IL-33及其受体ST2的研究进展

IL-33是的IL-1家族的新成员,通过受体ST2活化Th2辅助性T细胞。近来在自身免疫性疾病、变态反应性疾病和心脏疾病的研究表明IL-33是炎症性因子。本文总结了IL-33和其受体ST2信号通路的研究进展。     

Inhibiting PTEN Protects Hippocampal Neurons against Stretch Injury by Decreasing Membrane Translocation of AMPA Receptor GluR2 Subunit

The AMPA type of glutamate receptors (AMPARs)-mediated excitotoxicity is involved in the secondary neuronal death following traumatic brain injury (TBI). But the underlying cellular and molecular mechanisms remain unclear. In this study, the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in GluR2-lacking AMPARs mediated neuronal death was investigated through an in vitro stretch injury model of neurons. It was indicated that both the mRNA and protein levels of PTEN were increased in cultured hippocampal neurons after stretch injury, which was associated with the decreasing expression of GluR2 subunits on the surface of neuronal membrane. Inhibition of PTEN activity by its inhibitor can promote the survival of neurons through preventing reduction of GluR2 on membrane. Moreover, the effect of inhibiting GluR2-lacking AMPARs was similar to PTEN suppression-mediated neuroprotective effect in stretch injury-induced neuronal death. Further evidence identified that the total GluR2 protein of neurons was not changed in all groups. So inhibition of PTEN or blockage of GluR2-lacking AMPARs may attenuate the death of hippocampal neurons post injury through decreasing the translocation of GluR2 subunit on the membrane effectively.     

Pseudomonas aeruginosa Induced Lung Injury Model

In order to study human acute lung injury and pneumonia, it is important to develop animal models to mimic various pathological features of this disease. Here we have developed a mouse lung injury model by intra-tracheal injection of bacteria Pseudomonas aeruginosa (P. aeruginosa or PA). Using this model, we were able to show lung inflammation at the early phase of injury. In addition, alveolar epithelial barrier leakiness was observed by analyzing bronchoalveolar lavage (BAL); and alveolar cell death was observed by Tunel assay using tissue prepared from injured lungs. At a later phase following injury, we observed cell proliferation required for the repair process. The injury was resolved 7 days from the initiation of P. aeruginosa injection. This model mimics the sequential course of lung inflammation, injury and repair during pneumonia. This clinically relevant animal model is suitable for studying pathology, mechanism of repair, following acute lung injury, and also can be used to test potential therapeutic agents for this disease.     

NDRG2在大鼠肺缺血再灌注损伤中的表达

目的:通过建立大鼠肺缺血再灌注损伤(Lung ischemia-reperfusion injury,LIRI)模型,观察肺缺血再灌注损伤后,肺组织中N-myc下游调节基因2(N-myc downstream regulated gene,NDRG2)表达水平的变化.方法:将70只健康成年雄性SD大鼠随机分成对照组(C)、缺血组(I)、缺血再灌注组(I/R)(后两组各含3个亚组),每组10只.麻醉固定大鼠,颈部切口行气管插管.右侧开胸,肺缺血组依次分别选择游离夹闭右肺门(即右主支气管,右肺动、静脉)缺血30 min、60 min、120 min后,麻醉处死大鼠获取肺组织.肺缺血再灌注组同样选择游离夹闭右肺门,于夹闭右肺门60 min后松开,分别取再灌注30 min、60 min、120m in后麻醉处死大鼠获取肺组织样本.采用免疫组化对肺组织NDRG2进行蛋白定位检测、RT-PCR对肺组织NDRG2 mRNA含量进行检测、Western-blot对肺组织NDRG2蛋白含量进行检测.结果:肺缺血组与对照组比较,肺组织NDRG2的表达无明显变化(P＞0.05);肺缺血再灌注组与对照组比较,NDRG2蛋白含量和mRNA表达量逐渐下降,在60 min时达最低,之后又有所回升,但仍低于对照组(P＜0.05).结论:肺缺血再灌注损伤可下调肺组织中NDR G2的表达含量,NDRG2可能是肺缺血再灌注损伤的靶向调控位点.     

NMDA Receptor Antagonist Attenuates Bleomycin-Induced Acute Lung Injury

Background

Glutamate is a major neurotransmitter in the central nervous system (CNS). Large amount of glutamate can overstimulate N-methyl-D-aspartate receptor (NMDAR), causing neuronal injury and death. Recently, NMDAR has been reported to be found in the lungs. The aim of this study is to examine the effects of memantine, a NMDAR channel blocker, on bleomycin-induced lung injury mice.

Methods

C57BL/6 mice were intratracheally injected with bleomycin (BLM) to induce lung injury. Mice were randomized to receive saline, memantine (Me), BLM, BLM plus Me. Lungs and BALF were harvested on day 3 or 7 for further evaluation.

Results

BLM caused leukocyte infiltration, pulmonary edema and increase in cytokines, and imposed significant oxidative stress (MDA as a marker) in lungs. Memantine significantly mitigated the oxidative stress, lung inflammatory response and acute lung injury caused by BLM. Moreover, activation of NMDAR enhances CD11b expression on neutrophils.

Conclusions

Memantine mitigates oxidative stress, lung inflammatory response and acute lung injury in BLM challenged mice.     

脑缺血大鼠肺组织NGF/TrkA表达变化及其意义

目的:探讨大鼠脑缺血后肺组织神经生长因子(nerve growth factor,NGF)/酪氨酸蛋白激酶A(tropomyosin-related kinase A,TrkA)表达的变化。方法:成年雄性大鼠随机分为假手术组和脑缺血后6 h、24 h及48 h组,每组8只。建立大脑中动脉永久性局灶性缺血模型,术后于各时间点麻醉处死大鼠后,测定肺组织湿重/干重(W/D),光镜下观察HE染色肺组织病理学改变;Western blot法检测肺组织NGF、TrkA蛋白表达。结果:与假手术组相比,脑缺血后6 h肺组织W/D有增加,差异无统计学意义(P>0.05),而脑缺血后24 h及48 h肺组织W/D均有显著增高(P<0.05),其中以24 h组最明显(P<0.01);脑缺血后6 h肺组织出现轻度充血、水肿及炎性改变,24 h及48 h组肺泡结构破坏明显。病理学评分结果显示,脑缺血后24 h及48 h组大鼠肺组织病理评分较假手术组显著升高(P<0.05);Western blot法显示,脑缺血6 h肺组织中NGF表达增加(P<0.05),48 h时表达有下降趋势,但仍高于假手术组(P<0.05)。而肺组织中TrkA表达在脑缺血6h有下降(P>0.05),24 h下降明显(P<0.05),48 h时TrkA蛋白表达虽有上升,仍显著低于假手术组(P<0.05)。结论:大鼠肺组织NGF/TrkA的动态变化可能参与了脑缺血后肺损伤的病理生理过程。     

Toc Receptor Dimerization Participates in the Initiation of Membrane Translocation during Protein Import into Chloroplasts

The post-translational import of nucleus-encoded preproteins into chloroplasts occurs through multimeric translocons in the outer (Toc) and inner (Tic) membranes. The high fidelity of the protein import process is maintained by specific recognition of the transit peptide of preproteins by the coordinate activities of two homologous GTPase Toc receptors, Toc34 and Toc159. Structural and biochemical studies suggest that dimerization of the Toc receptors functions as a component of the mechanism to control access of preproteins to the membrane translocation channel of the translocon. We show that specific mutations that disrupted receptor dimerization in vitro reduced the rate of protein import in transgenic Arabidopsis compared with the wild type receptor. The mutations did not affect the GTPase activities of the receptors. Interestingly, these mutations did not decrease the initial preprotein binding at the receptors, but they reduced the efficiency of the transition from preprotein binding to membrane translocation. These data indicate that dimerization of receptors has a direct role in protein import and support a hypothesis in which receptor-receptor interactions participate in the initiation of membrane translocation of chloroplast preproteins as part of the molecular mechanism of GTP-regulated protein import.     

小剂量脂多糖气管内滴注制备急性肺损伤动物模型的探究

目的急性肺损伤/急性呼吸窘迫综合征(Acute lung injury/Acute respiratory distress syndrome,ALI/ARDS)发病率与死亡率均较高,发病机制迄今尚不完全清楚,也无特效的治疗方法。本实验成功地建立一种轻型ALI动物模型,为研究该病的早期发病机制及治疗提供重要的观察手段。方法给予45只SD大鼠气管内灌注内毒素0.5 mL/kg(LPS 200μg/mL),观察4、12、24及48 h光镜和电镜下的病理改变;观察支气管肺泡灌洗液(BALF)中细胞分数、白蛋白等。结果在观察时间内实验动物均存活。LPS给予后实验组病理检查发现①肺间质水肿;②肺泡腔内多形核中性粒细胞(PMN)浸润和红细胞渗出;③肺泡Ⅰ型和Ⅱ型肺泡上皮细胞破坏。以LPS给予后4~12 h为最严重。BALF中PMN及白蛋白明显增加。结论气管内灌注内毒素0.5 mL/kg(LPS200μg/mL)成功地建立急性肺损伤动物模型。     

脑死亡诱发肺损伤机制及治疗进展

肺移植是终末期肺疾病的最终治疗方案.供体短缺是肺移植所面临的主要问题.目前,脑死亡供体是肺移植供体的重要来源.然而,脑死亡过程会诱发急性肺损伤并且加重肺缺血再灌注损伤.脑死亡肺损伤机制主要包括三个方面:血流动力学的剧烈改变、全身炎症改变、神经内分泌的改变.其肺损伤表现于肺间质水肿、血浆外漏和肺泡出血,造成肺水肿等.深入探索脑死亡肺损伤的机制,将对治疗及实施肺保护提供有力的依据.     

Cholesterol Translocation in a Phospholipid Membrane

Cholesterol (CHOL) molecules play a key role in modulating the rigidity of cell membranes and controlling intracellular transport and signal transduction. Using an all-atom molecular dynamics approach, we study the process of CHOL interleaflet transport (flip-flop) in a dipalmitoylphosphatidycholine (DPPC)-CHOL bilayer over a time period of 15 μs. We investigate the effect of the flip-flop process on mechanical stress across the bilayer and the role of CHOL in inducing molecular order in bilayer leaflets. The simulations are carried out at physiologically relevant CHOL concentration (30%), temperature (323 K), and pressure (1 bar). CHOL flip-flop events are observed with a rate constant of 3 × 10⁴ s⁻¹. Once a flip-flop event is triggered, a CHOL molecule takes an average of 73 nanoseconds to migrate from one bilayer leaflet to the other.     

百草枯致急性肺损伤大鼠模型的建立

目的建立一种百草枯诱导的急性肺损伤（ALI）大鼠模型。方法将20只SD大鼠随机分为正常对照组10只、实验组10只。实验组一次性口服灌胃百草枯（PQ）80mg／kg,于给药后1天处死大鼠,观察光镜下肺组织病理改变、肺动脉血氧分压（PaO2）、支气管肺泡灌洗液（BALF）蛋白含量等。结果给予百草枯1天后肺形态学出现显著异常,PaO2及BALF蛋白含量出现显著改变。结论一次性灌胃百草枯80mg／kg成功建立急性肺损伤动物模型。     

Baicalein Reduces Airway Injury in Allergen and IL-13 Induced Airway Inflammation

Background

Baicalein, a bioflavone present in the dry roots of Scutellaria baicalensis Georgi, is known to reduce eotaxin production in human fibroblasts. However, there are no reports of its anti-asthma activity or its effect on airway injury.

Methodology/Principal Findings

In a standard experimental asthma model, male Balb/c mice that were sensitized with ovalbumin (OVA), treated with baicalein (10 mg/kg, ip) or a vehicle control, either during (preventive use) or after OVA challenge (therapeutic use). In an alternate model, baicalein was administered to male Balb/c mice which were given either IL-4 or IL-13 intranasally. Features of asthma were determined by estimating airway hyperresponsiveness (AHR), histopathological changes and biochemical assays of key inflammatory molecules. Airway injury was determined with apoptotic assays, transmission electron microscopy and assessing key mitochondrial functions. Baicalein treatment reduced AHR and inflammation in both experimental models. TGF-β₁, sub-epithelial fibrosis and goblet cell metaplasia, were also reduced. Furthermore, baicalein treatment significantly reduced 12/15-LOX activity, features of mitochondrial dysfunctions, and apoptosis of bronchial epithelia.

Conclusion/Significance

Our findings demonstrate that baicalein can attenuate important features of asthma, possibly through the reduction of airway injury and restoration of mitochondrial function.     

Vesnarinone Represses the Fibrotic Changes in Murine Lung Injury Induced by Bleomycin

We investigated the potential usefulness of vesnarinone, a novel cytokine inhibitor, for the treatment of lung fibrosis using a murine model of bleomycin (BLM)-induced pulmonary fibrosis. Mice were fed a control diet (n=42), or a diet containing low (n=42) or high (n=42) dose of vesnarinone. Dietary intake of vesnarinone minimized the BLM toxicity as reflected by significant decreases in numbers of inflammatory cells, KC, and soluble TNF receptors in the bronchoalveolar lavage fluid. A quantitative evaluation of histology demonstrated significantly mild lung parenchymal lesions in BLM-treated mice fed with diet containing high dose of vesnarinone than in the control diet group. Consistent with the histopathology, hydroxyproline levels in lung tissue from BLM-treated mice fed with diet containing vesnarinone were significantly lower than that from mice fed with control diet. We concluded that vesnarinone inhibits BLM-induced pulmonary fibrosis, at least in part, by the inhibition of acute lung injuries in the early phase.     

A complicated liaison: IL-33 and IL-33R in arthritis pathogenesis

Interruption of cytokine signaling, by targeting either the cytokine itself or its cellular receptor, is a mainstay in the therapy for patients with rheumatic diseases. Interleukin (IL)-33, a member of the IL-1 cytokine family, has emerged as an important mediator of inflammatory responses. In a side-by-side examination of IL-33-deficient and IL-33 receptor (IL-33R)-deficient mice in the K/BxN serum transfer model, arthritis was ameliorated in the IL-33R knockout (KO) mice but not in the IL-33 KO mice. These findings complement previous knowledge on IL-33R signaling, demonstrating that the IL-33R cross-activates other signaling pathways in addition to IL-33-mediated signals. The results reported by Martin and colleagues in a previous issue of Arthritis Research & Therapy underline the clinical relevance of IL-33R cross-signaling and further illustrate that targeting a cytokine receptor (IL-33R) can have completely different clinical outcomes than targeting the respective cytokine.     

IL-33-Dependent Endothelial Activation Contributes to Apoptosis and Renal Injury in Orientia tsutsugamushi-Infected Mice

Endothelial cells (EC) are the main target for Orientia tsutsugamushi infection and EC dysfunction is a hallmark of severe scrub typhus in patients. However, the molecular basis of EC dysfunction and its impact on infection outcome are poorly understood. We found that C57BL/6 mice that received a lethal dose of O. tsutsugamushi Karp strain had a significant increase in the expression of IL-33 and its receptor ST2L in the kidneys and liver, but a rapid reduction of IL-33 in the lungs. We also found exacerbated EC stress and activation in the kidneys of infected mice, as evidenced by elevated angiopoietin (Ang) 2/Ang1 ratio, increased endothelin 1 (ET-1) and endothelial nitric oxide synthase (eNOS) expression. Such responses were significantly attenuated in the IL-33^-/- mice. Importantly, IL-33^-/- mice also had markedly attenuated disease due to reduced EC stress and cellular apoptosis. To confirm the biological role of IL-33, we challenged wild-type (WT) mice with a sub-lethal dose of O. tsutsugamushi and gave mice recombinant IL-33 (rIL-33) every 2 days for 10 days. Exogenous IL-33 significantly increased disease severity and lethality, which correlated with increased EC stress and activation, increased CXCL1 and CXCL2 chemokines, but decreased anti-apoptotic gene BCL-2 in the kidneys. To further examine the role of EC stress, we infected human umbilical vein endothelial cells (HUVEC) in vitro. We found an infection dose-dependent increase in the expression of IL-33, ST2L soluble ST2 (sST2), and the Ang2/Ang1 ratio at 24 and 48 hours post-infection. This study indicates a pathogenic role of alarmin IL-33 in a murine model of scrub typhus and highlights infection-triggered EC damage and IL-33-mediated pathological changes during the course of Orientia infection.     

Estrogen Receptor Hormone Agonists Limit Trauma Hemorrhage Shock-Induced Gut and Lung Injury in Rats

Background

Acute lung injury (ALI) and the development of the multiple organ dysfunction syndrome (MODS) is a major cause of death in trauma patients. Earlier studies in trauma hemorrhagic shock (T/HS) have documented that splanchnic ischemia leading to gut inflammation and loss of barrier function is an initial triggering event that leads to gut-induced ARDS and MODS. Since sex hormones have been shown to modulate the response to T/HS and proestrous (PE) females are more resistant to T/HS-induced gut and distant organ injury, the goal of our study was to determine the contribution of estrogen receptor (ER)α and ERβ in modulating the protective response of female rats to T/HS-induced gut and lung injury.

Methods/Principal Findings

The incidence of gut and lung injury was assessed in PE and ovariectomized (OVX) female rats subjected to T/HS or trauma sham shock (T/SS) as well as OVX rats that were administered estradiol (E2) or agonists for ERα or ERβ immediately prior to resuscitation. Marked gut and lung injury was observed in OVX rats subjected to T/HS as compared to PE rats or E2-treated OVX rats subjected to T/HS. Both ERα and ERβ agonists were equally effective in limiting T/HS-induced morphologic villous injury and bacterial translocation, whereas the ERβ agonist was more effective than the ERα agonist in limiting T/HS-induced lung injury as determined by histology, Evan''s blue lung permeability, bronchoalevolar fluid/plasma protein ratio and myeloperoxidase levels. Similarly, treatment with either E2 or the ERβ agonist attenuated the induction of the intestinal iNOS response in OVX rats subjected to T/HS whereas the ERα agonist was only partially protective.

Conclusions/Significance

Our study demonstrates that estrogen attenuates T/HS-induced gut and lung injury and that its protective effects are mediated by the activation of ERα, ERβ or both receptors.     

蛋白质跨线粒体膜的运送

线粒体约含１０００种左右蛋白质,其中９８％以上系由细胞核编码,在细胞质核酸体上以前体形式合成之后再运至线粒体并选分定位于各部分,现对定位于基持和内膜的蛋白质的运送途径研究的新进展作一扼要介绍,脱血红素细胞色素ｃ是细胞色素ｃ的前体,它既不含导肽,在线粒体外膜迄今也未发现共受体,对其转运的研究概况也作了评述。