The MiRNA Expression Profiles And Immune Regulation Functions In Neonatal Sepsis

Part 1. Altered miRNAs expression profiles and modulation of immune response genes and proteins during neonatal sepsisObjective The dysregulated expression of miRNAs in the immune system may be critical for immune responses to pathogens and evolve into the inflammation seen in sepsis. The aim of this study is to explore the important role of miRNAs in the regulation of the immune response during neonatal sepsis.Methods Using a microarray we performed the miRNA expression profiling of peripheral blood leukocytes from neonates with sepsis and uninfected neonates. Based on the predicted target genes of these miRNAs we selected 26 immune-related miRNAs out of the differentially expressed miRNAs for further testing by quantitative PCR. We simultaneously detected the immune response genes by PCRî–˜ array and plasma cytokine levels using a protein chip to investigate the effect of the altered miRNAs on the immune response in neonatal sepsis.Results There were 10 immune regulatory miRNAs whose expression was significantly changed more than two fold in the neonates with sepsis compared with the uninfected neonates. The expression levels of 11 immune response genes and the plasma levels of 15 cytokines or receptors were significantly up- or down-regulated in the neonates with sepsis compared to the uninfected neonates. This comprehensive analysis suggests that the altered miRNAs modulate the immune response during neonatal sepsis in a way that represses the inflammatory response.Conclusions Our investigation demonstrated some miRNAs with altered expression levels and their probable association with the regulation of immune response during neonatal sepsis. The characteristics of the neonatal inflammatory response could be attributed to immature immune function of neonates.Part 2. LPS-induced miRNAs expression profiles and modulation of TLR signaling pathway genes in cord blood leukocytes and the differences between newborns and adultsObjective In order to further confirm the role of miRNAs in the regulation of neonatal anti-infection immunity and inflammation, we performed an in vitro study. In this study, LPS-induced miRNAs expression profiles and modulation of TLR signaling pathway genes in cord blood leukocytes (CBL) and the differences between newborns and adults were explored.Methods The expression profiles of LPS-induced miRNAs and TLR-related genes were studied by microarray and PCR arrays, respectively. A bioinformatics analysis was used to identify the potential biological processes and targets involved in the TLR signals affected by these miRNAs.Results A total of 85 miRNAs and 41 TLR-related genes were differentially expressed between LPS-stimulated and LPS-unstimulated CBL. Between LPS-stimulated CBL and LPS-stimulated adult peripheral blood leukocytes (APBL) 53 miRNAs and 29 TLR-related genes were found differentially expressed. The bioinformatics analysis showed that the potential target genes of LPS-induced miRNAs in CBL were involved in regulation of cellular biosynthetic process, regulation of gene expression, regulation of macromolecule biosynthetic process, etc, no matter up- or down regulation. However, the potential target genes of the differential expressed miRNAs emerged between LPS-stimulated CBL and LPS-stimulated APBL made a difference in cellular protein metabolic process, negative regulation macromolecule metabolic process, etc. Thirteen potential miRNA-mRNA interaction sites were found within the cDNA sequences of eleven differentially expressed TLR signaling pathway genes in LPS-stimulated CBL. Ten differentially expressed TLR signaling pathway genes tended to be regulated by twelve differentially expressed miRNAs between LPS-stimulated CBL and LPS-stimulated APBL.Conclusions We identified a global miRNA expression signature occurring during LPS-induced acute inflammation in CBL, and the differences between CBL and APBL. The target genes of these altered miRNAs were mainly involved in several biological processes, and these miRNAs may play important roles in the regulation of TLR signals. In addition, this kind of regulation is different between newborns and adults.