Using ¹⁸F-FDG microPET imaging to measure the inhibitory effects of Clematis chinensis Osbeck on the pro-inflammatory and degradative mediators associated with inflammatory arthritis

Aim of the study: This study examined the modulating effects of Clematis chinensis Osbeck (Ranunculaeae) on pro-inflammatory and degradative mediators associated with inflammatory arthritis. Materials and methods: Primary human chondrocytes (PHC) were stimulated with IL-1β or lipopolysaccharide (LPS) to induce the enhanced release of prostaglandin E₂ (PGE₂), metalloproteinase (MMP-3 and -13), and cyclooxygenase-2 (COX-2) protein expression. The ¹⁸F-FDG microPET imaging system was used to evaluate the anti-arthritic effects of Clematis chinensis in vivo. Results: The acetone extracted Clematis chinensis (CC6) contained the most total saponins compared to other solvent's extracts and showed significant and dose-dependent inhibitory effects on PGE₂, MMP-3, -13, and COX-2 productions by LPS-stimulated PHC. Furthermore, CC6 also exerted inhibitory effects on 2-¹⁸F- fluoro-2-deoxy-d-glucose (¹⁸F-FDG) uptake when assessed by positron emission tomography (PET) uptake in the joints and serum PGE₂ of rabbits with knee joints injected with LPS. Conclusion: The results suggest the significant chondroprotective effects of Clematis chinensis are through its anti-inflammatory and MMPs inhibitory abilities. Meanwhile, we established a new analysis method to evaluate the Chinese herbal anti-arthritic effects.