The Gut Microbial Bile Acid Modulation and Its Relevance to Digestive Health and Diseases

The human gut microbiome has been linked to numerous digestive disorders, but its metabolic products have been much less well characterized, in part due to the expense of untargeted metabolomics and lack of ability to process the data. In this review, we focused on the rapidly expanding information about the bile acid repertoire produced by the gut microbiome, including the impacts of bile acids on a wide range of host physiological processes and diseases, and discussed the role of short-chain fatty acids and other important gut microbiome-derived metabolites. Of particular note is the action of gut microbiome-derived metabolites throughout the body, which impact processes ranging from obesity to aging to disorders traditionally thought of as diseases of the nervous system, but that are now recognized as being strongly influenced by the gut microbiome and the metabolites it produces. We also highlighted the emerging role for modifying the gut microbiome to improve health or to treat disease, including the "engineered native bacteria'' approach that takes bacterial strains from a patient, modifies them to alter metabolism, and reintroduces them. Taken together, study of the metabolites derived from the gut microbiome provided insights into a wide range of physiological and pathophysiological processes, and has substantial potential for new approaches to diagnostics and therapeutics of disease of, or involving, the gastrointestinal tract.

The Role of Acupuncture on the Gut-Brain-Microbiota Axis in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a chronic dysfunction of the gastrointestinal tract, commonly characterized by abdominal pain or abdominal discomfort. These symptoms can substantially reduce the quality of life and work productivity of the patients. The exact pathogenesis of IBS remains unclear, as it has become apparent that multiple pathways are activated in the condition, including inflammation, immunology, neurology and psychology. Recent evidence has shown that symptoms in IBS are related to the dysfunction of the nervous system, particularly the viscerosomatic pathway, through immune-to-brain communication. The potential link between brain-gut relationships is gut microbiota. The management of IBS mostly focuses on symptomatically treating the patients. There are a wide range of standard treatments, including pharmacological to psychological interventions which are effective in some patients. Therefore, a combination of therapies including both standard and complimentary treatments, including Traditional Chinese Medicine (TCM) such as acupuncture, have been used in treating IBS patients. Several in vivo and clinical studies have demonstrated the efficacy of acupuncture in treating IBS. Increasing attention has been paid to research regarding the action mechanisms of acupuncture for IBS. This paper summarizes and discusses the possible mechanisms associated with acupuncture on the pathophysiology of IBS, including gastrointestinal (GI) motility, visceral hypersensitivity, the immune system, neurotransmitters, and the brain-gut axis. The results fromin vivo and clinical studies have been included. In addition, the effects of acupuncture on gut microbiota in IBS are included and any contradictory findings are deliberated.

Bi-directionality of Brain-Gut Interactions in Patients With Inflammatory Bowel Disease

BACKGROUND & AIMS

Inflammatory bowel diseases (IBD) are associated with mood disorders, such as anxiety or depression, but it is not clear whether one contributes to development of the other, or if the interaction is bi-directional (anxiety or depression contributes to the progression of IBD, and IBD affects psychological health). We performed a 2-year longitudinal prospective study of patients in secondary to care investigate the bi-directionality of IBD and mood disorders.

METHODS

We collected data from 405 adult patients with a diagnosis of Crohn's disease (CD) or ulcerative colitis (UC) from November 2012 through June 2017. Demographic features, subtypes of IBD, treatments, symptoms, somatization, and fecal level of calprotectin were recorded at baseline. IBD activity was determined at baseline and after the follow-up period (2 years or more) using the Harvey-Bradshaw Index for CD and the Simple Clinical Colitis Activity Index for UC (scores ≥5 used to define disease activity). Anxiety and depression data were collected using the Hospital Anxiety and Depression Scale (HADS), at baseline and after the follow-up period. Objective markers of disease activity, including glucocorticosteroid prescription or flare of disease activity, escalation of therapy, hospitalization secondary to IBD activity, and intestinal resection during follow-up were assessed via case note review. A brain-gut direction of disease activity was defined as development of new IBD activity in patients with quiescent IBD and abnormal HADS scores at baseline. A gut-brain direction of disease activity was defined by subsequent development of abnormal HADS scores in patients with active IBD and normal HADS scores at baseline. We performed multivariate Cox regression controlling for patient characteristics and follow-up duration.

RESULTS

Baseline CD or UC disease activity were associated with an almost 6-fold increase in risk for a later abnormal anxiety score (hazard ratio [HR], 5.77; 95% CI, 1.89-17.7). In patients with quiescent IBD at baseline, baseline abnormal anxiety scores were associated with later need for glucocorticosteroid prescription or flare of IBD activity (HR, 2.08; 95% CI, 1.31-3.30) and escalation of therapy (HR, 1.82; 95% CI, 1.19-2.80). These associations persisted when normal IBD activity index scores and fecal level of calprotectin <250 μg/g were used to define quiescent disease at baseline.

CONCLUSIONS

In a 2-year study of patients with CD or UC, we found evidence for bi-directional effects of IBD activity and psychological disorders. Patients with IBD should be monitored for psychological well-being.