The pathophysiology of obstructive pulmonary diseases, such as cystic fibrosis (CF), leads to the development of chronic infections in the respiratory tract. Thus, the symptomatic management of the disease requires, in particular, repetitive antibiotherapy. Besides these antibacterial treatments, certain pathologies, such as CF or chronic obstructive pulmonary disease (COPD), require the intake of many drugs. This simultaneous absorption may lead to undesirable drug interactions. For example, Orkambi® (lumacaftor/Ivacaftor, Vertex), a pharmacological drug employed to treat F508del patients, cannot be used with antibiotics such as rifampicin or rifabutin (rifamycin family) which are necessary to treat Mycobacteriaceae. As far as gene therapy is concerned, bacteria and/or biofilm in the airways present an additional barrier for gene transfer. Thus, aerosol administration of nanoparticles have to overcome many obstacles before allowing cellular penetration of therapeutic compounds. This review focusses on the development of aerosol formulations adapted to the respiratory tract and its multiple barriers. Then, formulations that are currently used in clinical applications are summarized depending on the active molecule delivered. Finally, we focus on new therapeutic approaches to reduce possible drug interactions by transferring the antibacterial activity to the nanocarrier while ensuring the transfection efficiency.

Introduction

Gene therapy is a therapeutic strategy based on gene transfer approaches. They allow the input of nucleic acid constructs inside eukaryotic cells in order to correct a genetic abnormality (e.g. hereditary genetic disorders) or to regulate the expression of genes (e.g. cancers application). In most cases, it is necessary to have a carrier capable of conveying these nucleic acids. In fact, nucleic acid constructs being anionic polymers, cannot, except in some specific cases, interact with the negatively charged plasma membranes. Synthetic vectors are amongst the existing gene transfer systems. In 1987, the first synthetic carrier (DOTMA: N-[1-(2,3-dioleyloxy) propyl]-N,N,N-trimethylammonium chloride), allowing the introduction of DNA into mammalian cells, was developed by Felgner and co-workers [1]. This family of carriers is now used in 4.6% of gene therapy clinical trials (http://www.wiley.com/legacy/wileychi/genmed/clinical/; the journal of gene medicine 2017). Unlike viral vectors, synthesis of chemical vectors is fully controlled and allows for mass production for high incidence pathologies. Moreover, they are, for the most part, neither immunogenic nor very cytotoxic [2,3]. This allows the re-administration of nucleic acid constructs, which is most often required since not only the DNA not integrate into the genome, but the expression of the transgene is a function of the lifetime of the transfected cell as well. Synthetic vectors are mainly cationic molecules that self-assemble with nucleic acids via electrostatic interactions that form polyplexes (polymers/nucleic acids) or lipoplexes (liposomes/nucleic acids) [36]. In addition to facilitating internalization in the eukaryotic cell, this encapsulation also makes it possible to protect nucleic acids from possible degradation (interaction or degradation by enzymes in the extra or intracellular environment).

Gene transfer systems based on cationic polymers are classified into four different families depending on the nature of the polymer (poly-L-lysine derivatives [7], derivatives of polyethyleneimine (PEI) [8], dendrimers [9], and chitosan [10]). Some other synthetic vectors are bio-inspired from phospholipids that form plasma membranes and are called cationic lipids [11]. These molecules of amphiphilic nature are composed of three parts: a polar head, a spacer, and a hydrophobic domain. Cationic lipids have been classified into four major subfamilies depending on the number of positive charges and the nature of the hydrophobic domain: monocationic, polycationic, cholesterol-derived monocationic, and cholesterol-derived polycationic. In order to improve transfection efficiency, numerous cationic lipids have been synthesized and many formulations have been derived. Phase IIb clinical trial conducted by the U.K. cystic fibrosis (CF) gene therapy consortium showed that the non-viral aerosolization gene therapy approach for CF application was beneficial and allowed CF patients to maintain their respiratory capabilities after an administration per month for a year (forced expiratory volume in 1 s (FEV1) + 3.7%) [12].

The intracellular barriers have been extensively studied in order to better understand how a gene transfer system should behave and know which essential properties are necessary for functional non-viral gene therapy, especially in the respiratory tract [1316]. Nevertheless, extracellular barriers such as mucus, bacteria, and inflammation are important and decisive primary barriers which determine the extent of the contact between the gene transfer systems and the target cells [1719]. The nature of bacterial flora in the pulmonary environment has not been taken into account in the evaluation of synthetic vectors nor in the clinical trial carried out by the British CF consortium [12]. Only pulmonary exacerbations were included as a clinical end point. However, some studies have shown that bacteria constitute an extracellular barrier that can oppose gene transfer [20,21]. If the airways do indeed seem to be the natural way to treat respiratory diseases, the effectiveness of the treatment has been slowed by the extra and intracellular barriers. This observation raises the question of both the mode of administration and the barriers faced by gene transfer. For example, the viral envelope of most recombinant vectors have difficulty withstanding the shear forces caused by an aerosol [22]. Then, for viruses still whole, their penetration into the hyperviscous mucus is difficult [23].

Currently, patients with pulmonary infections receive antibiotic therapy frequently. Taking any other treatment simultaneously, such as gene transfer, can create interactions and lead to a decrease in the expected beneficial effects. The new approach proposed in this review consists of developing formulations coupling simultaneously, the properties of gene transfer and the antibacterial effect. Meaning a single treatment will be administered in patients, decreasing the risks of drug interactions and increasing the therapeutic benefits. First, the anatomy of the airways, the mode of administration targetting these pathways, and their limits will be described. Then, the potential benefits of such an approach and the different formulations considered will be explained in terms of their clinical applications.

Direct lung delivery

The respiratory tract

The respiratory tract consists of the upper airways (nasal and oral cavities, pharynx, and larynx) and lower airways (trachea, bronchi, and segmental bronchi). The upper airways allow the filtration, the heating, and the humidification of the incoming air. The primary role of the respiratory system is to ensure gas exchanges between the air and the blood. This exchange is performed at the pulmonary alveoli stage. The lower airways have a tree-like structure (Figure 1). The trachea, corresponding to the trunk (120–150 mm in length with a diameter of 14–15 mm), divides into two main bronchi (right bronchus: 2.5 cm in length for a diameter of 15 mm and left bronchus: 5 cm in length for 11 mm width), which themselves divide into segmental bronchi. Finally, the following bronchioles (diameter less than 1 mm) end with air sacs. The tracheopulmonary tree is divided into three distinct areas according to their function in the transport of oxygen. The conduction area extending from the trachea to the bronchioles allows the air to be conveyed. In this area, there is no air-to-blood gas exchange. Whereas the transition area corresponding to the bronchioles participates in the gas exchange. Finally, the respiratory area comprising all the pulmonary alveoli allows for most of the gas exchange by diffusion. The decrease in respiratory function is often due to repeated aggression on the respiratory tract. For example, in smokers or in chronic obstructive pulmonary disease (COPD) patients, the inhaled toxicants will gradually destroy the cellular layers, leading to a reduction in gas exchange giving rise to an increase in the partial pressure of oxygen. Similarly, in CF patients, repeated cycles of infection and inflammation will lead to fibrosis of the pulmonary parenchyma and a decrease in respiratory function (measured by FEV1).

The organization and the structure of the respiratory tract

Figure 1
The organization and the structure of the respiratory tract

Abbreviation: PCL, periciliary layer.

Figure 1
The organization and the structure of the respiratory tract

Abbreviation: PCL, periciliary layer.

The structure of the airway epithelium varies depending on the section. The bronchi are lined with a pseudostratified epithelium, whereas in the bronchioles, the epithelium is simple cylindrical and then cuboidal. The tracheobronchial epithelium (trachea and bronchi) is composed of ciliated cells permitting mucociliary clearance, globlet cells, and basal cells (Figure 1). The ciliated cells allow the elimination of pollutants trapped on the surface’s liquid which covers the epithelium. This surface liquid (‘airway surface liquid’ (ASL)) is composed of periciliary layer (PCL) and mucus layer. Compared with the mucus, the PCL has a low viscosity [24]. The mucus is composed of salts, proteins (glycoproteins, mucins, mucoproteins), and water [25]. It corresponds to the product of secretions from different cells (globlet cells in the trachea and clara cells in the bronchioles). The hydration state of the surface liquid is dependent on the ionic transports (chloride ions and sodium ions in part) [26,27]. Some pathologies, such as CF, induce a defect in regulation or expression of the channels involved in ion transport, resulting in dehydration of the surface liquid and a defect in mucociliary clearance [28]. This hyperviscous mucus becomes a favorable environment for microbial infections’ development.

Targetting the respiratory tract by aerosolization

Aerosolization is currently the preferred mode of administration for airway targetting. This technique of administration is non-invasive and induces little stress for patients commonly treated with aerosol. For example, asthmatic patients inhale bronchodilators (terbutaline sulphate, salbutamol sulphate, ipratropium bromide) even before the age of 3 years. Aerosolization allows the passage of a liquid solution in the form of microdroplets. Several types of aerosolization systems exist: jet nebulizers, ultrasonic, or membrane nebulizers. Jet nebulization uses a compressed gas (air or oxygen) to generate microdroplets. With the ultrasonic system of nebulizers, the aerosol is formed by high-frequency vibration of a liquid. The microdroplets of the third type of aerosolization system are obtained after passage of the solution through a membrane. The size of the droplets formed varies according to the aerosolization system used [29]. The choice of the system is important because depositing the aerosol within the respiratory tract is defined by the size of the droplets formed [30]. Given the variable respiratory flow, the finest particles diffuse deeper at the alveolar level [31]. Three depositing mechanisms can be observed. The impaction phenomenon for droplets larger than 5 μm is due to the respiratory tract structure. Particles between 1 and 5 μm are sedimented, while droplets below 1 μm diffuse by Brownian motion in the bronchioles and the alveoli. The administered fluid volumes are very limited, same as the nasal instillation, because an excess of liquid can lead to drowning.

Pharmacokinetics of nanocomplexes after aerosol delivery

The major advantage of administration by inhalation is its pharmacological properties. Pharmacokinetics and pharmacodynamics indeed determine the therapeutic effect of a drug. Unlike the other major modes of administration, inhalation makes it possible to circumvent the blood circulation, and to avoid the first-pass effect of the liver which may lead to a reduction in the quantity of active principles reaching the targetting tissue and to potential side effects (Figure 2). For example, patients with type 1 Gaucher disease take an inhibitor of glocoyl ceramide synthase orally (eliglustat) [32]. To benefit from this treatment, a cytochrome P450 2D6 genotyping assay is required. The level of enzymatic activity of this cytochrome will determine the rate of metabolism of the drug and therefore the dose administered to the patient. This is also the case with certain classes of antibiotics. Amongst them, the aminoglycosides which bind the rRNAs (16S RNA) and thus block the translation of proteins are described as nephrotoxic and ototoxic agents when administered systemically [33]. The delivery of these antibiotics (example of gentamycin) by aerosolization has reduced these side effects [34]. The elimination of a drug also depends on the route of administration (Figure 3) [35]. If elimination does not occur fully, there are risks of accumulation which cause toxic side effects. When administered by inhalation, a large part of the active principle is eliminated by the mucociliary clearance and by exhalation. Nevertheless, the development of aerosolization systems has reduced the exhalation of treatments. The deposit site will determine the elimination kinetics [36]. The deeper the particles are deposited, the longer will be the elimination time.

Pharmacokinetics according to the administration used

Figure 2
Pharmacokinetics according to the administration used

The aerosolization allows direct targetting of the lungs and thus bypasses the blood circulation.

Figure 2
Pharmacokinetics according to the administration used

The aerosolization allows direct targetting of the lungs and thus bypasses the blood circulation.

Elimination pathways of an inhaled drug

Figure 3
Elimination pathways of an inhaled drug

Some of the inhaled drugs are eliminated by exhalation during breathing. The mucociliary clearance leading to the coughing up of sputum allows the more or less rapid elimination of the active ingredients. Once in the trachea, the active ingredients are swallowed and arrive in the digestive tract. Unlike oral administration, few drugs diffuse into the bloodstream due to the small quantity that reaches the pulmonary alveoli, which is the only point of passage to the blood (modified from [35]).

Figure 3
Elimination pathways of an inhaled drug

Some of the inhaled drugs are eliminated by exhalation during breathing. The mucociliary clearance leading to the coughing up of sputum allows the more or less rapid elimination of the active ingredients. Once in the trachea, the active ingredients are swallowed and arrive in the digestive tract. Unlike oral administration, few drugs diffuse into the bloodstream due to the small quantity that reaches the pulmonary alveoli, which is the only point of passage to the blood (modified from [35]).

Physicochemical constraints due to aerosol protocol

The physicochemical constraints associated with the aerosolization process are important. They may lead to a loss of the expected therapeutic effect (Figure 4). Not every active principle supports this mode of administration, hence the need for a formulation adapted to protect the active molecules. Moreover, depending on the nebulization system employed, the active principle will not react in the same way. For example, the dornase α, used to reduce viscosity of CF patient sputa, is degraded under the effect of heat when using an ultrasonic nebulizer [37]. Finally, research on the development of inhalation immunotherapy has shown that the antibodies poorly tolerate this mode of administration. An aggregation as well as chemical modifications were observed [38]. Once these physicochemical constraints have been overcome, the active principle must pass through various barriers mentioned below.

Extracellular factors limiting the therapeutic benefits of an aerosol

Figure 4
Extracellular factors limiting the therapeutic benefits of an aerosol

Inhaled drugs encounter different physicochemical barriers that can negatively impact their activity. The aerosolization itself is very restrictive for use of drugs. It will determine the size and charge of the aerosolized particles and therefore the deposit site. To interact with eukaryotic cells, particles must penetrate a more or less viscous mucus and limit the interactions with the components and elements trapped in the mucus. ASL contains bacteria, in planktonic form or organized in a biofilm, which can release enzymes capable of degrading the active principle. In addition, bacteria in the form of a biofilm are protected by a very robust exopolyssacharide matrix. Once in contact with eukaryotic cells, the active ingredient must pass through the plasma membrane.

Figure 4
Extracellular factors limiting the therapeutic benefits of an aerosol

Inhaled drugs encounter different physicochemical barriers that can negatively impact their activity. The aerosolization itself is very restrictive for use of drugs. It will determine the size and charge of the aerosolized particles and therefore the deposit site. To interact with eukaryotic cells, particles must penetrate a more or less viscous mucus and limit the interactions with the components and elements trapped in the mucus. ASL contains bacteria, in planktonic form or organized in a biofilm, which can release enzymes capable of degrading the active principle. In addition, bacteria in the form of a biofilm are protected by a very robust exopolyssacharide matrix. Once in contact with eukaryotic cells, the active ingredient must pass through the plasma membrane.

Extracellular barriers encountered by nanoparticles in the respiratory tract

Treatments targetting the inside of epithelial cells encounter several obstacles during their transit from the upper respiratory tract to target cells. In addition to the mechanical movements of respiration, many extracellular barriers are present in the lungs and are a hindrance for inhalation treatments (Figure 4) [17,39].

The mucus is the first barrier whose role is to purify the air breathed in by the individual by trapping the inhaled particles. The thickness of non-pathological mucus is between 5 and 10 μm [40]. It is replaced every 10–20 min on an average [40]. Due to its composition and rheology, mucus is a key barrier against efficient inhaled therapy [19]. This filtering structure permits the passage of particles having a size of approximately 100–200 nm [41]. In some obstructive diseases such as CF, the mucus is more viscous and the mesh is tighter [42]. In addition to its high mucin concentration, the mucus contains many other anionic molecules such as cell debris, DNA, or actin. The latter, because of their charge, can interact with inhaled drugs and limit their activity [43]. For non-viral gene therapy, this leads to a distinct increase in negative charge concentration which will break apart the nucleic acids/vector complexes.

A second surface liquid called a pulmonary surfactant is also present on the inner surface of the pulmonary alveoli and facilitates respiratory movements. It is secreted by type II pneumocytes. It reduces the air/liquid surface tension on the alveoli facilitating respiration. It also plays a role in immune defense. It consists of 90% lipids (mostly dipalmitoylphosphatidylcholine) and 10% proteins [44]. This surfactant can trap active principles. In newborns, usually premature infants, a deficiency in pulmonary surfactant results in respiratory distress. Similarly in adults, frequent alterations of the pulmonary surfactant are observed. They can occur as a result of drowning and/or acute respiratory distress syndrome. Different exogenous surfactants exist and are administered endotracheally, which is quite invasive [45].

An innate defense system called mucociliary clearance helps eliminate inhaled toxicants (pollutants, microbes etc.) [4648]. During inhalation, the particles are trapped in the mucus. The cilia present on the surface of the respiratory epithelium beat in a synchronized manner at a frequency of 1000–1500 beats per minute. This ciliary movement moves the mucus up to the trachea. The rate of upward movement of the mucus is between 5 and 20 mm/min. Once in the trachea, the mucus will be eliminated by the digestive tract or by expectoration. As previously stated, mucociliary clearance is a route of rapid elimination for inhaled drugs. It is therefore necessary that these therapeutical drugs must not remain blocked in the mucus which favors their elimination.

The development of high-throughput sequencing tools has demonstrated the presence of s pulmonary microbiota in the lower respiratory tract which had been long considered sterile, this includes healthy individuals [49]. This flora is present from an early age. It varies from one individual to another, depending on age and health status. Certain pathologies (CF, COPD, asthma) lead to an imbalance of this flora, favoring the progressive development of pathogens [50]. Bacteria responsible for lung infections produce enzymes capable of degrading certain drugs such as antibiotics.

The pulmonary microbiota comprises various bacterial species [49,5153]. Bacteria can grow planktonically or as biofilm. The passage from planktonic bacteria to bacteria in biofilm leads to an increase in tolerance to treatments [5456]. In the presence of a biofilm, the penetration of the active ingredient in the mucus is reduced due to the composition of the matrix formed, mainly of polysaccharides, proteins, nucleic acids, and lipids [57]. In a biofilm, the proximity of the bacteria and the presence of nucleic acids favor the dissemination of resistance by horizontal transmission of the genes. Finally, within a biofilm, part of the bacteria are dormant. This state of low active metabolism prevents the activity of certain antibacterial agents [58,59].

Clinical applications for aerosol formulations

In France and most of western industrial countries, several drugs received marketing authorization for administration by aerosolization, their function are diverse: bronchodilators, corticosteroids, antibiotics, antiparasitic, anti-allergic, mucolytic, antiplatelet, and nasal decongestant (Table 1).

Table 1
Example of inhaled drugs
Pharmacological classINNPathologyReferences
Bronchodilators Ipratropium bromide Asthma, COPD [130
 Terbutaline Asthma, COPD [131
 Salbumatol Asthma, COPD [132
Corticoids Budesodine Asthma [133
 Beclometasone Asthma [134
Anti-infective agents Tobramycin CF [135
 Colistimethate sodium CF [136
 Aztreonam CF [137
 Pentamidine Immunosuppressed [138
Mucolytics Deoxyribonuclease 1 CF [139
Antiplatelet agent Iloprost PAH [140
Anti-allergic Sodium cromoglycate Asthma [141
Anesthesic Lidocaine Asthma [142
Pharmacological classINNPathologyReferences
Bronchodilators Ipratropium bromide Asthma, COPD [130
 Terbutaline Asthma, COPD [131
 Salbumatol Asthma, COPD [132
Corticoids Budesodine Asthma [133
 Beclometasone Asthma [134
Anti-infective agents Tobramycin CF [135
 Colistimethate sodium CF [136
 Aztreonam CF [137
 Pentamidine Immunosuppressed [138
Mucolytics Deoxyribonuclease 1 CF [139
Antiplatelet agent Iloprost PAH [140
Anti-allergic Sodium cromoglycate Asthma [141
Anesthesic Lidocaine Asthma [142

Abbreviations: INN, international non-proprietary name; PAH, pulmonary arterial hypertension.

Several pathologies benefit from this mode of administration. Currently, the causes of morbidity and mortality of patients with CF (or COPD) are lung damage. In these pathologies, aerosolization is partly used for the administration of antibiotics (Tobi®, Bramitob® Tobramycin; Cayston® Aztreonam lysine; Promixin® Colistimethate sodium; Tobi® Podhaler™ Tobramycin; Colobreathe® Colistimethate sodium; Aeroquin® Levofloxacin) but also for bronchodilators and mucolytics (Bronchitol® Mannitol, Pulmozyme® Dornase α) [37].

On the other hand, this route of administration has also been used in viral or non-viral gene therapy [12,6064]. To date, clinical trials with viral vectors derived from adenovirus or associated adenovirus were disappointing and did not improve lung function. Alton and co-workers [12] conducted the first randomized clinical trial (phase IIb), as a double-blind (n=135), for non-viral gene therapy for CF (gene drug compared with placebo). The treatment was administered by aerosolization monthly for 1 year. A gain of 3.7% of the FEV1 was observed in treated patients. The results have been a proof of the feasibility of gene transfer by aerosolization with the absence of side effects.

Transfecting formulations with antibacterial effects for gene therapy

Potential benefits for gene delivery

The antibacterial activity of a gene transfer system could be beneficial for transfecting in an infected extracellular environment [20,65]. The benefits of such a combination of different activities are summarized in Figure 5.

Multifunctional synthetic vectors: an advantage for gene transfer under infectious conditions

Figure 5
Multifunctional synthetic vectors: an advantage for gene transfer under infectious conditions

The antibacterial activity of a gene transfer system would make it possible to transfect the eukaryotic cells in the presence of bacteria which impair the efficiency of the gene transfer. The production of toxins by bacteria and the induction of an inflammatory response leads to stress or even cell death. The antibacterial effect would eliminate the bacteria on the surface, promoting the transfection process and so the level of expression of the transgene.

Figure 5
Multifunctional synthetic vectors: an advantage for gene transfer under infectious conditions

The antibacterial activity of a gene transfer system would make it possible to transfect the eukaryotic cells in the presence of bacteria which impair the efficiency of the gene transfer. The production of toxins by bacteria and the induction of an inflammatory response leads to stress or even cell death. The antibacterial effect would eliminate the bacteria on the surface, promoting the transfection process and so the level of expression of the transgene.

Foremost, nucleic acids are fragile molecules that cannot tolerate aerosolization. The physicochemical constraints will induce a degradation of the nucleic acids which will be more or less important depending on their size [66,67]. The complexation of the nucleic acids by means of synthetic vectors is therefore required for this mode of administration. Moreover, this complexation will limit the degradation due to the presence of deoxyribonucleases in the extracellular matrix [21]. These enzymes are produced by bacteria such as Staphylococcus aureus. In an infected environment, the level of deoxyribonucleases is high. In addition, the formulations based on synthetic vectors are multimodular, which is to say that they can be adapted to the target environment by integrating several compounds enabling the possibility to cross the successive barriers. In example, pegylation (with PEG)) is a frequently used process to reduce surface charge and thus an easier penetration into the ASL [68]. Unlike the mucoadhesive agents which make it possible to increase the retention time of the active ingredient in the mucus, the PEG is a so-called mucopenetrating particle. A study on the delivery of an anti-inflammatory drug (dexamethasone) showed that PEG favored diffusion in the mucus and the release of the drug when compared with mucoadhesive particles such as poly(lactide-co-acid glycolide) (PLGA) [69].

Finally, the encapsulation is beneficial in order to potentiate the effects of the active molecules. Several active drugs (antibacterial, anticancer etc.) have been encapsulated by synthetic vectors. Alipour and co-workers [43] evaluated the antibacterial efficiency of two antibiotics (tobramycin or polymyxin B) encapsulated either by 1,2-dimyristoyl-sn-glycero-3-phosphocholine and cholesterol (DMPC:Chol, molar ratio: 1/2), or by 1,2-dipalmitoyl phosphatidylcholine and cholesterol (DPPC:Chol, molar ratio: 1/2). The antibacterial effect obtained on a strain of Pseudomonas aeruginosa, are far greater with the encapsulated form, even in the presence of polyanionic molecules (DNA, actin, lipopolysaccharides, lipoteichoic acids) frequently found in the sputum of CF patients. Similarly, Meers and co-workers [70] encapsulated amikacin (antibiotic) with a liposomal solution of DPPC:Chol (w/w: 2/1). They aerosolized the encapsulated formulation and the free form of the antibiotic in rats infected with P. aeruginosa. They found that the free form was ineffective in contrast with the encapsulated one. The lung concentration of bacteria in rat that benefited from the liposomal form was reduced. The aerosolization of the encapsulated form allowed a larger concentration of antibiotics to be present in the lungs for a longer amount of time, thereby limiting the emergence of bacterial resistance [70].

As we have seen, the presence of bacteria in the cellular environment can be harmful for gene transfer. This phenomenon can be accentuated in case of dysbiosis (an imbalance) of the bacterial flora leading to the appearance of infections. Growing bacteria is a very important barrier, which has long been neglected in the context of gene transfer applied to the respiratory tract. As mentioned above, bacteria produce toxins that can induce stress and/or cell death [71,72]. In addition, the infections are accompanied by strong inflammation. Inflammation induces the formation of reactive oxygen species which can lead to cell death [73]. All this will also contribute to limiting the expression of the transgene. The antibacterial activity of a transfecting formulation would eliminate bacteria localized in the cellular environment. Not only this elimination would promote access to eukaryotic cells in the presence of biofilm, it would also decrease the stress induced by the presence of bacteria in the cellular environment. Therefore, gene transfer could be carried out in a more favorable environment. Finally, expression of the transgene could further promote the eradication of infections. This is the case for CF, where the restoration of CFTR expression would induce a reduction in the risk of infection by the progressive fluidification of mucus through the restoration of ionic transports [7477].

The aim of our strategy is to transfer the antibacterial effect of the active principle to the vector itself so as to be able to transport other active principles (such as nucleic acids for example), which in parallel reduces the risks of side effects generated by drug interactions. In order to obtain formulations with antibacterial and transfecting properties, several options are available. Several antibiotics have been encapsulated by synthetic vectors which have shown transfection capability. However, the antibiotics, which usually find themselves stuck with the complexes, need to be released to be efficient. The combination of antibacterial molecules and nucleic acids encapsulated by synthetic vectors could allow the two activities to be obtained. In addition, some synthetic vectors, which will be described hereinafter, are endowed with their own antibacterial activity. This activity would make it possible not to use the antibiotics which can cause an appearance of bacterial resistance.

Antibiotics encapsulated by synthetic vectors

Attempts have been made to encapsulate antibiotics in order to decrease side effects since the 1980s [78,79]. Due to their fusion capability with plasma membranes and their capability of encapsulation, the synthetic vectors derived mainly from natural phospholipids have been used. These combinations have allowed the production of original formulations which will be described hereinafter.

Currently, two formulations of encapsulated antibiotics are used in Europe for pulmonary infections in aerosol delivery: TOBI® Podhaler™ (Novartis) and Arikace™ (Insmed) (Table 2). TOBI® Podhaler™ corresponds to the encapsulation of tobramycin (aminoside) by a cationic lipid, distearoyl phosphatidylcholine (DSPC). DSPC is used as a co-lipid for the formation of lipoplexes in the context of the delivery of interfering RNA [3,80,81]. This drug is prescribed for treating chronic pulmonary infections with P. aeruginosa in CF patients. Arikace™ is an aminoglycoside (amikacin) encapsulated by DPPC and cholesterol. DPPC is a natural lipid commonly used in gene transfer and has shown notable effects toward many different cell types but not for gene therapy in itself [82]. This drug has not received marketing authorization but is used clinically in a regulated context thanks to a transitional exemption. This encapsulated antibiotic can be delivered by aerosolization (eFlow® nebulizer) to CF patients whose pulmonary pathways are chronically infected with P. aeruginosa [70,83].

Table 2
Synthetic vectors used to encapsulate antibiotics
Encapsulated drugSynthetic vectors chemical structureReferences
Tobramycin  [81,143
Amikacin  [8
Encapsulated drugSynthetic vectors chemical structureReferences
Tobramycin  [81,143
Amikacin  [8

Other anti-infective agents are being evaluated clinically. Polymyxin is a polycationic antibiotic used to control Gram-negative infections. Its systemic administration induces significant side effects (nephrotoxicity, ototoxicity, and neuromuscular blockage). Several studies are searching for ways to encapsulate this antibiotic to limit its side effects and administer it by inhalation. The encapsulation of polymyxin B with DPPC showed better activity compared with the non-encapsulated form on a mouse pneumonia model and limits side effects [8486].

Pulmaquin™ and Lipoquin™ (Aradigm, Hayward, CA, U.S.A.) are the encapsulated forms of ciprofloxacin with 65.9 mg/ml of hydrogenated phosphatidylcholine (HSPC) and 27 mg/ml of cholesterol. These two forms of liposomal antibiotics are used to treat chronic P. aeruginosa infections in immunocompromised patients. Lipoquin™ is also prescribed for CF patients and is administered by aerosol with a jet nebulizer. The release kinetics of ciprofloxacin varies according to the formulation. However, the release of the antibiotic is slower with Pulmaquin™ [87].

Synthetic vectors with antibacterial effects

Some synthetic vectors are endowed with antibacterial and transfecting activities (Table 3).

Table 3
Example of synthetic vectors with an antibacterial activity
Synthetic vector familyChemical structureAntibacterial effectReferences
Antimicrobial peptide  Gram+ Gram– [88
Polymer  Gram+ Gram– [124
Aminoside derivative  Gram+ [98101
Sterol derivative cationic lipid  Gram+ Gram– [20,115
Lipophosphoramidate  Gram+ [21
Synthetic vector familyChemical structureAntibacterial effectReferences
Antimicrobial peptide  Gram+ Gram– [88
Polymer  Gram+ Gram– [124
Aminoside derivative  Gram+ [98101
Sterol derivative cationic lipid  Gram+ Gram– [20,115
Lipophosphoramidate  Gram+ [21

Antimicrobial peptides

Legendre and Szoka showed that antimicrobial peptides (gramicidin S, tyrocidin) with proved antibacterial activity, had a transfecting capability similar to that observed with cationic lipids [88]. These compounds have the ability to bind DNA by electrostatic interactions. Moreover, the fact that they are amphiphilic makes it possible to permeabilize the membranes [89,90]. These antimicrobial peptides act on Gram(+) and Gram(–) bacteria. The complexation of nucleic acids by antimicrobial peptides does not affect their antibacterial activity [91]. Their broad spectrum of activity makes antimicrobial peptides good candidates for antibacterial and transfecting formulations.

Cationics lipids inspired from antibiotics

Some families of antibiotics such as aminoglycosides have the ability to bind nucleic acids (DNA and RNA) [92]. This observed characteristic, essential to gene transfer agents for correct complexation, was used for the synthesis of novel cationic lipids. Some lipid derivatives’ polar heads incorporate an aminoside such as kanamycin (KanaChol) [93,94] or neamine [95], a neomycin fragment. The aminoglycoside polar head makes it possible to condense the nucleic acid constructs and their cholesteryl motif facilitates the entry into the eukaryotic cell. After evaluation of their transfecting activity post-deposit, these lipid derivatives have shown an interesting efficiency for gene transfer in various mammalian cell lines [94,96,97]. In parallel, these amphiphilic derivatives of antibiotics also exhibit an antibacterial activity on P. aeruginosa [98101].

Cationic polymers

On one hand, Wu and Hsu evaluated the cationic polymers’ (water-based cationic polyurethanes) antibacterial potency on Escherichia coli and S. aureus strains which has proved to be potent [102]. On the other hand, high transfection efficiencies were obtained on a renal cell line [102].

Poly-L-lysine is a polymer commonly used for gene transfer [5,68,103,104]. In 2013, Dubois and co-workers [105] studied the antibacterial activity of poly-L-lysine. They found that this polymer made it possible to kill the bacteria such as the P. aeruginosa and S. aureus species which are frequently isolated from sputum of CF patients [106].

Finally, PEI and its branched or histidinylated derivatives are heavily used for gene transfer. They showed a very good transfection activity [5,107,108] on post-aerosolization on murine and sheep models as well [109112]. In addition to this gene transfer capability, this family of synthetic vectors exhibited antibacterial (Gram(+) and Gram(–)) and antifungal activity post-deposit [113,114]. No studies evaluated the antibacterial potency of post-aerosolization PEI.

Monocationic lipids derived from phospholipids

Similarly, other molecules not derived from antibiotics and which bind to DNA, such as spermine, have also shown transfection activity as well as an antibacterial effect on Gram(+) bacteria (Bacillus subtilis) and Gram (–) bacteria (E. coli) [115].

Fein and co-workers [20] are interested in the antibacterial and transfection properties of two steroid-derived cationic lipids called dexamethasone spermine (DS) and disubstituted spermine (D2S). These two compounds have been studied individually and as co-formulation. The evaluation of the various lipoplexes by direct deposit in the extracellular medium, revealed a good transfection activity on cell line A549 (epithelial cells derived from pulmonary carcinoma). Antimicrobial activity on Gram(–) bacteria (E. coli MG1655 and P. aeruginosa PAO1) and Gram(+) B. subtilis was obtained with D2S at low concentrations (5 μM). Given the chemical structure of D2S, they hypothesize that the antibacterial activity is due to the amphiphilic structure resembling antimicrobial peptides such as cathelicidin LL-37 which would favor destabilization of the bacterial membrane [20].

Subsequently, novel cationic derivatives of steroids containing other glucocorticoids (flumetasone, budesonide, and beclometasone) have been developed. Anti-inflammatory, antibacterial, transfectant, and cytotoxic activities were then evaluated [116]. These compounds showed antibacterial effects (a few µM depending on strain) on different strains of P. aeruginosa and methycillin-resistant S. aureus (Xen30). The transfection capability was evaluated in parallel by direct deposit on BAECs and A549 cell lines. Some compounds have levels of transfection similar to those obtained with Lipofectamine® 2000, a commercial transfer agent which has no antibacterial effect (Thermo Fischer Scientific).

Dodecyltrimethylammonium bromide (DODAB) can complex the DNA and thus allow the gene transfer [117,118]. Different studies have shown that quaternary ammonium compounds have antibacterial and antifungal activities [119121]. Some geminis with two quaternary ammonium heads have shown good transfection efficiency due to their strong DNA interaction [122,123]. In addition, they exhibit antibacterial activity on Gram(+) bacteria (E. coli and P. aeruginosa) [124].

In 2013, our study confirmed the presence of antibacterial activity on some synthetic vectors originally designed for gene transfer [21]. After structure-activity analysis of a series of cationic lipophosphoramidate, it has been found that the nature of the polar head and aliphatic chains are the key elements of antibacterial potency. Contrary to trimethylammonium lipophosphoramidates, only a few cationic lipids with a trimethylarsonium or trimethylphosphonium polar head exhibit an antibacterial activity on different strains of S. aureus. The best antibacterial activity was obtained with arseno compounds. Furthermore, the structure and length of the aliphatic chains would affect the antibacterial activity. The degree of unsaturation and the length of the aliphatic chain permit the improvement of the antibacterial activity of trimethylarsonium lipophosphoramidate. This antibacterial activity was observed for relatively low concentrations, which are close to those used for the transfection of eukaryotic cells. This is an important point to simultaneously study both activities. To explore this hypothesis, liquid co-cultures of bacteria and human bronchial epithelial cells were used. In the present study, it was shown that the antibacterial activity of the cationic lipid makes it possible to obtain, in the presence of a bacterial infection, a transfection activity equivalent to that observed in the absence of bacteria.

Synthetic vector based formulations

To broaden the spectrum of activity, previously studied silver compounds [125] were introduced into the formulation and experiments showed that the antibacterial activity was extended to Gram(–), which are problematic in CF, and that this activity was retained post-aerosolization (currently being submitted). To our knowledge, only one other study has combined molecules of different activities in order to obtain multifunctional transfer systems. Peng and co-workers [126] combined a gold nanoparticle (AuP) with an antimicrobial peptide (PEP ‘peptide sequence from lactoferrin’). This combination allowed Peng and co-workers [126] to efficiently transfect mesenchymal stem cells. The gold nanoparticles are known for their transfection power [127] as well as for their antibacterial activity on Gram(+) and Gram(–) bacteria [128,129]. However, these activities have not been tested by aerosolization.

Conclusion

Antibiotics encapsulated in a formulation must be released in order to be available and come into contact with bacteria. Transferring the antibacterial effect directly to the vector would allow a more immediate effect. Multimodular vectors are a major asset to overcome the different barriers encountered and to act according to therapeutic targets, which are, not only the bacteria for the antibacterial effect at the extracellular level, but also the nucleus for the gene transfer. Besides gene transfer, many other applications such as administration of anticancer drugs, anti-inflammatory reagents, or various other molecules such as insulin can be considered. The formulations will be adapted to the constraints related to the inhaled administration and its environment. Finally, in order to combat the rapid increase in bacterial resistance, the antibacterial activity of the vector coupled with the antibacterial activity of the encapsulated antibiotic would allow the introduction of bi-antibiotic therapy. Thus, the targets will be more numerous and will allow the better treatment of the infections that are still difficult to treat today, such as nosocomial diseases which can infect immunosuppressed patients.

We thank Prof Pierre Lehn for his constant scientific support.

Competing interests

The authors declare that there are no competing interests associated with the manuscript.

Funding

This work was supported by the ‘Association Française contre les Myopathies’ (AFM, Evry, France) [grant number XXXX]; the ‘Vaincre La Mucoviscidose’ (Paris, France) [grant number XXXX]; the ‘Association de transfusion sanguine et de biogénétique Gaétan Saleün’ (Brest, France) [grant number XXXX]; the ‘Région Bretagne’ [grant number XXXX]; the Brest Métropôle [grant number XXXX]; and the Mr Michel Caugant [grant number XXXX].

Abbreviations

     
  • ASL

    airway surface liquid

  •  
  • BAEc

    Bovine Aortic Endothelial cells

  •  
  • CF

    cystic fibrosis

  •  
  • CFTR

    cystic Fibrosis Transmembrane conductane Regulator

  •  
  • COPD

    chronic obstructive pulmonary disease

  •  
  • DPPC

    1,2-dipalmitoyl phosphatidylcholine

  •  
  • DSPC

    distearoyl phosphatidylcholine

  •  
  • D2S

    disubstituted spermine

  •  
  • LL-37

    cathelcidin antimicrobial peptide

  •  
  • FEV1

    forced expiratory volume in 1 s

  •  
  • F508del

    deletion of three nucleotides (position 508) of cftr gene

  •  
  • PCL

    periciliary layer

  •  
  • PEI

    polyethyleneimine

  •  
  • PEP

    Peptide sequence from lactoferrin

References

1
Felgner
P.L.
,
Gadek
T.R.
,
Holm
M.
,
Roman
R.
,
Chan
H.W.
,
Wenz
M.
et al
(
1987
)
Lipofection: a highly efficient, lipid-mediated DNA-transfection procedure
.
Proc. Natl. Acad. Sci. U.S.A.
84
,
7413
7417
2
Ibraheem
D.
,
Elaissari
A.
and
Fessi
H.
(
2014
)
Gene therapy and DNA delivery systems
.
Int. J. Pharm.
459
,
70
83
3
Yin
H.
,
Kanasty
R.L.
,
Eltoukhy
A.A.
,
Vegas
A.J.
,
Dorkin
J.R.
and
Anderson
D.G.
(
2014
)
Non-viral vectors for gene-based therapy
.
Nat. Rev. Genet.
15
,
541
555
4
Mintzer
M.A.
and
Simanek
E.E.
(
2009
)
Nonviral vectors for gene delivery
.
Chem. Rev.
109
,
259
302
5
Li
L.
,
Wei
Y.
and
Gong
C.
(
2015
)
Polymeric nanocarriers for non-viral gene delivery
.
J. Biomed. Nanotechnol.
11
,
739
770
6
Oliveira
C.
,
Ribeiro
A.J.
,
Veiga
F.
and
Silveira
I.
(
2016
)
Recent advances in nucleic acid-based delivery: from bench to clinical trials in genetic diseases
.
J. Biomed. Nanotechnol.
12
,
841
862
7
Wu
G.Y.
and
Wu
C.H.
(
1987
)
Receptor-mediated in vitro gene transformation by a soluble DNA carrier system
.
J. Biol. Chem.
262
,
4429
4432
8
Boussif
O.
,
Lezoualc’h
F.
,
Zanta
M.A.
,
Mergny
M.D.
,
Scherman
D.
,
Demeneix
B.
et al
(
1995
)
A versatile vector for gene and oligonucleotide transfer into cells in culture and in vivo: polyethylenimine
.
Proc. Natl. Acad. Sci. U.S.A.
92
,
7297
7301
9
Chaplot
S.P.
and
Rupenthal
I.D.
(
2014
)
Dendrimers for gene delivery–a potential approach for ocular therapy?
J. Pharm. Pharmacol.
66
,
542
556
10
Mansouri
S.
,
Lavigne
P.
,
Corsi
K.
,
Benderdour
M.
,
Beaumont
E.
and
Fernandes
J.C.
(
2004
)
Chitosan-DNA nanoparticles as non-viral vectors in gene therapy: strategies to improve transfection efficacy
.
Eur. J. Pharm. Biopharm.
57
,
1
8
11
Montier
T.
,
Benvegnu
T.
,
Jaffrès
P.-A.
,
Yaouanc
J.-J.
and
Lehn
P.
(
2008
)
Progress in cationic lipid-mediated gene transfection: a series of bio-inspired lipids as an example
.
Curr. Gene Ther.
8
,
296
312
12
Alton
E.W.F.W.x
,
Armstrong
D.K.
,
Ashby
D.
,
Bayfield
K.J.
,
Bilton
D.
,
Bloomfield
E.V.
et al
(
2015
)
Repeated nebulisation of non-viral CFTR gene therapy in patients with cystic fibrosis: a randomised, double-blind, placebo-controlled, phase 2b trial
.
Lancet Respir. Med.
3
,
684
691
13
Kitson
C.
,
Angel
B.
,
Judd
D.
,
Rothery
S.
,
Severs
N.J.
,
Dewar
A.
et al
(
1999
)
The extra- and intracellular barriers to lipid and adenovirus-mediated pulmonary gene transfer in native sheep airway epithelium
.
Gene Ther.
6
,
534
546
14
Lechardeur
D.
and
Lukacs
G.L.
(
2002
)
Intracellular barriers to non-viral gene transfer
.
Curr. Gene Ther.
2
,
183
194
15
Gottfried
L.F.
and
Dean
D.A.
(
2013
)
Extracellular and intracellular barriers to non-viral gene transfer.
16
Montier
T.
,
Delépine
P.
,
Pichon
C.
,
Férec
C.
,
Porteous
D.J.
and
Midoux
P.
(
2004
)
Non-viral vectors in cystic fibrosis gene therapy: progress and challenges
.
Trends Biotechnol.
22
,
586
592
17
Sanders
N.
,
Rudolph
C.
,
Braeckmans
K.
,
De Smedt
S.C.
and
Demeester
J.
(
2009
)
Extracellular barriers in respiratory gene therapy
.
Adv. Drug Deliv. Rev.
61
,
115
127
18
Schuster
B.S.
,
Kim
A.J.
,
Kays
J.C.
,
Kanzawa
M.M.
,
Guggino
W.B.
,
Boyle
M.P.
et al
(
2014
)
Overcoming the cystic fibrosis sputum barrier to leading adeno-associated virus gene therapy vectors
.
Mol. Ther.
22
,
1484
1493
19
Duncan
G.A.
,
Jung
J.
,
Hanes
J.
and
Suk
J.S.
(
2016
)
The mucus barrier to inhaled gene therapy
.
Mol. Ther.
24
,
2043
2053
20
Fein
D.E.
,
Bucki
R.
,
Byfield
F.
,
Leszczynska
K.
,
Janmey
P.A.
and
Diamond
S.L.
(
2010
)
Novel cationic lipids with enhanced gene delivery and antimicrobial activity
.
Mol. Pharmacol.
78
,
402
410
21
Le Gall
T.
,
Berchel
M.
,
Le Hir
S.
,
Fraix
A.
,
Salaün
J.Y.
,
Férec
C.
et al
(
2013
)
Arsonium-containing lipophosphoramides, poly-functional nano-carriers for simultaneous antibacterial action and eukaryotic cell transfection
.
Adv. Healthc. Mater.
2
,
1513
1524
22
Griesenbach
U.
,
McLachlan
G.
,
Owaki
T.
,
Somerton
L.
,
Shu
T.
,
Baker
A.
et al
(
2011
)
Validation of recombinant Sendai virus in a non-natural host model
.
Gene Ther.
18
,
182
188
23
Hida
K.
,
Lai
S.K.
,
Suk
J.S.
,
Won
S.Y.
,
Boyle
M.P.
and
Hanes
J.
(
2011
)
Common gene therapy viral vectors do not efficiently penetrate sputum from cystic fibrosis patients
.
PLoS ONE
6
,
e19919
24
Button
B.
,
Cai
L.-H.
,
Ehre
C.
,
Kesimer
M.
,
Hill
D.B.
,
Sheehan
J.K.
et al
(
2012
)
A periciliary brush promotes the lung health by separating the mucus layer from airway epithelia
.
Science
337
,
937
941
25
Lai
S.K.
,
Wang
Y.-Y.
,
Wirtz
D.
and
Hanes
J.
(
2009
)
Micro- and macrorheology of mucus
.
Adv. Drug Deliv. Rev.
61
,
86
100
26
Tarran
R.
,
Loewen
M.E.
,
Paradiso
A.M.
,
Olsen
J.C.
,
Gray
M.A.
,
Argent
B.E.
et al
(
2002
)
Regulation of murine airway surface liquid volume by CFTR and Ca2+-activated Cl- conductances
.
J. Gen. Physiol.
120
,
407
418
27
Boucher
R.C.
(
2004
)
New concepts of the pathogenesis of cystic fibrosis lung disease
.
Eur. Respir. J.
23
,
146
158
28
Munkholm
M.
and
Mortensen
J.
(
2014
)
Mucociliary clearance: pathophysiological aspects
.
Clin. Physiol. Funct. Imaging
34
,
171
177
29
Davies
L.A.
,
Nunez-Alonso
G.A.
,
McLachlan
G.
,
Hyde
S.C.
and
Gill
D.R.
(
2014
)
Aerosol delivery of DNA/liposomes to the lung for cystic fibrosis gene therapy
.
Hum. Gene Ther. Clin. Dev.
25
,
97
107
30
Yhee
J.Y.
,
Im
J.
and
Nho
R.S.
(
2016
)
Advanced therapeutic strategies for chronic lung disease using nanoparticle-based drug delivery
.
J. Clin. Med.
5
, DOI:,
31
Resnier
P.
,
Mottais
A.
,
Sibiril
Y.
,
Gall
T.L.
and
Montier
T.
(
2016
)
Challenges and successes using nanomedicines for aerosol delivery to the airways
.
Curr. Gene Ther.
16
,
34
46
32
Becquemont
L.
(
2017
)
Maladie de Gaucher de type 1 (CYP2D6-éliglustat)
.
Thérapie
72
,
319
322
33
Saleh
P.
,
Abbasalizadeh
S.
,
Rezaeian
S.
,
Naghavi-Behzad
M.
,
Piri
R.
and
Pourfeizi
H.H.
(
2016
)
Gentamicin-mediated ototoxicity and nephrotoxicity: a clinical trial study
.
Niger. Med. J.
57
,
347
352
34
Murray
M.P.
,
Govan
J.R.W.
,
Doherty
C.J.
,
Simpson
A.J.
,
Wilkinson
T.S.
,
Chalmers
J.D.
et al
(
2011
)
A randomized controlled trial of nebulized gentamicin in non-cystic fibrosis bronchiectasis
.
Am. J. Respir. Crit. Care Med.
183
,
491
499
35
Kuzmov
A.
and
Minko
T.
(
2015
)
Nanotechnology approaches for inhalation treatment of lung diseases
.
J. Control. Release
219
,
500
518
36
Weers
J.
,
Metzheiser
B.
,
Taylor
G.
,
Warren
S.
,
Meers
P.
and
Perkins
W.R.
(
2009
)
A gamma scintigraphy study to investigate lung deposition and clearance of inhaled amikacin-loaded liposomes in healthy male volunteers
.
J. Aerosol Med. Pulm. Drug Deliv.
22
,
131
138
37
Dubus
J.-C.
and
Ravilly
S.
(
2008
)
Inhaled therapies in cystic fibrosis
.
Rev. Mal. Respir.
25
,
989
998
38
Respaud
R.
,
Vecellio
L.
,
Diot
P.
and
Heuzé-Vourc’h
N.
(
2015
)
Nebulization as a delivery method for mAbs in respiratory diseases
.
Expert Opin. Drug Deliv.
12
,
1027
1039
39
d’Angelo
I.
,
Conte
C.
,
La Rotonda
M.I.
,
Miro
A.
,
Quaglia
F.
and
Ungaro
F.
(
2014
)
Improving the efficacy of inhaled drugs in cystic fibrosis: challenges and emerging drug delivery strategies
.
Adv. Drug Deliv. Rev.
75
,
92
111
40
Lai
S.K.
,
Wang
Y.-Y.
and
Hanes
J.
(
2009
)
Mucus-penetrating nanoparticles for drug and gene delivery to mucosal tissues
.
Adv. Drug Deliv. Rev.
61
,
158
171
41
Schuster
B.S.
,
Suk
J.S.
,
Woodworth
G.F.
and
Hanes
J.
(
2013
)
Nanoparticle diffusion in respiratory mucus from humans without lung disease
.
Biomaterials
34
,
3439
3446
42
Kim
N.
,
Duncan
G.A.
,
Hanes
J.
and
Suk
J.S.
(
2016
)
Barriers to inhaled gene therapy of obstructive lung diseases: a review
.
J. Control. Release
240
,
465
488
43
Alipour
M.
,
Suntres
Z.E.
,
Halwani
M.
,
Azghani
A.O.
and
Omri
A.
(
2009
)
Activity and interactions of liposomal antibiotics in presence of polyanions and sputum of patients with cystic fibrosis
.
PLoS ONE
4
,
e5724
44
Hidalgo
A.
,
Cruz
A.
and
Pérez-Gil
J.
(
2017
)
Pulmonary surfactant and nanocarriers: toxicity versus combined nanomedical applications
.
Biochim. Biophys. Acta
1859
,
1740
1748
45
Speer
C.P.
,
Sweet
D.G.
and
Halliday
H.L.
(
2013
)
Surfactant therapy: past, present and future
.
Early Hum. Dev.
89
(
Suppl. 1
),
S22
S24
46
Knowles
M.R.
and
Boucher
R.C.
(
2002
)
Mucus clearance as a primary innate defense mechanism for mammalian airways
.
J. Clin. Invest.
109
,
571
577
47
Button
B.M.
and
Button
B.
(
2013
)
Structure and function of the mucus clearance system of the lung
.
Cold Spring Harb. Perspect. Med.
3
,
48
Bustamante-Marin
X.M.
and
Ostrowski
L.E.
(
2017
)
Cilia and mucociliary clearance
.
Cold Spring Harb. Perspect. Biol.
9
,
a028241
49
Faner
R.
,
Sibila
O.
,
Agustí
A.
,
Bernasconi
E.
,
Chalmers
J.D.
,
Huffnagle
G.B.
et al
(
2017
)
The microbiome in respiratory medicine: current challenges and future perspectives
.
Eur. Respir. J.
49
,
50
Marsland
B.J.
and
Gollwitzer
E.S.
(
2014
)
Host-microorganism interactions in lung diseases
.
Nat. Rev. Immunol.
14
,
827
835
51
Morris
A.
,
Beck
J.M.
,
Schloss
P.D.
,
Campbell
T.B.
,
Crothers
K.
,
Curtis
J.L.
et al
(
2013
)
Comparison of the respiratory microbiome in healthy nonsmokers and smokers
.
Am. J. Respir. Crit. Care Med.
187
,
1067
1075
52
Sze
M.A.
,
Hogg
J.C.
and
Sin
D.D.
(
2014
)
Bacterial microbiome of lungs in COPD
.
Int. J. Chron. Obstruct. Pulmon. Dis.
9
,
229
238
53
Hoppe
J.E.
and
Zemanick
E.T.
(
2017
)
Lessons from the lower airway microbiome in early CF
.
Thorax
,
54
Olson
M.E.
,
Ceri
H.
,
Morck
D.W.
,
Buret
A.G.
and
Read
R.R.
(
2002
)
Biofilm bacteria: formation and comparative susceptibility to antibiotics
.
Can. J. Vet. Res.
66
,
86
92
55
Ehsan
Z.
and
Clancy
J.P.
(
2015
)
Management of Pseudomonas aeruginosa infection in cystic fibrosis patients using inhaled antibiotics with a focus on nebulized liposomal amikacin
.
Future Microbiol.
10
,
1901
1912
56
Rukavina
Z.
and
Vanić
Ž.
(
2016
)
Current trends in development of liposomes for targeting bacterial biofilms
.
Pharmaceutics
8
,
57
Ciofu
O.
,
Tolker-Nielsen
T.
,
Jensen
P.Ø
,
Wang
H.
and
Høiby
N.
(
2015
)
Antimicrobial resistance, respiratory tract infections and role of biofilms in lung infections in cystic fibrosis patients
.
Adv. Drug Deliv. Rev.
85
,
7
23
58
Walters
M.C.
,
Roe
F.
,
Bugnicourt
A.
,
Franklin
M.J.
and
Stewart
P.S.
(
2003
)
Contributions of antibiotic penetration, oxygen limitation, and low metabolic activity to tolerance of Pseudomonas aeruginosa biofilms to ciprofloxacin and tobramycin
.
Antimicrob. Agents Chemother.
47
,
317
323
59
Lewis
K.
(
2008
)
Multidrug tolerance of biofilms and persister cells
.
Curr. Top. Microbiol. Immunol.
322
,
107
131
60
Porteous
D.J.
,
Dorin
J.R.
,
McLachlan
G.
,
Davidson-Smith
H.
,
Davidson
H.
,
Stevenson
B.J.
et al
(
1997
)
Evidence for safety and efficacy of DOTAP cationic liposome mediated CFTR gene transfer to the nasal epithelium of patients with cystic fibrosis
.
Gene Ther.
4
,
210
218
61
Bellon
G.
,
Michel-Calemard
L.
,
Thouvenot
D.
,
Jagneaux
V.
,
Poitevin
F.
,
Malcus
C.
et al
(
1997
)
Aerosol administration of a recombinant adenovirus expressing CFTR to cystic fibrosis patients: a phase I clinical trial
.
Hum. Gene Ther.
8
,
15
25
62
Perricone
M.A.
,
Morris
J.E.
,
Pavelka
K.
,
Plog
M.S.
,
O’Sullivan
B.P.
,
Joseph
P.M.
et al
(
2001
)
Aerosol and lobar administration of a recombinant adenovirus to individuals with cystic fibrosis. II. Transfection efficiency in airway epithelium
.
Hum. Gene Ther.
12
,
1383
1394
63
Aitken
M.L.
,
Moss
R.B.
,
Waltz
D.A.
,
Dovey
M.E.
,
Tonelli
M.R.
,
McNamara
S.C.
et al
(
2001
)
A phase I study of aerosolized administration of tgAAVCF to cystic fibrosis subjects with mild lung disease
.
Hum. Gene Ther.
12
,
1907
1916
64
Moss
R.B.
,
Rodman
D.
,
Spencer
L.T.
,
Aitken
M.L.
,
Zeitlin
P.L.
,
Waltz
D.
et al
(
2004
)
Repeated adeno-associated virus serotype 2 aerosol-mediated cystic fibrosis transmembrane regulator gene transfer to the lungs of patients with cystic fibrosis: a multicenter, double-blind, placebo-controlled trial
.
Chest
125
,
509
521
65
Myint
M.
,
Limberis
M.P.
,
Bell
P.
,
Somanathan
S.
,
Haczku
A.
,
Wilson
J.M.
et al
(
2014
)
In vivo evaluation of adeno-associated virus gene transfer in airways of mice with acute or chronic respiratory infection
.
Hum. Gene Ther.
25
,
966
976
66
Lentz
Y.K.
,
Worden
L.R.
,
Anchordoquy
T.J.
and
Lengsfeld
C.S.
(
2005
)
Effect of jet nebulization on DNA: identifying the dominant degradation mechanism and mitigation methods
.
J. Aerosol Sci.
36
,
973
990
67
Catanese
D.J.
,
Fogg
J.M.
,
Schrock
D.E.
,
Gilbert
B.E.
and
Zechiedrich
L.
(
2012
)
Supercoiled Minivector DNA resists shear forces associated with gene therapy delivery
.
Gene Ther.
19
,
94
100
68
Ryan
G.M.
,
Kaminskas
L.M.
,
Kelly
B.D.
,
Owen
D.J.
,
McIntosh
M.P.
and
Porter
C.J.H.
(
2013
)
Pulmonary administration of PEGylated polylysine dendrimers: absorption from the lung versus retention within the lung is highly size-dependent
.
Mol. Pharm.
10
,
2986
2995
69
Schneider
C.S.
,
Xu
Q.
,
Boylan
N.J.
,
Chisholm
J.
,
Tang
B.C.
,
Schuster
B.S.
et al
(
2017
)
Nanoparticles that do not adhere to mucus provide uniform and long-lasting drug delivery to airways following inhalation
.
Sci. Adv.
3
,
e1601556
70
Meers
P.
,
Neville
M.
,
Malinin
V.
,
Scotto
A.W.
,
Sardaryan
G.
,
Kurumunda
R.
et al
(
2008
)
Biofilm penetration, triggered release and in vivo activity of inhaled liposomal amikacin in chronic Pseudomonas aeruginosa lung infections
.
J. Antimicrob. Chemother.
61
,
859
868
71
Rada
B.
and
Leto
T.L.
(
2013
)
Pyocyanin effects on respiratory epithelium: relevance in Pseudomonas aeruginosa airway infections
.
Trends Microbiol.
21
,
73
81
72
Adam
D.
,
Perotin
J.-M.
,
Lebargy
F.
,
Birembaut
P.
,
Deslée
G.
and
Coraux
C.
(
2014
)
Regeneration of airway epithelium
.
Rev. Mal. Respir.
31
,
300
311
73
Rosanna
D.P.
and
Salvatore
C.
(
2012
)
Reactive oxygen species, inflammation, and lung diseases
.
Curr. Pharm. Des.
18
,
3889
3900
74
Johnson
L.G.
,
Olsen
J.C.
,
Sarkadi
B.
,
Moore
K.L.
,
Swanstrom
R.
and
Boucher
R.C.
(
1992
)
Efficiency of gene transfer for restoration of normal airway epithelial function in cystic fibrosis
.
Nat. Genet.
2
,
21
25
75
Davies
J.C.
,
Stern
M.
,
Dewar
A.
,
Caplen
N.J.
,
Munkonge
F.M.
,
Pitt
T.
et al
(
1997
)
CFTR gene transfer reduces the binding of Pseudomonas aeruginosa to cystic fibrosis respiratory epithelium
.
Am. J. Respir. Cell Mol. Biol.
16
,
657
663
76
Biffi
A.
,
Sersale
G.
,
Cassetti
A.
,
Villa
A.
,
Bordignon
C.
,
Assael
B.M.
et al
(
1999
)
Restoration of bacterial killing activity of human respiratory cystic fibrosis cells through cationic vector-mediated cystic fibrosis transmembrane conductance regulator gene transfer
.
Hum. Gene Ther.
10
,
1923
1930
77
Hisert
K.B.
,
Heltshe
S.L.
,
Pope
C.
,
Jorth
P.
,
Wu
X.
,
Edwards
R.M.
et al
(
2017
)
Restoring CFTR function reduces airway bacteria and inflammation in people with cystic fibrosis and chronic lung infections
.
Am. J. Respir. Crit. Care Med.
,
78
Lagacé
J.
,
Dubreuil
M.
and
Montplaisir
S.
(
1991
)
Liposome-encapsulated antibiotics: preparation, drug release and antimicrobial activity against Pseudomonas aeruginosa
.
J. Microencapsul.
8
,
53
61
79
Omri
A.
,
Beaulac
C.
,
Bouhajib
M.
,
Montplaisir
S.
,
Sharkawi
M.
and
Lagacé
J.
(
1994
)
Pulmonary retention of free and liposome-encapsulated tobramycin after intratracheal administration in uninfected rats and rats infected with Pseudomonas aeruginosa
.
Antimicrob. Agents Chemother.
38
,
1090
1095
80
Zimmermann
T.S.
,
Lee
A.C.H.
,
Akinc
A.
,
Bramlage
B.
,
Bumcrot
D.
,
Fedoruk
M.N.
et al
(
2006
)
RNAi-mediated gene silencing in non-human primates
.
Nature
441
,
111
114
81
Kulkarni
J.A.
,
Myhre
J.L.
,
Chen
S.
,
Tam
Y.Y.C.
,
Danescu
A.
,
Richman
J.M.
et al
(
2016
)
Design of lipid nanoparticles for in vitro and in vivo delivery of plasmid DNA
.
Nanomed. Nanotech. Biol. Med.
,
82
Manosroi
A.
,
Thathang
K.
,
Manosroi
J.
,
Werner
R.G.
,
Schubert
R.
and
Peschka-Süss
R.
(
2009
)
Expression of luciferase plasmid (pCMVLuc) entrapped in DPPC/cholesterol/DDAB liposomes in HeLa cell lines
.
J. Liposome Res.
19
,
131
140
83
Clancy
J.P.
,
Dupont
L.
,
Konstan
M.W.
,
Billings
J.
,
Fustik
S.
,
Goss
C.H.
et al
(
2013
)
Phase II studies of nebulised Arikace in CF patients with Pseudomonas aeruginosa infection
.
Thorax
68
,
818
825
84
Omri
A.
,
Suntres
Z.E.
and
Shek
P.N.
(
2002
)
Enhanced activity of liposomal polymyxin B against Pseudomonas aeruginosa in a rat model of lung infection
.
Biochem. Pharmacol.
64
,
1407
1413
85
Alipour
M.
,
Halwani
M.
,
Omri
A.
and
Suntres
Z.E.
(
2008
)
Antimicrobial effectiveness of liposomal polymyxin B against resistant Gram-negative bacterial strains
.
Int. J. Pharm.
355
,
293
298
86
He
J.
,
Abdelraouf
K.
,
Ledesma
K.R.
,
Chow
D.S.-L.
and
Tam
V.H.
(
2013
)
Pharmacokinetics and efficacy of liposomal polymyxin B in a murine pneumonia model
.
Int. J. Antimicrob. Agents
42
,
559
564
87
Cipolla
D.
,
Blanchard
J.
and
Gonda
I.
(
2016
)
Development of liposomal ciprofloxacin to treat lung infections
.
Pharmaceutics
8
,
88
Legendre
J.Y.
and
Szoka
F.C.
(
1993
)
Cyclic amphipathic peptide-DNA complexes mediate high-efficiency transfection of adherent mammalian cells
.
Proc. Natl. Acad. Sci. U.S.A.
90
,
893
897
89
Kichler
A.
,
Bechinger
B.
and
Danos
O.
(
2003
)
Antimicrobial peptides as efficient DNA vectors
.
Méd. Sci.
19
,
1046
1047
90
Kichler
A.
,
Leborgne
C.
,
Savage
P.B.
and
Danos
O.
(
2005
)
Cationic steroid antibiotics demonstrate DNA delivery properties
.
J. Control. Release
107
,
174
182
91
Kichler
A.
,
Leborgne
C.
,
März
J.
,
Danos
O.
and
Bechinger
B.
(
2003
)
Histidine-rich amphipathic peptide antibiotics promote efficient delivery of DNA into mammalian cells
.
Proc. Natl. Acad. Sci. U.S.A.
100
,
1564
1568
92
Walter
F.
,
Vicens
Q.
and
Westhof
E.
(
1999
)
Aminoglycoside-RNA interactions
.
Curr. Opin. Chem. Biol.
3
,
694
704
93
Belmont
P.
,
Aissaoui
A.
,
Hauchecorne
M.
,
Oudrhiri
N.
,
Petit
L.
,
Vigneron
J.-P.
et al
(
2002
)
Aminoglycoside-derived cationic lipids as efficient vectors for gene transfection in vitro and in vivo
.
J. Gene Med.
4
,
517
526
94
Sainlos
M.
,
Hauchecorne
M.
,
Oudrhiri
N.
,
Zertal-Zidani
S.
,
Aissaoui
A.
,
Vigneron
J.-P.
et al
(
2005
)
Kanamycin A-derived cationic lipids as vectors for gene transfection
.
Chembiochem
6
,
1023
1033
95
Le Gall
T.
,
Baussanne
I.
,
Halder
S.
,
Carmoy
N.
,
Montier
T.
,
Lehn
P.
et al
(
2009
)
Synthesis and transfection properties of a series of lipidic neamine derivatives
.
Bioconjug. Chem.
20
,
2032
2046
96
Desigaux
L.
,
Sainlos
M.
,
Lambert
O.
,
Chevre
R.
,
Letrou-Bonneval
E.
,
Vigneron
J.-P.
et al
(
2007
)
Self-assembled lamellar complexes of siRNA with lipidic aminoglycoside derivatives promote efficient siRNA delivery and interference
.
Proc. Natl. Acad. Sci. U.S.A.
104
,
16534
16539
97
Mével
M.
,
Sainlos
M.
,
Chatin
B.
,
Oudrhiri
N.
,
Hauchecorne
M.
,
Lambert
O.
et al
(
2012
)
Paromomycin and neomycin B derived cationic lipids: synthesis and transfection studies
.
J. Control. Release
158
,
461
469
98
Baussanne
I.
,
Bussière
A.
,
Halder
S.
,
Ganem-Elbaz
C.
,
Ouberai
M.
,
Riou
M.
et al
(
2010
)
Synthesis and antimicrobial evaluation of amphiphilic neamine derivatives
.
J. Med. Chem.
53
,
119
127
99
Bera
S.
,
Zhanel
G.G.
and
Schweizer
F.
(
2010
)
Antibacterial activity of guanidinylated neomycin B- and kanamycin A-derived amphiphilic lipid conjugates
.
J. Antimicrob. Chemother.
65
,
1224
1227
100
Ouberai
M.
,
El Garch
F.
,
Bussiere
A.
,
Riou
M.
,
Alsteens
D.
,
Lins
L.
et al
(
2011
)
The Pseudomonas aeruginosa membranes: a target for a new amphiphilic aminoglycoside derivative?
Biochim. Biophys. Acta
1808
,
1716
1727
101
Sautrey
G.
,
Zimmermann
L.
,
Deleu
M.
,
Delbar
A.
,
Souza Machado
L.
,
Jeannot
K.
et al
(
2014
)
New amphiphilic neamine derivatives active against resistant Pseudomonas aeruginosa and their interactions with lipopolysaccharides
.
Antimicrob. Agents Chemother.
58
,
4420
4430
102
Wu
G.-H.
and
Hsu
S.-H.
(
2016
)
Synthesis of water-based cationic polyurethane for antibacterial and gene delivery applications
.
Colloids Surf. B Biointerfaces
146
,
825
832
103
Choi
Y.H.
,
Liu
F.
,
Kim
J.-S.
,
Choi
Y.K.
,
Park
J.S.
and
Kim
S.W.
(
1998
)
Polyethylene glycol-grafted poly-l-lysine as polymeric gene carrier
.
J. Control. Release
54
,
39
48
104
Fajac
I.
,
Allo
J.C.
,
Souil
E.
,
Merten
M.
,
Pichon
C.
,
Figarella
C.
et al
(
2000
)
Histidylated polylysine as a synthetic vector for gene transfer into immortalized cystic fibrosis airway surface and airway gland serous cells
.
J. Gene Med.
2
,
368
378
105
Dubois
A.V.
,
Midoux
P.
,
Gras
D.
,
Si-Tahar
M.
,
Bréa
D.
,
Attucci
S.
et al
(
2013
)
Poly-L-Lysine compacts DNA, kills bacteria, and improves protease inhibition in cystic fibrosis sputum
.
Am. J. Respir. Crit. Care Med.
188
,
703
709
106
Shima
S.
,
Matsuoka
H.
,
Iwamoto
T.
and
Sakai
H.
(
1984
)
Antimicrobial action of epsilon-poly-L-lysine
.
J. Antibiot. (Tokyo)
37
,
1449
1455
107
Bertrand
E.
,
Gonçalves
C.
,
Billiet
L.
,
Gomez
J.P.
,
Pichon
C.
,
Cheradame
H.
et al
(
2011
)
Histidinylated linear PEI: a new efficient non-toxic polymer for gene transfer
.
Chem. Commun. Camb. Engl.
47
,
12547
12549
108
Shi
B.
,
Zheng
M.
,
Tao
W.
,
Chung
R.
,
Jin
D.
,
Ghaffari
D.
et al
(
2017
)
Challenges in DNA delivery and recent advances in multifunctional polymeric DNA delivery systems
.
Biomacromolecules
,
109
Davies
L.A.
,
McLachlan
G.
,
Sumner-Jones
S.G.
,
Ferguson
D.
,
Baker
A.
,
Tennant
P.
et al
(
2008
)
Enhanced lung gene expression after aerosol delivery of concentrated pDNA/PEI complexes
.
Mol. Ther.
16
,
1283
1290
110
Davies
L.A.
,
Hyde
S.C.
,
Nunez-Alonso
G.
,
Bazzani
R.P.
,
Harding-Smith
R.
,
Pringle
I.A.
et al
(
2012
)
The use of CpG-free plasmids to mediate persistent gene expression following repeated aerosol delivery of pDNA/PEI complexes
.
Biomaterials
33
,
5618
5627
111
Ma
Z.
and
Sun
W.
(
2014
)
The effect of aerosol polyethylenimine/interferon-γ plasmid complexes on expression of inflammatory cytokines in mouse lung
.
J. Aerosol. Med. Pulm. Drug Deliv.
27
,
117
124
112
Kolte
A.
,
Patil
S.
,
Lesimple
P.
,
Hanrahan
J.W.
and
Misra
A.
(
2017
)
PEGylated composite nanoparticles of PLGA and polyethylenimine for safe and efficient delivery of pDNA to lungs
.
Int. J. Pharm.
524
,
382
396
113
Azevedo
M.M.
,
Ramalho
P.
,
Silva
A.P.
,
Teixeira-Santos
R.
,
Pina-Vaz
C.
and
Rodrigues
A.G.
(
2014
)
Polyethyleneimine and polyethyleneimine-based nanoparticles: novel bacterial and yeast biofilm inhibitors
.
J. Med. Microbiol.
63
,
1167
1173
114
Barros
J.
,
Dias
A.
,
Rodrigues
M.A.
,
Pina-Vaz
C.
,
Lopes
M.A.
and
Pina-Vaz
I.
(
2015
)
Antibiofilm and antimicrobial activity of polyethylenimine: an interesting compound for endodontic treatment
.
J. Contemp. Dent. Pract.
16
,
427
432
115
Randazzo
R.A.S.
,
Bucki
R.
,
Janmey
P.A.
and
Diamond
S.L.
(
2009
)
A series of cationic sterol lipids with gene transfer and bactericidal activity
.
Bioorg. Med. Chem.
17
,
3257
3265
116
Myint
M.
,
Bucki
R.
,
Janmey
P.A.
and
Diamond
S.L.
(
2015
)
Synthesis and structure–activity relationships of novel cationic lipids with anti-inflammatory and antimicrobial activities
.
Bioorg. Med. Chem. Lett.
25
,
2837
2843
117
Hsu
W.-L.
,
Chen
H.-L.
,
Liou
W.
,
Lin
H.-K.
and
Liu
W.-L.
(
2005
)
Mesomorphic complexes of DNA with the mixtures of a cationic surfactant and a neutral lipid
.
Langmuir
21
,
9426
9431
118
Silva
J.P.N.
,
Oliveira
A.C.N.
,
Gomes
A.C.
and
Oliveira
M.E.C.D.R.
(
2012
)
Development of dioctadecyldimethylammonium bromide/monoolein liposomes for gene delivery
.
119
Ahlström
B.
,
Chelminska-Bertilsson
M.
,
Thompson
R.A.
and
Edebo
L.
(
1997
)
Submicellar complexes may initiate the fungicidal effects of cationic amphiphilic compounds on Candida albicans
.
Antimicrob. Agents Chemother.
41
,
544
550
120
Martins
L.M.S.
,
Mamizuka
E.M.
and
Carmona-Ribeiro
A.M.
(
1997
)
Cationic vesicles as bactericides
.
Langmuir
13
,
5583
5587
121
Campanhã
M.T.
,
Mamizuka
E.M.
and
Carmona-Ribeiro
A.M.
(
1999
)
Interactions between cationic liposomes and bacteria: the physical-chemistry of the bactericidal action
.
J. Lipid Res.
40
,
1495
1500
122
Kirby
A.J.
,
Camilleri
P.
,
Engberts
J.B.F.N.
,
Feiters
M.C.
,
Nolte
R.J.M.
,
Söderman
O.
et al
(
2003
)
Gemini surfactants: new synthetic vectors for gene transfection
.
Angew. Chem. Int. Ed. Engl.
42
,
1448
1457
123
Ahmed
T.
,
Kamel
A.O.
and
Wettig
S.D.
(
2016
)
Interactions between DNA and Gemini surfactant: impact on gene therapy: part I
.
Nanomedicine (London)
11
,
289
306
124
Obłąk
E.
,
Piecuch
A.
,
Guz-Regner
K.
and
Dworniczek
E.
(
2014
)
Antibacterial activity of gemini quaternary ammonium salts
.
FEMS Microbiol. Lett.
350
,
190
198
125
Berchel
M.
,
Gall
T.L.
,
Denis
C.
,
Hir
S.L.
,
Quentel
F.
,
Elléouet
C.
et al
(
2011
)
A silver-based metal–organic framework material as a “reservoir” of bactericidal metal ions
.
New J. Chem.
35
,
1000
1003
126
Peng
L.-H.
,
Huang
Y.-F.
,
Zhang
C.-Z.
,
Niu
J.
,
Chen
Y.
,
Chu
Y.
et al
(
2016
)
Integration of antimicrobial peptides with gold nanoparticles as unique non-viral vectors for gene delivery to mesenchymal stem cells with antibacterial activity
.
Biomaterials
103
,
137
149
127
Ghosh
P.
,
Han
G.
,
De
M.
,
Kim
C.K.
and
Rotello
V.M.
(
2008
)
Gold nanoparticles in delivery applications
.
Adv. Drug Deliv. Rev.
60
,
1307
1315
128
Lima
E.
,
Guerra
R.
,
Lara
V.
and
Guzmán
A.
(
2013
)
Gold nanoparticles as efficient antimicrobial agents for Escherichia coli and Salmonella typhi
.
Chem. Cent. J.
7
,
11
129
Shamaila
S.
,
Zafar
N.
,
Riaz
S.
,
Sharif
R.
,
Nazir
J.
and
Naseem
S.
(
2016
)
Gold nanoparticles: an efficient antimicrobial agent against enteric bacterial human pathogen
.
Nanomaterials
6
,
71
130
Li
X.
,
Obeidat
M.
,
Zhou
G.
,
Leung
J.M.
,
Tashkin
D.
,
Wise
R.
et al
(
2017
)
Responsiveness to ipratropium bromide in male and female patients with mild to moderate chronic obstructive pulmonary disease
.
EBioMedicine
19
,
139
145
131
Bjermer
L.
,
Gauvreau
G.M.
,
Postma
D.S.
,
O’Byrne
P.M.
,
van den Berge
M.
,
Boulet
L.-P.
et al
(
2017
)
Methacholine challenge tests to demonstrate therapeutic equivalence of terbutaline sulfate via different Turbuhaler(®) devices in patients with mild to moderate asthma: appraisal of a four-way crossover design
.
Pulm. Pharmacol. Ther.
44
,
1
6
132
Kerwin
E.M.
,
Ferro
T.J.
,
Ariely
R.
,
Irwin
D.E.
and
Parikh
R.
(
2017
)
Real-world health care utilization in asthma patients using albuterol sulfate inhalation aerosol (ProAir (®) HFA) with and without integrated dose counters
.
J. Asthma Allergy
10
,
171
179
133
Lewis
A.
,
Torvinen
S.
,
Dekhuijzen
P.N.R.
,
Chrystyn
H.
,
Melani
A.
,
Zöllner
Y.
et al
(
2017
)
Budesonide + formoterol delivered via Spiromax(®) for the management of asthma and COPD: The potential impact on unscheduled healthcare costs of improving inhalation technique compared with Turbuhaler(®)
.
Respir. Med.
129
,
179
188
134
Profita
M.
,
Riccobono
L.
,
Bonanno
A.
,
Chanez
P.
,
Gagliardo
R.
,
Montalbano
A.M.
et al
(
2013
)
Effect of nebulized beclomethasone on airway inflammation and clinical status of children with allergic asthma and rhinitis: a randomized, double-blind, placebo-controlled study
.
Int. Arch. Allergy Immunol.
161
,
53
64
135
Wang
X.
,
Koehne-Voss
S.
,
Anumolu
S.S.
and
Yu
J.
(
2017
)
Population pharmacokinetics of tobramycin inhalation solution in pediatric patients with cystic fibrosis
.
J. Pharm. Sci.
,
136
Greenwood
J.
,
Schwarz
C.
,
Sommerwerck
U.
,
Nash
E.F.
,
Tamm
M.
,
Cao
W.
et al
(
2017
)
Ease of use of tobramycin inhalation powder compared with nebulized tobramycin and colistimethate sodium: a crossover study in cystic fibrosis patients with pulmonary Pseudomonas aeruginosa infection
.
Ther. Adv. Respir. Dis.
11
,
249
260
137
Heirali
A.A.
,
Workentine
M.L.
,
Acosta
N.
,
Poonja
A.
,
Storey
D.G.
,
Somayaji
R.
et al
(
2017
)
The effects of inhaled aztreonam on the cystic fibrosis lung microbiome
.
Microbiome
5
,
51
138
Audag
N.
,
Liistro
G.
,
Van der Linden
D.
,
Smets
F.
,
Leal
T.
and
Reychler
G.
(
2017
)
In vitro and in vivo comparison of two nebulizers used for inhaled pentamidine delivery
.
Arch. Bronconeumol.
,
139
Tarrant
B.J.
,
Le Maitre
C.
,
Romero
L.
,
Steward
R.
,
Button
B.M.
,
Thompson
B.R.
et al
(
2017
)
Mucoactive agents for chronic, non-cystic fibrosis lung disease: a systematic review and meta-analysis
.
Respirol. Carlton. Vic.
22
,
1084
1092
140
Theodoraki
K.
,
Thanopoulos
A.
,
Rellia
P.
,
Leontiadis
E.
,
Zarkalis
D.
,
Perreas
K.
et al
(
2017
)
A retrospective comparison of inhaled milrinone and iloprost in post-bypass pulmonary hypertension
.
Heart Vessels
, DOI:
141
Netzer
N.C.
,
Küpper
T.
,
Voss
H.W.
and
Eliasson
A.H.
(
2012
)
The actual role of sodium cromoglycate in the treatment of asthma–a critical review
.
Sleep Breath.
16
,
1027
1032
142
Slaton
R.M.
,
Thomas
R.H.
and
Mbathi
J.W.
(
2013
)
Evidence for therapeutic uses of nebulized lidocaine in the treatment of intractable cough and asthma
.
Ann. Pharmacother.
47
,
578
585
143
Yin
H.
,
Kanasty
R.L.
,
Eltoukhy
A.A.
,
Vegas
A.J.
,
Dorkin
J.R.
and
Anderson
D.G.
(
2014
)
Non-viral vectors for gene-based therapy
.
Nat. Rev. Genet.
15
,
541
555
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