A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Stevens - Johnson syndrome and Toxic Epidermal Necrolysis Syndrome are rare, but serious conditions affecting skin and mucous membranes that are primarily treated with supportive care. Other more specific therapies have limited evidence to support the benefit of their use; one such treatment is intravenous immunoglobulin (IVIG). The use of IVIG in the treatment of these syndromes remain controversial due to mixed results demonstrated in the literature, and at present is not considered a component of the standard of care. This study seeks to provide additional data regarding the efficacy of IVIG treatment on mortality in a small cohort of patients presenting with these syndromes at a regional burn center over a 10-year period; data was retrospectively collected from patient medical records. On analysis of this data, IVIG use showed a potential, but not significant. improvement on mortality in comparison to the non-treatment group. Compared with the non-treatment group, odds ratios for death were 0.81 (95% CI 0.3-2.0) for IVIG. There is ultimately no new evidence that the benefit of IVIG in the treatment of Stevens - Johnson syndrome and Toxic Epidermal Necrolysis Syndrome is anything more than potential. Further investigation should include a rigorous analysis and comparison of different dosing regimens.

Exfoliative loses of the skin are rare, but potentially lethal disorders that includes toxical epidermal necrolysis and staphylococcal scalded skin syndrome. They should be considered in a differential diagnosis and a quick transfer to the burn center is essential. The level of care and the effectiveness of the treatment at the burn unit significantly decreases the morbidity and mortality of these diseases. A transport of the patient proceeds with a time delay and the usage of the systemic corticosteroids at the previous hospital unit is frequent, according to the results of our clinical study. TEN patients are often unsuccesfully treated at the different units, mostly at the dermatological clinics and the infection diseases clinics, where the treatment of the involved skin surface is insufficient and corticosteroids are often administered. This evidence indicates that there is a requisiteness of an wider education intended for the medical public, especially for the medical members who may have a greater probability of encountering TEN patients.

La nécrolyse épidermique toxique (NET) est une réaction cutanée médicamenteuse (CADR - Cutaneous Adverse Drug Reaction) rare et sévère qui se caractérise par une nécrose brutale de l’épiderme, entraînant un décollement cutané plus ou moins étendu. Il s’agit d’une urgence vitale avec jusqu’à 30% de décès à la phase aiguë. L’importance de la surface décollée définit deux entités cliniques : le syndrome de Stevens-Johnson quand le décollement est inférieur à 10% et le syndrome de Lyell quand il est supérieur à 30%. A distance, le risque de complications, notamment sous forme de synéchies des muqueuses, est particulièrement élevé et doit être prévenu systématiquement. Le mécanisme physiopathologique repose essentiellement sur une réaction d’hypersensibilité médicamenteuse retardée dans laquelle les lymphocytes cytotoxiques jouent un rôle majeur. Le terrain génétique intervient également avec des associations HLA-médicament maintenant bien décrites, notamment dans les populations asiatiques. La question du traitement reste encore très débattue : il repose essentiellement sur la corticothérapie systémique, la ciclosporine ou encore les immunoglobulines IV. Quelques études suggèrent également un intérêt des anti-TNF-alpha. Le but de ce travail est de comprendre les mécanismes à l’origine des CADRs les plus sévères, à travers la caractérisation de patients atteints de NET à la phase aiguë et en les comparant à une CADR bénigne comme l’EMP. Nous avons dans un premier temps déterminé quelles étaient les principales populations CD45+ présentes à la phase aiguë des NET et de patients ayant présenté un exanthème maculo-papuleux (EMP) bénin, à la fois dans la peau et dans le sang. Nous avons cherché à déterminer la présence de populations cellulaires spécifiques de ces pathologies, notamment au sein des lymphocytes T CD8+ qui étaient la population majoritaire dans ces deux CADRs. Nous avons notamment montré qu’il existait une expansion majeure de lymphocytes T CD8+ effecteurs mémoires et polycytotoxiques au cours de la NET comparativement à l’EMP. Puis, nous nous sommes intéressés à la clonalité de ces populations lymphocytaires T CD8+ au travers de l’analyse de leurs séquences V-béta puis au moyen d’un séquençage ADN haut débit : nous avons notamment montré que ces expansions lymphocytaires T CD8+ étaient clonotypiques dans la peau. Nous avons également étudié l’expansion de ces clones cutanés dans le sang des patients atteints de NET et avons montré que leur expansion sanguine était directement corrélé à la sévérité clinique. Enfin, nous avons pu démontré in vitro chez deux patients que ces clones étaient spécifiques du médicament inducteur. / Toxic epidermal necrolysis (TEN) is a rare and severe cutaneous adverse drug reaction (CADR). The histologic hallmark of this reaction is necrosis with detachment of the epidermis resulting in skin blistering. This is a vital emergency with up to 30% deaths at the acute phase. The percentage of blistering skin determines two clinical entities: Stevens-Johnson syndrome when detachment represents less than 10% and Lyell's syndrome when it is greater than 30%. The development of late complications, notably mucous synechiae, is frequent and must be systematically prevented. Pathophysiologic mechanism consists in a delayed drug hypersensitivity reaction in which cytotoxic T lymphocytes play a major role. Genetic background is also very important with HLA-drug associations which have been reported, notably in asian ppopulations. Treatment remains very debated : systemic steroids, ciclosporin or intravenous immunoglobulins are commonly used. Some studies also suggest that TNF-alpha inhibitors are of interest in treating this disease. The aim of this work is to understand the mechanisms underlying the most severe CADRs, through the characterization of TEN patients. We first determined the main CD45+ populations present in the acute phase of both TEN and patients who devloped a benign maculo-papular exanthema (MPE). We sought to determine the presence of cell populations specific to these pathologies, particularly within CD8+ T lymphocytes, which were the majority population in these two CADRs. In particular, we have shown that there is a major expansion of CD8+ T lymphocytes in memory and polycytotoxic effectors during TEN compared to MPE. Then, we focused on the clonality of these CD8+ T lymphocyte populations through the analysis of their V-beta sequences and then by means of high throughput DNA sequencing: in particular, we showed that these CD8+ T lymphocyte expansions were clonotypic in the skin. We also studied the expansion of these skin clones in the blood of TEN patients and showed that their blood expansion was directly correlated with clinical severity. Finally, we were able to demonstrate in vitro in two patients that these clones were specific to the suspected drug

BACKGROUND: Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN) is the most severe form of cutaneous adverse drug reaction and is characterized by extensive epidermal destruction of the skin and mucosal surfaces. Controversy remains regarding the immunopathogenesis of the disease. It has long been assumed that CD8 cytotoxic T cells mediate cell death by releasing cytotoxic granules and soluble granulysin that trigger keratinocyte apoptosis. However, this does not explain the massive cell death or inflammation that is observed clinically. We have preliminary evidence from transcriptional profiling of patient skin samples suggesting that the cell death pathways necroptosis and pyroptosis may mediate SJS/TEN. Herein we utilize retrospectively and prospectively collected patient samples to investigate these cell death pathways. OBJECTIVE: The goals of this study are two-fold: (i) to investigate cell death pathways in retrospectively-collected (SJS/TEN) patient skin samples and (ii) to directly test the cell death mediators and pathways mediating SJS/TEN using a novel in vitro model. METHODS: Clinically and histopathologically confirmed SJS/TEN skin specimens and control skin specimens from non-blistering T cell mediated drug reactions and healthy skin were obtained following retrospective analysis from a multi-centered patient database. Gene expression profiling is being performed using the NanoString nCounter® System on these samples as a second patient cohort to confirm and expand on preliminary study findings. In parallel, we have optimized the use of a novel human skin platform for an in vitro model of SJS/TEN. We also collected human serum from a prospective study of SJS/TEN and control patients and have optimized and are actively collecting blister fluid from SJS/TEN and control patients in an ongoing prospective study for use in this model. RESULTS: Through an extensive pathology database and medical record search of potential cases at Brigham and Women's Hospital, we identified a second patient cohort of SJS/TEN, non-blistering delayed-type drug hypersensitivity reactions and healthy controls. We identified and are collecting thorough demographic, clinical and laboratory data on 61 potential candidates for SJS/TEN, 4 for Drug Reaction with Eosinophilia Syndrome (DRESS), and 200 for Morbilliform Drug Eruptions (MDE). This second cohort is in the final step of analysis with review by an expert clinician to confirm cases. In parallel, we have designed an expansive gene panel to confirm cell death mediator and marker transcription in our bank of skin samples. This 815 gene panel uses the pre-designed panel from Nanostring®, spiked with an additional 30 genes specific to apoptosis, pyroptosis, and necroptosis. We reviewed multiple potential in vitro skin models and identified GenoSkin® as the most suitable human skin platform for our in vitro model. We collected serum from 6 SJS/TEN patients and 6 non-blistering drug reaction patients and 3 healthy controls, and are actively collecting blister fluid from SJS/TEN and thermal burn control patients for analysis in this model. CONCLUSIONS: Our preliminary data suggest necroptosis and pyroptosis induced by soluble death mediators tumor necrosis factor (TNF) alpha and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as the main cell death pathways responsible for SJS/TEN. We have successfully identified a large number of potential patient samples of both cases and controls to perform transcriptional profiling using a self-designed gene panel to confirm and expand upon our preliminary data. We have successfully collected prospectively patient serum and are actively collecting patient blister fluid for analysis in an optimized in vitro model using GenoSkin®. SJS/TEN is severely understudied and lacks a standard protocol for care. This stems from uncertainty surrounding disease pathobiology. It is critical that we use innovative approaches to interrogate the mechanism mediating disease to advance the field, and, most importantly, to improve the quality of care for these patients.