Glucose regulates interleukin-8 production in aortic endothelial cells through activation of the p38 mitogen-activated protein kinase pathway in diabetes.
We have shown that chronic elevated glucose (25 mm) increases monocyte adhesion to human aortic endothelial cells (EC). This increased adhesion is mediated primarily through induction of interleukin (IL)-8 via activation of the transcription factor AP-1 (Srinivasan, S., Yeh, M., Danziger, E. C., Hatley, M. E., Riggan, A. E., Leitinger, N., Berliner, J. A., and Hedrick, C. C. (2003) Circ. Res. 92, 371-377). In the current study, we identified the elements in the AP-1 transcriptional complex that are activated by glucose. These elements include c-Jun, c-Fos, and Fra-1. AP-1 is activated by cellular oxidative stress, and we have reported significant production of ROS by high glucose-cultured cells. We examined signaling pathways upstream of AP-1 in EC that lead to AP-1 activation by HG. EC cultured in 25 mm glucose had a 2-fold increase in p38 phosphorylation compared with control normal glucose-cultured EC. Inhibition of the p38 pathway using 5 microm SB203580 significantly reduced glucose-mediated IL-8 mRNA production by 60%. Furthermore, blocking p38 pathway activation using a dominant-negative p38 construct significantly reduced glucose-mediated monocyte adhesion by 50%. Thus, glucose-stimulated monocyte adhesion is primarily regulated through phosphorylation of p38 with subsequent activation of AP-1, leading to IL-8 production. To study this pathway in the setting of diabetes, we used the db/db mouse. P38 phosphorylation was increased in diabetic db/db mice compared with control mice. We found a dramatic elevation in plasma levels of KC, the mouse ortholog of IL-8 in diabetic db/db mice (1800 +/- 100 pg/ml KC in db/db versus 300 +/- 75 pg/ml in C57BL/6J control mice, p < 0.0001). Inhibition of the p38 pathway in diabetic db/db mice significantly reduced monocyte adhesion by 50%. Taken together, these data indicate that chronic elevated glucose in diabetes activates the p38 MAP kinase pathway to increase inflammatory IL-8 gene induction and monocyte/endothelial adhesion.
Srinivasan
Suseela
S
Department of Diabetes, Beckman Research Institute, City of Hope National Medical Center, Duarte, California, USA.
Bolick
David T
DT
Hatley
Melissa E
ME
Natarajan
Rama
R
Reilly
Kelly B
KB
Yeh
Michael
M
Chrestensen
Carol
C
Sturgill
Thomas W
TW
Hedrick
Catherine C
CC
D000818:Animals; D001483:Base Sequence; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D009000:Monocytes / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases
D017931:DNA Primers; D016209:Interleukin-8; D012333:RNA, Messenger; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D005947:Glucose