Galantamine protects against lipopolysaccharide-induced acute lung injury in rats

Lipopolysaccharide (LPS)-induced endotoxemia triggers the secretion of proinflammatory cytokines and can cause acute lung injury (ALI). The high mobility group box 1 (HMGB1) protein plays an important role as a late mediator of sepsis and ALI. Galantamine (GAL) is a central acetylcholinesterase inhibitor that inhibits the expression of HMGB1. This study evaluated the effects of GAL by measuring levels of inflammatory mediators and observing histopathological features associated with LPS-induced ALI. Sixty 8-10 week old male Sprague-Dawley rats (200-240 g) were randomized into three groups as follows: control group, LPS group (7.5 mg/kg LPS), and LPS+GAL group (5 mg/kg GAL before LPS administration). Histopathological examination of lung specimens obtained 12 h after LPS administration was performed to analyze changes in wet-to-dry (W/D) weight ratio, myeloperoxidase (MPO) activity, and HMGB1 expression level. Additionally, plasma concentrations of tumor necrosis factor-α, interleukin-6, and HMGB1 were measured using an enzyme-linked immunosorbent assay at 0 (baseline), 3, 6, 9, and 12 h after LPS administration. Mortality in the three groups was recorded at 72 h. LPS-induced ALI was characterized by distortion of pulmonary architecture and elevation of MPO activity, W/D weight ratio, and levels of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-6, and HMGB1. Pretreatment with GAL significantly reduced the LPS-induced lung pathological changes, W/D weight ratio, levels of pro-inflammatory cytokines and MPO activity (ANOVA). Moreover, GAL treatment significantly decreased the mortality rate (ANOVA). In conclusion, we demonstrated that GAL exerted a protective effect on LPS-induced ALI in rats.     

Suppression of MAPK and NF-κB Pathways by Limonene Contributes to Attenuation of Lipopolysaccharide-Induced Inflammatory Responses in Acute Lung Injury

The present study aimed to investigate the protective role of limonene in lipopolysaccharide (LPS)-induced acute lung injury (ALI). ALI was induced in mice by intratracheal instillation of LPS (0.5 mg/kg), and limonene (25, 50, and 75 mg/kg) was injected intraperitoneally 1 h prior to LPS administration. After 12 h, bronchoalveolar lavage fluid (BALF) and lung tissue were collected. Limonene pretreatment at doses of 25, 50, and 75 mg/kg decreased LPS-induced evident lung histopathological changes, lung wet-to-dry weight ratio, and lung myeloperoxidase activity. In addition, pretreatment with limonene inhibited inflammatory cells and proinflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interleukin-6 in BALF. Furthermore, we demonstrated that limonene blocked the phosphorylation of IκBα, nuclear factor-κB (NF-κB) p65, p38 mitogen-activated protein kinase (MAPK), c-Jun NH2-terminal kinase, and extracellular signal-regulated kinase in LPS-induced ALI. The results presented here suggest that the protective mechanism of limonene may be attributed partly to decreased production of proinflammatory cytokines through the inhibition of NF-κB and MAPK activation.     

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

High-mobility group box 1 (HMGB1) plays a key role in the development of acute lung injury (ALI). Propofol, a general anesthetic with anti-inflammatory properties, has been suggested to be able to modulate lipopolysaccharide (LPS)-induced ALI. In this study, we investigated the effects of propofol on the expression of HMGB1 in a rat model of LPS-induced ALI. Rats underwent intraperitoneal injection of LPS to mimic sepsis-induced ALI. Propofol bolus (1, 5, or 10 mg/kg) was infused continuously 30 min after LPS administration, followed by infusion at 5 mg/(kg?·?h) through the left femoral vein cannula. LPS increased wet to dry weight ratio and myeloperoxidase activity in lung tissues and caused the elevation of total protein and cells, neutrophils, macrophages, and neutrophils in bronchoalveolar lavage fluid (BALF). Moreover, HMGB1 and other cytokine levels were increased in BALF and lung tissues and pathological changes of lung tissues were excessively aggravated in rats after LPS administration. Propofol inhibited all the above effects. It also inhibited LPS-induced toll-like receptor (TLR)2/4 protein upexpression and NF-κB activation in lung tissues and human alveolar epithelial cells. Propofol protects rats and human alveolar epithelial cells against HMGB1 expression in a rat model of LPS-induced ALI. These effects may partially result from reductions in TLR2/4 and NF-κB activation.     

高迁移率族蛋白1对内毒素急性肺损伤大鼠中性粒细胞凋亡改变的影响

目的 观察体外高迁移率族蛋白1（HMGB1）对内毒素急性肺损伤（ALI）大鼠中性粒细胞（PMN）凋亡改变的影响，以探讨HMGB1在ALI发病机制中的作用。方法 脂多糖注射复制大鼠急性肺损伤模型，在LPS致伤后不同时相点（有或无正丁酸钠干预时）获取肺组织、外周血中性粒细胞（PMN）、支气管肺泡灌洗液（BALF）。RT-PCR检测肺组织HMGB1 mRNA表达，流式细胞术（FCM）、Giemsa染色及TUNEL法检测PMN的凋亡改变。结果 与对照组比较，LPS急性肺损伤大鼠PMN凋亡率逐渐减低，鼠BALF中PMN凋亡开始时间及无存活细胞时间明显延长；LPS致伤后6-24h肺组织HMGB1 mRNA表达明显增高。正丁酸钠（SB）处理组动物肺组织于伤后6、12h肺组织HMGB1 mRNA表达均显著抑制，与LPS组比较，差异有显著性意义（P〈0．05）；形态学检查显示，LPS致伤后大鼠肺组织出现水肿及明显的病理变化，SB干预可减轻肺损伤的严重程度。致伤后肺损伤程度与肺组织HMGB1表达水平及PMN凋亡改变有关。结论 LPS致伤后，鼠肺HMGB1 mRNA高表达发生较晚，但持续较长时间；SB处理可削弱LPS诱导的PMN凋亡延迟及抑制，下调肺组织HMGB1 mRNA表达。HMGB1可能参与内毒素急性肺损伤时PMN的凋亡延迟及抑制效应。     

Vagal Efferent Fiber Stimulation Ameliorates Pulmonary Microvascular Endothelial Cell Injury by Downregulating Inflammatory Responses

Electrical stimulation of the vagus nerve may have positive effects on many inflammatory diseases. This study determined the beneficial effects of vagus nerve stimulation and the mechanisms by which it attenuates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Rats were intraperitoneally injected with 10 mg/kg LPS to induce ALI. The results showed that vagus nerve stimulation could improve lung injury, as evidenced by remarkable reductions in lung edema (wet-to-dry weight ratio), neutrophil infiltration (myeloperoxidase activity), and pulmonary permeability [total number of cells and protein concentrations in bronchoalveolar lavage fluid (BALF)]. In addition, vagus nerve stimulation not only decreased the expressions of Src-suppressed C kinase substrate and E-selectin proteins in lung tissue but also effectively attenuated the concentrations of the proinflammatory cytokines tumor necrosis factor-α, interleukin-1β, and interleukin-6 in BALF. These suggest that vagus nerve stimulation is a suitable treatment for LPS-induced ALI and indicate that it helps ameliorate pulmonary microvascular endothelial cell injury by downregulating inflammatory responses.     

1-磷酸鞘氨醇受体2抑制脂多糖诱导的急性肺损伤

 目的: 探讨1-磷酸鞘氨醇受体2(S1P2R)对脂多糖(LPS)诱导的急性肺损伤(ALI)中的作用及机制。方法: 野生小鼠和S1pr2^-/-小鼠经气管滴注LPS,建立急性肺损伤动物模型。LPS注射24 h时观察肺组织的病理改变,测定支气管肺泡灌洗液(BALF)中的蛋白浓度、总细胞数、中性粒细胞的比值及TNF-α、IL-6细胞因子的表达。为了观察S1P2R在肺损伤中的作用机制,LPS注射10 min前野生小鼠和S1pr2^-/-小鼠经尾静脉注射一氧化氮合酶抑制剂L-NAME,LPS注射12 h时,再观察肺的病理组织学变化以及BALF中的蛋白浓度,总细胞数及TNF-α、IL-6细胞因子表达的变化。结果: 与野生小鼠比较,S1pr2^-/-小鼠恶化LPS诱导的急性肺损伤,BALF中的蛋白浓度、总细胞数,中性粒细胞比值及炎症细胞因子表达显著增加。而L-NAME的预处理显著抑制在S1pr2^-/-小鼠LPS诱导加重的急性肺损伤。结论: S1P2R通过抑制NO合成,维持血管屏障,从而抑制急性肺损伤。     

Effects of HMGB1 on PMN apoptosis during LPS-induced acute lung injury

Objective

To observe the effects of intravenous injection of HMGB1 inhibitor sodium butyrate on changes in apoptosis of PMN during LPS-induced acute lung injury in rats and HMGB1 in vitro on human circulating PMN apoptosis, in order to clarify the role of HMGB1 in the pathogenesis of acute lung injury.

Methods

(1) LPS-induced acute lung injury rat model was developed by LPS infusion. At different time-points after LPS challenge in the presence or absence of sodium butyrate (SB), the rat tissue sample, peripheral blood PMNs and BALF were collected. RT-PCR was applied to examining rat lung tissue HMGB1 mRNA expression level, and Western blotting analysis was adopted to determine expression of rat lung tissue HMGB1 protein. PMN apoptotic changes were determined by flow cytometric (FCM) analysis, Giemsa staining and TdT-mediated dUTP nick end labeling (TUNEL) method. (2) Separated and purified human circulating PMN were coincubated for 24 h with different doses of HMGB1 (0, 10, 100, 1000 ng/ml, respectively) at 37 °C in 5% CO₂. PMN apoptosis rate was determined by flow cytometric (FCM) analysis and by TdT-mediated dUTP nick end labeling (TUNEL) method.

Results

(1) The percentage of apoptosis of PMN in rat model of LPS-induced ALI was gradually decreased as compared with that of normal control. The PMN apoptosis-initiation time and non-survival time in rat BALF prolonged significantly as compared with that of normal control. The injured rat lung tissue HMGB1 mRNA and protein expression was upregulated 6–24 h after LPS exposure; SB intervention significantly ameliorated the upregulation. In addition, the morphologic examination indicated that the edema severity and pathological changes of lung tissues were excessively aggravated in rats after LPS administration. By comparison, SB treatment diminished the severity of lung damage. Combined with lung HMGB1 expression level, the above changes indicate that the pathological changes of lung tissue were related to the injured lung HMGB1 expression, as well as apoptotic changes in PMN. (2) After coincubation of HMGB1 with human circulating PMNs, TUNEL and flow cytometry were performed. The study revealed that PMN apoptosis ratios was (40.53 ± 4.12) % in control group (PMNs + RPMI 1640 medium), (19.05 ± 2.44) % in LPS group (PMNs + RPMI 1640 medium + 10 μg/ml LPS), (40.52 ± 2.73) % in HMGB1-1 group (PMNs + RPMI 1640 medium + 10 ng/ml HMGB1), (34.89 ± 1.15) % in HMGB1-2 group (PMNs + RPMI 1640 medium + 100 ng/ml HMGB1), and (18.77 ± 3.02) % in HMGB1-3 group (PMNs + RPMI 1640 medium + 1 000 ng/ml HMGB1). There was statistical significance. Meanwhile, PMN TUNEL positive rate was (31.42 ± 4.40) %, (31.39 ± 3.80) %, (25.62 ± 2.46) %, and (17.98 ± 3.20) % in control group, HMGB1-1 group, HMGB1-2 group and HMGB1-3 group, respectively. The inhibitory effect was HMGB1 dose-depended as compared with that of control group.

Conclusion

After LPS challenge, high expression of rats' lung HMGB1 mRNA occurs at a later phase, but keeps for a long time. Sodium butyrate (SB) treatment attenuated LPS-induced PMN apoptosis delay and inhibition, and down-regulated HMGB1 mRNA expression of injured lung. HMGB1 in vitro inhibited human circulating PMN apoptosis markedly, and the inhibitory effect was HMGB1 dose-depended. The results demonstrated that HMGB1 may play an important role as a modulator in apoptotic changes in PMN during LPS-induced ALI. It concludes that HMGB1 may contribute to the development of PMN apoptotic changes during LPS-induced acute lung injury.     

Protective Effect of Isorhamnetin on Lipopolysaccharide-Induced Acute Lung Injury in Mice

Isorhamnetin has been reported to have anti-inflammatory, anti-oxidative, and anti-proliferative effects. The aim of this study was to investigate the protective effect of isorhamnetin on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice by inhibiting the expression of cyclooxygenase-2 (COX-2). The effects of isorhamnetin on LPS-induced lung pathological damage, wet/dry ratios and the total protein level in bronchoalveolar lavage fluid (BALF), inflammatory cytokine release, myeloperoxidase (MPO) and superoxide dismutase (SOD) activities, and malondialdehyde (MDA) level were examined. In addition, the COX-2 activation in lung tissues was detected by Western blot. Isorhamnetin pretreatment improved the mice survival rates. Moreover, isorhamnetin pretreatment significantly attenuated edema and the pathological changes in the lung and inhibited protein extravasation in BALF. Isorhamnetin also significantly decreased the levels of inflammatory cytokines in BALF. In addition, isorhamnetin markedly prevented LPS-induced oxidative stress. Furthermore, isorhamnetin pretreatment significantly suppressed LPS-induced activation of COX-2. Isorhamnetin has been demonstrated to protect mice from LPS-induced ALI by inhibiting the expression of COX-2.     

Ketamine effect on HMGB1 and TLR4 expression in rats with acute lung injury

Acute lung injury (ALI) is a common emergency and severe case in clinic. High mobility group protein box 1 (HMGB1) can be treated as a new anti-inflammatory treatment target. Toll-like receptor 4 (TLR4) is an important receptor of HMGB1. Ketamine is a widely used intravenous anesthetic with good anti-inflammatory and immune regulating function. Whether it can protect ALI through inhibiting HMGB1 and TLR4 expression in lung tissue still needs further investigation. Male SD rats were randomly divided into control, lipopolysaccharide (LPS) group and ketamine intervention group with 15 rats in each group. The rats were euthanatized at 24 h after modeling and the bronchoalveolar lavage fluid (BALF) was collected for HMGB1 and TLR4 level detection. Western Blot was applied to analyze HMGB1 and TLR4 protein expression in the lung tissue. HMGB1 and TLR4 concentration in BALF were 5.369 ± 1.564 ng/ml and 43.980 ± 7.524 pg/ml in the control, respectively. They were 12.358 ± 4.681 ng/ml and 102.538 ± 8.412 pg/ml in LPS group, and 7.399 ± 2.346 ng/ml and 87.208 ± 7.558 pg/ml in ketamine intervention group, respectively. Their levels increased significantly in LPS group and down-regulated after ketamine intervention. HMGB1 and TLR4 protein expression in lung tissue elevated obviously in LPS group, and decreased after ketamine treatment. HMGB1 and TLR4 protein level showed positive correlation in lung tissue (r = 0.921, P < 0.001). Ketamine can inhibit HMGB1 and TLR4 expression in ALI, and alleviate LPS induced rat lung injury.     

白藜芦醇通过激活SGK1上调急性肺损伤小鼠肺泡上皮钠离子通道的表达

目的探讨白藜芦醇(resveratrol)对急性肺损伤(ALI)小鼠肺泡上皮钠离子通道(ENaC)的作用及可能机制。方法将小鼠随机分为对照(control)组、LPS组、RES组和PP242组,每组6只。苏木精-伊红(HE)染色观察肺组织病理;BCA法测肺泡灌洗液(BALF)中蛋白含量,酶联免疫吸附实验(ELISA)检测炎性因子水平;流式细胞计量术检测BALF中性粒细胞比例;Western blot检测肺组织α-ENaC蛋白表达和SGK1磷酸化水平,实时荧光定量PCR(qPCR)检测肺组织α-ENaC mRNA转录水平。结果 1)与对照组相比,LPS组肺组织损伤明显,BALF中性粒细胞比例、蛋白含量和炎性因子水平明显升高(P0.05),肺组织α-ENaC表达和SGK1磷酸化水平显著下调(P0.05);2)与LPS组相比,RES组肺损伤明显减轻,BALF中性粒细胞比例、蛋白含量和炎性因子水平明显降低(P0.05),伴α-ENaC表达和SGK1磷酸化水平显著上调(P0.05);3)与RES组相比,PP242组肺损伤明显加重,BALF中性粒细胞比例、蛋白含量和炎性因子水平明显升高(P0.05),同时伴α-ENaC表达和SGK1磷酸化水平显著下调(P0.05)。结论 SGK1介导的α-ENaC上调机制参与了RES对ALI的保护作用。     

Protective effects of salidroside from Rhodiola rosea on LPS-induced acute lung injury in mice

Salidroside is a major component extracted from Rhodiola rosea. In this study, we investigated protective effects of salidroside on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. In the mouse model, we found that pretreatment with a single 120?mg/kg dose of salidroside prior to the administration of intratracheal LPS induced a significant decrease in the W/D ratio and mouse myeloperoxidase activity of lung, reduction protein concentration, the number of total cells, neutrophils and macrophages in the bronchoalveolar lavage fluid. In addition, salidroside also inhibited the production of several inflammatory cytokines, including tumor necrosis factor-α, interleukin-6 (IL-6) and IL-1β, and the NF-κB DNA-binding activation after LPS challenge. These results indicated that salidroside possess a protective effect on LPS-induced ALI in mice.     

藤黄酸减轻脂多糖诱导的小鼠急性肺损伤

目的探讨藤黄酸(GA)对脂多糖(LPS)所致小鼠急性肺损伤的保护作用及其机制。方法采用尾静脉注射LPS(4 mg/kg)建立小鼠急性肺损伤模型。实验将小鼠随机分为对照组(control组)、模型组(model组)、藤黄酸组(GA组)和藤黄酸预处理组(GA+LPS组),6 h后测定肺湿/干重比值(W/D);检测髓过氧化物酶(MPO)活性;检测肺泡灌洗液(BALF)中蛋白含量和白细胞计数;ELISA检测肺匀浆中白介素-1β(IL-1β)和肿瘤坏死因子-α(TNF-α)含量。结果模型组小鼠肺W/D、MPO活性、BALF中蛋白含量和白细胞数量均增加,肺组织IL-1β和TNF-α水平升高(均P0.01);藤黄酸预处理可减轻LPS引起的以上指标变化(均P0.05)。结论 GA可减轻LPS诱导的急性肺损伤,其机制可能与降低肺组织IL-1β和TNF-α的含量、抑制中性粒细胞在肺部的聚集和减轻肺部水肿相关。     

Inhibition of PKR ameliorates lipopolysaccharide-induced acute lung injury by suppressing NF-κB pathway in mice

Acute lung injury (ALI) is characterized by dramatic lung inflammation and alveolar epithelial cell death. Although protein kinase R (PKR) (double-stranded RNA-activated serine/threonine kinase) has been implicated in inflammatory response to bacterial cell wall components, whether it plays roles in lipopolysaccharide (LPS)-induced ALI remains unclear. This study was aimed to reveal whether and how PKR was involved in LPS-induced ALI pathology and the potential effects of its specific inhibitor, C16 (C₁₃H₈N₄OS). During the experiment, mice received C16 (100 or 500 ug/kg) intraperitoneally 1?h before intratracheal LPS instillation. Then, whole lung lavage was collected for analysis of total protein levels and proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6. The lungs were tested for Western blot, transferase-mediated dUTP nick-end labeling (TUNEL) stain and immunohistochemistry. Results showed that PKR phosphorylation increased significantly after LPS instillation. Furthermore, PKR specific inhibition attenuated LPS-induced lung injury (hematoxylin and eosin stain), reduced lung protein permeability (total protein levels in whole lung lavage) and suppressed proinflammatory cytokines (TNF-α, IL-1β and IL-6) and lung apoptosis (TUNEL stain and caspase3 activation). Moreover, mechanism-study showed that C16 significantly suppressed I kappa B kinase (IKK)/I kappa B alpha (IκBα)/NF-κB signaling pathway after LPS challenge. These findings suggested that PKR inhibition ameliorated LPS-induced lung inflammation and apoptosis in mice by suppressing NF-κB signaling pathway.     

Protective Effect of Amygdalin on LPS-Induced Acute Lung Injury by Inhibiting NF-κB and NLRP3 Signaling Pathways

The acute lung injury (ALI) is a leading cause of morbidity and mortality in critically ill patients. Amygdalin is derived from the bitter apricot kernel, an efficacious Chinese herbal medicine. Although amygdalin is used by many cancer patients as an antitumor agent, there is no report about the effect of amygdalin on acute lung injury. Here we explored the protective effect of amygdalin on ALI using lipopolysaccharide (LPS)-induced murine model by detecting the lung wet/dry ratio, the myeloperoxidase (MPO) in lung tissues, inflammatory cells in the bronchoalveolar lavage fluid (BALF), inflammatory cytokines production, as well as NLRP3 and NF-κB signaling pathways. The results showed that amygdalin significantly reduced LPS-induced infiltration of inflammatory cells and the production of TNF-α, IL-1β, and IL-6 in the BALF. The activity of MPO and lung wet/dry ratio were also attenuated by amygdalin. Furthermore, the western blotting analysis showed that amygdalin remarkably inhibited LPS-induced NF-κB and NLRP3 activation. These findings indicate that amygdalin has a protective effect on LPS-induced ALI in mice. The mechanism may be related to the inhibition of NF-κB and NLRP3 signaling pathways.     

亚精胺减轻脂多糖诱导的小鼠急性肺损伤

目的　观察亚精胺（spermidine）对脂多糖（LPS）诱导的急性肺损伤（ALI）的影响。 方法　采用5 mg/kg的LPS经气管滴注,建立ALI小鼠模型。用小动物呼吸机检测亚精胺对ALI小鼠呼吸功能的影响;观察亚精胺对ALI小鼠肺组织形态变化的影响;检测ALI小鼠支气管肺泡灌洗液（BALF）中总蛋白、总细胞数及中性粒细胞数目,并检测髓过氧化物酶（MPO）的水平;qPCR检测ALI小鼠肺组织中TREM-1 mRNA的表达;ELISA检测ALI小鼠BALF中sTREM-1的蛋白水平。 结果　亚精胺可改善ALI小鼠的呼吸功能;减轻LPS诱导的肺部病理损伤;减少蛋白渗出和中性粒细胞浸润;降低ALI小鼠肺内炎症放大受体TREM-1的表达。 结论　亚精胺能减少炎症细胞浸润,抑制炎症因子表达,从而减轻LPS诱导的ALI,其机制可能与亚精胺可抑制ALI小鼠肺组织TREM-1表达有关。     

TNFR-Fc减轻LPS所致小鼠ALI炎症反应损伤

目的: 评价肿瘤坏死因子受体-Fc融合蛋白(TNFR-Fc)能否有效下调炎症反应而减轻急性肺损伤(ALI)小鼠的肺组织破坏。方法: 小鼠随机分为脂多糖(LPS)组、TNFR-Fc+LPS组和对照组。气管内滴入LPS复制ALI小鼠模型,TNFR-Fc组在滴入LPS前24 h腹膜腔注射TNFR-Fc (0.4 mg/kg),在滴入LPS后2 h收集标本,检测肺湿/干重、肺泡蛋白含量与肺组织病理评分;ELISA法检测血清TNF-α浓度及检测肺泡灌洗液与血清IL-1β、IL-6、IL-10与IFN-γ浓度。结果: TNFR-Fc显著降低血清TNF-α浓度(P＜0.05),轻度降低肺湿/干重比例,显著降低BALF蛋白浓度(P＜0.05),显著降低ALI评分数值(P＜0.05)。TNFR-Fc显著降低致炎症细胞因子IL-6在BALF(P＜0.05)与血清(P＜0.05)中的浓度,轻度提高BALF中IL-10浓度(P＞0.05),但其差异不显著,亦能显著提高血清IL-10浓度(P＜0.05)。IL-1β与IFN-γ水平处理前后变化不显著。结论: TNFR-Fc中和ALI中过度表达的TNF-α,下调以IL-6为代表的炎症反应,减轻ALI的肺组织破坏。     

Preventive Effects of Valnemulin on Lipopolysaccharide-Induced Acute Lung Injury in Mice

Valnemulin reportedly regulates inflammatory responses in addition to its in vitro antibacterial activity. In this study, we established a mouse model of lipopolysaccharide (LPS)-induced inflammatory lung injury and investigated the effect of valnemulin (100 mg/kg) on acute lung injury (ALI) 8 h after LPS challenge. We prepared bronchoalveolar lavage fluid (BALF) for measuring protein concentrations, cytokine levels, and superoxidase dismutase (SOD) activity, and collected lungs for assaying wet-to-dry weight (W/D) ratios, myeloperoxidase (MPO) activity, cytokine mRNA expression, and histological change. We found that the pre-administration of valnemulin significantly decreases the W/D ratio of lungs, protein concentrations, and the number of total cells, neutrophils, macrophages, and leukomonocytes, and histologic analysis indicates that valnemulin significantly attenuates tissue injury. Furthermore, valnemulin significantly increases LPS-induced SOD activity in BALF and decreases lung MPO activity as well. In addition, valnemulin also inhibits the production of tumor necrosis factor-α, interleukin-6, and interleukin-1β, which is consistent with mRNA expression in lung. The results showed that valnemulin had a protective effect on LPS-induced ALI in mice.     

Treatment of Low Molecular Weight Heparin Inhibits Systemic Inflammation and Prevents Endotoxin-Induced Acute Lung Injury in Rats

To determine whether low molecular weight heparin (LMWH) is able to reduce pulmonary inflammation and improve the survival in rats with endotoxin-induced acute lung injury (ALI). Rat ALI model was reproduced by injection of lipopolysaccharide (LPS) into tail vein. Rats were divided randomly into three groups: control group, ALI group, LMWH-treated group. Blood was collected and lung tissue was harvested at the designated time points for analysis. The lung specimens were harvested for morphological studies, streptavidin-peroxidase immunohistochemistry examination. Lung tissue edema was evaluated by tissue water content. The levels of lung tissue myeloperoxidase (MPO) were determined. Meanwhile, the nuclear factor-kappa B (NF-κB) activation, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) levels and high mobility group box 1 (HMGB1) and intercellular adhesion molecule-1 (ICAM-1) protein levels in the lung were studied. In survival studies, a separate group of rats were treated with LMWH or sterile saline after LPS administration. Then, the mortality was recorded. Treatment with LMWH after ALI was associated with a reduction in the severity of LPS-induced lung injury. Treatment with LMWH significantly decreased the expression of TNF-α, IL-1β, HMGB1 and ICAM-1 in the lung of ALI rats. Similarly, treatment with LMWH dramatically diminished LPS-induced neutrophil sequestration and markedly reduced the enhanced lung permeability. In the present study, LMWH administration inhibited the nuclear translocation of NF-κB in the lung. Survival was significantly higher among the LMWH-treated group compared with the ALI group. These data suggest that LMWH attenuates inflammation and prevents lethality in endotoxemic rats.     

黑木耳多糖对内毒素诱导急性肺损伤大鼠肺组织的保护作用

目的:探讨黑木耳多糖对LPS诱导急性肺损伤大鼠肺组织的保护作用及其机制。方法:将健康SD大鼠随机分为对照组、LPS组、地塞米松组以及黑木耳多糖低、中、高浓度组,根据分组,分别给予生理盐水或不同浓度黑木耳多糖预防性灌胃7 d,第8天腹腔注射生理盐水或LPS(8 mg/kg),地塞米松组在给予LPS后腹腔注射地塞米松(3 mg/kg)。造模12 h后于腹主动脉取血,并制肺组织匀浆和肺泡灌洗液。检测支气管肺泡灌洗液中蛋白含量、肺湿/干重比、髓过氧化物酶(MPO)、总抗氧化能力(T-AOC)、总超氧化物歧化酶(T-SOD)、一氧化氮合酶(NOS)、丙二醛(MDA)等指标,做组织切片HE染色并进行肺损伤评分。结果:应用黑木耳多糖干预后,急性肺损伤大鼠支气管肺泡灌洗液中蛋白含量明显下降,肺湿/干重比值降低;大鼠肺组织中MPO、NOS活性及MDA含量较LPS组降低,T-AOC含量和T-SOD活性较之升高;肺组织病理改变减轻,肺损伤指数下降。结论:黑木耳多糖具有保护LPS损伤大鼠肺组织的作用,其机制可能与其抗氧化作用有关。     

Distinct roles of pattern recognition receptors CD14 and Toll-like receptor 4 in acute lung injury

Acute lung injury (ALI) induced by lipopolysaccharide (LPS) is a major cause of mortality among humans. ALI is characterized by microvascular protein leakage, neutrophil influx, and expression of proinflammatory mediators, followed by severe lung damage. LPS binding to its receptors is the crucial step in the causation of these multistep events. LPS binding and signaling involves CD14 and Toll-like receptor 4 (TLR4). However, the relative contributions of CD14 and TLR4 in the induction of ALI and their therapeutic potentials are not clear in vivo. Therefore, the aim of the present study was to compare the roles of CD14 and TLR4 in LPS-induced ALI to determine which of these molecules is the more critical target for attenuating ALI in a mouse model. Our results show that CD14 and TLR4 are necessary for low-dose (300-microg/ml) LPS-induced microvascular leakage, NF-kappaB activation, neutrophil influx, cytokine and chemokine (KC, macrophage inflammatory protein 2, tumor necrosis factor alpha, interleukin-6) expression, and subsequent lung damage. On the other hand, when a 10-fold-higher dose of LPS (3 mg/ml) was used, these responses were only partially dependent on CD14 and they were totally dependent on TLR4. The CD14-independent LPS response was dependent on CD11b. A TLR4 blocking antibody abolished microvascular leakage, neutrophil accumulation, cytokine responses, and lung pathology with a low dose of LPS but only attenuated the responses with a high dose of LPS. These data are the first to demonstrate that LPS-induced CD14-dependent and -independent (CD11b-dependent) signaling pathways in the lung are entirely dependent on TLR4 and that blocking TLR4 might be beneficial in lung diseases caused by LPS from gram-negative pathogens.