Membranous epithelial cells (M cells) of the follicle-associated epithelium in Peyer's patches have a high capacity for transcytosis of several viruses and microorganisms. Here, we report that we have successfully established a bovine intestinal epithelial cell line (BIE cells) and developed an in vitro M cell model. BIE cells have a cobblestone morphology and microvilli-like structures, and strongly express cell-to-cell junctional proteins and cytokeratin, which is a specific intermediate filament protein of epithelial cells. After co-culture with murine intestinal lymphocytes or treatment with supernatant from bovine PBMC cultured with IL-2, BIE cells acquired the ability of transcytosis. Therefore, BIE cells have typical characteristics of bovine intestinal epithelial cells and also have the ability to differentiate into an M cell like linage. In addition, our results indicate that contact between immune cells and epithelial cells may not be absolutely required for the differentiation of M cells. We think that BIE cells will be useful for studying the transport mechanisms of various pathogens and also the evaluation of drug delivery via M cells.

Heat stress affects endocrine systems in cows. This study investigated changes in insulin and glucagon secretion between thermoneutral (TN; 18 degrees C, relative humidity [RH] 60%) and hot (28 degrees C, RH 60%) environments in lactating cows. Glucose, arginine, and butyrate were administered i.v. to four cows (mean, at 83 d postpartum) in each environment. Blood was collected via a jugular catheter at regular intervals. Heat exposure resulted in a marked increase in respiration rate and rectal temperature. A decrease in milk yield was also observed during heat exposure. Basal insulin concentrations were elevated, and basal glucose concentrations tended to be lower in the hot environment. Peak values of insulin and glucagon following the arginine injection were significantly higher in the hot than in the TN environment. The insulin peak value in response to the butyrate infusion was also higher during the heat exposure. However, insulin and glucagon responses to the glucose load were not affected by heat stress. The increase in plasma glucose concentration following arginine injection was inhibited by the heat exposure. In conclusion, heat stress resulted in a higher insulin secretion in lactating cows. Glucagon secretion in response to the arginine injection was enhanced, but the rise in plasma glucose was inhibited by heat exposure. These changes would be related to a reduction in milk yield during heat stress.

Rose, M. T., Aso, H., Yonekura, S., Komatsu, T., Hagino, A., Ozutsumi, K., Obara, Y. (2002). In vitro differentiation of a cloned bovine mammary epithelial cell.? Journal of Dairy Research, 69, (3), 345-355The aim of the study was to establish in vitro a bovine mammary epithelial cell (MEC) clone, able to respond to mitogenic growth factors and to lactogenic hormones. Mammary tissue from a 200-d pregnant Holstein cow was used as a source of MEC, from which a clone was established through a process of limiting dilution. When plated on plastic, the cells assumed a monolayer, cobblestone, epithelial-like morphology, with close contact between cells. Inclusion of IGF-1 and EGF in the media significantly increased the number of cells 5 d after plating. All cells stained strongly for cytokeratin and moderately for vimentin at young and old passage stages, indicating the epithelial nature of this cell clone. When the cells were plated at a high density on a thin layer of a commercial extracellular matrix preparation (Matrigel), lobular, alveoli-like structures developed within approximately 5 d, with a clearly visible lumen. When cells were plated onto Matrigel in differentiation media (containing lactogenic hormones), detectable quantities of ?-casein were present in the media and particularly on the lumen side of the structures. Omission of one of the lactogenic hormones (insulin, prolactin or hydrocortisone) reduced ?-casein release to the limit of detection of the assay used. Lactoferrin was also produced when the cells were plated on Matrigel, again principally on the lumen side of the lobules, though this was independent of the lactogenic hormones. By passage 40, the cells had senesced, and it was not possible to induce ?-casein or lactoferrin production. This study notes the establishment of a functional bovine mammary epithelial cell clone, which is responsive to mitogenic and lactogenic hormones and an extracellular matrix.Peer reviewe