Interleukin 1 beta induces the expression of interleukin 6 in rat intestinal smooth muscle cells.
OBJECTIVE
The increased expression of several cytokines, including interleukin 6 (IL-6), has recently been reported in a study of the longitudinal muscle and myenteric plexus layers of rat intestine following Trichinella spiralis infection. However, the putative cellular sources and the mechanism underlying the induction of IL-6 in these tissues are presently unknown. The aim of this study was to examine the ability of cultured smooth muscle cells from rat jejunum to produce IL-6 messenger RNA and protein and to investigate the underlying mechanism.


METHODS
Cultured smooth muscle cells were treated with human recombinant interleukin 1 beta (HrIL-1 beta). The level of IL-6 messenger RNA was estimated by polymerase chain reaction, and the released IL-6 protein was estimated by bioassay.


RESULTS
HrIL-1 beta induced IL-6 messenger RNA expression in the smooth muscle cells in a time- and concentration-dependent manner. This was accompanied by the secretion of IL-6 protein into the medium. The effect of HrIL-1 beta was blocked by the IL-1 receptor antagonist, by actinomycin D, or by prior boiling of the cytokine.


CONCLUSIONS
These findings show that HrIL-1 beta interacts with its receptor on smooth muscle cells to induce transcription of the IL-6 gene and to cause the secretion of IL-6. These results indicate that intestinal smooth muscle cells are not only targets for but also a source of cytokine.
Khan
I
I
Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada.
Blennerhassett
M G
MG
Kataeva
G V
GV
Collins
S M
SM
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007375:Interleukin-1 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D008297:Male; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology
D007375:Interleukin-1; D015850:Interleukin-6; D012333:RNA, Messenger; D011994:Recombinant Proteins; D003609:Dactinomycin; D003513:Cycloheximide