Introduction
Clonal hematopoiesis of indeterminate potential (CHIP) is induced by single recurrent
somatic mutations in hematopoietic stem cells (HSC) in the bone marrow, which lead
to clonal dominance . CHIP occurs frequently in an age -dependent fashion and has
emerged as a major risk factor associated with several cardiovascular disease s
(CVD)1. Sequencing studies in large cohorts revealed that CHIP driver mutations in
the genes DNMT3A, TET2, ASXL1, and JAK2 are associated with an increased risk of
heart and lung disease, stroke and increased mortality2,3,4. Importantly, the prevalence
of CHIP is 4 -fold higher in individuals with myocardial infarction 3, and the most
commonly mutated CHIP driver genes i.e. TET2 and DNMT3A, are associated with the
progression and poor prognosis of chronic heart failure 5,6. A dose-response correlation
of the size of the mutated blood cell clone with patient survival suggested a functional
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role of mutated blood cells and the progression of heart failure 6,7. The causal
involvement of CHIP-mutated blood cells was confirmed in murine models, showing
that inactivation of Tet2 in hematopoietic cells exacerbated the development of
cardiovascular diseases, such as atherosclerosis and heart failure, and also impaired
lung function in models of cigarette smoke exposure 4,8,9. Gene editing of DNMT3A in
hematopoietic stem cells additionally impaired heart function after angiotensin II
infusion 10. Because of the high prevalence and the negative impact of CHIP on human
health, there is an unmet need for effective treatment options.
Recent studies have suggested that the detrimental effects of CHIP mutations are
mediated by a pro -inflammatory activation of immune cells. Specifically, TET2 or
DNMT3A mutations increase pro-inflammatory cytokine release by myeloid cells. For
example, individuals carrying TET2 mutations present higher levels of circulating IL -8
and larger numbers of non-classical inflammatory monocytes, likely contributing to the
development of CVD 3. In line with this, atherosclerotic Tet-2 deficient mice have an
increased plaque size and higher numbers of inflammatory leukocytes, in particular,
IL-1β producing macrophages which act as potential amplifiers of disease pathology11.
Furthermore, single cell RNA sequencing of peripheral blood-derived monocytes from
individuals with heart failure or aortic valve stenosis who carry TET2 or DNMT3A
mutations exhibit increased expression of pro-inflammatory cytokines including IL-6,
IL-1β 12,13. CHIP carrying patient m onocytes also presented an augmented ge ne
signature known to promote adherence to endothelial cells as well as interactions with
T cells 13,14. The specific molecular mechanism (s) that drives pro -inflammatory gene
expression in response to mutations of the DNA methylation regulatory genes TET2 or
DNMT3A, however, is unclear.
The growing field of immunometabolism emphasizes the importance of cellular
metabolism for immune cell health and function 15-18. Recent studies have revealed
that innate immune cells such as macrophages possess distinct metabolic
characteristics that correlate with their functional state . The molecular processes that
translate such metabolic reprogramming into altered immune -associated gene
expression and effector activities are gradually coming to light. For instance, glycolysis
contributes to pro-inflammatory M1 macrophage polarization and its inhibition reduces
many facets of the inflammatory phenotype, such as phagocytosis, reactive oxygen
species ( ROS) production, and the secretion of pro -inflammatory cytokines 19.
Although metabolism has the fundamental regulatory roles in the immune cell
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activation and inflammatory response 20, cellular metabolism has not been studied in
CHIP-associated disease.
Here, we report that blood cells and ex vivo-cultured macrophages derived from heart
failure patients carrying DNMT3A CHIP mutation s show extensive alterations of
cellular metabolism. In detail, DNMT3A CHIP mutations induce the hypomethylation of
succinate dehydrogenase (SDHA) leading to the de -repression of SDHA and
consequent activation of mitochondrial activity and accumulation of the TCA cycle
metabolite malate. Mechanistically, SDHA and malate have a decisive role in the
induction of pro-inflammatory phenotype in DNMT3A deficient or mutant macrophages.
Furthermore, interfering with SDHA activity using dimethyl malonate reversed
DNMT3A mutation-induced inflammatory activation and improved cardiac function in
mice that conditionally expresses human DNMT3A cDNA carrying the R882H
mutation, one of the major mutational hotspot in clonal hematopoiesis 21. Thus, being
at the crossroads of epigenetics and immunity, metabolism and metabolic modulation
can provide a unique therapeutic opportunity for CHIP-associated diseases.
Results
DNMT3A CHIP carriers show SDHA hypomethylation and accumulation of TCA
metabolites
Given the functional role of DNMT3A in de novo DNA methylation in patients with
COPD (Chronic obstructive pulmonary disease) and cardiovascular disease 8,22,23, we
examined whether there are hypomethylated regions common to both diseases (Figure
1A and Table S1). Therefore, we assessed DNA methylation in peripheral blood cells
from heart failure and COPD patients with and without DNMT3A CHIP mutations
(Table S2) using the Infinium Human -Methylation EPIC BeadChip (850k) (WG -317,
Illumina) which covers more than 850.000 CpG sites throughout the whole genome.
Interestingly, when promoter methylation level s were ranked on the basis of β-value,
fold change and differential methylation p-value, promoter DNA methylation of none of
the inflammatory genes has been altered ( Table S3A-S3B), but the DNA methylation
of the promoter of succinate dehydrogenase complex flavoprotein subunit A ( SDHA)
was found lower in DNMT3A CHIP patients, in both disease indications (Figures 1B
and1C; Table S4). SDHA catalyzes the oxidation of succinate to fumarate and transfers
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the resulting electrons to SDHB via the electron transporting coenzyme, flavin adenine
dinucleotide (FAD) and serves as a main metabolic regulatory element in the TCA
cycle and electron transport chain (ETC) 24. To gain insight into potential
consequences of SDHA DNA methylation, we performed a metabolome analysis of
TCA cycle metabolites in the serum of heart failure and COPD patients with and without
DNMT3A mutations. As CHIP is highly correlated with aging 2, we also measured TCA
cycle metabolites in the serum of age-matched healthy donors. Importantly, several of
the TCA cycle metabolites especially isocitrate, 2-hydroxyglutarate (2HG), fumarate
and malate, were significantly increased in DNMT3A CHIP patients compared to non-
CHIP patients and healthy controls (Figure 1D). These data indicated that the DNMT3A
CHIP mutations can result in SDHA hypomethylation to impact on the TCA cycle . To
determine whether the increase in SDHA could account for elevated malate levels, we
evaluated the malate/succinate and malate/glutamate ratios, as glutaminolysis is the
other possible source of malate 25. The analysis revealed a significant increase in the
malate/succinate ratio in DNMT3A CHIP patients but not in the malate/glutamate ratio
(Figure 1E; Figure S3C). Thus, succinate to malate conversion via SDHA could be
responsible for increased malate in DNMT3A CHIP carriers with heart failure or COPD.
Together, the results demonstrate a strong association between DNMT3A CHIP
mutations and altered TCA cycle activity especially SDHA hypomethylation and
alterations in TCA cycle intermediates.
DNMT3A CHIP driver mutations augment oxygen consumption rate in
macrophages
To gain further insight into the metabolic alterations induced by DNMT3A CHIP driver
mutations, we cultured peripheral blood mononuclear cell (PBMC) -derived
macrophages from heart failure patients with and without DNMT3A CHIP mutations ex
vivo, and assessed transcriptional changes in metabolic pathways as well as
mitochondrial activity. P athway analysis from RNA-seq data revealed an enrichment
of genes associated with oxidative phosphorylation in macrophages of heart failure
patients with DNMT3A CHIP mutations (Figures 2A and 2B). Consistent with this, we
detected a higher oxygen consumption rate (OCR), a functional indicator of oxidative
phosphorylation in mitochondria, in macrophages carrying DNMT3A CHIP mutations
compared to non-CHIP macrophages. Notably, an increase in basal OCR levels and
spare capacity was observed, with no significant changes in glycolysis as assessed by
the extracellular acidification rate (ECAR) (Figures 2C and 2D). To identify the
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complexes driving the higher OCR, we analyzed the function of respiratory complexes
I–IV by assessing their contribution to oxygen consumption in permeabilized
macrophages26. This approach identified a clear impact of DNMT3A CHIP mutations
on the function of complex II ( Figure 2E). There were no consistent differences in
mitochondrial ROS production between macrophages with DNMT3A CHIP mutations
and non -CHIP macrophages (Figure S1A). However, in line with the SDHA
hypomethylation detected in CHIP DNMT3A patients, SDHA mRNA and protein levels
were clearly upregulated in DNMT3A CHIP mutation carrying macrophages from heart
failure patients (Figures 2F and 2G). Next, we confirmed previous studies showing the
increased inflammatory phenotype of macrophages, by documenting higher IL1β and
IL6 mRNA and protein levels in DNMT3A CHIP carriers versus non carriers (Figures
2H-2K). These data indicate that DNMT3A CHIP mutations in macrophages cause
DNA hypomethylation and upregulation of SDHA, leading to higher complex II activity,
that is associated with a pro-inflammatory phenotype to the macrophages.
Loss of DNMT3A in macrophages augments metabolic activity
To assess whether DNMT3A deficiency could mimic DNMT3A CHIP mutations to alter
TCA cycle activity, we silenced DNMT3A in healthy donor-derived macrophages with
stealth RNAi against DNMT3A (siDNMT3A) and a scramble negative control
(siControl) (Figure 3A;Figure S2A). DNMT3A-deficient macrophages expressed higher
levels of IL1β and IL6 mRNA and protein ( Figures 3B-3E), and demonstrated an
enhanced OCR with increased spare capacity, as an indicator of mitochondrial activity
(Figure 3F). However, ECAR was similar between DNMT3A-expressing and DNMT3A-
deficient macrophages ( Figure 3F). Similar to the macrophages carrying DNMT3A
CHIP mutations, DNMT3A-deficient macrophages demonstrated enhanced complex II
activity and an upregulation of SDHA (Figures 3G and 3H; Figure S2B). Further,
metabolomic analyses also revealed an accumulation of malate and succinate in the
supernatant of DNMT3A-deficient macrophages (Figure 3I). DNMT3A- expressing and
-deficient macrophages showed the same level of mitochondria ROS production
(Figure S2C); the same pattern was also observed between macrophages with
DNMT3A CHIP mutations and non -CHIP. As CHIP status is mostly associated with
chronic inflammation, we challenged DNMT3A deficient macrophages with LPS for 48
hours and then evaluated the mitochondria l metabolism. DNMT3A-deficient
macrophages revealed higher OCRs, spare capacity and ECAR level upon LPS
stimulation when compared with LPS-stimulated siControl macrophages (Figure S2D).
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Taken together, these results show that inactivation of DNMT3A mimicked the changes
to macrophage metabolism induced by DNMT3A CHIP mutation to increase the activity
of complex II, SDHA expression and pro-inflammatory gene expression.
SDHA/Malate axis regulates pro -inflammatory activation induced by DNMT3A
deficiency
To determine whether the pro-inflammatory response observed in DNMT3A CHIP
macrophages is a consequence of altered TCA cycle activity accounted for by the
upregulation of SDHA and accumulation of malate, we used a siRNA approach to
silence SDHA in macrophages from heart failure patients carrying DNMT3A CHIP
mutations (Figure 4A). Notably, the SDHA siRNA approach decreased both IL1β and
IL6 in macrophages from heart failure patients carrying DNMT3A CHIP mutations
(Figures 4B and 4C). Similarly, the knock down of both SDHA and DNMT3A in donor-
derived macrophages also reduced IL1β and IL6 levels (Figure 4D; E Figure S3A). The
lack of SDHA negatively impacted on the OCR, decreasing of basal respiration and
the spare capacity without affecting ECAR in DNMT3A deficient macrophages (Figure
4F). To explore the mechanisms underlying SDHA-induced pro-inflammatory
activation, we focused on malate , a downstream product of SDHA activity. Indeed,
malate accumulates in macrophages under inflammatory conditions27 and in β-glucan-
induced trained macrophages28. Interestingly, treatment of SDHA/DNMT3A deficient
macrophages with malate for 24 hours increased IL1β and IL6 levels in
SDHA/DNMT3A-deficient macrophages (Figures 4G and 4H, Figure S3B). These data
indicated that SDHA-mediated malate production contributes to the pro-inflammatory
response induced by DNMT3A deficiency.
DNMT3A deficiency induced malate production stimulates a pro-inflammatory
phenotype in a paracrine manner
Apart from the intrinsic pro -inflammatory and metabolic effects of DNMT3A in
macrophages, the paracrine functions of DNMT3A -associated macrophages on non-
mutated macrophages may contribute to the general pro-inflammatory phenotype in
patients with DNMT3A mutations , which generally carry only a relative ly small
percentage of mutant cells . To determine the paracrine activity of DNMT3A -deficient
macrophages, we applied conditional media (CM) to naïve macrophages and
evaluated the inflammatory phenotype and mitochondria activity. The CM of
siDNMT3A macrophages induced a pro-inflammatory response in naïve macrophages
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in compar ison to CM of siControl macrophages (Figures 5A and 5 B). This pro -
inflammatory phenotype is concomitant with enhancement of OCR level and
mitochondria spare capacity in naïve macrophages which are treated with CM of
siDNMT3A macrophages (Figure 5C). Interestingly, when we applied the CM of the
double knock down SDHA and DNMT3A macrophages to naïve macrophages, both
the pro-inflammatory response and mitochondria OCR are reduced (Figures 5D and
5F) which revealed a functional role of SDHA in the paracrine pro-inflammatory
activation. Given th at malate is known to elicit pro-inflammatory responses, we
determined whether the exogenous addition of malate on the macrophages could
mimic the paracrine inflammatory activation. Indeed, malate pretreatment augmented
LPS-induced expression of IL1β and IL6 mRNA (Figure 5G) also IL1β protein (Figure
5H) which concomitant with increased OCR and spare capacity (Figure 5I). Altogether,
these data show DNMT3A deficiency not only affects cell-intrinsic immunometabolic
effects but also can induce pro -inflammatory activation associated with increased
mitochondria oxygen consumption in wild type macrophages via the SDHA/malate axis
in a paracrine manner.
Inhibition of SDHA reduces inflammation and improve s cardiac function in
DNMT3A-R882H mice
We discovered that SDHA is modulated by DNMT3A CHIP mutations and in turn
serves as a major modulator of inflammation. Thus, we evaluated whether the
pharmacological inhibition of SDH via the cell-permeable molecule dimethyl malonate
29 could reverse the pro-inflammatory macrophage phenotype in DNMT3A CHIP heart
failure patients.
First, we determined the effect of dimethyl malonate on the inflammatory phenotype of
LPS-stimulated, DNMT3A CHIP macrophages from heart failure patients and observed
that dimethyl malonate treatment significantly reduced the expression of inflammatory
genes (Figure 6A; Figure S4A ). Strikingly, the effect of dimethyl malonate on IL1β
expression was much more prominent in macrophages derived from DNMT3A CHIP
heart failure patients (Figure 6B), suggesting the higher dependency of DNMT3A CHIP
macrophages on complex II activity. These in vitro findings suggest that SDHA
inhibition might be a therapeutic strategy to reduce inflammation in heart failure
patients with DNMT3A mutations.
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To assess the impact of dimethyl malonate in vivo, we used a murine model that
conditionally expresses human DNMT3A cDNA carrying the R882H mutation 21. Ly5.1
mice (C57BL/6 congenic strain that carries the differential Ptprca/CD45.1 pan
leukocyte marker) were transplanted with Mx1-Cre–:DNMT3AWT/R882H or Mx1-
Cre+:DNMT3AWT/R882H bone marrow cells before subjection to left anterior descending
artery (LAD) ligation that induces myocardial infarction (Figure 6C). 4 days a fter
induction of myocardial infarction, mice were treated daily with dimethyl malonate for
seven days ( Figure 6C). Mice transplanted with DNMT3A-mutated cells had worse
cardiac function and higher cardiac SDHA activity ( Figure 6D) than animals treated
with wild -type cells . However, dimethyl malonate improved cardiac function as
evidenced by an i mproved in arithmetic difference in ejection fraction (Figure 6E).
Interestingly, cardiac hypertrophy as measured by cardiomyocyte length (Dmaj) and
diameter (Dmin) was specifically reduced in dimethyl malonate treated mice bearing
DNMT3AWT/R882H cells (Figure 6F). Monocyte/macrophages recruitment and activation
exert the regulatory roles in cardiac remodeling and fibrosis 30. To explore the
monocyte/macrophage phenotype in mice transplanted with DNMT3A-mutated cells
followed by LAD ligation, we checked the inflammatory phenotype of bone -marrow
derived macrophages (BMDMs) . Dimethyl malonate treatment decreased the
expression of pro-inflammatory markers including Il1β and Il6 especially in mice
transplanted with DNMT3A-mutated cells followed by LAD ligation (Figure 6G). These
data manifest that the induction of DNMT3A mutation in hematopoietic cells
aggravates cardiac dysfunction after myocardial infarction. Inhibition of SDH by
dimethyl malonate reduced cardiac inflammation and improved cardiac function
specifically in mice bearing DNMT3A-mutant cells (Figure 6H).
Discussion
Probing the unexplored metabolic aspects in CHIP-associated CVD, our study shows
that mitochondrial metabolism through the oxidation of succinate following complex
II/SDHA function is one of the central hubs to shape the inflammatory phenotype of
macrophages with DNMT3A CHIP mutations or DNMT3A deficiency. Our major
findings include (i) activation of complex II in macrophages isolated from DNMT3A
CHIP mutations and DNMT3A deficient macrophages; (ii) hypomethylation and
upregulation of SDHA in DNMT3A CHIP heart failure patients; (iii) Enrichment of
malate, a downstream metabolite of SDHA, in serum from DNMT3A CHIP heart failure
patients and induces a pro -inflammatory phenotype in macrophages; (iv) genetic or
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pharmacological inhibition of SDH decreases the pro -inflammatory phenotype in
macrophages with DNMT3A CHIP mutations and DNMT3A -deficient macrophages;
and (iv) the metabolic intervention with the SDH inhibitor dimethyl malonate
ameliorated the inflammatory response and improved the cardiac function in a heart
failure animal model, which harbor myeloid-specific DNMT3A mutation.
We identified that mitochondrial metabolism majorly complex II/SDH as a key regulator
of the inflammation in CHIP associated pathology. Beyond the potential role of
mitochondrial metabolism in driving inflammatory functions, mitochondrial respiration
is required for HSC proliferation 31. Higher mitochondria respiration in DNMT3A CHIP
cells could explain why this specific CHIP mutation is the most prevalent clone in
humans32. However, longitudinal studies are warranted to confirm whether the
mitochondria metabolite fluctuations correlate with CHIP clone size.
The role of complex II/SDH in driving inflammation has previously been shown in
different pathological contexts. For example, during ischemia-reperfusion injury in the
heart and brain, reverse electron transport in complex I followed by succinate oxidation
in complex II/SDH leads to ROS production 27,33. Recently, higher activity of complex
II/SDH as a consequence of SDHA gain-of-function mutation was reported in patients
with persistent polyclonal B cell lymphocytosis 34. Similarly, our study revealed that
DNMT3A CHIP-associated heart failure also seems to be driven by complex II/SDH
hyperactivity and accompanying metabolic deregulation that was reflected in higher
OCR levels in macrophages with DNMT3A CHIP mutations as well as in DNMT3A -
deficient macrophages. Although increased mitochondrial activity is often associated
with increased ROS production, this was not observed in DNMT3A silenced
macrophages. The latter finding is consistent with findings from another group 35.
The increased SDHA in CHIP carrying heart failure patients is consistent with the
marked elevation in its downstream product, malate. In addition, our data further
suggest malate as a driver of the inflammatory phenotype and cardiac dysfunction in
heart failure patients carrying DNMT3A CHIP mutations. The accumulation of malate
during the pro -inflammatory response has been reported in macrophages 27,36 and
associated with a higher risk of arterial fibrillation and heart failure in individuals with a
high cardiovascular risk 37. Increased serum levels of malate and its potential role in
driving inflammation, may explain how a relatively low number of DNMT3A mutant cells
can support a state of chronic, low-grade inflammation in patients with DNMT3A CHIP
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mutations 32. Moreover, the malate derived from DNMT3A mutant macrophages may
also exhibit effects on the structural cells of the heart. Mechanistically, this would likely
involve malate -driven epigenetic modifications, or be me diated indirectly by
metabolites downstream of malate e.g. fumarate and 2HG, that also act as epigenetic
modifiers 38,39.
DNMT3A catalyzes the de novo methylation of cytosine residues in DNA. Previously,
we 8 and others 23 reported DNA hypomethylation in blood samples of COPD and CVD
patients with DNMT3A CHIP mutations. Fitting with this, our analyses indicate that
SDHA was also upregulated in macrophages carrying DNMT3A CHIP mutations. This
observation implies a clear link between SDHA DNA methylation and the
transcriptional regulation of SDHA. While it is clear that DNMT3A exerts a number of
different functions during inflammation, e.g. the type I IFN response 35 and antiviral
innate immunity 40, our data point to a critical role of DNMT3A -dependent changes in
DNA methylation in the control of immune cell metabolism.
Importantly, based on the immunometabolic characteristics of patients with DNMT3A
mutation, metabolic modulation might provide a potential therapeutic approach. In
corroboration, intravenous infusion of SDH inhibitor – dimethyl malonate, in a mouse
model that mimics DNMT3A -mutated CHIP that has been subjected to myocardial
infarction demonstrated a significant improvement of cardiac function, and reduction of
cardiac inflammation. Although dimethyl malonate is not tested in any clinical trials, the
natural SDHA inhibiting compounds with reduced toxicity such as itaconate and its
derivatives 41 can be considered as promising approaches for future clinical trials.
Alternatively, targeting inflammation with antibodies directed against IL-1β and IL-6, or
NLRP3 or STAT-3 inhibitors may mitigate the effects of CHIP, both by reducing clonal
expansion and CHIP -dependent inflammation. Certainly, IL -1β neutralization in the
Canankinumab Anti -inflammatory Thrombosis Outcomes (CANTOS) trial suggested
that TET2 variants may respond better to canakinumab than those without CHIP 42. An
added advantage of metabolic modulation includes manipulation of the signaling
pathways that are necessary and upstream of the inflammatory response.
In conclusion, our findings revealed SDHA as a disease modifier in DNMT3A CHIP
heart failure , driving malate accumulation and inflammatory reprogramming of
macrophages. This study reports for the first time how the metabolic regulatory
functions can be involved in DNMT3A CHIP pro-inflammatory and cardiac phenotypes
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which can be used as a promising individualized therapeutic approach in CVD patients
with DNMT3A CHIP mutations.
Acknowledgments
We would like to acknowledge excellent technical contributions of Laura Kahnke and
Katharina Leib. Funding: This study was funded by the DFG SFB -1213 (Project A01,
A05 grants to SSP, A10N grant to RS) and ERC Consolidator Grant (866051 to SSP).
RS, SD, SSP are supported by Excellence Cluster CPI (Exc2026).
Author Contributions
SM, RS, SD, SSP designed the research study. SM, IH, GZ, SK, XL, MS, SG, MP
conducted the experiments and acquired the data. SM, SK, CMT, MS, MR, IF, RJR,
ML, RS, SD, SSP analyzed the data. FB, MHS, ML provided bioinformatic support. SC,
KK, SK, CFV, RB, AZ, WS provided clinical samples and CHIP mutational status. SM,
RS, SD, SSP took the lead in writing the manuscript. IF, AZ and WS provided critical
feedback and helped shape the research, analysis and manuscript.
Declaration of Interests
The authors declare no competing interests.
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Figure titles and legends:
Figure 1. DNA methylation and metabolic profile of CHIP patients with DNMT3A mutations. (A) Schematic representation of the
design of DNA methylation and TCA metabolomics analysis using blood and serum, respectively, from Non-CHIP and DNMT3A CHIP
patients. (B) MA-plot for mean non-CHIP DNA methylation level against log2 (mean.methylation.DNMT3A/mean.methylation.Non-CHIP)
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between DNMT3A CHIP (heart failure ( HF), n=5; COPD, n=16) and non-CHIP (HF, n=3; COPD, n=1 0) patients. Top differentially
hypomethylated genes according to mean CpG methylation in their promoter region with p<0.01 and fold change ≥0.2 are shown in blue.
(C) Methylation level of three CG sites cg20741528, cg04125223 and cg23490161 which are located in the SDHA promoter between
patients with DNMT3A CHIP (HF, n=5; COPD, n=1 6) and non-CHIP (HF, n=3; COPD, n=10 ) patients. (D) The percentage of serum
abundance of TCA metabolites in DNMT3A CHIP (HF, n=8; COPD, n=15) compared with non-CHIP (HF, n=10; COPD, n=22) patients
and healthy donors (n=24). (E) Ratio of the percentage of malate over succinate and glutamate in patients with DNMT3A CHIP mutation
(HF, n=8; COPD, n=15) in compared with non-CHIP associated patients (HF, n=10; COPD, n=22) and healthy donors (n=24). Statistical
significance was assessed by two-tailed unpaired Student’s t-test and one-way ANOVA Tukey’s multiple comparison test. *p <0.05, **p
<0.01, ***p< 0.001, ****p< 0.0001.
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Figure 2. Human DNMT3A CHIP macrophages display a distinct mitochondria l metabolism with the pro -inflammatory
phenotype. (A) RNA sequencing was performed on PBMC-derived macrophages isolated from HF patients with DNMT3A CHIP (n=2)
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and non-CHIP (n=2) mutation. Top listed pathways with higher normalized enriched scores from the differentially expressed genes from
RNA sequencing. (B) Gene set enrichment analysis of oxidative phosphorylation genes in PBMC-derived macrophages of HF patients
with DNMT3A CHIP (n=2) and non-CHIP (n=2) mutations. (C) Oxygen consumption rate ( OCR) measurement of PBMC -derived
macrophages of HF patients with DNMT3A CHIP (n=3) and non-CHIP (n=3) mutations. Data are shown as OCR graphs (left) and (D)
followed by bar graphs of basal respiration, spare capacity and extracellular acidification rate (ECAR) (right). (E) OCR measurements
of permeabilized PBMC-derived macrophages of HF patients with DNMT3A CHIP (n=3) and non-CHIP Macrophages (n=3) mutations
before and after the addition of substrate and associated -complex specific inhibitors, as indicated (dashed lines). Data are shown as
OCR graphs (left) and bar graphs of specific com plex OCRs (right). (F) mRNA expression of SDHA in PBMC-derived macrophages of
HF patients with DNMT3A CHIP (n=3) and non-CHIP (n=3) mutations. (G) SDHA protein level followed by the densitometric
quantification of relative SDHA expression in PBMC-derived macrophages of HF patients with DNMT3A CHIP (n=3) and non-CHIP (n=3)
mutations. (H) mRNA expression of IL1β (n=3) followed by (I) protein level of pro -IL1β (n=2) in PBMC-derived macrophages of HF
patients with DNMT3A CHIP and n on-CHIP mutations. (J, K) mRNA expression of IL6 and secretary levels of IL6 in PBMC-derived
macrophages of HF patients with DNMT3A CHIP (n=3) and non-CHIP (n=3) mutations (n = 3). Statistical significance was assessed by
a two-tailed unpaired Student’s t-test. *p <0.05, **p <0.01, ***p< 0.001
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Figure 3. Loss of DNMT3A in macrophages renders a pro-inflammatory and distinct mitochondria metabolism phenotype. (A)
Protein level of DNMT3A in human PBMC-derived macrophages treated with stealth RNAi against DNMT3A (siDNMT3A) and a scramble
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negative control (siControl) (n = 3). (B) mRNA expression of IL1β and (C) protein level of pro-IL1β in DNMT3A deficient PBMC-derived
macrophages followed by the densitometric quantification of relative IL1β expression (n = 3). (D) mRNA expression of IL6 and (E)
secretory level of IL6 protein of DNMT3A deficient PBMC-derived macrophages ( n = 3). (F) OCR measurement of DNMT3A deficient
human PBMC-derived macrophages (n = 3). Data are shown as OCR graphs (left) representative of three independent experiments and
summary bar graphs of spare capacity also extracellular acidity rate (ECAR) (right). (G) OCR measurements of permeabilized DNMT3A
deficient human PBMC -derived macrophages ( n = 3) before and after the addition of substrate and associated -complex specific
inhibitors, as indicated (dashed lines). Data are shown as OCR graphs (left) representative of three independent experiments, and
summary bar graphs of complex II specific OCR s (right). (H) mRNA expression of SDHA in DNMT3A deficient PBMC -derived
macrophages (n = 3). (I) Abundance of 2HG, malate and succinate metabolites in supernatant of DNMT3A deficient human PBMC-
derived macrophages (n = 3). Statistical significance was assessed by a two -tailed unpaired Student’s t-test and. *p <0.05, **p <0.01,
***p< 0.001.
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Figure 4. SDHA/Malate axis regulates pro-inflammatory and metabolic profile in macrophages. (A, B) mRNA expression of SDHA,
IL1β and IL6 and in PBMC-derived macrophages from HF patients with DNMT3A CHIP mutations after transfection with siControl and
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siSDHA for 48 hours (n=3). (C) SDHA and pro-IL1β protein level in PBMC-derived macrophages from HF patients with DNMT3A CHIP
mutations after transfection with siControl and siSDHA for 48 hours (n=2) . (D) IL1β and IL6 mRNA level in DKD SDHA and DNMT3A
PBMC-derived human macrophages (n=3). (E) Pro-IL1β protein followed by the densitometric quantification of relative pro-IL1β protein
expression in double knock down (DKD) SDHA and DNMT3A PBMC-derived human macrophages (n=3). (F) OCR measurement in
DKD SDHA and DNMT3A PBMC-derived macrophages (n=3). Data are shown as OCR graphs (left) representative of three independent
experiments and summary bar graphs of basal respiration, spare capacity and ECAR (right) (n=3). (G) IL1β and IL6 mRNA level in DKD
SDHA and DNMT3A PBMC-derived human macrophages followed by malate (5mM) treatment for further 24 hours (n=3). (H) Pro-IL1β
protein in DKD SDHA and DNMT3A PBMC-derived human macrophages followed by malate 5mM treatment for further 24 hours (n=2).
Statistical significance was assessed by a two-tailed unpaired Student’s t-test and. *p <0.05, **p <0.01, ***p< 0.001.
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Figure 5. DNMT3A CHIP macrophages induces pro-inflammatory phenotype in paracrine manner. (A) mRNA level of inflammatory
cytokines, IL1β and IL6 in PBMC-derived macrophages from healthy donors that were subjected to CM of siDNMT3A and siControl
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macrophages for 72 hours (n=3) (B) Pro-IL1β protein in PBMC-derived macrophages from healthy donors that were subjected to CM of
siDNMT3A and siControl macrophages for 72 hours (n=2). (C) OCR measurements of human PBMC-derived macrophages (n = 3) which
are treated with CM of siDNMT3A and siControl macrophages for 48hrs hours. Data are shown as OCR graphs (left) representative of
three independent experiments, and summary bar graphs of basal OCR and spare capacity (right). ( D-E) mRNA level of inflammatory
cytokines, IL1β, IL6 (n=3) and pro-IL1β protein (n=2) in PBMC-derived macrophages from healthy donors that were subjected to CM of
DKD of siSDHA and siDNMT3A macrophages for 72 hours, respectively (F) OCR measurements of human PBMC-derived macrophages
(n = 3) which are treated with CM of DKD of siSDHA and siDNMT3A macrophages for 48hrs hours. Data are shown as OCR graphs
(left) representative of three independent experiments, and summary bar graphs of basal OCR and spare capacity (right). (G-H) mRNA
level of inflammatory cytokines, IL1β, IL6 and pro-IL1β protein in PBMC -derived macrophages from healthy donors which were
pretreated with malate (5mM) for 3 hours followed by LPS stimulation (100ng/ml) for further 48 hours (n=3). (I) OCR measurements of
human PBMC-derived macrophages ( n = 3) which are pretreated with malate (5mM) for 3 hours followed stimulation with LPS for 48
hours. Data are shown as summary bar graphs of basal OCR and spare capacity (n=3). Statistical significance was assessed by two-
tailed paired Student’s t-test and one-way ANOVA Tukey’s multiple comparison test. *p <0.05, **p <0.01, ****p< 0.0001.
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Figure 6. Inhibition of SDHA with dimethyl malonate improves cardiac function
and reduces pro -inflammatory phenotype after myocardial infarction in
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DNMT3A-R882H mice. (A) mRNA level of inflammatory cytokines, IL1β, IL6 and
SDHA in PBMC-derived macrophages from CHIP HF patients with DNMT3A mutations
which were pretreated with dimethyl malonate (10mM) for 3 hours followed by LPS
stimulation (100ng/ml) for further 48 hours (n=3). (B) Fold change of IL1β mRNA levels
between PBMC-derived macrophages from HF patients with DNMT3A mutations and
non-CHIP after dimethyl malonate treatment (10mM) under LPS stimulation (100ng/ml)
for 48 hours (n=3). (C) Schematic representation of ligation of the left anterior
descending artery (LAD) in humanized DNMT3A-R882H (D3a) mouse following with
dimethyl malonate treatment. (D) in situ SDHA activity in heart of transplanted mice
with DNMT3A-mutated and WT HSCs followed by quantification analysis with Image
J. (E) Arithmetic difference, as cardiac function indicator , in D3a mice and WT upon
LAD followed by dimethyl malonate treatment. (F) Cardiac hypertrophy phenotype
which is indicated with cardiomyocyte length (Dmaj) and diameter (Dmin) in D3a mice
and WT upon LAD followed by dimethyl malonate treatment. (G) mRNA expression of
pro-inflammatory markers including Il1β and Il6 of bone-marrow-derived macrophages
(BMDMs) from WT and D3a mice upon ligation of LAD followed by dimethyl malonate
treatment.(H) DNMT3A mutations in CHIP macrophages leads to hypomethylation of
SDHA gene which results in higher gene expression and protein level of SDHA also
enhancement activity of complex II in ETC. SDHA/complexII converts succinate to
fumarate followed by higher malate production in DNMT3A CHIP macrophages.
Malate can augment the pro-inflmmatory response in patients with DNMT3A mutations
which finally can lead to HF in this group of patients. Statistical significance was
assessed by a two -tailed unpaired Student’s t-test and one-way ANOVA Tukey’s
multiple comparison test. *p <0.05, **p <0.01, ***p< 0.001, ****p< 0.0001.
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STAR Methods
Study population
For COPD patients, we used the COSYCONET as a German multicenter prospective
observational trial, which recruited 2741 patients aged 40 years and older with
diagnosis of COPD between 2010 and 2013 in 31 study centers. COSYCONET was
approved by the ethics c ommittees at all participating sites, and all participants
provided written consent. The study is registered at ClinicalTrials.gov (NCT01245933).
The Study protocol V1.6 from the 23.05.2011 states full compliance with national laws,
ICH Guideline for Good Clinical Practice (GCP) E6 from June 1996 and the declaration
of Helsinki. The study subjects of COSYCONET gave written consent upon study
inclusion for genetic analysis of blood samples. Participants also gave written consent,
that results genetic analysis would not be reported to them. All blood samples for CHIP
sequencing were drawn at visit 1 (between 2011 and 2013). We estimate the risk of
malignancy with 0.5-1% per year in CHIP positive patients. DNA sequencing and data
analysis took place 6-8 years after sampling, the study team considered this no longer
relevant for the patient’s safety. For HF patients, and healthy controls, whole blood
samples were taken at outpatient clinic visits patients and sequenced for the presence
of DNMT3A CHIP-driver mutations. Sequencing was done as described previously 43.
In total, blood samples of 11 patients with heart failure and DNMT3A driver mutations
and 13 patients with heart failure without CH mutations were used for this study. In
addition, six patients without heart failure were used as controls. The obtaining of the
blood samples was in the frame of the UCT -Project-Nr.: KardioBMB#2022-001 with
Title: ‘Epigenetic and metabolic contribution to inflammatory phenotypes of CHIP´ and
KardioBMB#2020-004: ‘Clonal hematopoiesis in heart failure patients; Amendment 1:
Metabolic status and the connection with DNMT3A CHIP in patients with HFrEF´.
Informed consent was obtained from all patients. The study was approved by an
institutional review committee of the University Hospital of the Johann Wolfgang
Goethe University in compliance with internal standards of the German government,
and procedures followed were in accordance with institutional guidelines and the
Declaration of Helsinki
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26
DNA methylation analysis
DNA was isolated from the EDTA blood samples obtained from the patients using the
QIAamp DNA mini Kit (Qiagen), according to the manufactures protocol. Qubit dsDNA
HS Assay kit was used to measure the DNA concentration (Q32851, Invitrogen). For
DNA methylation analysis, we applied 200 –500 ng of DNA as input. The Infinium
Human-Methylation EPIC BeadChip (850k) (WG-317, Illumina) was used to determine
the DNA methylation status of more than 850.000 CpG sites, respectively following the
producer’s guidelines (1). On -chip quality metrics of all samples were carefully
controlled. The RnBeads software (version 2.0) was used for analysis of the DNA
methylation arrays 44.
Raw intensities derived from IDAT files passed quality control on probes and samples.
RNbeads was run on the IDAT files to remove sex c hromosomes and SNPs to avoid
confounding factors. We used the following commands for this as part of the
rnb.options function: min.group.size=1, differential.enrichment = TRUE,
import.table.separator = ",", normalization = NULL, normalization.method = "illumina",
normalization.background.method = "methylumi.noob", filtering.snp = "yes",
filtering.sex.chromosomes.removal = TRUE, filtering.missing.value.quantile = 0,
exploratory.columns = SampleID, differential.comparison.columns =GroupID,
differential.comparison.columns.all.pairwise = GroupID. We used the differential
methylation analysis capabilities to contrast samples with and without observed CHIP
mutation for 26 COPD patients and 8 patients with CHF. Individual site -based
methylation levels were calculated and subsequently used for region -based
methylation level assessment in promoters of genes, by considering the mea n
methylation of all CpG sites on the array that belonged to the gene promoter.
We used an MA-plot to illustrate the differences in promoter methylation between
CHIP and no CHIP patients using a differential methylation p-value cutoff of 0.01 and
methylation fold change of at least 0.2 to remove genes with marginal differences.
We highlighted the top 10 genes with the strongest DNA methylation differences.
Sample Preparation for NGS and High-Throughput Sequencing
Before sequencing, the pooled libraries we re diluted and denatured according to the
NextSeq System Denature and Dilute Libraries Guide (Illumina) and 1% PhiX DNA
was added. The pooled libraries were sequenced on a NextSeq 500 sequencer
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(Illumina) using the NextSeq 500/550 Mid Output, version 2 kit (300 cycles) according
to the manufacturer’s instructions. Briefly, the sequencer was operated in a paired-end
sequencing mode with 2 × 150 bp read length and 2 × 8 bp index read length. The BCL
files were demultiplexed and converted to FASTQ files using the FASTQ Generation
tool on BaseSpace (Illumina). The median coverage across all BMC samples was
4282× before UMI family clustering and 630× with inclusion of UMIs.
Variant Calling and Annotation Strategies: Read quality was assessed using FastQC.
FASTQ f iles from each patient were merged and reads were grouped into unique
molecular identifier (UMI) families using the UMI -tools software package 45. Reads
were mapped to the hg19 draft of the human genome using Burrows -Wheeler
Alignment–MEM 46. The `dedup` command of the U MI-tools software package was
used to remove polymerase chain reaction duplicates with the same UMIs and
alignment coordinates. Variant calling was performed using FreeBayes without allele
frequency threshold, a minimum alternate read count of 2, and a min imum base and
mapping quality of 20. Variant effect prediction and variant annotation was performed
using SnpEff and SnpSift (2,3,4).
The identified variants were processed and filtered using the R programming language,
version 3.3.1 (R Programming). Commo n single -nucleotide polymorphisms with a
minor allele frequency of at least 5% in either the 1000 Genome Project, Exome Variant
Server, or ExAC databases were excluded 47. In addition, variants with a low mapping
quality (<20) and variants occurring in 8% or more of the patients in the studied cohort
were considered as technical artifacts and excluded. Furthermore, variants covered
with fewer than 100 reads in at least 1 set of amplicons (CAT A or CAT B), variants
called with only 1 of the set of amplicons (CAT A or CAT B), single -nucleotide
polymorphisms identified as common in the single-nucleotide polymorphism database
(≥1% in the human population), and variants with sequence ontology terms “LOW” or
“MODIFIER” were filtered out. According to previously established definitions, all
variants with a variant allele fraction (VAF) of at least 0.02 (2%) were considered; VAF
was calculated by using the formula VAF = alternate reads / (reference + alternate
reads). Variants with a VAF of 0.45 to 0.55 were not considered to exclude potential
germline variants. The variants were further validated on the basis of being reported in
the literature and/or the Catalogue of Somatic Mutations in Cancer 48 and ClinVar 49 .
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Metabolomic and cytokine analysis
Plasma samples were isolated at study visits in the according study center. For
Isolation and direct processing of samples the studies (SOP) was followed. Blood vials
were centrifuged and frozen within 1h after sampling. A temperature log protocol was
followed. All biomaterials were stored in the central biobank. The transfer of the
samples from the study centers to the central biobank and all related procedures are
defined by SOPs. The transportation system is established, and every step described
in the c orresponding SOP. The samples are transported under dry ice pellets. After
receipt at the biobank the samples are inspected immediately, imported in the
database and stored at -80°C until further processing.
Plasma samples were extracted in ice-cold 85% methanol (10 µL/µL), shortly vortexed
and lysed with one freeze -thaw cycle. The homogenate was centrifuged (15,000 g, 5
minutes, 4 °C). The supernatant was collected and the samples were evaporated to
dryness in a Concentrator Plus (Eppendorf, Wesseling-Berzdorf, Germany). Samples
were reconstituted in 50 µL water + 0.5% formic acid, transferred to autosampler vials
and subsequently analyzed via liquid chromatography coupled to tandem mass
spectrometry (LC-MS/MS). Negative ionization ESI -LC MS/MS was perform ed on an
Agilent 1290 Infinity LC system (Agilent, Waldbronn, Germany) coupled to a
QTrap 5500 mass spectrometer (Sciex, Darmstadt, Germany). Ion source parameters
were as follows: CUR 30 psi, CAD medium, Ion Spray Voltage - 4500 V, TEM 400 °C,
GS1 45 psi, GS2 25 psi. TCA metabolites were identified with authentic standards
and/or via retention time, elution order from the column and 1 -2 transitions. For
quantification, specific MRM transitions for every compound were normalized to its
appropriate standards in a standard curve. Reversed -phase LC separation was
performed by using a Waters Acquity UPLC HSS T3 column (150 mm × 2.1 mm, 1.8
µm). Compounds were eluted with a flow rate of 0.4 ml/min and with the following 10
min gradient: 2% B for 1.5 min, a 3 min gradient to 100% B, a cleaning and equilibration
step. Solvent A consisted of 100 % water containing 0.5 % formic acid and solvent B
consisted of 100 % methanol containing 0.5 % formic acid. Column oven temperature
was set to 40 °C, and the autosampler was set to 6 °C. Injection volume was 2.5 µL.
Macrophage supernatant IL6 was measured by human IL6 Quantikine ELISA Kit
(R&D) based on manufacture’s instruction.
Generation of human and mouse macrophages and cell culture
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29
Human and mouse macrophages were generated from peripheral blood mononuclear
cells (PBMCs) and bone marrow (BM) cells, respectively as previously described.
Briefly, healthy donors, CHIP and non-CHIP PBMCs isolated from buffy coats obtained
from the blood bank of the Universities of Giessen an d Marburg Lung Center and
Frankfurt Universities Hospital using Ficoll density gradient centrifugation. Platelets
and red blood cells (RBC) were removed by two washing steps with RBC lysis buffer
(BD Biosciences) and phosphate-buffered saline (PBS), respectively. The pellets were
passed through the filter and then resuspended in ice cold Miltenyi buffer followed by
adding magnetic-activated cell sorting (MACS) CD14 beads (Miltenyi Biotec) and
incubation at 4°C which terminated by adding Miltenyi buffer afte r 15 minutes. The
tubes were centrifuged at 300 x g for 5 minutes at room temperature. The supernatant
was removed and the pellets were resuspended in ice cold Miltenyi buffer. The positive
CD14 selection was performed by using LS 2 (Miltenyi Biotec) colum ns were already
equilibrated by adding Miltenyi buffer. The cell solution was applied onto the columns
and then washed three times with Miltenyi buffer. After the last wash, the columns were
filled with Miltenyi buffer and then plunged to flushing out the CD14-positive cells which
were collected with centrifugation at 300 g for 5 minutes with acceleration. The
supernatant was discarded and the cell pellet was resuspended in RPMI-1640 (20 ml)
(Gibco) supplemented with 10% (v/v) fetal -bovine serum (FBS; Life technology) and
penicillin-streptomycin (Pen/Strep; Gibco). The cells were counted and plated at 0.5 x
106 cells/ml in the media plus macrophage colony-stimulating factor (M-CSF,25 ng/ml,
R&D Systems). Cells were maintained at 37°C, 5% CO 2 for 5 days, to allow
differentiation into macrophages with one media change in 3 rd day. Thereafter,
macrophages were transfected with stealth RNAi siRNAs against DNMT3A
(HSS176225, Thermofisher) and siRNA against SDHA (Catalog no.: SI00060445,
Qiagen) and a scramble negative control (AllStars Neg. siRNA, Catalog no.: 1027292,
Qiagen) using the HiPerFect Transfection Reagent (Qiagen) in an optimum serum-free
medium based on the manufacturer’s protocol.
Regarding mouse macrophages, the tibia and femur from m ice were dissected, and
each bone was subsequently flushed with 15 ml of RPMI 1640 medium with 1%
Pen/Strep. The cells went through a 40 -μM cell strainer, centrifuged, and then
resuspended in RPMI 1640 medium which contained 10% FCS, 1% Pen/Strep, and
mouse M -CSF(20 ng/ml; Roche) and plated on a six -well plate. We changed the
medium on alternate days with RPMI 1640 medium contained 10% FCS, 1%
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30
Pen/Strep, and mouse M -CSF (20 ng/ml) until undifferentiated macrophages were
obtained. For polarization of human a nd mouse macrophages toward the pro -
inflammatory macrophage, we stimulated them with LPS (100 ng/ml) for 48 hours.
RNA isolation, complementary DNA synthesis, and quantitative PCR
Total RNA was extracted with RNeasy Mini Kit (Qiagen, Hilden, Germany). Then , we
was transcribed RNA into complementary DNA (cDNA) using the high-capacity cDNA
reverse transcription Kit (Applied Biosystems, Waltham, USA) according to the
manufacturer’s instructions. Also, quantitative PCR (qPCR) was performed using
SYBR Green PCR Master mix and the StepOne real -time PCR System (Applied
Biosystems, Waltham, USA) at the following conditions: 10 min at 95°C, followed by
40 cycles of 30s at 95°C, 30s at 58° to 60°C. Analysis was done using the StepOne
plus software and GraphPad Prism. Expression was determined using the Δ ΔCT
Method
followed by fold change calculation. CT -values were normalized to the
housekeeping gene -encoding hypoxanthine -guanine phosphoribosyl transferase
(HPRT1) using the equation ΔCT = CT reference – CTtarget. The primer sequences were
designed using sequence information obtained from the National Center for
Biotechnology Information database and purchased from Sigma -Aldrich and shown
table S1.
Western Blotting
The cells w ere lysed in RIPA lysis buffer containing pr otease and phosphatase
inhibitors followed by clearing step through high -speed centrifugation. Proteins were
separated using 10% polyacrylamide gels and transferred to polyvinylidene difluoride
membranes. Following the blocking with 5% bovine serum albumin , the membranes
were incubated with a primary antibody overnight at 4°C. After washing with tris -
buffered saline containing Tween 20 (TBST) for 3 times, the blots were incubated with
secondary antibodies coupled with horse radish peroxidase diluted in 5% m ilk
dissolved in TBST buffer. The protein -antibody conjugates were detected using an
enhanced chemiluminescence detection system. Protein expression was quantified
using band intensity values (in arbitrary units) that were normalized to β -actin (ACTB)
by ImageJ software. The Western blots shown in the figure are representative of 3
independent experiments unless it mentioned in the figure legends. Antibody details
were shown in table S2.
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31
Metabolic flux analysis
We used A Seahorse XFe96 extracellular flux analyzer (Seahorse Bioscience, Agilent
Technologies) to measure OCRs and ECARs. Mitochondrial perturbation experiments
were carried out by sequential addition of 1.5 μM oligomycin (Agilent Technologies),
1 μM FCCP (carbonyl cyanide 4 -(trifluoromethoxy) pheny lhydrazone; Agilent
Technologies) and 0.5 μM rotenone/antimycine (Agilent Technologies). For monitoring
the OCR of intact mitochondria, CD14 -MACS sorted monocytes were seeded in 96
wells Seahorse plate in 15*10 4 cells/per well and differentiated to macrophages in
RPMI-1640 media (Gibco) which contained with 10% (v/v) FBS (Life technology), 1%
Pen/Strep plus M-CSF(25 ng/ml, R&D Systems) for 5 days with one media change in
3rd day. Thereafter, the media was removed and replaced by MAS buffer (70 mM
sucrose, 220 mM mannitol, 10 mM KH 2PO4, 5 mM MgCl 2, 2 mM HEPES and 1 mM
EGTA), then macrophages treated with saponin (25 μg/ml) as membrane
permeabilizer (Sigma -Aldrich), which was followed by addition of 5 mM pyruvate,
2.5 mM malate, 1 mM ADP and 1 μM roteno ne for monitoring complex I -driven
respiration; 10 mM succinate, 1 mM ADP and 0.04 mM malonate for monitoring
complex II-driven respiration; 0.5 mM duroquinol, 1 mM ADP and 0.02 mM antimycin A
for monitoring complex III -driven respiration; 0.5 mM TMPD, 2 m M ascorbate, 1 mM
ADP and 20 mM sodium azide (all from Sigma -Aldrich) for monitoring complex IV -
driven respiration. OCR changes upon the substrate addition were calculated relative
to the preinjection rate.
SDH enzyme activity
For tissue section preparation, heart tissues were harvested, snap -frozen and stored
at −80°C. The tissue blocks which were embedded in O.C.T. compound cut in 6 μm
thickness at slow and constant speed and placed up on Superforst microscopy slides.
Slides were stored at −80°C for further enzyme activity staining procedure. SDH
enzyme activity staining on tissue sections were carried out as described by Miller et.
al 50. Briefly, we used 0.1 M Tris-HCl buffer pH 8.0 for SDH activity. In the SDH-specific
buffer, 10% polyvinyl alcohol was dissolved at 60 °C under stirring until the mixture
was clear. Then, SDH-specific assay media were prepared by adding 60mM succinate,
5mM sodium azide, 0.2 mM phenazine and 5 mM nitroblue tetrazolium chloride (NBT)
including negative control reactions with the addition 250 mM malonic acid (for SDH
inhibition). Assay medium containing the enzyme -specific substrates was applied to
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32
cover the whole tissue section slide. Enzyme reactions were carried out at RT for
around 15 min or until high staining was visible and stopped by the removal of the
incubation medium and washed with warm PBS.
MitoSOX ROS staining
Reactive oxygen species (ROS) formation in macrophages with DNMT3A CHIP
mutations and non -CHIP was determined using the MitSOX™ red mitochondrial
superoxide indicator (Invitrogen, Waltham, USA) according to the manufacturer’s
instructions. PBMC -derived macrophages were grown on cover slips as explained
before and treated with 5 µM MitoSOX reagent working solution for 10 min at 37 °C.
Then after, the coverslips were washed three times with warm 1x PBS, and imaged
using a fluorescence microscope (Keyence, Osaka, Japan).
RNAseq analysis
Trimmomatic version 0.39 was employed to trim reads after a quality drop below a
mean of Q20 in a window of 20 nucleotides and keeping only filtered reads longer than
15 nucleotides 51. Reads were aligned versus Ensembl human genome version hg38
(Ensembl release 104) wit h STAR 2.7.10a 52. Aligned reads were filtered to remove:
duplicates with Picard 2.27.4 (Picard: A set of tools (in Java) for working with next
generation sequencing data in the BAM format), multi -mapping, ribosomal, or
mitochondrial reads. Gene counts were established with featureCounts 2.0.3 by
aggregating reads overlapping exons on the correct strand excluding those
overlapping multiple genes 53. The raw count matrix was normalized with DESeq2
version 1.36.0 54. Contrasts were created with DESeq2 based on the raw count matrix.
Genes were classified as significantly differentially expressed at average count > 5,
multiple testing adjusted p-value < 0.05, and -0.585 0.585. Ensembl gene
annotation was enriched with UniProt data (Activities at the Universal Protein Resource
(UniProt)).
Downstream analyses
All downstream analyses are based on the normalized gene count matrix.Volcano and
MA plots were produced to highlight DEG expression. A global clustering heatmap of
samples was created based on the euclidean distance of regularized log transformed
gene counts. Dimension reduction analyses (PCA) were performed on regularized log
transformed counts using the R packages FactoMineR 55. DEGs were submitted to
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33
gene set overrepresentation analyses with KOBAS 56. The resulting bubble plot shows
pathways with Benjamini-Hochberg corrected p-value < 0.05 (represented by dashed
line). The larg er gray circles are scaled to the number of genes comprising the
respective pathway, while the smaller colored circles represent subsets found to be
DEGs.
Animal model and heart functional parameters
Mx-Cre+/Dnmt3a (Ly5.2) and Mx -Cre-Dnmt3a (Ly5.2) have been previously
described21. B6.SJL (Ly5.1) mice were obtained from The Jackson Laboratory.
Animals were housed under s tandard laboratory conditions. Age matched Mx -
Cre+/Dnmt3a and Mx -Cre-/Dnmt3a donor mice (Ly5.2) were treated with pI:pC
(400μg/mouse intraperitoneally [i.p.]) for 3 nonconsecutive days (Amersham). Donor
bone marrow cells (2x106 cells) were intravenously in jected into lethally irradiated
(7.5Gy total body irradiation) B6.SJL recipients (Ly5.1). Recipient mice were
maintained on antibiotic-containing drinking water (ciprofloxacin 50 mg/kg) 5 days pre
lethally irradiation and 2 weeks post irradiation and trans plantation. Peripheral blood
engraftment was assessed by flow cytometry 6 weeks after reconstitution.
Left anterior descending artery (LAD) ligation in mice
Six weeks after reconstitution myocardial infarction was induced by permanent ligation
of the left anterior descending artery in female mice as described previously57. In brief,
anaesthesia was induced with isoflurane (4%/800 ml O2/min) and maintained by
endotracheal ventilation (2 –3%/800 ml O2/min). Thoracotomy was performed in the
fourth left intercostal space. The left ventricle was exposed, and the left coronary artery
was permanently occluded. Chest and skin were closed, and anesthesia was
terminated. Animals were extubated when breathing was restored. Initial myocardial
injury was evaluated by measuring cardiac troponin T level s in plasma 24 h after
induction of myocardial infarction.
Echocardiographic measurements
Cardiac function in mice was investigated non-invasively on a VisualSonics Vevo2100.
Echocardiographic measurements were performed without anesthesia. Systolic
function was evaluated in the M -mode parasternal short -axis, B -mode parasternal
long- and short-axis view. The investigator was blinded towards the study group.
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34
Histopathological analysis
For paraffin sections, heart tissue was rinsed in PBS, fixed in 10% buffered formalin at
4°C, dehydrated, paraffinized and sectioned on a microtome (Leitz, 5µm). Tissue
sections were then stained with Hematoxylin and Eosin (MilliporeSigma) and Masson
Trichrome (MilliporeSigma) according to the manufacturer’s instructions. ImageJ
software (NIH) was used to quantify the cardiomyocyte diameter, minor cell diameter
(Dmin, µm) and major cell diameter (Dmaj, µm). Criteria for myocytes´ selection were
lucid cell membrane and visible nuclei.
Statistical analysis
We analyzed all d ata using Prism 6.0 and 9.0 (GraphPad Software). Regarding
statistical comparisons, we used unpaired sample student’s t test for HF patients and
healthy donors. For paracrine experiment in healthy donors, we used paired sample
student’s t test. For comparisons of groups greater than two, we performed one -way
analysis of variance followed by Tukey’s post hoc test. Data were represented as mean
± SEM.
Resources Tables
Antibodies list
Antibody Catalog number Company
Anti-β actin (ACTB) ab6276 Abcam
Anti-SDHA 5839 Cell Signaling
Anti-IL1𝛽 12703 Cell Signaling
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35
Primers
Gene Sequence (5`–3`)
Human
HPRT
FP TGACACTGGCAAAACAATGCA
RP GGTCCTTTTCACCAGCAAGCT
Human
DNMT3A
FP CGAGTCCAACCCTGTGATGATTG
RP GCTGGTCTTTGCCCTGCTTTATG
Human
TNFα
FP GAGGCCAAGCCCTGGTATG
RP CGGGCCGATTGATCTCAGC
Human
IL6
FP AGCCAGAGCTGTGCAGATGAG
RP TGGCATTTGTGGTTGGGTC
Human
IL1β
FP CTAAACAGATGAAGTGCTCC
RP GGTCATTCTCCTGGAAGG
Human
SDHA
FP TGGGAACAAGAGGGCATCTG
RP CCACCACTGCATCAAATTCATG
Human
SDHB
FP ACAGCTCCCCGTATCAAGAAA
RP GCATGATCTTCGGAAGGTCAA
Human
SDHC
FP TTGCTGAGACACGTTGGTCG
RP GAGACAGAGGACGGTTTGAAC
Human
SDHD
FP TTGCTCTGCGATGGACTATTCC
RP CAAGGCATCCCCATGAACAT
Mouse
Hprt
FP GCTGACCTGCTGGATTACAT
RP TTGGGGCTGTACTGCTTAAC
Mouse
Il6
FP TCTCTGCAAGAGACTTCC
RP AGTAGGGAAGGCCGTGGTTGT
Mouse
Il1β
FP ACCCCAAAAGATGAAGGGCTG
RP TACTGCCTGCCTGAAGCTCT
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36
Supplemental Information
Figure S1. Human DNMT3A CHIP macrophages display a distinct mitochondrial
metabolism with the pro-inflammatory phenotype. (A) Representative images (left
panel) and quantification (right panel) of ROS accumulation in isolated macrophages
from HF patient with DNMT3A CHIP mutations and non-CHIP (n = 3
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37
Figure S2. Loss of DNMT3A in macrophages induces mitochondria activity under inflammatory stimulation. (A) DNMT3A mRNA
in human PBMC-derived macrophages after transfection with DNMT3A siRNA (n=3). (B) OCR measurements of permeabilized PBMC-
derived macrophages after transfection with DNMT3A siRNA (siDNMT3A) and siControl before and after the addition of substrate and
associated-complex specific inhibitors, as indicated (dashed lines) (n=3). (C) Representative images (left panel) and quantification (right
panel) of ROS accumulation in healthy PBMC -derived macrophages after knocking down with DNMT3A siRNA (n=3). ( D) OCR
measurement of human PBMC -derived macrophages after transfection with siDNMT3A with LPS stimulation (100ng/ml) for 24 hours.
Data are shown as OCR graphs (left) representative of three independent experiments, and summary bar graphs spare capacity an d
ECAR level (right) (n=3). Statistical significance was assessed by a two-tailed paired Student’s t-test and. *p <0.05, ****p< 0.0001.
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38
Figure S3. SDHA/Malate axis regulates pro -inflammatory and metabolic profile
in macrophages. (A) DNMT3A and SDHA protein level in human PBMC-derived
macrophages which are transfected with siDNMT3A and siSDHA (n=3). ( B) mRNA
expression of inflammatory cytokines including IL1β and IL6 in in human PBMC-
derived macrophages which are transfected with siDNMT3A followed by malate (5mM)
treatment for further 24 hours (n=3). Statistical significance was assessed by a two -
tailed paired Student’s t-test. *p <0.05, **p <0.01.
Figure S4: DNMT3A -associated pro -inflammatory phenotype is reduced with
dimethyl malonate treatment in macrophages. (A) mRNA expression of
inflammatory cytokines including IL1β, IL6 and SDHA and IL1β secreted protein in
PBMC-derived macrophages of HF patients with DNMT3A CHIP (n=3) and non-CHIP
(n=3) mutations upon LPS stimulation (100ng/ml) for 48 hours. Statistical significance
was assessed by a two-tailed unpaired Student’s t-test *p <0.05, **p <0.01.
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39
Table S1: COPD and Heart failure patients’ characteristics
Table S2: List of CHIP-associated somatic DNMT3A mutations identified in COPD and
HF patients
c.1667+1G>T# c.2204A>G# c.2695C>T# c.1988C>T# c.2007delC#
c.1523delT# c.1123-
1G>T# c.2194T>C# c.866delG# c.2162dupA#
c.1135C>T# c.886G>C# c.892G>A# c.2478+2T>G# c.958C>T#
c.2116G>A# c.2074C>T# c.5627C>T# c.2645G>T#
c.1154del* c.1180G>T* c.2251T>G* c.2130_2142del* c.1936+1G>A*
c.1429+1G>A* c.2099C>T* c.2206C>T* c.1904G>A* c.1171G>A*
c.2323-1G>A* c.889T>C* c.2093G>A* c.2102T>A* c.806C>T*
# Related to COPD patients
* Related to HF patients
Subset COPD patients HF patients
CHIP All Negative Positive All Negative Positive
Number 46 29 17 22 11 11
Sex
Male 60 % 62 % 58 % 86 % 73 % 100 %
Female 40 % 38 % 42 % 14 % 27 % 0 %
Age (mean) 62.15 61.97 62.47 63.52 61.64 65.60
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40
Table S3: DNA methylation pattern of inflammatory markers in DNMT3A CHIP patients. (A) DNA methylation level of inflammatory
markers in HF patients with DNMT3A CHIP (n=5) and non -CHIP (n=3). (B) DNA methylation level of inflammatory markers in COPD
patients with DNMT3A CHIP (n=15) and non-CHIP (n=10) patients.
A
Id Chr. Start End symbol entrezID
Methylation
level in
DNMT3A
chip
Methylation
level in
Non-CHIP
Difference
in
Methylation
level
comb.
p.adj.fdr
Combined
rank
ENSG00000136244 chr7 22765503 22771621 IL6 3569 0.4453 0.446 -0.001 0.487 27638
ENSG00000232810 chr6 31543344 31546113 TNF 7124 0.462 0.4612 0.001 0.487 27078
ENSG00000125538 chr2 113587328 113594480 IL1B 3553 0.397 0.421 -0.024 0.487 4061
ENSG00000169429 chr4 74606223 74609433 IL8 3576 0.340 0.342 -0.001 0.487 28597
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B
Id Chr. Start End symbol entrezID
Methylation
level in
DNMT3A
chip
Methylation
level in
Non-CHIP
Difference
in
Methylation
level
comb.
p.adj.fdr
Combined
rank
ENSG00000136244 chr7 22765503 22771621 IL6 3569 0.3958 0.4030 -0.0071 0.792 22115
ENSG00000232810 chr6 31543344 31546113 TNF 7124 0.3986 0.4196 -0.02 0.794 28298
ENSG00000125538 chr2 113587328 113594480 IL1B 3553 0.3454 0.3595 -0.014 0.792 17032
ENSG00000169429 chr4 74606223 74609433 IL8 3576 0.2861 0.3015 -0.015 0.669 27723
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Table S4. DNA methylation pattern of top differentially methylated genes. The
DNA methylation level and P value of top differentially methylated genes between
DNMT3A CHIP (HF, n=5; COPD, n= 16) and non -CHIP (HF, n=3; COPD, n=10)
patients.
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