Is HERV-K and HERV-W Expression Regulated by miR-155 in Kidney Transplant Patients with Human Cytomegalovirus Infection?

According to the latest update, 2,578 unique mature micro­RNAs (miRNAs) are currently annotated in the human genome and participate in the regulation of multiple events, such as cellular proliferation or apoptosis. A previous study analyzing global miRNA expression patterns in GH cells (high human endogenous retrovirus, HERV, K vs. low) showed that 2 miRNAs (miR-663 and miR-638) are differentially regulated and exhibit expression parallel to that of HERV-K. The aim of this study was to evaluate HERV-K and -W pol gene and miR-155 expression in kidney transplant recipients and the possible relationship between them. The comparison between kidney transplant patients negative for human cytomegalovirus (HCMV) infection and positive patients showed a significant difference in terms of miR-155 expression (p = 0.0111). We demonstrated that HERV-K and -W pol gene expression was significantly higher in CMV-infected kidney transplant recipients versus those not infected as previously reported by our groups. Our correlation data suggest that miR-155 are not directly involved in regulating the HERV notwithstanding that we together observed increased expression of HERV-K and -W and diminished expression of miR-155 in HCMV-infected human kidney transplant recipients.