Intestinal mucosal oxidative damage and bacterial translocation in cirrhotic rats

Lipid peroxidation and liver damage in double and simple common bile duct ligation models in male Sprague-Dawley rats

AIMS

Bacterial translocation, defined as the presence of living bacteria or bacterial fragments in both mesenteric lymph nodes or systemic circulation, can cause a severe inflammatory reaction in patients with cirrhosis. This study aimed to compare lipid peroxidation associated with liver damage in different experimental models of bile duct ligation: proximal double ligation and transection versus proximal simple ligation versus sham.

MATERIALS AND METHODS

Sixty-two male rats underwent one of three bile duct surgical interventions: proximal double ligation and transection (n = 22); proximal simple ligation (n = 19); or sham operation (n = 21). We performed microbiological culture of mesenteric lymph nodes; portal and cava blood, spleen and liver cultures; and histological analysis of liver parenchyma. Samples of blood and liver were obtained at laparotomy for malondialdehyde quantification.

KEY FINDINGS

Serum malondialdehyde levels were significantly higher in simple ligature animals (3.7 nmol/mg, standard deviation [SD] 2.1) compared to controls (1.6 nmol/mg SD 0.5; p = 0.001) or double ligature (0.3 nmol/mg SD 0.3; p = 0.001). Liver malondialdehyde levels were significantly higher in animals subjected to double ligation vs controls (9.0 nmol/mg SD 2.8 vs. 1.7 nmol/mg SD 1.0; p = 0.0007) and simple ligature (2.9 nmol/mg SD 2.0; p = 0.0001). Overall incidence of bacterial translocation was similar in simple and double ligatures (22.2 % and 21 % respectively), and significantly higher than in controls.

SIGNIFICANCE

the type of bile duct ligation influences the type and localization of lipid peroxidation, but does not influence the development of bacterial translocation.

Anti-inflammatory effect of Lactiplantibacillus plantarum T1 cell-free supernatants through suppression of oxidative stress and NF-κB- and MAPK-signaling pathways

Lactiplantibacillus plantarum T1 is an isolated probiotic lactic acid bacterium (LAB) from pickled vegetables in Chongqing, China. In this study, we evaluated the anti-inflammatory activity and the underlying mechanisms of L. plantarum T1 cell-free supernatant (CFS) on lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophages in vitro. Reverse transcription quantitative PCR (RT-qPCR), immunofluorescence, Griess methods, and western blotting were utilized to assess the anti-inflammatory cytokines and antioxidative effect of L. plantarum T1 CFS. Our results showed that L. plantarum T1 CFS pretreatment significantly reduced pro-inflammatory cytokine levels, including nitric oxide, inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor, interleukin (IL)-1β, and IL-6, as well as reactive oxygen species. Interestingly, L. plantarum T1 CFS unregulated the antioxidant indicators, including superoxide dismutase, catalase, and glutathione in RAW264.7 cells. Furthermore, L. plantarum T1 CFS activated the nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) pathway. This study showed the excellent antioxidant and anti-inflammatory properties of L. plantarum T1 through multiple pathways, highlighting its potential for further research and application as a probiotic strain.IMPORTANCEL. plantarum T1 stood out in a series of acid and bile salt tolerance and bacterial inhibition tests as a probiotic isolated from paocai, which provides many health benefits to the host by inhibiting the growth of harmful pathogenic microorganisms and suppressing excessive levels of oxidative stress and inflammation. Not all LAB have good probiotic functions and are used in various applications. The anti-inflammatory antioxidant potential and mechanisms of L. plantarum T1 CFS have not been described and reported. By using RT-qPCR, Griess method, and western blotting, we showed that L. plantarum T1 CFS had anti-inflammatory and antioxidant effects. Griess assay, TBA assay, WST-8 assay, immunofluorescence assay, RT-qPCR, and western blotting data revealed that its anti-inflammatory and antioxidant mechanisms were associated with oxidative stress and NF-κB and MAPK signaling pathways. The anti-inflammatory and antioxidant effects of L. plantarum T1 CFS in paocai generates opportunities for probiotic product development.

Caffeine citrate effects on gastrointestinal permeability, bacterial translocation and biochemical parameters in newborn rats after long-term oral administration

BACKGROUND: Caffeine is a potent central and respiratory acting agent used in neonatology to treat apnea in premature newborns. OBJECTIVE: This study investigates the effects of caffeine orally administered to newborn rats on gastrointestinal permeability, bacterial translocation and different biochemical parameters. METHODS: Newborn rats were divided into different groups (N = 06). The treated newborn rats were orally administered with standard caffeine doses (12 mg/kg per day), and the control groups received a placebo. The animals were weighed daily until sacrifice. Blood samples, mesenteric lymph nodes (MLN) and organs were aseptically collected. Furthermore, different biochemical (D-Lactate) and oxidative stress biomarkers (MDA, CAT, SOD and GSH) levels were examined. Microbiological analyses were performed to assess microbiota alterations and bacterial translocation. RESULTS: Preliminary results showed that caffeine administration decreased the level of bacterial translocation over time. The treatment reduced plasma D-lactate levels (p <  0.05). Additionally, caffeine induced a disturbance in the concentrations of biochemical parameters and oxidative stress biomarkers. Indeed, liver enzymes (AST and ALT) were significantly (p <  0.05) risen after caffeine treatment. Glutathione (GSH) levels were significantly higher in caffeine treated groups (75.12±0.32; 51.98±1.12 U/mg; p <  0.05) comparing to control ones (40.82±0.25; 42.91±0.27 U/mg; p <  0.05) in the ileum and the colon, respectively. CONCLUSIONS: Thus, besides improving gastrointestinal permeability, our data show that caffeine has beneficial effects on the intestinal antioxidant system.

Enterococcus spp.: Is It a Bad Choice for a Good Use-A Conundrum to Solve?

Since antiquity, the ubiquitous lactic acid bacteria (LAB) Enterococci, which are just as predominant in both human and animal intestinal commensal flora, have been used (and still are) as probiotics in food and feed production. Their qualities encounter several hurdles, particularly in terms of the array of virulence determinants, reflecting a notorious reputation that nearly prevents their use as probiotics. Additionally, representatives of the Enterococcus spp. genus showed intrinsic resistance to several antimicrobial agents, and flexibility to acquire resistance determinants encoded on a broad array of conjugative plasmids, transposons, and bacteriophages. The presence of such pathogenic aspects among some species represents a critical barrier compromising their use as probiotics in food. Thus, the genus neither has Generally Recognized as Safe (GRAS) status nor has it been included in the Qualified Presumption of Safety (QPS) list implying drastic legislation towards these microorganisms. To date, the knowledge of the virulence factors and the genetic structure of foodborne enterococcal strains is rather limited. Although enterococcal infections originating from food have never been reported, the consumption of food carrying virulence enterococci seems to be a risky path of transfer, and hence, it renders them poor choices as probiotics. Auspiciously, enterococcal virulence factors seem to be strain specific suggesting that clinical isolates carry much more determinants that food isolates. The latter remain widely susceptible to clinically relevant antibiotics and subsequently, have a lower potential for pathogenicity. In terms of the ideal enterococcal candidate, selected strains deemed for use in foods should not possess any virulence genes and should be susceptible to clinically relevant antibiotics. Overall, implementation of an appropriate risk/benefit analysis, in addition to the case-by-case assessment, the establishment of a strain's innocuity, and consideration for relevant guidelines, legislation, and regulatory aspects surrounding functional food development seem to be the crucial elements for industries, health-staff and consumers to accept enterococci, like other LAB, as important candidates for useful and beneficial applications in food industry and food biotechnology. The present review aims at shedding light on the world of hurdles and limitations that hampers the Enterococcus spp. genus and its representatives from being used or proposed for use as probiotics. The future of enterococci use as probiotics and legislation in this field are also discussed.

Plasma metabolites associated with physiological and biochemical indexes indicate the effect of caging stress on mallard ducks (Anas platyrhynchos)

Objective

Cage rearing has critical implications for the laying duck industry because it is convenient for feeding and management. However, caging stress is a type of chronic stress that induces maladaptation. Environmental stress responses have been extensively studied, but no detailed information is available about the comprehensive changes in plasma metabolites at different stages of caging stress in ducks. We designed this experiment to analyze the effects of caging stress on performance parameters and oxidative stress indexes in ducks.

Methods

Liquid chromatography tandem mass spectrometry (LC/MS-MS) was used to determine the changes in metabolites in duck plasma at 5 (CR5), 10 (CR10), and 15 (CR15) days after cage rearing and traditional breeding (TB). The associated pathways of differentially altered metabolites were analyzed using Kyoto encyclopedia of genes and genomes (KEGG) database.

Results

The results of this study indicate that caging stress decreased performance parameters, and the plasma total superoxide dismutase levels were increased in the CR10 group compared with the other groups. In addition, 1,431 metabolites were detected. Compared with the TB group, 134, 381, and 190 differentially produced metabolites were identified in the CR5, CR10, and CR15 groups, respectively. The results of principal component analysis (PCA) show that the selected components sufficiently distinguish the TB group and CR10 group. KEGG analysis results revealed that the differentially altered metabolites in duck plasma from the CR5 and TB groups were mainly associated with ovarian steroidogenesis, biosynthesis of unsaturated fatty acids, and phenylalanine metabolism.

Conclusion

In this study, the production performance, blood indexes, number of metabolites and PCA were compared to determine effect of the caging stress stage on ducks. We inferred from the experimental results that caging-stressed ducks were in the sensitive phase in the first 5 days after caging, caging for approximately 10 days was an important transition phase, and then the duck continually adapted.

Intestinal Permeability Is a Mechanical Rheostat in the Pathogenesis of Liver Cirrhosis

Recent studies have suggested that an alteration in the gut microbiota and their products, particularly endotoxins derived from Gram-negative bacteria, may play a major role in the pathogenesis of liver diseases. Gut dysbiosis caused by a high-fat diet and alcohol consumption induces increased intestinal permeability, which means higher translocation of bacteria and their products and components, including endotoxins, the so-called "leaky gut". Clinical studies have found that plasma endotoxin levels are elevated in patients with chronic liver diseases, including alcoholic liver disease and nonalcoholic liver disease. A decrease in commensal nonpathogenic bacteria including Ruminococaceae and Lactobacillus and an overgrowth of pathogenic bacteria such as Bacteroidaceae and Enterobacteriaceae are observed in cirrhotic patients. The decreased diversity of the gut microbiota in cirrhotic patients before liver transplantation is also related to a higher incidence of post-transplant infections and cognitive impairment. The exposure to endotoxins activates macrophages via Toll-like receptor 4 (TLR4), leading to a greater production of proinflammatory cytokines and chemokines including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-8, which play key roles in the progression of liver diseases. TLR4 is a major receptor activated by the binding of endotoxins in macrophages, and its downstream signal induces proinflammatory cytokines. The expression of TLR4 is also observed in nonimmune cells in the liver, such as hepatic stellate cells, which play a crucial role in the progression of liver fibrosis that develops into hepatocarcinogenesis, suggesting the importance of the interaction between endotoxemia and TLR4 signaling as a target for preventing liver disease progression. In this review, we summarize the findings for the role of gut-derived endotoxemia underlying the progression of liver pathogenesis.

Research Advances in Protective Effects of Ursolic Acid and Oleanolic Acid Against Gastrointestinal Diseases

The intestinal tract plays an essential role in protecting tissues from the invasion of external harmful substances due to impaired barrier function. Furthermore, it participates in immunomodulation by intestinal microorganisms, which is important in health. When the intestinal tract is destroyed, it can lose its protective function, resulting in multiple systemic complications. In severe cases, it may lead to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Thus far, there are no curative therapies for intestinal mucosal barrier injury, other than a few drugs that can relieve symptoms. Thus, the development of novel curative agents for gastrointestinal diseases remains a challenge. Ursolic acid (UA) and its isomer, Oleanolic acid (OA), are pentacyclic triterpene acid compounds. Both their aglycone and glycoside forms have anti-oxidative, anti-inflammatory, anti-ulcer, antibacterial, antiviral, antihypertensive, anti-obesity, anticancer, antidiabetic, cardio protective, hepatoprotective, and anti-neurodegenerative properties in living organisms. In recent years, several studies have shown that UA and OA can reduce the risk of intestinal pathological injury, alleviate intestinal dysfunction, and restore intestinal barrier function. The present study evaluated the beneficial effects of UA and OA on intestinal damage and diseases, including inflammatory bowel disease (IBD) and colorectal cancer (CRC).

Oral administration of thiol-reducing agents mitigates gut barrier disintegrity and bacterial lipopolysaccharide translocation in a rat model of biliary obstruction

It has been well documented that cirrhosis is associated with the intestinal injury. Intestinal injury in cirrhosis could lead to bacterial lipopolysaccharide (LPS) translocation to the systemic circulation. It has been found that high plasma LPS is connected with higher morbidity and mortality in cirrhotic patients. Therefore, finding therapeutic approaches to mitigate this complication has great clinical value. Several investigations mentioned the pivotal role of oxidative stress in cirrhosis-associated intestinal injury. It has been well-known that the redox balance of enterocytes is disturbed in cirrhotic patients. In the current study, the effects of thiol-reducing agents N-acetylcysteine (NAC) (0.5 and 1% w: v) and dithiothreitol (DTT) (0.5 and 1% w: v) on biomarkers of oxidative stress, tissue histopathological alterations, and LPS translocation is investigated in a rat model of cirrhosis. Bile duct ligation (BDL) surgery was used to induce cirrhosis in male Sprague-Dawley rats. Animals (n ​= ​48; 8 animals/group) were supplemented with NAC and DTT for 28 consecutive days. Significant changes in ileum and colon markers of oxidative stress were evident in BDL rats as judged by increased reactive oxygen species (ROS), lipid peroxidation, oxidized glutathione (GSSG), and protein carbonylation along with decreased antioxidant capacity and glutathione (GSH) content. Blunted villus, decreased villus number, and inflammation was also detected in the intestine of BDL animals. Moreover, serum LPS level was also significantly higher in BDL rats. NAC and DTT administration (0.5 and 1% w: v, gavage) significantly decreased biomarkers of oxidative stress, mitigated intestinal histopathological alterations, and restored tissue antioxidant capacity. Moreover, NAC and/or DTT significantly suppressed LPS translocation to the systemic circulation. The protective effects of thiol reducing agents in the intestine of cirrhotic rats could be attributed to the effect of these chemicals on the cellular redox environment and biomarkers of oxidative stress.

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Gut permeability is a clinical complication in cholestasis/cirrhosis

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Intestinal injury leads to lipopolysaccharide (LPS) translocation to the bloodstream

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LPS translocation to the systemic circulation could cause systemic inflammation

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Oxidative stress is involved in the mechanisms of cirrhosis-induced gut permeability

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Oral administration of thiol-reducing agents mitigated intestinal tissue oxidative stress

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Serum LPS levels were lower in thiol reducing agents-treated animals

Gut microbiota in non-alcoholic fatty liver disease and alcohol-related liver disease: Current concepts and perspectives

The term, gut-liver axis, is used to highlight the close anatomical and functional relationship between the intestine and the liver. It has been increasingly recognized that the gut-liver axis plays an essential role in the development and progression of liver disease. In particular, in non-alcoholic fatty liver disease and alcohol-related liver disease, the two most common causes of chronic liver disease, a dysbiotic gut microbiota can influence intestinal permeability, allowing some pathogens or bacteria-derived factors from the gut reaching the liver through the enterohepatic circulation contributing to liver injury, steatohepatitis, and fibrosis progression. Pathways involved are multiple, including changes in bile acid metabolism, intestinal ethanol production, generation of short-chain fatty acids, and other by-products. Bile acids act through dedicated bile acid receptors, farnesoid X receptor and TGR5, in both the ileum and the liver, influencing lipid metabolism, inflammation, and fibrogenesis. Currently, both non-alcoholic fatty liver disease and alcohol-related liver disease lack effective therapies, and therapeutic targeting of gut microbiota and bile acids enterohepatic circulation holds promise. In this review, we summarize current knowledge about the role of gut microbiota in the pathogenesis of non-alcoholic fatty liver disease and alcohol-related liver disease, as well as the relevance of microbiota or bile acid-based approaches in the management of those liver diseases.

Risks associated with enterococci as probiotics

Probiotics are naturally occurring microorganisms that confer health benefits by altering host commensal microbiota, modulating immunity, enhancing intestinal barrier function, or altering pain perception. Enterococci are human and animal intestinal commensals that are used as probiotics and in food production. These microorganisms, however, express many virulence traits including cytolysin, proteases, aggregation substance, capsular polysaccharide, enterococcal surface protein, biofilm formation, extracellular superoxide, intestinal translocation, and resistance to innate immunity that can lead to serious hospital-acquired infections. In addition, enterococci are facile in acquiring antibiotic resistance genes to many clinically important antibiotics encoded on a wide variety of conjugative plasmids, transposons, and bacteriophages. The pathogenicity and disease burden caused by enterococci render them poor choices as probiotics. No large, randomized, placebo-controlled clinical trials have demonstrated the safety and efficacy of any enterococcal probiotic. As a result, no enterococcal probiotic has been approved by the United States Food and Drug Administration for the treatment, cure, or amelioration of human disease. In 2007, the European Food Safety Authority concluded that enterococci do not meet the standard for "Qualified Presumption of Safety". Enterococcal strains used or proposed for use as probiotics should be carefully screened for efficacy and safety.

Postoperative Portal Hypertension Enhances Alloimmune Responses after Living-Donor Liver Transplantation in Patients and in a Mouse Model

Controlling portal vein pressure in living-donor liver transplantation has received increased attention owing to its potential importance for graft survival. Portal hypertension may lead to the activation of liver-resident APCs, including liver sinusoidal endothelial cells (LSECs), which have immunological tolerogenic capacity. We investigated the effects of portal hypertension on graft survival and the antidonor immune response using clinical data and a mouse model. We categorized patients (n = 136) according to their portal vein pressure values at the end of surgery. Using propensity score-matching analyses, we found that portal hypertension was significantly associated with a higher antidonor immune response and incidence of acute rejection. To investigate the mechanism, we performed an allogeneic coculture assay using a 70% hepatectomized (HTx) mouse model with or without a portosystemic shunt. Liver cells from HTx mice without a shunt exhibited a significantly greater anti-BALB/c B6 T cell response than those from sham-operated mice or HTx mice with a shunt. LSECs from sham-operated mice, but not from HTx mice, suppressed the B6 T cell alloresponse in a dose-dependent manner. Furthermore, LSECs from HTx mice without a shunt showed significantly downregulated MHC class I/II and programmed death-ligand 1 expression, and those from mice with a shunt showed recovered expression of these molecules. Postoperative portal hypertension enhances alloimmune responses in recipients after living-donor liver transplantation, likely due, in part, to the impaired immune-suppression capacity of LSECs.

Isolation, culture, and identification of duck intestinal epithelial cells and oxidative stress model constructed

Intestinal epithelial cells (IECs) not only have an absorption function but also act as a physical barrier between the body and the intestinal bacterial flora. Damage to IECs leads to the breakdown of this barrier and has negative effects on animal health. Intestinal epithelial damage is frequently associated with long-term acute stress, such as increased temperature and new stress management models. The intestinal epithelial damage caused by environmental stress has been linked to oxidative stress. Until now, the effects of intestinal epithelial antioxidant activity from feed additives and treatments could be tested in ducks only in vivo because of the lack of in vitro cell culture systems. In this study, we describe our protocol for the easy isolation and culture of IECs from the small intestine of duck embryos. Immunofluorescence was used for the cytological identification of IECs. In addition, IEC marker genes (IAP and CDH1) could also be detected in cultured cells. And cell status assessments were performed, and cell proliferation viability was analyzed by CCK-8 assay. Furthermore, we constructed an oxidative stress model to be used to research the oxidative stress response mechanism, and drugs acting on the cell signal transduction pathway. In conclusion, we have developed an effective and rapid protocol for obtaining duck primary IECs and constructed an oxidative stress model. These IECs exhibit features consistent with epithelial cells and could be used to explore the physiological mechanisms of oxidative stress ex vivo.

Protective Effect of Ursolic Acid on the Intestinal Mucosal Barrier in a Rat Model of Liver Fibrosis

Oxidative stress mediated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) plays an important role in intestinal mucosal barrier damage in various disease states. Recent evidence suggests that intestinal mucosal barrier damage and intestinal dysbiosis occur in mice with hepatic fibrosis induced by CCl4 or bile duct ligation. Another study showed that ursolic acid (UA) attenuates experimental colitis via its anti-inflammatory and antioxidant activities. The goal of this study was to investigate the effects of UA on the intestinal mucosal barrier in CCl4-induced hepatic fibrosis in rats and identify its associated mechanisms. Male Sprague-Dawley rats were randomly divided into the following 3 groups (n = 10/group): the control, CCl4 model and UA treatment groups. Rats were sacrificed at 72 h after the hepatic fibrosis model was established and assessed for liver fibrosis, intestinal injury, enterocyte apoptosis, bacterial translocation, system inflammation, intestinal oxidative stress, and tight junction protein and NOX protein expression. The results demonstrated that UA attenuated the following: (i) liver and intestinal pathological injury; (ii) cleaved caspase-3 expression in the ileal epithelial cells; (iii) serum lipopolysaccharide and procalcitonin levels; (iv) intestinal malondialdehyde levels; and (v) the expression of the NOX protein components NOX2 and P67phox in ileal tissues. Furthermore, our results suggested that UA improved intestinal dysbiosis and the expression of the tight junction proteins Claudin 1 and Occludin in the ileum of rats. These results indicate that UA has protective effects on the intestinal mucosal barrier in rats with CCl4-induced liver fibrosis by inhibiting intestinal NOX-mediated oxidative stress. Our findings may provide a basis for further clinical studies of UA as a novel and adjuvant treatment to cure liver fibrosis.

Probiotics isolated from yaks improves the growth performance, antioxidant activity, and cytokines related to immunity and inflammation in mice

BACKGROUND

Yaks living in the high-altitude hypoxic environment of Tibetan plateau (3600 m) have special gut microbes. However, it is still little research on yak probiotics until now. Therefore, the purpose of our study was to evaluate the growth promoting effect, antioxidant capability, immune effect, and anti-inflammatory ability of Bacillus subtilis and Bacillus velezensis isolated from Tibetan yaks in mice model.

RESULTS

The results showed that the isolated strains supplementation not only improve the growth performance but also increased the length of villus in the small intestine and intestinal digestive enzyme activity. Importantly, we observed that the T-AOC, SOD, and GSH-PX levels were increased and the MDA content was reduced in probiotic-treated mice, which implied that probiotics supplementation can ameliorate the antioxidative activity of mice. The levels of AST and ALT correlated with the hepatic injury were reduced and the levels of AKP, TP, GLB, ALB, Ca, and P were markedly higher than those in the control group. Additionally, mice treated with probiotics exhibited higher serum IgG, IgM and IgA, which can reflect the immune status to some extent. At the same time, the major pro-inflammatory factor TNF-α, IL-6, and IL-8 were down-regulated and the anti-inflammatory factor IL-10 was up-regulated compared with the control groups.

CONCLUSIONS

In conclusion, these results demonstrated that Bacillus subtilis and Bacillus velezensis supplementation can increase overall growth performance and ameliorate the blood parameters related to inflammation and immunity of mice.

New insights and therapeutic implication of gut microbiota in non-alcoholic fatty liver disease and its associated liver cancer

The gastrointestinal tract represents one of the largest interfaces between the host and environmental factors. It contains a vast and complex community of microbes, forming what is collectively known as the microbiota. This gut microbiota plays a pivotal role in the maintenance of health, and 'dysbiosis' of the gut microbiota, commonly considered as perturbation of microbiota diversity and composition, has been associated with intestinal and extra-intestinal diseases, including non-alcoholic fatty liver disease (NAFLD) and its associated hepatocellular carcinoma (NAFLD-HCC). In this review, we highlight microbiota dysbiosis and the microbiota-host interactions that link to the pathogenesis of NAFLD and NAFLD-HCC. We discuss the potential therapeutic implications of the gut microbiota in the progression of NAFLD-HCC.

Bacterial translocation in patients with liver cirrhosis: physiology, clinical consequences, and practical implications

The gut liver axis is an operative unit that works to protect the human body against potentially harmful substances and microorganisms, maintaining the homeostasis of the immune system. Liver cirrhosis profoundly alters this complex system. The intestine becomes more permeable allowing the translocation of bacteria, bacterial products and fragments into the portal circulation, triggering an abnormal local and systemic inflammatory response and a condition of perpetual immunologic alarm. This immune-inflammatory disorder related to dysbiosis is involved in the development of liver damage and liver cirrhosis complications and increases intestinal permeability in a vicious circle. Areas covered: The most relevant studies on bacterial translocation, the mechanism of intestinal barrier dysfunction and its consequences in patients with liver cirrhosis have been revised through a PubMed search. Data have been discussed with particular regard to their significance in clinical practice. Expert commentary: The assessment of bacterial translocation and intestinal permeability is not currently used in clinical practice but may be useful to stratify patients' prognosis.

Mosapride Stabilizes Intestinal Microbiota to Reduce Bacterial Translocation and Endotoxemia in CCl4-Induced Cirrhotic Rats

BACKGROUND

Impaired intestinal motility may lead to the disruption of gut microbiota equilibrium, which in turn facilitates bacterial translocation (BT) and endotoxemia in cirrhosis. We evaluated the influence of mosapride, a prokinetic agent, on BT and DNA fingerprints of gut microbiota in cirrhotic rats.

METHODS

A rat model of cirrhosis was set up via subcutaneous injection of carbon tetrachloride (CCl₄). The portal pressure, liver and intestinal damage, plasma endotoxin, BT, and intestinal transit rate (ITR) of cirrhotic rats were determined. Fecal DNA fingerprints were obtained by ERIC-PCR. The expressions of tight junction proteins were evaluated by western blotting.

RESULTS

Mosapride treatment to cirrhotic rats significantly reduced the plasma endotoxin level and incidence of BT, accompanied by increased ITR. Cirrhotic rats (including those treated with mosapride) suffered from BT exhibited significantly lower ITR than those who are free of BT. Pearson coefficient indicated a significant and negative correlation between the plasma endotoxin level and ITR. The genomic fingerprints of intestinal microbiota from the three groups fell into three distinctive clusters. In the mosapride-treated group, Shannon's index was remarkably increased compared to the model group. Significantly positive correlation was detected between Shannon's index and ITR. Mosapride did not improve hepatic and intestinal damages and ileal expressions of occludin and ZO-1.

CONCLUSIONS

Mosapride significantly increases intestinal motility in cirrhotic rats, thus to recover the disordered intestinal microbiota, finally resulting in decreased plasma endotoxin and BT.

Gut-liver axis, cirrhosis and portal hypertension: the chicken and the egg

The term gut-liver axis is used to highlight the close anatomical and functional relationship between the intestine and the liver. The intestine has a highly specialized epithelial membrane which regulates transport across the mucosa. Due to dysbiosis, impairment of the intestinal barrier and altered immunity status, bacterial products can reach the liver through the portal vein, where they are recognized by specific receptors, activate the immune system and lead to a proinflammatory response. Gut microbiota and bacterial translocation play an important role in the pathogenesis of chronic liver diseases, including alcoholic and non-alcoholic fatty liver disease, cirrhosis, and its complications, such as portal hypertension, spontaneous bacterial peritonitis and hepatic encephalopaty. The gut microbiota also plays a critical role as a modulator of bile acid metabolism which can also influence intestinal permeability and portal hypertension through the farnesoid-X receptor. On the other hand, cirrhosis and portal hypertension affect the microbiota and increase translocation, leading to a "chicken and egg" situation, where translocation increases portal pressure, and vice versa. A myriad of therapies targeting gut microbiota have been evaluated specifically in patients with chronic liver disease. Further studies targeting intestinal microbiota and its possible hemodynamic and metabolic effects are needed. This review summarizes the current knowledge about the role of gut microbiota in the pathogenesis of chronic liver diseases and portal hypertension.

Fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 reduces bacterial translocation in rats treated with carbon tetrachloride

Probiotics can prevent pathological bacterial translocation by modulating intestinal microbiota and improving the gut barrier. The aim was to evaluate the effect of a fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 on bacterial translocation in rats with carbon tetrachloride (CCl₄)-induced cirrhosis. Sprague-Dawley rats treated with CCl₄ were randomized into a probiotic group that received fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 in drinking water or a water group that received water only. Laparotomy was performed one week after ascites development. We evaluated bacterial translocation, intestinal microbiota, the intestinal barrier and cytokines in mesenteric lymph nodes and serum. Bacterial translocation decreased and gut dysbiosis improved in the probiotic group compared to the water group. The ileal β-defensin-1 concentration was higher and ileal malondialdehyde levels were lower in the probiotic group than in water group. There were no differences between groups in serum cytokines but TNF-α levels in mesenteric lymph nodes were lower in the probiotic group than in the water group. Fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 decreases bacterial translocation, gut dysbiosis and ileal oxidative damage and increases ileal β-defensin-1 expression in rats treated with CCl₄, suggesting an improvement in the intestinal barrier integrity.

Is intestinal oxidative stress involved in patients with compensated liver cirrhosis?

BACKGROUND

Liver cirrhosis is associated with intestinal epithelial barrier dysfunction, which may be affected by oxidative stress. Studies in cirrhotic rats provided evidence for intestinal oxidative stress, but studies in cirrhotic patients are scarce. We have shown intestinal barrier dysfunction in patients with compensated cirrhosis.

AIM

The present study aimed to investigate whether oxidative stress occurs in the intestinal mucosa of compensated cirrhotic patients and may contribute to barrier dysfunction.

MATERIAL AND METHODS

Oxidative stress was studied in duodenal and sigmoid biopsies from 15 cirrhotic patients and 22 controls by analyzing transcription of genes involved in glutathione and uric acid metabolism using quantitative real-time polymerase chain reaction. Protein levels of glutathione and glutathione disulphide were measured and the glutathione/glutathione disulphide ratio was calculated as marker of oxidative stress. In addition, intestinal myeloperoxidase and fecal calprotectin were determined.

RESULTS

Gene transcription of glutathione synthetase and glutathione reductase were significantly different in duodenal and sigmoid biopsies of cirrhotic patients vs. controls, but no alterations were found for other genes nor for glutathione, glutathione disulphide, glutathione/glutathione disulphide ratio and intestinal myeloperoxidase and fecal calprotectin concentrations.

CONCLUSION

This study did not find indications for oxidative stress and low-grade inflammation in the small and large intestine of stable compensated cirrhotic patients. Although these preliminary findings need further validation, we found intestinal oxidative stress not to be a major mechanism contributing to epithelial barrier dysfunction in patients with compensated cirrhosis.

Effect of long-term acid gastric inhibition on bacterial translocation in cirrhotic rats

BACKGROUND

Bacterial translocation (BT) related to intestinal bacterial overgrowth (IBO) plays an important role in the pathogenesis of bacterial infections in cirrhosis. Inhibition of acid gastric secretion promotes IBO and might favor BT. We evaluated the effect of long-term inhibition of acid gastric secretion on BT in cirrhotic rats.

METHODS

Cirrhotic rats with and without ascites induced by oral CCl4 and controls were randomized to treatment with a daily subcutaneous injection of placebo, ranitidine (50 mg/kg), or pantoprazole (8 mg/kg) during 2 weeks. Continuous pH-metry was performed for 2 h before and at the end of treatment; thereafter, a laparotomy to obtain samples of blood, mesenteric lymph nodes, ascites, spleen, liver, and cecal stools was performed.

RESULTS

Ranitidine and pantoprazole increased gastric pH as compared with placebo (P<0.001). However, antisecretory drugs increased the incidence of BT only in ascitic rats treated with ranitidine (P<0.05) or pantoprazole (P=0.07) when compared with placebo-treated ascitic rats or cirrhotic rats without ascites treated with the same drug. Cirrhotic ascitic rats treated with pantoprazole showed a trend toward an increased incidence of IBO (P=0.08), a higher ileal malondialdehyde level (P<0.01), and an increased production of tumor necrosis factor-α (P<0.05).

CONCLUSION

Although inhibition of acid gastric secretion increased gastric pH in all animals, the incidence of BT increased only in ascitic rats, and it was associated with a trend toward an increase in IBO incidence, a higher ileal malondialdehyde level, and an increased production of serum tumor necrosis factor-α. Therefore, antisecretory drugs should be carefully administered to cirrhotic ascitic patients.

VSL#3 probiotic treatment decreases bacterial translocation in rats with carbon tetrachloride-induced cirrhosis

BACKGROUND & AIMS

Probiotics can prevent pathological bacterial translocation in cirrhosis by modulating intestinal microbiota and improving gut barrier and immune disturbances. To evaluate the effect of probiotic VSL#3 on bacterial translocation, intestinal microbiota, gut barrier and inflammatory response in rats with experimental cirrhosis.

METHODS

Forty-six Sprague-Dawley rats with CCl4 -induced cirrhosis were randomized into two groups: VSL#3 group (n = 22) that received VSL#3 in drinking water, and water group (n = 24) that received water only. Treatment began at week 6 of cirrhosis induction and continued until laparotomy, performed 1 week after development of ascites or at week 20. A control group included 11 healthy rats. At this study end, we evaluated bacterial translocation, intestinal flora, intestinal barrier (ileal claudin-2 and 4, β-defensin-1, occludin and malondialdehyde as index of oxidative damage) and serum cytokines.

RESULTS

Mortality during this study was similar in the VSL#3 group (10/22, 45%) and the water group (10/24, 42%) (P = 1). The incidence of bacterial translocation was 1/12 (8%) in the VSL#3 group, 7/14 (50%) in the water group (P = 0.03 vs. VSL#3 group) and 0/11 in the control group (P = 0.008 vs. water group). The concentration of ileal and caecal enterobacteria and enterococci was similar in the two groups of cirrhotic rats. The ileal occludin concentration was higher and ileal malondialdehyde and serum levels of TNF-α were lower in the VSL#3 group than in the water group (P < 0.05).

CONCLUSIONS

VSL#3 decreases bacterial translocation, the pro-inflammatory state and ileal oxidative damage and increases ileal occludin expression in rats with experimental cirrhosis.

Ascites and spontaneous bacterial peritonitis: recommendations from two United States centers

Cirrhosis affects millions of people throughout the world. Two of the most serious complications of liver cirrhosis are ascites and spontaneous bacterial peritonitis (SBP). The development of ascites is related to the severity of portal hypertension and is an indicator of increased mortality. Although sodium restriction and diuretic therapy have proven effective, some patients may not respond appropriately or develop adverse reactions to diuretic therapy. In such cases, interventions such as transjugular intrahepatic portosystemic shunt (TIPS) placement are warranted. SBP is a complication of ascites that confers a very high mortality rate. Recognition and prompt treatment of this condition is essential to prevent serious morbidity and mortality. Initiation of prophylaxis in SBP remains controversial. Given the burden of liver cirrhosis on the health care system, ascites and SBP will continue to provide challenges for the primary care provider, hospitalist, internist, and gastroenterologist alike.

Intestinal epithelial barrier function in liver cirrhosis: an extensive review of the literature

Recent evidence suggests that translocation of bacteria and bacterial products, such as endotoxin from the intestinal lumen into the systemic circulation is a contributing factor in the pathogenesis of chronic liver diseases and the development of complications in cirrhosis. In addition to alterations in the intestinal microbiota and immune system, dysfunction of the intestinal epithelial barrier may be an important factor facilitating bacterial translocation. This review aims to provide an overview of the current evidence of intestinal epithelial barrier dysfunction in human chronic liver diseases and cirrhosis, and to discuss possible contributing factors and mechanisms. Data suggest the presence of intestinal epithelial barrier dysfunction in patients with chronic liver diseases, but are more convincing in patients with cirrhosis, especially in those with complications. The barrier dysfunction can result from both direct and indirect effects of aetiological factors, such as alcohol and obesity, which can cause chronic liver diseases and ultimately cirrhosis. On the other hand characteristics of cirrhosis itself, including portal hypertension, alterations in the intestinal microbiota, inflammation and oxidative stress can affect barrier function of both small and large intestine and may contribute to the development of complications. In conclusion, there are indications for intestinal epithelial barrier dysfunction in patients with chronic liver diseases and especially in patients with cirrhosis, which can be caused by various factors affecting both the small and large intestine.

The role of gut-liver axis in the pathogenesis of liver cirrhosis and portal hypertension

Because of the anatomical position and its unique vascular system, the liver is susceptible to the exposure to the microbial products from the gut. Although large amount of microbes colonize in the gut, translocation of the microbes or microbial products into the liver and systemic circulation is prevented by gut epithelial barrier function and cleansing and detoxifying functions of the liver in healthy subjects. However, when the intestinal barrier function is disrupted, large amount of bacterial products can enter into the liver and systemic circulation and induce inflammation through their receptors. Nowadays, there have been various reports suggesting the role of gut flora and bacterial translocation in the pathogenesis of chronic liver disease and portal hypertension. This review summarizes the current knowledge about bacterial translocation and its contribution to the pathogenesis of chronic liver diseases and portal hypertension.

Reduction of intestinal mucosal immune function in heat-stressed rats and bacterial translocation

PURPOSE

The aim of this study was to further understand the effects and mechanism of heat stress on the intestinal mucosal immune system of the rat, including changes in the intestinal mucosal barrier and immune function and their effects on bacterial translocation.

MATERIALS AND METHODS

Sprague Dawley (SD) rats were randomly divided into control and heat-stress groups. Both groups were housed in a 25°C environment of 60% relative humidity. The heat-stress group was subjected to 40°C for 2 h daily over 3 days.

RESULTS

Compared with the control group villi length in the small intestines of the heat-stress group was shortened. Jejunal mucosa were seriously damaged and the number of goblet cells in the epithelia of the duodenum and jejunum was significantly reduced. Electron microscopy revealed intestinal mucosal disorder, a large number of exudates of inflammatory fibrous material, fuzzy tight junction structure between epithelial cells, and cell gap increases in the heat-stress group. Transcription of IFN-γ, IL-2, IL-4, and IL-10, was significantly reduced, as was that of the intestinal mucosal immune-related proteins TLR2, TLR4, and IgA. The number of CD3(+) T cells and CD3(+)CD4(+)CD8(-) T cells in the mesenteric lymph nodes (MLNs) was significantly lower, while the number of CD3(+)CD4(-)CD8(+) T cells was significantly increased. The bacteria isolated from the MLNs were Escherichia coli.

CONCLUSIONS

Heat stress damages rat intestinal mechanical and mucosal immune barriers, and reduces immune function of the intestinal mucosa and mesenteric lymphoid tissues, leading to bacterial translocation.

Microbial translocation in chronic liver diseases

The intestinal microflora is not only involved in the digestion of nutrients, but also in local immunity, forming a barrier against pathogenic microorganisms. The derangement of the gut microflora may lead to microbial translocation, defined as the passage of viable microorganisms or bacterial products (i.e., LPS, lipopeptides) from the intestinal lumen to the mesenteric lymph nodes and other extraintestinal sites. The most recent evidence suggests that microbial translocation (MT) may occur not only in cirrhosis, but also in the early stage of several liver diseases, including alcoholic hepatopathy and nonalcoholic fatty liver disease. Different mechanisms, such as small intestinal bacterial overgrowth, increased permeability of intestinal mucosa, and impaired immunity, may favor MT. Furthermore, MT has been implicated in the pathogenesis of the complications of cirrhosis, which are a significant cause of morbidity and mortality in cirrhotic subjects. Therapeutic strategies aiming at modulating the gut microflora and reducing MT have focused on antibiotic-based options, such as selective intestinal decontamination, and nonantibiotic-based options, such as prokinetics and probiotics. In particular, probiotics may represent an attractive strategy, even though the promising results of experimental models and limited clinical studies need to be confirmed in larger randomized trials.

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

BACKGROUND

Prophylaxis 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 CCl(4)-induced cirrhosis and ascites.

METHOD

After development of cirrhosis and ascites, animals were randomly allocated to receive pentoxifylline (16 mg/kg/d every 8h, oral route, n=13) or placebo (n=12) for 15 days. An additional group of 8 cirrhotic rats was given norfloxacin (5mg/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.

RESULTS

Pentoxifylline 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).

CONCLUSION

In 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.

Different clinical characteristics among Aeromonas hydrophila, Aeromonas veronii biovar sobria and Aeromonas caviae monomicrobial bacteremia

This study aimed to compare the clinical presentations of Aeromonas hydrophila, A. veronii biovar sobria and A. caviae monomicrobial bacteremia by a retrospective method at three hospitals in Taiwan during an 8-yr period. There were 87 patients with A. hydrophila bacteremia, 45 with A. veronii biovar sobria bacteremia and 22 with A. caviae bacteremia. Compared with A. hydrophila and A. veronii biovar sobria bacteremia, A. caviae bacteremia was more healthcare-associated (45 vs 30 and 16%; P = 0.031). The patients with A. caviae bacteremias were less likely to have liver cirrhosis (27 vs 62 and 64%; P = 0.007) and severe complications such as shock (9 vs 40 and 47%; P = 0.009) and thrombocytopenia (45 vs 67 and 87%; P = 0.002). The APACHE II score was the most important risk factor of Aeromonas bacteremia-associated mortalities. The APACHE II scores of A. caviae bacteremias were lower than A. hydrophila bacteremia and A. veronii biovar sobria bacteremia (7 vs 14 and 16 points; P = 0.002). In conclusion, the clinical presentation of A. caviae bacteremia was much different from A. hydrophila and A. veronii biovar sobria bacteremia. The severity and mortality of A. caviae bacteremia were lower than A. hydrophila or A. veronii biovar sobria bacteremia.

Bacterial DNA in the diagnosis of spontaneous bacterial peritonitis

BACKGROUND

Despite inoculation into blood culture bottles, ascitic fluid culture is negative in 50% of cases of spontaneous bacterial peritonitis (SBP).

AIM

To determine whether 16S rDNA gene detection by real-time polymerase chain reaction (PCR) and sequencing increases the efficacy of culture in microbiological diagnosis of spontaneous bacterial peritonitis.

METHODS

We prospectively included 55 consecutive spontaneous bacterial peritonitis episodes in cirrhotic patients, 20 cirrhotic patients with sterile ascites and 27 patients with neoplasic ascites. Ascitic fluid was inoculated into blood culture bottles at the bedside and tested for bacterial DNA by real-time PCR and sequencing of 16S rDNA gene.

RESULTS

Bacterial DNA was detected in 23/25 (92%) culture-positive SBP, 16/30 (53%) culture-negative SBP (P = 0.002 with respect to culture-positive SBP), 12/20 (60%) sterile ascites (P = 0.01 with respect to culture-positive SBP) and 0/27 neoplasic ascites (P < 0.001 with respect to other groups). Sequencing identified to genus or species level 12 culture-positive SBP, six culture-negative SBP and six sterile ascites. In the remaining cases with positive PCR, sequencing did not yield a definitive bacterial identification.

CONCLUSIONS

Bacterial DNA was not detected in almost half the culture-negative spontaneous bacterial peritonitis episodes. Methodology used in the present study did not always allow identification of amplified bacterial DNA.

iNOS expression in vascular resident macrophages contributes to circulatory dysfunction of splanchnic vascular smooth muscle contractions in portal hypertensive rats

Portal hypertension, a major complication of cirrhosis, is caused by both increased portal blood flow due to arterial vasodilation and augmented intrahepatic vascular resistance due to sinusoidal constriction. In this study, we examined the possible involvement of resident macrophages in the tone regulation of splanchnic blood vessels using bile duct ligated (BDL) portal hypertensive rats and an in vitro organ culture method. In BDL cirrhosis, the number of ED2-positive resident macrophages increased by two- to fourfold in the vascular walls of the mesenteric artery and extrahepatic portal vein compared with those in sham-operated rats. Many ED1-positive monocytes were also recruited into this area. The expression of inducible nitric oxide (NO) synthase (iNOS) mRNA was increased in the vascular tissues isolated from BDL rats, and accordingly, nitrate/nitrite production was increased. Immunohistochemistry revealed that iNOS was largely expressed in ED1-positive and ED2-positive cells. We further analyzed the effect of iNOS expression on vascular smooth muscle contraction using an in vitro organ culture system. iNOS mRNA expression and nitrate production significantly increased in vascular tissues (without endothelium) incubated with 1 μg/ml lipopolysaccharide (LPS) for 6 h. Immunohistochemistry indicated that iNOS was largely expressed in ED2-positive resident macrophages. α-Adrenergic-stimulated contractility of the mesenteric artery was greatly suppressed by LPS treatment and was restored by N(G)-nitro-L-arginine methyl ester (NO synthase inhibitor); in contrast, portal vein contractility was largely unaffected by LPS. Sodium nitroprusside (NO donor) and 8-bromo-cGMP showed greater contractile inhibition in the mesenteric artery than in the portal vein with decreasing myosin light chain phosphorylation. In the presence of an α-adrenergic agonist, the mesenteric artery cytosolic Ca(2+) level was greatly reduced by sodium nitroprusside; however, the portal vein Ca(2+) level was largely unaffected. These results suggest that the induction of iNOS in monocytes/macrophages contributes to a hypercirculatory state in the cirrhosis model rat in which the imbalance of the responsiveness of visceral vascular walls to NO (mesenteric artery >> portal vein) may account for the increased portal venous flow in portal hypertension.

Decreased IgA+ plasma cells and IgA expression in acute liver necrosis mice

AIM: To investigate the number of intestinal immunoglobulin A (IgA+) plasma cells and expression of intestinal IgA in mice with acute liver necrosis.

METHODS: A model of acute liver necrosis was established by intraperitoneal injection of galactosamine (GalN) and lipopolysaccharide (LPS). Sixty mice were randomly divided into one of 4 equal groups: normal control, acute liver necrosis, LPS, or GalN. Hematoxylin and eosin staining, immunohistochemistry, and an enzyme-linked immunosorbent assay were employed to assess liver and intestinal injury, count intestinal IgA+ plasma cells, and measure the expression level of IgA and interferon γ (IFN-γ) in the small intestinal mucosa of mice.

RESULTS: Injured intestinal mucosa was observed in the acute liver necrosis group but not in the normal, LPS or GalN groups. Compared with the normal group, intestinal IgA+ plasma cells were slightly decreased in the LPS and GalN groups [429 ± 20 per high power field (HPF), 406 ± 18/HPF, respectively], whereas they were markedly decreased in the acute liver necrosis group (282 ± 17/HPF vs 495 ± 26/HPF in normal group, P < 0.05). The expression of intestinal IgA was also slightly decreased in LPS and GalN groups, but was markedly reduced in the acute liver necrosis group as determined by enzyme-linked immunosorbent assay (P < 0.05). In contrast, the level of IFN-γ was slightly increased in LPS, GalN and acute liver necrosis groups, but with no statistical significance (P > 0.05).

CONCLUSION: Intestinal IgA+ plasma cells and IgA expression levels indicating that mucosal immune barrier dysfunction, does exist in acute liver necrosis.

Bacterial translocation to mesenteric lymph nodes increases in chronic portal hypertensive rats

PURPOSE

Bacterial translocation is a frequent complication in portal hypertension related to cirrhosis in the human clinical area. The aim of this study was to verify the existence of intestinal bacterial translocation to mesenteric lymph nodes in male Wistar rats with triple partial portal vein ligation during short- (48 h) and long-term (1 month) postoperative evolution.

RESULTS

At 48 h, ileal total aerobes bacteria (p < 0.001) and Lactobacillus decrease in sham-operated (SO) and portal hypertensive (PH) rats. At 1 month, ileal Enterococci and Streptococcus sp. show a statistically significant decrease in SO- and PH-rats. Lactobacillus decreases in the colon in SO- (p < 0.01) and in PH-rats (p < 0.001). At 1 month, colonic Enterococci decreases compared to control (p < 0.001) and SO-rats (p < 0.01). These intestinal microfloral changes are associated with bacterial translocation to mesenteric lymph nodes at 48 h (50%; p = 0.004) and 1 month (100%; p < 0.001) of postoperative evolution in PH-rats.

CONCLUSIONS

The enlargement of the stenosed portal tract related to triple partial portal vein ligation in the rat, since it increases the resistance to the portal blood flow, may be a key factor involved in one of the pathological consequences of portal hypertension, as is bacterial translocation to mesenteric lymph nodes.

Z-FA.FMK activates duodenal epithelial cell proliferation through oxidative stress, NF-kappaB and IL-1beta in D-GalN/TNF-alpha-administered mice

This study was designed to evaluate the effect of Z-FA.FMK (benzyloxycarbonyl-l-phenylalanyl-alanine-fluoromethylketone), a pharmacological inhibitor of cathepsin B, on the proliferation of duodenal mucosal epithelial cells and the cellular system that controls this mechanism in these cells in vivo. For this investigation, BALB/c male mice were divided into four groups. The first group received physiological saline, the second group was administered Z-FA.FMK, the third group received D-GalN (D-galactosamine) and TNF-alpha (tumour necrosis factor-alpha) and the fourth group was given both D-GalN/TNF-alpha and Z-FA.FMK. When D-GalN/TNF-alpha was administered alone, we observed an increase in IL-1beta-positive and active NF-kappaB-positive duodenal epithelial cells, a decrease in PCNA (proliferative cell nuclear antigen)-positive duodenal epithelial cells and an increase in degenerative changes in duodenum. On the other hand, Z-FA.FMK pretreatment inhibited all of these changes. Furthermore, lipid peroxidation, protein carbonyl and collagen levels were increased, glutathione level and superoxide dismutase activity were decreased, while there was no change in catalase activity by D-GalN/TNF-alpha injection. On the contrary, the Z-FA.FMK pretreatment before D-GalN/TNF-alpha blocked these effects. Based on these findings, we suggest that Z-FA.FMK might act as a proliferative mediator which is controlled by IL-1beta through NF-kappaB and oxidative stress in duodenal epithelial cells of D-GalN/TNF-alpha-administered mice.

Different clinical characteristics between polymicrobial and monomicrobial Aeromonas bacteremia--a study of 216 cases

BACKGROUND

Part of Aeromonas bacteremia is polymicrobial infection. However, a clinical comparison of monomicrobial and polymicrobial Aeromonas bacteremia has not hitherto been reported.

METHODS

A retrospective analysis of medical records of patients with Aeromonas bacteremia at three large referral hospitals in Taiwan for an 8-year period (2001-2008) was conducted.

RESULTS

There were 154 patients with monomicrobial Aeromonas bacteremia and 62 patients with polymicrobial Aeromonas bacteremia. In the polymicrobial infections, E. coli was the most common combined pathogen (42%), followed by Klebsiella spp. (24%) and Enterobacter spp. (16%). Multivariate logistic regression analysis revealed solid cancer as the risk factor for polymicrobial Aeromonas bacteremia, with male gender and cirrhosis as risk factors for monomicrobial Aeromonas bacteremia. However, of all types of solid cancer, hepatoma was associated with monomicrobial Aeromonas bacteremia. APACHE II score was the most important prognostic factor in both groups.

CONCLUSION

Aeromonas bacteremia in patients with cirrhosis or male gender tended to be monomicrobial. Polymicrobial Aeromonas bacteremia was associated with solid cancers. In either polymicrobial or monomicrobial Aeromonas bacteremia, prognosis could be predicted according to disease severity measured by APACHE II score.

Spontaneous bacterial peritonitis

Since its initial description in 1964, research has transformed spontaneous bacterial peritonitis (SBP) from a feared disease (with reported mortality of 90%) to a treatable complication of decompensated cirrhosis, albeit with steady prevalence and a high recurrence rate. Bacterial translocation, the key mechanism in the pathogenesis of SBP, is only possible because of the concurrent failure of defensive mechanisms in cirrhosis. Variants of SBP should be treated. Leucocyte esterase reagent strips have managed to shorten the ‘tap-to-shot’ time, while future studies should look into their combined use with ascitic fluid pH. Third generation cephalosporins are the antibiotic of choice because they have a number of advantages. Renal dysfunction has been shown to be an independent predictor of mortality in patients with SBP. Albumin is felt to reduce the risk of renal impairment by improving effective intravascular volume, and by helping to bind pro-inflammatory molecules. Following a single episode of SBP, patients should have long-term antibiotic prophylaxis and be considered for liver transplantation.

Association of liver cirrhosis related IgA nephropathy with portal hypertension

A high incidence of IgA nephropathy has been reported in patients with liver cirrhosis, though, clinically evident nephrotic syndrome is very uncommon. Impaired hepatic clearance of circulating IgA immune complexes and subsequent deposition in renal glomeruli has been considered principally in the pathogenesis of liver cirrhosis associated IgA nephropathy. Here we report on a patient with cryptogenic liver cirrhosis and splenic vein thrombosis, who presented with nephrotic syndrome. Renal biopsy showed findings consistent with IgA nephropathy. Lower endoscopy showed features of portal hypertensive colopathy. Following initiation of propranolol and anticoagulant treatment to reduce portal pressure, a gradual decrease of proteinuria and hematuria to normal range was noted. The potential pathogenetic role of portal hypertension in the development of IgA nephropathy in cirrhotic patients is discussed.

Decreased leukocyte recruitment in the mesenteric microcirculation of rats with cirrhosis is partially restored by treatment with peginterferon: an in vivo study

BACKGROUND/AIMS

Patients with liver cirrhosis are predisposed to develop bacterial infections. An essential process in inflammatory responses is the recruitment of circulating leukocytes through the activation of adhesion molecules. Interferon-alpha2a is a cytokine reported to influence the expression of adhesion molecules. We investigated the effect of peginterferon-alpha2a (PegIFN-alpha(2a)) in vivo on the leukocyte recruitment in the mesenteric microcirculation of cirrhotic rats after lipopolysaccharide exposure.

METHODS

Leukocyte rolling, adhesion and extravasation were visualized by intravital microscopy in sham-operated and common bile duct ligated (CBDL) rats. PegIFN-alpha(2a) was administered to influence leukocyte recruitment. Endothelial P-selectin, E-selectin and ICAM-1 expression were studied by immunohistochemistry.

RESULTS

CBDL placebo rats showed significantly impaired rolling, adhesion and extravasation of leukocytes compared to Sham-operated placebo rats. Endothelial P-selectin, E-selectin and ICAM-1 expressions in CBDL placebo rats were significantly reduced compared to Sham-operated placebo rats. PegIFN-alpha(2a) 18 microg normalized number of rolling leukocytes in CBDL rats, without influencing on adhering and extravasated leukocytes. PegIFN-alpha(2a) upregulates the expression of P-selectin and E-selectin in CBDL rats, but ICAM-1 expression remained significantly lower than in Sham rats.

CONCLUSIONS

Leukocyte recruitment is significantly impaired in the mesenteric microcirculation of cirrhotic rats. This deficiency appears to result from a reduced endothelial P-selectin, E-selectin and ICAM-1 expression. Peginterferon-alpha(2a) treatment normalizes rolling of leukocytes in cirrhotic rats by upregulation of P-selectin and E-selectin expressions, but has no influence on adhesion and extravasation possibly due to the absence of effect on ICAM-1 expression.

Amplification of bacterial DNA does not distinguish patients with ascitic fluid infection from those colonized by bacteria

OBJECTIVE

To evaluate 16S ribosomal RNA (rRNA) gene amplification to diagnose spontaneous bacterial peritonitis (SBP).

PATIENTS AND METHODS

According to a retrospective protocol, 31 patients with portal hypertensive ascites (serum to ascites albumin gradient > or = 1.1 g/dL) were studied. Ascitic fluid was analyzed as follows: Gram stain, aerobic and anaerobic cultures, polymorphonuclear cell count, and biochemical tests. Bacterial DNA was detected by polymerase chain reaction.

RESULTS

There were 8 episodes of SBP and 4 episodes of bacterascites (BA). Culture was positive in 4 of 8 cases of SBP and bacterial DNA was positive in 7 of 8 cases of SBP. Bacterial DNA was positive in 3 of 4 cases of BA and in 8 of 28 cases of culture-negative non-neutrocytic ascites (CNNNA). The PELD score, serum to albumin ascites gradient, and mortality showed no statistical difference between patients with CNNNA and the result of the bacterial DNA analysis.

CONCLUSIONS

Although the 16S rRNA gene amplification was better than culture to diagnose SBP, bacterial DNA does not seem to allow a distinction between ascites infection and ascites colonization.

Bacterial translocation is downregulated by anti-TNF-alpha monoclonal antibody administration in rats with cirrhosis and ascites

BACKGROUND/AIMS

TNF-alpha is involved in the development of bacterial translocation in rats with cirrhosis. The aim of the current study was to evaluate the effect of anti-TNF-alpha mAb treatment on the incidence of bacterial translocation and systemic infections in rats with cirrhosis and ascites.

METHODS

Thirty rats with cirrhosis and ascites were randomly assigned to receive two intraperitoneal doses of anti-TNF-alpha mAb, distilled water or immunoglobulin on days 0 and 4. On day 10, a laparotomy was performed.

RESULTS

One out of 11 animals receiving anti-TNF-alpha mAb treatment, 7 out of 10 of the placebo group (p<0.01), and 5 out of 9 of the IgG group developed bacterial translocation (p<0.05). A significantly reduced number of systemic infections were observed in animals receiving anti TNF-alpha mAb treatment vs animals receiving placebo (p<0.01). TNF-alpha in serum at laparotomy in animals receiving anti-TNF-alpha mAb was higher than that in the rest of groups and was also higher in the overall series of animals showing bacterial translocation.

CONCLUSIONS

In the experimental model of CCl(4)-induced rat with cirrhosis and ascitic fluid, anti-TNF-alpha mAb administration decreases the incidence of bacterial translocation, in a TNF-alpha/sTNF-alpha receptor-independent manner, without increasing the risk of systemic infections.

Clinical significance of Toll-like receptor 4 and 2 expression on the surface of peripheral blood mononuclear cells in patients with liver cirrhosis

AIM: To explore the correlation of Toll-like receptor 4, Toll-like receptors 2 expression on the surface of peripheral blood mononuclear cells with bacterial infection in patients with liver cirrhosis, and observe the effect of antibiotics on PBMC expression of TLR4 and TLR2 in cirrhosis.

METHODS: Blood cells from a total of 42 patients (30 with ascites, 12 without ascites) with liver cirrhosis and 15 normal controls were stained with fluorescent labeling anti-TLR2/anti-TLR4/anti-CD14 monoclonal antibodies. Samples were collected and analyzed for three-color immunofluorescence by flow cytometry.

RESULTS: The expression of TLR4 and TLR2 were significantly higher in patients with ascites than those in the controls (TLR4: 22.28 ± 0.80 vs 14.45 ± 3.23, P < 0.05; TLR2: 47.65 ± 0.75 vs 24.40 ± 2.77, P < 0.05), and marked difference also existed before and after treatment (TLR4: 28.58 ± 0.79 vs 12.37 ± 0.35, P < 0.05; TLR2: 47.79 ± 0.76 vs 17.22 ± 2.48, P < 0.05). TLR4 and TLR2 expression were notably increased in patients with ascites as compared with those in ones without ascites (TLR2: 25.37 ± 1.62; TLR4: 14.81 ± 0.29) (P < 0.05), and they were not significantly different between patients without ascites and normal controls (P > 0.05).

CONCLUSION: PBMC expression of TLR4 and TLR2 are up-regulated in patients with liver cirrhosis, and they can be down-regulated by antibiotics treatment.

The effect of caffeic acid phenethyl ester on bacterial translocation and intestinal damage in cholestatic rats

We investigated the effect of caffeic acid phenethyl ester in rat ileum injury induced by chronic biliary obstruction. Swiss albino rats were divided into three groups: Group 1, sham (n = 7); Group 2, common bile duct ligation (n = 7); and Group 3, common bile duct ligation plus caffeic acid phenethyl ester (n = 7). In the caffeic acid phenethyl ester-treated rats, ileum tissue levels of malondialdehyde and myeloperoxidase were significantly lower than those of the bile duct-ligated rats (P < 0.001). The levels of tumor necrosis factor-alpha, interleukin-6, and interleukin-1alpha in the caffeic acid phenethyl ester group were significantly lower than those in the bile duct ligation group (P < 0.03, P < 0.01, and P < 0.02 respectively). The present study demonstrates that intraperitoneal administration of caffeic acid phenethyl ester in bile duct-ligated rats reduces intestinal oxidative stress. This effect may be useful in the preservation of intestinal damage in cholestasis.