flow-cytometry-confocal-imaging-analysis-low-wnt-expression-axin2

Flow Cytometry and Confocal Imaging Analysis of Low Wnt Expression in Axin2-mTurquoise2 Reporter Thymocytes

Measuring Wnt expression levels is essential when trying to identify or test new Wnt therapeutic targets. Previous studies have shown that canonical Wnt ...

Leiden University Medical Center

Adequate responsiveness of CD8(+) T cell populations is of utmost importance for the efficacy of many vaccines and immunotherapeutic strategies against intracellular pathogens and cancer. In this study, we show in mouse models that the relative number of IL-2-producing cells within Ag-specific CD8(+) T cell populations predicts the population expansion capacity upon challenge. We further demonstrate that IL-2 producers constitute the best responding subset. Notably, we show that elevated production of IL-2 by CD8(+) T cells results in concomitant improved population expansion capacity and immunity. The amount of IL-2 produced on a per-cell basis essentially connects directly to the superior CD8(+) T cell population expansion. Together, our findings identified that autocrine IL-2 production operates in a dose-dependent fashion to facilitate the expansion potential of Ag-specific CD8(+) T cell populations, which may instigate ways to augment therapies depending on fit CD8(+) T cells. 

The Quantity of Autocrine IL-2 Governs the Expansion Potential of CD8+ T Cells.

The canonical Wnt signalling pathway has been implicated in organogenesis and self-renewal of essentially all stem cell systems. In vivo reporter systems are crucial to assess the role of Wnt signalling in the biology and pathology of stem cell systems. We set out to develop a Turquoise (TQ) fluorescent protein based Wnt reporter. We used a CRISPR-Cas9 approach to insert a TQ fluorescent protein encoding gene into the general Wnt target gene Axin2, thereby establishing a Wnt reporter mouse similar to previously generated Wnt reporter mice but with the mTurquoise2 gene instead of E. coli-β-galactosidase (LacZ). The use of mTurquoise2 is especially important in organ systems in which cells need to a be alive for further experimentation such as in vitro activation or transplantation studies. We here report successful generation of Axin2-TQ mice and show that cells from these mice faithfully respond to Wnt signals. High Wnt signals were detected in the intestinal crypts, a classical Wnt signalling site in vivo, and by flow cytometry in the thymus. These mice are an improved tool to further elucidate the role of Wnt signalling in vivo.

Axin2-mTurquoise2: A novel reporter mouse model for the detection of canonical Wnt signalling.

Hematopoietic stem cells maintain the homeostasis of all blood cell progeny during development and repopulation-demanding events. To study the lineage relationships during hematopoiesis, increasingly complex cell tracing models are being developed. In this study, we describe adaptations to the original  mouse model, which subsequently offers a relatively easy approach to study low complexity clonality during hematopoiesis, with special focus on B and T lymphocyte development. This protocol employs spatiotemporal Cre expression controlled by gammaretroviral transduction for efficient fluorescent protein cell marking. Transplantation of fluorescently marked Lin cKit hematopoietic progenitor cells into Rag1 mice, resulted in the visualization of differentially contributing stem cell clones to various lineages. Our methodology is useful to study questions in fundamental and preclinical hematopoietic research and  B- and T-cell development.

Development of an  model to study clonal lineage relationships in hematopoietic cells using  mice.

Recombinase-activating gene-1 (RAG1)-deficient severe combined immunodeficiency (SCID) patients lack B and T lymphocytes due to the inability to rearrange immunoglobulin and T cell receptor genes. Gene therapy is an alternative for those RAG1-SCID patients who lack a suitable bone marrow donor. We designed lentiviral vectors with different internal promoters driving codon-optimized  to ensure optimal expression. We used   mice as a preclinical model for RAG1-SCID to assess the efficacy of the various vectors. We observed that B and T cell reconstitution directly correlated with  expression. Mice with low  expression showed poor immune reconstitution; however, higher expression resulted in phenotypic and functional lymphocyte reconstitution comparable to mice receiving wild-type stem cells. No signs of genotoxicity were found. Additionally, RAG1-SCID patient CD34 cells transduced with our clinical RAG1 vector and transplanted into NSG mice led to improved human B and T cell development. Considering this efficacy outcome, together with favorable safety data, these results substantiate the need for a clinical trial for RAG1-SCID.

Article	Year
The Quantity of Autocrine IL-2 Governs the Expansion Potential of CD8+ T Cells. Journal of immunology (Baltimore, Md. : 1950)\| PubMed ID: 26453748	2015
Axin2-mTurquoise2: A novel reporter mouse model for the detection of canonical Wnt signalling. Genesis (New York, N.Y. : 2000)\| PubMed ID: 28875532	2017
Development of an model to study clonal lineage relationships in hematopoietic cells using mice. Future science OA\| PubMed ID: 31827896	2019
Successful Preclinical Development of Gene Therapy for Recombinase-Activating Gene-1-Deficient SCID. Molecular therapy. Methods & clinical development\| PubMed ID: 32322605	2020

Sandra A. Vloemans

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