Microbic Phagocytosis by Enteric Epithelial Cells

Reimann, Hobart A.

doi:10.1001/jama.1965.03080260018005

Cited by 26 publications

(26 citation statements)

References 3 publications

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“…4B). These TEM structural changes have also been reported by others (4,7,10,16). In addition, we observed a strange fine structure at the attachment area of SFB; a plasma membranelike structure of SFB that was unlacing from the holdfast segment and was connected with the host mitochondria (small arrows in Fig.…”

supporting

confidence: 89%

“…The structure of the present extracellular particle as observed by TEM resembled the intrasegmental bodies in Fig. 3A through C and those of floating SFB reported elsewhere (4,7,8,16). We failed to find these extracellular particles in seven chicks colonized with no and few SFB, whereas in six birds with high levels of SFB, extracellular particles were frequently found.…”

supporting

confidence: 84%

“…Furthermore, SFB in chickens, rats, and mice are reported to be host specific (1,24). SFB adhere to intestinal epithelial cells with holdfasts, and filaments are usually found only at the ileal villus tip of young animals (4,6,10,12,16,17). Recently, SFB have been reported to have a potential antagonistic effect against gastrointestinal infections (8).…”

mentioning

confidence: 99%

“…Although SFB are host specific (1, 24), there are at present no indications that host responses to SFB are different in mice or chickens. Attachment of SFB was recognized by a distorted cell membrane and a thickened and more electrondense underlying area of the host cell (4,7,12,16,27), which has later been identified as an accumulation of actin filaments at the attachment site (9). These morphological changes indicate a definite host reaction and imply a cell-metabolic response.…”

mentioning

confidence: 99%

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Transmission Electron Microscopic Demonstration of Phagocytosis and Intracellular Processing of Segmented Filamentous Bacteria by Intestinal Epithelial Cells of the Chick Ileum

Yamauchi

Snel

2000

Infect Immun

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Segmented filamentous bacteria (SFB) are autochthonous bacteria colonizing the ileum of many young animals by attaching to intestinal epithelial cells. These nonpathogenic bacteria strongly stimulate the mucosal immune system and induce intestinal epithelial cells to express major histocompatibility complex class II molecules. We tried to discover whether SFB are phagocytized and intracellularly processed by the host cells, which is indicative of antigen processing. The middle part of the ileum was extracted from 10-and 20-day-old broiler chicks (Gallus gallus domesticus). Samples were processed and examined by scanning and transmission electron microscopy (SEM and TEM, respectively). In SEM, no, few, medium, and dense SFB colonization levels were classified. In TEM of cells from animals with medium or dense SFB colonization levels, we could observe extracellular particles ranging from those only indenting the cell membrane to particles found in the cytoplasmatic area beyond the terminal web. These particles had a structural similarity with SFB that were floating freely in the intestinal lumen. Furthermore, we observed unlacing of the membrane and septum surrounding the extracellular particles and their incorporation into host cytoplasmatic components, which strongly suggests that these particles are phagocytized and intracellularly processed SFB. This conclusion is supported by TEM analysis of samples with no or few SFB, in which we failed to find these characteristic morphologies. The phagocytosis process described here could be an important trigger for the stimulating effect of SFB on the mucosal immune system.Segmented filamentous bacteria (SFB) are known to be nonpathogenic, gram-positive, anaerobic, spore-forming bacteria that inhabit the intestinal tract. SFB are characterized by their long filamentous shape with defined septa between each segment and their attachment to epithelial cells. Although SFB have been reported in many animal species, an official taxonomic name has not been established as yet due to the lack of an in vitro culturing method. Using 16S ribosomal DNA analysis, the phylogenetic positions of SFB in mice, rats, and chickens have been reported as being closely related to each other and distantly related to members of the genus Clostridium (19). However, SFB of chickens are different from those of mice, because SFB of mice are longer, wider, and have slightly different morphological characteristics than those of chickens (1). Furthermore, SFB in chickens, rats, and mice are reported to be host specific (1,24). SFB adhere to intestinal epithelial cells with holdfasts, and filaments are usually found only at the ileal villus tip of young animals (4,6,10,12,16,17). Recently, SFB have been reported to have a potential antagonistic effect against gastrointestinal infections (8). Observations by transmission electron microscopy (TEM) have revealed that the host cells to which SFB are anchored do not show any cytopathologic changes, and no inflammatory reactions have been observed in the lamina...

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supporting

confidence: 89%

supporting

confidence: 84%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Transmission Electron Microscopic Demonstration of Phagocytosis and Intracellular Processing of Segmented Filamentous Bacteria by Intestinal Epithelial Cells of the Chick Ileum

Yamauchi

Snel

2000

Infect Immun

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“…As the intestinal lumen was washed thoroughly before isolating the epithelial cells, any bacteria remaining in the preparations must be those closely associated with the brush border (33)(34)(35) . Animals were not routinely starved before experiments to reduce the bacterial count (5) as starvation is known to cause changes in metabolism .…”

Section: Bacteriological Studymentioning

confidence: 99%

Studies on Epithelial Cells Isolated From Guinea Pig Small Intestine

Evans

Wrigglesworth

Burdett

et al. 1971

The Journal of Cell Biology

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Sheets of mucosal epithelial cells were released from guinea pig small intestine after incubation with ethylenediaminetetraacetate . Cells in sheets retained their columnar shape for 24 hr at room temperature, and exclusion of nigrosine suggested they had intact plasma membranes . When sheets were disaggregated individual cells had normal morphology for at least 4 hr. During isolation 16% of the total protein and 24% of the total lactic dehydrogenase were lost from the cells, but subsequent enzyme leakage was low . Leakage increased with shaking, incubation at 37°C, or increasing the oxygen tension of the suspending medium, but was minimal when the Na+ : K+ ratio in the medium was 8 :1 and the osmolarity was high . Losses of particulate enzyme activities were negligible . Respiration was constant for up to 4 hr and was insensitive to calcium, bicarbonate, oxygen tension, and pH . It was inhibited by cyanide and iodoacetate and varied with the Na+ : K+ ratio of the extracellular fluid and the structural integrity of the cells . All preparations concentrated potassium and excluded sodium, but lost this ability if ouabain was added or cells were broken . Potassium-42 uptake was also sensitive to temperature, ouabain, and structural integrity. The preparations are being used to study cell metabolism in the intestinal epithelium.

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