miR-199a-5p Exacerbated Intestinal Barrier Dysfunction through Inhibiting Surfactant Protein D and Activating NF-κB Pathway in Sepsis

MicroRNA-483-3p Inhibitor Ameliorates Sepsis-Induced Intestinal Injury by Attenuating Cell Apoptosis and Cytotoxicity Via Regulating HIPK2

Sepsis is a life-threatening syndrome that can result in multi-organ dysfunction. MicroRNA (miR)-483-3p was previously demonstrated to be upregulated in sepsis patients; however, its specific functions in sepsis-triggered intestinal injury remain unclarified. Human intestinal epithelial NCM460 cell line was stimulated with lipopolysaccharide (LPS) to mimic sepsis-induced intestinal injury in vitro. Terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining was utilized for examining cell apoptosis. Western blotting and real time quantitative polymerase chain reaction (RT-qPCR) were used for detecting molecular protein and RNA levels. LPS-induced cytotoxicity was determined by measuring concentrations of lactate dehydrogenase (LDH), diamine oxidase (DAO) and fatty acid binding protein 2 (FABP2). Luciferase reporter assay was utilized for verifying the interaction between miR-483-3p and homeodomain interacting protein kinase 2 (HIPK2). Inhibiting miR-483-3p alleviates LPS-triggered NCM460 cell apoptosis and cytotoxicity. miR-483-3p targeted HIPK2 in LPS-stimulated NCM460 cells. Knockdown of HIPK2 reversed the above effects mediated by miR-483-3p inhibitor. Inhibiting miR-483-3p ameliorates LPS-triggered apoptosis and cytotoxicity by targeting HIPK2.

Ghrelin/GHSR Axis Induced M2 Macrophage and Alleviated Intestinal Barrier Dysfunction in a Sepsis Rat Model by Inactivating E2F1/NF-κB Signaling

Sepsis is an inflammatory reaction disorder state that is induced by infection. The activation and regulation of the immune system play an essential role in the development of sepsis. Our previous studies have shown that ghrelin ameliorates intestinal dysfunction in sepsis. Very little is known about the mechanism of ghrelin and its receptor (GHSR) on the intestinal barrier and the immune function of macrophage regulation. Our research is to investigate the regulatory effect and molecular mechanism of the ghrelin/GHSR axis on intestinal dysfunction and macrophage polarization in septic rats. A rat model of sepsis was established by cecal ligation and puncture (CLP) operation. Then, the sepsis rats were treated with a ghrelin receptor agonist (TZP-101) or ghrelin inhibitor (obestatin). The results suggested that TZP-101 further enhanced ghrelin and GHSR expressions in the colon and spleen of septic rats and obestatin showed the opposite results. Ghrelin/GHSR axis ameliorated colonic structural destruction and intestinal epithelial tight junction injury in septic rats. In addition, the ghrelin/GHSR axis promoted M2-type polarization of macrophages, which was characterized by the decreases of IL-1β, IL-6, and TNF-α, as well as the increase of IL-10. Mechanistically, the ghrelin/GHSR axis promoted E2F2 expression and suppressed the activation of the NF-κB signaling pathway in septic rats. Collectively, targeting ghrelin/GHSR during sepsis may represent a novel therapeutic approach for the treatment of intestinal barrier injury.

Inhibition of PFKFB Preserves Intestinal Barrier Function in Sepsis by Inhibiting NLRP3/GSDMD

Intestinal barrier dysfunction is associated with the occurrence and development of sepsis. Further, aerobic glycolysis plays an essential role in inflammation and cell death. This study is aimed at investigating the protective effect and mechanism of PFKFB3 inhibition on intestinal barrier dysfunction in sepsis mice. Sepsis mouse models were established by cecal ligation and puncture (CLP) in wild-type mice and Gsdmd^-/- mice. The results showed that the expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) in the small intestines was significantly upregulated in sepsis. 3-(3-Pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO), the specific inhibitor of PFKFB3, and Gsdmd gene knockout significantly inhibited the inflammatory response and cell death caused by sepsis, thus alleviating intestinal damage and barrier dysfunction. 3PO was also shown to significantly inhibit oxidative stress and NLRP3/caspase-1/GSDMD-dependent cell pyroptosis in the small intestines. The in vitro studies revealed that 3PO reduced NLRP3/caspase-1/GSDMD-dependent cell pyroptosis by inhibiting ROS. Taken together, our results suggest that PFKFB3 is involved in inflammation, oxidative stress, and pyroptosis during sepsis and enhances intestinal damage, which may provide important clues about the potential targets to be exploited in this highly lethal disease.

The protective mechanism of salidroside modulating miR-199a-5p/TNFAIP8L2 on lipopolysaccharide-induced MLE-12 cells

OBJECTIVES

Salidroside is used for treating inflammation-based diseases; however, its molecular mechanism is unclear. In this study, we determined the protective role of salidroside on the endotoxin-induced damage caused to the mouse alveolar epithelial type II (MLE-12) cells and its underlying mechanism.

METHODS

An in vitro model for acute lung injury was constructed by inducing the MLE-12 cells using lipopolysaccharide (lipopolysaccharides, 1 mg/L). Then, The MTT assay was conducted to assess the survival rate of the MLE-12 cells in the different groups. After the treatment, apoptosis of MLE-12 cells was determined, and the mRNA and protein expression of miR-199a-5p, HMGB1, NF-kB65, TNFAIP8L2, p-IkB-α, and TLR4 was estimated by Western Blotting and RT-PCR. ELISA was also used to measure the concentration of inflammatory cytokine molecules IL-1β, IL-6, TNF-α, and IL-18 in the cell-free supernatant. Lastly, cell morphology was examined using the AO/EB technique.

RESULTS

We showed that salidroside reduced the protein and gene expression of HMGB1, NF-kB65, miR-199a-5p, p-IkB-α, and TLR4, whereas it increased the gene and protein expression of TNFAIP8L2. Furthermore, it decreased the concentrations of cytokine molecules like IL-1β, IL-6, TNF-α, and IL-18 in the cell-free supernatant. MLE-12 also showed a lower apoptosis rate, higher survival rate, and better cell morphology.

CONCLUSION

Salidroside significantly inhibited the LPS-induced MLE-12 cell damage. Our results suggest that this could be by reducing miR-199a-5p and enhancing TNFAIP8L2 expression.

Modes of action and diagnostic value of miRNAs in sepsis

Sepsis is a clinical syndrome defined as a dysregulated host response to infection resulting in life-threatening organ dysfunction. Sepsis is a major public health concern associated with one in five deaths worldwide. Sepsis is characterized by unbalanced inflammation and profound and sustained immunosuppression, increasing patient susceptibility to secondary infections and mortality. microRNAs (miRNAs) play a central role in the control of many biological processes, and deregulation of their expression has been linked to the development of oncological, cardiovascular, neurodegenerative and metabolic diseases. In this review, we discuss the role of miRNAs in sepsis pathophysiology. Overall, miRNAs are seen as promising biomarkers, and it has been proposed to develop miRNA-based therapies for sepsis. Yet, the picture is not so straightforward because of the versatile and dynamic features of miRNAs. Clearly, more research is needed to clarify the expression and role of miRNAs in sepsis, and to promote the use of miRNAs for sepsis management.

Regulatory Role of Non-Coding RNAs on Immune Responses During Sepsis

Sepsis is resulted from a systemic inflammatory response to bacterial, viral, or fungal agents. The induced inflammatory response by these microorganisms can lead to multiple organ system failure with devastating consequences. Recent studies have shown altered expressions of several non-coding RNAs such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) during sepsis. These transcripts have also been found to participate in the pathogenesis of multiple organ system failure through different mechanisms. NEAT1, MALAT1, THRIL, XIST, MIAT and TUG1 are among lncRNAs that participate in the pathoetiology of sepsis-related complications. miR-21, miR-155, miR-15a-5p, miR-494-3p, miR-218, miR-122, miR-208a-5p, miR-328 and miR-218 are examples of miRNAs participating in these complications. Finally, tens of circRNAs such as circC3P1, hsa_circRNA_104484, hsa_circRNA_104670 and circVMA21 and circ-PRKCI have been found to affect pathogenesis of sepsis. In the current review, we describe the role of these three classes of noncoding RNAs in the pathoetiology of sepsis-related complications.