Determining the importance of fecal biomarkers (human S100 calcium binding protein, Calprotectin, Lysozyme) in diagnosis and follow up of allergic proctocolitis

Aim Food protein induced allergic proctocolitis (FPIAP) is a non-IgE-mediated allergic disorder of infancy, characterized by blood-streaked stools. The diagnosis of FPIAP relies on elimination and provocation tests. We aimed to unveil potential non-invasive biomarkers for diagnosis and follow up of FPIAP patients. Materials and Method In our prospective, multi-center study we enrolled 49 infants aged 1 to 12 months that were diagnosed with FPIAP according to the ESPGHAN guidelines and 50 age and gender matched healthy controls. We measured fecal levels of Lysozyme, Calgranulin-C (S100A12) and Calprotectin with ELISA method during active disease and after elimination diet and compared them to the control group. Patient histories and physical examinations were documented and evaluated for significance. Results Levels of Calgranulin-C in FPIAP patients were significantly higher than the control group (p<0,001). In contrast, fecal lysozyme levels during active disease were lower than of the control group (p<0,001). The presence of bloody stool correlated with higher levels of Calgranulin among the FPIAP group at the time of admission and following remission (p=0,045 and p=0,038). Within the FPIAP group, all three biomarkers showed statistically significant differences before elimination diet and after subsequent remission. Conclusions Levels of fecal Calgranulin and Lysozyme show potential in diagnosing FPIAP, whereas all three biomarkers could be used in monitoring response to therapy. Future prospective studies are needed to further validate our findings. Keywords: Calgranulin-C, Calprotectin, FPIAP, Lysozyme, S100A12