Upregulation of Inflammatory Cytokines and Oncogenic Signal Pathways Preceding Tumor Formation in a Murine Model of T-Cell Lymphoma in Skin

Abstract

The tumor microenvironment, including its inflammatory components, regulates tumor progression. Herein, we explore the relationship between inflammation and the progression of T-cell lymphoma in the cutaneous microenvironment. Injection of MBL2 murine T lymphoma cells into ear skin of C57BL/6 and immunodeficient SCID/Beige mice resulted in tumor formation in only the latter group. However, induction of skin inflammation by one topical application of DNFB following MBL2 inoculation in C57BL/6 mice resulted in progressive high-grade lymphoma. The DNFB-regulated tumor formation was blocked by early, but not late, application of a potent topical corticosteroid. At 2 days after implantation, a 10-fold decrease in MBL2 cell apoptosis was detected in DNFB-treated ears compared with vehicle control. After DNFB treatment, Gr-1(high) neutrophils and F4/80(+) macrophages constituted the majority of tumor-infiltrating CD45(+) leukocytes. Depletion of macrophages by clodronate-containing liposomes blocked the tumor-promoting effect of DNFB. Transcriptional profiling of inflammatory cytokines and chemokines after DNFB treatment revealed robust changes in genes that are important in chemotaxis, proliferation, and apoptosis. Activation of oncogenic signal pathways, including NF-κB, was also detected. This work provides insights into the cellular and molecular pathways that mediate lymphoma progression and may have applicability to human cutaneous T-cell lymphomas.

Association of the numbers of CD163+ cells in lesional skin and serum levels of soluble CD163 with disease progression of cutaneous T cell lymphoma

“…Abrogated tumor formation by depletion of macrophages in a murine cutaneous lymphoma model also suggested a central role of macrophages in CTCL [27].…”

“…CD163 + cells were detected in the invasive margin of the tumor in CTCL patients [26]. Moreover, abundant CD163 + cells were observed intermingled among tumor cells in a murine cutaneous lymphoma model [27]. Thus, we decided to stain lesional skin of CTCL for CD163.…”

Mast cells play a protumorigenic role in primary cutaneous lymphoma

“…Besides To investigate growth of lymphomas in vivo, we chose to use subcutaneous injections of the mouse lymphoma cell line EL4, which we thought would best mimic cutaneous lymphoma in mice and which closely resembles the model of Wu et al 7 In this model, the mouse lymphoma cell line MBL2 was used instead of EL4. MBL2 and EL4 have both been shown to express a unique CTL epitope and identical TCR␣-and ␤-chains, suggesting a common origin of the 2 cell lines.…”

“…For comparison, we also analyzed tumor growth in the traditionally used mast cell-deficient C57BL/6 Kit W-sh/W-sh line, which shows several other defects in addition to the deficiency of mast cells because of a genetic conversion in the Kit gene promoter. In analogy to a recently published mouse model of CTCL, 7 we injected the mouse T-cell lymphoma cell line EL4 subcutaneously in Mcpt5-Cre ϩ /iDTR ϩ , C57BL/6 Kit W-sh/W-sh , and control mice. To also analyze microvessel density in EL4 tumors, we stained tumor samples with CD31-antibody and observed a decreased microvessel density in Mcpt5-Cre ϩ /iDTR ϩ mice ( Figure 6G) compared with WT C57BL/6 ( Figure 6E) and Mcpt5-Cre Ϫ /iDTR ϩ controls ( Figure 6F).…”

“…Involvement of immune cells is suggested by elevated levels of inflammatory cytokines in plasma and skin sections of CTCL patients, such as IL-1␤, 6 A recent study using a mouse model of CTCL reported on increased numbers of macrophages and neutrophils, and showed that tumor growth was reduced after depletion of macrophages. 7 Mast cells are bone marrow-derived hematopoietic cells that are preferentially located in tissues exposed to the environment, such as skin, airways, and gastrointestinal tract. 8,9 Because of this location, they are one of the first immune cells to interact with invading pathogens or antigens.…”