Gallus gallus bursal FAE and IFE

A minor population of M cells within the follicle-associated epithelium (FAE) of intestinal Peyer’s patches (PP) serves as a major portal for entry of exogenous antigens. Characterization of the mammalian M cells, including identification of M-cell surface molecules used for bacterial uptake, has been hampered by their relative rarity. In contrast, M cells constitute virtually all of the FAE cells in the avian bursa of Fabricius. We therefore performed comparative gene expression profiling of chicken and murine FAE to identify commonly expressed genes by M cells in both species. The comprehensive transcriptome analysis revealed that 28 genes were commonly up-regulated in FAE from both species. In situ hybridization (ISH) revealed that annexin A10 (Anxa10) mRNA was scattered in FAE, and co-localized with Ulex europaeus agglutinin-1(UEA-1) that binds to M cells. Whole-mount immunostaining also revealed that cellular prion protein (PrPC) was expressed on the luminal side of the apical plasma membrane of M cells, and co-localized with grycoprotein2 (GP2) that recognizes only M cells in murine PP. Taken together, we found new M-cell-specific molecules by using comprehensive transcriptome analysis. These molecules conserved in M cells from both species might play critical roles in M-cell function and/or differentiation. Bursa of Fabricius were dissected from the rectum and soaked in Hank's Buffered Salt Solution (HBSS) (GIBCO) containing black ink for 5 min at room temperature to visualize FAE. After incubation, the tissue was treated with 40 mM EDTA/25 mM Hepes (pH 7.4) in HBSS for 5min at room temperature to collect bursal FAE or 30 min at 37ºC for bursal IFE. Bursal FAE and IFE were collected with a fine 29G needle under stereomicroscope monitoring (n=2)