Interleukin (IL)-2 Is a Key Regulator of T Helper 1 and T Helper 2 Cytokine Expression in Fish

Functional Characterization of Two Divergent IL2 Paralogs in Salmonids

Tiehui Wang, Yehfang Hu, Eakapol Wangkahart, Fuguo Liu, Alex Wang, Eman Zahran, Kevin Maisey, Min Liu, Qiaoqing Xu, Mónica Imarai, Christopher J Secombes

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Abstract

Mammalian interleukin (IL)-2 is a cytokine centrally involved in the differentiation and survival of CD4+ T helper subsets and CD4+ T regulatory cells and in activation of cytotoxic effector lymphocytes. In bony fish, IL2 orthologs have been identified with an additional divergent IL2-Like gene on the same locus present in several fish species. We report here two divergent IL2 paralogs, IL2A and IL2B, in salmonids that originated from the whole genome duplication event in this fish lineage. The salmonid IL2 paralogs differ not only in sequence but also in exon sizes. The IL-2 isoforms that are encoded have disparate pI values and may have evolved to preferentially bind specific IL-2 receptors. Rainbow trout IL2 paralogs are highly expressed in thymus, spleen, gills, kidney and intestine, important tissues/organs in fish T cell development and function. Their expression in peripheral blood leukocytes (PBL) is low constitutively but can be upregulated by the mixed leukocyte reaction, by the T cell mitogen phytohemagglutinin and by signal mimics of T cell activation (phorbol 12-myristate 13-acetate and calcium ionophore). Both trout IL-2 isoforms promoted PBL proliferation and sustained high-level expression of CD4 and CD8, suggesting that trout IL-2 isoforms are T cell growth/survival factors mainly expressed by activated T cells. The recombinant proteins for these two trout IL2 paralogs have been produced in E. coli and possess shared but also distinct bioactivities. IL-2A, but not IL-2B, induced IL12P35A1 and CXCR1 expression in PBL. IL-2B had a stronger effect on upregulation of the T helper 1 (Th1) cytokine interferon-γ (IFNγ) and could sustain CD8α and CD8β expression levels. Nevertheless, both cytokines upregulated key Th1 (IFNγ1, IFNγ2, TNFα2 and IL12) and T helper 2 (Th2) cytokines (IL4/13B1 and IL4/13B2), cytokine and chemokine receptors and the antimicrobial peptide cathelicidin-1 but had limited effects on T helper 17 cytokines and TGFβ1 in PBL. They could also enhance PBL phagocytosis. These results suggest, for the first time in fish, that IL-2 isoforms may have an important role in regulating Th1 and Th2 cell development, and innate and adaptive host defenses in fish, and shed light on lineage-specific expansion, evolution, and functional diversification of IL2 in vertebrates.
Original languageEnglish
Article number1683
JournalFrontiers in Immunology
Volume9
DOIs
Publication statusPublished - 26 Jul 2018

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Salmonidae
Interleukin-2
Fishes
Cytokines
Leukocytes
Trout
Interleukins
Protein Isoforms
T-Lymphocytes
Interleukin-4 Receptors
Th2 Cells
Mixed Lymphocyte Culture Test
Cytokine Receptors
Calcium Ionophores
Chemokine Receptors
Interleukin-2 Receptors
Oncorhynchus mykiss
Phytohemagglutinins
Regulatory T-Lymphocytes
Interleukin-12

Keywords

  • salmonids
  • interleukin-2
  • expression
  • bioactivity
  • T cell growth factor
  • T helper 1
  • T helper 2
  • phagocytosis

Cite this

Interleukin (IL)-2 Is a Key Regulator of T Helper 1 and T Helper 2 Cytokine Expression in Fish : Functional Characterization of Two Divergent IL2 Paralogs in Salmonids. / Wang, Tiehui; Hu, Yehfang; Wangkahart, Eakapol; Liu, Fuguo; Wang, Alex; Zahran, Eman; Maisey, Kevin; Liu, Min; Xu, Qiaoqing; Imarai, Mónica; Secombes, Christopher J.

In: Frontiers in Immunology, Vol. 9, 1683, 26.07.2018.

Research output: Contribution to journalArticle

Wang, Tiehui ; Hu, Yehfang ; Wangkahart, Eakapol ; Liu, Fuguo ; Wang, Alex ; Zahran, Eman ; Maisey, Kevin ; Liu, Min ; Xu, Qiaoqing ; Imarai, Mónica ; Secombes, Christopher J. / Interleukin (IL)-2 Is a Key Regulator of T Helper 1 and T Helper 2 Cytokine Expression in Fish : Functional Characterization of Two Divergent IL2 Paralogs in Salmonids. In: Frontiers in Immunology. 2018 ; Vol. 9.
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abstract = "Mammalian interleukin (IL)-2 is a cytokine centrally involved in the differentiation and survival of CD4+ T helper subsets and CD4+ T regulatory cells and in activation of cytotoxic effector lymphocytes. In bony fish, IL2 orthologs have been identified with an additional divergent IL2-Like gene on the same locus present in several fish species. We report here two divergent IL2 paralogs, IL2A and IL2B, in salmonids that originated from the whole genome duplication event in this fish lineage. The salmonid IL2 paralogs differ not only in sequence but also in exon sizes. The IL-2 isoforms that are encoded have disparate pI values and may have evolved to preferentially bind specific IL-2 receptors. Rainbow trout IL2 paralogs are highly expressed in thymus, spleen, gills, kidney and intestine, important tissues/organs in fish T cell development and function. Their expression in peripheral blood leukocytes (PBL) is low constitutively but can be upregulated by the mixed leukocyte reaction, by the T cell mitogen phytohemagglutinin and by signal mimics of T cell activation (phorbol 12-myristate 13-acetate and calcium ionophore). Both trout IL-2 isoforms promoted PBL proliferation and sustained high-level expression of CD4 and CD8, suggesting that trout IL-2 isoforms are T cell growth/survival factors mainly expressed by activated T cells. The recombinant proteins for these two trout IL2 paralogs have been produced in E. coli and possess shared but also distinct bioactivities. IL-2A, but not IL-2B, induced IL12P35A1 and CXCR1 expression in PBL. IL-2B had a stronger effect on upregulation of the T helper 1 (Th1) cytokine interferon-γ (IFNγ) and could sustain CD8α and CD8β expression levels. Nevertheless, both cytokines upregulated key Th1 (IFNγ1, IFNγ2, TNFα2 and IL12) and T helper 2 (Th2) cytokines (IL4/13B1 and IL4/13B2), cytokine and chemokine receptors and the antimicrobial peptide cathelicidin-1 but had limited effects on T helper 17 cytokines and TGFβ1 in PBL. They could also enhance PBL phagocytosis. These results suggest, for the first time in fish, that IL-2 isoforms may have an important role in regulating Th1 and Th2 cell development, and innate and adaptive host defenses in fish, and shed light on lineage-specific expansion, evolution, and functional diversification of IL2 in vertebrates.",
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T1 - Interleukin (IL)-2 Is a Key Regulator of T Helper 1 and T Helper 2 Cytokine Expression in Fish

T2 - Functional Characterization of Two Divergent IL2 Paralogs in Salmonids

AU - Wang, Tiehui

AU - Hu, Yehfang

AU - Wangkahart, Eakapol

AU - Liu, Fuguo

AU - Wang, Alex

AU - Zahran, Eman

AU - Maisey, Kevin

AU - Liu, Min

AU - Xu, Qiaoqing

AU - Imarai, Mónica

AU - Secombes, Christopher J

N1 - This work was funded by the Biotechnology and Biological Sciences Research Council (BBSRC, BB/N024052/1) under the Newton Fund RCUK-CONICYT Research Partnerships call. YH was supported by a PhD Studentship from the Ministry of Education, Republic of China (Taiwan). EW was supported financially by the Faculty of Technology, Mahasarakham University Grant Year 2018. FL was supported by a Newton International Fellowship funded by the Academy of Medical Sciences, UK (AMS, NIF004\1036). ML and QX were supported financially by the National Scholarship Council of China. This work was partially supported financially by European Commission contract No. 311993 (TargetFish).

PY - 2018/7/26

Y1 - 2018/7/26

N2 - Mammalian interleukin (IL)-2 is a cytokine centrally involved in the differentiation and survival of CD4+ T helper subsets and CD4+ T regulatory cells and in activation of cytotoxic effector lymphocytes. In bony fish, IL2 orthologs have been identified with an additional divergent IL2-Like gene on the same locus present in several fish species. We report here two divergent IL2 paralogs, IL2A and IL2B, in salmonids that originated from the whole genome duplication event in this fish lineage. The salmonid IL2 paralogs differ not only in sequence but also in exon sizes. The IL-2 isoforms that are encoded have disparate pI values and may have evolved to preferentially bind specific IL-2 receptors. Rainbow trout IL2 paralogs are highly expressed in thymus, spleen, gills, kidney and intestine, important tissues/organs in fish T cell development and function. Their expression in peripheral blood leukocytes (PBL) is low constitutively but can be upregulated by the mixed leukocyte reaction, by the T cell mitogen phytohemagglutinin and by signal mimics of T cell activation (phorbol 12-myristate 13-acetate and calcium ionophore). Both trout IL-2 isoforms promoted PBL proliferation and sustained high-level expression of CD4 and CD8, suggesting that trout IL-2 isoforms are T cell growth/survival factors mainly expressed by activated T cells. The recombinant proteins for these two trout IL2 paralogs have been produced in E. coli and possess shared but also distinct bioactivities. IL-2A, but not IL-2B, induced IL12P35A1 and CXCR1 expression in PBL. IL-2B had a stronger effect on upregulation of the T helper 1 (Th1) cytokine interferon-γ (IFNγ) and could sustain CD8α and CD8β expression levels. Nevertheless, both cytokines upregulated key Th1 (IFNγ1, IFNγ2, TNFα2 and IL12) and T helper 2 (Th2) cytokines (IL4/13B1 and IL4/13B2), cytokine and chemokine receptors and the antimicrobial peptide cathelicidin-1 but had limited effects on T helper 17 cytokines and TGFβ1 in PBL. They could also enhance PBL phagocytosis. These results suggest, for the first time in fish, that IL-2 isoforms may have an important role in regulating Th1 and Th2 cell development, and innate and adaptive host defenses in fish, and shed light on lineage-specific expansion, evolution, and functional diversification of IL2 in vertebrates.

AB - Mammalian interleukin (IL)-2 is a cytokine centrally involved in the differentiation and survival of CD4+ T helper subsets and CD4+ T regulatory cells and in activation of cytotoxic effector lymphocytes. In bony fish, IL2 orthologs have been identified with an additional divergent IL2-Like gene on the same locus present in several fish species. We report here two divergent IL2 paralogs, IL2A and IL2B, in salmonids that originated from the whole genome duplication event in this fish lineage. The salmonid IL2 paralogs differ not only in sequence but also in exon sizes. The IL-2 isoforms that are encoded have disparate pI values and may have evolved to preferentially bind specific IL-2 receptors. Rainbow trout IL2 paralogs are highly expressed in thymus, spleen, gills, kidney and intestine, important tissues/organs in fish T cell development and function. Their expression in peripheral blood leukocytes (PBL) is low constitutively but can be upregulated by the mixed leukocyte reaction, by the T cell mitogen phytohemagglutinin and by signal mimics of T cell activation (phorbol 12-myristate 13-acetate and calcium ionophore). Both trout IL-2 isoforms promoted PBL proliferation and sustained high-level expression of CD4 and CD8, suggesting that trout IL-2 isoforms are T cell growth/survival factors mainly expressed by activated T cells. The recombinant proteins for these two trout IL2 paralogs have been produced in E. coli and possess shared but also distinct bioactivities. IL-2A, but not IL-2B, induced IL12P35A1 and CXCR1 expression in PBL. IL-2B had a stronger effect on upregulation of the T helper 1 (Th1) cytokine interferon-γ (IFNγ) and could sustain CD8α and CD8β expression levels. Nevertheless, both cytokines upregulated key Th1 (IFNγ1, IFNγ2, TNFα2 and IL12) and T helper 2 (Th2) cytokines (IL4/13B1 and IL4/13B2), cytokine and chemokine receptors and the antimicrobial peptide cathelicidin-1 but had limited effects on T helper 17 cytokines and TGFβ1 in PBL. They could also enhance PBL phagocytosis. These results suggest, for the first time in fish, that IL-2 isoforms may have an important role in regulating Th1 and Th2 cell development, and innate and adaptive host defenses in fish, and shed light on lineage-specific expansion, evolution, and functional diversification of IL2 in vertebrates.

KW - salmonids

KW - interleukin-2

KW - expression

KW - bioactivity

KW - T cell growth factor

KW - T helper 1

KW - T helper 2

KW - phagocytosis

U2 - 10.3389/fimmu.2018.01683

DO - 10.3389/fimmu.2018.01683

M3 - Article

VL - 9

JO - Frontiers in Immunology

JF - Frontiers in Immunology

SN - 1664-3224

M1 - 1683

ER -