The Neuropeptide Vasoactive Intestinal Peptide Levels in Serum are Inversely Related to Disease Severity of Postmenopausal Osteoporosis: A Cross-Sectional Study.

ABSTRACT

Background: The neuropeptide vasoactive intestinal peptide (VIP) has been identified as inhibiting osteoclastogenesis and suppressing inflammation. Objective: This study was conducted to examine serum VIP levels in postmenopausal osteoporosis (PMOP) patients and explore the correlation of serum VIP levels with disease severity of PMOP. Methods: A total of 106 postmenopausal women diagnosed as osteoporotic were enrolled in the study and 102 postmenopausal women with normal bone mineral density (BMD) were enrolled as controls. BMD at the femoral neck (FN), lumbar spine 1-4, and total hip were examined using dual-energy X-ray absorptiometry. Genant semiquantitative grading was used for vertebral morphometry and fracture. Serum VIP levels were tested using enzyme-linked immunosorbent assay. Serum inflammatory factor interleukin-1ß (IL-1ß), osteoclastic activity marker tartrate-resistant acid phosphatase 5b (TRACP-5b), and estrogen-2 (E2) were also examined. Receiver operating characteristic (ROC) analyses was performed to determine the diagnostic values of serum VIP, IL-1ß, TRCAP-5, and E2 with regard to Genant grade. Results: Our findings demonstrated a reduction in the serum level of VIP expressed in PMOP patients compared with controls. In the PMOP group, patients with lumbar fracture had significantly lower serum VIP concentrations in comparison with healthy controls. Serum VIP concentrations were positively associated with BMD at the FN, lumbar spine 1-4, and total hip. We also observed that serum VIP levels were positively correlated with E2 levels but negatively correlated with IL-1ß and TRCAP-5 levels. In addition, ROC analysis found that reduction of serum VIP in combination with elevation of TRACP-5b may serve as an indicator of a severe Genant grade. Conclusions: Attenuated serum VIP levels were linked to disease severity of PMOP and may act as a protective marker for PMOP.