Anti-inflammatory effects of IL-4 and dynamic compression in IL-1beta stimulated chondrocytes.

Mechanical loading can counteract inflammatory pathways induced by IL-1beta by inhibiting *NO and PGE2, catabolic mediators known to be involved in cartilage degradation. The current study investigates the potential of dynamic compression, in combination with the anti-inflammatory cytokine, IL-4, to further abrogate the IL-1beta induced effects. The data presented demonstrate that IL-4 alone can inhibit nitrite release in the presence and absence of IL-1beta and partially reverse the IL-1beta induced PGE2 release. When provided in combination, IL-4 and dynamic compression could further abrogate the IL-1beta induced nitrite and PGE2 release. IL-1beta inhibited [3H]thymidine incorporation and this effect could be reversed by IL-4 or dynamic strain alone or both in combination. By contrast, 35SO4 incorporation was not influenced by IL-4 and/or dynamic strain in IL-1beta stimulated constructs. IL-4 and mechanical loading may therefore provide a potential protective mechanism for cartilage destruction as observed in OA.