THU0152 Serum presepsin as a novel biomarker for bacterial infection in rheumatoid arthritis patients treated with tocilizumab

Background Tocilizumab (TCZ), an inhibitor of interleukin-6 (IL-6), has been widely used to treat rheumatic diseases such as rheumatoid arthritis (RA) and juvenile idiopathic arthritis. Recently, TCZ was approved for use in patients with giant cell aortitis and Takayasu aortitis. However, TCZ treatment sometimes obscures changes in the conventional biomarkers for infection such as serum levels of C-reactive protein (CRP) and procalcitonin (PCT). Presepsin (P-SEP), a subtype of soluble CD14, has been recently identified as a biomarker for sepsis. In addition, we have reported the usefulness of P-SEP for the diagnosis of bacterial infection in RA patients because it is less affected by the disease activity. Objectives To examine the usefulness of P-SEP in RA patients complicated with bacterial infections during TCZ treatment. Methods In this study, 49 RA patients with bacterial infections (i+RA), 76 RA patients without bacterial infections (RA) and 23 healthy controls (HC) were enrolled. The presence of infection was strictly diagnosed by bacteriological examinations, typical clinical characteristics such as fever (38.0°C) and/or CRP elevation and/or increased white blood cell count, and improvements of these manifestations with antibiotics. Serum P-SEP levels were measured by an immunoassay. The CRP and PCT levels were measured simultaneously. Results The median serum P-SEP levels were 186.0 [interquartile range (IQR), 134.0–236.0], 691.0 [IQR, 345.5–842.0], 154.5 [IQR, 145.8–165.5] l, and 161.0 [IQR, 146.5–166.0] pg/mL for TCZ (n=25), i+TCZ (pre-antibacterial treatment; n=7), i+TCZ (post-antibacterial treatment; n=7) and the HC group, respectively. The P-SEP levels of the i+TCZ group were significantly elevated compared with those of the TCZ group (p Conclusions These results suggest that serum P-SEP levels are less affected by TCZ treatment compared with other conventional inflammatory biomarkers such as CRP and PCT. Moreover, P-SEP levels are useful for the assessment of bacterial infections in RA patients treated with TCZ. Reference [1] Tsuji S, et al. Mod Rheumatol2017;27(4):718–720. Disclosure of Interest None declared