Articles about ‘inflammation’ seem to be everywhere these days, and inflammation seems to be blamed for everything from heart disease to mood disorders to obesity. But how does this somewhat nebulous idea of too much inflammation tie into our genes? It seems that some people have a more sensitive immune system and are more prone to inflammatory reactions. In looking into the effects of emulsifiers on our gut, I came across quite a few genetic variants that are involved in increased inflammation and increased risk of inflammatory bowel diseases.
Interleukin-17 (IL-17A gene) is a pro-inflammatory part of our immune system that, while necessary in times of injury or pathogenic infection, can cause problems if it is overactive.[ref] It is implicated in increasing the risk for several autoimmune diseases including psoriasis and asthma. Genetic variants that increase the body’s production of IL-17A have been shown to be a risk factor for IBD, rheumatoid arthritis, bronchitis severity, gastric cancer, and more. IL-17A is also implicated in celiac disease, with increased expression of IL-17A found in the intestinal mucosa of Celiac patients. Gluten sensitivity, though, was not found to increase IL-17A.[ref] [ref]
IL-17A Genetic Variants:
There are genetic variations of IL-17A that can cause it to be either more active than normal (increasing risk of autoimmune/inflammatory conditions) or less active than normal (protective against autoimmune/inflammatory conditions). As is the case with most genetic variants, diet and environment interact with genetics in the development of chronic diseases.
Variants that cause IL-17A to be more active:
Studies show that the rs2275913 variant (AA and AG genotypes) increases the risk of autoimmune diseases, periodontal disease, gastric cancer, and inflammatory bowel diseases [ref] [ref] [ref] [ref] [ref] There are quite a few studies on this variant in different populations showing the increase in IL-17A and an increased risk of inflammatory conditions. In the “pro” column for this variant is the fact that overactivity may be protective against infective diseases like tuberculosis.[ref]
Check your 23andMe results for rs2275913: (v.4 and v.5 )
- AA: increased risk of inflammatory conditions: autoimmune, periodontal, inflammatory bowel
- AG: somewhat increased risk of inflammatory conditions.
- GG: normal
Variants that cause IL-17A to be less active:
Check your 23andMe results for rs8193037: (v. 4 only)
Check your 23andMe results for rs3819025: (v.4 only)
- AA: possibly protective against inflammatory conditions inc. autoimmune thyroid [ref]
- AG: possibly protective against inflammatory conditions
- GG: normal
Vitamin D (in vitro study) may decrease high IL-17 levels. Get out in the sunshine, or look into supplementing with vitamin D (do a blood test first to determine your vitamin D status). Be sure to read the labels on the vitamin D supplement and go for a vitamin D3 without soybean or cottonseed oil.
More to Read:
IL-17A variants don’t act alone in increasing susceptibility to inflammatory conditions; environmental elements play a role as well.
- Th17 Cytokines and the Gut Mucosal Barrier
- The Influence of Polymorphisms of Interleukin-17A and Interleukin-17F Genes on the Susceptibility to Ulcerative Colitis
Originally published 1/16/17, updated 10/11/18.