Toll-like receptor 2 regulates the barrier function of human bronchial epithelial monolayers through atypical protein kinase C zeta, and an increase in expression of claudin-1.

We investigated the role of Toll-like receptor (TLR) 2 in maintaining the integrity of the airway epithelial barrier using the human bronchial epithelial cell line Calu-3. Activation of TLR2 by its ligands, Pam3CysSK4 and Peptidoglycan showed a concentration dependent increase in epithelial barrier function, as measured by transepithelial electrical resistance (TEER). This was confirmed by a decrease in paracellular flux of fluorescein sodium. This TLR2 induced increase in TEER was significantly reduced by pretreatment with polyclonal anti-human TLR2-neutralizing antibody. TLR2 stimulation in Calu-3 cell monolayers resulted in an increased expression of the tight junction proteins claudin-1 and ZO-1, and a decreased expression of occludin, at both the mRNA and protein levels. A pseudosubstrate inhibitor to PKCζ significantly prevented the TLR2 mediated increase in barrier function. It also prevented the increase in claudin-1 in a concentration dependent manner up to 1 µM. TLR2 stimulation led to an increase in phosphorylation of atypical PKC ζ, which was prevented by the pseudosubstrate inhibitor in a concentration dependent manner. Taken together, our observations support a model whereby increased tight junction barrier function induced by activation of TLR2 occurs through increased expression of claudin-1, and through modulation of PKC ζ activity.

Multifunctional PLGA-based nanoparticles encapsulating simultaneously hydrophilic antigen and hydrophobic immunomodulator for mucosal immunization.

We describe here the development of nanoparticles made from poly(lactic-co-glycolic acid) (PLGA) able to deliver an encapsulated antigen with a Toll-Like Receptor-7 (TLR-7) agonist as immunostimulatory signal and coated with a muco-adhesive chitosan-derivate layer. The potential to stimulate an immune response of these vaccine formulations in the absence or presence of the TLR-7 agonist at the systemic and mucosal level were evaluated in mice following subcutaneous or nasal administrations. Intranasally immunized mice developed a high systemic immune response equivalent to mice injected subcutaneously. However, mucosal immune responses were only induced at local and distal sites in mucosally immunized animals. The adjuvant effect of imiquimod on the polarization of the immune response was only detected at local sites, which tends to increase safety of this vaccine delivery system.

Cellular cytotoxicity and in-vivo biodistribution of docetaxel poly(lactide-co-glycolide) nanoparticles.

Docetaxel (DTX) is one of the most effective antineoplastic drugs. However, its current clinical administration, formulated in tween80, causes serious side effects. This study is focused on preparation and evaluation of poly(lactide-co-glycolide) nanoparticles (NPs) containing DTX to remove tween80. Drug encapsulation efficiency, in-vitro drug release, cellular cytotoxicity, and in-vivo biodistribution of NPs in mice after intravenous administration were investigated. The average diameter of the NPs was approximately 172-178 nm with encapsulation efficiency of 68%. A burst release of approximately 30% (w/w) of the loaded drug followed by a sustained release profile was observed. Cellular mortality of the NPs was more than or at least as great as DTX free drug; for example, cell viability measured at 100 nmol/l drug concentration was decreased from 50.9% for DTX free drug to 15.9% for the NP formulation after 48 h incubation with T47D cells. The DTX plasma amount remained at a good level (13% of the initial dose) in the NP formulation compared with the DTX conventional formulation, which is approximately 0.5% of the initial dose, was present in plasma up to 2 h. Poly(lactide-co-glycolide) NPs containing DTX prepared in this study may be regarded as a suitable and superior formulation for the current formulation in the market containing tween80 with improved cancerous cell mortality and biodistribution characteristics.

Development and validation of a stability-indicating method for the quantitation of Paclitaxel in pharmaceutical dosage forms.

A simple, rapid stability-indicating isocratic assay has been developed and validated for the determination of Paclitaxel (PTX) in commercial injection formulations. The assay is performed using a Nucleosil RP-18 (5 microm, 250 x 4.0 mm i.d) column protected by a Nucleosil C(18) precolumn (5 microm, 4.0 x 4.0 mm i.d.) with a mobile phase of methanol-water (80:20) and UV detection at 230 nm. The method was found to be specific for PTX in the presence of degradation products with an overall analytical run time of ~ 9 min. Accuracy reported as % bias was found to be 0.1-2.5% bias for all samples tested. Intra-assay precision (repeatability) was found to be 0.22-2.65% RSD, while inter-day precision (intermediate precision) was found to be 1.0-3.0% RSD for the samples studied. The calibration curve was found to be linear with the equation y = 29.78x + 7.65, and a linear regression coefficient of 0.9994 over the concentration range 0.05-20 microg/mL. The limits of quantitation and detection were 0.05 and 0.02 microg/mL, respectively. Taxol (30 mg/5 mL), a commercially available dosage form of PTX, was assayed and 100.6-103.6% of the label claim was recovered.

Preparation of pegylated nano-liposomal formulation containing SN-38: In vitro characterization and in vivo biodistribution in mice.

7-Ethyl-10-hydroxy-camptothecin (SN-38), a metabolite of irinotecan x HCl, is poorly soluble in aqueous solutions and practically insoluble in most physiologically compatible and pharmaceutically acceptable solvents. Formulation of SN-38 in concentrated pharmaceutical delivery systems for parenteral administration is thus very difficult. Due to their biocompatibility and low toxicity, liposomes were considered for the delivery of SN-38. In this study, pegylated liposomes with distearoylphosphatidylcholine, distearoylphosphatidylethanolamine containing SN-38 were prepared and their characteristics, such as particle size, encapsulation efficiency, in vitro drug release and biodistribution, were investigated. The particle size of liposomes was in the range of 150--200 nm. The encapsulation efficiency and in vitro release rate of pegylated liposomes was higher than those of non-pegylated liposomes. As expected, the distribution of pegylated liposomes in body organs such as liver, kidney, spleen and lung was considerably lower than that of non-pegylated liposomes. Also, their blood concentration was at least 50 % higher than that of non-pegylated liposomes.

Docetaxel-albumin conjugates: preparation, in vitro evaluation and biodistribution studies.

Docetaxel (DTX) is one of the most active chemotherapeutic agents for treating metastatic breast cancer. Its aqueous solubility is very low, hence the available formulation of DTX for clinical use consists of high concentrations of tween80, which has been associated with several hypersensitivity reactions. To reduce the systemic toxicity of DTX as well as to avoid the use of tween80, in this study DTX was chemically conjugated with human serum albumin via a succinic spacer. A high-performance liquid chromatography method was developed for the determination of DTX-albumin conjugate. T47D and SKOV3 cells were used for the evaluation of the in vitro cytotoxicity of the conjugate by MTT assay. Studies were then done on balb/c mice to elucidate the tissue distribution of conjugates after intravenous administration. The albumin-conjugated formulation of DTX with the particle size of 90-110 nm showed enhanced solubility and in vivo characteristics and significantly higher cytotoxicity against tumor cells, for example, IC50 of 6.30 +/- 0.73 nM for T47D cell line compared to free DTX with IC50 of 39.4 +/- 1.75 nM. Conjugation also maintained DTX plasma level at 16.19% up to 2 h after injection compared with 2.51% for Taxotere, hence increasing the chance of nanoparticles uptake by tumor cells.

Folate-receptor-targeted delivery of docetaxel nanoparticles prepared by PLGA-PEG-folate conjugate.

For folate-receptor-targeted anticancer therapy, docetaxel (DTX) nanoparticles (NPs) were produced employing polylactide-co-glycolide-polyethylene glycol-folate (PLGA-PEG-FOL) conjugate. The FOL-conjugated di-block copolymer was synthesized by coupling the PLGA-PEG-NH(2) di-block copolymer with an activated folic acid. It was expected that FOL moieties were exposed on the micellar surface. The conjugates assisted in the formation of DTX NPs with an average size of 200 nm in diameter through an emulsification/solvent diffusion method. The FOL-targeted NPs showed a greater extent of intracellular uptake in FOL-receptor-positive cancer cells (SKOV3) in comparison with the non-targeted NPs, indicating that the FOL-receptor-mediated endocytosis mechanism could have a role in the cellular uptake of NPs. These results suggested that FOL-targeted DTX NPs could be a potentially useful delivery system for FOL-receptor-positive cancer cells.

PLGA nanoparticles of different surface properties: preparation and evaluation of their body distribution.

The opsonization or removal of nanoparticulate drug carriers from the body by the reticuloendothelial system (RES) is a major obstacle that hinders the efficiency of the nanoparticulate drug delivery systems. Therefore, several methods of camouflaging or masking nanoparticles (NPs) have been developed to increase their blood circulation half-life. In this study, rhodamine B isothiocyanate (RBITC) loaded NPs were fabricated by an emulsification/solvent diffusion method. The surface of NPs was then modified using either poly ethylene glycol (PEG) or block copolymer of ethylene oxide and propylene oxide, Poloxamer 407 (POL). The surface treatment was carried out using two different methods: (a) co-incorporation of the surface modifying agents (SMAs) into NPs and (b) the external surface adsorptions method and both of these methods were done only by physical incorporation of the SMAs into the NPs, without the need of special chemical reagents. The biodistribution properties of the NPs were then measured. The results confirmed that the surface treatment of the NPs using co-incorporation of the SMAs into NPs is more efficient in increasing the blood circulation half-life of the NPs when compared with the external surface adsorptions method.

Preparation and antibacterial activity evaluation of rifampicin-loaded poly lactide-co-glycolide nanoparticles.

Biodegradable polymers such as poly lactide-co-glycolides (PLGA) have been considered for the preparation of nanoparticles (NPs). In this study, rifampicin (RIF)-loaded PLGA NPs were fabricated by an emulsification/solvent diffusion method. The effect of several variables on the NPs' characteristics were evaluated, including the amount of RIF, amount of the poly vinyl alcohol as surfactant, and internal-phase volume and composition. The RIF encapsulation efficacy and the particle size distribution were optimized by varying these parameters. NPs were spherical with a relatively monodispersed size distribution. The effect of nanoencapsulation of RIF on the antibacterial activity of RIF against gram-positive and gram-negative bacteria was evaluated. It was shown that RIF NPs could considerably improve the RIF antibacterial efficacy.