Clinical investigation of intestinal fatty acid-binding protein (I-FABP) as a biomarker of SARS-CoV-2 infection

Objectives: SARS-CoV-2 exhibits tropism for the gastrointestinal tract; however, lesions in enterocytes and their correlation with disease severity and patient prognosis are still unknown. Methods: SARS-CoV-2 patients were enrolled in 5 medical centres in Sao Paulo, Brazil and their clinical characteristics and laboratory findings recorded. At admission, day 7 and day 14 of hospitalisation, plasma and urine samples were collected, and cytokine levels and intestinal fatty acid-binding protein (I-FABP) concentrations measured. Results: COVID-19 patients displayed approximate to 48-, 74-and 125-fold increased urinary I-FABP levels at admis-sion ( n = 283; P < 0.001), day 7 ( n = 142; P < 0.01) and day 14 ( n = 75; P < 0.01) of hospitalisation. Critically ill patients and nonsurvivors showed higher I-FABP concentrations compared with patients with less severe illness. At admission, infected patients demonstrated enhanced production of plasma interferon (IFN)-gamma and interleukin (IL)-6. The receiver operating characteristic curve suggested I-FABP as a biomarker for COVID-19 disease severity at admission ( P < 0.0 0 01; Youden index = 6.89; area under the curve = 0.699). Patients with I-FABP >= 6.89 showed higher IL-6 and C-reactive protein levels ( P < 0.001) at admission and had a prolonged length of hospital stay. Conclusions: Our findings revealed damage to enterocytes in SARS-CoV-2 infection, which is associated with illness severity, poor prognosis and exacerbated inflammatory response. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. (AU)