PO:33:192 | Hand Microvascular Damage Is Associated with Hand Bone Loss in Systemic Sclerosis

Rosanna Campitiello^1|3, Sabrina Paolino^1|2, Andrea Casabella^1|2, Giulia Davoli^1|2, Elisa Caratto^1|2, Emanuele Gotelli^1|2, Elvis Hysa^1|2, Carmen Pizzorni^1|2, Vanessa Smith^4|5, Alberto Sulli^1|2, Maurizio Cutolo^1|2 | ¹1. Laboratory of Experimental Rheumatology and Academic Division of Clinical Rheumatology, Department of Internal Medic Genova, Italy; ²IRCCS Ospedale Policlinico San Martino Genova, Italy; ³Department of Experimental Medicine DIMES, University of Genova Genova, Italy; ⁴Department of Internal Medicine and Department of Rheumatology, Ghent University ^Hospital Ghent, Belgium; ⁵Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Centre, Ghent, Belgium

Aim. Systemic sclerosis (SSc) is a rare autoimmune disease marked by vascular dysfunction, immune dysregulation, and progressive fibrosis1. Previous studies have shown that patients (pts) with SSc exhibit more pronounced micro- and macroarchitectural bone damage compared to healthy subjects (HS) and severe microvascular damage has been linked to compromised bone integrity2,3. This highlights the extent of localized hand bone loss and possible association to local microvascular dysfunction in SSc. To investigate the relationship between hand bone quality and peripheral microvascular status in pts with SSc, using nailfold videocapillaroscopy (NVC).

Methods. Bone mineral density (BMD) (measured in g/cm2) and bone mineral content (BMC) (measured in g) of the dominant hand and total skeleton were measured in 32 pts with SSc (mean age 61 ± 14 years, 94% women) and 30 age-matched HS using a new dedicated software for the hands (enCore, GE Lunar Prodigy Bone Densitometer, BMD hand software, USA). Pts were classified with limited or diffuse cutaneous SSc according to the 2013 ACR/EULAR criteria (47% dcSSc). Microvascular involvement was evaluated via standardized NVC analysis and capillary number scoring 4. SSc organ involvement was evaluated according to the EULAR guidelines5. Statistical analysis included non-parametric and logistic regression to explore the relationship between capillary density and hand bone status.

Results. Logistic regression analysis revealed a significant association between capillary loss and hand BMD in patients with SSc (R² = 0.3826, F = 17.35, p < 0.001).Clinical, laboratory and NVC correlations were performed and reported in Table I. In addition, hand bone values positively correlated with spinal (r = 0.4671, p = 0.007) and femoral measurements (neck r = 0.3866, p = 0.029; total femur r = 0.354, p = 0.047) in SSc pts. Notably, SSc pts showed significantly lower hand BMD and BMC compared to HS (BMD: 0.31 ± 0.07 vs. 0.39 ± 0.06, p < 0.01; BMC: 21.27 ± 7.32 vs. 30.09 ± 7.8, p < 0.01) even when adjusted for age, gender, BMI and history of osteoporosis; beta= -0.2234, p = 0.025).

Conclusions. Hand local bone status was found for the first time significantly associated with hand/fingers microvascular damage, and it was also found to be lower in SSc pts compared with HS. The data suggest that SSc-related microvascular insufficiency, as detected by NVC, may contribute to increased local bone deterioration. Further prospective studies are also evaluating the correlation between hand microcirculation analysis and more detailed hand bone changes.

References
1. Volkmann ER et al. Lancet 2023; 401(10371): 304–318; 2. Omair MA et al. J Rheumatol 2013; 40(11): 1881–1890; 3. Paolino S et al. J Endocrinol Invest 2021; 44(2): 255–264; 4. Smith V et al. Autoimmun Rev 2020; 19(3): 102458; 5. Kowal-Bielecka O, et al. Ann Rheum Dis. 2017;76(8):1327-1339.