Effect of cisapride on intestinal bacterial and endotoxin translocation in cirrhosis

AIM: To investigate the effects of cisapride on intestinal bacterial overgrowth (IBO), bacterial and endotoxin translocation, intestinal transit and permeability in cirrhotic rats. METHODS: All animals were assessed with variables including bacterial and endotoxin translocation, intestinal bacterial overgrowth, intestinal transit and permeability. Bacterial translocation (BT) was assessed by bacterial culture of MLN, liver and spleen, IBO by a jejunal bacterial count of the specific organism, intestinal permeability by determination of the 24-hour urinary (99m)Tc-DTPA excretion and intestinal transit by measurement of the distribution of (51)Cr in the intestine. RESULTS: Bacterial translocation (BT) and IBO was found in 48 % and 80 % cirrhotic rats respectively and none in control rats. Urinary excretion of (99m)Tc-DTPA in cirrhotic rats with BT (22.2+/-7.8) was greater than these without BT (10.5+/-2.9). Intestinal transit (geometric center ratio) was significantly delayed in cirrhotic rats (0.31+/-0.06) and further more delayed in cirrhotic rats with BT (0.24+/-0.06) than these without BT (0.38+/-0.11). Cirrhotic rats with IBO had significantly higher rates of intestinal bacterial and endotoxin translocation, slower intestinal transit time and higher intestinal permeability than those without IBO. It was also found that BT was closely associated with IBO and the injury of intestinal barrier. Compared with the placebo group, cisapride-treated rats had lower rates of bacterial/endotoxin translocation and IBO, which was closely associated with increased intestinal transit and improved intestinal permeability by cisapride. CONCLUSION: These results indicate that endotoxin and bacterial translocation in cirrhotic rats may be attributed to IBO and increased intestinal permeability. Cisapride that accelerates intestinal transit and improve intestinal permeability might be helpful in preventing intestinal bacterial and endotoxin translocation.     

西沙比利对肝硬化大鼠小肠细菌及内毒素转位的影响

目的：研究西沙比利对肝硬化大鼠小肠细菌过度生长(IBO)，细菌及内毒素转位，小肠转运时间及小肠通透性的作用。方法：正常对照组大鼠25只，肝硬化对照组大鼠25只，肝硬化治疗组20只(用等渗盐水)，另20只肝硬化大鼠用西沙比利治疗，动物均测定各种参数如细菌和内毒素转位，小肠细菌过度生长，小肠转运时间及通透性。结果：48％肝硬化大鼠发生细菌转位，与无IBO肝硬化大鼠比较，IBO肝硬化大鼠的内毒素和细菌转位发生率高，肠转远时间延长，小肠通透性增高。BT的细菌与IBO主菌群一致。与对照组比较，西沙比利处理的肝硬化大鼠肠细菌和内毒素转位及IBO发生率降低，这与肠转运时间增快及通透性降低密切相关。结论：肝硬化大鼠内毒素和细菌转位可能是由于IBO和肠通透性增加的结果，而IBO的发生可能是由于肠转运时间延长所致。西沙比利可加速小肠转运时间，改善小肠通透性，这有助于防治小肠细菌和内毒素转位。     

Intestinal bacterial overgrowth and bacterial translocation in cirrhotic rats with ascites

Background/Aims: Translocation of indigenous bacterial from the gut lumen of cirrhotic animals to mesenteric lymph nodes appears to be an important step in the pathogenesis of spontaneous bacterial peritonitis. However, the sequence of events leading to translocation remains unclear. One of the most predictable risk factors for translocation is overgrowth of gut bacterial flora. The present study was designed to compare the intestinal aerobic bacterial flora of cecal stools at the time of sacrifice between cirrhotic and normal rats and to evaluate the role of intestinal aerobic bacterial overgrowth in bacterial translocation in cirrhotic rats.Methods: Thirty-five male Sprague-Dawley rats with carbon tetrachloride-induced cirrhosis and ascites and 10 normal rats were included in this study. Cirrhotic rats were sacrificed when ill and samples of ascitic fluid, mesenteric lymph nodes and cecal stool were taken for detecting quantitatively aerobic bacteria.Results: Total intestinal aerobic bacterial count in cecal stool at the time of sacrifice was significantly increased in cirrhotic rats with bacterial translocation with or without spontaneous bacterial peritonitis compared to cirrhotic rats without bacterial translocation (p<0.001 and p<0.001, respectively) and to normal rats (p<0.001 and p<0.001, respectively). Of the 42 species of bacteria translocating to the mesenteric lymph nodes, 41 (97.6%) were found in supranormal numbers in the stool at the time of sacrifice.Conclusions: Carbon tetrachloride-induced cirrhotic rats with bacterial translocation have increased total intestinal aerobic bacteria count, and intestinal bacterial overgrowth appears to play an important role in bacterial translocation in this experimental model of cirrhosis in rats.     

Effect of cisapride on intestinal bacterial overgrowth and bacterial translocation in cirrhosis

Deranged intestinal motility, which occurs in cirrhosis, may facilitate the development of intestinal bacterial overgrowth (IBO), which can lead to bacterial translocation (BT). To assess the effect of cisapride on IBO and BT in cirrhosis, cirrhotic rats received cisapride or a placebo for 7 days, and measurements of jejunal bacterial content and BT studies were performed. In addition, jejunal fluid from 46 cirrhotic patients was obtained for quantitative bacterial culture. Those patients in whom gram-negative IBO was detected were randomized to receive or not to receive cisapride (20 mg twice per day) for 1 week. Cisapride significantly reduced IBO in cirrhotic rats. In addition, no BT was documented in treated animals, whereas it occurred in 40% in nontreated cirrhotic rats. Total IBO was documented in 23 of 46 cirrhotic patients, which was caused by gram-negative organisms in 10 cases. Orocecal transit time (OCT) significantly decreased after cisapride therapy, and was associated with the abolishment of bacterial overgrowth caused by gram-negative organisms in 4 out of 5 treated patients, whereas it persisted in nontreated cases. Cisapride administration to cirrhotic rats resulted in a reduction of the IBO, which is associated with a marked decrease in BT. On the other hand, cisapride facilitates the abolition of IBO caused by gram-negative organisms in cirrhotic patients.     

Effect of propranolol on the factors promoting bacterial translocation in cirrhotic rats with ascites

Bacterial translocation appears to be an important mechanism in the pathogenesis of spontaneous infections in cirrhosis. Cirrhotic patients are commonly treated with beta-adrenoceptor blockers, but the impact of this treatment in the factors promoting bacterial translocation has not been investigated. This study was aimed at investigating in cirrhotic rats with ascites the effect of propranolol on intestinal bacterial load, transit, and permeability of the bowel and on the rate of bacterial translocation. Bacterial translocation to mesenteric lymph nodes and intestinal bacterial overgrowth, permeability (urinary excretion of (99m)Tc-diethylenetriaminepentaacetic acid [(99m)Tc-DTPA]), and transit (geometric center ratio of (51)Cr) were assessed in 29 rats with carbon tetrachloride (CCl(4)) cirrhosis and 20 controls. These variables were then measured in 12 placebo- and in 13 propranolol-treated ascitic cirrhotic rats. Bacterial translocation was present in 48% of the cirrhotic rats and in none of the controls. Cirrhotic rats with intestinal bacterial overgrowth had a significantly higher rate of translocation and slower intestinal transit than those without it. Among the 15 rats with overgrowth and a (99m)Tc-DTPA excretion greater than 10%, 15 had translocation and 2 had bacterial peritonitis. Only 1 of the 14 rats with either intestinal overgrowth or a (99m)Tc-DTPA excretion greater than 10% presented translocation. Compared with the placebo group, propranolol-treated animals had significantly lower portal pressure, faster intestinal transit, and lower rates of bacterial overgrowth and translocation. In ascitic cirrhotic rats, bacterial translocation results from intestinal overgrowth and severe damage to gut permeability. In this setting, intestinal overgrowth is associated with intestinal hypomotility. Propranolol accelerates the intestinal transit, decreasing the rates of bacterial overgrowth and translocation.     

Small intestinal bacterial overgrowth in patients with cirrhosis: prevalence and relation with spontaneous bacterial peritonitis

OBJECTIVES: The significance of small intestinal bacterial overgrowth in patients with cirrhosis is not fully understood and its diagnostic criteria are not uniform. We examined the association of small intestinal bacterial overgrowth with spontaneous bacterial peritonitis and compared various microbiological criteria. METHODS: Jejunal secretions from 70 patients with cirrhosis were cultivated quantitatively and classified according to various definitions. Clinical characteristics of patients were evaluated and the incidence of spontaneous bacterial peritonitis was monitored during a 1-yr follow-up. RESULTS: Small intestinal bacterial overgrowth, defined as > or = 10(5) total colony-forming units/ml jejunal secretions, was present in 61% of patients. Small intestinal bacterial overgrowth was associated with acid-suppressive therapy (p = 0.01) and hypochlorhydria (p < 0.001). Twenty-nine patients with persistent ascites were observed. Six episodes of spontaneous bacterial peritonitis occurred after an average 12.8 wk. Occurence of spontaneous bacterial peritonitis correlated with ascitic fluid protein concentration (p = 0.01) and serum bilirubin (p = 0.04) but not with small intestinal bacterial overgrowth (p = 0.39). Its association with acid-suppressive therapy was of borderline significance (hazard ratio = 7.0, p = 0.08). CONCLUSIONS: Small intestinal bacterial overgrowth in cirrhotic patients is associated with acid-suppressive therapy and hypochlorhydria, but not with spontaneous bacterial peritonitis. The potential role of acid-suppressive therapy in the pathogenesis of spontaneous bacterial peritonitis merits further studies.     

Effect of Lactobacillus johnsonii La1 and antioxidants on intestinal flora and bacterial translocation in rats with experimental cirrhosis

BACKGROUND/AIMS: Probiotics and antioxidants could be alternatives to antibiotics in the prevention of bacterial infections in cirrhosis. The aim of the present study was to determine the effect of Lactobacillus johnsonii La1 and antioxidants on intestinal flora, endotoxemia, and bacterial translocation in cirrhotic rats. METHODS: Twenty-nine Sprague-Dawley rats with cirrhosis induced by CCl(4) and ascites received Lactobacillus johnsonii La1 10(9)cfu/day in vehicle (antioxidants: vitamin C+glutamate) (n=10), vehicle alone (n=11), or water (n=8) by gavage. Another eight non-cirrhotic rats formed the control group. After 10 days of treatment, a laparotomy was performed to determine microbiological study of ileal and cecal feces, bacterial translocation, endotoxemia, and intestinal malondialdehyde (MDA) levels as index of intestinal oxidative damage. RESULTS: Intestinal enterobacteria and enterococci, bacterial translocation (0/11 and 0/10 vs. 5/8, P<0.01), and ileal MDA levels (P<0.01) were lower in cirrhotic rats treated with antioxidants alone or in combination with Lactobacillus johnsonii La1 compared to cirrhotic rats receiving water. Only rats treated with antioxidants and Lactobacillus johnsonii La1 showed a decrease in endotoxemia with respect to cirrhotic rats receiving water (P<0.05). CONCLUSIONS: Antioxidants alone or in combination with Lactobacillus johnsonii La1 can be useful in preventing bacterial translocation in cirrhosis.     

Intestinal bacterial flora, intestinal pathology, and lipopolysaccharide-induced translocation of intestinal bacteria.

The primary aim of this study was to clarify the mechanism and significance of lipopolysaccharide (LPS)-induced translocation of intestinal bacteria. Female Swiss Webster mice were purchased from two different animal suppliers. Twenty-four hours following parenteral LPS, mice from both suppliers had noticeable morbidity and mortality. However, intestinal pathology, gram-negative bacterial overgrowth, and increased bacterial translocation was noted in mice purchased from one supplier but not the other. Mice with increased translocation also had overgrowth of cecal gram-negative bacilli, i.e., 10(10) per gram of cecum following parenteral LPS; in contrast, mice without LPS-induced bacterial translocation had 1,000- to 10,000-fold fewer cecal gram-negative bacilli. Additional groups of mice with increased bacterial translocation were also sacrificed two and 6 hr after parenteral LPS; morbidity and intestinal pathology were evident without a corresponding increase in bacterial translocation. Separate groups of these mice were also injected with platelet activating factor, resulting in intestinal pathology similar to that noted with parenteral LPS, but no increase in bacterial translocation. Thus parenteral LPS was consistently associated with morbidity and mortality but not with intestinal pathology, enteric bacterial overgrowth, or increased bacterial translocation.     

Alterations in rat intestinal transit by morphine promote bacterial translocation

Translocation of enteric microorganisms from the intestinal tract to extraintestinal sites has been proposed as an early step in the development of gram-negative sepsis. This study examined the role of altered bowel transit in influencing intestinal bacteriostasis and bacterial translocation using morphine as a pharmacologic inhibitor of such transit. In the first experiment, either normal saline (N=8) or morphine sulfate (20 mg/kg;N=8) was injected subcutaneously. Two hours later, morphine (7.5 mg/kg) was infused subcutaneously for an additional 22 hr; control animals received saline alone. After completion of this regimen, a volume of 0.2 ml of 2.5 mM FITC dextrans (10,000 daltons) were injected intraduodenally in each group. The bowel was removed 25 min later, divided into 5-cm segments, and the content of dextrans measured. Small bowel propulsion was expressed as the geometric center of the distribution of dextrans throughout the intestine (in percentage length of small bowel). Gut propulsion was significantly reduced after morphine treatment as compared to controls (32.8±8.2% vs 55.8±4.0%;P<0.01). In 16 additional rats, saline or morphine was again administered as described. After 24 hr, samples were obtained from the mesenteric lymph node (MLN) complex, blood, spleen, liver, duodenum, jejunum, ileum, and cecum for standard bacteriology. The bacterial counts increased significantly in each intestinal segment following morphine treatment. Microorganisms translocated to the MLN complex in 5, and to distant sites in four of eight morphine-treated animals, respectively. Translocation to the MLN complex occurred in only one of eight controls (P<0.05); no translocation to distant sites occurred in control animals. We conclude that the morphine-induced prolongation in bowel transit promotes bacterial translocation secondary to an overgrowth of enteric bacteria in the intestinal lumen.Supported by NIH grant GM 38529 and the DFG grant Ru 387/1-2.     

Effects of pentoxifylline on intestinal bacterial overgrowth, bacterial translocation and spontaneous bacterial peritonitis in cirrhotic rats with ascites

BackgroundProphylaxis of spontaneous bacterial peritonitis with norfloxacin has been associated to development of antibiotic resistance. We investigated whether pentoxifylline compared to norfloxacin reduces bacterial translocation and spontaneous bacterial peritonitis in rats with CCl₄-induced cirrhosis and ascites.MethodAfter development of cirrhosis and ascites, animals were randomly allocated to receive pentoxifylline (16 mg/kg/d every 8 h, oral route, n = 13) or placebo (n = 12) for 15 days. An additional group of 8 cirrhotic rats was given norfloxacin (5 mg/kg/d for 15 days). Six healthy rats served as controls. Cecal flora and the prevalence of bacterial translocation and spontaneous bacterial peritonitis were analysed. Serum and ascitic fluid levels of TNF-alpha and cecal levels of malondialdehyde were also measured.ResultsPentoxifylline in comparison to placebo reduced intestinal bacterial overgrowth (21% vs. 67%, p = 0.04), bacterial translocation to cecal lymph nodes (23% vs. 75%, p = 0.03) and prevented spontaneous bacterial peritonitis (0% vs. 33%, p = 0.04) by Enterobacteriaceae. Norfloxacin administration induced similar results. Pentoxifylline (0.18 ± 0.10 nmol/mg), but not norfloxacin (0.25 ± 0.13; p = 0.02), significantly reduced cecal mucosal levels of malondialdehyde compared to placebo (0.33 ± 0.16; p = 0.03).ConclusionIn cirrhotic rats with ascites: (a) pentoxifylline as well as norfloxacin reduced intestinal bacterial overgrowth and bacterial translocation and prevented spontaneous bacterial peritonitis; (b) pentoxifylline, but not norfloxacin, reduced oxidative stress in cecal mucosal.     

Intestinal mucosal oxidative damage and bacterial translocation in cirrhotic rats

BACKGROUND: Bacterial translocation plays an important role in the pathogenesis of spontaneous bacterial peritonitis mainly due to intestinal bacterial overgrowth. Alterations in the functional integrity of the intestinal barrier caused by an increased production of free radical metabolites as a consequence of portal hypertension could also facilitate bacterial translocation in cirrhotic rats. OBJECTIVE: The aim of the study was to determine intestinal mucosal lipid peroxidation and neutrophil infiltration and their relationship with portal hypertension and bacterial translocation in cirrhotic rats. DESIGN: Eighteen male Sprague-Dawley rats with cirrhosis induced by carbon tetrachloride, administered by gavage, and eight control rats were included in the study. METHODS: Samples of jejunum, ileum and caecum were obtained by laparotomy for the determination of malondialdehyde and myeloperoxidase as indexes of lipid peroxidation and neutrophil infiltration, respectively. Samples of ascitic and pleural fluids, mesenteric lymph nodes and ileal stools were obtained for the culture of microoganisms. RESULTS: The concentration of malondialdehyde was significantly higher in ileal and caecal, but not in jejunal mucosa, in cirrhotic rats, mainly in those with ascites (P< 0.01), as compared to control rats (P< 0.01), and in cirrhotic rats with bacterial translocation compared to those without bacterial translocation (P< 0.01). No differences between groups were observed in the concentrations of myeloperoxidase in jejunum, ileum or caecum. A direct correlation between ileal malondialdehyde and portal pressure was observed (P< 0.01). CONCLUSIONS: Cirrhotic rats, particularly those with ascites and bacterial translocation, show increased malondialdehyde levels in ileal and caecal mucosa. These results suggest that mucosal oxidative damage in ileum and caecum could favour bacterial translocation in cirrhotic rats.     

Pathological bacterial translocation in cirrhosis: pathophysiology,diagnosis and clinical implications

Bacterial translocation (BT) is defined by the passage of viable indigenous bacteria from the intestinal lumen to mesenteric lymph nodes (MLNs) and other territories, and its diagnostic criteria rely on the isolation of viable bacteria in MLNs. Small intestinal overgrowth, increased intestinal permeability and immunological alterations are the main factors involved in its pathogenesis. BT is obviously difficult to identify in patients with cirrhosis, and alternative methods have been proposed instead. Bacterial DNA detection and species identification in serum or ascitic fluid has been proposed as a reliable marker of BT. Bacterial products, such as endotoxin, or bacterial DNA can translocate to extra‐intestinal sites and promote an immunological response similar to that produced by viable bacteria. Therefore, pathological BT plays an important role in the pathogenesis of the complications of cirrhosis, not only in infections, but by exerting a profound inflammatory state and exacerbating the haemodynamic derangement. This may promote in turn the development of hepatorenal syndrome, hepatic encephalopathy and other portal hypertension‐related complications. Therapeutic approaches for the prevention of BT in experimental and human cirrhosis are summarized. Finally, new investigations are needed to better understand the pathogenesis and consequences of translocation by viable bacteria (able to grow in culture), or non‐viable BT (detection of bacterial fragments with negative culture) and open new therapeutic avenues in patients with cirrhosis.     

Oral bile acids reduce bacterial overgrowth,bacterial translocation,and endotoxemia in cirrhotic rats

Experiments were performed to test whether conjugated bile acid administration would decrease bacterial overgrowth, bacterial translocation, and endotoxemia in ascitic cirrhotic rats. Cholylsarcosine, a deconjugation-dehydroxylation resistant and cholylglycine, a deconjugation-dehydroxylation susceptible bile acid were used. Rats with CCl(4)-induced cirrhosis and ascites were fed cholylsarcosine, cholylglycine (both at 70 mg/kg/d), or placebo for 2 weeks. Healthy rats, as controls, were treated similarly. In cirrhotic rats receiving placebo, bile secretion from an acute biliary fistula was lower than in healthy rats (27.2 +/- 6.5 vs. 53.0 +/- 3.1 microL/kg/min; mean +/- SE, P<.05). The administration of conjugated bile acids to cirrhotic rats normalized bile secretion (cholylsarcosine, 51.8 +/- 6.29; cholylglycine, 52.72 +/- 8.9 microL/kg/min). Total ileal bacterial content was 6-fold higher in ascitic cirrhotic rats than in healthy rats. Conjugated bile acid administration reduced bacterial content to normal levels. Bacterial translocation was less in cirrhotic animals receiving conjugated bile acids (cholylsarcosine, 33%; cholylglycine, 26%) than in animals receiving placebo (66%). Endotoxemia was decreased in cirrhotic rats by conjugated bile acid feeding (cholylsarcosine, 0.098 +/- 0.002; cholylglycine 0.101 +/- 0.007 EU/mL) compared with placebo (0.282 +/- 0.124, P <.001). Survival was greater in animals receiving conjugated bile acids (cholylsarcosine, 10/15; cholylglycine, 11/15; placebo, 5/15). In conclusion, the administration of conjugated bile acids to ascitic cirrhotic rats increased bile acid secretion, eliminated intestinal bacterial overgrowth, decreased bacterial translocation, decreased endotoxemia, and increased survival. Oral conjugated bile acids may be useful in preventing bacterial translocation, endotoxemia, and spontaneous bacterial perotonitis in cirrhotic patients.     

Intestinal bacterial translocation in rats with cirrhosis is related to compromised Paneth cell antimicrobial host defense

Liver cirrhosis is associated with bacterial translocation (BT) and endotoxemia. Most translocating bacteria belong to the common intestinal microbiota, suggesting a breakdown of intestinal barrier function. We hypothesized that diminished mucosal antimicrobial host defense could predispose to BT. Two rodent models of portal hypertension with increased BT were used, CCl(4)-induced ascitic cirrhosis and 2-day portal vein-ligated (PVL) animals. BT was assessed by standard microbiological techniques on mesenteric lymph nodes. Total RNA was isolated systematically throughout the intestinal tract, and expression of Paneth cell α-cryptdins and β-defensins was determined by real-time quantitative polymerase chain reaction (qPCR). To determine functional consequences, mucosal antimicrobial activity was assessed with a fluorescence-activated cell sorting assay. BT was detectable in 40% of rats with cirrhosis. Compared with the group without BT, these animals exhibited diminished intestinal Paneth cell α-cryptdin 5 and 7 expression. In contrast, PVL was associated with BT in all animals but did not affect antimicrobial peptides. The decrease in Paneth cell antimicrobials was most pronounced in the ileum and the coecum. Other antimicrobials showed no changes or even an induction in the case of BT at different sites. Antimicrobial activity toward different commensal strains was reduced, especially in the distal ileum and the cecum in experimental cirrhosis with BT (excluding PVL). Conclusion: Compromised Paneth cell antimicrobial host defense seems to predispose to BT in experimental cirrhosis. Understanding this liver-gut axis including the underlying mechanisms could help us to find new treatment avenues.     

Leaky Gut and Gut-Liver Axis in Liver Cirrhosis: Clinical Studies Update

Portal blood flows into the liver containing the gut microbiome and its products such as endotoxin and bacterial DNA. The cirrhotic liver acts and detoxifies as the initial site of microbial products. In so-called “leaky gut,” the increased intestinal permeability for bacteria and their products constitutes an important pathogenetic factor for major complications in patients with liver cirrhosis. Prolonged gastric and small intestinal transit may induce intestinal bacterial overgrowth, a condition in which colonic bacteria translocate into the small gut. Cirrhotic patients further show gut dysbiosis characterized by an overgrowth of potentially pathogenic bacteria and a decrease in autochthonous nonpathogenic bacteria. Pathological bacterial translocation (BT) is a contributing factor in the development of various severe complications. Bile acids (BAs) undergo extensive enterohepatic circulation and play important roles in the gut-liver axis. BT-induced inflammation prevents synthesis of BAs in the liver through inhibition of BA-synthesizing enzyme CYP7A1. A lower abundance of 7α-dehydroxylating gut bacteria leads to decreased conversion of primary to secondary BAs. Decreases in total and secondary BAs may play an important role in the gut dysbiosis characterized by a proinflammatory and toxic gut microbiome inducing BT and endotoxemia, as addressed in my previous reviews. Selective intestinal decontamination by the use of various antimicrobial drugs for management of complications has a long history. Lactobacillus GG decreasing endotoxemia is reported to improve the microbiome with beneficial changes in amino acid, vitamin and secondary BA metabolism. Current approaches for hepatic encephalopathy are the use of nonabsorbable antibiotics and disaccharides. Probiotics may become an additional therapeutic option for advanced liver cirrhosis. (Gut Liver 2021;15:-676)     

肝硬化患者腹水中细菌DNA与相关因素的关系

目的 探讨肝硬化患者腹水中细菌DNA与血浆内毒素、肠通透性、肠道菌群等因素的关系. 方法 选取失代偿期肝硬化伴腹水患者55例,于入院当日或次日抽取腹水行腹水中细菌DNA的提取及PCR扩增,同时行腹水常规、需氧菌及厌氧菌培养检查,于入院次日测定血浆内毒素、肠通透性并进行肠道菌群分析,同时测定血常规、肝肾功能、凝血功能等生物化学指标.30例健康成年人作为正常对照,行除腹水之外的上述检查. 结果 55例肝硬化患者腹水细菌培养均为阴性,其中19例(34.55%)患者腹水中检测到细菌DNA.与细菌DNA阴性组比较,细菌DNA阳性组患者的凝血酶原活动度明显降低(t=-3.184,P=0.002),而肝功能Child-Pugh评分(t=3.224,P=0.002)和腹水白细胞计数(t'=4.088,P=0.001)明显升高.与正常对照组比较,肝硬化患者血浆内毒素水平(t=13.705,P=0.000)、尿中乳果糖/甘露醇(L/M,t'=28.568,P=0.000)和肠道肠杆菌数量(t=2.912,P=0.005)明显升高,而肠道双歧杆菌数量明显减少(t=-3.669,P=0.000).与腹水中细菌DNA相关的指标为肠道肠杆菌数量(P=0.007)和凝血酶原活动度(P=0.011).结论 肝硬化患者发生腹水细菌移位的关键因素是肠腔细菌过度生长,并与肝病的严重程度相关.     

Insulin-like growth factor I improves intestinal barrier function in cirrhotic rats

BACKGROUND AND AIMS: In liver cirrhosis, disruption of the intestinal barrier facilitates bacterial translocation and spontaneous bacterial peritonitis. Insulin-like growth factor I (IGF-I) is an anabolic hormone synthesised by hepatocytes that displays hepatoprotective activities and trophic effects on the intestine. The aim of this study was to investigate the effect of IGF-I on intestinal barrier function in cirrhotic rats. METHODS: In rats with carbon tetrachloride induced cirrhosis, we investigated the effect of IGF-I therapy on: (a) portal pressure; (b) intestinal histology and permeability to endotoxin and bacteria; (c) intestinal expression of cyclooxygenase 2 (COX-2) and tumour necrosis factor alpha (TNF-alpha), two factors that influence in a positive and negative manner, respectively, the integrity of the intestinal barrier; (d) intestinal permeability to 3H-mannitol in rats with bile duct ligation (BDL); and (e) transepithelial electrical resistance (TER) of polarised monolayers of rat small intestine epithelial cells. RESULTS: IGF-I therapy reduced liver collagen expression and portal pressure in cirrhotic rats, induced improvement in intestinal histology, and caused a reduction in bacterial translocation and endotoxaemia. These changes were associated with diminished TNF-alpha expression and elevated COX-2 levels in the intestine. IGF-I reduced intestinal permeability in BDL rats and enhanced barrier function of the monolayers of epithelial intestinal cells where lipopolysaccharide (LPS) caused a decrease in TER that was reversed by IGF-I. This effect of IGF-I was associated with upregulation of COX-2 in LPS treated enterocytes. CONCLUSIONS: IGF-I enhances intestinal barrier function and reduces endotoxaemia and bacterial translocation in cirrhotic rats. IGF-I therapy might be useful in the prevention of spontaneous bacterial peritonitis in liver cirrhosis.     

Intestinal barrier dysfunction in developing liver cirrhosis: An in vivo analysis of bacterial translocation

Aim: Transmucosal passage of bacteria across the intestine, the essential step for bacterial translocation, has been identified as a key event in the pathogenesis of life-threatening infections in cirrhosis. Existing animal models of liver cirrhosis only provide indirect information about the pathogenesis of such infections. The aim of this study has been to assess transmucosal passage and bacterial translocation directly in vivo using a rat model of developing liver cirrhosis. Methods: Male Sprague Dawley rats were randomly assigned to two groups: controls and animals with developing liver cirrhosis induced by s.c. injection of carbon tetrachloride. In anesthetized animals a suspension of green fluorescent protein (GFP)-tagged E. coli was administered into the terminal ileum. Time intervals necessary for translocation of E. coli into the mucosa and muscularis were assessed by intravital microscopy and translocation of E. coli in mesentery, liver and spleen was determined microbiologically. Results: Bacterial kinetics at the level of the mucosa and muscularis showed significant enhancement in cirrhotic rats compared to the controls (P < 0.001). GFP-expressing E. coli were detected in the mesentery, liver and spleen of animals with cirrhosis taken one hour after E. coli administration. However, cultures of control animals remained sterile. Conclusion: Intravital microscopy of fluorescent bacteria represents a novel approach to studying bacterial translocation in vivo. Here we report that this technique can be used to visualize bacterial transit in in vivo and gives further support to the transmucosal passage of bacteria across the intestine correlating with bacterial translocation in CCl(4)-induced liver cirrhosis.     

Small intestinal bacterial overgrowth in human cirrhosis is associated with systemic endotoxemia

OBJECTIVES: Systemic endotoxemia has been implicated in various pathophysiological sequelae of chronic liver disease. One of its potential causes is increased intestinal absorption of endotoxin. We therefore examined the association of small intestinal bacterial overgrowth with systemic endotoxemia in patients with cirrhosis. METHODS: Fifty-three consecutive patients with cirrhosis (Child-Pugh group A, 23; group B, 18; group C, 12) were included. Jejunal secretions were cultivated quantitatively and systemic endotoxemia determined by the chromogenic Limulus amoebocyte assay. Patients were followed up for 1 yr. RESULTS: Small intestinal bacterial overgrowth, defined as > or = 10(5) total colony forming units per milliliter of jejunal secretions, was present in 59% of patients and strongly associated with acid suppressive therapy. The mean plasma endotoxin level was 0.86 +/- 0.48 endotoxin units/ml (range = 0.03-1.44) and was significantly associated with small intestinal bacterial overgrowth (0.99 vs 0.60 endotoxin units/ml, p = 0.03). During the 1-yr follow-up, seven patients were lost to follow up or underwent liver transplantation and 12 patients died. Multivariate Cox regression showed Child-Pugh group to be the only predictor for survival. CONCLUSIONS: Small intestinal bacterial overgrowth in cirrhotic patients is common and associated with systemic endotoxemia. The clinical relevance of this association remains to be defined.     

Leaky gut and the liver: a role for bacterial translocation in nonalcoholic steatohepatitis

Gut flora and bacterial translocation (BT) play important roles in the pathogenesis of chronic liver disease, including cirrhosis and its complications. Intestinal bacterial overgrowth and increased bacterial translocation of gut flora from the intestinal lumen predispose patients to bacterial infections, major complications and also play a role in the pathogenesis of chronic liver disorders. Levels of bacterial lipopolysaccharide, a component of gram-negative bacteria, are increased in the portal and/or systemic circulation in several types of chronic liver disease. Impaired gut epithelial integrity due to alterations in tight junction proteins may be the pathological mechanism underlying bacterial translocation. Preclinical and clinical studies over the last decade have suggested a role for BT in the pathogenesis of nonalcoholic steatohepatitis (NASH). Bacterial overgrowth, immune dysfunction, alteration of the luminal factors, and altered intestinal permeability are all involved in the pathogenesis of NASH and its complications. A better understanding of the cell-specific recognition and intracellular signaling events involved in sensing gut-derived microbes will help in the development of means to achieve an optimal balance in the gut-liver axis and ameliorate liver diseases. These may suggest new targets for potential therapeutic interventions for the treatment of NASH. Here, we review some of the mechanisms connecting BT and NASH and potential therapeutic developments.