Non-invasive monitoring of arthritis treatment response via targeting of tyrosine-phosphorylated annexin A2 in chondrocytes.

BACKGROUND: The development and optimization of therapies for rheumatoid arthritis (RA) is currently hindered by a lack of methods for early non-invasive monitoring of treatment response. Annexin A2, an inflammation-associated protein whose presence and phosphorylation levels are upregulated in RA, represents a potential molecular target for tracking RA treatment response. METHODS: LS301, a near-infrared dye-peptide conjugate that selectively targets tyrosine 23-phosphorylated annexin A2 (pANXA2), was evaluated for its utility in monitoring disease progression, remission, and early response to drug treatment in mouse models of RA by fluorescence imaging. The intraarticular distribution and localization of LS301 relative to pANXA2 was determined by histological and immunohistochemical methods. RESULTS: In mouse models of spontaneous and serum transfer-induced inflammatory arthritis, intravenously administered LS301 showed selective accumulation in regions of joint pathology including paws, ankles, and knees with positive correlation between fluorescent signal and disease severity by clinical scoring. Whole-body near-infrared imaging with LS301 allowed tracking of spontaneous disease remission and the therapeutic response after dexamethasone treatment. Histological analysis showed preferential accumulation of LS301 within the chondrocytes and articular cartilage in arthritic mice, and colocalization was observed between LS301 and pANXA2 in the joint tissue. CONCLUSIONS: We demonstrate that fluorescence imaging with LS301 can be used to monitor the progression, remission, and early response to drug treatment in mouse models of RA. Given the ease of detecting LS301 with portable optical imaging devices, the agent may become a useful early treatment response reporter for arthritis diagnosis and drug evaluation.

Fumagillin prodrug nanotherapy suppresses macrophage inflammatory response via endothelial nitric oxide.

Antiangiogenesis has been extensively explored for the treatment of a variety of cancers and certain inflammatory processes. Fumagillin, a mycotoxin produced by Aspergillus fumigatus that binds methionine aminopeptidase 2 (MetAP-2), is a potent antiangiogenic agent. Native fumagillin, however, is poorly soluble and extremely unstable. We have developed a lipase-labile fumagillin prodrug (Fum-PD) that eliminated the photoinstability of the compound. Using αvß3-integrin-targeted perfluorocarbon nanocarriers to deliver Fum-PD specifically to angiogenic vessels, we effectively suppressed clinical disease in an experimental model of rheumatoid arthritis (RA). The exact mechanism by which Fum-PD-loaded targeted nanoparticles suppressed inflammation in experimental RA, however, remained unexplained. We herein present evidence that Fum-PD nanotherapy indirectly suppresses inflammation in experimental RA through the local production of endothelial nitric oxide (NO). Fum-PD-induced NO activates AMP-activated protein kinase (AMPK), which subsequently modulates macrophage inflammatory response. In vivo, NO-induced AMPK activation inhibits mammalian target of rapamycin (mTOR) activity and enhances autophagic flux, as evidenced by p62 depletion and increased autolysosome formation. Autophagy in turn mediates the degradation of IkappaB kinase (IKK), suppressing the NF-κB p65 signaling pathway and inflammatory cytokine release. Inhibition of NO production by N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, reverses the suppression of NF-κB-mediated inflammatory response induced by Fum-PD nanotherapy. These unexpected results uncover an activity of Fum-PD nanotherapy that may be further explored in the treatment of angiogenesis-dependent diseases.