Differential local and systemic tumor necrosis factor-alpha responses to a second hit of lipopolysaccharide after hemorrhagic shock

BACKGROUND: The immune response to subsequent stressors after traumatic hemorrhage and resuscitation (HR) may be dependent on timing and counterinflammatory cytokine expression. Our hypothesis was that the timing of the second hit would influence the immune response, and we investigated whether an early second stimulus after HR would result in worse acute lung injury. METHODS: One hour after HR or sham shock (Sham), mice were given intraperitoneal (IP) injections of lipopolysaccharide (LPS) or saline (Sal). Mortality, pulmonary function (PF), bronchoalveolar lavage neutrophil infiltration, and bronchoalveolar lavage (BAL), in addition to serum interleukin (IL)-10, IL-6, and tumor necrosis factor-alpha (TNF-alpha), were assessed. RESULTS: HR blunted serum TNF-alpha expression to LPS (HR+LPS, 424.8 pg/mL; Sham+LPS, 2,248.8 pg/mL; p < 0.05), but primed for increased bronchoalveolar lavage TNF-alpha (HR+LPS, 259.5 pg/mL; Sham+LPS, 23.5 pg/mL; p < 0.05). Elevated serum TNF-alpha corresponded with greater bronchoalveolar lavage neutrophil infiltration (HR+LPS, 0.93%; Sham+LPS, 17.5%; p < 0.05). IL-10 expression was similar in HR and Sham. There were no significant differences in mortality or PF between HR+LPS and Sham+LPS. CONCLUSION: Priming and blunting of the LPS-induced TNF-alpha response occurred concomitantly in two-hit mice, corresponding to an altered pattern of pulmonary inflammation, but no change in PF.     

Nonspecific phosphodiesterase inhibition attenuates liver injury in acute endotoxemia

BACKGROUND: Endotoxemia is accompanied by pro-inflammatory cytokine production, generation of reactive oxygen species, and end-organ injury. Pentoxifylline (PTX), a methylxanthine derivative and phosphodiesterase inhibitor, is known for its anti-inflammatory properties, including down-regulation of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha synthesis. Its effects on liver function and hepatic histology following acute endotoxemia have not been investigated fully. We hypothesized that PTX would preserve liver architecture and function after intravenous lipopolysaccharide (LPS) injection. METHODS: Anesthetized Sprague-Dawley rats received an i.v. bolus injection of LPS (5 mg/kg), LPS + PTX (25 mg/kg), or saline (sham). Plasma concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), TNF-alpha, IL-6, and nitrite were measured at different time points after LPS injection. Liver injury was graded according to a scoring system in a blinded fashion from 0 (normal) to 4 (severe) for hepatocellular necrosis, hemorrhage, and parenchymal and sinusoidal inflammatory infiltrates. Neutrophil infiltration was measured by counting myeloperoxidase (MPO)-positive stained cells. Nuclear factor (NF)-kappaB p-65 was measured by counting positive stained nuclei of hepatocytes and Kupffer cells (KC). Inducible nitric oxide synthase (iNOS) was evaluated by positively stained KC. Data are presented as mean +/- SEM. Analysis of variance with p < 0.05 was considered statistically significant. RESULTS: Animals treated with PTX showed a significant reduction in liver injury score and neutrophil infiltration. Treatment with PTX significantly decreased TNF-alpha, IL-6, and the concentrations of AST and ALT when compared to LPS alone. In addition, a significant decrease in NF-kappaB-positive staining in hepatocytes and KC, as well as in KC iNOS immunostaining was observed in PTX-treated animals compared to the LPS group. CONCLUSIONS: Pentoxifylline downregulates the inflammatory response significantly and decreases liver injury in acute endotoxemia.     

Phosphodiesterase inhibition decreases nuclear factor-kappaB activation and shifts the cytokine response toward anti-inflammatory activity in acute endotoxemia

BACKGROUND: In sepsis, activation of inflammatory cells and excessive production of proinflammatory cytokines leads to tissue injury, multiple organ failure, and death. We postulated that attenuation but not complete abrogation of hyperinflammation is of clinical benefit in sepsis. Because pentoxifylline (PTX) is known to decrease tumor necrosis factor (TNF)-alpha production and to increase anti-inflammatory cytokine synthesis, we tested the hypothesis that PTX treatment would change the pro- and anti-inflammatory balance and decrease mortality in a murine model of acute endotoxemia. In addition, we investigated the effects of PTX on nuclear factor (NK)-kappaB activation using lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (PBMCs) as a model. METHODS: Sprague-Dawley rats were treated with intravenous saline (sham), LPS (lipopolysaccharide, Escherichia coli serotype 0111:B4, 5 mg/kg), and concomitant injection of LPS + PTX (25 mg/kg). Four- and 24-hour plasma TNF-alpha and interleukin (IL)-10 levels, 4-hour white cell count, and 24-hour mortality rates were assessed. The IL-10/TNF-alpha ratio was also calculated. Human PBMCs were stimulated with LPS (10 microg/mL) and exposed to PTX (20 mM) concomitantly or 15 minutes after LPS stimulation. I-kappaB phosphorylation by Western blot and NF-kappaB nuclear translocation by electrophoretic mobility shift assay were assessed. RESULTS: PTX markedly down-regulates TNF-alpha production. IL-10 levels at 4 hours were up-regulated in both LPS and PTX + LPS-treated animals; however, levels were higher in the LPS groups, which paralleled high TNF-alpha levels. In contrast, IL-10 levels at 4 and 24 hours in PTX + LPS-treated animals remained constant, whereas in LPS-treated animals, IL-10 levels at 24 hours were markedly decreased. A shift in the internal milieu balance toward anti-inflammatory activity was confirmed by the calculation of the IL-10/TNF-alpha ratio. These changes were not related to changes in the number of circulating leukocytes. The 24-hour mortality rate was 50% in the LPS group and nil in PTX-treated animals. In LPS-stimulated PBMCs, PTX markedly decreases I-kappaB phosphorylation and NF-kappaB nuclear translocation. CONCLUSION: PTX enhances anti-inflammatory activity and decreases mortality in acute endotoxemia. PTX may be an important adjunct to therapies aiming to modulate the inflammatory response in sepsis.     

Agonist of peroxisome proliferator-activated receptor-gamma, rosiglitazone, reduces renal injury and dysfunction in a murine sepsis model.

BACKGROUND: Agonists of the peroxisome proliferator-activated receptor-gamma may help to regulate inflammation by modulating the production of inflammatory mediators and adhesion molecules. The purpose of this study was to determine the protective effects of rosiglitazone on renal injury in a sepsis model and to explore the mechanism. METHODS: In lipopolysaccharide (LPS)-induced mouse sepsis, we examined the effect of rosiglitazone on LPS-induced overproduction of inflammatory mediators, on the expression of adhesion molecules in renal tubular epithelial cells and on renal function. The mechanism of the protective effect was investigated in vitro using human renal tubular epithelial cells. RESULTS: Rosiglitazone significantly decreased serum tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta levels during sepsis. The levels of blood urea nitrogen and creatinine were significantly lower in mice pre-treated with rosiglitazone than that in LPS-treated mice. Rosiglitazone reduced the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in tubular epithelial cells and interstitium of LPS-treated mice. Pre-treatment with rosiglitazone reduced the infiltration of macrophages/monocytes in renal tissue. In cultured tubular epithelial cells, rosiglitazone significantly decreased the expression of ICAM-1 and VCAM-1 induced by TNF-alpha or IL-1beta, inhibited the degradation of inhibitor kappaBalpha (IkappaBalpha) and blocked the activation of the p65 subunit of nuclear factor (NF)-kappaB. CONCLUSIONS: These results indicate that pre-treatment with rosiglitazone attenuated the production of TNF-alpha and IL-1beta and reduced adhesion molecule expression in renal tubular epithelial cells of LPS-treated mice. Rosiglitazone has an anti-inflammatory effect in renal tubular epithelial cells through the inhibition of NF-kappaB activation.     

In vitro and in vivo effects of salbutamol on neutrophil function in acute lung injury

BACKGROUND: Intravenous salbutamol (albuterol) reduces lung water in patients with the acute respiratory distress syndrome (ARDS). Experimental data show that it also reduces pulmonary neutrophil accumulation or activation and inflammation in ARDS. AIM: To investigate the effects of salbutamol on neutrophil function. METHODS: The in vitro effects of salbutamol on neutrophil function were determined. Blood and bronchoalveolar lavage (BAL) fluid were collected from 35 patients with acute lung injury (ALI)/ARDS, 14 patients at risk from ARDS and 7 ventilated controls at baseline and after 4 days' treatment with placebo or salbutamol (ALI/ARDS group). Alveolar-capillary permeability was measured in vivo by thermodilution (PiCCO). Neutrophil activation, adhesion molecule expression and inflammatory cytokines were measured. RESULTS: In vitro, physiological concentrations of salbutamol had no effect on neutrophil chemotaxis, viability or apoptosis. Patients with ALI/ARDS showed increased neutrophil activation and adhesion molecule expression compared with at risk-patients and ventilated controls. There were associations between alveolar-capillary permeability and BAL myeloperoxidase (r = 0.4, p = 0.038) and BAL interleukin 8 (r = 0.38, p = 0.033). In patients with ALI/ARDS, salbutamol increased numbers of circulating neutrophils but had no effect on alveolar neutrophils. CONCLUSION: At the onset of ALI/ARDS, there is increased neutrophil recruitment and activation. Physiological concentrations of salbutamol did not alter neutrophil chemotaxis, viability or apoptosis in vitro. In vivo, salbutamol increased circulating neutrophils, but had no effect on alveolar neutrophils or on neutrophil activation. These data suggest that the beneficial effects of salbutamol in reducing lung water are unrelated to modulation of neutrophil-dependent inflammatory pathways.     

瑞芬太尼对兔内毒素性急性肺损伤的影响

目的 探讨瑞芬太尼对兔内毒素性急性肺损伤(Au)的影响.方法 健康成年雄性新西兰大白兔30只,体重2.5～3.5 kg,随机分为5组(n=6):对照组(C组)、ALI组、低剂量瑞芬太尼组(LR组)、中剂量瑞芬太尼组(MR组)和高剂量瑞芬太尼组(HR组).C组经30 min静脉输注生理盐水10 ml;ALI组经30 min静脉输注大肠杆菌内毒索(LPS)0.5 mG/kg;LR组、MR组和HR组分别静脉输注瑞芬太尼0.2、0.4和0.8μg·kg~(-1)·min~(-1)至处死,输注15 min时开始给予LPS,方法同ALI组.于LPS输注前即刻(T_0)、输注结束后1、2.5、5.5 h时记录平均动脉血压(MAP)、心率(HR)和气道峰压(P_(peak),测定动脉血氧分压(PaO_2)和血浆细胞间粘附分子1(ICAM-1)浓度,称量肺组织湿重(W)和干重(D),计算W/D比,并在光镜和电镜下观察肺组织病理学结果.结果 与C组比较,ALI组MAP、HR和PaO_2,降低,W/D比、P_(peak)和血浆ICAM-1浓度升高(P<0.05);与ALI组比较,LR组、MR组和HR组MAP、HR 升高,肺组织W/D比降低,P(peak)和血浆ICAM-1浓度降低,PaO_2升高(P<0.05);与LR组比较,MR组和HR组MAP、HR、P(peak)、血浆ICAM-1浓度和肺组织W/D比降低,PaO_2升高(P<0.05);与MR组比较,HR组注肺组织W/D比降低,PaO_2升高(P<0.05).LR组、MR组和HR组肺组织病理学损伤较ALI组减轻.结论 瑞芬太尼可减轻兔内毒素性急性肺损伤,且呈剂量依赖性,其机制可能与抑制ICAM-1的表达有关.     

急性坏死性胰腺炎肺组织炎性介质mRNA表达与肺损伤的关系

目的 探讨急性坏死性胰腺炎(ANP)大鼠肺组织白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)及细胞间黏附分子(ICAM-1)等炎性介质mRNA表达与肺损伤的关系.方法 33只Wistar大鼠随机分为正常对照和胰腺炎不同时间点(1、4、12和24 h)各组,应用3.5%牛磺胆酸钠逆行胰胆管注射制备ANP模型.采用RT-PCR法检测ANP肺组织IL-6、TNF-α及ICAM-1 mRNA表达,同时观察血淀粉酶及脂肪酶、胰腺和肺组织湿/干重比率及病理改变.结果 造模ANP 1 h后肺组织IL-6、TNF-α及ICAM-1 mRNA水平(1.25±0.16、0.33±0.09及082±0.03)较正常对照组(0.07±0.02、0.06±0.02及0.41±0.04)表达增高(P<0.05),并持续升高至12及24 h(分别为1.674±0.14、0.99±0.11、1.17士0.05及1.87±0.05、0.96士0.06、1.11士0.04),同时伴有肺组织病理损害,其严重程度与肺TNF-α及ICAM-1 mRNA表达、肺组织湿/干重比率与TNF-α、IL-6、ICAM-1 mRNA表达的相关系数分别为0.93及0.70(P<0.05).结论 大鼠ANP早期肺组织IL-6、TNF-α及ICAM-1mRNA即过度表达,肺IL-6、TNF-α及ICAM-1mRNA过度表达是ANP肺损害发生的原因之一,肺损伤严重程度与IL-6、TNF-α及ICAM-1mRNA表达的高低有关.     

一氧化碳释放分子对重症急性胰腺炎肺损伤保护作用的实验研究

目的 探讨一氧化碳释放分子(CORM-2)对大鼠重症急性胰腺炎(SAP)肺损伤的保护作用及机制.方法 30只雄性Wistar大鼠随机分为3组(n=10):sham组、SAP组,CORM-2组.以3.5%牛磺胆酸钠逆行注射胰胆管的方法制作SAP模型.CORM-2组于SAP造模0.5 h后经阴茎背动脉注射CORM-2(8 mg/kg).各组均于造模6 h后取材,测定血清肿瘤坏死因子-α(TNF-α)含量;采用RT-PCR法检测肺组织细胞因子诱导的中性粒细胞趋化因子(CINC)及细胞间黏附分子-1(ICAM-1)mRNA的表达;同时检测肺组织髓过氧化物酶(MPO)活性、湿/干重比及对肺脏进行病理学评分.结果 与SAP组相比,CORM-2组血清TNF-α水平、肺组织病理损伤程度、湿/干重比、MPO活性、CINC及ICAM-1 mRNA的表达均显著降低(P＜0.05).结论 应用CORM-2能够降低血清TNF-α水平、下调肺组织CINC及ICAM-1 mRNA的表达,进而有效地抑制肺组织中性粒细胞的大量浸润,从而对SAP肺损伤起到明显的保护作用.     

Role of Kupffer cells in lung injury in rats administered endotoxin 1

The purpose of this study was to investigate the regulation of lung macrophages (Muvarphis) by Kupffer cells (KCs) in lung injury caused by endotoxemia. Phenotypic differences in tissue Muvarphis were also investigated. Muvarphis were isolated from gadolinium chloride (GdCl(3))- or saline-treated rats 2 h after saline or lipopolysaccharide (LPS) administration. Furthermore, rats were given GdCl(3) 24 h prior to LPS administration, and survival rate was assessed for 24 h. Moreover, lung edema was assessed 9 h after LPS injection. Expression of inflammatory mediators was measured in the liver and lung. KCs were divided into three subpopulations based on size and phagocytosis. The expression of TNF-alpha and MIP-2 was greater in the small KCs and lung Muvarphis, while the expression of IL-6, IL-10, and MCP-1 was greater in the large and intermediate KCs. GdCl(3) eliminated ED2-positive large KCs and did not have any effect on the lung Muvarphis. The number of ED1-positive KCs increased significantly in both organs after LPS challenge and was reduced by GdCl(3). The population of ED2-positive KCs did not change following LPS administration. GdCl(3) completely prevented increases in lung microvascular permeability and mortality after LPS infusion. After LPS administration, expression of TNF-alpha and IL-6 increased rapidly and then decreased gradually in both organs. GdCl(3) inhibited these increases in the liver significantly and enhanced the expression of MCP-1 and IL-10 in the lung 9 h after LPS administration. Thus, the heterogeneous response of KCs to endotoxin leads to production of certain cytokines and chemokines that affect lung function.     

Pentoxifylline attenuates stored blood-induced inflammation: A new perspective on an old problem

BACKGROUND: Blood transfusion is a risk factor for many inflammatory processes. Its supernatant fraction has been proven to activate neutrophils. We hypothesized that pentoxifylline (PTX) would attenuate stored blood-induced neutrophil activation and pro-inflammatory mediator production. METHODS: Whole blood was incubated with HBSS, LPS (100 microg/mL), leukoreduced PRBC supernatant + LPS, or supernatant + LPS + PTX (2 mmol/L). TNF-alpha levels were measured by ELISA. MMP-9 was evaluated with zymography. Neutrophil CD66b expression was determined by flow cytometry in blood treated with HBSS, fMLP (1 micromol/L), supernatant + fMLP, or supernatant + fMLP + PTX. RESULTS: TNF-alpha levels were elevated in both the LPS and supernatant + LPS groups (100%; P < 0.01 and 120%; P < 0.01, respectively). PTX administration resulted in a 106% decrease in TNF-alpha (P < 0.0001). MMP-9 levels were increased in all groups. Administration of PTX to the supernatant + LPS group generated a 33% decrease in MMP-9 levels, which was not statistically significant (P < 0.4). Upregulation of CD66b expression was seen in LPS and supernatant + LPS groups. Significant attenuation was seen with PTX (47%; P < 0.01). CONCLUSIONS: PTX downregulates CD66b and TNF-alpha expression in supernatant-induced whole blood. Because blood transfusion can contribute to inflammatory injury, the adjunctive use of PTX may have therapeutic potential.     

Vascular cell adhesion molecule--1 expression is obligatory for endotoxin-induced myocardial neutrophil accumulation and contractile dysfunction

BACKGROUND: Sepsis-induced cardiac dysfunction occurs commonly in critically ill patients and is associated with high mortality rates. Neutrophils play a central role in sepsis-induced lung and liver injury; however, the mechanism of sepsis-induced cardiac dysfunction remains unclear. Vascular cell adhesion molecule-1 (VCAM-1) has been implicated in neutrophil-mediated liver injury during endotoxemia and is also expressed in myocardium. The purposes of this study were to examine the temporal relationship of myocardial VCAM-1 expression with neutrophil accumulation during endotoxemia and to determine whether VCAM-1 mediates neutrophil accumulation and cardiac dysfunction during endotoxemia. METHODS: Mice were subjected to lipopolysaccharide (LPS; 0.5 mg/kg, intraperitoneally). Myocardial VCAM-1 expression and neutrophil accumulation were determined by immunofluorescence staining. Cardiac performance with or without VCAM-1 blocking antibody (5 mg/kg, intravenously) was determined by the Langendorff technique. RESULTS: LPS caused a time-dependent increase in both myocardial VCAM-1 expression and neutrophil accumulation. At 6 hours after LPS, the immunofluorescent intensity for VCAM-1 increased from 2.5 +/- 0.6 x 10(6) in saline solution controls to 19.9 +/- 3.5 x 10(6) (P <.05, analysis of variance), and neutrophil count increased from 2.4 +/- 1.7/mm(2) in saline solution controls to 13.0 +/- 2.5/mm(2) (P <.05). Left ventricular developed pressure was decreased maximally at 6 hours after LPS compared with saline solution controls (29.1 +/- 1.1 mm Hg vs 53.1 +/- 3.9 mm Hg; P <.05). Treatment with VCAM-1 monoclonal antibody abrogated both myocardial neutrophil accumulation and cardiac dysfunction during endotoxemia. CONCLUSIONS: LPS-induced myocardial dysfunction is associated with increased expression of VCAM-1 and with neutrophil accumulation. Blockade of VCAM-1 abrogates myocardial neutrophil accumulation and preserves cardiac function during endotoxemia, which supports a role for VCAM-1 as a therapeutic target for myocardial protection during sepsis.     

内毒素预处理对内毒素血症大鼠肺的作用及机制探讨

目的 观察内毒素预处理对内毒素血症大鼠肺的作用及其机制。方法 将雄性Wistar大鼠84只随机分为7组：生理盐水(NS)组,内毒素脂多糖(LPS)2h、4h、6h组和LPS预处理2h、4h、6h组,每组12只。LPS预处理各组大鼠经腹腔注射LPS0．25mg／kg,24h后再注射LPS0．5mg/kg,NS组和LPS各组在上述时间均给予等容量NS;第2次腹腔注射72h后,LPS各组和LPS预处理各组大鼠经静脉注入(静注)LPS 10mg／kg,NS组注射等量NS。NS组在静注NS后6h,LPS2h、4h、6h组和LPS预处理2h、4h、6h组在静注LPS后2、4、6h时各取6只大鼠取血,行血气分析;取左侧肺组织检测细胞间黏附分子-1(ICAM-1)mRNA及抑制性κB-α(IκB-α)蛋白表达;计数右肺支气管肺泡灌洗液(BALF)中白细胞数,测蛋白含量。上述7组另取6只大鼠,在上述相同时点取全肺,计算肺体指数,测定髓过氧化酶(MPO)。结果 LPS各组大鼠较NS组大鼠肺体指数、BALF中白细胞数和蛋白及肺组织MPO含量均增加,氧分压和HCO3^-下降;而LPS预处理各组大鼠上述各指标变化明显减轻。肺组织ICAM-1 mRNA在LPS2h、4h和6h组表达递增,而在LPS预处理各组表达显著减少;LPS2h组肺组织IκB-α蛋白表达较NS组减少,而LPS预处理2h组较LPS2h组表达增加。结论 内毒素预处理可防止内毒素血症时的肺损伤,可能与内毒素预处理使肺组织IκB-α蛋白生成增加和(或)消耗减少有关。     

急性肺损伤患者血清C5a对肺血管内皮细胞依赖性粘附的影响

目的 探讨急性肺损伤(ALI)早期肺血管内皮细胞损伤的机制及介导血管内皮细胞依赖性粘附的分子基础。方法 夹心酶联免疫吸附(ELISA)法测定和比较正常人及ALI后患者血清中C5a的含量；用流式细胞术(FCM)检测ALI患者血清刺激人肺血管内皮细胞，观测其表面粘附分子：P选择素和细胞间粘附分子(ICAM)—1的表达变化，同时通过检测粘附子血管内皮细胞表面的中性粒细胞(PMN)中髓过氧化物酶(MPO)活性，间接反映血管内皮细胞表面PMN的粘附和聚集。结果 ALI患者血清中C5a含量明显升高，同正常组比较差异有显著性；原代培养的肺血管内皮细胞，受ALI患者血清刺激后，其表面P—选择素的表达迅速增加，20min达到高峰，60min后开始降低，而ICAM—l的表达较慢，3h开始升高，12h达到最高值，24h内无明显下降，仍维持在较高水平；血管内皮细胞表面粘附的PMN中MPO的活性，3h明显升高，12h后达到最高值。结论 ALI患者血清中C5a含量明显升高，促进了PMN在肺微血管内的扣押、聚集进而同血管内皮细胞相粘附；而血管内皮细胞依赖性粘附的增强，主要是源血管内皮细胞上P—选择素和ICAM—l的表达增加，它们在ALI的发生、发展中起到重要作用。     

稳定存活肝移植受者血清细胞因子水平的研究

目的 研究稳定存活的肝移植受者血清细胞因子的表达状况及意义。方法ELISA检测22例原位肝移植患者、13例原发性肝癌患者及12例正常人血清细胞因子的表达情况。流式细胞术分析外周血T细胞表型。结果外周血CD3^ 、CD8^ T细胞百分比以及CD4^ ／CD8^ 比值,各组间比较无统计学差异。肝移植组CD3^ CD25^ T细胞百分比高于正常人组(P=0．022)。血清IL-2、IFN-γ、IL-10、IL-4及INF-α水平,各组间比较差异无显著性。IL-6、ICAM-1和P-seleetin水平肝移植组显著高于正常人组(P值分别为0．048、0．000和0．025)。结论稳定存活的肝移植患者体内效应T细胞仍处于低活化状态,炎症性细胞因子(TNF-α、IL-6)和黏附分子(ICAM-1、P-Seleetin)可能在移植物的慢性损伤过程中发挥了作用。     

Mild hypothermia reduces expression of intercellular adhesion molecule-1 (ICAM-1) and the accumulation of neutrophils after acid-induced lung injury in the rat

BACKGROUND: The pathophysiology of the acute phase of acid-induced lung injury (AILI) has been elucidated. However, once acute respiratory distress syndrome (ARDS) develops, the mortality rate remains high and there is, as yet, no effective therapy. There are reports that application of mild hypothermia is an effective treatment for ARDS. In this study, we hypothesize that mild hypothermia inhibits activation of neutrophils and expression of intercellular adhesion molecule-1 (ICAM-1) in an injured lung. We studied the effects of mild hypothermia on the expression of ICAM-1 and the accumulation of neutrophils after AILI in the rat. METHODS: Male Sprague-Dawley rats were randomly allocated to one of the four groups: control normothermic group, induced mild hypothermia group, acid-instilled normothermic group, and acid-instilled group with mild hypothermia. At 6 h after instillation of acid, lungs were removed to measure neutrophil activity and to detect the expression of ICAM-1 in each group. RESULTS: Oxygenation in acid-instilled rats was significantly impaired as compared to that in non-instilled groups, but induction of mild hypothermia gradually improved oxygenation. Expression of ICAM-1 was enhanced in the acid-instilled normothermic group. By contrast, no overexpression of ICAM-1 and its mRNA was detected in the acid-instilled hypothermic group. In addition, accumulation of neutrophils was markedly inhibited after exposure to mild hypothermia irrespective of the instillation of acid. CONCLUSION: Our data suggest mild hypothermia can inhibit the adhesion, activation, and accumulation of neutrophils during the acute phase of AILI in the rat and may have the potential to reduce ongoing inflammation of ALI or ARDS.     

Role of integrins and intracellular adhesion molecule-1 in lung injury after intestinal ischemia-reperfusion

BACKGROUND: We tested the hypothesis that lung injury after intestinal ischemia-reperfusion (IR) requires the activation of CD11/CD18 glycoprotein complex and its ligand, intracellular adhesion molecule-1 (ICAM-1), on pulmonary endothelial surface. METHODS: Rats were assigned to one of six groups including sham operation, intestinal IR (60/120 min) and IR plus treatment with one of the following monoclonal antibodies against CD11a, CD11b, CD18, and ICAM-1. Pulmonary microvascular permeability, neutrophil accumulation, and expression of adhesion molecules were evaluated. RESULTS: Intestinal IR resulted in lung injury characterized by a marked increase in microvascular permeability, neutrophil accumulation and upregulated expression of leukocyte integrins and ICAM-1. The increase in pulmonary microvascular permability and neutrophil accumulation elicited by intestinal reperfusion was effectively prevented by administration of blocking antibodies against ICAM-1, CD11, and CD18. CONCLUSIONS: These results indicate that adhesion molecules contribute to the lung injury after intestinal IR. Immunoneutralization of certain of these adhesion molecules may prevent intestinal IR-induced lung injury.     

LPS-stimulated PMN activation and proinflammatory mediator synthesis is downregulated by phosphodiesterase inhibition: role of pentoxifylline

BACKGROUND: Excessive production of reactive oxygen species by PMN is associated with tissue damage during inflammation. LPS interacts with the cell surface receptor CD14, which generates transmembrane signals through Toll-like protein 4 leading to mitogen activated protein kinase (MAPK) p38 activation, cytokine synthesis, PMN beta2-integrin expression and oxidative burst. Phosphodiesterase inhibition decreases proinflammatory cytokine production and tissue injury after LPS challenge. Its effects on PMN function after LPS stimulation, however, have not been fully investigated. We hypothesized that LPS-induced TNF-alpha synthesis and subsequent PMN beta2-integrin expression and oxidative burst are downregulated by concomitant treatment with the non-specific phosphodiesterase inhibitor pentoxifylline (PTX). METHODS: Whole blood was incubated with HBSS (control), LPS (100 microg/mL), fMLP (1 micromol/L), LPS+PTX (2 mmol/L) and fMLP+PTX for different time intervals at 37C. Oxidative burst, CD14, and CD-11b expression were measured by flow cytometry. Serum TNF-alpha levels were measured by ELISA. In an attempt to localize the site of action of PTX (proximal or distal to PKC) cell surface receptors were bypassed by PMA stimulation (1 microg/mL) and oxidative burst was measured with and without PTX. RESULTS: Up-regulation of CD14 expression was similar in LPS and LPS+PTX groups. LPS stimulation caused a significant increase in PMN oxidative burst, CD11b expression, and TNF-alpha serum levels. In addition, PMA and fMLP stimulation also caused significant increase in oxidative burst compared with controls. Concomitant addition of PTX to LPS led to a significant decrease in PMN oxidative burst (65%; p < 0.0001), PMN CD11b expression (20%; p = 0.012), and TNF-alpha levels (93%; p < 0.0001). Also, PMA- and fMLP-induced PMN oxidative burst were significantly decreased by PTX [77.5% (p < 0.0001) and 50% (p < 0.01), respectively]. CONCLUSIONS: These results suggest that PTX-inhibition of oxidative burst occurs distal to PKC and may be either due to direct inhibition of NADPH oxidase or inhibition of MAPK phosphorylation, leading to decreased adhesion molecule expression and TNF-alpha synthesis. Its use in clinical scenarios in which PMN are primed may be of clinical relevance.