Randomised clinical trial: the effects of a multispecies probiotic vs. placebo on innate immune function, bacterial translocation and gut permeability in patients with cirrhosis

Probiotics are beneficial for liver cirrhosis: a systematic review and meta-analysis of randomized control trials

Introduction

Gut dysbiosis may play a pivotal role in the pathogenesis of cirrhosis and the severity of complications. Numerous studies have investigated the probiotics as treatments for cirrhosis. However, there is still a lack of definitive evidence confirming the beneficial effects of probiotics on cirrhosis.

Methods

Databases including PubMed, Embase, Web of Science, and the Cochrane Library were systematically searched for randomized controlled trials that compared the effects of probiotic intervention and control treatments, including placebo, no treatment, and active control, on cirrhosis, published from inception to February 2024. Outcomes included hepatic encephalopathy (HE) reversal, safety and tolerability of probiotics, liver function, quality of life, and other cirrhotic-related outcomes. A meta-analysis was conducted to synthesize evidence.

Results

Thirty studies were included. The quantitative synthesis results showed that compared with the control group, probiotics significantly reverse minimal hepatic encephalopathy (MHE) (risk ratio [RR] 1.54, 95% confidence interval [CI] 1.03 to 2.32) and improve HE (RR 1.94, 95% CI 1.24 to 3.06). Additionally, probiotics demonstrated higher safety and tolerability by causing a lower incidence of serious adverse events (RR 0.71, 95% CI 0.58 to 0.87). Probiotics could potentially improve liver function by reducing the Model for End-Stage Liver Disease (MELD) scores (standardized mean difference [SMD] -0.57, 95% CI -0.85 to -0.30), and displayed favorable changes in quality of life (SMD 0.51, 95% CI 0.27 to 0.75) and gut flora (SMD 1.67, 95% CI 1.28 to 2.06).

Conclusion

This systematic review and meta-analysis offers compelling evidence that probiotics are beneficial for cirrhosis by demonstrating reversal of HE, potential for liver function improvements, enhancements in quality of life, and regulation of gut dysbiosis. Furthermore, the apparent safety profile suggests that probiotics are a promising intervention for treating cirrhosis.

Clinical trial registration number

CRD42023478380.

Primary sarcopenia is associated with elevated spontaneous NET formation

Introduction: Sarcopenia is a frequent complication of liver cirrhosis, but it can also occur independently as a result of any underlying cause. The immune system plays an important role in the pathogenesis of both liver cirrhosis and sarcopenia. Neutrophil function, including neutrophil extracellular trap (NET) formation, is linked to chronic inflammation; however, it has not been extensively studied in patients with sarcopenia. Here, we aim to study if main neutrophil functions, such as phagocytosis, reactive oxygen species (ROS) production, and NET formation, are altered in patients with sarcopenia with or without liver cirrhosis. Methods: Neutrophils from 92 patients (52 patients with liver cirrhosis and sarcopenia, 25 patients with liver cirrhosis without sarcopenia, and 15 patients with sarcopenia without liver cirrhosis) and 10 healthy controls were isolated and stimulated with heat-inactivated E. coli (250 bacteria/cell), phorbol 12-myristate 13-acetate (PMA) (100 nM), or incubation medium in duplicates for 2 h at 37°C. Cells were fixed with paraformaldehyde and stained with 4',6-diamidino-2-phenylindole (DAPI). Pictures of 10 random fields of vision per slide were taken with an Olympus BX51 fluorescence microscope (Olympus, Shinjuku, Tokyo, Japan) at 600x total magnification. The DNA Area and NETosis Analysis (DANA) algorithm was used to quantify the percentage of NET formation per patient. Phagocytosis and ROS production were assessed with the PhagotestTM kit and PhagoburstTM kit (Glycotope, Heidelberg, Germany) in 92 patients and 21 healthy controls, respectively. Results: Spontaneous NET formation was significantly elevated in patients with only sarcopenia compared to patients with cirrhosis and sarcopenia (p = 0.008) and healthy controls (p = 0.039). NET formation in response to PMA was significantly decreased in patients with cirrhosis (p = 0.007), cirrhosis and sarcopenia (p < 0.001), and sarcopenia (p = 0.002) compared to healthy controls. There was no significant difference in NET formation in response to E. coli between the groups. The DANA algorithm was successfully optimized and validated for assessment of clinical samples. There were no significant changes in neutrophil phagocytosis between patients' groups compared to healthy controls. A significantly lower percentage of neutrophils produced ROS in response to N-formylmethionine-leucyl-phenylalanine (fMLF) in patients compared to healthy controls. Discussion: Spontaneous NET formation might contribute to chronic inflammation and sarcopenia pathogenesis. This, however, does not result in the impairment of the NET formation function of neutrophils in response to a bacterial stimulus and, therefore, cannot be not linked with the increased risk of bacterial infections neither in sarcopenia nor in cirrhosis. The semi-automated NET formation analysis can be successfully implemented to analyze the vast amount of data generated within clinical studies. This approach opens up the possibilities to develop an NET formation-based biomarker in different diseases including sarcopenia and implement NET formation analysis into clinical settings. Phagocytosis and ROS production were not affected in patients with sarcopenia. Further research is needed to explore the mechanism of NET formation in patients with sarcopenia and its potential as a biomarker in sarcopenia.

Effect of albumin infusion on oxidative albumin modification and albumin binding capacity in chronic liver failure

Oxidative albumin modification and impaired albumin binding function have been described both in chronic liver failure and for therapeutic albumin solutions. The aim of the present study was to evaluate the effect of albumin infusion on redox state and binding function of circulating albumin. We studied 20 patients with cirrhosis who routinely received albumin infusions for prevention of post-paracentesis circulatory dysfunction or treatment of hepatorenal syndrome. We measured albumin fractions by redox state of cysteine-34 and albumin binding properties using dansylsarcosine as site II ligand. Therapeutic albumin solutions showed high contents of human nonmercaptalbumin-1 and human nonmercaptalbumin-2, exceeding the respective values in our patients with decompensated cirrhosis. An initial protocol for the first nine patients sampled at baseline, 24 h and 48 h after albumin infusion revealed no significant changes of oxidized albumin species or albumin binding properties. However, a modified protocol for the remaining 11 patients sampled at baseline, <1 h after and 24 h after albumin infusion revealed short-lived changes of oxidized albumin species while no changes in albumin binding properties were observed. In conclusion, therapeutic albumin infusion transiently changed albumin redox state but did not improve binding function of circulating albumin in chronic liver failure.

Gut microbiota, intestinal permeability, and systemic inflammation: a narrative review

The intestine is the largest interface between the internal body and the external environment. The intestinal barrier is a dynamic system influenced by the composition of the intestinal microbiome and the activity of intercellular connections, regulated by hormones, dietary components, inflammatory mediators, and the enteric nervous system (ENS). Over the years, it has become increasingly evident that maintaining a stable intestinal barrier is crucial to prevent various potentially harmful substances and pathogens from entering the internal environment. Disruption of the barrier is referred to as 'leaky gut' or leaky gut wall syndrome and seems to be characterized by the release of bacterial metabolites and endotoxins, such as lipopolysaccharide (LPS), into the circulation. This condition, mainly caused by bacterial infections, oxidative stress, high-fat diet, exposure to alcohol or chronic allergens, and dysbiosis, appear to be highly connected with the development and/or progression of several metabolic and autoimmune systemic diseases, including obesity, non-alcoholic fatty liver disease (NAFLD), neurodegeneration, cardiovascular disease, inflammatory bowel disease, and type 1 diabetes mellitus (T1D). In this review, starting from a description of the mechanisms that enable barrier homeostasis and analyzing the relationship between this complex ecosystem and various pathological conditions, we explore the role of the gut barrier in driving systemic inflammation, also shedding light on current and future therapeutic interventions.

The Anti-Inflammatory and Curative Exponent of Probiotics: A Comprehensive and Authentic Ingredient for the Sustained Functioning of Major Human Organs

Several billion microorganisms reside in the gastrointestinal lumen, including viruses, bacteria, fungi, and yeast. Among them, probiotics were primarily used to cure digestive disorders such as intestinal infections and diarrhea; however, with a paradigm shift towards alleviating health through food, their importance is large. Moreover, recent studies have changed the perspective that probiotics prevent numerous ailments in the major organs. Probiotics primarily produce biologically active compounds targeting discommodious pathogens. This review demonstrates the implications of using probiotics from different genres to prevent and alleviate ailments in the primary human organs. The findings reveal that probiotics immediately activate anti-inflammatory mechanisms by producing anti-inflammatory cytokines such as interleukin (IL)-4, IL-10, IL-11, and IL-13, and hindering pro-inflammatory cytokines such as IL-1, IL-6, and TNF-α by involving regulatory T cells (Tregs) and T helper cells (Th cells). Several strains of Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus reuteri, Bifidobacterium longum, and Bifidobacterium breve have been listed among the probiotics that are excellent in alleviating various simple to complex ailments. Therefore, the importance of probiotics necessitates robust research to unveil the implications of probiotics, including the potency of strains, the optimal dosages, the combination of probiotics, their habitat in the host, the host response, and other pertinent factors.

Immune biomarkers in non-treatment-seeking heavy drinkers who used a probiotic supplement for 30 days: An open-label pilot study

Alcohol use disorder (AUD) is associated with significant psychological and economic burdens, as well as physical comorbidities that can lead to death. Previous research has found that probiotics may reduce inflammatory biomarkers in persons with AUD and comorbid conditions such as cirrhosis of the liver. This relationship has not been explored in heavy drinkers without comorbid conditions. In a proof-of-concept study, individuals who were heavy drinkers without known comorbidities received a 30-day course of a daily probiotic supplement in an open-label pilot trial. Eligible participants (N = 16) met NIAAA guidelines for heavy alcohol use and did not report any preexisting medical problems. Blood samples were taken at four timepoints: prior to the probiotic course, at the midpoint, at the end, and after a washout period of at least one month. Immunoassays were conducted on plasma samples to quantify the following inflammatory biomarkers: IL-6, IL-8, IL-10, LBP, MCP-1, sCD14, sCD163, and TNF-α. Linear mixed models were used to test within-subjects changes in biomarker concentrations over the study period, with alcohol use included as a time-varying covariate. Biomarker concentrations did not change significantly. A higher number of heavy drinking days was statistically associated with higher concentrations of IL-6 (F(1,8) = 6.66, p = 0.0326) and IL-8 (F(1,17) = 6.38, p = 0.0218). Greater days since last drink was associated with a lower concentration of MCP-1 (F(1,17) = 5.77, p = 0.028). In summary, biomarker trajectories were associated with alcohol consumption variables, but not probiotic use, in this open-label pilot study. Randomized controlled trials are needed to evaluate fully the potential benefits of probiotics in heavy drinkers without known comorbidities and under conditions of non-abstinence.

Exploring the Relationship between Liver Disease, Bacterial Translocation, and Dysbiosis: Unveiling the Gut-Liver Axis

Background

The global burden of liver disease and cirrhosis has been progressively increasing in the last decade. The interplay between gut microbiota and immune system and the bidirectional relationship with the liver, known as the gut-liver axis, has arisen as a fundamental aspect of liver disease.

Summary

Alterations of the gut microbiome have been described and include both dysbiotic microbial signatures and intestinal bacterial overgrowth. The integrity of the intestinal epithelial barrier is essential for preventing the access of harmful substances and bacterial products into the host. Bacterial translocation due to altered host-microbiota interactions triggers local immune cell activation and facilitates a chronic inflammatory state that can ultimately lead to immune exhaustion, characteristic of cirrhosis. In cirrhosis, breakdown of the gut vascular barrier allows access of bacterial products to portal blood circulation and facilitates their influx into the liver, further contributing to disease progression.

Key Messages

A better understanding of the contributing factors to pathological bacterial translocation and the impact of dysbiosis in liver disease will lead to achieve innovative therapeutic strategies in cirrhosis.

Gut microbes in metabolic disturbances. Promising role for therapeutic manipulations?

The prevalence of overweight, obesity, type 2 diabetes, metabolic syndrome and steatotic liver disease is rapidly increasing worldwide with a huge economic burden in terms of morbidity and mortality. Several genetic and environmental factors are involved in the onset and development of metabolic disorders and related complications. A critical role also exists for the gut microbiota, a complex polymicrobial ecology at the interface of the internal and external environment. The gut microbiota contributes to food digestion and transformation, caloric intake, and immune response of the host, keeping the homeostatic control in health. Mechanisms of disease include enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability and translocation of bacterial metabolites which activate a chronic low-grade systemic inflammation and insulin resistance, as precursors of tangible metabolic disorders involving glucose and lipid homeostasis. The ultimate causative role of gut microbiota in this respect remains to be elucidated, as well as the therapeutic value of manipulating the gut microbiota by diet, pre- and pro- synbiotics, or fecal microbial transplantation.

Circulating neutrophil anti-pathogen dysfunction in cirrhosis

Neutrophils are the largest population of leucocytes and are among the first cells of the innate immune system to fight against intruding pathogens. In patients with cirrhosis, neutrophils exhibit altered functionality, including changes in phagocytic ability, bacterial killing, chemotaxis, degranulation, reactive oxygen species production and NET (neutrophil extracellular trap) formation. This results in their inability to mount an adequate antibacterial response and protect the individual from infection. Prognosis and survival in patients with cirrhosis are greatly influenced by the development of infectious complications. Multidrug-resistant bacterial infections in patients with cirrhosis are currently a growing problem worldwide; therefore, alternative methods for the prevention and treatment of bacterial infections in cirrhosis are urgently needed. The prevention and treatment of neutrophil dysfunction could be a potential way to protect patients from bacterial infections. However, the reasons for changes in neutrophil function in cirrhosis are still not completely understood, which limits the development of efficient therapeutic strategies. Both cellular and serum factors have been proposed to contribute to the functional impairment of neutrophils. Herein, we review the current knowledge on features and proposed causes of neutrophil dysfunction in cirrhosis, with a focus on current knowledge gaps and limitations, as well as opportunities for future investigations in this field.

Do gut microbiome-targeted therapies improve liver function in cirrhotic patients? A systematic review and meta-analysis

BACKGROUND AND AIM

Microbiome-targeted therapies (MTTs) are considered as promising interventions for cirrhosis, but the impact of gut microbiome modulation on liver function and disease severity has not been fully assessed. We comprehensively evaluated the efficacy of MTTs in patients with liver cirrhosis.

METHODS

Data from randomized controlled trials were collected through MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and ClinicalTrial.gov from inception to February 20, 2023. Clinical outcomes were pooled and expressed in terms of risk ratios or mean differences (MD). Additional subgroup and sensitivity analyses were performed to validate the robustness of findings. A trial sequential analysis was applied to calculate the required information size and evaluate the credibility of the meta-analysis results.

RESULTS

Twenty-one studies with a total of 1699 cirrhotic patients were included for meta-analysis. MTTs were associated with a significant reduction in aspartate aminotransferase (MD, -3.62; 95% CI, -6.59 to -0.65), the risk of hepatic encephalopathy (risk ratio = 0.56, 95% CI: 0.46 to 0.68), model for end-stage liver disease score (MD, -0.90; 95% CI, -1.17 to -0.11), ammonia (MD, -11.86; 95% CI, -16.39 to -7.33), and endotoxin (MD, -0.14; 95% CI, -0.23 to -0.04). The trial sequential analysis yielded reliable results of these outcomes. No effects were observed on the changes of other hepatic function indicators.

CONCLUSION

MTTs appeared to be associated with a slowed deterioration in liver cirrhosis, which could provide reference for clinicians in treatment of cirrhotic patients based on their conditions.

The role of neutrophils in alcohol-related hepatitis

Alcohol-related liver disease is a major cause of liver disease-associated mortality, with inpatient care being a major contributor to its clinical and economic burden. Alcohol-related hepatitis (AH) is an acute inflammatory form of alcohol-related liver disease. Severe AH is associated with high short-term mortality, with infection being a common cause of death. The presence of AH is associated with increased numbers of circulating and hepatic neutrophils. We review the literature on the role of neutrophils in AH. In particular, we explain how neutrophils are recruited to the inflamed liver and how their antimicrobial functions (chemotaxis, phagocytosis, oxidative burst, NETosis) may be altered in AH. We highlight evidence for the existence of 'high-density' and 'low-density' neutrophil subsets. We also describe the potentially beneficial roles of neutrophils in the resolution of injury in AH through their effects on macrophage polarisation and hepatic regeneration. Finally, we discuss how manipulation of neutrophil recruitment/function may be used as a therapeutic strategy in AH. For example, correction of gut dysbiosis in AH could help to prevent excess neutrophil activation, or treatments could aim to enhance miR-223 function in AH. The development of markers that can reliably distinguish neutrophil subsets and of animal models that accurately reproduce human disease will be crucial for facilitating translational research in this important field.

Fungal translocation measured by serum 1,3-ß-D-glucan correlates with severity and outcome of liver cirrhosis-A pilot study

BACKGROUND & AIMS

On a global scale, liver cirrhosis is attributable to ~1 million deaths per year. This systemic disease comes along with diverse sequelae, including microbiota alterations, increased gut permeability and translocation of microbial components into the systemic circulation. Alongside the extensively studied influence of bacterial translocation and its host-pathogen interactions, far less is known about the role and impact of fungal components once having crossed the intestinal barrier.

METHODS

Including 70 patients with different aetiologies of liver cirrhosis, we investigated the relationship between fungal translocation, measured by 1,3-β-D-glucan (BDG), and biomarkers of gut integrity, inflammation and severity/outcome of liver disease.

RESULTS

Patients with cirrhosis Child-Pugh class (CPC)-B were more likely to have positive serum BDG (aOR 5.4, 95% CI 1.2-25.2) compared to patients with cirrhosis CPC-A. BDG showed a moderate positive correlation with several markers of inflammation (sCD206, sCD163, Interleukin 8, interferon-gamma-induced protein). Mortality differed significantly between patients with positive versus negative BDG (log-rank test, p = 0.015). The multivariable Cox regression model yielded an aHR of 6.8 (95% CI 1.8-26.3).

DISCUSSION

We observed trends for increased fungal translocation depending on the severity of liver cirrhosis, an association of BDG with an inflammatory environment and the adverse effects of BDG on disease outcome. In order to gain more in-depth knowledge about (fungal-)dysbiosis and its detrimental consequences in the setting of liver cirrhosis, these trends need to be studied in more detail including prospective sequential testing in larger cohorts together with mycobiome analyses. This will further elucidate complex host-pathogen interactions and potentially introduce points of application for therapeutic interventions.

Anti-CD20 treatment and neutrophil function in central nervous system demyelinating diseases

INTRODUCTION

A contribution of neutrophil granulocytes to the pathogenesis of multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) is recognized. Anti-CD20 treatments applied in these diseases are associated with infectious complications and neutropenia. No data is available about functional characteristics of neutrophils obtained from patients with anti-CD20 treatments.

METHODS

In neutrophils isolated from 13 patients with anti-CD20 treatment (9 MS, 4 NMOSD), 11 patients without anti-CD20 treatment (9 MS, 2 NMOSD) and 5 healthy controls, we analyzed chemotaxis, production of reactive oxygen species (ROS), phagocytosis, and formation of neutrophil extracellular traps (NET) in vitro.

RESULTS

Chemotaxis and ROS production were found unchanged between patients with and without anti-CD20 treatment or between patients and healthy controls. We found a higher proportion of non-phagocytosing cells in patients without anti-CD20 treatment compared to patients with anti-CD20 treatment and healthy controls. As compared to healthy controls, a higher proportion of neutrophils from patients without anti-CD20 treatments underwent NET formation, either unstimulated or stimulated with phorbol 12-myristate 3-acetate for 3 h. In about half of patients with anti-CD20 treatment (n = 7), NET formation of unstimulated neutrophils occurred already within 20 min of incubation. This was not observed in patients without anti-CD20 treatment and healthy controls.

CONCLUSION

Anti-CD20 treatment in MS and NMOSD patients does not alter chemotaxis and ROS production of neutrophils in vitro but might restore their impaired phagocytosis in these diseases. Our study reveals a predisposition to early NET formation in vitro of neutrophils obtained from patients with anti-CD20 treatment. This may contribute to associated risks of neutropenia and infections.

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.

Direct and indirect effects of pathogenic bacteria on the integrity of intestinal barrier

Bacterial translocation is a pathological process involving migration of pathogenic bacteria across the intestinal barrier to enter the systemic circulation and gain access to distant organs. This phenomenon has been linked to a diverse range of diseases including inflammatory bowel disease, pancreatitis, and cancer. The intestinal barrier is an innate structure that maintains intestinal homeostasis. Pathogenic infections and dysbiosis can disrupt the integrity of the intestinal barrier, increasing its permeability, and thereby facilitating pathogen translocation. As translocation represents an essential step in pathogenesis, a clear understanding of how barrier integrity is disrupted and how this disruption facilitates bacterial translocation could identify new routes to effective prophylaxis and therapy. In this comprehensive review, we provide an in-depth analysis of bacterial translocation and intestinal barrier function. We discuss currently understood mechanisms of bacterial-enterocyte interactions, with a focus on tight junctions and endocytosis. We also discuss the emerging concept of bidirectional communication between the intestinal microbiota and other body systems. The intestinal tract has established 'axes' with various organs. Among our regulatory systems, the nervous, immune, and endocrine systems have been shown to play pivotal roles in barrier regulation. A mechanistic understanding of intestinal barrier regulation is crucial for the development of personalized management strategies for patients with bacterial translocation-related disorders. Advancing our knowledge of barrier regulation will pave the way for future research in this field and novel clinical intervention strategies.

Assessment of Intestinal Permeability and Inflammation Bio-Markers in Patients with Rheumatoid Arthritis

Increased intestinal permeability and inflammation, both fueled by dysbiosis, appear to contribute to rheumatoid arthritis (RA) pathogenesis. This single-center pilot study aimed to investigate zonulin, a marker of intestinal permeability, and calprotectin, a marker of intestinal inflammation, measured in serum and fecal samples of RA patients using commercially available kits. We also analyzed plasma lipopolysaccharide (LPS) levels, a marker of intestinal permeability and inflammation. Furthermore, univariate, and multivariate regression analyses were carried out to determine whether or not there were associations of zonulin and calprotectin with LPS, BMI, gender, age, RA-specific parameters, fiber intake, and short-chain fatty acids in the gut. Serum zonulin levels were more likely to be abnormal with a longer disease duration and fecal zonulin levels were inversely associated with age. A strong association between fecal and serum calprotectin and between fecal calprotectin and LPS were found in males, but not in females, independent of other biomarkers, suggesting that fecal calprotectin may be a more specific biomarker than serum calprotectin is of intestinal inflammation in RA. Since this was a proof-of-principle study without a healthy control group, further research is needed to validate fecal and serum zonulin as valid biomarkers of RA in comparison with other promising biomarkers.

Therapeutic possibilities of gut microbiota modulation in acute decompensation of liver cirrhosis

The formation of liver cirrhosis (LC) is an unfavorable event in the natural history of chronic liver diseases and with the development of portal hypertension and/or impaired liver function can cause a fatal outcome. Decompensation of LC is considered the most important stratification variable for the risk of death. It is currently postulated that decompensation of LC occurs through an acute (including acute-on-chronic liver failure) and non-acute pathway. Acute decompensation of LC is accompanied by the development of life-threatening complications, characterized by an unfavorable prognosis and high mortality. Progress in understanding the underlying molecular mechanisms has led to the search for new interventions, drugs, and biological substances that can affect key links in the pathogenesis of acute decompensation in LC, for example the impaired gut-liver axis and associated systemic inflammation. Given that particular alterations in the composition and function of gut microbiota play a crucial role here, the study of the therapeutic possibilities of its modulation has emerged as one of the top concerns in modern hepatology. This review summarized the investigations that describe the theoretical foundations and therapeutic potential of gut microbiota modulation in acute decompensation of LC. Despite the encouraging preliminary data, the majority of the suggested strategies have only been tested in animal models or in preliminary clinical trials; additional multicenter randomized controlled trials must demonstrate their efficacy in larger patient populations.

Potential therapies for acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a syndrome that develops in approximately 30% of patients hospitalised with cirrhosis and is characterised by an acute decompensation of liver function associated with extra-hepatic organ failures and a high short-term mortality. At present, no specific therapies are available for ACLF, and current management is limited to treatment of the precipitating event and organ support. Given the high prevalence and high mortality of this severe liver disease, there is an urgent need for targeted treatments. There is increasing evidence of the important role played by systemic inflammation and immune dysfunction in the pathophysiology of ACLF and a better understanding of these immune processes is resulting in new therapeutic targets. The aim of this review is to present an overview of ongoing studies of potentially promising therapies and how they could be utilised in the management of ACLF.

Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials

Background

Probiotics play a vital role in treating immune and inflammatory diseases by improving intestinal barrier function; however, a comprehensive evaluation is missing. The present study aimed to explore the impact of probiotics on the intestinal barrier and related immune function, inflammation, and microbiota composition. A systematic review and meta-analyses were conducted.

Methods

Four major databases (PubMed, Science Citation Index Expanded, CENTRAL, and Embase) were thoroughly searched. Weighted mean differences were calculated for continuous outcomes with corresponding 95% confidence intervals (CIs), heterogeneity among studies was evaluated utilizing I2 statistic (Chi-Square test), and data were pooled using random effects meta-analyses.

Results

Meta-analysis of data from a total of 26 RCTs (n = 1891) indicated that probiotics significantly improved gut barrier function measured by levels of TER (MD, 5.27, 95% CI, 3.82 to 6.72, P < 0.00001), serum zonulin (SMD, -1.58, 95% CI, -2.49 to -0.66, P = 0.0007), endotoxin (SMD, -3.20, 95% CI, -5.41 to -0.98, P = 0.005), and LPS (SMD, -0.47, 95% CI, -0.85 to -0.09, P = 0.02). Furthermore, probiotic groups demonstrated better efficacy over control groups in reducing inflammatory factors, including CRP, TNF-α, and IL-6. Probiotics can also modulate the gut microbiota structure by boosting the enrichment of Bifidobacterium and Lactobacillus.

Conclusion

The present work revealed that probiotics could improve intestinal barrier function, and alleviate inflammation and microbial dysbiosis. Further high-quality RCTs are warranted to achieve a more definitive conclusion.

Clinical trial registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=281822, identifier CRD42021281822.

The shaping of gut immunity in cirrhosis

Cirrhosis is the common end-stage of chronic liver diseases of different etiology. The altered bile acids metabolism in the cirrhotic liver and the increase in the blood-brain barrier permeability, along with the progressive dysbiosis of intestinal microbiota, contribute to gut immunity changes, from compromised antimicrobial host defense to pro-inflammatory adaptive responses. In turn, these changes elicit a disruption in the epithelial and gut vascular barriers, promoting the increased access of potential pathogenic microbial antigens to portal circulation, further aggravating liver disease. After summarizing the key aspects of gut immunity during homeostasis, this review is intended to update the contribution of liver and brain metabolites in shaping the intestinal immune status and, in turn, to understand how the loss of homeostasis in the gut-associated lymphoid tissue, as present in cirrhosis, cooperates in the advanced chronic liver disease progression. Finally, several therapeutic approaches targeting the intestinal homeostasis in cirrhosis are discussed.

Biopolymer-Based Multilayer Microparticles for Probiotic Delivery to Colon

The potential health benefits of probiotics may not be realized because of the substantial reduction in their viability during food storage and gastrointestinal transit. Microencapsulation has been successfully utilized to improve the resistance of probiotics to critical conditions. Owing to the unique properties of biopolymers, they have been prevalently used for microencapsulation of probiotics. However, majority of microencapsulated products only contain a single layer of protection around probiotics, which is likely to be inferior to more sophisticated approaches. This review discusses emerging methods for the multilayer encapsulation of probiotic using biopolymers. Correlations are drawn between fabrication techniques and the resultant microparticle properties. Subsequently, multilayer microparticles are categorized based on their layer designs. Recent reports of specific biopolymeric formulations are examined regarding their physical and biological properties. In particular, animal models of gastrointestinal transit and disease are highlighted, with respect to trials of multilayer microencapsulated probiotics. To conclude, novel materials and approaches for fabrication of multilayer structures are highlighted.

Implications and Management of Cirrhosis-Associated Immune Dysfunction Before and After Liver Transplantation

Cirrhosis-associated immune dysfunction (CAID) describes a panacea of innate and adaptive deficits that result from the sequelae of cirrhotic portal hypertension that is similar in its manifestations regardless of etiology of chronic liver injury. CAID is associated with synchronous observations of dysregulated priming of innate immune effector cells that demonstrate a proinflammatory phenotype but are functionally impaired and unable to adequately prevent invading pathogens. CAID is mainly driven by gut-barrier dysfunction and is associated with deficits of microbial compartmentalization and homeostasis that lead to tonic activation, systemic inflammation, and exhaustion of innate-immune cells. CAID leads to a high frequency of bacterial and fungal infections in patients with cirrhosis that are often associated with acute decompensation of chronic liver disease and acute-on-chronic liver failure and carry a high mortality rate. Understanding the deficits of mucosal and systemic immunity in the context of chronic liver disease is essential to improving care for patients with cirrhosis, preventing precipitants of acute decompensation of cirrhosis, and improving morbidity and survival. In this review, we summarize the detailed dynamic immunological perturbations associated with advanced chronic liver disease and highlight the importance of recognizing immune dysregulation as a sequela of cirrhosis. Furthermore, we address the role of screening, prevention, and early treatment of infections in cirrhosis in improving patient outcomes in transplant and nontransplant settings.

Endotoxin Translocation and Gut Barrier Dysfunction Are Related to Variceal Bleeding in Patients With Liver Cirrhosis

Background

Bacterial infections are associated with the risk of variceal bleeding through complex pathophysiologic pathways.

Objectives

The primary objective of the present case-control study was to investigate the role of bacterial translocation and intestinal barrier dysfunction in the pathogenesis of variceal bleeding. A secondary objective was to determine independent predictors of key outcomes in variceal bleeding, including bleeding-related mortality.

Methods

Eighty-four (n = 84) consecutive patients participated in the study, 41 patients with acute variceal bleeding and 43 patients with stable cirrhosis, and were followed up for 6 weeks. Peripheral blood samples were collected at patient admission and before any therapeutic intervention.

Results

Child-Pugh (CP) score (OR: 1.868; p = 0.044), IgM anti-endotoxin antibody levels (OR: 0.954; p = 0.016) and TGF-β levels (OR: 0.377; p = 0.026) were found to be significant predictors of variceal bleeding. Regression analysis revealed that albumin (OR: 0.0311; p = 0.023), CRP (OR: 3.234; p = 0.034) and FABP2 levels (OR:1.000, p = 0.040), CP score (OR: 2.504; p = 0.016), CP creatinine score (OR: 2.366; p = 0.008), end-stage liver disease model (MELD), Na (OR: 1.283; p = 0.033), portal vein thrombosis (OR: 0.075; p = 0.008), hepatocellular carcinoma (OR: 0.060; p = 0.003) and encephalopathy (OR: 0.179; p = 0.045) were significantly associated with 6-week mortality.

Conclusions

Bacterial translocation and gut barrier impairment are directly related to the risk of variceal bleeding. Microbiota-modulating interventions and anti-endotoxin agents may be promising strategies to prevent variceal bleeding.

Lactobacillus paracasei BD5115-Derived 2-Hydroxy-3-Methylbutyric Acid Promotes Intestinal Epithelial Cells Proliferation by Upregulating the MYC Signaling Pathway

Metabolites of probiotics that are beneficial to human health have been isolated from the intestinal tract and natural dairy products. However, many studies on probiotics and prebiotics are limited to the observation of human cohorts and animal phenotypes. The molecular mechanisms by which metabolites of probiotics regulate health are still need further exploration. In this work, we isolated a strain of Lactobacillus Paracasei from human milk samples. We numbered it as Lactobacillus Paracasei BD5115. The mouse model of high-fat diet confirmed that the metabolites of this strain also promotes intestinal epithelial cells (IECs) proliferation. Single-cell sequencing showed that a bZIP transcription factor MAFF was specifically expressed in some IECs. We found that MAFF interacted with MBP1 to regulate the expression of MYC. Analysis of the active components in BD5115 metabolites confirmed that 2-hydroxy-3-methylbutyric acid promotes the expression of the MYC gene. This promotes the proliferation of IECs. Our findings indicate that 2-hydroxy-3-methylbutyric acid regulate MYC gene expression mediated by MAFF/MBP1 interaction. This study not only screened a strain with promoted IECs proliferation, but also discovered a new signal pathway that regulates MYC gene expression.

Cirrhosis-associated immune dysfunction

The term cirrhosis-associated immune dysfunction (CAID) comprises the distinctive spectrum of immune alterations associated with the course of end-stage liver disease. Systemic inflammation and immune deficiency are the key components of CAID. Their severity is highly dynamic and progressive, paralleling cirrhosis stage. CAID involves two different immune phenotypes: the low-grade systemic inflammatory phenotype and the high-grade systemic inflammatory phenotype. The low-grade systemic inflammatory phenotype can be found in patients with compensated disease or clinical decompensation with no organ failure. In this phenotype, there is an exaggerated immune activation but the effector response is not markedly compromised. The high-grade systemic inflammatory phenotype is present in patients with acute-on-chronic liver failure, a clinical situation characterized by decompensation, organ failure and high short-term mortality. Along with high-grade inflammation, this CAID phenotype includes intense immune paralysis that critically increases the risk of infections and worsens prognosis. The intensity of CAID has important consequences on cirrhosis progression and correlates with the severity of liver insufficiency, bacterial translocation and organ failure. Therapies targeting the modulation of the dysfunctional immune response are currently being evaluated in preclinical and clinical studies.

The potential role of adherence factors in probiotic function in the gastrointestinal tract of adults and pediatrics: a narrative review of experimental and human studies

Numerous studies point to the important role of probiotic bacteria in gastrointestinal health. Probiotics act through mechanisms affecting enteric pathogens, epithelial barrier function, immune signaling, and conditioning of indigenous microbiota. Once administered, probiotics reach the gastrointestinal tract and interact with the host through bacterial surface molecules, here called adhesion factors, which are either strain- or specie-specific. Probiotic adhesion, through structural adhesion factors, is a mechanism that facilitates persistence within the gastrointestinal tract and triggers the initial host responses. Thus, an understanding of specific probiotic adhesion mechanisms could predict how specific probiotic strains elicit benefits and the potential of adherence factors as a proxy to predict probiotic function. This review summarizes the present understanding of probiotic adherence in the gastrointestinal tract. It highlights the bacterial adhesion structure types, their molecular communication with the host and the consequent impact on intestinal diseases in both adult and pediatric populations. Finally, we discuss knockout/isolation studies as direct evidence for adhesion factors conferring anti-inflammatory and pathogen inhibition properties to a probiotic.What is known: Probiotics can be used to treat clinical conditions.Probiotics improve dysbiosis and symptoms.Clinical trials may not confirm in vitro and animal studies.What is new: Adhesion structures may be important for probiotic function.Need to systematically determine physical characteristics of probiotics before selecting for clinical trials.Probiotics may be genetically engineered to add to clinical efficacy.

Therapeutic potential of Saccharomyces boulardii in liver diseases: from passive bystander to protective performer?

Saccharomyces boulardii (S. boulardii) is a probiotic yeast that has been elucidated to be efficacious in fighting various gastrointestinal diseases in preclinical as well as clinical studies. Its general mechanisms of probiotic action in the treatment of gastrointestinal conditions cover multifaceted aspects, including immune regulation, production of antimicrobial substances, pathogen competitive elimination, gut barrier integrity maintenance, intestinal trophic effect and antioxidant potency. In this review, basic knowledge with regard to the gut-liver axis, available probiotics remedies and mechanistic insights of S. boulardii as probiotics will be elucidated. In addition, we summarize the therapeutic potential of S. boulardii in several liver diseases evident from both bench and bedside information, such as acute liver injury/failure, fibrosis, hepatic damages due to metabolic disturbance or infection and obstructive jaundice. Future prospects in relation to medicinal effects of S. boulardii are also exploited and discussed on the basis of novel and attractive therapeutic concept in the latest scientific literature.

Microbiome therapeutics for hepatic encephalopathy

Hepatic encephalopathy (HE) is a complication of cirrhosis characterised by neuropsychiatric and motor dysfunction. Microbiota-host interactions play an important role in HE pathogenesis. Therapies targeting microbial community composition and function have been explored for the treatment of HE. Prebiotics, probiotics and faecal microbiota transplant (FMT) have been used with the aim of increasing the abundance of potentially beneficial taxa, while antibiotics have been used to decrease the abundance of potentially harmful taxa. Other microbiome therapeutics, including postbiotics and absorbents, have been used to target microbial products. Microbiome-targeted therapies for HE have had some success, notably lactulose and rifaximin, with probiotics and FMT also showing promise. However, there remain several challenges to the effective application of microbiome therapeutics in HE, including the resilience of the microbiome to sustainable change and unpredictable clinical outcomes from microbiota alterations. Future work in this space should focus on rigorous trial design, microbiome therapy selection, and a personalised approach to HE.

Influence of Probiotics Administration Before Liver Resection in Patients with Liver Disease: A Randomized Controlled Trial

BACKGROUND

By inhibiting the growth of pathogenic bacteria and modulating the local intestinal immune system, probiotics may reduce bacterial translocation and systemic endotoxaemia, factors partially responsible for post-operative complications following liver resection for hepatocellular carcinoma in patients with cirrhosis.

METHODS

Patients with resectable hepatocellular carcinoma developed in the setting of chronic liver disease were prospectively divided into two equal-sized groups: one receiving probiotic treatment 14 days prior to surgery and the other receiving placebo. The primary endpoint was the level of circulating endotoxins after hepatectomy. Secondary endpoints were systemic inflammation (inflammatory cytokine levels), post-operative liver function and overall post-operative complication rate.

RESULTS

From May 2013 to December 2018, 64 patients were randomized, and 54 patients were included in the analysis, 27 in each arm. No significant change in endotoxin levels was observed over time in either group (P = 0.299). No difference between the groups in terms of post-operative liver function and overall complication rates was observed. The only differences observed were significant increases in the levels of TNFalpha (P = 0.019) and interleukin 1-b (P = 0.028) in the probiotic group in the post-operative period.

CONCLUSION

Contrary to the modest data reported in the literature, the administration of probiotics before minor liver resection for hepatocellular carcinoma developed in the setting of compensated chronic liver disease does not seem to have an impact on circulating endotoxin levels or post-operative complication rates.

TRIAL REGISTRATION

Trial registration: NCT02021253.

Kefir Is a Viable Exercise Recovery Beverage for Cancer Survivors Enrolled in a Structured Exercise Program

PURPOSE

This study investigated the effects of 12 wk of postexercise kefir consumption in cancer survivors who have undergone chemotherapy and/or radiation therapy.

METHODS

All participants were enrolled in a structured exercise training program and separated into kefir (KEF) or control (CON) treatment groups. KEF consumed 8 oz. of kefir after exercise sessions (3 d·wk-1) for 12 wk. Outcome measures included assessments for body size and composition, aerobic fitness and muscular strength, medical history, and psychological state at pre- and postintervention time points. Blood was collected and analyzed for C-reactive protein (CRP), interleukin 6 (IL-6), and lipopolysaccharide (LPS) concentrations, and LPS-stimulated whole blood IL-6 and tumor necrosis factor α production were obtained using enzyme-linked immunosorbent assays at both time points. Monocyte numbers and phenotype were obtained using flow cytometry.

RESULTS

Participants (N = 24; 9 males and 15 females) were an average of 61 ± 9.9 yr old. Kefir consumption was associated with 6.3% (P = 0.034) improvements in lean body mass, as well as 51.4% (P = 0.046), 39.3% (P = 0.017), and 64.7% (P = 0.021) improvements in measures of depression, fatigue, and gastric distress, respectively. KEF also experienced a significant 35.4% (P = 0.01) reduction in circulating LPS along with an 18.0% increase (P < 0.001) in classical monocytes % and a 22.3% decrease (P = 0.04) in nonclassical monocytes %. There were no significant changes in any other variables.

CONCLUSION

Twelve weeks of kefir consumption improved lean body mass, depression, fatigue, gastric distress, and a biomarker of gut dysbiosis. Kefir improved overall and classical monocyte numbers. Kefir should be considered as a component of a postexercise dietary regimen for cancer survivors.

Probiotics in hepatology: An update

The gut–liver axis plays an important role in the pathogenesis of various liver diseases. Probiotics are living bacteria that may be used to correct disorders of this axis. Notable progress has been made in the study of probiotic drugs for the treatment of various liver diseases in the last decade. It has been proven that probiotics are useful for hepatic encephalopathy, but their effects on other symptoms and syndromes of cirrhosis are poorly studied. Their effectiveness in the treatment of metabolic associated fatty liver disease has been shown both in experimental models and in clinical trials, but their effect on the prognosis of this disease has not been described. The beneficial effects of probiotics in alcoholic liver disease have been shown in many experimental studies, but there are very few clinical trials to support these findings. The effects of probiotics on the course of other liver diseases are either poorly studied (such as primary sclerosing cholangitis, chronic hepatitis B and C, and autoimmune hepatitis) or not studied at all (such as primary biliary cholangitis, hepatitis A and E, Wilson's disease, hemochromatosis, storage diseases, and vascular liver diseases). Thus, despite the progress in the study of probiotics in hepatology over the past decade, there are many unexplored and unclear questions surrounding this topic.

Alcohol's Impact on the Gut and Liver

Alcohol is inextricably linked with the digestive system. It is absorbed through the gut and metabolised by hepatocytes within the liver. Excessive alcohol use results in alterations to the gut microbiome and gut epithelial integrity. It contributes to important micronutrient deficiencies including short-chain fatty acids and trace elements that can influence immune function and lead to liver damage. In some people, long-term alcohol misuse results in liver disease progressing from fatty liver to cirrhosis and hepatocellular carcinoma, and results in over half of all deaths from chronic liver disease, over half a million globally per year. In this review, we will describe the effect of alcohol on the gut, the gut microbiome and liver function and structure, with a specific focus on micronutrients and areas for future research.

Potential probiotic Lacticaseibacillus rhamnosus MTCC-5897 attenuates Escherichia coli induced inflammatory response in intestinal cells

Probiotics are microbes having tremendous potential to prevent gastrointestinal disorders. In current investigation, immunomodulatory action of probiotic Lacticaseibacillus rhamnosus MTCC-5897 was studied during exclusion, competition and displacement of Escherichia coli on intestinal epithelial (Caco-2) cells. The incubation of intestinal cells with Escherichia coli, enhanced downstream signalling and activated nuclear factor kappa B (NF-κB). This significantly increased (p < 0.01) the pro-inflammatory cytokines (IL-8, TNF-α, IFN-ϒ) expression. While, incubation of epithelial cells with Lacticaseibacillus rhamnosus during exclusion and competition with Escherichia coli, counteracted these enhanced expressions. The immunomodulatory feature of Lacticaseibacillus rhamnosus was also highlighted with increased (p < 0.05) transcription of toll-like receptor-2 (TLR-2) and single Ig IL-1-related receptor (SIGIRR) along with diminished expression of TLR-4. Likewise, attenuation (p < 0.05) of E. coli-mediated enhanced nuclear translocation of NF-κB p-65 subunit by Lacticaseibacillus rhamnosus during exclusion was confirmed with western blotting. Thus, present finding establishes the prophylactic potential of Lacticaseibacillus rhamnosus against exclusion of Escherichia coli in intestinal cells.

Direct acting antiviral therapy rescues neutrophil dysfunction and reduces hemolysis in hepatitis C infection

Chronic hepatitis C virus infection is characterized by multiple extra-hepatic manifestations. Innate immune dysfunction and hemolysis are symptoms which might be associated with each other. We investigated the impact of direct acting antivirals on neutrophil function and its connection to hemolysis. In this prospective study, 85 patients with or without cirrhosis and 21 healthy controls were included. Patients' blood samples were taken at baseline, at the end of therapy and at follow-up 12 weeks after end of therapy. Neutrophil phagocytosis, oxidative burst, and hemolysis parameters were studied. Multivariate analysis was performed to decipher the relationship between hemolysis and neutrophil function. Ex vivo cross-incubation experiments with neutrophils and serum fractions were done. Impaired neutrophil phagocytosis and mild hemolysis were observed in patients with and without cirrhosis. A proteome approach revealed different expression of hemolysis-related serum proteins in patients and controls. Direct acting antiviral therapy restored neutrophil function irrespective of severity of liver disease, achievement of sustained virologic response or type of drug and reduced hemolysis. Treatment with ribavirin delayed the improvement of neutrophil function. Statistical analysis revealed associations of haptoglobin with neutrophil phagocytic capacity. Neutrophil dysfunction could be transferred to healthy cells by incubation with patients' serum fractions (>30 kDa) ex vivo. Neutrophil dysfunction and hemolysis represent extrahepatic manifestations of chronic hepatitis C virus infection and simultaneously improve during direct acting antiviral therapy independently of therapy-related liver function recovery. Therefore, large-scale treatment would not only drive viral eradication but also improve patients' immune system and may reduce susceptibility to infections.

Nonalcoholic Fatty Liver Disease: Focus on New Biomarkers and Lifestyle Interventions

Nonalcoholic fatty liver disease (NAFLD) is considered a hepatic manifestation of metabolic syndrome, characterized from pathological changes in lipid and carbohydrate metabolism. Its main characteristics are excessive lipid accumulation and oxidative stress, which create a lipotoxic environment in hepatocytes leading to liver injury. Recently, many studies have focused on the identification of the genetic and epigenetic modifications that also contribute to NAFLD pathogenesis and their prognostic implications. The present review is aimed to discuss on cellular and metabolic alterations associated with NAFLD, which can be helpful to identify new noninvasive biomarkers. The identification of accumulated lipids in the cell membranes, as well as circulating cytokeratins and exosomes, provides new insights in understanding of NAFLD. This review also suggests that lifestyle modifications remain the main prevention and/or treatment for NAFLD.

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.

The Gut-Liver Axis in Cholestatic Liver Diseases

The gut-liver axis describes the physiological interplay between the gut and the liver and has important implications for the maintenance of health. Disruptions of this equilibrium are an important factor in the evolution and progression of many liver diseases. The composition of the gut microbiome, the gut barrier, bacterial translocation, and bile acid metabolism are the key features of this cycle. Chronic cholestatic liver diseases include primary sclerosing cholangitis, the generic term secondary sclerosing cholangitis implying the disease secondary sclerosing cholangitis in critically ill patients and primary biliary cirrhosis. Pathophysiology of these diseases is not fully understood but seems to be multifactorial. Knowledge about the alterations of the gut-liver axis influencing the pathogenesis and the outcome of these diseases has considerably increased. Therefore, this review aims to describe the function of the healthy gut-liver axis and to sum up the pathological changes in these cholestatic liver diseases. The review compromises the actual level of knowledge about the gut microbiome (including the mycobiome and the virome), the gut barrier and the consequences of increased gut permeability, the effects of bacterial translocation, and the influence of bile acid composition and pool size in chronic cholestatic liver diseases. Furthermore, therapeutic implications and future scientific objectives are outlined.

The Role of Intestinal Bacteria and Gut-Brain Axis in Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a neurological disorder that occurs in patients with liver insufficiency. However, its pathogenesis has not been fully elucidated. Pharmacotherapy is the main therapeutic option for HE. It targets the pathogenesis of HE by reducing ammonia levels, improving neurotransmitter signal transduction, and modulating intestinal microbiota. Compared to healthy individuals, the intestinal microbiota of patients with liver disease is significantly different and is associated with the occurrence of HE. Moreover, intestinal microbiota is closely associated with multiple links in the pathogenesis of HE, including the theory of ammonia intoxication, bile acid circulation, GABA-ergic tone hypothesis, and neuroinflammation, which contribute to cognitive and motor disorders in patients. Restoring the homeostasis of intestinal bacteria or providing specific probiotics has significant effects on neurological disorders in HE. Therefore, this review aims at elucidating the potential microbial mechanisms and metabolic effects in the progression of HE through the gut–brain axis and its potential role as a therapeutic target in HE.

Post-hoc analysis of a randomized controlled trial on the impact of pre-transplant use of probiotics on outcomes after liver transplantation

Perioperative use of probiotics serves as efficient prophylaxis against postoperative infections after liver transplantation, yet data on long-term effects of pre-transplant probiotic intake is lacking. The aim of this study was to assess the effects of pre-transplant probiotic administration on long-term results of liver transplantation. This was secondary analysis of a randomized trial. Patients were randomized to receive either 4-strain probiotic or placebo before liver transplantation. Five year graft survival was set as the primary end-point. Secondary end-points comprised serum bilirubin and C-reactive protein (CRP) concentration, international normalized ratio (INR), serum transaminases and gamma-glutamyl transferase (GGT) activity. Study group comprised 44 patients, of whom 21 received probiotics and 23 received placebo with 5-year graft survival of 81.0% and 87.0%, respectively (p = 0.591). Patients in the probiotic arm exhibited lower INR (p = 0.001) and CRP (p = 0.030) over the first 6 post-transplant months. In the absence of hepatitis B or C virus infection, pre-transplant administration of probiotics also reduced aspartate transaminase activity (p = 0.032). In the intervention arm, patients receiving probiotics for under and over 30 days had 5-year graft survival rates of 100% and 66.7%, respectively (p = 0.061). Duration of probiotic intake > 30 days was additionally associated with increased INR (p = 0.031), GGT (p = 0.032) and a tendency towards increased bilirubin (p = 0.074) over first 6 post-transplant months. Pre-transplant administration of probiotics has mild positive influence on 6-month allograft function, yet should not exceed 30 days due to potential negative effects on long-term outcomes. (ClinicalTrials.gov Identifier: NCT01735591).

Tryptophan Metabolism and Related Pathways in Psychoneuroimmunology: The Impact of Nutrition and Lifestyle

In the past, accelerated tryptophan breakdown was considered to be a feature of clinical conditions, such as infection, inflammation, and malignant disease. More recently, however, the focus has changed to include the additional modulation of tryptophan metabolism by changes in nutrition and microbiota composition. The regulation of tryptophan concentration is critical for the maintenance of systemic homeostasis because it integrates essential pathways involved in nutrient sensing, metabolic stress response, and immunity. In addition to tryptophan being important as a precursor for the synthesis of the neurotransmitter serotonin, several catabolites along the kynurenine axis are neuroactive. This emphasizes the importance of the immunometabolic fate of this amino acid for processes relevant to neuropsychiatric symptoms. In humans, besides hepatic catabolism, there is usually a strong relationship between immune activation-associated tryptophan breakdown and increased levels of biomarkers, such as neopterin, which has particular relevance for both acute and chronic diseases. A shift towards neopterin synthesis during oxidative stress may indicate a corresponding decrease in tetrahydrobiopterin, a cofactor of several mono-oxygenases, providing a further link between tryptophan metabolism and serotonergic and catecholaminergic neurotransmission. The psychoneuroimmunological consequences of tryptophan metabolism and the susceptibility of this pathway to modulation by a variety of nutritional and lifestyle-related factors have important implications for the development of both diagnostic and treatment options.

The Gut Barrier, Intestinal Microbiota, and Liver Disease: Molecular Mechanisms and Strategies to Manage

Liver disease encompasses pathologies as non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, alcohol liver disease, hepatocellular carcinoma, viral hepatitis, and autoimmune hepatitis. Nowadays, underlying mechanisms associating gut permeability and liver disease development are not well understood, although evidence points to the involvement of intestinal microbiota and their metabolites. Animal studies have shown alterations in Toll-like receptor signaling related to the leaky gut syndrome by the action of bacterial lipopolysaccharide. In humans, modifications of the intestinal microbiota in intestinal permeability have also been related to liver disease. Some of these changes were observed in bacterial species belonging Roseburia, Streptococcus, and Rothia. Currently, numerous strategies to treat liver disease are being assessed. This review summarizes and discusses studies addressed to determine mechanisms associated with the microbiota able to alter the intestinal barrier complementing the progress and advancement of liver disease, as well as the main strategies under development to manage these pathologies. We highlight those approaches that have shown improvement in intestinal microbiota and barrier function, namely lifestyle changes (diet and physical activity) and probiotics intervention. Nevertheless, knowledge about how such modifications are beneficial is still limited and specific mechanisms involved are not clear. Thus, further in-vitro, animal, and human studies are needed.

Secondary Sclerosing Cholangitis in Critically Ill Patients Alters the Gut-Liver Axis: A Case Control Study

Secondary sclerosing cholangitis in critically ill patients (SC-CIP) occurs after long-term intensive care treatment. This study aimed to assess the gut-liver axis in SC-CIP. Stool microbiome composition, gut permeability, bacterial translocation and serum bile acid profiles of 18 SC-CIP patients compared to 11 patients after critical illness without liver disease (CIP controls), 21 patients with cirrhosis and 21 healthy controls were studied. 16S rDNA was isolated from stool and sequenced using the Illumina technique. Diamine oxidase, zonulin, soluble CD14 (sCD14) and lipopolysaccharide binding protein were measured in serum and calprotectin in stool. Serum bile acids were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Reduced microbiome alpha diversity and altered beta diversity were seen in SC-CIP, CIP controls and cirrhosis compared to healthy controls. SC-CIP patients showed a shift towards pathogenic taxa and an oralization. SC-CIP, CIP controls and cirrhotic patients presented with impaired gut permeability, and biomarkers of bacterial translocation were increased in SC-CIP and cirrhosis. Total serum bile acids were elevated in SC-CIP and cirrhosis and the bile acid profile was altered in SC-CIP, CIP controls and cirrhosis. In conclusions, observed alterations of the gut-liver axis in SC-CIP cannot solely be attributed to liver disease, but may also be secondary to long-term intensive care treatment.

The Development of High-Quality Multispecies Probiotic Formulations: From Bench to Market

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. To date, there is an increasing number of commercially available products containing probiotics on the market. Probiotics have been recommended by health care professionals for reasons ranging from their long-term immunomodulatory effects to proven benefits in the management of different health conditions. For probiotic products, there are several important aspects that determine the success rate of the development from bench to market. The aim of this review is to explore how the current knowledge on microbe–microbe and host–microbe interactions can be used to develop high-quality, evidence-based probiotic formulations, specifically probiotic dietary supplements, with a focus on the selection of safe strains with relevant functional properties. In addition, we will highlight aspects of the probiotic manufacturing process that need to be considered during the product development and the subsequent manufacturing process to guarantee consistent efficacy of a probiotic product. For each high-quality probiotic formulation, it is important to screen multiple strains, and select only those strains that show relevant functional properties and that can be considered safe for human consumption. In addition, it is imperative that attention is paid to the product development and manufacturing process, and that safety and quality properties are monitored. Importantly, the beneficial effects of probiotics should be evaluated in product efficacy studies and post-marketing surveys in order to demonstrate their clinical efficacy. All these aspects need to be evaluated and validated during the development of a successful high-quality and ready-to-market probiotic.

Effects of both Pro- and Synbiotics in Liver Surgery and Transplantation with Special Focus on the Gut-Liver Axis-A Systematic Review and Meta-Analysis

The gut-liver axis is of upmost importance for the development of infections after surgery. Further bacterial translocation due to surgery-related dysbiosis is associated with limited detoxification function of the liver compromising outcome of surgical therapy. After liver surgery, about 30% of patients develop a bacterial infection, with the risk of bacteremia or even sepsis-associated liver failure and mortality in >40%. The potential benefit of pro-/synbiotics given before surgery is still under debate. Thus, a systematic literature search on trials comparing patients with or without supplementation and outcome after liver resection or transplantation was performed. Our search strategy revealed 12 relevant studies on perioperative administration of pro-/synbiotics in liver surgery. The pro-/synbiotic combinations and concentrations as well as administration timeframes differed between studies. Five studies were performed in liver transplantation and 7 in liver resection. All studies but one reported lower infection rates (pooled RR: 0.46, 95% CI: 0.31–0.67) with pro-/synbiotics. Liver function was assessed after LT/LR in 3 and 5 studies, respectively. Pro-/synbiotics improved function in 1/3 and 2/5 studies, respectively. Concluding, perioperative pro-/synbiotics clearly reduce infection after liver surgery. However, standard protocols with both well-defined probiotic strain preparations and administration timeframes are pending.

Liver Cirrhosis and Sarcopenia from the Viewpoint of Dysbiosis

Sarcopenia in patients with liver cirrhosis (LC) has been attracting much attention these days because of the close linkage to adverse outcomes. LC can be related to secondary sarcopenia due to protein metabolic disorders and energy metabolic disorders. LC is associated with profound alterations in gut microbiota and injuries at the different levels of defensive mechanisms of the intestinal barrier. Dysbiosis refers to a state in which the diversity of gut microbiota is decreased by decreasing the bacterial species and the number of bacteria that compose the gut microbiota. The severe disturbance of intestinal barrier in LC can result in dysbiosis, several bacterial infections, LC-related complications, and sarcopenia. Here in this review, we will summarize the current knowledge of the relationship between sarcopenia and dysbiosis in patients with LC.

Dysbiosis, gut barrier dysfunction and inflammation in dementia: a pilot study

BACKGROUND

Dementia is an increasing public health threat worldwide. The pathogenesis of dementia has not been fully elucidated yet. Inflammatory processes are hypothesized to play an important role as a driver for cognitive decline but the origin of inflammation is not clear. We hypothesize that disturbances in gut microbiome composition, gut barrier dysfunction, bacterial translocation and resulting inflammation are associated with cognitive dysfunction in dementia.

METHODS

To test this hypothesis, a cohort of 23 patients with dementia and 18 age and sex matched controls without cognitive impairments were studied. Gut microbiome composition, gut barrier dysfunction, bacterial translocation and inflammation were assessed from stool and serum samples. Malnutrition was assessed by Mini Nutritional Assessment Short Form (MNA-SF), detailed information on drug use was collected. Microbiome composition was assessed by 16S rRNA sequencing, QIIME 2 and Calypso 7.14 tools.

RESULTS

Dementia was associated with dysbiosis characterized by differences in beta diversity and changes in taxonomic composition. Gut permeability was increased as evidenced by increased serum diamine oxidase (DAO) levels and systemic inflammation was confirmed by increased soluble cluster of differentiation 14 levels (sCD14). BMI and statin use had the strongest impact on microbiome composition.

CONCLUSION

Dementia is associated with changes in gut microbiome composition and increased biomarkers of gut permeability and inflammation. Lachnospiraceae NK4A136 group as potential butyrate producer was reduced in dementia. Malnutrition and drug intake were factors, that impact on microbiome composition. Increasing butyrate producing bacteria and targeting malnutrition may be promising therapeutic targets in dementia.

TRIAL REGISTRATION

NCT03167983 .

The Effects of Probiotic/Synbiotic on Serum Level of Zonulin as a Biomarker of Intestinal Permeability: A Systematic Review and Meta-Analysis

Background:

This systematic review and meta-analysis was conducted to obtain a conclusive result on the influence of probiotics/synbiotic on serum levels of zonulin. Data related to serum levels of zonulin were extracted to determine the effects of probiotic/synbiotic on intestinal permeability.

Methods:

The literature search was conducted across the Cochrane Central Register of Controlled Trials, Pub-Med, Scopus and ISI Web of Science, Search up to Nov 2018. Clinical trials evaluating the effect of probiotic/synbiotic on serum zonulin levels of all human subjects were included.

Results:

Nine studies (including 496 intervention and 443 control subjects) met the inclusion criteria for the meta-analysis. According to the meta-analysis, probiotic/synbiotic has a significant effect on serum zonulin reduction (WMD=−10.55 [95% CI: −17.76, −3.34]; P=0.004). However, the high level of heterogeneity was observed among the studies (I²=97.8, P<0.001). The subgroup analysis suggested study quality, blinding, study duration, Participants age, subject’s health status and supplement type as sources of heterogeneity.

Conclusion:

Probiotic/synbiotic have favorable effects on serum levels of zonulin as a measure of intestinal permeability. However, the results should be interpreted with caution due to the high heterogeneity and further evidence is required before definitive recommendations can be made.

Changes in the Intestinal Microbiome during a Multispecies Probiotic Intervention in Compensated Cirrhosis

Probiotics have been used in trials to therapeutically modulate the gut microbiome and have shown beneficial effects in cirrhosis. However, their effect on the microbiome of cirrhosis patients is not fully understood yet. Here, we tested the effects of a multispecies probiotic on microbiome composition in compensated cirrhosis. The gut microbiome composition of 58 patients with compensated cirrhosis from a randomized controlled trial who received a daily dose of multispecies probiotics or placebo for six months was analysed by 16S rRNA gene sequencing. Microbiome composition of patients who received probiotics was enriched with probiotic strains and the abundance of Faecalibacterium prausnitzii, Syntrophococcus sucromutans, Bacteroides vulgatus, Alistipes shahii and a Prevotella species was increased in the probiotic group compared to the placebo group. Patients who had microbiome changes in response to probiotic treatment also showed a significant increase in neopterin and a significant decrease in faecal zonulin levels after intervention, which was not observed in placebo-treated patients or patients with unchanged microbiome compositions. In conclusion, multispecies probiotics may enrich the microbiome of compensated cirrhotic patients with probiotic bacteria during a six-month intervention and beneficially change the residential microbiome and gut barrier function.

A Double-Blind, Randomized Placebo-Controlled Trial of Probiotic Lactobacillus casei Shirota in Stable Cirrhotic Patients

Background: In cirrhosis, a pathological gut microbiome has been linked with immune dysfunction. A pilot study of probiotic Lactobacillus casei Shirota (LcS) in alcoholic cirrhosis demonstrated significant improvement in neutrophil function. This study aimed to evaluate the efficacy of LcS on neutrophil function and significant infection rates in patients with cirrhosis. Methods: 92 cirrhotic patients (Child-Pugh score ≤10) were randomized to receive LcS or placebo, three times daily for six months. Primary end-points were incidence of significant infection and neutrophil function. Secondary end-points were cytokine profile, endotoxin, bacterial DNA positivity, intestinal permeability and quality of life. Results: Rates of infection, decompensation or neutrophil function did not differ between placebo and probiotic groups. LcS significantly reduced plasma monocyte chemotactic protein-1 and, on subgroup analysis, plasma interleukin-1β (alcoholic cirrhosis), interleukin-17a and macrophage inflammatory protein-1β (non-alcoholic cirrhosis), compared with placebo. No significant differences in intestinal permeability, bacterial translocation or metabolomic profile were observed. Conclusion: LcS supplementation in patients with early cirrhosis is safe. Although no significant infections were observed in either group, LcS improved cytokine profile towards an anti-inflammatory phenotype, an effect which appears to be independent of bacterial translocation.