LAUSR

HIGHLIGHTSLXA4 was rapidly elevated and reduced to normal level after treadmill exercise.There was no difference of LXA4 between moderate and high intensity treadmill exercise.Moderate‐intensity treadmill exercise ameliorate OA could be suppressed by BOC‐2.LXA4 could attenuate MMP‐3 and 13 induced by IL‐1&bgr; in FLSs via NF‐&kgr;B pathway.LXA4 could be a significant indicator to detect the effect of treadmill exercise on OA. ABSTRACT Lipoxin A4 (LXA4), a kind of adipokines, is a potent stop signal of inflammation. Our preliminary study found that LXA4 of serum and intra‐articular lavage fluid (IALF) was rapidly elevated in 2 h and rapidly reduced to normal level at 4 h after moderate‐intensity treadmill exercise. The aim was to confirm the therapeutic effects of LXA4 during treadmill exercise on rat model of monosodium iodoacetate (MIA)‐induced OA and the detailed mechanism of LXA4 on OA. One hundred and twenty‐four male Sprague‐Dawley rats were submitted to two different protocols. A single session of treadmill exercise: sixty‐four rats were randomly divided into treadmill exercise of different intensities for 60 min only once (n = 4). Formal treadmill exercise: sixty rats were randomly divided into six groups (n = 10): control group (CG), knee OA group (OAG), OA with treadmill exercise of different intensities (OAL, OAM and OAH), and OAM + BOC‐2 (an antagonist of LXA4 receptor). The rats were evaluated by ELISA, histology, immunohistochemistry and western blotting. Fibroblast‐like synoviocytes (FLSs) were obtained from knee joint of rats. The effects of LXA4 on interleukin (IL)‐1&bgr; induced FLSs were evaluated by western blotting and immunofluorescence. The results of ELISA, histological evaluation, western blotting and immunohistochemistry indicated that OAM had a better treatment which could be suppressed by BOC‐2. Moreover, LXA4 could attenuate the expression of matrix metalloproteinase (MMP)‐3 and MMP‐13 and suppress the expression of nuclear factor‐kappa B (NF‐&kgr;B) p65 induced by IL‐1&bgr; in FLSs. The therapeutic effects of LXA4 during treadmill exercise on MIA‐induced OA via inhibiting NF‐&kgr;B signaling pathway.