1. “Tracheobronchial” Clearance Fast clearance from the bronchi and bronchioles J E Agnew Royal Free Hampstead NHS Trust and Royal Free & University College Medical School

2. The Lungs: Function, Diagnosis and Treatment What do the Lungs do? How do they do it? Being Scientific Weighing-up Evidence Making Models Testing Ideas Aerosol Clearance Mucus Clearance Effect of Disease Diagnosis Treatment Long-term Retention Adverse Effects

5. The ICRP Respiratory Tract Model

6. ET BB bb Lymph Nodes Blood GI tract AI Clearance Routes from the Respiratory Tract based on the ICRP model ICRP Publication 66

7. NCRP Model

8. Bronchi BB Bronchioles bb 100 mins 8 hours ICRP reference BB and bb half-times

9. Timescales for Tracheobronchial and Pulmonary Clearance as set out in NCRP 1997

10. Aerosol Particles Inert polystyrene particles 5  m diameter Tc-99m labelled Inhaled “slowly” Retention measured 0-6h & 24h Initial Gamma Camera Image

12. Intermediate Zone Outer Zone Control FET Tracheobronchial Clearance - intermediate and outer zones % 19 patients with mucus hypersecretion Hasani et al. 1994

13. The Lungs ?

16. Conductive Airways “….Examination reveals that each bronchus divides into two distal bronchi. This pattern of branching is called dichotomy and is frequently observed in nature. The dichotomous branching may sometimes be obscured by considerable variation in the length of the elements. Nevertheless, of more than 1000 branchings analyzed…, all of them could be characterized as dichotomous. The irregularity in the dimensions of the elements is related to the shape of the lung. After four generations of airway branching… the basic shape of the lung appears to be outlined.” Weibel and Gomez 1962

18. Branching Structure of the Airways Weibel,1991 original version Weibel, 1963

19. The ‘Tracheo- bronchial’ tree from Contours of Breathing (1980) based on Weibel (1963)

20. Bronchial Epithelium (seen in cross-section) Royal Free

21. This is what cilia look like ??? Royal Free

22. Or like this ??? Royal Free

23. Or like this ??? Royal Free

24. Tracheal epithelium BCbasal cells TBCtall basal cells CCciliated cells GCgoblet cells ICintermediate cells Evans et al Exp Lung Res 2001: 27: 401-5

25. Airway epithelium protects submucosa is metabolically active synthesises and releases pro-inflammatory factors influences inflammatory cells - chemotaxis -recruitment -activation -differentiation Patel et al. Eur Respir J 2003: 22: 94-9

26. Airway epithelium Following an inflammatory stimulus, COPD bronchial epithelial cells: show significant cytokine* response response may be modified by inhaled steroids *interleukin (IL)-6 and (IL)-8 Patel et al. Eur Respir J 2003: 22: 94-9

27. Bronchial epithelium (after hexadecane stimulus) MUC mucus GC goblet cell Green et al in Particle-Lung Interactions ed. Gehr and Heyder Marcel Dekker 2000

28. Royal Free Ciliary Structure (1)

29. Royal Free Ciliary Structure (2)

30. Interaction of cilia and mucus see Knowles and Boucher J Clin Invest 2002: 109: 571-7 + other papers from Chapel Hill group

31. Maintaining Airway Surface Liquid Depth - ? Stationary or Moving Periciliary Liquid Layer Model 1: NaCl transepithelial transportModel 2: NaCl and water transport Matsui et al. J Clin Invest 1998 102: 1125-31

32. Airway Surface Liquid = Mucus + Underlying watery periciliary liquid (PCL) Used to be thought that PCL was ~ stationary Now cell culture studies show PCL movement Mucus39.2 ± 4.7  m/sec PCL39.8 ± 4.2  m/sec But if you take the mucus away: PCL4.8 ± 4.2  m/sec Matsui et al. J Clin Invest 1998 102: 1125-31

33. Airway Surface Liquid “The cephalad movement of PCL along airway epithelial surfaces makes.. mucus-driven transport an important component of salt and water physiology in the lung in health and disease.” Matsui et al. J Clin Invest 1998 102: 1125-31

34. Red = ASL, green = mucus (attached fluorescent beads) Change osmolality (of bath) and layers shrink or swell. Conclusion: “liquid is being donated from the mucus layer to the PCL and vice versa in a spongelike fashion…” Tarran et al. J Gen Physiol 2001: 118: 223-36 Active ion transport regulates ASL height... feedback between ASL and epithelia governs rate of ion transport and volume absorption. [?]

35. Tarran et al. J Gen Physiol 2001: 118: 223-36 Mucus transport - as seen by time-lapse photos in cell culture experiments

36. Pulmonary Defence mechanisms - against chronic bacterial infection Knowles & Boucher J Clin Invest 2002: 109: 571-7

37. Isotonic Volume Transport Model Active Na + Absorption Boucher. J Physiol 1999: 516: 631-8

38. Isotonic Volume Transport Model superficial airway cells Boucher. J Physiol 1999: 516: 631-8

39. Isotonic Volume Transport Model submucosal gland ducts absorb NaCl but not water Boucher. J Physiol 1999: 516: 631-8

40. “Hypotonic ASL physiology” Boucher. J Physiol 1999: 516: 631-8

41. Restoration of water balance in ASL Boucher. J Physiol 1999: 516: 631-8

42. Knowles & Boucher J Clin Invest 2002: 109: 571-7 Airway Epithelial Culture good/bad indicator of clearance effectiveness in real life ?

46. Clearance measurements depend on deposition distribution Pavia 1985

47. ICRP 66 based on Burri & Weibel 1973

48. Pavia 1985

50. Clearance rests when you’re asleep The effect of sleep rather than inactivity

51. Pavia 1984 Mild asthmatics have worse daytime clearance than control subjects - their clearance during sleep is about as bad as that seen in control subjects

52. Effect of inhaling mannitol (patients with bronchiectasis) Daviskas et al. Am J Respir Crit Care Med 1999: 159: 1843-8

53. Daviskas et al. Am J Respir Crit Care Med 1999: 159: 1843-8

54. The importance of cough Foster WM Pulm Pharmacol Ther 2002: 15: 277-82

55. Measuring and calculating retention …………..

61. Can we relate clearance (or clearance changes) to deposition distribution (or distribution changes) ? p < 0.05

62. Effect of a long-acting bronchodilator on mucociliary clearance measured by an aerosol method Change in retention Change in “R 48 ” Change in PEFR p = 0.06p = 0.18

63. Effect of a long-acting bronchodilator on mucociliary clearance measured by an aerosol method - continued Multiple regression: p = 0.03 Is this an appropriate new approach ?

64. Effect of amiloride on muco- ciliary clearance Sood et al. Am J Respir- Crit Care 2003 167: 158-63

68. Transit times through the bronchioles

69. Smoker Non-smoker “The foot of the mucociliary escalator goes deeper in smokers than in non-smokers”

70. Intermediate Zone Outer Zone Control FET Tracheobronchial Clearance - intermediate and outer zones % 19 patients with mucus hypersecretion Hasani et al. 1994

72. Clearance - Mucociliary / Cough Whole Lung / Tracheobronchial Cough-corrected ( ? how) Dependence on Deposition Distribution Mucus / Salt and Water Effects of Medication / Physiotherapy