The Gut-Thyroid Connection: The Rise of Hashimoto’s & Autoimmunity
The story of autoimmunity and how it develops has many characters and many plot twists. Although the primary dysfunction rests within the immune system, that dysfunction is able to manifest from concomitant issues in other systems – most notably the digestive system. As you are well aware, consequences of autoimmunity impact the entire body.
First, let?s start with a story of how your immune system learns to be.
The job of the immune system is simple: Find and kill anything that is not ?self?. It is singular and relentless in this focus. It does a good job, otherwise, we would all succumb to infectious disease or injury in hours to days.
Your nutrition and friendly bacteria are not ?you?, however. There is a conundrum. The immune system must learn to tolerate things that are not-self yet support the self, while at the same time seeking and destroying bad guys.
When you are a tiny baby, your immune system goes to T Cell University – the thymus gland. Just an innocuous bit of tissue behind the breastbone, this is the location where newly budding immune cell lines learn to ?tolerate? and not destroy your own cells, the foods you must eat and the friendly bacteria that are colonizing your body.
Immune cells who show any activity against these things are culled and not allowed to be. Your current immune system is the descendant of the successful immune cells lines who showed good tolerance to the things that will support you – food and friendly bacteria and your own human cells. Wonderful graduates!
This process that the immune system undergoes is called tolerization. This is an important chapter in our autoimmune story, because tolerization is lost, at least partially, in autoimmunity.
The vast majority of your immune system resides in the gastrointestinal system in specialized tissue called GALT and MALT (gut- and mucosa- associated lymphoid tissue, respectively). This tissue is in extremely close proximity to your small intestine. It is embedded below the small intestine.
The small intestine is the next major character in your tale of autoimmunity, because it acts as the interface between your immune system and everything that you eat and swallow or otherwise gets in your belly.
The integrity of the lining of your small intestine is of utmost importance because it acts like a gatekeeper or screen for the immune system.
The lining of the small intestine – also called the brush border – is a very unique structure.
The lining of the small intestine is but one cell layer thick. The cells stand closely together, touching, like a row of soldiers. They sit so closely together that there is a structure – called a desmosome – that buttons them together. This buttoning-up equates good integrity and a balanced immune system. Nutritive particles are absorbed in the brush border as they move on down your GI tract.
One of the first steps to autoimmunity is a defect or blip in the integrity of this lining. Transient losses of integrity are actually normal – when we get sick or when we work out hard, our linings actually become more permeable to promote better immune response and healing. This increased permeability is carefully controlled and resolves on its own with no help or input from us.
Where we run into trouble is when permeability goes chronic. When it is unchecked and uncompensated and not brought in to heel.
Increased permeability means that the interface between the immune system and the external world of food and bacteria and ?self? cells has been breached. A consequence of that is an unchaperoned interaction between these things.
It doesn?t go very well. In fact, the immune system becomes provoked. It releases inflammatory compounds and antibodies as it runs into particles it doesn?t think should be there. This does two things – it maintains the permeability of the lining of the small intestine by keeping the desmosomes unbuttoned and it calls more immune cells to the area, who release even more inflammatory compounds and antibodies.
Over time – and we aren?t really sure how much time – if left unchecked, tolerization is lost. Our immune cells forget that they are not supposed to be reacting to food, to friendly bacteria, and to our own cells. They forget, and then they react.
When the immune system makes antibody against your own tissue – your thyroid, for example – it is marking that for destruction. This is the heart of autoimmunity. The immune system begins its attack, and we begin to feel horrible. Even more horrible than the events leading up to it, which can make us feel pretty bad too.
How can it do that? Proteins are redundant – there are patterns and similarities between the proteins we eat and the proteins of our own body. The body uses the templates of the proteins of food particles – most famously gluten – to make antibody against self. This is called molecular mimicry.
Accumulating food sensitivities (?I used to be able to eat that, now I can?t!), increased environmental allergies, water retention, brain fog, bowel changes, odd pains through the joints and muscles are harbingers that this process is going on. The lining of the small intestine is irritated, the immune system is being provoked, and the body is unable to compensate and bring it all back in to balance.
That?s when autoimmune markers begin to go up, whether it is a general screening test like ANA (anti-nuclear antibodies) or if it is specific to a tissue like anti-TG or anti-TPO (thyroglobulin and thyroid peroxidase, with autoimmune markers used to diagnose Hashimoto?s or Grave?s disease). Once the autoimmune process is established, you become more likely to get another autoimmune condition than someone without any, because of the climate of the over provoked immune system.
To begin to back out of this mess, we must return to the scene of the crime: the lining of the small intestine.
Remember, it is the unchecked irritation of the lining that creates a dysfunctional immune response and a breached integrity that continues to feed the breach and the immune response both.
Eating foods that you are sensitive to or are inherently provocative to the immune system without balancing them with less-inflammatory foods; an inability to adequately break down the foods you are eating, a less-than-robust or frankly infected microbiome or gastrointestinal tract (SIBO – small intestine bacterial overgrowth, dysbiosis, candida infection, parasites), binge drinking, NSAIDs, high pH of the gut from use of acid blockers & excessive alkaline water, chronic stress including being under slept and having no down time all contribute to the irritation of the lining of the small intestine, and thus are key factors in the healing of not simply the increased permeability of the gut but the entire autoimmune process.
Each of these factors must be addressed to break the feed-forward cycle of dysfunction and get your immune system back on the rails.