Fig. 4

Delayed-type hypersensitivity arthritis (DTHA) is accompanied by enhanced proteolytic osteoclast activity and increased transcription of genes associated with bone erosion and new bone formation. a Activity of the tissue-remodeling enzyme cathepsin B (CatB; mean and individual measurements, n = 3–5) at indicated time points after arthritis induction in the methylated bovine serum albumin–challenged paw with subtracted fluorophore intensity of the control paw as determined by in vivo fluorescence molecular tomographic imaging. b Serum levels (mean ± standard error of the mean, n = 5–10) of matrix metalloproteinase 3 (MMP3) over the course of DTHA is shown. Dashed line represents the mean of naive mice (n = 5). c Messenger RNA (mRNA) expression of genes associated with bone destruction (mean and individual measurements, n = 4) in paw tissue as determined by mRNA deep sequencing. Significance of differences in levels in naive mice was determined using one-way analysis of variance (ANOVA) with Dunnett’s posttest for multiple comparisons. *p < 0.05; **p < 0.01; ***p < 0.001. d mRNA expression of genes associated with bone formation and tissue remodeling in paw tissue as determined by mRNA deep sequencing (mean and individual measurements, n = 4). Significance of differences in levels in naive mice was determined using one-way ANOVA with Dunnett’s posttest for multiple comparisons. *p < 0.05; **p < 0.01; ***p < 0.001. BMP bone morphogenetic protein; RANKL receptor activator of nuclear factor κB ligand, RPKM reads per kilobase per million reads, TRAP tartrate-resistant acid phosphatase, CatK cathepsin K, DKK-1 dickkopf 1, TGF-β1 transforming growth factor β1