Nitric oxide and the hyperdynamic circulation in cirrhosis: is there a role for selective intestinal decontamination?

Association between endotoxemia and blood no in the portal circulation of cirrhotic patients: results of a pilot study

Pathophysiology of portal vein thrombosis (PVT) in cirrhosis is still not entirely understood. Elevated levels of lipopolysaccharides (LPS) in portal circulation are significantly associated with hypercoagulation, increased platelet activation and endothelial dysfunction. The aim of the study was to investigate if LPS was associated with reduced portal venous flow, the third component of Virchow's triad, and the underlying mechanism. Serum nitrite/nitrate, as a marker of nitric oxide (NO) generation, and LPS were measured in the portal and systemic circulation of 20 patients with cirrhosis undergoing transjugular intrahepatic portosystemic shunt (TIPS) procedure; portal venous flow velocity (PVV) was also measured in each patient and correlated with NO and LPS levels. Serum nitrite/nitrate and LPS were significantly higher in the portal compared to systemic circulation; a significant correlation was found between LPS and serum nitrite/nitrate (R = 0.421; p < 0.01). Median PVV before and after TIPS was 15 cm/s (6-40) and 31 cm/s (14-79), respectively. Correlation analysis of PVV with NO and LPS showed a statistically significant negative correlation of PVV with portal venous NO concentration (R = - 0.576; p = 0.020), but not with LPS. In vitro study with endothelial cells showed that LPS enhanced endothelial NO biosynthesis, which was inhibited by L-NAME, an inhibitor of NO synthase, or TAK-242, an inhibitor of TLR4, the LPS receptor; this effect was accomplished by up-regulation of eNOS and iNOS. The study shows that in cirrhosis, endotoxemia may be responsible for reduced portal venous flow via overgeneration of NO and, therefore, contribute to the development of PVT.

Gut dysbiosis, endotoxemia and clotting activation: A dangerous trio for portal vein thrombosis in cirrhosis

Liver cirrhosis (LC) is associated with portal venous thrombosis (PVT) in roughly 20% of cirrhotic patients but the underlying mechanism is still unclear. Low-grade endotoxemia by lipopolysaccharides (LPS), a component of outer gut microbiota membrane, is detectable in the portal circulation of LC and could predispose to PVT. LPS may translocate into systemic circulation upon microbiota dysbiosis-induced gut barrier dysfunction, that is a prerequisite for enhanced gut permeability and ensuing endotoxemia. Experimental and clinical studies provided evidence that LPS behaves a pro-thrombotic molecule so promoting clotting and platelet activation. Experiments conducted in the portal circulation of cirrhotic patients showed the existence of LPS-related enhanced thrombin generation as well as endothelial dysfunction, venous stasis, and platelet activation. The review will analyze 1) the pro-thrombotic role of endotoxemia in the context of LC 2) the biological plausibility linking endotoxemia with PVT and 3) the potentially interventional tools to lower endotoxemia and eventually hypercoagulation.

The effect of malnutrition on the infectious outcomes of hospitalized patients with cirrhosis: analysis of the 2011-2017 hospital data

BACKGROUND

In patients with cirrhosis, there is a clinical concern that the development of protein-calorie malnutrition will affect the immune system and predispose these patients to increased infectious outcomes.

AIMS

In this study, we evaluate the effects of malnutrition on the infectious outcomes of patients admitted with cirrhosis.

MATERIALS AND METHODS

This study used the 2011-2017 National Inpatient Sample to identify patients with cirrhosis. These patients were stratified using malnutrition (protein-calorie malnutrition, cachexia, and sarcopenia) and matched using age, gender, and race with 1:1 nearest neighbor matching method. The endpoints included mortality and infectious outcomes.

RESULTS

After matching, there were 96 842 malnutrition-present cohort and equal number of controls. In univariate analysis, the malnutrition cohort had higher hospital mortality [10.40 vs. 5.04% P < 0.01, odds ratio (OR) 2.18, 95% confidence interval (CI) 2.11-2.26]. In multivariate models, malnutrition was associated with increased mortality [P < 0.01, adjusted odds ratio (aOR) 1.32, 95% CI 1.27-1.37] and infectious outcomes, including sepsis (P < 0.01, aOR 1.94, 95% CI 1.89-2.00), pneumonia (P < 0.01, aOR 1.68, 95% CI 1.63-1.73), UTI (P < 0.01, aOR 1.39, 95% CI 1.35-1.43), cellulitis (P < 0.01, aOR 1.09, 95% CI 1.05-1.13), cholangitis (P < 0.01, aOR 1.39, 95% CI 1.26-1.55), and clostridium difficile (P < 0.01, aOR 2.11, 95% CI 1.92-2.31).

CONCLUSION

The results of this study indicate that malnutrition is an independent risk factor of hospital mortality and local/systemic infections in patients admitted with cirrhosis.

MiR-21 mediates the protection of kaempferol against hypoxia/reoxygenation-induced cardiomyocyte injury via promoting Notch1/PTEN/AKT signaling pathway

Kaempferol, a natural flavonoid compound, possesses potent myocardial protective property in ischemia/reperfusion (I/R), but the underlying mechanism is not well understood. The present study was aimed to explore whether miR-21 contributes to the cardioprotective effect of kaempferol on hypoxia/reoxygenation (H/R)-induced H9c2 cell injury via regulating Notch/phosphatase and tensin homologue (PTEN)/Akt signaling pathway. Results revealed that kaempferol obviously attenuates H/R-induced the damages of H9c2 cells as evidence by the up-regulation of cell viability, the down-regulation of lactate dehydrogenase (LDH) activity, the reduction of apoptosis rate and pro-apoptotic protein (Bax) expression, and the increases of anti-apoptotic protein (Bcl-2) expression. In addition, kaempferol enhanced miR-21 level in H9c2 cells exposed to H/R, and inhibition of miR-21 induced by transfection with miR-21 inhibitor significantly blocked the protection of kaempferol against H/R-induced H9c2 cell injury. Furthermore, kaempferol eliminated H/R-induced oxidative stress and inflammatory response as illustrated by the decreases in reactive oxygen species generation and malondialdehyde content, the increases in antioxidant enzyme superoxide dismutase and glutathione peroxidase activities, the decreases in pro-inflammatory cytokines interleukin (IL)-1β, IL-8 and tumor necrosis factor-alpha levels, and an increase in anti-inflammatory cytokine IL-10 level, while these effects of kaempferol were all reversed by miR-21 inhibitor. Moreover, results elicited that kaempferol remarkably blocks H/R-induced the down-regulation of Notch1 expression, the up-regulation of PTEN expression, and the reduction of P-Akt/Akt, indicating that kaempferol promotes Notch1/PTEN/AKT signaling pathway, and knockdown of Notch1/PTEN/AKT signaling pathway induced by Notch1 siRNA also abolished the protection of kaempferol against H/R-induced the damage of H9c2 cells. Notably, miR-21 inhibitor alleviated the promotion of kaempferol on Notch/PTEN/Akt signaling pathways in H9c2 cells exposed to H/R. Taken together, these above findings suggested thatmiR-21 mediates the protection of kaempferol against H/R-induced H9c2 cell injuryvia promoting Notch/PTEN/Akt signaling pathway.

Gut Microbiome-based Therapeutics in Liver Cirrhosis: Basic Consideration for the Next Step

Infections account for significant morbidity and mortality in liver cirrhosis and most are related to the gut microbiome. Fecal dysbiosis, characterized by an overgrowth of potentially pathogenic bacteria and a decrease in autochthonous non-pathogenic bacteria, becomes prominent with the progression of liver cirrhosis. In cirrhotic patients, disruption of the intestinal barrier causes intestinal hyperpermeability (i.e. leaky gut), which is closely related to gut dysmotility, dysbiosis and small intestinal bacterial overgrowth and may induce pathological bacterial translocation. Although the involved microbial taxa are somewhat different between the cirrhotic patients from the East and the West, the common manifestation of a shortage of bacteria that contribute to the production of short-chain fatty acids and secondary bile acids may facilitate intestinal inflammation, leaky gut and gut dysbiosis. Translocated endotoxin and bacterial DNA are capable of provoking potent inflammation and affecting the metabolic and hemodynamic systems, which may ultimately enhance the progression of liver cirrhosis and its various complications, such as hepatic encephalopathy (HE), variceal bleeding, infection and renal disturbances. Among studies on the microbiome-based therapeutics, findings of probiotic effects on HE have been contradictory in spite of several supportive results. However, the effects of synbiotics and prebiotics are substantially documented. The background of their effectiveness should be evaluated again in relation to the cirrhosis-related changes in gut microbiome and their metabolic effects. Strict indications for the antibiotic rifaximin remain unestablished, although its effect is promising, improving HE and other complications with little influence on microbial populations. The final goal of microbiome-based therapeutics is to adjust the gut-liver axis to the maximal benefit of cirrhotic patients, with the aid of evolving metagenomic and metabolomic analyses.

CT Scan Does Not Differentiate Patients with Hepatopulmonary Syndrome from Other Patients with Liver Disease

Background

Hepatopulmonary syndrome (HPS) is defined by liver dysfunction, intrapulmonary vascular dilatations, and impaired oxygenation. The gold standard for detection of intrapulmonary vascular dilatations in HPS is contrast echocardiography. However, two small studies have suggested that patients with HPS have larger segmental pulmonary arterial diameters than both normal subjects and normoxemic subjects with cirrhosis, when measured by CT. We sought to compare CT imaging-based pulmonary vasodilatation in patients with HPS, patients with liver dysfunction without HPS, and matching controls on CT imaging.

Methods

We performed a retrospective cohort study at two quaternary care Canadian HPS centers. We analyzed CT thorax scans in 23 patients with HPS, 29 patients with liver dysfunction without HPS, and 52 gender- and age-matched controls. We measured the artery-bronchus ratios (ABRs) in upper and lower lung zones, calculated the “delta ABR” by subtracting the upper from the lower ABR, compared these measurements between groups, and correlated them with clinically relevant parameters (partial pressure of arterial oxygen, alveolar-arterial oxygen gradient, macroaggregated albumin shunt fraction, and diffusion capacity). We repeated measurements in patients with post-transplant CTs.

Results

Patients had significantly larger lower zone ABRs and delta ABRs than controls (1.20 +/- 0.19 versus 0.98 +/- 0.10, p<0.01; and 0.12 +/- 0.17 versus -0.06 +/- 0.10, p<0.01, respectively). However, there were no significant differences between liver disease patients with and without HPS, nor any significant correlations between CT measurements and clinically relevant parameters. There were no significant changes in ABRs after liver transplantation (14 patients).

Conclusions

Basilar segmental artery-bronchus ratios are larger in patients with liver disease than in normal controls, but this vasodilatation is no more severe in patients with HPS. CT does not distinguish patients with HPS from those with uncomplicated liver disease.

Immunomodulating effects of antibiotics used in the prophylaxis of bacterial infections in advanced cirrhosis

The use of norfloxacin either as primary or secondary prophylaxis of bacterial infections in advanced cirrhosis has improved patient’s survival. This may be explained not only due to a significant decrease in the number of infections, but also because of a direct immunomodulatory effect. Selective intestinal decontamination with norfloxacin reduces translocation of either viable bacteria or bacteria-driven products from the intestinal lumen. In addition, norfloxacin directly modulates the systemic inflammatory response. The pro-inflammatory cytokine profile secreted by neutrophils from these patients shows a close, significant, and inverse correlation with serum norfloxacin levels. Similar effects have been described with other quinolones in different clinical conditions. Although the underlying mechanisms are not well defined for most of the antibiotics, the pathways triggered for norfloxacin to induce such immunomodulatory effects involve the down-regulation of pro-inflammatory inducible nitric oxide synthase, cyclooxygenase-2, and NF-κB and the up-regulation of heme-oxygenase 1 and IL-10 expression. The knowledge of these immunomodulatory effects, additional to their bactericidal role, improves our comprehension of the interaction between antibiotics and the cellular host response and offer new possibilities for the development of new therapeutic strategies to manage and prevent bacterial infections in cirrhosis.

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.

Hepatic hemodynamic changes during liver transplantation: A review

Liver transplantation is performed in the recent decades with great improvements not only technically but also conceptually. However, there is still lack of consensus about the optimal hemodynamic characteristics during liver transplantation. The representative hemodynamic parameters include portal vein pressure, portal vein flow, and hepatic venous pressure gradient; however, there are still others potential valuable parameters, such as total liver inflow and hepatic artery flow. All the parameters are correlated closely and some internal modulating mechanisms, like hepatic arterial buffer response, occur to maintain stable hepatic inflow. To distinguish the unique importance of each hepatic and systemic parameter in different states during liver transplantation, we reviewed the published data and also conducted two transplant cases with different surgical strategies applied to achieve ideal portal inflow and pressure.

The gut microbiota and the liver: implications for clinical practice

While a central role for the microbiota in the precipitation of infectious and non-infectious complications of liver disease has been long established, evidence for a more fundamental role in the etiology of several liver diseases continues to accumulate. However, though progress is rapidly occurring in this area, the definitive delineation of the precise relevance of changes in the microbiota to various forms and stages of liver disease is still far from complete. While high quality clinical evidence supports the use of antibiotic therapy, in the management of hepatic encephalopathy, spontaneous bacterial peritonitis and other infectious complications, how these interventions impact on the microbiota and microbiota-host interactions has not been clearly defined. Although probiotics and even, perhaps, fecal transplantation hold promise in the management of liver disease, and the potential impact of probiotics is supported by a considerable amount of laboratory data, high-quality clinical evidence is scanty.

VSL#3 ® probiotic therapy does not reduce portal pressures in patients with decompensated cirrhosis

BACKGROUND & AIMS

In patients with decompensated cirrhosis, bacterial translocation can contribute to splanchnic vasodilatation, decreased effective circulating volume, and portal hypertension. The primary objective of this randomized, double blind placebo controlled trial was to evaluate the effect of the probiotic VSL#3(®) on the hepatic venous pressure gradient (HVPG).

METHODS

Seventeen patients with decompensated cirrhosis and an HVPG of ≥ 10 mmHg were randomized to receive 2 months of VSL#3(®) or an identical placebo. HVPG, endotoxin, interleukin (IL)-6, IL-8, IL-10, renin, aldosterone, nitric oxide and stool microbiota were measured at baseline and study end.

RESULTS

Two of the 17 patients were taken off the trial before completion (one for alcohol abuse and the second for SBP - both in placebo arm). Data were analysed on the remaining 15 patients. The median model for end-stage liver disease score was 12, and 80% of patients had Child Pugh B disease. The treatment arm had a greater decrease in HVPG from baseline to study end than the placebo arm (median change from baseline -11.6% vs +2.8%), although this reduction was not statistically significant in either group. There was a significant reduction in the plasma aldosterone level in the VSL#3(®) group, but no significant changes in the other measured parameters, including the stool microflora analysis.

CONCLUSIONS

Within the limitations of our sample size, VSL#3(®) therapy does not appear to have a significant impact on portal pressure reduction in patients with decompensated cirrhosis.

Cardiac dysfunction in cirrhosis - does adrenal function play a role? A hypothesis

Cirrhotic cardiomyopathy (CCM), a condition of unknown pathogenesis, is characterized by suboptimal ventricular contractile response to stress, diastolic dysfunction and QT interval prolongation. It is most often found in patients with advanced cirrhosis. It is clinically relevant during stressful conditions, such as sepsis, bleeding and surgery. CCM reverses after liver transplantation and potentially has a role in the pathogenesis of hepatorenal syndrome. In adrenal insufficiency (AI), cardiac dysfunction is a feature with low ejection fraction, decreased left ventricular chamber size and electrocardiographic abnormalities, including QT interval prolongation. With optimal diagnostic tests, AI is present in approximately 10% of patients with cirrhosis, particularly in those with advanced disease. Down-regulation and decreased number of beta-adrenergic receptors, and high catecholamine levels are common to both cardiac conditions. Thus, AI may play a role in CCM. Steroid replacement therapy reverses cardiac changes in AI, and may do so for CCM, with important therapeutic implications; this needs formal evaluation.

Intestinal permeability in patients with chronic liver diseases: Its relationship with the aetiology and the entity of liver damage

BACKGROUND

Alteration in intestinal permeability may be an important factor in the pathogenesis of both the progression of some chronic liver diseases and the onset of some complications in patients with liver cirrhosis.

AIMS

To investigate the relationships between intestinal permeability, portal hypertension, alcohol use, plasma levels of pro-inflammatory cytokines, and nitric oxide, expressed as s-nitrosothiols, and nitrite levels in patients with various types and degrees of chronic liver diseases.

METHODS

134 healthy volunteers and 83 patients with chronic liver damage entered the study. Intestinal permeability was assessed with the lactulose/mannitol test. Plasma levels of tumour necrosis factor-alpha, interleukin-6, and nitrite and total s-nitrosothiols were determined.

RESULTS

Intestinal permeability was altered in patients with advanced liver disease and impaired in 15-35% of patients without cirrhosis. Independent factors for intestinal permeability alteration were age, portal hypertension, alcohol use, and diabetes. Plasma levels of inflammatory cytokines and nitrosothiols were significantly higher in patients with altered intestinal permeability.

CONCLUSIONS

An intestinal permeability evaluation in patients with chronic liver diseases might clarify the significance of intestinal permeability in the pathophysiology of both the progression of liver damage, and the occurrence of complications that accompany liver cirrhosis.

Intestinal permeability in cirrhotic patients with and without spontaneous bacterial peritonitis: is the ring closed?

OBJECTIVES

Impaired intestinal permeability (IP) may have a role in the pathogenesis of ascites and in spontaneous bacterial peritonitis (SBP) in patients with liver cirrhosis (LC). The aim of this study was to assess IP in LC patients with respect to healthy controls.

METHODS

IP was evaluated by the (51)Cr-ethylenediaminetetraacetic acid ((51)Cr-EDTA) permeability test in 52 LC patients and in 48 sex- and age-matched controls. The presence of (51)Cr-EDTA was also evaluated in ascitic fluid after therapeutic paracentesis in all LC patients with ascites.

RESULTS

An altered IP was found in 45% of LC patients compared with 4% of controls (P<0.00001). IP impairment was significantly associated with Child-Pugh status (75% of Child C patients vs. 39% of Child B and 22% of Child A patients), with the presence of ascites (60% in ascitic patients vs. 31% in nonascitic patients), and with a history of SBP (100% of patients with SBP vs. 50% of those without SBP). (51)Cr-EDTA was present in all ascitic samples obtained from patients with SBP compared with 22% of patients without SBP.

CONCLUSIONS

IP derangement was a common finding in LC, especially in patients with more advanced disease (presence of ascites and history of SBP). The presence of (51)Cr-EDTA in ascites in patients with SBP suggests an altered permeability of splancnic vessels and/or peritoneal membranes. Further studies are required to assess (51)Cr-EDTA urine and ascite cutoffs to set up SBP preventive strategies.

Adverse gastrointestinal effects of arginine and related amino acids

Oral supplements of arginine and citrulline increase local nitric oxide (NO) production in the small intestine and this may be harmful under certain circumstances. Gastrointestinal toxicity was therefore reviewed with respect to the intestinal physiology of arginine, citrulline, ornithine, and cystine (which shares the same transporter) and the many clinical trials of supplements of the dibasic amino acids or N-acetylcysteine (NAC). The human intestinal dibasic amino acid transport system has high affinity and low capacity. L-arginine (but not lysine, ornithine, or D-arginine) induces water and electrolyte secretion that is mediated by NO, which acts as an absorbagogue at low levels and as a secretagogue at high levels. The action of many laxatives is NO mediated and there are reports of diarrhea following oral administration of arginine or ornithine. The clinical data cover a wide span of arginine intakes from 3 g/d to>100 g/d, but the standard of reporting adverse effects (e.g. nausea, vomiting, and diarrhea) was variable. Single doses of 3-6 g rarely provoked side effects and healthy athletes appeared to be more susceptible than diabetic patients to gastrointestinal symptoms at individual doses>9 g. This may relate to an effect of disease on gastrointestinal motility and pharmacokinetics. Most side effects of arginine and NAC occurred at single doses of >9 g in adults (>140 mg/kg) often when part of a daily regime of approximately>30 g/d (>174 mmol/d). In the case of arginine, this compares with the laxative threshold of the nonabsorbed disaccharide alcohol, lactitol (74 g or 194 mmol). Adverse effects seemed dependent on the dosage regime and disappeared if divided doses were ingested (unlike lactitol). Large single doses of poorly absorbed amino acids seem to provoke diarrhea. More research is needed to refine dosage strategies that reduce this phenomenon. It is suggested that dipeptide forms of arginine may meet this criterion.

Allopurinol, oxidative stress and intestinal permeability in patients with cirrhosis: an open-label pilot study

BACKGROUND

Cirrhosis is associated with intestinal barrier failure, related in part to enterocytes oxidative damage via xanthine oxidase overactivity. Experimentally, allopurinol, a xanthine oxidase inhibitor, reduces enterocytes' damage and bacterial translocation.

AIM

To assess the short-term effects of allopurinol on intestinal permeability, oxidative stress and endotoxin-dependent cytokines in patients with cirrhosis.

METHODS

Nineteen patients with cirrhosis, in a stable condition (age: 56 years; Child A/B/C: 6/7/6; ascites: 12; alcoholic cirrhosis: 16/19; abstinence >2 weeks), were included. At baseline and day 10 of allopurinol 400 mg/day, intestinal permeability [lactulose/mannitol (Lac/Man) ratio test], oxidative stress (serum malondialdehyde), as well as TNF-soluble receptor-1, IL-6 and lipopolysaccharide-binding protein (which reflects exposition to endotoxin) were measured.

RESULTS

Malondialdehyde decreased significantly (-23%, P<0.05), whereas no effects were seen on intestinal permeability and the endotoxin-associated systemic inflammatory response. At baseline, portal pressure correlated to the Lac/Man ratio (r=0.55, P<0.02). At day 10, changes in malondialdehyde correlated to changes in the Lac/Man ratio (r=0.51, P<0.05).

CONCLUSIONS

A 10-day course of allopurinol in patients with cirrhosis is associated with a significant reduction in oxidative stress but no effect on intestinal permeability and inflammatory markers. Whether intestinal damage in cirrhosis can be accessible to antioxidant therapy requires further study.