Department of Immunotoxicology, Institute for Risk Assessment Sciences, Utrecht University, 3584 CM Utrecht, The Netherlands
1 To whom correspondence should be addressed at Institute for Risk Assessment Sciences, Department of Immunotoxicology, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands. Fax: +31302535077. E-mail: C.deHaar{at}iras.uu.nl.
Received June 13, 2005; accepted July 15, 2005
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ABSTRACT |
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Key Words: ultrafine particles; adjuvant; allergy; intranasal; inflammation.
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INTRODUCTION |
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In both humans (Diaz-Sanchez et al., 1999; Fujieda et al., 1998
) and animals (Lambert et al., 2000
; Nilsen et al., 1997
; Steerenberg et al., 2003
; van Zijverden et al., 2001
; Whitekus et al., 2002
) inhalation or intranasal exposures to various PM (e.g., diesel exhaust particles [DEP], CBP, or residual oil fly ash [ROFA]) in combination with an antigen is capable of increasing levels of antigen-specific IgE. Because IgE is involved in type 1 allergic responses, it is involved in allergic asthma as well as other allergic diseases. Therefore IgE is used to assess the adjuvant potential of particles (Nilsen et al., 1997
; Takafuji et al., 1987
; Takano et al., 1997
; van Zijverden et al., 2001
) on allergic sensitization. Some of these studies also show the development of allergic airway inflammation, and airway hypersensitivity after antigen challenge (Fernvik et al., 2002
; Lambert et al., 1999
; Steerenberg et al., 2003
).
The mechanisms behind this adjuvant activity of particles are still not clear. Apart from the role of particles as antigen depot (Gupta, 1998), the induction of local inflammatory responses may also be of importance. Various particle characteristics have been associated with particle-induced airway inflammation. Lambert et al. (2000)
, showed that transition metals are involved in ROFA-induced airway inflammation and adjuvant activity. Other factors that might be important are PAH from DEP (Diaz-Sanchez, 1997
), biologics like endotoxins attached to freshly isolated PM (Soukup and Becker, 2001
), or a combination of both (Yanagisawa et al., 2003
). Particle size and surface area are also important factors in particle airway-toxicity (Brown et al., 2000
) and have recently been shown, with the popliteal lymph node assay, to be important factors in adjuvant activity (Nygaard et al., 2004
).
Because our previous studies (van Zijverden et al., 2001) have shown that ultrafine CBP and DEP have adjuvant activity after combined intranasal exposure with OVA, we wanted to investigate the airway inflammatory effects early after intranasal exposure. We have used ultrafine CBP in the current study, because we were interested in the toxicity and adjuvant activity of particles per se. Furthermore, the particle core of most of the real-life PM, like, for instance, DEP, consist of carbon, making these particles relevant to real-life exposures. Ultrafine CBP has also been shown to induce an airway inflammation in rat models that was independent of any soluble factors (Brown et al., 2000
) So, in the current study we examined particle-induced toxicity and local airway inflammation using different doses of CBP with a constant dose of OVA, and in addition assessed whether immune sensitization occurred.
Th2 cytokines have been shown to play an important role in both the sensitization and the challenge phases of allergic airway disease. We therefore determined cytokine production by cells obtained from the lungs and lung draining lymph nodes at day 8 (sensitization) and at day 28 (after challenge). In addition, we measured antigen-specific serum IgE levels, and allergic airway inflammation upon antigen challenge.
Our data show that CBP-induced local airway damage and inflammation is detectable 24 h after the last intranasal exposure (day 4), and that Th2 skewing of the immune response against the co-administered OVA is already apparent on day 8. These CBP+OVA effects were only present in mice treated with 200 µg CBP, and this high-dose group also showed increased OVA-specific IgE and allergic airway inflammation after antigen challenge.
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MATERIALS AND METHODS |
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Intranasal sensitization and challenge.
Carbon black (CBP) particles were obtained from Brunschwich Chemicals (Amsterdam, The Netherlands) and particle diameter was determined using electron microscopy (approximately 3050 nm). Particles were suspended in phosphate buffered saline (PBS) at a concentration of 3.3 mg/ml, and sonicated using a Branson 1510 Ultrasonic bath (Branson, Danbury, CT) for 2 h. After sonification, the suspensions were 1:10 and 1:100 diluted in PBS to achieve the desired concentration series.
OVA (Sigma-Aldrich, Zwijndrecht, The Netherlands) was prepared in PBS, and endotoxin was removed with Pierce detoxigel (Perbio Science, Etten-Leur, The Netherlands). Endotoxin levels were 0.6 ng/mg OVA, and no endotoxin could be detected in CBP as determined by Limulus Amebocyte Lysate (LAL) assay (LAL Kinetic-QCL Kit, Bio-Whittaker, Walkersville, MD). OVA was added to the CBP suspensions to a final concentration of 0.5 mg/ml. Mice were anesthetized by intramuscular injection of 40 µl ketamine (25 mg/ml)/xylazine (5 mg/ml), and exposed to 20 µl of OVA (0.5 mg/ml) or 200 µg, 20 µg, 2 µg CBP+OVA (3.3, 0.33, 0.033 mg/ml CBP in combination with 0.5 mg/ml OVA, respectively) in PBS by intranasal droplet application on days 0, 1, and 2.
Mice were sacrificed at day 4 and day 8 by an overdose of pentobarbital, or they were challenged to allow study of asthma-like allergic airway inflammation. On days 25, 26, and 27, a challenge was performed by intranasal droplet application of 20 µl OVA (0.5 mg/ml) in PBS or PBS only to mice anesthetized by intramuscular injection of 40 µl ketamine (25 mg/ml)/xylazine (5 mg/ml). Mice were sacrificed on day 28 by an overdose of pentobarbital.
Bronchoalveolar lavage.
Bronchoalveolar lavage (BAL) was performed by flushing the lungs with 3 * 1 ml sterile PBS 24 h after the last intranasal exposure. The first lavage was kept separate from the other two. BAL was centrifuged at 900 x g for 5 min, and the BAL fluid (BALF) from the first lavage was stored at 80°C and used for further analysis. The cells from all three lavages were pooled. Total BAL cell numbers were counted with a Coulter counter (Coulter Electronics, Luton, UK), and differential cell count was performed under FACS staining.
Lactate dehydrogenase (LDH), total protein, and tumor necrosis factor alpha (TNF-) levels were determined in first BALF fraction using a TOX-7 kit (Sigma-Aldrich Zwijndrecht, The Netherlands), a Pierce BCA kit (Perbio Science, Etten-Leur, The Netherlands), and a TNF-
ELISA kit (Biosource Europe, Fleurus, Belgium), all according to the manufacturers' protocols.
Isolation and culture of lymph node and lung tissue cells.
Lungs were perfused with 10 ml sterile PBS through the right ventricle to remove blood from the lungs. Lungs were isolated and chopped with sterile blades and digested with collagenase IV and DNAse I, as described previously (Vermaelen et al., 2001). Peribronchial lymph nodes (PBLN) were isolated and minced using frosted objective slides. Single cell suspensions from both organs were taken up in complete RPMI 1640 with Glutamax-I (Invitrogen Life Technologies) supplemented with 10% FCS (Valeant) and 2% penicillin-streptomycin.
Cell suspensions were plated in round-bottom 96-well plates (2 * 106 cells/ml) and restimulated with 100 µg OVA for 4 days. Levels of IL-4, IL-5, IL-10, and IFN- in culture supernatants were measured by ELISA (BD Pharmingen, Hamburg, Germany) according to the manufacturer's protocol.
Flow cytometry.
Cells from BAL, lungs, and PBLN were stained with FITC-labeled anti-GR-1, PE-labeled anti-B220, and APC-labeled anti-CD11c. Cells from lungs and PBLN were also stained with FITC-labeled anti-CD4, PE-labeled anti-CD8, PerCP-labeled anti-CD3, and APC-labeled CD19. Cells were incubated with Fc block (2.4G2 Ab) for the reduction of nonspecific Ab binding, and staining was performed at 4°C. Antibodies used were from BD Pharmingen (San Diego, CA) and cells were measured using a FACScan and analyzed using CellQuest software (BD Bioscience). Dead cells and debris were excluded from BAL samples using propidium iodide staining (Sigma-Aldrich) and detection in FL-3.
Determination of OVA-specific IgE.
Serum was collected on days 21 and 28 after the start of intranasal exposures. OVA-specific IgE antibody levels were determined by means of a sandwich ELISA. Briefly, plates (high bond 3950; Costar, Cambridge, MA) were coated overnight at 4°C with 2 µg/ml rat anti-mouse IgE antibody (Pharmingen) in 0.05 M bicarbonate buffer (pH 9.6), and blocked with PBS containing 0.05% Tween 20 (PBS-T) and 3% milk powder (Campina Melkunie) (1 h, 37°C). Serum was serially diluted in PBS-T containing 1% bovine serum albumin (PBS-T 1% BSA) and incubated for 1 h at 37°C. This was followed by a 1 h incubation with biotinylated OVA. After incubation with poly-HRP-streptavidin (Sanquin, Amsterdam, The Netherlands) (1 h, RT), TMB substrate was added (15 min, RT). The coloring reaction was stopped by adding 2 M H2SO4, and absorbance was measured at 450 nm and compared between treatment groups.
Lung histology.
Lungs were inflated with 1 ml of 4% formalin in PBS, and paraffin-embedded. Sections (5 µm thick) were stained with hematoxylin and eosin (H&E) or periodic acidSchiff (PAS) and examined by light microscopy.
Statistical analysis.
Data are presented as mean values ± standard error of the mean (SEM), and are representative of at least two independent experiments. Because our data were not normally distributed, they did not meet the assumptions needed for analysis of variance (ANOVA). Therefore we used the nonparametric Kruskal-Wallis test for multiple independent samples, followed by a Mann-Whitney U-test to compare the different treatment groups. When concentrations were not detectable (ND), they were set at 0 for statistical analysis (see Table 2). All tests were performed using SPSS software 12.0 for Windows. Data are considered significant when p values are <0.05.
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RESULTS |
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Although doses of 200 µg , 20 µg , and 2 µg CBP combined with OVA were tested, only exposure to 200 µg CBP+OVA induced significantly (p = 0.004) higher numbers of BAL cells compared to the OVA control (Fig. 2A). BAL contained many neutrophils, whereas eosinophils and macrophages were only slightly increased. Other inflammatory parameters like total protein (Fig. 2B) and TNF- (Fig. 2C) levels in the BALF were also increased only in mice exposed to 200 µg CBP.
Carbon black particles were seen in the airways Lumen and inside alveolar macrophages (histology, data not shown). The RAS of the alveolar macrophages, which can be used as a parameter for phagocytosis (Stringer et al., 1995) was increased dose dependently. Whereas both 200 µg and 20 µg of CBP+OVA induced RAS levels that where significantly higher (p = 0.004) than those of the OVA controls, 2 µg of CBP+OVA did not (Fig. 2D). Furthermore, the RAS of the macrophages of the 200-µgdosed animals were significantly increased compared to the 20-µgdosed animals (p = 0.041).
Dose-Dependent CBP+OVA Adjuvant Activity on PBLN
On day 8 the total number of lymphocytes in the PBLN (Fig. 3) was significantly increased 45-fold in the 200 µg CBP+OVA-exposed group compared to the OVA control (p = 0.004) and the 20-µg and 2-µgexposed groups (p = 0.015 and p = 0.002). The increase in PBLN cell number was mainly attributable to the increase in CD19 cells (78 times increase), whereas the number of CD4 and CD8 cells was doubled that of the other treatments. The 20-µg and 2-µg exposures did not increase the number of PBLN cells compared to the OVA control.
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CBP+OVA Sensitization Induces Systemic IgE Production
To further study local and systemic sensitization only the 200-µg CBP dose combined with OVA and OVA alone were used. OVA-specific IgE levels were measured on day 21, and again on day 28 (after intranasal challenges at days 25, 26, and 27). Figure 4 shows that OVA-specific IgE levels were significantly (p = 0.035) increased at day 21 in serum of CBP+OVA-exposed mice (Fig. 4A). The IgE levels of mice sensitized with CBP+OVA were even higher on day 28 (p < 0.02) (Fig 5B), whereas OVA-specific IgE levels were not significantly different after a challenge with PBS or OVA (Fig 5B).
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The cytokine profile after challenge matched the skewed profile of the 200-µg CBP+OVA-dosed group observed at day 8, but with even more pronounced and higher levels of Th2 cytokines IL-4, IL-5, and IL-10 compared to IFN- (Table 2). Like the IgE-levels, PBLN cell numbers in mice treated with CBP+OVA and challenged with PBS were higher than those of mice treated with OVA and challenged with PBS. In both treatment groups, the cytokine production by PBLN cells after PBS challenge was very low. Only the levels of IL-5 were significantly (p < 0.021) higher in the CBP+OVA/PBS group compared to the OVA/PBS groups (Table 2).
After expansion in the PBLN, effector T cells are able to migrate to the lungs, where they can be reactivated by local antigen-presenting cells. Figure 5B shows that the number of lung lymphocytes was significantly higher in CBP+OVA/OVA-treated animals than in OVA/OVA-treated or CBP+OVA/PBS-treated mice (p = 0.029), and that no differences were found between OVA/PBS and OVA/OVA, or between OVA/PBS and CBP+OVA/PBS treatments, respectively. The higher lung lymphocyte numbers were caused mainly by higher numbers of CD4 and CD19 (23 times increased). Lung lymphocytes from both OVA- and CBP+OVA-treated mice produced clearly higher levels of cytokines after OVA challenge than after PBS challenge (Table 2), but in the case of CBP+OVA, the production of IL-5 and IL-10 was four to five times higher than in OVA-treated mice. In both OVA-challenged groups the cytokine profile was reminiscent of the Th2-skewed immune response (Table 2). When the production of cytokines was compared between PBLN and lung lymphocytes, the profile was comparable, although the increases in cytokine production by PBLN were substantially higher.
Intranasal Challenge with OVA Induces Asthma-Like Airway Inflammation in CBP+OVA-Sensitized Mice
Antigen-specific airway challenge of Th2-sensitized mice is known to induce strong eosinophilic airway inflammation (van Rijt et al., 2002). The total number of cells in the BAL was increased tenfold (p = 0.019) in mice sensitized with CBP+OVA and challenged with OVA (Fig. 6A). Although all cell types were increased, the eosinophils were increased the most in the CBP+OVA/OVA-treated mice, with cell numbers that were 50 times higher compared to all other groups. The airway inflammation was also confirmed by histological examination, showing perivascular and peribronchial infiltrates, and goblet cell hyperplasia in CBP+OVA/OVA-treated mice (Fig. 6E), whereas the other groups showed no histological changes (Fig. 6B-D). Together, our findings indicate that antigen-specific inflammation with predominantly eosinophilic influx is induced only in CBP+OVA-sensitized mice.
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DISCUSSION |
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Various rat studies have shown that CBP induce acute airway inflammation early after intratracheal exposure (Brown et al., 2000; Gilmour et al., 2004
). The inflammation in these studies was characterized by increased levels of LDH, total protein, TNF-
, neutrophils, eosinophils, and lymphocytes in the BALF. In the present study, 200-µg CBP+OVA exposure also caused an increase in LDH, total protein levels, and inflammatory cells, all findings indicative of airway damageinduced local inflammation. Because only the 200-µg CBP+OVA concentration induced local inflammation and had immune adjuvant activity, our data confirm data reported by other investigators (Lambert et al., 1999
; Saxon and Diaz-Sanchez, 2005
; Whitekus et al., 2002
) and suggest that airway damage plays an important role in the adjuvant activity of air pollution.
Whereas, the 200-µg dose of CBP may be considered high compared environmental exposures to particles in humans, toxicity and induction of inflammation of the airways is shown in humans after exposure to particles (Ghio and Huang, 2004). The suggested role of particle toxicity on particle adjuvant activity in animal studies may therefore be one possible mechanism of increased allergic disease at sites with high air pollution.
Various different particle characteristics like polycyclic aromatic hydrocarbons (PAHs) (Diaz-Sanchez et al., 1997), transition metals (Lambert et al., 2000
), surface area (Nygaard et al., 2004
), oxidative potential (Whitekus et al., 2002
), and biologics (Soukup and Becker, 2001
) are known to influence airway responses to particles and adjuvant activity. Because the ultrafine CBP used in the present studies does not contain PAHs or biologics, and because transition metals are probably not involved in the CBP toxicity (Brown et al., 2000
), we suggest that physicochemical particle characteristics like surface area, charge, and oxidative potential may be involved.
Based on present findings, we suggest that particles like CBP induce airway hypersensitivity to bystander antigens as follows. Initially, inhaled particles such as CBP reach and interact with the lung epithelial cells and alveolar macrophages depending on their size and charge. Ultrafine particle that have oxidative potential can directly damage these cells if the antioxidant effect of the epithelial lining fluid falls short (Greenwell et al., 2002). Apart from directly damaging the cells, uptake of the particles can also activate epithelial cells and alveolar macrophages to produce reactive oxygen species, activate nuclear factor kappa B (NF
B) and synthesize and secrete proinflammatory cytokines like TNF-
(Lambert et al., 2001
; Li et al., 2003
; Tao and Kobzik, 2002
). Disruption of the epithelial barrier, which will further increase in response to increased levels of proinflammatory cytokines (Coyne et al., 2002
), will allow antigens like OVA to become more easily available to antigen-presenting dendritic cells (Lambert et al., 1999
).
Dendritic cells are constantly taking up antigen from the airways. After uptake of the antigen, a portion of the dendritic cells will migrate to the local lymph node to present the antigen to naïve T cells, without fully maturing. Although the presentation of antigen by dendritic cells is enough to induce some T-cell proliferation, it will normally lead to the induction of tolerance. Increased levels of co-stimulation are needed to induce immune sensitization against the presented antigen (Lambrecht and Hammad, 2003). Increased migration, maturation of dendritic cells, including increased MHCII antigen presentation and upregulation of co-stimulatory molecules, is induced by proinflammatory cytokines (Banchereau and Steinman, 1998
). This finding is supported by a study in which co-exposure to TNF-
and antigen induced a state of immune sensitization comparable to that observed after exposure to ROFA and antigen (Lambert et al., 2001
). The importance of oxidative stress and ensuing toxicity is strengthened by studies showing that particle-induced TNF-
release from macrophages in vitro (Brown et al., 2004
) and inflammatory responses in vivo (Dick et al., 2003
) can be partially inhibited by antioxidants. Another study (Whitekus et al., 2002
) demonstrated that the adjuvant effect of DEP on IgE production could also be partially inhibited by antioxidants. Whereas the depot function is not mentioned in the mechanism described here, it may make an important contribution to the immune adjuvant potential. Both the concentration of antigen and its prolonged presence may help to further increase the response.
In the present study the early inflammation in the airways, after the 200-µg CBP+OVA exposure was soon followed by a type 2-skewed immune sensitization. This type 2-skewed response was apparent from cytokine production profiles in the PBLN, both early after induction of sensitization (day 8) and again after challenge (on day 28). Interestingly, although the increase in cytokine levels was less pronounced on day 8 than on day 28, the Th2 cytokine profiles on those days were comparable. Using the mouse model described here, the cytokine profile observed in PBLN cells ex vivo stimulated with OVA, apparently may be used early after sensitization to predict the skewing of the immune response that may eventually develop.
Our data with regard to cytokine production by lymphocytes from PBLN and lungs demonstrate and confirm data reported by others that airway exposure to particles and antigens elicits a Th2 cytokine profile (Fujimaki et al., 1994). Locally produced cytokines are important for the clinical manifestations of the allergic airway inflammation. Taking this view, it is interesting that lung lymphocytes isolated from mice sensitized with CBP+OVA and challenged with OVA produce high amounts of the Th2 cytokines, in particular, IL-5. Notably IL-5 is crucial in eosinophilic airway inflammation (Hamelmann et al., 2000
). In addition and intriguingly, in time, lung lymphocytes produce more IL-10 than IL-5 (and IL-4). Whereas IL-10 is often regarded as a Th2 cytokine and is shown to be critical for the development of asthma-like responses like IL-5 production, eosinophilia, and mucus secretion (Yang et al., 2000
), IL-10 is also known to have regulatory effects, especially on different innate cells such as macrophages. Moreover, IL-10 is shown to inhibit particle-induced cytokine production from macrophages (Im and Han, 2001
). Both IL-10 effects mentioned here may be involved in our model, helping the induction of a Th-2 response (early after CBP+OVA exposure) and possibly inhibiting innate immune cells at the effector phase of the allergic response.
In conclusion, the current kinetic data on particle-induced inflammation and immune sensitization suggest a causal relation between CBP toxicity and immune adjuvant activity. Furthermore, the cytokine profile on day 8 in the airways, in particular in the PBLN, seems predictive of the allergic airway sensitization. This has important implications not only for studying underlying mechanisms, but also for designing assays to predict the sensitizing potential of particles.
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ACKNOWLEDGMENTS |
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REFERENCES |
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Brown, D. M., Donaldson, K., Borm, P. J., Schins, R. P., Dehnhardt, M., Gilmour, P., Jimenez, L. A., and Stone, V. (2004). Calcium and ROS-mediated activation of transcription factors and TNF- cytokine gene expression in macrophages exposed to ultrafine particles. Am. J. Physiol. Lung Cell Mol. Physiol. 286, L344L353.
Brown, D. M., Stone, V., Findlay, P., MacNee, W., and Donaldson, K. (2000). Increased inflammation and intracellular calcium caused by ultrafine carbon black is independent of transition metals or other soluble components. Occup. Environ. Med. 57, 685691.
Brown, D. M., Wilson, M. R., MacNee, W., Stone, V., and Donaldson, K. (2001). Size-dependent proinflammatory effects of ultrafine polystyrene particles: A role for surface area and oxidative stress in the enhanced activity of ultrafines. Toxicol. Appl. Pharmacol. 175, 191199.[CrossRef][ISI][Medline]
Coyne, C. B., Vanhook, M. K., Gambling, T. M., Carson, J. L., Boucher, R. C., and Johnson, L. G. (2002). Regulation of airway tight junctions by proinflammatory cytokines. Mol. Biol. Cell 13, 32183234.
D'Amato, G. (2002). Environmental urban factors (air pollution and allergens) and the rising trends in allergic respiratory diseases. Allergy 57(Suppl. 72), 3033.[CrossRef][Medline]
De Heer, H. J., Hammad, H., Soullie, T., Hijdra, D., Vos, N., Willart, M. A., Hoogsteden, H. C., and Lambrecht, B. N. (2004). Essential role of lung plasmacytoid dendritic cells in preventing asthmatic reactions to harmless inhaled antigen. J. Exp. Med. 200, 8998.
Diaz-Sanchez, D. (1997). The role of diesel exhaust particles and their associated polyaromatic hydrocarbons in the induction of allergic airway disease. Allergy 52, 5256; discussion 5758.[ISI][Medline]
Diaz-Sanchez, D., Garcia, M. P., Wang, M., Jyrala, M., and Saxon, A. (1999). Nasal challenge with diesel exhaust particles can induce sensitization to a neoallergen in the human mucosa. J. Allergy Clin. Immunol. 104, 11831188.[ISI][Medline]
Diaz-Sanchez, D., Tsien, A., Fleming, J., and Saxon, A. (1997). Combined diesel exhaust particulate and ragweed allergen challenge markedly enhances human in vivo nasal ragweed-specific IgE and skews cytokine production to a T helper cell 2-type pattern. J. Immunol. 158, 24062413.[Abstract]
Dick, C. A., Brown, D. M., Donaldson, K., and Stone, V. (2003). The role of free radicals in the toxic and inflammatory effects of four different ultrafine particle types. Inhal. Toxicol. 15, 3952.[CrossRef][ISI][Medline]
Donaldson, K., Stone, V., Borm, P. J., Jimenez, L. A., Gilmour, P. S., Schins, R. P., Knaapen, A. M., Rahman, I., Faux, S. P., Brown, D. M. et al. (2003). Oxidative stress and calcium signaling in the adverse effects of environmental particles (PM10). Free Radic. Biol. Med. 34, 13691382.[CrossRef][ISI][Medline]
Fernvik, E., Peltre, G., Senechal, H., and Vargaftig, B. B. (2002). Effects of birch pollen and traffic particulate matter on Th2 cytokines, immunoglobulin E levels and bronchial hyper-responsiveness in mice. Clin. Exp. Allergy 32, 602611.[CrossRef][ISI][Medline]
Fujieda, S., Diaz-Sanchez, D., and Saxon, A. (1998). Combined nasal challenge with diesel exhaust particles and allergen induces in vivo IgE isotype switching. Am. J. Respir. Cell Mol. Biol. 19, 507512.
Fujimaki, H., Nohara, O., Ichinose, T., Watanabe, N., and Saito, S. (1994). IL-4 production in mediastinal lymph node cells in mice intratracheally instilled with diesel exhaust particulates and antigen. Toxicology 92, 261268.[CrossRef][ISI][Medline]
Gallucci, S., and Matzinger, P. (2001). Danger signals: SOS to the immune system. Curr. Opin. Immunol. 13, 114119.[CrossRef][ISI][Medline]
Ghio, A. J., and Huang, Y. C. (2004). Exposure to concentrated ambient particles (CAPs): A review. Inhal. Toxicol. 16, 5359.[CrossRef][ISI][Medline]
Gilmour, P. S., Ziesenis, A., Morrison, E. R., Vickers, M. A., Drost, E. M., Ford, I., Karg, E., Mossa, C., Schroeppel, A., Ferron, G. A. et al. (2004). Pulmonary and systemic effects of short-term inhalation exposure to ultrafine carbon black particles. Toxicol. Appl. Pharmacol. 195, 3544.[CrossRef][ISI][Medline]
Greenwell, L. L., Moreno, T., Jones, T. P., and Richards, R. J. (2002). Particle-induced oxidative damage is ameliorated by pulmonary antioxidants. Free Radic. Biol. Med. 32, 898905.[CrossRef][ISI][Medline]
Gupta, R. K. (1998). Aluminum compounds as vaccine adjuvants. Adv. Drug Deliv. Rev. 32, 155172.[CrossRef][ISI][Medline]
Hamelmann, E., Takeda, K., Haczku, A., Cieslewicz, G., Shultz, L., Hamid, Q., Xing, Z., Gauldie, J., and Gelfand, E. W. (2000). Interleukin (IL)-5 but not immunoglobulin E reconstitutes airway inflammation and airway hyperresponsiveness in IL-4-deficient mice. Am. J. Respir. Cell Mol. Biol. 23, 327334.
Harris, N. L., Watt, V., Ronchese, F., and Le Gros, G. (2002). Differential T cell function and fate in lymph node and nonlymphoid tissues. J. Exp. Med. 195, 317326.
Im, G. I., and Han, J. D. (2001). Suppressive effects of interleukin-4 and interleukin-10 on the production of proinflammatory cytokines induced by titanium-alloy particles. J. Biomed. Mater. Res. 58, 531536.[CrossRef][ISI][Medline]
Lambert, A. L., Dong, W., Selgrade, M. K., and Gilmour, M. I. (2000). Enhanced allergic sensitization by residual oil fly ash particles is mediated by soluble metal constituents. Toxicol. Appl. Pharmacol. 165, 8493.[CrossRef][ISI][Medline]
Lambert, A. L., Dong, W., Winsett, D. W., Selgrade, M. K., and Gilmour, M. I. (1999). Residual oil fly ash exposure enhances allergic sensitization to house dust mite. Toxicol. Appl. Pharmacol. 158, 269277.[CrossRef][ISI][Medline]
Lambert, A. L., Selgrade, M. K., Winsett, D. W., and Gilmour, M. I. (2001). TNF-alpha enhanced allergic sensitization to house dust mite in brown Norway rats. Exp. Lung Res. 27, 617635.[CrossRef][ISI][Medline]
Lambrecht, B. N., and Hammad, H. (2003). Taking our breath away: Dendritic cells in the pathogenesis of asthma. Nat. Rev. Immunol. 3, 9941003.[CrossRef][ISI][Medline]
Li, N., Hao, M., Phalen, R. F., Hinds, W. C., and Nel, A. E. (2003). Particulate air pollutants and asthma. A paradigm for the role of oxidative stress in PM-induced adverse health effects. Clin. Immunol. 109, 250265.[CrossRef][ISI][Medline]
Li, N., Sioutas, C., Cho, A., Schmitz, D., Misra, C., Sempf, J., Wang, M., Oberley, T., Froines, J., and Nel, A. (2003). Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage. Environ. Health Perspect. 111, 455460.[ISI][Medline]
Nilsen, A., Hagemann, R., and Eide, I. (1997). The adjuvant activity of diesel exhaust particles and carbon black on systemic IgE production to ovalbumin in mice after intranasal instillation. Toxicology 124, 225232.[CrossRef][ISI][Medline]
Nygaard, U. C., Samuelsen, M., Aase, A., and Lovik, M. (2004). The capacity of particles to increase allergic sensitization is predicted by particle number and surface area, not by particle mass. Toxicol. Sci. 82, 515524.
Peterson, B., and Saxon, A. (1996). Global increases in allergic respiratory disease: The possible role of diesel exhaust particles. Ann. Allergy Asthma Immunol. 77, 263268; quiz 269270.[ISI][Medline]
Popp, W., Zwick, H., Steyrer, K., Rauscher, H., and Wanke, T. (1989). Sensitization to aeroallergens depends on environmental factors. Allergy 44, 572575.[ISI][Medline]
Salvi, S. (2001). Pollution and allergic airways disease. Curr. Opin. Allergy Clin. Immunol. 1, 3541.[CrossRef][Medline]
Saxon, A., and Diaz-Sanchez, D. (2005). Air pollution and allergy: You are what you breathe. Nat. Immunol. 6, 223226.[CrossRef][ISI][Medline]
Soukup, J. M., and Becker, S. (2001). Human alveolar macrophage responses to air pollution particulates are associated with insoluble components of coarse material, including particulate endotoxin. Toxicol. Appl. Pharmacol. 171, 2026.[CrossRef][ISI][Medline]
Steerenberg, P. A., Withagen, C. E., Dormans, J. A., Van Dalen, W. J., Van Loveren, H., and Casee, F. R. (2003). Adjuvant activity of various diesel exhaust and ambient particles in two allergic models. J. Toxicol. Environ. Health A 66, 14211440.[CrossRef][ISI][Medline]
Stringer, B., Imrich, A., and Kobzik, L. (1995). Flow cytometric assay of lung macrophage uptake of environmental particulates. Cytometry 20, 2332.[CrossRef][ISI][Medline]
Takafuji, S., Suzuki, S., Koizumi, K., Tadokoro, K., Miyamoto, T., Ikemori, R., and Muranaka, M. (1987). Diesel-exhaust particulates inoculated by the intranasal route have an adjuvant activity for IgE production in mice. J. Allergy Clin. Immunol. 79, 639645.[CrossRef][ISI][Medline]
Takano, H., Yoshikawa, T., Ichinose, T., Miyabara, Y., Imaoka, K., and Sagai, M. (1997). Diesel exhaust particles enhance antigen-induced airway inflammation and local cytokine expression in mice. Am. J. Respir. Crit. Care Med. 156, 3642.
Tao, F., Gonzalez-Flecha, B., and Kobzik, L. (2003). Reactive oxygen species in pulmonary inflammation by ambient particulates. Free Radic. Biol. Med. 35, 327340.[CrossRef][ISI][Medline]
Tao, F., and Kobzik, L. (2002). Lung macrophage-epithelial cell interactions amplify particle-mediated cytokine release. Am. J. Respir. Cell Mol. Biol. 26, 499505.
van Rijt, L. S., Prins, J. B., Leenen, P. J., Thielemans, K., de Vries, V. C., Hoogsteden, H. C., and Lambrecht, B. N. (2002). Allergen-induced accumulation of airway dendritic cells is supported by an increase in CD31(hi)Ly-6C(neg) bone marrow precursors in a mouse model of asthma. Blood 100, 36633671.
van Zijverden, M., de Haar, C., van Beelen, A., van Loveren, H., Penninks, A., and Pieters, R. (2001). Coadministration of antigen and particles optimally stimulates the immune response in an intranasal administration model in mice. Toxicol. Appl. Pharmacol. 177, 174178.[CrossRef][ISI][Medline]
Vermaelen, K. Y., Carro-Muino, I., Lambrecht, B. N., and Pauwels, R. A. (2001). Specific migratory dendritic cells rapidly transport antigen from the airways to the thoracic lymph nodes. J. Exp. Med. 193, 5160.[CrossRef][ISI][Medline]
Whitekus, M. J., Li, N., Zhang, M., Wang, M., Horwitz, M. A., Nelson, S. K., Horwitz, L. D., Brechun, N., Diaz-Sanchez, D., and Nel, A. E. (2002). Thiol antioxidants inhibit the adjuvant effects of aerosolized diesel exhaust particles in a murine model for ovalbumin sensitization. J. Immunol. 168, 25602567.
Yanagisawa, R., Takano, H., Inoue, K., Ichinose, T., Sadakane, K., Yoshino, S., Yamaki, K., Kumagai, Y., Uchiyama, K., Yoshikawa, T., and Morita, M. (2003). Enhancement of acute lung injury related to bacterial endotoxin by components of diesel exhaust particles. Thorax 58, 605612.
Yang, X., Wang, S., Fan, Y., and Han, X. (2000). IL-10 deficiency prevents IL-5 overproduction and eosinophilic inflammation in a murine model of asthma-like reaction. Eur. J. Immunol. 30, 382391.[CrossRef][ISI][Medline]
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