s / Osteoarthritis and Cartilage 21 (2013) S63–S312 S230 were significantly decreased in the severity of the OA-like changes. The level of microtubule-associated protein 1 light chain 3 (LC3), a main marker of autophagy, was increased in articular cartilage of Bach1-/mice compared with wild-type mice. The rate of apoptotic chondrocytes in Bach 1-/mice was lower than that of wild-type mice. Conclusions: Bach1-/mice reduces the severity of age-related OA-like changes by activation of autophagy and anti-apoptosis. The maintenance of HO-1 expression may play an important role in a protective effect or homeostasis in joints. These results suggest that autophagy via HO-1 is a novel mechanism in OA prevention. The inducer of HO-1 may be an effective therapeutic molecule for OA prevention. 433 DEVELOPMENT OF OSTEOARTHRITIS AND DISRUPTION OF KNEE JOINT MORPHOLOGY IN A CARTILAGE SPECIFIC MITOGEN INDUCIBLE GENE 6 DELETION MOUSE M. Pest y, J.-W. Jeong z, F. Beier y. yWestern Univ. Canada, London, ON, Canada; zMichigan State Univ., Grand Rapids, MI, USA Introduction: Osteoarthritis (OA) is a degenerative joint disease afflicting over 1 in 10 individuals in Canada. Current treatments focus on relief of pain and disability, rather than slowing or reducing the underlying joint damage. Previous studies by our lab have shown that the signalling molecule transforming growth factor alpha (TGFa) is upregulated in both animal models of OA and in a subset of human cases (Appleton et al, 2007;2010). TGFa signals via epidermal growth factor receptor (EGFR) in chondrocytes. Mitogen-inducible gene 6 (MIG6) has been shown to attenuate signalling by EGFR through blockade of autophosphorylation and induction of receptor internalization. Ubiquitous deletion of MIG-6 in mice causes the rapid development of joint deformities and OA (Zhang et al, 2005; Jin et al, 2007), however it is not known which cell type is responsible for these defects. Purpose: To assess the consequences of increased EGFR signalling specifically in cartilage by removing negative regulation via MIG-6 using a transgenic in vivo mouse KO model. Methods: MIG-6 was selectively knocked out in cartilage using floxed transgenic mice (MIG-6fl/fl) by the Col2a1 driven expression of Cre (Col2-Cre+/-). Animals were kept on a normal diet and unregulated activity levels. Littermate matched controls were used in all experiments. Male and female mice were aged up to one year to assess spontaneous development of OA and joint deformation. Behavioural changes indicative of joint pain and disability were assessed through gait analysis and grip strength measurement. Evaluation of bone density and structural abnormalities in articular joints was accomplished throughmicroCT scanning and histological staining. OA severity was scored using a modified OARSI scoring system on safranin O/fast green stained sections of knee, ankle and elbow joints. Molecular changes in joint tissues were also examined by immunohistochemistry. Results: In both male and female KO (MIG-6fl/fl;Col2-Cre+/-) knee joints, extensive joint deformitieswere observed includingectopic development of partially calcified tissues. These deformations became more severe with the increasing age of the animals. Both Het (MIG-6fl/+;Col2-Cre+/-) and WT (MIG-6fl/fl;Col2-Cre-/or MIG-6fl/wt;Col2-Cre-/-) controls did not show evidence of joint deformity by visual inspection or microCT scans. KO, HETandWTanimalswere not significantly different in size orweight. Conclusions: Negative regulation of EGFR signalling in Col2 expressing tissues by MIG-6 is essential for management of normal joint morphology and may be involved in the regulation of tissue calcification. MIG-6 is a promising molecule for studies evaluating the underlying causes of spontaneous OA and joint deformation, and may be a viable target for therapeutic interventions in OA. 434 FOCAL CHANGES IN TIBIAL BONE STRUCTURE AND OSTEOCYTE INTEGRITY IN A MOUSE SURGICAL MODEL OF OSTEOARTHRITIS B.A. Tonkin y, N. Jansz y, E. Romas z, N.A. Sims y, N.C. Walsh y. y St Vincent's Inst. of Med. Res., Melbourne, Australia; zDept of Rheumatology, St Vincent's Hosp., Melbourne, Australia Purpose: Inflammation is integral to cartilage damage and bone erosion observed in joints afflicted with osteoarthritis (OA). We have earlier reported that physiologic levels of exercise are anti-inflammatory and suppress local inflammation in joints in experimental models of OA in vivo. The abrogation of pro-inflammatory signals by mechanical stimulation is mediated by suppression of NF-kB activity. Here we examined whether the observed effects of physiological levels of exercise are mediated via its local or systemic actions on inflammation. Methods: All protocols were preapproved by the Institutional Animal Care and Use Committee at OSU. Transgenic BALBc female mice (12-14 wks old) containing firefly luciferase cDNA in NF-kB response elements (NFkB-RE-luc mice; Caliper Life Sciences, MA) were used to study transcriptional regulation of the NF-kB gene to examine the effects of exercise (treadmill walking at 8 M/min) on inflammation. Inflammationwas triggered by injection of lipopolysaccharide (LPS; 1 mg/gm body weight) or IL-1b (10 -50 ng/30 g body weight) in the right ankle of mice. Mice received following treatments, (i) no treatment (ii) exercise alone, (iii) LPS injection alone, (iv) pre-exercised for 7 days prior to induction of inflammation, (v) exercised only post induction of inflammation, or (vi) exercised pre and post induction of inflammation. Activation of NF-kB was assessed 2 hrs, 24 hrs, 48 hrs or 5 days post induction of inflammation by examining luciferase activity by digital imaging (IVIS 100). The induction of proinflammatory cytokines in the serum samples of the same mice was assessed by Multiplex ELISA assays (Biorad Labs, CA). Results: Control NFkB-RE-luc mice and those exposed to exercise alone did not exhibit significant NF-kB activation. LPS injection in right ankle provoked a systemic and local inflammatory response that was 6-8 fold greater within 2 hours of LPS administration. Mice exposed to exercise 7 days prior to LPS injection showed a significant systemic inhibition of LPS-induced NF-kB activation. However, mice exposed to exercise following LPS injection showed more than 90% suppression of NF-kB activation. These observations indicated that exercise is an important systemic inhibitor of inflammation and its actions are mediated via suppression of NF-kB activity (Figure 1). Further analysis of NF-kB activation revealed that LPS activated NF-kB predominately in axillary and inguinal lymph nodes, spleen and mesentery. Examination of individual lymph nodes showed that exercise was effective in suppressing LPS-induced NF-kB activation in all of these lymph nodes and the site of injection. Further immunofluorescence analysis of NF-kB in all of these tissue confirmed that exercise inhibited NF-kB nuclear translocation and its synthesis. To gain molecular insight into the signaling affected by inactivation of NF-kB, we assessed the cytokine levels in the serum levels that follow NF-kB activation. Assessment of major pro-inflammatory cytokines IL1b, TNF-a, IL-6, IL-17, IL-12 and IL-8 all showed up-regulation by LPS, whereas pre-exercise and post-exercise both effectively suppressed proinflammatory cytokine induction. More importantly, the suppressive effects of post-exercise were more dramatic than pre-exercise. The above findings prompted us to examine whether the anti-inflammatory effects of exercise are sustained and for how long. In these experimentsmicewere eitherexercised everydayoronly for onedaypost LPS administration. Mice exposed to exercise every day demonstrated sustained suppression of NF-kB activation. However, the suppressive effects of exercise were transient, lasting only 24 h following exercise. Conclusions: The findings suggest that exercise may not only suppress local inflammation of the joints, but its effects may also be systemic through global inhibition of NF-kB activation in leukocytes following acute inflammation.