Gut microbiota and liver disease

Hepatic circadian clock oscillators and nuclear receptors integrate microbiome-derived signals

The liver is a key organ of metabolic homeostasis with functions that oscillate in response to food intake. Although liver and gut microbiome crosstalk has been reported, microbiome-mediated effects on peripheral circadian clocks and their output genes are less well known. Here, we report that germ-free (GF) mice display altered daily oscillation of clock gene expression with a concomitant change in the expression of clock output regulators. Mice exposed to microbes typically exhibit characterized activities of nuclear receptors, some of which (PPARα, LXRβ) regulate specific liver gene expression networks, but these activities are profoundly changed in GF mice. These alterations in microbiome-sensitive gene expression patterns are associated with daily alterations in lipid, glucose, and xenobiotic metabolism, protein turnover, and redox balance, as revealed by hepatic metabolome analyses. Moreover, at the systemic level, daily changes in the abundance of biomarkers such as HDL cholesterol, free fatty acids, FGF21, bilirubin, and lactate depend on the microbiome. Altogether, our results indicate that the microbiome is required for integration of liver clock oscillations that tune output activators and their effectors, thereby regulating metabolic gene expression for optimal liver function.

Breathomics--exhaled volatile organic compound analysis to detect hepatic encephalopathy: a pilot study

The current diagnostic challenge with diagnosing hepatic encephalopathy (HE) is identifying those with minimal HE as opposed to the more clinically apparent covert/overt HE. Rifaximin, is an effective therapy but earlier identification and treatment of HE could prevent liver disease progression and hospitalization. Our pilot study aimed to analyse breath samples of patients with different HE grades, and controls, using a portable electronic (e) nose. 42 patients were enrolled; 22 with HE and 20 controls. Bedside breath samples were captured and analysed using an uvFAIMS machine (portable e-nose). West Haven criteria applied and MELD scores calculated. We classify HE patients from controls with a sensitivity and specificity of 0.88 (0.73-0.95) and 0.68 (0.51-0.81) respectively, AUROC 0.84 (0.75-0.93). Minimal HE was distinguishable from covert/overt HE with sensitivity of 0.79 and specificity of 0.5, AUROC 0.71 (0.57-0.84). This pilot study has highlighted the potential of breathomics to identify VOCs signatures in HE patients for diagnostic purposes. Importantly this was performed utilizing a non-invasive, portable bedside device and holds potential for future early HE diagnosis.

Impact of dietary fat on the development of non-alcoholic fatty liver disease in Ldlr-/- mice

The prevalence of non-alcoholic fatty liver disease (NAFLD) has increased in parallel with central obesity and is now the most common chronic liver disease in developed countries. NAFLD is defined as excessive accumulation of lipid in the liver, i.e. hepatosteatosis. The severity of NAFLD ranges from simple fatty liver (steatosis) to non-alcoholic steatohepatitis (NASH). Simple steatosis is relatively benign until it progresses to NASH, which is characterised by hepatic injury, inflammation, oxidative stress and fibrosis. Hepatic fibrosis is a risk factor for cirrhosis and primary hepatocellular carcinoma. Our studies have focused on the impact of diet on the onset and progression of NASH. We developed a mouse model of NASH by feeding Ldlr-/- mice a western diet (WD), a diet moderately high in saturated and trans-fat, sucrose and cholesterol. The WD induced a NASH phenotype in Ldlr-/- mice that recapitulates many of the clinical features of human NASH. We also assessed the capacity of the dietary n-3 PUFA, i.e. EPA (20 : 5,n-3) and DHA (22 : 6,n-3), to prevent WD-induced NASH in Ldlr-/- mice. Histologic, transcriptomic, lipidomic and metabolomic analyses established that DHA was equal or superior to EPA at attenuating WD-induced dyslipidemia and hepatic injury, inflammation, oxidative stress and fibrosis. Dietary n-3 PUFA, however, had no significant effect on WD-induced changes in body weight, body fat or blood glucose. These studies provide a molecular and metabolic basis for understanding the strengths and weaknesses of using dietary n-3 PUFA to prevent NASH in human subjects.

Correlation between small intestinal bacterial overgrowth and dendritic cell phenotype and function in cirrhotic patients with hepatitis B

AIM: To investigate the relationship between dendritic cells (DCs) and small intestinal bacterial overgrowth (SIBO) in cirrhotic patients with hepatitis B.

METHODS: Flow cytometry was used to analyze the counts of peripheral blood DCs in 47 cirrhotic patients with HBV infection and 15 healthy volunteers. SIBO was determined by lactulose hydrogen breath test (LHBT).

RESULTS: Of the 47 cirrhotic patients, 22 (46.8%) had SIBO, which was significantly higher than that in healthy controls (6.7%, P = 0.005). The prevalence of SIBO increased with the Child-Pugh classification of cirrhosis (A: 18.2%, B: 43.8% and C: 65%). The prevalence of SIBO in patients with decompensated cirrhosis was significantly higher than that in patients with compensated cirrhosis (55.6% vs 18.2%, P = 0.030). The expression of CD80, CD83, and CD1a on the surface of DCs in cirrhotic patients was significantly lower than that in healthy controls (P < 0.05). The expression rates of CD80, CD83, CD1a and HLA-DR on the surface of DCs in SIBO positive cirrhotic patients were lower than those in SIBO negative cirrhotic patients (17.22% ± 2.08% vs 22.13% ± 2.34%, 24.65% ± 1.47% vs 34.52% ± 2.84%, 14.05% ± 1.33% vs 17.40% ± 3.22%, 81.47% ± 7.56% vs 70.15% ± 6.32%, P < 0.05).

CONCLUSION: The functional abnormality of DCs in cirrhotic patients with hepatitis B is associated with the presence of SIBO.

Microbiome and bacterial translocation in cirrhosis

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

Gut microbiota and non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common disorder with poorly understood pathogenesis. Beyond environmental and genetic factors, cumulative data support the causative role of gut microbiota in disease development and progression.

DATA SOURCE

We performed a PubMed literature search with the following key words: "non-alcoholic fatty liver disease", "non-alcoholic steatohepatitis", "fatty liver", "gut microbiota" and "microbiome", to review the data implicating gut microbiota in NAFLD development and progression.

RESULTS

Recent metagenomic studies revealed differences in the phylum and genus levels between patients with fatty liver and healthy controls. While bacteroidetes and firmicutes remain the dominant phyla among NAFLD patients, their proportional abundance and genera detection vary among different studies. New techniques indicate a correlation between the methanogenic archaeon (methanobrevibacter smithii) and obesity, while the bacterium akkermanshia municiphila protects against metabolic syndrome. Among NAFLD patients, small intestinal bacterial overgrowth detected by breath tests might induce gut microbiota and host interactions, facilitating disease development.

CONCLUSIONS

There is evidence that gut microbiota participates in NAFLD development through, among others, obesity induction, endogenous ethanol production, inflammatory response triggering and alterations in choline metabolism. Further studies with emerging techniques are needed to further elucidate the microbiome and host crosstalk in NAFLD pathogenesis.

Caring for children with NAFLD and navigating their care into adulthood

NAFLD is the most common chronic liver disease in children and adults, with its prevalence closely associated with obesity and other features of the metabolic syndrome. As young adults with NAFLD transition from the paediatric care environment to adult services, establishing a coordinated model of transition to ensure ongoing and appropriate care is critical. Enabling a smooth transfer begins with an understanding of the key differences between paediatric and adult NAFLD as well as the psychosocial factors that affect older adolescents. This Review summarizes the literature on paediatric NAFLD from the past two decades with a focus on the differences in epidemiology, pathology, pathophysiology and treatment that are relevant to clinicians who transition paediatric patients to adult care. An integrated model, which employs a team of adult and paediatric providers who can address the psychosocial, cognitive and logistical challenges of transition, provides the best opportunity for a seamless and coordinated transfer to adult care.

Potential for dietary ω-3 fatty acids to prevent nonalcoholic fatty liver disease and reduce the risk of primary liver cancer

Nonalcoholic fatty liver disease (NAFLD) has increased in parallel with central obesity, and its prevalence is anticipated to increase as the obesity epidemic remains unabated. NAFLD is now the most common cause of chronic liver disease in developed countries and is defined as excessive lipid accumulation in the liver, that is, hepatosteatosis. NAFLD ranges in severity from benign fatty liver to nonalcoholic steatohepatitis (NASH), and NASH is characterized by hepatic injury, inflammation, oxidative stress, and fibrosis. NASH can progress to cirrhosis, and cirrhosis is a risk factor for primary hepatocellular carcinoma (HCC). The prevention of NASH will lower the risk of cirrhosis and NASH-associated HCC. Our studies have focused on NASH prevention. We developed a model of NASH by using mice with the LDL cholesterol receptor gene ablated fed the Western diet (WD). The WD induces a NASH phenotype in these mice that is similar to that seen in humans and includes robust induction of hepatic steatosis, inflammation, oxidative stress, and fibrosis. With the use of transcriptomic, lipidomic, and metabolomic approaches, we examined the capacity of 2 dietary ω-3 (n-3) polyunsaturated fatty acids, eicosapentaenoic acid (20:5ω-3; EPA) and docosahexaenoic acid (22:6ω-3; DHA), to prevent WD-induced NASH. Dietary DHA was superior to EPA at attenuating WD-induced changes in plasma lipids and hepatic injury and at reversing WD effects on hepatic metabolism, oxidative stress, and fibrosis. The outcome of these studies suggests that DHA may be useful in preventing NASH and reducing the risk of HCC.

Bifidobacterium pseudocatenulatum CECT 7765 Reduces Obesity-Associated Inflammation by Restoring the Lymphocyte-Macrophage Balance and Gut Microbiota Structure in High-Fat Diet-Fed Mice

BACKGROUND/OBJECTIVES

The role of intestinal dysbiosis in obesity-associated systemic inflammation via the cross-talk with peripheral tissues is under debate. Our objective was to decipher the mechanisms by which intervention in the gut ecosystem with a specific Bifidobacterium strain reduces systemic inflammation and improves metabolic dysfunction in obese high-fat diet (HFD) fed mice.

METHODS

Adult male wild-type C57BL-6 mice were fed either a standard or HFD, supplemented with placebo or Bifidobacterium pseudocatenulatum CECT 7765, for 14 weeks. Lymphocytes, macrophages and cytokine/chemokine concentrations were quantified in blood, gut, liver and adipose tissue using bead-based multiplex assays. Biochemical parameters in serum were determined by ELISA and enzymatic assays. Histology was assessed by hematoxylin-eosin staining. Microbiota was analyzed by 16S rRNA gene pyrosequencing and quantitative PCR.

RESULTS

B. pseudocatenulatum CECT 7765 reduced obesity-associated systemic inflammation by restoring the balance between regulatory T cells (Tregs) and B lymphocytes and reducing pro-inflammatory cytokines of adaptive (IL-17A) and innate (TNF-α) immunity and endotoxemia. In the gut, the bifidobacterial administration partially restored the HFD-induced alterations in microbiota, reducing abundances of Firmicutes and of LPS-producing Proteobacteria, paralleled to reductions in B cells, macrophages, and cytokines (IL-6, MCP-1, TNF-α, IL-17A), which could contribute to systemic effects. In adipose tissue, bifidobacterial administration reduced B cells whereas in liver the treatment increased Tregs and shifted different cytokines (MCP-1 plus ILP-10 in adipose tissue and INF-γ plus IL-1β in liver). In both tissues, the bifidobacteria reduced pro-inflammatory macrophages and, TNF-α and IL-17A concentrations. These effects were accompanied by reductions in body weight gain and in serum cholesterol, triglyceride, glucose and insulin levels and improved oral glucose tolerance and insulin sensitivity in obese mice.

CONCLUSIONS

Here, we provide evidence of the immune cellular mechanisms by which the inflammatory cascade associated with diet-induced obesity is attenuated by the administration of a specific Bifidobacterium strain and that these effects are associated with modulation of gut microbiota structure.

Gut microbiota disturbance and non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), also called fatty liver, is the most common chronic liver disease. Although the prevalence of NAFLD is increasing, the mechanisms underlying its pathogenesis are incompletely understood. So far, there has been no effective approach for its prevention and treatment. With the development of next generation sequencing technology, recent studies have shown that gut microbiota alterations including changes in the composition of gut flora, bacterial translocation and small intestinal bacterial overgrowth, play roles in the development of NAFLD. Besides destruction of the intestinal barrier, the most important pathogenic mechanism of gut microbiota distrubance is the facilitation of bacteria and their toxic products to reach the liver through the gut liver-axis. The hepatic immune system is activated through pattern recognition receptors, such as Toll-like and NOD-like receptor signaling pathways. The release of pro-inflammatory cytokines including tumor necrosis factor and interleukins results in liver injury, which progresses to NAFLD. Application of probiotics, antibiotics and fecal microbiota transplantation has shown efficiency, which provides new targets for the prevention and treatment of NAFLD.

Review article: Alcohol and gut microbiota - the possible role of gut microbiota modulation in the treatment of alcoholic liver disease

BACKGROUND

Alcohol abuse represents the most common cause of liver disease in the Western countries. Pre-clinical and clinical studies showed that alcohol consumption affects amount and composition of gut microbiota. Moreover, gut flora plays an important role in the pathogenesis of alcoholic liver injury.

AIM

To review the relationship between alcohol administration and changes on gut microbiota, its involvement in the pathogenesis of alcoholic liver disease, and how gut microbiota modulation could be a target for the treatment of alcoholic liver disease.

METHODS

Articles were identified using the PubMed database with the search terms 'Alcohol', 'Gut Microbiota', 'Alcoholic liver disease', 'Probiotic', 'Prebiotic', 'Symbiotic' and 'Antibiotic'. English-language articles were screened for relevance. Full review of publications for the relevant studies was conducted, including additional publications that were identified from individual article reference lists.

RESULTS

Alcohol abuse induces changes in the composition of gut microbiota, although the exact mechanism for this alteration is not well known. The translocation of bacterial products into the portal blood appears to play a key role in alcohol-induced liver damage. Several studies show that the modulation of gut microbiota seem to be a promising strategy to reduce alcohol-induced liver injury.

CONCLUSIONS

Further studies are needed to better understand the relationship between alcohol administration and changes in gut microbiota, and its involvement in alcoholic liver disease. Moreover larger studies are needed to confirm the preliminary results on the therapeutic effects of gut microbiota modulation.

Gut microbiota: its role in hepatic encephalopathy

Ammonia, a key factor in the pathogenesis of hepatic encephalopathy (HE), is predominantly derived from urea breakdown by urease producing large intestinal bacteria and from small intestine and kidneys, where the enzyme glutaminases releases ammonia from circulating glutamine. Non-culture techniques like pyrosequencing of bacterial 16S ribosomal ribonucleic acid are used to characterize fecal microbiota. Fecal microbiota in patients with cirrhosis have been shown to alter with increasing Child-Turcotte-Pugh (CTP) and Model for End stage Liver Disease (MELD) scores, and with development of covert or overt HE. Cirrhosis dysbiosis ratio (CDR), the ratio of autochthonous/good bacteria (e.g. Lachnospiraceae, Ruminococcaceae and Clostridiales) to non-autochthonous/pathogenic bacteria (e.g. Enterobacteriaceae and Streptococcaceae), is significantly higher in controls and patients with compensated cirrhosis than patients with decompensated cirrhosis. Although their stool microbiota do not differ, sigmoid colonic mucosal microbiota in liver cirrhosis patients with and without HE, are different. Linkage of pathogenic colonic mucosal bacteria with poor cognition and inflammation suggests that important processes at the mucosal interface, such as bacterial translocation and immune dysfunction, are involved in the pathogenesis of HE. Fecal microbiome composition does not change significantly when HE is treated with lactulose or when HE recurs after lactulose withdrawal. Despite improving cognition and endotoxemia as well as shifting positive correlation of pathogenic bacteria with metabolites, linked to ammonia, aromatic amino acids and oxidative stress, to a negative correlation, rifaximin changes gut microbiome composition only modestly. These observations suggest that the beneficial effects of lactulose and rifaximin could be associated with a change in microbial metabolic function as well as an improvement in dysbiosis.

Gut microbiota and liver diseases

Several studies revealed that gut microbiota are associated with various human diseases, e.g., metabolic diseases, allergies, gastroenterological diseases, and liver diseases. The liver can be greatly affected by changes in gut microbiota due to the entry of gut bacteria or their metabolites into the liver through the portal vein, and the liver-gut axis is important to understand the pathophysiology of several liver diseases, especially non-alcoholic fatty liver disease and hepatic encephalopathy. Moreover, gut microbiota play a significant role in the development of alcoholic liver disease and hepatocarcinogenesis. Based on these previous findings, trials using probiotics have been performed for the prevention or treatment of liver diseases. In this review, we summarize the current understanding of the changes in gut microbiota associated with various liver diseases, and we describe the therapeutic trials of probiotics for those diseases.

Novel insights into the mechanisms whereby isoflavones protect against fatty liver disease

Fatty liver disease (FLD) is a growing public health problem worldwide. There is an urgent requirement for alternative and natural medicine to treat this disease. As phytochemicals, isoflavones have attracted considerable attention for the prevention of FLD. Numerous studies have revealed that isoflavones protect against FLD through various pathways which modulate fatty acid β-oxidation, lipid synthesis, and oxidative stress. Recently, the aldose reductase (AR)/polyol pathway has been reported to be involved in the development of FLD by modulating hepatic fructose production, peroxisome proliferator-activated receptor (PPAR)α activity, cytochrome P450 (CYP)2E1 expression, and gut bacterial endotoxin-induced cytokine release. It has been reported that some isoflavones are potent AR inhibitors. Here, we review the anti-FLD actions of isoflavones and the proposed mechanism whereby isoflavones protect against FLD, with regard to the AR/polyol pathway. We propose that isoflavones block the AR/polyol pathway and in turn reduce fructose production and subsequent fat accumulation in the liver in diabetic or high-glucose-diet mice. In addition, in rodents with alcoholic liver disease or nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, inhibition of AR by isoflavones may improve PPARα-mediated fatty acid oxidation, reduce hepatic steatosis, and attenuate CYP2E1-mediated oxidative stress or AR/gut bacterial endotoxin-mediated cytokine overproduction, to alleviate progression of FLD.

Gut-liver axis in alcoholic liver disease

Alcoholic liver disease (ALD) has been among the leading causes of cirrhosis and liver-related death worldwide for decades. Early discoveries in alcoholic liver disease identified increased levels of bacterial endotoxin in the portal circulation, suggesting a role for gut-derived toxins in ALD. Indeed, alcohol consumption can disrupt the intestinal epithelial barrier and result in increased gut permeability that increasingly is recognized as a major factor in ALD. Bacterial endotoxin, lipopolysaccharide, is a prototypic microbe-derived inflammatory signal that contributes to inflammation in ALD through activation of the Toll-like receptor 4. Recent studies also have shown that alcohol consumption is associated with alterations in the gut microbiome, and the dysbalance of pathogenic and commensal organisms in the intestinal microbiome may contribute to the abnormal gut-liver axis in ALD. Indeed, bacterial decontamination improves ALD both in human and animal models. This short review summarizes recent findings and highlights emerging trends in the gut-liver axis relevant to ALD.

Lean-non-alcoholic fatty liver disease increases risk for metabolic disorders in a normal weight Chinese population

AIM: To study the prevalence and clinical biochemical, blood cell and metabolic features of lean-non-alcoholic fatty liver disease (lean-NAFLD) and its association with other diseases.

METHODS: Demographic, biochemical and blood examinations were conducted in all the subjects in this study. We classified the subjects into four groups according to their weight and NAFLD status: lean-control, lean-NAFLD [body mass index (BMI) < 24 kg/m²], overweight-obese control and overweight-obese NAFLD. One-way analysis of variance (ANOVA) was used to compare the means of continuous variables (age, BMI, blood pressure, glucose, lipid, insulin, liver enzymes and blood cell counts) and the χ² test was used to compare the differences in frequency of categorical variables (sex, education, physical activity, smoking, alcohol consumption and prevalence of hypertension, hyperlipidemia, diabetes, metabolic syndrome central obesity and obesity). Both univariate and multivariate logistic regression models were adopted to calculate odds ratios (ORs) and predict hyperlipidemia, hypertension, diabetes and metabolic syndrome when we respectively set all controls, lean-control and overweight-obese-control as references. In multivariate logistic regression models, we adjusted potential confounding factors, including age, sex, smoking, alcohol consumption and physical activity.

RESULTS: The prevalence of NAFLD was very high in China. NAFLD patients were older, had a higher BMI, waist circumference, blood pressure, fasting blood glucose, insulin, blood lipid, liver enzymes and uric acid than the controls. Although lean-NAFLD patients had lower BMI and waist circumstance, they had significantly higher visceral adiposity index than overweight-obese controls. Lean-NAFLD patients had comparable triglyceride, cholesterin and low-density lipoprotein cholesterin to overweight-obese NAFLD patients. In blood cell examination, both lean and overweight-obese NAFLD was companied by higher white blood cell count, red blood cell count, hemoglobin and hematocrit value. All NAFLD patients were at risk of hyperlipidemia, hypertension, diabetes and metabolic syndrome (MetS). Lean-NAFLD was more strongly associated with diabetes (OR = 2.47, 95%CI: 1.14-5.35), hypertension (OR = 1.72, 95%CI: 1.00-2.96) and MetS (OR = 3.19, 95%CI: 1.17-4.05) than overweight-obese-NAFLD (only OR for MetS was meaningful: OR = 1.89, 95%CI: 1.29-2.77). NAFLD patients were more likely to have central obesity (OR = 1.97, 95%CI: 1.38-2.80), especially in lean groups (OR = 2.17, 95%CI: 1.17-4.05).

CONCLUSION: Lean-NAFLD has unique results in demographic, biochemical and blood examinations, and adds significant risk for diabetes, hypertension and MetS in lean individuals.

Microbiota and the gut-liver axis: Bacterial translocation, inflammation and infection in cirrhosis

Liver disease is associated with qualitative and quantitative changes in the intestinal microbiota. In cirrhotic patients the alteration in gut microbiota is characterized by an overgrowth of potentially pathogenic bacteria (i.e., gram negative species) and a decrease in autochthonous familiae. Here we summarize the available literature on the risk of gut dysbiosis in liver cirrhosis and its clinical consequences. We therefore described the features of the complex interaction between gut microbiota and cirrhotic host, the so called “gut-liver axis”, with a particular attention to the acquired risk of bacterial translocation, systemic inflammation and the relationship with systemic infections in the cirrhotic patient. Such knowledge might help to develop novel and innovative strategies for the prevention and therapy of gut dysbiosis and its complication in liver cirrhosis.

The microbiome in early life: self-completion and microbiota protection as health priorities

This minireview considers the benefits of refocusing attention away from treating the patient as a mammalian human to managing the complete patient: a majority microbial superorganism. Under the "completed self" model for formation of the human-microbial superorganism, the single, most pivotal sign in distinguishing a life course of health versus that filled with disease is self-completion (i.e., seeding of the minority mammalian human by the majority microbial portion of the symbiont). From a disease prevention perspective, microbial seeding at birth and subsequent nurturing of the microbiota are significant steps to reduce the risk of both noncommunicable diseases (e.g., type 1 diabetes) and certain infectious diseases. Management of the microbiome during pregnancy, birth, and shortly thereafter appears to be the most significant critical window for healthy superorganism formation. However, the bolus for microbiota seeding at birth and the nurturing process are subject to environmental influences and disruption, such as exposure to toxic chemicals and drugs, infections, and other physical and psychological stressors. Additionally, childhood and adult corrective measures, such as fecal transplantation and administration of prebiotics and probiotics, while potentially useful, may have limitations that are yet to be fully defined. This minireview considers (1) basic features of management of the microbiome to facilitate self-completion, (2) protection of the microbiota from environmental hazards, and (3) the benefits of using a superorganism focus for health management beginning with pregnancy and extending throughout childhood and adult life.

Low Levels of 25-Hydroxy Vitamin D are Independently Associated with the Risk of Bacterial Infection in Cirrhotic Patients

OBJECTIVES:

Low levels of vitamin D are associated with a higher mortality in cirrhotic patients, but the role of this deficiency is still unknown. The purpose of this study was to assess the levels of vitamin D in cirrhotic patients with and without bacterial infection.

METHODS:

25-hydroxy (25-OH) vitamin D was assessed by immunoassay in 88 patients hospitalized in our hepatology unit.

RESULTS:

The causes of cirrhosis were mainly alcohol (70%), hepatitis C (10%), or both (9%). Infections (n=38) mainly included bacteriemia (21%), urinary tract infections (24%), and spontaneous bacterial peritonitis (29%). A severe deficiency in vitamin D (<10 ng/ml) was observed in 56.8% of patients. Infections were more frequent in patients with a severe deficiency compared with the others (54 vs. 29%, P=0.02). A severe deficiency in vitamin D was a predictive factor of infection (odds ratio=5.44 (1.35–21.97), P=0.017) independently of the Child–Pugh score (odds ratio=2.09 (1.47–2.97) P=0.00004) and the C-reactive protein level (odds ratio=1.03 (1.002–1.052), P=0.03) in a logistic regression also including the alanine amino transferase (not significant). By a Cox regression analysis, only the presence of an infection was significantly associated with mortality (relative risk=3.24 (1.20–8.76), P=0.02) in a model also associating the Child–Pugh score (not significant) and the presence of a severe deficiency in vitamin D (not significant).

CONCLUSIONS:

Low levels of 25-OH vitamin D were independently associated with bacterial infections in cirrhotic patients. The impact of 25-OH vitamin D supplementation on the infection rate and death of cirrhotic patients should be assessed in randomized trials.