Engineered aluminum nanoparticle induces mitochondrial deformation and is predicated on cell phenotype

Widespread Myalgia and Chronic Fatigue: Phagocytes from Macrophagic Myofasciitis Patients Exposed to Aluminum Oxyhydroxide-Adjuvanted Vaccine Exhibit Specific Inflammatory, Autophagic, and Mitochondrial Responses

(1) Background: Macrophagic myofasciitis (MMF) is an inflammatory histopathological lesion demonstrating long-term biopersistence of vaccine-derived aluminum adjuvants within muscular phagocytic cells. Affected patients suffer from widespread myalgia and severe fatigue consistent with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a poorly understood disorder suspected to result from chronic immune stimulation by infectious and inorganic particles. (2) Methods: In this study we determined the immuno-metabolic properties of MMF phagocytic cells compared to controls, at rest and upon exposure to aluminum oxyhydroxide adjuvant, with or without adsorbed antigens, using protein quantification and an oxygen consumption assay. (3) Results: MMF and control cells similarly internalized the adjuvant and vaccine but MMF cells specifically expressed Rubicon and Nox2, two molecules unique to the LC3-associated phagocytosis (LAP) machinery, a non-canonical autophagic pathway able to downregulate canonical autophagy. MMF cells exhibited an altered inflammatory secretome, producing more pain-inducing CXC chemokines and less TNF-α than controls, consistent with chronic myalgia and exhaustion of the immune system previously documented in ME/CFS. MMF cells exhibited mitochondrial metabolism dysfunction, with exacerbated reaction to adjuvanted vaccine, contrasting with limited spare respiratory capacity and marked proton leak weakening energy production. (4) Conclusions: MMF phagocytes seemingly use LAP to handle aluminum oxyhydroxide vaccine particles, secrete pain-inducing molecules, and exhibit exacerbated metabolic reaction to the vaccine with limited capacity to respond to ongoing energetic requests.

Mitophagy and its regulatory mechanisms in the biological effects of nanomaterials

Mitophagy is a selective cellular process critical for the removal of damaged mitochondria. It is essential in regulating mitochondrial number, ensuring mitochondrial functionality, and maintaining cellular equilibrium, ultimately influencing cell destiny. Numerous pathologies, such as neurodegenerative diseases, cardiovascular disorders, cancers, and various other conditions, are associated with mitochondrial dysfunctions. Thus, a detailed exploration of the regulatory mechanisms of mitophagy is pivotal for enhancing our understanding and for the discovery of novel preventive and therapeutic options for these diseases. Nanomaterials have become integral in biomedicine and various other sectors, offering advanced solutions for medical uses including biological imaging, drug delivery, and disease diagnostics and therapy. Mitophagy is vital in managing the cellular effects elicited by nanomaterials. This review provides a comprehensive analysis of the molecular mechanisms underpinning mitophagy, underscoring its significant influence on the biological responses of cells to nanomaterials. Nanoparticles can initiate mitophagy via various pathways, among which the PINK1-Parkin pathway is critical for cellular defense against nanomaterial-induced damage by promoting mitophagy. The role of mitophagy in biological effects was induced by nanomaterials, which are associated with alterations in Ca2+ levels, the production of reactive oxygen species, endoplasmic reticulum stress, and lysosomal damage.

Toxicity mechanism of engineered nanomaterials: Focus on mitochondria

With the rapid development of nanotechnology, engineered nanomaterials (ENMs) are widely used in various fields. This has exacerbated the environmental pollution and human exposure of ENMs. The study of toxicity of ENMs and its mechanism has become a hot research topic in recent years. Mitochondrial damage plays an important role in the toxicity of ENMs. This paper reviews the structural damage, dysfunction, and molecular level perturbations caused by different ENMs to mitochondria, including ZnO NPs, Ag NPs, TiO2 NPs, iron oxide NPs, cadmium-based quantum dots, CuO NPs, silica NPs, carbon-based nanomaterials. Among them, mitochondrial quality control plays an important role in mitochondrial damage. We further summarize the cellular level outcomes caused by mitochondrial damage, mainly including, apoptosis, ferroptosis, pyroptosis and inflammation response. In addition, we concluded that reducing mitochondrial damage at source as well as accelerating recovery from mitochondrial damage through ENMs modification and pharmacological intervention are two feasible strategies. This review further provides new insights into the mitochondrial toxicity mechanisms of ENMs and provides a new foothold for predicting human health and environmental risks of ENMs.

DMSA-coated IONPs trigger oxidative stress, mitochondrial metabolic reprograming and changes in mitochondrial disposition, hindering cell cycle progression of cancer cells

There is increasing interest in modulating the redox homeostasis of tumors since high levels of reactive oxygen species (ROS) make them more vulnerable to changes in these species. Nanomedicine offers promise in this context as such applications may provoke biological responses that induce ROS production. Indeed, iron oxide nanoparticles (IONPs) can induce ROS accumulation through the so-called Fenton reaction of iron, further augmenting the ROS in tumors and overloading the antioxidant system beyond its capacity, thereby driving oxidative stress to a level that is incompatible with cell survival. Here, three different coatings for IONPs were compared to assess their intrinsic capacity to induce ROS production in cells. Of these coatings, dimercaptosuccinic acid-coated IONPs (DMSA-NPs) provoked the strongest ROS production, which was associated with the ability to reprogram the metabolism of cancer cells. This latter phenomenon involved shutting-down oxidative phosphorylation (OXPHOS), shifting mitochondrial morphology towards a more elongated phenotype, reducing the total mitochondrial mass and ultimately, blocking cell proliferation by inducing G0/G1 cell cycle arrest. Consequently, the data obtained highlights the importance of studying the chemical properties of IONPs, presenting DMSA-NPs as a novel tool to induce oxidative stress in cancer cells and alter their cell fate.

A preparation of bacterial outer membrane with osmium tetroxide and uranyl acetate co-stain enables improved structural determination by transmission electron microscopy

Biological nanoparticles, such as bacterial outer membrane vesicles (OMVs), are routinely characterized through transmission electron microscopy (TEM). In this study, we report a novel method to prepare OMVs for TEM imaging. To preserve vesicular shape and structure, we developed a dual fixation protocol involving osmium tetroxide incubation prior to negative staining with uranyl acetate. Combining osmium tetroxide with uranyl acetate resulted in preservation of sub-50 nm vesicles and improved morphological stability, enhancing characterization of lipid-based nanoparticles by TEM.

Toll-like receptor 4 is a key regulator of asthma exacerbation caused by aluminum oxide nanoparticles via regulation of NF-κB phosphorylation

Aluminum oxide nanoparticles (Al₂O₃ NPs) have recently been reported to cause an inflammatory response in the lungs, and studies are being conducted on their adverse effects, especially in patients with underlying lung diseases such as asthma. However, the underlying mechanism of asthma aggravation caused by Al₂O₃ NPs remains unclear. This study investigated whether Al₂O₃ NPs exacerbate ovalbumin (OVA)-induced asthma and focused on the correlation between toll-like receptor 4 (TLR4) signaling and Al₂O₃ NP-induced asthma exacerbation. Al₂O₃ NP exposure in asthmatic mice resulted in increased inflammatory cell counts in the lungs, airway hyperresponsiveness, and increased levels of inflammatory cytokines compared with only OVA-induced mice, and excessive secretion of mucus was observed in the airways. Moreover, Al₂O₃ NP exposure in OVA-induced mice increased the expression levels of TLR4, phospho-nuclear transcription factor-kappa B (p-NFκB), myeloid differentiation factor 88 (MyD88), and phospho-NF kappa B inhibitor alpha (p-IκBα). Furthermore, in the lungs of TLR4 knockout mice exposed to Al₂O₃ NPs and in a human airway epithelial cell line with down regulated TLR4, the expression levels of MyD88, p-NFκB, and p-IκBα were decreased, and asthma-related allergic responses were reduced. Therefore, we demonstrated that TLR4 is important for aggravation of asthma induced by Al₂O₃ NPs, and this study provides useful information regarding as yet undiscovered novel target signaling.

Subcellular-Level Mitochondrial Energy Metabolism Response in the Fat Body of the German Cockroach Fed Abamectin

Mitochondria are the leading organelle for energy metabolism. The toxic effects of environmental toxicants on mitochondrial morphology, energy metabolism, and their determination of cell fate have already been broadly studied. However, minimal research exists on effects of environmental toxicants such as pesticides on mitochondrial energy metabolism at in vitro subcellular level, particularly from an omics perspectives (e.g., metabolomics). Here, German cockroach (Blattella germanica) was fed diets with (0.01 and 0.001 mg/mL) and without abamectin, and highly purified fat body mitochondria were isolated. Swelling measurement confirmed abnormal mitochondrial swelling caused by abamectin stress. The activity of two key mitochondrial energy metabolism-related enzymes, namely succinic dehydrogenase and isocitrate dehydrogenase, was significantly affected. The metabolomic responses of the isolated mitochondria to abamectin were analyzed via untargeted liquid chromatography/mass spectrometry metabolomics technology. Fifty-two differential metabolites (DMs) were identified in the mitochondria between the 0.001 mg/mL abamectin-fed and the control groups. Many of these DMs were significantly enriched in pathways involved in ATP production and energy consumption (e.g., oxidative phosphorylation, TCA cycle, and pentose phosphate pathway). Nineteen of the DMs were typically related to energy metabolism. This study is valuable for further understanding mitochondrial toxicology under environmental toxicants, particularly its subcellular level.