Role of the S100 protein family in rheumatoid arthritis

Table 1 The expression of S100 protein family in RA

S100	Expression cells	Trend	Function	Receptors	Reference
S100A4	T cells, neutrophils, phagocytes, mast cell chondrocyte.	Serum level ↑	•Induce monocytes to produce proinflammatory cytokines	TLR4, IL-10R, RAGE, CD36	[12,13,14,15]
			•Mediates the recruitment and chemotaxis of macrophages
			•Leads to the increase of MMMP13 and promotes cartilage degradation
S100A7	Epithelial cells	no data	•The substrate of transglutaminase	RAGE	[10]
S100A8 S100A9	Monocytes, granulocytes, macrophages Osteoclast and fibroblast synovial cells Epithelial cells, endothelial cells	Synovial tissue ↑ Synovial fluid ↑ Serum level ↑	•Promote chemotaxis of macrophages and neutrophils	TLR4, RAGE	[16,17,18]
			•Endothelial cells, phagocytes, and osteoclasts are activated
			•Increased cellular inflammation
			•IL-6 expression of RA FLS is upregulated
			•Induce Th7 cell differentiation
S100A11	Ubiquitous expression in various tissues	Synovial fluid ↑ Serum level ↑	•Promote leukocyte chemotaxis and inflammation	RAGE	[19]
S100A12	Granulocytes and monocytes	Serum level ↑	•Recruitment of neutrophils and macrophages	TLR4, RAGE	[20,21,22]
S100A12	Granulocytes and monocytes	Serum level ↑	•RAGE and TLR4 receptors were activated to induce the expression of IL-1β, IL-6, and TNF-α	TLR4, RAGE	[20,21,22]
S100B	Chondrocytes, dendritic cells, lymphocytes	No data	•Promote cartilage breakdown	RAGE	[23]

ISSN: 1478-6362