Mental Disorders Linked to Crosstalk between The Gut Microbiome and The Brain

Food desert residence has limited impact on veteran fecal microbiome composition: a U.S. Veteran Microbiome Project study

IMPORTANCE

Social and economic inequities can have a profound impact on human health. The inequities could result in alterations to the gut microbiome, an important factor that may have profound abilities to alter health outcomes. Moreover, the strong correlations between social and economic inequities have been long understood. However, to date, limited research regarding the microbiome and mental health within the context of socioeconomic inequities exists. One particular inequity that may influence both mental health and the gut microbiome is living in a food desert. Persons living in food deserts may lack access to sufficient and/or nutritious food and often experience other inequities, such as increased exposure to air pollution and poor access to healthcare. Together, these factors may confer a unique risk for microbial perturbation. Indeed, external factors beyond a food desert might compound over time to have a lasting effect on an individual's gut microbiome. Therefore, adoption of a life-course approach is expected to increase the ecological validity of research related to social inequities, the gut microbiome, and physical and mental health.

Lactobacillus reuteri ATG-F4 Alleviates Chronic Stress-induced Anhedonia by Modulating the Prefrontal Serotonergic System

Mental health is influenced by the gut-brain axis; for example, gut dysbiosis has been observed in patients with major depressive disorder (MDD). Gut microbial changes by fecal microbiota transplantation or probiotics treatment reportedly modulates depressive symptoms. However, it remains unclear how gut dysbiosis contributes to mental dysfunction, and how correction of the gut microbiota alleviates neuropsychiatric disorders. Our previous study showed that chronic consumption of Lactobacillus reuteri ATG-F4 (F4) induced neurometabolic alterations in healthy mice. Here, we investigated whether F4 exerted therapeutic effects on depressive-like behavior by influencing the central nervous system. Using chronic unpredictable stress (CUS) to induce anhedonia, a key symptom of MDD, we found that chronic F4 consumption alleviated CUS-induced anhedonic behaviors, accompanied by biochemical changes in the gut, serum, and brain. Serum and brain metabolite concentrations involved in tryptophan metabolism were regulated by CUS and F4. F4 consumption reduced the elevated levels of serotonin (5-HT) in the brain observed in the CUS group. Additionally, the increased expression of Htr1a, a subtype of the 5-HT receptor, in the medial prefrontal cortex (mPFC) of stressed mice was restored to levels observed in stress-naïve mice following F4 supplementation. We further demonstrated the role of Htr1a using AAV-shRNA to downregulate Htr1a in the mPFC of CUS mice, effectively reversing CUS-induced anhedonic behavior. Together, our findings suggest F4 as a potential therapeutic approach for relieving some depressive symptoms and highlight the involvement of the tryptophan metabolism in mitigating CUS-induced depressive-like behaviors through the action of this bacterium.

Progress on traditional Chinese medicine in treatment of ischemic stroke via the gut-brain axis

Ischemic stroke is a common issue that severely affects the human health. Between the central nervous system and the enteric system, the " Gut-Brain " axis, the bidirectional connection involved in the neuro-immuno-endocrine network, is crucial for the occurrence and development of ischemic stroke. Ischemic stroke can lead to change in the gut microbiota and gastrointestinal hormones, which will then reversely affect the disease development. Traditional Chinese Medicine (TCM) has unique advantages with reference to the treatment for ischemic stroke. The latest research revealed that a significant portion of medicines and prescriptions of TCM exert their therapeutic effects by improving the gut microbiota and regulating the secretion of gastrointestinal hormones. The present review summarized the Chinese medicines that play a therapeutic role in cerebral ischemia through regulating the "Gut-Brain" axis and described the corresponding mechanisms. This study attempts to provide reference for clinical selection of Chinese medicines and helps better understand the relevant mechanisms of action.

Gut Barrier in Critical States of the Body

The intestinal barrier (IB) is a system of diffusion barriers separating the intestinal chyme and blood. The aim of the review is to identify the role of IB dysfunction in the formation of critical states of the body and to substantiate ways to prevent these states. Toxic substances produced by normal intestinal microflora are characterized. The involvement of endotoxin and ammonia in the pathogenesis of sepsis, acute circulatory disorders, secondary acute pulmonary lesions, and acute cerebral insufficiency is shown. Approaches to protect the IB in critical states of the body are proposed.

Secondary Dysfunction of the Intestinal Barrier in the Pathogenesis of Complications of Acute Poisoning

The last decade has been marked by an exponential increase in the number of publications on the physiological role of the normal human gut microbiota. The idea of a symbiotic relationship between the human organism and normal microbiota of its gastrointestinal tract has been firmly established as an integral part of the current biomedical paradigm. However, the type of this symbiosis varies from mutualism to parasitism and depends on the functional state of the host organism. Damage caused to the organism by external agents can lead to the emergence of conditionally pathogenic properties in the normal gut microbiota, mediated by humoral factors and affecting the outcome of exogenous exposure. Among the substances produced by symbiotic microbiota, there are an indefinite number of compounds with systemic toxicity. Some occur in the intestinal chyme in potentially lethal amounts in the case they enter the bloodstream quickly. The quick entry of potential toxicants is prevented by the intestinal barrier (IB), a set of structural elements separating the intestinal chyme from the blood. Hypothetically, severe damage to the IB caused by exogenous toxicants can trigger a leakage and subsequent systemic redistribution of toxic substances of bacterial origin. Until recently, the impact of such a redistribution on the outcome of acute exogenous poisoning remained outside the view of toxicology. The present review addresses causal relationships between the secondary dysfunction of the IB and complications of acute poisoning. We characterize acute systemic toxicity of such waste products of the normal gut microflora as ammonia and endotoxins, and demonstrate their involvement in the formation of such complications of acute poisoning as shock, sepsis, cerebral insufficiency and secondary lung injuries. The principles of assessing the functional state of the IB and the approaches to its protection in acute poisoning are briefly considered.

Insights in the Development and Uses of Alternatives to Antibiotic Growth Promoters in Poultry and Swine Production

The overuse and misuse of antibiotics has contributed to the rise and spread of multidrug-resistant bacteria. To address this global public health threat, many countries have restricted the use of antibiotics as growth promoters and promoted the development of alternatives to antibiotics in human and veterinary medicine and animal farming. In food-animal production, acidifiers, bacteriophages, enzymes, phytochemicals, probiotics, prebiotics, and antimicrobial peptides have shown hallmarks as alternatives to antibiotics. This review reports the current state of these alternatives as growth-promoting factors for poultry and swine production and describes their mode of action. Recent findings on their usefulness and the factors that presently hinder their broader use in animal food production are identified by SWOT (strength, weakness, opportunity, and threat) analysis. The potential for resistance development as well as co- and cross-resistance with currently used antibiotics is also discussed. Using predetermined keywords, we searched specialized databases including Scopus, Web of Science, and Google Scholar. Antibiotic resistance cannot be stopped, but its spreading can certainly be hindered or delayed with the development of more alternatives with innovative modes of action and a wise and careful use of antimicrobials in a One Health approach.