IL-33

IL-33 is a proinflammatory protein that may also regulate gene transcription. IL-33 was identified based on sequence and structural homology with IL-1 family cytokines and is constitutively expressed in smooth muscle and airway epithelia. It is upregulated in arterial smooth muscle, dermal fibroblasts, and keratinocytes following IL-1alpha or IL-1 beta stimulation. Similar to IL-1, IL-33 can be cleaved in vitro by caspase-1, generating an N-terminal fragment that is slightly shorter than the C-terminal fragment. The N-terminal portion of full length IL-33 contains a predicted bipartite nuclear localization sequence and a homeodomain-like helix-turn-helix DNA binding domain.