Elizabeth Phillips

Adverse drug reactions (ADR) are a significant concern in medicine due to their potential to cause substantial morbidity and mortality. Among the most serious of ADRs are severe cutaneous adverse reactions (SCARs), including Stevens-Johnson Syndrome (SJS)/toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis (AGEP), and generalized bullous fixed drug eruption (GBFDE). These conditions differ in phenotype, causative drugs, demographics, and latency (time between administration and reaction). We used the FDA Adverse Event Reporting System (FAERS), a comprehensive database with millions of reports submitted by providers, patients, and manufacturers, applying disproportionality measures and machine learning to analyze these rare reactions at scale. After sanitization and deduplication, FAERS was queried from 2004 to 2003 for SCAR cases. A total of 56,683 cases were reported, with median age 53 years (interquartile range [IQR] 32-68), with significant differences in age between phenotypes. Over 200 drugs had positive disproportionality signals. SCAR reporting has increased over time, particularly to biologics and checkpoint inhibitors. Using random forest classifiers, we showed causative drug is the most influential variable on latency, followed by number of concomitant drugs, and mortality is most strongly tied to age and number of concomitant drugs, regardless of SCAR phenotype. This largest retrospective study of SCAR to date shows the variety of phenotypes, causative agents, demographic variables, latencies, and mortality in SCAR patients. Continued mining of these databases, retrospective analyses of electronic health records, and prospective data can expand upon these results, better characterize variations, and improve recognition and care for patients with SCAR.

Background: Co-trimoxazole (Co-T), an antibiotic used globally for bacterial infections and opportunistic infection prophylaxis is one of the most common causes of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN); a life-threatening CD8+ T cell-dependent HLA-class I-restricted blistering drug eruption. We aimed to elucidate the differential single-cell immunopathology of Co-T SJS/TEN in persons living with HIV (PLWH) and without HIV (PLWoH).

Method: We obtained blister fluid cells (BC) from three populations: 1) Co-T SJS/TEN PLWH, all of whom were co-infected with tuberculosis (TB) (n = 5); PLWoH (n = 6), or 3) burns patients as control (n = 6). BC were analysed by 5’ scRNA-TCR-CITE-seq with bioinformatic normalization (CellRanger v9.0), transcriptome-based clustering (Seurat v5), and TCRαβ (ClusTCR), differential (VGAS), and proportional analyses (scCODA). Affected skin from two PLWoH with paired BC were analysed by 10x Visium-HD spatial transcriptomics.

Results: Private oligoclonal TCRαβ in blister fluid across Co-T SJS/TEN patients with shared HLA-class I peptide binding specificities were expressed by the same two populations of cytotoxic (GNLY, GZMB, PRF1) and proliferative (STMN1, TUBA1B, H2AFZ) CD8+ T-cells enriched in SJS/TEN and in contact with spatially resolved keratinocytes at the epidermal junction. At late timepoints pathogenic CD8+ T-cells were reduced while M1-like (STAT1, HLA) phagocytes transitioned to M2-like (RNASE1, LIPA) signatures indicative of wound repair. In Co-T SJS/TEN PLWH compared to PLWoH, CD8+ T-cells expressed markers of inactivation (EEF1A1, BTG1, ZFP36L2) and reduced expression of cytotoxic mediators (GNLY, GZMB). PLWH were further discerned by CD1C dendritic cells differentially enriched for markers of activation (CD83, CALR, AIF1), monocytes and macrophages for markers of immune regulation (THBS1, TFGBI, VCAN, STAB1), and CD4+ T-cells for markers of cytotoxicity (GNLY, GZMA), phosphodiesterase-signalling (PDE3B, PDE7B), and immune dysregulation (TFGB1, CRIP1).

Conclusion: We identify putative pathogenic TCR to model shared drug- and HLA-restriction and cell signatures that discern early (cytotoxic) from late (repair) disease processes and a unique cellular sub phenotype of SJS/TEN in PLWH associated with immune dysregulation. These data provide avenues toward personalised treatment approaches for patients with earlier- or later-stage disease and sub phenotypes of SJS/TEN associated with infectious co-morbidities.