The Role of T Cell Immunotherapy in Acute Myeloid Leukemia

A review of common immunotherapy and nano immunotherapy for acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly aggressive hematological malignancy. Traditional chemotherapy methods not only bring serious side effects, but also lead to high recurrence rate and drug resistance in some patients. However, as an emerging therapeutic strategy, immunotherapy has shown great potential in the field of AML treatment in recent years. At present, common immunotherapy methods for AML include monoclonal antibodies, CAR-T cell therapy, and immune checkpoint inhibitors. With the deepening of research and technological progress, especially the application of nanotechnology in medicine, new immunotherapy is expected to become one of the important means for the treatment of acute myeloid leukemia in the future.

Immunoediting in acute myeloid leukemia: Reappraising T cell exhaustion and the aberrant antigen processing machinery in leukemogenesis

Acute myeloid leukemia (AML) establishes an immunosuppressive microenvironment that favors leukemic proliferation. The immune-suppressive cytokines altered antigen processing, and presentation collectively assist AML cells in escaping cytotoxic T-cell surveillance. These CD8+ T cell dysfunction features are emerging therapeutic targets in relapsed/refractory AML patients. Besides, CD8+ T cell exhaustion is a hotspot in recent clinical oncology studies, but its pathophysiology has yet to be elucidated in AML. In this review, we summarize high-quality original studies encompassing the phenotypic and genomic characteristics of T cell exhaustion events in the leukemia progression, emphasize the surface immuno-peptidome that dynamically tunes the fate of T cells to function or dysfunction states, and revisit the biochemical and biophysical properties of type 1 MHC antigen processing mechanism (APM) that pivots in the phenomenon of leukemia antigen dampening.

Participation of T cells in generating immune protection against cancers

T cells are essential to the immune system's reaction. The major job of the immune system is to identify and get rid of any abnormal or malignant cells in the body. White blood cells called T cells coordinate and carry out immunological responses, including identifying and eliminating cancer cells. It mostly consists of two types called helper T-cells and cytotoxic T-cells. Together, they create an efficient reaction against cancer. Both the primary T cell subtype - CD4+ and CD8+ Tcells have specific role to play in our immune system.CD4+ T cells are limited to MHC-II molecules and acts as helper cell by activating and enhancing other immune cells. On the other side CD8+ T cells are called the killer cells as they eradicate the abnormal and contaminated cells and are limited to MHC-I molecules. The malignant cells are destroyed when cytotoxic T cells come into direct contact with them. This happens via number of processes, including TCR recognition, the release of cytotoxic chemicals, and finally the activation of the immune system. T cell receptors on the surface of cytotoxic T cells allow them to identify tumour cells and these T cells release harmful chemicals like perforins and granzymes when they connect to malignant cells. T-cells that have been stimulated release cytokines such as gamma interferon. T-cells can also acquire memory responses that improve their capacity for recognition and response. Helper T-cells contribute to the development of an immune response. It entails coordination and activation as well as the enlistment of additional immune cells, including macrophages and natural killer cells, to assist in the eradication of cancer cells. Despite the fact that the cancer frequently creates defence systems to circumvent their immune response. Together, these activities support the immune surveillance and T-cell-mediated regulation of cancer cells. Treatments like chemotherapy, radiation, and surgery are main ways to treat cancer but immunotherapy has been emerging since last few decades. These immune specific treatments have shown huge positive result. CAR T cell therapy is a promising weapon to fight again blood cancer and it works by focusing on our immune system to fight and eliminate cancer.

DOGMA-seq and multimodal, single-cell analysis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a complex cancer, yet advances in recent years from integrated genomics methods have helped improve diagnosis, treatment, and means of patient stratification. A recent example of a powerful, multimodal method is DOGMA-seq, which can measure chromatin accessibility, gene expression, and cell-surface protein levels from the same individual cell simultaneously. Previous bimodal single-cell techniques, such as CITE-seq (Cellular indexing of transcriptomes and epitopes), have only permitted the transcriptome and cell-surface protein expression measurement. DOGMA-seq, however, builds on this foundation and has implications for examining epigenomic, transcriptomic, and proteomic interactions between various cell types. This technique has the potential to be particularly useful in the study of cancers such as AML. This is because the cellular mechanisms that drive AML are rather heterogeneous and require a more complete understanding of the interplay between the genetic mutations, disruptions in RNA transcription and translation, and surface protein expression that cause these cancers to develop and evolve. This technique will hopefully contribute to a more clear and complete understanding of the growth and progression of complex cancers.

Immune-dysregulation harnessing in myeloid neoplasms

Myeloid malignancies arise in bone marrow microenvironments and shape these microenvironments in favor of malignant development. Immune suppression is one of the most important stages in myeloid leukemia progression. Leukemic clone expansion and immune dysregulation occur simultaneously in bone marrow microenvironments. Complex interactions emerge between normal immune system elements and leukemic clones in the bone marrow. In recent years, researchers have identified several of these pathological interactions. For instance, recent works shows that the secretion of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), from bone marrow stromal cells contributes to immune dysregulation and the selective proliferation of JAK2V617F+ clones in myeloproliferative neoplasms. Moreover, inflammasome activation and sterile inflammation result in inflamed microenvironments and the development of myelodysplastic syndromes. Additional immune dysregulations, such as exhaustion of T and NK cells, an increase in regulatory T cells, and impairments in antigen presentation are common findings in myeloid malignancies. In this review, we discuss the role of altered bone marrow microenvironments in the induction of immune dysregulations that accompany myeloid malignancies. We also consider both current and novel therapeutic strategies to restore normal immune system function in the context of myeloid malignancies.

The Immune Resistance Signature of Acute Myeloid Leukemia and Current Immunotherapy Strategies

Acute myeloid leukemia (AML) is a complex hematopoietic clonal disorder with limited curative options beyond stem cell transplantation. The success of transplant is intimately linked with the graft versus leukemia effect from the alloreactive donor immune cells including, T and NK cells. The immune system plays a dynamic role in leukemia survival and resistance. Despite our growing understanding of the immune microenvironment, responses to immune-based therapies differ greatly between patients. Herein, we review the biology of immune evasion mechanisms in AML, discuss the current landscape of immunotherapeutic strategies, and discuss the implications of therapeutic targets. This review focuses on T and NK cell-based therapy, including modified and non-modified NK cells, CAR-T and CAR-NK cells, antibodies, and checkpoint blockades. Understanding the complex interchange between immune tolerance and the emergence of tumor resistance will improve patient outcomes.

Higher TIGIT+ γδ TCM cells may predict poor prognosis in younger adult patients with non-acute promyelocytic AML

Introduction

γδ T cells recognize and exert cytotoxicity against tumor cells. They are also considered potential immune cells for immunotherapy. Our previous study revealed that the altered expression of immune checkpoint T-cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) on γδ T cells may result in immunosuppression and is possibly associated with a poor overall survival in acute myeloid leukemia (AML). However, whether γδ T-cell memory subsets are predominantly involved and whether they have a relationship with clinical outcomes in patients with AML under the age of 65 remain unclear.

Methods

In this study, we developed a multicolor flow cytometry-based assay to monitor the frequency and distribution of γδ T-cell subsets, including central memory γδ T cells (TCM γδ), effector memory γδ T cells (TEM γδ), and TEM expressing CD45RA (TEMRA γδ), in peripheral blood from 30 young (≤65 years old) patients with newly diagnosed non-acute promyelocytic leukemia (also known as M3) AML (AMLy-DN), 14 young patients with AML in complete remission (AMLy-CR), and 30 healthy individuals (HIs).

Results

Compared with HIs, patients with AMLy-DN exhibited a significantly higher differentiation of γδ T cells, which was characterized by decreased TCM γδ cells and increased TEMRA γδ cells. A generally higher TIGIT expression was observed in γδ T cells and relative subsets in patients with AMLy-DN, which was partially recovered in patients with AMLy-CR. Furthermore, 17 paired bone marrow from patients with AMLy-DN contained higher percentages of γδ and TIGIT+ γδ T cells and a lower percentage of TCM γδ T cells. Multivariate logistic regression analyses revealed the association of high percentage of TIGIT+ TCM γδ T cells with an increased risk of poor induction chemotherapy response.

Conclusions

In this study, we investigated the distribution of γδ T cells and their memory subsets in patients with non-M3 AML and suggested TIGIT+ TCM γδ T cells as potential predictive markers of induction chemotherapy response.

Chimeric antigen receptor (CAR) modified T Cells in acute myeloid leukemia: limitations and expectations

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy with a poor prognosis despite the advent of novel therapies. Consequently, a major need exists for new therapeutic options, particularly for patients with relapsed/refractory (R/R) AML. In recent years, it has been possible to individualize the treatment of a subgroup of patients, particularly with the emergence of multiple targeted therapies. Nonetheless, a considerable number of patients remain without therapeutic options, and overall prognosis remains poor because of a high rate of disease relapse. In this sense, cellular therapies, especially chimeric antigen receptor (CAR)-T cell therapy, have dramatically shifted the therapeutic options for other hematologic malignancies, such as diffuse large B cell lymphoma and acute lymphoblastic leukemia. In contrast, effectively treating AML with CAR-based immunotherapy poses major biological and clinical challenges, most of them derived from the unmet need to identify target antigens with expression restricted to the AML blast without compromising the viability of the normal hematopoietic stem cell counterpart. Although those limitations have hampered CAR-T cell therapy translation to the clinic, there are several clinical trials where target antigens, such as CD123, CLL-1 or CD33 are being used to treat AML patients showing promising results. Moreover, there are continuing efforts to enhance the specificity and efficacy of CAR-T cell therapy in AML. These endeavors encompass the exploration of novel avenues, including the development of dual CAR-T cells and next-generation CAR-T cells, as well as the utilization of gene editing tools to mitigate off-tumor toxicities. In this review, we will summarize the ongoing clinical studies and the early clinical results reported with CAR-T cells in AML, as well as highlight CAR-T cell limitations and the most recent approaches to overcome these barriers. We will also discuss how and when CAR-T cells should be used in the context of AML.

Evaluation of the safety and efficiency of cytotoxic T cell therapy sensitized by tumor antigens original from T-ALL-iPSC in vivo

Background

Since RNA sequencing has shown that induced pluripotent stem cells (iPSCs) share a common antigen profile with tumor cells, cancer vaccines that focus on iPSCs have made promising progress in recent years. Previously, we showed that iPSCs derived from leukemic cells of patients with primary T cell acute lymphoblastic leukemia (T-ALL) have a gene expression profile similar to that of T-ALL cell lines.

Methods

Mice with T-ALL were treated with dendritic and T (DC-T) cells loaded with intact and complete antigens from T-ALL-derived iPSCs (T-ALL-iPSCs). We evaluated the safety and antitumor efficiency of autologous tumor-derived iPSC antigens by flow cytometry, cytokine release assay, acute toxicity experiments, long-term toxicity experiments, and other methods.

Results

Our results indicate that complete tumor antigens from T-ALL-iPSCs could inhibit the growth of inoculated tumors in immunocompromised mice without causing acute and long-term toxicity.

Conclusion

T-ALL-iPSC-based treatment is safe and can be used as a potential strategy for leukemia immunotherapy.

Immunotherapies of acute myeloid leukemia: Rationale, clinical evidence and perspective

Acute myeloid leukemia (AML) is a prevalent hematological malignancy that exhibits a wide array of molecular abnormalities. Although traditional treatment modalities such as chemotherapy and allogeneic stem cell transplantation (HSCT) have become standard therapeutic approaches, a considerable number of patients continue to face relapse and encounter a bleak prognosis. The emergence of immune escape, immunosuppression, minimal residual disease (MRD), and other contributing factors collectively contribute to this challenge. Recent research has increasingly highlighted the notable distinctions between AML tumor microenvironments and those of healthy individuals. In order to investigate the potential therapeutic mechanisms, this study examines the intricate transformations occurring between leukemic cells and their surrounding cells within the tumor microenvironment (TME) of AML. This review classifies immunotherapies into four distinct categories: cancer vaccines, immune checkpoint inhibitors (ICIs), antibody-based immunotherapies, and adoptive T-cell therapies. The results of numerous clinical trials strongly indicate that the identification of optimal combinations of novel agents, either in conjunction with each other or with chemotherapy, represents a crucial advancement in this field. In this review, we aim to explore the current and emerging immunotherapeutic methodologies applicable to AML patients, identify promising targets, and emphasize the crucial requirement to augment patient outcomes. The application of these strategies presents substantial therapeutic prospects within the realm of precision medicine for AML, encompassing the potential to ameliorate patient outcomes.

C-5401331 identified as a novel T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) inhibitor to control acute myeloid leukemia (AML) cell proliferation

T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) is a checkpoint protein expressed in exhausted T-cells during cancer scenarios. This exhaustion may end in T-cell effector dysfunction, resulting in suboptimal control of cancers like acute myeloid leukemia (AML). Use of immune checkpoint inhibitors (ICIs) to block checkpoint receptors such as Tim-3 is an emerging, revolutionary concept in the immuno-oncology therapeutic arena; however, ICIs are not effective on myeloid malignancies. Here, a multifaceted approach is utilized to identify novel compounds that target and inhibit Tim-3 with improved efficacy. High-throughput virtual screening of the ChemBridge small molecule library and molecular dynamics simulation yielded a lead molecule C-5401331 predicted to bind with high affinity and inhibit the activity of Tim-3. In vitro evaluations demonstrated the compound to have anti-proliferative effects on Tim-3-positive populations of THP-1 and HC-5401331 AML cells, inducing early and late phase apoptosis. With further development, the lead molecule identified in this work has potential to aid the natural "gatekeeper" functions of the body in immunocompromised AML cancer patients by successfully hampering the binding of Tim-3 to T-cells.

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.

Spatiotemporal evolution of AML immune microenvironment remodeling and RNF149-driven drug resistance through single-cell multidimensional analysis

BACKGROUND

The composition of the bone marrow immune microenvironment in patients with acute myeloid leukaemia (AML) was analysed by single-cell sequencing and the evolutionary role of different subpopulations of T cells in the development of AML and in driving drug resistance was explored in conjunction with E3 ubiquitin ligase-related genes.

METHODS

To elucidate the mechanisms underlying AML-NR and Ara-C resistance, we analyzed the bone marrow immune microenvironment of AML patients by integrating multiple single-cell RNA sequencing datasets. When compared to the AML disease remission (AML-CR) cohort, AML-NR displayed distinct cellular interactions and alterations in the ratios of CD4+T, Treg, and CD8+T cell populations.

RESULTS

Our findings indicate that the E3 ubiquitin ligase RNF149 accelerates AML progression, modifies the AML immune milieu, triggers CD8+T cell dysfunction, and influences the transformation of CD8+ Navie.T cells to CD8+TExh, culminating in diminished AML responsiveness to chemotherapeutic agents. Experiments both in vivo and in vitro revealed RNF149's role in enhancing AML drug-resistant cell line proliferation and in apoptotic inhibition, fostering resistance to Ara-C.

CONCLUSION

In essence, the immune microenvironments of AML-CR and AML-NR diverge considerably, spotlighting RNF149's tumorigenic function in AML and cementing its status as a potential prognostic indicator and innovative therapeutic avenue for countering AML resistance.

Divergent CD4+ T-cell profiles are associated with anti-HLA alloimmunization status in platelet-transfused AML patients

Introduction

Acute myeloid leukemia (AML) is one of the commonest hematologic disorders. Due to the high frequency of disease- or treatment-related thrombocytopenia, AML requires treatment with multiple platelet transfusions, which can trigger a humoral response directed against platelets. Some, but not all, AML patients develop an anti-HLA immune response after multiple transfusions. We therefore hypothesized that different immune activation profiles might be associated with anti-HLA alloimmunization status.

Methods

We tested this hypothesis, by analyzing CD4+ T lymphocyte (TL) subsets and their immune control molecules in flow cytometry and single-cell multi-omics.

Results

A comparison of immunological status between anti-HLA alloimmunized and non-alloimmunized AML patients identified differences in the phenotype and function of CD4+ TLs. CD4+ TLs from alloimmunized patients displayed features of immune activation, with higher levels of CD40 and OX40 than the cells of healthy donors. However, the most notable differences were observed in non-alloimmunized patients. These patients had lower levels of CD40 and OX40 than alloimmunized patients and higher levels of PD1. Moreover, the Treg compartment of non-alloimmunized patients was larger and more functional than that in alloimmunized patients. These results were supported by a multi-omics analysis of immune response molecules in conventional CD4+ TLs, Tfh circulating cells, and Tregs.

Discussion

Our results thus reveal divergent CD4+ TL characteristics correlated with anti-HLA alloimmunization status in transfused AML patients. These differences, characterizing CD4+ TLs independently of any specific antigen, should be taken into account when considering the immune responses of patients to infections, vaccinations, or transplantations.

FIBP is a prognostic biomarker and correlated with clinicalpathological characteristics and immune infiltrates in acute myeloid leukemia

Acute myeloid leukemia (AML) is one of the most common hematological malignancy that has a high recurrence rate. FIBP was reported to be highly expressed in multiple tumor types. However, its expression and role in acute myeloid leukemia remains largely unknown. The aim of this study was to clarify the role and value of FIBP in the diagnosis and prognosis, and to analyze its correlation with immune infiltration in acute myeloid leukemia by The Cancer Genome Atlas (TCGA) dataset. FIBP was highly expressed in AML samples compared to normal samples. The differentially expressed genes were identified between high and low expression of FIBP. The high FIBP expression group had poorer overall survival. FIBP was closely correlated with CD4, IL-10 and IL-2. The enrichment analysis indicated DEGs were mainly related to leukocyte migration, leukocyte cell-cell adhesion, myeloid leukocyte differentiation, endothelial cell proliferation and T cell tolerance induction. FIBP expression has significant correlation with infiltrating levels of various immune cells. FIBP could be a potential targeted therapy and prognostic biomarker associated with immune infiltrates for AML.

Does Cytokine-Release Syndrome Induced by CAR T-Cell Treatment Have an Impact on the Pharmacokinetics of Meropenem and Piperacillin/Tazobactam in Patients with Hematological Malignancies? Findings from an Observational Case-Control Study

Chimeric antigen receptor (CAR) T-cell therapy is a promising approach for some relapse/refractory hematological B-cell malignancies; however, in most patients, cytokine release syndrome (CRS) may occur. CRS is associated with acute kidney injury (AKI) that may affect the pharmacokinetics of some beta-lactams. The aim of this study was to assess whether the pharmacokinetics of meropenem and piperacillin may be affected by CAR T-cell treatment. The study included CAR T-cell treated patients (cases) and oncohematological patients (controls), who were administered 24-h continuous infusion (CI) meropenem or piperacillin/tazobactam, optimized by therapeutic drug monitoring, over a 2-year period. Patient data were retrospectively retrieved and matched on a 1:2 ratio. Beta-lactam clearance (CL) was calculated as CL = daily dose/infusion rate. A total of 38 cases (of whom 14 and 24 were treated with meropenem and piperacillin/tazobactam, respectively) was matched with 76 controls. CRS occurred in 85.7% (12/14) and 95.8% (23/24) of patients treated with meropenem and piperacillin/tazobactam, respectively. CRS-induced AKI was observed in only 1 patient. CL did not differ between cases and controls for both meropenem (11.1 vs. 11.7 L/h, p = 0.835) and piperacillin (14.0 vs. 10.4 L/h, p = 0.074). Our findings suggest that 24-h CI meropenem and piperacillin dosages should not be reduced a priori in CAR T-cell patients experiencing CRS.

A potential area of use for immune checkpoint inhibitors: Targeting bone marrow microenvironment in acute myeloid leukemia

Acute myeloid leukemia (AML) arises from the cells of myeloid lineage and is the most frequent leukemia type in adulthood accounting for about 80% of all cases. The most common treatment strategy for the treatment of AML includes chemotherapy, in rare cases radiotherapy and stem cell and bone marrow transplantation are considered. Immune checkpoint proteins involve in the negative regulation of immune cells, leading to an escape from immune surveillance, in turn, causing failure of tumor cell elimination. Immune checkpoint inhibitors (ICIs) target the negative regulation of the immune cells and support the immune system in terms of anti-tumor immunity. Bone marrow microenvironment (BMM) bears various blood cell lineages and the interactions between these lineages and the noncellular components of BMM are considered important for AML development and progression. Administration of ICIs for the AML treatment may be a promising option by regulating BMM. In this review, we summarize the current treatment options in AML treatment and discuss the possible application of ICIs in AML treatment from the perspective of the regulation of BMM.

CD86 Is Associated with Immune Infiltration and Immunotherapy Signatures in AML and Promotes Its Progression

Background

Cluster of differentiation 86 (CD86), also known as B7-2, is a molecule expressed on antigen-presenting cells that provides the costimulatory signals required for T cell activation and survival. CD86 binds to two ligands on the surface of T cells: the antigen CD28 and cytotoxic T lymphocyte-associated protein 4 (CTLA-4). By binding to CD28, CD86-together with CD80-promotes the participation of T cells in the antigen presentation process. However, the interrelationships among CD86, immunotherapy, and immune infiltration in acute myeloid leukemia (AML) are unclear.

Methods

The immunological effects of CD86 in various cancers (including on chemokines, immunostimulators, MHC, and receptors) were evaluated through a pan-cancer analysis using TCGA and GEO databases. The relationship between CD86 expression and mononucleotide variation, gene copy number variation, methylation, immune checkpoint blockers (ICBs), and T-cell inflammation score in AML was subsequently examined. ESTIMATE and limma packages were used to identify genes at the intersection of CD86 with StromalScore and ImmuneScore. Subsequently, GO/KEGG and PPI network analyses were performed. The immune risk score (IRS) model was constructed, and the validation set was used for verification. The predictive value was compared with the TIDE score.

Results

CD86 was overexpressed in many cancers, and its overexpression was associated with a poor prognosis. CD86 expression was positively correlated with the expression of CTLA4, PDCD1LG2, IDO1, HAVCR2, and other genes and negatively correlated with CD86 methylation. The expression of CD86 in AML cell lines was detected by QRT-PCR and Western blot, and the results showed that CD86 was overexpressed in AML cell lines. Immune infiltration assays showed that CD86 expression was positively correlated with CD8 T cell, Dendritic cell, macrophage, NK cell, and Th1_cell and also with immune examination site, immune regulation, immunotherapy response, and TIICs. ssGSEA showed that CD86 was enriched in immune-related pathways, and CD86 expression was correlated with mutations in the genes RB1, ERBB2, and FANCC, which are associated with responses to radiotherapy and chemotherapy. The IRS score performed better than the TIDE website score.

Conclusion

CD86 appears to participate in immune invasion in AML and is an important player in the tumor microenvironment in this malignancy. At the same time, the IRS score developed by us has a good effect and may provide some support for the diagnosis of AML. Thus, CD86 may serve as a potential target for AML immunotherapy.

Repair of Limb Ischemia Is Dependent on Hematopoietic Stem Cell Specific-SHP-1 Regulation of TGF-β1

BACKGROUND

Hematopoietic stem cell (HSC) therapy has shown promise for tissue regeneration after ischemia. Therefore, there is a need to understand mechanisms underlying endogenous HSCs activation in response to ischemic stress and coordination of angiogenesis and repair. SHP-1 plays important roles in HSC quiescence and differentiation by regulation of TGF-β1 signaling. TGF-β1 promotes angiogenesis by stimulating stem cells to secrete growth factors to initiate the formation of blood vessels and later aid in their maturation. We propose that SHP-1 responds to ischemia stress in HSC and progenitor cells (HSPC) via regulation of TGF-β1.

METHODS

A mouse hind limb ischemia model was used. Local blood perfusion in the limbs was determined using laser doppler perfusion imaging. The number of positive blood vessels per square millimeter, as well as blood vessel diameter (μm) and area (μm²), were calculated. Hematopoietic cells were analyzed using flow cytometry. The bone marrow transplantation assay was performed to measure HSC reconstitution.

RESULTS

After femoral artery ligation, TGF-β1 was initially decreased in the bone marrow by day 3 of ischemia, followed by an increase on day 7. This pattern was opposite to that in the peripheral blood, which is concordant with the response of HSC to ischemic stress. In contrast, SHP-1 deficiency in HSC is associated with irreversible activation of HSPCs in the bone marrow and increased circulating HSPCs in peripheral blood following limb ischemia. In addition, there was augmented auto-induction of TGF-β1 and sustained inactivation of SHP-1-Smad2 signaling, which impacted TGF-β1 expression in HSPCs in circulation. Importantly, restoration of normal T GF-β1 oscillations helped in the recovery of limb repair and function.

CONCLUSIONS

HSPC-SHP-1-mediated regulation of TGF-β1 in both bone marrow and peripheral blood is required for a normal response to ischemic stress.

Combined flow cytometry natural killer immunophenotyping and KIR/HLA-C genotyping reveal remarkable differences in acute myeloid leukemia patients, but suggest an overall impairment of the natural killer response

Introduction

Natural killer (NK) cells are key anti-tumor effectors of the innate immunity. Phenotypic differences allow us to discriminate in between three functional stages of maturation, named immature, mature and hypermature that are distinctive in terms of receptor expression, cytokine secretion, cytotoxic properties and organ trafficking. NKs display an impressive repertoire of highly polymorphic germline encoded receptors that can be either activating, triggering the effector's function, or inhibitory, limiting the immune response. In our study, we have investigated peripheral blood NK cells of acute myeloid leukemia (AML) patients.

Methods

The Killer Immunoglobulin-like receptors (KIRs) and the HLA-C genotypes were assessed, as HLA-C molecules are cognate antigens for inhibitory KIRs.

Results

The AA mainly inhibitory KIR haplotype was found in a higher proportion in AML, while a striking low frequency of the 2DS3 characterized the mainly activating Bx haplotype. Flow cytometry immunophenotyping evidenced a lower overall count of NK cells in AML versus healthy controls, with lower percentages of the immature and mature subpopulations, but with a markedly increase of the hypermature NKs. The analysis of the KIR2DL1, KIR2DL2, KIR2DL3, KIR3DL1, and NKG2A inhibitory receptors surface expression revealed a remarkable heterogeneity. However, an overall trend for a higher expression in AML patients could be noticed in all maturation subpopulations. Some of the AML patients with complex karyotypes or displaying a FLT3 gene mutation proved to be extreme outliers in terms of NK cells percentages or inhibitory receptors expression.

Discussion

We conclude that while the genetic background investigation in AML offers important pieces of information regarding susceptibility to disease or prognosis, it is flow cytometry that is able to offer details of finesse in terms of NK numbers and phenotypes, necessary for an adequate individual evaluation of these patients.

FLT3LG and IFITM3P6 consolidate T cell activity in the bone marrow microenvironment and are prognostic factors in acute myelocytic leukemia

Acute myelocytic leukemia (AML) is a malignancy of the stem cell precursors of the myeloid lineage. CD4+ and CD8+ T cells play pivotal roles in influencing AML progression but are functionally suppressed in the bone marrow microenvironment. We aimed to find hub genes related to T cell exhaustion and suppression, thereby providing evidence for immunotherapy. In this study, gene transcriptome expression data from TCGA and TARGET databases were utilized to find key genes. Firstly, CIBERSORT immune cell infiltration algorithm and WGCNA method were used to identify CD4+ and CD8+ T cells-related genes. Univariate and multivariate cox regression analyses were then introduced to construct the overall survival prognosis model and included hub genes. The ESTIMATE and ssGSEA scoring methods were used to analyze the correlation between the hub genes and immune activity. Single-cell transcriptome analysis was applied to detect the immune cells expressing hub genes, hence, to detect exact mechanisms. Consequently, FLT3LG and IFITM3P6 were determined to be positively correlated with patients’ overall survival and microenvironment immune activity. Further study suggested FLT3-FLT3LG and IFITM3P6-miR-6748-3p-CBX7 signaling axes were involved in CD4+ and CD8+ T cells activation. This may be one of the mechanisms of T cells suppression in AML.