The CysLT1 Ligand Leukotriene D4 Supports α4β1- and α5β1-Mediated Adhesion and Proliferation of CD34+ Hematopoietic Progenitor Cells

Abstract

Cytokines and chemokines control hematopoietic stem and progenitor cell (HPC) proliferation and trafficking. However, the role of nonpeptide mediators in the bone marrow microenvironment has remained elusive. Particularly CysLT1, a G protein-coupled receptor recognizing inflammatory mediators of the cysteinyl leukotriene family, is highly expressed in HPCs. We therefore analyzed the effects of its ligands on human CD34+ HPCs. The most potent CysLT1 ligand, LTD4, rapidly and significantly up-regulated α4β1 and α5β1 integrin-dependent adhesion of both primitive and committed HPC. LTD4-triggered adhesion was inhibited by specific CysLT1 antagonists. The effects of other CysLT1 ligands were weak (LTC4) or absent (LTE4). In serum-free liquid cultures supplemented with various hematopoietic cytokines including IL-3, only LTD4 significantly augmented the expansion of HPCs in a dose-dependent manner comparable to that of peptide growth factors. LTC4 and LTE4 were less effective. In CD34+ cell lines and primary HPCs, LTD4 induced phosphorylation of p44/42 ERK/MAPK and focal adhesion kinase-related tyrosine kinase Pyk2, which is linked to integrin activation. Bone marrow stromal cells produced biologically significant amounts of cysteinyl leukotrienes only when hematopoietic cells were absent, suggesting a regulatory feedback mechanism in the hematopoietic microenvironment. In contrast to antagonists of the homing-related G protein-coupled receptor CXCR4, administration of a CysLT1 antagonist failed to induce human CD34+ HPC mobilization in vivo. Our results suggest that cysteinyl leukotriene may contribute to HPC retention and proliferation only when cysteinyl leukotriene levels are increased either systemically during inflammation or locally during marrow aplasia.

International Union of Basic and Clinical Pharmacology. LXXXIV: Leukotriene Receptor Nomenclature, Distribution, and Pathophysiological Functions

“…Furthermore, in Caco-2 cells, LTD 4 controlled adhesive properties and migration by up-regulating COX-2 and stimulating PGE 2 -induced expression of ␣2␤1 integrins (Massoumi et al, 2003). In another study, LTD 4 was demonstrated to rapidly induce focal adhesion kinase-related tyrosine kinase phosphorylation and significantly up-regulated ␣4␤1 and ␣5␤1 integrin-dependent adhesion of both primitive and committed hematopoietic stem and progenitor cell (Boehmler et al, 2009).…”

“…CysLT 1 Rs are also found to be expressed in B lymphocytes and CD34 ϩ hematopoietic progenitor cells . Indeed, early observations demonstrated that LTD 4 -stimulate chemotaxis and transendothelial migration of CD34 ϩ hematopoietic progenitor cells (Bautz et al, 2001;Mohle et al, 2003) as well as their proliferation (Braccioni et al, 2002;Parameswaran et al, 2004;Boehmler et al, 2009) and that these activities were suppressed by different CysLT 1 receptor antagonists. Altogether these data indicate a physiological role for cysteinyl LTs as autocrine regulators of hematopoiesis corroborated by the expression of LTC 4 S in immature myeloid cells (Tornhamre et al, 2003).…”

Eicosanoid regulation of hematopoiesis and hematopoietic stem and progenitor trafficking

“…It is also a potent chemoattractant for polymorphonuclear leukocytes and regulates transendothelial migration (128, 129), which is at least partially mediated by regulation of adhesion molecules. While LTB 4 can induce migration of mature blood cells, only the cysteinyl leukotriene LTD 4 can induce chemotaxis and transendothelial migration of CD34 + progenitors (130), which is mediated in part by regulation of VLA-4 and VLA-5 adhesion (131). However, in vivo treatment with a LTD 4 receptor antagonist does not result in mobilization of CD34 + cells (131) possibly due to low baseline levels of LTD 4 in steady state bone marrow.…”

Molecular Mechanisms Underlying Bone Marrow Homing of Hematopoietic Stem Cells

“…However, to a lesser extent, also other chemokines and cytokines, including CCL2 (MCP-1), CCL5 (RANTES), CXCL10 (IP-10), IL-8 and SCF could also induce transendothelial migration (Liesveld et al, 2001). In addition, LTD4, a ligand for CysLT(1), a G protein-coupled receptor recognizing inflammatory mediator of the cysteinyl leukotriene family, which is highly expressed in hematopoietic progenitors, has been demonstrated to up-regulate CD49d/CD29 and CD49e/CD29 dependent adhesion of hematopoietic progenitors (Boehmler et al, 2009) and to induce chemotaxis and in vitro transendothelial migration (Bautz et al, 2001). Recently, a role for the proteolysis-resistant bioactive lipids sphingosine-1-phosphate and ceramide-1-phosphate in regulation of bone marrow homing has been suggested.…”