Another disappointment: irisin will not help from diabetes and obesity
The results obtained by an international group of researchers from the USA, Germany, Norway and Switzerland questioned the effectiveness of the hormone irisin discovered three years ago (see the note "To the attention of the fat and lazy: do you want a shot instead of physical education?"), named after the ancient Greek goddess of the rainbow Iris, and the reliability of more than 170 dedicated to it publications. Until now, it was believed that irisin has an effect on the body similar to the effect of physical exertion, but the authors claim that this statement is based on the results, the fallacy of which is due to the use of imperfect analytical kits.
A study conducted in 2012 showed that in response to physical exertion, the terminal fragment of the muscle protein FNDC5, later called irisin, cleaves off and moves with the blood flow from muscles to adipose tissue, where it turns energy-storing white fat into brown fat, whose function is to quickly burn calories. This discovery gave rise to the hope that irisin can become a cherished means to combat diabetes and obesity and that in the future taking irisin tablets will allow you to get rid of excess weight without physical exertion.
Subsequently, many studies were conducted on the study of changes in the level of irisin during exercise, diabetes, obesity and even cancer. To measure the level of this hormone in the blood, most researchers used commercial enzyme immunoassay kits (ELISA) produced by several biotech companies.
However, a new study has demonstrated that the antibodies included in these kits do not have sufficient specificity. The authors claim that the results of assessing the level of irisin obtained using commercially available kits were due to unknown blood proteins, which led to a misinterpretation of the role of this hormone in metabolism.
The researchers came to such conclusions when conducting direct testing of antibodies used in earlier studies. The obtained results demonstrated their cross-reaction with proteins other than irisin, which provided false positive results. Moreover, all proteins identified by analytical kits in human and mouse blood samples differed from irisin even in size.
The authors believe that the data they obtained cast doubt on the reliability of all earlier results obtained using commercial irisin identification kits using enzyme immunoassay. They also suggest that this hormone has no physiological function in the human body at all. This assumption is consistent with the results obtained by another research group, which found that the human version of FNDC5 contains a serious mutation, as a result of which the human body synthesizes less than 1% of the amount of irisin produced in the body of other species. In fact, the FNDC5 gene is knocked out in the human genome, so a person cannot produce its protein product and, accordingly, irisin.
Article by Elke Albrecht et al. Irisin – a myth rather than an exercise-inducible myokine is published in the journal Scientific Reports.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Duke University:
Scientists Find “Exercise Hormone” Irisin Is More Myth Than Reality.
11.03.2015