. 2021 Sep 24;61(3):913–925. doi: 10.1093/rheumatology/keab721

Table 1.

Synovial myeloid cell heterogeneity (based on [17])

Markers defining this population			Associated with inflammation/ remission	Possible function, associated expression profile	Mouse equivalent (Culemann et al. 2019)
MerTK^pos	TREM2^pos	TREM2^low	Increased in early undifferentiated arthrits	May represent early activated TREM2^high
		TREM2^high	Remission	Restraining inflammation; expression associated with complement and defensin pathways, Treg differentiation, restriction of effector T-cell function, scavenger receptor etc.	lining Trem2^pos Cx3cr1^pos
	FOLR2^pos	ID2^pos	Similar abundance in all conditions	May represent in situ precursors of resident macrophages
		LYVE1^pos	Remission	Immuno-regulation; gene expression associated with collagen turnover, antiprotease enzymes, coagulation factors and regulators of vascular endothelial growth factor	RELMα+ sublining mph
		ICAM1^pos	Similar abundance in all conditions	May represent first-line defence against pathogens; high expression of proinflammatory cytokine genes
MerTK^neg	HLA^pos	ISG15^pos CLEC10A^low		Interferon signalling
		CLEC10A^high HLA^high	Similar abundance in all conditions	May represent synovial tissue-resident antigen-presenting cells
	CD48^pos	S100A12^pos	Inflammation	Proinflammatory phenotype; expression of alarmin S100A9 correlated with disease severity
		SPP1^pos CD9^pos	Inflammation	Proinflammatory phenotype; osteopontin expression correlated with disease severity