Macrophage elimination increases bacterial translocation and gut-origin septicemia but attenuates symptoms and mortality rate in a model of systemic inflammation

Biomolecules Triggering Altered Food Intake during Pathogenic Challenge in Chicks

Food intake is regulated by several complicated synergistic mechanisms that are affected by a variety of internal and external influences. Some of these factors include those that are released from pathogens such as bacteria, fungi, and viruses, and most of these factors are associated with suppression of the chick's food intake. Although chicks are well-known to decrease their food intake when they experience a pathogenic challenge, the mechanisms that mediate this type of satiety are poorly understood. One of the goals of our research group has been to better understand these mechanisms in chicks. We recently provided evidence that pathogen-associated molecular patterns, which are recognized by pattern-recognition receptors such as Toll-like receptors, likely contribute to satiety in chicks that are experiencing a pathogenic challenge. Additionally, we identified several inflammatory cytokines, including interleukin-1β, tumor necrosis factor-like cytokine 1A, prostaglandins, and nitric oxide, that likely contribute to satiety during a pathogenic challenge. This review summarizes the current knowledge on pathogen-induced satiety in chicks mainly accumulated through our recent research. The research will give good information to improve the loss of production during infection in poultry production in the future.

The LipoxinA4 receptor agonist BML-111 ameliorates intestinal disruption following acute pancreatitis through the Nrf2-regulated antioxidant pathway

Acute pancreatitis (AP) is characterized by excessive release of pro-inflammatory cytokines and provokes multiorgan dysfunction. Disruption of the intestinal epithelium often occurs during and following acute pancreatitis and may aggravate systemic organ injuries. Although it has been widely investigated, to date, there is no satisfactory clinical therapy to restore the inflammatory damage. BML-111 is an endogenous lipid mediator that is analogous to LipoxinA4. It has been shown that BML-111 has a stable and potent anti-inflammatory ability. However, it is unclear whether BML-111 is involved in the process of relieving acute pancreatitis and its induced intestinal barrier damage, and the underlying mechanism of this effect. Here, we demonstrated that BML-111 could enhance the expression of E-cadherin, alleviate apoptosis, and mitigate the accumulation of reactive oxygen species in intestinal epithelial cells, thereby contributing to the anti-inflammatory efficacy in vitro and in vivo. Mechanistically, BML-111 upregulates the expression of Nrf2, which is a key regulator of the antioxidant response, and activates its downstream HO-1/NQO-1 pathway to protect against oxidative stress-induced cell death and tissue injury, consequently ameliorating pancreatitis and intestinal epithelium injury. In Nrf2-deficient cell and Nrf2-knockout mouse models, the depletion of Nrf2 blocked BML-111-induced antioxidant effects and thus was unable to exert protective effects in tissue. Taken together, BML-111 attenuated AP-related intestinal injury via an Nrf2-dependent antioxidant mechanism. Targeting this pathway is a potential therapeutic approach for AP-related intestinal injury.

Behavioral and physiological responses to intraperitoneal injection of zymosan in chicks

Zymosan is a cell wall component of the yeast Saccharomyces cerevisiae and produces severe inflammatory responses in mammals. When zymosan is peripherally injected in mammals, it induces several behavioral and physiological changes including anorexia and hyperthermia. However, to our knowledge, behavioral and physiological responses to zymosan have not yet been clarified in birds. Therefore, the purpose of the present study was to determine if intraperitoneal injection of zymosan affects food intake, voluntary activity, cloacal temperature, plasma corticosterone (CORT) and glucose concentrations, and splenic gene expression of cytokines in chicks (Gallus gallus). Intraperitoneal injection of zymosan (2.5 mg) significantly decreased food intake, voluntary activity, and plasma glucose concentration, and increased plasma CORT concentration. The injection of 0.5 mg zymosan significantly increased cloacal temperature, while 2.5 mg zymosan had a tendency to increase it. Finally, 2.5 mg zymosan significantly increased the splenic gene expression of interleukin-1β (IL-1β), IL-6, IL-8, interferon-γ, and tumor necrosis factor-like cytokine 1A. The present results suggest that zymosan would be one of components which induces nonspecific symptoms including anorexia, hypoactivity, hyperthermia, and stress responses, under fungus infection in chicks.

Pathogen clearance and immune adherence "revisited": Immuno-regulatory roles for CRIg

Rapid elimination of microbes from the bloodstream, along with the ability to mount an adaptive immune response, are essential for optimal host-defense. Kupffer cells are strategically positioned in the liver sinusoids and efficiently capture circulating microbes from the hepatic artery and portal vein, thus preventing bacterial dissemination. In vivo and in vitro studies have probed how complement receptor of the immunoglobulin superfamily (CRIg), also referred to as Z39Ig and V-set and Ig domain-containing 4 (VSIG4), acts as a critical player in pathogen recognition and clearance. While recent data suggested that CRIg may bind bacterial cell wall components directly, the single transmembrane receptor is best known for its interaction with complement C3 opsonization products on the microbial surface. On Kupffer cells, CRIg must capture opsonized microbes against the shear forces of the blood flow. In vivo work reveals how immune adherence (IA), a process in which blood platelets or erythrocytes associate with circulating bacteria, plays a critical role in regulating pathogen capture by CRIg under flow conditions. In addition to its typical innate immune functions, CRIg was shown to directly and indirectly influence adaptive immune responses. Here, we review our current understanding of the diverse roles of CRIg in pathogen elimination, anti-microbial immunity and autoimmunity. In particular, we will explore how, through selective capturing by CRIg, an important balance is achieved between the immunological and clearance functions of liver and spleen.

Alcohol Modulation of the Postburn Hepatic Response

The widespread and rapidly increasing trend of binge drinking is accompanied by a concomitant rise in the prevalence of trauma patients under the influence of alcohol at the time of their injury. Epidemiological evidence suggests up to half of all adult burn patients are intoxicated at the time of admission, and the presence of alcohol is an independent risk factor for death in the early stages post burn. As the major site of alcohol metabolism and toxicity, the liver is a critical determinant of postburn outcome, and experimental evidence implies an injury threshold exists beyond which burn-induced hepatic derangement is observed. Alcohol may lower this threshold for postburn hepatic damage through a variety of mechanisms including modulation of extrahepatic events, alteration of the gut-liver axis, and changes in signaling pathways. The direct and indirect effects of alcohol may prime the liver for the second-hit of many overlapping physiologic responses to burn injury. In an effort to gain a deeper understanding of how alcohol potentiates postburn hepatic damage, the authors summarize possible mechanisms by which alcohol modulates the postburn hepatic response.

Tissue macrophages as mediators of a healthy relationship with gut commensal microbiota

Mammals and microorganisms have evolved a complex and tightly controlled mutual relationship. This interaction grants protection and energy source for the microorganisms, and on the other hand, provides several immunologic, metabolic and physiological advantages for the host. The gastrointestinal tract (GI) harbors the largest bacteria diversity within the body and complex mechanisms control microbiota community under homeostasis. However, once disrupted, microbiota imbalance can lead to overt growth of resident and invasive populations, with potential risk for lethal diseases. In these cases, bacteria might also escape from the intestines and reach different organs through the blood and lymphatic circulation. To control these unwanted conditions, all body tissues are populated with resident macrophages that have the ability to capture and eliminate pathogens, avoiding their dissemination. Here we discuss the different routes for bacterial translocation from the intestinal tract, and how macrophages act in the removal of these microorganisms to prevent systemic infections and restore the homeostasis.

Old dogs-new tricks: immunoregulatory properties of C3 and C5 cleavage fragments

The activation of the complement system by canonical and non-canonical mechanisms results in the generation of multiple C3 and C5 cleavage fragments including anaphylatoxins C3a and C5a as well as opsonizing C3b/iC3b. It is now well appreciated that anaphylatoxins not only act as pro-inflammatory mediators but as immunoregulatory molecules that control the activation status of cells and tissue at several levels. Likewise, C3b/iC3b is more than the opsonizing fragment that facilitates engulfment and destruction of targets by phagocytes. In the circulation, it also facilitates the transport and delivery of bacteria and immune complexes to phagocytes, through a process known as immune adherence, with consequences for adaptive immunity. Here, we will discuss non-classical immunoregulatory properties of C3 and C5 cleavage fragments. We highlight the influence of anaphylatoxins on Th2 and Th17 cell development during allergic asthma with a particular emphasis on their role in the modulation of CD11b⁺ conventional dendritic cells and monocyte-derived dendritic cells. Furthermore, we discuss the control of anaphylatoxin-mediated activation of dendritic cells and allergic effector cells by adaptive immune mechanisms that involve allergen-specific IgG1 antibodies and plasma or regulatory T cell-derived IL-10 production. Finally, we take a fresh look at immune adherence with a particular focus on the development of antibacterial cytotoxic T-cell responses.

Monocytes/Macrophages Mobilization Orchestrate Neovascularization after Localized Colorectal Irradiation

In patients undergoing radiotherapy for cancer, radiation dose to healthy tissue can occur, causing microvascular damage. Monocytes that have been shown to promote tissue revascularization comprise the subsets: CD11b⁺Ly6G^-7/4^hi/monocytes^hi and CD11b⁺Ly6G^-7/4^lo/monocytes^lo. We hypothesized that monocytes were implicated in postirradiation blood vessel formation. C57Bl6 mice underwent localized colorectal irradiation and were sacrificed at different times after exposure. Bone marrow, spleen, blood and colon were collected. Fourteen days postirradiation, colons expressed proangiogenic actors and adhesion molecules. Monocytes^hi, which were the main subset of infiltrating monocytes, mobilized to the blood from spleen and bone marrow, peaking at day 14 postirradiation, and were associated with lymphocyte Th1 polarization. At day 28 postirradiation, angiographic score and capillary density increased by ∼1.8-fold, and then returned to nonirradiated levels at day 60. Clodronate-mediated depletion of circulating monocytes prior to irradiation resulted in a ∼1.4-fold decrease in angiographic score and capillary density compared to the nontreated control. Histological analysis of the colon in clodronate-treated mice revealed a massive decrease of macrophage and lymphocyte infiltration as well as reduced collagen deposition in crypt area at day 21. However, late depletion of monocytes from day 25 postirradiation had no effect on fibrotic process. These findings demonstrate a central role for monocyte/macrophage activation in the orchestration of a neovascularization mechanism after localized colorectal irradiation.

Targeting CD64 mediates elimination of M1 but not M2 macrophages in vitro and in cutaneous inflammation in mice and patient biopsies

Macrophages are key players in controlling the immune response that can adapt to microenvironmental signals. This results in distinct polarization states (classical M1 or alternative M2), that play a differential role in immune regulation. In general, the M1 contribute to onset of inflammation, whereas the M2 orchestrate resolution and repair, whereby failure to switch from predominantly M1 to M2 reinforces a pro-inflammatory environment and chronic inflammation. Here, we show selective elimination of M1 macrophages in vitro by a range of CD64-targeted immunotoxins, including H22(scFv)-ETA'. After re-polarization of already polarized macrophages, still only M1 polarization showed sensitivity toward CD64-directed immunotoxins. The selectivity for M1 was found linked to reduced endosomal protease activity in M1 macrophages as demonstrated by inhibition of endosomal proteases. Using the H22(scFv)-ETA' in a transgenic mouse model for chronic cutaneous inflammation, the M1 specificity was confirmed in vivo and a beneficial effect on inflammation demonstrated. Also ex vivo on skin biopsies from atopic dermatitis and diabetes type II patients with chronically-inflamed skin, a clear M1 specific effect was found. This indicates the potential relevance for human application. Our data show that targeting M1 macrophages through CD64 can be instrumental in developing novel intervention strategies for chronic inflammatory conditions.

Comparative study of bacterial translocation control with nitric oxide donors and COX2 inhibitor

OBJECTIVE AND DESIGN

To evaluate the beneficial effects of exogenous NO and an inhibitor of the COX2, and their action levels in a model of SIRS/bacterial translocation (BT) induced by Zymosan A(®).

MATERIAL AND METHODS

Ninety Wistar rats were submitted to different treatments, and after 12h and 24h they were anaesthetized in order to collect blood, mesenteric lymph nodes, and kidney for subsequent biochemical analyses and microbiological examinations.

TREATMENTS

A nitric oxide donor, Molsidomine(®), was compared with a COX2 inhibitor, Celecoxib(®).

METHODS

Zymosan A(®) was administered to Wistar rats. The animals were divided into 6 groups: one group for survival study, Group (1) No manipulation (BASAL); Group (2) vehicle of Zymosan A(®) given intraperitoneally (SHAM); Group I (control), with Zymosan A(®) (0.6g/kg) intraperitoneally; Group II (Molsidomine), with Molsidomine(®) (4mg/kg) through the penis dorsal vein, 30min prior to administration of the Zy(®) (0.6g/kg); Group III (Celecoxib), with Celecoxib(®) (400mg/kg) orally through a stomach tube, 6h prior to administration of the Zy (0.6g/kg).

DETERMINATIONS

The parameters survival, bacterial translocation, renal function, neutrophil accumulation, oxygen free radicals (OFR), detoxifying enzymes, and cytokines were measured at different times after Zymosan administration.

RESULTS

The model established induced a mortality rate of 100% and generated BT and systemic inflammatory response syndrome (SIRS) in all samples. It also significantly increased all variables, with p<.001 for MPO and all pro-inflammatory cytokines, and p<.01 for all OFR. Treatment with Molsidomine reduced mortality to 0%, decreased BT, MPO, pro-inflammatory cytokines and OFR (p<.001) significantly and increased IL-10 and IL-6 production. Moreover, the Celecoxib(®) showed a lower capacity for SIRS regulation.

CONCLUSIONS

The exogenous administration of NO prevented BT and controlled SIRS. Therefore these results suggest that Molsidomine could be used as a therapeutic strategy to protect against BT.

Heat stroke

Heat stroke is a life-threatening condition clinically diagnosed as a severe elevation in body temperature with central nervous system dysfunction that often includes combativeness, delirium, seizures, and coma. Classic heat stroke primarily occurs in immunocompromised individuals during annual heat waves. Exertional heat stroke is observed in young fit individuals performing strenuous physical activity in hot or temperature environments. Long-term consequences of heat stroke are thought to be due to a systemic inflammatory response syndrome. This article provides a comprehensive review of recent advances in the identification of risk factors that predispose to heat stroke, the role of endotoxin and cytokines in mediation of multi-organ damage, the incidence of hypothermia and fever during heat stroke recovery, clinical biomarkers of organ damage severity, and protective cooling strategies. Risk factors include environmental factors, medications, drug use, compromised health status, and genetic conditions. The role of endotoxin and cytokines is discussed in the framework of research conducted over 30 years ago that requires reassessment to more clearly identify the role of these factors in the systemic inflammatory response syndrome. We challenge the notion that hypothalamic damage is responsible for thermoregulatory disturbances during heat stroke recovery and highlight recent advances in our understanding of the regulated nature of these responses. The need for more sensitive clinical biomarkers of organ damage is examined. Conventional and emerging cooling methods are discussed with reference to protection against peripheral organ damage and selective brain cooling.

Role of pentoxifylline and sparfloxacin in prophylaxis of spontaneous bacterial peritonitis in cirrhotic patients

This study was directed to evaluate the role of sparfloxacin and pentoxifylline in the prophylaxis of spontaneous bacterial peritonitis in cirrhotic patients. Forty cirrhotic patients with ascites were included in the study. Patients were randomized into four groups in a blind fashion; each group consists of ten patients. Group one received ciprofloxacin (control group), group two received sparfloxacin, group three received pentoxifylline, and group four received a combination of sparfloxacin and pentoxifylline. Treatment duration was six months. Serum TNF-α level was the primary inflammatory marker of the study to evaluate the effect of the used medications. In group two, TNF-α level showed a statistically significant decrease in comparison with group one (P = 0.001), while in group three, TNF-α level showed nonsignificant difference in comparison with the control group (P > 0.05). In addition, group four showed a statistically significant decrease in TNF-α level compared to the other three groups (P < 0.05). The finding from our study indicates that sparfloxacin as well as pentoxifylline could be used in prophylaxis of spontaneous bacterial peritonitis. Combination of sparfloxacin and pentoxifylline showed some of synergism which may be useful in decreasing emergence of resistant strains.

GITR gene deletion and GITR-FC soluble protein administration inhibit multiple organ failure induced by zymosan

Multiple organ dysfunction syndrome (MODS) is a systemic inflammatory event that can result in organ damage, failure, and high risk of mortality. The aim of this study was to evaluate the possible role of glucocorticoid-induced TNFR-related (GITR) on zymosan-induced MODS. Mice were allocated into one GITR knockout (GITR-KO) and two GITR wild-type (GITR-WT) experimental groups. All the animals were treated with zymosan (500 mg/kg, suspended in saline solution, i.p.), and animals of one GITR-WT group received GITR-Fc (6.25 μg/mouse; 3 h after zymosan injection) by mini-osmotic pump. Moreover, three control groups were performed (one GITR-KO and two GITR-WT experimental groups), administering saline instead of zymosan and treating one of the GITR-WT group with GITR-Fc (6.25 μg/mouse; 3 h after saline injection) by mini-osmotic pump. A number of inflammatory parameters such as edema formation, histological damage, adhesion molecules expression, neutrophil infiltration, proinflammatory cytokines, nitrotyrosine, and iNOS production are significantly reduced in GITR-KO as compared with GITR-WT mice as well as in GITR-WT mice treated with GITR-Fc. We here show that GITR plays a role in the modulation of experimental MODS. In particular, we show that genetic inhibition of GITR expression, in GITR-KO mice, or administration of soluble GITR-Fc receptor in GITR-WT mice, reduces inflammation, organ tissue damage, and mortality. Results, while confirming the proinflammatory role of GITR, extend our observations indicating that GITR plays a role in zymosan-induced inflammation and MODS.

Intracellular pathogen sensor NOD2 programs macrophages to trigger Notch1 activation

Intracellular pathogen sensor, NOD2, has been implicated in regulation of wide range of anti-inflammatory responses critical during development of a diverse array of inflammatory diseases; however, underlying molecular details are still imprecisely understood. In this study, we demonstrate that NOD2 programs macrophages to trigger Notch1 signaling. Signaling perturbations or genetic approaches suggest signaling integration through cross-talk between Notch1-PI3K during the NOD2-triggered expression of a multitude of immunological parameters including COX-2/PGE(2) and IL-10. NOD2 stimulation enhanced active recruitment of CSL/RBP-Jk on the COX-2 promoter in vivo. Intriguingly, nitric oxide assumes critical importance in NOD2-mediated activation of Notch1 signaling as iNOS(-/-) macrophages exhibited compromised ability to execute NOD2-triggered Notch1 signaling responses. Correlative evidence demonstrates that this mechanism operates in vivo in brain and splenocytes derived from wild type, but not from iNOS(-/-) mice. Importantly, NOD2-driven activation of the Notch1-PI3K signaling axis contributes to its capacity to impart survival of macrophages against TNF-α or IFN-γ-mediated apoptosis and resolution of inflammation. Current investigation identifies Notch1-PI3K as signaling cohorts involved in the NOD2-triggered expression of a battery of genes associated with anti-inflammatory functions. These findings serve as a paradigm to understand the pathogenesis of NOD2-associated inflammatory diseases and clearly pave a way toward development of novel therapeutics.

Novel insights for systemic inflammation in sepsis and hemorrhage

The inflammatory responses in sepsis and hemorrhage remain a major cause of death. Clinically, it is generally accepted that shock in sepsis or hemorrhage differs in its mechanisms. However, the recognition of inflammatory cytokines as a common lethal pathway has become consent. Proinflammatory cytokines such as tumor necrosis factor (TNF) or high-mobility group box1 (HMGB1) are fanatically released and cause lethal multiorgan dysfunction. Inhibition of these cytokines can prevent the inflammatory responses and organ damage. In seeking potential anti-inflammatory strategies, we reported that ethyl pyruvate and alpha7 nicotinic acetylcholine receptor (alpha7nAChR) agonists effectively restrained cytokine production to provide therapeutic benefits in both experimental sepsis and hemorrhage. Here, we review the inflammatory responses and the anti-inflammatory strategies in experimental models of sepsis and hemorrhage, as they may have a consistent inflammatory pathway in spite of their different pathophysiological processes.

Phagocytosis of gadolinium chloride or zymosan induces simultaneous upregulation of hepcidin- and downregulation of hemojuvelin- and Fpn-1-gene expression in murine liver

The liver and the spleen are the organs in which cellular material and aged erythrocytes are eliminated from the blood. Within the liver, Kupffer cells (KCs) are mainly responsible for this task, as such KCs have a pivotal role in iron metabolism. The aim of this study is to investigate the changes of hepatic gene expression in two models of KC phagocytosis. Gadolinium chloride (GD) or zymosan was injected intraperitoneally into rats and to endotoxin-resistant mice (C3H/HeJ). The animals were killed at different time points and their livers were immediately frozen in liquid nitrogen for RNA isolation and immunohistological studies. RNA was analyzed by real-time PCR and northern blot. Sera were used to measure transaminases, hepcidin and iron levels. The expression of iron metabolism genes, hepcidin, hemojuvelin (Hjv), ferroportin-1 (Fpn-1) and of the inflammatory cytokines IL-6, IL-1beta, TNF-alpha and IFN-gamma was determined. Although phagocytosed material was detected in ED-1- and C1q-positive cells, no inflammatory cells were identified within the liver parenchyma. Serum levels of hepcidin, iron and transaminases did not differ from those of control animals. Both GD and zymosan induced an upregulation of hepcidin-gene expression in rat liver as early as 3 h, reaching a maximum 6 h after treatment. Hjv- and Fpn-1-gene expression was downregulated at the same time. IL-6 was by far the most induced acute-phase-cytokine in GD- and zymosan-treated livers, although IL-1beta and TNF-alpha were also strongly upregulated by zymosan and to a lesser extent by GD. Similar results were obtained in the C3H/HeJ mouse strain excluding the possible role of contaminating endotoxin. This study shows that phagocytosis upregulates hepcidin-gene expression and downregulates Hjv- and Fpn-1-gene expression within the liver. These changes in iron-regulating-gene expression may be mediated by the locally produced acute-phase-cytokines.

Scientific and clinical challenges in sepsis

Advances in intensive care and antibiotics have prevented the spread of some infections, though sepsis mortality rates remain high. With failure of over thirty clinical trials, sepsis remains a scientific and clinical challenge in modern medicine. Sepsis is defined by the clinical signs of a systemic inflammatory response to infection. "Severe sepsis" is when these symptoms are associated with multiple organ dysfunction. These definitions of sepsis may be too broad and common to heterogeneous groups of patients who do not necessarily have the same disorder. This consideration has become especially evident in the clinical trials that have failed to obtain consistent results in similar studies of patients diagnosed with severe sepsis. In these trials, patients with infections caused by different microorganisms, and affecting different organs, have been combined under the general diagnosis of severe sepsis. The situation is analogous to attempting a clinical trial based on the general definition of cancer, combining all patients with tumor independent of the type of malignancy. In this consideration, it would not be very surprising that activated protein C, the only treatment in sepsis approved by the Food and Drug Administration, is projected for use in only a small subset of patients with severe sepsis. This article reviews novel inflammatory molecular aspects and the experimental anti-inflammatory strategies for sepsis, as they may represent particular pathological processes in specific subsets of patients.

The immunological consequences of injury

Immediate and early trauma death rates are determined by "first hits" such as hypoxia, hypotension and organ injury, while late mortality correlates closely with "second hits" such as infection. An imbalance between the early systemic inflammatory response (SIRS), and the later compensatory counter-inflammatory response (CARS), is considered to be responsible for much post-traumatic morbidity and mortality. From a clinical perspective, this remains a significant healthcare problem, which has stimulated decades of experimental and clinical research aimed at understanding the functional effects of injury on the immune system. This review describes the impact of injury on the innate and adaptive immune systems. Though it is worth noting that the features of the immune response to injury overlap in many areas with immune dysregulation in sepsis, we attempt here to elucidate the mechanism by which injury predisposes to infection rather than to describe the alterations in host immunity consequent to established sepsis.

Zymosan-induced generalized inflammation: experimental studies into mechanisms leading to multiple organ dysfunction syndrome

Patients suffering from multiple organ dysfunction syndrome (MODS) comprise a heterogeneous population, which complicates research in its pathogenesis. Elucidation of the mechanisms involved in the development of MODS will ultimately necessitate the collection of tissue samples and the performance of invasive procedures. These requirements greatly reduce the possibilities for research in human subjects. Therefore, an animal model for MODS is a necessary and valuable tool. In the mid 1980s, the zymosan-induced generalized inflammation (ZIGI) model was introduced. Intraperitoneal injection of zymosan in mice or rats leads, in the course of 1 to 2 weeks, to increasing organ damage and dysfunction. The ZIGI model has been recognized as the one that best resembles human MODS and it has been used widely to study systemic inflammation in relation to organ failure. This review describes the ZIGI model and gives an overview of the results obtained.

Pancreatic enzymes sustain systemic inflammation after an initial endotoxin challenge

BACKGROUND

Sepsis is accompanied by severe inflammation whose mechanism remains uncertain. We recently demonstrated that pancreatic proteases in the ischemic intestine have the ability to generate powerful inflammatory mediators that can be detected in the portal vein and in the general circulation. This study was designed to examine several circulatory and inflammatory indices during experimental endotoxemia and intraintestinal pancreatic protease inhibition.

METHODS

Immediately after intravenous endotoxin administration, the small intestine was subjected to intraluminal lavage with and without gabexate mesilate, an inhibitor of pancreatic proteases. Shams and rats without lavage served as controls. Hemodynamics, leukocyte (neutrophil and monocyte), and endothelial cell activation, as well as organ injury in the intestine and the cremaster muscle, were examined.

RESULTS

After endotoxin administration, control rats developed hypotension, tachycardia, hyperventilation, and leukopenia. The intestine and plasma contained mediators that activated leukocytes. The leukocyte-endothelial interaction within the cremaster muscle microcirculation was enhanced. Endotoxin administration resulted in elevated interleukin-6 plasma levels. Histologic evidence indicated liver and intestinal injury. In contrast, blockade of pancreatic proteases in the intestinal lumen significantly improved hemodynamic parameters and reduced all indices of inflammation in plasma and cell injury in skeletal muscle microcirculation.

CONCLUSIONS

Inflammatory mediators derived from the intestine by pancreatic proteases may be involved in the prolonged inflammatory response and sustain symptoms of sepsis after endotoxin challenge.

Influences of thoracic duct blockage on early enteral nutrition for patients who underwent esophageal cancer surgery

OBJECTIVES

We have previously reported the beneficial effects of immediate enteral nutrition (EN) after esophageal cancer surgery. This randomized control study was conducted to determine whether immediate EN is beneficial or not for patients whose thoracic ducts were ligated, as well as those whose thoracic ducts were preserved.

PATIENTS AND METHODS

Thirty-nine patients who underwent radical resection of the esophageal cancer entered this trial. After stratifying into two groups--patients whose thoracic ducts were preserved [D(+)] and those whose thoracic ducts were ligated [D(-)], they were randomly divided into two groups--the patients who received early EN and those who received parenteral nutrition (PN) followed by delayed enteral feeding. Thus, the number of patients in the D(+)-EN group, D(+)-PN group, D(-)-EN group and D(-)-PN group were 13, 12, 7 and 7, respectively. The mortality and morbidity rates, and several blood chemistries were compared between the EN groups and the PN groups.

RESULTS

Total lymphocyte count showed a significant early increase and serum c-reactive protein (CRP) was significantly decreased in the D(+)-EN group compared to the D(+)-PN group. However those differences were not observed between the D(-) groups. Serum total bilirubin was significantly decreased in the both EN groups compared to the PN groups. The mortality and morbidity rates were not different between the EN group and the PN group in the D(+) patients and also in the D(-) patients.

CONCLUSIONS

Patients whose thoracic ducts were ligated did not obtain any other benefit from early enteral feeding except for bilirubin metabolism. Early enteral feeding is not recommended for patients whose thoracic ducts are ligated during radical resection of a cancer in the thoracic esophagus.

Liposomal clodronate as a novel agent for treating autoimmune hemolytic anemia in a mouse model

Autoimmune hemolytic anemia (AIHA) is a disease in which autoantibodies against red blood cells (RBCs) lead to their premature destruction. Most clinically significant autoantibodies are of the immunoglobulin G (IgG) type, which leads primarily to the uptake and destruction of RBCs by splenic and hepatic macrophages. Therapies such as corticosteroids and splenectomy are directed at interfering with this process. Liposomally encapsulated clodronate (dichloromethylene diphosphonate) has previously been found to be a potent antimacrophage agent. It selectively depletes animals of macrophages within 24 hours of administration by inducing apoptosis in these cells. Therefore, we hypothesized that liposomal clodronate would be a useful agent for treating AIHA. We tested this hypothesis in a mouse model of AIHA in which animals were given either anti-RBC antibodies or preopsonized RBCs. In either case, liposomal clodronate substantially decreased RBC destruction. This drug formulation was effective within hours by first blocking and then depleting phagocytic macrophages, and its action lasted for 1 to 2 weeks. Thus, in AIHA, liposomal clodronate therapy may act like a temporary, medicinal splenectomy. As such, it may prove useful in situations where rapid response to therapy is critical or other medical therapies are inadequate.

Portal versus systemic drainage of small bowel allografts: comparative assessment of survival, function, rejection, and bacterial translocation

BACKGROUND

Portal venous drainage of small bowel grafts is theoretically more physiologic than systemic drainage, but is technically more demanding. Comparisons in animal models have not demonstrated a clear advantage of one technique over the other, but clinical data are lacking.

STUDY DESIGN

Clinical records of 36 patients who underwent 37 small bowel transplantation procedures from January 1995 to August 2001 were reviewed. Portal drainage was performed in 19 patients (PD group). Systemic drainage was performed in 18 patients (SD group). Median followup was 531 days.

RESULTS

PD and SD patients had similar ICU stays (median 7 versus 9 days) and endotracheal intubation durations (median 3 versus 5 days). All current survivors, with the exception of one patient in each group, are independent from parenteral nutrition. Liver function tests were similar in both groups. There was a twofold increase in tacrolimus dosage in the PD group to achieve similar trough levels indicating a "first-pass" hepatic clearance effect. Cumulative incidence of acute rejection episodes and OKT3-requiring rejection episodes were similar in both groups. To the contrary, a lower incidence of gram-negative rods of Enterococcus sp. in blood or bronchoalveolar lavage suggested that the clearance of translocated intestinal bacteria was more efficient in the PD group. Graft and patient survival rates were similar in both groups.

CONCLUSIONS

Systemic venous drainage of small bowel transplants is a dependable technique, associated with similar results as portal venous drainage, in terms of overall mortality, morbidity, rejection, function, and patient and graft survival. But attention should be paid to an impaired clearance of intestinal bacterial translocation after systemic drainage.

The effects of pentoxifylline on bacterial translocation after intestinal obstruction

Bacterial translocation (BT) occurs mainly in preseptic conditions such as intestinal obstruction, trauma, and burn, and the underlying mechanisms are still unclear. Pentoxifylline (PTX) is a derivative of methyl xanthine and has several beneficial effects in sepsis. We investigated the effects of PTX on a rat BT model. Simple intestinal obstruction (IO) was choosen to create high BT rates. Rats were divided in to five groups of 10 rats. Either 50 mg/kg PTX or placebo (3 mg/100 g saline) was administered subcutaneously following IO, either by single injection or twice with a 12-h interval. All rats were sacrificed 12 or 24 h after the procedure, and mesenteric lymph nodes (MLN), liver, and blood samples were obtained under aseptic conditions for bacterial cultures. The samples were obtained 12 h following IO in the first two groups, and the same samples were obtained 24 h after IO in last three groups. Groups IV and V were the PTX treatment groups. PTX was re-injected 12 h after IO only in group IV. As a result, BT rates in MLNs and liver were found to be significantly low, blood specimens remained sterile in PTX-pretreated and -treated rats, and BT rates were high in control groups and group V (once treatment late specimen group). We conclude that simple intestinal obstruction causes BT, and PTX reduces BT in rats with IO during the first 12-h period if PTX is given once immediately following IO. PTX reduces BT during the first 24-h after IO provided that is injected twice with a 12-h interval. More experimental studies are need to explain the exact mechanism of this beneficial effect.

n-3 Polyunsaturated fatty acid-enriched diet does not protect from liver injury but attenuates mortality rate in a rat model of systemic endotoxemia

OBJECTIVE

We investigated the potential of dietary fish oil containing n-3 polyunsaturated fatty acids to attenuate hepatic injury and mortality rate of rats in response to systemic endotoxemia.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University laboratory.

SUBJECTS

A total of 43 male Sprague Dawley rats.

INTERVENTIONS

Rats were fed either fish oil supplement or regular standard lab chow. After 8 wks of feeding, each diet group was subjected to a single exposure of lipopolysaccharide (Escherichia coli, 10 mg/kg intravenously) or saline. Hepatic microvascular response and liver injury were assessed by in vivo analysis of Kupffer cell phagocytic activity, leukocyte-endothelial cell interaction, nutritive sinusoidal perfusion failure, and parenchymal cell apoptosis (intravital fluorescence epi-illumination technique) as well as bile flow, serum liver enzyme activities, and tissue histomorphology.

MEASUREMENTS AND MAIN RESULTS

In animals fed a standard diet, livers at 16 hrs after lipopolysaccharide-exposure exhibited depressed Kupffer cell phagocytic activity, enhanced hepatic microvascular leukocyte activation, leukocytic tissue infiltration, sinusoidal perfusion failure, and parenchymal cell apoptosis. Hepatic microvascular injury was further accompanied by reduced bile flow and enhanced liver enzyme release. The fish oil enriched diet did not significantly change the multiple features of endotoxemia-associated liver injury; however, it maintained arterial blood pressure, systemic leukocyte count, and acid base balance and showed a tendency toward improved survival on lipopolysaccharide exposure with a 16 hr-survival rate of 80% (p =.06 vs. survival rate of 40% in animals fed a regular diet). Moreover, slightly increased serum concentrations of interleukin-10 coincided with enhanced concentrations of interleukin-6 in fish oil fed endotoxemic animals. Healthy, non-lipopolysaccharide-exposed, fish oil fed animals did not differ from those fed with the regular diet, except for dampened Kupffer cell phagocytic activity.

CONCLUSIONS

Fish oil feeding does not protect from local endotoxemia-induced hepatic microvascular dysfunction. However, dietary modulation of inflammatory mediator response by macrophages, constituting an appropriate immune response, could add to the survival advantage seen in fish oil-fed animals on exposure to lipopolysaccharide.

A mouse model for postoperative fatal enteritis due to Staphylococcus infection

BACKGROUND

Postoperative infection of intestine with methicillin-resistant Staphylococcus aureus (MRSA) is fatal in some cases. The object of this study was to establish a mouse model for the infection, providing a useful tool for investigating mechanisms in the progression of infection.

METHODS

Mice were pretreated with cyclophosphamide, injected orally or directly into jejunum with MRSA prepared from a postoperative patient, and then given 5 daily doses of antibiotics. Forty-eight hours after the injection, bacterial translocation and serum endotoxin levels were examined. Macrophage depletion was carried out by the administration of liposome-encapsulated dichloromethylene diphosphate (Cl(2)MDP), 4 days before MRSA injection.

RESULTS

Injection into the jejunum but not oral administration of MRSA induced enteritis with diarrhea and resulted in death in most cyclophosphamide-treated mice. Translocation of MRSA in mesenteric lymph nodes and liver was observed, concomitantly with E. coli infection. Endotoxin-resistant C3H/HeJ mice infected with MRSA survived longer than endotoxin-sensitive C3H/He mice, but also died within a week after MRSA injection. Selective depletion of macrophages induced infection in mice that were not pretreated with cyclophosphamide.

CONCLUSION

We established a mouse model for the fatal MRSA infection which induced enteritis with diarrhea, that will be a useful tool for investigating the mechanisms for sometimes fatal MRSA infection of the intestine in postoperative patients. The presence of E. coli or endotoxin seemed to play a major role in the mortality of mice in the early days of MRSA-induced enteritis, but other factors, probably from MRSA, in the later days. Phagocytes were quite important for protection against the MRSA infection.

Gut gavage with antiendotoxin antibodies reduces the liberation of tumor necrosis factor-alpha after hemorrhage/resuscitation

OBJECTIVE

To evaluate the effect of gut gavage both alone and with enteral administration of monoclonal antibodies to endotoxin on the liberation of tumor necrosis factor (TNF)-alpha and subsequent hemodynamics after hemorrhage/resuscitation.

DESIGN

Dose response intervention, sham-controlled animal study.

SETTING

Research laboratory at a university medical center.

ANIMALS

Instrumented rats (250-325 g body weight) underwent standardized hemorrhage/resuscitation.

INTERVENTIONS

Animal groups received 4 hrs before hemorrhage/resuscitation: gastric gavage with Colyte alone (group 1), combined with E5 antiendotoxin at either 0.2 mg/100 g (group 2) or 2 mg/100 g body weight (group 3), or sham controls (group 4). There were six animals studied in each of the four groups.

MEASUREMENTS AND MAIN RESULTS

For animals receiving gut gavage and high-dose E5 antiendotoxin, plasma concentrations of TNF-alpha (pg/mL) at 120 mins after hemorrhage/resuscitation were significantly lower compared with sham controls (16+/-4 group 3; 65+/-36 group 4; mean +/- SD, p < .05). At 300 mins, this same treatment group had a significantly higher mean blood pressure (mm Hg) (110+/-6 group 3; 86+/-7 group 4: p < .05). Also at 300 mins after hemorrhage/resuscitation, plasma lactate concentrations (mmol/L) were significantly lower for all gut gavage treatment groups compared with sham control animals (1.9+/-0.2 group 1; 2.0+/-0.2 group 2; 1.8+/-0.2 group 3; 4.8+/-2.8 group 4, p < .05).

CONCLUSIONS

Prior treatment with gut gavage and enterally administered antiendotoxin antibodies reduces TNF-alpha liberation after hemorrhage/resuscitation and confers a subsequent improvement in hemodynamics and decreased plasma lactate concentrations. Such therapy may be efficacious in patients undergoing elective procedures where major hemorrhage is likely or in severely injured patients with continued or recurrent hemorrhage.

The gut: the 'motor' of multiple organ dysfunction syndrome?

Abnormal colonization, gut-origin infections, and bacterial translocation are all signs of gut dysfunction that may be implicated in the pathogenesis of multiple organ dysfunction syndrome (MODS). This review summarizes and updates relevant experimental and clinical data that have attempted to correlate these phenomena with the development of MODS and to answer whether or not the gut is the 'motor' of MODS. The presented data suggest that, in some patients, gut dysfunction may precede the development of MODS. However, in most patients, this relationship is less obvious. The gut may still be one of the motors of MODS; however, it does not appear that this motor is fueled by the systemic spread of bacteria. Bacteria may play a role on a local gut-associated level in initiating and perpetuating the production of local inflammatory mediators that may produce distant organ injury.

Thoracic duct in patients with multiple organ failure: no major route of bacterial translocation

OBJECTIVE

To determine whether translocation of bacteria or endotoxin occurred into the thoracic duct in patients with multiple organ failure (MOF).

SUMMARY BACKGROUND DATA

Translocation of bacteria or endotoxin has been proposed as a causative factor for MOF in patients without an infectious focus, although it has rarely been demonstrated in patients at risk for MOF. Most studies have investigated the hematogenic route of translocation, but it has been argued that lymphatic translocation of bacteria or endotoxin by the thoracic duct is the major route of translocation.

METHODS

The thoracic duct was drained for 5 days in patients with MOF caused either by generalized fecal peritonitis (n = 4) or by an event without clinical and microbiologic evidence of infection (n = 4). Patients without MOF who were undergoing a transthoracic esophageal resection served as controls. In lymph and blood, concentrations of endotoxin, proinflammatory cytokines, and antiinflammatory cytokines were measured.

RESULTS

Endotoxin concentrations in lymph and blood of patients with MOF ranged from 39 to 63 units per liter and were not significantly different from concentrations in patients without MOF. The quantity of endotoxin transported by the thoracic duct in the study group was small. In patients with MOF, low levels of proinflammatory cytokines and high levels of antagonists of these cytokines were found.

CONCLUSION

This study provides evidence that translocation (especially of endotoxin) occurs into the thoracic duct. However, these data do not support the concept that the thoracic duct is a major route of bacterial translocation in patients with MOF.

Protective effect of melatonin on cellular energy depletion mediated by peroxynitrite and poly (ADP-ribose) synthetase activation in a non-septic shock model induced by zymosan in the rat

DNA single-strand breakage and activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS) triggers an energy-consuming, inefficient repair cycle, which contributes to peroxynitrite-induced cellular injury. Recently it was proposed that zymosan, a non-bacterial agent, causes cellular injury by inducing the production of peroxynitrite and consequent PARS activation. Here we investigated whether in vivo melatonin treatment inhibits cellular injury induced by peroxynitrite production and PARS activation in macrophages collected from rats subjected to zymosan-induced shock. Macrophages harvested from the peritoneal cavity exhibited a significant production of peroxynitrite, as measured by the oxidation of the fluorescent dye dihydrorhodamine 123. Furthermore, zymosan-induced shock caused a suppression of macrophage mitochondrial respiration, DNA strand breakage, activation of PARS and reduction of cellular levels of NAD+. In vivo treatment with melatonin (25 and 50 mg/kg, intraperitoneally, 1 hr after zymosan injection) significantly reduced in dose-dependent manner peroxynitrite formation and prevented the appearance of DNA damage, the decrease in mitochondrial respiration, the loss of cellular levels of NAD+, and the PARS activation. Our study supports the view that the antioxidant and antiinflammatory effect of melatonin is also correlated with the inhibition of peroxynitrite production and PARS activation. In conclusion, melatonin may be a novel pharmacological approach to prevent cell injury in inflammation.

Interleukin-10 reduces morbidity and mortality in murine multiple organ dysfunction syndrome (MODS)

HYPOTHESIS

IL-10 will reduce morbidity and mortality in murine MODS. Introduction. Intraperitoneal (ip) zymosan causes a triphasic inflammatory process leading to MODS. Phase I is an acute systemic inflammatory response to sterile peritonitis. Phase II is the recovery phase. Phase III is characterized by recurrent illness, progressive organ dysfunction, and elevated proinflammatory cytokines.

METHODS

Male ICR mice were randomized (on Experiment Day 0, time = 0 h) into four initial groups (A-D): Control Group A received no zymosan and no IL-10. Group B received zymosan (1 mg/g mouse BW, t = 0) and no IL-10. Group C received no zymosan and IL-10 at t = 2 h. Group D received zymosan and IL-10 at t = 2 h. On Experiment Day 4, mice in Groups B-D were randomized into six further treatment groups (B1 and B2, C1 and C2, D1 and D2). Group B1 received no treatment. Group B2 received IL-10 when clinical signs of recurrent illness developed (Phase III, 12-18 days after zymosan treatment). Mice were sacrificed when they were preterminal (clinical signs of shaking, shivering, or paralysis) or on Experiment Day 28 (survivors). Plasma total bilirubin and creatinine levels were measures of organ function. Terminal pulmonary compliance was measured in situ through a physiologic range of tidal volumes.

RESULTS

Mice entering Phase III consistently progressed to MODS characterized by elevated bilirubin and hemorrhagic lungs which, if left untreated, was lethal. Mice treated with IL-10 (Group B2) when they entered Phase III had lower mortality (28.6% vs 100%, P < 0.02), longer survival (25 vs 18 days, P < 0.05), and improved lung pulmonary compliance (slope beta1 = 0.082 ml/mm Hg vs 0.059 ml/mm Hg, P < 0.001) compared to untreated (Group B1) mice in Phase III.

CONCLUSIONS

IL-10 improves survival even when given after clinical signs of illness are present.

Transient suppression of macrophage functions by liposome-encapsulated drugs

Macrophages play an important role in host defense reactions, for example, by phagocytosis of particulate materials. This process also results in the rapid removal of targeting devices such as liposomes and adenovirus vectors and of non-autologous grafted cells and materials. Another aspect of macrophage function is their production and secretion of proinflammatory cytokines. Transient and organ-specific suppression of macrophage function by liposome-mediated manipulation has been shown to improve the efficacy of drug and gene targeting and to reduce the symptoms of inflammatory reactions.

The relationship between gut-derived bacteria and the development of the multiple organ dysfunction syndrome

Abnormal colonisation, infections of gut origin and bacterial translocation are all signs of gut failure that have been hypothesised as being implicated in the pathogenesis of the multiple organ dysfunction syndrome (MODS). We have summarised published experimental and clinical studies that have tried to correlate the occurrence or prevention of these phenomena with the development of MODS. We conclude that in some patients loss of intestinal barrier function or the onset of infection precedes the development of MODS. In other patients, however, this relationship is not so clear and it seems that these are epiphenoma of critical illness and may reflect a failure of the host's immune and mechanical defence systems. The causal relationship between these phenomena and the development of MODS is complex and needs further clarification.

Role of the gut in the pathophysiology of extrahepatic biliary obstruction

BACKGROUND

Gram negative septic events are the commonest source of morbidity and mortality as a result of surgery in jaundiced patients. The large intestine provides the major source of Gram negative bacteria in mammals and is implicated in the pathogenesis of systemic endotoxaemia in obstructive jaundice. Bile salts have an important part in maintaining indigenous microecological homeostasis through their emulsifying properties.

AIMS

The aim was to investigate the effects of biliary obstruction and isolated external biliary diversion on gastro-intestinal structure and caecal bacterial flora in relation to bacterial translocation.

METHOD

Six groups of adult male Wistar rats were studied (no operation, sham operated, and bile duct ligated (BDL) for one and three weeks and a choledocho-vesical fistula (CDVF) for one week). At the end of the study period plasma was assayed for evidence of endotoxaemia and the animals were tested for bacterial translocation to the mesenteric lymph node complex (MLNC), liver, lungs, and spleen. Quantitative and qualitative bacteriological studies were performed on the caecal contents and segments of colon and terminal ileum were washed and prepared for histological assessment.

RESULTS

Bacterial translocation was significantly increased in the BDL1 (68.8%) and BDL3 (60%) groups compared with the sham1 (6.3%), sham3 (9.1%), No operation (0%), and CDVF1 (16.7%) groups. Although translocation was more pronounced in the BDL1 group, this was almost exclusively to the MLNC compared with the more widespread translocation to other organs in the BDL3 group. The BDL3 group was the only group with significantly raised concentrations of endotoxin and anticore glycolipid. The caecal Gram negative aerobic counts were significantly increased in the BDL1 and CDVF1 groups compared with all other groups. There was evidence of structural abnormalities in the terminal ileum of rats jaundiced for three weeks, but not in the other groups.

CONCLUSIONS

Biliary obstruction for one and three weeks promotes bacterial translocation although the mechanisms may be different. Absence of intralumenal bile results in a significant but self limiting increase in the Gram negative aerobic population, which may account for translocation in the early stages of biliary obstruction. As the duration of biliary obstruction increases systemic endotoxaemia is a consistent feature which, combined with factors such as immunological depression and physical disruption of gut barrier function, may promote bacterial translocation perpetuating systemic sepsis.

Influence of macrophage depletion on bacterial translocation and rejection in small bowel transplantation

Rejection and sepsis can be intimately related following small bowel transplantation when rejection compromises normal intestinal barrier mechanisms and bacterial translocation results. Macrophages play a role in controlling the egress of intestinal luminal bacteria--and they have also been implicated in allograft rejection. In this study, the role of macrophages in rejection and bacterial translocation was evaluated by depleting macrophages in donors and/or recipients of rat small bowel allografts with injection of liposome-encapsulated dichloromethylene diphosphonate (CL2MDP). In preliminary studies, we demonstrated that a single intraperitoneal injection of liposome-encapsulated CL2MDP (350 mg/kg) depleted ED2-positive macrophages by > 90% in the liver mesenteric lymph nodes and proximal and distal small bowel, and by approximately 50% in the spleen. ED1-positive macrophages were depleted by > 90% in the liver and by approximately 50% at the other sites. ED3-positive macrophages were completely depleted. Dendritic cells were > 90% depleted in the spleen and mesenteric lymph nodes, but were not depleted in the small bowel. Macrophage depletion in the donor resulted in increased translocation of bacteria to the peritoneal cavity (P = 0.03) if recipient macrophages were present. With histopathologic analysis, a significantly milder rejection with less arteritis was seen in the allografts of the recipient macrophage-depleted group compared with nondepleted controls (P = 0.045). This suggests that recipient macrophages play an important role in rejection. With macrophage depletion in both the donor and the recipient, graft survival was prolonged significantly (13.2 +/- 1.9 days) compared with non-macrophage-depleted controls (9.2 +/- 1.3 days) (P = 0.003). These studies suggest that strategies targeting recipient macrophages may be useful in controlling small bowel allograft rejection without increasing bacterial translocation.

Deficiency of complement factor C5 reduces early mortality but does not prevent organ damage in an animal model of multiple organ dysfunction syndrome

OBJECTIVE

To evaluate the role of complement factor C5 in a model of zymosan-induced multiple organ dysfunction syndrome.

DESIGN

Experimental animal study.

SETTING

Central animal laboratory of a university hospital.

SUBJECTS

Twenty-five C5-deficient B2D10/Old and 25 C5-sufficient B2D10/New mice.

INTERVENTIONS

On day 0, all mice received an intraperitoneal injection with zymosan suspended in paraffin in a dose of 1 mg/g body weight.

MEASUREMENTS AND MAIN RESULTS

Between days 0 and 12, biological parameters (temperature, body weight, and clinical condition) were measured daily and mortality was monitored. Clinical condition was assessed as a symptom score by blindly grading the degree of lethargy, conjunctivitis, diarrhea, and ruffled fur of each mouse on a 2-point scale (maximum score of 4). On day 12, all surviving mice were killed and relative organ weights of lungs, liver, spleen, and kidneys were calculated. Relative organ weight was defined as (organ weight/body weight) x 100%. Zymosan administration induced a typical triphasic illness. Deterioration of the clinical condition, as indicated by the symptom score, and the decrease in temperature and body weight in the acute phase were all significantly less severe in C5-deficient mice (p < .005). In the late phase, no differences could be noticed in the courses of these biological parameters. Overall mortality was 2 (8%) of 25 in C5-deficient mice and 8 (32%) of 25 in C5-sufficient mice (p = .049), a difference that was mainly due to a difference in the acute phase. Organ damage, assessed as the relative organ weights, did not show any statistical differences for any organ between both strains.

CONCLUSIONS

Complement factor C5 appears to play an important role in the acute hyperdynamic septic response in this model. However, deficiency of C5 could not prevent organ damage in the late multiple organ dysfunction syndrome phase. This finding suggests that other factors must be more important in the development of the inflammatory response leading to multiple organ dysfunction syndrome.

Multiple organ failure: a common problem in surgical intensive care unit patients

The management of the surgical patient with multiple system organ failure remains a formidable problem. Despite advances in critical care, the mortality of multiple organ failure remains unchanged since the syndrome was characterized almost two decades ago. At the present time there are no modalities that can actively reverse established organ failure, hence the treatment of these patients consists of metabolic and haemodynamic support until the process reverses itself or death occurs. Therefore, the best management of the surgical patient at risk for multiple organ failure is prevention of the syndrome. Strategies to avoid organ failure include early fixation of long bone fractures, prompt restoration of perfusion and oxygen delivery, the aggressive diagnosis and drainage of abdominal infection prior to organ failure, early institution of enteral nutrition and the use of specific nutritional substrates and formulas. This review will examine the current theories in the pathogenesis of multiple organ failure and detail two clinical decisions, early stabilization of fractures and prompt re-exploration for suspected abdominal sepsis, that have been associated with a reduction in the frequency of the development of organ failure.