The role of MAPK in Kupffer cell toll-like receptor (TLR) 2-, TLR4-, and TLR9-mediated signaling following trauma-hemorrhage.
Severe injury deranges immune function and increases the risk of sepsis and multiple organ failure. Kupffer cells play a major role in mediating posttraumatic immune responses, in part via different Toll-like receptors (TLR). Although mitogen-activated protein kinases (MAPK) are key elements in the TLR signaling pathway, it remains unclear whether the activation of different MAPK are TLR specific. Male C3H/HeN mice underwent midline laparotomy (i.e., soft tissue injury), hemorrhagic shock (MAP approximately 35 mm Hg for 90 min), and resuscitation. Kupffer cells were isolated 2 h thereafter, lysed and immunoblotted with antibodies to p38, ERK1/2, or JNK proteins. In addition, cells were preincubated with specific inhibitors of p38, ERK1/2, or JNK MAPK followed by stimulation with the TLR2 agonist, zymosan; the TLR4 agonist, LPS; or the TLR9 agonist, CpG DNA. Cytokine (TNF-alpha, interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and KC) production was determined by cytometric bead array after 24 h in culture. MAPK activity as well as TNF-alpha, MCP-1, and KC production by Kupffer cells were significantly increased following trauma-hemorrhage. TLR4 activation by LPS stimulation increased the levels of all measured cytokines. CpG-stimulated TLR9 signaling increased TNF-alpha and IL-6 levels; however, it had no effect on chemokine production. Selective MAPK inhibition demonstrated that chemokine production was mediated via p38 and JNK MAPK activation in TLR2, -4, and -9 signaling. In contrast, TNF-alpha and IL-6 production was differentially regulated by MAPK depending on the TLR pathway stimulated. Thus, Kupffer cell TLR signaling employs different MAPK pathways in eliciting cytokine and chemokine responses following trauma-hemorrhage.
Thobe
Bjoern M
BM
Center for Surgical Research and Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA.
Frink
Michael
M
Hildebrand
Frank
F
Schwacha
Martin G
MG
Hubbard
William J
WJ
Choudhry
Mashkoor A
MA
Chaudry
Irshad H
IH
D000818:Animals; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D006470:Hemorrhage / Q000473:pathology / Q000503:physiopathology*; D015850:Interleukin-6 / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology; D007728:Kupffer Cells / Q000473:pathology / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000502:physiology*; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000502:physiology*; D051217:Toll-Like Receptor 9 / Q000819:agonists / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014947:Wounds and Injuries / Q000473:pathology / Q000503:physiopathology; D015054:Zymosan / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; D015850:Interleukin-6; D008070:Lipopolysaccharides; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; C495370:Tlr9 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha; D015054:Zymosan; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases