Serum S100 Proteins as a Marker of Disease Activity in Large Vessel Vasculitis.

BACKGROUND/OBJECTIVES: Serum S100A8/S100A9 and S100A12 levels have been shown to be elevated in giant cell arteritis (GCA). This study aimed to determine if levels of serum S100 proteins perform as markers in a comparable fashion to standard markers of disease activity in large-vessel vasculitis.

METHODS

Serum samples were obtained from the Vasculitis Clinical Research Consortium (VCRC) Longitudinal Prospective Cohort Study of GCA and Takayasu’s arteritis (TAK). A mixed effects model compared S100 proteins during active and inactive disease states. Receiver operating characteristic curves compared models using S100 proteins to models using ESR and CRP.

RESULTS

There were 106 samples (50 during active disease) from patients with GCA and 32 samples (16 during active disease) from patients with TAK. In GCA, S100A8/S100A9 and S100A12 were significantly elevated during active disease (1445.6 ng/mL vs. 1095.7 ng/mL, p = 0.003;163.2 ng/mL vs. 116.6ng/mL, p=0.016, respectively). There were weak correlations between levels of S100 proteins and ESR or CRP. A model including S100A8/S100A9, S100A12, ESR, and CRP was a better indicator of disease activity compared to ESR and CRP together. In TAK, there were no significant differences between active and inactive disease for either the S100 proteins or ESR/CRP.

CONCLUSIONS

Serum levels of S100A8/S100A9 and S100A12 are elevated during active disease and perform comparably to ESR and CRP as measures of disease activity in giant cell arteritis.