Blocking IL-6R alleviates polyarthritis and joint inflammation in DNase II^−/−STING^S365A/S365A mice. (A–C) 6-wk-old DNase II^−/−STING^S365A/S365A female mice received rat IgG or anti–IL-6R (100 µg/g body weight) once i.v., followed by i.p. treatment of antibodies (25 µg/g body weight) once a week (n = 5 in each treatment group). (A) Arthritis scores (mean ± SD, n = 5 per group). Statistical analysis was done using a two-tailed, unpaired Student’s test. *, P < 0.05 between rat IgG– and anti–IL-6R–treated mice. (B) Incidence rates of arthritis (n = 5 per group). (C) qRT-PCR analysis of inflammatory cytokines in mouse paws (mean ± SD, n = 5 in each group). Each dot represents a mouse. (D and E) 5-mo-old male DNase II^−/−STING^S365A/S365A mice displaying polyarthritis received rat IgG or anti–IL-6R (100 µg/g body weight) once, followed by i.p. treatment of antibodies (25 µg/g body weight) once a week (n = 4 in each group). (D) Arthritis scores. *, P < 0.05 between rat IgG– and anti–IL-6R–treated mice. (E) qRT-PCR analysis of inflammatory cytokines in mouse paws (mean ± SD, n = 4 per group). Statistical analysis was done using a two-tailed, unpaired Student’s test. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001. Results are representative of two independent experiments. Ct, cycle threshold.