Interplay of the iRhom2/ADAM17 axis and Piezo1 in lung responses to inflammation and mechanical stress

• Applicant: Professor Dr. Andreas Ludwig
• Subject Area: Pharmacology ; Pneumology, Thoracic Surgery
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 418426903

Inflammation in the lung can be decisively modulated by limited proteolysis of cell surface molecules (shedding). The cytokine TNF, growth factors of the EGF family, IL-6 receptors, transmembrane chemokines and cell adhesion molecules are shed from the cell surface by the metalloprotease ADAM17 and regulate vascular permeability, oedema formation and leukocyte recruitment in the lung. Recently, we demonstrated a critical cell-dependent role of ADAM17 in endothelium and smooth muscle in a mouse model of acute lung inflammation. The pseudoproteases iRhom1 and 2 act as critical regulators of ADAM17 by mediating transport from the ER to the Golgi, maturation, and surface expression. In the last funding period, we investigated the role of iRhom2 in lung inflammation in vitro and in vivo. We have described the induction of iRhom2 in epithelial, endothelial cells and macrophages by inflammatory stimuli and found that this leads to increased maturation and surface expression of ADAM17, which in turn promotes the release of TNF, IL6R, JAM-A and TGFα. In a mouse model of acute lung inflammation, we confirmed that iRhom2 acts proinflammatory by mediating the release of inflammatory mediators that promote leukocyte recruitment. We also found that ADAM17 activity is increased in endothelial and epithelial cells when they are exposed to mechanical stress, such as shearing or stretching of the cells. We were able to show that the mechanosensor Piezo-1 contributes decisively to the activation of ADAM17 in cell culture and in our ex vivo model of isolated, perfused lung. We hypothesise that the iRhom2/ADAM17 axis is an important inflammatory switch in the lung that can be mechanically activated via Piezo1. We aim to continue our studies of the iRhom2/ADAM17 axis in acute lung inflammation to better understand its mechanistic role in inflammatory leukocyte recruitment in the lung. To this end, we will continue to use our iRhom2-deficient mice and iRhom2-overexpressing mice in the acute lung inflammation model. In a next step, we will use these mice to investigate the role of the iRhom2/ADAM17 axis in mechanically induced lung injury in our ex vivo model of isolated perfused lung. To understand the role of the mechanoreceptor Piezo1 as an activator of the ADAM17/iRhom2 axis in mechanically stressed lung, we will use conditional Piezo1 knockout mice. To gain deeper insight into the mechanistic link between Piezo1 and ADAM17 activation, we will investigate Piezo1-mediated activation of kinases and their role in phosphorylation of iRhom2 in vitro. The aim of our study is to uncover a new pathway from mechanical activation via Piezo1 to phosphorylation of iRhom2 and enhanced ADAM17 activity leading to proinflammatory responses in the lung.

• DFG Programme: Research Grants