The first evidence of four transcripts from two Interleukin 18 genes in animal and their involvement in immune responses in the largest amphibian Andrias davidianus. (May 2020)

• Record Type: Journal Article
• Authors: Wang, Lan-Zhi; Xu, Ya-Ping; Zhou, Yi-Lian; Liu, Ze-Peng; Li, Bo; Gu, Wen-Bin; Zhao, Xiao-Feng; Dong, Wei-Ren; Shu, Miao-An
• Is Part Of: Developmental and comparative immunology. Volume 106(2020)
• Publication Date: 2020-05
• Subjects: IL-18 -- Andrias davidianus -- Amphibian -- Immune response; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2019.103598
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Interleukin 18 (IL-18), a member of IL-1 cytokine superfamily, is an important proinflammatory cytokine with multiple functions in both innate immunity and acquired immunity. However, the characteristics and functional roles of IL-18 remain largely unknown in amphibians, which were classed as major group of vertebrates. In the present study, two IL-18 genes ( AdIL-18A and AdIL-18B ) and four transcripts ( AdIL-18A1, AdIL-18A2, AdIL-18B1 and AdIL-18B2 ) were firstly identified and characterized from Chinese giant salamander ( Andrias davidianus ). To the best of our knowledge, this is the first report on the presence of more than one gene copy or two transcripts of IL-18 in one species. The complete open reading frames of Ad IL-18A1, Ad IL-18A2, Ad IL-18B1 and Ad IL-18B2 were 588 bp, 603 bp, 591 bp and 606 bp, respectively. The putative Ad IL-18 proteins possessed the typical IL-1 domains and phylogenetic analysis indicated that Ad IL-18s grouped together with other vertebrate IL-18 proteins. The expression profiles of AdIL-18 s were investigated under the challenges of Aeromonas hydrophila, Staphylococcus ureae and Poly (I:C) respectively, and the results suggested that Ad IL-18s were involved in the immune responses against both bacterial and viral infections. Moreover, the expression levels of two NF-κBs ( P100 and P105 ) and four proinflammatory cytokines ( IL-1β, IL-6, TNF-α and IFN-γ ) were inhibited in AdIL-18A1 / A2 -silenced cells when treated with bacteria and viral RNA analog. Additionally, the transcription levels of these immune-related cytokine genes were markedly induced when the lymphocytes were treated with recombinant Ad IL-18A1 or Ad IL-18A2 proteins, implying the involvement of Ad IL-18s in triggering NF-κB signaling and proinflammatory responses. These results might provide new insights into the origin or evolution of IL-18 in amphibians and even in vertebrates. Highlights: Four transcripts from two Interleukin 18 genes were firstly characterized in animals. Ad IL-18s responded to both bacterial and viral challenges. Ad IL-18s regulated the gene expressions of NF-κB signaling pathway and proinflammatory cytokines.