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Updated: May 20, 2026
Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach
Published on: May 2, 2018
Whole blood-derived microRNA signatures in mice exposed to lipopolysaccharides
Ching-Hua Hsieh1, Cheng-Shyuan Rau, Jonathan Chris Jeng
1Department of Plastic and Reconstructive Surgery, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
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.
Insights
Lipopolysaccharide (LPS) exposure in mice significantly altered whole blood microRNA (miRNA) expression, identifying specific miRNAs as potential biomarkers. These findings highlight a distinct miRNA signature linked to Gram-negative bacterial invasion, crucial for sepsis research.
Area of Science:
- Immunology
- Molecular Biology
- Genomics
Background:
- Lipopolysaccharide (LPS) is a key mediator in Gram-negative bacterial infections, implicated in sepsis pathogenesis.
- Understanding host response at the molecular level, particularly microRNA (miRNA) expression, is crucial for diagnosing and managing sepsis.
Purpose of the Study:
- To investigate the changes in whole blood miRNA expression following intraperitoneal lipopolysaccharide (LPS) administration in mice.
- To identify specific miRNAs that can serve as biomarkers for LPS exposure and Gram-negative bacterial invasion.
Main Methods:
- C57BL/6 mice were injected with varying concentrations of LPS from different Gram-negative bacteria.
- Whole blood and tissue samples were collected at multiple time points (2, 6, 24, 72 h) for miRNA expression analysis using miRNA arrays and real-time RT-PCR.
- Expression levels were compared between LPS-injected, lipoteichoic acid (LTA)-injected, and Tlr4(-/-) mice.
Main Results:
- LPS injection led to a significant upregulation of 15 miRNAs in whole blood, with dose- and time-dependent patterns.
- Specific miRNA targets (let-7d, miR-15b, miR-16, miR-25, miR-92a, miR-103, miR-107, miR-451) showed induced expression peaking within 6 hours.
- Lower expression of certain miRNAs was observed in Tlr4(-/-) mice, and LTA induced a different miRNA profile compared to LPS.
Conclusions:
- A distinct whole blood-derived miRNA signature was identified in response to LPS from Gram-negative bacteria.
- These whole blood miRNAs show promise as sensitive biomarkers for detecting LPS exposure.
- The findings contribute to understanding the host response to bacterial infection and developing diagnostic tools for sepsis.
