The Chemokine System in Experimental and Clinical Hematology

Study on the mechanism of CXCL12/CXCR4-axis-mediated upregulation of IL-8 and IL-6 on the biological function of acute T lymphocyte leukaemia cells

Blocking the CXCL12/CXCR4 axis can alter the biological functions of leukaemia cells. We hypothesise that interleukin (IL)-8 and IL-6 play an important role in this process. To test this hypothesis, we established a co-culture model of leukaemia cells and bone marrow stromal cells. Treatment of cells with AMD3100, a CXCR4 antagonist, and G-CSF blocked the CXCL12/CXCR4 axis, inducing biological changes in the leukaemia cells and altering IL-8 and IL-6 levels. Subsequently, after stimulating the CXCL12/CXCR4 axis, specific pathway blockers were employed to assess the role of four candidate signalling pathways in this process. ELISA results confirmed that MG-132 (10 μm) inhibits IL-8 expression and that the NF-κB signalling pathway contributes to this effect. Moreover, treatment with Perifosine, an AKT inhibitor, inhibited IL-6 expression. In addition, changes in the NF-κB signalling pathway inhibited IL-8 expression. Treatment with SP600125, a Jun N-terminal kinase inhibitor, and Perifosine also inhibited IL-8 expression; however, this effect occurred later. IL-6 expression was also lower in the Perifosine group; hence, inhibiting the PI3K/AKT signalling pathway can reduce IL-6 expression. This process requires the participation of multiple signalling pathways to regulate IL-8 and IL-6 expression. Therefore, the associated mechanism is likely to be highly intricate, with potential cross-effects that may impact leukaemia pathogenesis. IL-6 and IL-8 are physiologically regulated by the CXCL12/CXCR4 axis, while the NF-κB and JNK/AP-1 pathways are required for IL-8 expression in T-cell acute lymphoblastic leukaemia. Accordingly, by upregulating IL-8, the bone marrow microenvironment and CXCL12/CXCR4 axis may contribute to T-cell acute lymphoblastic leukaemia pathogenesis.

Importance of the female reproductive tract microbiome and its relationship with the uterine environment for health and productivity in cattle: A review

Once thought to be sterile, the reproductive tract microbiome has been characterized due to the transition from culture-dependent identification of bacteria to culture-independent sequencing methods. The urogenital microbiome was first identified in women through the Human Microbiome Project, which led to research in other species such as the bovine. Previous research focused on uterine bacteria associated with postpartum disease, but next generation sequencing methods identified a normal, healthy bacterial community of the reproductive tract of cows and heifers. Bacterial communities are now understood to differ between the uterus and vagina, and throughout the estrous cycle with changes in hormone dominance. In a healthy state, the bacterial communities largely interact with the uterine environment by assisting in maintaining the proper pH, providing and utilizing nutrients and metabolites, and influencing the immunological responses of the reproductive tract. If the bacterial communities become unbalanced due to an increase in potentially pathogenic bacteria, the health and fertility of the host may be affected. Although the presence of a reproductive tract microbiome has become widely accepted, the existence of a placental microbiome and in utero colonization of the fetus is still a popular debate due to conflicting study results. Currently, researchers are evaluating methods to manipulate the reproductive bacterial communities, such as diet changes and utilizing probiotics, to improve reproductive outcomes. The following review discusses the current understanding of the reproductive tract microbiome, how it differs between humans and cattle, and its relationship with the uterine environment.

Endometrial gene expression in response to lipopolysaccharide between estrous cycle phases and uterine horns in cattle

Uterine bacterial community abundances shift throughout the estrous cycle, potentially altering the immunological environment of the uterus and impacting subsequent fertility. The objective of the current study was to evaluate the immunological impact of lipopolysaccharide (LPS), as a model for potentially pathogenic bacteria, throughout the uterine endometrium between the luteal and follicular phase of the estrous cycle. Bovine uterine tracts were harvested in mid-luteal (n = 7) or follicular (n = 7) phase. Explants were collected from the contralateral and ipsilateral horn relative to the dominant follicle or corpus luteum, then subjected to one of three treatments: uncultured control, cultured control, or cultured with LPS (1 µg/mL). Explants underwent RNA extraction and targeted RNA sequencing for expression analyses of 40 immune response related genes. Sequencing reads were mapped to Bos taurus genome in CLC Genomics Workbench. Resulting total read counts were normalized by housekeeping gene GAPDH and analyzed for overall expression profile by Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) and Variable Importance in Projection (VIP) analyses in Metaboanalyst. Individual gene expression differences were determined by GLIMMIX procedure in SAS with fixed effects of treatment, estrous phase, uterine horn, and their interaction, with random effect of individual uterus. Expression of 29 genes were affected among treatment groups, with seven genes increased in LPS treatment compared to other groups (P < 0.05). Multiple genes were affected by estrous phase and uterine horn, independent of treatment (P < 0.05). The OPLS-DA analyses indicated overall gene expression differences due to clustering by estrous cycle and treatment (P < 0.001), with no effect of uterine horn (P > 0.10). Similar clustering was observed between luteal and follicular phase explants of controls, but distinct separate clustering between phases with LPS treatment (P = 0.001). According to VIP analyses, mucins were identified as contributing the most to differences observed between phase and treatment. In conclusion, estrous cycle phase resulted in differing overall endometrial gene expression profiles of immune response to LPS treatment. Therefore, altered immunological environment of the uterus in response to bacteria at different estrous cycle stages may lead to differences in reproductive success.

Regulations of Retinal Inflammation: Focusing on Müller Glia

Retinal inflammation underlies multiple prevalent retinal diseases. While microglia are one of the most studied cell types regarding retinal inflammation, growing evidence shows that Müller glia play critical roles in the regulation of retinal inflammation. Müller glia express various receptors for cytokines and release cytokines to regulate inflammation. Müller glia are part of the blood-retinal barrier and interact with microglia in the inflammatory responses. The unique metabolic features of Müller glia in the retina makes them vital for retinal homeostasis maintenance, regulating retinal inflammation by lipid metabolism, purine metabolism, iron metabolism, trophic factors, and antioxidants. miRNAs in Müller glia regulate inflammatory responses via different mechanisms and potentially regulate retinal regeneration. Novel therapies are explored targeting Müller glia for inflammatory retinal diseases treatment. Here we review new findings regarding the roles of Müller glia in retinal inflammation and discuss the related novel therapies for retinal diseases.

Engineered Bifunctional Proteins for Targeted Cancer Therapy: Prospects and Challenges

Bifunctional proteins (BFPs) are a class of therapeutic agents produced through genetic engineering and protein engineering, and are increasingly used to treat various human diseases, including cancer. These proteins usually have two or more biological functions-specifically recognizing different molecular targets to regulate the related signaling pathways, or mediating effector molecules/cells to kill tumor cells. Unlike conventional small-molecule or single-target drugs, BFPs possess stronger biological activity but lower systemic toxicity. Hence, BFPs are considered to offer many benefits for the treatment of heterogeneous tumors. In this review, the authors briefly describe the unique structural feature of BFP molecules and innovatively divide them into bispecific antibodies, cytokine-based BFPs (immunocytokines), and protein toxin-based BFPs (immunotoxins) according to their mode of action. In addition, the latest advances in the development of BFPs are discussed and the potential limitations or problems in clinical applications are outlined. Taken together, future studies need to be centered on understanding the characteristics of BFPs for optimizing and designing more effective such drugs.

The effects of protein level on cytokines and chemokines in the uterine environment of beef heifers during development

The development of replacement heifers is crucial for breeding success and herd efficiency. Nutritional management can affect not only reproductive development but also the inflammatory status of the uterine environment, which may impact reproductive functions such as pregnancy establishment and development. The study herein evaluated the concentration of cytokines and chemokines in the uterus of heifers supplemented with different levels of protein. Angus heifers (n = 60) were blocked by body weight (BW) and randomly assigned to 1 of 3 treatments based on protein supplementation level: control of 10% crude protein (CON), 20% crude protein (P20), or 40% crude protein (P40). BW, body condition score, and blood samples were taken every 2 wk for 140 d to monitor development. Uterine flushes were performed monthly and concentrations of cytokines (IL-1α, IL-1β, TNF-α, IFN-γ, IL-10, VEGF-α, IL-17A, and IL-36RA) and chemokines (IL-8, MCP-1, MIP-1α, and MIP-1β) were quantified via ELISA multiplex. To test if there were mean differences in cytokines between the treatment groups or over time, PROC GLIMMIX (SAS v 9.4) was utilized. Concentrations of all cytokines and chemokines, except IL-1α, changed throughout heifer development (P < 0.05). Heifers in the P40 treatment group displayed reduced concentrations of MCP-1 (P = 0.007) and tended to have decreased concentrations of IFN-γ (P = 0.06). Cytokine IL-36RA tended (P = 0.06) to be affected by protein level, with the lowest concentrations observed in CON heifers. Most cytokines and chemokines increased following the initial month of supplementation (P < 0.05). The increase in concentrations after 1 mo may indicate an adaptive response in the uterus to diet change. Cytokines and chemokines fluctuated due to physiological changes occurring during development. Further research is needed to determine the influence of nutrition on uterine inflammation and long-term impacts on reproductive function.

Emerging Mechanisms and Treatment Progress on Liver Metastasis of Colorectal Cancer

Colorectal cancer is currently the third largest malignant tumor in the world, with high new cases and high mortality. Metastasis is one of the most common causes of death of colorectal cancer, of which liver metastasis is the most fatal. Since the beginning of the Human Genome Project in 2001, people have gradually recognized the 3 billion base pairs that make up the human genome, of which only about 1.5% of the nucleic acid sequences are used for protein coding, including proto-oncogenes and tumor suppressor genes. A large number of differences in the expression of proto-oncogenes and tumor suppressor genes have also been found in the study of colorectal cancer, which proves that they are also actively involved in the progression of colorectal cancer and promote the occurrence of liver metastasis. Except for 1.5% of the coding sequence, the rest of the nucleic acid sequence does not encode any protein, which is called non-coding RNA. With the deepening of research, genome sequences without protein coding potential that were originally considered “junk sequences” may have important biological functions. Many years of studies have found that a large number of abnormal expression of ncRNA in colorectal cancer liver metastasis, indicating that ncRNA plays an important role in it. To explore the role and mechanism of these coding sequences and non-coding RNA in liver metastasis of colorectal cancer is very important for the early diagnosis and treatment of liver metastasis of colorectal cancer. This article reviews the coding genes and ncRNA that have been found in the study of liver metastasis of colorectal cancer in recent years, as well as the mechanisms that have been identified or are still under study, as well as the clinical treatment of liver metastasis of colorectal cancer.

Rat embryonic fibroblasts immortalized by MRPS18-2 protein are target for NK-cells

Overexpression of the human mitochondrial ribosomal protein MRPS18-2 (S18-2) led to immortalization of primary rat embryonic fibroblasts (REFs). The derived cells (18IM) expressed embryonic stem cell markers. Noteworthy, genes encoding the COX family proteins were up-regulated significantly. It is known that the COX family proteins are involved in the regulation of immune response. In the present work we demonstrate that 18IM cells behave like stem cells when subjected to directed differentiation in vitro. However, unlike stem cells, 18IM cells do not develop tumors in vivo, in SCID mice. This phenomenon is observed due to the strong natural killer (NK) cell immunogenicity. 18IM cells were better recognized by NK cells, compared with primary REFs, as was shown by a standard NK killing assay. Our data explain asymmetry in behavior of stem-like cells in vivo and in vitro, and this support the notion that stem and/or cancer-initiating cells are preferred targets for NK-cells. Concluding, the S18-2 protein is a putative target for cancer vaccines.

Targeted gene silencing of CCL2 inhibits triple negative breast cancer progression by blocking cancer stem cell renewal and M2 macrophage recruitment

Triple negative breast cancers are an aggressive subtype of breast cancer, characterized by the lack of estrogen receptor, progesterone receptor and Her2 expression. Triple negative breast cancers are non-responsive to conventional anti-hormonal and Her2 targeted therapies, making it necessary to identify new molecular targets for therapy. The chemokine CCL2 is overexpressed in invasive breast cancers, and regulates breast cancer progression through multiple mechanisms. With few approaches to target CCL2 activity, its value as a therapeutic target is unclear. In these studies, we developed a novel gene silencing approach that involves complexing siRNAs to TAT cell penetrating peptides (Ca-TAT) through non-covalent calcium cross-linking. Ca-TAT/siRNA complexes penetrated 3D collagen cultures of breast cancer cells and inhibited CCL2 expression more effectively than conventional antibody neutralization. Ca-TAT/siRNA complexes targeting CCL2 were delivered to mice bearing MDA-MB-231 breast tumor xenografts. In vivo CCL2 gene silencing inhibited primary tumor growth and metastasis, associated with a reduction in cancer stem cell renewal and recruitment of M2 macrophages. These studies are the first to demonstrate that targeting CCL2 expression in vivo may be a viable therapeutic approach to treating triple negative breast cancer.

Modulating the Innate Immune Response to Influenza A Virus: Potential Therapeutic Use of Anti-Inflammatory Drugs

Infection by influenza A viruses (IAV) is frequently characterized by robust inflammation that is usually more pronounced in the case of avian influenza. It is becoming clearer that the morbidity and pathogenesis caused by IAV are consequences of this inflammatory response, with several components of the innate immune system acting as the main players. It has been postulated that using a therapeutic approach to limit the innate immune response in combination with antiviral drugs has the potential to diminish symptoms and tissue damage caused by IAV infection. Indeed, some anti-inflammatory agents have been shown to be effective in animal models in reducing IAV pathology as a proof of principle. The main challenge in developing such therapies is to selectively modulate signaling pathways that contribute to lung injury while maintaining the ability of the host cells to mount an antiviral response to control virus replication. However, the dissection of those pathways is very complex given the numerous components regulated by the same factors (i.e., NF kappa B transcription factors) and the large number of players involved in this regulation, some of which may be undescribed or unknown. This article provides a comprehensive review of the current knowledge regarding the innate immune responses associated with tissue damage by IAV infection, the understanding of which is essential for the development of effective immunomodulatory drugs. Furthermore, we summarize the recent advances on the development and evaluation of such drugs as well as the lessons learned from those studies.

The CCL2 chemokine is a negative regulator of autophagy and necrosis in luminal B breast cancer cells

Luminal A and B breast cancers are the most prevalent forms of breast cancer diagnosed in women. Compared to luminal A breast cancer patients, patients with luminal B breast cancers experience increased disease recurrence and lower overall survival. The mechanisms that regulate the luminal B subtype remain poorly understood. The chemokine CCL2 is overexpressed in breast cancer, correlating with poor patient prognosis. The purpose of this study was to determine the role of CCL2 expression in luminal B breast cancer cells. Breast tissues, MMTV-PyVmT and MMTV-Neu transgenic mammary tumors forming luminal B-like lesions, were immunostained for CCL2 expression. To determine the role of CCL2 in breast cancer cells, CCL2 gene expression was silenced in mammary tumor tissues and cells using TAT cell-penetrating peptides non-covalently cross linked to siRNAs (Ca-TAT/siRNA). CCL2 expression was examined by ELISA and flow cytometry. Cell growth and survival were analyzed by flow cytometry, immunocytochemistry, and fluorescence microscopy. CCL2 expression was significantly increased in luminal B breast tumors, MMTV- PyVmT and MMTV-Neu mammary tumors, compared or normal breast tissue or luminal A breast tumors. Ca-TAT delivery of CCL2 siRNAs significantly reduced CCL2 expression in PyVmT mammary tumors, and decreased cell proliferation and survival. CCL2 gene silencing in PyVmT carcinoma cells or BT474 luminal B breast cancer cells decreased cell growth and viability associated with increased necrosis and autophagy. CCL2 expression is overexpressed in luminal B breast cancer cells and is important for regulating cell growth and survival by inhibiting necrosis and autophagy.

Pathway crosstalk analysis based on protein-protein network analysis in ovarian cancer

Ovarian cancer is the fifth leading cause of cancer death in women aged 35 to 74 years. Although there are several popular hypothesis of ovarian cancer pathogenesis, the genetic mechanisms are far from being clear. Recently, systems biology approaches such as network-based methods have been successfully applied to elucidate the mechanisms of diseases. In this study, we constructed a crosstalk network among ovarian cancer related pathways by integrating protein-protein interactions and KEGG pathway information. Several significant pathways were identified to crosstalk with each other in ovarian cancer, such as the chemokine, Notch, Wnt and NOD-like receptor signaling pathways. Results from these studies will provide the groundwork for a combination therapy approach targeting multiple pathways which will likely be more effective than targeting one pathway alone.

The possible diagnostic and prognostic use of systemic chemokine profiles in clinical medicine—the experience in acute myeloid leukemia from disease development and diagnosis via conventional chemotherapy to allogeneic stem cell transplantation

Chemokines are important regulators of many different biological processes, including (i) inflammation with activation and local recruitment of immunocompetent cells; (ii) angiogenesis as a part of inflammation or carcinogenesis; and (iii) as a bridge between the coagulation system and inflammation/immune activation. The systemic levels of various chemokines may therefore reflect local disease processes, and such variations may thereby be used in the routine clinical handling of patients. The experience from patients with myeloproliferative diseases, and especially patients with acute myeloid leukemia (AML), suggests that systemic plasma/serum cytokine profiles can be useful, both as a diagnostic tool and for prognostication of patients. However, cytokines/chemokines are released by a wide range of cells and are involved in a wide range of biological processes; the altered levels may therefore mainly reflect the strength and nature of the biological processes, and the optimal clinical use of chemokine/cytokine analyses may therefore require combination with organ-specific biomarkers. Chemokine levels are also altered by clinical procedures, therapeutic interventions and the general status of the patients. A careful standardization of sample collection is therefore important, and the interpretation of the observations will require that the overall clinical context is considered. Despite these limitations, we conclude that analysis of systemic chemokine/cytokine profiles can reflect important clinical characteristics and, therefore, is an important scientific tool that can be used as a part of future clinical studies to identify clinically relevant biomarkers.

Recent advances in obesity-induced inflammation and insulin resistance

It has been demonstrated in rodents and humans that chronic inflammation characterized by macrophage infiltration occurs mainly in adipose tissue or liver during obesity, in which activation of immune cells is closely associated with insulin sensitivity. Macrophages can be classified as classically activated (M1) macrophages that support microbicidal activity or alternatively activated (M2) macrophages that support allergic and antiparasitic responses. In the context of insulin action, M2 macrophages sustain insulin sensitivity by secreting IL-4 and IL-10, while M1 macrophages induce insulin resistance through the secretion of proinflammatory cytokines, such as TNFα. Polarization of M1/M2 is controlled by various dynamic functions of other immune cells. It has been demonstrated that, in a lean state, TH2 cells, Treg cells, natural killer T cells, or eosinophils contribute to the M2 activation of macrophages by secreting IL-4 or IL-10. In contrast, obesity causes alteration of the constituent immune cells, in which TH1 cells, B cells, neutrophils, or mast cells induce M1 activation of macrophages by the elevated secretion of TNFα and IFNγ. Increased secretion of TNFα and free fatty acids from hypertrophied adipocytes also contributes to the M1 activation of macrophages. Since obesity-induced insulin resistance is established by macrophage infiltration and the activation of immune cells inside tissues, identification of the factors that regulate accumulation and the intracellular signaling cascades that define polarization of M1/M2 would be indispensable. Regulation of these factors would lead to the pharmacological inhibition of obesity-induced insulin resistance. In this review, we introduce molecular mechanisms relevant to the pathophysiology and review the most recent studies of clinical applications targeting chronic inflammation.

Immunoproteomics: current technology and applications

The varied landscape of the adaptive immune response is determined by the peptides presented by immune cells, derived from viral or microbial pathogens or cancerous cells. The study of immune biomarkers or antigens is not new and classical methods such as agglutination, enzyme-linked immunosorbent assay, or Western blotting have been used for many years to study the immune response to vaccination or disease. However, in many of these traditional techniques, protein or peptide identification has often been the bottleneck. Recent advances in genomics and proteomics, has led to many of the rapid advances in proteomics approaches. Immunoproteomics describes a rapidly growing collection of approaches that have the common goal of identifying and measuring antigenic peptides or proteins. This includes gel based, array based, mass spectrometry, DNA based, or in silico approaches. Immunoproteomics is yielding an understanding of disease and disease progression, vaccine candidates, and biomarkers. This review gives an overview of immunoproteomics and closely related technologies that are used to define the full set of antigens targeted by the immune system during disease.

CXCL4-platelet factor 4, heparin-induced thrombocytopenia and cancer

Platelet factor 4 (CXCL4-PF4) is a chemokine that binds to and neutralizes heparin and other negatively charged proteoglycans, but is also involved in angiogenesis and cancer development. In some patients exposed to heparin, antibodies are generated against the CXCL-PF4/heparin complex that may activate platelets and coagulation and lead to thrombocytopenia and arterial or venous thrombosis, a condition commonly named heparin induced thrombocytopenia (HIT). HIT has been investigated in numerous clinical settings, but there is limited data on the epidemiology and phenotype of HIT in cancer patients. The present review describes the role of CXCL4-PF4 in cancer, the immunobiology, clinical presentation and diagnosis of HIT, and the specific problems faced in cancer patients.

High-dose etoposide in allogeneic stem cell transplantation

The anti-leukemic effect of etoposide is well documented. High-dose etoposide 60 mg/kg in combination with fractionated total body irradiation (TBI), usually single fractions of 1.2 Gy up to a total of 13.2 Gy, is used as conditioning therapy for allogeneic stem cell transplantation. Most studies of this conditioning regimen have included patients with acute leukemia receiving bone marrow or mobilized stem cell grafts derived from family or matched unrelated donors, and the treatment is then effective even in patients with high-risk disease. The most common adverse effects are fever with hypotension and rash, nausea and vomiting, sialoadenitis, neuropathy and metabolic acidosis. A small minority of patients develop severe allergic reactions. Etoposide has also been tested in a wide range of combination regimens, but for many of these combinations, relatively few patients are included, and some combinations have only been tested in patients who have undergone autologous transplants. However, the general conclusion is that many of these combinations are effective in patients with high-risk malignancies and the toxicity often seems acceptable. Thus, etoposide-based conditioning therapy should be further evaluated in patients having allogeneic transplants, but randomized trials are needed and the design of future trials should be based on the well-characterized TBI + high-dose etoposide regimen.

Future perspectives: should Th17 cells be considered as a possible therapeutic target in acute myeloid leukemia patients receiving allogeneic stem cell transplantation?

Th17 cells seem to promote proinflammatory effects, and their development seems to depend on intracellular signaling initiated by IL1β, supported by IL6 and IL23 and mediated by STAT3 and RORC2. Even though primary human AML cells may affect Th17 development through their constitutive cytokine release, the levels of circulating Th17 cells in older patients with untreated AML do not differ from healthy controls and show only minor variations during and following conventional intensive chemotherapy. IL17-A is the signature cytokine of Th17 cells, but in vitro studies have failed to demonstrate a direct antileukemic effect of IL17 on primary human AML cells for most patient samples. However, several observations suggest that Th17 cells mediate antileukemic effects through other mechanisms and are important in allogeneic stem cell transplantation. Firstly, genetic variants in IL23/Th17 pathway have a prognostic impact with regard to both development of GVHD and posttransplant infections. Secondly, circulating IL17-secreting cells are detected during early posttransplant pancytopenia, and their ability to release IL17 is associated with later GVHD. Thirdly, a high number of Th17 cells in allogeneic stem cell grafts are associated with later acute GVHD, levels of circulating Th17 cells are increased at the onset of acute GVHD, and these levels normalize during treatment. In the present article, we review previous studies of Th17 cells in AML and in the development of GVHD, possible therapeutic strategies and available therapeutic tools for targeting of Th17 cells.

Protein kinase R as mediator of the effects of interferon (IFN) gamma and tumor necrosis factor (TNF) alpha on normal and dysplastic hematopoiesis

IFNγ and TNFα are potent inhibitors of hematopoiesis and have been implicated in the pathophysiology of bone marrow failure and myelodysplastic syndromes (MDS). We examined the role of protein kinase R (PKR) in the generation of the inhibitory effects of these myelosuppressive cytokines on hematopoiesis. Our data demonstrate that PKR is rapidly phosphorylated/activated in response to engagement of IFNγ or TNFα receptors in normal human hematopoietic progenitors. Such engagement of PKR is important for the suppressive effects of these cytokines on normal hematopoiesis. Pharmacological targeting of PKR using a specific inhibitor or siRNA-mediated PKR knockdown results in partial reversal of the suppressive effects of IFNγ and TNFα on normal human CD34+-derived myeloid (colony-forming unit-granulocyte-monocytic) and erythroid (burst-forming unit-erythroid) progenitors. Importantly, inhibition of PKR activity or expression increases hematopoietic colony formation from human MDS progenitors, suggesting that drugs that target PKR may provide a novel approach for the treatment of MDS and marrow failure syndromes. Altogether, our data establish that beyond its key role in the induction of IFN-antiviral responses, PKR plays important roles in signaling for IFNγ and other myelosuppressive cytokine receptors as a common mediator of signals for hematopoietic suppression.

Clinical evaluation of cellular immunotherapy in acute myeloid leukaemia

Immunotherapy is currently under active investigation as an adjuvant therapy to improve the overall survival of patients with acute myeloid leukaemia (AML) by eliminating residual leukaemic cells following standard therapy. The graft-versus-leukaemia effect observed following allogeneic haematopoietic stem cell transplantation has already demonstrated the significant role of immune cells in controlling AML, paving the way to further exploitation of this effect in optimized immunotherapy protocols. In this review, we discuss the current state of cellular immunotherapy as adjuvant therapy for AML, with a particular focus on new strategies and recently published results of preclinical and clinical studies. Therapeutic vaccines that are being tested in AML include whole tumour cells as an autologous source of multiple leukaemia-associated antigens (LAA) and autologous dendritic cells loaded with LAA as effective antigen-presenting cells. Furthermore, adoptive transfer of cytotoxic T cells or natural killer cells is under active investigation. Results from phase I and II trials are promising and support further investigation into the potential of cellular immunotherapeutic strategies to prevent or fight relapse in AML patients.

Future perspectives: therapeutic targeting of notch signalling may become a strategy in patients receiving stem cell transplantation for hematologic malignancies

The human Notch system consists of 5 ligands and 4 membrane receptors with promiscuous ligand binding, and Notch-initiated signalling interacts with a wide range of other intracellular pathways. The receptor signalling seems important for regulation of normal and malignant hematopoiesis, development of the cellular immune system, and regulation of immune responses. Several Notch-targeting agents are now being developed, including natural receptor ligands, agonistic and antagonistic antibodies, and inhibitors of intracellular Notch-initiated signalling. Some of these agents are in clinical trials, and several therapeutic strategies seem possible in stem cell recipients: (i) agonists may be used for stem cell expansion and possibly to enhance posttransplant lymphoid reconstitution; (ii) receptor-specific agonists or antagonists can be used for immunomodulation; (iii) Notch targeting may have direct anticancer effects. Although the effects of therapeutic targeting are difficult to predict due to promiscuous ligand binding, targeting of this system may represent an opportunity to achieve combined effects with earlier posttransplant reconstitution, immunomodulation, or direct anticancer effects.

Combination of intensive chemotherapy and anticancer vaccines in the treatment of human malignancies: the hematological experience

In vitro studies have demonstrated that cancer-specific T cell cytotoxicity can be induced both ex vivo and in vivo, but this therapeutic strategy should probably be used as an integrated part of a cancer treatment regimen. Initial chemotherapy should be administered to reduce the cancer cell burden and disease-induced immune defects. This could be followed by autologous stem cell transplantation that is a safe procedure including both high-dose disease-directed chemotherapy and the possibility for ex vivo enrichment of the immunocompetent graft cells. The most intensive conventional chemotherapy and stem cell transplantation are used especially in the treatment of aggressive hematologic malignancies; both strategies induce T cell defects that may last for several months but cancer-specific T cell reactivity is maintained after both procedures. Enhancement of anticancer T cell cytotoxicity is possible but posttransplant vaccination therapy should probably be combined with optimalisation of immunoregulatory networks. Such combinatory regimens should be suitable for patients with aggressive hematological malignancies and probably also for other cancer patients.

Role of chemokines in the biology of natural killer cells

Natural killer (NK) cells represent a major subpopulation of lymphocytes. These cells have effector functions as they recognize and kill transformed cells as well as microbially infected cells. In addition, alloreactive NK cells have been successfully used to treat patients with acute myeloid leukemia and other hematological malignancies. NK cells are also endowed with immunoregulatory functions since they secrete cytokines such as IFN-γ, which favor the development of T helper 1 (Th1) cells, and chemokines such as CCL3/MIP-1α and CCL4/MIP-1β, which recruit various inflammatory cells into sites of inflammation. In human blood, NK cells are divided into CD56(bright) CD16(dim) and CD56(dim) CD16(bright) subsets. These subsets have different phenotypic expression and may have different functions; the former subset is more immunoregulatory and the latter is more cytolytic. The CD56(bright)CD16(dim) NK cells home into tissues such as the peripheral lymph nodes (LNs) under physiological conditions because they express the LN homing receptor CCR7 and they respond to CCL19/MIP-3β and CCL21/SLC chemokines. They also distribute into adenoid tissues or decidual uterus following the CXCR3/CXCL10 or CXCR4/CXCL12 axis. On the other hand, both NK cell subsets migrate into inflammatory sites, with more CD56(dim)CD16(bright) NK cells distributing into inflamed liver and lungs. CCR5/CCL5 axis plays an important role in the accumulation of NK cells in virally infected sites as well as during parasitic infections. CD56(bright)CD16(dim) cells also migrate into autoimmune sites such as inflamed synovial fluids in patients having rheumatoid arthritis facilitated by the CCR5/CCL3/CCL4/CCL5 axis, whereas they distribute into inflamed brains aided by the CX₃CR1/CX₃CL1 axis. On the other hand, CD56(dim)CD16(bright) NK cells accumulate in the liver of patients with primary biliary disease aided by the CXCR1/CXCL8 axis. However, the types of chemokines that contribute to their accumulation in target organs during graft vs. host (GvH) disease are not known. Further, chemokines activate NK cells to become highly cytolytic cells known as CC chemokine-activated killer (CHAK) cells that kill tumor cells. In summary, chemokines whether secreted in an autocrine or paracrine fashion regulate various biological functions of NK cells. Depending on the tissue and the chemokine secreted, NK cells may ameliorate the disease such as their roles in combating tumors or virally infected cells, and their therapeutic potentials in treating leukemias and other hematological malignancies, as well as reducing the incidence of GvH disease. In contrast, they may exacerbate the disease by damaging the affected tissues through direct cytotoxicity or by the release of multiple inflammatory cytokines and chemokines. Examples are their deleterious roles in autoimmune diseases such as rheumatoid arthritis and primary biliary cirrhosis.