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Differential signaling effects of Escherichia coli and Staphylococcus aureus in human whole blood indicate distinct regulation of the NRF2 Pathway

ABSTRACT: Escherichia coli and Staphylococcus aureus are two of the most common bacterial species responsible for severe sepsis. While it is observed that they have disparate clinical phenotypes, the signaling differences elicited by each bacteria that drive this variance remain unclear. Therefore, we utilized human whole blood exposed to heat-killed E. coli or S. aureus and measured the transcriptomic signatures. Relative to unstimulated control blood, heat-killed bacteria exposure led to significant dysregulation (up and down-regulated) of >5000 genes for each experimental condition, with a slight increase in gene dysregulation by S. aureus. While there was significant overlap regarding pro-inflammatory gene ontology pathways, heat-killed E. coli had a more considerable impact on purine metabolism than heat-killed S. aureus, which had a more significant effect on nitric oxide-mediated processes. Utilizing Ingenuity Pathway Analysis, it was predicted that nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, a main transcription factor in anti-oxidant responses, was predominately up-regulated in S. aureus relative to E. coli. Further, the use of pharmacologics that preferentially targeted the Nrf2 pathway led to differential cytokine profiles depending on the type of bacterial exposure. These findings reveal a significant inflammatory dysregulation between E. coli and S. aureus and provide insight into the potential of targeting unique pathways to curb the bacteria species-specific response.

ORGANISM(S): Homo sapiens

PROVIDER: GSE237960 | GEO | 2024/01/01

REPOSITORIES: GEO

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Project description:Purpose: The goal of this study is to explore the role of miRNAs in dairy cow response to E. coli and S. aureus, mastitis causing pathogens, is not well understood. Results: The global expression of miRNAs in bovine mammary epithelial cells (MAC-T cells) challenged with heat-inactivated Staphylococcus aureus (S. aureus) or Escherichia coli (E. coli) bacteria (treatments: 6, 12, 24 and 48 hr) and without challenge (control: 0, 6, 12, 24 and 48 hr) was profiled using next-generation-sequencing. A total of 231 known bovine miRNAs were identified with more than 10 counts per million (CPM) in at least one of 13 libraries and 5 miRNAs including bta-miR-21-5p, miR-27b, miR-22-3p, miR-184 and let-7f represented more than 50% of the total reads of known bovine miRNAs. One hundred and fifty novel miRNAs were identified and half of them belong to the bta-miR-2284 family. Seventeen miRNAs were significantly (P<0.05) differentially regulated by the presence of pathogens. E. coli initiated an earlier regulation of miRNAs (6 miRNAs differentially regulated within the first 6 hrs post challenge as compared to one for S. aureus) while S. aureus presented a delayed response. Five differentially expressed miRNAs (Bta-miR184, miR-24-3p, miR-148, miR-486 and bta-let-7a-5p) were unique to E. coli while four (bta-miR-2339, miR-499, miR-23a and miR-99b) were unique to S. aureus. In addition, our study revealed a temporal differential regulation of five miRNAs (bta-miR-193a-3p, miR-423-5p, miR-30b-5p, miR-29c and miR-un116) in unchallenged cells. Target gene predictions of pathogen differentially expressed miRNAs indicate a significant enrichment in gene ontology functional categories in development/cellular processes, biological regulation as well as cell growth and death. Furthermore, target genes were significantly enriched in several KEGG (Kyoto encyclopedia of genes and genomes) pathways of the immune system, signal transduction, cellular process, nervous system, development and pathways in human diseases, especially cancer. Conclusion: Using next-generation sequencing, our study identified 150 novel bovine miRNAs and revealed a pathogen directed differential regulation of miRNAs in MAC-T cells with roles in immunity and development. E. coli elicited an earlier differential regulation of miRNAs as opposed to a delayed regulation by S. aureus. Furthermore, target gene prediction showed significant enrichments for functions in different biological and cellular processes as well as KEGG pathways in immunity, development and human diseases. Our study provides a further confirmation of the involvement of mammary epithelia cells in contributing to the immune response to infecting pathogens and suggests the potential of miRNAs to serve as biomarkers for diagnosis of mastitis and development of control measures. Bovine mammary epithelial cells (MAC-T cells) challenged with heat-inactivated Staphylococcus aureus (S. aureus) or Escherichia coli (E. coli) bacteria (treatments: 6, 12, 24 and 48 hr) and without challenge (control: 0, 6, 12, 24 and 48 hr) was profiled using next-generation-sequencing, no replicates, using illumina HiScanSQ platform.

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Project description:We profiled the expression of circulating microRNAs (miRNAs) in mice exposed to gram-positive and gram-negative bacteria using Illumina small RNA deep sequencing. Recombinant-specific gram-negative pathogen Escherichia coli (Xen14) and gram-positive pathogen Staphylococcus aureus (Xen29) were used to induce bacterial infection in mice at a concentration of 1 × 108 bacteria/100 μL of phosphate buffered saline (PBS). Small RNA libraries generated from the serum of mice after exposure to PBS, Xen14, Xen29, and Xen14+Xen29 via the routes of subcutaneous injection (I), cut wound (C), or under grafted skin (S) were analyzed using an Illumina HiSeq2000 Sequencer. Following exposure to gram-negative bacteria alone, no differentially expressed miRNA was found in the injection, cut, or skin graft models. Exposure to mixed bacteria induced a similar expression pattern of the circulating miRNAs to that induced by gram-positive bacterial infection. Upon gram-positive bacterial infection, 9 miRNAs (mir-193b-3p, mir-133a-1-3p, mir-133a-2-3p, mir-133a-1-5p, mir-133b-3p, mir-434-3p, mir-127-3p, mir-676-3p, mir-215-5p) showed upregulation greater than 4-fold with a p-value < 0.01. Among them, mir-193b-3p, mir-133a-1-3p, and mir-133a-2-3p presented the most common miRNA targets expressed in the mice exposed to gram-positive bacterial infection. Male C57BL/6 mice (age, 10–12 weeks; weight, 30–35 g) were purchased from BioLasco (Yi-Lan, Taiwan). The mice were anesthetized by intraperitoneal injection of an anesthetic cocktail consisting of 0.1 mg/g ketamine and 0.01 mg/g xylazine. The anesthetized mice were restrained in a supine position on a heated pad to maintain body temperature at 37°C. Recombinant-specific gram-negative pathogen Escherichia coli (Xen14) and gram-positive pathogen Staphylococcus aureus (Xen29) purchased from Caliper (Caliper, USA) were used to induce bacterial infection in the mice at a concentration of 1 × 108 bacteria/100 μL of phosphate buffered saline (PBS). To create mixed gram-negative and gram-positive bacterial infection, 1 × 108 Xen14 bacteria and 1 × 108 Xen29 bacteria/100 μL of PBS were used for wound contamination. Three animal models were used to create bacterial infection routes: subcutaneous injection (hereafter referred to as (I)), cut wound (hereafter referred to as (C)), and skin grafting (hereafter referred to as (S)). In the (I) model, E. coli and/or S. aureus suspensions were injected subcutaneously into the backs of the mice using an Fr. 25 needle. In the (C) model, a 1 cm incision wound was created in the midline of the back, smeared with E. coli and/or S. aureus suspension, and the wound was closed directly with a 4-0 nylon suture. In the (S) model, a 1×1 cm rectangular full- thickness skin graft was lifted from the backs of the mice, E. coli and/or S. aureus suspensions were spread over the wound bed, and the skin graft was reattached and closed with a 4-0 nylon suture. An additional group of animals in each of these three models was inoculated with PBS to serve as a negative control. Small RNA libraries generated from the serum of mice after exposure to PBS, Xen14, Xen29, and Xen14+Xen29 via the routes of subcutaneous injection (I), cut wound (C), or under grafted skin (S) were analyzed using an Illumina HiSeq2000 Sequencer.

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Differential signaling effects of Escherichia coli and Staphylococcus aureus in human whole blood indicate distinct regulation of the NRF2 Pathway

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