The impact of environmental triggers on autoimmune disease is, and has been for several years, an area of great interest among researchers and clinicians, clearly indicating that there is some sort of connection between the two, as evidenced in these studies about autoimmune thyroid disease and lupus.
Presently there are still a lot more questions than answers in this arena, but it is still encouraging to see the widespread interest and investigation into potential connections. It is often very difficult to tease apart the effects of individual factors, but fortunately those suffering from autoimmune disease will likely benefit from continuing research, and hopefully the therapeutic advances that follow.
The list of possible triggers is quite extensive, and certainly not all-inclusive, as studies worldwide continue to discover additional possible links and then look to validate these findings with further research.
Some of the many triggers that investigators believe have some causal connection to autoimmune disease include:
These triggers are suspected of exploiting genetic predispositions to autoimmune conditions, causing clinical disease as a result as shown in this Danish twin study.
One fascinating area that researchers are particularly excited about is called “citrullination” (I had never heard of it either), whereby normal bodily proteins are converted into autoantigens, which then provoke autoimmune attacks on various tissues and organs. The science is quite complex and beyond the scope of this article, but this process is thought to be an intermediate step between environmental triggers and actual clinical disease. Of course there are still many unanswered questions about this mechanism, but it is certainly a promising start that may provide a focus for future therapies.
On the other hand, the hygiene hypothesis, which we have covered before, is an example of one theory that proposes a contrasting process leading to disease. Proponents say that one of the possible factors affecting the high prevalence of autoimmune conditions in developed nations is the fact that we may have become too clean for our own good. That is, because our bodies were designed to encounter and deal with a certain level of microbial intrusion, our sterilized world today presents fewer opportunities for such interactions (especially from parasites, which may confer considerable protection from autoimmune disease in undeveloped areas).
Left without as much work to do, it is believed that our immune cells look for additional targets and end up attacking our own bodies. In a sense then, the hygiene hypothesis, while not directly dealing with environmental factors as causative agents of disease, is pointing to a lack of infective activity as being potentially responsible for the high rates of autoimmune diagnosis seen in certain areas today.
As many patients are aware, infections, especially from viruses, are thought to play some role in triggering many disorders, of the immune system and otherwise. While there is still much to be discovered regarding the mechanisms of disease, scientists have made some definite advances in this area. We’re not yet on the verge of a major breakthrough in most cases, but we do appear to be getting closer every day.
Most of the hypotheses involving viral and other infectious autoimmune factors are very complex and technical. However, one theory that has researchers very excited is the finding that stress (a broad term for an anxiety-inducing state) is clearly linked to a decrease in something called “viral latency”. This essentially means that increased levels of stress induce sleeping viruses within the body to awake and become active as infectious agents. As a result of reduced viral latency, the thinking is that there are simply more active viruses circulating in the bloodstream, so there are more chances of triggering disease processes.
Another possible connection that has been suspected to involve an infectious trigger is something called PANDAS, which stands for Pediatric Autoimmune Neuropsychiatric Disease Associated with Streptococcus infection. Some of you may be familiar with this acronym, especially if there are children with autoimmune disease involved in your life. The connection is vague, but there does seem to be a positive correlation between those who suffered from various Strep infections as children, and the later development of a range of possibly autoimmune illnesses, including autism and obsessive-compulsive disorder, among others. While this has provided an exciting avenue for research, the exact nature of the link is still largely unknown, though some progress has been made.
In an age when it is quite common to consume food laden with additives and preservatives, and in which fruits and vegetables are routinely doused with pesticides and livestock filled with antibiotics and hormones, it isn’t hard to imagine all of these unnatural products having deleterious effects on the population being served.
Indeed, scientists may not be very certain about their role in autoimmune illness yet, but most are fairly confident that something connects foodstuffs and autoimmune disease. Just as with the hygiene hypothesis above, the lower prevalence of autoimmune diagnosis in developing nations may very well also be linked to the lack of food processing in those countries, which rely on more rudimentary food sources.
The good news is that researchers seem to have some insights into this purported connection; the bad news is that just as with other possible autoimmune condition-inciting factors, it can be extremely difficult to parse exactly which substances are causing which problems, and how.
However, the silver lining, in an otherwise frustrating situation for many, is that studies have started to identify potential connections, which is the first step to clarifying mechanisms and introducing new therapies. Though they are still a mystery in many ways, parts of the autoimmune puzzle are beginning to fall into place.
Because research into the dietary connection is still relatively new, there aren’t all that many studies published regarding specific triggers. One exception though is that of researchers at Yale, who last year discovered a possible link between excessive salt intake and autoimmune conditions. It’s too early to say with certainty whether salt is a definite autoimmune trigger, or how it acts to induce autoimmune disease, but the fact that studies are looking into this connection, and that at least one may have been revealed, is very good news.
As more and more becomes known about the causes of autoimmune conditions, we can count on science uncovering other links, some of which will undoubtedly aid in the development of more effective treatment strategies, whether based on food intake, infections or triggers as yet unknown to those in the research community.
About the Author
Dr. Rothbard is a professional medical writer and consultant based in New York City, specializing in medical education articles targeted at a variety of audiences, from children through clinicians. After leaving medicine, he worked as a biology and medical science educator for several years, before deciding to pursue writing full-time. He may be reached at [email protected].
This blog post was originally published by AutoimmuneMom.com, written by Dr. Rothbard, and first published on Jul 8, 2014.