Some diseases, especially the ones that develop in the more mature amongst us, are linked to an aging immune system, and develop with a progress in age.
It is a long list to add all the immune conditions that we are discovering more about daily. Though the science and the study of autoimmunity grows in leaps and bounds daily, it is the area of age related immune disorders where we are the most pressed to find answers to preventative healthcare for the aging and elderly.
Aging is a complex process where many functions in the body, psychological, biological, and sociological, all undergo changes, big and small.
Dr. Denham Harman, former Professor emeritus at the University of Nebraska Medical Center is known as the "father of the free radical theory of aging".
His theory of free-radical damage and mitochondrial theory claims that aging is characterized, respectively, by free radical-induced DNA damage and mutations, as well as by impairment and disruption of cellular processes, and by the loss of the mitochondrial ability to produce and stock energy.
Why the increase in age-related autoimmunity?
Quite simply, we are getting older as a population, worldwide. We are healthier in our younger years, and this well-looked after health has enabled us to live longer. Your average Baby Boomer is still healthier well beyond retirement age, and expected to live into their 80s or 90s.
With this longer life, comes the risk of disease.
Life expectancy for the average North American for those born in 2018, ranges in the 80 year mark. In Canada, the average life expectancy was 80 years for males and 84 years for females in 2018.
This places huge pressure on healthcare systems to support an aging population, many of whom are suffering from debilitating, but not necessarily deadly conditions. The nature of autoimmune disorders is usually chronic and slow acting, meaning an older sickly population in need of regular, repetitive treatment.
Macrophages and T Cells
T-lymphosytes or killer T cells are like foot soldiers in the body's army, sent to hunt down and destroy pathogenic cells, or any germ that they encounter. Helper T cells are the sergeants and generals which co-ordinate and organized the attack on the invaders.
Macrophages are 'large' phagocytes which are either stationary or mobile white blood cells sent to the location of infection in the body.
The combined effect of the reduced effectiveness of these two important components of the immune system impacts on the effectiveness of the whole system, and the body.
The older we get, the less effective the immune system gets. We have discovered a few factors that impact immunity and the Immune System. The following things happen to an aging immune system, and increase our chances of developing cancer, leukemia or an autoimmune condition:
- The immune system becomes worse or less able to identify foreign antigens and differentiate them from its own cells.
- The bacteria fighting macrophages which usually ingest foreign invaders and bacteria start to slow down in their action, sometimes not recognizing the threat of the pathogen, and allowing it to take hold in your body.
- The immune systems T Cells, which are about the same in number as younger immune systems, respond slower to foreign antigens.
- An aging immune system has fewer specialized proteins to respond to bacteria.
- There are just fewer white blood cells geared to respond to new antigens, and therefore when an older immune system fights a new antigen, the body is less able to mark it and defend against it.
- Antibodies become less able to attach to the antigen. This change may partly explain why pneumonia, influenza, infective endocarditis, and tetanus are more common and more lethal among older people
- Vaccines are also less effective in older people because of the issue of slow identification and slower attachment to antigens
The Aging Immune System
With the progress of age your immune system, both the innate immune system, and the adaptive part of the immune system, along with other organs and tissues, undergoes multiple restructuring and remodeling. The adaptive immune system undergoes the most change, and because of this, it is more likely to mis-identify and incorrectly target healthy parts of the body.
Referred to as “immunosenescence,” “immunopause,” or “immune dysregulation” it includes three maladaptive events: (a) a reduction in immune response, (b) an increase in the inflammatory and oxidation background (inflammaging - a term coined by Dr. Claudio Franceschi and oxi-inflammaging), and (c) a production and release of autoantibodies.
Among the elderly, immunosenescence has been associated with an increased in blood tumors and lymphomas due to immune deficiency and immune surveillance changes.
Age-related changes at the level of the immune system in lymphoid populations with age are selective; in other words, not all subpopulations are equally affected: the degree of changes can vary between people and can occur at different ages.
Some age related autoimmune conditions are:
- Cancers – all cancers are in some form, a response or lack thereof, of the immune system.
- Rheumatoid arthritis – where the immune system produces antibodies that attach to the linings of joints. Immune system cells then attack the joints, causing inflammation, swelling, and pain.
- Systemic lupus erythematosus (lupus). People with lupus develop autoimmune antibodies that can attach to tissues throughout the body. The joints, lungs, blood cells, nerves, and kidneys are commonly affected in lupus.
- Inflammatory bowel disease (IBD). The immune system identifies the lining of the gut as pathogenic resulting in episodes of diarrhea, rectal bleeding, urgent bowel movements, abdominal pain, fever, and weight loss.
- Ulcerative colitis and Crohn's disease are the two major forms of Inflammatory Bowel Disease.
- Multiple sclerosis – where the immune system attacks nerve cells, causing pain, blindness, weakness, poor coordination, and muscle spasms.
- Type 1 diabetes mellitus. Immune system antibodies attack and destroy insulin-producing cells in the pancreas.
- Guillain-Barre syndrome. The immune system attacks the nerves controlling muscles in the legs and sometimes the arms and upper body. Weakness results, which can sometimes be severe.
- Chronic inflammatory demyelinating polyneuropathy. Similar to Guillian-Barre, the immune system also attacks the nerves in CIDP, but symptoms last much longer.
- Psoriasis - overactive immune system blood cells called T-cells collect in the skin. The immune system activity stimulates skin cells to reproduce rapidly, producing scaly plaques on the skin.
- Graves' disease. The immune system produces antibodies that stimulate the thyroid gland to release excess amounts of thyroid hormone into the blood (hyperthyroidism).
- Hashimoto's thyroiditis - Antibodies produced by the immune system attack the thyroid gland, slowly destroying the cells that produce thyroid hormone. Low levels of thyroid hormone develop (hypothyroidism), usually over months to years. Symptoms include fatigue, constipation, weight gain, depression, dry skin, and sensitivity to cold.
- Myasthenia gravis. Antibodies bind to nerves and make them unable to stimulate muscles properly. Weakness that gets worse with activity is the main symptom of myasthenia gravis.
- Vasculitis. The immune system attacks and damages blood vessels in this group of autoimmune diseases. Vasculitis can affect any organ, so symptoms vary widely and can occur almost anywhere in the body.
All of these factors of aging resulting in impaired immune response, impact significantly on the body's ability to fight bacterial infections, viruses and cancers. So it is unfortunately true that as we age the risk of developing all, and especially age-related autoimmunity, increases.