Assessment of HCMV-encoded microRNAs in plasma as potential biomarkers in pregnant women with adverse pregnancy outcomes

BACKGROUND: Human cytomegalovirus (HCMV) is the most frequent cause of congenital infections and can lead to adverse pregnancy outcomes (APOs). HCMV encodes multiple microRNAs (miRNAs) that have been reported to be partially related to host immune responses, cell cycle regulation, viral replication, and viral latency, and can be detected in human plasma. However, the relevance for HCMV-encoded miRNAs in maternal plasma as an indicator for APOs has never been evaluated. METHODS: Expression profiles of 22 HCMV-encoded miRNAs were first measured in plasma samples from 20 pregnant women with APOs and 28 normal controls using quantitative reverse-transcription polymerase chain reaction. Next, markedly changed miRNAs were validated in another independent validation set consisting of 20 pregnant women with APOs and 27 control subjects. Markedly changed miRNAs were further assessed in the placenta tissues. HCMV DNA in peripheral blood leukocytes (PBLs) and anti-HCMV immunoglobulin M (IgM) and anti-HCMV immunoglobulin G (IgG) in plasma were also examined in both training and validation sets. Diagnostic value and risk factors were compared between APO cohorts and normal controls. RESULTS: Analysis of the training and validation data sets revealed that plasma concentrations of hcmv-miR-UL148D, hcmv-miR-US25-1-5p and hcmv-miR-US5-1 were significantly increased in pregnant women with APOs compared with normal controls. Hcmv-miR-US25-1-5p presented the largest area under the receiver-operating characteristic (ROC) curve (AUC) (0.735; 95% CI, 0.635–0.836), with a sensitivity of 68% and specificity of 71%. Furthermore, plasma levels of hcmv-miR-US25-1-5p and hcmv-miR-US5-1 correlated positively with APOs (P=0.029 and 0.035, respectively). Hcmv-miR-US25-1-5p in the placenta tissues were dramatically increased in APOs, and correlated with plasma hcmv-miR-US25-1-5p. Nevertheless, neither the concentration of HCMV DNA in PBLs nor the positivity rates of anti-HCMV IgM and anti-HCMV IgG in plasma showed a statistically significant correlation with APOs. CONCLUSIONS: We identified a unique signature of HCMV-encoded miRNAs in pregnant women with APOs that may be useful as a potential noninvasive biomarker for predicting and monitoring APOs during HCMV infection.