Mesenteric Lymph Node Cultures Research Articles

Bacterial translocation up-regulates GTP-cyclohydrolase I in mesenteric vasculature of cirrhotic rats

In cirrhosis, arterial vasodilation and the associated hemodynamic disturbances are most prominent in the mesenteric circulation, and its severity has been linked to bacterial translocation (BT) and endotoxemia. Synthesis of nitric oxide (NO), the main vasodilator implicated, is dependent on the essential cofactor tetrahydrobiopterin (BH 4). The key enzyme involved in BH 4 synthesis is GTP-cyclohydrolase I (GTPCH-I), which is stimulated by endotoxin. Therefore, we investigated GTPCH-I activity and BH 4 biosynthesis in the mesenteric vasculature of cirrhotic rats with ascites, as well as their relationship with BT and endotoxemia, serum NO, and mean arterial pressure (MAP). GTPCH-I activity and BH 4 content in mesenteric vasculature was determined by high-performance liquid chromatography. BT was assessed by standard bacteriologic culture of mesenteric lymph nodes (MLNs). Serum endotoxin was measured by a kinetic turbidimetric limulus amebocyte lysate assay, and serum NO metabolite (NOx) concentrations were assessed by chemiluminescence. BT was associated with local lymphatic and systemic appearance of endotoxin and was accompanied by increases in serum NOx levels. GTPCH-I activity and BH 4 content in mesenteric vasculature were both increased in animals with BT and correlated significantly ( r = 0.69, P < .01). Both GTPCH-I activity and BH 4 levels significantly correlated with serum endotoxin and NOx levels ( r = 0.69 and 0.54, 0.81 and 0.53, P < .05). MAP (a marker of systemic vasodilatation) correlated with endotoxemia ( r = 0.58, P < .03) and with GTPCH-I activity ( r = 0.69, P < .01). In conclusion, in cirrhotic animals BT appears to lead to endotoxemia, stimulation of GTPCH-I, increased BH 4 synthesis, and further enhancement of vascular NO production that leads to aggravation of vasodilatation. (H epatology 2003;38:1508-1515.)

Bacterial translocation up-regulates GTP-cyclohydrolase I in mesenteric vasculature of cirrhotic rats.

In cirrhosis, arterial vasodilation and the associated hemodynamic disturbances are most prominent in the mesenteric circulation, and its severity has been linked to bacterial translocation (BT) and endotoxemia. Synthesis of nitric oxide (NO), the main vasodilator implicated, is dependent on the essential cofactor tetrahydrobiopterin (BH(4)). The key enzyme involved in BH(4) synthesis is GTP-cyclohydrolase I (GTPCH-I), which is stimulated by endotoxin. Therefore, we investigated GTPCH-I activity and BH(4) biosynthesis in the mesenteric vasculature of cirrhotic rats with ascites, as well as their relationship with BT and endotoxemia, serum NO, and mean arterial pressure (MAP). GTPCH-I activity and BH(4) content in mesenteric vasculature was determined by high-performance liquid chromatography. BT was assessed by standard bacteriologic culture of mesenteric lymph nodes (MLNs). Serum endotoxin was measured by a kinetic turbidimetric limulus amebocyte lysate assay, and serum NO metabolite (NOx) concentrations were assessed by chemiluminescence. BT was associated with local lymphatic and systemic appearance of endotoxin and was accompanied by increases in serum NOx levels. GTPCH-I activity and BH(4) content in mesenteric vasculature were both increased in animals with BT and correlated significantly (r = 0.69, P <.01). Both GTPCH-I activity and BH(4) levels significantly correlated with serum endotoxin and NOx levels (r = 0.69 and 0.54, 0.81 and 0.53, P <.05). MAP (a marker of systemic vasodilatation) correlated with endotoxemia (r = 0.58, P <.03) and with GTPCH-I activity (r = 0.69, P <.01). In conclusion, in cirrhotic animals BT appears to lead to endotoxemia, stimulation of GTPCH-I, increased BH(4) synthesis, and further enhancement of vascular NO production that leads to aggravation of vasodilatation.

Effects of alpha-tocopherol on bacterial translocation and lipid peroxidation in rats with intestinal obstruction

PURPOSE: Investigate if alpha-tocopherol has a protective effect on intestinal mucosa after obstruction and to evaluate the potential relations between lipid peroxidation and bacterial translocation. METHODS: Ten rats were submitted to a sham laparotomy and six served as control group. A small bowel obstruction was done in sixteen animals and among them eight were pretreated with alpha-tocopherol. Forty-eight hours later, mesenteric lymph node, spleen, liver and blood cultures and also samples from ileal mucosal were obtained, Thiobarbituric acid reactive substances (TBARS) levels were determined and intestinal histological assessment was performed. RESULTS: Bacterial translocation was significantly increased in the obstructed rats compared with the control, sham and antioxidant pretreated groups (p&lt; 0,05). TBARS (nmol/100mg) in untreated obstructed rats increased from 49,0 ± 13,3 in control group to 128,8 ± 40 after 48 hours of intestinal obstruction and achieved 72,3 ± 24,6 in alpha-tocopherol group (p&lt; 0,05). Bacterial adherence to the intestinal epithelial cells surface and mucosal necrosis were significantly increased in the obstructed compared with nonobstructed rats. CONCLUSION: Alpha-tocopherol reduce the deleterious effects of the TBARS over the intestinal mucosal suggesting that in such circumstances there might be an association between bacterial translocation and lipid peroxidation after an intestinal occlusion.

Spontaneous bacterial peritonitis associated with experimental cirrhosis: Comparative effect of different therapeutic options on endotoxinemia and hemodynamic derangement

OBJECTIVE: The aim of this investigation was to assess the role of different therapeutic options aimed at modifying the gut microecology in experimental liver cirrhosis in view of the cytokine cascade and splanchnic and systemic hemodynamics.METHODS: Cirrhosis was induced in male Sprague‐Dawley rats by carbon tetrachloride (CCL4). After the 6th week of CCL4 administration rats were divided into 5 groups for the remaining 6 weeks: (A) saline b.i.d; (B) lactulose 0.5 g b.i.d.; (C) rifaximine 1 mg b.i.d; (D) 2 mL b.i.d of a probiotic mixture and (E) 1 week of rifaximine followed by 5 weeks of probiotic.RESULTS: Rats with cirrhosis and ascites showed a significantly high concentration of either portal, splanchnic and systemic endotoxin, as well as plasma TNF‐α concentration (P &lt; 0.05). Rifaximine alone, rifaximine plus probiotic or probiotic alone significantly decreased the plasma endotoxin concentration at each of the three tested sites, as well as the plasma concentration of TNF‐α (P &lt; 0.01). Total Gram‐negative aerobic bacteria count in the stool markedly decreased together with a significant increase of the enterococcal population in the rifaximine plus probiotic group and, to a lesser extent, in the other treatment groups. Treated rats showed a significantly decreased occurrence of bacterial peritonitis and the rifaximine plus probiotic treatment was the most effective regimen. Each of the treatments significantly reduced the percentage of positive culture of either mesenteric lymph node or portal vein samples, rifaximine plus probiotic being the most effective. As compared with healthy control rats, those with cirrhosis showed a significantly lower mean arterial pressure and systemic vascular resistance, but a higher cardiac index and portal pressure. Spontaneous bacterial peritonitis further worsened the systemic vascular resistance, but this was partly improved by the rifaximine plus probiotic treatment.CONCLUSION: These data suggest that the association of a nonabsorbable antibiotic with a probiotic beneficially affects the abnormal systemic vasodilatory response in the course of severe liver cirrhosis, probably through the effects on endotoxin and indirect inhibition of TNF−α release.

Encapsulated Bifidobacterium bifidum potentiates intestinal IgA production

We asked whether Bifidobacterium bifidum regulates the synthesis of IgA by mucosal lymphoid cells. B. bifidum alone, but not Clostridium perfringens, significantly induced total IgA and IgM synthesis by both mesenteric lymph nodes (MLN) and Peyer’s patch (PP) cells. We, further, investigated the mucosal antibody production following peroral administration of B. bifidum to mice. Ingested B. bifidum significantly increased the number of Ig (IgM, IgG, and IgA) secreting cells in the culture of both MLN and spleen cells. Nonetheless, B. bifidum itself does not induce the own specific antibody responses, implying that B. bifidum does not provoke unnecessary immune reaction. Subsequently, it was found that encapsulation of B. bifidum further augments the total IgA production in the culture of both MLN and spleen cells. Finally, we found that the immuno-stimulating activity of B. bifidum is due to its cellular components but not due to any actively secreting component(s) from bacteria.

Heparin-binding EGF-like growth factor preserves crypt cell proliferation and decreases bacterial translocation after intestinal ischemia/reperfusion injury

Background/Purpose: Heparin-binding epidermal growth factor (EGF)–like growth factor (HB-EGF), a known mitogenic, chemotactic, and cytoprotective growth factor for epithelial cells, was examined to see whether it could protect intestinal barrier function and decrease bacterial translocation (BT) after ischemia/reperfusion (I/R) injury. Methods: In vitro, tight junctional integrity of intestinal epithelial cells (IEC-6) cells was evaluated by measuring transepithelial electric resistance (TEER), and monolayer permeability was evaluated by translocation of Escherichia coli C25. In vivo, crypt cell proliferation was assessed by 5-bromodeoxyuridine incorporation with calculation of a proliferative index (PI), and BT was evaluated by culture of mesenteric lymph nodes. Results: In vitro, anoxia damaged tight junctional integrity and increased permeability of IEC-6 cell monolayers, events that were reversed completely by treatment of the cells with HB-EGF. Twenty-four hours after I/R injury in vivo, crypt cell proliferation index (PI) decreased significantly from 35.6 ± 4.5 to 17.8 ± 3.4. Administration of HB-EGF preserved crypt cell activity with PI of 34.9 ± 4.1, similar to that of normal ileum. None of the normal or sham-operated animals showed BT, whereas BT occurred in 87.5% of I/R-injured rats. In animals exposed to I/R but treated with HB-EGF, BT was decreased significantly to 12.5%. Conclusion: HB-EGF preserves proliferation of crypt cells, maintains integrity of epithelial cells, and subsequently decreases enteric BT after I/R injury. J Pediatr Surg 37:1081-1087. Copyright 2002, Elsevier Science (USA). All rights reserved.

Probiotic supplementation reduces the risk of bacterial translocation in experimental short bowel syndrome

Background/Purpose: Probiotics are live organisms that survive passage through the gastrointestinal tract and have beneficial effects on the host. Lactobacillus and Bifidobacterium have been recommended for cholesterol lowering, acute diarrhea, prevention of cancer, or inflammatory bowel disease. On the other hand, after massive bowel resection, bacterial overgrowth is frequent and favors bacterial translocation (BT). The possible beneficial effects of Bifidobacterium lactis (BL) administration on BT in experimental short bowel syndrome (SBS), have not been investigated. The aim of this study was to test the hypothesis that BL administration decreases BT in SBS in animals fed orally. Methods: One hundred twenty-eight adult Wistar rats fed orally with standard rat chow and tap water “ad libitum” were maintained in individual metabolic cages for 10 days and divided into 3 groups: control group (n = 71): nonmanipulated animals; RES group (n = 39): 80% gut resection from 10 cm beyond the angle of Treitz to 10 cm above the cecum; RES-PRO group (n = 18): same resection and daily 7.8 × 108 CFU B Lactis administration, after orogastric intubation. At the end of the experiment they were killed, and mesenteric lymph nodes (MLN) and peripheral and portal blood specimens were recovered and cultured. Bacterial identification in blood was made by conventional methods, and MLN culture was considered positive with a growth over 100 CFU/g. Results: Bacterial translocation was detected in 6% of control group rats. The incidence of BT in the RES group was 87% (34 of 39), whereas only 50% (9 of 18) of RES-PRO animals had BT (P <.05). The relative risk reduction (RRR) was 0.43 (95% Cl 0.14 to 0.72), and the number needed to treat (NNT) was 3 (95% Cl 2 to 8). In other words, animals that received BL had the risk of BT reduced by 43% (RRR of 0.43), and of every 3 animals treated, 1 is expected to be free of BT (NNT of 3). Conclusion: Administration of B Lactis reduces the incidence of BT in adult Wistar rats after 80% gut resection. J Pediatr Surg 37:699-702. Copyright 2002, Elsevier Science (USA). All rights reserved.

Oral glutamine does not prevent bacterial translocation in rats subjected to intestinal obstruction and Escherichia coli challenge but reduces systemic bacteria spread

Objective: We investigated whether oral glutamine prevents bacterial translocation. Methods: Male Wistar rats were fed with isocaloric and isoproteic standard rat chow and randomly assigned to receive glutamine (GLN) or glycine administered through an orogastric tube at 1.5 g · kg −1 · d −1 for 7 d. On day 8 of the study, the animals were anesthetized and intestinal obstruction was produced by ligature of the terminal ileum. A suspension containing 10 9 colony-forming units per milliliter of Escherichia coli ATCC 25992 was injected into the lumen of the ileum. Twenty-four hours later, blood was withdrawn, and mesenteric lymph nodes and fragments of spleen, liver, and lung were sent for microbiological analysis. Cultures were done on blood agar and MacConkey agar. Student’s t test and analysis of variance between two proportions were used. P < 0.05 was considered significant. Results: Rats in both groups lost body weight during the experiment (not significant). Mesenteric lymph node cultures were positive in both groups. The GLN group had a smaller percentage of E. coli in blood and organ cultures (65.45% versus 82.67% in the glycine group; P = 0.027). Positive cultures of blood, spleen, liver and lung also were higher on glycine group, although not significantly. Conclusions: Oral GLN does not prevent bacterial translocation in rats after intestinal obstruction and E. coli challenge. No specific organ was protected by GLN. Nevertheless, its use was associated with a reduced number of positive E. coli cultures in blood and remote organs, and thus diminished bacteria spread. This association suggests a role for GLN in gut barrier protection, possibly by immune system enhancement.

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 × 106 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-μm or 2-μm 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°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-μm latex beads were detected in MLNs compared with the control, and the number increased with tumor growth. The number of 2-μm 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 μm may translocate from the gut to MLNs. J Pediatr Surg 35:1701-1705. Copyright © 2000 by W.B. Saunders Company.

Whole gut washout ameliorates the progression of acute experimental pancreatitis

Background: Septic complications are mainly responsible for deterioration of a patient with acute pancreatitis. Intestinal tract is accepted as the main source of pancreatic or peripancreatic infection. Material andmethods: Acute pancreatitis was induced in 40 Sprague-Dawley rats by ligation of the main biliopancreatic duct. Animals were divided into two groups. The first group of animals (n = 20) received high volume polyethylene glycol-3500 (GoLYTELY) for 6 hours through a silastic catheter introduced into the proximal part of the jejunum from a puncture gastrostomy during the initial laparotomy. The second group animals (n = 20) did not receive any treatment. Half of the animals from each group were sacrificed 72 hours later and tissue samples were taken from mesenteric lymph nodes, pancreas, spleen, and liver for bacteriologic cultures. Cecum cultures were also prepared. Blood samples at 72 hours were obtained for the measurement of amylase, lactic dehydrogenase (LDH), lactic acid, alanine aminotransferase (ALT), glucose, calcium, arterial pH, base excess, partial oxygen pressure, bicarbonate, leucocyte count, and hematocrit levels. The pancreas was examined histopathologically. The remaining half of the animals from each group were allowed to survive until death. Results: The levels of amylase, LDH, ALT, lactic acid, pH, pO 2, bicarbonate and base excess for the rats in group I were significantly lower when compared with the rats in group II ( P <0.05). Positive mesenteric lymph node cultures were detected in 30% of group I animals whereas they were positive in 90% of group II animals ( P = 0.0198). Distant organ cultures were positive in 8 animals (liver 5, spleen 2, pancreas 1) in group II, whereas only one positive distant organ culture (liver) was established in group I ( P >0.05). Histopathological scoring observed in the pancreas were less severe for the rats in group I when compared with the rats in group II ( P = 0.012). The rats in group I survived longer than the rats in group II (median survival 6.8 days versus 17.3 days, P <0.001). Conclusions: Whole gut washout with high-volume polyethylene glycol in pancreatitis reduced the blood levels of enzymes and increased the survival. Whole gut washout for acute pancreatitis appears effective to ameliorate the prognostic factors in blood and this modality may be a promising treatment method in acute pancreatitis.

The Prophylactic and Therapeutic Effects of Glutamine- and Arginine-Enriched Diets on Radiation-Induced Enteritis in Rats

Background. Recent studies indicated that glutamine and arginine support the mucosal barrier in several ways. This experimental study hypothesized that administration of glutamine- and arginine-enriched diets before abdominal radiation therapy would provide a radioprotective effect on intestinal mucosa, and this would augment the therapeutic effectiveness provided by postirradiation administration.Materials and methods. A rat model of radiation enteritis was designed with a single dose of 1100 cGy to the abdomen. Thirty-five rats were randomized into five groups of seven. A 7-day glutamine-enriched diet for Group I and a 7-day arginine-enriched diet for Group II were administered both pre- and postradiation. For Groups III and IV, the same glutamine and arginine diets were given, respectively, postradiation only. Group V was fed a glutamine- and arginine-free diet and was the control group. The rats underwent laparotomy for culture of mesenteric lymph nodes and removal of segments of ileum, jejenum, and colon for microscopic examination.Results. Bacterial translocation was significantly higher in Group V (P < 0.05), while intestinal villus count and villus height were significantly higher in all of the groups fed glutamine and arginine when compared with the control group (P < 0.0001 and P < 0.05, respectively).Conclusion. Both arginine- and glutamine-enriched diets have protective effects on gut mucosa in the postirradiation state; however, pre- and postirradiation administration together does not provide superior protection versus postradiation administration alone.

The effect of interleukin-6 on bacterial translocation in acute canine pancreatitis.

Bacterial translocation from the gut to mesenteric lymph nodes and other extraintestinal sites is an important source of infection in acute pancreatitis. Impaired host immunity is known to promote bacterial translocation. Interleukin-6 (IL-6) is a multifunctional cytokine that regulates the immune response, acute phase reaction, and hematopoiesis. Twenty-four mongrel dogs (18-29 kg) were studied in four equal groups. In Groups I and II, acute pancreatitis was induced by direct pressure injection of 4% taurocholate and trypsin into the pancreatic duct at laparotomy. Groups III and IV had only laparotomy. Group I and III dogs were given IL-6 (50 microg/kg/d, sq) daily starting 24 h after operation and Group II and IV dogs received an equal volume of saline administered at similar time. All animals had blood drawn for culture, complete blood count (CBC), platelets, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and amylase on d 0, 1, 4, and 7. On d 7, mesenteric lymph nodes (MLN), spleen, liver, pancreas, and cecum were harvested for pathology study and for cultures of aerobic and anaerobic bacteria. Quantitative cecal cultures of aerobic and anaerobic bacteria were obtained. All Group I and Group II dogs had severe pancreatitis. The increase of plasma CRP in Group I was sustained throughout treatment (1.3+/-0.3 on d 0 vs 3.1+/-0.3*, 3.0+/-0.3*, and 2.9+/-0.3* on d 1,4, and 7, respectively). Plasma CRP was increased in Group II on d 1 and d 4 (1.3+/-0.3 mg/dL on d 0 vs 3.6+/-0.3* mg/dL on d 1, and 3.1+/-0.3* on d 4, *p < 0.05). There were no differences in white blood cell (WBC) count, differential, platelets, and ESR between Groups I and II. Bacterial translocation to MLN was lower in Group I (1/6) than in Group II (6/6) (p < 0.05). All 6 dogs in Group II had bacterial spread to distant sites compared to 2 of 6 dogs in Group I (p = 0.066). Both MLN and other distant organ cultures were negative in Group III and only 1 of 6 MLN cultures was positive in Group IV. IL-6 treatment decreases bacterial translocation to MLN and may be beneficial in reducing septic complications in acute pancreatitis.

Small amount of low-residue diet with parenteral nutrition can prevent decreases in intestinal mucosal integrity.

To investigate the suitable combination ratio of low-residue diet (LRD) and parenteral nutrition (PN) for nutritional support of surgical patients. Bacterial translocation (BT) is a severe complication of total parenteral nutrition (TPN). However, it is sometimes impossible to supply sufficient amounts of nutrients to surgical patients by the enteral route. The authors reported previously that concomitant use of LRD with PN provided preferable nutritional support for patients undergoing surgery for colorectal cancer. Ninety male Donryu rats were used for three experiments. In experiment 1, rats were divided into two groups to receive TPN or total enteral nutrition with LRD. In experiment 2, rats were divided into six groups, receiving variable amounts of LRD. In experiment 3, rats were divided into five groups to receive isocaloric nutritional support with variable proportions of PN and LRD. Intestinal permeability was assessed by monitoring urinary excretion of phenolsulfonphthalein. BT was assessed in tissue cultures of mesenteric lymph nodes and spleen. In experiment 1, increases in intestinal permeability and BT were observed in rats maintained on 7-day TPN, but not in those maintained on total enteral nutrition for up to 14 days. In experiment 2, the changes in body weight of rats were correlated with the dose of LRD. However, the intestinal permeability was increased only in rats receiving LRD at 15 kcal/kg per day. In experiment 3, additive LRD corresponding to 15% of total caloric intake prevented increases in intestinal permeability and BT. Combined nutritional therapy consisting of PN and small amounts of LRD can provide better nutritional support than TPN for surgical patients.

Bacterial dissemination, rather than translocation, mediates hypermetabolic response in endotoxemic rats.

To study the pathogenesis of the host response during bacterial translocation, a rat model was designed for prolonged follow-up after injury. A prospective, controlled animal study. Animal laboratory. Young male Wistar rats. Antibiotic decontamination of rats was performed 4 days before intragastric inoculation with a selected Escherichia coli strain (10(10) bacteria/kg of body weight). Two days later, the rats received a lipopolysaccharide injection or not (control group) and were observed for 3 days. They were then killed. A reference group (pair-fed healthy animals) was studied in parallel. During observations, urinary total nitrogen loss and 3-methylhistidine excretion were determined daily. When the rats were killed, mesenteric lymph nodes (MLNs), spleen, and liver were aseptically removed and cultured. Colonies identified as translocated E. coli were counted in each organ. Intracellular amino acid free pools were measured in extensor digitorum longus and anterior tibialis. Endotoxin induces bacterial translocation of bacteria from gut lumen to MLNs (100% vs. 59% in the lipopolysaccharide-untreated control group; p < .05) and dissemination to spleen and liver (65% and 45% of positive cultures after endotoxemia, respectively, vs. 6% and 12% in the control groups). No translocation occurred in the reference group. Evidence for the hypermetabolic response was seen in lipopolysaccharide-treated and infected rats, but protein catabolism was more closely related to the occurrence of bacterial dissemination to spleen and liver than to translocation alone (e.g., the cumulative 3-methylhistidine excretion during the observation period was 4.07+/-0.18 micromol in uninfected rats, 4.48+/-0.29 in rats with positive MLN cultures alone and 6.17+/-0.30 in MLN, spleen, or liver infected rats; 1 vs. 2, NS; 3 vs. 1, and 3 vs. 2, p < .05). Gut barrier failure is associated with a deep excessive catabolic response in the host. The mechanism by which the metabolic state affects the resistance to infection apparently involves amino acid metabolism.

Schistosome-Infected IL-4 Receptor Knockout (KO) Mice, in Contrast to IL-4 KO Mice, Fail to Develop Granulomatous Pathology While Maintaining the Same Lymphokine Expression Profile

Th2 lymphocytes have been postulated to play a major role in the immunopathology induced by Schistosoma mansoni infection. Nevertheless, infected IL-4 knockout (KO) and wild-type (wt) mice develop egg granulomas comparable in size. To further investigate the function of the Th2 response in egg pathology we studied IL-4Ralpha-deficient mice, which are nonresponsive to both IL-4 and IL-13. In striking contrast to IL-4 KO animals, infected IL-4Ralpha KO mice developed only minimal hepatic granulomas and fibrosis despite the presence of CD3+ T cells in the residual egg lesions. Moreover, liver lymphokine mRNA levels in these animals and IL-4 KO mice were equivalent. In addition, infected IL-4Ralpha-deficient, IL-4-deficient, and wt animals developed similar egg Ag-specific IgG Ab titers, arguing that CD4-dependent Th activity is intact in KO mice. As expected, IFN-gamma secretion was strongly up-regulated in mesenteric lymph node cultures from both groups of deficient animals, a change reflected in increased serum IgG2a and IgG2b Ab levels. Surprisingly, Th2 cytokine production in infected IL-4Ralpha KO mice was not abolished but was only reduced and resembled that previously documented in IL-4 KO animals. This residual Th2 response is likely to explain the ability of IL-4 KO mice to generate egg granulomas, which cannot be formed in IL-4Ralpha-deficient animals because of their lack of responsiveness to the same cytokine ligands. Taken together, these findings argue that tissue pathology in schistosomiasis requires, in addition to egg-specific CD4+ lymphocytes, a previously unrecognized IL-4Ralpha+ non-T cell effector population.

Enteral nutrition prevents bacterial translocation but does not improve survival during acute pancreatitis.

To evaluate the effect of enteral nutrition (EN) in attenuating bacterial and/or endotoxin translocation, maintaining immune responsiveness, and improving outcome in early acute pancreatitis (AP) in Wistar male rats. Acute pancreatitis was induced in rats receiving total parenteral nutrition (TPN) (AP/TPN group) (n=34) and EN (AP/EN group) (n=35) by pressure injection of 1% deoxycholate into the biliopancreatic duct (0.6 mg/kg of body weight). Rats in the sham/TPN and sham/EN groups (n=10 each) underwent laparotomy without induction of AP. Catheters for TPN and EN were placed into the external jugular vein and jejunum, respectively. Rats were infused with Ringer lactate solution for 48 hours followed by TPN in the AP/TPN and sham/TPN groups, and EN in the AP/EN and sham/EN groups until day 7. The fluid volume and energy (calories) intake were similar in all groups. Medical school research laboratory. Survival, blood endotoxin level, villus height, 5-bromo-2'-deoxyuridine (BrdU) uptake in the jejunum and ileum, bacterial culture of mesenteric lymph nodes, and CD4/CD8 ratio of T cells in mesenteric lymph nodes, spleen, and peripheral blood. There was no difference in survival and pancreatic healing between the AP/TPN and AP/EN groups. Colony-forming units of the mesenteric lymph nodes and the endotoxin level were significantly lower in the AP/EN group than in the AP/TPN group (P<.05). Villus height and BrdU intake was significantly higher in the AP/EN group than in the AP/TPN group (P<.05). The CD4/CD8 ratio of T cells in spleen and peripheral blood was higher in the AP/EN group than in the AP/TPN group (P<.05), whereas there was no difference in mesenteric lymph nodes. Jejunal administration of EN is well tolerated in early AP, maintains immune responsiveness and gut integrity, and reduces bacterial and/or endotoxin translocation. However, compared with TPN, EN does not improve outcome. These results suggest that factors other than bacterial and/or endotoxin translocation may be responsible for mortality in this rat model of early AP. However, additional studies of both early bacterial and/or endotoxin translocation and late assessment of outcome are indicated.

The effect of sennosides on bacterial translocation and survival in a model of acute hemorrhagic pancreatitis.

Bacterial translocation leading to subsequent infectious complications is a significant determinant of outcome in acute hemorrhagic pancreatitis (AHP). The colonic ileus and impaired intestinal barrier function that often accompany AHP may predispose to translocation. Sennoside is a naturally occurring cathartic and choleretic agent that stimulates intestinal mucous secretion and has potent promotility effects. The impact of sennoside-induced intestinal motility and secretory function on bacterial translocation and survival was studied in a rat model of AHP. Severe acute pancreatitis was induced in rats by the intraductal infusion of 2% sodium deoxycholate (DCA, 0.4 ml/kg). A group of sham-operated rats (group A) received intraductal saline, whereas experimental animals were subsequently administered distilled water (group B) or sennoside solution (group C) by gavage every 8 h. After 48 h, intestinal transit of fluorescein isothiocyanate-labeled dextran, serum endotoxin, and amylase levels, and bacterial translocation to mesenteric lymph nodes (MLNs) and pancreatic tissue were determined. The pancreas and intestine were sampled for histologic study. All group A animals survived and did not develop pancreatitis or endotoxemia, whereas groups B and C all demonstrated severe hemorrhagic pancreatitis with evidence of necrosis. Mortality at 48 h was 55% in group B versus 12.5% in group C. Inhibition of intestinal motility was noted in 40% versus 20%, and endotoxin levels were 61.36+/-28.26 pg/L versus 5.41+/-3.58 pg/L in group B versus group C rats, respectively (p<0.001). Pancreatic tissue and MLN cultures were positive in 100% of group B survivors versus 14% of group C survivors (p<0.05). Histologic examination of the intestine in group C animals showed increased mucous secretion, proliferation of goblet cells, and evidence of rapid turnover/renewal of enterocytes. Treatment with the cathartic agent, sennoside, reduced translocation of endotoxin and bacteria, restored intestinal motility, increased mucous secretion, and reduced mortality in a model of acute hemorrhagic pancreatitis in the rat. Other cathartics may have similar properties and may be useful in preventing infectious complications in acute pancreatitis.

Effect of Alcohol on Bacterial Translocation in Rats

Bacterial translocation has been proposed to be important in the pathophysiology of sepsis, as well as to be a consequence of sepsis. To study the effect of alcohol on bacterial translocation from the gut, normal Sprague-Dawley rats were administered alcohol by gavage by two regimens: Acute (3.7 g/kg, one dose) or Subacute (1 of 2 doses, 2.4 or 3.7 g/kg/day once daily for 14 days). Mesenteric lymph node cultures were performed, and portal venous blood was assayed for endotoxin. Ileal and cecal permeability studies were performed in the Acute and Subacute groups using fluorescein isothiocyanate-labeled dextrans of either 4,000 or 70,000 kDa size. As an index of the effect of systemic endotoxin, tissues from mesenteric lymph nodes, liver, and intestinal Peyer's patches were assayed for the presence of mRNA for tumor necrosis factor. Additionally, because extrapulmonary sepsis has been shown to suppress pulmonary antibacterial defenses, animals in the Subacute group were challenged by aerosol inoculation with Pseudomonas aeruginosa to determine bacterial clearance and alveolar cellular responses. The results show that neither of the alcohol regimens resulted in bacterial growth from mesenteric lymph nodes or portal blood. Animals in the Subacute group had more endotoxin present in portal blood than did the Control group (92.9 pg/ml vs. 40.2 pg/ml; p < 0.02). None of the animals had demonstrable mRNA for tumor necrosis factor in any of the tissues assayed. There were no demonstrable increases in ileal or cecal permeability for either the small or large molecular weight dextran in either alcohol group. Furthermore, there was no delay in the clearance of P. aeruginosa from the lung in the Subacute group, but these animals recruited fewer neutrophils into the airspaces in response to this challenge than did the Control animals. Thus, alcohol intoxication does not result in bacterial translocation from the gut in this model. Despite higher levels of portal venous endotoxin in the animals in the Subacute alcohol group, no adverse systemic consequences of this phenomenon could be demonstrated.

Does large-bowel enema reduce septic complications in acute pancreatitis?

BACKGROUND: The source of septic complications in acute pancreatitis was unknown until recent years. The pathogenesis of bacterial translocation from the gut has been accepted as the main source of pancreatic or peripancreatic infection. This study was designed to investigate the role of large bowel enema during acute pancreatitis in preventing bacterial translocation. MATERIALS AND METHODS: Twenty-four Spraque-Dawley rats were used in this study. The rats were divided into two groups. Group I animals received biliopancreatic duct ligation plus colon cleansing by rectal enemas; group II animals received only biliopancreatic duct ligation. Rectal enemas were applied to the first group of animals three times, at 6, 24, and 48 hours after the operation using 10 cc sodium hydrogen phosphate solutions. All animals were sacrificed 72 hours later, and tissue samples were taken from mesenteric lymph nodes, pancreas, spleen, and liver for bacteriologic cultures via a midline laparatomy. Blood and cecum cultures were also prepared. RESULTS: Positive mesenteric lymph node cultures were found in all 12 animals in group II but in only 3 of 11 animals of group I ( P <0.05). Distant organ cultures were positive in 9 of group II, but the only infected distant organ culture found in group I was the positive liver culture ( P <0.05). CONCLUSION: As a result of this study, we believe that large bowel enema can reduce the frequency of septic complications in acute pancreatitis by reducing bacterial translocation.

Effects of Growth Hormone and Insulin-Like Growth Factor-I on Radiation Enteritis

The effect of growth hormone (GH) and insulin-like growth factor-I (IGF-I) on intestinal mucosal integrity and bacterial translocation after abdominal radiation was studied in rats. Animals were divided into the following groups: I (control), II (radiation), III (radiation plus GH) and IV (radiation plus IGF-I). Radiation (1,100 cGy) was administered on the 1st day to groups II, III and IV. GH [0.25 mg/kg body weight (BW) s.c. once daily] was administered on days 1, 2 and 3 to group III, and IGF-I (0.1 mg/kg BW s.c. twice daily) was given on days 1, 2 and 3 to group IV. On day 4, animals were sacrificed. Cultures of the mesenteric lymph nodes (MLN) and blood cultures from aorta and portal vein were performed. The number of villi per centimeter (V/cm), the villus height (Vh), mitoses per crypt (M/C) and protein and DNA contents of the mucosa were evaluated in samples from the terminal ileum. Radiation increased the number of positive MLN cultures, while treatment with GH and IGF-I reduced them significantly. V/cm, Vh, M/C, protein and DNA contents were significantly increased in all irradiated animals treated with GH and IGF-I. In conclusion both GH and IGF-I are not only capable of improving the mucosal integrity but also to reduce the bacterial translocation that follows intestinal radiation. In small doses IGF-I could reproduce the effects of GH and in some parameters the effects were more pronounced, although not statistically significant. This suggests that the effects of GH on intestine could be mediated through the local and systemic generation of IGF-I.