9th ETH Conference on CGP: 16. August 2005 Distribution and Clearance of Inhaled Ultrafine TiO 2 Particles in Rat Lungs

Transcription

1 9th ETH Conference on CGP: 16. August 2005 Distribution and Clearance of Inhaled Ultrafine TiO 2 Particles in Rat Lungs Marianne Geiser University of Bern Airways & alveoli - rodent lung TiO 2 particle in fibroblast rat lung

2 Aim of studies at the ultrastructural level > Resolve distribution patterns, retention and clearance pathways at the individual particle level > Increase knowledge of particle-lung (cell) interaction to better understand adverse and beneficial effects by inhaled particles

3 Particle types (insoluble PM 10) Polystyrene Teflon 2 µm 2 µm Puffball spores MMVF 10a 2 µm 10 µm

4 Displacement of PM 10 by surfactant Air Surfactant Macs Aqueous Phase Airway / Alveolar wall (epithelium, connective tissue, etc.)

5 Inhaled and deposited PM 10 Glass fiber in conducting airway Puffball spore in alveolus 5 µm Puffball spores in alveoli 0.5 µm 5 µm

6 MMVF 10a in blood capillaries Most profiles with > diameter 1µm > angular surface 1 µm Translocation of the particulate fraction of glass fibers beyond the epithelial barrier

7 Inhalation experiment with ultrafine particles > Titanium dioxide (TiO 2 ) > Aerosol: 22 nm CMD > Inhalation: 1 h > Deposition: 4-5 µg, particles > Lung fixation: 1 h / 24 h after inhalation > Systematic tissue sampling > Energy filtering TEM (EFTEM): Electron-energy loss spectroscopy (EELS)

8 Aerosol generation and inhalation Dr. Wolfgang Kreyling anesthetized intubated rats ventilated in plethysmographs sample O 2 N 2 HUM CPC DMPS Kr Pa Control Ti Ti spark generator Pa O (0.1%) 2 Ar

9 Size distribution of TiO 2 particles in the aerosol CMD = 22 nm

10 Inhalation experiment with ultrafine particles > Titanium dioxide (TiO 2 ) > Aerosol: 22 nm CMD > Inhalation: 1 h > Deposition: 4-5 µg, particles > Lung fixation: 1 h / 24 h after inhalation > Systematic tissue sampling > Energy filtering TEM (EFTEM): Electron-energy loss spectroscopy (EELS)

11 Localization and elemental micro-analysis of ultrafine TiO 2 particles Localization in lung tissue Elemental microanalysis

12 TiO 2 particles in the lung parenchyma EP EN EP EP LB LB LB S LB AL 100nm 100nm On the alveolar surface Within pneumocyte Type 2

13 TiO 2 particles in the connective tissue 500 nm 500 nm 500 nm Between collagen fibrils Within fibroblast (cytoplasm) Within fibroblast (nucleus)

14 TiO 2 particles in blood capillaries AL S CA EN EN CA 500 nm 100nm 500 nm Within endothelial cell In blood capillary Within erythrocyte

15 Distribution of TiO 2 particles in the lungs Volume density (V v ) of lung compartment Percentage of particle profiles V(v) 1h 24h Mean Airspace Epithelium, Endothelium Connective tissue Lung tissue compartment Blood vessels Geiser et al., Environ Health Perspect: doi: /ehp.8006, 2005

16 Size distribution of TiO 2 particles in the aerosol and in lung sections

17 Summary Ultrafine TiO2 particles > Penetrate through the surface lining layer and the epithelial barrier > Distribute rapidly and evenly in all lung tissues and cells > Are not membrane bound within cells > Overwhelm the biological membranes by a yet unknown mechanism

18 Collaborators, Support and most recent References > P. Gehr, V. Im Hof, N. Kapp S. Frank, B. Kupferschmid (University of Bern, Bern, CH) > W. Kreyling, H. Schulz, M. Semmler (GSF-Neuherberg, Munich, FRG) > L.M. Cruz-Orive (University of Cantabria, Santander, E) > Swiss National Science Foundation (SNF) > Silva Casa Foundation > Swiss Agency for the Environment, Forest and Landscape (BUWAL) > Geiser M. et al., J Appl Physiol 94, 2004 > Kapp N. et al., Micr Res Techn 63, 2004 > Geiser M. et al., Environ Health Perspect, doi: /ehp.8006, 2005

19 Possible consequences from particle translocation into the lung tissue Adapted from Gehr et al., Phil. Trans. R. Soc. Lond. A, 2000

20 Focus of current and future in vivo studies Thick mucus layer Adapted from Gehr et al., Phil. Trans. R. Soc. Lond. A, 2000

21 Clearance of ultrafine TiO 2 particles by macrophages 500nm 500nm N macs N part P cytoplasm /P vesicles P nucleus 1 h h Total

22 Translocation of ultrafine TiO 2 particles into secondary organs 500 nm 500 nm 500 nm Liver Hepatocyte (mitochondrium) Liver Hepatocyte (cytoplasm) Heart Between myofilaments

23 Collaborators and Support > M. Casaulta, B. Kupferschmid (University of Bern, Bern, CH) > W. Kreyling, H. Schulz, M. Semmler (GSF-Neuherberg, Munich, FRG) > L.M. Cruz-Orive (University of Cantabria, Santander, E) > Swiss National Science Foundation (SNF) >?

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25 Transport of ultrafine particles through the nuclear pore complex 22-nm gold 26-nm gold Panté & Kann, Mol Biol Cell, 2002

26 9th ETH Conference on CGP: 16. August 2005 Distribution and Clearance of Inhaled Ultrafine TiO 2 Particles in Rat Lungs Marianne Geiser University of Bern Airways & alveoli - rodent lung Puffball spores in airways and alveoli

27 Components of the inner surface of the lungs Air Surfactant Macs Aqueous Phase Airway / Alveolar wall (epithelium, connective tissue, etc.)

28 Displacement of PM 10 by surfactant Polystyrene Teflon Air Surfactant Macs Aqueous Phase Puffball spores Airway / Alveolar wall (epithelium, connective tissue, etc.) MMVF 10a

29 The concept of PM 10 retention and clearance Adapted from Cell and Tissue Biology by L. Weiss, Urban & Schwarzenberg Inc. 1988

30 In vivo: Rodent model > Aerosol generation by nebulization > Aerosol inhalation via endotracheal tube > Continuous negative-pressure ventilation > Lung fixation by vascular triple perfusion > Systematic tissue sampling > Light and electron microscopy

31 Inhaled and deposited PM 10, by SEM 5 µm 5 µm Glass fiber in conducting airway Puffball spores in alveoli

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35 Deposition of ultrafine particles Diffusion Impaction Sedimentation From Schulz et al., Lenfant Series, 2000

36 Ultrastructure of the lung parenchyma Air-blood barrier = 2 µm 1/50 Air mail paper

37 Deposition of ultrafine particles in lungs > High deposition rate > Alveolar surface = 140 m 2 > Air-blood barrier = 2 µm From Schulz et al., Lenfant Series, 2000

38 Animal model: Lung fixation

39 Systematic tissue sampling for stereologic analysis

40 Distribution of TiO 2 particles in the lungs Volume density (V v ) of lung compartment Percentage of particle profiles V(v) 1h 24h Mean Airspace Epithelium, Endothelium Connective tissue Lung tissue compartment Blood vessels

41 Electron beam - specimen interactions

42 Electron filtering TEM Poly-energetic electrons Objective aperture Angle selection Slit aperture Energy selection Mono-energetic electrons

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