Staphylococcus epidermidis induces complement activation, tumor necrosis factor and interleukin-1, a shock-like state and tissue injury in rabbits without endotoxemia. Comparison to Escherichia coli

The antiinflammatory effects of ketamine in endotoxemic rats during moderate and mild hypothermia

Endotoxemia is a common problem among critically-ill patients. We previously found that ketamine inhibited hypotension, metabolic acidosis, and increase of plasma cytokines during endotoxemia in rats. Although endotoxic patients often develop hypothermia, it has not been determined whether ketamine retains its antiinflammatory effects during hypothermia. We investigated the effects of ketamine on endotoxemic rats subjected to moderate and mild hypothermia. Male Wistar rats (n = 100) were anesthetized intraperitoneally with pentobarbital sodium and assigned to one of two protocols: one representing moderate hypothermia (30 degrees C-32 degrees C) and the other, mild hypothermia (33 degrees C-35 degrees C). Each protocol included 5 equal groups: 1). Escherichia coli endotoxin (15 mg/kg IV) in normothermia, 2). ketamine (10 mg x kg(-1) x h(-1) IV) during and after endotoxin injection in normothermia, 3). saline in hypothermia, 4). endotoxin (15 mg/kg IV) in hypothermia, and 5) ketamine (10 mg x kg(-1) x h(-1) IV) in hypothermia after endotoxin injection. Rats were then warmed or cooled to maintain rectal temperatures as above for 6 h. We assessed hemodynamics, acid-base status, and plasma concentrations of tumor necrosis factor-alpha, and interleukin-6. Endotoxemic rats developed hypotension and metabolic acidosis as well as increased plasma cytokine concentrations. At 6 h after endotoxin injection, the mean systolic arterial blood pressure decreased by 71% in the saline/normothermia/endotoxin group, whereas it decreased by only 6%, 41%, and 29% in the ketamine/normothermia/endotoxin, saline/moderate hypothermia/endotoxin, and ketamine/moderate hypothermia/endotoxin groups, respectively. Ketamine administration to endotoxemic rats with hypothermia, whether moderate or mild, also attenuated hypotension, metabolic acidosis, and cytokine increase, but these effects were not superior to those of hypothermia alone. Our findings suggest that, during hypothermia, ketamine administration may not have additive beneficial antiinflammatory effects.

IMPLICATIONS

Although ketamine administration decreased the severity of hypotension and acidosis in endotoxemic rats, ketamine administration may not have additive beneficial antiinflammatory effects during hypothermia.

Delayed dilated cardiomyopathy for major burn injuries

PURPOSE

The early impact on the heart of severe burns has all been well documented previously. Here, we report on the late effects of burns upon the heart, and dilated cardiomyopathy, such aspects having been little reported previously in the literature.

METHODS

Over the past 8 years (June 1991 to December 1998), 55 scalded or flame-burnt patients for whom the total burnt body surface area (TBSA) exceeded 50% were treated. Seventeen patients survived and were followed up. The mean age was 44 years. The mean follow-up period was 47.3 months; four patients displayed a previous history of heart disease. We used several parameters to evaluate and follow cardiac status to see the late effect of burns upon the heart.

RESULTS

Of 17 patients, 3 patients (17.7%) were found to exhibit dilated cardiomyopathies after a mean time of 6 months post-injury. A dramatic recovery from symptoms and roentgenographic findings were observed for all patients following symptomatic treatment.

CONCLUSION

Here we report three cases of delayed dilated cardiomyopathy, a condition that has been little reported in the past. There may be many causating factors. Several recommendations are described.

Gastrointestinal disorders of the critically ill. Shock liver

Shock liver describes a collecting pool of critically ill patients in whom the elevation of liver function tests or overt hepatic dysfunction is apparent. Different grades of shock liver affect about 50% of all intensive-care patients, varying from a mild elevation of serum aminotransferase and bilirubin levels in septic patients to an acute onset of high serum aminotransferases after haemodynamic shock. Abnormalities can subside within days or progressively deteriorate when persistent hepatic microcirculatory failure is present. Although hepatic injury in critically ill patients influences mortality rates it is underdiagnosed. The underlying pathophysiology involves changes in the portal and arterial blood supply as well as in microcirculation. Cross-talk between hepatocytes, Kupffer cells and endothelial cells, leading to an inflammatory response mediated primarily by tumour necrosis factor-alpha (TNF-alpha), is central to shock liver. The liver is a victim of shock inducers, and can also be the orchestrator of the inflammatory response syndrome (IRS). Hepatic injury by TNF-alpha is modulated by the prevalent pro-inflammatory or anti-inflammatory mediator profile elaborated by Kupffer cells. Kupffer cells additionally participate in the clearance of endotoxin, bacteria and inflammatory mediators and are thereby capable of preventing IRS. The hepatocyte undergoes dramatic alterations in synthetic activity, biliary transport, bile flow and glucose metabolism. Although standard determinations of aminotransferases, coagulation studies, glucose, lactate and bilirubin can detect hepatic injury they only partially reflect the cellular mechanisms driving shock liver. The management of shock liver is focused on the prevention of precipitating causes by controlling sepsis, circulation parameters and metabolism in addition to the cautious monitoring of therapeutic measures that can increase hepatic injury, which include intravenous nutrition, mechanical ventilation and catecholamine administration.

Staphylococcus aureus - induced tumor necrosis factor - related apoptosis - inducing ligand expression mediates apoptosis and caspase-8 activation in infected osteoblasts

BACKGROUND

Staphylococcus aureus infection of normal osteoblasts induces expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

RESULTS

Normal osteoblasts were incubated in the presence of purified bacterial products over a range of concentrations. Results demonstrate that purified surface structures and a selected superantigen present in the extracellular environment are not capable of inducing TRAIL expression by osteoblasts. Osteoblasts were co-cultured with S. aureus at various multiplicities of infection utilizing cell culture chamber inserts. Results of those experiments suggest that direct contact between bacteria and osteoblasts is necessary for optimal TRAIL induction. Finally, S. aureus infection of osteoblasts in the presence of anti-TRAIL antibody demonstrates that TRAIL mediates caspase-8 activation and apoptosis of infected cells.

CONCLUSIONS

Collectively, these findings suggest a mechanism whereby S. aureus mediates bone destruction via induction of osteoblast apoptosis.

Induction of cytokine production by different Staphylococcal strains

In light of the important role of cytokines in the pathogenesis of bacterial infections, we analyzed the cytokine production induced by different Staphylococcus aureus (S. aureus), S. epidermidis and S. saprophyticus strains in human mononuclear cells (MNCs). MNCs secreted high amounts of interleukin-1beta (IL-1beta) and IL-6 proteins in responses to stimulation with all three species of Staphylococci. Interestingly, a large majority of the S. aureus strains induced significantly higher IL-12 and interferon (IFN) titers than did the S. epidermidis and S. saprophyticus strains. The RNase protection assay revealed high increases in IL-1alpha, IL-1 beta, IL-1 receptor antagonist, IL-6 and IL-12 p40 transcript levels in MNCs stimulated with Staphylococci. All of the tested Staphylococcal strains proved highly efficient in mediating the induction of these genes. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis indicated considerable increases in IFNA transcript levels in MNCs stimulated with S. aureus strains, while only a very weak expression was stimulated by S. epidermidis and S. saprophyticus. These results confirm that heat-killed Staphylococci exert strong immunomodulatory effects, and suggest that the contribution of T-helper 1 (Th(1)) cells to the immune response may be much extensive in infections caused by S. aureus strains, due to their high IL-12p70 and IFN-alpha-inducing activities.

Evolution of interleukin-1beta

All jawed vertebrates possess a complex immune system, which is capable of anticipatory and innate immune responses. Jawless vertebrates possess an equally complex immune system but with no evidence of an anticipatory immune response. From these findings it has been speculated that the initiation and regulation of the immune system within vertebrates will be equally complex, although very little has been done to look at the evolution of cytokine genes, despite well-known biological activities within vertebrates. In recent years, cytokines, which have been well characterised within mammals, have begun to be cloned and sequenced within non-mammalian vertebrates, with the number of cytokine sequences available from primitive vertebrates growing rapidly. The identification of cytokines, which are mammalian homologues, will give a better insight into where immune system communicators arose and may also reveal molecules, which are unique to certain organisms. Work has focussed on interleukin-1 (IL-1), a major mediator of inflammation which initiates and/or increases a wide variety of non-structural, function associated genes that are characteristically expressed during inflammation. Other than mammalian IL-1beta sequences there are now full cDNA sequences and genomic organisations available from bird, amphibian, bony fish and cartilaginous fish, with many of these genes having been obtained using an homology cloning approach. This review considers how the IL-1beta gene has changed through vertebrate evolution and whether its role and regulation are conserved within selected non-mammalian vertebrates.

Inflammation at the insertion site is not predictive of catheter-related bloodstream infection with short-term, noncuffed central venous catheters

BACKGROUND

Noncuffed, percutaneously inserted central venous catheters (CVCs) are widely used and cause at least 250,000 bloodstream infections (BSIs) in U.S. hospitals each year. We report a prospective study to determine whether inflammation at the insertion site is predictive of CVC-related BSI.

METHODS

Percutaneously inserted, noncuffed CVCs inserted into the subclavian, internal jugular, or femoral vein in two randomized trials during 1998-2000 were prospectively studied; most patients were in an intensive care unit. The condition of the insertion site was evaluated daily by research nurses, quantifying pain (0, 1), erythema (0-2), swelling (0, 1), and purulence (0, 1); the lowest possible overall inflammation score was 0 and the highest was 5. CVC-related BSI was confirmed in each case by demonstrating concordance between isolates from the catheter segment and from blood cultures by restriction-fragment DNA subtyping.

RESULTS

Among 1,263 CVCs prospectively studied, 333 (26.3%) were colonized at removal; of these, 35 catheters (2.7%) caused BSIs (5.9 per 1000 CVC days). BSIs were caused by coagulase-negative staphylococci (n = 27), enterococci (n = 4), enteric Gram-negative bacilli (n = 3), or (n = 1). Most insertion sites showed little or no inflammation at the time of removal. There were no significant differences among mean scores for each inflammatory variable examined or overall score among colonized CVCs (0.1 +/- 0.1), catheters causing CVC-related BSI (0.2 +/- 0.4), and noncolonized CVCs (0.1 +/- 0.1). The sensitivity of local inflammation for diagnosis of CVC-related BSI was dismal (0-3%).

CONCLUSION

Local inflammation is uncommon with infected CVCs, probably because most catheter-associated infections are currently caused by coagulase-negative staphylococci, a pathogen that incites little local or systemic inflammation. Whereas overt inflammation of the insertion site should raise suspicion of CVC-related BSI caused by or Gram-negative bacilli, especially if the patient has fever or other signs of sepsis, in general, site appearance cannot be relied on to identify catheter colonization or CVC-related BSI.

Proinflammatory cytokine IL-1 beta promotes tumor growth of Lewis lung carcinoma by induction of angiogenic factors: in vivo analysis of tumor-stromal interaction

Inflammatory conditions are associated with tumor development. IL-1beta is a multifunctional and proinflammatory cytokine that affects nearly all types of cells. To investigate the role of IL-1beta in tumor growth in vivo, we transduced the retroviral vector coding human IL-1beta gene into mouse Lewis lung carcinoma (LLC) cells and subsequently inoculated the transformant (LLC/IL-1beta) to syngeneic C57BL/6 mice. Tumors derived from LLC/IL-1beta grew faster (240%, day 18, vs null-vector control LLC/neo; p < 0.01) and showed more abundant vasculature (250%, vs LLC/neo; p < 0.05), whereas LLC/IL-1beta cells, LLC/neo cells, and wild-type LLC cells did not show any significant difference in the growth rate in vitro. As compared with LLC/neo cells, LLC/IL-1beta cells secreted 2-fold the amount of vascular endothelial growth factor and >10-fold the amount of macrophage-inflammatory protein-2 (CXCL2), one of whose main functions is angiogenesis. Although LLC/IL-1beta itself did not secrete hepatocyte growth factor (HGF), the tumor derived from LLC/IL-1beta cells also contained a >4-fold higher concentration of HGF, another angiogenic factor. In situ hybridization of HGF mRNA in LLC/IL-1beta tumor sections demonstrated that stromal fibroblasts and infiltrating cells overexpressed HGF mRNA. Moreover, when cultured in the presence of HGF in vitro, LLC/IL-1beta cells secreted even larger amounts of vascular endothelial growth factor and macrophage-inflammatory protein-2. The antiangiogenic agent TNP-470 and anti-CXCR2 Ab inhibited the tumor growth of LLC/IL-1beta cells in vivo. These results indicated that secreting IL-1beta into the tumor milieu induces several angiogenic factors from tumor and stromal cells and thus promotes tumor growth through hyperneovascularization.

Interactions between lipoteichoic acid and peptidoglycan from Staphylococcus aureus: a structural and functional analysis

The cell wall of Gram-positive bacteria contains lipoteichoic acid (LTA) and peptidoglycan (PepG), which synergise to cause shock and organ failure in animals, and to activate human blood to release proinflammatory cytokines. The structural elements within LTA and PepG that are essential for the observed synergism are discussed.

Peptidoglycan from Staphylococcus aureus induces tissue factor expression and procoagulant activity in human monocytes

Staphylococcus aureus is one of the most significant pathogens in human sepsis and endocarditis. S. aureus can initiate blood coagulation, leading to the formation of microthrombi and multiorgan dysfunction in sepsis, whereas in endocarditis the bacterium induces fibrin clots on the inner surface of the heart, so-called endocardial vegetations. In the present study, we show that live and heat-killed S. aureus bacteria are potent inducers of procoagulant activity in human peripheral blood mononuclear cells. Furthermore, purified peptidoglycan, the main cell wall component of S. aureus, induced procoagulant activity in mononuclear cells in a concentration-dependent fashion. The procoagulant activity in these cells was dependent on expression of tissue factor, since antibodies to tissue factor inhibited the effect of peptidoglycan. In mononuclear cells stimulated with peptidoglycan, reverse transcription-PCR showed tissue factor gene expression, and the gene product was detected by enzyme-linked immunosorbent assay. Finally, flow cytometry identified tissue factor at the surface of CD14-positive monocytes. Peptidoglycan is known to induce proinflammatory cytokine production in monocytes. The present investigation shows that peptidoglycan also activates the extrinsic pathway of coagulation by inducing the expression of tissue factor in these cells. This mechanism helps to explain the procoagulant activity, which plays such an important role in the pathogenicity of severe S. aureus infections.

Does endotoxin-activated complement alter myocellular sodium homeostasis during sepsis?

BACKGROUND

Inappropriate complement activation is closely related to tissue injury and organ dysfunction during systemic infection. It is not clear, however, if endotoxin-induced complement activation is responsible for changes in myocellular sodium homeostasis during sepsis.

METHODS

Rats underwent cecal ligation and puncture (CLP) or sham operation. Twenty-four hours after operation, fast-twitch extensor digitorum longus (EDL) muscles were isolated, incubated at 30 degrees C for 1 hour in Krebs-Henseleit buffer (KHB) (pH 7.4), and used to measure intracellular Na+ and K+ contents. Blood samples were collected to measure serum hemolytic complement activity and endotoxin levels. In addition, EDL muscles isolated from normal animals were incubated at 30 degrees C for 1 hour with zymosan-activated (10 mg/mL at 37 degrees C for 1 hour) rat sera, with lipopolysaccharide (LPS)-activated (LPS from Escherichia coli 055:B5, 10 or 200 microg/mL at 37 degrees C for 30 minutes) rat sera, with heat-inactivated (56 degrees C for 30 minutes) rat sera, with LPS (1 or 20 microg/mL), or in KHB. EDL muscles isolated from normal animals were also incubated with septic sera collected 6 or 24 hours after CLP with or without administration of soluble complement receptor type 1 (20 mg/kg, intraperitoneally). Myocellular Na+ and K+ contents ([Na+]i and [K+]i) were assayed using "washout" technique. Soluble C5b-9 complex levels in zymosan-activated or LPS-activated human sera were determined by enzyme-linked immunosorbent assay to evaluate the degree of complement activation induced by zymosan or LPS.

RESULTS

Myocellular [Na+]i and [Na+]i/[K+]i ratios increased significantly 24 hours after CLP as compared with sham operation and were associated with decreased serum hemolytic complement activity and increased serum endotoxin levels. Zymosan-activated rat sera at sublytic concentrations markedly increased [Na+]i and [Na+]i/[K+]i ratios in isolated EDL muscles relative to heat-inactivated rat sera. LPS-activated rat sera, however, did not alter these two indices. In addition, myocellular [Na+]i and [Na+]i/[K+]i ratios were equivalent among normal EDL muscles incubated with septic sera, soluble complement receptor type 1-treated septic sera, or KHB.

CONCLUSION

These results collectively suggest that polymicrobial sepsis, as produced by CLP, alters sodium homeostasis in fast-twitch skeletal muscles in association with changes in systemic complement activation and circulating endotoxin levels. Although endotoxin can activate the complement cascade, endotoxin-induced complement activation does not appear to be responsible for changes in myocellular sodium homeostasis observed during sepsis in rats.

Profound differences in leukocyte-endothelial cell responses to lipopolysaccharide versus lipoteichoic acid

We have investigated the effects of LPS from Escherichia coli, lipoteichoic acid (LTA), and peptidoglycan (PepG) from Staphylococcus aureus, and live S. aureus on leukocyte-endothelial interactions in vivo using intravital microscopy to visualize muscle microvasculature. Systemic vs local administration of LPS induced very different responses. Local administration of LPS into muscle induced significant leukocyte rolling, adhesion, and emigration in postcapillary venules at the site of injection. LPS given systemically dramatically dropped circulating leukocyte counts and increased neutrophils in the lung. However, the drop in circulating leukocytes was not associated with leukocyte sequestration to the site of injection (peritoneum) nor to peripheral microvessels in muscles. Unlike LPS, various preparations of LTA had no systemic and very minor local effect on leukocyte-endothelial interactions, even at high doses and for prolonged duration. LPS, but not LTA, potently activated human endothelium to recruit leukocytes under flow conditions in vitro. Endothelial adhesion molecule expression was also increased extensively with LPS, but not LTA. Interestingly, systemic administration of live S. aureus induced leukocyte-endothelial cell responses similar to LPS. PepG was able to induce leukocyte-endothelial interactions in muscle and peritoneum, but had no effect systemically (no increase in neutrophils in lungs and no decrease in circulating neutrophil counts). These results demonstrate that: 1) LPS has potent, but divergent local and systemic effects on leukocyte-endothelial interactions; 2) S. aureus can induce a systemic response similar to LPS, but this response is unlikely to be due to LTA, but more likely to be mediated in part by PepG.

Effects of posttreatment with propofol on mortality and cytokine responses to endotoxin-induced shock in rats

OBJECTIVE

To clarify the effects of posttreatment with propofol administration on mortality rate and cytokine responses to endotoxin-induced shock in rats.

DESIGN

Randomized prospective laboratory study.

SETTING

University laboratory.

SUBJECTS

Thirty-three male rats.

INTERVENTIONS

Animals were randomly assigned to one of three groups (n = 11 per group): a) endotoxemic group, receiving intravenous Escherichia coli endotoxin (20 mg/kg over 2 mins); b) early posttreatment group, treated identically to the endotoxemic group with the additional administration of propofol (10 mg/kg bolus, followed by infusion at 10 mg x kg(-1) x hr(-1)) 1 hr after the injection of endotoxin; and c) late posttreatment group, treated identically to the endotoxemic group with the additional administration of propofol (10 mg/kg bolus, followed by infusion at 10 mg x kg(-1) x hr(-1)) 2 hrs after the injection of endotoxin.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and arterial blood gases were recorded, and mortality rate and plasma cytokine concentrations were calculated for the 5-hr observation. The mortality rate 5 hrs after endotoxin injection was 73% for the endotoxic, 9% for the early posttreatment, and 36% for the late posttreatment groups. The mortality rate for the early posttreatment group was significantly lower than that for the other groups. The increases in plasma cytokine (tumor necrosis factor-alpha and interleukin-6 and -10) concentrations were less for the early posttreatment group than the other two groups.

CONCLUSIONS

The early posttreatment of propofol after endotoxin injection drastically reduced the mortality rate of rats and attenuated their cytokine responses. Moreover, propofol attenuated the production of tumor necrosis factor-alpha. These findings suggest that propofol administration may be beneficial during sepsis.

Lochial secretions of Escherichia coli- or Arcanobacterium pyogenes-infected bovine uteri modulate the phenotype and the functional capacity of neutrophilic granulocytes

It has been suggested that in cases of puerperal endometritis of cattle infected with Escherichia coli and Arcanobacterium pyogenes, the neutrophils are compromised in their defense capacity or downregulated functionally. In addition to direct bacterial effects, contents of lochial secretions and secreted products of locally activated polymorphonuclear neutrophilic granulocytes (PMNs) may also account for changes in function of freshly immigrating neutrophils. In this study, lochial secretions were obtained from healthy cows and from cows infected by E. coli or A. pyogenes. Separated uterine PMN of infected cows displayed an altered phenotype and function which correlated with the degree of bacterial contamination. Concurrently tested circulating PMN showed no such changes. Infected lochial secretions sterilized by filtration also changed the phenotype of blood PMN. Lochial secretions of healthy cows displayed only minor effects. The effects on PMN function in infected cows varied: ingestion was less affected, whereas generation of reactive oxygen species (ROS) was severely depressed. Concurrently tested purified bacterial products (solubles and fragments) of E. coli and A. pyogenes did not induce the phenotypical and functional changes observed in blood PMN. Since infected lochia also contained high numbers of immigrated and probably activated PMN, the influence of supernatants from phorbol myristate acetate-activated PMN were tested on freshly isolated blood PMN. Such supernatants also increased the expression of certain surface molecules and inhibited the ROS generation. Thus, reduced function and altered phenotypes of PMN which immigrate into the uteri of cows with bacterial endometritis is due not only to interactions with bacteria or bacterial products, but is also to the uterine milieu.

Anti-ovine interleukin-1beta monoclonal antibody immunotherapy in an ovine model of gram-negative septic shock

OBJECTIVE

To investigate the efficacy of an anti-ovine interleukin-1beta monoclonal antibody to ameliorate pathophysiological derangements and improve survival in an ovine model of gram-negative septic shock.

DESIGN

Prospective, placebo-controlled, interventional study (24-hr study period).

SETTING

University hospital animal research laboratory.

SUBJECTS

Ten awake, mature female sheep.

INTERVENTIONS

Seven milligrams per kilogram of intravenous anti-ovine interleukin-1beta immunoglobin G1 monoclonal antibody (anti-interleukin-1beta group, n = 5) or equivalent amount of protein (5% human albumin; control group, n = 5) was infused over 1 hr (time-zero minus 1 hr to time-zero) and followed by an intravenous LD100 live Escherichia coli infusion (time-zero to time-zero plus 1 hr). Normal saline, maintenance and boluses to maintain baseline filling pressures, and gentamicin, 3 mg/kg intravenous, at time-zero plus 2 and time-zero plus 13 hrs.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic and oxygen transport indexes as well as hematological, biochemical, cytokine (interleukin-1beta, tumor necrosis factor-alpha), and endotoxin measurements were performed at baseline (time-zero minus 1 hr), on completion of the monoclonal antibody/placebo (time-zero) and E. coli (time-zero plus 1 hr) infusions, and at multiple time points thereafter (time-zero plus 1.5 hrs to time-zero plus 24 hrs). Baseline data were not different between the treatment groups. From time-zero plus 1.5 hrs onward, in the anti-interleukin-1beta group, there was a sustained increase in mean arterial pressure, decreased peripheral vasodilation, and an attenuated metabolic acidosis, relative to the control group (p < or = .01, repeated-measures analysis of variance). Predicted percentage increases in mean arterial pressure and systemic vascular resistance index relative to the control group were 35% and 40%, respectively. Resuscitation fluid requirements were also decreased: anti-interleukin-1beta group, 4.1 +/- 2.9 mL x kg(-1) x hr(-1); control group, 10.6 +/- 1.8 mL x kg(-1) x hr(-1) (p < or = .01, Student's t-test). Survival was not different (anti-interleukin-1beta group, 40%; control group, 0%; p > .01, log-rank test).

CONCLUSIONS

Adjunctive therapy with anti-ovine interleukin-1beta monoclonal antibody in ovine gram-negative septic shock was associated with improved hemodynamic performance. However, the beneficial effects were incomplete and survival was not significantly improved.

Delayed preconditioning induced by lipoteichoic acid from B. subtilis and S. aureus is not blocked by administration of 5-hydroxydecanoate

Bacterial walls contain lipopolysaccharide (LPS), lipoteichoic acid (LTA), or peptidoglycan. Pretreatment of rats with low doses of LPS (from E. coli) or LTA (from S. aureus, a pathogenic gram-positive bacterium) for 16-24 h reduces myocardial infarct size caused by a subsequent period of myocardial ischemia-reperfusion. This phenomenon of enhanced tolerance to an ischemic insult has been termed delayed preconditioning (DP). The aim of this study was to investigate whether LTA from B. subtilis (a nonpathogenic gram-positive bacterium) induces DP when administered 16 h before left anterior descending coronary artery (LAD) occlusion-reperfusion in the rat. Furthermore, we investigated whether the specific mitochondrial K(ATP) (mitoK(ATP)) channel inhibitor 5-hydroxydecanoate (5-HD, 5 mg/kg) blocks DP afforded by LTA of both strains of bacteria. Male Wistar rats were subjected to LAD occlusion-reperfusion (25-120 min) and infarct size was determined. In rats pretreated with saline (1 mL/kg i.p.), LAD occlusion-reperfusion resulted in an infarct size of 58%. Pretreatment of animals with LTA (S. aureus, 1 mg/kg i.p.) or LTA (B. subtilis, 1 mg/kg i.p.) reduced infarct size by 22% or 33%, respectively. Administration of 5-HD 10 min before LAD occlusion-reperfusion did not abolish DP afforded by LTA from S. aureus or B. subtilis, respectively. These results imply that late (after 16 h) opening of the mitoK(ATP) channel is not part of the signaling pathway of LTA-induced DP.

Significance of elevated serum interleukin-8 in patients resuscitated after cardiopulmonary arrest

The objectives of this study were to analyze changes in serum interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha) levels in patients that restored spontaneous circulation after cardiopulmonary arrest (CPA), and to clarify the cause and significance of elevated serum cytokines after resuscitation. Twenty-eight patients who were admitted to our hospital after out of hospital CPA were studied. Patients' IL-8 levels and TNF-alpha levels in serum increased to a peak within 12 h and within 6 h after the return of spontaneous circulation (ROSC), respectively. Serum IL-8 levels in patients who died or became brain dead within 1 week after ROSC were significantly higher than those in other patients. In stepwise multiple regression analysis, maximum IL-8 values were significantly correlated with maximum TNF-alpha values within post-ROSC 24 h, with the total dose of administered epinephrine and with peripheral neutrophil counts. It is especially noteworthy that the total dose of epinephrine administered during and after resuscitation markedly influenced the elevation of serum IL-8 after ROSC. The increases in serum IL-8 induced by excessive administration of epinephrine might be harmful in the ROSC-patients resuscitated after CPA.

A fulminant hepatic failure model in the rat: involvement of interleukin-1beta and tumor necrosis factor-alpha

The development of a fulminant hepatic failure (FHF) model is necessary for evaluating the efficacy of extracorporeal liver support systems. Recognizing the multifaceted functions of the liver, including synthesis and degradation, we investigated blood chemistry, histological findings, and survival rate in D-galactosamine (GalN)-intoxicated rats. The pathophysiologic response of inflammatory cytokines, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), was also measured. Sprague-Dawley rats (200-300 g) were divided into two groups: GalN and saline injection. Rats were killed at 1, 3, 6, 12, 24, 36, 48, 72, and 168 hr after intraperitoneal injection of GalN (1.4 g/kg) or saline. In both groups, liver-specific markers, liver histology, and IL-1beta and TNF-alpha levels in blood and liver tissue were analyzed. In a second series of experiments, the survival rates were examined after two administrations of GalN at 1.0, 1.4 or 2.0 g/kg, at a 12-hr interval. In the GalN injection group, the liver-specific markers reached peak levels between 36 and 48 hr after injection. Histologically, hepatocellular necrosis was seen at 6-48 hr, followed by a regenerative phase occurring between 72 and 168 hr. IL-1beta and TNF-alpha levels in liver tissue peaked at 12 hr and 1 hr, respectively. The levels of these cytokines in blood, however, did not change significantly. The survival rates at day 7 for 1.0, 1.4 or 2.0 g/kg GalN injected twice were 77.8%, 16.7%, and 0%, respectively. These results suggest that single and double injection of GalN enable the development of reversible and irreversible FHF models. The results also indicate that IL-1beta and TNF-alpha are useful markers of liver injury.

Differential roles of interleukin-18 (IL-18) and IL12 for induction of gamma interferon by staphylococcal cell wall components and superantigens

The roles of endogenous cytokines induced by either intact staphylococcal microorganisms or staphylococcal exotoxins were examined using human whole-blood cultures. To accomplish this, interleukin-18 binding protein (IL-18BP) and tumor necrosis factor binding protein (TNFbp) were used to neutralize IL-18 and TNF, respectively, whereas an anti-IL-12 monoclonal antibody was used to neutralize IL-12 and the IL-1 receptor antagonist (IL-1Ra) was used to block IL-1 receptors. Heat-killed Staphylococcus epidermidis and Staphylococcus aureus, as well as the staphylococcal superantigens toxic shock syndrome toxin-1 (TSST-1) and staphylococcus enterotoxin B (SEB) induced gamma interferon (IFN-gamma) production. Staphylococcus spp.-induced production of IFN-gamma required the presence of endogenous IL-18, IL-12, and TNF. In contrast, TSST-1-induced IFN-gamma was not significantly reduced in the presence of IL-18BP, anti-IL-12 antibodies, IL-1Ra, or anti-TNFbp. SEB-induced IFN-gamma was significantly inhibited only by anti-IL-12 antibodies, indicating that endogenous IL-18, IL-1, and TNF are not required for SEB-induced IFN-gamma. In conclusion, the mechanisms of IFN-gamma stimulation by intact staphylococcal microorganisms and by exotoxins differ, and this is likely due to the different receptors which are triggered on the cell membranes. In contrast to its role in the interactions between staphylococci and host cells, IL-18 does not appear to play a major role in superantigen-induced IFN-gamma.

The selective guanylate cyclase inhibitor ODQ reduces multiple organ injury in rodent models of Gram-positive and Gram-negative shock

OBJECTIVE

An enhanced formation of endogenous nitric oxide contributes to the circulatory failure caused by endotoxin (lipopolysaccharide). Many of the biological actions of nitric oxide are mediated by the guanylate cyclase/cyclic guanosine 3prime;,5'-monophosphate system. We recently discovered that two cell wall components, namely lipoteichoic acid and peptidoglycan of the Gram-positive bacterium Staphylococcus aureus, synergize to cause shock and multiple organ dysfunction syndrome in the rat. Here we investigate the effects of a selective guanylate cyclase inhibitor, 1H-(1,2,4)oxadiazole(4,3-alpha)quinoxaline-1-one (ODQ), on the circulatory failure and multiple organ dysfunction syndrome (kidney, liver, lung) caused by a) coadministration of lipoteichoic acid and peptidoglycan (Gram-positive shock) or b) lipopolysaccharide (Gram-negative shock) in the anesthetized rat. Furthermore, we investigated whether ODQ scavenges superoxide anions and/or hydroxyl radicals.

DESIGN

The in vivo portion of the study was a prospective, randomized, controlled animal study. The in vitro portion included a) cultured ventricular myoblasts of the rat, H9c2(2-1) cells, and b) a cell free superoxide anion assay system.

SETTING

University-based research laboratory.

SUBJECTS

Seventy-five anesthetized, male Wistar rats were used for the in vivo study.

INTERVENTIONS

For the in vivo portion of the study, after surgical preparation, anesthetized rats were observed for 6 hrs. All rats were pretreated and received an intravenous infusion of saline (1.5 mL.kg-1.hr-1), which was maintained throughout the experiment. The rats were assigned to nine groups. Group 1 contained control rats (sham) subjected to 2 mL/kg saline intraperitoneally, 2 hrs before the experiment (n = 7). Group 2 contained control rats (sham) that received 2 mg/kg ODQ intraperitoneally, 2 hrs before the experiment (n = 9). Group 3 contained control rats (sham) that received 2 mL/kg dimethyl sulfoxide, 30% v/v in saline intraperitoneally, as a vehicle for ODQ, 2 hrs before the experiment (n = 6). In group 4 rats, Gram-positive shock was induced by coadministration of lipoteichoic acid (3 mg/kg intravenously) and peptidoglycan (10 mg/kg intravenously) (n = 10). In group 5, rats were pretreated with ODQ (as described previously) before lipoteichoic acid/peptidoglycan (n = 9). In group 6, rats were pretreated with dimethyl sulfoxide (as described previously) before lipoteichoic acid/peptidoglycan (n = 7). In group 7, Gram-negative shock was induced by lipopolysaccharide (6 mg/kg intravenously) (n = 11). In group 8, rats were pretreated with ODQ (as described previously) before lipopolysaccharide (n = 8). In group 9, rats were pretreated with dimethyl sulfoxide (as described previously) before lipopolysaccharide (n = 8). For the in vitro portion of the study, rat cells were preincubated with vehicle (saline and/or dimethyl sulfoxide) and ODQ (0.1 microM to 1 mM) for 2 hrs. The cells then were exposed to H2O2 (1 mM) for 4 hrs at 37 degrees C, after which time cell viability was determined by measuring the mitochondrial-dependent reduction of 3-(4,5-di-methyliazol-2-yl)-2,5-diphenyltetrazolium bromide to blue formazan. Next, an aqueous solution was incubated with ODQ (as described previously), and superoxide anions were produced by using a hypoxanthine/xanthine-oxidase assay. The chemiluminescence assay was used to evaluate any potential antioxidative effects of ODQ.

MEASUREMENTS AND MAIN RESULTS

In vivo, administration of lipoteichoic acid/peptidoglycan or lipopolysaccharide resulted within 6 hrs in hypotension, acute renal dysfunction, hepatocellular injury, and lung injury. Pretreatment of rats with ODQ attenuated the renal dysfunction, lung injury, and hepatocellular injury caused by lipoteichoic acid/peptidoglycan or lipopolysaccharide. In vitro, administration of H2O2 (for 4 hrs) to rat cardiomyoblasts decreased mitochondrial respiration attributable to generation of hydroxyl radicals. Pretreatment of cells with ODQ did not abolish this cell injury. In addition, ODQ did not scavenge superoxide anions.

CONCLUSIONS

These results imply that ODQ, an inhibitor of guanylate cyclase, reduces the multiple organ injury and dysfunction caused by wall fragments of Gram-positive or Gram-negative bacteria in the anesthetized rat. The observed protective effects of ODQ are not attributable to the ability of ODQ to reduce the formation or the effects of superoxide anions or hydroxyl radicals.

A fulminant hepatic failure model in the rat: involvement of interleukin-1beta and tumor necrosis factor-alpha

The development of a fulminant hepatic failure (FHF) model is necessary for evaluating the efficacy of extracorporeal liver support systems. Recognizing the multifaceted functions of the liver, including synthesis and degradation, we investigated blood chemistry, histological findings, and survival rate in D-galactosamine (GalN)-intoxicated rats. The pathophysiologic response of inflammatory cytokines, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), was also measured. Sprague-Dawley rats (200-300 g) were divided into two groups: GalN and saline injection. Rats were killed at 1, 3, 6, 12, 24, 36, 48, 72, and 168 hr after intraperitoneal injection of GalN (1.4 g/kg) or saline. In both groups, liver-specific markers, liver histology, and IL-1beta and TNF-alpha levels in blood and liver tissue were analyzed. In a second series of experiments, the survival rates were examined after two administrations of GalN at 1.0, 1.4 or 2.0 g/kg, at a 12-hr interval. In the GalN injection group, the liver-specific markers reached peak levels between 36 and 48 hr after injection. Histologically, hepatocellular necrosis was seen at 6-48 hr, followed by a regenerative phase occurring between 72 and 168 hr. IL-1beta and TNF-alpha levels in liver tissue peaked at 12 hr and 1 hr, respectively. The levels of these cytokines in blood, however, did not change significantly. The survival rates at day 7 for 1.0, 1.4 or 2.0 g/kg GalN injected twice were 77.8%, 16.7%, and 0%, respectively. These results suggest that single and double injection of GalN enable the development of reversible and irreversible FHF models. The results also indicate that IL-1beta and TNF-alpha are useful markers of liver injury.

Isolation and characterization of a highly specific serine endopeptidase from an oral strain of Staphylococcus epidermidis

Infection by Staphylococcus epidermidis, an opportunistic pathogen, has become a major problem due to the increased use of implanted medical devices and the growing number of patients who are therapeutically or infectiously immunosuppressed. These infections appear to proceed via modulation of the coagulation and complement systems. In this communication we describe the purification and characterization of a novel extracellular proteinase from an oral strain of S. epidermidis that can degrade fibrinogen, complement protein C5, and several other proteins. This proteinase has a strong preference for cleavage after glutamic acid residues, but not after aspartic acid. The S. epidermidis enzyme may be a multifunctional protein which not only provides this organism with both the ability to evade the complement defense system and to dysregulate the coagulation cascade, but also supplies nutrients for its growth through the degradation of Glu-rich proteins.

Hepatic response to sepsis: interaction between coagulation and inflammatory processes

OBJECTIVES

a) To review the hepatic response to sepsis and to establish how this response contributes to coagulation and inflammatory processes; b) to review the physiologic and biochemical mechanisms that suggest hepatic dysfunction may occur during sepsis, enhance procoagulant and proinflammatory activities, and participate in the potential evolution to multiple organ dysfunction syndrome.

DATA SOURCES

A summary of published medical literature from MEDLINE search files and published reviews on liver function in experimental and human sepsis.

DATA SUMMARY

In sepsis, the liver plays a major role in host defense mechanisms. Kupffer cells are responsible for bacterial scavenging, bacterial products inactivation, and inflammatory mediators clearance and production. Hepatocytes, via receptors for many proinflammatory cytokines, modify their metabolic pathway toward gluconeogenesis, amino-acid uptake, and increased synthesis of coagulant and complement factors and protease inhibitors. The acute-phase protein (APP) response also contributes to the procoagulant state, especially by enhancing the inhibition of protein C (alpha1-antitrypsin and alpha2-macroglobulin) and by decreasing liver synthesis of protein C and antithrombin (negative APPs). Elevated C-reactive protein levels (positive APPs) promote the expression of tissue factor by mononuclear cells. Increased liver production of thrombin-activatable fibrinolytic inhibitor (positive APPs) enhances fibrinolysis inhibition. Conversely, such hepatic inflammatory and coagulation processes in sepsis may alter the function of this organ. Indeed, the liver can be injured by activated Kupffer cells that release chemokines, attract blood neutrophils into the liver, and activate them. Neutrophils up-regulate their surface adhesion molecules, tissue factor, and Kupffer cells, whereas tissue factor pathway inhibitor and thrombomodulin are almost undetectable in endothelial cells. This may lead to microcirculatory disturbances, fibrin deposition, hepatocyte injury, endotoxin and bacteria spillover, and multiple organ failure.

CONCLUSIONS

In sepsis, the liver participates in host defense and tissue repair through hepatic cell cross-talk that controls most of the coagulation and inflammatory processes. When this control is not adequate, a secondary hepatic dysfunction may occur and may sometimes lead to bacterial products spillover, enhanced procoagulant and inflammatory processes, and in turn, multiple organ failure and death.

Recombinant lipoproteins: lipoprotein-like lipid particles for drug targeting

Lipoproteins are endogenous particles that transport lipids through the blood to various cell types, where they are recognised and taken up via specific receptors. These particles are, therefore, excellent candidates for the targeted delivery of drugs to various tissues. For example, the remnant receptor and the asialoglycoprotein receptor (ASGPr), which are uniquely localised on hepatocytes, recognise chylomicrons and lactosylated high density lipopoteins (HDL), respectively. In addition, tumour cells of various origins overexpress the low density lipoprotein (LDL) receptor that recognises apolipoprotein E (apoE) on small triglyceride-rich particles and apoB-100 on LDL. Being endogenous, lipoproteins are biodegradable, do not trigger immune reactions, and are not recognised by the reticuloendothelial system (RES). However, their endogenous nature also hampers large-scale pharmaceutical application. In the past two decades, various research groups have successfully synthesised recombinant lipoproteins from commercially available natural and synthetic lipids and serum-derived or recombinant apolipoproteins, which closely mimic the metabolic behaviour of their native counterparts in animal models as well as humans. In this paper, we will summarise the studies that led to the development of these recombinant lipoproteins, and we will address the possibility of using these lipidic particles to selectively deliver a wide range of lipophilic, amphiphilic, and polyanionic compounds to hepatocytes and tumour cells. In addition, the intrinsic therapeutic activities of recombinant chylomicrons and HDL in sepsis and atherosclerosis will be discussed.

Commercial preparations of lipoteichoic acid contain endotoxin that contributes to activation of mouse macrophages in vitro

Lipoteichoic acids (LTA), cell wall components of gram-positive bacteria, have been reported to induce various inflammatory mediators and to play a key role in gram-positive-microbe-mediated septic shock. In a large number of these studies, investigators used commercially available LTA purified from a variety of gram-positive bacteria, including Staphylococcus aureus, Bacillus subtilis, and Streptococcus sanguis. We report here that, although these commercially available LTA could be readily shown to stimulate production of nitric oxide (NO) in RAW 264.7 mouse macrophages, the activity was dramatically inhibited by polymyxin B, a relatively specific inhibitor of endotoxin biological activity. One-step purification of the commercially available S. aureus LTA using hydrophobic interaction chromatography resulted in two well-separated peak fractions, one highly enriched for LTA and a second highly enriched for endotoxin. The LTA-enriched fractions did not induce production of NO in RAW 264.7 macrophages, although they caused a dose-dependent induction of NO in the presence of low concentrations of gamma interferon (IFN-gamma) (which by itself induced little NO), regardless of the presence of polymyxin B. In contrast, the endotoxin-enriched fractions by themselves inhibited in high levels of NO in RAW 264.7 macrophages but activity was almost completely inhibited in the presence of polymyxin B. Consistent with these findings, our data also indicate that commercial LTA preparations from S. aureus, B. subtilis, and S. sanguis were not able to induce NO from lipopolysaccharide-hyporesponsive C3H/HeJ mouse peritoneal macrophages, but in the presence of IFN-gamma, these LTA preparations were able to induce relatively high levels of NO from C3H/HeJ macrophages. These results indicate that commercially available LTA can contain contaminating and potentially significant levels of endotoxin that can be expected to contribute to the putative macrophage-stimulating effects of LTA as assessed by NO production. The fact that the purified LTA, by itself, was not able to induce significant levels of NO secretion in RAW 264.7 macrophages supports the conclusion that caution in attributing high-level biological activity to this microbial cell wall constituent should be exercised.

Influence of interferon-gamma administration on the severity of experimental group B streptococcal arthritis

OBJECTIVE

To assess the effect of interferon-gamma (IFNgamma) administration on the evolution of systemic infection and septic arthritis induced by group B streptococci (GBS) in mice.

METHODS

CD1 mice were inoculated intravenously with arthritogenic strain 1/82 of type IV GBS. Exogenous murine IFNgamma or anti-IFNgamma monoclonal antibodies were administered intravenously either 2 hours (-2 hours) before or 18 hours after infection with 1 x 10(7) GBS. Mice were monitored daily for survival and for signs of arthritis. In a subsequent set of experiments, mice were killed at selected times for examination of bacterial clearance, joint histopathology, and cytokine production.

RESULTS

Mortality in mice treated with IFNgamma at -2 hours was 100%, compared with 20% in those treated at 18 hours and with 40% in controls. As indicated by the arthritis score, mice treated with IFNgamma at -2 hours developed early and more severe arthritis, whereas those treated at 18 hours had milder arthritis compared with infected controls. Less severe joint pathology in the mice treated with IFNgamma at 18 hours correlated with low levels of interleukin-6 (IL-6) and IL-1beta and a low bacterial load in the joints, whereas rapid onset and worsening of articular lesions in those treated at -2 hours corresponded to early and sustained levels of IL-6.

CONCLUSION

The findings of this study demonstrate that the effects mediated by IFNgamma on GBS-induced arthritis may be detrimental or beneficial, depending on the time of administration of IFNgamma in relation to infection with the antigen.

Microspheres containing neutralizing antibodies to tumor necrosis factor-alpha and interleukin-1 beta protect rats from Staphylococcus aureus-induced peritonitis

Previous studies using microencapsulated neutralizing antibodies (NA) to tumor necrosis factor (TNF) and interleukin-1 (IL-1) in combination with gentamicin have demonstrated improved survival in a peritonitis model of gram-negative septic shock. Microencapsulation has been shown to improve the effectiveness of NA by delivering them intracellularly, taking advantage of the natural phagocytic activity of the macrophage. It is the purpose of this study to see if microencapsulated NA to TNF and IL-1 in combination with vancomycin can improve survival compared with NA in solution in Staphlococcus aureus-induced septic shock. Groups of 10 rats received the following treatments: (1) S. aureus plus no treatment, (2) S. aureus plus blank microspheres, (3) S. aureus plus vancomycin, (4) S. aureus plus a microsphere form of NA and vancomycin, (5) S. aureus plus a solution form of NA and vancomycin, (6) S. aureus plus a microsphere form of NA, and (7) S. aureus plus a solution form of NA. Survival was monitored for 5 days, and plasma TNF and IL-1 levels were measured for 48 h after S. aureus administration. All (100%) animals that received the microsphere form of NA plus vancomycin, 20%-70% of the animals that received the microsphere form of NA alone, and 20% of the animals that received antibiotics alone survived for 5 days or more. None of the animals in the no treatment group or blank microsphere treatment group and only 10% of the animals in the solution form of NA plus or minus vancomycin group survived for more than 5 days. Plasma TNF and IL-1 levels were significantly increased after S. aureus treatment. Simultaneous and delayed treatment with the microsphere form of NA plus or minus vancomycin significantly reduced TNF and IL-1 levels, and the solution form of NA significantly reduced only TNF levels after immediate treatment. The survival rate was higher in animals with lower TNF levels and IL-1 levels. The results demonstrate that the microsphere form of cytokine NA is 100% effective in combination with vancomycin in protecting rats from S. aureus-induced peritonitis. The microsphere form was also more efficient in attenuating both TNF and IL-1 levels.

Differential tumor necrosis factor alpha expression and release from peritoneal mouse macrophages in vitro in response to proliferating gram-positive versus gram-negative bacteria

Viable Escherichia coli and Staphylococcus aureus bacteria elicited markedly different in vitro tumor necrosis factor alpha (TNF-alpha) responses when placed in coculture with peritoneal murine macrophages. These include quantitative differences in TNF-alpha mRNA expression and corresponding protein product secretion as well as kinetic differences in the profiles of the TNF-alpha responses. Further, lipopolysaccharide (from E. coli) is a major contributing factor to these differences, as revealed by comparative experiments with endotoxin-responsive (C3Heb/FeJ) and endotoxin-hyporesponsive (C3H/HeJ) macrophages. Nevertheless, the eventual overall magnitude of the TNF-alpha secretion of macrophages in response to S. aureus was at least equivalent to that observed with E. coli, while appearing at time periods hours later than the E. coli-elicited TNF-alpha response. Both the magnitude and kinetic profile of the TNF-alpha responses were found to be relatively independent of the rate of bacterial proliferation, at least to the extent that similar results were observed with both viable and paraformaldehyde-killed microbes. Nevertheless, S. aureus treated in culture with the carbapenem antibiotic imipenem manifests markedly altered profiles of TNF-alpha response, with the appearance of an early TNF-alpha peak not seen with viable organisms, a finding strikingly similar to that recently reported by our laboratory from in vivo studies (R. Silverstein, J. G. Wood, Q. Xue, M. Norimatsu, D. L. Horn, and D. C. Morrison, Infect. Immun. 68:2301-2308, 2000). In contrast, imipenem treatment of E. coli-cocultured macrophages does not significantly alter the observed TNF-alpha response either in vitro or in vivo. In conclusion, our data support the concept that the host inflammatory response of cultured mouse macrophages in response to viable gram-positive versus gram-negative microbes exhibits distinctive characteristics and that these distinctions are, under some conditions, altered on subsequent bacterial killing, depending on the mode of killing. Of potential importance, these distinctive in vitro TNF-alpha profiles faithfully reflect circulating levels of TNF-alpha in infected mice. These results suggest that coculture of peritoneal macrophages with viable versus antibiotic-killed bacteria and subsequent assessment of cytokine response (TNF-alpha) may be of value in clarifying, and ultimately controlling, related host inflammatory responses in septic patients.

The prophylactic effects of natural water-soluble antioxidant from spinach and apocynin in a rabbit model of lipopolysaccharide-induced endotoxemia

Radical-scavenging antioxidants, as part of the cellular defense system, function to inhibit the formation and propagation of free radicals and active oxygen species formation. In previous studies we demonstrated that endotoxin lipopolysaccharide (LPS) promotes oxidative stress and associated pathological changes in a rat model and that use of selected antioxidants was effective in reducing LPS-related lipid peroxidation product formation in the liver, as well as LPS-related pathological changes in different organs. In this study, several toxicological parameters (ie, clinical signs, blood chemistry, and histopathological changes) were compared among groups of male New Zealand rabbits injected with LPS following prophylactic pretreatment with either of 2 antioxidants, a group injected with LPS without pretreatment with antioxidants, groups injected with either of the 2 antioxidants only, and an untreated control group. The antioxidants used were a water-soluble natural antioxidant (NAO) from spinach and the NADPH oxidase inhibitor, apocynin. Exposure to LPS alone was associated clinically with depression, tachypnea, outer ear vasodilation, and iris congestion; biochemically with a significant increase in blood total bilirubin, transaminase activity, and glucose, total cholesterol, and triglyceride levels; macroscopically with multiple whitish areas in the liver; and histologically with hepatocellular focal necrosis and acute inflammation, thymic and splenic lymphoid necrosis and depletion, acute uveitis and hemorrhages in the ciliary processes, and decreased adrenal cortical cytoplasmic vacuolation considered consistent with depletion of steroidal hormone contents. The NAO had more effective prophylactic capacities than the apocynin. The protective effects were obvious in all investigated parameters. The results indicate the possible therapeutic efficacy of NAO in the treatment of clinical endotoxemia associated with gram-negative bacterial sepsis that is known to be associated with oxidative stress.

Membrane-permeable radical scavenger, tempol, reduces multiple organ injury in a rodent model of gram-positive shock

OBJECTIVE

An enhanced formation of reactive oxygen species contributes to the multiple organ dysfunction syndrome (MODS) caused by endotoxin. We have recently discovered that two cell wall components, namely lipoteichoic acid (LTA) and peptidoglycan (PepG) of the gram-positive bacterium, Staphylococcus aureus, synergize to cause shock and MODS in the rat. Here, we investigate the effects of a membrane-permeable radical scavenger (tempol) on the circulatory failure and MODS (kidney, liver, lung) caused by coadministration of LTA (3 mg/kg i.v.) and PepG (10 mg/kg i.v.) in the anesthetized rat.

DESIGN

Prospective, randomized study.

SETTING

University-based research laboratory.

SUBJECTS

Thirty-four anesthetized, male Wistar rats.

INTERVENTIONS

After surgical preparation, anesthetized rats were observed for 6 hrs. Control rats were given vehicle (control plus saline, 2 mL/kg bolus injection, followed by an infusion of 1.5 mL/kg i.v., n = 6) or tempol (control plus tempol, 100 mg/kg i.v. bolus injection, followed by an infusion of 30 mg/kg i.v., n = 6). Gram-positive septic shock was induced by coadministration of LTA (3 mg/kg i.v.) and PepG (10 mg/kg i.v.) (LTA/PepG plus saline, n = 12). Another group of rats was pretreated with tempol before shock was induced (LTA/PepG plus tempol, 100 mg/kg i.v. bolus injection, 15 mins before LTA/PepG administration, followed by an infusion of 30 mg/kg i.v., n = 10).

MEASUREMENTS AND MAIN RESULTS

Within 6 hrs, administration of LTA/PepG resulted in hypotension, acute renal dysfunction, hepatocellular injury, pancreatic injury, and increased plasma concentrations of nitrite/nitrate. Pretreatment of rats with tempol augmented the hypotension but attenuated the renal dysfunction and the hepatocellular injury/dysfunction caused by LTA/PepG. Tempol did not affect the increase in nitrite/nitrate caused by LTA/PepG.

CONCLUSIONS

These results imply that an enhanced formation of reactive oxygen species (including superoxide anions) contributes to the kidney and liver injury and dysfunction caused by LTA/PepG in the anesthetized rat.

Lipoteichoic acid induces delayed protection in the rat heart: A comparison with endotoxin

Classic ischemic preconditioning transiently (30 to 120 minutes) protects the myocardium against subsequent lethal ischemia/reperfusion injury. After dissipation of this acute protection, a second window of protection (SWOP) appears 12 to 24 hours later; this SWOP lasts up to 3 days. Several triggers induce a SWOP, including brief repetitive cycles of coronary artery occlusion, rapid ventricular pacing, stimulation of adenosine A(1) receptors, and administration of wall fragments of Gram-negative bacteria, such as lipopolysaccharide (LPS). The aim of this study was to investigate whether lipoteichoic acid (LTA), a cell wall fragment of Gram-positive bacteria, can induce a SWOP in a rat model of left anterior descending coronary artery (LAD) occlusion (25 minutes) and reperfusion (2 hours). Thus, 166 male Wistar rats were pretreated (2 to 24 hours) with saline, LTA (1 mg/kg IP), or LPS (1 mg/kg IP) and subjected to LAD occlusion/reperfusion. Pretreatment with LTA or LPS for 16 hours led to a substantial, approximately 65%, reduction in infarct size and a reduction in the release of cardiac troponin T into the plasma. The dose of LTA used had no toxic effect (on any of the parameters studied), whereas the same dose of LPS caused a time-dependent activation of the coagulation system and liver injury. By use of RNase protection assays, it was determined that LPS caused a time-dependent induction of tumor necrosis factor-alpha, interleukin-1beta, and manganese superoxide dismutase mRNA content in the heart, whereas LTA failed to induce manganese superoxide dismutase. LPS also caused an upregulation of the expression of intercellular adhesion molecule-1 and P-selectin, whereas LTA downregulated these molecules and attenuated the accumulation of polymorphonuclear granulocytes caused by myocardial ischemia/reperfusion. This study demonstrates for the first time that pretreatment with LTA at 8 to 24 hours before myocardial ischemia significantly reduces (1) infarct size, (2) cardiac troponin T, and (3) the histological signs of tissue injury in rats subjected to LAD occlusion and reperfusion. The mechanism(s) underlying the observed cardioprotective effects of LTA warrants further investigation but is likely to be related to its ability to inhibit the interactions between the coronary vascular endothelium and polymorphonuclear granulocytes. Therefore, LTA represents a novel and promising agent capable of enhancing myocardial tolerance to ischemia/reperfusion injury.

Depression of constitutive murine cytochromes P450 by staphylococcal enterotoxin B

Most in vivo studies demonstrating decreased activities of hepatic cytochromes P450 with inflammation have used Gram-negative bacterial lipopolysaccharide (LPS) as the inflammatory stimulant. But products of Gram-positive bacteria, such as staphylococcal enterotoxin B (SEB), also stimulate inflammatory mediators, albeit with a different pattern than LPS. Therefore, effects of SEB on the regulation of murine constitutive P450s were determined in this study and compared with those of LPS. LPS-responsive C3H/HeN and LPS-unresponsive C3H/HeJ mice were injected with either LPS (0.5 mg/kg) or SEB (0.66 to 6.6 mg/kg), and hepatic cytochromes P450 and serum tumor necrosis factor-alpha, interleukin-6, nitrate/nitrite, and serum amyloid A concentrations were determined up to 24 hr. HeJ mice were generally less responsive than HeN mice to both stimuli, with lower cytokine, nitrate/nitrite, and serum amyloid A responses. However, in both mouse strains SEB caused more prolonged cytokine, higher nitrate/nitrite, and lower serum amyloid A concentrations than LPS. Despite these differences, in HeN mice, after both SEB and LPS administration, total P450 concentrations were equally depressed by 40%. Both SEB and LPS depressed CYP1A1 and 1A2 microsomal protein concentrations by 45 and 30%, respectively; CYP2E1 by 64%; and CYP3A by 70%. There was comparable inhibition of enzymatic activities. In HeJ mice, SEB was only slightly more effective in depressing P450s than LPS, as might be expected. These data showed that the Gram-positive bacterial inflammatory stimulant SEB caused effects on murine hepatic cytochromes P450 similar to those of LPS, even though the pattern of inflammatory mediators induced after SEB exposure was different.

Myocardial dysfunction in septic shock

Over the last decade, it has become clear that myocardial depression, like vascular dysfunction, is typical of human septic shock. Human septic myocardial depression is characterized by reversible biventricular dilatation, decreased ejection fraction, and decreased response to fluid resuscitation and catecholamine stimulation (in the presence of overall hyperdynamic circulation). A circulating myocardial depressant substance, not myocardial hypoperfusion, is responsible for this phenomenon. This substance has been shown to represent low concentrations of TNF-alpha and IL-1 beta acting in synergy on the myocardium through mechanisms that include NO and cGMP generation. Despite major advances in our understanding of the hemodynamics and pathogenesis of cardiac dysfunction in sepsis, successful attempts to modulate these mechanisms to improve clinical outcomes in human trials have not been demonstrated to date. For the moment, the therapeutic approach to the patient with cardiac dysfunction in distributive or septic shock must be primarily aimed at reestablishing adequate organ perfusion and oxygen delivery by vigorous fluid resuscitation and vasopressor or inotropic support. In the long term, however, only continued research regarding the cellular mechanisms of organ dysfunction, including septic myocardial depression, will lead to successful therapeutic strategies. These strategies will likely involve direct manipulation of intracellular signaling processes that lead to organ dysfunction as manifested by septic myocardial dysfunction and septic shock.

Effects of propofol on hemodynamic and inflammatory responses to endotoxemia in rats

OBJECTIVE

To document the effects of propofol on the hemodynamic and inflammatory responses to endotoxemia in an animal model.

DESIGN

Randomized, prospective laboratory study.

SETTING

University experimental laboratory.

SUBJECTS

Thirty-two male rats.

INTERVENTIONS

The animals were randomly assigned to one of four groups: a) endotoxemia group (n = 8), which received intravenous Escherichia coli endotoxin (15 mg/kg over 2 mins); b) control group (n = 8), which was treated identically to the endotoxemia group except for the substitution of 0.9% saline for endotoxin; c) propofol group (n = 8), which was treated identically to the control group but also received propofol (10 mg/kg bolus, followed by infusion at 10 mg/kg/hr) immediately after the injection of 0.9% saline; and d) propofol-endotoxemia group (n = 8), which was treated identically to the endotoxemia group with the additional administration of propofol (10 mg/kg bolus, followed by infusion at 10 mg/kg/hr) immediately after endotoxin injection.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics, arterial blood gases, and acid-base status were recorded and the blood propofol concentrations and plasma cytokine concentrations were measured during the 5-hr observation. Microscopic findings of lung tissue for each group were obtained at necropsy. The systolic arterial pressure and heart rate of the propofol-endotoxemia group were similar to those of the endotoxemia group. The increases in the plasma cytokine (tumor necrosis factor, interleukin-6, and interleukin-10) concentrations, in the base deficit, and in the infiltration of neutrophils in the air space or vessel walls of the lungs were attenuated in the propofol-endotoxemia group compared with the endotoxemia group.

CONCLUSIONS

Propofol attenuated cytokine responses, base deficit, and activation of neutrophils to endotoxemia. These findings suggest that propofol may inhibit inflammatory response and prevent the development of metabolic acidosis during endotoxemia.

Effects of lidocaine administration on hemodynamics and cytokine responses to endotoxemia in rabbits

OBJECTIVE

To investigate the effects of lidocaine administration on hemodynamics and cytokine concentrations in Escherichia coli endotoxemia in rabbits.

DESIGN

Randomized, prospective laboratory study.

SETTING

University laboratory.

SUBJECTS

Thirty-two Japanese rabbits anesthetized with urethane and ventilated mechanically.

INTERVENTIONS

Animals were randomly assigned to one of four groups: endotoxemic controls (n = 8), receiving intravenous E. coli endotoxin (0.5 mg/kg bolus) via the mesenteric vein; laparotomy controls (n = 8), treated identically to the endotoxemic controls except for the substitution of 0.9% saline for endotoxin; lidocaine controls (n = 8), treated identically to the laparotomy controls with the addition of intravenous lidocaine (3 mg/kg bolus followed by infusion at 2 mg/kg/hr) administered immediately after the injection of 0.9% saline; and lidocaine-treated rabbits (n = 8), treated identically to the endotoxemic controls with the addition of intravenous lidocaine (3 mg/kg bolus followed by infusion at 2 mg/kg/hr) administered immediately after the injection of endotoxin.

MEASUREMENTS AND MAIN RESULTS

We compared the cardiac output, systemic vascular resistance, blood gases, and plasma cytokine concentrations (tumor necrosis factor, interleukin [IL]-6, and IL-8) for each group. After endotoxin injection, the mean arterial pressure, cardiac output, and systemic vascular resistance decreased progressively in the endotoxemic controls. At 4 hrs after injection, all of the variables except the heart rate and central venous pressure were lower in the endotoxemic controls than in the other groups. At 4 hrs after endotoxin injection, both IL-6 and IL-8 concentrations increased in all groups. However, the mean concentrations of IL-6 and IL-8 in the endotoxemic controls significantly exceeded those in the other groups. No significant differences existed between the laparotomy controls and lidocaine-treated rabbits.

CONCLUSIONS

Lidocaine had a profound inhibitory effect on the hemodynamic and cytokine responses to endotoxemia when it was administered immediately after exposure to endotoxin. Our results demonstrate the potential usefulness of lidocaine as an anti-inflammatory agent in endotoxemia.

Cytokine secretion by stimulated monocytes depends on the growth phase and heat treatment of bacteria: a comparative study between lactic acid bacteria and invasive pathogens

The consumption of food containing lactic acid bacteria (LAB) has been shown to exert immunomodulatory effects in humans. The specific cellular interaction of these bacteria with immuno-competent cells has not yet been fully understood. Since the TNF-alpha secretion of stimulated monocytes is an important initial response to a bacterial challenge, we investigated the potential of LAB originating from the human intestine or fermented food in comparison to the effect of invasive pathogens. The challenge of monocytes with three LAB strains, Listeria monocytogenes or enterohaemorrhagic Escherichia coli (EHEC) elicited a strain specific, dose-dependent biphasic TNF-alpha secretion. The concentration (EDmax) of bacteria or bacterial cell wall components necessary to induce maximal TNF-alpha secretion (TNFmax) by monocytes was mathematically approximated. It was shown for exponentially growing LAB strains that the maximal TNF-alpha secretion (TNFmax) was stronger (57 to 78%) upon stimulation with living bacteria than with heat killed cells. In contrast to log-phase bacteria, the maximal TNF-alpha secretion of monocytes (TNFmax) was higher (15 to 55%) after the stimulation with heat killed, stationary-phase bacteria when compared to that of live LAB. Thus, monocyte stimulation was clearly affected by the growth phase of bacteria. Purified cell walls of LAB strains revealed only a limited potential for monocyte stimulation. LPS exhibited a higher capacity to stimulate monocytes than purified gram positive cell walls or muramyldipeptide. In comparison to pathogenic bacteria, the maximal secretory TNF-alpha response (TNFmax) was up to 2 fold higher with LAB strains. In general, the amount of bacteria (EDmax) necessary to induce maximal TNF-alpha secretion (TNFmax) was approximately 1 to 3 log higher for heat killed bacteria when compared to live bacterial cells illustrating the significant lower potential of heat killed bacteria to activate monocytes.

Interaction of cationic peptides with lipoteichoic acid and gram-positive bacteria

Compounds with antiendotoxin properties have been extensively studied for their potential as therapeutic agents for sepsis attributable to gram-negative bacteria. However, with the increasing incidence of gram-positive sepsis, there is interest in identifying compounds with a broad spectrum of action against both gram-positive and gram-negative bacteria. A series of synthetic alpha-helical cationic peptides related to bee melittin and silk moth cecropin have previously been shown to bind lipopolysaccharide (LPS) with high affinity, inhibit LPS-induced tumor necrosis factor alpha (TNF-alpha) production in vitro and in vivo, and kill gram-negative bacteria. In this study, we analyzed whether these peptides were active against gram-positive bacteria; whether they could bind to lipoteichoic acid (LTA), the major proinflammatory structure on gram-positive bacteria; and whether they could block the ability of LTA to promote the release of cytokines by the RAW 264.7 murine macrophage cell line. We found that the cationic peptides demonstrated moderate growth-inhibitory activity toward gram-positive bacteria. In addition, the peptides bound LTA with high affinity. This correlated with the ability of the peptides to block LTA-induced production of TNF and interleukin-6 by RAW 264.7 cells but did not correlate with their ability to kill the bacteria. The peptides also effectively inhibited LTA-induced TNF production in a whole human blood assay. The peptides were also able to partly block the ability of heat-killed Staphylococcus aureus, as well as soluble products of live S. aureus, to stimulate cytokine production by macrophages. Our results indicate that these cationic peptides may be useful to prevent sepsis and inflammation caused by both gram-negative and gram-positive bacteria.

Increased interleukin-1 (IL-1) and imbalance between IL-1 and IL-1 receptor antagonist during acute inflammation in experimental Shigellosis

Infection by the enteric bacterial pathogen Shigella results in intense mucosal inflammation and destruction of the colonic and rectal epithelium in infected humans. Initial bacterial translocation occurs through the follicle-associated epithelium. Previous experiments suggest that interleukin-1 (IL-1) is crucial to trigger inflammation, particularly in the follicular zones. During the first 4 hours of infection in a rabbit ligated-loop model of intestinal invasion, there are two salient characteristics: (i) a high concentration of IL-1alpha and IL-1beta, both in infected Peyer's patch tissue and in the corresponding efferent mesenteric blood, and (ii) a very low level of expression of IL-1 receptor antagonist (IL-1ra). These may reflect a combination of regulation of expression and secretion of IL-1alpha, IL-1beta, and IL-1ra by both resident and recruited phagocytes and the induction of mononuclear phagocyte apoptosis by Shigella. This low IL-1ra/IL-1 ratio likely accounts for the rapid, uncontrolled inflammation characteristic of shigellosis.

Clinical gram-positive sepsis: does it fundamentally differ from gram-negative bacterial sepsis?

OBJECTIVE

To review the basic differences between gram-positive and gram-negative sepsis and to assess the effect of these differences on current and future therapeutic strategies for sepsis.

DESIGN

Literature review of the past 30 yrs of laboratory and clinical reports that analyze the microbial aspects of sepsis and the immunologic response to systemic infection.

RESULTS

The increasing prevalence of sepsis from gram-positive bacterial pathogens necessitates reevaluation of many of the basic assumptions about the molecular pathogenesis of septic shock. It has been assumed that the initiation of the systemic inflammatory response with activation of the proinflammatory cytokine networks and other mediators results in a similar pathophysiologic process, regardless of the causative microbic pathogen. Yet, there is increasing experimental evidence that fundamental differences exist in the host response to gram-positive bacterial pathogens compared with the host response to gram-negative organisms. Systemic immune activation during sepsis may promote the clearance of the microbic pathogen; however, generalized inflammation also contributes to the pathogenesis of septic shock. The balance between these beneficial and deleterious effects may differ between gram-positive and gram-negative pathogens.

CONCLUSIONS

Results of antimediator therapies in clinical trials in septic shock are inconclusive but suggest that the response may differ, depending on the type of microbic pathogen. The immune-mediated pathophysiologic mechanisms that underlie gram-positive sepsis and the potential interactions between the infecting microorganism and efficacy of anticytokine therapies require further investigation. Treatment strategies that explain the causative organism may be necessary for optimal use of immunoadjuvants in the future.

Gram-positive sepsis. Mechanisms and differences from gram-negative sepsis

This article has reviewed the mechanisms by which gram-positive bacteria lead to septic shock, with regard to bacterial structure and toxicology and the host responses elicited both in animal models and in the clinical setting. Gram-positive organisms are better suited to invade host tissues and elicit, in general, a brisker phagocytic response than gram-negative organisms. The lack of endotoxin in the outer cell wall is compensated for by the presence of exposed peptidoglycan and a range of other toxic secreted products. It appears that cell wall components of gram-positive bacteria may signal via the same receptor as gram-negative endotoxin, although the type of signal and coreceptor may differ. Both animal and clinical data suggest that, unlike endotoxin-mediated shock, gram-positive infection produces a modest TNF response only and does not respond well to anti-TNF therapies. This leads one to conclude that the mechanisms leading to shock in gram-positive infection may be multifactorial and perhaps more difficult to treat. A thorough review of gram-positive mechanisms of sepsis is hampered by a lack of basic research in this field. Understanding of gram-negative bacterial structure and the regulation of virulence genes is at an advanced stage, yet the molecular tools to analyse virulence factors in the gram-positive genome have only recently become available. There is a paucity of good animal models of gram-positive infection and a lack of microbiologic data from some of the major trials in sepsis that might have given greater insight into the mechanisms leading to shock in various infections.

An enhancement of nitric oxide production regulates energy metabolism in rat hepatocytes after a partial hepatectomy

BACKGROUND/AIMS

Infection after a liver resection often results in hepatic failure. Nitric oxide is one of the candidates which has been suspected to cause cellular dysfunction during infection in the liver. We have previously reported that the inflammatory cytokine interleukin-1beta (IL-1beta) induced the expression of the inducible nitric oxide synthase gene in primary cultured rat hepatocytes. We hypothesized that an enhancement of nitric oxide production after the resection was implicated in a change in liver energy metabolism, thus resulting in liver dysfunction.

METHODS

In this study, we performed a 70% hepatectomy or a sham operation in rats, and then isolated hepatocytes from the remnant liver by collagenase perfusion. The cultured hepatocytes were treated with cytokines including IL-1beta. The effects on nitric oxide induction, the ATP content and ketone body ratio (acetoacetate/beta-hydroxybutyrate) were then compared between the partial hepatectomized (PH) and sham-operated (control) rats.

RESULTS

IL-1beta augmented the induction of nitric oxide production two-fold in hepatocytes from the PH rats as compared to the control rats. IL-1beta markedly decreased the ATP content in the PH rats, although IL-1beta also decreased the ATP content in the control rats, but to a lesser extent. IL-1beta also decreased the ketone body ratio in both groups. The addition of L-arginine further stimulated the inhibition of the ATP levels and the ketone body ratio concomitantly with increased nitric oxide production in the PH rats. N(G)-monomethyl-L-arginine, an inhibitor of nitric oxide synthase, abolished the effects of IL-1beta on the ATP levels and ketone body ratio, as well as on the nitric oxide production.

CONCLUSIONS

These results demonstrate that the decreased ATP content observed in PH rats resulted from an increase in nitric oxide production. The decrease in ketone body ratio indicates that nitric oxide-induced mitochondrial dysfunction contributes significantly to ATP attenuation in hepatocytes. Therefore, the regulation of nitric oxide induction may be crucial for preventing liver failure after a hepatic resection.

Additive effect of tumor necrosis factor-alpha and endotoxin on bilirubin cytotoxicity

Clinical observations suggest that sepsis may enhance the risk of kernicterus. This study investigated the combined effects of bilirubin, endotoxin, and tumor necrosis factor-alpha (TNF-alpha), which simulate sepsis in a jaundiced mouse fibroblast cell line. The horseradish peroxidase oxidation method was applied for bilirubin-albumin titration studies to test the effect of endotoxin and TNF-alpha on bilirubin-albumin binding. A modified 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide method was used to study cytotoxicity. Bilirubin caused cytotoxicity in a dose-dependent manner in the cultured mouse fibroblasts. Such an effect was significantly amplified by TNF-alpha and endotoxin. TNF-alpha and endotoxin had no effect on the bilirubin-albumin titration curves. Our results have shown that TNF-alpha and endotoxin increase the cytotoxicity of bilirubin. These findings provide supportive evidence that sepsis would increase the risk of tissue damage by bilirubin.

An inflammatory polypeptide complex from Staphylococcus epidermidis: isolation and characterization

Staphylococcus epidermidis releases factors that activate the HIV-1 long terminal repeat, induce cytokine release, and activate nuclear factor B in cells of macrophage lineage. The active material had a mass of 34,500 daltons, was inactivated by proteases and partitioned into the phenol layer on hot aqueous phenol extraction, and thus was termed phenol-soluble modulin (PSM). High performance liquid chromatography (HPLC) of crude PSM yielded two peaks of activity designated PSM peak 1 and peak 2. MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) mass spectroscopy indicated the presence of two components in peak 1, which were designated PSM and PSM. Peak 2 contained a single component, designated PSM. Separation of PSM and PSM in peak 1 could be achieved by a second HPLC procedure. The structure of each component was determined by amino acid sequence analysis and identification and sequencing of their genes. PSM, PSM, and PSM were 22-, 44-, and 25-amino acid, respectively, strongly hydrophobic polypeptides. PSM was identified as Staphylococcus epidermidis delta toxin, whereas PSM and PSM exhibited more distant homology to previously described staphylococcal toxins. They appeared to exist as a complex or aggregate with activity greater than the component parts. The properties of the S. epidermidis PSMs suggest that they may contribute to the systemic manifestations of Gram-positive sepsis.

Tumor necrosis factor-alpha production after esophageal cancer surgery: differences in the response to lipopolysaccharide stimulation among whole blood, pleural effusion cells, and bronchoalveolar lavage fluid cells

The body's defense mechanism in response to stress may appear to be the sum of activation and suppression. We investigated chronological changes in tumor necrosis factor-alpha (TNF-alpha) production by local effusion cells and whole blood of esophageal cancer patients who had undergone radical resection. Whole blood, pleural effusion cells, and bronchoalveolar lavage fluid (BALF) cells were obtained from the 20 patients. Whole blood was stimulated with Escherichia coli (1 microg/ml), Staphylococcus aureus (10 microg/ml), and lipopolysaccharide (LPS) (1 microg/ml), and pleural effusion cells and BALF cells were stimulated with LPS; 24-H incubation and TNF-alpha concentration in supernate was measured by enzyme-linked immunosorbent assay (ELISA). Within 3 h after starting the operation, TNF-alpha production in whole blood was significantly (P < 0.05) decreased compared with preoperative value by each stimulation, and this suppression persisted up to day 3. These reductions in postoperative TNF-alpha production correlated with intraoperative hemorrhage. On the other hand, the LPS-induced release of TNF-alpha into pleural effusion cells and BALF cells were markedly increased during the study period. These results indicate that large quantities of cytokines are produced by a second attack, such as infection, in areas where immunocytes accumulate. We believe that the body reacts to surgical stress in a variety of ways. Circulating blood and immunocytes that accumulate in damaged organs are thought to react very differently to stress.