A skewed distribution and increased PD-1+Vβ+CD4+/CD8+ T cells in patients with acute myeloid leukemia

Overexpression of LAG-3: a potential indicator of low immune function in tuberculosis

Background

Tuberculosis (TB) persists as a global health challenge, with its treatment hampered by the side effects of long-term combination drug therapies and the growing issue of drug resistance. Therefore, the development of novel therapeutic strategies is critical. This study focuses on the role of immune checkpoint molecules (ICs) and functions of CD8+ T cells in the search for new potential targets against TB.

Methods

We conducted differential expression genes analysis and CD8+ T cell functional gene analysis on 92 TB samples and 61 healthy individual (HI) samples from TB database GSE83456, which contains data on 34,603 genes. The GSE54992 dataset was used to validated the findings. Additionally, a cluster analysis on single-cell data from primates infected with mycobacterium tuberculosis and those vaccinated with BCG was performed.

Results

The overexpression of LAG-3 gene was found as a potentially important characteristic of both pulmonary TB (PTB) and extrapulmonary TB (EPTB). Further correlation analysis showed that LAG-3 gene was correlated with GZMB, perforin, IL-2 and IL-12. A significant temporal and spatial variation in LAG-3 expression was observed in T cells and macrophages during TB infection and after BCG vaccination.

Conclusion

LAG-3 was overexpressed in TB samples. Targeting LAG-3 may represent a potential therapeutic target for tuberculosis.

T cell-mediated tumor killing sensitivity gene signature-based prognostic score for acute myeloid leukemia

BACKGROUND AND OBJECTIVE

Acute myeloid leukemia (AML) is an aggressive, heterogenous hematopoetic malignancies with poor long-term prognosis. T-cell mediated tumor killing plays a key role in tumor immunity. Here, we explored the prognostic performance and functional significance of a T-cell mediated tumor killing sensitivity gene (GSTTK)-based prognostic score (TTKPI).

METHODS

Publicly available transcriptomic data for AML were obtained from TCGA and NCBI-GEO. GSTTK were identified from the TISIDB database. Signature GSTTK for AML were identified by differential expression analysis, COX proportional hazards and LASSO regression analysis and a comprehensive TTKPI score was constructed. Prognostic performance of the TTKPI was examined using Kaplan-Meier survival analysis, Receiver operating curves, and nomogram analysis. Association of TTKPI with clinical phenotypes, tumor immune cell infiltration patterns, checkpoint expression patterns were analysed. Drug docking was used to identify important candidate drugs based on the TTKPI-component genes.

RESULTS

From 401 differentially expressed GSTTK in AML, 24 genes were identified as signature genes and used to construct the TTKPI score. High-TTKPI risk score predicted worse survival and good prognostic accuracy with AUC values ranging from 75 to 96%. Higher TTKPI scores were associated with older age and cancer stage, which showed improved prognostic performance when combined with TTKPI. High TTKPI was associated with lower naïve CD4 T cell and follicular helper T cell infiltrates and higher M2 macrophages/monocyte infiltration. Distinct patterns of immune checkpoint expression corresponded with TTKPI score groups. Three agents; DB11791 (Capmatinib), DB12886 (GSK-1521498) and DB14773 (Lifirafenib) were identified as candidates for AML.

CONCLUSION

A T-cell mediated killing sensitivity gene-based prognostic score TTKPI showed good accuracy in predicting survival in AML. TTKPI corresponded to functional and immunological features of the tumor microenvironment including checkpoint expression patterns and should be investigated for precision medicine approaches.

Higher PD-1/Tim-3 expression on IFN-γ+ T cells is associated with poor prognosis in patients with acute myeloid leukemia

With the success of immune checkpoint inhibitors (ICI), such as anti- programmed death-1 (PD-1) antibody for solid tumors and lymphoma immunotherapy, a number of clinical trials with ICIs have been attempted for acute myeloid leukemia (AML) immunotherapy; however, limited clinical efficacy has been reported. This may be due to the heterogeneity of immune microenvironments and various degrees of T cell exhaustion in patients and may be involved in the IFN-γ pathway. In this study, we first characterized the percentage of PD-1+ and T cell immunoglobulin mucin-domain-containing-3 (Tim-3) +IFN-γ+ T cells in peripheral blood (PB) in AML compared with healthy individuals (HIs) by flow cytometry and further discussed the possibility of the reversal of T cell exhaustion to restore the secretion capacity of cytokines in T cells in AML based on blockade of PD-1 or Tim-3 (anti-PD-1 and anti-Tim-3 antibody) in vitro using a cytokine protein chip. A significantly increased percentage of PD-1+, Tim-3+, and PD-1+Tim-3+ IFN-γ+ T cells was observed in PB from patients with AML in comparison with HIs. Moreover, higher PD-1+IFN-γ+CD3+/CD8+ T cell levels were associated with poor overall survival in AML patients. Regarding leukemia cells, the percentage of Tim-3 in CD117+CD34+ AML cells was positively correlated with PD-1 in IFN-γ+CD4+ T cells. Furthermore, blocking PD-1 and Tim-3 may involve multiple cytokines and helper T cell subsets, mainly Th1 and Treg cells. Blockade of PD-1 or Tim-3 tends to restore cytokine secretion to a certain extent, a synergistic effect shown by the co-blockade of PD-1 and Tim-3. However, we also demonstrated the heterogeneity of secretory cytokines in ICI-treated T cells in AML patients.

The potential role of the thymus in immunotherapies for acute myeloid leukemia

Understanding the factors which shape T-lymphocyte immunity is critical for the development and application of future immunotherapeutic strategies in treating hematological malignancies. The thymus, a specialized central lymphoid organ, plays important roles in generating a diverse T lymphocyte repertoire during the infantile and juvenile stages of humans. However, age-associated thymic involution and diseases or treatment associated injury result in a decline in its continuous role in the maintenance of T cell-mediated anti-tumor/virus immunity. Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that mainly affects older adults, and the disease's progression is known to consist of an impaired immune surveillance including a reduction in naïve T cell output, a restriction in T cell receptor repertoire, and an increase in frequencies of regulatory T cells. As one of the most successful immunotherapies thus far developed for malignancy, T-cell-based adoptive cell therapies could be essential for the development of a durable effective treatment to eliminate residue leukemic cells (blasts) and prevent AML relapse. Thus, a detailed cellular and molecular landscape of how the adult thymus functions within the context of the AML microenvironment will provide new insights into both the immune-related pathogenesis and the regeneration of a functional immune system against leukemia in AML patients. Herein, we review the available evidence supporting the potential correlation between thymic dysfunction and T-lymphocyte impairment with the ontogeny of AML (II-VI). We then discuss how the thymus could impact current and future therapeutic approaches in AML (VII). Finally, we review various strategies to rejuvenate thymic function to improve the precision and efficacy of cancer immunotherapy (VIII).

A perspective of immunotherapy for acute myeloid leukemia: Current advances and challenges

During the last decade, the underlying pathogenic mechanisms of acute myeloid leukemia (AML) have been the subject of extensive study which has considerably increased our understanding of the disease. However, both resistance to chemotherapy and disease relapse remain the principal obstacles to successful treatment. Because of acute and chronic undesirable effects frequently associated with conventional cytotoxic chemotherapy, consolidation chemotherapy is not feasible, especially for elderly patients, which has attracted a growing body of research to attempt to tackle this problem. Immunotherapies for acute myeloid leukemia, including immune checkpoint inhibitors, monoclonal antibodies, dendritic cell (DC) vaccines, together with T-cell therapy based on engineered antigen receptor have been developed recently. Our review presents the recent progress in immunotherapy for the treatment of AML and discusses effective therapies that have the most potential and major challenges.

Increased PD-1+Foxp3+ γδ T cells associate with poor overall survival for patients with acute myeloid leukemia

Problems

γδ T cells are essential for anti-leukemia function in immunotherapy, however, γδ T cells have different functional subsets, including regulatory cell subsets expressing the Foxp3. Whether they are correlated with immune-checkpoint mediated T cell immune dysfunction remains unknown in patients with acute myeloid leukemia (AML).

Methods

In this study, we used RNA-seq data from 167 patients in TCGA dataset to analyze the correlation between PD-1 and FOXP3 genes and these two genes' association with the prognosis of AML patients. The expression proportion of Foxp3⁺/PD-1⁺ cells in γδ T cells and two subgroups Vδ1 and Vδ2 T cells were performed by flow cytometry. The expression level of FOXP3 and PD-1 genes in γδ T cells were sorted from peripheral blood by MACS magnetic cell sorting technique were analyzed by quantitative real-time PCR.

Results

We found that PD-1 gene was positively correlated with FOXP3 gene and highly co-expressed PD-1 and FOXP3 genes were associated with poor overall survival (OS) from TCGA database. Then, we detected a skewed distribution of γδ T cells with increased Vδ1 and decreased Vδ2 T cell subsets in AML. Moreover, significantly higher percentages of PD-1⁺ γδ, Foxp3⁺ γδ, and PD-1⁺Foxp3⁺ γδ T cells were detected in de novo AML patients compared with healthy individuals. More importantly, AML patients containing higher PD-1⁺Foxp3⁺ γδ T cells had lower OS, which might be a potential therapeutic target for leukemia immunotherapy.

Conclusion

A significant increase in the PD-1⁺Foxp3⁺ γδ T cell subset in AML was associated with poor clinical outcome, which provides predictive value for the study of AML patients.

Immune checkpoint alterations and their blockade in COVID-19 patients

Coronavirus disease 2019 (COVID-19) is a highly contagious disease that seriously affects people's lives. Immune dysfunction, which is characterized by abnormal expression of multiple immune checkpoint proteins (ICs) on immune cells, is associated with progression and poor prognosis for tumors and chronic infections. Immunotherapy targeting ICs has been well established in modulating immune function and improving clinical outcome for solid tumors and hematological malignancies. The role of ICs in different populations or COVID-19 stages and the impact of IC blockade remains unclear. In this review, we summarized current studies of alterations in ICs in COVID-19 to better understand immune changes and provide strategies for treating COVID-19 patients, particularly those with cancer.

The role of PD-1/PD-L1 and application of immune-checkpoint inhibitors in human cancers

Programmed cell death protein-1 (PD-1) is a checkpoint receptor expressed on the surface of various immune cells. PD-L1, the natural receptor for PD-1, is mainly expressed in tumor cells. Studies have indicated that PD-1 and PD-L1 are closely associated with the progression of human cancers and are promising biomarkers for cancer therapy. Moreover, the interaction of PD-1 and PD-L1 is one of the important mechanism by which human tumors generate immune escape. This article provides a review on the role of PD-L1/PD-1, mechanisms of immune response and resistance, as well as immune-related adverse events in the treatment of anti-PD-1/PD-L1 immunotherapy in human cancers. Moreover, we summarized a large number of clinical trials to successfully reveal that PD-1/PD-L1 Immune-checkpoint inhibitors have manifested promising therapeutic effects, which have been evaluated from different perspectives, including overall survival, objective effective rate and medium progression-free survival. Finally, we pointed out the current problems faced by PD-1/PD-L1 Immune-checkpoint inhibitors and its future prospects. Although PD-1/PD-L1 immune checkpoint inhibitors have been widely used in the treatment of human cancers, tough challenges still remain. Combination therapy and predictive models based on integrated biomarker determination theory may be the future directions for the application of PD-1/PD-L1 Immune-checkpoint inhibitors in treating human cancers.

A Focus on Intermediate-Risk Acute Myeloid Leukemia: Sub-Classification Updates and Therapeutic Challenges

Acute myeloid leukemia (AML) represents a heterogeneous group of hematopoietic neoplasms deriving from the abnormal proliferation of myeloid progenitors in the bone marrow. Patients with AML may have highly variable outcomes, which are generally dictated by individual clinical and genomic characteristics. As such, the European LeukemiaNet 2017 and 2022 guidelines categorize newly diagnosed AML into favorable-, intermediate-, and adverse-risk groups, based on their molecular and cytogenetic profiles. Nevertheless, the intermediate-risk category remains poorly defined, as many patients fall into this group as a result of their exclusion from the other two. Moreover, further genomic data with potential prognostic and therapeutic influences continue to emerge, though they are yet to be integrated into the diagnostic and prognostic models of AML. This review highlights the latest therapeutic advances and challenges that warrant refining the prognostic classification of intermediate-risk AML.

High TRGV 9 Subfamily Expression Marks an Improved Overall Survival in Patients With Acute Myeloid Leukemia

Background

Heterogeneous T cells in acute myeloid leukemia (AML) have the combinatorial variety generated by different T cell receptors (TCRs). γδ T cells are a distinct subgroup of T cells containing TCRγ (TRGV) and TCRδ (TRDV) subfamilies with diverse structural and functional heterogeneity. Our previous study showed that clonally expanded TRDV T cells might benefit the immune response directed against AML. However, the features of the TRGV repertoire in AML remain unknown. To fully characterize the features of γδ T cells, we analyzed the distribution and clonality of TRGV I-III subfamilies (TRGV II is also termed TRVG 9), the proportions of γδ T cell subsets, and their effects on the overall survival (OS) of patients with AML.

Methods

In this study, the complementarity-determining region 3 (CDR3) size of TRGV subfamilies in γδ T cells of peripheral blood (PB) from de novo AML patients were analyzed by Genescan analysis. Expression levels of TRGV subfamilies were performed by real-time quantitative PCR. The proportions of total γδ T cells and their Vγ9⁺ Vδ2⁺ T cells subsets were detected by multicolor flow cytometry assay. We further compared the correlation among the TRGV gene expression levels, the proportion of Vγ9⁺ Vδ2⁺ T cells, and OS in AML.

Results

We first found that the distribution pattern and clonality of TRGV subfamilies were changed. The expression frequencies and gene expression levels of three TRGV subfamilies in AML samples were significantly lower than those in healthy individuals (HIs). Compared with HIs, the proportions of total γδ T cells and Vγ9⁺ Vδ2⁺ T cells were also significantly decreased in patients with AML. In addition, patients with AML who had higher expression levels of the TRGV gene and higher proportion of Vγ9⁺ Vδ2⁺ T cells showed better OS than their counterparts. Furthermore, high expression levels of TRGV 9 and proportion of Vγ9⁺ Vδ2⁺ T cells were identified as independent protective factors for complete remission in patients with AML.

Conclusions

The restriction of TRGV usage might be related to the preference of usage of γδ T cells. Higher expression of TRGV subfamilies might be associated with better OS in AML. Higher TRGV 9 expression and increased Vγ9⁺ Vδ2⁺ T cells subfamilies might indicate a better prognosis in patients with AML.

Increased TOX expression concurrent with PD-1, Tim-3, and CD244 expression in T cells from patients with acute myeloid leukemia

BACKGROUND

T cell dysregulation is a common event in leukemia. Recent findings have indicated that aberrant expression of immune checkpoint proteins may be associated with disease relapse and progression in acute myeloid leukemia (AML). TOX, a transcription factor in the HMG-box protein superfamily, was found to be a potential target for immunotherapy not only in solid tumors but also in hematological malignancies. However, little is known about TOX expression and co-expression with immune checkpoint proteins or the exhausted phenotype in the T cell subsets in AML. Thus, in this study, we analyzed TOX expression and co-expression with PD-1, Tim-3, and CD244 in T cells.

METHODS

TOX expression and co-expression with PD-1, Tim-3, and CD244 in CD3+, CD4+, regulatory T (Treg), and CD8+ T cells were analyzed by multi-color fluorescent flow cytometry in peripheral blood (PB) and bone marrow (BM) samples from patients with de novo AML and AML in complete remission (CR) and healthy individuals (HIs).

RESULTS

A significantly increased percentage of TOX+CD3+, CD4+, and CD8+ T cells was found in PB from patients with de novo AML in comparison with HIs. Double-positive TOX+CD244+, TOX+PD-1+, and TOX+Tim-3+ T cells markedly increased in the CD3+, CD4+, and CD8+ T cell populations in de novo AML patients compared with HIs, and similar trends were demonstrated for TOX+Tim-3+CD3+/CD4+/CD8+ T cells in de novo AML compared with AML-CR patients. In addition, the number of TOX+, TOX+PD-1+, and TOX+Tim-3+Treg cells significantly increased in de novo AML patients compared with HIs, and TOX+PD-1+Treg cells were higher in de novo AML compared with AML-CR patients. Moreover, TOX positively correlated with Tim-3 expression in CD8+ and Treg cells, and a positive correlation between the expression of TOX+ CD4+ and CD244+CD4+ T cells was found. Furthermore, an increased percentage of TOX+Tim-3+ T cells in BM was also found in de novo AML patients compared with HIs.

CONCLUSIONS

Increased TOX concurrent with PD-1, Tim-3, and CD244 in T cells may contribute to T cell exhaustion and impair their function in AML. Such exhausted T cells may be partially revised when AML patients achieve CR after chemotherapy. TOX may be considered a potential target for reversing T cell exhaustion and improving T cell function in AML.

Changes of Cell Adhesion Molecules and T Cell Subset Populations in Acute Myeloid Leukemia Patients Undergoing Intravenous Administration of Cytarabine Supplemented with Idarubicin

Objective. The present study aimed at investigating the efficacy and safety of intravenous administration of cytarabine supplemented with idarubicin in treating acute myeloid leukemia (AML) patients undergoing first attack and its effects on serum levels of cell adhesion molecules, cytokines in response to inflammation, and T cell subset populations in acute myeloid leukemia (AML) patients undergoing first attack. Methods. A total of 88 AML patients eligible for inclusion and exclusion criteria participated in the study and were randomly assigned into the control group (n = 44) in which the patients received intravenous administration of cytarabine and daunorubicin and the study group (n = 44) in which the patients received intravenous administration of cytarabine and idarubicin. Clinical response, incidence of adverse reactions, and quality of life 3 months after therapy were evaluated. Soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), IL-10, and IL-35 were measured by ELISA methods. Phenotypic characteristics of T cell subsets including CD4+, CD8+, CD4+IL-10 Tregs, and CD4+CD25+CD127−Foxp3+ Tregs were analyzed by flow cytometry. Results. The clinical response rate of the study group was better than that of the control group (65.91% vs. 45.45%) ( $P<0.05$ ). After treatment, the study group revealed significantly lower levels of sICAM-1, sVCAM-1, IL-10, and IL-35, a lower proportion of Tregs, a higher rate of CD4+/CD8+ T cells, along with increased scores of the Karnofsky Performance Scale (KPS) compared with the control group ( $P<0.05$ ). The incidence rate of adverse reactions in the study group was lower than that in the control group (34.09% vs. 61.36%) ( $P<0.05$ ). Conclusion. These findings demonstrate that intravenous administration of cytarabine supplemented with idarubicin can improve the immune function and quality of life of AML patients, and this combination drug therapy is effective and safe for AML.

Higher Expression of WT1 With Lower CD58 Expression may be Biomarkers for Risk Stratification of Patients With Cytogenetically Normal Acute Myeloid Leukemia

Background: Cytogenetics at diagnosis is the most important prognostic factor for adult acute myeloid leukemia (AML), but nearly 50% of AML patients who exhibit cytogenetically normal AML (CN-AML) do not undergo effective risk stratification. Therefore, the development of potential biomarkers to further define risk stratification for CN-AML patients is worth exploring. Methods: Transcriptome data from 163 cases in the GSE12417-GPL96 dataset and 104 CN-AML patient cases in the GSE71014-GPL10558 dataset were downloaded from the Gene Expression Omnibus database for overall survival (OS) analysis and validation. Results: The combination of Wilms tumor 1 (WT1) and cluster of diffraction 58 (CD58) can predict the prognosis of CN-AML patients. High expression of WT1 and low expression of CD58 were associated with poor OS in CN-AML. Notably, when WT1 and CD58 were used to concurrently predict OS, CN-AML patients were divided into three groups: low risk, WT1^lowCD58^high; intermediate risk, WT1^highCD58^high or WT1^lowCD58^low; and high risk, WT1^highCD58^low. Compared with low-risk patients, intermediate- and high-risk patients had shorter survival time and worse OS. Furthermore, a nomogram model constructed with WT1 and CD58 may personalize and reveal the 1-, 2-, 3-, 4-, and 5-year OS rate of CN-AML patients. Both time-dependent receiver operating characteristics and calibration curves suggested that the nomogram model demonstrated good performance. Conclusion: Higher expression of WT1 with lower CD58 expression may be a potential biomarker for risk stratification of CN-AML patients. Moreover, a nomogram model constructed with WT1 and CD58 may personalize and reveal the 1-, 2-, 3-, 4-, and 5-year OS rates of CN-AML patients.

Acute Myeloid Leukemia: Is It T Time?

Acute myeloid leukemia (AML) is a heterogeneous disease driven by impaired differentiation of hematopoietic primitive cells toward myeloid lineages (monocytes, granulocytes, red blood cells, platelets), leading to expansion and accumulation of "stem" and/or "progenitor"-like or differentiated leukemic cells in the bone marrow and blood. AML progression alters the bone marrow microenvironment and inhibits hematopoiesis' proper functioning, causing sustained cytopenia and immunodeficiency. This review describes how the AML microenvironment influences lymphoid lineages, particularly T lymphocytes that originate from the thymus and orchestrate adaptive immune response. We focus on the elderly population, which is mainly affected by this pathology. We discuss how a permissive AML microenvironment can alter and even worsen the thymic function, T cells' peripheral homeostasis, phenotype, and functions. Based on the recent findings on the mechanisms supporting that AML induces quantitative and qualitative changes in T cells, we suggest and summarize current immunotherapeutic strategies and challenges to overcome these anomalies to improve the anti-leukemic immune response and the clinical outcome of patients.

Increased TOX expression concurrent with PD-1, Tim-3, and CD244 in T cells from patients with non-Hodgkin lymphoma

AIM

To characterize immune suppression in lymphoma, thymocyte selection-associated high mobility group box protein (TOX) expression and co-expression with programmed cell death receptor-1 (PD-1), T cell immunoglobulin mucin-domain-containing-3 (Tim-3), and CD244 in CD3+, CD4+, CD8+, and regulatory T (Treg) cells from patients with lymphomas were analyzed.

METHODS

TOX expression and co-expression with PD-1, Tim-3, and CD244 in CD3+, CD4+, Treg, and CD8+ T cells were analyzed by multi-color fluorescent flow cytometry using peripheral blood (PB) from 13 newly diagnosed, untreated lymphoma patients, and 11 healthy individuals.

RESULTS

An increased percentage of TOX+ CD3+, CD4+, and CD8+ T cells was found in PB from patients with B cell non-Hodgkin's lymphoma (B-NHL) in comparison with healthy controls. Moreover, TOX+PD-1+ and TOX+Tim-3+ double-positive T cells increased among the CD3+, CD4+, and CD8+T cell populations in the B-NHL group. There was apparent heterogeneity in TOX expression and co-expression with PD-1, Tim-3, and CD244 in CD3+, CD4+, and CD8+ T cells in different lymphoma patients. In addition, the percentage of CD4+CD25+FoxP3+ T cells (Treg) among the CD3+ and CD4+ T cells significantly increased, and the number of TOX+ and TOX+PD-1+ Treg cells also significantly increased in the B-NHL group.

CONCLUSIONS

Higher expression of TOX concurrent with PD-1, Tim-3, and CD244 in T cells from patients with B-NHL may contribute to T cell exhaustion and impair their special anti-tumor T cell activity. TOX may be considered a potential target for reversing T cell exhaustion and improving T cell function in hematological malignancies.

Transcriptome-Based Co-Expression of BRD4 and PD-1/PD-L1 Predicts Poor Overall Survival in Patients With Acute Myeloid Leukemia

Positive response to PD-1/PD-L1 blockades was observed in the treatment of solid tumors. However, the clinical response to PD-1/PD-L1 blockade varied in patients with acute myeloid leukemia (AML). It is thought that there are factors other than PD-1 and PD-L1 that may affect the effect of immunotherapy. This study explored the impact of transcriptome-based co-expression of bromodomain containing 4 (BRD4) and PD-1/PD-L1 on the overall survival (OS) of patients with AML, in order to understand whether BRD4 would affect the effect of PD-1/PD-L1 blockades. Bone marrow samples from 59 AML patients in our clinical center and data of 176 patients from the Cancer Genome Atlas (TCGA) database were used for OS analysis and validation. It was found that increased expression of BRD4 was associated with poor OS in AML patients. Moreover, co-expression of BRD4 with PD-1 or PD-L1 was related to poor OS. The co-expression of BRD4 and PD-L1 was better than BRD4 and PD-1 for OS prediction. Furthermore, co-expression of BRD4 and PD-L1 was positively correlated with high tumor mutation burden, which contributed to poor OS in AML patients. Additionally, the co-expression of BRD4 and PD-L1 was associated with poor OS in non-acute promyelocytic leukemia patients with intermediate/high risk or under 60 years. Our results suggest that transcriptome-based co-expression of BRD4 and PD-L1 is a predictor for poor OS in AML patients, which might provide novel insight into designing combinational targeted therapy for AML.

Age-Related Immune Profile of the T Cell Receptor Repertoire, Thymic Recent Output Function, and miRNAs

Background

T cell immunity plays a central role in the body's defense system, including maintaining homeostasis and preventing tumorigenesis and viral infection. Immune system functions degenerate with age, leading to immune senescence. Physiologically, immune senescence is characterized by a decrease in T cell receptor diversity, naive T cell deficiency, and alterations in T cell immune-related miRNAs. However, little is known about the characteristics of T cell immunosenescence in Chinese individuals.

Results

A significant decrease in the miR-17, miR-92a, and miR-181a levels in PBMCs was detected with age. The miR-92a and miR-181a levels were upregulated in CBMCs when comparing healthy individuals to group I (0~9 years), whereas miR-17 was downregulated. The sjTREC level in PBMCs was negatively correlated with age, and a sharp decrease in sjTRECs was found between groups I and II (10~19 years). Twenty-four TCR Vβ subfamilies could be detected in most samples, and most displayed polyclonality, while skewed expression of the Vβ subfamilies as well as an increased oligoclonal tendency was found with age. Similarly, the frequencies of the TCR Vγ and Vδ subfamilies decreased with age, and the alteration in clonality appeared to be stable at different ages.

Conclusion

We made the novel observation of T cell immunosenescence with age in Chinese individuals, which may provide information for immune targets to enhance the T cell immune response in immunotherapy settings for elderly patients.

Higher TIGIT+CD226- γδ T cells in Patients with Acute Myeloid Leukemia

The diverse structural and functional heterogeneity of γδ T cells is related to their distinct role in cancer immunity. The different phenotypes of γδ T cells in patients with acute myeloid leukemia (AML) is far from clear. In particular, the expression pattern of co-inhibitory and co-stimulatory receptors on γδ T cells remains unknown. In this study, we analyzed the distribution of γδ T cell subsets by expression of the immune checkpoint co-inhibitor TIGIT (T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain) and its competing co-stimulatory receptor CD226 in AML patients of different clinical statuses (including de novo AML, AML in non-remission (NR), and AML in complete remission (CR)). Our data demonstrated an imbalanced distribution of TIGIT and CD226 on γδ T cells with a decrease in CD226⁺ γδ T cells and an increase in TIGIT⁺ γδ T cells in de novo AML patients, while TIGIT^-CD226⁺ γδ T cells were restored in AML patients who achieved CR after chemotherapy. Moreover, the patients who had higher TIGIT⁺CD226^- γδ T cells showed lower overall survival rate for non-M3 AML, which may be considered a novel prognostic immune biomarker. In conclusion, our study reveals for the first time that imbalance in the TIGIT/CD226 axis might be related to different clinical outcomes for AML patients.

ABBREVIATIONS

AML: acute myeloid leukemia; CR: complete remission; ICs: immune checkpoints; PD-1: programmed death-1; γδ T cells: gamma delta T cells; TCR: T cell receptor; MHC: major histocompatibility complex; TIGIT: T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain; NK: natural killer; PB: Peripheral blood; NR: non-remission; FAB: French-American-British; WHO: World Health Organization; HIs: healthy individuals; OS: overall survival.

Overexpression of TIGIT in NK and T Cells Contributes to Tumor Immune Escape in Myelodysplastic Syndromes

Objective

Targeting immune checkpoints, such as PD-1, represents a promising approach for cancer immunotherapy, achieving long-term disease remission rates in numerous types of cancer. T cell immunoglobulin and ITIM domain (TIGIT) is a checkpoint receptor associated with the antitumor roles of NK and T cells. Notably, the blockade of TIGIT has been revealed as a potential promising approach in cancer immunotherapy. However, the therapeutic potential of blocking TIGIT in myelodysplastic syndrome (MDS) remains unclear and further research is required to reveal their role.

Methods

Fresh peripheral blood (PB) and bone marrow (BM) were obtained from patients with MDS and healthy donors (HDs) at the Tianjin Medical University General Hospital between January 21 2018 and March 22 2019. The present study investigated the expression levels of TIGIT on NK and T cells using flow cytometry (FCM) and PCR. In addition, other checkpoint receptors, such as CD226 and PD-1, were also investigated. To determine the mechanisms of antitumor immunity, the functions of NK and T cells expressing TIGIT were determined.

Results

TIGIT was found to be highly expressed on NK and T cells of the PB, where it was involved in disease progression and the immune escape of MDS. The high expression levels of TIGIT were associated with decreased NK and T cell function, and significantly lower secretions of activation factors, such as CD107a, IFN-γ and TNF-α. Notably, blocking TIGIT enhanced the antitumor effects of NK and T cells.

Conclusion

The results of the present study suggested that targeting TIGIT alone or in combination with PD-1 may be a promising anticancer therapeutic strategy in MDS.

Regulation of PD-1 in T cells for cancer immunotherapy

Study of the molecular mechanisms underlying cancer immune escape is one of the core issues in immuno-oncology research. Cancer cells can evade T cell cytotoxicity by exploiting the upregulation of T cell inhibitory receptors on T cells and their ligands on cancer cells. These upregulated proteins include the inhibitory receptor programmed cell-death protein 1 (PD-1) and its ligand programmed cell death 1 ligand 1 (PD-L1), which can induce T cell exhaustion and reduce T cell activation. Characterizing PD-1 regulation will help to elucidate the molecular mechanisms underlying T cell exhaustion and improve cancer treatment. Recent studies have found that tumor cells regulate PD-1 during gene transcription, post-transcriptional regulation, and post-translational modification and influence the effects of the anticancer immune response by targeting PD-1. In this review,we summarize the mechanisms of PD-1 regulation in T cells.

Expression patterns of immune checkpoints in acute myeloid leukemia

Immunotherapy with immune checkpoint inhibitors (ICIs) for solid tumors had significantly improved overall survival. This type of therapy is still not available for acute myeloid leukemia (AML). One major issue is the lack of knowledge for the expression patterns of immune checkpoints (IC) in AML. In this study, we first explored the prognostic value of ICs for AML patients by analyzing RNA-seq and mutation data from 176 AML patients from the Cancer Genome Atlas (TCGA) database. We further validated the results of the database analysis by analyzing bone marrow (BM) samples from 62 patients with de novo AML. Both TCGA data and validation results indicated that high expression of PD-1, PD-L1, and PD-L2 was associated with poor overall survival (OS) in AML patients. In addition, increased co-expression of PD-1/CTLA-4 or PD-L2/CTLA-4 correlated with poor OS in AML patients (3-year OS: TGCA data 30% vs 0% and 20% vs 0%, validation group 57% vs 31% and 57% vs 33%, respectively) (P < 0.05). Moreover, co-expression of PD-1/PD-L1, PD-1/PD-L1/PD-L2, and PD-1/LAG-3 was found to correlate with poor OS in AML patients with FLT3^mut, RUNX1^mut, and TET2^mut, respectively. In conclusion, high expression of ICs in the BM leukemia cells of AML patients correlated with poor outcome. The co-expression patterns of PD-1/CTLA-4, PD-L2/CTLA-4, PD-1/PD-L1, PD-1/PD-L1/PD-L2, and PD-1/LAG-3 might be potential immune biomarkers for designing novel AML therapy.

Increased PD-1+Tim-3+ exhausted T cells in bone marrow may influence the clinical outcome of patients with AML

Background

Altered expression of T cell immune inhibitory receptors may result in immunosuppression and associate with the poor prognosis of leukemia patients in which the leukemic bone marrow (BM) microenvironment may contribute to such immunosuppression. We found higher numbers of programmed death-1 (PD-1) + exhausted T cells in peripheral blood (PB) from acute myeloid leukemia (AML) patients. To investigate the leukemic BM influence on immunosuppression, we further compared the distributions of PD-1 and T cell immunoglobulin mucin-3 (Tim-3) and the exhausted T cell phenotype in PB and BM from AML patients and characterized their relationship with clinical outcome.

Methods

PB and BM samples from 15 patients with newly diagnosed AML were collected and analyzed for the expression of PD-1, Tim-3, CD244, and CD57 on CD3+, CD4+, and CD8+ T cells by multicolor flow cytometry.

Results

The proportions of PD-1 + CD3+ and PD-1 + CD8+ T cells were significantly higher in BM compared with PB. Similarly, higher PD-1 + CD244 + CD3+ and PD-1 + CD244 + CD8+ T cells were found in BM, and an increased tendency for PD-1 + CD244 + CD4+ T cells was also detected in this group. In contrast, increased Tim-3 + CD4+/Tim-3 + CD244 + CD4+ T cells were predominant in BM compared with PB, but there was no statistically significant difference in Tim-3 + CD8+ T cells. Moreover, PD-1 and Tim-3 double-positive CD3+/CD4+/CD8+ T cells were significantly increased in the BM group. In addition, a higher proportion of PD-1 + Tim-3 + CD3+ T cells in the BM and PD-1 + Tim-3 + CD4+ T cells in PB was detected in non-complete remission (NCR) compared with complete remission (CR) patients after first-cycle chemotherapy.

Conclusions

Upregulation of PD-1 and Tim-3 and the exhausted phenotype of CD4+ and CD8+ T cells in the BM of AML patients may contribute to mediating the leukemic immunosuppressive microenvironment, and increased PD-1 + Tim-3+ CD8+ T cells may be related to T cell dysfunction in AML, which may influence clinical outcome.

Increasing Tim-3+CD244+, Tim-3+CD57+, and Tim-3+PD-1+ T cells in patients with acute myeloid leukemia

AIM

To characterize the distribution of T cell immunoglobulin mucin-domain-containing-3 (Tim-3) within the exhausted T cells in patients with newly diagnosed acute myeloid leukemia (AML) and AML in complete remission.

METHODS

Tim-3 expression and coexpression with PD-1, CD244, and CD57 in CD3+, CD4+, and CD8+T cells were analyzed by multicolored fluorescent flow cytometry in peripheral blood from 28 newly diagnosed, untreated AML patient and 12 cases with AML in complete remission, 23 healthy individuals served as control.

RESULTS

Increasing Tim-3+CD244+ and Tim-3+CD57+ in CD3+, CD4+, and CD8+ T cells were found in AML and AML-CR groups in comparison with healthy controls. Similarly, increasing Tim-3 coexpression PD-1+ CD3+/CD4+/CD8+ T cells were found in AML group. A high tendency of PD-1+Tim-3+CD3+/CD4+/CD8+ T cells was detected in the AML-M4 subtype group followed by the M2 group, and a low tendency was found in the M3 group. Moreover, Tim-3+CD244+CD8+ T cells were found to be significantly higher in the M4 than that in M3 group. Dynamic changes of Tim-3+ T cells in AML patients who achieved CR after chemotherapy at different time points showed that Tim-3+ T cell subsets were evidently decreased; however, they remained at a higher level in most AML-CR patients.

CONCLUSION

We made a novel observation on distribution of Tim-3+CD244+, Tim-3+CD57+, and Tim-3+PD-1+ T cells in patients with AML. Chemotherapy is incapable of resolving immunosuppression in some cases with AML in CR status.

Higher frequency of the CTLA-4+ LAG-3+ T-cell subset in patients with newly diagnosed acute myeloid leukemia

AIM

Immune suppression based on alternative regulation of immune checkpoint proteins, for example, programmed cell death receptor-1 (PD-1) and cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), which results in T-cell exhaustion, contributes to cancer development and progression. In this study, we sought to characterize the distribution of CTLA-4 and T-cell lymphocyte activation gene-3 (LAG-3) expression on exhausted T cells in different T-cell subsets from patients with acute myeloid leukemia (AML).

METHODS

The coexpression of CTLA-4 and LAG-3 on exhausted CD244⁺ and CD57⁺ T cells from the CD3⁺ , CD4⁺ , and CD8⁺ T-cell subsets in peripheral blood from 12 patients with newly diagnosed AML was analyzed by multicolor flow cytometry assay.

RESULTS

A significantly higher percentage of CTLA-4⁺ CD3⁺ , CD4⁺ and CD8⁺ T cells was found in patients with AML. In addition, higher numbers of both CTLA-4⁺ CD244+ and CTLA-4⁺ CD57⁺ CD3⁺ T cells were detected. Interestingly, the increased CTLA-4⁺ CD244⁺ T cells were predominantly CD4⁺ T cells. In contrast, the increased CTLA-4⁺ CD57⁺ T cells primarily consisted of the CD8⁺ T-cell subset. A high proportion of LAG-3⁺ T cells was found in only a few cases with AML; however, a significantly higher proportion of coexpression of CTLA-4 and LAG-3 in the CD3⁺ and CD8⁺ T-cell subsets was detected.

CONCLUSION

We for the first time observed higher CTLA-4⁺ CD244⁺ CD4⁺ , CTLA-4⁺ CD57⁺ CD8⁺ , CTLA-4⁺ LAG-3⁺ CD3⁺ and CTLA-4⁺ LAG-3⁺ CD8⁺ T cells in patients with AML, whereas the upregulated expression of LAG-3 on T cells was only found in a subset of the cases. These data may provide further information by complementing the heterogeneity of immune checkpoints expression in AML.