Serazin, C. | Search bioRxiv

bioRxiv2021

CD4+ and CD8+ regulatory T cells characterization in the rat using a unique transgenic Foxp3-EGFP model.

BackgroundCD4+ and CD8+ regulatory T cells (Treg) in diverse species include different subsets from different origins. In all species, CD8+ Treg have been poorly characterized. CD4+ and CD8+ Treg in rats have only partially been characterized and there is no rat model in which FOXP3+ Treg are genetically tagged. ResultsWe generated a rat transgenic line using the CRISPR/Cas9 system in which EGFP was inserted in frame on the 3 end of the Foxp3 gene using a 2A self-cleaving peptide. EGFP was exclusively expressed by CD4+ and CD8+ T cells in similar proportion as observed with anti-FOXP3 antibodies. CD4+EGFP+ Treg were 5-10 times more frequent than CD8+EGFP+ Treg. CD4+ and CD8+ EGFP+ Treg expressed both the CD25highCD127lowCD45RClow/- markers. The suppressive activity of CD4+ and CD8+ Treg was largely confined to EGFP+ cells. RNAseq analyses showed similarities but also differences among CD4+ and CD8+ EGFP+ cells and provided the first description of the natural FOXP3+ CD8+ Treg transcriptome. In vitro culture of CD4+ and CD8+ EGFP- cells with TGFbeta and IL-2 resulted in the induction of EGFP+ Treg. Preferential expansion of CD4+ and CD8+ EGFP+ Treg could be detected upon in vivo administration of a low dose of IL-2. ConclusionsThis new and unique Foxp3-EGFP rat line constitutes a useful model to identify and isolate viable natural and induced CD4+ and CD8+ Treg. Additionally, it allows to identify new molecules expressed in CD8+ Treg that may allow to better define their phenotype and function not only in rats but also in other species.

immunology↗

bioRxiv2021

Generation of CD34+CD43+ hematopoietic progenitors to induce thymocytes from human pluripotent stem cells

Immunotherapy using primary T cells has revolutionized medical care in some pathologies in recent years but limitations associated to challenging cell genome edition, insufficient cell number production, the use of only autologous cells and lack of product standardization have limited its uses in the clinic. The alternative use of T cells generated in vitro from human pluripotent stem cells (hPSCs) offers great advantages by providing a self-renewing source of T cells that can be readily genetically modified and facilitate the use of standardized universal off-the-shelf allogeneic cell products and rapid clinic access. However, despite their potential, the feasibility and functionality of T-cells differentiated from hPSCs needs better comprehension before moving to the clinic. In this study, we generated human induced pluripotent stem cells from T-cells (T-iPSCs) allowing preservation of already recombined TCR, with the same properties as human embryonic stem cells (hESCs). Based on these cells, we differentiated with high efficiency hematopoietic progenitor stem cells (HPSCs), capable of self-renewal and differentiation into any cell blood type, and then DN3a thymic progenitors from several T-iPSC lines. To better comprehend differentiation, we analyzed the transcriptomic profiles of the different cell types and demonstrated that HPSCs differentiated from hiPSCs had a very similar profile to cord blood hematopoietic stem cells (HSCs). Furthermore, differentiated T-cell progenitors had a similar profile to thymocytes at the DN3a stage of thymic lymphopoiesis. Therefore, with this approach, we were able to regenerate precursors of therapeutic human T cells to potentially treat a wide number of diseases.

developmental biology↗