YTHDF1-CLOCK axis contributes to pathogenesis of allergic airway inflammation through LLPS [m6A-seq]
Ontology highlight
ABSTRACT: N6-methyladenosine (m6A) modification has been implicated in many cell processes and diseases. YTHDF1, a translation-facilitating m6A reader, is not previously shown to be related to allergic airway inflammation. Here, we report that YTHDF1 is highly expressed in allergic airway epithelial cells (AECs) and asthmatic patients, and influences proinflammatory responses. CLOCK, a subunit of the circadian clock pathway, is the direct target of YTHDF1. YTHDF1 augments CLOCK translation in an m6A-dependent manner. Allergens enhance the liquid‒liquid phase separation (LLPS) of YTHDF1 and drive the formation of a complex comprising dimeric YTHDF1 and CLOCK mRNA, which is distributed to stress granules (SGs). Moreover, YTHDF1 strongly activates NLRP3 inflammasome production and IL-1β secretion, leading to airway inflammatory responses, but these phenotypes are abolished by deleting CLOCK. These findings demonstrate that YTHDF1 is an important regulator of asthmatic airway inflammation, suggesting a potential therapeutic target for allergic airway inflammation.
Project description:N6-methyladenosine (m6A) modification has been implicated in many cell processes and diseases. YTHDF1, a translation-facilitating m6A reader, is not previously shown to be related to allergic airway inflammation. Here, we report that YTHDF1 is highly expressed in allergic airway epithelial cells (AECs) and asthmatic patients, and influences proinflammatory responses. CLOCK, a subunit of the circadian clock pathway, is the direct target of YTHDF1. YTHDF1 augments CLOCK translation in an m6A-dependent manner. Allergens enhance the liquid‒liquid phase separation (LLPS) of YTHDF1 and drive the formation of a complex comprising dimeric YTHDF1 and CLOCK mRNA, which is distributed to stress granules (SGs). Moreover, YTHDF1 strongly activates NLRP3 inflammasome production and IL-1β secretion, leading to airway inflammatory responses, but these phenotypes are abolished by deleting CLOCK. These findings demonstrate that YTHDF1 is an important regulator of asthmatic airway inflammation, suggesting a potential therapeutic target for allergic airway inflammation.
Project description:N6-methyladenosine (m6A) is the most abundant internal messenger (mRNA) modification in mammalian mRNA. This modification is reversible and non-stoichiometric, which potentially adds an additional layer of variety and dynamic control of mRNA metabolism. The m6A-modified mRNA can be selectively recognized by the YTH family “reader” proteins. The preferential binding of m6A-containing mRNA by YTHDF2 is known to reduce the stability of the target transcripts; however, the exact effects of m6A on translation has yet to be elucidated. Here we show that another m6A reader protein, YTHDF1, promotes ribosome loading of its target transcripts. YTHDF1 forms a complex with translation initiation factors to elevate the translation efficiency of its bound mRNA. In a unified mechanism of translation control through m6A, the YTHDF2-mediated decay controls the lifetime of target transcripts; whereas, the YTHDF1-based translation promotion increases the translation efficiency to ensure effective protein production from relatively short-lived transcripts that are marked by m6A. PAR-CLIP and RIP was used to identify YTHDF1 binding sites followed by ribosome profling and RNA seq to assess the consequences of YTHDF1 siRNA knock-down
Project description:DNA methylation profiling of airway epithelial cells (AECs) and peripheral blood mononuclear cells (PBMCs) from normal, atopic and asthmatic subjects. The Illumina GoldenGate Methylation Cancer Panel I was used to obtain DNA methylation profiles across approximately 1505 CpGs in AECs and PBMCs. Samples included 7 healthy, 9 atopic, 4 atopic asthmatic and 5 non-atopic asthmatic subjects. Please note that only some of the samples are matched (i.e. AECs and PBMCs from the same individual) due to DNA quality or sample collection (i.e. only one sample (AEC or PBMC) was collected from the patient). Bisulphite converted DNA from the 41 samples were hybridised to the Illumina GoldenGate Methylation Beadchip
Project description:The airway epithelium forms the interface between the inhaled environment and the lung. The airway epithelium is dysfunctional in asthma and epigenetic mechanisms are considered a contributory factor. We hypothesised that the DNA methylation profiles of cultured primary airway epithelial cells (AECs) would differ between cells isolated from individuals with asthma (n=17) versus those without asthma (n=16). AECs were isolated from patients by two different isolation techniques; pronase digestion (9 non-asthmatic, 8 asthmatic) and bronchial brushings (7 non-asthmatic and 9 asthmatic). DNA methylation was assessed using an Illumina Infinium HumanMethylation450 BeadChip array. DNA methylation of AECs clustered by isolation technique and linear regression identified 111 CpG sites differentially methylated between isolation techniques in healthy individuals. As a consequence, the effect of asthmatic status on DNA methylation was assessed within AEC samples isolated using the same technique. In pronase isolated AECs, 15 DNA regions were differentially methylated between asthmatics and non-asthmatics. In bronchial brush isolated AECs, 849 differentially methylated DNA regions were identified with no overlap to pronase regions. In conclusion, regardless of cell isolation technique, differential DNA methylation was associated with asthmatic status in AECs, providing further evidence for aberrant DNA methylation as a signature of epithelial dysfunction in asthma.
Project description:DNA methylation profiling of airway epithelial cells (AECs) and peripheral blood mononuclear cells (PBMCs) from normal, atopic and asthmatic subjects. The Illumina GoldenGate Methylation Cancer Panel I was used to obtain DNA methylation profiles across approximately 1505 CpGs in AECs and PBMCs. Samples included 7 healthy, 9 atopic, 4 atopic asthmatic and 5 non-atopic asthmatic subjects. Please note that only some of the samples are matched (i.e. AECs and PBMCs from the same individual) due to DNA quality or sample collection (i.e. only one sample (AEC or PBMC) was collected from the patient).
Project description:Rationale: Mast cells (MCs) within the airway epithelium in asthma are closely related to airway dysfunction, but crosstalk between airway epithelial cells (AECs) and MCs in asthma remains incompletely understood. Human rhinovirus (HRV) infections are key triggers for asthma progression and AECs from individuals with asthma may have dysregulated anti-viral responses. Objectives: We utilize primary phenotyped AECs in an ex vivo coculture model system to examine crosstalk between AECs and MCs following epithelial HRV infection. Methods: Primary AECs were obtained from children with asthma (n=11) and healthy children (n=10), differentiated at air-liquid interface, and cultured in the presence of laboratory of allergic diseases-2 (LAD2) MCs. AECs were infected with HRV serogroup A 16 (HRV16) for 48 hours. RNA isolated from both AECs and MCs underwent RNA-sequencing (RNAseq) analysis. Direct effects of epithelial-derived interferons on LAD2 MCs were examined by qPCR. Results: MCs increased expression of pro-inflammatory and anti-viral genes in AECs. AECs demonstrated a robust antiviral response following HRV16 infection that resulted in significant changes in MC gene expression, including upregulation of genes involved in anti-viral responses, leukocyte activation, and type-2 (T2) inflammation. Subsequent ex vivo modeling demonstrated that IFN-β induces MC IL13 expression. The effects of AEC phenotype were small relative to the effects of viral infection and the presence of MCs. Conclusions: There is significant crosstalk between AECs and MCs, which are present in the epithelium in asthma. Epithelial-derived interferons not only play a role in viral suppression, but further alter MC immune responses including specific T2 genes.
Project description:Background: A specific subset of regulatory IL-10 producing B cells has been extensively studied in autoimmune and inflammatory pathologies. These cells are able to constrain exacerbated inflammation by inhibiting T cell mediated responses and maturation of antigen presenting cells. In allergic diseases, observations that increase of regulatory B cells is necessary for allergen tolerance suggest that development of allergic asthma would be associated with a defect in the regulatory B cells compartment. Objective: We sought to (i) characterize regulatory IL-10+ regulatory B cell subset in Balb/c mice by microarray and flow cytometry and (ii) investigate their regulatory capacity in vivo in a house dust mite model of allergic asthma. Results: We identified an IL-10 producing B cells subset able to control T cell proliferation in vitro in both control and asthmatic mice. This subset is decreased in allergic mice. IL-10+ Breg cells express high levels of CD9 and upregulate CD70 and CD73 after activation. Expression of CD9 allows identifying more than 50% of Bregs. Interestingly CD9+ B cells inhibit TH2-TH17 allergic airway inflammation in vivo after adoptive transfer in an IL-10 dependent manner. Conclusions: Herein, we demonstrate that induction of allergic asthma dampens the generation of Bregs contributing to exacerbated airway inflammation. We identified a distinct CD9+ Breg-cell population decreased in lung of HDM mice and able to control asthma and allergic airway inflammation by producing IL-10 after adoptive transfer. This study points B cells as an interesting therapeutic target in allergic asthma. IL-10+ B cells (n=3) and 3 IL-10- B cells (n=3) in control mice + IL-10+ B cells (n=3) and 3 IL-10- B cells (n=3) from asthmatic allergic (HDM) mice
Project description:Nociceptor neurons play a crucial role in maintaining the body’s homeostasis by detecting and responding to potential dangers in the environment. However, this function can be detrimental during allergic reactions, since vagal nociceptors can contribute to immune cell infiltration, bronchial hypersensitivity, and mucus imbalance, in addition to causing pain and coughing. Despite this, the specific mechanisms by which nociceptors acquire pro-inflammatory characteristics during allergic reactions are not yet fully understood. In this study, we aimed to investigate the molecular profile of airway nociceptor neurons during allergic airway inflammation and identify the signals driving such reprogramming. Using retrograde tracing and lineage reporting, we identified a unique class of inflammatory vagal nociceptor neurons that exclusively innervate the airways. In the ovalbumin mouse model of airway inflammation, these neurons undergo significant reprogramming characterized by the upregulation of the NPY receptor Npy1r. A screening of cytokines and neurotrophins revealed that IL-1β, IL-13 and BDNF drive part of this reprogramming. IL-13 triggered Npy1r overexpression in nociceptors via the JAK/STAT6 pathway. In parallel, sympathetic neurons and macrophages release NPY in the bronchoalveolar fluid of asthmatic mice, which limits the excitability of nociceptor neurons. Single-cell RNA sequencing of lung immune cells has revealed that a cell-specific knockout of Npy1r in nociceptor neurons in asthmatic mice leads to an increase in airway inflammation mediated by T cells. Opposite findings were observed in asthmatic mice in which nociceptor neurons were chemically ablated. In summary, allergic airway inflammation reprograms airway nociceptor neurons to acquire a pro-inflammatory phenotype, while a compensatory mechanism involving NPY1R limits nociceptor neurons’ activity.