Characterization of biofilm formed by human-derived nanoparticles

Morphomolecular Characterization of Serum Nanovesicles From Microbiomes Differentiates Stable and Infarcted Atherosclerotic Patients

Microbial communities are considered decisive for maintaining a healthy situation or for determining diseases. Acute myocardial infarction (AMI) is an important complication of atherosclerosis caused by the rupture of atheroma plaques containing proinflammatory cytokines, reactive oxygen species, oxidized low-density lipoproteins (oxLDL), damaged proteins, lipids, and DNA, a microenvironment compatible with a pathogenic microbial community. Previously, we found that archaeal DNA-positive infectious microvesicles (iMVs) were detected in vulnerable plaques and in the sera of Chagas disease patients with heart failure. Now, we characterize and quantify the levels of serum microbiome extracellular vesicles through their size and content using morphomolecular techniques to differentiate clinical outcomes in coronary artery disease (CAD). We detected increased numbers of large iMVs (0.8–1.34 nm) with highly negative surface charge that were positive for archaeal DNA, Mycoplasma pneumoniae antigens and MMP9 in the sera of severe AMI patients, strongly favoring our hypothesis that pathogenic archaea may play a role in the worst outcomes of atherosclerosis. The highest numbers of EVs <100 nm (exosomes) and MVs from 100 to 200 nm in the stable atherosclerotic and control healthy groups compared with the AMI groups were indicative that these EVs are protective, entrapping and degrading infectious antigens and active MMP9 and protect against the development of plaque rupture.

Conclusion: A microbiome with pathogenic archaea is associated with high numbers of serum iMVs in AMI with the worst prognosis. This pioneering work demonstrates that the morphomolecular characterization and quantification of iEVs in serum may constitute a promising serum prognostic biomarker in CAD.

Induction of apoptosis and autophagy by calcifying nanoparticles in human bladder cancer cells

Calcifying nanoparticles have been linked to various types of human disease, but how they contribute to disease processes is unclear. Here, we examined whether and how calcifying nanoparticles isolated from patients with kidney stones are cytotoxic to human bladder cancer cells. Calcifying nanoparticles were isolated from midstream urine of patients with renal calcium oxalate stones and examined by electron microscopy. Human bladder cancer cells (EJ cells) were cultured in the presence of calcifying nanoparticles or nanohydroxyapatites for 12 and 72 h and examined for toxicity using the Cell Counting Kit-8, for autophagy using transmission electron microscopy and confocal microscopy, and for apoptosis using fluorescence microscopy, transmission electron microscopy, and flow cytometry. Changes in protein expression were analyzed by Western blotting. The results showed that the size and shape of the isolated calcifying nanoparticles were as expected. Calcifying nanoparticles were cytotoxic to EJ cells, more so than nanohydroxyapatites, and this was due, at least in part, to the production of intracellular reactive oxygen species. Transmission electron microscopy showed that calcifying nanoparticles were packaged into vesicles and autolysosomes. Calcifying nanoparticles induced greater autophagy and apoptosis than nanohydroxyapatites. Our findings demonstrate that calcifying nanoparticles can trigger bladder cancer cell injury by boosting reactive oxygen species production and stimulating autophagy and apoptosis.

Nanoparticle conversion to biofilms: in vitro demonstration using serum-derived mineralo-organic nanoparticles

AIMS

Mineralo-organic nanoparticles (NPs) detected in biological fluids have been described as precursors of physiological and pathological calcifications in the body. Our main objective was to examine the early stages of mineral NP formation in body fluids.

MATERIALS & METHODS

A nanomaterial approach based on atomic force microscopy, dynamic light scattering, electron microscopy and spectroscopy was used.

RESULTS

The mineral particles, which contain the serum proteins albumin and fetuin-A, initially precipitate in the form of round amorphous NPs that gradually grow in size, aggregate and coalesce to form crystalline mineral films similar to the structures observed in calcified human arteries.

CONCLUSION

Our study reveals the early stages of particle formation and provides a platform to analyze the role(s) of mineralo-organic NPs in human tissues.

Cytotoxicity induced by nanobacteria and nanohydroxyapatites in human choriocarcinoma cells

We explored the cytotoxic effects of nanobacteria (NB) and nanohydroxyapatites (nHAPs) against human choriocarcinoma cells (JAR) and the mechanisms of action underlying their cytotoxicity. JAR cells were co-cultured with NB and nHAPs for 48 h, and ultrastructural changes were more readily induced by NB than nHAPs. Autophagy in the plasma of JAR cells were observed in the NB group. The rate of apoptosis induced by NB was higher than that for nHAPs. The expression of Bax and FasR proteins in the NB group was stronger than that for the nHAP group. NB probably resulted in autophagic formation. Apoptosis was possibly activated via FasL binding to the FasR signaling pathway.

Of nanobacteria, nanoparticles, biofilms and their role in health and disease: facts, fancy and future

Nanobacteria have been at the center of a major scientific controversy in recent years owing to claims that they represent not only the smallest living microorganisms on earth but also new emerging pathogens associated with several human diseases. We and others have carefully examined these claims and concluded that nanobacteria are in fact nonliving mineralo-organic nanoparticles (NPs) that form spontaneously in body fluids. We have shown that these mineral particles possess intriguing biomimetic properties that include the formation of cell- and tissue-like morphologies and the possibility to grow, proliferate and propagate by subculture. Similar mineral NPs (bions) have now been found in both physiological and pathological calcification processes and they appear to represent precursors of physiological calcification cycles, which may at times go awry in disease conditions. Furthermore, by functioning at the nanoscale, these mineralo-organic NPs or bions may shed light on the fate of nanomaterials in the body, from both nanotoxicological and nanopathological perspectives.

Cytotoxicity and apoptosis induced by nanobacteria in human breast cancer cells

Background

The existing evidence that nanobacteria (NB) are closely associated with human disease is overwhelming. However, their potential toxicity against cancer cells has not yet been reported. The objective of this study was to investigate the cytotoxic effects of NB and nanohydroxyapatites (nHAPs) against human breast cancer cells and to elucidate the mechanisms of action underlying their cytotoxicity.

Methodology/principal findings

NB were isolated from calcified placental tissue, and nHAPs were artificially synthesized. The viability of the MDA-MB-231 human breast cancer cell line was tested by using the Kit-8 cell counting kit assay. Apoptosis was examined by transmission electron microscopy and flow cytometry. The endocytosis of NB and nHAPs by MDA-MB-231 cells was initially confirmed by microscopy. Although both NB and nHAPs significantly decreased MDA-MB-231 cell viability and increased the population of apoptotic cells, NB were more potent than nHAPs. After 72 hours, NB also caused ultrastructural changes typical of apoptosis, such as chromatin condensation, nuclear fragmentation, nuclear dissolution, mitochondrial swelling, and the formation of apoptotic bodies.

Conclusion/significance

In MDA-MB-231 human breast cancer cells, NB and nHAPs exerted cytotoxic effects that were associated with the induction of apoptosis. The effects exerted by NB were more potent than those induced by nHAPs. NB cytotoxicity probably emerged from toxic metabolites or protein components, rather than merely the hydroxyapatite shells. NB divided during culturing, and similar to cells undergoing binary fission, many NB particles were observed in culture by transmission electron microscopy, suggesting they are live microorganisms.

Surface charge controls the fate of Au nanorods in saline estuaries

This work reports the distribution of negatively charged, gold core nanoparticles in a model marine estuary as a function of time. A single dose of purified polystyrene sulfonate (PSS)-coated gold nanorods was added to a series of three replicate estuarine mesocosms to emulate an abrupt nanoparticle release event to a tidal creek of a Spartina -dominated estuary. The mesocosms contained several phases that were monitored: seawater, natural sediments, mature cordgrass, juvenile northern quahog clam, mud snails, and grass shrimp. Aqueous nanorod concentrations rose rapidly upon initial dosing and then fell to stable levels over the course of approximately 50 h, after which they remained stable for the remainder of the experiment (41 days total). The concentration of nanorods rose in all other phases during the initial phase of the experiment; however, some organisms demonstrated depuration over extended periods of time (100+ h) before removal from the dosed tanks. Clams and biofilm samples were also removed from the contaminated tanks post-exposure to monitor their depuration in pristine seawater. The highest net uptake of gold (mass normalized) occurred in the biofilm phase during the first 24 h, after which it was stable (to the 95% level of confidence) throughout the remainder of the exposure experiment. The results are compared against a previous study of positively charged nanoparticles of the same size to parameterize the role of surface charge in determining nanoparticle fate in complex aquatic environments.

Bions: a family of biomimetic mineralo-organic complexes derived from biological fluids

Mineralo-organic nanoparticles form spontaneously in human body fluids when the concentrations of calcium and phosphate ions exceed saturation. We have shown previously that these mineralo-organic nanoparticles possess biomimetic properties and can reproduce the whole phenomenology of the so-called nanobacteria-mineralized entities initially described as the smallest microorganisms on earth. Here, we examine the possibility that various charged elements and ions may form mineral nanoparticles with similar properties in biological fluids. Remarkably, all the elements tested, including sodium, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, copper, zinc, strontium, and barium form mineralo-organic particles with bacteria-like morphologies and other complex shapes following precipitation with phosphate in body fluids. Upon formation, these mineralo-organic particles, which we term bions, invariably accumulate carbonate apatite during incubation in biological fluids; yet, the particles also incorporate additional elements and thus reflect the ionic milieu in which they form. Bions initially harbor an amorphous mineral phase that gradually converts to crystals in culture. Our results show that serum produces a dual inhibition-seeding effect on bion formation. Using a comprehensive proteomic analysis, we identify a wide range of proteins that bind to these mineral particles during incubation in medium containing serum. The two main binding proteins identified, albumin and fetuin-A, act as both inhibitors and seeders of bions in culture. Notably, bions possess several biomimetic properties, including the possibility to increase in size and number and to be sub-cultured in fresh culture medium. Based on these results, we propose that bions represent biological, mineralo-organic particles that may form in the body under both physiological and pathological homeostasis conditions. These mineralo-organic particles may be part of a physiological cycle that regulates the function, transport and disposal of elements and minerals in the human body.

Microvesicles at the crossroads between infection and cardiovascular diseases

Observational and experimental studies continue to support the association of infection and infection-stimulated inflammation with development of cardiovascular disease (CVD) including atherosclerosis and thrombosis. Microvesicles (MV) are heterogeneous populations of sealed membrane-derived vesicles shed into circulation by activated mammalian cells and/or pathogenic microbes that may represent an interface between bacterial/microbial infection and increased risk of CVD. This review evaluates how MV act to modulate and intersect immunological and inflammatory responses to infection with particular attention to progression of CVD. Although infection-related stimuli provoke release of MV from blood and vascular cells, MV express phosphatidylserine and other procoagulant factors on their surface, which initiate and amplify blood coagulation. In addition, MV mediate cell-cell adhesion, which may stimulate production of pro-inflammatory cytokines in vascular cells, which in turn aggravate progression of CVD and propagate atherothrombosis. MV transfer membrane receptors, RNA and proteins among cells, and present auto-antigens from their cells of origin to proximal or remote target cells. Because MV harbor cell surface proteins and contain cytoplasmic components of the parent cell, they mediate biological messages and play a pivotal role in the crossroad between infection-stimulated inflammation and CVDs.

Serum-derived nanoparticles: de novo generation and growth in vitro, and internalization by mammalian cells in culture

AIM

While nanoparticles (NPs) have been shown to form spontaneously in body fluids such as serum, the possible implications of these NPs for cell cultures that use supporting media containing serum remain unclear. To understand the de novo formation of NPs, we delineated their growth characteristics, chemical composition and interaction with cells in culture.

MATERIALS & METHODS

Serum-derived particles were analyzed using a combination of dynamic light scattering, turbidity measurements, spectroscopic techniques and optical/electron microscopies.

RESULTS

NPs were found in serum and in serum-containing medium and they increased in size and number during incubation. The mineral particles, consisting mainly of calcium carbonate phosphate bound to organics such as proteins, underwent an amorphous-to-crystalline transformation with time. Serum-derived particles were internalized by the cells tested, eventually reaching lysosomal compartments.

CONCLUSION

The spontaneous formation of serum-derived NPs and their internalization by cells may have overlooked effects on cultured cells in vitro as well as potential pathophysiological consequences in vivo.

Key role of alkaline phosphatase in the development of human-derived nanoparticles in vitro

Alkaline phosphatase (ALP) is an enzyme critical for physiological and pathological biomineralization. Experiments were designed to determine whether ALP participates in the formation of calcifying nanometer sized particles (NPs) in vitro. Filtered homogenates of human calcified carotid artery, aorta and kidney stones were inoculated into cell culture medium containing 10% fetal bovine serum in the absence or presence of inhibitors of ALP or pyrophosphate. A calcific NP biofilm developed within 1 week after inoculation and their development was reduced by pyrophosphate and inhibitors of ALP. ALP protein and enzymatic activity were detected in washed NPs, whether calcified or decalcified. Therefore, ALP activity is required for the formation of calcifying NPs in vitro, as has previously been implicated during pathological calcification in vivo.

Proteomic evaluation of biological nanoparticles isolated from human kidney stones and calcified arteries

Calcifying biological nanoparticles (NPs) develop under cell culture conditions from homogenates of diverse tissue samples displaying extraosseous mineralization, including kidney stones and calcified aneurysms. Probes to definitively identify NPs in biological systems are lacking. Therefore, the aim of this study was to begin to establish a proteomic biosignature of NPs in order to facilitate more definitive investigation of their contribution to disease. Biological NPs derived from human kidney stones and calcified aneurysms were completely decalcified by overnight treatment with ethylenediaminetetraacetic acid or brief incubation in HCl, as evidenced by lack of a calcium shell and of Alizarin Red S staining, by transmission electron microscopy and confocal microscopy, respectively. Decalcified NPs contained numerous proteins, including some from bovine serum and others of prokaryotic origin. Most prominent of the latter group was EF-Tu, which appeared to be identical to EF-Tu from Staphylococcus epidermidis. A monoclonal antibody against human EF-Tu recognized a protein in Western blots of total NP lysate, as well as in intact NPs by immunofluorescence and immunogold EM. Approximately 8% of NPs were quantitatively recognized by the antibody using flow cytometry. Therefore, we have defined methods to reproducibly decalcify biological NPs, and identified key components of their proteome. These elements, including EF-Tu, can be used as biomarkers to further define the processes that mediate propagation of biological NPs and their contribution to disease.

Pathological calcification and replicating calcifying-nanoparticles: general approach and correlation

Calcification, a phenomenon often regarded by pathologists little more than evidence of cell death, is becoming recognized to be important in the dynamics of a variety of diseases from which millions of beings suffer in all ages. In calcification, all that is needed for crystal formation to start is nidi (nuclei) and an environment of available dissolved components at or near saturation concentrations, along with the absence of inhibitors for crystal formation. Calcifying nanoparticles (CNP) are the first calcium phosphate mineral containing particles isolated from human blood and were detected in numerous pathologic calcification related diseases. Controversy and critical role of CNP as nidi and triggering factor in human pathologic calcification are discussed.

Critical evaluation of gamma-irradiated serum used as feeder in the culture and demonstration of putative nanobacteria and calcifying nanoparticles

The culture and demonstration of putative nanobacteria (NB) and calcifying nanoparticles (CNP) from human and animal tissues has relied primarily on the use of a culture supplement consisting of FBS that had been γ-irradiated at a dose of 30 kGy (γ-FBS). The use of γ-FBS is based on the assumption that this sterilized fluid has been rid entirely of any residual NB/CNP, while it continues to promote the slow growth in culture of NB/CNP from human/animal tissues. We show here that γ-irradiation (5–50 kGy) produces extensive dose-dependent serum protein breakdown as demonstrated through UV and visible light spectrophotometry, fluorometry, Fourier-transformed infrared spectroscopy, and gel electrophoresis. Yet, both γ-FBS and γ-irradiated human serum (γ-HS) produce NB/CNP in cell culture conditions that are morphologically and chemically indistinguishable from their normal serum counterparts. Contrary to earlier claims, γ-FBS does not enhance the formation of NB/CNP from several human body fluids (saliva, urine, ascites, and synovial fluid) tested. In the presence of additional precipitating ions, both γ-irradiated serum (FBS and HS) and γ-irradiated proteins (albumin and fetuin-A) retain the inherent dual NB inhibitory and seeding capabilities seen also with their untreated counterparts. By gel electrophoresis, the particles formed from both γ-FBS and γ-HS are seen to have assimilated into their scaffold the same smeared protein profiles found in the γ-irradiated sera. However, their protein compositions as identified by proteomics are virtually identical to those seen with particles formed from untreated serum. Moreover, particles derived from human fluids and cultured in the presence of γ-FBS contain proteins derived from both γ-FBS and the human fluid under investigation—a confusing and unprecedented scenario indicating that these particles harbor proteins from both the host tissue and the FBS used as feeder. Thus, the NB/CNP described in the literature clearly bear hybrid protein compositions belonging to different species. We conclude that there is no basis to justify the use of γ-FBS as a feeder for the growth and demonstration of NB/CNP or any NB-like particles in culture. Moreover, our results call into question the validity of the entire body of literature accumulated to date on NB and CNP.