Immunophenotyping of Acute Inflammatory Exacerbations of Lung Injury Driven by Mutant Surfactant Protein-C: A Role for Inflammatory Eosinophils
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ABSTRACT: Immunophenotyping of Acute Inflammatory Exacerbations of Lung Injury Driven by Mutant Surfactant Protein-C: A Role for Inflammatory Eosinophils
Project description:Acute inflammatory exacerbations (AIEs) represent immune-driven deteriorations of many chronic lung conditions, including COPD, asthma, and pulmonary fibrosis (PF). The first line of therapy is represented by broad-spectrum immunomodulation. Among the several inflammatory populations mobilizing during AIEs, eosinophils have been identified as promising indicators of an active inflammatory exacerbation. To better study the eosinophil-parenchymal crosstalk during AIE-PF, this work leverages a clinically relevant model of inflammatory exacerbations triggered by mutation in the alveolar epithelial type 2 cell Surfactant Protein-C gene [SP-CI73T]. Unbiased single-cell sequencing analysis of controls and SP-CI73T mutants at a time coordinated with peak eosinophilia (14 d) defined heightened inflammatory activation, chemotaxis, and survival signaling (IL-6, IL-4/13, STAT3, Glucocorticoid Receptor, mTOR, and MYC) in eosinophils. To study the impact of eosinophils in inflammatory exacerbations, the SP-CI73T line was crossed with eosinophil lineage deficient mice (GATA1Δdbl, SP-CI73TGATA1KO). Time course analysis (7-42 d) demonstrated improved lung histology, survival, and reduced inflammation in SP-CI73TGATA1KO cohorts. Spectral flow cytometry of tissue digests confirmed eosinophil depletion in GATA1KO mice and the absence of a compensatory shift in neutrophils and immature monocyte recruitment. Eosinophil deletion was seen to boost accumulation of total monocyte-derived macrophages, 14 d post-injury, while declines in CD3+CD4+ lymphocyte abundance observed during SP-CI73T-induced injury were limited in SP-CI73TGATA1KO mice. Histochemical analysis 14 d post-injury revealed atypical inflammatory cell activation in SP-CI73TGATA1KO mice, with reduced numbers of Arg-1+ and iNOS+ cells, but increases in mcp1 and tgfb1 mRNA expression in BAL cells and tissue. To study corticosteroid efficacy in highly eosinophilic exacerbations, SP-CI73T mice received dexamethasone (1 mg/kg daily, i.p) starting 5 d post-induction. Dexamethasone successfully reduced total and eosinophil (CD11b+SigF+CD11c-) counts at 14 d and was linked to reduced evidence of structural damage and perivascular infiltrate. Together, these results illustrate the deleterious role of eosinophils in inflammatory events preceding lung fibrosis and demonstrate the efficacy of corticosteroid treatment in highly eosinophilic exacerbations induced by mutant SP-CI73T.
Project description:Acute inflammatory exacerbations (AIEs) represent immune-driven deteriorations of many chronic lung conditions, including COPD, asthma, and pulmonary fibrosis (PF). The first line of therapy is represented by broad-spectrum immunomodulation. Among the several inflammatory populations mobilizing during AIEs, eosinophils have been identified as promising indicators of an active inflammatory exacerbation. To better study the eosinophil-parenchymal crosstalk during AIE-PF, this work leverages a clinically relevant model of inflammatory exacerbations triggered by inducible expression of a mutation in the alveolar epithelial type 2 cell Surfactant Protein-C gene [SP-CI73T]. Unbiased single-cell sequencing analysis of controls and SP-CI73T mutants at a time coordinated with peak eosinophilia (14 days) defined heightened inflammatory activation, chemotaxis, and survival signaling (IL-6, IL-4/13, STAT3, Glucocorticoid Receptor, mTOR, and MYC) in eosinophils. To study the impact of eosinophils in inflammatory exacerbations, the SP-CI73T line was crossed with eosinophil lineage deficient mice (GATA1Δdbl) to produce the SP-CI73TGATA1KO line. Time course analysis (7-42 days) demonstrated improved lung histology, survival, and reduced inflammation in SP-CI73TGATA1KO cohorts. Spectral flow cytometry of tissue digests confirmed eosinophil depletion in GATA1KO mice and the absence of a compensatory shift in neutrophils and immature monocyte recruitment. Eosinophil deletion resulted in progressive monocyte-derived macrophage accumulation (14 days post-injury), combined with declines in CD3+CD4+ lymphocyte and B220+ B cell abundance. Histochemical analysis revealed atypical inflammatory cell activation in SP-CI73TGATA1KO mice, with reduced numbers of Arg-1+ and iNOS+ cells, but increases in tgfb1 mRNA expression in bronchoalveolar lavage cells and tissue. Dexamethasone treatment (1 mg/kg daily, i.p.) was utilized to investigate corticosteroid efficacy in highly eosinophilic exacerbations induced by mutant SP-CI73T. Dexamethasone successfully reduced total and eosinophil (CD11b+SigF+CD11c-) counts at 14 days and was linked to reduced evidence of structural damage and perivascular infiltrate. Together, these results illustrate the deleterious role of eosinophils in inflammatory events preceding lung fibrosis and demonstrate the efficacy of corticosteroid treatment in highly eosinophilic exacerbations induced by mutant SP-CI73T.
Project description:Asthma exacerbations are associated with subsequent deficits in lung function. Here, we tested the hypothesis that a specific pattern of inflammatory responses during acute exacerbations may be associated with susceptibility to chronic airway obstruction.
Project description:Triggering Receptor Expressed on Myeloid cells 1 (TREM-1) an innate receptor that canonically amplifies inflammatory signaling in neutrophils and monocytes, plays a central role in regulating lung inflammation. Utilizing a murine model of asthma, flow cytometry revealed TREM-1+ eosinophils in the lung tissue and airway during allergic airway inflammation. TREM-1 expression was restricted to recruited, inflammatory eosinophils. Expression was induced on bone marrow derived eosinophils by incubation with IL-33, LPS, or GM-CSF. Compared to TREM-1- airway eosinophils, TREM-1+ eosinophils were enriched for pro-inflammatory gene sets including migration, respiratory burst, and cytokine production. Unexpectedly, eosinophil-specific ablation of TREM-1 increased airway IL-5 and lung tissue eosinophil accumulation. Further investigation of transcriptional data revealed apoptosis related gene sets were enriched in TREM-1+ eosinophils. Annexin V staining demonstrated higher rates of apoptosis among TREM-1+ eosinophils compared to TREM-1- eosinophils in the inflammatory airway. In vitro, Trem1/3-/- eosinophils were protected from apoptosis. Finally, inhibition of reactive oxygen species production with diphenyleneiodonium protected WT bone marrow derived eosinophils from apoptosis more than Trem1/3-/- eosinophils, suggesting that superoxide accounted for more apoptosis in WT cells. These data demonstrate protein level expression of TREM-1 by eosinophils for the first time, define a population of TREM-1+ inflammatory eosinophils, and reveal that eosinophil TREM-1 restricts key features of type 2 lung inflammation.
Project description:While biologic therapies targeting type 2 (T2) inflammation reduce acute exacerbation rates in children with asthma and T2 inflammation, exacerbations still occur, and the underlying molecular mechanisms are poorly defined. We aimed to identify multiple distinct molecular mechanisms implicated in asthma exacerbations by characterizing respiratory illnesses among urban children with eosinophilic asthma enrolled in a clinical trial comparing treatment with mepolizumab versus placebo
Project description:Eosinophilia is associated with various persisting inflammatory diseases and often coincides with chronic fungal infections or fungal allergy as in case of allergic bronchopulmonary aspergillosis (ABPA). However, the interactions between eosinophils and fungal pathogen leading to release of inflammatory mediators from eosinophils are poorly understood. Therefore, we established a co-culture system of mouse bone marrow derived eosinophils (BMDE) with Aspergillus fumigatus (Af) that we used in part to analyse transcriptional regulation induced by Af.
Project description:Acute inflammatory exacerbations (AIE) represent precipitous deteriorations of a number of chronic lung conditions, including pulmonary fibrosis (PF), chronic obstructive pulmonary disease and asthma. AIEs are marked by diffuse and persistent polycellular alveolitis that profoundly accelerate lung function decline and mortality. In particular, excess monocyte mobilization during AIE and their persistence in the lung have been suggested to be linked to poor disease outcome. We have developed a mutant model of pulmonary fibrosis leveraging the PF-linked missense isoleucine to threonine substitution at position 73 [I73T] in the alveolar type-2 cell-restricted Surfactant Protein-C [SP-C] gene [SFTPC]. With this toolbox at hand, the present work investigates the dynamics of resident alveolar macrophages and peripheral monocytes during the initiation and progression of AIE-PF. FACS analysis of SigF+CD11b- alveolar macrophages and Ly6Chi monocytes isolated 3 d and 14 d after SP-CI73T injury and performed RNA sequencing. Pathway and gene expression analysis revelaed dynamic transcriptional changes associated with “Innate Immunity’ and ‘Extracellular Matrix Organization’ signaling. Supported by previous pharmacological evidence, genetic ablation of CCR2+ monocytes (SP-CI73TCCR2KO) resulted in improved lung histology, mouse survival, and reduced inflammation compared to SP-CI73TCCR2WT cohorts. Immunohistochemical and in situ hybridization analysis revealed comparable levels of tgfb1 mRNA expression localized primarily parenchymal cells found nearby foci of injury. Our results also confirmed reduced inflammatory activation (iNOS, Arg1) in SP-CI73TCCR2KO lungs as well as partial colocalization of tgfb1 mRNA expression in Arg1+ cells. These results provide a detailed picture on the role of resident macrophages and recruited monocytes in the context of AIE-PF driven by alveolar epithelial dysfunction.
Project description:Investigation of gene expression profiles among patients with COPD frequent exacerbations and to find gene targets as predictors of exacerbations COPD patient samples analysed by microarray, followed by PCR testing to identify gene predictors
Project description:Eosinophils are elusive cells involved in allergic inflammation. Herein, we profiled 586 human eosinophils from the circulation and an allergic inflammatory site, the esophagus, of patients with eosinophilic esophagitis by Seq-Well–based single-cell RNA sequencing. The esophageal eosinophils were composed of a population of activated eosinophils (enriched in 659 genes compared with peripheral blood-associated eosinophils) and a small population of eosinophils resembling peripheral blood eosinophils (enriched in 62 genes compared with esophageal eosinophils). Esophageal eosinophils expressed genes involved in sensing and responding to diverse stimuli, most notably interferon-Ɣ(IFN-Ɣ), interleukin 10 (IL-10), histamine and leukotrienes, and succinate metabolite signaling. Esophageal eosinophils were most distinguished from other esophageal populations by gene expression of the receptors CCR3, HRH4, SUCNR1, and VSTM1; transcription factors CEBPE, OLIG1, and OLIG2; protease PRSS33; and hallmark eosinophil gene CLC. A web of bidirectional eosinophil interactions with other myeloid cells, T cells, fibroblasts, and the epithelium and vasculature was derived. Comparing esophageal eosinophils and mast cells revealed that esophageal eosinophils expressed genes involved in DAP12 interactions, IgG receptor-triggered events, immunoregulation, and IL-10 signaling, whereas esophageal mast cells expressed genes involved in arachidonic acid metabolism and response to unfolded proteins. These findings indicate that esophageal eosinophils exist as two populations, a minority population resembling blood eosinophils and the other population characterized by high de novo transcription of diverse sensing receptors and inflammatory mediators readying them to intersect with diverse cell types.
Project description:The amount of pulmonary surfactant within type II cells and in the alveolar space, referred to as surfactant pool sizes, are tightly regulated. The molecular pathways that sense and regulate surfactant pool size within the alveolus have not been identified and constitute a fundamental knowledge gap in the field. Our data show that mice with a germline mutation in the orphan G-protein-coupled receptor, GPR116, have a 30-fold accumulation of surfactant phospholipids that causes respiratory distress in adult animals. This phenotype is associated with increased surfactant secretion and induction of the purinergic receptor P2RY2 in young animals, and lipid-laden macrophages and alveolar destruction in older animals. We further demonstrate that GPR116 mRNA expression is developmentally regulated in the murine lung with peak expression at birth when surfactant pool sizes are maximal. Within the lung, GPR116 protein expression is restricted to the apical plasma membrane of alveolar type I and type II epithelial cells.