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Modelling GATA2 immunodeficiency and the progression towards Myelodysplastic syndrome (MDS) and Acute myeloid leukaemia (AML)

Thomas, Leigh-Anne 2021. Modelling GATA2 immunodeficiency and the progression towards Myelodysplastic syndrome (MDS) and Acute myeloid leukaemia (AML). PhD Thesis, Cardiff University.
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Abstract

Heterozygous germline mutations in the GATA2 gene gives rise to an immunodeficiency syndrome characterised by cytopenias, severe infections and a predisposition towards haematological maligancies such as myeloidysplastic syndrome (MDS) and acute myeloid leukemia (AML). Clinical data from GATA2 mutated families reveal a variable age at presentation, a variable disease phenotype and a proportion of asymptomatic carriers, suggesting incomplete penetrance. Acquisition of secondary hits such as somatic mutations in the ASXL1 gene and cytogenetic abnormalities such as monosomy 7 and trisomy 8 are commonly found in patients that have progressed towards MDS/AML. Perturbation in the immune system of these patients leads to persistent inflammation. Indeed, scRNA-seq from patient samples showed immune and inflammatory pathway dysregulation at the HSC level, which has also been confirmed in our lab in HSCs from Gata2 heterozygous mice. Whilst there has been much research over the years investigating the loss of GATA2 in a variety of mouse and human models, many have failed to recapitulate key aspects of the disease. Using human iPSCs, primary cord blood CD34+ cells and transgenic mouse models, GATA2 immunodeficiency was modelled along with further investigations into inflammation as a potential driver of disease progression. In this thesis, CRISPR/Cas9 and CRISPR base editors were used to engineer specific GATA2 mutations - T354M and R361C – into human iPSC lines followed by truncating ASXL1 mutations to model GATA2 immunodeficiency and its progression towards myeloid malignancy. Unfortunately, due to technical and time limitations (including COVID19) this work was unable to be taken to fruition. Interestingly, in vitro bacterial stimulation selectively increased CFU output and CD14 expression in GATA2 knockdown cord blood CD34+ cells. In addition, chronic inflammation led to splenomegaly and granuloma formation along with a reduction of Gr1+ Mac1+ cells in the BM of mice with haematopoietic-specific deletion of a single Gata2 allele. Finally, in comparison with steady-state conditions where Gata2- heterozygous HSC levels were reduced by half, HSC numbers remained unchanged while control HSCs were reduced by half upon inflammation, indicating that Gata2 heterozygosity enabled HSCs mechanism to better adapt to inflammation. Taken together, this work highlights that a multi-model approach is desirable to study GATA2 familial MDS/AML and that inflammation is an important mediator for disease progression in GATA2 immunodeficiency syndromes thus opening new avenues for disease modelling and therapeutic intervention.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > Q Science (General)
Date of First Compliant Deposit: 29 April 2021
Last Modified: 25 Jun 2021 14:34
URI: http://orca.cardiff.ac.uk/id/eprint/140854

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