Decoding the brain-body communication system

How the liver communicates with the brain in chronic disease

September 15, 2016

Body Talk 101

The body operates a sophisticated, multi-layered defense system designed to minimize damage from external forces and internal foes. Organs and other parts of the body are protected according to how vital their role is.

In particular, the body takes great lengths to protect the central nervous system (CNS), comprised of the brain and spinal cord. The command centre, located in the brain, processes, coordinates and influences all of the body's activities based on information gathered from the body by the CNS. 

The brain's role of central processing unit makes it highly valued and, as a result, its protection is the body's priority. The skull acts like a fortress, sheltering it from trauma and the spinal column acts as a shock absorber that reduces harmful jarring movements.

Other protective systems are on duty internally, such as the blood-brain barrier (BBB) which acts as a moat, effectively preventing the entry of dangerous cells and substances.

In addition to the BBB, the brain is equipped with its' own immune cells, known as microglia. Continually patrolling the brain, activated microglia are predominantly found at potential entry points, such as ventricles, guarding against infiltrators. Any rogue cells or pathogens (like bacteria or viruses) that manage to penetrate the BBB are met with robust resistance mounted by the ever-vigilant microglia cells.

They also perform quality control functions, pruning neurons, eliminating defective brain cells and defective or unused synapses. Communicating with neurons, microglia produce signals that stimulate and nourish the neuron's growth. 

Should damage occur in the brain either from trauma or an infection, the body dispatches its first responders, microglia, to the site to clear a path for healing by consuming dead microbes and neurons. 

But how do these brain immune cells receive and correctly process the flood of messages that are constantly emitted by the body's signaling system?

CIHR-funded researcher, Dr. Mark Gordon Swain, has built a multi-disciplinary team of experts who are decoding the complex brain-body communication system.  Based at the University of Calgary, they have uncovered a fundamental change in the way the brain functions when dealing with a chronic inflammatory disease. This important clue may be the key to better understanding the body's internal language. 

Dr. Swain's research has shown that chronic hepatitis-related inflammation in the liver does not remain localized to one region of the body. It is the same with other organs and conditions. Inflammatory bowel disease (ie. ulcerative colitis and Crohn's disease) and rheumatoid arthritis also commonly create dysfunction within the brain.

Working with animal models and through their clinical observations in people with chronic inflammatory diseases, Dr. Swain and his team have extensively documented the negative effects of chronic inflammation and how it causes disturbances in the brain.

Dr. Swain and Charlotte D'Mello in the lab.
Courtesy of Dr. Mark G. Swain, University of Calgary.

Associated with changes in the central nervous system, inflammation triggers behavioral changes like fatigue, lethargy, a general sense of malaise, and a loss of social interest. These symptoms are collectively termed as sickness behaviors that cause the body to pause and rest so that repair work can be undertaken in earnest.

However, in the setting of chronic disease these symptoms can become very problematic, making normal day-to-day living challenging.

Dr. Swain and his team are on the verge of finding the missing link that will pinpoint the changes that occur in the brain, that cause the fundamental neurological and psychological conditions commonly associated with chronic inflammatory diseases. 

It is hoped that their discoveries will lead to better targeted drug treatments and improved outcomes and quality of life for patients living with all types of diseases and chronic conditions.

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