Atorvastatin inhibition of cytokine‐inducible nitric oxide synthase expression in native endothelial cells in situ

Abstract

1 Animal experimental studies have demonstrated that inducible nitric oxide synthase (iNOS) expression correlates with neointima formation and is prevented by HMG-CoA reductase inhibitors (statins). In the present study we have investigated the underlying mechanism of action of these drugs in isolated segments of the rat aorta. 2 Western blot analysis and immunohistochemistry revealed that tumour necrosis factor a (TNFa) plus interferon-g (IFNg) synergistically induce iNOS gene expression in the endothelium but not in the smooth muscle of these segments while constitutive endothelial NO synthase (eNOS) abundance was markedly reduced. 3 Pre-treatment with 1 ± 10 mM atorvastatin, cerivastatin or pravastatin decreased TNFa plus IFNg stimulated iNOS expression in the endothelium irrespective of the presence of the HMG-CoA reductase product mevalonate (400 mM). 4 Electrophoretic mobility shift assay experiments con®rmed that the combination of TNFa plus IFNg causes activation of the transcription factors STAT-1 and NF-kB in native endothelial cells. Neutralization of these transcription factors by employing the corresponding decoy oligonucleotides con®rmed their involvement in TNFa plus IFNg stimulated iNOS expression. Translocation of both transcription factors was attenuated by atorvastatin, and this eect was insensitive to exogenous mevalonate. 5 The present ®ndings thus demonstrate a speci®c HMG-CoA reductase-independent inhibitory eect of statins, namely atorvastatin, on cytokine-stimulated transcription factor activation in native endothelial cells in situ and the subsequent expression of a gene product implicated in vascular in¯ammation. This eect may be therapeutically relevant and in addition provide an explanation for the reported rapid onset of action of these drugs in humans.

Chronic mevastatin modulates receptor-dependent vascular contraction in eNOS-deficient mice

“…Besides lowering elevated plasma cholesterol levels, statins are now known to confer several other benefits for cardiovascular function, including stabilization of atherosclerotic plaques (36), limiting cerebral infarct size (1,9,22), and reducing oxidative stress (8,38). Thus far, such beneficial effects of statins have been thought to be solely due to their ability to increase eNOS expression and activity and hence increase NO bioavailability in the vasculature (14,18,23).…”

Interleukin-10 Induction of Nitric-oxide Synthase Expression Attenuates CD40-mediated Interleukin-12 Synthesis in Human Endothelial Cells

“…Nitrite Determination-Nitrite was measured as an estimate of NO production by a modified Griess reaction (16). To obtain IL-10 effects independent from vitamin D3, the cultured endothelial cells were preincubated with a combination of cytokines (60 units/ml IL-1␤, 1000 units/ml TNF-␣, and 1000 units/ml IFN␥) for 12 h to induce IL-10R expression.…”

“…After this time, the cells were washed twice with culture medium and then exposed to IL-10 (2 ng/ml) and/or to the same combination of cytokines as described before. Cell culture supernatants were collected 48 h post-cytokine exposure and assayed for their nitrite content as described previously (16).…”

Statins as antiinflammatory and immunomodulatory agents: A future in rheumatologic therapy?

“…Lovastatin, atorvastatin, and fluvastatin decrease both LPS-and interferon-␥ (IFN␥)-stimulated iNOS expression in murine macrophages by reducing iNOS transcription, an effect that is reversed by mevalonate, GGPP, or FPP (75). Atorvastatin, cerivastatin, and pravastatin all decrease TNF␣/IFN␥-stimulated iNOS expression in mouse aortic endothelium (76).…”