Clonal haematopoiesis induces a pro-inflammatory monocyte phenotype in HF

Brain macrophage development, diversity and dysregulation in health and disease

Brain macrophages include microglia in the parenchyma, border-associated macrophages in the meningeal-choroid plexus-perivascular space, and monocyte-derived macrophages that infiltrate the brain under various disease conditions. The vast heterogeneity of these cells has been elucidated over the last decade using revolutionary multiomics technologies. As such, we can now start to define these various macrophage populations according to their ontogeny and their diverse functional programs during brain development, homeostasis and disease pathogenesis. In this review, we first outline the critical roles played by brain macrophages during development and healthy aging. We then discuss how brain macrophages might undergo reprogramming and contribute to neurodegenerative disorders, autoimmune diseases, and glioma. Finally, we speculate about the most recent and ongoing discoveries that are prompting translational attempts to leverage brain macrophages as prognostic markers or therapeutic targets for diseases that affect the brain.

Clonal hematopoiesis driven by DNMT3A and TET2 mutations: role in monocyte and macrophage biology and atherosclerotic cardiovascular disease

PURPOSE OF REVIEW

Clonal hematopoiesis of indeterminate potential (CHIP), defined by the presence of somatic mutations in hematopoietic cells, is associated with advanced age and increased mortality due to cardiovascular disease. Gene mutations in DNMT3A and TET2 are the most frequently identified variants among patients with CHIP and provide selective advantage that spurs clonal expansion and myeloid skewing. Although DNMT3A and TET2 appear to have opposing enzymatic influence on DNA methylation, mounting data has characterized convergent inflammatory pathways, providing insights to how CHIP may mediate atherosclerotic cardiovascular disease (ASCVD).

RECENT FINDINGS

We review a multitude of studies that characterize aberrant inflammatory signaling as result of DNMT3A and TET2 deficiency in monocytes and macrophages, immune cells with prominent roles in atherosclerosis. Although specific DNA methylation signatures associated with these known epigenetic regulators have been identified, many studies have also characterized diverse modulatory functions of DNTM3A and TET2 that urge cell and context-specific experimental studies to further define how DNMT3A and TET2 may nonenzymatically activate inflammatory pathways with clinically meaningful consequences.

SUMMARY

CHIP, common in elderly individuals, provides an opportunity understand and potentially modify age-related chronic inflammatory ASCVD risk.

Clonal hematopoiesis and cardiovascular disease: deciphering interconnections

Cardiovascular and oncological diseases represent the global major causes of death. For both, a novel and far-reaching risk factor has been identified: clonal hematopoiesis (CH). CH is defined as clonal expansion of peripheral blood cells on the basis of somatic mutations, without overt hematological malignancy. The most commonly affected genes are TET2, DNMT3A, ASXL1 and JAK2. By the age of 70, at least 20-50% of all individuals carry a CH clone, conveying a striking clinical impact by increasing all-cause mortality by 40%. This is due predominantly to a nearly two-fold increase of cardiovascular risk, but also to an elevated risk of malignant transformation. Individuals with CH show not only increased risk for, but also worse outcomes after arteriosclerotic events, such as stroke or myocardial infarction, decompensated heart failure and cardiogenic shock. Elevated cytokine levels, dysfunctional macrophage activity and activation of the inflammasome suggest that a vicious cycle of chronic inflammation and clonal expansion represents the major functional link. Despite the apparently high impact of this entity, awareness, functional understanding and especially clinical implications still require further research. This review provides an overview of the current knowledge of CH and its relation to cardiovascular and hematological diseases. It focuses on the basic functional mechanisms in the interplay between atherosclerosis, inflammation and CH, identifies issues for further research and considers potential clinical implications.