Thioridazine in PLGA nanoparticles reduces toxicity and improves rifampicin therapy against mycobacterial infection in zebrafish

Synthesis and Structure of Novel Phenothiazine Derivatives, and Compound Prioritization via In Silico Target Search and Screening for Cytotoxic and Cholinesterase Modulatory Activities in Liver Cancer Cells and In Vivo in Zebrafish

Phenothiazines (PTZ) are antipsychotics known to modulate a variety of neurotransmitter activities that include dopaminergic and cholinergic signaling and have been identified as potential anticancer agents in vitro. However, it is important to also test whether a highly cytotoxic, repurposed, or novel PTZ has low toxicity and neuromodulatory activity in vivo using vertebrate model organisms, such as zebrafish. In this study, we synthesized novel phenothiazines and screened them in vitro in liver cancer and in vivo in zebrafish embryos/larvae. The syntheses of several intermediate PTZ 10-yl acyl chlorides were followed by elemental analysis and determination of 1H NMR and 13C NMR mass (ESI+) spectra of a large number of novel PTZ 10-carboxamides. Cytotoxicities of 28 PTZ derivatives (1-28) screened against Hep3B and SkHep1 liver cancer cell lines revealed five intermediate and five novel leads along with trifluoperazine (TFP), prochlorperazine (PCP), and perphenazine, which are relatively more cytotoxic than the basic PTZ core. Overall, the derivatives were more cytotoxic to Hep3B than SkHep1 cells. Moreover, in silico target screening identified cholinesterases as some of the commonest targets of the screened phenothiazines. Interestingly, molecular docking studies with acetylcholinesterase (AChE) and butyrylcholinesterase proteins showed that the most cytotoxic compounds 1, 3, PCP, and TFP behaved similar to Huprin W in their amino acid interactions with the AChE protein. The highly cytotoxic intermediate PTZ derivative 1 exhibited a relatively lower toxicity profile than those of 2 and 3 during the zebrafish development. It also modulated in vivo the cholinesterase activity in a dose-dependent manner while significantly increasing the total cholinesterase activity and/or ACHE mRNA levels, independent of the liver cancer cell type. Our screen also identified novel phenothiazines, i.e., 8 and 10, with significant cytotoxic and cholinesterase modulatory effects in liver cancer cells; yet both compounds had low levels of toxicity in zebrafish. Moreover, they modulated the cholinesterase activity or expression of ACHE in a cancer cell line-specific manner, and compound 10 significantly inhibited the cholinesterase activity in zebrafish. Accordingly, using a successful combination of in silico, in vitro, and in vivo approaches, we identified several lead anticancer and cholinesterase modulatory PTZ derivatives for future research.

A quality-by-design strategic approach for the development of bedaquiline-pretomanid nanoparticles as inhalable dry powders for TB treatment

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (M.tb) and is the second leading cause of death from an infectious disease globally. The disease mainly affects the lungs and forms granulomatous lesions that encapsulate the bacteria, making treating TB challenging. The current treatment includes oral administration of bedaquiline (BDQ) and pretomanid (PTD); however, patients suffer from severe systemic toxicities, low lung drug concentration, and non-adherence. In this study, we developed BDQ-PTD loaded nanoparticles as inhalable dry powders for pulmonary TB treatment using a Quality-by-Design (QbD) approach. The BDQ-PTD combination showed an additive/synergistic effect for M.tb inhibition in vitro, and the optimized drug ratio (1:4) was successfully loaded into polymeric nanoparticles (PLGA NPs). The QbD approach was implemented by identifying the quality target product profile (QTPPs), critical quality attributes (CQAs), and critical process parameters (CPPs) to develop efficient design space for dry powder preparation using spray drying. The three-factorial and three-level Box-Behnken Design was used to assess the effect of process parameters (CPPs) on product quality (CQAs). The Design of Experiments (DoE) analysis showed different regression models for product quality responses and helped optimize process parameters to meet QTPPs. The optimized dry powder showed excellent yield (72 ± 2 % w/w), high drug (BDQ-PTD) loading, low moisture content (<1% w/w), and spherical morphology. Further, aerosolization performance revealed the suitability of powder for deposition in the respiratory airways of the lungs (MMAD 2.4 µm and FPF > 75 %). In conclusion, the QbD approach helped optimize process parameters and develop dry powder with a suitable quality profile for inhalation delivery in TB patients.

Enhancing Therapeutic Efficacy against Brucella canis Infection in a Murine Model Using Rifampicin-Loaded PLGA Nanoparticles

The in vivo efficacy of rifampicin encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles was evaluated for the treatment of BALB/c mice experimentally infected with Brucella canis. The PLGA nanoparticles loaded with rifampicin (RNP) were prepared using the single emulsification-solvent evaporation technique, resulting in nanoparticles with a hydrodynamic diameter of 138 ± 6 nm. The zeta potential and polydispersity index values indicated that the system was relatively stable with a narrow size distribution. The release of rifampicin from the nanoparticles was studied in phosphate buffer at pH 7.4 and 37 °C. The release profile showed an initial burst phase, followed by a slower release stage attributed to nanoparticle degradation and relaxation, which continued for approximately 30 days until complete drug release. A combined model of rifampicin release, accounting for both the initial burst and the degradation-relaxation of the nanoparticles, effectively described the experimental data. The efficacy of RNP was studied in vivo; infected mice were treated with free rifampicin at concentrations of 2 mg per kilogram of mice per day (C1) and 4 mg per kilogram of mice per day (C2), as well as equivalent doses of RNP. Administration of four doses of the nanoparticles significantly reduced the B. canis load in the spleen of infected BALB/c mice. RNP demonstrated superior effectiveness compared to the free drug in the spleen, achieving reductions of 85.4 and 49.4%, respectively, when using C1 and 93.3 and 61.8%, respectively, when using C2. These results highlight the improved efficacy of the antibiotic when delivered through nanoparticles in experimentally infected mice. Therefore, the RNP holds promise as a potential alternative for the treatment of B. canis.

Π-Π interactions stabilize PeptoMicelle-based formulations of Pretomanid derivatives leading to promising therapy against tuberculosis in zebrafish and mouse models

Tuberculosis is the deadliest bacterial disease globally, threatening the lives of millions every year. New antibiotic therapies that can shorten the duration of treatment, improve cure rates, and impede the development of drug resistance are desperately needed. Here, we used polymeric micelles to encapsulate four second-generation derivatives of the antitubercular drug pretomanid that had previously displayed much better in vivo activity against Mycobacterium tuberculosis than pretomanid itself. Because these compounds were relatively hydrophobic and had limited bioavailability, we expected that their micellar formulations would overcome these limitations, reduce toxicities, and improve therapeutic outcomes. The polymeric micelles were based on polypept(o)ides (PeptoMicelles) and were stabilized in their hydrophobic core by π-π interactions, allowing the efficient encapsulation of aromatic pretomanid derivatives. The stability of these π-π-stabilized PeptoMicelles was demonstrated in water, blood plasma, and lung surfactant by fluorescence cross-correlation spectroscopy and was further supported by prolonged circulation times of several days in the vasculature of zebrafish larvae. The most efficacious PeptoMicelle formulation tested in the zebrafish larvae infection model almost completely eradicated the bacteria at non-toxic doses. This lead formulation was further assessed against Mycobacterium tuberculosis in the susceptible C3HeB/FeJ mouse model, which develops human-like necrotic granulomas. Following intravenous administration, the drug-loaded PeptoMicelles significantly reduced bacterial burden and inflammatory responses in the lungs and spleens of infected mice.

Asiaticoside polymeric nanoparticles for effective diabetic wound healing through increased collagen biosynthesis: In-vitro and in-vivo evaluation

Asiaticoside (AST) is a naturally available phytoconstituent that enables effective wound healing mainly by promoting collagen biosynthesis. However, the physicochemical nature of AST such as high molecular weight (959.12 g/mol), poor water solubility and poor permeability limits its therapeutic effects. This study aims to develop Asiaticoside polymeric nanoparticles (AST PNP) embedded in a gelatin based biodegradable hydrogel (15 % w/v) for application in the wound cavity to enable sustained release of AST and enhance its therapeutic effects. The AST PNP were fabricated in the desired size range (168.4 nm; PDI (0.09)) and the morphology, rate of fluid uptake, rate of water loss, and water vapor transmission rate of AST PNP incorporated hydrogel were determined. AST PNP gel showed porous structural morphology and possessed ideal characteristics as a graft for wound healing. The drug release kinetics and cellular uptake of AST PNP were investigated wherein, AST PNP demonstrated sustained release profile upto 24 h in comparison to free AST (complete release within 6 h) and exhibited an enhanced intra-cellular uptake in fibroblasts within 3 h compared to the free drug. In-vitrocell culture studies also demonstrated significant proliferation and migration of fibroblasts in the presence of AST PNP. Additionally, AST PNP gel upon application to the wounds of diabetic rats depicted improved wound healing efficacy in terms of improved collagen biosynthesis, upregulated COL-1 protein level (∼1.85 fold vs free AST), and enhanced expression of α-SMA compared to control groups. Altogether, formulation of AST as polymeric nanoparticles in a gel based carrier offered significant improvement in the therapeutic properties of AST for the management of diabetic wounds.

Nanoparticle entry into cells; the cell biology weak link

Nanoparticles (NP) are attractive options for the therapeutic delivery of active pharmaceutical drugs, proteins and nucleic acids into cells, tissues and organs. Research into the development and application of NP most often starts with a diverse group of scientists, including chemists, bioengineers and material and pharmaceutical scientists, who design, fabricate and characterize NP in vitro (Stage 1). The next step (Stage 2) generally investigates cell toxicity as well as the processes by which NP bind, are internalized and deliver their cargo to appropriate model tissue culture cells. Subsequently, in Stage 3, selected NP are tested in animal systems, mostly mouse. Whereas the chemistry-based development and analysis in Stage 1 is increasingly sophisticated, the investigations in Stage 2 are not what could be regarded as 'state-of-the-art' for the cell biology field and the quality of research into NP interactions with cells is often sub-standard. In this review we describe our current understanding of the mechanisms by which particles gain entry into mammalian cells via endocytosis. We summarize the most important areas for concern, highlight some of the most common mis-conceptions, and identify areas where NP scientists could engage with trained cell biologists. Our survey of the different mechanisms of uptake into cells makes us suspect that claims for roles for caveolae, as well as macropinocytosis, in NP uptake into cells have been exaggerated, whereas phagocytosis has been under-appreciated.

Recent advances in PLGA micro/nanoparticle delivery systems as novel therapeutic approach for drug-resistant tuberculosis

Tuberculosis is a severe infectious disease caused by Mycobacterium tuberculosis and is a significant public health concern globally. The World Health Organization (WHO) recommends a combination regimen of several drugs, such as rifampicin (RIF), isoniazid (INH), pyrazinamide (PZA), and ethambutol (ETB), to treat tuberculosis. However, these drugs have low plasma concentrations after oral administration and require multiple high doses, which may lead to the occurrence and development of drug-resistant tuberculosis. Micro/Nanotechnology drug delivery systems have considerable potential in treating drug-resistant tuberculosis, allowing the sustained release of the drug and delivery of the drug to a specific target. These system properties could improve drug bioavailability, reduce the dose and frequency of administration, and solve the problem of non-adherence to the prescribed therapy. This study systematically reviewed the recent advances in PLGA micro/nanoparticle delivery systems as a novel therapeutic approach for drug-resistant tuberculosis.

Antibiotic-Loaded Amphiphilic Chitosan Nanoparticles Target Macrophages and Kill an Intracellular Pathogen

In this work, levofloxacin (LVX), a third-generation fluoroquinolone antibiotic, is encapsulated within amphiphilic polymeric nanoparticles of a chitosan-g-poly(methyl methacrylate) produced by self-assembly and physically stabilized by ionotropic crosslinking with sodium tripolyphosphate. Non-crosslinked nanoparticles display a size of 29 nm and a zeta-potential of +36 mV, while the crosslinked counterparts display 45 nm and +24 mV, respectively. The cell compatibility, uptake, and intracellular trafficking are characterized in the murine alveolar macrophage cell line MH-S and the human bronchial epithelial cell line BEAS-2B in vitro. Internalization events are detected after 10 min and the uptake is inhibited by several endocytosis inhibitors, indicating the involvement of complex endocytic pathways. In addition, the nanoparticles are detected in the lysosomal compartment. Then, the antibacterial efficacy of LVX-loaded nanoformulations (50% w/w drug content) is assessed in MH-S and BEAS-2B cells infected with Staphylococcus aureus and the bacterial burden is decreased by 49% and 46%, respectively. In contrast, free LVX leads to a decrease of 8% and 5%, respectively, in the same infected cell lines. Finally, intravenous injection to a zebrafish larval model shows that the nanoparticles accumulate in macrophages and endothelium and demonstrate the promise of these amphiphilic nanoparticles to target intracellular infections.

Recent Developments in Drug Delivery for Treatment of Tuberculosis by Targeting Macrophages

Tuberculosis (TB) is among the greatest public health and safety concerns in the 21st century, Mycobacterium tuberculosis, which causes TB, infects alveolar macrophages and uses these cells as one of its primary sites of replication. The current TB treatment regimen, which consist of chemotherapy involving a combination of 3-4 antimicrobials for a duration of 6-12 months, is marked with significant side effects, toxicity, and poor compliance. Targeted drug delivery offers a strategy that could overcome many of the problems of current TB treatment by specifically targeting infected macrophages. Recent advances in nanotechnology and material science have opened an avenue to explore drug carriers that actively and passively target macrophages. This approach can increase the drug penetration into macrophages by using ligands on the nanocarrier that interact with specific receptors for macrophages. This review encompasses the recent development of drug carriers specifically targeting macrophages actively and passively. Future directions and challenges associated with development of effective TB treatment is also discussed.

Three-dimensional (3D) liver cell models - a tool for bridging the gap between animal studies and clinical trials when screening liver accumulation and toxicity of nanobiomaterials

Despite the exciting properties and wide-reaching applications of nanobiomaterials (NBMs) in human health and medicine, their translation from bench to bedside is slow, with a predominant issue being liver accumulation and toxicity following systemic administration. In vitro 2D cell-based assays and in vivo testing are the most popular and widely used methods for assessing liver toxicity at pre-clinical stages; however, these fall short in predicting toxicity for NBMs. Focusing on in vitro and in vivo assessment, the accurate prediction of human-specific hepatotoxicity is still a significant challenge to researchers. This review describes the relationship between NBMs and the liver, and the methods for assessing toxicity, focusing on the limitations they bring in the assessment of NBM hepatotoxicity as one of the reasons defining the poor translation for NBMs. We will then present some of the most recent advances towards the development of more biologically relevant in vitro liver methods based on tissue-mimetic 3D cell models and how these could facilitate the translation of NBMs going forward. Finally, we also discuss the low public acceptance and limited uptake of tissue-mimetic 3D models in pre-clinical assessment, despite the demonstrated technical and ethical advantages associated with them.

In vivo Evaluation of Non-viral NICD Plasmid-Loaded PLGA Nanoparticles in Developing Zebrafish to Improve Cardiac Functions

In the era of the advanced nanomaterials, use of nanoparticles has been highlighted in biomedical research. However, the demonstration of DNA plasmid delivery with nanoparticles for in vivo gene delivery experiments must be carefully tested due to many possible issues, including toxicity. The purpose of the current study was to deliver a Notch Intracellular Domain (NICD)-encoded plasmid via poly(lactic-co-glycolic acid) (PLGA) nanoparticles and to investigate the toxic environmental side effects for an in vivo experiment. In addition, we demonstrated the target delivery to the endothelium, including the endocardial layer, which is challenging to manipulate gene expression for cardiac functions due to the beating heart and rapid blood pumping. For this study, we used a zebrafish animal model and exposed it to nanoparticles at varying concentrations to observe for specific malformations over time for toxic effects of PLGA nanoparticles as a delivery vehicle. Our nanoparticles caused significantly less malformations than the positive control, ZnO nanoparticles. Additionally, the NICD plasmid was successfully delivered by PLGA nanoparticles and significantly increased Notch signaling related genes. Furthermore, our image based deep-learning analysis approach evaluated that the antibody conjugated nanoparticles were successfully bound to the endocardium to overexpress Notch related genes and improve cardiac function such as ejection fraction, fractional shortening, and cardiac output. This research demonstrates that PLGA nanoparticle-mediated target delivery to upregulate Notch related genes which can be a potential therapeutic approach with minimum toxic effects.

The zebrafish embryo as an in vivo model for screening nanoparticle-formulated lipophilic anti-tuberculosis compounds

With the increasing emergence of drug-resistant Mycobacterium tuberculosis strains, new and effective antibiotics against tuberculosis (TB) are urgently needed. However, the high frequency of poorly water-soluble compounds among hits in high-throughput drug screening campaigns is a major obstacle in drug discovery. Moreover, in vivo testing using conventional animal TB models, such as mice, is time consuming and costly, and represents a major bottleneck in lead compound discovery and development. Here, we report the use of the zebrafish embryo TB model for evaluating the in vivo toxicity and efficacy of five poorly water-soluble nitronaphthofuran derivatives, which were recently identified as possessing anti-TB activity in vitro. To aid solubilization, compounds were formulated in biocompatible polymeric micelles (PMs). Three of the five PM-formulated nitronaphthofuran derivatives showed low toxicity in vivo, significantly reduced bacterial burden and improved survival in infected zebrafish embryos. We propose the zebrafish embryo TB-model as a quick and sensitive tool for evaluating the in vivo toxicity and efficacy of new anti-TB compounds during early stages of drug development. Thus, this model is well suited for pinpointing promising compounds for further development.

Zebrafish Models for the Safety and Therapeutic Testing of Nanoparticles with a Focus on Macrophages

New nanoparticles and biomaterials are increasingly being used in biomedical research for drug delivery, diagnostic applications, or vaccines, and they are also present in numerous commercial products, in the environment and workplaces. Thus, the evaluation of the safety and possible therapeutic application of these nanomaterials has become of foremost importance for the proper progress of nanotechnology. Due to economical and ethical issues, in vitro and in vivo methods are encouraged for the testing of new compounds and/or nanoparticles, however in vivo models are still needed. In this scenario, zebrafish (Danio rerio) has demonstrated potential for toxicological and pharmacological screenings. Zebrafish presents an innate immune system, from early developmental stages, with conserved macrophage phenotypes and functions with respect to humans. This fact, combined with the transparency of zebrafish, the availability of models with fluorescently labelled macrophages, as well as a broad variety of disease models offers great possibilities for the testing of new nanoparticles. Thus, with a particular focus on macrophage-nanoparticle interaction in vivo, here, we review the studies using zebrafish for toxicological and biodistribution testing of nanoparticles, and also the possibilities for their preclinical evaluation in various diseases, including cancer and autoimmune, neuroinflammatory, and infectious diseases.

Bioinspired silk fibroin nano-delivery systems protect against 5-FU induced gastrointestinal mucositis in a mouse model and display antitumor effects on HT-29 colorectal cancer cells in vitro

Colorectal cancer (CRC), is the second cause of cancer-related deaths worldwide is one of the most prevalent types of cancers. Conventional treatment continues to rely on surgery, chemotherapy, and radiotherapy, but for advanced cases, adjuvant chemotherapy remains the main approach for improving surgical outcomes and lower the disease recurrence probability. Chemotherapy-induced gastrointestinal (GI) toxicity is the main dose-limiting factor for many chemotherapeutic regimens, including 5-FU, and one of the biggest oncological challenges. Up to 40% of the patients receiving 5-FU get mucositis, 10-15% of which develop severe symptoms. In this context, our study aimed to develop a bioinspired nanosized drug delivery system as a strategy to reduce 5-FU associated side effects, such as GI mucositis. To this end, SF-based nanoparticles were prepared and characterized in terms of size and morphology, as well as in terms of in vitro antitumoral activity on a biomimetic colorectal cancer model by investigation of apoptosis, DNA fragmentation, and release of reactive oxygen species. Additionally, the capacity of the SF-based nanocarriers to offer intestinal protection against 5-FU-induced GI mucositis was evaluated in vivo using a mouse model that mimics the chemotherapy-associated gut mucositis occurring in colorectal cancer. Our studies show that silk fibroin nanoparticles efficiently deliver 5-FU to tumor cells in vitro while protecting against drug-induced GI mucositis in a mouse model.

Non-Ionic Surfactants for Stabilization of Polymeric Nanoparticles for Biomedical Uses

Surfactants are essential in the manufacture of polymeric nanoparticles by emulsion formation methods and to preserve the stability of carriers in liquid media. The deposition of non-ionic surfactants at the interface allows a considerable reduction of the globule of the emulsion with high biocompatibility and the possibility of oscillating the final sizes in a wide nanometric range. Therefore, this review presents an analysis of the three principal non-ionic surfactants utilized in the manufacture of polymeric nanoparticles; polysorbates, poly(vinyl alcohol), and poloxamers. We included a section on general properties and uses and a comprehensive compilation of formulations with each principal non-ionic surfactant. Then, we highlight a section on the interaction of non-ionic surfactants with biological barriers to emphasize that the function of surfactants is not limited to stabilizing the dispersion of nanoparticles and has a broad impact on pharmacokinetics. Finally, the last section corresponds to a recommendation in the experimental approach for choosing a surfactant applying the systematic methodology of Quality by Design.

Appraisal of amiodarone-loaded PLGA nanoparticles for prospective safety and toxicity in a rat model

AIMS

Amiodarone (AM) is a highly efficient drug for arrhythmias treatment, but its extra-cardiac adverse effects offset its therapeutic efficacy. Nanoparticles (NPs)-based delivery system could provide a strategy to allow sustained delivery of AM to the myocardium and reduction of adverse effects. The primary purpose was to develop AM-loaded NPs and explore their ameliorative effects versus off-target toxicities.

MATERIALS AND METHODS

Polymeric NPs were prepared using poly lactic-co-glycolic acid and their physicochemical properties were characterized. Animal studies were conducted using a rat model to compare exposure to AM versus that of the AM-loaded NPs. Biochemical evaluation of liver enzymes, lipid profile, and thyroid hormones was achieved. Besides, histopathological changes in liver and lung were studied.

KEY FINDINGS

Under optimal experimental conditions, the AM-loaded NPs had a size of 186.90 nm and a negative zeta potential (-14.67 mV). Biochemical evaluation of AM-treated animal group showed a significant increase in cholesterol, TG, LDL, T4, and TSH levels (ρ < 0.05). Remarkably, the AM-treated group exhibited a significant increase of liver enzymes (ρ < 0.05) coupled with an obvious change in liver architecture. The AM-loaded NPs displayed a reduction of liver damage and enzyme levels. Lung sections of the AM-treated group demonstrated thickening of interalveolar septa, mononuclear cellular infiltration with congested blood vessels, and heavy collagenous fibers deposition. Conversely, less cellular infiltration and septal thickening were observed in the animal lungs treated with the AM-loaded NPs-treated.

SIGNIFICANCE

Our findings demonstrate the competence of the AM-loaded NPs to open several exciting avenues for evading the AM-induced off-target toxicities.

The Application of Nanotechnology for the Diagnosis and Treatment of Brain Diseases and Disorders

Brain is by far the most complex organ in the body. It is involved in the regulation of cognitive, behavioral, and emotional activities. The organ is also a target for many diseases and disorders ranging from injuries to cancers and neurodegenerative diseases. Brain diseases are the main causes of disability and one of the leading causes of deaths. Several drugs that have shown potential in improving brain structure and functioning in animal models face many challenges including the delivery, specificity, and toxicity. For many years, researchers have been facing challenge of developing drugs that can cross the physical (blood–brain barrier), electrical, and chemical barriers of the brain and target the desired region with few adverse events. In recent years, nanotechnology emerged as an important technique for modifying and manipulating different objects at the molecular level to obtain desired features. The technique has proven to be useful in diagnosis as well as treatments of brain diseases and disorders by facilitating the delivery of drugs and improving their efficacy. As the subject is still hot, and new research findings are emerging, it is clear that nanotechnology could upgrade health care systems by providing easy and highly efficient diagnostic and treatment methods. In this review, we will focus on the application of nanotechnology in the diagnosis and treatment of brain diseases and disorders by illuminating the potential of nanoparticles.

Preclinical Models of Nontuberculous Mycobacteria Infection for Early Drug Discovery and Vaccine Research

Nontuberculous mycobacteria (NTM) represent an increasingly prevalent etiology of soft tissue infections in animals and humans. NTM are widely distributed in the environment and while, for the most part, they behave as saprophytic organisms, in certain situations, they can be pathogenic, so much so that the incidence of NTM infections has surpassed that of Mycobacterium tuberculosis in developed countries. As a result, a growing body of the literature has focused attention on the critical role that drug susceptibility tests and infection models play in the design of appropriate therapeutic strategies against NTM diseases. This paper is an overview of the in vitro and in vivo models of NTM infection employed in the preclinical phase for early drug discovery and vaccine development. It summarizes alternative methods, not fully explored, for the characterization of anti-mycobacterial compounds.

Controlling Particle Size and Release Kinetics in the Sustained Delivery of Oral Antibiotics Using pH-Independent Mucoadhesive Polymers

Copolymers synthesized from acrylic acid and methacrylic acid used as gastroprotective and mucoadhesive enteric coatings have been used to prepare micro- (∼2 μm), submicro- (∼200 nm), and nanoparticles (∼20 nm) containing rifampicin (Rif) to obtain time-controlled drug release kinetics. Different particle sizes and drug release kinetics have been obtained using different synthesis conditions and fabrication techniques including the use of an electrosprayer and an interdigital microfabricated micromixer. The antimicrobial action of the encapsulated Rif has been demonstrated against Staphylococcus aureus ATCC 25923 and compared with the effect of the equivalent dose of the free macrolide antibiotic. At low concentrations, the encapsulated antibiotic showed superior antimicrobial activity than the free drug. The stability of the developed particles has been evaluated in vitro under simulated gastric and intestinal conditions. At the concentrations tested, a reduced cytotoxicity against different human cell lines was observed after analyzing their subcytotoxic doses and the influence on their cell cycle by flow cytometry. Drug release kinetics can be tuned by adjusting particle sizes, and it would be possible to reach the minimum inhibitory concentration or the minimum bactericidal concentration at different time points depending on the medical needs.

Polymersomes Eradicating Intracellular Bacteria

Mononuclear phagocytes such as monocytes, tissue-specific macrophages, and dendritic cells are primary actors in both innate and adaptive immunity. These professional phagocytes can be parasitized by intracellular bacteria, turning them from housekeepers to hiding places and favoring chronic and/or disseminated infection. One of the most infamous is the bacteria that cause tuberculosis (TB), which is the most pandemic and one of the deadliest diseases, with one-third of the world's population infected and an average of 1.8 million deaths/year worldwide. Here we demonstrate the effective targeting and intracellular delivery of antibiotics to infected macrophages both in vitro and in vivo, using pH-sensitive nanoscopic polymersomes made of PMPC-PDPA block copolymer. Polymersomes showed the ability to significantly enhance the efficacy of the antibiotics killing Mycobacterium bovis, Mycobacterium tuberculosis, and another established intracellular pathogen, Staphylococcus aureus. Moreover, they demonstrated to easily access TB-like granuloma tissues-one of the harshest environments to penetrate-in zebrafish models. We thus successfully exploited this targeting for the effective eradication of several intracellular bacteria, including M. tuberculosis, the etiological agent of human TB.

Real-time imaging of polymersome nanoparticles in zebrafish embryos engrafted with melanoma cancer cells: Localization, toxicity and treatment analysis

BACKGROUND

The developing zebrafish is an emerging tool in nanomedicine, allowing non-invasive live imaging of the whole animal at higher resolution than is possible in the more commonly used mouse models. In addition, several transgenic fish lines are available endowed with selected cell types expressing fluorescent proteins; this allows nanoparticles to be visualized together with host cells.

METHODS

Here, we introduce the zebrafish neural tube as a robust injection site for cancer cells, excellently suited for high resolution imaging. We use light and electron microscopy to evaluate cancer growth and to follow the fate of intravenously injected nanoparticles.

FINDINGS

Fluorescently labelled mouse melanoma B16 cells, when injected into this structure proliferated rapidly and stimulated angiogenesis of new vessels. In addition, macrophages, but not neutrophils, selectively accumulated in the tumour region. When injected intravenously, nanoparticles made of Cy5-labelled poly(ethylene glycol)-block-poly(2-(diisopropyl amino) ethyl methacrylate) (PEG-PDPA) selectively accumulated in the neural tube cancer region and were seen in individual cancer cells and tumour associated macrophages. Moreover, when doxorubicin was released from PEG-PDPA, in a pH dependant manner, these nanoparticles could strongly reduce toxicity and improve the treatment outcome compared to the free drug in zebrafish xenotransplanted with mouse melanoma B16 or human derived melanoma cells.

INTERPRETATION

The zebrafish has the potential of becoming an important intermediate step, before the mouse model, for testing nanomedicines against patient-derived cancer cells.

FUNDING

We received funding from the Norwegian research council and the Norwegian cancer society.

Thioridazine Is an Efflux Pump Inhibitor in Mycobacterium avium Complex but of Limited Clinical Relevance

Treatment of Mycobacterium avium complex pulmonary disease (MAC-PD) is challenging partly due to high efflux pump expression. Thioridazine might block these efflux pumps. We explore the efficacy of thioridazine against M. avium isolates using MICs, time-kill combination assays, ex vivo macrophage infection assays, and efflux assays. Thioridazine is bactericidal against M. avium, inhibits intracellular growth at 2× MIC, and blocks ethidium bromide efflux. However, its toxicity and low plasma concentrations make it unlikely to add efficacy to MAC-PD therapy.

Efflux pump inhibitors as a promising adjunct therapy against drug resistant tuberculosis: a new strategy to revisit mycobacterial targets and repurpose old drugs

INTRODUCTION

In 2018, an estimated 377,000 people developed multidrug-resistant tuberculosis (MDR-TB), urging for new effective treatments. In the last years, it has been accepted that efflux pumps play an important role in the evolution of drug resistance. Strategies are required to mitigate the consequences of the activity of efflux pumps.

AREAS COVERED

Based upon the literature available in PubMed, up to February 2020, on the diversity of efflux pumps in Mycobacterium tuberculosis and their association with drug resistance, studies that identified efflux inhibitors and their effect on restoring the activity of antimicrobials subjected to efflux are reviewed. These support a new strategy for the development of anti-TB drugs, including efflux inhibitors, using in silico drug repurposing.

EXPERT OPINION

The current literature highlights the contribution of efflux pumps in drug resistance in M. tuberculosis and that efflux inhibitors may help to ensure the effectiveness of anti-TB drugs. However, despite the usefulness of efflux inhibitors in in vitro studies, in most cases their application in vivo is restricted due to toxicity. In a time when new drugs are needed to fight MDR-TB and extensively drug-resistant TB, cost-effective strategies to identify safer efflux inhibitors should be implemented in drug discovery programs.

An Integrated In Vitro-In Silico Approach for Silver Nanoparticle Dosimetry in Cell Cultures

Potential human and environmental hazards resulting from the exposure of living organisms to silver nanoparticles (Ag NPs) have been the subject of intensive discussion in the last decade. Despite the growing use of Ag NPs in biomedical applications, a quantification of the toxic effects as a function of the total silver mass reaching cells (namely, target cell dose) is still needed. To provide a more accurate dose-response analysis, we propose a novel integrated approach combining well-established computational and experimental methodologies. We first used a particokinetic model (ISD3) for providing experimental validation of computed Ag NP sedimentation in static-cuvette experiments. After validation, ISD3 was employed to predict the total mass of silver reaching human endothelial cells and hepatocytes cultured in 96 well plates. Cell viability measured after 24 h of culture was then related to this target cell dose. Our results show that the dose perceived by the cell monolayer after 24 h of exposure is around 85% lower than the administered nominal media concentration. Therefore, accurate dosimetry considering particle characteristics and experimental conditions (e.g., time, size and shape of wells) should be employed for better interpreting effects induced by the amount of silver reaching cells.

Intramacrophage Delivery of Dual Drug Loaded Nanoparticles for Effective Clearance of Mycobacterium tuberculosis

The escalating global burden of tuberculosis necessitates radical strategies to curb its spread. In this study, rifampicin (RIF), a first line anti-tubercular antibiotic and curcumin (CUR), a promising antimycobacterial compound were co-encapsulated in polymeric nanoparticles to achieve intramacrophage delivery and improved Mycobacterium tuberculosis clearance. The dual loaded nanoparticles revealed average size ∼400 nm, low polydispersity and zeta potential of -26.89 ± 2.9 mV. Near complete release of both drugs from nanoparticles in artificial lysosomal fluid proposed drug release after macrophage internalisation. Nanoparticles were nontoxic to RAW 264.7 macrophages and aided 1.5-fold higher drug internalisation compared to free drugs. Enriched intracellular internalisation and lysosomal presence of nanoparticles was ascertained by confocal microscopy. Comparable minimum inhibitory concentration (MIC) of free RIF and CUR and nanoparticle encapsulated RIF and CUR confirmed retention of drug properties. High efficacy against Mycobacterium tuberculosis infected macrophages with RIF-CUR nanoparticles at 25× MIC (98.03 ± 2.5%), with complete clearance above 50× MIC suggests the dual loaded nanoparticles as a promising new nanosystem for tackling tuberculosis.

Zebrafish Embryos Allow Prediction of Nanoparticle Circulation Times in Mice and Facilitate Quantification of Nanoparticle-Cell Interactions

The zebrafish embryo is a vertebrate well suited for visualizing nanoparticles at high resolution in live animals. Its optical transparency and genetic versatility allow noninvasive, real-time observations of vascular flow of nanoparticles and their interactions with cells throughout the body. As a consequence, this system enables the acquisition of quantitative data that are difficult to obtain in rodents. Until now, a few studies using the zebrafish model have only described semiquantitative results on key nanoparticle parameters. Here, a MACRO dedicated to automated quantitative methods is described for analyzing important parameters of nanoparticle behavior, such as circulation time and interactions with key target cells, macrophages, and endothelial cells. Direct comparison of four nanoparticle (NP) formulations in zebrafish embryos and mice reveals that data obtained in zebrafish can be used to predict NPs' behavior in the mouse model. NPs having long or short blood circulation in rodents behave similarly in the zebrafish embryo, with low circulation times being a consequence of NP uptake into macrophages or endothelial cells. It is proposed that the zebrafish embryo has the potential to become an important intermediate screening system for nanoparticle research to bridge the gap between cell culture studies and preclinical rodent models such as the mouse.

Precise Drug Delivery by Using PLGA-Based Microspheres and Optical Manipulators

The accurate delivery of precise amounts of drugs to a specific location can considerably affect various clinical applications. The precise control of drug amount and position is crucial to a successful drug delivery. This paper proposes the use of poly(lactide-co-glycolicacid) (PLGA)-based microspheres to contain precise amounts of drugs and an optical tweezer manipulator to transport these drug-containing microspheres to their targeted sites in vivo. The drugs were delivered by the PLGA-based microspheres to the yolk sac of zebrafish embryos, and a sustained drug release was observed to examine the anti-angiogenesis and angiogenesis activities. The PLGA-based microspheres degraded in zebrafish, thereby verifying that these microspheres can be used as drug carriers in vivo to ensure good biocompatibility and biodegradation. The proposed precise drug delivery approach can be used in protein tests and drug property characterization in vivo.

Zebrafish as a preclinical in vivo screening model for nanomedicines

The interactions of nanomedicines with biological environments is heavily influenced by their physicochemical properties. Formulation design and optimization are therefore key steps towards successful nanomedicine development. Unfortunately, detailed assessment of nanomedicine formulations, at a macromolecular level, in rodents is severely limited by the restricted imaging possibilities within these animals. Moreover, rodent in vivo studies are time consuming and expensive, limiting the number of formulations that can be practically assessed in any one study. Consequently, screening and optimisation of nanomedicine formulations is most commonly performed in surrogate biological model systems, such as human-derived cell cultures. However, despite the time and cost advantages of classical in vitro models, these artificial systems fail to reflect and mimic the complex biological situation a nanomedicine will encounter in vivo. This has acutely hampered the selection of potentially successful nanomedicines for subsequent rodent in vivo studies. Recently, zebrafish have emerged as a promising in vivo model, within nanomedicine development pipelines, by offering opportunities to quickly screen nanomedicines under in vivo conditions and in a cost-effective manner so as to bridge the current gap between in vitro and rodent studies. In this review, we outline several advantageous features of the zebrafish model, such as biological conservation, imaging modalities, availability of genetic tools and disease models, as well as their various applications in nanomedicine development. Critical experimental parameters are discussed and the most beneficial applications of the zebrafish model, in the context of nanomedicine development, are highlighted.

Potentials of Host-Directed Therapies in Tuberculosis Management

Tuberculosis (TB) remains as a leading cause of mortality in developing countries, persisting as a major threat to the global public health. Current treatment involving a long antibiotic regimen brings concern to the topic of patient compliance, contributing to the emergence of drug resistant TB. The current review will provide an updated outlook on novel anti-TB therapies that can be given as adjunctive agents to current anti-TB treatments, with a particular focus on modulating the host immune response to effectively target all forms of TB. Additional potential therapeutic pathway targets, including lipid metabolism alteration and vascular endothelial growth factor (VEGF)-directed therapies, are discussed.

Matryoshka-type gastro-resistant microparticles for the oral treatment of Mycobacterium tuberculosis

AIM

Production of Matryoshka-type gastroresistant microparticles containing antibiotic-loaded poly lactic-co-glycolic acid (PLGA) nanoparticles (NP) against Mycobacterium tuberculosis.

MATERIALS & METHODS

The emulsification and evaporation methods were followed for the synthesis of PLGA-NPs and methacrylic acid-ethyl acrylate-based coatings to protect rifampicin from degradation under simulated gastric conditions.

RESULTS & CONCLUSION

The inner antibiotic-loaded NPs here reported can be released under simulated intestinal conditions whereas their coating protects them from degradation under simulated gastric conditions. The encapsulation does not hinder the antituberculosis action of the encapsulated antibiotic rifampicin. A sustained antibiotic release could be obtained when using the drug-loaded encapsulated NPs. Compared with the administration of the free drug, a more effective elimination of M. tuberculosis was observed when applying the NPs against infected macrophages. The antibiotic-loaded PLGA-NPs were also able to cross an in vitro model of intestinal barrier.

Cocktail Strategy Based on Spatio-Temporally Controlled Nano Device Improves Therapy of Breast Cancer

Metastatic breast cancer may be resistant to chemo-immunotherapy due to the existence of cancer stem cells (CSC). Also, the control of particle size and drug release of a drug carrier for multidrug combination is a key issue influencing the therapy effect. Here, a cocktail strategy is reported, in which chemotherapy against both bulk tumor cells and CSC and immune checkpoint blockade therapy are intergraded into one drug delivery system. The chemotherapeutic agent paclitaxel (PTX), the anti-CSC agent thioridazine (THZ), and the PD-1/PD-L1 inhibitor HY19991 (HY) are all incorporated into an enzyme/pH dual-sensitive nanoparticle with a micelle-liposome double-layer structure. The particle size shrinks when the nanoparticle transfers from circulation to tumor tissues, favoring both pharmacokinetics and cellular uptake, meanwhile achieving sequential drug release where needed. This nano device, named PM@THL, increases the intratumoral drug concentrations in mice and exhibits significant anticancer efficacy, with tumor inhibiting rate of 93.45% and lung metastasis suppression rate of 97.64%. It also reduces the proportion of CSC and enhances the T cells infiltration in tumor tissues, and thus prolongs the survival of mice. The cocktail therapy based on the spatio-temporally controlled nano device will be a promising strategy for treating breast cancer.

Polymeric curcumin nanoparticles by a facile in situ method for macrophage targeted delivery

Targeting macrophages is a promising strategy for improved therapy of intracellular infections as macrophages exhibit rapid phagocytosis of particles >200 nm. Entrapment of Curcumin (CUR) in nanocarriers could provide bioenhancement and macrophage targeting. We present a simple and facile in situ nanoprecipitation approach for instantaneous and on-site generation of curcumin nanoparticles (ISCurNP). ISCurNP optimised by Box-Behnken design exhibited average size of 208.25 ± 7.55 nm and entrapment efficiency of 90.16 ± 1.17%. Differential scanning calorimetry and X-Ray diffraction confirmed amorphization of CUR in ISCurNP. Sustained release was observed over 72 hr in vitro at lysosomal pH 4.5. Rapid and high uptake in RAW 264.7 macrophages was confirmed by flow cytometry and high performance liquid chromatography. Confocal microscopy established localisation of ISCurNP in lysosomal compartment. The facile in situ nanoprecipitation method provides simple, scalable technology to enable macrophage targeted delivery of CUR, with great promise for improved therapy of intracellular infections.

Fluorescence & bioluminescence in the quest for imaging, probing & analysis of mycobacterial infections

Mycobacterioses represent a global health problem and rapid diagnostic improvements are urgently required. Mycobacteria-specific fluorescence and bioluminescence phenomena have been found to be useful for a wide range of mycobacteria-focused research. Here, we present a critical survey of the most promising techniques in this field and the potential of new methods under investigation. These approaches include acid-fast staining, intrinsic fluorescence of the coenzyme F₄₂₀, fluorogenic substrates (e.g., β-lactamase-sensitive coumpounds) and recombination of mycobacteria or mycobacteriophages. Probably the most interesting and emerging host-inspecting approach is in vivo imaging. Detection of fluorescence in vivo, however, is complicated by light scattering, light absorption, and autofluorescence, caused by the tissues. Despite this, many of these systems show promise as the foundations for improved rapid analysis and imaging of mycobacterial infections, both in vitro and in vivo.

Detection of nanocarrier potentiation on drug induced phospholipidosis in cultured cells and primary hepatocyte spheroids by high content imaging and analysis

Considerable effort has been made to develop nanocarriers for controlled drug delivery over the last decade, while it remains unclear how the strength of adverse drug effect will be altered when a drug is loaded on the nanocarrier. Drug-induced phospholipidosis (DIP) is characterized with excessive accumulation of phospholipids in cells and is common for cationic amphiphilic drugs (CAD). Previously, we have reported that PEGylated graphene oxide (PEG-GO) loaded with several CAD can potentiate DIP. In current study, we extended our study on newly identified phospholipidosis (PLD) inducers that had been identified from the Library of Pharmacologically Active Compounds (LOPAC), to investigate if PEO-GO loaded with these CAD can alter DIP. Twenty-two CAD were respectively loaded on PEG-GO and incubated with RAW264.7, a macrophage cell line. The results showed that when a CAD was loaded on PEG-GO, its strength of PLD induction can be enhanced, unchanged or attenuated. PEG-GO loaded with Ifenprodil exhibited the highest PEG-GO potentiation effect compared to Ifenprodil treatment alone in RAW264.7 cells, and this effect was confirmed in human hepatocellular carcinoma HepG2, another cell line model for PLD induction. Primary hepatocyte culture and spheroids mimicking in vivo conditions were used to further validate nanocarrier potentiation on DIP by Ifenprodil. Stronger phospholipid accumulation was found in PEG-GO/Ifenprodil treated hepatocytes or spheroids than Ifenprodil treatment alone. Therefore, evidences were provided by us that nanocarriers may increase the adverse drug effects and guidance by regulatory agencies need to be drafted for the safe use of nanotechnology in drug delivery.

The Potential of Zebrafish as a Model Organism for Improving the Translation of Genetic Anticancer Nanomedicines

In the last few decades, the field of nanomedicine applied to cancer has revolutionized cancer treatment: several nanoformulations have already reached the market and are routinely being used in the clinical practice. In the case of genetic nanomedicines, i.e., designed to deliver gene therapies to cancer cells for therapeutic purposes, advances have been less impressive. This is because of the many barriers that limit the access of the therapeutic nucleic acids to their target site, and the lack of models that would allow for an improvement in the understanding of how nanocarriers can be tailored to overcome them. Zebrafish has important advantages as a model species for the study of anticancer therapies, and have a lot to offer regarding the rational development of efficient delivery of genetic nanomedicines, and hence increasing the chances of their successful translation. This review aims to provide an overview of the recent advances in the development of genetic anticancer nanomedicines, and of the zebrafish models that stand as promising tools to shed light on their mechanisms of action and overall potential in oncology.

Zebrafish as an early stage screening tool to study the systemic circulation of nanoparticulate drug delivery systems in vivo

Nanomedicines have gained much attention for the delivery of small molecules or nucleic acids as treatment options for many diseases. However, the transfer from experimental systems to in vivo applications remains a challenge since it is difficult to assess their circulation behavior in the body at an early stage of drug discovery. Thus, innovative and improved concepts are urgently needed to overcome this issue and to close the gap between empiric nanoparticle design, in vitro assessment, and first in vivo experiments using rodent animal models. This study was focused on the zebrafish as a vertebrate screening model to assess the circulation in blood and extravasation behavior of nanoparticulate drug delivery systems in vivo. To validate this novel approach, monodisperse preparations of fluorescently labeled liposomes with similar size and zeta potential were injected into transgenic zebrafish lines expressing green fluorescent protein in their vasculature. Phosphatidylcholine-based lipids differed by fatty acid chain length and saturation. Circulation behavior and vascular distribution pattern were evaluated qualitatively and semi-quantitatively using image analysis. Liposomes composed of lipids with lower transition temperature (<28°C) as well as PEGylated liposomes showed longer circulation times and extravasation. In contrast, liposomes composed of lipids with transition temperatures>28°C bound to venous parts of the vasculature. This circulation patterns in the zebrafish model did correlate with published and experimental pharmacokinetic data from mice and rats. Our findings indicate that the zebrafish model is a useful vertebrate screening tool for nanoparticulate drug delivery systems to predict their in vivo circulation behavior with respect to systemic circulation time and exposure.

Thioridazine: A Non-Antibiotic Drug Highly Effective, in Combination with First Line Anti-Tuberculosis Drugs, against Any Form of Antibiotic Resistance of Mycobacterium tuberculosis Due to Its Multi-Mechanisms of Action

This review presents the evidence that supports the use of thioridazine (TZ) for the therapy of a pulmonary tuberculosis infection regardless of its antibiotic resistance status. The evidence consists of in vitro and ex vivo assays that demonstrate the activity of TZ against all encountered Mycobacterium tuberculosis (Mtb) regardless of its antibiotic resistance phenotype, as well as in vivo as a therapy for mice infected with multi-drug resistant strains of Mtb, or for human subjects infected with extensively drug resistant (XDR) Mtb. The mechanisms of action by which TZ brings about successful therapeutic outcomes are presented in detail.

PLGA nanoparticles for intravitreal peptide delivery: statistical optimization, characterization and toxicity evaluation

Frequent intravitreal injections are currently used to overcome the ocular barriers and provide sufficient drug to the posterior eye segment. However, intravitreal injections have been associated with a number of complications and high treatment costs. To overcome these limitations, peptide-loaded poly(d,l-lactic-co-glycolic acid) nanoparticles (PLGA NPs) were developed using the nanoprecipitation technique and were optimized via Box-Behnken Design (BBD) and Response Surface Methodology (RSM). Developed NPs were evaluated for potential toxicity and cell apoptosis using the zebrafish embryo toxicity (ZET) model with titanium dioxide NPs and ethanol (1% v/v) serving as positive controls. Developed NPs had a size of 75.6-153.8 nm, a polydispersity index between 0.11 and 0.25 and a zeta potential of -9.4 to -46.0 mV. Loaded peptide was found to be stable under various experimental conditions tested. BBD and RSM were validated through the characterization of optimized formulations. Survival and hatching rates of NP-treated zebrafish 0-144 h post-fertilization were found to be normal with no significant malformations. Cellular apoptosis studies also endorsed the non-cytotoxic nature of the NPs. The overall results indicate that optimized PLGA nanoparticles could be a promising platform for efficient peptide delivery to the posterior segment of the eye.