Purpose of reviewExtracellular vesicles released by prokaryote or eukaryote cells are emerging as mechanisms of cell-to-cell communication, by either physically interacting with the surface of target cells or transferring proteins/ peptides, lipids, carbohydrates, and nuclei acids to acceptor cells. Accumulating evidence indicates that extracellular vesicles, among other functions, regulate innate and adaptive immune responses. We revisit here the effects that extracellular vesicles of various origins have on innate immunity. Recent findingsExtracellular vesicles comprise a heterogeneous group of vesicles with different biogenesis, composition and biological properties, which include exosomes, microvesicles, apoptotic cell-derived extracellular vesicles, and other extracellular vesicles still not well characterized. Extracellular vesicles released by pathogens, leukocytes, nonhematopoietic cells, tumor cells, and likely allografts, can either stimulate or suppress innate immunity via multiple mechanisms. These include transfer to target leukocytes of proinflammatory or anti-inflammatory mediators, membrane receptors, enzymes, mRNAs, and noncoding RNAs; and interaction of extracellular vesicles with the complement and coagulation systems. As a result, extracellular vesicles affect differentiation, polarization, activation, tissue recruitment, cytokine and chemokine production, cytolytic and phagocytic function, and antigen transfer ability, of different types of innate immune cells.

Highlights d T cells express the neurokinin 1 receptor (NK1R) and synthesize its agonists d The NK1R and its agonists co-localize in or near the T cell: APC immune synapse d The NK1R promotes optimal Ca 2+ flux and survival of TCRactivated T cells d Lack of the NK1R or its agonists results in deficient Th1-/ Th17-biased immunity Authors

1. A number of strategies that divert attacks of visually guided predators, such as birds, have evolved multiple times in animals. Detritus web decorations built by certain orb-web spider species are thought to deflect avian predator attacks away from spiders and towards their web decorations. Still, empirical evidence for this function and its adaptive significance is lacking. The orb-web spider, Cyclosa monticola, adorns its web using a linear detritus decoration consisting of moults, egg sacs, prey remains and leaf litters. 2. In the present study, we investigated whether detritus decorations constructed by C. monticola spiders divert attacks of avian predators away from spiders. We first employed colour modelling to compare spider bodies and detritus decoration colouration from the perspective of domestic chicks and blue tits. We then experimentally tested the deflection hypothesis in the laboratory using naïve chicks as predators. We put the chicks in a cage containing a web either with (S+) or without (S−) a spider and either with (D+) or without (D−) detritus decoration (a total of four types of webs: S+D+, S+D−, S−D+ and S−D−) under both natural habitat background and white background. 3. We found that the colour of C. monticola spiders is indistinguishable from that of their detritus decorations for both chicks and blue tits with both backgrounds. Laboratory predation experiments showed that with both backgrounds, chicks attacked the spiders much less frequently when their decorations were present on the webs (S+D+; natural habitat: 20%, white background: 30%) than when their decorations were absent (S+D−; natural habitat: 95%, white background: 85%), resulting in greater spider survival advantage. 4. We also found that the rate of attack of spiders and their decorations was not random; the decorations were more likely to be attacked than spiders, regardless of the ratio of surface area of decorations to spider bodies when both spiders and decorations were presented (S+D+). Therefore, our results support a deflection, rather than concealment hypothesis for web decorations. | 2111 Functional Ecology MA et Al.

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