Search

Combined exposure to the alarmins TSLP, IL-33 and IL-25 enhances mast cell-dependent contractions of human bronchi Keywords: airway hyperresponsiveness; anti-IgE; asthma; histamine; IL-33; prostaglandin D2; TSLP EN airway hyperresponsiveness anti-IgE asthma histamine IL-33 prostaglandin D2 TSLP 1062 1066 5 10/09/23 20231001 NES 231001 Key Messages Combined pretreatment with TSLP, IL-33 and IL-25 (epithelial alarmins) enhanced IgE-triggered contraction in isolated human bronchi. The release of histamine in response to IgE-mediated stimulation increased only in the alarmin mix pretreated group, indicating that, as shown for PGD SB 2, sb the alarmin mix enhanced the IgE-triggered release of histamine, presumably by increasing mast cell reactivity. Airway hyperresponsiveness, asthma, histamine, IL-33, anti-IgE, TSLP, prostaglandin D2. [Extracted from the article]

Background: Genome‐wide association studies have identified associations of the single nucleotide polymorphism rs1837253 in the thymic stromal lymphopoietin (TSLP) gene with asthma, allergic disease and eosinophilia. The TSLP gene encodes two isoforms, long and short, and previous studies have indicated functional differences between these two isoforms. Objective: We investigated the expression of these TSLP isoforms in response to a pro‐inflammatory signal, and the role of the rs1837253 genotype in gene isoform regulation. Methods: We cultured nasal epithelial cells of asthmatic and non‐asthmatic subjects and evaluated poly(I:C)‐induced TSLP protein secretion using multiplex protein assays and gene expression profiles of the TSLP isoforms, and related genes using real‐time qPCR. We correlated these profiles with rs1837253 genotype. Results: Asthmatic nasal epithelial cells exhibited increased TSLP protein secretion compared with nasal epithelial cells from healthy controls. The long TSLP isoform was more responsive to poly(I:C) stimulation. Additionally, the minor T allele of rs1837253 was less inducible than the major C allele, suggesting differential regulation; this may explain the "protective" effects of the T allele in asthma. Conclusion: Our results provide important insights into the differential regulation and function of TSLP isoforms, including the role of TSLP rs1837253 polymorphisms in allergic inflammatory processes. Clinical relevance: The key finding on the influence of TSLP genetic variation on disease expression/endotype could provide basis for investigation into targeted biologics for anti‐TSLP therapies. [ABSTRACT FROM AUTHOR]

Summary: Background: Thymic stromal lymphopoietin (TSLP) is a regulator of mast cell‐mediated allergic inflammatory reactions, but the manner in which TSLP contributes to allergic rhinitis (AR) remains unclear. Objective: Here, we sought to determine that TSLP plays a crucial role in AR by interacting with Src‐type tyrosine kinase p56lck and STAT6 and promoting mast cells degranulation. Methods: The effects of TSLP on mast cell degranulation and AR were analysed in human mast cell line (HMC‐1 cells), ovalbumin (OVA)‐induced AR animal model, and human subjects. Small interfering RNA experiments were performed in HMC‐1 cells and OVA‐induced AR model. Immune responses were analysed by enzyme‐linked immunosorbent assay, Western blotting, immunoprecipitation, and histological studies. Results: Thymic stromal lymphopoietin levels and mast cell‐derived p56lck activation were elevated in human subjects with AR, and in AR mice, exogenous TSLP accelerated TH2‐allergic inflammatory reactions by up‐regulating p56lck and STAT6. On the other hand, depletion of TSLP, p56lck, and STAT6 ameliorated clinical symptoms in AR mice. The selective inhibitor of p56lck, damnacanthal, inhibits AR reactions. Conclusion: Collectively, these observations suggest a role for TSLP/p56lck/STAT6 in AR and offer insight into potential therapeutic strategies. [ABSTRACT FROM AUTHOR]

Background Airway hyperresponsiveness (AHR) to inhaled mannitol is associated with indirect markers of mast cell activation and eosinophilic airway inflammation. It is unknown how AHR to mannitol relates to mast cell phenotype, mast cell function and measures of eosinophilic inflammation in airway tissue. We compared the number and phenotype of mast cells, mRNA expression of mast cell-associated genes and number of eosinophils in airway tissue of subjects with asthma and healthy controls in relation to AHR to mannitol. Methods Airway hyperresponsiveness to inhaled mannitol was measured in 23 non-smoking, corticosteroid-free asthmatic individuals and 10 healthy controls. Mast cells and eosinophils were identified in mucosal biopsies from all participants. Mast cells were divided into phenotypes based on the presence of chymase. mRNA expression of mast cell-associated genes was measured by real-time PCR. Results The proportion of submucosal MCTC was higher in asthmatic individuals with AHR to mannitol compared with asthmatic individuals without AHR (median: 40.3% vs. 18.7%, P = 0.03). Increased submucosal MCTC numbers were associated with increased levels of mRNA for thymic stromal lymphopoietin (TSLP) and CPA3 in asthmatics. Reactivity to mannitol correlated significantly with eosinophils in submucosa ( r(s): 0.56, P = 0.01). Conclusion Airway hyperresponsiveness to inhaled mannitol is associated with an altered submucosal mast cell profile in asthmatic individuals. This mast cell profile is associated with increased levels of TSLP and CPA3. The degree of AHR to mannitol is correlated with the degree of eosinophilic inflammation in the airway submucosa. [ABSTRACT FROM AUTHOR]

Background Inhaled peptide challenge has been shown to induce T cell-mediated, isolated late asthmatic reaction ( LAR), characterized by recruitment of CD4+ T cells and increased levels of thymus and activation-regulated chemokine ( TARC; CCL17). Epithelial-derived thymic stromal lymphopoietin ( TSLP) has been shown to modulate dendritic cell function to promote TH2 responses via CCL17 production. Objectives To elucidate the mechanisms involved in allergen-specific T cell-induced LAR and recruitment of CD4+ T cells by examining the effects of T cell-derived factors on the induction of TSLP in primary bronchial epithelial cells ( PBEC). Methods PBEC grown at air-liquid interface from healthy individuals and patients with asthma were stimulated with double-stranded RNA (ds RNA) or supernatants from activated allergen-specific T cells. TSLP was measured in PBEC culture supernatants. Neutralizing antibodies and signalling inhibitors were used to examine the mechanisms responsible for the induction of epithelial-derived TSLP. The functional activity of PBEC-derived TSLP was measured using a bioassay involving the induction of CCL17 production from monocyte-derived dendritic cells (mo DC). Results Both ds RNA and allergen-specific T cells induced enhanced TSLP secretion from asthmatic PBEC compared to healthy PBEC. Activated PBEC culture supernatant induced TSLP-dependent CCL17 production from mo DC in a manner related to clinical asthmatic status. IL-1β, IL-6, and CXCL8, rather than TH2 cytokines ( IL-4/5/13), appeared to be the principle mediators of allergen-specific T cell-dependent induction of epithelial-derived TSLP, which was regulated by the MEK, MAPK, and NFκB pathways. Conclusion and Clinical Relevance Our data reveal a novel effect of allergen-specific T cells as a positive regulator of TSLP production by epithelial cells, suggesting T cell-airway epithelium interactions that may lead to maintenance and amplification of allergic inflammation. TSLP is currently a candidate for therapeutic intervention in asthma, but the factors that drive TSLP expression ( T cell-derived factors) may be equally relevant in the treatment of allergic inflammation. [ABSTRACT FROM AUTHOR]

Background Mouse models of atopic march suggest that systemic, skin-derived thymic stromal lymphopoietin ( TSLP) mediates progression from eczema to asthma. Objective We investigated whether circulating TSLP is associated with eczema, allergic sensitization, or recurrent wheezing in young children. Methods A prospective analysis of the relationship between plasma levels of TSLP to allergic sensitization and recurrent wheezing was conducted in the birth cohort from the Urban Environment and Childhood Asthma ( URECA) study. Plasma TSLP levels were measured at 1, 2, and 3 years of age and analysed for correlation with clinical parameters in each of the three years. Only those children with consecutive samples for all three years were included in this analysis. Results We detected TSLP in 33% of 236 children for whom plasma samples were available for all three years. Overall, a consistently significant association was not found between TSLP and eczema or allergic sensitization. With regard to recurrent wheezing, children with detectable TSLP at one year of age were significantly less likely to experience recurrent wheezing by 3 years compared with those children without detectable TSLP, but this was only seen in children without aeroallergen sensitization at 3 years ( P < 0.01). Conclusions and Clinical Relevance Contrary to our expectations, circulating TSLP was not significantly associated with eczema, allergen sensitization, or recurrent wheezing during the first three years of life. Early presence of circulating TSLP was significantly associated with reduced incidence of recurrent wheeze in those children not sensitized to aeroallergen. These findings suggest a possible underlying distinction between pathogenesis of developing atopic vs. non-atopic recurrent wheeze. [ABSTRACT FROM AUTHOR]

Background Myeloid dendritic cells ( mDCs) and costimulatory molecules such as ICOSL/B7H2 play a pivotal role in murine experimental asthma, while little is known in human allergic disease. The aim of this study was to characterize the phenotype and ICOSL expression of mDCs from allergic rhinitis patients (AR) and their functional correlates on mDC regulation of T cell responses. Methods Human blood myeloid, CD1c+ DCs were isolated from AR or healthy controls. Expression of costimulatory molecules inducible costimulatory ligand (ICOSL) and programmed death ligand 1 (PD-L1) was analysed in blood mDCs by flow cytometry and in nasal tissue biopsies by dual immunostaining. Blood mDCs were cocultured with (allogeneic) CD4+ T cells before immunoassays for cytokine responses. Results mDCs from AR patients expressed a lower level of ICOSL, in both blood and nasal tissue. mDCs from AR were constitutively primed to induce Th2 cytokines and TNF in allogeneic CD4+ T cells, while no difference was observed for IFN-γ or IL-10. Production of IL-10 and IL-12 did not differ between AR and control mDCs. Blockade of ICOSL in control DCs up-regulated IL-13 but not IFN-γ in cocultures with T cells, while PD-L1 blockade up-regulated both IL-13 and IFN-γ. Conclusions Our data show that mDCs from patients with AR display impaired expression of ICOSL, and this defect licenses mDCs to promote aberrant IL-13- and IL-5-producing Th2 cell responses. [ABSTRACT FROM AUTHOR]

Background Human thymic stromal lymphopoietin (TSLP) is expressed in the human asthmatic lung and activates dendritic cells (DCs) to strongly induce proallergic T-helper type 2 (Th2) cell responses, suggesting that TSLP plays a critical role in the pathophysiology of human asthma. Th2 cells are predominantly involved in mild asthma, whereas a mixture of Th1 and Th2 cells with neutrophilic inflammation, probably induced by Th17, affects more severe asthmatic disease. Exacerbation of asthmatic inflammation is often triggered by airway-targeting RNA viral infection; virus-derived double-stranded RNA, Toll-like receptor (TLR)3 ligand, activates bronchial epithelial cells to produce pro-inflammatory mediators, including TSLP. Objective Because TSLPR-expressing DCs express TLR3, we examined how the relationship between TSLP and TLR3 ligand stimulation influences DC activation. Methods CD11c+DCs purified from adult peripheral blood were cultured in TLR ligands containing media with or without TSLP and then co-cultured with allogeneic naïve CD4+T cells. Results CD11c+ DCs responded to a combination of TSLP and TLR3 ligand, poly(I : C), to up-regulate expression of the functional TSLP receptor and TLR3. Although TSLP alone did not induce IL-23 production by DCs, poly(I : C) alone primed DCs for the production of IL-23, and a combination of TSLP and poly(I : C) primed DCs for further production of IL-23. The addition of poly(I : C) did not inhibit TSLP-activated DCs to prime naïve CD4+ T cells to differentiate into inflammatory Th2 cells. Furthermore, DCs activated by a combination of TSLP and poly(I : C) primed more naïve CD4+ T cells to differentiate into Th17-cytokine–producing cells with a central memory T cell phenotype compared with DCs activated by poly(I : C) alone. Conclusions These results suggest that through DC activation, human TSLP and TLR3 ligands promote differentiation of Th17 cells with the central memory T cell phenotype under Th2-polarizing conditions. [ABSTRACT FROM AUTHOR]