Figure 2.

Synovial expression of IL-33 during KBxN serum transfer-induced arthritis. (A) Clinical scores for inflammation of the left hind paw, which was processed for RNA extraction are shown (left panel), along with expression levels for IL-6 (middle panel) and IL-33 (right panel) mRNAs in the joint. Transcript levels were normalized relative to Gapdh expression and represent the mean ± SEM for WT C57BL/6 (n = 14, open columns), IL-33 KO (n = 12, gray columns), and ST2 KO (n = 10, black columns) mice. (B) Clinical scores for inflammation of the right forepaw, which was processed for protein extraction are shown (left panel), along with IL-6 (middle panel) and IL-33 (right panel) protein expression levels in the joint. Cytokine production was normalized to total protein content and represents the mean ± SEM for WT C57BL/6 (n = 14, open columns), IL-33 KO (n = 12, gray columns), and ST2 KO (n = 10, black columns) mice. (C) IL-33 protein expression (nuclear brown staining) was assessed in the synovium of arthritic knee joints of WT (left panel), IL-33 KO (middle panel) and ST2 KO (right panel) mice by immunohistochemistry (IHC) (original magnifications x200). Nuclear IL-33 staining was observed in WT and ST2 KO mice in cells morphologically consistent with fibroblasts (arrows), as well as in other cell types, which were not formally identified (arrowheads). KO, knockout; WT, wild-type.