Effect of endotoxin on interleukin-6 secretion and messenger ribonucleic acid in porcine anterior pituitary cells.
The pleiotropic cytokine interleukin-6 (IL-6) is produced in and secreted from anterior pituitary (AP) cells of a number of species. Bacterial endotoxin (END) may enhance the transcription of IL-6 and its secretion from the AP. In the studies presented here, we evaluated pig AP cells for the presence of IL-6 mRNA. In addition, because we had observed previously that END stimulated the secretion of prostaglandin E2 from cultured porcine AP cells, the effects of the inhibition of END-stimulated cyclooxygenase products on IL-6 mRNA abundance and the secretion of IL-6 were evaluated. In the first experiment, RNA was extracted from cultured pig AP cells that had been treated with END for 0.5 or 1 hr and subjected to reverse transcription followed by polymerase chain reaction and hybridization after Southern transfer. Bands of expected amplified product size, corresponding to IL-6, were observed only from cells treated with END, although specific hybridization was observed from both control and END-treated wells. In the next experiment, RNA was extracted from cultured AP cells treated with END or END in the presence of the cyclooxygenase inhibitor indomethacin (IND). Amplification of the expected product could be observed from all cultured cells except those treated with IND. However, hybridization data indicated that IND did not eliminate IL-6 mRNA entirely. Next, we measured IL-6 secretion from cultured AP cells exposed to END or END and IND. Treatment with END stimulated IL-6 secretion (P < 0.001) above controls, whereas IND blocked END stimulation of IL-6 secretion (P < 0.001). Finally, using immunostaining, we confirmed the presence of CD14, an END receptor, in cultured pig AP cells. These studies clearly establish the presence of IL-6 mRNA and secretion of the cytokine from cultured porcine AP cells. In addition, END stimulates the secretion of IL-6, perhaps through cells expressing CD14, and END-stimulated IL-6 secretion appears to be mediated by products of the cyclooxygenase pathway.
Abraham
E J
EJ
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201, USA.
Oberst
R D
RD
Hays
M P
MP
Chapes
S K
SK
Minton
J E
JE
D000818:Animals; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004731:Endotoxins / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism*; D018950:Lipopolysaccharide Receptors / Q000032:analysis; D010903:Pituitary Gland, Anterior / Q000276:immunology / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D013552:Swine
D016861:Cyclooxygenase Inhibitors; D004731:Endotoxins; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D012333:RNA, Messenger; D011451:Prostaglandin-Endoperoxide Synthases; D007213:Indomethacin