LAUSR

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS) is a life-threatening multi-organ hypersensitivity reaction. Reactivation of human herpesvirus 6B (HHV-6B), which typically occurs 2–3 weeks after its onset, has been implicated in DIHS/DRESS (1). Reactivation of HHV-6 has been reported to correlate with flaring of symptoms such as fever and hepatitis (2) and renal failure (3) in patients with DIHS/DRESS, indicating that virus reactivation could contribute to some symptoms or complications in DIHS/DRESS. However, it has also been reported that reactivation of HHV-6 could be merely a result of a strong drug-specific immune response and not contribute to DRESS symptoms and severity (4). MicroRNAs (miRNAs) play important roles in biological processes such as immune responses and cell differentiation. Herpesviruses express their own miRNAs and may regulate key viral genes (5). HHV-6A encodes miR-U86 that regulates viral lytic replication (6), while HHV-6B encodes at least 4 miRNAs: hhv6b-miR-Ro6-1, -2, -3 and -4 (7). However, the precise roles of these 4 miRNAs in the regulation of HHV-6B latency and reactivation remain largely unknown. Moreover, the roles of individual miRNAs in DIHS/DRESS have not yet been elucidated. The present study investigated the expression levels of the 4 HHV-6B miRNAs in the serum of patients with DIHS/DRESS during the acute and subacute stages.