The Importance of Immunity

How does our immune system play a role in our overall healthspan and cellular health? Let's dive in.

We know that a strong immune system is the key to staying overall healthy and preventing pesky colds. The reality is, our immune system is intricately designed, and like all our systems, connected to our cells and overall health.  

Immunity is the term used to describe your body’s ability to mount an immune response and protect bodily tissue from pathogens and trauma. Your immune system is responsible for activating an immune response, which can be broken down into innate, adaptive, and passive responses – let's go over them. 

Your innate immunity is what you are born with. This type of immunity is the body’s first line of defense and is activated in response to pathogens or any unknown the body encounters. It’s sort of like blanket immunity—similar to a bucket of water used to put out a campfire. Generally effective, but only on small, contained fires. Sometimes, you need a more strategic approach. 

Once your innate immune system is activated, your adaptive immunity begins to set in. The adaptive immune response involves the production of small proteins called antibodies that further recruits more immune cells to attack pathogens during infection.  

What’s super interesting is, these antibodies form a cellular memory for your immune system, which your passive immunity uses to survey the body’s vessels for reinfection events. Adaptive and passive immunity is why you typically only experience certain infections once, like chicken pox. This is because the antibodies produced by your body are powerful enough to signal the body if chicken pox virus reinfects you, protecting you from an active breakout of the virus in the future. 

An overview of immune system biology 

White blood cells play a pivotal role in our immune response. Phagocytes are a type of leukocyte that are primarily responsible for engulfing and removing cellular debris. They essentially “eat” the junk in your body and keeps things operating smoothly -- this is nothing new to us, and something we've covered quite a bit. 

Neutrophils are another type of leukocyte that specifically target bacteria, designed with functionality that can fight off bacterial infections. Due to this, doctors often take a neutrophil count from a blood sample to confirm or rule out bacterial infection. 

Lymphocytes are a major player in the immune response and are yet another type of leukocyte. These cells are primarily involved in labeling pathogens for destruction and for making antibodies—those cellular memory signals mentioned earlier. As such, lymphocytes are involved in adaptive and passive immunity. They’re produced in the bone marrow, and from there, they eventually mature into one of two specific types of lymphocytes. 

• T lymphocytes: the memory bank of your immune system, T lymphocytes take those antibodies produced by B lymphocytes and memorize them. From there, they passively survey the body for possible reinfection by pathogens. 

Macrophages are another type of white blood cell responsible for destroying microorganisms, clearing dead cells, and activating other cells of the immune system. In the central nervous system (CNS), macrophage are better known as microglia. Microglia are resident immune cells of the CNS and play key roles in both immune defense mechanisms and behavior (more on that here). An important role of macrophages is to signal inflammatory responses by releasing small proteins called cytokines. Pro-inflammatory cytokines are typically involved in recruiting inflammatory compounds and mediate bodily responses like wound healing and feeling feverish.  

Anti-inflammatory cytokines are like the brakes of the immune system—they increase activity when the body no longer needs inflammation to fight off pathogens and heal wounds, and are typically released shortly after pro-inflammatory cytokines begin to circulate. 

Mast cells, which are responsible for allergic reactions, and monocytes, which transform into macrophages and dendritic cells once an invader enters the system (i.e., bacteria or virus), are also important white blood cells. Dendritic cells are responsible for linking innate and adaptive immunity together by sensing markers on the surface of pathogens (antigens) and notifying T lymphocytes of their presence.  

Cellular health and its relation to immune response

As you can imagine, good cellular health is imperative to a functioning immune system, given the various types of cells responsible for coordinating an effective immune response and keeping you healthy. Most of us know that we can "boost" our immune system and keep it going strong with basics like Vitamin C from citrus fruit, ginger, and garlic, to name a few. But there's lots of intracellular activity happening beneath the surface when it comes to a true immune response.

During an immune response, immune cells rapidly prioritize glucose as the main energy resource over other types of energy. This shift in resource priority is known as the Warburg effect. It’s thought that this occurs because glycolysis, the cellular pathway that breaks glucose down into a carbon energy source, is linked to activation of certain genes responsible for increasing T lymphocyte activity. This is primarily why maintaining cellular energetics is important to cellular health because without glucose, T cell activation may become impacted.  

At the same time, it is incredibly important to make sure energy systems within the cell are primed and ready to mount an immune response because of the amount of work that has to be done to produce the energy required by immune cells. In other words, your mitochondria need to be kept in an optimal state so they can keep up with the energy demand of an immune response. 

Beyond energetics, a faulty immune response is a trigger for many long-term health problems. For example, if you mount an immune response, and all systems proceed as usual, but phagocytes are unable to sufficiently remove the junk from your system, this can cause long-term changes in your immune function. This is because cellular debris and viral particles can actually stimulate the immune response, and if this is left untouched for long periods of time, or if viral particles and debris accumulate, we’ve got a recipe for chronic inflammation -- a well-known contributor to age-related disease. 

Cell signaling by cytokines is incredibly important as the mediators of the pro and anti-inflammatory immune responses. If anti-inflammatory signaling goes awry, we could end up with a prolonged pro-inflammatory response, which as mentioned, provides a basis for chronic inflammation. On the other hand, if anti-inflammatory responses are overactive, we end up with a suppressed immune system, which is also not good; especially when it comes to fighting off pathogens and healing from trauma.  

Finding that delicate balance is essential to maintaining a proper immune response that fluctuates between pro- and anti-inflammatory signals. Without proper signaling, which can arise from malfunctioning protein synthesis or the presence of oxidizing compounds, among other things, we set ourselves up for quite the battle with both short- and long-term diseases.  

To put it simply, cellular health contributes to a robust, functioning body, and a healthy immune system is very much a part of that! 

Does a strong immune system improve my healthspan?

Where lifespan is the number of years lived, healthspan is the number of years lived in a healthy state with minimal disease. Healthspan has become an important concept in recent years because while yeah, would be nice to live a long life, wouldn’t be even better to live a long, healthy life?  

A long lifespan doesn’t necessarily equate to good quality of life, especially if a person is riddled with age-related diseases, chronic inflammation and pain, limiting their day-to-day capabilities. On the other hand, a longer healthspan provides the capacity to live well into older age without much impact on their ability to take part in daily activities. In other words, a good healthspan warrants you the freedom to continue enjoying life to the fullest well into your later years. 

Evidence supports the notion that high levels of inflammation over many years (in other words, “chronic inflammation”) contributes to several different diseases like diabetes, cardiovascular issues, cancer, kidney disease, and so on.  

Chronic inflammation happens when the cellular processes (i.e., signaling) that control the immune response become defective. For example, if the problem is rooted in cell signaling errors, this is likely an issue in maintaining a balance between pro- and anti-inflammatory cytokine responses. As mentioned earlier, if anti-inflammatory cytokines lose their ability to suppress pro-inflammatory cytokines, this can trigger a self-perpetuating cycle of inflammation and in turn, develop into chronically elevated levels of inflammation.  

Individuals tend to develop a low-grade pro-inflammatory state as they age, thought to be the result of defective anti-inflammatory responses. This low-grade inflammation can not only change in how the immune system functions, but it also impacts cognition, motor performance, and metabolism. So, by supporting your immune system throughout the lifespan, you can indirectly support your healthspan by preserving cognitive function, muscle performance, and metabolic processes. 

Simply put—yes, maintaining a strong immune system seemingly provides you with the protection necessary to avoid chronic inflammation and long-term issues associated with various viruses, diseases, etc. And in the end, avoiding chronic inflammation can reduce the potential of developing age-related diseases. 

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