ABSTRACT
Inflammatory reaction dominated by defense response will arise against infection and trauma. As an important proinflammatory cytokine, high mobility group box 1 (HMGB1) is widely expressed in all nuclear cells to mediate the inflammatory response. However, the biological functions of HMGB1 in inflammation vary depending on the type of HMGB1 protein modification and the localization in the cell. HMGB1 protein will be modified as acetylation of lysine residues, methylation of lysine residues, oxidation of cysteine residues, phosphorylation of serine residues, glycosylation of asparagine residues, adenosine diphosphate-ribosylation and lactylation of the protein in the nucleus, migrate from the nucleus to the cytoplasm, and release into the extracellular compartment. Extracellular HMGB1 can bind to receptors for advanced glycation end products (RAGE) and Toll-like receptors, activate cells and regulate inflammatory responses. The authors review the research progress in regulatory mechanism of HMGB1 in inflammation response from aspects of its post-translational modifications, releases, biological roles and binding receptors, hoping to provide theoretical basis for finding the targets of inflammation intervention.
ABSTRACT
Objective@#To investigate the effects of terlipressin (TP) on blood pressure and survival in septic mice following trauma and its mechanism.@*Methods@#① Survival experiment: 120 male C57BL/6 mice aged 6-8 weeks were enrolled, the posttraumatic sepsis mice model was reproduced by traumatic hemorrhage (bilateral femoral fracture + 45% of total blood loss) followed by cecal ligation and puncture (CLP) after 8 hours. Intraperitoneal injection of TP was used for intervention. Sixty model mice were used to observe the effect of 0.05 μg/g TP at different intervention times (the drug was given immediately after traumatic hemorrhage + the administration was repeated after 6 hours, the drug was given immediately after traumatic hemorrhage + the administration was repeated every 6 hours until the end of the experiment, the drug was given at 4 hours after CLP + the administration was repeated every 6 hours until the end of the experiment) on 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention time of TP. The other 60 model mice were used to observe the effect of different TP intervention doses (0.01, 0.05, 0.25 μg/g) at the best intervention time on the 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention dose of TP. ② Intervention experiment: the other 45 mice were enrolled, and they were randomly divided into traumatic hemorrhage + sham group (TH+sham group, only laparotomy without CLP), TH+CLP group, and TH+CLP+TP group (the best intervention time and dose of TP shown by survival experiment were used), with 15 mice in each group. Mean arterial pressure (MAP) of mice was monitored continuously. The orbital whole blood was collected at 2 hours after successful reproduction of the model, and the lung tissues were harvested at 12 hours and 24 hours, respectively. The pathological changes in lung tissue were observed with light microscope. The contents of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in serum and lung tissue were determined by enzyme linked immunosorbent assay (ELISA). The expressions of IL-1β and TNF-α mRNA in lung tissue were determined by real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The expressions of nuclear factor-κB p65 (NF-κB p65) in the nucleus and cytoplasm of lung tissue were determined by Western Blot.@*Results@#① Survival experiment results showed that the 48-hour cumulative survival rate of mice was highest with TP intervention by 0.05 μg/g administration immediately after traumatic hemorrhage and repeated every 6 hours, which was the best intervention method of TP. ② Intervention experiment results showed that the pulmonary alveolar wall fracture accompanied by inflammatory cell infiltration was found at 12 hours after the successful reproduction of traumatic sepsis model, and the pathological damage was gradually increased with time prolongation. MAP was decreased sharply after traumatic hemorrhage, and it was continued to decrease after two-hit of CLP. The contents of IL-1β and TNF-α in serum and lung tissue, the expressions of IL-1β and TNF-α mRNA in lung tissue, and expressions of NF-κB p65 protein in cytoplasm and nucleus of TH+CLP group were significantly higher than those in TH+sham group. Compared with TH+CLP group, the pathological changes in lung tissue were improved significantly, and the MAP was decreased gently after TP intervention, the levels of inflammatory mediators in serum were significantly decreased [IL-1β (pg/L): 164.32±25.25 vs. 233.11±23.02, TNF-α (pg/L): 155.56±31.47 vs. 596.38±91.50, both P < 0.05], and their expressions in lung tissue [IL-1β content (ng/mg): 262.68±16.56 vs. 408.15±17.85, IL-1β mRNA (2-ΔΔCt): 2.63±0.68 vs. 6.22±0.74; TNF-α content (ng/mg): 311.07±17.35 vs. 405.04±24.83, TNF-α mRNA (2-ΔΔCt): 2.04±0.62 vs. 5.32±0.55, all P < 0.01], and NF-κB p65 protein expressions were significantly down-regulated (gray value: 0.47±0.01 vs. 1.28±0.05 in cytoplasm, 0.45±0.02 vs. 1.95±0.06 in nucleus, both P < 0.01].@*Conclusions@#The continuous intervention with TP 0.05 μg/g administration immediately after traumatic hemorrhage and repeated every 6 hours could improve the MAP of mice with traumatic sepsis, and improve the prognosis. The mechanism may be related to alleviating the inflammatory response and inhibiting the activation of the NF-κB signaling pathway in the lung tissue.
ABSTRACT
OBJECTIVE@#To investigate the effects of terlipressin (TP) on blood pressure and survival in septic mice following trauma and its mechanism.@*METHODS@#(1) Survival experiment: 120 male C57BL/6 mice aged 6-8 weeks were enrolled, the posttraumatic sepsis mice model was reproduced by traumatic hemorrhage (bilateral femoral fracture + 45% of total blood loss) followed by cecal ligation and puncture (CLP) after 8 hours. Intraperitoneal injection of TP was used for intervention. Sixty model mice were used to observe the effect of 0.05 μg/g TP at different intervention times (the drug was given immediately after traumatic hemorrhage + the administration was repeated after 6 hours, the drug was given immediately after traumatic hemorrhage + the administration was repeated every 6 hours until the end of the experiment, the drug was given at 4 hours after CLP + the administration was repeated every 6 hours until the end of the experiment) on 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention time of TP. The other 60 model mice were used to observe the effect of different TP intervention doses (0.01, 0.05, 0.25 μg/g) at the best intervention time on the 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention dose of TP. (2) Intervention experiment: the other 45 mice were enrolled, and they were randomly divided into traumatic hemorrhage + sham group (TH+sham group, only laparotomy without CLP), TH+CLP group, and TH+CLP+TP group (the best intervention time and dose of TP shown by survival experiment were used), with 15 mice in each group. Mean arterial pressure (MAP) of mice was monitored continuously. The orbital whole blood was collected at 2 hours after successful reproduction of the model, and the lung tissues were harvested at 12 hours and 24 hours, respectively. The pathological changes in lung tissue were observed with light microscope. The contents of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in serum and lung tissue were determined by enzyme linked immunosorbent assay (ELISA). The expressions of IL-1β and TNF-α mRNA in lung tissue were determined by real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The expressions of nuclear factor-κB p65 (NF-κB p65) in the nucleus and cytoplasm of lung tissue were determined by Western Blot.@*RESULTS@#(1) Survival experiment results showed that the 48-hour cumulative survival rate of mice was highest with TP intervention by 0.05 μg/g administration immediately after traumatic hemorrhage and repeated every 6 hours, which was the best intervention method of TP. (2) Intervention experiment results showed that the pulmonary alveolar wall fracture accompanied by inflammatory cell infiltration was found at 12 hours after the successful reproduction of traumatic sepsis model, and the pathological damage was gradually increased with time prolongation. MAP was decreased sharply after traumatic hemorrhage, and it was continued to decrease after two-hit of CLP. The contents of IL-1β and TNF-α in serum and lung tissue, the expressions of IL-1β and TNF-α mRNA in lung tissue, and expressions of NF-κB p65 protein in cytoplasm and nucleus of TH+CLP group were significantly higher than those in TH+sham group. Compared with TH+CLP group, the pathological changes in lung tissue were improved significantly, and the MAP was decreased gently after TP intervention, the levels of inflammatory mediators in serum were significantly decreased [IL-1β (pg/L): 164.32±25.25 vs. 233.11±23.02, TNF-α (pg/L): 155.56±31.47 vs. 596.38±91.50, both P < 0.05], and their expressions in lung tissue [IL-1β content (ng/mg): 262.68±16.56 vs. 408.15±17.85, IL-1β mRNA (2-Δ ΔCt): 2.63±0.68 vs. 6.22±0.74; TNF-α content (ng/mg): 311.07±17.35 vs. 405.04±24.83, TNF-α mRNA (2-Δ ΔCt): 2.04±0.62 vs. 5.32±0.55, all P < 0.01], and NF-κB p65 protein expressions were significantly down-regulated (gray value: 0.47±0.01 vs. 1.28±0.05 in cytoplasm, 0.45±0.02 vs. 1.95±0.06 in nucleus, both P < 0.01].@*CONCLUSIONS@#The continuous intervention with TP 0.05 μg/g administration immediately after traumatic hemorrhage and repeated every 6 hours could improve the MAP of mice with traumatic sepsis, and improve the prognosis. The mechanism may be related to alleviating the inflammatory response and inhibiting the activation of the NF-κB signaling pathway in the lung tissue.