Interestingly, we observed that IAR convertors displayed higher levels of CRP (p < 0.01), SAA (p < 0.01), Leptin (p = 0.09) and PP (p < 0.05) (Supplementary Fig. 4), when compared to individuals that did not convert, thus displaying levels like the one observed in established seropositive RA patients. Here, PPY is linked to rheumatoid arthritis.