Steven C. Ziesmer

IL-12 upregulates TIM-3 expression and induces T cell exhaustion in patients with follicular B cell non-Hodgkin lymphoma

The cytokine IL-12 induces IFN-γ production by T and NK cells. In preclinical models, it contributes to antitumor immunity. However, in clinical testing, it has shown limited benefit in patients with any one of a variety of malignancies. Moreover, in a clinical trial testing a combination of IL-12 and rituximab in patients with follicular B cell non-Hodgkin lymphoma (FL), those treated with IL-12 showed a lower response rate, suggesting that IL-12 actually plays a detrimental role. Here, we investigated whether the failure of IL-12 treatment for FL was due to T cell exhaustion, a condition characterized by reduced T cell differentiation, proliferation, and function, which has been observed in chronic viral infection. We found that extended exposure to IL-12 induced T cell exhaustion and contributed to the poor prognosis in FL patients. Long-term exposure of freshly isolated human CD4+ T cells to IL-12 in vitro caused T cell dysfunction and induced expression of TIM-3, a T cell immunoglobulin and mucin domain protein with a known role in T cell exhaustion, via an IFN-γ-independent mechanism. TIM-3 was required for the negative effect of IL-12 on T cell function. Importantly, TIM-3 also was highly expressed on intratumoral T cells that displayed marked functional impairment. Our findings identify IL-12- and TIM-3-mediated exhaustion of T cells as a mechanism for poor clinical outcome when IL-12 is administered to FL patients.

Temsirolimus and rituximab in patients with relapsed or refractory mantle cell lymphoma: a phase 2 study

BACKGROUND Temsirolimus is a mammalian target of rapamycin (mTOR) inhibitor with single-agent antitumour activity in patients with mantle cell lymphoma. We therefore tested its efficacy and toxicity in combination with rituximab (an antiCD20 antibody) in patients with relapsed or refractory mantle cell lymphoma. METHODS In a phase 2 study, patients (aged ≥18 years) at 35 centres in the USA were given temsirolimus 25 mg/week, and rituximab 375 mg/m(2) per week for 4 weeks during the first cycle and thereafter a single dose of rituximab every other 28-day cycle. Both drugs were administered intravenously. Responding patients after six cycles could continue treatment for a total of 12 cycles, and were then observed without additional maintenance treatment. The primary endpoint was the proportion of patients with either rituximab-sensitive or rituximab-refractory disease who had at least a partial response. The analyses were done on all patients who were treated. The study was registered with ClinicalTrials.gov, number NCT00109967. FINDINGS 71 patients with mantle cell lymphoma were enrolled and 69 were assessable and were included in the final analysis. The overall response rate (ORR) was 59% (41 of 69 patients)-13 (19%) patients had complete responses and 28 (41%) had partial responses. The ORR was 63% (30 of 48; 95% CI 47-76) for rituximab-sensitive patients, and 52% (11 of 21; 30-74) for rituximab-refractory patients. The most common treatment-related grade 3 or 4 adverse events in rituximab-sensitive and rituximab-refractory patients were thrombocytopenia (eight [17%] and eight [38%], respectively), neutropenia (ten [21%] and five [24%], respectively), fatigue (eight [17%] and two [10%], respectively), leucopenia (six [13%] and three [14%], respectively), pneumonia (five [10%] and two [10%], respectively), lymphopenia (five [10%] and two [10%], respectively), pneumonitis (four [8%] and none, respectively), oedema (four [8%] and none, respectively), dyspnoea (three [6%] and two [10%], respectively), and hypertriglyceridaemia (three [6%] and two [10%], respectively). INTERPRETATION mTOR inhibitors in combination with rituximab could have a role in the treatment of patients with relapsed and refractory mantle cell lymphoma. FUNDING National Institutes of Health and the Predolin Foundation.

Attenuation of CD8(+) T-cell function by CD4(+)CD25(+) regulatory T cells in B-cell non-Hodgkin's lymphoma.

The underlying mechanisms by which tumor cells are resistant to CTL-mediated apoptosis are not clear. Using a human model of B-cell non-Hodgkins lymphoma (B-cell NHL), we show that intratumoral T(reg) cells inhibit the proliferation and granule production of activated autologous infiltrating CD8(+) T cells. Our results also show that degranulation and subsequent cytotoxic activity of infiltrating CD8(+) T cells exposed to lymphoma B cells is completely attenuated by the presence of intratumoral T(reg) cells. Furthermore, we show that increased numbers of intratumoral T(reg) cells correlates with the number of CD8(+) T cells in biopsy specimens from patients with B-cell NHL, supporting the in vitro findings that intratumoral T(reg) cells inhibit proliferation of infiltrating CD8(+) T cells. Taken together, these data indicate that human lymphoma B cells are sensitive to autologous CTL-mediated cell death but are protected by the inhibitory function of intratumoral T(reg) cells.

The expression of Fas Ligand by macrophages and its upregulation by human immunodeficiency virus infection.

Fas/Fas Ligand (FasL) interactions play a significant role in peripheral T lymphocyte homeostasis and in certain pathological states characterized by T cell depletion. In this study, we demonstrate that antigen-presenting cells such as monocyte-derived human macrophages (MDM) but not monocyte-derived dendritic cells express basal levels of FasL. HIV infection of MDM increases FasL protein expression independent of posttranslational mechanisms, thus highlighting the virus-induced transcriptional upregulation of FasL. The in vitro relevance of these observations is confirmed in human lymphoid tissue. FasL protein expression is constitutive and restricted to tissue macrophages and not dendritic cells. Moreover, a significant increase in macrophage-associated FasL is observed in lymphoid tissue from HIV (+) individuals (P < 0.001), which is further supported by increased levels of FasL mRNA using in situ hybridization. The degree of FasL protein expression in vivo correlates with the degree of tissue apoptosis (r = 0.761, P < 0. 001), which is significantly increased in tissue from HIV-infected patients (P < 0.001). These results identify human tissue macrophages as a relevant source for FasL expression in vitro and in vivo and highlight the potential role of FasL expression in the immunopathogenesis of HIV infection.

Malignant B Cells Skew the Balance of Regulatory T Cells and TH17 Cells in B-Cell Non-Hodgkin's Lymphoma

Using biopsy specimens from patients with B-cell non-Hodgkins lymphoma, we observed a significantly low frequency of T(H)17 cells, including several samples with no detectable amount of interleukin (IL)-17-producing cells present in the tumor microenvironment. We found that, in the absence of lymphoma B cells, treatment with IL-1beta/IL-6 or lipopolysaccharide (LPS) enhanced IL-17 expression in CD4(+) T cells and this enhancement was attenuated when CD4(+) T cells were cocultured with lymphoma B cells. Blockade of CD27-CD70 or CD28-CD80/86 interactions by anti-CD70 or anti-CD80/86 antibodies restored LPS-mediated induction of IL-17 expression in CD4(+) T cells cocultured with lymphoma B cells. Because a subset of lymphoma B cells express IL-2 and given that IL-2 signaling is critically important in the development of regulatory T (T(reg)) cells, we tested the role of IL-2 signaling in T(H)17 cell development. We found that treatment with anti-IL-2 antibody to interrupt IL-2 signaling significantly inhibited Foxp3 expression in CD4(+) T cells. In contrast, interruption of IL-2 signaling up-regulated IL-17 expression in CD4(+) T cells and restored lymphoma-mediated down-regulation of IL-17-producing cells. Furthermore, the reversal of T(reg) cell activity by LPS or CpG-A resulted in an enhancement of IL-17-producing cells. Taken together, our study indicated that lymphoma B cells play an important role in skewing the balance between T(reg) and T(H)17 cells resulting in the establishment of a profoundly inhibitory tumor microenvironment.

Monocytes promote tumor cell survival in T-cell lymphoproliferative disorders and are impaired in their ability to differentiate into mature dendritic cells

A variety of nonmalignant cells present in the tumor microenvironment promotes tumorigenesis by stimulating tumor cell growth and metastasis or suppressing host immunity. The role of such stromal cells in T-cell lymphoproliferative disorders is incompletely understood. Monocyte-derived cells (MDCs), including professional antigen-presenting cells such as dendritic cells (DCs), play a central role in T-cell biology. Here, we provide evidence that monocytes promote the survival of malignant T cells and demonstrate that MDCs are abundant within the tumor microenvironment of T cell-derived lymphomas. Malignant T cells were observed to remain viable during in vitro culture with autologous monocytes, but cell death was significantly increased after monocyte depletion. Furthermore, monocytes prevent the induction of cell death in T-cell lymphoma lines in response to either serum starvation or doxorubicin, and promote the engraftment of these cells in nonobese diabetic/severe combined immunodeficient mice. Monocytes are actively recruited to the tumor microenvironment by CCL5 (RANTES), where their differentiation into mature DCs is impaired by tumor-derived interleukin-10. Collectively, the data presented demonstrate a previously undescribed role for monocytes in T-cell lymphoproliferative disorders.

Elevated Serum B-Lymphocyte Stimulator Levels in Patients With Familial Lymphoproliferative Disorders

PURPOSE Serum B-lymphocyte stimulator (BLyS) levels have been found to be elevated in a number of immune disease models. Therefore, we sought to establish whether BLyS levels were elevated in patients with B-cell lymphoproliferative disorders and to determine whether elevated BLyS levels correlated with clinical characteristics of the disease. PATIENTS AND METHODS Specimens were collected from the peripheral blood of individuals diagnosed with B-cell chronic lymphocytic leukemia (B-CLL; n = 70) or from age- and sex-matched patients seen at the same institution (n = 41). Serum BLyS levels were determined by enzyme-linked immunosorbent assay, and sequencing of the BLyS promoter was performed by conventional methods and confirmed by restriction fragment length polymorphism analysis. RESULTS We found that elevated BLyS levels were more common in patients with familial B-CLL than individuals with sporadic B-CLL or normal controls. Because of this association, we sequenced the BLyS promoter in patients with B-CLL and normal controls and identified a polymorphic site, -871 C/T. We found that the wild-type sequence was significantly underrepresented in patients with familial B-CLL (4%) compared with patients with sporadic B-CLL (30%; P = .01) or controls (24%; P = .04). Furthermore, using a luciferase reporter under control of the BLyS promoter containing either a C or a T at position -871, we found that the reporter construct containing a T at -871 had a 2.6-fold increase in activity (P = .004). CONCLUSION Our data suggest serum BLyS levels are elevated in patients with familial B-CLL and that elevated BLyS levels correlate with the presence of a T at -871 in the BLyS promoter.

Soluble IL-2Rα facilitates IL-2–mediated immune responses and predicts reduced survival in follicular B-cell non-Hodgkin lymphoma

Elevated serum levels of the soluble form of IL-2 receptor α (sIL-2Rα) have been correlated with a poor prognosis in a variety of different types of cancers. However, its biologic relevance remains unclear and controversial. In patients with follicular B-cell non-Hodgkin lymphoma (FL), we observed that serum sIL-2Rα levels were elevated compared with controls and that elevated sIL-2Rα levels before treatment were associated with a poor outcome. To explore the mechanism by which sIL-2Rα may contribute to a poor prognosis in FL, we determined the effects of sIL-2Rα on IL-2 signaling and found that the sIL-2Rα-IL-2 complex promoted T-cell differentiation toward to inhibitory T(reg) cells rather than T(H)1 or T(H)17 cells. Shed by activated T cells that express membrane-bound IL-2Rα, sIL-2Rα further enhanced IL-2-mediated phosphorylation of Stat5 thereby significantly up-regulating Foxp3 expression in CD4(+) T cells. We found that CD4(+) T cells treated with either IL-2 or sIL-2Rα-IL-2 complex, but not with sIL-2Rα alone, inhibited the function of CD8(+) T cells. Taken together, these results indicate that sIL-2Rα actually plays an active biologic role in FL by binding IL-2 and promoting IL-2 signaling rather than depleting IL-2 and blocking its function.

GATA-3 expression identifies a high-risk subset of PTCL, NOS with distinct molecular and clinical features.

The cell of origin and the tumor microenvironments role remain elusive for the most common peripheral T-cell lymphomas (PTCLs). As macrophages promote the growth and survival of malignant T cells and are abundant constituents of the tumor microenvironment, their functional polarization was examined in T-cell lymphoproliferative disorders. Cytokines that are abundant within the tumor microenvironment, particularly interleukin (IL)-10, were observed to promote alternative macrophage polarization. Macrophage polarization was signal transducer and activator of transcription 3 dependent and was impaired by the Janus kinase inhibitor ruxolitinib. In conventional T cells, the production of T helper (Th)2-associated cytokines and IL-10, both of which promote alternative macrophage polarization, is regulated by the T-cell transcription factor GATA-binding protein 3 (GATA-3). Therefore, its role in the T-cell lymphomas was examined. GATA-3 expression was observed in 45% of PTCLs, not otherwise specified (PTCL, NOS) and was associated with distinct molecular features, including the production of Th2-associated cytokines. In addition, GATA-3 expression identified a subset of PTCL, NOS with distinct clinical features, including inferior progression-free and overall survival. Collectively, these data suggest that further understanding the cell of origin and lymphocyte ontogeny among the T-cell lymphomas may improve our understanding of the tumor microenvironments pathogenic role in these aggressive lymphomas.

A BAFF-R mutation associated with non-Hodgkin lymphoma alters TRAF recruitment and reveals new insights into BAFF-R signaling.

A BAFF receptor mutation associated with non-Hodgkin lymphoma provides new insight into the proximal players of normal BAFF-R signaling.