Challenges and strategies in drug delivery systems for treatment of pulmonary infections

On the potential of the WSi12 superatom as a drug carrier: a DFT study

The adsorption behaviors of 5-fluorouracil (5-Fu), 5-aminosalicylic acid (5-ASA), isoniazid (INH), 6-thioguanine (6-TG), and temozolomide (TMZ) onto the WSi12 superatom have been studied using density functional theory calculations to explore its potential application in drug delivery. Our results demonstrate that 5-Fu is bound to WSi12via very weak interaction with a small Ead value of -11.62 kcal mol-1, while the tight adsorption of TMZ greatly deforms this superatom and results in a high Edef value of 86.92 kcal mol-1, suggesting that WSi12 is not suitable to serve as a carrier for these two drugs. Fortunately, 5-ASA, INH, and 6-TG can be effectively bound to WSi12via forming polar covalent bonds in the resulting 5-ASA@WSi12, INH@WSi12, and 6-TG@WSi12 with the Ead values of -25.71 kcal mol-1, -19.65 kcal mol-1, and -24.24 kcal mol-1, respectively. As a result, the recovery time for the release of these drugs is moderate, indicating that this superatom can be regarded as a potential carrier for 5-ASA, INH, and 6-TG. Moreover, it is found that the Ead value of 6-TG@WSi12 is reduced from -24.24 to -15.29 kcal mol-1 under weakly acidic conditions, and the drug delivery performances of WSi12-extended WnSi6(n+1) (n = 2, 4, and 6) nanostructures are better than that of a single WSi12 superatom. We hope that this study could provide a valuable reference for further experiments on using such WSin clusters as novel drug delivery carriers.

Inhalable spray-dried porous microparticles containing dehydroandrographolide succinate phospholipid complex capable of improving and prolonging pulmonary anti-inflammatory efficacy in mice

Due to the unique physiological barriers within the lungs, there are considerable challenges in developing drug delivery systems enabling prolonged drug exposure to respiratory epithelial cells. Here, we report a PulmoSphere-based dry powder technology that incorporates a drug-phospholipid complex to promote intracellular retention of dehydroandrographolide succinate (DAS) in respiratory epithelial cells following pulmonary delivery. The DAS-phospholipid complex has the ability to self-assemble into nanoparticles. After spray-drying to produce PulmoSphere microparticles loaded with the drug-phospholipid complex, the rehydrated microparticles discharge the phospholipid complex without altering its physicochemical properties. The microparticles containing the DAS-phospholipid complex exhibit remarkable aerodynamic properties with a fine particle fraction of ∼ 60% and a mass median aerodynamic diameter of ∼ 2.3 μm. These properties facilitate deposition in the alveolar region. In vitro cell culture and lung tissue explants experiments reveal that the drug-phospholipid complex prolongs intracellular residence time and lung tissue retention due to the slow intracellular disassociation of drug from the complex. Once deposited in the lungs, the DAS-phospholipid complex loaded microparticles increase and extend drug exposure to the lung tissues and the immune cells compared to the free DAS counterpart. The improved drug exposure to airway epithelial cells, but not immune cells, is related to a prolonged duration of pulmonary anti-inflammation at decreased doses in a mouse model of acute lung injury induced by lipopolysaccharide. Overall, the phospholipid complex loaded microparticles present a promising approach for improved treatment of respiratory diseases, e.g. pneumonia and acute respiratory distress syndrome.

Nebulized inhalation drug delivery: clinical applications and advancements in research

Nebulized inhalation administration refers to the dispersion of drugs into small droplets suspended in the gas through a nebulized device, which are deposited in the respiratory tract by inhalation, to achieve the local therapeutic effect of the respiratory tract. Compared with other drug delivery methods, nebulized inhalation has the advantages of fast effect, high local drug concentration, less dosage, convenient application and less systemic adverse reactions, and has become one of the main drug delivery methods for the treatment of respiratory diseases. In this review, we first discuss the characteristics of nebulized inhalation, including its principles and influencing factors. Next, we compare the advantages and disadvantages of different types of nebulizers. Finally, we explore the clinical applications and recent research developments of nebulized inhalation therapy. By delving into these aspects, we aim to gain a deeper understanding of its pivotal role in contemporary medical treatment.

Innovative Microencapsulation of Polymyxin B for Enhanced Antimicrobial Efficacy via Coated Spray Drying

This study aims to develop an innovative microencapsulation method for coated Polymyxin B, utilizing various polysaccharides such as hydroxypropyl β-cyclodextrin, alginate, and chitosan, implemented through a three-fluid nozzle (3FN) spray drying process. High-performance liquid chromatography (HPLC) analysis revealed that formulations with a high ratio of sugar cage, hydroxypropyl β-cyclodextrin (HPβCD), and sodium alginate (coded as ALGHCDHPLPM) resulted in a notable 16-fold increase in Polymyxin B recovery compared to chitosan microparticles. Morphological assessments using fluorescence labeling confirmed successful microparticle formation with core/shell structures. Alginate-based formulations exhibited distinct layers, while chitosan formulations showed uniform fluorescence throughout the microparticles. Focused beam reflectance and histograms from fluorescence microscopic measurements provided insights into physical size analysis, indicating consistent sizes of 6.8 ± 1.2 μm. Fourier-transform infrared (FTIR) spectra unveiled hydrogen bonding between Polymyxin B and other components within the microparticle structures. The drug release study showed sodium alginate's sustained release capability, reaching 26 ± 3% compared to 94 ± 3% from the free solution at the 24 h time point. Furthermore, the antimicrobial properties of the prepared microparticles against two Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, were investigated. The influence of various key excipients on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values was evaluated. Results demonstrated effective bactericidal effects of ALGHCDHPLPM against both E. coli and P. aeruginosa. Additionally, the antibiofilm assay highlighted the potential efficacy of ALGHCDHPLPM against the biofilm viability of E. coli and P. aeruginosa, with concentrations ranging from 3.9 to 500 μg/m. This signifies a significant advancement in antimicrobial drug delivery systems, promising improved precision and efficacy in combating bacterial infections.

Development and Characterization of Spray-Dried Combined Levofloxacin-Ambroxol Dry Powder Inhaler Formulation

Background: This study explores the development and characterization of spray-dried composite microparticles consisting of levofloxacin (LVX, a broad-spectrum antibiotic), and ambroxol (AMB, a mucolytic agent that has antibacterial and antibiofilm properties), for the intended application of the drug against lower respiratory tract infections (LRTIs). Methods: A range of LVX to AMB mass ratios (1:1, 1:0.5, and 1:0.25) were prepared, with and without the use of the dispersibility enhancer leucine (LEU), and spray-dried following pre-optimized parameters to achieve the required particle size (1-5 µm) and flow properties. The formulations were characterized by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and a thermogravimetric analysis (TGA). The in vitro aerosolization performance of the new formulation was evaluated with a twin-stage impinger (TSI) at a flow rate of 60 ± 5 L/min. Using a validated RP-HPLC method, LVX and AMB were quantitatively determined. Results: The combined spray-dried LVX, AMB, and LEU particles were spherically shaped with sizes ranging from 1.9 to 2.9 µm, thus complying with the size requirements for effective deep lung deposition. The dispersibility enhancer leucine produced a high yield and enhanced the flow properties and aerosolization characteristics of the spray-dried formulations. The LVX to AMB mass ratios showed a remarkable impact on the aerosolization properties, with the LVX to AMB 1:1 mass ratio demonstrating the best flow and FPFs for both drugs. There must be a balanced ratio of these components for spray drying the composite particles to obtain composite particles of the required size and with the appropriate flow property. The addition of 5% of LEU significantly (p < 0.005) improved the FPF of all the formulations, probably by enhancing the surface hydrophobicity of the composite particles. Conclusions: The spray-dried combined antibiotics formulation has a strong potential for efficient lung delivery intended for the management of LRTIs.

Mesenchymal stem cell application in pulmonary disease treatment with emphasis on their interaction with lung-resident immune cells

Due to the vital importance of the lungs, lung-related diseases and their control are very important. Severe inflammatory responses mediated by immune cells were among the leading causes of lung tissue pathology and damage during the COVID-19 pandemic. In addition, uncontrolled immune cell responses can lead to lung tissue damage in other infectious and non-infectious diseases. It is essential to control immune responses in a way that leads to homeostasis. Immunosuppressive drugs only suppress inflammatory responses and do not affect the homeostasis of reactions. The therapeutic application of mesenchymal stem cells (MSCs), in addition to restoring immune homeostasis, can promote the regeneration of lung tissue through the production of growth factors and differentiation into lung-related cells. However, the communication between MSCs and immune cells after treatment of pulmonary diseases is essential, and investigating this can help develop a clinical perspective. Different studies in the clinical phase showed that MSCs can reverse fibrosis, increase regeneration, promote airway remodeling, and reduce damage to lung tissue. The proliferation and differentiation potential of MSCs is one of the mechanisms of their therapeutic effects. Furthermore, they can secrete exosomes that affect the function of lung cells and immune cells and change their function. Another important mechanism is that MSCs reduce harmful inflammatory responses through communication with innate and adaptive immune cells, which leads to a shift of the immune system toward regulatory and hemostatic responses.

The Role of Pulmonary Drug Delivery in Modern Therapeutics: An Overview

The pulmonary drug delivery system is a promising and evolving technology in which the prescribed medicine is breathed through the lungs, and subsequently, it enters the circulation via the alveolar epithelium. This category of pulmonary drug delivery system is an appealing and non-invasive administration method. Pulmonary drug delivery is most commonly utilized to treat airway problems by providing locally active medicines directly to their site of action. The dose required to have a pharmacological effect is reduced when medicines are delivered directly to their site of action. In addition to locally acting medications, the pulmonary route can be utilized to deliver compounds with systemic effects, such as in the case of insulin inhalation therapy for systemic absorption. Particle size, bioavailability, device compatibility, and other aspects must be addressed, including the formulation of drugs into an acceptable dosage for inhalation with sufficient stability. This formulation must also be used in conjunction with a suitable inhaler device that produces an aerosol with a particle or droplet size that assures deposition in the required targeted area of the pulmonary system. Recent advancements in pulmonary drug delivery include the development of targeted nanoparticles and inhalable biologics, which enhance drug absorption and efficacy while minimizing systemic side effects. Future directions focus on personalized medicine approaches and advanced inhalation technologies, although limitations such as variable patient adherence and the need for precise dosing continue to pose challenges.

Beyond antibiotics: Emerging antivirulence strategies to combat Pseudomonas aeruginosa in cystic fibrosis

Pseudomonas aeruginosa is an opportunistic pathogen that poses a significant threat to individuals suffering from cystic fibrosis (CF). The pathogen is highly prevalent in CF individuals and is responsible for chronic infection, resulting in severe tissue damage and poor patient outcome. Prolonged antibiotic administration has led to the emergence of multidrug resistance in P. aeruginosa. In this direction, antivirulence strategies achieving targeted inhibition of bacterial virulence pathways, including quorum sensing, efflux pumps, lectins, and iron chelators, have been explored against CF isolates of P. aeruginosa. Hence, this review article presents a bird's eye view on the pulmonary infections involving P. aeruginosa in CF patients by laying emphasis on factors contributing to bacterial colonization, persistence, and disease progression along with the current line of therapeutics against P. aeruginosa in CF. We further collate scientific literature and discusses various antivirulence strategies that have been tested against P. aeruginosa isolates from CF patients.

Investigation of Factors Influencing the Effectiveness of Deformable Nanovesicles for Insulin Nebulization Inhalation

Nebulized inhalation offers a noninvasive method for delivering drugs to treat both local respiratory and systemic diseases. In this study, insulin was used as a model drug to design a series of deformable nanovesicles (DNVs) with key quality attributes, including particle size, deformability, and drug load capacity. We investigated the effects of these properties on aerosol generation, macrophage phagocytosis, and bloodstream penetration. The results showed that deformability improved nebulization performance and reduced macrophage phagocytosis, benefiting local and systemic delivery. However, the advantage of DNVs for transmembrane penetration was not evident in the alveolar epithelium. Within the size range of 80-490 nm, the smaller the particle size of IPC-DNVs, the easier it is to evade clearance by macrophages and the more effective the in vivo hypoglycemic efficacy will be. In the drug load range of 3-5 mg/mL, a lower drug load resulted in better hypoglycemic efficacy. The area above the blood glucose decline curve with time (AAC) of nebulized DNVs was 2.32 times higher than that of the insulin solution, demonstrating the feasibility and advantages of DNVs in the pulmonary delivery of biomacromolecule drugs. This study provides insights into the construction and formulation optimization of pulmonary delivery carriers.

Ciprofloxacin-Loaded Inhalable Formulations against Lower Respiratory Tract Infections: Challenges, Recent Advances, and Future Perspectives

Inhaled ciprofloxacin (CFX) has been investigated as a treatment for lower respiratory tract infections (LRTIs) associated with cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and bronchiectasis. The challenges in CFX effectiveness for LRTI treatment include poor aqueous solubility and therapy resistance. CFX dry powder for inhalation (DPI) formulations were well-tolerated, showing a remarkable decline in overall bacterial burden compared to a placebo in bronchiectasis patients. Recent research using an inhalable powder combining Pseudomonas phage PEV20 with CFX exhibited a substantial reduction in bacterial density in mouse lungs infected with clinical P. aeruginosa strains and reduced inflammation. Currently, studies suggest that elevated biosynthesis of fatty acids could serve as a potential biomarker for detecting CFX resistance in LRTIs. Furthermore, inhaled CFX has successfully addressed various challenges associated with traditional CFX, including the incapacity to eliminate the pathogen, the recurrence of colonization, and the development of resistance. However, further exploration is needed to address three key unresolved issues: identifying the right patient group, determining the optimal treatment duration, and accurately assessing the risk of antibiotic resistance, with additional multicenter randomized controlled trials suggested to tackle these challenges. Importantly, future investigations will focus on the effectiveness of CFX DPI in bronchiectasis and COPD, aiming to differentiate prognoses between these two conditions. This review underscores the importance of CFX inhalable formulations against LRTIs in preclinical and clinical sectors, their challenges, recent advancements, and future perspectives.

Pulmonary inhalation for disease treatment: Basic research and clinical translations

Pulmonary drug delivery has the advantages of being rapid, efficient, and well-targeted, with few systemic side effects. In addition, it is non-invasive and has good patient compliance, making it a highly promising drug delivery mode. However, there have been limited studies on drug delivery via pulmonary inhalation compared with oral and intravenous modes. This paper summarizes the basic research and clinical translation of pulmonary inhalation drug delivery for the treatment of diseases and provides insights into the latest advances in pulmonary drug delivery. The paper discusses the processing methods for pulmonary drug delivery, drug carriers (with a focus on various types of nanoparticles), delivery devices, and applications in pulmonary diseases and treatment of systemic diseases (e.g., COVID-19, inhaled vaccines, diagnosis of the diseases, and diabetes mellitus) with an updated summary of recent research advances. Furthermore, this paper describes the applications and recent progress in pulmonary drug delivery for lung diseases and expands the use of pulmonary drugs for other systemic diseases.

Nanomedicine against biofilm infections: A roadmap of challenges and limitations

Microbial biofilms are complex three-dimensional structures where sessile microbes are embedded in a polymeric extracellular matrix. Their resistance toward the host immune system as well as to a diverse range of antimicrobial treatments poses a serious health and development threat, being in the top 10 global public health threats declared by the World Health Organization. In an effort to combat biofilm-related microbial infections, several strategies have been developed to independently eliminate biofilms or to complement conventional antibiotic therapies. However, their limitations leave room for other treatment alternatives, where the application of nanotechnology to biofilm eradication has gained significant relevance in recent years. Their small size, penetration efficiency, and the design flexibility that they present makes them a promising alternative for biofilm infection treatment, although they also present set-backs. This review aims to describe the main possibilities and limitations of nanomedicine against biofilms, while covering the main aspects of biofilm formation and study, and the current therapies for biofilm treatment. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Drug repurposing for the treatment of COVID-19: Targeting nafamostat to the lungs by a liposomal delivery system

Despite tremendous global efforts since the beginning of the COVID-19 pandemic, still only a limited number of prophylactic and therapeutic options are available. Although vaccination is the most effective measure in preventing morbidity and mortality, there is a need for safe and effective post-infection treatment medication. In this study, we explored a pipeline of 21 potential candidates, examined in the Calu-3 cell line for their antiviral efficacy, for drug repurposing. Ralimetinib and nafamostat, clinically used drugs, have emerged as attractive candidates. Due to the inherent limitations of the selected drugs, we formulated targeted liposomes suitable for both systemic and intranasal administration. Non-targeted and targeted nafamostat liposomes (LipNaf) decorated with an Apolipoprotein B peptide (ApoB-P) as a specific lung-targeting ligand were successfully developed. The developed liposomal formulations of nafamostat were found to possess favorable physicochemical properties including nano size (119-147 nm), long-term stability of the normally rapidly degrading compound in aqueous solution, negligible leakage from the liposomes upon storage, and a neutral surface charge with low polydispersity index (PDI). Both nafamostat and ralimetinib liposomes showed good cellular uptake and lack of cytotoxicity, and non-targeted LipNaf demonstrated enhanced accumulation in the lungs following intranasal (IN) administration in non-infected mice. LipNaf retained its anti-SARS-CoV 2 activity in Calu 3 cells with only a modest decrease, exhibiting complete inhibition at concentrations >100 nM. IN, but not intraperitoneal (IP) treatment with targeted LipNaf resulted in a trend to reduced viral load in the lungs of K18-hACE2 mice compared to targeted empty Lip. Nevertheless, upon removal of outlier data, a statistically significant 1.9-fold reduction in viral load was achieved. This observation further highlights the importance of a targeted delivery into the respiratory tract. In summary, we were able to demonstrate a proof-of-concept of drug repurposing by liposomal formulations with anti-SARS-CoV-2 activity. The biodistribution and bioactivity studies with LipNaf suggest an IN or inhalation route of administration for optimal therapeutic efficacy.

Review of inhalable nanoparticles for the pulmonary delivery of anti-tuberculosis drugs

Tuberculosis is an airborne disease caused by the pathogen, Mycobacterium tuberculosis, which predominantly affects the lungs. World Health Organization (WHO) has reported that about 85% of TB patients are cured with the existing 6-month antibiotic regimen. However, the lengthy oral administration of high-dose anti-TB drugs is associated with significant side effects and leads to drug resistance cases. Alternatively, reformulating existing anti-tubercular drugs into inhalable nanoparticulate systems is a promising strategy to overcome the challenges associated with oral treatment as they could enhance drug retention in the pulmonary region to achieve an optimal drug concentration in the infected lungs. Hence, this review provides an overview of the literature on inhalable nano-formulations for the delivery of anti-TB drugs, including their formulation techniques and preclinical evaluations between the years 2000 and 2020, gathered from electronic journals via online search engines such as Google Scholar and PubMed. Previous in vitro and in vivo studies highlighted that the nano-size, low toxicity, and high efficacy were among the factors influencing the fate of nanoparticulate system upon deposition in the lungs. Although many preclinical studies have shown that inhalable nanoparticles increased therapeutic efficacy and minimised adverse drug reactions when delivered through the pulmonary route, none of them has progressed into clinical trials to date. This could be attributed to the high cost of inhaled regimes due to the expensive production and characterisation of the nanoparticles as well as the need for an inhalation device as compared to the oral treatment. Another barrier could be the lack of medical acceptance due to insufficient number of trained staff to educate the patients on the correct usage of the inhalation device. Hence, these barriers should be addressed satisfactorily to make the inhaled nanoparticles regimen a reality for the treatment of TB.

Liposomal drug delivery to the lungs: a post covid-19 scenario

High local delivery of anti-infectives to the lungs is required for activity against infections of the lungs. The present pandemic has highlighted the potential of pulmonary delivery of anti-infective agents as a viable option for infections like Covid-19, which specifically causes lung infections and mortality. To prevent infections of such type and scale in the future, target-specific delivery of drugs to the pulmonary region is a high-priority area in the field of drug delivery. The suboptimal effect of oral delivery of anti-infective drugs to the lungs due to the poor biopharmaceutical property of the drugs makes this delivery route very promising for respiratory infections. Liposomes have been used as an effective delivery system for drugs due to their biocompatible and biodegradable nature, which can be used effectively for target-specific drug delivery to the lungs. In the present review, we focus on the use of liposomal drug delivery of anti-infectives for the acute management of respiratory infections in the wake of Covid-19 infection.

Harnessing three-dimensional (3D) cell culture models for pulmonary infections: State of the art and future directions

Pulmonary infections have been a leading etiology of morbidity and mortality worldwide. Upper and lower respiratory tract infections have multifactorial causes, which include bacterial, viral, and rarely, fungal infections. Moreover, the recent emergence of SARS-CoV-2 has created havoc and imposes a huge healthcare burden. Drug and vaccine development against these pulmonary pathogens like respiratory syncytial virus, SARS-CoV-2, Mycobacteria, etc., requires a systematic set of tools for research and investigation. Currently, in vitro 2D cell culture models are widely used to emulate the in vivo physiologic environment. Although this approach holds a reasonable promise over pre-clinical animal models, it lacks the much-needed correlation to the in vivo tissue architecture, cellular organization, cell-to-cell interactions, downstream processes, and the biomechanical milieu. In view of these inadequacies, 3D cell culture models have recently acquired interest. Mammalian embryonic and induced pluripotent stem cells may display their remarkable self-organizing abilities in 3D culture, and the resulting organoids replicate important structural and functional characteristics of organs such the kidney, lung, gut, brain, and retina. 3D models range from scaffold-free systems to scaffold-based and hybrid models as well. Upsurge in organs-on-chip models for pulmonary conditions has anticipated encouraging results. Complexity and dexterity of developing 3D culture models and the lack of standardized working procedures are a few of the setbacks, which are expected to be overcome in the coming times. Herein, we have elaborated the significance and types of 3D cell culture models for scrutinizing pulmonary infections, along with the in vitro techniques, their applications, and additional systems under investigation.

Poly(sebacic acid) microparticles loaded with azithromycin as potential pulmonary drug delivery system: Physicochemical properties, antibacterial behavior, and cytocompatibility studies

Recurrent bacterial infections are a common cause of death for patients with cystic fibrosis and chronic obstructive pulmonary disease. Herein, we present the development of the degradable poly(sebacic acid) (PSA) microparticles loaded with different concentrations of azithromycin (AZ) as a potential powder formulation to deliver AZ locally to the lungs. We characterized microparticle size, morphology, zeta potential, encapsulation efficiency, interaction PSA with AZ and degradation profile in phosphate buffered saline (PBS). The antibacterial properties were evaluated using the Kirby-Bauer method against Staphylococcus aureus. Potential cytotoxicity was evaluated in BEAS-2B and A549 lung epithelial cells by the resazurin reduction assay and live/dead staining. The results show that microparticles are spherical and their size, being in the range of 1-5 μm, should be optimal for pulmonary delivery. The AZ encapsulation efficiency is nearly 100 % for all types of microparticles. The microparticles degradation rate is relatively fast - after 24 h their mass decreased by around 50 %. The antibacterial test showed that released AZ was able to successfully inhibit bacteria growth. The cytotoxicity test showed that the safe concentration of both unloaded and AZ-loaded microparticles was equal to 50 μg/ml. Thus, appropriate physicochemical properties, controlled degradation and drug release, cytocompatibility, and antibacterial behavior showed that our microparticles may be promising for the local treatment of lung infections.

Advancements in Chitosan-Based Nanoparticles for Pulmonary Drug Delivery

The evolution of respiratory diseases represents a considerable public health challenge, as they are among the leading causes of death worldwide. In this sense, in addition to the high prevalence of diseases such as asthma, chronic obstructive pulmonary disease, pneumonia, cystic fibrosis, and lung cancer, emerging respiratory diseases, particularly those caused by members of the coronavirus family, have contributed to a significant number of deaths on a global scale over the last two decades. Therefore, several studies have been conducted to optimize the efficacy of treatments against these diseases, focusing on pulmonary drug delivery using nanomedicine. Thus, the development of nanocarriers has emerged as a promising alternative to overcome the limitations of conventional therapy, by increasing drug bioavailability at the target site and reducing unwanted side effects. In this context, nanoparticles composed of chitosan (CS) show advantages over other nanocarriers because chitosan possesses intrinsic biological properties, such as anti-inflammatory, antimicrobial, and mucoadhesive capacity. Moreover, CS nanoparticles have the potential to enhance drug stability, prolong the duration of action, improve drug targeting, control drug release, optimize dissolution of poorly soluble drugs, and increase cell membrane permeability of hydrophobic drugs. These properties could optimize the performance of the drug after its pulmonary administration. Therefore, this review aims to discuss the potential of chitosan nanoparticles for pulmonary drug delivery, highlighting how their biological properties can improve the treatment of pulmonary diseases, including their synergistic action with the encapsulated drug.

In Vitro and In Vivo Evaluation of Inhalable Ciprofloxacin Sustained Release Formulations

Respiratory antibiotics delivery has been appreciated for its high local concentration at the infection sites. Certain formulation strategies are required to improve pulmonary drug exposure and to achieve effective antimicrobial activity, especially for highly permeable antibiotics. This study aimed to investigate lung exposure to various inhalable ciprofloxacin (CIP) formulations with different drug release rates in a rat model. Four formulations were prepared, i.e., CIP-loaded PLGA micro-particles (CHPM), CIP microcrystalline dry powder (CMDP), CIP nanocrystalline dry powder (CNDP), and CIP spray-dried powder (CHDP), which served as a reference. The physicochemical properties, drug dissolution rate, and aerosolization performance of these powders were characterized in vitro. Pharmacokinetic profiles were evaluated in rats. All formulations were suitable for inhalation (mass median aerodynamic diameter < 5 µm). CIP in CHPM and CHDP was amorphous, whereas the drug in CMDP and CNDP remained predominantly crystalline. CHDP exhibited the fastest drug release rate, while CMDP and CNDP exhibited much slower drug release. In addition, CMDP and CNDP exhibited significantly higher in vivo lung exposure to CIP compared with CHDP and CHPM. This study suggests that lung exposure to inhaled drugs with high permeability is governed by drug release rate, implying that lung exposure of inhaled antibiotics could be improved by a sustained-release formulation strategy.

Review on PLGA Polymer Based Nanoparticles with Antimicrobial Properties and Their Application in Various Medical Conditions or Infections

The rise in the resistance to antibiotics is due to their inappropriate use and the use of a broad spectrum of antibiotics. This has also contributed to the development of multidrug-resistant microorganisms, and due to the unavailability of suitable new drugs for treatments, it is difficult to control. Hence, there is a need for the development of new novel, target-specific antimicrobials. Nanotechnology, involving the synthesis of nanoparticles, may be one of the best options, as it can be manipulated by using physicochemical properties to develop intelligent NPs with desired properties. NPs, because of their unique properties, can deliver drugs to specific targets and release them in a sustained fashion. The chance of developing resistance is very low. Polymeric nanoparticles are solid colloids synthesized using either natural or synthetic polymers. These polymers are used as carriers of drugs to deliver them to the targets. NPs, synthesized using poly-lactic acid (PLA) or the copolymer of lactic and glycolic acid (PLGA), are used in the delivery of controlled drug release, as they are biodegradable, biocompatible and have been approved by the USFDA. In this article, we will be reviewing the synthesis of PLGA-based nanoparticles encapsulated or loaded with antibiotics, natural products, or metal ions and their antibacterial potential in various medical applications.

Drug combinations for inhalation: Current products and future development addressing disease control and patient compliance

Pulmonary delivery is an alternative route of administration with numerous advantages over conventional routes of administration. It provides low enzymatic exposure, fewer systemic side effects, no first-pass metabolism, and concentrated drug amounts at the site of the disease, making it an ideal route for the treatment of pulmonary diseases. Owing to the thin alveolar-capillary barrier, and large surface area that facilitates rapid absorption to the bloodstream in the lung, systemic delivery can be achieved as well. Administration of multiple drugs at one time became urgent to control chronic pulmonary diseases such as asthma and COPD, thus, development of drug combinations was proposed. Administration of medications with variable dosages from different inhalers leads to overburdening the patient and may cause low therapeutic intervention. Therefore, products that contain combined drugs to be delivered via a single inhaler have been developed to improve patient compliance, reduce different dose regimens, achieve higher disease control, and boost therapeutic effectiveness in some cases. This comprehensive review aimed to highlight the growth of drug combinations by inhalation over time, obstacles and challenges, and the possible progress to broaden the current options or to cover new indications in the future. Moreover, various pharmaceutical technologies in terms of formulation and device in correlation with inhaled combinations were discussed in this review. Hence, inhaled combination therapy is driven by the need to maintain and improve the quality of life for patients with chronic respiratory diseases; promoting drug combinations by inhalation to a higher level is a necessity.

Systemic Protein Delivery via Inhalable Liposomes: Formulation and Pharmacokinetics

The enormous and thin alveolar epithelium is an attractive site for systemic protein delivery. Considering the excellent biocompatibility of phospholipids with endogenous pulmonary surfactant, we engineered dimyristoylphosphatidylcholine (DMPC)-based liposomes for pulmonary administration, using Cy5.5-labeled bovine serum albumin (BSA-Cy5.5) as a model protein payload. The level of cholesterol (Chol) and surface modification with PEG in inhalable liposomes were optimized iteratively based on the encapsulation efficiency, the release kinetics in the simulated lung fluid, and the uptake in murine RAW 264.7 macrophages. The plasma pharmacokinetics of BSA-Cy5.5-encapsulated liposomes with the composition of DMPC/Chol/PEG at 85:10:5 (molar ratio) was studied in mice following intratracheal aerosolization, in comparison with that of free BSA-Cy5.5 solution. The biodisposition of BSA-Cy5.5 was continuously monitored using whole-body near-infrared (NIR) fluorescence imaging for 10 days. We found that the systemic bioavailability of BSA-Cy5.5 from inhaled liposomes was 22%, which was notably higher than that of inhaled free BSA-Cy5.5. The mean residence time of BSA-Cy5.5 was markedly prolonged in mice administered intratracheally with liposomal BSA-Cy5.5, which is in agreement with the NIR imaging results. Our work demonstrates the great promise of inhalable DMPC-based liposomes to achieve non-invasive systemic protein delivery.

The pulmonary biopharmaceutics and anti-inflammatory effects after intratracheal and intravenous administration of Re-Du-Ning injection

BACKGROUND

Re-Du-Ning injection (RDN) is a renowned heat-clearing traditional Chinese medicine for the treatment of respiratory diseases owing to its anti-inflammatory effects. However, very little is known about the pulmonary distribution and lung exposure-efficacy relationships. This study aimed to investigate the pulmonary distribution and biopharmaceutics concerning lung penetrability and affinity and the local anti-inflammatory effects after intravenous and pulmonary administration of RDN.

METHODS

Two iridoids and seven phenolic acid components were selected as the chemical markers in RDN. The in vitro pulmonary distribution and biopharmaceutics were conducted by evaluating the binding and disassociation kinetics of chemical markers in lung tissue explants whereas the in vivo evaluation was performed by determining the time-dependent concentrations of chemical markers in plasma, lung epithelial lining fluid (ELF), lung tissues and immune cells in the ELF after intratracheal and intravenous administrations of RDN. The inhibitory effects on tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production were used to evaluate the anti-inflammatory effect of RDN on lung tissues in vitro and on mice with LPS-induced lung inflammation.

RESULTS

The chemical markers of RDN exhibited excellent lung penetrability but poor lung affinity in vitro and in vivo. After intravenous administration, the chemical markers appeared to rapidly penetrate through the lung tissue to reach the ELF, leading to markedly higher drug exposure to ELF and immune cells in the ELF than to lung tissues. Compared to intravenous injection, the intratracheal instillation of RDN increased drug exposure to lung tissue and immune cells in the ELF by up to > 80-fold, leading to improved anti-inflammatory potency and prolonged duration of action.

CONCLUSION

The drug exposure to immune cells in the ELF was correlated with the lung-targeted anti-inflammatory effects of RDN and pulmonary delivery has the potential to replace intravenous injection of RDN for the treatment of respiratory diseases.

Microfluidics assembly of inhalable liposomal ciprofloxacin characterised by an innovative in vitro pulmonary model

Respiratory tract infections (RTIs) are reported to be the leading cause of death worldwide. Delivery of liposomal antibiotic nano-systems via the inhalation route has drawn significant interest in RTIs treatment as it can directly target the site of infection and reduces the risk of systemic exposure and side effects. Moreover, this formulation system can improve pharmacokinetics and biodistribution and enhance the activity against intracellular pathogens. Microfluidics is an innovative manufacturing technology that can produce nanomedicines in a homogenous and scalable way. The objective of this study was to evaluate the antibiofilm efficacy of two liposomal ciprofloxacin formulations with different vesicle sizes manufactured by using a 3D-printed microfluidic chip. Each formulation was characterised in terms of size, polydispersity index, charge and encapsulation. Moreover, the aerosolisation characteristics of the liposomal formulations were investigated and compared with free ciprofloxacin solution using laser diffraction and cascade impaction methods. The in vitro drug release was tested using the dialysis bag method. Furthermore, the drug transport and drug release studies were conducted using the alveolar epithelial H441 cell line integrated next-generation impactor in vitro model. Finally, the biofilm eradication efficacy was evaluated using a dual-chamber microfluidic in vitro model. Results showed that both liposomal-loaded ciprofloxacin formulations and free ciprofloxacin solution had comparable aerosolisation characteristics and biofilm-killing efficacy. The liposomal ciprofloxacin formulation of smaller vesicle size showed significantly slower drug release in the dialysis bag technique compared to the free ciprofloxacin solution. Interestingly, liposomal ciprofloxacin formulations successfully controlled the release of the drug in the epithelial cell model and showed different drug transport profiles on H441 cell lines compared to the free ciprofloxacin solution, supporting the potential for inhaled liposomal ciprofloxacin to provide a promising treatment for respiratory infections.

Nanogels co-loading paclitaxel and curcumin prepared in situ through photopolymerization at 532 nm for synergistically suppressing breast tumors

Combined chemotherapy plays an increasingly important and practical role in the clinical treatment of malignant tumor. In this study, paclitaxel (PTX) and curcumin (Cur) are simultaneously encapsulated into nanogels (termed as NG-PC) in situ by microemulsion photopolymerization at 532 nm for synergistically suppressing breast tumors. NG-PC with a size of 180 nm and a low polydispersity index (PDI < 0.2) presents a controlled and cumulative release of PTX and Cur within 90 h. Moreover, NG-PC displays a remarkable killing effect against 4T1 and MCF-7 cells. In vivo antitumor evaluation on 4T1 tumor-bearing mice demonstrates that NG-PC has significantly higher ability to inhibit tumor growth, inducing necrosis, apoptosis and suppression of proliferation than that of a single drug. Our research provides a facile method to prepare a nano-drug delivery platform with excellent drug co-loading ability and synergistic antitumor effect.

Titanium surface polyethylene glycol hydrogel and gentamicin-loaded cross-linked starch microspheres release system for anti-infective drugs

OBJECTIVE

To design and construct a hydrogel drug-controlled release system loaded with gentamicin on a titanium surface, and to evaluate the in vitro drug release behaviour and antibacterial properties and biocompatibility of the controlled release system.

METHODS

Titanium (Ti) surface was coated with poly dopamine (PDA) substrate, and then polyethylene glycol (PEG) was attached to PDA. The composite drug microsphere controlled release layer formed by gentamicin (GEN) and cross-linked starch (CSt) were subsequently covered with poly lactic⁃co⁃glycolic acid (PLGA) as a barrier to construct a Ti-GEN-Cst-PLGA anti-infective drug controlled release system.

RESULTS

The hydrogel drug release system was successfully constructed. The results of in vitro anti-staphylococcus aureus (SAU) assay, anti-staphylococcus epidermidis (SEP) assay and anti-Escherichia coli (ECO) assay showed that Ti-GEN-Cst-PLGA could effectively inhibit the growth of three bacteria. Assay in the New Zealand rabbit found that Ti-GEN-Cst-PLGA could promote wound healing at the 3rd week after implantation, and the pathology assay found that the Ti-GEN-Cst-PLGA group had less inflammatory reactions and significant tissue proliferation at the endophyte contact surface.

CONCLUSION

Ti-GEN-Cst-PLGA can effectively inhibit the inflammatory response and promote wound healing, or may be a potential treatment for orthopaedic endophytes.

Inhalable microparticles as drug delivery systems to the lungs in a dry powder formulations

Inhalation-administrated drugs remain an interesting possibility of addressing pulmonary diseases. Direct drug delivery to the lungs allows one to obtain high concentration in the site of action with limited systemic distribution, leading to a more effective therapy with reduced required doses and side effects. On the other hand, there are several difficulties in obtaining a formulation that would meet all the criteria related to physicochemical, aerodynamic and biological properties, which is the reason why only very few of the investigated systems can reach the clinical trial phase and proceed to everyday use as a result. Therefore, we focused on powders consisting of polysaccharides, lipids, proteins or natural and synthetic polymers in the form of microparticles that are delivered by inhalation to the lungs as drug carriers. We summarized the most common trends in research today to provide the best dry powders in the right fraction for inhalation that would be able to release the drug before being removed by natural mechanisms. This review article addresses the most common manufacturing methods with novel modifications, pros and cons of different materials, drug loading capacities with release profiles, and biological properties such as cytocompatibility, bactericidal or anticancer properties.

Antimicrobial Activity of Azithromycin Encapsulated into PLGA NPs: A Potential Strategy to Overcome Efflux Resistance

Antimicrobial resistance represents a public health problem with a major negative impact on health and socioeconomic development, and is one of the biggest threats in the modern era. This requires the discovery of new approaches to control microbial infections. Nanomedicine could be one of the promising strategies to improve the treatment of microbial infections. Polymer nanoparticles (PNPs) were reported to overcome the efflux-resistant mechanism toward chemotherapeutic agents. However, to the best of our knowledge, no studies were performed to explore their ability to overcome the efflux-resistant mechanism in bacteria. In the current study, azithromycin (AZI), a macrolide antibiotic, was encapsulated into a biocompatible polymer, poly (lactic-co-glycolic acid) (PLGA) using the nano-precipitation method. The effect of the drug to polymer ratio, surfactant, and pH of the aqueous medium on particle size and drug loading percentage (DL%) were investigated in order to maximize the DL% and control the size of NPs to be around 100 nm. The antibacterial activity of AZI-PLGA NPs was investigated against AZI-resistant bacteria; Methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis (E. faecalis), where the efflux mechanism was demonstrated to be one of the resistant mechanisms. AZI-PLGA NPs were safer than free AZI, as revealed from the cytotoxicity test, and were able to overcome the efflux-resistant mechanism, as revealed by decreasing the MIC of AZI-PLGA NPs by four times than free AZI. The MIC value reduced from 256 to 64 µg/mL and from >1000 to 256 µg/mL for MRSA and E. faecalis, respectively. Therefore, encapsulation of AZI into PNPs was shown to be a promising strategy to overcome the efflux-resistant mechanism towards AZI and improve its antibacterial effect. However, future investigations are necessary to explore the effect (if any) of particle size, surface charge, and material composition of PNPs on antibacterial activity. Moreover, it is essential to ascertain the safety profiles of these PNPs, the possibility of their large-scale manufacture, and if this concept could be extended to other antibiotics.

Managing Apoptosis in Lung Diseases using Nano-assisted Drug Delivery System

Several factors exist that limit the efficacy of lung cancer treatment. These may be tumor-specific delivery of therapeutics, airway geometry, humidity, clearance mechanisms, presence of lung diseases, and therapy against tumor cell resistance. Advancements in drug delivery using nanotechnology based multifunctional nanocarriers, have emerged as a viable method for treating lung cancer with more efficacy and fewer adverse effects. This review does a thorough and critical examination of effective nano-enabled approaches for lung cancer treatment, such as nano-assisted drug delivery systems. In addition, to therapeutic effectiveness, researchers have been working to determine several strategies to produce nanotherapeutics by adjusting the size, drug loading, transport, and retention. Personalized lung tumor therapies using sophisticated nano modalities have the potential to provide great therapeutic advantages based on individual unique genetic markers and disease profiles. Overall, this review provides comprehensive information on newer nanotechnological prospects for improving the management of apoptosis in lung cancer.

Nanoparticle-Based Inhalation Therapy for Pulmonary Diseases

The lung is exposed to various pollutants and is the primary site for the onset of various diseases, including infections, allergies, and cancers. One possible treatment approach for such pulmonary diseases involves direct administration of therapeutics to the lung so as to maintain the topical concentration of the drug. Particles with nanoscale diameters tend to reach the pulmonary region. Nanoparticles (NPs) have garnered significant interest for applications in biomedical and pharmaceutical industries because of their unique physicochemical properties and biological activities. In this article, we describe the biological and pharmacological activities of NPs as well as summarize their potential in the formulation of drugs employed to treat pulmonary diseases. Recent advances in the use of NPs in inhalation chemotherapy for the treatment of lung diseases have also been highlighted.

Differential Performance and Lung Deposition of Levofloxacin with Different Nebulisers Used in Cystic Fibrosis

We compared the performance and levofloxacin (Quinsair) lung deposition of three nebulisers commonly used in CF (I-Neb Advance, eFlow rapid, and LC Plus) with the approved nebuliser Zirela. The delivered dose, delivery rate, and aerosol particle size distribution (APSD) for each device were determined using the methods described in the Pharmacopeia. High-resolution computed tomography scans obtained from seven adult patients with mild CF were used to generate computer-aided, three-dimensional models of their airway tree to assess lung deposition using functional respiratory imaging (FRI). The eFlow rapid and the LC Plus showed poor delivery efficiencies due to their high residual volumes. The I-Neb, which only delivers aerosols during the inspiratory phase, achieved the highest aerosol delivery efficiency. However, the I-Neb showed the largest particle size and lowest delivery rate (2.9 mg/min), which were respectively associated with a high extrathoracic deposition and extremely long nebulisation times (>20 min). Zirela showed the best performance considering delivery efficiency (159.6 mg out of a nominal dose of 240 mg), delivery rate (43.5 mg/min), and lung deposition (20% of the nominal dose), requiring less than 5 min to deliver a full dose of levofloxacin. The present study supports the use of drug-specific nebulisers and discourages the off-label use of general-purpose devices with the present levofloxacin formulation since subtherapeutic lung doses and long nebulisation times may compromise treatment efficacy and adherence.

Hyaluronan-colistin conjugates: Synthesis, characterization, and prospects for medical applications

The development of nanotechnology-based antibiotic delivery systems (nanoantibiotics) is an important challenge in the effort to combat microbial multidrug resistance. These systems have improved biopharmaceutical characteristics by increasing local bioavailability and reducing systemic toxicity and the number and frequency of drug side effects. Conjugation of low -molecular -weight antibacterial agents with natural polysaccharides is an effective strategy for developing optimal targeted delivery systems with programmed release and reduced cytotoxicity. This study describes the synthesis of conjugates of colistin (CT) and hyaluronic acid (HA) using carbodiimide chemistry to conjugate the amino groups of CT with the carboxyl groups of HA. The obtained polysaccharide carriers had a degree of substitution (DS) with CT molecules of 3-10 %, and the CT content was 129-377 μg/mg. The size of the fabricated particles was 300-600 nm; in addition, there were conjugates in the form of single macromolecules (30-50 nm). The ζ-potential of developed systems was about -20 mV. In vitro release studies at pH 7.4 and pH 5.2 showed slow hydrolysis of amide bonds, with a CT release of 1-5 % after 24 h. The conjugates retained antimicrobial activity depending on the DS: at DS 8 %, the minimum inhibitory concentration (MIC) of the conjugate corresponded to the MIC of free CT. The resulting systems also reduced CT nephrotoxicity by 20-50 %. These new conjugates of CT with HA are promising for the development of nanodrugs for safe and effective antimicrobial therapy.

Functionalized Erythrocyte Membrane-Coated Nanoparticles for the Treatment of Klebsiella pneumoniae-Induced Sepsis

Sepsis is a systemic inflammatory response syndrome caused by infection, with high incidence and mortality. Therefore, it is necessary to carry out an effective anti-infection treatment. In this work, we designed and synthesized red blood cell (RBC) membrane-coated PLGA nanoparticles named γ3-RBCNPs, which target the highly expressed intercellular adhesion molecule-1 (ICAM-1) at the site of infection through the γ3 peptide on its surface and kill the Klebsiella pneumoniae through ciprofloxacin encapsulated in its core. In addition, the homogenous RBC membrane coated on the surface of the nanoparticles helps them avoid immune surveillance and prolong the circulation time of the drug in the body. We found that the γ3-RBCNPs target human umbilical vein endothelial cells (HUVECs) activated by TNF-α in vitro and the infected lung of mice in the sepsis model very well. In vitro evaluation suggested that γ3-RBCNPs have a low risk of acute hemolysis and are less likely to be engulfed by macrophages. In vivo evaluation showed that γ3-RBCNPs has a long half-life and good bio-safety. More importantly, we confirmed that γ3-RBCNPs have the good antibacterial and anti-infection ability in vivo and in vitro. Our research provides a new strategy for the nano-drug treatment of Klebsiella pneumoniae-induced sepsis.

Nano-in-Microparticles for Aerosol Delivery of Antibiotic-Loaded, Fucose-Derivatized, and Macrophage-Targeted Liposomes to Combat Mycobacterial Infections: In Vitro Deposition, Pulmonary Barrier Interactions, and Targeted Delivery

Nontuberculous mycobacterial infections rapidly emerge and demand potent medications to cope with resistance. In this context, targeted loco-regional delivery of aerosol medicines to the lungs is an advantage. However, sufficient antibiotic delivery requires engineered aerosols for optimized deposition. Here, the effect of bedaquiline-encapsulating fucosylated versus nonfucosylated liposomes on cellular uptake and delivery is investigated. Notably, this comparison includes critical parameters for pulmonary delivery, i.e., aerosol deposition and the noncellular barriers of pulmonary surfactant (PS) and mucus. Targeting increases liposomal uptake into THP-1 cells as well as peripheral blood monocyte- and lung-tissue derived macrophages. Aerosol deposition in the presence of PS, however, masks the effect of active targeting. PS alters antibiotic release that depends on the drug's hydrophobicity, while mucus reduces the mobility of nontargeted more than fucosylated liposomes. Dry-powder microparticles of spray-dried bedaquiline-loaded liposomes display a high fine particle fraction of >70%, as well as preserved liposomal integrity and targeting function. The antibiotic effect is maintained when deposited as powder aerosol on cultured Mycobacterium abscessus. When treating M. abscessus infected THP-1 cells, the fucosylated variant enabled enhanced bacterial killing, thus opening up a clear perspective for the improved treatment of nontuberculous mycobacterial infections.

A roadmap to pulmonary delivery strategies for the treatment of infectious lung diseases

Pulmonary drug delivery is a highly attractive topic for the treatment of infectious lung diseases. Drug delivery via the pulmonary route offers unique advantages of no first-pass effect and high bioavailability, which provides an important means to deliver therapeutics directly to lung lesions. Starting from the structural characteristics of the lungs and the biological barriers for achieving efficient delivery, we aim to review literatures in the past decade regarding the pulmonary delivery strategies used to treat infectious lung diseases. Hopefully, this review article offers new insights into the future development of therapeutic strategies against pulmonary infectious diseases from a delivery point of view.

Combination and nanotechnology based pharmaceutical strategies for combating respiratory bacterial biofilm infections

Respiratory infections are one of the major global health problems. Among them, chronic respiratory infections caused by biofilm formation are difficult to treat because of both drug tolerance and poor drug penetration into the complex biofilm structure. A major part of the current research on combating respiratory biofilm infections have been focused on destroying the matrix of extracellular polymeric substance and eDNA of the biofilm or promoting the penetration of antibiotics through the extracellular polymeric substance via delivery technologies in order to kill the bacteria inside. There are also experimental data showing that certain inhaled antibiotics with simple formulations can effectively penetrate EPS to kill surficially located bacteria and centrally located dormant bacteria or persisters. This article aims to review recent advances in the pharmaceutical strategies for combating respiratory biofilm infections with a focus on nanotechnology-based drug delivery approaches. The formation and characteristics of bacterial biofilm infections in the airway mucus are presented, which is followed by a brief review on the current clinical approaches to treat respiratory biofilm infections by surgical removal and antimicrobial therapy, and also the emerging clinical treatment approaches. The current combination of antibiotics and non-antibiotic adjuvants to combat respiratory biofilm infections are also discussed.

Transferring Microclusters of P. aeruginosa Biofilms to the Air-Liquid Interface of Bronchial Epithelial Cells for Repeated Deposition of Aerosolized Tobramycin

As an alternative to technically demanding and ethically debatable animal models, the use of organotypic and disease-relevant human cell culture models may improve the throughput, speed, and success rate for the translation of novel anti-infectives into the clinic. Besides bacterial killing, host cell viability and barrier function appear as relevant but seldomly measured readouts. Moreover, bacterial virulence factors and signaling molecules are typically not addressed in current cell culture models. Here, we describe a reproducible protocol for cultivating barrier-forming human bronchial epithelial cell monolayers on Transwell inserts and infecting them with microclusters of pre-grown mature Pseudomonas aeruginosa PAO1 biofilms under the air-liquid interface conditions. Bacterial growth and quorum sensing molecules were determined upon tobramycin treatment. The host cell response was simultaneously assessed through cell viability, epithelial barrier function, and cytokine release. By repeated deposition of aerosolized tobramycin after 1, 24, and 48 h, bacterial growth was controlled (reduction from 10 to 4 log₁₀ CFU/mL), which leads to epithelial cell survival for up to 72 h. E-cadherin's cell-cell adhesion protein expression was preserved with the consecutive treatment, and quorum sensing molecules were reduced. However, the bacteria could not be eradicated and epithelial barrier function was impaired, similar to the currently observed situation in the clinic in lack of more efficient anti-infective therapies. Such a human-based in vitro approach has the potential for the preclinical development of novel anti-infectives and nanoscale delivery systems for oral inhalation.

Design and evaluation of folate-modified liposomes for pulmonary administration in lung cancer therapy

Pulmonary drug administration for the treatment of lung cancer is useful because the drug is directly delivered to the lung tissues with minimal invasiveness and higher efficiency compared to other conventional methods. However, it is critical to enhance drug accumulation in the lung cancer tissues to achieve sufficient therapeutic efficacy. The submicron-sized liposome (ssLip) preparation is one of the most promising approaches to enhance drug accumulation in the lungs; however, ssLips prepared for conventional inhalation do not have tumour selectivity. Therefore, in this study, we prepared folate (FA)-modified ssLip (FA-ssLip) to enhance drug accumulation in folate receptor (FR)-expressing lung cancer cells, and evaluated its physicochemical properties and potential as a drug carrier in pulmonary administration. In addition, we prepared rapamycin (RM-an autophagy-inducing anticancer drug)-loaded FA-ssLip (RM/FA-ssLip) and investigated its anti-tumour effect. FA-ssLip showed excellent nanoparticle properties with submicron size (approximately 120 nm) and high lung accumulation in lung cancer mouse model-bearing LL2 cells-a mouse Lewis lung carcinoma cell line. RM/FA-ssLip showed significant cytotoxic activity in FR-expressing cancer cells. In addition, pulmonary administration of RM/FA-ssLip extended the survival of LL2 cell tumour-bearing mice. Taken together, our results suggest the potential of FA-ssLip as a pulmonary drug carrier for the efficient treatment of lung cancer.

Developing ciprofloxacin dry powder for inhalation: A story of challenges and rational design in the treatment of cystic fibrosis lung infection

Cystic fibrosis (CF) is an inherited multisystem disease affecting the lung which leads to a progressive decline in lung function as a result of malfunctioning mucociliary clearance and subsequent chronic bacterial infections. Pseudomonas aeruginosa is the predominant cause of lung infection in CF patients and is associated with significant morbidity and mortality. Thus, antibiotic therapy remains the cornerstone of the treatment of CF. Pulmonary delivery of antibiotics for lung infections significantly reduces the required dose and the associated systemic side effects while improving therapeutic outcomes. Ciprofloxacin is one of the most widely used antibiotics against P. aeruginosa and the most effective fluoroquinolone. However, in spite of the substantial amount of research aimed at developing ciprofloxacin powder for inhalation, none of these formulations has been commercialized. Here, we present an integrated view of the diverse challenges associated with delivering ciprofloxacin dry particles to the lungs of CF patients and the rationales behind recent formulations of ciprofloxacin dry powder for inhalation. This review will discuss the challenges in developing ciprofloxacin powder for inhalation along with the physiological and pathophysiological challenges such as ciprofloxacin lung permeability, overproduction of viscous mucus and bacterial biofilms. The review will also discuss the current and emerging particle engineering approaches to overcoming these challenges. By doing so, we believe the review will help the reader to understand the current limitations in developing an inhalable ciprofloxacin powder and explore new opportunities of rational design strategies.

Deposition of Inhaled Levofloxacin in Cystic Fibrosis Lungs Assessed by Functional Respiratory Imaging

Pulmonary infections caused by Pseudomonas aeruginosa (PA) represent the leading cause of pulmonary morbidity in adults with cystic fibrosis (CF). In addition to tobramycin, colistin, and aztreonam, levofloxacin has been approved in Europe to treat PA infections. Nevertheless, no lung deposition data on inhaled levofloxacin are yet available. We conducted a Functional Respiratory Imaging (FRI) study to predict the lung deposition of levofloxacin in the lungs of patients with CF. Three-dimensional airway models were digitally reconstructed from twenty high-resolution computed tomography scans obtained from historical patients' records. Levofloxacin aerosols generated with the corresponding approved nebuliser were characterised according to pharmacopeia. The obtained data were used to inform a computational fluid dynamics simulation of levofloxacin lung deposition using breathing patterns averaged from actual CF patients' spirometry data. Levofloxacin deposition in the lung periphery was significantly reduced by breathing patterns with low inspiratory times and high inspiratory flow rates. The intrathoracic levofloxacin deposition percentages for moderate and mild CF lungs were, respectively, 37.0% ± 13.6 and 39.5% ± 12.9 of the nominal dose. A significant albeit modest correlation was found between the central-to-peripheral deposition (C/P) ratio of levofloxacin and FEV1. FRI analysis also detected structural differences between mild and moderate CF airways. FRI revealed a significant intrathoracic deposition of levofloxacin aerosols, which distributed preferentially to the lower lung lobes, with an influence of the deterioration of FEV1 on the C/P ratio. The three-dimensional rendering of CF airways also detected structural differences between the airways of patients with mild and moderate CF.

The Application of Metagenomic Next-Generation Sequencing in Detection of Pathogen in Bronchoalveolar Lavage Fluid and Sputum Samples of Patients with Pulmonary Infection

Objective

To uncover the application value of metagenomic next-generation sequencing (mNGS) in the detection of pathogen in bronchoalveolar lavage fluid (BALF) and sputum samples.

Methods

Totally, 32 patients with pulmonary infection were included. Pathogens in BALF and sputum samples were tested simultaneously by routine microbial culture and mNGS. Main infected pathogens (bacteria, fungi, and viruses) and their distribution in BALF and sputum samples were analyzed. Moreover, the diagnostic performance of mNGS in paired BALF and sputum samples was assessed.

Results

The pathogen culture results were positive in 9 patients and negative in 13 patients. No statistical differences were recorded on the sensitivity (78.94% vs. 63.15%, p = 0.283) and specificity (62.50% vs. 75.00%, p = 0.375) of mNGS diagnosis in bacteria and fungus in two types of samples. As shown in mNGS detection, 10 patients' two samples were both positive, 13 patients' two samples were both negative, 7 patients were only positive in BALF samples, and 2 patients' sputum samples were positive. Main viruses mNGS detected were EB virus, human adenovirus 5, herpes simplex virus type 1, and human cytomegalovirus. Kappa consensus analysis indicated that mNGS showed significant consistency in detecting pathogens in two samples, no matter bacteria (p < 0.001), fungi (p = 0.026), or viruses (p = 0.008).

Conclusion

mNGS showed no statistical differences in sensitivity and specificity of pathogen detection in BALF and sputum samples. Under certain conditions, sputum samples might be more suitable for pathogen detection because of invasiveness of BALF samples.

Nanomedicine to advance the treatment of bacteria-induced acute lung injury

Bacteria-induced acute lung injury (ALI) is associated with a high mortality rate due to the lack of an effective treatment. Patients often rely on supportive care such as low tidal volume ventilation to alleviate the symptoms. Nanomedicine has recently received much attention owing to its premium benefits of delivering drugs in a sustainable and controllable manner while minimizing the potential side effects. It can effectively improve the prognosis of bacteria-induced ALI through targeted delivery of drugs, regulation of multiple inflammatory pathways, and combating antibiotic resistance. Hence, in this review, we first discuss the pathogenesis of ALI and its potential therapeutics. In particular, the state-of-the-art nanomedicines for the treatment of bacteria-induced ALI are highlighted, including their administration routes, in vivo distribution, and clearance. Furthermore, the available bacteria-induced ALI animal models are also summarized. In the end, future perspectives of nanomedicine for ALI treatment are proposed.

Preclinical Evaluation of Inhalational Spectinamide-1599 Therapy against Tuberculosis

The lengthy treatment time for tuberculosis (TB) is a primary cause for the emergence of multidrug resistant tuberculosis (MDR-TB). One approach to improve TB therapy is to develop an inhalational TB therapy that when administered in combination with oral TB drugs eases and shortens treatment. Spectinamides are new semisynthetic analogues of spectinomycin with excellent activity against Mycobacterium tuberculosis (Mtb), including MDR and XDR Mtb strains. Spectinamide-1599 was chosen as a promising candidate for development of inhalational therapy. Using the murine TB model and intrapulmonary aerosol delivery of spectinamide-1599, we characterized the pharmacokinetics and efficacy of this therapy in BALB/c and C3HeB/FeJ mice infected with the Mtb Erdman strain. As expected, spectinamide-1599 exhibited dose-dependent exposure in plasma, lungs, and ELF, but exposure ratios between lung and plasma were 12-40 times higher for intrapulmonary compared to intravenous or subcutaneous administration. In chronically infected BALB/c mice, low doses (10 mg/kg) of spectinamide-1599 when administered thrice weekly for two months provide efficacy similar to that of higher doses (50-100 mg/kg) after one month of therapy. In the C3HeB/FeJ TB model, intrapulmonary aerosol delivery of spectinamide-1599 (50 mg/kg) or oral pyrazinamide (150 mg/kg) had limited or no efficacy in monotherapy, but when both drugs were given in combination, a synergistic effect with superior bacterial reduction of >1.8 log₁₀ CFU was observed. Throughout the up to eight-week treatment period, intrapulmonary therapy was well-tolerated without any overt toxicity. Overall, these results strongly support the further development of intrapulmonary spectinamide-1599 as a combination partner for anti-TB therapy.

Nanomedicine as a promising strategy for the theranostics of infectious diseases

Infectious diseases caused by bacteria, viruses, and fungi and their global spread pose a great threat to human health. The 2019 World Health Organization report predicted that infection-related mortality will be similar to cancer mortality by 2050. Particularly, the global cumulative numbers of the recent outbreak of coronavirus disease (COVID-19) have reached 110.7 million cases and over 2.4 million deaths as of February 23, 2021. Moreover, the crisis of these infectious diseases exposes the many problems of traditional diagnosis, treatment, and prevention, such as time-consuming and unselective detection methods, the emergence of drug-resistant bacteria, serious side effects, and poor drug delivery. There is an urgent need for rapid and sensitive diagnosis as well as high efficacy and low toxicity treatments. The emergence of nanomedicine has provided a promising strategy to greatly enhance detection methods and drug treatment efficacy. Owing to their unique optical, magnetic, and electrical properties, nanoparticles (NPs) have great potential for the fast and selective detection of bacteria, viruses, and fungi. NPs exhibit remarkable antibacterial activity by releasing reactive oxygen species and metal ions, exerting photothermal effects, and causing destruction of the cell membrane. Nano-based delivery systems can further improve drug permeability, reduce the side effects of drugs, and prolong systemic circulation time and drug half-life. Moreover, effective drugs against COVID-19 are still lacking. Recently, nanomedicine has shown great potential to accelerate the development of safe and novel anti-COVID-19 drugs. This article reviews the fundamental mechanisms and the latest developments in the treatment and diagnosis of bacteria, viruses, and fungi and discusses the challenges and perspectives in the application of nanomedicine.