Immune System Involvement

How does the IMMUNE system affect my pain and what can I do about it?

Prepared by Coralie Wales and reviewed by Dr John Quintner and the Chronic Pain Switzerland National Advisory Panel

The immune system works to protect you. It is amazing! It consists of tiny cells which have the ability to chatter with each other and with the cells of the nervous system all the time, just so they can be super aware of everything that is happening in your internal AND external environment, all the time. They can respond to anything that is a potential threat, thereby keeping you safe and ensuring your survival. At the same time, they can just chatter about anything ("How's the weather over there in the foot? ..." "Not bad, our temperature is a bit up this morning, pressure is pretty normal though"...)

To understand how this happens, lets go back to basics.

When you are in pain, there may be a part of that experience of pain that is due to inflammation. Firstly, lets look at what this word means. It comes from the Latin "inflammare" which means "to inflame". The important part of that word is "flame" as in fire. People experiencing inflammation often describe it as hot and burning. Inflammation is a "localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful, especially as a reaction to injury or infection", according to the New Oxford Dictionary of English.

Inflammation is caused by chemicals released by the immune system in response to foreign substances (like if you scratch yourself and some dirt or sand gets into the skin) or if you are exposed to bacteria, viruses or cancers. The immune system releases chemicals which attack "invaders", and there are other immune system chemicals that make the area quite sensitive so that you avoid using it.

The chemicals responsible for inflammation make the surrounding body tissues much more sensitive (this process is called peripheral sensitization). This is why when you fall over and hurt your foot and it becomes inflamed you find that the whole foot is sore, not just the part that you hurt originally. This short-term inflammation is great because you then protect your foot while it heals.

Inflammation can be short-term, like when you bump your knee on the coffee table, but there are some conditions, like osteo-arthritis which can involve long term wear of the joints, and this can then become long-term inflammation. There are also some conditions that can involve long-term inflammation because of over-activity of the immune system. This is called "auto-immunity" where the immune system becomes really sensitive to lots of things and can make people quite sick. Conditions that can involve auto-immunity include rheumatoid arthritis, multiple sclerosis, ulcerative colitis, asthma, Hashimoto's thyroiditis and many others.

Researchers have also found that there is a genetic component in some autoimmune conditions such as rheumatoid arthritis.

By the way, any condition or disease that ends with "-itis" means that inflammation is involved. For example, sinusitis is inflammation in the sinuses. "Arthritis" is inflammation of the joints ("Arth" indicates joints, from the Greek "arthron" meaning joint).

Apart from inflammation there is another way the immune system protects you. When it has attacked an invader it has the ability to remember the invader, so that the next time it comes across it, it is able to more efficiently mount an attack on it. This is the principle behind immunisation such as when we have a tetanus shot or get our children immunised against chickenpox. The immune system can grow immunity against the foreign substance in the body.

The immune system watches over your health, and it can do this both close up but also from a distance. For example, researchers have now shown that when you hurt your finger, apart from your finger becoming inflamed, chemicals become active in your spine too.

These chemicals released in your spine, just like the inflammatory chemicals we just described, can make the nearby tissues in the spinal cord much more sensitive, and your pain can spread and worsen.

What can happen once these spinal cord immune cells become active?

  1. This process seems to contribute to a phenomenon that scientists call "central nervous system sensitisation". Everything becomes more sensitive. This sensitivity makes pain worse - it is like opening the gate for more pain to be experienced.
  2. The release of these chemicals can also cause fever, malaise, fatigue, sleepiness, loss of appetite, loss of libido (sex drive), social withdrawal, irritability and heightened sensitivity to everyday activities causing increased pain (hyperalgesia). This group of symptoms is known as the stress or sickness response.

 

Once these immune cells of the brain and spinal cord become active many of the clinical features of the puzzling pain condition known as fibromyalgia syndrome can be explained. In fibromyalgia increased pain sensitivity is a prominent feature. There appears to be many possible triggers for this condition, which may be an example of an extended stress of sickness response.

What triggers these spinal cord immune cells to become activated?

We all know what psychological stress is because we experience it from time to time in our daily lives when we are under pressure. There are also other kinds of stress that can trigger our bodies to react and protect itself, these are called "stressors" and can include:

  1. Nervous system infections and injury
  2. Prolonged use of codeine or high dose morphine (the development of opioid tolerance and opioid induced hypersensitivity can be at least in part explained this way)
  3. Physical stress or when we push our body too hard by overdoing exercise or doing too many activities in one day.
  4. Chronic stress, like being enmeshed in a disputed workers compensation situation or caring for a chronically ill family member, can trigger this immune response

What can I do about it?

Does any of the above sound familiar to you? Are you trapped in a chronically stressful situation? It is possible that your immune system is turned on continuously in an attempt to rectify the situation and protect you.

This is the most important part. One of the first things you can do if you think you are experiencing this process is to look at how you can better manage the stress or stressors in your life. Lifestyle issue such as diet and sleep may also need attention. High doses of marine lipids (such as omega 3 fish oil) have been found useful to combat inflammatory processes in joints and are worthy of consideration by those who prefer not to take non-steroidal anti-inflammatory drugs. Please see the pages on "pacing", "exercising with pain" and "relaxation techniques" to find out more about what you can do.