The effects of miR-155/miR-21 on the expression of TLR4 in patients with acute Kawasaki disease

Abstract

Objective To investigate the effects of miR-155/miR-21 on the expression of TLR4 in patients with Kawasaki disease(KD). Methods Forty-five children with acute KD were enrolled into the study. Children were divided into the group with coronary artery lesions(KD-CAL+) and the group without coronary artery lesions(KD-CAL-). The age-matched twenty healthy children were included as the control group. The levels of TLR4 expression were analyzed by flow cytometry. The CD14+ monocytes in the peripheral blood were separated by CD14+ immunomagnetic beads. Real-time polymerase chain reaction(PCR) were performed to evaluate the expression of miR-155, miR-21 and interleukin(IL)-10, tumor necrosis factor(TNF)-α, IL-6, IL-1β in CD14+ monocytes at mRNA level. The concentration of matixmetalloproteinase(MMP)-9, HSP60, high mobility group box-1 protein(HMGB1) were measured by enzyme-linked immunosorbent assay(ELISA).T test was used to compare the differences between groups and P<0.05 was considered to be statistically significant. Results The levels of Toll-like receptor 4(TLR4) expression in children with acute KD were significantly higher than those in the control group [(12.4±5.1)% vs(4.6±1.6)%,t=5.55,P<0.05], and the levels of TLR4 expression in the KD-CAL+ group were remarkably elevated compared with the KD-CAL+ group [(17.1±4.6)% vs(9.6±2.7)%,t=5.89,P<0.05]. The plasma concentrations of HMGB11 [(10.2±7.6 vs 3.2±1.0) ng/ml,t =3.55,P<0.05] and HSP60[(56±23vs 18±7) ng/ml,t=4.90,P<0.05] in the KD group were increased(P<0.05), but significantly decreased after treatment with IVIG(P<0.05). The levels of miR-155[(21.0±27.0) ×10-3vs(4.6±3.1) ×10-3,t=2.57, P<0.05] and miR-21(11.6±4.0vs 8.7±2.2,t=2.78,P<0.05) expression in the KD group were significantly higher than those in the controls(P<0.05). The level of miR-155 expression in the KD-CAL+ group was apparently higher than that in the KD-CAL-group [(4.2±3.0)×10-2vs(11.0±1.5)×10-4,t=4.07,P<0.05] and the expression of miR-21 was lower than that in the KD-CAL-group(8.8±2.5 vs 12.8±4.0,t=3.46,P<0.05). Compared with the controls, the levels of IL-10 mRNA expression in the KD group were significantly increased [(34.9±17.5) × 10-4vs(1.0±9.4) × 10-4,t=5.62,P<0.05), and IL-10 expression in the KD-CAL-group was higher than that in the KD-CAL+ group [(26.6±13.4)×10-4vs(39.5±1.8)×10-4,t=2.36,P<0.05]. The plasma concentrations of MMP-9 in the KD group were remarkably higher than those in the controls [(1 141±541) pg/mlvs(304±94) pg/ml,t=4.83, P<0.05], the concentration of MMP-9 in the KD-CAL+ group was higher than that in the KD-CAL-group [(1 350±625) pg/ml vs(945±370) pg/ml,t=2.21,P<0.05]. Conclusion The dysregulation of miR-155 and miR-21 may be one of the reasons that result in over-expression of TLR4 in patients with acute KD, and the persistently increased HSP60 and HMGB1 may trigger or amplify TLR4 expression. Key words: Mucocutaneous lymph node syndrome; Toll-like receptor 4; Inflammatory cytokines; miR-155; miR-21