The IL-15 cytokine system provides growth and survival signals in Hodgkin lymphoma and enhances the inflammatory phenotype of HRS cells

The role of interleukin-15 in the development and treatment of hematological malignancies

Cytokines are a vital component of the immune system that controls the activation and growth of blood cells. However, chronic overexpression of cytokines can trigger cellular events leading to malignant transformation. The cytokine interleukin-15 (IL-15) is of particular interest, which has been shown to contribute to the development and progression of various hematological malignancies. This review will provide an overview of the impact of the immunopathogenic function of IL-15 by studying its role in cell survival, proliferation, inflammation, and treatment resistance. We will also review therapeutic approaches for inhibiting IL-15 in blood cancers.

IL-2/IL-2R signaling and IL-2Rα-targeted therapy in anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) is a CD30-positive non-Hodgkin's T‑cell lymphoma. Despite the implementation of CD30 antibody-drug conjugate-targeted therapy into front-line treatment regimens, the prognosis of some subtypes of the disease remains unsatisfactory. In the relapsed/refractory setting, effective second-line treatment options are still lacking. However, it has been reported that blockade of direct downstream targets of activator protein‑1 (AP-1) transcription factors, which are highly dysregulated in ALCL, results in complete and sustained remission in late-stage relapsed/refractory anaplastic lymphoma kinase (ALK)-positive ALCL patients. Moreover, it has been identified that involvement of the BATF3/AP‑1 module promotes lymphomagenesis via oncogenic BATF3/IL-2/IL-2R signaling through hyperphosphorylation of ERK1/2, STAT1, and STAT5 in ALCL cells regardless of their ALK status. Therefore, targeting BATF3/IL-2/IL-2R signaling may represent a novel therapeutic alternative for ALCL patients.

The Tumor Suppressive mir-148a Is Epigenetically Inactivated in Classical Hodgkin Lymphoma

DNA methylation was shown previously to be a crucial mechanism responsible for transcriptional deregulation in the pathogenesis of classical Hodgkin lymphoma (cHL). To identify epigenetically inactivated miRNAs in cHL, we have analyzed the set of miRNAs downregulated in cHL cell lines using bisulfite pyrosequencing. We focused on miRNAs with promoter regions located within or <1000 bp from a CpG island. Most promising candidate miRNAs were further studied in primary Hodgkin and Reed-Sternberg (HRS) cells obtained by laser capture microdissection. Last, to evaluate the function of identified miRNAs, we performed a luciferase reporter assay to confirm miRNA: mRNA interactions and therefore established cHL cell lines with stable overexpression of selected miRNAs for proliferation tests. We found a significant reverse correlation between DNA methylation and expression levels of mir-339-3p, mir-148a-3p, mir-148a-5p and mir-193a-5 demonstrating epigenetic regulation of these miRNAs in cHL cell lines. Moreover, we demonstrated direct interaction between miR-148a-3p and IL15 and HOMER1 transcripts as well as between mir-148a-5p and SUB1 and SERPINH1 transcripts. Furthermore, mir-148a overexpression resulted in reduced cell proliferation in the KM-H2 cell line. In summary, we report that mir-148a is a novel tumor suppressor inactivated in cHL and that epigenetic silencing of miRNAs is a common phenomenon in cHL.

Formation of the Immunosuppressive Microenvironment of Classic Hodgkin Lymphoma and Therapeutic Approaches to Counter It

Classic Hodgkin lymphoma (cHL) is characterized by a few tumor cells surrounded by a protective, immunosuppressive tumor microenvironment composed of normal cells that are an active part of the disease. Hodgkin and Reed-Sternberg (HRS) cells evade the immune system through a variety of different mechanisms. They evade antitumor effector T cells and natural killer cells and promote T cell exhaustion. Using cytokines and extracellular vesicles, they recruit normal cells, induce their proliferation and "educate" (i.e. reprogram) them to become immunosuppressive and protumorigenic. Therefore, alternative treatment strategies are being developed to target not only tumor cells but also the tumor microenvironment. Here we summarize current knowledge on the ability of HRS cells to build their microenvironment and to educate normal cells to become immunosuppressive. We also describe therapeutic strategies to counteract formation of the tumor microenvironment and related processes leading to T cell exhaustion and repolarization of immunosuppressive tumor-associated macrophages.

The role of cytokines in the regulation of NK cells in the tumor environment

Natural killer (NK) cells are innate lymphoid cells that are important effectors in the first line of defense toward transformed cells. This is mediated both by direct cytotoxic mechanisms and by production of immunoregulatory cytokines. Recent evidence has shown that NK cells also display memory, similar to the cells of the adaptive immune system. Cytokines are pivotal for the maturation, activation and survival of NK cells. Interleukins (IL)-2, IL-12, IL-15, IL-18, IL-21 and type I interferons positively regulate NK cell function, either independently or in cooperation, whereas other cytokines, such as IL-23 and IL-27, may enhance or suppress NK cell function depending on the context. In the tumor microenvironment, TGFβ, IL-10 and IL-6 suppress NK cell activity not only directly, but also indirectly, by affecting immunosuppressive cells and by antagonizing the effect of stimulatory cytokines, thereby dampening the antitumor response of NK cells and promoting subsequent tumor evasion and progression. Increased understanding of the NK cell response to cytokines has provided a better understanding of their impaired function in tumors which may aid in the development of novel immunotherapeutic strategies to enhance NK cell responses in cancer patients.

Effect of Roasting Levels and Drying Process of Coffea canephora on the Quality of Bioactive Compounds and Cytotoxicity

Coffee is a popular drink consumed all over the world. Besides its long-recognized stimulant effect, it has important nutritional and health effects. However, the type of bean processing modifies the composition of brewed coffee and possibly its bioactivity. In this study, extracts obtained from green and roasted beans of Coffea canephora (Coffea canephora var. robusta) were submitted to spray- or freeze-drying and were tested for antiproliferative activity, using MTT assay, and their influence on the cell cycle and apoptosis by flow cytometry analysis. Moreover, colors and nutrient contents were measured to identify the changes due to the roasting process. The results obtained showed that extracts from green and light roasted beans exhibited strong bioactive capacity. Coffee extracts promoted a decrease in cell viability, modulated cell cycle and induced apoptosis in human prostate carcinoma cell line (DU-145). The level of roasting reduced this property, but the type of drying did not in all cases.

Mechanistic Insights into CpG DNA and IL-15 Synergy in Promoting B Cell Chronic Lymphocytic Leukemia Clonal Expansion

Malignant cell growth within patients with B cell chronic lymphocytic leukemia (B-CLL) is largely restricted to lymphoid tissues, particularly lymph nodes. The recent in vitro finding that TLR-9 ligand (oligodeoxynucleotide [ODN]) and IL-15 exhibit strong synergy in promoting B-CLL growth may be particularly relevant to growth in these sites. This study shows IL-15-producing cells are prevalent within B-CLL-infiltrated lymph nodes and, using purified B-CLL cells from blood, investigates the mechanism for ODN and IL-15 synergy in driving B-CLL growth. ODN boosts baseline levels of phospho-RelA(S529) in B-CLL and promotes NF-κB-driven increases in IL15RA and IL2RB mRNA, followed by elevated IL-15Rα and IL-2/IL-15Rβ (CD122) protein. IL-15→CD122 signaling during a critical interval, 20 to 36-48 h following initial ODN exposure, is required for optimal induction of the cycling process. Furthermore, experiments with neutralizing anti-IL-15 and anti-CD122 mAbs indicate that clonal expansion requires continued IL-15/CD122 signaling during cycling. The latter is consistent with evidence of heightened IL2RB mRNA in the fraction of recently proliferated B-CLL cells within patient peripheral blood. Compromised ODN+IL-15 growth with limited cell density is consistent with a role for upregulated IL-15Rα in facilitating homotypic trans IL-15 signaling, although there may be other explanations. Together, the findings show that ODN and IL-15 elicit temporally distinct signals that function in a coordinated manner to drive B-CLL clonal expansion.

Acquired Natural Killer Cell Dysfunction in the Tumor Microenvironment of Classic Hodgkin Lymphoma

An understanding of interactions within the tumor microenvironment (TME) of classic Hodgkin lymphoma (cHL) has helped pave the way to novel immunotherapies that have enabled dormant and tumor-tolerant immune cells to be reactivated. The immunosuppressive nature of the TME in cHL specifically inhibits the proliferation and activity of natural killer (NK) cells, which contributes to tumor immune-escape mechanisms. This deficiency of NK cells begins at the tumor site and progresses systemically in patients with advanced disease or adverse prognostic factors. Several facets of cHL account for this effect on NK cells. Locally, malignant Reed-Sternberg cells and cells from the TME express ligands for inhibitory receptors on NK cells, including HLA-E, HLA-G, and programmed death-ligand 1. The secretion of chemokines and cytokines, including soluble IL-2 receptor (sCD25), Transforming Growth Factor-β, IL-10, CXCL9, and CXCL10, mediates the systemic immunosuppression. This review also discusses the potential reversibility of quantitative and functional NK cell deficiencies in cHL that are likely to lead to novel treatments.

Complex Immune Evasion Strategies in Classical Hodgkin Lymphoma

The cellular microenvironment in classical Hodgkin lymphoma (cHL) is dominated by a mixed infiltrate of inflammatory cells with typically only about 1% Hodgkin and Reed/Sternberg (HRS) tumor cells. T cells are usually the largest population of cells in the cHL microenvironment, encompassing T helper (Th) cells, regulatory T cells (Tregs), and cytotoxic T cells. Th cells and Tregs presumably provide essential survival signals for HRS cells. Tregs are also involved in rescuing HRS cells from antitumor immune responses. An understanding of the immune evasion strategies of HRS cells is not only relevant for a characterization of the pathophysiology of cHL but is also clinically relevant, given the current treatment approaches targeting checkpoint inhibitors. Here, we characterized the cHL-specific CD4⁺ T-cell infiltrate regarding its role in immune evasion. Global gene expression analysis of CD4⁺ Th cells and Tregs isolated from cHL lymph nodes and reactive tonsils revealed that Treg signatures were enriched in CD4⁺ Th cells of cHL. Hence, HRS cells may induce Treg differentiation in Th cells, a conclusion supported by in vitro studies with Th cells and cHL cell lines. We also found evidence for immune-suppressive purinergic signaling and a role of the inhibitory receptor-ligand pairs B- and T-cell lymphocyte attenuator-herpesvirus entry mediator and CD200R-CD200 in promoting immune evasion. Taken together, this study highlights the relevance of Treg induction and reveals new immune checkpoint-driven immune evasion strategies in cHL. Cancer Immunol Res; 5(12); 1122-32. ©2017 AACR.

Comparison of serum cytokine levels between dogs with multicentric lymphoma and healthy dogs

In humans, multiple cytokines have been linked to the development of lymphoma, and are relevant biomarkers for response to chemotherapy and prognosis. In contrast, only a few circulating cytokines have been studied in dogs with lymphoma. We prospectively enrolled thirty-one dogs newly diagnosed with multicentric lymphoma. Immunophenotype was determined by flow cytometry in all dogs, separating them into 2 subgroups: B cell lymphoma (n=21) and T cell lymphoma (n=10). Nineteen healthy dogs were enrolled in the control group. Circulating cytokine concentrations were measured using a commercial canine multiplex magnetic bead-based assay which included Interleukin-2 (IL-2), IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF), Tumor Necrosis Factor-α (TNF-α), Interferon γ (IFN-γ), IFN-γ induced Protein-10 (IP-10), Keratinocyte Chemoattractant-like (KC-like), and Monocyte Chemoattractant Protein-1 (MCP-1). The serum levels of each cytokine were first compared between the lymphoma and control groups, and then between the B cell lymphoma, T cell lymphoma, and control groups. There was no significant difference between the lymphoma and healthy control groups regarding sex, age and weight. MCP-1, IL-6, and IL-10 were significantly higher in dogs with lymphoma compared to healthy dogs (p<0.01, p=0.01 and p=0.03, respectively). MCP-1 and IL-10 were significantly higher in the B cell lymphoma group than in the healthy group (p=0.01, p=0.01, respectively). MCP-1 and IL-6 levels were significantly higher in the T cell lymphoma group than in the healthy group (p=0.02, p<0.01, respectively). IL-6 was significantly higher in the T cell lymphoma group than in the B cell lymphoma group (p=0.03). Significant differences among the groups were found for IL-15 and KC-like, but they were affected by age and/or sex. There were no significant differences in serum IL-2, IL-7, IL-8, IL-18, GM-CSF, TNF-α, IFN-γ, and IP-10 between any of the groups. Significant differences in red blood cell, white blood cell, neutrophil, lymphocyte and monocyte counts were also found between the different groups of dogs. Our data showed different serum cytokine and peripheral blood cell profiles between dogs with lymphoma and healthy dogs, and between dogs with B cell and T cell lymphoma. Further study is necessary to investigate the role of these cytokines in lymphoma pathogenesis, response to treatment, and prognosis, and the influence of age, sex and blood cell counts on their expression.

CD137 signaling in Hodgkin and Reed-Sternberg cell lines induces IL-13 secretion, immune deviation and enhanced growth

CD137 and its ligand, CD137L, are expressed on activated T cells and antigen-presenting cells (APC), respectively, and are powerful inducers of cellular, type 1 immune responses. CD137 is ectopically expressed by Hodgkin and Reed-Sternberg (HRS) cells, the malignant cells in Hodgkin lymphoma (HL). Here we report that CD137 transmits signals into HRS cells, which induce the secretion of IL-13. IL-13 in conditioned supernatants of HRS cell lines inhibits the secretion of IFNγ by peripheral blood mononuclear cells (PBMC). Since IFNγ is essential for the development of a type 1 immune response, CD137-induced IL-13 secretion facilitates escape from immune surveillance. Further, CD137-induced IL-13 enhances the growth of HRS cell lines. CD137, IL-13 double-positive cells could be detected in the majority (58%) of HL patient samples, providing clinical evidence for a role of IL-13 induction by CD137 during HL pathogenesis. This study validates CD137 as a candidate target for immunotherapy of HL.

New insights of common gamma chain in hematological malignancies

The common gamma chain (γc) receptor family of cytokines including interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21 has the common feature of sharing γc signaling subunit of their receptors. The γc cytokines have unique biological effects that regulate differentiation, survival and activation of multiple lymphocyte lineages and control proliferation of malignant cell by influencing tumor environment. It has been also described that different types of lymphoid leukemia and lymphoma exhibit expression of divergent γc cytokines and their receptors, as they may promote malignant transformation of lymphoid cells or on the contrary lead to tumor regression by inducing cell-cycle arrest. Therefore, cytokine-based or cytokine-directed blockade in cancer immunotherapy has currently revolutionized the development of cancer treatment. In this review, we will discuss about the role of γc cytokines and their signaling pathways in hematological malignancies and also propose a novel alternative approach that regulates γc cytokine responsiveness by γc in hematological malignancies.