POS1133 IRISIN LEVELS IN KNEE OSTEOARTHRITIS ARE RELATED TO GENDER, OBESITY AND LOCAL INFLAMMATION

Abstract

BackgroundIrisin is a myokine synthesized mainly in skeletal muscle with exercise, although its secretion has also been observed in other tissues such as adipose and has been related to obesity and other metabolic alterations. Although obesity and other metabolic factors are risk factors for knee osteoarthritis and patients with this condition often do less exercise and have poor muscular state, irisin has been poorly studied.ObjectivesTo measure irisin levels in synovial fluid and plasma and evaluate their relationship with clinical severity and inflammation parameters in patients with knee osteoarthritis.MethodsPatients with symptomatic and radiographical osteoarthritis were studied. Demographic and anthropometric variables, Kellgren-Lawrence scale radiographic stage, the presence of synovial fluid and hypertrophy on ultrasound (at medial patellar line), clinical severity by Lequesne algofunctional index and physical exercise level were recorded. Levels of irisin, IL-6, TNF and hs-PCR were determined using ELISA.ResultsWe included 168 women (age 69 ±1.5 y, symptoms duration 48 ±3 m) and 31 men (age 66.5 ±4 y, symptoms duration 36 ±12 m). Significantly higher levels of irisin in synovial fluid were observed in women who did not perform any physical exercise compared to those who did exercise sporadically or regularly (p.0.05), while in plasma a non-significant trend was observed. A weakly positive correlation between intraarticular levels (r= 0.17, p .0.05) and plasma levels (r= 0.16, p. 0.05) of irisin and Lequesne index in women was also evidenced. Regarding inflammatory parameters, in female patients the synovial levels of irisin presented a weak positive correlation with the synovial levels of IL-6 (r= 0.18, p< 0.05) but not in plasma; an association was also found in women between synovial levels of irisin and synovial fluid >8 mm and severe synovial hypertrophy (p<0.05) in women, but not with plasma levels. All significant associations disappeared when adjusting by IMC except in the case of synovial hypertrophy. No statistically significant results were obtained in men.ConclusionLevels of irisin are related to gender and obesity in patients with knee osteoarthritis. However, the association with the intraarticular levels of IL-6 and the synovial hypertrophy could point to a possible local inflammatory effect at intraarticular level.Disclosure of InterestsNone declared