Effect of rifaximin on gut microbiota composition in advanced liver disease and its complications

Gut microbiome composition in patients with liver cirrhosis with and without hepatic encephalopathy: A systematic review and meta-analysis

BACKGROUND

The gut microbiome is associated with hepatic encephalopathy (HE), but research results on the gut microbiome characteristics of patients with liver cirrhosis with and without HE are inconsistent.

AIM

To study the gut microbiota characteristics of patients with liver cirrhosis with and without HE.

METHODS

We searched the PubMed, Web of Science, EMBASE, and Cochrane databases using two keywords, HE, and gut microbiome. According to the inclusion and exclusion criteria, suitable literature was screened to extract data on the diversity and composition of the fecal microbiota in patients with liver cirrhosis with and without HE. The data were analyzed using RevMan and STATA.

RESULTS

Seventeen studies were included: (1) A meta-analysis of 7 studies revealed that the Shannon index in liver cirrhosis patients with HE was significantly lower than that in patients without HE [-0.20, 95% confidence interval (CI): -0.28 to -0.13, I2 = 20%]; (2) The relative abundances of Lachnospiraceae (-2.73, 95%CI: -4.58 to -0.87, I2 = 38%) and Ruminococcaceae (-2.93, 95%CI: -4.29 to -1.56, I2 = 0%) in liver cirrhosis patients with HE was significantly lower than those in patients without HE; (3) In patients with HE, Enterococcus, Proteobacteria, Enterococcaceae, and Enterobacteriaceae proportions increased, but Ruminococcaceae, Lachnospiraceae, Prevotellaceae, and Bacteroidetes proportions decreased; (4) Differences in the fecal metabolome between liver cirrhosis patients with and without HE were detected; and (5) Differential gut microbiomes may serve as diagnostic and prognostic tools.

CONCLUSION

The gut microbiomes of patients with liver cirrhosis with and without HE differ. Some gut microbiomes may distinguish liver cirrhosis patients with or without HE and determine patient prognosis.

Early treatment with rifaximin during epileptogenesis reverses gut alterations and reduces seizure duration in a mouse model of acquired epilepsy

The gut microbiota is altered in epilepsy and is emerging as a potential target for new therapies. We studied the effects of rifaximin, a gastrointestinal tract-specific antibiotic, on seizures and neuropathology and on alterations in the gut and its microbiota in a mouse model of temporal lobe epilepsy (TLE). Epilepsy was induced by intra-amygdala kainate injection causing status epilepticus (SE) in C57Bl6 adult male mice. Sham mice were injected with vehicle. Two cohorts of SE mice were fed a rifaximin-supplemented diet for 21 days, starting either at 24 h post-SE (early disease stage) or at day 51 post-SE (chronic disease stage). Corresponding groups of SE mice (one each disease stage) were fed a standard (control) diet. Cortical ECoG recording was done at each disease stage (24/7) for 21 days in all SE mice to measure the number and duration of spontaneous seizures during either rifaximin treatment or control diet. Then, epileptic mice ± rifaximin and respective sham mice were sacrificed and brain, gut and feces collected. Biospecimens were used for: (i) quantitative histological analysis of the gut structural and cellular components; (ii) markers of gut inflammation and intestinal barrier integrity by RTqPCR; (iii) 16S rRNA metagenomics analysis in feces. Hippocampal neuronal cell loss was assessed in epileptic mice killed in the early disease phase. Rifaximin administered for 21 days post-SE (early disease stage) reduced seizure duration (p < 0.01) and prevented hilar mossy cells loss in the hippocampus compared to epileptic mice fed a control diet. Epileptic mice fed a control diet showed a reduction of both villus height and villus height/crypt depth ratio (p < 0.01) and a decreased number of goblet cells (p < 0.01) in the duodenum, as well as increased macrophage (Iba1)-immunostaining in the jejunum (p < 0.05), compared to respective sham mice. Rifaximin's effect on seizures was associated with a reversal of gut structural and cellular changes, except for goblet cells which remained reduced. Seizure duration in epileptic mice was negatively correlated with the number of mossy cells (p < 0.01) and with villus height/crypt depth ratio (p < 0.05). Rifaximin-treated epileptic mice also showed increased tight junctions (occludin and ZO-1, p < 0.01) and decreased TNF mRNA expression (p < 0.01) in the duodenum compared to epileptic mice fed a control diet. Rifaximin administered for 21 days in chronic epileptic mice (chronic disease stage) did not change the number or duration of seizures compared to epileptic mice fed a control diet. Chronic epileptic mice fed a control diet showed an increased crypt depth (p < 0.05) and reduced villus height/crypt depth ratio (p < 0.01) compared to respective sham mice. Rifaximin treatment did not affect these intestinal changes. At both disease stages, rifaximin modified α- and β-diversity in epileptic and sham mice compared to respective mice fed a control diet. The microbiota composition in epileptic mice, as well as the effects of rifaximin at the phylum, family and genus levels, depended on the stage of the disease. During the early disease phase, the abundance of specific taxa was positively correlated with seizure duration in epileptic mice. In conclusion, gut-related alterations reflecting a dysfunctional state, occur during epilepsy development in a TLE mouse model. A short-term treatment with rifaximin during the early phase of the disease, reduced seizure duration and neuropathology, and reversed some intestinal changes, strengthening the therapeutic effects of gut-based therapies in epilepsy.

Rifaximin Ameliorates Loperamide-Induced Constipation in Rats through the Regulation of Gut Microbiota and Serum Metabolites

Structural changes in the gut microbiota are closely related to the development of functional constipation, and regulating the gut microbiota can improve constipation. Rifaximin is a poorly absorbed antibiotic beneficial for regulating gut microbiota, but few studies have reported its effects on constipation. The purpose of this study was to investigate the effect of rifaximin on loperamide-induced constipation in SD rats. The results showed that rifaximin improved constipation by increasing serum 5-HT, SP, and the mRNA expression of AQP3, AQP8, and reducing the mRNA expression of TLR2 and TLR4. In addition, rifaximin could regulate the gut microbiota of constipated rats, such as increasing the potentially beneficial bacteria Akkermansia muciniphila and Lactobacillus murinus, reducing the Bifidobacterium pseudolongum. According to metabolomics analysis, many serum metabolites, including bile acids and steroids, were changed in constipated rats and were recovered via rifaximin intervention. In conclusion, rifaximin might improve loperamide-induced constipation in rats by increasing serum excitatory neurotransmitters and neuropeptides, modulating water metabolism, and facilitating intestinal inflammation. Muti-Omics analysis results showed that rifaximin has beneficial regulatory effects on the gut microbiota and serum metabolites in constipated rats, which might play critical roles in alleviating constipation. This study suggests that rifaximin might be a potential strategy for treating constipation.

Principles of minimize bleeding and the transfusion of blood and its components in operated patients - surgical aspects

One of the target of perioperative tratment in surgery is decreasing intraoperative bleeding, which increases the number of perioperative procedures, mortality and treatment costs, and also causes the risk of transfusion of blood and its components. Trying to minimize the blood loss(mainly during the operation) as well as the need to transfuse blood and its components (broadly understood perioperative period) should be standard treatment for a patient undergoing a procedure. In the case of this method, the following steps should be taken: 1) in the preoperative period: identyfication of risk groups as quickly as possible, detecting and treating anemia, applying prehabilitation, modyfying anticoagulant treatment, considering donating one's own blood in some patients and in selected cases erythropoietin preparations; 2) in the perioperative period: aim for normothermia, normovolemia and normoglycemia, use of surgical methods that reduce bleeding, such as minimally invasive surgery, high-energy coagulation, local hemostatics, prevention of surgical site infection, proper transfusion of blood and its components if it occurs; 3) in the postoperative period: monitor the condition of patients, primarily for the detection of bleeding, rapid reoperation if required, suplementation (oral administration preferred) nutrition with microelements (iron) and vitamins, updating its general condition. All these activities, comprehensively and in surgical cooperation with the anesthesiologist, should reduce the blood loss and transfusion of blood and its components.

Gut Microbiota and Neuroinflammation in Acute Liver Failure and Chronic Liver Disease

Acute liver failure and chronic liver disease are associated with a wide spectrum of neurological changes, of which the best known is hepatic encephalopathy (HE). Historically, hyperammonemia, causing astrocyte swelling and cerebral oedema, was considered the main etiological factor in the pathogenesis of cerebral dysfunction in patients with acute and/or chronic liver disease. However, recent studies demonstrated a key role of neuroinflammation in the development of neurological complications in this setting. Neuroinflammation is characterized by activation of microglial cells and brain secretion of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, which alter neurotransmission, leading to cognitive and motor dysfunction. Changes in the gut microbiota resulting from liver disease play a crucial role in the pathogenesis of neuroinflammation. Dysbiosis and altered intestinal permeability, resulting in bacterial translocation and endotoxemia, are responsible for systemic inflammation, which can spread to brain tissue and trigger neuroinflammation. In addition, metabolites derived from the gut microbiota can act on the central nervous system and facilitate the development of neurological complications, exacerbating clinical manifestations. Thus, strategies aimed at modulating the gut microbiota may be effective therapeutic weapons. In this review, we summarize the current knowledge on the role of the gut-liver-brain axis in the pathogenesis of neurological dysfunction associated with liver disease, with a particular focus on neuroinflammation. In addition, we highlight emerging therapeutic approaches targeting the gut microbiota and inflammation in this clinical setting.

Efficacy and Safety of Rifaximin in the Prevention of Recurrent Episodes of Hepatic Encephalopathy: A Systematic Review and Meta-analysis

BACKGROUND

Rifaximin is an oral antimicrobial drug with a broad-spectrum effect. It locally regulates the function and structure of intestinal bacteria and decreases intestinal endotoxemia. We aimed to investigate the preventive role of rifaximin in recurrent episodes of hepatic encephalopathy in cases with a history of hepatic diseases.

METHODS

We searched PubMed, Scopus, and Web of Science for the relevant studies using the following search strategy: "(Rifaximin) OR (Xifaxan) AND (cirrhosis) OR (encephalopathy)." We assessed the risk of bias using Cochrane's risk of bias tool. We included the following outcomes: recurrence of hepatic encephalopathy, adverse events, mortality rate, and time to the first episode of hepatic encephalopathy from the time of randomization (days). We performed the analysis of homogeneous data under the fixed-effects model, while analysis of heterogeneous data was performed under the random-effects model.

RESULTS

We analyzed data obtained from 999 patients from 7 included trials. The overall risk ratio proved that the rifaximin group was associated with a lower recurrence rate than the control group (risk ratio [RR] = 0.61[0.50, 0.73], P = .001). We found no significant variation in both groups regarding adverse events (RR = 1.08 [0.89, 1.32], P = .41), and mortality rates (RR = 0.98 [0.61, 1.57], P = .93). The overall risk of bias results was low.

CONCLUSION

The meta-analysis showed that in patients allocated to the rifaximin group, the incidence rate of hepatic encephalopathy was significantly lower when compared with those in the control group with no difference in both groups regarding adverse events and mortality rates.

Future Modulation of Gut Microbiota: From Eubiotics to FMT, Engineered Bacteria, and Phage Therapy

The human gut is inhabited by a multitude of bacteria, yeasts, and viruses. A dynamic balance among these microorganisms is associated with the well-being of the human being, and a large body of evidence supports a role of dysbiosis in the pathogenesis of several diseases. Given the importance of the gut microbiota in the preservation of human health, probiotics, prebiotics, synbiotics, and postbiotics have been classically used as strategies to modulate the gut microbiota and achieve beneficial effects for the host. Nonetheless, several molecules not typically included in these categories have demonstrated a role in restoring the equilibrium among the components of the gut microbiota. Among these, rifaximin, as well as other antimicrobial drugs, such as triclosan, or natural compounds (including evodiamine and polyphenols) have common pleiotropic characteristics. On one hand, they suppress the growth of dangerous bacteria while promoting beneficial bacteria in the gut microbiota. On the other hand, they contribute to the regulation of the immune response in the case of dysbiosis by directly influencing the immune system and epithelial cells or by inducing the gut bacteria to produce immune-modulatory compounds, such as short-chain fatty acids. Fecal microbiota transplantation (FMT) has also been investigated as a procedure to restore the equilibrium of the gut microbiota and has shown benefits in many diseases, including inflammatory bowel disease, chronic liver disorders, and extraintestinal autoimmune conditions. One of the most significant limits of the current techniques used to modulate the gut microbiota is the lack of tools that can precisely modulate specific members of complex microbial communities. Novel approaches, including the use of engineered probiotic bacteria or bacteriophage-based therapy, have recently appeared as promising strategies to provide targeted and tailored therapeutic modulation of the gut microbiota, but their role in clinical practice has yet to be clarified. The aim of this review is to discuss the most recently introduced innovations in the field of therapeutic microbiome modulation.

Gut Microbiota and Infectious Complications in Advanced Chronic Liver Disease: Focus on Spontaneous Bacterial Peritonitis

Liver cirrhosis is a chronic disease that can be complicated by episodes of decompensation such as variceal bleeding, hepatic encephalopathy, ascites, and jaundice, with subsequent increased mortality. Infections are also among the most common complications in cirrhotic patients, mostly due to a defect in immunosurveillance. Among them, one of the most frequent is spontaneous bacterial peritonitis (SBP), defined as the primary infection of ascitic fluid without other abdominal foci. SBP is mainly induced by Gram-negative bacteria living in the intestinal tract, and translocating through the intestinal barrier, which in cirrhotic patients is defective and more permeable. Moreover, in cirrhotic patients, the intestinal microbiota shows an altered composition, poor in beneficial elements and enriched in potentially pathogenic ones. This condition further promotes the development of leaky gut and increases the risk of SBP. The first-line treatment of SBP is antibiotic therapy; however, the antibiotics used have a broad spectrum of action and may adversely affect the composition of the gut microbiota, worsening dysbiosis. For this reason, the future goal is to use new therapeutic agents that act primarily on the gut microbiota, selectively modulating it, or on the intestinal barrier, reducing its permeability. In this review, we aim to describe the reciprocal relationship between gut microbiota and SBP, focusing on pathogenetic aspects but also on new future therapies.

Modulation of duodenal and jejunal microbiota by rifaximin in mice with CCl4-induced liver fibrosis

BACKGROUND

Rifaximin is a poorly absorbed broad-spectrum antibiotic used for hepatic encephalopathy. Although increased Lactobacillaceae and decreased Bacteroidetes abundance are characteristic of hepatic encephalopathy, rifaximin does not dramatically alter the stool microbiota. As the antimicrobial effect of rifaximin increases by micellization with bile acids, we hypothesized that rifaximin alters the microbiota in the duodenum and jejunum, where the levels of bile acids are abundant.

METHODS AND RESULTS

Eight-week-old BALB/c mice were injected with carbon tetrachloride (CCl₄) intraperitoneally for 12 weeks to induce liver fibrosis. The mice were grouped into the control (n = 9), CCl₄ (n = 13), and rifaximin group in which mice were treated with rifaximin for two weeks after CCl₄ administration (n = 13). We analyzed the microbiota of the duodenum, jejunum, ileum, cecum, and stool using 16S ribosomal RNA gene analysis. The content of Lactobacillaceae, the most abundant bacterial family in the duodenum and small intestine, increased in the CCl₄ group, especially in the jejunum (median 67.0% vs 87.8%, p = 0.03). Rifaximin significantly decreased Lactobacillaceae content in the duodenum (median 79.4% vs 19.0%, p = 0.006) and jejunum (median 87.8% vs 61.3%, p = 0.03), but not in the ileum, cecum, and stool. Bacteroidetes abundance tended to decrease on CCl₄ administration and increased following rifaximin treatment in the duodenum and jejunum. S24_7, the most abundant family in Bacteroidetes, demonstrated a significant inverse correlation with Lactobacillaceae (duodenum, r = - 0.61, p < 0.001; jejunum, r = - 0.72, p < 0.001). In the ileum, cecum, and stool, the effect of rifaximin on the microbiota was minimal, with changes within the same phylum. The percentage of bacterial families, such as Lactobacillaceae and S24_7 in the duodenum and small intestine, did not correlate with that in the stool.

CONCLUSIONS

The abundance of Lactobacillaceae increased in the jejunum of mice with CCl₄-induced liver fibrosis, while rifaximin significantly reduced it in the duodenum and jejunum. Thus, rifaximin possibly exerts its effect by altering the duodenal and jejunal microbiota. Furthermore, changes in the duodenal and small intestinal microbiota were not associated with that of stool, suggesting that the analysis of stool microbiota is insufficient to evaluate upper intestinal microbiota.

Rifaximin Improves Liver Functional Reserve by Regulating Systemic Inflammation

Rifaximin, a non-absorbable antibiotic, has been demonstrated to be effective against hepatic encephalopathy (HE); however, its efficacy on liver functional reserve remains unknown. Here, we evaluated the efficacy of rifaximin on the liver functional reserve and serological inflammation-based markers in patients with cirrhosis. A retrospective study was conducted on patients who received rifaximin for more than three months at our hospital between November 2016 and October 2021. The recurrence and grade of HE, serological ammonia levels, Child–Pugh score (CPS), and serological inflammation-based markers such as the neutrophil–lymphocyte ratio (NLR), lymphocyte–monocyte ratio (LMR), platelet–lymphocyte ratio (PLR), C-reactive protein (CRP), and CRP to albumin ratio (CAR) were evaluated. The correlations between serological inflammation-based markers and liver functional reserve were evaluated. HE grades, serum ammonia levels, and inflammation-based markers significantly improved at three months compared with those at baseline. Patients with improved albumin levels showed significantly higher CRP improvement rates at both 3 and 12 months. Patients with an improvement in CAR at 3 months demonstrated a significant improvement in CPS at 12 months. Rifaximin improved the liver functional reserve in patients with cirrhosis. Improvements in inflammation-based markers, particularly CRP and albumin, may be involved in this process.

Influence of Gut–Liver Axis on Portal Hypertension in Advanced Chronic Liver Disease: The Gut Microbiome as a New Protagonist in Therapeutic Management

Clinically significant portal hypertension is associated with most complications of advanced chronic liver disease (ACLD), including variceal bleeding, ascites, spontaneous bacterial peritonitis, hepatorenal syndrome, and hepatic encephalopathy. Gut dysbiosis is a hallmark of ACLD with portal hypertension and consists of the overgrowth of potentially pathogenic bacteria and a decrease in autochthonous bacteria; additionally, congestion makes the intestinal barrier more permeable to bacteria and their products, which contributes to the development of complications through inflammatory mechanisms. This review summarizes current knowledge on the role of the gut–liver axis in the pathogenesis of portal hypertension, with a focus on therapies targeting portal hypertension and the gut microbiota. The modulation of the gut microbiota on several levels represents a major challenge in the upcoming years; in-depth characterization of the molecular and microbiological mechanisms linking the gut–liver axis to portal hypertension in a bidirectional relationship could pave the way to the identification of new therapeutic targets for innovative therapies in the management of ACLD.

Gut microbiota alteration and modulation in hepatitis B virus-related fibrosis and complications: Molecular mechanisms and therapeutic inventions

Hepatitis B virus (HBV) has posed a threat to public health, mainly resulting in liver damage. With long-term accumulation of extracellular matrix, patients with chronic hepatitis B are at high risk of developing into liver fibrosis and cirrhosis and even life-threatening hepatic carcinoma. The occurrence of complications such as spontaneous bacterial peritonitis and hepatic encephalopathy greatly increases disability and mortality. With deeper understanding of the bidirectional interaction between the liver and the gut (gut-liver axis), there is a growing consensus that the human health closely relates to the gut microbiota. Supported by animal and human studies, the gut microbiota alters as the HBV-related liver fibrosis initials and progresses, characterized as the decrease of the ratio between “good” and “potentially pathogenic” microbes. When the primary disease is controlled via antiviral treatment, the gut microbiota dysfunction tends to be improved. Conversely, the recovery of gut microbiota can promote the regression of liver fibrosis. Therapeutic strategies targeted on gut microbiota (rifaximin, probiotics, engineered probiotics and fecal microbiota transplantation) have been applied to animal models and patients, obtaining satisfactory results.

Non-alcoholic fatty liver disease in irritable bowel syndrome: More than a coincidence?

Irritable bowel syndrome (IBS) and non-alcoholic fatty liver disease (NAFLD) are amongst the most common gastrointestinal and liver conditions encountered in primary and secondary care. Recently, there has been interest in the apparent co-incidence of NAFLD in patients with IBS mainly driven by improved understanding of their shared risk factors and pathophysiology. In this paper we summarize the shared risk factors which include; overlapping nutritional and dietary factors as well as shared putative mechanisms of pathophysiology. These include changes in the gut microbiome, gut permeability, immunity, small bowel bacterial overgrowth and bile acid metabolism. This paper describes how these shared risk factors and etiological factors may have practical clinical implications for these highly prevalent conditions. It also highlights some of the limitations of current epidemiological data relating to estimates of the overlapping prevalence of the two conditions which have resulted in inconsistent results and, therefore the need for further research. Early recognition and management of the overlap could potentially have impacts on treatment outcomes, compliance and morbidity of both conditions. Patients with known IBS who have abnormal liver function tests or significant risk factors for NAFLD should be investigated appropriately for this possibility. Similarly, IBS should be considered in patients with NAFLD and symptoms of abdominal pain associated with defecation, an altered bowel habit and bloating.

Human Gut Microbiota in Health and Selected Cancers

The majority of the epithelial surfaces of our body, and the digestive tract, respiratory and urogenital systems, are colonized by a vast number of bacteria, archaea, fungi, protozoans, and viruses. These microbiota, particularly those of the intestines, play an important, beneficial role in digestion, metabolism, and the synthesis of vitamins. Their metabolites stimulate cytokine production by the human host, which are used against potential pathogens. The composition of the microbiota is influenced by several internal and external factors, including diet, age, disease, and lifestyle. Such changes, called dysbiosis, may be involved in the development of various conditions, such as metabolic diseases, including metabolic syndrome, type 2 diabetes mellitus, Hashimoto's thyroidis and Graves' disease; they can also play a role in nervous system disturbances, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, and depression. An association has also been found between gut microbiota dysbiosis and cancer. Our health is closely associated with the state of our microbiota, and their homeostasis. The aim of this review is to describe the associations between human gut microbiota and cancer, and examine the potential role of gut microbiota in anticancer therapy.

Quality of life as a therapeutic objective in the management of hepatic encephalopathy and the potential role of rifaximin-α

OBJECTIVE

Quality of life (QoL) is impaired in patients with hepatic encephalopathy and rifaximin-α can improve QoL within 6 months. This study assessed the importance of QoL as a therapeutic objective in hepatic encephalopathy management; whether QoL is routinely assessed in hepatic encephalopathy patients in clinical practice and the role of rifaximin-α in this context.

METHODS

A survey was conducted of healthcare professionals (HCPs) from Europe and Australia involved in hepatic encephalopathy management. HCPs rated the importance of a range of therapeutic objectives on a 1-7 Likert scale (1 = not at all important; 7 = extremely important). HCPs were also required to provide three patient record forms (PRFs) based on their last three hepatic encephalopathy patients.

RESULTS

There were 218 HCP respondents, who provided 654 PRFs (patients treated with rifaximin-α, n = 347; patients not treated with rifaximin-α, n = 307). The mean Likert score was highest for the therapeutic objective 'improving a patient's QoL' (6.4), which was rated significantly more highly than all other therapeutic objectives, including 'reducing the patient's likelihood of hospital readmission' (6.1; P < 0.001) and 'preventing death of the patient' (6.1; P < 0.001). Despite this, only 28.3% of PRFs documented specific QoL data assessment. Patients receiving rifaximin-α were treated later in their disease course than those not receiving rifaximin-α.

CONCLUSIONS

HCPs consider QoL improvement the main therapeutic objective in hepatic encephalopathy management, but most do not explicitly assess QoL. Earlier introduction of rifaximin-α may safeguard QoL improvement even when QoL monitoring is not possible.

Rifaximin-mediated gut microbiota regulation modulates the function of microglia and protects against CUMS-induced depression-like behaviors in adolescent rat

BACKGROUND

Chronic unpredictable mild stress (CUMS) can not only lead to depression-like behavior but also change the composition of the gut microbiome. Regulating the gut microbiome can have an antidepressant effect, but the mechanism by which it improves depressive symptoms is not clear. Short-chain fatty acids (SCFAs) are small molecular compounds produced by the fermentation of non-digestible carbohydrates. SFCAs are ubiquitous in intestinal endocrine and immune cells, making them important mediators of gut microbiome-regulated body functions. The balance between the pro- and anti-inflammatory microglia plays an important role in the occurrence and treatment of depression caused by chronic stress. Non-absorbable antibiotic rifaximin can regulate the structure of the gut microbiome. We hypothesized that rifaximin protects against stress-induced inflammation and depression-like behaviors by regulating the abundance of fecal microbial metabolites and the microglial functions.

METHODS

We administered 150 mg/kg rifaximin intragastrically to rats exposed to CUMS for 4 weeks and investigated the composition of the fecal microbiome, the content of short-chain fatty acids in the serum and brain, the functional profiles of microglia and hippocampal neurogenesis.

RESULTS

Our results show that rifaximin ameliorated depressive-like behavior induced by CUMS, as reflected by sucrose preference, the open field test and the Morris water maze. Rifaximin increased the relative abundance of Ruminococcaceae and Lachnospiraceae, which were significantly positively correlated with the high level of butyrate in the brain. Rifaximin increased the content of anti-inflammatory factors released by microglia, and prevented the neurogenic abnormalities caused by CUMS.

CONCLUSIONS

These results suggest that rifaximin can regulate the inflammatory function of microglia and play a protective role in pubertal neurodevelopment during CUMS by regulating the gut microbiome and short-chain fatty acids.

Rifaximin microbial resistance and its efficacy and safety as a secondary prophylaxis of hepatic encephalopathy in patients with hepatitis C virus-related cirrhosis

BACKGROUND AND AIM

Rifaximin is an oral antibiotic with promising efficacy in the reduction of hepatic encephalopathy (HE) recurrence. Development of microbial resistance to rifaximin is not studied yet in HE. The study aim was to assess the microbial resistance, safety and efficacy of rifaximin as secondary prophylaxis of HE.

METHOD

In this open-label parallel, prospective interventional study, 100 patients were randomly allocated either to receive 400 mg rifaximin 3 times/d plus 30-45 mL lactulose 3 times/d (intervention group) or to receive the standard of care only which is lactulose alone (control group) for 6 months. The primary outcome of the study was the difference between minimum inhibitory concentration (MIC) of rifaximin among the two studied groups at the end of treatment. The secondary outcomes included the time to first episode of HE, time to first hospitalisation, and patient's survival.

RESULTS

The MIC did not differ significantly after treatment exposure compared with baseline either between groups or within the same group. The time to new episode of HE was 18.84 ± 6.49 weeks (mean ± SD) in the intervention group and was significantly longer (P = .002) than that in the control group 14 ± 7.52 weeks. Moreover, only 23 (46%) patients developed overt HE in the intervention group compared with 35 patients (70%) in the control group (P = .005). Also, there was an observed 32% reduction in the risk of hospitalisation in intervention group compared with control group.

CONCLUSION

Rifaximin succeeded to maintain remission from new episodes of HE in hepatitis C virus cirrhotic patients with limited potential for development of microbial resistance over the study period. ClinicalTrials.gov Identifier: NCT04736836.

Probiotics combined with rifaximin influence the neurometabolic changes in a rat model of type C HE

Type C hepatic encephalopathy (HE) is a neuropsychiatric disease caused by chronic liver disease. Management of type C HE remains an important challenge because treatment options are limited. Both the antibiotic rifaximin and probiotics have been reported to reduce the symptoms of HE, but longitudinal studies assessing their effects on brain metabolism are lacking and the molecular mechanisms underpinning their effects are not fully understood. Therefore, we evaluated in detail the effects of these different treatments on the neurometabolic changes associated with type C HE using a multimodal approach including ultra-high field in vivo ¹H MRS. We analyzed longitudinally the effect of rifaximin alone or in combination with the probiotic Vivomixx on the brain metabolic profile in the hippocampus and cerebellum of bile duct ligated (BDL) rats, an established model of type C HE. Overall, while rifaximin alone appeared to induce no significant effect on the neurometabolic profile of BDL rats, its association with the probiotic resulted in more attenuated neurometabolic alterations in BDL rats followed longitudinally (i.e. a smaller increase in Gln and milder decrease in Glu and Cr levels). Given that both rifaximin and some probiotics are used in the treatment of HE, the implications of these findings may be clinically relevant.

Association between serum TNF-α and sarcopenia in liver cirrhosis

Background/Aims

Sarcopenia is an independent prognostic factor of liver cirrhosis (LC). However, the association between LC-related systemic inflammation and sarcopenia is unclear.

Methods

Sprague-Dawley rats were treated with thioacetamide (TAA) or saline as a control. Rifaximin was administered to TAA-induced LC rats. Enzyme-linked immunosorbent assay was performed to measure inflammatory mediators in rat serum. RT-PCR was performed to measure the molecular expression in tissues. Hematoxylin and eosin (H&E) staining and immunohistochemistry were performed to investigate tissue pathology. Serum tumor necrosis factor-α levels, liver stiffness (LS), and the L3 skeletal muscle index (L3SMI) were measured in 60 patients with chronic liver disease.

Results

LC and sarcopenia were successfully induced by TAA. Serum TNF-α levels were increased in LC rats and correlated with myostatin expression, muscle weight, and myofiber diameter. The expression of intestinal occludin and zona occludens-1 was reduced in LC rats and associated with serum TNF-α levels and sarcopenia. In patients with LS ≥7 kPa or sarcopenia, serum TNF-α levels were significantly increased, which was also confirmed when we raised the LS cutoff to 10 kPa. The L3SMI was inversely correlated with serum TNF-α levels in patients with LS ≥7 kPa. TNF-α was reduced by rifaximin, which might have resulted in reduced expression of muscular MuRF1 and myostatin and improvements in myofiber diameters within muscle tissues.

Conclusions

These results suggest that serum TNF-α is associated with LC-related sarcopenia. Rifaximin might be effective in reducing serum TNF-α levels and improving sarcopenia in LC, but these results need to be validated in future studies.

Fecal Microbiota Transplantation in Patients with HBV Infection or Other Chronic Liver Diseases: Update on Current Knowledge and Future Perspectives

Liver disease and gut dysbiosis are strictly associated, and the pathophysiology of this bidirectional relationship has recently been the subject of several investigations. Growing evidence highlights the link between gut microbiota composition, impairment of the gut-liver axis, and the development or progression of liver disease. Therefore, the modulation of gut microbiota to maintain homeostasis of the gut-liver axis could represent a potential instrument to halt liver damage, modify the course of liver disease, and improve clinical outcomes. Among all the methods available to achieve this purpose, fecal microbiota transplantation (FMT) is one of the most promising, being able to directly reshape the recipient’s gut microbial communities. In this review, we report the main characteristics of gut dysbiosis and its pathogenetic consequences in cirrhotic patients, discussing the emerging data on the application of FMT for liver disease in different clinical settings.

The role of the gut microbiome in graft fibrosis after pediatric liver transplantation

Liver transplantation (LT) is a life-saving option for children with end-stage liver disease. However, about 50% of patients develop graft fibrosis in 1 year after LT, with normal liver function. Graft fibrosis may progress to cirrhosis, resulting in graft dysfunction and ultimately the need for re-transplantation. Previous studies have identified various risk factors for the post-LT fibrogenesis, however, to date, neither of the factors seems to fully explain the cause of graft fibrosis. Recently, evidence has accumulated on the important role of the gut microbiome in outcomes after solid organ transplantation. As an altered microbiome is present in pediatric patients with end-stage liver diseases, we hypothesize that the persisting alterations in microbial composition or function contribute to the development of graft fibrosis, for example by bacteria translocation due to increased intestinal permeability, imbalanced bile acids metabolism, and/or decreased production of short-chain fatty acids (SCFAs). Subsequently, an immune response can be activated in the graft, together with the stimulation of fibrogenesis. Here we review current knowledge about the potential mechanisms by which alterations in microbial composition or function may lead to graft fibrosis in pediatric LT and we provide prospective views on the efficacy of gut microbiome manipulation as a therapeutic target to alleviate the graft fibrosis and to improve long-term survival after LT.

Therapeutic modulation methods of gut microbiota and gut-liver axis

Liver diseases are considered global health problems that cause more than 1 million deaths each year. Due to the increase in the prevalence of liver diseases worldwide, studies on different treatment methods have increased. Some of these methods is diagnostic and therapeutic applications based on the examination of the intestinal and intestinal microbiota. In this study, research articles, systematic review and review in the literature were examined in order to determine gut-liver axis relationship and treatment methods for liver diseases with gut modulation methods. Studies related to the subject have been searched in Google Scholar and Pubmed databases. The keywords "liver disease" and "gut-liver axis" and "microbiota" and "gut modulation methods" or "probiotic" or "prebiotic" or "symbiotic" or "antibiotic" or "bile acid regulation" or "adsorbent" or "fecal microbiota transplantation" were used in the searches. Improvements have been achieved in biomarkers of liver diseases by providing intestinal modulation with probiotic, prebiotic, symbiotic, antibiotic and adsorbents applications, bile acid regulation and fecal microbiota transplantation. In the results of experimental and clinical studies, it was seen that the therapeutic potential of the treatments performed by applying probiotics, prebiotics and symbiotics was higher.

Toll-Like Receptors Recognize Intestinal Microbes in Liver Cirrhosis

Liver cirrhosis is one major cause of mortality in the clinic, and treatment of this disease is an arduous task. The scenario will be even getting worse with increasing alcohol consumption and obesity in the current lifestyle. To date, we have no medicines to cure cirrhosis. Although many etiologies are associated with cirrhosis, abnormal intestinal microbe flora (termed dysbiosis) is a common feature in cirrhosis regardless of the causes. Toll-like receptors (TLRs), one evolutional conserved family of pattern recognition receptors in the innate immune systems, play a central role in maintaining the homeostasis of intestinal microbiota and inducing immune responses by recognizing both commensal and pathogenic microbes. Remarkably, recent studies found that correction of intestinal flora imbalance could change the progress of liver cirrhosis. Therefore, correction of intestinal dysbiosis and targeting TLRs can provide novel and promising strategies in the treatment of liver cirrhosis. Here we summarize the recent advances in the related topics. Investigating the relationship among innate immunity TLRs, intestinal flora disorders, and liver cirrhosis and exploring the underlying regulatory mechanisms will assuredly have a bright future for both basic and clinical research.

Low-dose rifaximin prevents complications and improves survival in patients with decompensated liver cirrhosis

BACKGROUND AND AIMS

Rifaximin has been recommended as a prophylactic drug for hepatic encephalopathy (HE) and spontaneous bacterial peritonitis (SBP). This study aims to explore whether low-dose rifaximin can prevent overall complications and prolong survival in cirrhotic patients.

METHODS

In this multi-centre randomized open-labelled prospective study, 200 patients with decompensated cirrhosis were randomly assigned at a ratio of 1:1. Patients in rifaximin group were administered 400 mg rifaximin twice daily for 6 months, and all other therapeutic strategies were kept unchanged in both groups as long as possible. The primary efficacy endpoints were the incidence of overall complications and liver transplantation-free survival. The secondary endspoints were the incidence of each major cirrhosis-related complication, as well as the Child-Pugh score and class.

RESULTS

The major baseline characteristics were similar in the two groups except for HE. The cumulative incidence and frequency of overall complications were significantly lower in rifaximin group than in the control group (p < 0.001). Though liver transplantation-free survival was not significantly different between the two groups, subgroup analysis showed rifaximin markedly prolonged liver transplantation-free survival in patients with Child-Pugh score ≥ 9 (p = 0.007). Moreover, rifaximin markedly reduced the episodes of ascites exacerbation (p < 0.001), HE (p < 0.001) and gastric variceal bleeding (EGVB, p = 0.031). The incidence of adverse events was similar in the two groups.

CONCLUSION

Low-dose rifaximin significantly decreases the occurrence of overall complications, leading to prolonged survival in patients with advanced stages of cirrhosis in this trail. Further study should be carried out to compare the effect of this low-dose rifaximin with normal dose (1200 mg/day) rifaximin in preventing cirrhosis-related complications.

CLINICAL TRIAL NUMBER

NCT02190357.

Gut microbiota mediated molecular events and therapy in liver diseases

Gut microbiota is a community of microorganisms that reside in the gastrointestinal tract. An increasing number of studies has demonstrated that the gut-liver axis plays a critical role in liver homeostasis. Dysbiosis of gut microbiota can cause liver diseases, including nonalcoholic fatty liver disease and alcoholic liver disease. Preclinical and clinical investigations have substantiated that the metabolites and other molecules derived from gut microbiota and diet interaction function as mediators to cause liver fibrosis, cirrhosis, and final cancer. This effect has been demonstrated to be associated with dysregulation of intrahepatic immunity and liver metabolism. Targeting these findings have led to the development of novel preventive and therapeutic strategies. Here, we review the cellular and molecular mechanisms underlying gut microbiota-mediated impact on liver disease. We also summarize the advancement of gut microbiota-based therapeutic strategies in the control of liver diseases.

Validation and Application of a Derivatization-Free RP-HPLC-DAD Method for the Determination of Low Molecular Weight Salivary Metabolites

Saliva is an interesting, non-conventional, valuable diagnostic fluid. It can be collected using standardized sampling device; thus, its sampling is easy and non-invasive, it contains a variety of organic metabolites that reflect blood composition. The aim of this study was to validate a user-friendly method for the simultaneous determination of low molecular weight metabolites in saliva. We have optimized and validated a high throughput, direct, low-cost reversed phase liquid chromatographic method with diode array detection method without any pre- or post-column derivatization. We indexed salivary biomolecules in 35 whole non-stimulated saliva samples collected in 8 individuals in different days, including organic acids and amino acids and other carbonyl compounds. Among these, 16 whole saliva samples were collected by a single individual over three weeks before, during and after treatment with antibiotic in order to investigate the dynamics of metabolites. The concentrations of the metabolites were compared with the literature data. The multianalyte method here proposed requires a minimal sample handling and it is cost-effectiveness as it makes possible to analyze a high number of samples with basic instrumentation. The identification and quantitation of salivary metabolites may allow the definition of potential biomarkers for non-invasive "personal monitoring" during drug treatments, work out, or life habits over time.

Effect of liver transplantation on intestinal permeability and correlation with infection episodes

Background

Liver cirrhosis has been known to be associated with increased intestinal permeability (IP); however, little is known about the modification of IP after liver transplantation (LT). The present study was aimed to assess IP after LT and evaluated its association with laboratory tests and clinical parameters, as well as with the development of infections.

Methods

LT recipients were consecutively enrolled and compared with an equal number of patients with liver cirrhosis and healthy subjects. IP was assessed by urinary excretion of chromium-51 ethylenediaminetetraacetic acid (⁵¹Cr-EDTA).

Results

The median ⁵¹Cr-EDTA excretion was found to be higher in 35 LT recipients as compared with that in the healthy controls [4.77% (2.79–6.03) vs. 2.07% (1.57–2.42), p<0.0001], and comparable to that in the cirrhotic patients [3.69% (2.34–6.57), p = 0.445]. ⁵¹Cr-EDTA excretion was not associated with clinical variables, the type of immunosuppressive therapy, donor-related factors, comorbidities and incidence of infections [infection/no infection: 4.97% (3.14–7.03) vs 4.62% (2.79–5.82), p = 0.938].

Conclusion

LT recipients show an increased IP, similar to that in patients with liver cirrhosis. However, it is not associated with a high risk of infections. Further investigations into the pathogenesis of this persistent impairment of the intestinal barrier are warranted.

Propranolol Reduces Portal Vein Diameter in Schistosomal Liver Disease with Portal Hypertension: A Prospective Cohort Study

Hepatosplenic schistosomiasis (HSS) complicates portal hypertension, leading to life-threatening variceal bleeding. Variceal bleeding is associated with increased portal vein diameter (PVD). Beta-blockers prevent variceal bleeding. It is unclear whether beta-blockers such as propranolol can reduce PVD in HSS. We aimed to explore the effect of propranolol on PVD in HSS. A longitudinal study was conducted at the University Teaching Hospital, Zambia, as an extension of a clinical trial of rifaximin undertaken to test the hypothesis that rifaximin could reduce bacterial translocation in HSS. We randomized 85 adults to either rifaximin and standard care, or propranolol-based standard care only for 42 days. We then followed up all the patients on propranolol up to day 180. We used ultrasound to measure PVD at baseline and day 180. The primary outcome was reduction in PVD. Beta-blockade and splenic size reduction were secondary outcomes. Portal vein diameter reduced after 180 days of propranolol therapy from median 12 mm (interquartile range (IQR): 11–14) to median 10 mm (IQR: 9–13) (P < 0.001). The pulse rate reduced from baseline median 70 beats/minute (IQR: 66–80) to 65 beats/minute (IQR: 60–70) by day 180 (P = 0.006). Hemoglobin levels improved from baseline median 8 g/dL (IQR: 6–11) to 12 g/dL (10–14) (P < 0.001). Splenic size remained unchanged. Propranolol led to the reduction in PVD over 180 days. This suggests that ultrasound could be useful in monitoring response and compliance to beta-blockers, especially in resource-constraint areas where portal hypertension measurement facilities are unavailable.

Evaluation of a Dual-Acting Antibacterial Agent, TNP-2092, on Gut Microbiota and Potential Application in the Treatment of Gastrointestinal and Liver Disorders

TNP-2092 is a unique multitargeting drug conjugate with extremely low propensity for development of resistance. The in vitro activity of TNP-2092 against a panel of urease-producing bacteria was similar to that of rifaximin, a locally acting antibiotic approved for the treatment of hepatic encephalopathy, irritable bowel syndrome with diarrhea, and traveler's diarrhea. When given orally, TNP-2092 exhibited low absorption and the majority of compound was recovered in feces as parent. The impact of oral TNP-2092 on gut microbiota was investigated in rats. TNP-2092 was administered to rats by oral gavage for 7 days. Feces samples were collected and analyzed by 16S rRNA sequencing. Although the total amount of bacterial load appeared relatively unchanged before, during, and after treatment, significant changes in the relative abundance of certain gut bacteria at family and genus levels were observed. Some of the changes are known to be associated with improvement of symptoms associated with liver cirrhosis and hepatic encephalopathy. The observed effects of TNP-2092 on gut microbiota in rats were similar to those of rifaximin. In vivo, TNP-2092 demonstrated potent efficacy in a mouse Clostridium difficile infection model, superior to metronidazole and vancomycin, with no relapse observed after treatment. TNP-2092 is currently in clinical development for the treatment of symptoms associated with gastrointestinal and liver disorders.

Rifaximin improves survival in cirrhotic patients with refractory ascites: A real-world study

BACKGROUND

Rifaximin has been shown to reduce the incidence of hepatic encephalopathy and other complications in patients with cirrhosis. However, few studies have investigated the effect of rifaximin in cirrhotic patients with refractory ascites.

AIM

To evaluate the effects of rifaximin in the treatment of refractory ascites and to preliminarily explore its possible mechanism.

METHODS

A total of 75 cirrhotic patients with refractory ascites were enrolled in the study (50 in a rifaximin and 25 in a control group). Patients in the rifaximin group were divided into two subgroups according to the presence of spontaneous bacterial peritonitis and treatment with or without other antibiotics (19 patients treated with rifaximin and 31 patients treated with rifaximin plus intravenous antibiotics). All patients received conventional treatment for refractory ascites, while patients in the rifaximin group received oral rifaximin-α 200 mg four times daily for at least 2 wk. The ascites grade, fasting weight, liver and kidney function, and inflammatory factors in the plasma were evaluated before and after treatment. In addition, the gut microbiota was determined by metagenomics sequencing to analyse the changes in the characteristics of the gut microbiota before and after rifaximin treatment. The patients were followed for 6 mo.

RESULTS

Compared with the control group, the fasting weight of patients significantly decreased and the ascites significantly subsided after treatment with rifaximin (P = 0.011 and 0.009, respectively). The 6-mo survival rate of patients in the rifaximin group was significantly higher than that in the control group (P = 0.048). The concentration of interferon-inducible protein 10 decreased significantly in the rifaximin group compared with that in the control group (P = 0.024). The abundance of Roseburia, Haemophilus, and Prevotella was significantly reduced after rifaximin treatment, while the abundance of Lachnospiraceae_noname, Subdoligranulum, and Dorea decreased and the abundance of Coprobacillus increased after treatment with rifaximin plus intravenous antibiotics. The gene expression of virulence factors was significantly reduced after treatment in both subgroups treated with rifaximin or rifaximin plus intravenous antibiotics.

CONCLUSION

Rifaximin mitigates ascites and improves survival of cirrhotic patients with refractory ascites. A possible mechanism is that rifaximin regulates the structure and function of intestinal bacteria, thus improving the systemic inflammatory state.

The role of splanchnic congestion and the intestinal microenvironment in the pathogenesis of advanced heart failure

PURPOSE OF REVIEW

Right-sided heart failure, which is often present in the setting of advanced heart failure, is associated with cardiac cachexia, the cardiorenal syndrome, and adverse outcomes. Improved understanding of venous congestion of the splanchnic circulation, which may play a key role in the pathogenesis of right-sided heart failure, could lead to novel therapeutics to ameliorate heart failure. Here we provide an overview of right-sided heart failure, splanchnic hemodynamics, fluid homeostasis, and the intestinal microenvironment. We review recent literature to describe pathophysiologic mechanisms and possible therapeutics.

RECENT FINDINGS

Several possible mechanisms centered around upregulation of sodium-hydrogen exchanger-3 (NHE3) may form a causal link between right ventricular dysfunction, splanchnic congestion, and worsening heart failure. These include an anaerobic environment in enterocytes, resulting in reduced intracellular pH; increased sodium absorption by the gut via NHE3; decreased pH at the intestinal brush border thus altering the gut microbiome profile; increased bacterial synthesis of trimethylamine N-oxide; and decreased bacterial synthesis of short-chain fatty acids causing abnormal intestinal barrier function.

SUMMARY

Splanchnic congestion in the setting of right-sided heart failure may serve an important role in the pathogenesis of advanced heart failure, and further exploration of these mechanisms may lead to new therapeutic advances.

HS-SPME-GC-MS approach for the analysis of volatile salivary metabolites and application in a case study for the indirect assessment of gut microbiota

In this work, a straightforward analytical approach based on headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was developed for the analysis of salivary volatile organic compounds without any prior derivatization step. With a sample volume of 500 μL, optimal conditions were achieved by allowing the sample to equilibrate for 10 min at 50 °C and then extracting the samples for 10 min at the same temperature, using a carboxen/polydimethylsiloxane fibre. The method allowed the simultaneous identification and quantification of 20 compounds in sample headspace, including short-chain fatty acids and their derivatives which are commonly analysed after analyte derivatization. The proof of applicability of the methodology was performed with a case study regarding the analysis of the dynamics of volatile metabolites in saliva of a single subject undergoing 5-day treatment with rifaximin antibiotic. Non-stimulated saliva samples were collected over 3 weeks from a nominally healthy volunteer before, during, and after antibiotic treatment. The variations of some metabolites, known to be produced by the microbiota and by bacteria that are susceptible to antibiotics, suggest that the study of the dynamics of salivary metabolites can be an excellent indirect method for analysing the gut microbiota. This approach is novel from an analytical standpoint, and it encourages further studies combining saliva metabolite profiles and gut microbiota dynamics. Graphical abstract.

Intestinal permeability in the pathogenesis of liver damage: From non-alcoholic fatty liver disease to liver transplantation

The intimate connection and the strict mutual cooperation between the gut and the liver realizes a functional entity called gut-liver axis. The integrity of intestinal barrier is crucial for the maintenance of liver homeostasis. In this mutual relationship, the liver acts as a second firewall towards potentially harmful substances translocated from the gut, and is, in turn, is implicated in the regulation of the barrier. Increasing evidence has highlighted the relevance of increased intestinal permeability and consequent bacterial translocation in the development of liver damage. In particular, in patients with non-alcoholic fatty liver disease recent hypotheses are considering intestinal permeability impairment, diet and gut dysbiosis as the primary pathogenic trigger. In advanced liver disease, intestinal permeability is enhanced by portal hypertension. The clinical consequence is an increased bacterial translocation that further worsens liver damage. Furthermore, this pathogenic mechanism is implicated in most of liver cirrhosis complications, such as spontaneous bacterial peritonitis, hepatorenal syndrome, portal vein thrombosis, hepatic encephalopathy, and hepatocellular carcinoma. After liver transplantation, the decrease in portal pressure should determine beneficial effects on the gut-liver axis, although are incompletely understood data on the modifications of the intestinal permeability and gut microbiota composition are still lacking. How the modulation of the intestinal permeability could prevent the initiation and progression of liver disease is still an uncovered area, which deserves further attention.

Infectious Threats, the Intestinal Barrier, and Its Trojan Horse: Dysbiosis

The ecosystem of the gut microbiota consists of diverse intestinal species with multiple metabolic and immunologic activities and it is closely connected with the intestinal epithelia and mucosal immune response, with which it builds a complex barrier against intestinal pathogenic bacteria. The microbiota ensures the integrity of the gut barrier through multiple mechanisms, either by releasing antibacterial molecules (bacteriocins) and anti-inflammatory short-chain fatty acids or by activating essential cell receptors for the immune response. Experimental studies have confirmed the role of the intestinal microbiota in the epigenetic modulation of the gut barrier through posttranslational histone modifications and regulatory mechanisms induced by epithelial miRNA in the epithelial lumen. Any quantitative or functional changes of the intestinal microbiota, referred to as dysbiosis, alter the immune response, decrease epithelial permeability and destabilize intestinal homeostasis. Consequently, the overgrowth of pathobionts (Staphylococcus, Pseudomonas, and Escherichia coli) favors intestinal translocations with Gram negative bacteria or their endotoxins and could trigger sepsis, septic shock, secondary peritonitis, or various intestinal infections. Intestinal infections also induce epithelial lesions and perpetuate the risk of bacterial translocation and dysbiosis through epithelial ischemia and pro-inflammatory cytokines. Furthermore, the decline of protective anaerobic bacteria (Bifidobacterium and Lactobacillus) and inadequate release of immune modulators (such as butyrate) affects the release of antimicrobial peptides, de-represses microbial virulence factors and alters the innate immune response. As a result, intestinal germs modulate liver pathology and represent a common etiology of infections in HIV immunosuppressed patients. Antibiotic and antiretroviral treatments also promote intestinal dysbiosis, followed by the selection of resistant germs which could later become a source of infections. The current article addresses the strong correlations between the intestinal barrier and the microbiota and discusses the role of dysbiosis in destabilizing the intestinal barrier and promoting infectious diseases.

The rise of Clostridioides difficile infections and fall of associated mortality in hospitalized advanced cirrhotics

BACKGROUND & AIMS

Cirrhotics are at increased risk of Clostridioides difficile infection (CDI) and its associated high morbidity and mortality. However, the impact of CDI in cirrhotics over time remains unclear. This study analyses prevalence and mortality in CDI in hospitalized patients with advanced cirrhosis over 15 years and identifies trends.

METHODS

Using the Nationwide Inpatient Sample (NIS) from 1998 to 2014, 3 049 696 weighted patients with advanced cirrhosis (defined as evidence of decompensation or oesophageal varices) were identified using a validated algorithm of ICD-9-CM codes and included in the study. Trends were analysed using Cochran Armitage test and joinpoint regression and compared to the general population. Multivariable logistic regression was performed controlling for risk factors that affect mortality in cirrhotics.

RESULTS

CDI prevalence in advanced cirrhotics increased from 0.8% to 2.6%, annual percent change (APC) 8.8% (compared to 7.6% for the general population), while CDI-related mortality decreased from 20.7% to 11.3%, APC -3.4% (compared to -2.0% for the general population), from 1998 to 2014. CDI independently increased mortality in advanced cirrhotics (OR 1.47, P < 0.001) and was associated with acute kidney injury (AKI) (OR 2.09, P < 0.001), which itself significantly increased mortality (OR 4.54, P < 0.001). Hepatic encephalopathy and Hispanic ethnicity were interestingly associated with a lower prevalence of CDI.

CONCLUSIONS

CDI is increasingly common in advanced cirrhotics, but on the contrary, its associated mortality is decreasing. Despite improvements in outcomes in patients with advanced cirrhosis, CDI is associated with an increased mortality, driven by AKI, and therefore, requires aggressive identification and therapy.

Dietary approach and gut microbiota modulation for chronic hepatic encephalopathy in cirrhosis

Hepatic encephalopathy (HE) is a common and serious neuropsychiatric complication of cirrhosis, acute liver failure, and porto-systemic shunting. HE largely contributes to the morbidity of patients with liver disease, severely affecting the quality of life of both patients and their relatives and being associated with poor prognosis. Its presentation is largely variable, manifesting with a broad spectrum of cognitive abnormalities ranging from subtle cognitive impairment to coma. The pathogenesis of HE is complex and has historically been linked with hyperammonemia. However, in the last years, it has become evident that the interplay of multiple actors, such as intestinal dysbiosis, gut hyperpermeability, and neuroinflammation, is of crucial importance in its genesis. Therefore, HE can be considered a result of a dysregulated gut-liver-brain axis function, where cognitive impairment can be reversed or prevented by the beneficial effects induced by "gut-centric" therapies, such as non-absorbable disaccharides, non-absorbable antibiotics, probiotics, prebiotics, and fecal microbiota transplantation. In this context dietary modifications, by modulating the intestinal milieu, can also provide significant benefit to cirrhotic patients with HE. This review will provide a comprehensive insight into the mechanisms responsible for gut-liver-brain axis dysregulation leading to HE in cirrhosis. Furthermore, it will explore the currently available therapies and the most promising future treatments for the management of patients with HE, with a special focus on the dietary approach.

Diagnostic and therapeutic potential of the gut microbiota in patients with early hepatocellular carcinoma

The gut microbiota is involved in the maintenance of the homeostasis of the human body and its alterations are associated with the development of different pathological conditions. The liver is the organ most exposed to the influence of the gut microbiota, and recently important connections between the intestinal flora and hepatocellular carcinoma (HCC) have been described. In fact, HCC is commonly associated with liver cirrhosis and develops in a microenvironment where inflammation, immunological alterations, and cellular aberrations are dramatically evident. Prevention and diagnosis in the earliest stages are still the most effective weapons in fighting this tumor. Animal models show that the gut microbiota can be involved in the promotion and progression of HCC directly or through different pathogenic mechanisms. Recent data in humans have confirmed these preclinical findings, shedding new light on HCC pathogenesis. Limitations due to the different experimental design, the ethnic and hepatological setting make it difficult to compare the results and draw definitive conclusions, but these studies lay the foundations for a pathogenetic redefinition of HCC. Therefore, it is evident that the characterization of the gut microbiota and its modulation can have an enormous diagnostic, preventive, and therapeutic potential, especially in patients with early stage HCC.

Rifaximin Alters Intestinal Microbiota and Prevents Progression of Ankylosing Spondylitis in Mice

Recently, accumulating evidence has suggested that gut microbiota may be involved in the occurrence and development of ankylosing spondylitis (AS). It has been suggested that rifaximin have the ability to modulate the gut bacterial communities, prevent inflammatory response, and modulate gut barrier function. The goal of this work is to evaluate the protective effects of rifaximin in fighting AS and to elucidate the potential underlying mechanism. Rifaximin were administered to the proteoglycan (PG)-induced AS mice for 4 consecutive weeks. The disease severity was measured with the clinical and histological of arthritis and spondylitis. Intestinal histopathological, pro-inflammatory cytokine levels and the intestinal mucosal barrier were evaluated. Then, western blot was performed to explore the toll-like receptor 4 (TLR-4) signal transducer and NF-κB expression. Stool samples were collected to analyze the differences in the gut microbiota via next-generation sequencing of 16S rDNA. We found that rifaximin significantly reduced the severity of AS and resulted in down-regulation of inflammatory factors, such as TNF-α, IL-6, IL-17A, and IL-23. Meanwhile, rifaximin prevented ileum histological alterations, restored intestinal barrier function and inhibited TLR-4/NF-κB signaling pathway activation. Rifaximin also changed the gut microbiota composition with increased Bacteroidetes/Firmicutes phylum ratio, as well as selectively promoting some probiotic populations, including Lactobacillales. Our results suggest that rifaximin suppressed progression of AS and regulated gut microbiota in AS mice. Rifaximin might be useful as a novel treatment for AS.

Hepatic encephalopathy 2018: A clinical practice guideline by the Italian Association for the Study of the Liver (AISF)

Hepatic encephalopathy (HE) is a common, worrisome and sometimes difficult to manage complication of end-stage liver disease. HE is often recurrent, requiring multiple hospital admissions. It can have serious implications in terms of a patient's ability to perform complex tasks (for example driving), their earning capacity, their social and family roles. This guideline reviews current knowledge on HE definition, pathophysiology, diagnosis and treatment, both by general principles and by way of a summary of available drugs and treatment strategies. The quality of the published, pertinent evidence is graded, and practical recommendations are made. Where possible, these are placed within the Italian health service context, with reference to local diagnosis and management experience.

Chinese guidelines on the management of ascites and its related complications in cirrhosis

The Chinese Society of Hepatology developed the current guidelines for the Management of Ascites and Its Related Complications in Cirrhosis based on the published evidences and the panelists' consensus. The guidelines provided recommendations for the diagnosis and management of cirrhotic ascites emphasizing a step-wise approach with the first-, second-, and third-line therapy. For refractory ascites, vasoconstrictors and albumin are recommended for splanchnic vasodilation and selective vasopressin (V2) receptor antagonists for moderate-to-severe hyponatremia. For spontaneous bacterial peritonitis, empirical anti-infection treatment was recommended based on the local microbiological examination of community- or hospital-acquired infections. For hepatorenal syndrome, the administration of vasopressor terlipressin and albumin is recommended.

New concepts on intestinal microbiota and the role of the non-absorbable antibiotics with special reference to rifaximin in digestive diseases

Digestive diseases are a broad range of chronic disorders that substantially and negatively impact the patients' quality of life. Here, we review our current understanding on the pathophysiology of hepatic encephalopathy, irritable bowel syndrome, and diverticular disease, with a special focus on the gut microbiota composition associated with these disorders. Furthermore, we review the current clinical practice for their therapeutic treatments, including probiotics, diet change, non-adsorbable disaccharides, and antibiotics. We highlight that broad-spectrum non-adsorbable antibiotics, such as rifaximin, are quite effective and safe for the treatment of all essayed digestive diseases.

Rifaximin as a rare cause of rhabdomyolysis in cirrhosis

Rifaximin has only been rarely reported to cause rhabdomyolysis. When physical and nonphysical etiologies have been excluded, thorough review of the patient's medication list is necessary. In cirrhotics, the potential harm of rifaximin in treatment or prophylaxis of hepatic encephalopathy should be recognized.

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.

Rifaximin and Propranolol Combination Therapy Is More Effective than Propranolol Monotherapy for the Reduction of Portal Pressure: An Open Randomized Controlled Pilot Study

Background/Aims

Non-selective beta blockers (NSBBs) are currently the only accepted regimen for preventing portal hypertension (PHT)-related complications. However, the effect of NSBBs is insufficient in many cases. Bacterial translocation (BT) is one of the aggravating factors of PHT in cirrhosis; therefore, selective intestinal decontamination by rifaximin is a possible therapeutic option for improving PHT. We investigated whether the addition of rifaximin to propranolol therapy can improve hepatic venous pressure gradient (HVPG) response.

Methods

Sixty-four cirrhosis patients were randomly assigned to propranolol monotherapy (n=48) versus rifaximin and propranolol combination therapy (n=16). Baseline and post-treatment HVPG values, BT-related markers (lipopolysaccharide [LPS], LPS-binding protein [LBP], interleukin-6 [IL-6], and tumor necrosis factor α [TNF-α]), serological data, and adverse event data were collected. HVPG response rate was the primary endpoint.

Results

Combination therapy was associated with better HVPG response rates than monotherapy (56.2% vs 87.5%, p=0.034). In combination therapy, posttreatment BT-related markers were significantly decreased (LPS, p=0.005; LBP, p=0.005; IL-6, p=0.005; TNF-α, p=0.047).

Conclusions

Rifaximin combination therapy showed an additive effect in improving PHT compared to propranolol monotherapy. These pilot data suggest that the addition of rifaximin to NSBBs could be a good therapeutic option for overcoming the limited effectiveness of NSBBs.