title: Whole blood-derived microRNA signatures in mice exposed to lipopolysaccharides.
abstract: BACKGROUND
  Lipopolysaccharide (LPS) is recognized as the most potent microbial mediator presaging the threat of invasion of Gram-negative bacteria that implicated in the pathogenesis of sepsis and septic shock. This study was designed to examine the microRNA (miRNA) expression in whole blood from mice injected with intraperitoneal LPS.
  
  
  METHODS
  C57BL/6 mice received intraperitoneal injections of varying concentrations (range, 10-1000 μg) of LPS from different bacteria, including Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Salmonella enterica, and Serratia marcescens and were killed 2, 6, 24, and 72 h after LPS injection. Whole blood samples were obtained and tissues, including lung, brain, liver, and spleen, were harvested for miRNA expression analysis using an miRNA array (Phalanx miRNA OneArray® 1.0). Upregulated expression of miRNA targets in the whole blood of C57BL/6 and Tlr4(-/-) mice injected with LPS was quantified using real-time RT-PCR and compared with that in the whole blood of C57BL/6 mice injected with lipoteichoic acid (LTA) from Staphylococcus aureus.
  
  
  RESULTS
  Following LPS injection, a significant increase of 15 miRNAs was observed in the whole blood. Among them, only 3 miRNAs showed up-regulated expression in the lung, but no miRNAs showed a high expression level in the other examined tissues. Upregulated expression of the miRNA targets (let-7d, miR-15b, miR-16, miR-25, miR-92a, miR-103, miR-107 and miR-451) following LPS injection on real-time RT-PCR was dose- and time-dependent. miRNA induction occurred after 2 h and persisted for at least 6 h. Exposure to LPS from different bacteria did not induce significantly different expression of these miRNA targets. Additionally, significantly lower expression levels of let-7d, miR-25, miR-92a, miR-103, and miR-107 were observed in whole blood of Tlr4(-/-) mice. In contrast, LTA exposure induced moderate expression of miR-451 but not of the other 7 miRNA targets.
  
  
  CONCLUSIONS
  We identified a specific whole blood-derived miRNA signature in mice exposed to LPS, but not to LTA, from different gram-negative bacteria. These whole blood-derived miRNAs are promising as biomarkers for LPS exposure.
authors: Department of Plastic and Reconstructive Surgery, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
authors: Ching-Hua
authors: CH
authors: Hsieh
authors: Cheng-Shyuan
authors: CS
authors: Rau
authors: Jonathan Chris
authors: JC
authors: Jeng
authors: Yi-Chun
authors: YC
authors: Chen
authors: Tsu-Hsiang
authors: TH
authors: Lu
authors: Chia-Jung
authors: CJ
authors: Wu
authors: Yi-Chan
authors: YC
authors: Wu
authors: Siou-Ling
authors: SL
authors: Tzeng
authors: Johnson Chia-Shen
authors: JC
authors: Yang
mesh_terms: D000818:Animals; D006090:Gram-Negative Bacteria / Q000737:chemistry; D007274:Injections, Intraperitoneal; D008070:Lipopolysaccharides / Q000008:administration & dosage* / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000097:blood* / Q000145:classification / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D013682:Teichoic Acids / Q000008:administration & dosage; D014018:Tissue Distribution; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome / Q000187:drug effects*
chemical_list: D008070:Lipopolysaccharides; D035683:MicroRNAs; D013682:Teichoic Acids; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; C009900:lipoteichoic acid