Inhaled lipid nanocarriers for pulmonary delivery of glucocorticoids: previous strategies, recent advances and key factors description

Trans-resveratrol-loaded nanostructured lipid carrier formulations for pulmonary drug delivery using medical nebulizers

Aerosolization is a non-invasive approach of delivering drugs for both localized and systemic effects, specifically pulmonary targeting. The aim of this study was to deliver trans-resveratrol (TR) as an anti-cancer drug entrapped in a new generation versatile carriers nanostructured lipid carrier (NLC) to protect degradation and improve bioavailability via medical nebulizers. Twelve TR-NLC (i.e., F1-F12) formulations were prepared using different combinations and ratios of formulation ingredients via hot high-pressure homogenization. Upon analysis, formulations F1 and F2 demonstrated a particle size of <185 nm, a polydispersity index (PDI) <0.25, Zeta potential values of ∼30 mV and an entrapment efficiency >94%. The aerosolization performance of the F1 and F2 formulations was performed via a next generation impactor (NGI), using medical nebulizers. The air jet nebulizer demonstrated lower drug deposition in the earlier stages (1-2) and significantly higher deposition in the latter stages 3-5 (for both formulations), targeting middle to lower lung deposition. Moreover, the air jet nebulizer exhibited significantly higher emitted dose (ED) (87.44 ± 3.36%), fine particle dose (FPD) (1652.52 ± 9.68 µg) fine particle fraction (FPF) (36.25 ± 4.26%), and respirable fraction (RF) (93.41 ± 4.03%) when the F1 formulation was used as compared to the F2 formulation. Thus, the TR-NLC F1 formulation and air jet nebulizer were identified as the best combination for the delivery and targeting peripheral lungs.

Effects of Surface Charge of Inhaled Liposomes on Drug Efficacy and Biocompatibility

Objectives: Liposomes are a promising drug carrier for inhaled delivery systems and their physical parameters could influence therapeutic efficacy significantly. This study was designed to answer the specific question of the proper surface charge of liposomes in pulmonary inhalation, as well as to study the synergistic anti-inflammation efficacy between drugs. Methods: In this work, a series of drug-loaded liposomes with different surface charges (from negative to positive) were prepared, and several in vitro and in vivo assays, including cytotoxicity, hemolysis assay, mucus penetration and lipopolysaccharide (LPS)-induced pneumonia model test, were adopted to evaluate the anti-inflammation efficacy and biocompatibility of the above liposomes. Results: Compared with cationic liposomes, anionic liposomes are capable of better mucus penetration and good biocompatibility (low cytotoxicity, better blood compatibility and mild tissue inflammation), but with poor cellular uptake by immune cells. In specific, even when the liposome surface charge was only +2.6 mV, its cytotoxicity and blood hemolysis reached around 20% and 15%, respectively. Furthermore, there was no significant difference in biocompatibility between anionic liposomes (-25.9 vs. -2.5 mV), but a slightly negative-charged liposome exhibited better cellular uptake. Conclusions: Thus, slightly negative-charged liposomes (-1~-3 mV) could be a well inhaled drug carrier considering both efficacy and biocompatibility. In an LPS-induced pneumonia mouse model, the drug-loaded liposomes achieved better anti-inflammatory efficacy compared with free drugs.

Nebulized Hybrid Nanoarchaeosomes: Anti-Inflammatory Activity, Anti-Microbial Activity and Cytotoxicity on A549 Cells

The properties of two hybrid nanoarchaeosomes (hybrid nanoARCs) made of archaeolipids extracted from the halophilic archaea Halorubrum tebenquichense and combining the properties of archaeolipid bilayers with metallic nanoparticles are explored here. BS-nanoARC, consisting of a nanoARC loaded with yerba mate (Ilex paraguariensis) extract (YME)-biogenic silver nanoparticles (BSs), and [BS + BS-nanoARC], consistent of a BS-nanoARC core covered by an outer shell of BSs, were structurally characterized and their therapeutic activities screened. By employing 109 ± 5 µg gallic acid equivalents (GAEs) and 73.4 µg chlorogenic acid/ YME mg as a silver reductive agent, spherical, heterogeneously sized (~80 nm diameter), -27 mV ζ potential, 90% Ag0 and λmax 420 nm BSs were obtained. We further prepared ~100-200 nm diameter, -57 mV ζ potential BS-nanoARC and ~300 nm diameter, -37 mV ζ potential [BS + BS-nanoARCs]. Freshly prepared and nebulized BS-nanoARCs reduced the release of TNF-α, IL-6 and IL-8 by LPS-irritated THP-1-macrophages and were highly anti-planktonic against S. aureus (MIC90: 13 ± 0.8 µg Ag/mL). While the nanoARCs and BS-nanoARCs were innocuous, freshly prepared [BS + BS-nanoARCs] magnified the cytotoxicity of BSs (IC50 12 µg Ag/mL vs. IC50 ~36 µg Ag/mL) on A549 cells. Such cytotoxicity remained after 30 days in the dark at 4 °C, while that of BSs was lost. Freshly prepared BSs also lost activity upon nebulization, whereas freshly prepared [BS + BS-nanoARCs] did not. However, the cytotoxicity of the [BS + BS-nanoARCs] was also lost when nebulized after 30 days of storage. Despite the harmful effects of storage and mechanical stress on the structure of the more active [BS + BS-nanoARCs], hybrid nanoARCs are promising examples of nanomedicines combining the properties of archaeolipids with antimicrobial silver nanoparticles and anti-inflammatory polyphenols that could complement oncologic therapies, reducing the usage of classical antitumoral agents, corticosteroids, and, importantly, of antibiotics, as well as their waste.

Investigating the effectiveness of liposome-bacteriophage nanocomplex in killing Staphylococcus aureus using epithelial cell coculture models

Host cell invasion with strong antibiotics evading is a major feature of respiratory Staphylococcus aureus infections with severe recurrence. Bacteriophage (phage) therapy and design of liposomal phage to target intracellular pathogens have been described recently. The practicality for pulmonary delivery of liposomal phage, and how formulation compositions affecting the aerosolization and intracellular bacterial killing remain unexplored. In the present study, three commonly used phospholipids (SPC, EPC, and HSPC) were selected to investigate their ability for phage K nebulization and intracellular therapy in the form of liposome-phage nanocomplexes. The three lipid nanocarriers showed protection on phage K upon mesh nebulization and the pulmonary deposition efficiency was influenced by the lipid used. Moreover, the intracellular bacterial killing was strongly depended on the lipid types, where EPC-phage exhibited the best killing performance with no relapsing. Phage K with the aid of EPC liposomes was also observed to manage the tissue infection in a 3D spheroid model more effectively than other groups. Altogether, this novel EPC liposome-phage nanocomplex can be a promising formulation approach that enables inhalable phage to manage respiratory infections caused by bacteria strongly associated with human epithelial cells.

Polyethylene Glycol-Modified Cationic Liposome as a Promising Nano Spray for Acute Pneumonia Treatment

Acute pneumonia (AP), triggered primarily by pathogens like bacteria and viruses, is a leading cause of human mortality. Ribavirin, a broad-spectrum antiviral agent, plays a pivotal role in the treatment of AP. However, its therapeutic use is hindered by the need for high dosages and the associated cardiac and hepatic toxicities. In this study, we synthesized polyethylene glycol-modified cationic liposomes to encapsulate ribavirin (RBV-PCL) and formulated it into a spray, aiming to enhance the effectiveness of RBV through respiratory administration. Lipopolysaccharide (LPS), a compound known to induce AP models in animals, was utilized in our research. Successfully, we established an acute pneumonia model in mice using aerosol inhalation. Through animal experiments, we investigated the therapeutic effects of RBV-PCL on mice with AP. In vivo studies revealed promising results. RBV-PCL effectively prolonged the survival of mice with AP, significantly reduced the levels of inflammatory markers such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), and inhibited the infiltration of neutrophils in the lungs and spleens of mice. These findings suggest that RBV-PCL can effectively suppress the inflammatory response in mice with AP, thus holding significant potential as a novel therapeutic approach for the treatment of acute pneumonia.

Aerosol inhalation of inflammatory cells-targeted dendrimer-dexamethasone conjugate for efficient allergic asthma therapy

Allergic asthma (AA) is a common breathing disorder clinically characterized by the high occurrence of acute and continuous inflammation. However, the current treatment options for AA are lacking in effectiveness and diversity. In this study, we determined that the cell membrane receptor of gamma-glutamyl transferase (GGT) was highly overexpressed on the inflammatory cells that infiltrate the pulmonary tissues in AA cases. Therefore, we developed a GGT-specific dendrimer-dexamethasone conjugate (GSHDDC) that could be administered via aerosol inhalation to treat AA in a rapid and sustained manner. The GSHDDC was fabricated by the covalent attachment of 6-hydroxyhexyl acrylate-modified dexamethasone to polyamidoamine dendrimers via a carbonic ester linkage and the amino Michael addition, followed by the surface modification of the dendrimers with the GGT substrate of glutathione. After aerosol inhalation by the AA mice, the small particle-sized GSHDDC could easily diffuse into pulmonary alveoli and touch with the inflammatory cells via the glutathione ligand/GGT receptor-mediated recognition. The overexpressed GGT on the surface of inflammatory cells then triggers the gamma-glutamyl transfer reactions of glutathione to generate positively charged primary amines, thereby inducing rapid cationization-mediated cellular endocytosis into the inflammatory cells. The dexamethasone was gradually released by the intracellular enzyme hydrolysis, enabling sustained anti-inflammatory effects (e.g., reducing eosinophil infiltration, decreasing the levels of inflammatory factors) in the ovalbumin-induced AA mice. This study demonstrates the effectiveness of an inhalational and active inflammatory cells-targeted dendrimer-dexamethasone conjugate for efficient AA therapy.

Natural Products-Based Inhaled Formulations for Treating Pulmonary Diseases

Given the unique physiological and pathological characteristics of the lung, the direct, inhalable route is more conducive to pulmonary drug delivery and disease control than traditional systemic drug delivery, significantly circumventing drug loss, off-target effects, systemic and organ toxicity, etc., and is widely regarded as the preferred regimen for pulmonary drug delivery. However, very few lung diseases are currently treated with the preferred inhaled formulations, such as asthma, chronic obstructive pulmonary disease and pulmonary hypertension. And there is a lack of appropriate inhaled formulations for other critical lung diseases, such as lung cancer and pulmonary fibrosis, due to the fact that the physicochemical properties of the drugs and their pharmacokinetic profiles do not match the physiology of the lung, and conventional inhalation devices are unable to deliver them to the specific parts of the lung. Phytochemicals of natural origin, due to their wide availability and clear safety profile, hold great promise for the preparation of inhalable formulations to improve the current dilemma in the treatment of lung diseases. In particular, the preparation of inhalable formulations based on nano- and microparticulate carriers for drug delivery to deep lung tissues, which overcome the shortcomings of conventional inhalation therapies while targeting the drug activity directly to a specific part of the lung, may be the best approach to change the current dilemma of lung disease treatment. In this review, we discuss recent advances in nano- and micron-carrier-based inhalation formulations for the delivery of natural products for the treatment of pulmonary diseases, which may represent an opportunity for practical clinical translation of natural products.