Reduced serum corin levels in patients with osteoporosis.

BACKGROUND

Corin is a cardiac protease that activates the natriuretic peptides. Corin is also expressed in chondrocytes and bone marrow-derived mesenchymal stem cells that undergo osteogenic differentiation, suggesting a potential role of corin in bone formation and homeostasis.

METHODS

To test if corin levels are altered in patients with bone disease, we used ELISA to measure corin and osteocalcin levels in serum samples from healthy controls (n = 134) and patients with osteopenia (n = 53) and osteoporosis (n = 101).

RESULTS

In patients with osteopenia and osteoporosis, serum corin levels were 510 ± 228 and 478 ± 183 pg/ml, respectively, which were significantly lower than that in healthy controls (682 ± 240 pg/ml) (both p values<0.001). The reduced serum corin levels were found in both male and female patients. In multiple linear regression analysis, bone mineral density was identified as an independent predictor for serum corin levels. In patients with osteopenia and osteoporosis, but not normal controls, a negative correlation was found between serum corin and osteocalcin levels.

CONCLUSIONS

Serum corin levels were reduced in patients with osteoporosis and the reduction was associated with high rates of bone turnover. Low serum corin levels may reflect impaired bone homeostasis in patients with osteoporosis.