Supplementary Thesis data.

This is the supplementary data for Mullan et al. Monash thesis (2018-2022). Abstract The unpredictable Type IV drug hypersensitivity reactions (DHRs) are T cell mediated reactions that range in severity from the mild maculopapular exanthema (MPE) to severe Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Unlike mild MPE reactions, SJS/TEN has associated morbidities and mortality in both acute and resolved disease. Anti-seizure medications (ASM), especially carbamazepine (CBZ), are among the most common causes of DHRs. The HLA-B*15:02 allele is strongly associated with increased risk of CBZ-SJS/TEN in East Asians but not in other populations (Odds ratio[OR]>2000), while another HLA allele, HLA-A*31:01, confers increased risk of CBZ-DHRs in European (OR: 25.9) and Japanese (OR: 33.9) populations. However, neither of these risk HLA allotypes are sufficient to cause CBZ-DHRs, which suggests other factors contribute to the DHR. To identify other risk factors, I used a multi-omics approach that involved two investigative modalities. The first was genomics, where I identified common variants from the whole genome of 116 ASM-SJS/TEN cases and 84 ASM tolerant controls. This analysis identified nine genome wide variants significantly associated with ASM-SJS/TEN. Using an interaction analysis to qualify the relative risk of the novel risk variant by HLA-B*15:02 carrier status, I identified two variants predicted to lower the relative risk of ASM-SJS/TEN, providing a potential explanation for ASM tolerance in some HLA-B*15:02 carriers. Additionally, the analysis suggested ASM-SJS/TEN had complex inheritance and indicated that many variants were contributing a small fraction of risk, and that some of these variants may not have reached genome wide significance (p-value HLA-A*31:01 or HLA-B*15:02 risk allele had a modest activation in the presence of CBZ and a keratinocyte cell line. This suggested direct CBZ presentation to the γδTCR through an unknown mechanism. Lastly, utilising the limited clinical DHR samples available, I confirmed CBZ can preferentially activate Vδ1+ T cells. Overall, ‘omics informed functional experimentation identified Vδ1+ T cells could have a role in the initiation and/or progression of CBZ-SJS/TEN, and follow-up utilising additional clinical samples is warranted. Additionally, I identified an opportunity to develop bespoke webtools for differential gene expression data (ggVolcanoR) and T cell receptor repertoire analysis (TCR_Explore). Overall this project utilised a multi-omics approach that identified novel biomarkers to aid in DHR classification, or as treatment targets. Importantly, the transcriptomics approach with T cell interrogations implicated a role for non-classical Vδ1+ T cells in CBZ-SJS/TEN pathogenesis.