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Secret biological recipes for a long life

Staying healthy as you get older – that is probably what many people would wish for. As part of the European research network “LifeSpan”, 130 scientists are now looking into how to make this wish come true. Prof. Dr. Graham Pawelec from the University Hospital of Tübingen (UKT) is one of the 130 scientists and his principal focus is immunological ageing processes.

It is not that long ago when the average human lifespan was just 40 to 45 years. Today– at least in western industrialised countries – it is about twice that. This increase is mainly due to dramatic improvements in medical treatment and care. However, even today, not everyone reaches retirement age. There are many different reasons for this, ranging from environmental factors to individual genetic differences.

LifeSpan, a research network with 12 million euros of EU funding, aims to identify the biological processes associated with ageing and to define suitable therapeutic measures. Professor Dr. Graham Pawelec from the Centre of Medical Research at the University Hospital in Tübingen is part of the project and hopes to focus in particular on the role of the immune system in the ageing process.

Prof. Dr. Graham Pawelec investigates the role of the immune system in the ageing process. (Photo: Pawelec / UKT)
“During evolution, a strong immune system has been a considerable selective advantage,” Pawelec states, explaining that infectious diseases have always been one of the major threats to human beings – this is still the case today, despite the availability of antibiotics. However, the immune system not only defends the human body against microorganisms, it also appears to play an important role in the elimination of tumour cells. There is evidence that immunocompromised people have a considerably higher risk of certain cancers. “There is apparently a connection between the decreasing efficiency of the human immune system as we age and the increased occurrence of infections and tumours,” said Pawelec.

But why is the immune system subject to an ageing process? Are there factors that might potentially influence this process? The LifeSpan network, which brings together 130 scientists from 10 countries, hopes to find answers to these questions within the next five years.

Exhausted immune system ages more rapidly

It is known from previous investigations that the number of T-cells does not only decrease with age, but that their function also deteriorates. T-cells are essential immune system cells which originate in the bone marrow and mature in the thymus. The thymus atrophies during puberty. The immunologically effective tissue is gradually replaced by fat so that, as time goes on, fewer and fewer T-cells mature in the ageing thymus. There is evidence that this loss of capacity is also responsible for the loss of T-cell function, but final proof is still missing.
However, it is known that cytomegalovirus (CMV) infections contribute considerably to the ageing of the immune system. CMV is a member of the herpes virus family. After having suffered an infection, the virus remains latent in the body for the rest of a person’s life. This results in a permanent antigen load and to the continuous stimulation of the immune system, and in consequence to the gradual exhaustion of the body’s own T-cell stores. This in turn prevents the organism from effectively fending off new pathogens. “There is also the hypothesis that all chronic infections – not only those caused by CMV – speed up immunosenescence,” said Pawelec. This also means that the immune system of those people who only come into contact with a limited number of antigens, or who have a genetic disposition that is better at fighting off infections, can remain effective until old age.

Hygiene conditions correlate with lifespan

It is also feasible that longer lifespan correlates with improved conditions of hygiene: the fewer pathogens that attack the human immune system during a person’s life, the less danger there is of exhausting the body’s T-cell stores. Pawelec regards this as a potential starting point for a new therapeutic strategy. “Perhaps it is possible to prevent premature ageing of the immune system by treating CMV infections very early or by preventing such infections through vaccinations.”

But there are several more promising ideas. One of these ideas centres around delaying, or at least partially reversing, the atrophic processes in the thymus. “This might considerably increase the efficiency of the immune system in elderly people,” said Pawelec. But it will be a long time before this method is available for human treatment. People hoping to boost their immune system might want to make small changes to their lifestyle. It has been shown in animals that calorie-reduced diets and physical activity improve the function of T-cells.

sb – 25 November 2008
© BIOPRO Baden-Württemberg GmbH

Further information:
University Hospital of Tübingen
Centre of Medical Research
Transplantation Immunology/Immunohaematology
Prof. Dr. Graham Pawelec
Waldhörnle Straße 22
72072 Tübingen
Tel.: +49 (0)7071-29 82805
Fax.: +49 (0)7071-29 4677
E-mail: graham.pawelec@uni-tuebingen.de

Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/secret-biological-recipes-for-a-long-life