Table 1.

DAMPs and their signaling pathways are implicated in inflammation and OA pathogenesis.

DAMPs	Signaling	References
ECM compositions
Decorin and biglycan	C1q; Complement system	[19,27]
Fibronectin	TLR2, 4/JUK2-MAPK	[35]
Hyaluronan	TLR4/MyD88	[38]
Biglycan	TLR2, 4/ERK/NF-κB	[39,40]
Tenascin c	TLR4/MAPK	[41]
Syndecan-4	MAPK	[42]
Type II collagen 29-mer fragment	TLRs/NF-κB	[43,44]
Aggrecan 32-mer fragment	TLR2/NF-κB	[45]
Crystals
CPPD, BCP	TLR2/NF-κB NLR/NLRP3	[46,47]
Alarmins
HMGB1	TLR2, 4/ERK/NF-κB	[60,62]
s100sA8, S100A9	TLR4/NF-κB	[63,64]
UA	NLR/NLRP3
ATP	NLR/NLRP3	[66,67]
IL-1α	IL-1R1/MAPK	[65]
IL-33	MyD88/NF-κB/MAPK	[68,69]
FliI	TLR4/ERK1	[21]
Plasma proteins
Fibrinogen	TLR4/NF-κB	[19,27]
Gc-globulin	C5a; Complement system	[19,27]
α1-microglobulin, α2-macroglobulin	MAPK-ERK/NF-κB	[19,27]