The human myelomonocytic cell line U-937 as a model for studying alterations in steroid-induced monokine gene expression: marked enhancement of lipopolysaccharide-stimulated interleukin-1 beta messenger RNA levels by 1,25-dihydroxyvitamin D3.
The active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], is a potent regulator of human monocyte/macrophage function in vitro. To establish a model for 1,25-(OH)2D3 regulation of human monocyte monokine synthesis, three human cell lines (U-937, THP-1, and HL-60) were examined for: 1) the presence of functional 1,25-(OH)2D3 receptors; 2) the accumulation of interleukin-1 beta (IL-1 beta) mRNA and IL-1 beta protein in response to lipopolysaccharide (LPS); and 3) the regulation of this response by 1,25-(OH)2D3. All three cell lines expressed vitamin D receptor and had increased levels of IL-1 beta mRNA in response to LPS. Preincubation of cells with 1,25-(OH)2D3 augmented IL-1 beta mRNA levels only in U-937 and HL-60 cells. From these data, and taking into consideration their state of differentiation and relative ease of culture, U-937 was chosen over HL-60 and THP-1 as the cell line we further characterized. In U-937 cells, optimum time and dose of pretreatment with 1,25-(OH)2D3 were determined to be 12-24 h at a receptor saturating concentration of 1,25-(OH)2D3 (10 nM). Preincubation of cells with 1,25-(OH)2D3 had no effect on the time course of IL-1 beta mRNA appearance in response to LPS. However, exposure of U-937 cells to 1,25-(OH)2D3 increased by 200% the level of IL-1 beta mRNA detected and decreased by three orders of magnitude the concentration of LPS required to achieve steady state mRNA levels equivalent to those observed in U-937 cells not preincubated with the hormone.2+o
Fagan
D L
DL
Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California 90048.
Prehn
J L
JL
Adams
J S
JS
Jordan
S C
SC
D002117:Calcitriol / Q000494:pharmacology*; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007375:Interleukin-1 / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000378:metabolism*; D009000:Monocytes / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism
D007375:Interleukin-1; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D002117:Calcitriol