Role of Microbiota-Derived Exosomes in Gut–Brain Communication for the Treatment of Brain Disorders

The human intestine hosts a plethora of bacterial species and other microbiota that can have significant implications on the homeostasis and diseased state of humans. The commensal and pathogenic bacteria both reside in the same environment of the intestinal epithelium, also called the gut-associated lymphoid tissues (GALT) of the host, which strike the balance to maintain the integrity of the intestinal barrier and immune function. On the contrary, there have been certain factors like diet, stress, age, inflammatory agents, etc. responsible for disrupting this balance and further causing the dysfunctioning of gut–brain communication. Recently, microbiota-derived exosomes have arisen as a promising alternative in the realms of gut–brain communication through interacting exosomal components with immune receptors. This chapter, in the beginning, discusses different types of bacterial exosomes, their biogenesis, and composition thereof. The role of gut microbiota in brain communication has been the focus of this chapter and is dealt with in detail along with the responsible mechanisms, which ultimately culminate in activating gut immune response by bacterial exosomes. This chapter also expounds on the role played by exosomes in neuropathogenesis and their implications in varied neurological disorders, including Alzheimer's disease, Parkinson's disease, etc.