CpG stimulation of chronic lymphocytic leukemia cells induces a polarized cell shape and promotes migration in vitro and in vivo.

Maria Dampmann,Bernd Giebel,Jan Dürig,Ulrich Dührsen,Florian Murke,André Görgens,Michael Möllmann,Francesco Bertolini

doi:10.1371/journal.pone.0228674

Maria Dampmann, Bernd Giebel + Show 6 more

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https://doi.org/10.1371/journal.pone.0228674

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Abstract

In order to accomplish their physiological functions leukocytes have the capability to migrate. As a prerequisite they need to adopt a polarized cell shape, forming a leading edge at the front and a uropod at rear pole. In this study we explored the capability of chronic lymphocytic leukaemia (CLL) cells to adopt this leukocyte-specific migration phenotype. Furthermore, we studied the impact of the Toll-like receptor 9 (TLR9) agonists CpGs type A, B and C and the antagonist oligodesoxynucleotide (ODN) INH-18 on the cell polarization and migration process of primary human CLL cells. Upon cultivation, a portion of purified CLL cells adopted polarized cell shapes spontaneously (range 10–38%). Stimulation with CpG ODNs type B (ODN 2006) and CpGs type C (ODN 2395) significantly increased the frequency of morphologically polarized CLL cells, while ODN INH-18 was hardly able to act antagonistically. Like in human hematopoietic stem and progenitor cells, in morphologically polarized CLL cells CXCR4 was redistributed to the leading edge and CD50 to the uropod. Coupled to the increased frequencies of morphologically polarized cells, CpGs type B and C stimulated CLL cells showed higher migration activities in vitro and following intravenous injection higher homing frequencies to the bone marrow of immunocompromised NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Thus, presumably independent of TLR-9 signaling, CpGs type B and C promote the cellular polarization process of CLL cells and their ability to migrate in vitro and in vivo.

Highlights

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the western hemisphere
All performed in duplicates, significantly higher frequencies of morphologically polarized CLL cells were detected in cultures supplemented with 0.25 μM CpGs type B or C than in corresponding control cultures not being supplemented with any CpG molecules (Fig 1C and 1D)
Whether CLL cells adopt the leukocyte/hematopoietic stem and progenitor cells (HSPCs) specific cell polarity phenotype, we studied the subcellular localization of CD50 and CXCR4, which we used as uropod and leading edge markers, respectively, in CpGs type B stimulated CLL cells exemplarily

Summary

Introduction

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the western hemisphere. Bcl-2 participates in mediating chemotherapy resistance and worsens the clinical outcome [1]. It has been selected as a target for anti-CLL therapy. Despite the positive effects of oblimersen, these studies did not investigate whether oblimersen affects the survival of CLL cells directly by the down-regulation of its target gene bcl-2 or indirectly by exerting immune stimulatory effects. In 2001, Jahrsdorfer and colleagues reported CG dinucleotides contained in oblimersen exert the same anti-CLL effects than CpG oligonucleotides, which induce the expression of costimulatory and antigen-presenting molecules on normal as well as malignant B-cells [5]. It appears more likely that oblimersen does not affect the activity of bcl-2, but like CpG motifs of bacterial DNA activates the mammalian immune system via toll-like receptor 9 signaling (TLR9) [6]

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