title: Glucose regulates interleukin-8 production in aortic endothelial cells through activation of the p38 mitogen-activated protein kinase pathway in diabetes.
abstract: 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.
authors.affiliation: Department of Diabetes, Beckman Research Institute, City of Hope National Medical Center, Duarte, California, USA.
authors.forename: Suseela
authors.initials: S
authors.lastname: Srinivasan
authors.forename: David T
authors.initials: DT
authors.lastname: Bolick
authors.forename: Melissa E
authors.initials: ME
authors.lastname: Hatley
authors.forename: Rama
authors.initials: R
authors.lastname: Natarajan
authors.forename: Kelly B
authors.initials: KB
authors.lastname: Reilly
authors.forename: Michael
authors.initials: M
authors.lastname: Yeh
authors.forename: Carol
authors.initials: C
authors.lastname: Chrestensen
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Sturgill
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Hedrick
mesh_terms: 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
chemical_list: D017931:DNA Primers; D016209:Interleukin-8; D012333:RNA, Messenger; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D005947:Glucose