Modulation of interleukin-6 in cardiac myoblasts during endotoxemia.
BACKGROUND
Interleukin (IL)-6 is induced in the heart during endotoxemia. We investigated endotoxin-induced IL-6 in vitro and its modulation by IL-1beta and tumor necrosis factor (TNF)-alpha. Whether lipopolysaccharide (LPS) would stimulate nuclear factor (NF)-kappaB intranuclear translocation was also examined. We hypothesized that IL-6 production is enhanced with LPS and cytokine challenge and that LPS stimulates NF-kappaB intranuclear translocation in a myogenic cell line.


METHODS
Rat H9c2 cardiac myoblasts were grown in culture. IL-6 protein was determined by enzyme-linked immunosorbent assay after LPS (10 microg/ml) and in the presence of TNF-alpha or IL-1beta. IL-6 mRNA was amplified using reverse-transcription polymerase chain reaction. Myoblasts were treated with LPS and stained for the p65 subunit of NF-kappaB.


RESULTS
LPS stimulated IL-6 protein and mRNA expression (P < 0.05). IL-1beta increased IL-6 when combined with TNF-alpha (P < 0.05). In the presence of LPS, TNF-alpha lowered IL-6 production, which was further reduced upon addition of IL-1beta. LPS activated NF-kappaB showing p65 subunit cellular localization within 30 min.


CONCLUSIONS
In cardiac myoblasts, IL-6 is either enhanced or reduced depending on interactions between LPS and cytokine challenge. Enhanced nuclear translocation of NF-kappaB in response to LPS was evident in a myogenic cell line.
Vona-Davis
Linda
L
Department of Surgery, West Virginia University Morgantown, West Virginia 26506, USA.
Zhu
Xiaocheng
X
Yu
Alice K
AK
McFadden
David W
DW
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002460:Cell Line; D019446:Endotoxemia / Q000276:immunology* / Q000378:metabolism*; D015870:Gene Expression / Q000276:immunology; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D032386:Myoblasts, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000970:Antineoplastic Agents; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha