Collateral Damage

Anti-cancer therapy and Autoimmune disease:  Part I

Collateral DamageBit of a detour in this post, as I’m going to be talking about Autoimmune diseases.  There is a cancer connection though, which is the current trials into the use of anti-cancer therapy to treat these Autoimmune conditions.  But, in order to explain how this works, I need to explain what Autoimmune diseases are.  So, that will be the subject of this post.  In the next one I’ll go on to discuss the current attempts to treat these diseases with chemotherapy and radiotherapy.

So.  Here we go.  Autoimmune disease 101:

Autoimmune diseases are caused by errors in the patient’s immune system.  Now, your immune system is there to do a very specific, very important job.  It’s there to protect you against infection.  The cells of your immune system circulate through your body, looking for anything that doesn’t belong.  If they find anything, they attack & destroy it.  This is how you fight off viruses, bacteria, fungal infections, etc.

So that’s what the immune system does.  It wanders about, looking for a fight.  But why doesn’t it start a fight with your own cells?  Well, as I described back in No Cure For Cancer…? every cell in your body has a protein on the outside called MHC, which acts like an “identity card” for the immune system.  So, normally, the immune system will ignore any cell which has the correct “identity card”, which is why it’s so hard to activate an immune response to cancer cells.

But, unfortunately, in some people this system breaks down.  Their immune systems stop recognising the “identity card” on some of their cells, which leads to them being incorrectly labelled as foreign invaders.  It’s a bit like the reports we’ve all heard from Iraq & Afghanistan, where innocent civilians are incorrectly identified as Enemy Combatants and blown to bits.  “Collateral Damage” is the oddly benign euphemism for this.  And the same thing happens in an Autoimmune disease.  So, the immune system goes on the offensive and starts to attack the supposed “foreign invaders”.

Different cell types come under attack in different Autoimmune diseases. In Rheumatoid Arthritis it is the joints. In Scleroderma it is the connective tissue that surrounds your blood vessels & major organs. And in MS it is a specialised cell type called oligodendrocytes.  I’m now going to describe the situation in MS, but similar events occur in Rheumatoid Arthritis, Scleroderma and other Autoimmine conditions.

So, in MS, the cells that comes under attack are the oligodendrocytes, which are part of your Central Nervous System (CNS).  The CNS is how information moves from your brain to your body and vice versa.  So, if you feel hot or cold, hurt yourself or feel hungry etc, then the information travels up the CNS to the brain.  If you decide to move your arms & legs, pick your nose or whatever, then your brain sends the appropriate signals to your body via the CNS.  Now, the signals work like electrical currents travelling through your nerves, in much the same way as the electricity running through the wires that power appliances like your TV, tablet, PC, etc.  In these appliances, the electrical wires  are covered in plastic insulation to prevent short circuits, which can damage the appliance, possibly irreparably.

And, in exactly the same way, your nerves are also covered in insulation to prevent “short circuits” in your CNS.  This biological insulator is called Myelin, and it is made by the oligodendrocytes.  So, in people with MS, the out-of-control immune response attacks & destroys the oligodendrocytes.  This means that their bodies can no longer make the insulating Myelin which protects the nerves in their CNS.  Therefore, their nerves become exposed, and this results in “short circuits” in their CNS.  And this is what causes the symptoms of MS.

In other Autoimmune conditions, the same thing happens.  In Rheumatoid arthritis, the painful swelling and deformation in the patients’ joints is caused by damage to the cartilage and bone.  In Scleroderma, damage to the connective tissue under the skin and around internal organs and blood vessels, leads to hard, painful swelling on the skin, circulatory problems and organ failure.  But in each case, like MS, the real issue in the aberrant, out-of-control immune response.

Right!  Now you have a (very!) brief description of Autoimmune diseases in general and MS in particular.  In the next post, I’ll go on to describe the potential of anti-cancer therapies for treating these conditions.

……………………………………..
Bell, E., & Bird, L. (2005). Autoimmunity Nature, 435 (7042), 583-583 DOI: 10.1038/435583a

ResearchBlogging.org

AG McCluskey (2016). Collateral Damage Zongo’s Cancer Diaries

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