Nano(bio)Materials Do Not Affect Macrophage Phenotype-A Study Conducted by the REFINE Project

Macrophages are well known for their involvement in the biocompatibility, as well as biodistribution, of nano(bio)materials. Although there are a number of rodent cell lines, they may not fully recapitulate primary cell responses, particularly those of human cells. Isolation of tissue-resident macrophages from humans is difficult and may result in insufficient cells with which to determine the possible interaction with nano(bio)materials. Isolation of primary human monocytes and differentiation to monocyte-derived macrophages may provide a useful tool with which to further study these interactions. To that end, we developed a standard operating procedure for this differentiation, as part of the Regulatory Science Framework for Nano(bio)material-based Medical Products and Devices (REFINE) project, and used it to measure the secretion of bioactive molecules from M1 and M2 differentiated monocytes in response to model nano(bio)materials, following an initial assessment of pyrogenic contamination, which may confound potential observations. The SOP was deployed in two partner institutions with broadly similar results. The work presented here shows the utility of this assay but highlights the relevance of donor variability in responses to nano(bio)materials. Whilst donor variability can provide some logistical challenges to the application of such assays, this variability is much closer to the heterogeneous cells that are present in vivo, compared to homogeneous non-human cell lines.

Transferability and reproducibility of exposed air-liquid interface co-culture lung models

BACKGROUND

The establishment of reliable and robust in vitro models for hazard assessment, a prerequisite for moving away from animal testing, requires the evaluation of model transferability and reproducibility. Lung models that can be exposed via the air, by means of an air-liquid interface (ALI) are promising in vitro models for evaluating the safety of nanomaterials (NMs) after inhalation exposure. We performed an inter-laboratory comparison study to evaluate the transferability and reproducibility of a lung model consisting of the human bronchial cell line Calu-3 as a monoculture and, to increase the physiologic relevance of the model, also as a co-culture with macrophages (either derived from the THP-1 monocyte cell line or from human blood monocytes). The lung model was exposed to NMs using the VITROCELL® Cloud12 system at physiologically relevant dose levels.

RESULTS

Overall, the results of the 7 participating laboratories are quite similar. After exposing Calu-3 alone and Calu-3 co-cultures with macrophages, no effects of lipopolysaccharide (LPS), quartz (DQ12) or titanium dioxide (TiO2) NM-105 particles on the cell viability and barrier integrity were detected. LPS exposure induced moderate cytokine release in the Calu-3 monoculture, albeit not statistically significant in most labs. In the co-culture models, most laboratories showed that LPS can significantly induce cytokine release (IL-6, IL-8 and TNF-α). The exposure to quartz and TiO2 particles did not induce a statistically significant increase in cytokine release in both cell models probably due to our relatively low deposited doses, which were inspired by in vivo dose levels. The intra- and inter-laboratory comparison study indicated acceptable interlaboratory variation for cell viability/toxicity (WST-1, LDH) and transepithelial electrical resistance, and relatively high inter-laboratory variation for cytokine production.

CONCLUSION

The transferability and reproducibility of a lung co-culture model and its exposure to aerosolized particles at the ALI were evaluated and recommendations were provided for performing inter-laboratory comparison studies. Although the results are promising, optimizations of the lung model (including more sensitive read-outs) and/or selection of higher deposited doses are needed to enhance its predictive value before it may be taken further towards a possible OECD guideline.

Application of KU812 cells for assessing complement activation related effects by nano(bio)materials

Immunocompatibility issues related to nano(bio)materials, particularly liposomal formulations, involving activation of the complement system have been relatively well described however, they highlight the importance of preclinical evaluation of such interactions. These complement-mediated hypersensitivity reactions, in which basophils are implicated, are associated with complement activation-related pseudoallergy (CARPA). Ex vivo investigation of such events using primary basophils is technically challenging due to the relatively limited number of circulating basophils in peripheral blood. In the current work, the KU812 cell line has been applied as an in vitro model for basophil activation to investigate CARPA-related responses following exposure to test materials obtained from the REFINE consortium. To that end, we developed a standard operating procedure measuring a panel of cell-surface markers indicative of basophilic activation. Two laboratories performed the assays, demonstrating a clear difference in responses between liposomal and polymeric nano(bio)materials, while interlaboratory comparison of the standard operating procedure demonstrated reproducibility in results, between the two facilities. These results suggest the potential to use this protocol as a screening method for such responses however, validation using primary basophils is now warranted.

Standardization of an in vitro assay matrix to assess cytotoxicity of organic nanocarriers: a pilot interlaboratory comparison

Nanotechnologies such as nanoparticles are established components of new medical devices and pharmaceuticals. The use and distribution of these materials increases the requirement for standardized evaluation of possible adverse effects, starting with a general cytotoxicity screening. The Horizon 2020 project "Regulatory Science Framework for Nano(bio)material-based Medical Products and Devices (REFINE)" identified in vitro cytotoxicity quantification as a central task and first step for risk assessment and development for medical nanocarriers. We have performed an interlaboratory comparison on a cell-assay matrix including a kinetic lactate dehydrogenase (LDH) release cell death and WST-8 cell viability assay adapted for testing organic nanocarriers in four well-characterized cell lines of different organ origins. Identical experiments were performed by three laboratories, namely the Biomedical Technology Center (BMTZ) of the University of Münster, SINTEF Materials and Chemistry (SINTEF), and the National Institute for Public Health and the Environment (RIVM) of the Netherlands according to new standard operating procedures (SOPs). The experiments confirmed that LipImage™ 815 lipidots^® are non-cytotoxic up to a concentration of 128 µg/mL and poly(alkyl cyanoacrylate) (PACA) nanoparticles for drug delivery of cytostatic agents caused dose-dependent cytotoxic effects on the cell lines starting from 8 µg/mL. PACA nanoparticles loaded with the active pharmaceutical ingredient (API) cabazitaxel showed a less pronounced dose-dependent effect with the lowest concentration of 2 µg/mL causing cytotoxic effects. The mean within laboratory standard deviation was 4.9% for the WST-8 cell viability assay and 4.0% for the LDH release cell death assay, while the between laboratory standard deviation was 7.3% and 7.8% for the two assays, respectively. Here, we demonstrated the suitability and reproducibility of a cytotoxicity matrix consisting of two endpoints performed with four cell lines across three partner laboratories. The experimental procedures described here can facilitate a robust cytotoxicity screening for the development of organic nanomaterials used in medicine.

Pathways Related to NLRP3 Inflammasome Activation Induced by Gold Nanorods

The widespread and increasing use of engineered nanomaterials (ENM) increases the risk of human exposure, generating concern that ENM may provoke adverse health effects. In this respect, their physicochemical characteristics are critical. The immune system may respond to ENM through inflammatory reactions. The NLRP3 inflammasome responds to a wide range of ENM, and its activation is associated with various inflammatory diseases. Recently, anisotropic ENM have become of increasing interest, but knowledge of their effects on the immune system is still limited. The objective of the study was to compare the effects of gold ENM of different shapes on NLRP3 inflammasome activation and related signalling pathways. Differentiated THP-1 cells (wildtype, ASC- or NLRP3-deficient), were exposed to PEGylated gold nanorods, nanostars, and nanospheres, and, thus, also different surface chemistries, to assess NLRP3 inflammasome activation. Next, the exposed cells were subjected to gene expression analysis. Nanorods, but not nanostars or nanospheres, showed NLRP3 inflammasome activation. ASC- or NLRP3-deficient cells did not show this effect. Gene Set Enrichment Analysis revealed that gold nanorod-induced NLRP3 inflammasome activation was accompanied by downregulated sterol/cholesterol biosynthesis, oxidative phosphorylation, and purinergic receptor signalling. At the level of individual genes, downregulation of Paraoxonase-2, a protein that controls oxidative stress, was most notable. In conclusion, the shape and surface chemistry of gold nanoparticles determine NLRP3 inflammasome activation. Future studies should include particle uptake and intracellular localization.

An Air-liquid Interface Bronchial Epithelial Model for Realistic, Repeated Inhalation Exposure to Airborne Particles for Toxicity Testing

For toxicity testing of airborne particles, air-liquid interface (ALI) exposure systems have been developed for in vitro tests in order to mimic realistic exposure conditions. This puts specific demands on the cell culture models. Many cell types are negatively affected by exposure to air (e.g., drying out) and only remain viable for a few days. This limits the exposure conditions that can be used in these models: usually relatively high concentrations are applied as a cloud (i.e., droplets containing particles, which settle down rapidly) within a short period of time. Such experimental conditions do not reflect realistic long-term exposure to low concentrations of particles. To overcome these limitations the use of a human bronchial epithelial cell line, Calu-3 was investigated. These cells can be cultured at ALI conditions for several weeks while retaining a healthy morphology and a stable monolayer with tight junctions. In addition, this bronchial model is suitable for testing the effects of repeated exposures to low, realistic concentrations of airborne particles using an ALI exposure system. This system uses a continuous airflow in contrast to other ALI exposure systems that use a single nebulization producing a cloud. Therefore, the continuous flow system is suitable for repeated and prolonged exposure to airborne particles while continuously monitoring the particle characteristics, exposure concentration, and delivered dose. Taken together, this bronchial model, in combination with the continuous flow exposure system, is able to mimic realistic, repeated inhalation exposure conditions that can be used for toxicity testing.

The crystal structure of titanium dioxide nanoparticles influences immune activity in vitro and in vivo

Background

The use of engineered nanoparticles (NP) is widespread and still increasing. There is a great need to assess their safety. Newly engineered NP enter the market in a large variety; therefore safety evaluation should preferably be in a high-throughput fashion. In vitro screening is suitable for this purpose. TiO ₂ NP exist in a large variety (crystal structure, coating and size), but information on their relative toxicities is scarce. TiO ₂ NP may be inhaled by workers in e.g. paint production and application. In mice, inhalation of TiO ₂ NP increases allergic reactions. Dendritic cells (DC) form an important part of the lung immune system, and are essential in adjuvant activity. The present study aimed to establish the effect of a variety of TiO ₂ NP on DC maturation in vitro. Two NP of different crystal structure but similar in size, uncoated and from the same supplier, were evaluated for their adjuvant activity in vivo.

Methods

Immature DC were differentiated in vitro from human peripheral blood monocytes. Exposure effects of a series of fourteen TiO ₂ NP on cell viability, CD83 and CD86 expression, and IL-12p40 and TNF-α production were measured. BALB/c mice were intranasally sensitized with ovalbumin (OVA) alone, OVA plus anatase TiO ₂ NP, OVA plus rutile TiO ₂ NP, and OVA plus Carbon Black (CB; positive control). The mice were intranasally challenged with OVA. OVA-specific IgE and IgG1 in serum, cellular inflammation in bronchoalveolar lavage fluid (BALF) and IL-4 and IL-5 production in draining bronchial lymph nodes were evaluated.

Results

All NP dispersions contained NP aggregates. The anatase NP and anatase/rutile mixture NP induced a higher CD83 and CD86 expression and a higher IL-12p40 production in vitro than the rutile NP (including coated rutile NP and a rutile NP of a 10-fold larger primary diameter). OVA-specific serum IgE and IgG1 were increased by anatase NP, rutile NP, and CB, in the order rutile<anatase<CB. The three particles similarly increased IL-4 and IL-5 production by bronchial LN cells and eosinophils and lymphocytes in the BALF. Neutrophils were induced by rutile NP and CB but not by anatase NP.

Conclusions

Our data show that measuring CD83 and CD86 expression and IL-12p40 and TNF-α production in DC in vitro may provide an efficient way to screen NP for potential adjuvant activity; future studies should establish whether this also holds for other NP. Based on antigen-specific IgE and IgG1, anatase NP have higher adjuvant activity than rutile NP, confirming our in vitro data. Other parameters of the allergic response showed a similar response for the two NP crystal structures. From the viewpoint of safe(r) by design products, rutile NP may be preferred over anatase NP, especially when inhalation exposure can be expected during production or application of the product.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0245-5) contains supplementary material, which is available to authorized users.

A Dose-Response Modeling Approach Shows That Effects From Mixture Exposure to the Skin Sensitizers Isoeugenol and Cinnamal Are in Line With Dose Addition and Not With Synergism

Currently, hazard characterization of skin sensitizers is based on data obtained from studies examining single chemicals. Many consumer products, however, contain mixtures of sensitizers that might interact in such a way that the response induced by a substance is higher than predicted in the hazard assessment. To assess interaction of skin sensitizers in a mixture, a dose-response modeling approach is applied. With this approach, it is possible to assess whether or not responses from mixtures of sensitizers can be predicted from the dose-response information obtained from individual chemicals using dose addition. We selected the skin sensitizers isoeugenol and cinnamal, frequently occurring together in consumer products, to be examined in an adjusted local lymph node assay (LLNA). Cell number and cytokine production (IL-10 and IFN-γ) of the auricular lymph nodes were measured as hallmarks of the skin sensitization response. We found that dose addition for these 2 skin sensitizers closely predicted the effects from mixtures of both chemicals across the broad dose range tested. Hence, isoeugenol and cinnamal show no synergistic effects in the LLNA. Therefore, hazard assessment and risk assessment of these substances can be performed without taking into account mixture exposure.

In vitro effects of low-level aldehyde exposures on human umbilical vein endothelial cells

Aldehydes cause gene expression changes for genes associated with cardiovascular disease. Exposure to aldehydes from tobacco smoke needs to be controlled.

In vitro effects of aldehydes present in tobacco smoke on gene expression in human lung alveolar epithelial cells

Tobacco smoke consists of thousands of harmful components. A major class of chemicals found in tobacco smoke is formed by aldehydes, in particular formaldehyde, acetaldehyde and acrolein. The present study investigates the gene expression changes in human lung alveolar epithelial cells upon exposure to formaldehyde, acrolein and acetaldehyde at sub-cytotoxic levels. We exposed A549 cells in vitro to aldehydes and non-aldehyde chemicals (nicotine, hydroquinone and 2,5-dimethylfuran) present in tobacco smoke and used microarrays to obtain a global view of the transcriptomic responses. We compared responses of the individual aldehydes with that of the non-aldehydes. We also studied the response of the aldehydes when present in a mixture at relative concentrations as present in cigarette smoke. Formaldehyde gave the strongest response; a total of 66 genes were more than 1.5-fold differentially expressed mostly involved in apoptosis and DNA damage related processes, followed by acetaldehyde (57 genes), hydroquinone (55 genes) and nicotine (8 genes). For acrolein and the mixture only one gene was upregulated involved in oxidative stress. No gene expression effect was found for exposure to 2,5-dimethylfuran. Overall, aldehyde responses are primarily indicative for genotoxicity and oxidative stress. These two toxicity mechanisms are linked to respiratory diseases such as cancer and COPD, respectively. The present findings could be important in providing further understanding of the role of aldehydes emitted from cigarette smoke in the onset of pulmonary diseases.

The effect of particle size on the cytotoxicity, inflammation, developmental toxicity and genotoxicity of silver nanoparticles

Silver nanoparticles are of interest to be used as antimicrobial agents in wound dressings and coatings in medical devices, but potential adverse effects have been reported in the literature. The most pronounced effect of silver nanoparticles and the role of particle size in determining these effects, also in comparison to silver ions, are largely unknown. Effects of silver nanoparticles of different sizes (20, 80, 113 nm) were compared in in vitro assays for cytotoxicity, inflammation, genotoxicity and developmental toxicity. Silver nanoparticles induced effects in all endpoints studied, but effects on cellular metabolic activity and membrane damage were most pronounced. In all toxicity endpoints studied, silver nanoparticles of 20 nm were more toxic than the larger nanoparticles. In L929 fibroblasts, but not in RAW 264.7 macrophages, 20 nm silver nanoparticles were more cytotoxic than silver ions. Collectively, these results indicate that effects of silver nanoparticles on different toxic endpoints may be the consequence of their ability to inflict cell damage. In addition, the potency of silver in the form of nanoparticles to induce cell damage compared to silver ions is cell type and size-dependent.

Response of MUTZ-3 dendritic cells to the different components of the Haemophilus influenzae type B conjugate vaccine: towards an in vitro assay for vaccine immunogenicity

Potency testing is mandatory for vaccine registration and batch release. Due to various limitations to in vivo potency testing, there is need for relevant in vitro alternatives. These alternative tests should preferably comprise cells from the target (human) species. The whole suite of immune responses to vaccination that occur in vivo in humans cannot be tested in vitro using a single cell type. Even so, dendritic cells (DC) form an important candidate cell type since they are pivotal in inducing and orchestrating immune responses. Cell lines are preferred over ex vivo cells for reasons of safety, accessibility, and reproducibility. In this first feasibility study we used the human cell line MUTZ-3, because it most closely resembles ex vivo human DC, and compared its response to monocyte-derived DC (moDC). Haemophilus influenzae type B (HiB) vaccine was chosen because its components exert different effects in vivo: while the HiB antigen, polyribosyl ribitol phosphate (PRP) fails to induce sufficient protection in children below 2 years of age, conjugation of this polysaccharide antigen to outer membrane protein (OMP) of Neisseria meningitides, results in sufficient protection. Effects of PRP, OMP, conjugated PRP-OMP, and adjuvanted vaccine (PedVax HiB), on cytokine production and surface marker expression were established. PRP induced no effects on cytokine production and the effect on surface marker expression was limited to a minor decrease in CD209 (DC-SIGN). In both MUTZ-3 and moDC, OMP induced the strongest response both in cytokine production and surface marker expression. Compared to OMP alone conjugated PRP-OMP generally induced a weaker response in cytokine production and surface marker expression. The effects of PedVax HiB were comparable to conjugated PRP-OMP. While moDC showed a larger dynamic range than MUTZ-3 DC, these cells also showed considerable variability between donors, with MUTZ-3 DC showing a consistent response between the replicate assays. In our view, this makes MUTZ-3 DC the cells of choice. In conclusion, our results demonstrate that the MUTZ-3 DC assay allows discrimination between compounds with different immunogenicity. The potential of this cell line as (part of) an in vitro immunogenicity assay should be further explored.

Lipopolysaccharide analogs improve efficacy of acellular pertussis vaccine and reduce type I hypersensitivity in mice

Pertussis is an infectious disease of the respiratory tract that is caused by the gram-negative bacterium Bordetella pertussis. Although acellular pertussis (aP) vaccines are safe, they are not fully effective and thus require improvement. In contrast to whole-cell pertussis (wP) vaccines, aP vaccines do not contain lipopolysaccharide (LPS). Monophosphoryl lipid A (MPL) and Neisseria meningitidis LpxL2 LPS have been shown to display immune-stimulating activity while exerting little endotoxin activity. Therefore, we evaluated whether these LPS analogs could increase the efficacy of the aP vaccine. Mice were vaccinated with diphtheria-tetanus-aP vaccine with aluminum, MPL, or LpxL2 LPS adjuvant before intranasal challenge with B. pertussis. Compared to vaccination with the aluminum adjuvant, vaccination with either LPS analog resulted in lower colonization and a higher pertussis toxin-specific serum immunoglobulin G level, indicating increased efficacy. Vaccination with either LPS analog resulted in reduced lung eosinophilia, reduced eosinophil numbers in the bronchoalveolar lavage fluid, and the ex vivo production of interleukin-4 (IL-4) by bronchial lymph node cells and IL-5 by spleen cells, suggesting reduced type I hypersensitivity. Vaccination with either LPS analog increased serum IL-6 levels, although these levels remained well below the level induced by wP, suggesting that supplementation with LPS analogs may induce some reactogenicity but reactogenicity considerably less than that induced by the wP vaccine. In conclusion, these results indicate that supplementation with LPS analogs forms a promising strategy that can be used to improve aP vaccines.

Lung pathology and immediate hypersensitivity in a mouse model after vaccination with pertussis vaccines and challenge with Bordetella pertussis

While evaluating vaccine efficacy against clinical Bordetella pertussis isolates in mice, after challenge vaccinated mice showed increased lung pathology with eosinophilia, compared to challenged, non-vaccinated animals. This led us to study bacterial clearance, lung pathology, lung TNF-alpha expression, and parameters of immediate hypersensitivity (IH), being serum IgE levels, eosinophil numbers in the bronchoalveolar lavage fluid, and ex vivo IL-4, IL-5, IL-10, IL-13, and IFN-gamma production by the bronchial lymph node cells. BALB/c mice received a combined Diphtheria (D), Tetanus (T), Poliomyelitis, and whole-cell Pertussis vaccine (WCV), a combined D, T, and three-component acellular Pertussis vaccine (ACV), aluminium hydroxide adjuvant, or PBS, 28 and 14 days before B. pertussis infection. Similarly treated non-infected mice were taken as a control. Infection induced pathology; this induction was stronger after (especially WCV) vaccination. WCV but not ACV vaccination induced TNF-alpha expression after challenge. After challenge, IH parameters were strongly increased by (especially ACV) vaccination. Vaccinated IL-4 KO mice showed similar clearance and pathology, in the absence of IgE and with reduced numbers of eosinophils. Vaccinated (Th1-deficient) T-bet KO mice showed reduced clearance and similar pathology. In summary, after challenge vaccination increased lung pathology, TNF-alpha expression (only WCV), and IH parameters. Th1 cells were critical for clearance.

Use of the local lymph node assay in assessment of immune function

The murine local lymph node assay (LLNA) was originally developed as a predictive test method for the identification of chemicals with sensitizing potential. In this study we demonstrated that an adapted LLNA can also be used as an immune function assay by studying the effects of orally administered immunomodulating compounds on the T-cell-dependent immune response induced by the contact sensitizer 2,4-dinitrochlorobenzene (DNCB). C57Bl/6 mice were treated with the immunotoxic compounds cyclosporin A (CsA), bis(tri-n-butyltin)oxide (TBTO) or benzo[a]pyrene, (B[a]P). Subsequently, cell proliferation and interferon-gamma (IFN-gamma) and interleukin (IL)-4 release were determined in the auricular lymph nodes (LNs) after DNCB application on both ears. Immunosuppression induced by CsA, TBTO and B[a]P was clearly detectable in this application of the LLNA. Cytokine release measurements proved valuable to confirm the results of the cell proliferation assay and to obtain an indication of the effect on Th1/Th2 balance. We believe to have demonstrated the applicability of an adapted LLNA as an immune function assay in the mouse.

p53 Heterozygosity Results in an Increased 2-Acetylaminofluorene-Induced Urinary Bladder but not Liver Tumor Response in DNA Repair-Deficient Xpa Mice

Both nucleotide excision repair (NER) and the p53 tumor suppressor protein play crucial roles in the prevention of cells becoming cancerous. This is clearly demonstrated by the fact that NER-deficient xeroderma pigmentosum patients and Li-Fraumeni patients who carry a germ-line p53 mutation are highly tumor prone. The NER-deficient Xpa and the p53(+/-) mouse models clearly mimic their human counterparts, because they are both tumor prone as well. The aim of the study presented here was to analyze the relative contribution of these two pathways in tumor suppression and to analyze a possible link between NER and p53 activation in vivo. For this, we exposed Xpa, p53(+/-), and Xpa/p53(+/-) mice to 2-acetylaminofluorene (2-AAF). We show that 2-AAF-induced urinary bladder tumor suppression is dependent on p53 status, because p53(+/-) mice were highly tumor prone. Xpa/p53(+/-) mice were even more tumor prone, whereas no increased tumor response was found in Xpa mice. Short-term assays revealed a decreased apoptotic response in Xpa/p53(+/-) mice, pointing in vivo toward a link between NER and p53-mediated apoptosis. In contrast, liver tumor response was primarily dependent on appropriate DNA repair, because Xpa-deficient mice were liver tumor prone. p53 heterozygosity had no influence on liver tumor incidences, in line with the results obtained from the short-term 2-AAF studies revealing no altered cellular response in p53(+/-) or Xpa/p53(+/-) mice. Interestingly, however, mice completely deficient in both NER and p53 (Xpa/p53(-/-) mice) showed a dramatic increase of hepatocellular proliferation accompanied by lacZ reporter gene mutations.

Pathogenesis of poliovirus infection in PVRTg mice: poliovirus replicates in peritoneal macrophages

The pathogenesis of poliovirus infection, responsible for the induction of a poliovirus-specific mucosal immune response following intraperitoneal (i.p.) inoculation of virus in mice transgenic for the poliovirus receptor (PVRTg mice), was studied. Following inoculation of poliovirus, replication was determined by increase in virus titre (TCID50) and by PCR of poliovirus-specific negative-strand RNA in peritoneal macrophages, mesenteric lymph nodes, Peyer's patches, duodenum, brain, kidney and liver. The presence of poliovirus antigens in several cell types was detected by immunolabelling. It was demonstrated that poliovirus replicated in the peritoneal macrophages of PVRTg mice, since the virus titre in peritoneal cells was increased compared to the titre in the inoculum. Negative-strand RNA was detected in these cells and most of the poliovirus-immunostained cells had the morphology of macrophages and expressed the macrophage-specific markers CD86 and M1/70 on their surface. Furthermore, in peritoneal lavage, poliovirus was also present in CD19+ B cells, but not in dendritic or T cells. Moreover, poliovirus was detected in macrophage-like cells in the lamina propria of the intestine, but not in epithelial cells. Replication of poliovirus in mesenteric lymph nodes, Peyer's patches and brain was followed by excretion of virus in the faeces. This suggests that the virus is transported due to migration of macrophages from the peritoneal cavity to mesenteric lymph nodes and the lamina propria of Peyer's patches. It is likely that this route is responsible for the induction of virus-specific IgA in the gut.

Association of Bordetella pertussis with host immune cells in the mouse lung

Mouse models are frequently used to study immunity and pathogenesis to Bordetella pertussis infection. To improve the understanding of the mouse infection model, the influx of host cells and B. pertussis localisation in the lungs were evaluated. Furthermore, the roles of filamentous hemagglutinin (FHA) and fimbriae (Fim) in these processes were determined. B. pertussis infection stimulated the recruitment of polymorphonuclear granulocytes (PMN), alveolar macrophages, and lymphocytes. As determined by double immunofluorescence staining, 2 hr after infection most B. pertussis were free in the alveolar space, some were attached to alveolar epithelia, and some were associated with and phagocytosed by PMN. After 3 days, most bacteria were associated with and phagocytosed by macrophages, some by PMN. B. pertussis was shown not to be ingested by epithelial cells or associated with interstitial macrophages. B. pertussis mutants lacking expression of FHA or Fim were associated with and phagocytosed by the same cell types as parental bacteria. The Fim mutant, however, induced a more severe inflammation, and was cleared faster from the lungs compared to the parental strain and the FHA mutant. These results suggest that Fim does not affect bacterial localisation in the mouse lung, but does influence host immune mechanisms. Possibly, Fim may exert an anti-inflammatory function and thereby inhibit killing by macrophages.

Developmental changes in NMDA-induced cell swelling and its transition to necrosis measured with 1H magnetic resonance imaging, impedance and histology

The vulnerability of the rat brain to intracerebrally injected N-methyl-D-aspartate (NMDA) drastically changes with age. We evaluated the developmental changes in the early and late responses to NMDA using 1H magnetic resonance imaging (MRI), cortical impedance and histology. NMDA, injected in the striatum of rats at postnatal days (P) 4, 7, 10, 14 and 21, induced a significant age-dependent reduction in the apparent diffusion coefficient (ADC) of tissue water in the striatum and the cerebral cortex monitored 1 h later using diffusion-weighted MRI. The reduction in ADC amounted 65% at P4 with lower values thereafter and was about 30% at P21. NMDA similarly induced a reduction in the cortical extracellular space (by 50% at P7 and 10% at P16) as measured with impedance recordings. The progressive decrease in the effect of NMDA with brain development was also indicated by a decrease in the volume of tissue in which the changes in ADC occurred (50 mm3 at P4 and 8 mm3 at P21). The diffusion of extracellular tracer molecules Mn2+ or [3H]-(R)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) injected in the striatum and monitored with T1-weighted MRI and autoradiography respectively showed a similar age dependence with the diffusion volume being twofold larger in P7 than in P21 brain. Thus restriction in diffusion during brain development may contribute to the decrease in NMDA-induced injury with age. The volume of tissue necrosis and gliosis, measured with T2-weighted MRI and histology 5 days after NMDA injection, was similar to that outlined by the ADC reduction detected soon after the insult at P4, P7 and P21. However, at P10 and P14 only 50% of the tissue showing a hyperintense signal in DW images displayed necrosis and gliosis 5 days later. This study shows that during development the early response to NMDA in terms of cytotoxic cell swelling (indicated both with impedance recordings and diffusion-weighted MRI) decreases with age. In addition, with maturation only part of the brain tissue acutely affected by NMDA does proceed into necrosis and gliosis, indicating an increased capacity of cells in the developing rat brain to survive NMDA-induced cell swelling.

Microwave-enhanced in situ end-labeling of fragmented DNA: parametric studies in relation to postmortem delay and fixation of rat and human brain

In situ end-labeling (ISEL) identifies DNA fragmentation in apoptotic or necrotic nuclei in tissue sections. However, application of ISEL on human brain requires conservation of DNA integrity during the postmortem delay (PMD) and good accessibility of fragmented DNA after (prolonged) tissue fixation. We therefore investigated ISEL in relation to PMD and fixation in rat and human brain. Application on a unilateral lesion model in perfused rat brain revealed that prolonged post-fixation strongly diminished ISEL results. However, microwave pre-treatment can counteract these masking effects without inducing nonspecific labeling contralaterally. On the other hand, in briefly post-fixed, perfused brain or immersion-fixed rat and human PMD brain, microwave pre-treatment was deleterious and induced strong nonspecific labeling. In young rat brain, PMD did not influence the low numbers of apoptotic nuclei until 24 hr PMD, when massive nuclear labeling occurred. In human cortex, DNA fragmentation patterns were independent of duration of fixation or PMD and were already present from 4.25 hr PMD onwards. Our data suggest that ISEL on human brain represents antemortem DNA damage rather than PMD artifacts. Furthermore, microwave pre-treatment appears beneficial only in particular fixation conditions.

Treatment with NMDA receptor antagonists does not affect developmental changes in NMDA receptor properties in vivo

Effects of acute and long-term treatment of neonatal rats with N-methyl-D-aspartate (NMDA) receptor antagonists on changes in NMDA receptor properties were examined. Animals received either on postnatal day 6 a single dose of the antagonists MK-801 (1 mg/kg), or D-CPPene (2 mg/kg) or during the period from postnatal day 5 to 14, two daily injections of MK-801 (0.25 mg/kg) or D-CPPene (0.75 mg/kg). Control littermates received saline injections. In both cases animals were sacrificed one day after the last injection. NMDA receptor properties were examined in membrane preparations derived from the cerebral cortex by studying the modulation of [3H]MK-801 binding by glutamate, Mg2+ and D-CPPene. The density of agonist- and antagonist-binding sites in the CA1 region of the hippocampus were determined by autoradiography, using [3H]CGP39653 or [3H]glutamate as ligands. A significant developmental increase in NMDA receptor binding sites was detected both in preparations of cerebral cortical membranes and in the CA1 area of the hippocampus. In addition, the Mg2+ sensitivity of [3H]MK-801 binding was significantly higher in membrane preparations from the cerebral cortex of postnatal day 15 compared to postnatal day 7 animals. Neither the single nor the subchronic treatment with NMDA receptor antagonists exerted a significant influence on the density of antagonist binding sites or on the modulation of [3H]MK-801 binding by glutamate, Mg2+ or D-CPPene. We conclude therefore that neonatal treatment with NMDA receptor antagonists in vivo does not involve significant alterations in the properties and the densities of NMDA receptors in the brain regions studies, i.e., during the period when expression of these receptors is subject to pronounced developmental regulation.

NMDA and kainate induce internucleosomal DNA cleavage associated with both apoptotic and necrotic cell death in the neonatal rat brain

Injection of N-methyl-D-aspartate (NMDA) or kainate in the striatum of 7-day-old rats induced massive cell loss in the ipsilateral striatum, hippocampus and inner cortical layers. In order to examine whether apoptosis contributes to cell death in this model of excitotoxic injury we examined the progression of internucleosomal DNA fragmentation and changes in cellular ultrastructure. Agarose gel electrophoresis of DNA extracted from the ipsilateral striatum, cerebral cortex and hippocampus clearly showed breakdown of DNA into oligonucleosome-sized fragments, indicative of apoptosis, 12 h post-NMDA injection. In addition, an increase between 12 and 24 h was observed as well as a continuous presence 5 days later. Kainate induced a similar time course of oligonucleosomal DNA fragmentation, but the intensity of the ethidium bromide stained bands was less compared with that observed for NMDA. DNA fragmentation was not detected in animals intrastriatally injected with Tris-HCl or in animals treated with MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohept-5,10-imine hydrogen maleate, 1 mg/kg] 30 min after NMDA injection. MK-801 had no effect on DNA fragmentation induced by kainate. In addition to agarose gel electrophoresis, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labelling (TUNEL) was used for detection of DNA fragmentation in sections. A gradual increase in the density of both apoptotic and non-apoptotic TUNEL nuclei was found in the anterior cingulate (ACC) and retrosplenial (RSC) areas of the cortex, the striatum, and the CA1 area and dentate gyrus of the hippocampus over the first 24 h post-NMDA or kainate injection. In the contralateral hemisphere hardly any TUNEL nuclei were present and their density was comparable with that in animals injected with vehicle only. In the ipsilateral mammillary nucleus (MN), which showed no signs of acute cell swelling after intrastriatal injection with NMDA, internucleosomal DNA fragmentation was found 24 and 48 h after intrastriatal NMDA injection. Here, the density of TUNEL cells with apoptotic morphology was high at 12 and 24 h post-NMDA injection but returned to control levels by 5 days. Electron microscopy showed cells with a clearly apoptotic morphology in the ACC and RSC and in the MN 24 h after NMDA injection. In the CA1 area of the hippocampus a necrotic, rather than an apoptotic, ultrastructure prevailed, indicating that the TUNEL method stained both apoptotic and necrotic cells.(ABSTRACT TRUNCATED AT 400 WORDS)

NMDA receptor levels in chronically depolarized long-term neonatal rat neocortical explants

The levels of the N-methyl-D-aspartate subclass of glutamate receptor were determined in organotypic neocortical explants chronically exposed to a growth medium containing 25 mM potassium (K25). Explants exposed to 25 mM potassium for 2-3 weeks evinced significantly less binding of the non-competitive N-methyl-D-aspartate receptor-associated channel antagonist 125I-MK801 than did age-matched controls. Surprisingly, cultures that were returned to control growth medium for a further 2 or 7 days showed even less binding of the ligand. The Kd values of binding were not affected and were similar to those of fresh postnatal cortex. The maximum number of binding sites did not vary between postnatal day 6 and 14 days in vitro control cultures, but were significantly less than those measured at postnatal day 20 (comparable age: 14 days in vitro). Several conclusions can be drawn from these findings: (i) the density of the N-methyl-D-aspartate subclass glutamate receptor does not attain in vivo levels under the present culturing conditions, but remains at those levels associated with the stage of development at which the tissue was brought into culture, (ii) chronic depolarization results in a drastic reduction in N-methyl-D-aspartate receptor density, which is not compensated for after the return to normal growth conditions, (iii) depolarization selectively inhibits cellular maturation of the neocortex (but not survival, as shown previously), including neurotransmitter receptor production and/or insertion into membranes or assembly.

A case of Wegener's granulomatosis presenting with jaw claudication

The major manifestations of Wegener's granulomatosis have been well described. Jaw claudication has not been recognized as one of the symptoms associated with this disease. We report the first case of Wegener's granulomatosis presenting with jaw claudication. Documentation of different histological types of vasculitis producing similar symptoms broadens our concepts of systemic vasculitis and emphasizes the need for tissue biopsy for diagnosis.