Season 3, Episode 4: I Dream of Genomes

The San Francisco outbreak somehow has spread to Boston and NorBAC follows to track down the cause. Bob discovers the deaths aren’t due to the virus itself but to patients’ overactive immune responses to the virus. Meanwhile, David finally meets Angelica Starov, the researcher who wants to use gene therapy to tackle Owen’s addictive tendencies.

Image provided courtesy of Shaftesbury Films.

NorBAC scientist Bob Melnikov.

IS IT POSSIBLE FOR THE IMMUNE SYSTEM TO KILL THE PERSON IT IS SUPPOSED TO PROTECT?

How does the immune system become overactive?

Image provided courtesy of AXS Studio Inc and Shaftesbury Films.

The “Sinatra” virus, lurking in the bloodstream.

When the immune system fights infectious agents, cells close to the site of infection release cytokines – proteins that immune system cells hone in on. The cytokines activate these cells which, in turn, causes the cells to release more cytokines to amplify the signal.

Normally, the body is able to keep the amplification just right, so not too many cytokines are released and not too many immune system cells are activated. Sometimes, however, the body’s ability to regulate cytokine release breaks down and gives rise to what’s called a cytokine storm. Cytokine storms can hyper-activate the immune system and lead to dangerous levels of inflammation which, if left unchecked, can be life threatening.

How is inflammation life-threatening?

Usually, inflammation is localized to a site of injury or infection. Blood vessels in the area dilate to allow more disease-fighting immune cells to come to the site, which causes redness, swelling and heat. The swelling pinches nearby nerves, which can cause pain. When localized, inflammation lasts just long enough for immune system cells to fight off bacteria in the area.

Occasionally, inflammation can become systemic, meaning the characteristic swelling, heat, and pain can affect the whole body. Systemic inflammation that arises from infection is also called sepsis. Sepsis can occur after surgery, from severe trauma, burns, or cytokine storms. In septic patients, systemic blood vessel dilation severely reduces blood pressure, slows blood flow, and reduces the amount of oxygen delivered to cells and tissues to dangerously low levels. This can sometimes cause organ failure and death.

So…

Yes, it is possible to die from an immune response like sepsis. The only way to completely stop systemic inflammation is to eliminate the infection.

IS IT PROBABLE THAT BLOCKING THE DOPAMINE PATHWAY IN THE BRAIN CAN STOP ADDICTION?

Image provided courtesy of Shaftesbury Films.

David chats with scientist Angelica Starov about her research, which uses gene therapy to treat addictive behaviour.

What is the dopamine pathway?

Dopamine is a natural chemical made by the nervous system that can act on some nerve cells in the brain. The dopamine pathway is sometimes referred to as the dopamine reward system or the brain’s pleasure system.

Certain chemicals and behaviours—drugs, alcohol or sex, for example— may bring the user or doer a sense of pleasure. These same chemicals or behaviours also have been shown to cause an increase in the amount of dopamine in certain parts of the brain. It is thought that increased dopamine strengthens communication circuits between nerve cells. And stronger circuits are hallmarks of learning.

So, it’s thought that dopamine plays a role in the brain “learning” what triggers pleasure and in driving a person to seek more of that pleasure.

Can the dopamine pathway be blocked?

Yes. Some mood stabilizing drugs, so-called “neuroleptics,” block dopamine receptors—dopamine-binding brain proteins—preventing them from activating nerve cells, and blocking communication between cells. Interestingly, cocaine also blocks the dopamine pathway, but in a way that actually increases the reward system—not a good way to “cure” addiction. Cocaine blocks the proteins that remove dopamine from between nerve cells, which prolongs the “reward” signals in the brain.

So…

It is possible to use drugs or chemicals to interfere with the dopamine pathway and the brain’s reward system, which may then interfere with addictive behaviours. However, as the cocaine example shows, blocking the dopamine pathway might not always have the desired effect.

- by Audrey M. Huang, Ph.D.

Want to read and learn more?

To learn more about inflammation, visit:
http://en.wikipedia.org/wiki/Inflammation

For more information about addiction, go to:
http://www.nida.nih.gov/

To read about dopamine, visit:
http://en.wikipedia.org/wiki/Dopamine
http://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_que/i_03_m_que.html