Pathogenesis of bronchial asthma
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Transcript of Pathogenesis of bronchial asthma
PBL Session 3
Rosshini Jagatheswaran
Describe the PATHOGENESIS of bronchial asthma
MUST KNOW Learning Outcome
How T helper cells work?
TH2 cells secrete cytokines IL-4, IL-5, IL-13
stimulate B cells to produce IgE and other
antibodies.
IL-4 stimulates the production of IgE
IL-5 activates locally recruited eosinophils
IL-13 stimulates mucus secretion from bronchial submucosal glands and also promotes IgE production by B cells
Sensitization to Allergen• Inhaled allergens• TH2– dominated response
• IgE productions• Eosinophil recruitment• Release of granules and mediators
Allergen-Triggered Asthma• Re-exposure• Ag-induced cross linking of IgE bound to IgE
receptors on mast cell• Mediators released – histamine, leukotrienes• Tight junctions between epithelial cells open• Antigen enter mucosa• Mucosal mast cells activated• Eosinophil release other mediators
• Leukotrienes - constriction of bronchi bronchospasm - increased mucus production mucosal
accumulation• Histamine
- increased vascular permeability swelling & redness edema
- increased mucus production mucosal accumulation• Eosinophilic chemotactic factor
- Chemotaxis of eosinophils accumulation of eosinophils
Late Phase• Recruited leukocytes
initiate late phase• Mediators release
from endothelium, epithelial cells, leukocytes
• Eosinophils MBP, ECP – damage epithelium
Comparison of a normal bronchiole with that in a patient with asthma
• Increase in the number of mucus-secreting goblet cells in the mucosa and hypertrophy of submucosal mucus glands Accumulation of mucus in the bronchial lumen
• Recruitment of eosinophils & macrophages intense chronic inflammation
• Thickened basement membrane • Hypertrophy & hyperplasia of smooth muscle
cells
POP-QUIZWhich T Helper Cell plays an important role in bronchial asthma?What happens after IgE binds to the mast cell in the first phase-sensitization phase?Leukotrienes causes …?Upon re-exposure of Ag, what happens after binding of IgE?
Some factors released by eosinophils in the late phase causes damage to the epithelium. Give 2 examples of the factors.
Give 2 differences of a normal bronchiole and bronchiole of an asthmatic patient.
THANK YOU