Our immune system plays a crucial role in our health by protecting us from infections and diseases. The immune system is made up of specialized cells, proteins, tissues and organs and protects us every day from invading microorganisms and viruses. Various factors can...Impair or weaken the immune system, including stress, lack of sleep, poor diet, lack of exercise and poor hand hygiene. One question that doctors and scientists have been studying is whether the immune system weakens with age. We have summarized information from several studies and scientific articles in which researchers have examined the effects of aging on our immune system. Read on to find out how the immune system changes as we age.
How does the immune system change with age?
Dr. Peter J. Delves, professor at University College London, provides an overview of the effects of aging processes on the immune system in an article on the online portal merckmanuals.com.
This is why the immune system weakens with age:
- As we age, the immune system is less able to protect healthy cells and tissue from foreignersDifferentiate antigens. As a result, autoimmune diseases such as rheumatoid arthritis and lupus are more common.
- macrophages,which belong to the so-called phagocytes, no longer act as quickly as before against bacteria, cancer cells and other antigens. This slowdown could be a reason why cancer is more common in older people.
- TheThymus, located behind the breastbone, is an important organ of the lymphatic system and one of the most important parts of the immune system. T cells mature from stem cells in the thymus. After puberty, however, the thymus begins to degenerate until it has lost around 85 percent of its size by adulthood.
- T cells respondno longer react so quickly to antigens, that is, to unwanted intruders, even those they have already encountered. Although the number of T cells does not decrease with age, T cell immune defense function decreases.
- There arefewer white blood cells, which are able to react to new antigens. So when older people encounter a new antigen, the body cannot remember it and defend itself against it.
- Older people produce smaller amountsComplement proteins, which serve to defend against microorganisms (e.g. bacteria, fungi, parasites) in response to bacterial infections.
- Although the amount of antibodies produced in response to an antigen remains approximately the same, the antibodies canno longer attach to the antigen as well. This change may be part of the reason why diseases such as flu, pneumonia and tetanus are more common and fatal in older people. This also explains why vaccines are less effective in older people and why it is therefore important that older people receive booster vaccinations.
A study by Austrian scientists found that, for example, the effectiveness of the tetanus vaccination decreases after the age of 40. By the age of 60, 16 percent of people vaccinated in the last five years were no longer fully protected. And traditional flu vaccines are only 30 to 40 percent effective in people age 65 and older.
These changes in immune function may contribute to older people being more susceptible to certain infections and cancers. Now we want to provide more information about some of these changes in the immune system as we age. Andin this articleWe have summarized the most important tips on how people aged 60 and over can strengthen their immune system.
Immune system in old age: T lymphocytes and the regression of the thymus
A report entitled“T cell ageing: Effects of age on development, survival & function”, published in the journal “Indian Council of Medical Research” in 2013, describes age-related decline in the immune system as a major health problem. The publication explains that “the role of T cells during aging is increasingly coming into focus due to their impact on overall immune responses.” Here are the key facts from the study.
The deterioration of the immune system in older people is often referred to as “immunosenescence.” A key factor in immunosenescence is the process of thymus involution, a gradual regression of the thymus with age. The thymus is the main gland of the immune system and is located behind the breastbone.
The main components of adaptive immunity are T and B lymphocytes. Precursors of T lymphocytes migrate from the bone marrow and colonize the thymus. All important events such as the development of functional lymphocytes and tolerance to self-antigens occur in the bone marrow for B cells and in the thymus for T cells. After maturation, these lymphocytes enter the bloodstream and develop appropriate immune responses against foreign antigens.
But after sexual maturity, this organ begins to shrink. By the age of 40, it has lost 80 percent of its size, making it less effective at converting white blood cells into fully functioning T cells. This regression of the thymus leads to a steady decline in the production of naive T cells, resulting in a limited immune repertoire for recognizing pathogens.
The thymus also becomes full of fat cells as we age. By age 45, long before most other organs have shown any signs of aging, nearly 80% of the thymus has already been converted to fat. While it's not clear where these fat cells come from or why they're there in the first place, the damage they cause is devastating. This explains why older people have weaker immune systems. But why the thymus gland stops functioning is still not completely clear.
Yale Scientific published an article in 2016 about a study by Vishwa Deep Dixit, professor of immunobiology at the Yale School of Medicine. He discovered a hormone that can contribute to reactivation after the thymus gland has degenerated. This hormone, known as fibroblast growth factor 21 (FGF21), can stimulate thymus function and prevent our immune system from weakening as we age. This finding may provide a promising treatment to boost immunity in the elderly and in cancer patients after bone marrow transplants. More research is needed before this hormone can be administered as a medication to improve thymus function. Dixit and his team are working to turn this into an effective therapy. If they are successful, the aging immune system could be rescued by a tiny hormone.
A healthy gut is the key to our well-being
Scientists at the Norwich BioScience Institute have conducted the first detailed study of how our intestinal tract changes as we age and how this affects our overall health. This information is important because “the gut plays a central role in programming our immune system and provides an effective barrier against bacteria that could make us sick. In particular, immune cells that colonize the intestine are particularly important for defending against bacterial pathogens.
Here are the key facts from the study:
- Changes in the structure and function of the intestinal barrier contribute to our immune system becoming weaker as we age, increasing the risk of infection and disease.
- The researchers found that as we age, the gut shows an increase in a specific immune system regulator called interleukin 6 (IL-6), which triggers inflammation.
- Inflammation is increasingly seen as an important factor in the aging process. The study results suggest that the intestine plays a crucial role in inflammatory processes.
- It is important that scientists develop methods to control inflammation to prevent colon cancer, inflammatory bowel disease, heart disease, diabetes and depression.
- If intestinal bacteria are responsible for changes in the intestinal barrier structure with age, it may be possible to counteract these changes with probiotics.
A scientific article entitled “Effectiveness of Probiotics for Preventing Infections in the Elderly: Systematic Review and Meta-Analysis” was published in “Nutrition Bulletin” in 2015. It takes into account the fact that older adults are more susceptible to infections, often with serious consequences. Studies suggest that probiotics play a role in preventing infections in older adults.
Here are the key facts from the study:
- Older people are more susceptible to infections than younger adults, with generally severe and atypical symptoms.
- Infections are a major cause of early mortality in older people.
- Elderly people who receive probiotic supplements for three months have a reduction in the average duration of an infection and a reduction in the incidence of infectious diseases, especially upper respiratory tract infections.
Stress weakens the immune system as we age
The American Institute of Stress (AIS) serves as a trusted source for all scientifically based information on stress management. On your site you report on how chronic stress affects seniors and how you can deal with it.
Here are the most important facts at a glance:
- A weak immune system can no longer effectively resist bacterial infections and respond to inflammation, leading to osteoporosis, arthritis, type 2 diabetes, cancer and dementia.
- Chronic stress is a cause of accelerated biological aging and therefore has a negative impact on the immune system and its function.
- Stress can greatly reduce the immune response to pneumonia in older people.
What do telomeres have to do with aging?
The telomeres are called and determine the life clock of every cellour biological age. As tiny components of DNA, they cover the chromosome ends like a kind of protective cap and thus prevent them from sticking together. But with every cell division, these structures shorten and accelerate the aging of the cell. If the telomeres are too short at some point, the cell dies. This is why shorter telomeres are also associated with increased biological age.
The enzyme telomerase is responsible for maintaining the correct telomere length. However, a number of studies show a link between shorter telomeres or reduced telomerase activity and a variety of diseases, including cancer, heart disease, osteoporosis and HIV infection.
A 2008 study suggests that reduced telomere length is also linked to chronic psychological stress and mood disorders. The researchers also found that exposure of T lymphocytes to theStresshormon Cortisolleads to a significant reduction in telomerase activity. The connection between psychological stress and shortened telomeres has also been documented in studies of mothers of chronically ill children and caregivers of patients with Alzheimer's disease. The complex interactions between the endocrine, nervous and immune systems can impact both mental and physical health.
References:
T cell ageing: Effects of age on development, survival & function
To Immunity and Beyond: Recruiting the Heroic Hormone that Rescues Aging Immune Systems
Reduced telomerase activity in human T lymphocytes exposed to cortisol
How our gut changes through our lifetimes, and how this determines our overall health
The American Institute of Stress
