Human cells release nano-sized vesicles called exosomes, containing mRNA, miRNA and specific proteins. Exosomes from one cell can be taken up by another cell, which is a recently discovered cell-to-cell communication mechanism. Also, exosomes can be taken up by different types of cancer cells, but the potential functional effects of mast cell exosomes on tumor cells remain unknown. Exosomes were isolated from the human mast cell line, HMC-1, and uptake of PKH67-labelled exosomes by the lung epithelial cell line, A549, was examined using flow cytometry and fluorescence microscopy. The RNA cargo of the exosomes was analyzed with a Bioanalyzer and absence or presence of the c-KIT mRNA was determined by RT-PCR. The cell proliferation was determined in a BrdU incorporation assay, and proteins in the KIT-SCF signaling pathway were detected by Western blot. Our result demonstrates that exosomes from mast cells can be taken up by lung cancer cells. Furthermore, HMC-1 exosomes contain and transfer KIT protein, but not the c-KIT mRNA to A549 cells and subsequently activate KIT-SCF signal transduction, which increase cyclin D1 expression and accelerate the proliferation in the human lung adenocarcinoma cells. Our results indicate that exosomes can transfer KIT as a protein to tumor cells, which can affect recipient cell signaling events through receptor-ligand interactions.

Background: Asthma is a common and heterogeneous disease that includes subgroups characterized by type 2 (T2) or type 17 (T17) immune responses for which there is a need to identify the underlying mechanisms and biomarkers in order to develop specific therapies. These subgroups can be defined by airway epithelium gene signatures and the airway epithelium has also been implicated to play a significant role in asthma pathology. Extracellular vesicles (EVs) carry functional biomolecules and participate in cell-to-cell communication in both health and disease, properties that are likely to be involved in airway diseases such as asthma. The aim of this study was to identify stimulus-specific proteins and functionality of bronchial epithelium-derived EVs following stimulation with T2 or T17 cytokines. Methods: EVs from cytokine-stimulated (T2: IL-4 + IL-13 or T17: IL-17A + TNFα) human bronchial epithelial cells cultured at air-liquid interface (HBEC-ALI) were isolated by density cushion centrifugation and size exclusion chromatography and characterized with Western blotting and electron microscopy. Transcriptomic (cells) and proteomic (EVs) profiling was also performed. Results: Our data shows that EVs are secreted and can be isolated from the apical side of HBEC-ALI and that cytokine stimulation increases EV release. Genes upregulated in cells stimulated with T2 or T17 cytokines were increased also on protein level in the EVs. Proteins found in T17-derived EVs were suggested to be involved in pathways related to neutrophil movement which was supported by assessing neutrophil chemotaxis ex vivo. Conclusions: Together, the results suggest that epithelial EVs are involved in airway inflammation and that the EV proteome may be used for discovery of disease-specific mechanisms and signatures which may enable a precision medicine approach to the treatment of asthma.

Regulatory T cells (Tregs) decrease in the adipose tissue upon weight gain, contributing to persistent low-grade inflammation in obesity. We previously showed that adipose tissue Tregs express the adiponectin receptor 1 (AdipoR1); however, the expression in lung Tregs is still unknown. Here, we aimed to determine whether Helios⁺ and Helios⁻ Treg subsets expressed AdipoR1 in the lungs of obese mice and whether different obesity grades affected the expression upon allergic lung inflammation. For diet-induced obesity (DIO), mice were fed a high-fat diet (HFD) for up to 15 weeks (overweight), 21 weeks (obesity), and 26 weeks (morbid obesity). Overweight and morbidly obese mice were sensitized and challenged with ovalbumin (OVA) to induce allergic lung inflammation. The AdipoR1 expression was reduced significantly in the lung Helios⁺ and Helios⁻ Tregs of obese mice compared with lean mice. Airway allergic inflammation showed reduced AdipoR1 expression in lung Foxp3⁺ Tregs. Obesity significantly exacerbated the eosinophilic airway inflammation and reduced the number of Helios⁺ Tregs in lung and adipose tissue in the obesity-associated asthma model. Upon further weight gain, AdipoR1-expressing Tregs in the lungs of allergic mice were increased, whereas AdipoR1-expressing Tregs in adipose tissue were reduced. These data suggest that obesity-associated adipose tissue inflammation may exacerbate allergic inflammation by downregulating the AdipoR1⁺ Tregs in the lungs.

Type 2 innate lymphoid cells (ILC2s) and their adaptive counterpart type 2 T helper (T_H2) cells respond to interleukin-33 (IL-33) by producing IL-5, which is a crucial cytokine for eosinophil development in the bone marrow. The aim of this study was to determine if bone marrow ILC2s, T_H cells, and eosinophils are locally regulated by IL-33 in terms of number and activation upon exposure to the common aeroallergen house dust mite (HDM). Mice that were sensitized and challenged with HDM by intranasal exposures induced eosinophil development in the bone marrow with an initial increase of IL5Rα⁺ eosinophil progenitors, following elevated numbers of mature eosinophils and the induction of airway eosinophilia. Bone marrow ILC2s, T_H2, and eosinophils all responded to HDM challenge by increased IL-33 receptor (ST2) expression. However, only ILC2s, but not T_H cells, revealed increased ST2 expression at the onset of eosinophil development, which significantly correlated with the number of eosinophil progenitors. In summary, our findings suggest that airway allergen challenges with HDM activates IL-33-responsive ILC2s, T_H cells, and eosinophils locally in the bone marrow. Targeting the IL-33/ST2 axis in allergic diseases including asthma may be beneficial by decreasing eosinophil production in the bone marrow.

The incidence, prevalence, and disease prognosis of asthma differ between males and females throughout the life course. However, the underlying mechanisms are not known. Sex hormones might have a potential role in asthma pathogenesis. But most studies on the role of sex hormones in asthma have focused on females, with a paucity of evidence in males. This paper provides a comprehensive review of the state-of-the-art on sex steroids in asthma, focusing on males, covering mechanistic, clinical, and epidemiological studies. Literature search was conducted in PubMed in September 2024. Androgen signaling has a protective role in asthma by reducing airway smooth muscle (ASM) contractility and decreasing airway inflammation. In contrast, estrogens promote type 2 (T2) airway inflammation, but the effect on ASM remain controversial. To date, suggested mechanisms have not fully clarify the underlying pathways through which sex steroids modulate ASM and T2 inflammation in asthma. The balance between androgen and estrogen signaling might also play a role. While epidemiological studies support a protective role for androgens, the evidence on onset of puberty and asthma is inconclusive. Larger longitudinal population samples and stratification based on age and obesity are needed to resolve these questions.

Background: Sex differences have been reported in the incidence, prevalence and severity of asthma. Previous findings from animal models have revealed sex‐related differences in inflammatory pathways that may contribute to asthma pathogenesis, but human studies are limited.Methods: Airway and blood samples (n = 55 and n = 85 respectively) were collected from adult females and males with asthma and healthy subjects. Type 2 innate lymphoid cells (ILC2s), T helper (Th)2 cells and their expression of IL‐33R/ST2 (ST2L) were evaluated by flow cytometry. IL‐13, thymic stromal lymphopoietin (TSLP), IL‐33 and soluble IL‐33R/ST2 (sST2) were measured by ELISA. Let‐7 miRNA expression in bronchial biopsies was determined by qPCR.Results: Females with asthma reported more exacerbations and had a higher number of airway eosinophils compared with males with asthma. Bronchial biopsy expression of Let‐7f, Let‐7g and miR‐98 tended to be higher in males with asthma compared with females and inversely correlated with asthma exacerbations. In contrast, increased levels of IL‐13, TSLP and sST2 were found in females with asthma compared with males.Conclusion: Our study demonstrates different inflammatory signatures between males and females with asthma. Let‐7 miRNAs act as immune modulators by inhibiting the production of IL‐13 and may be an important factor explaining the sex disparity seen in asthma.