Alterations in the gut microbiome after transjugular intrahepatic portosystemic shunt in patients with hepatitis B virus-related portal hypertension.

BACKGROUND: Gut microbiota (GM) affects the progression and response to treatment in liver diseases. The GM composition is diverse and associated with different etiologies of liver diseases. Notably, alterations in GM alterations are observed in patients with portal hypertension (PH) secondary to cirrhosis, with hepatitis B virus (HBV) infection being a major cause of cirrhosis in China. Thus, understanding the role of GM alterations in patients with HBV infection-related PH is essential. AIM: To evaluate GM alterations in patients with HBV-related PH after transjugular intrahepatic portosystemic shunt (TIPS) placement. METHODS: This was a prospective, observational clinical study. There were 30 patients (with a 100% technical success rate) recruited in the present study. Patients with esophagogastric variceal bleeding due to HBV infection-associated PH who underwent TIPS were enrolled. Stool samples were obtained before and one month after TIPS treatment, and GM was analyzed using 16S ribosomal RNA amplicon sequencing. RESULTS: One month after TIPS placement, 8 patients developed hepatic encephalopathy (HE) and were assigned to the HE group; the other 22 patients were assigned to the non-HE group. There was no substantial disparity in the abundance of GM at the phylum level between the two groups, regardless of TIPS treatment (all, P > 0.05). However, following TIPS placement, the following results were observed: (1) The abundance of Haemophilus and Eggerthella increased, whereas that of Anaerostipes, Dialister, Butyricicoccus, and Oscillospira declined in the HE group; (2) The richness of Eggerthella, Streptococcus, and Bilophila increased, whereas that of Roseburia and Ruminococcus decreased in the non-HE group; and (3) Members from the pathogenic genus Morganella appeared in the HE group but not in the non-HE group. CONCLUSION: Intestinal microbiota-related synergism may predict the risk of HE following TIPS placement in patients with HBV-related PH. Prophylactic microbiome therapies may be useful for preventing and treating HE after TIPS placement.

Gut microbiota and metabolites of cirrhotic portal hypertension: a novel target on the therapeutic regulation.

BACKGROUND: The regulatory role of gut microbiota and gut-derived metabolites through the gut-liver axis in the development of cirrhotic portal hypertension (PH) has received increasing attention. METHODS: The review summarized a series of investigations on effects of metabolites derived from microbiota and medicines targeting microbiome including rifaximin, VSL#3, statins, propranolol, FXR agonists as well as drugs derived from bile acids (BAs) on PH progression. RESULTS: Patients with PH exhibit alterations in gut microbial richness and differential overall microbiota community, and several results clearly displayed the correlation of PH with enrichment of Veillonella dispar or depletion of Clostridiales, Peptostreptococcaceae, Alistipes putredinis, Roseburia faecis and Clostridium cluster IV. The gut-derived metabolites including hydrogen sulfide, tryptophan metabolites, butyric acid, secondary BAs and phenylacetic acid (PAA) participate in a range of pathophysiology process of PH through modulating intrahepatic vascular resistance and portal blood flow associated with the formation and progression of PH. Established and emerging drugs targeting on bacterial translocation and intestinal eubiosis are gradually identified as potential strategies for treatments of liver cirrhosis and PH by modulating intestinal inflammation, splanchnic arterial vasodilation and endothelial dysfunction. CONCLUSIONS: Future explorations should further characterize the alteration of the fecal microbiome and metabolite profiles in PH and elucidate the regulatory mechanism of the intestinal microbiome, gut-derived metabolites and gut microbiota targeted pharmaceutical treatments involved in PH.

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.

Microbiota transplants from feces or gut content attenuated portal hypertension and portosystemic collaterals in cirrhotic rats.

Liver cirrhosis and portal hypertension is the end of chronic liver injury with hepatic, splanchnic and portosystemic collateral systems dysregulation. Liver injury is accompanied by gut dysbiosis whereas dysbiosis induces liver fibrosis, splanchnic angiogenesis and dysregulated vascular tones vice versa, making portal hypertension aggravated. It has been proved that intestinal microbiota transplantation alleviates dysbiosis. Nevertheless, the influences of microbiota transplantation on cirrhosis-related portal hypertension are not so clear. Liver cirrhosis with portal hypertension was induced by bile duct ligation (BDL) in rats. Sham rats were surgical controls. Rats randomly received vehicle, fecal or gut (terminal ileum) material transplantation. The results showed that microbiota transplantation from feces or gut material significantly reduced portal pressure in cirrhotic rats (P=0.010, 0.044). Hepatic resistance, vascular contractility, fibrosis and relevant protein expressions were not significantly different among cirrhotic rats. However, microbiota transplantation ameliorated splanchnic hyperdynamic flow and vasodilatation. Mesenteric angiogenesis, defined by whole mesenteric window vascular density, decreased in both transplantation groups and phosphorylated endothelial nitric-oxide synthase (eNOS) was down-regulated. Portosystemic shunts determined by splenorenal shunt (SRS) flow decreased in both transplantation groups (P=0.037, 0.032). Shunting severity assessed by microsphere distribution method showed consistent results. Compared with sham rats, cirrhotic rats lacked Lachnospiraceae. Both microbiota transplants increased Bifidobacterium. In conclusion, microbiota transplantation in cirrhotic rats reduced portal pressure, alleviated splanchnic hyperdynamic circulation and portosystemic shunts. The main beneficial effects may be focused on portosystemic collaterals-related events, such as hepatic encephalopathy and gastroesophageal variceal hemorrhage. Further clinical investigations are mandatory.

Exploratory Research on the Relationship between Human Gut Microbiota and Portal Hypertension.

Objective The relationship between gut microbiota and portal hypertension remains unclear. We investigated the characteristics of the gut microbiota in portal hypertension patients with esophago-gastric varices and liver cirrhosis. Methods Thirty-six patients (12 patients with portal hypertension, 12 healthy controls, and 12 non-cirrhosis patients) were enrolled in this university hospital study. Intestinal bacteria and statistical analyses were performed up to the genus level using the terminal restriction fragment length polymorphism method targeting 16S ribosomal RNA genes, with diversified regions characterizing each bacterium. Results Levels of Lactobacillales were significantly higher (p=0.045) and those of Clostridium cluster IV significantly lower (p=0.014) in patients with portal hypertension than in other patients. This Clostridium cluster contains many butanoic acid-producing strains, including Ruminococcace and Faecalibacterium prausnitzii. Clostridium cluster IX levels were also significantly lower (p=0.045) in portal hypertension patients than in other patients. There are many strains of Clostridium that produce propionic acid, and the effects on the host and the function of these bacterial species in the human intestine remain unknown. Regarding the Bifidobacterium genus, which is supposed to decrease as a result of cirrhosis, no significant decrease was observed in this study. Conclusion In the present study, we provided information on the characteristics of the gut microbiota of portal hypertension patients with esophago-gastric varices due to liver cirrhosis. In the future, we aim to develop probiotic treatments following further analyses that include the species level, such as the intestinal flora analysis method and next-generation sequencers.

Paneth cells promote angiogenesis and regulate portal hypertension in response to microbial signals.

BACKGROUND & AIMS: Paneth cells (PCs) synthesize and secrete antimicrobial peptides that are key mediators of host-microbe interactions, establishing a balance between intestinal microflora and enteric pathogens. We observed that their number increases in experimental portal hypertension and aimed to investigate the mechanisms by which these cells can contribute to the regulation of portal pressure. METHODS: We first treated Math1Lox/LoxVilcreERT2 mice with tamoxifen to induce the complete depletion of intestinal PCs. Subsequently, we performed partial portal vein or bile duct ligation. We then studied the effects of these interventions on hemodynamic parameters, proliferation of blood vessels and the expression of genes regulating angiogenesis. Intestinal organoids were cultured and exposed to different microbial products to study the composition of their secreted products (by proteomics) and their effects on the proliferation and tube formation of endothelial cells (ECs). In vivo confocal laser endomicroscopy was used to confirm the findings on blood vessel proliferation. RESULTS: Portal hypertension was significantly attenuated in PC-depleted mice compared to control mice and was associated with a decrease in portosystemic shunts. Depletion of PCs also resulted in a significantly decreased density of blood vessels in the intestinal wall and mesentery. Furthermore, we observed reduced expression of intestinal genes regulating angiogenesis in Paneth cell depleted mice using arrays and next generation sequencing. Tube formation and wound healing responses were significantly decreased in ECs treated with conditioned media from PC-depleted intestinal organoids exposed to intestinal microbiota-derived products. Proteomic analysis of conditioned media in the presence of PCs revealed an increase in factors regulating angiogenesis and additional metabolic processes. In vivo endomicroscopy showed decreased vascular proliferation in the absence of PCs. CONCLUSIONS: These results suggest that in response to intestinal flora and microbiota-derived factors, PCs secrete not only antimicrobial peptides, but also pro-angiogenic signaling molecules, thereby promoting intestinal and mesenteric angiogenesis and regulating portal hypertension. LAY SUMMARY: Paneth cells are present in the lining of the small intestine. They prevent the passage of bacteria from the intestine into the blood circulation by secreting substances to fight bacteria. In this paper, we discovered that these substances not only act against bacteria, but also increase the quantity of blood vessels in the intestine and blood pressure in the portal vein. This is important, because high blood pressure in the portal vein may result in several complications which could be targeted with novel approaches.

Microbial Profiles of Cirrhosis in the Human Small Intestine.

PURPOSE OF REVIEW: The aim of this review is to summarize the recent literature on associations of small intestinal microbial and bile acid profiles with liver cirrhosis and its complications. RECENT FINDINGS: Recent studies into the duodenal microbiome of patients with cirrhosis have linked the microbiome to certain etiologies of chronic liver disease as well as complications of cirrhosis. In particular, microbial differences in the duodenum of patients with cirrhosis have been linked to the presence of hepatic encephalopathy and varices. While the fecal microbiome of patients with liver cirrhosis is well characterized, the small intestinal microbiome of cirrhotic patients is an active area of research. This review focuses on the current understanding of the small intestinal microbiome in human cirrhosis as well as future directions of the field.

Attenuated fibrosis in specific pathogen-free microbiota in experimental cholestasis- and toxin-induced liver injury.

In advanced chronic liver disease (CLD), the translocation of intestinal bacteria and the resultant increase of proinflammatory cytokines in the splanchnic and systemic circulation may contribute to the progression of fibrosis. We therefore speculated that fibrosis and portal hypertension (PHT) would be attenuated in a mouse model of limited intestinal colonization with altered Schaedler flora (ASF) compared to a more complex colonization with specific pathogen-free (SPF) flora. We induced liver fibrosis in ASF and SPF mice by common bile duct ligation (BDL) or by carbon tetrachloride (CCl4) treatment. We then measured portal pressure (PP), portosystemic shunts (PSSs), and harvested tissues for further analyses. There were no differences in PP between sham-treated ASF or SPF mice. After BDL or CCl4 treatment, PP, PSSs, and hepatic collagen deposition increased in both groups. However, the increase in PP and the degree of fibrosis was significantly higher in ASF than SPF mice. Expression of fibrotic markers α-smooth muscle actin, desmin, and platelet-derived growth factor receptor ß were significantly higher in ASF than SPF mice. This was associated with higher activation of hepatic immune cells (macrophages, neutrophils) and decreased expression of the intestinal epithelial tight junction proteins (claudin-1, occludin-1). In 2 models of advanced CLD, SPF mice presented significantly attenuated liver injury, fibrosis, and PHT compared to ASF mice. In contrast to our hypothesis, these findings suggest that a complex intestinal microbiota may play a "hepato-protective" role.-Moghadamrad, S., Hassan, M., McCoy, K. D., Kirundi, J., Kellmann, P., De Gottardi, A. Attenuated fibrosis in specific pathogen-free microbiota in experimental cholestasis- and toxin-induced liver injury.

Von Willebrand factor indicates bacterial translocation, inflammation, and procoagulant imbalance and predicts complications independently of portal hypertension severity.

BACKGROUND: Elevated plasma von Willebrand factor antigen (vWF) has been shown to indicate the presence of clinically significant portal hypertension, and thus, predicts the development of clinical events in patients with cirrhosis. AIM: To investigate the impact of bacterial translocation and inflammation on vWF, as well as the association between vWF and procoagulant imbalance. Moreover, we assessed whether vWF predicts complications of cirrhosis, independent of the severity of portal hypertension. METHODS: Our study population comprised 225 patients with hepatic venous pressure gradient (HVPG) ≥ 10 mm Hg without active bacterial infections or hepatocellular carcinoma. RESULTS: vWF correlated with markers of bacterial translocation (lipopolysaccharide-binding protein [LBP; ρ = 0.201; P = 0.021]), inflammation (interleukin 6 [IL-6; ρ = 0.426; P < 0.001] and C-reactive protein [CRP; ρ = 0.249; P < 0.001]), and procoagulant imbalance (factor VIII/protein C ratio; ρ = 0.507; P < 0.001). Importantly, the associations between vWF and these parameters were independent of HVPG. Moreover, vWF (per 10%) independently predicted variceal bleeding (hazard ratio [HR]: 1.08 [95% confidence interval (95% CI): 1.01-1.16]; P = 0.023), requirement of paracentesis (HR: 1.05 [95% CI: 1.01-1.1]; P = 0.023) and bacterial infections (HR: 1.04 [95% CI: 1-1.09]; P = 0.04) including spontaneous bacterial peritonitis (HR: 1.09 [95% CI: 0.999-1.18]; P = 0.053) on a trend-wise level. After backward elimination, vWF (HR: 1.05 [95% CI: 1.02-1.08]; P = 0.003) and CRP (per 10 mg/L; HR: 1.53 [95% CI: 1.14-2.05]; P = 0.005) remained in the final model for transplant-free mortality. Finally, the independent prognostic value of vWF/CRP groups for mortality was confirmed by competing risk analysis. CONCLUSION: Our results demonstrate that vWF is not only a marker of portal hypertension but also independently linked to bacterial translocation, inflammation and procoagulant imbalance, which might explain its HVPG-independent association with most clinical events. Prognostic groups based on vWF/CRP efficiently discriminate between patients with a poor 5-year survival and patients with a favourable prognosis.

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

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

Restoration of a healthy intestinal microbiota normalizes portal hypertension in a rat model of nonalcoholic steatohepatitis.

Portal hypertension (PH) drives most of the clinical complications in chronic liver diseases. However, its progression in nonalcoholic steatohepatitis (NASH) and its association with the intestinal microbiota (IM) have been scarcely studied. Our aim was to investigate the role of the IM in the mechanisms leading to PH in early NASH. The experimental design was divided in two stages. In stage 1, Sprague-Dawley rats were fed for 8 weeks a high-fat, high-glucose/fructose diet (HFGFD) or a control diet/water (CD). Representative rats were selected as IM donors for stage 2. In stage 2, additional HFGFD and CD rats underwent intestinal decontamination, followed by IM transplantation with feces from opposite-diet donors (heterologous transplant) or autologous fecal transplant (as controls), generating four groups: CD-autotransplanted, CD-transplanted, HFGFD-autotransplanted, HFGFD-transplanted. After IM transplantation, the original diet was maintained for 12-14 days until death. HFGFD rats developed obesity, insulin resistance, NASH without fibrosis but with PH, intrahepatic endothelial dysfunction, and IM dysbiosis. In HFGFD rats, transplantation with feces from CD donors caused a significant reduction of PH to levels comparable to CD without significant changes in NASH histology. The reduction in PH was due to a 31% decrease of intrahepatic vascular resistance compared to the HFGFD-autotransplanted group (P < 0.05). This effect occurs through restoration of the sensitivity to insulin of the hepatic protein kinase B-dependent endothelial nitric oxide synthase signaling pathway. CONCLUSION: The IM exerts a direct influence in the development of PH in rats with diet-induced NASH and dysbiosis; PH, insulin resistance, and endothelial dysfunction revert when a healthy IM is restored. (Hepatology 2018;67:1485-1498).

Infections in patients affected by liver cirrhosis: an update.

Patients with liver cirrhosis present an increased incidence of infections. The main cause has been founded in alterations of the enteric flora and of the intestinal barrier probably due to portal hypertension, in addition to a reticulo-endothelial system dysfunction. Furthermore, those living with cirrhosis can report a high predisposition to sepsis and septic shock, due to the excessive response of pro-inflammatory cytokines and a complessive hemodynamic derangement. By the analysis in the experimental model of the cirrhotic rat, it was demonstrated that radio-labelled Escherichia coli given by the oral route resulted in the location of the bacteria in the gut, the ascitic fluid and mesenteric lymph nodes, a phenomenon known as bacterial translocation. Bacteria encountered with the highest frequency are those colonizing the intestinal tract, such as E. coli, Klebsiella pneumoniae and Enterobacteriaceae, intracellular bacteria and parasites are reported with a lower frequency. Multi-drug resistant bacteria are cultured with the highest frequency in those with frequent hospitalisations and report both high septic shock and mortality rates. Spontaneous bacterial peritonitis (SBP) is the commonest infection in cirrhotic, estimated to occur in 10-30% of the cases with ascites. A practical approach may include administration of a protected penicillin, III generation cephalosporin or quinolones in uncomplicated cases. Instead, in complicated cases and in nosocomial SBP, administration of cephalosporin or quinolones can be burned by the high resistance rate and drugs active against ESBL-producing bacteria and multi-drug resistant Gram positive bacteria have to be considered as empiric therapy, until cultures are available. When cultures are not readily available and patients fail to improve a repeated diagnostic paracentesis should be performed. Current investigations suggest that norfloxacin 400 mg/day orally has been reported to successfully prevent SBP in patients with low-protein ascites and patients with prior SBP.

Microbiome and bacterial translocation in cirrhosis. / Microbioma y traslocación bacteriana en la cirrosis.

Qualitative and quantitative changes in gut microbiota play a very important role in cirrhosis. Humans harbour around 100 quintillion gut bacteria, thus representing around 10 times more microbial cells than eukaryotic ones. The gastrointestinal tract is the largest surface area in the body and it is subject to constant exposure to these living microorganisms. The existing symbiosis, proven by the lack of proinflammatory response against commensal bacteria, implies the presence of clearly defined communication lines that contribute to the maintenance of homeostasis of the host. Therefore, alterations of gut flora seem to play a role in the pathogenesis and progress of multiple liver and gastrointestinal diseases. This has made its selective modification into an area of high therapeutic interest. Bacterial translocation is defined as the migration of bacteria or bacterial products from the intestines to the mesenteric lymph nodes. It follows that alteration in gut microbiota have shown importance, at least to some extent, in the pathogenesis of several complications arising from terminal liver disease, such as hepatic encephalopathy, portal hypertension and spontaneous bacterial peritonitis. This review sums up, firstly, how liver disease can alter the common composition of gut microbiota, and secondly, how this alteration contributes to the development of complications in cirrhosis.

Early invasive fungal infections and colonization in patients with cirrhosis admitted to the intensive care unit.

Bacterial infections in cirrhosis are common and associated with increased mortality, but little is known about fungal infections. The aim of this study, a sub-analysis of the Fungal Infection Risk Evaluation study, was to assess the incidence and implications of early invasive fungal disease (IFD) in patients with cirrhosis admitted to intensive care units (ICU). Clinical and laboratory parameters collected in the first 3 days of ICU stay for 782 patients with cirrhosis and/or portal hypertension were analysed and compared with those of 273 patients with very severe cardiovascular disease (CVD). The CVD patients had more co-morbidities and higher APACHE II scores. The overall incidence of IFD was similar in the two groups, but the incidence of IFD in ICU was higher in liver patients (1% versus 0.4%; p 0.025) as was fungal colonization (23.8% versus 13.9%; p 0.001). The ICU and in-hospital mortality, and length of stay were similar in the two groups. A higher proportion of liver patients received antifungal therapy (19.2% versus 7%; p <0.0005). There was no difference in mortality between colonized patients who received antifungal therapy and colonized patients who did not. The incidence of IFD in patients with cirrhosis in ICU is higher compared with another high-risk group, although it is still very low. This risk might be higher in patients with advanced liver disease admitted with acute-on-chronic liver failure, and this should be investigated further. Our data do not support prophylactic use of antifungal therapy in cirrhosis.

Probiotics in Nonalcoholic Fatty Liver Disease, Nonalcoholic Steatohepatitis, and Cirrhosis.

With the growing epidemic of obesity, the incidence of both nonalcoholic fatty liver disease (NAFL) and nonalcoholic steatohepatitis (NASH) is increasing. The intestinal microbiota differs between individuals who are obese or have normal body mass indices. Animal studies have shown increased intestinal permeability in NAFL, NASH, and cirrhosis. This increases the risk of oxidative and inflammatory injury to the liver from intestinal microbacteria. It may also increase the risk of fatty acid injury and fatty deposition. Bacterial translocation is associated with increased portal hypertension and hepatic encephalopathy in cirrhosis. By preventing bacterial adhesion and translocation, probiotics may have a role in the management of patients with NAFL, NASH, and cirrhosis. Multiple small studies have suggested that probiotics improve some of the clinical markers of activity in patients with NAFL and NASH. Controlled studies have also shown improved outcomes in patients with cirrhosis who were treated with probiotics.

IGF-1 decreases portal vein endotoxin via regulating intestinal tight junctions and plays a role in attenuating portal hypertension of cirrhotic rats.

BACKGROUND: Intestinal barrier dysfunction is not only the consequence of liver cirrhosis, but also an active participant in the development of liver cirrhosis. Previous studies showed that external administration of insulin-like growth factor 1 (IGF-1) improved intestinal barrier function in liver cirrhosis. However, the mechanism of IGF-1 on intestinal barrier in liver cirrhosis is not fully elucidated. The present study aims to investigate the mechanisms of IGF-1 improving intestinal barrier function via regulating tight junctions in intestines. METHODS: We used carbon tetrachloride induced liver cirrhotic rats to investigate the effect of IGF-1 on intestinal claudin-1 and occludin expressions, serum alanine transaminase (ALT) and aspartate transaminase (AST) levels, severity of liver fibrosis, portal pressures, enterocytic apoptosis and lipopolysaccharides (LPS) levels in portal vein. The changes of IGF-1 in serum during the development of rat liver cirrhosis were also evaluated. Additionally, we assessed the effect of IGF-1 on claudin-1 and occludin expressions, changes of transepithelial electrical resistance (TEER) and apoptosis in Caco-2 cells to confirm in vivo findings. RESULTS: Serum IGF-1 levels were decreased in the development of rat liver cirrhosis, and external administration of IGF-1 restored serum IGF-1 levels. External administration of IGF-1 reduced serum ALT and AST levels, severity of liver fibrosis, LPS levels in portal vein, enterocytic apoptosis and portal pressure in cirrhotic rats. External administration of IGF-1 increased the expressions of claudin-1 and occludin in enterocytes, and attenuated tight junction dysfunction in intestines of cirrhotic rats. LPS decreased TEER in Caco-2 cell monolayer. LPS also decreased claudin-1 and occludin expressions and increased apoptosis in Caco-2 cells. Furthermore, IGF-1 attenuated the effect of LPS on TEER, claudin-1 expression, occludin expression and apoptosis in Caco-2 cells. CONCLUSIONS: Tight junction dysfunction develops during the development of liver cirrhosis, and endotoxemia will develop subsequently. Correspondingly, increased endotoxin in portal system worsens tight junction dysfunction via decreasing intestinal occludin and claudin-1 expressions and increasing enterocytic apoptosis. Endotoxemia and intestinal barrier dysfunction form a vicious circle. External administration of IGF-1 breaks this vicious circle. Improvement of tight junctions might be one possible mechanism of the restoration of intestinal barrier function mediated by IGF-1.

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.

Attenuated portal hypertension in germ-free mice: Function of bacterial flora on the development of mesenteric lymphatic and blood vessels.

UNLABELLED: Intestinal bacterial flora may induce splanchnic hemodynamic and histological alterations that are associated with portal hypertension (PH). We hypothesized that experimental PH would be attenuated in the complete absence of intestinal bacteria. We induced prehepatic PH by partial portal vein ligation (PPVL) in germ-free (GF) or mice colonized with altered Schaedler's flora (ASF). After 2 or 7 days, we performed hemodynamic measurements, including portal pressure (PP) and portosystemic shunts (PSS), and collected tissues for histomorphology, microbiology, and gene expression studies. Mice colonized with intestinal microbiota presented significantly higher PP levels after PPVL, compared to GF, mice. Presence of bacterial flora was also associated with significantly increased PSS and spleen weight. However, there were no hemodynamic differences between sham-operated mice in the presence or absence of intestinal flora. Bacterial translocation to the spleen was demonstrated 2 days, but not 7 days, after PPVL. Intestinal lymphatic and blood vessels were more abundant in colonized and in portal hypertensive mice, as compared to GF and sham-operated mice. Expression of the intestinal antimicrobial peptide, angiogenin-4, was suppressed in GF mice, but increased significantly after PPVL, whereas other angiogenic factors remained unchanged. Moreover, colonization of GF mice with ASF 2 days after PPVL led to a significant increase in intestinal blood vessels, compared to controls. The relative increase in PP after PPVL in ASF and specific pathogen-free mice was not significantly different. CONCLUSION: In the complete absence of gut microbial flora PP is normal, but experimental PH is significantly attenuated. Intestinal mucosal lymphatic and blood vessels induced by bacterial colonization may contribute to development of PH.

Gut microbiota-related complications in cirrhosis.

Gut microbiota plays an important role in cirrhosis. The liver is constantly challenged with commensal bacteria and their products arriving through the portal vein in the so-called gut-liver axis. Bacterial translocation from the intestinal lumen through the intestinal wall and to mesenteric lymph nodes is facilitated by intestinal bacterial overgrowth, impairment in the permeability of the intestinal mucosal barrier, and deficiencies in local host immune defences. Deranged clearance of endogenous bacteria from portal and systemic circulation turns the gut into the major source of bacterial-related complications. Liver function may therefore be affected by alterations in the composition of the intestinal microbiota and a role for commensal flora has been evidenced in the pathogenesis of several complications arising in end-stage liver disease such as hepatic encephalopathy, splanchnic arterial vasodilatation and spontaneous bacterial peritonitis. The use of antibiotics is the main therapeutic pipeline in the management of these bacteria-related complications. However, other strategies aimed at preserving intestinal homeostasis through the use of pre-, pro- or symbiotic formulations are being studied in the last years. In this review, the role of intestinal microbiota in the development of the most frequent complications arising in cirrhosis and the different clinical and experimental studies conducted to prevent or improve these complications by modifying the gut microbiota composition are summarized.