Microbiota represents the entire microbial community present in the gut host. It serves several functions establishing a mutualistic relation with the host. Latest years have seen a burst in the number of studies focusing on this topic, in particular on intestinal diseases. In this scenario, Proteobacteria are one of the most abundant phyla, comprising several known human pathogens. This review highlights the latest findings on the role of Proteobacteria not only in intestinal but also in extraintestinal diseases. Indeed, an increasing amount of data identifies Proteobacteria as a possible microbial signature of disease. Several studies demonstrate an increased abundance of members belonging to this phylum in such conditions. Major evidences currently involve metabolic disorders and inflammatory bowel disease. However, more recent studies suggest a role also in lung diseases, such as asthma and chronic obstructive pulmonary disease, but evidences are still scant. Notably, all these conditions are sustained by various degree of inflammation, which thus represents a core aspect of Proteobacteria-related diseases.

Gutmicrobiotahas gainedincreasinginterestin the pathogenesisofimmune-related diseases. We reviewedtherole ofgutmicrobiotain the normaldevelopmentof immune systemand its involvementin graft-versus-hostdisease, focusingon dataavailableon humans.Gutmicrobiotahas gainedincreasinginterestin the pathogenesisofimmune-related diseases. We reviewedtherole ofgutmicrobiotain the normaldevelopmentof immune systemand its involvementin graft-versus-hostdisease, focusingon dataavailableon humans.

Acute diarrhea is a burdensome disease with potentially harmful consequences, especially in childhood. Despite its large use in clinical practice, the efficacy of the probiotic Bacillus clausii in treating acute childhood diarrhea remains unclear. Our objective was to systematically review the efficacy of Bacillus clausii in the treatment of acute childhood diarrhea. The following electronic databases were systematically searched up to October 2017: MEDLINE (via PubMed/OVID), EMBASE (via OVID), Cochrane Central Database of Controlled Trials (via CENTRAL), Google Scholar, and ClinicalTrials.gov. Only randomized controlled trials were included. The overall effect for the meta-analysis was derived by using a random effects model. Six randomized controlled trials (1298 patients) met the eligibility criteria. Data arising from pooled analysis showed that Bacillus clausii significantly reduced the duration of diarrhea (mean difference = −9.12 h; 95% confidence interval [CI]: −16.49 to −1.75, p = 0.015), and the duration of hospitalization (mean difference = −0.85 days; 95% CI: −1.56 to −0.15, p = 0.017), compared with control. There was a trend of decreasing stool frequency after Bacillus clausii administration compared with the control group (mean difference = −0.19 diarrheal motions; 95% CI: −0.43 to −0.06, p = 0.14). Bacillus clausii may represent an effective therapeutic option in acute childhood diarrhea, with a good safety profile.

In recent years, there has been an increasing interest on muscle wasting, considering the reduction of quality of life and the increase of morbidity and mortality associated. Sarcopenia and cachexia represent two conditions of reduction of muscle mass, sharing several elements involved in their pathogenesis, such as systemic inflammation, impaired muscle protein synthesis, increased muscle apoptosis, mitochondrial dysfunction in skeletal muscle tissue and insulin resistance. These features often characterize cancer, inactivity or denervation, but also inflammatory diseases, such as chronic obstructive pulmonary disease, renal failure, cardiac failure, rheumatoid arthritis, inflammatory bowel disease and aging in general. The gastrointestinal tract and gut microbiota are thought to be deeply associated with muscle function and metabolism, although the exact mechanisms that link gut with skeletal muscle are still not well known. This review summarized the potential pathways linking gut with muscle, in particular in conditions as sarcopenia and cachexia. The main emerging pathways implicated in the skeletal muscle-gut axis are: the myostatin/activin signaling pathway, the IGF1/PI3K/AKT/mTOR signaling pathway, which results suppressed, the NF-kB signaling pathway and the FOXO signaling pathway. Further researches in this field are necessary to better explain the linkage between gut microbiota and muscle wasting and the possible emerging therapies associated.