B cells provide humoral immunity by differentiating into antibody-secreting plasma cells, a process that requires cell division and is linked to DNA hypomethylation and gene regulation. Conversely, accumulation of DNA methylation in B cell differentiation is less apparent. To determine the role of de novo DNA methylation in B cell differentiation, the de novo DNA methyltransferases, Dnmt3a and Dnmt3b, were deleted in B cells resulting in phenotypically normal B cell development in the bone marrow, spleen and lymph nodes. However, upon immunologic challenge, mice deficient for Dnmt3a and Dnmt3b (Dnmt3-deficient) accumulated more antigen-specific B cells and bone marrow chimeras showed this was cell-autonomous. Additionally, a five-fold increase in splenic and bone marrow plasma cells was observed. Molecular analysis revealed that Dnmt3-deficient bone marrow plasma cells failed to repress gene expression to the same level as their Dnmt3ab-sufficient counterparts. This was coupled with a failure of Dnmt3-deficient germinal center B cells and plasma cells to gain and/or maintain DNA methylation at several thousand loci that were clustered in enhancers of genes that function in B cell activation and homing. Analysis of chromatin accessibility showed Dnmt3-deficient plasma cells had increased accessibility at several genes involved in hematopoiesis and B cell differentiation. These data show that de novo DNA methylation limits B cell activation, proliferation and differentiation, and support a model whereby DNA methylation represses the aberrant transcription of genes silenced in B cell differentiation to maintain plasma cell homeostasis. Overall design: Naïve lymph node B cells (B220+ GL7- Fas-), Phycoerythrin-specific germinal center B cells (B220+ GL7+ Fas+ PE+), and bone marrow plasma cells (CD138+) were compared between Cd19cre/wtDnmt3afl/flDnmt3bfl/fl (Dnmt3-deficient) and littermate control Cd19wt/wtDnmt3afl/flDnmt3bfl/fl (Dnmt3-sufficient) mice using RRBS, RNA-seq, and ATAC-seq. Naïve lymph node B cells were taken from naïve mice, whereas PE-specific germinal center B cells and bone marrow plasma cells were isolated from mice that had been immunized with phycoerythrin 30 days prior. This Series includes the RNA-seq component of the study.
B cell activation and plasma cell differentiation are inhibited by de novo DNA methylation.
Sex, Specimen part, Subject
View SamplesThe goal of this project is to identify genes preferentially expressed in inflammatory macrophages as compared with control macrophages.
Cutting Edge: IL-36 Receptor Promotes Resolution of Intestinal Damage.
Specimen part, Treatment
View SamplesAcute myeloid leukemia (AML) is a heterogeneous disease and AML with normal karyotype (AML-NK) is categorized as an intermediate-risk group. Over the past years molecular analyses successfully identified biomarkers that will further allow to dissecting clinically meaningful subgroups in this disease. Thus far, somatic mutations were identified which elucidate the disturbance of cellular growth, proliferation, and differentiation processes in hematopoietic progenitor cells. In AML-NK, acquired gene mutations with prognostic relevance were identified for FLT3, CEBPA, and NPM1. FLT3-ITD mutations were associated with short relapse-free and overall survival, while mutations in CEBPA or NPM1 (without concomitant FLT3-ITD) had a more favorable outcome.
Quantitative comparison of microarray experiments with published leukemia related gene expression signatures.
Sex, Age, Disease, Disease stage
View SamplesMicroarray gene expression (MAGE) signatures allow insights into the transcriptional processes of leukemias and may evolve as a molecular diagnostic test. Introduction of MAGE into clinical practice of leukemia diagnosis will require comprehensive assessment of variation due to the methodologies.
New data on robustness of gene expression signatures in leukemia: comparison of three distinct total RNA preparation procedures.
No sample metadata fields
View SamplesThe clinical course of patients with chronic lymphocytic leukemia (CLL) is heterogeneous. Several prognostic factors have been identified that can stratify patients into groups that differ in their relative tendency for disease progression and/or survival. Here, we pursued a subnetwork-based analysis of gene expression profiles to discriminate between groups of patients with disparate risks for CLL progression.
Subnetwork-based analysis of chronic lymphocytic leukemia identifies pathways that associate with disease progression.
Specimen part
View SamplesThe clinical impact of aberrant CEBPA promoter methylation (PM) in AML is controversial discussed. The aim of this study was to clarify the significance of aberrant CEBPA PM with regard to clinical features in a cohort of 572 de novo AML with wildtype CEBPA and normal karyotype. The distal promoter was methylated in 54/572 cases (9.41%) whereas proximal PM was never detected. Methylation of the core promoter was detected in only 8 of 326 cases (2.45%) and thus seems to be a rare event in AML. There was no correlation between CEBPA distal PM, age, sex, white blood cell (WBC) count or Hb levels at diagnosis. We also were not able to detect a significant correlation between the presence of CEBPA distal PM and molecular mutations such as FLT3-ITD, NPM1, AML1, MLL-PTD and IDH1. Solely the frequency of IDH2R140 mutations was significantly reduced in CEBPA distal PM positive compared to CEBPA distal PM negative cases (p=0.01). Furthermore, analysis of CEBPA mRNA expression level revealed no difference between CEBPA distal PM positive and CEBPA distal PM negative cases, suggesting that CEBPA distal PM has no influence on CEBPA expression. CEBPA distal PM did not show impact on overall survival (OS), event free survival (EFS) or incidence of relapse. Also when other mutations were taken into regard no prognostic impact of CEBPA distal PM could be shown. In contrast, a distinct expression profile of CEBPA distal PM positive cases compared to CEBPA mutated and CEBPA distal PM negative cases was observed. In addition, a significantly higher frequency of CEBPA distal PM was detected in RUNX1-RUNX1T1 positive AML compared to the CEBPA witdtype cases. We conclude that the presence of aberrant CEBPA PM has no clinical relevance and is therefore a negligible prognostic marker in de novo AML with normal karyotype.
Frequency and prognostic impact of CEBPA proximal, distal and core promoter methylation in normal karyotype AML: a study on 623 cases.
Disease
View SamplesMicroarray-based classifiers and prognosis models identify subgroups with distinct clinical outcomes and high risk of AML transformation of myelodysplastic syndrome (MDS)
Microarray-based classifiers and prognosis models identify subgroups with distinct clinical outcomes and high risk of AML transformation of myelodysplastic syndrome.
Disease, Disease stage
View SamplesFull Title: Multilineage Dysplasia (MLD) in AML correlates with MDS-related cytogenetic abnormalities and a prior history of MDS or MDS/MPN but has no independent prognostic relevance: A comparison of 408 cases classified as AML not otherwise specified or AML with myelodysplasia-related changes
Multilineage dysplasia (MLD) in acute myeloid leukemia (AML) correlates with MDS-related cytogenetic abnormalities and a prior history of MDS or MDS/MPN but has no independent prognostic relevance: a comparison of 408 cases classified as "AML not otherwise specified" (AML-NOS) or "AML with myelodysplasia-related changes" (AML-MRC).
No sample metadata fields
View SamplesBy WHO 2008, CEBPA-mutated AML became a provisional subentity, but it remains to be clarified how CEBPAmut AML with multilineage dysplasia (MLD; 50% dysplastic cells in 2-3 lineages) but no other MDS-related feature should be classified. We investigated 108 CEBPAmut AML (15.7-87.6 years) for the impact of MLD and genetic features. MLD-positive patients differed from MLD-negative only by lower mean WBC counts (p=0.004), but not by other blood values, biologic characteristics, cytogenetic risk profiles, or additional molecular markers (NPM1mut, FLT3-ITD/TKD, RUNX1, MLL-PTD, IDH1/2). Biallelic CEBPAmut differed from wild-type-cases by differential expression of 213 genes, but did not differ significantly between MLD-positive/-negative patients. Survival outcomes were improved for females and those <60 years, intermediate versus adverse karyotypes (p=0.021), and for biallelic versus monoallelic/homozygous CEBPAmut (p=0.060) in case of FLT3-ITD-negativity. In contrast, 2-year OS (MLD+: 56.5%; MLD-: 65.5%) and 2-year EFS (MLD+: 13.8 months; MLD-: 16.3 months) did not differ significantly between MLD-positive/-negative patients. By univariable Cox regression analysis, gender, age, WBC count and MRC-cytogenetic risk category only were prognostically relevant for OS, while MLD was irrelevant. Therefore, CEBPAmut AML patients should be characterized only according to mut-status, cytogenetic risk groups, or additional mutations, whereas dysplasia is not relevant for this subtype.
Multilineage dysplasia does not influence prognosis in CEBPA-mutated AML, supporting the WHO proposal to classify these patients as a unique entity.
Specimen part, Disease, Disease stage
View SamplesInterest focuses on genes encoding histone demethylases in hematologic malignancies, such as EZH2 (enhancer of zeste homolog 2). EZH2 mutations were recurrently observed in lymphomas and chronic myeloid malignancies, but data in acute leukemias are limited. We investigated 13 PICALM-MLLT10 (=CALM-AF10) rearranged acute leukemia predominantly of T-lineage (7 m/6 f; 653 years) by deep-sequencing for EZH2mut and identified 3 (23%) EZH2mut carriers: one splice site mutation in exon 14, while two patients had missense mutations in the D1 region of exon 5 which interacts with different DNA methyltransferase genes (but no DNMT3Amut was detected in the 13 PICALM-MLLT10-positive patients).
EZH2 mutations and their association with PICALM-MLLT10 positive acute leukaemia.
Specimen part, Disease, Disease stage
View Samples