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Bronchoalveolar Lavage Exosomes in Lipopolysaccharide-induced Septic Lung Injury
Published on: May 21, 2018
Exosomal miR-146a-5p Derived from HSCs Accelerates Sepsis-induced Liver Injury by Suppressing KLF-4
Ziyi Sheng1, Hua Song1, Xianzhi Gao1
1Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing, 40010, China.
Abstract:
This study aimed to investigate whether and how lipopolysaccharide (LPS) activated hepatic stellate cells (HSCs) regulate macrophage activity and to explore the impact of microRNAs (miRNAs) in exosomes from HSCs on this process. Mice subjected to LPS or cecal ligation and puncture (CLP) were used to explore sepsis-induced liver injury. Liver injury was evaluated using HE staining, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. LPS-Exo or N-LPS-Exo from HSCs were added to hepatic macrophages, and iNOS, IL-1β, and TNF-α expression was detected via Western blotting. miRNA microarray analysis and PCR were used to evaluate differentially expressed miRNAs between LPS-Exo and N-LPS-Exo. Target genes were screened using the TargetScan database and verified with luciferase assays and WB. Inflammation and macrophage activity were observed in vivo using HE and CD86 staining in mice injected with PKH67-labeled LPS-Exo or N-LPS-Exo. Sepsis-related liver injury activates hepatic stellate cells, which regulate macrophage activity through exosomes. Specifically, exosomal miR-146a-5p secreted by hepatic stellate cells targets KLF-4, regulating the macrophage inflammatory response through the JNK signaling pathway. Exosomes containing miRNA-146a-5p released from HSCs following LPS treatment may increase macrophage sensitivity to LPS and trigger an inflammatory response. Exosomal miR-146a-5p derived from HSCs accelerates sepsis-induced liver injury by suppressing KLF-4 expression.
Insights
Lipopolysaccharide (LPS) activates hepatic stellate cells (HSCs) to release exosomes containing miR-146a-5p. These exosomes suppress KLF-4 in macrophages, exacerbating sepsis-induced liver injury and inflammation.
Area of Science:
- Hepatology
- Immunology
- Molecular Biology
Background:
- Sepsis-induced liver injury involves complex cellular crosstalk.
- Hepatic stellate cells (HSCs) and macrophages play critical roles in liver inflammation.
- Exosomes mediate intercellular communication, influencing inflammatory responses.
Purpose of the Study:
- To investigate how lipopolysaccharide (LPS)-activated HSCs regulate macrophage activity.
- To explore the role of exosomal microRNAs (miRNAs) from HSCs in sepsis-related liver injury.
- To elucidate the specific molecular mechanisms involved in HSC-macrophage communication during liver injury.
Main Methods:
- In vivo mouse models of sepsis-induced liver injury (LPS and cecal ligation and puncture).
- In vitro studies using hepatic macrophages treated with exosomes from LPS-activated HSCs (LPS-Exo) or normal HSCs (N-LPS-Exo).
- Analysis of inflammatory markers (iNOS, IL-1β, TNF-α), miRNA expression profiling, target gene validation (KLF-4), and signaling pathway analysis (JNK).
- In vivo tracking of exosome uptake and assessment of inflammation using histological and immunohistochemical staining.
Main Results:
- Sepsis-induced liver injury activates HSCs, leading to the release of exosomes that modulate macrophage activity.
- Exosomes derived from LPS-activated HSCs (LPS-Exo) contain significantly altered miRNA profiles compared to N-LPS-Exo.
- Exosomal miR-146a-5p from HSCs targets and suppresses KLF-4 expression in macrophages.
- This suppression of KLF-4 by exosomal miR-146a-5p activates the JNK signaling pathway, promoting macrophage inflammation.
- In vivo administration of LPS-Exo exacerbated liver injury and inflammation, correlating with increased macrophage activation.
Conclusions:
- Activated HSCs communicate with macrophages via exosomes during sepsis-induced liver injury.
- Exosomal miR-146a-5p released by HSCs is a key mediator, promoting inflammation by targeting KLF-4 and activating the JNK pathway.
- HSC-derived exosomal miR-146a-5p accelerates sepsis-induced liver injury by enhancing macrophage inflammatory responses.
