TNFα triggers release of extracellular vesicles containing TNFR1 and TRADD, which can modulate TNFα responses of the parental cells

Tumor necrosis factor-alpha (TNF alpha)-induced reactions are effective to maintain homeostasis; however, excessive responses play progressive roles in the pathogenesis of various chronic inflammatory diseases. We demonstrate that TNF alpha triggered the release of its receptor TNFR1 as a content of extracellular vesicles (EVs) from the human bronchial epithelial cell, BEAS-2b. The TNFR1 cytoplasmic domain binding partner, TNFR-associated death domain (TRADD), was released by TNFa treatment along with TNFR1. TNF alpha-triggered release of EVs was decreased in the presence of amitriptyline, an inhibitor of acid sphingomyelinase (A-SMase), or of GW4869, an inhibitor of neutral sphingomyelinase (N-SMase), indicating that EVs containing TNFR1 and TRADD are released through A-SMase and N-SMase dependent manners. From sucrose density gradient analysis, each sphingomyelinase is involved in the generation of distinct populations of EVs. Inhibition of A-SMase or N-SMase resulted in significantly increased responses to TNFa in parental cells. Given that TRADD serves as a platform for the assembly of subsequent signaling molecules, the TNFa triggered release of TNFR1 and TRADD might be an effective strategy for down regulation of the TNFa responses of parental cells. (C) 2015 Elsevier Inc. All rights reserved.