Shuen-Iu Hung

Granulysin is a key mediator for disseminated keratinocyte death in Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening adverse drug reactions characterized by massive epidermal necrosis, in which the specific danger signals involved remain unclear. Here we show that blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule, confirmed by quantitative PCR and immunohistochemistry. Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity. Granulysin in the blister fluids was a 15-kDa secretory form, and injection of it into mouse skin resulted in features mimicking SJS-TEN. Our findings demonstrate that secretory granulysin is a key molecule responsible for the disseminated keratinocyte death in SJS-TEN and highlight a mechanism for CTL- or NK cell—mediated cytotoxicity that does not require direct cellular contact.

Common risk allele in aromatic antiepileptic-drug induced Stevens-Johnson syndrome and toxic epidermal necrolysis in Han Chinese.

AIMS Compared with other categories of drugs, such as antibiotics and NSAIDs, antiepileptic therapies are associated with a high incidence of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We previously reported that carbamazepine (CBZ)-SJS/TEN is strongly associated with the HLA-B*1502 in Han Chinese, which has been confirmed in other Southeast Asian countries where the allele is prevalent. Here, we extend the study of HLA susceptibility to three different antiepileptic drugs, phenytoin (PHT), lamotrigine (LTG) and oxcarbazepine (OXC), which have structure similarity to CBZ. MATERIALS & METHODS We carried out a case-control association study. We enrolled 26 PHT-, six LTG- and three OXC-induced SJS/TEN patients, 113 PHT-tolerant and 67 LTG-tolerant subjects who were on the drug, respectively, for more than 3 months without the adverse reactions, and 93 normal subjects from the general population. The HLA-A, B, C and DRB1 genotypes were determined. RESULTS We found that HLA-B*1502 was present in eight out of 26 (30.8%) PHT-SJS/TEN (OR: 5.1; 95% CI: 1.8-15.1; p = 0.0041), two out of six (33%) LTG-SJS (odds ratio [OR]: 5.1; 95% CI: 0.8-33.8; p = 0.1266) and three out of three (100%) OXC-SJS (OR: 80.7; 95% CI: 3.8-1714.4; p = 8.4 x 10(-4)) patients. In addition, HLA-B*1301, Cw*0801 and DRB1*1602 also showed an association with PHT-SJS/TEN (p = 0.0128-0.0281; OR: 3.0-4.3). CONCLUSION Our results indicate that OXC, PHT and LTG, which possess an aromatic ring just as CBZ does, when causing SJS/TEN, share a common risk allele. Aromatic antiepileptic drugs causing SJS/TEN in HLA-B*1502 carriers may act on a similar pathogenetic mechanism, although other genetic/nongenetic factor(s) may also contribute to the pathomechanism of the disease. We suggest that aromatic antiepileptic drugs, including CBZ, OXC and PHT, should be avoided in the B*1502 carrier and caution should also be exercised for LTG.

Human leukocyte antigens and drug hypersensitivity

Purpose of reviewThe present article reviews the recent literature on the identification of human leukocyte antigen (HLA) alleles as major susceptible genes for drug hypersensitivity and discusses the clinical implications. Recent findingsSeveral recent studies have reported strong genetic associations between HLA alleles and susceptibility to drug hypersensitivity. The genetic associations can be drug specific, such as HLA-B*1502 being associated with carbamazepine-induced Stevens–Johnson syndrome and toxic epidermal necrolysis (SJS/TEN), HLA-B*5701 with abacavir hypersensitivity and HLA-B*5801 with allopurinol-induced severe cutaneous adverse reactions. A genetic association can also be phenotype-specific, as B*1502 is associated solely with carbamazepine-SJS/TEN, and not with either maculopapular eruption or hypersensitivity syndrome. Furthermore, a genetic association can also be ethnicity specific; carbamazepine-SJS/TEN associated with B*1502 is seen in south-east Asians but not in whites, which may be explained by the different allele frequencies. SummaryThe strong genetic association suggests a direct involvement of HLA in the pathogenesis of drug hypersensitivity when the HLA molecule presents an antigenic drug for T cell activation. The high sensitivity/specificity of some markers provides a plausible basis for developing tests to identify individuals at risk for drug hypersensitivity. Application of HLA-B*1502 genotyping as a screening tool before prescribing carbamazepine could be a valuable tool in preventing carbamazepine-induced SJS/TEN in south-east Asian countries.

Genetic Variants Associated With Phenytoin-Related Severe Cutaneous Adverse Reactions

IMPORTANCE The antiepileptic drug phenytoin can cause cutaneous adverse reactions, ranging from maculopapular exanthema to severe cutaneous adverse reactions, which include drug reactions with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, and toxic epidermal necrolysis. The pharmacogenomic basis of phenytoin-related severe cutaneous adverse reactions remains unknown. OBJECTIVE To investigate the genetic factors associated with phenytoin-related severe cutaneous adverse reactions. DESIGN, SETTING, AND PARTICIPANTS Case-control study conducted in 2002-2014 among 105 cases with phenytoin-related severe cutaneous adverse reactions (n=61 Stevens-Johnson syndrome/toxic epidermal necrolysis and n=44 drug reactions with eosinophilia and systemic symptoms), 78 cases with maculopapular exanthema, 130 phenytoin-tolerant control participants, and 3655 population controls from Taiwan, Japan, and Malaysia. A genome-wide association study (GWAS), direct sequencing of the associated loci, and replication analysis were conducted using the samples from Taiwan. The initial GWAS included samples of 60 cases with phenytoin-related severe cutaneous adverse reactions and 412 population controls from Taiwan. The results were validated in (1) 30 cases with severe cutaneous adverse reactions and 130 phenytoin-tolerant controls from Taiwan, (2) 9 patients with Stevens-Johnson syndrome/toxic epidermal necrolysis and 2869 population controls from Japan, and (3) 6 cases and 374 population controls from Malaysia. MAIN OUTCOMES AND MEASURES Specific genetic factors associated with phenytoin-related severe cutaneous adverse reactions. RESULTS The GWAS discovered a cluster of 16 single-nucleotide polymorphisms in CYP2C genes at 10q23.33 that reached genome-wide significance. Direct sequencing of CYP2C identified missense variant rs1057910 (CYP2C9*3) that showed significant association with phenytoin-related severe cutaneous adverse reactions (odds ratio, 12; 95% CI, 6.6-20; P=1.1 × 10(-17)). The statistically significant association between CYP2C9*3 and phenytoin-related severe cutaneous adverse reactions was observed in additional samples from Taiwan, Japan, and Malaysia. A meta-analysis using the data from the 3 populations showed an overall odds ratio of 11 (95% CI, 6.2-18; z=8.58; P < .00001) for CYP2C9*3 association with phenytoin-related severe cutaneous adverse reactions. Delayed clearance of plasma phenytoin was detected in patients with severe cutaneous adverse reactions, especially CYP2C9*3 carriers, providing a functional link of the associated variants to the disease. CONCLUSIONS AND RELEVANCE This study identified CYP2C variants, including CYP2C9*3, known to reduce drug clearance, as important genetic factors associated with phenytoin-related severe cutaneous adverse reactions.

Clinicopathlogical features and prognosis of drug rash with eosinophilia and systemic symptoms : a study of 30 cases in Taiwan

Background  Drug rash with eosinophilia and systemic symptoms (DRESS), a group of non‐blistering severe cutaneous adverse drug reactions (SCADRs), is characterized by skin rash and multiorgan involvement. Details of this reaction have not been reported in the literature so far.

HLA-A*31:01 and different types of carbamazepine-induced severe cutaneous adverse reactions: an international study and meta-analysis

HLA-A*31:01 was reported to be associated with carbamazepine (CBZ)-induced severe cutaneous adverse reactions (SCAR), including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We conducted an international study using consensus diagnosis criteria to enroll a total of 93 patients with CBZ-SCAR from Europe or Asia. We found that HLA-A*31:01 showed a significant association with CBZ-DRESS in Europeans (P<0.001; odds ratio (OR) (95% confidence interval (CI))=57.6 (11.0–340)), and the strong association was also found in Chinese (P<0.001; OR (95% CI)=23.0 (4.2–125)). However, HLA-A*31:01 had no association with CBZ-SJS/TEN in neither Chinese nor Europeans. By comparison, HLA-B*15:02 showed a strong association with CBZ-SJS/TEN in Chinese (P<0.001, OR (95% CI)=58.1 (17.6–192)). A meta-analysis of this and other published studies confirmed that in all populations, HLA-A*31:01 had an extremely strong association with CBZ-DRESS (P<0.001, a pooled OR (95% CI)=13.2 (8.4–20.8)), but a much weaker association with CBZ-SJS/TEN (P=0.01, OR (95% CI)=3.94 (1.4–11.5)). Our data revealed that HLA-A*31:01 is a specific predictor for CBZ-DRESS but not for CBZ-SJS/TEN. More studies are needed to investigate the genetic determinant of CBZ-SJS/TEN in Europeans. Considering the potential clinical utility, the cost-effectiveness of the combined HLA-A*31:01 and HLA-B*15:02 genetic test to prevent CBZ-SCAR in Chinese needs further investigation.

Insights into the poor prognosis of allopurinol-induced severe cutaneous adverse reactions: the impact of renal insufficiency, high plasma levels of oxypurinol and granulysin

Objective Allopurinol, an antihyperuricaemic agent, is one of the common causes of life-threatening severe cutaneous adverse reactions (SCAR), including drug rash with eosinophilia and systemic symptoms (DRESS), Stevens–Johnson syndrome (SJS) and toxic epidermal necrosis (TEN). The prognostic factors for allopurinol-related SCAR remain unclear. This study aimed to investigate the relationship of dosing, renal function, plasma levels of oxypurinol and granulysin (a cytotoxic protein of SJS/TEN), the disease severity and mortality in allopurinol-SCAR. Methods We prospectively enrolled 48 patients with allopurinol-SCAR (26 SJS/TEN and 22 DRESS) and 138 allopurinol-tolerant controls from 2007 to 2012. The human leucocyte antigen (HLA)-B*58:01 status, plasma concentrations of oxypurinol and granulysin were determined. Results In this cohort, HLA-B*58:01 was strongly associated with allopurinol-SCAR (p<0.001, OR (95% CI) 109 (25 to 481)); however, the initial/maintenance dosages showed no relationship with the disease. Poor renal function was significantly associated with the delayed clearance of plasma oxypurinol, and increased the risk of allopurinol-SCAR (p<0.001, OR (95% CI) 8.0 (3.9 to 17)). Sustained high levels of oxypurinol after allopurinol withdrawal correlated with the poor prognosis of allopurinol-SCAR. In particular, the increased plasma levels of oxypurinol and granulysin linked to the high mortality of allopurinol-SJS/TEN (p<0.01), and strongly associated with prolonged cutaneous reactions in allopurinol-DRESS (p<0.05). Conclusions Impaired renal function and increased plasma levels of oxypurinol and granulysin correlated with the poor prognosis of allopurinol-SCAR. Allopurinol prescription is suggested to be avoided in subjects with renal insufficiency and HLA-B*58:01 carriers. An early intervention to increase the clearance of plasma oxypurinol may improve the prognosis of allopurinol-SCAR.

Transient expression of Ym1, a heparin-binding lectin, during developmental hematopoiesis and inflammation.

Ym1, a secretory protein transiently produced by activated peritoneal macrophages elicited by parasitic infections, has been identified as a novel heparin‐binding lectin. X‐ray crystallography study revealed that Ym1 has a β/α barrel structure with a carbohydrate‐binding cleft similar to that of triose‐phosphate isomerases. To further delineate the physiological significance of Ym1, we examined its expression patterns during mouse embryonic development and inflammation states elicited by agents other than parasitic infections in the peritoneal cavity and brain. This is the first report revealing prominent expression of Ym1 in early myeloid precursor cells of hematopoietic tissues—initially in the yolk sac and subsequently in fetal liver, spleen, and bone marrow. In nonhematopoietic systems, Ym1 was not detected in most of the tissues examined, with the exception of lung. Although no expression was detected up to gestation day 16.5 (E16.5), an increasing level of Ym1 expression in lung was detected from E18.5 on and persisted through adulthood. While most resident macrophages in various tissues examined are Ym1‐negative, transient expression of Ym1 may be induced in their activated counterparts during inflammation in response to different stimuli in vivo, ranging from various chemical agents to brain injuries. The temporal and spatial expression in myeloid precursors and its transient induction in activated macrophages support the notion that Ym1 may be involved in hematopoiesis and inflammation. In addition, its putative functional association with heparin/heparan sulfate is discussed.

Evolving models of the immunopathogenesis of T cell–mediated drug allergy: The role of host, pathogens, and drug response

Immune-mediated (IM) adverse drug reactions (ADRs) are an underrecognized source of preventable morbidity, mortality, and cost. Increasingly, genetic variation in the HLA loci is associated with risk of severe reactions, highlighting the importance of T-cell immune responses in the mechanisms of both B cell-mediated and primary T cell-mediated IM-ADRs. In this review we summarize the role of host genetics, microbes, and drugs in IM-ADR development; expand on the existing models of IM-ADR pathogenesis to address multiple unexplained observations; discuss the implications of this work in clinical practice today; and describe future applications for preclinical drug toxicity screening, drug design, and development.

A single nucleotide polymorphism fine mapping study of chromosome 1q42.1 reveals the vulnerability genes for schizophrenia, GNPAT and DISC1 : Association with impairment of sustained attention

BACKGROUND The marker D1S251 of chromosome 1q42.1 showed significant association with schizophrenia in a Taiwanese sample. We used single nucleotide polymorphism (SNP) fine mapping to search for the vulnerability genes of schizophrenia. METHODS We selected 120 SNPs covering 1 Mb around D1S251 from the public database. These selected SNPs were initially validated if allele frequency was >10%. Forty-seven validated SNPs were genotyped in 102 families with at least 2 siblings affected with schizophrenia. RESULTS Two SNP blocks showed significant association with schizophrenia. Block 1 (five-SNP), located between intron 2 and intron 13 of the glyceronephosphate O-acyltransferase (GNPAT) gene, showed the most significant associations using single-locus TDT (z = -2.07, p = .038, df = 1) and haplotype association analyses (z = -1.99, p = .046, df = 1). Block 2 (two-SNP), located between intron 4 and intron 5 of the disrupted-in-schizophrenia 1 (DISC1) gene, also showed the most significant results in both the single-locus (z = -3.22, p = .0013, df = 1) and haplotype association analyses (z = 3.35, p = .0008, df = 1). The association of the DISC1 gene with schizophrenia was mainly in the patient group with sustained attention deficits as assessed by the Continuous Performance Test. CONCLUSIONS Chromosome 1q42.1 harbors GNPAT and DISC1 as candidate genes for schizophrenia, and DISC1 is associated with sustained attention deficits.