The release of the metalloproteinase meprin β onto exosomes

The idiopathic inflammatory bowel disease (IBD) has been increasing in its incidence over the last decades and comes along with an enormous social and economic impact especially for younger patients. The full understanding of the role that the metalloproteinase meprin β (metalloprotease from renal tissue β) plays is unclear, but it was found transcriptionally downregulated in IBD patients. It is important for proper mucus detachment in the small intestine as a shed soluble proteinase. We aim to identify whether meprin β can be sorted to extracellular vesicles (EVs) and if it can be sorted in its soluble form from EVs again. Purification of extracellular vesicles from stimulated cell culture media, murine intestinal tissue and chyme combined with biochemical analysis and electron microscopy imaging techniques, we aim to identify conditions and factors that play a role for the release of meprin β onto exosomes and if this is compartment specific for the intestinal tract. We successfully showed in cell culture experiments, that loss of meprin β sheddases ADAM10 and ADAM17 induces the release of meprin on extracellular vesicles. Stable overexpression of meprin β in ADAM10/17 deficient and control wild type cells allows to test pro-inflammatory stimuli for their ability to induce meprin β release on extracellular vesicles. Further we were able to isolate extracellular vesicles from healthy murine intestine and thereby show an exosomal release of meprin β in the small intestine which is a first step of the transfer from cell culture experiments to mouse model research. Overall, our findings shed light on the complex mechanisms of exosomal protein secretion of meprin β. Here, we propose that the loss of ADAM10/17 and pro inflammatory stimulation induce exosomal release of meprin β and hence contribute to a changed proteolytic cleavage pattern of the intestinal mucosa underlining the potential of meprin β as a therapeutic target in chronic inflammatory bowel disease.