Combination effect of nanoparticles on the acute pulmonary inflammogenic potential: additive effect and antagonistic effect.

The combination effect of co-exposed different types of nanomaterials is little known although humans are generally exposed to a mixture of nanomaterials from urban ultrafine particles or industrial nanomaterials. Herein, we evaluated the combined effect of nanoparticles (NPs) using three types of NPs in different inflammogenic categories: carbon black (CB), nickel oxide (NiO), and copper oxide (CuO). A single type of NPs or NPs in combination was intratracheally instilled into the lungs of rats and the bronchoalveolar lavage fluid (BALF) was analyzed at 24 h after instillation to evaluate the acute inflammogenic potential. The percentage of neutrophils in BALF was selected as a toxicity endpoint and the potential for reactive oxygen species (ROS) generation, dose-response of the combined effect, sequential treatment of CB and NiO, and uptake of NiO to alveolar macrophages after combined treatment of CB and NiO were evaluated for the mechanism of the combined effect. Co-exposure of CuO and NiO showed an additive effect on the percentage of neutrophils and ROS generation potential, which implies that the physicochemical properties of each NP are not influenced by the other type. While CB exerted an antagonistic effect on the percentage of neutrophils in combined treatment with CuO or NiO. The antagonistic effect of CB was due to the scavenging activity of the ROS generated by the CuO and NiO rather than the competition in cellular uptake to target cells (i.e. alveolar macrophages), which highlight the importance of the combined effect of NPs in the risk assessment.

The early onset and persistent worsening pulmonary alveolar proteinosis in rats by indium oxide nanoparticles.

Workplace inhalation exposure to indium compounds has been reported to produce 'indium lung disease' characterized by pulmonary alveolar proteinosis (PAP), granulomas, and pulmonary fibrosis. However, there is little information about the pulmonary toxicity of nano-sized indium oxide (In2O3), which is widely used in various applications such as liquid crystal displays. In this study, we evaluated the time-course and dose-dependent lung injuries by In2O3 nanoparticles (NPs) after a single intratracheal instillation to rats. In2O3 NPs were instilled to female Wistar rats at 7.5, 30, and 90 cm2/rat and lung injuries were evaluated at day 1, 3, 7, 14, 30, 90, and 180 after a single intratracheal instillation. Treatment of In2O3 NPs induced worsening diverse pathological changes including PAP, persistent neutrophilic inflammation, type II cell hyperplasia, foamy macrophages, and granulomas in a time- and dose-dependent manner. PAP was induced from day 3 and worsened throughout the study. The concentrations of interleukin-1ß, tumor necrosis factor-α, and monocyte chemoattractant protein-1 in bronchoalveolar lavage fluid (BALF) showed dose- and time-dependent increases and the levels of these inflammatory mediators are consistent with the data of inflammatory cells in BALF and progressive lung damages by In2O3 NPs. This study suggests that a single inhalation exposure to In2O3 NPs can produce worsening lung damages such as PAP, chronic active inflammation, infiltration of foamy macrophages, and granulomas. The early onset and persistent PAP even at the very low dose (7.5 cm2/rat) implies that the re-evaluation of occupational recommended exposure limit for In2O3 NPs is urgently needed to protect workers.

Characteristics of single ocular motor nerve palsy associated with anti-GQ1b antibody.

To define the prevalence and characteristics of single ocular motor nerve palsy (OMNP) associated with positive serum anti-GQ1b antibody. We performed a prospective multicenter study that recruited 82 patients with single OMNP without identifiable causes from the history and neuroimaging in six neurology clinics of university hospitals. We measured serum anti-GQ1b antibody in all participants. Twelve patients with multiple OMNP and 30 with identifiable causes served as the controls. Overall, the prevalence of anti-GQ1b antibody syndrome was 10% (8/82) in patients with single OMNP and 6% (5/78) in those with single OMNP in isolation. None of the 14 patients with OMNP with identifiable causes showed positive serum anti-GQ1b antibody. The prevalence of anti-GQ1b antibody syndrome was much higher in patients with multiple OMNP than in those with single OMNP (50% vs. 10%, p < 0.01). Patients with single OMNP and positive anti-GQ1b antibody are younger (42 ± 16 vs. 58 ± 15, p < 0.05) and had a significantly higher frequency of preceding infection (75 vs. 19%, p < 0.05) and other neurological signs (38 vs. 1%, p < 0.05) than those with negative antibody. Eight patients with single OMNP and positive serum anti-GQ1b antibody involved the abducens (n = 6), trochlear (n = 1), or oculomotor nerve (n = 1). Single OMNP accompanying other neurological signs and multiple OMNP are more likely to be associated with anti-GQ1b antibody. Anti-GQ1b antibody syndrome should be considered even in patients with single OMNP, especially when antecedent infection was associated in younger patients.

Threshold Rigidity Values for the Asbestos-like Pathogenicity of High-Aspect-Ratio Carbon Nanotubes in a Mouse Pleural Inflammation Model.

The qualitative and quantitative evaluation of the physicochemical parameters associated with the pathogenicity of high-aspect-ratio nanomaterials is important for comprehensive regulation efforts and safety-by-design approaches. Here, we report quantitative data on the correlations between the rigidity of these nanomaterials and toxicity endpoints in vitro and in vivo. As measured by new ISO standards published in 2017, rigidity shows a strong positive correlation with inflammogenic potential, as indicated by inflammatory cell counts and IL-1ß (a biomarker for frustrated phagocytosis) levels in both the acute and chronic phases. In vitro experiments using differentiated THP-1 cells find that only highly rigid multiwalled carbon nanotubes (MWCNTs) and asbestos fibers lead to piercing and frustrated phagocytosis. Thus, this study suggests a bending ratio of 0.97 and a static bending persistence length of 1.08 as threshold rigidity values for asbestos-like pathogenicity. However, additional research using MWCNTs with rigidity values that lie between those of non-inflammogenic ( Db = 0.66 and SBPL = 0.87) and inflammogenic fibers ( Db = 0.97 and SBPL = 1.09) is required to identify more accurate threshold values, which would be useful for comprehensive regulation and safety-by-design approaches based on MWCNTs.

Persistent geotropic positional nystagmus in unilateral cerebellar lesions.

OBJECTIVE: To determine the prevalence of central lesions in persistent geotropic positional nystagmus, and characteristics and anatomical substrates of the nystagmus in cerebellar lesions. METHODS: We prospectively recruited 58 patients with persistent geotropic positional nystagmus at the Dizziness Clinic of Pusan National University Hospital. Seven patients with unilateral cerebellar lesions were subjected to analysis of clinical characteristics, oculographic data, and MRI lesions. For comparison, we studied 37 cases of peripheral persistent geotropic positional nystagmus. RESULTS: The prevalence of central lesions in persistent geotropic positional nystagmus was 12% (7/58). Persistent geotropic positional nystagmus in cerebellar lesions was mostly asymmetrical. Horizontal nystagmus changed in direction during the bow-and-lean test with null positions. All patients showed impaired horizontal smooth pursuit bilaterally, and 3 of them also had positional downbeat nystagmus. The peak intensity and asymmetry of persistent geotropic positional nystagmus did not differ between central and peripheral groups (p > 0.05), while there was a difference in the maxima. Lesion overlays revealed that damage to the cerebellar tonsil was responsible for the generation of persistent geotropic positional nystagmus. CONCLUSION: Although persistent geotropic positional nystagmus in cerebellar lesions shares the characteristics of nystagmus measures with peripheral cases, accompanying central oculomotor signs can aid in differentiation. In tonsillar lesions, compensatory rotational feedback due to erroneous estimation of the direction of gravity may generate constant horizontal geotropic positional nystagmus.

High inflammogenic potential of rare earth oxide nanoparticles: the New Hazardous Entity.

Due to the exponential increase in the development and utilization of rare earth oxide nanoparticles (REO NPs) in various fields, the possibility of exposure in humans by inhalation has increased. However, there are little information about hazards of REO NPs and its mechanisms of toxicity. In this study, we evaluated the acute pulmonary inflammation using 10 REO NPs (Dy2O3, Er2O3, Eu2O3, Gd2O3 La2O3, Nd2O3, Pr6O11, Sm2O3, Tb4O7, and Y2O3) and four well-known toxic particles (CuO, NiO, ZnO, and DQ12). Minimum three doses per NP were instilled into the lungs of female Wistar rats at surface area dose metric and lung inflammation was evaluated at 24 h post-instillation by bronchoalveolar lavage fluid (BALF) analysis and histopathological observation. All types of REO NPs showed common pathological changes including mild to moderate infiltration of neutrophils and activated macrophages in the alveoli, peribronchial, and perivascular region. The inflammogenic potential evaluated by the number of granulocytes divided by the treated surface area dose showed all types of REO NPs has much higher inflammogenic potential than DQ12, ZnO, and NiO NPs. The correlation plot between the number of granulocytes and the potential for reactive oxygen species (ROS) generation showed a good correlation with exception of Pr6O11. The higher inflammogenic potential of REO NPs than that of well-known highly toxic particles imply that REO NPs need special attention for inhalation exposure and more studies are needed. In addition, the potential of ROS generation is one of the key factors producing lung inflammation by REO NPs.

Differential Contribution of Constituent Metal Ions to the Cytotoxic Effects of Fast-Dissolving Metal-Oxide Nanoparticles.

The main mechanism of toxicity for fast-dissolving nanoparticles (NPs) is relatively simple as it originates from the intrinsic toxicity of their constituent elements rather than complicated surface reactivity. However, there is little information about the compared toxicity of fast-dissolving NP and its constituent ion, which is essential for understanding the mechanism of NP toxicity and the development of a structure-toxicity relationship (STR) model. Herein, we selected three types of fast-dissolving metal-oxide NPs (CoO, CuO, and ZnO) and constituent metal chlorides (CoCl2, CuCl2, and ZnCl2) to compare dose-response curves between NP and its constituent metal. These materials were treated relevant cell lines for inhalation setting (i.e., differentiated THP-1 cells for macrophages and A549 cells for alveolar epithelial cells) and cytotoxicity as an endpoint was evaluated at 24 h post-incubation. The results showed that CoO and CuO NPs in both cell types showed similar patterns of dose-response curves and cytotoxic potential compared to that of their respective metal chloride. On the other hand, ZnO NPs in both cell types showed a completely different dose-response curve compared to that of ZnCl2: ZnO NPs showed modest slope and much less potential for cytotoxicity compared to that of ZnCl2. These results imply that fast-dissolving metal-oxide NPs are not always have similar dose-response curves and toxic potentials compared to their constituent metal chlorides and this may be due to the differential mechanism of intracellular uptake of these substances and their interaction with intracellular detoxification molecules. Further investigations are needed for the use of toxic potential of metal ions as a predicting factors of fast-dissolving NPs toxicity. In addition, chelating agent specific for dissolved metal ions can be applied for the treatment of these fast-dissolving NPs.

Evaluation of the dose metric for acute lung inflammogenicity of fast-dissolving metal oxide nanoparticles.

Although surface area metric was suggested as an appropriate dose metric for acute lung inflammation of NPs, it might not be effective for fast-dissolving NPs because they lose their reactive surface when dissolved in the phagolysosomes. Herein, we evaluated the dose metric for fast-dissolving NPs using a rat intratracheal instillation model. A panel of fast-dissolving NPs (CoO, CuO and ZnO) and their constituent metal ions (CoCl2, CuCl2 and ZnCl2) were compiled and each compound was intratracheally instilled into the lungs of female Wistar rats at the same molar concentrations in the NP doses (40, 100 and 400 µg/rat). The toxicity endpoints including cytological and biochemical data in bronchoalveolar lavage fluid were evaluated at 24 h after instillation. To evaluate the dose metric, each toxicity endpoint was plotted against the instilled dose (mass or surface area) or the equivalent dose (mass or surface area) that was weighted by the ratio of specific dose-generated responses between metal chlorides. Dose-response curves of fast-dissolving NPs about percentage of granulocytes, lactate dehydrogenase levels and total protein levels showed similar pattern but slightly less potential than those of their respective metal chlorides. When each toxicity endpoint was plotted against the equivalent mass dose, three types of NPs showed more overlapping dose-response curves than other dose metrics. In conclusion, this study implies that the equivalent mass dose is an appropriate dose metric for fast-dissolving NPs and the main factor determining the slope of the dose-response curve is the intrinsic toxicity of the their constituent ions.

Nickel oxide nanoparticles can recruit eosinophils in the lungs of rats by the direct release of intracellular eotaxin.

BACKGROUND: Instillation of highly soluble nanoparticles (NPs) into the lungs of rodents can cause acute eosinophilia without any previous sensitizations by the role of dissolved ions. However, whether gradually dissolving NPs can cause the same type of eosinophilia remains to be elucidated. We selected nickel oxide (NiO) as a gradually dissolving NP and evaluated the time course pulmonary inflammation pattern as well as its mechanisms. METHODS: NiO NPs were intratracheally instilled into female Wistar rats at various concentrations (50, 100, and 200 cm(2)/rat) and the lung inflammation was evaluated at various time-points (1, 2, 3, and 4 days). As positive controls, NiCl2 and the ovalbumin-induced allergic airway inflammation model was applied. NiCl2 was instilled at 171.1 µg Ni/rat, which is equivalent nickel concentration of 200 cm(2)/rat of NiO NPs. Cytological analysis and biochemical analysis including lactate dehydrogenase (LDH), total protein, and pro-inflammatory cytokines were measured in bronchoalveolar lavage fluid (BALF). The levels of total immunoglobulin E (IgE) and anaphylatoxins (C3a and C5a) were measured in BALF and serum. The levels of eotaxin were measured in the alveolar macrophages and normal lung tissue before and after addition of cell lysis buffer to evaluate whether the direct lysis of cells can release intracellular eotaxin. RESULTS: NiO NPs produced acute neutrophilic inflammation throughout the study. However, eosinophils were recruited at 3 and 4 days post-instillation of NiO NPs and the magnitude and pattern of inflammation was similar with NiCl2 at 24 h post-instillation. The eosinophil recruitment by NiO NPs was not related with either the levels of total IgE or anaphylatoxins. The lysis of alveolar macrophages and normal lung tissue showed high levels of intracellular eotaxin and the levels of LDH showed positive correlation with the levels of eotaxin. CONCLUSIONS: Instillation of NiO NPs produced neutrophilia at 1 and 2 days after instillation, while the mixed type of neutrophilic and eosinophilic inflammation was produced at 3 and 4 days post-instillation, which was consistent with NiCl2. The mechanism of the eosinophilia involves the direct release of intracellular eotaxin due to the rupture of cells by the accumulated solubilized nickel ions in the phagolysosome.