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Monocyte-derived alveolar macrophages are key drivers of smoke-induced lung inflammation and tissue remodeling.

ABSTRACT: Smoking is a leading risk factor of chronic obstructive pulmonary disease (COPD), that is characterized by chronic lung inflammation, tissue remodeling and emphysema. Although inflammation is critical to COPD pathogenesis, the cellular and molecular basis underlying smoking-induced lung inflammation and pathology remains unclear. Using murine smoke models and single-cell RNA-sequencing, we show that smoking establishes a self-amplifying inflammatory loop characterized by an influx of molecularly heterogeneous neutrophil subsets and excessive recruitment of monocyte-derived alveolar macrophages (MoAM). In contrast to tissue-resident AM, MoAM are absent in homeostasis and characterized by a pro-inflammatory gene signature. Moreover, MoAM represent 46% of AM in emphysematous mice and express markers causally linked to emphysema. We also demonstrate the presence of pro-inflammatory and tissue remodeling associated MoAM orthologs in humans that are significantly increased in emphysematous COPD patients. Inhibition of the IRAK4 kinase depletes a rare inflammatory neutrophil subset, diminishes MoAM recruitment, and alleviates inflammation in the lung of cigarette smoke-exposed mice. This study extends our understanding of the molecular signaling circuits and cellular dynamics in smoking-induced lung inflammation and pathology, highlights the functional consequence of monocyte and neutrophil recruitment, identifies MoAM as key drivers of the inflammatory process, and supports their contribution to pathological tissue remodeling.

SUBMITTER: Wohnhaas CT

PROVIDER: S-EPMC10859862 | biostudies-literature | 2024

REPOSITORIES: biostudies-literature

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Monocyte-derived alveolar macrophages are key drivers of smoke-induced lung inflammation and tissue remodeling.

Wohnhaas Christian T CT Baßler Kevin K Watson Carolin K CK Shen Yang Y Leparc Germán G GG Tilp Cornelia C Heinemann Fabian F Kind David D Stierstorfer Birgit B Delić Denis D Brunner Thomas T Gantner Florian F Schultze Joachim L JL Viollet Coralie C Baum Patrick P

Frontiers in immunology 20240129

Smoking is a leading risk factor of chronic obstructive pulmonary disease (COPD), that is characterized by chronic lung inflammation, tissue remodeling and emphysema. Although inflammation is critical to COPD pathogenesis, the cellular and molecular basis underlying smoking-induced lung inflammation and pathology remains unclear. Using murine smoke models and single-cell RNA-sequencing, we show that smoking establishes a self-amplifying inflammatory loop characterized by an influx of molecularly ...[more]

PMID: 38348034

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Project description:BackgroundChronic obstructive pulmonary disease (COPD) is a frequently encountered disease condition in clinical practice mainly caused by cigarette smoke (CS). The aim of this study was to investigate the protective roles of human adipose-derived stem cells-derived exosomes (ADSCs-Exo) in CS-induced lung inflammation and injury and explore the underlying mechanism by discovering the effects of ADSCs-Exo on alveolar macrophages (AMs) pyroptosis.MethodsADSCs were isolated from human adipose tissues harvested from three healthy donors, and then ADSCs-Exo were isolated. In vivo, 24 age-matched male C57BL/6 mice were exposed to CS for 4 weeks, followed by intratracheal administration of ADSCs-Exo or phosphate buffered saline. In vitro, MH-S cells, derived from mouse AMs, were stimulated by 2% CS extract (CSE) for 24 h, followed by the treatment of ADSCs-Exo or phosphate buffered saline. Pulmonary inflammation was analyzed by detecting pro-inflammatory cells and mediators in the bronchoalveolar lavage fluid. Lung histology was assessed by hematoxylin and eosin staining. Mucus production was determined by Alcian blue-periodic acid-Schiff staining. The profile of AMs pyroptosis was evaluated by detecting the levels of pyroptosis-indicated proteins. The inflammatory response in AMs and the phagocytic activity of AMs were also investigated.ResultsIn mice exposed to CS, the levels of pro-inflammatory cells and mediators were significantly increased, mucus production was markedly increased and lung architecture was obviously disrupted. AMs pyroptosis was elevated and AMs phagocytosis was inhibited. However, the administration of ADSCs-Exo greatly reversed these alterations caused by CS exposure. Consistently, in MH-S cells with CSE-induced properties modelling those found in COPD, the cellular inflammatory response was elevated, the pyroptotic activity was upregulated while the phagocytosis was decreased. Nonetheless, these abnormalities were remarkably alleviated by the treatment of ADSCs-Exo.ConclusionsADSCs-Exo effectively attenuate CS-induced airway mucus overproduction, lung inflammation and injury by inhibiting AMs pyroptosis. Therefore, hADSCs-Exo may be a promising cell-free therapeutic candidate for CS-induced lung inflammation and injury.

Project description:IntroductionAcute lung injury (ALI) and its subsequent progression to acute respiratory distress syndrome (ARDS) are severe respiratory conditions. They are marked by rapid lung function deterioration and extensive pulmonary inflammation, often resulting in critical patient outcomes. Alveolar macrophages (AMs) and monocyte-derived macrophages (MDMs) are two distinct subsets of lung macrophages present in the alveoli during ALI. Both are critical mediators of pulmonary inflammation. Our study examined the interplay between AMs and MDMs in the inflammatory environment of ALI/ARDS.MethodsMice were treated with lipopolysaccharide (LPS) to establish ALI models. The lung tissues of mice were subjected to hematoxylin-eosin staining to observe the degree of tissue damage. In vivo, CCR2-deficient mice or depleting peripheral blood mononuclear cells by clodronate liposomes were used to reduce MDMs recruitment. The bronchoalveolar lavage fluid (BALF) supernatants were used for cytokine and total protein analyses. AMs and MDMs in the BALF were analyzed by flow cytometry. The levels of AMs death were determined through propidium iodide staining and measured by flow cytometry. In vitro, primary AMs were exposed to MDM-conditioned medium or TNF-α, and their death levels were assessed under a fluorescence microscope with propidium iodide staining.ResultsAMs significantly decrease in number and undergo extensive cell death during ALI. The reduced MDMs recruitment can increase the number of AMs, reduce AMs death, and alleviate lung injury. In vitro, MDM-conditioned medium can induce AMs death and TNF-α is one of the major secretions. It indicates that TNF-α stimulation in vitro promotes AMs death. In vivo, MDMs are identified as the primary cells secreting TNF-α. Additionally, the treatment with TNF-α antagonists can reduce AMs death and the severity of lung injury.ConclusionOur study demonstrates that MDMs contribute to AMs death during ALI through TNF-α. Targeting TNF-α may offer a therapeutic strategy to mitigate AMs death and lung injury in ALI/ARDS.

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Monocyte-derived alveolar macrophages are key drivers of smoke-induced lung inflammation and tissue remodeling.

Publications

Monocyte-derived alveolar macrophages are key drivers of smoke-induced lung inflammation and tissue remodeling.

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