Src family kinases regulate p38 MAPK-mediated IL-6 production in Kupffer cells following hypoxia.
Tissue hypoxia is a common sequel of trauma-hemorrhage but can occur even without blood loss under hypoxic conditions. Although hypoxia is known to upregulate Kupffer cells (KC) to release cytokines, the precise mechanism of release remains unknown. We hypothesized that Src family kinases play a role in mediating KC mitogen-activated protein kinase (MAPK) signaling and their cytokine production after hypoxia. Male C3H/HeN mice received either Src inhibitor PP1 (1.5 mg/kg body wt) or vehicle 1 h before hypoxia. KCs were isolated 1 h after hypoxia, lysed, and immunoblotted with antibodies to Src, p38, ERK1/2, or JNK proteins. In addition, KCs were cultured to measure interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) production. Hypoxia produced a significant increase in KC Src and MAPK (p38, ERK, JNK) activity compared with normoxic controls. This was associated with an increase in IL-6 and MCP-1 production. Treatment with PP1 abolished the increase in KC Src activation as well as p38 activity. However, PP1 did not prevent the increase in KC ERK1/2 or JNK phosphorylation. Furthermore, administration of PP1 prevented the hypoxia-induced increase in IL-6 but not MCP-1 release by KC. Additional in vitro results suggest that p38 but not ERK1/2 or JNK are critical for KC IL-6 production. In contrast, the production of MCP-1 by KC was found to be independent of MAPK. Thus hypoxia increases KC IL-6 production by p38 MAPK activation via Src-dependent pathway. Src kinases may therefore be a novel therapeutic target for preventing immune dysfunction following low-flow conditions in trauma patients.
Center for Surgical Research, The University of Alabama at Birmingham, Volker Hall G094, 1670 University Boulevard, Birmingham, AL 35294-0019, USA.
Björn M
BM
Thobe
Michael
M
Frink
Mashkoor A
MA
Choudhry
Martin G
MG
Schwacha
Kirby I
KI
Bland
Irshad H
IH
Chaudry
D000818:Animals; D002469:Cell Separation / Q000379:methods; D018932:Chemokine CCL2 / Q000378:metabolism; D004195:Disease Models, Animal; D000860:Hypoxia / Q000276:immunology*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000276:immunology; D007728:Kupffer Cells / Q000187:drug effects / Q000276:immunology*; D020935:MAP Kinase Signaling System; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D010766:Phosphorylation; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; C412373:AG 1879; D018932:Chemokine CCL2; D015850:Interleukin-6; D011720:Pyrazoles; D011743:Pyrimidines; D019061:src-Family Kinases; D048051:p38 Mitogen-Activated Protein Kinases