Deviation of type I and type II T cells and its negative effect on hematopoiesis in myelodysplastic syndrome

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.

The Rising Era of Immune Checkpoint Inhibitors in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of diseases characterized by ineffective hematopoiesis and a wide spectrum of manifestations ranging from indolent and asymptomatic cytopenias to acute myeloid leukemia (AML). MDS result from genetic and epigenetic derangements in clonal cells and their surrounding microenvironments. Studies have shown associations between MDS and other autoimmune diseases. Several immune mechanisms have been identified in MDS, suggesting that immune dysregulation might be at least partially implicated in its pathogenesis. This has led to rigorous investigations on the role of immunomodulatory drugs as potential treatment options. Epigenetic modification via immune check point inhibition, while well established as a treatment method for advanced solid tumors, is a new approach being considered in hematologic malignancies including high risk MDS. Several trials are looking at the efficacy of these agents in MDS, as frontline therapy and in relapse, both as monotherapy and in combination with other drugs. In this review, we explore the utility of immune checkpoint inhibitors in MDS and current research evaluating their efficacy.

Th17 Cells Exhibit Antitumor Effects in MDS Possibly through Augmenting Functions of CD8+ T Cells

Th17 cells are a newly found subset of distinct CD4+ Th effector cells' family and are found to play an important role in cancers. Myelodysplastic syndromes (MDS) are a common malignant hematological disease. Here, we showed that both the percentage and the function of Th17 cells were elevated in low-risk MDS while being decreased in high-risk MDS. Levels of upstream molecules of Th17 cells, IL-6 and IL-23, were higher in low-risk MDS but lower in high-risk MDS patients. The abnormal percentage of Th17 cells was closely related to clinical parameters including karyotype, morphologic blast percentage of bone marrow, peripheral absolute neutrophil count, and hemoglobin concentration. Furthermore, expression rates of perforin and granzyme B in BM CD3+CD8+ cells (cytotoxic T lymphocyte, CTL) positively correlated with levels of IL-17 but negatively correlated with BM blast percentage and could be significantly increased after stimulation with human recombinant IL-17 (rhIL-17). Our results suggested that Th17 cells might play an antitumor effect in the pathogenesis of MDS through IL-17/CTL pathway.

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 Systemic Profile of Soluble Immune Mediators in Patients with Myelodysplastic Syndromes

Introduction: Myelodysplastic syndromes (MDS) are characterized by bone marrow failure due to disturbed bone marrow maturation. MDS is associated with increased risk of transformation to acute myeloid leukemia (AML) and features of immunological dysregulation. Materials and methods: Serum levels of 47 soluble immune mediators were examined in samples derived from 49 MDS patients (35 low-risk and 14 high-risk) and 23 healthy adults. Our patients represent an unselected population-based cohort. The mediators included cytokines, soluble adhesion proteins, matrix metalloproteases, and tissue inhibitors of proteases. Levels were determined using Luminex assays. Patients were classified as low- and high-risk based on the international prognostic scoring system (IPSS) score. Results: When comparing the serum levels of single mediators the MDS patients showed a relatively wide variation range for several mediators compared with healthy adults, especially interleukin 6 (IL-6), IL-8/CXCL8, CCL3, and CCL4. The high-risk patients had lower levels of epidermal growth factor (EGF), cluster of differentiation 40 ligand (CD40L), CCL5, CCL11, CXCL5, matrix metalloproteinase 1 (MMP-1), MMP-9, and tissue inhibitor of metalloproteinases 2 (TIMP-2) compared with low-risk patients. Unsupervised hierarchical cluster analysis visualized marked serum mediator profile differences between MDS patients; based on this analysis three patient subsets could be identified. The healthy adults were also included in this analysis and, as expected, they formed their own separate cluster, except for one outlier. Both low- and high-risk patients showed considerable heterogeneity with regard to serum profile, and this heterogeneity seems stable over time (one year follow-up). Finally, very few mediators differed between low- and high-risk patients, but hierarchical clustering based both on all mediators, as well as five selected mediators (EGF, CCL11, TIMP-2, MMP-1, and MMP-9) identified subsets of patients with significantly increased frequency of high-risk disease (χ-square test p = 0.0158 and p = 0.0148).

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.

Th2 lymphocytes migrating to the bone marrow under high-altitude hypoxia promote erythropoiesis via activin A and interleukin-9

The mechanism of accelerated erythropoiesis under the hypoxic conditions of high altitude (HA) remains largely obscure. Here, we investigated the potential role of bone marrow (BM) T cells in the increased production of erythrocytes at HA. We found that mice exposed to a simulated altitude of 6,000 m for 1-3 weeks exhibited a significant expansion of BM CD4+ cells, mainly caused by increasing T helper 2 (Th2) cells. Using a coculture model of BM T cells and hematopoietic stem/progenitor cells, we observed that BM CD4+ cells from hypoxic mice induced erythroid output more easily, in agreement with the erythroid-enhancing effect observed for Th2-condition-cultured BM CD4+ cells. It was further demonstrated that elevated secretion of activin A and interleukin-9 by BM Th2 cells of hypoxic mice promoted erythroid differentiation of hematopoietic stem/progenitor cells and the growth of erythroblasts, respectively. Our study also provided evidence that the CXCL12-CXCR4 interaction played an important role in Th2 cell trafficking to the BM under HA conditions. These results collectively suggest that Th2 cells migrating to the BM during HA exposure have a regulatory role in erythropoiesis, which provides new insight into the mechanism of high altitude polycythemia.

Distinct clinical and experimental characteristics in the patients younger than 60 years old with myelodysplastic syndromes

Myelodysplastic syndromes (MDS) mainly occur in elderly individuals in Western countries. However, MDS is commonly found in young individuals (<60 years) in Asia. The reason for the high incidence in younger individuals is still unclear, and the differences in disease features between young and elderly patients with MDS have been not well recognized. To explore these issues, in this study, we analyzed the clinical and experimental characteristics of MDS in the patients younger and older than 60 years old and characterized the potential age-associated differences. The results showed that over half of the patients with MDS (61.9%) were younger than 60 years old upon the first diagnosis. The younger patients were more likely to be female, who have lower risk and less advanced MDS. The occurrence of trisomy 8 and bone marrow failure were more frequent in the younger patients than the older ones. The marrow CD34+ cells in the younger patients showed lower proliferation and higher apoptosis in comparison with that in the older ones. Obvious amplification of T cells and low CFU formation could be found in the younger patients. CFU formation was significantly increased in the younger patients after the removal of activated T cells. In addition, the younger patients had a lower frequency of p15^INK4B methylation, longer survival expectancy and less AML transformation. In summary, the younger patients with MDS in China may show more benign disease features than the older ones. Enhanced immunological response may be involved in the pathogenesis of MDS in the patients younger than 60 years.

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.

The use of selective immunosuppressive therapy on myelodysplastic syndromes in targeted populations results in good response rates and avoids treatment-related disease progression

To determine the treatment response and disease progression in strictly selected patients with myelodysplastic syndrome undergoing immunosuppressive therapy (IST), patients were required to have an international prognostic scoring system [corrected] (IPSS) score ≤ 1.0 and at least one of the following conditions: (1) expression of the HLA-DR15 allele, (2) bone marrow (BM) cellularity of less than 30%, and (3) abnormal immune index of BM T-lymphocytes.The exclusion criteria were as follows: (1) ≥ 5% marrow myeloblasts, (2) poor karyotype, and (3) diagnosis of concurrent nonhematological malignancy. Patients received antithymocyte globulin followed by cyclosporine A (CsA) or CsA alone for at least 3 months. Seventy-one cases were analyzed. The total response rate was 77.5% (55/71 cases) with 11 complete responses. The response rate was positively correlated with the number of recruitment criteria met. Patients with an abnormal CD8, an abnormal CD4, or both had similar response rates. Patients who responded to treatment had significantly lower Th1 and Tc1 levels after treatment (P < 0.01 and P < 0.001, respectively), and six of eight patients with abnormal chromosomes did not show obviously abnormal clonal expansion when reassessed after IST. During the median observation period of 24 months, only two cases exhibited disease progression. At the median observation of 24 months, 35 of 55 responders (63.6%) maintained a hematological response, and 60 of 71 patients (84.5%) were still alive. The strictly selective use of IST may yield high response rates and can avoid treatment-related acute myeloid leukemia transformation. IST significantly reduces Th1 and Tc1 levels without causing malignant clonal expansion.

Comparison of immunological abnormalities of lymphocytes in bone marrow in myelodysplastic syndrome (MDS) and aplastic anemia (AA)

OBJECTIVE

The subsets and the polarization of lymphocytes in bone marrow from low-risk myelodysplastic syndrome (MDS) were studied and compared with those from patients with aplastic anemia (AA).

METHODS

A total of 34 patients with low-risk MDS (IPSS score< or =1.0) who presented abnormal chromosomes and 16 patients with AA were enrolled in this study. We determined T lymphocyte subsets, T cells polarization status, and the percentages of NK cells and of B lymphocytes in bone marrow and compared these parameters between the two groups of patients. As controls, 24 patients with high-risk MDS (IPSS score>1.0) presenting abnormal chromosomes and 22 healthy/benign hematologic disease subjects were used.

RESULTS

In low-risk MDS/AA patients, the percentage of CD3+ lymphocytes was significantly increased compared to controls (p=0.006 and p=0.001), while the percentage of CD19+ lymphocytes was significantly decreased (p<0.001 and p=0.002); there were no significant differences between MDS/AA and normal controls in other parameters; For low-risk MDS patients, the polarization status of bone marrow CD4+ cells toward Th1 (Th1/Th2) and of CD8+ cells toward Tc1 (Tc1/Tc2) was stronger than that for AA patients (p=0.05 and p<0.001). Other parameters did not show significant differences; Regardless of the predominance of CD4 or CD8 T cells, all patients with low-risk MDS were accompanied with elevated Tc1 polarization (Tc1/Tc2).

CONCLUSION

In both AA and MDS, the number of total T lymphocytes increased. However, polarization towards Th1 and Tc1 was obviously stronger in MDS patients than in AA patients. This might be related to T cell stimulation from the clones of malignant hematopoietic cells.