Influence of microRNA-155 and microRNA-21 on expression of Toll-like receptor 4 in children with sepsis

Abstract

Objective To discuss the influence of microRNA(miR)-155/miR-21 on toll-like receptor 4 (TLR4) in children with sepsis. Methods Fifty children with sepsis who were hospita-lized in Pediatric Intensive Care Unit, Shenzhen Children′s Hospital, were enrolled in the study, and 15 healthy children at the same age were selected as healthy control group.Expression levels of TLR4 protein and human leukocyte antigen(HLA)-DR in CD14＋ monocytes (MC) were detected by using flow cytometry, and sepsis patients were divided into 2 groups according to whether they exceeded the value of HLA-DR by 30% or not.Expression level of programmed cell death factor 4 (PDCD4) and inositol phosphatases 1 containing SH2 (SHIP1) were detected at the same time.MC were separated by CD14＋ immune magnetic bead, and expression level of miR-155, miR-21 and tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) mRNA in CD14＋ MC were detected by using real-time fluorescent quantitative PCR. Results Sepsis group consisted of 27 male and 23 female, and their ages were (2.34±0.79) years old, among whom 9 patients died.There were 36 patients in the HLA-DR increase group and 14 patients in the HLA-DR decrease group.Expressions of TLR4(2.33±0.90), miR-155[(7.19±3.75)×10-3] and TNF-α[(21.98±14.15)×10-2 μg/L] in CD14＋ MC were higher in the HLA-DR increase group than those in the HLA-DR decrease group[1.24±0.60, (4.83±1.17) ×10-3, (14.18±5.45)×10-2 μg/L] and healthy control group[1.57±0.55, (3.99±1.29)×10-3, (1.61±0.84)×10-2 μg/L], and the differences were statistically significant(F=11.943, 7.583, 18.538, all P<0.05), while the expressions of miR-21(12.10±5.66), IL-10[(29.74±12.55)×10-4 μg/L] in CD14＋ MC were lower in the HLA-DR increase group than those in the HLA-DR decrease group[4.68±2.07, (12.50±5.73)×10-4 μg/L] and healthy control group [2.39±0.86, (2.04±0.92)×10-4 μg/L], and the differences were statistically significant(F=41.673, 54.991, all P<0.05). The levels of SHIP1 and PDCD4 decreased in sepsis compared with healthy control group[0.70±0.36)vs.(1.59±0.48); (1.55±0.56) vs.(3.01±0.70)], and the differences were statistically significant (t=7.682, 8.339, all P<0.05), but SHIP1 decreased more significantly in the HLA-DR increase group than that in the HLA-DR decrease group[(0.60±0.34) vs.(0.97±0.26)], and the difference was statistically significant(F=39.214, P<0.05). PDCD4 decreased more significantly in the HLA-DR decrease group than that in the HLA-DR increase group (0.94±0.19 vs.1.79±0.47), the difference was statistically significant(F=65.367, P<0.05). Conclusions Regulation imbalance of miR-155/miR-21 may be one of the reasons for abnormal expression of TLR4 in children with sepsis, and it plays a role in enlarged or inhibited expression of TLR4 in the sepsis process which results in different immune status in sepsis patients. Key words: Child; microRNA-155; microRNA-21; Sepsis; Monocytes