Link between Hashimoto’s thyroiditis and lichen planus.

Today I am reviewing an article about my FAVORITE subject! Autoimmune associations!

The article, titled: Possible link between Hashimoto’s thyroiditis and oral lichen planus: a novel association found, was published in May of this year in the journal Clinical Oral Investigations.

Why I like this article:
In addition to narcolepsy, I also struggle with Hashimoto’s thyroiditis and lichen planus. (My lichen planus is predominantly on my ankles, however, and not in my mouth as it is for many people, including those covered in this article). The lichen planus appeared before I was formally diagnosed with Hashimoto’s, however, it is difficult to know when I developed Hashimoto’s, and it isn’t unreasonable to assume that I may have had the Hashimoto’s for quite some time prior to developing lichen planus.
What they found: 
The authors found that more people with oral lichen planus (OLP) had a higher incidence of Hashimoto’s thyroiditis (HT) than those that did not. In fact, 14.3% of people with LP had Hashimoto’s (13% more than the general population, which has a 1% occurrence of HT). They also found that in 93.3% of the cases where Hashimoto’s and LP presented together, the Hashimoto’s thyroiditis came first, suggesting a causal role for circulating anti-thyroid antibody in lichen planus.
Though novel, the finding isn’t altogether surprising.  In fact, lichen planus is associated with many other autoimmune diseases, including Sjrogen’s syndrome and lupus, and is considered a common skin rash among autoimmune patients.
What is interesting about the association between Hashimoto’s and skin disorders such as lichen planus, however, is that keratinocytes (skin cells) have been shown to express receptors for thyroid hormones, thus potentially serving as an extra-thyroid site of organ specific autoimmune attack.  This is speculative, as of yet, but it will be interesting to see if these antigens are upregulated in lichen planus lesions of individuals with Hashimoto’s thyroiditis.

Hashimoto’s disease, lichen planus, and lupus

While many autoimmune diseases are known to be associated with one another (take celiac disease and type I diabetes, for example), few reports exist in the literature documenting what is termed “Multiple Autoimmune Syndrome,” whereby an individual patient manifests three or more autoimmune diseases at the same time.  In fact, it is commonly asserted, though not conclusively shown (in my humble opinion), that multiple autoimmune syndrome is rare. 

I do not believe that this is accurate. In my limited experience, it seems to me that multiple autoimmunity is actually quite common, particularly in individuals with documented food sensitivities, such as celiac disease/gluten intolerance. When gluten, and other food, sensitivities exist, the gut becomes leaky and allows foodstuffs, bacteria, and other pathogens to pass the intestinal barrier, where they can be detected by the immune system.  While everyone likely harbors “self-reactive” immune cells, not everyone mounts an autoreactive immune response, like people with autoimmune disease do.  Pathogen (food, bacteria, or otherwise) encounter by the immune system in the gut delivers inflammatory signals, that may then lead to the activation and response of autoreactive immune cells.  In fact, current data suggests that all autoimmune diseases may begin in the gut.

Because of the supposed rarity of multiple autoimmune syndrome, my favorite articles are case studies of individuals with multiple autoimmunity. In the case reported here, a 24-year-old female presents with lichen planus (a suspected autoimmune disease), lupus (a known autoimmune disease), and hashimoto’s thyroiditis (also called autoimmune hypothyroidism), and to date, it is the first association of it’s kind.