Abstract
Sepsis is a systemic inflammatory response syndrome caused by infection. Lipopolysaccharide (LPS) has been reported to induce inflammatory responses, and long non-coding RNA highly up-regulated in liver cancer (HULC) expression was associated with the progression of sepsis. But the role and underlying mechanism of HULC in LPS-induced sepsis remain unclear. Cell viability and apoptosis were measured by methyl thiazolyl tetrazolium (MTT) and flow cytometry assays, respectively. The levels of apoptosis-related proteins, inflammatory cytokines and transient receptor potential melastatin7 (TRPM7) were detected by western blot. Reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected by dichloro-dihydro-fluorescein diacetate (DCFH-DA) method using commercial kit. HULC, microRNA-204-5p (miR-204-5p) and TRPM7 expressions in serum of sepsis patients and human umbilical vein endothelial cells (HUVECs) were examined by quantitative real-time polymerase chain reaction (qRT-PCR). Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to confirm the interaction between HULC and miR-204-5p, miR-204-5p and TRPM7. LPS stimulation restrained cell viability and facilitated apoptosis, inflammatory injury and oxidative stress in HUVECs. HULC and TRPM7 were increased and accompanied with decreased miR-204-5p expression in serum of sepsis patients. A significant negative correlation between miR-204-5p and HULC or TRPM7 was observed, and there was a positive relationship between expressions of HULC and TRPM7. Importantly, LPS inhibited the cell viability and induced apoptosis, inflammatory injury and oxidative stress of HUVECs by up-regulating the expressions of HULC and TRPM7, and down-modulating miR-204-5p expression. Mechanically, HULC positively regulated TRPM7 expression by sponging miR-204-5p in HUVECs. LPS impaired cell viability, and promoted cell apoptosis, inflammatory response and oxidative stress in HUVECs by regulating HULC/miR-204-5p/TRPM7 axis.
Highlights
Sepsis is a systemic inflammatory disease caused by severe trauma, burns and postoperative infections
After human umbilical vein endothelial cells (HUVECs) were treated with LPS, western blot detected that the expression levels of B-cell lymphoma-2 (Bcl-2)-associated X (Bax) and cleaved-caspase3 were increased (P = 0.0002 and 0.0002), while Bcl-2 was decreased (P = 0.0006, Figure 1C), which further indicated that LPS could promote apoptosis of HUVECs
To explore the effects of LPS on cellular redox status in HUVECs, we evaluated the levels of Reactive oxygen species (ROS), superoxide dismutase (SOD) and MDA
Summary
Sepsis is a systemic inflammatory disease caused by severe trauma, burns and postoperative infections. It develops rapidly and can lead to multiple organ failure [1]. Lipopolysaccharide (LPS), which is made up of lipids and polysaccharides, is an endotoxin that is released from bacterial membranes and binds to receptors on the surface of endothelial cells, thereby acting as a toxic agent that causes severe inflammation [3]. LPS has been reported to induce sepsis by regulating the growth of endothelial cells, inflammatory factors and oxidative stress factors [4,5]. The exact mechanism by which LPS affects endothelial cell activity and induces cellular inflammation is still not fully understood
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