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Yanagida T, Nakayama K, Sawada T, Honjo M, Murakami S, Iida T, Hirose E, Kitamura SI. Innate immunity in the edible ascidian Halocynthia roretzi developing soft tunic syndrome: Hemolymph can eliminate the causative flagellates and discriminate allogeneic hemocytes. FISH & SHELLFISH IMMUNOLOGY 2022; 127:659-665. [PMID: 35779813 DOI: 10.1016/j.fsi.2022.06.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/16/2022] [Accepted: 06/21/2022] [Indexed: 06/15/2023]
Abstract
The infection of the kinetoplastid flagellate Azumiobodo hoyamushi causes soft tunic syndrome that often results in mass mortality in the aquaculture of the edible ascidian Halocynthia roretzi. In the diseased ascidian individuals, the flagellates are exclusively found in the tunic matrix that entirely cover the epidermis, and never invade into internal tissues, such as a mantle. The present study for the first time demonstrated that the ascidian blood plasma and hemolymph have an activity to agglutinate and disintegrate the flagellates, suggesting the innate immunity protects the internal tissue from the invasion of A. hoyamushi. This activity is indifferent between the healthy and the diseased individuals. Allo-specific recognition and cytotoxic reaction among ascidian hemocytes, so-called contact reaction, occur among the individuals of healthy-healthy, healthy-diseased, and diseased-diseased combination, and therefore, the hemocytes from diseased individuals still retain the allo-reactivity. Moreover, the allo-reactive combinations are not changed under the presence of the flagellates, indicating the flagellates neither suppress nor induce the effector system of the contact reaction. These results suggest that the infection of A. hoyamushi does not impair the innate immunity in the ascidian hemolymph.
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Affiliation(s)
- Tetsuya Yanagida
- Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, 753-8515, Japan
| | - Kei Nakayama
- Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Ehime, 790-8577, Japan
| | - Tomoo Sawada
- Graduate School of Medicine, Yamaguchi University, Ube, Yamaguchi, 755-8505, Japan
| | - Miho Honjo
- Miyagi Prefecture Fisheries Technology Institute, Ishinomaki, Miyagi, 986-2135, Japan
| | - Shoko Murakami
- Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Ehime, 790-8577, Japan
| | - Takaji Iida
- Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime, 794-8555, Japan
| | - Euichi Hirose
- Department of Chemistry, Biology, and Marine Science, Faculty of Science, University of the Ryukyus, Okinawa, 903-0213, Japan
| | - Shin-Ichi Kitamura
- Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Ehime, 790-8577, Japan.
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Melillo D, Marino R, Della Camera G, Italiani P, Boraschi D. Assessing Immunological Memory in the Solitary Ascidian Ciona robusta. Front Immunol 2019; 10:1977. [PMID: 31475017 PMCID: PMC6707023 DOI: 10.3389/fimmu.2019.01977] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 08/05/2019] [Indexed: 11/13/2022] Open
Abstract
The immune defensive mechanisms active in the solitary ascidian Ciona robusta include phagocytic and encapsulating activity, largely brought about by phagocytic cells within the haemocyte population, the presence of complement components, which have been molecularly and functionally identified, and expression of a number of immune-related genes and pathways, identified by genome-based homology with vertebrate counterparts. Since C. robusta only displays highly conserved innate immune mechanisms, being devoid of an adaptive immune system, this organism is an excellent model for studying the features of innate memory, i.e., the capacity of the innate immune system to re-programming its responsiveness to potentially dangerous agents upon repeated exposure. In this study, we have developed an in vivo model for assessing the establishment and molecular/functional features of innate memory, by sequentially exposing C. robusta to a priming stimulus (microbial molecules), followed by a period of resting to return to basal conditions, and a challenge with microbial agents in homologous or cross-stimulation. The endpoints of immune activation were a functional activity (phagocytosis) and the molecular profiles of immune-related gene expression. The results show that exposure of C. robusta to microbial agents induces a reaction that primes animals for developing a different (expectedly more protective) response to subsequent challenges, showing the effective establishment of an immune memory. This immune memory relies on the modulation of a number of different mechanisms, some of which are priming-specific, others that are challenge-specific, and others that are non-specific, i.e., are common to all priming/challenge combinations (e.g., up-regulation of the Tnf and Lbp genes). Memory-dependent expression of the humoral immunity-related gene C3ar inversely correlates with memory-dependent variations of phagocytic rate, suggesting that complement activation and phagocytosis are alternative defensive mechanisms in C. robusta. Conversely, memory-dependent expression of the cellular immunity-related gene Cd36 directly correlates with variations of phagocytic rate, suggesting a direct involvement of this gene in the functional regulation of phagocytosis.
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Affiliation(s)
- Daniela Melillo
- National Research Council (CNR), Institute of Biochemistry and Cell Biology (IBBC), Naples, Italy
| | - Rita Marino
- Biology and Evolution of Marine Organisms (BEOM), Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Giacomo Della Camera
- National Research Council (CNR), Institute of Biochemistry and Cell Biology (IBBC), Naples, Italy
| | - Paola Italiani
- National Research Council (CNR), Institute of Biochemistry and Cell Biology (IBBC), Naples, Italy
| | - Diana Boraschi
- National Research Council (CNR), Institute of Biochemistry and Cell Biology (IBBC), Naples, Italy.,Biology and Evolution of Marine Organisms (BEOM), Stazione Zoologica Anton Dohrn, Naples, Italy
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Franchi N, Ballarin L. Immunity in Protochordates: The Tunicate Perspective. Front Immunol 2017; 8:674. [PMID: 28649250 PMCID: PMC5465252 DOI: 10.3389/fimmu.2017.00674] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 05/24/2017] [Indexed: 11/13/2022] Open
Abstract
Tunicates are the closest relatives of vertebrates, and their peculiar phylogenetic position explains the increasing interest toward tunicate immunobiology. They are filter-feeding organisms, and this greatly influences their defense strategies. The majority of the studies on tunicate immunity were carried out in ascidians. The tunic acts as a first barrier against pathogens and parasites. In addition, the oral siphon and the pharynx represent two major, highly vascularized, immune organs, where circulating hemocytes can sense non-self material and trigger immune responses that, usually, lead to inflammation and phagocytosis. Inflammation involves the recruitment of circulating cytotoxic, phenoloxidase (PO)-containing cells in the infected area, where they degranulate as a consequence of non-self recognition and release cytokines, complement factors, and the enzyme PO. The latter, acting on polyphenol substrata, produces cytotoxic quinones, which polymerize to melanin, and reactive oxygen species, which induce oxidative stress. Both the alternative and the lectin pathways of complement activation converge to activate C3: C3a and C3b are involved in the recruitment of hemocytes and in the opsonization of foreign materials, respectively. The interaction of circulating professional phagocytes with potentially pathogenic foreign material can be direct or mediated by opsonins, either complement dependent or complement independent. Together with cytotoxic cells, phagocytes are active in the encapsulation of large materials. Cells involved in immune responses, collectively called immunocytes, represent a large fraction of hemocytes, and the presence of a cross talk between cytotoxic cells and phagocytes, mediated by secreted humoral factors, was reported. Lectins play a pivotal role as pattern-recognition receptors and opsonizing agents. In addition, variable region-containing chitin-binding proteins, identified in the solitary ascidian Ciona intestinalis, control the settlement and colonization of bacteria in the gut.
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Affiliation(s)
- Nicola Franchi
- Department of Biology, University of Padova, Padova, Italy
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Abstract
Invertebrate animals, which lack adaptive immune systems, have developed other systems of biological host defense, so called innate immunity, that respond to common antigens on the cell surfaces of potential pathogens. During the past two decades, the molecular structures and functions of various defense components that participated in innate immune systems have been established in Arthropoda, such as, insects, the horseshoe crab, freshwater crayfish, and the protochordata ascidian. These defense molecules include phenoloxidases, clotting factors, complement factors, lectins, protease inhibitors, antimicrobial peptides, Toll receptors, and other humoral factors found mainly in hemolymph plasma and hemocytes. These components, which together compose the innate immune system, defend invertebrate from invading bacterial, fungal, and viral pathogens. This review describes the present status of our knowledge concerning such defensive molecules in invertebrates.
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Affiliation(s)
- Sadaaki Iwanaga
- The Chemo-Sero-Therapeutic Research Institute, Okubo 1-6-1, Kumamoto 860-8568, Japan
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Shida K, Terajima D, Uchino R, Ikawa S, Ikeda M, Asano K, Watanabe T, Azumi K, Nonaka M, Satou Y, Satoh N, Satake M, Kawazoe Y, Kasuya A. Hemocytes of Ciona intestinalis express multiple genes involved in innate immune host defense. Biochem Biophys Res Commun 2003; 302:207-18. [PMID: 12604333 DOI: 10.1016/s0006-291x(03)00113-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Ascidians, which are classified as urochordata, appear to employ a primitive system of host defense that is considered to be a prototype of vertebrate innate immunity. We performed a cDNA/EST study to identify the genes expressed in the hemocytes of Ciona intestinalis. We obtained 3357 one-path reads that were then grouped into 1889 independent clusters. Although two thirds of the clusters could not be assigned to any particular gene, the remaining 530 clusters had significant homology to genes with known function. Of these, 62 clusters appeared to be related to host defense mechanisms. These include transcripts whose products are probably involved in cytotoxicity, detoxification, inflammation, and apoptosis. As expected, elements of acquired immunity were not detected. Thus, Ciona hemocytes appear to express a number of host defense-related genes involved in innate immune mechanisms.
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Affiliation(s)
- Kazuhito Shida
- Center for Interdisciplinary Research, Tohoku University, Sendai, Japan
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Sekine H, Kenjo A, Azumi K, Ohi G, Takahashi M, Kasukawa R, Ichikawa N, Nakata M, Mizuochi T, Matsushita M, Endo Y, Fujita T. An ancient lectin-dependent complement system in an ascidian: novel lectin isolated from the plasma of the solitary ascidian, Halocynthia roretzi. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:4504-10. [PMID: 11591777 DOI: 10.4049/jimmunol.167.8.4504] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mannose-binding lectin (MBL) is a C-type lectin involved in the first line of host defense against pathogens and it requires MBL-associated serine protease (MASP) for activation of the complement lectin pathway. To elucidate the origin and evolution of MBL, MBL-like lectin was isolated from the plasma of a urochordate, the solitary ascidian Halocynthia roretzi, using affinity chromatography on a yeast mannan-Sepharose. SDS-PAGE of the eluted proteins revealed a major band of approximately 36 kDa (p36). p36 cDNA was cloned from an ascidian hepatopancreas cDNA library. Sequence analysis revealed that the carboxy-terminal half of the ascidian lectin contains a carbohydrate recognition domain (CRD) that is homologous to C-type lectin, but it lacks a collagen-like domain that is present in mammalian MBLs. Purified p36 binds specifically to glucose but not to mannose or N-acetylglucosamine, and it was designated glucose-binding lectin (GBL). The two ascidian MASPs associated with GBL activate ascidian C3, which had been reported to act as an opsonin. The removal of GBL-MASPs complex from ascidian plasma using Ab against GBL inhibits C3-dependent phagocytosis. These observations strongly suggest that GBL acts as a recognition molecule and that the primitive complement system, consisting of the lectin-proteases complex and C3, played a major role in innate immunity before the evolution of an adaptive immune system in vertebrates.
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Affiliation(s)
- H Sekine
- Department of Biochemistry and Internal Medicine II, Fukushima Medical University School of Medicine, Fukushima, Japan
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