Intestinal permeability in a patient with liver cirrhosis

Non-O1/non-O139 Vibrio cholerae bacteremia and hepatitis in diabetic patient, France, winter 2019

OBJECTIVES

Vibrio cholerae non-O1/non-O139 (NOVC) bacteremia is infrequently reported in Western countries and is associated with unfavorable outcome.

PATIENT/METHOD

We describe here the case of a diabetic patient with hepatic cytolysis and NOVC bacteremia following an episode of diarrhea.

RESULT

The patient was paucisymptomatic and had a favorable resolution with oral ciprofloxacin.

CONCLUSION

NOVC should be systematically sought in stool samples, particularly in immunocompromised patients, due to an increased risk of infection occurrence.

Fabrication of a decellularized liver matrix-based hepatic patch for the repair of CCl4-induced liver injury

This article primarily introduces a new treatment for liver fibrosis/cirrhosis. We developed a hepatic patch by combining decellularized liver matrix (DLM) with the hepatocyte growth factor (HGF)/heparin-complex and evaluated its restorative efficacy. In vitro prophylactic results, the HGF/heparin-DLM patches effectively mitigated CCl4-induced hepatocyte toxicity and restored the cytotoxicity levels to the baseline levels by day 5. Furthermore, these patches restored albumin synthesis of injured hepatocytes to more than 70% of the normal levels within 5 days. In vitro therapeutic results, the urea synthesis of the injured hepatocytes reached 91% of the normal levels after 10 days of culture, indicating successful restoration of hepatic function by the HGF/heparin-DLM patches in both prophylactic and therapeutic models. In vivo results, HGF/heparin-DLM patches attached to the liver and gut exhibited a significant decrease in collagen content (4.44 times and 2.77 times, respectively) and an increase in glycogen content (1.19 times and 1.12 times, respectively) compared to the fibrosis group after 1 week, separately. In summary, liver function was restored and inflammation was inhibited through the combined effects of DLM and the HGF/heparin-complex in fibrotic liver. The newly designed hepatic patch holds promise for both in vitro and in vivo regeneration therapy and preventive health care for liver tissue engineering.

Role of inflammasomes and cytokines in immune dysfunction of liver cirrhosis

Liver cirrhosis develops as a result of persistent inflammation and liver injury. The prolonged inflammation triggers the buildup of fibrous tissue and regenerative nodules within the liver, leading to the distortion of the hepatic vascular structure and impaired liver function. Cirrhosis disrupts the ability of liver function to maintain homeostasis and hepatic immunosurveillance which causes immunological dysfunction in the body. In pathological conditions, the production of cytokines in the liver is carefully regulated by various cells in response to tissue stimulation. Cytokines and inflammasomes are the key regulators and systematically contribute to the development of cirrhosis which involves an inflammatory response. However, the crosstalk role of different cytokines in the cirrhosis progression is poorly understood. Tumour necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), and interferon-gamma (IFN-γ), among others, are proinflammatory cytokines that contribute to liver cell necrosis, which in turn causes the development of fibrosis. While IL-10 exhibits a potent anti-inflammatory effect on the liver by inhibiting immune cell activation and neutralizing pro-inflammatory cytokine activity. Inflammasomes have also been implicated in the profibrotic processes of liver cirrhosis, as well as the production of chemokines such as CCL2/MCP-1. It is evident that inflammasomes have a role in the proinflammatory response seen in chronic liver illnesses. In conclusion, cirrhosis significantly impacts the immune system, leading to immunological dysfunction and alterations in both innate and acquired immunity. Proinflammatory cytokines like TNF-α, IL-1β, IL-6, and IFNγ are upregulated in cirrhosis, contributing to liver cell necrosis and fibrosis development. Managing cytokine-mediated inflammation and fibrosis is a key therapeutic approach to alleviate portal hypertension and its associated liver complications. This review attempted to focus largely on the role of immune dysfunction mediated by different cytokines and inflammasomes involved in the progression, regulation and development of liver cirrhosis.

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.

Effects of Isosakuranetin on Pharmacokinetic Changes of Tofacitinib in Rats with N-Dimethylnitrosamine-Induced Liver Cirrhosis

Tofacitinib, a Janus kinase 1 and 3 inhibitor, is used to treat rheumatoid arthritis. It is mainly metabolized by the cytochromes p450 (CYP) 3A1/2 and CYP2C11 in the liver. Chronic inflammation eventually leads to cirrhosis in patients with rheumatoid arthritis. Isosakuranetin (ISN), a component of Citrus aurantium L., has hepatoprotective effects in rats. This study was performed to determine the effects of ISN on the pharmacokinetics of tofacitinib in rats with N-dimethylnitrosamine-induced liver cirrhosis (LC). After intravenous administration of 10 mg/kg tofacitinib to control (CON), LC, and LC treated with ISN (LC-ISN) rats, the total area under the plasma concentration-time curves (AUC) from time zero to infinity increased by 158% in LC rats compared to those in CON rats; however, the AUC of LC-ISN rats decreased by 35.1% compared to that of LC rat. Similar patterns of AUC changes were observed in the LC and LC-ISN rats after oral administration of 20 mg/kg tofacitinib. These results can be attributed to decreased non-renal clearance (CL_NR) and intestinal intrinsic clearance (CL_int) in the LC rats and increased intestinal and hepatic CL_int in the LC-ISN rats. Our findings imply that ISN treatment in LC rats restored the decrease in either CL_NR or CL_int, or both, through increased hepatic and intestinal expression of CYP3A1/2 and CYP2C11, which is regulated by the induction of pregnane X receptor (PXR) and constitutive androstane receptor (CAR).

Periplanetaamericana Extract Pretreatment Alleviates Oxidative Stress and Inflammation and Increases the Abundance of Gut Akkermansia muciniphila in Diquat-Induced Mice

Studies have shown that Periplaneta americana extract (PAE) has good therapeutic effects in inflammatory disorders such as ulcerative colitis, alcoholic hepatitis, and gastric ulcers. However, whether or not PAE has good pre-protective effects has not been widely and deeply studied. In this study, we investigated the effects of PAE pretreatment for 7 days on oxidative stress and inflammation triggered by oxidative stress by using diquat-induced C57BL/6 mice as an oxidative stress model. The results showed that PAE pretreatment could significantly reduce oxidative stress in the intestine and liver by reducing the production of MDA, and improved antioxidant systems (SOD, CAT, GSH, and T-AOC). By primarily activating the anti-inflammatory cytokine (IL-10) mediated JAK1/STAT3 signaling pathway, PAE also effectively reduced oxidative stress-induced liver inflammation while also reducing liver damage, as evidenced by the reductions in serum AST and ALT. PAE pretreatment also had a significant effect on maintaining the intestinal barrier function, which was manifested by inhibiting a decrease in the expression of tight junction proteins (ZO-1 and occludin), and reducing the increased intestinal permeability (serum DAO and D-Lac) caused by diquat. The 16S rRNA sequencing analysis revealed that diquat decreased the gut microbiota diversity index and increased the abundance of pathogenic bacteria (e.g., Allobaculum, Providencia and Escherichia-Shigella), while PAE pretreatment responded to diquat-induced damage by greatly increasing the abundance of Akkermansia muciniphila. These findings elucidate potential pre-protective mechanisms of PAE in alleviating oxidative stress and inflammation, while providing a direction for the treatment of metabolic diseases by utilizing PAE to enhance the abundance of gut A. muciniphila.

Transjugular intrahepatic porto-systemic shunt in cirrhotic patients with hepatorenal syndrome - chronic kidney disease: Impact on renal function

BACKGROUND AND AIMS

Transjugular intrahepatic porto-systemic shunt (TIPS) ameliorates renal function in type-2 hepatorenal syndrome (HRS). Available evidence is based on 'old' HRS diagnostic criteria, and not on the current definition of HRS - chronic kidney disease (HRS-CKD). Among patients who underwent TIPS for refractory ascites over the last 12 years, we investigated clinical and renal function evolution of those with HRS-CKD.

METHODS

among 212 patients, 41 with HRS-CKD were included. Renal function was evaluated for 12 months after TIPS, along with management of ascites and transplant-free survival (TFS).

RESULTS

renal function significantly improved already one week after TIPS [serum creatinine (sCr): 1.37 ± 0.23 vs 1.94 ± 0.54 mg/dl, p< 0.001]; the amelioration was maintained during the whole follow-up and was observed in every CKD stage, defined according to baseline estimated Glomerular Filtration Rate (eGFR). sCr and eGFR became comparable between different CKD stages after only one week, whilst significantly different at baseline. TIPS led to a remarkable improvement in the control of ascites in all CKD stages and no significant differences in TFS were recorded.

CONCLUSIONS

TIPS led to an early, substantial and persistent improvement in renal function in patients with HRS-CKD, irrespective of their baseline CKD stage.

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.

The Gut-Liver Axis in Chronic Liver Disease: A Macrophage Perspective

Chronic liver disease (CLD) is a growing health concern which accounts for two million deaths per year. Obesity, alcohol overconsumption, and progressive cholestasis are commonly characterized by persistent low-grade inflammation and advancing fibrosis, which form the basis for development of end-stage liver disease complications, including hepatocellular carcinoma. CLD pathophysiology extends to the intestinal tract and is characterized by intestinal dysbiosis, bile acid dysregulation, and gut barrier disruption. In addition, macrophages are key players in CLD progression and intestinal barrier breakdown. Emerging studies are unveiling macrophage heterogeneity and driving factors of their plasticity in health and disease. To date, in-depth investigation of how gut-liver axis disruption impacts the hepatic and intestinal macrophage pool in CLD pathogenesis is scarce. In this review, we give an overview of the role of intestinal and hepatic macrophages in homeostasis and gut-liver axis disruption in progressive stages of CLD.

A bridge for short-chain fatty acids to affect inflammatory bowel disease, type 1 diabetes, and non-alcoholic fatty liver disease positively: by changing gut barrier

PURPOSE

In previous studies, short-chain fatty acids (SCFAs) have been found to regulate gut microbiota and change gut barrier status, and the potential positive effects of SCFAs on inflammatory bowel disease (IBD), type 1 diabetes mellitus (T1D), and non-alcoholic fatty liver disease (NAFLD) have also been found, but the role of SCFAs in these three diseases is not clear. This review aims to summarize existing evidence on the effects of SCFAs on IBD, T1D, and NHFLD, and correlates them with gut barrier and gut microbiota (gut microbiota barrier).

METHODS

A literature search in PubMed, Web of Science, Springer, and Wiley Online Library up to October 2020 was conducted for all relevant studies published.

RESULTS

This is a retrospective review of 150 applied research articles or reviews. The destruction of gut barrier may promote the development of IBD, T1D, and NAFLD. SCFAs seem to maintain the gut barrier by promoting the growth of intestinal epithelial cells, strengthening the intestinal tight connection, and regulating the activities of gut microbiota and immune cells, which might result possible beneficial effects on the above three diseases at a certain dose.

CONCLUSIONS

Influencing gut barrier health may be a bridge for SCFAs (especially butyrate) to have positive effects on IBD, T1D, and NAFLD. It is expected that this article can provide new ideas for the subsequent research on the treatment of diseases by SCFAs and help SCFAs be better applied to precise and personalized treatment.

Intestinal Permeability Is a Mechanical Rheostat in the Pathogenesis of Liver Cirrhosis

Recent studies have suggested that an alteration in the gut microbiota and their products, particularly endotoxins derived from Gram-negative bacteria, may play a major role in the pathogenesis of liver diseases. Gut dysbiosis caused by a high-fat diet and alcohol consumption induces increased intestinal permeability, which means higher translocation of bacteria and their products and components, including endotoxins, the so-called "leaky gut". Clinical studies have found that plasma endotoxin levels are elevated in patients with chronic liver diseases, including alcoholic liver disease and nonalcoholic liver disease. A decrease in commensal nonpathogenic bacteria including Ruminococaceae and Lactobacillus and an overgrowth of pathogenic bacteria such as Bacteroidaceae and Enterobacteriaceae are observed in cirrhotic patients. The decreased diversity of the gut microbiota in cirrhotic patients before liver transplantation is also related to a higher incidence of post-transplant infections and cognitive impairment. The exposure to endotoxins activates macrophages via Toll-like receptor 4 (TLR4), leading to a greater production of proinflammatory cytokines and chemokines including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-8, which play key roles in the progression of liver diseases. TLR4 is a major receptor activated by the binding of endotoxins in macrophages, and its downstream signal induces proinflammatory cytokines. The expression of TLR4 is also observed in nonimmune cells in the liver, such as hepatic stellate cells, which play a crucial role in the progression of liver fibrosis that develops into hepatocarcinogenesis, suggesting the importance of the interaction between endotoxemia and TLR4 signaling as a target for preventing liver disease progression. In this review, we summarize the findings for the role of gut-derived endotoxemia underlying the progression of liver pathogenesis.

Serum Sphingosine-1-phosphate level and peritonitis in peritoneal dialysis patients

BACKGROUND

Given the important role of Sphingosine-1-phosphate (S1P) in maintaining the hemostasis in intestinal barrier function and regulation of inflammation and immune, we hypothesize that S1P might be a biomarker to predict peritonitis in peritoneal dialysis (PD) patients.

METHODS

In this case-control study, 78 stable, continuous ambulatory peritoneal dialysis patients were enrolled and followed for the episode of PD associated peritonitis. Patients were divided into two groups by whether or not they had peritonitis during follow-up: non-peritonitis (n = 65) and peritonitis (n = 13) group. S1P was analyzed by enzyme-linked immunosorbent assay. Logistic regression analysis was used to assess factors associated with peritonitis. The variables identified by univariable regression models (p < 0.1) were further selected into the multivariable logistic regression model to determine whether they could independently affect peritonitis.

RESULTS

Patients with peritonitis had a lower level of S1P than that of patients without peritonitis (1.3 ng/mL IQ 0.8, 3.6 ng/mL vs. 2.8 ng/mL IQ 1.5, 5.4 ng/mL, p = 0.018). The peritonitis group had lower serum albumin, lower blood leukocyte, lower hemoglobin and lower platelet count as compared to the non-peritonitis group. Logistic regression analysis showed that S1P (OR = 0.381, 95% CI = 0.171-0.848, p = 0.018), blood leukocyte count (OR = 0.438, 95% CI = 0.207-0.925, p = 0.030), and serum albumin (OR = 0.732, 95% CI = 0.556-0.962, p = 0.025) were independent factors associated with peritonitis in the present PD population.

CONCLUSION

Our study showed that S1P was an independent determinant of subsequent peritonitis in PD patients. S1P might serve as a biomarker to predict peritonitis in PD patients.

Phosphorylated‑myosin light chain mediates the destruction of small intestinal epithelial tight junctions in mice with acute liver failure

Tight junction dysregulation and epithelial damage contribute to intestinal barrier loss in patients with acute liver failure (ALF); however, the regulatory mechanisms of these processes remain poorly understood. The aim of the present study was to investigate the changes of intestinal tight junction and intestinal mucosa in mice with ALF and their mechanisms. In the present study, ALF was induced in mice through an intraperitoneal injection of D-galactosamine and lipopolysaccharide (D-GalN/LPS), and the morphological changes of the liver or small intestine were analyzed using hematoxylin and eosin staining, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The intestinal tissues and isolated serum were analyzed using western blotting, immunofluorescence staining and ELISA. D-GalN/LPS-induced mice exhibited signs of hepatocyte necrosis, alongside inflammatory cell infiltration into the liver tissue and partial microvilli detachment in the small intestinal mucosa. TEM demonstrated that the intestinal epithelial tight junctions were impaired, whereas SEM micrographs revealed the presence of abnormal microvilli in D-GalN/LPS-induced mice. In addition, the expression levels of phosphorylated (p)-myosin light chain (MLC), MLC kinase (MLCK) and Rho-associated kinase (ROCK) were significantly increased in the D-GalN/LPS-induced mice compared with those in the control mice, whereas the subsequent inhibition of MLCK or ROCK significantly reduced p-MLC expression levels. Conversely, the expression levels of occludin and zonula occludens-1 (ZO-1) were significantly decreased in the D-GalN/LPS-induced mice, and the inhibition of MLCK or ROCK significantly increased occludin and ZO-1 protein expression levels compared with those in the control group. Changes in the serum levels of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 were similar to the trend observed in p-MLC expression levels. In conclusion, the findings of the present study suggested that in a D-GalN/LPS-induced ALF model, TNF-α and IL-6 signaling may increase MLCK and ROCK expression levels, further mediate phosphorylation of MLC, which may result in tight junction dysregulation and intestinal barrier dysfunction.

Novel Insights Into Pathogenesis and Therapeutic Strategies of Hepatic Encephalopathy, From the Gut Microbiota Perspective

Since the 1950s, gradual changes in the gut microbiota of patients with hepatic encephalopathy have been observed. Previous research has indicated potential associations between the gut and brain, and the gut microbiota is becoming a hot topic in research on diseases of the nervous system. However, for the past few decades, studies of hepatic encephalopathy have been restricted to controlling the gut microbiota during macroscopic manipulation, such as probiotic intervention, while its clinical use remains controversial, and the cellular mechanisms underlying this condition are still poorly understood. This thesis seeks to comprehensively understand and explain the role of gut microbiota in hepatic encephalopathy as well as analyze the effects of intervention by regulating the gut microbiota. Evidence is presented that shows that dysbiosis of the gut microbiota is the primary pathological driver of hepatic encephalopathy and impacts pathologic progression via complex regulatory networks. As a result, suggestions were identified for future mechanistic research and improvements in therapeutic strategies for hepatic encephalopathy.

The effect of acute intragastric vs. intravenous alcohol administration on inflammation markers, blood lipids and gallbladder motility in healthy men

Ethanol intake increases plasma concentrations of triglycerides and chronic ethanol use impairs lipid metabolism and causes chronic inflammation. The gut plays an important role in metabolic handling of nutrients, including lipids, and a leaky gut associated with alcohol intake, allowing inflammatory signals to the portal vein, has been proposed to constitute a mechanism by which ethanol induces hepatic inflammation. We compared the effects of enteral and parenteral administration of ethanol on a range of circulating inflammation markers (including soluble CD163, a marker of liver macrophage activation), lipids, cholecystokinin (CCK) and fibroblast growth factor 19 (FGF19) as well as gallbladder volume. On two separate and randomized study days, we subjected healthy men (n = 12) to double-blinded intragastric ethanol infusion (IGEI) and isoethanolemic intravenous ethanol infusion (IVEI). Blood was sampled and ultrasonographic evaluation of gallbladder volume was performed at frequent intervals for 4 h after initiation of ethanol administration on both days. Little or no effects were observed on plasma levels of inflammation markers during IGEI and IVEI, respectively. Circulating levels of total, low-density lipoprotein and high-density lipoprotein cholesterol decreased after ethanol administration independently of the administration form. Triglyceride and very low-density lipoprotein (VLDL) cholesterol concentrations increased more after IGEI compared to IVEI. IVEI had no effect on plasma CCK and caused an increased gallbladder volume whereas IGEI elicited a CCK response (P < 0.0001) without affecting gallbladder volume. Circulating FGF19 concentrations decreased equally in response to both ethanol administration forms. In conclusion, by evaluating a range of circulating inflammation markers during IGEI and IVEI we were not able to detect signs of systemic low-grade inflammation originating from the presence of ethanol in the gut. IVEI increased gallbladder volume whereas IGEI increased plasma CCK (with neutral effect on gallbladder volume), increased plasma VLDL cholesterol and triglyceride concentrations; indicating that the enteral route of administration may influence ethanol's effects on lipid metabolism.

Pregnane X receptor activation by its natural ligand Ginkgolide-A improves tight junction proteins expression and attenuates bacterial translocation in cirrhosis

BACKGROUND AND AIMS

Pregnane X receptor (PXR) is a ligand-activated transcription factor and nuclear receptor expressed ubiquitously along gut-liver-axis. Inflammatory bowel disorders have been reported to implicate PXR in maintaining tight junction (TJ) integrity and countering inflammation. However, the hepatoprotective role of PXR activation in soothing bacterial translocation in liver cirrhosis has not been explored. Ginkgolide A (GA), a terpene trilactone from Ginkgo Biloba extract, is a natural ligand of rodent and human PXR. This study aims to investigate the effect of GA in activating PXR and improving associated tight junction integrity and reducing bacterial translocation in gut-liver axis of CCl₄ induced cirrhosis model.

METHODS

Swiss albino mice were administered with CCl₄ (0.5 ml/kg body weight, i.p) in corn oil for 12 weeks at an interval of two times a week. Following ascites induction, mice were randomized & administered 100 mg/kg body weight of GA through oral gavage for 2 weeks. At termination, blood, gut and liver tissues were collected for biochemical and molecular studies.

RESULTS

When compared to naïve mice, protein expression of hepatic and small intestinal PXR, CYP3A, ZO-1 and occludin were found to be significantly (p < 0.01) decreased in CCl₄ induced cirrhotic mice. Treatment with GA to cirrhotic mice significantly (p < 0.05) induced the expression of both hepatic and small intestinal PXR, CYP3A, ZO-1 and Occludin. Furthermore, increased (p < 0.01) hepatic and small intestinal NFκB was observed in CCl₄ induced cirrhotic mice that was significantly (p < 0.05) lowered following GA treatment. Over expression of TLR4/MyD88/NFκB axis and its downstream pro-inflammatory mediators TNF-α, IL6 and IFN-γ were observed in CCl₄ induced mice, and these indices were abrogated significantly after GA treatment. Furthermore, significantly increased plasma levels of bacterial translocation markers LBP and procalcitonin were found in CCl₄ mice, which were reduced significantly (p < 0.05 & p < 0.0001) after GA treatment.

CONCLUSION

In conclusion, our data supports the hypothesis that, GA treatment to CCl₄ induced cirrhotic mice, activated hepatic and small intestinal PXR and diminished inflammation, thereby improving tight junction integrity and attenuating bacterial translocation.

Gut Dysbiosis Associated With Hepatitis C Virus Infection

Background

Little is known about the effect of hepatitis C virus (HCV) infection on gut microbiota and the relationship between alteration of gut microbiota and chronic hepatitis C (CHC) progression. We performed a comparative study of gut microbiota composition between CHC patients and healthy individuals.

Methods

Fecal samples from 166 CHC patients were compared with those from 23 healthy individuals; the gut microbiota community was analyzed using 16S ribosomal RNA gene sequencing. CHC patients were diagnosed with persistently normal serum alanine aminotransferase without evidence of liver cirrhosis (LC) (PNALT, n = 18), chronic hepatitis (CH, n = 84), LC (n = 40), and hepatocellular carcinoma in LC (n = 24).

Results

Compared with healthy individuals, bacterial diversity was lower in persons with HCV infection, with a decrease in the order Clostridiales and an increase in Streptococcus and Lactobacillus. Microbiota dysbiosis already appeared in the PNALT stage with the transient increase in Bacteroides and Enterobacteriaceae. Predicted metagenomics of microbial communities showed an increase in the urease gene mainly encoded by viridans streptococci during CHC progression, consistent with a significantly higher fecal pH in CH and LC patients than in healthy individuals or those in the PNALT stage.

Conclusions

HCV infection is associated with gut dysbiosis, even in patients with mild liver disease. Additionally, overgrowth of viridans streptococci can account for hyperammonemia in CH and LC. Further studies would help to propose a novel treatment strategy because the gut microbiome can be therapeutically altered, potentially reducing the complications of chronic liver disease.

Role of endotoxemia in causing renal dysfunction in cirrhosis

Renal failure is a challenging problem in patients with cirrhosis since mortality increases with worsening renal function, hence the inclusion of serum creatinine in calculating the Model for End-Stage Liver Disease score for liver transplant evaluation. Among the various causes, infection is the leading etiology of mortality associated with cirrhosis. Bacterial infection frequently precipitates renal failure in patients with cirrhosis with the reported prevalence around 34%. Patients with cirrhosis are at increased risk of infections due to impaired immunity and increased gut permeability leading to bacterial translocation in the setting of portal hypertension. One of the most feared complications of severely decompensated liver and renal failure is hepatorenal syndrome, of which liver transplant may be the only available treatment. Furthermore, in those with spontaneous bacterial peritonitis and urinary tract infection, progressive renal failure occurs despite resolution of infection. Thus, the effects of endotoxemia on renal function in cirrhosis have become a major focus of research. The mechanisms of the damaging effects of endotoxin on renal function are complex but, in essence, involve dysregulated inflammation, circulatory dysfunction, poor clearance of endotoxin burden, as well as vasomotor nephropathy. In this article, we will review the mechanisms of endotoxemia-induced renal dysfunction in the setting of cirrhosis through the effects on renal blood flow, renal vascular endothelium, glomerular filtration rate, and tubular function.

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.

Sequential Changes in the Mesenteric Lymph Node Microbiome and Immune Response during Cirrhosis Induction in Rats

Cirrhosis severity in patients was previously shown to be associated with progressive changes in the fecal microbiome in a longitudinal setting. Recent evidence shows that bacterial translocation from the gut to the extraintestinal sites could play a major role in poor disease outcome and patient survival. However, the underlying mechanisms involving the microbiota in the disease progression are not well understood. Here, using an animal model of cirrhosis in a longitudinal and multibody sites setting, we showed the presence of a distinct composition of the microbiome in mesenteric lymph nodes, blood, and ascitic fluid compared to that in feces and ileocecal content, suggesting compartmentalization of the gut microbiome. We also demonstrate that microbiome changes in intestinal sites are associated with shifts in specific microbial groups in the mesenteric lymph nodes as well as an increase in systemic cytokine production, linking inflammation to decompensated cirrhosis in the gut-liver-immunity axis.

Whether the interaction between the gut microbiota and the immune response influences the evolution of cirrhosis is poorly understood. We aimed to investigate modifications of the microbiome and the immune response during the progression of cirrhosis. Rats were treated with carbon tetrachloride (CCl₄) to induce cirrhosis. We then assessed microbiome load and composition in stool, ileocecal contents (ICCs), mesenteric lymph nodes (MLNs), blood, and ascitic fluids (AFs) at 6, 8, and 10 weeks or ascites production and measured cytokine production in MLNs and blood. The microbiome of MLN, blood, and AF showed a distinct composition compared to that of stool and ICCs. Betaproteobacteria (Sutterella) were found associated with the appearance of a decompensated state of cirrhosis. Microbial load increased and showed a positive correlation with the relative abundance of pathobionts in the MLN of decompensated rats. Among several genera, Escherichia and “Candidatus Arthromitus” positively correlated with elevated levels of systemic proinflammatory cytokines. “Candidatus Arthromitus,” a segmented filamentous bacteria, was detected in ICC, MLN, and AF samples, suggesting a possible translocation from the gut to the AF through the lymphatic system, whereas Escherichia was detected in ICC, MLN, AF, and blood, suggesting a possible translocation from the gut to the AF through the bloodstream. In the present study, we demonstrate that microbiome changes in distinct intestinal sites are associated with microbial shifts in the MLNs as well as an increase in cytokine production, providing further evidence of the role the gut-liver-immunity axis plays in the progression of cirrhosis.

IMPORTANCE Cirrhosis severity in patients was previously shown to be associated with progressive changes in the fecal microbiome in a longitudinal setting. Recent evidence shows that bacterial translocation from the gut to the extraintestinal sites could play a major role in poor disease outcome and patient survival. However, the underlying mechanisms involving the microbiota in the disease progression are not well understood. Here, using an animal model of cirrhosis in a longitudinal and multibody sites setting, we showed the presence of a distinct composition of the microbiome in mesenteric lymph nodes, blood, and ascitic fluid compared to that in feces and ileocecal content, suggesting compartmentalization of the gut microbiome. We also demonstrate that microbiome changes in intestinal sites are associated with shifts in specific microbial groups in the mesenteric lymph nodes as well as an increase in systemic cytokine production, linking inflammation to decompensated cirrhosis in the gut-liver-immunity axis.

Noninvasive biomarkers of gut barrier function identify two subtypes of patients suffering from diarrhoea predominant-IBS: a case-control study

Background

Alterations of the small-intestinal permeability (s-IP) might play an essential role in both diarrhoea-predominant IBS (D-IBS) and celiac disease (CD) patients. Our aims were to analyse in D-IBS patients the symptom profile along with the levels of urinary sucrose (Su), lactulose (La), mannitol (Ma), and circulating biomarkers (zonulin, intestinal fatty acid binding protein - I-FABP, and diamine oxidase - DAO) of the gastrointestinal (GI) barrier function. The pro-inflammatory interleukins 6 and 8 (IL-6 and IL-8), the plasma values of lipopolysaccharide (LPS), and Toll-like receptor 4 (TLR-4) were also investigated. Besides, these biomarkers were compared with those in CD and healthy controls (HC). Finally, comparisons were performed between D-IBS patients with [D-IBS(+)] and without [D-IBS(−)] increased s-IP according to normal or altered La/Ma ratio.

Methods

The study included 39 D-IBS patients, 32 CD patients, and 20 HC. GI permeability was assayed by high-performance liquid chromatography determination in the urine of Su and La/Ma ratio. ELISA kits assayed circulating concentrations of zonulin, I-FABP, DAO, IL-6, IL-8, LPS, and TLR-4. The Mann–Whitney or the Kruskal–Wallis with Dunn’s post-test was used to assess differences among the groups.

Results

As for the La/Ma ratio, %Su, and I-FABP levels, D-IBS patients were significantly different from CD, but not HC. IL-6 levels were significantly higher in CD than HC, whereas IL-8 levels were significantly higher in both D-IBS and CD patients than HC. By opposite, LPS, and TLR-4 concentrations did not differ significantly among the groups. When D-IBS patients were categorised according to normal or altered s-IP, D-IBS(+) patients had %La, %Su, I-FABP, and DAO levels significantly higher than D-IBS(−) ones. The inflammatory parameters and markers of bacterial translocation (namely, IL-6 and LPS) were significantly higher in D-IBS(+) patients than D-IBS(−) ones.

Conclusions

The present study suggests that two distinct D-IBS subtypes could be identified. The investigation of possible s-IP alterations (i.e., considering the La/Ma ratio) might be useful to assess better and categorise this heterogeneous D-IBS population.

Trial registration

NCT01574209. Registered March 2012. First recruitment started in April 2012.

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.

Human fibroblast growth factor-21 serves as a predictor and prognostic factor in patients with hepatitis B cirrhosis combined with adrenal insufficiency

Hepatitis B cirrhosis is caused by liver cell necrosis, residual liver cell nodular regeneration, connective tissue hyperplasia and fiber formation, which frequently leads to adrenal insufficiency. Previous reports have demonstrated that human fibroblast growth factor (hFGF)-21 is a multifunctional protein that exhibits potential therapeutic value for metabolic diseases. The present study investigated the diagnostic value of hFGF-21 and analyzed the potential molecular mechanism in the progression of hepatitis B cirrhosis combined with adrenal insufficiency. Characteristics of cellular immunity and humoral immunity were analyzed in patients with hepatitis B cirrhosis combined with adrenal insufficiency (PhbA). Results demonstrated that expression levels of hFGF-21 were downregulated in plasma and liver cells isolated from clinical specimens. Plasma concentration levels of hFGF-21 were upregulated in prognostic PhbA. In vitro assays indicated that hFGF-21 treatment decreased the continuous deposition of extracellular matrix and reactive oxygen species in liver cells isolated from clinical specimens. Results also demonstrated that hFGF-21 treatment downregulated inflammatory cytokines. It was observed that hFGF-21 treatment downregulated nuclear factor (NF)-κB and Kruppel-like factor 6. Notably, transforming growth factor (TGF)-β, platelet-derived growth factor and epidermal growth factor levels were improved by hFGF-21 treatment. In conclusion, these results indicated that hFGF-21 inhibits inflammation by regulation of the NF-κB-mediated TGF-β signaling pathway, which may serve as a predictor and prognostic factor in PhbA.

Measurement of Microvascular Endothelial Barrier Dysfunction and Hyperpermeability In Vitro

Loss of microvascular endothelial barrier integrity leads to vascular hyperpermeability and vasogenic edema in a variety of disease processes including trauma, ischemia and sepsis. Understanding these principles gives valuable information on pathophysiology and therapeutic drug development. While animal models of traumatic and ischemic injuries are useful to understand vascular dysfunctions associated with such injuries, in vitro barrier integrity assays are reliable and helpful adjuncts to understand the cellular and molecular changes and signaling mechanisms that regulate barrier function. We describe here the endothelial monolayer permeability assay and transendothelial electrical resistance (TEER) measurement as in vitro methods to test changes in microvascular integrity and permeability. These in vitro assays are based on either the measurement of electrical resistance of the monolayer or the quantitative evaluation of fluorescently tagged molecules (e.g., FITC-dextran) that pass through the monolayer when there is damage or breakdown.

High-Altitude-Induced alterations in Gut-Immune Axis: A review

High-altitude sojourn above 8000 ft is increasing day by day either for pilgrimage, mountaineering, holidaying or for strategic reasons. In India, soldiers are deployed to these high mountains for their duty or pilgrims visit to the holy places, which are located at very high altitude. A large population also resides permanently in high altitude regions. Every year thousands of pilgrims visit Holy cave of Shri Amarnath ji, which is above 15 000 ft. The poor acclimatization to high altitude may cause alteration in immunity. The low oxygen partial pressure may cause alterations in gut microbiota, which may cause changes in gut immunity. Effect of high altitude on gut-associated mucosal system is new area of research. Many studies have been carried out to understand the physiology and immunology behind the high-altitude-induced gut problems. Few interventions have also been discovered to circumvent the problems caused due to high-altitude conditions. In this review, we have discussed the effects of high-altitude-induced changes in gut immunity particularly peyer's patches, NK cells and inflammatory cytokines, secretary immunoglobulins and gut microbiota. The published articles from PubMed and Google scholar from year 1975 to 2017 on high-altitude hypoxia and gut immunity are cited in this review.

Fecal microbiota transplantation prevents hepatic encephalopathy in rats with carbon tetrachloride-induced acute hepatic dysfunction

AIM

To investigate whether fecal microbiota transplantation (FMT) prevents hepatic encephalopathy (HE) in rats with carbon tetrachloride (CCl₄)-induced acute hepatic dysfunction.

METHODS

A rat model of HE was established with CCl₄. Rat behaviors and spatial learning capability were observed, and hepatic necrosis, intestinal mucosal barrier, serum ammonia levels and intestinal permeability were determined in HE rats receiving FMT treatment. Furthermore, the expression of tight junction proteins (Claudin-1, Claudin-6 and Occludin), Toll-like receptor (TLR) 4/TLR9, interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α was examined.

RESULTS

FMT improved rat behaviors, HE grade and spatial learning capability. Moreover, FMT prevented hepatic necrosis and intestinal mucosal barrier damage, leading to hepatic clearance of serum ammonia levels and reduced intestinal permeability. The expression of TLR4 and TLR9, two potent mediators of inflammatory response, was significantly downregulated in the liver of rats treated with FMT. Consistently, circulating pro-inflammatory factors such as interleukin (IL)-1β, IL-6 and tumor necrosis factor-α were remarkably decreased, indicating that FMT is able to limit systemic inflammation by decreasing the expression of TLR4 and TLR9. Importantly, HE-induced loss of tight junction proteins (Claudin-1, Claudin-6 and Occludin) was restored in intestinal tissues of rats receiving FMT treatment.

CONCLUSION

FMT enables protective effects in HE rats, and it improves the cognitive function and reduces the liver function indexes. FMT may cure HE by altering the intestinal permeability and improving the TLR response of the liver.

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

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

Novel treatment options for portal hypertension

Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications, such as variceal bleeding, ascites or hepatic encephalopathy. As such, clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis. At present, non-selective β-blockers, vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia. In contrast, safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue. In recent years, several preclinical and clinical trials have focused on this latter component and other therapeutic avenues. In this review, we highlight novel data in this context and address potentially interesting therapeutic options for the future.