The disruptive effects of COPD exacerbation-associated factors on epithelial repair responses.

Introduction: Exacerbations of chronic obstructive pulmonary disease (COPD) increase mortality risk and can lead to accelerated loss of lung function. The increased inflammatory response during exacerbations contributes to worsening of airflow limitation, but whether it also impacts epithelial repair is unclear. Therefore, we studied the effect of the soluble factor micro-environment during COPD exacerbations on epithelial repair using an exacerbation cocktail (EC), composed of four factors that are increased in COPD lungs during exacerbations (IL-1ß, IL-6, IL-8, TNF-α). Methods: Mouse organoids (primary CD31-CD45-Epcam+ cells co-cultured with CCL206 fibroblasts) were used to study epithelial progenitor behavior. Mature epithelial cell responses were evaluated using mouse precision cut lung slices (PCLS). The expression of epithelial supportive factors was assessed in CCL206 fibroblasts and primary human lung fibroblasts. Results: EC exposure increased the number and size of organoids formed, and upregulated Lamp3, Muc5ac and Muc5b expression in day 14 organoids. In PCLS, EC imparted no effect on epithelial marker expression. Pre-treatment of CCL206 fibroblasts with EC was sufficient to increase organoid formation. Additionally, the expression of Il33, Tgfa and Areg was increased in CCL206 fibroblasts from EC treated organoids, but these factors individually did not affect organoid formation or size. However, TGF-α downregulated Foxj1 expression and upregulated Aqp5 expression in day 14 organoids. Conclusions: EC exposure stimulates organoid formation and growth, but it alters epithelial differentiation. EC changes the epithelial progenitor support function of fibroblasts which contributes to observed effects on epithelial progenitors.

Therapeutic Targeting of IL-11 for Chronic Lung Disease.

Interleukin (IL)-11 was originally recognized as an immunomodulatory and hematopoiesis-inducing cytokine. However, although IL-11 is typically not found in healthy individuals, it is now becoming evident that IL-11 may play a role in diverse pulmonary conditions, including IPF, asthma, and lung cancer. Additionally, experimental strategies targeting IL-11, such as humanized antibodies, have recently been developed, revealing the therapeutic potential of IL-11. Thus, further insight into the underlying mechanisms of IL-11 in lung disease may lead to the ability to interfere with pathological conditions that have a clear need for disease-modifying treatments, such as IPF. In this review, we outline the effects, expression, signaling, and crosstalk of IL-11 and focus on its role in lung disease and its potential as a therapeutic target.

TGF-ß activation impairs fibroblast ability to support adult lung epithelial progenitor cell organoid formation.

Transforming growth factor-ß (TGF-ß)-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-ß 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-ß pretreatment of both phFB and MRC5 impaired organoid-supporting ability. We performed RNA sequencing of TGF-ß-treated phFB, which revealed altered expression of key Wnt signaling pathway components and Wnt/ß-catenin target genes, and modulated expression of secreted factors involved in mesenchymal-epithelial signaling. TGF-ß profoundly skewed the transcriptional program induced by the Wnt/ß-catenin activator CHIR99021. Supplementing organoid culture media recombinant hepatocyte growth factor or fibroblast growth factor 7 promoted organoid formation when using TGF-ß pretreated fibroblasts. In conclusion, TGF-ß-induced myofibroblast differentiation results in Wnt/ß-catenin pathway skewing and impairs fibroblast ability to support epithelial repair likely through multiple mechanisms, including modulation of secreted growth factors.