Overcoming resistance: Chitosan-modified liposomes as targeted drug carriers in the fight against multidrug resistant bacteria-a review

Antimicrobial resistance (AMR) poses a significant global health threat, rendering standard antibiotics ineffective against multi-drug resistant bacteria. To tackle this urgent issue, innovative approaches are essential. Liposomes, small spherical vesicles made of a phospholipid bilayer, present a promising solution. These vesicles can encapsulate various medicines and are both biocompatible and biodegradable. Their ability to be modified for targeted tissue or cell uptake makes them an ideal drug delivery system. By delivering antibiotics directly to infection sites, liposomes minimize side effects and reduce the development of resistance. However, challenges such as poor stability and rapid drug leakage limit their biological application. Chitosan, a biocompatible polymer, enhances liposome interaction with specific tissues or cells, enabling selective drug release at infection sites. Incorporating chitosan into liposome formulations alters and diversifies their surface characteristics through electrostatic interactions, resulting in improved stability and pH-sensitive drug release. These interactions are crucial for enhancing drug retention and targeted delivery, especially in varying pH environments like tumor sites or infection areas, thereby improving therapeutic outcomes and reducing systemic side effects. This review discusses recent advancements, challenges, and the need for further research to optimize liposome formulations and enhance targeted drug delivery for effective AMR treatment. Chitosan-modified liposomes offer a promising strategy to overcome AMR and improve antimicrobial therapies.

Nanomedicines via the pulmonary route: a promising strategy to reach the target?

Over the past decades, research on nanomedicines as innovative tools in combating complex pathologies has increased tenfold, spanning fields from infectiology and ophthalmology to oncology. This process has further accelerated since the introduction of SARS-CoV-2 vaccines. When it comes to human health, nano-objects are designed to protect, transport, and improve the solubility of compounds to allow the delivery of active ingredients on their targets. Nanomedicines can be administered by different routes, such as intravenous, oral, intramuscular, or pulmonary routes. In the latter route, nanomedicines can be aerosolized or nebulized to reach the deep lung. This review summarizes existing nanomedicines proposed for inhalation administration, from their synthesis to their potential clinical use. It also outlines the respiratory organs, their structure, and particularities, with a specific emphasis on how these factors impact the administration of nanomedicines. Furthermore, the review addresses the organs accessible through pulmonary administration, along with various pathologies such as infections, genetic diseases, or cancer that can be addressed through inhaled nanotherapeutics. Finally, it examines the existing devices suitable for the aerosolization of nanomedicines and the range of nanomedicines in clinical development.

Lentisk (Pistacia lentiscus) Oil Nanoemulsions Loaded with Levofloxacin: Phytochemical Profiles and Antibiofilm Activity against Staphylococcus spp

Most clinical isolates of both Staphylococcus aureus and Staphylococcus epidermidis show the capacity to adhere to abiotic surfaces and to develop biofilms resulting in a contribution to chronic human skin infections. Antibiotic resistance and poor biofilm penetration are the main causes of ineffective therapeutic treatment in killing bacteria within biofilms. A possible strategy could be represented by drug delivery systems, such as nanoemulsions (composed of bioactive oil, surfactant and water phase), which are useful for enhancing the drug permeation of a loaded drug inside the biofilm and its activity. Phytochemical characterization of Pistacia lentiscus oil (LO) by direct infusion Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) allowed the identification of bioactive compounds with antimicrobial properties, including fatty acids and phenolic compounds. Several monoterpenes and sesquiterpenes have been also detected and confirmed by gas chromatography-mass spectrometric (GC-MS) analysis, together providing a complete metabolomic profiling of LO. In the present study, a nanoemulsion composed of LO has been employed for improving Levofloxacin water solubility. A deep physical-chemical characterization of the nanoemulsion including hydrodynamic diameter, ζ-potential, morphology, entrapment efficiency, stability release and permeation studies was performed. Additionally, the antimicrobial/antibiofilm activity of these preparations was evaluated against reference and clinical Staphylococcus spp. strains. In comparison to the free-form antibiotic, the loaded NE nanocarriers exhibited enhanced antimicrobial activity against the sessile forms of Staphylococcus spp. strains.

Lipid sulfoxide polymers as potential inhalable drug delivery platforms with differential albumin binding affinity

Inhalable nanomedicines are increasingly being developed to optimise the pharmaceutical treatment of respiratory diseases. Large lipid-based nanosystems at the forefront of the inhalable nanomedicines development pipeline, though, have a number of limitations. The objective of this study was, therefore, to investigate the utility of novel small lipidated sulfoxide polymers based on poly(2-(methylsulfinyl)ethyl acrylate) (PMSEA) as inhalable drug delivery platforms with tuneable membrane permeability imparted by differential albumin binding kinetics. Linear PMSEA (5 kDa) was used as a hydrophilic polymer backbone with excellent anti-fouling and stealth properties compared to poly(ethylene glycol). Terminal lipids comprising single (1C2, 1C12) or double (2C12) chain diglycerides were installed to provide differing affinities for albumin and, by extension, albumin trafficking pathways in the lungs. Albumin binding kinetics, cytotoxicity, lung mucus penetration and cellular uptake and permeability through key cellular barriers in the lungs were examined in vitro. The polymers showed good mucus penetration and no cytotoxicity over 24 h at up to 1 mg ml-1. While 1C2-showed no interaction with albumin, 1C12-PMSEA and 2C12-PMSEA bound albumin with KD values of approximately 76 and 10 μM, respectively. Despite binding to albumin, 2C12-PMSEA showed reduced cell uptake and membrane permeability compared to the smaller polymers and the presence of albumin had little effect on cell uptake and membrane permeability. While PMSEA strongly shielded these lipids from albumin, the data suggest that there is scope to tune the lipid component of these systems to control membrane permeability and cellular interactions in the lungs to tailor drug disposition in the lungs.

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.

Hydrogenated Soy Phosphatidylcholine Liposomes Stimulate Differential Expression of Chemokines And Cytokines by Rat Alveolar Macrophages In Vitro

Liposomes are being developed as inhalable drug delivery systems, but concerns remain about their impact on the lungs. To better understand the impact of liposomes and their physicochemical properties on alveolar macrophages, the cytokine and chemokine expression profile of rat alveolar Nr8383 macrophages exposed to 0.1 and 1 mg/ml hydrogenated soy phosphatidylcholine (HSPC) liposomes was examined. Expression patterns varied considerably between liposomes in a concentration-dependent manner, with both anti- and pro-inflammatory chemokines/cytokines produced. Uncharged liposomes induce the greatest production of cytokines and chemokines, followed by PEGylated liposomes. The most significant increase in cytokine/chemokine expression was seen for IL-2 (up to 24-fold), IL-4 (up to 5-fold), IL-18 and VEGF (up to 10-fold), while liposome exposure significantly reduced MIP1 expression (5-fold). In summary, we demonstrate that liposome surface properties promote variable patterns of cytokine and chemokine secretion by alveolar macrophages. This suggests that the type of liposome employed may influence the type of immune response generated in the lung and by extension, dictate how inhaled liposomal nanomedicines affect the lungs response to inhaled toxicants and local infections.

Enzyme-Linked Lipid Nanocarriers for Coping Pseudomonal Pulmonary Infection. Would Nanocarriers Complement Biofilm Disruption or Pave Its Road?

Introduction

Cystic fibrosis (CF) is associated with pulmonary Pseudomonas aeruginosa infections persistent to antibiotics.

Methods

To eradicate pseudomonal biofilms, solid lipid nanoparticles (SLNs) loaded with quorum-sensing-inhibitor (QSI, disrupting bacterial crosstalk), coated with chitosan (CS, improving internalization) and immobilized with alginate lyase (AL, destroying alginate biofilms) were developed.

Results

SLNs (140-205 nm) showed prolonged release of QSI with no sign of acute toxicity to A549 and Calu-3 cells. The CS coating improved uptake, whereas immobilized-AL ensured >1.5-fold higher uptake and doubled SLN diffusion across the artificial biofilm sputum model. Respirable microparticles comprising SLNs in carbohydrate matrix elicited aerodynamic diameters MMAD (3.54, 2.48 µm) and fine-particle-fraction FPF (65, 48%) for anionic and cationic SLNs, respectively. The antimicrobial and/or antibiofilm activity of SLNs was explored in Pseudomonas aeruginosa reference mucoid/nonmucoid strains as well as clinical isolates. The full growth inhibition of planktonic bacteria was dependent on SLN type, concentration, growth medium, and strain. OD measurements and live/dead staining proved that anionic SLNs efficiently ceased biofilm formation and eradicated established biofilms, whereas cationic SLNs unexpectedly promoted biofilm progression. AL immobilization increased biofilm vulnerability; instead, CS coating increased biofilm formation confirmed by 3D-time lapse confocal imaging. Incubation of SLNs with mature biofilms of P. aeruginosa isolates increased biofilm density by an average of 1.5-fold. CLSM further confirmed the binding and uptake of the labeled SLNs in P. aeruginosa biofilms. Considerable uptake of CS-coated SLNs in non-mucoid strains could be observed presumably due to interaction of chitosan with LPS glycolipids in the outer cell membrane of P. aeruginosa.

Conclusion

The biofilm-destructive potential of QSI/SLNs/AL inhalation is promising for site-specific biofilm-targeted interventional CF therapy. Nevertheless, the intrinsic/extrinsic fundamentals of nanocarrier-biofilm interactions require further investigation.

Liposomes for Inhalation

Inhalation of liposomes formulated with phospholipids similar to endogenous lung surfactants and lipids offers biocompatibility and versatility within the pulmonary medicine field to treat a range of diseases such as lung cancer, cystic fibrosis and lung infections. Manipulation of the physicochemical properties of liposomes enables innovative design of the carrier to meet specific delivery, release and targeting requirements. This delivery system offers several benefits: improved pharmacokinetics with reduced toxicity, enhanced therapeutic efficacy, increased delivery of poorly soluble drugs, taste masking, biopharmaceutics degradation protection and targeted cellular therapy. This section provides an overview of liposomal formulation and delivery, together with their applications for different disease states in the lung.

Phage cocktails - an emerging approach for the control of bacterial infection with major emphasis on foodborne pathogens

Phage therapy has recently attracted a great deal of attention to counteract the rapid emergence of antibiotic-resistant bacteria. In comparison to monophage therapy, phage cocktails are typically used to treat individual and/or multi-bacterial infections since the bacterial agents are unlikely to become resistant as a result of exposure to multiple phages simultaneously. The bacteriolytic effect of phage cocktails may produce efficient killing effect in comparison to individual phage. However, multiple use of phages (complex cocktails) may lead to undesirable side effects such as dysbiosis, horizontal gene transfer, phage resistance, cross resistance, and/or higher cost of production. Cocktail formulation, therefore, representa compromise between limiting the complexity of the cocktail and achieving substantial bacterial load reduction towards the targeted host organisms. Despite some constraints, the applications of monophage therapy have been well documented in the literature. However, phage cocktails-based approaches and their role for the control of pathogens have not been well investigated. In this review, we discuss the principle of phage cocktail formulations, their optimization strategies, major phage cocktail preparations, and their efficacy in inactivating various food borne bacterial pathogens.

The Potentiation Activity of Azithromycin in Combination with Colistin or Levofloxacin Against Pseudomonas aeruginosa Biofilm Infection

Objective

Pseudomonas aeruginosa (PA) often displays drug resistance and biofilm-mediated adaptability. Here, we aimed to evaluate the antibiofilm efficacy of azithromycin-based combination regimens.

Methods

Minimum inhibitory concentrations (MICs), minimal biofilm eradication concentrations (MBECs), and MBEC-combination of azithromycin, colistin, amikacin, and levofloxacin to bioluminescent strain PAO1 and carbapenem-resistant PAO1 (CRPAO1) were assessed. An animal biofilm infection model was established and detected using a live animal bio-photonic imaging system.

Results

In vitro, PAO1 and CRPAO1 were susceptible to colistin, amikacin, and levofloxacin, while they were unsusceptible to azithromycin. The combinations based on azithromycin have no synergistic effect on biofilm in vitro. In vivo, azithromycin plus colistin or levofloxacin could shorten the PAO1 biofilm eradication time, which totally eradicates the biofilm in all mice on the 8th or 6th day, while monotherapy only eradicate biofilm in 70% or 80% mice on the 8th day. For CRPAO1 biofilm, only azithromycin-colistin combination and colistin monotherapy eradicated the bacteria in 60% and 40% of mice at the 6th day.

Conclusion

Azithromycin-based combinations containing levofloxacin or colistin had no synergistic effect in vitro, and they are promising for clinical applications due to the good synergistic activity against PAO1 biofilms in vivo.

Carboxylated Nanoparticle Surfaces Enhance Association with Mucoid Pseudomonas aeruginosa Biofilms

Pseudomonas aeruginosa biofilms comprise three main polysaccharides: alginate, psl, and pel, which all imbue tolerance against exogenous antimicrobials. Nanoparticles (NPs) are an exciting new strategy to overcome the biofilm matrix for therapeutic delivery applications; however, zero existing FDA approvals for biofilm-specific NP formulations can be attributed to the complex interplay of physiochemical forces at the biofilm-NP interface. Here, we leverage a set of inducible, polysaccharide-specific, expressing isogenic P. aeruginosa mutants coupled with an assembled layer-by-layer NP (LbL NP) panel to characterize biofilm-NP interactions. When investigating these interactions using confocal microscopy, alginate-layered NPs associated more than dextran-sulfate-layered NPs with biofilms that had increased alginate production, including biofilms produced by mucoid P. aeruginosa isolates from people with cystic fibrosis. These differences were further confirmed in LbL NPs layered with polysaccharide- or hydrocarbon-based polymers with pendent carboxylate or sulfate functional groups. These data suggest carboxylated NP surfaces have enhanced interactions specifically with mucoid biofilms as compared to sulfated surfaces and lay the foundation for their inclusion as a design element for increasing biofilm-NP interactions and efficacious drug delivery.

Amikacin Liposome Inhalation Suspension in the Real-World Management of Refractory Mycobacterium avium Complex Pulmonary Disease

The increasing prevalence of Mycobacterium avium complex (MAC) pulmonary disease poses a significant therapeutic challenge, particularly due to the limited efficacy and systemic toxicity associated with conventional guideline-based therapy. Amikacin liposome inhalation suspension (ALIS) has been developed, yet its real-world application remains underreported. This retrospective analysis, conducted from March 2021 to February 2024, examined ALIS's clinical use in patients aged 20 years or older with refractory MAC pulmonary disease at our institution. The primary objective of this study is to describe the patient characteristics and clinical trajectories associated with the initiation of ALIS therapy in real-world settings for individuals diagnosed with MAC pulmonary disease. Of 11 patients initiated on ALIS, one was excluded due to financial constraints impacting continuation. The analysis proceeded with the remaining 10 subjects. The mean age of participants was 70.2 years, with a predominance of female patients (n = 7, 70%) and a higher incidence of M. avium infections (n = 6, 60%). Forty percent of the cohort (n = 4) had a history of ethambutol-induced optic neuritis leading to the cessation of the drug. The average interval from the initiation of guideline-based therapy to the start of ALIS was 8.5 ± 6.9 years (mean ± standard deviation). The majority (80%) presented with positive Gaffky scores at ALIS initiation, and a significant proportion exhibited resistance to clarithromycin and ethambutol. Comorbid conditions, including diabetes and previous cancer, were noted. The study also observed elevated anti-MAC antibody levels. Treatment duration varied, with fatigue leading to discontinuation in two cases. Treatment-emergent adverse events were documented in individual patients, each presenting with grade 1 severity: hemoptysis (n = 1, 10%), elevated creatinine levels (n = 1, 10%), and dysphonia (n = 2, 20%) were observed, respectively. Correlation analysis revealed a significant inverse relationship between body mass index (BMI) and ALIS discontinuation due to fatigue, and a positive correlation between Gaffky scores and C-reactive protein (CRP) levels. These results underscore the potential benefits and limitations of ALIS, suggesting that timely intervention and comprehensive healthcare support are crucial for optimal outcomes in the treatment of advanced MAC pulmonary disease.

Lipid-based nanomedicines for the treatment of bacterial respiratory infections: current state and new perspectives

The global threat posed by antimicrobial resistance demands urgent action and the development of effective drugs. Lower respiratory tract infections remain the deadliest communicable disease worldwide, often challenging to treat due to the presence of bacteria that form recalcitrant biofilms. There is consensus that novel anti-infectives with reduced resistance compared with conventional antibiotics are needed, leading to extensive research on innovative antibacterial agents. This review explores the recent progress in lipid-based nanomedicines developed to counteract bacterial respiratory infections, especially those involving biofilm growth; focuses on improved drug bioavailability and targeting and highlights novel strategies to enhance treatment efficacy while emphasizing the importance of continued research in this dynamic field.

Antibacterial and antibiofilm effects of Pseudomonas aeruginosa derived outer membrane vesicles against Streptococcus mutans

Antimicrobial resistance (AMR) is a serious and most urgent global threat to human health. AMR is one of today's biggest difficulties in the health system and has the potential to harm people at any stage of life, making it a severe public health issue. There must be fewer antimicrobial medicines available to treat diseases given the rise in antibiotic-resistant organisms. If no new drugs are created or discovered, it is predicted that there won't be any effective antibiotics accessible by 2050. In most cases, Streptococcus increased antibiotic resistance by forming biofilms, which account for around 80 % of all microbial infections in humans. This highlights the need to look for new strategies to manage diseases that are resistant to antibiotics. Therefore, development alternative, biocompatible and high efficacy new strategies are essential to overcome drug resistance. Recently, bacterial derived extracellular vesicles have been applied to tackle infection and reduce the emergence of drug resistance. Therefore, the objective of the current study was designed to assess the antibacterial and antibiofilm potential of outer membrane vesicles (OMVs) derived from Pseudomonas aeruginosa againstStreptococcus mutans. According to the findings of this investigation, the pure P. aeruginosa outer membrane vesicles (PAOMVs) display a size of 100 nm. S. mutans treated with PAOMVs showed significant antibacterial and antibiofilm activity. The mechanistic studies revealed that PAOMVs induce cell death through excessive generation of reactive oxygen species and imbalance of redox leads to lipid peroxidation, decreased level of antioxidant markers including glutathione, superoxide dismutase and catalase. Further this study confirmed that PAOMVs significantly impairs metabolic activity through inhibiting lactate dehydrogenase activity (LDH), adenosine triphosphate (ATP) production, leakage of proteins and sugars. Interestingly, combination of sub-lethal concentrations of PAOMVs and antibiotics enhances cell death and biofilm formation of S. mutans. Altogether, this work, may serve as an important basis for further evaluation of PAOMVs as novel therapeutic agents against bacterial infections.

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.

Recent advances in nanoparticle applications in respiratory disorders: a review

Various nanoparticles are used in the discovery of new nanomedicine to overcome the shortages of conventional drugs. Therefore, this article presents a comprehensive and up-to-date review of the effects of nanoparticle-based drugs in the treatment of respiratory disorders, including both basic and clinical studies. Databases, including PubMed, Web of Knowledge, and Scopus, were searched until the end of August 2022 regarding the effect of nanoparticles on respiratory diseases. As a new tool, nanomedicine offered promising applications for the treatment of pulmonary diseases. The basic composition and intrinsic characteristics of nanomaterials showed their effectiveness in treating pulmonary diseases. The efficiency of different nanomedicines has been demonstrated in experimental animal models of asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (PF), lung cancer, lung infection, and other lung disorders, confirming their function in the improvement of respiratory disorders. Various types of nanomaterials, such as carbon nanotubes, dendrimers, polymeric nanomaterials, liposomes, quantum dots, and metal and metal oxide nanoparticles, have demonstrated therapeutic effects on respiratory disorders, which may lead to new possible remedies for various respiratory illnesses that could increase drug efficacy and decrease side effects.

Cinchonain Ia Shows Promising Antitumor Effects in Combination with L-Asparaginase-Loaded Nanoliposomes

Cancer is among the leading causes of death worldwide, with no effective and safe treatment to date. This study is the first to co-conjugate the natural compound cinchonain Ia, which has promising anti-inflammatory activity, and L-asparaginase (ASNase), which has anticancer potential, to manufacture nanoliposomal particles (CALs). The CAL nanoliposomal complex had a mean size of approximately 118.7 nm, a zeta potential of -47.00 mV, and a polydispersity index (PDI) of 0.120. ASNase and cinchonain Ia were encapsulated into liposomes with approximately 93.75% and 98.53% efficiency, respectively. The CAL complex presented strong synergistic anticancer potency, with a combination index (CI) < 0.32 in two-dimensional culture and 0.44 in a three-dimensional model, as tested on NTERA-2 cancer stem cells. Importantly, the CAL nanoparticles demonstrated outstanding antiproliferative efficiency on cell growth in NTERA-2 cell spheroids, with greater than 30- and 2.5-fold increases in cytotoxic activity compared to either cinchonain Ia or ASNase liposomes, respectively. CALs also presented extremely enhanced antitumor effects, reaching approximately 62.49% tumor growth inhibition. Tumorized mice under CALs treatment showed a survival rate of 100%, compared to 31.2% in the untreated control group (p < 0.01), after 28 days of the experiment. Thus, CALs may represent an effective material for anticancer drug development.

Perspectives on Usage of Functional Nanomaterials in Antimicrobial Therapy for Antibiotic-Resistant Bacterial Infections

The clinical applications of nanotechnology are emerging as widely popular, particularly as a potential treatment approach for infectious diseases. Diseases associated with multiple drug-resistant organisms (MDROs) are a global concern of morbidity and mortality. The prevalence of infections caused by antibiotic-resistant bacterial strains has increased the urgency associated with researching and developing novel bactericidal medicines or unorthodox methods capable of combating antimicrobial resistance. Nanomaterial-based treatments are promising for treating severe bacterial infections because they bypass antibiotic resistance mechanisms. Nanomaterial-based approaches, especially those that do not rely on small-molecule antimicrobials, display potential since they can bypass drug-resistant bacteria systems. Nanoparticles (NPs) are small enough to pass through the cell membranes of pathogenic bacteria and interfere with essential molecular pathways. They can also target biofilms and eliminate infections that have proven difficult to treat. In this review, we described the antibacterial mechanisms of NPs against bacteria and the parameters involved in targeting established antibiotic resistance and biofilms. Finally, yet importantly, we talked about NPs and the various ways they can be utilized, including as delivery methods, intrinsic antimicrobials, or a mixture.

Formulation and Evaluation of Amikacin Sulfate Loaded Dextran Nanoparticles against Human Pathogenic Bacteria

Amikacin sulfate-loaded dextran sulfate sodium nanoparticles were formulated, lyophilized (LADNP), and then analyzed. The LADNP had a −20.9 ± 8.35 mV zeta potential, PDI of 0.256, and % PDI of 67.7. The zeta average nano size of LADNP was 317.9 z. d.nm, while the dimension of an individual particle was 259.3 ± 73.52 nm, and nanoparticle conductivity in colloidal solution was 2.36 mS/cm. LADNP has distinct endothermic peaks at temperatures at 165.77 °C, according to differential scanning calorimetry (DSC). The thermogravimetric analysis (TGA) showed the weight loss of LADNP, which was observed as 95% at 210.78 °C. XRD investigation on LADNP exhibited distinct peaks at 2θ as 9.6°, 10.4°, 11.4°, 18.9°, 20.3°, 24.4°, 28.2°, 33.2°, 38.9°, and 40.4° confirming crystalline structure. The amikacin release kinetics from LADNP revealed zero order kinetics with a linear release showed zero order kinetics with 37% of drug release in 7 h and had an R2 value of 0.99. The antibacterial effect of LADNP showed broad-spectrum activity against tested human pathogenic bacteria. The preset study demonstrated that LADNP is a promising antibacterial agent.

Colistin- and amikacin-loaded lipid-based drug delivery systems for resistant gram-negative lung and wound bacterial infections

Antimicrobial resistance (AMR) is a global health issue, which needs to be tackled without further delay. The World Health Organization(WHO) has classified three gram-negative bacteria, Pseudomonas aeruginosa, Klebsiella pneumonia and Acinetobacter baumannii, as the principal responsible for AMR, mainly causing difficult to treat nosocomial lung and wound infections. In this regard, the need for colistin and amikacin, the re-emerged antibiotics of choice for resistant gram-negative infections, will be examined as well as their associated toxicity. Thus, current but ineffective clinical strategies designed to prevent toxicity related to colistin and amikacin will be reported, highlighting the importance of lipid-based drug delivery systems (LBDDSs), such as liposomes, solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), as efficient delivery strategies for reducing antibiotic toxicity. This review reveals that colistin- and amikacin-NLCs are promising carriers with greater potential than liposomes and SLNs to safely tackle AMR, especially for lung and wound infections.

Drug delivery as a sustainable avenue to future therapies

Climate change and the need for sustainable, technological developments are the greatest challenges facing humanity in the coming decades. To address these issues, in 2015 the United Nations have established 17 Sustainable Development Goals. Anthropogenic climate change will not only affect everyone personally in the coming years, it will also reinforce the need to become more sustainable within drug delivery research. In 2021, I was appointed professor for pharmaceutical biology at the Friedrich-Alexander-University Erlangen-Nürnberg. Our research is at the interface between developing biogenic therapies and understanding of bacterial infections. In this contribution to the Orations - New Horizons of the Journal of Controlled Release, I would like to underline the need for future sustainable approaches in our research area, by highlighting selected examples from the fields of infection research, natural product characterisation and extracellular vesicles. My aim is to put into perspective current issues for these research topics, but also encourage our current student-training framework to contribute to education for sustainable development. This contribution is a personal statement to increase the overall awareness for sustainability challenges in drug delivery and beyond.

Targeting bacterial biofilms using vancomycin and multivalent cell-penetrating peptide labeled quantum dots

Bacterial biofilms are highly resilient microbial musters that are difficult to eradicate, driving the development of novel therapeutic strategies. The current study aims to investigate the therapeutic efficacy of cell-penetrating peptide-based targeted delivery of vancomycin functionalized quantum dots in eradicating biofilm formation in gram-positive and gram-negative bacterial strains. The conjugate was characterized using fluorimetry, UV-visible spectroscopy, gel electrophoresis, and zeta potential. The conjugate was then tested for antimicrobial and antibiofilm activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, and it demonstrated excellent antimicrobial as well as antibiofilm activity against all the tested strains. The findings indicated that the conjugate was capable of overcoming bacterial resistance of bacteria in addition to the eradication of biofilms at effective concentrations.

Amikacin liposome and Mycobacterium avium complex: A systematic review

INTRODUCTION

The prevalence of Mycobacterium avium complex (MAC) is increasing globally. Macrolide-based multidrug regimens have been recommended as the first-line treatment for patients with MAC pulmonary disease. However, developing macrolide resistance was associated with poor treatment outcomes and increased mortality. In 2018, the U.S. Food and Drug Administration approved liposomal amikacin for inhalation (LAI) to treat refractory MAC pulmonary disease. The current systematic review aimed to evaluate LAI's outcomes and adverse events in MAC pulmonary disease.

METHODS

The systematic search was performed in PubMed/Medline, EMBASE, and the Cochrane Controlled Register of Trials (CENTRAL) up to March 8, 2022. The search terms included Mycobacterium avium complex, MAC, amikacin, and liposomal amikacin.

RESULTS

After reviewing 1284 records, four papers met the inclusion criteria, including three clinical trials and one prospective cohort study. These studies showed that adding LAI to guideline-based therapies can increase sputum culture conversion rate and achieve early sustained (negative sputum culture results for 12 months with treatment) and durable (negative sputum culture results for three months after treatment) negative sputum culture. In addition, extended LAI use was a potential benefit in patients considered refractory to initial treatment. The most prevalent treatment-emergent adverse events (TEAE) reported in the LAI group were the respiratory TEAE.

CONCLUSIONS

LAI could increase the sputum culture conversion rate and achieve early sustainable, durable negative sputum culture. However, additional large-scale research is required to confirm the results.

Perspective on the Application of Erythrocyte Liposome-Based Drug Delivery for Infectious Diseases

Nanoparticles are explored as drug carriers with the promise for the treatment of diseases to increase the efficacy and also reduce side effects sometimes seen with conventional drugs. To accomplish this goal, drugs are encapsulated in or conjugated to the nanocarriers and selectively delivered to their targets. Potential applications include immunization, the delivery of anti-cancer drugs to tumours, antibiotics to infections, targeting resistant bacteria, and delivery of therapeutic agents to the brain. Despite this great promise and potential, drug delivery systems have yet to be established, mainly due to their limitations in physical instability and rapid clearance by the host's immune response. Recent interest has been taken in using red blood cells (RBC) as drug carriers due to their naturally long circulation time, flexible structure, and direct access to many target sites. This includes coating of nanoparticles with the membrane of red blood cells, and the fabrication and manipulation of liposomes made of the red blood cells' cytoplasmic membrane. The properties of these erythrocyte liposomes, such as charge and elastic properties, can be tuned through the incorporation of synthetic lipids to optimize physical properties and the loading efficiency and retention of different drugs. Specificity can be established through the anchorage of antigens and antibodies in the liposomal membrane to achieve targeted delivery. Although still at an early stage, this erythrocyte-based platform shows first promising results in vitro and in animal studies. However, their full potential in terms of increased efficacy and side effect minimization still needs to be explored in vivo.

Tobramycin Nanoantibiotics and Their Advantages: A Minireview

Nowadays, antimicrobial resistance (AMR) represents a challenge for antibiotic therapy, mostly involving Gram-negative bacteria. Among the strategies activated to overcome AMR, the repurposing of already available antimicrobial molecules by encapsulating them in drug delivery systems, such as nanoparticles (NPs) and also engineered NPs, seems to be promising. Tobramycin is a powerful and effective aminoglycoside, approved for complicated infections and reinfections and indicated mainly against Gram-negative bacteria, such as Pseudomonas aeruginosa, Escherichia coli, Proteus, Klebsiella, Enterobacter, Serratia, Providencia, and Citrobacter species. However, the drug presents several side effects, mostly due to dose frequency, and for this reason, it is a good candidate for nanomedicine formulation. This review paper is focused on what has been conducted in the last 20 years for the development of Tobramycin nanosized delivery systems (nanoantibiotics), with critical discussion and comparison. Tobramycin was selected as the antimicrobial drug because it is a wide-spectrum antibiotic that is effective against both Gram-positive and Gram-negative aerobic bacteria, and it is characterized by a fast bactericidal effect, even against multidrug-resistant microorganisms (MDR).

The Efficacy of Colistin Combined with Amikacin or Levofloxacin against Pseudomonas aeruginosa Biofilm Infection

Pseudomonas aeruginosa (PA) biofilm infection is clinically prevalent and difficult to eradicate. In the present work, we aimed to evaluate the in vitro and in vivo efficacy of colistin (COL)-based combinations against PA biofilm. MICs and fractional inhibitory concentration indexes (FICIs) of four antibiotics (COL, amikacin, levofloxacin, and meropenem) to bioluminescent strain PAO1, carbapenem-resistant PAO1 (CRPAO1), and clinically isolated strains were assessed. Minimal biofilm eradication concentrations (MBECs) of monotherapy and combinations were examined by counting the live bacteria in biofilm, accompanied by visual confirmation using confocal laser-scanning microscopy. An animal biofilm infection model was established by implanting biofilm subcutaneously, and the therapeutic effect was evaluated according to the change in luminescence through a live animal bio-photonic imaging system. In vitro, even combined with 4 or 8 mg/L COL, meropenem needed to reach 128 or 256 mg/L to eradicate the biofilm. Moreover, 2 mg/L COL combined with 32 mg/L amikacin or 4-8 mg/L levofloxacin could kill the PAO1 and CRPAO1 in biofilm within 24 h. In vivo, COL combined with amikacin or levofloxacin could shorten the eradication time of biofilm than monotherapy. For PAO1 biofilm, combination therapy could eradicate the biofilm in all mice on the 5th day, whereas monotherapy only eradicated biofilms in almost half of the mice. For CRPAO1 biofilm, the biofilm eradication rate on the 6th day in the COL+ amikacin, amikacin, or COL alone regimen was 90%, 10%, or 40%, respectively. COL combined with levofloxacin did not show a better effect than each individual antibiotic. COL-based combinations containing levofloxacin or amikacin were promising choices for treating PA biofilm infection. IMPORTANCE Infections associated with PA biofilm formation are extremely challenging. When monotherapy fails to achieve optimal efficacy, combination therapy becomes the last option. After evaluating multiple drug combinations through a series of experiments in vitro and in vivo, we confirmed that colistin-based combinations containing levofloxacin or amikacin were promising choices for treating PA biofilm infection. The efficacy of these combinations derives from the different bactericidal mechanisms and the bacterial susceptibility to each antibiotic. This study provided a new regimen to solve the incurable problem of biofilm by using COL combined with other antibiotics.

Development of Ulvan-Containing Liposomes as Antibacterial Drug Delivery Platforms

Liposomes, due to their safety profile and targeting ability, are among the most studied nanocarriers as antimicrobial delivery systems. However, due to lack of stability and the non-specific interaction of liposomes with cells and proteins, their use is relatively limited. Aiming to overcome these drawbacks, it was envisaged that incorporation of ulvan, a bioactive marine sulfated polysaccharide isolated from green algae, in liposomes could improve their physicochemical properties and overall stability. Thus, we initially studied the interactions of ulvan with neutral, negatively, and positively charged lipids using Differential Scanning Calorimetry and subsequently, based on the obtained results, we prepared the respective ulvan–containing neutral and charged liposomes, where ulvan interacts with both lipid chains and polar groups in the liposomal bilayer. In a further step, we entrapped in the liposomes fusidic acid, used as a model antibacterial drug, and proceeded with the evaluation of their antibacterial activity against Staphylococcus aureus. The physicochemical properties (size and ζ-potential), stability, morphology, and entrapment efficiency of the prepared liposomal formulations were determined.

Medicinal Chemistry of Inhibitors Targeting Resistant Bacteria

The discovery of antibiotics was a revolutionary feat that provided countless health benefits. The identification of penicillin by Alexander Fleming initiated the era of antibiotics, represented by constant discoveries that enabled effective treatments for the different classes of diseases caused by bacteria. However, the indiscriminate use of these drugs allowed the emergence of resistance mechanisms of these microorganisms against the available drugs. In addition, the constant discoveries in the 20th century generated a shortage of new molecules, worrying health agencies and professionals about the appearance of multidrug-resistant strains against available drugs. In this context, the advances of recent years in molecular biology and microbiology have allowed new perspectives in drug design and development, using the findings related to the mechanisms of bacterial resistance to generate new drugs that are not affected by such mechanisms and supply new molecules to be used to treat resistant bacterial infections. Besides, a promising strategy against bacterial resistance is the combination of drugs through adjuvants, providing new expectations in designing new antibiotics and new antimicrobial therapies. Thus, this manuscript will address the main mechanisms of bacterial resistance under the understanding of medicinal chemistry, showing the main active compounds against efflux mechanisms, and also the application of the use of drug delivery systems, and finally, the main potential natural products as adjuvants or with promising activity against resistant strains.

Bacteriophage and Bacterial Susceptibility, Resistance, and Tolerance to Antibiotics

Bacteriophages, viruses that infect and replicate within bacteria, impact bacterial responses to antibiotics in complex ways. Recent studies using lytic bacteriophages to treat bacterial infections (phage therapy) demonstrate that phages can promote susceptibility to chemical antibiotics and that phage/antibiotic synergy is possible. However, both lytic and lysogenic bacteriophages can contribute to antimicrobial resistance. In particular, some phages mediate the horizontal transfer of antibiotic resistance genes between bacteria via transduction and other mechanisms. In addition, chronic infection filamentous phages can promote antimicrobial tolerance, the ability of bacteria to persist in the face of antibiotics. In particular, filamentous phages serve as structural elements in bacterial biofilms and prevent the penetration of antibiotics. Over time, these contributions to antibiotic tolerance favor the selection of resistance clones. Here, we review recent insights into bacteriophage contributions to antibiotic susceptibility, resistance, and tolerance. We discuss the mechanisms involved in these effects and address their impact on bacterial fitness.

Neutralization of ionic interactions by dextran-based single-chain nanoparticles improves tobramycin diffusion into a mature biofilm

The extracellular matrix protects biofilm cells by reducing diffusion of antimicrobials. Tobramycin is an antibiotic used extensively to treat P. aeruginosa biofilms, but it is sequestered in the biofilm periphery by the extracellular negative charge matrix and loses its efficacy significantly. Dispersal of the biofilm extracellular matrix with enzymes such as DNase I is another promising therapy that enhances antibiotic diffusion into the biofilm. Here, we combine the charge neutralization of tobramycin provided by dextran-based single-chain polymer nanoparticles (SCPNs) together with DNase I to break the biofilm matrix. Our study demonstrates that the SCPNs improve the activity of tobramycin and DNase I by neutralizing the ionic interactions that keep this antibiotic in the biofilm periphery. Moreover, the detailed effects and interactions of nanoformulations with extracellular matrix components were revealed through time-lapse imaging of the P. aeruginosa biofilms by laser scanning confocal microscopy with specific labeling of the different biofilm components.

Early-Phase Adverse Effects and Management of Liposomal Amikacin Inhalation for Refractory Mycobacterium avium Complex Lung Disease in Real-World Settings

Purpose

Amikacin liposome inhalation suspension (ALIS), which efficiently allows amikacin to reach the pulmonary periphery for effect while minimising systemic adverse effects, was recently approved for treating Mycobacterium avium complex (MAC) infections. The international Phase 3 open-label clinical trials showed promising results, contributing to sputum culture conversion, but few studies have examined the efficacy and adverse effects of ALIS using real-world data. We identified the clinical outcome and adverse effects of ALIS in the early phase of treatment, for more effective and safe use in clinical practice.

Patients and Methods

The study population consisted of patients with MAC lung disease (MAC-LD), introduced to ALIS therapy after July 2021 at Keio University Hospital due to poor response to multidrug therapy. The sputum smear/culture results, symptoms, adverse effects, and the serum amikacin concentrations of the early phase of ALIS inhalation therapy were examined.

Results

A total of 11 patients (9 women; median age 64.6 years) were included in this study. The median disease duration of MAC-LD was 13.7 years, and all patients exhibited a positive culture at the beginning of ALIS inhalation. Three of the six patients (50.0%) who were initially sputum-smear-positive were confirmed to have become sputum-smear-negative within one month, including one culture conversion. ALIS inhalation therapy caused some adverse effects in nine patients (81.8%); however, no serious systemic adverse effects were observed. The most common adverse effect was hoarseness (72.7%), which mostly occurred around 1 week after initiation. The medians of peak serum amikacin concentrations were 1.4 and 2.3 μg/mL for the first and third inhalations, respectively. Trough serum concentrations just before the third inhalation were <1.2 μg/mL in all patients.

Conclusion

ALIS therapy might be a treatment option for patients with refractory MAC infection with long disease duration and a poor response to guideline-based therapy.

Recent Advances in Antimicrobial Nano-Drug Delivery Systems

Infectious diseases are among the major health issues of the 21st century. The substantial use of antibiotics over the years has contributed to the dissemination of multidrug resistant bacteria. According to a recent report by the World Health Organization, antibacterial (ATB) drug resistance has been one of the biggest challenges, as well as the development of effective long-term ATBs. Since pathogens quickly adapt and evolve through several strategies, regular ATBs usually may result in temporary or noneffective treatments. Therefore, the demand for new therapies methods, such as nano-drug delivery systems (NDDS), has aroused huge interest due to its potentialities to improve the drug bioavailability and targeting efficiency, including liposomes, nanoemulsions, solid lipid nanoparticles, polymeric nanoparticles, metal nanoparticles, and others. Given the relevance of this subject, this review aims to summarize the progress of recent research in antibacterial therapeutic drugs supported by nanobiotechnological tools.

Recent Advances in Multifunctional Hydrogels for the Treatment of Osteomyelitis

Osteomyelitis (OM), a devastating disease caused by microbial infection of bones, remains a major challenge for orthopedic surgeons. Conventional approaches for prevention and treatment of OM are unsatisfactory. Various alternative strategies have been proposed, among which, hydrogel-based strategies have demonstrated potential due to their unique properties, including loadable, implantable, injectable, printable, degradable, and responsive to stimuli. Several protocols, including different hydrogel designs, selection of antimicrobial agent, co-administration of bone morphogenetic protein 2 (BMP 2), and nanoparticles, have been shown to improve the biological properties, including antimicrobial effects, osteo-induction, and controlled drug delivery. In this review, we describe the current and future directions for designing hydrogels and their applications to improve the biological response to OM in vivo.

Management of Mycobacterium avium complex and Mycobacterium abscessus pulmonary disease: therapeutic advances and emerging treatments

Nontuberculous mycobacterial pulmonary disease (NTM-PD) remains a challenging condition to diagnose and treat effectively. Treatment of NTM-PD is prolonged, frequently associated with adverse effects and has variable success. In this review, we consider the factors influencing clinicians when treating NTM-PD and discuss outcomes from key studies on the pharmacological management of Mycobacterium avium complex pulmonary disease and M. abscessus pulmonary disease. We highlight issues relating to treatment-related toxicity and provide an overview of repurposed and emerging therapies for NTM-PD.

Therapeutic Values of Earthworm Species Extract from Azad Kashmir as Anticoagulant, Antibacterial, and Antioxidant Agents

Aims

Current research aimed to explore the therapeutic values of different earthworms as antibacterial, anticoagulant, and antioxidant agents.

Methods

Ten different earthworms, i.e., Amynthas corticis, Amynthas gracilis, Pheretima posthuma, Eisenia fetida, Aporrectodea rosea, Allolobophora chlorotica, Aporrectodea trapezoides, Polypheretima elongata, Aporrectodea caliginosa, and Pheretima hawayana, were collected and screened for biological activities. Antibacterial effect analysis of earthworm species was done against fourteen bacterial pathogens, i.e., Escherichia coli, Serratia marcescens, Streptococcus pyogenes, Staphylococcus epidermidis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa (1), Salmonella typhimurium, Shigella flexneri, Enterobacter amnigenus, Serratia odorifera, Pseudomonas aeruginosa (2), Staphylococcus warneri, and Lactobacillus curvatus, via agar well diffusion, crystal violet, MTT, agar disc diffusion, and direct bioautography assays. Antioxidant potential was evaluated through ABTS and DPPH assays. Lipolytic, proteolytic, and amylolytic assays were done for lipase, protease, and amylase enzymes confirmation. In vitro anticoagulant effects were examined in the blood samples by measuring prothrombin time.

Results

Results revealed that all earthworm extracts showed the inhibition of all tested bacterial pathogens except P. aeruginosa (1), P. aeruginosa (2), S. warneri, and L. curvatus. The maximum zone of inhibition of E. coli was recorded as 14.66 ± 0.57 mm by A. corticis, 25.0 ± 0.0 mm by P. posthuma, 20.0 ± 0.0 mm by E. fetida, and 20.0 ± 0.0 mm by A. trapezoid. Cell proliferation, biofilm inhibition, the synergistic effect of extracts along with antibiotics, and direct bioautography supported the results of agar well diffusion assay. Similarly, P. hawayana, A. corticis, A. caliginosa, and A. trapezoids increase the prothrombin time more efficiently compared to other earthworms. A. corticis, A. gracilis, A. rosea, A. chlorotica, P. elongata, and A. trapezoides showed maximum DPPH scavenging potential effect.

Conclusions

The coelomic fluid of earthworms possessed several bioactive compounds/enzymes/antioxidants that play an important role in the bacterial inhibition and act as anticoagulant agents. Therefore, the development of new therapeutic drugs from invertebrates could be effective and potential for the prevention of the emergence of multidrug-resistant bacteria.

Strategies to Overcome Biological Barriers Associated with Pulmonary Drug Delivery

While the inhalation route has been used for millennia for pharmacologic effect, the biological barriers to treating lung disease created real challenges for the pharmaceutical industry until sophisticated device and formulation technologies emerged over the past fifty years. There are now several inhaled device technologies that enable delivery of therapeutics at high efficiency to the lung and avoid excessive deposition in the oropharyngeal region. Chemistry and formulation technologies have also emerged to prolong retention of drug at the active site by overcoming degradation and clearance mechanisms, or by reducing the rate of systemic absorption. These technologies have also been utilized to improve tolerability or to facilitate uptake within cells when there are intracellular targets. This paper describes the biological barriers and provides recent examples utilizing formulation technologies or drug chemistry modifications to overcome those barriers.

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.

Membrane Organization Strategies in Vesicular Antibiotic Delivery

Small molecule antibiotics are often derived from microorganisms that thrive in competitive environments. Their importance as therapeutics for infectious disease in humans has been established over many years. It has now become clear that antibiotic-producing organisms use packaging and delivery in the form of vesicles in many cases. A similar strategy has evolved in recent decades in the pharmaceutical industry for formulation of antibiotic therapies. The top-down approach that has evolved over millions of years in various micro-organisms has generated complex, efficient delivery systems that we are just now beginning to understand. The bottom-up formulation approach involves simple, safe compositions, which are being continually enhanced by trying to add features of which the natural systems inform us. A comparison is made here of these paradigms. Despite the differences, there are a number of common features in the basic physical and biological requirements that must be satisfied. In this review, illustration and comparison of some of these requirements is given, demonstrating the ongoing challenges in this area of research.

Inhaled Medicines: Past, Present, and Future

The purpose of this review is to summarize essential pharmacological, pharmaceutical, and clinical aspects in the field of orally inhaled therapies that may help scientists seeking to develop new products. After general comments on the rationale for inhaled therapies for respiratory disease, the focus is on products approved approximately over the last half a century. The organization of these sections reflects the key pharmacological categories. Products for asthma and chronic obstructive pulmonary disease include β -2 receptor agonists, muscarinic acetylcholine receptor antagonists, glucocorticosteroids, and cromones as well as their combinations. The antiviral and antibacterial inhaled products to treat respiratory tract infections are then presented. Two "mucoactive" products-dornase α and mannitol, which are both approved for patients with cystic fibrosis-are reviewed. These are followed by sections on inhaled prostacyclins for pulmonary arterial hypertension and the challenging field of aerosol surfactant inhalation delivery, especially for prematurely born infants on ventilation support. The approved products for systemic delivery via the lungs for diseases of the central nervous system and insulin for diabetes are also discussed. New technologies for drug delivery by inhalation are analyzed, with the emphasis on those that would likely yield significant improvements over the technologies in current use or would expand the range of drugs and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of approved orally inhaled drug products for a variety of respiratory diseases and for systemic administration should be helpful in making judicious decisions about the development of new or improved inhaled drugs. These aspects include the choices of the active ingredients, formulations, delivery systems suitable for the target patient populations, and, to some extent, meaningful safety and efficacy endpoints in clinical trials.

Inflammation-modulating nanoparticles for pneumonia therapy

Pneumonia is a common but serious infectious disease, and is the sixth leading cause for death. The foreign pathogens such as viruses, fungi, and bacteria establish an inflammation response after interaction with lung, leading to the filling of bronchioles and alveoli with fluids. Although the pharmacotherapies have shown their great effectiveness to combat pathogens, advanced methods are under developing to treat complicated cases such as virus-infection and lung inflammation or acute lung injury (ALI). The inflammation modulation nanoparticles (NPs) can effectively suppress immune cells and inhibit inflammatory molecules in the lung site, and thereby alleviate pneumonia and ALI. In this review, the pathological inflammatory microenvironments in pneumonia, which are instructive for the design of biomaterials therapy, are summarized. The focus is then paid to the inflammation-modulating NPs that modulate the inflammatory cells, cytokines and chemokines, and microenvironments of pneumonia for better therapeutic effects. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease.

Nanotechnology Based Approaches in Phage Therapy: Overcoming the Pharmacological Barriers

With the emergence and spread of global antibiotic resistance and the need for searching safer alternatives, there has been resurgence in exploring the use of bacteriophages in the treatment of bacterial infections referred as phage therapy. Although modern phage therapy has come a long way as demonstrated by numerous efficacy studies but the fact remains that till date, phage therapy has not received regulatory approval for human use (except for compassionate use).Thus, to hit the clinical market, the roadblocks need to be seriously addressed and gaps mended with modern solution based technologies. Nanotechnology represents one such ideal and powerful tool for overcoming the pharmacological barriers (low stability, poor in-vivo retention, targeted delivery, neutralisation by immune system etc.) of administered phage preparations.In literature, there are many review articles on nanotechnology and bacteriophages but these are primarily focussed on highlighting the use of lytic and temperate phages in different fields of nano-medicine such as nanoprobes, nanosensors, cancer diagnostics, cancer cell targeting, drug delivery through phage receptors, phage display etc. Reviews specifically focused on the use of nanotechnology driven techniques strictly to improve phage therapy are however limited. Moreover, these review if present have primarily focussed on discussing encapsulation as a primary method for improving the stability and retention of phage(s) in the body.With new advances made in the field of nanotechnology, approaches extend from mere encapsulation to recently adopted newer strategies. The present review gives a detailed insight into the more recent strategies which include 1) use of lipid based nano-carriers (liposomes, transfersomes etc.) 2) adopting microfluidic based approach, surface modification methods to further enhance the efficiency and stability of phage loaded liposomes 3) Nano- emulsification approach with integration of microfluidics for producing multiple emulsions (suitable for phage cocktails) with unique control over size, shape and drop morphology 4) Phage loaded nanofibers produced by electro-spinning and advanced core shell nanofibers for immediate, biphasic and delayed release systems and 5) Smart release drug delivery platforms that allow superior control over dosing and phage release as and when required. All these new advances are aimed at creating a suitable housing system for therapeutic bacteriophage preparations while targeting the multiple issues of phage therapy i.e., improving phage stability and titers, improving in-vivo retention times, acting as suitable delivery systems for sustained release at target site of infection, improved penetration into biofilms and protection from immune cell attack. The present review thus aims at giving a complete insight into the recent advances (2010 onwards) related to various nanotechnology based approaches to address the issues pertaining to phage therapy. This is essential for improving the overall therapeutic index and success of phage therapy for future clinical approval.

Nano- and Macroscale Imaging of Cholesterol Linoleate and Human Beta Defensin 2-Induced Changes in Pseudomonas aeruginosa Biofilms

The biofilm production of Pseudomonas aeruginosa (PA) is central to establishing chronic infection in the airways in cystic fibrosis. Epithelial cells secrete an array of innate immune factors, including antimicrobial proteins and lipids, such as human beta defensin 2 (HBD2) and cholesteryl lineolate (CL), respectively, to combat colonization by pathogens. We have recently shown that HBD2 inhibits biofilm production by PA, possibly linked to interference with the transport of biofilm precursors. Considering that both HBD2 and CL are increased in airway fluids during infection, we hypothesized that CL synergizes with HBD2 in biofilm inhibition. CL was formulated in phospholipid-based liposomes (CL-PL). As measured by atomic force microscopy of single bacteria, CL-PL alone and in combination with HBD2 significantly increased bacterial surface roughness. Additionally, extracellular structures emanated from untreated bacterial cells, but not from cells treated with CL-PL and HBD2 alone and in combination. Crystal violet staining of the biofilm revealed that CL-PL combined with HBD2 effected a significant decrease of biofilm mass and increased the number of larger biofilm particles consistent with altered cohesion of formed biofilms. These data suggest that CL and HBD2 affect PA biofilm formation at the single cell and community-wide level and that the community-wide effects of CL are enhanced by HBD2. This research may inform future novel treatments for recalcitrant infections in the airways of CF patients.

Development of pH-responsive nanocomposites with remarkably synergistic antibiofilm activities based on ultrasmall silver nanoparticles in combination with aminoglycoside antibiotics

Bacterial biofilms are responsible for many chronic infections because antibacterial agents exhibit poor penetration into the dense matrix barrier and cannot easily reach the internal bacteria. Herein, we reported pH-responsive nanocomposites (PDA@Kana-AgNPs) that could penetrate and disperse biofilms, which were synthesized by the combination of ultrasmall silver nanoparticles (AgNPs) and kanamycin, and then coating with polydopamine. Confocal fluorescence imaging indicated that PDA@Kana-AgNPs could respond to the acidic microenvironment of biofilms, leading to biofilm-triggered on- demand drug release in situ. The zone of inhibition test and Resazurin assay showed that the combination of kanamycin and AgNPs had greater antimicrobial activity against test strains (Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Escherichia coli BL21) than when applied separately. The crystal violet staining test demonstrated that biofilms were effectively dispersed by the proposed nanocomposites. Biocompatibility was also evaluated, which showed that PDA@Kana-AgNPs were non-toxic to mammalian cells. Therefore, the proposed pH-responsive nanocomposites held great potential for efficient antibiotics delivery and showed synergistic antibacterial and antibiofilm activities. This strategy could also be used to encapsulate a variety of antibiotics in combination with other drugs or materials, thereby showing therapeutic potential in preventing biofilm-related infections and realizing fluorescence imaging in situ.

Breaking the barriers for the delivery of amikacin: Challenges, strategies, and opportunities

Hypodermic delivery of amikacin is a widely adopted treatment modality for severe infections, including bacterial septicemia, meningitis, intra-abdominal infections, burns, postoperative complications, and urinary tract infections in both paediatric and adult populations. In most instances, the course of treatment requires repeated bolus doses of amikacin, prolonged hospitalization, and the presence of a skilled healthcare worker for administration and continuous therapeutic monitoring to manage the severe adverse effects. Amikacin is hydrophilic and exhibits a short half-life, which further challenges the delivery of sufficient systemic concentrations when administered by the oral or transdermal route. In this purview, the exploitation of novel controlled and sustained release drug delivery platforms is warranted. Furthermore, it has been shown that novel delivery systems are capable of increasing the antibacterial activity of amikacin at lower doses when compared to the conventional formulations and also aid in overcoming the development of drug-resistance, which currently is a significant threat to the healthcare system worldwide. The current review presents a comprehensive overview of the developmental history of amikacin, the mechanism of action in virulent strains as well as the occurrence of resistance, and various emerging drug delivery solutions developed both by the academia and the industry. The examples outlined within the review provides significant pieces of evidence on novel amikacin formulations in the field of antimicrobial research paving the path for future therapeutic interventions that will result in improved clinical outcome.

Liposomal drug delivery to manage nontuberculous mycobacterial pulmonary disease and other chronic lung infections

Nontuberculous mycobacterial (NTM) pulmonary disease is a chronic respiratory infection associated with declining lung function, radiological deterioration and significantly increased morbidity and mortality. Patients often have underlying lung conditions, particularly bronchiectasis and COPD. NTM pulmonary disease is difficult to treat because mycobacteria can evade host defences and antimicrobial therapy through extracellular persistence in biofilms and sequestration into macrophages. Management of NTM pulmonary disease remains challenging and outcomes are often poor, partly due to limited penetration of antibiotics into intracellular spaces and biofilms. Efficient drug delivery to the site of infection is therefore a key objective of treatment, but there is high variability in lung penetration by antibiotics. Inhalation is the most direct route of delivery and has demonstrated increased efficacy of antibiotics like amikacin compared with systemic administration. Liposomes are small, artificial, enclosed spherical vesicles, in which drug molecules can be encapsulated to provide controlled release, with potentially improved pharmacokinetics and reduced toxicity. They are especially useful for drugs where penetration of cell membranes is essential. Inhaled delivery of liposomal drug solutions can therefore facilitate direct access to macrophages in the lung where the infecting NTM may reside. A range of liposomal drugs are currently being evaluated in respiratory diseases.

Liposome-encapsulated antibiotics can optimise respiratory disease treatment. Amikacin liposomal inhalation suspension is effective in nontuberculous mycobacterial pulmonary disease that has failed to convert following oral guideline-based therapy.https://bit.ly/3f3ixIu

Filamentous Bacteriophages and the Competitive Interaction between Pseudomonas aeruginosa Strains under Antibiotic Treatment: a Modeling Study

Pseudomonas aeruginosa (Pa) is a major bacterial pathogen responsible for chronic lung infections in cystic fibrosis patients. Recent work has implicated Pf bacteriophages, nonlytic filamentous viruses produced by Pa, in the chronicity and severity of Pa infections. Pf phages act as structural elements in Pa biofilms and sequester aerosolized antibiotics, thereby contributing to antibiotic tolerance. Consistent with a selective advantage in this setting, the prevalence of Pf-positive (Pf+) bacteria increases over time in these patients. However, the production of Pf phages comes at a metabolic cost to bacteria, such that Pf+ strains grow more slowly than Pf-negative (Pf-) strains in vitro. Here, we use a mathematical model to investigate how these competing pressures might influence the relative abundance of Pf+ versus Pf- strains in different settings. Our model suggests that Pf+ strains of Pa cannot outcompete Pf- strains if the benefits of phage production falls onto both Pf+ and Pf- strains for a majority of parameter combinations. Further, phage production leads to a net positive gain in fitness only at antibiotic concentrations slightly above the MIC (i.e., concentrations for which the benefits of antibiotic sequestration outweigh the metabolic cost of phage production) but which are not lethal for Pf+ strains. As a result, our model suggests that frequent administration of intermediate doses of antibiotics with low decay rates and high killing rates favors Pf+ over Pf- strains. These models inform our understanding of the ecology of Pf phages and suggest potential treatment strategies for Pf+ Pa infections. IMPORTANCE Filamentous phages are a frontier in bacterial pathogenesis, but the impact of these phages on bacterial fitness is unclear. In particular, Pf phages produced by Pa promote antibiotic tolerance but are metabolically expensive to produce, suggesting that competing pressures may influence the prevalence of Pf+ versus Pf- strains of Pa in different settings. Our results identify conditions likely to favor Pf+ strains and thus antibiotic tolerance. This study contributes to a better understanding of the unique ecology of filamentous phages in both environmental and clinical settings and may facilitate improved treatment strategies for combating antibiotic tolerance.

Evaluation of Pseudomonas aeruginosa pathogenesis and therapeutics in military-relevant animal infection models

Modern combat-related injuries are often associated with acute polytrauma. As a consequence of severe combat-related injuries, a dysregulated immune response results in serious infectious complications. The gram-negative bacterium Pseudomonas aeruginosa is an opportunistic pathogen that often causes life-threatening bloodstream, lung, bone, urinary tract, and wound infections following combat-related injuries. The rise in the number of multidrug-resistant P. aeruginosa strains has elevated its importance to civilian clinicians and military medicine. Development of novel therapeutics and treatment options for P. aeruginosa infections is urgently needed. During the process of drug discovery and therapeutic testing, in vivo testing in animal models is a critical step in the bench-to-bedside approach, and required for Food and Drug Administration approval. Here, we review current and past literature with a focus on combat injury-relevant animal models often used to understand infection development, the interplay between P. aeruginosa and the host, and evaluation of novel treatments. Specifically, this review focuses on the following animal infection models: wound, burn, bone, lung, urinary tract, foreign body, and sepsis.

Long-term amikacin liposome inhalation suspension in cystic fibrosis patients with chronic P. aeruginosa infection

BACKGROUND

. In CLEAR-108-a phase 3, randomised, open-label study-once-daily amikacin liposome inhalation suspension (ALIS) was noninferior to twice-daily tobramycin inhalation solution (TIS) in improving lung function in patients with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa infection after 3 treatment cycles (28 days on/28 days off). The CLEAR-110 extension study (ClinicalTrials.gov: NCT01316276; EudraCT: 2011-000443-24) assessed long-term safety, tolerability, and efficacy of ALIS in eligible patients who completed CLEAR-108.

METHODS

. Patients received once-daily ALIS 590 mg for 12 treatment cycles (96 weeks). Patients were grouped by prior treatment: the "prior-ALIS" cohort received ALIS in CLEAR-108, and the "ALIS-naive" cohort received TIS in CLEAR-108.

RESULTS

. Overall, 206 patients (prior-ALIS, n=92; ALIS-naive, n=114) entered CLEAR-110 and received ≥1 dose of ALIS. Most patients (88.8%) experienced ≥1 treatment-emergent adverse event (TEAE) through day 672 (end of year 2). Most TEAEs (72.3%) were mild or moderate in severity. Severe TEAEs were reported in 31 patients (15.0%). Two life-threatening TEAEs (haemoptysis; intestinal obstruction) and 1 death (cardiac failure) were reported. Twenty-one patients (10.2%) discontinued treatment due to a TEAE (mostly infective pulmonary exacerbation of CF). Mean change from baseline in forced expiratory volume in 1 second percent predicted at day 672 was -3.1% (prior-ALIS, -4.0%; ALIS-naive, -2.3%). Mean change from baseline in sputum density of P. aeruginosa at day 672 was 0.02 (prior-ALIS, -0.16; ALIS-naive, 0.19) log CFU/g.

CONCLUSIONS

. Long-term treatment with ALIS was well tolerated with a favourable adverse event profile and demonstrated continued antibacterial activity in CF patients with chronic P. aeruginosa infection.