α2, α2A, α2B/2C-Adrenoceptor subtype antagonists prevent lipopolysaccharide-induced fever response in rabbits

Exogenous pyrogens, e.g., bacterial lipopolysaccharides (LPS), are thought to stimulate macrophages to release endogenous pyrogens, e.g., TNFα, IL-1 β, and IL-6, which act in the hypothalamus to produce fever. We studied the effect of different α₁⁻ and α₂-adrenoceptor subtype antagonists, applied intraperitoneally, on the febrile response induced by LPS in rabbits. Evidence was obtained that prazosin, an α₁⁻ and α_2B/2C-adrenoceptor antagonist; WB-4101, an α₁⁻ and α_2A-adrenoceptor antagonist; CH-38083, a highly selective α₂-adrenoceptor antagonist (α₂: α₁ > 2000); BRL-44408, an α_2A-adrenoceptor antagonist; and ARC-239, an α_2B/2C⁻ and also α₁-adrenoceptor antagonist, blocked the increase of colonic temperature of the rabbit produced by 2 μg/kg LPS administered intravenously without being able in themselves to affect colonic temperature. In addition, prazosin, WB-4101 and CH-38083 antagonized the fall in skin temperature that occurred at the time when the colonic temperature was rising in control animals injected with LPS. All these results suggest that norepinephrine, through stimulation of both α₁⁻andα₂⁻ (α_2A⁻andα_2B/2C⁻) adrenoceptor subtypes, is involved in producing fever in response to bacterial LPS.     

Protein tyrosine kinase inhibitors suppress the production of nitric oxide in mixed glia, microglia-enriched or astrocyte-enriched cultures

Nitric oxide (NO) produced by glial cells has been implicated in the neuropathogenesis of various diseases. However, the signaling transduction pathway(s) for the production of NO in these cells is not well understood. To test whether protein tyrosine kinases (PTKs) are required for signaling events of NO production in glial cells, this study examined the effects of genistein and tyrphostin A25, two potent inhibitors of PTKs, on the production of NO in mouse primary mixed glia, microglia-enriched or astrocyte-enriched cultures exposed to lipopolysaccharide (LPS) or a combination of LPS and interferon-γ (IFNγ). LPS induced a dose-dependent increase in NO production from the mixed glia cultures. The LPS-induced NO production was significantly enhanced by stimulating the cells with IFNγ. Genistein or tyrphostin A25 inhibited the production of NO in both LPS- and IFNγ/LPS-stimulated mixed glia cultures. The production of NO in the stimulated microglia-enriched or astrocyte-enriched cultures was also inhibited by tyrphostin A25. To verify the cellular sources of NO, immunocytochemical staining of inducible NO synthase (iNOS) was followed by staining with the microglia marker Mac-1 or the astrocyte marker glial fibrillary acid protein (GFAP) in microglia-enriched or astrocyte-enriched cultures. The expression of iNOS and the production of NO in microglia-enriched cultures were significantly higher than those in the identically stimulated astrocyte-enriched cultures. These results demonstrate that PTKs are involved in the signaling events of LPS-induced NO production in microglia and astrocytes, and that microglia are more responsive than astrocytes to stimuli which induce NO. These results may provide insights into therapeutic interventions in the pathway for NO production in the brain.     

七拗汤对内毒素诱导加重型哮喘小鼠的作用和机理研究

目的：评价七拗汤对哮喘小鼠气道炎症和高反应性的影响。方法：120只Balb／C小鼠随机分为6组：空白组、模型组、地基米松组、七拗汤高剂量组、七拗汤中剂量组、七拗汤低剂量组。除空白组外,各组小鼠以皮下注射、腹腔注射OVA致敏,雾化吸入OVA激发,内毒素鼻腔滴入诱导。空白组小鼠用PBS进行致敏、激发并在气道内滴入PBS。七拗汤高、中、低剂量组分别予26．8、13．4、6．7g．kg^-1的七拗汤灌胃;地塞米松组予0．0024g．kg。的醋酸地塞米松瘩液,1次／天,连续7天;末次滴鼻激发24h后测定相关指标。结果：模型组中嗜酸性粒细胞和中性细胞数显著上升（P〈O．01）;与模型组相比,地塞米松组嗜酸性粒细胞、中性细胞数量降低（P〈0．05,P〈0．01）。七拗汤高、中、低剂量组嗜酸性粒细胞水平均有下降（P〈O．01）。模型组气道反应性升高,与模型组相比,地塞米松组、七拗汤高、中、低剂量组均有所降低（P〈0．01）。病理显示,模型组小鼠肺组织炎细胞浸润,主要是中性粒细胞和嗜酸性粒细胞,并见气管壁增厚。与模型组相比,地塞米松组病变明显减轻,仅见轻度的支气管周围炎;七拗汤高、中、低剂量组肺泡壁、气道壁病变程度均较模型组减轻,管壁及其周围浸润的炎细胞数量减少,支气管上皮细胞变性不明显,支气管腔内渗出物不同程度地减少。模型组IFN-v和IL-12水平显著降低,IL-4上升（P〈0．05）;与模型组相比,地塞米松组IFN-Y和IL-12水平升高,IL-4降低（P〈0．05）。七拗汤高、中剂量组中IFN-7水平升高,中剂量组中IL-4和IL-12水平与模型组相比具有统计学意义（P〈0．05）;七拗汤低剂量组细胞因子水平改变与模型组相比无意义。结论：七拗汤能够显著抑制卵蛋白致敏激发结合内毒素诱导的加重型哮喘小鼠的气道炎症和气道高反应性,通过调整其细胞因子水平,改善肺组织病理结构等发挥治疗效果。     

Evaluation of serum zonulin level in prediabetic patients

BackgroundThis study aimed to investigate the relationship between lipopolysaccharide (LPS) and zonulin levels and also to show the effect of acute hyperglycemic stress induced by oral glucose tolerance testing (OGTT) on zonulin levels in pre-diabetic patients.MethodsFour groups were constituted according to the criteria of the American Diabetes Association (ADA), based on OGTT results: control group (n:40); prediabetic group (n:56), divided into two subgroups: impaired fasting glucose group (IFG) (n:36), and impaired glucose tolerance (IGT) + IFG group (n:20) and type-2 diabetes mellitus (T2DM) group (n:45).ResultsZonulin and LPS did not significantly differ between the prediabetes and control groups, but were significantly higher in the T2DM group compared to both the prediabetic and the control group (P < 0.001). After OGTT, zonulin and LPS were significantly higher in the prediabetes group compared to the control group (P < 0.01 and P < 0.05, respectively), and significantly lower in the IFG and IFG + IGT groups compared to the T2DM group (P < 0.001, P < 0.001 and P < 0.001, P < 0.001, respectively). A positive correlation was detected between fasting zonulin and 2-hour zonulin (r = 0.727, P < 0.001) and between fasting LPS (r = 0.555, P < 0.001) and 2-hour LPS (r = 0.567, P < 0.001) in the prediabetic group. Increased zonulin and LPS levels and the positive correlation between these levels during the prediabetic period although non significant suggests onset of intestinal permeability.ConclusionsDuring acute hyperglycemia in prediabetic patients, up-regulation of zonulin and LPS may affect intestinal function. The intestines may play a key role in up-regulation of glucose and the pathogenesis of diabetes.     

血必净对严重烧伤患者肠道功能及炎症反应的影响

目的 探讨血必净注射液对严重烧伤患者肠道功能及炎症反应的影响.方法 将同期严重程度相当的32例严重烧伤患者随机(随机数字法)分为血必净治疗组(n=16)和对照组(n=16).对照组按烧伤常规治疗;治疗组在常规治疗基础上给予血必净注射液,每次100 mL,静脉滴注,2次/d,连续使用7 d.检测两组患者治疗前与治疗后3 d和7 d血浆二胺氧化酶(DAO)、内毒素(LPS)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)水平变化.采用SPSS 12.0统计软件进行统计分析.结果 两组烧伤患者治疗后,血浆DAO,LPS,TNF-α及IL-6水平均较治疗前下降(P＜0.05);血必净治疗组在治疗后3 d和7 d,血浆DAO,LPS,TNF-α及IL-6水平明显低于对照组(P＜0.05).结论 血必净注射液可保护烧伤患者肠道功能,减少内毒素人血,对改善严重烧伤患者的炎症反应有积极作用.     

Human colonic myogenic dysfunction induced by mucosal lipopolysaccharide translocation and oxidative stress

Background

Impairment of gastrointestinal motility is frequently observed in patients with severe infection.

Aim

To assess whether exposure of human colonic mucosa to pathogenic lipopolysaccharide affects smooth muscle contractility.

Methods

Human colonic mucosa and submucosa were sealed between two chambers, with the luminal side facing upwards and covered with Krebs solution, with or without lipopolysaccharide from a pathogenic strain of Escherichia coli (O111:B4; 1000 ng/mL), and with the submucosal side facing downwards into Krebs. The solution on the submucosal side was collected following 30-min mucosal exposure to Krebs without (N-undernatant) or with lipopolysaccharide (lipopolysaccharide undernatant). Undernatants were tested for lipopolysaccharide and hydrogen peroxide levels and for their effects on smooth muscle cells in the presence of catalase, indomethacin or MG132.

Results

Smooth muscle cells incubated with N-undernatant had a maximal contraction of 32 ± 5% that was reduced by 62.9 ± 12% when exposed to lipopolysaccharide undernatant. Inhibition of contraction was reversed by catalase, indomethacin and MG132. Lipopolysaccharide levels were higher in the lipopolysaccharide undernatant (2.7 ± 0.7 ng/mL) than in N-undernatant (0.45 ± 0.06 ng/mL) as well as hydrogen peroxide levels (133.75 ± 15.9 vs 82 ± 7.5 nM respectively).

Conclusions

Acute exposure of colonic mucosa to pathogenic lipopolysaccharide impairs muscle cell contractility owing to both lipopolysaccharide mucosal translocation and production of free radicals.     

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。     

Toll-like receptor-mediated tyrosine phosphorylation of paxillin via MyD88-dependent and -independent pathways

Toll-like receptor (TLR)-mediated recognition of pathogens represents one of the most important mechanisms of innate immunity. A proximal signaling event of TLR is the direct binding of an adaptor protein MyD88 to TLR and recruitment of the IL-1R-associated kinase (IRAK). In the present study, we examined the effect of several TLR ligands on protein tyrosine phosphorylation in rat macrophages. Macrophage-activating lipopeptide-2 kDa (MALP2) and lipoarabinomannan were used as activators of TLR2, while lipopolysaccharides (LPS) and lipoteichoic acid were used as TLR4 ligands. All these ligands induced tyrosine phosphorylation of proline-rich tyrosine kinase 2 (Pyk2) and its substrate paxillin, an integrin-associated focal adhesion adaptor protein, in the macrophages. PP2, an inhibitor of Src family tyrosine kinases, prevented the TLR-induced phosphorylation of paxillin and Pyk2 without affecting TLR-induced IRAK activation. MALP2 failed to induce paxillin phosphorylation in the macrophages from MyD88-knockout mice. In contrast, the effect of LPS weakened, but was still observed even in the MyD88-deficient cells. Thus, TLR regulate the function of paxillin in an Src family-dependent mechanism through both MyD88-dependent and MyD88-independent pathways.     

The molecular mechanism of species-specific recognition of lipopolysaccharides by the MD-2/TLR4 receptor complex

Lipid A, a component of bacterial lipopolysaccharide, is a conserved microbe-associated molecular pattern that activates the MD-2/TLR4 receptor complex. Nevertheless, bacteria produce lipid A molecules of considerable structural diversity. The human MD-2/TLR4 receptor most efficiently recognizes hexaacylated bisphosphorylated lipid A produced by enterobacteria, but in some animal species the immune response can be elicited also by alternative lipid A varieties, such as tetraacylated lipid IVa or pentaacylated lipid A of Rhodobacter spheroides. Several crystal structures revealed that hexaacylated lipid A and tetraacylated lipid IVa activate the murine MD-2/TLR4 in a similar manner, but failed to explain the antagonistic vs. agonistic activity of lipid IVa in the human vs. equine receptor, respectively. Targeted mutagenesis studies of the receptor complex revealed intricate combination of electrostatic and hydrophobic interactions primarily within the MD-2 co-receptor, but with a contribution of TLR4 as well, that contribute to species-specific recognition of lipid A. We will review current knowledge regarding lipid A diversity and species-specific activation of the MD-2/TLR4 receptor complex in different species (e.g. human, mouse or equine) by lipid A varieties.     

羟基积雪草苷与积雪草苷对LPS诱导大鼠发热模型的影响

目的观察积雪草苷和羟基积雪草苷的解热作用,并比较两者在解热作用上的差异。方法将80只SD大鼠随机分为空白组、模型组(LPS 100μg/kg)、溶酶对照组(羧甲基纤维素钠)、积雪草苷5,15,45 mg/kg、羟基积雪草苷10,20,40mg/kg、对乙酰氨基酚50 mg/kg组。腹腔注射LPS(100μg/kg)建立SD大鼠发热模型,绘制各组平均体温变化曲线,比较测量体温与基础体温差值ΔT。结果羟基积雪草苷(10,20,40 mg/kg)与积雪草苷(5,15,45 mg/kg)对LPS诱导的SD大鼠发热模型体温有显著的降温作用(P<0.05)。结论羟基积雪草苷和积雪草苷对LPS诱导的SD大鼠发热模型的体温均有降温作用,积雪草苷在某些时间点(如LPS注射5 h后)降温效应优于羟基积雪草苷。