Tumour cell generation of inducible regulatory T-cells in multiple myeloma is contact-dependent and antigen-presenting cell-independent

Novel expression of Neuropilin 1 on human tumor-infiltrating lymphocytes in colorectal cancer liver metastases

OBJECTIVES

Neuropilin 1 (NRP1) is a transmembrane protein with diverse roles in physiological and pathological settings. NRP1 expression has been reported on T cells in inflammatory microenvironments and in secondary lymphoid tissue. Tumor-infiltrating lymphocytes (TILs) play an important role in cancer prognosis. In this study, we investigated NRP1 expression on TILs and peripheral blood mononuclear cells (PBMCs) from colorectal cancer liver metastases (LI/CRC).

METHODS

TILs from LI/CRC and PBMCs from healthy donors and patients were analyzed for expression of NRP1, in addition to other Treg-related markers. PBMCs were co-cultured in vitro with tumor tissue and analyzed for NRP1 expression.

RESULTS

We report for the first time that NRP1 is highly expressed on CD3(+)CD4(+) TILs compared to PBMCs. NRP1 expression correlated closely with CD25 expression in TILs. NRP1 was expressed on both Helios(+) and Helios(-) FoxP3-expressing Tregs and on a FoxP3(-)Helios(-) T cell subset. It was also induced on PBMCs following in vitro co-culture with tumor tissue.

CONCLUSIONS

NRP1 is upregulated on TILs and can be induced on PBMCs by tumor tissue. Further studies are warranted to define the function of NRP1 on human TILs. As a therapeutic target, NRP1 may allow selective targeting of TIL subsets including suppressive Tregs.

GITR+ regulatory T cells in the treatment of autoimmune diseases

Autoimmune diseases decrease life expectancy and quality of life for millions of women and men. Although treatments can slow disease progression and improve quality of life, all currently available drugs have adverse effects and none of them are curative; therefore, requiring patients to take immunosuppressive drugs for the remainder of their lives. A curative therapy that is safe and effective is urgently needed. We believe that therapies promoting the in vivo expansion of regulatory T cells (Tregs) or injection of in vitro expanded autologous/heterologous Tregs (cellular therapy) can alter the natural history of autoimmune diseases. In this review, we present data from murine and human studies suggesting that 1) glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) plays a crucial role in thymic Treg (tTreg) differentiation and expansion; 2) GITR plays a crucial role in peripheral Treg (pTreg) expansion; 3) in patients with Sjögren syndrome and systemic lupus erythematosus, CD4(+)GITR(+) pTregs are expanded in patients with milder forms of the disease; and 4) GITR is superior to other cell surface markers to differentiate Tregs from other CD4(+) T cells. In this context, we consider two potential new approaches for treating autoimmune diseases consisting of the in vivo expansion of GITR(+) Tregs by GITR-triggering drugs and in vitro expansion of autologous or heterologous GITR(+) Tregs to be infused in patients. Advantages of such an approach, technical problems, and safety issues are discussed.

Cellular immunotherapy in multiple myeloma: lessons from preclinical models

The majority of multiple myeloma patients relapse with the current treatment strategies, raising the need for alternative therapeutic approaches. Cellular immunotherapy is a rapidly evolving field and currently being translated into clinical trials with encouraging results in several cancer types, including multiple myeloma. Murine multiple myeloma models are of critical importance for the development and refinement of cellular immunotherapy. In this review, we summarize the immune cell changes that occur in multiple myeloma patients and we discuss the cell-based immunotherapies that have been tested in multiple myeloma, with a focus on murine models.

CLL-cells induce IDOhi CD14+HLA-DRlo myeloid-derived suppressor cells that inhibit T-cell responses and promote TRegs

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population that shares certain characteristics including an aberrant myeloid phenotype and the ability to suppress T cells. MDSCs have been predominantly studied in malignant diseases and findings suggest involvement in tumor-associated immune suppression. Chronic lymphocytic leukemia (CLL) is the leukemia with the highest incidence among adults. Immune defects occur already at early disease stages and impact the clinical course. We assessed presence, frequency, association to other immune parameters, and functional properties of circulating CD14(+) cells lacking HLA-DR expression (HLA-DR(lo)) in patients with untreated CLL. These monocytic cells represent one of the best-defined human MDSC subsets. Frequency of CD14(+)HLA-DR(lo) cells was significantly increased in CLL patients. Furthermore, MDSCs suppressed in vitro T-cell activation and induced suppressive regulatory T cells (TRegs). The MDSC-mediated modulation of T cells could be attributed to their increased indoleamine 2,3-dioxygenase (IDO) activity. CLL cells induced IDO(hi) MDSCs from healthy donor monocytes suggesting bidirectional crosstalk between CLL-cells, MDSCs, and TRegs. Overall, we identified a MDSC population that expands in CLL. The exact mechanisms responsible for such accumulation remain to be elucidated and it will be of interest to test whether antagonizing suppressive functions of CLL MDSCs could represent a mean for enhancing immune responses.

Lenalidomide consolidation and maintenance therapy after autologous stem cell transplant for multiple myeloma induces persistent changes in T-cell homeostasis

Whether the efficacy of lenalidomide in the treatment of multiple myeloma (MM) is due to direct tumor toxicity only or to additional immunomodulatory effects is unclear. We studied the effect of lenalidomide treatment on T-cell immune reconstitution in patients with MM who had undergone autologous peripheral blood stem cell transplant (ASCT). Twenty-nine newly diagnosed patients with MM received induction therapy followed by high-dose melphalan and ASCT. After ASCT, 11 patients received lenalidomide consolidation therapy for 2 months followed by maintenance therapy until disease progression. The remaining 18 patients received no treatment. Serial analysis of thymic output, as given by numbers of T-cell receptor excision circles (sjTRECs), and T-cell phenotyping was performed until 18 months post-ASCT. Lenalidomide impaired long-term thymic T-cell reconstitution, decreased CD4 + and CD8 + CD45RA + CCR7 - effector-terminal T-cell absolute counts and increased CD4 + CD25 + CD127 - /low regulatory T-cells. Lenalidomide consolidation and long-term maintenance therapy, administered post-ASCT, may have a potentially negative impact on immune surveillance.

Myeloma skews regulatory T and pro-inflammatory T helper 17 cell balance in favor of a suppressive state

Abstract Discrepancies in the literature between regulatory T cell (Treg) and pro-inflammatory T helper 17 (Th17) numbers in multiple myeloma (MM) can be largely explained by technical differences in methodology and patient selection. In this study, Treg cells were defined as CD3(+)CD4(+)CD25(++)CD127(lo) cells. Patients with MM (n = 20) had a significant imbalance in Treg/Th17 ratio when compared with either aged-matched controls (n = 28) or other monoclonal gammopathies, and this was associated with a significantly worse survival. The percent Treg in bone marrow of patients with MM was higher than that in matched peripheral blood samples (p = 0.02), although FOXP3 expression within bone marrow T cells was lower (p = 0.02). We observed increased Treg function, both in vivo and in vitro, due at least partially to an increase in CTLA-4 expression by concurrent treatment with dexamethasone and immune modulatory compounds (iMiDs). We suggest that immunoregulatory balance is important during active chemotherapy and that conclusions related to the immunostimulatory effect of iMiDs based on in vitro testing must be considered with caution.

Contribution of regulatory T cells to immunosuppression and disease progression in multiple myeloma patients

Multiple myeloma (MM) patients exhibit consistent degrees of immune dysfunction. Regulatory T cells contribute to the establishment of an immunosuppressive status in MM patients, hence favoring disease progression.

Regulating the regulators in cancer-immunosuppression in multiple myeloma (MM)

An effective immune response requires a prompt but measured action against the pathological insult, to prevent over-zealous inflammatory-mediated tissue destruction. In cancer, defective or incompetent immune responses may paradoxically result in disease progression despite an immune attempt at elimination. Tumour-induced immunosuppression may not only result from soluble factors and altered antigenicity, but also from cellular-mediated tumour-induced immune evasion. Multiple myeloma (MM) is associated with both cellular and humoral immune deficiencies and increased T(Reg) cells. In vitro modelling has indicated that the tumour cells directly induce functional T(Reg) cells. In light of this recent evidence, it now seems that the most promising and synergistic approaches for cancer immunotherapy would involve specific anti-tumour immunity and simultaneous reduction of tumour-induced immune-regulation. This review sets out the basic understanding of the human immune response, its dysregulation in cancer and proposes how this knowledge may influence future treatment strategies to maximise the anti-tumour immune response.

Modulating T regulatory cells in cancer: how close are we?

Regulatory T cells (Tregs) are a specialized subset of CD4 T cells that have an indispensable role in maintaining immune homeostasis and tolerance. Although studies in mice and humans have clearly highlighted that the absence of these cells results in severe autoimmunity and inflammation, increased Treg numbers and/or function is not always beneficial. This is best exemplified in certain cancers where increased Tregs promote cancer progression by interfering with immune surveillance. Conversely, in other types of cancers that have an inflammatory component, Tregs can inhibit cancer progression by dampening inflammation. In this review article, we provide a historical perspective of the discovery of Tregs, followed by a summary of the existing literature on the role of Tregs in malignancy.

Epigenetics, autoimmunity and hematologic malignancies: a comprehensive review

The relationships between immunological dysfunction, loss of tolerance and hematologic malignancies have been a focus of attention in attempts to understand the appearance of a higher degree of autoimmune disease and lymphoma in children with congenital immunodeficiency. Although multiple hypotheses have been offered, it is clear that stochastic processes play an important role in the immunopathology of these issues. In particular, accumulating evidence is defining a role of epigenetic mechanisms as being critical in this continuous spectrum between autoimmunity and lymphoma. In this review, we focus attention predominantly on the relationships between T helper 17 (Th17) and T regulatory populations that alter local microenvironments and ultimately the expression or transcription factors involved in cell activation and differentiation. Abnormal expression in any of the molecules involved in Th17 and/or Treg development alter immune homeostasis and in genetically susceptible hosts may lead to the appearance of autoimmunity and/or lymphoma. These observations have clinical significance in explaining the discordance of autoimmunity in identical twins. They are also particularly important in the relationships between primary immune deficiency syndromes, immune dysregulation and an increased risk of lymphoma. Indeed, defining the factors that determine epigenetic alterations and their relationships to immune homeostasis will be a challenge greater or even equal to the human genome project.