Inhibition of nitric oxide synthase delays the development of tolerance to LPS in rats

The role of nitric oxide (NO) was investigated in endotoxin (lipopolysaccharide, LPS) tolerance in freely moving biotelemetered rats. We monitored changes in febrile response and feeding behavior (food intake, water intake) during the development of tolerance to repeated intraperitoneal injections of LPS (50 microg/kg) along with injections of N(omega)-nitro-L-arginine methyl ester (L-NAME; 50 mg/kg), an inhibitor of NO synthase. Rats were treated with LPS and L-NAME for three consecutive days. On the fourth day, all rats were injected with LPS alone. Control rats were injected with saline along with saline or with L-NAME for four consecutive days. Rats repeatedly injected with LPS became tolerant to pyrogenic and hypophagic/cachexic effects of LPS as early as on the second day of experiment. The treatment with L-NAME prevented the attenuation of febrile response following the second LPS injection. Moreover, the depressive effects of LPS on body weight as well as on water and food intake were prolonged in rats treated with a combination of L-NAME and LPS. Injection of LPS caused a 3.5-fold increase in plasma nitrite within 3 h and nitrite levels remained significantly elevated 6 and 24 h after LPS. Rats injected secondly with LPS did have still 2.5- to 3-fold increase in plasma nitrite levels 3 and 6 h, but not 24 h, after injection. Third injection of LPS did not elevate nitrite level in plasma. Taken together, presented data provide clear evidence that NO formation is involved in mechanisms responsible for development of early-stage tolerance to endotoxin.     

Superantigen and endotoxin synergize in the induction of lethal shock

Endotoxin (lipopolysaccharide; LPS) and superantigens (exotoxins) have been identified as potent inducers of lethal shock. While endotoxin primarily interacts with CD 14 receptors on macrophages, superantigens like the staphylococcal enterotoxin B (SEB) preferentially activate T cells. Both cell types are triggered to release pro-inflammatory cytokines that in turn induce lethal shock. We analyzed whether endotoxin and superantigen interact during the induction phase of lethal shock. We report that LPS and SEB operate synergistically. Lethal doses of both inducers were reduced 100-fold when given in combination. The induced serum levels of tumor necrosis factor, interleukin-6, and interferon-γ (IFN-γ) were elevated and remained high for a prolonged period. Moreover, synergistic action of LPS and SEB induced lethal toxic shock even without presensitization of mice with D -galactosamine (D -GalN). Opposed to D -GalN-pretreated mice, mice injected with LPS and SEB showed less liver damage, but rather apoptosis of epithelial cells in the bowel. Cyclosporin A and treatment with anti-IFN-γ monoclonal antibody blocked the synergistic action of LPS and SEB, indicating that T cell-derived IFN-γ is the mediator of the observed synergism. Concomitant injection of LPS and SEB had no influence on SEB-induced T cell deletion and anergy induction. Since Gram-positive and Gram-negative bacteria can be recovered from septic blood samples, the synergistic action of endotoxin and superantigens might be relevant during lethal septicemia.     

大鼠肝缺血再灌注损伤对心脏能量代谢和结构的影响及其机制

目的：探讨肝缺血再灌注损伤对心脏能量代谢和结构的影响及其可能的发生机制。方法：健康雄性Wistar大鼠48只，随机分为对照组、缺血30 min组（I组）及缺血30 min再灌注即刻组、2 h组、4 h组和6 h组（I/R组、I/R 2 h组、I/R 4 h组和I/R 6 h组），每组8只。用偶氮显色法测定血清中的内毒素，用放射免疫法测定心肌组织胰岛素和胰岛素抗体，取心肌制备组织匀浆测丙二醛（MDA）、髓过氧化物酶（MPO），乳酸含量。 结果：在肝缺血再灌注损伤过程中，内毒素在I组和I/R组达到高峰，随着再灌注时间的延长逐渐下降，但仍高于对照组（P<0.05）。I组及I/R各组MDA的含量明显高于对照组，在I/R 2 h组、I/R 4 h组、I/R 6 h组差别更为明显（P＜0.05）；再灌注各组MPO活性明显高于对照组、I组（P＜0.05）；随着再灌注时间的延长，心肌组织中乳酸含量明显增加（P＜0.05），但在I/R 6 h组呈下降趋势（P＜0.05）；胰岛素的含量在I/R 4 h组和I/R 6 h组明显下降（P＜0.05）；而胰岛素抗体在各组间无显著差异（P＞0.05）。结论：肝缺血再灌注损伤过程中，肠源性内毒素吸收入血及肝脏解毒功能的降低所致的内毒素血症可能是引起心脏能量代谢和结构改变的始动环节。     

Crosstalk between inflammation and thrombosis

Inflammation shifts the hemostatic mechanisms in favor of thrombosis. Multiple mechanisms are at play including up regulation of tissue factor leading to the initiation of clotting, amplification of the clotting process by augmenting exposure of cellular coagulant phospholipids, inhibition of fibrinolysis by elevating plasminogen activator inhibitor 1 (PAI-1) and decreases in natural anticoagulant pathways, particularly targeted toward down regulation of the protein C anticoagulant pathway through multiple mechanisms. The decreased function of the natural anticoagulant pathways may be particularly problematic because these appear to play a role in dampening inflammatory responses. The protein C anticoagulant pathway provides a useful model for the impact of inflammation on coagulation. This pathway plays a major role in preventing microvascular thrombosis. The pathway is initiated when thrombin binds to thrombomodulin (TM) on the surface of the endothelium. An endothelial cell protein C receptor (EPCR) augments protein C activation by the thrombin–TM complex more than 10-fold in vivo. EPCR is shed from the endothelium by inflammatory mediators and thrombin. EPCR binds to activated neutrophils in a process that involves proteinase 3 and Mac-1 and appears to inhibit leukocyte extravisation. EPCR can undergo translocation from the plasma membrane to the nucleus where it redirects gene expression. During translocation it can carry activated protein C (APC) to the nucleus, possibly accounting for the ability of APC to modulate inflammatory mediator responses in the endothelium. TNF and other inflammatory mediators can down-regulate EPCR and TM and IL-6 can depress levels of protein S in experimental animals. Inhibition of protein C pathway function increases cytokine elaboration, endothelial cell injury and leukocyte extravisation in response to endotoxin, processes that are decreased by infusion of APC. In vitro, APC inhibits TNF elaboration from monocytes and to block leukocyte adhesion to selectins. Since thrombin can elicit many inflammatory responses in microvascular endothelium, loss of control of microvascular thrombin generation due to impaired protein C pathway function probably contributes to microvascular dysfunction in sepsis.     

脂多糖诱导的小鼠腹腔巨噬细胞基因表达谱分析

目的　利用基因芯片技术分析脂多糖 (LPS)活化的小鼠腹腔巨噬细胞基因表达谱 ,以更全面地了解LPS诱导的巨噬细胞反应。方法　以未刺激的和用 1mg/LLPS刺激的小鼠腹腔巨噬细胞制备3 3 P标记的cDNA探针 ,分别与含有 1176个已知基因的小鼠cDNA芯片杂交。结果　活化组和未刺激组间的 2倍差异表达基因为 118个 ,3倍差异表达基因为 6 9个 ,其中 4 4个上调 ,2 5个下调。转录因子、细胞内信号调节蛋白、炎症细胞因子和细胞凋亡相关基因的转录发生明显的调节变化。结论提供了LPS活化的巨噬细胞综合基因表达信息 ,并筛选出一些新的可能与LPS活化相关的基因。     

Airborne endotoxin associated with particles of different sizes and affected by water content in handled straw

High exposures to endotoxin are observed in environments where organic materials are handled and lower exposures are found in e.g. indoor air. Inhaled endotoxin contributes significantly to the induction of airway inflammation and dysfunction. The size of an inhaled particle influences the deposition in the airways and the following health symptoms. The objective is to characterise the distribution of endotoxin on airborne particles of different sizes in straw storage halls with high exposure and in other environments with lower exposure levels to endotoxin. Furthermore we have studied the influence of water content of handled straw on the size distribution of endotoxin containing particles. Total, inhalable, thoracic and respirable endotoxin and particles have each been quantified in aerosols from boiler rooms and straw storage halls at 24 power plants, including 21 biofuel plants. Inhalable, thoracic and respirable endotoxin have been quantified in aerosols from offices and outdoor air. The endotoxin concentration was higher in airborne thoracic dust than in airborne ‘total dust’. The median respirable fraction in the straw storage halls, boiler rooms at biofuel plants, boiler rooms at conventional plants, offices and outdoors was respectively 42%, 9%, 19%, 24% and 34%. Thoracic endotoxin per number of thoracic particles was higher than respirable endotoxin per number of respirable particles at the biofuel plants. In straw storage halls the fraction of endotoxin of respirable size was highest on the days with lowest water content in the received straw. Furthermore the exposures to all endotoxin fractions were highest on days with the lowest water content in the received straw. In conclusion the highest exposures and concentrations of endotoxin occur or tend to occur from thoracic dust. A high variation in endotoxin concentrations and in fractions of respirable or thoracic size is found in the different working areas. This is important in the risk assessment and makes attempts to influence the endotoxin exposure a possibility. Water content in straw affected the concentration, exposure level and size distribution of airborne endotoxin.     

The role of Kupffer cells in hepatic diseases

Kupffer cells (KCs) constitute 80–90% of the tissue macrophages present in the body. Essential to innate and adaptive immunity, KCs are responsible for the swift containment and clearance of exogenous particulates and immunoreactive materials which are perceived as foreign and harmful to the body. Similar to other macrophages, KCs also sense endogenous molecular signals that may result from perturbed homeostasis of the host. KCs have been implicated in host defense and the pathogenesis of various hepatic diseases, including endotoxin tolerance, liver transplantation, nonalcoholic fatty liver disease, and alcoholic liver disease. In this review, we summarized some novel findings associated with the role of KCs in hepatic diseases, such as the origin and mechanisms KCs polarization, molecular basis for caspase-1 activation called “non-canonical inflammasome pathway” involving the cleavage of Gsdmd by caspase-11, the important role of microRNA in liver transplantation, and so on. A better understanding of KCs biological characteristics and immunologic function in liver homeostasis and pathology may pave the way to investigate new diagnostic and therapeutic approaches for hepatic diseases.     

A new approach using tissue alkaline phosphatase histochemistry to identify Crohn's disease

In the present study, we investigate intestinal alkaline phosphatase activity in mucosal biopsies in patients with inflammatory bowel disease. Crohn's disease influences the alkaline phosphatase activity in the intestine, increasing its activity. We present a histochemistry-based method for alkaline phosphatase that is useful for the identification of Crohn's disease and the differentiation of ulcerative colitis.     

肾上腺素对内毒素致大鼠炎症性肝损害的保护作用

目的 探讨肾上腺素（Epi）对内毒素（脂多糖，LPS）致大鼠炎症性肝损害的保护作用及其作用机制。方法 50只SD大鼠随机分为5组（每组各10只）：对照组：静脉滴注生理盐水2．4mL·kg^-1·h^-1；LPS组：静脉注射LPS6mg·kg^-1后，静脉滴注生理盐水2．4mL·kg^-1·h^-1；低、中和高剂量Epi组：静脉注射LPS6mg·kg^-1后，分别静脉滴注Epi0．12、0．3和0．6μg·kg^-1·min^-1。在LPS注射前、注射后2和6h3个时点取血，检测血清ALT、AST、TNF-α、IL-1β和IL-10水平，并在6h时点观察肝脏的组织病理学改变。结果 LPS组注射LPS后2、6h血清AST和ALT水平较对照组显著升高。同时血清TNF-α、IL-1β和IL-10水平亦较对照组显著升高（P〈0．05）。病理检查结果示：LPS组肝窦扩张、充血，局灶性肝细胞坏死。高剂量Epi可显著降低血清AST和ALT水平，减轻肝脏病理损伤，并显著可降低TNF-α水平和升高IL-10水平（1）8LPS组，P均〈0．05），但对IL-1β水平无影响。中、低剂量Epi对LPS致炎症性肝损害无明显保护作用。结论 Epi可通过抗炎作用减轻LPS诱导的炎症性肝损害。     

Thymulin,A Thymic Peptide,Prevents the Overproduction of Pro-Inflammatory Cytokines and Heat Shock Protein Hsp70 in Inflammation-Bearing Mice

The effects of synthetic analogue of peptide hormone thymulin, which is normally produced by thymic epithelial cells, on immune cells activity and blood cytokine profile had been studied in male NMRI mice with acute inflammation induced by injection of lipopolysaccharide from gram-negative bacteria (LPS, 250 μg/100 g of body weight). Inflammation induced by LPS resulted in accumulation of several plasma pro-inflammatory cytokines, IL-1β, IL-2, IL-6, TNF-α, interferon-γ, and also IL-10, anti-inflammatory cytokine. Thymulin previously injected in dose of 15 μg/100 g body weight, prevented the accumulation of proinflammatory cytokines in plasma. Thymulin also prevented LPS-induced up-regulation of production of several cytokines by spleen lymphocytes and peritoneal macrophages. Added in vitro, thymulin decreased the peak of TNF-α production in macrophages cultivated with LPS. In addition, thymulin lowered the peak of Hsp70 production induced by LPS treatment. The results indicate that thymulin having significant anti-inflammatory effect may be promising in clinical application.