Mortality and bacteriology of sepsis following cecal ligation and puncture in aged mice.

Epidemiologic data suggest that elderly adults are more susceptible to invasive bacterial infection by indigenous gut flora than are younger adults. The purpose of this investigation was to characterize a murine model of clinically encountered peritonitis in the aged. We subjected three different age groups (young, 16 weeks; mature, 12 months; senescent, 24 months) of C57BL/6NNia mice to surgically induced peritonitis by the cecal ligation and puncture procedure. Senescent mice died in a significantly shorter time following surgery than mature mice (median time to death, 24.4 versus 38.5 h, respectively; P less than or equal to 0.001). Blood, liver, spleen and occasionally, ceca were obtained at 2 and 12 h after the cecal ligation and puncture procedure and immediately following death, to characterize the bacterial kinetics of the model. Qualitative and quantitative aerobic, anaerobic, and coliform cultures were performed. No age-related differences were found in the types of bacteria isolated throughout the time course of progressive sepsis. In mice in the mature and senescent age groups, at 2 and 12 h postsurgery, gram-negative anaerobes and gram-positive aerobes predominated in all tissues that were cultured. At the time of death, however, blood and tissue isolates consisted predominantly of coliform bacteria. The shift from mixed infection during sepsis to predominantly gram-negative bacterial infection reflected a similar progressive shift in bacterial types found in the cecum. At death, senescent mice had 100-fold fewer coliform bacteria in the bloodstream than those found in mature mice (2.5 x 10(9) versus 4.6 x 10(11), respectively). The increased sensitivity of aged mice to invasive bacterial infection documented in this series of experiments accords well with human epidemiologic experience and demonstrates the appropriateness of the model for continued investigations of sepsis in the aged.     

LPS pretreatment by the oral route protects against sepsis induced by cecal ligation and puncture. Regulation of proinflammatory response and IgM anti-LPS antibody production as associated mechanisms

Objective: To explore the efficacy of prophylactic oral lipopolysaccharide (LPS) in sepsis induced by cecal ligation and puncture (CLP). Material: Male Balb/c mice. LPS serotype O55: B5 Treatment: Mice were treated every 4 days for a total of 5 times with 50 μg of LPS by intraperitoneal (IP) or oral (O) routes. Treatment was stopped one week prior to CLP. Control (C) groups received the vehicle orally, and sham (S) groups were used as reference. Methods: Histopathology was performed to determine inflammation in liver and lung. Serum cytokines were measured by ELISA, and TNFα tissue expression by RTPCR. Antibodies against LPS were measured by ELISA. Results: Administration of LPS by the oral route significantly increased survival (p<0.05) of mice in association with a reduction of Kupffer cells in liver, pulmonary edema in lung, shorter or delayed TNFα expression in target organs, a trend to decreased IFNγ and increased IL-10 serum levels, and a notable increase in the production of specific IgM anti-LPS antibodies. Conclusions: LPS by oral route protected against CLP. The underlying mechanisms could be the modulation of the proinflammatory response and an increased production of IgM anti-LPS antibodies. Received 12 July 2006; returned for revision 16 November 2006; returned for final revision 14 April 2007; accepted by I. Ahnfelt-R?nne 16 May 2007     

Febrile response induced by cecal ligation and puncture (CLP) in rats: involvement of prostaglandin E<Subscript>2</Subscript> and cytokines

The purpose of the present study was to better understand the events involved in the febrile response induced by cecal ligation and puncture (CLP), a complex infectious process. To this end, we conducted in vivo experiments in rats examining (1) fever development, (2) bacterial number in the infection focus and in blood, (3) peripheral and hypothalamic synthesis of cytokines, (4) hypothalamic and cerebrospinal fluid (CSF) synthesis of prostaglandin E₂ (PGE₂), (5) the effect of anti-IL-6 antibody on fever, and (6) the effect of celecoxib on fever and hypothalamic synthesis of PGE₂ after CLP induction. We found that CLP promotes fever and animal death depending on the number of punctures. The peak of CLP-induced fever overlapped with the maximal increase in the number of bacteria in the infectious focus and blood, which occurred at 6 and 12 h. The peak of the febrile response also coincided with increased amounts of interleukin (IL)-1β, IL-6 and IL-10 in the peritoneal exudate and serum; IL-6 in the hypothalamus and PGE₂ in the CSF and predominantly in the hypothalamus. Moreover, intracerebroventricularly injected anti-IL-6 antibody reduced the febrile response while celecoxib reduced the fever and PGE₂ amount in the hypothalamus induced by CLP. Tumor necrosis factor (TNF)-α peaked at 3 h at all sites studied. Conversely, IL-10 concentration decreased in the hypothalamus. These findings show that the peak of CLP-induced fever is accompanied by an increase of bacteria in peritoneal fluid (local infection) and blood; local synthesis of pyrogenic (IL-1β, IL-6) and antipyretic (IL-10) cytokines and central production of IL-6 and PGE₂, suggesting that these last are the central mediators of this response.     

Early treatment with hydroxyethyl starch 130/0.4 causes greater inhibition of pulmonary capillary leakage and inflammatory response than treatment instituted later in sepsis induced by cecal ligation and puncture in rats

This study investigated the temporal profile of effects of hydroxyethyl starch (HES) 130/0.4 on pulmonary capillary leakage in a rat sepsis model induced by cecal ligation and puncture (CLP). Arterial blood pressure and heart rate were monitored during the experiment. Pulmonary capillary leakage was evaluated at 6, 12, 18, and 24 hr after CLP, and HES 130/0.4 was infused iv 2 hr prior to each time point. Myeloperoxidase (MPO) activity of lung homogenates and pulmonary levels of tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, IL-10, and nuclear factor-kappaB (NF-kappaB) activity were measured. Infusion of HES 130/0.4 attenuated the pulmonary capillary leakage, reduced the elevations of MPO, TNF-alpha, IL-6, and NF-kappaB levels, and further increased the IL-10 level. Infusion of HES 130/0.4 at 4 or 10 hr after the septic insult resulted in the greatest decreases in inflammatory mediators, suggesting that HES 130/0.4 is more protective against pulmonary capillary leakage when given early rather than later during sepsis.     

盲肠结扎穿孔败血症小鼠模型的手术方式优化

目的:探究如何对传统盲肠穿孔结扎(Cecal ligation-and-perforation,CLP)败血症模型手术方式进行优化。方法:选取雄性昆明小鼠103只按是否给予亚胺培南/西司他丁分为:抗生素组、无抗生素组和假手术组。在传统CLP手术方式的基础上缩小手术切口,调整切口位置和术后抗生素用量来观察接受手术小鼠术后存活率及不同批次间小鼠存活率一致性等指标,并与既往文献报道的同类模型进行比较。结果:在本次实验103只小鼠手术中,抗生素组、无抗生素组和假手术组三组小鼠存活时间的分布总体有差异(P=0.026)。组间两两比较发现:抗生素组与无抗生素组7天生存率明显高于无抗生素组(P0.001),假手术组生存率明显高于无抗生素组生存率(P0.001),而抗生素组与假手术组存活率差异无统计学意义(P=0.331)。抗生素组10个批次小鼠存活率的Cronbach’sα系数为0.954。结论:优化后的CLP小鼠模型存活率与传统模型相似,具更亦操作的标准化的手术流程,切口更小,组间生存率一致性高,可重复性好。     

Endogenous hydrogen sulfide regulates leukocyte trafficking in cecal ligation and puncture-induced sepsis

Hydrogen sulfide (H(2)S) is recognized increasingly as a proinflammatory mediator in various inflammatory conditions. Here, we have investigated the role of H(2)S in regulating expression of some endothelial adhesion molecules and recruitment of leukocytes to inflamed sites in sepsis. Male Swiss mice were subjected to cecal ligation and puncture (CLP)-induced sepsis and treated with saline (i.p.), DL-propargylglycine (PAG; 50 mg/kg, i.p.), an inhibitor of H(2)S formation or NaHS (10 mg/kg, i.p.), an H(2)S donor. PAG was administered 1 h before or after the induction of sepsis, and NaHS was given at the same time of CLP. Using intravital microcopy, we found that in sepsis, prophylactic and therapeutic administration of PAG reduced leukocyte rolling and adherence significantly in mesenteric venules coupled with decreased mRNA and protein levels of adhesion molecules (ICAM-1, P-selectin, and E-selectin) in lung and liver. In contrast, injection of NaHS up-regulated leukocyte rolling and attachment significantly, as well as tissue levels of adhesion molecules in sepsis. Conversely, normal mice were given NaHS (10 mg/kg, i.p.) to induce lung inflammation, with or without NF-kappaB inhibitor BAY 11-7082 pretreatment. NaHS treatment enhanced the level of adhesion molecules and neutrophil infiltration in lung. These alterations were reversed by pretreatment with BAY 11-7082. Moreover, expression of CXCR2 in neutrophils obtained from H(2)S-treated mice was up-regulated significantly, leading to an obvious elevation in MIP-2-directed migration of neutrophils. Therefore, H(2)S acts as an important endogenous regulator of leukocyte activation and trafficking during an inflammatory response.     

Lipopolysaccharide-tumor necrosis factor-glucocorticoid interactions during cecal ligation and puncture-induced sepsis in mature versus senescent mice.

Previous work in our laboratory demonstrated increased sensitivity of senescent (24-month-old) mice to cecal ligation and puncture (CLP) sepsis compared with that of mature (12-month-old) mice. In this study the median lethal dose of the strain of Escherichia coli most frequently isolated during CLP sepsis was determined. No significant age-associated difference in the mean lethal dose or the mean survival time was noted; however, sham surgery before injection of E. coli decreased the mean lethal dose by at least 100-fold. With surgical manipulation, the average time to death after bacterial injection simulated more closely that observed after CLP surgery. Host responses to CLP sepsis were investigated by measuring the levels of corticosterone, glucose, and tumor necrosis factor (TNF) in the sera of mature and senescent mice at 2-h intervals after surgery. Corticosterone levels increased gradually during the course of sepsis in mature mice; however, senescent mice demonstrated a pronounced elevation in hormone levels at 2 and 4 h after surgery. At subsequent sampling intervals the corticosterone levels remained elevated, although they were similar for both ages. At all sampling intervals, the glucose levels in serum were lower in senescent mice than in mature mice. Pronounced hypoglycemia (less than 80 mg/dl) was observed in senescent mice at 8 h postsurgery. TNF was detected in serum within a narrow time frame in both age groups at 6, 8, and 10 h postsurgery. Although elevated TNF levels in serum were not seen in every mouse in each group (approximately 50%), the data hinted that senescent animals produced larger quantities of TNF during CLP sepsis than did mature animals. E. coli lipopolysaccharide (1 mg/kg) was injected intraperitoneally, and the TNF levels in serum and peritoneal lavage fluid were measured at 30, 60, and 90 min. Senescent mice demonstrated a level of TNF in serum at 90 min after lipopolysaccharide treatment that was 20-fold higher than that of mature mice (299,877 pg/ml versus 15,594 pg/ml). The amount of TNF produced locally in the peritoneum was also substantially higher in senescent mice than in mature animals (1,716 pg/ml versus 776 pg/ml). The increased production of TNF in senescent animals, despite elevated circulating corticosterone levels, suggested an age-related defect in glucocorticoid-directed downregulation of TNF production. This was confirmed in lipopolysaccharide-treated animals given exogenous dexamethasone.(ABSTRACT TRUNCATED AT 400 WORDS)     

产黑普氏菌内毒素脂多糖的免疫生物学活性研究

目的在体外细胞培养系统和小鼠模型中检测产黑普氏菌ＡＴＣＣ２５８４５内毒素脂多糖对内源性细胞因子的介导活性。方法采用Ｋｒａｍｅｒ测定法、软琼脂细胞培养法和胸腺细胞增殖法测定内毒素脂多糖对肿瘤坏死因子（ｔｕｍｏｒｎｅｃｒｏｓｉｓｆａｃｔｏｒ,ＴＮＦ）、集落刺激因子（ｃｏｌｏｎｙｓｔｉｍｕｌａｔｉｎｇｆａｃｔｏｒ,ＣＳＦ）、白细胞介素１（ｉｎｔｅｒｌｅｕｋｉｎ１,ＩＬ－１）的诱导活性以及局部皮肤斯氏反应（ＳＰＤ５０）。结果产黑普氏菌ＡＴＣＣ２５８４５内毒素可显著地诱导ＴＮＦ、ＣＳＦ和ＩＬ－１的产生,在一定剂量范围内呈剂量依赖型。并可导致家兔典型的皮肤局部斯氏反应。结论产黑普氏菌ＡＴＣＣ２５８４５内毒素脂多糖在动物模型中具有显著的炎症性细胞因子诱导活性     

兔盲肠结扎穿孔早期一氧化氮抗肺动脉压增高和抗氧化作用

目的和方法：采用家兔盲肠结扎穿孔（ＣＬＰ）模型观察了ＣＬＰ前后以及一氧化氮（ＮＯ）合成抑制剂左旋硝基精氨酸（Ｌ－ＮＮＡ）对平均动脉血压（ＭＡＰ），肺动脉压（ＰＡＰ），入、出肺血ＮＯ、丙二醛（ＭＤＡ）含量和超氧化物歧化酶（ＳＯＤ）活性的改变。结果：兔ＣＬＰ后１～５ｈＭＡＰ明显下降，而在２、２５ｈ出现ＰＡＰ明显升高。ＣＬＰ前出肺血ＮＯ含量显著低于入肺血，ＣＬＰ后２５ｈ入肺血ＮＯ含量低于ＣＬＰ前，而出肺血ＮＯ含量与ＣＬＰ前相比无明显差异，且入、出肺血ＮＯ含量无明显差异。ＣＬＰ后２５ｈ入肺血ＭＤＡ含量比ＣＬＰ前有明显增加，出肺血无显著改变；而出肺血ＳＯＤ活性比ＣＬＰ前有明显增高，入肺血无显著改变。注入Ｌ－ＮＮＡ后入、出肺血ＮＯ含量明显降低，各时点ＰＡＰ都明显增高，５ｈ生存率降低，同时入、出肺血ＭＤＡ含量明显升高，ＳＯＤ活性明显下降。结论：肺内ＮＯ含量改变可能与氧自由基有关，在兔ＣＬＰ后早期阶段ＮＯ具抗肺动脉高压和抗氧化的作用     

Mice depleted of CD8+ T and NK cells are resistant to injury caused by cecal ligation and puncture

We previously showed that beta 2 microglobulin knockout mice depleted of NK cells by treatment with anti-asialoGM1 (beta2MKO/alphaAsGM1 mice) are resistant to sepsis caused by cecal ligation and puncture (CLP). beta2MKO mice possess multiple immunological defects including depletion of CD8+ T cells. This study was designed to determine the contribution of CD8+ T and NK cell deficiency to the resistance of beta2MKO/alphaAsGM1 mice to CLP-induced injury. beta2MKO/alphaAsGM1 mice and CD8 knockout mice treated with anti-asialoGM1 (CD8KO/alphaAsGM1 mice) survived significantly longer than wild-type mice following CLP. Improved long-term survival was also observed in wild-type mice rendered CD8+ T/NK cell-deficient by treatment with both anti-CD8alpha and anti-asialoGM1. Blood gas analysis and body temperature measurements showed that CD8+ T and NK cell-deficient mice have significantly reduced metabolic acidosis and less hypothermia compared to control mice at 18 h after CLP. CD8+ T/NK cell-deficient mice also showed an attenuated proinflammatory response as indicated by decreased expression of mRNAs for IL-1, IL-6 and MIP-2 in spleen and heart. IL-6, KC and MIP-2 levels in blood and peritoneal fluid were also significantly decreased CD8+ T/NK cell-deficient mice compared to controls. CD8+ T/NK cell-deficient mice exhibited decreased bacterial concentrations in blood, but not in peritoneal fluid or lung, compared to wild-type controls. These data show that mice depleted of CD8+ T and NK cells exhibit survival benefit, improved physiologic function and an attenuated proinflammatory response following CLP that is comparable to beta2M/alphaAsGM1 mice.     

Role of lipopolysaccharide and cecal ligation and puncture on blood coagulation and inflammation in sensitive and resistant mice models

The hemostatic system is severely disturbed during endotoxemia, leading to a hypercoagulable state. However, it remains uncertain to what extent hypercoagulability is the critical factor in determining the clinical course rather than just the consequence of a severe systemic inflammatory response. To answer this question, we evaluated the evolution of hemostatic and inflammatory markers, as well as histological features, in mice sensitive and resistant to two models of endotoxemia: lipopolysaccharide-injection and cecal ligation puncture. Genetic (knockout mice) and pharmacological (PJ34) blockade of the nuclear enzyme PARP-1 was used to achieve resistance to the endotoxemia. In both models, endotoxemia resulted in antithrombin deficiency, decreased platelets, and fibrin deposition in organs, which were similar in all groups of mice. By contrast, proinflammatory mediators, inflammatory cell infiltration (especially that mediated by mononuclear cells), and organ degeneration were more intense in sensitive animals. Further studies supported a negative role for the triggering of the coagulation cascade in the mortality associated with the endotoxic shock. Hirudin had a minor effect on cell infiltration and organ damage, despite causing a potent inhibition of fibrin deposition. On the other hand, a sublethal dose of lipopolysaccharide yielded significant fibrin deposition but weak activation of the inflammatory response. Our results suggest that activation of coagulation by endotoxemia is severe and independent of the inflammatory response. However, such activation may act with fibrin deposition to have a minor influence on survival in sepsis.     

The effect of sRAGE-Fc fusion protein attenuates inflammation and decreases mortality in a murine cecal ligation and puncture model

Objective

Inhibition of the receptor for advanced glycation end products (RAGE) may attenuate the systemic inflammatory response and ensuing severe sepsis. We report an investigation into the effect of soluble RAGE (sRAGE)-Fc fusion protein in severe sepsis induced by a cecal ligation and puncture (CLP) procedure.

Materials and methods

The experiment was performed using CLP control mice, mice treated with 0.5 or 1.0?μg sRAGE-Fc fusion protein, and sham surgery mice.

Results

Survival benefits over the CLP control group were evident (P?=?0.036) in mice given 1.0?μg sRAGE-Fc fusion protein. In addition, the pulmonary inflammation score in the sRAGE-Fc fusion protein-treated group was significantly lower than that in the CLP control group (P?<?0.05). Lung tissue in the sRAGE-Fc fusion protein-treated group revealed a significant decrease in the expression of inflammatory cytokines. Furthermore, levels of interleukin (IL)-1β and tumor necrosis factor-α were significantly lower in sRAGE-Fc fusion protein treated groups (P?<?0.001). Moreover, IL-6 levels showed a significant difference between CLP control and sRAGE-Fc fusion protein treated groups (P?<?0.01).

Conclusions

sRAGE-Fc fusion protein has beneficial effects in a standard murine model of polymicrobial, intra-abdominal severe sepsis.     

Effect of methylprednisolone on bacterial clearance and endotoxin liberation during experimental sepsis induced by gram-negative bacteria.

To determine the effect of methylprednisolone administration on the clearance of bacteremia and the release and clearance of endotoxin during antibiotic therapy of gram-negative bacterial sepsis, Escherichia coli K1 sepsis was induced in paired rabbits. Moxalactam and either methylprednisolone or placebo were administered to infected rabbits 1.5 h after intraperitoneal administration of live bacteria. Serial blood samples were obtained for quantitation of bacteremia and endotoxemia, arterial blood gases, and complete blood count. Arterial blood pressure, heart rate, and core body temperature were also monitored. There were no significant differences between the methylprednisolone-treated and placebo-treated groups in either the levels of bacteremia or endotoxemia or in the physiologic, metabolic, or hematologic parameters that were measured. We conclude that methylprednisolone administration has no acute effect on bacterial clearance or on the kinetics of endotoxin release and clearance during antibiotic therapy of gram-negative bacterial sepsis in this experimental model.     

Thymulin reverses inflammatory hyperalgesia and modulates the increased concentration of proinflammatory cytokines induced by i.c.v. endotoxin injection

The immunomodulatory thymic hormone thymulin has been shown previously to possess anti-inflammatory actions in the periphery. In this study, we have examined the effect of i.c.v. injections of either endotoxin (ET) or thymulin, in separate groups of conscious rats, on pain-related behavior and cytokine levels in different areas of the brain. Furthermore, we investigated the effect of pretreatment with either i.c.v. or i.p. injections of thymulin on endotoxin-induced hyperalgesia and the effect of pretreatment with i.c.v. thymulin on endotoxin-induced up-regulation of cytokine levels. Our results demonstrate that i.c.v. injection of endotoxin (1 microg in 5 microl saline) resulted in a significant decrease in the nociceptive thresholds as assessed by different pain tests, with peak hyperalgesia at 3 h. However, thymulin at different doses, when injected (i.c.v.), had no significant effect on pain related behavior. Pretreatment (i.c.v.) with thymulin (0.1, 0.5 and 1 microg in 5 microl saline) 20 min before endotoxin (i.c.v.) injection (1 microg in 5 microl saline) reduced, in a dose dependent manner, the endotoxin-induced hyperalgesia and exerted differential effects on the up-regulated levels of cytokines in different areas of the brain. The results provide behavioral and immunochemical characterization of a rat model for intracerebral inflammation and indicates a neuroprotective role for thymulin in the CNS.