Siou-Ling Tzeng

Whole blood-derived microRNA signatures in mice exposed to lipopolysaccharides

BackgroundLipopolysaccharide (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.MethodsC57BL/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.ResultsFollowing 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.ConclusionsWe 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.

Profiling Circulating MicroRNA Expression in Experimental Sepsis Using Cecal Ligation and Puncture

The levels of circulating microRNAs (miRNAs) in mice with experimental sepsis induced by cecal ligation and puncture (CLP) were determined using whole blood samples obtained from C57BL/6 mice at 4, 8, and 24 h after CLP; miRNA expression analysis was performed in these samples using an miRNA array. Microarray analysis revealed upregulation of 10 miRNA targets (miR-16, miR-17, miR-20a, miR-20b, miR-26a, miR-26b, miR-106a, miR-106b, miR-195, and miR-451). The expression of these miRNA targets in the whole blood, serum, and white blood cells (WBCs) of CLP mice was quantified using quantitative real-time PCR; these values were compared to those in sham-operated C57BL/6 mice, and the results indicated that these miRNA targets were significantly up-regulated in the whole blood and serum but not in the WBCs. In addition, the levels of these 10 miRNA targets in the serum of Tlr2−/−, Tlr4−/−, and NF-κB−/− mice at 8 h after CLP did not decrease significantly., which indicated that the transcription of these miRNAs was not directly mediated by the TLR2/NF-κB or TLR4/NF-κB pathway, and pathways induced by exposure to the gram-positive or gram-negative bacteria. Immunoprecipitation with the Argonaute 2 ribonucleoprotein complex revealed significantly increased expression of the 10 miRNA targets in the serum of mice after CLP, and the levels of 6 (miR-16, miR-17, miR-20a, miR-20b, miR-26a, and miR-26b) of these 10 miRNA targets increased significantly in exosomes isolated using ExoQuick precipitation solution. In this study, we identified circulating miRNAs that were up-regulated after CLP and determined the increase in the levels of these miRNAs, and our results suggest that circulating Ago2 complexes and exosomes may be responsible for the stability of miRNAs in the serum.

Circulating microRNA signatures in mice exposed to lipoteichoic acid

BackgroundPreviously, we had identified a specific whole blood–derived microRNAs (miRNAs) signature in mice following in vivo injection of lipopolysaccharide (LPS) originated from Gram-negative bacteria. This study was designed to profile the circulating miRNAs expression in mice exposed to lipoteichoic acid (LTA) which is a major component of the wall of Gram-positive bacteria.ResultsC57BL/6 mice received intraperitoneal injections of 100 μg of LTA originated from Bacillus subtilis, Streptococcus faecalis, and Staphylococcus aureus were killed 6 h and the whole blood samples were obtained for miRNA expression analysis using a miRNA array (Phalanx miRNA OneArray® 1.0). Up-regulated expression of miRNA targets in the whole blood, serum and white blood cells (WBCs) of C57BL/6 and Tlr2−/− mice upon LTA treatment in 10, 100, or 1000 ug concentrations was quantified at indicated time (2, 6, 24, and 72 h) using real-time RT-PCR and compared with that in the serum of C57BL/6 mice injected with 100 ug of LPS. A significant increase of 4 miRNAs (miR-451, miR-668, miR-1902, and miR-1904) was observed in the whole blood and the serum in a dose- and time-dependent fashion following LTA injection. Induction of miRNA occurred in the serum after 2 h and persisted for at least 6 h. No increased expression of these 4 miRNAs was found in the WBCs. Higher but not significant expression level of these 4 miRNAs were observed following LTA treatment in the serum of Tlr2−/−against that of C57BL6 mice. In contrast, LPS exposure induced moderate expression of miR-451 but not of the other 3 miRNA targets.ConclusionsWe identified a specific circulating miRNA signature in mice exposed to LTA. That expression profile is different from those of mice exposed to LPS. Those circulating miRNAs induced by LTA or LPS treatment may serve as promising biomarkers for the differentiation between exposures to Gram-positive or Gram-negative bacteria.

Weight-reduction through a low-fat diet causes differential expression of circulating microRNAs in obese C57BL/6 mice

BackgroundTo examine the circulating microRNA (miRNA) expression profile in a mouse model of diet-induced obesity (DIO) with subsequent weight reduction achieved via low-fat diet (LFD) feeding.ResultsEighteen C57BL/6NCrl male mice were divided into three subgroups: (1) control, mice were fed a standard AIN-76A (fat: 11.5 kcal %) diet for 12 weeks; (2) DIO, mice were fed a 58 kcal % high-fat diet (HFD) for 12 weeks; and (3) DIO + LFD, mice were fed a HFD for 8 weeks to induce obesity and then switched to a 10.5 kcal % LFD for 4 weeks. A switch to LFD feeding led to decreases in body weight, adiposity, and blood glucose levels in DIO mice. Microarray analysis of miRNA using The Mouse & Rat miRNA OneArray® v4 system revealed significant alterations in the expression of miRNAs in DIO and DIO + LFD mice. Notably, 23 circulating miRNAs (mmu-miR-16, mmu-let-7i, mmu-miR-26a, mmu-miR-17, mmu-miR-107, mmu-miR-195, mmu-miR-20a, mmu-miR-25, mmu-miR-15b, mmu-miR-15a, mmu-let-7b, mmu-let-7a, mmu-let-7c, mmu-miR-103, mmu-let-7f, mmu-miR-106a, mmu-miR-106b, mmu-miR-93, mmu-miR-23b, mmu-miR-21, mmu-miR-30b, mmu-miR-221, and mmu-miR-19b) were significantly downregulated in DIO mice but upregulated in DIO + LFD mice. Target prediction and function annotation of associated genes revealed that these genes were predominantly involved in metabolic, insulin signaling, and adipocytokine signaling pathways that directly link the pathophysiological changes associated with obesity and weight reduction.ConclusionsThese results imply that obesity-related reductions in the expression of circulating miRNAs could be reversed through changes in metabolism associated with weight reduction achieved through LFD feeding.

Lipopolysaccharide-induced microRNA-146a targets CARD10 and regulates angiogenesis in human umbilical vein endothelial cells.

This aim of this study was to explore the role of miRNA-146a (miR-146a) and its target genes in endothelial cells. We demonstrated that lipopolysaccharide (LPS) induced the upregulation of miR-146a in human umbilical vein endothelial cells (HUVECs), and that the induction was blocked by silencing toll-like receptors, the adaptor molecule MyD88, and the nonspecific NF-κB inhibitor BAY 11-7082. In addition, knockdown of miR-146a by transfection of the locked nucleic acid antimiR-146a significantly inhibited LPS-induced cell migration and tube formation. A combined analysis of bioinformatics miRanda algorithms and a whole genome expression microarray of immunoprecipitated Ago2 ribonucleoprotein complexes identified 14 potential target genes. Subsequent transfection with the miR-146a precursor pre-miR-146a into HUVECs validated that CARD10 was the target gene of the miR-146a, both at the mRNA and protein levels. Silencing CARD10 inhibited p65 nuclear translocation in the cells receiving LPS stimulation and increased angiogenesis. Therefore, miR-146a may play a role in regulating the angiogenesis in HUVECs by downregulating CARD10, which acts in a negative feedback regulation loop to inhibit the activation of NF-κB that normally impairs angiogenesis.

Altered exosomal protein expression in the serum of NF-κB knockout mice following skeletal muscle ischemia-reperfusion injury

BackgroundThe NF-κB signaling pathway plays a role in local and remote tissue damage following ischemia-reperfusion (I/R) injury to skeletal muscles. Evidence suggests that exosomes can act as intercellular communicators by transporting active proteins to remote cells and may play a role in regulating inflammatory processes. This study aimed to profile the exosomal protein expression in the serum of NF-κB knockout mice following skeletal muscle ischemia-reperfusion injury.ResultsTo investigate the potential changes in protein expression mediated by NF-κB in secreted exosomes in the serum following I/R injury, the levels of circulating exosomal proteomes in C57BL/6 and NF-κB−/− mice were compared using two dimensional differential in-gel electrophoresis (2-DE), liquid chromatography tandem mass spectrometry (LC-MS/MS), and proteomic analysis. In C57BL/6 mice, the levels of circulating exosomal proteins, including complement component C3 prepropeptide, PK-120 precursor, alpha-amylase one precursor, beta-enolase isoform 1, and adenylosuccinate synthetase isozyme 1, increased following I/R injury. However, in the NF-κB−/− mice, the expression of the following was upregulated in the exosomes: protease, serine 1; glyceraldehyde-3-phosphate dehydrogenase-like isoform 1; glyceraldehyde-3-phosphate dehydrogenase; and pregnancy zone protein. In contrast, the expression of apolipoprotein B, complement component C3 prepropeptide, and immunoglobulin kappa light chain variable region was downregulated in NF-κB−/− mice. Bioinformatic annotation using the Protein Analysis Through Evolutionary Relationships (PANTHER) database revealed that the expression of the exosomal proteins that participate in metabolic processes and in biological regulation was lower in NF-κB−/− mice than in C57BL/6 mice, whereas the expression of proteins that participate in the response to stimuli, in cellular processes, and in the immune system was higher.ConclusionsThe data presented in this study suggest that NF-κB might regulate exosomal protein expression at a remote site via circulation following I/R injury.

Profiling circulating microRNA expression in a mouse model of nerve allotransplantation

BackgroundThe lack of noninvasive biomarkers of rejection remains a challenge in the accurate monitoring of deeply buried nerve allografts and precludes optimization of therapeutic intervention. This study aimed to establish the expression profile of circulating microRNAs (miRNAs) during nerve allotransplantation with or without immunosuppression.ResultsBalb/c mice were randomized into 3 experimental groups, that is, (1) untreated isograft (Balb/c → Balb/c), (2) untreated allograft (C57BL/6 → Balb/c), and (3) allograft (C57BL/6 → Balb/c) with FK506 immunosuppression. A 1-cm Balb/c or C57BL/6 donor sciatic nerve graft was transplanted into sciatic nerve gaps created in recipient mice. At 1, 3, 7, 10, and 14 d after nerve transplantation, nerve grafts, whole blood, and sera were obtained for miRNA expression analysis with an miRNA array and subsequent validation with quantitative real-time PCR (qRT-PCR). Three circulating miRNAs (miR-320, miR-762, and miR-423-5p) were identified in the whole blood and serum of the mice receiving an allograft with FK506 immunosuppression, within 2 weeks after nerve allotransplantation. However, these 3 circulating miRNAs were not expressed in the nerve grafts. The expression of all these 3 upregulated circulating miRNAs significantly decreased at 2, 4, and 6 d after discontinuation of FK506 immunosuppression. In the nerve graft, miR-125-3b and miR-672 were significantly upregulated in the mice that received an allograft with FK506 only at 7 d after nerve allotransplantation.ConclusionsWe identified the circulating miR-320, miR-762, and miR-423-5p as potential biomarkers for monitoring the immunosuppression status of the nerve allograft. However, further research is required to investigate the mechanism behind the dysregulation of these markers and to evaluate their prognostic value in nerve allotransplantation.

TLR4/NF-κB-Responsive MicroRNAs and Their Potential Target Genes: A Mouse Model of Skeletal Muscle Ischemia-Reperfusion Injury

Background. The aim of this study was to profile TLR4/NF-κB-responsive microRNAs (miRNAs) and their potential target genes in the skeletal muscles of mice following ischemia-reperfusion injury. Methods. Thigh skeletal muscles of C57BL/6, Tlr4 −/−, and NF-κB −/− mice isolated based on femoral artery perfusion were subjected to ischemia for 2 h and reperfusion for 0 h, 4 h, 1 d, and 7 d. The muscle specimens were analyzed with miRNA arrays. Immunoprecipitation with an argonaute 2- (Ago2-) specific monoclonal antibody followed by whole genome microarray was performed to identify mRNA associated with the RNA-silencing machinery. The potential targets of each upregulated miRNA were identified by combined analysis involving the bioinformatics algorithm miRanda and whole genome expression. Results. Three TLR4/NF-κB-responsive miRNAs (miR-15a, miR-744, and miR-1196) were significantly upregulated in the muscles following ischemia-reperfusion injury. The combined in silico and whole genome microarray approaches identified 5, 4, and 20 potential target genes for miR-15a, miR-744, and miR-1196, respectively. Among the 3 genes (Zbed4, Lrsam1, and Ddx21) regulated by at least 2 of the 3 upregulated miRNAs, Lrsam1 and Ddx21 are known to be associated with the innate immunity pathway. Conclusions. This study profiled TLR4/NF-κB-responsive miRNAs and their potential target genes in mouse skeletal muscle subjected to ischemia-reperfusion injury.

Regulatory and Effector Helper T-Cell Profile after Nerve Xenografting in the Toll-Like Receptor-Deficient Mice

Introduction: The balance between regulatory T cells (Tregs) and effector T help cells (Th cells) is critical for the control of adaptive immune response during nerve transplantation. However, whether the homeostasis of immune regulation between Tregs and Th cells requires toll-like receptor (TLR) signaling is unclear. The aim of this study is to profile the distribution of spleen Tregs and Th cells in a mouse model of nerve xenografting in the TLR2 and NF-κB gene knockout mice. Methods: The sciatic nerve was taken from a SD rat or an allogeneic mouse and transplanted to a right back leg of recipient C57BL/6, TLR2-/-, or NF-κB-/- mice by subcutaneous transplantation. After 7 days, the T lymphocytes were then isolated from spleen, stained with phenotyping kits, and analyzed by flow cytometry. Results: The results showed that Tregs were decreased after nerve xenografting in the recipient C57BL/6 mouse. In addition, nerve xenografting also increased the Th1 and Th17 but not the Th2 cell populations. In contrast, amelioration of the Tregs elimination was found in TLR2-/- and NF-κB-/- mice after transplantation of the nerve xenograft. Moreover, the mice lacking TLR2 or NF-κB showed attenuation of the increase in Th1 and Th17 cells after nerve xenografting. Conclusions: TLR signaling is involved in T cell population regulation during tissue transplantation. Knock-out of TLR2 and NF-κB prevented Tregs elimination and inhibited Th1- and Th17-driven immune response after nerve xenografting. This study highlighted the potential of inhibiting TLR signaling to modulate T cell-mediated immune regulation to facilitate tolerance to nerve transplantation.

Identification of Circulating miRNAs in a Mouse Model of Nerve Allograft Transplantation under FK506 Immunosuppression by Illumina Small RNA Deep Sequencing.

Background. This study aimed to establish the expression profile of circulating microRNAs (miRNAs) during nerve allotransplantation in the presence and absence of FK506 immunosuppression. Methods. A 1 cm BALB/c donor sciatic nerve graft was transplanted into the sciatic nerve gaps created in recipient C57BL/6 mice with or without daily FK506 immunosuppression [1 mg/(kg·d)]. At 3, 7, and 14 d after nerve allotransplantation, serum samples were collected for miRNA expression analysis by Illumina small RNA deep sequencing. Results. Sequence analysis showed that the dominant size of circulating small RNAs after nerve allotransplantation was 22 nucleotides, followed by 23-nucleotide sequences. Nine upregulated circulating miRNAs (let-7e-5p, miR-101a-3p, miR-151-5p, miR-181a-5p, miR-204-5p, miR-340-5p, miR-381-3p, miR-411-5p, miR-9-5p, and miR-219-2-3p) were identified at 3 d, but none was identified at 7 or 14 d. Among them, miR-9-5p had the highest fold-change of >50-fold, followed by miR-340-5p with 38.8-fold. The presence of these nine miRNAs was not significant at 7 and 14 d after nerve allotransplantation with or without immunosuppression, showing that these miRNAs are not ideal biomarkers for monitoring rejection of deep-buried nerve allografts, a response usually observed later. Conclusions. We identified nine upregulated circulating miRNAs, which may have a biological function, particularly during the early stages after nerve allotransplantation under FK506 immunosuppression.