Role of M Cells and Macrophages in the Entrance of Mycobacterium paratuberculosis into Domes of Ileal Peyer's Patches in Calves

Abstract

Ligated ileal loops of calves were inoculated with live and heat-killed Mycobacterium paratuberculosis and were examined by light and electron microscopy. At 5 hours after inoculation, acid-fast bacilli were in subepithelial macrophages, but not in M cells covering domes. At 20 hours, more than 50 acid-fast bacilli per cross section were in subepithelial macrophages in domes. Both living and heat-killed bacilli passed into domes. Addition of anti-M. paratuberculosis bovine serum to the inoculum enhanced entry of bacteria into domes. By electron microscopy, intact bacilli with electron-transparent zones (peribacillary spaces) were in the supranuclear cytoplasm of M cells at 20 hours. M cells also contained vacuoles, including electron-dense material interpreted as degraded bacilli. Subepithelial and intraepithelial macrophages contained bacilli and degraded bacterial material in phagosomes. These results suggest that calf ileal M cells take up bacilli, and that subepithelial and intraepithelial macrophages secondarily accept bacilli or bacterial debris which are expelled from M cells.

Microparticulate polyelectrolyte complexes for gentamicin transport across intestinal epithelia

“…by the different M cell proportion in FAE. These results could be attributed to the intense activity of sub-epithelial and intra-epithelial macrophages included in PP, as already observed by other authors for the transport of bacteria (Mamotani et al, 1988). On the contrary, a slight phagocytotic activity was referred for macrophages found at the lamina propria of the villus tips in some mammals (Iwanaga, 1995).…”

Experimental challenge models for Johne's disease: A review and proposed international guidelines

“…The inoculum is then injected through the rubber stopper and into the isolated ileum. The Foley catheters and rubber stoppers are left in place allowing the inoculum to be in mucosal contact for 1 h. MAP is taken up by M cells, and by dendritic and epithelial cells of the ileum and jejunum, within 30 min (Momotani et al, 1988;Sigurdardottir et al, 1999;Sigurdardottir et al, 2001). The inoculation procedure is repeated the next day.…”

“…An alternative surgical approach is the ligated intestinal loop model with an injected inoculum of 3 Â 10 9 CFU ($300 mg wet weight) (Momotani et al, 1988). This is only suitable for studies <12 h in duration and includes endpoints such as MAP detection and histopathology.…”

Bovine paratuberculosis: recent advances in vaccine development

“…M cells, specialized in uptake of particles, preferentially bind bacteria and transport them to the basolateral side (Momotani et al 1988). Following release of MAP in the extracellular fluid of the lamina propria, they are taken up by macrophages, which normally process bacteria via enzymatic processes.…”