title: Synergy between coproduced CC and CXC chemokines in monocyte chemotaxis through receptor-mediated events.
abstract: CC and CXC chemokines coinduced in fibroblasts and leukocytes by cytokines and microbial agents determine the number of phagocytes infiltrating into inflamed tissues. Interleukin-8/CXCL8 and stromal cell-derived factor-1/CXCL12 significantly and dose-dependently increased the migration of monocytes, expressing the corresponding CXC chemokine receptors CXCR2 and CXCR4, toward suboptimal concentrations of the monocyte chemotactic proteins CCL2 or CCL7. These findings were confirmed using different chemotaxis assays and monocytic THP-1 cells. In contrast, the combination of two CC chemokines (CCL2 plus CCL7) or two CXC chemokines (CXCL8 plus CXCL12) did not provide synergy in monocyte chemotaxis. These data show that chemokines competing for related receptors and using similar signaling pathways do not synergize. Receptor heterodimerization is probably not essential for chemokine synergy as shown in CXCR4/CCR2 cotransfectants. It is noteworthy that CCL2 mediated extracellular signal-regulated kinase 1/2 phosphorylation and calcium mobilization was significantly enhanced by CXCL8 in monocytes, indicating cooperative downstream signaling pathways during enhanced chemotaxis. Moreover, in contrast to intact CXCL12, truncated CXCL12(3-68), which has impaired receptor signaling capacity but can still desensitize CXCR4, was unable to synergize with CCL2 in monocytic cell migration. Furthermore, AMD3100 and RS102895, specific CXCR4 and CCR2 inhibitors, respectively, reduced the synergistic effect between CCL2 and CXCL12 significantly. These data indicate that for synergistic interaction between chemokines binding and signaling of the two chemokines via their proper receptors is necessary.
authors.affiliation: Laboratory of Molecular Immunology, Rega Institute, University of Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Mieke
authors.initials: M
authors.lastname: Gouwy
authors.forename: Sofie
authors.initials: S
authors.lastname: Struyf
authors.forename: Samuel
authors.initials: S
authors.lastname: Noppen
authors.forename: Evemie
authors.initials: E
authors.lastname: Schutyser
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Springael
authors.forename: Marc
authors.initials: M
authors.lastname: Parmentier
authors.forename: Paul
authors.initials: P
authors.lastname: Proost
authors.forename: Jo
authors.initials: J
authors.lastname: Van Damme
mesh_terms: D000818:Animals; D016466:CHO Cells; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology; D054410:Chemokine CCL7 / Q000096:biosynthesis / Q000502:physiology; D054377:Chemokine CXCL12 / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D002634:Chemotaxis, Leukocyte / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D009000:Monocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000502:physiology; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors / Q000502:physiology; D023063:Receptors, Interleukin-8B / Q000037:antagonists & inhibitors / Q000502:physiology
chemical_list: C111835:CCL2 protein, human; C515450:CCL7 protein, human; C515255:CXCL12 protein, human; C508606:CXCL8 protein, human; C527276:CXCR4 protein, human; D018932:Chemokine CCL2; D054410:Chemokine CCL7; D054377:Chemokine CXCL12; D016209:Interleukin-8; D010446:Peptide Fragments; D019718:Receptors, CXCR4; D023063:Receptors, Interleukin-8B