The AIM2 inflammasome exacerbates atherosclerosis in clonal haematopoiesis

Spotlight on pyroptosis: role in pathogenesis and therapeutic potential of ocular diseases

Pyroptosis is a programmed cell death characterized by swift plasma membrane disruption and subsequent release of cellular contents and pro-inflammatory mediators (cytokines), including IL‐1β and IL‐18. It differs from other types of programmed cell death such as apoptosis, autophagy, necroptosis, ferroptosis, and NETosis in terms of its morphology and mechanism. As a recently discovered form of cell death, pyroptosis has been demonstrated to be involved in the progression of multiple diseases. Recent studies have also suggested that pyroptosis is linked to various ocular diseases. In this review, we systematically summarized and discussed recent scientific discoveries of the involvement of pyroptosis in common ocular diseases, including diabetic retinopathy, age-related macular degeneration, AIDS-related human cytomegalovirus retinitis, glaucoma, dry eye disease, keratitis, uveitis, and cataract. We also organized new and emerging evidence suggesting that pyroptosis signaling pathways may be potential therapeutic targets in ocular diseases, hoping to provide a summary of overall intervention strategies and relevant multi-dimensional evaluations for various ocular diseases, as well as offer valuable ideas for further research and development from the perspective of pyroptosis.

Therapy-Related Clonal Hematopoiesis: A New Link Between Cancer and Cardiovascular Disease

Clonal hematopoiesis is a precancerous state that is recognized as a new causal risk factor for cardiovascular disease. Therapy-related clonal hematopoiesis is a condition that is often found in cancer survivors. These clonal expansions are caused by mutations in DNA damage-response pathway genes that allow hematopoietic stem cells to undergo positive selection in response to the genotoxic stress. These mutant cells increasingly give rise to progeny leukocytes that display enhanced proinflammatory properties. Recent experimental studies suggest that therapy-related clonal hematopoiesis may contribute to the medium- to long-term risk of genotoxic therapies on the cardiovascular system.

T cell cholesterol efflux suppresses apoptosis and senescence and increases atherosclerosis in middle aged mice

Atherosclerosis is a chronic inflammatory disease driven by hypercholesterolemia. During aging, T cells accumulate cholesterol, potentially affecting inflammation. However, the effect of cholesterol efflux pathways mediated by ATP-binding cassette A1 and G1 (ABCA1/ABCG1) on T cell-dependent age-related inflammation and atherosclerosis remains poorly understood. In this study, we generate mice with T cell-specific Abca1/Abcg1-deficiency on the low-density-lipoprotein-receptor deficient (Ldlr^-/-) background. T cell Abca1/Abcg1-deficiency decreases blood, lymph node, and splenic T cells, and increases T cell activation and apoptosis. T cell Abca1/Abcg1-deficiency induces a premature T cell aging phenotype in middle-aged (12-13 months) Ldlr^-/- mice, reflected by upregulation of senescence markers. Despite T cell senescence and enhanced T cell activation, T cell Abca1/Abcg1-deficiency decreases atherosclerosis and aortic inflammation in middle-aged Ldlr^-/- mice, accompanied by decreased T cells in atherosclerotic plaques. We attribute these effects to T cell apoptosis downstream of T cell activation, compromising T cell functionality. Collectively, we show that T cell cholesterol efflux pathways suppress T cell apoptosis and senescence, and induce atherosclerosis in middle-aged Ldlr^-/- mice.

Game of clones: Diverse implications for clonal hematopoiesis in lymphoma and multiple myeloma

Clonal hematopoiesis (CH) refers to the disproportionate expansion of hematopoietic stem cell clones and their corresponding progeny following the acquisition of somatic mutations. CH is common at the time of diagnosis in patients with blood cancers, including multiple myeloma (MM) and lymphoma. The presence of CH mutations correlates with IL-6 mediated inflammation and may result in lymphoma or MM modulation through microenvironment effects or by manifestations of the mutations themselves within the founding tumor clone. As might be expected with a variety of mutations and multiple potential mechanisms, CH exerts context-dependent effects, being protective in some settings and harmful in others. Though CH is very common in patients with hematologic malignancies, how it intersects with therapy and the natural disease course of these cancers are active areas of investigation. In lymphomas and MM specifically, patients have high rates of CH at diagnosis and are subsequently exposed to therapies, such as cytotoxic chemotherapy, that can cause CH progression to overt hematologic malignancy. The expanding diversity of treatment modalities for these cancers also increases the opportunities for CH to impact clinical outcome and modulate clinical responses. Here we review the basic biology and known health effects of CH, and we focus on the clinical relevance of CH in lymphoma and MM.

Single Cell Biology: Exploring Somatic Cell Behaviors, Competition and Selection in Chronic Disease

The full range of cell functions is under-determined in most human diseases. The evidence that somatic cell competition and clonal imbalance play a role in non-neoplastic chronic disease reveal a need for a dedicated effort to explore single cell function if we are to understand the mechanisms by which cell population behaviors influence disease. It will be vital to document not only the prevalent pathologic behaviors but also those beneficial functions eliminated or suppressed by competition. An improved mechanistic understanding of the role of somatic cell biology will help to stratify chronic disease, define more precisely at an individual level the role of environmental factors and establish principles for prevention and potential intervention throughout the life course and across the trajectory from wellness to disease.

Myeloid LXR (Liver X Receptor) Deficiency Induces Inflammatory Gene Expression in Foamy Macrophages and Accelerates Atherosclerosis

BACKGROUND

Cholesterol loaded macrophage foam cells are a prominent feature of atherosclerotic plaques. Single-cell RNA sequencing has identified foam cells as TREM2 (triggering receptor expressed on myeloid cells 2) positive populations with low expression of inflammatory genes, resembling the TREM2 positive microglia of neurodegenerative diseases. Cholesterol loading of macrophages in vitro results in activation of LXR (liver X receptor) transcription factors and suppression of inflammatory genes.

METHODS

To test the hypothesis that LXRs mediate anti-inflammatory effects in Trem2 expressing atherosclerotic plaque foam cells, we performed RNA profiling on plaque cells from hypercholesterolemic mice with myeloid LXR deficiency.

RESULTS

Myeloid LXR deficiency led to a dramatic increase in atherosclerosis with increased monocyte entry, foam cell formation, and plaque inflammation. Bulk cell-RNA profiling of plaque myeloid cells showed prominent upregulation of inflammatory mediators including oxidative, chemokine, and chemotactic genes. Single-cell RNA sequencing revealed increased numbers of foamy TREM2-expressing macrophages; however, these cells had reduced expression of the Trem2 gene expression module, including phagocytic and cholesterol efflux genes, and had switched to a proinflammatory and proliferative phenotype. Expression of Trem2 was suppressed by inflammatory signals but not directly affected by LXR activation in bone marrow-derived macrophages.

CONCLUSIONS

Our current studies reveal the key role of macrophage LXRs in promoting the Trem2 gene expression program and in suppressing inflammation in foam cells of atherosclerotic plaques.

Antiatherosclerotic effect of dehydrocorydaline on ApoE-/- mice: inhibition of macrophage inflammation

Despite improvements in cardiovascular disease (CVD) outcomes by cholesterol-lowering statin therapy, the high rate of CVD is still a great concern worldwide. Dehydrocorydaline (DHC) is an alkaloidal compound isolated from the traditional Chinese herb Corydalis yanhusuo. Emerging evidence shows that DHC has anti-inflammatory and antithrombotic benefits, but whether DHC exerts any antiatherosclerotic effects remains unclear. Our study revealed that intraperitoneal (i.p.) injection of DHC in apolipoprotein E-deficient (ApoE^-/-) mice not only inhibited atherosclerosis development but also improved aortic compliance and increased plaque stability. In addition, DHC attenuated systemic and vascular inflammation in ApoE^-/- mice. As macrophage inflammation plays an essential role in the pathogenesis of atherosclerosis, we next examined the direct effects of DHC on bone marrow-derived macrophages (BMDMs) in vitro. Our RNA-seq data revealed that DHC dramatically decreased the levels of proinflammatory gene clusters. We verified that DHC significantly downregulated proinflammatory interleukin (IL)-1β and IL-18 mRNA levels in a time- and concentration-dependent manner. Furthermore, DHC decreased lipopolysaccharide (LPS)-induced inflammation in BMDMs, as evidenced by the reduced protein levels of CD80, iNOS, NLRP3, IL-1β, and IL-18. Importantly, DHC attenuated LPS-induced activation of p65 and the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. Thus, we conclude that DHC ameliorates atherosclerosis in ApoE^-/- mice by inhibiting inflammation, likely by targeting macrophage p65- and ERK1/2-mediated pathways.

Cardiovascular Disease in Myeloproliferative Neoplasms: JACC: CardioOncology State-of-the-Art Review

Myeloproliferative neoplasms are associated with increased risk for thrombotic complications. These conditions most commonly involve somatic mutations in genes that lead to constitutive activation of the Janus-associated kinase signaling pathway (eg, Janus kinase 2, calreticulin, myeloproliferative leukemia protein). Acquired gain-of-function mutations in these genes, particularly Janus kinase 2, can cause a spectrum of disorders, ranging from clonal hematopoiesis of indeterminate potential, a recently recognized age-related promoter of cardiovascular disease, to frank hematologic malignancy. Beyond thrombosis, patients with myeloproliferative neoplasms can develop other cardiovascular conditions, including heart failure and pulmonary hypertension. The authors review the pathophysiologic mechanisms of cardiovascular complications of myeloproliferative neoplasms, which involve inflammation, prothrombotic and profibrotic factors (including transforming growth factor-beta and lysyl oxidase), and abnormal function of circulating clones of mutated leukocytes and platelets from affected individuals. Anti-inflammatory therapies may provide cardiovascular benefit in patients with myeloproliferative neoplasms, a hypothesis that requires rigorous evaluation in clinical trials.

Novel role for caspase 1 inhibitor VX765 in suppressing NLRP3 inflammasome assembly and atherosclerosis via promoting mitophagy and efferocytosis

Atherosclerosis is a maladaptive chronic inflammatory disease, which remains the leading cause of death worldwide. The NLRP3 inflammasome constitutes a major driver of atherosclerosis, yet the mechanism of action is poorly understood. Mitochondrial dysfunction is essential for NLRP3 inflammasome activation. However, whether activated NLRP3 inflammasome exacerbates mitochondrial dysfunction remains to be further elucidated. Herein, we sought to address these issues applying VX765, a well-established inhibitor of caspase 1. VX765 robustly restrains caspase 1-mediated interleukin-1β production and gasdermin D processing. Our study assigned VX765 a novel role in antagonizing NLRP3 inflammasome assembly and activation. VX765 mitigates mitochondrial damage induced by activated NLRP3 inflammasome, as evidenced by decreased mitochondrial ROS production and cytosolic release of mitochondrial DNA. VX765 blunts caspase 1-dependent cleavage and promotes mitochondrial recruitment and phosphorylation of Parkin, a key mitophagy regulator. Functionally, VX765 facilitates mitophagy, efferocytosis and M2 polarization of macrophages. It also impedes foam cell formation, migration and pyroptosis of macrophages. VX765 boosts autophagy, promotes efferocytosis, and alleviates vascular inflammation and atherosclerosis in both ApoE^-/- and Ldlr^-/- mice. However, these effects of VX765 were abrogated upon ablation of Nlrp3 in ApoE^-/- mice. This work provides mechanistic insights into NLRP3 inflammasome assembly and this inflammasome in dictating atherosclerosis. This study highlights that manipulation of caspase 1 paves a new avenue to treatment of atherosclerotic cardiovascular disease.

Targeting Microtubules for the Treatment of Heart Disease

Heart disease remains the leading cause of morbidity and mortality worldwide. With the advancement of modern technology, the role(s) of microtubules in the pathogenesis of heart disease has become increasingly apparent, though currently there are limited treatments targeting microtubule-relevant mechanisms. Here, we review the functions of microtubules in the cardiovascular system and their specific adaptive and pathological phenotypes in cardiac disorders. We further explore the use of microtubule-targeting drugs and highlight promising druggable therapeutic targets for the future treatment of heart diseases.

Erythroid lineage Jak2V617F expression promotes atherosclerosis through erythrophagocytosis and macrophage ferroptosis

Elevated hematocrit is associated with cardiovascular risk; however, the causality and mechanisms are unclear. The JAK2^V617F (Jak2^VF) mutation increases cardiovascular risk in myeloproliferative disorders and in clonal hematopoiesis. Jak2^VF mice with elevated WBCs, platelets, and RBCs display accelerated atherosclerosis and macrophage erythrophagocytosis. To investigate whether selective erythroid Jak2^VF expression promotes atherosclerosis, we developed hyperlipidemic erythropoietin receptor Cre mice that express Jak2^VF in the erythroid lineage (VFEpoR mice). VFEpoR mice without elevated blood cell counts showed increased atherosclerotic plaque necrosis, erythrophagocytosis, and ferroptosis. Selective induction of erythrocytosis with low-dose erythropoietin further exacerbated atherosclerosis with prominent ferroptosis, lipid peroxidation, and endothelial damage. VFEpoR RBCs had reduced antioxidant defenses and increased lipid hydroperoxides. Phagocytosis of human or murine WT or JAK2^VF RBCs by WT macrophages induced ferroptosis, which was prevented by the ferroptosis inhibitor liproxstatin-1. Liproxstatin-1 reversed increased atherosclerosis, lipid peroxidation, ferroptosis, and endothelial damage in VFEpoR mice and in Jak2^VF chimeric mice simulating clonal hematopoiesis, but had no impact in controls. Erythroid lineage Jak2^VF expression led to qualitative and quantitative defects in RBCs that exacerbated atherosclerosis. Phagocytosis of RBCs by plaque macrophages promoted ferroptosis, suggesting a therapeutic target for reducing RBC-mediated cardiovascular risk.

The Association of Serum AIM2 Level with the Prediction and Short-Term Prognosis of Coronary Artery Disease

Objective. Coronary artery disease (CAD), one of the commonest cardiovascular diseases, has high morbidity and mortality. Absent in melanoma 2 (AIM2) is involved in atherosclerosis, and no clinical trials have explored the association between AIM2 and CAD. Therefore, this study was aimed at evaluating the predictive and short-term prognostic value of AIM2 for CAD. Methods. 279 patients who underwent coronary angiography were enrolled in this study. The AIM2 level was detected from the serum of collected artery blood samples. The association of serum AIM2 level with the prediction and short-term prognosis of CAD was further assessed. Results. The serum AIM2 level of the CAD group was significantly higher than the control group ( $5.5\pm 2.1$ vs. $3.7\pm 1.7$ ; $p<0.001$ ). AIM2 was demonstrated to be the risk factor of CAD [odds ratio, 1.589; 95% confidence interval (CI), 1.346-1.876; $p<0.001$ ]. The area under the receiver operating characteristic (ROC) curve of 0.738 showed the diagnostic value of AIM2 in CAD. Additionally, AIM2 was an independent predictor of major adverse cardiovascular events (hazard ratio, 1.453; 95% CI, 1.086-1.945; $p=0.012$ ), and CAD patients with high AIM2 levels (>4.9 ng/mL) had a markedly lower survival rate (log-rank $p=0.040$ ). Conclusions. The serum AIM2 $\text{level}>4.9$  ng/mL can predict CAD to a certain extent. AIM2 might be an independent predictor of its short-term poor prognosis.

Atherosclerosis: Recent developments

Atherosclerosis is an inflammatory disease of the large arteries that is the major cause of cardiovascular disease (CVD) and stroke. Here, we review the current understanding of the molecular, cellular, genetic, and environmental contributions to atherosclerosis, from both individual pathway and systems perspectives. We place an emphasis on recent developments, some of which have yielded unexpected biology, including previously unknown heterogeneity of inflammatory and smooth muscle cells in atherosclerotic lesions, roles for senescence and clonal hematopoiesis, and links to the gut microbiome.

Macrophage Cx43 Is Necessary for Fibroblast Cytosolic Calcium and Lung Fibrosis After Injury

Macrophages are paracrine signalers that regulate tissular responses to injury through interactions with parenchymal cells. Connexin hemichannels have recently been shown to mediate efflux of ATP by macrophages, with resulting cytosolic calcium responses in adjacent cells. Here we report that lung macrophages with deletion of connexin 43 (MacΔCx43) had decreased ATP efflux into the extracellular space and induced a decreased cytosolic calcium response in co-cultured fibroblasts compared to WT macrophages. Furthermore, MacΔCx43 mice had decreased lung fibrosis after bleomycin-induced injury. Interrogating single cell data for human and mouse, we found that P2rx4 was the most highly expressed ATP receptor and calcium channel in lung fibroblasts and that its expression was increased in the setting of fibrosis. Fibroblast-specific deletion of P2rx4 in mice decreased lung fibrosis and collagen expression in lung fibroblasts in the bleomycin model. Taken together, these studies reveal a Cx43-dependent profibrotic effect of lung macrophages and support development of fibroblast P2rx4 as a therapeutic target for lung fibrosis.

Immune and Inflammatory Networks in Myocardial Infarction: Current Research and Its Potential Implications for the Clinic

Despite recent scientific and technological advances, myocardial infarction (MI) still represents a major global health problem, leading to high morbidity and mortality worldwide. During the post-MI wound healing process, dysregulated immune inflammatory pathways and failure to resolve inflammation are associated with maladaptive left ventricular remodeling, progressive heart failure, and eventually poor outcomes. Given the roles of immune cells in the host response against tissue injury, understanding the involved cellular subsets, sources, and functions is essential for discovering novel therapeutic strategies that preserve the protective immune system and promote optimal healing. This review discusses the cellular effectors and molecular signals across multi-organ systems, which regulate the inflammatory and reparative responses after MI. Additionally, we summarize the recent clinical and preclinical data that propel conceptual revolutions in cardiovascular immunotherapy.

Foam Cells in Atherosclerosis: Novel Insights Into Its Origins, Consequences, and Molecular Mechanisms

Foam cells play a vital role in the initiation and development of atherosclerosis. This review aims to summarize the novel insights into the origins, consequences, and molecular mechanisms of foam cells in atherosclerotic plaques. Foam cells are originated from monocytes as well as from vascular smooth muscle cells (VSMC), stem/progenitor cells, and endothelium cells. Novel technologies including lineage tracing and single-cell RNA sequencing (scRNA-seq) have revolutionized our understanding of subtypes of monocyte- and VSMC-derived foam cells. By using scRNA-seq, three main clusters including resident-like, inflammatory, and triggering receptor expressed on myeloid cells-2 (Trem2 ^hi ) are identified as the major subtypes of monocyte-derived foam cells in atherosclerotic plaques. Foam cells undergo diverse pathways of programmed cell death including apoptosis, autophagy, necroptosis, and pyroptosis, contributing to the necrotic cores of atherosclerotic plaques. The formation of foam cells is affected by cholesterol uptake, efflux, and esterification. Novel mechanisms including nuclear receptors, non-coding RNAs, and gut microbiota have been discovered and investigated. Although the heterogeneity of monocytes and the complexity of non-coding RNAs make obstacles for targeting foam cells, further in-depth research and therapeutic exploration are needed for the better management of atherosclerosis.

Association of Clonal Hematopoiesis of Indeterminate Potential with Worse Kidney Function and Anemia in Two Cohorts of Patients with Advanced Chronic Kidney Disease

BACKGROUND

Clonal hematopoiesis of indeterminate potential (CHIP) is an inflammatory premalignant disorder resulting from acquired genetic mutations in hematopoietic stem cells. This condition is common in aging populations and associated with cardiovascular morbidity and overall mortality, but its role in CKD is unknown.

METHODS

We performed targeted sequencing to detect CHIP mutations in two independent cohorts of 87 and 85 adults with an eGFR<60 ml/min per 1.73m2. We also assessed kidney function, hematologic, and mineral bone disease parameters cross-sectionally at baseline, and collected creatinine measurements over the following 5-year period.

RESULTS

At baseline, CHIP was detected in 18 of 87 (21%) and 25 of 85 (29%) cohort participants. Participants with CHIP were at higher risk of kidney failure, as predicted by the Kidney Failure Risk Equation (KFRE), compared with those without CHIP. Individuals with CHIP manifested a 2.2-fold increased risk of a 50% decline in eGFR or ESKD over 5 years of follow-up (hazard ratio 2.2; 95% confidence interval, 1.2 to 3.8) in a Cox proportional hazard model adjusted for age, sex, and baseline eGFR. The addition of CHIP to 2-year and 5-year calibrated KFRE risk models improved ESKD predictions. Those with CHIP also had lower hemoglobin, higher ferritin, and higher red blood cell mean corpuscular volume versus those without CHIP.

CONCLUSIONS

In this exploratory analysis of individuals with preexisting CKD, CHIP was associated with higher baseline KFRE scores, greater progression of CKD, and anemia. Further research is needed to define the nature of the relationship between CHIP and kidney disease progression.

Emerging Roles of Inflammasomes in Cardiovascular Diseases

Cardiovascular diseases are known as the leading cause of morbidity and mortality worldwide. As an innate immune signaling complex, inflammasomes can be activated by various cardiovascular risk factors and regulate the activation of caspase-1 and the production and secretion of proinflammatory cytokines such as IL-1β and IL-18. Accumulating evidence supports that inflammasomes play a pivotal role in the progression of atherosclerosis, myocardial infarction, and heart failure. The best-known inflammasomes are NLRP1, NLRP3, NLRC4, and AIM2 inflammasomes, among which NLRP3 inflammasome is the most widely studied in the immune response and disease development. This review focuses on the activation and regulation mechanism of inflammasomes, the role of inflammasomes in cardiovascular diseases, and the research progress of targeting NLRP3 inflammasome and IL-1β for related disease intervention.

Single-cell technologies to decipher cardiovascular diseases

Cardiovascular disease remains the leading cause of death worldwide. A deeper understanding of the multicellular composition and molecular processes may help to identify novel therapeutic strategies. Single-cell technologies such as single-cell or single-nuclei RNA sequencing provide expression profiles of individual cells and allow for dissection of heterogeneity in tissue during health and disease. This review will summarize (i) how these novel technologies have become critical for delineating mechanistic drivers of cardiovascular disease, particularly, in humans and (ii) how they might serve as diagnostic tools for risk stratification or individualized therapy. The review will further discuss technical pitfalls and provide an overview of publicly available human and mouse data sets that can be used as a resource for research.

Clonal Hematopoiesis Analyses in Clinical, Epidemiologic, and Genetic Aging Studies to Unravel Underlying Mechanisms of Age-Related Dysfunction in Humans

Aging is characterized by increased mortality, functional decline, and exponential increases in the incidence of diseases such as cancer, stroke, cardiovascular disease, neurological disease, respiratory disease, etc. Though the role of aging in these diseases is widely accepted and considered to be a common denominator, the underlying mechanisms are largely unknown. A significant age-related feature observed in many population cohorts is somatic mosaicism, the detectable accumulation of somatic mutations in multiple cell types and tissues, particularly those with high rates of cell turnover (e.g., skin, liver, and hematopoietic cells). Somatic mosaicism can lead to the development of cellular clones that expand with age in otherwise normal tissues. In the hematopoietic system, this phenomenon has generally been referred to as "clonal hematopoiesis of indeterminate potential" (CHIP) when it applies to a subset of clones in which mutations in driver genes of hematologic malignancies are found. Other mechanisms of clonal hematopoiesis, including large chromosomal alterations, can also give rise to clonal expansion in the absence of conventional CHIP driver gene mutations. Both types of clonal hematopoiesis (CH) have been observed in studies of animal models and humans in association with altered immune responses, increased mortality, and disease risk. Studies in murine models have found that some of these clonal events are involved in abnormal inflammatory and metabolic changes, altered DNA damage repair and epigenetic changes. Studies in long-lived individuals also show the accumulation of somatic mutations, yet at this advanced age, carriership of somatic mutations is no longer associated with an increased risk of mortality. While it remains to be elucidated what factors modify this genotype-phenotype association, i.e., compensatory germline genetics, cellular context of the mutations, protective effects to diseases at exceptional age, it points out that the exceptionally long-lived are key to understand the phenotypic consequences of CHIP mutations. Assessment of the clinical significance of somatic mutations occurring in blood cell types for age-related outcomes in human populations of varied life and health span, environmental exposures, and germline genetic risk factors will be valuable in the development of personalized strategies tailored to specific somatic mutations for healthy aging.

Inflammasome and Its Therapeutic Targeting in Rheumatoid Arthritis

Inflammasome is a cytoplasmic multiprotein complex that facilitates the clearance of exogenous microorganisms or the recognition of endogenous danger signals, which is critically involved in innate inflammatory response. Excessive or abnormal activation of inflammasomes has been shown to contribute to the development of various diseases including autoimmune diseases, neurodegenerative changes, and cancers. Rheumatoid arthritis (RA) is a chronic and complex autoimmune disease, in which inflammasome activation plays a pivotal role in immune dysregulation and joint inflammation. This review summarizes recent findings on inflammasome activation and its effector mechanisms in the pathogenesis of RA and potential development of therapeutic targeting of inflammasome for the immunotherapy of RA.

Exploring the Associations Between Clonal Hematopoiesis of Indeterminate Potential, Myeloid Malignancy, and Atherosclerosis

Outgrowth of a mutated hematopoietic stem/progenitor clone and its descendants, also known as clonal hematopoiesis, has long been considered as either a potential forerunner to hematologic malignancy or as a clinically silent phase in leukemia that antedates symptomatic disease. That definition of clonal hematopoiesis has now been expanded to encompass patients who harbor specific genetic/epigenetic mutations that lead to clonal hematopoiesis of indeterminate potential (CHIP) and, with it, a relatively heightened risk for both myeloid malignancy and atherosclerosis during aging. In this review, we provide contemporary insights into the cellular and molecular basis for CHIP and explore the relationship of CHIP to myeloid malignancy and atherosclerosis. We also discuss emerging strategies to explore CHIP biology and clinical targeting of CHIP related malignancy and cardiovascular disease.

Atherosclerosis and multi-organ-associated pathologies

Atherosclerosis is a chronic inflammatory disease of the vascular system that is characterized by the deposition of modified lipoproteins, accumulation of immune cells, and formation of fibrous tissue within the vessel wall. The disease occurs in vessels throughout the body and affects the functions of almost all organs including the lymphoid system, bone marrow, heart, brain, pancreas, adipose tissue, liver, kidneys, and gastrointestinal tract. Atherosclerosis and associated factors influence these tissues via the modulation of local vascular functions, induction of cholesterol-associated pathologies, and regulation of local immune responses. In this review, we discuss how atherosclerosis interferers with functions of different organs via several common pathways and how the disturbance of immunity in atherosclerosis can result in disease-provoking dysfunctions in multiple tissues. Our growing appreciation of the implication of atherosclerosis and associated microenvironmental conditions in the multi-organ pathology promises to influence our understanding of CVD-associated disease pathologies and to provide new therapeutic opportunities.

Modafinil Reduces Neuronal Pyroptosis and Cognitive Decline After Sleep Deprivation

Sleep deprivation (SD) induces systemic inflammation that promotes neuronal pyroptosis. The purpose of this study was to investigate the effect of an antioxidant modafinil on neuronal pyroptosis and cognitive decline following SD. Using a mouse model of SD, we found that modafinil improved learning and memory, reduced proinflammatory factor (IL-1β, TNF-α, and IL-6) production, and increased the expression of anti-inflammatory factors (IL-10). Modafinil treatment attenuated inflammasome activity and reduced neuronal pyroptosis involving the NLRP3/NLRP1/NLRC4-caspase-1-IL-1β pathway. In addition, modafinil induced an upregulation of brain-derived neurotrophic factor (BDNF) and synaptic activity. These results suggest that modafinil reduces neuronal pyroptosis and cognitive decline following SD. These effects should be further investigated in future studies to benefit patients with sleep disorders.

Clonal Hematopoiesis Is Associated With Higher Risk of Stroke

BACKGROUND AND PURPOSE

Clonal hematopoiesis of indeterminate potential (CHIP) is a novel age-related risk factor for cardiovascular disease-related morbidity and mortality. The association of CHIP with risk of incident ischemic stroke was reported previously in an exploratory analysis including a small number of incident stroke cases without replication and lack of stroke subphenotyping. The purpose of this study was to discover whether CHIP is a risk factor for ischemic or hemorrhagic stroke.

METHODS

We utilized plasma genome sequence data of blood DNA to identify CHIP in 78 752 individuals from 8 prospective cohorts and biobanks. We then assessed the association of CHIP and commonly mutated individual CHIP driver genes (DNMT3A, TET2, and ASXL1) with any stroke, ischemic stroke, and hemorrhagic stroke.

RESULTS

CHIP was associated with an increased risk of total stroke (hazard ratio, 1.14 [95% CI, 1.03-1.27]; P=0.01) after adjustment for age, sex, and race. We observed associations with CHIP with risk of hemorrhagic stroke (hazard ratio, 1.24 [95% CI, 1.01-1.51]; P=0.04) and with small vessel ischemic stroke subtypes. In gene-specific association results, TET2 showed the strongest association with total stroke and ischemic stroke, whereas DMNT3A and TET2 were each associated with increased risk of hemorrhagic stroke.

CONCLUSIONS

CHIP is associated with an increased risk of stroke, particularly with hemorrhagic and small vessel ischemic stroke. Future studies clarifying the relationship between CHIP and subtypes of stroke are needed.

The Applications of Single-Cell RNA Sequencing in Atherosclerotic Disease

Atherosclerosis still is the primary cause of death worldwide. Our characterization of the atherosclerotic lesion is mainly rooted in definitions based on pathological descriptions. We often speak in absolutes regarding plaque phenotypes: vulnerable vs. stable plaques or plaque rupture vs. plaque erosion. By focusing on these concepts, we may have oversimplified the atherosclerotic disease and its mechanisms. The widely used definitions of pathology-based plaque phenotypes can be fine-tuned with observations made with various -omics techniques. Recent advancements in single-cell transcriptomics provide the opportunity to characterize the cellular composition of the atherosclerotic plaque. This additional layer of information facilitates the in-depth characterization of the atherosclerotic plaque. In this review, we discuss the impact that single-cell transcriptomics may exert on our current understanding of atherosclerosis.

Macrophage Jak2 deficiency accelerates atherosclerosis through defects in cholesterol efflux

Atherosclerosis is a chronic inflammatory condition in which macrophages play a major role. Janus kinase 2 (JAK2) is a pivotal molecule in inflammatory and metabolic signaling, and Jak2^V617F activating mutation has recently been implicated with enhancing clonal hematopoiesis and atherosclerosis. To determine the essential in vivo role of macrophage (M)-Jak2 in atherosclerosis, we generate atherosclerosis-prone ApoE-null mice deficient in M-Jak2. Contrary to our expectation, these mice exhibit increased plaque burden with no differences in macrophage proliferation, recruitment or bone marrow clonal expansion. Notably, M-Jak2-deficient bone marrow derived macrophages show a significant defect in cholesterol efflux. Pharmacologic JAK2 inhibition with ruxolitinib also leads to defects in cholesterol efflux and accelerates atherosclerosis. Liver X receptor agonist abolishes the efflux defect and attenuates the accelerated atherosclerosis that occurs with M-Jak2 deficiency. Macrophages of individuals with the Jak2^V617F mutation show increased efflux which is normalized when treated with a JAK2 inhibitor. Together, M-Jak2-deficiency leads to accelerated atherosclerosis primarily through defects in cholesterol efflux from macrophages.

Cytosolic escape of mitochondrial DNA triggers cGAS-STING-NLRP3 axis-dependent nucleus pulposus cell pyroptosis

Low back pain (LBP) is a major musculoskeletal disorder and the socioeconomic problem with a high prevalence that mainly involves intervertebral disc (IVD) degeneration, characterized by progressive nucleus pulposus (NP) cell death and the development of an inflammatory microenvironment in NP tissue. Excessively accumulated cytosolic DNA acts as a damage-associated molecular pattern (DAMP) that is monitored by the cGAS-STING axis to trigger the immune response in many degenerative diseases. NLRP3 inflammasome-dependent pyroptosis is a type of inflammatory programmed death that promotes a chronic inflammatory response and tissue degeneration. However, the relationship between the cGAS-STING axis and NLRP3 inflammasome-induced pyroptosis in the pathogenesis of IVD degeneration remains unclear. Here, we used magnetic resonance imaging (MRI) and histopathology to demonstrate that cGAS, STING, and NLRP3 are associated with the degree of IVD degeneration. Oxidative stress induced cGAS-STING axis activation and NLRP3 inflammasome-mediated pyroptosis in a STING-dependent manner in human NP cells. Interestingly, the canonical morphological and functional characteristics of mitochondrial permeability transition pore (mPTP) opening with the cytosolic escape of mitochondrial DNA (mtDNA) were observed in human NP cells under oxidative stress. Furthermore, the administration of a specific pharmacological inhibitor of mPTP and self-mtDNA cytosolic leakage effectively reduced NLRP3 inflammasome-mediated pyroptotic NP cell death and microenvironmental inflammation in vitro and degenerative progression in a rat disc needle puncture model. Collectively, these data highlight the critical roles of the cGAS-STING-NLRP3 axis and pyroptosis in the progression of IVD degeneration and provide promising therapeutic approaches for discogenic LBP.

Somatic Mosaicism in Biology and Disease

Contrary to earlier beliefs, every cell in the individual is genetically different due to somatic mutations. Consequently, tissues become a mixture of cells with distinct genomes, a phenomenon termed somatic mosaicism. Recent advances in genome sequencing technology have unveiled possible causes of mutations and how they shape the unique mutational landscape of the tissues. Moreover, the analysis of sequencing data in combination with clinical information has revealed the impacts of somatic mosaicism on disease processes. In this review, we discuss somatic mosaicism in various tissues and its clinical implications for human disease.

Targeting the Inflammasome in Cardiovascular Disease

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Development of cardiovascular disease and inflammation are heavily intertwined, and inflammasome activation is thought play an important role in this interaction.

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This review provides an overview of preclinical and clinical studies supporting inflammasomes as a therapeutic target in atherosclerosis and heart failure.

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Future studies exploring direct inflammasome inhibition, either NLRP3 or the lesser-studied inflammasomes, are also discussed.

The pathogenesis of cardiovascular disease (CVD) is complex and multifactorial, and inflammation plays a central role. Inflammasomes are multimeric protein complexes that are activated in a 2-step manner in response to infection or tissue damage. Upon activation the proinflammatory cytokines, interleukins-1β and -18 are released. In the last decade, the evidence that inflammasome activation plays an important role in CVD development became stronger. We discuss the role of different inflammasomes in the pathogenesis of CVD, focusing on atherosclerosis and heart failure. This review also provides an overview of existing experimental studies and clinical trials on inflammasome inhibition as a therapeutic target in these disorders.

Clonal hematopoiesis and vascular disease

Somatic mutations in hematopoietic stem cells are common with aging and can result in expansion of clones harboring mutations, termed clonal hematopoiesis. This results in an increased risk of blood cancers but has also been linked with chronic inflammatory disease states. In recent years, clonal hematopoiesis has been established to have a causative role in atherogenesis and cardiovascular disease. Additionally, as the effector cells have been identified to be immune cells, there is ongoing interest in assessing whether dysregulated immune function plays a role in other chronic inflammatory conditions such as rheumatologic disease. Here, we summarize current understanding of clonal hematopoiesis with a focus on cardiovascular disease and inflammation while outlining the potential, yet unexplored, relationship between clonal hematopoiesis and autoimmune disease. Hematopoietic stem cells (HSCs) continually regenerate blood cells. Acquisition of a somatic mutation that provides a selective advantage, a driver mutation, can result in clonal expansion. Clonal hematopoiesis of indeterminate potential, where somatic mutations in certain cancer-associated genes result in clonal expansion in the absence of overt malignancy, can result in atherosclerotic cardiovascular disease in multiple vascular beds, inflammation, and may also contribute to the pathogenesis of autoimmune disease. Many questions remain unanswered regarding the relationship between clonal hematopoiesis and inflammatory disorders.

Clonal hematopoiesis in cardiovascular disease and therapeutic implications

Clonal hematopoiesis arises from somatic mutations that provide a fitness advantage to hematopoietic stem cells and the outgrowth of clones of blood cells. Clonal hematopoiesis commonly involves mutations in genes that are involved in epigenetic modifications, signaling and DNA damage repair. Clonal hematopoiesis has emerged as a major independent risk factor in atherosclerotic cardiovascular disease, thrombosis and heart failure. Studies in mouse models of clonal hematopoiesis have shown an increase in atherosclerosis, thrombosis and heart failure, involving increased myeloid cell inflammatory responses and inflammasome activation. Although increased inflammatory responses have emerged as a common underlying principle, some recent studies indicate mutation-specific effects. The discovery of the association of clonal hematopoiesis with cardiovascular disease and the recent demonstration of benefit of anti-inflammatory treatments in human cardiovascular disease converge to suggest that anti-inflammatory treatments should be directed to individuals with clonal hematopoiesis. Such treatments could target specific inflammasomes, common downstream mediators such as IL-1β and IL-6, or mutations linked to clonal hematopoiesis.

Therapeutic strategies targeting inflammation and immunity in atherosclerosis: how to proceed?

Atherosclerosis is a chronic inflammatory disease of the arterial wall, characterized by the formation of plaques containing lipid, connective tissue and immune cells in the intima of large and medium-sized arteries. Over the past three decades, a substantial reduction in cardiovascular mortality has been achieved largely through LDL-cholesterol-lowering regimes and therapies targeting other traditional risk factors for cardiovascular disease, such as hypertension, smoking, diabetes mellitus and obesity. However, the overall benefits of targeting these risk factors have stagnated, and a huge global burden of cardiovascular disease remains. The indispensable role of immunological components in the establishment and chronicity of atherosclerosis has come to the forefront as a clinical target, with proof-of-principle studies demonstrating the benefit and challenges of targeting inflammation and the immune system in cardiovascular disease. In this Review, we provide an overview of the role of the immune system in atherosclerosis by discussing findings from preclinical research and clinical trials. We also identify important challenges that need to be addressed to advance the field and for successful clinical translation, including patient selection, identification of responders and non-responders to immunotherapies, implementation of patient immunophenotyping and potential surrogate end points for vascular inflammation. Finally, we provide strategic guidance for the translation of novel targets of immunotherapy into improvements in patient outcomes.

In this Review, the authors provide an overview of the immune cells involved in atherosclerosis, discuss preclinical research and published and ongoing clinical trials assessing the therapeutic potential of targeting the immune system in atherosclerosis, highlight emerging therapeutic targets from preclinical studies and identify challenges for successful clinical translation.

Inflammation is an important component of the pathophysiology of cardiovascular disease; an imbalance between pro-inflammatory and anti-inflammatory processes drives chronic inflammation and the formation of atherosclerotic plaques in the vessel wall.

Clinical trials assessing canakinumab and colchicine therapies in atherosclerotic cardiovascular disease have provided proof-of-principle of the benefits associated with therapeutic targeting of the immune system in atherosclerosis.

The immunosuppressive adverse effects associated with the systemic use of anti-inflammatory drugs can be minimized through targeted delivery of anti-inflammatory drugs to the atherosclerotic plaque, defining the window of opportunity for treatment and identifying more specific targets for cardiovascular inflammation.

Implementing immunophenotyping in clinical trials in patients with atherosclerotic cardiovascular disease will allow the identification of immune signatures and the selection of patients with the highest probability of deriving benefit from a specific therapy.

Clinical stratification via novel risk factors and discovery of new surrogate markers of vascular inflammation are crucial for identifying new immunotherapeutic targets and their successful translation into the clinic.

Inflammasome Activation in Myeloid Malignancies—Friend or Foe?

Myeloid malignancies including myelodysplastic syndromes, myeloproliferative neoplasms and acute myeloid leukemia are heterogeneous disorders originating from mutated hematopoietic stem and progenitor cells (HSPCs). Genetically, they are very heterogeneous and characterized by uncontrolled proliferation and/or blockage of differentiation of abnormal HSPCs. Recent studies suggest the involvement of inflammasome activation in disease initiation and clonal progression. Inflammasomes are cytosolic innate immune sensors that, upon activation, induce caspase-1 mediated processing of interleukin (IL) -1-cytokine members IL-1β and IL-18, as well as initiation of gasdermin D-dependent pyroptosis. Inflammasome activation leads to a pro-inflammatory microenvironment in the bone marrow, which drives proliferation and may induce clonal selection of mutated HSPCs. However, there are also contradictory data showing that inflammasome activation actually counteracts leukemogenesis. Overall, the beneficial or detrimental effect of inflammasome activation seems to be highly dependent on mutational, environmental, and immunological contexts and an improved understanding is fundamental to advance specific therapeutic targeting strategies. This review summarizes current knowledge about this dichotomous effect of inflammasome activation in myeloid malignancies and provides further perspectives on therapeutic targeting.

Activation and Immune Regulation Mechanisms of PYHIN Family During Microbial Infection

The innate immune system defenses against pathogen infections via patten-recognition receptors (PRRs). PRRs initiate immune responses by recognizing pathogen-associated molecular patterns (PAMPs), including peptidoglycan, lipopolysaccharide, and nucleic acids. Several nucleic acid sensors or families have been identified, such as RIG-I-like receptors (RLRs), Toll-like receptors (TLRs), cyclic GMP-AMP synthase (cGAS), and PYHIN family receptors. In recent years, the PYHIN family cytosolic DNA receptors have increased attention because of their important roles in initiating innate immune responses. The family members in humans include Absent in melanoma 2 (AIM2), IFN-γ inducible protein 16 (IFI16), interferon-inducible protein X (IFIX), and myeloid cell nuclear differentiation antigen (MNDA). The PYHIN family members are also identified in mice, including AIM2, p202, p203, p204, and p205. Herein, we summarize recent advances in understanding the activation and immune regulation mechanisms of the PYHIN family during microbial infection. Furthermore, structural characterizations of AIM2, IFI16, p202, and p204 provide more accurate insights into the signaling mechanisms of PYHIN family receptors. Overall, the molecular details will facilitate the development of reagents to defense against viral infections.

Somatic Mutations in Cardiovascular Disease

Advances in population-scale genomic sequencing have greatly expanded the understanding of the inherited basis of cardiovascular disease (CVD). Reanalysis of these genomic datasets identified an unexpected risk factor for CVD, somatically acquired DNA mutations. In this review, we provide an overview of somatic mutations and their contributions to CVD. We focus on the most common and well-described manifestation, clonal hematopoiesis of indeterminate potential. We also review the currently available data regarding how somatic mutations lead to tissue mosaicism in various forms of CVD, including atrial fibrillation and aortic aneurism associated with Marfan Syndrome. Finally, we highlight future research directions given current knowledge gaps and consider how technological advances will enhance the discovery of somatic mutations in CVD and management of patients with somatic mutations.

Addressing dyslipidemic risk beyond LDL-cholesterol

Despite the success of LDL-lowering drugs in reducing cardiovascular disease (CVD), there remains a large burden of residual disease due in part to persistent dyslipidemia characterized by elevated levels of triglyceride-rich lipoproteins (TRLs) and reduced levels of HDL. This form of dyslipidemia is increasing globally as a result of the rising prevalence of obesity and metabolic syndrome. Accumulating evidence suggests that impaired hepatic clearance of cholesterol-rich TRL remnants leads to their accumulation in arteries, promoting foam cell formation and inflammation. Low levels of HDL may associate with reduced cholesterol efflux from foam cells, aggravating atherosclerosis. While fibrates and fish oils reduce TRL, they have not been uniformly successful in reducing CVD, and there is a large unmet need for new approaches to reduce remnants and CVD. Rare genetic variants that lower triglyceride levels via activation of lipolysis and associate with reduced CVD suggest new approaches to treating dyslipidemia. Apolipoprotein C3 (APOC3) and angiopoietin-like 3 (ANGPTL3) have emerged as targets for inhibition by antibody, antisense, or RNAi approaches. Inhibition of either molecule lowers TRL but respectively raises or lowers HDL levels. Large clinical trials of such agents in patients with high CVD risk and elevated levels of TRL will be required to demonstrate efficacy of these approaches.

Aorta in Pathologies May Function as an Immune Organ by Upregulating Secretomes for Immune and Vascular Cell Activation, Differentiation and Trans-Differentiation-Early Secretomes may Serve as Drivers for Trained Immunity

To determine whether aorta becomes immune organ in pathologies, we performed transcriptomic analyses of six types of secretomic genes (SGs) in aorta and vascular cells and made the following findings: 1) 53.7% out of 21,306 human protein genes are classified into six secretomes, namely, canonical, caspase 1, caspase 4, exosome, Weibel-Palade body, and autophagy; 2) Atherosclerosis (AS), chronic kidney disease (CKD) and abdominal aortic aneurysm (AAA) modulate six secretomes in aortas; and Middle East Respiratory Syndrome Coronavirus (MERS-CoV, COVID-19 homologous) infected endothelial cells (ECs) and angiotensin-II (Ang-II) treated vascular smooth muscle cells (VSMCs) modulate six secretomes; 3) AS aortas upregulate T and B cell immune SGs; CKD aortas upregulate SGs for cardiac hypertrophy, and hepatic fibrosis; and AAA aorta upregulate SGs for neuromuscular signaling and protein catabolism; 4) Ang-II induced AAA, canonical, caspase 4, and exosome SGs have two expression peaks of high (day 7)-low (day 14)-high (day 28) patterns; 5) Elastase induced AAA aortas have more inflammatory/immune pathways than that of Ang-II induced AAA aortas; 6) Most disease-upregulated cytokines in aorta may be secreted via canonical and exosome secretomes; 7) Canonical and caspase 1 SGs play roles at early MERS-CoV infected ECs whereas caspase 4 and exosome SGs play roles in late/chronic phases; and the early upregulated canonical and caspase 1 SGs may function as drivers for trained immunity (innate immune memory); 8) Venous ECs from arteriovenous fistula (AVF) upregulate SGs in five secretomes; and 9) Increased some of 101 trained immunity genes and decreased trained tolerance regulator IRG1 participate in upregulations of SGs in atherosclerotic, Ang-II induced AAA and CKD aortas, and MERS-CoV infected ECs, but less in SGs upregulated in AVF ECs. IL-1 family cytokines, HIF1α, SET7 and mTOR, ROS regulators NRF2 and NOX2 partially regulate trained immunity genes; and NRF2 plays roles in downregulating SGs more than that of NOX2 in upregulating SGs. These results provide novel insights on the roles of aorta as immune organ in upregulating secretomes and driving immune and vascular cell differentiations in COVID-19, cardiovascular diseases, inflammations, transplantations, autoimmune diseases and cancers.

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.

NR1D1 Deletion Induces Rupture-Prone Vulnerable Plaques by Regulating Macrophage Pyroptosis via the NF-κB/NLRP3 Inflammasome Pathway

Vulnerable plaque rupture is the main trigger of most acute cardiovascular events. But the underlying mechanisms responsible for the transition from stable to vulnerable plaque remain largely unknown. Nuclear receptor subfamily 1 group D member 1 (NR1D1), also known as REV-ERB α, is a nuclear receptor that has shown the protective role in cardiovascular system. However, the effect of NR1D1 on vulnerable plaque rupture and its underlying mechanisms are still unclear. By generating the rupture-prone vulnerable plaque model in hypercholesterolemic ApoE^−/− mice and NR1D1^−/−ApoE^−/− mice, we demonstrated that NR1D1 deficiency significantly augmented plaque vulnerability/rupture, with higher incidence of intraplaque hemorrhage (78.26% vs. 47.82%, P = 0.0325) and spontaneous plaque rupture with intraluminal thrombus formation (65.21% vs. 39.13%, P = 0.1392). In vivo experiments indicated that NR1D1 exerted a protective role in the vasculature. Mechanically, NR1D1 deficiency aggravates macrophage infiltration, inflammation, and oxidative stress. Compared with the ApoE^−/− mice, NR1D1^−/−ApoE^−/− mice exhibited a significantly higher expression level of pyroptosis-related genes in macrophages within the plaque. Further investigation based on mice bone marrow-derived macrophages (BMDMs) confirmed that NR1D1 exerted a protective effect by inhibiting macrophage pyroptosis in a NLRP3-inflammasome-dependent manner. Besides, pharmacological activation of NR1D1 by SR9009, a specific NR1D1 agonist, prevented plaque vulnerability/rupture. In general, our findings provide further evidences that NR1D1 plays a protective role in the vasculature, regulates inflammation and oxidative stress, and stabilizes rupture-prone vulnerable plaques.

A Vicious Circle of Clonal Haematopoiesis of Indeterminate Potential and Cardiovascular Disease

Clonal haematopoiesis of indeterminate potential (CHIP) represents a recently identified overlap between cancer and cardiovascular disease (CVD). CHIP develops as a result of certain acquired somatic mutations that predispose to leukaemia, but clinically even more prevalent, associate with increased risk for CVD and CVD-related death. Experimental studies suggest a causal role for CHIP aggravating inflammatory processes in CVD, and recent epidemiologic and genetic studies indicate that classical CVD risk factors may increase the risk of acquiring CHIP driver mutations, thus fuelling a vicious circle. The potential mechanism underlying the associative link between CHIP and CVD and mortality has been the focus of a few recent excellent experimental and observational studies which are summarized and discussed in this concise non-systematic review article. These data support a pathomechanistic view of a spiralling vicious circle in which CHIP aggravates the inflammatory immune response in CVD, and CVD-driven elevated haematopoietic activity promotes CHIP development.

Novel Knowledge-Based Transcriptomic Profiling of Lipid Lysophosphatidylinositol-Induced Endothelial Cell Activation

To determine whether pro-inflammatory lipid lysophosphatidylinositols (LPIs) upregulate the expressions of membrane proteins for adhesion/signaling and secretory proteins in human aortic endothelial cell (HAEC) activation, we developed an EC biology knowledge-based transcriptomic formula to profile RNA-Seq data panoramically. We made the following primary findings: first, G protein-coupled receptor 55 (GPR55), the LPI receptor, is expressed in the endothelium of both human and mouse aortas, and is significantly upregulated in hyperlipidemia; second, LPIs upregulate 43 clusters of differentiation (CD) in HAECs, promoting EC activation, innate immune trans-differentiation, and immune/inflammatory responses; 72.1% of LPI-upregulated CDs are not induced in influenza virus-, MERS-CoV virus- and herpes virus-infected human endothelial cells, which hinted the specificity of LPIs in HAEC activation; third, LPIs upregulate six types of 640 secretomic genes (SGs), namely, 216 canonical SGs, 60 caspase-1-gasdermin D (GSDMD) SGs, 117 caspase-4/11-GSDMD SGs, 40 exosome SGs, 179 Human Protein Atlas (HPA)-cytokines, and 28 HPA-chemokines, which make HAECs a large secretory organ for inflammation/immune responses and other functions; fourth, LPIs activate transcriptomic remodeling by upregulating 172 transcription factors (TFs), namely, pro-inflammatory factors NR4A3, FOS, KLF3, and HIF1A; fifth, LPIs upregulate 152 nuclear DNA-encoded mitochondrial (mitoCarta) genes, which alter mitochondrial mechanisms and functions, such as mitochondrial organization, respiration, translation, and transport; sixth, LPIs activate reactive oxygen species (ROS) mechanism by upregulating 18 ROS regulators; finally, utilizing the Cytoscape software, we found that three mechanisms, namely, LPI-upregulated TFs, mitoCarta genes, and ROS regulators, are integrated to promote HAEC activation. Our results provide novel insights into aortic EC activation, formulate an EC biology knowledge-based transcriptomic profile strategy, and identify new targets for the development of therapeutics for cardiovascular diseases, inflammatory conditions, immune diseases, organ transplantation, aging, and cancers.

Oxidized Phospholipids Promote NETosis and Arterial Thrombosis in LNK(SH2B3) Deficiency

Supplemental Digital Content is available in the text.

Background:

LNK/SH2B3 inhibits Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling by hematopoietic cytokine receptors. Genome-wide association studies have shown association of a common single nucleotide polymorphism in LNK (R262W, T allele) with neutrophilia, thrombocytosis, and coronary artery disease. We have shown that LNK(TT) reduces LNK function and that LNK-deficient mice display prominent platelet–neutrophil aggregates, accelerated atherosclerosis, and thrombosis. Platelet–neutrophil interactions can promote neutrophil extracellular trap (NET) formation. The goals of this study were to assess the role of NETs in atherosclerosis and thrombosis in mice with hematopoietic Lnk deficiency.

Methods:

We bred mice with combined deficiency of Lnk and the NETosis-essential enzyme PAD4 (peptidyl arginine deiminase 4) and transplanted their bone marrow into Ldlr^–/– mice. We evaluated the role of LNK in atherothrombosis in humans and mice bearing a gain of function variant in JAK2 (JAK2^V617F).

Results:

Lnk-deficient mice displayed accelerated carotid artery thrombosis with prominent NETosis that was completely reversed by PAD4 deficiency. Thrombin-activated Lnk^–/– platelets promoted increased NETosis when incubated with Lnk^–/– neutrophils compared with wild-type platelets or wild-type neutrophils. This involved increased surface exposure and release of oxidized phospholipids (OxPL) from Lnk^–/– platelets, as well as increased priming and response of Lnk^–/– neutrophils to OxPL. To counteract the effects of OxPL, we introduced a transgene expressing the single-chain variable fragment of E06 (E06-scFv). E06-scFv reversed accelerated NETosis, atherosclerosis, and thrombosis in Lnk^–/– mice. We also showed increased NETosis when human induced pluripotent stem cell–derived LNK(TT) neutrophils were incubated with LNK(TT) platelet/megakaryocytes, but not in isogenic LNK(CC) controls, confirming human relevance. Using data from the UK Biobank, we found that individuals with the JAK2^VF mutation only showed increased risk of coronary artery disease when also carrying the LNK R262W allele. Mice with hematopoietic Lnk^+/– and Jak2^VF clonal hematopoiesis showed accelerated arterial thrombosis but not atherosclerosis compared with Jak2^VFLnk^+/+ controls.

Conclusions:

Hematopoietic Lnk deficiency promotes NETosis and arterial thrombosis in an OxPL-dependent fashion. LNK(R262W) reduces LNK function in human platelets and neutrophils, promoting NETosis, and increases coronary artery disease risk in humans carrying Jak2^VF mutations. Therapies targeting OxPL may be beneficial for coronary artery disease in genetically defined human populations.

Development and Validation of a Pyroptosis-Related Long Non-coding RNA Signature for Hepatocellular Carcinoma

Background: Hepatocellular carcinoma (HCC) is a highly aggressive malignant disease, and numerous studies have demonstrated that an inflammatory environment can induce normal cells to transform into cancerous.

Methods: We integrated genomic data to comprehensively assess the association between pyroptosis and tumor microenvironment (TME) cell-infiltrating characteristics in HCC, as well as the potential molecular function and clinical significance of lncRNA.

Results: The analysis of CNV alteration frequency displayed that CNV changes were common in 33 PRGs, and most were focused on copy number amplification. As a result of lasso regression analysis, nine differentially expressed lncRNAs (AL031985.3, NRAV, OSMR-AS1, AC073611.1, MKLN1-AS, AL137186.2, AL049840.4, MIR4435-2HG, and AL118511.1) were selected as independent prognosis factors of HCC patients. Patients at high risk have poorer survival than those in the low-risk group in training and testing cohorts. A low-risk score was significantly associated with an IC50 of chemotherapeutics such as bortezomib (p < 0.001), but a high-risk score was significantly linked to docetaxel (p < 0.001), implying that signature served as a prospective predictor for chemosensitivity.

Conclusion: This work suggests pyroptosis-related lncRNAs features and their potential mechanisms on tumor microenvironment. The exploration may assist in identifying novel biomarkers and assist patients in predicting their prognosis, clinical diagnosis, and management.

Clonal hematopoiesis of indeterminate potential (CHIP): Linking somatic mutations, hematopoiesis, chronic inflammation and cardiovascular disease

Clonal hematopoiesis of indeterminate potential (CHIP) is the presence of a clonally expanded hematopoietic stem cell caused by a leukemogenic mutation in individuals without evidence of hematologic malignancy, dysplasia, or cytopenia. CHIP is associated with a 0.5-1.0% risk per year of leukemia. Remarkably, it confers a two-fold increase in cardiovascular risk independent of traditional risk factors. Roughly 80% of patients with CHIP have mutations in epigenetic regulators DNMT3A, TET2, ASXL1, DNA damage repair genes PPM1D, TP53, the regulatory tyrosine kinase JAK2, or mRNA spliceosome components SF3B1, and SRSF2. CHIP is associated with a pro-inflammatory state that has been linked to coronary artery disease, myocardial infarction, and venous thromboembolic disease, as well as prognosis among those with aortic stenosis and heart failure. Heritable and acquired risk factors are associated with increased CHIP prevalence, including germline variation, age, unhealthy lifestyle behaviors (i.e. smoking, obesity), inflammatory conditions, premature menopause, HIV and exposure to cancer therapies. This review aims to summarize emerging research on CHIP, the mechanisms underlying its important role in propagating inflammation and accelerating cardiovascular disease, and new studies detailing the role of associated risk factors and co-morbidities that increase CHIP prevalence.

Roles of Macrophages in Atherogenesis

Atherosclerosis is a chronic inflammatory disease that may ultimately lead to local proteolysis, plaque rupture, and thrombotic vascular disease, resulting in myocardial infarction, stroke, and sudden cardiac death. Circulating monocytes are recruited to the arterial wall in response to inflammatory insults and differentiate into macrophages which make a critical contribution to tissue damage, wound healing, and also regression of atherosclerotic lesions. Within plaques, macrophages take up aggregated lipoproteins which have entered the vessel wall to give rise to cholesterol-engorged foam cells. Also, the macrophage phenotype is influenced by various stimuli which affect their polarization, efferocytosis, proliferation, and apoptosis. The heterogeneity of macrophages in lesions has recently been addressed by single-cell sequencing techniques. This article reviews recent advances regarding the roles of macrophages in different stages of disease pathogenesis from initiation to advanced atherosclerosis. Macrophage-based therapies for atherosclerosis management are also described.

Dying cells fan the flames of inflammation

[Figure: see text].