Intestinal and Blood-Brain Barrier: Interface between Health and Diseases (pp. 277-297)
Authors: Aristo Vojdani and Joel Bautista
Abstract: The human body is an incredibly complex system, and since time immemorial man has struggled to work out what exactly his gut and his brain have to do with his health, and whether perhaps the two are connected somehow. We now know that the gut and the brain are both actually part of a marvelously intricate immune defense system, each doing its part to protect the body from sinister pathogenic invaders. Thus we have the intestinal barrier and the blood-brain barrier (BBB), two immune barrier systems that have the same purpose: to prevent invasion, infection and disease. This singularity of defensive purpose is reflected in the similarities between the gut and brain immune systems that extend to the actual structures, mechanisms and even biochemistries of the two systems. In fact, the two systems go beyond similarity, and actually communicate with and influence each other. Bidirectional signaling between the brain and gut has been confirmed by numerous studies. This communication between the gut and brain is ongoing from birth, and plays a significant role in shaping how the brain is wired. The gutís influence on the brain cannot be overestimated, so much so that it can be called a second brain. Studies have linked gastrointestinal diseases to autoimmune diseases and brain-linked disorders such as type 1 diabetes, depression, anxiety, multiple sclerosis and autism. There is an awareness now that neurodegenerative diseases may not exclusively have a neurological trigger. Uncontrolled chronic inflammation, disturbances in the gut microbiota and other gastrointestinal-related dysfunctions have been linked to neurodegenerative and autoimmune disorders and the failure first of intestinal and then blood-brain barrier function. This opens the possibility of prevention, amelioration and even reversal of autoimmune disorders through treatment modalities involving the repair of the intestinal barrier and the BBB, thus restoring the functionality of many organs.