Drug specific cytotoxic T-cells in the skin lesions of a patient with toxic epidermal necrolysis

Paraneoplastic dermatomyositis and Stevens-Johnson syndrome related to immunotherapy

Paraneoplastic syndromes such as dermatomyositis, often emerge as the initial clinical manifestation across various cancer types and are characterized by the development of B-cell responses targeting cancer-cell antigens that cross-react with normal skin and muscle cells. While these syndromes may alleviate following antineoplastic intervention, their response to immunotherapy remains elusive due to the exclusion of patients with autoimmune phenomena from clinical trials. In this report, we present the case of a female patient with advanced urothelial cancer presenting with dermatomyositis, who subsequently underwent treatment with anti-PD1 immunotherapy and experienced the onset of Stevens-Johnson syndrome. We discuss these two autoimmune entities and provide a comprehensive review of the existing literature to elucidate similar associations.

Tissue-Resident Memory T Cells in Allergy

Tissue-resident memory T (TRM) cells constitute a distinct subset within the memory T cell population, serving as the vanguard against invading pathogens and antigens in peripheral non-lymphoid tissues, including the respiratory tract, intestines, and skin. Notably, TRM cells adapt to the specific microenvironment of each tissue, predominantly maintaining a sessile state with distinctive phenotypic and functional attributes. Their role is to ensure continuous immunological surveillance and protection. Recent findings have highlighted the pivotal contribution of TRM cells to the modulation of adaptive immune responses in allergic disorders such as allergic rhinitis, asthma, and dermatitis. A comprehensive understanding of the involvement of TRM cells in allergic diseases bears profound implications for allergy prevention and treatment. This review comprehensively explores the phenotypic characteristics, developmental mechanisms, and functional roles of TRM cells, focusing on their intricate relationship with allergic diseases.

Glycolysis: An early marker for vancomycin-specific T-cell activation

BACKGROUND

Vancomycin, a glycopeptide antibiotic used for Gram-positive bacterial infections, has been linked with drug reaction with eosinophilia and systemic symptoms (DRESS) in HLA-A*32:01-expressing individuals. This is associated with activation of T lymphocytes, for which glycolysis has been isolated as a fuel pathway following antigenic stimulation. However, the metabolic processes that underpin drug-reactive T-cell activation are currently undefined and may shed light on the energetic conditions needed for the elicitation of drug hypersensitivity or tolerogenic pathways. Here, we sought to characterise the immunological and metabolic pathways involved in drug-specific T-cell activation within the context of DRESS pathogenesis using vancomycin as model compound and drug-reactive T-cell clones (TCCs) generated from healthy donors and vancomycin-hypersensitive patients.

METHODS

CD4+ and CD8+ vancomycin-responsive TCCs were generated by serial dilution. The Seahorse XFe96 Analyzer was used to measure the extracellular acidification rate (ECAR) as an indicator of glycolytic function. Additionally, T-cell proliferation and cytokine release (IFN-γ) assay were utilised to correlate the bioenergetic characteristics of T-cell activation with in vitro assays.

RESULTS

Model T-cell stimulants induced non-specific T-cell activation, characterised by immediate augmentation of ECAR and rate of ATP production (JATPglyc). There was a dose-dependent and drug-specific glycolytic shift when vancomycin-reactive TCCs were exposed to the drug. Vancomycin-reactive TCCs did not exhibit T-cell cross-reactivity with structurally similar compounds within proliferative and cytokine readouts. However, cross-reactivity was observed when analysing energetic responses; TCCs with prior specificity for vancomycin were also found to exhibit glycolytic switching after exposure to teicoplanin. Glycolytic activation of TCC was HLA restricted, as exposure to HLA blockade attenuated the glycolytic induction.

CONCLUSION

These studies describe the glycolytic shift of CD4+ and CD8+ T cells following vancomycin exposure. Since similar glycolytic switching is observed with teicoplanin, which did not activate T cells, it is possible the master switch for T-cell activation is located upstream of metabolic signalling.

TNF-α induced extracellular release of keratinocyte high-mobility group box 1 in Stevens-Johnson syndrome/toxic epidermal necrolysis: Biomarker and putative mechanism of pathogenesis

Decreased epidermal high-mobility group box 1 (HMGB1) expression is an early marker of epidermal injury in Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Etanercept, an anti-tumor necrosis factor therapeutic, is effective in the treatment of SJS/TEN. The objective was to characterize antitumor necrosis factor-alpha (TNF-α)-mediated HMGB1 keratinocyte/epidermal release and etanercept modulation. HMGB1 release from TNF-α treated (± etanercept), or doxycycline-inducible RIPK3 or Bak-expressing human keratinocyte cells (HaCaTs) was determined by western blot/ELISA. Healthy skin explants were treated with TNF-α or serum (1:10 dilution) from immune checkpoint inhibitor-tolerant, lichenoid dermatitis or SJS/TEN patients ± etanercept. Histological and immunohistochemical analysis of HMGB1 was undertaken. TNF-α induced HMGB1 release in vitro via both necroptosis and apoptosis. Exposure of skin explants to TNF-α or SJS/TEN serum resulted in significant epidermal toxicity/detachment with substantial HMGB1 release which was attenuated by etanercept. Whole-slide image analysis of biopsies demonstrated significantly lower epidermal HMGB1 in pre-blistered SJS/TEN versus control (P < 0.05). Keratinocyte HMGB1 release, predominantly caused by necroptosis, can be attenuated by etanercept. Although TNF-α is a key mediator of epidermal HMGB1 release, other cytokines/cytotoxic proteins also contribute. Skin explant models represent a potential model of SJS/TEN that could be utilized for further mechanistic studies and targeted therapy screening.

New insights into the diagnosis and management of Stevens-Johnson syndrome and toxic epidermal necrolysis

PURPOSE OF REVIEW

Recent studies have been clarifying the pathogenesis and early diagnostic markers of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Additionally, the efficacy of tumor necrosis factor alpha inhibitors is attracting attention. This review provides) recent evidence for the diagnosis and management of SJS/TEN.

RECENT FINDINGS

Risk factors for the development of SJS/TEN have been identified, particularly the association between HLA and the onset of SJS/TEN with specific drugs, which has been intensively studied. Research on the pathogenesis of keratinocyte cell death in SJS/TEN has also progressed, revealing the involvement of necroptosis, an inflammatory cell death, in addition to apoptosis. Diagnostic biomarkers associated with these studies have also been identified.

SUMMARY

The pathogenesis of SJS/TEN remains unclear and effective therapeutic agents have not yet been established. As the involvement of innate immunity, such as monocytes and neutrophils, in addition to T cells, has become clear, a more complex pathogenesis is predicted. Further elucidation of the pathogenesis of SJS/TEN is expected to lead to the development of new diagnostic and therapeutic agents.

High Serum Level of TNF-α in Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

BACKGROUND: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis are severe cutaneous adverse drug reactions. Some immunological and genetic factors are believed to be involved in the pathogenesis of SJS/TEN, including tumor necrotic factor-alpha (TNF-α). Activated T-cells secrete high amounts of TNF-α and interferon-gamma that both cytokines lead to increased expression and activity of keratinocyte inducible nitric oxide synthase playing an important role in the apoptosis of keratinocytes. AIM: This study aims to evaluate the serum level of TNF-α in SJS/TEN and the relation between it and the progress of SJS/TEN. METHODS: This was a sectional descriptive study conducted at the National Hospital of Dermatology and Venereology, in Hanoi, Vietnam, from October 2017 to September 2019. Forty-eight SJS/TEN patients, 43 erythema multiforme (EM) patients, and 20 healthy controls (HCs) participated. TNF-α levels were measured using the fluorescence covalent microbead immunosorbent assay (FCMIA) (ProcartaPlex Immunoassay Panels kit, Thermo Fisher Scientific, USA). The Mann–Whitney U-test was used to compare serum TNF-α levels of two groups. The Wilcoxon tests were used to compare quantitative variables before and after the treatment. Differences were considered to be statistically significant at p < 0.05. RESULTS: Nineteen SJS patients (39.5%) and 29 TEN patients (60.5%) participated in our study. The mean age was 49.3, range 19−77 years (47.9% of males and 52.1% of females). The most common causative drugs were traditional medicine (29.1%), carbamazepine (12.5%), and allopurinol (12.5%). On the day of hospitalization, the mean serum level of the SJS/TEN group was 32.6 pg/ml with a range from 1.3 pg/ml to 771.2 pg/ml. This level was significantly higher than that of the HCs group (p < 0.05) but not higher than that of the EM group. The mean serum level of TNF-α in the SJS/TEN patients on the day of hospitalization was 32.6 pg/ml, higher than that on the day of re-epithelialization (2.7 pg/ml) and the difference was statistically significant with p < 0.05. CONCLUSION: Serum TNF-α levels are a good biomarker to evaluate the progress of SJS/TEN but it is not good to differentiate SJS/TEN from EM.

Mixed T Helper1/T Helper2/T Cytotoxic Profile in Subjects with Chronic Chagas Disease with Hypersensitivity Reactions to Benznidazole

Dermatitis is the most common adverse event during treatment with benznidazole in chronic Chagas disease and is probably mediated by T cells. A set of molecules representative of the different type IV hypersensitivity reactions was evaluated in the circulation and skin biopsies of Trypanosoma cruzi-infected subjects presenting dermatitis during benznidazole administration. Through cytometric bead assays and enzyme-linked immunosorbent assay capture techniques, the serum levels of cytokines, chemokines, proapoptotic molecules, and mediators of the activation and migration of eosinophils and T cells were measured in subjects infected with Trypanosoma cruzi who exhibited skin adverse events (n = 22) and compared with those without adverse events (n = 37) during benznidazole therapy. Serum levels of interleukin- 5 (IL-5), soluble Fas cell surface death receptor ligand (FAS-L), and interferon γ-induced protein (IP-10) significantly increased at 7 to 30 days posttreatment with benznidazole and decreased thereafter in subjects with dermatitis but not in those without dermatitis. Circulating eotaxin levels were lower in subjects with dermatitis than in those without. Two patterns emerged in the skin biopsies: a T helper 1/T cytotoxic profile and a T helper 2/T cytotoxic profile with the presence of CD4⁺ and CD8⁺ T cells. Increased low-density lipoprotein (LDL), glutamic-oxaloacetic transaminase (GOT), uremia, and T cell activation emerged as risk factors for the development of dermatitis during benznidazole administration. These results support a delayed-type hypersensitivity reaction to benznidazole, involving CD4⁺ and CD8⁺ T cells and eosinophils, and a mixed cytokine profile. This study provides new insights for better management of adverse drug reactions to benznidazole. IMPORTANCE This study identified the risk factors for the development of adverse reactions to benznidazole and identified a set molecule to monitor the appearance of these reactions. This knowledge might improve the safety of benznidazole administration.

A Review of the Systemic Treatment of Stevens–Johnson Syndrome and Toxic Epidermal Necrolysis

Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are uncommon but life-threatening diseases mostly caused by drugs. Although various systemic immunomodulating agents have been used, their therapeutic efficacy has been inconsistent. This study aimed to provide an evidence-based review of systemic immunomodulating treatments for SJS/TEN. We reviewed 13 systematic review and meta-analysis articles published in the last 10 years. The use of systemic corticosteroids and IVIg is still controversial. An increasing number of studies have suggested the effectiveness of cyclosporine and biologic anti-TNF-α in recent years. There were also some promising results of combination treatments. Further large-scale randomized controlled trials are required to provide more definitive evidence of the effectiveness of these treatments. The pathogenesis of SJS/TEN has been elucidated in recent years and advances in the understanding of SJS/TEN may inspire the discovery of potential therapeutic targets.

IL-15/IL-15Rα in SJS/TEN: Relevant Expression of IL15 and IL15RA in Affected Skin

Stevens–Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a life-threatening hypersensitivity reaction to medications characterized by keratinocyte apoptosis and skin detachment. IL-15 serum levels have been associated with severity and prognosis of SJS/TEN. We have measured IL-15 concentrations in serum and blister fluid (BF) from patients with SJS/TEN by ELISA and used quantitative RT-PCR to analyze the expression of IL15 and IL15RA (encoding for IL-15 Receptor-α chain) genes in peripheral blood and BF cells, including isolated monocytes, and in affected skin. A positive correlation was found between IL-15 serum levels and a percent of detached skin. BF concentrations were higher, but no correlation was found. Higher IL15 and IL15RA gene expression levels were found in skin-infiltrating blister fluid cells compared to peripheral mononuclear cells. Moreover, IL15RA transcripts were barely detected in healthy skin, being the highest expression levels found in samples from two SJS/TEN patients who did not survive. The cutaneous expression of IL-15Rα in SJS/TEN may provide an explanation to the tissue-specific immune cytotoxic response in this clinical entity, and the results suggest that the effects of IL-15 in SJS/TEN patients may be dependent on the expression of its private receptor IL-15Rα in affected skin.

The Role of Patch Testing in Evaluating Delayed Hypersensitivity Reactions to Medications

Confirming drug imputability is an important step in the management of cutaneous adverse drug reactions (CADR). Re-challenge is inconvenient and in many cases life threatening. We review the literature on ideal patch testing technique for specific CADRs. Testing should be performed approximately 3 months after the resolution of the eruption using standard patch testing techniques. Commercially available patch test preparations are available for a minority of drugs, so in most cases, testing should be performed with the drug at various recommended concentrations and in different vehicles. Testing to all known excipients, such as dyes, vehicles and preservatives is also important. Immunosuppressive medications should be discontinued or down titrated to the lowest tolerable dose to decrease the risk of false negative reactions. We provide an overview of expert recommendations and extant evidence on the utility of patch testing for identifying the culprit drug in common CADRs and for specific drug or drug classes. Overall, there appears to be significant variability in the patch test positivity of different drugs, which is likely the result of factors intrinsic to the drug such as dermal absorption (as a function of lipophilicity and molecular size) and whether the drug itself or a downstream metabolite is implicated in the immune reaction. Drugs with high patch test positivity rates include beta-lactam antibiotics, aromatic anticonvulsants, phenytoin, and corticosteroids, among others. Patch testing positivity varies both as a function of the drug and type of CADR. The sum of the evidence suggests that patch testing in the setting of morbilliform eruptions, fixed drug eruption, acute generalized exanthematous pustulosis, and possibly also drug-induced hypersensitivity syndrome, photoallergic and eczematous reactions may be worthwhile, although utility of testing may vary on the specific drug in question for the eruption. It appears to be of limited utility and is not recommended in the setting of other complex CADR, such as SJS/TEN and leukocytoclastic vasculitis.

The important role of non-covalent drug-protein interactions in drug hypersensitivity reactions

Drug hypersensitivity reactions (DHR) are heterogeneous and unusual immune reactions with rather unique clinical presentations. Accumulating evidence indicates that certain non‐covalent drug‐protein interactions are able to elicit exclusively effector functions of antibody reactions or complete T‐cell reactions which contribute substantially to DHR. Here, we discuss three key interactions; (a) mimicry: whereby soluble, non‐covalent drug‐protein complexes (“fake antigens”) mimic covalent drug‐protein adducts; (b) increased antibody affinity: for example, in quinine‐type immune thrombocytopenia where the drug gets trapped between antibody and membrane‐bound glycoprotein; and (c) p‐i‐stimulation: where naïve and memory T cells are activated by direct binding of drugs to the human leukocyte antigen and/or T‐cell receptors. This transient drug‐immune receptor interaction initiates a polyclonal T‐cell response with mild‐to‐severe DHR symptoms. Notable complications arising from p‐i DHR can include viral reactivations, autoimmunity, and multiple drug hypersensitivity. In conclusion, DHR is characterized by abnormal immune stimulation driven by non‐covalent drug‐protein interactions. This contrasts DHR from “normal” immunity, which relies on antigen‐formation by covalent hapten‐protein adducts and predominantly results in asymptomatic immunity.

Systemic Corticosteroid Therapy for Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis in Vietnam: Clinical Evaluation and Analysis of Serum Cytokines

Abstract BACKGROUND: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis are severe cutaneous adverse drug reactions. There are some immunological and genetic factors which are believed to be involved in the pathogenesis of SJS/TEN. The treatment of SJS/TEN is still controversial in which several studies showed variable results. AIMS: To evaluate clinically the efficacy of systemic corticosteroid and to analyze some related cytokines in the treatment of SJS/TEN. METHODS: This open, pilot and uncontrolled study was conducted at National Hospital of Dermatology and Venereology, in Hanoi, Vietnam, from October 2017 to September 2019. Methylprednisolone was indicated from the first day of hospitalization with the dose of 0.5-2.5 mg/kg/day (calculated according to prednisolone dose) once daily. It was continued until the patients got re-epithelialization. The efficacy of methylprednisolone was evaluated by observing clinically and analyzing related cytokines before and after the treatment. RESULTS: The mean time of re-epithelialization was 15.9 days, of hospitalization was 15.9 days (range 5-30 days). There was no in-hospital mortality in this study. The most common complication was transient glycaemia (40.6%), there was no patient with sepsis. At the day of hospitalization, serum concentrations of TNF-α, IFN-γ, IL-2, IL-5, IL-13 and IL-10 were significantly higher than those at the day of re-epithelialization (p<0.05). Serum levels of IL-4, did not have significant differences between two time points (p>0.05). CONCLUSION: The systemic corticosteroid is a good choice in the treatment of SJS/TEN. It can reduce serum levels of some cytokines that help SJS/TEN patients with avoiding mortality.

A contemporary snippet on clinical presentation and management of toxic epidermal necrolysis

Introduction

Toxic epidermal necrolysis (TEN) is one of the most severe cutaneous adverse reactions with a mortality rate of 30%. Due to a lack of consensus regarding the treatment and management of TEN, therapy is individualized on a case-to-case basis.

Purpose

The scientific literature about Stevens-Johnson Syndrome (SJS) and TEN is summarized and assessed to aid and assist in determining the optimal course of treatment.

Methods

PubMed and Google Scholar, among others, were searched with the keywords: “Toxic Epidermal Necrolysis”, “corticosteroids”, “cyclosporine”, “etanercept”, “intravenous immunoglobulin”, “Stevens-Johnson syndrome” and filtered by year. The research articles generated by the search, and their references, were reviewed.

Results

TEN is a severe dermatological condition that is mainly caused by medicines. World-wide guidelines differ in care plans. As there is no consensus on the management of TEN, this article aims to summarize the efficacy and feasibility of the management aspect of TEN from previous studies. Supportive care is highly accepted, along with early discontinuation of all medicines (hydration & electrolytes). Corticosteroids and cyclosporine have been used in therapy. Intravenous immunoglobulin (IVIG) is currently being administered; however, their efficacy by themselves and in combination remains uncertain.

Conclusion

Current evidence predominantly from retrospective studies suggests no individual treatment has sufficient efficacy and a multi-faceted regimen stands to be favored. Therapeutic regimens from corticosteroids to IVIG are under constant evaluation. The life-threatening nature of TEN warrants further confirmation with more extensive, robust randomized, controlled trials.

Lay Summary

Toxic epidermal necrolysis (TEN) is a serious skin reaction with a 30% chance of mortality. Commonly TEN is caused by medicines and results in a burn like appearance and sensation in patients. Usually administered medicine is cleared effectively by the human body but when the clearance of few metabolites from medicine is disrupted due to few genes, it leads to an ominous response by the body. This response involves several intermediate chemicals that primarily attack skin cells. Treatment guidelines differ globally. Supportive care is highly accepted, along with early discontinuation of all medicine. Currently, a multi-faceted treatment regimen is favored. Treatments like corticosteroids to immunoglobulins are under constant evaluation. Identification of the perfect combination of treatment needs confirmation from robust randomized controlled trials.

Neutrophil Extracellular Traps in Skin Diseases

Neutrophils are the primary innate immune cells, and serve as sentinels for invading pathogens. To this end, neutrophils exert their effector functions via phagocytosis, degranulation, reactive oxygen species generation, and neutrophil extracellular trap (NET) release. Pathogens and pathogen-derived components trigger NET formation, leading to the clearance of pathogens. However, NET formation is also induced by non-related pathogen proteins, such as cytokines and immune complexes. In this regard, NET formation can be induced under both non-sterile and sterile conditions. NETs are enriched by components with potent cytotoxic and inflammatory properties, thereby occasionally damaging tissues and cells and dysregulating immune homeostasis. Research has uncovered the involvement of NETs in the pathogenesis of several connective tissue diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and ANCA-associated vasculitis. In dermatology, several skin diseases clinically develop local or systemic sterile pustules and abscesses. The involvement of neutrophils and subsequent NET formation has recently been elucidated in these skin diseases. Therefore, this review highlights the NETs in these neutrophil-associated diseases.

Pathological functions of granzyme B in inflammatory skin diseases

Dysregulated skin immunity is a hallmark of many skin diseases such as atopic dermatitis, autoimmune blistering diseases, and interface dermatitis. Current treatment options for the inflammatory skin diseases are limited and sometimes ineffective, therefore further understanding of pathomechanisms in the inflammatory skin conditions is necessary to develop new therapeutic alternatives. Recent studies suggest that the serine protease, granzyme B, is a key mediator in multiple inflammatory skin diseases, implying that strategies targeting granzyme B may be an attractive treatment option for such diseases. Specifically, granzyme B exhibits not only an intracellular apoptotic function but also extracellular proteolytic roles in inflammatory skin diseases including infectious diseases, pemphigoid diseases, atopic dermatitis, alopecia areata, and interface dermatitis. In this review, we summarize the current understanding with respect to the functions of granzyme B in the pathomechanism of various inflammatory skin diseases and evaluate the possibility of therapeutics targeting granzyme B.

Neutrophils initiate and exacerbate Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening mucocutaneous adverse drug reactions characterized by massive epidermal detachment. Cytotoxic T cells and associated effector molecules are known to drive SJS/TEN pathophysiology, but the contribution of innate immune responses is not well understood. We describe a mechanism by which neutrophils triggered inflammation during early phases of SJS/TEN. Skin-infiltrating CD8⁺ T cells produced lipocalin-2 in a drug-specific manner, which triggered the formation of neutrophil extracellular traps (NETs) in early lesional skin. Neutrophils undergoing NETosis released LL-37, an antimicrobial peptide, which induced formyl peptide receptor 1 (FPR1) expression by keratinocytes. FPR1 expression caused keratinocytes to be vulnerable to necroptosis that caused further release of LL-37 by necroptotic keratinocytes and induced FPR1 expression on surrounding keratinocytes, which likely amplified the necroptotic response. The NETs-necroptosis axis was not observed in less severe cutaneous adverse drug reactions, autoimmune diseases, or neutrophil-associated disorders, suggesting that this was a process specific to SJS/TEN. Initiation and progression of SJS/TEN keratinocyte necroptosis appear to involve a cascade of events mediated by innate and adaptive immune responses, and understanding these responses may contribute to the identification of diagnostic markers or therapeutic targets for these adverse drug reactions.

Genomic Risk Factors Driving Immune-Mediated Delayed Drug Hypersensitivity Reactions

Adverse drug reactions (ADRs) remain associated with significant mortality. Delayed hypersensitivity reactions (DHRs) that occur greater than 6 h following drug administration are T-cell mediated with many severe DHRs now associated with human leukocyte antigen (HLA) risk alleles, opening pathways for clinical prediction and prevention. However, incomplete negative predictive value (NPV), low positive predictive value (PPV), and a large number needed to test (NNT) to prevent one case have practically prevented large-scale and cost-effective screening implementation. Additional factors outside of HLA contributing to risk of severe T-cell-mediated DHRs include variation in drug metabolism, T-cell receptor (TCR) specificity, and, most recently, HLA-presented immunopeptidome-processing efficiencies via endoplasmic reticulum aminopeptidase (ERAP). Active research continues toward identification of other highly polymorphic factors likely to impose risk. These include those previously associated with T-cell-mediated HLA-associated infectious or auto-immune disease such as Killer cell immunoglobulin-like receptors (KIR), epistatically linked with HLA class I to regulate NK- and T-cell-mediated cytotoxic degranulation, and co-inhibitory signaling pathways for which therapeutic blockade in cancer immunotherapy is now associated with an increased incidence of DHRs. As such, the field now recognizes that susceptibility is not simply a static product of genetics but that individuals may experience dynamic risk, skewed toward immune activation through therapeutic interventions and epigenetic modifications driven by ecological exposures. This review provides an updated overview of current and proposed genetic factors thought to predispose risk for severe T-cell-mediated DHRs.

Massive clonal expansion of polycytotoxic skin and blood CD8+ T cells in patients with toxic epidermal necrolysis

Toxic epidermal necrolysis (TEN) is a life-threatening cutaneous adverse drug reaction. To better understand why skin symptoms are so severe, we conducted a prospective immunophenotyping study on skin and blood. Mass cytometry results confirmed that effector memory polycytotoxic CD8⁺ T cells (CTLs) are the main leucocytes in TEN blisters at the acute phase. Deep T cell receptor (TCR) repertoire sequencing identified massive expansion of unique CDR3 clonotypes in blister cells. The same clones were highly expanded in patient's blood, and the degree of their expansion showed significant correlation with disease severity. By transducing α and β chains of the expanded clonotypes into a TCR-defective cell line, we confirmed that those cells were drug specific. Collectively, these results suggest that the relative clonal expansion and phenotype of skin-recruited CTLs condition the clinical presentation of cutaneous adverse drug reactions.

The Role of IL-13, IL-15 and Granulysin in the Pathogenesis of Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis (TEN) are Severe Cutaneous Adverse Reactions (SCARS) characterized by fever and mucocutaneous lesions leading to necrosis and sloughing of the epidermis. Conjunctival lesions are reported in 85% of patients. The pathogenesis of SJS/TEN/SCARS is not completely understood. It is hypothesized that IL-13, IL-15 and Granulysin expressed in plasma and skin may play a role. We measured the circulating levels of these cytokines in the plasma using ELISA and their expression in the skin using immunofluorescence microscopy. A total of 12 SJS/TEN skin biopsy samples (8 SJS, 2 SJS/TEN overlap and 2 TEN) were analyzed. Biopsy samples from patients with Lichen Planus (an inflammatory condition of the skin and mucous membranes) served as controls. Studies were also performed in human corneal epithelial cells where expression of these cytokines were measured following a challenge with TNF-α (0, 1, 10 and 100 ng/ml). The intensity of immunofluorescence was measured Using Imaris® software. The results showed significantly increased expression of these cytokines in the skin biopsy samples as measured by the average intensities of IL-13 (6.1 x 133.0 ± 4.231 x 10^8), and Granulysin (4.2 x 123.0 ± 4.231 x 10^8) compared to Lichen planus control (3.0 x 123.0 ±1.62 x 10^5). Increased expression of IL-13 and IL-15 were noted in cell culture studies and in the plasma samples when compared to Normal Human Plasma as controls. It is concluded that IL-13, IL-15 and Granulysin play a role in the pathogenesis of SJS/TEN.

Predictive biomarkers for the progression of ocular complications in chronic Stevens-Johnson syndrome and toxic Eeidermal necrolysis

This study aimed to clarify predictive biomarkers of mild and severe ocular complications of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) by examining the cytokines in tears. In 121 chronic-phase SJS/TEN eyes, cytokines in tear samples collected using Schirmer test strips were measured, and ocular sequelae severity was evaluated using an Ocular Surface Grading Score (OSGS) involving 7 components (conjunctivalization, neovascularization, opacification, keratinization, symblepharon, and upper/lower conjunctival-sac shortening), with findings categorized into grades 0–3 (maximum total OSGS: 21). Changes in cytokines between the mild and severe groups (mild: total OSGS of 10 or less, severe: total OSGS of 11 or more), and changes between SJS/TEN cases with and without each of the 7 components, were compared. In the severe group, there was significant upregulation of interleukin (IL)-8 (P < 0.01) and Granzyme B (GrzB) (P < 0.05). IL-8 was significantly upregulated in eyes with conjunctivalization, neovascularization, or opacification, GrzB was upregulated in eyes with keratinization, interferon-γ-inducible protein 10 (IP-10) was downregulated in eyes with conjunctivalization or neovascularization, and IL-1α was upregulated in eyes with opacification (all: P < 0.05). IL-8 and IP-10 was involved in conjunctivalization and neovascularization, while GrzB was involved in keratinization. IL-8 and GrzB in tears may reflect SJS/TEN-related ocular sequelae severity.

Clinical and pathogenic aspects of the severe cutaneous adverse reaction epidermal necrolysis (EN)

The severe cutaneous adverse reaction epidermal necrolysis (EN) which includes toxic epidermal necrolysis and the milder Stevens-Johnson syndrome is characterized by epidermal loss due to massive keratinocyte apoptosis and/or necroptosis. EN is often caused by a drug mediating a specific TCR-HLA interaction via the (pro)hapten, pharmacological interaction or altered peptide loading mechanism involving a self-peptide presented by keratinocytes. (Memory) CD8 + T cells are activated and exhibit cytotoxicity against keratinocytes via the perforin/granzyme B and granulysin pathway and Fas/FasL interaction. Alternatively drug-induced annexin release by CD14 + monocytes can induce formyl peptide receptor 1 death of keratinocytes by necroptosis. Subsequent keratinocyte death stimulates local inflammation, activating other immune cells producing pro-inflammatory molecules and downregulating regulatory T cells. Widespread epidermal necrolysis and inflammation can induce life-threatening systemic effects, leading to high mortality rates. Research into genetic susceptibility aims to identify risk factors for eventual prevention of EN. Specific HLA class I alleles show the strongest association with EN, but risk variants have also been identified in genes involved in drug metabolism, cellular drug uptake, peptide presentation and function of CD8 + T cells and other immune cells involved in cytotoxic responses. After the acute phase of EN, long-term symptoms can remain or arise mainly affecting the skin and eyes. Mucosal sequelae are characterized by occlusions and strictures due to adherence of denuded surfaces and fibrosis following mucosal inflammation. In addition, systemic pathology can cause acute and chronic hepatic and renal symptoms. EN has a large psychological impact and strongly affects health-related quality of life among EN survivors.

Recent advances in managing and understanding Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening diseases characterized by detachment of the epidermis and mucous membrane. SJS/TEN are considered to be on the same spectrum of diseases with different severities. They are classified by the percentage of skin detachment area. SJS/TEN can also cause several complications in the liver, kidneys, and respiratory tract. The pathogenesis of SJS/TEN is still unclear. Although it is difficult to diagnose early stage SJS/TEN, biomarkers for diagnosis or severity prediction have not been well established. Furthermore, optimal therapeutic options for SJS/TEN are still controversial.

Several drugs, such as carbamazepine and allopurinol, are reported to have a strong relationship with a specific human leukocyte antigen (HLA) type. This relationship differs between different ethnicities. Recently, the usefulness of HLA screening before administering specific drugs to decrease the incidence of SJS/TEN has been investigated.

Skin detachment in SJS/TEN skin lesions is caused by extensive epidermal cell death, which has been considered to be apoptosis via the Fas-FasL pathway or perforin/granzyme pathway. We reported that necroptosis, i.e. programmed necrosis, also contributes to epidermal cell death. Annexin A1, released from monocytes, and its interaction with the formyl peptide receptor 1 induce necroptosis. Several diagnostic or prognostic biomarkers for SJS/TEN have been reported, such as CCL-27, IL-15, galectin-7, and RIP3.

Supportive care is recommended for the treatment of SJS/TEN. However, optimal therapeutic options such as systemic corticosteroids, intravenous immunoglobulin, cyclosporine, and TNF-α antagonists are still controversial. Recently, the beneficial effects of cyclosporine and TNF-α antagonists have been explored. In this review, we discuss recent advances in the pathophysiology and management of SJS/TEN.

Mechanisms of Severe Cutaneous Adverse Reactions: Recent Advances

Cutaneous adverse drug reactions are unpredictable and include various different skin conditions of varying degrees of severity. The most concerning are usually referred to as severe cutaneous adverse reactions (SCARs) and include acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS), also known as drug-induced hypersensitivity syndrome (DiHS) or hypersensitivity syndrome (HSS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). All are delayed type IV hypersensitivity reactions in which a T-cell-mediated drug-specific immune response is responsible for causing the disease. Nonetheless, specific T-cell subpopulations develop in response to certain environmental conditions and produce cytokines that orchestrate the various phenotypes. Cytotoxic T lymphocytes (CTLs), T-helper type 1 (Th1), Th2, Th17, and regulatory T cells (Treg), among other T-cell subpopulations, participate in the development of SCAR phenotypes. Cell subpopulations belonging to the innate immune system, comprising natural killer cells, innate lymphoid cells, monocytes, macrophages and dendritic cells, can also participate in shaping specific immune responses in various clinical conditions. Additionally, tissue-resident cells, including keratinocytes, can contribute to epidermal damage by secreting chemokines that attract pro-inflammatory immunocytes. The final phenotypes in each clinical entity result from the complex interactions between a variety of cell lineages, their products, soluble mediators and genetic and environmental factors. Although the pathophysiology of these reactions is not fully understood, intensive research in recent years has led to major progress in our understanding of the contribution of certain cell types and soluble mediators to the variability of SCAR phenotypes.

TNFα inhibitor may be effective for severe COVID-19: learning from toxic epidermal necrolysis

Increased inflammatory cytokines [such as tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6)] are observed in COVID-19 patients, especially in the severe group. The phenomenon of a cytokine storm may be the central inducer of apoptosis of alveolar epithelial cells, which leads to rapid progression in severe group patients. Given the similarities of clinical features and pathogenesis between toxic epidermal necrolysis (TEN) and COVID-19, we hypothesize that the application of etanercept, an inhibitor of TNFα, could attenuate disease progression in severe group COVID-19 patients by suppressing systemic auto-inflammatory responses. The reviews of this paper are available via the supplemental material section.

HLA-associated antiepileptic drug-induced cutaneous adverse reactions

Adverse drug reactions (ADRs) are a common cause of hospital admissions (up to 19%), with the majority of cases due to off-target predictable drug effects (type A reactions). However, idiosyncratic drug-induced immune activated (type B) reactions contribute to a range of hypersensitivity reactions, with T-cell-mediated type IV hypersensitivity reactions mainly manifesting as cutaneous ADRs (cADRs). Aromatic antiepileptic drugs (AEDs), used in the treatment of epilepsy as well as bipolar disorder or neuropathic pain, have been implicated as culprit drugs in a spectrum of pathologies ranging from mild maculopapular exanthema (MPE) to severe and life-threatening conditions including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). These AED-induced cADRs are unpredictable based on pharmacological and clinical factors alone, thereby prompting investigations into genomic contributors mediating risk of pathology. The most strongly associated risk genes identified are from the human leukocyte antigen (HLA) class I alleles, which play a critical role in adaptive immunity by flagging either infected or aberrant cells for recognition by surveying T-cells. In the setting of drug hypersensitivity, the immunogenicity of HLA molecules and their peptide cargo can be modulated by interactions with small drug molecules that drive inappropriate T-cell responses. This review discusses the current understanding of HLA class I molecules in modifying risk of AED-induced cADRs.

Drug-Induced Skin Adverse Reactions: The Role of Pharmacogenomics in Their Prevention

Adverse drug reactions (ADRs) affect many patients and remain a major public health problem, as they are a common cause of morbidity and mortality. It is estimated that ADRs are responsible for about 6% of hospital admissions and about 9% of hospitalization costs. Skin is the organ that is most frequently involved in ADRs. Drug-induced skin injuries vary from mild maculopapular eruptions (MPE) to severe cutaneous adverse reactions (SCARs) that are potentially life threatening. Genetic factors have been suggested to contribute to these SCARs, and most significant genetic associations have been identified in the major histocompatibility complex (MHC) genes. Common drugs associated with SCARs connected with strong genetic risk factors include antiepileptic drugs (AEDs), allopurinol, abacavir, nevirapine, sulfonamides, dapsone, non-steroidal anti-inflammatory drugs (NSAIDs), and analgesic drugs. However, genetic associations vary between different ethnic populations. Differences may in part be explained by the different prevalence of HLA (human leukocyte antigen) alleles among ethnic groups. In this review, we present and discuss the recent advances in genetic associations with ADRs in the skin. Many of these ADRs are now preventable with pharmacogenetic screening.

Carbamazepine-Mediated Adverse Drug Reactions: CBZ-10,11-epoxide but Not Carbamazepine Induces the Alteration of Peptides Presented by HLA-B∗15:02

Among patients treated with the anticonvulsive and psychotropic drug carbamazepine (CBZ), approximately 10% develop severe and life-threatening adverse drug reactions. These immunological conditions are resolved upon withdrawal of the medicament, suggesting that the drug does not manifest in the body in long term. The HLA allele B∗15:02 has been described to be a genomic biomarker for CBZ-mediated immune reactions. It is not well understood if the immune reactions are triggered by the original drug or by its metabolite carbamazepine-10,11-epoxide (EPX) and how the interaction between the drug and the distinct HLA molecule occurs. Genetically engineered human B-lymphoblastoid cells expressing soluble HLA-B∗15:02 molecules were treated with the drug or its metabolite. Functional pHLA complexes were purified; peptides were eluted and sequenced. Applying mass spectrometric analysis, CBZ and EPX were monitored by analyzing the heavy chain and peptide fractions separately for the presence of the drug. This method enabled the detection of the drug in a biological situation post-pHLA assembly. Both drugs were bound to the HLA-B∗15:02 heavy chain; however, solely EPX altered the peptide-binding motif of B∗15:02-restricted peptides. This observation could be explained through structural insight; EPX binds to the peptide-binding region and alters the biochemical features of the F pocket and thus the peptide motif. Understanding the nature of immunogenic interactions between CBZ and EPX with the HLA immune complex will guide towards effective and safe medications.

Current Perspectives on Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are considered a delayed-type hypersensitivity reaction to drugs. They represent true medical emergencies and an early recognition and appropriate management is decisive for the survival. SJS/TEN manifest with an "influenza-like" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms. The difference between SJS, SJS/TEN overlap, and TEN is defined by the degree of skin detachment: SJS is defined as skin involvement of < 10%, TEN is defined as skin involvement of > 30%, and SJS/TEN overlap as 10-30% skin involvement. The diagnosis of different degrees of epidermal necrolysis is based on the clinical assessment in conjunction with the corresponding histopathology. The mortality rates for SJS and TEN have decreased in the last decades. Today, the severity-of-illness score for toxic epidermal necrolysis (SCORTEN) is available for SJS/TEN severity assessment. Drugs with a high risk of causing SJS/TEN are anti-infective sulfonamides, anti-epileptic drugs, non-steroidal anti-inflammatory drugs of the oxicam type, allopurinol, nevirapine, and chlormezanone. Besides conventional drugs, herbal remedies and new biologicals should be considered as causative agents. The increased risk of hypersensitivity reactions to certain drugs may be linked to specific HLA antigens. Our understanding of the pathogenesis of SJS/TEN has improved: drug-specific T cell-mediated cytotoxicity, genetic linkage with HLA- and non-HLA-genes, TCR restriction, and cytotoxicity mechanisms were clarified. However, many factors contributing to epidermal necrolysis still have to be identified, especially in virus-induced and autoimmune forms of epidermal necrolysis not related to drugs. In SJS/TEN, the most common complications are ocular, cutaneous, or renal. Nasopharyngeal, esophageal, and genital mucosal involvement with blisters, erosions as well as secondary development of strictures also play a role. However, in the acute phase, septicemia is a leading cause of morbidity and fatality. Pulmonary and hepatic involvement is frequent. The acute management of SJS/TEN requires a multidisciplinary approach. Immediate withdrawal of potentially causative drugs is mandatory. Prompt referral to an appropriate medical center for specific supportive treatment is of utmost importance. The most frequently used treatments for SJS/TEN are systemic corticosteroids, immunoglobulins, and cyclosporine A.

Diverse expression of TNF-α and CCL27 in serum and blister of Stevens-Johnson syndrome/toxic epidermal necrolysis

Background

The pathogenesis of Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) is not fully understood. Our previous study reported that chemokine CCL27 was overexpressed in serum of SJS/TEN patients. The objective of this study was to investigate the levels of CCL27 and TNF-α in serum and blister fluid from patients with SJS/TEN during the acute stage or resolution phase.

Methods

A total of 27 patients with SJS/TEN and 39 healthy donors were recruited to the study. Serum and vesicular levels of CCL27 and TNF-α were determined by enzyme-linked immunosorbent assays.

Results

Serum levels of CCL27 and TNF-α were significantly elevated in patients with SJS/TEN during the acute stage as compared to the resolution phase and also compared with levels observed in normal controls (P = 0.001/< 0.001; P = 0.012/< 0.001). Serum TNF-α levels were significantly higher in patients with SJS/TEN during the resolution phase compared with normal controls (P < 0.001). Serum CCL27 levels were positively correlated with TNF-α levels during the acute stage (r_s = 0.660; P < 0.001). Blister fluid exhibited much lower CCL27 levels than serum did during the acute stage (P = 0.008). TNF-α levels were much higher in vesicles in contrast to serum from acute stage (P = 0.040) as well as serum from resolution phase (P = 0.029).

Conclusions

Our study demonstrated roles of CCL27 and TNF-α in promoting the course of SJS/TEN. CCL27 may act early in the course of disease, via the circulation, whereas TNF-α acts throughout the course of disease, in skin lesions.

Drug-Induced Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis Call for Optimum Patient Stratification and Theranostics via Pharmacogenomics

The Global Genomic Medicine Collaborative, a multinational coalition of genomic and policy experts working to implement genomics in clinical care, considers pharmacogenomics to be among the first areas in genomic medicine that can provide guidance in routine clinical practice, by linking genetic variation and drug response. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe life-threatening reactions to medications with a high incidence worldwide. Genomic screening prior to drug administration is a key opportunity and potential paradigm for using genomic medicine to reduce morbidity and mortality and ultimately eliminate one of the most devastating adverse drug reactions. This review focuses on the current understanding of the surveillance, pathogenesis, and treatment of SJS/TEN, including the role of genomics and pharmacogenomics in the etiology, treatment, and eradication of preventable causes of drug-induced SJS/TEN. Gaps, unmet needs, and priorities for future research have been identified for the optimal management of drug-induced SJS/TEN in various ethnic populations. Pharmacogenomics holds great promise for optimal patient stratification and theranostics, yet its clinical implementation needs to be cost-effective and sustainable.

An Updated Review of the Molecular Mechanisms in Drug Hypersensitivity

Drug hypersensitivity may manifest ranging from milder skin reactions (e.g., maculopapular exanthema and urticaria) to severe systemic reactions, such as anaphylaxis, drug reactions with eosinophilia and systemic symptoms (DRESS)/drug-induced hypersensitivity syndrome (DIHS), or Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN). Current pharmacogenomic studies have made important strides in the prevention of some drug hypersensitivity through the identification of relevant genetic variants, particularly for genes encoding drug-metabolizing enzymes and human leukocyte antigens (HLAs). The associations identified by these studies are usually drug, phenotype, and ethnic specific. The drug presentation models that explain how small drug antigens might interact with HLA and T cell receptor (TCR) molecules in drug hypersensitivity include the hapten theory, the p-i concept, the altered peptide repertoire model, and the altered TCR repertoire model. The broad spectrum of clinical manifestations of drug hypersensitivity involving different drugs, as well as the various pathomechanisms involved, makes the diagnosis and management of it more challenging. This review highlights recent advances in our understanding of the predisposing factors, immune mechanisms, pathogenesis, diagnostic tools, and therapeutic approaches for drug hypersensitivity.

Clinical Pharmacogenetics Implementation Consortium Guideline for HLA Genotype and Use of Carbamazepine and Oxcarbazepine: 2017 Update

The variant allele HLA-B*15:02 is strongly associated with greater risk of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in patients treated with carbamazepine or oxcarbazepine. The variant allele HLA-A*31:01 is associated with greater risk of maculopapular exanthema, drug reaction with eosinophilia and systemic symptoms, and SJS/TEN in patients treated with carbamazepine. We summarize evidence from the published literature supporting these associations and provide recommendations for carbamazepine and oxcarbazepine use based on HLA genotypes.

Predominance of CD14+ Cells in Burn Blister Fluids

BACKGROUND

Burn blister fluid contains several angiogenic factors to promote wound neovascularization. In our previous study, we found that deep partial-thickness burn (DPTB) wounds showed higher expression levels of angiogenin to enhance vascularization compared with superficial partial-thickness burn wounds. Neovascularization is a complex process that involves an interaction between circulating angiogenic cells and mediators. We hypothesized that in addition to angiogenic factors burn blisters may contain specific cell types. The aim of the present study was to characterize the specific cells present in burn blisters.

METHODS

Twenty-four burn blister fluid samples were obtained with informed consent from patients with superficial partial-thickness burn (n = 16) or DPTB (n = 8) wounds. Blister cells were isolated from individual intact blisters and characterized with flow cytometry analysis using CD14, CD34, vascular endothelial growth factor receptor 2, and CD133 markers. CD14 and CD34 blister cells were also isolated using a magnetic-activated cell sorting system to examine their potential for endothelial differentiation. Angiogenin levels in the burn blister fluids were evaluated with enzyme-linked immunosorbent assay.

RESULTS

CD14 cells were the most highly represented cell type in the burn fluids of both groups, although a significantly greater percentage of CD14 cells were observed in DPTB fluids. CD14 blister cells had a higher potency to differentiate into functional endothelial cells as compared with CD34 cells. The proportion of CD14 cells gradually increased after burn injury. In contrast to CD14 cells, angiogenin showed the highest expression levels at day 1 postburn. With regard to burn wound neovascularization, angiogenin expression was partially correlated with CD14 blister cells in the burn fluids.

CONCLUSIONS

We provide the first report on the characterization of blister cells in burn fluids. Our data suggest that CD14 blister cells may play a role in burn wound neovascularization. Measurement of CD14 blister cells serves as a possible tool for assessing burn wound status.

HLAs: Key regulators of T-cell-mediated drug hypersensitivity

Adverse drug reactions (ADR) can be broadly categorised as either on-target or off-target. On-target ADRs arise as a direct consequence of the pharmacological properties of the drug and are therefore predictable and dose-dependent. On-target ADRs comprise the majority (>80%) of ADRs, relate to the drug's interaction with its known pharmacological target and are a result of a complex interplay of genetic and ecologic factors. In contrast, off-target ADRs, including immune-mediated ADRs (IM-ADRs), are due to unintended pharmacological interactions such as inadvertent ligation of host cell receptors or non-pharmacological interactions mediated through an adaptive immune response. IM-ADRs can be classified according to the primary immune cell involved and include B-cell-mediated (Gell-Coombs type I-III reactions) and T-cell-mediated (Gell-Coombs type IV or delayed hypersensitivity) reactions. IM-ADRs mediated by T cells are associated with phenotypically distinct clinical diagnoses and can vary from a mild delayed rash to a life-threatening cutaneous, systemic or organ disease, such as Stephen Johnson syndrome/toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms and drug-induced liver disease. T-cell-mediated ADRs are strongly linked to the carriage of particular HLA risk alleles which are in the case of abacavir hypersensitivity and HLA-B*57:01 has led to translation into the clinic as a routine screening test. In this review, we will discuss the immunogenetics and pathogenesis of IM-ADRs and how HLA associations inform both pre-drug screening strategies and mechanistic understanding.

Treatments for Severe Cutaneous Adverse Reactions

Severe cutaneous adverse reaction (SCAR) is life-threatening. It consists of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis (AGEP), and generalized bullous fixed drug eruptions (GBFDE). In the past years, emerging studies have provided better understandings regarding the pathogenesis of these diseases. These diseases have unique presentations and distinct pathomechanisms. Therefore, theoretically, the options of treatments might be different among various SCARs. However, due to the rarity of these diseases, sufficient evidence is still lacking to support the best choice of treatment for patients with SCAR. Herein, we will provide a concise review with an emphasis on the characteristics and treatments of each SCAR. It may serve as a guidance based on the current best of knowledge and may shed light on the directions for further investigations.

Severe erythema multiforme-type drug eruption controlled by tumor necrosis factor-α antagonist: A case study

Using a tumor necrosis factor-α antagonist, the present study successfully treated a case of severe erythema multiform-type drug eruption, which occurred following anti-Helicobacter pylori therapy. A 73-year-old female suffering from upper gastrointestinal bleeding and peptic-ulcer presented with an itchy rash, fever, an increase in leukocytes and eosinophils and lymphadenectasis following oral administration of amoxicillin. Following six subcutaneous injections of etanercept (initially 50 mg, then 25 mg every 3 days), the patient was deemed to have recovered. Following the first injection, the fever was under control. On day 2, the lesions were no longer expanding. On day 4, the rash was markedly less itchy, the swelling decreased, the erythema began to crust and mucosal secretions disappeared. On day 16, the patient was deemed to have recovered and was discharged from the hospital. Her peripheral blood eosinophil count continued to rise following the injection, peaking on day 9. Following this, the count declined slowly, but remained significantly higher than normal when the patient was discharged. The present case indicates that tumor necrosis factor-α antagonist is a safe, fast and effective treatment for severe drug eruption, but it is unable to prevent the rise of peripheral blood eosinophils.

Severe Delayed Drug Reactions: Role of Genetics and Viral Infections

Adverse drug reactions (ADRs) are a significant source of patient morbidity and mortality and represent a major burden to health care systems and drug development. Up to 50% of such reactions are preventable. Although many ADRs can be predicted based on the on-target pharmacologic activity, ADRs arising from drug interactions with off-target receptors are recognized. Off-target ADRs include the immune-mediated ADRs (IM-ADRs) and pharmacologic drug effects. In this review, we discuss what is known about the immunogenetics and pathogenesis of IM-ADRs and the hypothesized role of heterologous immunity in the development of IM-ADRs.

New Evidence Supporting Cyclosporine Efficacy in Epidermal Necrolysis

Sixty years after its original description by Sir Alan Lyell, epidermal necrolysis (from Stevens-Johnson syndrome to toxic epidermal necrolysis) seems finally amenable to a specific treatment in addition to essential symptomatic measures in specialized settings. A recently published systematic review and an article by Gonzales-Herrada et al. strongly suggest that cyclosporine is effective in reducing the risk of death.

Pharmacogenomic Advances in the Prediction and Prevention of Cutaneous Idiosyncratic Drug Reactions

Cutaneous idiosyncratic drug reactions (CIDRs) are usually unpredictable, ranging from mild maculopapular exanthema (MPE) to severe cutaneous adverse drug reactions (SCARs) such as drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Increasing evidence suggests that HLA alleles are strongly associated with drug-induced-CIDRs. The pathomechanisms for CIDRs include genetic polymorphisms affecting complex immune-specific HLA/drug antigen/T-cell receptor interactions and drug metabolism. Pharmacogenomic tests to prevent CIDRs have been widely implemented in clinical practice in recent years.

Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A Concise Review with a Comprehensive Summary of Therapeutic Interventions Emphasizing Supportive Measures

INTRODUCTION

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are two of the most severe dermatologic conditions occurring in the inpatient setting. There is a lack of consensus regarding appropriate management of SJS and TEN.

PURPOSE

The scientific literature pertaining to SJS and TEN (subsequently referred to as SJS/TEN) is summarized and assessed. In addition, an interventional approach for the clinician is provided.

METHODS

PubMed was searched with the key words: corticosteroids, cyclosporine, etanercept, intravenous immunoglobulin, Stevens-Johnson syndrome, and toxic epidermal necrolysis. The papers generated by the search, and their references, were reviewed.

RESULTS

Supportive care is the most universally accepted intervention for SJS/TEN. Specific guidelines differ from the care required for patients with thermal burns. Adjuvant therapies are utilized in most severe cases, but the data are thus far underwhelming and underpowered. Using systemic corticosteroids as sole therapy is not supported. A consensus regarding combined corticosteroids and intravenous immunoglobulin (IVIG) has not been reached. Data regarding IVIG, currently the standard of care for most referral centers, is conflicting. Newer studies regarding cyclosporine and tumor necrosis factor inhibitors are promising, but not powered to provide definitive evidence of efficacy. Data regarding plasmapheresis is equivocal. Thalidomide increases mortality.

CONCLUSION

Clinicians who manage SJS/TEN should seek to employ interventions with the greatest impact on their patients' condition. While supportive care measures may seem an obvious aspect of SJS/TEN patient care, providers should understand that these interventions are imperative and that they differ from the care recommended for other critically ill or burn patients. While adjuvant therapies are frequently discussed and debated for hospitalized patients with SJS/TEN, a standardized management approach is not yet clear based on the current data. Therefore, until further data are available, decisions regarding such treatments should be made on a case-by-case basis.

Severe Delayed Cutaneous and Systemic Reactions to Drugs: A Global Perspective on the Science and Art of Current Practice

Most immune-mediated adverse drug reactions (IM-ADRs) involve the skin, and many have additional systemic features. Severe cutaneous adverse drug reactions (SCARs) are an uncommon, potentially life-threatening, and challenging subgroup of IM-ADRs with diverse clinical phenotypes, mechanisms, and offending drugs. T-cell-mediated immunopathology is central to these severe delayed reactions, but effector cells and cytokines differ by clinical phenotype. Strong HLA-gene associations have been elucidated for specific drug-SCAR IM-ADRs such as Stevens-Johnson syndrome/toxic epidermal necrolysis, although the mechanisms by which carriage of a specific HLA allele is necessary but not sufficient for the development of many IM-ADRs is still being defined. SCAR management is complicated by substantial short- and long-term morbidity/mortality and the potential need to treat ongoing comorbid disease with related medications. Multidisciplinary specialist teams at experienced units should care for patients. In the setting of SCAR, patient outcomes as well as preventive, diagnostic, treatment, and management approaches are often not generalizable, but rather context specific, driven by population HLA-genetics, the pharmacology and genetic risk factors of the implicated drug, severity of underlying comorbid disease necessitating ongoing treatments, and cost considerations. In this review, we update the basic and clinical science of SCAR diagnosis and management.

Management of Toxic Epidermal Necrolysis with Plasmapheresis and Cyclosporine A: Our 10 Years' Experience

Background:

The management of toxic epidermal necrolysis (TEN) is controversial and there is no uniform strategy.

Objective:

To share our 10 years’ experience in treating severe TEN with a novel protocol based on the association of cyclosporine A and plasmapheresis.

Methods:

In this case series, we retrospectively collected and assessed the 12 cases of severe TEN treated from 2005 to 2015 at the Burn Unit of the University of Bari Policlinico hospital.

Results:

Average body surface area was 77; average SCORETEN was 4.3. The 12 patients had been treated with culprit drug withdrawal, systemic corticosteroids, and/or cyclosporine A with no response. The protocol was successfully administered in all 12 cases. Average time to response from protocol start was 4.9 days. Average time to remission from protocol start was 22 days; average hospital stay at our unit was 24.8 days. Four patients developed severe complications; 1 patient died. No complications linked to the protocol therapeutic measures were observed. The relatively small number of cases given the rarity of the condition is a limitation of this report.

Conclusion:

Our protocol based on the association of cyclosporine A and plasmapheresis is safe and efficacious in treating severe TEN.

Adverse Medication Reactions

Cutaneous adverse drug reactions (ADRs) are among the most frequent adverse reactions in patients receiving drug therapy. They have a broad spectrum of clinical manifestations, are caused by various drugs, and result from different pathophysiological mechanisms. Hence, their diagnosis and management is challenging.

Severe cutaneous ADRs comprise a group of diseases with major morbidity and mortality, reaching 30 % mortality rate in cases of Toxic Epidermal Necrolysis.

This chapter covers the terminology, epidemiology, pathogenesis and classification of cutaneous ADR, describes the severe cutaneous ADRs and the clinical and laboratory approach to the patient with cutaneous ADR and presents the translation of laboratory-based discoveries on the genetic predisposition and pathogenesis of cutaneous ADRs to clinical management guidelines.