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

Lipoteichoic acid, a cell wall component of Gram-positive bacteria, induces sleep and fever and suppresses feeding

Fragments of the bacterial cell wall are bioactive microbial molecules that have profound effects on the function of the brain. Some of the cell wall constituents are common to both Gram-positive and Gram-negative bacteria, e.g., peptidoglycans, while other cell wall components are specific to either Gram-positive or Gram-negative microbes. Lipopolysaccharide (LPS), also called endotoxin, is found exclusively in Gram-negative bacteria, while lipoteichoic acid (LTA) is specific to Gram-positive bacteria. The effects of peptidoglycans, their fragments, and LPS are well characterized, they induce sleep, fever and anorexia. In the present study, we investigated the sleep, body temperature and food intake modulating effects of LTA. We found that intraperitoneal injection of 100 and 250 μg LTA from B. subtilis and S. aureus increases non-rapid-eye movement sleep (NREMS) in mice. The effects were dose-dependent, and the changes were accompanied by decreased motor activity and feeding as well as febrile responses. Intraperitoneal injection of 10 μg LTA induced monophasic increases in body temperature, while 100 and 250 μg LTA from B. subtilis induced initial hypothermia followed by fever. Treatment with 250 μg LTA from S. aureus elicited monophasic hypothermia. Administration of 300 μg/kg LTA from S. aureus directly into the portal vein elicited similar sleep responses in rats but did not affect body temperature. The sleep-modulating effects of LTA were similar to that of LPS in mice, although LTA appears to be less potent. These findings suggest that the role of LTA in signaling by Gram-positive bacteria in the host body is analogous to the role of LPS/endotoxin in signaling by Gram-negative microbes. LTA may play a role in the development of sickness response in clinically manifest Gram-positive bacterial infections and may contribute to sleep signaling by the commensal intestinal microbiota.

Effect of LPS and LTA stimulation on the expression of TLR-pathway genes in PBMCs of Akkaraman lambs in vivo

This is the first study investigating the changes in some gene expressions related to the TLR pathway in vivo in sheep. Lipopolysaccharide (LPS) and lipoteichoic acid (LTA) molecules were administrated separately and in combination to the Akkaraman lambs via intranasal route. For this purpose, 28 lambs were distributed into four groups (LPS, LTA, LPS + LTA, and control, n = 7). Blood samples were collected to isolate the peripheral blood mononuclear cells (PBMCs) at 24 h and on day 7. Expression levels of TLR2, TLR4, MyD88, TRAF6, TNF-α, IL-1ß, IL-6, IL-10, NF-κß, and IFN-γ genes were determined by qRT-PCR. Increases were determined in the expression data of TLR2 [LPS (P < 0.05) and LTA + LPS (P < 0.01)], TLR4 [LTA + LPS (P < 0.05)], TNF-α, IL-10 [LTA + LPS (P < 0.05)], and IFN-γ genes in all groups in the mRNA expression analysis of PBMCs isolated at 24 h whereas decreases were determined in the expression levels of these genes on day 7. The combination of LPS + LTA stimulated lamb PBMCs more effectively than separate administration of LPS and LTA at 24 h. Therefore, this article may contribute to the understanding the host-pathogen interaction of respiratory-transmitted bacterial diseases concerning PBMCs at 24 h and on day 7. Also this study may contribute to the dose adjustment for bacterial vaccine studies in sheep. Experimental application doses will be helpful for in vivo and in vitro drug and vaccine development studies in the fields of pharmacology and microbiology.

Pathogenic Mechanisms and Host Interactions in Staphylococcus epidermidis Device-Related Infection

Staphylococcus epidermidis is a permanent member of the normal human microbiota, commonly found on skin and mucous membranes. By adhering to tissue surface moieties of the host via specific adhesins, S. epidermidis is capable of establishing a lifelong commensal relationship with humans that begins early in life. In its role as a commensal organism, S. epidermidis is thought to provide benefits to human host, including out-competing more virulent pathogens. However, largely due to its capacity to form biofilm on implanted foreign bodies, S. epidermidis has emerged as an important opportunistic pathogen in patients receiving medical devices. S. epidermidis causes approximately 20% of all orthopedic device-related infections (ODRIs), increasing up to 50% in late-developing infections. Despite this prevalence, it remains underrepresented in the scientific literature, in particular lagging behind the study of the S. aureus. This review aims to provide an overview of the interactions of S. epidermidis with the human host, both as a commensal and as a pathogen. The mechanisms retained by S. epidermidis that enable colonization of human skin as well as invasive infection, will be described, with a particular focus upon biofilm formation. The host immune responses to these infections are also described, including how S. epidermidis seems to trigger low levels of pro-inflammatory cytokines and high levels of interleukin-10, which may contribute to the sub-acute and persistent nature often associated with these infections. The adaptive immune response to S. epidermidis remains poorly described, and represents an area which may provide significant new discoveries in the coming years.

The hepatocyte as a microbial product-responsive cell

Much research has focused on the responses to microbial products of immune cells such as monocytes, macrophages, and neutrophils. Although the liver is a primary response organ in various infections, relatively little is known about the antimicrobial responses of its major cell type, the hepatocyte. It is now known that the recognition of bacteria occurs via cell-surface proteins that are members of the Toll-like receptor (TLR) family. In addition, lipopolysaccharide (LPS) is bound by circulating LPS-binding protein (LBP) and presented to cell-surface CD14, which in turn interacts with TLR and transduces an intracellular signal. We investigated the CD14 and TLR2 responses of whole liver and isolated hepatocytes, and demonstrated that these cells can be induced to express the molecules necessary for responses to both Gram-positive and Gram-negative bacteria. Our findings may have clinical implications for pathological states such as sepsis.

Differential susceptibility of rhesus monkeys to high doses of endotoxin

We investigated susceptibility of rhesus monkeys ( Macaca mulatta) to Escherichia coli endotoxin (ETX) in two ways. We infused 8 monkeys (group A) with various doses of ETX (1.0-7.5 mg/kg) to assess the effect of dose on shock severity; and we infused 6 monkeys (group B) with 1.0 mg ETX/kg to test biological variability to ETX challenge. Controls were 7 saline-infused monkeys. Systolic pressure, heart rate (HR), temperature, plasma ETX and inflammatory markers — tumor necrosis factor-α (TNF), interleukin-1 (IL-1) and IL-6 — were quantified before and at 1.5, 2.5, 6 and 26 h after infusion. The highest plasma concentrations of ETX (at 1.5 h) — < 8% that infused — correlated well with the infused doses. ETX elicited hypotension and increases in HR in all monkeys. Fever did not occur. The degree of hypotension and increase in HR and death did not correlate with ETX dose (or plasma ETX concentrations). The response of inflammatory cytokines to ETX was greater in nonsurvivors than in survivors. The observed low mortality rate (4/14) suggests that rhesus monkeys are rather resistant to high endotoxin concentrations similar to baboons but unlike humans or chimpanzees. The lack of correlation between ETX dose and shock severity suggests that there is a critical ETX concentration in each animal that leads to controllable or uncontrollable cytokine elevation in plasma, with reversible or irreversible shock, and resulting survival or death.

Cross-tolerance between bacterial endotoxin and group B Streptococcus in neonatal rats

Although endotoxin tolerance can be induced in newborns, potential cross-tolerance to group B Streptococcus (GBS), a common Gram-positive neonatal pathogen has not been investigated. In the present study we tested the hypothesis that endotoxin or recombinant tumor necrosis factor (rTNFα) can induce tolerance to lethal injection of heat-killed GBS in rat newborn pups and vice versa. The effect of such cross-tolerance on endogenous generation of plasma TNFα was subsequently evaluated. Rat pups (18-24 h old) were pretreated intracardially (i.c.) with either phosphate buffered saline (PBS), Salmonella enteritidis endotoxin (30 μg/kg) or rTNFα (35, 70 or 140 μg/kg). The pups were pretreated for either 4, 24, 48, 96 or 240 h prior to a lethal heat-killed GBS challenge. The susceptibility of the neonates to GBS-induced mortality was dependent on the duration of the pretreatment period. At 4 h of pretreatment with endotoxin or TNF, GBS-induced mortality was augmented relative to the PBS group. However, by 24-48 h the endotoxin and TNF pretreated neonates became more resistant to GBS-induced mortality. In a converse of the above experiment, neonates were pretreated with heat killed GBS (0.7 mg/kg) or rTNFα (70 μg/kg) and sensitivity to endotoxin was determined at 4-240 h after pretreatment. The data were qualitatively similar to endotoxin pretreatment. The 4 h GBS or TNF pretreatment rendered the neonates more susceptible to endotoxin-induced mortality. However, by 24-48 h the pretreatment groups were more resistant (P < 0.05) to endotoxin than the PBS controls. Plasma TNFα levels were increased (P < 0.05) 2 h after challenge i.c. with lethal heat-killed GBS or S. enteritidis endotoxin. In the 4 h pretreatment groups that received either GBS or endotoxin and then challenged with endotoxin or GBS, respectively, the plasma TNFα response was markedly augmented (P < 0.05). By 48 h of pretreatment, however, the plasma TNFα response in these groups to the stimuli was significantly reduced (P < 0.05) compared to the PBS pretreated groups. Therefore, plasma TNFα parallels lethality induced by GBS or endotoxin pretreatment. The ability of GBS and endotoxin to induce cross tolerance suggests that common pathophysiological pathways are involved in these syndromes.

A comparative study of biological activities of lipoteichoic acid and lipopolysaccharide

Lipoteichoic acids (LTAs) of Gram-positive bacteria and lipopolysaccharide (LPS) are structurally similar and share several biological activities. In this study, the capacity of LTAs for inducing the cell surface expression of adhesion molecules ICAM-1, VCAM-1, and ELAM-1 by HUVEC were investigated and compared to that of LPS. In the presence of serum, LTA from Staphylococcus aureus, Streptococcus sanguis, Streptococcus pyogenes and Streptococcus mutans dose-dependently stimulated adhesion molecule expression above control levels although they were 100-1000 times less potent than LPS. LTA from Streptococcus faecalis and Bacillus subtilis had no effects. Similar to LPS, the activity of the LTAs was dose-dependently inhibited by polymyxin B, whereas unlike LPS, LTA activity decreased in the presence of triethylamine. The LTAs also exhibited reactivity in the Limulus amebocyte lysate (LAL) assay correlating with their ability to induce ICAM-1 expression. However, their LAL reactivity was approximately 3-6 orders of magnitude less than that of LPS. Furthermore, LTA-stimulated ICAM-1 expression was serum-dependent and inhibited by anti-CD14 antibody, 63D3. Thus, LTA shares several properties with LPS including inhibition by polymyxin B, reactivity in the LAL assay, and stimulation of endothelial cells via a CD14-dependent mechanism. These results suggests a possible role for LTAs in the inflammatory response due to infections with Gram-positive bacteria.

Variation of Circulating Inflammatory Mediators in Staphylococcus aureus and Escherichia coli Bloodstream Infection

Background

The aim of this study was to examine the behavior of circulating inflammatory mediators and to exclude gram-positive from gram-negative bloodstream infections. Results may be helpful in selection of optimal specific antibiotic therapies.

Material/Methods

Mice (25–27 g) were randomized to 3 groups infected with Staphylococcus aureus (S. aureus) ATCC 25923, Escherichia coli (E. coli) ATCC 25922, or phosphate-buffered saline (PBS). The white blood cell count (WBC) and the concentrations of serum C-reactive protein (CRP), procalcitonin (PCT), interleukin (IL)-1α, IL-1β, IL-6, IL-10, monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1α (MIP-1α) were detected in blood samples at different time intervals after intravenous tail injection.

Results

The results showed that compared to the control mice, infected animals exhibited significantly higher levels of all mediators after bacterial infection. Moreover, compared to the mice that received S. aureus, animals with E. coli infection showed significantly greater increases in serum IL-1α, IL-1β, IL-6, MCP-1, and MIP-1α levels.

Conclusions

These results suggest that the use of the analyzed serum markers at an early stage of bloodstream infection may give useful information for the clinician to distinguish gram-negative from gram-positive infections.

Betulin attenuates lung and liver injuries in sepsis

Sepsis is a complex condition with unacceptable mortality. Betulin is a natural extract with multiple bioactivities. This study aims to evaluate the potential effects of betulin on lung and liver injury in sepsis. Cecal ligation and puncture was used to establish the rat model of sepsis. A single dose of 4mg/kg or 8mg/kg betulin was injected intraperitoneally immediately after the model establishment. The survival rate was recorded every 12h for 96h. The organ injury was examined using hematoxylin and eosin staining and serum biochemical test. The levels of proinflammatory cytokines and high mobility group box 1 in the serum were measured using ELISA. Western blotting was used to detect the expression of proteins in NF-κB and MAPK signaling pathways. Betulin treatment significantly improved the survival rate of septic rats, and attenuated lung and liver injury in sepsis, including the reduction of lung wet/dry weight ratio and activities of alanine aminotransferase and aspartate aminotransferase in the serum. In addition, levels of tumor necrosis factor-α, interleukin-1β, interleukin-6 and high mobility group box 1 in the serum were also lowered by betulin treatment. Moreover, sepsis-induced activation of the NF-κB and MAPK signaling pathway was inhibited by betulin as well. Our findings demonstrate the protective effect of betulin in lung and liver injury in sepsis. This protection may be mediated by its anti-inflammatory and NF-κB and MAPK inhibitory effects.

Differential induction of inflammatory cytokines and reactive oxygen species in murine peritoneal macrophages and resident fresh bone marrow cells by acute staphylococcus aureus infection: contribution of toll-like receptor 2 (TLR2)

Among the known Toll-like receptors (TLRs), Toll-like receptor 2 (TLR2) is a key sensor for detecting Staphylococcus aureus invasion. But the function of TLR2 during S. aureus infection in different cell populations is unclear. Two different cell subtypes were chosen to study the interaction of S. aureus with TLR2 because macrophages are extremely different from one compartment to another and their capacity to respond to live bacteria or bacterial products differs from one site to another. The contribution of TLR2 to the host innate response against acute live S. aureus infection and heat-killed S. aureus (HKSA) using anti-TLR2 antibody in murine peritoneal macrophages and resident fresh bone marrow cells has been investigated here. TLR2 blocking before infection induces the release of interleukin (IL)-10 by macrophages thereby inhibiting excessive production of oxidants by activating antioxidant enzymes. TLR2-blocked peritoneal macrophages showed impaired release of tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ) and IL-6 in response to both live and heat-killed S. aureus infection except bone marrow cells. TLR2-mediated free radical production and killing of S. aureus were modulated by TLR2 blocking in peritoneal macrophages and resident bone marrow cells. This study supported that S. aureus persists in resident bone marrow cells in a state of quiescence.

Lipoteichoic acid modulates inflammatory response in macrophages after phagocytosis of titanium particles through Toll-like receptor 2 cascade and inflammasomes

Toll-like receptor 2 (TLR2) and nucleotide-binding and oligomerization domain-like receptors with a pyrin domain 3 (NLRP3) inflammasomes have been presumed to participate in the pathogenesis of aseptic implant loosening. The aim of this study is to analyze the cellular localization of TLR2 and NLRP3 inflammasomes in the periprosthetic tissue from aseptically loose hip implants as well as the expression of these molecules in macrophages stimulated in vitro with titanium particles (Ti) coated with lipoteichoic acid (LTA). Using immunohistochemistry, immunoreactivity of TLR2 and NLRP3 inflammasomes was found in macrophages within the foreign body granulomatosis. Using RAW264.7 cells, stimulation with Ti increased the messenger RNA (mRNA) levels of TLR2 and TNF-α. Stimulation with LTA-coated Ti enhanced mRNA levels of NLRP3 and IL-1β, whereas reinforced secretion of IL-1β was not detected in spite of marked release of TNF-α. Finally, the same cells with silenced Irak2, an adaptor protein in the TLR2 cascade, suppressed this NLRP3 upregulation. This study suggests that TLR2 and NLRP3 inflammasomes are factors involved in cross-talk mediating the foreign body type response to wear particles. In addition, discrepant behavior in the release between TNF-α and IL-1β release may explain the variable pathomechanisms of aseptic implant loosening without acute inflammatory reactions.

Upregulation of Polymeric Immunoglobulin Receptor Expression by the Heat-Inactivated Potential Probiotic Bifidobacterium bifidum OLB6378 in a Mouse Intestinal Explant Model

We determined whether a potential probiotic bacterium, Bifidobacterium bifidum OLB6378 (BB6378), exerts beneficial effects on the mucosal immune system in a mouse intestinal explant model. The addition of heat-inactivated BB6378 to intestinal explants prepared from embryonic day 18 BALB/c mice increased the expression of polymeric immunoglobulin receptor (pIgR) mRNA by two- to fivefold. These effects were observed on ileal and colonic explants but not on jejunal explants, suggesting that the BB6378-induced pIgR upregulation is site-specific within the mouse intestine. The upregulation of pIgR protein expression in colonic explants was also detected after 24 h of culture. The results of DNA microarray analysis of ileal and colonic samples indicated that BB6378 increased the gene expression of interleukin (IL)-1α and IL-1β, and IL-1α content in colonic explants was significantly increased after 20 h of culture with BB6378. We then examined the involvement of endogenously induced IL-1α in pIgR mRNA upregulation by using IL-1α knockout (KO) mice. Contrary to our expectations, pIgR mRNA expression was equally upregulated by BB6378 in colonic explants from BALB/c and IL-1α KO mice. Conversely, we examined the involvement of Toll-like receptors in pIgR mRNA upregulation by using MyD88 KO mice. The upregulation of pIgR was completely suppressed in the explants derived from MyD88 KO mice. Taken together, we conclude that in a mouse intestinal explant model, the heat-inactivated potential probiotic BB6378 increases intestinal pIgR expression in a site-specific manner and that the upregulation of pIgR could be explained by a direct microbial effect on the epithelium via Toll-like receptors.

Dexmedetomidine controls systemic cytokine levels through the cholinergic anti-inflammatory pathway

Previous studies have shown that dexmedetomidine exerted anti-inflammatory effect on several animal models with inflammation, but the mechanism is not clear. This study intends to elucidate the anti-inflammatory mechanism of dexmedetomidine through the cholinergic anti-inflammatory pathway. To investigate this therapeutic potential of dexmedetomidine, a murine model of endotoxemia was established induced by lipopolysaccharide (LPS). Animals were assigned to one of four protocols. Protocol one: animals were randomly assigned to control group, dexmedetomidine group, and sterile saline group (n=20 each), and these animals were used for survival analysis. The survival rate was assessed up to 120 h after endotoxin injection. Protocol two: animals were randomly assigned to one of four groups (n=16 each): group 1 (group Saline), treated with sterile saline 15 min prior to endotoxin treatment (10 mg kg(-1) over 2 min); group 2 (group Dex), treated with dexmedetomidine 15 min prior to endotoxin treatment; group 3 (group αBGT+Dex), treated with alpha-7 nicotinic acetylcholine receptors (α7nAChR) antagonist alpha-bungarotoxin (αBGT, 1 μg/kg) 15 min prior to dexmedetomidine treatment; group 4 (group saline+Dex), treated with equivalent sterile saline 15 min prior to dexmedetomidine treatment. Protocol three: animals were randomly assigned to one of two groups (n=16 each): vagotomy group (group VNX+Dex), right cervical vagus nerve was exposed and transected; sham-operated group (group SHAM+Dex), the cervical vagus nerve was visualized, but was neither isolated from the surrounding tissues nor transected. Protocol four: animals were treated with dexmedetomidine (40 μg/kg) and sterile saline to observe the discharge activity of cervical vagus nerves by using BL-420F data acquisition and analysis system (n=16 each). In the survival analysis groups, the survival rate of dexmedetomidine group was significantly higher than that of the endotoxemia group (65 versus 25 %, P<0.01). Preemptive administration of dexmedetomidine significantly attenuated the cytokine response after lipopolysaccharide (LPS) induced endotoxemia (TNF-alpha, IL-1beta, IL-6, P<0.01, respectively). However, preemptive administration of dexmedetomidine failed to suppress cytokine response in α-bungarotoxin group and vagotomy group (TNF-alpha, IL-1beta, IL-6, P>0.05, respectively). Furthermore, preemptive administration of dexmedetomidine significantly increased the discharge frequency of cervical vagus nerves in comparison with sterile saline treatment (P<0.01).Our results demonstrate that the preemptive administration of dexmedetomidine increases the activity of cervical vagus nerve and have the ability to successfully improve survival in experimental endotoxemia by inhibiting the inflammatory cytokines release. However, administration of dexmedetomidine to vagotomy or α7 nAChR antagonist pretreatment mice failed to suppress TNF levels, indicating that the vagus nerve and α7nAChR-mediated cholinergic anti-inflammatory pathway is required for the anti-inflammatory effect of dexmedetomidine. These findings show that central alpha-2 agonist dexmedetomidine suppresses systemic inflammation through vagal- and α7nAChR-dependent mechanism.

The effect of dexmedetomidine on inflammatory response of septic rats

Background

Some studies have demonstrated dexmedetomidine has anti-inflammatory effect on septic rats. However, the mechanism of how dexmedetomidine exerts these effects is still remained unknown. This study was designed to investigate the mechanism of how dexmedetomidine inhibits the production of inflammatory mediators in cecal ligation and puncturinduced septic rats.

Methods

48 Sprague-Dawley rats were randomly divided into six groups: sham-operated (sham) group, cecal ligation and puncture (CLP) group, dexmedetomidine 5 μg/kg (DEX5) group, dexmedetomidine 10 μg/kg (DEX10) group,dexmedetomidine + yohimbine (DEX10 + Yoh) group and yohimibine group (Yoh). Blood, bronchoalveolarlavage fluid (BALF) and lung tissues in each group were collected at six hours after dexmedetomidine or yohimbine treatment,. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in BALF and plasma were measured by enzyme-linked immunosorbent assay (ELISA). Toll-like receptor-4(TLR4) and myeloid differerntiation factor(MyD88) expression were measuredby quantitative PCR, and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation were determined by western blott.

Results

Compared with CLP group, dexmedetomidine significantly decreased not only the production of TNF-α and IL-6 both in plasma and BALF, but also inhibited the expression of TLR4 and MyD88 in mRNA level and the activation of ERK1/2 and NF-κB in the lung tissues of CLP-induced septic rats. All these effects could not be reversed by yohimibine.

Conclusions

Dexmedetomidine treatment can effectively reduce the generation of inflammatory mediators in the plasma and BALF of CLP-induced septic rats. These effects of dexmedetomidine rely on TLR4/MyD88/MAPK/ NF-κB signaling pathway and are independent of α₂-adrenoceptor.

Dexmedetomidine inhibits inflammatory reaction in lung tissues of septic rats by suppressing TLR4/NF-κB pathway

Dexmedetomidine has been reported to reduce mortality in septic rats. This study was designed to investigate the effects of dexmedetomidine on inflammatory reaction in lung tissues of septic rats induced by CLP. After induction of sepsis, the rats were treated with normal saline or dexmedetomidine (5, 10, or 20 μg/kg). The survival rate of septic rats in 24 h was recorded. The inflammation of lung tissues was evaluated by HE stain. The concentrations of IL-6 and TNF-α in BALF and plasma were measured by ELISA. The expressions of TLR4 and MyD88 were measured by western blotting. The activation of NF-κB in rat lung tissues was assessed by western blotting and immunohistochemistry. It was found that the mortality rate and pulmonary inflammation were significantly increased in septic rats. IL-6 and TNF-α levels in BALF and plasma, NF-κB activity, and TLR4/MyD88 expression in rat lung tissues were markedly enhanced after CLP. Dexmedetomidine (10 and 20 μg/kg) significantly decreased mortality and pulmonary inflammation of septic rats, as well as suppressed CLP-induced elevation of TNF-α and IL-6 and inhibited TLR4/MyD88 expression and NF-κB activation. These results suggest that dexmedetomidine may decrease mortality and inhibit inflammatory reaction in lung tissues of septic rats by suppressing TLR4/MyD88/NF-κB pathway.

Effects of dexmedetomidine on early and late cytokines during polymicrobial sepsis in mice

OBJECTIVE

We investigated whether dexmedetomidine provided protective effects on cecal ligation and puncture (CLP)-induced septic mice, through suppressing the expression of pro-inflammatory cytokines [tumor necrosis factor-α (TNF-α) and interlukin-6 (IL-6)] and high mobility group box 1 (HMGB1).

METHODS

The model of sepsis was set up by CLP in 136 male BALB/c mice (40 mice for survival studies and 96 for cytokine studies) which were divided into four groups, including a C, CLP, DEX + CLP and CLP + DEX group. The serum levels of TNF-α, IL-6 and HMGB1 were detected at 6, 12, 24 and 48 h after operations, and lung HMGB1 mRNA were analyzed at 24 and 48 h. The mortality rates were calculated 7 days after the operations.

RESULTS

The mortality rates 7 days after operations were significantly lower in the CLP + DEX (50 %) and DEX + CLP (30 %) groups than in the CLP group (90 %). Serum concentrations of IL-6 and TNF-α decreased significantly in dexmedetomidine administration groups compared with the CLP group. The levels of HMGB1 and lung HMGB1 mRNA were lower in the dexmedetomidine administration groups than in the CLP group. There was a significant correlation between lung HMGB1 mRNA and serum HMGB1(r = 0.858).

CONCLUSIONS

Dexmedetomidine could reduce the mortality rate and inhibit pro-inflammatory cytokine responses during polymicrobial sepsis in mice.

The role of complement system in septic shock

Septic shock is a critical clinical condition with a high mortality rate. A better understanding of the underlying mechanisms is important to develop effective therapies. Basic and clinical studies suggest that activation of complements in the common cascade, for example, complement component 3 (C3) and C5, is involved in the development of septic shock. The involvement of three upstream complement pathways in septic shock is more complicated. Both the classical and alternative pathways appear to be activated in septic shock, but the alternative pathway may be activated earlier than the classical pathway. Activation of these two pathways is essential to clear endotoxin. Recent investigations have shed light on the role of lectin complement pathway in septic shock. Published reports suggest a protective role of mannose-binding lectin (MBL) against sepsis. Our preliminary study of MBL-associated serine protease-2 (MASP-2) in septic shock patients indicated that acute decrease of MASP-2 in the early phase of septic shock might correlate with in-hospital mortality. It is unknown whether excessive activation of these three upstream complement pathways may contribute to the detrimental effects in septic shock. This paper also discusses additional complement-related pathogenic mechanisms and intervention strategies for septic shock.

Escherichia coli K1-induced cytopathogenicity of human brain microvascular endothelial cells

Pathophysiology of Escherichia coli sepsis is complex involving circulating bacterial products, cytokine release, and sustained bacteremia resulting in the damage of vascular endothelium. Here, it is shown that E. coli K1 produced cytopathogenicity of human brain microvascular endothelial cells (HBMEC), that constitute the blood-brain barrier. Whole bacteria or their conditioned medium produced severe HBMEC damage suggesting E. coli K1-cytopathogenicity is a contact-independent process. Using lipopolysaccharide (LPS) inhibitor, polymyxin B, purified LPS extracted from E. coli K1 as well as LPS mutant derived from E. coli K1, we showed that LPS is not the sole determinant of E. coli K1-mediated HBMEC death. Bacterial product(s) for HBMEC cytopathogenicity was heat-labile suggesting LPS-associated proteins. Several isogenic gene-deletion mutants (ΔompA, ΔibeA, ΔibeB, Δcnf1) exhibited HBMEC cytopathogenicity similar to that produced by wild type E. coli K1. E. coli K1-mediated HBMEC death was independent of phosphatidylinositol 3-kinase (PI3K) but dependent partially on focal adhesion kinase (FAK) using HBMEC expressing dominant negative FAK and PI3K.

Macular infarction secondary to Staphylococcus epidermidis infection

PURPOSE

To describe a patient with macular infarction caused by Staphylococcus epidermidis-induced endophthalmitis.

METHODS

Case report.

RESULTS

An 88-year-old woman was referred to our clinic for endophthalmitis after cataract extraction. She was diagnosed to have an S. epidermidis infection. Her vision dropped from 20/50 to hand motions. During the course of her infection, she developed multiple multifocal branch retinal artery occlusions associated with absolute capillary nonperfusion centrally and was diagnosed with macular infarction.

CONCLUSION

Although most commonly associated with aminoglycoside toxicity, macular infarction can occur after endophthalmitis treatment without the use of aminoglycosides.

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

Association of tumor necrosis factor β genetic polymorphism and sepsis susceptibility

The association of the tumor necrosis factor β (TNF-β) Nco1 genetic polymorphism with susceptibility to sepsis was evaluated in 60 consecutive patients diagnosed with sepsis and in 148 healthy blood donors. Genomic DNA was extracted from peripheral blood cells and a 782 base-pair fragment of the TNF-β gene was amplified by PCR. The PCR products were subjected to Nco1 restriction digestion and analysed by restriction fragment length polymorphism analysis. Tumor necrosis factor α (TNF-α) and the C-reactive protein (CRP) serum levels were also determined by ELISA and nephelometry, respectively. Among the septic patients, the allelic frequencies of TNFB1 and TNFB2 were 0.2833 and 0.7166, respectively, and they differed from those observed in the blood donors (p=0.0282). The TNFB2 allele frequency was higher in the septic patients than in the blood donors [odds ratio=1.65 (CI 95% 1.02-2.69), p=0.0315]. The TNF-α and CRP serum levels and the APACHE II and SOFA clinical scores did not differ in the patients with the TNFB1 or TNFB2 alleles (p>0.05). The results suggest that the TNFB2 allele is associated with susceptibility to sepsis, but it was not found to be associated with the immunological and clinical biomarkers of the disease.

Fulminant liver failure model with hepatic encephalopathy in the mouse

AIM

To develop a reliable murine model for fulminant liver failure (FLF).

MATERIAL AND METHODS

We treated three groups of male C57BL/6 mice:as controls, with azoxymethane (AOM), and with galactosamine (Gal) and tumor necrosis factor-alpha (TNFα). Effects of body temperature (BT) control on survival, in all three groups were investigated. Using BT control, survival, histopathological findings and biochemical/coagulation profiles were compared between the experimental groups. Effects of hydration on international normalized ratios of prothrombin time (PT-INR) were also checked. Dose-dependent survival curves were made for both experimental groups. Neurological behaviors were assessed using a coma scale.

RESULTS

No unexpected BT effects were seen in the control group. The AOM group, but not the Gal+TNFα group, showed significant differences in survival curves between those with and without BT care. Histopathological assessment showed consistent FLF findings in both experimental groups with BT care. Between the experimental groups, there were significant differences in aspartate aminotransferase levels and PT-INR; and significant differences in PT-INRs between sufficiently- and insufficiently-hydrated groups. There were significant differences between FLF models, in the duration of each coma stage, with significant differences in stages 1 and 3 as percentages of the diseased state (stages 1-4). The two FLF models with BT care showed different survival curves in the dose-dependent survival study.

CONCLUSION

Azoxymethane can provide a good FLF model, but requires a specialized environment and careful BT control. Other FLF models may also be useful, depending on research purpose. Thoughtful attention to caregiving and close observation are indispensable for successful FLF models.

Effect of amnion derived stem cells on inflammatory response in endotoxemic rats

BACKGROUND

Systemic inflammatory response syndrome (SIRS) and sepsis are one among the most common causes of death in intensive care units. Tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-10 (IL-10) increase during SIRS and sepsis. Recent studies have demonstrated that amnion derived stem cells have anti-inflammatory effects, low immunogenicity and pluripotency. In addition, there is little ethical objection to the use of amnion derived stem cells. Here, the author presents the first study demonstrating the therapeutic potential for the use of amnion derived stem cells in a rat model of SIRS and sepsis.

METHODS

Amnion derived stem cells were isolated from amnion obtained from an uncomplicated Cesarean section and cultured. SIRS and sepsis were induced in rats by lipopolysacchride (15 mg/kg, LPS), and amnion derived stem cells were then transplanted intravenously. The heart rate, mean arterial pressure and the concentration of TNF-alpha, IL-6 and IL-10 were assessed at baseline and 2 hours and 4 hours after procedure.

RESULTS

The changes of heart rate and mean arterial pressure were reduced in the amnion derived stem cells transplanted group. In addition, increases in the plasma concentration of TNF-alpha, IL-6 and IL-10 were attenuated in the amnion derived stem cells transplanted group.

CONCLUSIONS

This study demonstrated that amnion derived stem cells attenuate inflammatory response during SIRS and sepsis. Transplantation of amnion derived stem cells can be a novel cell based therapeutic strategy for SIRS and sepsis.

Differential requirement for the activation of the inflammasome for processing and release of IL-1beta in monocytes and macrophages

The processing of pro-interleukin-1beta depends on activation of caspase-1. Controversy has arisen whether Toll-like receptor (TLR) ligands alone can activate caspase-1 for release of interleukin-1beta (IL-1beta). Here we demonstrate that human blood monocytes release processed IL-1beta after a one-time stimulation with either TLR2 or TLR4 ligands, resulting from constitutively activated caspase-1 and release of endogenous adenosine triphosphate. The constitutive activation of caspase-1 depends on the inflammasome components, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and NALP3, but in monocytes caspase-1 activation is uncoupled from pathogen-associated molecular pattern recognition. In contrast, macrophages are unable to process and release IL-1beta solely by TLR ligands and require a second adenosine triphosphate stimulation. We conclude that IL-1beta production is differentially regulated in monocytes and macrophages, and this reflects their separate functions in host defense and inflammation.

The descrease of the in vitro proliferative response of zinc-treated stressed mice's thymic lymphocytes

Prolonged stimulation of newborn mice by intraperitoneal injections with inactivated staphylococci induces a chronic neonatal inflammatory reaction and an associated oxidative-stress response. The chronically stimulated animals exhibit anorexy. show a reduction in their body weight and undergo a depression in both antibody synthesis andin vitro proliferativc response of Con A-stimulated splenic T-lymphocytes. These stressed animals also develop adrenal hyperplasia, hypozincamia and thymic hypoplasia. Despite this stress-mediated thymic involution, Con-A stimulated T-lymphocytes from thymus displayed increased theirin vitro proliferative response. Results of the present work show that intramuscular injections of zinc acetate in stressed mice, one single dose (5 microg) every other day for two weeks, reduce both the zinc concentration in the thymus gland and thein vitro proliferative response of their Con A-stimulated T-lymphocytes. The results suggest that prophylactic administration of zinc can have benefical consequences on the immunity of chronically stressed mice.

Apolipoprotein A-I diminishes acute lung injury and sepsis in mice induced by lipoteichoic acid

Lipoteichoic acid (LTA), as a primary immunostimulus, triggers the systematic inflammatory responses. Our hypothesis is that ApoA-I can neutralize LTA toxicity, like its effect on LPS. BALB/c mice were challenged with LTA, followed by human ApoA-I administration. We found that ApoA-I could attenuate LTA-induced acute lung injury and inflammation and significantly inhibit LTA-induced IL-1beta and TNF-alpha accumulation in the serum (P<0.01 and P<0.05, respectively), as well as in bronchoalveolar lavage (BAL) fluid (P<0.01 and P<0.05, respectively). Moreover, ApoA-I could significantly reduce the L-929 cell mortality caused by LTA-activated macrophages in a dose-dependent fashion. Furthermore, ApoA-I treatment could diminish LTA-mediated NFkappaB nuclear translocation in macrophages. An in vitro binding assay indicated that ApoA-I can bind LTA. These results clearly indicated that ApoA-I can effectively protect against LTA-induced sepsis and acute lung damage. The mechanism might be related to the binding and neutralization of LTA.

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

PURPOSE

We previously found that propofol attenuated the mortality rate and inflammatory responses during endotoxemia in rats; however, whether propofol retains its antiinflammatory effects during hypothermia has not been determined. We investigated the effects of propofol on endotoxemic rats subjected to moderate or mild hypothermia.

METHODS

Male Wistar rats (n = 88) were anesthetized intraperitoneally with pentobarbital sodium and assigned to one of two protocols: one representing moderate hypothermia (30 degrees -32 degrees C) and the other representing mild hypothermia (33 degrees -35 degrees C). Each protocol included four equal-sized groups: group A, Escherichia coli endotoxin (15 mg x kg(-1), i.v.) and normothermia; group B, propofol (10 mg x kg(-1) x h(-1), i.v.) and normothermia after endotoxin injection; group C, endotoxin (15 mg x kg(-1), i.v.) and hypothermia; and group D, propofol (10 mg x kg(-1) x h(-1), i.v.) and hypothermia after endotoxin injection. Rats then were warmed or cooled to maintain rectal temperatures as above for 6 h. The mortality rate was assessed up to 6 h after endotoxin injection. In addition, we assessed hemodynamics, acid-base status, and plasma cytokine concentrations.

RESULTS

Endotoxemic rats developed hypotension and metabolic acidosis as well as increased plasma cytokine concentrations. Mortality rates 6 h after endotoxin injection were 70%, 40%, 10%, and 0% for groups A-D, respectively, at moderate hypothermia. Propofol administration to endotoxemic rats with hypothermia, whether moderate or mild, also attenuated the high mortality rate, metabolic acidosis, and elevation of cytokines, but these effects were not superior to those of hypothermia alone.

CONCLUSION

During hypothermia, propofol administration does not have additive beneficial antiinflammatory effects.

Plasminogen activator inhibitor 1 promotes a poor prognosis in sepsis-induced disseminated intravascular coagulation

Sepsis-induced disseminated intravascular coagulation (DIC) is a serious condition because it is closely linked to the development of multiple organ dysfunctions. We compared molecular fibrinolysis markers for 117 patients with sepsis-induced DIC and 1627 patients with nonseptic DIC. Levels of fibrinogen and fibrin degradation products and D-dimer were significantly lower in sepsis-induced DIC cases than in nonseptic DIC cases. In septic DIC cases, plasma plasminogen activator inhibitor 1 (PAI-1) levels were significantly higher than in nonseptic DIC cases. D-dimer levels were negatively correlated with plasma PAI-1 levels in septic DIC cases. Multiple Organ Dysfunction Scores were significantly higher in septic DIC patients with PAI-1 levels >90 ng/mL than in the group with PAI-1 levels <30 ng/mL. The Kaplan-Meier survival functions until 28 days after DIC diagnosis were significantly lower in the group with PAI-1 levels >90 ng/mL than in the other groups. In a multivariate analysis, plasma PAI-1 levels at DIC diagnosis were an independent risk factor for mortality in sepsis-induced DIC (hazard ratio, 1.012; P = .008). These data suggest that plasma PAI-1 plays an important role in sustaining DIC in septic DIC cases and contributes to multiple organ failure and decreased survival in such patients.

Lipoteichoic acid and muramyl dipeptide synergistically induce maturation of human dendritic cells and concurrent expression of proinflammatory cytokines

Maturation is an important process by which dendritic cells (DC) develop the potent antigen-presentation capacity necessary for efficient activation of adaptive immunity. Here, we have investigated the ability of lipoteichoic acid (LTA) and muramyl dipeptide (MDP; the minimal structural unit of peptidoglycan with immunostimulating activity) to induce maturation of human immature DC (iDC), derived from peripheral blood CD14-positive cells, and the production of proinflammatory cytokines. Exposure of iDC to staphylococcal LTA (StLTA) at 1 or 10 microg/ml or MDP at 0.1 or 1 microg/ml alone had little effect on the expression of CD80 and CD83, with a minor increase in expression of CD86, all of which are indicative of cell surface markers for maturation. However, there was a synergistic expression of these molecules when iDC were stimulated with StLTA and MDP together. It is interesting that selective induction of MHC Class II expression was observed during the DC maturation, only when costimulated with LTA plus MDP, and Escherichia coli LPS induced dramatic expression of MHC Classes I and II. Endocytosis assay using Dextran-FITC showed that costimulation with StLTA and MDP attenuated the endocytic capacity of the DC, which is a typical phenomenon of DC maturation. Concomitantly, increased expression of DEC-205, but decreased expression of CD206, was observed under the same costimulating condition. Furthermore, ELISA showed that secretions of TNF-alpha and IL-12 p40, but not IL-10, were induced in iDC by the costimulation. These results suggest that StLTA and MDP synergistically induce maturation and activation of human DC.

(Peri)vascular production and action of pro-inflammatory cytokines in brain pathology

In response to tissue injury or infection, the peripheral tissue macrophage induces an inflammatory response through the release of IL-1β (interleukin-1β) and TNFα (tumour necrosis factor α). These cytokines stimulate macrophages and endothelial cells to express chemokines and adhesion molecules that attract leucocytes into the peripheral site of injury or infection. The aims of the present review are to (i) discuss the relevance of brain (peri)vascular cells and compartments to bacterial meningitis, HIV-1-associated dementia, multiple sclerosis, ischaemic and traumatic brain injury, and Alzheimer's disease, and (ii) to provide an overview of the production and action of pro-inflammatory cytokines by (peri)vascular cells in these pathologies of the CNS (central nervous system). The brain (peri)vascular compartments are highly relevant to pathologies affecting the CNS, as infections are almost exclusively blood-borne. Insults disrupt blood and energy flow to neurons, and active brain-to-blood transport mechanisms, which are the bottleneck in the clearance of unwanted molecules from the brain. Perivascular macrophages are the most reactive cell type and produce IL-1β and TNFα after infection or injury to the CNS. The main cellular target for IL-1β and TNFα produced in the brain (peri)vascular compartment is the endothelium, where these cytokines induce the expression of adhesion molecules and promote leucocyte infiltration. Whether this and other effects of IL-1 and TNF in the brain (peri)vascular compartments are detrimental or beneficial in neuropathology remains to be shown and requires a clear understanding of the role of these cytokines in both damaging and repair processes in the CNS.

Hepatoprotective effects of whey protein on D-galactosamine-induced hepatitis and liver fibrosis in rats

The hepatoprotective effects of whey protein on two injections of D-galactosamine (300 mg/kg, i.p.) were investigated in rats fed a modified AIN-93M diet formulated with a protein source of casein or whey for 16 d. The whey protein-containing diet clearly suppressed an increase in plasma alanine and aspartate aminotransferase activity, lactate dehydrogenase and bilirubin, which are hepatitis markers, and also hyaluronic acid, a fibrosis marker. In addition, it suppressed histopathological signs of portal fibrosis, bile duct proliferation, and perivenular sclerosis. These results suggest that supplementation with whey protein can help prevent the development of hepatitis and portal fibrosis.

Effects of post-treatment with direct hemoperfusion using a CTR column on mortality and inflammatory responses to endotoxin-induced shock in rats

BACKGROUND

To clarify the effects of post-treatment with direct hemoperfusion using a CTR column on the mortality and inflammatory responses to endotoxin-induced shock in rats.

METHODS

Thirty-six male rats were randomly assigned to 1 of 3 groups (n = 12/group): the endotoxemic group, receiving intravenous Escherichia coli endotoxin (15 mg/kg over 2 min); the control column group, treated without CTR for 120 min at 2 h after endotoxin injection, and CTR-post-treatment group, treated with CTR for 120 min at 2 h after endotoxin injection. Hemodynamics, arterial blood gases, and mortality were recorded for the 8-hour observation period, and plasma cytokine concentrations were measured every 4 h.

RESULTS

The mortality rates were 83, 83 and 33% for the endotoxemic, control column, and CTR post-treatment groups, respectively. The increases in IL-6 concentrations were less for the CTR post-treatment group than the other 2 groups.

CONCLUSION

The present study shows that CTR post-treatment inhibited hypotension and elevations in IL-6 concentrations, reducing the mortality rate of rats with endotoxin-induced shock.

A novel adsorbent of circulating bacterial toxins and cytokines: the effect of direct hemoperfusion with CTR column for the treatment of experimental endotoxemia

OBJECTIVES

The current study examined the ability of a new adsorbent, CTR, to remove enterotoxins, toxic shock syndrome toxin-1 (TSST-1), and cytokines from blood and/or serum in vitro and the effects of the extracorporeal treatment with CTR column on mortality rate and inflammatory responses to endotoxic shock in vivo.

DESIGN

Laboratory investigation.

SETTING

University and company experimental laboratory.

MATERIALS

CTR is composed of porous cellulose beads to which a hydrophobic organic compound with a hexadecyl alkyl chain has been covalently bound to the surface as a ligand. Human/bovine serum and human blood samples in vitro and Male Wistar rats were used.

INTERVENTIONS

CTR's ability to adsorb bacterial toxins and cytokines related to sepsis in serum and/or blood was examined with an in vitro batch adsorption protocol. In vivo, male Wistar rats were anesthetized and assigned to one of three groups (n=14 per group): Escherichia coli endotoxin (15 mg/kg intravenously) alone (endotoxemic), apheresis with control column without CTR for 120 mins (control column), or extracorporeal treatment with CTR column for 120 mins (CTR treatment).

MEASUREMENTS AND MAIN RESULTS

With use of the CTR adsorbent, the adsorption rates were 50% to 90% for enterotoxins, TSST-1, and cytokines such as TNF-alpha and interleukin (IL)-6 in the batch tests. In vivo, the mortality rates at 8 hrs after endotoxin injection were 92%, 92%, and 14% for the endotoxemic, control column, and CTR treatment groups, respectively. Hypotension and elevated plasma cytokine concentrations and the infiltration of neutrophils of the lungs were less conspicuous in the CTR treatment group than in the other two groups.

CONCLUSIONS

CTR, a novel adsorbent, effectively adsorbed small- to middle-sized proteins, such as cytokines, enterotoxins, and TSST-1 in vitro. Direct hemoperfusion apheresis with CTR column reduced mortality and had inhibitory effects on the inflammatory responses during endotoxemia in vivo. These findings suggest that extracorporeal blood purification with CTR column may be available to use for patients with sepsis and/or endotoxemia.

Effects of Extracorporeal Treatment With Lixelle on the Mortality and Inflammatory Responses to Endotoxin-Induced Shock in Rats

Endotoxemia and endotoxic shock are common problems in intensive care units and are associated with a very high mortality. Several previous studies have shown that Lixelle, which absorbs beta2-microglobulin for the treatment of dialysis-related amyloidosis, is also useful for the adsorption of inflammatory cytokines and endotoxins. The current study examined the use of Lixelle and its effects on the mortality and inflammatory responses to endotoxin-induced shock in rats. Male Sprague-Dawley rats were anesthetized and assigned to one of four groups (N = 13 per group): Escherichia coli endotoxin (15 mg/kg, i.v.) alone (endotoxemic); direct hemoperfusion apheresis without Lixelle for 120 min (direct hemoperfusion (DHP) alone); Lixelle treatment with Lixelle for 120 min immediately after endotoxin injection (Lixelle treatment); or Lixelle treatment with Lixelle for 120 min 2 h after endotoxin injection (Lixelle post-treatment). Hemodynamics and plasma lactate and cytokine concentrations were measured during observation. Mortality was assessed up to 8 h after the endotoxin injection. The mortality rates at 8 h after endotoxin injection were 92%, 85%, 23% and 46% for the endotoxemic, DHP-alone, Lixelle treatment, and Lixelle post-treatment groups, respectively. Elevated plasma cytokine concentrations were less conspicuous in the Lixelle treatment group than in the other three groups. Thus, Lixelle treatment drastically reduced the high mortality and the inflammatory responses in endotoxin-exposed rats. Moreover, Lixelle post-treatment also suppressed hypotension and a high mortality, although the inflammatory responses were the same as for endotoxin alone. These findings indicate that Lixelle treatment might be an effective therapy for endotoxemia and endotoxic shock.

Liver inflammation and regeneration: two distinct biological phenomena or parallel pathophysiologic processes?

The anatomic localization and unique vasculature of the liver, along with its cell properties, make this organ an efficient line of defense against blood-borne infections, either systemic or arising in the abdomen. Liver cells can modify the host immune response by releasing immunomodulatory molecules, interacting with cells of the immune system and acting as scavengers for inflammatory mediators. However, these defensive functions do not protect the liver itself from the severe injury that may be caused by pathogens, toxins or pollutant xenobiotics. Therefore, the mammalian liver has developed a unique adaptation in the form of an astonishing regenerative capability. The complexity of regeneration requires a well-orchestrated system to control this process. Growing evidence suggest the importance of immune mechanisms as a part of this system. It seems likely that the mechanisms that serve to eliminate infections (and may simultaneously cause liver injury) are also active in restoring the structural and functional integrity of the damaged liver.

Sevoflurane pretreatment inhibits endotoxin-induced shock in rats

We examined the effects of sevoflurane pretreatment on mortality and inflammatory responses during endotoxin-induced shock. Rats were allocated randomly to 1 of 4 groups (n = 12 per group): an endotoxemia group, receiving IV Escherichia coli endotoxin (15 mg/kg over 2 min); a saline control group, receiving 0.9% saline (1.0 mL/kg); a sevoflurane-only group, receiving 2.4% sevoflurane for 30 min immediately before injection of 0.9% saline; and a sevoflurane pretreatment group, receiving 2.4% sevoflurane for 30 min immediately before injection of endotoxin. Hemodynamic variables, arterial blood gases, and plasma concentrations of tumor necrosis factor-alpha and interleukin-6 were measured. The 8-h mortality rate was determined. Systolic arterial blood pressure and acid-base balance improved with sevoflurane pretreatment before induction of endotoxemia. Mortality rates 8 h after endotoxin injection were 83%, 8%, 0%, and 25% for the endotoxemia, saline control, sevoflurane-only, and sevoflurane pretreatment groups, respectively. Plasma cytokine concentrations were significantly larger in the endotoxemia group than in the other groups. Sevoflurane pretreatment inhibited inflammatory responses and decreased mortality in rats exposed to endotoxin.

IMPLICATIONS

Sevoflurane pretreatment decreased mortality rate, severity of hypotension, and acidosis, and inhibited cytokine responses in rats injected with endotoxin, suggesting that sevoflurane may be an anesthetic of choice in endotoxemic states.

Recognition of Staphylococcus aureus by the innate immune system

The gram-positive bacterium Staphylococcus aureus is a major pathogen responsible for a variety of diseases ranging from minor skin infections to life-threatening conditions such as sepsis. Cell wall-associated and secreted proteins (e.g., protein A, hemolysins, and phenol-soluble modulin) and cell wall components (e.g., peptidoglycan and alanylated lipoteichoic acid) have been shown to be inflammatory, and these staphylococcal components may contribute to sepsis. On the host side, many host factors have been implicated in the innate detection of staphylococcal components. One class of pattern recognition molecules, Toll-like receptor 2, has been shown to function as the transmembrane component involved in the detection of staphylococcal lipoteichoic acid and phenol-soluble modulin and is involved in the synthesis of inflammatory cytokines by monocytes/macrophages in response to these components. Nod2 (nucleotide-binding oligomerization domain 2) is the intracellular sensor for muramyl dipeptide, the minimal bioactive structure of peptidoglycan, and it may contribute to the innate immune defense against S. aureus. The staphylococcal virulence factor protein A was recently shown to interact directly with tumor necrosis factor receptor 1 in airway epithelium and to reproduce the effects of tumor necrosis factor alpha. Finally, peptidoglycan recognition protein L is an amidase that inactivates the proinflammatory activities of peptidoglycan. However, peptidoglycan recognition protein L probably plays a minor role in the innate immune response to S. aureus. Thus, several innate immunity receptors may be implicated in host defense against S. aureus.

Prevention and treatment of multiple organ dysfunction syndrome: lessons learned and future prospects

Gram-negative bacteria commonly cause serious infections in hospitalized patients, and those that lead to bacteremic episodes and sepsis syndrome are associated with the highest mortality rate. Sepsis syndrome frequently progresses to multisystem organ dysfunction and failure, with as many as 400,000 cases occurring annually. Unfortunately, the associated mortality rate remains about 40%. Lipopolysaccharide (LPS, endotoxin), an integral component of the gram-negative bacterial outer membrane, plays a critical role in the pathophysiology of this lethal disease process. It is capable of interacting with host macrophages, a process that leads to the secretion of an increasingly well-characterized array of macrophage cytokines. Several different classes of compounds that bind directly to LPS and thereby neutralize its effects are being examined. These consist of anti-LPS monoclonal antibodies (mAbs), naturally occurring proteins and their derivatives (e.g., bactericidal/permeability-increasing protein [BPI], Limulus anti-LPS factor [LALF]), and certain antibiotics (polymyxin B, taurolidine). The molecular biology of BPI, LALF, and LPS binding protein (LBP, which augments the host response to LPS) is of considerable interest, as each demonstrates considerable genetic sequence homology. Although two anti-LPS monoclonal antibodies (HA-1A, E5) did not demonstrate efficacy during sepsis syndrome, information obtained from these clinical trials provided investigators with the ability to better understand this disease process. However, a detailed understanding of the biology of endotoxin antagonism is beginning to emerge, and the application of this knowledge in the clinical setting provides hope that it may be possible to reduce the mortality of sepsis syndrome caused by these microorganisms to a statistic well below the current 40%.

Agents protecting against sepsis from the roots of Angelica dahurica

In the course of isolating agents preventing sepsis from the EtOAc extract of the roots of Angelica dahurica, four known furanocoumarins, isoimperatorin (1), oxypeucedanin (2), (+/-)-byakangelicin (3), and (+)-oxypeucedanin hydrate (4), were isolated as active compounds based on the in vivo assay model of sepsis induced by lipopolysaccharide (LPS) and D-galactosamine (D-GalN). Among them, 3 showed the highest survival rate (100% with a dose of 30 mg/kg versus 20% for the control experiment) and decreased the plasma levels of tumor necrosis factor-alpha and alanine aminotransferase in mice adminstered LPS/D-GalN.

Influence of ceftriaxone treatment on FDG uptake--an in vivo [18F]-fluorodeoxyglucose imaging study in soft tissue infections in rats

Our aim was to determine the influence of antibiotic treatment using ceftriaxone on [18F]-fluorodeoxyglucose (FDG) uptake in experimental soft tissue infections. PET scans were performed in two groups (treated n=4; non-treated n=4) at days 3, 5, and 6 after inoculation of the infection. Additional autoradiography was performed in four animals at day 7 and in three animals at day 11. The difference of FDG uptake on day 5 (after three days of antibiotic treatment) between both groups proved to be significant (df=6; T=2.52; p=0.045). FDG uptake determined at the other days did not reveal significant difference between the two groups. It seems to be possible that the effect of antibiotic treatment on FDG uptake is less evident than reported for therapy monitoring of cancer treatment. The change of FDG uptake over time in treated and untreated infections is complex and further in vivo experiments have to be initiated to investigate the potential value of clinical FDG PET in therapy monitoring of infection.

Protective constituents against sepsis in mice from the root cortex of Paeonia suffruticosa

The bioassay-guided fractionation of protective agents against sepsis-induced lethality from the root cortex of Paeonia suffruticosa ANDREWS (Ranunculaceae) led to the isolation of eight known compounds: paeonol (1), 2,5-dihydroxy-4-methoxyacetophenone (2), acetovanillone (3), paeonoside (4), paeoniflorin (5), oxypaeoniflorin (6), apiopaeonoside (7), and methyl 3-hydroxy-4-methoxybenzoate (8). Among them, 3 showed the highest survival rate (100% with a dose of 30 mg/kg versus 17% for the control experiment) and reduced alanine aminotransferase level to be a half of the control value on the sepsis model induced by lipopolysaccharide/D-galactosamine.

Therapeutic potential of targeting IL-1 and IL-18 in inflammation

Interleukin (IL)-1 and IL-18 are cytokines that play a major role in autoimmune and inflammatory human disease. Both cytokines drive a wide range of pro-inflammatory effector networks in many cell types and use common signal transduction cascades. IL-1, IL-18 and other members of the IL-1 superfamily are expressed at elevated levels in tissue and fluid samples isolated from patients with many chronic inflammatory diseases. These cytokines are primary drivers in acute and chronic animal models of inflammation and their blockade has been shown to ameliorate disease in preclinical studies. Biological agents that target IL-1 have demonstrated efficacy in patients with rheumatoid arthritis, and further agents targeting IL-1 or IL-18 neutralisation are in clinical development. The potential for such agents spans human disease where tissue destruction is a primary end point of cytokine action.

Different staphylococcal strains elicit different levels of production of T-helper 1-inducing cytokines

Cytokine production has been implicated in the pathogenic mechanisms of infections caused by the staphylococci, since these bacteria may act as strong cytokine inducers. To gain deeper insight into the Th1 immune response activated by these bacteria, we have analyzed the interferon (IFN), interleukin-12 (IL-12) and IL-18-inducing activities of different Staphylococcus aureus (S. aureus), S. epidermidis and S. saprophyticus strains in human monocytes and murine bone marrow macrophages. A large majority of the S. aureus strains elicited the simultaneous production of IL-12 p70 and IFN-alpha in the human monocytes, while the S. epidermidis and S. saprophyticus strains induced only a low level of production, if any, of these cytokines. Furthermore, a majority of the S. aureus strains induced significantly higher IL-12 p70 and IL-18 titers in the murine bone marrow macrophages than did the S. epidermidis and S. saprophyticus strains. As IL-12, IL-18 and IFN-alpha stimulate Th1 differentiation synergistically, we suggest that S. aureus strains bias the immune response toward a Th1 phenotype, whereas S. epidermidis and S. saprophyticus strains provide a weaker stimulus for the production of Th1-inducing cytokines, and accordingly possibly elicit a less extensive Th1-associated adaptive immunity.

High-density lipoproteins in sepsis and septic shock: metabolism, actions, and therapeutic applications

Sepsis and septic shock are important causes of morbidity and lethality in noncoronary intensive care units. Circulating levels of high-density lipoproteins (HDLs) are reduced in sepsis/septic shock, and the magnitude of this reduction is positively correlated with the severity of the illness. The mechanisms underlying this phenomenon are incompletely understood, although increased levels of several acute-phase proteins, including serum amyloid A (SAA) and secretory phospholipase A2 (sPLA2), may contribute to the decrease in plasma HDLs. It has been suggested that HDLs possess anti-inflammatory properties and, hence, may play a crucial role in innate immunity by regulating the inflammatory response as well as being capable of reducing the severity of organ injury in animals and patients with septic shock. These protective effects of HDLs are mediated mainly via (a) lipopolysaccharide (LPS) binding and neutralization, (b) the HDL-associated enzymes, plasma paraoxonase (PON1) and platelet-activating factor acetylhydrolase (PAF-AH), which protect low-density lipoproteins against peroxidative damage, (c) inhibition of the expression of endothelial cell adhesion molecules and release of proinflammatory cytokines, which prevents inflammatory cell infiltration and subsequent multiple organ dysfunction, and (d) stimulation of the expression of endothelial nitric oxide synthase (eNOS). Thus, HDL exerts potent anti-inflammatory effects, some of which are independent of endotoxin binding and might be useful in the treatment of patients with not only sepsis/septic shock but also other conditions associated with an uncontrolled inflammatory response, such as ischemia-reperfusion injury and hemorrhagic shock.

Effects of dexmedetomidine on mortality rate and inflammatory responses to endotoxin-induced shock in rats

OBJECTIVES

The aim of this study was to document the effects of a new sedative agent, dexmedetomidine, on the mortality rate and inflammatory responses to endotoxin-induced shock in rats.

DESIGN

Randomized laboratory study.

SETTING

University experimental laboratory.

SUBJECTS

Fifty-seven male rats.

INTERVENTIONS

The animals were randomly assigned to one of four groups. The endotoxemic group (n = 16) received intravenous Escherichia coli endotoxin (15 mg/kg over 2 mins). The saline control group (n = 10) was given saline alone. The dexmedetomidine alone group (n = 15) was treated identically to the control group but also received dexmedetomidine (infusion at 5 microg.kg(-1).hr(-1)) immediately after the injection of 0.9% saline. The dexmedetomidine-endotoxin group (n = 16) was treated identically to the endotoxemic group with the additional administration of dexmedetomidine (infusion at 5 microg.kg(-1).hr(-1)) immediately after endotoxin injection.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and arterial blood gases were recorded and plasma cytokine concentrations measured during the observation. The mortality rate was assessed up to 8 hrs after endotoxin or saline injection. In addition, microscopic findings of lung tissue for each group were obtained at necropsy. Mortality rates 8 hrs after endotoxin injection were 94%, 10%, 0%, and 44% for the endotoxemic, saline control, dexmedetomidine alone, and dexmedetomidine-endotoxin groups, respectively. Hypotension and increases in plasma cytokine (tumor necrosis factor-alpha and interleukin-6) concentrations and infiltration of neutrophils in the airspace or vessel walls of the lungs were less in the dexmedetomidine-endotoxin group than in the endotoxemic group.

CONCLUSIONS

Dexmedetomidine reduced mortality rate and had an inhibitory effect on inflammatory response during endotoxemia. These findings suggest that dexmedetomidine administration may inhibit the inflammatory response.