Project description:Background: When exposed to specific stimuli, macrophages exhibit distinct activation programs, M1 and M2 polarization, that define macrophage function as inflammatory/immune effectors or anti-inflammatory/tissue remodeling cells, respectively. Due to their position on the lung epithelial surface, alveolar macrophages (AM) directly interact with environmental stimuli such as cigarette smoke, the major risk factor for the development of chronic obstructive pulmonary disease (COPD). Based on the current paradigm that, in response to smoking, AM contribute to both inflammatory and tissue remodeling processes in the lung relevant to the pathogenesis of COPD, we hypothesized that chronic exposure to cigarette smoking activates both the M1 and M2 polarization programs in AM. Methods and Findings: To assess this hypothesis, global transcriptional profiling with TaqMan confirmation and flow cytometry analysis was carried out on AM obtained by bronchoalveolar lavage of 24 healthy nonsmokers, 34 healthy smokers and 12 smokers with COPD to assess the expression of 41 M1 genes and 32 M2 genes in each group. Contrary to our expectations, while there was up-regulation of some genes typical for M2-related phenotypes, AM of healthy smokers exhibited substantial suppression of M1-related inflammatory/immune genes. These M1- and M2-related changes progressed with the development of smoking-induced lung disease, with AM of smokers with COPD exhibiting further down-regulation of M1-related genes accompanied with further up-regulation of some M2-related genes. Conclusion: The data demonstrates that the modifications of the AM transcriptome associated with smoking result in a unique phenotype characterized by reprogramming of AM towards M1-deactivated partially M2-polarized macrophages and suggests that, while AM likely contribute to smoking-induced tissue remodeling, the role of AM in the early pathogenesis of smoking-induced COPD in humans is not inflammatory. This concept is a departure from the conventional concept that AM-mediated inflammation participates in the early derangements of the lung induced by smoking, and suggests a novel paradigm for conceptualizing COPD and developing new approaches to prevent the development of smoking-induced lung disease. Comparison of gene expression in alveolar macrophages of normal non-smokers and normal smokers and smokers with COPD

Project description:Background: When exposed to specific stimuli, macrophages exhibit distinct activation programs, M1 and M2 polarization, that define macrophage function as inflammatory/immune effectors or anti-inflammatory/tissue remodeling cells, respectively. Due to their position on the lung epithelial surface, alveolar macrophages (AM) directly interact with environmental stimuli such as cigarette smoke, the major risk factor for the development of chronic obstructive pulmonary disease (COPD). Based on the current paradigm that, in response to smoking, AM contribute to both inflammatory and tissue remodeling processes in the lung relevant to the pathogenesis of COPD, we hypothesized that chronic exposure to cigarette smoking activates both the M1 and M2 polarization programs in AM. Methods and Findings: To assess this hypothesis, global transcriptional profiling with TaqMan confirmation and flow cytometry analysis was carried out on AM obtained by bronchoalveolar lavage of 24 healthy nonsmokers, 34 healthy smokers and 12 smokers with COPD to assess the expression of 41 M1 genes and 32 M2 genes in each group. Contrary to our expectations, while there was up-regulation of some genes typical for M2-related phenotypes, AM of healthy smokers exhibited substantial suppression of M1-related inflammatory/immune genes. These M1- and M2-related changes progressed with the development of smoking-induced lung disease, with AM of smokers with COPD exhibiting further down-regulation of M1-related genes accompanied with further up-regulation of some M2-related genes. Conclusion: The data demonstrates that the modifications of the AM transcriptome associated with smoking result in a unique phenotype characterized by reprogramming of AM towards M1-deactivated partially M2-polarized macrophages and suggests that, while AM likely contribute to smoking-induced tissue remodeling, the role of AM in the early pathogenesis of smoking-induced COPD in humans is not inflammatory. This concept is a departure from the conventional concept that AM-mediated inflammation participates in the early derangements of the lung induced by smoking, and suggests a novel paradigm for conceptualizing COPD and developing new approaches to prevent the development of smoking-induced lung disease.

Project description:Rationale: Chronic Obstructive Pulmonary Disease (COPD) is considered a chronic inflammatory disease characterized by progressive airflow limitation and also has significant extrapulmonary (systemic) effects that lead to comorbid conditions. Very little is known about the pathomechanism of the disease. Objectives: Among inflammatory cell types, alveolar macrophages appear to have a key role in initiating and/or sustaining disease progression. These cells are derived from peripheral monocytes. Identification of disease and cell type specific gene expression profiles can be revealing and also practically useful in order to diagnose and characterize disease progression and the effect of drug treatment. Methods: We used Affymetrix microarrays to obtain gene expression data of alveolar macrophages and circulating monocytes of COPD and healthy control patients. The microarray results were confirmed by quantitative real-time polymerase chain reaction in multiple patient collections. Measurements and Main Results: We have identified gene sets specifically associated with COPD in alveolar macrophages and also in monocytes. Immune function, responses to stimuli, and cell death related genes appear to be impacted in both cell types. Remarkably, there is an overlapping gene set between the two cell types. Conclusions: Taken together, our data show that COPD-specific gene signatures can be identified and validated, and that the disease also affects peripheral monocytes. Moreover, monocytes and alveolar macrophages carry overlapping gene expression signatures. Our findings further support the notion that altered responsiveness to stimuli is the key characteristic of alveolar macrophages and also of their precursors, peripheral monocytes. Brochoalveolar lavage fluid samples were collected from of COPD and healthy control patients. Alveolar macrophages were isolated using Percoll gradient centrifugation, isolated using CD14+ magnetic beads, and total RNA was extracted using Qiagen RNeasy Kit. The monocyte samples represent a pool of RNA from 5 patients. Total RNA was labeled with biotin and individual samples were hybridized to Affymetrix HG U133A GeneChips. Affymetrix data files were analyzed using GeneSpring 7.3 software. Using a non-parametric statistical test, we compared the gene expression patterns of the COPD and the healthy control patients and identified a set a genes that showed differential expression between the two groups.

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Single Cell RNA-Sequencing Identifies ferroptotic differences of alveolar macrophages in COPD

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