Burns, bacterial translocation, gut barrier function, and failure

Toll-like receptor-4 mediates intestinal barrier breakdown after thermal injury

OBJECTIVE

Toll-like receptor 4 (TLR-4) activation after sterile injury leads to organ dysfunction at distant sites. We have shown previously that intestinal barrier breakdown and alteration of tight junction proteins follows thermal injury; however, the role of TLR-4 in this process remains unclear. We hypothesized that increased intestinal permeability and barrier breakdown after burns is a TLR-4 dependent process; hence, knocking down the TLR-4 gene would have a protective effect on burn-induced intestinal dysfunction.

METHODS

Male C57BL/6J (TLR-4 wild type [WT]) and C57BL/10ScN (TLR-4 knockout [KO]) mice were assigned randomly to either 30% total body surface area steam burn or sham injury. At 4 h, permeability to intraluminally administered fluorescein isothiocyanate (FITC)-dextran was assessed by measuring the fluorescence of the serum. Intestinal samples were analyzed for the presence of the tight junction protein occludin by immunoblotting and immunohistochemistry. Tumor necrosis factor (TNF)-alpha concentrations in the serum and intestines were measured by enzyme-linked immunosorbent assay at 2 h post-burn.

RESULTS

Serum concentrations of FITC-dextran were decreased in TLR-4 KO mice compared with TLR-4 WT mice after burn injury (92.0 micrograms/mL and 264.5 micrograms/mL, respectively; p < 0.05). After injury, no difference in intestinal permeability was observed between the TLR-4 KO mice and the TLR-4 WT sham-treated mice. The TLR-4 KO mice had preservation of occludin concentrations after thermal injury in both immunoblot and immunohistochemistry assays, but concentrations were decreased in TLR-4 WT animals. The serum concentrations of TNF-alpha serum were higher in TLR-4 WT burned animals than in the sham-treated mice. The TLR-4 KO animals had unmeasurable concentrations of TNF-alpha. No differences in TNF-alpha were observed in the intestinal tissue at 2 h.

CONCLUSIONS

Mice with TLR-4 KO have less intestinal permeability to FITC-dextran than do TLR-4 WT mice after burn injury as a result of alterations in the tight junction protein occludin. These findings suggest that the greater intestinal permeability and barrier breakdown after burn injury is a TLR-4-dependent process. Toll-like receptor 4 may provide a useful target for the prevention and treatment of systemic inflammatory response syndrome and multisystem organ failure after injury.

Commensal microflora induce host defense and decrease bacterial translocation in burn mice through toll-like receptor 4

Background

Major burn is associated with decreased gut barrier function and increased bacterial translocation (BT). This study is to investigate whether commensal microflora induce host defense and decrease BT in burn mice.

Methods

First, we treated Wild type (WT) mice with antibiotics in drinking water for 4 weeks to deplete gut commensal microflora. At week 3, drinking water was supplemented with lipopolysaccharide (LPS); a ligand for TLR4, to trigger TLRs in gut. The intestinal permeability, glutathione level, NF-κB DNA-binding activity, TLR4 expression of intestinal mucosa, BT to mesenteric lymph nodes (MLNs), and bacterial killing activity of peritoneal cells were measured after thermal injury. Second, lung of animals were harvested for MPO activity and TNFα mRNA expression assay. Third, WT animals were treated with oral antibiotics with or without LPS supplement after burn. At 48 hr after burn, TLR4 expression of intestinal mucosa and bacterial killing activity of cells were examined. Finally, bacterial killing activity and BT to MLNs after thermal injury in C3H/HeJ (TLR4 mutant) mice were measured.

Results

Burn induced BT to MLNs in WT mice. Commensal depletion decreased TLR4 expression as well as NF-κB activation of intestine, myeloperoxidase (MPO) activity as well as TNFα expression of lung, and bacterial killing activity of peritoneal cells. Oral LPS supplement markedly reduced 81% of burn-induced BT and increased TLR4 expression, MPO activity of lung, as well as bacterial killing activity of peritoneal cells. LPS supplement did not change BT or bacterial killing activity in C3H/HeJ mice.

Conclusions

Collectively, commensal microflora induce TLR4 expression of intestine and bacterial killing activity of inflammatory cells in burn. TLR4 ligand increases bacterial killing activity and decreases burn-induced BT. Taken together with the abolition of LPS effect in TLR4 mutant mice, we conclude that commensal microflora induce host defense and decrease bacterial translocation in burn mice through toll-like receptor 4.

Septicemia secondary to ileus in trauma patients: a human model for bacterial translocation

Paralytic ileus is a common problem in trauma patients. We present two cases of ileus leading to septicemia. Both patients developed sudden septicemia on hospital day six and underwent urgent exploratory laparotomies, and both were found to only have paralytic ileus without evidence of bowel injury or obstruction. We attribute the cause of septicemia to bacterial translocation secondary to ileus.

Use of plasma procalcitonin levels as an adjunct to clinical microbiology

Procalcitonin (PCT) is synthesized by a large number of tissues and organs in response to invasion by pathogenic bacteria, fungi, and some parasites. Current PCT assays are rapid, specific, and of sufficient sensitivity to detect increases in PCT serum levels within 4 to 6 h of initiation of infection. Clinically, PCT levels may help in decisions regarding the need for empirical antibiotic therapy, "source control" of infection, and duration of antibiotic therapy. The addition of PCT levels to bacterial culture and viral detection results can assist with the separation of colonization and invasion by pathogenic bacteria.

Procalcitonin as a marker of severe bacterial infection in children in the emergency department

Procalcitonin, the prohormone of calcitonin, is a relatively new and innovative marker of bacterial infection that has multiple potential applications in the pediatric emergency department. In healthy individuals, circulating levels of procalcitonin are generally very low (<0.05 ng/mL), but in the setting of severe bacterial infection and sepsis, levels can increase by hundreds to thousands of fold within 4 to 6 hours. Although the exact physiologic function of procalcitonin has not been determined, the consistent response and rapid rise of this protein in the setting of severe bacterial infection make procalcitonin a very useful biomarker for invasive bacterial disease. In Europe, serum procalcitonin measurements are frequently used in the diagnosis and the management of patients in a variety of clinical settings. To date, the use of procalcitonin has been limited in the United States, but this valuable biomarker has many potential applications in both the pediatric emergency department and the intensive care unit. The intent of this article is to review the history of procalcitonin, describe the kinetics of the molecule in response to bacterial infection, describe the laboratory methods available for measuring procalcitonin, examine the main causes of procalcitonin elevation, and evaluate the potential applications of procalcitonin measurements in pediatric patients.

Incidence and bacteriology of burn infections at a military burn center

Considerable advancements in shock resuscitation and wound management have extended the survival of burned patients, increasing the risk of serious infection. We performed a 6-year review of bacteria identification and antibiotic susceptibility records at the US Army Institute of Surgical Research Burn Center between January 2003 and December 2008. The primary goal was to identify the bacteria recovered from patients with severe burns and determine how the bacteriology changes during extended hospitalization as influenced by population and burn severity. A total of 460 patients were admitted to the burn ICU with 3507 bacteria recovered from 13,727 bacteriology cultures performed. The most prevalent organisms recovered were Acinetobacter baumannii (780), Pseudomonas aeruginosa (703), Klebsiella pneumoniae (695) and Staphylococcus aureus (469). A. baumannii was most often recovered from combat-injured (58%) and S. aureus the most frequent isolate from local (46%) burn patients. Culture recovery rate of A. baumannii and S. aureus was highest during the first 15 hospital days (73% and 71%); while a majority of P. aeruginosa and K. pneumoniae were recovered after day 15 (63% and 53%). All 4 pathogens were recovered throughout the course of hospitalization. A. baumannii was the most prevalent pathogen recovered from patients with total body surface area (TBSA) burns less than 30% (203) and 30-60% (338) while P. aeruginosa was most prevalent in patients with burns greater than 60% TBSA (292). Shifting epidemiology of bacteria recovered during extended hospitalization, bacteriology differences between combat-injured and local burn patients, and impact of % TBSA may affect patient management decisions during the course of therapy.

Burn teams and burn centers: the importance of a comprehensive team approach to burn care

Remarkable advances in burn care have been made over recent decades, and it is recognized that the organized efforts of burn teams are required to continue enhancing survival rates and quality of life for patients. Patients with major burns are unique, representing one of the most severe models of trauma, and therefore necessitate treatment in the best specialized facilities available for that endeavor. Burn centers have developed to meet these intricate needs but can only function most productively and efficiently through well-organized, multifaceted, patient-centered teams in the areas of both clinical care and research.

Early enteral nutrition, provided within 24 h of injury or intensive care unit admission, significantly reduces mortality in critically ill patients: a meta-analysis of randomised controlled trials

PURPOSE

To determine whether the provision of early standard enteral nutrition (EN) confers treatment benefits to critically ill patients.

METHODS

Medline and EMBASE were searched. Hand citation review of retrieved guidelines and systematic reviews were undertaken, and academic and industry experts were contacted. Methodologically sound randomised controlled trials (RCTs) conducted in critically ill patient populations that compared the delivery of standard EN, provided within 24 h of intensive care unit (ICU) admission or injury, to standard care were included. The primary analysis was conducted on clinically meaningful patient-oriented outcomes. Secondary analyses considered vomiting/regurgitation, pneumonia, bacteraemia, sepsis and multiple organ dysfunction syndrome. Meta-analyses were conducted using the odds ratio (OR) metric and a fixed effects model. The impact of heterogeneity was assessed using the I (2) metric.

RESULTS

Six RCTs with 234 participants were analysed. The provision of early EN was associated with a significant reduction in mortality [OR = 0.34, 95% confidence interval (CI) 0.14-0.85] and pneumonia (OR = 0.31, 95% CI 0.12-0.78). There were no other significant differences in outcomes. A sensitivity analysis and a simulation exercise confirmed the presence of a mortality reduction.

CONCLUSION

Although the detection of a statistically significant reduction in mortality is promising, overall trial quality was low, trial size was small, and the findings may be restricted to the patient groups enrolled into included trials. The results of this meta-analysis should be confirmed by the conduct of a large multi-centre trial enrolling diverse critically ill patient groups.

[Immunology and sepsis syndrome in burn trauma]

Despite significant advances in burn surgery and critical care, severe burn trauma defined as injuries covering more than 25% of the total body surface area, is still associated with high mortality and morbidity. Burn trauma is a whole body injury where peripheral dermal injury rapidly results in systemic inflammation and inflammatory core organ damage. The severe disturbance of internal homeostasis involves all vital organ systems and obligates early referral to specialized burn centers. Treatment of severely burned patients is a multifaceted challenge directed by pathophysiologic events which progress from local skin destruction, disruption of physicochemical and microvascular barriers to breakdown of peripheral and central circulation, organ failure and ultimately death. While early intensive care focuses on maintenance of tissue oxygenation and perfusion, surgical treatment deals with management of the burn wounds as a source of inflammation and infection. Here wound debridement and coverage is essential to abrogate systemic effects of inflammation and limit pathogen invasion. While control of early burn stages minimizes mortality due to burn shock, subsequent burn sepsis continues to be a formidable challenge for physicians and the main cause of burn mortality.

Orexigenic hormone ghrelin ameliorates gut barrier dysfunction in sepsis in rats

OBJECTIVES

We have recently shown that ghrelin, a novel orexigenic hormone, is reduced in sepsis. Ghrelin treatment, mediated through ghrelin receptors in the brain, attenuates sepsis-induced inflammation and mortality. Gut barrier dysfunction is common in sepsis. High-mobility group B1 (HMGB1) increases gut permeability both in vitro and in vivo. However, it remains unknown whether ghrelin has any effects on HMGB1 and gut barrier function in sepsis. We hypothesized that ghrelin decreases HMGB1 release and attenuates sepsis-induced gut barrier dysfunction through central ghrelin receptors.

DESIGN

Prospective, controlled, and randomized animal study.

SETTING

A research institute laboratory.

SUBJECTS

Male adult Sprague-Dawley rats (275-325 g).

INTERVENTIONS

Cecal ligation and puncture (CLP) followed by injection/infusion of ghrelin.

MEASUREMENTS AND MAIN RESULTS

Five hours after CLP, a bolus intravenous injection of 2 nmol of ghrelin was followed by a continuous infusion of 12 nmol of ghrelin via an osmotic mini-pump for 15 hrs. Twenty hours after CLP, brain ghrelin levels, serum HMGB1 levels, ileal mucosal permeability to fluorescein isothiocyanate dextran, bacterial counts in the mesenteric lymph nodes complex, and gut water content were determined. In additional groups of animals, bilateral trunk vagotomy was performed at 5 hrs after CLP before ghrelin injection. Furthermore, to confirm the role of central ghrelin receptors in ghrelin's effect, ghrelin (1 nmol) was administered through intracerebroventricular injection at 5 hrs after CLP. Our results showed that brain levels of ghrelin decreased by 34% at 20 hrs after CLP. Intravenous administration of ghrelin completely restored brain levels of ghrelin, significantly reduced the elevated HMGB1 levels, and attenuated gut barrier dysfunction. Vagotomy eliminated ghrelin's inhibition of HMGB1 and attenuation of gut barrier dysfunction. Intracerebroventricular injection of ghrelin decreased serum HMGB1 levels and ameliorated gut barrier dysfunction.

CONCLUSIONS

Ghrelin reduces serum HMGB1 levels and ameliorates gut barrier dysfunction in sepsis by vagus nerve activation via central ghrelin receptors. Ghrelin can be further developed as a novel agent to protect gut barrier function in sepsis.

Effect of vagus nerve stimulation on thermal injury in rats

OBJECTIVE

To investigate the effects of vagus nerve stimulation on haemodynamics, pulmonary histopathology, arterial blood gas and pro-inflammatory responses to thermal injury.

INTERVENTIONS

Forty-eight male Sprague-Dawley (SD) rats were randomly divided into six equal groups: normal control (NC) group; thermal injury (TEM) group subjected to 40% total body surface area (%TBSA) third-degree thermal injury; vagotomy (VGX) group subjected to bilateral cervical vagotomy after thermal injury; electrical stimulation (STM) group subjected to bilateral cervical vagotomy plus the left vagus nerve trunk electrical stimulation (5 V, 2 ms and 1 Hz) after thermal injury; the antagonist of muscarinic acetylcholine receptor (MRA) group administrated with atropine (0.1 mg kg(-1)) before electrical stimulation and the antagonist of nicotinic acetylcholine receptor (NRA) group administrated with hexamethonium (10 mg kg(-1)) before electrical stimulation.

MEASUREMENTS AND MAIN RESULTS

The haemodynamics, histopathology of lung tissue, arterial blood gas, lactic acid, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) levels were measured. Vagus nerve electrical stimulation not only significantly increased the mean arterial pressure (MAP) and heart rate (HR), but also decreased the infiltration of inflammatory cells into interstitial and alveolar spaces after thermal challenge and attenuated TNF-alpha and IL-6 production. Hexamethonium pre-treatment significantly reversed the effects of vagal electrical stimulation, but atropine administration before electrical stimulation had no such effects.

CONCLUSIONS

Direct electrical stimulation of the vagus nerve might produce therapeutic effect on thermal injury. The effect may be realised by limiting the inflammatory response via nicotinic acetylcholine receptors in rats.

Somatostatin limits intestinal ischemia-reperfusion injury in macaques via suppression of TLR4-NF-kappaB cytokine pathway

OBJECTIVE

Intestinal ischemia-reperfusion (IIR)-induced gut injury remains a challenge for critically ill patients despite the oxidative stress theory that has been elaborated. This study aimed to test whether Toll-like receptor 4 (TLR4) is involved in gut injury during IIR and whether somatostatin (SST) affects TLR4-nuclear factor-kappaB (NF-kappaB) cytokine pathway in the intestinal mucosa of macaques.

DESIGN

Fifteen macaques were randomized into control, IIR, and SST + IIR groups. Pieces of isolated ileal epithelium from each animal were incubated with lipopolysaccharide (LPS), interferon-gamma, or SST. Expression of TLR4 and NF-kappaBp65 was evaluated by immunohistochemical staining, Western blot analysis and reverse transcription polymerase chain reaction. Cytokine levels were measured by ELISA. Radioimmunoassay was used to determine of SST levels.

MEASUREMENTS AND MAIN RESULTS

Significant overexpression (IIR vs control) of ileal TLR4 (0.17 +/- 0.03 vs 0.05 +/- 0.02), NF-kappaBp65 (0.55 +/- 0.11 vs 0.15 +/- 0.05), and TNF-alpha (213.2 +/- 29.2 vs 56.0 +/- 10.04) after IIR was greatly decreased (p < 0.05) by prophylactic use of SST (TLR4: 0.06 +/- 0.02; NF-kappaBp65: 0.26 +/- 0.09; TNF-alpha: 97.1 +/- 32.3) in vivo. TLR4 expression in the ileal epithelium treated with LPS and SST (1,330 +/- 93) was significantly lower than that in the ileal epithelium treated with LPS alone (2,088 +/- 126) in vitro. SST levels in plasma (3.67 +/- 0.41 ng/ml) and ileal mucosa (1,402.3 +/- 160 ng/mg protein) of the IIR group were significantly lower than those (6.09 +/- 1.29 ng/ml, 2,234. 8 +/- 301.8 ng/mg protein) in the control group (p < 0.05).

CONCLUSIONS

Endogenous SST is a crucial inhibitor of massive inflammatory injury in the intestinal mucosa via direct suppression of the TLR4-NF-kappaB cytokine pathway induced by LPS in ileal epithelium. IIR attacks caused shortages of endogenous SST in the plasma and intestinal mucosa of macaques in this study. Therefore, preventive supplements of SST may limit intestinal injury of macaques by IIR.

TLR ligand decreases mesenteric ischemia and reperfusion injury-induced gut damage through TNF-alpha signaling

Ischemic gut contributes to the development of sepsis and organ failure in critically ill patients. Toll-like receptors (TLRs) have been reported to mediate the pathophysiology of organ damage following ischemia/reperfusion (I/R) injury. We hypothesize that LPS, a ligand for TLR4, decreases mesenteric I/R injury-induced gut damage through tumor necrosis factor alpha (TNF-alpha) signaling. First, wild-type (WT) mice were fed with oral antibiotics for 4 weeks to deplete the intestinal commensal microflora. At week 3, drinking water was supplemented with LPS (10 microg/microL) to trigger TLRs. The intestinal mucosa was harvested for TLR4 protein, caspase 3 activity, and terminal deoxynucleotide transferase labeling assay. Second, WT and Tnfrsf1a mice received 30-min ischemia and 30-min reperfusion (30I-30R) or 30I-180R of the intestine; intestinal permeability and lipid peroxidation of the intestine were examined. Third, WT and Tnfrsf1a mice were fed with oral antibiotics with or without LPS and received 30I-180R of the intestine. The intestinal mucosa was harvested for lipid peroxidation; glutathione (GSH) level; nuclear factor kappaB (NF-kappaB) and AP-1 DNA-binding activity; Bcl-w, TNF-alpha, and CXCR2 mRNA expression; and HSP70 protein assay. Commensal depletion increased caspase 3 activity as well as villi apoptosis and decreased TLR4 expression of the intestinal mucosa. LPS increased TLR4 expression and decreased villi apoptosis. Commensal depletion augmented 30I-180R-induced intestine permeability as well as lipid peroxidation and decreased GSH level in WT mice but not in Tnfrsf1a mice. LPS decreased 30I-180R-induced intestinal permeability as well as lipid peroxidation and increased GSH level of the intestinal mucosa in WT mice but not in Tnfrsf1a mice. Commensal depletion with 30I-180R increased NF-kappaB and AP-1 DNA-binding activity, HSP70 protein expression, and decreased Bcl-w and TNF-alpha mRNA expression of the intestinal mucosa in WT mice but not in Tnfrsf1a mice. Collectively, commensal microflora induces TLR4 expression and decreases apoptosis of the intestinal mucosa. Commensal depletion enhances I/R-induced gut damage. LPS prevents I/R-induced intestinal permeability, lipid peroxidation, and decrease in GSH level. Given that the preventive effect of LPS on I/R-induced gut damage and NF-kappaB activity of the intestine is abolished in Tnfrsf1a mice, we conclude that TLR ligand decreases mesenteric I/R injury-induced gut damage through TNF-alpha signaling.

Fasting exacerbates and feeding diminishes LPS-induced liver injury in the rat

INTRODUCTION

Enteral nutrition improves clinical outcomes. The effects of feeding on LPS induced liver injury are unknown. We hypothesized that feeding would attenuate liver injury from LPS.

METHODS

Fasted or fed rats were given LPS (20 mg/kg i.p.) or saline for 5 h and sacrificed. Serum aminotransferases and cytokines (immunoassay) were measured. Oxidative stress protein (iNOS, COX2, and HO1) assessments (Western immunoblot) were also obtained.

RESULTS

In fasted rats, LPS significantly increased serum aminotransferase levels, enhanced hepatic COX2, iNOS, and HO1 immunoreactivity, and increased serum cytokine levels when compared to controls. While feeding diminished liver enzymes, attenuated expression of COX2 and iNOS, and blunted production of pro-inflammatory cytokines, it did not modulate LPS-induced expression of the anti-inflammatory markers HO1 and IL-10.

CONCLUSION

These data suggest that feeding decreases liver injury by attenuating expression of pro-inflammatory mediators while maintaining expression of anti-inflammatory mediators, both systemically and locally.

Causes of mortality by autopsy findings of combat casualties and civilian patients admitted to a burn unit

BACKGROUND

Approximately 5% of combat-related injuries include burns. Previous studies have shown similar mortality rates between military and civilian burn casualties; but causes of death were not detailed.

STUDY DESIGN

We retrospectively reviewed autopsy reports of patients with burns treated at the US Army Institute of Surgical Research Burn Center from 2004 to 2007.

RESULTS

Of 1,255 admissions, 100 (8%) died, with autopsies performed on 74 (36 burned during military operations). Causes of death included infection (61%); disorders of the pulmonary (55%), cardiac (36%), renal (27%), gastrointestinal (27%), and central nervous (11%) systems; and multiorgan dysfunction (15%). Patients burned as a result of military operations were younger men with more associated inhalation injuries, greater severity of injury, and longer time from injury to admission and to death. They died more frequently of infection (notably fungus, Pseudomonas, and Klebsiella) and gastrointestinal complications; and those not burned in military operations had greater numbers of cardiac and renal causes of death.

CONCLUSION

Casualties of military operations are clinically different and die from different causes than patients not burned during military operations. The differences are likely reflective of a younger population, with greater severity of illness and longer times from injury to admission. Therapeutic interventions should focus on prevention of infection and gastrointestinal catastrophes in military burn casualties, which are similar to younger burn patients in the US, and minimizing cardiac complications in civilian burn casualties, who are typically older patients and possibly reflective of patients with more comorbidities.

Metabolism in rats during antiorthostatic hypokinesia

O2 consumption and CO2 release in 3 groups of awake rats were studied on a MM-100 metabolic monitor system (CWE Inc.). The animals of 2 groups were preadapted to 4-h maintenance in special boxes (2 weeks). The rats could perform rotational movements and limited movements in the rostrocaudal direction (hypokinesia). The animals of one group were daily exposed to 4-h antiorthostatic load (<or=45 degrees) for 2 weeks. After 2 weeks, the intensity of metabolism in rats with antiorthostatic hypokinesia was lower than in hypokinetic specimens (by 15-20%, p<0.05) and freely moving animals (by 20-25%, p<0.05). Interleukin-6 concentration in rats with antiorthostatic hypokinesia (0.25+/-0.09 pg/ml) was lower than in hypokinetic (4.01+/-0.57 pg/ml) and freely moving animals (3.69+/-0.56 pg/ml). The decrease in the concentration of a proinflammatory cytokine interleukin-6 during experimental antiorthostatic hypokinesia reflects inhibition of metabolic processes, which are activated during antiorthostatism (but not hypokinesia).

Effect of honey on bacterial translocation and intestinal morphology in obstructive jaundice

AIM: To evaluate the effects of honey on bacterial translocation and intestinal villus histopathology in experimental obstructive jaundice.

METHODS: Thirty Wistar-Albino rats were randomly divided into three groups each including 10 animals: group I, sham-operated; group II, ligation and section of the common bile duct (BDL); group III, bile duct ligation followed by oral supplementation of honey (BDL + honey) 10 g/kg per day. Liver, blood, spleen, mesenteric lymph nodes, and ileal samples were taken for microbiological, light and transmission electrone microscopic examination.

RESULTS: Although the number of villi per centimeter and the height of the mucosa were higher in sham group, there was no statistically significant difference between sham and BDL + honey groups (P > 0.05). On the other hand, there was a statistically significant difference between BDL group and other groups (P < 0.05). The electron microscopic changes were also different between these groups. Sham and honey groups had similar incidence of bacterial translocation (P > 0.05). BDL group had significantly higher rates of bacterial translocation as compared with sham and honey groups. Bacterial translocation was predominantly detected in mesenteric lymph nodes.

CONCLUSION: Supplementation of honey in presence of obstructive jaundice ameliorates bacterial translocation and improves ileal morphology.

Procalcitonin assay in systemic inflammation, infection, and sepsis: clinical utility and limitations

OBJECTIVE

The use of procalcitonin (ProCT) as a marker of several clinical conditions, in particular, systemic inflammation, infection, and sepsis, will be clarified, and its current limitations will be delineated. In particular, the need for a more sensitive assay will be emphasized. For these purposes, the medical literature comprising clinical studies pertaining to the measurement of serum ProCT in various clinical settings was examined.

DATA SOURCE AND SELECTION

A PubMed search (1965 through November 2007) was conducted, including manual cross-referencing. Pertinent complete publications were obtained using the MeSH terms procalcitonin, C-reactive protein, sepsis, and biological markers. Textbook chapters were also read and extracted.

DATA EXTRACTION AND SYNTHESIS

Available clinical and other patient data from these sources were reviewed, including any data relating to precipitating factors, clinical findings, associated illnesses, and patient outcome. Published data concerning sensitivity, specificity, and reproducibility of ProCT assays were reviewed.

CONCLUSIONS

Based on available data, the measurement of serum ProCT has definite utility as a marker of severe systemic inflammation, infection, and sepsis. However, publications concerning its diagnostic and prognostic utility are contradictory. In addition, patient characteristics and clinical settings vary markedly, and the data have been difficult to interpret and often extrapolated inappropriately to clinical usage. Furthermore, attempts at meta-analyses are greatly compromised by the divergent circumstances of reported studies and by the sparsity and different timing of the ProCT assays. Although a high ProCT commonly occurs in infection, it is also elevated in some noninfectious conditions. Thus, the test is not a specific indicator of either infection or sepsis. Moreover, in any individual patient, the precipitating cause of an illness, the clinical milieu, and complicating conditions may render tenuous any reliable estimations of severity or prognosis. It also is apparent that even a febrile septic patient with documented bacteremia may not necessarily have a serum ProCT that is elevated above the limit of functional sensitivity of the assay. In this regard, the most commonly applied assay (i.e., LUMItest) is insufficiently sensitive to detect potentially important mild elevations or trends. Clinical studies with a more sensitive ProCT assay that is capable of rapid and practicable day-to-day monitoring are needed and shortly may be available. In addition, investigations showing that ProCT and its related peptides may have mediator relevance point to the need for evaluating therapeutic countermeasures and studying the pathophysiologic effect of hyperprocalcitonemia in serious infection and sepsis.

Hydrophobicity of mucosal surface and its relationship to gut barrier function

Loss of the gut barrier has been implicated in the pathogenesis of the multiple organ dysfunction syndrome, and, thus, understanding the intestinal barrier is of potential clinical importance. An important, but relatively neglected, component of the gut barrier is the unstirred mucus layer, which through its hydrophobic and other properties serves as an important barrier to bacterial and other factors within the gut lumen. Thus, the goal of this study was to establish a reproducible method of measuring mucosal hydrophobicity and test the hypothesis that conditions that decrease mucosal hydrophobicity are associated with increased gut permeability. Hydrophobicity was measured in various segments of normal gut by measuring the contact angle of an aqueous droplet placed on the mucosal surface using a commercial goniometer. Second, the effect of the mucolytic agent N-acetyl cysteine on mucosal hydrophobicity and gut permeability was measured, as was the effects of increasing periods of in vivo gut ischemia on these parameters. Gut ischemia was induced by superior mesenteric artery occlusion, and gut permeability was measured by the mucosal-to-serosal passage of fluoresceine isothiocyanate-dextran (4.3 kDa) (FD4) across the everted sacs of ileum. Intestinal mucosal hydrophobicity showed a gradual increase from the duodenum to the end of the ileum and remained at high level in the cecum, colon, and rectum. Both N-acetyl cysteine treatment and ischemia caused a dose-dependent decrease in mucosal hydrophobicity, which significantly correlated increased gut permeability. Mucosal hydrophobicity of the intestine can be reproducibly measured, and decreases in mucosal hydrophobicity closely correlate with increased gut permeability. These results suggest that mucosal hydrophobicity can be a reliable method of measuring the barrier function of the unstirred mucus layer and a useful parameter in evaluating the pathogenesis of gut barrier dysfunction.

Toll-like receptor 4 contributes to microvascular inflammation and barrier dysfunction in thermal injury

Systemic and microvascular inflammation plays a key role in the development of multiple organ failure after infection, sepsis, and traumatic injury. Toll-like receptors (TLRs) regulate host responses to pathogens and sterile, injury-associated inflammatory responses. We investigated whether TLR-4 contributes to microvascular dysfunction during thermal injury in vivo in anesthetized wild-type or TLR-4 (-/-) mice receiving either a 25% total body surface area full-thickness scald burn or sham treatment on the dorsal skin. Using intravital microscopy, we assessed the hemodynamics and leukocyte dynamics in the mesenteric microvasculature as representative of the splanchnic microcirculation at a site remote from the burn wound. The transvascular flux of fluorescein isothiocyanate-albumin across mesenteric venules was measured as an indicator of microvascular permeability. Furthermore, cultured microvascular endothelial cell models were used to evaluate the endothelial-specific mechanisms involved in TLR-4-mediated barrier dysfunction. The results showed significantly elevated microvascular permeability in wild-type mice after burn, whereas this response was markedly attenuated in TLR-4 (-/-) mice. Burn injury also increased leukocyte adhesion in mesenteric venules of wild-type mice, and a blunted leukocyte response was seen in the TLR-4 mice. Treatment of endothelial cell monolayers with burn plasma induced a rapid reduction in the transendothelial electrical resistance measured by electric cell-substrate impedance sensing, indicative of endothelial cell-cell adhesive barrier dysfunction. Reducing expression of TLR-4 with siRNA treatment attenuated this response. Taken together, these data indicate that TLR-4 plays an important role in microvascular leakage and leukocyte adhesion under the inflammatory condition associated with nonseptic thermal injury.

Protective effect of Fab' in immunoglobulin Y against lipopolysaccharide on intestinal mucosa during the early stage in severely burned gut-derived endotoxemia mice

AIM: To investigate the protective effect of Fab' against endotoxin on intestinal mucosa during the early stage in severely burned gut-derived endotoxemia mice, and to explore a new method for preventing and curing burn sepsis.

METHODS: The severely burned gut-derived endotoxemia mice model was used, and the mice were divided into 3 groups: control group (group A), burn group (group B) and Fab' treatment group (group C). At the 6^th, 12^th, 24^th and 48th h after burn injury, the levels of serum tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-10 (IL-10) were determined by enzyme-linked immunosorbent assay. Intestinal tissues were collected for pathological examination.

RESULTS: In comparison with those in group A, the levels of serum TNF-α, IL-1β and IL-10 in group B increased significantly and reached the peak 24 h after burn injury (TNF-α: 242.06 ± 3.93 ng/L vs 14.98 ± 1.13 ng/L; IL-1β: 37.86 ± 5.88 ng/L vs 14.39 ± 2.43 ng/L; IL-10: 324.78 ± 65.82 ng/L vs 97.63 ± 20.48 ng/L; all P < 0.01). The levels of TNF-α, IL-1β and IL-10 at 6, 12, 24 and 48 h in group C (6 h: 99.69 ± 10.67, 19.19 ± 1.17, 160.44 ± 24.99 ng/L; 12 h: 172.07 ± 22.47, 22.29 ± 3.32, 185.44 ± 22.30 ng/L; 24 h: 125.98 ± 6.93, 28.39 ± 2.59, 237.11 ± 30.28 ng/L; 48 h: 107.88 ± 5.24, 26.23 ± 2.51, 207.86 ± 20.35 ng/L) were significantly different from those in group B (all P < 0.05). Pathological examination showed a lower degree of intestinal mucosal injury in group C than in compared with group B.

CONCLUSION: The Fab' against endotoxin can significantly decrease the level of serum TNF-α, IL-1β and IL-10 during the early stage in severely burned gut-derived endotoxemia mice, and consequently alleviate the endotoxin-induced injury.

Organ-specific inflammation following acute ethanol and burn injury

Clinical and experimental evidence demonstrates that ethanol exposure prior to injury alters local and systemic inflammatory responses, increasing morbidity and mortality. Moreover, the aberrant inflammatory responses can directly and indirectly lead to the poor prognosis after injury by altering leukocyte infiltration into the wound site and remote organs and by suppressing immunity leading to increased susceptibility to opportunistic infections. Recent studies from our laboratory have focused on inflammatory responses at the wound site and in other distal organs after exposure to acute ethanol and burn injury. This combined insult leads to increased mortality after dermal or intratracheal pseudomonas infection, relative to infected mice given ethanol or burn injury alone. The increased mortality in mice given ethanol and burn injury parallels elevated serum levels of proinflammatory cytokines, IL-6 and TNF-alpha, marked infiltration of leukocytes into the lung and gut, as well as immunosuppression at the sites of infection. Bacterial translocation from the gut is likely to be responsible, in part, for the aberrant accumulation of leukocytes in the lungs of ethanol-exposed, burn-injured mice. Additionally, other factors, such as expression of adhesion molecules, increased chemokine production, and leakiness of the vascular endothelium, may also be involved.

Intestinal alkaline phosphatase is a gut mucosal defense factor maintained by enteral nutrition

Under conditions of starvation and disease, the gut barrier becomes impaired, and trophic feeding to prevent gut mucosal atrophy has become a standard treatment of critically ill patients. However, the mechanisms responsible for the beneficial effects of enteral nutrition have remained a mystery. Using in vitro and in vivo models, we demonstrate that the brush-border enzyme, intestinal alkaline phosphatase (IAP), has the ability to detoxify lipopolysaccharide and prevent bacterial invasion across the gut mucosal barrier. IAP expression and function are lost with starvation and maintained by enteral feeding. It is likely that the IAP silencing that occurs during starvation is a key component of the gut mucosal barrier dysfunction seen in critically ill patients.

Mesenteric lymph duct ligation attenuates lung injury and neutrophil activation after intraperitoneal injection of endotoxin in rats

BACKGROUND

The release of injurious factors into the mesenteric lymph from the ischemic intestine has been shown to contribute to lung injury and systemic inflammation after shock and trauma. Since endotoxemia is also associated with gut injury, we tested the hypothesis that mesenteric lymph contributes to the lung injury seen in endotoxemia and that the ligation of the mesenteric lymph duct will attenuate this injury.

METHODS

To test this hypothesis, male Sprague-Dawley rats were given intraperitoneal injections (i.p.) of lipopolysaccharide (LPS) (10 mg/kg) with or without mesenteric lymph duct ligation (LDL). At 6 hours after injection of LPS, gut and lung injury, lung permeability, and neutrophil CD11b expression were measured. Lung permeability was quantified by calculating the percentage of Evan's Blue dye and the total protein concentration in the bronchoalveolar lavage fluid (BALF) when compared with the plasma and gut and lung injury were assessed morphologically.

RESULTS

LDL attenuated LPS- induced lung injury, lung permeability, and rat PMN CD11b expression but not villous injury. The magnitude of lung permeability as measured by Evan's Blue was approximately twofold greater in the LPS rats when compared with the LPS-treated rats with LDL. The expression of CD11b was greater in the LPS rats when compared with LPS rats with LDL or to sham controls (582 +/- 106 vs. 364 +/- 29 vs. 224 +/- 12 mean fluorescence intensity p < 0.001).

CONCLUSION

Based on the attenuation of lung injury and CD11b expression, these results suggest that LPS-induced lung injury and neutrophil activation is partially mediated through the release of factors from the injured gut into mesenteric lymph.

Acute ethanol exposure combined with burn injury enhances IL-6 levels in the murine ileum

BACKGROUND

Recent studies suggest that ethanol use imposes a greater risk of trauma-associated intestinal injury than trauma alone. The initiating and regulatory factors for multiple organ dysfunction syndromes are not well defined, yet evidence points to the gut as a possible trigger of the systemic inflammatory cascade as well as a potential source of cytokines. In the current study, we hypothesized that ethanol administration would alter cytokine levels and intestinal infiltration by neutrophils within the ileum of mice exposed to burn injury (15% total body surface of dorsal skin).

METHODS

Ileal samples were collected for histological assessment, myeloperoxidase quantitation and the protein presence of tumor necrosis factor alpha (TNFalpha), interleukin (IL-) 6, macrophage inflammatory protein-2 (MIP-2; CXCL2) and the anti-inflammatory cytokine, IL-10. Additional ileal tissue samples were examined for localization of the IL-6 immunoreactivity.

RESULTS

We did not detect statistically significant cytokine/chemokine differences (MIP-2 and IL-10) between sham control and treatment conditions at either 2 or 24 hours. However, there was a significant decrease in TNFalpha at 24 hours in both burn injury alone and in combination with ethanol treatment conditions (p < 0.05). In addition, there was an increase in IL-6 levels at 24 hours in intestinal tissue obtained from mice subjected to a combination of acute ethanol and burn injury, compared to the mice receiving burn or sham injury (p < 0.001). Ileal homogenate increases in IL-6 at 24 hours were concurrent with decreased villus height in the ileum, but no discernable changes in neutrophil infiltration (myeloperoxidase activity levels) at either 2 or 24 hours. Additional immunocytochemical localization studies of ileal tissue revealed that there was a substantial increase of IL-6 in intestinal enterocytes subjected to both burn injury alone, or in combination with acute ethanol exposure.

CONCLUSIONS

The present study suggests that acute ethanol exposure combined with burn injury enhances levels of IL-6 protein in the ileum. The enhanced levels of ileal IL-6 are likely due to enterocyte production of the cytokine.

Bactericidal/permeability increasing protein attenuates the myocardial inflammation/dysfunction that occurs with burn complicated by subsequent infection

Intubation and mechanical ventilation after burn contribute to pneumonia-related infection. Although postburn presence or absence of endotoxin has been described, inactivation of Toll-like receptor 4 signaling has been shown to improve postburn organ function, suggesting that LPS participates in burn-related susceptibility to infection. We hypothesized that bactericidal/permeability-increasing protein (rBPI) given postburn would attenuate myocardial inflammation/dysfunction associated with postburn septic challenge given 7 days postburn. Rats were given burn over 40% total body surface area, lactated Ringer 4 ml.kg(-1).% burn(-1); burns received either vehicle or rBPI, 1 mg.kg(-1).h(-1) for 48 h postburn. Postburn day 7, subgroups of burns and shams were given intratracheal Klebsiella pneumoniae, 4 x 10(6) CFU to produce burn complicated by sepsis; additional sham and burn subgroups received intratracheal vehicle to produce sham sepsis. Vehicle-treated groups: 1) sham burn + sham sepsis 2) sham burn + sepsis, 3) burn + sham sepsis, 4) burn + sepsis. rBPI-treated groups: 5) sham burn + sham sepsis, 6) sham burn + sepsis, 7) burn + sham sepsis, 8) burn + sepsis. Cardiomyocyte cytokine secretion and myocardial function were studied 24 h after septic challenge, postburn day 8. Pneumonia-related infection 8 days after vehicle-treated burn produced myocyte cytokine secretion (pg/ml), indicated by increased myocyte TNF-alpha, 549 +/- 46; IL-1beta, 50 +/- 8; IL-6, 286 +/- 3 levels compared with levels in sham myocytes (TNF-alpha, 88 +/- 11; IL-1beta, 7 +/- 1; IL-6, 74 +/- 10; P < 0.05). Contractile dysfunction was evident from lower left ventricular pressure +/-dP/dt values in this group compared with sham. rBPI attenuated myocyte cytokine responses to septic challenge and improved contractile function, suggesting that burn-related mobilization of microbial-like products contribute to postburn susceptibility to infection.

Making sense of multiple organ dysfunction syndrome

Despite recent advances in critical care medicine, caring for patients with MODS remains one of the most challenging experience a critical care can encounter. New therapies that current exist and continue to be developed contribute to successful outcomes for patients with MODS, but there is no substitute for prevention and early intervention for persons at risk for developing MODS. Early and subtle changes in the patient who is at risk and has endured an initial insult can make a great difference in the patient's outcome and chances of mortality. Goal-directed therapy, supportive management, as well as an understanding of the inflammatory process are key to decreasing the mortality rate among patients with MODS.

Candida glabrata colonizes but does not often disseminate from the mouse caecum

Candida glabrata is the second or third most frequent cause of candidaemia. The gastrointestinal tract is considered to be a major portal of entry for systemic candidiasis, but relatively few studies have investigated the pathogenesis of C. glabrata. Experiments were designed to clarify the ability of C. glabrata to disseminate from the mouse intestinal tract. Following oral inoculation, C. glabrata readily colonized the caeca [approx. 107 cells (g caecum)−1] of antibiotic-treated mice, but extraintestinal dissemination was not detected. Superimposing several mouse models of trauma and/or immunosuppression known to induce dissemination of Candida albicans and other intestinal microbes did not cause C. glabrata to disseminate often, although one exception was mice given high doses of dexamethasone for 4 days. These data support the hypothesis that the antibiotic-treated mouse intestine may be an epidemiological reservoir for C. glabrata and that this yeast tends to disseminate under specific clinical conditions.

Acute alcohol intoxication increases interleukin-18-mediated neutrophil infiltration and lung inflammation following burn injury in rats

In this study, we examined whether IL-18 plays a role in lung inflammation following alcohol (EtOH) and burn injury. Male rats (∼250 g) were gavaged with EtOH to achieve a blood EtOH level of ∼100 mg/dl before burn or sham injury (∼12.5% total body surface area). Immediately after injury, rats were treated with vehicle, caspase-1 inhibitor AC-YVAD-CHO to block IL-18 production or with IL-18 neutralizing anti-IL-18 antibodies. In another group, rats were treated with anti-neutrophil antiserum ∼16 h before injury to deplete neutrophils. On day 1 after injury, lung tissue IL-18, neutrophil chemokines (CINC-1/CINC-3), ICAM-1, neutrophil infiltration, MPO activity, and water content (i.e., edema) were significantly increased in rats receiving a combined insult of EtOH and burn injury compared with rats receiving either EtOH intoxication or burn injury alone. Treatment of rats with caspase-1 inhibitor prevented the increase in lung tissue IL-18, CINC-1, CINC-3, ICAM-1, MPO activity, and edema following EtOH and burn injury. The increase in lung IL-18, MPO, and edema was also prevented in rats treated with anti-IL-18 antibodies. Furthermore, administration of anti-neutrophil antiserum also attenuated the increase in lung MPO activity and edema, but did not prevent the increase in IL-18 levels following EtOH and burn injury. These findings suggest that acute EtOH intoxication before burn injury upregulates IL-18, which in turn contributes to increased neutrophil infiltration. Furthermore, the presence of neutrophils appears to be critical for IL-18-meditaed increased lung tissue edema following a combined insult of EtOH and burn injury.

Review article: bacterial translocation in the critically ill--evidence and methods of prevention

BACKGROUND

Delayed sepsis, systemic inflammatory response syndrome (SIRS) and multiorgan failure remain major causes of morbidity and mortality on intensive care units. One factor thought to be important in the aetiology of SIRS is failure of the intestinal barrier resulting in bacterial translocation and subsequent sepsis.

AIM

This review summarizes the current knowledge about bacterial translocation and methods to prevent it.

METHODS

Relevant studies during 1966-2006 were identified from a literature search. Factors, which detrimentally affect intestinal barrier function, are discussed, as are methods that may attenuate bacterial translocation in the critically ill patient.

RESULTS

Methodological problems in confirming bacterial translocation have restricted investigations to patients undergoing laparotomy. There are only limited data available relating to specific interventions that might preserve intestinal barrier function or limit bacterial translocation in the intensive care setting. These can be categorized broadly into pre-epithelial, epithelial and post-epithelial interventions.

CONCLUSIONS

A better understanding of factors that influence translocation could result in the implementation of interventions which contribute to improved patient outcomes. Glutamine supplementation, targeted nutritional intervention, maintaining splanchnic flow, the judicious use of antibiotics and directed selective gut decontamination regimens hold some promise of limiting bacterial translocation. Further research is required.

Neonatal gut barrier and multiple organ failure: role of endotoxin and proinflammatory cytokines in sepsis and necrotizing enterocolitis

BACKGROUND/PURPOSE

Failure of the gut barrier and endotoxemia have been implicated in sepsis and multiple organ failure (MOF) syndromes in adults. The contributions of endotoxin (ETX) and proinflammatory cytokines (CKs) to the pathophysiology of disease and the outcomes of infants in the neonatal intensive care unit (NICU) are not clear. We measured ETX and CK concentrations in infants who presented with clinical signs of sepsis and/or necrotizing enterocolitis (NEC) to study their impact on MOF and outcomes.

METHODS

Blood samples from infants with signs of NEC and/or sepsis were collected for culture and determination of complete blood cell counts and concentrations of CKs (interleukin [IL]-1beta, tumor necrosis factor [TNF] alpha, and IL-6) and ETX at the onset of illness. Infants with signs of sepsis but without those of NEC were classified by blood culture results into a confirmed sepsis group (ie, positive culture) or a control group (ie, negative culture). Endotoxin concentrations were determined by chromogenic Limulus amebocyte lysate assay, and CK levels were quantitated by enzyme-linked immunoassay. Data are expressed as mean +/- SD and as odds ratios (ORs) with 95% confidence intervals (CIs). P values lower than .05 were considered to be significant.

RESULTS

There was no demographic or clinical difference among the NEC (n = 27), sepsis (n = 44), and control (n = 56) groups, except that fewer (P = .02) infants in the NEC group (11%) had received maternal milk feedings as compared with infants in the sepsis group (23%) and those in the control group (39%). Endotoxin concentrations were higher (P < .0001) in the NEC group (3.30 +/- 2.11) as compared with the sepsis group (0.67 +/- .86) and the control group (0.09 +/- 0.24). Generalized linear regression analysis using formula feeding, mechanical ventilation, and gram-negative bacteremia as covariates demonstrated that NEC increased ETX concentrations independently (r = .80; P < .0001). Endotoxemia correlated with higher concentrations of all 3 CKs (P < .0001). There was an inverse association between ETX and both platelet count (r = -0.30; P = .0003) and absolute neutrophil count (r = -0.29; P = .0009). Infants who died of MOF had higher concentrations of ETX (2.83 +/- 3.04 vs 0.67 +/- 1.04 EU/mL; P < .0001), IL-1beta (509 +/- 493 vs 106 +/- 223 pg/mL; P < .0001), IL-6 (416 +/- 308 vs 99 +/- 165 pg/mL; P < .0001), and TNF-alpha (503 +/- 449 vs 126 +/- 237 pg/mL; P < .0001) as compared with those without MOF. Eighty-six percent of the infants with MOF died. Multivariate logistic regression analysis demonstrated that higher ETX concentrations (OR = 2.47; 95% CI = 1.39-4.40; P = .002) and lower gestational age (OR = 1.41; 95% CI = 1.12-1.77; P = .003) predicted mortality.

CONCLUSIONS

Neonatal endotoxemia and release of proinflammatory CKs are important contributors to MOF and mortality in the NICU. Endotoxemia was most severe at the onset of illness among the infants with NEC, suggesting that gut barrier failure plays an important role in adverse outcomes in the NICU.

Practical guidelines for nutritional management of burn injury and recovery

Nutrition practice in burn injury requires a multifaceted approach aimed at providing metabolic support during a heightened inflammatory state, while accommodating surgical and medical needs of the patient. Nutritional assessment and determination of nutrient requirements is challenging, particularly given the metabolic disarray that frequently accompanies inflammation. Nutritional therapy requires careful decision making, regarding the safe use of enteral or parenteral nutrition and the aggressiveness of nutrient delivery given the severity of the patient's illness and response to treatment. With the discovery that specific nutrients can actually alter the course of disease, the role of nutrition support in critical illness has shifted from one of preventing malnutrition to one of disease modulation. Today the use of glutamine, arginine, essential fatty acids, and other nutritional factors for their effects on immunity and cell regulation is becoming more common, although the evidence is often lagging. An exciting dichotomy exits, forcing nutrition support specialists to make responsible choices while remaining open to new potential helpful therapeutic options.

Effects of various enteral nutrition solutions on bacterial translocation and intestinal morphology during the postoperative period

Bacterial translocation is the passage of bacteria or endotoxins from the gastrointestinal tract to extraintestinal sites, such as mesenteric lymph nodes, liver, spleen, and bloodstream. In this study, the investigators examined the effects of various enteral nutrients on bacterial translocation and intestinal morphology during the postoperative period. Sixty rats were randomly divided into 5 groups, each of which included 12 animals; cecal mobilization was performed in all groups. Group I rats were fed rat chow and water; group II was given standard enteral nutrients; group III, high-energy enteral nutrients; group IV, enteral nutrients supplemented with fiber; and group V, immunonutrients. Bacterial translocation was detected in mesenteric lymph nodes, spleen, liver, and blood cultures. Changes in the terminal ileum were scored from 0 to 4 with the morphologic scoring system. Bacterial translocation was predominantly detected in mesenteric lymph nodes. Rats fed immunonutrients (group V) showed a significant reduction in bacterial translocation compared with other groups. Although minor morphologic alterations in the villi were observed in groups IV and V, the histologic scores of these groups were not statistically different from the scores of control group members. In the present study, investigators evaluated the effects of various enteral nutritional solutions on bacterial translocation and intestinal morphology during the postoperative period. Enteral diets supplemented with arginine, nucleotides, and omega-3 fatty acids were found to reduce bacterial translocation. The investigators concluded that this effect might be related to improvement in immune function resulting from the use of immunonutrients.

“Systemic apoptotic response” after thermal burns

The systemic pathophysiologic changes following thermal injuries affect multiple organs and body systems leading to clinical manifestations including shock, intestinal alterations, respiratory and renal failure, immunosuppression and others. Recent advances in the comprehension of mechanisms underlying systemic complications of thermal injuries have contributed to uncover part of the cellular and molecular basis that underlie such changes. Recently, programmed cell death (apoptosis) has been considered playing an important role in the development of such pathological events. Therefore, investigators utilizing animal models and clinical studies involving human primates have produced a large body of information suggesting that apoptosis is associated with most of the tissue damages triggered by severe thermal injuries. In order to draw the attention on the important role of apoptosis on systemic complications of thermal injuries, in this review we describe most of these studies, discuss possible cellular and molecular mechanisms and indicate ways to utilize them for the development of therapeutic strategies by which apoptosis may be prevented or counteracted.

Protective roles of hydroxyethyl starch 130/0.4 in intestinal inflammatory response and survival in rats challenged with polymicrobial sepsis

BACKGROUND

The gut is considered an important target organ of injury after severe insult such as sepsis, trauma and shock. Hydroxyethyl starch (HES) 130/0.4 has been developed to improve the pharmacokinetics of current medium molecular weight HES solutions. We investigated the protective effects of HES 130/0.4 on intestinal inflammatory response and survival in a rat polymicrobial sepsis model induced by cecal ligation and puncture.

METHODS

Animals were treated with HES 130/0.4 or saline at 4, 10, 16 or 22 h after the induction of sepsis or sham-operation and were sacrificed 2 h after resuscitation. Intestines were harvested for measurement of tumour necrosis factor alpha (TNF-alpha), interleukin (IL)-10 and macrophage inflammatory protein-2 (MIP-2) production by EELISA; intercellular adhesion molecule-1 (ICAM-1) mRNA expression by reverse-transcription PCR; nuclear factor-kappa B (NF-kappaB) by electrophoretic mobility shift assay; neutrophil sequestration by myeloperoxidase (MPO) assay; intestinal permeability by fluorescein isothiocyanate-labeled dextran assay. In addition, the role of HES 130/0.4 in rat survival was observed.

RESULTS

Intestinal permeability was significantly decreased after HES 130/0.4 administration in septic rats, which was associated with a reduction in inflammatory mediators and NF-kappaB activation. Furthermore, early administration of HES 130/0.4 after septic insult resulted in greater decrease in inflammatory mediators. In addition, HES 130/0.4 co-administrated with antibiotics not HES 130/0.4 alone greatly improved the survival of septic rats.

CONCLUSIONS

HES 130/0.4 reduced intestinal permeability by modulating inflammatory response and had a promising effect on survival together with antibiotics under septic conditions.

The role of nuclear factor-kappa B in bacterial translocation in cholestatic rats

Xanthinoxidase (XO) derived radical species are involved in bacterial translocation (BT) in cholestatic rats. The mechanism by which XO influences remains unclear. It has been shown recently that nuclear factor-kappa B (NF-kappaB), a ubiquitous transcription factor, can be activated by oxidative stress and thereby promote the process of BT. We investigated the effects of NF-kappaB inactivation on the incidence of BT in cholestatic rats. Sprague-Dawley rats were randomly assigned to one of eight groups: groups 1-4 were sham laparotomized rats either untreated (S1) or treated for 5 days with thalidomide (S2), curcumin (S3), or Inchin-ko (ICK; S4); groups 5-8 underwent common bile duct ligation (CBDL) for 5 days and were either untreated (C1) or treated with thalidomide (C2), curcumin (C3), or ICK (C4). After 5 days bacteriological cultures were performed from portal blood and V. cava, from the central mesenteric lymph node complex (MLN), spleen, and liver. The intensity of the activated NF-kappaB-subunit p65/p50 in the ileum mucosa was estimated by light microscopy and a scoring system from 1 to 20. Malondialdehyde (MDA) and myeloperoxidase activity (MPO) in the ileum were evaluated and expressed as U/g dry weight. Thalidomide and ICK reduced in CBDL-rats significantly the BT rate (63% vs. 18%, 63% vs. 30%, P<0.01). Enzyme estimations (MDA, MPO, and GSH) in sham operated animals showed no significant changes in the untreated groups compared with the treated groups. CBDL-rats pre-treatment with all three compounds caused a significant increase of MDA levels if groups were compared with the untreated C1-group (C1 31.6+/-7.7, C2 54.5+/-12.2, C3 53.3+/-11.2, and C4 47.2+/-9.4). GSH was reduced after the pre-treatment by all compounds but only significantly after curcumin pre-treatment (C1 vs. C3: 13.9+/-1.8 vs. 7.1+/-1.8; P<0.05). MPO estimations were significantly higher in the untreated C1-group if compared with groups C2, C3, and C4 (C1 1036.4+/-340.9, C2 709.9+/-125.9, C3 545.2+/-136.6, and C4 556.7+/-247.4; P<0.05). Thalidomide inhibited significantly the activation of NF-kappaB (C2 vs. C1: 6.0+/-4.5 vs. 12.7+/-5.3; P<0.01). Likewise, Curcumin and ICK suppressed NF-kappaB activation, but this did not reach significance in this experiment. NF-kappaB is involved in the process of BT in cholestatic rats and may be activated by XO derived ROS. We assume that the activated NF-kappaB initiates transcription of target genes inducing cytokine production, which in turn disrupts the tight junctions leading to BT from the intestinal lumen to the MLNs and circulation.

Differential effect of imipenem treatment on wild-type and NK cell-deficient CD8 knockout mice during acute intra-abdominal injury

CD8 knockout mice depleted of natural killer (NK) cells by treatment with anti-asialoGM1 (CD8KO/alphaAsGM1 mice) are resistant to injury caused by cecal ligation and puncture (CLP). However, CLP-induced injury is complex. Potential sources of injury include bacterial dissemination, cecal ischemia, and translocation of bacterial toxins. We treated wild-type and CD8KO/alphaAsGM1 mice with imipenem after CLP to decrease bacterial dissemination. Additional mice were subjected to cecal ligation without puncture of the cecal wall or cecal ligation and removal of cecal contents. Imipenem treatment decreased bacterial counts by at least two orders of magnitude. However, all wild-type mice, whether treated with saline or imipenem, died by 42 h after CLP and exhibited significant hypothermia, metabolic acidosis, and high plasma cytokine concentrations. Wild-type mice subjected to cecal ligation without puncture also died, despite very low bacterial counts in blood, but wild-type mice subjected to cecal ligation and washout of cecal contents survived. In CD8KO/alphaAsGM1 mice subjected to CLP, imipenem treatment increased survival from 50% to 100%. After cecal ligation without puncture, long-term survival was 80-90% in CD8KO/alphaAsGM1 mice. Hypothermia, metabolic acidosis, and cytokine production were attenuated in CD8KO/alphaAsGM1 mice compared with wild-type controls. These results indicate that bacterial dissemination is not a major source of injury in wild-type mice after CLP, but the presence of gut flora in the cecal lumen is required for induction of systemic inflammation after cecal injury. CD8KO/alphaAsGM1 mice are resistant to the systemic manifestations of cecal injury.