Food Protein-Induced Allergic Proctocolitis (FPIAP): New Insights into Pathogenesis and Implications

Food protein induced allergic proctocolitis (FPIAP) is one of the earliest presentations of food allergies in infancy. It is a non-immunoglobulin E (IgE)-mediated condition. Although the inflammation is located at the rectosigmoid colon, clinical symptoms are not limited to mucousy, bloody stools and often include gastroesophageal reflux (GER), feeding difficulties, irritability and poor sleep. 16S gut microbiome analyses have demonstrated that dysbiosis of the intestinal microbiota started prior to the onset of FPIAP symptoms and persisted during the active disease phase, suggesting that dysbiosis of the gut microbiome likely plays a role in the pathogenesis of FPIAP. Furthermore, infants with FPIAP have increased risk of developing IgE-mediated food allergies and eosinophilic esophagitis (EoE) later in life, indicating the possible connection between non-IgE-mediated FPIAP and IgE-mediated food allergies. Insights gained in understanding the pathogenesis of FPIAP and its association with other food allergic conditions will not only help in better managing FPIAP but also facilitate designing therapeutic strategies for preventing and treating food allergic conditions and hopefully altering the progress of atopic march.