8. Asthma & Bronchiectasis - Cox

• asthma is transient airway obstruction

  • episodic increases in airway resistance
• non-atopic (intrinsic) asthma is not triggered by allergy

  • maybe IL-10 mediated neutrophil influx and activation
• atopic or allergic asthma is initiated by type 1 hypersensitivity

  • induced by exposure to extrinsic antigen
• Atopic asthma or allergic asthma - associated with

  • increased serum IgE levels
  • eosinophilia
  • positive skin test with offending antigen
• allergic asthma typically develops children with positive family history of allergic disease
• Different phases of atopic asthma

  • sensitization
  • re-exposure
  • early or immediate phase
  • late phase
• atopic asthma - early phase

  • initial sensitization to an inhaled allergen
  • inhaled Ag phagocytized antigen presenting cells leads to
  • induction of CD4 Th2 cells
  • IgE production by B cells
  • IgE binds to mast cell Fc receptor
• Allergic asthma - re-exposure early phase

  • antigen binds to mast cells bound IgE
  • antigen induced IgE cross-linking
  • mast cell degranulation
  • release histamine and mediators
• Mediators that is released by mast cell can induce

  • bronchoconstriction
  • leads to airway narrowing
  • increase vascular permeability
  • increase mucin secretion
• atopic asthma - late phase

  • vasodilation

  1. increased permeability
  2. edema
  3. increase airway narrowing

  • mediator will attract other inflammatory cells
  • T cell lymphocyte
  • macrophages
  • eosinophils
• atopic asthma - late phase

  • vasodilation

  1. increased permeability
  2. edema
  3. increase airway narrowing

  • mediator will attract other inflammatory cells
  • T cell lymphocyte
  • macrophages
  • eosinophils - release major basic protein (MBP)
  • cause epithelial damage
  • respiratory epithelium necrosis
• Asthma will cause hyperinflation of lungs

  • chronic attacks will remodeling
  • inflammatory infiltrates --> increase eosinophil count
• Asthma - there will be mucus plug

  • due to thicken dehydrated mucus
  • increase mucus from hypertrophied bronchial submucosal glands
• Formation of mucus plug in asthma

  • Bronchoconstriction
  • mucus congeals to form mucus plug
• How can mucus plug affect people with asthma?

  • obstruct airways
  • coughed up by patient during asthmatic attacks
• What can be seen in cells of people with asthma?

  Charcot leyden crystals

  
• What can be seen microscopically in mucous cast in people with asthma?

  Curschmann’s spirals

  
• Bronchiectasis - permanent dilation of bronchi

  • secondary to disease process like COPD
• How is bronchiectasis developed

  1. tissue damage due to repeated inflammation
  2. weakening muscular and elastic component of bronchial walls
  3. severely impaired mucus clearance
  4. impaired clearance - increase risk of infection
• Bronchiectasis can be cause by aspergillus
• What is the vicious cycle for bronchiectasis

  1. bronchial damage
  2. bronchial dilation
  3. impaired mucus clearance
  4. recurrent infection
• Bronchiectasis is due to dilated bronchus

  • loss of
  • smooth muscles
  • elastic fibers
  • cartilage
  • inflammatory cells line airways
  • neutrophil infiltration