title: Serum levels of cathepsin K decrease with age in both women and men.
abstract: Bone turnover increases with age. In a previous study, we reported on bone metabolism in young and elderly women and men. The aim of the present investigation was to evaluate potential age- and gender-related changes in cathepsin K, a cysteine protease that plays an important role in the degradation of the organic matrix of bone. Twenty-five healthy premenopausal women, 24 young healthy men, 26 elderly women, and 25 elderly men participated in the study. Elderly women and men had significantly lower cathepsin K levels than younger ones. In both men and women, serum levels of cathepsin K were negatively correlated with age. In men there was a statistically significant negative correlation between serum levels of cathepsin K and osteoprotegerin, which inhibits osteoclast differentiation and activation. No association was found between serum levels of cathepsin K and bone-specific alkaline phosphatase, osteocalcin, or 25-hydroxy vitamin D. Thus, the age-related increase in OPG, which markedly inhibits the expression of cathepsin K, may also reduce serum levels of cathepsin K. Despite the age-related increase in bone resorption, this study shows lower cathepsin K values in elderly women and men than in younger subjects. It might be speculated that a different enzyme could compensate for the decline in cathepsin K during old age.
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria. katharina.kerschan-schindl@meduniwien.ac.at
authors.forename: K
authors.initials: K
authors.lastname: Kerschan-Schindl
authors.forename: G
authors.initials: G
authors.lastname: Hawa
authors.forename: S
authors.initials: S
authors.lastname: Kudlacek
authors.forename: W
authors.initials: W
authors.lastname: Woloszczuk
authors.forename: P
authors.initials: P
authors.lastname: Pietschmann
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D000469:Alkaline Phosphatase / Q000097:blood; D001862:Bone Resorption / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism; D056657:Cathepsin K; D002403:Cathepsins / Q000097:blood*; D003546:Cysteine Endopeptidases / Q000097:blood; D005260:Female; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D008297:Male; D015675:Osteocalcin / Q000097:blood; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear / Q000097:blood; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D006023:Glycoproteins; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506030:TNFRSF11B protein, human; D015675:Osteocalcin; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C534130:CTSK protein, human; D056657:Cathepsin K