Chemokine receptor expression by leukemic T cells of cutaneous T-cell lymphoma: clinical and histopathological correlations

C-C Chemokine Receptor 7 in Cancer

C-C chemokine receptor 7 (CCR7) was one of the first two chemokine receptors that were found to be upregulated in breast cancers. Chemokine receptors promote chemotaxis of cells and tissue organization. Since under homeostatic conditions, CCR7 promotes migration of immune cells to lymph nodes, questions immediately arose regarding the ability of CCR7 to direct migration of cancer cells to lymph nodes. The literature since 2000 was examined to determine to what extent the expression of CCR7 in malignant tumors promoted migration to the lymph nodes. The data indicated that in different cancers, CCR7 plays distinct roles in directing cells to lymph nodes, the skin or to the central nervous system. In certain tumors, it may even serve a protective role. Future studies should focus on defining mechanisms that differentially regulate the unfavorable or beneficial role that CCR7 plays in cancer pathophysiology, to be able to improve outcomes in patients who harbor CCR7-positive cancers.

CCR7 in Blood Cancers - Review of Its Pathophysiological Roles and the Potential as a Therapeutic Target

According to the classical paradigm, CCR7 is a homing chemokine receptor that grants normal lymphocytes access to secondary lymphoid tissues such as lymph nodes or spleen. As such, in most lymphoproliferative disorders, CCR7 expression correlates with nodal or spleen involvement. Nonetheless, recent evidence suggests that CCR7 is more than a facilitator of lymphatic spread of tumor cells. Here, we review published data to catalogue CCR7 expression across blood cancers and appraise which classical and novel roles are attributed to this receptor in the pathogenesis of specific hematologic neoplasms. We outline why novel therapeutic strategies targeting CCR7 might provide clinical benefits to patients with CCR7-positive hematopoietic tumors.

Novel Immunotherapies for T Cell Lymphoma and Leukemia

PURPOSE OF REVIEW

Novel immunotherapies such as checkpoint inhibitors, bispecific antibodies, and chimeric antigen receptor T cells are leading to promising responses when treating solid tumors and hematological malignancies. T cell neoplasms include leukemia and lymphomas that are derived from T cells and overall are characterized by poor clinical outcomes. This review describes the rational and preliminary results of immunotherapy for patients with T cell lymphoma and leukemia.

RECENT FINDINGS

For T cell neoplasms, despite significant research effort, only few agents, such as monoclonal antibodies and allogeneic stem cell transplantation, showed some clinical activity. One of the major hurdles to targeting T cell neoplasms is that activation or elimination of T cells, either normal or neoplastic, can cause significant toxicity. A need to develop novel safe and effective immunotherapies for T cell neoplasms exists. In this review, we will discuss the rationale for immunotherapy of T cell leukemia and lymphoma and present the most recent therapeutic approaches.

Vorinostat and Mithramycin A in combination therapy as an interesting strategy for the treatment of Sézary T lymphoma: a transcriptomic approach

SAHA (vorinostat) is a histone deacetylase inhibitor approved by the USA Food and Drug Administration (FDA) for treating advanced refractory cutaneous T cell lymphomas. As SAHA alters the expression of many genes under control of the Sp1 transcription factor, we examined the effect of its association with the FDA-approved anticancer antibiotic Mithramycin A (MTR, plicamycin), a competitive inhibitor of Sp1 binding to DNA. Sézary syndrome (SS) cells, expanded ex vivo from peripheral blood mononuclear cells of 4 patients, were tested for their sensitivity to the drugs regarding cytotoxicity and differential responsive gene expression. Multivariate statistical methods were used to identify genes whose expression is altered by SAHA, MTR, and the synergist effect of the two drugs. MTR, like SAHA, induced the apoptosis of SS cells, while the two drugs in combination showed clear synergy or potentiation. Expression data stressed a likely important role of additive or synergistic epigenetic modifications in the combined effect of the two drugs, while direct inhibition of Sp1-dependent transcription seemed to have only limited impact. Ontological analysis of modified gene expression suggested that the two drugs, either independently or synergistically, counteracted many intertwined pro-survival pathways deregulated in SS cells, resistance of these tumors to intrinsic and extrinsic apoptosis, abnormal adhesion migration, and invasive properties, as well as immunosuppressive behavior. Our findings provide preliminary clues on the individual and combined effects of SAHA and MTR in SS cells and highlight a potential therapeutic interest of this novel pair of drugs for treatment of SS patients.

Sézary Syndrome and Atopic Dermatitis: Comparison of Immunological Aspects and Targets

Sézary syndrome (SS), an aggressive form of erythrodermic pruritic cutaneous T cell lymphoma (CTCL), from an immunological perspective characterized by increased Th2 cytokine levels, elevated serum IgE and impaired cellular immunity. Not only the clinical appearance but also the hallmark immunological characteristics of SS often share striking similarities with acute flares of atopic dermatitis (AD), a common benign chronic inflammatory skin disease. Given the overlap of several immunological features, the application of similar or even identical therapeutic approaches in certain stages of both diseases may come into consideration. The aim of this review is to compare currently accepted immunological aspects and possible therapeutic targets in AD and SS.

Mycosis fungoides and Sézary syndrome: Role of chemokines and chemokine receptors

Mycosis fungoides is the most common form of cutaneous T-cell lymphoma (CTCL), and is characterized by a clonal expansion of malignant CD4⁺ T lymphocytes with skin-homing properties. Clinically and pathologically, mycosis fungoides can be categorized into patch, plaque and tumor stages. The clinical course of mycosis fungoides is usually chronic and indolent, but a proportion of patients may develop progressive disease with peripheral blood, lymph node and visceral organ involvement. Sézary syndrome is an aggressive leukemic form of CTCL characterized by a clonal population of malignant T cells in the peripheral blood. Various forms of skin-directed and systemic treatments are available for mycosis fungoides and Sézary syndrome. However, current treatments are generally not curative, and can only control the disease. Currently, the etiology and pathogenesis of mycosis fungoides and Sézary syndrome are not well defined. Proposed mechanisms include chronic antigenic stimulation by infectious agents, expression of specific adhesion molecules, altered cytokine production, mutations of oncogenes and tumor suppressor genes, and avoidance of apoptosis. In recent years, a number of chemokine receptors and their corresponding chemokine ligands have been found to contribute to the migration and survival of lymphoma cells in mycosis fungoides and Sézary syndrome, including CC chemokine receptor 4 (CCR4), CCR10, C-X-C chemokine receptor type 4 (CXCR4), CCR7, CCR3 and CXCR3. Since chemokines and chemokine receptors have been found to play important roles in the pathophysiology of mycosis fungoides and Sézary syndrome, they may be potentially useful targets for the development of new treatments for these diseases in the future.

Immunological milieu in mycosis fungoides and Sézary syndrome

Tumor genesis and development are driven by a combination of intrinsic events such as oncogene activation and tumor-suppressor gene inactivation, and extrinsic events that are dependent on the interaction with the stroma. Different types of growth factors, cytokines and chemokines secreted by the surrounding stromal cells are thought to play key roles in solid tumor progression. Accumulating evidence indicates that the immunological milieu plays an essential role in tumor development, not only in solid tumors, but also in hematopoietic malignancies. Understanding the interactions between tumor cells and microenvironment in mycosis fungoides (MF) and Sézary syndrome (SS) could provide a basis for the development of new treatments for these diseases that are sometimes resistant to current therapies. This article focuses on the wide variety of cell types and immunological milieus, affecting the characteristic features of MF and SS, such as skin-homing of tumor cells, T-helper type 2-dominant tumor microenvironment, accumulation of dermal dendritic cells, epidermal hyperplasia, angiogenesis and pruritus.

CCR7 expression correlates with subcutaneous involvement in mycosis fungoides skin lesions and promotes migration of mycosis fungoides cells (MyLa) through mTOR activation

BACKGROUND

The molecular pathogenesis of mycosis fungoides (MF) is currently poorly understood. The chemokine receptor CCR7 has been demonstrated to be involved in the development and progression of certain cancers, but its role in MF has rarely been investigated.

OBJECTIVES

We seek to determine whether CCR7 is expressed in MF skin lesions. In addition, we evaluate whether CCR7 plays a role in MF cell proliferation and migration, and which signaling pathways are involved.

METHODS

Immunohistochemical staining of 21 cases of MF pathology specimens with CCR7 was performed. Medical charts and pathology slides of these cases were reviewed. Surface expression of CCR7 on MyLa cells (MF cell line) and peripheral blood mononuclear cells (PBMCs) was assessed by flow cytometry. Cell proliferation and migration were evaluated with the Alamar Blue assay and transwell chemotaxis assay, respectively.

RESULTS

CCR7 was found to be expressed in 62% (13 out of 21) of MF pathology specimens, and its expression correlated with subcutaneous extension of lymphoma cells. CCR7 expression was increased on the surface of MyLa cells compared to that on PBMCs. Addition of CCL21 (CCR7 agonist) enhanced MyLa cell migration but not proliferation. The CCL21-induced MyLa cell migration was found to be mediated by the mTOR pathway.

CONCLUSIONS

CCR7 is more likely to be expressed in MF skin lesions with subcutaneous involvement. Activation of CCR7 promotes migration of MyLa cells (MF cell line) through the mTOR pathway. These findings provide new insights into the significance of CCR7 in the pathophysiology of MF.

T lymphocyte abnormalities in juvenile systemic sclerosis patients

Multi-center evaluations of pediatric patients with juvenile systemic sclerosis (jSSc) have suggested that the pathogenesis of jSSc may differ from that of systemic sclerosis (SSc) in adult patients. Therefore, we undertook to identify abnormalities in the T lymphocytes of jSSc patients and to determine if they differed from the abnormalities reported in the T lymphocytes of adult SSc patients. We identified decreases in the frequency of resting regulatory T lymphocytes and an increased frequency of CD45RA expressing effector memory (EMRA) CD4 T lymphocytes, which were characterized by an increased frequency of CCR7 protein expressing cells. Neither the increases in the EMRA subpopulation nor the increased CCR7 protein expression have been reported in adult SSc patients. The decrease in resting regulatory T lymphocytes in jSSc patients may permit the expansion of the disease initiating CD4 T lymphocytes present in the CCR7 expressing EMRA CD4 T lymphocyte subpopulation.

Discordant immunophenotypic profiles of adhesion molecules and cytokines in acute myeloid leukemia involving bone marrow and skin

We investigated the role of adhesion molecules in skin involvement by acute myeloid leukemia (AML) using immunohistochemical analysis. Ten paired cases of skin and bone marrow biopsy specimens from patients with myeloid leukemia cutis (MLC) and 15 bone marrow biopsy specimens from patients without MLC were studied with antibodies directed against CD29, CD34, CD54, CD62-L, CD183, and cutaneous lymphocyte antigen (CLA). CLA was expressed in all cases of leukemia whereas CD54 was negative within blasts. CD62-L was expressed in 4 of 10 specimens of marrow infiltrates with MLC and 6 of 10 specimens of matching skin infiltrates; in marrows without MLC, only 2 of 15 were positive. CD29 was expressed in 1 of 10 marrow infiltrate specimens with MLC and 4 of 10 matching skin infiltrate specimens; in marrows without MLC, only 1 of 15 were positive. CD183 was expressed in 1 of 10 marrow infiltrate specimens with MLC and 4 of 10 matching skin infiltrate specimens; in marrows without MLC, CD183 was negative. The gain of CD62-L, CD29, and CD183 expression in bone marrow and skin infiltrates in leukemia cutis, relative to bone marrow infiltrates of cases without MLC, suggests a role for these markers in AML homing to skin.

The novel chemokine receptor CXCR7 regulates trans-endothelial migration of cancer cells

Background

Migration of metastatic tumor cells from the bloodstream into lymph nodes is thought to be facilitated by expression of the chemokine receptors CCR7, CXCR4 and, for B cell-derived tumors, CXCR5. Expression of their respective chemokine ligands (CCL19, CCL21, CXCL12 and CXCL13) by endothelial cells inside the lymph nodes facilitates the trans-endothelial migration (TEM) of these cells through high endothelial venules into the lymph node parenchyma. It is known that CXCR7, a second CXCL12 receptor, regulates TEM of CXCR4+CXCR7+ tumor cells towards a CXCL12 source. In this study, we set out to assess the potential stimulation by CXCL12 of tumor cell TEM towards other chemokines and whether CXCR7 might be able to regulate such effects.

Methods

The human Burkitt's lymphoma cell line NC-37, which expresses CXCR4, CXCR5, CXCR7 and CCR7, was selected as a model system. TEM of these cells through a human HUVEC endothelial cell monolayer was used as the main model system for these studies. Regulation of their TEM behavior by various concentrations of the various cognate chemokines for the above-mentioned receptors, placed in either the source or target wells of modified Boyden chamber migration plates, was assessed by quantifying the number of cells migrated under each experimental condition.

Results

Exposure of CXCR4⁺CXCR7⁺ cancer cells to CXCL12 greatly potentiated their TEM towards the chemokines CCL19 and CXCL13. This CXCL12-potentiated TEM was inhibited by the second CXCR7 chemokine ligand, CXCL11, as well as CXCR7-specific small molecule antagonists and antibodies. In contrast, the CXCR4 antagonist AMD3100 was less effective at inhibiting CXCL12-potentiated TEM. Thus, CXCR7 antagonists may be effective therapeutic agents for blocking CXCL12-mediated migration of CXCR4⁺CXCR7⁺ tumor cells into lymph nodes, regardless of whether the cancer cells follow a CXCL12 gradient or whether serum CXCL12 stimulates their migration towards CCR7 and CXCR5 chemokines in the lymph nodes.

[Cutaneous lymphoma and chemokine]

The expression pattern of chemokines and chemokine receptors is specific to certain organs and cells. Therefore, chemokines are important to elucidate the mechanism of organ-specific human diseases such as cutaneous lymphoma, characterized by proliferation of clonally expanded lymphocytes in skin without detectable systemic involvement. The most popular type of cutaneous lymphoma is T cell lymphoma, including mycosis fungoides and Sezary syndrome. We have reported that CCL17, CCL27, CCL11, and CCL26 are involved in progression of these diseases. The above chemokines are highly expressed in the lesional skin and serum levels of the chemokines are elevated as the disease progressed. Moreover, CXCL9 and CXCL10 are associated with epidermotropism of tumor cells, CCL21 is important for tumor invasion to lymph nodes, and CXCL12 may explain downregulation of CD26 on the cell surface. CXCL13 expression in lymphoid follicular formation in skin and CCR3 expression on tumor cells in CD30(+) lymphoproliferative disorders are also discussed. Biologics targeting chemokines and their receptors are promising strategies for cutaneous lymphoma. Indeed, humanized anti-CCR4 monoclonal antibody showed potent antitumor activity against CCR4(+) lymphoma cells both in vitro and ex vivo. This antibody may also be useful for allergic diseases such as hay fever. Further study on chemokines and chemokine receptors will be helpful for new classification of cutaneous lymphoma, elucidation of pathogenesis, and development of new therapeutic strategies.

IL-2-controlled expression of multiple T cell trafficking genes and Th2 cytokines in the regulatory T cell-deficient scurfy mice: implication to multiorgan inflammation and control of skin and lung inflammation

Scurfy (Sf) mice bear a mutation in the Foxp3 transcription factor, lack regulatory T cells (Treg), develop multiorgan inflammation, and die prematurely. The major target organs affected are skin, lungs, and liver. “Sf mice lacking the Il2 gene (Sf.Il2–/–), despite being devoid of Treg, did not develop skin and lung inflammation, but the inflammation in liver remained [corrected]. Genome-wide microarray analysis revealed hundreds of genes that were differentially regulated among Sf, Sf.Il2(-/-), and B6 CD4(+) T cells, but the most significant changes were those encoding receptors for trafficking/chemotaxis/retention and cytokines. Our study suggests that IL-2 controls the skin and lung inflammation in Sf mice in an apparent "organ-specific" manner through two novel mechanisms: by regulating the expression of genes encoding a variety of receptors for T cell trafficking/chemotaxis/retention and by regulating Th2 cell expansion and cytokine production. Thus, IL-2 is potentially a master regulator for multiorgan inflammation and an underlying etiological factor for various diseases associated with skin and lung inflammation.

Chemokines and cutaneous lymphoma

Chemokines are small molecules of 8-10kDa that induce chemotaxis and activation of certain subsets of leukocytes. It has been recently shown that chemokines have broader function such as inhibition of apoptosis of target cells. The expression patterns of chemokines and chemokine receptors are specific to certain organs and cells. Therefore, chemokines are important to elucidate the mechanism of organ-specific human diseases. Primary cutaneous lymphomas are characterized by proliferation of clonally expanded lymphocytes in skin, but without detectable systemic involvement at the first diagnosis. Many chemokines are reported to be expressed in lesional skin of cutaneous lymphoma. Moreover, tumor cells of a certain group of cutaneous lymphoma express limited numbers of chemokine receptors, suggesting that interactions between chemokines and their receptors may explain skin-tropism of these types of lymphoma. This article focuses on chemokines expressed in lesional skin of cutaneous lymphoma and discusses their possible roles in disease progression.

C-C chemokine receptor 1 expression in human hematolymphoid neoplasia

Chemokine receptor 1 (CCR1) is a G protein-coupled receptor that binds to members of the C-C chemokine family. Recently, CCL3 (MIP-1alpha), a high-affinity CCR1 ligand, was identified as part of a model that independently predicts survival in patients with diffuse large B-cell lymphoma (DLBCL). However, the role of chemokine signaling in the pathogenesis of human lymphomas is unclear. In normal human hematopoietic tissues, we found CCR1 expression in intraepithelial B cells of human tonsil and granulocytic/monocytic cells in the bone marrow. Immunohistochemical analysis of 944 cases of hematolymphoid neoplasia identified CCR1 expression in a subset of B- and T-cell lymphomas, plasma cell myeloma, acute myeloid leukemia, and classical Hodgkin lymphoma. CCR1 expression correlated with the non-germinal center subtype of DLBCL but did not predict overall survival in follicular lymphoma. These data suggest that CCR1 may be useful for lymphoma classification and support a role for chemokine signaling in the pathogenesis of hematolymphoid neoplasia.

Expression of T-plastin, FoxP3 and other tumor-associated markers by leukemic T-cells of cutaneous T-cell lymphoma

Peripheral blood cells from 28 patients with leukemic cutaneous T-cell lymphoma including 25 patients with Sezary syndrome were evaluated for expression of regulatory T-cell-associated markers (FoxP3, CD25, CTLA-4, neurophilin-1), T-cell activation markers (CD28 and its ligands B7.1 and B7.2) and NK cell-associated markers (NKG2D and its ligands Mic-A and Mic-B) using real-time quantitative polymerase chain reaction. T-plastin served as a positive genetic marker, and its expression correlated to blood tumor burden. More than 90% of samples had transcripts for CD28 and Mic-B, but less than 30% of samples expressed FoxP3, CTLA-4 and CD25. Expression of Mic-B by neoplastic cells could provide another mechanism to inhibit anti-tumor immune responses. FoxP3 expression correlated with a poor prognosis. Although the underlying mechanisms accounting for this correlation remain unclear, the expression of the Foxp3 and CTLA-4 regulatory elements indicates that a subset of leukemic cases displays a regulatory T-cell phenotype.

CXCL13 is highly produced by Sézary cells and enhances their migratory ability via a synergistic mechanism involving CCL19 and CCL21 chemokines

Chemokine and chemokine receptors expressed by normal and neoplastic lymphocytes play a key role in cell recruitment into skin and lymph nodes. The aim of this study was to get further insights into the role of chemokines in pathogenesis and progression of cutaneous T-cell lymphoma (CTCL) with particular regard to Sézary Syndrome (SS), a CTCL variant with blood involvement. Here, we show that functional CXCL13 homeostatic chemokine is strongly up-regulated in SS cells, well-detectable in skin lesions and lymph nodes, and measurable at high concentration in plasma of SS patients, at different levels during disease progression. Furthermore, we show that the addition of CXCL13 to CCL19 or to CCL21, the selective CCR7 agonists responsible for lymph node homing, strongly enhances the migration of CCR7+ SS cells. We also show that neutralization of the CCR7 receptor strongly impairs CCL19/21-induced chemotaxis of SS cells both in the absence or presence of CXCL13. Additional experiments performed to investigate the survival, adhesion, and metalloproteases secretion indicate that CXCL13 combined with CCL19 and CCL21 mainly affects the chemotaxis of SS cells. Our findings suggest that this newly described CXCL13 expression in SS represents a new pathogenetic mechanism of diagnostic significance.

The diagnosis of Sézary syndrome on peripheral blood by flow cytometry requires the use of multiple markers

BACKGROUND

Diagnosis of Sézary syndrome (SS)-defining blood involvement is hampered by the lack of Sézary cell-specific markers and nonspecific morphology of the tumour cells.

OBJECTIVES

To identify the most reliable and easy to use markers for the diagnosis of SS-defining blood involvement.

METHODS

We studied 17 patients with SS and 11 control patients. We used flow cytometry for the detection of T-cell antigens (CD3, CD4, CD7 and CD8), expression of the Sézary cell-associated marker CD158k and T-cell receptor (TCR)-Vbeta chain. Additionally, Sézary cells were identified by peripheral blood smear for lymphocytes with cerebriform nuclei.

RESULTS

It was not possible to diagnose blood involvement in all patients with SS by a single marker or method, although none of the markers was increased in the control population. Sézary cells were detected by blood smears in 13 of 17 (76%), by flow cytometry by their CD4+ CD7- CD3(dim) phenotype (> 1000 cells microL(-1)) in 13 of 17 (76%) and by expression of CD158k in 11 of 17 (65%) patients with SS. A specific T-cell clone was identified by identical TCR-Vbeta chain expression in 12 of 17 (71%) patients with SS. The identification of Sézary cells in individual patients varied for the different markers investigated.

CONCLUSIONS

The combination of identifying CD4+ CD7- CD3(dim) cells, TCR-Vbeta chain and CD158k expression allowed a definite identification of SS-defining blood involvement in every individual patient. All of these markers can be measured by flow cytometry which would avoid time-consuming analysis of blood smears. These markers would also be suitable to monitor tumour cell load during therapy.