Mir-155 expression is downregulated in hematopoietic stem cell transplantation patients with Epstein-Barr virus infection.

Abstract

MicroRNAs (miRNAs) are a class of short length double strand genome encoded RNAs that are produced to repress post-transcriptionally the expression of cellular mRNAs. 2578 unique mature miRNAs are currently annotated in the human genome and participate in the regulation of multiple events, such as cellular proliferation or apoptosis. The over-expression of miR-155 of cellular origin might play a key role in the life cycle of EBV. In this study 24 pediatric patients undergoing HSCT seropositive and seronegative to EBV were enrolled. Thirty-one peripheral blood samples were collected from these patients. The mir-155 expression profile has been evaluated by a stem-loop Real Time PCR in all these conditions. Of 24 patients, 4 were seronegative to EBV and EBV negative to PCR (Group I), 10 were seropositive to EBV and EBV negative to PCR (Group II) and 10 were seropositive to EBV and EBV positive to PCR (Group III). Based on relative quantification, the mir-155 expression was compared among the groups. The comparison between HSCT patients without EBV infection seronegative to EBV (Group I) showed higher levels of mir-155 expression than patients seropositive to EBV (P=0.1419). The mir-155 expression levels in seronegative to EBV were not significantly different compared with the patients seropositive to EBV (P=0.6504). The mir-155 expression levels in seropositive to EBV without and with EBV infection (positive viral load), were not significantly (P=0.7667). Also, when we evaluated the mir-155 expression levels comparing all EBV negative patients with an active EBV infection, we did not observe a statistically significant difference (P=0.9782). Our results are controversial, showing a higher production of mir-155 levels during EBV infection.