Asthma - Pathogenesis
Dr.MD RAIHAN
MD(PATHOLOGY)
What is Asthma?
• Heterogenous disease
• Chronic airway inflammation
• Expiratory airflow obstruction
• Symptoms
• Wheezing
• Shortness of breath
• Chest tightness
• cough
Major subtypes
• AtopicAsthma
• Type 1 hypersensitivity
• Childhood
• Environmental allergens
• Positive family history
• High total serum IgE levels
• Serum radioallergosorbent tests
• NonAtopic asthma
• No evidence of sensitization
• Less common family history
• Associated with
• Viral respiratory infections
• Air pollutants
• Cold
Major subtypes
• Occupational asthma
• Fumes
• Dusts
• Chemicals
• Even minute quantities are
sufficient
• Repeated exposure
• Drug – Induced asthma
• Aspirin sensitive asthma
• NSAIDs
• Associated with utricaria
Inhibition of COX
Arachidonic acid not
metobolised
Less Prostaglandin E2
Pathogenesis
• Th2 responses, IgE and Inflammation
• Genetic susceptibility
• Environmental factors
Th2 responses, IgE and Inflammation
Th2 cells
IL -4
Ig E
production
IL – 5
Eosinophil
recruitment
IL – 13
Endobronchial
Secretions
Th 17
IL – 17
Neutrophil
recruitment
Triggering of Asthma
Early Phase
Bronchoconstriction
Increased mucus production
Vasodilation
Vascular permeability
Late Phase
Recruitment of Leucocytes
- Eosinophils
- Neutrophils
- More T cells
Mediators
Definite
Leucotrienes
C4, D4 & E4
Acetylcholi
ne
IL -5
Galectin 10
Minor
role
Histamine
Prostagland
in D2
PAF
Others
IL – 4
IL – 13
TNF
Genetic susceptibility
• Chromosome 5q
• Gene cluster encoding for IL3, IL4, IL5, IL9, IL13 & IL4 receptor
• Class II HLAalleles
• Genes encoding
• IL33
• Thymic stromal lymphoprotein
Environmental factors
Industrial
Air
pollutants
Hygiene
hypothesis
Exaggerated response
Airway Inflammation
Airway Dysfunction
Airway remodelling
Normal vs Asthmatic Airway
Gross
• Hyperinflated lungs
• Occlusion of bronchi by thick,
tenacious mucus plugs
Microscopy
• Airway wall thickening
• Eosinophilic inflammation
• Goblet cell hyperplasia
• Muscle hypertrophy
• Sub basement membrane
fibrosis
• Increased vascularity
• Increased size of submucosal
glands
BAL Wash findings
Curschmann spirals Charcot leyden crystals
References
• Robbins and Cotran pathologic basis of disease
• Autopsy pathology –Amanual and atlas,Andrew J. Connolly
• Comprehensive Cytology, Marluce Bibbo

asthma-pathogenesis-230531144001-56d3d3c9.pptx