SOTA: The Microbiota-Gut-Brain Axis: A Lens to Understanding Health, Disease, and Stress Across Species

Recent studies increasingly highlight the microbiome – the diverse collection of microbes living in and on us - as a key modulator of neurologic health and homeostatic maintenance. Crosstalk between the gut microbiome and the brain is mediated by nervous, humoral, metabolic, endocrine, and immune routes, resulting in bi-directional communication between microbiome and host. Advances in sequencing technologies have propelled microbiome research into a golden era, and increasingly reveal connections between neurodegenerative diseases, psychiatric disorders, and stress related behaviors in many different species. In human medicine, for example, the microbiota-gut-brain axis has been proposed as an novel intervention for treating not only neurodegenerative disorders like Parkinson’s, Alzheimer’s, and multiple sclerosis, but also mood disorders related to anxiety and depression. The gut brain axis may also be key in mitigating the effects of chronic stress. For example, the microbiome is both affected by chronic stress, as well as modulates how an individual responds to an environmental stressor. Unlike the host genome which remains fixed throughout life, the microbiome is potentially modifiable through diet, pre-, pro-, post-, and antibiotic use, and offers new targets for therapeutics. As clinicians, adoption of a holistic prospective which considers the combined potential of the host genome and microbiome, may lead to new strategies for health promotion and management of disease progression. Veterinarians have long observed the impact of the gut microbiome on neurologic health, and likely have already utilized the gut-brain axis to achieve a clinical outcome. A well-known example is hepatic encephalopathy, where modification the gut microbiota through antibiotic therapy and other medical management, can alleviate neurologic symptoms, sometimes to dramatic effect. The lens of microbiome science may yield new ways to address other conditions that may have a component of stress such as feline idiopathic cystitis, feline upper respiratory tract disease, inflammatory bowel disease, or inappropriate urination.  Perhaps the phrase attributed to Hippocrates “all diseases begin in the gut” is proving more insightful than we imagined.