Exosomal microRNAs from PBMCs stimulated with culprit drugs enhanced keratinocyte cell death in Stevens-Johnson syndrome/toxic epidermal necrolysis.

BACKGROUND: Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) and drug reactions with eosinophilia and systemic symptoms (DRESS) are both severe cutaneous adverse reactions. Keratinocyte death is much more prominent in SJS/TEN compared to DRESS. OBJECTIVE: This study aimed to investigate the role of exosomal miRNAs on keratinocyte death in SJS/TEN. METHODS: Peripheral blood mononuclear cells (PBMCs) from SJS/TEN and DRESS patients were stimulated with the culprit drugs. The exosomes released in cell supernatants were co-incubated with HaCaT cells to study the cytotoxic effects on keratinocytes. Exosomal miRNA sequencing analysis was performed to compare the expression patterns between SJS/TEN and DRESS subjects. HaCaT cells were then transfected with miRNA mimics and inhibitors to explore the functions of miRNAs on keratinocyte cell death. RESULTS: Cytotoxic effects of PBMC-derived exosomes on keratinocytes were demonstrated in SJS/TEN and could be neutralized with exosome inhibitors. Cytotoxic effects of PBMC-derived exosomes from SJS/TEN subjects were higher after incubating PBMCs with the culprit drugs than those incubating with irrelevant drugs and unstimulated controls. The sequencing data revealed differential expressions of 61 exosomal miRNAs between SJS/TEN and DRESS. Exosomal miR-4488 was upregulated while miR-486-5p, miR-96-5p and miR-132-3p were downregulated in SJS/TEN compared to DRESS as determined by quantitative real-time PCR. The increased percentage of apoptotic cells upon transfection of HaCat cells was 36.3% and 34.9% with miR-4488 mimic and miR-96-5p inhibitor, respectively. CONCLUSION: This study illustrated the regulatory functions of exosomal miRNAs in controlling keratinocyte death in SJS/TEN. Exosome inhibitors might have a therapeutic role in SJS/TEN.

Analysis of HLA-B Allelic Variation and IFN-γ ELISpot Responses in Patients with Severe Cutaneous Adverse Reactions Associated with Drugs.

BACKGROUND: The prevention and confirmation of drug-induced severe cutaneous adverse reactions (SCARs) are difficult. OBJECTIVE: To determine the benefit of HLA-B allele prescreening and the measurement of drug-specific IFN-γ-releasing cells in the prevention and identification of the culprit drug in patients with SCARs. METHODS: A total of 160 patients with SCARs were recruited from 6 university hospitals in Thailand over a 3-year period. HLA-B alleles were genotypically analyzed. The frequencies of drug-specific IFN-γ-releasing cells in patients with SCARs were also measured. RESULTS: The drugs commonly responsible for SCARs were anticonvulsants, allopurinol, beta-lactams, antituberculosis agents, and sulfonamides. If culprit drugs had been withheld in patients carrying known HLA-B alleles at risk, it would have prevented 21.2% of SCAR cases, mainly allopurinol- and carbamazepine-related SCARs. Culprit drug-specific IFN-γ-releasing cells could be identified in 45.7% (53 of 116) of patients with SCARs caused by 5 major drug groups, particularly in patients diagnosed with drug reactions with eosinophilia and systemic symptoms (DRESS) (50.0%), followed by Stevens-Johnson syndrome/toxic epidermal necrolysis (46.0%), and acute generalized exanthematous pustulosis (31.3%). According to our study, high frequencies of drug-specific IFN-γ-releasing cells were significantly demonstrated in patients who suffered from DRESS phenotype, having anticonvulsants or the drugs belonging to the "probable" category based on the Naranjo algorithm scale, as the culprit drugs. CONCLUSIONS: HLA-B prescreening would succeed in preventing only a minority of SCAR victims. Drug-specific IFN-γ-releasing cells are detectable in almost half of patients. Better strategies are required for better SCAR prevention and culprit drug confirmation.