Gain of CD26 expression on the malignant T-cells in relapsed erythrodermic leukemic mycosis fungoides.

Loss of CD26 surface expression on the circulating malignant T-cell is the most widely accepted diagnostic marker in patients with leukemic cutaneous T-cell lymphoma (CTCL). CTCL cases with reemergence of CD7 and/or CD26 surface expression are unusual and of uncertain prognosis. We report the case of an erythrodermic leukemic mycosis fungoides patient who had achieved temporary remission after several months on multimodality immunotherapy and extracorporeal photopheresis, but who relapsed with aggressive disease phenotypically characterized by CD4+ T-cells with high CD26 expression. Polymerase chain reaction studies and high-throughput sequencing analyses from peripheral blood mononuclear cells at presentation and relapse consistently showed an identical clonal T-cell receptor suggesting evolution of her original malignant clone which lacked CD26 expression. Interestingly, quantitative expression of the sialomucin, CD164, mirrored her clinical picture, thus favoring its reliability as a novel biomarker in CTCL.

Melanoma Cell Galectin-1 Ligands Functionally Correlate with Malignant Potential.

Galectin-1 (Gal-1)-binding to Gal-1 ligands on immune and endothelial cells can influence melanoma development through dampening antitumor immune responses and promoting angiogenesis. However, whether Gal-1 ligands are functionally expressed on melanoma cells to help control intrinsic malignant features remains poorly understood. Here, we analyzed expression, identity, and function of Gal-1 ligands in melanoma progression. Immunofluorescent analysis of benign and malignant human melanocytic neoplasms revealed that Gal-1 ligands were abundant in severely dysplastic nevi, as well as in primary and metastatic melanomas. Biochemical assessments indicated that melanoma cell adhesion molecule (MCAM) was a major Gal-1 ligand on melanoma cells that was largely dependent on its N-glycans. Other melanoma cell Gal-1 ligand activity conferred by O-glycans was negatively regulated by α2,6 sialyltransferase ST6GalNAc2. In Gal-1-deficient mice, MCAM-silenced (MCAM(KD)) or ST6GalNAc2-overexpressing (ST6(O/E)) melanoma cells exhibited slower growth rates, underscoring a key role for melanoma cell Gal-1 ligands and host Gal-1 in melanoma growth. Further analysis of MCAM(KD) or ST6(O/E) melanoma cells in cell migration assays indicated that Gal-1 ligand-dependent melanoma cell migration was severely inhibited. These findings provide a refined perspective on Gal-1/melanoma cell Gal-1 ligand interactions as contributors to melanoma malignancy.

Improved pruritus correlates with lower levels of IL-31 in CTCL patients under different therapeutic modalities.

Pruritus is one of the cardinal symptoms found in patients with leukemic cutaneous T cell lymphoma (CTCL). The nature of the pruritus experienced by CTCL patients is complex, involving different pathways and cell mediators, thus making it poorly responsive to conventional anti-itch therapies. Recent reports highlight the role of interleukin 31 (IL-31) as a novel cytokine involved in the pathogenesis of pruritus in atopic dermatitis and CTCL. Here we provide both in vivo and in vitro evidence suggesting that histone deacetylase (HDAC) inhibitors may mitigate itch through lowering of levels of IL-31-expressing T cells. Furthermore, we demonstrate that chemokine receptor type-4 (CCR4)-bearing T cells are a main source of IL-31 in CTCL, and that neutralizing the IL-31 pathway through targeting of the CCR4-expressing T cells may represent a promising therapeutic strategy for symptomatic relief in CTCL.

Galectins and their ligands: negative regulators of anti-tumor immunity.

Cytotoxic CD8(+) T cells are major players of anti-tumor immune responses, as their functional activity can limit tumor growth and progression. Data show that cytotoxic T cells efficiently control the proliferation of tumor cells through major histocompatibility complex class I-mediated mechanisms; nevertheless, the presence of tumor-infiltrating CD8(+) T cells in lesional tissue does not always correlate with better prognosis and increased survival of cancer patients. Similarly, adoptive transfer of tumor-specific cytotoxic T cells has only shown marginal improvement in life spans of patients with metastatic disease. In this report, we discuss experimental evidence showing that expression of tumor-derived galectins, galectin (Gal)-1, Gal-3 and Gal-9, and concomitant presence of their ligands on the surface of anti-tumor immunocytes directly compromise anti-tumor CD8(+) T cell immune responses and, perhaps, undermine the promise of adoptive CD8(+) T cell immunotherapy. Furthermore, we describe novel strategies designed to counteract Gal-1-, Gal-3- and Gal-9-mediated effects and highlight their targeting potential for creating more effective anti-tumor immune responses. We believe that Gal and their ligands represent an efficacious targeted molecular paradigm that warrants clinical evaluation.

Galectin-1 inhibits the viability, proliferation, and Th1 cytokine production of nonmalignant T cells in patients with leukemic cutaneous T-cell lymphoma.

Tumor-derived galectin-1 (Gal-1), a ß-galactoside-binding S-type lectin, has been shown to encourage T-cell death and promote T cell-mediated tumor immune escape. In this report, we show that patients with leukemic cutaneous T-cell lymphomas, known to have limited complexity of their T-cell repertoires, have a predominant T helper type-2 (Th2) cytokine profile and significantly elevated plasma levels of Gal-1 compared with healthy controls. Circulating clonal malignant T cells were a major source of Gal-1. The conditioned supernatant of cultured malignant T cells induced a ß-galactoside-dependent inhibition of normal T-cell proliferation and a Th2 skewing of cytokine production. These data implicate Gal-1 in development of the Th2 phenotype in patients with advanced-stage cutaneous T-cell lymphoma and highlight the Gal-1-Gal-1 ligand axis as a potential therapeutic target for enhancing antitumor immune responses.

Galectin-1 triggers an immunoregulatory signature in Th cells functionally defined by IL-10 expression.

Galectin-1 (Gal-1), a ß-galactoside-binding protein, can alter fate and effector function of Th cells; however, little is known about how Gal-1 induces Th cell differentiation. In this article, we show that both uncommitted and polarized Th cells bound by Gal-1 expressed an immunoregulatory signature defined by IL-10. IL-10 synthesis was stimulated by direct Gal-1 engagement to cell surface glycoproteins, principally CD45, on activated Th cells and enhanced by IL-21 expression through the c-Maf/aryl hydrocarbon receptor pathway, independent of APCs. Gal-1-induced IL-10(+) T cells efficiently suppressed T cell proliferation and T cell-mediated inflammation and promoted the establishment of cancer immune-privileged sites. Collectively, these findings show how Gal-1 functions as a major glycome determinant regulating Th cell development, inflammation, and tumor immunity.

Galectin-1 research in T cell immunity: past, present and future.

Galectin-1 (Gal-1) is one of 15 evolutionarily conserved ß-galactoside-binding proteins that display biologically-diverse activities in pathogenesis of inflammation and cancer. Gal-1 is variably expressed on immune cells and endothelial cells, though is commonly found and secreted at high levels in cancer cells. It induces apoptosis in effector T cells through homodimeric binding of N-acetyllactosamines on membrane glycoproteins (Gal-1 ligands). There is also compelling evidence in models of cancer and autoimmunity that recombinant Gal-1 (rGal-1) can potentiate immunoregulatory function of T cells. Here, we review Gal-1's structural and functional features, while analyzing potential drawbacks and technical difficulties inherent to rGal-1's nature. We also describe new Gal-1 preparations that exhibit dimeric stability and functional activity on T cells, providing renewed excitement for studying Gal-1 efficacy and/or use as anti-inflammatory therapeutics. We lastly summarize strategies targeting the Gal-1-Gal-1 ligand axis to circumvent Gal-1-driven immune escape in cancer and boost anti-tumor immunity.

Metabolic inhibition of galectin-1-binding carbohydrates accentuates antitumor immunity.

Galectin-1 (Gal-1) has been shown to play a major role in tumor immune escape by inducing apoptosis of effector leukocytes and correlating with tumor aggressiveness and disease progression. Thus, targeting the Gal-1/Gal-1 ligand axis represents a promising cancer therapeutic approach. Here, to test the Gal-1-mediated tumor immune evasion hypothesis and demonstrate the importance of Gal-1-binding N-acetyllactosamines in controlling the fate and function of antitumor immune cells, we treated melanoma- or lymphoma-bearing mice with peracetylated 4-fluoro-glucosamine (4-F-GlcNAc), a metabolic inhibitor of N-acetyllactosamine biosynthesis, and analyzed tumor growth and immune profiles. We found that 4-F-GlcNAc spared Gal-1-mediated apoptosis of T cells and natural killer (NK) cells by decreasing their expression of Gal-1-binding determinants. 4-F-GlcNAc enhanced tumor lymphocytic infiltration and promoted elevations in tumor-specific cytotoxic T cells and IFN-γ levels, while lowering IL-10 production. Collectively, our data suggest that metabolic lowering of Gal-1-binding N-acetyllactosamines may attenuate tumor growth by boosting antitumor immune cell levels, representing a promising approach for cancer immunotherapy.

Peracetylated 4-fluoro-glucosamine reduces the content and repertoire of N- and O-glycans without direct incorporation.

Prior studies have shown that treatment with the peracetylated 4-fluorinated analog of glucosamine (4-F-GlcNAc) elicits anti-skin inflammatory activity by ablating N-acetyllactosamine (LacNAc), sialyl Lewis X (sLe(X)), and related lectin ligands on effector leukocytes. Based on anti-sLe(X) antibody and lectin probing experiments on 4-F-GlcNAc-treated leukocytes, it was hypothesized that 4-F-GlcNAc inhibited sLe(X) formation by incorporating into LacNAc and blocking the addition of galactose or fucose at the carbon 4-position of 4-F-GlcNAc. To test this hypothesis, we determined whether 4-F-GlcNAc is directly incorporated into N- and O-glycans released from 4-F-GlcNAc-treated human sLe(X) (+) T cells and leukemic KG1a cells. At concentrations that abrogated galectin-1 (Gal-1) ligand and E-selectin ligand expression and related LacNAc and sLe(X) structures, MALDI-TOF and MALDI-TOF/TOF mass spectrometry analyses showed that 4-F-GlcNAc 1) reduced content and structural diversity of tri- and tetra-antennary N-glycans and of O-glycans, 2) increased biantennary N-glycans, and 3) reduced LacNAc and sLe(X) on N-glycans and on core 2 O-glycans. Moreover, MALDI-TOF MS did not reveal any m/z ratios relating to the presence of fluorine atoms, indicating that 4-F-GlcNAc did not incorporate into glycans. Further analysis showed that 4-F-GlcNAc treatment had minimal effect on expression of 1200 glycome-related genes and did not alter the activity of LacNAc-synthesizing enzymes. However, 4-F-GlcNAc dramatically reduced intracellular levels of uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc), a key precursor of LacNAc synthesis. These data show that Gal-1 and E-selectin ligand reduction by 4-F-GlcNAc is not caused by direct 4-F-GlcNAc glycan incorporation and consequent chain termination but rather by interference with UDP-GlcNAc synthesis.

Human Polyomavirus-Associated Cerebral Disorders in the Post-HAART Era.

Human polyomavirus JC is the causative agent of a deadly form of sudden onset dementia, progressive multifocal leukocoencephalopathy (PML). PML is highly prevalent in immunodeficient populations, specially those undergoing chemotherapy, immunosuppressive treatments for autoimmune conditions, and HIV-1/AIDS patients. In fact, before the highly active antiretroviral therapy (HAART) regimens became available, PML was a leading cause of death in HIV-1 seropositive individuals. However, patients under HAART show increased survival times with better prognoses. In this report we described the main differences between PML before and after the HAART era; highlighting the new patterns of presentation, the neurotropism of other human polyomaviruses, and the increased prevalence of immune reconstitution inflammatory syndrome (IRIS), as a complication of PML in patients under HAART. Lastly, we propose a revised classification of human poliomavirus-associated cerebral disorders that may reflect more accurately what clinicians encounter in their everyday practice.

New insights into HIV-1-primary skin disorders.

Since the first reports of AIDS, skin involvement has become a burdensome stigma for seropositive patients and a challenging task for dermatologist and infectious disease specialists due to the severe and recalcitrant nature of the conditions. Dermatologic manifestations in AIDS patients act as markers of disease progression, a fact that enhances the importance of understanding their pathogenesis.Broadly, cutaneous disorders associated with HIV type-1 infection can be classified as primary and secondary. While the pathogenesis of secondary complications, such as opportunistic infections and skin tumours, is directly correlated with a decline in the CD4+ T cell count, the origin of the certain manifestations primarily associated with the retroviral infection itself still remains under investigation.The focus of this review is to highlight the immunological phenomena that occur in the skin of HIV-1-seropositive patients, which ultimately lead to skin disorders, such as seborrhoeic dermatitis, atopic dermatitis, psoriasis and eosinophilic folliculitis. Furthermore, we compile the latest data on how shifts in the cytokines milieu, impairments of the innate immune compartment, reactions to xenobiotics and autoimmunity are causative agents in HIV-1-driven skin diseases. Additionally, we provide a thorough analysis of the small animal models currently used to study HIV-1-associated skin complications, centering on transgenic rodent models, which unfortunately, have not been able to fully unveil the role of HIV-1 genes in the pathogenesis of their primarily associated dermatological manifestations.

Development of a nascent galectin-1 chimeric molecule for studying the role of leukocyte galectin-1 ligands and immune disease modulation.

Galectin-1 (Gal-1), a ß-galactoside-binding lectin, plays a profound role in modulating adaptive immune responses by altering the phenotype and fate of T cells. Experimental data showing recombinant Gal-1 (rGal-1) efficacy on T cell viability and cytokine production, nevertheless, is controversial due to the necessity of using stabilizing chemicals to help retain Gal-1 structure and function. To address this drawback, we developed a mouse Gal-1 human Ig chimera (Gal-1hFc) that did not need chemical stabilization for Gal-1 ligand recognition, apoptosis induction, and cytokine modulation in a variety of leukocyte models. At high concentrations, Gal-1hFc induced apoptosis in Gal-1 ligand(+) Th1 and Th17 cells, leukemic cells, and granulocytes from synovial fluids of patients with rheumatoid arthritis. Importantly, at low, more physiologic concentrations, Gal-1hFc retained its homodimeric form without losing functionality. Not only did Gal-1hFc-binding trigger IL-10 and Th2 cytokine expression in activated T cells, but members of the CD28 family and several other immunomodulatory molecules were upregulated. In a mouse model of contact hypersensitivity, we found that a non-Fc receptor-binding isoform of Gal-1hFc, Gal-1hFc2, alleviated T cell-dependent inflammation by increasing IL-4(+), IL-10(+), TGF-ß(+), and CD25(high)/FoxP3(+) T cells, and by decreasing IFN-γ(+) and IL-17(+) T cells. Moreover, in human skin-resident T cell cultures, Gal-1hFc diminished IL-17(+) T cells and increased IL-4(+) and IL-10(+) T cells. Gal-1hFc will not only be a useful new tool for investigating the role of Gal-1 ligands in leukocyte death and cytokine stimulation, but for studying how Gal-1-Gal-1 ligand binding shapes the intensity of immune responses.

Inflammatory papillomatous hyperplasia and epidermal necrosis in a transgenic rat for HIV-1.

BACKGROUND: Skin lesions commonly affect AIDS patients. The pathogenesis of certain dermatologic disorders primarily associated to HIV-1 is unclear, and better forms of therapy for these conditions need to be discovered. Transgenic animal models represent a novel approach for the study of these disorders and for the quest of more effective forms of treatment. OBJECTIVE: Characterize this HIV-1 transgenic rat as a model to study skin diseases related to HIV/AIDS. METHODS: A transgenic rat was developed, using an HIV-1 construct with deleted gag and pol genes. Morphological and genotypical evaluations were followed by cytokine profile characterization of the lesions. RESULTS: We report the characterization of a colony of HIV-1 transgenic rats that developed skin lesions in a frequency of 22.5%. Cutaneous expression of functional HIV-1 transgenes correlated precisely with the severity of the phenotype. In early stages, rats manifested localized areas of xerosis and dispersed papulosquamous lesions. These hyperplastic manifestations were observed in conjunction with an increased epidermal expression of tat protein and a Th1/Th2 profile of cytokines. As the lesions progressed, they formed inflammatory plaques that subsequently ulcerated. Histologically, these lesions displayed a profound lymphocytic infiltrate, epidermal necrosis, and a marked increase of both Th1 and Th2 derived cytokines. Moreover, the presence of circulating IgG antibodies against HIV-1 gp120 was detected. CONCLUSION: This animal model as other HIV-1 transgenic mice described in the past, is not able to fully explain the myriad of skin findings that can occur in HIV-infected humans; however, it represents a potential animal model system for the study of immune-mediated inflammatory skin diseases.

BK virus associated meningoencephalitis in an AIDS patient treated with HAART.

A severely immune-suppressed AIDS patient was suspected of suffering from BK virus (BKV) meningoencephalitis, after being studied for common causes of neurological complications of co-infectious origin. Polymerase chain reaction (PCR) and sequence analysis of cerebrospinal fluid and brain samples, confirmed the presence of BKV. His clinical condition improved along with the regression of brain lesions, after modifications on his antiretroviral regime. Five months after discharge, the patient was readmitted because of frequent headaches, and a marked inflammatory reaction was evidenced by a new magnetic resonance imaging (MRI). The symptoms paralleled a rising CD4+ lymphocyte count, and immune reconstitution syndrome was suspected. This is the first non-postmortem report of BKV meningoencephalitis in an AIDS patient, showing clinical and radiographic improvement solely under HAART.