Biotechnology for celiac disease

Posted On
Posted By Irma J. McKeehan

When a foreign element enters our body, such as a bacterium or a virus, our immune system starts up and makes an army ready to fight it. These are the antibodies or immunoglobulins, soldiers totally specialized in the search and capture of those antigens that damage our body. These antibodies travel through the blood and know exactly what they must attack, as they were designed to look for an unmistakable signal.

The system seems infallible, it has a versatility that allows to generate as many concrete antibodies as antigens exist, but it has a weak point and it is that as in almost all the so complex systems, there are possibilities of error.

The most serious flaw that can happen in our immune system is that we make antibodies that attack the wrong substances. These are the well-known autoimmune diseases, when the antibodies no longer play in our favour, but mistakenly attack healthy cells in our own body.

We say that they are the most serious, because most autoimmune diseases are chronic, they have a treatment for the control and reduction of symptoms, but they cannot be cured. A good example of an autoimmune disease is celiac disease.

In this case, there is no drug that can prevent the inflammatory response that gluten causes in the intestine of coeliacs, the only treatment is a diet free of this protein for life. But biotechnology has developed techniques that make it easier for coeliacs to stick to their diet, using molecules similar to those involved in the problem: antibodies.

An autoimmune disease that attacks the digestive system

The problem of coeliacs begins when they consume cereals such as wheat, barley or rye and some varieties of oats, which release harmful compounds: GIP (Gluten Immunogenic Peptides).

These GIP or Gluten Immunogenic Peptides are the fraction of gluten that is toxic to coeliacs, those peptide fragments that resist gastrointestinal digestion and are excreted in faeces and urine. They can be detected in these samples if sufficiently sensitive and specific immunological techniques are used.

Once in the intestinal mucosa, the gluten fragments bind to the enzyme tissue transglutaminase (tTG) and together, form a complex that is mistakenly perceived as a dangerous substance by the immune system of coeliacs.

The B-lymphocytes then send specific signals to the T-lymphocytes to start the manufacture of IgA and IgG antibodies, which act against the transglutaminase by triggering the autoimmune response that attacks the enzyme normally present in our intestine.

At the end of this whole chain, the consequence is that the autoimmune reaction causes atrophy of the intestinal villi. These villi are extensions of the intestinal mucosa and play an important role in nutrition.

When they are affected, the surface area for absorbing nutrients decreases, and so undiagnosed coeliacs, or those who do not follow the gluten-free diet, suffer serious nutritional problems until they completely eliminate gluten from their diet.

How biotechnology helps control coeliac disease

Since the only treatment for autoimmune celiac disease is to follow a strict lifelong gluten-free diet, one of the best ways medicine can help these patients is in effectively controlling adherence to this diet. And now, a new form of control is possible thanks to the development of antibodies A1 and G12, capable of detecting GIP in the faeces and urine of coeliac patients who ingest gluten.

Because they are resistant to digestion, part of the GIP is excreted in the stool without being absorbed and the other part crosses the barriers of the intestine, generating the coeliac’s immune response and eventually being excreted in the urine. The detection of IGP with the antibody G12 and/or A1 in the stool and urine samples, then becomes irrefutable evidence that the coeliac patient has ingested gluten voluntarily or involuntarily and must correct their usual diet.

Not consuming any gluten is very difficult and clinical results have already been obtained which indicate that almost half of coeliacs fail to comply with the diet at least once a week. Despite the fact that coeliacs make an effort to follow the gluten-free diet, not knowing when a food may have been contaminated voluntarily or involuntarily is very frustrating.

In addition, the symptoms associated with gluten intake can sometimes be similar to a viral or bacterial infection or other food poisoning.

Prior to this method of detecting GIP with the G12 antibody, the only way for the doctor to monitor the patient’s adherence to the diet was through questionnaires or serologies, which are not very accurate due to the fact that they are not always accurate.

Again, biotechnology presents solutions to chronic diseases that need to be monitored such as glucose strips for diabetes. Now coeliacs can verify the correct diet follow-up and avoid the cumulative health problems derived from dietary transgressions, since small involuntary intakes of gluten have serious long-term consequences for the coeliac, often without causing symptoms.