Delivery of the p38 MAPkinase Inhibitor SB202190 to Angiogenic Endothelial Cells:  Development of Novel RGD-Equipped and PEGylated Drug−Albumin Conjugates Using Platinum(II)-Based Drug Linker Technology

Abstract

Endothelial cells play an important role in inflammatory disorders, as they control the recruitment of leukocytes into inflamed tissue and the formation of new blood vessels. Activation of p38MAP kinase results in the production of proinflammatory cytokines and the expression of adhesion molecules. P38MAP kinase inhibitors are therefore considered important candidates for the treatment of inflammatory disorders. In the present study, we propose a novel strategy to counteract these processes by delivery of the p38MAP kinase inhibitor SB202190 into angiogenic endothelial cells. A drug-targeting conjugate was developed by conjugation of SB202190 to human serum albumin (HSA) using a novel platinum-based linker. Specificity for angiogenic endothelial cells was introduced by conjugation of cyclic RGD-peptides via bifunctional polyethylene glycol linkers. The final products contained an average of nine SB202190 and six RGDPEG groups per albumin. The platinum-based linker displayed high stability in buffers and culture medium, but released SB202190 slowly upon competition with sulfur-containing ligands like glutathione. RGDPEG-SB-HSA bound to R v3 -integrin expressing endothelial cells (human umbilical cord vein endothelial cells) with low nanomolar affinity and was subsequently internalized. When HUVEC were treated with TNF to induce inflammatory events, pretreatment with RGDPEG-SB-HSA partially inhibited proinflammatory gene expression (IL-8, E-selectin; 30% inhibition) and secretion of cytokines (IL-8, 34% inhibition). We conclude that the developed RGDPEG-SB-HSA conjugates provide a novel means to counteract inflammation disorders such as rheumatoid arthritis.

Rational Design of RGD–Albumin Conjugates for Targeted Delivery of the VEGF‐R Kinase Inhibitor PTK787 to Angiogenic Endothelium

“…We previously showed that the ULS-based coordination linkage is stable in serum, while drug is released upon competition with sulfur-containing ligands such as glutathione, of which high concentrations are found intracellularly. [17,18] We expect a similar release mechanism for the PTK787-albumin conjugates. In future studies, we will investigate the targeting capacity of these compounds and their tumor growth inhibitory properties.…”

“…Our drug-ULS linkage strategy is furthermore applicable to other drugs and carriers. [17][18][19] Optimization of the ligand-targeted drug-delivery conjugates by additional PEG modification not only improved pharmaceutical properties such as solubility and aggregation, but will also positively affect the behavior in vivo.…”

Tumor necrosis factor-α inhibits chondrogenic differentiation of synovial fibroblasts through p38 mitogen activating protein kinase pathways

“…Moreover, since our results suggest that the anti-anabolic activity of TNF-a is at least partially mediated by the p38 MAPK pathways, therapeutics targeting p38 MAPK may be able to stimulate neochondrogenesis in the damaged joints as well as to inhibit joint destruction. In fact, several p38 inhibitors are currently in clinical trials for RA [39][40][41]. However, it should be noted that SB203580 only partially restored the catabolic effects of TNF-a at 0.3 lM, and that higher doses of the compound rather abrogated its anticatabolic effect.…”

Protein– and Peptide–Drug Conjugates

“…Albumin conjugates can further be modified by PEGylation to impart hydrophilicity to improve the blood residence of conjugates (Temming, Lacombe, Schaapveld, et al, 2006;Temming, Lacombe, van der Hoeven, et al, 2006). Additionally, one can also go for coupling of targeting ligands such as cyclic or acyclic RGD, lactosamine and folate to the albumin to impart targeting potential to the conjugates (Dosio et al, 2009;Fiume et al, 2005;Temming, Lacombe, Schaapveld, et al, 2006;Temming, Lacombe, van der Hoeven, et al, 2006;Temming, Meyer, Zabinski, et al, 2006). The high endogenous availability of albumin in blood has been conveniently exploited to prepare in situ albumin-drug conjugates using chemically modified drugs with maleimide group which binds to serum albumin when injected in blood stream.…”