Haematological response of patients with myelodysplastic syndrome to antithymocyte globulin is associated with a loss of lymphocyte-mediated inhibition of CFU-GM and alterations in T-cell receptor Vbeta profiles

Bone Marrow Immune Microenvironment in Myelodysplastic Syndromes

The BM, the major hematopoietic organ in humans, consists of a pleiomorphic environment of cellular, extracellular, and bioactive compounds with continuous and complex interactions between them, leading to the formation of mature blood cells found in the peripheral circulation. Systemic and local inflammation in the BM elicit stress hematopoiesis and drive hematopoietic stem cells (HSCs) out of their quiescent state, as part of a protective pathophysiologic process. However, sustained chronic inflammation impairs HSC function, favors mutagenesis, and predisposes the development of hematologic malignancies, such as myelodysplastic syndromes (MDS). Apart from intrinsic cellular mechanisms, various extrinsic factors of the BM immune microenvironment (IME) emerge as potential determinants of disease initiation and evolution. In MDS, the IME is reprogrammed, initially to prevent the development, but ultimately to support and provide a survival advantage to the dysplastic clone. Specific cellular elements, such as myeloid-derived suppressor cells (MDSCs) are recruited to support and enhance clonal expansion. The immune-mediated inhibition of normal hematopoiesis contributes to peripheral cytopenias of MDS patients, while immunosuppression in late-stage MDS enables immune evasion and disease progression towards acute myeloid leukemia (AML). In this review, we aim to elucidate the role of the mediators of immune response in the initial pathogenesis of MDS and the evolution of the disease.

Hospital-Based Case-Control Study of MDS Subtypes and Benzene Exposure in Shanghai

OBJECTIVE

Due to the sparse data on benzene exposure and myelodysplastic syndrome (MDS) subtypes, we studied this relationship in patients from 29 hospitals in Shanghai, China.

METHODS

We recruited 604 cases of MDS and 1193 controls matched on age, sex, and admission date. We interviewed subjects for information on workplace and lifestyle exposures, and developed semi-quantitative exposure estimates.

RESULTS

Benzene exposure showed a direct exposure-response pattern with refractory cytopenia with multilineage dysplasia, a less certain association with refractory cytopenia with unilineage dysplasia, and no association with other MDS subtypes. A different pattern was observed with farm residence and smoking, which was primarily related to refractory anemias.

CONCLUSIONS

This research demonstrates the importance of MDS subtype specification for more robust etiologic insights. Our data suggests that subtypes with non-erythroid dysplasia are associated with benzene exposure.

Comparison of T lymphocyte subsets in aplastic anemia and hypoplastic myelodysplastic syndromes

AIMS

This study aims to compare the proportion of peripheral blood T lymphocyte subsets and related blood cell and bone marrow cytology indexes between patients with aplastic anemia (AA) and hypoplastic myelodysplastic syndrome (hypo-MDS), and investigate the clinical identification significance.

MATERIALS AND METHODS

A total of 41 patients with AA and 46 patients with hypo-MDS were collected, and the proportions of peripheral blood T lymphocyte subsets, CD3^-CD16/CD56⁺NK cells, CD3⁺CD57⁺T-LGL cells and CD19⁺B lymphocytes were detected by flow cytometry.

KEY FINDINGS

The CD4⁺/CD8⁺ ratio decreased in the AA and hypo-MDS groups, and the difference was statistically significant when compared with that in the control group (P<0.05). However, there was no significant difference between AA and hypo-MDS groups (P>0.05). The proportions of CD3^-CD16/CD56⁺NK cells and CD3⁺CD57⁺T-LGL cells in the hypo-MDS group were distinctly higher than those in the AA group (P<0.05). However, the proportion of CD19⁺B lymphocyte was obviously lower than that in the AA group (P<0.05). Furthermore, the proportions of reticulocytes, bone marrow progenitor cells and immature red blood cells in the hypo-MDS group were significantly more than those in the AA group (P<0.05), and the proportion of mature lymphocytes in the hypo-MDS group was distinctly lower than that in the AA group (P<0.05).

SIGNIFICANCE

Changes of T lymphocyte subsets and the proportions of large granular lymphocytes and B lymphocytes can be utilized as indexes in the differential diagnosis between AA and hypo-MDS.

Polymorphisms of Interlukin-1β rs16944 confer susceptibility to myelodysplastic syndromes

Genetic factors have been shown to be associated with Myelodysplastic syndromes (MDS) susceptibility. In recent years, the role of inflammation in the promotion of tumor growth is supported by a broad range of experimental and clinical evidence. But the relationship between polymorphisms in NOD-like receptor protein 3 (NLRP3) inflammasome and MDS is rarely reported. Thus, we conducted a case-control study, and genotyped five single nucleotide polymorphisms (SNPs) (NLRP3, IL-1β, IL-18, CARD8, and NF-κB) in MDS patients and healthy controls. The association of different genotypes with patient characteristics was analyzed. Comparing MDS patients with controls, GG genotype of IL-1β (rs16944) was observed to be associated with a significantly increased risk of MDS 78/166 (48.8%) vs 26/96 (27.0%), OR=2.1, CI (1.0-4.4). No significant association was identified regarding the rest of investigated polymorphisms and MDS susceptibility. Complex karyotypes were more frequent in patients with GG genotype of IL-1β (rs16944). Patients with IL-1β polymorphisms (rs16944) GG and GA had lower hemoglobin than those without. Patients with IL-1β polymorphisms (rs16944) GG had higher IPSS scores than those without IL-1β polymorphisms. In conclusion, our present data shows that the IL-1β polymorphisms (rs16944) GG were frequently occurred in MDS. IL-1β (rs16944) GG genotype might serve as a novel biomarker and potential targets for MDS.

The immune landscape of myelodysplastic syndromes

Even though the pathogenesis of myelodysplastic syndromes (MDS) is dominated by specific molecular defects involving hematopoietic precursors, also immune mechanisms seem to play a fundamental functional role. In this review we will first describe the clinical and laboratory autoimmune manifestations often detectable in MDS patients. We will then focus on studies addressing the possible influence of different immune cell subpopulations on the disease onset and evolution. We will finally consider therapeutic approaches based on immunomodulation, ranging from immunosuppressants to vaccination and transplantation strategies.

Immune Mechanisms in Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is a spectrum of diseases, characterized by debilitating cytopenias and a propensity of developing acute myeloid leukemia. Comprehensive sequencing efforts have revealed a range of mutations characteristic, but not specific, of MDS. Epidemiologically, autoimmune diseases are common in patients with MDS, fueling hypotheses of common etiological mechanisms. Both innate and adaptive immune pathways are overly active in the hematopoietic niche of MDS. Although supportive care, growth factors, and hypomethylating agents are the mainstay of MDS treatment, some patients—especially younger low-risk patients with HLA-DR15 tissue type—demonstrate impressive response rates after immunosuppressive therapy. This is in contrast to higher-risk MDS patients, where several immune activating treatments, such as immune checkpoint inhibitors, are in the pipeline. Thus, the dual role of immune mechanisms in MDS is challenging, and rigorous translational studies are needed to establish the value of immune manipulation as a treatment of MDS.

Effects of arsenic disulfide on proliferation, cytokine production, and frequencies of CD4(+), CD8(+), and regulatory T cells in mitogen-activated human peripheral blood mononuclear cells

Influence of arsenic disulfide (As2S2) on human immune cells has little been investigated. Effects of As2S2 on proliferation, cytokine production, and frequencies of CD4(+) T, CD8(+) T and CD4(+)CD25(+)Foxp3(+) regulatory T cells in mitogen-activated human peripheral blood mononuclear cells were examined. Anti-proliferative effects of As2S2 on peripheral blood mononuclear cells activated by T-cell mitogen were assessed by a colorimetric assay. Cytokine concentrations in the culture medium were measured with beads-array procedures followed by flow cytometry. CD4(+) T cells, CD8(+) T cells and CD4(+)CD25(+)Foxp3(+) regulatory T cells were stained with fluorescence-labeled specific antibodies followed by flow cytometry analysis. As2S2 at 1-10μM significantly suppressed mitogen-activated proliferation of peripheral blood mononuclear cells (p<0.05). As2S2 at 10μM inhibited production of IL-6, -10, -17A, tumor necrosis factor-α, and interferon-γ from the activated peripheral blood mononuclear cells, though the effects were not statistically significant. As2S2 at 10μM significantly suppressed the frequencies of CD4(+) T and CD8(+) T cells (p<0.05), whereas significantly enhanced the frequency of CD4(+)CD25(+)Foxp3(+) regulatory T cells (p<0.05). The data suggest that As2S2 attenuates T cell-mediated immunity by not only suppressing the proliferation of T cells and cytokine release but also increasing the frequency of regulatory T cells. T cell-mediated autoimmunity contributes to bone marrow failure in myelodysplastic syndrome (MDS), and thus the above As2S2 effects are beneficial for the treatment of MDS patients.

T-cell receptor Vβ skewing frequently occurs in refractory cytopenia of childhood and is associated with an expansion of effector cytotoxic T cells: a prospective study by EWOG-MDS

Immunosuppressive therapy (IST), consisting of antithymocyte globulin and cyclosporine A, is effective in refractory cytopenia of childhood (RCC), suggesting that, similar to low-grade myelodysplastic syndromes in adult patients, T lymphocytes are involved in suppressing hematopoiesis in a subset of RCC patients. However, the potential role of a T-cell-mediated pathophysiology in RCC remains poorly explored. In a cohort of 92 RCC patients, we prospectively assessed the frequency of T-cell receptor (TCR) β-chain variable (Vβ) domain skewing in bone marrow and peripheral blood by heteroduplex PCR, and analyzed T-cell subsets in peripheral blood by flow cytometry. TCRVβ skewing was present in 40% of RCC patients. TCRVβ skewing did not correlate with bone marrow cellularity, karyotype, transfusion history, HLA-DR15 or the presence of a PNH clone. In 28 patients treated with IST, TCRVβ skewing was not clearly related with treatment response. However, TCRVβ skewing did correlate with a disturbed CD4(+)/CD8(+) T-cell ratio, a reduction in naive CD8(+) T cells, an expansion of effector CD8(+) T cells and an increase in activated CD8(+) T cells (defined as HLA-DR(+), CD57(+) or CD56(+)). These data suggest that T lymphocytes contribute to RCC pathogenesis in a proportion of patients, and provide a rationale for treatment with IST in selected patients with RCC.

A phase II multicenter rabbit anti-thymocyte globulin trial in patients with myelodysplastic syndromes identifying a novel model for response prediction

Immune dysregulation is a mechanism contributing to ineffective hematopoiesis in a subset of myelodysplastic syndrome patients. We report the first US multicenter non-randomized, phase II trial examining the efficacy of rabbit(r)-anti-thymocyte globulin using 2.5 mg/kg/day administered daily for 4 doses. The primary end point was hematologic response; secondary end points included duration of response, time to response, time to progression, and tolerance. Nine (33%;95% confidence interval=17%-54%) of the 27 patients treated experienced durable hematologic improvement in an intent-to-treat analysis with a median time to response and median response duration of 75 and 245 days, respectively. While younger age is the most significant factor favoring equine(e)-anti-thymocyte globulin response, treatment outcome on this study was independent of age (P=0.499). A shorter duration between diagnosis and treatment showed a positive trend (P=0.18), but International Prognostic Scoring System score (P=0.150), karyotype (P=0.319), and age-adjusted bone marrow cellularity (P=0.369) were not associated with response classification. Since activated T-lymphocytes are the primary cellular target of anti-thymocyte globulin, a T-cell expression profiling was conducted in a cohort of 38 patients consisting of rabbit and equine-antithymocyte globulin-treated patients. A model containing disease duration, CD8 terminal memory T cells and T-cell proliferation-associated-antigen expression predicted response with the greatest accuracy using a leave-one-out cross validation approach. This profile categorized patients independent of other covariates, including treatment type and age using a leave-one-out-cross-validation approach (75.7%). Therefore, rabbit-anti-thymocyte globulin has hematologic remitting activity in myelodysplastic syndrome and a T-cell activation profile has potential utility classifying those who are more likely to respond (NCT00466843 clinicaltrials.gov).

Proteins related to the spindle and checkpoint mitotic emphasize the different pathogenesis of hypoplastic MDS

Some studies show that alterations in expression of proteins related to mitotic spindle (AURORAS KINASE A and B) and mitotic checkpoint (CDC20 and MAD2L1) are involved in chromosomal instability and tumor progression in various solid and hematologic malignancies. This study aimed to evaluate these genes in MDS patients. The cytogenetics analysis was carried out by G-banding, AURKA and AURKB amplification was performed using FISH, and AURKA, AURKB, CDC20 and MAD2L1 gene expression was performed by qRT-PCR in 61 samples of bone marrow from MDS patients. AURKA gene amplification was observed in 10% of the cases, which also showed higher expression levels than the control group (p=0.038). Patients with normo/hypercellular BM presented significantly higher expression levels than hypocellular BM patients, but normo and hypercellular BM groups did not differ. After logistic regression analysis, our results showed that HIGH expression levels were associated with increased risk of developing normo/hypercellular MDS. It also indicated that age is associated with AURKA, CDC20 and MAD2L1 HIGH expression levels. The distinct expression of hypocellular patients emphasizes the prognostic importance of cellularity to MDS. The amplification/high expression of AURKA suggests that the increased expression of this gene may be related to the pathogenesis of disease.

Comparison of horse and rabbit antithymocyte globulin in immunosuppressive therapy for refractory cytopenia of childhood

Refractory cytopenia of childhood is the most common subtype of myelodysplastic syndrome in children. In this study, we compared the outcome of immunosuppressive therapy using horse antithymocyte globulin (n=46) with that using rabbit antithymocyte globulin (n=49) in 95 patients with refractory cytopenia of childhood and hypocellular bone marrow. The response rate at 6 months was 74% for horse antithymocyte globulin and 53% for rabbit antithymocyte globulin (P=0.04). The inferior response in the rabbit antithymocyte globulin group resulted in lower 4-year transplantation-free (69% versus 46%; P=0.003) and failure-free (58% versus 48%; P=0.04) survival rates in this group compared with those in the horse antithymocyte globulin group. However, because of successful second-line hematopoietic stem cell transplantation, overall survival was comparable between groups (91% versus 85%; P=ns). The cumulative incidence of relapse (15% versus 9%; P=ns) and clonal evolution (12% versus 4%; P=ns) at 4 years was comparable between groups. Our results suggest that the outcome of immunosuppressive therapy with rabbit antithymocyte globulin is inferior to that of horse antithymocyte globulin. Although immunosuppressive therapy is an effective therapy in selected patients with refractory cytopenia of childhood, the long-term risk of relapse or clonal evolution remains. (ClinicalTrial.gov identifiers: NCT00662090).

Myelodysplastic syndromes: toward a risk-adapted treatment approach

Several classification and scoring systems have been developed in myelodysplastic syndromes (MDS to predict the risk of progression to acute myeloid leukemia and survival. These prognostication models have been also used to inform therapeutic decision-making in a risk-adapted fashion. Patient-related factors such as age, comorbidities, and functional status have to be considered as well. Here we review a risk-guided therapeutic approach for the management of MDS patients. It is anticipated that the improved understanding of the complex pathogenesis of MDS and the recent discovery of important molecular lesions will be translated into novel therapeutic approaches. Additionally, some prognostic aberrations are expected to be incorporated into the prognostic tools with the goal of improving their prognostic precision and therefore allow for a more informed therapeutic decision-making based on the individual's risk profile.

BCR CDR3 length distributions differ between blood and spleen and between old and young patients, and TCR distributions can be used to detect myelodysplastic syndrome

Complementarity-determining region 3 (CDR3) is the most hyper-variable region in B cell receptor (BCR) and T cell receptor (TCR) genes, and the most critical structure in antigen recognition and thereby in determining the fates of developing and responding lymphocytes. There are millions of different TCR Vβ chain or BCR heavy chain CDR3 sequences in human blood. Even now, when high-throughput sequencing becomes widely used, CDR3 length distributions (also called spectratypes) are still a much quicker and cheaper method of assessing repertoire diversity. However, distribution complexity and the large amount of information per sample (e.g. 32 distributions of the TCRα chain, and 24 of TCRβ) calls for the use of machine learning tools for full exploration. We have examined the ability of supervised machine learning, which uses computational models to find hidden patterns in predefined biological groups, to analyze CDR3 length distributions from various sources, and distinguish between experimental groups. We found that (a) splenic BCR CDR3 length distributions are characterized by low standard deviations and few local maxima, compared to peripheral blood distributions; (b) healthy elderly people's BCR CDR3 length distributions can be distinguished from those of the young; and (c) a machine learning model based on TCR CDR3 distribution features can detect myelodysplastic syndrome with approximately 93% accuracy. Overall, we demonstrate that using supervised machine learning methods can contribute to our understanding of lymphocyte repertoire diversity.

Immunomodulatory treatment of myelodysplastic syndromes: antithymocyte globulin, cyclosporine, and alemtuzumab

It is now well accepted that a subgroup of patients with myelodysplastic syndromes (MDS) can recover from pancytopenia following immunosuppressive treatment (IST). For many years immunosuppression with antilymphocyte antibodies has been a standard treatment approach for patients with severe aplastic anemia (SAA). The initial concept of using immunosuppression to treat pancytopenic patients with MDS was based on the premise that MDS might share with SAA an autoimmune basis for the bone marrow failure common to both conditions. The idea was supported by reports of favorable outcomes in occasional cases of MDS treated with antithymocyte globulin (ATG). Today, various forms of IST have been successfully used to restore hematopoiesis in MDS in many centers worldwide. In this review we outline the rationale for use of IST in MDS, and describe studies which help to define the patients with MDS likely to respond to IST. We summarize 18 published clinical trials using IST for MDS and discuss how these studies have helped to define the MDS subgroups likely to respond to treatment, the nature and durability of the response, the impact of IST on long-term outcome, and the best treatment approach.

Th22 cells as well as Th17 cells expand differentially in patients with early-stage and late-stage myelodysplastic syndrome

BACKGROUND

Immunological mechanisms are increasingly recognized in the progression of myelodysplastic syndrome (MDS). Early-stage MDS (E-MDS) is characterized by autoimmune-mediated myelosuppression whereas late-stage MDS (L-MDS) involves immune evasion, giving dysplastic cells growth potential to progress into acute myeloid leukemia. T-helper (Th) 22 is involved in the pathogenesis of inflammatory autoimmunity and tumorigenesis. The roles of Th22 cells in the pathophysiology of E-MDS and L-MDS remain unsettled.

DESIGN AND METHODS

We studied 37 MDS patients (E-MDS, n = 17; L-MDS, n = 20) and 20 healthy controls to characterize their peripheral blood (PB), as well as 25 MDS patients and 10 healthy controls to characterize their bone marrow(BM). The expression of Interleukin-22 (IL-22), IL-17 or interferon gamma (IFN-γ) was examined in E-MDS, L-MDS patients and controls by flow cytometry. The mRNA expression levels of RAR-related orphan receptor C (RORC), IL-6, tumor necrosis factor alpha (TNF-α) and IL-23 in peripheral blood mononuclear cells (PBMCs) were determined by real-time quantitative polymerase chain reaction. The levels of IL-22 and IL-17 both in PB and BM plasma were examined by enzyme-linked immunosorbent assay.

RESULTS

In E-MDS, peripheral Th17 cells were significantly elevated and correlated with peripheral Th22 cells compared with healthy controls and L-MDS. Significantly higher levels of peripheral Th22 expansion, mRNA expression of IL-6, TNF-α and lower level of RORC mRNA expression were observed in L-MDS compared with E-MDS. No statistical difference was found in IL-23 mRNA expression or plasma IL-22, IL-17 levels among E-MDS, L-MDS and controls.

CONCLUSIONS

Our data demonstrated that L-MDS cohort had increased frequencies of peripheral Th22 cells and higher mRNA expression levels of IL-6 and TNF-α, indicating that Th22 cells along with Th17 cells or not are involved in the dynamic immune responses of MDS.

The role of T-cells in the pathogenesis of myelodysplastic syndromes: passengers and drivers

Although a burden of clinical and experimental data suggest the involvement of T-lymphocytes in the pathogenesis of myelodysplastic syndromes (MDS), the actual weight exerted by T-cells in this scenario is yet to be conclusively dissected. This brief review will try to further address this point, by running through the most relevant studies exploring the T-cell repertoire of MDS patients as well as the potential role of specific T-cell subsets such as regulatory T-cells and Th17 T-cells.

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.

Immune dysregulation in myelodysplastic syndrome

Myelodysplastic syndrome (MDS) represents one of the most challenging health-related problems in the elderly. Characterized by dysplastic morphology in the bone marrow in association with ineffective hematopoiesis, pathophysiological causes of this disease are diverse including genetic abnormalities within myeloid progenitors, altered epigenetics, and changes in the bone marrow microenvironment. The concept that T-cell mediated autoimmunity contributes to bone marrow failure has been widely accepted due to hematologic improvement after immunosuppressive therapy (IST) in a subset of patients. Currently, IST for MDS primarily involves anti-thymocyte globulin (ATG)-based regimens in which responsiveness is strongly associated with younger (under 60 years) age at disease onset. In such cases, progressive cytopenia may occur as a consequence of expanded self-reactive CD8⁺ cytotoxic T lymphocytes (CTLs) that suppress hematopoietic progenitors. Although most hematologists agree that IST can offer durable hematologic remission in younger patients with MDS, an international clinical study and a better understanding of the molecular mechanisms contributing to the expansion of self-reactive CTLs is crucial. In this review, data accumulated in the US, Europe, and Asia will be summarized to provide insight and direction for a multi-center international trial.

Expansion of effector memory regulatory T cells represents a novel prognostic factor in lower risk myelodysplastic syndrome

Myelodysplastic syndromes are premalignant diseases characterized by cytopenias, myeloid dysplasia, immune dysregulation with association to autoimmunity, and variable risk for acute myeloid leukemia transformation. Studies of FOXP3(+) regulatory T cells (Tregs) indicate that the number and/or activation state may influence cancer progression in these patients. Focusing on patients with a lower risk for leukemia transformation, 18 (34.6%) of 52 patients studied displayed an altered Treg compartment compared with age-matched controls. Delineation of unique Treg subsets revealed that an increase in the absolute number of CD4(+)FOXP3(+)CD25(+)CD127(low)CD45RA(-)CD27(-) Tregs (effector memory Tregs [Treg(EM)]) was significantly associated with anemia (p = 0.046), reduced hemoglobin (p = 0.038), and blast counts ≥5% (p = 0.006). In healthy donors, this Treg(EM) population constitutes only 2% of all Tregs (one to six Tregs per microliter) in peripheral blood but, when isolated, exhibit greater suppressive activity in vitro. With a median follow-up of 3.1 y (range 2.7-4.9 y) from sample acquisition, increased numbers of Treg(EM) cells proved to have independent prognostic importance in survival estimates, suggesting that enumeration of this Treg subset may be a more reliable indicator of immunological escape than FOXP3(+) T cells as a whole. Based on multivariate analyses, Treg(EM) impacted survival independently from myeloblast characteristics, cytopenias, karyotype, and comorbidities. Based on these findings, Treg(EM) cell expansion may be synonymous with human Treg activation and indicate microenvironmental changes conducive to transformation in myelodysplastic syndromes.

Apoptotic cells and clonally expanded cytotoxic T cells in bone marrow trephines of patients with myelodysplastic syndrome

AIMS

There is increasing evidence that autoimmunity is involved in the pathogenesis of myelodysplastic syndromes (MDS). We examined the number of apoptotic cells, and analysed the T cells and the T cell receptor gene rearrangements in bone marrow trephines of patients with low-grade MDS [refractory anaemia (RA), refractory anaemia with ringed sideroblasts (RAS) and refractory cytopenia with multilineage dysplasia (RCMD)] to investigate the correlation between T cells and apoptosis.

METHODS AND RESULTS

Bone marrow trephines from 30 patients with RA, seven patients with RCMD, four patients with RAS and 11 normal bone marrow donors were stained for CD3 and for apoptotic cells using immunohistochemistry and terminal deoxynucleotidyl transferase 2'-deoxyuridine, 5'-triphosphate (dUTP) nick end labelling (TUNEL) technique, respectively. The positive cells were quantified by computer-assisted image analysis. In addition, CD 8 and T cell-restricted intracellular antigen-1 (TIA-1)-positive cells were analysed by single staining and evaluated semiquantitatively by light microscopy. Junctional diversity of the T cell receptor (TCR) α-, β- and γ-chains were analysed in 24 cases of RA and RCMD by reverse transcription-polymerase chain reaction (RT-PCR). In all cases of RA, RCMD and RAS an increase of apoptotic cells was accompanied by an increase of T cells, when compared to normal donors (P < 0.001). Expression of TIA-1 was found in 33 of 41 patients with low-grade MDS. In contrast, normal controls showed either no or only very weak expression. Furthermore, 14 of 24 cases with low-grade MDS showed clonal TCR gene rearrangement.

CONCLUSION

These findings provide evidence that increased apoptosis in low-grade MDS correlates with increased numbers of cytotoxic T cells. A considerable proportion of the MDS cases showed clonal TCR rearrangement suggesting an antigen-driven selection of the T cells. We therefore speculate that cases of MDS can be accompanied by a presumably autoreactive T cell-mediated apoptosis induction in bone marrow cells.

Update on the science of myelodysplastic syndromes

Scientific research is only just beginning to shed light on the pathobiology underlying the various subtypes of myelodysplastic syndromes (MDS), a heterogeneous group of clonal stem cell disorders characterized by cytopenias that can progress to acute myeloid leukemia. Increased understanding of the disease and prognostic implications of specific clinical features has aided in the development of prescribing guidelines and new treatments for MDS. Because oncology nurses have frequent interactions with patients during diagnostic and therapeutic evaluations, an understanding of the science behind disease classification, prognostic scoring, and the goals of treatment for low- and high-risk disease is important to answer questions regarding diagnostic results, treatment outcomes, and adverse event monitoring.

Depletion of cytotoxic T-cells does not protect NUP98-HOXD13 mice from myelodysplastic syndrome but reveals a modest tumor immunosurveillance effect

Myelodysplastic syndrome (MDS) and aplastic anemia (AA) patients both present with symptoms of bone marrow failure. In many AA patients, these features are thought to result from an oligoclonal expansion of cytotoxic T-cells that destroy haematopoietic stem or progenitor cells. This notion is supported by the observation that AA patients respond to immunosuppressive therapy. A fraction of MDS patients also respond well to immunosuppressive therapy suggesting a similar role for cytotoxic T-cells in the etiology of MDS, however the role of cytotoxic T-cells in MDS remains unclear. Mice that express a NUP98-HOXD13 (NHD13) transgene develop a MDS that closely mimics the human condition in terms of dysplasia, ineffective hematopoiesis, and transformation to acute myeloid leukemia (AML). We followed a cohort of NHD13 mice lacking the Rag1 protein (NHD13/Rag1KO) to determine if the absence of lymphocytes might 1) delay the onset and/or diminish the severity of the MDS, or 2) effect malignant transformation and survival of the NHD13 mice. No difference was seen in the onset or severity of MDS between the NHD13 and NHD13/Rag1KO mice. However, NHD13/Rag1KO mice had decreased survival and showed a trend toward increased incidence of transformation to AML compared to the NHD13 mice, suggesting protection from AML transformation by a modest immuno-surveillance effect. In the absence of functional Tcrb signaling in the NHD13/Rag1KO T-cell tumors, Pak7 was identified as a potential Tcrb surrogate survival signal.

Are T-cell dysfunctions the other side of the moon in the pathogenesis of myelodysplastic syndromes?

Even though the pathogenesis of myelodysplastic syndromes (MDS) is dominated by an inefficient maturation of haematopoietic precursors, also immune mechanisms seem to play a crucial functional role. In this review, we will first describe the clinical and laboratory autoimmune manifestations often detectable in MDS patients. We will then focus on studies addressing the mechanisms of T-cell activation and their implications in the disease history. The potential impact of specific cell subsets, such as regulatory T-cells, Th17 cells and natural killer cells, will be also described. We will finally focus on potential therapeutic approaches based on immunomodulation, ranging from more classical immunosuppressive drugs to vaccination and transplantation strategies.

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.

Myelodysplastic syndromes: the role of the immune system in pathogenesis

The myelodysplastic syndromes (MDS) represent a complex spectrum of clonal hematopoietic stem cell disorders manifested by cytopenias, risk of infection, and variable risk of progression to acute myelogenous leukemia. Several theories of MDS pathogenesis exist, with contributions of genetic, epigenetic, apoptotic, differentiation, and cytokine milieu abnormalities. Immune dysregulation has also been implicated in MDS pathogenesis. In some forms of MDS it is evident that immune dysregulation may be a primary pathophysiologic abnormality, while in others the abnormal immune function may represent only a small part of the pathologic puzzle. We review the current literature regarding natural killer (NK) cell, T cell, and myeloid derived suppressor cell abnormalities in the spectrum of MDS.

Immunosuppressive Therapy for Patients With Myelodysplastic Syndrome: A Prospective Randomized Multicenter Phase III Trial Comparing Antithymocyte Globulin Plus Cyclosporine With Best Supportive Care—SAKK 33/99

Purpose

Immunosuppressive treatment is reported to improve cytopenia in some patients with myelodysplastic syndrome (MDS). Combined antithymocyte globulin (ATG) and cyclosporine (CSA) is most effective in patients with immune-mediated marrow failure.

Patients and Methods

This trial was designed to assess the impact of immunosuppression on hematopoiesis, transfusion requirements, transformation, and survival in patients with MDS randomly assigned to 15 mg/kg of horse ATG for 5 days and oral CSA for 180 days (ATG+CSA) or best supportive care (BSC), stratified by treatment center and International Prognostic Scoring System (IPSS) risk score. Primary end point was best hematologic response at 6 months. Eligible patients had an Eastern Cooperative Oncology Group performance status of ≤ 2 and transfusion dependency of less than 2 years in duration.

Results

Between 2000 and 2006, 45 patients received ATG+CSA (median age, 62 years; range, 23 to 75 years; 56% men) and 43 patients received BSC (median age, 65 years; range, 24 to 76 years; 81% men). IPSS score was low, intermediate-1, intermediate-2, high, and not evaluable in eight, 24, seven, one, and five patients on ATG+CSA, respectively, and eight, 25, five, zero, and five patients on BSC, respectively. Refractory anemia, refractory anemia with ringed sideroblasts, refractory anemia with excess of blasts (RAEB) -I, RAEB-II, and hypoplastic disease were present in 21, six, nine, zero, and nine patients on ATG+CSA, respectively, and 18, eight, 11, two, and four patients on BSC, respectively. By month 6, 13 of 45 patients on ATG+CSA had a hematologic response compared with four of 43 patients on BSC (P = .0156). Two-year transformation-free survival (TFS) rates were 46% (95% CI, 28% to 62%) and 55% (95% CI, 34% to 70%) for ATG+CSA and BSC patients, respectively (P = .730), whereas overall survival (OS) estimates were 49% (95% CI, 31% to 66%) and 63% (95% CI, 42% to 78%), respectively (P = .828).

Conclusion

This open-label randomized phase III trial demonstrates that ATG+CSA treatment seems to be associated with hematologic response in a subset of patients without apparent impact on TFS and OS.

Immunosuppressive therapy for myelodysplastic syndromes: refining the indications

Myelodysplastic syndromes (MDS) are often associated with autoimmune processes that contribute to the cytopenias that characterize this disease group. Ten years ago, several investigators described improvement in the cytopenia of MDS following immunosuppressive treatments (IST) with antithymocyte globulin or cyclosporine. These findings have since been widely confirmed. The consensus is that about 30% of unselected transfusion-dependent patients with MDS given IST have sustained hematologic responses and can regain transfusion independence. Over the past decade, prognostic features have been defined that accurately identify the subset of patients most likely to benefit from IST. With increasing knowledge about the pathophysiology of myelosuppression in MDS, we are beginning to define the immunosuppressive agents and schedules with the greatest chance of causing hematologic improvement. Significantly, long-term follow-up indicates that IST responders have a better progression-free survival than comparable patients with MDS who do not receive IST.

Experimental and clinical characteristics in myelodysplastic syndrome patients with or without HLA-DR15 allele

We studied the effects of the presence of the HLA-DR15 allele on the experimental and clinical features of myelodysplastic syndrome (MDS) by assessing the clinical data of 136 patients with MDS. We observed that the frequency of HLA-DR15 expression in MDS patients (38.7%) was significantly higher than that in the healthy controls (p < 0.01). We noted the following observations with regard to disease progression: None of the 46 HLA-DR15 positive patients with international prognostic scoring system (IPSS) scores <or=1 developed acute myeloid leukaemia (AML) during the follow-up period, while six of the 63 DR15-negative patients with the same IPSS score developed AML within a shorter follow-up period (p = 0.039). Furthermore, the incidence of poor chromosomal abnormalities, the percentage of patients with IPSS scores >or=1.5 and the presence of >or=5% blasts in the bone marrow in the DR15-positive patients were lower than the corresponding findings in the DR15-negative patients. In addition, we also recorded the following observations with regard to bone marrow (BM) failure: The bicytopenia/pancytopenia ratio in the DR15-positive patients was higher than that in the DR15-negative patients (92.4 vs. 78.3%; p = 0.029). The peripheral-neutrophil count and the platelet count in the DR15-positive patients were lower than those in the DR15-negative patients (p = 0.028 and p = 0.011, respectively). Moreover, hypocellularity was more easily detectable in the DR15-positive patients (26.4 vs. 16.9%). In addition, the BM CD4+ lymphocyte count and the CD4/CD8 ratio in the DR15-positive patients were higher than the corresponding values in the DR15-negative patients (p < 0.05 for both). However, there were no significant differences between the polarization of T-helper (T(h)) and T-cytotoxic (T(c)) cells and the cytokine levels in these two patient groups. We concluded that the presence of the HLA-DR15 allele is indicative of a genetic susceptibility to MDS and, the presence of the HLA-DR15 allele showed less association with disease progression and greater association with BM failure.

Immunosuppression for myelodysplastic syndrome: how bench to bedside to bench research led to success

Laboratory evidence and clinical evidence suggest that some patients with myelodysplastic syndrome (MDS) have immunologically mediated disease. This article describes the laboratory evidence supporting a role for the immune system in the marrow failure of MDS and clinical trials using IST in these patients.

Anti-thymocyte globulin plus etanercept as therapy for myelodysplastic syndromes (MDS): a phase II study

Immunosuppressive therapies have proven valuable in treating patients with myelodysplastic syndromes (MDS). We evaluated the combination of equine anti-thymocyte globulin (ATGAM) and the soluble tumour necrosis factor receptor, etanercept (Enbrel), in a phase II trial. Twenty-five patients with MDS [4-refractory anaemia (RA), 2-RA with ring sideroblasts, 15-refractory cytopenia with multilineage dysplasia (RCMD), 3-RCMD and ring sideroblasts, 1-RA with excess blasts type 1] in International Prognostic Staging System risk groups low (n = 11) or intermediate-1 (n = 14) were enrolled. All patients were platelet or red cell transfusion-dependent. Nineteen patients completed therapy with ATG at 40 mg/kg per day for four consecutive days, followed by etanercept, 25 mg subcutaneous twice a week for 2 weeks, every month for 4 months. Thirteen patients had haematological improvement (HI)-erythroid, 2 HI-neutrophil, and 6 HI-platelet. One patient with a co-existing diagnosis of multiple sclerosis and rheumatoid arthritis had a complete remission. The overall response by intent to treat analysis among the 25 patients was 56% (95% confidence interval 35-56%). Four patients did not complete their first course of therapy and one patient did not survive to the 8-week post-treatment assessment. Among patients who completed treatment and survived to the 8-week assessment, 70% had at least haematological responses lasting for at least 5 to more than 36 months. Thus, combination therapy with ATG and etanercept was active and safe in patients with MDS.

Abnormalities of the alphabeta T-cell receptor repertoire in advanced myelodysplastic syndrome

OBJECTIVE

Analysis of the alphabeta T-cell receptor (TCR) repertoire in patients with myelodysplastic syndrome (MDS) using the technique of TCR beta-chain spectratyping has provided valuable insight into the pathophysiology of cytopenias in a subset of patients with this heterogeneous disorder. TCR beta-chain spectratypes are complex data sets, however, and statistical tools for their comprehensive analysis are limited. The objective of the present work was to develop a method to enable quantitative evaluation and global comparison of spectratype data from different individuals and to study the prevalence of TCR beta repertoire abnormalities in MDS patients.

MATERIALS AND METHODS

We developed a robust statistical method based on k-means clustering analysis, and applied this method to analysis of the alphabeta TCR repertoires in 50 MDS patients and 23 age-matched healthy controls.

RESULTS

Cluster analysis identified a subset of 11 MDS patients with profoundly abnormal alphabeta TCR repertoires. This group of patients was characterized by advanced disease by International Prognostic Scoring System and World Health Organization criteria, increased expression of the Wilms' tumor-1 oncogene, increased bone marrow myeloblast count, and older age.

CONCLUSIONS

We have developed a robust analytic algorithm that enables the comparison of alphabeta TCR repertoires between individuals and have shown that abnormal alphabeta TCR repertoire is a feature of a subset of patients with advanced MDS.

Unimpaired terminal erythroid differentiation and preserved enucleation capacity in myelodysplastic 5q(del) clones: a single cell study

BACKGROUND

Anemia is a characteristic of myelodysplastic syndromes, such as the rare 5q- syndrome, but its mechanism remains unclear. In particular, data are lacking on the terminal phase of differentiation of erythroid cells (enucleation) in myelodysplastic syndromes.

DESIGN AND METHODS

We used a previously published culture model to generate mature red blood cells in vitro from human hematopoietic progenitor cells in order to study the pathophysiology of the 5q- syndrome. Our model enables analysis of cell proliferation and differentiation at a single cell level and determination of the enucleation capacity of erythroid precursors.

RESULTS

The erythroid commitment of 5q(del) clones was not altered and their terminal differentiation capacity was preserved since they achieved final erythroid maturation (enucleation stage). The drop in red blood cell production was secondary to the decrease in the erythroid progenitor cell pool and to impaired proliferative capacity. RPS14 gene haploinsufficiency was related to defective erythroid proliferation but not to differentiation capacity.

CONCLUSIONS

The 5q- syndrome should be considered a quantitative rather than qualitative bone marrow defect. This observation might open the way to new therapeutic concepts.

Altered naive and memory CD4+ T-cell homeostasis and immunosenescence characterize younger patients with myelodysplastic syndrome

Response to immunosuppressive therapy (IST) in younger patients with myelodysplastic syndrome (MDS) has been linked to a T-cell-dominant autoimmune process that impairs hematopoiesis. Analysis of the age-adjusted CD4:CD8 ratio in 76 MDS patients compared with 54 healthy controls showed that inadequate CD4+, rather than expansion of CD8+ T cells, was associated with a lower ratio in a group that included both lower and higher risk MDS patients defined by the International Prognostic Scoring System. In younger MDS patients, naive and memory phenotypes defined by CD45RA and CD62L display showed depletion of naive CD4+ and CD8+ T cells, suggesting a possible relationship to IST responsiveness. To determine the correlation between T-cell subset distribution, T-cell turnover and autoimmunity, a cohort of 20 patients were studied before and after IST. The CD4:CD8 ratio correlated inversely with the proliferative T-cell index before treatment in IST-responsive patients, suggesting that proliferation may be linked to accelerated CD4+ T-cell turnover and hematopoietic failure. Our data show seminal findings that both CD4+ and CD8+ T-cell subsets are dysregulated in MDS. Association between these T-cell defects and response to IST suggests that aberrant T-cell homeostasis and chronic activation are critical determinants influencing autoimmune hematopoietic suppression in younger patients.

Myelodysplastic syndromes: biology and treatment

Optimal management of patients with myelodysplastic syndromes (MDS) requires an insight into the biology of the disease and the mechanisms of action of the available therapies. This review focuses on low-risk MDS, for which chronic anaemia and eventual progression to acute myeloid leukaemia are the main concerns. We cover the updated World Health Organization classification, the latest prognostic scoring system, and describe novel findings in the pathogenesis of 5q- syndrome. We perform in depth analyses of two of the most widely used treatments, erythropoietin and lenalidomide, discussing mechanisms of action, reasons for treatment failure and influence on survival.

Immune mediated autologous cytotoxicity against hematopoietic precursor cells in patients with myelodysplastic syndrome

BACKGROUND

An activated immune system has been observed in patients with myelodysplastic syndrome but its exact contribution to disease development and control is not fully clarified. On the one hand an activated and skewed T-cell repertoire has been reported, but on the other hand, decreased natural killer cell function has been found. Immune activation could reflect undesired autoimmune reactions against normal hematopoietic precursor cells as well as effective immune-surveillance against dysplastic clones.

DESIGN AND METHODS

We have investigated immune effector cells (lymphocyte subsets, lymphocyte activation markers, and natural killer cells) of 40 low and intermediate risk myelodysplastic syndrome patients and compared them to those of 10 age-matched healthy donors. Furthermore, we have analyzed the cytotoxic capacity of effector cells against autologous bone marrow hematopoietic precursor cells of 8 myelodysplastic syndrome patients and 2 healthy donors.

RESULTS

In myelodysplastic syndrome patients, we have found an activated state of lymphocytes, determined by increased percentages of effector T cells with cytotoxic profile, more skewing of the T-cell receptor Vbeta (TCR-Vbeta) repertoire, and decreased frequencies of regulatory T cells, when compared to healthy donors. The percentage of natural killer cells did not differ between myelodysplastic syndrome patients and healthy donors, but natural killer cells of myelodysplastic syndrome patients expressed increased levels of granzyme B. Finally, we have demonstrated non-MHC restricted autologous cytotoxicity up to 90% against aberrant hematopoietic precursor cells, presumably mediated by natural killer cells.

CONCLUSIONS

Our data point to a role for active immune-surveillance in myelodysplastic syndrome, as demonstrated by activated T cells and TCR-Vss skewing. Autologous cytotoxicity against hematopoietic precursor cells was natural killer cell dependent, which points to an additional role for the innate immune system in immune-surveillance of myelodysplastic syndrome patients.