Increased translocation of bacteria from the gastrointestinal tracts of tumor-bearing mice

Systemic Immunoregulatory Consequences of Gut Commensal Translocation

One major determinant of systemic immunity during homeostasis and in certain complex multifactorial diseases (e.g. cancer and autoimmune conditions), is the gut microbiota. These commensals can shape systemic immune responses via translocation of metabolites, microbial cell wall components, and viable microbes. In the last few years, bacterial translocation has revealed itself as playing a key, and potentially causal role in mediating immunomodulatory processes in nongastrointestinal diseases. Moreover, recent observations regarding the presence of complex microbial communities and viable bacteria within gut-distal tissues during homeostasis challenge the current paradigm that healthy mammals are entirely sterile at nonmucosal sites. This review discusses our current understanding of how the gut microbiota orchestrates systemic immunity during noninfectious extraintestinal diseases and homeostasis, focusing on the translocation of viable bacteria to gut-distal sites.

Murine model of chemotherapy-induced extraintestinal pathogenic Escherichia coli translocation

Escherichia coli is a major cause of life-threatening infections in patients with neutropenia, particularly those receiving chemotherapy for the treatment of cancer. In most cases, these infections originate from opportunistic strains living within the patient's gastrointestinal tract which then translocate to major organ systems. There are no animal models that faithfully recapitulate these infections, and, as such, the host or bacterial factors that govern this process remain unidentified. We present here a novel model of chemotherapy-induced bacterial translocation of E. coli. Oral gavage of BALB/c mice with a clinical isolate of extraintestinal pathogenic E. coli (ExPEC) leads to stable and long-term colonization of the murine intestine. Following the induction of neutropenia with the chemotherapeutic drug cyclophosphamide, ExPEC translocates from the intestine to the lungs, liver, spleen, and kidneys with concomitant morbidity in infected animals. Translocation can also occur in mice bearing mammary tumors, even in the absence of chemotherapy. Translocation of ExPEC is also associated with an increase of the diversity of bacterial DNA detected in the blood. This is the first report of a chemotherapy-based animal model of ExPEC translocation in cancerous mice, a system that can be readily used to identify important virulence factors for this process.

Bacteria and tumours: causative agents or opportunistic inhabitants?

Associations between different bacteria and various tumours have been reported in patients for decades. Studies involving characterisation of bacteria within tumour tissues have traditionally been in the context of tumourigenesis as a result of bacterial presence within healthy tissues, and in general, dogma holds that such bacteria are causative agents of malignancy (directly or indirectly). While evidence suggests that this may be the case for certain tumour types and bacterial species, it is plausible that in many cases, clinical observations of bacteria within tumours arise from spontaneous infection of established tumours. Indeed, growth of bacteria specifically within tumours following deliberate systemic administration has been demonstrated for numerous bacterial species at preclinical and clinical levels. We present the available data on links between bacteria and tumours, and propose that besides the few instances in which pathogens are playing a pathogenic role in cancer, in many instances, the prevalent relationship between solid tumours and bacteria is opportunistic rather than causative, and discuss opportunities for exploiting tumour-specific bacterial growth for cancer treatment.

Distribution of pathogens in central line-associated bloodstream infections among patients with and without neutropenia following chemotherapy: evidence for a proposed modification to the current surveillance definition

OBJECTIVE

Many bloodstream infections (BSIs) occurring in patients with febrile neutropenia following cytotoxic chemotherapy are due to translocation of intestinal microbiota. However, these infections meet the National Healthcare Safety Network (NHSN) definition of central line-associated BSIs (CLABSIs). We sought to determine the differences in the microbiology of NHSN-defined CLABSIs in patients with and without neutropenia and, using these data, to propose a modification of the CLABSI definition.

DESIGN

Retrospective review.

SETTING

Two large university hospitals over 18 months.

METHODS

All hospital-acquired BSIs occurring in patients with central venous catheters in place were classified using the NHSN CLABSI definition. Patients with postchemotherapy neutropenia (500 neutrophils/mm(3) or lower) at the time of blood culture were considered neutropenic. Pathogens overrepresented in the neutropenic group were identified to inform development of a modified CLABSI definition.

RESULTS

Organisms that were more commonly observed in the neutropenic group compared with the nonneutropenic group included Escherichia coli (22.7% vs 2.5%; P < .001) but not other Enterobacteriaceae, Enterococcus faecium (18.2% vs 6.1%; P = .002), and streptococci (18.2% vs 0%; P < .001). Application of a modified CLABSI definition (removing BSI with enterococci, streptococci, or E. coli) excluded 33 of 66 neutropenic CLABSIs and decreased the CLABSI rate in one study hospital with large transplant and oncology populations from 2.12 to 1.79 cases per 1,000 line-days.

CONCLUSIONS

Common gastrointestinal organisms were more common in the neutropenia group, suggesting that many BSIs meeting the NHSN criteria for CLABSI in the setting of neutropenia may represent translocation of gut organisms. These findings support modification of the NHSN CLABSI definition.

Progress in genomics, metabolism and biotechnology of bifidobacteria

Members of the genus Bifidobacterium were first described over a century ago and were quickly associated with a healthy intestinal tract due to their numerical dominance in breast-fed babies as compared to bottle-fed infants. Health benefits elicited by bifidobacteria to its host, as supported by clinical trials, have led to their wide application as probiotic components of health-promoting foods, especially in fermented dairy products. However, the relative paucity of genetic tools available for bifidobacteria has impeded development of a comprehensive molecular understanding of this genus. In this review we present a summary of current knowledge on bifidobacterial metabolism, classification, physiology and genetics and outline the currently available methods for genetically accessing and manipulating the genus.

Orally administered bifidobacteria as vehicles for delivery of agents to systemic tumors

Certain bacteria have emerged as biological gene vectors with natural tumor specificity, capable of specifically delivering genes or gene products to the tumor environment when intravenously (i.v.) administered to rodent models. We show for the first time that oral administration of bacteria to mice resulted in their translocation from the gastrointestinal tract (GIT) with subsequent homing to and replication specifically in tumors. The commensal, nonpathogenic Bifidobacterium breve UCC2003 harboring a plasmid expressing lux fed to mice bearing subcutaneous (s.c.) tumors were readily detected specifically in tumors, by live whole-body imaging, at levels similar to i.v. administration. Reporter gene expression was visible for >2 weeks in tumors. Mice remained healthy throughout experiments. Cytokine analyses indicated a significant upregulation of interferon-gamma (IFN-gamma) in the GIT of bifidobacteria-fed mice, which is associated with increases in epithelial permeability. However, B. breve feeding did not increase systemic levels of other commensal bacteria. The presence of tumor was not necessary for translocation to systemic organs to occur. These findings indicate potential for safe and efficient gene-based treatment and/or detection of tumors via ingestion of nonpathogenic bacteria expressing therapeutic or reporter genes.

Relations among circulating monocytes, dendritic cells, and bacterial translocation in patients with intestinal obstruction

BACKGROUND

Little evidence is available regarding the relations among circulating monocytes, dendritic cells (DCs), and bacterial translocation (BT) in patients with intestinal obstruction.

METHODS

We investigated alterations in DCs in mesenteric lymph nodes (MLNs), circulating immune cells (white blood cell, lymphocyte, and monocyte counts), and BT to MLNs in 21 patients undergoing abdominal surgery because of intestinal obstruction. We also examined whether BT correlated with the development of perioperative systemic inflammatory response syndrome (SIRS) and postoperative septic complications.

RESULTS

BT subsequent to intestinal obstruction was observed in 7 (33%) patients. Preoperative circulating immune cell counts were significantly lower in BT-positive patients than those in BT-negative patients. The presence of preoperative SIRS was also significantly related to BT-positive status. A preoperative monocyte count <290/mm(3) was the best predictive factor for BT in MLNs during intestinal obstruction: sensitivity 85.7%; specificity 92.3%; positive and negative predictive values 85.7% and 92.9%, respectively. The area under the receiver operating characteristic curve was 0.944. The expression of S-100 protein-positive DCs in MLNs significantly increased in BT-positive patients.

CONCLUSIONS

A significant inverse correlation was observed between the circulating monocyte count and the ratio of DCs among all cells in MLNs (r(2)= 0.259). Postoperative septic complications were 3.3 times more common in BT-positive patients than in BT-negative patients. A significant increase in the expression of DCs in MLNs was observed in patients with BT subsequent to intestinal obstruction. Our findings suggested that a low monocyte count (<290 /mm(3)) and the presence of preoperative SIRS might be useful factors for predicting BT in patients with intestinal obstruction.

Bacterial translocation may influence the long-term survival in colorectal cancer patients

PURPOSE

The purpose of this study was to investigate the association of bacterial translocation with long-term disease-specific and disease-free survival in colorectal cancer patients.

METHODS

This was a prospective cohort study in which 128 and 30 colorectal cancer patients undergoing curative and palliative resections, respectively, were recruited between 1992 and 1997. Samples of mesenteric lymph nodes were harvested for culture before administration of prophylactic antibiotics. Median follow-up for patients without cancer death was 103 (range, 72-147) months. This cohort of patients was internally validated by Dukes staging.

RESULTS

The cumulative disease-specific survival (time to death) and disease-free survival (time to recurrence) for all patients at five years of follow-up was 55 percent (standard error [SE], 4.4 percent) and 65 percent (SE, 4.8 percent), respectively. Bacteria were isolated from the mesenteric nodes of 23 (15 percent) patients. There was no association between bacterial translocation and nodal metastases, bowel obstruction, and septic complications. Patients with confirmed bacterial translocation had a worse disease-specific survival (n=158, 5-year survivorship estimates+/-SE, 38 percent+/-12 percent vs. 58 percent+/-4.7 percent; P < 0.01) and disease-free survival (n=128, 5-year survivorship estimates+/-SE, 46 percent+/-14 percent vs. 66 percent+/-5 percent; P = 0.004) than those without. Using multivariate Cox regression analysis, bacterial translocation was a predictor of disease-specific survival (P = 0.011) and disease-free survival (P = 0.02) independent of other pathologic prognostic indicators.

CONCLUSION

Colorectal cancer patients with bacterial translocation in the mesenteric lymph nodes have a worse outcome.

N-acetylcysteine reduces respiratory burst but augments neutrophil phagocytosis in intensive care unit patients

OBJECTIVE

The antioxidant N-acetylcysteine (NAC) has been shown to attenuate septic tissue injury. To evaluate whether NAC affects host defense mechanisms in critically ill patients, thus predisposing to increased risk of infection, the current study focuses on neutrophil phagocytotic and burst activity after treatment with NAC.

DESIGN

Prospective, randomized, clinical trial.

SETTING

Twelve-bed operative intensive care unit in a university hospital.

PATIENTS

Thirty patients diagnosed with sepsis/systemic inflammatory response syndrome, or multiple trauma.

INTERVENTIONS

Patients were randomly assigned to receive either NAC (n = 15) for 4 days in increasing dosages (day 1: 6 g; day 2: 12 g; days 3 and 4: 18 g) or a mucolytic basis dosage of NAC (3 x 300 mg/day [control]; n = 15), respectively.

MEASUREMENTS AND MAIN RESULTS

Blood samples were taken before NAC high-dose infusion (day 1), after increasing doses of NAC (days 3 and 5) and 4 days after the last high-dose treatment (day 8). Neutrophil oxidative burst activity after stimulation with Escherichia coli and polymorphonuclear phagocytosis were determined in a flow cytometric assay. Baseline values of polymorphonuclear functions were comparable in both groups. NAC high-dose treatment resulted in a significantly improved phagocytosis activity compared with control patients. In contrast to this, polymorphonuclear burst activity was significantly reduced in the NAC high-dose treated group on day 3.

CONCLUSION

These findings suggest that infusion of NAC in high doses affects granulocyte functions in critically ill patients. Antimicrobial host defense requires the effective sequence of cell adhesion, phagocytosis, and bactericidal respiratory burst. The enhanced phagocytotic activity might be a compensatory mechanism in states of impaired respiratory burst to maintain tissue sterility. For certain mechanisms of disease, the effects observed might be favorable (e.g., ischemia/reperfusion, endothelial cell activation), for others (infection) this might be detrimental.

A model of bacterial translocation in neuroblastoma-bearing mice

PURPOSE

The aim of this study was to establish a model of bacterial translocation (BT) in neuroblastoma-bearing mice.

METHODS

A suspension of 1 x 10(6) cells of the murine neuroblastoma cell line C1300 was injected subcutaneously into the thighs of 8-week-old female A/J mice, which were then killed after 7, 14, and 21 days. Some of the mice were given 1-microm or 2-microm fluorescein-labeled latex beads in their drinking water for 7 days before being killed. Mesenteric lymph nodes (MLNs) were aseptically removed and cultured for 72 hours at 37 degrees C. Segments of distal ileum were obtained for histologic examination. Samples of venous blood were obtained for laboratory tests.

RESULTS

Tumors were found at the injection sites on days 14 and 21 after C1300 injection. Although tumors were not found in 7 days, significantly high number of 1-microm latex beads were detected in MLNs compared with the control, and the number increased with tumor growth. The number of 2-microm latex beads was significantly higher on days 14 and 21. The percentage of mice with MLN cultures positive were significantly higher on day 14, and the percentage increased along with tumor growth. On day 21 after C1300 injection, body weight loss and anemia were observed, and histologic findings of the terminal ileum showed mucosal edema and villous thinning. Serum levels of interleukin (IL)-6 were significantly higher in mice killed 14 and 21 days after injection.

CONCLUSIONS

The results suggest that BT from the gut to MLNs may occur in neuroblastoma C1300-bearing mice, and it increases along with tumor growth. Even in the early stage of malignancy, particles as small as 1 microm may translocate from the gut to MLNs.

Neutrophil depletion in rats reduces burn-injury induced intestinal bacterial translocation

OBJECTIVE

To determine whether neutrophil depletion could eradicate intestinal bacterial translocation in bum-injured rats.

DESIGN

Prospective, randomized, controlled study.

SETTING

University research laboratory.

SUBJECTS

Adult male Sprague-Dawley rats.

INTERVENTIONS

The rats were intravenously administered a rabbit anti-rat neutrophil antibody causing profound neutropenia and subjected to a 30% total body surface area scald burn.

MEASUREMENTS AND MAIN RESULTS

The depletion of neutrophils from the intestine was assessed via measurements of myeloperoxidase (MPO) activity in the intestinal homogenates. In addition, the presence of activated/extravasated neutrophils in intact intestines was determined via immunohistochemical localization of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase component protein p47phox. Bacterial translocation was measured using agar cultures and by determining Escherichia coli beta-galactosidase gene via polymerase chain reaction/Southern blot analyses of mesenteric lymph node and spleen, liver, lung, and blood. MPO measurements demonstrated a six-fold increase above the control value in the intestinal tissue in rats on day 1 postburn. The presence of activated neutrophils (expression of p47phox protein) was also markedly increased in the intestines of these rats. The increased MPO activity and p47phox expression accompanied a translocation of indigenous E. coli into the mesenteric lymph node without a spread to other organs. The administration of anti-neutrophil antibody to burn animals prevented an increase in MPO activity and bacterial translocation.

CONCLUSION

These studies indicate that enhanced intestinal bacterial translocation caused by burn injury could be related to the increased infiltration of activated neutrophils into the intestinal tissue after bum. The release of neutrophil products such as superoxide anion may effect intestinal tissue damage leading to bacterial translocation of indigenous E. coli.

Isolation of bacteria from cervical lymph nodes in patients with oral cancer

Thirty patients with oral mucosal cancer were studied in relation to oral mucosal damage and bacterial translocation to the regional lymph nodes in the neck. All 30 patients (gingiva 11, tongue 13, cheek mucosa four, oral floor two) underwent extensive, clean-contaminated, head-and-neck surgery (including neck dissection) with free flap reconstruction. A total of 153 lymph nodes was harvested for microbial and histological examination. Viable bacteria were isolated from 70 lymph nodes (45.8%) from 25 patients (83.3%). Bacterial cells in the nodes were detected by scanning electron microscopy. Bacterial translocation was found more often in metastatic nodes (75.0%) than in uninvolved nodes (40.3%) (p = 0.015; chi2 test). Gingival carcinoma yielded 56.4% of bacterial growth in the regional lymph nodes compared to tongue (40.3%), oral floor (40.0%) and cheek mucosa (37.5%). As the gingival carcinoma group includes more T4 cases (11/11; 100%) than the other three groups (7/19; 36.8%), bacterial translocation in uninvolved nodes could be caused by the size and invasion of the primary oral tumor. Oral streptococci (Streptococcus intermedius, Strep. constellatus, Strep. oralis, Strep. mitis, Strep. sanguis, Strep. salivarius) were the most common isolates. Aerobic enteric bacteria (Enterococcus, Escherichia, Klebsiella etc.) were also found in the lymph nodes. Among the anaerobic bacteria, Peptostreptococcus spp. were isolated from 12 patients. Damaged oral mucosa in patients with oral cancer might allow the new bacterial colonization on the surface and subsequently drain the bacteria into the regional lymph nodes as well as the general circulation.

Effects of intravenous anesthetics on bacterial elimination in human blood in vitro

BACKGROUND

Since anesthetics are widely used in critically ill patients, this study investigates anesthetic effects on neutrophil and monocyte function concerning bacterial elimination in human whole blood.

METHODS

The effects of thiopental (20 and 200 microg/ml), propofol (5 and 50 microg/ml), midazolam (0.15 and 1.5 microg/ml) and ketamine (3 and 30 microg/ml) on elimination of Escherichia (E.) coli from whole blood were investigated in vitro after incubation for 1 h in both clinical (1) (n=10) and 10-fold higher (h) (n=11) concentrations. These data were compared to neutrophil and monocyte phagocytosis (1; n=6) and burst activity (1; n=10, h; n=11), measured by flow cytometry. To enable quantification of the clearance process, a defined number of 10(5) colony forming units of E. coli were added to the blood assays and bacterial growth was determined.

RESULTS

All anesthetics delayed bacterial clearance from the blood in the 10-fold concentration (P<0.05). Thiopental (1+h) and propofol (h) suppressed neutrophil (59+/-3% and 38+/-6%) and monocytic (45+/-6% and 30+/-11%) oxidative burst (P<0.01). Phagocytosis was reduced even after propofol (1) in polymorphonuclear leukocytes (PMN) (34+/-9%; P<0.05) and monocytes (35+/-11%). Ketamine (h) prolonged bacterial elimination (P<0.01), which did correlate with inhibition of monocytic phagocytosis, by 26+/-14%. Midazolam application (h) resulted in an inhibition of PMN-respiratory burst by 19+/-6% (P<0.05) and impaired bacterial clearance (P<0.05).

CONCLUSION

Thiopental, propofol, midazolam and ketamine affect E. coli clearance and neutrophil and monocyte oxidative burst and phagocytosis in vitro only in high concentrations, while thiopental inhibited monocytic burst and propofol impaired PMN phagocytosis even in clinically used concentrations. These data suggest that i.v. anesthetics in concentrations recommended for general anesthesia seem to have minor influence on the investigated host defense mechanisms.

Peritonite aguda experimental em ratos: modelo de bloqueio transdiafragmático com membrana celulósica

O objetivo deste trabalho foi analisar o efeito do bloqueio transdiafragmático na vigência de peritonite aguda infecciosa induzida por inoculação de suspensão bacteriana qualitativa e quantitativa predeterminada. Foram analisados 41 ratos, adultos, machos, da raça Wistar, com peso variando de 118 a 399 g. Os animais foram alocados em dois grupos: grupo A ou controle (n=19), e grupo B ou experimental (n=22). Os animais do grupo B, após indução anestésica inalatória, foram submetidos a laparotomia e bloqueio da superfície peritoneal diafragmática com membrana celulósica e mantidos sob condições ad libitum por 15 dias.. Após esse período, em ambos os grupos inoculou-se, por via percutânea na cavidade abdominal, suspensão bacteriana constituída de Pseudomonas aeruginosa 2,7 x 10(9) UFC/ml (American Type Culture Collection - ATCC 25853), na proporção de 1 ml de suspensão para cada 100 g de peso. Sempre que se detectou o óbito, o animal foi submetido a necropsia para avaliação macroscópica da cavidade peritoneal e pleural, bem como coleta de conteúdo pleural e punção intracardíaca para cultura. Os animais sobreviventes foram sacrificados após 48 horas e, também, submetidos a necropsia e coleta de material para avaliação bacteriológica. Verificaram-se em todos os animais sinais clínicos característicos do estado séptico evolutivo. A incidência de derrame pleural observada no grupo controle em relação ao grupo experimental foi, respectivamente, 18 (94,7%) e oito (36,4%), (p=0,0001). Na análise bacteriológica do derrame pleural e na hemocultura de ambos os grupos, isolou-se como agente único Pseudomonas aeruginosa em, respectivamente, 88,46% e 60,97%. Para a análise da curva de sobrevivência utilizou-se o método não-paramétrico de Kaplan-Meier, demonstrando maior sobrevida no grupo B (p=0,024; p=0,0211). Demonstrou-se, no presente estudo, que os animais submetidos a bloqueio transdiafragmático prévio com membrana celulósica apresentaram maior sobrevida e menor freqüência de derrame pleural, estatisticamente significante, quando comparados aos animais não submetidos ao bloqueio.

The effects of vagotomy on bacterial translocation: an experimental study

The effects of truncal vagotomy and proximal gastric vagotomy on bacterial translocation in rats were investigated in this experiment. The rats were divided into three groups. Only esophageal and gastric manipulations were performed in the control group (Group I). The anterior and posterior vagi were found and 0.5- to 1-cm pieces were taken out in the truncal vagotomy + pyloric dilatation group. In addition, pyloric dilatation was performed using a Fogarty catheter (Group II). The branches of the vagi, which lead to the rumen and corpus, were first tied with 5/O silk and then resected in the proximal gastric vagotomy group (Group III). All animals were sacrificed on the 7th day. Qualitative and quantitative tissue cultures of cecum, liver, spleen, mesenteric lymph node, and blood from vena cava were taken and a tissue sample from the ileum was obtained for histopathological examination with light microscopy. At the end of microbiologic study, the bacterial concentration on the cecal wall was 10.68 x 10(8) in the truncal vagotomy group, while it was 0.53 x 10(8) in the proximal gastric vagotomy group. Bacterial translocation was observed more in vagotomy groups than in control groups on the mesenteric lymph node, liver, and spleen. Bacterial translocation was greater in the truncal vagotomy group than in the proximal gastric vagotomy group (P < 0.05). Bacterial translocation was observed mostly in the liver, spleen, and mesenteric lymph node in the proximal gastric vagotomy group. No microorganisms could be cultured on systemic blood cultures. Cultures were positive only for one rat in the proximal gastric vagotomy group and for two rats in the truncal vagotomy group. At the end of histopathologic examination, when histopathologic parameters given for each rat were calculated, they were 5.44 +/- 2.12 in the truncal vagotomy group and 4.77 +/- 2.12 the in proximal gastric vagotomy group. The difference between these two groups was statistically significant (P < 0.05). Thus, there was damage to the intestinal wall in vagotomy groups, and it was greater in the truncal vagotomy group than in the proximal gastric vagotomy group. It was observed that bacterial translocation occurs after vagotomy, that this translocation occurs more after truncal vagotomy than after proximal gastric vagotomy, and that the translocation that occurred after vagotomies was not effective enough to create bacteremia.

Glutamine supplementation in cancer patients receiving chemotherapy: a double-blind randomized study

The purpose of this study was to evaluate the efficacy of glutamine in preventing doxifluridine-induced diarrhea and the potential impact of glutamine on the tumor growth. We investigated 65 patients with advanced breast cancer receiving doxifluridine in a double-blind randomized fashion: 33 patients took glutamine (30 g/d, divided in 3 doses of 10 g each) for 8 consecutive days (5-12h) during each interval between chemotherapy, which was administered from day 1 to 4. Thirty-two patients took an equal dose of placebo (maltodextrine). The incidence of diarrhea was registered after each cycle of chemotherapy and severity was scored by the National Cancer Institute (NCI), Bethesda, Maryland, classification. The tumor response was evaluated by the World Health Organization (WHO) criteria. A total of 278 and 259 cycles (median 10 cycles), respectively, were delivered in glutamine and placebo groups. There were 34 and 32 episodes of diarrhea in glutamine and placebo groups, with no statistical difference overall, in the severity and duration of tumor growth, there was no difference in the response rate (21% and 28% of complete or partial response, respectively), in median time to response (2 mo), or in median duration of response. In conclusion, glutamine did not prevent the occurrence of the doxifluridine-induced diarrhea and did not have any impact on tumor response to chemotherapy.

Glutamine-supplemented tube feedings versus total parenteral nutrition in children receiving intensive chemotherapy

Although enteral nutrition is generally advocated in the care of children with cancer, those patients receiving intensive chemotherapy alone or in combination with bone marrow transplantation often require total parenteral nutrition (TPN). Two patients are presented illustrating some differences between enteral and parenteral feedings in children receiving intensive chemotherapy. Nasogastric glutamine-supplemented tube feedings were well tolerated both in the hospital and at home. The cost of care for the enterally supported child was less than one third of the TPN-supported child. Although TPN appears to be beneficial in some patients with cancer, it is expensive and is associated with several significant disadvantages. Among these are an increased incidence of both gram-positive and gram-negative infections and an increased incidence of gastrointestinal symptoms. Enteral nutrition is less costly than TPN and maintains the structural and functional integrity of the intestinal mucosa. The addition of certain substrates such as glutamine, arginine and omega-3 fatty acids may improve the body's immune response as well. We hypothesize that early glutamine supplemented tube feedings in children receiving intensive chemotherapy alone or in combination with bone marrow transplantation will result in improved nutrition with fewer infections and lower cost than TPN-supplemented patients. In addition, a shorter hospital stay and improved quality of life are anticipated.

Increased intestinal permeability in rats with graft versus host disease

BACKGROUND/AIMS

The study of graft versus host disease of the intestine has significant clinical relevance and may also be a model for other immune mediated intestinal diseases. There presently is no simple non-invasive test that can be used to evaluate graft versus host disease induced intestinal injury in humans or animal models. This study tested the hypothesis that graft versus host disease leads to an increase in host bowel permeability as assessed by the relative urinary excretion of orally administered lactulose and rhamnose.

METHODS

The urinary excretion ratio of orally administered lactulose and rhamnose was determined daily for two weeks in (Lewis x Brown-Norway) F1 rats with graft versus host disease caused by either the transplantation of parental (Lewis) small bowel or the intraperitoneal injection of parental (Lewis) splenic lymphocytes.

RESULTS

Significant twofold to fourfold increases in the lactulose to rhamnose ratio were seen in both small bowel transplant and splenic lymphocyte transfer animals suffering from graft versus host disease during the second postoperative week. This effect occurred sooner in small bowel transplant than in splenic lymphocyte transfer animals (postoperative day 7 versus 11, respectively). The signs of graft versus host disease, including splenomegaly and altered intestinal mucosal architecture, as well as the increased lactulose to rhamnose ratio were significantly attenuated in small bowel transplant animals treated with cyclosporine A (10 mg/kg/day).

CONCLUSIONS

Graft versus host disease is associated with an increase in the lactulose to rhamnose clearance ratio reflecting an increase in host bowel permeability. This increase, along with the signs of systemic graft versus host disease, can be significantly ameliorated by cyclosporine A. The lactulose to rhamnose clearance ratio is a non-invasive technique that can be used to assess the intestinal effects of graft versus host disease and the associated increase in intestinal permeability.

The protective role of enteral IgA supplementation in neonatal gut origin sepsis

Preterm infants and infants unable to breast feed are particularly susceptible to gut origin sepsis. Many studies have shown the benefits of breast milk in decreasing the incidence of bacterial infections in neonates. Little in vivo work has focused on prevention of neonatal gut origin sepsis with breast milk components. The aim of this study was to determine whether supplementation of a standard neonatal formula with exogenous, luminally administered, human secretory IgA protects against gut origin sepsis in a newborn rabbit model. Sixty New Zealand white rabbit pups were delivered by cesarean section 1 day preterm and divided into two groups--the IgA group (n = 26) and the non-IgA group (n = 34). Animals were gavage-fed a standard artificial formula (KMR) twice daily. The IgA group was supplemented on days 3 and 4 with 6.25 mg/kg of human secretory IgA. The non-IgA group received an equal volume of saline. On the evening of day 3, the animals were orally challenged with Escherichia coli K100. The quantity of bacteria that colonized the cecum was similar in the two groups. The quantity of bacteria that translocated to the mesenteric lymph node, liver, and spleen was significantly lower in the IgA group (P < .05). The incidence of translocation to the organs was also significantly lower in the IgA group (P < .05). The exogenous secretory IgA showed specificity to E coli K100 by ELISA. These data show that neonatal formula supplemented with human secretory IgA decreases the incidence and quantity of bacterial translocation of E coli K100 in a neonatal rabbit model.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of a water-soluble ethylhydroxyethyl cellulose on gut physiology, bacteriology, and bacterial translocation in acute liver failure

Bacterial infection and bacteremia are common complications in patients with acute liver failure. Bacterial translocation from the gut has been suggested to be a major cause of bacterial infections in experimental acute liver failure. In the present study, a water-soluble ethylhydroxyethyl cellulose (EHEC) was administered orally 1 and 24 hours prior to 90% hepatectomy in the rat in order to prevent bacterial translocation in experimental acute liver failure induced by subtotal liver resection in the rat. Ninety percent hepatectomy alone resulted in 80 to 100% translocation to mesenteric lymph nodes or blood 2 and 4 hours after operation. There was no translocation in rats undergoing sham operation or 90% hepatectomy with EHEC administration prior to operation (p < .01). Bacterial overgrowth, increased bacterial adherence onto the intestinal surface, and diminished intestinal and mucosal mass were also observed in animals with subtotal liver resection, but not in those administered EHEC. A delayed 2-hour intestinal transit time occurred in both groups receiving subtotal liver resection, with or without oral EHEC. EHEC inhibited bacterial growth and DNA synthesis and altered bacterial surface properties after 1-hour incubation with bacteria in vitro, an interaction that was not further influenced by time. These results imply that EHEC may alter enterobacterial capacities of metabolism, proliferation, and invasion by effects on the bacterial surface. Furthermore, EHEC seems to possess a trophic action on the intestine, though without enhancing the intestinal motility.

Glutamine and cancer

OBJECTIVE

This overview on glutamine and cancer discusses the importance of glutamine for tumor growth, summarizes the alterations in interorgan glutamine metabolism that develop in the tumor-bearing host, and reviews the potential benefits of glutamine nutrition in the patient with cancer.

SUMMARY BACKGROUND DATA

Glutamine is the most abundant amino acid in the blood and tissues. It is essential for tumor growth and marked changes in organ glutamine metabolism are characteristic of the host with cancer. Because host glutamine depletion has adverse effects, it is important to study the regulation of glutamine metabolism in cancer and to evaluate the impact of glutamine nutrition in the tumor-bearing state.

METHODS

Data from a variety of investigations on glutamine metabolism and nutrition related to the host with cancer were compiled and summarized.

RESULTS

Numerous studies on glutamine metabolism in cancer indicate that many tumors are avid glutamine consumers in vivo and in vitro. As a consequence of progressive tumor growth, host glutamine depletion develops and becomes a hallmark. This glutamine depletion occurs in part because the tumor behaves as a "glutamine trap" but also because of cytokine-mediated alterations in glutamine metabolism in host tissues. Animal and human studies that have investigated the use of glutamine-supplemented nutrition in the host with cancer suggest that pharmacologic doses of dietary glutamine may be beneficial.

CONCLUSIONS

Understanding the control of glutamine metabolism in the tumor-bearing host not only improves the knowledge of metabolic regulation in the patient with cancer but also will lead to improved nutritional support regimens targeted to benefit the host.

Alterations of bacterial clearance induced by endotoxin and tumor necrosis factor

The purpose of the study was to investigate the potential influence of endotoxin and tumor necrosis factor (TNF) on immune function in terms of systemic clearance and organ distribution of injected Escherichia coli in a rabbit model. To enable quantification of the clearance process, defined numbers of exogenous E. coli (1.3 x 10(8) CFU) were injected intravenously 60 min after bolus application of TNF (4 x 10(5) U, n = 6), after infusion of endotoxin (40 micrograms/kg of body weight) for 1 h (n = 6) or 4 h (n = 6), or after saline infusion (controls, n = 6). Parameters monitored were arterial pressure, oxygen uptake, and rates of bacterial elimination from the blood. At 180 min after E. coli injection, the animals were sacrificed, and tissue samples of liver, kidney, spleen, and lung were collected for bacterial counts. Endotoxin infusion produced a significant delay in blood clearance compared with saline and TNF pretreatment. The diminished systemic bacterial elimination was associated with significantly higher numbers of E. coli in the organs, thus reflecting reticuloendothelial system dysfunction. TNF had no major influence on the elimination kinetics of bacteria but affected the tissue distribution pattern with increased accumulation of E. coli in the lung (up to 100-fold of control values; P < 0.001).

Differential pathophysiology of bacterial translocation after thermal injury and sepsis

Bacterial translocation (BT) occurs transiently after thermal injury and may result from an ischemic intestinal insult. To evaluate continued intestinal ischemia in the ongoing BT associated with sepsis after injury, rats were randomized to (1) 30% burn injury with Pseudomonas wound infection (BI), (2) BI + fluid resuscitation (BI + Fluid), (3) BI after allopurinol pretreatment to inhibit xanthine oxidase (BI + Allo), or (4) BI after azapropazone pretreatment to inhibit neutrophil degranulation (BI + Aza). On postburn days (PBD) 1, 4, and 7, animals were studied for evidence of BT and intestinal lipid peroxidation. BI + Fluid, BI + Allo, and BI + Aza significantly (p less than 0.05) reduced rates of BT and ileal lipid peroxidation acutely after thermal injury (PBD 1) compared to BI. All four groups had equally high rates of BT associated with the onset of sepsis (PBDs 4 and 7), without evidence of further intestinal lipid peroxidation. These data indicate that the chronic gut barrier failure associated with sepsis after injury occurs independently of continued intestinal ischemia.

The analysis of the defense mechanism against indigenous bacterial translocation in X-irradiated mice

The defense mechanism against indigenous bacterial translocation was studied using a model of endogenous infection in X-irradiated mice. All mice irradiated with 9 Gy died from day 8 to day 15 after irradiation. The death of mice was observed in parallel with the appearance of bacteria from day 7 in various organs, and the causative agent was identified to be Escherichia coli, an indigenous bacterium translocating from the intestine. Decrease in the number of blood leukocytes, peritoneal cells and lymphocytes in Peyer's patches or mesenteric lymph nodes was observed as early as 1 day after irradiation with 6 or 9 Gy. The mitogenic response of lymphocytes from various lymphoid tissues was severely affected as well. The impairment of these parameters for host defense reached the peak 3 days after irradiation and there was no recovery. However, in vivo bactericidal activity of Kupffer cells in mice irradiated with 9 Gy was maintained in a normal level for a longer period. It was suggested that Kupffer cells play an important role in the defense against indigenous bacteria translocating from the intestine in mice.

Intestinal gram-negative bacterial overgrowth in vivo augments the in vitro response of Kupffer cells to endotoxin

A number of disease states and therapeutic maneuvers common to surgical patients can result in changes in the intestinal flora, permitting bacterial overgrowth and translocation of bacteria to gut lymphoid tissue. It is possible that these changes in gut flora increase portal levels of several factors that are capable of altering macrophage activation state, including endotoxin, lymphokines, and eicosanoids. Since Kupffer cells are directly exposed to gut factors via the portal circulation, changes in intestinal flora may influence Kupffer cell responses. Using germfree rats, it has previously been shown that the presence of gut bacterial flora is important in inducing Kupffer cells to respond to endotoxin, and that an overgrowth of gram-negative bacteria can further augment Kupffer cell responses, supporting the above-mentioned hypothesis. The current set of experiments examines how intestinal gram-negative bacterial overgrowth in normal adult rats effects the response of Kupffer cells to septic stimuli. Kupffer cells were obtained from conventional rats with induced intestinal overgrowth with Escherichia coli C25 for 2 or 7 days. After 2 days of overgrowth, Kupffer cells were only slightly less responsive to lipopolysaccharide (LPS) than control Kupffer cells. However, after 7 days of overgrowth, when placed in coculture with normal hepatocytes, Kupffer cells were significantly more responsive to LPS (p less than 0.001), inducing a greater degree of suppression in hepatocyte protein synthesis at lower LPS concentrations. When cultured alone, Kupffer cells from these animals also produced more interleukin-1 (p less than 0.002) and prostaglandin E2 (PGE2) (p less than 0.009) in response to LPS. These results show that intestinal gram-negative bacterial overgrowth in conventional rats can have direct influences on the response of hepatic macrophages to septic stimuli, and provides further support to the hypothesis that imbalances in the intestinal flora can effect the responses of immune cells in other sites of the body.

The role of intestinal flora on the interactions between nonparenchymal cells and hepatocytes in coculture

Kupffer cells are exposed directly to a number of factors in the portal circulation that can modify or regulate their responses to septic stimuli. The gut represents a potential source of a number of these factors including endotoxin, lymphokines, and prostaglandins. We examined Kupffer cells from germfree rats and germfree rats exposed to endotoxin or bacteria via their GI tracts to determine the importance of the intestinal flora in maintaining or modulating Kupffer cell responses. Kupffer cells from germfree animals were reduced in numbers and failed to respond to LPS in Kupffer cell: hepatocyte coculture. When germfree rats were exposed to bacterial endotoxin or bacteria via the gastrointestinal tract their Kupffer cells increased in numbers to normal and the cells responded to LPS in culture. Intestinal overgrowth with Escherichia coli for 2 days activated the Kupffer cells and significantly increased Kupffer cell sensitivity to LPS. These data suggest that the environment of the gastrointestinal tract is important for normal Kupffer cell responses and that intestinal bacterial overgrowth can modify Kupffer cell responses to septic stimuli.