Osteoglycin Across the Adult Lifespan

Context: Osteoglycin (OGN) is a proteoglycan released from bone and muscle which has been associated with markers of metabolic health. However, it is not clear whether the levels of circulating OGN change throughout the adult lifespan or if they are associated with clinical metabolic markers or fitness. Objective: We aimed to identify the levels of circulating OGN across the lifespan and to further explore the relationship between OGN and aerobic capacity as well as OGN's association with glucose and HOMA-IR. Methods: 107 individuals (46 males and 61 females) aged 21-87 years were included in the study. Serum OGN levels, aerobic capacity (VO2peak), glucose, and homeostatic model assessment for insulin resistance (HOMA-IR) were assessed. T-tests were used to compare participant characteristics between sexes. Regression analyses were performed to assess the relationship between OGN and age, and OGN and fitness and metabolic markers. Results: OGN displayed a nonlinear, weak "U-shaped"relationship with age across both sexes. Men had higher levels of OGN than women across the lifespan (β = 0.23, P =. 03). Age and sex explained 16% of the variance in OGN (adjusted R2 = 0.16; P <. 001). Higher OGN was associated with higher VO2peak (β = 0.02, P =. 001); however, those aged <50 showed a stronger positive relationship than those aged >50. A higher OGN level was associated with a higher circulating glucose level (β = 0.17, P <. 01). No association was observed between OGN and HOMA-IR. Conclusion: OGN was characterized by a U-shaped curve across the lifespan which was similar between sexes. Those with a higher aerobic capacity or higher glucose concentration had higher OGN levels. Our data suggest an association between OGN and aerobic fitness and glucose regulation. Future studies should focus on exploring the potential of OGN as a biomarker for chronic disease.