Measurements of Deposition, Lung Surface Area and Lung Fluid for Simulation of Inhaled Compounds

"Isocyanates and isocyanides - life-threatening toxins or essential compounds?"

Isocyanides and isocyanates are some of the most reactive compounds in organic chemistry, making them perceived as compounds with high potential for use in both the laboratory and industry. With their high reactivity also comes several disadvantages, most notably their potentially high toxicity. The following article is a collection of information on the toxic effects of the isocyanide group on the human body and the environment. Information on the mechanism of how these harmful substances affect living tissues and the environment, worldwide information on how to protect against these chemicals, current regulations, and exposure limits for specific countries is compiled. The latest research on the application uses of isocyanates and isocyanides is also outlined, as well as the latest safer and greener methods and techniques to work with these compounds. Additionally, the presented article can serve as a brief guide to the organic toxicity of a group of isocyanates and isocyanates.

Development of a dry powder insufflation device with application in in vitro cell-based assays in the context of respiratory delivery

Research on pharmaceutical dry powders has been increasing worldwide, along with increased therapeutic strategies for an application through the pulmonary or the nasal routes. In vitro methodologies and tests that mimic the respiratory environment and the process of inhalation itself are, thus, essential. The literature frequently reports cell-based in vitro assays that involve testing the dry powders in suspension. This experimental setting is not adequate, as both the lung and the nasal cavity are devoid of abundant liquid. However, devices that permit powder insufflation over cells in culture are either scarce or technically complex and expensive, which is not feasible in early stages of research. In this context, this work proposes the development of a device that allows the delivery of dry powders onto cell surfaces, thus simulating inhalation more appropriately. Subsequently, a quartz crystal microbalance (QCM) was used to establish a technique enabling the determination of dry powder deposition profiles. Additionally, the determination of the viability of respiratory cells (A549) after the insufflation of a dry powder using the developed device was performed. In all, a prototype for dry powder insufflation was designed and developed, using 3D printing methods for its production. It allowed the homogenous dispersion of the insufflated powders over a petri dish and a QCM crystal, and a more detailed study on how dry powders disperse over the supports. The device, already protected by a patent, still requires further improvement, especially regarding the method for powder weighing and the efficiency of the insufflation process, which is being addressed. The impact of insufflation of air and of locust bean gum (LBG)-based microparticles revealed absence of cytotoxic effect, as cell viability roughly above 70 % was always determined.

Morphologic Features of Invasion in Lung Adenocarcinoma: Diagnostic Pitfalls

Reproducibility of pulmonary invasive adenocarcinoma diagnosis is poor when applying the World Health Organization (WHO) classification. In this article, we aimed first to explain by 3-dimensional morphology why simple pattern recognition induces pitfalls for the assessment of invasion as applied in the current WHO classification of pulmonary adenocarcinomas. The underlying iatrogenic-induced morphologic alterations in collapsed adenocarcinoma in situ overlap with criteria for invasive adenocarcinoma. Pitfalls in seemingly acinar and papillary carcinoma are addressed with additional cytokeratin 7 and elastin stains. In addition, we provide more stringent criteria for a better reproducible and likely generalizable classification.

Drug solubility in biorelevant media in the context of an inhalation-based biopharmaceutics classification system (iBCS)

An inhalation-based Biopharmaceutics Classification System for pulmonary drugs (iBCS) holds the perspective to allow for scientifically sound prediction of differences in the in vivo performance of orally inhaled drug products (OIDPs). A set of nine drug substances were selected, that are administered via both the oral and pulmonary routes. Their solubility was determined in media representative for the oral (Fasted State Simulated Intestinal Fluid (FaSSIF)) and pulmonary (Alveofact medium and Simulated Lung Fluid (SLF)) routes of administration to confirm the need for a novel approach for inhaled drugs. The complexity of these media was then stepwise reduced with the purpose of understanding the contribution of their components to the solubilizing capacity of the media. A second reason for varying the complexity was to identify a medium that would allow robust but accurate dissolution testing. Hence, Hank's balanced salt solution (HBSS) as a medium used in many in vitro biological tests, non-buffered saline solution, and water were included. For some drug substances (salbutamol sulfate, tobramycin, isoniazid, and tiotropium bromide), no significant differences were observed between the solubility in the media used. For other drugs, however, we observed either just small (rifampicin, budesonide, salmeterol) or unexpectedly large differences (beclomethasone dipropionate). Based on the minimum theoretical solubility required for their common pulmonary dose in 10 ml of lung lining fluid, drug solubility was classified as either high or low. Two high solubility and two low solubility compounds were then selected for refined solubility testing in pulmonary relevant media by varying their content of phospholipids, surfactant proteins and other proteins. The solubility of drug substances in simulated lung lining fluids was found to be dependent on the physicochemical properties of the drug substance and the composition of the media. While a pulmonary dissolution medium that would fit all drugs could not be established, our approach may provide guidance for finding the most suitable dissolution medium for a given drug substance and better designing in vitro tests for predicting the in vivo performance of inhalable drug products.

Epithelial MAPK signaling directs endothelial NRF2 signaling and IL-8 secretion in a tri-culture model of the alveolar-microvascular interface following diesel exhaust particulate (DEP) exposure

BACKGROUND

Particulate matter 2.5 (PM2.5) deposition in the lung's alveolar capillary region (ACR) is significantly associated with respiratory disease development, yet the molecular mechanisms are not completely understood. Adverse responses that promote respiratory disease development involve orchestrated, intercellular signaling between multiple cell types within the ACR. We investigated the molecular mechanisms elicited in response to PM2.5 deposition in the ACR, in an in vitro model that enables intercellular communication between multiple resident cell types of the ACR.

METHODS

An in vitro, tri-culture model of the ACR, incorporating alveolar-like epithelial cells (NCI-H441), pulmonary fibroblasts (IMR90), and pulmonary microvascular endothelial cells (HULEC) was developed to investigate cell type-specific molecular responses to a PM2.5 exposure in an in-vivo-like model. This tri-culture in vitro model was termed the alveolar capillary region exposure (ACRE) model. Alveolar epithelial cells in the ACRE model were exposed to a suspension of diesel exhaust particulates (DEP) (20 µg/cm2) with an average diameter of 2.5 µm. Alveolar epithelial barrier formation, and transcriptional and protein expression alterations in the directly exposed alveolar epithelial and the underlying endothelial cells were investigated over a 24 h DEP exposure.

RESULTS

Alveolar epithelial barrier formation was not perturbed by the 24 h DEP exposure. Despite no alteration in barrier formation, we demonstrate that alveolar epithelial DEP exposure induces transcriptional and protein changes in both the alveolar epithelial cells and the underlying microvascular endothelial cells. Specifically, we show that the underlying microvascular endothelial cells develop redox dysfunction and increase proinflammatory cytokine secretion. Furthermore, we demonstrate that alveolar epithelial MAPK signaling modulates the activation of NRF2 and IL-8 secretion in the underlying microvascular endothelial cells.

CONCLUSIONS

Endothelial redox dysfunction and increased proinflammatory cytokine secretion are two common events in respiratory disease development. These findings highlight new, cell-type specific roles of the alveolar epithelium and microvascular endothelium in the ACR in respiratory disease development following PM2.5 exposure. Ultimately, these data expand our current understanding of respiratory disease development following particle exposures and illustrate the utility of multicellular in vitro systems for investigating respiratory tract health.

Optimizing in vitro phage-ciprofloxacin combination formulation for respiratory therapy of multi-drug resistant Pseudomonas aeruginosa infections

Respiratory infection caused by multi-drug resistant (MDR) Pseudomonas aeruginosa is challenging to treat. In this study, we investigate the optimal dose of anti-pseudomonas phage PEV31 (103, 105, and 108 PFU/mL) combined with ciprofloxacin (ranging from 1/8× MIC to 8× MIC) to treat the MDR P. aeruginosa strain FADD1-PA001 using time-kill studies. We determined the impact of phage growth kinetics in the presence of ciprofloxacin through one-step growth analysis. Single treatments with either phage PEV31 or ciprofloxacin (except at 8× MIC) showed limited bactericidal efficiency, with bacterial regrowth observed at 48 h. The most effective treatments were PEV31 at multiplicity of infection (MOI) of 0.1 and 100 combined with ciprofloxacin at concentrations above 1× MIC, resulting in a >4 log10 reduction in bacterial counts. While the burst size of phage PEV31 was decreased with increasing ciprofloxacin concentration, robust antimicrobial effects were still maintained in the combination treatment. Aerosol samples collected from vibrating mesh nebulization of the combination formulation at phage MOI of 100 with 2× MIC effectively inhibited bacterial density. In summary, our combination treatments eradicated in vitro bacterial growth and sustained antimicrobial effects for 48 h. These results indicated the potential application of nebulization-based strategies for the combination treatment against MDR lung infections.

Ternary Dry Powder Agglomerate Inhalation Formulation of Melatonin With Air Jet Mixing to Improve In Vitro And In Vivo Performance

An improved agglomerate formulation with melatonin and fine lactose for dry powder inhalation using Turbuhaler® was developed. Co-grinding lactose with 1 % magnesium stearate prior to air jet mixing served as a key factor to improve the in vitro aerosolization and in vivo efficacy. Elevated mixing pressure facilitated the dispersion and homogenization of the cohesive mixture for even distribution of agglomerate size after spheroidization and subsequent higher emitted dose with lower variation. Magnesium stearate was employed as a tertiary component to adjust the interparticle force for better aerosolization. At optimized mixing pressure, co-grinding lactose with magnesium stearate before jet mixing displayed further improvement of fine particle fraction to 71.6 ± 3.1 %. The superior fine particle deposition efficiency contributed to rapid onset of action and a high bioavailability of 67.0 % after intratracheal administration to rats. Overall, an inhalable melatonin dry powder formulation exhibiting good aerosol property and lung deposition with clinical translation potential was developed.

Diesel exhaust particles induce polarization state-dependent functional and transcriptional changes in human monocyte-derived macrophages

Macrophage populations exist on a spectrum between the proinflammatory M1 and proresolution M2 states and have demonstrated the ability to reprogram between them after exposure to opposing polarization stimuli. Particulate matter (PM) has been repeatedly linked to worsening morbidity and mortality following respiratory infections and has been demonstrated to modify macrophage function and polarization. The purpose of this study was to determine whether diesel exhaust particles (DEP), a key component of airborne PM, would demonstrate polarization state-dependent effects on human monocyte-derived macrophages (hMDMs) and whether DEP would modify macrophage reprogramming. CD14+CD16- monocytes were isolated from the blood of healthy human volunteers and differentiated into macrophages with macrophage colony-stimulating factor (M-CSF). Resulting macrophages were left unpolarized or polarized into the proresolution M2 state before being exposed to DEP, M1-polarizing conditions (IFN-γ and LPS), or both and tested for phagocytic function, secretory profile, gene expression patterns, and bioenergetic properties. Contrary to previous reports, we observed a mixed M1/M2 phenotype in reprogrammed M2 cells when considering the broader range of functional readouts. In addition, we determined that DEP exposure dampens phagocytic function in all polarization states while modifying bioenergetic properties in M1 macrophages preferentially. Together, these data suggest that DEP exposure of reprogrammed M2 macrophages results in a highly inflammatory, highly energetic subpopulation of macrophages that may contribute to the poor health outcomes following PM exposure during respiratory infections.NEW & NOTEWORTHY We determined that reprogramming M2 macrophages in the presence of diesel exhaust particles (DEP) results in a highly inflammatory mixed M1/M2 phenotype. We also demonstrated that M1 macrophages are particularly vulnerable to particulate matter (PM) exposure as seen by dampened phagocytic function and modified bioenergetics. Our study suggests that PM causes reprogrammed M2 macrophages to become a highly energetic, highly secretory subpopulation of macrophages that may contribute to negative health outcomes observed in humans after PM exposure.

Development and characterization of a spray-dried inhalable ternary combination for the treatment of Pseudomonas aeruginosa biofilm infection in cystic fibrosis

Cystic fibrosis (CF) is an inherited lung disease characterised by the accumulation of thick layers of dried mucus in the lungs which serve as a nidus for chronic infection. Pseudomonas aeruginosa is the predominant cause of chronic lung infection in cystic fibrosis. The dense mucus coupled with biofilm formation hinder antibiotic penetration and prevent them from reaching their target. Mucoactive agents are recommended in the treatment of CF in combination with antibiotics. In spite of the extensive research in developing novel drug combinations for the treatment of lung infection in CF, to our knowledge, there is no study that combines antibiotic, antibiofilm and mucoactive agent in a single inhaled dry powder formulation. In the present study, we investigate the possibility of adding a mucoactive agent to our previously developed ciprofloxacinquercetin (antibiotic-antibiofilm) dry powder for inhalation. Three mucoactive agents, namely mannitol (MAN), N-acetyl-L-cysteine (NAC) and ambroxol hydrochloride (AMB), were investigated for this purpose. The ternary combinations were prepared via spray drying without the addition of excipients. All ternary combinations conserved or improved the antibacterial and biofilm inhibition activities of ciprofloxacin against P. aeruginosa (ATCC 10145). The addition of AMB resulted in an amorphous ternary combination (SD-CQA) with superior physical stability as indicated by DSC and nonambient XRPD. Furthermore, SD-CQA displayed better in vitro aerosolization performance (ED ∼ 71 %; FPF ∼ 49 %) compared to formulations containing MAN and NAC (ED ∼ 64 % and 44 %; FPF ∼ 44 % and 29 %, respectively). In conclusion, a ternary drug combination powder with suitable aerosolization, physical stability and antibacterial/antibiofilm properties was prepared by a single spray drying step.

Detection of early (T1) lung cancers and lepidic adenocarcinomas in sputum and bronchial cytology

BACKGROUND

The lung is an extensively epithelialized organ, producing ample exfoliated material for sputum and bronchial cytology. In view of the updates in the World Health Organization classification of early (T1/≤ 3 cm) lung cancer with respect to adenocarcinomas with lepidic pattern, this study retrospectively reviews sputum and bronchial cytology paired with resection-confirmed lung cancers.

METHODS

A computerized search for all lung resection specimens of carcinomas over a 20-year period was performed. Cytologic diagnoses of corresponding sputum and bronchial cytology were classified into five-tiered categories (C1-insufficient/inadequate, C2-benign, C3-atypia, C4-suspicious and C5-malignant). Reports and slides of the resection specimen were reviewed for reclassification of T1 cancers.

RESULTS

Totally 472 and 383 sputum and bronchial cytology specimens respectively were included. Sensitivity for T1 lesions on sputum cytology were 10.6 %, 2.1 % and 0.5 % at cutoffs of atypia/C3, suspicious/C4 and malignant/C5 categories, lower than bronchial cytology (35.1 %, 15.5 %, 8.1 %; p < 0.001). T1 lesions correlated with lower detection rates, whereas squamous cell carcinoma histology, larger size and bronchial invasion were associated with increased detection rates in sputum and bronchial cytology (p < 0.050). Detection rates for abrasive bronchial cytology (brushing) were overall higher (p = 0.018- < 0.001), but on subgroup comparison, non-abrasive (aspiration, lavage and washing) cytology demonstrated favorable trends (p = 0.063-0.088) in detecting T1 lesions. Adenocarcinomas with lepidic pattern had lower suspicious/C4 (p = 0.040) or above and malignant/C5 (p = 0.019), but not atypia/C3 or above (p = 0.517) rates.

CONCLUSIONS

Most adenocarcinomas with lepidic pattern are only diagnosed as atypia/C3 on cytology. With its modest sensitivity, interpretation of negative and indeterminate cytology results mandates caution.

Systemically Administered Anti-uPAR Antibody Plasma and Lung ELF Pharmacokinetics Characterized by Minimal Lung PBPK Model

Antibody-based therapeutics have recently gained keen attention for the treatment of pulmonary indications. However, systemically administered antibody exposure in the lungs needs to be better understood and remains a topic of interest. In this study, we evaluated the exposure of two different uPAR (urokinase-type plasminogen activator receptor) targeting full-length monoclonal IgGs in plasma and lung epithelial lining fluid (ELF) of mice after IP and IV administration. Antibody AK17 exhibited linear pharmacokinetics (PK) in plasma and ELF at 3 and 30 mg/kg single IV dose. The average plasma and ELF half-lives for AK17 and AK21 ranged between ~321-411 h and ~230-345 h, respectively, indicating sustained systemic and lung exposure of antibodies. The average ELF to the plasma concentration ratio of antibodies was ~0.01 and ~0.03 with IP and IV dosing, respectively, over 2 weeks post single dose. We simultaneously characterized plasma and ELF PK of antibody in mice by developing a minimal lung PBPK model for antibody. This model reasonably captured the plasma and ELF PK data while estimating three parameters. The model accounts for the convective transport of antibody into the tissues via blood and lymph flow. FcRn-mediated transcytosis was incorporated into the model for antibody distribution across the lung epithelial barrier. This model serves as a platform to predict the pulmonary PK of systemically administered antibodies and to support optimal dose selection for desired exposure in the lungs as the site of action.

Pathogenesis of Aerosolized Ebola Virus Variant Makona in Nonhuman Primates

BACKGROUND

Highly pathogenic filoviruses such as Ebola virus (EBOV) hold capacity for delivery by artificial aerosols, and thus potential for intentional misuse. Previous studies have shown that high doses of EBOV delivered by small-particle aerosol cause uniform lethality in nonhuman primates (NHPs), whereas only a few small studies have assessed lower doses in NHPs.

METHODS

To further characterize the pathogenesis of EBOV infection via small-particle aerosol, we challenged cohorts of cynomolgus monkeys with low doses of EBOV variant Makona, which may help define risks associated with small particle aerosol exposures.

RESULTS

Despite using challenge doses orders of magnitude lower than previous studies, infection via this route was uniformly lethal across all cohorts. Time to death was delayed in a dose-dependent manner between aerosol-challenged cohorts, as well as in comparison to animals challenged via the intramuscular route. Here, we describe the observed clinical and pathological details including serum biomarkers, viral burden, and histopathological changes leading to death.

CONCLUSIONS

Our observations in this model highlight the striking susceptibility of NHPs, and likely humans, via small-particle aerosol exposure to EBOV and emphasize the need for further development of diagnostics and postexposure prophylactics in the event of intentional release via deployment of an aerosol-producing device.

Effects of vocal fold adduction on the particle deposition in the glottis: A numerical analysis and in vitro assessment

BACKGROUND

The efficacy of inhalation therapy depends on the drug deposition in the human respiratory tract. This study investigates the effects of vocal fold adduction on the particle deposition in the glottis.

METHODS

A realistic mouth-throat (MT) geometry was built based on CT images of a healthy adult (MT-A). Mild (MT-B) and great (MT-C) vocal fold (VF) adduction were incorporated in the original model. Monodisperse particles range in size from 3 to 12 μm were simulated at inspiration flow rates of 15, 30 and 45 L per minute (LPM). The regional deposition of drug aerosols was performed in 3D-printed models and quantified using high-performance liquid chromatography.

RESULTS

Both the numerical analysis and in vitro experiments show that most particles are deposited in the mouth, pharynx and supraglottis, while few are deposited in the glottis and subglottis. For most cases in MT-A, the particle quantity in glottis is lower than 0.02 N/mm2 at 15 and 30 LPM while they increase dramatically at 45 LPM. It peaked at 0.347 N/mm2 for 5-μm particles at 45 LPM in MT-B and 2.324 N/mm2 for 6-μm particles at 30 LPM in MT-C. The lowest drug mass faction in the glottis in vitro were found at 15 LPM for MT-A and MT-C, and at 30 LPM for MT-B, whereas it peaked at 45 LPM for all MT models, 0.71% in MT-A, 1.16% in MT-B, and 2.53% in MT-C, respectively.

CONCLUSION

Based on the results of this study, larger particles are more likely to be deposited in the oral cavity, oropharynx, and supraglottis than in the glottis. However, particle deposition in the glottis generally increases with VF adduction and greater inspiratory flow rates.

Climate change, air quality, and respiratory health: a focus on particle deposition in the lungs

This review article delves into the multifaceted relationship between climate change, air quality, and respiratory health, placing a special focus on the process of particle deposition in the lungs. We discuss the capability of climate change to intensify air pollution and alter particulate matter physicochemical properties such as size, dispersion, and chemical composition. These alterations play a significant role in influencing the deposition of particles in the lungs, leading to consequential respiratory health effects. The review paper provides a broad exploration of climate change's direct and indirect role in modifying particulate air pollution features and its interaction with other air pollutants, which may change the ability of particle deposition in the lungs. In conclusion, climate change may play an important role in regulating particle deposition in the lungs by changing physicochemistry of particulate air pollution, therefore, increasing the risk of respiratory disease development.

In Vitro high-throughput toxicological assessment of E-cigarette flavors on human bronchial epithelial cells and the potential involvement of TRPA1 in cinnamon flavor-induced toxicity

Electronic cigarettes (ECs) are considered a less hazardous alternative to tobacco smoking but are not harmless. Growing concerns about the safety profiles of flavors in e-liquids underpin the need for this study. Here, we screened 53 nicotine-free flavored e-liquids (across 15 flavor categories) across a 3-point concentration range (0.25%, 0.5%, and 1% v/v) in a high-throughput fashion in human bronchial epithelial (HBEC-3KT) submerged cell cultures to identify 'toxic hits' using in vitro endpoint assays comprising cell count, cell viability, and lactate dehydrogenase (LDH). We observed significant, dose-dependent adverse effects only with cinnamon, vanilla tobacco, and hazelnut e-liquids compared to media-only and PG/VG vehicle controls. Hence, we further analyzed these three flavors for their effects on HBEC-3KT proliferation, mitochondrial health, and oxidative stress. A significant decrease in cell proliferation after 36 h was observed for each e-liquid toxic hit compared to media-only and PG/VG controls. Hazelnut (at all concentrations) and vanilla tobacco (1%) increased cytoplasmic reactive oxygen species generation compared to media-only and PG/VG controls. Conversely, all three flavors at 0.5% and 1% significantly decreased mitochondrial membrane potential compared to PG/VG and media-only controls. Chemical analysis revealed that all three flavors contained volatile organic compounds. We hypothesized that the cytotoxicity of cinnamon might be mediated via TRPA1; however, TRPA1 antagonist AP-18 (10 μM) did not mitigate these effects, and cinnamon significantly increased TRPA1 transcript levels. Therefore, pathways mediating cinnamon's cytotoxicity warrant further investigations. This study could inform public health authorities on the relative health risks assessment following exposure to EC flavor ingredients.

An IgM-like inhalable ACE2 fusion protein broadly neutralizes SARS-CoV-2 variants

Many of the currently available COVID-19 vaccines and therapeutics are not effective against newly emerged SARS-CoV-2 variants. Here, we developed the metallo-enzyme domain of angiotensin converting enzyme 2 (ACE2)-the cellular receptor of SARS-CoV-2-into an IgM-like inhalable molecule (HH-120). HH-120 binds to the SARS-CoV-2 Spike (S) protein with high avidity and confers potent and broad-spectrum neutralization activity against all known SARS-CoV-2 variants of concern. HH-120 was developed as an inhaled formulation that achieves appropriate aerodynamic properties for rodent and monkey respiratory system delivery, and we found that early administration of HH-120 by aerosol inhalation significantly reduced viral loads and lung pathology scores in male golden Syrian hamsters infected by the SARS-CoV-2 ancestral strain (GDPCC-nCoV27) and the Delta variant. Our study presents a meaningful advancement in the inhalation delivery of large biologics like HH-120 (molecular weight (MW) ~ 1000 kDa) and demonstrates that HH-120 can serve as an efficacious, safe, and convenient agent against SARS-CoV-2 variants. Finally, given the known role of ACE2 in viral reception, it is conceivable that HH-120 has the potential to be efficacious against additional emergent coronaviruses.

Food and Drug Administration Public Workshop Summary-Development Considerations of Antifungal Drugs to Address Unmet Medical Need

Pressing challenges in the treatment of invasive fungal infections (IFIs) include emerging and rare pathogens, resistant/refractory infections, and antifungal armamentarium limited by toxicity, drug-drug interactions, and lack of oral formulations. Development of new antifungal drugs is hampered by the limitations of the available diagnostics, clinical trial endpoints, prolonged trial duration, difficulties in patient recruitment, including subpopulations (eg, pediatrics), and heterogeneity of the IFIs. On 4 August 2020, the US Food and Drug Administration convened a workshop that included IFI experts from academia, industry, and other government agencies to discuss the IFI landscape, unmet need, and potential strategies to facilitate the development of antifungal drugs for treatment and prophylaxis. This article summarizes the key topics presented and discussed during the workshop, such as incentives and research support for drug developers, nonclinical development, clinical trial design challenges, lessons learned from industry, and potential collaborations to facilitate antifungal drug development.

Low-dose intrapulmonary drug delivery device for studies on next-generation therapeutics in mice

Although nebulizers have been developed for delivery of small molecules in human patients, no tunable device has been purpose-built for targeted delivery of modern large molecule and temperature-sensitive therapeutics to mice. Mice are used most of all species in biomedical research and have the highest number of induced models for human-relevant diseases and transgene models. Regulatory approval of large molecule therapeutics, including antibody therapies and modified RNA highlight the need for quantifiable dose delivery in mice to model human delivery, proof-of-concept studies, efficacy, and dose-response. To this end, we developed and characterized a tunable nebulization system composed of an ultrasonic transducer equipped with a mesh nebulizer fitted with a silicone restrictor plate modification to control the nebulization rate. We have identified the elements of design that influence the most critical factors to targeted delivery to the deep lungs of BALB/c mice. By comparing an in silico model of the mouse lung with experimental data, we were able to optimize and confirm the targeted delivery of over 99% of the initial volume to the deep portions of the mouse lung. The resulting nebulizer system provides targeted lung delivery efficiency far exceeding conventional nebulizers preventing waste of expensive biologics and large molecules during proof-of-concept and pre-clinical experiments involving mice. (Word Count =207).

Development of a Minimalistic Physiologically Based Pharmacokinetic (mPBPK) Model for the Preclinical Development of Spectinamide Antibiotics

Spectinamides 1599 and 1810 are lead spectinamide compounds currently under preclinical development to treat multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. These compounds have previously been tested at various combinations of dose level, dosing frequency, and route of administration in mouse models of Mycobacterium tuberculosis (Mtb) infection and in healthy animals. Physiologically based pharmacokinetic (PBPK) modeling allows the prediction of the pharmacokinetics of candidate drugs in organs/tissues of interest and extrapolation of their disposition across different species. Here, we have built, qualified, and refined a minimalistic PBPK model that can describe and predict the pharmacokinetics of spectinamides in various tissues, especially those relevant to Mtb infection. The model was expanded and qualified for multiple dose levels, dosing regimens, routes of administration, and various species. The model predictions in mice (healthy and infected) and rats were in reasonable agreement with experimental data, and all predicted AUCs in plasma and tissues met the two-fold acceptance criteria relative to observations. To further explore the distribution of spectinamide 1599 within granuloma substructures as encountered in tuberculosis, we utilized the Simcyp granuloma model combined with model predictions in our PBPK model. Simulation results suggest substantial exposure in all lesion substructures, with particularly high exposure in the rim area and macrophages. The developed model may be leveraged as an effective tool in identifying optimal dose levels and dosing regimens of spectinamides for further preclinical and clinical development.

MMP-3-mediated cleavage of OPN is involved in copper oxide nanoparticle-induced activation of fibroblasts

BACKGROUND

Copper oxide nanoparticles (Nano-CuO) are one of the most produced and used nanomaterials. Previous studies have shown that exposure to Nano-CuO caused acute lung injury, inflammation, and fibrosis. However, the mechanisms underlying Nano-CuO-induced lung fibrosis are still unclear. Here, we hypothesized that exposure of human lung epithelial cells and macrophages to Nano-CuO would upregulate MMP-3, which cleaved osteopontin (OPN), resulting in fibroblast activation and lung fibrosis.

METHODS

A triple co-culture model was established to explore the mechanisms underlying Nano-CuO-induced fibroblast activation. Cytotoxicity of Nano-CuO on BEAS-2B, U937* macrophages, and MRC-5 fibroblasts were determined by alamarBlue and MTS assays. The expression or activity of MMP-3, OPN, and fibrosis-associated proteins was determined by Western blot or zymography assay. Migration of MRC-5 fibroblasts was evaluated by wound healing assay. MMP-3 siRNA and an RGD-containing peptide, GRGDSP, were used to explore the role of MMP-3 and cleaved OPN in fibroblast activation.

RESULTS

Exposure to non-cytotoxic doses of Nano-CuO (0.5 and 1 µg/mL) caused increased expression and activity of MMP-3 in the conditioned media of BEAS-2B and U937* cells, but not MRC-5 fibroblasts. Nano-CuO exposure also caused increased production of cleaved OPN fragments, which was abolished by MMP-3 siRNA transfection. Conditioned media from Nano-CuO-exposed BEAS-2B, U937*, or the co-culture of BEAS-2B and U937* caused activation of unexposed MRC-5 fibroblasts. However, direct exposure of MRC-5 fibroblasts to Nano-CuO did not induce their activation. In a triple co-culture system, exposure of BEAS-2B and U937* cells to Nano-CuO caused activation of unexposed MRC-5 fibroblasts, while transfection of MMP-3 siRNA in BEAS-2B and U937* cells significantly inhibited the activation and migration of MRC-5 fibroblasts. In addition, pretreatment with GRGDSP peptide inhibited Nano-CuO-induced activation and migration of MRC-5 fibroblasts in the triple co-culture system.

CONCLUSIONS

Our results demonstrated that Nano-CuO exposure caused increased production of MMP-3 from lung epithelial BEAS-2B cells and U937* macrophages, which cleaved OPN, resulting in the activation of lung fibroblasts MRC-5. These results suggest that MMP-3-cleaved OPN may play a key role in Nano-CuO-induced activation of lung fibroblasts. More investigations are needed to confirm whether these effects are due to the nanoparticles themselves and/or Cu ions.

Pharmacokinetics comparison of vardenafil as administered by an intranasal spray formulation vs a 10-mg oral tablet

BACKGROUND

Oral vardenafil (VDF) tablet is an effective treatment for erectile dysfunction (ED), but intranasal administration with a suitable formulation can lead to a faster onset of action and offer more convenient planning for ED treatment.

AIM

The primary purpose of the present pilot clinical study was to determine whether intranasal VDF with an alcohol-based formulation can result in more "user-friendly pharmacokinetics" as compared with oral tablet administration.

METHODS

This single-dose randomized crossover study was conducted in 12 healthy young volunteers receiving VDF as a 10-mg oral tablet or 3.38-mg intranasal spray. Multiple blood concentrations were obtained, and VDF concentrations were determined with a liquid chromatography-tandem mass spectrometry assay. Pharmacokinetic parameters following each treatment were compared and adverse events assessed.

OUTCOMES

Pharmacokinetic parameters were obtained: apparent elimination rate constant, elimination half-life, peak concentration, peak time, total area under the curve, and relative bioavailability.

RESULTS

Although mean apparent elimination rate constant, elimination half-life, peak concentration, and total area under the curve were similar between intranasal and oral administration, the median peak time from intranasal was much shorter (10 vs 58 minutes, P < .001, Mann-Whitney U test). The variability of the pharmacokinetic parameters was also less with intranasal than oral administration. The relative bioavailability of intranasal to oral was 1.67. Intranasal VDF caused transient but tolerable local nasal reactions in 50% of subjects. Other adverse events (eg, headache) were similar between the treatments. The incidence of adverse events was, however, significantly less in the second treatment after initial exposure to VDF. No serious adverse events were noted.

CLINICAL IMPLICATIONS

Intranasal VDF potentially offers a more timely and lower dose for the treatment of ED in patients who can tolerate the transient local adverse reactions.

STRENGTHS AND LIMITATIONS

The strength of this study is its randomized crossover design. Because the study was conducted in 12 healthy young subjects, the results may not reflect those observed in elderly patients who may be likely taking VDF for ED. Nevertheless, the changes of pharmacokinetic parameters in the present study are likely a reflection of the differences between intranasal and oral administration of the formulations.

CONCLUSION

Our study indicated that the present VDF formulation, when administered intranasally, can achieve a more rapid but similar plasma concentration with only about one-third dose when compared with the oral administration.

Immunomodulatory Properties of Vitamin D in the Intestinal and Respiratory Systems

Vitamin D plays a crucial role in modulating the innate immune response by interacting with its intracellular receptor, VDR. In this review, we address vitamin D/VDR signaling and how it contributes to the regulation of intestinal and respiratory microbiota. We additionally review some components of the innate immune system, such as the barrier function of the pulmonary and intestinal epithelial membranes and secretion of mucus, with their respective modulation by vitamin D. We also explore the mechanisms by which this vitamin D/VDR signaling mounts an antimicrobial response through the transduction of microbial signals and the production of antimicrobial peptides that constitute one of the body’s first lines of defense against pathogens. Additionally, we highlight the role of vitamin D in clinical diseases, namely inflammatory bowel disease and acute respiratory distress syndrome, where excessive inflammatory responses and dysbiosis are hallmarks. Increasing evidence suggests that vitamin D supplementation may have potentially beneficial effects on those diseases.

Assessment of Carbon Nanotubes on Barrier Function, Ciliary Beating Frequency and Cytokine Release in In Vitro Models of the Respiratory Tract

The exposure to inhaled carbon nanotubes (CNT) may have adverse effects on workers upon chronic exposure. In order to assess the toxicity of inhaled nanoparticles in a physiologically relevant manner, an air-liquid interface culture of mono and cocultures of respiratory cells and assessment in reconstructed bronchial and alveolar tissues was used. The effect of CNT4003 reference particles applied in simulated lung fluid was studied in bronchial (Calu-3 cells, EpiAirway™ and MucilAir™ tissues) and alveolar (A549 +/-THP-1 and EpiAlveolar™ +/-THP-1) models. Cytotoxicity, transepithelial electrical resistance, interleukin 6 and 8 secretion, mucociliary clearance and ciliary beating frequency were used as readout parameters. With the exception of increased secretion of interleukin 6 in the EpiAlveolar™ tissues, no adverse effects of CNT4003 particles, applied at doses corresponding to the maximum estimated lifetime exposure of workers, in the bronchial and alveolar models were noted, suggesting no marked differences between the models. Since the doses for whole-life exposure were applied over a shorter time, it is not clear if the interleukin 6 increase in the EpiAlveolar™ tissues has physiological relevance.

Inhalation of virus-loaded droplets as a clinically plausible pathway to deep lung infection

Respiratory viruses, such as SARS-CoV-2, preliminarily infect the nasopharyngeal mucosa. The mechanism of infection spread from the nasopharynx to the deep lung-which may cause a severe infection-is, however, still unclear. We propose a clinically plausible mechanism of infection spread to the deep lung through droplets, present in the nasopharynx, inhaled and transported into the lower respiratory tract. A coupled mathematical model of droplet, virus transport and virus infection kinetics is exercised to demonstrate clinically observed times to deep lung infection. The model predicts, in agreement with clinical observations, that severe infection can develop in the deep lung within 2.5-7 days of initial symptom onset. Results indicate that while fluid dynamics plays an important role in transporting the droplets, infection kinetics and immune responses determine infection growth and resolution. Immune responses, particularly antibodies and T-lymphocytes, are observed to be critically important for preventing infection severity. This reinforces the role of vaccination in preventing severe infection. Managing aerosolization of infected nasopharyngeal mucosa is additionally suggested as a strategy for minimizing infection spread and severity.

Prominent toxicity of isocyanates and maleic anhydrides to Caenorhabditis elegans: Multilevel assay for typical organic additives of biodegradable plastics

Biodegradable plastics (BDP) are increasingly applied; however, there has been of concerns about their environmental safety, especially from nondegradable additive compositions. Until now, data of ecotoxicity of BDP additives is scarce. Here, nematode C. elegans was used to comparatively evaluate toxicity of an isocyanate additive, i.e., Hexamethylene diisocyanate (HDI), a maleic anhydride, i.e., Diallyl maleate (DIM), and other four BDP organic additives. These additives caused lethality of nematodes at µg L^-1 level, of lowest LC₅₀ value of HDI/DIM. Uniform exposure to these additives resulted in various degrees of inhibitions in body volumes and longevity, indicating developmental toxicity. Moreover, BDP additives induced significant elevations of gst-4 expression, especially mean 123.54 %/234.29 % increase in HDI/DIM group, but reduced ges-1 expression, which indicates oxidative damages and mitochondrial dysfunction. BDP additives further caused inhibition in locomotor and food intake/excretion behavior, and related damages of glutamatergic neurons and GABAergic neurons, indicating their neurotoxicity. We found HDI and DIM presented relatively strong effects on susceptible endpoints including lethality, gst-4, mean lifespan, food intake and excretion behavior. Overall, this study suggests prominent ecotoxic risk of isocyanates and maleic anhydrides as BDP additives, which is significant for the selection of environmentally friendly BDP additives.

Surfactant protein A alters endosomal trafficking of influenza A virus in macrophages

Influenza A virus infection (IAV) often leads to acute lung injury that impairs breathing and can lead to death, with disproportionate mortality in children and the elderly. Surfactant Protein A (SP-A) is a calcium-dependent opsonin that binds a variety of pathogens to help control pulmonary infections by alveolar macrophages. Alveolar macrophages play critical roles in host resistance and susceptibility to IAV infection. The effect of SP-A on IAV infection and antiviral response of macrophages, however, is not understood. Here, we report that SP-A attenuates IAV infection in a dose-dependent manner at the level of endosomal trafficking, resulting in infection delay in a model macrophage cell line. The ability of SP-A to suppress infection was independent of its glycosylation status. Binding of SP-A to hemagglutinin did not rely on the glycosylation status or sugar binding properties of either protein. Incubation of either macrophages or IAV with SP-A slowed endocytic uptake rate of IAV. SP-A interfered with binding to cell membrane and endosomal exit of the viral genome as indicated by experiments using isolated cell membranes, an antibody recognizing a pH-sensitive conformational epitope on hemagglutinin, and microscopy. Lack of SP-A in mice enhanced IFNβ expression, viral clearance and reduced mortality from IAV infection. These findings support the idea that IAV is an opportunistic pathogen that co-opts SP-A to evade host defense by alveolar macrophages. Our study highlights novel aspects of host-pathogen interactions that may lead to better understanding of the local mechanisms that shape activation of antiviral and inflammatory responses to viral infection in the lung.

A multiplex inhalation platform to model in situ like aerosol delivery in a breathing lung-on-chip

Prolonged exposure to environmental respirable toxicants can lead to the development and worsening of severe respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and fibrosis. The limited number of FDA-approved inhaled drugs for these serious lung conditions has led to a shift from in vivo towards the use of alternative in vitro human-relevant models to better predict the toxicity of inhaled particles in preclinical research. While there are several inhalation exposure models for the upper airways, the fragile and dynamic nature of the alveolar microenvironment has limited the development of reproducible exposure models for the distal lung. Here, we present a mechanistic approach using a new generation of exposure systems, the Cloud α AX12. This novel in vitro inhalation tool consists of a cloud-based exposure chamber (VITROCELL) that integrates the breathing ^AXLung-on-chip system (AlveoliX). The ultrathin and porous membrane of the AX12 plate was used to create a complex multicellular model that enables key physiological culture conditions: the air-liquid interface (ALI) and the three-dimensional cyclic stretch (CS). Human-relevant cellular models were established for a) the distal alveolar-capillary interface using primary cell-derived immortalized alveolar epithelial cells (^AXiAECs), macrophages (THP-1) and endothelial (HLMVEC) cells, and b) the upper-airways using Calu3 cells. Primary human alveolar epithelial cells (^AXhAEpCs) were used to validate the toxicity results obtained from the immortalized cell lines. To mimic in vivo relevant aerosol exposures with the Cloud α AX12, three different models were established using: a) titanium dioxide (TiO2) and zinc oxide nanoparticles b) polyhexamethylene guanidine a toxic chemical and c) an anti-inflammatory inhaled corticosteroid, fluticasone propionate (FL). Our results suggest an important synergistic effect on the air-blood barrier sensitivity, cytotoxicity and inflammation, when air-liquid interface and cyclic stretch culture conditions are combined. To the best of our knowledge, this is the first time that an in vitro inhalation exposure system for the distal lung has been described with a breathing lung-on-chip technology. The Cloud α AX12 model thus represents a state-of-the-art pre-clinical tool to study inhalation toxicity risks, drug safety and efficacy.

Opportunistic etiological agents causing lung infections: emerging need to transform lung-targeted delivery

Lung diseases continue to draw considerable attention from biomedical and public health care agencies. The lung with the largest epithelial surface area is continuously exposed to the external environment during exchanging gas. Therefore, the chances of respiratory disorders and lung infections are overgrowing. This review has covered promising and opportunistic etiologic agents responsible for lung infections. These pathogens infect the lungs either directly or indirectly. However, it is difficult to intervene in lung diseases using available oral or parenteral antimicrobial formulations. Many pieces of research have been done in the last two decades to improve inhalable antimicrobial formulations. However, very few have been approved for human use. This review article discusses the approved inhalable antimicrobial agents (AMAs) and identifies why pulmonary delivery is explored. Additionally, the basic anatomy of the respiratory system linked with barriers to AMA delivery has been discussed here. This review opens several new scopes for researchers to work on pulmonary medicines for specific diseases and bring more respiratory medication to market.

Physiologically-based pharmacokinetic model for pulmonary disposition of protein therapeutics in humans

Lung related disorders like COPD and Asthma, as well as various infectious diseases, form a major therapeutic area which would benefit from a predictive and adaptable mathematical model for describing pulmonary disposition of biological modalities. In this study we fill that gap by extending the cross-species two-pore physiologically-based pharmacokinetic (PBPK) platform with more detailed respiratory tract that includes the airways and alveolar space with epithelial lining fluid. We parameterize the paracellular and FcRn-facilitated exchange pathways between the epithelial lining fluid and lung interstitial space by building a mechanistic model for the exchange between the two. The optimized two-pore PBPK model described pulmonary exposure of several systemically dosed mAbs for which data is available and is also in agreement with the observed levels of endogenous IgG and albumin. The proposed framework can be used to assess pharmacokinetics of new lung-targeting biologic therapies and guide their dosing to achieve desired exposure at the pulmonary site-of-action.

Nebulized fusion inhibitory peptide protects cynomolgus macaques from measles virus infection

Measles is the most contagious airborne viral infection and the leading cause of child death among vaccine-preventable diseases. We show here that aerosolized lipopeptide fusion inhibitor, derived from heptad-repeat regions of the measles virus (MeV) fusion protein, blocks respiratory MeV infection in a non-human primate model, the cynomolgus macaque. We use a custom-designed mesh nebulizer to ensure efficient aerosol delivery of peptide to the respiratory tract and demonstrate the absence of adverse effects and lung pathology in macaques. The nebulized peptide efficiently prevents MeV infection, resulting in the complete absence of MeV RNA, MeV-infected cells, and MeV-specific humoral responses in treated animals. This strategy provides an additional means to fight against respiratory infection in non-vaccinated people, that can be readily translated to human trials. It presents a proof-of-concept for the aerosol delivery of fusion inhibitory peptides to protect against measles and other airborne viruses, including SARS-CoV-2, in case of high-risk exposure.

Identifiability of parameters in mathematical models of SARS-CoV-2 infections in humans

Determining accurate estimates for the characteristics of the severe acute respiratory syndrome coronavirus 2 in the upper and lower respiratory tracts, by fitting mathematical models to data, is made difficult by the lack of measurements early in the infection. To determine the sensitivity of the parameter estimates to the noise in the data, we developed a novel two-patch within-host mathematical model that considered the infection of both respiratory tracts and assumed that the viral load in the lower respiratory tract decays in a density dependent manner and investigated its ability to match population level data. We proposed several approaches that can improve practical identifiability of parameters, including an optimal experimental approach, and found that availability of viral data early in the infection is of essence for improving the accuracy of the estimates. Our findings can be useful for designing interventions.

Production of Inhalable Ultra-Small Particles for Delivery of Anti-Inflammation Medicine via a Table-Top Microdevice

A table-top microdevice was introduced in this work to produce ultrasmall particles for drug delivery via inhalation. The design and operation are similar to that of spray-drying equipment used in industry, but the device itself is much smaller and more portable in size, simpler to operate and more economical. More importantly, the device enables more accurate control over particle size. Using Flavopiridol, an anti-inflammation medication, formulations have been developed to produce inhalable particles for pulmonary delivery. A solution containing the desired components forms droplets by passing through an array of micro-apertures that vibrate via a piezo-electrical driver. High-purity nitrogen gas was introduced and flew through the designed path, which included the funnel collection and cyclone chamber, and finally was pumped away. The gas carried and dried the micronized liquid droplets along the pathway, leading to the precipitation of dry solid microparticles. The formation of the cyclone was essential to assure the sufficient travel path length of the liquid droplets to allow drying. Synthesis parameters were optimized to produce microparticles, whose morphology, size, physio-chemical properties, and release profiles met the criteria for inhalation. Bioactivity assays have revealed a high degree of anti-inflammation. The above-mentioned approach enabled the production of inhalable particles in research laboratories in general, using the simple table-top microdevice. The microparticles enable the inhalable delivery of anti-inflammation medicine to the lungs, thus providing treatment for diseases such as pulmonary fibrosis and COVID-19.

Nickel nanoparticles induce epithelial-mesenchymal transition in human bronchial epithelial cells via the HIF-1α/HDAC3 pathway

We and others have previously demonstrated that exposure to nickel nanoparticles (Nano-Ni) caused fibrogenic and carcinogenic effects; however, the underlying mechanisms are still not fully understood. This study aimed to investigate the effects of Nano-Ni on epithelial-mesenchymal transition (EMT) in human bronchial epithelial cells (BEAS-2B) and its underlying mechanisms since EMT is involved in both cancer pathogenesis and tissue fibrosis. Our results showed that exposure to Nano-Ni, compared to the control Nano-TiO2, caused a remarkable decrease in the expression of E-cadherin and an increase in the expression of vimentin and α-SMA, indicating an inducible role of Nano-Ni in EMT development in human bronchial epithelial cells. HIF-1α nuclear accumulation, HDAC3 upregulation, and decreased histone acetylation were also observed in the cells exposed to Nano-Ni, but not in those exposed to Nano-TiO2. Pretreatment of the cells with a specific HIF-1α inhibitor, CAY10585, or HIF-1α-specific siRNA transfection prior to Nano-Ni exposure resulted in the restoration of E-cadherin and abolished Nano-Ni-induced upregulation of vimentin and α-SMA, suggesting a crucial role of HIF-1α in Nano-Ni-induced EMT development. CAY10585 pretreatment also attenuated the HDAC3 upregulation and increased histone acetylation. Inhibition of HDAC3 with specific siRNA significantly restrained Nano-Ni-induced reduction in histone acetylation and restored EMT-related protein expression to near control levels. In summary, our findings suggest that exposure to Nano-Ni promotes the development of EMT in human bronchial epithelial cells by decreasing histone acetylation through HIF-1α-mediated HDAC3 upregulation. Our findings may provide information for further understanding of the molecular mechanisms of Nano-Ni-induced fibrosis and carcinogenesis.

Advanced Respiratory Models for Hazard Assessment of Nanomaterials—Performance of Mono-, Co- and Tricultures

Advanced in vitro models are needed to support next-generation risk assessment (NGRA), moving from hazard assessment based mainly on animal studies to the application of new alternative methods (NAMs). Advanced models must be tested for hazard assessment of nanomaterials (NMs). The aim of this study was to perform an interlaboratory trial across two laboratories to test the robustness of and optimize a 3D lung model of human epithelial A549 cells cultivated at the air–liquid interface (ALI). Potential change in sensitivity in hazard identification when adding complexity, going from monocultures to co- and tricultures, was tested by including human endothelial cells EA.hy926 and differentiated monocytes dTHP-1. All models were exposed to NM-300K in an aerosol exposure system (VITROCELL^® cloud-chamber). Cyto- and genotoxicity were measured by AlamarBlue and comet assay. Cellular uptake was investigated with transmission electron microscopy. The models were characterized by confocal microscopy and barrier function tested. We demonstrated that this advanced lung model is applicable for hazard assessment of NMs. The results point to a change in sensitivity of the model by adding complexity and to the importance of detailed protocols for robustness and reproducibility of advanced in vitro models.

Understanding the suitability of established antibiotics for oral inhalation from a pharmacokinetic perspective: an integrated model-based investigation based on rifampicin, ciprofloxacin and tigecycline in vivo data

BACKGROUND

Treating pulmonary infections by administering drugs via oral inhalation represents an attractive alternative to usual routes of administration. However, the local concentrations after inhalation are typically not known and the presumed benefits are derived from experiences with drugs specifically optimized for inhaled administration.

OBJECTIVES

A physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model was developed to elucidate the pulmonary PK for ciprofloxacin, rifampicin and tigecycline and link it to bacterial PK/PD models. An exemplary sensitivity analysis was performed to potentially guide drug optimization regarding local efficacy for inhaled antibiotics.

METHODS

Detailed pulmonary tissue, endothelial lining fluid and systemic in vivo drug concentration-time profiles were simultaneously measured for all drugs in rats after intravenous infusion. Using this data, a PBPK/PD model was developed, translated to humans and adapted for inhalation. Simulations were performed comparing potential benefits of oral inhalation for treating bronchial infections, covering intracellular pathogens and bacteria residing in the bronchial epithelial lining fluid.

RESULTS

The PBPK/PD model was able to describe pulmonary PK in rats. Often applied optimization parameters for orally inhaled drugs (e.g. high systemic clearance and low oral bioavailability) showed little influence on efficacy and instead mainly increased pulmonary selectivity. Instead, low permeability, a high epithelial efflux ratio and a pronounced post-antibiotic effect represented the most impactful parameters to suggest a benefit of inhalation over systemic administration for locally acting antibiotics.

CONCLUSIONS

The present work might help to develop antibiotics for oral inhalation providing high pulmonary concentrations and fast onset of exposure coupled with lower systemic drug concentrations.

Intersection of Inflammation and Senescence in the Aging Lung Stem Cell Niche

Aging is the final stage of development with stereotyped changes in tissue morphology. These age-related changes are risk factors for a multitude of chronic lung diseases, transcending the diverse pathogenic mechanisms that have been studied in disease-specific contexts. Two of the hallmarks of aging include inflammation and cellular senescence, which have been attributed as drivers of age-related organ decline. While these two age-related processes are often studied independently in the same tissue, there appears to be a reciprocal relationship between inflammation and senescence, which remodels the aging tissue architecture to increase susceptibility to chronic diseases. This review will attempt to address the “chicken or the egg” question as to whether senescence drives inflammation in the aging lung, or vice versa, and whether the causality of this relationship has therapeutic implications for age-related lung diseases.

Development of extra-fine particles containing nanosized meloxicam for deep pulmonary delivery: in vitro aerodynamic and cell line measurements

Pulmonary drug administration provides a platform for the effective local treatment of various respiratory diseases. Application of nano-sized active ingredients results in higher bioavailability because of their large specific surface area. Extra-fine dry powder inhalers reach the smaller airways, further improving therapeutic efficiency. Poorly water-soluble meloxicam was the selected active ingredient. We aimed to decrease the particle size into the nano range by wet milling and producing extra-fine inhalable particles via nano spray-drying. The diameter of the drug was reduced to 138 nm. The particle size of the dry products was between 1.1-1.5 µm, and the dispersed diameter was between 500-800 nm. Owing to the excipients (poly-vinyl-alcohol, leucine), the spray-dried particles presented nearly spherical morphology. The drug became partially amorphous. Thanks to the improved surface area, the solubility and the released and the diffused amount of the meloxicam increased in artificial lung media. The in vitro aerodynamic measurements showed that the leucine-containing formulations had outstanding fine particle fraction (FPF) deposition with 1.3 µm mass median aerodynamic diameter (MMAD). The aerodynamic particle counter test also proved the extra-fine aerodynamic particle size. The in vitro cell line experiments revealed the non-cytotoxicity of the products and the suppression of the interleukin concentration. Overall, the powders are suitable for deep pulmonary delivery and the local treatment of lung inflammations.

Advances in the design of new types of inhaled medicines

Inhalation of small molecule drugs has proven very efficacious for the treatment of respiratory diseases due to enhanced efficacy and a favourable therapeutic index compared with other dosing routes. It enables targeted delivery to the lung with rapid onset of therapeutic action, low systemic drug exposure, and thereby reduced systemic side effects. An increasing number of pharmaceutical companies and biotechs are investing in new modalities-for this review defined as therapeutic molecules with a molecular weight >800Da and therefore beyond usual inhaled small molecule drug-like space. However, our experience with inhaled administration of PROTACs, peptides, oligonucleotides (antisense oligonucleotides, siRNAs, miRs and antagomirs), diverse protein scaffolds, antibodies and antibody fragments is still limited. Investigating the retention and metabolism of these types of molecules in lung tissue and fluid will contribute to understanding which are best suited for inhalation. Nonetheless, the first such therapeutic molecules have already reached the clinic. This review will provide information on the physiology of healthy and diseased lungs and their capacity for drug metabolism. It will outline the stability, aggregation and immunogenicity aspects of new modalities, as well as recap on formulation and delivery aspects. It concludes by summarising clinical trial outcomes with inhaled new modalities based on information available at the end of 2021.

Nebulized fusion inhibitory peptide protects cynomolgus macaques from measles virus infection

Measles is the most contagious airborne viral infection and the leading cause of child death among vaccine-preventable diseases. We show here that aerosolized lipopeptide fusion inhibitors, derived from heptad-repeat regions of the measles virus (MeV) fusion protein, block respiratory MeV infection in a non-human primate model, the cynomolgus macaque. We used a custom-designed mesh nebulizer to ensure efficient aerosol delivery of peptides to the respiratory tract and demonstrated the absence of adverse effects and lung pathology in macaques. The nebulized peptide efficiently prevented MeV infection, resulting in the complete absence of MeV RNA, MeV-infected cells, and MeV-specific humoral responses in treated animals. This strategy provides an additional shield which complements vaccination to fight against respiratory infection, presenting a proof-of-concept for the aerosol delivery of fusion inhibitory peptides to protect against measles and other airborne viruses, including SARS-CoV-2, in case of high-risk exposure, that can be readily translated to human trials.

An Adverse Outcome Pathway for Decreased Lung Function Focusing on Mechanisms of Impaired Mucociliary Clearance Following Inhalation Exposure

Adverse outcome pathways (AOPs) help to organize available mechanistic information related to an adverse outcome into key events (KEs) spanning all organizational levels of a biological system(s). AOPs, therefore, aid in the biological understanding of a particular pathogenesis and also help with linking exposures to eventual toxic effects. In the regulatory context, knowledge of disease mechanisms can help design testing strategies using in vitro methods that can measure or predict KEs relevant to the biological effect of interest. The AOP described here evaluates the major processes known to be involved in regulating efficient mucociliary clearance (MCC) following exposures causing oxidative stress. MCC is a key aspect of the innate immune defense against airborne pathogens and inhaled chemicals and is governed by the concerted action of its functional components, the cilia and airway surface liquid (ASL). The AOP network described here consists of sequences of KEs that culminate in the modulation of ciliary beat frequency and ASL height as well as mucus viscosity and hence, impairment of MCC, which in turn leads to decreased lung function.

Absorption, distribution, metabolism, and excretion of methylene diphenyl diisocyanate and toluene diisocyanate: Many similarities and few differences

Methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) are high production volume chemicals used for the manufacture of polyurethanes. For both substances, the most relevant adverse health effects after overexposure in the workplace are isocyanate-induced asthma, lung function decrement and, to a much lesser extent, skin effects. Over the last two decades many articles have addressed the reactivity of MDI and TDI in biological media and the associated biochemistry, which increased the understanding of their biochemical and physiological behavior. In this review, these new insights with respect to similarities and differences concerning the adsorption, distribution, metabolism, and excretion (ADME) of these two diisocyanates and the implications on their toxicities are summarized. Both TDI and MDI show very similar behavior in reactivity to biological macromolecules, distribution, metabolism, and excretion. Evidence suggests that the isocyanate (NCO) group is scavenged at the portal-of-entry and is not systemically available in unbound reactive form. This explains the lack of other than portal-of-entry toxicity observed in repeated-dose inhalation tests.

Preparation and Characterization of Inhalable Ivermectin Powders as a Potential COVID-19 Therapy

Background: Ivermectin has received worldwide attention as a potential COVID-19 treatment after showing antiviral activity against SARS-CoV-2 in vitro. However, the pharmacokinetic limitations associated with oral administration have been postulated as limiting factors to its bioavailability and efficacy. These limitations can be overcome by targeted delivery to the lungs. In this study, inhalable dry powders of ivermectin and lactose crystals were prepared and characterized for the potential treatment of COVID-19. Methods: Ivermectin was co-spray dried with lactose monohydrate crystals and conditioned by storage at two different relative humidity points (43% and 58% RH) for a week. The in vitro dispersion performance of the stored powders was examined using a medium-high resistance Osmohaler connecting to a next-generation impactor at 60 L/min flow rate. The solid-state characteristics including particle size distribution and morphology, crystallinity, and moisture sorption profiles of raw and spray-dried ivermectin samples were assessed by laser diffraction, scanning electron microscopy, Raman spectroscopy, X-ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, and dynamic vapor sorption. Results: All the freshly spray-dried formulation (T0) and the conditioned samples could achieve the anticipated therapeutic dose with fine particle dose of 300 μg, FPF_recovered of 70%, and FPF_emitted of 83%. In addition, the formulations showed a similar volume median diameter of 4.3 μm and span of 1.9. The spray-dried formulations were stable even after conditioning and exposing to different RH points as ivermectin remained amorphous with predominantly crystalline lactose. Conclusion: An inhalable and stable dry powder of ivermectin and lactose crystals was successfully formulated. This powder inhaler ivermectin candidate therapy appears to be able to deliver doses that could be safe and effective to treat the SARS-COV-2 infection. Further development of this therapy is warranted.

Pulmonary Delivery of Aerosolized Chloroquine and Hydroxychloroquine to Treat COVID-19: In Vitro Experimentation to Human Dosing Predictions

In vitro screening for pharmacological activity of existing drugs showed chloroquine and hydroxychloroquine to be effective against severe acute respiratory syndrome coronavirus 2. Oral administration of these compounds to obtain desired pulmonary exposures resulted in dose-limiting systemic toxicity in humans. However, pulmonary drug delivery enables direct and rapid administration to obtain higher local tissue concentrations in target tissue. In this work, inhalable formulations for thermal aerosolization of chloroquine and hydroxychloroquine were developed, and their physicochemical properties were characterized. Thermal aerosolization of 40 mg/mL chloroquine and 100 mg/mL hydroxychloroquine formulations delivered respirable aerosol particle sizes with 0.15 and 0.33 mg per 55 mL puff, respectively. In vitro toxicity was evaluated by exposing primary human bronchial epithelial cells to aerosol generated from Vitrocell. An in vitro exposure to 7.24 μg of chloroquine or 7.99 μg hydroxychloroquine showed no significant changes in cilia beating, transepithelial electrical resistance, and cell viability. The pharmacokinetics of inhaled aerosols was predicted by developing a physiologically based pharmacokinetic model that included a detailed species-specific respiratory tract physiology and lysosomal trapping. Based on the model predictions, inhaling emitted doses comprising 1.5 mg of chloroquine or 3.3 mg hydroxychloroquine three times a day may yield therapeutically effective concentrations in the lung. Inhalation of higher doses further increased effective concentrations in the lung while maintaining lower systemic concentrations. Given the theoretically favorable risk/benefit ratio, the clinical significance for pulmonary delivery of aerosolized chloroquine and hydroxychloroquine to treat COVID-19 needs to be established in rigorous safety and efficacy studies.

Derivation of thresholds for inhaled chemically reactive irritants: Searching for substance-specific common denominators for read-across prediction

Emergency response planning guideline values are used to protect the public when there has been a short-term chemical release. These values serve the purpose of identifying areas where a hazard exists if the concentration of hazardous chemicals is exceeded for the specified exposure duration. This paper focuses on carbonyl chlorides, a class of highly irritant/corrosive chemical intermediates characterized by the reactive moiety R-COCl. Despite their unifying property of reacting with nucleophilic biopolymers/peptides lining the airways of the respiratory tract, their adverse outcome pathway (AOP), in addition to surface area dose, appears to be dominated by their site(s) of major deposition (liquid) or retention (gas) within the respiratory tract. Thus, the physicochemical properties "phase" and "lipophilicity" become more decisive for the AOP than the chemical structure. This complicates the grouping of portal-of-entry irritant chemicals for the read-across prediction of chemicals, especially those with semivolatile properties. Phosgene (COCl₂) served as a template to predict emergency response planning levels 2 (non-incapacitating, reversible injury) and 3 (nonlethal) for related chemicals such as SOCl₂, formates, and acid chlorides. A rationale and guide to the systematic characterization of uncertainties associated with the lung region, water solubility of the vapor phase, and chemical specificity is given. The approach described in this paper highlights the regional differences and outcomes that are phenotypically described as irritation of the respiratory tract. Especially for such a data-lean group of chemicals, reliable read-across predictions could reduce the uncertainty associated with the derivation of values used for emergency-related risk assessment and management. Likewise, the approach suggested could improve the grouping and categorization of such chemicals, providing a means to reduce animal testing with potentially corrosive chemicals. Overall, the course taken for read-across predictions provided valid estimates as long as emphasis was directed to the physicochemical properties determining the most critical regional injury within the respiratory tract.

In silico predictions of absorption of MDI substances after dermal or inhalation exposures to support a category based read-across assessment

Methylenediphenyl diisocyanate (MDI) substances used polyurethane production can range from their simplest monomeric forms (e.g., 4,4'-MDI) to mixtures of the monomers with various homologues, homopolymer, and prepolymer derivatives. The relative dermal or inhalation absorption of 39 constituents of these substances in human were predicted using the GastroPlus® program. Predicted dermal uptake and absorption of the three MDI monomers from an acetone vehicle was 84-86% and 1.4-1.5%, respectively, with lower uptake and absorption predicted for the higher MW analogs. Lower absorption was predicted from exposures in a more lipophilic vehicle (1-octanol). Modeled inhalation exposures afforded the highest pulmonary absorption for the MDI monomers (38-54%), with 3-27% for the MW range of 381-751, and <0.1% for the remaining, higher MW derivatives. Predicted oral absorption, representing mucociliary transport, ranged from 5 to 10% for the MDI monomers, 10-25% for constituents of MW 381-751, and ≤3% for constituents with MW > 900. These in silico evaluations should be useful in category-based, worst-case, Read-Across assessments for MDI monomers and modified MDI substances for potential systemic effects. Predictions of appreciable mucociliary transport may also be useful to address data gaps in oral toxicity testing for this category of compounds.

Immunotoxicity of nanomaterials in health and disease: Current challenges and emerging approaches for identifying immune modifiers in susceptible populations

Nanosafety assessment has experienced an intense era of research during the past decades driven by a vivid interest of regulators, industry, and society. Toxicological assays based on in vitro cellular models have undergone an evolution from experimentation using nanoparticulate systems on singular epithelial cell models to employing advanced complex models more realistically mimicking the respective body barriers for analyzing their capacity to alter the immune state of exposed individuals. During this phase, a number of lessons were learned. We have thus arrived at a state where the next chapters have to be opened, pursuing the following objectives: (1) to elucidate underlying mechanisms, (2) to address effects on vulnerable groups, (3) to test material mixtures, and (4) to use realistic doses on (5) sophisticated models. Moreover, data reproducibility has become a significant demand. In this context, we studied the emerging concept of adverse outcome pathways (AOPs) from the perspective of immune activation and modulation resulting in pro-inflammatory versus tolerogenic responses. When considering the interaction of nanomaterials with biological systems, protein corona formation represents the relevant molecular initiating event (e.g., by potential alterations of nanomaterial-adsorbed proteins). Using this as an example, we illustrate how integrated experimental-computational workflows combining in vitro assays with in silico models aid in data enrichment and upon comprehensive ontology-annotated (meta)data upload to online repositories assure FAIRness (Findability, Accessibility, Interoperability, Reusability). Such digital twinning may, in future, assist in early-stage decision-making during therapeutic development, and hence, promote safe-by-design innovation in nanomedicine. Moreover, it may, in combination with in silico-based exposure-relevant dose-finding, serve for risk monitoring in particularly loaded areas, for example, workplaces, taking into account pre-existing health conditions. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

TIPE polarity proteins are required for mucosal deployment of T lymphocytes and mucosal defense against bacterial infection

Mucosal surfaces are continuously exposed to, and challenged by, numerous commensal and pathogenic organisms. To guard against infections, a majority of the thymus-derived T lymphocytes are deployed at the mucosa. Although chemokines are known to be involved in the mucosal lymphocyte deployment, it is not clear whether lymphocytes enter the mucosa through directed migration or enhanced random migration. Here we report that TIPE (tumor necrosis factor-α-induced protein 8 (TNFAIP8)-like) proteins mediate directed migration of T lymphocytes into lung mucosa, and they are crucial for mucosal immune defense against Streptococcus pneumoniae infection. Knockout of both Tnfaip8 and Tipe2, which encode polarity proteins that control the directionality of lymphocyte migration, significantly reduced the numbers of T lymphocytes in the lung of mice. Compared with wild-type mice, Tnfaip8^−/−Tipe2^−/− mice also developed more severe infection with more pathogens entering blood circulation upon nasal Streptococcus pneumoniae challenge. Single-cell RNA-sequencing analysis revealed that TIPE proteins selectively affected mucosal homing of a unique subpopulation of T cells, called “T cells-2”, which expressed high levels of Ccr9, Tcf7, and Rag1/2 genes. TNFAIP8 and TIPE2 appeared to have overlapping functions since deficiency in both yielded the strongest phenotype. These data demonstrate that TIPE family of proteins are crucial for lung mucosal immunity. Strategies targeting TIPE proteins may help develop mucosal vaccines or treat inflammatory diseases of the lung.

Innate Receptors Expression by Lung Nociceptors: Impact on COVID-19 and Aging

The lungs are constantly exposed to non-sterile air which carries harmful threats, such as particles and pathogens. Nonetheless, this organ is equipped with fast and efficient mechanisms to eliminate these threats from the airways as well as prevent pathogen invasion. The respiratory tract is densely innervated by sensory neurons, also known as nociceptors, which are responsible for the detection of external stimuli and initiation of physiological and immunological responses. Furthermore, expression of functional innate receptors by nociceptors have been reported; however, the influence of these receptors to the lung function and local immune response is poorly described. The COVID-19 pandemic has shown the importance of coordinated and competent pulmonary immunity for the prevention of pathogen spread as well as prevention of excessive tissue injury. New findings suggest that lung nociceptors can be a target of SARS-CoV-2 infection; what remains unclear is whether innate receptor trigger sensory neuron activation during SARS-CoV-2 infection and what is the relevance for the outcomes. Moreover, elderly individuals often present with respiratory, neurological and immunological dysfunction. Whether aging in the context of sensory nerve function and innate receptors contributes to the disorders of these systems is currently unknown. Here we discuss the expression of innate receptors by nociceptors, particularly in the lungs, and the possible impact of their activation on pulmonary immunity. We then demonstrate recent evidence that suggests lung sensory neurons as reservoirs for SARS-CoV-2 and possible viral recognition via innate receptors. Lastly, we explore the mechanisms by which lung nociceptors might contribute to disturbance in respiratory and immunological responses during the aging process.