Background and purpose
The pathogenesis of osteoarthritis implicates a low-grade inflammation associated to the innate immune system activation. Toll like receptor (TLR) stimulation triggers the release of inflammatory mediators, which aggravate osteoarthritis. We studied the preventive effect of 6-shogaol, a potential TLR4 inhibitor, on the treatment of experimental knee osteoarthritis. Experimental approach: Osteoarthritis was induced in C57BL6 mice by surgical section of the medial meniscotibial ligament, which received 6-shogaol for eight weeks. Cartilage damage, inflammatory mediator presence and disease markers were assessed in joint tissues by immunohistochemistry. Computational modelling was used to predict binding modes of 6-shogaol into the TLR4/MD2 receptor and its permeability across cellular membranes. Employing LPS-stimulated chondrocytes and MAPK assay, we elucidated 6-shogaol action mechanisms. Key
Purpose
The pathogenesis of osteoarthritis implicates a low-grade inflammation associated to the innate immune system activation. Toll like receptor (TLR) stimulation triggers the release of inflammatory mediators, which aggravate osteoarthritis. We studied the preventive effect of 6-shogaol, a potential TLR4 inhibitor, on the treatment of experimental knee osteoarthritis. Experimental approach: Osteoarthritis was induced in C57BL6 mice by surgical section of the medial meniscotibial ligament, which received 6-shogaol for eight weeks. Cartilage damage, inflammatory mediator presence and disease markers were assessed in joint tissues by immunohistochemistry. Computational modelling was used to predict binding modes of 6-shogaol into the TLR4/MD2 receptor and its permeability across cellular membranes. Employing LPS-stimulated chondrocytes and MAPK assay, we elucidated 6-shogaol action mechanisms. Key
Results
6-Shogaol treatment prevented articular cartilage lesions, synovitis and the presence of pro-inflammatory mediators, and disease markers in osteoarthritis animals. Molecular modelling studies predicted 6-shogaol interaction with the TLR4/MD-2 heterodimer in an antagonist conformation through its binding into the MD-2 pocket. In cell culture, we confirmed that 6-shogaol reduced LPS-induced TLR4 inflammatory signalling pathways. Besides, MAPK assay demonstrated that 6-shogaol directly inhibits the ERK1/2 phosphorylation activity.