The gut-brain axis in ischemic stroke: its relevance in pathology and as a therapeutic target

The gut contains the largest reservoir of microorganisms of the human body, termed as the gut microbiota which emerges as a key pathophysiological factor in health and disease. The gut microbiota has been demonstrated to influence various brain functions along the "gut-brain axis". Stroke leads to intestinal dysmotility and leakiness of the intestinal barrier which are associated with change of the gut microbiota composition and its interaction with the human host. Growing evidence over the past decade has demonstrated an important role of these post-stroke changes along the gut-brain axis to contribute to stroke pathology and be potentially druggable targets for future therapies. The impact of the gut microbiota on brain health and repair after stroke might be attributed to the diverse functions of gut bacteria in producing neuroactive compounds, modulating the host's metabolism and immune status. Therefore, a better understanding on the gut-brain axis after stroke and its integration in a broader concept of stroke pathology could open up new avenues for stroke therapy. Here, we discuss current concepts from preclinical models and human studies on the bi-directional communication along the microbiota-gut-brain axis in stroke.