To help understand the role of chemokines in NK cell trafficking, we determined the chemokine receptor profiles of three different human NK cell lines and freshly isolated primary human NK cells. The cell lines overlapped in their chemokine receptor profiles: CXCR3 and CXCR4 were expressed by all three lines, whereas CCR1, CCR4, CCR6, CCR7, and CX3CR1 were expressed by only one or two of the lines, and no other chemokine receptors were detected. Freshly isolated primary NK cells were found to express CXCR1, CXCR3, and CXCR4, and to contain subsets expressing CCR1, CCR4, CCR5, CCR6, CCR7, CCR9, CXCR5, and CXCR6. With the exception of CCR4, these chemokine receptors were expressed at higher percentages by CD56bright NK cells than by CD56dim NK cells. In particular, CCR7 was expressed by almost all CD56bright NK cells but was not detected on CD56dim NK cells. CCR9 and CXCR6 have not been described previously on primary NK cells. These results indicate that within both the CD56bright and CD56dim NK cell populations, subsets with the capacity for differential trafficking programs exist, which likely influence their functions in innate and adaptive immunity.

The chemokine system represents a diverse group of G proteincoupled receptors responsible for orchestrating cell recruitment under both homeostatic and inflammatory conditions. Chemokine receptor 9 (CCR9) is a chemokine receptor known to be central for migration of immune cells into the intestine. Its only ligand, CCL25, is expressed at the mucosal surface of the intestine and is known to be elevated in intestinal inflammation. To date, there are no reports of small-molecule antagonists targeting CCR9. We report, for the first time, the discovery of a small molecule, CCX282-B, which is an orally bioavailable, selective, and potent antagonist of human CCR9. CCX282-B inhibited CCR9-mediated Ca 2ϩ mobilization and chemotaxis on Molt-4 cells with IC 50 values of 5.4 and 3.4 nM, respectively. In the presence of 100% human serum, CCX282-B inhibited CCR9-mediated chemotaxis with an IC 50 of 33 nM, and the addition of ␣1-acid glycoprotein did not affect its potency. CCX282-B inhibited chemotaxis of primary CCR9-expressing cells to CCL25 with an IC 50 of 6.8 nM. CCX282-B was an equipotent inhibitor of CCL25-directed chemotaxis of both splice forms of CCR9 (CCR9A and CCR9B) with IC 50 values of 2.8 and 2.6 nM, respectively. CCX282-B also inhibited mouse and rat CCR9-mediated chemotaxis. Inhibition of CCR9 with CCX282-B results in normalization of Crohn's disease such as histopathology associated with the TNF ⌬ARE mice. Analysis of the plasma level of drug associated with this improvement provides an understanding of the pharmacokinetic/ pharmacodynamic relationship for CCR9 antagonists in the treatment of intestinal inflammation.

Abstract. Metastatic breast cancer is the leading cause of cancer-related death in women worldwide and, despite recent therapeutic advances, the disease remains incurable. A critical step in cancer cell metastasis is the degradation of extracellular matrix components by matrix metalloproteinases (MMPs), which permits malignant cells to separate from the primary tumor and access circulatory conduits for seeding distant organs. This study reports a correlation between the elevated secretion of MMP-3 by breast cancer cells and the expression of CCR7 protein, a recently discovered non-classical chemokine receptor that may play a role in metastasis by regulating tumor cell transendothelial migration. MMP-3 secretion is increased in human mammary tumor cells that overexpress CXCR7, and is reduced in mouse breast cancer cells in which the endogenous CXCR7 expression has been knocked down via RNAi. The correlation between CXCR7 and MMP-3 expression in breast cancer may provide additional therapeutic rationale for targeting CXCR7 in order to prevent metastatic disease.

No abstract