Identification of Treg-like cells in Tetraodon: insight into the origin of regulatory T subsets during early vertebrate evolution

Abstract

CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg cells) are critical for the maintenance of peripheral tolerance, and the suppression of autoimmune diseases and even tumors. Although Treg cells are well characterized in humans, little is known regarding their existence or occurrence in ancient vertebrates. In the present study, we report on the molecular and functional characterization of a Treg-like subset with the phenotype CD4-2(+)CD25-like(+)Foxp3-like(+) from a pufferfish (Tetraodon nigroviridis) model. Functional studies showed that depletion of this subset produced an enhanced mixed lymphocyte reaction (MLR) and nonspecific cytotoxic cell (NCC) activity in vitro, as well as inflammation of the intestine in vivo. The data presented here will not only enrich the knowledge of fish immunology but will also be beneficial for a better cross-species understanding of the evolutionary history of the Treg family and Treg-mediated regulatory networks in cellular immunity.

B Cells in Teleost Fish Act as Pivotal Initiating APCs in Priming Adaptive Immunity: An Evolutionary Perspective on the Origin of the B-1 Cell Subset and B7 Molecules

“…Recombinant proteins of zebrafish CD80/86, CD83, and CD4 were prepared as previously described (31)(32)(33)(34). Briefly, sequences encoding these proteins were amplified with primers (Supplemental Table I) containing corresponding restriction sites at the 59-and the 39-ends.…”

“…Cellular viability was determined by trypan blue (0.4%) exclusion assay. For membrane IgM (mIgm) + B and CD4 + T cell separation, immunomagnetic sorting (MACS) was performed, as previously described (33). Briefly, lymphocytes were adjusted to ∼2 3 10 8 cells/ml.…”

“…three times with rabbit anti-mIgM or nonspecific rabbit IgG (as control) at a dose of 10 mg/fish, followed by administration of Ags (10 mg KLH plus 10 ng LPS or 2 3 10 7 CFU V. alginolyticus), as previously described (33,39). In parallel, the PBS-treated group was set as a negative control.…”

IL-16 Induces Intestinal Inflammation via PepT1 Upregulation in a Pufferfish Model: New Insights into the Molecular Mechanism of Inflammatory Bowel Disease

“…Our previous studies have shown that TnIL-16 shares a number of similar characteristics with its mammalian counterpart in terms of gene organization, amino acid sequence, functional motifs or domains, molecular structure, protein cleavage site, and chemo- attractant function (29,75). Thus, IL-16 might be a highly conserved IL family member, which is conservative in both structure and function from fish to mammals throughout vertebrate evolution.…”

The gamma-chain cytokine/receptor system in fish: More ligands and receptors

“…Extensive analysis of fish genomes and the EST database has only identified IL-15Ra like molecules in fish [37,62]. Both the trout and tetraodon IL-15Ra like molecules contain a signal peptide, a single sushi domain, a Pro/Thr rich region, a transmembrane domain and have a short intracellular tail as seen in IL-15Ra from mammals, birds and amphibians [60,62].…”