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Scientists manage to rejuvenate the immune system of old mice

Scientists manage to rejuvenate the immune system of old mice

An antibody therapy, described this Wednesday in the journal Nature, has managed to rejuvenate the immune system in elderly mice and researchers believe that it will be viable in humans once it passes preclinical and clinical studies.

As people age, the immune system weakens and there are difficulties in fighting diseases and new viruses, and for vaccines to combat the latter to take effect, as happened with covid-19.

The cause is in hematopoietic cells or adult stem cells, responsible for producing lymphocytes, which defend the body against any new threat (adaptive immunity), and myeloid cells, which respond with inflation to pathogens (innate immunity).

The researcher at the Faculty of Medicine of the Universidad de Stanford, Irving Weissman, one of the authors of the present study isolated these adult stem cells in mice and humans in the late 1980s.

Their research has shown how in the last stage of life, the production of lymphocytes and myeloid cells by adult stem cells becomes unbalanced: the creation of lymphocytes falls, and with it the ability to react to new viruses and bacteria, and The number of myeloid cells increases, which kill any unknown cells through inflammatory responses.

This inflammation is a problem when it is triggered inappropriately or excessively, as occurs with aging, when people experience a type of chronic inflation due to the abundance of myeloid cell production to the detriment of lymphocytes.

At the beginning of human history, when people did not move from the place where they were born and lived with the same pathogens all their lives, producing fewer lymphocytes in old age was not a big problem. However, now that mobility favors the continuous appearance of unknown viruses and bacteria, it is.

The question the researchers asked themselves was whether it is possible to maintain a younger immune system, decreasing adult stem cells with a myeloid tendency and increasing the more balanced ones, which also produce lymphocytes.

Experiments with mice have confirmed that it is.

They treated rodents between 18 and 24 months of age (equivalent to more than 70 years in humans) with an antibody aimed at destroying adult stem cells with a myeloid tendency and replacing them with more balanced ones, with a greater presence of lymphocytes.

The treatment also reduced some negative consequences, such as inflammation that can arise when an aging immune system confronts a new pathogen.

When the treated geriatric mice were vaccinated two months later against a virus they had not encountered before, they saw their immune systems respond much better than those of the untreated animals.

Four months after the administration of the therapy, the mice with a rejuvenated immune system developed a better immune response against a virus against which they had previously been vaccinated.

Similar to humans

Researchers have also shown that adult mouse and human stem cells are similar enough that it may one day be possible to use a technique similar to the aging human immune system, making people less vulnerable to new infections and having better health. response to vaccination in advanced ages.

“We believe this study takes the first steps to apply this strategy in humans. If we can revitalize the aging human immune system as we did in mice, it could save lives when the next pandemic comes,” says another of the authors, Ross Myers, from the Laboratory Rocky Mountain from the US National Institutes of Health.

Óscar de la Calle-Martín, secretary of the Spanish Society of Immunology, recalls that the increase in the number of myeloid cells in elderly patients reduces survival in a large number of age-related diseases.

“Balancing the production of these cells can help in the treatment of diseases as prevalent as atherosclerosis, neurodegenerative diseases, osteoporosis or cancer,” he underlines in a reaction collected by the Science Media Center platform.

Medical researchers Yasar Arfat Kasu and Robert Signer of the University of California San Diego warn, however, that increased lymphocyte production in older adults could increase the risk of tumor growth (such as leukemia), which It has been shown to be suppressed by reducing lymphoid production.

“However, the burden of a greater risk of lymphoid leukemia could be offset by greater protection against infections and a lower risk of other cancers if there was greater immunological surveillance with therapies like this,” they add, Efe reports.