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For cystic fibrosis gene therapy, the aerosolization of genetic materials is the most relevant delivery strategy to reach the airway epithelium. However, aerosolized formulations have to resist shear forces while maintaining the integrity of plasmid DNA (pDNA) during its journey from the nebulization to the epithelial cells. Herein, we compared the efficiency of gene delivery by aerosolization of two types of formulations: (i) BSV163, a branched cationic amphiphilic compound, co-formulated with different DOPE ratios (mol/mol) and DMPE-PEG5000 and (ii) 25 KDa branched polyethylenimine (b-PEI)-based formulation used as control. This study also aims to determine whether BSV163-based formulations possess the ability to resist the nebulization mechanisms and protect the nucleic acids (pDNA) cargo. Therefore, two CpG free plasmids (pGM144 or pGM169) encoding either the luciferase reporter gene or hCFTR respectively were used. Air-Liquid Interface (ALI) cell-culture was selected as an in-vitro model for aerosol experiments due to its closer analogy with in vivo morphology. Results highlighted that DOPE ratio influences the capacity of the BSV163 based-formulations to mediate high transfection efficacies. Furthermore, we proved that addition of DMPE-PEG5000 upon the formation of the BSV163/DOPE (1/1) lipid film instead of post-insertion led to a higher transgene expression. The aerosolization of this formulation on ALI cell-culture was more efficient than the use of b-PEI-based formulation.

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The objective of this study was to characterize the effects of multiple nasal prong interface configurations on nasal depositional loss of pharmaceutical aerosols in a preterm infant nose-throat (NT) airway model. Benchmark in vitro experiments were performed in which a spray-dried powder formulation was delivered to a new preterm NT model with a positive-pressure infant air-jet dry powder inhaler using single- and dual-prong interfaces. These results were used to develop and validate a computational fluid dynamics (CFD) model of aerosol transport and deposition in the NT geometry. The validated CFD model was then used to explore the NT depositional characteristic of multiple prong types and configurations. The CFD model highlighted a turbulent jet effect emanating from the prong(s). Analysis of NT aerosol deposition efficiency curves for a characteristic particle size and delivery flowrate (3 µm and 1.4 L/min (LPM)) revealed little difference in NT aerosol deposition fraction (DF) across the prong insertion depths of 2-5 mm (DF = 16-24%) with the exception of a single prong with 5-mm insertion (DF = 36%). Dual prongs provided a modest reduction in deposition vs. a single aerosol delivery prong at the same flow for insertion depths < 5 mm. The presence of the prongs increased nasal depositional loss by absolute differences in the range of 20-70% compared with existing correlations for ambient aerosols. In conclusion, the use of nasal prongs was shown to have a significant impact on infant NT aerosol depositional loss prompting the need for prong design alterations to improve lung delivery efficiency.

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Due to the alarming spread of bacterial resistance to conventional drugs, the sole use of antibiotics to fight lung infections in cystic fibrosis (CF) is not resolutive, and novel strategies to replace or complement the use of antibiotics are highly desirable. Among these strategies, the use of probiotics is emerging as a particularly attractive approach. Probiotic administration via the oral route has demonstrated an ability to improve lung function and to reduce infection and exacerbation rates in CF patients through mechanisms mainly attributable to the gut-lung axis. Nevertheless, some studies reported no beneficial effect of probiotic intake suggesting that there is margin for improvement of such innovative intervention in CF. The present review aims to address the rationale behind probiotic use in CF and discuss the hypothesis that nasal/aerosol administration of appropriate probiotic strains may help to exert a direct beneficial effect on the respiratory tract, increasing the effectiveness of probiotic interventions in CF patients.

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Background: An infant air-jet dry powder inhaler (DPI) platform has recently been developed that in combination with highly dispersible spray-dried powder formulations can achieve high-efficiency aerosolization with low actuation air volumes. The objective of this study was to investigate modifications to the nasal interface section of this platform to improve the aerosol delivery performance through preterm nose-throat (NT) models. Methods: Aerosol delivery performance of multiple nasal interface flow pathways and prong configurations was assessed with two in vitro preterm infant NT models. Two excipient-enhanced growth (EEG) dry powder formulations were explored containing either l-leucine or trileucine as the dispersion enhancer. Performance metrics included aerosol depositional loss in the nasal interface, deposition in the NT models, and tracheal filter deposition, which was used to estimate lung delivery efficiency. Results: The best performing nasal interface replaced the straight flexible prong of the original gradual expansion design with a rigid curved prong (∼20° curvature). The prong modification increased the lung delivery efficiency by 5%-10% (absolute difference) depending on the powder formulation. Adding a metal mesh to the flow pathway, to dissipate the turbulent jet, also improved lung delivery efficiency by ∼5%, while reducing the NT depositional loss by a factor of over twofold compared with the original nasal interface. The platform was also found to perform similarly in two different preterm NT models, with no statistically significant difference between any of the performance metrics. Conclusions: Modifications to the nasal interface of an infant air-jet DPI improved the aerosol delivery through multiple infant NT models, providing up to an additional 10% lung delivery efficiency (absolute difference) with the lead design delivering ∼57% of the loaded dose to the tracheal filter, while performance in two unique preterm airway geometries remained similar.

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Inhaled antibiotic treatment of cystic fibrosis-related bacterial biofilm infections is challenging because of the pathological environment of the lungs. Here, we present an "environment-adaptive" nanoparticle composed of a solid poly lactic-co-glycolic acid (PLGA) core and a mucus-inert, enzymatically cleavable shell of d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) for the site-specific delivery of antibiotics to bacterial biofilms via aerosol administration. The hybrid nanoparticles with ultrasmall size were self-assembled via a nanoprecipitation process by using a facile microfluidic method. The interactions of the nanoparticles with the biological barriers were comprehensively investigated by using cutting-edge techniques (e.g., quartz crystal microbalance with dissipation monitoring, total internal reflection fluorescence microscopy-based particle tracking, in vitro biofilm model cultured in a flow-chamber system, and quantitative imaging analysis). Our results suggest that the mucus-inert, enzymatically cleavable TPGS shell enables the nanoparticles to penetrate through the mucus, accumulate in the deeper layer of the biofilms, and serve as sustained release depot, thereby improving the killing efficacy of azithromycin (a macrolide antibiotic) against biofilm-forming Pseudomonas aeruginosa. In conclusion, the ultrasmall TPGS-PLGA hybrid nanoparticles represent an efficient delivery system to overcome the multiple barriers and release antibiotics in a sustained manner in the vicinity of the biofilm-forming bacteria.

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Preparations of palytoxin (PLTX, derived from Japanese Palythoa tuberculosa) and the congeners 42-OH-PLTX (from Hawaiian P. toxica) and ovatoxin-a (isolated from a Japanese strain of Ostreopsis ovata), as well as a 50:50 mixture of PLTX and 42-OH-PLTX derived from Hawaiian P. tuberculosa were characterized as to their concentration, composition, in-vitro potency and interaction with an anti-PLTX monoclonal antibody (mAb), after which they were evaluated for lethality and tissue histopathology after intraperitoneal (IP) and aerosol administration to rats. Once each preparation was characterized as to its toxin composition by LC-HRMS and normalized to a total PLTX/OVTX concentration using HPLC-UV, all four preparations showed similar potency towards mouse erythrocytes in the erythrocyte hemolysis assay and interactions with the anti-PLTX mAb. The IP LD50 values derived from these experiments (0.92, 1.93, 1.81 and 3.26 µg/kg, for the 50:50 mix, 42-OH-PLTX, PLTX, and ovatoxin-a, respectively) were consistent with published values, although some differences from the published literature were seen. The aerosol LD50 values (0.063, 0.045, 0.041, and 0.031 µg/kg for the 50:50 mix, 42-OH PLTX, PLTX, and ovatoxin-a, respectively) confirmed the exquisite potency of PLTX suggested by the literature. The tissue histopathology of the different toxin preparations by IP and aerosol administration were similar, albeit with some differences. Most commonly affected tissues were the lungs, liver, heart, salivary glands, and adrenal glands. Despite some differences, these results suggest commonalities in potency and mechanism of action among these PLTX congeners.

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