Human CC chemokine CCL23 enhances expression of matrix metalloproteinase-2 and invasion of vascular endothelial cells.

Human CCL23 (also known as CKbeta8, MPIF-1, or MIP-3) has been recently reported to induce endothelial cell migration and tube formation via CCR1. Matrix metalloproteinases (MMPs) are involved in the degradation of the extracellular matrix and also appear to play critical roles in angiogenesis. In the present study, we have demonstrated that CCL23 enhances the expression of MMP-2 mRNA and protein levels in endothelial cells in a dose-dependent manner, but has no effect on the expression levels of MMP-9, TIMP-1, TIMP-2, and MT1-MMP. CCL23 was shown to dose-dependently activate the expression of the MMP-2/Luc reporter gene, thereby indicating that it stimulates the transcription of the MMP-2 gene. Vascular endothelial cells, when exposed to CCL23, showed a marked ability to invade through a 3D Matrigel. This increase in invasion was also correlated with enhancements in the expression and activity of MMP-2. Neutralization with anti-CCL23 and anti-CCR1 antibodies, as well as the heat-induced inactivation of CCL23, resulted in a blockage of the CCL23-activated invasion, indicating that the invasion of HUVECs was induced by CCL23 specifically. Furthermore, we showed that the CCL23-induced invasion was inhibited by MMP inhibitors such as GM6001 and a specific MMP-2 Inhibitor I. Our results indicate that CCL23 may play a direct role in angiogenesis, via the upregulation of MMP-2 expression.

Human CC chemokine CCL23, a ligand for CCR1, induces endothelial cell migration and promotes angiogenesis.

A number of chemokines induce angiogenesis and endothelial cells express several chemokine receptors. To date, only a limited number of CC chemokines for CCR1 have been reported to induce angiogenic responses. We investigated the ability of CCL23 (also known as MPIF-1, MIP-3, or CKbeta8) to promote angiogenesis, which induces chemotaxis of immune cells through CCR1. CCL23 promoted the chemotactic migration and differentiation of endothelial cells, and neovascularization in the chick chorioallantoic membrane. An N-terminal truncated form of CCL23 was at least 100-fold more potent than its intact form and was comparable to that of FGF in the angiogenic activities. Treatment with either pertussis toxin or anti-CCR1 antibody completely inhibited the CCL23-induced endothelial cell migration, indicating that endothelial cell migration was mediated through CCR1. CCL23 didn't promote the migration of HT1080 human fibrosarcoma cells that did not express CCR1. Our results suggest a role of CCL23 in angiogenesis in vitro as well as in vivo.

PLP2/A4 interacts with CCR1 and stimulates migration of CCR1-expressing HOS cells.

Multiple CC chemokines bind to CCR1, which plays important roles in immune and inflammatory responses. To search for proteins involved in the CCR1 signaling pathway, we screened a yeast two-hybrid library using the cytoplasmic tail of CCR1 as the bait. One of the positive clones contained an open reading frame of 456bp, of which the nucleotide sequence was identical to that of proteolipid protein 2 (PLP2), also known as protein A4. Mammalian two-hybrid and coimmunoprecipitation analyses demonstrated the association of PLP2/A4 with CCR1. Indirect immunofluorescence analysis revealed that PLP2/A4 was predominantly located in plasma membrane and colocalized with CCR1 in transfected human HEK293 cells. In addition, focal staining of CCR1 appeared on the periphery of the membrane upon short exposure to Leukotactin-1(Lkn-1)/CCL15, a CCR1 agonist, and was costained with PLP2/A4 on the focal regions. PLP2/A4 mRNAs were detected in various cells such as U-937, HL-60, HEK293, and HOS cells. Overexpression of PLP2/A4 stimulated a twofold increase in the agonist-induced migration of HOS/CCR1 cells, implicating a functional role for PLP2/A4 in the chemotactic processes via CCR1.

Angiogenic activity of human CC chemokine CCL15 in vitro and in vivo.

CCL15 is a novel human CC chemokine and exerts its biological activities on immune cells through CCR1 and CCR3. Because a number of chemokines induce angiogenesis and endothelial cells express CCR1 and CCR3, we investigated the angiogenic activity of CCL15. Both CCL15(1-92) and N-terminal truncated CCL15(25-92) stimulate the chemotactic endothelial cell migration and differentiation, but CCL15(25-92) is at least 100-fold more potent than CCL15(1-92). Treatment with pertussis toxin (PTX), with anti-CCR1, or with anti-CCR3 antibody inhibits the CCL15(25-92)-induced endothelial cell migration. CCL15(25-92) also stimulates sprouting of vessels from aortic rings and mediates angiogenesis in the chick chorioallantoic membrane assay. Our findings demonstrate that CCL15(25-92) has in vitro and in vivo angiogenic activity, and suggest roles of the chemokine in angiogenesis.