer integrity and consequently promotion of OC cell adhesion. These effects are potentiated by a positive feedback loop between mesothelial and Th17 cells. Together with the observed clinical associations and accumulation of Th17 cells in omental micrometastases, our observations point to a potential role in early metastases formation and thus to new therapeutic options. [ABSTRACT FROM AUTHOR]

Alveolar type 2 and club cells are part of the stem cell niche of the lung and their differentiation is required for pulmonary homeostasis and tissue regeneration. A disturbed crosstalk between fibroblasts and epithelial cells contributes to the loss of lung structure in chronic lung diseases. Therefore, it is important to understand how fibroblasts and lung epithelial cells interact during regeneration. Here, we analyzed the interaction of fibroblasts and the alveolar epithelium modeled in air–liquid interface cultures. Single-cell transcriptomics showed that cocultivation with fibroblasts leads to increased expression of type 2 markers in pneumocytes, activation of regulons associated with the maintenance of alveolar type 2 cells (e.g., Etv5), and transdifferentiation of club cells toward pneumocytes. This was accompanied by an intensified transepithelial barrier. Vice versa, the activation of NF-κB pathways and the CEBPB regulon and the expression of IL-6 and other differentiation factors (e.g., fibroblast growth factors) were increased in fibroblasts cocultured with epithelial cells. Recombinant IL-6 enhanced epithelial barrier formation. Therefore, in our coculture model, regulatory loops were identified by which lung epithelial cells mediate regeneration and differentiation of the alveolar epithelium in a cooperative manner with the mesenchymal compartment. [ABSTRACT FROM AUTHOR]

Epithelial/immune interactions are characterized by the different properties of the various epithelial tissues, the mediators involved, and the varying immune cells that initiate, sustain, or abrogate allergic diseases on the surface. The intestinal mucosa, respiratory mucosa, and regular skin feature structural differences according to their primary function and surroundings. In the context of these specialized functions, the active role of the epithelium in shaping immune responses is increasingly recognizable. Crosstalk between epithelial and immune cells plays an important role in maintaining homeostatic conditions. While cells of the myeloid cell lineage, mainly macrophages, are the dominating immune cell population in the skin and the respiratory tract, lymphocytes comprise most intraepithelial immune cells in the intestine under healthy conditions. Common to all surface epithelia is the fact that innate immune cells represent the first line of immunosurveillance that either directly defeats invading pathogens or initiates and coordinates more effective successive immune responses involving adaptive immune cells and effector cells. Pharmacological approaches for the treatment of allergic and chronic inflammatory diseases involving epithelial barriers target immunological mediators downstream of the epithelium (such as IL‐4, IL‐5, IL‐13, and IgE). The next generation of therapeutics involves upstream events of the inflammatory cascade, such as epithelial‐derived alarmins and related mediators. [ABSTRACT FROM AUTHOR]

Rationale and Objective: Plasma extracellular vesicles (EVs) represent a vital source of molecular information about health and disease states. Due to their heterogenous cellular sources, EVs and their cargo may predict specific pathomechanisms behind disease phenotypes. Here we aimed to utilize EV microRNA (miRNA) signatures to gain new insights into underlying molecular mechanisms of obesity‐associated low type‐2 asthma. Methods: Obese low type‐2 asthma (OA) and non‐obese low type‐2 asthma (NOA) patients were selected from an asthma cohort conjointly with healthy controls. Plasma EVs were isolated and characterised by nanoparticle tracking analysis. EV‐associated small RNAs were extracted, sequenced and bioinformatically analysed. Results: Based on EV miRNA expression profiles, a clear distinction between the three study groups could be established using a principal component analysis. Integrative pathway analysis of potential target genes of the differentially expressed miRNAs revealed inflammatory cytokines (e.g., interleukin‐6, transforming growth factor‐beta, interferons) and metabolic factors (e.g., insulin, leptin) signalling pathways to be specifically associated with OA. The miR‐17–92 and miR‐106a–363 clusters were significantly enriched only in OA. These miRNA clusters exhibited discrete bivariate correlations with several key laboratory (e.g., C‐reactive protein) and lung function parameters. Plasma EV miRNA signatures mirrored blood‐derived CD4+ T‐cell transcriptome data, but achieved an even higher sensitivity in identifying specifically affected biological pathways. Conclusion: The identified plasma EV miRNA signatures and particularly the miR‐17–92 and ‐106a–363 clusters were capable to disentangle specific mechanisms of the obesity‐associated low type‐2 asthma phenotype, which may serve as basis for stratified treatment development. [ABSTRACT FROM AUTHOR]

The global burden of respiratory diseases is very high and still on the rise, prompting the need for accurate models for basic and translational research. Several model systems are currently available ranging from simple airway cell cultures to complex tissue-engineered lungs. In recent years, human lung organoids have been established as highly transferrable three-dimensional in vitro model systems for lung research. For acute infectious and chronic inflammatory diseases as well as lung cancer, human lung organoids have opened possibilities for precise in vitro research and a deeper understanding of mechanisms underlying lung injury and regeneration. Human lung organoids from induced pluripotent stem cells or from adult stem cells of patients' samples introduce tools for understanding developmental processes and personalized medicine approaches. When further state-of-the-art technologies and protocols come into use, the full potential of human lung organoids can be harnessed. High-throughput assays in drug development, gene therapy, and organoid transplantation are current applications of organoids in translational research. In this review, we emphasize novel approaches in translational and personalized medicine in lung research focusing on the use of human lung organoids. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) gain increasing attention due to their (patho-)physiological role in intercellular signaling, specifically in the communication between distant organs. Recent studies highlight a connection between the adipose tissue (AT) and the lung via (immuno-)modulatory EVs in disorders such as obesity-associated asthma and lung cancer-associated cachexia. Although lung cancer-derived EVs induce lipolysis and myotube atrophy in vivo, pathogenic effects were also reported in the opposite direction with the involvement of AT-derived EVs in cancer-promoting responses and potentially in asthma development. In contrast, the majority of studies on AT-derived EVs demonstrate their protective influence on the asthmatic lung. Beneficial effects, such as induction of anti-inflammatory pathways in vitro and in ovalbumin (OVA)-induced asthma mouse models, were particularly conveyed by EVs enriched from AT-derived mesenchymal stem/stromal cells (AT-MSCs), which therefore pose an interesting subject in possible future therapeutic applications. Likewise, AT-MSC-derived EVs exerted beneficial effects in several other pulmonary abnormalities, such as different types of lung injury or pathological changes related to chronic obstructive pulmonary disease. These contradictory findings highlight the need for extensive research to widen the understanding of the role of EVs in the development of diseases and interconnectivity between organs. [ABSTRACT FROM AUTHOR]

Background: Early‐life exposure to certain environmental bacteria including Acinetobacter lwoffii (AL) has been implicated in protection from chronic inflammatory diseases including asthma later in life. However, the underlying mechanisms at the immune‐microbe interface remain largely unknown. Methods: The effects of repeated intranasal AL exposure on local and systemic innate immune responses were investigated in wild‐type and Il6−/−, Il10−/−, and Il17−/− mice exposed to ovalbumin‐induced allergic airway inflammation. Those investigations were expanded by microbiome analyses. To assess for AL‐associated changes in gene expression, the picture arising from animal data was supplemented by in vitro experiments of macrophage and T‐cell responses, yielding expression and epigenetic data. Results: The asthma preventive effect of AL was confirmed in the lung. Repeated intranasal AL administration triggered a proinflammatory immune response particularly characterized by elevated levels of IL‐6, and consequently, IL‐6 induced IL‐10 production in CD4+ T‐cells. Both IL‐6 and IL‐10, but not IL‐17, were required for asthma protection. AL had a profound impact on the gene regulatory landscape of CD4+ T‐cells which could be largely recapitulated by recombinant IL‐6. AL administration also induced marked changes in the gastrointestinal microbiome but not in the lung microbiome. By comparing the effects on the microbiota according to mouse genotype and AL‐treatment status, we have identified microbial taxa that were associated with either disease protection or activity. Conclusion: These experiments provide a novel mechanism of Acinetobacter lwoffii‐induced asthma protection operating through IL‐6‐mediated epigenetic activation of IL‐10 production and with associated effects on the intestinal microbiome. [ABSTRACT FROM AUTHOR]

This document is a reply to a correspondence letter regarding a scientific study on obese asthmatics. The authors clarify that their primary aim was to gain insights into the underlying mechanisms of obesity-associated low type-2 asthma, rather than establish diagnostic biomarkers. They mention that further validation is needed for the identified microRNA markers. The authors also address questions about the cell types responsible for the release of extracellular vesicles with different microRNA cargo in obese asthmatics. The study was supported by various funding sources and the authors declare no conflicts of interest. [Extracted from the article]

Optimal pre-analytical conditions for blood sample processing and isolation of selected cell populations for subsequent transcriptomic and epigenomic studies are required to obtain robust and reproducible results. This pilot study was conducted to investigate the potential effects of timing of CD4+ T-cell processing from peripheral blood of atopic and non-atopic adults on their transcriptomic and epigenetic profiles. Two heparinized blood samples were drawn from each of three atopic and three healthy individuals. For each individual, CD4+ T-cells were isolated from the first blood sample within 2 h (immediate) or from the second blood sample after 24 h storage (delayed). RNA sequencing (RNA-Seq) and histone H3K27 acetylation chromatin immunoprecipitation sequencing (ChIP-Seq) analyses were performed. A multiplicity of genes was shown to be differentially expressed in immediately processed CD4+ T-cells from atopic versus healthy subjects. These differences disappeared when comparing delayed processed cells due to a drastic change in expression levels of atopy-related genes in delayed processed CD4+ T-cells from atopic donors. This finding was further validated on the epigenomic level by examining H3K27 acetylation profiles. In contrast, transcriptomic and epigenomic profiles of blood CD4+ T-cells of healthy donors remained rather unaffected. Taken together, for successful transcriptomics and epigenomics studies, detailed standard operation procedures developed on the basis of samples from both healthy and disease conditions are implicitly recommended. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) are released by virtually all cells and may serve as intercellular communication structures by transmitting molecules such as proteins, lipids, and nucleic acids between cells. MicroRNAs (miRNAs) are an abundant class of vesicular RNA playing a pivotal role in regulating intracellular processes. In this work, we aimed to characterize vesicular miRNA profiles released in a side-directed manner by bronchial epithelial cells from healthy and asthmatic subjects using an air−liquid interface cell culture model. EVs were isolated from a culture medium collected from either the basolateral or apical cell side of the epithelial cell cultures and characterized by nano-flow cytometry (NanoFCM) and bead-based flow cytometry. EV-associated RNA profiles were assessed by small RNA sequencing and subsequent bioinformatic analyses. Furthermore, miRNA-associated functions and targets were predicted and miRNA network analyses were performed. EVs were released at higher numbers to the apical cell side of the epithelial cells and were considerably smaller in the apical compared to the basolateral compartment. EVs from both compartments showed a differential tetraspanins surface marker expression. Furthermore, 236 miRNAs were differentially expressed depending on the EV secretion side, regardless of the disease phenotype. On the apical cell side, 32 miRNAs were significantly altered in asthmatic versus healthy conditions, while on the basolateral cell side, 23 differentially expressed miRNAs could be detected. Downstream KEGG pathway analysis predicted mTOR and MAPK signaling pathways as potential downstream targets of apically secreted miRNAs. In contrast, miRNAs specifically detected at the basolateral side were associated with processes of T and B cell receptor signaling. The study proves a compartmentalized packaging of EVs by bronchial epithelial cells supposedly associated with site-specific functions of cargo miRNAs, which are considerably affected by disease conditions such as asthma. [ABSTRACT FROM AUTHOR]

Aspirin-exacerbated respiratory disease (AERD) is characterized by overproduction of the pro-inflammatory eicosanoids. Although immunoglobulin E-mediated sensitization to aeroallergens is common among AERD patients, it does not belong to the defining disease characteristics. In this study of 133 AERD patients, we sought to find a relationship between sensitization to aeroallergens and local (leukotriene E4, prostaglandin E2 and prostaglandin D2) and/or systemic (leukotriene E4) production of arachidonic acid metabolites. Interestingly, a negative association between pro-inflammatory eicosanoid levels in induced sputum supernatant or urine and sensitization to aeroallergens was observed. This inverse relationship might suggest the presence of a protective effect of atopic sensitization to aeroallergens against stronger local airway inflammation and higher systemic AERD-related inflammatory activity. [ABSTRACT FROM AUTHOR]

Background: While childhood asthma prevalence is rising in Westernized countries, farm children are protected. The mitogen‐activated protein kinase (MAPK) pathway with its negative regulator dual‐specificity phosphatase‐1 (DUSP1) is presumably associated with asthma development. Objectives: We aimed to investigate the role of MAPK signaling in childhood asthma and its environment‐mediated protection, including a representative selection of 232 out of 1062 children from two cross‐sectional cohorts and one birth cohort study. Methods: Peripheral blood mononuclear cells (PBMC) from asthmatic and healthy children were cultured upon stimulation with farm‐dust extracts or lipopolysaccharide. In subgroups, gene expression was analyzed by qPCR (PBMCs, cord blood) and NanoString technology (dendritic cells). Protein expression of phosphorylated MAPKs was measured by mass cytometry. Histone acetylation was investigated by chromatin immunoprecipitation. Results: Asthmatic children expressed significantly less DUSP1 (p =.006) with reduced acetylation at histone H4 (p =.012) compared with healthy controls. Farm‐dust stimulation upregulated DUSP1 expression reaching healthy levels and downregulated inflammatory MAPKs on gene and protein levels (PBMCs; p ≤.01). Single‐cell protein analysis revealed downregulated pMAPKs upon farm‐dust stimulation in B cells, NK cells, monocytes, and T‐cell subpopulations. Conclusion: Lower DUSP1 baseline levels in asthmatic children and anti‐inflammatory regulation of MAPK in several immune cell types by farm‐dust stimulation indicate a regulatory function for DUSP1 for future therapy contributing to anti‐inflammatory characteristics of farming environments. [ABSTRACT FROM AUTHOR]

Background: While several systemic immunomodulatory effects of allergen‐specific immunotherapy (AIT) have been discovered, local anti‐inflammatory mechanisms in the respiratory tract are largely unknown. We sought to elucidate local and epithelial mechanisms underlying allergen‐specific immunotherapy in a genome‐wide approach. Methods: We induced sputum in hay fever patients and healthy controls during the pollen peak season and stratified patients by effective allergen immunotherapy or as untreated. Sputum was directly processed after induction and subjected to whole transcriptome RNA microarray analysis. Nasal secretions were analyzed for Secretoglobin1A1 (SCGB1A1) and IL‐24 protein levels in an additional validation cohort at three defined time points during the 3‐year course of AIT. Subsequently, RNA was extracted and subjected to an array‐based whole transcriptome analysis. Results: Allergen‐specific immunotherapy inhibited pro‐inflammatory CXCL8, IL24, and CCL26mRNA expression, while SCGB1A1, IL7, CCL5, CCL23, and WNT5BmRNAs were induced independently of the asthma status and allergen season. In our validation cohort, local increase of SCGB1A1 occurred concomitantly with the reduction of local IL‐24 in upper airways during the course of AIT. Additionally, SCGB1A1 was identified as a suppressor of epithelial gene expression. Conclusions: Allergen‐specific immunotherapy induces a yet unknown local gene expression footprint in the lower airways that on one hand appears to be a result of multiple regulatory pathways and on the other hand reveals SCGB1A1 as novel anti‐inflammatory mediator of long‐term allergen‐specific therapeutic intervention in the local environment. [ABSTRACT FROM AUTHOR]