Polymeric immunoglobulin receptor (pIgR) (pIgR)

The Polymeric immunoglobulin receptor (pIgR) is the primary molecular mediator of intestinal IgA secretion, a critical process for mucosal immunity [1, 2]. It is a type I transmembrane protein expressed on the basolateral surface of epithelial cells that binds dimeric IgA and transports it to the apical surface for release into the lumen as secretory IgA (SIgA) [3, 4]. This secretion is essential for neutralizing enteric pathogens and maintaining homeostatic interactions with the gut microbiota [5, 6]. In clinical contexts, pIgR is a target for therapeutic modulation; for instance, probiotics and certain dietary metabolites are used to enhance its expression and boost mucosal defense [7, 14, 16]. Conversely, pIgR is overexpressed in several cancers, including hepatocellular carcinoma, where it serves as a biomarker and a target for inhibitory antibodies [17, 19]. Furthermore, the pIgR transcytosis pathway is being actively exploited as a platform for the targeted delivery of therapeutic biologics to mucosal surfaces [20, 24].

Other names

PIGRPoly-Ig receptorSecretory component precursorHepatocellular carcinoma-associated antigen 100Intestinal IgA secretion

pIgR mediates the transcytosis of dimeric IgA and pentameric IgM from the basolateral to the apical surface of epithelial cells [1, 2]. It binds the J chain of these immunoglobulins, undergoes endocytosis, and is subsequently cleaved at the apical membrane to release secretory IgA (SIgA) or IgM into the mucosal lumen [31].