IL-17-mediated monocyte migration occurs partially through CC chemokine ligand 2/monocyte chemoattractant protein-1 induction.
Rheumatoid arthritis (RA) is a chronic inflammatory disease that is mediated, in part, by proinflammatory factors produced by RA synovial tissue (ST) fibroblasts and macrophages, resulting in monocyte migration from the blood to the ST. To characterize the potential role of IL-17 in monocyte migration, RA synovial fibroblasts and macrophages were activated with IL-17 and examined for the expression of monocyte chemokines. The two potentially important monocyte chemoattractants identified were CCL20/MIP-3alpha and CCL2/MCP-1, which were significantly induced in RA synovial fibroblasts and macrophages. However, in vivo, only CCL2/MCP-1 was detectable following adenovirus IL-17 injection. We found that IL-17 induction of CCL2/MCP-1 was mediated by the PI3K, ERK, and JNK pathways in RA ST fibroblasts and by the PI3K and ERK pathways in macrophages. Further, we show that neutralization of CCL2/MCP-1 significantly reduced IL-17-mediated monocyte recruitment into the peritoneal cavity. We demonstrate that local expression of IL-17 in ankle joints was associated with significantly increased monocyte migration and CCL2/MCP-1 levels. Interestingly, we show that RA synovial fluids immunoneutralized for IL-17 and CCL2/MCP-1 have similar monocyte chemotaxis activity as those immunoneutralized for each factor alone. In short, CCL2/MCP-1 produced from cell types present in the RA joint, as well as in experimental arthritis, may be responsible, in part, for IL-17-induced monocyte migration; hence, these results suggest that CCL2/MCP-1 is a downstream target of IL-17 that may be important in RA.
Shahrara
Shiva
S
Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. s-shahrara@northwestern.edu
Pickens
Sarah R
SR
Mandelin
Arthur M
AM
Karpus
William J
WJ
Huang
Qiquan
Q
Kolls
Jay K
JK
Pope
Richard M
RM
D000818:Animals; D000843:Ankle Joint; D001169:Arthritis, Experimental / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement / Q000276:immunology*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis* / Q000502:physiology; D002908:Chronic Disease; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D020381:Interleukin-17 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D013583:Synovial Membrane / Q000276:immunology / Q000378:metabolism / Q000473:pathology
C111835:CCL2 protein, human; C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; C508717:IL17A protein, human; C098680:Il17a protein, mouse; D020381:Interleukin-17