Correlation between bone quality and microvascular damage in systemic sclerosis patients.

Objectives: SSc patients are recognized as presenting an increased risk of altered bone mass. The aim of this study was to assess the bone quality, by trabecular bone score (TBS), in SSc patients in correlation with different levels of microvascular damage, as evaluated by nailfold videocapillaroscopy (NVC), and to compare the results regarding bone quality with RA patients and healthy subjects (CNT). Methods: Eighty-four SSc patients, 98 RA patients and 60 CNT, were studied. BMD (g/cm2) of the lumbar spine (L1-L4) was analysed by DXA scan. Lumbar spine bone quality was derived from each spine DXA examination using the TBS analysis. NVC patterns were analysed. Results: A total of 56/84 SSc patients (66%) as well as 78/98 RA patients (80%) showed bone loss at DXA and BMD was found to be significantly lower than in the CNT (P < 0.001). Similarly, lumbar spine TBS was found to be significantly lower in SSc and RA patients than in CNT (P < 0.001). TBS values were found to be lower in SSc with a late NVC pattern, compared with the active or early pattern (late vs active and early pattern, P < 0.001). There was no statistically significant difference in the mean lumbar spine TBS between SSc and RA patients (P = 0.238). Conclusion: The data obtained showed significantly lower bone quality (lower TBS and BMD) in SSc and RA patients compared with CNT. The bone quality seemed lower in SSc patients with more altered microvasculature (late NVC pattern).

Dickkopf-1 (Dkk-1) serum levels in systemic sclerosis and rheumatoid arthritis patients: correlation with the Trabecular Bone Score (TBS).

The aim of this research was to determine any correlations between Dickkopf-1 serum levels (Dkk-1, a natural inhibitor of the Wnt signaling pathway promoting osteoclastogenesis) and the Trabecular Bone Score (TBS), in systemic sclerosis (SSc) and rheumatoid arthritis (RA) patients. It also aimed at determining any difference in Dkk-1 serum levels between SSc and RA patients and a control group (CNT) of healthy subjects. A prospective study was carried out in 60 SSc and 60 RA patients and 60 CNT. Dkk-1 serum levels were evaluated by the ELISA method (Quantikine Human Dkk-1 Immunoassay, R&D System, Minneapolis, USA). The severity of microvascular damage was evaluated by nailfold videocapillaroscopy (NVC patterns: "Early," "Active," "Late"), in the SSc patients. TBS analysis and bone mineral density (BMD, g/cm2) were measured in all patients/subjects. The SSc patients showed higher Dkk-1 serum levels than RA (p < 0.004) and CNT (p < 0.0001) patients. SSc patients, showing the "Late" NVC pattern had statistically higher Dkk-1 serum levels than patients with either the "Active" or "Early" (p < 0.004) patterns. Only in the "Late" NVC pattern group of SSc patients was there a significant negative correlation between Dkk-1 and TBS values (p < 0.0001). The increased Dkk-1 serum levels and decreased TBS values observed suggest a diffuse bone damage in SSc patients with advanced disease, as demonstrated by the concomitant presence of the "Late" NVC pattern. Moreover, the bone remodeling in SSc seems even higher than that in RA patients.