The gut-brain axis (GBA) consists of bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive centers of the brain with peripheral intestinal functions. Recent advances in research have described the importance of gut microbiota in influencing these interactions. This interaction between microbiota and GBA appears to be bidirectional, namely through signaling from gut-microbiota to brain and from brain to gut-microbiota by means of neural, endocrine, immune, and humoral links. In this review we summarize the available evidence supporting the existence of these interactions, as well as the possible pathophysiological mechanisms involved. Most of the data have been acquired using technical strategies consisting in germ-free animal models, probiotics, antibiotics, and infection studies. In clinical practice, evidence of microbiota-GBA interactions comes from the association of dysbiosis with central nervous disorders (i.e. autism, anxiety-depressive behaviors) and functional gastrointestinal disorders. In particular, irritable bowel syndrome can be considered an example of the disruption of these complex relationships, and a better understanding of these alterations might provide new targeted therapies.

Accumulating evidence shows that oxidative stress plays an essential role in the pathogenesis and progression of many diseases. The imbalance between the production of reactive oxygen species (ROS) and the antioxidant systems has been extensively studied in pulmonary, neurodegenerative cardiovascular disorders; however, its contribution is still debated in gastrointestinal disorders. Evidence suggests that oxidative stress affects gastrointestinal motility in obesity, and post-infectious disorders by favoring the smooth muscle phenotypic switch toward a synthetic phenotype. The aim of this review is to gain insight into the role played by oxidative stress in gastrointestinal pathologies (GIT), and the involvement of ROS in the signaling underlying the muscular alterations of the gastrointestinal tract (GIT). In addition, potential therapeutic strategies based on the use of antioxidants for the treatment of inflammatory gastrointestinal diseases are reviewed and discussed. Although substantial progress has been made in identifying new techniques capable of assessing the presence of oxidative stress in humans, the biochemical-molecular mechanisms underlying GIT mucosal disorders are not yet well defined. Therefore, further studies are needed to clarify the mechanisms through which oxidative stress-related signaling can contribute to the alteration of the GIT mucosa in order to devise effective preventive and curative therapeutic strategies

Atrophic body gastritis (ABG) is an autoimmune condition eventually manifesting itself as pernicious anemia (PA). Parietal cell autoantibodies (PCAs) and intrinsic factor autoantibodies (IFAs) are considered characteristics of these conditions. Recent studies on IFA and PCA frequency with respect to cobalamin deficiency in biopsy-proven ABG patients are lacking. We addressed this issue using new enzyme-linked immunosorbent assay (ELISA)-based assays. Sera from 165 patients with histologically diagnosed ABG and 113 controls were tested for IFA and PCA using ELISA. A total of 81 ABG patients had cobalamin deficiency and macrocytic anemia (Group 1-PA), 36 had cobalamin deficiency without macrocytic anemia (Group 2), and 48 had normal cobalamin levels (Group 3). IFAs were detected in 44/165 ABG patients (27% sensitivity) and in 0/113 controls (100% specificity). PCAs were detected in 134 ABG patients (81% sensitivity) and in 11 controls (90% specificity). In Group 1, IFAs showed 37% sensitivity and 100% specificity, whereas PCAs showed 81% sensitivity and 90% specificity. Combining IFA and PCA testing increased the sensitivity to 61% in all ABG patients and to 73% in Group 1, while maintaining 100% specificity. IFAs are 100% specific for biopsy-proven ABG and occurred in 27% of patients. PCAs occurred in 81% of ABG patients and in 10% of controls. Combining IFA and PCA testing significantly increases their diagnostic performance for ABG and PA, yielding a 73% sensitivity for PA. The non-invasive combined PCA and IFA assessment may be useful in selecting patients at risk for autoimmune gastritis to be confi rmed by gastroscopic–histologic examination.

Probiotics are alive nonpathogenic microorganisms present in the gut microbiota that confer benefits to the host for his health. They act through molecular and cellular mechanisms that contrast pathogen bacteria adhesion, enhance innate immunity, decrease pathogen-induced inflammation, and promote intestinal epithelial cell survival, barrier function, and protective responses. Some of these beneficial effects result to be determined by secreted probiotic-derived factors that recently have been identified as "postbiotic" mediators. They have been reported for several probiotic strains but most available literature concerns Lactobacilli. In this review, we focus on the reported actions of several secretory products of different Lactobacillus species highlighting the available mechanistic data. The identification of soluble factors mediating the beneficial effects of probiotics may present an opportunity not only to understand their fine mechanisms of action, but also to develop effective pharmacological strategies that could integrate the action of treatments with live bacteria.

Autoimmune gastritis is often suspected for its hematologic findings, and rarely the diagnosis is made for the presence of gastrointestinal symptoms. Aims of this cross-sectional study were to assess in a large cohort of patients affected by autoimmune gastritis the occurrence and the pattern of gastrointestinal symptoms and to evaluate whether symptomatic patients are characterized by specific clinical features.Gastrointestinal symptoms of 379 consecutive autoimmune gastritis patients were systematically assessed and classified following Rome III Criteria. Association between symptoms and anemia pattern, positivity to gastric autoantibodies, Helicobacter pylori infection, and concomitant autoimmune disease were evaluated.In total, 70.2% of patients were female, median age 55 years (range 17-83). Pernicious anemia (53.6%), iron deficiency anemia (34.8%), gastric autoantibodies (68.8%), and autoimmune disorders (41.7%) were present. However, 56.7% of patients complained of gastrointestinal symptoms, 69.8% of them had exclusively upper symptoms, 15.8% only lower and 14.4% concomitant upper and lower symptoms. Dyspepsia, subtype postprandial distress syndrome was the most represented, being present in 60.2% of symptomatic patients. Univariate and multivariate analyses showed that age <55 years (OR 1.6 [CI:1-2.5]), absence of smoking habit (OR 2.2 [CI:1.2-4]), and absence of anemia (OR 3.1 [CI:1.5-6.4]) were independent factors associated to dyspepsia.Autoimmune gastritis is associated in almost 60% of cases with gastrointestinal symptoms, in particular dyspepsia. Dyspepsia is strictly related to younger age, no smoking, and absence of anemia.