Figure 1: PD-L1 expression is detectable in both Crohn’s disease and control ileal tissue.
From: Intestinal APCs of the endogenous nanomineral pathway fail to express PD-L1 in Crohn’s disease
(A) Schematic representation of the cellular organisation of the ileal region. The translocation of luminal antigens to APCs via the nanomineral-antigen-peptidoglycan (NAP) pathway is outlined. In brief, calcium and phosphate ions are secreted from epithelial cells back into the intestinal lumen where they mix with luminal molecules and subsequently precipitate forming nanoparticles which trap small quantities of food proteins and bacterial antigens. The resulting NAP conjugates are translocated from the lumen to the mucosa through M-cells and chaperoned APCs for uptake. Upon digestion of NAPs, peptidoglycan-induced PD-L1 is expressed on the APC surface and contributes to immune tolerance towards intestinal antigens. Typical confocal micrographs showing PD-L1 expression (red) in (B) epithelial cells and (C) ileal lymphoid patches from Crohn’s disease and control tissue sections. The ileal lymphoid patch is outlined in yellow. Scale bars are 50 μm (B) and 150 μm (C).
