Is there a direct role for erythrocytes in the immune response?

Erythrocytes are highly abundant circulating cells in the vertebrates, which, with the notable exception of mammals, remain nucleated throughout the entire life cycle. The major function associated with these cells is respiratory gas exchange however other functions including interaction with the immune system have been attributed to these cells. Many viral, prokaryotic and eukaryotic pathogens directly target this cell type and across the vertebrate group a significant number of related pathologies have been reported. Across the primary literature mechanisms of interaction, invasion and replication between viruses and erythrocytes have been well described however the functional response of the erythrocyte has been poorly studied. A fragmented series of reports spanning the vertebrates suggests that these cells are capable of functional responses to viral infection. In contrast, in-depth proteomic studies using human erythrocytes have strongly progressed throughout the past decade providing a rich source of information related to protein expression and potential function. Furthermore information at the gene expression level is becoming available. Here we provide a review of erythrocyte-pathogen interactions, erythrocyte functions in immunity and propose in light of recent -omics research that the nucleated erythrocytes may have a direct role in the immune response

Cortisol: funcions i importància del receptor glucocorticoide : una visió comparada

Les hormones corticoesteroides són essencials per a la regulació d'una gran varietat de processos fisiològics. El cortisol és el principal corticoesteroide en peixos teleostis, amb funcions glucocorticoides i mineralocorticoides. És el principal indicador de la resposta a l'estrès, i la principal hormona en el control de l'osmorregulació en peixos, especialment per a l'adaptació a l'aigua marina. També intervé en la regulació de la resposta inflamatòria inhibint la producció de citocines després d'una infecció experimental per l'endotoxina dels bacteris gramnegatius o LPS. Una infecció experimental per LPS desencadena una reacció immunitària innata que activa una resposta inflamatòria. Les citocines produïdes en resposta a aquesta infecció activen l'eix hipotalàmic-pituïtari-interrenal (HPI) mitjançant l'activació de l'hormona adrenocorticotropa (ACTH) i l'alliberació de cortisol. També, els efectes de les hormones corticoesteroides estan regulats a través de receptors intracell. ulars específics que actuen com a factors de transcripció dependents del lligand i activen diferents gens implicats en la resposta a l'estrès. Aquests receptors són el receptor de tipus i o receptor mineralocorticoide (MR) i el receptor de tipus ii o receptor glucocorticoide (GR). Per tant, la comunicació neuroimmunoendocrina en els vertebrats és crucial per a mantenir l'homeòstasi i el receptor de cortisol hi té un paper clau.Corticosteroid hormones are essential for the regulation of a wide variety of physiological processes. Cortisol is the most important corticoesteroid in teleost fish, with glucocorticoid and mineralocorticoid functions. It is the principal indicator of stress response, and it is the main hormone in osmoregulation in fish, especially in seawater adaptation. It also participates in the regulation of the inflammatory response inhibiting the production of cytokines after an immune challenge by the endotoxin of gramnegative bacteria or LPS. An experimental infection by LPS unleash an innate immune reaction that activates an inflamatory response. The cytokines produced in response to exposure to LPS are also involved in the activation of the hypothalamic-pituitary-interrenal axis (HPI) through the activation of the adrenocorticotropin hormone (ACTH) and the cortisol release. On the other hand, the effects of corticosteroid hormones are mediated through intracellular receptors that act as ligand-dependant transcription factors and activate different genes involve in the stress response. These receptors are the receptor type I or mineralocorticoid receptor (MR) and the receptor type II or glucocorticoid receptor (GR). Therefore, the neuro-immune-endocrine comunication in vertebrates is crucial to maintain the homeostasis and the cortisol receptor plays a key role

Fish health challenge after stress : indicators of immunocompetence

Changes in the nervous and endocrine systems of fish after stress episodes have consequences on their immune system and thereby affect the ability to maintain immunocompetence. Fish mainly depend upon innate immune responses, which include a rich and powerful array of mechanisms, that appear to be more potent than in higher vertebrates. Thus, fish provide a unique model to understand the evolution of immune defence system. When the organism is challenged by an antigen or by stressors, a number of responses of reactive nature are engaged in an attempt to counteract the threat and recover homeostasis. However, if the challenge is maintained, changes in the immune system become chronic, and suppression can be observed in several key immune mechanisms, leading to maladaptation. Therefore, the time factor is of key importance in immune assessment. Taking into account this dynamic pattern of infection and stress, specific indicators should be identified in order to detect functional changes in the immune system. Furthermore, there is a need for specific markers that reflect either activation in the initial stages or suppression in response to a chronic challenge.Els canvis en els sistemes nerviós i endocrí després d'episodis d'estrès generen conseqüències en el sistema immunitari que influeixen en la capacitat de mantenir la immunocompetència. Els peixos depenen especialment de la resposta immunitària innata, un ampli conjunt de mecanismes que sembla que actuïn amb més potència que en vertebrats superiors. Així, els peixos es troben en una posició evolutiva única per a comprendre els models de mecanismes de defensa en els vertebrats. Quan l'organisme és afectat per un antigen o per situacions que provoquen estrès, s'inicien una sèrie de respostes de naturalesa reactiva per a contrarestar-ne els efectes i recobrar l'homeòstasi. Altrament, els canvis en el sistema immunitari esdevenen crònics i es pot observar una depressió en alguns mecanismes immunitaris que acaben amb una mala adaptació. Per tant, el factor temps és clau en la determinació de la resposta immunitària. Tenint en compte aquest patró dinàmic en la infecció i l'estrès, és important determinar indicadors específics que detectin canvis funcionals del sistema immunitari dels peixos. Els marcadors més apropiats són els que indiquen tant una activació dels mecanismes immunitaris en els estadis inicials com una depressió en situacions cròniques

Conseqüències fisiològiques d'una activació del sistema immunitari sobre la reproducció i el creixement en peixos d'interès en aqüicultura

En peixos teleostis, una activació del sistema immunitari comporta la producció de factors immunitaris que ajuden a combatre una infecció i estableixen una comunicació entre la resposta immunitària innata i l'adaptativa. A part d'aquesta funció estrictament immunitària, els factors immunitaris poden afectar el funcionament d'altres cèl·lules i teixits no immunitaris. Dos processos particularment importants, tant per l'estat biològic d'una població de peixos, com per aspectes més relacionats amb la productivitat d'espècies en cultiu, són la reproducció i el creixement. En aquest treball es descriuen estudis encaminats a investigar els efectes d'una activació del sistema immunitari, i dels factors produïts, sobre la reproducció i el creixement en peixos teleostis.In teleost fish, an activation of the immune system entails the production of immune factors that are key to fighting an infeccion and establish a bridge between the innate and D’aquesthe adaptive immune responses. In addition to this strictly immune function, immune factors can also affect the function of other non-immune cells and tissues. Reproduction and growth are two processes that are particularly important for the biological condition of a population of fish as well as for aspects more related to productivity of cultured species. In this paper, we describe studies designed to investigate the effects of an activation of the immune system, as well as of the factors produced, on reproduction and growth in teleost fish

Fish can show emotional fever: stress-induced hyperthermia in zebrafish

Whether fishes are sentient beings remains an unresolved and controversial question. Among characteristics thought to reflect a low level of sentience in fishes is an inability to show stress-induced hyperthermia (SIH), a transient rise in body temperature shown in response to a variety of stressors. This is a real fever response, so is often referred to as ‘emotional fever’. It has been suggested that the capacity for emotional fever evolved only in amniotes (mammals, birds and reptiles), in association with the evolution of consciousness in these groups. According to this view, lack of emotional fever in fishes reflects a lack of consciousness. We report here on a study in which six zebrafish groups with access to a temperature gradient were either left as undisturbed controls or subjected to a short period of confinement. The results were striking: compared to controls, stressed zebrafish spent significantly more time at higher temperatures, achieving an estimated rise in body temperature of about 2–4°C. Thus, zebrafish clearly have the capacity to show emotional fever. While the link between emotion and consciousness is still debated, this finding removes a key argument for lack of consciousness in fishes

A Novel Liposome-Based Nanocarrier Loaded with an LPS-dsRNA Cocktail for Fish Innate Immune System Stimulation

Development of novel systems of vaccine delivery is a growing demand of the aquaculture industry. Nano- and micro- encapsulation systems are promising tools to achieve efficient vaccines against orphan vaccine fish diseases. In this context, the use of liposomal based-nanocarriers has been poorly explored in fish; although liposomal nanocarriers have successfully been used in other species. Here, we report a new ~125 nm-in-diameter unilamellar liposome-encapsulated immunostimulant cocktail containing crude lipopolysaccharide (LPS) from E. coli and polyinosinic:polycytidylic acid [poly (I:C)], a synthetic analog of dsRNA virus, aiming to be used as a non-specific vaccine nanocarrier in different fish species. This liposomal carrier showed high encapsulation efficiencies and low toxicity not only in vitro using three different cellular models but also in vivo using zebrafish embryos and larvae. We showed that such liposomal LPS-dsRNA cocktail is able to enter into contact with zebrafish hepatocytes (ZFL cell line) and trout macrophage plasma membranes, being preferentially internalized through caveolae-dependent endocytosis, although clathrin-mediated endocytosis in ZFL cells and macropinocytocis in macrophages also contribute to liposome uptake. Importantly, we also demonstrated that this liposomal LPS-dsRNA cocktail elicits a specific pro-inflammatory and anti-viral response in both zebrafish hepatocytes and trout macrophages. The design of a unique delivery system with the ability to stimulate two potent innate immunity pathways virtually present in all fish species represents a completely new approach in fish health

Situationally edited empathy: an effect of socio-economic structure on individual choice

Criminological theory still operates with deficient models of the offender as agent, and of social influences on the agent’s decision-making process. This paper takes one ‘emotion’, empathy, which is theoretically of considerable importance in influencing the choices made by agents; particularly those involving criminal or otherwise harmful action. Using a framework not of rational action, but of ‘rationalised action’, the paper considers some of the effects on individual psychology of social, economic, political and cultural structure. It is suggested that the climate-setting effects of these structures promote normative definitions of social situations which allow unempathic, harmful action to be rationalised through the situational editing of empathy. The ‘crime is normal’ argument can therefore be extended to include the recognition that the uncompassionate state of mind of the criminal actor is a reflection of the self-interested values which govern non-criminal action in wider society