The level of microRNA expression in cardiac surgery patients depends on postoperative multiorgan failure

Aim: To assess the level of microRNA expression in the serum of patients who had undergone cardiac surgery depending on the postoperative complications (presence or absence of multiorgan failure, MOF). Materials and methods: The study group included 87 patients who had undergone heart surgery with cardiopulmonary bypass. The patients without postoperative complications comprised group 1 (n = 51), whereas those with postoperative MOF were in group 2 (n = 36). In all patients, blood samples were collected at two time points: before surgery and at 36 to 48 hours after surgery. The following miRNAs were chosen for the study: hsa-miR-486-5p (478128_miR), hsa-miR-191-5p (477952_miR), hsa-miR-192-5p (478262_miR), hsa-miR-146a-5p (478399_miR), hsa-miR-26a-5p (477995_miR), hsa-miR-30d-5p (478606_miR), hsa-miR-23a-3p (478532_miR), and hsa-miR-320a-5p (481049_miR). Polymerase chain reaction results were normalized to hsa-miR-16-5p (4427975). Results: Up-regulating miRNAs. Compared to baseline, there was a significant postoperative increase in miR-486-5p microRNA expression (group 1, 41.83 [19.86; 74.6] vs 940 [434.7; 1212.0]; group 2, 72.55 [21.37; 100.2] vs 492.4 [201.2; 998.0]; both p 0.001). An increase in the of microRNA miR-192-5p expression in the postoperative period was found both in the no-MOF group (from 0.39 [0.16; 1.07] at baseline to 5.96 [3.74; 10.35] after surgery, p = 0.002), and in the MOF group (from 1.74 [0.45; 3.35] at baseline to 17.16 [4.70; 24.96] after surgery, p = 0.003), with a statistically higher level of expression in group 2 (p = 0.028). Similar changes over time were observed for miR-30d-5p expression: group 1, 1.61 [0.47; 4.36] at baseline vs 5.03 [2.93; 6.56] after surgery (p = 0.002), group 2, 0.89 [0.32; 4.27] at baseline and 6.63 [3.92; 12.82] after surgery, respectively (p = 0.0045). Down-regulating miRNAs. The miR-191-5 and miR-146a-5p families demonstrated a significant increase in group 1 after surgery (3.85 [1.64; 5.6] vs 7.7 [5.48; 9.68], p = 0.021; and 18.1 [6.52; 19.9] vs 37.27 [29.13; 47.07], p = 0.016, respectively) and a significant postoperative decrease in group 2 (3.67 [2.60; 7.61] vs 1.66 [0.52; 2.36], p = 0.023; and 14.75 [12.79; 21.77] vs 5.96 [2.8; 8.2], p = 0.034, respectively), with between-group difference in the postoperative expression levels being also significant. As regards to miR-26a-5p и miR-23a-3p families, there was a similar trend: the group with uncomplicated postoperative course was had virtually no changes over time in their expression (the increase was non-significant), whereas the MOF group had lower postoperative values for this microRNA family. The between-group differences after surgery were significant for miR-26a-5p (group 1, 6.79 [3.38; 8.46], group 2, 0.26 [0.18; 1.9], p = 0.037) and for miR-23a-3p (14.14 [11.92; 26.63] and 2.0 [1.02; 4.18], respectively, p 0.001). Conclusion: When comparing microRNA expression before surgery, we did not find any significant differences between the patients groups without and with MOF. Assessment of microRNA expression in the no-MOF group after surgery showed an increase in the expression of microRNAs responsible both for up regulation (miR-486-5p, miR-192-5p, miR-30d-5p) and for down regulation (miR-191-5p, miR-146a-5p). In the group with a complicated postoperative course and with MOF, changes over time in the up-regulating microRNAs were characterized by increased expression (miR-486-5p, miR-192-5p, miR-30d-5p), whereas the down-regulating microRNAs (miR-191-5p, miR-146a-5p) demonstrated significantly decreased expression, which was different both that in the no-MOF group and from the baseline values.