What Is Immunosenescence?
Aging is a process that we can’t reverse. As we age, the body gradually deteriorates. It doesn’t only do it on the outside, with the appearance of wrinkles on the skin, but also on the inside. Today we’re going to talk about immunosenescence, also known as aging of the immune system.
After a certain age, the deterioration of the body’s immune functions begins. It occurs both at the level of natural immunity and acquired immunity. Its consequences are felt in different ways, especially when contracting infections or diseases. Let’s see what the experts say about it.
The fact is that immunosenescence is a problem that researchers have been aware of for several decades. It’s described as the progressive deterioration of the immune system as a result of the body’s natural aging. The hidden mechanisms that create this degeneration aren’t exactly known, although the evidence points to a chronic involution of the thymus.
Other specialists believe that the causes of immunosenescence are multifactorial, revolving around genetic, environmental, and lifestyle factors. Be that as it may, it’s a real problem that we all must face during the last decades of life.
Although it’s true that the impact on the acquired immune system is greater, studies agree that the innate immune system also suffers a significant loss. Let’s see what aspects are compromised due to the aging of the immune system.
Innate immune system
It’s also known as the natural or specific immune system. It basically decides the protection we’re born with that then serves as protection against antigens. Taking only the most important elements as a starting point, these are the aspects of the system that are affected during immunosenescence:
- Neutrophils: Alteration of apoptosis (programmed cell death) and ROS production (reactive oxygen species).
- Monocytes: Their phagocytic activity (the process in which certain compounds or cells are captured and degraded) and MHCII (class II major histocompatibility complex) decrease.
- Macrophages and dendritic cells: The number of macrophages in the bone marrow decreases and the number of dendritic cells in the blood decreases. Langerhans cells also decrease.
- Pattern Recognizing Receptors (PRRs): Pattern recognition receptors (PTTs) are disrupted. As a consequence, antigen capture is decreased.
- NK cells: Their volume increases, although their cytotoxicity decreases at the same time.
- NKT lymphocytes: There are alterations, most of them related to their decrease.
- Thymus: Although its size doesn’t vary, it does experience several internal changes. There’s a reduction in the number of thymocytes and stromal cells.
Acquired immune system
This is also known as the adaptive immune system. This is the part of the system that’s acquired after birth, in principle after interaction with an antigen. In this case, the most affected areas are the following:
- T cells: The number of naive T cells decreases, thereby reducing immunosurveillance and the response to new pathogens entering the body.
- B cells: There’s a decrease in naive B cells. As a result, the antibody response decreases.
- Cytokines: Some increase (IL-1, IL-6 and IL-8), while others decrease (IL-2 and IFNy). This results in a predisposition to chronic inflammatory states and hypersensitivity (to allergies, for example).
- Stem cells: The composition of stem cells changes from that of young patients. It decreases its activity, but increases its presence in the bone marrow.
As we can see, the alterations are general during the immunosenescence process. It affects the most important parts of the immune system, which generates a series of consequences in the short, medium, and long term. Let’s have a look at this in a bit more detail in the next section.
The consequences of immunosenescence
As Johns Hopkins Medicine reminds us, the aging of the immune system produces an increased risk of reactivation of latent viruses. It’s for this reason that, during the last decades of life, there’s an increase in reported cases of the varicella-zoster virus, Epstein-Barr virus, herpes simplex virus and cytomegalovirus.
These viruses remain dormant in the body after an infection during childhood or adolescence. Due to the alterations that occur in the functioning of the immune system, they appear as soon as the effectiveness of the protection decreases. Other consequences related to this natural process are the following:
- A lower response to vaccination
- More acute episodes of inflammation
- Persistent infections
- Slower wound healing
Researchers also point out that immunosenescence is directly related to an increased chance of developing cancer. Again, this partially explains why the majority of reports occur in people over the age of 50.
What can we do to avoid immunosenescence?
Since the mechanisms that regulate it completely aren’t known, specialists aren’t sure if immunosenescence can be prevented. Some of its problems are thought to be reversible, such as the number of naïve T cells and immunoglobulin-producing B cells.
Evidence suggests that gene or combination therapy may be effective in restoring part or all of the immune system’s function. Thymus transplantation may be an option in certain cases. As for the things you can do to avoid it, we know that nutrition can play a leading role.
Indeed, there’s enough evidence in this regard to confirm that a balanced diet can delay the effects of immunosenescence. The nutritional approach varies according to each person, although, in general, studies indicate that vitamins, minerals and probiotics have a positive impact in this regard.
Other things that you can include in your routine to prevent aging of the immune system are the following:
- Reducing episodes of stress or tension
- Doing physical activity
- Avoiding a sedentary lifestyle
- Keeping a healthy weight
- Keeping diagnosed diseases under control
In general terms, a healthy life can work in your favor when it comes to reducing the deterioration of these functions. Although you can’t control the genetic predisposition you have in this regard, if you include these tips in your routine you will tip the balance in your favor.