Delayed drug hypersensitivity: models of T-cell stimulation

COVID-19 and severe cutaneous allergic reactions to sulfonamides

Background: Sulfonamides are associated with severe cutaneous adverse reactions (SCARs). Coronavirus disease 2019 (COVID-19) triggers an immune response, which may increase the likelihood of developing a hypersensitivity reaction. Objectives: We sought to explore the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the probability of developing SCARs and/or erythema multiforme (EM) reactions to sulfonamides. Methods: In the propensity score-matched cohort study by using the de-identified TriNetX Research data base, patients who had an exposure to antibiotic or non-antibiotic sulfonamides between March 1, 2020, and January 1, 2023, were divided into two groups based on the presence or absence of a previous COVID-19 infection within 6 months of starting the sulfonamide agent. The outcomes studied were the 30-day risk of developing SCARs or EM (Stevens-Johnson syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms, or EM) within 3 months of sulfonamide exposure. Cohorts were matched based on baseline demographics; malignant lymphoid neoplasms; human immunodeficiency virus; systemic lupus erythematosus; bone marrow transplantation; diabetes; psoriasis; seizures; gout; solid organ or stem cell transplantation; COVID-19 vaccination; and exposure to risk medications, including allopurinol, levetiracetam, carbamazepine, lamotrigine, oxcarbazepine, phenytoin, phenobarbital, abacavir, nevirapine, piroxicam, tenoxicam, or mexiletine. Results: When comparing 345,119 patients on sulfonamides and with previous COVID-19 to an equal number of sulfonamides users without a previous COVID-19, patients with COVID-19 had a lower risk of developing any form of SCARs (relative risk 0.39 [95% confidence interval, 0.26, 0.58]; p < 0.001). Conclusion: Previous SARS-CoV-2 infection seems to be associated with a lower probability of developing SCARs or EM among patients using sulfonamides.

Risk factors for drug hypersensitivity reactions in children

Drug hypersensitivity reactions are common in children. Risk factors predisposing to IgE-mediated drug allergies and delayed drug reactions are a matter of debate. Gender, age, previous reactions to the same drug or to another drug, reduced drug metabolism, chronic diseases, polypharmacy, drug doses are linked with the onset of hypersensitivity reactions in some children. Novel advances in genetic polymorphisms can rapidly change the approach to the prevention of reactions since gene testing can be a useful screening test for severe cutaneous adverse reactions. Viral infections may act as cofactors in susceptible individuals. Polypharmacy, high doses, repeated doses and parental route of administration are also risk factors. Clinicians should take into account risk factors to allow the risk-benefit balance to be maintained.

Delayed Type Hypersensitivity Reaction Induced By Liraglutide With Tolerance to Semaglutide

Liraglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist used for the management of type 2 diabetes and obesity. It was the first GLP-1 receptor agonist to be approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of obesity. To date, numerous skin adverse reactions to liraglutide have been reported, but data regarding hypersensitivity reactions are scarce, raising concerns about its safety and clinical management. We present the case of a 56-year-old female patient with class 3 obesity who was started on subcutaneous liraglutide (Saxenda) by her endocrinologist. One month after starting the aforementioned treatment, the patient presented well-defined, round, erythematous pruriginous plaques surrounding the injection site, around 24 hours after the drug administration. A liraglutide-induced, delayed-type hypersensitivity reaction was suspected, which could be subsequently confirmed by allergy testing and histopathological study. This paper explores the clinical use of liraglutide, the occurrence of hypersensitivity reactions, diagnosis, management, and implications for future research. Understanding and managing liraglutide hypersensitivity is crucial to ensuring the safety and efficacy of this medication.

Real-world safety of Levetiracetam: Mining and analysis of its adverse drug reactions based on FAERS database

INTRODUCTION

Levetiracetam is a relatively new and widely utilized anti-seizure medication; however, limited information is available regarding its adverse effects. This study aims to thoroughly investigate, evaluate, and present evidence on the safety profile of Levetiracetam, relying on data from the FDA Adverse Event Reporting System (FAERS) database to facilitate informed clinical decision-making.

METHODS

We employed various statistical measures, including Reporting Odds Ratio (ROR), Proportionate Reporting Ratio (PRR), and analysis by the Medicines and Healthcare Products Regulatory Agency (MHRA), to identify signals of adverse reactions associated with Levetiracetam. Positive signals consistent with Designated Medical Event (DME) were singled out for focused comparison and discussion.

RESULTS

The analysis of 26,182 adverse events linked to Levetiracetam as the primary suspected drug revealed 692 positive signals spanning 22 System Organ Classes (SOCs). Nervous system disorders were the most frequently reported, followed by psychiatric disorders, and general disorders and administration site conditions. 11 positive signals consistent with Preferred Terms (PTs) in DME were identified, predominantly concentrated in 6 SOCs. Among these, rhabdomyolysis, Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) exhibited relatively large values of A, ROR, and Chi-squared. Additionally, PTs related to spontaneous abortion, drug interaction, urethral atresia, ventricular septal defect, and atrial septal defect showed significant strength.

CONCLUSIONS

The study indicates that Levetiracetam carries a potential risk of causing rhabdomyolysis, SJS, TEN, DRESS as well as spontaneous abortion. Signals related to drug interaction, urethral atresia, ventricular septal defect, and atrial septal defect warrant heightened attention in clinical use.

Phenytoin-Induced Toxic Epidermal Necrolysis

Toxic epidermal necrolysis (TEN) is a rare fatal mucocutaneous blistering disorder that can have varied underlying triggers. The percentage of body surface area (BSA) that is impacted by erosive blistering is what separates it from Steven Johnson syndrome (SJS), both of which have the same underlying pathogenesis and are thought to exist on a continuum of disease with TEN being the more serious of the two. Medications are the most frequent cause of TEN/SJS and typically cause disease in both adults and children within eight weeks; however, the median exposure window is four days to four weeks. Nonsteroidal anti-inflammatory drugs, allopurinol, anticonvulsants including lamotrigine, phenytoin, levetiracetam and carbamazepine, antimicrobial sulfonamides, and the antiviral nevirapine are examples of medications that frequently cause TEN/SJS. Here, we are reporting a case of phenytoin-induced TEN highlighting the patient's excellent response to immunomodulating treatment despite 100% involvement of the BSA.

Bridging the gap between bench and clinic: the importance of understanding the mechanism of iodinated contrast media hypersensitivity

Since the advent of CT, iodinated contract media (ICM) has become one of the most regularly administered intravenous medications in clinical settings. Although considered generally safe, ICM is one of the most common causes of adverse drug reactions in clinical practice, accounting for more than 2 million adverse reactions worldwide. Currently, there are few useful tools to diagnose patient hypersensitivity, with the major limitation being the lack of consensus regarding the mechanisms of hypersensitivity to ICM. While there is an overwhelming abundance of literature pertaining to clinical features including incidence, symptomatology, and risk, few studies have further investigated the underlying mechanisms behind their clinical observations. Of the available literature discussing pathophysiology, most primary studies were completed over 20 years ago, since which the molecular characteristics of ICM have changed. Furthermore, many reviews mentioning pathophysiology fail to adequately emphasize the clinical importance of understanding the molecular pathways involved in hypersensitivity. In this review, we aim to emphasize the clinical relevance of pathophysiology as it relates to the prediction and diagnosis of hypersensitivity reactions to ICM. To this end, we will first briefly characterize hypersensitivity reactions to ICM with respect to epidemiology and clinical presentation. We will then present the existing evidence supporting various proposed mechanisms of hypersensitivity, highlighting the gaps that remain in the mechanistic delineation of both immediate and delayed reactions. Finally, we discuss the possibility of in vitro testing as a way to predict and diagnose hypersensitivity reactions, pending a more complete elucidation of mechanisms.

Hypersensitivity reactions to small molecule drugs

Drug hypersensitivity reactions induced by small molecule drugs encompass a broad spectrum of adverse drug reactions with heterogeneous clinical presentations and mechanisms. These reactions are classified into allergic drug hypersensitivity reactions and non-allergic drug hypersensitivity reactions. At present, the hapten theory, pharmacological interaction with immune receptors (p-i) concept, altered peptide repertoire model, and altered T-cell receptor (TCR) repertoire model have been proposed to explain how small molecule drugs or their metabolites induce allergic drug hypersensitivity reactions. Meanwhile, direct activation of mast cells, provoking the complement system, stimulating or inhibiting inflammatory reaction-related enzymes, accumulating bradykinin, and/or triggering vascular hyperpermeability are considered as the main factors causing non-allergic drug hypersensitivity reactions. To date, many investigations have been performed to explore the underlying mechanisms involved in drug hypersensitivity reactions and to search for predictive and preventive methods in both clinical and non-clinical trials. However, validated methods for predicting and diagnosing hypersensitivity reactions to small molecule drugs and deeper insight into the relevant underlying mechanisms are still limited.

Pre-validation study of spectrophotometric direct peptide reactivity assay (Spectro-DPRA) as a modified in chemico skin sensitization test method

Skin sensitization is induced when certain chemicals bind to skin proteins. Direct peptide reactivity assay (DPRA) has been adopted by the OECD as an alternative method to evaluate skin sensitization by assessing a substance's reaction to two model peptides. A modified spectrophotometric method, Spectro-DPRA, can evaluate skin sensitization, in a high throughput fashion, to obviate some limitations of DPRA. Pre-validation studies for Spectro-DPRA were conducted to determine transferability and proficiency, within- and between-laboratory reproducibility, and predictive ability based on GLP principles at three laboratories (AP, KTR, and KCL). All laboratories confirmed high (> 90%) concordance for evaluating the sensitivity induced by ten chemical substances. The concordance among the three tests performed by each laboratory was 90% for AP, 100% for KTR, and 100% for KCL. The mean accuracy of the laboratories was 93.3% [compared to the standard operating procedure (SOP)]. The reproducibility among the three laboratories was as high as 86.7%; the accuracy was 86.7% for AP, 100% for KTR, and 86.7% for KCL (compared to the SOP). An additional 54 substances were assessed in 3 separate labs to verify the prediction rate. Based on the result, 29 out of 33 substances were classified as sensitizers, and 19 out of 21 identified as non-sensitizers; the corresponding sensitivity, specificity, and accuracy values were 87.9%, 90.5%, and 88.9%, respectively. These findings indicate that the Spectro-DPRA can address the molecular initiating event with improved predictability and reproducibility, while saving time and cost compared to DPRA or ADRA.

In vitro cell-based models of drug-induced hepatotoxicity screening: progress and limitation

Drug-induced liver injury (DILI) is one of the major causes of post-approval withdrawal of therapeutics. As a result, there is an increasing need for accurate predictive in vitro assays that reliably detect hepatotoxic drug candidates while reducing drug discovery time, costs, and the number of animal experiments. In vitro hepatocyte-based research has led to an improved comprehension of the underlying mechanisms of chemical toxicity and can assist the prioritization of therapeutic choices with low hepatotoxicity risk. Therefore, several in vitro systems have been generated over the last few decades. This review aims to comprehensively present the development and validation of 2D (two-dimensional) and 3D (three-dimensional) culture approaches on hepatotoxicity screening of compounds and highlight the main factors affecting predictive power of experiments. To this end, we first summarize some of the recognized hepatotoxicity mechanisms and related assays used to appraise DILI mechanisms and then discuss the challenges and limitations of in vitro models.

Proteomic Profiling and T Cell Receptor Usage of Abacavir Susceptible Subjects

Type B adverse drug reactions (ADRs) represent a significant threat as their occurrence arises unpredictable and despite proper application of the drug. The severe immune reaction Abacavir Hypersensitivity Syndrome (AHS) that arises in HIV⁺ patients treated with the antiretroviral drug Abacavir (ABC) strongly correlates to the presence of the human leukocyte antigen (HLA) genotype HLA-B*57:01 and discriminates HLA-B*57:01⁺ HIV⁺ patients from ABC treatment. However, not all HLA-B*57:01⁺ HIV⁺ patients are affected by AHS, implying the involvement of further patient-specific factors in the development of AHS. The establishment of a reliable assay to classify HLA-B*57:01 carriers as ABC sensitive or ABC tolerant allowed to investigate the T cell receptor (TCR) Vβ chain repertoire of effector cells and revealed Vβ6 and Vβ24 as potential public TCRs in ABC sensitive HLA-B*57:01 carriers. Furthermore, distinct effects of ABC on the cellular proteome of ABC sensitive and tolerant volunteers were observed and suggest enhanced activation and maturation of dentritic cells (DC) in ABC sensitive volunteers. Analysis of ABC-naïve cellular proteomes identified the T cell immune regulator 1 (TCIRG1) as a potential prognostic biomarker for ABC susceptibility and the involvement of significantly upregulated proteins, particularly in peptide processing, antigen presentation, interferon (IFN), and cytokine regulation.

A review of hypersensitivity methods to detect immune responses to SARS-CoV-2

The investigation of the immune response after SARS-CoV-2 infection has been the goal of many researchers worldwide. The study of humoral immune responses and in vitro T cell production after infection requires the obtaining of individualized blood samples to test the presence of antibodies or activated T cells specific for the virus. In vitro T cell studies are especially troublesome due to the need for more specialized resources often outside the daily routine of clinical laboratories. For this reason the development of a simple and objective method to achieve these T cell studies is needed. In this manuscript we reviewed the hypersensitivity reactions, the theoretical basis and the historical background of delayed type hypersensitivity (DTH) which uses the principles of use of this test in the clinical setting for the past century. In the second part of the review, we focus on COVID adaptive immune responses, to understand the differences and challenges offered by this new application of DTH to investigate immune responses elicited after infection. In the last part of the review a vision provided for the use of this test to investigate the immunogenicity elicited by the vaccines. In our opinion, the clinical guidelines of immune assessment of SARS-CoV-2-infected or vaccinated individuals should include this simple and low-cost test to measure T-cell immunity. Rationale and improved vaccination schemes could be obtained after its implementation in the routine assessment of immunity in this pandemic situation.

Whole-blood 3-gene Signature as a Decision Aid for Rifapentine-based TB Preventive Therapy

Background

Systemic drug reaction (SDR) is a major safety concern with weekly rifapentine plus isoniazid for 12 doses (3HP) for latent tuberculosis infection (LTBI). Identifying SDR predictors and at-risk participants before treatment can improve cost-effectiveness of the LTBI program.

Methods

We prospectively recruited 187 cases receiving 3HP (44 SDRs and 143 non-SDRs). A pilot cohort (8 SDRs and 12 non-SDRs) was selected for generating whole-blood transcriptomic data. By incorporating the hierarchical system biology model and therapy–biomarker pathway approach, candidate genes were selected and evaluated using reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Then, interpretable machine learning models presenting as SHapley Additive exPlanations (SHAP) values were applied for SDR risk prediction. Finally, an independent cohort was used to evaluate the performance of these predictive models.

Results

Based on the whole-blood transcriptomic profile of the pilot cohort and the RT-qPCR results of 2 SDR and 3 non-SDR samples in the training cohort, 6 genes were selected. According to SHAP values for model construction and validation, a 3-gene model for SDR risk prediction achieved a sensitivity and specificity of 0.972 and 0.947, respectively, under a universal cutoff value for the joint of the training (28 SDRs and 104 non-SDRs) and testing (8 SDRs and 27 non-SDRs) cohorts. It also worked well across different subgroups.

Conclusions

The prediction model for 3HP-related SDRs serves as a guide for establishing a safe and personalized regimen to foster the implementation of an LTBI program. Additionally, it provides a potential translational value for future studies on drug-related hypersensitivity.

Unravelling the Proteomics of HLA-B*57:01+ Antigen Presenting Cells during Abacavir Medication

Type B adverse drug reactions (ADRs) are unpredictable based on the drug’s pharmacology and represent a key challenge in pharmacovigilance. For human leukocyte antigen (HLA)-mediated type B ADRs, it is assumed that the protein/small-molecule interaction alters the biophysical and mechanistic properties of the antigen presenting cells. Sophisticated methods enabled the molecular appreciation of HLA-mediated ADRs; in several instances, the drug molecule occupies part of the HLA peptide binding groove and modifies the recruited peptide repertoire thereby causing a strong T-cell-mediated immune response that is resolved upon withdrawal of medication. The severe ADR in HLA-B*57:01⁺ patients treated with the antiretroviral drug abacavir (ABC) in anti-HIV therapy is an example of HLA-drug-T cell cooperation. However, the long-term damages of the HLA-B*57:01-expressing immune cells following ABC treatment remain unexplained. Utilizing full proteome sequencing following ABC treatment of HLA-B*57:01⁺ cells, we demonstrate stringent proteomic alteration of the HLA/drug presenting cells. The proteomic content indisputably reflects the cellular condition; this knowledge directs towards individual pharmacovigilance for the development of personalized and safe medication.

Bullous pemphigoid: An immune disorder related to aging (Review)

Bullous pemphigoid (BP) is the most frequent subepidermal autoimmune blistering disease and is caused by autoantibodies directed against two principal antigens of the hemidesmosome, BP antigen 180 and BP antigen 230. The pathogenesis of BP is dependent upon the interaction between genetic predisposition, physiological skin alterations due to aging and specific triggers. Several triggers have already been reported to induce this disease and include drugs, thermal or electrical burns, surgical procedures, trauma, UV radiation, radiotherapy, chemicals and infections. Data from the current literature support the hypothesis that alterations of the skin barrier associated with aging increase individual susceptibility to these aforementioned triggers. Consequently, this has been reported to lead to the attack of autoantibodies, demonstrating the predilection of BP for the elderly population. The identification of triggering factors and comorbidities may aid in understanding the pathogenesis of BP and improve clinical management by encouraging their prompt recognition and removal. Moreover, the present review has indicated that current management of BP should be aimed at counteracting the detrimental effects of aging on the skin by restoring skin barrier integrity and maintaining cutaneous homeostasis, for example with systematic applications of topical emollients and photoprotection. This strategy could prove even more beneficial in the elderly, in which frequent comorbidities associated with age often narrow available immunosuppressive treatment options. Furthermore, the safety of treatment regimens may significantly affect outcome and prognosis.

Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A Review of Diagnosis and Management

Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin. They are associated with significant morbidity and mortality, and early diagnosis and treatment is critical in achieving favorable outcomes for patients. In this scoping review, Excerpta Medica dataBASE and PubMed were searched for publications that addressed recent advances in the diagnosis and management of the disease. Multiple proteins (galectin 7 and RIP3) were identified that are promising potential biomarkers for SJS/TEN, although both are still in early phases of research. Regarding treatment, cyclosporine is the most effective therapy for the treatment of SJS, and a combination of intravenous immunoglobulin (IVIg) and corticosteroids is most effective for SJS/TEN overlap and TEN. Due to the rare nature of the disease, there is a lack of prospective, randomized controlled trials and conducting these in the future would provide valuable insights into the management of this disease.

Oxidative Stress in Drug-Induced Liver Injury (DILI): From Mechanisms to Biomarkers for Use in Clinical Practice

Idiosyncratic drug-induced liver injury (DILI) is a type of hepatic injury caused by an uncommon drug adverse reaction that can develop to conditions spanning from asymptomatic liver laboratory abnormalities to acute liver failure (ALF) and death. The cellular and molecular mechanisms involved in DILI are poorly understood. Hepatocyte damage can be caused by the metabolic activation of chemically active intermediate metabolites that covalently bind to macromolecules (e.g., proteins, DNA), forming protein adducts-neoantigens-that lead to the generation of oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress, which can eventually lead to cell death. In parallel, damage-associated molecular patterns (DAMPs) stimulate the immune response, whereby inflammasomes play a pivotal role, and neoantigen presentation on specific human leukocyte antigen (HLA) molecules trigger the adaptive immune response. A wide array of antioxidant mechanisms exists to counterbalance the effect of oxidants, including glutathione (GSH), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), which are pivotal in detoxification. These get compromised during DILI, triggering an imbalance between oxidants and antioxidants defense systems, generating oxidative stress. As a result of exacerbated oxidative stress, several danger signals, including mitochondrial damage, cell death, and inflammatory markers, and microRNAs (miRNAs) related to extracellular vesicles (EVs) have already been reported as mechanistic biomarkers. Here, the status quo and the future directions in DILI are thoroughly discussed, with a special focus on the role of oxidative stress and the development of new biomarkers.

CD1a function in human skin disease

The high expression of CD1a on Langerhans cells in normal human skin suggests a central role for this lipid antigen presenting molecule in skin homeostasis and immunity. Although the lipid antigen presenting function of CD1a has been known for years, the physiological and pathological functions of the CD1a system in human skin remain incompletely understood. This review provides an overview of this active area of investigation, and discusses recent insights into the functions of CD1a, CD1a-restricted T cells, and lipid antigens in inflammatory and allergic skin disease. We include recent publications and work presented at the biennial CD1-MR1 EMBO workshop held in 2019 in Oxford, regarding lipids that increase and those that decrease T cell responses to CD1a.

Genome-wide Study Identifies Association between HLA-B∗55:01 and Self-Reported Penicillin Allergy

Hypersensitivity reactions to drugs are often unpredictable and can be life threatening, underscoring a need for understanding their underlying mechanisms and risk factors. The extent to which germline genetic variation influences the risk of commonly reported drug allergies such as penicillin allergy remains largely unknown. We extracted data from the electronic health records of more than 600,000 participants from the UK, Estonian, and Vanderbilt University Medical Center's BioVU biobanks to study the role of genetic variation in the occurrence of self-reported penicillin hypersensitivity reactions. We used imputed SNP to HLA typing data from these cohorts to further fine map the human leukocyte antigen (HLA) association and replicated our results in 23andMe's research cohort involving a total of 1.12 million individuals. Genome-wide meta-analysis of penicillin allergy revealed two loci, including one located in the HLA region on chromosome 6. This signal was further fine-mapped to the HLA-B∗55:01 allele (OR 1.41 95% CI 1.33-1.49, p value 2.04 × 10-31) and confirmed by independent replication in 23andMe's research cohort (OR 1.30 95% CI 1.25-1.34, p value 1.00 × 10-47). The lead SNP was also associated with lower lymphocyte counts and in silico follow-up suggests a potential effect on T-lymphocytes at HLA-B∗55:01. We also observed a significant hit in PTPN22 and the GWAS results correlated with the genetics of rheumatoid arthritis and psoriasis. We present robust evidence for the role of an allele of the major histocompatibility complex (MHC) I gene HLA-B in the occurrence of penicillin allergy.

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.

N-acetyltransferase 2 enzyme genotype-phenotype discordances in both HIV-negative and HIV-positive Nigerians

BACKGROUND

The N-acetyltransferase 2 (NAT2) enzyme has been understudied in Nigerians including genotype-phenotype association studies.

OBJECTIVE

The aim of this study was NAT2 haplotype identification and genotype-phenotype investigations in HIV-positive and HIV-negative Nigerians.

PATIENTS AND METHODS

Phenotypes included self-reported sulphonamide hypersensitivity survey, experimental and computational NAT2 phenotyping. The NAT2 gene was amplified by PCR. Gene sequencing used ABI 3730 and Haploview 4.2 for haplotype reconstruction. Genotype-phenotype analyses used the χ P-value and odds ratio with a 95% confidence interval.

RESULTS

Self-reported sulphonamide hypersensitivity showed a prevalence of 3.1 and 12.4% in HIV-positive and HIV-negative Nigerians, respectively. NAT2 genetic variants 191G>A, 282C>T, 341T>C, 481C>T, 590G>A, 803A>G and 857G>A were not significantly different between both groups (odds ratio=0.87; 95% confidence interval: 0.54-1.38, P=0.55). Nine haplotypes: NAT2*4, NAT2*12A, NAT2*13A, NAT2*5B, NAT2*6A, NAT2*7B, NAT2*5C, NAT2*14B and NAT2*14A had frequencies more than 1%, whereas NAT2*12B had 1.1% in the HIV-positive and 0.4% in the HIV-negative group. Overall, slow acetylator haplotypes made up 68%. The NAT2*12 signature single-nucleotide polymorphism was in high linkage disequilibrium with signature single-nucleotide polymorphism for NAT2*13 (D'=0.97, r=0.61) and NAT2*5 (D'=0.98, r=0.64). Genotype-phenotype association analysis showed haplotypes NAT2*13A, NAT2*5C, NAT2*7B and NAT2*14A to be associated strongly with the slow metabolic phenotype (P=0.002, 0.029, 0.032 and 0.050, respectively). Computational phenotypes were similar, with 30.9, 66 and 3.1% for slow, intermediate and rapid acetylators, respectively, among HIV-positive Nigerians and 31.2, 66.3 and 2.5% among the HIV-negative group. Overall, slow phenotypes made up 31%.

CONCLUSION

NAT2 haplotype frequencies are similar in Nigerians, irrespective of HIV status, but genotype-phenotype discordances exist.

Comparison of abacavir-specific effector and proliferating functions of CD8 T cells in abacavir-treated HIV-1 patients

Susceptibility to abacavir hypersensitivity (ABH) in HIV-1-positive patients is strongly linked to the carriage of HLA-B*57:01 and the potential mechanism includes drug-specific activation of cytokine producing CD8 T cells exclusively in individuals carrying HLA-B*57:01. Here, we report a detailed characterization of abacavir-induced functional response of CD8 T cells in HLA-B*57:01^pos individuals. Peripheral blood mononuclear cells (PBMNCs) from HLA-B*57:01^pos ABH^pos and HLA-B*57:01^neg ABH^neg individuals were stimulated with abacavir. Multicolor flow cytometry was performed to assess the cytokine (IFNγ) production and degranulation (CD107a expression) after 6-18 hr culture and to enumerate proliferating CD4/CD8 T cells by culturing carboxyfluorescein diacetate succinimidyl ester-loaded PBMNCs for 7 days. CD8 T cells from HLA-B*57:01^pos ABH^pos individuals were multifunctional: proliferating, IFNγ producing, degranulating (CD107a^pos ), and both degranulating and IFNγ producing (CD107a^pos IFNγ^pos ). Degranulating CD8 T cells in general and both degranulating and IFNγ producing CD8 T cells in particular dominated abacavir-specific immune response. All functional responses were partially blocked by addition of HLA-B*57:01-reactive Bw4 mAb, but not by non-HLA-B*57:01-reactive Bw6 mAb. In conclusion, the study demonstrates that abacavir-specific CD8 T-cell-restricted immune response in HLA-B*57:01^pos ABH^pos HIV-1 patients has multiple effector and proliferating functions, where the primary effector response appears to be the release of cytolytic granules. The findings have implications for immunotherapy of HLA-related drug hypersensitivities.

Human T cell response to CD1a and contact dermatitis allergens in botanical extracts and commercial skin care products

During industrialization, humans have been exposed to increasing numbers of foreign chemicals. Failure of the immune system to tolerate drugs, cosmetics, and other skin products causes allergic contact dermatitis, a T cell-mediated disease with rising prevalence. Models of αβ T cell response emphasize T cell receptor (TCR) contact with peptide-MHC complexes, but this model cannot readily explain activation by most contact dermatitis allergens, which are nonpeptidic molecules. We tested whether CD1a, an abundant MHC I-like protein in human skin, mediates contact allergen recognition. Using CD1a-autoreactive human αβ T cell clones to screen clinically important allergens present in skin patch testing kits, we identified responses to balsam of Peru, a tree oil widely used in cosmetics and toothpaste. Additional purification identified benzyl benzoate and benzyl cinnamate as antigenic compounds within balsam of Peru. Screening of structurally related compounds revealed additional stimulants of CD1a-restricted T cells, including farnesol and coenzyme Q2. Certain general chemical features controlled response: small size, extreme hydrophobicity, and chemical constraint from rings and unsaturations. Unlike lipid antigens that protrude to form epitopes and contact TCRs, the small size of farnesol allows sequestration deeply within CD1a, where it displaces self-lipids and unmasks the CD1a surface. These studies identify molecular connections between CD1a and hypersensitivity to consumer products, defining a mechanism that could plausibly explain the many known T cell responses to oily substances.

Trimethoprim-Sulfamethoxazole-Induced Aseptic Meningitis: A Rare Presentation of Commonly Used Antibiotic

Drug-induced aseptic meningitis is a rare medical condition with trimethoprim-sulfamethoxazole being one of the most common antimicrobial agents associated with it. Here, I report a case of a 56-year-old male who presented to a health care facility with shock and meningitis-like syndrome in two occasions, one year apart following an exposure to trimethoprim-sulfamethoxazole for treatment of skin/soft tissue infection. Investigations did not reveal an infectious etiology in the two presentations. The patient improved with supportive care and withdrawal of the offending agent. In the two admissions, the patient improved following stopping the offending drug in addition to supportive care. The diagnosis of trimethoprim-sulfamethoxazole-induced aseptic meningitis was the most likely explanation for this case. Trimethoprim-sulfamethoxazole-induced aseptic meningitis is rare although it is a life-threatening side effect of TMP/SMX; therefore, the clinicians should keep the diagnosis of drug-induced aseptic meningitis in the differential diagnosis of aseptic meningitis in the appropriate clinical setting as early withdrawal of the culprit drug and supportive measurements will lead to early recovery.

An Update on the Immunological, Metabolic and Genetic Mechanisms in Drug Hypersensitivity Reactions

Drug hypersensitivity reactions (DHRs) represent a major burden on the healthcare system since their diagnostic and management are complex. As they can be influenced by individual genetic background, it is conceivable that the identification of variants in genes potentially involved could be used in genetic testing for the prevention of adverse effects during drug administration. Most genetic studies on severe DHRs have documented HLA alleles as risk factors and some mechanistic models support these associations, which try to shed light on the interaction between drugs and the immune system during lymphocyte presentation. In this sense, drugs are small molecules that behave as haptens, and currently three hypotheses try to explain how they interact with the immune system to induce DHRs: the hapten hypothesis, the direct pharmacological interaction of drugs with immune receptors hypothesis (p-i concept), and the altered self-peptide repertoire hypothesis. The interaction will depend on the nature of the drug and its reactivity, the metabolites generated and the specific HLA alleles. However, there is still a need of a better understanding of the different aspects related to the immunological mechanism, the drug determinants that are finally presented as well as the genetic factors for increasing the risk of suffering DHRs. Most available information on the predictive capacity of genetic testing refers to abacavir hypersensitivity and anticonvulsants-induced severe cutaneous reactions. Better understanding of the underlying mechanisms of DHRs will help us to identify the drugs likely to induce DHRs and to manage patients at risk.

Application of Spectro-DPRA, KeratinoSens™ and h-CLAT to estimation of the skin sensitization potential of cosmetics ingredients

Ethical issues in animal toxicity testing have led to the search for alternative methods to determine the skin sensitization potential of cosmetic products. The emergence of ethical testing issues has led to the development of many alternative methods that can reliably estimate skin sensitization potentials. However, a single alternative method may not be able to achieve high predictivity due to the complexity of the skin sensitization mechanism. Therefore, several prediction assays, including both in chemico and in vitro test methods, were investigated and integrated based on the skin sensitization adverse outcome pathway. In this study, we evaluated three different integrated approaches to predict a human skin sensitization hazard using data from in vitro assays (KeratinoSens™ and human cell line activation test [h-CLAT]), and a newly developed in chemico assay (spectrophotometric direct peptide reactivity assay [Spectro-DPRA]). When the results of the in chemico and in vitro assays were combined, the predictivity of human data increased compared with that of a single assay. The highest predictivity was obtained for the approach in which sensitization potential was determined by Spectro-DPRA followed by final determination using the result of KeratinoSens™ and h-CLAT assays (96.3% sensitivity, 87.1% specificity, 86.7% positive predictive value, 96.4% negative predictive value and 91.4% accuracy compared with human data). While further optimization is needed, we believe this integrated approach may provide useful predictive data when determining the human skin sensitization potential of chemicals.

The Mechanistic Differences in HLA-Associated Carbamazepine Hypersensitivity

Drug hypersensitivity reactions that resemble acute immune reactions are linked to certain human leucocyte antigen (HLA) alleles. Severe and life-threatening Stevens Johnson Syndrome and Toxic Epidermal Necrolysis following treatment with the antiepileptic and psychotropic drug Carbamazepine are associated with HLA-B*15:02; whereas carriers of HLA-A*31:01 develop milder symptoms. It is not understood how these immunogenic differences emerge genotype-specific. For HLA-B*15:02 an altered peptide presentation has been described following exposure to the main metabolite of carbamazepine that is binding to certain amino acids in the F pocket of the HLA molecule. The difference in the molecular mechanism of these diseases has not been comprehensively analyzed, yet; and is addressed in this study. Soluble HLA-technology was utilized to examine peptide presentation of HLA-A*31:01 in presence and absence of carbamazepine and its main metabolite and to examine the mode of peptide loading. Proteome analysis of drug-treated and untreated cells was performed. Alterations in sA*31:01-presented peptides after treatment with carbamazepine revealed different half-life times of peptide-HLA- or peptide-drug-HLA complexes. Together with observed changes in the proteome elicited through carbamazepine or its metabolite these results illustrate the mechanistic differences in carbamazepine hypersensitivity for HLA-A*31:01 or B*15:02 patients and constitute the bridge between pharmacology and pharmacogenetics for personalized therapeutics.

Female Asthmatic Patients Have Higher Risk to Develop Gemifloxacin-Associated Skin Rash, Highlighting Unique Delayed Onset Characteristics

Gemifloxacin is a common oral antibiotic for lower respiratory tract infection worldwide. We noticed an uncommon delayed onset skin rash in patients who received Gemifloxacin. Therefore, we retrospectively reviewed all patients who received Gemifloxacin from 1 January 2011 to 31 May 2016 in a university-affiliated hospital in Taiwan. A total of 1358 patients were enrolled, of whom 36 (2.65%) had skin eruptions. The female patients had a significantly higher odds ratio (OR) 2.24 (95% confidence interval (CI) 1.11–4.53, p = 0.021) of having skin eruptions. A history of asthma was also a significant risk factor (OR 2.04, 95% CI = 1.01–4.14, p = 0.043). Female asthmatic patients had the highest risk of skin eruptions (10/129, 7.2%) with an adjusted OR up to 4.45 (95% CI = 1.81–10.93, p < 0.001) compared to male and non-asthmatic patients. Of note, up to 58.3% (21/36) of the patients experienced a skin rash after they had completed and stopped Gemifloxacin. The median onset time was on the second day (ranging one to five days) after completing treatment. We reported that female asthmatic patients have the highest risk of Gemifloxacin-associated skin eruptions in Asia and that they highlighted a unique delayed onset skin rash.

Antibiotic Hypersensitivity Mechanisms

Antibiotics are commonly prescribed to treat a variety of bacterial infections. As with all medications, hypersensitivity reactions may occur and clinicians should be able to recognize them accurately and recommend appropriate management. Antibiotic related hypersensitivity reactions may be one of four different types: Type I reactions, which are IgE mediated and may lead to anaphylaxis; Type II reactions that are antibody-mediated and may result in thrombocytopenia, neutropenia, or hemolytic anemia; Type III reaction that involves an immune complex formation such as vasculitis; and Type IV reactions that consist of four subtypes and typically include a rash of varying level of severity with or without systemic signs and symptoms. Herein, we describe the mechanisms of different types of allergic reactions to commonly prescribed antibiotics and offer recommendations for management. Further, we briefly refer to antibiotic reactions that mimic hypersensitivity reactions but are not immune mediated, such as pseudoallergies and serum sickness-like reactions.

Antimicrobial Desensitization: A Review of Published Protocols

Antimicrobial desensitization represents a last-line option for patients with no alternative therapies, where the benefits of this intensive process must outweigh the potential harm from drug exposure. The goal of antimicrobial desensitization procedures is to establish a temporary state of tolerance to drugs that may otherwise cause hypersensitivity reactions. While no universal antimicrobial desensitization protocols exist, this review critically analyzes previously published desensitization protocols. The purpose of this review is to provide a greater insight for clinicians and institutions to ensure desensitization procedures are efficacious while minimizing potential for patient harm. With an increasing rate of antimicrobial resistance and the critical need to preserve antimicrobial agents, desensitization may represent another option in our antimicrobial stewardship toolkit.

Tamoxifen-induced vasculitis

INTRODUCTION

Tamoxifen is a selective estrogen receptor modulator used widely for the treatment of breast cancer. Apart from its common adverse reactions such as endometrial cancer, deep vein thrombosis, pulmonary emboli, there are very few reports about its ability to cause vasculitis.

CASE REPORT

A 45-year-old woman who underwent modified radical mastectomy was started on tamoxifen. Six months later, she developed vasculitis which was confirmed by immunofluorescence-induced vasculitis in a pre-menopausal woman.

MANAGEMENT AND OUTCOME

Dapsone was used to relieve her symptoms for two weeks, but the lesions reappeared when dapsone was stopped. She continues to suffer from vasculitis as tamoxifen could not be discontinued.

DISCUSSION

This case report is important in order to draw attention towards this rare, but equally severe side effect of cutaneous vasculitis due to the most commonly used drug for breast cancer. In view of the absence of alternative medications for pre-menopausal women, it is necessary to have a strict monitoring of its adverse effects as well as more intensive research for a better agent.

High-throughput screening (HTS)-based spectrophotometric direct peptide reactivity assay (Spectro-DPRA) to predict human skin sensitization potential

Some cosmetic ingredients can act as a chemical hapten to induce an immune response; therefore, evaluating the sensitizing potential of cosmetic ingredients is essential. We previously developed a novel in chemico direct peptide reactivity assay involving a spectrophotometric evaluation (Spectro-DPRA) for animal skin sensitization tests (local lymph node assay; LLNA). Based on previous research, we expanded the test materials to confirm the effectiveness of the Spectro-DPRA method for predicting the animal skin sensitization potential, and further determined the feasibility of the method for estimating the human skin sensitization potential. Spectro-DPRA showed 83.1% or 89.1% accuracy compared to a conventional LLNA or prediction based on human data, respectively, with a combination model using both a cysteine peptide and lysine peptide cut-off. To identify the effect of the lipophilicity of a chemical on predicting the skin sensitization potential, we applied our prediction model to chemicals with a Log P_ow range of -1 to 4. Overall predictability was increased, and the accuracy compared to the LLNA and human data was 91.5% and 94.9%, respectively, in the combination cut-off prediction model. In conclusion, Spectro-DPRA serves as an easy, rapid, and high-throughput in chemico screening method with high accuracy to predict the human skin sensitization potential of chemicals.

Human leukocyte antigen-associated severe cutaneous adverse drug reactions: from bedside to bench and beyond

Despite their being uncommon, severe cutaneous adverse drug reactions (SCARs) result in a very great burden of disease. These reactions not only carry with them a high mortality (10%-50%) and high morbidity (60%) with severe ocular complications, alopecia, oral and dental complications and development of autoimmune diseases, but also create a substantial economic burden for patients' families and society. SCARs are, therefore, an important medical problem needing a solution in many countries, especially in Asia. The clinical spectrum of SCARs comprises Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS (drug rash with eosinophilia and systemic symptoms) (also known as drug hypersensitivity syndrome or drug-induced hypersensitivity syndrome) and acute generalised exanthematous pustulosis. Recent crucial advances in determining genetic susceptibility and understanding how T cells recognise certain medications or their metabolites via the major histocompatibility complex and the effects of cofactors, have led to the implementation of cost-effective screening programs enabling prevention in a number of countries, and to further understanding of the patho-mechanisms involved in SCARs and their significance. In this review, we document comprehensively the journey of SCARs from bedside to bench and outline future perspectives in SCARs research.

Developing pharmacogenetic screening methods for an emergent country: Vietnam

BACKGROUND

The finding of strong associations between certain human leukocyte antigen (HLA) genotypes and the development of severe cutaneous adverse drug reactions (SCARs), [for example, HLA-B*57:01 and abacavir (ABC), HLA-B*15:02 and carbamazepine (CBZ) and HLA-B*58:01 and allopurinol], has led to HLA screening being used to prevent SCARs. Screening has been shown to be of great benefit in a number of studies. Clinical translation from bench to bedside, however, depends upon the development of simple, rapid and cost-effective assays to detect these risk alleles. In highly populated developing countries such as Vietnam, where there is a high prevalence of HLA-B*15:02 and HLA-B*58:01 correlating with a high incidence of CBZ- and allopurinol-induced SCARs, the crucial factor in the implementation of comprehensive screening programs to detect these major risk HLA alleles is the availability of suitable assays.

BODY

We have summarized the role and economic benefits of HLA screening, reviewed published HLA screening methods used currently in pharmacogenetic screening and examined the advantages and disadvantages of assays developed specifically for use in screening for risk alleles in the prevention of HLA-associated SCARs in Vietnam.

CONCLUSION

The optimal approach we propose may serve as a template for the development of screening programs in other emergent countries.

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.

Identification of hepatotoxic and nephrotoxic potential markers of triptolide in mice with delayed-type hypersensitivity

Triptolide (TP) is the crucial active ingredient of Tripterygium glycoside tablets and has been shown to have a significant therapeutic effect on delayed-type hypersensitivity (DTH)-related diseases. However, due to its potential hepatotoxicity and nephrotoxicity, adverse reactions have often been observed in long-term treatment regimens. Therefore, it is meaningful to find metabolic markers for toxicity for early diagnosis. In this study, a feasible strategy using HPLC-HRMS method combined with multivariate statistical analysis to discover toxic potential markers of TP was developed. TP was used to treat a DTH mouse model at a therapeutic dose (45μg/kg) and toxic dose (900 μg/kg). The metabolic profiles of the liver, kidney and plasma were characterized by HPLC-Q/TOF MS. Significant differences in the metabolite profiles of the liver, kidney and plasma existed between the toxic and therapeutically dosed mice. Forty-six metabolites were identified and 27 of them may be related to toxicity based on a structure-toxicity prediction model. Using OPLS-DA analysis, the metabolite profiles between the two dose groups could be well distinguished. It was found that 18, 4 and 4 metabolic markers were altered in the liver, kidney and plasma, respectively; 15, 4 and 3 of these metabolic markers were predicted to be toxic. Two toxic markers detected both in mouse plasma and human liver microsomes following incubation with TP showed great potential as early diagnosis markers for TP hepatotoxicity and nephrotoxicity.

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.

Recent Advances in Drug-Induced Hypersensitivity Syndrome/Drug Reaction with Eosinophilia and Systemic Symptoms

Drug-induced hypersensitivity syndrome (DIHS), also termed as drug reaction with eosinophilia and systemic symptoms (DRESS), is a multiorgan systemic reaction characterized by a close relationship with the reactivation of herpes virus. Published data has demonstrated that among patients with DIHS/DRESS, 75–95% have leukocytosis, 18.2–90% show atypical lymphocytes, 52–95% have eosinophilia, and 75–100% have hepatic abnormalities. Histologically, eosinophils were observed less frequently than we expected (20%). The mainstay of DIHS/DRESS treatment is a moderate dose of systemic corticosteroids, followed by gradual dose reduction. In this review, we will emphasize that elevations in the levels of several cytokines/chemokines, including tumor necrosis factor- (TNF-) α and the thymus and activation-regulated chemokine (TARC/CCL17), during the early stage of disease, are good markers allowing the early recognition of HHV-6 reactivation. TNF-α and TARC levels also reflect therapeutic responses and may be useful markers of the DIHS disease process. Recently, the pathogenic mechanism of T-cell activation triggered by human leukocyte antigen- (HLA-) restricted presentation of a drug or metabolites was elucidated. Additionally, we recently reported that dapsone would fit within the unique subpocket of the antigen-recognition site of HLA-B^∗13:01. Further studies will render it possible to choose better strategies for DIHS prevention and therapy.

Sulfasalazine-Related Hypersensitivity Reactions in Patients With Rheumatic Diseases

BACKGROUND

Sulfasalazine (SSZ), which has an arylamine sulfonamide structure, is an anti-inflammatory drug used in the treatment of many rheumatic diseases. Various adverse effects have been reported related to SSZ. In the present study, we aimed to define the frequency of SSZ-related hypersensitivity reaction in patients with rheumatoid arthritis and ankylosing spondylitis.

METHODS

A total of 136 patients were included in this study. During follow-ups, reaction type, reaction duration, and drug doses were recorded in patients who developed hypersensitivity reactions. Drugs were discontinued in patients who developed reactions, and they were treated with antihistaminics and/or corticosteroids, according to requirements. Drug provocation tests with the drugs and aminosalicylic acid were performed in patients with negative skin prick test individually.

RESULTS

A total of 136 patients, with ages ranging from 19 to 71 years (mean, 41.97 [SD, 12.04] years), were included in the study. Hypersensitivity reactions according to the drug provocation test were found against SSZ in 12 patients (8.8%). The SSZ-related hypersensitivity reaction types were urticaria in 7 patients, urticaria and angioedema in 4 patients, and pruritus in 1 patient.

CONCLUSIONS

Sulfasalazine is widely used by rheumatologists in the treatment of rheumatic diseases. Whereas the frequency of sulfonamide-related hypersensitivity reactions was reported as 3.0% in the population, we detected hypersensitivity reactions to be 8.8% with SSZ usage in rheumatic diseases.

A docking model of dapsone bound to HLA-B*13:01 explains the risk of dapsone hypersensitivity syndrome

BACKGROUND

Dapsone (4,4'-diaminodiphenylsulfone) has been widely used for the treatment of infections such as leprosy. Dapsone hypersensitivity syndrome (DHS) is a major side effect, developing in 0.5-3.6% of patients treated with dapsone, and its mortality rate is ∼10%. Recently, human leukocyte antigen (HLA)-B*13:01 was identified as a marker of susceptibility to DHS.

OBJECTIVES

To investigate why HLA-B*13:01 is responsible for DHS from a structural point of view.

METHODS

First, we used homology modeling to derive the three-dimensional structures of HLA-B*13:01 (associated with DHS) and HLA-B*13:02 (not so associated despite strong sequence identity [99%] with HLA-B*13:01). Next, we used molecular docking, molecular dynamic simulations, and the molecular mechanics Poisson-Boltzman surface area method, to investigate the interactions of dapsone with HLA-B*13:01 and 13:02.

RESULTS

We found a crucial structural difference between HLA-B*13:01 and 13:02 in the F-pocket of the antigen-binding site. As Trp95 in the α-domain of HLA-B*13:02 is replaced with the less bulky Ile95 in HLA-B*13:01, we found an additional well-defined sub-pocket within the antigen-binding site of HLA-B*13:01. All three representative docking poses of dapsone against the antigen-binding site of HLA-B*13:01 used this unique sub-pocket, indicating its suitability for binding dapsone. However, HLA-B*13:02 does not seem to possess a binding pocket suitable for binding dapsone. Finally, a binding free energy calculation combined with a molecular dynamics simulation and the molecular mechanics Poisson-Boltzman surface area method indicated that the binding affinity of dapsone for HLA-B*13:01 would be much greater than that for HLA-B*13:02.

CONCLUSIONS

Our computational results suggest that dapsone would fit within the structure of the antigen-recognition site of HLA-B*13:01. This may change the self-peptides that bind to HLA-B*13:01, explaining why HLA-B*13:01 is a marker of DHS susceptibility.

Subcutaneous Toxicity of Agmatine in Rats

Objectives

The aim of this study was to investigate the effects of repetitive agmatine administration on sensorimotor gating in rats first but, as unexpected, ulcerative necrotic cutaneous lesions appeared, thus, the study was directed primarily to clarify these results.

Materials and Methods

In the first set of experiments, we administered agmatine (40, 80 and 160 mg/kg) and saline (control group) subcutaneously to male Wistar albino rats (n=8 for each group) for 14 consecutive days. Ulcerative necrotic cutaneous lesions appeared following the third day of agmatine administration. We decided to explore the potential toxic dermal effects of agmatine and conducted second set of experiments with two groups (n=8) to compare the effects of subcutaneous vs. intraperitoneal agmatine (80 mg/kg) injection to understand if the injection route determines the toxicity.

Results

Our results showed that prolonged subcutaneous but not intraperitoneal administration of agmatine leads to a delayed dermal reaction in rats. Histopathologic examination of skin samples revealed cutaneous aseptic necrosis at the injection site whereas blood tests were found to be normal.

Conclusion

This finding is important to point out the risks of prolonged subcutaneous administration of agmatine to rats within the concept of animal welfare. In addition, the results raise questions about the possible risks of over-the-counter use of agmatine among humans although the agent is taken via oral route.

A Review of the Pathogenesis of Toxic Epidermal Necrolysis

Toxic epidermal necrolysis (TEN) is a rare skin condition, most often drug-induced, known for its skin detachment and high mortality. In general, acute TEN is considered a T-cell mediated, type IV hypersensitivity disorder. It mostly results from a cumulative effect of risks from the drug structure, drug metabolism, HLA alleles and T cell clonotypes. However, the precise mechanism of TEN is still unknown. Apoptosis or necroptosis causes keratinocytes to lose their shape and adhesion, and necrosis predominates within a few days. Total epidermal necrosis separates the epidermis from the dermis. TEN is regarded as an immune reaction with predominantly CD8+ T lymphocytes, monocytes/macrophages, and natural killer cells. Impaired regulatory T-cells, T-helper 17 cells, cytotoxic granules such as perforin-granzyme and granulysin, tumor necrosis factor α, annexin, microRNA-18a-5p, and drug metabolites are all thought to be involved. From what is known, it can be assumed their mechanism is complex, and there is still much to be investigated. New findings will contribute to the identification of effective active methods of intervention.