IMMUNE OSby Allerim

cytokine

IL-33

Epithelial and stromal alarmin that lowers type 2 activation thresholds

alarminepitheliumTH2mast cell

Review layer

Last reviewed 2026-05-17

well-supportedclinical context required

Alarmin pages emphasize epithelial and stromal alarm signals as threshold-lowering inputs rather than isolated cytokine facts.

3 review sources

State signature

Systems profile

Inflammation52
Tolerance45
Metabolism54
Tissue88
Neuroimmune80
Chronicity48

Cascade viewer

Source → signal → tissue behavior

Sources

epithelium
endothelium
fibroblasts
stromal cells

Signal

IL-33

Targets and effects

mast cells
ILC2
T cell subsets
epithelial alarm
mucus programs
related: IL-4related: IL-5related: IL-13related: TSLP

Graph neighborhood

Direct relationships

Full graph

Epithelial alarmin lowers mast cell activation threshold

Airway epithelial injury and alarmin release

IL-33 activates ILC2-type barrier responses with IL-5, IL-13, and amphiregulin output

Cytokine ecology

Signal Role

IL-33 is released during tissue stress and activates ST2-expressing cells such as mast cells and ILC2s, linking barrier injury to type 2 immunity.

Pathway

ST2/IL1RL1MyD88NF-kBMAPK

Source Cells

epitheliumendotheliumfibroblastsstromal cells

Target Cells

mast cellsILC2T cell subsetseosinophils

Inflammatory Role

Amplifies allergic inflammation, mucus, eosinophils, mast cell activation, and tissue repair loops.

Regulatory Role

Supports wound repair and parasite defense when transient.

Tissue Effects

epithelial alarmmucus programsfibrosis riskairway hyperreactivity

Metabolic Effects

couples tissue damage and hypoxia to type 2 repair metabolism

Nervous System Interactions

participates in itch, cough, and sensory-neuroimmune barrier circuits

Related Loops

epithelial injury -> IL-33 -> mast cell/ILC2IL-33 -> IL-5/IL-13 -> eosinophilic tissue remodeling