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Baltimore Highlands, MD, United States

Ramanathan R.,Biology of Healthy Aging Program | Ramanathan R.,Yeshiva University | Kohli A.,Biology of Healthy Aging Program | Kohli A.,University of Maryland, Baltimore | And 7 more authors.
Journals of Gerontology - Series A Biological Sciences and Medical Sciences | Year: 2013

Background.Chitotriosidase (ChT) is secreted by chronically activated macrophages in Gaucher's disease. We hypothesize that circulating levels of ChT are altered with normal aging, reflecting age-related chronic macrophage activation. Potential sources that might contribute to altered levels were assessed by measuring systemic levels of ChT are -naphthyl acetate esterase, a macrophage lysosomal enzyme; granulocyte-macrophage colony-stimulating factor (GM-CSF), which stimulates neutrophilic granule release of ChT; interleukin-6 (IL-6); and neopterin, a macrophage activation marker.Methods.Serum was obtained from 315 healthy participants whose age ranged from 18 to 92 years. Anthropometric measures included percent body fat and body mass index. ChT and -naphthyl acetate esterase levels were measured by enzyme activity assays. GM-CSF, IL-6, and neopterin concentrations were measured by commercial enzyme-linked immunosorbent assays. Serum marker values were statistically analyzed using nonparametric tests.Results.Six percent of the participants had undetectable ChT levels. A positive association with age was observed for ChT and IL-6, whereas a negative correlation with age was seen for -naphthyl acetate esterase and GM-CSF. ChT values were not associated with -naphthyl acetate esterase or GM-CSF levels. ChT was independently associated with IL-6 and neopterin levels, but statistical significance was attenuated when controlled for age.Conclusions.The data are consistent with increased serum ChT activity not arising from altered macrophage lysosomal enzyme trafficking or GM-CSF-stimulated release of neutrophil granule stores. The association of ChT with age remains significant after controlling for neopterin and IL-6 changes with age, suggesting that ChT levels reflect a macrophage state distinct from acute macrophage activation or inflammatory state. © 2013 © The Author 2013. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. Source

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