Healthy aging is associated with unaltered production of immunoreactive growth hormone but impaired neuroimmunomodulation.
BACKGROUND
Both endocrine and immune systems are continuously remodeled during aging.


OBJECTIVE
Here, we investigated to what extent adrenal and somatosenescence are associated reciprocal changes in the immune system during strictly healthy aging.


METHODS
Forty-six elderly subjects and 33 young adults were recruited according to the health criteria of the SENIEUR protocol. Peripheral blood mononuclear cells were isolated and stimulated in vitro with lipopolysaccharide or phytohemagglutinin to assess the production of immunoreactive growth hormone (GH). Peripheral sensitivity to steroids was assessed in vitro by dexamethasone-, cortisol- or dehydroepiandrosterone (DHEA)-induced inhibition of T-cell proliferation. DHEA and GH levels were measured by radioimmunoassays.


RESULTS
Healthy elderly had lower salivary DHEA and serum GH levels (somatosenescence). They presented reduced T-cell sensitivity to dexamethasone but similar cellular sensitivities to cortisol and DHEA. Their cells produced similar levels of immunoreactive GH compared to the cells of young adults.


CONCLUSIONS
These data indicate that healthy aging is associated with adrenal and somatosenescence as well as impaired neuroendocrine immunoregulation at the level of the lymphocyte. In addition, somatosenescence may not be associated with a reciprocal decline in immunoreactive GH.
Luz
Clarice
C
Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.
Collaziol
Diego
D
Preissler
Thales
T
da Cruz
Ivana M
IM
Glock
Luiz
L
Bauer
Moisés E
ME
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology* / Q000378:metabolism; D019540:Area Under Curve; D049109:Cell Proliferation; D002478:Cells, Cultured; D003687:Dehydroepiandrosterone / Q000032:analysis / Q000378:metabolism; D005260:Female; D005938:Glucocorticoids / Q000378:metabolism; D019382:Human Growth Hormone / Q000096:biosynthesis* / Q000097:blood; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D015213:Neuroimmunomodulation / Q000502:physiology*; D012463:Saliva / Q000737:chemistry; D013601:T-Lymphocytes / Q000378:metabolism
D005938:Glucocorticoids; D019382:Human Growth Hormone; D003687:Dehydroepiandrosterone