Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines
ABSTRACT The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell‐released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV‐associated functional activities. Finally, a checklist is provided with summaries of key points.
MicroRNA-513 Regulates B7-H1 Translation and Is Involved in IFN-γ-Induced B7-H1 Expression in Cholangiocytes
Abstract Biliary epithelial cells (cholangiocytes) respond to proinflammatory cytokines such as IFN-γ and actively participate in the regulation of biliary inflammatory response in the liver. B7-H1 (also known as CD274 or PD-L1) is a member of the B7 costimulatory molecules and plays a critical immunoregulatory role in cell-mediated immune responses. In this study, we show that resting human cholangiocytes in culture express B7-H1 mRNA, but not B7-H1 protein. IFN-γ induces B7-H1 protein expression and alters the microRNA (miRNA) expression profile in cholangiocytes. Of those IFN-γ-down-regulated miRNAs, we identified microRNA-513 (miR-513) with complementarity to the 3′-untranslated region of B7-H1 mRNA. Targeting of the B7-H1 3′-untranslated region by miR-513 results in translational repression. Transfection of cholangiocytes with an antisense oligonucleotide to miR-513 induces B7-H1 protein expression. Additionally, transfection of miR-513 precursor decreases IFN-γ-induced B7-H1 protein expression and consequently influences B7-H1-associated apoptotic cell death in cocultured Jurkat cells. Thus, miR-513 regulates B7-H1 translation and is involved in IFN-γ-induced B7-H1 expression in human cholangiocytes, suggesting a role for miRNA-mediated gene silencing in the regulation of cholangiocyte response to IFN-γ.