Toxicokinetic assessment of inhalatory absorption of Diisobutyl phthalate (DiBP) using a novel thermal desorption-GC-MS method to determine phthalate diesters in blood plasma

Phthalates are endocrine disrupting compounds that have been found in outdoor and indoor air. However, little is known about their inhalatory absorption. Although measurement of urinary metabolites is the current standard, complex and convergent metabolism of phthalates poses the necessity for alternative methodologies such as the quantitation of parental compounds in plasma. We determined the inhalatory absorption of Diisobutyl phthalate (DiBP) using a novel method based on a thermal desorption probe (TSP)-gas chromatography-mass spectrometry developed for the detection and quantitation of nine phthalate diesters in blood plasma, which fulfilled the acceptance criteria suggested by FDA guidelines regarding specificity, matrix effect, recovery, linearity, sensitivity, accuracy, and precision. After inhalation, plasma concentration of DiBP exhibited two peaks, suggesting a first, rapid absorption event, followed by a second, delayed one and a first order elimination stage. Half-life was calculated as 62 min and bioavailability, compared to IV route, was 15%.

Inflammatory response in human alveolar epithelial cells after TiO2 NPs or ZnO NPs exposure: Inhibition of surfactant protein A expression as an indicator for loss of lung function

The increasing use of metal oxide nanoparticles (MONPs) as TiO₂ NPs or ZnO NPs has led to environmental release and human exposure. The respiratory system, effects on lamellar bodies and surfactant protein A (SP-A) of pneumocytes, can be importantly affected. Exposure of human alveolar epithelial cells (A549) induced differential responses; a higher persistence of TiO₂ in cell surface and uptake (measured by Atomic Force Microscopy) and sustained inflammatory response (by means of TNF-α, IL-10, and IL-6 release) and ROS generation were observed, whereas ZnO showed a modest response and low numbers in cell surface. A reduction in SP-A levels at 24 h of exposure to TiO₂ NPs (concentration-dependent) or ZnO NPs (the higher concentration) was also observed, reversed by blocking the inflammatory response (by the inhibition of IL-6). Loss of SP-A represents a relevant target of MONPs-induced inflammatory response that could contribute to cellular damage and loss of lung function.

In vitro cytotoxicity study of superparamagnetic iron oxide and silica nanoparticles on pneumocyte organelles

Inhalation is the main route of nanoparticles (NP) exposure during manufacturing. Although many mechanisms of toxicity have been described, the interaction of NP with relevant pneumocytes organelles is not widely understood. Considering that the physicochemical properties of NP influence their toxicological responses, the objective of this study was to evaluate whether exposure to different NP, crystalline Fe₃O₄ NP and amorphous SiO₂ NP could alter pneumocytes organelles in alveolar epithelial cells. To achieve this goal, cell viability, ultrastructural changes, lysosomal damage, mitochondrial membrane potential (MMP), lipid droplets (LD) formation and cytokines production were evaluated by MTT, electron microscopy, lysotracker red staining, JC-1, Oil Red staining and Milliplex® assay respectively. Both NP were observed within lamellar bodies (LB), lysosomes, and cytoplasm causing morphological changes. Exposure to SiO₂ NP at 6 h induced lysosomal activation, but not Fe₃O₄ NP. MMP decreased and LD increased at the highest concentrations after both NP exposure. Pro-inflammatory cytokines were released only after SiO₂ NP exposure at 48 h. These results indicate that SiO₂ NP have a greater impact than Fe₃O₄ NP on organelles responsible for energy, secretion, degradation and metabolism in pneumocytes leading to the development of respiratory disorders or the exacerbation of preexisting conditions. Therefore, the established biocompatibility for amorphous NP has to be reconsidered.

Plasma protein adsorption on Fe3O4-PEG nanoparticles activates the complement system and induces an inflammatory response

BACKGROUND

Understanding of iron oxide nanoparticles (IONP) interaction with the body milieu is crucial to guarantee their efficiency and biocompatibility in nanomedicine. Polymer coating to IONP, with polyethyleneglycol (PEG) and polyvinylpyrrolidone (PVP), is an accepted strategy to prevent toxicity and excessive protein binding.

AIM

The aim of this study was to investigate the feature of IONP adsorption of complement proteins, their activation and consequent inflammatory response as a strategy to further elucidate their biocompatibility.

METHODS

Three types of IONP with different surface characteristics were used: bare (IONP-bare), coated with PVP (IONP-PVP) and PEG-coated (IONP-PEG). IONPs were incubated with human plasma and adsorbed proteins were identified. BALB/c mice were intravenously exposed to IONP to evaluate complement activation and proinflammatory response.

RESULTS

Protein corona fingerprinting showed that PEG surface around IONP promoted a selective adsorption of complement recognition molecules which would be responsible for the complement system activation. Furthermore, IONP-PEG activated in vitro, the complement system and induced a substantial increment of C3a and C4a anaphylatoxins while IONP-bare and IONP-PVP did not. In vivo IONP-PEG induced an increment in complement activation markers (C5a and C5b-9), and proinflammatory cytokines (IL-1β, IL-6, TNF-α).

CONCLUSION

The engineering of nanoparticles must incorporate the association between complement proteins and nanomedicines, which will regulate the immunostimulatory effects through a selective adsorption of plasma proteins and will enable a safer application of IONP in human therapy.

Exposure to ambient particulate matter induces oxidative stress in lung and aorta in a size- and time-dependent manner in rats

Exposure to particulate matter (PM) has been implicated in oxidative stress (OxS) and inflammation as underlying mechanisms of lung damage and cardiovascular alterations. PM is a chemical mixture that can be subdivided according to their aerodynamic size into coarse (CP), fine (FP), and ultrafine (UFP) particulates. We investigated, in a rat model, the induction of OxS (protein oxidation and antioxidant response), carcinogen-DNA adduct formation, and inflammatory mediators in lung in response to different airborne particulate fractions, CP, FP, and UFP, after an acute and subchronic exposure. In addition, OxS was evaluated in the aorta to assess the effects beyond the lungs. Exposure to CP, FP, and UFP induced time- and size-dependent lung protein oxidation and DNA adduct formation. After acute and subchronic exposure, nuclear factor erythroid-2 (Nrf2) activation was observed in the lung, by electrophoretic mobility shift assay, and the induction of mRNA antioxidant enzymes in the FP and UFP groups, but not in the CP. Cytokine concentration of interleukin 1β, interleukin 6, and macrophage inflammatory protein-2 was significantly increased in bronchoalveolar lavage fluid after acute exposure to FP and UFP. Activation of Nrf2 and expression of mRNA antioxidant enzymes were observed only after the subchronic exposure to FP and UFP in the aorta. Our results indicate that FP and UFP were mainly accountable for the oxidant toxic effects in the lung; OxS is spread from the lung to the cardiovascular system. We conclude that the biological mechanisms associated with transient OxS and inflammation are particle size and time-dependent exposure resulting in acute lung injury, which later reaches the vascular system.

Bismuth subsalicylate nanoparticles with anaerobic antibacterial activity for dental applications

In recent years, nanomaterials have been used in the medical-dental field as new alternative antimicrobial agents. Bismuth subsalicylate (BSS) has been used as an antimicrobial agent, but the effect of BSS in the form of nanoparticles (BSS-nano) as a potential antimicrobial agent has not been tested, in specific against bacteria responsible for periodontal disease. The aim of this study was to evaluate the antibacterial effect of BSS-nano against oral anaerobic bacteria and to assess the safety of BSS-nano by evaluating their cytotoxicity in human gingival fibroblast (HGF-1) cells. BSS-nano were synthesized by laser ablation and were previously physico-chemically characterized using in vitro assays. The antibacterial activity was measured using the tetrazolium-based XTT assay, and cytotoxicity was determined using lactate dehydrogenase (LDH) and MTS assays in HGF-1 cells. Transmission electron microscopy of HGF-1 exposed to BSS-nano was also performed. BSS-nano was shown to have a primary size of 4-22 nm and a polygonal shape. Among the tested bacterial strains, those with a greater sensitivity to BSS-nano (highest concentration of 21.7 μg ml^-1) were A. actinomycetemcomitans, C. gingivalis, and P. gingivalis. BSS-nano at a concentration of 60 μg ml^-1 showed low cytotoxicity (6%) in HFG-1 cells and was mainly localized intracellularly in acidic vesicles. Our results indicate that the concentration of BSS-nano used as an effective antibacterial agent does not induce cytotoxicity in mammalian cells; thus, BSS-nano can be applied as an antibacterial agent in dental materials or antiseptic solutions.

A comparison of the human and mouse protein corona profiles of functionalized SiO2 nanocarriers

Nanoparticles are a promising cancer therapy for their use as drug carriers given their versatile functionalization with polyethylene glycol and proteins that can be recognized by overexpressed receptors in tumor cells. However, it has been suggested that in biological fluids, proteins cover nanoparticles, which gives the proteins a biological identity that could be responsible for unexpected biological responses: the so-called protein corona. A relevant biological event that is usually ignored in protein-corona formation is the interspecies differences in protein binding, which can be involved in the discrepancies observed in preclinical studies and the nanoparticle safety and efficiency. Hence, the aim of this study was to determine the differences between human and mouse plasma protein corona profiles in an active therapy model using silicon dioxide nanoparticles (SiO₂ nanoparticles) functionalized with polyethylene glycol and transferrin. Functionalized SiO₂ nanoparticles were made with a primary particle size of 25 nm and a transferrin content of 50 μg mg^-1 of nanoparticles and were PEGylated with a cross-linker. The proteomic analysis by nanoliquid chromatography tandem-mass spectrometry (nanoLC-MS/MS) showed interspecies differences. The most abundant proteins found in the human protein corona profile were immunoglobulins, actin cytoplasmic 1, hemoglobin subunit beta, serotransferrin, ficolin-3, complement C3, and apolipoprotein A-1. Meanwhile, the mouse protein corona adsorbed the serine protease inhibitor A3K, serotransferrin, alpha-1-antitrypsin 1-2, hemoglobin subunit beta, and fibrinogen gamma and beta chains. These protein-corona profile differences in the functionalized SiO₂ nanoparticles indicate that biological responses observed in in vivo models could not be translated to clinical use and must be considered in the interpretation of preclinical trials in order to design more efficient and safer nanomedicines.

Early kidney damage induced by subchronic exposure to PM2.5 in rats

BACKGROUND

Particulate matter exposure is associated with respiratory and cardiovascular system dysfunction. Recently, we demonstrated that fine particles, also named PM_2.5, modify the expression of some components of the angiotensin and bradykinin systems, which are involved in lung, cardiac and renal regulation. The endocrine kidney function is associated with the regulation of angiotensin and bradykinin, and it can suffer damage even as a consequence of minor alterations of these systems. We hypothesized that exposure to PM_2.5 can contribute to early kidney damage as a consequence of an angiotensin/bradykinin system imbalance, oxidative stress and/or inflammation.

RESULTS

After acute and subchronic exposure to PM_2.5, lung damage was confirmed by increased bronchoalveolar lavage fluid (BALF) differential cell counts and a decrease of surfactant protein-A levels. We observed a statistically significant increment in median blood pressure, urine volume and water consumption after PM_2.5 exposure. Moreover, increases in the levels of early kidney damage markers were observed after subchronic PM_2.5 exposure: the most sensitive markers, β-2-microglobulin and cystatin-C, increased during the first, second, sixth and eighth weeks of exposure. In addition, a reduction in the levels of specific cytokines (IL-1β, IL-6, TNF-α, IL-4, IL-10, INF-γ, IL-17a, MIP-2 and RANTES), and up-regulated angiotensin and bradykinin system markers and indicators of a depleted antioxidant response, were also observed. All of these effects are in concurrence with the presence of renal histological lesions and an early pro-fibrotic state.

CONCLUSION

Subchronic exposure to PM_2.5 induced an early kidney damage response that involved the angiotensin/bradykinin systems as well as antioxidant and immune imbalance. Our study demonstrates that PM_2.5 can induce a systemic imbalance that not only affects the cardiovascular system, but also affects the kidney, which may also overall contribute to PM-related diseases.

Protein corona acts as a protective shield against Fe3O4-PEG inflammation and ROS-induced toxicity in human macrophages

Protein corona (PC) is the main biological entity of initial cell interaction and can define the toxicological response to Fe3O4 nanoparticles (IONP). Polymer coating to IONP, polyethilenglycol (PEG) and polyvinylpyrrolidone (PVP), is a widely accepted strategy to prevent toxicity and avoid excessive protein binding. The aim of this study was to assess the role of PC as a potential protector for ROS-induced cytotoxicity and pro-inflammatory response in THP-1 macrophages (exposed to three different IONP: bare, PVP or PEG coated). Cells were exposed to either IONP in RPMI-1640 media or IONP with a preformed human PC. All three IONP showed cytotoxic effects, which in the presence of PC was abolished. IONP-PEG exposure significantly increased ROS, mitochondrial dysfunction and pro-inflammatory cytokines release (IL-1β and TNF-α). PC presence on IONP-PEG promoted a decrease in ROS and prevented cytokine secretion. Also, presence of PC reduced cell uptake for IONP-bare, but had no influence on IONP-PVP or IONP-PEG. Hence, the reduction in IONP-PEG cytotoxicity can be attributed to PC shielding against ROS generation and pro-inflammatory response and not a differential uptake in THP-1 macrophages. The presence of the PC as a structural element of NP biological entity provides in vivo-relevant conditions for nanosafety testing.

Chemical characterization of extractable water soluble matter associated with PM10 from Mexico City during 2000

We report the chemical composition of PM10-associated water-soluble species in Mexico City during the second semester of 2000. PM10 samples were collected at four ambient air quality monitoring sites in Mexico City. We determined soluble ions (chloride, nitrate, sulfate, ammonium, sodium, potassium), ionizable transition metals (Zn, Fe, Ti, Pb, Mn, V, Ni, Cr, Cu) and soluble protein. The higher PM(10) levels were observed in Xalostoc (45-174 microg m(-3)) and the lowest in Pedregal (19-54 microg m(-3)). The highest SO2 average concentrations were observed in Tlalnepantla, NO2 in Merced and O3 and NO(x) in Pedregal. The concentration range of soluble sulfate was 6.7-7.9 and 19-25.5 microg m(-3) for ammonium, and 14.8-29.19 for soluble V and 3.2-7.7 ng m(-3) for Ni, suggesting a higher contribution of combustion sources. PM-associated soluble protein levels varied between 0.038 and 0.169 mg m(-3), representing a readily inhalable constituent that could contribute to adverse outcomes. The higher levels for most parameters studied were observed during the cold dry season, particularly in December. A richer content of soluble metals was observed when they were expressed by mass/mass units rather than by air volume units. Significant correlations between Ni-V, Ni-SO4(-2), V-SO4(-2), V-SO2, Ni-SO2 suggest the same type of emission source. The variable soluble metal and ion concentrations were strongly influenced by the seasonal meteoclimatic conditions and the differential contribution of emission sources. Our data support the idea that PM10 mass concentration by itself does not provide a clear understanding of a local PM air pollution problem.

Hematotoxicity response in rats by the novel copper-based anticancer agent: casiopeina II

The in vivo toxicity of the novel copper-based anticancer agent, casiopeina II (Cu(4,7-dimethyl-1,10-phenanthroline)(glycine)NO3) (CII), was investigated. Casiopeinas are a family of copper-coordinated complexes that have shown promising anticancer activity. The major toxic effect attributed to a single i.v. administration of CII (5 mg/kg dose) in the rat was an hemolytic anemia (reduced hemoglobin concentration (HB), red blood cell (RBC) count and packed cell volume (PCV) accompanied by a marked neutrophilic leukocytosis) 12 h and 5 days after administration, attributed to a direct erythrocyte damage. Increased reticulocyte levels and presence of normoblasts in peripheral blood 5 days post-administration indicated an effective erythropoietic response with recovery at 15 days. Increase in spleen weight and the morphological evidence of congestion of the red pulp (RP) with erythrocytes (E) resulting in a higher ratio of red to white pulp (WP) was consistent with increased uptake of damaged erythrocytes by the reticuloendothelial system observed by histopathology and electron microscopy. Extramedullary hemopoiesis was markedly increased at 5 days giving further evidence of a regenerative erythropoietic response that had an effective recovery by 15 days. Morphological changes in spleen cellularity were consistent with hematotoxicity, mainly a reduction of the red pulp/white pulp ratio, increase in erythrocyte content at 12 h, and an infiltration of nucleated cells in the red pulp at 5 days, with a tendency towards recovery 15 days after administration. The erythrocyte damage is attributed to generation of free radicals and oxidative damage on the membrane and within cells resulting from the reduction of Cu(II) and the probable dissociation of the CII complex.

Induction of apoptosis by a novel copper-based anticancer compound, casiopeina II, in L1210 murine leukaemia and CH1 human ovarian carcinoma cells

The activity of casiopeina II [Cu(1,4-dimethyl-1, 10-phenanthroline)(glycine)NO(3)], a novel anticancer agent, was tested in two cell lines, L1210 murine leukaemia, CH1 human ovarian carcinoma, cisplatin-resistant and sensitive. Exposure of the cells to a range of concentrations of casiopeina II indicates that this copper complex kills cells by apoptosis and necrosis. Condensed chromatin and nuclear fragmentation were observed after exposure to casiopeina II. The caspase inhibitor Z-Val-Ala-DL-Asp-fluoromethylketone (Z-VAD-FMK) almost completely inhibited apoptosis induced by cisplatin; however, casiopeina II-induced apoptosis was inhibited only by 50-70%. These data are consistent with caspase activation (measured by Z-Asp-Glu-Val-Asp-7-amino-4-trifluoromethylcoumarin; Z-DEVD-AFC) by casiopeina II and cisplatin and confirm that caspases are activated in the apoptotic cell death induced by casiopeina II. DNA fragmentation was observed in L1210 cells, but not in CH1 cells. No difference in susceptibility to induction of apoptosis by casiopeina II was found between sensitive and cisplatin resistant cells. In this work we show that the novel copper-based antineoplastic agent casiopeina II is highly active against murine and human cancer cell lines, including cell lines resistant to cisplatin.