13 July 2009

Immunity and longevity

Scientists have bred long-lived miceAlexey Tymoshenko, GZT.ru

Biologists have managed to increase the lifespan of mice by a third. Scientists have achieved this effect by preserving the thymus in animals – an organ of the immune system, which usually loses its functions with age.

Researchers from the University of Pittsburgh (USA) used genetically modified rodents. The experimental mice were deprived of the PAPPA gene, which, among other things, is responsible in the body for the action of various hormones, including in the thymus.

Thymus forever

Science knows that the thymus is an important organ of the immune system. It usually begins to decrease in size after puberty, and the increased susceptibility to diseases in a person in old age is partly due to the fact that the thymus loses its functions over the years. But in mice deprived of the PAPPA gene, the thymus practically does not change in size until old age!

In their article published by the journal Proceedings of the National Academy of Sciences, scientists noted that the immunity of animals deprived of PAPPA practically does not decrease with age. In addition, after a year and a half of life in a new species of mice (and a mouse lives no more than three years), even more lymphocytes were produced compared to ordinary rodents. The only external difference between the new individuals was their small size, otherwise they did not differ from ordinary mice.

Hormones and development

By itself, the PAPPA gene is associated not only with the thymus and immunity. The protein encoded by it increases the susceptibility of cells to one of the hormones – the insulin-like growth hormone IGF. Similar to insulin, this hormone is important for the development of the body during various periods of its existence, and the greatest activity of the PAPPA protein regulating its activity is noted in the tissues of the placenta, that is, during intrauterine development.

In the adult body, PAPPA is inactive, but scientists have a suspicion that it is associated with an excessive level of IGF, which no longer promotes growth, but, on the contrary, degradation of the thymus. This suspicion, based on the already known role of IGF (and, consequently, PAPPA) in the development of the thymus, has been confirmed by studies.

As the scientists report in their article, it is now necessary to study the consequences of removing the PAPPA gene on the development of cancerous tumors and on a number of mechanisms of the body's fight against infections that have so far been ignored. There is no question of transferring the results to clinics yet. But the value of the discovery is already great enough: it has allowed scientists to advance in understanding the links between immunity and longevity.

Any protein is encoded by a gene. And this allows us to talk about both the PAPPA protein, if we are talking about a protein molecule, and the PAPPA gene – if the genetic code is being discussed. The phrase "gene x activates gene y" sounds like this in a different way: first, protein X is synthesized, encoded by gene x, and then this protein starts the process of synthesis of Y-protein encoded by gene y.

Immunity and longevity

It should be noted that life extension is not always associated with increased immunity. In another work (see the article Will an immunosuppressant help you live up to a hundred years?) scientists noticeably prolonged the life of rodents due to a protein that, on the contrary, suppressed the immune system. Such a paradoxical, at first glance, conclusion is explained by the fact that many proteins act in several ways.

An overly active immune system can "attack" its own cells, mistaking them for someone else's. For this reason, you should not get carried away with immune-boosting drugs on your own: arthritis and diabetes are listed among autoimmune diseases.

The same protein in different situations and in different cells sometimes has the opposite effect. There are proteins associated simultaneously with the development of tumors, cell division, memory formation and liver function: such a variety of functions is provided by a subtle mechanism of interaction of dozens of proteins.

What else besides regulating the life of the thymus can PAPPA do is the subject of further research. And in relation to the recently discovered rapamycin, additional research is expected to continue.

Portal "Eternal youth" http://vechnayamolodost.ru13.07.2009

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