慢性乙醇摄取对急性肺损伤大鼠气道上皮细胞间连接蛋白occludin和E-cadherin及屏障功能的影响

目的 观察慢性乙醇摄取及内毒素处理对大鼠气道上皮屏障功能及紧密连接(TJ)特征性蛋白occludin和黏附连接(AJ)蛋白E-cadherin的影响.方法 将40只SD大鼠随机均分为对照组、慢性乙醇摄取组(乙醇组)、内毒素处理组(LPS组)、慢性乙醇摄取合并内毒素处理组(乙醇+LPS组).利用荧光示踪剂异硫氰酸荧光素标记的右旋糖酐(FD4)测定支气管肺泡上皮的通透性;免疫荧光共聚焦显微镜下观察大鼠气道上皮occludin和E-cadherin蛋白分布及表达;蛋白质免疫印迹法(Western blotting)和逆转录-聚合酶链反应(RT-PCR)测定肺组织中occludin和E-cadherin的蛋白及mRNA表达;并观察肺组织病理学改变.结果 乙醇组及LPS组支气管肺泡上皮通透性均较对照组明显增高(P均＜0.05);乙醇+LPS组支气管肺泡上皮的通透性进一步增高(P＜0.01).occludin和E-cadherin蛋白在对照组大鼠气道上皮呈连续、均匀的胞膜及胞质中表达;在乙醇组、LPS组胞膜呈部分断裂、不连续的表达,且胞膜和胞质的表达下降;在乙醇+LPS组的表达显著下降,且胞膜表达呈明显的断裂甚至消失.Western blotting和RT-PCR显示,乙醇组和LPS组肺组织中occludin和E-cadherin的蛋白及mRNA表达均较对照组明显下降(P均＜0.05);乙醇+LPS组中蛋白及mRNA表达下降最为明显,与其余各组比较差异均有统计学意义(P均＜0.01).结论 慢性乙醇摄取通过降低TJ蛋白occludin和AJ蛋白E-cadherin的蛋白及mRNA表达水平,并干扰各蛋白在胞膜上的定位,最终导致气道上皮屏障功能受损,加重内毒素诱导的急性肺损伤.     

谷氨酰胺对急性肺损伤大鼠肺泡上皮屏障功能的影响

目的:观察谷氨酰胺对急性肺损伤大鼠肺泡上皮屏障功能及紧密连接(TJ)特征性蛋白occludin和黏附连接蛋白E-cadherin的影响。方法:40只SD大鼠随机分为对照组、谷氨酰胺处理组(Gln组)、内毒素处理组(LPS组)、谷氨酰胺并内毒素处理组(Gln+LPS组)。测定支气管肺泡渗透性、运用免疫印迹测定和RT-PCR测定肺泡Ⅱ型上皮细胞中occludin和E-cadherin的蛋白及mRNA表达。结果:内毒素导致支气管肺泡上皮渗透性明显增高2倍左右(P<0.01);补充谷氨酰胺可以明显改善由内毒素处理引起的支气管肺泡上皮渗透性增高(P<0.05),但Gln+LPS组支气管肺泡渗透性仍较对照组及Gln组增高(P<0.05)。免疫印迹和RT-PCR显示在LPS组的occludin和E-cadherin蛋白和mRNA表达水平均较对照组及Gln组的低(P<0.01);在Gln+LPS组中occludin和E-cadherin的蛋白和mRNA表达水平较LPS组的高(P<0.05),而较对照组及Gln组的表达水平低(P<0.05)。结论:实验提示内毒素通过降低TJ分子occludin和E-cadherin的mRNA、蛋白表达水平导致肺泡上皮屏障功能受损,补充谷氨酰胺通过上调其mRNA、蛋白表达水平而对肺泡上皮屏障功能有保护作用。     

大黄对内毒素诱导致急性肺损伤的保护作用

目的：探讨内毒素在急性肺损伤（ＡＬＩ０中的作用机制及大黄,地塞米松对ＡＬＩ的保护作用。方法：在Ｗｉｓｔａｒ大鼠舌下静脉注射内毒素（ＬＰＳ）复制ＡＬＩ动物模型。动物分为４组：ＬＰＳ致伤组,对照组（生理盐水）,地塞米松治疗组,大黄治疗组。肉眼观察肺大体标本;普通光镜检查肺组织病理变化;电镜观察肺组织超微结构;测定ＡＬＩ的生物学指标;肺湿重与干重比,肺泡灌洗液中中性粒细胞比例和蛋白含量,肺泡通透指数和肺     

肺复张手法对急性肺损伤大鼠肺泡上皮细胞屏障功能的影响

目的 观察肺复张手法对急性肺损伤（ALI）大鼠肺泡上皮细胞屏障功能的影响。方法雄性清洁级SD大鼠48只，静脉注射脂多糖（LPS）复制ALI模型，随机分为对照组、ALI模型组（ALI组）、小潮气量（VT）通气组（LV组）和肺复张联合小VT通气组（SI组）。采用控制性肺膨胀（SI）实施肺复张手法。机械通气4h后，观察肺组织病理学改变；采用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法（TUNEL）检测肺泡上皮细胞凋亡情况；用重力法测定血管外肺水（EVLW）含量；用单核素示踪技术测定肺泡上皮细胞通透性改变；用逆转录-聚合酶链反应（RT—PCR）检测肺组织肺泡表面活性蛋白-C（SP—C）mRNA表达；用酶联免疫吸附法（ELISA）检测支气管肺泡灌洗液（BALF）中白细胞介素-6（IL-6）和IL-10浓度。结果 光镜下，SI组肺组织损伤程度轻于ALI组和LV组。LV组凋亡肺泡上皮细胞散在分布，SI组凋亡上皮细胞明显减少。与对照组相比，ALI组、LV组及SI组肺损伤评分和EVLW均显著升高；与ALI组比较，LV组和SI组肺损伤评分显著降低，SI组肺损伤评分及EVLW显著低于LV组（P均〈0．05）。与对照组相比，ALI组、LV组及SI组肺组织SP—C mRNA表达均显著降低，而SI组肺组织SP—C mRNA表达显著高于LV组（P〈0．05），但与ALI组比较差异无显著性。ALI组、LV组和SI组BALF中IL-6和IL-10浓度均显著高于对照组（P均〈0．05），SI组IL-6浓度显著低于LV组（P〈0．05）。各组肺泡上皮细胞通透性间比较差异均无显著性。结论 肺复张手法可以减轻ALI肺组织病理损伤，增加肺泡上皮细胞SP—C mRNA的合成，下调肺部炎症反应，改善肺泡上皮细胞屏障功能。     

不同液体治疗对急性肺损伤大鼠肺泡上皮细胞屏障功能的影响

目的 观察不同液体治疗对急性肺损伤(ALI)大鼠肺泡上皮细胞屏障功能的影响.方法 ①与对照组比较,LPS组、NS组肺损伤评分明显升高(P均<0.05);与NS组比较,5%人血白蛋白(ALB)组、6%羟乙基淀粉130/0.4(HES)组评分均明显降低(P均<0.05),4%琥珀酰明胶(GEL)组无明显差异(P>0.05),且后3组间比较差异也无统计学意义.②与对照组比较,LPS组、NS组肺W/D比值明显升高(P均<0.05);ALB组、HES组、GEL组均较NS组明显下降(P均<0.05),3组间比较无差异.③LPS组、NS组肺泡上皮通透性均较对照组明显升高(P均<0.05);ALB组、HES组、GEL组肺泡上皮通透性均较NS组明显降低,且后两组明显低于ALB组(P均<0.05),但仍高于对照组.④LPS组、NS组、ALB组、GEL组肺组织SP-C mRNA表达较对照组、HES组明显下降(P均<0.05);而HES组和对照组间无明显差异(P>0.05).⑤各组肺泡上皮细胞凋亡指数(AI)明显高于对照组(P均<0.05);ALB组、HES组AI较NS组明显下降(P均<0.05),但与GEL组无明显差异(P均>0.05).结论 胶体液较NS更能改善ALI大鼠肺泡上皮通透性,保护上皮细胞屏障功能.     

Increased iNOS activity is essential for intestinal epithelial tight junction dysfunction in endotoxemic mice

We tested the hypothesis that increased production of nitric oxide (NO.) associated with lipopolysaccharide (LPS)-induced systemic inflammation leads to functionally significant alterations in the expression and/or targeting of key tight junction (TJ) proteins in ileal and colonic epithelium. Wild-type or inducible NO. synthase (iNOS) knockout male C57B1/6J mice were injected intraperitoneally with 2 mg/kg Escherichia coli O111:B4 LPS. iNOS was inhibited using intraperitoneal L-N(6)-(1-iminoethyl)lysine (L-NIL; 5 mg/kg). Immunoblotting of total protein and NP-40 insoluble proteins revealed decreased expression and decreased TJ localization, respectively, of the TJ proteins, zonula occludens (ZO)-1, ZO-2, ZO-3, and/or occludin in ileal mucosa and colonic mucosa (total protein only) after injection of C57B1/6J mice with LPS. Immunohistochemistry showed deranged distribution of ZO-1 and occludin in both tissues from endotoxemic mice. Endotoxemia was associated with evidence of gut epithelial barrier dysfunction evidenced by increased ileal mucosal permeability to fluorescein isothiocyanate-dextran (Mr=4 kDa) and increased bacterial translocation to mesenteric lymph nodes. Pharmacologic inhibition of iNOS activity using L-NIL or genetic ablation of the iNOS gene ameliorated LPS-induced changes in TJ protein expression and gut mucosal barrier function. These results support the view that at least one mechanism contributing to the pathogenesis of gastrointestinal epithelial dysfunction secondary to systemic inflammation is increased iNOS-dependent NO. production leading to altered expression and localization of key TJ proteins.     

Differential responses of the endothelial and epithelial barriers of the lung in sheep to Escherichia coli endotoxin.

Although intravenous Escherichia coli endotoxin has been used extensively in experimental studies to increase lung endothelial permeability, the effect of E. coli endotoxin on lung epithelial permeability has not been well studied. To examine this issue in sheep, bidirectional movement of protein across the lung epithelial barrier was studied by labeling the vascular space with 131I-albumin and by instilling 3 ml/kg of an isosmolar protein solution with 125I-albumin into the alveoli. E. coli endotoxin was administered according to one of three protocols: intravenous alone (5-500 micrograms/kg), intravenous (5 micrograms/kg) plus low-dose alveolar endotoxin (10 micrograms/kg), and high-dose alveolar endotoxin alone (50-100 micrograms/kg). Alveolar liquid clearance was estimated based on the concentration of the instilled native protein. Sheep were studied for either 4 or 24 h. Although intravenous E. coli endotoxin produced a marked increase in transvascular protein flux and interstitial pulmonary edema, there was no effect on the clearance of either the vascular (131I-albumin) or the alveolar (125I-albumin) protein tracer across the epithelial barrier. High-dose alveolar E. coli endotoxin caused a 10-fold increase in the number of leukocytes, particularly neutrophils, that accumulated in the air spaces. In spite of the marked chemotactic effect of alveolar endotoxin, there was no change in the permeability of the epithelial barrier to the vascular or alveolar protein tracers. Also, alveolar epithelial liquid clearance was normal. Morphologic studies confirmed that the alveolar epithelial barrier was not injured by either intravenous or alveolar E. coli endotoxin. Thus, the alveolar epithelium in sheep is significantly more resistant than the lung endothelium to the injurious effects of E. coli endotoxin.     

Der p 1 facilitates transepithelial allergen delivery by disruption of tight junctions

House dust mite (HDM) allergens are important factors in the increasing prevalence of asthma. The lung epithelium forms a barrier that allergens must cross before they can cause sensitization. However, the mechanisms involved are unknown. Here we show that the cysteine proteinase allergen Der p 1 from fecal pellets of the HDM Dermatophagoides pteronyssinus causes disruption of intercellular tight junctions (TJs), which are the principal components of the epithelial paracellular permeability barrier. In confluent airway epithelial cells, Der p 1 led to cleavage of the TJ adhesion protein occludin. Cleavage was attenuated by antipain, but not by inhibitors of serine, aspartic, or matrix metalloproteinases. Putative Der p 1 cleavage sites were found in peptides from an extracellular domain of occludin and in the TJ adhesion protein claudin-1. TJ breakdown nonspecifically increased epithelial permeability, allowing Der p 1 to cross the epithelial barrier. Thus, transepithelial movement of Der p 1 to dendritic antigen-presenting cells via the paracellular pathway may be promoted by the allergen's own proteolytic activity. These results suggest that opening of TJs by environmental proteinases may be the initial step in the development of asthma to a variety of allergens.     

The primary defect in experimental ileitis originates from a nonhematopoietic source

The initiating etiologic factor in Crohn's disease (CD) remains unclear. SAMP1/YitFc (SAMP) mice develop chronic ileitis similar to human CD. We used bone marrow chimeras to determine if SAMP ileitis results from a primary immunological defect or from dysregulated mucosal immunity secondary to intrinsic, nonhematopoietic (e.g., epithelial) dysfunction. SAMP mice receiving wild-type (AKR) BM developed severe ileitis, whereas SAMP BM did not confer ileitis to WT recipients. WT lymphocytes from reconstituted SAMP mice resembled native SAMP populations in regard to surface phenotype and cytokine production. Ilea from native SAMP mice and SAMP recipients of wild-type BM displayed decreased epithelial barrier resistance ex vivo and increased epithelial permeability in vivo compared to native WT mice and AKR recipients of SAMP BM. This permeability defect preceded the development of ileal inflammation, was present in the absence of commensal bacteria, and was accompanied by altered ileal mRNA expression of the tight junction proteins claudin-2 and occludin. Our results provide evidence that the primary defect conferring ileitis in SAMP mice originates from a nonhematopoietic source. Generation of pathogenic lymphocytes is a consequence of this defect and does not reflect intrinsic proinflammatory leukocyte properties. Decreased barrier function suggests that defects in the epithelium may represent the primary source of SAMP ileitis susceptibility.     

Increased intestinal endotoxin absorption during enteric nematode but not protozoal infections through a mast cell-mediated mechanism

It is known that hypersensitivity reactions in the gastrointestinal tract, which are primarily mediated by mast cells, are associated with a secretory response of the epithelium and often increased permeability to macromolecules. Studies to date have not examined the effects of hyperpermeability on the absorption of toxic substances normally present in the intestinal lumen such as bacterial LPS. In the present study, we observed that Strongyloides venezuelensis infection in mice decreases the mRNA expression of intestinal epithelial cell junctional molecules (occludin and zonula occludens 1) and increases portal endotoxin levels 4 h after intragastric administration of LPS (20 mg/kg body weight). Furthermore, an increase in the flux of immunoglobulin G into the intestinal lumen was observed 10 days postinfection (PI). An increased rate of LPS absorption was also seen in mice infected with Nippostrongylus brasiliensis on day 14 PI and rats concurrently infected with S. venezuelensis and N. brasiliensis on day 20 PI. On the other hand, infection with Eimeria vermiformis and Eimeria pragensis was not observed to enhance LPS absorption 4 h after intragastric administration of LPS (20 mg/kg body weight), although E. vermiformis infection did inhibit the epithelial cell mRNA expression of zonula occludens 1, but not occludin, on day 9 PI, resulting in a reduced immunoglobulin G flux than that produced by S. venezuelensis infection. Our results suggest that mastocytosis accompanying intestinal nematode infection increases the intestinal absorption of LPS into the portal circulation by suppressing the expression of tight junction molecules.     

NO和iNOS在内毒素诱导的大鼠急性肺损伤的作用及大黄对其影响

目的 主要探讨一氧化氮（ＮＯ）和诱导型一氧化氮合酶（ｉＮＯＳ）在内毒素（ＬＰＳ）诱导的大鼠急性肺损伤（ＡＬＩ）的作用机制及大黄对其影响。方法 在雄性Ｗｉｓｔａｒ大鼠利用舌下静脉注射ＬＰＳ复制ＡＬＩ动物模型,动物分为４组：ＬＰＳ组,对照组,大黄治疗组,地塞米松组。观察大体标本,组织病理以及生物学标志：肺湿／干重比,肺泡灌洗液中性粒细胞比,蛋白含量,肺血管通透性和肺泡通透性指数。同时测定血浆ＮＯ和肺组     

Burn-induced gut barrier injury is attenuated by phosphodiesterase inhibition: effects on tight junction structural proteins

Loss of intestinal barrier function after burn injury allows movement of intraluminal contents across the mucosa, which can lead to the development of distant organ injury and multiple organ failure. Tight junction function is highly regulated by membrane-associated proteins including occludin and zonula occludens protein 1 (ZO-1), which can be modulated by systemic inflammation. We hypothesized that (1) burn injury leads to gut barrier injury, and (2) phosphodiesterase inhibition will attenuate these burn-induced changes. Male balb/c mice undergoing a 30% steam burn were randomized to resuscitation with normal saline or normal saline + pentoxifylline (PTX; 12.5 mg/kg). Intestinal injury was assessed by histological diagnosis and TNF-alpha levels using enzyme-linked immunosorbent assay. Intestinal permeability was assessed by measuring the plasma concentration of fluorescein isothiocyanate-dextran after intraluminal injection in the distal ileum. Occludin and ZO-1 levels were analyzed by immunoblotting and immunohistochemistry. Thirty percent total body surface area (TBSA) burn results in a significant increase in intestinal permeability. Treatment with PTX after burn attenuates intestinal permeability to sham levels. Burn injury resulted in a marked decrease in the levels of tight junction proteins occludin and ZO-1 at 6 and 24 h. The use of PTX after burn significantly decreases the breakdown of occludin and ZO-1. Pentoxifylline also attenuates the burn-induced increase in plasma and intestinal TNF-alpha. Confocal microscopy demonstrates that PTX attenuates the burn-induced reorganization of occludin and ZO-1 away from the tight junction. Pentoxifylline attenuates burn-induced intestinal permeability and decreases the breakdown and reorganization of intestinal occludin and ZO-1. Therefore, phosphodiesterase inhibition may be a useful adjunct strategy in the attenuation of burn-induced gut barrier injury.     

Levobupivacaine attenuates lipopolysaccharide‐induced acute lung injury

Levobupivacaine (LB), a kind of local anesthetic, possesses anti‐inflammatory properties. High‐mobility group box 1 (HMGB1), a nuclear DNA‐binding protein, plays a key role in the development of acute lung injury (ALI). The aim of this study was to investigate whether LB attenuates ALI by the inhibition of HMGB1 expression and to investigate the molecular mechanisms. ALI in male rats was induced by an intratracheal instillation of LPS (5 mg/kg), and male rats received mini‐osmotic pumps containing LB 30 min after LPS exposure. A549 alveolar epithelial cells were incubated with LPS in the presence or absence of LB. An enzyme‐linked immunosorbent assay was used to detect the levels of inflammatory cytokines. Western blotting was used to detect the changes in the expression of toll‐like receptor 2/4 (TLR2/4) and the activation of NF‐κB. The results showed that LB significantly protected animals from LPS‐induced ALI as evidenced by a decrease in the ratio of lung wet to dry weight, total cells, neutrophils, macrophages, and myeloperoxidase activity, associated with a reduced lung histological damage. We also found that LB post‐treatment markedly inhibited the release of HMGB1 and other pro‐inflammatory cytokines. Furthermore, LB significantly inhibited LPS‐induced TLR2/4 protein overexpression and NF‐κB activation in the lung tissues and in LPS‐stimulated A549 alveolar epithelial cells in vitro. These data indicate that LB attenuated LPS‐induced ALI by the inhibition of HMGB1 expression in rats. These benefits were associated with the inhibition of TLR2/4‐NF‐κB pathway by LB.     

Chronic ethanol ingestion impairs alveolar type II cell glutathione homeostasis and function and predisposes to endotoxin-mediated acute edematous lung injury in rats.

Chronic alcohol abuse increases the incidence and mortality of the acute respiratory distress syndrome (ARDS) in septic patients. To examine a potential mechanism, we hypothesized that ethanol ingestion predisposes to sepsis-mediated acute lung injury by decreasing alveolar type II cell glutathione homeostasis and function. Lungs isolated from rats fed ethanol (20% in water for >/= 3 wk), compared with lungs from control-fed rats, had greater (P < 0. 05) edematous injury (reflected by nonhydrostatic weight gain) after endotoxin (2 mg/kg intraperitoneally) and subsequent perfusion ex vivo with n-formylmethionylleucylphenylalanine (fMLP, 10(-7) M). Ethanol ingestion decreased (P < 0.05) glutathione levels in the plasma, lung tissue, and lung lavage fluid, and increased (P < 0.05) oxidized glutathione levels in the lung lavage fluid. Furthermore, ethanol ingestion decreased type II cell glutathione content by 95% (P < 0.05), decreased (P < 0.05) type II cell surfactant synthesis and secretion, and decreased (P < 0.05) type II cell viability, in vitro. Finally, treatment with the glutathione precursors S-adenosyl-L-methionine and N-acetylcysteine in the final week of ethanol ingestion significantly reduced lung edema during perfusion ex vivo. We conclude that ethanol ingestion in rats alters alveolar type II cell glutathione levels and function, thereby predisposing the lung to acute edematous injury after endotoxemia. We speculate that chronic alcohol abuse in humans predisposes to ARDS through similar mechanisms.     

角化细胞生长因子对内毒素诱导急性肺损伤的保护作用

目的 初步研究角化细胞生长因子(KGF)对脂多糖(LPS)诱导大鼠急性肺损伤(ALI)的保护作用及可能的机制.方法 将36只SD大鼠按随机数字表法分为3组,每组12只.模型组尾静脉注射LPS 5 mg/kg建立ALI动物模型.对照组和KGF组注射等量生理盐水.KGF组在注射LPS后气道给予KGF 5 mg/kg.8 h后处死各组大鼠观察肺组织病理改变,并测量肺血管通透性、肺上皮细胞通透性、肺湿/干重(W/D)比值以及Ⅱ型肺泡上皮细胞(ATⅡ)增殖、修复功能改变.结果 光镜下观察显示KGF可有效减轻LPS所致ALI的肺组织病理改变,表现为肺血管充血、水肿减轻,几乎无炎性细胞浸润.与模型组比较,KGF组肺血管通透性[(0.026±0.049)%比(0.087±0.027)%]和肺泡上皮通透性[(0.692±0.017)%比(0.931±0.029)%]及W/D比值(4.778±0.243比6.869±0.153)均明显降低(P<0.05或P<0.01),ATⅡ细胞增殖及修复功能则明显提高[ATⅡ数量(个):6.083±1.781比4.666±1.923,损伤面积(mm2):2.946±0.453比6.181±0.975,P<0.05和P<0.01].结论 KGF可减轻LPS所致ALI,其机制可能是通过增强ATⅡ细胞的增殖及修复能力从而起到有效的保护作用.     

Massive alveolar thrombin activation in Pseudomonas aeruginosa-induced acute lung injury

In acute lung injury (ALI), a coagulation/fibrinolysis imbalance leads to fibrin deposition, persistence of which contributes to fibrotic evolution. Our study evaluated the effects of early inhibition of coagulation in Pseudomonas aeruginosa (Pa)-induced ALI through the use of recombinant human antithrombin (rhAT). The study was conducted in vivo on a murine model of Pa-induced ALI. Intravenous rhAT was administered simultaneously with intratracheal Pa. Four experimental groups were compared: CTR, intratracheal saline (0.5 mL/kg)/intravenous saline (1 mL); PNP, intratracheal Pa (0.5 mL/kg of 2 x 10(9) cfu)/intravenous saline; AT, intratracheal saline/intravenous rhAT (500 IU/kg); ATPNP, intratracheal Pa/intravenous rhAT. Epithelial and endothelial permeabilities were evaluated with radiolabeled albumin flux across the alveolar barrier (125I- and 131I-labeled albumin). Thrombin-antithrombin (TAT) complexes levels were used as markers of coagulation activation in blood samples and in BAL fluid. Epithelial and endothelial protein permeability were increased in Pa-induced ALI versus control. Intravenous rhAT administration led to further permeability disorders. Administration of rhAT in Pa ALI led to a rise in TAT complexes in ATPNP blood serum and BAL fluids compared with the other groups. In Pa-induced ALI the administration intravenous rhAT leads to major histologic damage, alveolar capillary barrier injury, and permeability increase. Such effects of the inhibition of thrombin activation by rhAT lead to the hypothesis of a probable beneficial role of early coagulation activation in ALI as a factor limiting both the extent of injury and permeability disorders. Our study suggests that inhibition of this initial procoagulative imbalance is potentially dangerous.     

Bile modulates intestinal epithelial barrier function via an extracellular signal related kinase 1/2 dependent mechanism

Objective Obstructive jaundice is frequently complicated by infections and has been associated with increased bacterial translocation and gut mucosal hyperpermeability in animal models. Proper expression of the tight junction (TJ) proteins ZO-1 and occludin is important for normal gut barrier function. We tested whether bile modulates intestinal epithelial ZO-1 and occludin expression.Animals (a) Male C57BL/6 mice; (b) male Sprague-Dawley rats.Interventions (a) Mice were subjected to common bile duct ligation (CBDL) or a sham procedure, and 96 h later all surviving animals were killed for measurement of ileal mucosal permeability to FITC-labeled dextran (everted gut sac technique), bacterial translocation to mesenteric lymph nodes, and ileal epithelial ZO-1 and occludin expression (western blots). (b) Rat IEC-6 enterocytic monolayers were incubated in the presence or absence of graded concentrations of rat bile and/or U0126, an inhibitor of extracellular signal related kinase (ERK) 1/2 activation.Results (a) Compared to sham-treated controls, CBDL significantly increased gut mucosal permeability and bacterial translocation and markedly decreased ileal epithelial expression of ZO-1 and occludin. In a follow-up in vivo experiment, gavaging mice with fresh rat bile twice daily significantly ameliorated the deleterious effects of CBDL on gut barrier function. (b) Addition of 1% (v/v) bile to media enhanced phosphorylation of ERK1/2, increased the expression of ZO-1 and occludin and decreased permeability to FITC-dextran. All of these bile-mediated effects were blocked by 10 µM U0126.Conclusions These data support the view that the presence of bile in the intestinal lumen is essential for normal gut barrier function, possibly because compounds present in bile initiate ERK1/2-dependent signaling that is essential for normal expression of key TJ proteins.This revised version was published online in April 2005 with a corrected section title.Grant support: 5R01 GM 37631-18 from the National Institutes of Health     

人参皂甙Rg1对内毒素性肺损伤血管通透性的影响

目的:探讨人参皂甙Rg1(ginsenosideRg1)对脂多糖(LPS)所致大鼠急性肺损伤(ALI)后肺血管通透性的影响,比较地塞米松(Dex)、人参皂甙对ALI的疗效。方法:将大鼠随机分成对照组、LPS组、Dex+LPS组、Rg1+LPS组,对各组大鼠的肺系数、肺水含量、肺通透指数、肺血管通透性、PO2、PCO2、pH值等指标进行观测,同时将肺组织送病理检查,并进行病理评分。结果:Rg1组的肺系数、肺水含量、肺通透指数、PCO2和病理评分均显著低于LPS组(P<0.01),但高于对照组(P<0.01),其PO2、pH值显著高于LPS组(P<0.01),但低于对照组(P<0.01),Dex+LPS组的肺系数、肺水含量、肺通透指数、PO2、pH值、PCO2和病理评分与Rg1+LPS组相比差异无显著性(P>0.05)。结论:人参皂甙Rg1可降低肺水肿参数,改善肺组织水肿,降低肺血管通透性,作用与Dex类似,其具体作用机制需进一步研究。     

Direct effects of protein S in ameliorating acute lung injury

Summary. Objective: Protein S may exert an anticoagulant activity by enhancing the anticoagulant activity of activated protein C and/or by directly inhibiting the prothrombinase complex. Protein S itself may also directly regulate inflammatory responses and apoptosis. The role of protein S in acute lung injury (ALI) was unknown. This study evaluated the effect of protein S on ALI in the mouse. Methods: Animal ALI was induced in C57/BL6 mice by intratracheal instillation of lipopolysaccharide (LPS). Mice were treated with protein S or saline by intraperitoneal injection 1 h before LPS instillation. Results: Activated protein or protein S alone and combined activated protein C + protein S therapy decreased inflammatory markers and cytokines in mice with acute lung injury. In LPS‐treated mice compared with controls ALI was induced as shown by significantly increased levels of total protein, tumor necrosis factor‐α, interleukin‐6 and monocyte chemoattractant protein‐1 in the bronchoalveolar lavage fluid. Mice with ALI treated with protein S had significantly decreased concentrations of tumor necrosis factor‐α and interleukin‐6 in the lung compared with untreated animals. Thrombin‐antithrombin III, a marker of the activity of the coagulation cascade, was unchanged. Protein S inhibited the expression of cytokines in vitro and increased activation of the Axl tyrosine kinase pathway in A549 epithelial cells. Conclusion: Protein S protects against LPS‐induced ALI, possibly by directly inhibiting the local expression of inflammatory cytokines without affecting coagulation.