Swine Intestinal Epithelial Cells Research Articles

Apolipoprotein secretion and lipid synthesis: regulation by fatty acids in newborn swine intestinal epithelial cells.

The IPEC-1 newborn swine intestinal epithelial cell line was used to determine the effects of the uptake of various fatty acids on the secretion of apolipoprotein (apo) B and apo A-I, as well as triglyceride and phospholipid. Long-chain saturated fatty acids were taken up and stimulated triglyceride synthesis, and palmitic (16:0) and stearic (18:0) acids also stimulated phospholipid synthesis. However, these fatty acids did not enhance triglyceride, phospholipid, or apo B or apo A-I secretion. Oleic acid (18:1) was the most effective of all fatty acids tested in stimulating triglyceride synthesis and the secretion of triglyceride, phospholipid, and apo B. Linoleic (18:2) and linolenic (18:3) acids were no more effective than long-chain saturated fatty acids in stimulating these processes. With saturated fatty acids, apo A-I followed the same secretory pattern as apo B. However, among the unsaturated fatty acids, oleic acid was the least effective and linolenic acid was the most effective in stimulating apo A-I secretion. Basolateral secretion of lipid and apolipoproteins by differentiated IPEC-1 cells is differentially regulated by apical exposure to fatty acids.

Lipoprotein and apolipoprotein secretion by a newborn piglet intestinal cell line (IPEC-1).

The aim of these studies was to characterize the synthesis and secretion of lipoproteins and apolipoprotein B (apo B) and apo A-I by a newborn swine intestinal epithelial cell line (IPEC-1). Differentiated cells exhibited enterocytic features, including microvilli. [3H] oleic acid was taken up and incorporated into cellular lipids and secreted into the basolateral medium in lipoproteins. Total apo B and apo A-I secreted increased with oleic acid incubation. However, cellular apo B and apo A-I content did not change. Whereas undifferentiated cells synthesized and secreted only apo B-100, both apo B-100 and apo B-48 were produced by differentiated cells. The ratio of radiolabeled apo B-48 to apo B-100 in both basolateral medium and cell homogenate increased with oleic acid treatment after 24-h steady-state labeling. However, apo B mRNA editing was unchanged, indicating posttranslational regulation of this ratio. Pulse-chase radiolabeling demonstrated no major changes in cellular or basolateral medium apolipoprotein labeling kinetics with oleic acid or dexamethasone incubation. The dissociation of apo B and apo A-I mass secretion from the secretion of radiolabeled apo B and apo A-I in response to oleic acid absorption suggests the presence of an intracellular pool of apolipoprotein with a slow turnover that is mobilized for secretion in response to fatty acid uptake.

Tropism of human adenovirus type 5-based vectors in swine and their ability to protect against transmissible gastroenteritis coronavirus.

The infection of epithelia] swine testicle and intestinal porcine epithelial (IPEC-1) cell lines by adenovirus type 5 (Ad5) has been studied in vitro by using an Ad5-luciferase recombinant containing the firefly luciferase gene as a reporter. Porcine cell lines supported Ad5 replication, showing virus titers, kinetics of virus production, and luciferase expression levels similar to those obtained in human 293 cells, which constitutively express the 5'-end 11% of the Ad5 genome. The tropism of Ad5-based vectors in swine and its ability to induce an efficient immune response against heterologous antigens expressed by foreign genes inserted in these vectors has been determined. Ad5 vectors replicate and express heterologous antigens in porcine lungs and mediastinal and mesenteric lymph nodes. Significant levels of heterologous antigen expression were also demonstrated in the small intestine (jejunum and ileum), but Ad5 replication in this organ was very poor, suggesting that Ad vectors undergo an abortive replication in the porcine small intestine. The tissues infected by Ad5 were dependent on the inoculation route. The oronasal route appeared to be best for inoculation of bronchus-associated lymphoid tissue infection, while the intraperitoneal route was best for gut-associated lymphoid tissue infection. Epithelial cells of bronchioles, macrophages, type II pneumocytes, and follicular dendritic cells were identified as targets for Ad5, while epithelial cells of the intestine were not infected by Ad5. Viruses with a deletion from 79.5 to 84.8 map units in the E3 region, with or without heterologous inserted genes, replicated to lower levels in porcine tissues than did wild-type Ad5. It was also shown that an Ad5 recombinant expressing the four antigenic sites (A, B, C, and D) of transmissible gastroenteritis coronavirus (TGEV) spike protein induced in swine immune responses which neutralized TGEV infectivity. In addition, porcine serum from Ad-TGEV-immune animals provide passive protection when mixed with fully virulent TGEV and orally administered to highly susceptible newborn piglets. These results taken together indicate that swine may be a good animal model for human Ad5 lung infection to aid in the evaluation of candidate adenovirus vaccines and that Ad5 may be suitable as a recombinant viral vaccine or for other applications in swine.

In vitro attachment of Treponema hyodysenteriae to mammalian epithelial cells

The interaction between Treponema hyodysenteriae and isolated swine intestinal epithelial cells or mouse adrenal cells in culture was examined. Studies were performed in which treponemes were incubated with each type of anomal cell in an atmosphere of 5% CO2 in air. Coincubation was terminated at various time intervals, and the percentage of treponemal attachment evaluated by light microscopy. The extent of attachment was dependent on both incubation time and temperature. The mechanism of attachment to the animal cell surface was examined by scanning electron microscopy. Interaction of the parasite with the host cell did not appear to alter cellular morphology or result in changes of the cell surface at the site of attachment. Preference for a cellular site of attachment was not found.