Transepithelial Pathogen Uptake into the Small Intestinal Lamina Propria

Abstract

The lamina propria that underlies and stabilizes the gut lining epithelium is densely populated with strategically located mononuclear phagocytes. Collectively, these lamina propria macrophages and dendritic cells (DC) are believed to be crucial for tissue homeostasis as well as the innate and adaptive host defense. Lamina propria DC were recently shown to gain direct access to the intestinal lumen by virtue of epithelium-penetrating dendrites. However, the role of these structures in pathogen uptake remains under debate. In this study, we report that entry of a noninvasive model pathogen (Aspergillus fumigatus conidia) into the murine small intestinal lamina propria persists in the absence of either transepithelial dendrites or lamina propria DC and macrophages. Our results suggest the existence of multiple pathogen entry pathways and point at the importance of villus M cells in the uptake of gut lumen Ags. Interestingly, transepithelial dendrites seem altogether absent from the small intestine of BALB/c mice suggesting that the function of lamina propria DC extensions resides in their potential selectivity for luminal Ags, rather than in general uptake or gut homeostasis.

Distinct Differentiation Potential of Blood Monocyte Subsets in the Lung

“…1E), supporting their definition as DC and M⌽, respectively (31). Interestingly, we recently reported the same CX 3 CR1 expression pattern for small intestinal lamina propria DC and M⌽ (33). CX 3 CR1 is therefore a reliable marker allowing discrimination of CD11c ϩ DC and M⌽ in the lung and alveolar space.…”

Monocytes give rise to mucosal, but not splenic, conventional dendritic cells

“…Strikingly, adoptively transferred monocytes effi ciently seeded the recipient spleen with CD11c int progenies but did not give rise to splenic CD11c high DCs. In contrast, in the same MP-depleted mice, the grafted Gr1 high monocytes effi ciently reconstituted the small intestinal lp with lpDCs and lpMΦs (27). Furthermore, grafted Gr1 high monocytes also gave rise to DCs in another nonlymphoid tissue, the lung.…”

Lectin histochemical aspects of the ovarian lamellae epithelium of Genypterus blacodes (Schneider, 1801)

“…The glycocalyx is a cellular structure with a great number of functions assigned in different epithelia. An example of these functions is the brush border of the gut absorptive cells that act as a protective layer (Vallon-Eberhard et al 2006). Reactivity to different types of lectins indicates the diversity and intricacy of the glycocalyx (Pajak & Danguy 1993).…”