Recently, there has been a lot of talk and even hype about the immune system. Certainly, the global pandemic caused by COVID-19, or coronavirus, has heightened everyone’s awareness of immunity. And, of course, whenever something is constantly in the news, inaccurate information often gets shared on the internet and social media about how you can “boost” your immune system to help you fight off the next invader lurking around the corner.
Stepping back for a moment, though, if you have type 1 diabetes, you might be curious about your own immune system as it related to diabetes. After all, type 1 diabetes is called an autoimmune condition, whereas type 2 diabetes is more commonly considered to be a consequence of insulin resistance. What triggers the immune system to go haywire, leading to type 1 diabetes?
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What your immune system does
You don’t need to be an immunologist to understand how your immune system works. For the most part, your immune system has one job, and that’s to prevent infection. It’s like having your own Secret Service detail, 24/7.
Your immune system is clever in that it can distinguish between normal, healthy cells and unhealthy cells by recognizing a variety of “danger” cues called danger-associated molecular patterns (DAMPs). Examples of unhealthy cells are cells that might be damaged due to an infection, a sunburn or cancer. Microbes, such as viruses, bacteria and fungi can also damage cells by releasing another set of signals called pathogen-associated molecular patterns (PAMPs).
Basically, these DAMP and PAMP signals activate the immune system to respond. If one’s immune system isn’t working as it should, problems occur, such as an infection. Likewise, if one’s immune system is activated when there’s no need, or it goes into overdrive, it can cause issues such as allergic reactions or autoimmune disease.
Where is your immune system?
There’s no one organ that serves as your immune system. Instead, your immune system is made up of immune cells that are found in various places in the body.
Skin and mucous membranes
Your skin plays a dual role: it’s one of the first lines of defense, acting as a barrier, but it also contains immune cells and can secrete antimicrobial proteins. Your mucous membranes, which line your mouth, throat, nose, eyes and intestines, also serve as a barrier. Enzymes in your saliva and the tears in your eyes contain enzymes that break down cell walls in bacteria. Acids in your stomach not only digest food, they kill germs, as well.
Bone marrow contains stem cells that can morph into a variety of immune cells, including neutrophils, eosinophils, basophils, mast cells, monocytes, dendritic cells, and macrophages — these guys are the “first responders” when infection strikes. Other immune system cells include B cells, T cells, and NK (natural killer) cells, which are also called lymphocytes.
The lymphatic system is an intricate network of tissues and organs, including lymph nodes, the spleen, tonsils, adenoids and thymus gland, as well as lymph vessels that carry lymph throughout the body. Lymph is a fluid that contains white blood cells that fight off infection and disease. Lymph nodes filter out bacteria and viruses and destroy them. If you’ve ever noticed swelling in your neck or under your arms when you’re ill, that’s a sign your lymph nodes are doing their job.
How does your immune system work?
Most of us don’t think too much about our immune system except, perhaps, when it kicks into high gear or when it’s not working as it should. The immune system is activated when the body comes into contact with things that it doesn’t recognize. These “things” are called antigens, which are proteins found on the surfaces of viruses, bacteria and fungi. The antigens attach to receptors on immune cells, setting off a cascade of events. What’s amazing is that, as the body prepares to do battle, it also catalogs these antigens, storing the information in case the body comes into contact with that particular antigen in the future.
The immune system is divided into two sub-systems: the innate (non-specific) immune system and the adaptive (specific) immune system. Both are activated when the immune response triggers. The innate immune system draws upon natural killer cells and phagocytes to fight off the invaders. The adaptive immune system makes antibodies that are used to fight off germs the body has previously come into contact with.
Immune response to bacterial and viral infections
No doubt you’ve have had both bacterial and viral infections at some point in your life.
Common bacterial infections include:
· Upper respiratory infections
· Bacterial meningitis
· Eye infections
· Sinus infections
Some bacterial infections can be deadly, such as cholera, dysentery, tuberculosis and bubonic plague.
Bacteria enter the body in a number of ways: through contaminated food or drink, cuts, close contact with an infected person, or touching contaminated surfaces. When this happens, the body’s immune system is activated, reacting to the bacteria by increasing local blood flow (inflammation) and sending immune cells to attack and destroy the bacteria. Antibodies are also produced, attaching to the bacteria and killing them. Antibodies also inactivate toxins that bacteria produce.
More serious bacterial infections, such as strep throat, are treated with antibiotics that attack the bacterial walls, stopping them from multiplying. (Unfortunately, bacteria evolve and can become resistant to antibiotics). Vaccines are also available for some bacterial infections, such as tetanus, tuberculosis, diphtheria, cholera and typhoid.
Common viral infections include:
· The common cold
· Influenza (“flu”)
Less common viral infections are polio, Zika virus, HIV, H1N1 swine flu, Ebola and MERS. COVID-19, or novel coronavirus, is also a viral infection.
When a virus invades the body, it attaches to and enters a cell, releasing its genetic material. This forces the cell to replicate, helping the virus multiply. The cell eventually dies, releasing more virus that affects even more cells. Some viruses don’t kill cells, but instead change how they function, causing them to replicate out of control. This process may lead to cancer.
Viruses are sneaky in that they can go dormant and lie in wait, causing illness at a later time. A good example of this is the varicella-zoster virus, which causes chicken pox. Once you’ve had chicken pox, the virus lies inactive in nerve tissue. But years later, it can reactivate as shingles.
The body’s innate and adaptive immune systems are activated when a virus invades. Immune system cells work to kill cells infected with the virus. Viruses released from infected cells may be inactivated by antibodies as a result of a prior infection or a vaccine.
Viruses can adapt, which means that some immunizations, such as the flu, must change every season. And for other viral diseases, coming up with a vaccine is nearly impossible: by the time the vaccine has been developed, the virus has already changed, rendering the vaccine useless. Speaking of useless, antibiotics are useless against viral infections (which is why you shouldn’t ask your doctor for an antibiotic when you have a cold). There are antiviral drugs that work against some viral diseases, such as influenza, HIV and hepatitis B and C.
What happens in autoimmune disorders?
According to MedlinePlus, “An autoimmune disorder occurs when the body’s immune system attacks and destroys healthy body tissue by mistake.” If you have an autoimmune disorder, your immune system gets confused: it can’t distinguish between healthy tissue and potentially harmful antigens. So, the body launches an attack that, unfortunately, destroys healthy tissue. Researchers aren’t really sure what causes autoimmune disorders. It could be bacteria, viruses, drugs or even genes that make people more prone to them. The skin, joints, muscles, blood vessels and endocrine glands (e.g., pancreas, thyroid) are typically affected. It’s also common for someone to have more than one autoimmune disorder. Common autoimmune disorders include:
· Type 1 diabetes
· Multiple sclerosis
· Celiac disease
· Graves disease
· Rheumatoid arthritis
Researchers believe that type 1 diabetes is caused by genes and environmental factors, including viruses. The thinking is that if the virus has the same antigens as beta cells (the cells that produce insulin in the pancreas), the T cells that make antibodies actually turn against the beta cells and destroy them, which can take several years. Viruses thought to possibly instigate this process include:
· B4 strain of the coxsackie B virus (this virus can cause gastrointestinal problems and myocarditis)
· German measles
Research is ongoing to help determine the exact causes of type 1 diabetes, as well as how to prevent and slow the disease. TrialNet is one such study. For more information, visit www.trialnet.org.
Does having type 1 diabetes make you more prone to developing infections?
The short answer: No. However, having type 1 diabetes does make it more likely that, if you do become ill, you are at higher risk of developing serious complications, such as DKA (diabetic ketoacidosis). That’s why it’s so important to have a sick-day plan in place. And do the best you can to keep your glucose levels within your target range.
In a future piece, we’ll look at ways to help you support your immune system. Because everyone needs support now and then!