[Cell adhesion. Molecular principles and initial implications for surgery]

Suppressive effect of short-interfering RNA on hyperglycemia-induced expression of intercellular adhesion molecule-1 on cultured vascular endothelial cells

PURPOSE

The pathology of diabetic retinopathy involves endothelial dysfunction, in which leukocyte adhesion to the vascular endothelium via intercellular adhesion molecule-1 (ICAM-1) may play a key role. Short-interfering RNAs (siRNAs) are unique modulators of gene expression in mammalian cells. The purpose of this study was to evaluate the enhanced effect of hyperglycemia and the attenuating effect of siRNAs on ICAM-1 expression in cultured endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVECs) were seeded onto 24-well culture plates. The following day, ICAM-1-specific siRNAs were transfected using Lipofectamine 2000. Glucose (15, 30, or 45 mM) or interleukin-1ss as a positive control was added to the medium to stimulate ICAM-1. After 48 hours, the HUVECs were collected to measure the ICAM-1 expression by enzyme-linked immunosolvent assay. Fluoresceinated siRNAs were transfected into HUVECs to confirm transfection of the siRNAs into HUVECs by fluorescein microscopy.

RESULTS

Glucose enhanced the ICAM-1 expression in a dose-dependent manner. ICAM-1 expression stimulated by hyperglycemia decreased significantly in the HUVECs transfected with corresponding siRNAs. Transfection of siRNAs was confirmed with enhanced fluorescence in HUVECs incubated with control siRNAs.

CONCLUSIONS

These results suggested that hyperglycemia stimulated protein expression of ICAM-1 and that siRNAs suppressed gene expression of ICAM-1 in HUVECs. The RNA-targeting approach using siRNAs may provide a novel therapeutic option for diabetic retinopathy.

Inhibition of adhesion molecule expression on human venous endothelial cells by non-viral siRNA transfection

Objective:

Expression of adhesion molecule receptors on venous endothelial cells crucially influences the fate of venous grafts by mediating leukocyte-endothelium interactions. These interactions include adhesion of leuko-cytes to the endothelium, followed by transendothelial migration, leading to neointimal hyperplasia (NIH) and finally graft occlusion. Therefore, inhibition of adhesion molecule expression may be a promising strategy to improve the quality of venous grafts.We tested the efficiency of non-viral transfection of human venous endothe-lial cells (HVEC) with short interfering RNA (siRNA) to specifically down-regulate adhesion molecule expression.

Methods:

Primary cultures of HVEC were examined for expression of the adhesion molecules ICAM1, VCAM1 and E-selectin (SELE) after non viral siRNA transfection. Adhesion molecule expression was measured by flow cytom-etry, real-time polymerase chain reaction and immunoblotting after stimulation with TNF-α, an inflammatory cytokine.

Results:

Non-transfected cells showed a strong increase of adhesion molecule expression following cytokine stimulation (P < 0.01). Upon transfection with specific siRNAs a sixfold decrease in ICAM1 (P < 0.001) and SELE expression and cell positivity (P < 0.05) and a twofold decrease in VCAM1 expression and cell positiv-ity (P < 0.01) Pcould be observed. SiRNA-mediated gene suppression of adhesion molecules was also reflected by corresponding decreases in adhesion protein and transcript levels.

Conclusions:

The expression of adhesion molecules on HVECs can be effectively inhibited by specific siRNAs using a safe, non-viral transfection approach. This is a promising tool to pre-condition venous bypass grafts in order to interfere with endothelium-leukocyte interactions and to prohibit neointima thickening or ath-erosclerosis, which are regarded to be the most important causes of venous graft failure.

Lung ischemia-reperfusion injury: implications of oxidative stress and platelet-arteriolar wall interactions

Pulmonary ischemia-reperfusion (IR) injury may result from trauma, atherosclerosis, pulmonary embolism, pulmonary thrombosis and surgical procedures such as cardiopulmonary bypass and lung transplantation. IR injury induces oxidative stress characterized by formation of reactive oxygen (ROS) and reactive nitrogen species (RNS). Nitric oxide (NO) overproduction via inducible nitric oxide synthase (iNOS) is an important component in the pathogenesis of IR. Reaction of NO with ROS forms RNS as secondary reactive products, which cause platelet activation and upregulation of adhesion molecules. This mechanism of injury is particularly important during pulmonary IR with increased iNOS activity in the presence of oxidative stress. Platelet-endothelial interactions may play an important role in causing pulmonary arteriolar vasoconstriction and post-ischemic alveolar hypoperfusion. This review discusses the relationship between ROS, RNS, P-selectin, and platelet-arteriolar wall interactions and proposes a hypothesis for their role in microvascular responses during pulmonary IR.