The detection of bacterial DNA in blood of rats with CCl4-induced cirrhosis with ascites represents episodes of bacterial translocation

Bacterial translocation occurs early in cirrhosis and triggers a selective inflammatory response

BACKGROUND

Experimental data suggest that bacterial translocation (BT) promotes systemic inflammation, portal hypertension, and circulatory dysfunction in advanced chronic liver disease (ACLD).

METHODS

Patients with ACLD undergoing hepatic venous pressure gradient (HVPG) measurement and absence of acute decompensation or infections were included (n = 249). Serum biomarkers of BT (lipopolysaccharide [LPS], lipoteichoic acid [LTA], bacterial DNA [bactDNA]), systemic inflammation and markers of circulatory dysfunction were assessed. T-cell subsets in intestinal biopsies (n = 7 ACLD, n = 4 controls) were analyzed by flow cytometry.

RESULTS

Patients had a median HVPG of 18 (12-21) mmHg and 56% had decompensated ACLD. LPS (0.04 [0.02-0.06] vs. 0.64 [0.30-1.06] EU/mL), LTA (4.53 [3.58-5.97] vs. 43.2 [23.2-109] pg/mL), and detection of bactDNA (≥ 5 pg/mL; 5% vs. 41%) were markedly higher in patients with ACLD than healthy controls (n = 40; p < 0.001) but were similar between different clinical stages of compensated and decompensated ACLD and displayed no meaningful correlation with HVPG and systemic hemodynamics. TNF-α and IL-10 correlated with LPS (Spearman's rs = 0.523, p < 0.001/rs = 0.143, p = 0.024) but not with LTA. Presence of bactDNA was associated with higher LPS (0.54 [0.28-0.95] vs. 0.88 [0.32-1.31] EU/mL, p = 0.001) and TNF-α (15.3 [6.31-28.1] vs. 20.9 [13.8-32.9] pg/mL). Patients with ACLD exhibited a decreased CD4:CD8-ratio and increased TH1-cells in the intestinal mucosa as compared to controls. During a median FU of 14.7 (8.20-26.5) months, bacterial antigens did not predict decompensation or liver-related death (in contrast to HVPG, IL-6, and MAP) as well as infections at 24 months.

CONCLUSION

BT occurs already in early ACLD stages and triggers a systemic inflammatory response via TNF-α and IL-10. Interestingly, BT markers showed no clear correlation with portal hypertension and circulatory dysfunction in patients with stable ACLD.

CLINICAL TRIAL NUMBER

NCT03267615.

Is it possible to intervene early cirrhosis by targeting toll-like receptors to rebalance the intestinal microbiome?

Cirrhosis is a progressive chronic liver disease caused by one or more causes and characterized by diffuse fibrosis, pseudolobules, and regenerated nodules. Once progression to hepatic decompensation, the function of the liver and other organs is impaired and almost impossible to reverse and recover, which often results in hospitalization, impaired quality of life, and high mortality. However, in the early stage of cirrhosis, there seems to be a possibility of cirrhosis reversal. The development of cirrhosis is related to the intestinal microbiota and activation of toll-like receptors (TLRs) pathways, which could regulate cell proliferation, apoptosis, expression of the hepatomitogen epiregulin, and liver inflammation. Targeting regulation of intestinal microbiota and TLRs pathways could affect the occurrence and development of cirrhosis and its complications. In this paper, we first reviewed the dynamic change of intestinal microbiota and TLRs during cirrhosis progression. And further discussed the interaction between them and potential therapeutic targets to reverse early staged cirrhosis.

Systemic inflammation is linked to liver fibrogenesis in patients with advanced chronic liver disease

BACKGROUND & AIMS

Experimental evidence indicates that systemic inflammation (SI) promotes liver fibrogenesis. This study investigated the potential link between SI and fibrogenesis in patients with advanced chronic liver disease (ACLD).

METHODS

Serum biomarkers of SI (CRP, IL-6, procalcitonin [PCT]) and extracellular matrix (ECM) turnover (i.e., fibrogenesis/fibrolysis) were analysed in 215 prospectively recruited patients with ACLD (hepatic venous pressure gradient [HVPG] ≥6 mm Hg) undergoing hepatic vein catheterization. Patients with non-elective hospitalization or bacterial infection were excluded. Histological alpha-smooth muscle actin (α-SMA) area was quantified on full biopsy scans by automated morphometric quantification in a subset of 34 patients who underwent concomitant transjugular liver biopsy.

RESULTS

Histological α-SMA proportionate area correlated with enhanced liver fibrosis (ELF) score (Spearman's ρ = 0.660, p < .001), markers of collagen formation (PRO-C3, ρ = 0.717, p < .001; PRO-C6, ρ = 0.526, p = .002) and tissue inhibitor of metalloproteinases-1 (TIMP1; ρ = 0.547, p < .001), indicating that these blood biomarkers are capable of reflecting the dynamic process of ECM turnover. CRP, IL-6 and PCT levels correlated with ELF, biomarkers of collagen synthesis/degradation and TIMP1, both in compensated and decompensated patients. Multivariate linear regression models (adjusted for HVPG) confirmed that CRP, IL-6 and PCT were independently linked to markers of liver fibrogenesis and ECM turnover.

CONCLUSION

Systemic inflammation is linked to both liver fibrogenesis and ECM turnover in ACLD and this association is not confounded by the severity of liver disease, as evaluated by HVPG. Our study confirms experimental data on the detrimental impact of SI on ECM deposition and fibrosis progression in a thoroughly characterized cohort of patients with ACLD.

Clinical evaluation of bacterial DNA using an improved droplet digital PCR for spontaneous bacterial peritonitis diagnosis

Objective

Bacterial DNA (bactDNA) detection can be used to quickly identify pathogenic bacteria and has been studied on ascitic fluid. We aimed to retrospectively analyze the diagnostic value and applicational prospect of the bactDNA load in spontaneous bacterial peritonitis (SBP).

Method

We extracted viable bactDNA from ascitic samples of 250 patients with decompensated cirrhosis collected from October 2019 to April 2021 and detected the bactDNA by droplet digital polymerase chain reaction (ddPCR). We used ascitic samples of a baseline cohort of 191 patients to establish diagnostic thresholds for SBP and analyze the patients’ diagnostic performance based on ascites polymorphonuclear (PMN) and clinical manifestation. We performed bactDNA quantification analysis on 13 patients with a PMN less than 250 cells/mm³ but with clinical symptoms. The dynamic changes of the bactDNA load from eight patients (before, during, and after SBP) were analyzed.

Results

After the removal of free DNA, the bactDNA detected by ddPCR was generally decreased (1.75 vs. 1.5 log copies/µl, P < 0.001). Compared with the traditional culture and PMN count in the SBP diagnosis, the bactDNA showed that the ddPCR sensitivity was 80.5%, specificity was 95.3%, positive predictive value was 82.5%, and negative predictive value was 94.7%, based on clinical composite criteria. In patients with a PMN less than 250 cells/mm³, the bactDNA load of 13 patients with symptoms was significantly higher than those without symptoms (2.7 vs. 1.7 log copies/µl, P < 0.001). The bactDNA in eight patients had SBP that decreased by 1.6 log copies/µl after 48 h of antibiotic treatment and by 1.0 log copies/µl after 3 days of continued treatment.

Conclusion

BactDNA detection can be used to further enhance the diagnostic efficiency of SBP. Therefore, the application of ddPCR assay not only can be used to discriminate and quantify bacteria but also can be used in the clinical assessment for antibiotics treatment.

Plasma Microbiome in COVID-19 Subjects: An Indicator of Gut Barrier Defects and Dysbiosis

The gut is a well-established route of infection and target for viral damage by SARS-CoV-2. This is supported by the clinical observation that about half of COVID-19 patients exhibit gastrointestinal (GI) complications. We aimed to investigate whether the analysis of plasma could provide insight into gut barrier dysfunction in patients with COVID-19 infection. Plasma samples of COVID-19 patients (n = 146) and healthy individuals (n = 47) were collected during hospitalization and routine visits. Plasma microbiome was analyzed using 16S rRNA sequencing and gut permeability markers including fatty acid binding protein 2 (FABP2), peptidoglycan (PGN), and lipopolysaccharide (LPS) in both patient cohorts. Plasma samples of both cohorts contained predominately Proteobacteria, Firmicutes, Bacteroides, and Actinobacteria. COVID-19 subjects exhibit significant dysbiosis (p = 0.001) of the plasma microbiome with increased abundance of Actinobacteria spp. (p = 0.0332), decreased abundance of Bacteroides spp. (p = 0.0003), and an increased Firmicutes:Bacteroidetes ratio (p = 0.0003) compared to healthy subjects. The concentration of the plasma gut permeability marker FABP2 (p = 0.0013) and the gut microbial antigens PGN (p < 0.0001) and LPS (p = 0.0049) were significantly elevated in COVID-19 patients compared to healthy subjects. These findings support the notion that the intestine may represent a source for bacteremia and contribute to worsening COVID-19 outcomes. Therapies targeting the gut and prevention of gut barrier defects may represent a strategy to improve outcomes in COVID-19 patients.

Hydrogen Sulfide Actions in the Vasculature

Hydrogen sulfide (H2 S) is a small, gaseous molecule with poor solubility in water that is generated by multiple pathways in many species including humans. It acts as a signaling molecule in many tissues with both beneficial and pathological effects. This article discusses its many actions in the vascular system and the growing evidence of its role to regulate vascular tone, angiogenesis, endothelial barrier function, redox, and inflammation. Alterations in some disease states are also discussed including potential roles in promoting tumor growth and contributions to the development of metabolic disease. © 2021 American Physiological Society. Compr Physiol 11:1-22, 2021.

Intestinal dysbiosis in nonalcoholic fatty liver disease (NAFLD): focusing on the gut-liver axis

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver disorders in humans, partly because it is closely related to metabolic disorders of the liver with increasing prevalence. NAFLD begins with hepatic lipid accumulation, which may cause inflammation and eventually lead to fibrosis in the liver. Numerous studies have demonstrated the close relationship between gut dysfunction (especially the gut microbiota and its metabolites) and the occurrence and progression of NAFLD. The bidirectional communication between the gut and liver, named the gut-liver axis, is mainly mediated by the metabolites derived from both the liver and gut through the biliary tract, portal vein, and systemic circulation. Herein, we review the effects of the gut-liver axis on the pathogenesis of NAFLD. We also comprehensively describe the potential molecular mechanisms from the perspective of the role of liver-derived metabolites and gut-related components in hepatic metabolism and inflammation and gut health, respectively. The study provides insights into the mechanisms underlying current summarizations that support the intricate interactions between a disordered gut and NAFLD and can provide novel strategies to lessen the prevalence and consequence of NAFLD.

Portal Venous Flow Is Increased by Jejunal but Not Colonic Hydrogen Sulfide in a Nitric Oxide-Dependent Fashion in Rats

Hydrogen sulfide (H2S) is a recently discerned endogenous signaling molecule that modulates the vascular system. Endogenous hydrogen sulfide has been shown to dilate both the mesenteric and portal vasculature. Gut microbiome, via sulfur reducing bacteria, is another source of H2S production within the gut lumen; this source of H2S is primarily produced and detoxified in the colon under physiologic conditions. Nitric oxide (NO), a major endogenous vasodilator in the portal circulation, participates in H2S-induced vasodilation in some vascular beds. We hypothesize that jejunal but not colonic H2S increases portal vein flow in a NO-dependent fashion. To evaluate the effects of luminal H2S, venous blood flow, portal venous pressure, and systemic venous pressure were measured in rats after administration of either vehicle or an H2S donor (NaHS) into the jejunum or the colon. We found that portal venous pressure and systemic pressure did not change and were similar between the three study groups. However, portal venous blood flow significantly increased following jejunal administration of NaHS but not in response to colonic NaHS or vehicle administration. To test the contribution of NO production to this response, another group of animals was treated with either an NO synthase inhibitor (N-Ω-nitro-L-arginine, L-NNA) or saline prior to jejunal NaHS infusion. After L-NNA pretreatment, NaHS caused a significant fall rather than increase in portal venous flow compared to saline pretreatment. These data demonstrate that H2S within the small intestine significantly increases portal venous blood flow in a NO-dependent fashion.

Plasma microbiome in COVID-19 subjects: an indicator of gut barrier defects and dysbiosis

The gut is a well-established route of infection and target for viral damage by SARS-CoV-2. This is supported by the clinical observation that about half of COVID-19 patients exhibit gastrointestinal ( GI ) symptoms. We asked whether the analysis of plasma could provide insight into gut barrier dysfunction in patients with COVID-19 infection. Plasma samples of COVID-19 patients (n=30) and healthy control (n=16) were collected during hospitalization. Plasma microbiome was analyzed using 16S rRNA sequencing, metatranscriptomic analysis, and gut permeability markers including FABP-2, PGN and LPS in both patient cohorts. Almost 65% (9 out 14) COVID-19 patients showed abnormal presence of gut microbes in their bloodstream. Plasma samples contained predominately Proteobacteria, Firmicutes, and Actinobacteria . The abundance of gram-negative bacteria ( Acinetobacter, Nitrospirillum, Cupriavidus, Pseudomonas, Aquabacterium, Burkholderia, Caballeronia, Parabhurkholderia, Bravibacterium, and Sphingomonas ) was higher than the gram-positive bacteria ( Staphylococcus and Lactobacillus ) in COVID-19 subjects. The levels of plasma gut permeability markers FABP2 (1282±199.6 vs 838.1±91.33; p=0.0757), PGN (34.64±3.178 vs 17.53±2.12; p<0.0001), and LPS (405.5±48.37 vs 249.6±17.06; p=0.0049) were higher in COVID-19 patients compared to healthy subjects. These findings support that the intestine may represent a source for bacteremia and may contribute to worsening COVID-19 outcomes. Therapies targeting the gut and prevention of gut barrier defects may represent a strategy to improve outcomes in COVID-19 patients.

Liver Sinusoidal Endothelial Cells Contribute to Hepatic Antigen-Presenting Cell Function and Th17 Expansion in Cirrhosis

Hepatic immune function is compromised during cirrhosis. This study investigated the immune features of liver sinusoidal endothelial cells (LSECs) in two experimental models of cirrhosis. Dendritic cells, hepatic macrophages, and LSECs were isolated from carbon tetrachloride and bile duct-ligated rats. Gene expression of innate receptors, bacterial internalization, co-stimulatory molecules induction, and CD4+ T cell activation and differentiation were evaluated. Induced bacterial peritonitis and norfloxacin protocols on cirrhotic rats were also carried out. LSECs demonstrated an active immunosurveillance profile, as shown by transcriptional modulation of different scavenger and cell-adhesion genes, and their contribution to bacterial internalization. LSECs significantly increased their expression of CD40 and CD80 and stimulated CD4+ T cell activation marker CD71 in both models. The pro-inflammatory Th17 subset was expanded in CCl₄-derived LSECs co-cultures. In the bile duct ligation (BDL) model, CD4+ T cell differentiation only occurred under induced bacterial peritonitis conditions. Differentiated pro-inflammatory Th cells by LSECs in both experimental models were significantly reduced with norfloxacin treatment, whereas Foxp3 tolerogenic Th CD4+ cells were expanded. Conclusion: LSECs’ participation in the innate-adaptive immune progression, their ability to stimulate pro-inflammatory CD4+ T cells expansion during liver damage, and their target role in norfloxacin-induced immunomodulation granted a specific competence to this cell population in cirrhosis.

Gastrointestinal Failure in Critically Ill Patients With Cirrhosis

Gastrointestinal failure (GIF) is frequent in patients managed in the intensive care units and manifests as gut paralysis or ileus. GIF is often associated with sepsis or multiorgan failure. In critically ill patients, the precipitating causes of GIF include inflammation, sepsis, electrolyte abnormalities, and acidosis. It is possible that GIF is associated with an increase in bacterial translocation, especially in those with cirrhosis and portal hypertension, and this may play a significant pathogenic or prognostic role in acute-on-chronic liver failure (ACLF). The critical care literature suggests that GIF is associated with a higher mortality risk. In this review, we summarize the evidence for a potential association between GIF and ACLF and propose treatment options for the management of GIF. Moreover, we suggest GIF to be considered as another organ failure when the severity of ACLF is assessed.

Dysbiosis of the gut microbiome is associated with CKD5 and correlated with clinical indices of the disease: a case-controlled study

BACKGROUND

Chronic kidney disease (CKD) is a universal chronic disease in China. The balance of the gut microbiome is highly crucial for a healthy human body, especially for the immune system. However, the relationship between the gut microbiome and CKD has not yet been clarified.

METHODS

A total of 122 patients were recruited for this study. Among them, 24 patients were diagnosed with CKD5 but did not receive hemodialysis therapy, 29 patients were diagnosed with CKD5 and received hemodialysis therapy and 69 were matched healthy controls. The gut microbiome composition was analyzed by a 16S rRNA (16S ribosomal RNA) gene-based sequencing protocol. High-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS) technology was used to evaluate the levels of microbiome-related protein-binding uremic toxins level, indoxyl sulfate (IS) and p-cresyl sulfate (PCS), in the patients.

RESULTS

We compared the gut microbiome results of 122 subjects and established a correlation between the gut microbiome and IS and PCS levels. The results indicated that alpha and beta diversity were different in patients with CKD5 than in the healthy controls (p < 0.01). In comparison to healthy controls, CKD5 patients exhibited a significantly higher relative abundance of Neisseria (p < 0.001), Lachnoclostridium (p < 0.001) and Bifidobacterium (p < 0.001). Faecalibacterium (p < 0.001) displayed a notably lower relative abundance for CKD5 patients both with and without hemodialysis than for controls. It was also found that the concentrations of IS and PCS were correlated with the gut microbiome.

CONCLUSIONS

Our results indicate that CKD5 patients both with and without hemodialysis had dysbiosis of the gut microbiome and that this dysbiosis was associated with an accumulation of IS and PCS. These results may support further clinical diagnosis to a great extent and help in developing potential probiotics to facilitate the treatment of CKD5.

Treatment with non-selective beta-blockers affects the systemic inflammatory response to bacterial DNA in patients with cirrhosis

BACKGROUND & AIMS

The use of non-selective beta-blockers has been associated with lower rates of infection and reduced infection-associated morbidity in patients with cirrhosis. However, it is unknown if these drugs modify the systemic inflammatory response to circulating bacterial DNA.

METHODS

Sixty-three patients with cirrhosis were included during an episode of decompensation by ascites. Thirty of those patients were on beta-blockers. Blood samples were obtained after each patient had been in the supine position for at least 30 minutes in a quiet atmosphere. Bacterial DNA, serum cytokines, nitric oxide, and LPS were determined. Phagocytic and oxidative burst activities were determined in polymorphonuclear cells from the patients.

RESULTS

The detection rate of bacterial DNA in the blood was the same (33%) for patients not treated and treated with non-selective beta-blockers. Patients naive to non-selective beta-blockers showed significantly higher serum levels of IL6, IFN-gamma and IL10 in response to the presence of bacterial DNA. Patients treated with non-selective beta-blockers showed higher basal inflammatory activity that did not change with the presence of bacterial DNA. Monocytes and granulocytes from patients treated with non-selective beta-blockers showed a significantly increased phagocytic capacity in the presence of bacterial DNA.

CONCLUSIONS

In patients with cirrhosis, chronic treatment with beta-blockers is associated with a higher unstimulated production of serum cytokines and an increased phagocytic activity in the presence of bacterial DNA.

Mesenchymal stem cell transplantation improves chronic colitis-associated complications through inhibiting the activity of toll-like receptor-4 in mice

Background

A variety of extra-intestinal manifestations (EIMs), including hepatobiliary complications, are associated with inflammatory bowel disease (IBD). Mesenchymal stem cells (MSCs) have been shown to play a potential role in the therapy of IBD. This study was designed to investigate the effect and mechanism of MSCs on chronic colitis-associated hepatobiliary complications using mouse chronic colitis models induced by dextran sulfate sodium (DSS).

Methods

DSS-induced mouse chronic colitis models were established and treated with MSCs. Severity of colitis was evaluated by disease activity index (DAI), body weight (BW), colon length and histopathology. Serum lipopolysaccharide (LPS) levels were detected by limulus amebocyte lysate test (LAL-test). Histology and liver function of the mice were checked correspondingly. Serum LPS levels and bacterial translocation of mesenteric lymph nodes (MLN) were detected. Pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-1β (IL-1β), interleukin-17A (IL-17A), Toll receptor 4 (TLR4), TNF receptor-associated factor 6 (TRAF6) and nuclear factor kappa B (NF-κB) were detected by immunohistochemical staining, western blot analysis and real-time PCR, respectively.

Results

The DSS-induced chronic colitis model was characterized by reduced BW, high DAI, worsened histologic inflammation, and high levels of LPS and E. coli. Liver histopathological lesions, impaired liver function, enhanced proteins and mRNA levels of TNF-α, IFN-γ, IL-1β, IL-17A, TLR4, TRAF6 and NF-κB were observed after DSS administration. MSCs transplantation markedly ameliorated the pathology of colon and liver by reduction of LPS levels and proteins and mRNA expressions of TNF-α, IFN-γ, IL-1β, IL-17A, TLR4, TRAF6 and NF-κB.

Conclusions

MSCs can improve chronic colitis-associated hepatobiliary complications, probably by inhibition of enterogenous endotoxemia and hepatic inflammation through LPS/TLR4 pathway. MSCs may represent a novel therapeutic approach for chronic colitis-associated hepatobiliary complications.

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.

Norfloxacin is more effective than Rifaximin in avoiding bacterial translocation in an animal model of cirrhosis

BACKGROUND & AIMS

Norfloxacin administration is useful in preventing bacterial infections in cirrhosis but associated to the generation of resistant species. Rifaximin is known to reach high concentrations in the intestinal lumen without generating relevant resistance in the intestinal flora. Our aim was to compare the effect of Norfloxacin and Rifaximin on intestinal flora composition, bacterial translocation and survival in cirrhotic rats.

METHODS

Cirrhosis was induced in rats by oral administration of CCl₄ . Animals were divided into three groups: only CCl₄ (group I, n = 10); CCl₄ + Norfloxacin (group II, n = 17) and CCl₄ + Rifaximin (group III, n = 14). Gut bacterial composition, bacterial translocation and cytokine levels were measured.

RESULTS

Forty-one rats were finally included. The incidence of viable and non-viable bacterial translocation was significantly reduced in animals receiving Norfloxacin; Rifaximin also decreased the incidence of viable and non-viable bacterial translocation, but did not reach statistical significance. Serum TNF-α levels were significantly lower in antibiotic groups. Norfloxacin modified intestinal microbiota, depleting significantly more pathobionts than Rifaximin.

CONCLUSION

Norfloxacin is more effective than Rifaximin in preventing bacterial translocation in rats with cirrhosis probably because of its capacity to reduce pathobionts from intestinal microbiota.

Alteration of the gut microbiota in Chinese population with chronic kidney disease

We evaluated differences in the compositions of faecal microbiota between 52 end stage renal disease (ESRD) patients and 60 healthy controls in southern China using quantitative real-time polymerase chain reaction (qPCR) and high-throughput sequencing (16S ribosomal RNA V4-6 region) methods. The absolute quantification of total bacteria was significantly reduced in ESRD patients (p < 0.01). In three enterotypes, Prevotella was enriched in the healthy group whereas Bacteroides were prevalent in the ESRD group (LDA score > 4.5). 11 bacterial taxa were significantly overrepresented in samples from ESRD and 22 bacterial taxa were overrepresented in samples from healthy controls. The butyrate producing bacteria, Roseburia, Faecalibacterium, Clostridium, Coprococcus and Prevotella were reduced in the ESRD group (LDA values > 2.0). Canonical correspondence analysis (CCA) indicated that Cystatin C (CysC), creatinine and eGFR appeared to be the most important environmental parameters to influence the overall microbial communities. In qPCR analysis, The butyrate producing species Roseburia spp., Faecalibacterium prausnitzii, Prevotella and Universal bacteria, were negatively related to CRP and CysC. Total bacteria in faeces were reduced in patients with ESRD compared to that in healthy individuals. The enterotypes change from Prevotella to Bacteroides in ESRD patients. The gut microbiota was associated with the inflammatory state and renal function of chronic kidney disease.

Bacterial translocation in critical illness

Bacterial translocation involves the passage of intestinal bacteria to extraintestinal sites and has been shown to increase morbidity and mortality in critical illness. This review outlines the pathophysiology of bacterial translocation, host defence mechanisms, and reviews the evidence for the clinical management of critically ill patients in order to minimise the negative outcomes associated with bacterial translocation.

Selective intestinal decontamination with norfloxacin enhances a regulatory T cell-mediated inflammatory control mechanism in cirrhosis

BACKGROUND & AIMS

Norfloxacin exerts immunomodulatory effects in cirrhosis beyond its bactericidal activity. We aimed at identifying the role of regulatory T (Treg) cells in the norfloxacin mechanism that compensates the inflammatory environment in cirrhosis.

PATIENTS & METHODS

Consecutively admitted patients with cirrhosis and ascitic fluid (AF) with: spontaneous bacterial peritonitis (SBP), non-infected AF, and norfloxacin as secondary SBP prophylaxis (SID group). Tregs were defined by flow-cytometry as CD4⁺ CD25⁺ FoxP3⁺ cells. Dendritic cells (DCs) were purified for co-stimulatory signalling evaluation and norfloxacin and IL-10 levels were measured in serum. Wildtype and recombination activating gene 1 (Rag1)-deficient mice with CCl₄ -induced cirrhosis were used for adoptive-transfer experiments using naïve CD4⁺ T cells and Tregs.

RESULTS

Eighty-four patients were included. Treg percentage was significantly increased in SID patients compared with SBP or non-infected AF patients. A positive correlation was observed between Tregs and serum norfloxacin and IL-10 levels. DCs from SID patients showed a significantly decreased expression of CD80 and CD86 compared with SBP and non-infected AF patients and correlated with norfloxacin levels. Modulation of co-stimulatory signalling by norfloxacin was not detected in Rag1-deficient mice and Rag1-deficient mice reconstituted with naïve T-cells. However, reconstitution with naïve T-cells and Tregs was associated with significantly downregulated CD80 and CD86 expression in the presence of norfloxacin. Norfloxacin immunomodulatory effect on IL-2 and IFN-gamma reduction and on the increase of IL-10 was significantly achieved only when the Tregs were restored in Rag1-deficient mice.

CONCLUSIONS

These results provide a plausible mechanism for the immunomodulatory effects of norfloxacin in cirrhosis beyond its bactericidal effect.

Use of molecular typing to investigate bacterial translocation from the intestinal tract of chlorpyrifos-exposed rats

BACKGROUND

Human are confronted on a daily basis with contaminant pesticide residues in food, water and other components of the environment. Although the digestive system is the first organ to come into contact with food contaminants, very few data are available on the impact of low-dose pesticide exposure during the in utero and postnatal periods on intestinal bacterial translocation (BT). Previous studies have revealed that chlorpyrifos (CPF) exposure is associated with intestinal dysbiosis and the contamination of sterile organs. Here, molecular typing was used to investigate intestinal bacterial translocation in rats exposed to chlorpyrifos in utero and during lactation. The translocated bacteria were profiled, and CPF tolerance and antibiotic resistance traits were determined.

METHODS

A total of 72 intestinal segments and extra-intestinal organs were obtained from 14 CPF-exposed rats. The samples were cultured to isolate bacterial strains that had tolerated treatment with 1 or 5 mg CPF/kg bodyweight/day in vivo. Strains were identified using matrix-assisted laser desorption/ionization (MALDI) Biotyper. The disk diffusion method was used to determine the antibiotic susceptibility. The isolates were genotyped with PCR assays for the enterobacterial repetitive intergenic consensus sequence and random amplification polymorphic DNA.

RESULTS

Bacterial translocation was confirmed for 7 of the 31 strains (22.6 %) isolated from extra-intestinal sites. Overall, the most prevalent bacteria were Staphylococcus aureus (55.5 % of the 72 intestinal and extra-intestinal isolates), Enterococcus faecalis (27.7 %) and Bacillus cereus (9.8 %). 5 % of the S. aureus isolates displayed methicillin resistance. Seventy two strains were identified phenotypically, and seven translocated strains (mainly S. aureus) were identified by genotyping. Genotypically confirmed translocation was mainly observed found in pesticide-exposed groups (6 out of 7).

CONCLUSION

BT from the intestinal tract colonized normally sterile extra-intestinal organs in CPF-exposed rats. Our findings validate the use of molecular typing for the assessment of intestinal BT in CPF-exposed rats during critical periods of development.

Grade of soluble inflammatory response is mainly affected by circulating bacterial DNA concentrations in cirrhosis

BACKGROUND & AIMS

Patients with decompensated cirrhosis show a marked innate immune response that shows a wide variability. The reasons for this fact have not been previously evaluated. This investigation was undertaken to study factors influencing the immune response intensity in both serum and ascitic fluid in patients with cirrhosis and ascites with presence of bactDNA.

METHODS

77 patients with cirrhosis and presence of bactDNA fragments in blood and ascitic fluid were included. Identification of bactDNA was evaluated by 16SrRNA gene PCR followed by nucleotide sequencing and by species-specific PCR. Concentration of amplified bacterial-DNA, bacteria identification, LPS, TNF-alpha, IFN-gamma, Interleukin 12 and nitric oxide in serum and ascitic fluid were evaluated as factors related to intensity of the immune response.

RESULTS

Serum and AF levels of bactDNA, TNF-α, IFN-γ and nitric oxide concentration were higher in patients with presence of bactDNA from gram negative bacteria. Serum TNF-α levels showed a significant correlation with concentrations of bactDNA (r = 0.88; P = 0.001) and LPS (r = 0.28; P = 0.016). Serum nitric oxide levels were also significantly correlated with concentrations of bactDNA (r = 0.761; P = 0.001) but not with LPS levels. Levels of INF-γ and IL-12 were not significantly correlated with either bactDNA nor LPS levels. Plasmatic concentration of bactDNA was the most accurately correlated factor with the inflammatory response (ancova model included only levels of bactDNA (r(2) = 0.87, P = 0.047 for TNF-α; r(2) = 0.45, P = 0.03 for NOx).

CONCLUSIONS

Bacterial-DNA concentration is the most influencing variable associated with serum TNF-α and nitric oxide response.

Effect of artesunate supplementation on bacterial translocation and dysbiosis of gut microbiota in rats with liver cirrhosis

AIM: To evaluate the effect of artesunate (AS) supplementation on bacterial translocation (BT) and gut microbiota in a rat model of liver cirrhosis.

METHODS: Fifty-four male Sprague-Dawley rats were randomly divided into a normal control group (N), a liver cirrhosis group (M) and a liver cirrhosis group intervened with AS (MA). Each group was sampled at 4, 6 and 8 wk. Liver cirrhosis was induced by injection of carbon tetrachloride (CCl₄), intragastric administration of 10% ethanol, and feeding a high fat diet. Rats in the MA group were intragastrically administered with AS (25 mg/kg body weight, once daily). Injuries of the liver and intestinal mucosa were assessed by hematoxylin-eosin or Masson’s trichrome staining. Liver index was calculated as a ratio of the organ weight (g) to body weight (g). The gut microbiota was examined by automated ribosomal intergenic-spacer analysis of fecal DNA. BT was assessed by standard microbiological techniques in the blood, mesenteric lymph nodes (MLNs), liver, spleen, and kidney.

RESULTS: Compared to group N, the body weight was reduced significantly in groups M and MA due to the development of liver cirrhosis over the period of 8 wk. The body weight was higher in group MA than in group M. The liver indices were significantly elevated at 4, 6 and 8 wk in groups M and MA compared to group N. AS supplementation partially decreased the liver indices in group MA. Marked histopathologic changes in the liver and small intestinal mucosa in group M were observed, which were alleviated in group MA. Levels of pro-inflammatory interleukin-6 and tumor necrosis factor-α were significantly elevated at 8 wk in ileal homogenates in group M compared to group N, which were decreased after AS supplementation in group MA. The dysbiosis of gut microbiota indicated by the mean diversity (Shannon index) and mean similarity (Sorenson index) was severe as the liver cirrhosis developed, and AS supplementation had an apparent intervention effect on the dysbiosis of gut microbiota at 4 wk. The occurrence of BT was increased in the liver of group M compared to that of group N. AS supplementation reduced BT in group MA at 8 wk. BT also occurred in the MLNs, spleen, and kidney, which was reduced by AS supplementation. BT was not detected in the blood in any group.

CONCLUSION: Dysbiosis of gut microbiota, injury of intestinal mucosal barrier and BT occurred as liver cirrhosis progressed, which might enhance inflammation and aggravate liver injury. AS may have other non-antimalarial effects that modulate gut microbiota, inhibit BT and alleviate inflammation, resulting in a reduction in CCl₄, alcohol and high fat-caused damages to the liver and intestine.

Loss of NHE8 expression impairs intestinal mucosal integrity

The newest member of the Na(+)/H(+) exchanger (NHE) family, NHE8, is abundantly expressed at the apical membrane of the intestinal epithelia. We previously reported that mucin 2 expression was significantly decreased in the colon in NHE8(-/-) mice, suggesting that NHE8 is involved in intestinal mucosal protection. In this study, we further evaluated the role of NHE8 in intestinal epithelial protection after dextran sodium sulfate (DSS) challenge. Compared with wild-type mice, NHE8(-/-) mice have increased bacterial adhesion and inflammation, especially in the distal colon. NHE8(-/-) mice are also susceptible to DSS treatment. Real-time PCR detected a remarkable increase in the expression of IL-1β, IL-6, TNF-α, and IL-4 in DSS-treated NHE8(-/-) mice compared with DSS-treated wild-type littermates. Immunohistochemistry showed a disorganized epithelial layer in the colon of NHE8(-/-) mice. Periodic acid-Schiff staining showed a reduction in the number of mature goblet cells and the area of the goblet cell theca in NHE8(-/-) mice. Phyloxine/tartrazine staining revealed a decrease in functional Paneth cell population in the NHE8(-/-) small intestinal crypt. The expression of enteric defensins was also decreased in NHE8(-/-) mice. The reduced mucin production in goblet cells and antimicrobial peptides production in Paneth cells lead to disruption of the intestinal mucosa protection. Therefore, NHE8 may be involved in the establishment of intestinal mucosal integrity by regulating the functions of goblet and Paneth cells.

Gut Microbiota and Host Reaction in Liver Diseases

Although alcohol feeding produces evident intestinal microbial changes in animals, only some alcoholics show evident intestinal dysbiosis, a decrease in Bacteroidetes and an increase in Proteobacteria. Gut dysbiosis is related to intestinal hyperpermeability and endotoxemia in alcoholic patients. Alcoholics further exhibit reduced numbers of the beneficial Lactobacillus and Bifidobacterium. Large amounts of endotoxins translocated from the gut strongly activate Toll-like receptor 4 in the liver and play an important role in the progression of alcoholic liver disease (ALD), especially in severe alcoholic liver injury. Gut microbiota and bacterial endotoxins are further involved in some of the mechanisms of nonalcoholic fatty liver disease (NAFLD) and its progression to nonalcoholic steatohepatitis (NASH). There is experimental evidence that a high-fat diet causes characteristic dysbiosis of NAFLD, with a decrease in Bacteroidetes and increases in Firmicutes and Proteobacteria, and gut dysbiosis itself can induce hepatic steatosis and metabolic syndrome. Clinical data support the above dysbiosis, but the details are variable. Intestinal dysbiosis and endotoxemia greatly affect the cirrhotics in relation to major complications and prognosis. Metagenomic approaches to dysbiosis may be promising for the analysis of deranged host metabolism in NASH and cirrhosis. Management of dysbiosis may become a cornerstone for the future treatment of liver diseases.

Markers of bacterial translocation in end-stage liver disease

Bacterial translocation (BT) refers to the passage of viable bacteria or bacterial products from the intestinal lumen, through the intestinal epithelium, into the systemic circulation and extraintestinal locations. The three principal mechanisms that are thought to be involved in BT include bacterial overgrowth, disruption of the gut mucosal barrier and an impaired host defence. BT is commonly observed in liver cirrhosis and has been shown to play an important role in the pathogenesis of the complications of end stage liver disease, including infections as well as hepatic encephalopathy and hepatorenal syndrome. Due to the importance of BT in the natural history of cirrhosis, there is intense interest for the discovery of biomarkers of BT. To date, several such candidates have been proposed, which include bacterial DNA, soluble CD14, lipopolysaccharides endotoxin, lipopolysaccharide-binding protein, calprotectin and procalcitonin. Studies on the association of these markers with BT have demonstrated not only promising data but, oftentimes, contradictory results. As a consequence, currently, there is no optimal marker that may be used in clinical practice as a surrogate for the presence of BT.

Gut-liver axis in liver cirrhosis: How to manage leaky gut and endotoxemia

A “leaky gut” may be the cutting edge for the passage of toxins, antigens or bacteria into the body, and may play a pathogenic role in advanced liver cirrhosis and its complications. Plasma endotoxin levels have been admitted as a surrogate marker of bacterial translocation and close relations of endotoxemia to hyperdynamic circulation, portal hypertension, renal, cardiac, pulmonary and coagulation disturbances have been reported. Bacterial overgrowth, increased intestinal permeability, failure to inactivate endotoxin, activated innate immunity are all likely to play a role in the pathological states of bacterial translocation. Therapeutic approach by management of the gut-liver axis by antibiotics, probiotics, synbiotics, prebiotics and their combinations may improve the clinical course of cirrhotic patients. Special concern should be paid on anti-endotoxin treatment. Adequate management of the gut-liver axis may be effective for prevention of liver cirrhosis itself by inhibiting the progression of fibrosis.

Spontaneous bacterial peritonitis: The clinical challenge of a leaky gut and a cirrhotic liver

Spontaneous bacterial peritonitis (SBP) is a frequent, life-threatening bacterial infection in patients with liver cirrhosis and ascites. Portal hypertension leads to increased bacterial translocation from the intestine. Failure to eliminate invading pathogens due to immune defects associated with advanced liver disease on the background of genetic predisposition may result in SBP. The efficacy of antibiotic treatment and prophylaxis has declined due to the spread of multi-resistant bacteria. Patients with nosocomial SBP and with prior antibiotic treatment are at a particularly high risk for infection with resistant bacteria. Therefore, it is important to adapt empirical treatment to these risk factors and to the local resistance profile. Rifaximin, an oral, non-absorbable antibiotic, has been proposed to prevent SBP, but may be useful only in a subset of patients. Since novel antibiotic classes are lacking, we have to develop prophylactic strategies which do not induce bacterial resistance. Farnesoid X receptor agonists may be a candidate, but so far, clinical studies are not available. New diagnostic tests which can be carried out quickly at the patient’s site and provide additional prognostic information would be helpful. Furthermore, we need tools to predict antibiotic resistance in order to tailor first-line antibiotic treatment of spontaneous bacterial peritonitis to the individual patient and to reduce mortality.

The impact of bacterial DNA translocation on early postoperative outcomes in Crohn's patients undergoing abdominal surgery

BACKGROUND AND AIMS

Bacterial DNA (bactDNA) translocation occurs frequently in patients with Crohn's disease and can be present in patients with a negative blood microbiological culture. We aimed to determine the effects of bactDNA translocation on postoperative outcomes in Crohn's disease patients undergoing abdominal surgery.

METHODS

Patients with Crohn's disease who underwent abdominal surgery between January 2012 and March 2014 were identified. General and postoperative outcome-related information was retrieved from a database, and the data were compared between patients with and without bactDNA translocation. Multivariate analysis was used to determine the independent effect of bactDNA translocation on postoperative morbidity.

RESULTS

One hundred and seven patients who underwent abdominal surgery were included in our study. The presence of bactDNA in blood samples was identified in 29 patients (27.1%). There was a total of 55 complications in 28 patients (26.2%). Patients with bactDNA in their blood had a mean postoperative hospital stay of 12.7±4.2 days and patients without DNA translocation had a mean postoperative hospital stay of 10.1±4.8 days (p = 0.009). The readmission rate was increased in patients with bactDNA translocation (p = 0.032). A low preoperative level of serum albumin (p = 0.024), preoperative immunosuppressive agent use (p = 0.046), and the presence of bactDNA in blood (p = 0.005) were independently associated with increased postoperative adverse outcomes.

CONCLUSIONS

Preoperative bactDNA translocation into the blood increases the incidence of postoperative adverse outcomes in patients with Crohn's disease who undergo abdominal surgery.

Is intestinal inflammation linking dysbiosis to gut barrier dysfunction during liver disease?

Changes in the intestinal microbiota composition contribute to the pathogenesis of many disorders including gastrointestinal and liver diseases. Recent studies have broadened our understanding of the "gut-liver" axis. Dietary changes, other environmental and genetic factors can lead to alterations in the microbiota. Dysbiosis can further disrupt the integrity of the intestinal barrier leading to pathological bacterial translocation and the initiation of an inflammatory response in the liver. In this article, the authors dissect the different steps involved in disease pathogenesis to further refine approaches for the medical management of liver diseases. The authors will specifically discuss the role of dysbiosis in inducing intestinal inflammation and increasing intestinal permeability.

Role of interleukin 10 in norfloxacin prevention of luminal free endotoxin translocation in mice with cirrhosis

BACKGROUND & AIMS

Bacterial endotoxin is present in patients with advanced cirrhosis and can induce an immunogenic response without an overt infection. Norfloxacin is a gram-negative bactericidal drug able to maintain low endotoxin levels and stimulate IL-10 production. We aimed at investigating the role of IL-10 in decreasing endotoxin absorption in cirrhotic mice treated with norfloxacin.

METHODS

Cirrhosis was induced by carbon tetrachloride or bile duct ligation in wild type and IL10-deficient mice with or without norfloxacin prior to an intragastrical administration of E. coli, K. pneumonia or E. faecalis. Spontaneous and induced bacterial translocation, free endotoxin and cytokine levels were evaluated in mesenteric lymph nodes. Intestinal permeability was followed by fluorimetry and barrier integrity markers were measured in disrupted intestinal samples. The inflammatory-modulating mechanism was characterized in purified intestinal mononuclear cells.

RESULTS

Norfloxacin reduced spontaneous and induced MLN positive-cultures in wild type and IL-10-deficient animals. However, reduction of free endotoxin levels was associated with norfloxacin in wild type but not in IL-10-deficient mice. Wild type but not IL-10-deficient mice treated with norfloxacin significantly normalized intestinal permeability and improved gut barrier integrity markers. The toll-like receptor 4-mediated pro-inflammatory milieu was modulated by norfloxacin in a concentration-dependent manner in cultured intestinal mononuclear cells of wild type mice but not of IL-10-deficient mice. The restoration of IL-10 levels in IL-10-deficient animals reactivated the norfloxacin effect on inflammatory-modulation, gut barrier permeability, and luminal endotoxin absorption.

CONCLUSION

Norfloxacin not only reduces gram-negative intestinal flora but also participates in an IL-10-driven modulation of gut barrier permeability, thus reducing luminal free endotoxin absorption in experimental cirrhosis.

Intestinal translocation of clinical isolates of vancomycin-resistant Enterococcus faecalis and ESBL-producing Escherichia coli in a rat model of bacterial colonization and liver ischemia/reperfusion injury

The objectives of this study were to develop a rat model of gastrointestinal colonization with vancomycin-resistant Enterococcus faecalis (VRE) and extended-spectrum beta-lactamase (ESBL)-producing E. coli and to evaluate intestinal translocation to blood and tissues after total and partial hepatic ischemia. Methods - We developed a model of rat colonization with VRE and ESBL-E coli. Then we studied four groups of colonized rats: Group I (with hepatic pedicle occlusion causing complete liver ischemia and intestinal stasis); Group II (with partial liver ischemia without intestinal stasis); Group III (surgical manipulation without hepatic ischemia or intestinal stasis); Group IV (anesthetized without surgical manipulation). After sacrifice, portal and systemic blood, large intestine, small intestine, spleen, liver, lungs, and cervical and mesenteric lymph nodes were cultured. Endotoxin concentrations in portal and systemic blood were determined. Results - The best inocula were: VRE: 2.4×10(10) cfu and ESBL-E. coli: 1.12×10(10) cfu. The best results occurred 24 hours after inoculation and antibiotic doses of 750 µg/mL of water for vancomycin and 2.1 mg/mL for ceftriaxone. There was a significantly higher proportion of positive cultures for ESBL-E. coli in the lungs in Groups I, II and III when compared with Group IV (67%; 60%; 75% and 13%, respectively; p:0.04). VRE growth was more frequent in mesenteric lymph nodes for Groups I (67%) and III (38%) than for Groups II (13%) and IV (none) (p:0.002). LPS was significantly higher in systemic blood of Group I (9.761 ± 13.804 EU/mL-p:0.01). No differences for endotoxin occurred in portal blood. Conclusion -We developed a model of rats colonized with resistant bacteria useful to study intestinal translocation. Translocation occurred in surgical procedures with and without hepatic ischemia-reperfusion and probably occurred via the bloodstream. Translocation was probably lymphatic in the ischemia-reperfusion groups. Systemic blood endotoxin levels were higher in the group with complete hepatic ischemia.

Protective effect of Bifidobacterium pseudocatenulatum CECT7765 against induced bacterial antigen translocation in experimental cirrhosis

BACKGROUND & AIMS

Intervention in the gut ecosystem is considered as a potential strategy to treat liver diseases and their complications. We have evaluated the effects of Bifidobacterium pseudocatenulatum CECT7765 on bacterial translocation and the liver status in experimental cirrhosis.

ANIMALS & METHODS

Liver damage was induced in Balb/c mice by weight-controlled oral administration of carbon tetrachloride. Laparotomies were performed at week 12. One week prior to laparotomy, animals received B. pseudocatenulatum CECT7765 (10(9) cfu/daily) or placebo intragastrically. All animals received Escherichia coli (10(7) cfu/single dose) intragastrically 24 hours before laparotomy. A group of naïve non-treated animals was included as control. Liver tissue specimens, mesenteric lymph nodes, intestinal content and blood were collected. Liver histology, profibrogenic genes expression, bacterial DNA translocation, serum endotoxaemia and liver cytokine levels were measured.

RESULTS

Bifidobacterium pseudocatenulatum CECT7765 showed no significant effect on structural liver damage, as determined by histological evaluation, alpha-smooth muscle actin distribution, profibrogenic gene expression levels, total hydroxyproline levels and malon dialdehyde production compared with mice receiving placebo. Interestingly, bacterial DNA translocation and serum endotoxin levels were significantly decreased in mice receiving the Bifidobacterium strain compared with placebo. Gut barrier integrity markers were up-regulated in mice receiving B. pseudocatenulatum CECT7765 and quantitatively correlated with intestinal gene copy numbers of the bifidobacterial strain. Gene expression levels of several anti-inflammatory mediators were also increased in mice receiving B. pseudocatenulatum CECT7765 compared with placebo.

CONCLUSION

Oral administration of B. pseudocatenulatum CECT7765 is associated with improved gut barrier integrity and shows a beneficial effect against induced bacterial antigen translocation in the CCl4 -model of cirrhosis.

Bacterial DNA translocation holds increased insulin resistance and systemic inflammatory levels in morbid obese patients

BACKGROUND

Morbidly obese patients show several common comorbidities associated with immunological alterations such as a sustained low-level proinflammatory profile. Bacterial product translocation is frequent in inflammation-related diseases and may aggravate patients' clinical outcome.

DESIGN

Consecutively admitted morbidly obese patients who presented indications for bariatric surgery were studied. Before surgery, patients were subjected to a modified fasting diet. Patients underwent surgery by sleeve gastrectomy or laparoscopic Roux-en-Y gastric bypass. Clinical and analytical parameters were recorded. Blood samples were collected at baseline, at the end of a 3-month modified fasting period, and 3, 6, and 12 months after surgery. Serum cytokine and endotoxin levels were evaluated by flow cytometry and ELISA, respectively. Bacterial DNA was identified in blood by broad-range PCR of prokaryote 16SrRNA gene and partial sequencing analysis.

RESULTS

Fifty-eight patients were included in the study. All patients showed a significantly reduced weight and body mass index at each time-point. Postoperative mortality was null. Bacterial DNA translocation rate was 32.8% (19 of 58) at baseline; 13.8% (8 of 58) after the modified fasting period; and 13.8% (8 of 58), 1.8% (1 of 58), and 5.2% (3 of 58) at 3, 6, and 12 months after surgery. Proinflammatory cytokines, serum endotoxin levels, and insulin resistance remained increased in patients with bacterial DNA despite weight loss and were individually affected by the appearance/clearance of bacterial DNA in blood. Multivariate analyses revealed bacterial DNA as an independent significant factor, explaining the systemic cytokine response and the insulin resistance levels in the studied population.

CONCLUSION

Bacterial DNA translocation holds increased insulin resistance and systemic inflammatory levels in morbidly obese patients despite significant weight loss.

Microbiome composition by pyrosequencing in mesenteric lymph nodes of rats with CCl4-induced cirrhosis

BACKGROUND

The cross talk between the gut microbiota and the immune system, which is essential to maintain homeostasis, takes place at the intestinal lymphoid tissue such as the mesenteric lymph nodes (MLNs). Here, we investigated the presence of bacterial DNA in MLNs of control and cirrhotic rats and its relationship with inflammatory responses.

METHODS

The MLN microbiome of cirrhotic rats with ascites, which was induced by carbon tetrachloride (CCl4), was compared to that of control rats using quantitative real-time PCR and pyrosequencing of the 16S rRNA gene. Cytokines in blood samples were assessed by ELISA.

RESULTS

Unexpectedly, sequence analysis revealed a high microbial diversity in the MLNs of both control and cirrhotic rats with Proteobacteria as one of the most dominant phylum. CCl4-induced liver injury was not associated with a change in bacterial load, but it was linked to a decrease in microbial diversity (p < 0.05) and alterations in the microbial community in MLNs. A high proportion of Bifidobacterium animalis was also positively correlated with elevated interleukin-10 expression (p = 0.002, false discovery rate = 0.03, r = 0.94).

CONCLUSIONS

For the first time, the high microbial diversity observed in MLNs of both controls and CCl4-induced cirrhotic rats provides evidence that bacterial translocation is more than a mere dichotomic phenomenon.

Role of proton pump inhibitors in the occurrence and the prognosis of spontaneous bacterial peritonitis in cirrhotic patients with ascites

BACKGROUND

Proton pump inhibitors (PPIs) facilitate intestinal bacterial translocation. No robust data exist demonstrating that PPIs increase the risk of spontaneous bacterial peritonitis (SBP) and that PPIs worsen the prognosis of SBP patients. PPI use might be unsuitable for cirrhotic patients.

AIMS

To analyse: (i) the role of PPIs in the occurrence of SBP in cirrhotic patients; (ii) their impact on the prognosis of SBP patients; and (iii) the suitability of their use.

METHODS

In this retrospective case-control study, PPI use was first assessed in cirrhotic patients consecutively admitted with SBP (group I) and in a control group that included the same number of uninfected cirrhotic patients with ascites (group II). Afterwards, the impact of PPIs on SBP was assessed in group I by comparing survival of patients with and without PPIs.

RESULTS

A total of 102 patients were included, 51 in each group. (i) SBP patients were more frequently treated by PPIs than controls (49 vs. 25%, P = 0.014). (ii) In group I, patients with (n = 25) and without (n = 26) PPIs had similar survival rates at 1 month (64.0 ± 9.6% vs. 59.4 ± 10.0%), 3 months (41.2 ± 10.2% vs. 44.6 ± 10.6%), and 1 year (26.6 ± 9.6% vs. 28.9 ± 10.1%), and similar median age at death (53 vs. 57 years). (iii) The reason for PPI use was inappropriate or undocumented in 34% of group I and II.

CONCLUSIONS

Proton pump inhibitors were more frequently used in SBP patients than in controls, but did not influence the prognosis in SBP. Overuse of PPIs was encountered in one-third of cirrhotic patients and should be avoided.

Alcohol consumption promotes the intestinal translocation of Streptococcus suis infections

Streptococcus suis is an emerging zoonotic agent. This study aimed to investigate whether S. suis is likely to translocate across the intestines of human hosts who have liver disease and/or consume alcohol. Both the alcoholism and cirrhosis models exhibited high mRNA expression of TGF and collagen1, but only the cirrhosis model had fibrosis in the liver. After both models were infected with S. suis, significantly different concentrations of S. suis were detected in the blood and brains of the alcoholism model (Blood: 36.4%; Brain: 31.8%) and the cirrhosis model (Blood: 62.5%; Brain: 62.5%) compared to the concentrations in the healthy mice (Blood: 15.4%; Brain: 0%). Trans-epithelial electrical resistance (TER) was used to examine the Caco-2 cells in the in vitro that had an S. suis infection combined with 1% ethanol. Although the ethanol did not influence the Caco-2 cells' barriers, it did rapidly decrease the barriers' TER value and then their E-cadherin compared to the infected Caco-2 cells without the ethanol treatment. Immunofluorescence also indicated that the barriers of the Caco-2 cells treated with ethanol were disrupted and that S. suis translocated from the apical to the basolateral side. This study demonstrated that alcohol consumption helped S. suis to translocate.

Immune and inflammatory pathways in NASH

Immune and inflammatory pathways have a central role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Both the innate and adaptive immune systems contribute to the development of NAFLD. Pathogen-associated molecular patterns and danger-associated molecular patterns are known to activate a variety of pattern-recognition receptors that result in inflammation. The key features of the immune system and inflammatory pathways in the development of NAFLD are discussed in this review.

Activated intestinal macrophages in patients with cirrhosis release NO and IL-6 that may disrupt intestinal barrier function

BACKGROUND & AIMS

Bacterial infections commonly occur in decompensated cirrhosis resulting from bacterial translocation from the intestine. We studied the role of intestinal macrophages and the epithelial barrier in cirrhosis.

METHODS

Forty-four patients with NASH/ASH cirrhosis (decompensated n=29, compensated n=15) and nineteen controls undergoing endoscopy were recruited. Serum was obtained and LPS and LBP levels determined. Intestinal macrophages were characterized by flow cytometry, immunohistochemistry, and nitric oxide (NO) production measured in supernatant of cultured duodenal samples. Quantitative RT-PCR was performed on duodenal biopsies assessing 84 inflammatory genes. Protein levels of cytokines/chemokines were assessed in serum and supernatant. The duodenal wall was assessed by electron microscopy, tight junction protein expression determined by RT-PCR, immunohistochemistry, and Western blot and, functional analysis performed by transepithelial resistance measurement and permeability studies.

RESULTS

Increased plasma LPS, LBP levels and higher numbers of duodenal CD33(+)/CD14(+)/Trem-1(+) macrophages, synthesizing iNOS and secreting NO were present in decompensated cirrhosis. Upregulation of IL-8, CCL2, CCL13 at the transcriptional level, and increased IL-8, and IL-6 were detected in supernatant and serum in cirrhosis. IL-6 and IL-8 co-localised with iNOS(+) and CD68(+), but not with CD11c(+) cells. Electron microscopy demonstrated an intact epithelial barrier. Increased Claudin-2 was detected by Western blot and immunohistochemistry, while decreased transepithelial resistance and increased duodenal permeability were detected in decompensated cirrhosis.

CONCLUSIONS

Our study shows the presence of activated CD14(+)Trem-1(+)iNOS(+) intestinal macrophages, releasing IL-6, NO, and increased intestinal permeability in patients with cirrhosis, suggesting that these cells may produce factors capable of enhancing permeability to bacterial products.

Low-level HIV viremia is associated with microbial translocation and inflammation

BACKGROUND

Decrease in HIV viral load (VL) is accompanied by decrease in microbial translocation (MT) and chronic inflammation, but the behavior of these markers in patients with HIV-VL <20 copies per milliliter is unknown. The aim of this study was to determine whether strict control of HIV-VL is associated with MT and chronic inflammation.

METHODS

Observational cross-sectional study.

INCLUSION CRITERIA

HIV patients receiving antiretroviral therapy and HIV-VL <200 copies per milliliter for more than 6 months.

EXCLUSION CRITERIA

chronic liver disease, active infection, or antibiotic consumption. Recruitment: patients who consecutively visited the outpatient clinic in November 2011. Primary endpoint: molecular MT as determined by detection in plasma of 16S ribosomal DNA. Secondary variables: lipopolysaccharide, soluble CD14, tumor necrosis factor α, and interleukin 6. Primary explanatory variable: HIV-VL (COBAS AmpliPrep/COBAS TaqMan HIV-1 test, version 2.0) with a detection limit of 20 copies per milliliter.

RESULTS

Fifty-two patients were included: 65% men, median age 45 years, HIV acquired predominantly through sex (75%), 40% Centers for Disease Control and Prevention stage C, and median CD4 lymphocyte count 552 cells per cubic millimeter (range, 126-1640 cells/mm). Molecular MT was observed in 46% and 18% of patients with low-level (20-200 copies/mL) and negative (<20 copies/mL) HIV-VL, respectively (P < 0.05). Plasma levels of inflammatory markers (tumor necrosis factor α and interleukin 6) were higher in patients with molecular MT (P < 0.01) and were not influenced for HIV-VL.

CONCLUSIONS

Patients with HIV infection receiving treatment and negative HIV-VL (<20 copies/mL) present less frequently MT than patients with low-level HIV viremias (20-200 copies/mL). MT is associated with higher levels of inflammation markers, independent of HIV-VL.

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.

The Relationship between Renal Dysfunction and Abnormalities of the Immune System in Patients with Decompensated Cirrhosis

In patients with advanced cirrhosis, not only hepatocellular carcinoma but also bacterial infections, such as spontaneous bacterial peritonitis (SBP) or pneumonia, are frequent clinical complications in such immune-compromised patients. These pathologies often progress to renal dysfunction, especially hepatorenal syndrome (HRS). The central pathology of HRS is splanchnic arterial vasodilation and hyperpermeability followed by bacterial translocation (BT). BT induces a severe inflammatory response in the peritoneal lymphoid tissue, with the activation of the immune systems and the long-lasting production of vasoactive mediators that can impair the circulatory function and cause renal failure. Recent studies report that the plasma amino acid imbalance appeared to be related to an abnormality of the immune system in patients with decompensated cirrhosis. This paper can provide a new approach for future studies of the pathology in cirrhotic patients with renal dysfunction.

Selective activation of Toll-like receptor 7 in activated hepatic stellate cells may modulate their profibrogenic phenotype

Cholestatic liver injury may activate HSCs (hepatic stellate cells) to a profibrogenic phenotype, contributing to liver fibrogenesis. We have previously demonstrated the involvement of TLR (Toll-like receptor) 7 in the pathogenesis of biliary atresia. In the present study we investigated the ability of TLR7 to modulate the profibrogenic phenotype in HSCs. Obstructive jaundice was associated with significant down-regulation of TLR7. Primary HSCs isolated from BDL (bile duct ligation) rats with obstructive jaundice exhibited reduced expression of TLR7 and increased expression of α-SMA (α-smooth muscle actin) and collagen-α1 compared with sham rats, reflecting HSC-mediated changes. Treatment of primary activated rat HSCs and rat T6 cells with CL075, a TLR7 and TLR8 ligand, significantly decreased expression of MCP-1 (monocyte chemotactic protein-1), TGF-β1 (transforming growth factor-β1), collagen-α1 and MMP-2 (matrix metalloproteinase-2), and inhibited cell proliferation and migration. In contrast, silencing TLR7 expression with shRNA (short hairpin RNA) in T6 cells effectively blocked the effects of CL075 stimulation, reversing the changes in MCP-1, TGF-β1 and collagen-α1 expression and accelerating cell migration. Our results indicate that obstructive jaundice is associated with down-regulation of TLR7 and up-regulation of profibrogenic gene expression in HSCs. Selective activation of TLR7 may modulate the profibrogenic phenotype in activated HSCs associated with cholestatic liver injury.

Interaction between intestinal dendritic cells and bacteria translocated from the gut in rats with cirrhosis

Cirrhosis with ascites is associated with a high rate of gut bacterial translocation (GBT) and spontaneous bacterial infections of enteric origin. We addressed the activation state and role of intestinal dendritic cells (DCs) in experimental ascitic cirrhosis and their relationship with GBT. Cirrhosis with ascites was CCl(4) induced in rats. To examine their activation state and functions, DCs (CD103(+) RT1B(+) CD3(-) CD45RA(-) ) were isolated from the intestinal lamina propria and mesenteric lymph nodes (MLNs), and the following parameters were determined by flow cytometry: surface antigen expression; spontaneous or lipopolysaccharide-stimulated tumor necrosis factor alpha (TNF-α) production; and in vitro capacity to phagocytose latex beads and to migrate toward the chemokine (C-C motif) ligand 21. GBT was defined as the growth of bacteria in MLNs culture. Bacterial DNA (Bact-DNA) in MLNs was identified by polymerase chain reaction. In rats with Bact-DNA in MLNs without GBT, intestinal and MLNs CD103(+) -DCs showed features of activation, expansion of the proinflammatory CD4(+) -DC subpopulation, augmented TNF-α production, and increased phagocytic and migratory capacities. In contrast, in rats with GBT, CD103(+) -DCs showed the absence of an activated phenotype, lowered TNF-α production, and relatively deficient phagocytosis and migration capacities. The CD103(+) -DC of rats without Bact-DNA in MLNs or GBT were similar to controls. In cirrhotic rats, bowel decontamination with antibiotics eliminated Bact-DNA in MLNs and GBT, normalized the activation state and functions of CD103(+) -DCs, and increased their TNF-α production.

CONCLUSION

In experimental cirrhosis with ascites, continuous pressure of gut bacteria shapes the phenotypic and functional profile of intestinal DCs to produce effects that range from their activation and enhanced functions to their exhaustion and tolerance.

The intestinal microbiome and the leaky gut as therapeutic targets in alcoholic liver disease

Alcoholic liver disease (ALD) encompasses hepatic steatosis, which may progress to alcoholic hepatitis, fibrosis, and cirrhosis. It remains a leading cause of morbidity and mortality in the US and worldwide. The severity of liver disease correlates with plasma levels of bacterial products in patients, and experimental ALD depends on the level of gut derived bacterial products in rodents. Since intestinal decontamination and deficiency of bacterial product receptors or their downstream signaling molecules protect from alcohol-induced liver disease, bacterial translocation (BT), qualitative, and quantitative changes of the enteric microbiome are considered as being of fundamental importance in the pathogenesis of ALD. Recent enhancements in diagnostic technologies provide a better insight into these shifts. This review highlights vital events in ALD such as BT, the importance of Toll-like receptor (TLR) signaling, intestinal bacterial overgrowth (IBO), and changes in the intestinal microbiome. Furthermore, a treatment trial section of patients reviews possible future options of therapy for ALD modifying the enteric microbiome.

Beta-adrenergic receptor 1 selective antagonism inhibits norepinephrine-mediated TNF-alpha downregulation in experimental liver cirrhosis

BACKGROUND

Bacterial translocation is a frequent event in cirrhosis leading to an increased inflammatory response. Splanchnic adrenergic system hyperactivation has been related with increased bacterial translocation. We aim at evaluating the interacting mechanism between hepatic norepinephrine and inflammation during liver damage in the presence of bacterial-DNA.

ANIMALS AND METHODS

Forty-six mice were included in a 16-week protocol of CCl(4)-induced cirrhosis. Laparotomies were performed at weeks 6, 10, 13 and 16. A second set of forty mice injected with a single intraperitoneal dose of CCl(4) was treated with saline, 6-hydroxidopamine, Nebivolol or Butoxamine. After 5 days, mice received E. coli-DNA intraperitoneally. Laparotomies were performed 24 hours later. Liver bacterial-DNA, norepinephrine, TNF-alpha, IL-6 and beta-adrenergic receptor levels were measured.

RESULTS

Bacterial-DNA translocation was more frequent in CCl(4)-treated animals compared with controls, and increased as fibrosis progressed. Liver norepinephrine and pro-inflammatory cytokines were significantly higher in mice with vs without bacterial-DNA (319.7 ± 120.6 vs 120.7 ± 68.6 pg/g for norepinephrine, 38.4 ± 6.1 vs 29.7 ± 4.2 pg/g for TNF-alpha, 41.8 ± 7.4 vs 28.7 ± 4.3 pg/g for IL-6). Only beta-adrenergic receptor-1 was significantly increased in treated vs control animals (34.6 ± 7.3 vs 12.5 ± 5.3, p=0.01) and correlated with TNF-alpha, IL-6 and norepinephrine hepatic levels in animals with bacterial-DNA. In the second set of mice, cytokine levels were increased in 6-hydroxidopamine and Nebivolol (beta-adrenergic receptor-1 antagonist) treated mice compared with saline. Butoxamine (beta-adrenergic receptor-2 antagonist) didn't inhibit liver norepinephrine modulation of pro-inflammatory cytokines.

CONCLUSIONS

Beta-adrenergic receptor-1 mediates liver norepinephrine modulation of the pro-inflammatory response in CCl(4)-treated mice with bacterial-DNA.