Precision Medicine DTP - An Integrative Approach to Stratification in Alopecia Areata

Background

Alopecia areata (AA) is an autoimmune disease which causes hair loss. In addition to AA, individuals will often develop comorbid inflammatory conditions, including atopy. AA is driven by autoreactive NKG2D⁺CD8 T cells which recognise and attack hair follicles, leading to inhibition of the hair cycle growth and subsequent hair loss (1). Available treatments for AA lack efficacy, especially for severe disease where hair loss can affect the entire body. Fortunately, the involvement of T cells has led to wide scale testing of JAK-inhibitor therapy which has proven to be effective in early trials (2), with phase 3 trials for selective inhibition of JAK3 and JAK1/2 currently underway. These treatments are considered unlikely to become widely adopted, however, because the response is variable, disease relapse following treatment is common, and long term treatment may not be feasible due to increased susceptibility to infection. We hypothesise that disease heterogeneity, related to differences in the immune response in the early and established disease states, underlies underesponsiveness to targeted immune-therapies.

In our lab, we conducted comprehensive immunophenotyping of immune cells and cytokines in peripheral blood of people with AA. By comparing with controls, we observed increased proportions of CCR6⁺ ‘Th17’ CD4 T cells and associated type 17 cytokines, including IL-17A and IL-23 (3). In AA skin, CD4 T cells are abundant in follicular infiltrates and transcriptomic analysis indicates expansion of pathogenic CD4 T cell clones. Furthermore, transfer of CD4 T cells has been shown to mediate systemic hair loss in the AA mouse model. These data indicate that CD4 T cells are implicated in AA, yet their mechanistic involvement in pathology is not fully characterised.

This project will benefit from established relationships between:

• The Centre for Immunobiology at the University of Glasgow which has extensive experience in characterising immune responses and defining pathogenic mechanisms in patients with inflammatory disease.
• The AA Research Clinic based at the Queen Elizabeth University Hospital, run by Dr Susan Holmes.
• The Alopecia UK (AUK) charity who support the AA Clinic and associated biobank, and who are actively involved in the direction of our research.
• AstraZeneca who are committed to understanding inflammatory mechanisms underlying tissue specific immune pathology.

CD8 T cells are known to play a central role in the processes driving hair loss in AA. We have recently identified changes in CD4 T cell populations that also occur during the most immunologically active phase of disease, when hair follicles are under attack. In addition, our transcriptional analyses of skin samples that already lack hair have identified a strong transcriptional signature implicating IFN-gamma-producing cells in this ‘maintenance phase’ that occurs after hair has been lost. We therefore hypothesise that CD4 T cells, specifically IFN-gamma-producing subsets of CD4 T cells, play essential roles in driving and sustaining hair loss in AA.

We have three overlapping aims to address this hypothesis:

1. To characterise circulating IFN-gamma-producing cell populations and investigate how they impact CD8 T cell activity.
2. To perform molecular characterisation of CD4 T cell subsets in AA skin and assess their interactions with immune and non-immune cells. Using transcriptomic approaches, including single cell and spatial analyses, we will perform deep characterisation of IFN-gamma-producing cells in AA skin.
3. To test potential modulators of pathogenic immune cell function. With AstraZeneca, we will use specific molecular therapeutic tools to test whether targeted inhibition of pathways can modify pathogenic interactions in vitro. Candidate targets will be identified from the functional and transcriptome analyses in aims 2 and 3. 

Training outcomes

The student will gain a wide range of skills through this project. They will liaise with clinical staff to obtain anonymised tissue samples and linked data, and will gain familiarity with the ethical processes required for human research. They will perform wet lab techniques including flow cytometry and co-culture experiments with flow-sorted human cells. They will analyse gene and protein expression in tissues by IHC, and will perform specific experiments with the available GeoMX spatial profiler equipment. They will analyse these data, and also our single cell RNAseq dataset from human alopecia skin samples, to understand the pathogenesis of AA. The bioinformatic analyses will require them to become familiar with R. In this they will be supported by our in-house bioinformatician Mr Cole, and by 2^nd supervisor Dr Ijaz.

Application Instructions:

This MRC programme is joint between the Universities of Edinburgh and Glasgow. You will be registered at the host institution of the primary supervisor detailed in your project selection.

All applications should be made via the University of Edinburgh, irrespective of project location. For those applying to a University of Glasgow project, your application along with any supporting documents will be shared with University of Glasgow.

http://www.ed.ac.uk/studying/postgraduate/degrees/index.php?r=site/view&id=919

Please note, you must apply to one of the projects and you must contact the primary supervisor prior to making your application. Additional information on the application process is available from the link above.

For more information about Precision Medicine visit:

http://www.ed.ac.uk/usher/precision-medicine

Application Enquiries:

Susan Mitchell/Maree Hardie

[Email Address Removed] 

https://www.ed.ac.uk/usher/precision-medicine/app-process-eligibility-criteria