Table 1.

Regulators involved in the recruitment of macrophages to the herniated disc

Regulator	Sample	Results	Reference
MCP-1, IL-8	Human IVD	Macrophages and capillaries have chemotaxis characteristics.	Burke et al. 2002 [60]
MCP-1, MIP-1α	Human IVD	They are overexpressed in macrophages, fibroblasts, and endothelial cells.	Haro et al. 1996 [37]
TSLP	Human and mouse IVD	Endogenous TGF-β reduces the expression of TSLP in the intervertebral disc by inhibiting NF-κB activation.	Zhu et al. 2013 [64]
RANTES, IL-1β	Human IVD	RANTES expression is upregulated by IL-1β.	Kepler et al. 2013 [65]
MCP-1	Rat IVD	MCP-1 promotes the absorption of rat nucleus pulposus tissue.	Haro et al. 2005 [66]
TSLP	Mouse IVD	TSLP induced by NF-kappaB activating ligand in the intervertebral disc may promote the recruitment of macrophages to the intervertebral disc by stimulating the production of MCP-1.	Ohba et al. 2008 [67]
MCP-1, MMP3	Mouse IVD	TNF-α induces the expression of MCP-1 and MMP-3.	Fujita et al. 2012 [68]
MMP3, MMP-7	Co-culture system of mouse chondrocytes and macrophages	MMP-3 produced by chondrocytes stimulates the production of macrophage chemoattractants.	Haro et al. 2000 [69]
TNF-α, IL-1β, CCL3	Rat IVD	TNF-α and IL-1β regulate the expression of CCL3 in nucleus pulposus cells.	Wang et al. 2013 [70]

Abbreviations: MCP-1 monocyte chemoattractant protein 1, IL interleukin, MIP-1α macrophage inflammatory protein-1 α, TSLP thymic stromal lymphopoietin, RANTES chemokine ligand 5, MMP matrix metalloproteinase, TNF-α tumor necrosis factor-α, CCL3 C-C Motif Chemokine Ligand 3