Heather M. Gibson

Immune function abnormalities in peripheral blood mononuclear cell cytokine expression differentiates stages of cutaneous T-cell lymphoma/mycosis fungoides

Purpose: Mycosis fungoides (MF) is a cutaneous T-cell lymphoma (CTCL) characterized by neoplastic skin-homing T cells. To better understand the immunopathogenesis of MF, we analyzed the functional ability of peripheral blood mononuclear cells (PBMC) from early and late MF/CTCL patients to express cytokine genes. In late stage MF/CTCL, patients were separated into those with blood involvement (+B) and without blood involvement (−B). Experimental Design: We analyzed TH1 (interleukin 2 (IL-2), IFN-γ), TH2 (IL-4, IL-5, IL-10, IL-13), and TH17 (IL-17) cytokine gene expression from activated PBMCs from normal (n = 12), psoriasis (n = 6), early MF/CTCL (n = 11), and late MF/CTCL+B (n = 4) and MF/CTCL−B (n = 3) by quantitative real-time PCR. Results: PBMCs from early MF/CTCL and psoriasis showed higher induction of IL-2, IL-4, and IFN-γ genes than those from normal and late MF/CTCL−B and MF/CTCL+B (P < 0.05) in descending order. PBMCs from late MF/CTCL−B exhibited generally the highest level of IL-5, IL-10, IL-13, and IL-17 expression compared with the other groups. PBMCs from early MF/CTCL and late MF/CTCL−B had similarly elevated IL-13 and IL-17. Of all groups, PBMCs from late MF/CTCL+B had the lowest levels of IL-2 (P < 0.05), IL-4, IFN-γ, IL-13, and IL-17. Conclusions: The different pattern of cytokine gene expression suggests a change in immune function in MF/CTCL from early MF/CTCL to late MF/CTCL−B to late MF/CTCL+B. These stages are consistent with localized disease associated with an anti-tumor immune response and late MF/CTCL associated with a loss of immune function mediated by malignant T cells that share regulatory T cell–like properties.

Induction of the CTLA-4 gene in human lymphocytes is dependent on NFAT binding the proximal promoter.

CTLA-4 is a member of the costimulatory family, has homology to CD28, and binds the B7 family of ligands. Unlike CD28, CTLA-4 ligation transmits a negative signal in T cells. CTLA-4 expression, while inducible in most T cells, is expressed constitutively on T cells with a regulatory phenotype. The mechanism controlling CTLA-4 expression in human T cells is poorly characterized, thus we sought to better understand the mechanism of activation of the CTLA-4 gene. By cloning the 5′ upstream promoter and creating promoter-deletion reporter constructs, we show that the proximal promoter is critical for activating the CTLA-4 gene. Within this region, we identify a NFAT consensus sequence that binds NFAT with high affinity that differs from other NFAT sequences and does not recruit AP-1. Analysis of the chromatin proteins in the native CTLA-4 gene shows that this promoter region becomes associated with acetylated histones by chromatin immunoprecipitation assays. In addition, NFAT1 binds to the promoter of the CTLA-4 gene after stimulation by chromatin immunoprecipitation. The functional requirement of the NFAT site for CTLA-4 transcription was demonstrated by mutations in the NFAT site that abolished the activity of the promoter. Furthermore, inhibitors of NFAT suppressed CTLA-4 gene expression, indicating that NFAT plays a critical role in regulating the induction of the CTLA-4 gene in lymphocytes. The identification of NFAT as a critical regulator of the CTLA-4 gene suggests that targeting NFAT function may lead to novel approaches to modulate the CTLA-4 gene to control the immune response.

Differential CTLA-4 expression in human CD4+ versus CD8+ T cells is associated with increased NFAT1 and inhibition of CD4+ proliferation

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a costimulatory molecule that negatively regulates T-cell activation. Originally identified in murine CD8+ T cells, it has been found to be rapidly induced on human T cells. Furthermore, CTLA-4 is expressed on regulatory T cells. Clinically, targeting CTLA-4 has clinical utility in the treatment of melanoma. Whether the expression of CTLA-4 is differentially regulated in CD8+ vs CD4+ human T cells is unclear. Here, we analyzed CTLA-4 in normal human CD4+ and CD8+ T-cell subsets and show for the first time that CTLA-4 is expressed significantly higher in the CD4+ T cells than in CD8+ T cells. CTLA-4 is higher at the protein and the transcriptional levels in CD4+ T cells. This increase is due to the activation of the CTLA-4 promoter, which undergoes acetylation at the proximal promoter. Furthermore, we show that blocking CTLA-4 on CD4+ T cells permits greater proliferation in CD4+ vs CD8+ cells. These findings demonstrate a differential regulation of CTLA-4 on CD4+ and CD8+ T-cell subsets, which is likely important to the clinical efficacy for anti-CTLA-4 therapies. The findings hint to strategies to modulate CTLA-4 expression by targeting epigenetic transcription to alter the immune response.

T-plastin (PLS3) gene expression differentiates Sézary syndrome from mycosis fungoides and inflammatory skin diseases and can serve as a biomarker to monitor disease progression

Background Cutaneous T-cell lymphoma (CTCL) is a group of lymphoproliferative disorders that includes mycosis fungoides (MF) and Sezary syndrome (SS). T-Plastin (PLS3) is an actin-bundling protein that has been found to be highly expressed in Sezary cells but not in normal PBMCs. Here, we describe the value of using PLS3 as a sensitive molecular marker for differentiating stages of MF from SS, and for monitoring development of SS from MF.

Impaired Proteasome Function Activates GATA3 in T Cells and Upregulates CTLA-4: Relevance for Sézary Syndrome

Highly regulated expression of the negative costimulatory molecule cytotoxic T-lymphocyte antigen-4 (CTLA-4) on T cells modulates T-cell activation and proliferation. CTLA-4 is preferentially expressed in Th2 T cells, whose differentiation depends on the transcriptional regulator GATA3. Sézary syndrome (SS) is a T-cell malignancy characterized by Th2 cytokine skewing, impaired T-cell responses, and overexpression of GATA3 and CTLA-4. GATA3 is regulated by phosphorylation and ubiquitination. In SS cells, we detected increased polyubiquitinated proteins and activated GATA3. We hypothesized that proteasome dysfunction in SS T cells may lead to GATA3 and CTLA-4 overexpression. To test this hypothesis, we blocked proteasome function with bortezomib in normal T cells, and observed sustained GATA3 and CTLA-4 upregulation. The increased CTLA-4 was functionally inhibitory in a mixed lymphocyte reaction (MLR). GATA3 directly transactivated the CTLA-4 promoter, and knockdown of GATA3 messenger RNA and protein inhibited CTLA-4 induction mediated by bortezomib. Finally, knockdown of GATA3 in patients malignant T cells suppressed CTLA-4 expression. Here we demonstrate a new T-cell regulatory pathway that directly links decreased proteasome degradation of GATA3, CTLA-4 upregulation, and inhibition of T-cell responses. We also demonstrate the requirement of the GATA3/CTLA-4 regulatory pathway in fresh neoplastic CD4+ T cells. Targeting of this pathway may be beneficial in SS and other CTLA-4-overexpressing T-cell neoplasms.

Cryotherapy with Concurrent CpG Oligonucleotide Treatment Controls Local Tumor Recurrence and Modulates HER2/neu Immunity

Percutaneous cryoablation is a minimally invasive procedure for tumor destruction, which can potentially initiate or amplify antitumor immunity through the release of tumor-associated antigens. However, clinically efficacious immunity is lacking and regional recurrences are a limiting factor relative to surgical excision. To understand the mechanism of immune activation by cryoablation, comprehensive analyses of innate immunity and HER2/neu humoral and cellular immunity following cryoablation with or without peritumoral CpG injection were conducted using two HER2/neu(+) tumor systems in wild-type (WT), neu-tolerant, and SCID mice. Cryoablation of neu(+) TUBO tumor in BALB/c mice resulted in systemic immune priming, but not in neu-tolerant BALB NeuT mice. Cryoablation of human HER2(+) D2F2/E2 tumor enabled the functionality of tumor-induced immunity, but secondary tumors were refractory to antitumor immunity if rechallenge occurred during the resolution phase of the cryoablated tumor. A step-wise increase in local recurrence was observed in WT, neu-tolerant, and SCID mice, indicating a role of adaptive immunity in controlling residual tumor foci. Importantly, local recurrences were eliminated or greatly reduced in WT, neu tolerant, and SCID mice when CpG was incorporated in the cryoablation regimen, showing significant local control by innate immunity. For long-term protection, however, adaptive immunity was required because most SCID mice eventually succumbed to local tumor recurrence even with combined cryoablation and CpG treatment. This improved understanding of the mechanisms by which cryoablation affects innate and adaptive immunity will help guide appropriate combination of therapeutic interventions to improve treatment outcomes.

IFNγ PET Imaging as a Predictive Tool for Monitoring Response to Tumor Immunotherapy

IFNγ is an attractive target for imaging active antitumor immunity due to its function in the T-cell signaling axis. Here, we test an IFNγ immuno-PET (immunoPET) probe for its capacity to identify adaptive immunotherapy response after HER2/neu vaccination in both spontaneous salivary and orthotopic neu+ mouse mammary tumors. IFNγ immunoPET detected elevated cytokine levels in situ after vaccination, which inversely correlated with tumor growth rate, an indicator of response to therapy. In a model of induced T-cell anergy where CD8 T cells infiltrate the tumor, but upregulate PD-1, IFNγ tracer uptake was equivalent to isotype control, illustrating a lack of antitumor T-cell activity. The IFNγ immunoPET tracer detected IFNγ protein sequestered on the surface of tumor cells, likely in complex with the IFNγ receptor, which may explain imaging localization of this soluble factor in vivo Collectively, we find that the activation status of cytotoxic T cells is annotated by IFNγ immunoPET, with reduced off-target binding to secondary lymphoid tissues compared with imaging total CD3+ tumor-infiltrating lymphocytes. Targeting of soluble cytokines such as IFNγ by PET imaging may provide valuable noninvasive insight into the function of immune cells in situ Significance: This study presents a novel approach to monitor therapeutic outcomes via IFNγ-targeted positron emission tomography. Cancer Res; 78(19); 5706-17. ©2018 AACR.

Abstract 3857: Targeting HDAC1 in a novel model of cutaneous T-cell lymphoma.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Cutaneous T-cell lymphoma (CTCL) is a type of non-Hodgkins lymphoma composed of a spectrum of diseases of malignant clonal helper CD4+ T lymphocytes. Previous studies have shown that IL-15 acts as viability factor for CTCL cells, inhibiting apoptosis, and may work in association with other factors to maintain the malignant infiltrate in the epidermis. IL-15 is highly expressed both at mRNA and protein levels in the skin of CTCL patients. Using an IL-15 transgenic (tg) mouse model for spontaneous CTCL that clinically and pathologically mimics the human malignancy, we described a system for studying lymphomagenesis in CTCL (97th Annual Meeting of the AACR; 2010. Abstract nr. 2858). Skin lesions in these mice revealed the presence of characteristic Pautriers microabscesses and these mice had poor survival. Cutaneous CD4+ T-cells from these mice were capable of engrafting into the skin of secondary SCID recipients, producing histological lesions of similar pathology. Consistent with human CTCL, we found that these tg mice are predominantly CD62L- (P=0.0009, N=14) with overexpression of CCR4, CLA, and CD44 (P=0.0001, N=14). Interestingly, we also observed elevated histone deacetylase-1 (Hdac1) expression in IL-15 tg mice compared to the wild type (WT) cohort (P=0.0013, N=3). We hypothesized that IL-15 regulates epigenetic changes in normal CD4+ lymphocytes by modulating Hdac1 and Hdac6. We analyzed normal human- and WT mouse- CD4+ T-cells and found that IL-15 induces upregulation of Hdac1 protein and cytoplasmic translocalization of Hdac6. To elucidate the mechanism controlling Hdac1 induction, we tested whether IL-15 stimulation leads to autoregulation of Hdac1 in vitro. Chromatin immunoprecipitation (ChIP) PCR analysis of IL-15 stimulated CD4+ T-cells revealed that Hdac1 binds to its own promoter as early as 12 hours post incubation increasing its own transcription. Similar observations were made in CD4+ T-cells from CTCL patients when compared to normal donor CD4+ T-cells suggesting that Hdac1 could be upregulated in CD4+ T-cells as a result of autoregulation from endogenous IL-15. To test Hdac-inhibitor therapy in IL-15 tg CTCL mice, we performed a randomized, placebo-controlled trial of an oral HDAC inhibitor invented at The Ohio State University, AR-42 (Arno Therapeutics Inc., Flemington, NJ). Interestingly, 100% of mice treated with AR-42 showed clinical improvement and reduced dermal lymphocytic infiltration after the treatment when compared to the placebo arm. In summary, our study provides a murine model of spontaneous CTCL that mimics the human disease, and also, demonstrate for the first time IL-15 mediated autoregulation of a histone-modifying enzyme Hdac1 in CD4+ T-cells that may contribute towards pathogenesis of CTCL. Finally, we show that AR-42 has significant efficacy in this preclinical CTCL model, which has in part paved the way for its current evaluation in a Phase I human clinical trial. Citation Format: Anjali Mishra, Laura Sullivan, Gregory Sams, Jessica Johns, Douglas Curphey, Lauren Falkenberg, Heather Gibson, Shujun Liu, Laura Jaroncyk, Kathleen McConnell, Henry Wong, Krista La Perle, Ramiro Garzon, Guido Marcucci, Pierluigi Porcu, Michael Caligiuri. Targeting HDAC1 in a novel model of cutaneous T-cell lymphoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3857. doi:10.1158/1538-7445.AM2013-3857

Abstract 2858: A novel mouse model for cutaneous T-cell lymphoma reveals a role for IL-15 and activity of a new oral HDAC inhibitor

Cutaneous T-cell lymphoma (CTCL) is a type of non-Hodgkin9s lymphoma representing a spectrum of diseases composed of malignant clonal CD4 (+) helper T lymphocytes. The etiology of CTCL remains to be elucidated and no animal models for CTCL are known. We quantified expression of IL-15 in patients with CTCL and demonstrated aberrant overexpression of IL-15 compared to normal CD4+ T cells (Fold increase = 7.476 ± 1.788 N=3, P=0.0073), that showed direct correlation with the stage of the disease (Fold increase in IL-15 in Stage I patients vs. Stage III patients = 3.283 ± 0.8246 vs. 7.476 ± 1.788, N=3 each, P=0.02). We engineered a transgenic (tg) mouse to constitutively and globally overexpress murine IL-15. These mice develop alopecia and cutaneous lesions in all mice within 6 weeks of birth, characterized by erythematous plaques/patches, erythroderma, pruritis and early death compared to wild type (WT) controls (49 weeks vs. 100 weeks, P=0.0003). Skin lesions showed an infiltration of atypical lymphocyte in the dermis and throughout the epidermis including the formation of classic Pautrier9s microabscesses as seen in human CTCL. Immunophenotypic analysis of the skin T-cells from these mice revealed ∼25 fold increase in CD3+ T-cells compared to WT littermates. Intradermal CD4+ cells from CTCL mice were predominantly CD62L- and significantly higher than WT mice (P=0.007). Immunohistochemistry showed high expression of cutaneous lymphocyte antigen (CLA) and CCR4 on skin sections of CTCL mice, consistent with a skin-specific homing pattern as seen in human CTCL. Cells obtained from the skin of these IL-15tg CTCL mice could be successfully engrafted into skin of SCID recipient mice with reproducible histological lesions. Consistent with human studies, CTCL mice exhibited significantly increased levels of Hdac-1 in CD4+ T cells when compared to their WT counterparts (P = 0.0013). To investigate the importance of IL-15 in this process, we cultured sorted mouse WT (CD3+CD4+) T-cells in medium supplemented with 100ng/ml IL-15 and observed a significant increase in Hdac-1 expression at the mRNA and protein level within 10 days of culture, compared to freshly isolated WT CD4+ T cells (N=3 each, p =0.02). In a randomized, placebo-controlled trial of an orally administered novel HDAC inhibitor, AR-42 (Arno Therapeutics, Inc, Parsippany, NJ; Sargeant AM et al, Cancer Research, 2008) to IL-15 tg mice with CTCL, we observed an improvement in skin lesions and a marked reduction in T-cell dermal infiltrate as early as 12 days post-treatment. In conclusion, we provide evidence for a reproducible in vivo mouse model of spontaneous CTCL that appears to mimic the human condition. Further, we provide evidence for a role of aberrant IL-15 expression in the genesis of both human and experimental CTCL, and alterations in Hdac-1 expression that may to serve as an appropriate target for a novel oral HDAC inhibitor now in clinical trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2858. doi:10.1158/1538-7445.AM2011-2858