Doses Of Diesel Exhaust Particles Research Articles

ディーゼル排気粒子のＴｈ１／Ｔｈ２バランスおよびコラーゲン関節炎に及ぼす影響

The effects of diesel exhaust particles (DEP) on Th 1/Th 2 balance and collagen-induced arthritis (CIA) in mice were investigated. Oral administration of neither DEP nor the antigen hen egg lysozyme (HEL) alone produced the Th 1 cytokine IFN-γ and the Th 2 cytokine IL-4. DEP administered orally together with HEL increased the secretion of IFN-γ as well as IL-4 in a dose -related fashion, although IL-4 appeared to be more efficiently secreted in mice given lower doses of DEP. Similar results were obtained when anti-HEL IgG 2 a and IgG 1 antibodies which were Th 1 and Th 2 cell-dependently produced, respectively, were measured. Intraperitoneal injection of HEL alone induced marked Th 2 responses including anti-HEL IgG 1 and IL-4 production, while negligible induction of Th 1 responses including anti-HEL IgG 2 a and IFN-γ. were observed in mice injected with the antigen in the same manner. DEP plus HEL administered intraperitoneally further facilitated the Th 2 responses, but the Th 1 responses remained unchanged. HEL emulsified with complete Freund's adjuvant induced both the Th 1 and Th 2 responses. Furthermore, nasal administration of DEP led to the augmentation of CIA that was associated with anti-type II collagen IgG antibody production. Antigenspecific IgG 2 a and IgG 1 antibodies as well as IFN-γ and IL-4 were also markedly produced. Thus, DEP appear to modulate Th 1/Th 2 balance and have ability to influence autoim-mune diseases.

Sensitive and selective detection of urinary 1-nitropyrene metabolites following administration of a single intragastric dose of diesel exhaust particles (SRM 2975) to rats.

1-Nitropyrene (1-NP) has been proposed as a marker for exposure to diesel exhaust particles (DEP). Since the extent of the actual intake of 1-NP adsorbed on DEP will be relatively low, sensitive and selective methods are needed regarding human exposure assessment. Two analytical methods are presented for the assessment of 1-NP metabolites in urine of male Sprague-Dawley rats administered a single intragastric dose of native DEP (SRM 2975, 20 mg, 35.7 microgram of 1-NP/g). Enzymatically hydrolyzed urine was extracted using Blue Rayon. The extracts were analyzed directly, using HPLC with postcolumn on-line reduction and fluorescence detection (HPLC-Flu), or were processed further for GC/MS/MS analysis. Although sensitive to several metabolites, the HPLC-Flu method lacked selectivity for quantitation of some important metabolites in rat urinary extracts, and therefore seems suitable for screening purposes only. With regard to GC/MS/MS analysis, derivatization with heptafluorobutyrylimidazole (HFBI) yielded low limits of determination for hydroxy-1-aminopyrenes, hydroxy-N-acetyl-1-aminopyrenes (converted to derivatized hydroxy-1-aminopyrenes by the reagent), and 1-aminopyrene (1.8-9.2 fmol on the column). Derivatization of hydroxy-1-nitropyrenes yielded relatively high limits of determination, and therefore, hydroxy-1-nitropyrenes were reduced to hydroxy-1-aminopyrenes prior to derivatization with HFBI. Intragastric administration of DEP to rats resulted in urinary excretion of 6-hydroxy-N-acetyl-1-aminopyrene, 8-hydroxy-N-acetyl-1-aminopyrene, 6-hydroxy-1-nitropyrene, 8-hydroxy-1-nitropyrene, and 3-hydroxy-1-nitropyrene (7, 1.2, 1.6, 0.3, and 0.5% of the dose within 12 h, respectively). 1-Nitropyrene, N-acetyl-1-aminopyrene, and 3-, 6-, and 8-hydroxy-1-aminopyrene were not observed as urinary metabolites following administration of a single dose of DEP. The observed excretion pattern and urinary metabolite concentrations suggest that 1-NP present on unmodified DEP becomes bioavailable to a large extent and is metabolized in the same way as was previously observed following administration of pure 1-NP. The presented methods are promising for assessment of human exposure to 1-NP, e.g., following exposure to DEP, because of the possibility of analyzing large volumes of urine, the conversion of three types of metabolites to one (the amino metabolites), and the low detection limits that are achieved.

Diesel exhaust particles stimulate human airway epithelial cells to produce cytokines relevant to airway inflammation in vitro

Background: Epidemiologic and experimental studies suggest that air pollution such as diesel exhaust particles (DEPs), one of the important air pollutants, may play a role in the increasing prevalence of allergic airway diseases. Objective: We studied the effect of suspended particulate matter (SPM) and its main component, DEPs, on the production of IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) by human airway epithelial cells in vitro. Methods: SPM obtained from high-volume air samplers and DEPs were added to cultured human nasal polyp–derived upper airway, normal bronchial, and transformed bronchial epithelial cells. Production of GM-CSF and IL-8 by airway epithelial cells was evaluated. Results: Nontoxic doses of DEPs showed a significant stimulatory effect on IL-8 and GM-CSF production by these three kinds of epithelial cells in a dose- and time-dependent fashion. SPM had a stimulatory effect on GM-CSF, but not IL-8, production. These effects were abrogated by treatment with a protein synthesis inhibitor, cycloheximide, suggesting that the process required a de novo protein synthesis. On the double-chamber plates, airway epithelial cells responded to DEPs only when they were stimulated from the apical sides, which can be a model for in vivo environments. Neither charcoal nor graphite showed such stimulatory effects, indicating that the activity of DEPs did not derive from their particulate nature. Benzo(a)pyrene, one of the main aromatic hydrocarbons contained in DEPs, showed a stimulatory effect on the release of the cytokines, and this organic substance might have a causative effect on of the potency of DEPs. Conclusion: We conclude that SPM and DEPs, its main component, might be important air pollutants in the activation of airway epithelial cells for the release of cytokines relevant to allergic airway inflammation. (J Allergy Clin Immunol 1998;101:778-785.)

Diesel Exhaust Particles Induced Release of Interleukin 6 and 8 by (Primed) Human Bronchial Epithelial Cells (Beas 2b) In Vitro

Several epidemiological studies have recently shown associations of increased premature mortality rates with ambient paniculate air pollution. Diesel exhaust particles (DEP) may constitute an important part of (ultra)fine particulate air pollution in urban areas and may therefore contribute to its toxicity. Epithelial lining of the respiratory tract may be the first target of the toxic effects of DEP, that upon exposure may release pro-inflammatory mediators such as interleukin 6 and 8 (IL-6, IL-8), ultimately causing airway tissue damage and immune alterations. In this study the effects of in vitro DEP exposure (0.04–0.33 mg/mL) on IL-6, IL-8 production by a human bronchial epithelial cell line (BEAS-2B) were investigated. For comparison, the production of interleukins during exposure to silica and titanium oxide (TiO2) were also studied, representing relatively toxic and non-toxic particles, respectively. Scanning and transmission electron microscopy showed that the size of the DEP particles ranged between 25 to 35 nm and that DEP was phagocytized by BEAS-2B cells. An increase in IL-6 and IL-8 production (11-and 4-fold, respectively) was found after 24 or 48 h of exposure to DEP compared to the non-exposed cells. This increase was lower compared to silica (17-and 3.3-fold) and higher as compared to TiO2 which showed no increase for IL-6 and IL-8. To study the DEP effect on inflammation-primed cells, BEAS-2B cells were exposed to both tumor necrosis factor-α (TNF-α) and subsequently to DEP. Exposure to TNF-α caused a strong increase in IL-6 and IL-8 production. Additive effects on the IL-6 and IL-8 production by BEAS-2B cells were found after TNF-α priming and subsequently exposure to DEP, only at a low dose of DEP and TNF-α (0.05–0.2 ng/mL). In conclusion, BEAS-2B phagocytized DEP and produced an increased amount of IL-6 and IL-8. In TNF-α primed BEAS-2B cells, DEP increased interleukin production only at low concentrations of DEP and TNF-α. Whether this increased production of pro-inflammatory interleukins affects vulnerable balances in the immune system, such as T help-1 and T help-2 subsets ratios, resulting in an altered resistance to respiratory tract infections or altering the expression of respiratory allergy, is the subject of further studies.

Diesel exhaust particles induced release of interleukin 6 and 8 by (primed) human bronchial epithelial cells (BEAS 2b) in vitro

Several epidemiological studies have recently shown associations of increased premature mortality rates with ambient particulate air pollution. Diesel exhaust particles (DEP) may constitute an important part of (ultra)fine particulate air pollution in urban areas and may therefore contribute to its toxicity. Epithelial lining of the respiratory tract may be the first target of the toxic effects of DEP, that upon exposure may release pro-inflammatory mediators such as interleukin 6 and 8 (IL-6, IL-8), ultimately causing airway tissue damage and immune alterations. In this study the effects of in vitro DEP exposure (0.04-0.33 mg/mL) on IL-6, IL-8 production by a human bronchial epithelial cell line (BEAS-2B) were investigated. For comparison, the production of interleukins during exposure to silica and titanium oxide (TiO2) were also studied, representing relatively toxic and non-toxic particles, respectively. Scanning and transmission electron microscopy showed that the size of the DEP particles ranged between 25 to 35 nm and that DEP was phagocytized by BEAS-2B cells. An increase in IL-6 and IL-8 production (11- and 4-fold, respectively) was found after 24 or 48 h of exposure to DEP compared to the non-exposed cells. This increase was lower compared to silica (17- and 3.3-fold) and higher as compared to TiO2 which showed no increase for IL-6 and IL-8. To study the DEP effect on inflammation-primed cells, BEAS-2B cells were exposed to both tumor necrosis factor-alpha (TNF-alpha) and subsequently to DEP. Exposure to TNF-alpha caused a strong increase in IL-6 and IL-8 production. Additive effects on the IL-6 and IL-8 production by BEAS-2B cells were found after TNF-alpha priming and subsequently exposure to DEP, only at a low dose of DEP and TNF-alpha (0.05-0.2 ng/mL). In conclusion, BEAS-2B phagocytized DEP and produced an increased amount of IL-6 and IL-8. In TNF-alpha primed BEAS-2B cells, DEP increased interleukin production only at low concentrations of DEP and TNF-alpha. Whether this increased production of pro-inflammatory interleukins affects vulnerable balances in the immune system, such as T help-1 and T help-2 subsets ratios, resulting in an altered resistance to respiratory tract infections or altering the expression of respiratory allergy, is the subject of further studies.

大気汚染とＩｇＥ抗体産生

Earlier epidemiological studies have suggested a link between the increase in atomospheric pollutans and increases in the incidence and morbidity of allergic airway disease. The hallmark of these disease is an increase in the production of IgE. Diesel exhaust particles (DEPs) have been implicated in the increased incidence of allergic airway disorders among Japanese. We show that an extract of polyaromatic hydrocarbons from DEPs enhances human IgE production in purified B cells. The enhancement of the effects of DEPs on localized immunoglobulin production was demonstrated by performing nasal challenges with varying doses of DEP. These studies show that natural exposure to DEP may result in increased expression of respiratory allergic disease including Japanese cedar pollinosis and asthma.