Project description:Host immune responses during late-onset sepsis (LOS) in very preterm infants are poorly characterised due to a complex and dynamic pathophysiology and challenges in working with small available blood volumes. We present here an unbiased transcriptomic analysis of whole peripheral blood from very preterm infants at the time of LOS. RNA-Seq was performed on peripheral blood samples (6 – 29 days postnatal age) taken at the time of suspected LOS from very preterm infants <30 weeks gestational age. Infants were classified based on blood culture positivity and elevated C-reactive protein concentrations as having confirmed LOS (n=5), possible LOS (n=4) or no LOS (n=9). Bioinformatics and statistical analyses performed included pathway over-representation and protein-protein interaction network analyses. Plasma cytokine immunoassays were performed to validate differentially expressed cytokine pathways.The blood leukocyte transcriptional responses of infants with confirmed LOS differed significantly from infants without LOS (1,317 differentially expressed genes). However, infants with possible LOS could not be distinguished from infants with no LOS or confirmed LOS. Transcriptional alterations associated with LOS included genes involved in pathogen recognition (mainly TLR pathways), cytokine signalling (both pro-inflammatory and inhibitory responses), immune and haematological regulation (including cell death pathways), and metabolism (altered cholesterol biosynthesis). At the transcriptional-level cytokine responses during LOS were characterised by over-representation of IFN-α/β, IFN-γ, IL-1 and IL-6 signalling pathways and up-regulation of genes for inflammatory responses. Infants with confirmed LOS had significantly higher levels of IL-1α and IL-6 in their plasma. Blood responses in very preterm infants with LOS are characterised by altered host immune responses that appear to reflect unbalanced immuno-metabolic homeostasis.
Project description:The use of assisted reproductive technologies (ART) can induce a congenital overgrowth condition in humans and ruminants, namely Beckwith-Wiedemann syndrome (BWS) and large offspring syndrome (LOS), respectively. Shared phenotypes and epigenotypes have been found between BWS and LOS. We have observed global misregulation of transcripts in bovine foetuses with LOS. microRNAs (miRNAs) are important post-transcriptional gene expression regulators. We hypothesize that there is miRNA misregulation in LOS and that this misregulation is shared with BWS. In this study, small RNA sequencing was conducted to investigate miRNA expression profiles in bovine and human samples. We detected 407 abundant known miRNAs and predicted 196 putative miRNAs from the bovine sequencing results and identified 505 abundant miRNAs in human tongue. Differentially expressed miRNAs (DE-miRNAs) were identified between control and LOS groups in all tissues analysed as well as between BWS and control human samples. DE-miRNAs were detected from several miRNA clusters including DLK1-DIO3 genomic imprinted cluster in LOS and BWS. DNA hypermethylation was associated with downregulation of miRNAs in the DLK1-DIO3. mRNA targets of the DE-miRNAs were predicted and signalling pathways associated with control of organ size (including the Hippo signalling pathway), cell proliferation, apoptosis, cell survival, cell cycle, and cell adhesion were found to be enriched with these genes. Yes associated protein 1 (YAP1) is the core effector of the Hippo signalling pathway, and increased level of active (non-phosphorylated) YAP1 protein was detected in skeletal muscle of LOS foetuses. Overall, our data provide evidence of miRNA misregulation in LOS and BWS.
Project description:Large offspring syndrome (LOS) and Beckwith-Wiedemann syndrome are a similar epigenetic congenital overgrowth conditions in ruminants and humans, respectively. We have reported global loss-of-imprinting, methylome epimutations, and global misregulation of genes in LOS. However, less than 4% of gene misregulation can be explained with short range (<20Kb) alterations in DNA methylation. Therefore, we hypothesized that methylome epimutations in LOS affect chromosome architecture which results in misregulation of genes located at distances >20Kb in cis and also in trans (other chromosomes). Our analyses focused on two imprinted domains that frequently show misregulation in these syndromes, namely KvDMR1 and IGF2R. Using bovine fetal fibroblasts, we identified CTCF binding at IGF2R but not KvDMR1, and allele-specific chromosome architecture of these domains in controls. In LOS, analyses identified erroneous long-range contacts and clustering tendency in the direction of expression of misregulated genes. In conclusion, altered chromosome architecture is involved in the etiology of LOS.