Characterization of the turbot (Scophthalmus maximus) interleukin-18: Identification of splicing variants, phylogeny, synteny and expression analysis

• Main Authors: Pereiro, Patricia, Lama, R., Figueras Huerta, Antonio, Novoa, Beatriz
• Other Authors: Ministerio de Economía, Industria y Competitividad (España), Xunta de Galicia, Axencia Galega de Innovación
• Format: Still Image
• Language: English
• Published: 2022
• Subjects: Intlnterleukin-18; Teleost; Turbot; Splicing variants; Immune response; Norway; Scophthalmus maximus
• Online Access: http://hdl.handle.net/10261/285130; https://doi.org/10.13039/501100010769; https://doi.org/10.13039/501100010198; https://doi.org/10.13039/501100010801

Poster.-- 4th Congress of the International Society of Fish & Shellfish Immunology, December 12-15, 2022, Bode, Norway Interleukin-18 (IL-18) is a pro-inflammatory cytokine that belongs to the interleukin-1 (IL-1) family of cytokines. As occurs with IL-1 β. it is synthetized as an inactive precursor peptide that is mainly processed by the cysteine protease caspase-1 in the inflammasome complex. In mammals, and in collaboration with IL-12, it has been described as an important cytokine controlling the Thl-mediated immune responses through the induction of IFN-y. Although its function in mammals is well stablished, the activity of this cytokine in teleost remains to be elucidated. This could be due, among other things, to the absence of this gene in the fish model species zebrafish, but also to its complex regulation. As it was observed for rainbow trout and human, il18 splicing variants were also found in turbot, which could represent a regulatory mechanism of its bioactivity. In the case of turbot, three splicing variants were observed (SVl-3), and one of them showed an insertion of 10 amino acids in the middle of the potential caspase-1 cleavage position, reflecting that this is probably a form resistant to the processing by the inflammasome. Phylogenetic and threedimensional analyses of turbot iI18 revealed that it is relatively wellconserved in vertebrates, although only a partial conservation of the gene synteny was observed between fish and mammals. As it was expected, turbot il18 splicing variants were mainly expressed in immune tissues under healthy conditions, and their expression was induced by a bacterial challenge, although certain inhibitions were observed after viraland parasitic infections. In the case of the viral challenge, il18 downregulations did not seem to be due to the effect of type I IFNs This work was financially supported by the Ministerio de Economia, Industria y Competitividad of Spain (BIO2017-82851-0-2-R). Our laboratory is funded by the Interreg VA Spain-Portugal cooperation ...