THU0486 The vitamin d receptor expression in skeletal muscle of women with distal radius fracture

Abstract

BackgroundA distal radius fracture (DRF) is the most common upper extremity fracture in old women. Since DRFs typically occur earlier than hip fractures by an average of 15 years, they can reflect early changes of bone such as osteoporosis and muscle frailty for instance, the loss of muscle mass.ObjectivesWe aimed to evaluate the relationship between the vitamin D receptor (VDR) expression in the muscle cell and the muscle mass in women with a DRF.MethodsThis research was conducted as a part of the Study on Ageing Radial fracture Cohort (SARCO) which is an ongoing longitudinal, population-based cohort investigation of patients with a DRF which began in November 2015. For the current study, we prospectively recruited 45 women over 50 years of age (mean age, 66 years) with DRF and acquired biopsy of the forearm flexor muscle. The muscle cross-sectional area (CSA) and VDR expression were measured using immunohistochemistry staining. The clinical parameters including grip strength, gait speed, body mass index (BMI), bone mineral density (BMD), and serum vitamin D levels were compared between patients grouped by appendicular lean mass index and were correlated with the VDR expression.ResultsTwelve patients (27%) showed a decreased appendicular lean mass index, less than the cut-off value of 5.4 kg/m2 which was suggested by the Asian Working Group for Sarcopenia. Patients with a low appendicular lean mass index had significantly lower muscle CSA (p=0.037), but a higher VDR expression (p=0.045) than those with higher indices. VDR expression was negatively correlated with BMI (r=−0.417, p=0.004) and appendicular lean mass index (r=−0.316, p=0.044).ConclusionsDRF patients with low appendicular lean mass index presented high VDR expression and low CSA in forearm muscle cells. This suggests that the VDR expression might be up-regulated in the attempt to compensate for the decreasing muscle mass. Further studies are necessary to explore the role of VDR in the progression of sarcopenia.References[1] Ceglia L, Harris SS. Vitamin D and its role in skeletal muscle. Calcif Tissue Int2013;92(2):151–162.[2] Bischoff-Ferrari H, Borchers M, Gudat F, Dürmüller U, Stähelin H, Dick W. Vitamin D receptor expression in human muscle tissue decreases with age. J Bone Miner Res2004;19(2):265–269.[3] Frontera WR, Reid KF, Phillips EM, Krivickas LS, Hughes VA, Roubenoff R, Fielding RA. Muscle fiber size and function in elderly humans: a longitudinal study. J Appl Physiol2008;105(2):637–642.Disclosure of InterestNone declared