After adjustment for urine creatinine, urinary levels of the three cytokines (IL-6, CCL2, and IL-8) (n = 173) were significantly higher in RA patients than in non-RA control subjects (n = 62) (Fig. 1A,C), which concurs with our previous report demonstrating that RA patients have inflammatory urine9. This evidence concerns the gene CXCL8 and rheumatoid arthritis.