In vivo nasal challenge with diesel exhaust particles enhances expression of the CC chemokines rantes, MIP-1alpha, and MCP-3 in humans

Cellular basis of the role of diesel exhaust particles in inducing Th2-dominant response

There is growing evidence that diesel exhaust particles (DEP) can induce allergic diseases with increased IgE production and preferential activation of Th2 cells. To clarify the cellular basis of the role of DEP in the induction of Th2-dominant responses, we examined the effects of DEP on the cytokine production by T cells stimulated with anti-CD3/CD28 Ab and on that by monocyte-derived dendritic cells (MoDCs) stimulated with CD40L and/or IFN-gamma. We examined IFN-gamma, IL-4, IL-5, IL-8, and IL-10 produced by T cells and TNF-alpha, IL-1beta, IL-10, and IL-12 produced by MoDCs using real-time PCR analysis or by ELISA. To highlight the effects of DEP, we compared the effects of DEP with those of dexamethasone (DEX) and cyclosporin A (CyA). DEP significantly suppressed IFN-gamma mRNA expression and protein production, while it did not affect IL-4 or IL-5 mRNA expression or protein production. The suppressive effect on IFN-gamma mRNA expression was more potent than that of DEX and comparable at 30 mug/ml with 10(-7) M CyA. The suppressive effect on IFN-gamma production was also more potent than that of either DEX or CyA. DEP suppressed IL-12p40 and IL-12p35 mRNA expression and IL-12p40 and IL-12p70 production by MoDCs, while it augmented IL-1beta mRNA expression. Finally, by using a thiol antioxidant, N-acetyl cysteine, we found that the suppression of IFN-gamma production by DEP-treated T cells was mediated by oxidative stress. These data revealed a unique characteristic of DEP, namely that they induce a Th2 cytokine milieu in both T cells and dendritic cells.

Activation of the aryl hydrocarbon receptor increases pulmonary neutrophilia and diminishes host resistance to influenza A virus

Unlike their role in bacterial infection, less is known about the role of neutrophils during pulmonary viral infection. Exposure to pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) results in excess neutrophils in the lungs of mice infected with influenza A virus. TCDD is the most potent agonist for the aryl hydrocarbon receptor (AhR), and exposure to AhR ligands has been correlated with exacerbated inflammatory lung diseases. However, knowledge of the effects of AhR agonists on neutrophils is limited. Likewise, the factors regulating neutrophil responses during respiratory viral infections are not well characterized. To address these knowledge gaps, we determined the in vivo levels of KC, MIP-1alpha, MIP-2, LIX, IL-6, and C5a in infected mouse lungs. Our data show that these neutrophil chemoattractants are generally produced transiently in the lung within 12-24 h of infection. We also report that expression of CD11a, CD11b, CD49d, CD31, and CD38 is increased on pulmonary neutrophils in response to influenza virus. Using AhR-deficient mice, we demonstrate that excess neutrophilia in the lung is mediated by activation of the AhR and that this enhanced neutrophilia correlates directly with decreased survival in TCDD-exposed mice. Although AhR activation results in more neutrophils in the lungs, we show that this is not mediated by deregulation in levels of common neutrophil chemoattractants, expression of adhesion molecules on pulmonary neutrophils, or delayed death of neutrophils. Likewise, exposure to TCDD did not enhance pulmonary neutrophil function. This study provides an important first step in elucidating the mechanisms by which AhR agonists exacerbate pulmonary inflammatory responses.

Biology of diesel exhaust effects on respiratory function

In recent decades, clinicians and scientists have witnessed a significant increase in the prevalence of allergic rhinitis and asthma. The factors underlying this phenomenon are clearly complex; however, this rapid increase in the burden of atopic disease has undeniably occurred in parallel with rapid industrialization and urbanization in many parts of the world. Consequently, more people are exposed to air pollutants than at any point in human history. Worldwide, increases in allergic respiratory disease have mainly been observed in urban communities. Epidemiologic and clinical investigations have suggested a strong link between particulate air pollution and detrimental health effects, including cardiopulmonary morbidity and mortality. The purpose of this review is to provide an evidence-based summary of the health effects of air pollutants on asthma, focusing on diesel exhaust particles (DEPs) as a model particulate air pollutant. An overview of observational and experimental studies linking DEPs and asthma will be provided, followed by consideration of the mechanisms underlying DEP-induced inflammation and a brief discussion of future research and clinical directions.

Determination of selected polycyclic aromatic hydrocarbons and oxygenated polycyclic aromatic hydrocarbons in aerosol samples by high-performance liquid chromatography and liquid chromatography?tandem mass spectrometry

Fine and ultrafine particles are probably responsible for numerous health effects, but it is still unclear whether and to what extent the particle itself or organic compounds adsorbed or condensed on the particle are responsible for the effects observed. One important class of particle-bound substances are the polycyclic aromatic hydrocarbons (PAH) and their oxygenated derivatives. To improve the tools used for chemical characterization of particulate matter analytical methods for the determination of PAH and oxygenated PAH in aerosol samples of different origin have been developed and optimized. PAH on high-volume filters and on soot aerosols were analyzed by using accelerated solvent extraction for extraction and high-performance liquid chromatography with fluorescence detection for separation and quantification. Total PAH concentrations were in the range 0.3-9.3 ng m(-3). For analysis of selected oxygenated PAH on high-volume filters a liquid chromatography-tandem mass spectrometric method was developed and optimized. Preliminary investigations showed that oxygenated PAH at pg m(-3) concentrations can be determined.

Diesel exhaust-associated gas components enhance chemokine production by cervical lymph-node cells from mice immunized with sugi basic proteins

Previously, we showed that exposure to diesel exhaust (DE) increased inflammatory cells in the airway and cytokine production from local lymph-node cells after antigen stimulation. To clarify the role of particle-free diesel gas components in induction of allergic inflammation, we compared the effect of DE and gas components on pollen-antigen-stimulated chemokine production by cervical lymph nodes (CLN) cells in BALB/c mice. Groups of mice were exposed to 0 (control), 1.0 mg diesel exhaust particles (DEP)/m(3) (DE), or filtered 1.0 mg DEP/m(3) DE (gas) for 12 h daily for 5 wk. Each group of mice was injected intraperitoneally with sugi basic protein (SBP), a major allergen of Japanese cedar pollen, immediately before their exposure to DE or gas. On days 14 and 35, each mouse received an additional SBP intranasally. Exposure to DE or gas did not affect the lymphocyte subpopulations of CLN. Culture supernatants of CLN cells from DE-exposed, SBP-immunized mice had significantly increased levels of monocyte chemoattractant protein-1. Exposure to gas significantly increased the amount of thymus- and activation-regulated chemokine and macrophage inflammatory proteins-1 alpha in the CLN cells from SBP-immunized mice. These results suggest that Gas components as well as DEP may differentially regulate production of chemokines at local sites.

Cytokine expression in allergic inflammation: systematic review of in vivo challenge studies

BACKGROUND

Allergic inflammatory responses are driven by cells of the immune system that rely on cytokines to regulate the activity of other immune and structural cells.

OBJECTIVE

To review published studies to (1) identify cytokines consistently increased after allergen challenge in atopic patients and (2) investigate temporal variation in cytokine expression.

METHODS

A PUBMED systematic search was used to extract data from studies involving analysis of cytokine expression in fluids or biopsies following in vivo allergen challenge in atopic patients.

RESULTS

Data were extracted from 82 studies. There were no consistent reports of cytokine protein increase in fluids of patients at 0-1 h after challenge. At 4-12 h, the chemokines eotaxin, macrophage inflammatory protein-1alpha, RANTES (regulated on activation normal T cell expressed and secreted) and interleukin (IL)-8 have all been consistently reported to be up-regulated. At 18-24 h after challenge, the lymphokines IL-4, IL-5 and IL-13, as well as the pro-inflammatory cytokines granulocyte-macrophage colony-stimulating factor, tumour necrosis factor-alpha and IL-6 are consistently increased when compared with the respective control value. There were no reports of up-regulation in interferon-gamma protein and mRNA and in IL-2 mRNA.

CONCLUSION

The expression of granulocyte-macrophage colony-stimulating factor is consistently increased in tissues at 4-12 h after challenge. The influence of this cytokine on antigen capture and presentation by dendritic cells should be further investigated. Additionally, allergen challenge studies are needed that investigate the expression of macrophage-derived chemokine and thymus-regulated and activation-regulated chemokine in tissues of atopic patients. Blocking the effects of these lymphocyte-specific chemokines might provide new therapeutic approaches for the control of allergic inflammation.

A review of experimental studies on diesel exhaust particles and nasal epithelium alterations

The aim of the present review is to summarize biological events in nasal epithelium after short-term exposure to diesel exhaust particles (DEP). Therefore human, animal, and in vitro studies carried out since 1987 are reviewed. Short-term exposure results included qualitative alterations characterized by immediate nasal hyperresponsiveness, antioxidant responses, marked epithelial inflammation, and a specific humoral response. In addition, studies on combined DEP/allergen challenge reported that, besides their intrinsic deleterious properties, DEP produced adjuvant-like effects on the immediate and late-phase response to allergen challenge, since they are able to mimic effects occurring after allergen challenge. DEP act deeply in nasal epithelium by (1) directing cytokine gene expression toward a Th2 profile, (2) enhancing local antigen-specific immunoglobulin E (IgE) production, and (3) driving in vivo isotype switch to IgE. Furthermore, DEP can induce in allergic subjects sensitization to a neoallergen, sensitization that did not occur with exposure to the neoantigen alone. Particulate pollutants such as DEP, encountered in urban areas, are therefore thought to be contributing causal factors to the exaggerated sensitization to allergens in subjects with appropriate genetic predisposition, sensitization that they might not otherwise have experienced. These findings add weight to the hypothesis that DEP are involved in the increased prevalence of airway allergic diseases.

Particulate air pollutants and asthma. A paradigm for the role of oxidative stress in PM-induced adverse health effects

Asthma is a chronic inflammatory disease, which involves a variety of different mediators, including reactive oxygen species. There is growing awareness that particulate pollutants act as adjuvants during allergic sensitization and can also induce acute asthma exacerbations. In this communication we review the role of oxidative stress in asthma, with an emphasis on the pro-oxidative effects of diesel exhaust particles and their chemicals in the respiratory tract. We review the biology of oxidative stress, including protective and injurious effects that explain the impact of particulate matter-induced oxidative stress in asthma.

Effect of glutathione-S-transferase M1 and P1 genotypes on xenobiotic enhancement of allergic responses: randomised, placebo-controlled crossover study

BACKGROUND

Particulate pollution is associated with the occurrence of asthma and allergy. The model pollutant, diesel exhaust particles, can participate with allergens in starting and exacerbating allergic airway diseases in part by production of reactive oxygen species. Glutathione-S-transferases (GSTs) can metabolise reactive oxygen species and detoxify xenobiotics present in diesel exhaust particles. We tested the hypothesis that null genotypes for GSTM1 and GSTT1, and GSTP1 codon 105 variants (I105 and V105) are key regulators of the adjuvant effects of diesel exhaust particles on allergic responses.

METHODS

Patients sensitive to the ragweed allergen were challenged intranasally with allergen alone and with allergen plus diesel exhaust particles in a randomised order at separate visits. Nasal allergen-specific IgE, histamine, interleukin 4, and interferon gamma concentrations were measured before and 24 h after challenge.

FINDINGS

Individuals with GSTM1 null or the GSTP1 I105 wildtype genotypes showed enhanced nasal allergic responses in the presence of diesel exhaust particles. Compared with patients with a functional GSTM1 genotype, GSTM1 null patients had a significantly larger increase in IgE (median 102.5 U/mL [range 1.0-510.5] vs 45.5 U/mL [1.5-60.6], p=0.03) and histamine (14.0 nmol/L [-0.2-24.7] vs 7.4 nmol/L [1.2-12.3], p=0.02) after diesel exhaust particles plus allergen challenge. The I105 GSTP1 genotype was associated with an increase in IgE (120.3 U/mL [6.7-510.5] vs 27.7 U/mL [-1.5-60.6], p=0.03) and histamine (13.8 nmol/L [3.1-24.7] vs 5.2 nmol/L [-0.2-19.6], p=0.01) after challenge with diesel exhaust particles and allergens. The diesel exhaust particles enhancement was largest in patients with both the GSTM1 null and GSTP1 I/I genotypes.

INTERPRETATION

GSTM1 and GSTP1 modify the adjuvant effect of diesel exhaust particles on allergic inflammation.

Diesel exhaust particles exert acute effects on airway inflammation and function in murine allergen provocation models

BACKGROUND

Epidemiologic studies show that sudden surges in ambient particulate matter (PM) levels can trigger acute asthma exacerbations. Although diesel exhaust particles (DEPs) act as an adjuvant for allergic sensitization, this is a delayed response and does not explain acute PM effects on airway hyperreactivity (AHR).

OBJECTIVE

Our aim was to determine the acute effects of DEPs on AHR using a mouse model.

METHODS

Three protocols were developed, 2 of which require OVA sensitization, whereas the third was OVA independent. In the mild sensitization protocol BALB/c mice receive intraperitoneal OVA without alum and are then challenged with aerosolized OVA with or without DEPs. In the postchallenge model DEPs are delivered after OVA challenge to animals sensitized by intraperitoneal OVA plus alum. In the third protocol nebulizer DEPs were also delivered to IL-5-overexpressing mice that exhibit constitutive airway inflammation. Animals were subjected to whole-body plethysmography (WBP) and then killed for performance of bronchoalveolar lavage, histology, and serology.

RESULTS

DEP delivery concomitant with OVA challenge or after the induction of airway inflammation with this allergen induced increased AHR in models 1 and 2, respectively. Although these animals showed DEP-induced inflammation and mucus production in the intermediary airways, there was no effect on OVA-specific IgE or T(H)2 cytokine production. In the IL-5 transgenic mice it was possible to induce similar effects with DEPs in the absence of an allergen.

CONCLUSION

We demonstrate that DEPs induced AHR independent of their adjuvant effects, suggesting the use of these models to study the mechanism or mechanisms of acute asthma exacerbation by means of PM.

The diesel exhaust component pyrene induces expression of IL-8 but not of eotaxin

Environmental pollutants can influence the expression of immunoregulatory molecules and, in this way, promote allergies. The local synthesis of proinflammatory chemokines is an important aspect in the development of allergic airway inflammation. We have characterized the influence of pyrene, a polycyclic aromatic hydrocarbon (PAH) contained, for example, in diesel exhaust particles (DEP), on transcription and secretion of the chemokines interleukin-8 (IL-8) and eotaxin. Reporter genes under control of the respective promoters were tested in the human cell lines A549 and HeLa, mRNA production was assayed in A549 cells and protein production was measured by ELISA in cell supernatants from primary human fibroblasts. Pyrene content of cell supernatants was measured by analytical HPLC. Promoter activity, mRNA production and protein expression of IL-8 were increased by pyrene. The activating effect in reporter gene studies was abolished by mutating either an NF-kappaB or an AP-1 binding site in the IL-8 promoter. In contrast, pyrene showed no effect on transcription from the eotaxin promoter, despite the important role of this chemokine in asthma. Our data show that pyrene has specific effects on chemokine synthesis, which are not restricted to mediators primarily associated with atopic diseases. Pyrene also affected cells not derived from lung tissue, which suggests a broader immunoregulatory influence for this pollutant.

Use of proteomics to demonstrate a hierarchical oxidative stress response to diesel exhaust particle chemicals in a macrophage cell line

Epidemiological studies demonstrate an association between short term exposure to ambient particulate matter (PM) and cardiorespiratory morbidity and mortality. Although the biological mechanisms of these adverse effects are unknown, emerging data suggest a key role for oxidative stress. Ambient PM and diesel exhaust particles (DEP) contain redox cycling organic chemicals that induce pro-oxidative and pro-inflammatory effects in the lung. These responses are suppressed by N-acetylcysteine (NAC), which directly complexes to electrophilic DEP chemicals and exert additional antioxidant effects at the cellular level. A proteomics approach was used to study DEP-induced responses in the macrophage cell line, RAW 264.7. We demonstrate that in the dose range 10-100 microg/ml, organic DEP extracts induce a progressive decline in the cellular GSH/GSSG ratio, in parallel with a linear increase in newly expressed proteins on the two-dimensional gel. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry and electrospray ionization-liquid chromatography/mass spectrometry/mass spectrometry analysis, 32 newly induced/NAC-suppressed proteins were identified. These include antioxidant enzymes (e.g. heme oxygenase-1 and catalase), pro-inflammatory components (e.g. p38MAPK and Rel A), and products of intermediary metabolism that are regulated by oxidative stress. Heme oxygenase-1 was induced at low extract dose and with minimal decline in the GSH/GSSG ratio, whereas MAP kinase activation required a higher chemical dose and incremental levels of oxidative stress. Moreover, at extract doses >50 microg/ml, there is a steep decline in cellular viability. These data suggest that DEP induce a hierarchical oxidative stress response in which some of these proteins may serve as markers for oxidative stress during PM exposures.

Adjuvant activity of various diesel exhaust and ambient particles in two allergic models

In the framework of an EU study entitled "Respiratory Allergy and Inflammation Due to Ambient Particles" (RAIAP), various collected particulate matter samples were to be tested for their adjuvant potency in two animal models of allergy. A pollen allergy model in the Brown Norway (BN) rat and an ovalbumin model in the BALB/c mouse were used in this study to compare the discriminatory value of these two models and to evaluate them for later studies of collected RAIAP-samples. Two different sources of diesel exhaust particles (DEP I and DEP II ), a residual oil fly ash source (ROFA), and two sources of ambient particles (Ottawa dust, EHC-93, and road tunnel dust, RTD) were tested. Rats were sensitized intratracheally with Timothy grass pollen (Phleum pratense, 200 microl, 10 mg/ml) on d 0, challenged on d 21, and examined on d 25. Mice were sensitized intranasally at d 0 and 14, challenged intranasally at d 35, 38, and 41 (50 microl, 0.4 mg ovalbumin/ml), and examined at d 42. Particulate matter (PM) was administered either during the sensitization phase only or during the sensitization and challenge phases (for mice only) or during the challenge phase only. In the pollen model, only DEP I, but not DEP II, ROFA, EHC-93, and RTD, stimulated the immunoglobulin (Ig) E and IgG1 response in serum to pollen allergens. In addition to this adjuvant effect noted, no other biomarkers in lung or bronchoalveolar lavage (BAL) revealed adjuvant activity in the pollen model. In the BAL of BN rats exposed to a combination of pollen and PM, the percentages of eosinophilic granulocytes were decreased compared to the BAL of BN rats immunized with pollen only. In the ovalbumin model, the IgE levels in serum were increased in mice after coexposure to ovalbumin and PM (including DEPI, DEPII, ROFA, EHC-93, and RTD) in the sensitization phase but not after coexposure during the challenge phase only. The inflammatory response was greater in the lung, predominantly the influx of eosinophilic granulocytes, as was observed by both histopathological examination and BAL analysis. In addition, BAL levels of inflammatory interleukin (IL)-4 were increased. Based on the IgE antibody response to ovalbumin, the ovalbumin model ranked the adjuvant capacity of the particles in the following order: RTD > ROFA > EHC-93 > DEPI > DEPII. In conclusion, the ovalbumin model is a sensitive system to detect adjuvant activity of airborne particles, whereas the pollen-induced allergy model in rat was less sensitive.

Effect of diesel on chemokines and chemokine receptors involved in helper T cell type 1/type 2 recruitment in patients with asthma

The objective of this study was to evaluate if diesel exhausts could favor helper T cell type (Th) 2-associated allergic reactions either through an increased production of Th2-associated chemokines and of their associated receptors or through a decrease of Th1-attracting chemokines and chemokine receptors. Diesel but not allergen exposure of peripheral blood mononuclear cells from subjects with allergy induced a release of I-309, whereas both diesel and Der p 1 induced an early but transient release of monokine induced by IFN-gamma and a late release of pulmonary and activation-regulated chemokine. Although both Th1- and Th2-attracting chemokines were induced, the resulting effect was an increased chemotactic activity on Th2 but not Th1 cells. Surprisingly, diesel induced a late increase in the expression of the Th1-associated CXC receptor 3 and CC receptor 5. T cell CXC receptor 3 upregulation was not associated with an increased migration to its ligands. These two antagonistic effects have been previously reported as a scavenger mechanism to clear chemokines. Altogether, these results suggest that diesel, even without allergen, may amplify a type 2 immune response but that it can also increase late Th1-associated chemokine receptor expression, perhaps as a scavenger mechanism to clear pro-Th1 chemokines and promote the Th2 pathway.

Differences in airway-inflammation development by house dust mite and diesel exhaust inhalation among mouse strains

Three mouse strains (BALB/c, ICR, and C3H/He) were injected intratracheally with house dust mites (Der f) four times at 2-week intervals during exposure to diesel exhaust (DE) or clean air for 8 weeks. Der f treatment caused eosinophilic inflammation and proliferation of goblet cells in the airways of the three strains. DE + Der f caused a further increase of eosinophils in BALB/c and ICR mice, but not in C3H/He mice. DE + Der f significantly increased interleukin (IL)-5; regulated on activation, normal T cell expressed, and presumably secreted (RANTES); eotaxin, monocyte chemotactic protein-1 (MCP-1); and macrophage-inflammatory protein-1 alpha (MIP-1 alpha) in all three strains. However, the protein of IL-5 decreased more in C3H/He mice treated with DE + Der f than in mice treated with Air + Der f. The levels of IL-5 in lung tissues corresponded to the pathological changes by Der f and/or DE treatment. The levels of MCP-1 and MIP-1 alpha in the three strains corresponded to the accumulation of lymphocytes in the airway. The adjuvant effect of DE on IgG1 production was observed in the ICR and C3H/He mice. These results suggest that the murine strain differences in the production of eosinophilic airway inflammation by DE + Der f is related to differences in local expression of IL-5, eotaxin, and IgG1 production. The enhancing effects of DE exposure may be mediated mainly by local IL-5.

Effects of low-toxicity particulate matter on human nasal function

Chronic nasal and paranasal sinus problems affect approximately 15% of the population in industrialized countries. Recent studies suggest that particulate matter might contribute to this condition. The effects of acute exposure to low-toxicity particulate matter on human nasal airflow, mucociliary transport, and nasal discomfort should be assessed. Thirty-two healthy volunteers were exposed to 0 (control), 500, 1000, and 5000 micrograms/m3 calcium carbonate dust for 3 hours and nasal saccharin transport time (STT), rhinomanometry, and visual analog scales (VAS) on nasal discomfort were obtained. A dose dependent decrease of STT (P = 0.02) and nasal patency (P = 0.04), and increased sensation of nasal obstruction (P = 0.002) and dryness (P = 0.03) was observed. The results indicate that acute exposure to low-toxicity particulate matter in concentrations frequently encountered in western agglomeration areas may affect nasal functions and cause nasal symptoms.

Influences on the development of allergy and asthma

A number of factors contribute to development of asthma and allergy in humans. Genetic factors clearly play a role in development of asthma and allergy. However, recent studies suggest that westernized lifestyle, perhaps certain pollutants, and less frequent exposure to microbes may allow for allergy to develop. It is the interactions of risk genes with urbanized environments that lead to development of allergy. Recent studies suggest that the most significant period of development of allergy is in early childhood, with additional data suggesting that a tendency for mononuclear cells to produce Th2 cytokines exists in early childhood. Reviewed in this article are genetic, inflammatory and lifestyle factors which contribute to development of allergy in childhood.

Enhancement of antigen-induced eosinophilic inflammation in the airways of mast-cell deficient mice by diesel exhaust particles

The present study was conducted to clarify the involvement of mast cells in the exacerbating effect of diesel exhaust particles (DEP) toward allergic airway inflammation and airway hyperresponsiveness (AHR). Airway inflammation by the infiltration of cosinophils with goblet cell proliferation and AHR, as well as by the production of antigen-specific IgG1 and IgE, in plasma were examined using mast cell-deficient mice (W/W(v)) and normal mice (W/W(+)). Both groups of mice received ovalbumin (OVA) or OVA+DEP intratracheally. The eosinophilic airway inflammation and goblet cell proliferation promoted by OVA were significantly greater in W/W(+) than in W/W(v). A similar result was observed in AHR, but was not significant among both groups of mice. DEP enhanced OVA induced-allergic airway inflammation, goblet cell proliferation, and development of AHR in W/W(v), but not in W/W(+). DEP decreased production of antigen-specific IgG1 and IgE in both groups of mice. Mast cells were observed in the submucosal layer of the main bronchus in W/W(v). The number of mast cells was significantly decreased by OVA treatment. The results indicate that mast cells are not necessary to enhance airway damage and development of AHR in W/W(v) by DEP. However, mast cells may be required for the OVA-induced cosinophilic inflammation, airway damage with goblet cell proliferation, and AHR in W/W(+).

Comparison of the pro-oxidative and proinflammatory effects of organic diesel exhaust particle chemicals in bronchial epithelial cells and macrophages

Inhaled diesel exhaust particles (DEP) exert proinflammatory effects in the respiratory tract. This effect is related to the particle content of redox cycling chemicals and is involved in the adjuvant effects of DEP in atopic sensitization. We demonstrate that organic chemicals extracted from DEP induce oxidative stress in normal and transformed bronchial epithelial cells, leading to the expression of heme oxygenase 1, activation of the c-Jun N-terminal kinase cascade, IL-8 production, as well as induction of cytotoxicity. Among these effects, heme oxygenase 1 expression is the most sensitive marker for oxidative stress, while c-Jun N-terminal kinase activation and induction of apoptosis-necrosis require incremental amounts of the organic chemicals and increased levels of oxidative stress. While a macrophage cell line (THP-1) responded in similar fashion, epithelial cells produced more superoxide radicals and were more susceptible to cytotoxic effects than macrophages. Cytotoxicity is the result of mitochondrial damage, which manifests as ultramicroscopic changes in organelle morphology, a decrease in the mitochondrial membrane potential, superoxide production, and ATP depletion. Epithelial cells also differ from macrophages in not being protected by a thiol antioxidant, N-acetylcysteine, which effectively protects macrophages against cytotoxic DEP chemicals. These findings show that epithelial cells exhibit a hierarchical oxidative stress response that differs from that of macrophages by more rapid transition from cytoprotective to cytotoxic responses. Moreover, epithelial cells are not able to convert N-acetylcysteine to cytoprotective glutathione.

Size fractions of ambient particulate matter induce granulocyte macrophage colony-stimulating factor in human bronchial epithelial cells by mitogen-activated protein kinase pathways

Environmental pollutants, including ambient particulate matter (PM), increase respiratory morbidity. Studies of model PM particles, including residual oil fly ash and freshly generated diesel exhaust particles, have demonstrated that PM affects inflammatory airway responses. Neither of these particles completely represents ambient PM, and therefore questions remain about ambient particulates. We hypothesized that ambient PM of different size fractions collected from an urban environment (New York City air), would activate primary culture human bronchial epithelial cells (HBECs). Because of the importance of granulocyte-macrophage colony-stimulating factor (GM-CSF) on inflammatory and immunomodulatory processes, we focused our studies on this cytokine. We demonstrated that the smallest size fraction (ultrafine/fine; < 0.18 micro m) of ambient PM (11 micro g/cm(2)), upregulated GM-CSF production (2-fold increase). The absence of effect of carbon particles of similar size, and the day-to-day variation in response, suggested that the chemical composition, but not the particle itself, was necessary for GM-CSF induction. Activation of the extracellular signal-regulated kinase and the p38 mitogen-activated protein kinase was associated with, and necessary for, GM-CSF release. These studies serve to corroborate and extend those on model particles. Moreover, they emphasize the role of the smallest size ambient particles in airway epithelial cell responses.

Diesel exposure favors Th2 cell recruitment by mononuclear cells and alveolar macrophages from allergic patients by differentially regulating macrophage-derived chemokine and IFN-gamma-induced protein-10 production

Diesel exhausts and their associated organic compounds may be involved in the recent increase in the prevalence of allergic disorders, through their ability to favor a type 2 immune response. Type 2 T cells have been shown to be preferentially recruited by the chemokines eotaxin (CCL11), macrophage-derived chemokine (MDC, CCL22), and thymus activation-regulated chemokine (CCL17) through their interaction with CCR3 and CCR4, respectively, whereas type 1 T cells are mainly recruited by IFN-gamma-induced protein-10 (CXCL10) through CXCR3 binding. The aim of the study was to evaluate the effect of diesel exposure on the expression of chemokines involved in type 1 and 2 T cell recruitment. PBMC and alveolar macrophages from house dust mite allergic patients were incubated with combinations of diesel extracts and Der p 1 allergen, and chemokine production was analyzed. Diesel exposure alone decreased the constitutive IP-10 production, while it further augmented allergen-induced MDC production, resulting in a significantly increased capacity to chemoattract human Th2, but not Th1 clones. Inhibition experiments with anti-type 1 or type 2 cytokine Abs as well as cytokine mRNA kinetic evaluation showed that the chemokine variations were not dependent upon IL-4, IL-13, or IFN-gamma expression. In contrast, inhibition of the B7:CD28 pathway using a CTLA-4-Ig fusion protein completely inhibited diesel-dependent increase of allergen-induced MDC production. This inhibition was mainly dependent upon the CD86 pathway and to a lesser extent upon the CD80 pathway. These results suggest that the exposure to diesel exhausts and allergen may likely amplify a deleterious type 2 immune response via a differential regulation of chemokine production through the CD28 pathway.

Thiol antioxidants inhibit the adjuvant effects of aerosolized diesel exhaust particles in a murine model for ovalbumin sensitization

Although several epidemiological studies indicate a correlation between exposure to ambient particulate matter and adverse health effects in humans, there is still a fundamental lack of understanding of the mechanisms involved. We set out to test the hypothesis that reactive oxygen species are involved in the adjuvant effects of diesel exhaust particles (DEP) in a murine OVA sensitization model. First, we tested six different antioxidants, N-acetylcysteine (NAC), bucillamine (BUC), silibinin, luteolin, trolox (vitamin E), and ascorbic acid, for their ability to interfere in DEP-mediated oxidative stress in vitro. Of the six agents tested, only the thiol antioxidants, BUC and NAC, were effective at preventing a decrease in intracellular reduced glutathione:glutathione disulfide ratios, protecting cells from protein and lipid oxidation, and preventing heme oxygenase 1 expression. Therefore, we selected the thiol antioxidants for testing in the murine OVA inhalation sensitization model. Our data demonstrate that NAC and BUC effectively inhibited the adjuvant effects of DEP in the induction of OVA-specific IgE and IgG1 production. Furthermore, NAC and BUC prevented the generation of lipid peroxidation and protein oxidation in the lungs of OVA- plus DEP-exposed animals. These findings indicate that NAC and BUC are capable of preventing the adjuvant effects of inhaled DEP and suggest that oxidative stress is a key mechanistic component in the adjuvant effect of DEP. Antioxidant treatment strategies may therefore serve to alleviate allergic inflammation and may provide a rational basis for treating the contribution of particulate matter to asthmatic disease.

Induction of inflammatory response of mice exposed to diesel exhaust is modulated by CD4(+) and CD8(+) T cells

Exposure to diesel exhaust (DE) increased airway inflammatory responses and airway responsiveness to allergen challenge. To clarify the roles of T cells in DE exposure-induced early inflammation, we studied the effect of CD4 and CD8 cells on the effect DE might have on allergic inflammation by using monoclonal antibody-mediated cellular depletion assays. In the bronchoalveolar lavage (BAL) fluid, the numbers of inflammatory cells from 3 mg/m(3) DE-exposed and ovalbumin (OVA)-immunized mice markedly increased. Depletion of CD4(+) cells resulted in reduced accumulation of inflammatory cells. DE exposure to OVA-immunized mice significantly increased interleukin (IL)-1 beta production but decreased IL-12 production. DE exposure significantly enhanced production of the macrophage inflammatory proteins (MIP)-1 alpha and MIP-2, but not monocyte chemoattractant protein (MCP)-1 and regulated upon activation normal T cells expressed and secreted (RANTES). Treatment with anti-CD4 and anti-CD8 mAbs abrogated the adverse effect of DE exposure. In CLN cells from OVA + DE-exposed mice, CD45R/B220-, CD3-, CD4-, and CD8-positive cells were significantly increased, but the OVA-stimulated cytokine production remained at the same levels with OVA-immunized mice. These findings suggest that the induction of early inflammatory responses by DE exposure may initially be related to the modulated function of lymphocyte subpopulations.