Human marrow stromal cells: response to interleukin-6 (IL-6) and control of IL-6 expression.
Production of interleukin-6 (IL-6) by marrow stromal cells from human long-term marrow cultures and from stromal cells transformed with simian virus 40 was examined. As with other cultured mesenchymal cells, unstimulated stromal cells produced undetectable amounts of IL-6 mRNA when assayed by Northern blots. However, within 30 minutes after exposure of transformed marrow stromal cells to the inflammatory mediators, recombinant human interleukin-1 alpha (IL-1 alpha) or recombinant human tumor necrosis factor alpha (TNF alpha), significant increases in IL-6 expression were observed. The time course of IL-6 mRNA upregulation in transformed marrow stromal cells with IL-1 alpha and TNF alpha differed: The maximal response to TNF alpha was observed at 30 minutes whereas that to IL-1 alpha occurred at 8 hours. Although IL-6 at a concentration of 500 U/mL was inhibitory to adherent transformed marrow stromal cell proliferation, a concentration-dependent stimulation of anchorage-independent colony growth was observed when the cells were plated in semisolid medium with IL-6. The stromal cell colony-stimulating effect of IL-6 was abrogated by a neutralizing antibody to IL-6. Moreover, the heteroserum with anti-IL-6 activity and two anti-IL-6 monoclonal antibodies partially blocked autonomous and IL-1 alpha-induced colony formation, suggesting that colony formation by transformed marrow stromal cells may require IL-6. Clonal-transformed stromal cell lines were derived from the anchorage-independent stromal cell colonies. Both IL-6 mRNA and protein were constitutively produced at high levels. The addition of IL-6 to either long-term marrow culture adherent cells or transformed marrow stromal cells downregulated the expression of collagen I, a major stromal cell matrix protein. Thus, IL-6 affects proliferation of stromal cells and influences their production of extracellular matrix, suggesting that IL-6 may have indirect as well as direct influences on hematopoietic cell proliferation.
Nemunaitis
J
J
Medical Service, Veterans Administration Medical Center, Seattle, WA 98108.
Andrews
D F
DF
Mochizuki
D Y
DY
Lilly
M B
MB
Singer
J W
JW
D015152:Blotting, Northern; D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007375:Interleukin-1; D015850:Interleukin-6; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha