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Host-Microbial interactions in Idiopathic Pulmonary Fibrosis

ABSTRACT: Changes in the respiratory microbiome are associated with disease progression in Idiopathic pulmonary fibrosis (IPF). The role of the host response to the respiratory microbiome however remains unknown. The role of this study is to explore the host-microbial interaction in IPF. Network analysis of gene expression data identified two gene modules that strongly associate with a diagnosis of IPF, BAL bacterial burden (determined by 16S quantitative PCR) and specific microbial OTUs, as well as lavage and peripheral blood neutrophilia. Genes within these modules that are involved in the host defence response include NLRC4, PGLYRP1, MMP9, DEFA4. The modules also contain two genes encoding specific antimicrobial peptides (SLPI and CAMP). Many of these particular transcripts were associated with survival and showed longitudinal over expression in subjects experiencing disease progression, further strengthening their relationship with disease. Integrated analysis of the host transcriptome and microbial signatures demonstrates an apparent host response to the presence of an altered or more abundant microbiome. These responses remain elevated on longitudinal follow up, suggesting that the bacterial communities of the lower airways may be acting as persistent stimuli for repetitive alveolar injury in IPF. Sixty patients diagnosed with IPF were prospectively enrolled, together with 20 matched controls. Subjects underwent bronchoalveolar lavage (BAL) and peripheral whole blood was collected into PAXgene tubes for all subjects at baseline. For IPF subjects additional samples were taken at 1, 3, and 6 months and (if alive) a year. Gene expression profiles were generated using Affymetrix Human Gene1.1ST Arrays.

ORGANISM(S): Homo sapiens

PROVIDER: GSE93606 | GEO | 2017/01/14

SECONDARY ACCESSION(S): PRJNA361279

REPOSITORIES: GEO

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Project description:Segmental instillation of lipopolysaccharide (LPS) by bronchoscopy can be used as a model to safely induce transient airway inflammation in the human lung. The LPS challenge model enables investigation of cellular mechanisms involved in pulmonary inflammatory processes as well as pharmacodynamic analysis of investigational drugs for the treatment of respiratory diseases. Aim of this work was to describe the transcriptomic profile of the human segmental LPS challenge model with contextualization to major respiratory diseases. Pre-challenge bronchoalveolar lavage fluid (BAL) and biopsies were sampled from twenty-eight smoking, healthy subjects, followed by segmental LPS challenge and saline control challenge. Twenty-four hours post instillation, BAL and biopsies were collected from the challenged lung segments. Total RNA of cells from BAL and biopsy samples were sequenced for subsequent data analysis. Differential gene expression analysis resulted in 6316 upregulated differentially expressed genes (DEGs) and 241 downregulated DEG in BAL, but only one downregulated DEG in biopsy samples after LPS challenge compared to saline challenge. Upregulated DEG in BAL were related to molecular functions such as “Inflammatory response” or “antimicrobial humoral immune response mediated by antimicrobial peptide”, enriched biological processes such as “chemokine receptor activity”, and upregulated pro-inflammatory pathways such as “Wnt signaling pathway”, “Ras signaling pathway” or “JAK-STAT signaling pathway”. Furthermore, the segmental LPS challenge model resembled aspects of the five most prevalent respiratory diseases chronic obstructive pulmonary disease (COPD), asthma, pneumonia, tuberculosis and lung cancer and featured similarities with acute exacerbations in COPD (AECOPD) and community-acquired pneumonia (CAP). Overall, our study provides extensive information about the transcriptomic profile from BAL cells and mucosal biopsies following LPS challenge in healthy smokers. It expands the knowledge about the LPS challenge model providing potential overlap with respiratory diseases in general and infection-triggered respiratory insults such as AECOPD in particular.

Project description:Introduction: Sarcoidosis is a multisystem immuno-inflammatory disorder of unknown etiology that most commonly involves the lungs. We hypothesized that an unbiased approach to identify pathways activated in alveolar macrophagesâa key immuno-inflammatory cell in the lungâcan shed light on the pathogenesis of this complex disease. Methods: We recruited 15 patients with various stages of sarcoidosis and 12 healthy controls. All subjects underwent bronchoscopy with lavage. For each subject, total RNA was extracted from bronchoalveolar (BAL) cells and hybridized to an Affymetrix GeneChip Human Genome U133A 2.0 microarray. Rigorous statistical methods were applied to identify differential gene expression between subjects with sarcoidosis vs. controls. To better elucidate pathways differentially activated between these groups, we applied gene set enrichment analysis (GSEA) to the transcriptional profiles of BAL cells. We used false discovery rate (FDR) < 0.01 to designate significant enrichment. Results: Sarcoid patients were either non-smokers or ex-smokers, all had lung involvement and only 2 were on systemic prednisone. Healthy controls were all non-smokers. Comparison of BAL cell gene expression between sarcoidosis and healthy subjects revealed over 1200 differentially expressed genes at an FDR cutoff < 0.01. Several previously described immune mediators, such as interferon gamma, were up-regulated in the sarcoidosis subjects. Since genes often exert their influence through functionally coherent modules, we performed GSEA based on global expression profiles of alveolar macrophages between the subject groups. We identified more than 200 gene sets enriched in patients with sarcoidosis whereas very few pathways were over-represented in the healthy controls. Many of the sarcoidosis-associated pathways mapped to inflammatory and immune-related processes including T-cell signaling, graft vs. host disease, IL-12, IL-23, and IL-17 pathways, and oxidative phosphorylation. However, we also found and confirmed significant alteration in Proteasome-related pathways. Conclusions: BAL cells in sarcoidosis are characterized by enrichment of distinct transcriptional networks involved in immuno-inflammatory and proteasomal processes. Our findings add to the growing evidence implicating airspace resident cells in the pathogenesis of sarcoidoisis and identify specific pathways whose activation may modulate disease progression. Total RNA from BAL cells of 15 subjects with sarcoidosis and 12 healthy controls was hybridized to 27 Affymetrix Genechip Human U133A 2.0 microarrays

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Host-Microbial interactions in Idiopathic Pulmonary Fibrosis

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