Propofol Protects Rats and Human Alveolar Epithelial Cells Against Lipopolysaccharide-Induced Acute Lung Injury via Inhibiting HMGB1 Expression.

Wang X ，Liu C ，Wang G 《-》

Ulinastatin post-treatment attenuates lipopolysaccharide-induced acute lung injury in rats and human alveolar epithelial cells.

Luo Y ，Che W ，Zhao M 《-》

The protective effect of dexmedetomidine on LPS-induced acute lung injury through the HMGB1-mediated TLR4/NF-κB and PI3K/Akt/mTOR pathways.

The aim of present study was to evaluate the protective effects of dexmedetomidine (DEX) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and investigate its possible mechanisms mediated by HMGB1. In vivo, pulmonary pathology observation and myeloperoxidase (MPO) activity were also examined to evaluate the protective effect of DEX in the lungs. Tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in bronchoalveolar lavage fluid (BALF), serum and lung tissues LPS-induced rats were detected. The oxidative indices including superoxide dismutase (SOD), Malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in serum were also determined. Additionally, nitric oxide (NO), TNF-α, IL-6 and IL-1β, MDA, SOD and GSH-Px in the supernatants of LPS-induced BEAS-2B cells were measured. Furthermore, we detected the protein expression of high mobility group box-1 protein (HMGB1), Toll-like receptor 4 (TLR4), myeloid differentiating factor 88 (MyD88), inhibitor of NF-κB (IκBα), p-IκBα, nuclear factor kappa-B (NF-κB), p-NF-κB, phosphatidylinositol 3'-kinase (PI3K), p-PI3K, protein kinase B (Akt), p-Akt, mammalian target of rapamycin (mTOR) and p-mTOR in LPS-induced ALI rats and LPS-induced BEAS-2B cells. Immunohistochemical and immunofluorescence analyses of HMGB1 in lung tissues or BEAS-2B cells were also conducted to evaluate the mechanisms of DEX. DEX effectively attenuated pulmonary pathology, and ameliorated the levels of MPO, SOD, MDA, GSH-Px, TNF-α, IL-6, IL-1β and NO in LPS-stimulated rats and BEAS-2B cells. Additionally, treatment with DEX inhibited the expression of HMGB1, TLR4, MyD88, p-IκB, p-NF-κB, p-PI3K, p-Akt and p-mTOR in vivo and in vitro. Immunohistochemical and immunofluorescence analyses also showed that DEX suppressed HMGB1 levels in lung sections and BEAS-2B cells. Treatment with glycyrrhizin, an inhibitor of HMGB1, confirmed that HMGB1 was involved in the mechanism of DEX on LPS-induced ALI. The transfection of HGMB1 siRNA also confirmed these findings in vitro. In conclusion, the present study showed that DEX exerted a protective effect on LPS-induced ALI rats likely through the HMGB1-mediated TLR4/NF-κB and PI3K/Akt/mTOR pathways.

Meng L ，Li L ，Lu S ，Li K ，Su Z ，Wang Y ，Fan X ，Li X ，Zhao G ... -  《-》

Dexmedetomidine attenuates lipopolysaccharide induced acute lung injury in rats by inhibition of caveolin-1 downstream signaling.

Toll-like receptor 4(TLR-4)/nuclear factor-kappa B(NF-κB) pathway plays an important role in inducing acute lung injury (ALI). Studies have proved Dexmedetomidine (Dex) inhibits inflammatory response to mitigate lipopolysaccharide (LPS)-induced ALI and protect against multiorgan injury in various scenarios via restraining TLR-4/NF-κB signaling pathway. Many of the known downstream molecules have been orientated with a protein caveolin-1(Cav-1), which is supposed to take part in regulating TLR4-mediated inflammatory responses. However, its mechanisms have not been confirmed. The aim of this study is to evaluate the protective effects and potential mechanisms of Dex against LPS-induced ALI in male rats. Male rats received tail-vein injection of LPS to form ALI model. Rats were administrated with intraperitoneal injection Dex0.5 h before ALI. At 6 h after LPS injection, bronchoalveolar lavage fluid (BALF) and lung tissue were harvested. We stained the lung tissue sections with hematoxylin eosin (HE) staining to observe the histopathological damage and measure the ALI pathology score. We also measured the wet-to-dry(W/D) weight ratio of lung tissue. Lung myeloperoxidase (MPO) and inflammatory cytokines in the BALF were detected by Enzyme-linked immunosorbent assay(ELISA). Protein levels of Cav-1, TLR-4 and NF-κB in lung tissue were tested by immunohistochemistry method. The mRNA expression of Cav-1, TLR4 and the NF-κB in lung tissue were measured to determine the related mechanisms by quantitative real-time polymerase chain reaction(RT-PCR). It was indicated that Dex pretreatment markedly mitigated pathomorphologic changes and pathological lung injury scores. Besides, Dex pretreatment obviously decreased the W/D weight ratio of lung tissue, attenuated MPO activity significantly, along with LPS-stimulated augment of lung inflammatory cells infiltration in BALF. Moreover, compared with LPS model group, Dex pretreatment apparently increased the protein levels of Cav-1 downregulated by sepsis and decreased the protein levels of TLR-4 and NF-κB in lung tissue. Furthermore, Dex pretreatment apparently upregulated the expression of Cav-1 mRNA, restrained TLR4 and NF-κB mRNA. Dex pretreatment protects against LPS-induced ALI via inhibiting the activation of the TLR-4/NF-kB signaling pathway by upregulating the expression of Cav-1 downregulated by sepsis.

Liu J ，Huang X ，Hu S ，He H ，Meng Z ... -  《-》

Ketamine attenuates sepsis-induced acute lung injury via regulation of HMGB1-RAGE pathways.

High mobility group box protein 1 (HMGB1) and receptor for the advanced glycation end product (RAGE) play important roles in the development of sepsis-induced acute lung injury (ALI). Ketamine is considered to confer protective effects on ALI during sepsis. In this study, we investigated the effects of ketamine on HMGB1-RAGE activation in a rat model of sepsis-induced ALI. ALI was induced in wild type (WT) and RAGE deficient (RAGE(-/-)) rats by cecal ligation and puncture (CLP) or HMGB1 to mimic sepsis-induced ALI. Rats were randomly divided to six groups: sham-operation+normal saline (NS, 10 mL/kg), sham-operation+ketamine (10 mg/kg), CLP/HMGB1+NS (10 mL/kg), CLP/HMGB1+ketamine (5 mg/kg), CLP/HMGB1+ketamine (7.5 mg/kg), and CLP/HMGB1+ketamine (10 mg/kg) groups. NS and ketamine were administered at 3 and 12 h after CLP/HMGB1 via intraperitoneal injection. Pathological changes of lung, inflammatory cell counts, expression of HMGB1 and RAGE, and concentrations of various inflammatory mediators in bronchoalveolar lavage fluids (BALF) and lung tissue were then assessed. Nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) signaling pathways in the lung were also evaluated. CLP/HMGB1 increased the wet to dry weight ratio and myeloperoxidase activity in lung, the number of total cells, neutrophils, and macrophages in the BALF, and inflammatory mediators in the BALF and lung tissues. Moreover, expression of HMGB1 and RAGE in lung tissues was increased after CLP. Ketamine inhibited all the above effects. It also inhibited the activation of IκB-α, NF-κB p65, and MAPK. Ketamine protects rats against HMGB1-RAGE activation in a rat model of sepsis-induced ALI. These effects may partially result from reductions in NF-κB and MAPK.

Li K ，Yang J ，Han X 《-》