Obesity is causally linked with the development of cardiovascular disorders. Accumulating evidence indicates that cardiovascular disease is the collateral damage of obesity-driven adipose tissue ...dysfunction that promotes a chronic inflammatory state within the organism. Adipose tissues secrete bioactive substances, referred to as adipokines, which largely function as modulators of inflammation. The microenvironment of adipose tissue will affect the adipokine secretome, having actions on remote tissues. Obesity typically leads to the upregulation of proinflammatory adipokines and the downregulation of anti-inflammatory adipokines, thereby contributing to the pathogenesis of cardiovascular diseases. In this review, we focus on the microenvironment of adipose tissue and how it influences cardiovascular disorders, including atherosclerosis and ischemic heart diseases, through the systemic actions of adipokines.
Increasing evidence shows that conventional cardiovascular risk factors are incompletely predictive of cardiovascular disease, particularly in elderly individuals, suggesting that there may still be ...unidentified causal risk factors. Although the accumulation of somatic DNA mutations is a hallmark of aging, its relevance in cardiovascular disease or other age-related conditions has been, with the exception of cancer, largely unexplored. Here, we review recent clinical and preclinical studies that have identified acquired mutations in hematopoietic stem cells and subsequent clonal hematopoiesis as a new cardiovascular risk factor and a potential major driver of atherosclerosis. Understanding the mechanisms underlying the connection between somatic mutation-driven clonal hematopoiesis and cardiovascular disease will be highly relevant in the context of personalized medicine, as it may provide key information for the design of diagnostic, preventive, or therapeutic strategies tailored to the effects of specific somatic mutations.
Abstract Obesity is a risk factor for various cardiovascular diseases including hypertension, atherosclerosis, and myocardial infarction. Recent studies aimed at understanding the microenvironment of ...adipose tissue and its impact on systemic metabolism have shed light on the pathogenesis of obesity-linked cardiovascular diseases. Adipose tissue functions as an endocrine organ by secreting multiple immune-modulatory proteins known as adipokines. Obesity leads to increased expression of pro-inflammatory adipokines and diminished expression of anti-inflammatory adipokines, resulting in the development of a chronic, low-grade inflammatory state. This adipokine imbalance is thought to be a key event in promoting both systemic metabolic dysfunction and cardiovascular disease. This review will focus on the adipose tissue microenvironment and the role of adipokines in modulating systemic inflammatory responses that contribute to cardiovascular disease.
Human aging is associated with an increased frequency of somatic mutations in hematopoietic cells. Several of these recurrent mutations, including those in the gene encoding the epigenetic modifier ...enzyme TET2, promote expansion of the mutant blood cells. This clonal hematopoiesis correlates with an increased risk of atherosclerotic cardiovascular disease. We studied the effects of the expansion of Tet2-mutant cells in atherosclerosis-prone, low-density lipoprotein receptor–deficient (Ldlr
–/–) mice. We found that partial bone marrow reconstitution with TET2-deficient cells was sufficient for their clonal expansion and led to a marked increase in atherosclerotic plaque size. TET2-deficient macrophages exhibited an increase in NLRP3 inflammasome–mediated interleukin-1β secretion. An NLRP3 inhibitor showed greater atheroprotective activity in chimeric mice reconstituted with TET2-deficient cells than in nonchimeric mice. These results support the hypothesis that somatic TET2 mutations in blood cells play a causal role in atherosclerosis.
Accumulation of cellular damage with advancing age leads to atherothrombosis and associated cardiovascular disease. Ageing is also characterized by shortening of the DNA component of telomeres, the ...specialized genetic segments located at the end of eukaryotic chromosomes that protect them from end-to-end fusions. By inducing genomic instability, replicative senescence and apoptosis, shortening of the telomeric DNA is thought to contribute to organismal ageing. In this Review, we discuss experimental and human studies that have linked telomeres and associated proteins to several factors which influence cardiovascular risk (eg, estrogens, oxidative stress, hypertension, diabetes, and psychological stress), as well as to neovascularization and the pathogenesis of atherosclerosis and heart disease. Two chief questions that remain unanswered are whether telomere shortening is cause or consequence of cardiovascular disease, and whether therapies targeting the telomere may find application in treating these disorders (eg, cell “telomerization” to engineer blood vessels of clinical value for bypass surgery, and to facilitate cell-based myocardial regeneration strategies). Given that most research to date has focused on the role of telomerase, it is also of up most importance to investigate whether alterations in additional telomere-associated proteins may contribute to the pathogenesis of cardiovascular disease.
Cancer genomes have long been known to carry a high number of somatic mutations distributed across many genes. However, recent sequencing studies have unveiled that non-cancerous cells also carry a ...considerable number of somatic mutations, which are acquired continuously through the lifespan. Accordingly, the pathophysiological relevance of somatic mutagenesis beyond cancer has become a topic of intensive research. Human genetic studies and experiments in mice have shown that some somatic mutations in the hematopoietic system provide a competitive advantage to the mutant cell and allow its clonal expansion. This phenomenon, termed clonal hematopoiesis, is typically driven by mutations in known oncogenes and tumor suppressor genes, and it is associated with a higher risk of hematological malignancies. Unexpectedly, accumulating genetic and experimental evidence strongly suggest that clonal hematopoiesis, at least when driven by certain mutations, also contributes causally to the development of cardiovascular disease and, therefore, represents a new cardiovascular risk factor. While clonal hematopoiesis is relatively common in healthy individuals, especially among the elderly, it is particularly frequent in cancer patients and survivors. Hence, it has emerged as a candidate contributor to the increased risk of cardiovascular complications in cancer patients. This review summarizes our current understanding of the connection between clonal hematopoiesis and cardiovascular disease, with a special focus on the available evidence linking clonal hematopoiesis to cardiovascular disorders that are frequent in cancer patients and survivors.
•Somatic mutations that drive clonal hematopoiesis represent a new cardiovascular risk factor.•Clonal hematopoiesis is particularly common in elderly individuals and cancer patients.•Some clonal hematopoiesis-related mutations contribute directly to cardiovascular disease.•Cytotoxic therapies facilitate clonal hematopoiesis driven by mutations in DNA damage response genes.
Recent studies have shown that hematopoietic stem cells can undergo clonal expansion secondary to somatic mutations in leukemia-related genes, thus leading to an age-dependent accumulation of mutant ...leukocytes in the blood. This somatic mutation-related clonal hematopoiesis is common in healthy older individuals, but it has been associated with an increased incidence of future cardiovascular disease. The epigenetic regulator TET2 is frequently mutated in blood cells of individuals exhibiting clonal hematopoiesis.
This study investigated whether Tet2 mutations within hematopoietic cells can contribute to heart failure in 2 models of cardiac injury.
Heart failure was induced in mice by pressure overload, achieved by transverse aortic constriction or chronic ischemia induced by the permanent ligation of the left anterior descending artery. Competitive bone marrow transplantation strategies with Tet2-deficient cells were used to mimic TET2 mutation-driven clonal hematopoiesis. Alternatively, Tet2 was specifically ablated in myeloid cells using Cre recombinase expressed from the LysM promoter.
In both experimental heart failure models, hematopoietic or myeloid Tet2 deficiency worsened cardiac remodeling and function, in parallel with increased interleukin-1beta (IL-1β) expression. Treatment with a selective NLRP3 inflammasome inhibitor protected against the development of heart failure and eliminated the differences in cardiac parameters between Tet2-deficient and wild-type mice.
Tet2 deficiency in hematopoietic cells is associated with greater cardiac dysfunction in murine models of heart failure as a result of elevated IL-1β signaling. These data suggest that individuals with TET2-mediated clonal hematopoiesis may be at greater risk of developing heart failure and respond better to IL-1β–NLRP3 inflammasome inhibition.
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Interleukin‐6 (IL‐6) is a pleiotropic cytokine with complex roles in inflammation and metabolic disease. While typically regarded as a pro‐inflammatory cytokine, multiple studies in the last 20 years ...have generated conflicting data on the role of IL‐6 in inflammation and metabolism. In a recent study in Nature Immunology, Brüning and collaborators demonstrate that IL‐6 signaling in myeloid cells attenuates obesity‐induced inflammation and insulin resistance by promoting macrophage alternative activation (Mauer et al, ). This study unveils a new and surprising anti‐inflammatory action of IL‐6 and further highlights the complex actions of this cytokine.
Most recent work from the Brüning laboratory determines an unexpected, anti‐inflammatory role of IL‐6 in obesity‐associated insulin resistance by virtue of alternative macrophage polarization.
Human aging is frequently accompanied by the acquisition of somatic mutations in the hematopoietic system that induce clonal hematopoiesis, leading to the development of a mutant clone of ...hematopoietic progenitors and leukocytes. This somatic-mutation-driven clonal hematopoiesis has been associated with an increased incidence of cardiovascular disease and type 2 diabetes, but whether this epidemiological association reflects a direct, causal contribution of mutant hematopoietic and immune cells to age-related metabolic abnormalities remains unexplored. Here, we show that inactivating mutations in the epigenetic regulator TET2, which lead to clonal hematopoiesis, aggravate age- and obesity-related insulin resistance in mice. This metabolic dysfunction is paralleled by increased expression of the pro-inflammatory cytokine IL-1β in white adipose tissue, and it is suppressed by pharmacological inhibition of NLRP3 inflammasome-mediated IL-1β production. These findings support a causal contribution of somatic TET2 mutations to insulin resistance and type 2 diabetes.
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•TET2-deficiency-driven clonal hematopoiesis aggravates insulin resistance in aged mice•TET2-deficiency-driven clonal hematopoiesis aggravates insulin resistance in obese mice•TET2-deficiency-driven clonal hematopoiesis increases IL-1β levels in adipose tissue•NLRP3 inhibition prevents the effects of TET2-deficient cells on insulin sensitivity
Somatic-mutation-driven clonal hematopoiesis is emerging as a potent risk factor for a variety of age-related conditions. Fuster et al. show that clonal hematopoiesis driven by TET2 mutations aggravates insulin resistance in mice. These findings support a causal contribution of somatic TET2 mutations to metabolic syndrome and type 2 diabetes.
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