Transforming growth factor-beta (TGF-beta)-induced fibroblast-to-myofibroblast differentiation contributes to remodeling in chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis,... Show moreTransforming growth factor-beta (TGF-beta)-induced fibroblast-to-myofibroblast differentiation contributes to remodeling in chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis, but whether this impacts the ability of fibroblasts to support lung epithelial repair remains little explored. We pretreated human lung fibroblasts [primary (phFB) or MRC5 cells] with recombinant human TGF-beta to induce myofibroblast differentiation, then cocultured them with adult mouse lung epithelial cell adhesion molecule-positive cells (EpCAM(+)) to investigate their capacity to support epithelial organoid formation in vitro. While control phFB and MRC5 lung fibroblasts supported organoid formation of mouse EpCAM(+) cells, TGF-beta pretreatment of both phFB and MRC5 impaired organoid-supporting ability. We performed RNA sequencing of TGF beta-treated phFB. which revealed altered expression of key Wnt signaling pathway components and Wnt/beta-catenin target genes, and modulated expression of secreted factors involved in mesenchymal-epithelial signaling. TGF-beta profoundly skewed the transcriptional program induced by the Wnt/beta-catenin activator CHIR99021. Supplementing organoid culture media recombinant hepatocyte growth factor or fibroblast growth factor 7 promoted organoid formation when using TGF-beta pretreated fibroblasts. In conclusion, TGF-beta-induced myofibroblast differentiation results in Wnt/beta-catenin pathway skewing and impairs fibroblast ability to support epithelial repair likely through multiple mechanisms, including modulation of secreted growth factors. Show less
RATIONALE Chronic obstructive pulmonary disease patients and in particular smokers are more susceptible to respiratory infections contributing to acute exacerbations of disease. The... Show moreRATIONALE Chronic obstructive pulmonary disease patients and in particular smokers are more susceptible to respiratory infections contributing to acute exacerbations of disease. The immunoproteasome is a specialized type of proteasome destined to improve major histocompatibility complex (MHC) class I-mediated antigen presentation for the resolution of intracellular infections. OBJECTIVES To characterize immunoproteasome function in COPD and its regulation by cigarette smoke. METHODS Immunoproteasome expression and activity were determined in bronchoalveolar lavage (BAL) and lungs of human donors, COPD, and IPF patients, as well as in cigarette smoke-exposed mice. Smoke-mediated alteration of immunoproteasome activity and MHC I surface expression were analysed in human blood-derived macrophages. Immunoproteasome-specific MHC I antigen presentation was evaluated in spleen and lung immune cells that had been smoke-exposed in vitro or in vivo. MEASUREMENTS AND MAIN RESULTS Immunoproteasome and MHC I mRNA expression was reduced in BAL cells of COPD patients and in isolated alveolar macrophages of COPD and IPF patients. Exposure of immune cells to cigarette smoke extract in vitro reduced immunoproteasome activity and impaired immunoproteasome-specific MHC I antigen presentation. In vivo, acute cigarette smoke exposure dynamically regulated immunoproteasome function and MHC I antigen presentation in mouse BAL cells. End-stage COPD lungs showed markedly impaired immunoproteasome activities. CONCLUSIONS We here show for the first time that the activity of the immunoproteasome is impaired by cigarette smoke resulting in reduced MHC I antigen presentation. Regulation of immunoproteasome function by cigarette smoke may thus alter adaptive immune responses and add to prolonged infections and exacerbations in COPD and IPF. Show less
