Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
Add more filters










Database
Language
Publication year range
1.
J Pharm Sci ; 98(2): 606-19, 2009 Feb.
Article in English | MEDLINE | ID: mdl-18563833

ABSTRACT

Tight junctions (TJs) play an important role in regulating paracellular drug transport. The aim of this study was to identify lipids that rapidly and reversibly alter transepithelial electrical resistance (TER) and/or TJ permeability in epithelial tissue. In this study, we developed a screen for identifying lipids that alter TJ properties. Measurement of TER was used to monitor TJ activity on bronchial/tracheal epithelial tissues using a microtiter format. Among seven groups of lipids tested, four classes were identified as TJ modulators (sphingosines, alkylglycosides, oxidized lipids and ether lipids). Individual lipids within these four classes showed up to 95% TER reduction at noncytotoxic concentrations. Alkylglycosides, however, showed high cytotoxicity and low viability at concentrations (0.2-0.4%) reported to enhance transmucosal absorption (Ahsan et al., 2003, Int J Pham 251: 195-203). Several active lipids also showed enhanced permeation of FITC-labeled dextran (m.w. 3000). Immunofluorescence staining of PGPC-treated cells with antibodies against ZO-1, occludin and claudin 4 showed no detectable changes in TJ structural morphology, indicating that a nondestructive, submicroscopic alteration in TJ function may be involved in TER reduction and permeation enhancement. This study demonstrates that three new classes of lipids, excluding alkylglycosides, show potential utility for transmucosal drug delivery.


Subject(s)
Drug Carriers , Epithelial Cells/drug effects , Excipients/pharmacology , Membrane Lipids/pharmacology , Respiratory Mucosa/drug effects , Tight Junctions/drug effects , Cell Survival/drug effects , Cells, Cultured , Dextrans/metabolism , Dose-Response Relationship, Drug , Electric Impedance , Epithelial Cells/metabolism , Ethers/pharmacology , Excipients/toxicity , Fluoresceins/metabolism , Fluorescent Antibody Technique , Glycosides/pharmacology , Humans , Membrane Lipids/metabolism , Membrane Lipids/toxicity , Oxidation-Reduction , Permeability , Respiratory Mucosa/cytology , Respiratory Mucosa/metabolism , Sphingosine/pharmacology , Tight Junctions/metabolism
2.
J Pharm Sci ; 95(6): 1364-71, 2006 Jun.
Article in English | MEDLINE | ID: mdl-16625659

ABSTRACT

Previously, a novel tight junction modulating (TJM) peptide was described affording a transient, reversible lowering of transepithelial electrical resistance (TER) in an in vitro model of nasal epithelial tissue. In the current report, this peptide has been further evaluated for utility as an excipient in transepithelial drug formulations. Chemical stability was optimal at neutral to acidic pH when stored at or below room temperature, conditions relevant to therapeutic formulations. The TJM peptide was tested in the in vitro tissue model for potential to enhance permeation of a low-molecular-weight (LMW) drug, namely the acetylcholinesterase inhibitor galantamine, as well as three peptides, salmon calcitonin, parathyroid hormone 1-34 (PTH(1-34)), and peptide YY 3-36 (PYY(3-36)). In all cases, the TJM peptide afforded a dramatic improvement in drug permeation across epithelial tissue. In addition, a formulation containing PYY(3-36) and TJM peptide was dosed intranasally in rabbits, resulting in a dramatic increase in bioavailability. The TJM peptide was as or more effective in enhancing PYY(3-36) permeation in vivo at a 1000-fold lower molar concentration compared to using LMW enhancers. Based on these in vitro and in vivo data, the novel TJM peptide represents a promising advancement in intranasal formulation development.


Subject(s)
Drug Delivery Systems , Peptides , Tight Junctions/metabolism , Administration, Intranasal , Animals , Area Under Curve , Biological Availability , Calcitonin/administration & dosage , Calcitonin/pharmacokinetics , Chemistry, Pharmaceutical , Drug Stability , Electric Impedance , Epithelial Cells/metabolism , Galantamine/administration & dosage , Galantamine/pharmacokinetics , Hydrogen-Ion Concentration , In Vitro Techniques , Parathyroid Hormone/administration & dosage , Parathyroid Hormone/pharmacokinetics , Peptide Fragments/administration & dosage , Peptide Fragments/pharmacokinetics , Peptide YY/administration & dosage , Peptide YY/pharmacokinetics , Peptides/administration & dosage , Peptides/pharmacokinetics , Peptides/therapeutic use , Permeability , Rabbits
3.
Am J Pathol ; 165(4): 1423-31, 2004 Oct.
Article in English | MEDLINE | ID: mdl-15466406

ABSTRACT

Bacterial lipopolysaccharide (LPS) via its activation of Toll-like receptor-4 contributes to much of the vascular injury/dysfunction associated with gram-negative sepsis. Inhibition of de novo gene expression has been shown to sensitize endothelial cells (EC) to LPS-induced apoptosis, the onset of which correlates with decreased expression of FLICE-like inhibitory protein (FLIP). We now have data that conclusively establish a role for FLIP in protecting EC against LPS-induced apoptosis. Overexpression of FLIP protected against LPS-induced apoptosis, whereas down-regulation of FLIP using antisense oligonucleotides sensitized EC to direct LPS killing. Interestingly, FLIP overexpression suppressed NF-kappaB activation induced by LPS, but not by phorbol ester, suggesting a specific role for FLIP in mediating LPS activation. Conversely, mouse embryo fibroblasts (MEF) obtained from FLIP -/- mice showed enhanced LPS-induced NF-kappaB activation relative to those obtained from wild-type mice. Reconstitution of FLIP-/- MEF with full-length FLIP reversed the enhanced NF-kappaB activity elicited by LPS in the FLIP -/- cells. Changes in the expression of FLIP had no demonstrable effect on other known LPS/Tlr-4-activated signaling pathways including the p38, Akt, and Jnk pathways. Together, these data support a dual role for FLIP in mediating LPS-induced apoptosis and NF-kappaB activation.


Subject(s)
Apoptosis/physiology , Carrier Proteins/metabolism , Endothelial Cells/metabolism , Intracellular Signaling Peptides and Proteins , Lipopolysaccharides/pharmacology , NF-kappa B/metabolism , Animals , Antigens, Bacterial/immunology , Antigens, Bacterial/metabolism , Apoptosis/drug effects , CASP8 and FADD-Like Apoptosis Regulating Protein , Carrier Proteins/drug effects , Caspases/drug effects , Caspases/metabolism , Cells, Cultured , Cycloheximide/pharmacology , Endothelial Cells/drug effects , Endothelial Cells/pathology , Enzyme Activation/drug effects , Enzyme-Linked Immunosorbent Assay , Fibroblasts/drug effects , Fibroblasts/metabolism , Humans , Immunoblotting , NF-kappa B/drug effects , Protein Synthesis Inhibitors/pharmacology , Transfection
4.
Microb Pathog ; 35(2): 87-93, 2003 Aug.
Article in English | MEDLINE | ID: mdl-12901848

ABSTRACT

Shiga toxin (Stx) has been implicated in the pathogenesis of several human and animal disease states. A key host target of Stx is the endothelial cell. Stx induces endothelial cell apoptosis through a mechanism that remains unknown. In the present report, we demonstrate that Stx-1 and Stx-2 inhibit endothelial cell expression of the anti-apoptotic Bcl-2 family member, Mcl-1. Decreased expression of Mcl-1 preceded the onset of Stx-induced apoptosis. Further, Stx-1-induced decrements in Mcl-1 expression correlated in a dose-dependent manner with sensitization to Stx-1-induced apoptosis. Finally, inhibition of Mcl-1 degradation with the proteasome inhibitor, lactacystin, protected against Stx-1-induced apoptosis. These combined data suggest a role for Mcl-1 in protecting endothelial cells against Stx-1-induced apoptosis.


Subject(s)
Apoptosis , Endothelium, Vascular/cytology , Endothelium, Vascular/physiology , Neoplasm Proteins/biosynthesis , Proto-Oncogene Proteins c-bcl-2 , Shiga Toxin 1/toxicity , Shiga Toxin 2/toxicity , Caspase 3 , Caspases/metabolism , Cell Line , Histones/metabolism , Humans , Myeloid Cell Leukemia Sequence 1 Protein , Neoplasm Proteins/physiology
SELECTION OF CITATIONS
SEARCH DETAIL
...