Essential role of IPS-1 in innate immune responses against RNA viruses

IFN-beta promoter stimulator (IPS)-1 was recently identified as an adapter for retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (Mda5), which recognize distinct RNA viruses. Here we show the critical role of IPS-1 in antiviral responses in vivo. IPS-1-deficient mice showed severe defects in both RIG-I- and Mda5-mediated induction of type I interferon and inflammatory cytokines and were susceptible to RNA virus infection. RNA virus-induced interferon regulatory factor-3 and nuclear factor kappaB activation was also impaired in IPS-1-deficient cells. IPS-1, however, was not essential for the responses to either DNA virus or double-stranded B-DNA. Thus, IPS-1 is the sole adapter in both RIG-I and Mda5 signaling that mediates effective responses against a variety of RNA viruses.     

Spred-2 suppresses aorta-gonad-mesonephros hematopoiesis by inhibiting MAP kinase activation

In midgestation mouse embryos, the aorta-gonad-mesonephros (AGM) region generates hematopoietic stem cells and definitive hematopoiesis is regulated by cell-cell interaction and signaling molecules. We showed that a Ras/mitogen-activated protein (MAP) kinase signaling-specific inhibitor and a dominant negative mutant Ras blocked the production of CD45+ hematopoietic cells in embryonic day 11.5 AGM culture, indicating an essential role for the MAP kinase pathway in AGM hematopoiesis. Overexpression of the Ras/MAP kinase pathway regulator, Spred-2, in the AGM culture significantly reduced the number of CD45+ cells. In contrast, production of CD45+ cells from the AGM region of Spred-2-null mice was up-regulated as compared with wild-type littermates. Furthermore, Spred-2-deficient mice exhibited elevated hematopoietic colony formation from vascular endothelial-cadherin+ cells. These data indicate that Spred-2 functions as a negative regulator of AGM hematopoiesis by inhibiting hematopoietic cytokine signaling.     

B cells enhance early innate immune responses during bacterial sepsis

Microbes activate pattern recognition receptors to initiate adaptive immunity. T cells affect early innate inflammatory responses to viral infection, but both activation and suppression have been demonstrated. We identify a novel role for B cells in the early innate immune response during bacterial sepsis. We demonstrate that Rag1(-/-) mice display deficient early inflammatory responses and reduced survival during sepsis. Interestingly, B cell-deficient or anti-CD20 B cell-depleted mice, but not α/β T cell-deficient mice, display decreased inflammatory cytokine and chemokine production and reduced survival after sepsis. Both treatment of B cell-deficient mice with serum from wild-type (WT) mice and repletion of Rag1(-/-) mice with B cells improves sepsis survival, suggesting antibody-independent and antibody-dependent roles for B cells in the outcome to sepsis. During sepsis, marginal zone and follicular B cells are activated through type I interferon (IFN-I) receptor (IFN-α/β receptor [IFNAR]), and repleting Rag1(-/-) mice with WT, but not IFNAR(-/-), B cells improves IFN-I-dependent and -independent early cytokine responses. Repleting B cell-deficient mice with the IFN-I-dependent chemokine, CXCL10 was also sufficient to improve sepsis survival. This study identifies a novel role for IFN-I-activated B cells in protective early innate immune responses during bacterial sepsis.     

An essential role for lipopolysaccharide-binding protein in pulmonary innate immune responses

Lipopolysaccharide (LPS)-binding protein (LBP) greatly facilitates LPS activation of monocytic cells through the CD14 receptor, triggering activation of innate immune responses. An acute phase protein, LBP is produced predominantly by the liver; however, we and others have shown that LBP is produced extrahepatically in multiple locations, including the lung. The importance of LBP in the lung has remained unclear. LBP may make the host more acutely sensitive to LPS and development of septic complications; alternatively, it may be protective, aiding in detection, opsonization, and killing of bacteria. Our objective was to determine the role LBP plays in local pulmonary immune defenses to bacterial challenge. LBP knockout mice and age-matched C57BL/6 wild-type controls were challenged with direct intratracheal inoculation of Klebsiella pneumoniae. We observed a significant increase in mortality, earlier onset of bacteremia, and greater pulmonary bacterial loads in LBP knockout mice compared with controls. Total lung myeloperoxidase (MPO) activity, neutrophil recruitment to the alveolar space, and levels of KC--a chemokine involved in neutrophil recruitment--in bronchoalveolar lavage (BAL) fluid and lung homogenates were found to be significantly diminished in knockout mice compared with controls. Together, our findings suggest that LBP is essential in local pulmonary innate immune responses against bacteria.     

The molecular adapter Carma1 controls entry of IkappaB kinase into the central immune synapse

Carma1 (also known as caspase recruitment domain [CARD]11, Bimp3) is a CARD-containing membrane-associated guanylate kinase family protein that plays an essential role in antigen receptor-induced nuclear factor kappaB activation. We investigated the role of Carma1 in the assembly of signaling molecules at the immune synapse using a peptide-specific system. We report that Carma1 is essential for peptide-induced interleukin 2 and interferon gamma production, but dispensable for proliferation in T cells. Recruitment and distribution of T cell receptor, lymphocyte function associated 1, lipid rafts, and protein kinase C (PKC)theta; to central and peripheral immune synapse regions occur normally in Carma1-/- T cells. Carma1 controls entry of IkappaB kinase (IKK) into lipid raft aggregates and the central region of the immune synapse, as well as activation of IKK downstream of PKC. Our data provide the first genetic evidence on a new class of molecular scaffold that controls entry of defined signaling components, IKK, into the central supramolecular activation cluster at T cell-antigen-presenting cell interfaces without having any apparent effect on the overall organization and formation of immune synapses.     

Extracellular vesicle– and particle-mediated communication shapes innate and adaptive immune responses

Intercellular communication among immune cells is vital for the coordination of proper immune responses. Extracellular vesicles and particles (EVPs) act as messengers in intercellular communication, with important consequences for target cell and organ physiology in both health and disease. Under normal physiological conditions, immune cell–derived EVPs participate in immune responses by regulating innate and adaptive immune responses. EVPs play a major role in antigen presentation and immune activation. On the other hand, immune cell–derived EVPs exert immunosuppressive and regulatory effects. Consequently, EVPs may contribute to pathological conditions, such as autoimmune and inflammatory diseases, graft rejection, and cancer progression and metastasis. Here, we provide an overview of the role of EVPs in immune homeostasis and pathophysiology, with a particular focus on their contribution to innate and adaptive immunity and their potential use for immunotherapies.     

Effect of naloxone on immune responses after hemorrhagic shock

OBJECTIVE: To determine whether naloxone administration after hemorrhagic shock has any beneficial or deleterious effect on immune responses. BACKGROUND DATA: Hemorrhagic shock is known to produce immunodepression in both humans and experimental animals. Although studies suggest that endogenous opioids play a role in immune regulation in adverse circulatory conditions, it remains controversial whether these opioids exert beneficial or detrimental effects on immunity after shock. Moreover, little information is available concerning the effects of opioid receptor blockade using naloxone on cell-mediated immunity and endocrine responses after shock. METHODS: Male C3H/HeN mice (25 g) were bled to and maintained at a mean arterial blood pressure of 35+/-5 mm Hg for 1 hr. The shed blood was then returned along with lactated Ringer's solution (two times the shed blood volume) to provide fluid resuscitation. The animals were randomized to receive either naloxone (1 mg/kg i.v.) or an equal volume of vehicle (saline) after the shed blood was returned, i.e., immediately before crystalloid resuscitation, and were killed at 2 hrs after resuscitation to obtain splenocytes, macrophages (peritoneal and splenic), and blood. MEASUREMENTS AND MAIN RESULTS: Bioassays revealed significantly decreased release of all studied interleukins (interleukins-1, -2, -3, and -6) by peritoneal and splenic macrophages as well as significantly decreased splenocyte proliferative capacity after shock in vehicle-treated mice. Naloxone administration after hemorrhage resulted in either similar or even more decreased levels of interleukin release compared with vehicle-treated hemorrhaged mice. Significantly increased plasma corticosterone concentrations were observed in vehicle-treated animals compared with control animals. Naloxone administration did not have any significant effects on corticosterone plasma concentrations after hemorrhage. CONCLUSIONS: These findings indicate the importance of the endogenous opioid system for the maintenance of immunity in adverse circulatory conditions, i.e., hemorrhage. Although additional studies involving different doses and/or times of naloxone administration may provide different results, the present findings raise the concern that naloxone administration in the traumatized host may have deleterious effects because it decreases peritoneal macrophage and splenic immune functions.     

Immunodominant liver-specific expression suppresses transgene-directed immune responses in murine pompe disease

Pompe disease can be treated effectively, if immune tolerance to enzyme replacement therapy (ERT) with acid α-glucosidase (GAA) is present. An adeno-associated viral (AAV) vector carrying a liver-specific regulatory cassette to drive GAA expression (AAV-LSPhGAA) established immune tolerance in GAA knockout (KO) mice, whereas ubiquitous expression with AAV-CBhGAA provoked immune responses. Therefore, we investigated the hypothesis that immune tolerance induced by hepatic-restricted expression was dominant. AAV-LSPhGAA and AAV-CBhGAA were administered singly or in combination to groups of adult GAA-KO mice, and AAV-LSPhGAA induced immune tolerance even in combination with AAV-CBhGAA. The dual vector approach to GAA expression improved biochemical correction of GAA deficiency and glycogen accumulations at 18 weeks, and improved motor function testing including wire-hang and grip-strength testing. The greatest efficacy was demonstrated by dual vector administration, when both vectors were pseudotyped as AAV8. T cells from mice injected with AAV-LSPhGAA failed to proliferate at all after an immune challenge with GAA and adjuvant, whereas mock-treated GAA-KO mice mounted vigorous T cell proliferation. Unlike AAV-LSPhGAA, AAV-CBhGAA induced selective cytokine and chemokine expression in liver and spleen after the immune challenge. AAV-CBhGAA transduced dendritic cells and expressed high-level GAA, whereas AAV-LSPhGAA failed to express GAA in dendritic cells. The level of transduction in liver was much higher after dual AAV8 vector administration at 18 weeks, in comparison with either vector alone. Dual vector administration failed to provoke antibody formation in response to GAA expression with AAV-CBhGAA; however, hepatic-restricted expression from dual vector expression did not prevent antibody formation after a strong immune challenge with GAA and adjuvant. The relevance of immune tolerance to gene therapy in Pompe disease indicates that hepatic expression might best be combined with nonhepatic expression, achieving the benefits of ubiquitous expression in addition to evading deleterious immune responses.     

Molecules from Staphylococcus aureus that bind CD14 and stimulate innate immune responses

Mammals mount a rapid inflammatory response to gram-negative bacteria by recognizing lipopolysaccharide (LPS, endotoxin). LPS binds to CD14, and the resulting LPS-CD14 complex induces synthesis of cytokines and up-regulation of adhesion molecules in a variety of cell types. Gram- positive bacteria provoke a very similar inflammatory response, but the molecules that provoke innate responses to these bacteria have not been defined. Here we show that protein-free, phenol extracts of Staphylococcus aureus contain a minor component that stimulates adhesion of neutrophils and cytokine production in monocytes and in the astrocytoma cell line, U373. Responses to this component do not absolutely require CD14, but addition of soluble CD14 enhances sensitivity of U373 cells by up to 100-fold, and blocking CD14 on monocytes decreases sensitivity nearly 1,000-fold. Deletion of residues 57-64 of CD14, which are required for responses to LPS, also eliminates CD14-dependent responses to S. aureus molecules. The stimulatory component of S. aureus binds CD14 and blocks binding of radioactive LPS. Unlike LPS, the activity of S. aureus molecules was neither enhanced by LPS binding protein nor inhibited by bactericidal/permeability increasing protein. The active factor in extracts of S. aureus is also structurally and functionally distinct from the abundant species known as lipoteichoic acid (LTA). Cell- stimulating activity fractionates differently from LTA on a reverse- phase column, pure LTA fails to stimulate cells, and LTA antagonizes the action of LPS in assays of IL-6 production. These studies suggest that mammals may use CD14 in innate responses to both gram-negative and gram-positive bacteria, and that gram-positive bacteria may contain an apparently unique, CD14-binding species that initiates cellular responses.     

Increased MerTK expression in circulating innate immune cells of patients with septic shock

Purpose

A new pathway of three protein tyrosine kinase receptors, namely, the TAM receptor family [Tyro-3, Axl and Mer tyrosine kinase (MerTK)], has recently been described to negatively control immune responses. The objective of this prospective, observational, clinical study was to investigate the expression patterns of TAM receptors in circulating white blood cells collected from patients with septic shock.

Methods

The expression of TAM receptors was measured by flow cytometry in circulating leukocytes from patients with septic shock sampled on days (D) 1–2 (n = 47) and D3–4 (n = 37) after the onset of shock, severe trauma patients at D1–2 after trauma (n = 51) and healthy individuals (n = 23).

Results

On D1–2 after injury, MerTK was overexpressed in monocytes and neutrophils collected from patients with septic shock in comparison with those collected from healthy volunteers and trauma patients. This phenomenon was also observed for mRNA. Conversely, the expression of Tyro-3 and Axl was higher in monocytes from trauma patients versus healthy volunteers or those in septic shock. MerTK expression between D1–2 and D3–4 remained elevated in patients suffering from septic shock who died or developed an intensive care unit-acquired infection, whereas it decreased in patients who recovered uneventfully. This in vivo observed expression pattern was reproduced ex vivo after the incubation of healthy volunteer cells with plasma from septic shock or trauma patients.

Conclusions

MerTK expression in circulating innate immune cells is increased in patients with septic shock in comparison with healthy volunteers and trauma patients. Persistent MerTK overexpression after septic shock is associated with adverse outcome. The role of this family of receptors in the pathophysiology of injury-induced immune dysfunctions deserves to be specifically investigated.     

Bite of the wolf: innate immune responses propagate autoimmunity in lupus

The etiopathogenesis of systemic lupus erythematosus (SLE), a clinically heterogeneous multisystemic syndrome that derives its name from the initial characterization of facial lesions that resemble the bite of a wolf, is considered a complex, multifactorial interplay between underlying genetic susceptibility factors and the environment. Prominent pathogenic factors include the induction of aberrant cell death pathways coupled with defective cell death clearance mechanisms that promote excessive externalization of modified cellular and nuclear debris with subsequent loss of tolerance to a wide variety of autoantigens and innate and adaptive immune dysregulation. While abnormalities in adaptive immunity are well recognized and are key to the pathogenesis of SLE, recent findings have emphasized fundamental roles of the innate immune system in the initiation and propagation of autoimmunity and the development of organ damage in this disease. This Review focuses on recent discoveries regarding the role of components of the innate immune system, specifically neutrophils and interferons, in promoting various aspects of lupus pathogenesis, with potential implications for novel therapeutic strategies.     

Atherosclerosis and innate immune signaling

Atherosclerosis, the leading cause of death in developed countries, is characterized by chronic inflammation in the artery wall. It has been appreciated for decades that this disease is linked to hypercholesterolemia and the accumulation of macrophages in the artery wall, yet the exact mechanisms underlying this inflammatory process remain unclear. The role of innate and adaptive immune responses in the pathogenesis of atherosclerosis has been an area of intense study. It now appears that activation of innate immune signaling pathways designed to protect us from microbes may be responsible for initiating and feeding the chronic inflammatory cascade that characterizes this disease. In this review, we discuss the recent identification of Toll-like receptors and their downstream signaling pathways as critical contributors to atherosclerosis. Unraveling the contribution of individual Toll-like receptors and identifying the ligands that activate these pathways will be a central focus of atherosclerosis research in the next few years. The involvement of these pathways in atherogenesis will not only open up new avenues of investigation, but it also provides new targets for therapeutic manipulation that could ameliorate the atherosclerotic inflammatory response directly.     

Effect of gender and sex hormones on immune responses following shock

Several clinical and experimental studies show a gender dimorphism of the immune and organ responsiveness in the susceptibility to and morbidity from shock, trauma, and sepsis. In this respect, cell-mediated immune responses are depressed in males after trauma-hemorrhage, whereas they are unchanged or enhanced in females. Sex hormones contribute to this gender-specific immune response after adverse circulatory conditions. Specifically, studies indicate that androgens are responsible for the immunodepression after trauma-hemorrhage in males. In contrast, female sex steroids seem to exhibit immunoprotective properties after trauma and severe blood loss, because administration of estrogen prevents the androgen-induced immunodepression in castrated male mice. Nonetheless, the precise underlying mechanisms for these immunomodulatory effects of sex steroids after shock remain unknown. Although testosterone depletion, testosterone receptor antagonism, or estrogen treatment has been shown to prevent the depression of immune functions after trauma-hemorrhage, it remains to be established whether differences in the testosterone-estradiol ratio are responsible for the immune dysfunction. Furthermore, sex hormone receptors have been identified on various immune cells, suggesting direct effects. Thus, the immunomodulatory properties of sex hormones after trauma-hemorrhage might represent novel therapeutic strategies for the treatment of immunodepression in trauma patients.     

Mycobacterium tuberculosis controls host innate immune activation through cyclopropane modification of a glycolipid effector molecule

Mycobacterium tuberculosis (Mtb) infection remains a global health crisis. Recent genetic evidence implicates specific cell envelope lipids in Mtb pathogenesis, but it is unclear whether these cell envelope compounds affect pathogenesis through a structural role in the cell wall or as pathogenesis effectors that interact directly with host cells. Here we show that cyclopropane modification of the Mtb cell envelope glycolipid trehalose dimycolate (TDM) is critical for Mtb growth during the first week of infection in mice. In addition, TDM modification by the cyclopropane synthase pcaA was both necessary and sufficient for proinflammatory activation of macrophages during early infection. Purified TDM isolated from a cyclopropane-deficient pcaA mutant was hypoinflammatory for macrophages and induced less severe granulomatous inflammation in mice, demonstrating that the fine structure of this glycolipid was critical to its proinflammatory activity. These results established the fine structure of lipids contained in the Mtb cell envelope as direct effectors of pathogenesis and identified temporal control of host immune activation through cyclopropane modification of TDM as a critical pathogenic strategy of Mtb.     

血红素氧合酶-1对内毒素休克大鼠肺组织的保护功能

目的　探讨血红素氧合酶是否对内毒素休克大鼠的肺组织有保护作用。方法　将 4 0只健康清洁级Sprague Dawley大鼠随机分为对照组 (C组 ) ,内毒素休克组 (ES组 ) ,内毒素休克 +ZnPP IX组 (EZ组 ) ,ZnPP IX组 (Z组 )。检测肺组织含水率、MDA含量和SOD活性及HO 1mRNA、HO 2mRNA、HO 1和HO 2蛋白水平的变化。结果　①ES组大鼠肺组织含水率及MDA明显低于EZ组 (P值均小于 0 0 5 ) ,但其SOD明显高于EZ组 (P <0 0 5 ) ;②EZ组大鼠其肺组织组织内HO 1mRNA表达水平及HO 1蛋白水平明显低于ES组 (P值均小于 0 0 5 ) ;而各组间肺组织组织内HO 2mRNA表达水平及HO 2蛋白水平均无显著性差异(P值均大于 0 0 5 )。结论　内毒素休克大鼠其肺组织内的HO 1可能对其发挥着保护作用     

Morphine suppresses primary humoral immune responses by a predominantly indirect mechanism.

Morphine suppresses humoral immune responses, causes thymic hypoplasia and suppresses NK (natural killer) activity in animal models. There is evidence that thymic hypoplasia and NK suppression are predominantly mediated by indirect mechanisms. The mechanism of morphine-induced humoral immunosuppression is less certain. Recent reports suggest that morphine and other opioids can directly act on cells of the immune system to suppress the generation of antibody-forming cells (AFC) in Mishell-Dutton cultures. The present study was designed to assess the roles of direct and indirect mechanisms in morphine-induced suppression of humoral immunity. Splenocytes from mice treated with morphine by s.c. implantation of a slow-release 75 mg pellet were dysfunctional in Mishell-Dutton cultures. Exposure to morphine in vivo for 12 or 24 hr caused significant suppression of the AFC production stimulated by sheep erythrocytes in Mishell-Dutton cultures. In contrast, direct addition of morphine or the kappa selective opioid agonist U50,488H to Mishell-Dutton cultures under a variety of conditions had little or no effect on AFC generation. These results indicate that suppression of humoral responses by morphine is not primarily mediated by direct action of morphine on the immune system. Suppression of AFC responses by administration of morphine in vivo was substantially blocked by treating mice with the glucocorticoid antagonist RU 38486, suggesting that glucocorticoids may be involved in the indirect mechanism by which morphine causes splenocyte dysfunction.     

The immunoreceptor adapter protein DAP12 suppresses B lymphocyte-driven adaptive immune responses

DAP12, an immunoreceptor tyrosine-based activation motif-bearing adapter protein, is involved in innate immunity mediated by natural killer cells and myeloid cells. We show that DAP12-deficient mouse B cells and B cells from a patient with Nasu-Hakola disease, a recessive genetic disorder resulting from loss of DAP12, showed enhanced proliferation after stimulation with anti-IgM or CpG. Myeloid-associated immunoglobulin-like receptor (MAIR) II (Cd300d) is a DAP12-associated immune receptor. Like DAP12-deficient B cells, MAIR-II-deficient B cells were hyperresponsive. Expression of a chimeric receptor composed of the MAIR-II extracellular domain directly coupled to DAP12 into the DAP12-deficient or MAIR-II-deficient B cells suppressed B cell receptor (BCR)-mediated proliferation. The chimeric MAIR-II-DAP12 receptor recruited the SH2 domain-containing protein tyrosine phosphatase 1 (SHP-1) after BCR stimulation. DAP12-deficient mice showed elevated serum antibodies against self-antigens and enhanced humoral immune responses against T cell-dependent and T cell-independent antigens. Thus, DAP12-coupled MAIR-II negatively regulates B cell-mediated adaptive immune responses.     

Elimination of innate immune responses and liver inflammation by PEGylation of adenoviral vectors and methylprednisolone

Improvement of the therapeutic index of adenoviral gene transfer requires the development of strategies to abrogate adenoviral capsid-induced inflammation and cytokine production. The effect of monomethoxypolyethylene glycol (MPEG) conjugation to adenoviral vectors and of methylprednisolone (MP) on innate immunity, liver inflammation, and thrombocyte counts was evaluated after transfer of 1011 particles of E1/E3/E4- deleted adenoviral vector expressing human apolipoprotein A-I (apoA-I). Gene transfer with unPEGylated vectors induced peak interleukin-6 (IL-6) plasma levels that were 66-fold above baseline levels in C57BL/6 mice. PEGylation combined with 4 mg of MP 6 hr before and at the time of gene transfer suppressed IL-6 plasma levels to baseline values at all time points. This combination resulted in 24-, 28-, 5.9-, 42-, 26-, and 2.5- fold reduced mRNA expression in the liver of monocyte chemoattractant protein-1, macrophage inflammatory protein-2, interferon-inducible protein-10, macrophage inflammatory protein-1 beta, lipopolysaccharide-induced CXC chemokine, and keratinocyte-derived chemokine, respectively; abrogated neutrophil infiltration in the liver; and reduced alanine aminotransferase levels. PEGylation reduced vector uptake in the spleen and in nonparenchymal liver cells. PEGylation also inhibited the development of thrombocytopenia. In conclusion, PEGylation of adenoviral vectors combined with MP administration improves the therapeutic index of adenoviral gene transfer.     

Bacterial challenge stimulates innate immune responses in extra-embryonic tissues of tobacco hornworm eggs

Innate immunity protects juvenile and adult vertebrates and invertebrates against potential pathogens; however, it is unknown when developing embryos become immune competent and just how they are guarded from infection. To address these questions, we studied the effect of immune challenge on early stage eggs of the tobacco hornworm, Manduca sexta. We detected many immune-related proteins and mRNAs in naive eggs. Upon immune challenge, antimicrobial protein genes were up-regulated, and antibacterial activity increased. Antimicrobial protein mRNAs and lysozyme were present in the extra-embryonic tissues of immune-challenged eggs; in addition, melanization in response to bacteria occurred in the yolk but not embryonic tissues. We conclude that the extra-embryonic tissues of early stage M. sexta eggs are immune competent and likely protect the developing embryo from infection. We suggest that innate immune responses of extra-embryonic tissues may be a common mechanism for protecting early embryos.     

内毒素休克兔循环血一氧化氮和内皮素—1的动态观察

目的：观察内毒素休克兔循环血一氧化氮（ＮＯ）和内皮素１（ＥＴ１）的动态变化，进一步探讨内毒素休克的发病机制。方法：新西兰白兔２５只，经颈外静脉一次性注射大肠杆菌内毒素（ＬＰＳ，Ｅ．ｃｏｌｉＯ１１１Ｂ４８．０×１０９ｃｆｕ／ｋｇ），观察平均动脉压（ＭＡＰ）、血浆肿瘤坏死因子α（ＴＮＦα）、ＮＯ－２和ＥＴ１的动态变化，以及组织一氧化氮合酶（ＮＯＳ）活性与器官功能变化。结果：一次性注射ＬＰＳ后，ＭＡＰ呈双相下降；血浆ＴＮＦα活性变化呈陡直的单峰曲线；ＮＯ－２含量于实验后３０分钟迅速增高，实验后６小时达峰值，实验后２４小时仍高于实验前；实验后２４小时心脏组织中ＮＯＳ活性明显高于肝、肺和肾组织；血浆ＥＴ１含量呈双相增高（０．５小时、８小时），实验后２４小时仍高于注射前；血浆ＮＯ－２与ＥＴ１含量呈显著正相关；肝、肾功能损害进行性加重。结论：一次性静注ＬＰＳ后，ＮＯ的生成迅速而持久地增加，ＥＴ１的合成与释放则呈双相增加。ＮＯ与ＥＴ呈显著正相关