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Tze Khee Chan, BSc, Xin Yi Loh, BSc, Hong Yong Peh, BSc, W. N

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Presentation on theme: "Tze Khee Chan, BSc, Xin Yi Loh, BSc, Hong Yong Peh, BSc, W. N"— Presentation transcript:

1 House dust mite–induced asthma causes oxidative damage and DNA double-strand breaks in the lungs 
Tze Khee Chan, BSc, Xin Yi Loh, BSc, Hong Yong Peh, BSc, W.N. Felicia Tan, BSc, W.S. Daniel Tan, BSc, Na Li, PhD, Ian J.J. Tay, BEng, W.S. Fred Wong, PhD, Bevin P. Engelward, ScD  Journal of Allergy and Clinical Immunology  Volume 138, Issue 1, Pages e1 (July 2016) DOI: /j.jaci Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

2 Fig 1 HDM induces inflammatory cell recruitment to the airway. A, HDM-induced airway inflammation model. B, Quantification of immune cells in BAL fluid 1, 3, 5, and 10 days after challenge (d.p.c). Total immune cells (Total), alveolar macrophages (Alveo Φ), eosinophils (Eos), neutrophils (Neu), and T lymphocytes (T cells) were quantified. Values are means ± SEMs. C, Representative images of hematoxylin and eosin–stained lungs. Quantification of inflammatory cell infiltration in lungs was done according to the method of Bao Z et al.26 Micrographs were taken at ×200 magnification. *P < .01 and #P < .05, significant difference from saline control (S). Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

3 Fig 2 Increased levels of oxidative damage in BAL fluid and lung tissues. Estimated level of ROS in BAL fluid obtained from mice 3 days after challenge (d.p.c), as measured by using the DCFH-DA assay. Levels of 8-isoprostane, 3-NT, and 8-OHdG/8-oxoG were measured by using ELISA and immunofluorescence staining of lung sections (bottom right). The negative control (-ve) indicates secondary antibody alone. Values are means ± SEMs. *P < .01 and #P < .05, significant difference from saline control (S). Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

4 Fig 3 Asthma induces DNA DSBs in lungs of asthmatic mice and human subjects. A, Analysis of γH2AX (green), CC10 (red), and 4′-6-diamidino-2-phenylindole dihydrochloride (DAPI; blue) in lung sections. The negative control (-ve) indicates secondary antibody alone, and the positive control indicates lung tissue treated with bleomycin (Bleo). B, Quantification of γH2AX-positive cells (≥5 foci). C, γH2AX protein levels measured by means of immunoblotting. D, Analysis of γH2AX (green) in human normal and asthmatic lung tissue. E, Quantification of γH2AX-positive cells (≥5 foci). F, γH2AX protein levels quantified by using immunoblotting. Values are means of 3 ± SEMs. *P < .01, significant difference from healthy control tissue. d.p.c, Days after challenge. Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

5 Fig 4 HDM induces direct DNA DSBs in BEAS-2B cells. A, Representative images of alkaline comets. Percentage of DNA intensity in the comet tail, which reflects the level of DNA damage, was quantified. B, Cells were stained for γH2AX (green), and nuclei were stained with 4′-6-diamidino-2-phenylindole dihydrochloride (DAPI; blue). Cells with 10 or more foci were counted as positive. C, Cells were stained with CellROX to measure oxidative stress levels. All experiments were repeated at least 3 times, and data are presented as means ± SEMs. *P < .01 and #P < .05, significant difference from untreated. Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

6 Fig 5 Asthma induces DNA damage responses, as indicated by increased Rad51, Ku70, PARP-1, and PAR levels. A, Lung protein extract analyzed by means of Western blotting for Rad51, Ku70, PARP-1, and PAR. B, Human lung lysates from normal or asthmatic lung tissue were immunoblotted with Rad51, Ku70, and PAR antibodies. β-Actin serves as an internal control. Images show representative results for one of 3 or more experimental replicates. d.p.c, Days after challenge. Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

7 Fig 6 DNA repair inhibitor increases DNA DSBs and DNA damage responses. A, Analysis of DNA DSBs by using neutral comet analysis after exposure to γIR. Tail length reflects the frequency of DNA DSBs.33 B, NU7441 treatment timeline. C, Lung sections were stained for γH2AX (green), CC10 (red), and 4′-6-diamidino-2-phenylindole dihydrochloride (DAPI; blue). D, Quantification of cells positive for γH2AX (≥5 foci), excluding cells with pan-nuclear γH2AX staining. E, Lung protein extracts were analyzed by immunoblotting for γH2AX, Ku70, Rad51, and PARP-1. Experiments were repeated at least 3 times. *P < .01, significant difference from HDM-only control. d.p.c, Days after challenge. Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

8 Fig 7 NU7441 increases proinflammatory cytokine production and induces cell death in BEAS-2B cells exposed to HDM. A, IL-4, IL-5, IL-13, IL-33, thymic stromal lymphopoietin (TSLP), and IFN-γ levels in culture supernatants were quantified by using ELISA. B, Cell death assay was performed with Annexin V/PI staining. Annexin V+PI− and Annexin V+PI+ cells were considered dead cells. All experiments were repeated at least 3 times, and values are shown as means ± SEMs. *P < .01 and #P < .05, significant difference from HDM-alone control. Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

9 Fig 8 Asthma-induced cell death is enhanced by NU7441. A, Immunoblotting of cleaved caspase-3 and caspase-activated DNase (CAD). B, Immunoblotting of cleaved caspase-3 in lungs of subjects with HDM-induced asthma with and without NU7441 treatment. C, Analysis of apoptosis by using terminal deoxynucleotidyl transferase–mediated dUTP nick end-labeling (TUNEL) staining, where apoptotic cells are stained brown. The negative control (-ve) indicates staining without terminal deoxynucleotidyl transferase enzyme. The positive control (+ve) indicates lungs treated with DNase I. D, Quantification of TUNEL-positive cells. Values are shown as means ± SEMs. *P < .01, significant difference from HDM-only control. d.p.c, Days after challenge. Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

10 Fig E1 Effects of NU7441 on HDM-induced AHR. AHR of mechanically ventilated mice in response to aerosolized methacholine was measured 3 days after the last saline or HDM challenge with or without NU7441 treatment. AHR is expressed as fold change over baseline level. A, Lung resistance (RI, n = 6 mice) defined as the pressure driving respiration divided by flow. B, Dynamic compliance (Cdyn, n = 6 mice), referring to the dispensability of the lung and defined as the change in lung volume produced by a change in pressure across the lung. Values are shown as means ± SEMs. Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions

11 Journal of Allergy and Clinical Immunology 2016 138, 84-96. e1DOI: (10
Journal of Allergy and Clinical Immunology  , e1DOI: ( /j.jaci ) Copyright © 2016 American Academy of Allergy, Asthma & Immunology Terms and Conditions


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