Gut-brain-immune interactions: exploring probiotics as a drug delivery platform for neurological disease

The gut-brain-immune (GBI) axis, connecting gut microbes, neural tissue, and the cells of the immune system, plays a critical role in human health, particularly in relation to neurological diseases. Research in this field over the last few decades shows that disruptions in the microbiome have been linked to chronic inflammation, which may contribute to neurological conditions, including Parkinson's disease, Alzheimer's disease, and other mental health disorders. As we gain a greater understanding of the links between these systems, novel therapeutic strategies are being explored to treat disease by modulation of the GBI axis. One of the most promising approaches is the use of live biotherapeutics, such as engineered probiotics, as next-generation drug delivery systems. These live microorganisms can be designed to deliver specific therapeutic compounds to the gut and brain in order to modulate immune responses and reduce inflammation at the source. Probiotics and live biotherapeutics can offer a targeted approach to treating neurological diseases by influencing both the microbiome and immune system. In this review, we outline the research and mechanisms that have been implicated in GBI interactions and highlight the potential of these innovative therapies in treating neurological disorders, emphasizing their role in improving precision medicine through targeted, microbiome-based interventions.