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Recruited monocytes/macrophages drive pulmonary neutrophilic inflammation and irreversible lung tissue remodeling in cystic fibrosis.

ABSTRACT: Controlled recruitment of C-C Motif Chemokine Receptor 2 (CCR2)-positive monocytes into lung tissues is a crucial component of the host immune response to infections. Pathogenesis of cystic fibrosis (CF) lung remodeling, which ultimately leads to respiratory failure, is caused by chronic infections and neutrophilic inflammation, but the immune mechanisms are not fully understood. Here, we show that lung explants from CF patients with severe disease contain abundant CCR2-positive classical monocytes in the submucosal tissues of small airways and areas of tissue remodeling. Recapitulating human CF lung remodeling by repeatedly exposing CF mice to lipopolysaccharide (LPS), and by using genetic ablation or pharmacological inhibition of CCR2, we demonstrate that CCR2-dependent accumulation of classical monocytes and monocyte-derived macrophages drive lung neutrophilia, pathogenic Transforming Growth Factor Beta signaling and irreversible lung tissue scarring. Importantly, six weeks after cessation of LPS exposure, the lungs of CF mice still have elevated numbers of pro-inflammatory monocytes with higher expression of neutrophil chemoattractants, thus perpetuating recruitment of neutrophils and lung tissue damage. Lastly, we demonstrate that the increased accumulation of immune cells to inflamed lungs is driven by dysfunctional CF transmembrane conductance regulator (CFTR) expression in CCR2-positive cells. These studies identify uncontrolled recruitment of CCR2-positive cells as a key driver of lung remodeling, and as a novel therapeutic target for patients with CF for which lung hyper-inflammation and tissue damage remain an issue despite recent advances in CFTR-specific therapeutics. Keywords: monocytes; macrophages; neutrophils; chronic lung inflammation; lipopolysaccharide; recruitment; CC-motif chemokine receptor 2; transforming growth factor beta; lung remodeling; cystic fibrosis

ORGANISM(S): Mus musculus

PROVIDER: GSE217102 | GEO | 2022/12/01

REPOSITORIES: GEO

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Project description:Dysfunction of the cystic fibrosis transmembrane regulator (CFTR) in cystic fibrosis (CF) results in exaggerated and chronic inflammation as well as increased susceptibility to chronic pulmonary infections, in particular with Pseudomonas aeruginosa. Based on the concept that host immune responses do not seem to be adequate to eradicate P.aeruginosa from the lungs of CF patients and that dendritic cells (DC) play an important role in initiating and shaping adaptive immune responses, this study analyzed the role of CFTR in bone marrow-derived murine DC from CFTR knockout (CF) mice with and without exposure to P.aeruginosa. DC expressed CFTR mRNA and protein, although at much lower levels compared to whole lung. Microarray analysis of gene expression levels in DC generated from CF and wild type (WT) mice revealed significantly different expression of 16 genes in CF DC compared to WT DC. Among the genes with lower expression in CF DC was Caveolin-1, a membrane lipid raft protein. Messenger RNA and protein levels of Caveolin-1 were decreased in the CF DC compared to WT DC. Consistently, the active form of sterol-responsive element binding protein (SREBP), a negative regulator of Caveolin-1 expression, was increased in CF DC. Following exposure to P.aeruginosa, gene expression levels in CF and WT DC changed for 912 genes involved in inflammation, chemotaxis, signaling, cell cycling and apoptosis more than 1.5-fold. Among the genes that showed a different response between WT and CF DC infected with P.aeruginosa, were 3Î²-hydroxysterol-Î7 reductase (Dhcr7) and stearoyl-CoA desaturase 2 (Scd2), two enzymes involved in the lipid metabolism that are also regulated by SREBP. These results suggest that CFTR dysfunction in non-epithelial cells results in changes in the expression of genes encoding factors involved in membrane structure and lipid-metabolism. These membrane alterations in immune cells may contribute to the abnormal inflammatory and immune response characteristic of CF. Experiment Overall Design: comparison of gene expression in dendritic cells of cystic fibrosis mice without or with Pseudosmonas aeruginosa infection vs wild type dendritic cell controls

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Recruited monocytes/macrophages drive pulmonary neutrophilic inflammation and irreversible lung tissue remodeling in cystic fibrosis.

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