Upregulation of CD200 is associated with Foxp3+ regulatory T cell expansion and disease progression in acute myeloid leukemia

Exploiting the CD200-CD200R immune checkpoint axis in multiple myeloma to enhance CAR T-cell therapy

ABSTRACT

Patients with multiple myeloma (MM) treated with B-cell maturation antigen (BCMA)-specific chimeric antigen receptor (CAR) T cells usually relapse with BCMA+ disease, indicative of CAR T-cell suppression. CD200 is an immune checkpoint that is overexpressed on aberrant plasma cells (aPCs) in MM and is an independent negative prognostic factor for survival. However, CD200 is not present on MM cell lines, a potential limitation of current preclinical models. We engineered MM cell lines to express CD200 at levels equivalent to those found on aPCs in MM and show that these are sufficient to suppress clinical-stage CAR T-cells targeting BCMA or the Tn glycoform of mucin 1 (TnMUC1), costimulated by 4-1BB and CD2, respectively. To prevent CD200-mediated suppression of CAR T cells, we compared CRISPR-Cas9-mediated knockout of the CD200 receptor (CD200RKO), to coexpression of versions of the CD200 receptor that were nonsignaling, that is, dominant negative (CD200RDN), or that leveraged the CD200 signal to provide CD28 costimulation (CD200R-CD28 switch). We found that the CD200R-CD28 switch potently enhanced the polyfunctionality of CAR T cells, and improved cytotoxicity, proliferative capacity, CAR T-cell metabolism, and performance in a chronic antigen exposure assay. CD200RDN provided modest benefits, but surprisingly, the CD200RKO was detrimental to CAR T-cell activity, adversely affecting CAR T-cell metabolism. These patterns held up in murine xenograft models of plasmacytoma, and disseminated bone marrow predominant disease. Our findings underscore the importance of CD200-mediated immune suppression in CAR T-cell therapy of MM, and highlight a promising approach to enhance such therapies by leveraging CD200 expression on aPCs to provide costimulation via a CD200R-CD28 switch.

Immunotherapy in Acute Myeloid Leukemia: A Literature Review of Emerging Strategies

In the last twenty years, we have witnessed a paradigm shift in the treatment and prognosis of acute myeloid leukemia (AML), thanks to the introduction of new efficient drugs or approaches to refine old therapies, such as Gemtuzumab Ozogamicin, CPX 3-5-1, hypomethylating agents, and Venetoclax, the optimization of conditioning regimens in allogeneic hematopoietic stem cell transplantation and the improvement of supportive care. However, the long-term survival of non-M3 and non-core binding factor-AML is still dismal. For this reason, the expectations for the recently developed immunotherapies, such as antibody-based therapy, checkpoint inhibitors, and chimeric antigen receptor strategies, successfully tested in other hematologic malignancies, were very high. The inherent characteristics of AML blasts hampered the development of these treatments, and the path of immunotherapy in AML has been bumpy. Herein, we provide a detailed review of potential antigenic targets, available data from pre-clinical and clinical trials, and future directions of immunotherapies in AML.

Emerging Immune Checkpoint Molecules on Cancer Cells: CD24 and CD200

Cancer immunotherapy strategies are based on the utilization of immune checkpoint inhibitors to instigate an antitumor immune response. The efficacy of immune checkpoint blockade, directed at adaptive immune checkpoints, has been demonstrated in select cancer types. However, only a limited subset of patients has exhibited definitive outcomes characterized by a sustained response after discontinuation of therapy. Recent investigations have highlighted the significance of immune checkpoint molecules that are overexpressed in cancer cells and inhibit myeloid lineage immune cells within a tumor microenvironment. These checkpoints are identified as potential targets for anticancer immune responses. Notably, the immune checkpoint molecules CD24 and CD200 have garnered attention owing to their involvement in tumor immune evasion. CD24 and CD200 are overexpressed across diverse cancer types and serve as signaling checkpoints by engaging their respective receptors, Siglec-10 and CD200 receptor, which are expressed on tumor-associated myeloid cells. In this review, we summarized and discussed the latest advancements and insights into CD24 and CD200 as emergent immune checkpoint moieties, further delving into their therapeutic potentials for cancer treatment.

The role of bone marrow microenvironment (BMM) cells in acute myeloid leukemia (AML) progression: immune checkpoints, metabolic checkpoints, and signaling pathways

Acute myeloid leukemia (AML) comprises a multifarious and heterogeneous array of illnesses characterized by the anomalous proliferation of myeloid cells in the bone marrow microenvironment (BMM). The BMM plays a pivotal role in promoting AML progression, angiogenesis, and metastasis. The immune checkpoints (ICs) and metabolic processes are the key players in this process. In this review, we delineate the metabolic and immune checkpoint characteristics of the AML BMM, with a focus on the roles of BMM cells e.g. tumor-associated macrophages, natural killer cells, dendritic cells, metabolic profiles and related signaling pathways. We also discuss the signaling pathways stimulated in AML cells by BMM factors that lead to AML progression. We then delve into the roles of immune checkpoints in AML angiogenesis, metastasis, and cell proliferation, including co-stimulatory and inhibitory ICs. Lastly, we discuss the potential therapeutic approaches and future directions for AML treatment, emphasizing the potential of targeting metabolic and immune checkpoints in AML BMM as prognostic and therapeutic targets. In conclusion, the modulation of these processes through the use of directed drugs opens up new promising avenues in combating AML. Thereby, a comprehensive elucidation of the significance of these AML BMM cells' metabolic and immune checkpoints and signaling pathways on leukemic cells can be undertaken in the future investigations. Additionally, these checkpoints and cells should be considered plausible multi-targeted therapies for AML in combination with other conventional treatments in AML. Video Abstract.

Novel Combination of Surface Markers for the Reliable and Comprehensive Identification of Human Thymic Epithelial Cells by Flow Cytometry: Quantitation and Transcriptional Characterization of Thymic Stroma in a Pediatric Cohort

Thymic epithelial cells (TECs) are essential in supporting the development of mature T cells from hematopoietic progenitor cells and facilitate their lineage-commitment, proliferation, T-cell receptor repertoire selection and maturation. While animal model systems have greatly aided in elucidating the contribution of stromal cells to these intricate processes, human tissue has been more difficult to study, partly due to a lack of suitable surface markers comprehensively defining human TECs. Here, we conducted a flow cytometry based surface marker screen to reliably identify and quantify human TECs and delineate medullary from cortical subsets. These findings were validated by transcriptomic and histologic means. The combination of EpCAM, podoplanin (pdpn), CD49f and CD200 comprehensively identified human TECs and not only allowed their reliable distinction in medullary and cortical subsets but also their detailed quantitation. Transcriptomic profiling of each subset in comparison to fibroblasts and endothelial cells confirmed the identity of the different stromal cell subsets sorted according to the proposed strategy. Our dataset not only demonstrated transcriptional similarities between TEC and cells of mesenchymal origin but furthermore revealed a subset-specific distribution of a specific set of extracellular matrix-related genes in TECs. This indicates that TECs significantly contribute to the distinct compartmentalization - and thus function - of the human thymus. We applied the strategy to quantify TEC subsets in 31 immunologically healthy children, which revealed sex-specific differences of TEC composition early in life. As the distribution of mature CD4- or CD8-single-positive thymocytes was correspondingly altered, the composition of the thymic epithelial compartment may directly impact on the CD4-CD8-lineage choice of thymocytes. We prove that the plain, reliable strategy proposed here to comprehensively identify human TEC subpopulations by flow cytometry based on surface marker expression is suitable to determine their frequency and phenotype in health and disease and allows sorting of live cells for downstream analysis. Its use reaches from a reliable diagnostic tool for thymic biopsies to improved phenotypic characterization of thymic grafts intended for therapeutic use.

Impact of Concomitant Aberrant CD200 and BCL2 Overexpression on Outcome of Acute Myeloid Leukemia: A Cohort Study from a Single Center

Objective:

CD200 and BCL2 overexpression is independently associated with inferior survival in acute myeloid leukemia (AML), and these two factors are frequently co-expressed; however, no data are available on the role of concomitant aberrant CD200 and BCL2 expression on outcome of AML patients. We aimed to elucidate the prognostic role of CD200/BCL2 co-expression and its association with specific leukemia subsets.

Materials and Methods:

We analyzed 242 adult AML patients uniformly treated with intensive chemotherapy, evaluating the impact of CD200 and BCL2 expression on complete remission (CR), disease-free survival, and overall survival (OS).

Results:

CD200 and BCL2 were expressed in 139 (57.4%) and 137 (56.6%) cases, respectively, with 92 patients (38%) displaying double positivity (DP), 58 (24%) displaying double negativity (DN), and 92 patients expressing only either CD200 (n=47) or BCL2 (n=45). CR was achieved in 71% of cases, being less frequent in DP patients (60%) compared to other groups (76%-81%, p<0.001). In the whole population 3-year OS was 44%, being lower in DP patients (28%) than in patients with single CD200 or BCL2 expression (47%) or DN cases (60%; p=0.004). Other factors associated with worse OS were advanced age, CD34 positivity, secondary AML, and high white blood cell count at diagnosis; combining these 4 factors with CD200/BCL2 DP, we identified 6 groups with significantly different rates of survival (3-year OS ranging from 90% to 0%).

Conclusion:

Our data support a synergistic effect of CD200 and BCL2 in AML cells, conferring an enhanced survival capacity in a permissive microenvironment and resulting in worse prognosis.

Clinical Importance of CD200 Expression in Colorectal Liver Metastasis

BACKGROUND

Approximately 30% of patients diagnosed with colorectal cancer (CRC) develop liver metastases. We evaluated the role of CD200, a potent immunosuppressive molecule, in colorectal liver metastases (CRLM).

METHODS

We examined 110 patients who underwent curative liver resection for CRLM at our institution between 2000 and 2016. Based on the results of immunohistochemical analysis, the patients were divided into high-CD200 (n = 47) and low-CD200 (n = 63) expression groups. The relationships between CD200 expression and various clinicopathological outcomes were investigated.

RESULTS

The overall survival (OS) of patients in the high-CD200 group was significantly worse than that in the low-CD200 group (p = 0.009). Multivariate analysis showed that the independent prognostic factors in CRLM were maximum tumor size > 30 mm (p = 0.002), preoperative carcinoembryonic antigen level > 20 ng/mL (p < 0.001), primary CRC N2-3 (p = 0.049), and high-CD200 expression (p = 0.004). Furthermore, CD4+, CD8+, and CD45RO+ tumor-infiltrating lymphocytes in CRLM were significantly higher in the low-CD200 group than in the high-CD200 group (p = 0.005, p = 0.001, and p < 0.001, respectively). In addition, patients who had received preoperative chemotherapy had higher CD200 expression than those who had not received preoperative chemotherapy, and OS was significantly worse in patients in the high-CD200 group who had received preoperative chemotherapy.

CONCLUSIONS

CD200 expression was an independent prognostic factor in CRLM. CD200 may play a critical role in tumor immunity in CRLM, and can therefore be used as a potential therapeutic target in CRLM.

Overexpression of CD200 and CD123 is a major influential factor in the clinical course of pediatric acute myeloid leukemia

Acute myeloid leukemia (AML) accounts for approximately 20% of all pediatric acute leukemias. The outcome of AML is still unsatisfactory. CD123 and CD200 were demonstrated to play important roles in hematological malignancies. The aim of this study was to investigate the impact of CD200 and CD123 overexpression and the influence of both proteins on the clinical presentation and disease outcome. Bone marrow (BM) samples from 89 pediatric AML patients were obtained at presentation and after therapy. Cells from the bulk population and from the leukemia stem cell (LSC) compartment were examined by multi parametric flow cytometry. In the bulk population, CD200 was positive in 64/89 (71.9) samples, CD123 was positive in 62/89 (69.7%) samples, and dual CD200 and CD123 positivity was observed in 54/89 (60.7%) samples. CD200/CD123 expressions were observed in LSCs in 64/60 samples respectively (71.9%/67.4%), and co-expressed in 51 samples (57.3%). CD200 was overexpressed in secondary AML (p < 0.05). A multivariate analysis revealed that minimal residual disease (MRD) and lymphadenopathy were associated with CD200 overexpression. Moreover, lymphadenopathy, low platelet count, and MRD were independently associated with CD123 expression. The co-expression of CD200 and CD123 demonstrated a statistically significant relationship with unfavorable cytogenetic karyotypes and high total leucocyte count (TLC). The expression of CD200 and CD123 alone and together had an adverse impact on complete remission (CR), MRD positivity, and overall survival (OS). Cases with MRD on day 28 after induction displayed stable expression patterns of CD200 and CD123. CD200 and CD123 both had a negative influence on clinical presentation and treatment outcome, which remarkably worsened when both were concomitantly overexpressed. CD200 and CD123 can therefore be used as markers of MRD in AML and may also serve as therapeutic targets.

Plasma levels of norepinephrine and expression levels of ß2-adrenergic receptor gene correlate with the incidence of acute graft-versus-host disease

Background: Acute graft-versus-host disease is a major complication in allogeneic hematopoietic stem-cell transplantation. Epinephrine and norepinephrine are stress hormones which affect many cells, including immune cells through interaction with adrenergic receptors, mainly β2-adrenergic receptor. The immunomodulatory effects of epinephrine, norepinephrine, and signaling of the adrenergic receptor have been shown to decrease the probability of the acute graft-versus-host disease in animal models. The aim of our study was to investigate the possible correlations between the serum levels of epinephrine and norepinephrine and also leukocytic expression levels of β2-adrenergic receptor with the incidence of acute graft-versus-host disease in patients undergoing allogeneic hematopoietic stem-cell transplantation. Methods: In this study, the plasma levels of epinephrine and norepinephrine and the leukocytic expression of β2-adrenergic receptor gene were measured and compared in allogeneic hematopoietic stem-cell transplantation patients with and without acute graft-versus-host disease. Data were analyzed and illustrated using SPSS 19 and GraphPad Prism 6. The student T-test, Pearson, and Spearman's tests were performed and p<0.05 was considered as significant. Results: We showed that the plasma levels of norepinephrine and the relative amount of the mRNA of β2-adrenergic receptor at 7 and 21 days after allogeneic hematopoietic stem-cell transplantation were significantly lower in patients with acute graft-versus-host disease than recipients without acute graft-versus-host disease. There were also negative correlations between the plasma levels of norepinephrine, leukocytic levels of the mRNA of β2-adrenergic receptor, and the incidence of acute graft-versus-host disease. Conclusion: Our results suggest that stress hormones and their receptor might have a role in preventing acute graft-versus-host disease and could be promising factors in controlling the outcome of allogeneic hematopoietic stem-cell transplantation.

Prognostic Value of CD200 Expression and Soluble CTLA-4 Concentrations in Intermediate and High-Risk Myelodysplastic Syndrome Patients

OBJECTIVE

This study was designed in order to identify the prognostic relevance of CD200 expression and soluble Cytotoxic T-lymphocyte antigen-4 (CTLA-4) levels in myelodysplastic syndrome (MDS) patients.

METHODS

The study included 57 MDS (37 intermediate and 20 high risk) patients and 10 controls. For all of included patients; CD200 expression was identified by flowcytometry on CD33 positive cells and soluble CTLA-4 (CD152) concentration was determined by ELISA.

RESULTS

CD200 positive expression was detected in 32/57 (56.1%) of MDS cases, the mean serum CTLA-4 concentrations were significantly higher in MDS patients as compared to controls (P<0.01). Significant association between high CD200 positive expression; high CTLA-4   concentration levels and   MDS risk stages being higher in high risk MDS group as compared to intermediate risk one (P < 0.01).  After 36-month follow-up; the subgroup of MDS patients with high expression of CD200; and high serum CTLA-4 concentrations showed high death rate and high frequency of acute myeloid leukemia transformation.

CONCLUSIONS

CD200 positive expression could be considered as a new prognostic marker for risk stratification of MDS patients. CD200 expression may exert its effect through upregulation of CTLA-4.<br />.

Chemotherapy-Induced Tumor Cell Death at the Crossroads Between Immunogenicity and Immunotolerance: Focus on Acute Myeloid Leukemia

In solid tumors and hematological malignancies, including acute myeloid leukemia, some chemotherapeutic agents, such as anthracyclines, have proven to activate an immune response via dendritic cell-based cross-priming of anti-tumor T lymphocytes. This process, known as immunogenic cell death, is characterized by a variety of tumor cell modifications, i.e., cell surface translocation of calreticulin, extracellular release of adenosine triphosphate and pro-inflammatory factors, such as high mobility group box 1 proteins. However, in addition to with immunogenic cell death, chemotherapy is known to induce inflammatory modifications within the tumor microenvironment, which may also elicit immunosuppressive pathways. In particular, DCs may be driven to acquire tolerogenic features, such as the overexpression of indoleamine 2,3-dioxygensase 1, which may ultimately hamper anti-tumor T-cells via the induction of T regulatory cells. The aim of this review is to summarize the current knowledge about the mechanisms and effects by which chemotherapy results in both activation and suppression of anti-tumor immune response. Indeed, a better understanding of the whole process underlying chemotherapy-induced alterations of the immunological tumor microenvironment has important clinical implications to fully exploit the immunogenic potential of anti-leukemia agents and tune their application.

Dysregulation of helper T lymphocytes in esophageal squamous cell carcinoma (ESCC) patients is highly associated with aberrant production of miR-21

Dysregulation of helper T (Th) cell subsets has been contributed to the initiation and propagation of esophageal squamous cell carcinoma (ESCC). Different microRNAs (miRNAs) have been reported to control the development and functions of tumor-associated immune cells in ESCC. Here, we aimed to assess the IL-10, TGF-β, IFN-γ, and IL-17a-producing CD3+CD8- T cells in association whit miR-21, miR-29b, miR-106a, and miR-155 expression in ESCC patients. A total of 34 ESCC patients including 12 newly diagnosed (ND) and 22 under-treatment (UT) cases and also 34 age-matched healthy donors were enrolled. Flow cytometric characterization of stimulated T cells was performed by staining of the cells with fluorescent conjugated specific anti-human CD3 and CD8 cell surface markers as well as IL-17a, IFN-γ, IL-10, and TGF-β intracytoplasmic cytokines. Circulating RNA was extracted from the plasma, and qRT-PCR was used to evaluate the expression of microRNAs. TGF-β plasma levels were also assessed by ELISA. Results showed that the frequency of Th cells was significantly reduced in patients. A significant increase in Treg as well as Th17 cells population in both patient subgroups was observed. ND patients showed elevated level of Th1 cells and IL-10. However the mean expression of IFN-γ was significantly decreased in Th cells. We also detected higher level of miR-21 in the ESCC patients which was significantly correlated with different subsets of Th cells. Our findings revealed that immune response related to the Th cells is highly impaired in ESCC patients. Association between miR-21 and Th subsets could be correlated with the impairment of anti-tumor immunity and ESCC pathogenesis, which could be potentially used as an important target for immunotherapeutic approaches.

Interaction of CD200 Overexpression on Tumor Cells with CD200R1 Overexpression on Stromal Cells: An Escape from the Host Immune Response in Rectal Cancer Patients

CD200 imparts an immunoregulatory signal through its receptor, CD200R1, leading to the suppression of tumor specific immunity. The mechanism of CD200:CD200R1 signaling pathway is still uncertain. Our aim was to investigate the expression and localization of CD200 and its receptor CD200R1 and their clinical significance in rectal cancer patients. We examined the immunohistochemical expressions and localizations of CD200 and CD200R1 in 140 rectal cancer patients. Among the patients, 79 underwent the preoperative radiotherapy and the others were untreated prior to the surgery. In addition, 121 matched normal rectal mucosa samples were evaluated. The results of immunohistochemical analysis showed a strikingly high level of CD200 in tumor cells (p=0.001) and CD200R1 expression in normal mucosal epithelium and stromal cells. Importantly, CD200R1 was overexpressed in stromal cells of the metastatic cancer patients compared to patients without metastases (p=0.002). More than that, 87% of metastatic patients had a phenotype of upregulated CD200 in tumor cells accompanied by overexpressed CD200R1 in stromal cells. In addition, low levels of CD200 were correlated with improved overall survival in untreated patients. We showed that tumor-stroma communication through CD200 and its receptor interaction is selected in patients with high risk of relapse. High levels of these molecules support instigation of the far and local metastatic nest that provides solid ground for metastasis. Our current data also disclose a mechanism by which CD200:CD200R1 affects tumor progression and may strengthen the feasibility of targeting CD200 or CD200R1 as anticancer strategy.

Therapeutic Antibodies for Myeloid Neoplasms-Current Developments and Future Directions

Therapeutic monoclonal antibodies (mAbs) such as antibody-drug conjugates, ligand-receptor antagonists, immune checkpoint inhibitors and bispecific T cell engagers have shown impressive efficacy in the treatment of multiple human cancers. Numerous therapeutic mAbs that have been developed for myeloid neoplasms, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), are currently investigated in clinical trials. Because AML and MDS originate from malignantly transformed hematopoietic stem/progenitor cells-the so-called leukemic stem cells (LSCs) that are highly resistant to most standard drugs-these malignancies frequently relapse and have a high disease-specific mortality. Therefore, combining standard chemotherapy with antileukemic mAbs that specifically target malignant blasts and particularly LSCs or utilizing mAbs that reinforce antileukemic host immunity holds great promise for improving patient outcomes. This review provides an overview of therapeutic mAbs for AML and MDS. Antibody targets, the molecular mechanisms of action, the efficacy in preclinical leukemia models, and the results of clinical trials are discussed. New developments and future studies of therapeutic mAbs in myeloid neoplasms will advance our understanding of the immunobiology of these diseases and enhance current therapeutic strategies.

An autologous tumor vaccine for CLL

Chronic Lymphocytic Leukemia B cells (CLL) are malignant cells which retain at least some functions of normal B cells. Paramount amongst the latter is that when such cells are appropriately stimulated, they are able to present antigens, including any potential tumor antigens, making them excellent choices as a candidate tumor vaccine. We show that following stimulation of CLL cells with Phorbol myristic acetate, IL-2, the TLR7 agonist imiquimod (P2I) and ionomycin (P2Iio), markedly increased expression of CD54 and CD83 was seen, indicative of B cell activation and a transition to antigen-presenting cells. However, this occurred in the context of augmented expression of the known immunoregulatory molecule, CD200. Accordingly we explored the effect of stimulation of CLL cells with P2Iio, followed by coating of cells with a non-depleting anti-CD200mAb, on the ability of those cells to immunize PBL in vitro to become cytotoxic to CLL cells, or to protect NOD-SCIDγc^null (NSG) mice from subsequent CLL tumor challenge. Our data indicate that this protocol is effective in inducing CD8⁺ CTL able to lyse CLL cells in vitro, and decrease tumor burden in vivo in spleen and marrow of mice injected with CLL cells. Pre-treatment of mice with a CD8 depleting antibody before vaccination with P2Iio/anti-CD200 coated cells abolished any protection seen. These data suggest a potential role for blockade of CD200 expression on CLL cells as a component of a tumor vaccination strategy.

Sodium valproate modulates immune response by alternative activation of monocyte-derived macrophages in systemic lupus erythematosus

The anti-inflammatory role of macrophages in apoptotic cells (ACs) clearance is involved in Systemic Lupus Erythematosus (SLE) pathogenesis. The efferocytic capability of macrophages is altered by M1/M2 polarization. Histone deacetylase inhibitors (HDACi) are proposed to enhance the expansion of M2 macrophages. Sodium valproate (VPA) is an HDACi with different anti-inflammatory properties. Here, we aimed to investigate the effects of HDACi by VPA on the polarization of monocyte-derived macrophages (MDMs) and regulating the expression of anti-inflammatory cytokines in SLE. We studied the ex vivo alterations of MDMs among 15 newly diagnosed SLE patients and 10 normal subjects followed by ACs and VPA treatments. M1/M2 polarization was assessed by expression of CD86/CD163, IL1-β, IDO-1, and MRC-1 among treated and non-treated MDMs. We also evaluated the production of IL-10, IL-12, TGF-β1, and TNF-α cytokines in the cell culture supernatants. CD163 was overexpressed upon VPA treatment, while CD86 showed no significant change. IL1-β and IDO-1 genes were significantly downregulated, and the mRNA expression of MRC-1 was increased among VPA-treated MDMs of SLE patients. The anti-inflammatory cytokines (IL-10 and TGF-β1) were overproduced while TNF-α level was decreased in response to VPA. The population of classically activated macrophages was more prevalent among SLE patients and efferocytosis was defected. VPA could successfully enhance the anti-inflammatory immune response through alternative activation of MDMs in SLE patients.

Checkpoint blockade in solid tumors and B-cell malignancies, with special consideration of the role of CD200

In the ontogeny of a normal immune response, a series of checkpoints must be overcome to ensure that unwanted and/or harmful self-directed activation responses are avoided. Many of the molecules now known to be active in this overseeing of the evolving immune activation cascade, contributing inhibitory signals to dampen an overexuberant response, belong to the immunoglobulin supergene family. These include members of the CD28/CTLA-4:B7.1/B7.2 receptor/ligand family, PD-1 and PDL-1, CD200 and CD200R, and the more recently described V-domain immunoglobulin suppressor of T-cell activation and its ligand (VSIG-3/IGSF11). Unfortunately, from the point of view of improving immunotargeting of cancer cells, triggering these checkpoint inhibitory signaling pathways, so necessary to maintain self-tolerance, simultaneously acts to prevent effective tumor immunity. The recent development of reagents, predominantly antibodies, to act as checkpoint blockade agents, has had a dramatic effect on human cancer treatment, with a marked reported success for anti-CTLA-4 and PD-1 in particular in clinical trials. This review provides a general overview of the data now available showing the promise of such treatments to our cancer armamentarium and elaborates in depth on the potential promise of what can be regarded as an underappreciated target molecule for checkpoint blockade in chronic lymphocytic leukemia and solid tumors, CD200.

Immunomodulation in systemic lupus erythematosus: induction of M2 population in monocyte-derived macrophages by pioglitazone

Macrophages have recently gained attention in systemic lupus erythematosus (SLE) pathogenesis for their role in the anti-inflammatory clearance of apoptotic cells. The M1/M2 polarization of macrophages improves efferocytic capability. Peroxisome proliferator-activated receptor γ is proposed to function in the expansion of the M2 subpopulation. Pioglitazone is a peroxisome proliferator-activated receptor γ agonist with a variety of anti-inflammatory effects. In this paper, we investigated the ex vivo alterations of monocyte-derived macrophages of 15 newly diagnosed SLE patients and 10 normal subjects triggered by apoptotic cells among SLE patients following pioglitazone treatment. The phagocytosis capacity of macrophages and M1/M2 polarization (CD86/CD163) was evaluated. The supernatants were also analyzed for the expression of interleukin (IL)-10, IL-12, transforming growth factor β1 and TNF-α. The mRNA expression of IL-1β and mannose receptor C-type 1 were also quantified among treated and non-treated monocyte-derived macrophages. We found that efferocytosis is defective among monocyte-derived macrophages of SLE patients and might be a major underlying mechanism involved in the sustained inflammation. Pioglitazone could enhance alternative activation of monocyte-derived macrophages and consequently immunomodulation in these patients.

Immunomodulatory Drugs: Immune Checkpoint Agents in Acute Leukemia

Intrinsic immune responses to acute leukemia are inhibited by a variety of mechanisms, such as aberrant antigen expression by leukemia cells, secretion of immunosuppressive cytokines and expression of inhibitory enzymes in the tumor microenvironment, expansion of immunoregulatory cells, and activation of immune checkpoint pathways, all leading to T cell dysfunction and/or exhaustion. Leukemic cells, similar to other tumor cells, hijack these inhibitory pathways to evade immune recognition and destruction by cytotoxic T lymphocytes. Thus, blockade of immune checkpoints has emerged as a highly promising approach to augment innate anti-tumor immunity in order to treat malignancies. Most evidence for the clinical efficacy of this immunotherapeutic strategy has been seen in patients with metastatic melanoma, where anti-CTLA-4 and anti-PD-1 antibodies have recently revolutionized treatment of this lethal disease with otherwise limited treatment options. To meet the high demand for new treatment strategies in acute leukemia, clinical testing of these promising therapies is commencing. Herein, we review the biology of multiple inhibitory checkpoints (including CTLA-4, PD-1, TIM-3, LAG-3, BTLA, and CD200R) and their contribution to immune evasion by acute leukemias. In addition, we discuss the current state of preclinical and clinical studies of immune checkpoint inhibition in acute leukemia, which seek to harness the body's own immune system to fight leukemic cells.

Glucocorticoid-induced leucine zipper expression is associated with response to treatment and immunoregulation in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disorder in which cytokine balance is disturbed. Glucocorticoids (GCs) are shown to balance immune response by transcriptional regulation of glucocorticoid receptor target genes such as Glucocorticoid-induced leucine zipper (GILZ) which has been introduced as an endogenous anti-inflammatory mediator. In the present study, we assessed the expression of GILZ in association with interferon-γ (IFN-γ), interleukine-10 (IL-10), and B lymphocyte stimulator (BLyS) plasma levels in SLE patients. A total of 40 female patients (18 under treatment and 22 newly diagnosed) were recruited in this study. Real-time RT PCR was conducted to quantify the mRNA expression of GILZ. The plasma levels of IFN-γ, IL-10, and BLyS were evaluated using ELISA method. GILZ was overexpressed among under treatment SLE patients. The mRNA expression of GILZ was significantly correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score. IFN-γ and BLyS were downregulated in response to therapies with negative correlations to GILZ. Moreover, IL-10 was upregulated among treated patients. The levels of IFN-γ and BLyS were correlated with the severity of disease, while IL-10 was negatively correlated with SLEDAI score. GILZ could be introduced as one of the acting molecules in mediating the regulatory effects of GCs on producing pro- and anti-inflammatory cytokines in SLE.

Ibrutinib treatment improves T cell number and function in CLL patients

BACKGROUND

Ibrutinib has been shown to have immunomodulatory effects by inhibiting Bruton's tyrosine kinase (BTK) and IL-2-inducible T cell kinase (ITK). The relative importance of inhibiting these 2 kinases has not been examined despite its relevance to immune-based therapies.

METHODS

Peripheral blood mononuclear cells from chronic lymphocytic leukemia (CLL) patients on clinical trials of ibrutinib (BTK/ITK inhibitor; n = 19) or acalabrutinib (selective BTK inhibitor; n = 13) were collected serially. T cell phenotype, immune function, and CLL cell immunosuppressive capacity were evaluated.

RESULTS

Ibrutinib markedly increased CD4+ and CD8+ T cell numbers in CLL patients. This effect was more prominent in effector/effector memory subsets and was not observed with acalabrutinib. Ex vivo studies demonstrated that this may be due to diminished activation-induced cell death through ITK inhibition. PD-1 and CTLA-4 expression was significantly markedly reduced in T cells by both agents. While the number of Treg cells remained unchanged, the ratio of these to conventional CD4+ T cells was reduced with ibrutinib, but not acalabrutinib. Both agents reduced expression of the immunosuppressive molecules CD200 and BTLA as well as IL-10 production by CLL cells.

CONCLUSIONS

Ibrutinib treatment increased the in vivo persistence of activated T cells, decreased the Treg/CD4+ T cell ratio, and diminished the immune-suppressive properties of CLL cells through BTK-dependent and -independent mechanisms. These features provide a strong rationale for combination immunotherapy approaches with ibrutinib in CLL and other cancers.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01589302 and NCT02029443. Samples described here were collected per OSU-0025.

FUNDING

The National Cancer Institute.

Overexpression of interferon-γ and indoleamine 2, 3-dioxygenase in systemic lupus erythematosus: relationship with the disease activity

Background:

Indoleamine 2, 3-dioxygenase (IDO) is a tryptophan catabolizing enzyme which is involved in immune regulation and autoimmune disorders such as systemic lupus erythematosus (SLE). Interferon-γ (IFN-γ) is an inflammatory cytokine which is the major inducer of IDO expression. Here, we evaluated the level of IFN-γ and IDO among SLE patients in correlation with the severity of SLE.

Methods:

Fifty-three SLE patients and 35 age matched healthy donors were enrolled in this study. Systemic lupus erythematosus disease activity index (SLEDAI) was used to calculate the disease activity. Real-time RT-PCR and ELISA were used to evaluate the gene expression of IDO and IFN-γ plasma concentration, respectively.

Results:

We showed that IDO-1, IDO-2 and IFN-γ were overexpressed among SLE patients significantly (p<0.0001). There were significant positive correlations between IFN-γ with the expression of IDO-1 (r=0.722, p<0.0001) and IDO-2 (r=0.682, p<0.0001). There were also positive correlations between SLEDAI scores with IDO-1 (r=0.675, p<0.0001), IDO-2 (r=0.727, p<0.0001) and IFN-γ (r=0.907, p<0.0001).

Conclusions:

IDO expression and IFN-γ level could be introduced as helpful biomarkers for the determination of disease severity in SLE patients.

Overexpression of interferon-γ and indoleamine 2, 3-dioxygenase in systemic lupus erythematosus: relationship with the disease activity

Background:

Indoleamine 2, 3-dioxygenase (IDO) is a tryptophan catabolizing enzyme which is involved in immune regulation and autoimmune disorders such as systemic lupus erythematosus (SLE). Interferon-γ (IFN-γ) is an inflammatory cytokine which is the major inducer of IDO expression. Here, we evaluated the level of IFN-γ and IDO among SLE patients in correlation with the severity of SLE.

Methods:

Fifty-three SLE patients and 35 age matched healthy donors were enrolled in this study. Systemic lupus erythematosus disease activity index (SLEDAI) was used to calculate the disease activity. Real-time RT-PCR and ELISA were used to evaluate the gene expression of IDO and IFN-γ plasma concentration, respectively.

Results:

We showed that IDO-1, IDO-2 and IFN-γ were overexpressed among SLE patients significantly (p<0.0001). There were significant positive correlations between IFN-γ with the expression of IDO-1 (r=0.722, p<0.0001) and IDO-2 (r=0.682, p<0.0001). There were also positive correlations between SLEDAI scores with IDO-1 (r=0.675, p<0.0001), IDO-2 (r=0.727, p<0.0001) and IFN-γ (r=0.907, p<0.0001).

Conclusions:

IDO expression and IFN-γ level could be introduced as helpful biomarkers for the determination of disease severity in SLE patients.

Overexpression of ATP1B1 predicts an adverse prognosis in cytogenetically normal acute myeloid leukemia

ATP1B1 encodes the Na,K-ATPase β subunit, a key regulator of the Na⁺ and K⁺ electrochemical gradients across the plasma membrane and an essential regulator of cellular activity. We used several microarray datasets to test the prognostic efficacy of ATP1B1 expression in cytogenetically normal acute myeloid leukemia (CN-AML). Within the primary cohort (n = 157), high ATP1B1 expression (ATP1B1^high) was associated with shorter overall survival (OS) and event-free survival (EFS) (P = 0.0068, P = 0.0039, respectively). Similar results were also obtained in the European Leukemia Net (ELN) Intermediate-I genetic category (OS: P = 0.0035, EFS: P = 0.0007). Multivariable analyses confirmed ATP1B1^high is an independent predictor of shorter OS (P = 0.042) and EFS (P = 0.035). Analysis of another CN-AML cohort confirmed that ATP1B1^high is associated with shorter OS (P = 0.0046, n = 162). In addition, up-regulation of oncogenes/onco-microRNAs such as MYCN, CCND2, CDK6, KIT and miR-155, among others, was associated with ATP1B1^high, which may be indicative of ATP1B1's leukemogenicity. Our results may improve risk stratification and indicate new therapeutic targets for CN-AML.

CD200R/Foxp3-mediated signalling regulates microglial activation

The heterogeneity of microglial functions have either beneficial or detrimental roles in specific physiological or pathological environments. However, the details of what transcriptional mechanisms induce microglia to take beneficial phenotypes remain unknown. Here, we report that Foxp3 is essential for beneficial outcome of the microglial response and depends upon signalling by the immunoglobulin CD200 through its receptor (CD200R). Foxp3 expression was up-regulated in microglia activated by excitotoxicity-induced hippocampal neuroinflammation. Suppression of CD200R prevented anti-inflammatory phenotype of microglia, but over-expression of Foxp3 enhanced it. Phosphorylation of STAT6, a downstream effector of CD200R, modulated transcription of Foxp3. Finally, CD200R/Foxp3-mediated signalling enhanced hippocampal neuronal viability and conferred a degree of neuroprotection, presumably by counteracting inducible nitric oxide synthase. We conclude that enhancement of Foxp3 through CD200R could be neuroprotective by targeting the microglia.

CD200R, a co-inhibitory receptor on immune cells, predicts the prognosis of human hepatocellular carcinoma

The inhibitory CD200:CD200 receptor axis is essential in preventing inflammatory responses during early microbial infection. It was reported in several tumor models that CD200 expression is closely associated to tumor progression and the blockade of this pathway may restore anti-tumor responses. Our study for the first time investigates the role of CD200:CD200R axis in relation to tumor progression and prognosis of human hepatocellular carcinoma. CD200 and CD200R protein expressions were evaluated by immunostaining on liver tissue specimens and we found higher expressions of CD200 and CD200R in HCC patients comparing to healthy controls. CD200 expresses in peritumoral, peritumoral stroma and intratumoral regions of HCC while CD200R predominantly expresses in peritumoral stroma. Furthermore, protein intensity of CD200R is positively associated to the diameter of tumor and alpha-fetoprotein level, in addition, patients with higher pathological grade and absence of tumor capsule exhibit higher CD200R expression. CD200R predominantly expresses on infiltrating macrophages and may associate with liver injury. Moreover, both overall and recurrence-free survival rates are significantly lower in patients with high CD200R expression comparing to those with low CD200R expression. Our findings suggest a promising role of CD200R as a prognostic marker in predicting elevated recurrence and reduced survival, and a potential therapeutic target in treating hepatocellular carcinoma.

Clinical impact of CD200 expression in patients with acute myeloid leukemia and correlation with other molecular prognostic factors

CD200, a protein belonging to the immunoglobulin superfamily, has been associated with a poor prognosis in lymphoproliferative disorders and in acute leukemia. We studied the expression of CD200 in a series of 244 patients with diagnosis of acute myeloid leukemia (AML), to evaluate its impact on outcome and its possible association with other known prognostic factors.

CD200 was found in 136/244 (56%) patients, in 41 of whom (30%) with high intensity of expression (MFI ≥ 11). CD200 was more frequent in secondary compared to de novo leukemia (p = 0.0006), in CD34 positive cases (p = 0.00001), in Bcl2 overexpressing cases (p = 0.01), in those wild-type Flt3 (p = 0.004) and with favorable or unfavorable compared to intermediate karyotype (p = 0.0003). CD200+ patients have a two-fold lower probability to attain complete remission, both in univariate (p = 0.006) and multivariate (p = 0.04) analysis. The negative impact of CD200 was found also in overall survival (p = 0.02) and was correlated with the intensity of expression of the molecule (p = 0.024). CD200 has an additive negative impact on survival in patients with unfavorable cytogenetic (p = 0.046) and in secondary leukemia (p = 0.05), and is associate with a worsening of outcome in patients with favorable biological markers, such as mutated NPM (p = 0.02), wild-type Flt3 (p = 0.034), negativity of CD34 (p = 0.03) and of CD56 (p = 0.03).

In conclusion, CD200 is emerging as both a prognostic factor and a potential target of novel therapeutic approaches for AML, aiming to reverse the “do not eat me” signal of CD200 or to manipulate the suppressive immune microenvironment induced by CD200 binding to its receptor.

Mesenchymal Stem and Progenitor Cells in Normal and Dysplastic Hematopoiesis-Masters of Survival and Clonality?

Myelodysplastic syndromes (MDS) are malignant hematopoietic stem cell disorders that have the capacity to progress to acute myeloid leukemia (AML). Accumulating evidence suggests that the altered bone marrow (BM) microenvironment in general, and in particular the components of the stem cell niche, including mesenchymal stem cells (MSCs) and their progeny, play a pivotal role in the evolution and propagation of MDS. We here present an overview of the role of MSCs in the pathogenesis of MDS, with emphasis on cellular interactions in the BM microenvironment and related stem cell niche concepts. MSCs have potent immunomodulatory capacities and communicate with diverse immune cells, but also interact with various other cellular components of the microenvironment as well as with normal and leukemic stem and progenitor cells. Moreover, compared to normal MSCs, MSCs in MDS and AML often exhibit altered gene expression profiles, an aberrant phenotype, and abnormal functional properties. These alterations supposedly contribute to the “reprogramming” of the stem cell niche into a disease-permissive microenvironment where an altered immune system, abnormal stem cell niche interactions, and an impaired growth control lead to disease progression. The current article also reviews molecular targets that play a role in such cellular interactions and possibilities to interfere with abnormal stem cell niche interactions by using specific targeted drugs.

Immune Cells in Cancer Therapy and Drug Delivery

Recent studies indicate the critical role of tumour associated macrophages, tumour associated neutrophils, dendritic cells, T lymphocytes, and natural killer cells in tumourigenesis. These cells can have a significant impact on the tumour microenvironment via their production of cytokines and chemokines. Additionally, products secreted from all these cells have defined specific roles in regulating tumour cell proliferation, angiogenesis, and metastasis. They act in a protumour capacity in vivo as evidenced by the recent studies indicating that macrophages, T cells, and neutrophils may be manipulated to exhibit cytotoxic activity against tumours. Therefore therapy targeting these cells may be promising, or they may constitute drug or anticancer particles delivery systems to the tumours. Herein, we discussed all these possibilities that may be used in cancer treatment.

Lung CD200 Receptor Activation Abrogates Airway Hyperresponsiveness in Experimental Asthma

In allergic asthma, homeostatic pathways are dysregulated, which leads to an immune response toward normally innocuous antigens. The CD200-CD200 receptor pathway is a central regulator of inflammation, and CD200 expression was recently found to be down-regulated in circulating leukocytes of patients with asthma. Given the antiinflammatory properties of CD200, we investigated whether local delivery of recombinant CD200 (rCD200) could reinstate lung homeostasis in an experimental model of asthma. Brown Norway rats were sensitized with ovalbumin (OVA) and alum. rCD200 was intratracheally administered 24 hours before OVA challenge, and airway responsiveness to methacholine was measured 24 hours after the allergen challenge. Inflammation was also assessed by measuring cell recruitment and cytokine levels in bronchoalveolar lavages, as well as lung and draining lymph node accumulation of dendritic cells (DCs) and T cells. In sensitized rats, rCD200 abolished airway hyperresponsiveness, whereas the sham treatment had no effect. In addition, rCD200 strongly reduced OVA-induced lung accumulation of myeloid DCs, CD4(+) T cells, and T helper type 2 cells. This was associated with a strong reduction of OVA-induced IL-13 level and with an increase of IL-10 in supernatants of bronchoalveolar lavages. Lung eosinophilia and draining lymph node accumulation of myeloid DCs and T cells were not affected by rCD200. Overall, these data reveal that rCD200 can inhibit airway hyperresponsiveness in a model of asthma by a multistep mechanism associated with local alterations of the T cell response and the cytokine milieu.

Immunotherapy in acute myeloid leukemia

Despite the remarkable progress made in some leukemias such as CML and CLL, cytotoxic treatment for AML remains essentially unchanged over the last 4 decades. Several lines of evidence, including the graft versus leukemia effect associated with allogeneic hematopoietic stem cell transplantation (HSCT), suggest that immunotherapy is an active modality in AML. Given the lack of progress for chemotherapy in this disease, many novel immunologic treatment approaches have been explored. The goals of non-transplant-based immune approaches have largely consisted of the stimulation or restoration of endogenous immune responses or the targeting of specific tumor antigens by immune cells. These strategies have been associated with less toxicity than allogeneic HSCT but typically have inferior efficacy. Allogeneic HSCT exploits major and minor histocompatibility differences between the donor and recipient in order to recognize and eradicate malignancy. With the recognition that the immune system itself provides a basis for treating AML, immunotherapy continues to be an attractive modality to exploit in the treatment of this disease.

Inhibitory CD200R and proapoptotic CD95/CD95L molecules on innate immunity cells are modulated by cardiac surgery

Introduction:

Cardiac surgery directly initiates a systemic inflammatory response with the activation of both cellular and humoral parts of the immune system. Exaggerated immune system activation is associated with a risk of life-threatening multi-organ dysfunction (MOD) and increased morbidity and mortality in the postoperative period. The immune system response is regulated and terminated by inhibitory mechanisms, including the regulatory membrane molecules, such as CD200R, CD95, CD95L and soluble sCD200R.

Methods:

We measured the expression of CD95, CD95L, CD200R and sCD200R molecules in granulocyte and monocyte populations in blood samples of 30 patients who underwent coronary artery bypass grafting (CABG) using cardiopulmonary bypass (CPB). Samples collected before surgery, after surgery and in the postoperative period were analyzed by flow cytometry and ELISA.

Results:

We found a significant increase in the percentage of granulocytes featuring the anti-inflammatory molecule CD200R (from 5% to 17.8%) after surgery. We presume that these cells were less susceptible to apoptosis because they rarely expressed CD95 as the CD200R+CD95– granulocyte sub-population prevailed. Only a small percentage of CD200R+ granulocytes expressed simultaneously CD95 (from 0.5 to 2.06 %). This small population of CD200R+CD95+ cells decreased expression of CD200R after surgery and, thus, was likely to be a source of increased sCD200R in serum (from 96 to 294 ng/mL). Also, the expression of CD95L on CD200R+ granulocytes and CD95 on CD200R+ monocytes was affected by surgery. The percentage of CD200R+ monocytes was elevated on the 1st postoperative day (from 30.6 to 49.4 %) and dropped below the preoperative value on the 7th day after surgery (from 30.6 to 19.8 %). This population comprised mainly CD200R+CD95+ monocytes in which the enhanced expression of CD95 was found.

Conclusion:

Our data show that the expression of CD200R, CD95 and CD95L was influenced by cardiac surgery and imply the role of these membrane molecules in cell regulation–inhibition and apoptosis following cardiac surgery.

Bidirectional effect of CD200 on breast cancer development and metastasis, with ultimate outcome determined by tumor aggressiveness and a cancer-induced inflammatory response

CD200 acts through its receptor (CD200R) to inhibit excessive inflammation. The role of CD200-CD200R1 interaction in tumor immunity is poorly understood. In this study, we examined the role of CD200-CD200R1 interaction in the progression and metastasis of highly aggressive 4THM murine-breast carcinoma using CD200 transgenic (CD200(tg)) and CD200R1 knock-out (CD200R1(-)(/-)) BALB/c mice. 4THM cells induce extensive visceral metastasis and neutrophil infiltration in affected tissues. CD200 overexpression in the host was associated with decreased primary tumor growth and metastasis, whereas lack of CD200R1 expression by host cells was associated with enhanced visceral metastasis. Absence of CD200R1 expression led to decreased tumor-infiltrating-cytotoxic T cells and increased the release of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-6. In contrast, CD200 overexpression led to increased tumor-induced interferon-γ and IL-10 response and decreased TNF-α and IL-6 release. Neutrophil infiltration of tissues was markedly decreased in CD200(tg) animals and increased in CD200R1(-/-) mice. These findings are contradictory to what has been reported in the EMT6 mouse breast-cancer model. Other distinguishing features of tumor elicited by EMT6 and 4THM cell injections were also examined. Visceral tissues from mice bearing EMT6 tumors showed a lack of neutrophil infiltration and decreased IL-6 release in CD200R1(-/-) mice. EMT6 and 4THM cells also differed in vimentin expression and in vitro migration rate, which was markedly lower in EMT6 tumors. These results support the hypothesis that CD200 expression can alter immune responses, and can inhibit metastatic growth of tumor cells that induce systemic and local inflammatory response. Increasing CD200 activity/signaling might be an important therapeutic strategy for treatment of aggressive breast carcinomas.

The interaction between microglia and neural stem/precursor cells

In the adult mammalian brain, neurogenesis from neural stem/precursor cell occurs within two regions, the subgranular zone (SGZ) in the dentate gyrus (DG) and the subventricular zone (SVZ) lining the lateral ventricles. The function of neural stem cell is enhanced by external stimuli, such as injury and inflammation. Microglia, as the main immune modulating cells, play important roles in the central nervous system (CNS). Recently, select discoveries reported that microglia might influence the proliferation, differentiation and survival of neural precursor cells (NPCs). Other studies revealed that NPCs might reversibly regulate the function of microglia. Accordingly, in this review we focus on the interaction between microglia and NPCs.

T-cell immune suppression in patients with hematologic malignancies: clinical implications

SUMMARY 

The reversion of immune suppression and restoration of T-cell function against leukemia remains a significant clinical challenge. However, the advent of improved antileukemia-specific T-cell induction and the generation of gene-modified T cells has extended cellular immunotherapy to hematological malignancies. Numerous immunotherapeutic protocols have been developed aiming to enhance antileukemia T-cell immune function, eliminate leukemic cells and prevent relapse. By contrast, abnormal expression of CTLA-4 and PD1/PD-L1 plays a critical role in effector T-cell responses and increases Treg suppressive activity in patients with tumors; therefore, blocking CTLA-4, PD1 and PD-L1 is a novel approach for immunotherapy.

Investigation of a novel biomarker, neuropilin-1, and its application for poor prognosis in acute myeloid leukemia patients

According to the previous studies, numerous biomarkers impact on the prognosis of acute myeloid leukemia (AML) and the prediction for AML had been improved tremendously in the past decades. However, accurate risk-stratification at diagnosis or prognosis remained difficult. In order to further investigate the prognosis evaluation biomarker, the transcription or expression of neuropilin-1 (NRP-1) in 87 AML patients and 32 non-malignant controls were examined. Real-time quantitative polymerase chain reaction (RT-PCR) and Western blot were used to detect the NRP-1 expression. Clinical data were collected and analyzed for the 87 AML patients. The results indicated that high NRP-1 expression discriminated the complete remission (CR) rate of AML patients (22.12 % vs. 68.04 % for AML, P < 0.01). De novo AML patients tended to express higher NRP-1 proteins than relapsed AML patients. The overall survival (OS) and relapse-free survival (RFS) rate of the high NRP-1 expression patients decreased significantly compared with the low NRP-1 expression patients (P < 0.001). NRP-1 was revealed to be an independent risk factor for OS in AML (P = 0.003). In conclusion, NRP-1 could predict the shorter OS and RFS rate, and also related with the CR response in AML. Therefore, NRP-1 may act as a more aggressive and promising predictor for the poor prognosis of AML.

Interleukin 12: still a promising candidate for tumor immunotherapy?

Interleukin 12 (IL-12) seemed to represent the ideal candidate for tumor immunotherapy, due to its ability to activate both innate (NK cells) and adaptive (cytotoxic T lymphocytes) immunities. However, despite encouraging results in animal models, very modest antitumor effects of IL-12 in early clinical trials, often accompanied by unacceptable levels of adverse events, markedly dampened hopes of the successful use of this cytokine in cancer patients. Recently, several clinical studies have been initiated in which IL-12 is applied as an adjuvant in cancer vaccines, in gene therapy including locoregional injections of IL-12 plasmid and in the form of tumor-targeting immunocytokines (IL-12 fused to monoclonal antibodies). The near future will show whether this renewed interest in the use of IL-12 in oncology will result in meaningful therapeutic effects in a select group of cancer patients.

Interplay between human microglia and neural stem/progenitor cells in an allogeneic co-culture model

Experimental neural cell therapies, including donor neural stem/progenitor cells (NPCs) have been reported to offer beneficial effects on the recovery after an injury and to counteract inflammatory and degenerative processes in the central nervous system (CNS). The interplay between donor neural cells and the host CNS still to a large degree remains unclear, in particular in human allogeneic conditions. Here, we focused our studies on the interaction of human NPCs and microglia utilizing a co-culture model. In co-cultures, both NPCs and microglia showed increased survival and proliferation compared with mono-cultures. In the presence of microglia, a larger subpopulation of NPCs expressed the progenitor cell marker nestin, whereas a smaller group of NPCs expressed the neural markers polysialylated neural cell adhesion molecule, A2B5 and glial fibrillary acidic protein compared with NPC mono-cultures. Microglia thus hindered differentiation of NPCs. The presence of human NPCs increased microglial phagocytosis of latex beads. Furthermore, we observed that the expression of CD200 molecules on NPCs and the CD200 receptor protein on microglia was enhanced in co-cultures, whereas the release of transforming growth factor-β was increased suggesting anti-inflammatory features of the co-cultures. To conclude, the interplay between human allogeneic NPCs and microglia, significantly affected their respective proliferation and phenotype. Neural cell therapy including human donor NPCs may in addition to offering cell replacement, modulate host microglial phenotypes and functions to benefit neuroprotection and repair.