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

Saia, Rafael Simone; Giusti, Humberto; Silva, Fábio Luís; Pedroso, Karina de Jesus Bonicenha; Auxiliadora-Martins, Maria; Morejón, Karen Mirna Loro; Degiovani, Augusto Marcussi; Cadelca, Márcia Regina; Basile-Filho, Anibal

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 five medical centres in the São Paulo State, Brazil. Clinical characteristics and laboratory findings of patients were recorded. At admission, 7th and 14th day of hospitalisation, plasma and urine samples were collected. The levels of cytokines (IFN-γ, IL-6 and TNF-α) and the biomarker intestinal fatty acid-binding protein (I-FABP) were measured. Results COVID-19 patients displayed ≈48-, 74- and 125-fold increased urinary I-FABP levels at admission (n=283; p<0.001), 7th (n=142; p<0.01) and 14th day (n=75; p<0.01) of hospitalisation, respectively. Critically ill patients and nonsurvivors showed higher I-FABP concentrations compared to those in the infirmary and survivors, respectively, within the same hospital stay periods. At admission, infected patients demonstrated enhanced production of plasma IFN-γ and IL-6. The ROC curve suggested I-FABP as a biomarker for disease severity of COVID-19 at admission (p<0.0001; Youden index=6.89; AUC=0.699). Patients with I-FABP≥6.89 showed higher IL-6 and C-reactive protein levels (p<0.001) at admission, as well as prolonged length of hospital stay. Conclusions Our findings revealed damage to enterocytes in SARS-CoV-2 infection, which is associated to illness severity, poor prognosis and exacerbated inflammatory response.