Erik Anna Leonardus Biessen

Gallic Acid Antagonizes P-Selectin–Mediated Platelet–Leukocyte Interactions Implications for the French Paradox

Background—Current paradigm attributes the low incidence of cardiovascular disorders in Mediterranean countries despite a high saturated fat intake, the “French paradox,” to the antioxidant capacity of red wine polyphenols. Conceivably, other antiinflammatory pathways may contribute to at least a similar extent to the atheroprotective activity of these polyphenols. We have investigated whether gallic acid (GA), an abundant red wine polyphenol, modulates the activity of P-selectin, an adhesion molecule that is critically involved in the recruitment of inflammatory cells to the vessel wall and thus in atherosclerosis. Methods and Results—GA potently inhibited the binding of a peptide antagonist (IC50, 7.2 &mgr;mol/L) and biotin-PAA-Lea-SO3H, an established high-affinity ligand, to P-selectin (IC50, 85 &mgr;mol/L). Under dynamic flow conditions, GA markedly and dose dependently attenuated the rolling of monocytic HL60 cells over P-selectin-transfected Chinese hamster ovary cells (EC50, 14.5 &mgr;mol/L) while increasing the velocity of P-selectin-dependent rolling of human blood leukocytes over a platelet monolayer. In vivo tests established that GA administration to normolipidemic C57/Bl6 and aged atherosclerotic apolipoprotein E–deficient mice impaired the baseline rolling of conjugates between activated platelets and circulating monocytes over femoral vein endothelium, as judged by online video microscopy (ED50, 1.7±0.3 and 1.5±0.4 mg · kg−1 · h−1, respectively). Conclusions—Our findings provide a solid mechanistic foundation through which GA intervenes in major inflammatory pathobiologies by binding and antagonizing P-selectin.

Receptor-Dependent Cell Specific Delivery of Antisense Oligonucleotides

Oligodeoxynucleotides (ODNs) have been shown to inhibit gene expression at various levels both in vitro and in vivo [1–4]. In vivo, the efficacy of ODN-induced regulation of genes in specific cell types may be suboptimal due to poor accumulation of ODNs in these cells. In addition, untimely elimination of ODNs via renal clearance, degradation and scavenger receptor-mediated uptake [6] may further impair their therapeutic activity. These hurdles can be at least partly overcome by targeted delivery of the ODNs to the desired site of action. A number of approaches have been suggested to facilitate the entry of polyanionic ODNs into the aimed target cell [7–12]. Neutral and cationic liposomes are considered to be attractive ODN carriers since they markedly enhance cellular uptake under in vitro conditions. Like native ODNs, however, liposomally formulated ODNs are mainly captured by cells of the reticulo-endothelial system in lungs, spleen and liver [13–15], as a result of which the ODN concentration in the target cell will be suboptimal. After local delivery of ODNs encapsulated in virus capsid-coated liposomes, Morishita et al. [16] could enhance ODN uptake by vascular endothelial cells leading to cell-specific antisense effects. Nevertheless, this approach is not feasible for specific delivery of ODNs to most other cell types like the parenchymal liver cell (PC).