PT - JOURNAL ARTICLE AU - Carlos Machahua AU - Sabina A. Guler AU - Michael P. Horn AU - Lurdes Planas-Cerezales AU - Ana Montes-Worboys AU - Thomas K. Geiser AU - Maria Molina-Molina AU - Manuela Funke-Chambour TI - Serum calprotectin as new biomarker for disease severity in idiopathic pulmonary fibrosis: a cross-sectional study in two independent cohorts AID - 10.1136/bmjresp-2020-000827 DP - 2021 Jan 01 TA - BMJ Open Respiratory Research PG - e000827 VI - 8 IP - 1 4099 - http://bmjopenrespres.bmj.com/content/8/1/e000827.short 4100 - http://bmjopenrespres.bmj.com/content/8/1/e000827.full SO - BMJ Open Resp Res2021 Jan 01; 8 AB - Background Non-invasive biomarkers for the assessment of disease severity in idiopathic pulmonary fibrosis (IPF) are urgently needed. Calprotectin belongs to the S-100 proteins produced by neutrophils, which likely contribute to IPF pathogenesis. Calprotectin is a well-established biomarker in inflammatory bowel diseases. In this cross-sectional study, we aimed to establish the potential role of calprotectin as a biomarker in IPF. Specifically, we hypothesised that patients with IPF have higher serum calprotectin levels compared with healthy controls, and that calprotectin levels are associated with disease severity.Methods Blood samples were obtained from healthy volunteers (n=26) and from two independent IPF cohorts (derivation cohort n=26, validation cohort n=66). Serum calprotectin levels were measured with a commercial kit adapted for that purpose and compared between healthy controls and patients with IPF. Clinical parameters, including forced vital capacity, diffusing capacity for carbon monoxide (DLCO) and the Composite Physiologic Index (CPI), were correlated with calprotectin serum levels.Results The IPF derivation cohort showed increased serum calprotectin levels compared with healthy controls (2.47±1.67 vs 0.97±0.53 µg/mL, p<0.001). In addition, serum calprotectin levels correlated with DLCO% predicted (r=−0.53, p=0.007) and with CPI (r=0.66, p=0.007). These findings were confirmed in an independent IPF validation cohort.Conclusion Serum calprotectin levels are significantly increased in patients with IPF compared with healthy controls and correlate with DLCO and CPI. Calprotectin might be a potential new biomarker for disease severity in IPF.All data relevant to the study are included in the article or uploaded as online supplemental information. Data are available on reasonable request from the corresponding author.