Asthmatic
Asthma
Definition:
Asthma is a chronic inflammatory disorder of the airways characterized by
variable airflow obstruction, airway hyperresponsiveness, mucus
hypersecretion, and recurrent episodes of wheezing, cough, chest tightness,
and shortness of breath. Airflow limitation is often reversible, but chronic
inflammation can produce airway remodeling and more persistent obstruction.
Main Pathways Involved in Asthma — Ranked by Importance
| Rank |
Pathway / Target |
Typical Direction in Asthma |
Importance |
Role |
| 1 |
IL-4 / IL-13 → JAK / STAT6 |
↑ |
Very High |
Central Type-2 asthma pathway. Promotes Th2 responses, IgE production,
mucus hypersecretion, airway hyperresponsiveness, and remodeling.
|
| 2 |
IL-5 → Eosinophils |
↑ |
Very High |
Drives eosinophil maturation, survival, recruitment, and activation.
A major pathway in eosinophilic asthma and a clinically validated
therapeutic target.
|
| 3 |
IL-33 → ST2 / IL1RL1 → ILC2 |
↑ |
Very High |
Major upstream epithelial alarmin pathway. Activates ILC2 and promotes
IL-5 and IL-13 production, eosinophilia, mucus secretion, and airway
hyperresponsiveness.
|
| 4 |
TSLP |
↑ |
Very High |
Epithelial alarmin that activates dendritic cells, Th2 immunity,
mast cells, and ILC2. Particularly important in allergic and severe
Type-2 asthma.
|
| 5 |
IgE → FcεRI → Mast-cell activation |
↑ |
Very High |
Fundamental allergic-asthma pathway. Allergen-mediated IgE
cross-linking activates mast cells and causes release of histamine,
leukotrienes, prostaglandins, and cytokines.
|
| 6 |
5-LOX / ALOX5 → LTC4 / LTD4 / LTE4 → CysLT1 |
↑ |
Very High |
Cysteinyl leukotrienes are potent bronchoconstrictors and promote
mucus secretion, vascular permeability, and eosinophilic inflammation.
|
| 7 |
Airway smooth muscle / β2-adrenergic receptor → cAMP / PKA |
Contraction ↑; therapeutic β2 signaling ↑ |
Very High |
Airway smooth-muscle contraction directly causes reversible airflow
obstruction. β2-receptor activation increases cAMP and PKA,
producing bronchodilation.
|
| 8 |
NF-κB |
↑ |
High |
Major inflammatory transcription pathway controlling cytokines,
chemokines, adhesion molecules, inflammatory enzymes, and immune-cell
activation.
|
| 9 |
TGF-β1 → SMAD2 / SMAD3 |
↑ |
High |
Major driver of chronic airway remodeling, extracellular-matrix
deposition, subepithelial fibrosis, and airway smooth-muscle growth.
|
| 10 |
ROS / Oxidative Stress ↔ Nrf2 |
ROS ↑; Nrf2 often insufficient |
High |
Oxidative stress damages airway epithelium and amplifies NF-κB,
MAPK, cytokine signaling, mucus production, and airway
hyperresponsiveness. Nrf2 provides a protective antioxidant response.
|
| 11 |
IL-17 / Th17 → CXCL8 / IL-8 → Neutrophils |
↑ |
High in Severe / Non-Type-2 Asthma |
Important in neutrophilic, severe, and corticosteroid-resistant asthma.
Promotes neutrophil recruitment and persistent airway inflammation.
|
| 12 |
NLRP3 Inflammasome → IL-1β / IL-18 |
↑ |
Moderate-High |
Promotes innate inflammatory signaling and neutrophilic airway
inflammation, particularly in severe and non-Type-2 asthma.
|
| 13 |
PI3K / AKT |
↑ |
Moderate |
Supports inflammatory-cell survival, airway smooth-muscle
proliferation, mucus production, and corticosteroid resistance.
|
| 14 |
MAPK / ERK / p38 / JNK |
↑ |
Moderate |
Regulates cytokine production, epithelial responses, smooth-muscle
activity, inflammatory-cell activation, and airway remodeling.
|
| 15 |
Epithelial Barrier Integrity |
↓ |
Moderate |
Impaired epithelial integrity allows greater allergen penetration and
promotes release of IL-33, TSLP, and IL-25.
|
| 16 |
E-cadherin / ZO-1 |
↓ |
Moderate |
Reduced adherens-junction and tight-junction proteins contribute to
impaired airway-barrier function and increased inflammatory signaling.
|
| 17 |
MUC5AC / Goblet-cell Hyperplasia |
↑ |
Moderate |
Drives mucus hypersecretion and mucus plugging, particularly under
IL-13 signaling.
|
| 18 |
CCL11 / Eotaxin-1 → CCR3 |
↑ |
Moderate |
Recruits eosinophils into airway tissue and contributes to Type-2
airway inflammation.
|
| 19 |
TNF-α |
↑ |
Moderate |
Promotes inflammatory-cell recruitment, endothelial activation,
airway hyperresponsiveness, and remodeling.
|
| 20 |
NADPH Oxidase / NOX |
↑ |
Moderate |
Generates reactive oxygen species and contributes to oxidative injury
and inflammatory signaling.
|
| 21 |
VEGF |
↑ |
Secondary / Remodeling |
Promotes increased airway vascularity, vascular permeability, and
airway-wall remodeling.
|
| 22 |
MMP-9 |
↑ |
Secondary / Remodeling |
Extracellular-matrix remodeling enzyme associated with inflammation,
epithelial injury, and structural airway changes.
|
| 23 |
Collagen Deposition |
↑ |
Secondary / Remodeling |
Contributes to subepithelial fibrosis, airway-wall thickening, and
progressively less reversible airflow obstruction.
|
Core Asthma Pathway Summary
Primary Type-2 pathway:
Allergen / epithelial injury
→ IL-33 + TSLP + IL-25 ↑
→ ILC2 + dendritic cells + Th2 ↑
→ IL-4 + IL-5 + IL-13 ↑
→ IgE ↑ + eosinophils ↑ + mast-cell activation ↑
→ bronchoconstriction + mucus ↑ + airway hyperresponsiveness.
Allergic effector pathway:
Allergen
→ IgE / FcεRI
→ mast-cell degranulation
→ histamine + prostaglandins + cysteinyl leukotrienes
→ acute bronchoconstriction and airway inflammation.
Oxidative / inflammatory pathway:
Allergens / pollutants / inflammatory cells
→ ROS ↑
→ NF-κB + MAPK + PI3K / AKT ↑
→ inflammatory cytokines and chemokines ↑
→ epithelial damage and airway inflammation.
Severe / neutrophilic asthma pathway:
NLRP3 ↑ + IL-1β ↑ + Th17 / IL-17 ↑
→ CXCL8 ↑
→ neutrophils ↑
→ persistent inflammation and corticosteroid resistance.
Airway-remodeling pathway:
Chronic inflammation
→ TGF-β1 / SMAD2 / SMAD3 ↑
→ collagen deposition ↑ + VEGF ↑ + MMP-9 dysregulation
→ subepithelial fibrosis + airway-wall thickening +
smooth-muscle hypertrophy
→ persistent airflow limitation.
Most Important Targets for Product / Mechanism Screening
For screening natural products or other interventions for potential relevance
to asthma, the highest-priority targets are:
IL-4, IL-5, IL-13, IL-33, ST2 / IL1RL1, ILC2, TSLP, IgE,
FcεRI, 5-LOX / ALOX5, CysLT1, NF-κB, TGF-β1,
ROS, Nrf2, IL-17, CXCL8, and NLRP3.
| Inhaler / Drug Class |
Examples |
Main Pathway / Target |
Direction |
Main Effect |
| SABA (Short-Acting β2-Agonist) |
Salbutamol / Albuterol, Terbutaline |
β2-adrenergic receptor → Gs → Adenylyl Cyclase → cAMP → PKA |
↑ |
Rapid airway smooth-muscle relaxation and bronchodilation; used for acute symptom relief. |
| LABA (Long-Acting β2-Agonist) |
Formoterol, Salmeterol |
β2-adrenergic receptor → cAMP / PKA |
↑ |
Prolonged bronchodilation and reduced bronchoconstriction. In asthma, generally used with an inhaled corticosteroid. |
| ICS (Inhaled Corticosteroid) |
Budesonide, Fluticasone, Beclomethasone, Mometasone |
Glucocorticoid Receptor / NR3C1 |
↑ |
Activates anti-inflammatory glucocorticoid signaling and suppresses chronic airway inflammation. |
| ICS (Inhaled Corticosteroid) |
Budesonide, Fluticasone, Beclomethasone, Mometasone |
NF-κB |
↓ |
Reduces transcription of inflammatory cytokines, chemokines, and other inflammatory mediators. |
| ICS (Inhaled Corticosteroid) |
Budesonide, Fluticasone, Beclomethasone, Mometasone |
AP-1 |
↓ |
Suppresses inflammatory gene transcription. |
| ICS (Inhaled Corticosteroid) |
Budesonide, Fluticasone, Beclomethasone, Mometasone |
IL-4 / IL-5 / IL-13 |
↓ |
Reduces Type-2 inflammation, eosinophilic inflammation, mucus production, and airway hyperresponsiveness. |
| ICS / LABA Combination |
Budesonide/Formoterol, Fluticasone/Salmeterol, Fluticasone/Vilanterol |
Glucocorticoid Receptor |
↑ |
Suppresses airway inflammation. |
| ICS / LABA Combination |
Budesonide/Formoterol, Fluticasone/Salmeterol, Fluticasone/Vilanterol |
β2-adrenergic receptor → cAMP / PKA |
↑ |
Provides prolonged bronchodilation while the corticosteroid controls inflammation. |
| SAMA (Short-Acting Muscarinic Antagonist) |
Ipratropium |
M3 Muscarinic Receptor |
↓ |
Reduces cholinergic airway smooth-muscle contraction and decreases bronchoconstriction. |
| SAMA (Short-Acting Muscarinic Antagonist) |
Ipratropium |
Gq → PLC → IP3 → intracellular Ca2+ |
↓ |
Reduces intracellular calcium signaling required for airway smooth-muscle contraction. |
| LAMA (Long-Acting Muscarinic Antagonist) |
Tiotropium, Glycopyrronium, Umeclidinium |
M3 Muscarinic Receptor |
↓ |
Produces prolonged inhibition of cholinergic bronchoconstriction and can improve airflow control. |
| ICS / LABA / LAMA Triple Therapy |
Fluticasone Furoate / Umeclidinium / Vilanterol |
Glucocorticoid Receptor |
↑ |
Suppresses airway inflammation. |
| ICS / LABA / LAMA Triple Therapy |
Fluticasone Furoate / Umeclidinium / Vilanterol |
β2-adrenergic receptor → cAMP / PKA |
↑ |
Promotes airway smooth-muscle relaxation and bronchodilation. |
| ICS / LABA / LAMA Triple Therapy |
Fluticasone Furoate / Umeclidinium / Vilanterol |
M3 Muscarinic Receptor |
↓ |
Blocks cholinergic bronchoconstriction and provides additional bronchodilation. |
Simplified pathway summary:
β2-Agonists:
β2-AR ↑ → Adenylyl Cyclase ↑ → cAMP ↑ →
PKA ↑ → airway smooth-muscle contraction ↓ →
bronchodilation ↑.
Inhaled Corticosteroids:
Glucocorticoid Receptor ↑ →
NF-κB ↓ + AP-1 ↓ →
IL-4 / IL-5 / IL-13 ↓ →
eosinophilic airway inflammation ↓.
Muscarinic Antagonists:
M3 Receptor ↓ →
Gq / PLC / IP3 / Ca2+ signaling ↓ →
airway smooth-muscle contraction ↓ →
bronchodilation ↑.
|