High amplitude stretching of ATII cells and fibroblasts results in profibrotic effects.

Background: Inappropriate mechanical forces act on alveolar epithelial cells during mechanical ventilation e.g. in ARDS and possibly in patients with pulmonary fibrosis. These forces can cause lung injury and may contribute to the development or aggravation of pulmonary fibrosis. Aim of the study: We investigated the hypothesis that high amplitude mechanical stretching of alveolar type II (ATII) cells and lung fibroblasts promotes profibrotic processes. Material and Methods: ATII cells and fibroblasts were stretched on elastic membranes using a pattern of higher amplitudes ("unphysiological"). The production of profibrotic cytokines and extra cellular matrix (ECM) proteins were investigated in supernatants. In addition, we determined the expression of relevant microRNAs (miRNA) and the process of epithelial-mesenchymal transition (EMT) in ATII cells. Results: Unphysiological stretch of ATII cells led to increased release of TGF-ß1 into supernatants. We also found elevated protein levels of collagen I and IV in supernatants of stretched cells. By contrast, stretching of fibroblasts changed neither the expression of fibrosis-modulating factors nor ECM-proteins. However, fibroblasts significantly withstood stretch-induced cell injury and seemed to have a survival benefit. Further, stretched ATII cells exhibited a higher expression of miRNAs (miR-15b, miR-25, let-7d) relevant to EMT. The process of EMT, which is characterized by an increase of vimentin and a decrease of cytokeratin expression, was significantly accelerated due to stretching of ATII cells. Conclusion: These data provide evidence that unphysiological mechanical stretching of lung cells induced several profibrotic effects and accelerated EMT, which may have critical implications in terms of development or aggravation of pulmonary fibrosis in the clinical context.

The Wnt secretion protein Evi/Gpr177 promotes glioma tumourigenesis.

Malignant astrocytomas are highly aggressive brain tumours with poor prognosis. While a number of structural genomic changes and dysregulation of signalling pathways in gliomas have been described, the identification of biomarkers and druggable targets remains an important task for novel diagnostic and therapeutic approaches. Here, we show that the Wnt-specific secretory protein Evi (also known as GPR177/Wntless/Sprinter) is overexpressed in astrocytic gliomas. Evi/Wls is a core Wnt signalling component and a specific regulator of pan-Wnt protein secretion, affecting both canonical and non-canonical signalling. We demonstrate that its depletion in glioma and glioma-derived stem-like cells led to decreased cell proliferation and apoptosis. Furthermore, Evi/Wls silencing in glioma cells reduced cell migration and the capacity to form tumours in vivo. We further show that Evi/Wls overexpression is sufficient to promote downstream Wnt signalling. Taken together, our study identifies Evi/Wls as an essential regulator of glioma tumourigenesis, identifying a pathway-specific protein trafficking factor as an oncogene and offering novel therapeutic options to interfere with the aberrant regulation of growth factors at the site of production.