Main Components of Fish Immunity - Innate Immune System & Antigen Processing and Presentation

 

@어류면역체계.pdf

0.74MB

 

 

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.

 

cell-mediated immune 세포 매개 면역

leukocyte subpopulations 림프구 하위집단

vital 필수적인

cell-mediated cytotoxicity 세포매개세포독성

phagocytosis 식세포 활동

 

The main cellular constituents of the fish immune system are macrophages, granulocytes, dendritic cells, NK cells, and cytotoxic T cells.

 

cellular constituents 세포 내용물질

granulocytes 과립구

 

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.

 

mucosal immune system 점막 면역계

 

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.

 

fundamental 근본적인

underpin (주장 등을)뒷받침하다[근거를 대다]

teleost 경골의

 

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 understanding, determination, and modulation of the pathways responsible for protective immunity, thus consequently improving the health of the fish in aquaculture.

 

determination 확인

consequently 그 결과, 따라서

 

1. Introduction

The innate immune system and the adaptive immune system are the two components of the vertebrate immune system.

 

vertebrate 척추동물

 

Initial infections and diseases are first addressed by the innate immune system. Innate immune system components include physical barriers, cellular processes, and humoral components [1].

 

 

With the persistence of the pathogen, the adaptive immune system entices the pathogen with specificity and memory.

 

persistence (없어지지 않고 오래 동안)지속됨

entice 유도하다

 

The adaptive immune system is highly specific to a specific antigen and can provide long-standing immunity [2].

 

 

Several ingredients of the adaptive system, including T cell receptors (TCR), immunoglobulins (Igs), and major histocompatibility complex (MHC), are presumed to have arisen in the first jawed vertebrates [3].

 

ingredients 구성요소

presumed 추정하다

arise 유발되다

jawed vertebrates 유악류

 

Physiologically, the immune systems of fish and higher vertebrates are similar. In contrast to higher vertebrates, fish are mostly dependent on non-specific immune systems during their survival in the environment from the early embryonic stage.

 

Physiologically 생리학적으로

vertebrates 척추동물

In contrast to ~와는 대조적으로

embryonic stage 배아기

 

The innate immunity acts by identifying pathogen-associated molecular patterns of pathogenic microorganisms, while the acquired immunity acts through antigen-specific receptors [4].

 

identifying 감별

pathogenic microorganisms 병원미생물

 

In the teleost immune system, antigens are handled and presented by a wide variety of accessory or antigen-presenting cells (APC), including macrophages or monocytes, to specific lymphocytes in a seemingly alloantigen-restricted fashion [5].

 

seemingly 외견상으로

alloantigen 동종 항원

An alloantigen is an antigen that is present in a portion of the population and absent in the rest of that population. 집단의 일부에는 존재하지만 나머지 집단에는 존재하지 않는 항원

restricted fashion 제한된 방식

 

Jawed vertebrate species are distinguished by their adaptive immune system, which is based on B and T cells, along with high degrees of diversity and specificity of their antigen receptors, the immunoglobulins (IG) or antibodies and the T cell receptors (TCRs), respectively [6].

 

distinguished 유명한

respectively 각각

 

Teleost antibodies are found in the skin, intestine, bile, gill mucus, and systemically in the plasma [7–10]. Furthermore, specific antibodies can be generated in these regions without generating a systemic response [9,11,12].

 

bile 담즙

mucus 점액

systemically 조직적으로

 

Previous studies and reviews have reported the existence of all major cytokine families in fish [13–16]. IL-1β and TNF-α are cytokines implicated in inflammatory response induction in fish.

 

implicated 연루되다

inflammatory response 염증반응

 

Moreover, IL-6 has been reported to be involved in the cascade that induces an inflammatory response [17]. Furthermore, cytokines involved in leukocyte differentiation have been identified in fish [18,19].

 

involve 관련시키다

inflammatory response 염증반응

differentiation 분화

 

This review provides a background to the immune system of fish, describes the main parameters of the innate and adaptive immune systems, and highlights recent knowledge on the immune components in teleost fish.

 

describes 묘사하다

parameter 한도

 

2. Innate Immune System

Physiologically, the fish and higher vertebrate immune systems are similar, with certain differences, as fish are free-living organisms that depend on the innate immune system for their survival from the early embryonic stages of life [20].

 

Physiologically 생리학적으로

embryonic stages 배아

 

 

The immune system of the fish is constituted by two immune mechanisms: innate (non-specific) and adaptive (specific). The components of the innate immunity respond to pathogens via identifying pathogen-associated molecular patterns (PAMPs) that demonstrate no expression in host cells.

 

constituted 구성된

identifying 감별

demonstrate 입증하다

expression 표현

 

Among these PAMPs recognized by the innate immune receptors are lipopolysaccharides (LPS), lipoteichoic acid (LTA), phospholipomannan, beta-glucan, chitin, and hemagglutinin [21–23]. Following pathogen recognition, the pathogens are destructed by phagocytosis, one of the effector mechanisms of innate immunity.

 

destruct 파괴하다

effector 반응기

 

However, adaptive immunity recognizes pathogens through highly specific receptors, and consequently induces specific B and T cell clone proliferation and differentiation [24]. In fish, the innate immunity is the primary defense line that shows reactions to pathogens within a very short time and does not provide long-standing protection [25].

 

consequently 그결과

proliferation 확산

differentiation 분화

 

In contrast to mammals, the fish innate immunity is an essential component in the prohibition of pathogen entry because of the inefficiency of the adaptive immune response [26]. Most of the primary and secondary lymphoid organs described in mammals are detected in fish, with the exception of the bone marrow and lymph nodes, which lack the organs’ complexity in fish compared to mammals.

 

In contrast to ~와는 대조적으로

prohibition 금지

inefficiency 비효율

lymphoid organs 림프기관

detect 탐지하다

with the exception of ~은 제외하고

complexity 복잡성

 

This results in a potential limitation and delays the generation of fully functional adaptive immune responses [27]. The immune system of teleost fish is constituted by two receptor categories: the antigen-specific receptors and germline-encoded pattern recognition receptors (PRRs).

 

 potential 가능성

limitation 한계

generation 세대

constitute ~을 구성하다

encoded 암호화된

 

Moreover, numerous other receptors or molecules can participate in the innate immunity. The innate mechanisms can be categorized into constitutive and inducible. The constitutive mechanism confers a quick response and rapid ongoing ligand binding to receptors, whereas the inducible mechanism acts slower, with a higher magnitude [28].

 

numerous 많은

the constitutive mechanism 

the inducible mechanism 

be categorized into ~로 분류되다

confer 수여하다

whereas 반면

magnitude 규모

 

 The constitutive mechanism

41577_2020_Article_391.pdf

2.66MB

 

the inducible mechanism 

weake2010.pdf

0.68MB

---

---

The innate immune system components in fish are generally categorized into three compartments: physical or surface, humoral, and cellular factors [29,30]. The physical or surface factors include scales, the mucus layer, and epithelial cells lining the gills, skin, and alimentary tract, providing a fundamental role in resisting infection [31–33]. 

 

scales 비늘

alimentary tract 소화관

 

Moreover, the epithelial cells of the epidermis prevent the entry of foreign materials, and are also populated with macrophages, eosinophilic granular cells, and lymphocytes [33,34]. The integrity of these cells plays a pivotal role in preserving the osmotic balance and eliminating microorganisms [35].

 

epidermis 표피

 populate 거주하다

eosinophilic granular cells 호산성 과립세포

 integrity 진실성

pivotal 중심이 되는

preserving 보존저장

osmotic 삼투의

eliminate 제거하다

 

Humoral immune parameters are an array of soluble substances, which have preemptive functions through the inhibition of the microorganism’s growth and neutralization of the enzymes on which the pathogen depends. Teleost fish contain many non-specific defense substances, including transferrin, lectins, lysozyme, antimicrobial peptides, cytokines, natural antibodies, and complement components, which can destroy microorganisms or suppress their growth [29,36].

 

Humoral immune 체액성 면역

parameter 한도

array 배열하다

soluble 가용성(녹는)

preemptive 선제의

inhibition 억제

 neutralization 중화

suppress 진압하다

 

Transferrin is an essential element for the growth of microorganisms and is an acute phase protein invoked during the inflammatory response process for removing iron from deteriorated tissue [37].

 

acute phase protein 급성기 단백질

https://metamedic.co.kr/content/634657ce571b5048b5e90787

invoked 적용된

inflammatory 염증을 일으키는

process 과정

deteriorate 악화되다

 

 It is also an activator of fish macrophages [38]. A wide variety of lytic enzymes may cause the lysis of pathogenic cells. These enzymes are either single or in combination. In fish, lysins include complement, lysozyme, and antimicrobial peptides. Lysozyme works on the peptidoglycan layer of bacterial cellular walls, causing bacterial lysis [39].

 

activator 활성제

 lytic enzymes 용해 효소

either A or B : A이거나 B인

 lysins 리신((아미노산의 일종))

 

Lysozymes are synthesized in the liver and extra hepatic sites, and are found in mucus, plasma, and lymphoid tissue. 

 

synthesized 합성화된

 

extra hepatic sites

The liver is so important in metabolism, the term extrahepatic has been defined to mean "located or occurring outside of the liver". We are next going to consider extrahepatic tissue metabolism.

https://med.libretexts.org/Bookshelves/Nutrition/Intermediate_Nutrition_(Lindshield)/07%3A_Integration_of_Macronutrient_Metabolism/7.03%3A_Extrahepatic_Macronutrient_and_Alcohol_Metabolism

 

They are involved in a comprehensive defense mechanism, such as bacteriolysis, in addition to restricted antiviral and antineoplastic activities [40].

 

 comprehensive 포괄적인

restricted 제한된

 antiviral  항바이러스성의

antineoplastic 항종양성의

 

Antimicrobial peptides play an essential role in host defense against viruses and bacteria. They are found in the mucus, liver tissue, and gills of teleosts [41,42]. 

 

The complement system plays a major role in the connection between both innate and adaptive immune responses, which permits an incorporated host defense to pathogenic challenges [43].

incorporate 포함하다

 pathogenic challenges 병원성 공격

 

This system serves diverse functions including mediation of inflammatory vasodilation, lysis of bacterial and infected cells, phagocytosis of foreign particles, and clearance of apoptotic cells. In many fish, the bactericidal activity of the complement system has been reported [44].

 

mediation 중재

inflammatory 염증을 일으키는

vasodilation 혈관 확장

phagocytosis 식균작용

clearance 없애기

 apoptotic cells 사멸세포

 

The cellular components of the fish’s innate immune system include a wide diversity of cells. These immune cells are activated when they recognize a pathogen via its PAMP, and, consequently, these cells can share in diverse responses, relying on their cell subtype [27].

 

3. Antigen Processing and Presentation

 

Antigen processing and presentation (APP) is defined as the process through which an antigenic protein is processed into peptides. These peptides are loaded and transferred to the cell surface on major histocompatibility complex (MHC) proteins [45].

 

Antigen Processing and Presentation 항원 처리 및 제시

 

Histocompatibility molecules are glycoprotein receptors that are expressed in all cells of an organism. They are encoded by a gene complex. MHC plays a vital role in exogenous and endogenous antigens [46].

 

glycoprotein 당단백

 exogenous and endogenous antigens

 

The adaptive immunity emergence is connected to the extremely polymorphic MHC genes encoding MHC, which are linked and scattered throughout a chromosomal genomic region in most jawed vertebrates, with varying levels of recombination. 

 

emergence 부상

extremely 극도로

polymorphic 다형의

scattered 드문드문 있는

throughout 동안 쭉

recombination 재조합

 

In teleost fish, the MHC class I gene family exists on several chromosomes; however, the MHC class II genes are missing in some fish species [47,48].

 

chromosomes 염색체

 

There is adequate evidence to confirm the similar functions of MHC class I and II molecules in fish and mammals [49]. The APP occurrence in teleost fish has been demonstrated through studies with the channel catfish (Ictalurus punctatus), with evidence revealing that MHC-like proteins govern the similar restricted APP to that observed in mammals [50], and with exogenous antigens being endocytosed by antigen-presenting cells (APCs) and inducing the proliferation of lymphocytes [51].

 

adequate 충분한

 demonstrate 입증하다

revealing 흥미로운 사실을 드러내는

govern 지배하다

restricted 제한된

 proliferation 급증

lymphocytes 림프구

 

All cells that express MHC class I and can implement APP are described as APC. The spleen and kidney are hematopoietic organs capable of prompting and exerting innate immune responses [30,52].

 

 implement 시행하다

hematopoietic organs 조혈계

 prompting 설득

exert 가하다

DOI: 10.5604/01.3001.0013.4535

 

In teleost, the spleen serves as a major secondary immune organ, and has a prime role in the antigen presentation and initiation of the adaptive immune response [26].

 

antigen presentation 항원제시

initiation 개시

 

Furthermore, the anterior kidney is the main immune organ accountable for antigen processing, phagocytosis, IgM, and immune memory formation through melanomacrophage centers [53–55].

 

 accountable 책임이 있는

antigen processing 항원처리

formation 형성

melanomacrophage 멜라닌 대식 세포

 

 

MHC class I molecule expression has been reported in teleost fish [56], and there is evidence indicating that the activation of CD8 + T lymphocyte-mediated cytotoxicity is MHC class I restricted [57], where MHC I molecules can reveal a cross-presentation process, through which these molecules can recognize and display exogenous antigens to cytotoxic T cells [58].

 

restricted 제한된

 

MHC class II is expressed only in the professional antigen-presenting cells (pAPCs), which mainly populate lymphoid organs including the head kidney, spleen, or thymus, and are capable of priming T lymphocytes to become cytotoxic CD8 + T lymphocytes or CD4 + T helper lymphocytes.

 

populate 거주하다

 priming 기폭제 

Furthermore, the pAPCs express MHC class II molecules that normally engulf pathogens, and display peptides processed from exogenous antigens via lysosomal pathways [59]. In some fish species, the pAPCs are B cells, dendritic cells (DCs), monocytes/macrophages, granulocytes, and erythrocytes [60–62].

 

 engulf 완전히 에워싸다

via ~를 통해

lysosomal pathways 리소좀 경로