Fig. 1

IL-23 is required for zymosan-induced arthritic pain and optimal disease development as well as for zymosan-induced inflammatory pain. a, b WT and Il23p19^−/− mice received an intra-articular (i.a.) injection of zymosan. a Pain (incapacitance meter [ratio of weight bearing on injected relative to non-injected hindlimb]; a value less 100 indicates pain) and b arthritis (histology: H&E stain, Safranin O/Fast Green stain, day 7) were measured. Arrows indicate the following features, respectively: solid arrows, cellular infiltration; dotted arrows, bone erosion; and dashed arrows, proteoglycan loss. c, d WT and Il23p19^−/− mice received an intraplantar (i.pl.) injection of zymosan. c Paw swelling (× 10⁻² mm) and d pain (incapacitance meter) were measured over a 6-h period. Data are expressed as mean ± SEM; a–d WT and Il23p19^−/− male mice (saline, n = 10; zymosan, n = 10). For statistical analysis, a two-way ANOVA for pain and a Mann-Whitney test for histology were used. *P < 0.05, **P < 0.01, ***P < 0.01, ****P < 0.0001, WT vs. Il23p19^−/− mice