TNF and Arthritis: The difference in expression of Thbs1 was more pronounced in sorted CD11b+Gr-1+ cells, while strain-specific and disease-related differences were less pronounced in joint tissue extracts, pointing to other cellular sources of Thbs1. To further distinguish which of differentially expressed genes have a potential role in the pathogenesis of arthritis, we analyzed associations of candidates with knee joint diameters, and expression of proinflammatory cytokines IL-1β, tumor necrosis factor α (TNFα), and IL-6 in the knees of wt mice.