Single-cell characterisation of human Treg heterogeneity
The aim of this project is to leverage single-cell technologies to characterise the heterogeneity of human regulatory T cells (Tregs) in patients with autoimmune diseases. Recently we have developed in the lab a novel targeted single-cell RNA-sequencing (scRNA-seq) system to simultaneously quantify mRNA and protein expression at the single-cell level (https://genomemedicine.biomedcentral.com/articles/10.1186/s13073-020-00756-z). We will leverage these available resources to immunophenotype the human CD4+ Treg compartment, with an emphasis on the functionally heterogeneous HELIOS-FOXP3+ Treg subsets and their putative contribution to the pathogenesis of autoimmune diseases.
A major focus of this project will be to follow up on two subsets of FOXP3+ Tregs that we have previously characterised, namely a non-conventional CD25-FOXP3+ T-cell subset increased in patients with active autoimmunity (doi: 10.1016/j.jaut.2017.07.009), and an IL-6Rhi FOXP3+ Treg subset which is transiently increased in circulation upon treatment with IL-2 in vivo that has a distinct Th17 profile including the capacity to produce the prototypical pro-inflammatory cytokine IL-17 (doi: 10.1016/j.clim.2017.03.002). We will be investigating Tregs isolated from both blood and tissue to understand their functional diversity and to identify better markers that characterise these Treg subsets, which will allow us to monitor their frequency and response to Treg immunotherapy.
Furthermore, we are currently investigating peripheral Tregs in recently diagnosed T1D patients treated with ultra-low dose IL-2 from the DIL frequency trial (https://insight.jci.org/articles/view/99306). The aim of this study is to better understand the mechanism of exogenous IL-2 treatment in vivo and how it can be leveraged to treat autoimmune disease. Lessons from this project can also be extended to other clinical contexts such as treatment with expanded autologous Tregs, which is currently being trialled for the treatment of diverse autoimmune diseases and transplant patients.