Monocytes are activated in patients with myelodysplastic syndromes and can contribute to bone marrow failure through CD40–CD40L interactions with T helper cells

The immunoregulatory role of monocytes and thrombomodulin in myelodysplastic neoplasms

Myelodysplastic neoplasms (MDS) are clonal disorders of the myeloid lineage leading to peripheral blood cytopenias. Dysregulation of innate immunity is hypothesized to be a potent driver of MDS. A recent study revealed increased thrombomodulin (TM) expression on classical monocytes in MDS, which was associated with prolonged survival. TM is a receptor with immunoregulatory capacities, however, its exact role in MDS development remains to be elucidated. In this review we focus on normal monocyte biology and report on the involvement of monocytes in myeloid disease entities with a special focus on MDS. Furthermore, we delve into the current knowledge on TM and its function in monocytes in health and disease and explore the role of TM-expressing monocytes as driver, supporter or epiphenomenon in the MDS bone marrow environment.

Immune-monitoring of myelodysplastic neoplasms: Recommendations from the i4MDS consortium

Advancements in comprehending myelodysplastic neoplasms (MDS) have unfolded significantly in recent years, elucidating a myriad of cellular and molecular underpinnings integral to disease progression. While molecular inclusions into prognostic models have substantively advanced risk stratification, recent revelations have emphasized the pivotal role of immune dysregulation within the bone marrow milieu during MDS evolution. Nonetheless, immunotherapy for MDS has not experienced breakthroughs seen in other malignancies, partly attributable to the absence of an immune classification that could stratify patients toward optimally targeted immunotherapeutic approaches. A pivotal obstacle to establishing "immune classes" among MDS patients is the absence of validated accepted immune panels suitable for routine application in clinical laboratories. In response, we formed International Integrative Innovative Immunology for MDS (i4MDS), a consortium of multidisciplinary experts, and created the following recommendations for standardized methodologies to monitor immune responses in MDS. A central goal of i4MDS is the development of an immune score that could be incorporated into current clinical risk stratification models. This position paper first consolidates current knowledge on MDS immunology. Subsequently, in collaboration with clinical and laboratory specialists, we introduce flow cytometry panels and cytokine assays, meticulously devised for clinical laboratories, aiming to monitor the immune status of MDS patients, evaluating both immune fitness and identifying potential immune "risk factors." By amalgamating this immunological characterization data and molecular data, we aim to enhance patient stratification, identify predictive markers for treatment responsiveness, and accelerate the development of systems immunology tools and innovative immunotherapies.

Myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a family of myeloid cancers with diverse genotypes and phenotypes characterized by ineffective haematopoiesis and risk of transformation to acute myeloid leukaemia (AML). Some epidemiological data indicate that MDS incidence is increasing in resource-rich regions but this is controversial. Most MDS cases are caused by randomly acquired somatic mutations. In some patients, the phenotype and/or genotype of MDS overlaps with that of bone marrow failure disorders such as aplastic anaemia, paroxysmal nocturnal haemoglobinuria (PNH) and AML. Prognostic systems, such as the revised International Prognostic Scoring System (IPSS-R), provide reasonably accurate predictions of survival at the population level. Therapeutic goals in individuals with lower-risk MDS include improving quality of life and minimizing erythrocyte and platelet transfusions. Therapeutic goals in people with higher-risk MDS include decreasing the risk of AML transformation and prolonging survival. Haematopoietic cell transplantation (HCT) can cure MDS, yet fewer than 10% of affected individuals receive this treatment. However, how, when and in which patients with HCT for MDS should be performed remains controversial, with some studies suggesting HCT is preferred in some individuals with higher-risk MDS. Advances in the understanding of MDS biology offer the prospect of new therapeutic approaches.

Expression of mRNA TNFα and level of protein TNFα after exposure sCD40L in bone marrow mononuclear cells of myelodysplastic syndromes

Background

Cytopenia is the primary phenomenon in myelodysplastic syndrome (MDS) amidst hypercellular bone marrow. The soluble CD40 ligand (sCD40L) is considered as a cytokine that can trigger synthesis of tumor necrosis factor α (TNFα) that promotes apoptosis. The objective of this study is to prove that recombinant human sCD40L (rh-sCD40L) exposure on bone marrow mononuclear cells (BMMC) MDS increases TNFα expression at mRNA level and at protein level.

Methods

BMMC from MDS patients whom diagnosed and classified using the WHO 2008 criteria, were exposed to rh-sCD40L and antiCD40L. The expressions of TNFα mRNAs were quantified by qRT-PCR, level of TNFα were measured using the ELISA method.

Results

Exposure of rh-sCD40L significantly increased the expression of TNFα mRNA. The similar exposure also significantly increased the level of TNFα compared to controls. TNFα mRNA expression on BMMC in MDS samples exposed to rh-sCD40L is 3.32 times compared to TNFα mRNA expression without exposure. level of TNFα in supernatant media exposed to rh-sCD40L in MDS samples was higher than that of control samples which were 44.44 and 4.85 pg/mL, P=0.018.

Conclusions

The sCD40L plays a role in increasing the synthesis of TNFα in mRNA level and protein level in BMMC MDS.

Monocyte function in patients with myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a malignant hematopoietic stem cell disorder that frequently evolves into acute myeloid leukemia (AML). Patients with MDS are prone to infectious complications, in part due to the presence of severe neutropenia and/or neutrophil dysfunction. However, not all patients with neutropenia become infected, suggesting that other immune cells may compensate in these patients. Monocytes are also integral to immunologic defense; however, much less is known about monocyte function in patients with MDS. In the current study, we monitor the composition of peripheral blood monocytes and several aspects of monocyte function in MDS patients, including HLA-DR expression, LPS-induced inflammatory cytokine production, and phagocytosis. We find that monocytes from MDS patients exhibit relatively normal innate immune functions compared to monocytes from healthy control subjects. We also find that HLA-DR expression is moderately increased in monocytes from MDS patients. These results suggest that monocytes could compensate for other immune deficits in MDS patients to help fight infection. We also find that the range of immune functions in monocytes from MDS patients correlates with several key clinical parameters, including blast cell count, monocyte count, and revised International Prognostic Scoring System score, suggesting that disease severity impacts monocyte function in MDS patients.

Multipotent adult progenitor cells improve the hematopoietic function in myelodysplasia

BACKGROUND AIMS

Myelodysplastic syndromes (MDS) are a group of clonal stem cell disorders affecting the normal hematopoietic differentiation process and leading to abnormal maturation and differentiation of all blood cell lineages. Treatment options are limited, and there is an unmet medical need for effective therapies for patients with severe cytopenias.

METHODS

We demonstrate that multipotent adult progenitor cells (MAPC) improve the function of hematopoietic progenitors derived from human MDS bone marrow (BM) by significantly increasing the frequency of primitive progenitors as well as the number of myeloid colonies.

RESULTS

This effect was more pronounced in a non-contact culture, indicating the importance of soluble factors produced by the MAPC cells. Moreover, the cells did not stimulate the growth of the abnormal MDS clone, as shown by fluorescent in situ hybridization analysis on BM cells from patients with a known genetic abnormality. We also demonstrate that MAPC cells can provide stromal support for patient-derived hematopoietic cells. When MAPC cells were intravenously injected into a mouse model of MDS, they migrated to the site of injury and increased the hematopoietic function in diseased mice.

DISCUSSION

The preclinical studies undertaken here indicate an initial proof of concept for the use of MAPC cell therapy in patients with MDS-related severe and symptomatic cytopenias and should pave the way for further investigation in clinical trials.

Autologous bone marrow Th cells can support multiple myeloma cell proliferation in vitro and in xenografted mice

Multiple myeloma (MM) is a plasma cell malignancy where MM cell growth is supported by the bone marrow (BM) microenvironment with poorly defined cellular and molecular mechanisms. MM cells express CD40, a receptor known to activate autocrine secretion of cytokines and elicit proliferation. Activated T helper (Th) cells express CD40 ligand (CD40L) and BM Th cells are significantly increased in MM patients. We hypothesized that activated BM Th cells could support MM cell growth. We here found that activated autologous BM Th cells supported MM cell growth in a contact- and CD40L-dependent manner in vitro. MM cells had retained the ability to activate Th cells that reciprocated and stimulated MM cell proliferation. Autologous BM Th cells supported MM cell growth in xenografted mice and were found in close contact with MM cells. MM cells secreted chemokines that attracted Th cells, secretion was augmented by CD40-stimulation. Within 14 days of culture of whole BM aspirates in autologous serum, MM cells and Th cells mutually stimulated each other, and MM cells required Th cells for further expansion in vitro and in mice. The results suggest that Th cells may support the expansion of MM cells in patients.

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.

The myelodysplastic syndromes: the era of understanding

Myelodysplastic syndromes are a heterogeneous group of clonal haematological stem cell disorders. Allogeneic stem cells transplantation remains the only curative treatment but only a minority of patients are eligible for this treatment. In spite of this, it has become clear that treatment with lenalidomide and azanucleotides can lead to increased overall survival in particular subsets of patients with MDS. The relative silence on the therapeutic side is counter-balanced by major advances in the understanding of this heterogeneous disease. The introduction of high-throughput molecular techniques has resulted in the discovery that most patients harbour molecular aberrations, including pathways such as the spliceosome machinery previously not known to be involved. These newly discovered pathways will undoubtedly result in new therapeutic strategies for this difficult to treat disease.

Role of flow cytometry in diagnostics of myelodysplastic syndromes--beyond the WHO 2008 classification

Multiparameter flow cytometry (FCM) is an excellent method to follow the expression patterns of differentiation antigens using monoclonal antibodies to surface and cytoplasmic proteins. Although several authors described various aberrant immunophenotypic features in the bone marrow of patients with myelodysplastic syndromes (MDS), the World Health Organization 2008 classification recommended that, only if 3 or more phenotypic abnormalities are found involving 1 or more of the myeloid lineages can the aberrant FCM findings be considered suggestive of MDS. In the absence of conclusive morphologic and/or cytogenetic features, FCM abnormalities alone were considered not sufficient to establish MDS diagnosis and further follow-up of the patients was recommended. Review of the literature gives accumulating evidence that FCM has become an important part of the integrated diagnostic work-up of patients with suspected MDS. Several studies have also reported FCM findings significant for prognosis and therapy choice in MDS patients. Technical progress in multicolor FCM and new analysis programs, together with ongoing efforts to standardize the methodology, will make it possible to apply FCM in individual risk assessment and choice of best therapy for MDS patients.

The role of CD40/CD40 ligand interactions in bone marrow granulopoiesis

The CD40 ligand (CD40L) and CD40 are two molecules belonging to the TNF/TNF receptor superfamily, and their role in adaptive immune system has widely been explored. However, the wide range of expression of these molecules on hematopoietic as well as nonhematopoietic cells has revealed multiple functions of the CD40/CD40L interactions on different cell types and processes such as granulopoiesis. CD40 triggering on stromal cells has been documented to enhance the expression of granulopoiesis growth factors such as granulocyte-colony-stimulating factor (G-CSF) and granulocyte/monocyte-colony-stimulating factor (GM-CSF), and upon disruption of the CD40/CD40L-signaling pathway, as in the case of X-linked hyperimmunoglobulin M (IgM) syndrome (XHIGM), it can lead to neutropenia. In chronic idiopathic neutropenia (CIN) of adults, however, under the influence of an inflammatory microenvironment, CD40L plays a role in granulocytic progenitor cell depletion, providing thus a pathogenetic cause of CIN.

The clonogenic potential of selected CD34+ cells from patients with MDS appear preserved when tested ex vivo

Our aim was to examine in 17 patients with MDS the effects of PMA activated and non-activated autologous lymphocytes on selected bone marrow CD34+ progenitors, in dose response studies. We used a double layer culture technique. Compared with controls, there was no difference in the colony growth promoting capacity of autologous PMA stimulated or unstimulated blood lymphocytes from MDS patients. In addition, similar to control studies, increasing numbers of lymphocytes, (0, 1×10(5), 1×10(6)) led to a corresponding increase in the number of CFU-GM (p=0.04). We conclude that MDS blood mononuclear cells have the ability to stimulate colony growth of autologous CD34+ cells while these selected progenitors show a proliferative capacity that is similar to normal when they are isolated from the bone marrow accessory cells.

Immune alterations in untreated and treated myelodysplastic syndrome

INTRODUCTION

Current literature suggests a variety of immune abnormalities are present in myelodysplastic syndrome (MDS) patients. However, they have not been comprehensively characterized or systematized to date. As a result, their clinical implications remain largely unknown. In addition, an increased incidence of various autoimmune conditions has been documented in MDS patients.

AREAS COVERED

The authors offer a comprehensive review of the existing literature on immune mechanisms involved in the pathogenesis of MDS, various immune abnormalities documented in its course, their link with the clonal evolution of MDS as well as immune alterations induced by the existing MDS therapies.

EXPERT OPINION

The course of MDS is accompanied by complex immune alterations, including T-cell and NK-cell defects, decreased functional abilities of neutrophils and antigen-presenting cells, altered antibody and cytokine production. While contemporary MDS therapies are shown to possess some immunomodulatory properties, authentic autoimmune conditions have also been documented with lenalidomide and recombinant erythropoietin. Caution should be exerted with the use of these agents in MDS patients with evidence of autoimmune disorders, as exacerbation of autoimmune phenomena can be anticipated. While the heterogeneity of MDS represents an inherent limitation, integration of emerging information from molecular biology, genetics, immunology research and clinical practice could translate into improved outcomes of this disease spectrum.

Maintenance treatment with azacytidine for patients with high-risk myelodysplastic syndromes (MDS) or acute myeloid leukaemia following MDS in complete remission after induction chemotherapy

This prospective Phase II study is the first to assess the feasibility and efficacy of maintenance 5-azacytidine for older patients with high-risk myelodysplastic syndrome (MDS), chronic myelomonocytic leukaemia and MDS-acute myeloid leukaemia syndromes in complete remission (CR) after induction chemotherapy. Sixty patients were enrolled and treated by standard induction chemotherapy. Patients that reached CR started maintenance therapy with subcutaneous azacytidine, 5/28 d until relapse. Promoter-methylation status of CDKN2B (P15 ink4b), CDH1 and HIC1 was examined pre-induction, in CR and 6, 12 and 24 months post CR. Twenty-four (40%) patients achieved CR after induction chemotherapy and 23 started maintenance treatment with azacytidine. Median CR duration was 13.5 months, >24 months in 17% of the patients, and 18-30.5 months in the four patients with trisomy 8. CR duration was not associated with CDKN2B methylation status or karyotype. Median overall survival was 20 months. Hypermethylation of CDH1 was significantly associated with low CR rate, early relapse, and short overall survival (P = 0.003). 5-azacytidine treatment, at a dose of 60 mg/m(2) was well tolerated. Grade III-IV thrombocytopenia and neutropenia occurred after 9.5 and 30% of the cycles, respectively, while haemoglobin levels increased during treatment. 5-azacytidine treatment is safe, feasible and may be of benefit in a subset of patients.

Anti-moesin antibodies derived from patients with aplastic anemia stimulate monocytic cells to secrete TNF-alpha through an ERK1/2-dependent pathway

Antibodies specific to moesin, which are frequently detectable in the serum of patients with aplastic anemia (AA), can induce tumor necrosis factor-alpha (TNF-alpha) secretion from monocytes and a human monocytic leukemia cell line THP-1. We investigated the mechanisms responsible for TNF-alpha secretion from monocytic cells induced by the auto-antibodies that are purified from the sera of AA patients. TNF-alpha induction by anti-moesin antibodies depended on the amount of cell surface moesin expressed by THP-1 cells. F(ab')(2) fragments prepared from the anti-moesin antibodies were able to stimulate THP-1 cells to secrete TNF-alpha and this stimulatory effect was enhanced by cross-linking of moesins with anti-human IgG F(ab')(2) fragment antibodies. Anti-moesin antibodies as well as their F(ab')(2) fragments induced the phosphorylation of ERK1/2 in monocytic cells and this effect was suppressed by the addition of an ERK1/2 inhibitor. Moreover, anti-moesin antibody treatment induced the phosphorylation of moesin proteins in the monocytes and THP-1 cells within 30 min. These results indicate that anti-moesin antibodies induce TNF-alpha secretion from monocytes through the activation of the ERK1/2 pathway provoked by direct binding to moesin on the cells.