Glucose regulates monocyte adhesion through endothelial production of interleukin-8.
We have shown that glucose increases monocyte adhesion to human aortic endothelial cells (HAECs) in vitro.1 In the present study, we examined mechanisms by which glucose stimulates monocyte:endothelial interactions. HAECs cultured for 7 days in 25 mmol/L glucose had a 2-fold elevation in interleukin-8 (IL-8) secretion over control cells cultured in 5.5 mmol/L glucose (P<0.001). Use of a neutralizing antibody to IL-8 prevented glucose-mediated monocyte adhesion. Both glucose and IL-8 activated beta1 integrin on the HAEC surface, suggesting that both activate the alpha5beta1 integrin complex on the endothelial surface. The alpha5beta1 integrin complex is important for anchoring connecting segment-1 fibronectin on the HAEC surface for monocyte adhesion. Analysis of the human IL-8 promoter revealed binding sites for NF-kappaB and AP-1 as well as several aligned carbohydrate response elements (also known as E-boxes). Glucose dramatically stimulated IL-8 promoter activity. Using mutated IL-8 promoter constructs and EMSA, we found that the AP-1 element and the glucose-response element were responsible for much of the glucose-mediated activation of IL-8 transcription. Interestingly, inhibition of reactive oxygen species (ROS) production through use of pharmacological uncouplers of the mitochondrial electron transport chain significantly reduced glucose-mediated induction of IL-8 expression. These data indicate that glucose regulates monocyte:endothelial interactions through stimulation of IL-8 and ROS production and activation of the alpha5beta1 integrin complex on HAECs.
Srinivasan
Suseela
S
Division of Cardiology, University of California Los Angeles, Los Angeles, Calif, USA.
Yeh
Michael
M
Danziger
Eric C
EC
Hatley
Melissa E
ME
Riggan
Anna E
AE
Leitinger
Norbert
N
Berliner
Judith A
JA
Hedrick
Catherine C
CC
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000187:drug effects*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013804:Thenoyltrifluoroacetone / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014475:Uncoupling Agents / Q000494:pharmacology
D016209:Interleukin-8; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D014475:Uncoupling Agents; D013804:Thenoyltrifluoroacetone; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D005947:Glucose