Table 5.

Anti-inflammatory effects and mechanisms of IL-37 in autoimmune diseases.

Disease	Expression status	Cells	Model	Mechanism	Reference
Inflammatory bowel disease	aColonic mucosa↑ bSerum ↓	No	Colitis hIL-37tg mice	↑IL-10 ↓IL-1β ↓TNF-α ↓T cells ↓DCs	[53–56]
Systemic lupus erythematosus	cSerum/PBMC ↑	PBMCs	No	↓TNF-α ↓IL-6 ↓IL-1β	[58, 59]
Rheumatoid arthritis	dSynovial tissue/ plasma/PBMC ↑	PBMCs and naive CD4+ T cells	Collagen-induced arthritis mice	↓IL-17 ↓IL-1b ↓ IL-6 ↓Th17 cells	[61–64]
Psoriasis	ePsoriatic lesion↑	Keratinocyte cells	K14-VEGF-Tg mice	↓IFN-γ ↓CXCL8 ↓IL-6 ↓S100A7	[68]
Asthma	fPBMC/Serum/Induced sputum cells↓	Induced sputum cells	Ovalbumin-induced asthma mice	↓IL-1β ↓IL-6 ↓TNF-α↓IL-17	[70, 71]
Guillain-Barre syndrome	gCerebrospinal fluid/Plasma↑	Cerebrospinal fluid and plasma cells	No	Unknown	[72]
Ankylosing spondylitis	cSerum/PBMC↑	PBMCs	No	↓TNF-α ↓IL-6 ↓IL-17 ↓IL-23	[73]
Graves' disease	cSerum/PBMC ↑	PBMCs	No	↓IL-6 ↓IL-17 ↓TNF-α	[74]

PBMC: peripheral blood mononuclear cell. DCs: dendritic cells. ↑: upregulate. ↓: downregulate. ^aLevels of IL-37 in colonic mucosa were increased. ^bLevels of IL-37 in serum were reduced. ^cExpression of IL-37 in both serum and PBMC was increased. ^dExpression of IL-37 in synovial tissue, plasma, and PBMC was elevated. ^eLevels of IL-37 in psoriatic lesion were upregulated. ^fLevels of IL-37 in PBMC, serum, and induced sputum cells were downregulated. ^gExpression of IL-37 in both cerebrospinal fluid and plasma was increased.