Malignant Tregs express low molecular splice forms of FOXP3 in Sézary syndrome

Pneumocystis jirovecii Pneumonia in a Patient With Localized Mycosis Fungoides Not Receiving Immunosuppressive Treatment

Pneumocystis jirovecii pneumonia (PCP) is the most common opportunistic infection in patients with human immunodeficiency virus (HIV), but it may develop in patients without HIV, whose immune system is suppressed by anticancer or immunosuppressive agents even when indicating normal counts of CD4+ T cells. Mycosis fungoides (MF) is a primary cutaneous T-cell lymphoma, which is believed not to cause immunosuppressive conditions unless it develops leukosis or metastasis or is treated with anticancer drugs or systemic immunosuppressants. Here, we report a case of PCP in a patient with localized MF not receiving immunosuppressive treatment. The patient, a woman in her 70s, presented with persistent dyspnea. High-resolution computed tomography (HRCT) showed diffuse ground-glass opacities in both lungs. Bronchoalveolar lavage fluid was positive for P. jirovecii. Moreover, the cytomegalovirus antigenemia test was positive, whereas tests for anti-HIV and antihuman T-cell lymphotropic virus antibodies were negative. The patient was treated with trimethoprim-sulfamethoxazole, prednisolone, and ganciclovir, which gradually improved the symptoms and diminished diffuse ground-glass opacities on HRCT. This case exemplifies a rare presentation of PCP with mild MF that was not treated with chemotherapy or immunosuppressants. The possible mechanisms for the development of PCP are discussed.

Blockade of the Immune Checkpoint CD47 by TTI-621 Potentiates the Response to Anti-PD-L1 in Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is an incurable and cosmetically disfiguring disease associated with microenvironmental signals. We investigated the effects of CD47 and PD-L1 immune checkpoint blockades, as a strategy for targeting both innate and adaptive immunity. CIBERSORT analysis identified the immune-cell composition in the CTCL tumor microenvironment and the immune checkpoint expression profile for each immune-cell gene cluster from CTCL lesions. We investigated the relationship between MYC and CD47 and PD-L1 expression and found that MYC short hairpin RNA knockdown and MYC functional suppression by TTI-621 (SIRPαFc) and anti-PD-L1 (durvalumab) in CTCL cell lines reduced the expression of CD47 and PDL1 mRNA and protein as measured by qPCR and flow cytometry, respectively. In vitro, blockade of the CD47-SIRPα interaction with TTI-621 increased the phagocytic activity of macrophages against CTCL cells and enhanced CD8+ T-cell-mediated killing in a mixed leucocyte reaction. Moreover, TTI-621 synergized with anti-PD-L1 in macrophages reprogram to M1-like phenotypes and inhibited CTCL cell growth. These effects were mediated by cell death-related pathways, including apoptosis, autophagy, and necroptosis. Collectively, our findings show that CD47 and PD-L1 are critical regulators of immune surveillance in CTCL and that dual targeting of CD47 and PD-L1 will provide insight into tumor immunotherapy for CTCL.

Spatially Guided and Single Cell Tools to Map the Microenvironment in Cutaneous T-Cell Lymphoma

Mycosis fungoides (MF) and Sézary syndrome (SS) are two closely related clinical variants of cutaneous T-cell lymphomas (CTCL). Previously demonstrated large patient-to-patient and intra-patient disease heterogeneity underpins the importance of personalized medicine in CTCL. Advanced stages of CTCL are characterized by dismal prognosis, and the early identification of patients who will progress remains a clinical unmet need. While the exact molecular events underlying disease progression are poorly resolved, the tumor microenvironment (TME) has emerged as an important driver. In particular, the Th1-to-Th2 shift in the immune response is now commonly identified across advanced-stage CTCL patients. Herein, we summarize the role of the TME in CTCL evolution and the latest studies in deciphering inter- and intra-patient heterogeneity. We introduce spatially resolved omics as a promising technology to advance immune-oncology efforts in CTCL. We propose the combined implementation of spatially guided and single-cell omics technologies in paired skin and blood samples. Such an approach will mediate in-depth profiling of phenotypic and molecular changes in reactive immune subpopulations and malignant T cells preceding the Th1-to-Th2 shift and reveal mechanisms underlying disease progression from skin-limited to systemic disease that collectively will lead to the discovery of novel biomarkers to improve patient prognostication and the design of personalized treatment strategies.

Pathogenic role of Th17 cells in autoimmune thyroid disease and their underlying mechanisms

Autoimmune thyroid disease, encompassing Graves' disease and Hashimoto's thyroiditis, has a very complex etiology. Pathogenesis of the disease involves both genetic susceptibility and environmental triggers. Traditionally, imbalance of T helper cell 1 and 2 was thought to result in the immune disorders in Graves' disease and Hashimoto's thyroiditis. However, increasing evidence recently revealed the important role of T helper 17 cell and its relative cellular and secretory components in the pathogenesis and progression of autoimmune thyroid disease. This review is aimed to summarize the published studies on the involvement of T helper 17 cell in autoimmune thyroid disease and discuss the underlying regulatory mechanisms, which could possibly serve as the foundation of discovering new therapeutic targets.

Single-cell analysis of Sézary syndrome reveals novel markers and shifting gene profiles associated with treatment

Cutaneous T-cell lymphomas (CTCLs) are a spectrum of diseases with varied clinical courses caused by malignant clonal proliferation of skin-tropic T cells. Most patients have an indolent disease course managed with skin-directed therapies. In contrast, others, especially in advanced stages of disease or with specific forms, have aggressive progression and poor median survival. Sézary syndrome (SS), a leukemic variant of CTCL, lacks highly consistent phenotypic and genetic markers that may be leveraged to prevent the delay in diagnosis experienced by most patients with CTCL and could be useful for optimal treatment selection. Using single-cell mRNA and T-cell receptor sequencing of peripheral blood immune cells in SS, we extensively mapped the transcriptomic variations of nearly 50 000 T cells of both malignant and nonmalignant origins. We identified potential diverging SS cell populations, including quiescent and proliferative populations shared across multiple patients. In particular, the expression of AIRE was the most highly upregulated gene in our analysis, and AIRE protein expression could be observed over a variety of CTCLs. Furthermore, within a single patient, we were able to characterize differences in cell populations by comparing malignant T cells over the course of treatment with histone deacetylase inhibition and photopheresis. New cellular clusters after progression of the therapy notably exhibited increased expression of the transcriptional factor FOXP3, a master regulator of regulatory T-cell function, raising the potential implication of an evolving mechanism of immune evasion.

Molecular pathogenesis of Cutaneous T cell Lymphoma: Role of chemokines, cytokines, and dysregulated signaling pathways

Cutaneous T cell lymphomas (CTCLs) are a heterogeneous group of lymphoproliferative neoplasms that exhibit a wide spectrum of immune-phenotypical, clinical, and histopathological features. The biology of CTCL is complex and remains elusive. In recent years, the application of next-generation sequencing (NGS) has evolved our understanding of the pathogenetic mechanisms, including genetic aberrations and epigenetic abnormalities that shape the mutational landscape of CTCL and represent one of the important pro-tumorigenic principles in CTCL initiation and progression. Still, identification of the major pathophysiological pathways including genetic and epigenetic components that mediate malignant clonal T cell expansion has not been achieved. This is of prime importance given the role of malignant T cell clones in fostering T helper 2 (Th2)-bias tumor microenvironment and fueling progressive immune dysregulation and tumor cell growth in CTCL patients, manifested by the secretion of Th2-associated cytokines and chemokines. Alterations in malignant cytokine and chemokine expression patterns orchestrate the inflammatory milieu and influence the migration dynamics of malignant clonal T cells. Here, we highlight recent insights about the molecular mechanisms of CTCL pathogenesis, emphasizing the role of cytokines, chemokines, and associated downstream signaling networks in driving immune defects, malignant transformation, and disease progression. In-depth characterization of the CTCL immunophenotype and tumoral microenvironment offers a facile opportunity to expand the therapeutic armamentarium of CTCL, an intractable malignant skin disease with poor prognosis and in dire need of curative treatment approaches.

Concomitant Inhibition of FASN and SREBP Provides a Promising Therapy for CTCL

Simple Summary

The biosynthesis of fatty acids catalysed by FASN plays an important oncogenic role in various malignancies but has not been reported in CTCL yet. Here, we show that FASN is highly expressed in both cell lines and primary cells from CTCL patients. The inhibition of FASN impairs cell viability, survival, and proliferation. FASN expression is partly controlled by SREBP, and dual inhibition of FASN and SREBP enhances the impairment of cell proliferation. Overall, our data suggest that the combination of FASN and SREBP inhibitors could be a promising novel strategy in CTCL therapy.

Abstract

Cutaneous T cell lymphoma (CTCL) is a group of non-Hodgkin’s primary cutaneous T cell lymphomas, with Mycosis Fungoides and Sézary syndrome (SS) being the two most common subtypes. Fatty acid synthase (FASN) is a crucial enzyme that catalyses the biosynthesis of fatty acids, which has been reported to play an oncogenic role in various malignancies but not in CTCL so far. Herein, we show that FASN is highly expressed in CTCL cell lines and in peripheral blood mononuclear cells (PBMCs) from CTCL patients, while it is not in PBMCs from healthy individuals. The inhibition of FASN in CTCL cell lines impairs cell viability, survival, and proliferation, but, interestingly, it also increases FASN expression. However, inhibiting sterol regulatory element binding protein (SREBP), a transcription factor that promotes the expression of FASN, partially reversed the upregulation of FASN induced by FASN inhibitors. Thus, the combination of FASN and SREBP inhibitors enhanced the effects on both CTCL cell lines and PBMCs from SS patients, where a valid inhibition on cell proliferation could be verified. Importantly, compared to non-malignant cells, primary malignant cells are more sensitive to the inhibition of FASN and SREBP, making the combination of FASN and SREBP inhibitors a promising novel therapeutic strategy in CTCL.

The Role of Tumor Microenvironment in the Pathogenesis of Sézary Syndrome

Sézary syndrome is an aggressive leukemic variant of cutaneous T-cell lymphomas, characterized by erythroderma, lymphadenopathy, and peripheral blood involvement by CD4+ malignant T-cells. The pathogenesis of Sézary syndrome is not fully understood. However, the course of the disease is strongly influenced by the tumor microenvironment, which is altered by a combination of cytokines, chemokines, and growth factors. The crosstalk between malignant and reactive cells affects the immunologic response against tumor cells causing immune dysregulation. This review focuses on the interaction of malignant Sézary cells and the tumor microenvironment.

Mogamulizumab efficacy is underscored by its associated rash that mimics cutaneous T-cell lymphoma: a retrospective single-centre case series

BACKGROUND

Mogamulizumab is a humanized antibody against chemokine receptor type 4. It was recently approved by the US Food and Drug Administration for relapsed or refractory mycosis fungoides (MF) and Sézary syndrome (SS). The most commonly reported adverse event in the phase III licensing trial was drug eruption (28%), now termed mogamulizumab-associated rash (MAR). Clinical recommendations about MAR and its treatment differ between the current package insert and postapproval insights reported from two single-centre studies that focused on its characterization, but less so on outcomes and clinicopathological differentiation from cutaneous T-cell lymphoma (CTCL).

OBJECTIVES

To describe our experience in the diagnosis of MAR and treatment of patients with CTCL with mogamulizumab.

METHODS

This is a single-centre retrospective case series study.

RESULTS

We found a higher incidence of MAR in patients with CTCL (17 of 24, 68%) than previously reported. MAR development is associated with complete (11 of 17) or partial (four of 17) responses, with an overall response rate of 88%, compared with 29% (two of seven) in patients without MAR. Diagnosis of MAR may be obscured by its ability to mimic key CTCL features both clinically and histologically, but an absence of T-cell-receptor clonality and relatively decreased CD4 : CD8 ratio compared with baseline lesions strongly favour MAR over recurrent disease.

CONCLUSIONS

MAR has the potential to create a significant management problem for patients on mogamulizumab. Misidentification of MAR as recurrent CTCL may detrimentally result in the premature discontinuation of mogamulizumab in patients whose disease is historically hard to treat. Thorough clinicopathological investigation of new lesions during treatment with mogamulizumab is required to inform ideal treatment decisions and achieve better outcomes.

High Expression of IKZF2 in Malignant T Cells Promotes Disease Progression in Cutaneous T Cell Lymphoma

Cutaneous T cell lymphoma is a generally indolent disease derived from skin-homing mature T cells. However, in advanced stages, cutaneous T cell lymphoma may manifest aggressive clinical behaviour and lead to a poor prognosis. The mechanism of disease progression in cutaneous T cell lymphoma remains unknown. This study, based on a large clinical cohort, found that IKZF2, an essential transcription factor during T cell development and differentiation, showed stage-dependent overexpression in the malignant T cells in mycosis fungoides lesions. IKZF2 is specifically over-expressed in advanced-stage mycosis fungoides lesions, and correlates with poor prognosis. Mechanistically, overexpression of IKZF2 promotes cutaneous T cell lymphoma progression via inhibiting malignant cell apoptosis and may contribute to tumour immune escape by downregulating major histocompatibility complex II molecules and up-regulating the production of anti-inflammatory cytokine interleukin-10 by malignant T cells. These results demonstrate the important role of IKZF2 in high-risk cutaneous T cell lymphoma and pave the way for future targeted therapy.

Sequence determinants as key regulators in gene expression of T cells

T cell homeostasis, T cell differentiation, and T cell effector function rely on the constant fine-tuning of gene expression. To alter the T cell state, substantial remodeling of the proteome is required. This remodeling depends on the intricate interplay of regulatory mechanisms, including post-transcriptional gene regulation. In this review, we discuss how the sequence of a transcript influences these post-transcriptional events. In particular, we review how sequence determinants such as sequence conservation, GC content, and chemical modifications define the levels of the mRNA and the protein in a T cell. We describe the effect of different forms of alternative splicing on mRNA expression and protein production, and their effect on subcellular localization. In addition, we discuss the role of sequences and structures as binding hubs for miRNAs and RNA-binding proteins in T cells. The review thus highlights how the intimate interplay of post-transcriptional mechanisms dictate cellular fate decisions in T cells.

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.

Staphylococcus aureus enterotoxins induce FOXP3 in neoplastic T cells in Sézary syndrome

Sézary syndrome (SS) is a heterogeneous leukemic subtype of cutaneous T-cell lymphoma (CTCL) with generalized erythroderma, lymphadenopathy, and a poor prognosis. Advanced disease is invariably associated with severe immune dysregulation and the majority of patients die from infectious complications caused by microorganisms such as, Staphylococcus aureus, rather than from the lymphoma per se. Here, we examined if staphylococcal enterotoxins (SE) may shape the phenotype of malignant SS cells, including expression of the regulatory T-cell-associated marker FOXP3. Our studies with primary and cultured malignant cells show that SE induce expression of FOXP3 in malignant cells when exposed to nonmalignant cells. Mutations in the MHC class II binding domain of SE-A (SEA) largely block the effect indicating that the response relies at least in part on the MHC class II-mediated antigen presentation. Transwell experiments show that the effect is induced by soluble factors, partly blocked by anti-IL-2 antibody, and depends on STAT5 activation in malignant cells. Collectively, these findings show that SE stimulate nonmalignant cells to induce FOXP3 expression in malignant cells. Thus, differences in exposure to environmental factors, such as bacterial toxins may explain the heterogeneous FOXP3 expression in malignant cells in SS.

Colorectal cancer cell-derived CCL20 recruits regulatory T cells to promote chemoresistance via FOXO1/CEBPB/NF-κB signaling

Background

Colorectal cancer (CRC) is one of the most common forms of cancer worldwide. The tumor microenvironment plays a key role in promoting the occurrence of chemoresistance in solid cancers. Effective targets to overcome resistance are necessary to improve the survival and prognosis of CRC patients. This study aimed to evaluate the molecular mechanisms of the tumor microenvironment that might be involved in chemoresistance in patients with CRC.

Methods

We evaluated the effects of CCL20 on chemoresistance of CRC by recruitment of regulatory T cells (Tregs) in vitro and in vivo.

Results

We found that the level of CCL20 derived from tumor cells was significantly higher in Folfox-resistant patients than in Folfox-sensitive patients. The high level of CCL20 was closely associated with chemoresistance and poor survival in CRC patients. Among the drugs in Folfox chemotherapy, we confirmed that 5-FU increased the expression of CCL20 in CRC. Moreover, CCL20 derived from 5-FU-resistant CRC cells promoted recruitment of Tregs. Tregs further enhanced the chemoresistance of CRC cells to 5-FU. FOXO1/CEBPB/NF-κB signaling was activated in CRC cells after 5-FU treatment and was required for CCL20 upregulation mediated by 5-FU. Furthermore, CCL20 blockade suppressed tumor progression and restored 5-FU sensitivity in CRC. Lastly, the expression of these signaling molecules mediating chemoresistance was closely correlated with poor survival of CRC patients.

Conclusions

CRC cell-secreted CCL20 can recruit Tregs to promote chemoresistance via FOXO1/CEBPB/NF-κB signaling, indicating that the FOXO1/CEBPB/NF-κB/CCL20 axis might provide a promising target for CRC treatment.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0701-2) contains supplementary material, which is available to authorized users.

Single-Cell Profiling of Cutaneous T-Cell Lymphoma Reveals Underlying Heterogeneity Associated with Disease Progression

PURPOSE

Cutaneous T-cell lymphomas (CTCL), encompassing a spectrum of T-cell lymphoproliferative disorders involving the skin, have collectively increased in incidence over the last 40 years. Sézary syndrome is an aggressive form of CTCL characterized by significant presence of malignant cells in both the blood and skin. The guarded prognosis for Sézary syndrome reflects a lack of reliably effective therapy, due, in part, to an incomplete understanding of disease pathogenesis.

EXPERIMENTAL DESIGN

Using single-cell sequencing of RNA and the machine-learning reverse graph embedding approach in the Monocle package, we defined a model featuring distinct transcriptomic states within Sézary syndrome. Gene expression used to differentiate the unique transcriptional states were further used to develop a boosted tree classification for early versus late CTCL disease.

RESULTS

Our analysis showed the involvement of FOXP3 + malignant T cells during clonal evolution, transitioning from FOXP3 + T cells to GATA3 + or IKZF2 + (HELIOS) tumor cells. Transcriptomic diversities in a clonal tumor can be used to predict disease stage, and we were able to characterize a gene signature that predicts disease stage with close to 80% accuracy. FOXP3 was found to be the most important factor to predict early disease in CTCL, along with another 19 genes used to predict CTCL stage.

CONCLUSIONS

This work offers insight into the heterogeneity of Sézary syndrome, providing better understanding of the transcriptomic diversities within a clonal tumor. This transcriptional heterogeneity can predict tumor stage and thereby offer guidance for therapy.

Highly cytotoxic natural killer cells are associated with poor prognosis in patients with cutaneous T-cell lymphoma

Paradoxically higher NK-cell activity in CTCL patients is associated with increased expression of phosphorylated STAT5. These highly effective NK cells are associated with poor prognosis in patients with leukemic CTCL.

Intratumoral FOXP3+ Regulatory T Cells in Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma in Egypt and worldwide. Gene expression profiling classifies DLBCL into: germinal center B cell-like (GCB) and non germinal center B cell-like (non-GCB) DLBCL. Hans' algorithm has high concordance with gene expression profiling results. Regulatory T cells (Tregs) represent important modulators for the interaction between lymphoma cells and host microenvironment. FOXP3 is a popular single marker for Tregs. There is little information about the possible role of Tregs in high-grade lymphoma such as DLBCL. This study aims to assess the prognostic impact of FOXP3+ Tregs in DLBCL. The study was carried out on 70 archival cases (61 de novo DLBCL and 9 reactive follicular hyperplasia cases). DLBCL cases were classified into GCB and non-GCB groups using Hans' algorithm. All studied cases are subjected to FOXP3 immunostaining. Density of FOXP3+ Tregs was higher in reactive cases compared with DLBCL (P=0.000). In DLBCL cases, FOXP3 expression was associated with free spleen (P=0.02), early stage (P=0.05), centroblastic variant (P=0.003), and absence of necrosis (P=0.05). In germinal cases, density of FOXP3 was significantly higher in cases with good PS (P=0.02), very good and good revised international prognostic index (P=0.002), and low-risk age-adjusted international prognostic index >60 (P=0.01). Non germinal DLBCL cases with negative FOXP3 were significantly associated with splenic involvement (P=0.005). DLBCL cases with high FOXP3 have longer survival (P=0.03). T cells in the background of DLBCL may play a role in modulation of tumor progression. Their presence is associated with favorable prognostic parameters in DLBCL.

Alternative Splicing of FOXP3-Virtue and Vice

FOXP3 is the lineage-defining transcription factor of CD4+ CD25+ regulatory T cells. While many aspects of its regulation, interaction, and function are conserved among species, alternatively spliced FOXP3 isoforms are expressed only in human cells. This review summarizes current knowledge about alternative splicing of FOXP3 and the specific functions of FOXP3 isoforms in health and disease. Future perspectives in research and the therapeutic potential of manipulating alternative splicing of FOXP3 are discussed.

The role of regulatory T cells and genes involved in their differentiation in pathogenesis of selected inflammatory and neoplastic skin diseases. Part II: The Treg role in skin diseases pathogenesis

Regulatory FOXP3+ T cells (Tregs) constitute 5% to 10% of T cells in the normal human skin. They play an important role in the induction and maintenance of immunological tolerance. The suppressive effects of these cells are exerted by various mechanisms including the direct cytotoxic effect, anti-inflammatory cytokines, metabolic disruption, and modulation of the dendritic cells function. The deficiency of Treg cells number or function are one of the basic elements of the pathogenesis of many skin diseases, such as psoriasis, atopic dermatitis, bacterial and viral infections. They also play a role in the pathogenesis of T cell lymphomas of the skin (cutaneous T cell lymphomas - CTCL), skin tumors and mastocytosis. Here, in the second part of the cycle, we describe dysfunctions of Tregs in selected skin diseases.

Malignant inflammation in cutaneous T-cell lymphoma-a hostile takeover

Cutaneous T-cell lymphomas (CTCL) are characterized by the presence of chronically inflamed skin lesions containing malignant T cells. Early disease presents as limited skin patches or plaques and exhibits an indolent behavior. For many patients, the disease never progresses beyond this stage, but in approximately one third of patients, the disease becomes progressive, and the skin lesions start to expand and evolve. Eventually, overt tumors develop and the malignant T cells may disseminate to the blood, lymph nodes, bone marrow, and visceral organs, often with a fatal outcome. The transition from early indolent to progressive and advanced disease is accompanied by a significant shift in the nature of the tumor-associated inflammation. This shift does not appear to be an epiphenomenon but rather a critical step in disease progression. Emerging evidence supports that the malignant T cells take control of the inflammatory environment, suppressing cellular immunity and anti-tumor responses while promoting a chronic inflammatory milieu that fuels their own expansion. Here, we review the inflammatory changes associated with disease progression in CTCL and point to their wider relevance in other cancer contexts. We further define the term "malignant inflammation" as a pro-tumorigenic inflammatory environment orchestrated by the tumor cells and discuss some of the mechanisms driving the development of malignant inflammation in CTCL.

Jak3, STAT3, and STAT5 inhibit expression of miR-22, a novel tumor suppressor microRNA, in cutaneous T-Cell lymphoma

Aberrant activation of Janus kinase-3 (Jak3) and its key down-stream effectors, Signal Transducer and Activator of Transcription-3 (STAT3) and STAT5, is a key feature of malignant transformation in cutaneous T-cell lymphoma (CTCL). However, it remains only partially understood how Jak3/STAT activation promotes lymphomagenesis. Recently, non-coding microRNAs (miRNAs) have been implicated in the pathogenesis of this malignancy. Here, we show that (i) malignant T cells display a decreased expression of a tumor suppressor miRNA, miR-22, when compared to non-malignant T cells, (ii) STAT5 binds the promoter of the miR-22 host gene, and (iii) inhibition of Jak3, STAT3, and STAT5 triggers increased expression of pri-miR-22 and miR-22. Curcumin, a nutrient with anti-Jak3 activity and histone deacetylase inhibitors (HDACi) also trigger increased expression of pri-miR-22 and miR-22. Transfection of malignant T cells with recombinant miR-22 inhibits the expression of validated miR-22 targets including NCoA1, a transcriptional co-activator in others cancers, as well as HDAC6, MAX, MYCBP, PTEN, and CDK2, which have all been implicated in CTCL pathogenesis. In conclusion, we provide the first evidence that de-regulated Jak3/STAT3/STAT5 signalling in CTCL cells represses the expression of the gene encoding miR-22, a novel tumor suppressor miRNA.

Sézary Syndrome and Atopic Dermatitis: Comparison of Immunological Aspects and Targets

Sézary syndrome (SS), an aggressive form of erythrodermic pruritic cutaneous T cell lymphoma (CTCL), from an immunological perspective characterized by increased Th2 cytokine levels, elevated serum IgE and impaired cellular immunity. Not only the clinical appearance but also the hallmark immunological characteristics of SS often share striking similarities with acute flares of atopic dermatitis (AD), a common benign chronic inflammatory skin disease. Given the overlap of several immunological features, the application of similar or even identical therapeutic approaches in certain stages of both diseases may come into consideration. The aim of this review is to compare currently accepted immunological aspects and possible therapeutic targets in AD and SS.

Activation-dependent mitochondrial translocation of Foxp3 in human hepatocytes

Foxp3 is considered to be the master regulator for the development and function of regulatory T cells (Treg). Recently Foxp3, has been detected in extra lymphoid tissue, and in hepatocytes and has been associated with hepatocellular carcinoma (HCC), although its role has not been defined. Since it is expected that there is a relationship between protein localization, activity and cellular function, the aim of this study was to explore the subcellular localization of Foxp3 in resting and stimulated human hepatocytes. Foxp3 expression was measured by flow cytometry, subcellular fractioning, and immunofluorescence, and this data was used to track the shuttling of Foxp3 in different subcellular compartments in hepatocytes (HepG2 cell line), stimulated by using the PKC activators (PMA), core and preS1/2 antigen from hepatitis B virus (HBV). Our data shows that besides the nuclear location, mitochondrial translocation was detected after stimulation with PMA and at to a lesser extent, with preS1/2. In addition, Foxp3 is localizes at outer mitochondrial membrane. These results suggest a non-canonical role of Foxp3 in the mitochondrial compartment in human hepatocytes, and opens a new field about their role in liver damages during HBV infection.

Peripheral T-cell and NK cell lymphoproliferative disorders: cell of origin, clinical and pathological implications

T-cell lymphoproliferative disorders are a heterogeneous group of neoplasms with distinct clinical-biological properties. The normal cellular counterpart of these processes has been postulated based on functional and immunophenotypic analyses. However, T lymphocytes have been proven to be remarkably capable of modulating their properties, adapting their function in relationship with multiple stimuli and to the microenvironment. This impressive plasticity is determined by the equilibrium among a pool of transcription factors and by DNA chromatin regulators. It is now proven that the acquisition of specific genomic defects leads to the enforcement/activation of distinct pathways, which ultimately alter the preferential activation of defined regulators, forcing the neoplastic cells to acquire features and phenotypes distant from their original fate. Thus, dissecting the landscape of the genetic defects and their functional consequences in T-cell neoplasms is critical not only to pinpoint the origin of these tumors but also to define innovative mechanisms to re-adjust an unbalanced state to which the tumor cells have become addicted and make them vulnerable to therapies and targetable by the immune system. In our review, we briefly describe the pathological and clinical aspects of the T-cell lymphoma subtypes as well as NK-cell lymphomas and then focus on the current understanding of their pathogenesis and the implications on diagnosis and treatment.

Histopathological and immunophenotypical criteria for the diagnosis of Sézary syndrome in differentiation from other erythrodermic skin diseases: a European Organisation for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Task Force Study of 97 cases

BACKGROUND

Patients with erythrodermic disease are a diagnostic challenge regarding the clinical and histological differential diagnosis.

OBJECTIVES

To evaluate histopathological and immunohistochemical diagnostic markers for Sézary syndrome.

METHODS

Ninety-seven erythrodermic cases [Sézary syndrome (SS), n = 57; erythrodermic inflammatory dermatoses (EIDs), n = 40] were collected by the EORTC Cutaneous Lymphoma Task Force histopathology group. Evaluation criteria were (i) epidermal and dermal changes; (ii) morphology of the infiltrate; (iii) immunohistochemical analysis of marker loss (CD2, CD3, CD4, CD5 and CD7); (iv) bystander infiltrate by staining for CD8, FOXP3 and CD25; and (v) expression of Ki-67, CD30, PD-1 and MUM-1.

RESULTS

The workshop panel made a correct diagnosis of SS in 51% of cases (cutaneous T-cell lymphoma 81%) and of EID in 80% without clinical or laboratory data. Histology revealed a significantly increased degree of epidermotropism (P < 0.001) and more intraepidermal atypical lymphocytes (P = 0.0014) in SS biopsies compared with EID. Pautrier microabscesses were seen only in SS (23%) and not in EID (P = 0.0012). SS showed significantly more dermal cerebriform and blastic lymphocytes than EID. Immunohistochemistry revealed a significant loss of CD7 expression (< 50%) in 33 of 51 (65%) cases of SS compared with two of 35 (6%) EID (P < 0.001). The lymphocytic infiltrate in SS skin samples was found significantly to express PD-1 (P = 0.0053), MUM-1 (P = 0.0017) and Ki-67 (P < 0.001), and showed less infiltration of CD8(+) lymphocytes (P < 0.001). A multivariate analysis identified CD7 loss, increased numbers of small cerebriform lymphocytes, low numbers of CD8(+) lymphocytes and increased proliferation (Ki-67(+) lymphocytes) as the strongest indicators for the diagnosis of SS.

CONCLUSIONS

A number of different histological and immunophenotypical criteria are required to differentiate between SS and EIDs.

Malignant TOXication of T cells

In this issue of Blood, Huang et al show that aberrant expression of TOX plays a central role in malignant survival, proliferation, and tumor formation in cutaneous T-cell lymphoma (CTCL).

Altered balance between self-reactive T helper (Th)17 cells and Th10 cells and between full-length forkhead box protein 3 (FoxP3) and FoxP3 splice variants in Hashimoto's thyroiditis

T helper type 17 (Th17) cells play a pathogenic role in autoimmune disease, while interleukin (IL)-10-producing Th10 cells serve a protective role. The balance between the two subsets is regulated by the local cytokine milieu and by the relative expression of intact forkhead box protein 3 (FoxP3) compared to FoxP3Δ2, missing exon 2. Th17 and Th10 cell differentiation has usually been studied using polyclonal stimuli, and little is known about the ability of physiologically relevant self-antigens to induce Th17 or Th10 cell differentiation in autoimmune thyroid disease. We subjected mononuclear cells from healthy donors and patients with Hashimoto's thyroiditis (HT) or Graves' disease (GD) to polyclonal stimulation, or stimulation with human thyroglobulin (TG), human thyroid peroxidase (TPO), or Esherichia coli lipopolysaccharide (LPS). TPO and LPS induced increased differentiation of naive CD4(+) CD45RA(+) CD45R0(-) T cells from HT patients into Th17 cells. Th10 cell proportions were decreased in HT after polyclonal stimulation, but were comparable to those of healthy donors after antigen-specific stimulation. Taken together, our data show that an increased Th17 : Th10 ratio was found in HT patients after stimulation with thyroid-specific self-antigens. We also observed an elevated baseline production of IL-6 and transforming growth factor (TGF)-β1 and of mRNA encoding FoxP3Δ2 rather than intact FoxP3. This may contribute to the skewing towards Th17 cell responses in HT.

The effect of extracorporeal photopheresis alone or in combination therapy on circulating CD4(+) Foxp3(+) CD25(-) T cells in patients with leukemic cutaneous T-cell lymphoma

PURPOSE

Extracorporeal photopheresis (ECP) alone or in combination therapy is effective for treatment of leukemic cutaneous T-cell lymphoma (L-CTCL), but its mechanism(s) of action remain unclear. This study was designed to investigate the effect of ECP on regulatory T cells and CD8(+) T cells in L-CTCL patients.

EXPERIMENTAL DESIGN

Peripheral blood from 18 L-CTCL patients at baseline, Day 2, 1 month, 3 month, and 6 month post-ECP therapy was analyzed by flow cytometry for CD4(+) CD25(+/high) , CD4(+) Foxp3(+) CD25(+/-) , CD3(+) CD8(+) , CD3(+) CD8(+) CD69(+) , and CD3(+) CD8(+) IFN-γ(+) T cells. Clinical responses were assessed and correlated with changes in these T-cell subsets.

RESULTS

Twelve of 18 patients achieved clinical responses. The average baseline number of CD4(+) CD25(+/high) T cells of PBMCs in L-CTCL patients was normal (2.2%), but increased at 6-month post-therapy (4.3%, P < 0.01). The average baseline number of CD4(+) Foxp3(+) T cells out of CD4(+) T cells in nine evaluable patients was high (66.8 ± 13.7%), mostly CD25 negative. The levels of CD4(+) Foxp3(+) T cells in responders were higher (n = 6, 93.1 ± 5.7%) than nonresponders (n = 3, 14.2 ± 16.0%, P < 0.01), and they declined in parallel with malignant T cells. The numbers of CD3(+) CD8(+) CD69(+) and CD3(+) CD8(+) IFN-γ(+) T cells increased at 3-month post-therapy in five of six patients studied.

CONCLUSIONS

Extracorporeal photopheresis alone or in combination therapy might be effective in L-CTCL patients whose malignant T cells have a CD4(+) Foxp3(+) CD25(-) phenotype.

Bortezomib inhibits expression of TGF-β1, IL-10, and CXCR4, resulting in decreased survival and migration of cutaneous T cell lymphoma cells

Increased expression of the immunosuppressive cytokines, TGF-β1 and IL-10, is a hallmark of the advanced stages of cutaneous T cell lymphoma (CTCL), where it has been associated with suppressed immunity, increased susceptibility to infections, and diminished antitumor responses. Yet, little is known about the transcriptional regulation of TGF-β1 and IL-10 in CTCL, and about their function in regulating the CTCL cell responses. In this article, we show that TGF-β1 and IL-10 expression in CTCL cells is regulated by NF-κB and suppressed by bortezomib (BZ), which has shown promising results in the treatment of CTCL. However, although the TGF-β1 expression is IκBα dependent and is regulated by the canonical pathway, the IL-10 expression is IκBα independent, and its inhibition by BZ is associated with increased promoter recruitment of p52 that characterizes the noncanonical pathway. TGF-β1 suppression decreases CTCL cell viability and increases apoptosis, and adding exogenous TGF-β1 increases viability of BZ-treated CTCL cells, indicating TGF-β1 prosurvival function in CTCL cells. In addition, TGF-β1 suppression increases expression of the proinflammatory cytokines IL-8 and IL-17 in CTCL cells, suggesting that TGF-β1 also regulates the IL-8 and IL-17 expression. Importantly, our results demonstrate that BZ inhibits expression of the chemokine receptor CXCR4 in CTCL cells, resulting in their decreased migration, and that the CTCL cell migration is mediated by TGF-β1. These findings provide the first insights into the BZ-regulated TGF-β1 and IL-10 expression in CTCL cells, and indicate that TGF-β1 has a key role in regulating CTCL survival, inflammatory gene expression, and migration.

Blood flow cytometry in Sézary syndrome: new insights on prognostic relevance and immunophenotypic changes during follow-up

OBJECTIVES

Sézary syndrome (SS) is characterized by erythroderma, generalized lymphadenopathy, and the presence of circulating atypical lymphocytes, which are difficult to identify by morphologic data.

METHODS

We revised our series of 107 patients in an attempt to better define the phenotypic aberrancies in blood at diagnosis and the immunophenotypic stability over time detected by flow cytometry. Polymerase chain reaction assay was also used to study CD26/dipeptidyl peptidase IV (DPPIV) gene methylation.

RESULTS

The most common aberrancies were represented by the lack of CD26 (96/107) or CD38 (101/107) expression and the presence of a "dim" CD3, CD4, or CD2 population. There was a high variability in CD7 expression. In total, 31% of the patients had phenotypical heterogeneity in CD26 and CD7 expression at diagnosis. The phenotype was stable over time in 73 of 95 patients with available follow-up data, while 22 of 95 patients developed changes in CD26, CD7, or CD2 expression. CD4+CD26- SS showed hypermethylation of the CpG islands for the promoter region of CD26/DPPIV. Multivariate analysis showed that CD26 expression is a favorable prognostic factor (hazard ratio, 2.94; P = .045).

CONCLUSIONS

We confirm the relevance of CD26 negativity in SS diagnosis and monitoring. Nevertheless, the presence of rare CD26+ cases suggests that a multiparameter flow cytometry approach should be used. Changes in methylation profile could account for phenotypical heterogeneity.

Dissecting the role of the FOXP3 gene in the joint genetic susceptibility to autoimmune thyroiditis and diabetes: a genetic and functional analysis

We have previously shown that a (TC)n microsatellite in intron 5 of the Forkhead Box Protein 3 (FOXP3) gene was associated with a variant of the autoimmune polyglandular syndrome type 3 (APS3v), that is defined as the co-occurrence of type 1 diabetes (T1D) and autoimmune thyroiditis (AITD). Allele 10, containing 25 repeats of the microsatellite (long repeats), is preferentially transmitted to offspring with APS3v, while allele 2, containing 14 repeats of the microsatellite (short repeats), is protective. We hypothesized that the long repeats of the intron 5 microsatellite decrease FOXP3 splicing and function, thereby reducing regulatory T cell activity and promoting the development of APS3v. We cloned genomic DNA from two males hemizygous for the long and short repeats of the microsatellite on their X-chromosomes and transfected them into human embryonic kidney 293 (HEK 293) cells to perform direct splicing analysis. We identified a novel splice variant of FOXP3 lacking exon 6, and showed that it is expressed in human thymus and lymph node. However, the length of the repeats in the microsatellite did not significantly influence the expression of this FOXP3 splice variant in vitro. Interestingly, this splice variant was expressed in human regulatory T cells, suggesting that it may play a role in their function. In conclusion, we identified a novel splice variant FOXP3Δ6. The role of its expression in regulatory T cells in the development of autoimmunity remains to be determined.

FoxP3-Positive T-Regulatory Cells in Lymph Nodes with Mycosis Fungoides and Sézary Syndrome

Mycosis fungoides and Sézary syndrome are indolent cutaneous T-cell lymphomas, with skin-associated peripheral lymph nodes being the most frequent extracutaneous site of involvement. Acquisition of functional properties of regulatory T-cells by malignant T-cells in advanced disease may contribute to immunosuppression. Whereas previous studies examining FoxP3 protein expression in mycosis fungoides and Sézary syndrome have focused on skin specimens, little data are available on lymph nodes from patients with these conditions. In this study we examined FoxP3+ regulatory T-cells in lymph nodes from 26 patients with mycosis fungoides and Sézary syndrome and correlated the findings with clinical data, molecular assays for T-cell clonality, and flow cytometry. Except for one case of Sézary syndrome in which malignant T-cells expressed FoxP3 protein, a significantly lower number of FoxP3-expressing cells occurred in lymph nodes that were clearly involved with lymphoma as compared to uninvolved nodes. Cox proportional hazards model showed that lymph node rating and histological evidence of transformation, but not number of FoxP3+ cells, were factors significantly associated with adverse prognosis. We speculate that modulation of FoxP3+ cells in lymph nodes involved with lymphoma might play a role in disease progression. Attainment of a regulatory T-cell phenotype by a subset of lymphoma cells might signal a poor prognosis.

Staphylococcal enterotoxins stimulate lymphoma-associated immune dysregulation

Patients with cutaneous T-cell lymphoma (CTCL) are frequently colonized with Staphylococcus aureus (SA). Eradication of SA is, importantly, associated with significant clinical improvement, suggesting that SA promotes the disease activity, but the underlying mechanisms remain poorly characterized. Here, we show that SA isolates from involved skin express staphylococcal enterotoxins (SEs) that induce crosstalk between malignant and benign T cells leading to Stat3-mediated interleukin-10 (IL-10) production by the malignant T cells. The SEs did not stimulate the malignant T cells directly. Instead, SEs triggered a cascade of events involving cell-cell and asymmetric cytokine interactions between malignant and benign T cells, which stimulated the malignant T cells to express high levels of IL-10. Much evidence supports that malignant activation of the Stat3/IL-10 axis plays a key role in driving the immune dysregulation and severe immunodeficiency that characteristically develops in CTCL patients. The present findings thereby establish a novel link between SEs and immune dysregulation in CTCL, strengthening the rationale for antibiotic treatment of colonized patients with severe or progressive disease.

IL-15 and IL-17F are differentially regulated and expressed in mycosis fungoides (MF)

Skin lesions from mycosis fungoides (MF) patients display an increased expression of interleukin-15 (IL-15), IL-17F, and other cytokines implicated in inflammation and malignant cell proliferation in cutaneous T-cell lymphoma (CTCL). In the leukemic variant of CTCL, Sézary syndrome (SS), IL-2 and IL-15 trigger activation of the Jak-3/STAT3 pathway and transcription of IL17A gene, whereas it is unknown what causes IL-15 expression, Jak3/STAT3 activation, and production of IL-17F in MF. Here, we studied the expression and regulation of IL-15 and its relation to IL-17F in MF cell lines and skin lesions from 60 MF patients. We show that: (1) the spontaneous IL-15 mRNA expression is resistant to Jak3 and STAT3 inhibitors at concentrations that profoundly inhibit STAT3 activation and IL-17F mRNA expression; (2) anti-IL-15 antibody blocks STAT3 activation induced by exogenous IL-15 in non-malignant MF T cells, whereas the spontaneous STAT3 activation and IL-17F expression in malignant T cells is not inhibited; (3) patients display heterogeneous IL-15/IL-17F mRNA expression patterns in skin lesions; and (4) IL-15 expression (in contrast to IL-17F) is not associated with progressive disease. Taken together, these findings indicate that IL-15 and IL-17F are differentially regulated and expressed in MF. We propose that IL-15 and IL-17F are markers for different inflammatory environments and play distinct roles in the development and progression of MF.

Expression of miR-155 and miR-126 in situ in cutaneous T-cell lymphoma

Recently, miR-155 has been implicated in cutaneous T-cell lymphoma (CTCL). Thus, elevated levels of miR-155 were observed in skin lesions from CTCL patients as judged from qPCR and micro-array analysis and aberrant, high miR-155 expression was associated with severe disease. Moreover, miR-155 promoted proliferation of malignant T cells in vitro. Little is, however, known about which cell types express miR-155 in vivo in CTCL skin lesions. Here, we study miR-155 expression using in situ hybridization (ISH) with a miR-155 probe, a negative control (scrambled), and a miR-126 probe as a positive control in nine patients with mycosis fungoides, the most frequent subtype of CTCL. We provide evidence that both malignant and non-malignant T cells stain weakly to moderately positive with the miR-155 probe, but generally negative with the miR-126 and negative control probes. Reversely, endothelial cells stain positive for miR-126 and negative for miR-155 and the control probe. Solitary T cells with a malignant morphology display brighter staining with the miR-155 probe. Taken together, our findings suggest that both malignant and non-malignant T cells express miR-155 in situ in CTCL. Moreover, they indicate heterogeneity in miR-155 expression among malignant T cells.

Wasik M, B. Koralov S, Geisler C, Kilian M, Iversen L, Woetmann A, Odum N. Bacterial toxins fuel disease progression in cutaneous T-cell lymphoma

In patients with cutaneous T-cell lymphoma (CTCL) bacterial infections constitute a major clinical problem caused by compromised skin barrier and a progressive immunodeficiency. Indeed, the majority of patients with advanced disease die from infections with bacteria, e.g., Staphylococcus aureus. Bacterial toxins such as staphylococcal enterotoxins (SE) have long been suspected to be involved in the pathogenesis in CTCL. Here, we review links between bacterial infections and CTCL with focus on earlier studies addressing a direct role of SE on malignant T cells and recent data indicating novel indirect mechanisms involving SE- and cytokine-driven cross-talk between malignant- and non-malignant T cells.

Functional characterization of Foxp3-specific spontaneous immune responses

Tumor-infiltrating CD4+CD25+ regulatory T cells (Tregs) are associated with an impaired prognosis in several cancers. The transcription factor forkhead box P3 (Foxp3) is generally expressed in Tregs. Here, we identify and characterize spontaneous cytotoxic immune responses to Foxp3-expressing cells in peripheral blood of healthy volunteers and cancer patients. These immune responses were directed against a HLA-A2-restricted peptide epitope derived from Foxp3. Foxp3-reactive T cells were characterized as cytotoxic CD8+ T cells. These cells recognized dendritic cells incubated with recombinant Foxp3 protein indicating that this protein was indeed internalized, processed and cross-presented in the context of HLA-A2. More importantly, however, Foxp3-specific T cells were able to specifically recognize Tregs. Similarly, Foxp3+ malignant T cells established from a Cutaneous T-cell lymphomas (CTCL) patient were readily killed by the Foxp3-specific cytotoxic T lymphocytes. The spontaneous presence of Foxp3-specific cytotoxic T-cell responses suggest a general role of such T cells in the complex network of immune regulation as such responses may eliminate Tregs, that is, suppression of the suppressors. Consequently, induction of Foxp3-specific cytotoxic T-cell responses appears as an attractive tool to boost spontaneous or therapeutically provoked immune responses, for example, for the therapy of cancer.

Elucidating the role of interleukin-17F in cutaneous T-cell lymphoma

Inappropriately regulated expression of interleukin (IL)-17A is associated with the development of inflammatory diseases and cancer. However, little is known about the role of other IL-17 family members in carcinogenesis. Here, we show that a set of malignant T-cell lines established from patients with cutaneous T-cell lymphoma (CTCL) spontaneously secrete IL-17F and that inhibitors of Janus kinases and Signal transducer and activator of transcription 3 are able to block that secretion. Other malignant T-cell lines produce IL-17A but not IL-17F. Upon activation, however, some of the malignant T-cell lines are able to coexpress IL-17A and IL-17F, leading to formation of IL-17A/F heterodimers. Clinically, we demonstrate that IL-17F messenger RNA expression is significantly increased in CTCL skin lesions compared with healthy donors and patients with chronic dermatitis. IL-17A expression is also increased and a significant number of patients express high levels of both IL-17A and IL-17F. Concomitantly, we observed that the expression of the IL-17 receptor is significantly increased in CTCL skin lesions compared with control subjects. Importantly, analysis of a historic cohort of 60 CTCL patients indicates that IL-17F expression is associated with progressive disease. These findings implicate IL-17F in the pathogenesis of CTCL and suggest that IL-17 cytokines and their receptors may serve as therapeutic targets.

TH2 cytokines from malignant cells suppress TH1 responses and enforce a global TH2 bias in leukemic cutaneous T-cell lymphoma

PURPOSE

In leukemic cutaneous T-cell lymphoma (L-CTCL), malignant T cells accumulate in the blood and give rise to widespread skin inflammation. Patients have intense pruritus, increased immunoglobulin E (IgE), and decreased T-helper (TH)-1 responses, and most die from infection. Depleting malignant T cells while preserving normal immunity is a clinical challenge. L-CTCL has been variably described as a malignancy of regulatory, TH2 and TH17 cells.

EXPERIMENTAL DESIGN

We analyzed phenotype and cytokine production in malignant and benign L-CTCL T cells, characterized the effects of malignant T cells on healthy T cells, and studied the immunomodulatory effects of treatment modalities in patients with L-CTCL.

RESULTS

Twelve out of 12 patients with L-CTCL overproduced TH2 cytokines. Remaining benign T cells were also strongly TH2 biased, suggesting a global TH2 skewing of the T-cell repertoire. Culture of benign T cells away from the malignant clone reduced TH2 and enhanced TH1 responses, but separate culture had no effect on malignant T cells. Coculture of healthy T cells with L-CTCL T cells reduced IFNγ production and neutralizing antibodies to interleukin (IL)-4 and IL-13 restored TH1 responses. In patients, enhanced TH1 responses were observed following a variety of treatment modalities that reduced malignant T-cell burden.

CONCLUSIONS

A global TH2 bias exists in both benign and malignant T cells in L-CTCL and may underlie the infectious susceptibility of patients. TH2 cytokines from malignant cells strongly inhibited TH1 responses. Our results suggest that therapies that inhibit TH2 cytokine activity, by virtue of their ability to improve TH1 responses, may have the potential to enhance both anticancer and antipathogen responses.

FOXP3: genetic and epigenetic implications for autoimmunity

FOXP3 plays an essential role in the maintenance of self-tolerance and, thus, in preventing autoimmune diseases. Inactivating mutations of FOXP3 cause immunodysregulation, polyendocrinopathy, and enteropathy, X-linked syndrome. FOXP3-expressing regulatory T cells attenuate autoimmunity as well as immunity against cancer and infection. More recent studies demonstrated that FOXP3 is an epithelial cell-intrinsic tumor suppressor for breast, prostate, ovary and other cancers. Corresponding to its broad function, FOXP3 regulates a broad spectrum of target genes. While it is now well established that FOXP3 binds to and regulates thousands of target genes in mouse and human genomes, the fundamental mechanisms of its broad impact on gene expression remain to be established. FOXP3 is known to both activate and repress target genes by epigenetically regulating histone modifications of target promoters. In this review, we first focus on germline mutations found in the FOXP3 gene among IPEX patients, then outline possible molecular mechanisms by which FOXP3 epigenetically regulates its targets. Finally, we discuss clinical implications of the function of FOXP3 as an epigenetic modifier. Accumulating results reveal an intriguing functional convergence between FOXP3 and inhibitors of histone deacetylases. The essential epigenetic function of FOXP3 provides a foundation for experimental therapies against autoimmune diseases.

Vascular endothelial growth factor receptor-3 expression in mycosis fungoides

Here, we have studied vascular endothelial growth factor receptor-3 (VEGFR-3) expression in mycosis fungoides (MF), the most common type of cutaneous T-cell lymphoma (CTCL). Immunohistochemistry revealed that in two-thirds of 34 patients, VEGFR-3 was expressed in situ by both tumor and stromal cells irrespective of the disease stage. The natural VEGFR-3 ligand, VEGF-C, partially protected malignant T-cell lines from growth inhibition by the histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA). Whereas the malignant T cells did not produce VEGF-C in vitro, its expression was induced during tumor formation in vivo in a xenograft mouse model of MF. In conclusion, malignant and stromal cells express high levels of VEGFR-3 in all stages of MF. Moreover, malignant T cells trigger enhanced VEGF-C expression in fibroblasts, suggesting that cross-talk between tumor and stromal cells plays a role in lymphangiogenesis and possibly disease progression.

Differential effects of decoy receptor- and antibody-mediated tumour necrosis factor blockage on FoxP3 expression in responsive arthritis patients

Our aim was to clarify if anti-tumour necrosis factor (TNF) drugs have effect on expression of three splice forms of FoxP3 mRNA in blood CD4+ T cells from rheumatoid arthritis (RA) patients compared with healthy controls. Forty-five rheumatoid arthritis patients treated with anti-TNF therapy were investigated in a 12-week prospective cohort study. FoxP3 isoforms, CD25 and CTLA-4 mRNA in blood CD4+ T cells were measured with quantitative real-time PCR. Patients benefitting from the treatment, based on changes in DAS28 scores, revealed a significant decrease in expression of full-length FoxP3 following 12 weeks treatment with TNF receptor 2 fusion protein (Etanercept), but not following treatment with anti-TNF antibodies (Adalimumab or Infliximab). A partial normalization of the CTLA-4/FoxP3fl ratio and a correlation between clinical improvement and change in FoxP3 mRNA expression were also seen in Etanercept responders. These changes were not observed in responsive patients treated with the antibody therapies. Our data suggest that TNF decoy receptor and anti-TNF antibodies differ in their effect on FoxP3 expression in responsive patients. As Etanercept binds both TNF-α and Lymphotoxin-α (LT-α), whereas the antibodies only target TNF-α, LT-α may regulate FoxP3 expression in a subset of RA patients. Our findings support the view that anti-TNF treatment is mainly symptomatic.