High Glucose-Induced Expression of Proinflammatory Cytokine and Chemokine Genes in Monocytic Cells
Monocyte activation and adhesion to the endothelium play important roles in inflammatory and cardiovascular diseases. These processes are further aggravated by hyperglycemia, leading to cardiovascular complications in diabetes. We have previously shown that high glucose (HG) treatment activates monocytes and induces the expression of tumor necrosis factor (TNF)-α via oxidant stress and nuclear factor-kB transcription factor. To determine the effects of HG on the expression of other inflammatory genes, in the present study, HG-induced gene profiling was performed in THP-1 monocytes using cytokine gene arrays containing 375 known genes. HG treatment upregulated the expression of 41 genes and downregulated 15 genes that included chemokines, cytokines, chemokines receptors, adhesion molecules, and integrins. RT-PCR analysis further confirmed that HG significantly increased the expression of monocyte chemoattractant protein-1 (MCP-1), TNF-α, β2-integrin, interleukin-1β, and others. HG treatment increased transcription of the MCP-1 gene, MCP-1 protein levels, and adhesion of THP-1 cells to endothelial cells. HG-induced MCP-1 mRNA expression and monocyte adhesion were blocked by specific inhibitors of oxidant stress, protein kinase C, ERK1/2, and p38 mitogen-activated protein kinases. These results show for the first time that multiple inflammatory cytokines and chemokines relevant to the pathogenesis of diabetes complications are induced by HG via key signaling pathways.
Address correspondence and reprint requests to Rama Natarajan, Department of Diabetes, Beckman Research Institute of the City of Hope, 1500 East Duarte Rd., Duarte, CA 91010. E-mail:.
Received for publication 31 October 2002 and accepted in revised form 14 February 2003.
M.G. is currently employed by the Scripps Research Institute (La Jolla, CA).
ELISA, enzyme-linked immunosorbent assay; HAEC, human aortic endothelial cell; HG, high glucose; IFN-γ, interferon-γ; IL, interleukin; IP-10, inducible protein-10; MAPK, mitogen-activated protein kinase; MCP-1, monocyte chemoattractant protein-1; MN, mannitol; NAC, N-acetylcysteine; NF, nuclear factor; NG, normal glucose; PDTC, pyrrolidine dithiocarbamate; PKC, protein kinase C; TNF, tumor necrosis factor; TTFA, thenoyltrifluoroacetone.