Intestinal epithelial cells (IEC) play a central role in innate and acquired mucosal immunity. They ensure early signaling to trigger an inflammatory response against pathogens. Moreover, IEC mediate transcytosis of dimeric IgA (dIgA), through the polymeric-immunoglobulin receptor (pIgR), to provide secretory IgA, the major protective Ig in mucosal secretions. Using an in vitro model of polarized IEC, we describe an additional anti-inflammatory mechanism of dIgA-mediated protection against intracellular bacterial components involved in the proinflammatory activation of IEC. Specific dIgA colocalizes to lipopolysaccharide (LPS) in the apical recycling endosome compartment, preventing LPS-induced NF-κB translocation and subsequent proinflammatory response. Thus, intracellular neutralization by dIgA limits the acute local inflammation induced by proinflammatory pathogen-associated molecular patterns such as LPS.
Fernandez, M. I., Pedron, T., Tournebize, R., Olivo-Marin, J. C., Sansonetti, P. J., & Phalipon, A. (2003). Anti-inflammatory role for intracellular dimeric immunoglobulin A by neutralization of lipopolysaccharide in epithelial cells. Immunity, 18(6), 739–749. https://doi.org/10.1016/S1074-7613(03)00122-5