New targeted approaches for epigenetic age predictions.

BACKGROUND: Age-associated DNA methylation changes provide a promising biomarker for the aging process. While genome-wide DNA methylation profiles enable robust age-predictors by integration of many age-associated CG dinucleotides (CpGs), there are various alternative approaches for targeted measurements at specific CpGs that better support standardized and cost-effective high-throughput analysis. RESULTS: In this study, we utilized 4647 Illumina BeadChip profiles of blood to select CpG sites that facilitate reliable age-predictions based on pyrosequencing. We demonstrate that the precision of DNA methylation measurements can be further increased with droplet digital PCR (ddPCR). In comparison, bisulfite barcoded amplicon sequencing (BBA-seq) gave slightly lower correlation between chronological age and DNA methylation at individual CpGs, while the age-predictions were overall relatively accurate. Furthermore, BBA-seq data revealed that the correlation of methylation levels with age at neighboring CpG sites follows a bell-shaped curve, often associated with a CTCF binding site. We demonstrate that within individual BBA-seq reads the DNA methylation at neighboring CpGs is not coherently modified, but reveals a stochastic pattern. Based on this, we have developed a new approach for epigenetic age predictions based on the binary sequel of methylated and non-methylated sites in individual reads, which reflects heterogeneity in epigenetic aging within a sample. CONCLUSION: Targeted DNA methylation analysis at few age-associated CpGs by pyrosequencing, BBA-seq, and particularly ddPCR enables high precision of epigenetic age-predictions. Furthermore, we demonstrate that the stochastic evolution of age-associated DNA methylation patterns in BBA-seq data enables epigenetic clocks for individual DNA strands.

Leukocyte Counts Based on DNA Methylation at Individual Cytosines.

BACKGROUND: White blood cell counts are routinely measured with automated hematology analyzers, by flow cytometry, or by manual counting. Here, we introduce an alternative approach based on DNA methylation (DNAm) at individual CG dinucleotides (CpGs). METHODS: We identified candidate CpGs that were nonmethylated in specific leukocyte subsets. DNAm levels (ranging from 0% to 100%) were analyzed by pyrosequencing and implemented into deconvolution algorithms to determine the relative composition of leukocytes. For absolute quantification of cell numbers, samples were supplemented with a nonmethylated reference DNA. RESULTS: Conventional blood counts correlated with DNAm at individual CpGs for granulocytes (r = -0.91), lymphocytes (r = -0.91), monocytes (r = -0.74), natural killer (NK) cells (r = -0.30), T cells (r = -0.73), CD4+ T cells (r = -0.41), CD8+ T cells (r = -0.88), and B cells (r = -0.66). Combination of these DNAm measurements into the "Epi-Blood-Count" provided similar precision as conventional methods in various independent validation sets. The method was also applicable to blood samples that were stored at 4 °C for 7 days or at -20 °C for 3 months. Furthermore, absolute cell numbers could be determined in frozen blood samples upon addition of a reference DNA, and the results correlated with measurements of automated analyzers in fresh aliquots (r = 0.84). CONCLUSIONS: White blood cell counts can be reliably determined by site-specific DNAm analysis. This approach is applicable to very small blood volumes and frozen samples, and it allows for more standardized and cost-effective analysis in clinical application.

Iron Parameters Determine the Prognosis of Critically Ill Patients.

OBJECTIVE: Because iron is both an essential and toxic micronutrient influencing the development of microbial infections, we evaluated the usefulness of iron parameters as outcome predictors in ICU patients. DESIGN: Prospective clinical single-center non-interventional study. SETTING: General internal medicine ICU; German University hospital. PATIENTS: One hundred and twelve septic and 43 nonseptic ICU patients, 156 healthy blood donors. MEASUREMENTS AND MAIN RESULTS: Serum iron parameters at admission were correlated with short and long term mortality in ICU subjects. Both hepcidin and ferritin concentrations were significantly elevated in ICU patients compared with blood donors and were the highest in septic patients. On the contrary, serum iron and transferrin levels were decreased in ICU subjects with lowest values among septic patients. Hepcidin values correlated with ferritin levels, and serum iron correlated strongly with transferrin saturation. A moderate correlation of hepcidin, ferritin, and transferrin with inflammatory parameters was noted. Both short- and long-term survivors displayed higher ferritin/transferrin levels and lower transferrin saturation. In Kaplan-Meier analyses, low iron levels (cutoff 10.5 µmol/mL), low transferrin saturation (cutoff 55%), and high serum transferrin concentrations (cutoff 1.6 g/L) were associated with short- and long-term survival. In the subgroup of septic ICU subjects, low iron levels and transferrin saturation went along with a nonlethal outcome. CONCLUSIONS: Our findings demonstrate that parameters of iron metabolism, particularly transferrin saturation, that reflect serum iron availability, are strong outcome predictors in ICU patients. These data suggest that a failure of iron homeostasis with increased iron availability in serum occurs in lethally ill ICU patients and should trigger prospective clinical trials evaluating the usefulness of iron-chelating therapy in critical illness and sepsis.

Hypoxia-inducible factor 1 (HIF-1) is a new therapeutic target in JAK2V617F-positive myeloproliferative neoplasms.

Classical Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) are a heterogeneous group of hematopoietic malignancies including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The JAK2V617F mutation plays a central role in these disorders and can be found in 90% of PV and ~50-60% of ET and PMF. Hypoxia-inducible factor 1 (HIF-1) is a master transcriptional regulator of the response to decreased oxygen levels. We demonstrate the impact of pharmacological inhibition and shRNA-mediated knockdown (KD) of HIF-1α in JAK2V617F-positive cells. Inhibition of HIF-1 binding to hypoxia response elements (HREs) with echinomycin, verified by ChIP, impaired growth and survival by inducing apoptosis and cell cycle arrest in Jak2V617F-positive 32D cells, but not Jak2WT controls. Echinomycin selectively abrogated clonogenic growth of JAK2V617F cells and decreased growth, survival, and colony formation of bone marrow and peripheral blood mononuclear cells and iPS cell-derived progenitor cells from JAK2V617F-positive patients, while cells from healthy donors were unaffected. We identified HIF-1 target genes involved in the Warburg effect as a possible underlying mechanism, with increased expression of Pdk1, Glut1, and others. That was underlined by transcriptome analysis of primary patient samples. Collectively, our data show that HIF-1 is a new potential therapeutic target in JAK2V617F-positive MPN.

D variants at the RhD vestibule in the weak D type 4 and Eurasian D clusters.

BACKGROUND: One branch of the RHD phylogenetic tree is represented by the weak D type 4 cluster of alleles with F223V as the primordial amino acid substitution. F223V as well as a large number of further substitutions causing D variants are located at the extracellular RhD protein vestibule, which represents the entrance to the transmembraneous channel of the RhD protein. STUDY DESIGN AND METHODS: RHD and RHCE nucleotide sequences were determined from genomic DNA and cDNA. D epitope patterns were established with commercial monoclonal anti-D panels. RESULTS: The RHD alleles DOL-1 and DOL-2 had the two amino acid substitutions M170T (509T>C) and F223V (667T>G) in common. DOL-2 harbored the additional substitution L378V (1132C>G). Both alleles were observed in Africans and are probably evolutionary related. DMI carried M170I (510G>A), which differed from the DOL-typical substitution. DFW and DFL harbored the substitutions H166P (497A>C) and Y165C (494A>G). The antigen densities of DOL-1, DFL, and DFW were only moderately reduced. CONCLUSION: DOL-1 and DOL-2 belong to the weak D type 4 cluster of RHD alleles. Together with DMI, DFL, and DFW they represent D variants with amino acid substitutions located at extracellular loops 3 or 4 lining the RhD protein vestibule. These substitutions were of minor influence on antigen density while adjacent substitutions in the transmembraneous section caused weak D antigen expression. All these D variants were partial D and alloanti-D immunizations have been observed in DOL-1, DMI, and DFL carriers. The substitution at position 170 causes partial D although located deep in the vestibule.

Primary Osteoporosis Is Not Reflected by Disease-Specific DNA Methylation or Accelerated Epigenetic Age in Blood.

Osteoporosis is an age-related metabolic bone disease. Hence, osteoporotic patients might suffer from molecular features of accelerated aging, which is generally reflected by specific age-associated DNA methylation (DNAm) changes. In this study, we analyzed genomewide DNAm profiles of peripheral blood from patients with manifest primary osteoporosis and non-osteoporotic controls. Statistical analysis did not reveal any individual CG dinucleotides (CpG sites) with significant aberrant DNAm in osteoporosis. Subsequently, we analyzed if age-associated DNAm patterns are increased in primary osteoporosis (OP). Using three independent age-predictors we did not find any evidence for accelerated epigenetic age in blood of osteoporotic patients. Taken together, osteoporosis is not reflected by characteristic DNAm patterns of peripheral blood that might be used as biomarker for the disease. The prevalence of osteoporosis is age-associated-but it is not associated with premature epigenetic aging in peripheral blood. © 2017 American Society for Bone and Mineral Research.

Serum of myeloproliferative neoplasms stimulates hematopoietic stem and progenitor cells.

BACKGROUND: Myeloproliferative neoplasms (MPN)-such as polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF)-are typically diseases of the elderly caused by acquired somatic mutations. However, it is largely unknown how the malignant clone interferes with normal hematopoiesis. In this study, we analyzed if serum of MPN patients comprises soluble factors that impact on hematopoietic stem and progenitor cells (HPCs). METHODS: CD34+ HPCs were cultured in medium supplemented with serum samples of PV, ET, or MF patients, or healthy controls. The impact on proliferation, maintenance of immature hematopoietic surface markers, and colony forming unit (CFU) potential was systematically analyzed. In addition, we compared serum of healthy young (<25 years) and elderly donors (>50 years) to determine how normal aging impacts on the hematopoiesis-supportive function of serum. RESULTS: Serum from MF, PV and ET patients significantly increased proliferation as compared to controls. In addition, serum from MF and ET patients attenuated the loss of a primitive immunophenotype during in vitro culture. The CFU counts were significantly higher if HPCs were cultured with serum of MPN patients as compared to controls. Furthermore, serum of healthy young versus old donors did not evoke significant differences in proliferation or immunophenotype of HPCs, whereas the CFU frequency was significantly increased by serum from elderly patients. CONCLUSION: Our results indicate that serum derived from patients with MPN comprises activating feedback signals that stimulate the HPCs-and this stimulatory signal may result in a viscous circle that further accelerates development of the disease.