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Pathogenesis of Neutropenia in large granular lymphocyte leukemia: immunophenotypic and molecular characterization of neutropenic patients
Get PDFLarge Granular Lymphocytes (LGLs) leukemia (LGLL) is a chronic lymphoproliferation of clonal cytotoxic LGLs, which can be divided in two different subsets, based on Cluster of Differentiation (CD)-3 expression: CD3- Natural Killer (NK) cells and CD3+/CD8+/CD4- or CD3+/CD8-/dim/CD4+ T-LGLs.
Leukemic LGLs are characterized by the up-regulation of several pro-survival signaling pathways. Among these, the most relevant is the JAK-STAT axis, whose constitutive activation is in part explained by somatic activating mutations in STAT3 and STAT5b.
Neutropenia is the most frequent clinical manifestation, but its pathogenesis is still unknown, although high levels of soluble Fas Ligand (sFasL) were detected in serum of LGLL patients and supposed to trigger neutrophil’s death.
This work aimed i) to describe the distinctive biological features of T-LGLs or NK cells of neutropenic LGLL patients; ii) to investigate the role of microRNAs in the regulation of sFasL expression in leukemic LGLs.
LGLs were purified by FACSAriaIII cell sorter from peripheral blood mononuclear cells (PBMCs) of untreated LGLL patients and their immunophenotype was evaluated by Flow Cytometry. The screening of STATs mutations was performed by Sanger sequencing. PBMCs of patients were cultured in vitro and STAT3 transcriptional activity were inhibited or stimulated with Stattic or IL-6, respectively. Transcriptional and protein expression levels were evaluated by Real Time-PCR, Western Blot (WB) assays and ELISA test.High throughput and single miRNA analysis were carried out on purified T-LGLs by using the TaqMan® Human microRNA Array and Assays, respectively. Transfection with miR-146b mimic was performed using the Amaxa Nucleofactor and the Ingenio Electroporation Solution.
We showed that leukemic T-LGLs of neutropenic patients were characterized by CD3+/CD8+/CD16+/CD56- phenotype, higher STAT3 activations, higher incidence of STAT3 mutations and higher levels of sFasL, compared to T-LGLs of non-neutropenic patients. We also demonstrated that FasL transcription was mediated by STAT3 activation in T-LGLL patients.
The characterization of neutropenic CLPD-NK patients, instead, showed that they are characterized by CD56-/dim/CD16high/CD57- cytotoxic NK cells expansion. However, we observed a heterogeneous level of STAT3 activation and a heterogeneous expression of FasL in this subset of patients.
To investigate whether STAT3 could play its pathogenetic role in T-LGLs through an altered expression of microRNAs, we studied miRNAs differentially expressed in patients characterized by neutropenia as compared to those with normal absolute neutrophil count (ANC). We showed that miR-146b expression, found down-regulated in neutropenic patients, was correlated with the ANC of T-LGLL patients.
To investigate miR-146b role in neutropenia development, we transfected purified T-LGLs with a miR-146b mimic. We showed that restoration of miR-146b led to a decrease of FasL mRNA, without changes in the FasL primary transcript as compared to control. However, FasL was not identified among the putative miR-146b target genes, suggesting that miR-146b could regulate FasL expression indirectly. Therefore, we checked for genes involved in mRNA stability and we found that the defective miR-146b expression lead to increased transcriptional levels of the mRNA stabilizer HuR, that is required for FasL expression in T-lymphocytes10. Consistently, by WB assays, we demonstrated that in T-LGLs of neutropenic patients HuR endogenous protein levels were higher than in T-LGLs of non-neutropenic ones. HuR-mediated FasL mRNA stabilization explained the increased FasL expression observed in neutropenic patients.
In this work we identify distinctive features of neutropenic LGLL patients, that could acquire relevance to correctly address the management of each patient, and we identify a miR-146b-FasL axis involved in neutropenia development in leukemic T-LGLs
T-cell clones of uncertain significance. When is the rogue clone dangerous?
Get PDF: T cell large granular lymphocyte clones that persist over time and that exhibit molecular and immunophenotypic features closely resembling those of T-cell Large Granular Lymphocyte Leukemia (T-LGLL) may be detectable in individuals who lack any clinical or laboratory features supporting a diagnosis of T-cell malignancy. This condition represents a potential precursor state termed T cell clones of uncertain significance (T-CUS). T-CUS represents the even more benign extreme of the wide spectrum of clonal T- large granular lymphocyte proliferations, emphasizing the need for an appropriate multiparametric diagnostic assessment that avoids misdiagnosis of T-cell neoplasia. This approach should overcome the numerical cut-offs as the sole criteria to differentiate the benign condition from the related malignancies. In particular, genomic aberrancies might prospectively identify individuals who are at risk of progression to full blown T-cell malignancy. We herein discuss the significance of these T cell clones in both healthy and disease states suggesting molecular assays for tracking early steps of disease
All that glitters is not LGL Leukemia
No full textLGL disorders are rare hematological neoplasias with remarkable phenotypic, genotypic and clinical heterogeneity. Despite these constraints, many achievements have been recently accomplished in understanding the aberrant pathways involved in the LGL leukemogenesis. In particular, compelling evidence implicates STAT signaling as a crucial player of the abnormal cell survival. As interest increases in mapping hematological malignancies by molecular genetics, the relevance of STAT gene mutations in LGL disorders has emerged thanks to their association with discrete clinical features. STAT3 and STAT5b mutations are recognized as the most common gain-of-function genetic lesions up to now identified in T-LGL leukemia (T-LGLL) and are actually regarded as the hallmark of this disorder, also contributing to further refine its subclassification. However, from a clinical perspective, the relationships between T-LGLL and other borderline and overlapping conditions, including reactive cell expansions, clonal hematopoiesis of indeterminate potential (CHIP) and unrelated clonopathies are not fully established, sometimes making the diagnosis of T cell malignancy challenging. In this review specifically focused on the topic of clonality of T-LGL disorders we will discuss the rationale of the appropriate steps to aid in distinguishing LGLL from its mimics, also attempting to provide new clues to stimulate further investigations designed to move this field forward
The constitutive activation of STAT3 gene and its mutations are at the crossroad between LGL leukemia and autoimmune disorders
Get PDFType T Large Granular Lymphocyte Leukemia (T-LGLL) is a chronic disorder characterized by the abnormal proliferation of clonal cytotoxic T cells. The intriguing association of T-LGLL with autoimmune and inflammatory diseases, the most prominent example being rheumatoid arthritis, raises questions about the underlying pathophysiologic relationships between these disorders which share several biological and clinical features, most notably neutropenia, which is considered as a clinical hallmark. Recent progress in molecular genetics has contributed to a better understanding of pathogenetic mechanisms, thus moving our knowledge in the field of LGL leukemias forward. Focusing on the constitutive activation of STAT3 pathway and the well-established role of STAT3 mutations in T-LGLL, we herein discuss whether the T cell clones occurring in comorbid conditions are the cause or the consequence of the immune-inflammatory associated events. Overall, this review sheds light on the intricate relationships between inflammation and cancer, emphasizing the importance of the STAT3 gene and its activation in the pathophysiology of these conditions. Gaining a deeper understanding of these underlying mechanisms seeks to pave the way for the development of novel targeted therapies for patients affected by inflammation-related cancers
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Not all LGL leukemias are created equal
Get PDF: Large Granular Lymphocyte (LGL) Leukemia is a rare, heterogeneous even more that once thought, chronic lymphoproliferative disorder characterized by the clonal expansion of T- or NK-LGLs that requires appropriate immunophenotypic and molecular characterization. As in many other hematological conditions, genomic features are taking research efforts one step further and are also becoming instrumental in refining discrete subsets of LGL disorders. In particular, STAT3 and STAT5B mutations may be harbored in leukemic cells and their presence has been linked to diagnosis of LGL disorders. On clinical grounds, a correlation has been established in CD8+ T-LGLL patients between STAT3 mutations and clinical features, in particular neutropenia that favors the onset of severe infections. Revisiting biological aspects, clinical features as well as current and predictable emerging treatments of these disorders, we will herein discuss why appropriate dissection of different disease variants is needed to better manage patients with LGL disorders
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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