Overexpression of T-bet, GATA-3 and TGF-ß Induces IFN-γ, IL-4/13A, and IL-17A Expression in Atlantic Salmon

Abstract

The overexpression of GATA-3, T-bet and TGF-ß may theoretically induce IL-4/A, IFN-γ and IL-17A expression, respectively. Whether this also applies to fish is not yet known. The plasmid vectors encoding reporter gene (RFP)-tagged T-bet, GATA-3 and TGF-ß were used as overexpression tools, transfected into cells or injected intramuscularly to monitor the expression of IFN-γ, IL-4/13A and IL-17A. In addition, the fish were either experimentally challenged with Vibrio anguillarum (VA group) or Piscirickettsia salmonis (PS group). The reporter gene (RFP) inserted upstream of the GATA-3, T-bet and TGF-ß genes, was observed in muscle cell nuclei and in inflammatory cells after intramuscular (i.m.) injection. PS group: following the injection of GATA-3 and T-bet-encoding plasmids, the expression of GATA-3 and T-bet was high at the injection site. The spleen expression of IFN-γ, following the injection of a T-bet-encoding plasmid, was significantly higher on day 2. VA group: The T-bet and GATA-3-overexpressing fish expressed high T-bet and GATA-3 mRNA levels in the muscles and on day 4 post-challenge. The expression of TGF-ß in the muscles of fish injected with TGF-ß-encoding plasmids was significantly higher on days 7 (8 days pre-challenge) and 19 (4 days after challenge). The protective effects of the overexpression of T-bet, GATA-3 and TGF-ß on both bacterial infections were negligible.

GATA-3 in Atlantic salmon (Salmo salar): Tissue distribution and its regulation of IL-4/13a promoter

“…IL-4, IL-5, IL-9, and IL-13 activate B cells and macrophages, which can either be protective or have adverse effects in immune response (Wynn, 2015). Our previous study showed that overexpression of GATA-3 in vivo upregulated IL-4/13a expression in salmon (Slettjord et al, 2020). In this study, we found that GATA-3 increased the promoter activity of IL-4/13a in vitro and the binding site was between -317 and -302 bp upstream of the transcriptional start site.…”

IL-2–mTORC1 signaling coordinates the STAT1/T-bet axis to ensure Th1 cell differentiation and anti-bacterial immune response in fish

“…It has been established that except for a few fish species (i.e., anglerfish and cod) that have lost the CD4/MHCII axis during evolution [24,25], most bony fish possess a CD4 + T-cell population. The fact that leukocytes or sorted CD4-1 + lymphocytes from several bony fish species express the IFN-γ, IL-4, and IL-17 genes and the transcription factors T-bet, GATA3, and RORγt, indicates that Th1-, Th2-and Th-17-like CD4 + T cells might exist in fish species [26][27][28][29][30][31][32]. However, despite these advances, the existence of CD3 + CD4 + IFN-γ + T cells, their detailed immunological functions, and differentiation mechanisms have not been well elucidated in bony fish.…”