Table 1.

Summary of major IL-33 activities.

Function	Activity	Ref.
DAMP	signals the innate immune cells in response to stress or cell membrane disruption	[33,34]
Transcription factor	regulates the gene expression	[35,36,37,38]
Cytokine	signals the immune cells via ST2 receptor to eliminate infection and manage tissue injury (proregenerative activity)	[39,40,41,42]
	modulates the T helper 2 (Th2) lymphocytes as well as Th1 and regulatory lymphocytes	[43,44,45]
	upregulates the inflammatory response to bacterial LPS	[42]
	potentially is involved in the development of disease due to maintenance of chronic inflammation	[38,44,45,46,47,48,49,50,51]

DAMP (damage-associated molecular pattern); LPS (lipopolysaccharide); ST2 (secretory receptor, an interleukin (IL)-1 receptor family member); Th (T helper lymphocytes).