Fluvastatin attenuates severe hemorrhagic shock-induced organ damage in rats

Objectives

Multiple organ dysfunction resulting from hemorrhagic shock (HS) and subsequent resuscitation was mediated by several inflammatory factors such as tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10). The present study was designed to investigate the protective effects of fluvastatin on these mediators after HS in rats.

Methods

The experimental rats were randomly divided into three groups. The vehicle group received only vitamin K without HS, the HS-control group received vitamin K and HS, and the HS-experimental group received both vitamin K and fluvastatin (1 mg/kg) before HS. HS was produced by bleeding from a femoral arterial catheter to remove 60% of total blood volume (6 ml/100 g BW) over 30 min. The mean arterial pressure (MAP) and heart rate (HR) were monitored continuously for 12 h after the start of blood withdrawal. The biochemical parameters, including arterial blood gas, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea nitrogen (BUN), creatinine (Cre), lactic dehydrogenase (LDH), creatine phosphokinase (CPK), and lactate were obtained at 30 min before induction of HS and at 0, 1, 3, 6, 9 and 12 h after HS. Equal volume of normal saline was given to replace blood volume loss. Cytokine levels including TNF-α and IL-10 in serum were measured at 1 h after HS. Kidney, liver, lung and small intestine were removed for pathology examination at 48 h after HS.

Results

HS significantly increased HR, blood GOT, GPT, BUN, Cre, LDH, CPK, lactate, TNF-α and IL-10 levels, and also induced metabolic acidosis and decreased MAP in rats. Pre-treatment with fluvastatin was found to improve survival rate, preserved MAP, decreased the markers of organ injury, suppressed the release of TNF-α and increased IL-10 after HS in rats.

Conclusion

Pre-treatment with fluvastatin can suppress the release of serum TNF-α and can also increase serum IL-10 level to protect HS-induced multi-organ damage in rats.     

Inhibition by terbutaline of nitric oxide and superoxide anion levels of endotoxin-induced organs injury in the anesthetized rat

Despite the fact that septic shock is characterized by a decrease in systemic vascular resistance, the main cause of death is due to multiple organ failure. The organ dysfunction is usually attributed to cell death caused by overproduction of free radicals derived from inflammation. In the host infected by endotoxin (lipopolysaccharide, LPS), the expression and release of proinflammatory tumor necrosis factor-alpha (TNF-alpha) rapidly increases, and the formation of free radicals (e.g., superoxide anion [O2*-] and nitric oxide [NO*] in the present study) are inevitably overproduced. In this study, we present evidence that overall treatment of LPS rats with terbutaline, a beta2-adrenoceptor agonist, attenuates the delayed hypotension and ameliorates the tachycardia. Overproduction of TNF-alpha and NO* (produced by inducible NO synthase [iNOS] examined by Western blot analysis in the lung and the liver) is inhibited by treatment of LPS rats with terbutaline. In addition, treatment of endotoxemic rats with terbutaline also reduces the O2*- levels in the lung and the liver. Terbutaline also improves the liver (assessed by aspartate aminotransferase, alanine aminotransferase, total bilirubin, and albumin/globulin) and kidney (assessed by creatinine and uric acid) dysfunction induced by endotoxin. These findings suggest that the amelioration of circulatory failure and organs injury by terbutaline is associated with its suppression in TNF-alpha, O2*- and NO (via iNOS) production in animals with endotoxic shock.     

Inhibition of matrix metalloproteinases by chemically modified tetracyclines in sepsis

Sepsis precipitates a systemic inflammatory stimulus that causes systemic release of cytokines and sequestration of polymorphonuclear neutrophils, resulting in degranulation of matrix metalloproteinases (MMPs), which causes extracellular matrix basement membrane degradation. One of the important anti-inflammatory properties of tetracyclines is their ability to inhibit MMPs. In this study, we focused on the regulation of MMPs in sepsis and their reduction by treatment with nonantimicrobial chemically modified tetracyclines (CMTs), which retain their anti-inflammatory activity. Sepsis was induced by cecal ligation and puncture (CLP) method. At 24 h and 1 h before CLP, some rats received CMT-3 (25 mg/kg), another group of rats received hydroxamate (H; an inhibitor of MMP; 25 mg/kg), and untreated rats received saline by gavage. At 0 h, 0.5 h, 1.5 h, and 24 h after CLP, blood and liver samples were collected. Plasma and liver MMP-9 by zymography and Western immunoblotting, plasma nitric oxide by measuring nitrate level, plasma glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) by enzymatic method, and liver gelatinase by radiolabeled gelatin lysis assay and 24 h mortality were determined. Plasma MMP-9 (92 kDa), nitrate, and GOT and GPT levels were elevated compared with the time 0 level and reached peak at 1.5 h CLP and remained high for 24 h. Both CMT-3 and H treatment reduced GOT,GPT, 92-kDa gelatinase, and nitrate levels throughout the 24 h. CMT-3 and H are equally effective in sepsis treatment. The 24-h mortality for CLP rats was 30%, whereas pretreatment with CMT-3 and H resulted in 0% mortality. Hepatic MMP-9 and gelatinase activity increased significantly after CLP, and pretreatment with CMT-3 and H inhibited these expressions. These results indicate the beneficial effect of CMT-3 in preventing the increase in GOT, GPT, NO, MMP-9, gelatinase activity, and the ensuing septic shock.     

Mechanisms of increased survival after lipopolysaccharide-induced endotoxic shock in mice consuming olive oil-enriched diet

We examined the impact of dietary fatty acid intake on lipopolysaccharide (LPS)-induced endotoxic shock. C57Bl/6J mice were fed for 6 weeks with a commercial laboratory chow (CC) or with test chows containing 7% (w/w) canola oil (CO), sesame oil (SeO), soybean oil (SO), or virgin olive oil (OO). The increase in body weight and energy consumption were similar for all diets tested. In the sixth week, mice were injected intraperitoneally with 400 microg of bacterial LPS to induce endotoxic shock. LPS induced a massive neutrophil infiltration into the peritoneal cavity and an increase in lipid body (LB) formation in leukocytes recovered from the peritoneal fluid of mice fed with CC, CO, SeO, or SO. In addition, there were increases in prostaglandin E(2) (PGE(2)), leukotriene B4 (LTB(4)), and cytokines IL-6, IL-10, and MCP-1 in peritoneal lavage, as well as in plasma TNF-alpha. In contrast, mice fed with OO exhibited reduced neutrophil accumulation and LB formation, and also had lower levels of PGE(2), LTB(4), MCP-1, and TNF-alpha. All mice fed with CC, CO, SeO, or SO died within 48 to 72 h after LPS injection. Interestingly, mice fed with the OO diet were resistant to endotoxic shock, with 60% survival at 168 h. These data indicate that intake of OO may have a beneficial role, reducing the magnitude of the inflammatory process triggered by endotoxic shock through modulation of LB formation and of the production of inflammatory mediators.     

Low-dose dexamethasone ameliorates circulatory failure and renal dysfunction in conscious rats with endotoxemia

Corticosteroids have long been proposed as a therapeutic adjuvant in septic renal dysfunction because of their anti-inflammatory properties and favorable results from animal experiments. However, some reports suggested the potential for harm associated with the administration of early high-dose corticosteroids in patients with severe sepsis and septic shock. Thus, we examined the effects of low-dose dexamethasone (0.01 and 0.1 mg/kg) on hemodynamics and renal function in conscious rats with endotoxemia. Intravenous injection of rats with endotoxin (E. coli lipopolysaccharide, LPS, 1 mg/kg) caused hypotension, vascular hyporeactivity, and tachycardia as well as renal dysfunction. Circulatory failure and renal dysfunction caused by LPS were significantly attenuated in the dexamethasone 0.1 mg/kg-treated group. The nitric oxide (NO) production in plasma and renal tissue and the iNOS protein expression in the kidney were suppressed by cotreatment of LPS rats with dexamethasone, 0.1 mg/kg. Light microscopy showed that 0.1 mg/kg dexamethasone reduced marked infiltration of neutrophils in renal tissues from LPS rats. Moreover, the survival rate at 18 h was significantly increased in the dexamethasone 0.1 mg/kg-treated group when compared with the LPS group. These results suggest that the beneficial effects of low-dose dexamethasone (0.1 mg/kg) in conscious rats with endotoxic shock are associated with amelioration of circulatory failure and renal dysfunction, and this is attributed to inhibition of NO production.     

Protection against endotoxic shock by bactericidal/permeability-increasing protein in rats.

Bactericidal/permeability-increasing protein (BPI) is a neutrophil primary granule protein that inhibits effects of LPS in vitro. The current study examined the effects of BPI on hemodynamics, mortality, and circulating endotoxin and cytokines in conscious rats with endotoxic shock. Catheters were implanted into the right femoral artery and vein. 1 d later, human recombinant BPI (10 mg/kg) or vehicle was intravenously injected immediately, 30 min, or 2 h after intravenous injection of LPS (7.5 mg/kg). Mean arterial pressure (MAP) and heart rate were monitored and blood was collected before and after injection. BPI given immediately or 30 min after LPS prevented the LPS-induced reduction in MAP at 4-8 h and markedly reduced mortality. BPI given 2 h after LPS injection had no protective effect. BPI treated immediately after LPS reduced the circulating levels of endotoxin and IL-6 but increased the circulating levels of TNF. We propose that BPI exerts its protective effect through a TNF-independent mechanism, by inhibiting endotoxin-stimulated production of IL-6.     

A cell wall component from pathogenic and non-pathogenic gram-positive bacteria (peptidoglycan) synergises with endotoxin to cause the release of tumour necrosis factor-alpha, nitric oxide production, shock, and multiple organ injury/dysfunction in the rat

The incidence of sepsis and septic shock due to gram-positive organisms has increased dramatically over the last two decades. Interestingly, many patients with sepsis/septic shock have both gram-positive and gram-negative bacteria present in the bloodstream and these polymicrobial or "mixed" infections often have a higher mortality than infection due to a single organism. The reason for this observation is unclear. The aim of this study was to investigate whether cell wall fragments from gram-positive and gram-negative bacteria could synergise to cause the release of cytokines, shock, and organ injury/ dysfunction in vivo. Male Wistar rats were anaesthetised and received an intravenous bolus of vehicle (saline), lipopolysaccharide (LPS) from Escherichia coli (0.1 mg/kg), peptidoglycan (Pep G) from Staphylococcus aureus (S10 mg/kg), co-administration of LPS (0.1 mg/kg) and PepG from S. aureus (10 mg/kg), LPS (10 mg/kg), PepG from Bacillus subtilis, or co-administration of LPS and PepG from B. subtilis. Blood pressure and heart rate were monitored for 6 h before plasma samples were taken for the measurement of TNF-alpha, total nitrite, and biochemical indices of organ injury. Peptidoglycan from both pathogenic (S. aureus) and non-pathogenic (B. subtilis) gram-positive bacteria synergised with endotoxin to cause formation of TNF-alpha, nitrite, shock, and organ injury. Synergism between PepG and LPS may partly explain the high mortality associated with mixed bacterial infections, as well as the deleterious effects of translocation of bacteria, or their cell wall components from the gut lumen in patients with sepsis.     

内毒素休克血浆一氧化氮的变化及其意义

为了探讨一氧比氮与内毒素休克的关系,应用脂多糖建立兔内毒素休克模型,然后应用N-哨基左旋精氨酸治疗,分别观察治疗前后血压,血浆NO的变化.结果发现内毒素休克时,血浆NO浓度升高,静注L-NNA后,休克大白兔血压升高,血浆NO下降.提示内毒素休克时,机体内NO产生增加并与低血压有关,L-NNA可能具有治疗内毒素休克的意义,值得进一步研究.     

The preoptic anterior hypothalamic area mediates initiation of the hypotensive response induced by LPS in male rats

The mechanism responsible for the initiation of endotoxic hypotension is not fully understood, although it is often attributed to a direct effect of LPS and other vasoactive mediators on the vasculature. Alternatively, recent evidence raises the possibility that endotoxic hypotension may be initiated through a central mechanism. Previous studies have shown that LPS initiates fever, sickness behavior, and other aspects of the inflammatory response through a neural pathway that sends peripheral inflammatory signals to the preoptic anterior hypothalamic area (POA). It is also well known that the POA plays a role in the regulation of cardiovascular function, but its involvement in LPS-induced hypotension has not been examined previously. Therefore, the aim of the present paper was to investigate whether the initial abrupt fall in arterial pressure evoked by LPS in septic shock is mediated by the POA. LPS (1 mg/kg, i.v.) administration to halothane-anesthetized or conscious rats lowered arterial blood pressure by 24.8+/-2.9 and 25.1+/-5.8 mmHg, respectively. Bilateral lidocaine (2%; 1 microL) injection into the POA, but not the lateral hypothalamus, prevented the hypotension evoked by LPS entirely in both anesthetized and conscious animals. Remarkably, this blockade significantly inhibited the second, delayed fall in arterial pressure induced by LPS, and simultaneously decreased TNF-alpha plasma levels. Together, these data indicate that the initial phase of endotoxic hypotension is mediated by the POA and suggest that the initiation of the hypotensive response induced by LPS can be essential for the development of the late fall in blood pressure.     

MAP kinase phosphatase 1 controls innate immune responses and suppresses endotoxic shock

Septic shock is a leading cause of morbidity and mortality. However, genetic factors predisposing to septic shock are not fully understood. Excessive production of proinflammatory cytokines, particularly tumor necrosis factor (TNF)-alpha, and the resultant severe hypotension play a central role in the pathophysiological process. Mitogen-activated protein (MAP) kinase cascades are crucial in the biosynthesis of proinflammatory cytokines. MAP kinase phosphatase (MKP)-1 is an archetypal member of the dual specificity protein phosphatase family that dephosphorylates MAP kinase. Thus, we hypothesize that knockout of the Mkp-1 gene results in prolonged MAP kinase activation, augmented cytokine production, and increased susceptibility to endotoxic shock. Here, we show that knockout of Mkp-1 substantially sensitizes mice to endotoxic shock induced by lipopolysaccharide (LPS) challenge. We demonstrate that upon LPS challenge, Mkp-1-/- cells exhibit prolonged p38 and c-Jun NH2-terminal kinase activation as well as enhanced TNF-alpha and interleukin (IL)-6 production compared with wild-type cells. After LPS challenge, Mkp-1 knockout mice produce dramatically more TNF-alpha, IL-6, and IL-10 than do wild-type mice. Consequently, Mkp-1 knockout mice develop severe hypotension and multiple organ failure, and exhibit a remarkable increase in mortality. Our studies demonstrate that MKP-1 is a pivotal feedback control regulator of the innate immune responses and plays a critical role in suppressing endotoxin shock.     

血管活性肠肽对内毒素性休克大鼠肺损伤的保护作用

目的 观察血管活性肠肽(VIP)对内毒索性休克大鼠肺损伤的作用,并探讨其可能机制.方法 SD大鼠静脉注射内毒素(E Coil LPS O111B4)10 mg/kg制作内毒素休克模型.随机将30只大鼠分成对照组(生理盐水,n=10)、内毒素组(内毒素10 mg/kg,n=10)和VIP组(内毒素10mg/kg+VIP 5 nmol,n=10).注药6 h后留取标本,测定各组肺干/湿比(W/D值)、支气管灌洗液(BALF)蛋白浓度和中性粒细胞计数,酶联免疫吸附法(ELISA)测定血清及BALF的肿瘤坏死因子-α(TNF-α)、白介紊-1(IL-1)和IL-10水平,观察肺组织病理变化(光镜+电镜).结果 内毒素组肺W/D值、BALF蛋白浓度和中性粒细胞计数比为(4.75±0.31),(68±6)%,(260±72)mg/L,对照组和VIP组分别为(3.61±0.28),(15±9)%,(70±21)mg/L和(4.02±0.25),(44±8)%,(123±44)mg/L,差异具有统计学意义(P＜0.05).内毒索组血清和BLAF中的TNF-α、IL-1β、IL-10明显升高(P＜0.05),VIP组与内毒素组比较TNF-α、IL-1β明显降低(P＜0.05),但仍高于对照组,IL-10较内毒素组进一步升高.光镜和电镜下VIP组病变轻于内毒素组.结论 VIP可减轻大鼠内毒索休克肺损伤,其作用机制可能与调控炎症细胞因子的表达有关.     

High-density lipoprotein prevents organ damage in endotoxemia

High-density lipoprotein (HDL) may decrease organ injury in sepsis. This study was designed using an animal model to mimic people who had a high HDL level and to test HDL effects on preventing organ damage in endotoxemia. Endotoxemia was induced by an infusion of lipopolysac-charide (LPS) after HDL or LDL administration. Levels of blood biochemical substances, nitrate/nitrite, and TNF-alpha in sera were measured. Pathological examinations were performed 72 hours after LPS infusion. HDL decreased the endotoxin-induced elevation of AST, ALT, BUN, creatinine, LDH, CPK, nitrate/nitrite, and TNF-alpha. On histological examination, neutrophil infiltration was lower in the HDL group. HDL had a significant effect in preventing endotoxin-induced organ damage.     

谷氨酰胺在体内/外对巨噬细胞炎症因子分泌的影响

目的 观察谷氨酰胺(Gln)在体内/外条件下对巨噬细胞炎症反应及热休克蛋白(HSP)表达的影响,探讨Gin在脓毒症时抑制体内炎症反应的机制.方法 实验 1:将培养的腹腔巨噬细胞株RAW264.7分为Gln 0、0.5和8 mmol/L 3组,分别于内毒素脂多糖(LPS)刺激后0、1、4、12和24 h收集细胞及上清液.实验2:45只昆明小鼠被随机均分为假手术(Sham)组、模型组、Gin组;采用盲肠结扎穿孔术(CLP)制备小鼠脓毒症模型,术后即刻从尾静脉注射Gin 0.75 g/kg(Gln组)或等量生理盐水(Sham组和模型组).6 h后采血,腹腔灌洗分离巨噬细胞.用酶联免疫吸附法(ELISA)检测细胞上清液、血清、巨噬细胞裂解液中肿瘤坏死因子-a(TNF-a)、白细胞介素-6(IL-6)、IL-10浓度;用蛋白质免疫印迹法检测巨噬细胞HSP72蛋白表达.结果 体外条件下Gin可显著促进RAW264.7细胞释放TNF-a,IL-6和IL-10,呈剂量和时间依赖性(P＜0.05或P＜0.01),LPS刺激4 h后,Gln 8 mmol/L组RAW264.7细胞HSP72表达显著增加(P均＜0.01).体内条件下,Gin组腹腔巨噬细胞TNF-a、IL-6含量均明显低于模型组(P＜0.01和P＜0.05),3组间IL-10含量比较差异无统计学意义;Gln组血清TNF-a浓度明显低于模型组(P＜0.05),两组血清IL-6、IL-10浓度差异无统计学意义;Gin组巨噬细胞HSP72表达较模型组和Sham组均显著升高(P均＜0.01).结论 Gin体外作用时可显著促进巨噬细胞释放TNF-a和IL-6,且该作用不能被HSP72表达所抑制.体内作用条件下Gln抑制腹腔巨噬细胞合成TNF-a和IL-6.体外和体内条件下Gln都可诱导巨噬细胞表达HSP72,提示HSP72表达可能不是Gln在脓毒症时抑制机体炎症反应的主要机制.     

创伤性休克对大鼠肠淋巴液和血液中内毒素肿瘤坏死因子-α和白细胞介素-6的影响

目的探讨大鼠肠淋巴液在创伤性休克过程中发生细菌移位和炎症反应的可能。方法复制创伤性休克大鼠模型并从肠淋巴干收集淋巴液,比较创伤性休克前后肠淋巴液及血液中内毒素(ET)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)的变化。结果淋巴液中ET、TNF-α、IL-6浓度在休克中明显升高(P均<0.05),复苏后除IL-6持续升高至2h外,ET、TN-α均降至正常水平。结论创伤性休克大鼠休克期可从肠淋巴液观察到细菌移位现象,并可能导致TNF、I-L6水平升高,触发全身炎症反应。     

Age-associated loss of immunomodulatory protection by granulocyte-colony stimulating factor in endotoxic rats

Elderly patients have a higher incidence of morbidity and mortality due to infectious diseases. Because most immune functions in the elderly differ compared with those in younger subjects, we studied the effect of the immunomodulating agent G-CSF on endotoxic liver injury and cytokine release in an aging animal model of acute sepsis. Young (3-month-old), mature (12-month-old), and senescent (24-month-old) male Sprague-Dawley rats (n = 6 each) were treated with bacterial endotoxin for 6 h. Age-matched groups of animals (n = 6 each) received G-CSF (200 microg/kg i.v.) 1 h prior to endotoxin. LPS-induced hepatic toxicity, as assessed in vivo by nutritive perfusion failure, intravascular leukocyte accumulation, biliary excretion dysfunction, and liver enzyme release, was significantly more pronounced in mature and old animals when compared with young animals. Concomitantly, mature but, in particular, senescent endotoxic animals exhibited 2- to 14-fold higher plasma levels of TNF-alpha, IL-1beta, IL-6, IL-10, and Rantes than young endotoxic rats. The percentage of G-CSF receptor surface expression on neutrophils did not significantly differ between young, mature, and senescent animals (36%-46%) and was found comparably down-regulated at 6 h after LPS exposure (15%-19%). Kupffer cell activation, i.e., clearance of intravascularly applied fluorescent latex beads, did not differ between the LPS-exposed age groups. G-CSF dampened LPS-induced Kupffer cell activation, and significantly reduced plasma cytokine levels in young and mature, but not in senescent animals. Thereby, G-CSF caused attenuation of hepatic tissue injury in all except the senescent endotoxic animals. In summary, our results show an age-dependent increase in hepatic LPS toxicity. Because flow cytometric analysis of G-CSF receptor expression disproved that cytokinemia-induced down-regulation of G-CSF receptors might account for the unresponsiveness to G-CSF in the senescent animals, other homeostatic regulatory mechanisms appear to undergo changes with age that bring out a disrupted balance between inflammatory cytokines with unresponsiveness to G-CSF and, thus, compromised host defense mechanisms in the elderly.     

TLR2, TLR4, CD14, CD11B, and CD11C expressions on monocytes surface and cytokine production in patients with sepsis, severe sepsis, and septic shock

ABSTRACT: Bacterial recognition and induced cellular activation are fundamental for the host control of infection, yet the limit between protective and harmful response is still inexact. Forty-one patients were enrolled in this study: 14 with sepsis, 12 with severe sepsis, and 15 with septic shock. Seventeen healthy volunteers (HV) were included as control. The expression of TLR2, TLR4, CD14, CD11b, and CD11c was analyzed on monocytes surface in whole blood. sCD14 was measured in serum, and TNF-alpha, IL-6, and IL-10 cytokine levels were measured in PBMC supernatants after LPS, IL-1beta, and TNF-alpha stimuli by ELISA. An increase in sCD14 and a decreased mCD14 were found in patients as compared with HV (P < 0.001). However, no differences in the expression of TLR2, TLR4, and CD11c were found among the groups. A trend toward differential expression of CD11b was observed, with higher values found in patients with sepsis as compared with HV. A negative regulation of the inflammatory cytokine production was observed in patients with severe sepsis and shock septic in relation to sepsis and HV, regardless of the stimulus. No significant difference in IL-10 production was found among the groups. In this study, we show that the inflammatory response is associated with the continuum of clinical manifestations of sepsis, with a strong inflammatory response in the early phase (sepsis) and a refractory picture in the late phases (severe sepsis and septic shock). Correlation between cell surface receptors and cytokine production after IL-1beta and TNF-alpha stimuli and the observation of a single and same standard response with the different stimulus suggest a pattern of immunology response that is not dependent only on the expression of the evaluated receptors and that is likely to have a regulation in the intracellular signaling pathways.     

Lipopolysaccharide, tumor necrosis factor, and interleukin-1 interact to cause hypotension.

Lipopolysaccharide (LPS) causes the syndrome of septic shock by initiating the release of endogenous mediators such as tumor necrosis factor (TNF) and interleukin-1 (IL-1) from macrophages. Hypotension is one of the important clinical features of septic shock; however, TNF is only hypotensive in high doses. Therefore we have investigated the interactions of low, nonhypotensive doses of LPS, IL-1, and TNF in the restrained unanesthetized rabbit. Combinations of nonhypotensive doses of TNF, IL-1, and LPS produced significant (p less than 0.05) decreases in blood pressure as compared with doses of each of the substances alone. TNF bioactivity in animals that were made hypotensive with combinations of TNF, IL-1, and LPS was lower than in animals that were made hypotensive with TNF alone. This suggests that TNF release that is stimulated by LPS is not the sole cause of the hypotension that is seen in this model of endotoxic shock. In this model, interactions of LPS, IL-1, and TNF occur and may explain hypotension during some episodes of sepsis.