Glucose Regulates Interleukin-8 Production in Aortic Endothelial Cells through Activation of the p38 Mitogen-activated Protein Kinase Pathway in Diabetes

• Published in: The Journal of biological chemistry Vol. 279; no. 30; pp. 31930 - 31936
• Main Authors: Srinivasan, Suseela, Bolick, David T, Hatley, Melissa E, Natarajan, Rama, Reilly, Kelly B, Yeh, Michael, Chrestensen, Carol, Sturgill, Thomas W, Hedrick, Catherine C
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 23.07.2004
• Subjects: Animals; Base Sequence; Cell Adhesion - drug effects; Cells, Cultured; Diabetes Mellitus, Type 2 - enzymology; Diabetes Mellitus, Type 2 - genetics; Diabetes Mellitus, Type 2 - immunology; DNA Primers - genetics; Endothelium, Vascular - drug effects; Endothelium, Vascular - enzymology; Endothelium, Vascular - immunology; Glucose - pharmacology; Humans; In Vitro Techniques; Interleukin-8 - biosynthesis; Interleukin-8 - genetics; Male; MAP Kinase Signaling System - drug effects; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Mitogen-Activated Protein Kinases - metabolism; Models, Biological; Monocytes - drug effects; Monocytes - physiology; p38 Mitogen-Activated Protein Kinases; RNA, Messenger - biosynthesis; RNA, Messenger - genetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M400753200

We have shown that chronic elevated glucose (25 m m ) 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 m m glucose had a 2-fold increase in p38 phosphorylation compared with control normal glucose-cultured EC. Inhibition of the p38 pathway using 5 μ m 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.