Your Immune System And Asthma: What To Know
Researchers now understand asthma is a disease associated with chronic underlying airway inflammation. And this inflammation is caused by an abnormal immune response. Considering this truth, I thought it would be neat to delve into a simple question: What is the immune system anyway? Here’s what to know.
While your respiratory system makes it so you can breathe, your immune system makes it so foreign pathogens (like viruses) and irritants (like chemicals) stay out of your lungs. It involves a series of genes, proteins, cells, tissues, and organs.
To make this simple, we will begin by only speaking of pathogens. Before reading on, you may benefit from reading my post, "Airway Anatomy 101."
Innate (nonspecific) immune system
It’s also referred to as the nonspecific immune system because it’s nonspecific to any pathogens. It will immediately respond to any pathogens even though you may never have been exposed to them before. Its job is to act as the first line of defense against these pathogens; to keep them out of your body; to keep them out of your lungs when they get in.1
Just looking at the respiratory system, hairs in your nose are the first line of defense. They act to filter inhaled pathogens. When pathogens get in and invade cells lining airways (epithelial cells), they release chemicals that make other cells aware of the invasion. Goblet cells lining airway secrete mucus to trap these pathogens and ball them up. Cilia on the surfaces of epithelial cells move balled up pathogens to your upper airway to be swallowed and incinerated by stomach juices.
Mast cells are randomly scattered throughout your airways. They are squeezed tightly between airway epithelial cells, airway smooth muscle cells, and airway connective tissues. They are most likely to exist near blood vessels.2 When exposed to pathogens they release chemicals into the bloodstream. Some of these chemicals cause airway inflammation. Others travel through the bloodstream to activate cells of the adaptive immune system.
Adaptive (specific) immune system
Once a pathogen gets past the innate immune system, it’s time for the adaptive immune system to take over. This is when your immune system develops a specific response to certain pathogens, such as the Rhinovirus. It has to be exposed to the pathogen first, and over time it learns to recognize it. You become sensitized to it.
Once you are sensitized to a pathogen, your immune system will recognize that pathogen during subsequent exposures to that pathogen. When this happens, your immune system instigates a full-fledged war against it. Part of this war involves releasing chemicals that cause airway inflammation. This inflammation is meant to trap, kill, and help you spit out the pathogen. This inflammation is what causes cold symptoms.
Flaws in certain genes (asthma genes) sometimes tell cells of the adaptive immune system to recognize harmless substances (like allergens) as harmful. This is what causes asthma. I will delve further into this topic in upcoming posts. So, stay tuned!
This is a normal response of the immune system to trap, kill, and remove foreign invaders. It’s a natural response to cells that have been infected or cells that are injured or damaged. However, an abnormal immune response, due to asthma genes, tells immune cells to initiate the inflammatory response when exposed to harmless substances like dust mites.
The characteristics of acute inflammation are:3,4
- Rubor (redness)
- Calor (heat)
- Tumor (swelling)
- Dolor (pain)
These characteristics are what cause your cold symptoms. They also contribute to allergy and asthma symptoms. This is described in more detail below.
What causes inflammation?
Just to give one example, Th2 cells release a cytokine called Leukotriene 13 IL13, which directly causes airway inflammation. It does this by dilating blood vessels in the area and increasing the permeability of the cell wall. This allows small amounts of blood to seep out of the blood vessels into interstitial spaces (the spaces between cells), and this is just one cause of airway inflammation.
What symptoms are caused by inflammation of your upper airways?
This is most likely to occur when your airways become infected by a respiratory virus or common allergen. Airway inflammation irritates goblet cells to cause increased secretions (runny and stuffy nose, post nasal drip, cough), It irritates nerve endings to cause that irritating, itchy feeling (scratchy throat, itchy nose). These are your typical cold symptoms. They are certainly annoying, but they are a sign that your adaptive immune system is doing what it’s supposed to do.
What symptoms are caused by inflammation of your lower airways? This inflammation irritates goblet cells in the area to cause an increase in mucus production (hypersecretion). It irritates smooth muscles in the area to cause them to spasm and squeeze airways (bronchoconstriction), and it irritates nerve endings in the area to cause chest tightness or pressure (pain).
What is the purpose of inflammation?
The purpose is to trap, kill, and move pathogens to your upper airway so they can be swallowed and devoured by stomach juices. It’s normal when it occurs in response to pathogens. It’s abnormal when it occurs in response to harmless substances like dust mites.
What to make of all this?
The immune system involves a whole lot more than what I can possibly expound upon in one post. I just wanted to share this basic information with you to give you an idea of what your immune system involves. In upcoming posts I will show you what can go wrong, and how both your innate and adaptive immunity can work together to cause asthma and asthma symptoms.
Have you ever gotten "moon face" as a side effect of prednisone?