Take growth hormone: the thymus will be like a young one!
Scientists at the Gladstone Institute of Virology and Immunology at the University of California, working under the guidance of Dr. Laura Napolitano, have developed a therapeutic approach that provides stimulation of the production of viable T-lymphocytes in adult HIV-infected patients.
HIV destroys T-lymphocytes, which leads to insufficiency of the immune system and the development of severe infectious diseases. The thymus, or thymus gland, in which T-lymphocytes mature, functions most intensively in humans during puberty, and gradually evolves as they grow older. In adults, the thymus practically does not function, which makes it difficult to restore the normal number of T-lymphocytes in the body of HIV-infected people. Thus, theoretically, stimulation of the thymus can help such patients in restoring the devastated immune system.
Despite the fact that for a long time experts adhered to the hypothesis that the human thymus cannot be reactivated, the authors demonstrated that growth hormone is able to stimulate the ability of this gland to produce T-lymphocytes.
According to the authors, activation of T-lymphocyte production can be used not only in the treatment of HIV infection and other immunodeficiency, but also, for example, to accelerate the restoration of the immune system during bone marrow transplantation.
The results of earlier studies, indicating that growth hormone increases the functional activity of the thymus of aging mice, prompted scientists to conduct a randomized study involving HIV-infected patients.
As part of the work, the authors observed 22 HIV-infected patients for 2 years. The randomly selected half of the participants continued to receive treatment according to the usual protocols, which were supplemented with growth hormone during the first year. The second half of the participants – the control group – started receiving growth hormone only in the second year of follow-up, while the experimental group was canceled. The state of the immune system of all participants was regularly analyzed. The size and shape of the thymus were assessed using computed tomography, and the number of immune cells in the blood and the ratio of cells of different types were assessed using multiparametric flow cytometry.
Prior to the start of the study, all participants received effective antiviral therapy for at least one year (3 years on average) with pronounced suppression of virus activity. Despite the effectiveness of therapy, they maintained abnormally low levels of CD4+ T-lymphocytes, which are necessary for the formation of full-fledged immunity. At the beginning of the study, patients of both groups had no significant differences in such indicators as age, average duration of effective therapy, viral load, thymus size and various immunological parameters.
The authors found that growth hormone significantly increased the size of the thymus and the number of newly formed CD4+ T lymphocytes. On average, taking growth hormone increased the number of CD4+ T-lymphocytes by 30%, which was 2.4 times higher than the same indicator for patients in the control group. The effects of growth hormone continued to intensify for at least three months after the drug was discontinued and persisted for at least a year.
The results are very encouraging, but the authors warn that additional studies are needed to clarify the usefulness of T-lymphocytes formed under the influence of growth hormone. In addition, additional study requires the possibility of developing side effects of long-term intake of growth hormone acting on many types of body cells.
It should also be noted that a relatively small number of patients participated in the trials, which makes it difficult to draw unambiguous conclusions. However, when conducting a larger multicenter trial, the AIDS Clinical Trial Group received similar preliminary results. Detailed processing of the data obtained will provide more complete information about the effect of growth hormone on the immune system.
Article "Growth hormone resurrects adult human thymus during HIV-1 infection" published in the March issue of the Journal of Clinical Investigation.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
27.02.2008