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Preventing carbon nanoparticle-induced lung inflammation reduces antigen-specific sensitization and subsequent allergic reactions in a mouse model.

Kroker M, Sydlik U, Autengruber A, Cavelius C, Weighardt H, Kraegeloh A, Unfried K - Part Fibre Toxicol (2015)

Bottom Line: The presence of ectoine during the sensitization significantly reduced these parameters.The number of antigen-loaded dendritic cells in the draining lymph nodes was identified as a possible cause for the adjuvant effect of the nanoparticles.Using the intervention strategy of applying ectoine into the airways of animals we were able to demonstrate the relevance of neutrophilic lung inflammation for the adjuvant effect of carbon nanoparticles on allergic sensitization.

View Article: PubMed Central - PubMed

Affiliation: IUF - Leibniz Institut für Umweltmedizinische Forschung, Auf'm Hennekamp 50, 40225, Düsseldorf, Germany.

ABSTRACT

Background: Exposure of the airways to carbonaceous nanoparticles can contribute to the development of immune diseases both via the aggravation of the allergic immune response in sensitized individuals and by adjuvant mechanisms during the sensitization against allergens. The cellular and molecular mechanisms involved in these adverse pathways are not completely understood. We recently described that the reduction of carbon nanoparticle-induced lung inflammation by the application of the compatible solute ectoine reduced the aggravation of the allergic response in an animal system. In the current study we investigated the influence of carbon nanoparticles on the sensitization of animals to ovalbumin via the airways. Ectoine was used as a preventive strategy against nanoparticle-induced neutrophilic lung inflammation.

Methods: Balb/c mice were repetitively exposed to the antigen ovalbumin after induction of airway inflammation by carbon nanoparticles, either in the presence or in the absence of ectoine. Allergic sensitization was monitored by measurement of immunoglobulin levels and immune responses in lung and lung draining lymph nodes after challenge. Furthermore the role of dendritic cells in the effect of carbon nanoparticles was studied in vivo in the lymph nodes but also in vitro using bone marrow derived dendritic cells.

Results: Animals exposed to antigen in the presence of carbon nanoparticles showed increased effects with respect to ovalbumin sensitization, to the allergic airway inflammation after challenge, and to the specific TH2 response in the lymph nodes. The presence of ectoine during the sensitization significantly reduced these parameters. The number of antigen-loaded dendritic cells in the draining lymph nodes was identified as a possible cause for the adjuvant effect of the nanoparticles. In vitro assays indicate that the direct interaction of the particles with dendritic cells is not able to trigger CCR7 expression, while this endpoint is achieved by lung lavage fluid from nanoparticle-exposed animals.

Conclusions: Using the intervention strategy of applying ectoine into the airways of animals we were able to demonstrate the relevance of neutrophilic lung inflammation for the adjuvant effect of carbon nanoparticles on allergic sensitization.

No MeSH data available.


Related in: MedlinePlus

CNP exposure during sensitization leads to enhanced immune responses which can be attenuated by ectoine. a Experimental design, for sensitization, animals (n = 8) were treated with PBS, CNP, and CNP + E as described in Fig. 1. Additionally, 12 h after this treatment animals received 20 μg OVA. At day 21 serum was collected (S). After challenge (1 % OVA in PBS, 30 min) on three consecutive days (d32 – d34), animals were sacrificed and BAL, blood and lymph nodes were collected. b OVA-specific IgE prior to and after challenge. c Differential cell counts (representative plots and means, SEM) after challenge significance bar indicates differences in total cell numbers and neutrophil numbers. d CXCL1 levels in BAL after challenge. *p < 0.05, Mann Whitney U-test
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Fig2: CNP exposure during sensitization leads to enhanced immune responses which can be attenuated by ectoine. a Experimental design, for sensitization, animals (n = 8) were treated with PBS, CNP, and CNP + E as described in Fig. 1. Additionally, 12 h after this treatment animals received 20 μg OVA. At day 21 serum was collected (S). After challenge (1 % OVA in PBS, 30 min) on three consecutive days (d32 – d34), animals were sacrificed and BAL, blood and lymph nodes were collected. b OVA-specific IgE prior to and after challenge. c Differential cell counts (representative plots and means, SEM) after challenge significance bar indicates differences in total cell numbers and neutrophil numbers. d CXCL1 levels in BAL after challenge. *p < 0.05, Mann Whitney U-test

Mentions: Therefore, the effect of CNP on allergic sensitization was tested in a model of allergic airway inflammation in vivo (Fig. 2a). Lung inflammation was induced by the application of 2.5 mg/kg CNP in the presence or absence of 1 mM ectoine. At the peak of the inflammatory response, after 12 h, OVA was applied to the lower airways also by pharyngeal aspiration. After a recovery period of two days each, the procedure was repeated three times. In order to induce an allergic immune response, animals were challenged in an exposure chamber on three consecutive days. As described by de Haar et al. [12] sensitization via the airways in Balb/c mice leads to increased allergen specific IgE levels. We therefore monitored OVA specific IgE levels in the serum of the animals pre and post challenge (Fig. 2b). While only non-significant trends in OVA specific immunoglobulin were observed prior to the challenge, a significant increase of this parameter in CNP-exposed animals was observed after boosting. This effect was significantly lower when ectoine was applied to the airways during the sensitization phase, indicating a preventive effect of ectoine on the adjuvant effect of CNP. Similar effects were observed at the level of antigen-induced lung inflammation after challenge (Fig. 2c). BAL cells were identified by flow cytometry after staining with GR-1 and CD11c as described elsewhere [11]. OVA inhalation increased BAL cell numbers only in animals which were sensitized in the presence of CNP while animals sensitized in the presence of CNP and ectoine had significantly less inflammatory cells in the lung. This attenuation is mainly due to the significant reduction of neutrophils which is again reflected by the CXCL1 levels in BAL (Fig. 2d). Interestingly, predominantly the neutrophilic inflammation is affected by ectoine, the enhanced amount of eosinophils and lymphocytes in BAL, which might be induced by the induction of the allergic reaction is rather unaltered. As the inflammatory response is still dominated by neutrophil numbers, the effect on the other cell types might not be visible in the statistical analyses.Fig. 2


Preventing carbon nanoparticle-induced lung inflammation reduces antigen-specific sensitization and subsequent allergic reactions in a mouse model.

Kroker M, Sydlik U, Autengruber A, Cavelius C, Weighardt H, Kraegeloh A, Unfried K - Part Fibre Toxicol (2015)

CNP exposure during sensitization leads to enhanced immune responses which can be attenuated by ectoine. a Experimental design, for sensitization, animals (n = 8) were treated with PBS, CNP, and CNP + E as described in Fig. 1. Additionally, 12 h after this treatment animals received 20 μg OVA. At day 21 serum was collected (S). After challenge (1 % OVA in PBS, 30 min) on three consecutive days (d32 – d34), animals were sacrificed and BAL, blood and lymph nodes were collected. b OVA-specific IgE prior to and after challenge. c Differential cell counts (representative plots and means, SEM) after challenge significance bar indicates differences in total cell numbers and neutrophil numbers. d CXCL1 levels in BAL after challenge. *p < 0.05, Mann Whitney U-test
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4491258&req=5

Fig2: CNP exposure during sensitization leads to enhanced immune responses which can be attenuated by ectoine. a Experimental design, for sensitization, animals (n = 8) were treated with PBS, CNP, and CNP + E as described in Fig. 1. Additionally, 12 h after this treatment animals received 20 μg OVA. At day 21 serum was collected (S). After challenge (1 % OVA in PBS, 30 min) on three consecutive days (d32 – d34), animals were sacrificed and BAL, blood and lymph nodes were collected. b OVA-specific IgE prior to and after challenge. c Differential cell counts (representative plots and means, SEM) after challenge significance bar indicates differences in total cell numbers and neutrophil numbers. d CXCL1 levels in BAL after challenge. *p < 0.05, Mann Whitney U-test
Mentions: Therefore, the effect of CNP on allergic sensitization was tested in a model of allergic airway inflammation in vivo (Fig. 2a). Lung inflammation was induced by the application of 2.5 mg/kg CNP in the presence or absence of 1 mM ectoine. At the peak of the inflammatory response, after 12 h, OVA was applied to the lower airways also by pharyngeal aspiration. After a recovery period of two days each, the procedure was repeated three times. In order to induce an allergic immune response, animals were challenged in an exposure chamber on three consecutive days. As described by de Haar et al. [12] sensitization via the airways in Balb/c mice leads to increased allergen specific IgE levels. We therefore monitored OVA specific IgE levels in the serum of the animals pre and post challenge (Fig. 2b). While only non-significant trends in OVA specific immunoglobulin were observed prior to the challenge, a significant increase of this parameter in CNP-exposed animals was observed after boosting. This effect was significantly lower when ectoine was applied to the airways during the sensitization phase, indicating a preventive effect of ectoine on the adjuvant effect of CNP. Similar effects were observed at the level of antigen-induced lung inflammation after challenge (Fig. 2c). BAL cells were identified by flow cytometry after staining with GR-1 and CD11c as described elsewhere [11]. OVA inhalation increased BAL cell numbers only in animals which were sensitized in the presence of CNP while animals sensitized in the presence of CNP and ectoine had significantly less inflammatory cells in the lung. This attenuation is mainly due to the significant reduction of neutrophils which is again reflected by the CXCL1 levels in BAL (Fig. 2d). Interestingly, predominantly the neutrophilic inflammation is affected by ectoine, the enhanced amount of eosinophils and lymphocytes in BAL, which might be induced by the induction of the allergic reaction is rather unaltered. As the inflammatory response is still dominated by neutrophil numbers, the effect on the other cell types might not be visible in the statistical analyses.Fig. 2

Bottom Line: The presence of ectoine during the sensitization significantly reduced these parameters.The number of antigen-loaded dendritic cells in the draining lymph nodes was identified as a possible cause for the adjuvant effect of the nanoparticles.Using the intervention strategy of applying ectoine into the airways of animals we were able to demonstrate the relevance of neutrophilic lung inflammation for the adjuvant effect of carbon nanoparticles on allergic sensitization.

View Article: PubMed Central - PubMed

Affiliation: IUF - Leibniz Institut für Umweltmedizinische Forschung, Auf'm Hennekamp 50, 40225, Düsseldorf, Germany.

ABSTRACT

Background: Exposure of the airways to carbonaceous nanoparticles can contribute to the development of immune diseases both via the aggravation of the allergic immune response in sensitized individuals and by adjuvant mechanisms during the sensitization against allergens. The cellular and molecular mechanisms involved in these adverse pathways are not completely understood. We recently described that the reduction of carbon nanoparticle-induced lung inflammation by the application of the compatible solute ectoine reduced the aggravation of the allergic response in an animal system. In the current study we investigated the influence of carbon nanoparticles on the sensitization of animals to ovalbumin via the airways. Ectoine was used as a preventive strategy against nanoparticle-induced neutrophilic lung inflammation.

Methods: Balb/c mice were repetitively exposed to the antigen ovalbumin after induction of airway inflammation by carbon nanoparticles, either in the presence or in the absence of ectoine. Allergic sensitization was monitored by measurement of immunoglobulin levels and immune responses in lung and lung draining lymph nodes after challenge. Furthermore the role of dendritic cells in the effect of carbon nanoparticles was studied in vivo in the lymph nodes but also in vitro using bone marrow derived dendritic cells.

Results: Animals exposed to antigen in the presence of carbon nanoparticles showed increased effects with respect to ovalbumin sensitization, to the allergic airway inflammation after challenge, and to the specific TH2 response in the lymph nodes. The presence of ectoine during the sensitization significantly reduced these parameters. The number of antigen-loaded dendritic cells in the draining lymph nodes was identified as a possible cause for the adjuvant effect of the nanoparticles. In vitro assays indicate that the direct interaction of the particles with dendritic cells is not able to trigger CCR7 expression, while this endpoint is achieved by lung lavage fluid from nanoparticle-exposed animals.

Conclusions: Using the intervention strategy of applying ectoine into the airways of animals we were able to demonstrate the relevance of neutrophilic lung inflammation for the adjuvant effect of carbon nanoparticles on allergic sensitization.

No MeSH data available.


Related in: MedlinePlus