Identification of a nerve-associated, lung-resident interstitial macrophage subset with distinct localization and immunoregulatory properties [bulk-seq]
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ABSTRACT: Tissue-resident macrophages are a diverse population of cells that perform specialized functions including sustaining tissue homeostasis and tissue surveillance. Here we report an interstitial subset of CD169+ lung-resident macrophages that are transcriptionally and developmentally distinct from alveolar macrophages (AMs). They are primarily localized around the airways and are found in close proximity to the sympathetic nerves located in the bronchovascular bundle. These nerve- and airway-associated macrophages (NAMs) are tissue-resident, yolk sac-derived, self-renewing, and do not require CCR2+ monocytes for development or maintenance. Unlike AMs, the development of NAMs requires CSF1, but not GM-CSF. Bulk population and single cell transcriptome analysis indicated that NAMs are distinct from other lung resident macrophage subsets and highly express immunoregulatory genes under steady state and inflammatory conditions. NAMs proliferated robustly following influenza infection and activation with the TLR ligand poly I:C, and in their absence, the inflammatory response was augmented resulting in excessive production of inflammatory cytokines and innate immune cell infiltration. Overall, our study provides insights into a distinct subset of airway-associated pulmonary macrophages that function to maintain immune and tissue homeostasis.
Project description:Tissue-resident macrophages are a diverse population of cells that perform specialized functions including sustaining tissue homeostasis and tissue surveillance. Here we report an interstitial subset of CD169+ lung-resident macrophages that are transcriptionally and developmentally distinct from alveolar macrophages (AMs). They are primarily localized around the airways and are found in close proximity to the sympathetic nerves located in the bronchovascular bundle. These nerve- and airway-associated macrophages (NAMs) are tissue-resident, yolk sac-derived, self-renewing, and do not require CCR2+ monocytes for development or maintenance. Unlike AMs, the development of NAMs requires CSF1, but not GM-CSF. Bulk population and single cell transcriptome analysis indicated that NAMs are distinct from other lung resident macrophage subsets and highly express immunoregulatory genes under steady state and inflammatory conditions. NAMs proliferated robustly following influenza infection and activation with the TLR ligand poly I:C, and in their absence, the inflammatory response was augmented resulting in excessive production of inflammatory cytokines and innate immune cell infiltration. Overall, our study provides insights into a distinct subset of airway-associated pulmonary macrophages that function to maintain immune and tissue homeostasis.
Project description:Recent studies suggest that training of innate immune cells such as tissue-resident macrophages by repeated noxious stimuli can heighten host defense responses. However, it remains unclear whether trained immunity of tissue-resident macrophages also comprises enhanced injury resolution capacity to counterbalance the heightened inflammatory responses. Here, we studied lung-resident alveolar macrophages (AMs) pre-challenged with either the bacterial endotoxin or with Pseudomonas aeruginosa and observed that these trained AMs showed greater resilience to pathogen-induced cell death. Transcriptomic analysis, and functional assays showed greater capacity of trained AMs to efferocytosis of cellular- debris, and facilitate injury resolution. Single-cell high-dimensional mass-cytometry analysis and lineage tracing demonstrated that training induces an expansion of a MERTKhiMarcohiCD163+F4/80low lung-resident AMs subset with pro-resolving phenotypes. Training epigenetically reprogrammed AMs to express a higher level of the transcription factor KLF4 which in turn upregulates the efferocytosis receptor MERTK. Adoptive transfer of these trained AMs restricted inflammatory lung injury in recipient mice exposed to lethal Pseudomonas aeruginosa. Thus, our study has identified a unique subset of tissue-resident trained macrophages which prevent hyper-inflammation and restore tissue homeostasis following pathogen challenge.
Project description:Recent studies suggest that training of innate immune cells such as tissue-resident macrophages by repeated noxious stimuli can heighten host defense responses. However, it remains unclear whether trained immunity of tissue-resident macrophages also comprises enhanced injury resolution capacity to counterbalance the heightened inflammatory responses. Here, we studied lung-resident alveolar macrophages (AMs) pre-challenged with either the bacterial endotoxin or with Pseudomonas aeruginosa and observed that these trained AMs showed greater resilience to pathogen-induced cell death. Transcriptomic analysis, and functional assays showed greater capacity of trained AMs to efferocytosis of cellular- debris, and facilitate injury resolution. Single-cell high-dimensional mass-cytometry analysis and lineage tracing demonstrated that training induces an expansion of a MERTKhiMarcohiCD163+F4/80low lung-resident AMs subset with pro-resolving phenotypes. Training epigenetically reprogrammed AMs to express a higher level of the transcription factor KLF4 which in turn upregulates the efferocytosis receptor MERTK. Adoptive transfer of these trained AMs restricted inflammatory lung injury in recipient mice exposed to lethal Pseudomonas aeruginosa. Thus, our study has identified a unique subset of tissue-resident trained macrophages which prevent hyper-inflammation and restore tissue homeostasis following pathogen challenge.
Project description:Lung diseases, such as cystic fibrosis and COPD, are characterized by mucus obstruction and chronic airway inflammation, but their mechanistic link remains poorly understood. Here, we focused on the role of the mucostatic airway microenvironment on epigenetic reprogramming of airway macrophages (AM) and resulting transcriptomic and phenotypical changes. Using a muco-obstructive mouse model (Scnn1b-transgenic), we identified epigenetically controlled, differentially regulated pathways and transcription factors involved in inflammatory responses and macrophage polarization. Ex vivo stimulation of wild-type AMs with mucus induced gene expression changes, comparable with those observed in AMs from Scnn1b-transgenic mice. Functionally, AMs from Scnn1b-transgenic mice displayed impaired efferocytosis, phagocytosis and excessive inflammatory responses upon lipopolysaccharide challenge, mediated through enhanced Irf1 activity and expression. Our data show that mucostasis induces epigenetic reprogramming of AMs, leading to changes favoring tissue damage and disease progression. Targeting of these altered AMs may support therapeutic approaches in patients with muco-obstructive lung diseases.
Project description:Lung diseases, such as cystic fibrosis and COPD, are characterized by mucus obstruction and chronic airway inflammation, but their mechanistic link remains poorly understood. Here, we focused on the role of the mucostatic airway microenvironment on epigenetic reprogramming of airway macrophages (AM) and resulting transcriptomic and phenotypical changes. Using a muco-obstructive mouse model (Scnn1b-transgenic), we identified epigenetically controlled, differentially regulated pathways and transcription factors involved in inflammatory responses and macrophage polarization. Ex vivo stimulation of wild-type AMs with mucus induced gene expression changes, comparable with those observed in AMs from Scnn1b-transgenic mice. Functionally, AMs from Scnn1b-transgenic mice displayed impaired efferocytosis, phagocytosis and excessive inflammatory responses upon lipopolysaccharide challenge, mediated through enhanced Irf1 activity and expression. Our data show that mucostasis induces epigenetic reprogramming of AMs, leading to changes favoring tissue damage and disease progression. Targeting of these altered AMs may support therapeutic approaches in patients with muco-obstructive lung diseases.
Project description:Lung diseases, such as cystic fibrosis and COPD, are characterized by mucus obstruction and chronic airway inflammation, but their mechanistic link remains poorly understood. Here, we focused on the role of the mucostatic airway microenvironment on epigenetic reprogramming of airway macrophages (AM) and resulting transcriptomic and phenotypical changes. Using a muco-obstructive mouse model (Scnn1b-transgenic), we identified epigenetically controlled, differentially regulated pathways and transcription factors involved in inflammatory responses and macrophage polarization. Ex vivo stimulation of wild-type AMs with mucus induced gene expression changes, comparable with those observed in AMs from Scnn1b-transgenic mice. Functionally, AMs from Scnn1b-transgenic mice displayed impaired efferocytosis, phagocytosis and excessive inflammatory responses upon lipopolysaccharide challenge, mediated through enhanced Irf1 activity and expression. Our data show that mucostasis induces epigenetic reprogramming of AMs, leading to changes favoring tissue damage and disease progression. Targeting of these altered AMs may support therapeutic approaches in patients with muco-obstructive lung diseases.
Project description:Lung diseases, such as cystic fibrosis and COPD, are characterized by mucus obstruction and chronic airway inflammation, but their mechanistic link remains poorly understood. Here, we focused on the role of the mucostatic airway microenvironment on epigenetic reprogramming of airway macrophages (AM) and resulting transcriptomic and phenotypical changes. Using a muco-obstructive mouse model (Scnn1b-transgenic), we identified epigenetically controlled, differentially regulated pathways and transcription factors involved in inflammatory responses and macrophage polarization. Ex vivo stimulation of wild-type AMs with mucus induced gene expression changes, comparable with those observed in AMs from Scnn1b-transgenic mice. Functionally, AMs from Scnn1b-transgenic mice displayed impaired efferocytosis, phagocytosis and excessive inflammatory responses upon lipopolysaccharide challenge, mediated through enhanced Irf1 activity and expression. Our data show that mucostasis induces epigenetic reprogramming of AMs, leading to changes favoring tissue damage and disease progression. Targeting of these altered AMs may support therapeutic approaches in patients with muco-obstructive lung diseases.
Project description:Lung diseases, such as cystic fibrosis and COPD, are characterized by mucus obstruction and chronic airway inflammation, but their mechanistic link remains poorly understood. Here, we focused on the role of the mucostatic airway microenvironment on epigenetic reprogramming of airway macrophages (AM) and resulting transcriptomic and phenotypical changes. Using a muco-obstructive mouse model (Scnn1b-transgenic), we identified epigenetically controlled, differentially regulated pathways and transcription factors involved in inflammatory responses and macrophage polarization. Ex vivo stimulation of wild-type AMs with mucus induced gene expression changes, comparable with those observed in AMs from Scnn1b-transgenic mice. Functionally, AMs from Scnn1b-transgenic mice displayed impaired efferocytosis, phagocytosis and excessive inflammatory responses upon lipopolysaccharide challenge, mediated through enhanced Irf1 activity and expression. Our data show that mucostasis induces epigenetic reprogramming of AMs, leading to changes favoring tissue damage and disease progression. Targeting of these altered AMs may support therapeutic approaches in patients with muco-obstructive lung diseases.
Project description:Tissue resident macrophages show their specific function to maintain homeostasis in our body. Dysfunction of alveolar macrophages (AMs), which regulate the proper amount of surfactant protein, leads to the development of pulmonary alveolar proteinosis (PAP). Here we found that inflammation ruins the function of AMs and is one of the causes of secondary PAP. Inflammation leads to the loss of specific gene expression pattern of AMs and furthermore, it leads to gain the specific gene expression pattern of other tissue resident macrophages and DC lineage. We also found the critical roles for Bach2 expressed in AMs and T cells, whose expression is induced by IFNg released from T cells. Bach2 bounds to super-enhancer regions of the inflammatory genes of the myeloid lineage and represses excess inflammation in lungs. Our results suggest that Bach2 function among several cell lineages to modify the inflammation, maintaining homeostasis in lungs.
Project description:Respiratory viral infections reprogram pulmonary macrophages with altered anti-infectious functions. However, the potential function of virus-trained macrophages in antitumor immunity in the lung, a preferential target of both primary and metastatic malignancies, is not well understood. Using mouse models of influenza and lung metastatic tumors, we show here that influenza trains respiratory mucosal-resident alveolar macrophages (AMs) to exert long-lasting and tissue-specific antitumor immunity. Trained AMs infiltrate tumor lesions and have enhanced phagocytic and tumor cell cytotoxic functions, which are associated with epigenetic, transcriptional and metabolic resistance to tumor-induced immune suppression. Generation of antitumor trained immunity in AMs is dependent on interferon-γ and natural killer cells. Notably, human AMs with trained immunity traits in non-small cell lung cancer tissue are associated with a favorable immune microenvironment. These data reveal a function for trained resident macrophages in pulmonary mucosal antitumor immune surveillance. Induction of trained immunity in tissue-resident macrophages might thereby be a potential antitumor strategy.