Orphan Nuclear Receptors as Targets for Drug DevelopmentMukherjee, Subhajit; Mani, Sridhar
doi: 10.1007/s11095-010-0117-7pmid: 20372994
Orphan nuclear receptors regulate diverse biological processes. These important molecules are ligand-activated transcription factors that act as natural sensors for a wide range of steroid hormones and xenobiotic ligands. Because of their importance in regulating various novel signaling pathways, recent research has focused on identifying xenobiotics targeting these receptors for the treatment of multiple human diseases. In this review, we will highlight these receptors in several physiologic and pathophysiologic actions and demonstrate how their functions can be exploited for the successful development of newer drugs.
Phospholipids and Lipid-Based Formulations in Oral Drug DeliveryFricker, Gert; Kromp, Torsten; Wendel, Armin; Blume, Alfred; Zirkel, Jürgen; Rebmann, Herbert; Setzer, Constanze; Quinkert, Ralf-Olaf; Martin, Frank; Müller-Goymann, Christel
doi: 10.1007/s11095-010-0130-xpmid: 20411409
Phospholipids become increasingly important as formulation excipients and as active ingredients per se. The present article summarizes particular features of commonly used phospholipids and their application spectrum within oral drug formulation and elucidates current strategies to improve bioavailability and disposition of orally administered drugs. Advantages of phospholipids formulations not only comprise enhanced bioavailability of drugs with low aqueous solubility or low membrane penetration potential, but also improvement or alteration of uptake and release of drugs, protection of sensitive active agents from degradation in the gastrointestinal tract, reduction of gastrointestinal side effects of non-steroidal anti-inflammatory drugs and even masking of bitter taste of orally applied drugs. Technological strategies to achieve these effects are highly diverse and offer various possibilities of liquid, semi-liquid and solid lipid-based formulations for drug delivery optimization.
Gene Therapy: A Pharmacokinetic/Pharmacodynamic Modelling OverviewParra-Guillén, Zinnia; González-Aseguinolaza, Gloria; Berraondo, Pedro; Trocóniz, Iñaki
doi: 10.1007/s11095-010-0136-4pmid: 20387096
Since gene therapy started over 20 years ago, more than one-thousand clinical trials have been carried out. Nonviral vectors present interesting properties for their clinical application, but their efficiency in vivo is relatively low, and further improvements in these vectors are needed. Elucidating how nonviral vectors behave at the intracellular level is enlightening for vector improvement and optimization. Model-based approach is a powerful tool to understand and describe the different processes that gene transfer systems should overcome inside the body. Model-based approach allows for proposing and predicting the effect of parameter changes on the overall gene therapy response, as well as the known application of the pharmacokinetic/pharmacodynamic modelling in conventional therapies. The objective of this paper is to critically review the works in which the time-course of naked or formulated DNA have been quantitatively studied or modelled.
Potential Aggregation-Prone Regions in Complementarity-Determining Regions of Antibodies and Their Contribution Towards Antigen Recognition: A Computational AnalysisWang, Xiaoling; Singh, Satish K.; Kumar, Sandeep
doi: 10.1007/s11095-010-0143-5pmid: 20422267
ABSTRACTPurposeTo analyze contribution of short aggregation-prone regions (APRs), which may self-associate via cross-β motif and were earlier identified in therapeutic mAbs, towards antigen recognition via structural analyses of antibody-antigen complexes.MethodsA dataset of 29 publically available high-resolution crystal structures of Fab-antigen complexes was collected. Contribution of APRs towards the surface areas of the Fabs buried by the cognate antigens was computed. Propensities of amino acids to occur in APRs and to be involved in antigen binding were compared. Coincidence between APRs and individual CDR loops was examined.ResultsAll Fabs in the dataset contain at least one APR in CDR loops and adjacent framework β-strands. The average contribution of APRs towards buried surface area of Fabs is 16.0 ± 10.7%. Aggregation and antigen recognition may be coupled via aromatic residues (Tyr, Trp), which occur with high propensities in both APRs and antigen binding sites. APRs are infrequent in the heavy chain CDR 3 (H3) loops (7%), but are frequent in H2 loops (45%).ConclusionsCo-incidence of APRs with antigen recognition sites can potentially lead to the loss of function upon aggregation. Rational structure-based design or selection strategies are suggested for biotherapeutics with improved druggability while maintaining potency.
Cellular Entry of G3.5 Poly (amido amine) Dendrimers by Clathrin- and Dynamin-Dependent Endocytosis Promotes Tight Junctional Opening in Intestinal EpitheliaGoldberg, Deborah S.; Ghandehari, Hamidreza; Swaan, Peter W.
doi: 10.1007/s11095-010-0153-3pmid: 20411406
ABSTRACTPurposeThis study investigates the mechanisms of G3.5 poly (amido amine) dendrimer cellular uptake, intracellular trafficking, transepithelial transport and tight junction modulation in Caco-2 cells in the context of oral drug delivery.MethodsChemical inhibitors blocking clathrin-, caveolin- and dynamin-dependent endocytosis pathways were used to investigate the mechanisms of dendrimer cellular uptake and transport across Caco-2 cells using flow cytometry and confocal microscopy.ResultsDendrimer cellular uptake was found to be dynamin-dependent and was reduced by both clathrin and caveolin endocytosis inhibitors, while transepithelial transport was only dependent on dynamin- and clathrin-mediated endocytosis. Dendrimers were quickly trafficked to the lysosomes after 15 min of incubation and showed increased endosomal accumulation at later time points, suggesting saturation of this pathway. Dendrimers were unable to open tight junctions in cell monolayers treated with dynasore, a selective inhibitor of dynamin, confirming that dendrimer internalization promotes tight junction modulation.ConclusionG3.5 PAMAM dendrimers take advantage of several receptor-mediated endocytosis pathways for cellular entry in Caco-2 cells. Dendrimer internalization by dynamin-dependent mechanisms promotes tight junction opening, suggesting that dendrimers act on intracellular cytoskeletal proteins to modulate tight junctions, thus catalyzing their own transport via the paracellular route.