Prospective evaluation of risk factors of cutaneous drug reactions to sulfonamides in patients with AIDS

Viral infections and drug hypersensitivity

Virus infections and T-cell-mediated drug hypersensitivity reactions (DHR) can influence each other. In most instances, systemic virus infections appear first. They may prime the reactivity to drugs in two ways: First, by virus-induced second signals: certain drugs like β-lactam antibiotics are haptens and covalently bind to various soluble and tissue proteins, thereby forming novel antigens. Under homeostatic conditions, these neo-antigens do not induce an immune reaction, probably because co-stimulation is missing. During a virus infection, the hapten-modified peptides are presented in an immune-stimulatory environment with co-stimulation. A drug-specific immune reaction may develop and manifest as exanthema. Second, by increased pharmacological interactions with immune receptors (p-i): drugs tend to bind to proteins and may even bind to immune receptors. Without viral infections, this low affine binding may be insufficient to elicit T-cell activation. During a viral infection, immune receptors are more abundantly expressed and allow more interactions to occur. This increases the overall avidity of p-i reactions and may even be sufficient for T-cell activation and symptoms. There is a situation where the virus-DHR sequence of events is inversed: in drug reaction with eosinophilia and systemic symptoms (DRESS), a severe DHR can precede reactivation and viremia of various herpes viruses. One could explain this phenomenon by the massive p-i mediated immune stimulation during acute DRESS, which coincidentally activates many herpes virus-specific T cells. Through p-i stimulation, they develop a cytotoxic activity by killing herpes peptide-expressing cells and releasing herpes viruses. These concepts could explain the often transient nature of DHR occurring during viral infections and the often asymptomatic herpes-virus viraemia after DRESS.

Pathology of drug hypersensitivity reactions and mechanisms of immune tolerance

Immune-mediated type IV adverse drug reactions are idiosyncratic in nature, generally not related to the primary or secondary pharmacology of the drug. Due to their complex nature and rarity, these iatrogenic reactions are seldom predicted or encountered during preclinical/early clinical development stages, and often precipitate upon exposure to wider populations (i.e. phase III onwards). They confer a burden on the healthcare sector in both a clinical and financial sense presenting a severe impediment to the drug discovery and development process. Research over the past 50 years has improved our understanding of these reactions markedly as both in vitro and in vivo studies have placed the role of the immune system, in particular; drug-responsive T cells, firmly in the spotlight as the mediators of these reactions. Indeed, the role of different populations of T cells in adverse events and the interaction of drug molecules with HLA proteins expressed on the surface of antigen-presenting cells is of considerable interest. Herein, this review examines the pathways of immune-mediated adverse events including the various T cell subtypes implicated and the mechanisms of T cell activation. Additionally, we address the enigma of immunological tolerance and explore the role tolerance plays in determination of susceptibility to such adverse events even in individuals carrying immunogenic liabilities.

Sulfonamide Hypersensitivity

Sulfonamides, particularly antimicrobial sulfonamides, have been implicated as a common cause of a spectrum of hypersensitivity reactions. Immediate IgE-mediated reactions have been reported but are much less common than delayed cutaneous reactions. Delayed cutaneous reactions range from benign exanthems to severe cutaneous reactions such as Stevens Johnson syndrome, toxic epidermal necrolysis, or drug reaction with eosinophilia and systemic symptoms. Sulfonamides can be subclassified as antimicrobial sulfonamides and non-antimicrobial sulfonamides, which are also distinguished by key structural differences, resulting in very low risk of cross-reactivity between these two subclasses. Immediate and delayed skin testing and in vitro testing remain limited as options in evaluating antimicrobial sulfonamide hypersensitivity. Drug challenges continue to play an important role in the evaluation of both immediate and delayed reactions, with a growing body of evidence for the safety of direct challenges regardless of human immunodeficiency virus infection status. While numerous "desensitization" protocols have been described for the management of antimicrobial sulfonamide hypersensitivity, there is limited evidence that such procedures are successful because of an induction of tolerance.

RNA expression profiling in sulfamethoxazole-treated patients with a range of in vitro lymphocyte cytotoxicity phenotypes

The lymphocyte toxicity assay (LTA) is a proposed surrogate marker of sulfonamide antibiotic hypersensitivity. In the LTA, peripheral blood mononuclear cells (PBMCs) undergo apoptosis more readily in hypersensitive versus tolerant patients when exposed to drug-hydroxylamine metabolites in vitro. The purpose of this study was to identify key gene transcripts associated with increased cytotoxicity from sulfamethoxazole-hydroxylamine in human PBMCs in the LTA. The LTA was performed on PBMCs of 10 patients hypersensitive to trimethoprim-sulfamethoxazole (HS) and 10 drug-tolerant controls (TOL), using two cytotoxicity assays: YO-PRO (n = 20) and MTT (n = 12). mRNA expression profiles of PBMCs, enriched for CD8+ T cells, were compared between HS and TOL patients. Transcript expression was interrogated for correlation with % cytotoxicity from YO-PRO and MTT assays. Correlated transcripts of interest were validated by qPCR. LTA results were not significantly different between HS and TOL patients, and no transcripts were found to be differentially expressed between the two groups. 96 transcripts were correlated with cytotoxicity by YO-PRO (r = ±.63-.75, FDR 0.188). Transcripts were selected for validation based on mechanistic plausibility and three were significantly over-expressed by qPCR in high cytotoxicity patients: multi-specific organic anion transporter C (ABCC5), mitoferrin-1 (SLC25A37), and Porimin (TMEM123). These data identify novel transcripts that could contribute to sulfonamide-hydroxylamine induced cytotoxicity. These include SLC25A37, encoding a mitochondrial iron transporter, ABCC5, encoding an arylamine drug transporter, and TMEM123, encoding a transmembrane protein that mediates cell death.

Structural Elements Recognized by Abacavir-Induced T Cells

Adverse drug reactions are one of the leading causes of morbidity and mortality in health care worldwide. Human leukocyte antigen (HLA) alleles have been strongly associated with drug hypersensitivities, and the causative drugs have been shown to stimulate specific T cells at the sites of autoimmune destruction. The structural elements recognized by drug-specific T cell receptors (TCRs) in vivo are poorly defined. Drug-stimulated T cells express TCRs specific for peptide/HLA complexes, but the characteristics of peptides (sequence, or endogenous or exogenous origin) presented in the context of small molecule drugs are not well studied. Using HLA-B*57:01 mediated hypersensitivity to abacavir as a model system, this study examines structural similarities of HLA presented peptides recognized by drug-specific TCRs. Using the crystal structure of HLA-B*57:01 complexed with abacavir and an immunogenic self peptide, VTTDIQVKV SPT5a 976-984, peptide side chains exhibiting flexibility and solvent exposure were identified as potential drug-specific T cell recognition motifs. Viral sequences with structural motifs similar to the immunogenic self peptide were identified. Abacavir-specific T cell clones were used to determine if virus peptides presented in the context of abacavir stimulate T cell responsiveness. An abacavir-specific T cell clone was stimulated by VTQQAQVRL, corresponding to HSV1/2 230-238, in the context of HLA-B*57:01. These data suggest the T cell polyclonal response to abacavir consists of multiple subsets, including T cells that recognize self peptide/HLA-B*57:01 complexes and crossreact with viral peptide/HLA-B*57:01 complexes due to similarity in TCR contact residues.

Hepatic expression profiles in retroviral infection: relevance to drug hypersensitivity risk

HIV‐infected patients show a markedly increased risk of delayed hypersensitivity (HS) reactions to potentiated sulfonamide antibiotics (trimethoprim/sulfamethoxazole or TMP/SMX). Some studies have suggested altered SMX biotransformation in HIV infection, but hepatic biotransformation pathways have not been evaluated directly. Systemic lupus erythematosus (SLE) is another chronic inflammatory disease with a higher incidence of sulfonamide HS, but it is unclear whether retroviral infection and SLE share risk factors for drug HS. We hypothesized that retroviral infection would lead to dysregulation of hepatic pathways of SMX biotransformation, as well as pathway alterations in common with SLE that could contribute to drug HS risk. We characterized hepatic expression profiles and enzymatic activities in an SIV‐infected macaque model of retroviral infection, and found no evidence for dysregulation of sulfonamide drug biotransformation pathways. Specifically, NAT1,NAT2,CYP2C8,CYP2C9,CYB5R3,MARC1/2, and glutathione‐related genes (GCLC,GCLM,GSS,GSTM1, and GSTP1) were not differentially expressed in drug naïve SIVmac239‐infected male macaques compared to age‐matched controls, and activities for SMX N‐acetylation and SMX hydroxylamine reduction were not different. However, multiple genes that are reportedly over‐expressed in SLE patients were also up‐regulated in retroviral infection, to include enhanced immunoproteasomal processing and presentation of antigens as well as up‐regulation of gene clusters that may be permissive to autoimmunity. These findings support the hypothesis that pathways downstream from drug biotransformation may be primarily important in drug HS risk in HIV infection.

Clinical analysis of HIV/AIDS patients with drug eruption in Yunnan, China

Drug eruption is the most common clinical presentation in patients with HIV/AIDS. The systemic clinical and risk factors associated with drug eruption remain unknown. A retrospective analysis in HIV/AIDS patients with drug eruption was carried out with demographic data, epidemiological data, clinical characteristics, laboratory data and follow-up data. The risk factors correlated with prognosis were assessed by case control analysis. A total of 134 out of 1817 HIV/AIDS patients (7.4%) presented drug eruptions. The major class of sensitizing drug was HAART drugs (47.7%), followed by antibiotics (47.0%). Nevirapine (39.6%) was the most common sensitizing drug in the HAART regimens. The patients received HAART or had allergic history were prone to develop drug eruption. The alanine aminotransferase, albumin, globulin, creatinine, blood urea nitrogen (BUN), lymphocytes, red blood cells (RBC) and eosinophils of the drug eruption patients were significantly different the control patients. The allergic history, opportunistic infection, viral load, CD4 cell count, high globulin and low albumin were the risk factors correlated with death in HIV/AIDS patients with drug eruption. It is proposed that patients with higher viral loads, higher globulin levels and lower white blood cells (WBC) should be given special attention for the prevention of complications and death.

Immunogenicity of trimethoprim/sulfamethoxazole in a macaque model of HIV infection

BACKGROUND

Sulfonamide hypersensitivity has a high incidence in HIV infection and correlates with low CD4+ counts, but the mechanisms are not understood. The aims of this study were to determine whether trimethoprim/sulfamethoxazole (TMP/SMX) led to SMX adduct formation, immunogenicity, or signs of drug hypersensitivity in SIV-infected rhesus macaques, and whether differences in antioxidants, pro-inflammatory mediators, or SMX disposition were predictive of drug immunogenicity.

METHODS

Nine macaques chronically infected with SIVmac239 and 7 non-infected controls were studied. Baseline blood ascorbate, glutathione, IFN-γ, LPS, sCD14, and cytochrome b₅ reductase measurements were obtained, macaques were dosed with TMP/SMX (120mg/kg/day p.o. for 14days), and SMX metabolites, lymph node drug adducts, drug-responsive T cells, and anti-SMX antibodies were measured.

RESULTS

Four of 9 of SIV-positive (44%), and 3 of 7 SIV negative (43%) macaques had drug-responsive T cells or antibodies to SMX. Two macaques developed facial or truncal rash; these animals had the highest levels of lymph node drug adducts. Antioxidants, pro-inflammatory mediators, and SMX metabolites were not predictive of drug immunogenicity; however, the Mamu DRB1*0401/0406/0411 genotype was significantly over-represented in immune responders.

CONCLUSIONS

Unlike other animal models, macaques develop an immune response, and possible rash, in response to therapeutic dosages of TMP/SMX. Studying more animals with CD4+ counts <200cells/μl, along with moderately restricted ascorbate intake to match deficiencies seen in humans, may better model the risk of SMX hypersensitivity in HIV-infection. In addition, the role of Mamu-DRB1 genotype in modeling drug hypersensitivity in retroviral infection deserves further study.

Genome-Wide Association Study in Immunocompetent Patients with Delayed Hypersensitivity to Sulfonamide Antimicrobials

Background

Hypersensitivity (HS) reactions to sulfonamide antibiotics occur uncommonly, but with potentially severe clinical manifestations. A familial predisposition to sulfonamide HS is suspected, but robust predictive genetic risk factors have yet to be identified. Strongly linked genetic polymorphisms have been used clinically as screening tests for other HS reactions prior to administration of high-risk drugs.

Objective

The purpose of this study was to evaluate for genetic risk of sulfonamide HS in the immunocompetent population using genome-wide association.

Methods

Ninety-one patients with symptoms after trimethoprim-sulfamethoxazole (TMP-SMX) attributable to “probable” drug HS based on medical record review and the Naranjo Adverse Drug Reaction Probability Scale, and 184 age- and sex-matched patients who tolerated a therapeutic course of TMP-SMX, were included in a genome-wide association study using both common and rare variant techniques. Additionally, two subgroups of HS patients with a more refined clinical phenotype (fever and rash; or fever, rash and eosinophilia) were evaluated separately.

Results

For the full dataset, no single nucleotide polymorphisms were suggestive of or reached genome-wide significance in the common variant analysis, nor was any genetic locus significant in the rare variant analysis. A single, possible gene locus association (COL12A1) was identified in the rare variant analysis for patients with both fever and rash, but the sample size was very small in this subgroup (n = 16), and this may be a false positive finding. No other significant associations were found for the subgroups.

Conclusions

No convincing genetic risk factors for sulfonamide HS were identified in this population. These negative findings may be due to challenges in accurately confirming the phenotype in exanthematous drug eruptions, or to unidentified gene-environment interactions influencing sulfonamide HS.

New approaches for predicting T cell-mediated drug reactions: A role for inducible and potentially preventable autoimmunity

Adverse drug reactions (ADRs) are commonplace and occur when a drug binds to its intended pharmacologic target (type A ADR) or an unintended target (type B ADR). Immunologically mediated type B ADRs, such as drug hypersensitivity syndrome, drug reaction with eosinophilia and systemic symptoms syndrome, and Stevens-Johnson syndrome/toxic epidermal necrolysis, can be severe and result in a diverse set of clinical manifestations that include fever and rash, as well as multiple organ failure (liver, kidney, lungs, and/or heart) in the case of drug hypersensitivity syndrome. There is increasing evidence that specific HLA alleles influence the risk of drug reactions. Several features of T cell-mediated ADRs are strikingly similar to those displayed by patients with autoimmune diseases like type I diabetes, such as strong HLA association, organ-specific adaptive immune responses, viral involvement, and activation of innate immunity. There is a need to better predict patient populations at risk for immunologically mediated type B ADRs. Because methods to predict type 1 diabetes by using genetic and immunologic biomarkers have been developed to a high level of accuracy (predicting 100% of subjects likely to progress), new research strategies based on these methods might also improve the ability to predict drug hypersensitivity.

Effectiveness of co-trimoxazole to prevent Plasmodium falciparum malaria in HIV-positive pregnant women in sub-Saharan Africa: an open-label, randomized controlled trial

BACKGROUND

Human immunodeficiency virus (HIV) and malaria during pregnancy cause substantial perinatal mortality. As co-trimoxazole (CMX) protects children and HIV-positive adults against malaria, we compared the effectiveness of daily CMX with sulfadoxine-pyrimethamine intermittent preventive treatment (IPT-SP) on malaria risk in HIV-positive pregnant women in a Plasmodium falciparum-endemic African area.

METHODS

 From January 2009 to April 2011, we included in a randomized noninferiority trial all HIV type 1-infected pregnant women (≤28 weeks' gestation, CD4 count ≥200 cells/µL, hemoglobin level ≥7 g/L) in 19 health centers in Togo. Women were randomly assigned to daily 800 mg/160 mg CMX, or IPT-SP. The primary outcome was the proportion of malaria-free pregnancies. Other outcomes included malaria incidence, parasitemia, placental malaria, anemia, and infants' birth weight.

RESULTS

Of 264 women randomly assigned to the CMX or IPT-SP group, 126 of 132 and 124 of 132, respectively, were included in the analysis. There were 33 confirmed cases of clinical malaria among 31 women in the CMX group, and 19 among 19 women in the IPT-SP group. Ninety-five of 126 (75.4%) women in the CMX group and 105 of 124 (84.7%) in the IPT-SP group remained malaria-free during their pregnancy (difference, 9.3%; 95% confidence interval [CI], -.53 to 19.1, not meeting the predefined noninferiority criterion). The incidence rate in intention-to-treat analysis was 108.8 malaria episodes per 100 person-years in CMX (95% CI, 105.4-112.2) and 90.1 in IPT-SP (95% CI, 86.8-93.4) (not significant). Prevalence of parasitemia was 16.7% in the CMX group vs 28% in the IPT-SP group (P = .02). Histology revealed 20.3% placental malaria in the CMX group vs. 24.6% in the IPT-SP group (not significant). Grade 3-4 anemia was more frequent in the CMX group (10% vs 4%; P = .008). No pregnant women died. Median birth weight was similar.

CONCLUSIONS

 Daily CMX was not noninferior to IPT-SP for preventing maternal malaria but safe and at least similar regarding parasitemia or placental malaria and birth outcomes. Clinical Trials Registration  ISRCTN98835811.

Human N-acetyltransferase 1 *10 and *11 alleles increase protein expression through distinct mechanisms and associate with sulfamethoxazole-induced hypersensitivity

OBJECTIVES

N-acetyltransferase 1 (NAT1) metabolizes drugs and environmental carcinogens. NAT1 alleles *10 and *11 have been proposed to alter protein level or enzyme activity compared with wild-type NAT1 *4 and to confer cancer risk, through uncertain pathways. This study characterizes regulatory polymorphisms and underlying mechanisms of NAT1 expression.

METHODS

We measured allelic NAT1 mRNA expression and translation, as a function of multiple transcription start sites, alternative splicing, and three 3'-polyadenylation sites in human livers (one of which was discovered in this study), B lymphocytes, and transfected cells. In a clinical study of 469 patients with HIV/AIDS treated with the NAT1/NAT2 substrate sulfamethoxazole (SMX), associations were tested between SMX-induced hypersensitivity and NAT1 *10 and *11 genotypes, together with known NAT2 polymorphisms.

RESULTS

NAT1 *10 and *11 were determined to act as common regulatory alleles accounting for most NAT1 expression variability, both leading to increased translation into active protein. NAT1 *11 (2.4% minor allele frequency) affected 3'-polyadenylation site usage, thereby increasing formation of NAT1 mRNA with intermediate length 3'-untranslated region (major isoform) at the expense of the short isoform, resulting in more efficient protein translation. NAT1 *10 (19% minor allele frequency) increased translation efficiency without affecting 3'-untranslated region polyadenylation site usage. Livers and B-lymphocytes with *11/*4 and *10/*10 genotypes displayed higher NAT1 immunoreactivity and NAT1 enzyme activity than the reference genotype *4/*4. Patients who carry *10/*10 and *11/*4 (fast NAT1 acetylators) were less likely to develop hypersensitivity to SMX, but this was observed only in individuals who are also carrying a slow NAT2 acetylator genotype.

CONCLUSION

NAT1 *10 and *11 significantly increase NAT1 protein level/enzyme activity, enabling the classification of carriers into reference and rapid acetylators. Rapid NAT1 acetylator status seems to protect against SMX toxicity by compensating for slow NAT2 acetylator status.

Evaluation of sulfonamide detoxification pathways in haematologic malignancy patients prior to intermittent trimethoprim-sulfamethoxazole prophylaxis

AIMS

Patients with haematologic malignancies have a reportedly high incidence of sulfamethoxazole (SMX) hypersensitivity. The objective of this study was to determine whether deficiencies in sulfonamide detoxification pathways, to include glutathione (GSH) and ascorbate (AA), and cytochrome b(5) (b5) and cytochrome b(5) reductase (b5R), were prevalent in these patients. A secondary pilot objective was to determine whether the incidence of drug hypersensitivity following intermittent trimethoprim-SMX (TMP-SMX) prophylaxis approached that reported for high dose daily regimens.

METHODS

Forty adult patients with haematologic malignancies (HM) and 35 healthy adults were studied; an additional 13 HM patients taking ascorbate supplements (HM-AA) were also evaluated. Twenty-two of 40 HM patients were prescribed and were compliant with TMP-SMX 960 mg three to four times weekly.

RESULTS

There were no significant differences between HM and healthy groups in plasma AA (median 37.2 µm vs. 33.9 µm) or red blood cell GSH (1.9 mmvs. 1.8 mm). However, plasma AA was correlated significantly with leucocyte b5/b5R reduction (r= 0.39, P= 0.002). Deficient b5/b5R activities were not found in HM patients. In fact, patients with chronic lymphocytic leukaemia or myeloma had significantly higher median activities (80.7 µmol mg(-1) min(-1)) than controls (18.9 µmol mg(-1) min(-1), P= 0.008). After 3-4 weeks of treatment, no patients developed SMX-specific T cells and only one patient developed rash.

CONCLUSIONS

Deficiencies of blood antioxidants and b5/b5R reduction were not found in this population with haematologic malignancies, and the development of skin rash and drug-specific T cells appeared to be uncommon with intermittent TMP-SMX prophylaxis.

Drug Induced Hypersensitivity and the HLA Complex

Drug-induced hypersensitivity reactions are of major concern and present a burden for national healthcare systems due to their often severe nature, high rate of hospital admissions and high mortality. They manifest with a wide range of symptoms and signs, and can be initiated by a wide range of structurally diverse chemical compounds. The pathophysiological mechanisms underlying hypersensitivity reactions are not well understood, but it is thought that they are immune mediated. MHC region on Chromosome 6 contains many genes with immune function. Classical MHC molecules are highly polymorphic cell surface glycoproteins whose function is to present peptide antigens to T cells. In addition to conferring protection from some diseases, HLA alleles are also associated with an increased risk of other diseases, including drug-induced hypersensitivity. Pharmacogenetic approach to predict the risk of drug-induced hypersensitivity has been established for several drugs. We will discuss the progress of hypersensitivity pharmacogenetics over the last few years and focus on current efforts of the international community to develop consortia which aim to standardize disease phenotypes and to identify affected individuals through international collaborations. In addition, we will discuss the clinical utility of HLA typing as predictive or diagnostic testing for drug-induced hypersensitivity.

Dermatopathological challenges in the human immunodeficiency virus and acquired immunodeficiency syndrome era

The histopathological assessment of cutaneous lesions is critical to the definitive diagnosis of many human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome-associated dermatoses, infections and tumours. Dermatopathological challenges stem mainly from the altered histopathological profile of established cutaneous entities compared with that in the HIV-unaffected population, the emergence of new diseases and the impact of therapeutic modalities on cutaneous lesions. This review focuses on some of these diagnostic dilemmas, with emphasis on the following challenges: (i) infective diagnostic pitfalls; (ii) itchy papular skin lesions; (iii) co-lesional comorbid diseases; (iv) drug-induced disease alterations; and (v) neoplastic and pseudoneoplastic proliferations. The drug-induced alterations include highly active antiretroviral therapy-associated disease modifications.

TNF, LTA, HSPA1L and HLA-DR gene polymorphisms in HIV-positive patients with hypersensitivity to cotrimoxazole

AIMS

Sulfamethoxazole in combination with trimethoprim (cotrimoxazole) is used for prophylaxis and treatment of several opportunistic infections in HIV-infected patients. It is associated with a high incidence of hypersensitivity reactions, which is thought to have an immune basis. Genetic polymorphisms in MHC are known to predispose to hypersensitivity reactions to a structurally diverse group of drugs in HIV-positive patients. The aim of the study was to determine whether functional polymorphisms in TNF, LTA, HSPA1L and HLA-DRB1 genes influence the risk of cotrimoxazole hypersensitivity in HIV-infected patients.

METHODS

We genotyped 136 HIV-positive patients with (n = 53) and without (n = 83) cotrimoxazole hypersensitivity using a combination of PCR-based techniques, including PCR-restriction fragment length polymorphisms, PCR-sequence specific oligonucleotides and real-time PCR. Genotypes and the haplotype frequencies were analyzed using the chi(2) test in the Haploview and CLUMP programs.

RESULTS

No statistically significant difference in SNP or haplotype frequencies were found in HIV-infected sulfamethoxazole hypersensitive patients compared with controls.

CONCLUSION

Our data show that MHC polymorphisms are not major predisposing factors for cotrimoxazole hypersensitivity, although we cannot exclude a minor contribution. An environmental factor (i.e., HIV infection) seems to predominate over any of the genetic factors so far investigated in increasing the risk of cotrimoxazole hypersensitivity.

Drug-induced hypersensitivity syndrome: clinical and biologic disease patterns in 24 patients

Drug-induced hypersensitivity syndrome (DIHS), also called drug rash with eosinophilia and systemic symptoms (DRESS), is a severe reaction usually characterized by fever, rash, and multiorgan failure, occurring 1-8 weeks after drug introduction. It is an immune-mediated reaction involving macrophage and T-lymphocyte activation and cytokine release, although no consensus has been reached as to its etiology. The skin, hematopoietic system, and liver are frequently involved. DIHS can mimic severe sepsis, viral infection, adult-onset Still disease (AOSD), or lymphoproliferation.We describe 24 consecutive patients with DIHS who were hospitalized between September 2004 and March 2008. Criteria for inclusion in this observational study were suspected drug reaction, eosinophilia >or=500/microL and/or atypical lymphocytes, involvement of at least 2 organs (skin being 1 of them), with suggestive chronology and exclusion of other diagnoses. Our cohort of 12 women and 12 men had a median age of 49 years (range, 22-82 yr), and 11 had skin phototype V or VI. Patients with mild or no rash were immunocompromised (7/24)- defined as treatment with prednisone (>or=10 mg/d) and another immunosuppressant drug, or human immunodeficiency virus infection. All patients were febrile (>38 degrees C), 14 had localized or generalized edema, 7 had pharyngitis, 8 had lymphadenopathy, 22 had hepatitis, 4 had nephritis, 2 had noninfectious and nonlithiasic angiocholitis or cholecystitis. Ten patients were hypotensive, 5 of whom had associated laboratory signs and/or imaging findings suggestive of acute myocardial dysfunction. Half of the patients had hemogram abnormalities, including eosinophilia. Nine DIHS patients fulfilled the Fautrel criteria for AOSD diagnosis, including glycosylated ferritin <20% in 4/11, with or without laboratory characteristics of hemophagocytosis. Twenty DIHS episodes occurred during the less sunny months of October to March.We determined 25-hydroxyvitamin D3 (25[OH]D3) levels in 18 patients and found that 9 patients had vitamin D deficiency (<25 nmol/L or <10 microg/L) and 5 had vitamin D insufficiency (25-50 nmol/L). Moreover, 25(OH)D3 levels were inversely correlated with ferritin values. After culprit-drug withdrawal, outcomes were favorable for all patients, including those with cardiac abnormalities under slow tapering of glucocorticoids.We recommend looking for the frequent but underdiagnosed hypersensitivity myocarditis with noninvasive diagnostic tools, such as N-terminal probrain natriuretic peptide, and promptly withdrawing the culprit drug and starting glucocorticoids. Vitamin D deficiency might be a DIHS risk or severity factor, especially for patients with high skin phototype and during the winter. Because DIHS clinical and laboratory patterns share similarities with AOSD and hemophagocytosis, DIHS should be included in their differential diagnoses.

Spectrum of skin disorders in human immunodeficiency virus-infected patients in Singapore and the relationship to CD4 lymphocyte counts

BACKGROUND

Skin disorders are extremely common and cause significant morbidity in human immunodeficiency virus (HIV)-infected individuals. There are few data on their prevalence and association with CD4 counts in Asians.

AIM

To evaluate the prevalence of skin disorders in ambulatory HIV-infected individuals attending a specialized skin clinic in Singapore and the association with the degree of immunosuppression.

METHODS

A cross-sectional study on skin disorders in HIV-positive outpatients in the Communicable Disease Centre of Singapore was performed. The association between skin disease prevalence and CD4 count was evaluated using logistic regression.

RESULTS

Ninety-six patients (male : female, 8 : 1) were enrolled. The most common mode of HIV transmission was heterosexual (75%), followed by homosexual/bisexual contacts (22%), and intravenous drug abuse (3%). The distribution of patients in terms of current CD4 cell counts was as follows: 38.5% with less than 50 x 10(6)/L, 25% with between 50 and 199/microL, and 36.5% with at least 200 x 10(6)/L. The most common skin disorder was pruritic papular eruption (PPE) of HIV infection (31 cases), followed by psoriasis (24), seborrheic dermatitis (18), xerosis (17), herpes simplex (17), and adverse drug eruptions (17). A CD4 cell count of less than 200 x 10(6)/L was significantly associated with a higher number of skin disorders (P = 0.002) and the development of psoriasis [odds ratio (OR), 8.97; 95% confidence interval (CI), 1.70-47.16; P = 0.010], PPE (OR, 3.40; 95% CI, 1.21-9.53; P = 0.020), and adverse drug eruption (OR, 5.83; 95% CI, 1.21-28.00; P = 0.028).

CONCLUSIONS

A preponderance of inflammatory dermatoses and an absence of skin tumors characterized this study. A low CD4 cell count was associated with a higher number of skin disorders and an increased incidence of PPE, psoriasis, and adverse drug eruptions.

Idiosyncratic adverse reactions to antiepileptic drugs

Idiosyncratic drug reactions may be defined as adverse effects that cannot be explained by the known mechanisms of action of the offending agent, do not occur at any dose in most patients, and develop mostly unpredictably in susceptible individuals only. These reactions are generally thought to account for up to 10% of all adverse drug reactions, but their frequency may be higher depending on the definition adopted. Idiosyncratic reactions are a major source of concern because they encompass most life-threatening effects of antiepileptic drugs (AEDs), as well as many other reactions requiring discontinuation of treatment. Based on the underlying mechanisms, idiosyncratic reactions can be differentiated into (1) immune-mediated hypersensitivity reactions, which may range from benign skin rashes to serious conditions such as drug-related rash with eosinophilia and systemic symptoms; (2) reactions involving unusual nonimmune-mediated individual susceptibility, often related to abnormal production or defective detoxification of reactive cytotoxic metabolites (as in valproate-induced liver toxicity); and (3) off-target pharmacology, whereby a drug interacts directly with a system other than that for which it is intended, an example being some types of AED-induced dyskinesias. Although no AED is free from the potential of inducing idiosyncratic reactions, the magnitude of risk and the most common manifestations vary from one drug to another, a consideration that impacts on treatment choices. Serious consequences of idiosyncratic reactions can be minimized by knowledge of risk factors, avoidance of specific AEDs in subpopulations at risk, cautious dose titration, and careful monitoring of clinical response.

Soluble FAS ligand: a discriminating feature between drug-induced skin eruptions and viral exanthemas

The clinical spectrum of cutaneous eruptions comprises benign variants like maculopapular rashes (MPRs) and potentially life-threatening events such as toxic epidermal necrolysis (TEN). Apoptosis of keratinocytes is a common histopathological feature of all these drug eruptions. As in skin lesions of TEN and Stevens-Johnson syndrome patients, apoptosis of keratinocytes is often accompanied by an only sparse cellular infiltrate, a soluble fatty acid synthetase ligand (sFASL)-mediated mechanism of keratinocyte cell death is postulated. In MPR patients, evidence for the occurrence of a similar process could not be established so far. We therefore examined sera and lesional skin sections from patients with clinical variants of drug eruptions for FASL expression using a sandwich ELISA and immunohistochemistry, respectively. As controls, healthy persons and patients with other inflammatory skin diseases such as viral exanthema were analyzed. Elevated levels of FASL were detected not only in TEN patients but also in sera and lesional skin of patients with MPR. In contrast, sFASL was repeatedly negative in all viral exanthemas and healthy controls tested. Thus, determination of sFASL serum concentration may represent a discriminating tool between drug rashes and viral exanthemas.

DRESS syndrome associé à une pan-uvéite bilatérale : à propos d’un cas

INTRODUCTION

DRESS syndrome (drug rash or reaction with eosinophilia and systemic symptoms) is a rare but life-threatening drug hypersensitivity syndrome with a potential viral cofactor. The syndrome is characterized by rash, fever, hematological disorders (eosinophilia, lymphocytosis), and systemic symptoms (adenopathy, multiorgan involvement).

CASE REPORT

We report the first description of acute bilateral panuveitis with elevated intraocular pressure associated with anticonvulsant-induced DRESS syndrome, hypogammaglobulinemia, and HHV-6 reactivation in a 63-year-old-woman. Complete general and ophthalmological recovery was obtained 4 weeks after the end of anticonvulsant drug exposure without corticosteroid prescription, with the patient remaining free of disease after 6 months.

DISCUSSION

Our data suggest that uveitis may be one of multivisceral involvements described in drug hypersensitivity syndrome. The data also suggest that HHV-6 may play a role in the complex pathogenesis of DRESS as well as in the development of immune inflammatory disorders such as bilateral panuveitis with elevated intraocular pressure and alteration of retinal and choroidal circulation in this patient.

Roles of endogenous ascorbate and glutathione in the cellular reduction and cytotoxicity of sulfamethoxazole-nitroso

Sulfamethoxazole (SMX) is an effective drug for the management of opportunistic infections, but its use is limited by hypersensitivity reactions, particularly in HIV-infected patients. The oxidative metabolite SMX-nitroso (SMX-NO), is thought to be a proximate mediator of SMX hypersensitivity, and can be reduced in vitro by ascorbate or glutathione. Leukocytes from patients with SMX hypersensitivity show enhanced cytotoxicity from SMX metabolites in vitro; this finding has been attributed to a possible "detoxification defect" in some individuals. The purpose of this study was to determine whether variability in endogenous ascorbate or glutathione could be associated with individual differences in SMX-NO cytotoxicity. Thirty HIV-positive patients and 23 healthy control subjects were studied. Both antioxidants were significantly correlated with the reduction of SMX-NO to its hydroxylamine, SMX-HA, by mononuclear leukocytes, and both were linearly depleted during reduction. Controlled ascorbate supplementation in three healthy subjects increased leukocyte ascorbate with no change in glutathione, and significantly enhanced SMX-NO reduction. Ascorbate supplementation also decreased SMX-NO cytotoxicity compared to pre-supplementation values. Rapid reduction of SMX-NO to SMX-HA was associated with enhanced direct cytotoxicity from SMX-NO. When forward oxidation of SMX-HA back to SMX-NO was driven by the superoxide dismutase mimetic, Tempol, SMX-NO cytotoxicity was increased, without enhancement of adduct formation. This suggests that SMX-NO cytotoxicity may be mediated, at least in part, by redox cycling between SMX-HA and SMX-NO. Overall, these data indicate that endogenous ascorbate and glutathione are important for the intracellular reduction of SMX-NO, a proposed mediator of SMX hypersensitivity, and that redox cycling of SMX-HA to SMX-NO may contribute to the cytotoxicity of these metabolites in vitro.

Immune response to xenobiotics in the skin: from contact sensitivity to drug allergy

Skin is the most frequent target of adverse drug reactions. These cutaneous drug reactions (CDRs) show varied clinical manifestations ranging from mildly discomforting rashes to life-threatening Stevens-Johnson syndrome or toxic epidermal necrolysis. Most CDRs appear to be immune mediated, although the mechanism by which they are initiated remains unclear. In this review, current knowledge of the mechanisms by which xenobiotics provoke immune responses in the skin after epicutaneous administration and how similar reactions may occur after systemic routes are summarised. This review also discusses a variety of genetic or environmental factors that may determine the susceptibility of individuals towards immune responses in skin following drug exposure.

Immune mechanisms in drug allergy

Clinicians had suspected for years that drug eruptions were probably mediated by immune mechanisms because their timing suggested sensitization and specific immunologic memory rather than direct toxicity. An immune response to medications was also demonstrated by positive skin tests and by several types of in vitro tests that evidenced immediate or delayed hypersensitivity. In the last decade several teams of researchers obtained in vitro drug-specific human T-cell clones, in a variety of clinical types of drug eruptions. These clones were produced from blood or skin mononuclear cells of patients with a history of drug reaction by stimulation in vitro with drug. They were either of CD4 or CD8 phenotypes. Drug specific clones were stimulated by the parent drug much more often than by reactive metabolites. That challenged the classical "hapten hypothesis" that the immune response was initiated by reactive metabolites combined to self proteins. The medication usually stimulated specific T-cells after non-covalent binding to major histocompatibility (MHC) molecules on antigen presenting cells. In toxic epidermal necrolysis, T-lymphocytes present at the site of lesions, exhibited a drug specific cytotoxicity against autologous target cells, or allogeneic cells that shared the same HLA than autologous cells. This MHC class I restriction and mediation of death by perforin/granzyme release, is the classical behavior of cytotoxic T lymphocytes, like those operating in the reject of a transplanted organ. MHC restriction could explain the key role of HLA genes as predisposing factors to severe drug reactions. A strong association between HLA and hypersensitivity to abacavir, SJS or TEN to carbamazepine or allopurinol has been recently demonstrated. Resemblance to graft rejection points to the possible therapeution value of immuno suppressive agents. Most drug eruptions appear to result from T-cell mediated delayed hypersensitivity. The secondary activation of different cascades of cytokines, may contribute to the heterogeneity of clinical presentations.

Role of bioactivation in drug-induced hypersensitivity reactions

Drug-induced hypersensitivity reactions are a major problem in both clinical treatment and drug development. This review covers recent developments in our understanding of the pathogenic mechanisms involved, with special focus on the potential role of metabolism and bioactivation in generating a chemical signal for activation of the immune system. The possible role of haptenation and neoantigen formation is discussed, alongside recent findings that challenge this paradigm. Additionally, the essential role of costimulation is examined, as are the potential points whereby costimulation may be driven by reactive metabolites. The relevance of local generation of metabolites in determining the location and character of a reaction is also covered.

Une nouvelle cause de cholangite intra et extra-hépatique : le syndrome d’hypersensibilité médicamenteuse ou DRESS

The DRESS (Drug Rash with Eosinophilia and Systemic Symptoms) corresponds to a drug reaction generally including cutaneous eruption, fever, hematologic abnormalities such as eosinophilia and atypical lymphocytosis and one or more specific visceral lesions specially in the liver. We report a case of drug hypersensitivity syndrome or DRESS associated with intra and extra-hepatic biliary lesions. This syndrome was associated with sulfasalazine and naproxene therapy. A reactivation of HHV6 was documented in the continuations of the DRESS and could play a role in the symptomms.

Arzneimittelexantheme bei Therapie der HIV-Infektion mit Efavirenz und Nevirapin

Efavirenz and nevirapine are frequently used drugs in antiretroviral therapy. Rashes are common side effects of these drugs. In this study, we examined the characteristics of efavirenz- and nevirapine-associated rashes. This prospective nonrandomized multicenter study included 662 HIV-infected patients (efavirenz: 325, nevirapine: 337) to determine incidence, duration, cross-reactivity, and outcome upon reexposure. Of the treated patients, 4.5% (n=30) developed rashes (nevirapine: 2.4% and efavirenz: 6.4%). In four patients treatment was not interrupted. Three patients were re-exposed to the initial drug without any side effects. Therapy with nevirapine or efavirenz does not have to be interrupted if rashes exhibit no blistering, mucosal manifestations, or systemic signs.

Prevention of toxic epidermal necrolysis by regulatory T cells

To analyze immunoregulation of autoreactive T cells specific for epidermal skin antigens, we crossed transgenic mice expressing ovalbumin selectively in keratinocytes under the keratin 5 promoter (K5-mOVA) with mice expressing a K(b)-restricted OVA-specific T cell receptor transgene (OT-I). In athymic double-transgenic mice, OT-I cells developed extrathymically and, at 8-12 weeks of age, initiated severe epidermal damage mimicking toxic epidermal necrolysis (TEN). In contrast, euthymic double-transgenic mice showed thymic deletion of OT-I cells, had few of these cells in the periphery, and never developed skin changes mimicking TEN. Adoptive transfer of OT-I cells isolated from euthymic double-transgenic mice induced TEN in athymic K5-mOVA single-transgenic mice. This spontaneous disease in athymic double-transgenic mice was prevented by transferring lymph node cells from euthymic mice, but was not prevented when CD4(+) or CD25(+) cells were depleted from this population. Although purified CD4(+)CD25(+) cells scarcely prevented the skin disease induced by adoptive transfer of OT-I cells, they efficiently prevented the disease when co-transferred with CD11c(+) dendritic cells. These results suggested that thymus-derived regulatory T cells cooperate with CD11c(+) dendritic cells to prevent life-threatening skin damage such as TEN.

Hypersensitivity of HIV-1-Infected Cells to Reactive Sulfonamide Metabolites Correlated to Expression of the HIV-1 Viral Protein Tat

Impairment of human immunodeficiency virus (HIV)-infected cells to deal with reactive drug metabolites may be a mechanism for the increased rate of adverse drug reactions seen in AIDS. HIV Tat protein expression may be associated with increased oxidative stress within HIV-infected cells. To determine the relationship between expression of HIV Tat and sensitivity to reactive drug metabolites, we studied toxicity of sulfamethoxazole (SMX) and its reactive hydroxylamine intermediate (SMX-HA) in lymphocytes transfected with the HIV tat gene. Over a concentration range from 0 to 400 microM SMX-HA, there was a significant concentration-dependent increase in cell death in transfected cell lines expressing Tat compared with controls. Jurkat T cells transfected with a dose-dependent inducible tat gene showed increased toxicity in response to SMX-HA as more Tat expression was induced. Enhanced sensitivity to SMX-HA was accompanied by significantly lower concentrations of total intracellular glutathione compared with controls (P < 0.05). Sensitivity to reactive drug metabolites in HIV-infected cells seems to be mediated by the viral protein Tat.

Cutaneous manifestations of human immunodeficiency virus infection in Taiwan

Cutaneous manifestations are common and often the presenting feature of human immunodeficiency virus (HIV) infection, but a comprehensive study of HIV-associated skin lesions is not available in Taiwan. We reviewed all skin lesions in all HIV patients diagnosed in our department between 1990 and 1998 to document the spectrum of skin manifestations, the frequency of each disorder, and their relationship with CD4 counts. A total of 64 HIV patients were studied, including 38 with acquired immunodeficiency syndrome (AIDS) (CD4 < 200 x 10(6) cells/L) and 26 who had not developed AIDS (non-AIDS). There were 142 episodes of skin conditions representing 25 different skin diseases, including oral candidiasis (15% in non-AIDS vs 71% in AIDS patients), drug eruptions, herpes simplex, seborrheic dermatitis, dermatophytosis, herpes zoster, secondary syphilis, condyloma acuminatum, Kaposi's sarcoma (16% among AIDS patients), hairy leukoplakia, and molluscum contagiosum (13% among AIDS patients), in decreasing order. Several unusual cases are briefly described, including verrucous herpes infection, condyloma-like molluscum contagiosum, and AIDS-associated pigmented erythroderma. In our study, 70% of all HIV patients had skin diseases, with an average of 2.2 conditions per patient (3.2 in AIDS patients vs 0.7 in non-AIDS patients; p < 0.001). A broad spectrum of HIV-associated skin diseases was observed in our series. The frequency of HIV-associated skin disease was 92% in AIDS patients and 39% in non-AIDS patients; 78% of skin lesions in AIDS patients were diagnosed when CD4 counts were below 100 x 10(6) cells/L.

Palpable arciform migratory erythema in an HIV patient, a CD8+ pseudolymphoma

BACKGROUND

Palpable arciform migratory erythema (PAME) is characterized by large, elevated, reddish annular lesions localized on the upper trunk. As its infiltrate consists predominantly of dense infiltrates of CD4+ lymphocytes with polyclonal T-cell receptor (TCR) gene rearrangement, it has been grouped as a rare member of the T-cell pseudolymphomas.

METHODS

We performed histology, immunophenotyping, and TCR-gamma gene rearrangement studies in an human immunodeficiency virus (HIV)-positive patient, CDC stage IIIB, who showed a clinically typical PAME.

RESULTS

While TCR-gamma gene rearrangement studies showed a polyclonal infiltrate confirming a pseudolymphoma, 85% of skin-infiltrating lymphocytes were CD8+ T cells.

CONCLUSION

PAME may also occur in HIV-positive patients with CD4+ deficiency. Our case demonstrates that regular CD4 counts and immunocompetence are not necessary for its pathogenesis.