Measurement of apoptosis, proliferation and three cytokines in 46 patients with myelodysplastic syndromes

Immune dysregulation and potential targeted therapy in myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematological diseases and a high risk for transformation to acute myeloid leukemia (AML). The identification of key genetic alterations in MDS has enhanced our understanding of the pathogenesis and evolution. In recent years, it has been found that both innate and adaptive immune signaling are activated in the hematopoietic niche of MDS with aberrant cytokine secretion in the bone marrow microenvironment. It is also clear that immune dysregulation plays an important role in the occurrence and progression of MDS, especially the destruction of the bone marrow microenvironment, including hematopoiesis and stromal components. The purpose of this review is to explore the role of immune cells, the immune microenvironment, and cytokines in the pathogenesis of MDS. Insights into the mechanisms of these variants may facilitate the development of novel effective treatments to prevent disease progression.

The value of serum IL-4 to predict the survival of MDS patients

BACKGROUND

Immune indicators are routinely used for the detection of myelodysplastic syndrome (MDS), but these are not utilized as a reference indicator to assess prognosis in MDS-related prognostic evaluation systems, such as the World Health Organizational prognostic scoring system, the international prostate symptom score, and the revised international prostate symptom score.

METHODS

We examined immune indicators, including cluster of differentiation (CD)3, CD4, CD8, CD56, CD19, interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor-a, and interferon-γ in 155 newly diagnosed MDS patients. We also conducted a correlation analysis with clinical indices.

RESULTS

IL-4 was found to be a predictor of survival in these 155 patients using the receiver operating characteristic curve, with 5.155 as the cut-off point. Patients with serum IL-4 levels ≥ 5.155 had a lower overall survival (OS) than those with IL-45.155 at diagnosis. Furthermore, multivariate analysis revealed that IL-4 levels > 5.155 were an independent predictor of OS (hazard ratio: 0.237; 95% confidence interval, 0.114-0.779; P = 0.013). In addition, serum IL-4 expression in the three different scoring systems showed significant differences in the survival of medium- to high-risk MDS patients (P = 0.014, P < 0.001, P < 0.001).

CONCLUSIONS

According to our study, IL-4 levels at the time of diagnosis can predict MDS prognosis in patients as a simple index reflecting host systemic immunity.

Plasmacytoid Dendritic Cells, a Novel Target in Myeloid Neoplasms

Plasmacytoid dendritic cells (pDC) are the main type I interferon producing cells in humans and are able to modulate innate and adaptive immune responses. Tumor infiltration by plasmacytoid dendritic cells is already well described and is associated with poor outcomes in cancers due to the tolerogenic activity of pDC. In hematological diseases, Blastic Plasmacytoid Dendritic Cells Neoplasm (BPDCN), aggressive leukemia derived from pDCs, is well described, but little is known about tumor infiltration by mature pDC described in Myeloid Neoplasms (MN). Recently, mature pDC proliferation (MPDCP) has been described as a differential diagnosis of BPDCN associated with acute myeloid leukemia (pDC-AML), myelodysplastic syndrome (pDC-MDS) and chronic myelomonocytic leukemia (pDC-CMML). Tumor cells are myeloid blasts and/or mature myeloid cells from related myeloid disorders and pDC derived from a clonal proliferation. The poor prognosis associated with MPDCP requires a better understanding of pDC biology, MN oncogenesis and immune response. This review provides a comprehensive overview about the biological aspects of pDCs, the description of pDC proliferation in MN, and an insight into putative therapies in pDC-AML regarding personalized medicine.

Microenvironmental Features Driving Immune Evasion in Myelodysplastic Syndromes and Acute Myeloid Leukemia

Bone marrow, besides the known functions of hematopoiesis, is an active organ of the immune system, functioning as a sanctuary for several mature immune cells. Moreover, evidence suggests that hematopoietic stem cells (the bone marrow’s functional unit) are capable of directly sensing and responding to an array of exogenous stimuli. This chronic immune stimulation is harmful to normal hematopoietic stem cells, while essential for the propagation of myeloid diseases, which show a dysregulated immune microenvironment. The bone marrow microenvironment in myelodysplastic syndromes (MDS) is characterized by chronic inflammatory activity and immune dysfunction, that drive excessive cellular death and through immune evasion assist in cancer cell expansion. Acute myeloid leukemia (AML) is another example of immune response failure, with features that augment immune evasion and suppression. In this review, we will outline some of the functions of the bone marrow with immunological significance and describe the alterations in the immune landscape of MDS and AML that drive disease progression.

Effect of 5-Azacitidine Treatment on Redox Status and Inflammatory Condition in MDS Patients

This study focused on the impact of the treatment with the hypomethylating agent 5-azacitidine on the redox status and inflammation in 24 MDS patients. Clinical and genetic features of MDS patients were recorded, and peripheral blood samples were used to determine the activity of the endogenous antioxidant defense system (superoxide dismutase, SOD; catalase, CAT; glutathion peroxidase, GPx; and reductase, GRd, activities), markers of oxidative damage (lipid peroxidation, LPO, and advanced oxidation protein products, AOPP). Moreover, pro-inflammatory cytokines and plasma nitrite plus nitrate levels as markers of inflammation, as well as CoQ10 plasma levels, were also measured. Globally, MDS patients showed less redox status in terms of a reduction in the GSSG/GSH ratio and in the LPO levels, as well as increased CAT activity compared with healthy subjects, with no changes in SOD, GPx, and GRd activities, or AOPP levels. When analyzing the evolution from early to advanced stages of the disease, we found that the GPx activity, GSSG/GSH ratio, LPO, and AOPP increased, with a reduction in CAT. GPx changes were related to the presence of risk factors such as high-risk IPSS-R or mutational score. Moreover, there was an increase in IL-2, IL-6, IL-8, and TNF-α plasma levels, with a further increase of IL-2 and IL-10 from early to advanced stages of the disease. However, we did not observe any association between inflammation and oxidative stress. Finally, 5-azacitidine treatment generated oxidative stress in MDS patients, without affecting inflammation levels, suggesting that oxidative status and inflammation are two independent processes.

From Immune Dysregulations to Therapeutic Perspectives in Myelodysplastic Syndromes: A Review

The pathophysiology of myelodysplastic syndromes (MDSs) is complex and often includes immune dysregulation of both the innate and adaptive immune systems. Whereas clonal selection mainly involves smoldering inflammation, a cellular immunity dysfunction leads to increased apoptosis and blast proliferation. Addressing immune dysregulations in MDS is a recent concept that has allowed the identification of new therapeutic targets. Several approaches targeting the different actors of the immune system have therefore been developed. However, the results are very heterogeneous, indicating the need to improve our understanding of the disease and interactions between chronic inflammation, adaptive dysfunction, and somatic mutations. This review highlights current knowledge of the role of immune dysregulation in MDS pathophysiology and the field of new drugs.

Programmed necroptosis is upregulated in low-grade myelodysplastic syndromes and may play a role in the pathogenesis

Myelodysplastic syndrome (MDS) is characterized by persistent cytopenias and evidence of morphologic dysplasia in the bone marrow (BM). Excessive hematopoietic programmed cell death (PCD) and inflammation have been observed in the bone marrow of patients with MDS, and are thought to play a significant role in the pathogenesis of the disease. Necroptosis is a major pathway of PCD that incites inflammation; however, the role of necroptosis in human MDS has not been extensively investigated. To assess PCD status in newly diagnosed MDS, we performed immunofluorescence staining with computational image analysis of formalin-fixed, paraffin-embedded BM core biopsies using cleaved caspase-3 (apoptosis marker) and necroptosis markers (receptor-interacting serine/threonine-protein kinase 1 [RIPK1], phospho-mixed lineage kinase domain-like protein [pMLKL]). Patients with MDS, but not controls without MDS or patients with de novo acute myeloid leukemia, had significantly increased expression of RIPK1 and pMLKL but not cleaved caspase-3, which was most evident in morphologically low-grade MDS (<5% BM blasts) and in MDS with low International Prognostic Scoring System risk score. RIPK1 expression highly correlated with the distribution of CD71⁺ erythroid precursors but not with CD34⁺ blast cells. We found that necroptosis is upregulated in early/low-grade MDS relative to control participants, warranting further study to define the role of necroptosis in the pathogenesis of MDS and as a potential biomarker for the diagnosis of low-grade MDS.

Therapeutic targeting of the inflammasome in myeloid malignancies

Even though genetic perturbations and mutations are important for the development of myeloid malignancies, the effects of an inflammatory microenvironment are a critical modulator of carcinogenesis. Activation of the innate immune system through various ligands and signaling pathways is an important driver of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). The DAMPs, or alarmins, which activate the inflammasome pathway via the TLR4/NLR signaling cascade causes the lytic cell death of hematopoietic stem and progenitor cells (HSPCs), ineffective hematopoiesis, and β-catenin-induced proliferation of cancer cells, leading to the development of MDS/AML phenotype. It is also associated with other myeloid malignancies and involved in the pathogenesis of associated cytopenias. Ongoing research suggests the interplay of inflammasome mediators with immune modulators and transcription factors to have a significant role in the development of myeloid diseases, and possibly therapy resistance. This review discusses the role and importance of inflammasomes and immune pathways in myeloid malignancies, particularly MDS/AML, to better understand the disease pathophysiology and decipher the scope of therapeutic interventions.

Myelodysplastic Syndromes in the Postgenomic Era and Future Perspectives for Precision Medicine

Simple Summary

With demographic ageing, improved cancer survivorship and increased diagnostic sensitivity, incident cases of patients with Myelodysplastic Syndromes (MDS) are continuously rising, leading to a relevant impact on health care resources. Disease heterogeneity and various comorbidities are challenges for the management of the generally elderly patients. Therefore, experienced physicians and multidisciplinary teams should be involved in the establishment of the correct diagnosis, risk-assessment and personalized treatment plan. Next-generation sequencing allows for early detection of clonal hematopoiesis and monitoring of clonal evolution, but also poses new challenges for its appropriate use. At present, allogeneic hematopoietic stem cell transplantation remains the only curative treatment option for a minority of fit MDS patients. All others receive palliative treatment and will eventually progress, having an unmet need for novel therapies. Targeting compounds are in prospect for precision medicine, however, abrogation of clonal evolution to acute myeloid leukemia remains actually out of reach.

Abstract

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal disorders caused by sequential accumulation of somatic driver mutations in hematopoietic stem and progenitor cells (HSPCs). MDS is characterized by ineffective hematopoiesis with cytopenia, dysplasia, inflammation, and a variable risk of transformation into secondary acute myeloid leukemia. The advent of next-generation sequencing has revolutionized our understanding of the genetic basis of the disease. Nevertheless, the biology of clonal evolution remains poorly understood, and the stochastic genetic drift with sequential accumulation of genetic hits in HSPCs is individual, highly dynamic and hardly predictable. These continuously moving genetic targets pose substantial challenges for the implementation of precision medicine, which aims to maximize efficacy with minimal toxicity of treatments. In the current postgenomic era, allogeneic hematopoietic stem cell transplantation remains the only curative option for younger and fit MDS patients. For all unfit patients, regeneration of HSPCs stays out of reach and all available therapies remain palliative, which will eventually lead to refractoriness and progression. In this review, we summarize the recent advances in our understanding of MDS pathophysiology and its impact on diagnosis, risk-assessment and disease monitoring. Moreover, we present ongoing clinical trials with targeting compounds and highlight future perspectives for precision medicine.

Inflammation, Aging and Hematopoiesis: A Complex Relationship

All vertebrate blood cells descend from multipotent hematopoietic stem cells (HSCs), whose activity and differentiation depend on a complex and incompletely understood relationship with inflammatory signals. Although homeostatic levels of inflammatory signaling play an intricate role in HSC maintenance, activation, proliferation, and differentiation, acute or chronic exposure to inflammation can have deleterious effects on HSC function and self-renewal capacity, and bias their differentiation program. Increased levels of inflammatory signaling are observed during aging, affecting HSCs either directly or indirectly via the bone marrow niche and contributing to their loss of self-renewal capacity, diminished overall functionality, and myeloid differentiation skewing. These changes can have significant pathological consequences. Here, we provide an overview of the current literature on the complex interplay between HSCs and inflammatory signaling, and how this relationship contributes to age-related phenotypes. Understanding the mechanisms and outcomes of this interaction during different life stages will have significant implications in the modulation and restoration of the hematopoietic system in human disease, recovery from cancer and chemotherapeutic treatments, stem cell transplantation, and aging.

The inflammatory cytokine profile of myelodysplastic syndromes: A meta-analysis

BACKGROUND

Accumulating evidence has indicated that the dysregulation of immunological environment has an important role in the pathogenesis of myelodysplastic syndromes (MDS). The previous studies about the levels of the inflammatory cytokines in MDS, such as TNF-α, IFN-γ, IL-6, IL-8, and IL-17, have yielded controversial results. Thus, we performed a meta-analysis to assess the levels of these inflammatory cytokines in MDS.

METHODS

A systematic search in PubMed, MEDLINE, Cochrane Library, Web of Science, CNKI, and CBM was conducted to find eligible studies. Meta-analyses were performed using STATA 12.0 for Windows. Heterogeneity between included studies was assessed by I test. We chose SMD as the summary statistic.

RESULTS

A total of 697 individuals from 11 studies were included in this study. Our results suggest the levels of TNF-α, IL-6, IL-8 were significantly higher in MDS patients compared with controls, SMD and 95%CI was 1.48 (0.60, 2.36), 0.71 (0.16, 1.25) and 0.69 (0.28, 1.09), respectively. Moreover, the levels of IL-17 have decreased in the high-risk MDS, the SMD and 95% CI was 2.96 (0.78, 5.15).

CONCLUSION

A close association between immunological microenvironment disorders and the pathogenesis of MDS was revealed in this meta-analysis. More importantly, the profiles of inflammatory cytokines appear to change along the progression of the disease.

Disordered Immune Regulation and its Therapeutic Targeting in Myelodysplastic Syndromes

PURPOSE OF REVIEW

Immune dysregulation is a defining feature of myelodysplastic syndromes (MDS). Recently, several studies have further defined the complex role of immune alterations within MDS. Herein, we will summarize some of these findings and discuss the therapeutic strategies currently in development.

RECENT FINDINGS

Immune alterations in MDS are complex, heterogeneous, and intertwined with clonal hematopoiesis and stromal cell dysfunction. Inflammation in MDS proceeds as a vicious cycle, mediated in large part by secreted factors, which induce cell death and activate innate immune signaling. Therapeutic targeting of this variable immune dysregulation has led to modest responses thus far, but incorporation of the growing repertoire of immunotherapy brings new potential for improved outcomes. The immune milieu is variable across the spectrum of MDS subtypes, with a changing balance of inflammatory and suppressive cellular forces from low- to high-risk disease.

Increased Regulatory T Cells in Peripheral Blood of Acute Myeloid Leukemia Patients Rely on Tumor Necrosis Factor (TNF)-α-TNF Receptor-2 Pathway

Acute myeloid leukemia (AML) harbors an immune suppression environment, featured by increased regulatory T cells (Tregs). The expression of tumor necrosis factor receptor-2 (TNFR2) on Tregs could be used to identify the maximally suppressive Treg population, and TNF-α furtherly promoted the expansion and function of Tregs via TNFR2 in mice. However, the role of TNF-α has not been determined in AML patients. In view of high levels of TNF-α and Tregs in AML patients, we hypothesized that the increased frequency of Tregs may rely on TNF-α–TNFR2 pathway. We investigated the levels of TNFR2⁺ Tregs and TNF-α secreted by T cells in peripheral blood (PB) of AML by flow cytometry and enzyme-linked immunosorbent assay, respectively. Our results showed the elevated plasma TNF-α in PB of newly diagnosed (ND) AML patients. The production of TNF-α by CD4⁺ T cells, especially by T helper (Th)17 cells was remarkably higher in ND AML patients than in complete remission (CR) patients and healthy controls. Then, we found that the circulating frequencies of CD4⁺CD25⁺ Tregs and CD4⁺CD25^high Tregs in AML patients were elevated compared with those in healthy controls and CR patients. TNFR2 expression was much higher on Tregs in AML patients and was preferentially expressed on CD4⁺CD25^high T cells. Furthermore, we confirmed that, in vitro, the additional TNF-α can increase the frequency of Tregs through TNFR2 in both AML patients and healthy controls. Summarily, in AML patients, the abnormally elevated level of TNF-α secreted by CD4⁺ T especially Th17 cells promoted the higher Tregs frequency via the TNF-α–TNFR2 pathway.

Shanghai Health Study (2001-2009): What was learned about benzene health effects?

The Shanghai Health Study (SHS) was a large epidemiology study conducted as a joint effort between the University of Colorado and Fudan University in Shanghai, China. The study was funded by members of the American Petroleum Institute between 2001 and 2009 and was designed to evaluate the human health effects associated with benzene exposure. Two arms of the SHS included: an occupational-based molecular epidemiology study and several hospital-based case control studies. Consistent with historical literature, following sufficient exposure to relatively high airborne concentrations and years of exposure, the SHS concluded that exposure to benzene resulted in an increased risk of various blood and bone marrow abnormalities such as benzene poisoning, aplastic anemia (AA), myelodysplastic syndrome (MDS), and acute myeloid leukemia (AML). Non-Hodgkin lymphoma (NHL) was not significantly increased for the exposures examined in this study. Perhaps the most important contribution of the SHS was furthering our understanding of the mechanism of benzene-induced bone marrow toxicity and the importance of identifying the proper subset of MDS relevant to benzene. Investigators found that benzene-exposed workers exhibited bone marrow morphology consistent with an immune-mediated inflammatory response. Contrary to historic reports, no consistent pattern of cytogenetic abnormalities was identified in these workers. Taken together, findings from SHS provided evidence that the mechanism for benzene-induced bone marrow damage was not initiated by chromosome abnormalities. Instead, chronic inflammation, followed by an immune-mediated response, is likely to play a more significant role in benzene-induced disease initiation and progression than previously thought.

Hematopathological alterations of major tumor suppressor cascade, vital cell cycle inhibitors and hematopoietic niche components in experimental myelodysplasia

Myelodysplastic syndrome (MDS) is a poorly understood dreadful hematopoietic disorder that involves maturational defect and abnormalities in blood cell production leading to dysplastic changes and peripheral blood pancytopenia. The present work aims in establishing the mechanistic relationship of the expressional alterations of major tumor suppressor cascade, vital cell cycle inhibitors and hematopoietic microenvironmental components with the disease pathophysiologies. The study involves the development of N-N' Ethylnitrosourea (ENU) induced mouse model of MDS, characterization of the disease with blood film and bone marrow smear studies, scanning electron microscopic observation, mitochondrial membrane potential determination, flowcytometric analysis of osteoblastic and vascular niche components along with the expressional study of cleaved caspase-3, PCNA, Chk-2, p53, Ndn, Gfi-1, Tie-2, Sdf-1, Gsk-3β, p18 and Myt-1 in the bone marrow compartment. Dysplastic features were found in peripheral blood of MDS mice which seemed to be the consequence of three marrow pathophysiological conditions viz; aberrant rise of cellular proliferation, increased apoptosis and crowding of abnormal blast population. Expressional decline of the p53 cascade involving Chk-2, p53, Ndn, Gfi-1 along with the downregulation of major cell cycle inhibitors seemed to be associated with the hyper-proliferative nature of bone marrow cells during MDS. Moreover the disruption of osteoblastic niche components added to the decreased hematopoietic quiescency. Increased marrow vascular niche components signified the pre-malignant state of MDS. Elevated cellular apoptosis and rise in the blast burden were also found to be associated with the p53 expression dependent collapsing of mitochondrial membrane potential and upregulation of Tie-2 respectively. The study established the mechanistic correlation between the alterations of the mentioned signaling components and hematopoietic anomalies during MDS which may be beneficial for the development of therapeutic strategies for the disease.

Beyond the Niche: Myelodysplastic Syndrome Topobiology in the Laboratory and in the Clinic

We review the murine and human microenvironment and hematopoietic stem cell niche in the context of intact bone marrow architecture in man and mouse, both in normal and in myelodysplastic syndrome marrow. We propose that the complexity of the hematopoietic stem cell niche can usefully be approached in the context of its topobiology, and we provide a model that incorporates in vitro and in vivo models as well as in situ findings from intact human marrow to explain the changes seen in myelodysplastic syndrome patients. We highlight the clinical application of the study of the bone marrow microenvironment and its topobiology in myelodysplastic syndromes.

Deregulation of innate immune and inflammatory signaling in myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are a group of heterogeneous clonal hematologic malignancies that are characterized by defective bone marrow (BM) hematopoiesis and by the occurrence of intramedullary apoptosis. During the past decade, the identification of key genetic and epigenetic alterations in patients has improved our understanding of the pathophysiology of this disease. However, the specific molecular mechanisms leading to the pathogenesis of MDS have largely remained obscure. Recently, essential evidence supporting the direct role of innate immune abnormalities in MDS has been obtained, including the identification of multiple key regulators that are overexpressed or constitutively activated in BM hematopoietic stem and progenitor cells. Mounting experimental results indicate that the dysregulation of these molecules leads to abnormal hematopoiesis, unbalanced cell death and proliferation in patients' BM, and has an important role in the pathogenesis of MDS. Furthermore, there is compelling evidence that the deregulation of innate immune and inflammatory signaling also affects other cells from the immune system and the BM microenvironment, which establish aberrant associations with hematopoietic precursors and contribute to the MDS phenotype. Therefore, the deregulation of innate immune and inflammatory signaling should be considered as one of the driving forces in the pathogenesis of MDS. In this article, we review and update the advances in this field, summarizing the results from the most recent studies and discussing their clinical implications.

Mesenchymal stem cells in pathogenesis of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are clonal malignant stem cell disorders characterized by inefficient hematopoiesis. The role of the marrow microenvironment in the pathogenesis of the disease has been controversial. Emerging evidence indicated that mesenchymal stem cells (MSC) derived from MDS patients were cytogenetically abnormal, and they showed a deficient hematopoietic-supportive capacity and increased production of cytokine such as tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interferon γ (IFN-γ). From the point of some evidence, the abnormal microenvironment seems to participate in the progression of the disease by contributing to the selective expansion of the malignant clone. In this review, we will discuss the most recent progress related to identification of normal MSC and the importance of the stem cell niche in development and maintenance of MDS.

Mitoquinone restores platelet production in irradiation-induced thrombocytopenia

Myelodysplastic syndromes (MDS) are hallmarked by cytopenia and dysplasia of hematopoietic cells, often accompanied by mitochondrial dysfunction and increases of reactive oxygen species (ROS) within affected cells. However, it is not known whether the increase in ROS production is an instigator or a byproduct of the disease. The present investigation shows that mice lacking immediate early responsive gene X-1 (IEX-1) exhibit lineage specific increases in ROS production and abnormal cytology upon radiation in blood cell types commonly identified in MDS. These affected cell lineages chiefly have the bone marrow as a primary site of differentiation and maturation, while cells with extramedullary differentiation and maturation like B- and T-cells remain unaffected. Increased ROS production is likely to contribute significantly to irradiation-induced thrombocytopenia in the absence of IEX-1 as demonstrated by effective reversal of the disorder after mitoquinone (MitoQ) treatment, a mitochondria-specific antioxidant. MitoQ reduced intracellular ROS production within megakaryocytes and platelets. It also normalized mitochondrial membrane potential and superoxide production in platelets in irradiated, IEX-1 deficient mice. The lineage-specific effects of mitochondrial ROS may help us understand the etiology of thrombocytopenia in association with MDS in a subgroup of the patients.

Acquired myelodysplasia or myelodysplastic syndrome: clearing the fog

Myelodysplastic syndromes (MDS) are clonal myeloid disorders characterized by progressive peripheral blood cytopenias associated with ineffective myelopoiesis. They are typically considered neoplasms because of frequent genetic aberrations and patient-limited survival with progression to acute myeloid leukemia (AML) or death related to the consequences of bone marrow failure including infection, hemorrhage, and iron overload. A progression to AML has always been recognized among the myeloproliferative disorders (MPD) but occurs only rarely among those with essential thrombocythemia (ET). Yet, the World Health Organization (WHO) has chosen to apply the designation myeloproliferative neoplasms (MPN), for all MPD but has not similarly recommended that all MDS become the myelodysplastic neoplasms (MDN). This apparent dichotomy may reflect the extremely diverse nature of MDS. Moreover, the term MDS is occasionally inappropriately applied to hematologic disorders associated with acquired morphologic myelodysplastic features which may rather represent potentially reversible hematological responses to immune-mediated factors, nutritional deficiency states, and disordered myelopoietic responses to various pharmaceutical, herbal, or other potentially myelotoxic compounds. We emphasize the clinical settings, and the histopathologic features, of such AMD that should trigger a search for a reversible underlying condition that may be nonneoplastic and not MDS.

Bone marrow injury induced via oxidative stress in mice by inhalation exposure to formaldehyde

OBJECTIVE

Formaldehyde, a ubiquitous environmental pollutant has been classified as a human leukemogen. However, toxicity of formaldehyde in bone marrow, the target site of leukemia induction, is still poorly understood.

METHODOLOGY/PRINCIPAL FINDINGS

To investigate bone marrow toxicity (bone marrow pathology, hematotoxicity) and underlying mechanisms (oxidative stress, inflammation, apoptosis) in formaldehyde-exposed mice. Male Balb/c mice were exposed to formaldehyde (0, 0.5, and 3.0 mg/m(3)) by nose-only inhalation for 8 hours/day, over a two week period designed to simulate a factory work schedule, with an exposure-free "weekend" on days 6 and 7, and were sacrificed on the morning of day 13. Counts of white blood cells, red blood cells and lymphocytes were significantly (p<0.05) decreased at 0.5 mg/m(3) (43%, 7%, and 39%, respectively) and 3.0 mg/m(3) (52%, 27%, and 43%, respectively) formaldehyde exposure, while platelet counts were significantly increased by 109% (0.5 mg/m(3)) and 67% (3.0 mg/m(3)). Biomarkers of oxidative stress (reactive oxygen species, glutathione depletion, cytochrome P450 1A1 and glutathione s-transferase theta 1 expression), inflammation (nuclear factor kappa-B, tomour necrosis factor alpha, interleukin-1 beta), and apoptosis (activity of cysteine-aspartic acid protease 3) in bone marrow tissues were induced at one or both formaldehyde doses mentioned above.

CONCLUSIONS/SIGNIFICANCE

Exposure of mice to formaldehyde by inhalation induced bone marrow toxicity, and that oxidative stress, inflammation and the consequential apoptosis jointly constitute potential mechanisms of such induced toxicity.

STAT3 mutations indicate the presence of subclinical T-cell clones in a subset of aplastic anemia and myelodysplastic syndrome patients

Large granular lymphocyte leukemia (LGL) is often associated with immune cytopenias and can cooccur in the context of aplastic anemia (AA) and myelodysplastic syndromes (MDS). We took advantage of the recent description of signal transducer and activator of transcription 3 (STAT3) mutations in LGL clonal expansions to test, using sensitive methods, for the presence of these mutations in a large cohort of 367 MDS and 140 AA cases. STAT3 clones can be found not only in known LGL concomitant cases, but in a small proportion of unsuspected ones (7% AA and 2.5% MDS). In STAT3-mutated AA patients, an interesting trend toward better responses of immunosuppressive therapy and an association with the presence of human leukocyte antigen-DR15 were found. MDSs harboring a STAT3 mutant clone showed a lower degree of bone marrow cellularity and a higher frequency of developing chromosome 7 abnormalities. STAT3-mutant LGL clones may facilitate a persistently dysregulated autoimmune activation, responsible for the primary induction of bone marrow failure in a subset of AA and MDS patients.

Hematopoietic stem cell and progenitor cell mechanisms in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of disorders characterized by variable cytopenias and ineffective hematopoiesis. Hematopoietic stem cells (HSCs) and myeloid progenitors in MDS have not been extensively characterized. We transplanted purified human HSCs from MDS samples into immunodeficient mice and show that HSCs are the disease-initiating cells in MDS. We identify a recurrent loss of granulocyte-macrophage progenitors (GMPs) in the bone marrow of low risk MDS patients that can distinguish low risk MDS from clinical mimics, thus providing a simple diagnostic tool. The loss of GMPs is likely due to increased apoptosis and increased phagocytosis, the latter due to the up-regulation of cell surface calreticulin, a prophagocytic marker. Blocking calreticulin on low risk MDS myeloid progenitors rescues them from phagocytosis in vitro. However, in the high-risk refractory anemia with excess blasts (RAEB) stages of MDS, the GMP population is increased in frequency compared with normal, and myeloid progenitors evade phagocytosis due to up-regulation of CD47, an antiphagocytic marker. Blocking CD47 leads to the selective phagocytosis of this population. We propose that MDS HSCs compete with normal HSCs in the patients by increasing their frequency at the expense of normal hematopoiesis, that the loss of MDS myeloid progenitors by programmed cell death and programmed cell removal are, in part, responsible for the cytopenias, and that up-regulation of the "don't eat me" signal CD47 on MDS myeloid progenitors is an important transition step leading from low risk MDS to high risk MDS and, possibly, to acute myeloid leukemia.

Emerging immunosuppressive drugs in myelodysplastic syndromes

INTRODUCTION

Myelodysplastic syndromes (MDS) are characterized by dysplastic morphologic features and ineffective hematopoiesis. Pathophysiological characteristics change over time making therapeutic development a major challenge. In early MDS, cytopenias arise or are exacerbated by humoral and cellular immune-mediators that suppress hematopoietic progenitor survival and alter the bone marrow microenvironment.

AREAS COVERED

In this review, current immunosuppressive regimens are described. To identify new therapies that may enhance immunosuppressive therapy (IST) response and identify pharmacodynamic biomarkers for patient selection, the inflammasome, cytokines, metabolic pathways and signaling events are described.

EXPERT OPINION

Agents with the potential to induce early, durable hematologic remissions are needed and many new immunosuppressive agents are available for investigation. An immune-mediated mechanism is likely to contribute to MDS early after diagnosis. New approaches that interfere with inflammatory pathways in the bone marrow microenvironment may move closer toward sustained disease control in MDS.

Refractory sweet syndrome with autoimmune organizing pneumonia treated with monoclonal antibodies to tumor necrosis factor

We describe a 54-year-old man with highly refractory Sweet syndrome associated with autoimmune multifocal organizing pneumonia and underlying myelodysplastic disorder. His lung disease responded to oral cyclophosphamide. However, his skin disease and systemic symptoms followed a chronic course and responded only to very high doses of corticosteroid and were refractory to a number of corticosteroid-sparing agents. He was ultimately treated with infliximab, resulting in remission of his cutaneous and systemic symptoms and successful tapering of his corticosteroid dose. Subsequently, infliximab was replaced with adalimumab to achieve more sustained remission. His pulmonary lesions have not recurred on this treatment. His myelodysplastic syndrome followed a very slowly progressive course consistent with refractory anemia. This case report demonstrates the effectiveness of treatment with monoclonal antibody specific for tumor necrosis factor alpha (TNFalpha) in a patient with severe manifestations of Sweet syndrome refractory to other treatments.

Immunologic aspects of hypoplastic myelodysplastic syndrome

The pathophysiology of myelodysplastic syndromes (MDS) is multiple, complex, and poorly understood. In some cases of MDS, especially those in which the bone marrow is hypocellular, there is increasing experimental and clinical indication that an immune-mediated damage to hematopoietic precursors and changes in the hematopoiesis-supporting microenvironment contribute to disease development. Increased serum levels of type-1 cytokines, tumor necrosis factor-α (TNF-α), and interferon-γ (INF-γ), and oligoclonal expansion of cytotoxic T cells are observed in human MDS. In some cases, the immunologic attack to the marrow appears to be triggered by MDS-specific antigens, damaging the microenvironment and inducing cell apoptosis especially of normal progenitors. In murine models, dysregulation of osteoprogenitors leads to disrupted hematopoiesis of healthy hematopoietic progenitor and stem cells, eventually resulting in MDS and leukemia. In hypocellular MDS, marrow failure appears to be not only the result of ineffective erythropoiesis of abnormal clones, but also due to inhibition of normal progenitors. Immunosuppressive therapy with cyclosporine, anti-thymocyte globulin, or alemtuzumab may alleviate cytopenias and in some instances induce cytogenetic remission. However, not all patients respond to immunosuppression, and the identification of relevant biomarkers for an immune mechanism is necessary to identify those patients who may benefit from this treatment modality.

IPSS-independent prognostic value of plasma CXCL10, IL-7 and IL-6 levels in myelodysplastic syndromes

Recent studies suggest a powerful prognostic value for plasma cytokine levels in primary myelofibrosis (interleukin (IL)-2R, IL-8, IL-12, IL-15 and C–X–C motif chemokine 10 (CXCL10)) and large-cell lymphoma (IL-2R, IL-8, IL-10, IL-12, CXCL9 and CXCL10). To examine the possibility of a similar phenomenon in myelodysplastic syndromes (MDS), we used multiplex enzyme-linked immunosorbent assay to measure 30 plasma cytokines in 78 patients with primary MDS. Compared with normal controls (n=35), the levels of 19 cytokines were significantly altered. Multivariable analysis identified increased levels of CXCL10 (P<0.01), IL-7 (P=0.02) and IL-6 (P=0.07) as predictors of shortened survival; the survival association remained significant when the Cox model was adjusted for the International Prognostic Scoring System, age, transfusion-need or thrombocytopenia. MDS patients with normal plasma levels of CXCL10, IL-7 and IL-6 lived significantly longer (median survival 76 months) than those with elevated levels of at least one of the three cytokines (median survival 25 months) (P<0.01). Increased levels of IL-6 were associated with inferior leukemia-free survival, independent of other prognostic factors (P=0.01). Comparison of plasma cytokines between MDS (n=78) and primary myelofibrosis (n=127) revealed a significantly different pattern of abnormalities. These observations reinforce the concept of distinct and prognostically relevant plasma cytokine signatures in hematological malignancies.

Association of tumour necrosis factor-alpha -308 G/A polymorphism with primary open-angle glaucoma

BACKGROUND

Tumour necrosis factor-alpha (TNF-α) is an important proinflammatory cytokine driving axonal degeneration and retinal ganglion cell apoptosis in glaucoma. The aim of the study was to evaluate the association of TNF-α -308 G/A and -238 G/A polymorphisms with primary open-angle glaucoma (POAG).

DESIGN

A prospective, case-control study, university hospital setting.

PARTICIPANTS

Eighty-six POAG patients and 193 healthy unrelated controls.

METHODS

TNF-α polymorphisms were screened by using direct gene sequencing.

MAIN OUTCOME MEASURES

Frequency of TNF-α -308 G/A and TNF-α -238 G/A promoter polymorphisms in glaucoma and healthy subjects.

RESULTS

The frequencies of TNF-α -308 GA genotype and 'A' allele were higher in patients with POAG (22.1% and 12.2%, respectively) in comparison with the control group (10.9% and 6%, respectively) (P = 0.046 and 0.02, respectively), with odds ratios of 2.45 (P = 0.01, 95% CI = 1.23-4.87) and 2.19 (P = 0.013, 95% CI = 1.18-4.08), respectively. Genotype distribution of the TNF-α -238 variants did not yield a statistically significant difference between the two groups (P = 0.87).

CONCLUSION

TNF-α -308 G/A polymorphism seems to be associated with POAG in Turkish population. However, population-based studies with large number of subjects and long-term follow-up are needed to verify the association of TNF-α -308 G/A polymorphism with glaucoma susceptibility.

Innovative analyses support a role for DNA damage and an aberrant cell cycle in myelodysplastic syndrome pathogenesis

We used flow cytometry to analyze the cell cycle, DNA damage, and apoptosis in hematopoietic subsets in MDS marrow. Subsets were assigned using CD45, side scatter, CD34, and CD71. Cell cycle fractions were analyzed using DRAQ 5 (DNA content) and MPM-2 (mitoses). DNA damage was assessed using p-H2A.X, and apoptosis using Annexin V. Compared to controls, MDS patients demonstrated no increased mitoses in erythroid, myeloid, or CD34+ cells. Myeloid progenitors demonstrated increased G2 cells, which with no increased mitoses suggested delayed passage through G2. Myeloid progenitors demonstrated increased p-H2A.X, consistent with DNA damage causing this delay. Annexin V reactivity was equivalent in MDS and controls. Results for each parameter varied among hematopoietic compartments, demonstrating the need to analyze compartments separately. Our results suggest that peripheral cytopenias in MDS are due to delayed cell cycle passage of marrow progenitors and that this delayed passage and leukemic progression derive from excessive DNA damage.

Recurrent expression signatures of cytokines and chemokines are present and are independently prognostic in acute myelogenous leukemia and myelodysplasia

The role of circulating cytokines and chemokines (C&Ckine) in activating signal transduction in leukemic cells is incompletely defined. We hypothesized that comprehensive profiling of C&Ckine expression in leukemia would provide greater insight compared with individual analyses. We used multiplex array technology to simultaneously measure the level of 27 C&Ckines in serum from 176 acute myelogenous leukemia (AML) and 114 myelodysplastic syndrome (MDS) patients and 19 normal controls. C&Ckine levels in AML and MDS differed significantly from normal controls (5 higher, 13 lower) but were similar to each other for 24 of 27 analytes, with interleukin-8 and interleukin-13 higher in AML and vascular endothelial growth factor A higher in MDS. Levels did not correlate with age, gender, infection, or blood counts; however, 3 correlated with specific cytognetic abnormalities in AML. Individually, few cytokines had any correlation with response or survival. In newly diagnosed AML, 8 C&Ckine signatures, distinct from the normal control signature, were observed. These signatures had prognostic impact, affecting remission, primary resistance, relapse rates, and overall survival, individually (P = .003) and in multivariable analysis (P = .004). These patterns suggest specific therapeutic interventions to investigate in subsets of AML patients. In conclusion, C&Ckine expression in AML and MDS differs from normal, is similar with one another, and forms recurrent patterns of expression with prognostic relevance.

Aberrant myeloid maturation identified by flow cytometry in primary myelofibrosis

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm that may display a variable degree of cytopenia and dysplasia sometimes difficult to distinguish from myelodysplastic syndrome with myelofibrosis (MDS-MF). We reviewed flow cytometric features of bone marrow from 70 cases of PMF and compared them with those from 17 cases of MDS-MF and 20 nonneoplastic control cases. The results were correlated with JAK2(V617F) and cytogenetic findings. Granulocytes and monocytes from PMF cases exhibited multiple dysplastic features overlapping with those of MDS-MF at a comparable or higher frequency: low side scattering, aberrant CD56 expression in granulocytes and monocytes, and an abnormal CD13/CD16 maturation pattern. Unique to PMF was the small granulocyte size compared with that of MDS-MF and control cases. Although the percentage of CD56+ granulocytes and monocytes did not correlate with JAK2(V617F) or cytogenetic abnormalities, a subset analysis of 36 cases revealed that median fluorescence intensity of CD56 expression correlated positively with the presence of cytogenetic abnormalities. Our findings indicate that although there is considerable overlap between PMF and MDS-MF, the smaller granulocytes observed in PMF are a useful distinguishing feature.

Haploinsufficiency of Apc leads to ineffective hematopoiesis

Loss of a whole chromosome 5 or a deletion of the long arm of chromosome 5, -5/del(5q), is a recurring abnormality in myeloid neoplasms. The APC gene is located at chromosome band 5q23, and is deleted in more than 95% of patients with a -5/del(5q), raising the question of whether haploinsufficiency of APC contributes to the development of myeloid neoplasms with loss of 5q. We show that conditional inactivation of a single allele of Apc in mice leads to the development of severe anemia with macrocytosis and monocytosis. Further characterization of the erythroid lineage revealed that erythropoiesis is blocked at the early stages of differentiation. The long-term hematopoietic stem cell (LT-HSC) and short-term HSC (ST-HSC) populations are expanded in Apc-heterozygous mice compared with the control littermates; however, the HSCs have a reduced capacity to regenerate hematopoiesis in vivo in the absence of a single allele of Apc. Apc heterozygous myeloid progenitor cells display an increased frequency of apoptosis, and decreased in vitro colony-forming capacity, recapitulating several characteristic features of myeloid neoplasms with a -5/del(5q). Our results indicate that haploinsufficiency of Apc impairs hematopoiesis, and raise the possibility that loss of function of APC contributes to the development of myelodysplasia.

Infliximab chimeric antitumor necrosis factor-α monoclonal antibody as potential treatment for myelodysplastic syndromes

Accumulating evidence indicates tumor necrosis factor-a (TNF-a) as a key cytokine in the pathogenesis of the myelodysplastic syndromes (MDS). The identification of TNF-a as a regulator of apoptosis and the increased susceptibility of MDS cells to this cytokine provided the basis for several clinical trials of TNF inhibitors. Infliximab is an IgG1 chimeric anti-TNF-a monoclonal antibody composed of human constant and murine variable regions that bind specifically to both soluble and membrane-bound TNF-a. To date, only 2 studies have investigated the use of infliximab in patients with low-risk MDS. In both reports the drug showed a limited but significant activity and a favorable side-effect profile. In some patients, hematopoietic response was associated with decreased apoptosis as well as a decrease in abnormal metaphases by 50%. Further studies are currently underway and should provide useful information to define the more responsive subtypes of MDS, the patient characteristics, and the proper dosing regimen.

Remicade as TNF Suppressor in Patients with Myelodysplastic Syndromes

Remicade, a chimeric human-murine monoclonal antibody capable of neutralizing tumor necrosis factor alpha was given to 37 low-risk myelodysplastic syndromes (MDS) patients in two cohorts; 5 and 10 mg/kg intravenously every 4 weeks for 4 cycles. Median age was 68 years, 33 had primary MDS, 14 had refractory anemia (RA), 14 RA with ringed sideroblasts, 9 RA with excess blasts. Nine patients stopped therapy prior to completing 4 cycles, 3 from cohort 1 and 6 from cohort 2 and response was evaluated using the International Working Group criteria in 28 patients who completed the 4 cycles. Six patients showed disease progression, 14 had stable disease and 8 showed hematologic responses, 3/15 (20%) in cohort 1 and 5/13 (38%) in cohort 2. Two patients had multi-lineage responses, 2 had > 100% increase in absolute neutrophils, 1 had > 1 gm/dl increase in hemoglobin, 1 had reduction in blasts from 7% to 1%, and 2 had minor cytogenetic responses (> 50% reduction in + 8 and 20q-metaphases respectively). We conclude that Remicade may have a variety of activities in low risk MDS patients, is well tolerated with a high patient compliance, and may be considered for combination therapy in the future.

Myelodysplastic syndromes and acute myeloid leukemia in cats infected with feline leukemia virus clone33 containing a unique long terminal repeat

Feline leukemia virus (FeLV) clone33 was obtained from a domestic cat with acute myeloid leukemia (AML). The long terminal repeat (LTR) of this virus, like the LTRs present in FeLV from other cats with AML, differs from the LTRs of other known FeLV in that it has 3 tandem direct 47-bp repeats in the upstream region of the enhancer (URE). Here, we injected cats with FeLV clone33 and found 41% developed myelodysplastic syndromes (MDS) characterized by peripheral blood cytopenias and dysplastic changes in the bone marrow. Some of the cats with MDS eventually developed AML. The bone marrow of the majority of cats with FeLV clone33 induced MDS produced fewer erythroid and myeloid colonies upon being cultured with erythropoietin or granulocyte-macrophage colony-stimulating factor (GM-SCF) than bone marrow from normal control cats. Furthermore, the bone marrow of some of the cats expressed high-levels of the apoptosis-related genes TNF-alpha and survivin. Analysis of the proviral sequences obtained from 13 cats with naturally occurring MDS reveal they also bear the characteristic URE repeats seen in the LTR of FeLV clone33 and other proviruses from cats with AML. Deletions and mutations within the enhancer elements are frequently observed in naturally occurring MDS as well as AML. These results suggest that FeLV variants that bear URE repeats in their LTR strongly associate with the induction of both MDS and AML in cats.

Polymorphisms in TGFbeta and TNFalpha are associated with the myelodysplastic syndrome phenotype

CONTEXT

Myelodysplastic syndromes (MDSs) are characterized by ineffective hematopoiesis, excessive apoptosis, and the aberrant expression of a number of cytokines. The genes encoding these cytokines are significantly polymorphic. It is unknown whether these cytokine polymorphisms are associated with, and may therefore be playing a role in the pathogenesis of, MDS.

OBJECTIVE

To determine if certain polymorphisms in the tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) cytokines are overrepresented in a cohort of patients with MDSs.

DESIGN

DNA was isolated from the peripheral blood or bone marrow aspirate of 21 patients with MDS. The genotypes for 4 different polymorphisms, 2 in TNFalpha and 2 in TGFbeta1, were determined using single-specific-primer polymerase chain reaction. The allele and genotype frequencies were compared with similar populations in the National Cancer Institute SNP500 database.

RESULTS

In our MDS population, the -308A/A genotype of the TNFalpha gene and the TGFbeta1 allele +29T and genotype +29T/T, each associated with higher levels of expression, were overrepresented in our MDS population.

CONCLUSIONS

Polymorphisms associated with increased expression in the cytokines TNFalpha and TGFbeta1 are overrepresented in the MDS population suggesting that increased TNF-alpha and TGF-beta1 activity may contribute to the susceptibility and/or pathogenesis of MDS. Further studies with larger sample sizes are warranted to confirm our observation.

Apoptosis and antiapoptotic mechanisms in the progression of myelodysplastic syndrome

Myelodysplastic syndrome (MDS), previously known as preleukemia, comprises a spectrum of heterogeneous, clonal disorders of hematopoiesis. A patient's life expectancy can range from a few months to more than a decade. Recent studies provide some insight into the pathophysiology of MDS. One mechanism contributing to the constellation of hypercellular marrow and peripheral blood cytopenia is a significant increase in programmed cell death (apoptosis) in hematopoietic cells. Tumor necrosis factor (TNF)-alpha, Fas ligand, TNF-related apoptosis-inducing ligand, and other proapoptotic cytokines are upregulated in early-stage/low-risk MDS, and neutralization of these signals can improve hematopoiesis. TNF-related apoptosis inducing ligand induces apoptosis preferentially in clonal cells, which can contribute to containment of the clone. In a proportion of patients, MDS will eventually evolve to acute leukemia. This progression has been correlated with upregulation of nuclear factor kappaB; altered expression of adaptor molecules, such as Flice inhibitory protein; and enhanced activity of antiapoptotic members of the Bcl-2 and inhibitors of apoptosis protein families. Also, the ratio of TNF receptors 1 and 2 changes in favor of receptor 2. The role of the microenvironment in the pathophysiology and progression of MDS has remained controversial, although there is evidence that stroma and matrix components, and their interactions with clonal cells, play an important role. Microarray gene-expression studies are consistent with dysregulation of apoptosis, but not all data are in agreement.

Bone marrow mononuclear cells of MDS patients are characterized by in vitro proliferation and increased apoptosis independently of stromal interactions

Enhanced proliferation of MDS progenitors is abrogated by increased apoptosis of their progeny in vivo. We investigated whether bone marrow mononuclear cells (BMMNC) of MDS patients also showed enhanced proliferation and apoptosis in vitro in comparison with acute myeloid leukemia (AML) and normal BM (NBM). NBM showed a decrease in the number of clusters in time due to apoptosis of clusters and due to development of clusters into colonies with low apoptotic level. In MDS patients, about two-fold more clusters have developed at day 4, and in contrast with NBM, the total number of clusters at day 7 remained high in spite of an increasing percentage of apoptotic clusters (from 52 to 76%) in combination with more colony formation. The number of clusters and colonies showed a sharp decrease at day 10 because of persistently high apoptosis at cluster level and increasing apoptosis in colonies. BMMNC of AML patients showed a decreased proliferation with enhanced apoptosis at cluster level in contrast to a relatively low apoptotic levels in the colony-forming cells. This data show that increased proliferation is abrogated by enhanced apoptosis in MDS, whereas AML showed decreased proliferation with a low level of apoptosis in colony-forming cells. These growth profiles of BMMNC are independent of stromal influences and may represent intrinsic features of the MDS progenitors and accessory cell interactions.