The search for translational pain outcomes to refine analgesic development: Where did we come from and where are we going?

Pain measures traditionally used in rodents record mere reflexes evoked by sensory stimuli; the results thus may not fully reflect the human pain phenotype. Alterations in physical and emotional functioning, pain-depressed behaviors and facial pain expressions were recently proposed as additional pain outcomes to provide a more accurate measure of clinical pain in rodents, and hence to potentially enhance analgesic drug development. We aimed to review how preclinical pain assessment has evolved since the development of the tail flick test in 1941, with a particular focus on a critical analysis of some nonstandard pain outcomes, and a consideration of how sex differences may affect the performance of these pain surrogates. We tracked original research articles in Medline for the following periods: 1973-1977, 1983-1987, 1993-1997, 2003-2007, and 2014-2018. We identified 606 research articles about alternative surrogate pain measures, 473 of which were published between 2014 and 2018. This indicates that preclinical pain assessment is moving toward the use of these measures, which may soon become standard procedures in preclinical pain laboratories.FPU grant from the Spanish Ministry of Education, Culture and SportsSpanish Ministry of Economy and Competitiveness (MINECO, grant SAF2016-80540-R)Ramón Areces FoundationJunta de Andalucía (grant CTS 109)Esteve PharmaceuticalsEuropean Regional Development Fund (ERDF

RNA delivery by extracellular vesicles in mammalian cells and its applications.

The term 'extracellular vesicles' refers to a heterogeneous population of vesicular bodies of cellular origin that derive either from the endosomal compartment (exosomes) or as a result of shedding from the plasma membrane (microvesicles, oncosomes and apoptotic bodies). Extracellular vesicles carry a variety of cargo, including RNAs, proteins, lipids and DNA, which can be taken up by other cells, both in the direct vicinity of the source cell and at distant sites in the body via biofluids, and elicit a variety of phenotypic responses. Owing to their unique biology and roles in cell-cell communication, extracellular vesicles have attracted strong interest, which is further enhanced by their potential clinical utility. Because extracellular vesicles derive their cargo from the contents of the cells that produce them, they are attractive sources of biomarkers for a variety of diseases. Furthermore, studies demonstrating phenotypic effects of specific extracellular vesicle-associated cargo on target cells have stoked interest in extracellular vesicles as therapeutic vehicles. There is particularly strong evidence that the RNA cargo of extracellular vesicles can alter recipient cell gene expression and function. During the past decade, extracellular vesicles and their RNA cargo have become better defined, but many aspects of extracellular vesicle biology remain to be elucidated. These include selective cargo loading resulting in substantial differences between the composition of extracellular vesicles and source cells; heterogeneity in extracellular vesicle size and composition; and undefined mechanisms for the uptake of extracellular vesicles into recipient cells and the fates of their cargo. Further progress in unravelling the basic mechanisms of extracellular vesicle biogenesis, transport, and cargo delivery and function is needed for successful clinical implementation. This Review focuses on the current state of knowledge pertaining to packaging, transport and function of RNAs in extracellular vesicles and outlines the progress made thus far towards their clinical applications

The emerging role of exosomes in stress physiology

Acute activation of the stress response modulates an adaptive series of physiological changes to optimize an organism\u27s survival. One component of the stress response involves an induction of the innate immune system through the release of Hsp72, an endogenous danger associated molecular pattern rapidly released into the blood following stressor exposure. The mechanism of Hsp72 release is unknown, but recent findings suggest Hsp72 is release via the non-classical exosome releasing pathway. This dissertation explores the emerging role of exosomes during stress-induced immunomodulation. Exosomes, biologically active nanoparticles released by most cells in the body, encompass a variety of proteins and microRNA (miRNA) that can be modified in response injury, infection, or disease. The goals in this dissertation as follows: (1) characterize Hsp72 in the plasma, peripheral tissues, brain, and cerebrospinal fluid following acute stressor exposure; (2) investigate potential targets for stress-sensitive markers associated with exosomes; (3) explore the potential pathways activated during the stress response responsible for modulating exosomes; and (4) examine how stress-modified exosomes impact bacterial inflammation. We provide evidence in this dissertation that exposure to an acute stressor modifies Hsp72 expression and the miRNA character of circulating plasma exosomes in the absence of a pathogenic challenge or disease. Further, we identify sympathetic nervous system (SNS) activation as an important signal for part of the stress-evoked changes in circulating exosomes. Importantly, these stress-modified plasma exosomes contribute to enhanced host response during a bacterial challenge. Future research is necessary to determine both the cellular sources and targets of stress-modified exosomes