No difference in portal and hepatic venous bacterial DNA in patients with cirrhosis undergoing transjugular intrahepatic portosystemic shunt insertion

Proton pump inhibitor treatment aggravates bacterial translocation in patients with advanced cirrhosis and portal hypertension

IMPORTANCE

Long-term prescription of proton pump inhibitors (PPIs) in patients with cirrhosis is common practice. However, in recent years, several observational studies have reported increased complications and negative prognostic effects of PPI treatment in these patients. Judging the significance of these associations is complicated by the fact that a plausible underlying pathomechanism has not been identified so far. In the present study, we address this important issue by investigating the impact of PPI treatment on subclinical bacterial translocation from the gut into the blood stream in patients with advanced cirrhosis and portal hypertension. Indeed, we report significantly aggravated bacterial translocation in cirrhosis patients receiving PPI treatment. This finding is highly relevant, as bacterial translocation is known to promote the development of complications and impair prognosis in patients with cirrhosis. Hence, the present study could establish a plausible link between PPI treatment and adverse effects in cirrhosis.

Circulating microbiome in patients with portal hypertension

Portal hypertension (PH) in liver cirrhosis leads to increased gut permeability and the translocation of bacteria across the gut-liver axis. Microbial DNA has recently been detected in different blood compartments; however, this phenomenon has not been thoroughly analyzed in PH. This study aimed to explore circulating bacterial DNA signatures, inflammatory cytokines, and gut permeability markers in different blood compartments (peripheral and hepatic veins) of patients with cirrhosis and PH. The 16S rRNA blood microbiome profiles were determined in 58 patients with liver cirrhosis and 46 control patients. Taxonomic differences were analyzed in relation to PH, liver function, inflammatory cytokines, and gut permeability markers. Circulating plasma microbiome profiles in patients with cirrhosis were distinct from those of the controls and were characterized by enrichment of Comamonas, Cnuella, Dialister, Escherichia/Shigella, and Prevotella and the depletion of Bradyrhizobium, Curvibacter, Diaphorobacter, Pseudarcicella, and Pseudomonas. Comparison of peripheral and hepatic vein blood compartments of patients with cirrhosis did not reveal differentially abundant taxa. Enrichment of the genera Bacteroides, Escherichia/Shigella, and Prevotella was associated with severe PH (SPH) in both blood compartments; however, circulating microbiome profiles could not predict PH severity. Escherichia/Shigella and Prevotella abundance was correlated with IL-8 levels in the hepatic vein. In conclusion, we demonstrated a distinct circulating blood microbiome profile in patients with cirrhosis, showing that specific bacterial genera in blood are marginally associated with SPH, Model for End-Stage Liver Disease score, and inflammation biomarkers; however, circulating microbial composition failed to predict PH severity.

No protective benefits of low dose acute L-glutamine supplementation on small intestinal permeability, epithelial injury and bacterial translocation biomarkers in response to subclinical exertional-heat stress: A randomized cross-over trial

Exertional heat stress disrupts gastrointestinal permeability and, through subsequent bacterial translocation, can result in potentially fatal exertional heat stroke. Glutamine supplementation is a potential countermeasure although previously validated doses are not universally well tolerated. Ten males completed two 80-minute subclinical exertional heat stress tests (EHSTs) following either glutamine (0.3 g kg FFM^-1) or placebo supplementation. Small intestinal permeability was assessed using the lactulose/rhamnose dual sugar absorption test and small intestinal epithelial injury using Intestinal Fatty-Acid Binding Protein (I-FABP). Bacterial translocation was assessed using the total 16S bacterial DNA and Bacteroides/total 16S DNA ratio. The glutamine bolus was well tolerated, with no participants reporting symptoms of gastrointestinal intolerance. Small intestinal permeability was not influenced by glutamine supplementation (p = 0.06) although a medium effect size favoring the placebo trial was observed (d = 0.73). Both small intestinal epithelial injury (p < 0.01) and Bacteroides/total 16S DNA (p = 0.04) increased following exertional heat stress, but were uninfluenced by glutamine supplementation. Low-dose acute oral glutamine supplementation does not protect gastrointestinal injury, permeability, or bacterial translocation in response to subclinical exertional heat stress.

Reliability of gastrointestinal barrier integrity and microbial translocation biomarkers at rest and following exertional heat stress

PURPOSE

Exertional heat stress adversely distrupts (GI) barrier integrity and, through subsequent microbial translocation (MT), negativly impacts health. Despite widespread application, the temporal reliability of popular GI barrier integity and MT biomarkers is poorly characterised.

METHOD

Fourteen males completed two 80-min exertional heat stress tests (EHST) separated by 7-14 days. Venous blood was drawn pre, immediately- and 1-hr post both EHSTs. GI barrier integrity was assessed using the serum Dual-Sugar Absorption Test (DSAT), Intestinal Fatty-Acid-Binding Protein (I-FABP) and Claudin-3 (CLDN-3). MT was assessed using plasma Lipopolysaccharide Binding Protein (LBP), total 16S bacterial DNA and Bacteroides DNA.

RESULTS

No GI barrier integrity or MT biomarker, except absolute Bacteroides DNA, displayed systematic trial order bias (p ≥ .05). I-FABP (trial 1 = Δ 0.834 ± 0.445 ng ml^-1 ; trial 2 = Δ 0.776 ± 0.489 ng ml^-1 ) and CLDN-3 (trial 1 = Δ 0.317 ± 0.586 ng ml^-1 ; trial 2 = Δ 0.371 ± 0.508 ng ml^-1 ) were increased post-EHST (p ≤ .01). All MT biomarkers were unchanged post-EHST. Coefficient of variation and typical error of measurement post-EHST were: 11.5% and 0.004 (ratio) for the DSAT 90-min postprobe ingestion; 12.2% and 0.004 (ratio) at 150-min postprobe ingestion; 12.1% and 0.376 ng ml^-1 for I-FABP; 4.9% and 0.342 ng ml^-1 for CLDN-3; 9.2% and 0.420 µg ml^-1 for LBP; 9.5% and 0.15 pg µl^-1 for total 16S DNA; and 54.7% and 0.032 for Bacteroides/total 16S DNA ratio.

CONCLUSION

Each GI barrier integrity and MT translocation biomarker, except Bacteroides/total 16S ratio, had acceptable reliability at rest and postexertional heat stress.

Changes in the vaginal microbiota following antibiotic treatment for Mycoplasma genitalium, Chlamydia trachomatis and bacterial vaginosis

The human vagina harbor a rich microbiota. The optimal state is dominated by lactobacilli that help to maintain health and prevent various diseases. However, the microbiota may rapidly change to a polymicrobial state that has been linked to a number of diseases. In the present study, the temporal changes of the vaginal microbiota in patients treated for sexually transmitted diseases or bacterial vaginosis (BV) and in untreated controls were studied for 26 days. The patients included 52 women treated with azithromycin, tetracyclines or moxifloxacin for present or suspected infection with Chlamydia trachomatis or Mycoplasma genitalium. Women with concurrent BV were also treated with metronidazole. The controls were 10 healthy women of matching age. The microbiota was analyzed by 16S rRNA gene deep sequencing, specific qPCRs and microscopy. There was generally good correlation between Nugent score and community state type (CST) and qPCR confirmed the sequencing results. By sequencing, more than 600 different taxa were found, but only 33 constituted more than 1 ‰ of the sequences. In both patients and controls the microbiota could be divided into three different community state types, CST-I, CST-III and CST-IV. Without metronidazole, the microbiota remained relatively stable regarding CST although changes were seen during menstrual periods. Administration of metronidazole changed the microbiota from CST-IV to CST-III in approximately 50% of the treated patients. In contrast, the CST was generally unaffected by azithromycin or tetracyclines. In 30% of the BV patients, Gardnerella vaginalis was not eradicated by metronidazole. The majority of women colonized with Ureaplasma parvum remained positive after azithromycin while U. urealyticum was eradicated.

Kinetics of the soluble urokinase plasminogen activator receptor (suPAR) in cirrhosis

Background

The soluble urokinase plasminogen activator receptor (suPAR) is related to hepatic inflammation and fibrosis and has been suggested to participate in the development of liver cirrhosis. Therefore, the aim of the current study was to measure the concentration of suPAR in the hepatic vein of cirrhotic patients during a liver vein catheterization to identify a possible hepatic suPAR generation. Furthermore, we explored if suPAR levels were associated with the degree of cirrhosis and liver dysfunction.

Methods and patients

We included 105 cirrhotic patients and 19 liver-healthy controls. Blood was sampled from the hepatic vein and the femoral artery and suPAR was measured by enzyme-linked immunosorbent assay.

Results

We identified significantly higher median suPAR concentrations among the cirrhotic patients (7.2 ng/ml in the hepatic vein; 6.8 ng/ml in the femoral artery) compared to the controls (2.6 ng/ml, respectively, p-values <0.001). However, the median hepatic suPAR formation was 0.0 ng/ml in both groups. We observed significantly increasing suPAR levels according to higher Child classes (4.5 ng/ml, 6.9 ng/ml and 9.0 ng/ml, Child A, B, C respectively; p-value<0.001), and significantly higher median suPAR concentrations in patients with ascites versus patients without ascites (8.1 ng/ml versus 5.3 ng/ml, respectively, p-value<0.001). suPAR levels were significantly related to bilirubin (r = 0.48, p<0.001), the hepatic venous pressure gradient (r = 0.39, p<0.001), the cardiac index (r = 0.24, p = 0.02) and the plasma volume (r = 0.33, p = 0.001), whereas suPAR levels were significantly inversely related to albumin (r = -0.59, p<0.001), plasma coagulation factors (r-0.39, p<0.001), the mean arterial pressure (r = -0.28, p = 0.004), the systemic vascular resistance (r = 0.26, p = 0.007), the indocyanine green clearance (r = -0.51, p<0,001) and the galactose elimination capacity (r = -0.39, p<0.001).

Conclusion

We identified elevated suPAR concentration in cirrhotic patients, which correlated significantly with the degree of cirrhosis and liver failure, but we were not able to demonstrate hepatic suPAR generation per se. This suggests that further investigations of the source of suPAR in cirrhotic patients need to be undertaken.

The bacterial microbiota in first-void urine from men with and without idiopathic urethritis

Background

Non-gonococcal urethritis (NGU) is a common syndrome in men. NGU may have several causes, but many cases are caused by sexually transmitted infections that may also cause complications in their female partners. Chlamydia trachomatis and Mycoplasma genitalium are the most common causes of NGU, but in up to 35% of the cases, none of the known viral or bacterial causes are found. Traditionally, pathogens have been detected using various culture techniques that may not identify all species present in the urethra. To address this, we used culture-independent methods for analysis of the male urethral microbiota.

Methods

This case-control study analysed first void urine samples, collected at STD clinics in Stockholm, Sweden from men with idiopathic urethritis (IU), i.e. negative for Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, Ureaplasma urealyticum, Trichomonas vaginalis, adenovirus, and herpes simplex virus type 1 and -2 together with samples from men without urethritis. Forty-six controls and 39 idiopathic urethritis patients were analysed.

Results

The microbiota was highly diverse: None of the 302 operational taxonomic units (OTUs) found in negative controls and IU patients were found in all of the samples or even in all of the samples in one group. More than 50% of the OTUs were only found in one or two of the total of 85 samples. Still the most dominant 1/6 of the genera constituted 79% of the sequences.

Hierarchical clustering in a heatmap showed no specific clustering of patients or controls.

A number of IU patient samples were dominated by a single genus previously related to urethritis (Gardnerella, Haemophilus, Ureaplasma).

Conclusion

The male urethra contain a very diverse composition of bacteria, even in healthy controls. NGU may be caused by a number of different bacteria but more studies including a higher number of samples are needed for elucidation of the role of each species.

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.

Transjugular intrahepatic portosystemic shunt: impact on systemic hemodynamics and renal and cardiac function in patients with cirrhosis

Transjugular intrahepatic portosystemic shunt (TIPS) alleviates portal hypertension and possibly increases central blood volume (CBV). Moreover, renal function often improves; however, its effects on cardiac function are unclear. The aims of our study were to examine the effects of TIPS on hemodynamics and renal and cardiac function in patients with cirrhosis. In 25 cirrhotic patients, we analyzed systemic, cardiac, and splanchnic hemodynamics by catheterization of the liver veins and right heart chambers before and 1 wk after TIPS. Additionally, we measured renal and cardiac markers and performed advanced echocardiography before, 1 wk after, and 4 mo after TIPS. CBV increased significantly after TIPS (+4.6%, P < 0.05). Cardiac output (CO) increased (+15.3%, P < 0.005) due to an increase in stroke volume (SV) (+11.1%, P < 0.005), whereas heart rate (HR) was initially unchanged. Cardiopulmonary pressures increased after TIPS, whereas copeptin, a marker of vasopressin, decreased (-18%, P < 0.005) and proatrial natriuretic peptide increased (+52%, P < 0.0005) 1 wk after TIPS and returned to baseline 4 mo after TIPS. Plasma neutrophil gelatinase-associated lipocalin, renin, aldosterone, and serum creatinine decreased after TIPS (-36%, P < 0.005; -65%, P < 0.05; -90%, P < 0.005; and -13%, P < 0.005, respectively). Echocardiography revealed subtle changes in cardiac function after TIPS, although these were within the normal range. TIPS increases CBV by increasing CO and SV, whereas HR is initially unaltered. These results indicate an inability to increase the heart rate in response to a hemodynamic challenge that only partially increases CBV after TIPS. These changes, however, are sufficient for improving renal function. NEW & NOTEWORTHY For the first time, we have combined advanced techniques to study the integrated effects of transjugular intrahepatic portosystemic shunt (TIPS) in cirrhosis. We showed that TIPS increases central blood volume (CBV) through improved cardiac inotropy. Advanced echocardiography demonstrated that myocardial function was unaffected by the dramatic increase in preload after TIPS. Finally, renal function improved due to the increase in CBV. Recognition of these physiological changes significantly contributes to our clinical understanding of TIPS.

Effects of transjugular intrahepatic portosystemic shunt (TIPS) on blood volume distribution in patients with cirrhosis

BACKGROUND

Cirrhosis is accompanied by portal hypertension with splanchnic and systemic arterial vasodilation, and central hypovolaemia. A transjugular intrahepatic portosystemic shunt (TIPS) alleviates portal hypertension, but also causes major haemodynamic changes.

AIMS

To investigate effects of TIPS on regional blood volume distribution, and systemic haemodynamics.

METHODS

Thirteen cirrhotic patients had their regional blood volume distribution determined with gamma-camera technique before and after TIPS. Additionally, we measured systemic haemodynamics during liver vein and right heart catheterization. Central and arterial blood volume (CBV) and cardiac output (CO) were determined with indicator dilution technique.

RESULTS

After TIPS, the thoracic blood volume increased (+10.4% of total blood volume (TBV), p<0.01), whereas the splanchnic blood volume decreased (-11.9% of TBV, p<0.001). CO increased (+22%, p<0.0001), and systemic vascular resistance decreased (-26%, p<0.001), whereas CBV did not change. Finally, right atrial pressure and mean pulmonary artery pressure increased after TIPS (+50%, p<0.005; +40%, p<0.05, respectively).

CONCLUSIONS

TIPS restores central hypovolaemia by an increase in thoracic blood volume and alleviates splanchnic vascular congestion. In contrast, CBV seems unaltered. The improvement in central hypovolaemia is therefore based on an increase in thoracic blood volume that includes both the central venous and arterial blood volume. This is supported by an increase in preload, combined with a decrease in afterload.

Bacterial translocation markers in liver cirrhosis

Bacterial translocation (BT) is an important mechanism in the development of infection in liver cirrhosis. The migration and colonization of bacteria and/or bacterial products from the bowel to mesenteric lymph nodes is a controlled process in healthy persons. Increased intestinal permeability, bacterial overgrowth and defect of gut-associated lymphatic tissue promote impaired BT in cirrhotics. We reviewed the reports on markers used for the evaluation of BT published between 1987 and 2016. We focused on the clinical consequences of BT in cirrhosis, as indicated by the values of the BT markers. Patients with cirrhosis are reported to have elevated levels of surrogate markers associated with BT compared with controls. The most widely used BT parameters are C-reactive protein, procalcitonin, bacterial DNA, endotoxin or lipopolysaccharide, lipopolysaccharide binding protein, calprotectin, and bactericidal/permeability increasing protein. High levels of these factors in serum and/or ascitic fluid in humans may be associated with advanced liver disease, hemodynamic instability, high levels of proinflammatory cytokines, susceptibility to the development of severe or recurrent infections, acute-on-chronic liver failure, hepatic encephalopathy, hepatorenal syndrome and poor prognosis during follow up. In conclusion, high levels of BT markers are associated with a high inflammatory response, increased complications of liver cirrhosis and occasionally high fatality rates.

The soluble mannose receptor is released from the liver in cirrhotic patients, but is not associated with bacterial translocation

BACKGROUND & AIMS

Intestinal bacterial translocation is involved in activation of liver macrophages in cirrhotic patients. Macrophages play a key role in liver inflammation and are involved in the pathogenesis of cirrhosis and complications. Bacterial translocation may be determined by presence of bacterial DNA and macrophage activation, by the soluble mannose receptor. We hypothesize that the soluble mannose receptor is released from hepatic macrophages in cirrhosis and associated with bacterial DNA, portal pressure and complications.

METHODS

We investigated 28 cirrhotic patients set for transjugular intrahepatic portosystemic shunt insertion as a result of refractory ascites (n=17), acute (n=3), or recurrent variceal bleeding (n=8). We analysed plasma from the portal and hepatic veins for bacterial DNA and soluble mannose receptor with qPCR and ELISA.

RESULTS

The median soluble mannose receptor level was elevated in the hepatic vein compared with the portal vein (0.57(interquartile range 0.31) vs 0.55(0.40) mg/L, P=.005). The soluble mannose receptor levels were similar in bacterial DNA-positive and -negative patients. The soluble mannose receptor level in the portal and hepatic veins correlated with the portal pressure prior to transjugular intrahepatic portosystemic shunt insertion (r=.52, P<.008, both) and the levels correlated with Child-Pugh score (r=.63 and r=.56, P<.004, both). We observed higher soluble mannose receptor levels in patients with acute variceal bleeding compared to other indications (P<.05).

CONCLUSION

This study showed hepatic soluble mannose receptor excretion with a higher level in the hepatic than the portal vein, though with no associations to bacterial DNA. We observed associations between soluble mannose receptor levels and portal pressure and higher levels in patients with acute variceal bleeding indicating the soluble mannose receptor as a marker of complications of cirrhosis, but not bacterial translocation.

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.

Infection as a Trigger for Portal Hypertension

BACKGROUND

Microbial infections are a relevant problem for patients with liver cirrhosis. Different types of bacteria are responsible for different kinds of infections: Escherichia coli and Klebsiella pneumoniae are frequently observed in spontaneous bacterial peritonitis or urinary tract infections, and Streptococcus pneumoniae and Mycoplasma pneumoniae in pulmonary infections. Mortality is up to 4-fold higher in infected patients with liver cirrhosis than in patients without infections. Key Messages: Infections in patients with liver cirrhosis are due to three major reasons: bacterial translocation, immune deficiency and an increased incidence of systemic infections. Nonparenchymal liver cells like Kupffer cells, sinusoidal endothelial cells and hepatic stellate cells are the first liver cells to come into contact with microbial products when systemic infection or bacterial translocation occurs. Kupffer cell (KC) activation by Toll-like receptor (TLR) agonists and endothelial sinusoidal dysfunction have been shown to be important mechanisms increasing portal pressure following intraperitoneal lipopolysaccharide pretreatment in cirrhotic rat livers. Reduced intrahepatic vasodilation and increased intrahepatic vasoconstriction are the relevant pathophysiological pathways. Thromboxane A2 and leukotriene (LT) C4/D4 have been identified as important vasoconstrictors. Accordingly, treatment with montelukast to inhibit the cysteinyl-LT1 receptor reduced portal pressure in cirrhotic rat livers. Clinical studies have demonstrated that activation of KCs, estimated by the amount of soluble CD163 in the blood, correlates with the risk for variceal bleeding. Additionally, intestinal decontamination with rifaximin in patients with alcohol-associated liver cirrhosis reduced the portal pressure and the risk for variceal bleeding.

CONCLUSIONS

TLR activation of nonparenchymal liver cells by pathogens results in portal hypertension. This might explain the pathophysiologic correlation between microbial infections and portal hypertension in patients with liver cirrhosis. These findings are the basis for both better risk stratifying and new treatment options, such as specific inhibition of TLR for patients with liver cirrhosis and portal hypertension.

Extrahepatic complications to cirrhosis and portal hypertension: Haemodynamic and homeostatic aspects

In addition to complications relating to the liver, patients with cirrhosis and portal hypertension develop extrahepatic functional disturbances of multiple organ systems. This can be considered a multiple organ failure that involves the heart, lungs, kidneys, the immune systems, and other organ systems. Progressive fibrosis of the liver and subsequent metabolic impairment leads to a systemic and splanchnic arteriolar vasodilatation. This affects both the haemodynamic and functional homeostasis of many organs and largely determines the course of the disease. With the progression of the disease, the circulation becomes hyperdynamic with cardiac, pulmonary as well as renal consequences for dysfunction and reduced survival. Infections and a changed cardiac function known as cirrhotic cardiomyopathy may be involved in further aggravation of other complications such as renal failure precipitating the hepatorenal syndrome. Patients with end-stage liver disease and related complications as for example the hepatopulmonary syndrome can only radically be treated by liver transplantation. As a bridge to this treatment, knowledge on the mechanisms of the pathophysiology of complications is essential for the choice of vasoactive drugs, antibiotics, drugs with specific effects on fibrogenesis and inflammation, and drugs that target specific receptors.