Angioimmunoblastic T-cell lymphoma mice model

Junction of the redox dynamic, orchestra of signaling, and altered metabolism in regulation of T- cell lymphoma

T-cell lymphoma is a hematologic neoplasm derived from the lymphoid lineage. It belongs to a diverse group of malignant disorders, mostly affecting the young population worldwide, that vary with respect to molecular features as well as genetic and clinical complexities. Cancer cells rewire the cellular metabolism, persuading it to meet new demands of growth and proliferation. Furthermore, the metabolic alterations and heterogeneity are aberrantly driven in cancer by a combination of genetic and non-genetic factors, including the tumor microenvironment. New insight into cancer metabolism highlights the importance of nutrient supply to tumor development and therapeutic responses. Importantly, oxidative stress due to an imbalance in the redox status of reactive species via exogenous and/or endogenous factors is closely related to multiple aspects of cancer. This alters the signaling pathways governed through the multiple intracellular signal transduction and transcription factors, leading to tumor progression. These oncogenic signaling molecules are regulated through different redox sensors, including nuclear factor-erythroid 2 related factor 2 (Nrf2), phase-II antioxidant enzyme, and NQO1 (NADPH quinone oxidoreductase (1). The existing understanding of the molecular mechanisms of T-cell lymphoma regulation through the cross-talk of redox sensors under the influence of metabolic vulnerability is not well explored. This review highlights the role of the redox dynamics, orchestra of signaling, and genetic regulation involved in T-cell lymphoma progression in addition to the challenges to their etiology, treatment, and clinical response in light of recent updates.

The Early Diagnostic Dilemma in Angioimmunoblastic T Cell Lymphoma with Excessive Plasma Cells Proliferation

Background

Angioimmunoblastic T cell lymphoma (AITL) is an aggressive Epstein–Barr virus-associated T cell lymphoma. Clinical syndromes of AITL are not confined to fever and lymphadenopathy, and patients may initially present with polyclonal plasma cell proliferation, which may obscure the underlying disease of AITL, delaying diagnosis. Case Presentation. Here, we report two AITL patients with excessive plasma cell proliferation in the bone marrow, peripheral blood, and ascites even mimicking plasma cell leukemia. Both of them had poor endings.

Conclusions

Our report emphasizes the complexity of the clinical manifestations of AITL, which aims to increase the alertness of physicians and improve the rate of early diagnosis. Integrated diagnostic approaches such as histopathology, flow cytometry, cytogenetics, and molecular biology are essential for accurate diagnosis and precise therapy.

Progression of AITL-like tumors in mice is driven by Tfh signature proteins and T-B cross talk

Angioimmunoblastic T-cell lymphoma (AITL) is an aggressive peripheral T-cell lymphoma driven by a pool of neoplastic cells originating from T follicular helper (Tfh) cells and concomitant expansion of B cells. Conventional chemotherapies for AITL have shown limited efficacy, and as such, there is a need for improved therapeutic options. Because AITL originates from Tfh cells, we hypothesized that AITL tumors continue to rely on essential Tfh components and intimate T-cell-B-cell (T-B) interactions. Using a spontaneous AITL mouse model (Roquinsan/+ mice), we found that acute loss of Bcl6 activity in growing tumors drastically reduced tumor size, demonstrating that AITL-like tumors critically depend on the Tfh lineage-defining transcription factor Bcl6. Because Bcl6 can upregulate expression of signaling lymphocytic activation molecule-associated protein (SAP), which is known to promote T-B conjugation, we next targeted the SAP-encoding Sh2d1a gene. We observed that Sh2d1a deletion from CD4+ T cells in fully developed tumors also led to tumor regression. Further, we provide evidence that tumor progression depends on T-B cross talk facilitated by SAP and high-affinity LFA-1. In our study, AITL-like tumors relied heavily on molecular pathways that support Tfh cell identity and T-B collaboration, revealing potential therapeutic targets for AITL.

Role of Microenvironment in Non-Hodgkin Lymphoma: Understanding the Composition and Biology

Lymphoma microenvironment is a dynamic and well-orchestrated network of various immune and stromal cells that is indispensable for tumor cell survival, growth, migration, immune escape, and drug resistance. Recent progress has enhanced our knowledge of the pivotal role of microenvironment in lymphomagenesis. Understanding the characteristics, functions, and contributions of various components of the tumor niche, along with its bidirectional interactions with tumor cells, is paramount. It offers the potential to identify new therapeutic targets with the ability to restore antitumor immune surveillance and eliminate the protumoral factors contributed by the tumor niche.

New preclinical models for angioimmunoblastic T-cell lymphoma: filling the GAP

Mouse models are essential to study and comprehend normal and malignant hematopoiesis. The ideal preclinical model should mimic closely the human malignancy. This means that these mice should recapitulate the clinical behavior of the human diseases such as cancer and therapeutic responses with high reproducibility. In addition, the genetic mutational status, the cell phenotype, the microenvironment of the tumor and the time until tumor development occurs, should be mimicked in a preclinical model. This has been particularly challenging for human angioimmunoblastic lymphoma (AITL), one of the most prominent forms of peripheral T-cell lymphomas. A complex network of interactions between AITL tumor cells and the various cells of the tumor microenvironment has impeded the study of AITL pathogenesis in vitro. Very recently, new mouse models that recapitulate faithfully the major features of human AITL disease have been developed. Here, we provide a summary of the pathology, the transcriptional profile and genetic and immune-phenotypic features of human AITL. In addition, we give an overview of preclinical models that recapitulate more or less faithfully human AITL characteristics and pathology. These recently engineered mouse models were essential in the evaluation of novel therapeutic agents for possible treatment of AITL, a malignancy in urgent need of new treatment options.

Lymphomas and Their Microenvironment: A Multifaceted Relationship

It has become evident that the microenvironment - lymphocytes, macrophages, fibroblasts as well as the extracellular matrix, cytokines, chemokines, and a plethora of other cells, structures and substances residing in the vicinity of tumor cells - plays an important part in the maintenance of cancer growth and survival. This is also relevant in lymphomas. In this review, we give an outline on the importance of the microenvironment for tumors in general and lymphomas in particular, by highlighting certain basic principles of tumor-microenvironment interaction. The relationship of lymphomas and their microenvironment is multifaceted: lymphoma cells need growth factors and cytokines derived from microenvironmental cells for their sustenance and growth. On the contrary, many lymphomas silence or at least deregulate the immune system to escape recognition and subsequent elimination by immune cells, while giving advantage to suppressive microenvironmental compounds such as M2 polarized macrophages, regulatory T-cells, mast cells, and immunosuppressive fibroblasts. We also give a detailed insight across different lymphoma types to show the variety of tumor-microenvironment interactions. Due to its tremendous importance, the microenvironment has also become a new target for oncologic therapy. The most important finding concerning lymphomas with a focus on immunomodulatory substances is also, therefore, highlighted.

Tumor Microenvironment in T-Cell Lymphomas

T-cell lymphomas (TCL) are uncommon non-Hodgkin lymphomas that often have an aggressive clinical course. Patients typically have limited treatment options upon relapse and a dismal prognosis after progression despite newly approved therapies. New therapeutic approaches for these orphan diseases are very much needed and a greater understanding of the role of nonmalignant immune cells in the tumor microenvironment may allow for an improved antitumor immune response. The tumor microenvironment is a key component in tumor evasion and typically results in an ineffective T-cell response to the tumor cells despite a significant inflammatory response. A better understanding of the tumor microenvironment therefore, in an effort to overcome the barriers to an effective immune response, would help in developing novel therapeutic approaches to treat and improve outcomes of these diseases. Immune checkpoint blockade to reinvigorate suppressed T-cell, or modulation of the CD47-SIRPalpha axis to promote macrophage phagocytosis, would be such targets. However, whether modulating the immune response using each pathway alone or whether a combination approach is necessary has yet to be determined.

Molecular Pathogenesis of Peripheral T Cell Lymphoma

Understanding the molecular pathogenesis of peripheral T cell lymphomas (PTCLs) has lagged behind that of B cell lymphomas due to disease rarity. However, novel approaches are gradually clarifying these mechanisms, and gene profiling has identified specific signaling pathways governing PTCL cell survival and growth. For example, genetic alterations have been discovered, including signal transducer and activator of transcription (STAT)3 and STAT5b mutations in several PTCLs, disease-specific ras homolog family member A (RHOA) mutations in angioimmunoblastic T cell lymphoma (AITL), and recurrent translocations at the dual specificity phosphatase 22 (DUSP22) locus in anaplastic lymphoma receptor tyrosine kinase (ALK)-negative anaplastic large cell lymphomas (ALCLs). Intriguingly, some PTCL-relevant mutations are seen in apparently normal blood cells as well as tumor cells, while others are confined to tumor cells. These data have dramatically changed our understanding of PTCL origins: once considered to originate from mature T lymphocytes, some PTCLs are now believed to emerge from immature hematopoietic progenitor cells.

The microenvironment in T-cell lymphomas: emerging themes

Peripheral T-cell lymphomas (PTCLs) are heterogeneous and uncommon malignancies characterized by an aggressive clinical course and a mostly poor outcome with current treatment strategies. Despite novel insights into their pathobiology provided by recent genome-wide molecular studies, several entities remain poorly characterized. In addition to the neoplastic cell population, PTCLs have a microenvironment component, composed of non-tumor cells and stroma, which is quantitatively and qualitatively variable, and which may have an effect on their pathological and clinical features. The best example is provided by angioimmunoblastic T-cell lymphoma (AITL), a designation reflecting the typical vascularization and reactive immunoblastic content of the tumor tissues. In this disease, a complex network of interactions between the lymphoma cells and the microenvironment exists, presumably mediated by the neoplastic T cells with follicular helper T-cell properties. A better understanding of the crosstalk between neoplastic T or NK cells and their microenvironment may have important implications for guiding the development of novel therapies.

Oncogenic isocitrate dehydrogenase mutations: mechanisms, models, and clinical opportunities

Heterozygous mutations in catalytic arginine residues of isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) are common in glioma, acute myeloid leukemia, chondrosarcoma, cholangiocarcinoma, and angioimmunoblastic T-cell lymphoma. The mutant enzymes acquire a neomorphic activity that converts α-ketoglutarate (α-KG) to D-2-hydroxyglutarate (D2HG), a rare metabolite. In cells and tissues expressing mutant IDH, D2HG concentrations are highly elevated. D2HG may act as an "oncometabolite" by inhibiting a class of α-KG-dependent enzymes involved in epigenetic regulation, collagen synthesis, and cell signaling. Knock-in mouse models of IDH1 mutations have shed light on these mechanisms and will provide valuable animal models for further investigation.

Autologous Tax-specific CTL therapy in a primary adult T cell leukemia/lymphoma cell-bearing NOD/Shi-scid, IL-2Rγnull mouse model

We expanded human T-lymphotropic virus type 1 Tax-specific CTL in vitro from PBMC of three individual adult T cell leukemia/lymphoma (ATL) patients and assessed their therapeutic potential in an in vivo model using NOG mice bearing primary ATL cells from the respective three patients (ATL/NOG). In these mice established with cells from a chronic-type patient, treatment by i.p. injection of autologous Tax-CTL resulted in greater infiltration of CD8-positive T cells into each ATL lesion. This was associated with a significant decrease of ATL cell infiltration into blood, spleen, and liver. Tax-CTL treatment also significantly decreased human soluble IL-2R concentrations in the sera. In another group of ATL/NOG mice, Tax-CTL treatment led to a significant prolongation of survival time. These findings show that Tax-CTL can infiltrate the tumor site, recognize, and kill autologous ATL cells in mice in vivo. In ATL/NOG mice with cells from an acute-type patient, whose postchemotherapeutic remission continued for >18 mo, antitumor efficacy of adoptive Tax-CTL therapy was also observed. However, in ATL/NOG mice from a different acute-type patient, whose ATL relapsed after 6 mo of remission, no efficacy was observed. Thus, although the therapeutic effects were different for different ATL patients, to the best of our knowledge, this is the first report that adoptive therapy with Ag-specific CTL expanded from a cancer patient confers antitumor effects, leading to significant survival benefit for autologous primary cancer cell-bearing mice in vivo. The present study contributes to research on adoptive CTL therapy, which should be applicable to several types of cancer.