2015-10-21 13:18:40
Eating disorders are a serious health problem that affects around 5% of women and 2% of men. These disorders are characterized by an unhealthy relationship with food. Among them are bulimia nervosa, a kind of irrepressible urge to eat a lot, later compensated by vomiting; hyperphagia, a similar drive to eat a lot, but without compensatory mechanisms, which quickly leads to obesity; and anorexia nervosa, the dangerous propensity to deprive oneself of food that leads to malnutrition and extreme thinness.
The problem of anorexia is of such magnitude that countries like France have enacted laws prohibiting fashion brand models from being too thin. The reason is, in part, that anorexia is believed to be caused by psychosocial factors, that is, pressures from the social environment to achieve certain standards of beauty, which can induce them in the most susceptible part of the population, such as mainly women. teenagers.
However, scientists dedicated to the investigation of biological processes know that these, even if they are psychosocial in nature, must ultimately involve some genetic, hormonal, or molecular imbalance, in short, since not even the mind is capable of functioning in this way. adequately without a correct balance of numerous molecules, including hormones and neurotransmitters. Scientists know that social factors, stress, or mental disorders have to be mediated by some molecular mechanism that goes into imbalance, a mechanism that must be unraveled to completely clarify the cause of eating disorders. They also know that the clarification of its ultimate molecular cause may offer the possibility of more effective preventive and curative treatments than the prohibition of models being excessively thin.
It is also well known that appetite control involves numerous hormonal mechanisms, which affect eating behavior, that is, whether we decide to start eating, continue eating, or stop. Hunger and feelings of satiety are controlled by a series of hormones and mechanisms that affect the nerve cells that control whether we eat or not. For this reason, it is very likely that both bulimia and anorexia can be caused by some hormonal imbalance, which may also be caused or aggravated by some other susceptibility of genetic origin.
Culprit bacteria
Considering these ideas, researchers at the University of Rouen (France) are exploring a relatively new scientific hypothesis that postulates that eating disorders could be caused by problems with the immune system, in particular by the development of autoimmunity. Autoimmunity consists of the immune system mistakenly attacking our own body. There are important autoimmune diseases, some of which affect the functioning of the hormonal system of the thyroid gland. Therefore, it is possible that an autoimmune problem could also affect the appetite hormone system.
Very good, but for an autoimmune problem to trigger, some initiating factor is necessary. These factors may include certain genetic susceptibilities, but also infections. For example, infection by a bacteria that has a protein similar to one of ours can induce antibodies to be generated against the bacteria’s protein that will also attack ours, causing autoimmunity. Fortunately, this does not always happen, and some infected people (very few) develop autoimmunity, but most do not. It is believed that certain genetic factors would explain these discrepancies.
Researchers find that autoimmunity is involved in anorexia and bulimia, but not due to an infection, but rather due to our own intestinal flora bacteria, in particular the well-known E. coli bacteria. Scientists discover that this flora bacteria produces a protein called ClpB that has a region of amino acids very similar to that of the hormone called alpha-MSH, which causes a feeling of satiety and makes us stop eating by acting on the hypothalamus. cerebral.
The researchers explain that the similarity between ClpB and alpha-MSH causes that sometimes (stress, intestinal damage, etc.) the ClpB protein passes from the intestine to the blood and antibodies are generated against it. These antibodies can also bind to the hormone alpha-MSH and affect the way it works to control appetite, which researchers say could affect the development of both anorexia and bulimia.
Scientists confirm these data in several ways. One is the finding of antibodies against the hormone alpha-MSH in the blood of people with anorexia or bulimia. Another is that the injection of the ClpB protein into mice induces the generation of antibodies against it and a significant modification of their eating behavior, and this despite the fact that the mice are not fond of fashion.
These findings are now redirecting attention toward controlling immunity and hormonal functioning to prevent and treat anorexia and bulimia and perhaps even other eating behavior problems. Let’s hope that, together with greater social awareness of these problems, they will finally be solved.
Referencia: N Tennoune, et al (2014). Bacterial ClpB heat-shock protein, an antigen-mimetic of the anorexigenic peptide α-MSH, at the origin of eating disorders. Transl Psychiatry (2014) 4, e458; doi:10.1038/tp.2014.98
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