Nanoparticle decoration impacts airborne fungal pathobiology

Mechanisms of Antifungal Properties of Metal Nanoparticles

The appearance of resistant species of fungi to the existent antimycotics is challenging for the scientific community. One emergent technology is the application of nanotechnology to develop novel antifungal agents. Metal nanoparticles (NPs) have shown promising results as an alternative to classical antimycotics. This review summarizes and discusses the antifungal mechanisms of metal NPs, including combinations with other antimycotics, covering the period from 2005 to 2022. These mechanisms include but are not limited to the generation of toxic oxygen species and their cellular target, the effect of the cell wall damage and the hyphae and spores, and the mechanisms of defense implied by the fungal cell. Lastly, a description of the impact of NPs on the transcriptomic and proteomic profiles is discussed.

Emerging nanotechnologies for targeting antimicrobial resistance

Antimicrobial resistance is a leading cause of mortality worldwide. Without newly approved antibiotics and antifungals being brought to the market, resistance is being developed to the ones currently available to clinicians. The reason is the applied evolutionary pressure to bacterial and fungal species due to the wide overuse of common antibiotics and antifungals in clinical practice and agriculture. Biofilms harbour antimicrobial-resistant subpopulations, which make their antimicrobial treatment even more challenging. Nanoparticle-based technologies have recently been shown to successfully overcome antimicrobial resistance in both planktonic and biofilms phenotypes. This results from the combination of novel nanomaterial research and classic antimicrobial therapies which promise to deliver a whole new generation of high-performance active nanocarrier systems. This review discusses the latest developments of promising nanotechnologies with applications against resistant pathogens and evaluates their potential and feasibility for use in novel antimicrobial therapies.

Nanomaterials in the environment, human exposure pathway, and health effects: A review

Nanomaterials (NMs), both natural and synthetic, are produced, transformed, and exported into our environment daily. Natural NMs annual flux to the environment is around 97% of the total and is significantly higher than synthetic NMs. However, synthetic NMs are considered to have a detrimental effect on the environment. The extensive usage of synthetic NMs in different fields, including chemical, engineering, electronics, and medicine, makes them susceptible to be discharged into the atmosphere, various water sources, soil, and landfill waste. As ever-larger quantities of NMs end up in our environment and start interacting with the biota, it is crucial to understand their behavior under various environmental conditions, their exposure pathway, and their health effects on human beings. This review paper comprises a large portion of the latest research on NMs and the environment. The article describes the natural and synthetic NMs, covering both incidental and engineered NMs and their behavior in the natural environment. The review includes a brief discussion on sampling strategies and various analytical tools to study NMs in complex environmental matrices. The interaction of NMs in natural environments and their pathway to human exposure has been summarized. The potential of NMs to impact human health has been elaborated. The nanotoxicological effect of NMs based on their inherent properties concerning to human health is also reviewed. The knowledge gaps and future research needs on NMs are reported. The findings in this paper will be a resource for researchers working on NMs all over the world to understand better the challenges associated with NMs in the natural environment and their human health effects.

Boosting nanotoxicity to combat multidrug-resistant bacteria in pathophysiological environments

Nanomaterials are promising novel antibiotics, but often ineffective. We found that nanomaterial-bacteria complex formation occurred with various nanomaterials. The bactericidal activity of NMs strongly depends on their physical binding to (multidrug-resistant) bacteria. Nanomaterials' binding and antibiotic effect was reduced by various pathophysiological biomolecule coronas strongly inhibiting their antibiotic effects. We show from analytical to in vitro to in vivo that nanomaterial-based killing could be restored by acidic pH treatments. Here, complex formation of negatively-charged, plasma corona-covered, nanomaterials with bacteria was electrostatically enhanced by reducing bacteria's negative surface charge. Employing in vivo skin infection models, acidic pH-induced complex formation was critical to counteract Staphylococcus aureus infections by silver nanomaterials. We explain why nano-antibiotics show reduced activity and provide a clinically practical solution.

Mechanisms of nanotoxicity - biomolecule coronas protect pathological fungi against nanoparticle-based eradication

Whereas nanotoxicity is intensely studied in mammalian systems, our knowledge of desired or unwanted nano-based effects for microbes is still limited. Fungal infections are global socio-economic health and agricultural problems, and current chemical antifungals may induce adverse side-effects in humans and ecosystems. Thus, nanoparticles are discussed as potential novel and sustainable antifungals via the desired nanotoxicity but often fail in practical applications. In our study, we found that nanoparticles' toxicity strongly depends on their binding to fungal spores, including the clinically relevant pathogen Aspergillus fumigatus as well as common plant pests, such as Botrytis cinerea or Penicillum expansum. Employing a selection of the model and antimicrobial nanoparticles, we found that nanoparticle-spore complex formation is influenced by the NM's physicochemical properties, such as size, identified as a key determinant for our silica model particles. Biomolecule coronas acquired in pathophysiologically and ecologically relevant environments, protected fungi against nanoparticle-induced toxicity as shown by employing antimicrobial ZnO, Ag, or CuO nanoparticles as well as dissolution-resistant quantum dots. Mechanistically, dose-dependent corona-mediated resistance was conferred via reducing the physical adsorption of nanoparticles to fungi. The inhibitory effect of biomolecules on nano-based toxicity of Ag NPs was further verified in vivo, using the invertebrate Galleria mellonella as an alternative non-mammalian infection model. We provide the first evidence that biomolecule coronas are not only relevant in mammalian systems but also for nanomaterial designs as future antifungals for human health, biotechnology, and agriculture.

Investigating the Vascular Toxicity Outcomes of the Irreversible Proteasome Inhibitor Carfilzomib

Background: Carfilzomib’s (Cfz) adverse events in myeloma patients include cardiovascular toxicity. Since carfilzomib’s vascular effects are elusive, we investigated the vascular outcomes of carfilzomib and metformin (Met) coadministration. Methods: Mice received: (i) saline; (ii) Cfz; (iii) Met; (iv) Cfz+Met for two consecutive (acute) or six alternate days (subacute protocol). Leucocyte-derived reactive oxygen species (ROS) and serum NO_x levels were determined and aortas underwent vascular and molecular analyses. Mechanistic experiments were recapitulated in aged mice who received similar treatment to young animals. Primary murine (prmVSMCs) and aged human aortic smooth muscle cells (HAoSMCs) underwent Cfz, Met and Cfz+Met treatment and viability, metabolic flux and p53-LC3-B expression were measured. Experiments were recapitulated in AngII, CoCl₂ and high-glucose stimulated HAoSMCs. Results: Acutely, carfilzomib alone led to vascular hypo-contraction and increased ROS release. Subacutely, carfilzomib increased ROS release without vascular manifestations. Cfz+Met increased PGF2α-vasoconstriction and LC3-B-dependent autophagy in both young and aged mice. In vitro, Cfz+Met led to cytotoxicity and autophagy, while Met and Cfz+Met shifted cellular metabolism. Conclusion: Carfilzomib induces a transient vascular impairment and oxidative burst. Cfz+Met increased vascular contractility and synergistically induced autophagy in all settings. Therefore, carfilzomib cannot be accredited for a permanent vascular dysfunction, while Cfz+Met exert vasoprotective potency.

Drag forces on nanoparticles in the free-molecule regime: Effect of the particle temperature

In the present paper, we theoretically study the drag force on nanoparticles in the free-molecule regime. It has been widely assumed that the particle temperature is equal to the gas media temperature in the open literature. However, this assumption can be invalid in some real applications. Based on the kinetic theory, we obtain the generalized formulas for the drag force on nanoparticles in the free-molecule regime. It is found that there exists a significant error induced by the assumption of equal temperature between the particle and the surrounding gas. Therefore, it is necessary to consider the effect of the particle temperature in the analysis of the particle transport properties.

Aspergillus fumigatus and Aspergillosis in 2019

Aspergillus fumigatus is a saprotrophic fungus; its primary habitat is the soil. In its ecological niche, the fungus has learned how to adapt and proliferate in hostile environments. This capacity has helped the fungus to resist and survive against human host defenses and, further, to be responsible for one of the most devastating lung infections in terms of morbidity and mortality. In this review, we will provide (i) a description of the biological cycle of A. fumigatus; (ii) a historical perspective of the spectrum of aspergillus disease and the current epidemiological status of these infections; (iii) an analysis of the modes of immune response against Aspergillus in immunocompetent and immunocompromised patients; (iv) an understanding of the pathways responsible for fungal virulence and their host molecular targets, with a specific focus on the cell wall; (v) the current status of the diagnosis of different clinical syndromes; and (vi) an overview of the available antifungal armamentarium and the therapeutic strategies in the clinical context. In addition, the emergence of new concepts, such as nutritional immunity and the integration and rewiring of multiple fungal metabolic activities occurring during lung invasion, has helped us to redefine the opportunistic pathogenesis of A. fumigatus.

Hide and Seek: Nanomaterial Interactions With the Immune System

Engineered nanomaterials hold promise for a wide range of applications in medicine. However, safe use of nanomaterials requires that interactions with biological systems, not least with the immune system, are understood. Do nanomaterials elicit novel or unexpected effects, or is it possible to predict immune responses to nanomaterials based on how the immune system handles pathogens? How does the bio-corona of adsorbed biomolecules influence subsequent immune interactions of nanomaterials? How does the grafting of polymers such as poly(ethylene glycol) onto nanomaterial surfaces impact on these interactions? Can ancient immune evasion or “stealth” strategies of pathogens inform the design of nanomaterials for biomedical applications? Can nanoparticles co-opt immune cells to target diseased tissues? The answers to these questions may prove useful for the development of nanomedicines.

Resistance to Nano-Based Antifungals Is Mediated by Biomolecule Coronas

Fungal infections are a growing global health and agricultural threat, and current chemical antifungals may induce various side-effects. Thus, nanoparticles are investigated as potential novel antifungals. We report that nanoparticles' antifungal activity strongly depends on their binding to fungal spores, focusing on the clinically important fungal pathogen Aspergillus fumigatus as well as common plant pathogens, such as Botrytis cinerea. We show that nanoparticle-spore complex formation was enhanced by the small nanoparticle size rather than the material, shape or charge, and could not be prevented by steric surface modifications. Fungal resistance to metal-based nanoparticles, such as ZnO-, Ag-, or CuO-nanoparticles as well as dissolution-resistant quantum dots, was mediated by biomolecule coronas acquired in pathophysiological and ecological environments, including the lung surfactant, plasma or complex organic matters. Mechanistically, dose-dependent corona-mediated resistance occurred via reducing physical adsorption of nanoparticles to fungal spores. The inhibitory effect of biomolecules on the antifungal activity of Ag-nanoparticles was further verified in vivo, using the invertebrate Galleria mellonella as an A. fumigatus infection model. Our results explain why current nanoantifungals often show low activity in realistic application environments, and will guide nanomaterial designs that maximize functionality and safe translatability as potent antifungals for human health, biotechnology, and agriculture.

The Human In Vivo Biomolecule Corona onto PEGylated Liposomes: A Proof-of-Concept Clinical Study

The self-assembled layered adsorption of proteins onto nanoparticle (NP) surfaces, once in contact with biological fluids, is termed the "protein corona" and it is gradually seen as a determinant factor for the overall biological behavior of NPs. Here, the previously unreported in vivo protein corona formed in human systemic circulation is described. The human-derived protein corona formed onto PEGylated doxorubicin-encapsulated liposomes (Caelyx) is thoroughly characterized following the recovery of liposomes from the blood circulation of ovarian carcinoma patients. In agreement with previous investigations in mice, the in vivo corona is found to be molecularly richer in comparison to its counterpart ex vivo corona. The intravenously infused liposomes are able to scavenge the blood pool and surface-capture low-molecular-weight, low-abundance plasma proteins that cannot be detected by conventional plasma proteomic analysis. This study describes the previously elusive or postulated formation of protein corona around nanoparticles in vivo in humans and illustrates that it can potentially be used as a novel tool to analyze the blood circulation proteome.

Biomolecule-corona formation confers resistance of bacteria to nanoparticle-induced killing: Implications for the design of improved nanoantibiotics

Multidrug-resistant bacterial infections are a global health threat. Nanoparticles are thus investigated as novel antibacterial agents for clinical practice, including wound dressings and implants. We report that nanoparticles' bactericidal activity strongly depends on their physical binding to pathogens, including multidrug-resistant primary clinical isolates, such as Staphylococcus aureus, Klebsiella pneumoniae or Enterococcus faecalis. Using controllable nanoparticle models, we found that nanoparticle-pathogen complex formation was enhanced by small nanoparticle size rather than material or charge, and was prevented by 'stealth' modifications. Nanoparticles seem to preferentially bind to Gram-positive pathogens, such as Listeria monocytogenes, S. aureus or Streptococcus pyrogenes, correlating with enhanced antibacterial activity. Bacterial resistance to metal-based nanoparticles was mediated by biomolecule coronas acquired in pathophysiological environments, such as wounds, the lung, or the blood system. Biomolecule corona formation reduced nanoparticles' binding to pathogens, but did not impact nanoparticle dissolution. Our results provide a mechanistic explanation why nano-sized antibiotics may show reduced activity in clinically relevant environments, and may inspire future nanoantibiotic designs with improved and potentially pathogen-specific activity.