Quantification of cytokines and inflammatory mediators in a three-dimensional model of inflammatory arthritis

Human recombinant IL-1β and TNFα have been previously used to induce a cytokine response in canine chondrocytes. In order to establish this functional relation in a homologous system in vitro, we have developed both 2D and 3D models of inflammatory arthritis using canine recombinant cytokines in canine articular chondrocytes. IL-1β and TNFα were cloned and subsequently expressed in Escherichia coli. The purified recombinant canine cytokines were used to simulate inflammation in vitro and the expression of typical inflammation markers such as proinflammatory cytokines (IL-1β, IL-6, IL-8, GM-CSF and TNFα), enzyme mediators (MMP-3 MMP-13, iNOS, COX-2) and their catabolites (NO, PGE2) was measured. High expression of proinflammatory cytokines, enzyme mediators and their catabolites was only observed in IL-1β/TNFα stimulated cells. We conclude that the canine IL-1β and TNFα generated in this study are biologically active and equally effective in the canine cell culture systems. Inducing an inflammatory pathway by canine exogenous cytokines in canine chondrocytes provides a useful tool for the study of canine inflammatory arthritis.