Innate Immunity (original) (raw)

The innate and adaptive immune system of fish

Infectious Disease in Aquaculture, 2012

This chapter describes what is known about the main components and responses of the innate and adaptive immune system of fi sh. The chapter fi rst reviews the organs, cells and molecules of the immune system known in a few economically important or model fi sh species. Molecular evidence suggests a similar immune system exists throughout the jawed vertebrates yet marked differences are also apparent. The innate parameters are at the forefront of fi sh immune defence and are a crucial factor in disease resistance. The adaptive response of fi sh is commonly delayed but is essential for long lasting immunity and a key factor in successful vaccination.

[PDF]Fish immune system. A crossroads between innate and

Considerados como la base evolutiva vertebrada tras su radiación adaptativa en el Devónico, los peces constituyen en la actualidad el grupo más exitoso y diversificado de vertebrados. Como grupo, este conjunto heterogéneo de organismos representa una aparente encrucijada entre la respuesta inmunitaria innata y la aparición de una respuesta inmunitaria adaptativa. La mayoría de órganos inmunitarios de los mamíferos tienen sus homólogos en los peces. Sin embargo, su eventual menor complejidad estructural podría potencialmente limitar la capacidad para generar una respuesta inmunitaria completamente funcional frente a la invasión de patógenos. Se discute aquí la capacidad de los peces para generar respuestas inmunitarias exitosas, teniendo en cuenta la robustez aparente de la respuesta innata de los peces, en comparación con la observada en vertebrados superiores.

Main Components of Fish Immunity: An Overview of the Fish Immune System

Fishes

Cellular immune responses consist of innate and adaptive cell-mediated immune mechanisms, where all leukocyte subpopulations are included. Among these are vital processes such as cell-mediated cytotoxicity and phagocytosis. The main cellular constituents of the fish immune system are macrophages, granulocytes, dendritic cells, NK cells, and cytotoxic T cells. This review provides the latest information on cellular defense mechanisms of fish and provides an overview of the function of the mucosal immune system in maintaining the general health of fish. Here, we discuss the fundamental ideas that underpin mucosal immune responses in teleosts, as well as the innate and adaptive immune cells and the molecules that play a role in these immune responses. Moreover, cytokine molecules and pathways in teleosts have been reported to focus on several kinds of associated immunity. Importantly, we also review antigen processing and presentation. The knowledge reported here will enable better und...

Major components of fish immunity: a review

2016

Fish are fascinating creatures with a certain degree of immunity comparable to those of mammals. The fish's immune system consists of two major components, innate and adaptive immunities. Innate immunity is non-specific and acts as the primary line of protection against pathogen invasion while adaptive immunity is more specific to a certain pathogen/following adaptation. Innate immunity consists of the non-specific cellular and the non-specific humoral components. The non-specific cellular component consists of toll-like receptors (TLRs), macrophages, neutrophils, eosinophils and non-specific cytotoxic cell while the non-specific humoral component involves lysozyme, the complement, interferons, C-reactive proteins, transferrins and lectins. They work together at the initial stage to prevent pathogen invasion. On the other hand, the adaptive immune system consists of highly specilised systemic cells and processes that are separated into two main components: the humoral and cellul...

Under control: The innate immunity of fish from the inhibitors' perspective

Fish & Shellfish Immunology

The innate immune response involves a concerted network of induced gene products, preformed immune effectors, biochemical signalling cascades and specialised cells. However, the multifaceted activation of these defensive measures can derail or overshoot and, if left unchecked, overwhelm the host. A plenty of regulatory devices therefore mediate the fragile equilibrium between pathogen defence and pathophysiological manifestations. Over the past decade in particular, an almost complete set of teleostean sequences orthologous to mammalian immunoregulatory factors has been identified in various fish species, which prove the remarkable conservation of innate immune-control concepts among vertebrates. This review will present the current knowledge on more than 50 teleostean regulatory factors (plus additional fish-specific paralogs) that are of paramount importance for controlling the clotting cascade, the complement system, pattern-recognition pathways and cytokine-signalling networks. A special focus lies on those immunoregulatory features that have emerged as potential biomarker genes in transcriptome-wide research studies. Moreover, we report on the latest progress in elucidating control elements that act directly with immune-gene-encoding nucleic acids, such as transcription factors, hormone receptors and micro-and long noncoding RNAs. Investigations into the function of teleostean inhibitory factors are still mainly based on gene-expression profiling or overexpression studies. However, in support of structural and in-vitro analyses, evidence from in-vivo trials is also available and revealed many biochemical details on piscine immune regulation. The presence of multiple gene copies in fish adds a degree of complexity, as it is so far hardly understood if they might play distinct roles during inflammation. The present review addresses this and other open questions that should be tackled by fish immunologists in future.

The cytokine networks of adaptive immunity in fish

Fish & Shellfish Immunology, 2013

Cytokines, produced at the site of entry of a pathogen, drive inflammatory signals that regulate the capacity of resident and newly arrived phagocytes to destroy the invading pathogen. They also regulate antigen presenting cells (APCs), and their migration to lymph nodes to initiate the adaptive immune response. When naive CD4þ T cells recognize a foreign antigen-derived peptide presented in the context of major histocompatibility complex class II on APCs, they undergo massive proliferation and differentiation into at least four different T-helper (Th) cell subsets (Th1, Th2, Th17, and induced T-regulatory (iTreg) cells in mammals. Each cell subset expresses a unique set of signature cytokines. The profile and magnitude of cytokines produced in response to invasion of a foreign organism or to other danger signals by activated CD4þ T cells themselves, and/or other cell types during the course of differentiation, define to a large extent whether subsequent immune responses will have beneficial or detrimental effects to the host. The major players of the cytokine network of adaptive immunity in fish are described in this review with a focus on the salmonid cytokine network. We highlight the molecular, and increasing cellular, evidence for the existence of T-helper cells in fish. Whether these cells will match exactly to the mammalian paradigm remains to be seen, but the early evidence suggests that there will be many similarities to known subsets. Alternative or additional Th populations may also exist in fish, perhaps influenced by the types of pathogen encountered by a particular species and/or fish group. These Th cells are crucial for eliciting disease resistance post-vaccination, and hopefully will help resolve some of the difficulties in producing efficacious vaccines to certain fish diseases.

Immune System of Fish: An Evolutionary Perspective

Antimicrobial Immune Response

Fishes are the most successful and diverse group of vertebrate animals, first appeared during Devonian period. Despite of certain differences, the immune system of fish is physiologically similar to that of higher vertebrates. The heterogenous group of fishes are the apparent link between innate immunity and the first appearance of the adaptive immune response. Importantly, fishes have immune organs homologous to that of mammalian immune system. In comparison to higher vertebrates, fishes live free in their environment from the early embryonic stage and during that time mostly they are dependent on non-specific immune system for their survival. In the fishes, non-specific immunity is the fundamental defense mechanism, therewith acquired immunity also plays key role in maintaining homeostasis by activation though a system of receptors proteins, which identify pathogen associated molecular pattern typical of pathogenic microorganism includes lipopolysaccharides, peptidoglycans, DNA, R...