Bacterial endotoxin stimulates macrophages to release HMGB1 partly through CD14- and TNF-dependent mechanisms.
Bacterial endotoxin [lipopolysaccharide (LPS)] stimulates macrophages to sequentially release early [tumor necrosis factor (TNF)] and late [high mobility group box 1 (HMGB1)] proinflammatory cytokines. The requirement of CD14 and mitogen-activated protein kinases [MAPK; e.g., p38 and extracellular signal-regulated kinase (ERK)1/2] for endotoxin-induced TNF production has been demonstrated previously, but little is known about their involvement in endotoxin-mediated HMGB1 release. Here, we demonstrated that genetic disruption of CD14 expression abrogated LPS-induced TNF production but only partially attenuated LPS-induced HMGB1 release in cultures of primary murine peritoneal macrophages. Pharmacological suppression of p38 or ERK1/2 MAPK with specific inhibitors (SB203580, SB202190, U0126, or PD98059) significantly attenuated LPS-induced TNF production but failed to inhibit LPS-induced HMGB1 release. Consistently, an endogenous, immunosuppressive molecule, spermine, failed to inhibit LPS-induced activation of p38 MAPK and yet, still significantly attenuated LPS-mediated HMGB1 release. Direct suppression of TNF activity with neutralizing antibodies or genetic disruption of TNF expression partially attenuated HMGB1 release from macrophages induced by LPS at lower concentrations (e.g., 10 ng/ml). Taken together, these data suggest that LPS stimulates macrophages to release HMGB1 partly through CD14- and TNF-dependent mechanisms.
Department of Emergency Medicine, North Shore University Hospital, New York University School of Medicine, 350 Community Drive, Manhasset, NY 11030, USA.
Guoqian
G
Chen
Jianhua
J
Li
Mahendar
M
Ochani
Beatriz
B
Rendon-Mitchell
Xiaoling
X
Qiang
Seenu
S
Susarla
Luis
L
Ulloa
Huan
H
Yang
Saijun
S
Fan
Sanna M
SM
Goyert
Ping
P
Wang
Kevin J
KJ
Tracey
Andrew E
AE
Sama
Haichao
H
Wang
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D019446:Endotoxemia / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D024243:HMGB1 Protein / Q000378:metabolism*; D007166:Immunosuppressive Agents / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D013096:Spermine / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D000906:Antibodies; D004791:Enzyme Inhibitors; D024243:HMGB1 Protein; D007166:Immunosuppressive Agents; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D013096:Spermine; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases