Thymocyte Selection-associated High-mobility Group Box Research Articles

TOX as a new diagnostic marker for T cell large granular lymphocytic leukaemia.

T cell large granular lymphocytic leukaemia (T-LGLL) is a rare disorder that may underlie otherwise unexplained cytopenias. The identification of T-LGLL cells in bone marrow biopsies can be a challenge, because a robust immunohistochemistry marker is lacking. The markers currently in use (granzyme B, TIA-1 and CD8) are difficult to interpret or lack specificity. Therefore, we investigated whether immunohistochemistry for thymocyte selection-associated high-mobility group box (TOX), a transcription factor that associates with chronic T cell stimulation, could be a reliable tool for the identification of T-LGLL cells. In this retrospective study, expression of TOX in CD8+ cells in bone marrow biopsies of T-LGLL patients (n = 38) was investigated and compared to bone marrow of controls with reactive T cell lymphocytosis (n = 10). All biopsies were evaluated for TOX staining within the CD8-positive T cell population. The controls were essentially negative for TOX, whereas all T-LGLL cases were positive (median = 80%, range = 10-100%), even when bone marrow involvement was subtle. TOX is a highly sensitive marker for the neoplastic cells of T-LGLL and we recommend its use, especially in the diagnostic work-up of patients with unexplained cytopenias.

High TOX expression on CD8+ T cells in pure red cell aplasia.

Thymocyte selection-associated high-mobility group box protein (TOX) is an important molecule regulating the development and exhaustion of T lymphocytes. Our aim is to investigate the role of TOX in the immune pathogenesis of pure red cell aplasia (PRCA). TOX expression of CD8+ lymphocytes from the peripheral blood of patients with PRCA was detected by flow cytometry. Additionally, the expression of immune checkpoint molecules PD1 and LAG3 and cytotoxic molecules perforin and granzyme B of CD8+ lymphocytes was measured. The quantity of CD4+CD25+CD127low T cells was analyzed. TOX expression on CD8+ T lymphocytes in PRCA patients was significantly increased (40.73 [Formula: see text] 16.03 vs. 28.38 [Formula: see text] 12.20). The expression levels of PD1 and LAG3 on CD8+ T lymphocytes in PCRA patients were significantly higher than those in the control group (34.18 [Formula: see text] 13.26 vs. 21.76 [Formula: see text] 9.22 and 14.17 [Formula: see text] 13.74 vs. 7.24 [Formula: see text] 5.44, respectively). The levels of perforin and granzyme in CD8+ T lymphocytes of PRCA patients were 48.60 [Formula: see text] 19.02 and 46.66 [Formula: see text] 25.49, respectively, which were significantly higher than those of the control group (31.46 [Formula: see text] 7.82 and 16.17 [Formula: see text] 4.84, respectively). The number of CD4+CD25+CD127low Treg cells in PRCA patients was significantly decreased (4.30 [Formula: see text] 1.27 vs. 1.75 [Formula: see text] 1.22). In PRCA patients, CD8+ T cells were activated and exhibited overexpression of TOX, PD1, LAG3, perforin, and granzyme B, while regulatory T cells decreased. These findings suggest that T cell abnormality plays a critical role in the pathogenesis of PRCA.

CD8+ T cell dysfunction by TOX intoxication: a protumorigenic event in thetumor microenvironment.

Accumulating evidence suggests the role of cellular components in achieving antitumor to protumor microenvironments. Among the various types of cells within the tumor niche, the state of CD8+ T cells apparently changes from cytotoxic T effector cellsand memory T cells to exhausted CD8+ T cells. These changes in the phenotype of CD8+ T cells promote the protumor microenvironment. Recently, comprehensive experimental data delineated the role of thymocyte selection-associated high-mobility group-box protein (TOX), which regulates the transcriptional process and epigenetic remodeling, with implications in tumor and chronic viral infections. This perspective summarizes the molecular mechanisms that link CD8+ T cells, TOX, and transcriptional and epigenetic reprogramming as well as future directions for determining new avenues of cancer therapeutics.

Single-cell transcriptomics reveal the intratumoral landscape of infiltrated T-cell subpopulations in oral squamous cell carcinoma.

Systematic analysis of tumor‐infiltrating lymphocytes is essential for the development of new cancer treatments and the prediction of clinical responses to immunotherapy. Immunomodulatory drugs are used for the treatment of oral squamous cell carcinoma (OSCC), depending on immune infiltration profiles of the tumor microenvironment. In this study, we isolated 11,866 single T cells from tumors and paired adjacent normal tissues of three patients with OSCC. Using single‐cell RNA sequencing, we identified 14 distinct T‐cell subpopulations within the tumors and 5 T‐cell subpopulations in the adjacent normal tissues and delineated their developmental trajectories. Exhausted CD8+ T cells and regulatory CD4+ T cells (CD4+ Tregs) were enriched in OSCC tumors, potentially linked to tumor immunosuppression. Programmed death protein 1 (PD‐1) and cytotoxic T lymphocyte‐associated protein 4 (CTLA4) were identified as marker genes in exhausted CD8+ T cells, whereas forkhead box P3 (FOXP3) and CTLA4 were identified as markers of CD4+ Tregs. Furthermore, our data revealed that thymocyte selection‐associated high‐mobility group box (TOX) may be a key regulator of T‐cell dysfunction in the OSCC microenvironment. Overexpression of TOX upregulated expression of genes related to T‐cell dysfunction. In vitro experiments demonstrated that cytotoxic activity and proliferation efficiency of CD8+ T cells overexpressing PD‐1 or TOX were reduced. Notable, the transcription factor PRDM1 was found to transactivate TOX expression via a binding motif in the TOX promoter. Our findings provide valuable insight into the functional states and heterogeneity of T‐cell populations in OSCC that could advance the development of novel therapeutic strategies.

High-mobility group box (TOX) antibody a useful tool for the identification of B and T cell subpopulations.

Thymocyte selection-associated high-mobility group box (TOX) is a DNA-binding factor that is able to regulate transcription by modifying local chromatin structure and modulating the formation of multi-protein complexes. TOX has multiple roles in the development of the adaptive immune system including development of CD4 T cells, NK cells and lymph node organogenesis. However very few antibodies recognizing this molecule have been reported and no extensive study of the expression of TOX in reactive and neoplastic lymphoid tissue has been performed to date. In the present study, we have investigated TOX expression in normal and neoplastic lymphoid tissues using a novel rat monoclonal antibody that recognizes its target molecule in paraffin-embedded tissue sections. A large series of normal tissues and B- and T-cell lymphomas was studied, using whole sections and tissue microarrays. We found that the majority of precursor B/T lymphoblastic, follicular and diffuse large B-cell lymphomas, nodular lymphocyte-predominant Hodgkin lymphomas and angioimmunoblastic T-cell lymphomas strongly expressed the TOX protein. Burkitt and mantle cell lymphomas showed TOX expression in a small percentage of cases. TOX was not found in the majority of chronic lymphocytic leukemia, myelomas, marginal zone lymphomas and classical Hodgkin lymphomas. In conclusion, we describe for the first time the expression of TOX in normal and neoplastic lymphoid tissues. The co-expression of TOX and PD-1 identified in normal and neoplastic T cells is consistent with recent studies identifying TOX as a critical regulator of T-cell exhaustion and a potential immunotherapy target. Its differential expression may be of diagnostic relevance in the differential diagnosis of follicular lymphoma, the identification of the phenotype of diffuse large B-cell lymphoma and the recognition of peripheral T-cell lymphoma with a follicular helper T phenotype.

Value of TOX Immunoexpression in the Diagnosis of Early Mycosis Fungoides

Background: The lack of a specific marker to differentiate malignant from reactiveT-cells makes a definite diagnosis difficult in patients suspected of having mycosisfungoides. This study has evaluated value of thymocyte selection-associated highmobility group box factor expression in the differentiation of early mycosis fungoidesfrom a benign inflammatory dermatosis.Methods:We selected 22 mycosis fungoides cases, 18 cases suspicious for mycosisfungoides, and 12 cases of eczematous dermatitis from patients who attendedDermatology Clinic, Shiraz University of Medical Sciences (2008-2015). The obtainedskin biopsies were immunostained for thymocyte selection-associated high mobilitygroup box factor antigen in addition to pan T cell markers. The slides were evaluatedfor the percentage of tumor cells and intensity of immunoreactivity.Results: From 22 cases of mycosis fungoides, 40.9% showed massive infiltrationof thymocyte selection-associated high mobility group box factor-positive lymphocytes(>30%) with high (3+) intensity in the epidermis; there was no case negative forthymocyte selection-associated high mobility group box factor expression. Only oneeczematous dermatitis case had expression of thymocyte selection-associated highmobility group box factor-positive lymphocytes (>30%) with high intensity and 4 caseswere negative for thymocyte selection-associated high mobility group box factorexpression. The frequency of thymocyte selection-associated high mobility groupbox factor expressing lymphocytes was higher in biopsies from mycosis fungoidescompared to eczematous dermatitis (P<0.05). CD7- cases expressed more thymocyteselection-associated high mobility group box factor-positive lymphocytes in the dermisand epidermis, which were significantly correlated (P=0.013).Conclusion: Thymocyte selection-associated high mobility group box factor, as apositive marker, in combination with pan T cell markers (especially CD7-) can be usefulto detect mycosis fungoides malignant lymphoid cells.

TOX expression decreases with progression of colorectal cancers and is associated with CD4 T-cell density and Fusobacterium nucleatum infection

Fusobacterium nucleatum in the tumor microenvironment plays an important role in the development of colorectal cancer. The underlying mechanism of action, however, remains to be elucidated. We evaluated the relation of F nucleatum amount to thymocyte selection-associated high-mobility group box (TOX) protein expression and CD4+ T-cell density in 138 human colorectal tissues. TOX expression and CD4+ T-cell density in Fnucleatum-negative tissues were significantly higher compared to those in Fnucleatum-positive tissues (P < .001 and P = .002, respectively). We found a negative correlation between F nucleatum abundance and TOX expression (P < .001) and CD4+ T-cell density (P < .001). TOX expression in normal mucosa, hyperplastic polyps, and adenomas was significantly higher than in sessile serrated adenomas and different stages of carcinomas (P < .05). Moreover, CD4+ T-cell density in high-TOX expression tissues was significantly higher than in low-TOX expression tissues (P = .003). A positive correlation was found between TOX expression and CD4+ T-cell density in colorectal tissues (Spearman correlation coefficient: 0.362, 95% confidence interval: 0.051-0.641, P = .022). Our findings suggest that F nucleatum may suppress antitumor immune responses by decreasing CD4+ T-cell density and TOX expression in the progression of colorectal cancer.

Long noncoding RNA expression profile reveals lncRNAs signature associated with extracellular matrix degradation in kashin-beck disease

Kashin-Beck disease (KBD) is a deformative, endemic osteochondropathy involving degeneration and necrosis of growth plates and articular cartilage. The pathogenesis of KBD is related to gene expression and regulation mechanisms, but long noncoding RNAs (lncRNAs) in KBD have not been investigated. In this study, we identified 316 up-regulated and 631 down-regulated lncRNAs (≥ 2-fold change) in KBD chondrocytes using microarray analysis, of which more than three-quarters were intergenic lncRNAs and antisense lncRNAs. We also identified 232 up-regulated and 427 down-regulated mRNAs (≥ 2-fold change). A lncRNA-mRNA correlation analysis combined 343 lncRNAs and 292 mRNAs to form 509 coding-noncoding gene co-expression networks (CNC networks). Eleven lncRNAs were predicted to have cis-regulated target genes, including NAV2 (neuron navigator 2), TOX (thymocyte selection-associated high mobility group box), LAMA4 (laminin, alpha 4), and DEPTOR (DEP domain containing mTOR-interacting protein). The differentially expressed mRNAs in KBD significantly contribute to biological events associated with the extracellular matrix. Meanwhile, 34 mRNAs and 55 co-expressed lncRNAs constituted a network that influences the extracellular matrix. In the network, FBLN1 and LAMA 4 were the core genes with the highest significance. These novel findings indicate that lncRNAs may play a role in extracellular matrix destruction in KBD.

A Human Lin- CD123+ CD127low Population Endowed with ILC Features and Migratory Capabilities Contributes to Immunopathological Hallmarks of Psoriasis.

Innate lymphoid cells (ILC) are members of a heterogeneous family with a lymphoid origin that mimics the T helper (Th) cytokine profile. ILC are involved in early effector cytokine-mediated responses during infections in peripheral tissues. ILC also play an important role in chronic skin inflammatory diseases, including psoriasis. Although classical ILC express CD127, it has been recently reported that the presence of non-classical CD127− ILC populations and an early ILC precursor (EILP) CD127low. ILC development has predominately been investigated in mouse models. However, in humans, different transcription factors have been described for ILC identification. NFIL3 (nuclear factor, IL-3 regulated) is crucial for ILC development in response to IL-7. CD123 (IL-3Rα) is usually used to exclude basophils during ILC identification, however, it is unknown if in response to IL-3, NFIL3 could be relevant to induce ILC features in Lin− CD123+ populations in addition, is also unknown whether peripheral blood (PB) population with ILC features may have skin-homing potential to participate in skin inflammatory chronic diseases. Here, we report a Lin− CD123+ CD127low CD7+ CLA+ population that share some phenotypic properties with basophils, but expresses several transcription factors for ILC commitment such as inhibitor of DNA binding 2 (Id2), NFIL3, promyelocytic leukemia zinc finger (PLZF), thymocyte selection-associated high-mobility group box protein (TOX), and T cell factor-1 (TCF-1). In addition, this population expresses different ILC markers: CD132, CD90, CD161, α4 integrin, c-Kit, CRTH2, AhR, and IL-23R. IL-3 prevents apoptosis and increases their NFIL3, TOX, and PLZF expression. In PB, the CD123+ CD127low population is predominantly a conspicuous population that expresses T-bet and RORγt. The Lin− CD123+ CD127low population in PB has a limited Th type cytokine expression and highly expresses IL-8. The Lin− CD123+ CD127low population expresses skin-homing receptors (cutaneous lymphocyte antigen and CXCR4) and transmigrates through endothelial cells in response to SDF-1. An equivalent Lin− CD123low population was identified in control skin, which shows a broader phenotypic diversity and cytokine production, including IL-22 and IL-17. Remarkably, the CD123low population in the lesion and non-lesion skin of psoriasis patients expresses IL-17 and IL-22. Our findings suggest the identification of an alternative Lin− CD123+ CD127low population with ILC features endowed with migratory capabilities that might contribute to immunopathological hallmarks of psoriasis.

TOX expression in cutaneous T-cell lymphomas: an adjunctive diagnostic marker that is not tumour specific and not restricted to the CD4(+) CD8(-) phenotype.

TOX (thymocyte selection-associated high-mobility group box) was shown to be aberrantly expressed in mycosis fungoides (MF) and Sézary syndrome (SS) and is suggested to have additional diagnostic value. However, data on expression in other types of cutaneous T-cell lymphoma (CTCL) are scarce and it is unknown whether TOX is expressed only by MF with a CD4(+) CD8(-) phenotype. To investigate TOX expression in various types of CTCL with different T-cell phenotypes. Immunohistochemical expression of TOX was evaluated on 153 skin biopsies of 132 patients with CTCL and 60 patients with benign inflammatory dermatoses (BIDs). TOX was expressed by >50% of the neoplastic T cells in 49 of 59 patients (83%) with MF and in 19 of 22 patients (86%) with SS. The TOX(+) cases of MF included 34 of 35 cases (97%) with a CD4(+) CD8(-) phenotype, but also five of eight cases (63%) with a CD4(-) CD8(+) phenotype and 10 of 16 cases (63%) with a CD4(-) CD8(-) phenotype. TOX expression in other types of CTCL was common but showed variable intensity. Although only one of 60 patients (2%) with a BID expressed TOX in >50% of the skin-infiltrating T cells, some caution is warranted, as the majority of BIDs had TOX(+) T cells varying between 11% and 50%. TOX expression is not tumour specific, is not restricted to CTCL with a CD4(+) CD8(-) phenotype, and, on its own, is insufficient for diagnosis of CTCL. However, it may have an adjunctive diagnostic role in conjunction with other clinical and histological data.

TOX expression in cutaneous B-cell lymphomas.

Thymocyte selection-associated high-mobility group box (TOX) is aberrantly expressed in cutaneous T-cell lymphomas. In a recent study, TOX expression was noted unexpectedly in the follicle center (germinal center) B-cells of reactive lymph nodes and tonsils, used as external controls. To evaluate whether TOX is also expressed by cutaneous B-cell lymphomas, TOX immunohistochemistry was performed on skin biopsies of 44 patients with primary and secondary cutaneous B-cell proliferations. TOX was expressed not only in the reactive follicle center cells of lymph nodes, tonsils, cutaneous lymphoid hyperplasia, and primary cutaneous marginal zone lymphomas, but also by the neoplastic follicle center cells of 16/17 patients with primary cutaneous follicle center lymphoma (PCFCL) and 7/7 patients with cutaneous manifestations of systemic follicular lymphoma (FL). Notably, TOX showed a very similar expression pattern as BCL6, a marker of germinal center B-cells. In 4/10 patients with a BCL6+ primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL,LT) and in 2/2 patients with a secondary cutaneous BCL6+ diffuse large B-cell lymphoma (DLBCL), TOX was expressed by more than 50 % of the neoplastic B-cells. In contrast, in 3/3 BCL6− PCDLBCL,LT, TOX was completely negative or weakly expressed by a minor proportion of the neoplastic B-cells. In conclusion, TOX is expressed not only by neoplastic T-cells, but also by both reactive and neoplastic follicle center (germinal center) B-cells and a proportion of BCL6+ PCDLBCL,LT and secondary cutaneous BCL6+ DLBCL. The functional significance of TOX expression in reactive and neoplastic B-cells remains to be elucidated.

Thymocyte Selection-Associated High-Mobility Group Box Protein (TOX) Induces Genomic Instability in T-Cell Acute Lymphoblastic Leukemia

MYC and NOTCH are major oncogenic drivers in T-cell Acute Lymphoblastic Leukemia (T-ALL), yet additional collaborating genetic lesions likely collaborate to induce frank malignancy. To identify these factors, a large-scale transgenic screen was completed where 38 amplified and over-expressed genes found in human T-ALL were assessed for accelerating leukemia onset in the zebrafish transgenic model. From this analysis, Thymocyte selection-associated homeobox protein (TOX) synergized with both MYC and NOTCH to induce T-ALL. TOX is dynamically regulated in T cell development with peak expression occurring when thymocytes are actively undergoing T cell receptor (TCR) recombination. TOX is best known for regulating the specification of the mature CD4+ T cells. Despite TOX being genomically amplified in a subset of human and mouse T-ALL and being overexpressed in 100% of human T-ALL, a role for TOX in regulating leukemogenesis has not been reported. Characterization of zebrafish T-ALLs revealed that TOX expands the overall number of malignant T-ALL clones and promoted genomic instability as assessed by changes in DNA content. To identify TOX binding partners, antibody immunoprecipitation studies were performed followed by Tandem Mass Spectrometry. TOX was found to interact with KU70/KU80 but not other DNA repair enzymes including LigaseIV, DNA-PKC, or XRCC4. These results were verified by Western blot analysis and reciprocal immunoprecipitation studies using antibodies specific to KU70/KU80 both in the absence and presence of DNAseI treatment. Given that TOX elevated genomic instability in the zebrafish model and bound specifically to KU70/KU80 – the initiating factors required for Non-Homologous End Joining (NHEJ) repair - we hypothesized that TOX is a negative regulator of double-strand break repair. Fluorescent repair assays were completed in 3T3 fibroblasts and confirmed that TOX inhibits Non-Homologous End Joining (NHEJ). Both the nuclear localization signal and HMG-box were required for the ability of TOX to inhibit double-strand break repair. Dynamic real-time imaging studies confirmed that TOX suppresses recruitment of fluorescent-tagged KU70 to DNA breaks. Importantly, TOX loss of function increased NHEJ in human T-ALL cells and reduced time to DNA repair as assessed by fluorescent Traffic Light Reporter assays and quantitative assessment of 53BP1 and γH2A.X foci resolution following irradiation. Given the prominent role TOX has in T cell development and its coordinated regulation during active TCRβ and TCRα rearrangement, it is likely that the normal function of TOX is to transiently suppress the NHEJ pathway during Recombination-Activating Gene (RAG)-mediated recombination. Prolonging the time to DNA repair would likely facilitate long-range repair across VDJ segments. In the setting of T-ALL, TOX is aberrantly re-activated, thereby suppressing KU70/KU80 function to promote genomic instability and ultimately elevating rates at which acquired mutations and rearrangements are amassed in developing pre-malignant T cells. DisclosuresNo relevant conflicts of interest to declare.

155: STAT5 regulation of TOX: Its dependence on IL-2 and role in cancer

The Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) pathway represents a rapid membrane to nucleus signaling system used by cytokines, hormones and growth factors. STAT5 is one of the seven STATs and is a key signaling protein which binds to chromatin at IFN-γ activation site (GAS motifs) and leads to the activation or repression of target genes involved in cell differentiation, proliferation and survival. In this study, several genes directly regulated by STAT5 were identified using chromatin immunoprecipitation in human CD8 + T lymphocytes. Mapping of the genomic fragments revealed that approximately 50% of the target sites were either in the proximal promoter region or introns of genes. Of the 183 STAT5 responsive binding sites identified in CD8 + T cells, almost a fourth contained the canonical GAS motif. Bioinformatic analyses, identified several target-genes whose aberrant functions are associated with malignant transformation of cells, consistent with the frequent dysregulation of STAT5 noted in various cancers. We have identified two other genes regulated by STAT5 and an interesting gene gene identified here is TOX: which is a differentiation program of developing T-cells [1] , [2] . The STAT5 binding site identified here, mapped to an internal intron within the TOX gene. The histone methylation marks too were indicative of an active enhancer region. Mining for information about promoter/TSS on the UCSC genome browser, revealed the presence of a typical GAS motif. An upregulation of TOX was observed in activated CD8 + T cells upon stimulation with IL-2. Although its role is T cell development is well studied, its role in cancers is less known. Various studies have shown the association between TOX subfamily of genes and cancer [3] , [4] . Due to its role in cellular proliferation and differentiation, TOX could have implications in cancer therapeutics. In conclusion, this study identified a role for STAT5 in the regulation of TOX in human T lymphocytes. Its role in cancer is under investigation. TOX (Thymocyte Selection-Associated High Mobility Group Box).