Our body is not a sum of parts that operate independently of each other, but an integrated system that operates as one. The main controllers being the brain and the autonomic nervous systems.
In recent years, the topic of inflammation has become popular in science as more and more discoveries have pointed to increased cellular inflammation contributing to the pathogenesis and development of multiple chronic diseases such as cardiovascular disease, cancer, dementia, obesity and so forth.
The inflammatory status is controlled by the immune system. But as it turns out, the immune system is controlled by communication channels that occur via both branches of the autonomic nervous system.
A new study, published in Experimental Physiology, explores how the hypothalamus in the brain is also involved in immune system function and the inflammatory process.
What Causes Inflammation?
Inflammation in the body can be caused by multiple things – environmental, emotional, dietary. The inflammatory process in itself is a natural consequence of the body trying to constantly maintain a balance. Inflammation in cells provides signals to the brain that something isn’t right, and the brain communicates to the immune system to respond.
However, inflammatory molecules, known as cytokines don’t cross the blood brain barrier (BBB), so it’s remained a mystery as to how the brain manages to respond so quickly and efficiently to these responses.
The authors of this recent study suggest this super fast communication could occur via the circumventricular organs (CVOs), the vagal sensory system (VSS) and the spinal sensory system (SSS).
These are structures located near the brain ventricles and the authors propose that via a process of diffusion, molecules can cross the BBB and communicate with the brain.
The vagus nerve is the longest cranial nerve, which contains motor and sensory fibers that have been shown to communicate directly with the brain.
Evidence also suggests that the SSS can transmit immune information directly to the brain. The authors suggest that the SSS communicates via the liver portal system, which detects circulating inflammatory information and this helps inform the communication of the SSS with the brain.
The dance of information that is occurring at the organ, cell and tissue level informs the hypothalamus in the brain. The authors suggest that every point throughout the day, triggers, emotions, and feeding behavior activates an adjustment in the immune system to maintain balance.
Being that the brain is like the computer controller of the autonomous nervous system, the brain can initiate a fast and direct response.
The hypothalamus is also directly connected to hormonal release via endocrine organs such as the pituitary and adrenal glands. And hormones such as glucocorticoid aid the control of inflammatory molecules in the body.
What’s interesting about this study is the suggestion in the level of sensitivity of our immune function. For instance, even our emotional state can influence the inflammatory response. The authors state that “depression is known to be accompanied by antibody-mediated immune activation and depressed patients usually show increased levels of pro-inflammatory cytokines.”
While there is still much to be discovered, it is fascinating that the brain is so intricately connected to our immune system, keeping our body stable via activation of hormones and communication and activation of the autonomic nervous system.