Upregulation of miR-18a-5p contributes to epidermal necrolysis in severe drug eruptions.

BACKGROUND: Toxic epidermal necrolysis (TEN) is a severe drug-induced cutaneous reaction. Although one of the primary histologic features of TEN is keratinocyte apoptosis, its exact mechanism remains unknown. OBJECTIVES: We investigated the role of microRNAs (miRNAs) in the pathogenesis of severe drug eruptions and evaluated the possibility that miRNA can be a disease marker. METHODS: miRNAs were extracted from tissues and sera of patients. PCR array analyses were performed to identify pathogenic miRNAs. The results were confirmed with quantitative real-time PCR, in situ hybridization, transient transfection of small interfering RNAs or miRNA mimics into cultured keratinocytes, flow cytometry, immunoblotting, luciferase assay, and immunohistochemistry. RESULTS: PCR array analysis and real-time PCR using tissue miRNAs demonstrated that the miR-18a-5p level was increased in the skin of patients with TEN in vivo. Transfection of the miR-18a-5p mimic into keratinocytes in vitro resulted in increased apoptotic cell numbers and caspase-9 activity, which were also increased in the skin of patients with TEN. The miR-18a-5p mimic also downregulated the expression of B-cell lymphoma/leukemia-2-like protein 10 (BCL2L10), an anti-intrinsic apoptotic molecule. A luciferase assay with the BCL2L10 3' untranslated region showed BCL2L10 is directly targeted by miR-18a-5p. The protein and mRNA expressions of BCL2L10 were decreased in the skin of patients with TEN. Transfection with BCL2L10 small interfering RNA induced keratinocyte apoptosis and caspase activity. Furthermore, serum miR-18a-5p levels tended to be increased in patients with TEN and were correlated with areas of skin erythema or erosion in patients with drug eruptions. CONCLUSIONS: Our results indicated that downregulated BCL2L10 caused by miR-18a-5p overexpression mediates intrinsic keratinocyte apoptosis in patients with TEN. Serum miR-18a-5p levels can be a useful disease marker for drug eruptions.

Serum miR-124 up-regulation as a disease marker of toxic epidermal necrolysis.

BACKGROUND: Toxic epidermal necrolysis (TEN) is a lethal complication of drugs, thus early diagnosis and treatment are important. However, there are no satisfactory clinical biomarkers of TEN. OBJECTIVES: We investigated miR-124 and miR-214 expressions in serum and skin tissues of severe drug eruptions to evaluate the possibility of biomarkers of TEN. MATERIALS & METHODS: microRNAs were extracted from serum and skin tissues. Serum samples were obtained from 7 TEN patients, 5 Stevens-Johnson syndrome (SJS) patients, 11 erythema multiforme (EM) minor patients and 21 healthy volunteers. Skin tissues were obtained from 4 TEN patients, 3 SJS patients, 8 EM minor patients, 3 psoriasis and 3 atopic dermatitis patients. Six control skin samples were obtained. MicroRNA concentrations were determined by PCR array and real-time PCR. RESULTS: The concentrations of miR-124 in sera from TEN were significantly higher than those from healthy controls. In the characteristics curve analysis of serum miR-124 for differentiating TEN patients from normal subjects, the area under curve was 0.94. The serum miR-124 concentration was strongly correlated with the erosion area and the SCORTEN scale. The expression of miR-214 was significantly increased in the skin of TEN. CONCLUSION: The serum miR-124 concentration can be used as a disease activity marker for severe drug eruptions, reflecting the severity of keratinocyte apoptosis.