Antibiotics are usually prescribed to cure infections but they also have significant modulatory effects on the gut microbiota. Several alterations of the intestinal bacterial community have been reported during antibiotic treatment, including the reduction of beneficial bacteria as well as of microbial alpha-diversity. Although after the discontinuation of antibiotic therapies it has been observed a trend towards the restoration of the original condition, the new steady state is different from the previous one, as if antibiotics induced some kind of irreversible perturbation of the gut microbial community. The poorly absorbed antibiotic rifaximin seem to be different from the other antibiotics, because it exerts non-traditional effects additional to the bactericidal/bacteriostatic activity on the gut microbiota. Rifaximin is able to reduce bacterial virulence and translocation, has anti-inflammatory properties and has been demonstrated to positively modulate the gut microbial composition. Animal models, culture studies and metagenomic analyses have demonstrated an increase in Bifidobacterium, Faecalibacterium prausnitzii and Lactobacillus abundance after rifaximin treatment, probably consequent to the induction of bacterial resistance, with no major change in the overall gut microbiota composition. Antibiotics are therefore modulators of the symbiotic relationship between the host and the gut microbiota. Specific antibiotics, such as rifaximin, can also induce eubiotic changes in the intestinal ecosystem; this additional property may represent a therapeutic advantage in specific clinical settings.
Portal vein thrombosis (PVT) is one of the most common complications occurring during the natural course of liver cirrhosis. Even though PVT is often asymptomatic, the worsening of liver function, an unexpected episode of gastrointestinal bleeding or ascitic decompensation may be landmarks of PVT development. Beyond these clinical manifestations, it is debated whether PVT really has an impact on liver cirrhosis natural history or rather represents only one of its consequences. Probably PVT development should not only be considered as a matter of impaired blood flow or pro-coagulation tendency. On one hand, PVT seems a consequence of the worsening in portal vein outflow due to the increased hepatic resistance in cirrhotic livers. On the other hand, vascular microthrombosis secondary to necroinflammation may cause liver ischemia and infarction, with loss of hepatic tissue (parenchymal extinction) which is replaced by fibrotic tissue. Therefore, PVT might also be considered as the overt manifestation of the liver fibrosing process evolution and anticoagulant therapy may thus have microscopic indirect effects also on the progression of liver disease. At present, a connection between PVT development and the progression of liver fibrosis/cirrhosis has not yet been demonstrated. Nevertheless, it is not clear if PVT development may worsen cirrhotic patients' outcome by itself. Some authors tried to assess liver transplant benefit in PVT cirrhotic patients but data are contrasting. In this review, we will try to answer these questions, providing a critical analysis of data reported in literature.
Liver cirrhosis is a paradigm of intestinal dysbiosis. The qualitative and quantitative derangement of intestinal microbial community reported in cirrhotic patients seems to be strictly related with the impairment of liver function. A kind of gut microbial "fingerprint", characterized by the reduced ratio of "good" to "potentially pathogenic" bacteria has recently been outlined, and is associated with the increase in Model for End-Stage Liver Disease and Child Pugh scores. Moreover, in patients presenting with cirrhosis complications such as spontaneous bacterial peritonitis (SBP), hepatic encephalopathy (HE), and, portal hypertension intestinal microbiota modifications or the isolation of bacteria deriving from the gut are commonly reported. Rifaximin is a non-absorbable antibiotic used in the management of several gastrointestinal diseases. Beyond bactericidal/bacteriostatic, immune-modulating and anti-inflammatory activity, a little is known about its interaction with gut microbial environment. Rifaximin has been demonstrated to exert beneficial effects on cognitive function in patients with HE, and also to prevent the development of SBP, to reduce endotoxemia and to improve hemodynamics in cirrhotics. These results are linked to a shift in gut microbes functionality, triggering the production of favorable metabolites. The low incidence of drug-related adverse events due to the small amount of circulating drug makes rifaximin a relatively safe antibiotic for the modulation of gut microbiota in advanced liver disease.
Anti-tumor necrosis factor (TNF)-α agents represent an effective treatment for chronic inflammatory diseases. However, some concerns about their potentially undesirable effects on liver function have been reported. On the other hand, evidence of their therapeutic effects on certain liver diseases is accumulating. Many data showed the safety of anti-TNF-α in patients with chronic hepatitis B and C and in liver transplanted patients even if a strict follow-up and prophylaxis are recommended in well-defined subgroups. On the other side, anti-TNF-α-induced liver injury is not a rare event. However, it is often reversible after anti-TNF-α withdrawal. Anti-TNF-α agents have been tested in advanced stages of severe alcoholic hepatitis and non-alcoholic fatty liver disease. Limited data on the efficacy of anti-TNF-α in patients with autoimmune hepatitis and primary biliary cholangitis are also available. In this review, we explored the hepatic safety concerns in patients receiving anti-TNF-α agents with and without pre-existent hepatic diseases. In addition, the available evidence on their potential benefits in the treatment of specific hepatic diseases is discussed.
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