AB0057 Decreased irisin level as risk factor of pathological fractures in rheumatoid arthritis patients
Authors: D. Lavrova, B. Zavodovsky, L. Sivordova, Y. Akhverdyan, Y. Polyakova, A. Yakovlev
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Recent studies have been suggested that adipokines and myokines may be implicated in bone metabolism and pathogenesis of osteoporosis (OP).<sup>1</sup> Previous studies have revealed inverse correlation between irisin levels and vertebral fragility fractures, but no significant correlation was found between irisin and bone mineral density (BMD) as well as with lean weight. There is no previously published data about irisin levels in rheumatoid arthritis (RA) patients.<sup>2–4</sup> <h3>Objectives</h3> To investigate serum irisin levels in patients with RA. <h3>Methods</h3> We studied 170 people: 110 RA patients (mean age 53.58±12.32; hereinafter M±SD) and 60 healthy controls. All patients with RA were examined using dual-energy X-ray absorptiometry using LUNAR DPX-Pro densitometer. Osteoporotic fractures were confirmed by X-ray examination and/or by anamnesis data. All patients were passed through extensive clinical and laboratory examination, including N-terminal propeptide of procollagen type I, C-telopeptide of type I collagen, 25(OH)-vitamin D concentration. Serum irisin levels were measured by ELISA (BioVender test system, Cat №RAG018R). <h3>Results</h3> The mean concentration of irisin in RA group was 14.48±7.07 mg/ml, which was significantly lower than of healthy donors – 20.49±4.82 mg/ml (p&lt;0,001). We subsequently divided all of RA patients into two groups: the first one (n=44) included patients with reduced serum irisin levels (below 10.85 mg/mL), and the second one (n=66) with normal irisin levels (above 10.85 mg/ml). The first group had significantly higher activity (DAS28), increased frequency of extra-articular manifestations, disease duration more than 5 years, class III of functional joints disability and lower levels of 25(OH)-vitamin D. We also observed higher incidence of pathological bone fractures in this group (p=0,047). There wasn't any significant correlation between serum irisin level and BMD at any localization, lean, or fat weight. We did not reveal any difference of bone turnover markers (serum C-terminal telopeptide of type I collagen, serum N-terminal propeptide of type I procollagen (P1NP)) between these groups. <h3>Conclusions</h3> We have therefore revealed relationships between decreased serum irisin levels, 25(OH)-vitamin D concentration and higher incidence of pathological bone fractures in RA patients. We found no connexion between serum irisin levels and BMD at any site and body composition. We could consequently suppose, that irisin levels may reflect bone quality or increased fall risk. <h3>References</h3> [1] Palermo A, Strollo R, Maddaloni E, et al. Irisin is associated with osteoporotic fractures independently of bone mineral density, body composition or daily physical activity. Clin Endocrinol (Oxf)2015;82(4):615–9. [2] Boström P, Wu J, Jedrychowski MP, et al. A PGC1-α-dependent myokine that drives brown-fat-like development of white fat and thermogenesis. Nature2012;481(7382):463–8. [3] Colaianni G, Cuscito C, Mongelli T, et al. Irisin enhances osteoblast differentiation in vitro. Int J Endocrinol2014;2014:902186. [4] Sivordova LE, Zavodovsky BV, Polyakova JV, et al. Adiponectin as a useful marker for diagnosis of osteoporosis in rheumatoid arthritis patients. Osteoporosis Int. 2016;27(S.1):135. <h3>Disclosure of Interest</h3> None declared