Gut-liver axis and probiotics: Their role in non-alcoholic fatty liver disease

The incidence of obesity and its related conditions, including non-alcoholic fatty liver disease (NAFLD), has dramatically increased in all age groups worldwide. Given the health consequences of these conditions, and the subsequent economic burden on healthcare systems, their prevention and treatment have become major priorities. Because standard dietary and lifestyle changes and pathogenically-oriented therapies (e.g., antioxidants, oral hypoglycemic agents, and lipid-lowering agents) often fail due to poor compliance and/or lack of efficacy, novel approaches directed toward other pathomechanisms are needed. Here we present several lines of evidence indicating that, by increasing energy extraction in some dysbiosis conditions or small intestinal bacterial overgrowth, specific gut microbiota and/or a “low bacterial richness” may play a role in obesity, metabolic syndrome, and fatty liver. Under conditions involving a damaged intestinal barrier (“leaky gut”), the gut-liver axis may enhance the natural interactions between intestinal bacteria/bacterial products and hepatic receptors (e.g., toll-like receptors), thus promoting the following cascade of events: oxidative stress, insulin-resistance, hepatic inflammation, and fibrosis. We also discuss the possible modulation of gut microbiota by probiotics, as attempted in NAFLD animal model studies and in several pilot pediatric and adult human studies. Globally, this approach appears to be a promising and innovative add-on therapeutic tool for NAFLD in the context of multi-target therapy.

Pediatric non-alcoholic fatty liver disease: Recent solutions, unresolved issues, and future research directions

Non-alcoholic fatty liver disease(NAFLD) in children is becoming a major health concern. A "multiple-hit" pathogenetic model has been suggested to explain the progressive liver damage that occurs among children with NAFLD. In addition to the accumulation of fat in the liver, insulin resistance(IR) and oxidative stress due to genetic/epigenetic background, unfavorable lifestyles, gut microbiota and gut-liver axis dysfunction, and perturbations of trace element homeostasis have been shown to be critical for disease progression and the development of more severe inflammatory and fibrotic stages [non-alcoholic steatohepatitis(NASH)]. Simple clinical and laboratory parameters, such as age, history, anthropometrical data(BMI and waist circumference percentiles), blood pressure, surrogate clinical markers of IR(acanthosis nigricans), abdominal ultrasounds, and serum transaminases, lipids and glucose/insulin profiles, allow a clinician to identify children with obesity and obesity-related conditions, including NAFLD and cardiovascular and metabolic risks. A liver biopsy(the "imperfect" gold standard) is required for a definitive NAFLD/NASH diagnosis, particularly to exclude other treatable conditions or when advanced liver disease is expected on clinical and laboratory grounds and preferably prior to any controlled trial of pharmacological/surgical treatments. However, a biopsy clearly cannot represent a screening procedure. Advancements in diagnostic serum and imaging tools, especially for the non-invasive differentiation between NAFLD and NASH, have shown promising results, e.g., magnetic resonance elastography. Weight loss and physical activity should be the first option of intervention.Effective pharmacological treatments are still under development; however, drugs targeting IR, oxidative stress, proinflammatory pathways, dyslipidemia, gut microbiota and gut liver axis dysfunction are an option for patients who are unable to comply with the recommended lifestyle changes. When morbid obesity prevails, bariatric surgery should be considered.

Management of cholelithiasis in Italian children:A national multicenter study

AIM:To evaluate the management of Italian children with cholelithiasis observed at Pediatric and Surgical Departments linked to Italian Society of Pediatric Gastroenterology Hepatology and Nutrition. METHODS: One-hundred-eighty children (90 males, median age at diagnosis 7.3 years; range, 0-18 years) with echographic evidence of cholelithiasis were enrolled in the study; the data were collected by an anonymous questionnaire sent to participating centers. RESULTS: One hundred seventeen patients were treated with ursodeoxycholic acid; in 8 children dissolution of gallstones was observed, but the cholelithiasis recurred in 3 of them. Sixty-five percent of symptomatic children treated became asymptomatic. Sixty-four patients were treated with cholecystectomy and in only 2 cases a postoperative complication was reported. Thirty- four children received no treatment and were followed with clinical and echographic controls; in no case thedevelopment of complications was reported. CONCLUSION: The therapeutic strategies were extremely heterogeneous. Ursodeoxycholic acid was ineffective in dissolution of gallstones but it had a positive effect on the symptoms. Laparoscopic cholecystectomy was confirmed to be an efficacy and safe treatment for pediatric gallstones.

Persistent hypertransaminasemia in asymptomatic children: A stepwise approach

We aimed to examine the major causes of isolated chronic hypertransaminasemia in asymptomatic children and develop a comprehensive diagnostic flow diagram. A MEDLINE search inclusive of publications throughout August 2012 was performed. We found only a small number of publications that had comprehensively investigated this topic. Consequently, it was difficult to construct a diagnostic flowchart similar to those already available for adults. In children, a "retesting panel" prescription, including gamma-glutamyl transpeptidase and creatine kinase in addition to aminotransferases, is considered a reasonable approach for proficiently confirming the persistence of the abnormality, ruling out cholestatic hepatopathies and myopathies, and guiding the subsequent diagnostic steps. If re-evaluation of physical and historical findings suggests specific etiologies, then these should be evaluated in the initial enzyme retesting panel. A simple multistep diagnostic algorithm incorporating a large number of possible pediatric scenarios, in addition to the few common to adults, is available. Accurately classifying a child with asymptomatic persistent hypertransaminas-emia may be a difficult task, but the results are critical for preventing the progression of an underlying, possibly occult, condition later in childhood or during transition. Given the high benefit/cost ratio of preventing hepatic deterioration, no effort should be spared in diagnosing and properly treating each case of persistent hypertransaminasemia in pediatric patients.

The gut-liver axis as a target of liver disease management

The interplay between the gut and liver,the so called“gut-liver axis”(GLA),plays a significant role in health and disease.As shown in Figure 1,the GLA is regulated by a number of equally relevant interacting factors including gut microbiota,integrity and function of the intestinal wall,antigen trafficking,mucosal innate immune response,and oxidative stress(1,2).In addition to undigested or unabsorbed food and microorganisms,the gut lumen contains also their fermentation/metabolic products,bile,mucus,and epithelial cells spontaneously exfoliated from the gastrointestinal mucosa.The latter is composed of various cell types counting immune cells,goblet cells,and enterocytes strongly connected by tight junctions and covered with a mucus layer that acts as a dynamic barrier.Recent elucidation of a gut-vascular barrier(GVB)has revealed this structure to intervene to control gut bacteria and antigen translocation from the gut into the blood stream(3).Interestingly,diseases that are characterized or aggravated by impairment of the barrier function(so-called“leaky gut”)and/or particular patterns of the microbiome(e.g.,a lack of balance between Bacteroides and Firmicutes)are not restricted to the intestinal tract and liver.Some relevant examples are represented by diabetes type 1,familial Mediterranean fever,obesity,cardiovascular disease,decreased bone-mass density,autism,dysregulation of immune response and systemic allergic diseases(1).