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Immune cells

WHAT IS AUTOIMMUNITY?

A LOSS OF IMMUNE TOLERANCE

An Autoimmune Disease occurs when your immune system produces autoantibodies against self-antigens and starts to attack your own body tissue(s) causing inflammation, symptoms and damage.  What are autoantibodies and self-antigens?  An autoantibody is an antibody (a type of protein) produced by the immune system, that is directed against one or more of the individual's own body proteins (self antigens).  For example, in Multiple Sclerosis, auto-antibodies target myelin, the protective layer around nerves.  Auto-antibodies attach directly to a target tissue triggering an immune response, since the immune system thinks the body's own tissue is the threat.  

The immune system's normal function is to recognise and protect against foreign pathogens (eg viruses, bacteria and other environmental threats) by using a diverse repertoire of immune receptors. The majority of these immune receptors recognise 'self' body cells and are silenced or eliminated in a process called Immune tolerance.  Therefore the Immune system has the ability to distinguish 'self' body cells and tissues  from 'non-self' foreign invaders that must be destroyed.  Immune tolerance is a state of unresponsiveness of the immune system to self tissue i.e. our immune system must not attack our own tissues.   A combination of genetic and environmental triggers may cause the immune system to become dysfunctional.  This is called a loss of immune tolerance, examples where immune tolerance can become dysfunctional is:

1) Oral tolerance - the immune system reacts against different dietary food proteins causing food sensitivities 

2) Chemical tolerance - the immune system reacts to soaps, detergents or even smells

3) Self tolerance - the immune system reacts to the body's own tissues ie Autoimmunity

Restoring the tolerant state is a crucial goal in managing Autoimmune diseases.  Loss of immune tolerance and Autoimmunity can eventually cause a weakened immune response (low white blood cells) since the body is constantly attacking itself immune exhaustion may occur leading to more chronicity of infections and bacteria and yeast overgrowth; a vicious cycle. 

Immune tolerance is a complex immunological process.  Immune cells implicated in Autoimmunity, such as self reactive T cells and B cells, are kept in check by some of the following and evidence based research continues to become available on how clinicians can therapeutically target these immune components to restore tolerance:

  • Regulatory T Cells (a crucial T cell in maintaining tolerance)

  • Anergy (Inactivation of proliferative T and B Immune Cells)

  • Inhibitory Receptors (cell surface molecules sending inhibitory signals)

  • Immunoregulatory cytokines (cell signalling proteins secreted by immune cells)

  • Tolerogenic dendritic cells (innate immune cells that stimulate T and B cells)

'ORGAN SPECIFIC' V 'SYSTEMIC' AUTOIMMUNITY

Clinical manifestations of Autoimmunity are varied and will depend on the biology of the individual including the status of their immune system at a point in time.

Conditions where immune responses are directed against a single organ or tissue, result in organ-specific disease.  For example, type 1 diabetes, where autoreactive T cells and auto-antibodies target β cells of the pancreatic islets.


Conditions in which Autoimmune reactions are against widespread antigens, result in systemic disease . The best example of systemic autoimmune disease is Systemic Lupus Erythematosus, in which a diversity of antibodies are directed against DNA, platelets, red cells, and protein-phospholipid complexes result in widespread lesions through the body.

Antibodies

MULTIPLE AUTOIMMUNE SYNDROME

Since Autoimmunity reflects a dysregulated immune system, the presence of more than one disorder is not uncommon.   Multiple immune-mediated disorders may be present simultaneously or sequentially during the different stages of disease process, this is called poly-autoimmunity.  When three or more coexist, this condition is called Multiple Autoimmune Syndrome and several autoantibodies may exist.  

If Autoimmunity is left unmanaged, it can damage other tissues through mechanisms such as molecular mimicry, bystander effect and epitope spreading.  Quite often the cause that started the Autoimmunity (eg a virus) may not be what is continuing the disease process (eg. stress).  This is why learning how to manage Autoimmune flares is important. 

COMMON AUTOIMMUNE DISEASES

  • Hashimotos Thyroiditis

  • Rheumatoid Arthritis

  • Celiac Disease

  • Graves Disease

  • Diabetes Melitus Type 1

  • Psoriasis

  • System Lupus Erythematosus

  • Inflammatory Bowel Disease

  • Vitiligo

  • Sjogren's Syndrome

  • Addison's Disease

Autoantibodies

SYSTEMIC INFLAMMATION

A major component of Autoimmunity when the immune system throughout the body becomes upregulated and hyper-responsive, is systemic inflammation .  This may have many different effects across the body.  For example:

  • Systemic Inflammation which affects the brain may cause symptoms of 'brain fog' or cognitive decline. 

  • Systemic inflammation may contribute to a breaking down of immune barriers across the body such as gut and lung barriers, causing sensitivities to foods or air particles. 

  • Systemic inflammation in muscles can cause aches or fatigue and swelling in joints, abdomen and other areas can also be a problem. 

  • Also during systemic inflammation, mitochondria may become inefficient, so the body can't make as much ATP energy causing more fatigue. 

Systemic inflammation and Autoimmunity may loop into a vicious cycle, hence addressing inflammation can be a key clinical target in Autoimmunity.

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