Bone marrow adipose tissue mass and dipeptidyl peptidase-4 link aging and metabolic health to biomarkers of bone turnover.

Age was the strongest determinant of increased bone marrow adipose tissue (BMAT) mass, explaining more than a third of its overall variation.

• The study used magnetic resonance imaging to assess proton density fat fraction to quantify BMAT mass in healthy individuals.
• Age explained more than a third of the overall variation in BMAT mass.
• Age was also described as a robust determinant of bone turnover.
• The cohort was cross-sectional and consisted of healthy women and men.

A sex-specific correlation pattern was observed between BMAT mass and bone turnover biomarkers.

• Women displayed a trend for a positive correlation between BMAT and bone turnover biomarkers, which depended on age.
• In men, BMAT mass correlated significantly but inversely with both bone turnover biomarkers (P1NP and β-CrossLaps).
• The inverse correlation in men was also age-dependent.
• Bone turnover biomarkers assessed were procollagen type 1 N-terminal propeptide (P1NP) and β-CrossLaps.

DPP4 concentration and activity were positively associated with P1NP in both sexes, independently of age, BMI, or HbA1c.

• Dipeptidyl peptidase-4 (DPP4) concentration and activity were measured as biomarkers of metabolic health.
• The positive association between DPP4 and P1NP was observed in both women and men.
• These relationships were independent of age, BMI, or HbA1c.
• This suggests DPP4 links bone turnover to metabolic health independently of general metabolic or aging factors.

High levels of bone marrow adipocyte accumulation are observed during aging and in individuals with diabetes and obesity.

• BMAT has been linked to negative bone health outcomes.
• The study correlated BMAT results to sex, age, body mass index (BMI), and glycated hemoglobin A1c (HbA1c), which represents long-term glycemic control.
• This background context motivated the exploration of relationships between BMAT, age, metabolic health, and bone turnover.

The impact of BMAT on bone turnover may be age-dependent, whereas metabolic regulator DPP4 is linked to bone turnover independently of metabolic health or aging.

• BMAT-bone turnover associations differed by both sex and age group.
• DPP4 associations with P1NP persisted after controlling for age, BMI, and HbA1c.
• Increased marrow adipocytes were proposed to produce endocrine signals, such as DPP4, which modulate these associations.
• Women and men had distinct associations between bone turnover, age, and bone marrow adipocytes.