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Immunosuppressive role of CD11b+ CD33+ HLA-DR- myeloid-derived suppressor cells-like blast subpopulation in acute myeloid leukemia.

ABSTRACT: OBJECTIVE:Myeloid-derived suppressor cells (MDSCs) facilitate tumor growth and development by suppressing T cell function; however, their role in acute myeloid leukemia (AML) remains unclear. Here, we investigated the immunosuppressive role and prognostic value of blasts with an MDSC-like phenotype. METHODS:CD11b+ CD33+ HLA-DR- MDSC-like blasts from bone marrow mononuclear cells of patients with AML were analyzed. To investigate their T cell-suppressing function, MDSC-like blasts were isolated using flow cytometry and co-cultured with CD8+ cytotoxic T cells and NB4 leukemic cells. Treatment outcomes were then compared between the MDSC-like blasts low (?9.76%) and high (>9.76%) groups to identify clinical significance. RESULTS:MDSC-like blasts showed higher expression of arginase-1 and inducible nitric oxide synthase. Isolated MDSC-like blasts significantly suppressed CD8+ T cell proliferation induced by phytohemagglutinin A. NB4 cell proliferation was significantly suppressed upon co-culture with CD8+ cytotoxic T cells and partially restored upon co-culture with MDSC-like blasts. Patients with high MDSC-like blasts at diagnosis showed substantially shorter overall survival and leukemia-free survival relative to low MDSC-like blasts patients, with subgroup analysis showing statistically significant differences in patients not receiving allogeneic hematopoietic stem cell transplantation. CONCLUSION:We demonstrated that MDSC-like blasts drive AML-specific immune-escape mechanisms by suppressing T cell proliferation and restoring T cell-suppressed NB4 cell proliferation, with clinically higher fractions of MDSC-like blasts at diagnosis resulting in poor prognosis.

SUBMITTER: Hyun SY

PROVIDER: S-EPMC7541151 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Immunosuppressive role of CD11b<sup>+</sup> CD33<sup>+</sup> HLA-DR<sup>-</sup> myeloid-derived suppressor cells-like blast subpopulation in acute myeloid leukemia.

Hyun Shin Young SY Na Eun Jung EJ Jang Ji Eun JE Chung Haerim H Kim Soo Jeong SJ Kim Jin Seok JS Kong Jee Hyun JH Shim Kwang Yong KY Lee Jong In JI Min Yoo Hong YH Cheong June-Won JW

Cancer medicine 20200811 19

<h4>Objective</h4>Myeloid-derived suppressor cells (MDSCs) facilitate tumor growth and development by suppressing T cell function; however, their role in acute myeloid leukemia (AML) remains unclear. Here, we investigated the immunosuppressive role and prognostic value of blasts with an MDSC-like phenotype.<h4>Methods</h4>CD11b<sup>+</sup> CD33<sup>+</sup> HLA-DR<sup>-</sup> MDSC-like blasts from bone marrow mononuclear cells of patients with AML were analyzed. To investigate their T cell-suppre ...[more]

PMID: 32780544

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Project description:ObjectiveImmature CD11b + Gr1+ myeloid cells that acquire immunosuppressive capability, also known as myeloid-derived suppressor cells (MDSCs), are a heterogeneous population of cells that regulate immune responses. Our study's objective was to elucidate the role of ovarian cancer microenvironment in regulating the immunosuppressive function of CD11b+Gr1+ myeloid cells.MethodsAll studies were performed using the intraperitoneal ID8 syngeneic epithelial ovarian cancer mouse model. Myeloid cell depletion and immunotherapy were carried out using anti-Gr1 mAb, gemcitabine treatments, and/or anti-PD1 mAb. The treatment effect was assessed by a survival curve, in situ luciferase-guided imaging, and histopathologic evaluation. Adoptive transfer assays were carried out between congenic CD45.2 and CD45.1 mice. Immune surface and intracellular markers were assessed by flow cytometry. ELISA, western blot, and RT-PCR techniques were employed to assess the protein and RNA expression of various markers. Bone marrow-derived myeloid cells were used for ex-vivo studies.ResultsThe depletion of Gr1+ immunosuppressive myeloid cells alone and in combination with anti-PD1 immunotherapy inhibited ovarian cancer growth. In addition to the adoptive transfer studies, these findings validate the role of immunosuppressive CD11b+Gr1+ myeloid cells in promoting ovarian cancer. Mechanistic investigations showed that ID8 tumor cells and their microenvironments produced recruitment and regulatory factors for immunosuppressive CD11b+Gr1+ myeloid cells. CD11b+Gr1+ myeloid cells primed by ID8 tumors showed increased immunosuppressive marker expression and acquired an energetic metabolic phenotype promoted primarily by increased oxidative phosphorylation fueled by glutamine. Inhibiting the glutamine metabolic pathway reduced the increased oxidative phosphorylation and decreased immunosuppressive markers' expression and function. Dihydrolipoamide succinyl transferase (DLST), a subunit of α-KGDC in the TCA cycle, was found to be the most significantly elevated gene in tumor-primed myeloid cells. The inhibition of DLST reduced oxidative phosphorylation, immunosuppressive marker expression and function in myeloid cells.ConclusionOur study shows that the ovarian cancer microenvironment can regulate the metabolism and function of immunosuppressive CD11b + Gr1+ myeloid cells and modulate its immune microenvironment. Targeting glutamine metabolism via DLST in immunosuppressive myeloid cells decreased their activity, leading to a reduction in the immunosuppressive tumor microenvironment. Thus, targeting glutamine metabolism has the potential to enhance the success of immunotherapy in ovarian cancer.

Project description:BackgroundSustained yet intractable immunosuppression is commonly observed in septic patients, resulting in aggravated clinical outcomes. However, due to the substantial heterogeneity within septic patients, precise indicators in deciphering clinical trajectories and immunological alterations for septic patients remain largely lacking.MethodsWe adopted cross-species, single-cell RNA sequencing (scRNA-seq) analysis based on two published datasets containing circulating immune cell profile of septic patients as well as immune cell atlas of murine model of sepsis. Flow cytometry, laser scanning confocal microscopy (LSCM) imaging and Western blotting were applied to identify the presence of S100A9+ monocytes at protein level. To interrogate the immunosuppressive function of this subset, splenic monocytes isolated from septic wild-type or S100a9-/- mice were co-cultured with naïve CD4+ T cells, followed by proliferative assay. Pharmacological inhibition of S100A9 was implemented using Paquinimod via oral gavage.ResultsScRNA-seq analysis of human sepsis revealed substantial heterogeneity in monocyte compartments following the onset of sepsis, for which distinct monocyte subsets were enriched in disparate subclusters of septic patients. We identified a unique monocyte subset characterized by high expression of S100A family genes and low expression of human leukocyte antigen DR (HLA-DR), which were prominently enriched in septic patients and might exert immunosuppressive function. By combining single-cell transcriptomics of murine model of sepsis with in vivo experiments, we uncovered a similar subtype of monocyte significantly associated with late sepsis and immunocompromised status of septic mice, corresponding to HLA-DRlowS100Ahigh monocytes in human sepsis. Moreover, we found that S100A9+ monocytes exhibited profound immunosuppressive function on CD4+ T cell immune response and blockade of S100A9 using Paquinimod could partially reverse sepsis-induced immunosuppression.ConclusionsThis study identifies HLA-DRlowS100Ahigh monocytes correlated with immunosuppressive state upon septic challenge, inhibition of which can markedly mitigate sepsis-induced immune depression, thereby providing a novel therapeutic strategy for the management of sepsis.

Dataset Information

Immunosuppressive role of CD11b+ CD33+ HLA-DR- myeloid-derived suppressor cells-like blast subpopulation in acute myeloid leukemia.

Publications

Immunosuppressive role of CD11b<sup>+</sup> CD33<sup>+</sup> HLA-DR<sup>-</sup> myeloid-derived suppressor cells-like blast subpopulation in acute myeloid leukemia.

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