淋浆对内毒素休克大鼠微循环障碍的干预作用

目的：探讨淋浆对内毒素休克的干预作用及其机制。方法：Wistar雄性大鼠60只,随机分为对照组、模型组和淋浆组,以颈静脉注射LPS（15 mg/kg）复制内毒素休克模型,造模15 min后,淋浆组自颈静脉注射正常淋浆（占全血量1/15）,观察对平均动脉血压（MAP）、回肠下段肠系膜微循环、细静脉壁白细胞粘附数、血浆P-选择素和细胞间粘附分子（ICAM-1）含量的影响。结果：正常淋浆可防止内毒素休克的MAP进行性下降,解除肠系膜微血管的病理性缩窄,减少白细胞在细静脉壁的粘附,改善微循环的流态,降低血浆P-选择素和ICAM-1的水平。结论：小量正常淋浆对LPS攻击导致内毒素休克的微循环障碍和低血压均有良好的干预作用,其机制与减少细胞粘附分子生成有关。     

Toll样受体4(TLR4)基因剔除小鼠构建及初步表型分析

目的 利用CRISPR/Cas9技术构建Toll样受体4(TLR4)基因敲除小鼠模型,并观察突变小鼠对革兰氏阴性细菌脂多糖(LPS)刺激响应的变化。方法 针对TLR4基因外显子2设计并合成1对sgRNA片段,与编码Cas9的mRNA混合后通过受精卵显微注射方法,建立TLR4基因敲除小鼠,通过繁育获得基因敲除纯合子小鼠(TLR4^-/-小鼠);通过LPS刺激,分析TLR4^-/-小鼠对炎症应激的反应情况,并在分子和病理水平上和野生型对照(WT)进行比较。结果 PCR及测序检测表明TLR4基因外显子2在小鼠基因中被成功敲除;给予LPS刺激后,IL1β、IL6、MyD88、iNOS及TNFa等炎症因子的表达在野生型小鼠的心、肝和肺组织中显著上调,而在TLR4^-/-小鼠中则几乎没有变化;血生化指标显示LPS刺激后WT小鼠血清中的尿素(Urea)和肌酐(Cre)水平显著升高,而TLR4^-/-小鼠刺激前后无显著变化,病理分析同样发现TLR4^-/-小鼠能够抵抗LPS对肾组织的损伤。结论 利用CRISPR/Cas9技术成功构建了TLR4基因剔除小鼠模型,TLR4的缺失能够降低IL1β、IL6、MyD88、iNOS及TNFa炎症因子对LPS刺激的响应,抑制LPS引起的炎症反应及对组织的损伤。     

家鸽小肠绒毛微血管铸型的扫描电镜观察

用扫描电镜观察了ＡＢＳ丁酮溶液灌注的家鸽小肠绒告发同血管构筑情况。家鸽小肠绒毛血管丛由输入沁动脉、毛细血管网和输出小静脉组成,小肠绒毛血管丰富,并相到吻合成单层密集网;办入小动脉既可从肠腺周围血管丛发出,也可直接由粘膜下去一发出,绒毛下部血管表现为微直血管形态,可能部分具有门静脉性质。     

HSF1基因剔除对HSR抗内毒素血症的影响

利用内毒素(LPS)血症小鼠模型,观察HSF1基因剔除对热休克反应(HSR)保护作用的影响.采用腹腔注射LPS建立内毒素血症小鼠模型,HSR采用肛温42℃维持15 min,室温恢复24 h,利用RT-PCR、苏木素-伊红(HE)染色、丙二醛测定以及死亡率,计算和分析重要脏器组织中炎症介质基因的表达、脏器损伤程度及小鼠存活率.注射LPS 15mg/kg 72 h后HSR LPS(HSF1 / )组存活率(7/15)显著高于LPS(HSF1 / )组(0/15)、LPS(HSF1-/-)组(0/14)和HSR LPS(HSF1-/-)组(0/14),而注射LPS 14 mg/kg 72 h后,LPS(HSF1 / )组存活率(5/15)显著高于LPS(HSF1-/-)组(0/13)和HSR LPS(HSF1-/-)组(0/13).在注射LPS 12 h后LPS(HSF1 / )组、LPS(HSF1-/-)组和HSR LPS(HSF1-/-)组的心、肺组织丙二醛含量显著升高,但HSR LPS(HSF1 / )组不升高.肺组织炎症介质基因IL-IB、IL-6、TNF-α、CCL-2、SOCS3、MCSF、GCSF、IL-15在LPS(HSF1-/-)组和LPS(HSF1 / )组表达上调,HSR LPS(HSF1-/-)组除IL-15较低外其他上调更甚,HSR LPS(HSF1 / )组除IL-1β和TNF-α较高外其他显著下调.注射LPS后LPS(HSF1 / )组和LPS(HSF1-/-)组的肺、肝、肾病理形态改变明显,HSR LPS(HSF1 / )组改变较轻,HSR LPS(HSF1-/-)组改变更加严重.HSF1基因剔除能显著消减HSR对内毒素血症小鼠的保护作用.     

脂多糖诱导小鼠脏器中胞间粘附分子-1的表达

为研究脂多糖（lipopolysaccharide,LPS)诱导的内毒素休克小鼠多种脏器中胞间粘附分子-1（intercellu-lar adhesion molecule-1,ICAM-1)表达的差异。用5mg/kgLPS腹腔注射小鼠后,分别采用Western blotting和RT-PCR法检测组织中ICAM-1蛋白和mRNA的表达情况,结果显示,在正常小鼠,ICAM-1蛋白和mRNA的表达在肺中最多,其次是脾脏,在肾脏和肠有少量表达,在肝脏和心脏中未能检出,LPS腹腔注射后6h可诱导小鼠发生内毒素休克,此时,ICAM-1蛋白表达仍以在肺中最多,在肝、脾、心、肾和肠依次减少;其中在肺,肾和脾分别比正常时增加4.5、3.0和1.5倍,而且在正常时不能检出的肝和心中呈现阳性,但在肠中则变化不大,脏器中ICAM-1mRNA亦相应显著增加,上述结果表明,在LPS诱导的内毒素休克小鼠的多种脏器中ICAM-1蛋白和mRNA表达显著增加,脏器间ICAM-1表达上调的差异可能带来内毒素休克时脏器的不同易伤性,抑制ICAM-1的表达可能对内毒素休克的防治有重要的意义。     

八肽胆囊收缩素对内毒素休克时海马损伤的影响及其机制初探

目的：观察八肽胆囊收缩素（CCK-8）对内毒素休克（ES）时海马损伤的影响,并探讨其可能的作用机制。方法：将日本大耳白兔经静脉注入内毒素的主要活性成分脂多糖（LPS,8mg／kg）复制ES模型。动物（32只）随机分为对照组、LPS组、CCK-8＋LPS组和非特异性CCK受体拮抗剂丙谷胺（Pro）＋LPS组（n=8）。监测平均动脉压（MAP）的变化,光、电镜观察海马的组织形态学改变,比色法检测海马NOS和SOD活性、N0和MDA含量的改变．用SD大鼠（12只,同上复制模型及分组）以免疫组织化学染色法观察海马iNOS和nNOS表达的变化。结果：与对照组相比,注入LPS后出现MAP显著而持续下降（P〈0．01）;海马部位神经元损伤明显;iNOS和nNOS表达增强,NOS活性、NO和MDA含量显著升高（P〈0．05、P〈0．01和P〈0．01）,SOD活性则降低（P〈0．01）。预先注入CCK-8可明显减轻上述变化,预先注入Pro则加剧以上变化。结论：CCK-8可减轻ES时脑内海马部位的损伤。其机制可能与其抗氧化作用和抑制NO的过量生成有关。     

微循环的结构与生理特点

微循环(Microcirculation)是指小动脉与小静脉之间毛细血管的血液循环。其主要组成部分是毛细血管,一般肉眼看不到,须放大50倍以上方可看清。放在150—200倍显微镜下可看到血管内情况。实验观察可取蛙一只,用20％氨基甲酸乙酯(脲酯乌拉坦)进行皮下淋巴囊注射(2毫克/克体重)将其麻醉。然后将蛙固定在蛙板上,在下腹部旁侧剪一长切口,拉出一段小肠并将肠系膜展开,用大头针固定于蛙板上,在低倍显微镜下即可分辨循环的小动脉、小静脉及毛细血管三部分。镜下可见,小动脉内血流     

内源性一氧化氮在内毒素引起的肺动脉高压和肺损伤中的作用

本实验观察了家兔静脉内注入内毒素的主要成分脂多糖(LPS)后平均动脉血压(MAP)、肺动脉压(PAP)及入、出肺血NO含量的变化,并观察了静脉内预注入NO生成抑制剂Nω-硝基-L-精氨酸(L-NNA)及诱生型NO生成抑制剂氨基胍(AG)后PAP和肺损伤的变化.结果观察到:家兔LPS注入后,MAP均明显下降,LPS注入后0.5、1、1.5、2h PAP明显增高(P<0.05).LPS注入后PAP的高峰期(1h)入肺血NO含量明显降低,出肺血NO无明显变化.与对照组相比,LPS注入后3h出肺血NO含量和5h入、出肺血NO含量均明显增多.相关分析表明,兔LPS注入前和LPS注入后1h PAP与入肺血NO含量呈明显的负相关,而LPS注入后 3h和5h两者相关不明显.静脉预注入L-NNA后,LPS处理组的动物PAP明显增高,入、出肺血丙二醛(MDA)含量也明显增高,动物生存率明显降低.肺组织光镜下可见肺萎陷和小血管淤血加重,白细胞明显增加.静脉预注入AG后,LPS处理组的动物MAP在3～5h明显增高,此时PAP无明显改变,但5h时血中MDA含量明显减低,5h时与LPS组相比肺萎陷和小血管淤血减轻,白细胞也明显减少.以上结果提示,内毒素入血后较早期阶段可出现PAP的升高,此时入肺血NO的减少是参与肺动脉压增高(PAH)的机制之一.家兔内毒素进入血后较早期阶段NO对减轻内毒素引起的PAH和肺损伤起重要作用,而较晚的时期当诱生型NO合酶(iNOS)诱生后释放的NO则参与内毒素引起的肺组织炎症反应和肺损伤.     

创伤后血二胺氧化酶的变化与肠粘膜损伤

探讨创伤感染对肠道屏障功能的影响。以山羊、大鼠手术+失血再灌注+内毒素(LPS),大鼠肠缺血再灌注和犬低温枪伤多种创伤动物为模型,测定血浆二胺氧化酶(DAO)活性,并测定血乳酶、TNF和LPS含量。观察小肠病理形态改变。结果:失血再灌注后血浆DAO水平显著升高,给予内毒素后山羊血DAO水平再度升高。血浆DAO的变化与血乳酸,TNF和LPS变化呈高度相关(r=0.872,0.842和0.817,p<0.01)。光、电镜检查表明肠粘膜损伤,失血再灌注损伤可致肠粘膜屏障功能损伤,测定血浆DAO活性变化对判断小肠粘膜损伤有帮助     

脂多糖模拟肽13L诱导对小鼠内毒素休克的保护反应

为研究LPS 2630表位模拟肽13L是否能诱导抗脂多糖（LPS）抗体的产生、对细菌攻击及内毒素休克的保护性反应,合成了模拟LPS表位的短肽13L．用合成肽13L-蓝载体（blue carrier,BC）交联物免疫Balb／C小鼠,观察小鼠体内抗LPS抗体产生的规律,并观察免疫小鼠细菌感染存活时间,用颈总动脉插管测定技术观察免疫小鼠内毒素休克的血压变化．结果显示,合成肽13L-BSA交联物能与兔抗鼠伤寒和大肠杆菌LPS抗血清及抗鼠伤寒LPS单抗结合,证明短肽13L可模拟LPS的抗原性．用13L-BC交联物免疫可诱发小鼠体内针对大肠杆菌LPS 2630和鼠伤寒沙门氏菌LPS 7261的抗体反应,该反应可被灭活大肠杆菌及两种LPS所加强,其抗体亚类主要为IgG2a,其次为IgG2b与IgM,而IgG1与IgG3含量极低．免疫13L-BC小鼠显示对细菌攻击的抵抗,与免疫BC对照小鼠比较,其存活时间分别为（12&#177;1．3）天和（5．3&#177;0．4）天（P〈0．01）．免疫13L-BC小鼠对静脉注射LPS诱发内毒素休克的保护作用体现在血压下降幅度明显低于对照动物,在LPS 2630攻击后1、2、3及4h时两组动物血压明显差别（P〈0．05、P〈0．01、P〈0．05及P〈0．01）,而LPS 7261攻击后1、2、3及4h时两组动物血压差别则略小于LPS 2630组（P〉0．05、P〈0．05、P〈0．05及P〈0．01）．上述结果证明,LPS表位模拟肽13L交联物免疫小鼠可产生针对细菌攻击及内毒素休克的保护性效应,提示该模拟肽作为LPS交叉保护性疫苗候选的可行性．     

Comparative study of several lymphocyte functions in two strains of mice with different models of endotoxic shock

Previously, the changes in phagocyte functions such as adherence, chemotaxis or TNFalpha production were found to be associated with oxidative stress in endotoxin-induced septic shock. However, in this type of oxidative stress the lymphocyte involvement has rarely been studied. In the present report, we analyzed the above functions in peritoneal lymphocytes from male and female BALB/c mice with a lethal endotoxic shock caused by intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg), male and female Swiss mice with lethal endotoxic shock caused by intraperitoneal injection of LPS (150 and 250 mg/kg, respectively) or non-lethal endotoxic shock (100 mg/kg). In peritoneal lymphocytes obtained at 0, 2, 4, 12 or 24 h after LPS injection, the first two functions of these cells in the immune response, i.e. adherence to tissues and directed migration (chemotaxis), were studied. At 0, 0.5, 1, 1.5, 2, 4, 12 and 24 h after LPS injection, TNFalpha released by lymphocytes was also analyzed. The results show that endotoxic shock increases the adherence and TNFalpha release, and decreases the chemotaxis of peritoneal lymphocytes. These changes were more significant in mice with lethal than with non-lethal endotoxic shock, a fact that confirms the important role of lymphocytes during endotoxic shock.     

Effect of plasma phospholipid transfer protein deficiency on lethal endotoxemia in mice

Lipopolysaccharides (LPS) are components of Gram-negative bacteria. The cellular response from the host to LPS is mediated through stepwise interactions involving the lipopolysaccharide-binding protein (LBP), CD14, and MD-2, which produces the rearrangement of TLR4. In addition to LBP, the lipid transfer/lipopolysaccharide-binding protein gene family includes the phospholipid transfer protein (PLTP). Here we show that the intravascular redistribution of LPS from the plasma lipoprotein-free fraction toward circulating lipoproteins is delayed in PLTP-deficient mice. In agreement with earlier in vitro studies, which predicted the neutralization of the endotoxic properties of LPS when associated with lipoproteins, significant increases in the plasma concentration of proinflammatory cytokines were found in PLTP-deficient as compared with wild type mice. Similar inflammatory damage occurred in tissues from wild type and PLTP-deficient mice 24 h after one single intraperitoneal injection of LPS but with a more severe accumulation of red blood cells in glomeruli of LPS-injected PLTP-deficient mice. Complementary ex vivo experiments on isolated splenocytes from wild type and PLTP-deficient mice further supported the ability of cell-derived PLTP to prevent LPS-mediated inflammation and cytotoxicity when combined with lipoprotein acceptors. Finally, PLTP deficiency in mice led to a significant increase in LPS-induced mortality. It is concluded that increasing circulating levels of PLTP may constitute a new and promising strategy in preventing endotoxic shock.     

Regulation of lipopolysaccharide‐induced inflammatory response and endotoxemia by β‐arrestins

β‐Arrestins are scaffolding proteins implicated as negative regulators of TLR4 signaling in macrophages and fibroblasts. Unexpectedly, we found that β‐arrestin‐1 (β‐arr‐1) and ‐2 knockout (KO) mice are protected from TLR4‐mediated endotoxic shock and lethality. To identify the potential mechanisms involved, we examined the plasma levels of inflammatory cytokines/chemokines in the wild‐type (WT) and β‐arr‐1 and ‐2 KO mice after lipopolysaccharide (LPS, a TLR4 ligand) injection. Consistent with lethality, LPS‐induced inflammatory cytokine levels in the plasma were markedly decreased in both β‐arr‐1 and ‐2 KO, compared to WT mice. To further explore the cellular mechanisms, we obtained splenocytes (separated into CD11^b+ and CD11^b? populations) from WT, β‐arr‐1, and ‐2 KO mice and examined the effect of LPS on cytokine production. Similar to the in vivo observations, LPS‐induced inflammatory cytokines were significantly blocked in both splenocyte populations from the β‐arr‐2 KO compared to the WT mice. This effect in the β‐arr‐1 KO mice, however, was restricted to the CD11^b? splenocytes. Our studies further indicate that regulation of cytokine production by β‐arrestins is likely independent of MAPK and IκBα‐NFκB pathways. Our results, however, suggest that LPS‐induced chromatin modification is dependent on β‐arrestin levels and may be the underlying mechanistic basis for regulation of cytokine levels by β‐arrestins in vivo. Taken together, these results indicate that β‐arr‐1 and ‐2 mediate LPS‐induced cytokine secretion in a cell‐type specific manner and that both β‐arrestins have overlapping but non‐redundant roles in regulating inflammatory cytokine production and endotoxic shock in mice. J. Cell. Physiol. 225: 406–416, 2010. © 2010 Wiley‐Liss, Inc.     

N-acetylcysteine Protects Mice from Lethal Endotoxemia by Regulating the Redox State of Immune Cells

The excessive production of reactive oxygen species (ROS) associated with inflammation leads to oxidative stress, which is involved with the high mortality from several diseases such as endotoxic shock and can be controlled to a certain degree by antioxidants. The immune cells use ROS in order to support their functions and, therefore, need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive ROS production. In the present work, the effect of the administration of the antioxidant N-acetylcysteine (NAC) on the redox state of peritoneal macrophages and lymphocytes from mice with lethal endotoxic shock (100 mg/kg i.p. of lipopolysaccharide, LPS), was studied. In both types of immune cells at 0, 2, 4, 12 and 24 h after LPS injection, an increase of ROS, of the proinflammatory cytokine tumor necrosis factor alpha (TNFα), the lipid peroxidation (malonaldehyde levels, MDA), inducible nitric oxide synthase (iNOS) expression and the oxidized/reduced glutathione (GSSG/GSH) ratio, as well as a decrease of enzymatic antioxidant defenses, such as superoxide dismutase (SOD) and catalase (CAT) activity, was observed. The injection of NAC (150 mg/kg i.p. at 30 min after LPS injection) decreased the ROS, the TNFα the MDA levels, iNOS expression and the GSSG/GSH ratio, and increased the antioxidant defenses in both macrophages and lymphocytes. Moreover, the NAC treatment prevented the activation of nuclear translocation of the nuclear factor κB (NF-κB), which regulates ROS, inflammatory cytokines and antioxidant levels. Our present results provide evidence that both cell types have a relevant role in the pathogenesis of endotoxic shock, and that NAC, by improving the redox state of these immune cells, could increase mouse survival. Thus, antioxidants could offer an alternative treatment of human endotoxic shock.     

N-acetylcysteine protects mice from lethal endotoxemia by regulating the redox state of immune cells

The excessive production of reactive oxygen species (ROS) associated with inflammation leads to oxidative stress, which is involved with the high mortality from several diseases such as endotoxic shock and can be controlled to a certain degree by antioxidants. The immune cells use ROS in order to support their functions and, therefore, need adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive ROS production. In the present work, the effect of the administration of the antioxidant N-acetylcysteine (NAC) on the redox state of peritoneal macrophages and lymphocytes from mice with lethal endotoxic shock (100 mg/kg i.p. of lipopolysaccharide, LPS), was studied. In both types of immune cells at 0, 2, 4, 12 and 24 h after LPS injection, an increase of ROS, of the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha), the lipid peroxidation (malonaldehyde levels, MDA), inducible nitric oxide synthase (iNOS) expression and the oxidized/reduced glutathione (GSSG/GSH) ratio, as well as a decrease of enzymatic antioxidant defenses, such as superoxide dismutase (SOD) and catalase (CAT) activity, was observed. The injection of NAC (150 mg/kg i.p. at 30 min after LPS injection) decreased the ROS, the TNFalpha the MDA levels, iNOS expression and the GSSG/GSH ratio, and increased the antioxidant defenses in both macrophages and lymphocytes. Moreover, the NAC treatment prevented the activation of nuclear translocation of the nuclear factor kappaB (NF-kappaB), which regulates ROS, inflammatory cytokines and antioxidant levels. Our present results provide evidence that both cell types have a relevant role in the pathogenesis of endotoxic shock, and that NAC, by improving the redox state of these immune cells, could increase mouse survival. Thus, antioxidants could offer an alternative treatment of human endotoxic shock.     

Modulation of murine macrophage function by N-acetylcysteine in a model of endotoxic shock

In previous studies we have observed changes in several functions of peritoneal macrophages from BALB/c mice with irreversible endotoxic shock caused by intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg), which were associated with a high production of superoxide anion. Since antioxidants, such as N-acetylcysteine (NAC), are free radical scavengers that improve the immune response, in the present work we have studied different functions of peritoneal macrophages from BALB/c mice suffering the endotoxic shock above indicated and administered N-acetylcysteine (150 mg/kg i.p.) at 30 minutes after LPS injection. In the peritoneal macrophages obtained at 2, 4, 12 and 24 h after LPS injection, the following functions were studied: adherence to substrate, mobility, ingestion of particles, and production of superoxide anion and tumour necrosis factor (TNF alpha). The increase in adherence, ingestion and superoxide anion and TNF alpha production shown by macrophages from animals with endotoxic shock was counteracted by NAC injection. Moreover, the survival time of mice with endotoxic shock was increased in the presence of NAC. These data suggest that NAC, administered intraperitoneally, may be useful for the treatment of irreversible endotoxic shock by modulation of the function of macrophages with decreased superoxide anion and TNF alpha production and concomitant increase of survival time.     

Changes in the superoxide production and other macrophage functions could be related to the mortality of mice with endotoxin-induced oxidative stress

Free radicals and proinflammatory cytokines from phagocytes have been implicated in the pathogenesis of endotoxic shock, a disease with high mortality caused by Gram-negative bacterial endotoxin. In the present study, male BALB/c and Swiss mice received intraperitoneally lipopolysaccharide (LPS) at 100 mg/kg and 150 mg/kg, respectively, that led to a lethal endotoxic shock (100 % of mortality before 30 h). Swiss mice injected with 100 mg/kg, that did not show lethal endotoxic shock, were also studied. Peritoneal macrophages were obtained from animals at 2, 4, 12 or 24 h after injection of LPS or saline (control) solutions. Superoxide anion and tumor necrosis factor (TNFalpha) production were determined in these cells as well as other functions such as adherence capacity, chemotaxis and phagocytosis. The increase in superoxide anion production after endotoxin injection was higher in cells from mice with lethal shock than in those with non-lethal shock. However, the enhancement of TNFalpha production was similar in all cases, although in Swiss mice the highest levels of TNFalpha were observed at 1.5 h after endotoxin injection, while in BALB/c mice they occurred at 2 h after LPS injection. This oxidative stress was also revealed by the other functions analyzed, since adherence to substrate and phagocytosis were stimulated and chemotaxis was decreased after endotoxin injection as compared to controls, the differences being even more significant in animals with lethal shock. These data suggest that these changes, mainly the increased production of free radicals even more than the TNFalpha release, could be involved in mouse mortality caused by LPS.     

Nitric oxide produced via neuronal NOS may impair vasodilatation in septic rat skeletal muscle

Impaired vascular responsiveness in sepsis may lead to maldistribution of blood flow in organs. We hypothesized that increased production of nitric oxide (NO) via inducible nitric oxide synthase (iNOS) mediates the impaired dilation to ACh in sepsis. Using a 24-h cecal ligation and perforation (CLP) model of sepsis, we measured changes in arteriolar diameter and in red blood cell velocity (V(RBC)) in a capillary fed by the arteriole, following application of ACh to terminal arterioles of rat hindlimb muscle. Sepsis attenuated both ACh-stimulated dilation and V(RBC) increase. In control rats, arteriolar pretreatment with the NO donors S-nitroso-N-acetylpenicillamine or sodium nitroprusside reduced diameter and V(RBC) responses to a level that mimicked sepsis. In septic rats, arteriolar pretreatment with the "selective" iNOS blockers aminoguanidine (AG) or S-methylisothiourea sulfate (SMT) restored the responses to the control level. The putative neuronal NOS (nNOS) inhibitor 7-nitroindazole also restored the response toward control. At 24-h post-CLP, muscles showed no reduction of endothelial NOS (eNOS), elevation of nNOS, and, surprisingly, no induction of iNOS protein; calcium-dependent constitutive NOS (eNOS+nNOS) enzyme activity was increased whereas calcium-independent iNOS activity was negligible. We conclude that 1) AG and SMT inhibit nNOS activity in septic skeletal muscle, 2) NO could impair vasodilative responses in control and septic rats, and 3) the source of increased endogenous NO in septic muscle is likely upregulated nNOS rather than iNOS. Thus agents released from the blood vessel milieu (e.g., NO produced by skeletal muscle nNOS) could affect vascular responsiveness.     

TXNIP Deficiency Exacerbates Endotoxic Shock via the Induction of Excessive Nitric Oxide Synthesis

Thioredoxin-interacting protein (TXNIP) has multiple functions, including tumor suppression and involvement in cell proliferation and apoptosis. However, its role in the inflammatory process remains unclear. In this report, we demonstrate that Txnip^−/− mice are significantly more susceptible to lipopolysaccharide (LPS)-induced endotoxic shock. In response to LPS, Txnip^−/− macrophages produced significantly higher levels of nitric oxide (NO) and inducible nitric oxide synthase (iNOS), and an iNOS inhibitor rescued Txnip^−/− mice from endotoxic shock-induced death, demonstrating that NO is a major factor in TXNIP-mediated endotoxic shock. This susceptibility phenotype of Txnip^−/− mice occurred despite reduced IL-1β secretion due to increased S-nitrosylation of NLRP3 compared to wild-type controls. Taken together, these data demonstrate that TXNIP is a novel molecule that links NO synthesis and NLRP3 inflammasome activation during endotoxic shock.