Pathogen-sensing plasmacytoid dendritic cells stimulate cytotoxic T-cell function in the atherosclerotic plaque through interferon-alpha

Mechanistic insight: Linking cardiovascular complications of inflammatory bowel disease

Cardiovascular diseases (CVD) are the leading cause of mortality worldwide despite an aggressive reduction of traditional cardiovascular risk factors. Underlying inflammatory conditions such as inflammatory bowel disease (IBD) increase the risk of developing CVD. A broad understanding of the underlying pathophysiological processes between IBD and CVD is required to treat and prevent cardiovascular events in patients with IBD. This review highlights the commonality between IBD and CVD, including dysregulated immune response, genetics, environmental risk factors, altered gut microbiome, stress, endothelial dysfunction and abnormalities, to shed light on an essential area of modern medicine.

Aortic Cellular Heterogeneity in Health and Disease: Novel Insights Into Aortic Diseases From Single-Cell RNA Transcriptomic Data Sets

Aortic diseases such as atherosclerosis, aortic aneurysms, and aortic stiffening are significant complications that can have significant impact on end-stage cardiovascular disease. With limited pharmacological therapeutic strategies that target the structural changes in the aorta, surgical intervention remains the only option for some patients with these diseases. Although there have been significant contributions to our understanding of the cellular architecture of the diseased aorta, particularly in the context of atherosclerosis, furthering our insight into the cellular drivers of disease is required. The major cell types of the aorta are well defined; however, the advent of single-cell RNA sequencing provides unrivaled insights into the cellular heterogeneity of each aortic cell type and the inferred biological processes associated with each cell in health and disease. This review discusses previous concepts that have now been enhanced with recent advances made by single-cell RNA sequencing with a focus on aortic cellular heterogeneity.

The Evolving Role of Dendritic Cells in Atherosclerosis

Atherosclerosis, a major contributor to cardiovascular morbidity and mortality, is characterized by chronic inflammation of the arterial wall. This inflammatory process is initiated and maintained by both innate and adaptive immunity. Dendritic cells (DCs), which are antigen-presenting cells, play a crucial role in the development of atherosclerosis and consist of various subtypes with distinct functional abilities. Following the recognition and binding of antigens, DCs become potent activators of cellular responses, bridging the innate and adaptive immune systems. The modulation of specific DC subpopulations can have either pro-atherogenic or atheroprotective effects, highlighting the dual pro-inflammatory or tolerogenic roles of DCs. In this work, we provide a comprehensive overview of the evolving roles of DCs and their subtypes in the promotion or limitation of atherosclerosis development. Additionally, we explore antigen pulsing and pharmacological approaches to modulate the function of DCs in the context of atherosclerosis.

Alterations in Th17 Cells and Non-Classical Monocytes as a Signature of Subclinical Coronary Artery Atherosclerosis during ART-Treated HIV-1 Infection

Cardiovascular disease (CVD) remains an important comorbidity in people living with HIV-1 (PLWH) receiving antiretroviral therapy (ART). Our previous studies performed in the Canadian HIV/Aging Cohort Study (CHACS) (>40 years-old; Framingham Risk Score (FRS) > 5%) revealed a 2-3-fold increase in non-calcified coronary artery atherosclerosis (CAA) plaque burden, measured by computed tomography angiography scan (CTAScan) as the total (TPV) and low attenuated plaque volume (LAPV), in ART-treated PLWH (HIV+) versus uninfected controls (HIV-). In an effort to identify novel correlates of subclinical CAA, markers of intestinal damage (sCD14, LBP, FABP2); cell trafficking/inflammation (CCL20, CX3CL1, MIF, CCL25); subsets of Th17-polarized and regulatory (Tregs) CD4+ T-cells, classical/intermediate/non-classical monocytes, and myeloid/plasmacytoid dendritic cells were studied in relationship with HIV and TPV/LAPV status. The TPV detection/values coincided with higher plasma sCD14, FABP2, CCL20, MIF, CX3CL1, and triglyceride levels; lower Th17/Treg ratios; and classical monocyte expansion. Among HIV+, TPV+ versus TPV- exhibited lower Th17 frequencies, reduced Th17/Treg ratios, higher frequencies of non-classical CCR9lowHLADRhigh monocytes, and increased plasma fibrinogen levels. Finally, Th17/Treg ratios and non-classical CCR9lowHLADRhigh monocyte frequencies remained associated with TPV/LAPV after adjusting for FRS and HIV/ART duration in a logistic regression model. These findings point to Th17 paucity and non-classical monocyte abundance as novel immunological correlates of subclinical CAA that may fuel the CVD risk in ART-treated PLWH.

A Blood Immunological Signature of Subclinical Coronary Artery Atherosclerosis in People Living with HIV-1 Receiving Antiretroviral Therapy

Cardiovascular disease (CVD) remains an important co-morbidity in people living with HIV-1 (PLWH) receiving antiretroviral therapy (ART). Our previous studies performed on the Canadian HIV/Aging Cohort Study (CHACS) (>40 years-old; Framingham Risk Score (FRS) >5%), revealed a 2-3-fold increase in non-calcified coronary artery atherosclerosis (CAA) plaque burden, measured by Computed tomography angiography scan (CTAScan) as total (TPV) and low attenuated plaque volume (LAPV) in ART-treated PLWH (HIV+) versus uninfected controls (HIV-). In an effort to identify novel correlates of subclinical CAA, markers of intestinal damage (sCD14, LBP, FABP2); cell trafficking/inflammation (CCL20, CX3CL1, MIF, CCL25); subsets of Th17-polarized and regulatory (Tregs) CD4 + T-cells, classical/intermediate/non-classical monocytes, and myeloid/plasmacytoid dendritic cells, were studied in relationship with HIV and TPV/LAPV status. The TPV detection/values coincided with higher plasma sCD14, FABP2, CCL20, MIF, CX3CL1 and triglyceride levels, lower Th17/Treg ratios, and classical monocyte expansion. Among HIV + , TPV + versus TPV - exhibited lower Th17 frequencies, reduced Th17/Treg ratios, higher frequencies of non-classical CCR9 low HLADR high monocyte, and increased plasma fibrinogen levels. Finally, Th17/Treg ratios and non-classical CCR9 low HLADR high monocyte frequencies remained associated with TPV/LAPV after adjusting for FRS and HIV/ART duration in a logistic regression model. These findings point to Th17 paucity and non-classical monocyte abundance as novel immunological correlates of subclinical CAA that may fuel the CVD risk in ART-treated PLWH.

Fat and inflammation: adipocyte-myeloid cell crosstalk in atherosclerosis

Adipose tissue inflammation has been implicated in various chronic inflammatory diseases and cancer. Perivascular adipose tissue (PVAT) surrounds the aorta as an extra layer and was suggested to contribute to atherosclerosis development. PVAT regulates the function of endothelial and vascular smooth muscle cells in the aorta and represent a reservoir for various immune cells which may participate in aortic inflammation. Recent studies demonstrate that adipocytes also express various cytokine receptors and, therefore, may directly respond to inflammatory stimuli. Here we will summarize current knowledge on immune mechanisms regulating adipocyte activation and the crosstalk between myeloid cells and adipocytes in pathogenesis of atherosclerosis.

Cytokines and their role in cardiovascular diseases

The evaluation of diagnostic and prognostic biomarkers has always been a hot topic in various diseases. Considering that cardiovascular diseases (CVDs) have the highest mortality and morbidity rates in the world, various studies have been conducted so far to find CVD associated biomarkers, including cardiac troponin (cTn) and NT-proBNP. Cytokines are components of the immune system that are involved in the pathogenesis of CVD due to their contribution to the inflammation process. The level of cytokines varies in many cardiovascular diseases. For instance, the plasma level of IL-1α, IL-18, IL-33, IL-6 and IL-8 is positively correlated with atherosclerosis and that of some other interleukins such as IL-35 is negatively correlated with acute myocardial infarction or cardiac angina. Due to its pivotal role in the inflammation process, IL-1 super family is involved in many CVDs, including atherosclerosis. IL-20 among the interleukins of IL-10 family has a pro-atherogenic role, while others, such as IL-10 and IL-19, play an anti-atherogenic role. In the present review, we have collected the latest published evidence in this respect to discuss valuable cytokines from the diagnostic and prognostic stand point in CVDs.

Five-year cardiovascular event risk in early rheumatoid arthritis patients who received treat-to-target management: a case-control study

OBJECTIVES

This study explored whether the excess cardiovascular (CV) disease (CVD) risk in RA could be ameliorated by suppression of inflammation using a treat-to-target (T2T) approach. We compared the CV event (CVE) incidence among ERA patients managed by a T2T strategy with a CV risk factor-matched non-RA population and a historical RA cohort (HRA).

METHODS

This was an observational study using the city-wide hospital data and the ERA registry. ERA patients received T2T management while HRA patients received routine care. Each ERA/HRA patient was matched to three non-RA controls according to age, gender and CV risk factors. Patients on antiplatelet/anticoagulant agents, with pre-existing CVD, chronic kidney disease or other autoimmune diseases were excluded. All subjects were followed for up to 5 years. The primary end point was the first occurrence of a CVE.

RESULTS

The incidence of CVE in the ERA cohort (n = 261) and ERA controls were similar with a hazard ratio of 0.53 (95% CI 0.15, 1.79). In contrast, the incidence of CVE in the HRA cohort (n = 268) was significantly higher than that of the HRA controls with a hazard ratio of 1.9 (95% CI 1.16, 3.13). The incidence of CVE in the ERA cohort was significantly lower than that of the HRA cohort and the difference became insignificant after adjusting for inflammation, the use of methotrexate and traditional CV risk factors.

CONCLUSION

ERA patients managed by a T2T strategy did not develop excess CVE compared with CV risk factor-matched controls over 5 years.

Toll-Like Receptor 3 Mediates Aortic Stenosis Through a Conserved Mechanism of Calcification

BACKGROUND

Calcific aortic valve disease (CAVD) is characterized by a phenotypic switch of valvular interstitial cells to bone-forming cells. Toll-like receptors (TLRs) are evolutionarily conserved pattern recognition receptors at the interface between innate immunity and tissue repair. Type I interferons (IFNs) are not only crucial for an adequate antiviral response but also implicated in bone formation. We hypothesized that the accumulation of endogenous TLR3 ligands in the valvular leaflets may promote the generation of osteoblast-like cells through enhanced type I IFN signaling.

METHODS

Human valvular interstitial cells isolated from aortic valves were challenged with mechanical strain or synthetic TLR3 agonists and analyzed for bone formation, gene expression profiles, and IFN signaling pathways. Different inhibitors were used to delineate the engaged signaling pathways. Moreover, we screened a variety of potential lipids and proteoglycans known to accumulate in CAVD lesions as potential TLR3 ligands. Ligand-receptor interactions were characterized by in silico modeling and verified through immunoprecipitation experiments. Biglycan (Bgn), Tlr3, and IFN-α/β receptor alpha chain (Ifnar1)-deficient mice and a specific zebrafish model were used to study the implication of the biglycan (BGN)-TLR3-IFN axis in both CAVD and bone formation in vivo. Two large-scale cohorts (GERA [Genetic Epidemiology Research on Adult Health and Aging], n=55 192 with 3469 aortic stenosis cases; UK Biobank, n=257 231 with 2213 aortic stenosis cases) were examined for genetic variation at genes implicated in BGN-TLR3-IFN signaling associating with CAVD in humans.

RESULTS

Here, we identify TLR3 as a central molecular regulator of calcification in valvular interstitial cells and unravel BGN as a new endogenous agonist of TLR3. Posttranslational BGN maturation by xylosyltransferase 1 (XYLT1) is required for TLR3 activation. Moreover, BGN induces the transdifferentiation of valvular interstitial cells into bone-forming osteoblasts through the TLR3-dependent induction of type I IFNs. It is intriguing that Bgn-/-, Tlr3-/-, and Ifnar1-/- mice are protected against CAVD and display impaired bone formation. Meta-analysis of 2 large-scale cohorts with >300 000 individuals reveals that genetic variation at loci relevant to the XYLT1-BGN-TLR3-interferon-α/β receptor alpha chain (IFNAR) 1 pathway is associated with CAVD in humans.

CONCLUSIONS

This study identifies the BGN-TLR3-IFNAR1 axis as an evolutionarily conserved pathway governing calcification of the aortic valve and reveals a potential therapeutic target to prevent CAVD.

Diagnostic model constructed by nine inflammation-related genes for diagnosing ischemic stroke and reflecting the condition of immune-related cells

Background

Ischemic cerebral infarction is the most common type of stroke with high rates of mortality, disability, and recurrence. However, the known diagnostic biomarkers and therapeutic targets for ischemic stroke (IS) are limited. In the current study, we aimed to identify novel inflammation-related biomarkers for IS using machine learning analysis and to explore their relationship with the levels of immune-related cells in whole blood samples.

Methods

Gene expression profiles of healthy controls and patients with IS were download from the Gene Expression Omnibus. Analysis of differentially expressed genes (DEGs) was performed in healthy controls and patients with IS. Single-sample gene set enrichment analysis was performed to calculate inflammation scores, and weighted gene co-expression network analysis was used to analyze genes in significant modules associated with inflammation scores. Key DEGs in significant modules were then analyzed using LASSO regression analysis for constructing a diagnostic model. The effectiveness and specificity of the diagnostic model was verified in healthy controls and patients with IS and with cerebral hemorrhage (CH) using qRT-PCR. The relationship between diagnostic score and the levels of immune-related cells in whole blood were analyzed using Pearson correlations.

Results

A total of 831 DEGs were identified. Both chronic and acute inflammation scores were higher in patients with IS, while 54 DEGs were also clustered in the gene modules associated with chronic and acute inflammation scores. Among them, a total of 9 genes were selected to construct a diagnostic model. Interestingly, RT-qPCR showed that the diagnostic model had better diagnostic value for IS but not for CH. The levels of lymphocytes were lower in blood of patients with IS, while the levels of monocytes and neutrophils were increased. The diagnostic score of the model was negatively associated with the levels of lymphocytes and positively associated with levels of monocytes and neutrophils.

Conclusions

Taken together, the diagnostic model constructed using the inflammation-related genes TNFSF10, ID1, PAQR8, OSR2, PDK4, PEX11B, TNIP1, FFAR2, and JUN exhibited high and specific diagnostic value for IS and reflected the condition of lymphocytes, monocytes, and neutrophils in the blood. The diagnostic model may contribute to the diagnosis of IS.

Expanding role of deoxyribonucleic acid-sensing mechanism in the development of lifestyle-related diseases

In lifestyle-related diseases, such as cardiovascular, metabolic, respiratory, and kidney diseases, chronic inflammation plays a causal role in their pathogenesis; however, underlying mechanisms of sterile chronic inflammation are not well-understood. Previous studies have confirmed the damage of cells in these organs in the presence of various risk factors such as diabetes, dyslipidemia, and cigarette smoking, releasing various endogenous ligands for pattern recognition receptors. These studies suggested that nucleic acids released from damaged tissues accumulate in these tissues, acting as an endogenous ligand. Undamaged DNA is an integral factor for the sustenance of life, whereas, DNA fragments, especially those from pathogens, are potent activators of the inflammatory response. Recent studies have indicated that inflammatory responses such as the production of type I interferon (IFN) induced by DNA-sensing mechanisms which contributes to self-defense system in innate immunity participates in the progression of inflammatory diseases by the recognition of nucleic acids derived from the host, including mitochondrial DNA (mtDNA). The body possesses several types of DNA sensors. Toll-like receptor 9 (TLR9) recognizes DNA fragments in the endosomes. In addition, the binding of DNA fragments in the cytosol activates cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase (cGAS), resulting in the synthesis of the second messenger cyclic GMP-AMP (cGAMP). The binding of cGAMP to stimulator of interferon genes (STING) activates NF-κB and TBK-1 signaling and consequently the production of many inflammatory cytokines including IFNs. Numerous previous studies have demonstrated the role of DNA sensors in self-defense through the recognition of DNA fragments derived from pathogens. Beyond the canonical role of TLR9 and cGAS-STING, this review describes the role of these DNA-sensing mechanism in the inflammatory responses caused by endogenous DNA fragments, and in the pathogenesis of lifestyle-related diseases.

Increased Risk of Acute Coronary Syndrome in Ankylosing Spondylitis Patients With Uveitis: A Population-Based Cohort Study

Background

Uveitis, a sight-threatening ocular inflammatory state, is associated with autoimmune diseases and systemic inflammation. This prolonged systemic inflammation may cause plaque formation in coronary arteries, subsequently resulting in acute coronary syndrome (ACS).

Methods

This retrospective, population-based study (15-year period) used the Longitudinal Health Insurance Database based on the National Health Insurance Research Database in Taiwan. Chi-square and Student's t-tests were used to examine differences between the study and comparison cohorts for categorical and continuous variables, respectively. Fine and Gray's competing risk model was used to determine the hazard ratio of the risk of ACS. Furthermore, the cumulative risk of ACS was determined using Kaplan-Meier analysis.

Results

A total of 1,111 patients with AS and uveitis were enrolled in this study cohort, and 4,444 patients with AS without uveitis were enrolled in the comparison cohort. After adjustment for age, sex, and comorbidities, patients with AS and uveitis demonstrated an increased risk of ACS compared to those without uveitis (adjusted hazard ratio: 1.675, p<0.001). In addition, Kaplan-Meier analysis revealed that patients with AS and uveitis had a significantly higher risk of ACS than those without uveitis (p<0.001). Age, diabetes mellitus, hypertension, hyperlipidemia, chronic obstructive pulmonary disease, asthma, and systemic steroids were significant risk factors for ACS. Both anterior uveitis and posterior segment involvement were associated with an increased risk of ACS in patients with AS. All-cause mortality was higher in the uveitis group (9.81%) than in the non-uveitis group (8.10%) (p=0.015).

Conclusion

Our analysis revealed that uveitis could potentially be a predictor of ACS in patients with AS. However, further prospective controlled studies are required to assess the association between uveitis and ACS in patients with AS.

CD8+ T-Cells in Juvenile-Onset SLE: From Pathogenesis to Comorbidities

Diagnosis of systemic lupus erythematosus (SLE) in childhood [juvenile-onset (J) SLE], results in a more severe disease phenotype including major organ involvement, increased organ damage, cardiovascular disease risk and mortality compared to adult-onset SLE. Investigating early disease course in these younger JSLE patients could allow for timely intervention to improve long-term prognosis. However, precise mechanisms of pathogenesis are yet to be elucidated. Recently, CD8+ T-cells have emerged as a key pathogenic immune subset in JSLE, which are increased in patients compared to healthy individuals and associated with more active disease and organ involvement over time. CD8+ T-cell subsets have also been used to predict disease prognosis in adult-onset SLE, supporting the importance of studying this cell population in SLE across age. Recently, single-cell approaches have allowed for more detailed analysis of immune subsets in JSLE, where type-I IFN-signatures have been identified in CD8+ T-cells expressing high levels of granzyme K. In addition, JSLE patients with an increased cardiometabolic risk have increased CD8+ T-cells with elevated type-I IFN-signaling, activation and apoptotic pathways associated with atherosclerosis. Here we review the current evidence surrounding CD8+ T-cell dysregulation in JSLE and therapeutic strategies that could be used to reduce CD8+ T-cell inflammation to improve disease prognosis.

Identification of Biomarkers of Autophagy-Related Genes Between Early and Advanced Carotid Atherosclerosis

Background

Accumulating evidence demonstrates that autophagy is important in inhibiting inflammation and cholesterol efflux. It suggested the autophagy may be a treatment of atherosclerosis. Thus, we screened autophagy-related mRNA to explore their mechanism of scientific basis for early diagnosis and therapy of atherosclerosis.

Methods

The GSE28829 datasets were assessed to analyze differentially expressed genes by GEO2R. And autophagy-related hub genes were identified by HADb. The biological function of autophagy-related DEmRNAs was examined by Metascape. The construction of a protein–protein network was explored by String. Cytohubba was utilized to screen hub genes. Analysis of DEmiRNA-mRNA pairs was executed by DIANA microT-CDS database. Finally, correlation analysis was carried out to identify the relationship between DEARGs and clinical and prognostic factors.

Results

A number of 1087 DEGs and 19 autophagy-related DEmRNAs were identified in advanced carotid atherosclerotic plaque compared with the early. The biological function containing development and growth was enriched. Moreover, we screened the top hub nodes with the highest degrees. MicroRNAs (miRNAs) are confirmed to participate in genesis and progression of atherosclerosis, so we further analyzed the miRNA–mRNA regulatory network genes with four hub genes to explore their potential mechanism in atherosclerosis. Then, we revealed co-expression of four key genes CTSB, ITGB1, CXCR4, TNFSF10 and autophagy-related genes. As for the clinical factors, hypertension factor showed higher expression of ITGB1. The probability of coronary heart disease factor was significantly increased with high expression of CTSB and CXCR4, as well as low expression of ITGB1 and TNFSF10. Diabetes factor tended to express distinguished levels of CTSB and ITGB1. TNFSF10 was highly expressed in both hyperlipidemia and ischemic stroke factor.

Conclusion

CTSB, ITGB1, CXCR4 and TNFSF10 may be critical in atherosclerosis development and were thought to be potential diagnostic biomarkers for atherosclerosis.

T-Cell Aging-Associated Phenotypes in Autoimmune Disease

The aging process causes profound restructuring of the host immune system, typically associated with declining host protection against cancer and infection. In the case of T cells, aging leads to the accumulation of a diverse set of T-cell aging-associated phenotypes (TASP), some of which have been implicated in driving tissue inflammation in autoimmune diseases. T cell aging as a risk determinant for autoimmunity is exemplified in two classical autoimmune conditions: rheumatoid arthritis (RA), a disease predominantly affecting postmenopausal women, and giant cell arteritis (GCA), an inflammatory vasculopathy exclusively occurring during the 6th-9th decade of life. Pathogenic T cells in RA emerge as a consequence of premature immune aging. They have shortening and fragility of telomeric DNA ends and instability of mitochondrial DNA. As a result, they produce a distinct profile of metabolites, disproportionally expand their endoplasmic reticulum (ER) membranes and release excess amounts of pro-inflammatory effector cytokines. Characteristically, they are tissue invasive, activate the inflammasome and die a pyroptotic death. Patients with GCA expand pathogenic CD4⁺ T cells due to aberrant expression of the co-stimulatory receptor NOTCH1 and the failure of the PD-1/PD-L1 immune checkpoint. In addition, GCA patients lose anti-inflammatory Treg cells, promoting tissue-destructive granulomatous vasculitis. In summary, emerging data identify T cell aging as a risk factor for autoimmune disease and directly link TASPs to the breakdown of T cell tolerance and T-cell-induced tissue inflammation.

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.

Premature coronary artery disease in patients with immune-mediated inflammatory disease: a population-based study

Background

The associations between premature atherosclerosis and immune-mediated inflammatory diseases (IMIDs) are not fully investigated. To determine whether IMIDs are associated with premature atherosclerosis, we examined the risk of incident coronary artery disease (CAD) in men less than 45 years old and women less than 50 years old with various forms of IMIDs compared with general population.

Methods

A population-based cohort was established and included patients with IMID, who were followed until the development of CAD, withdrawal from the insurance system, death, or 31 December 2016, whichever point came first. Patients with IMID included rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), primary Sjogren’s syndrome (SjS), idiopathic inflammatory myositis, systemic sclerosis (SSc), Behcet’s disease (BD), and systemic vasculitis (SV). The comparison group was 1 000 000 beneficiaries sampled at random from the whole population as matched control participants. The Kaplan-Meier method was used to compare the cumulative incidences of CAD in patients with and without IMID.

Results

Among 58 862 patients with IMID, 2139 (3.6%) developed CAD and 346 (1.3%) developed premature CAD. Relative to the comparison cohorts, the adjusted HRs for premature CAD were 1.43 (95% CI 1.09 to 1.86) for primary SjS, 2.85 (95% CI 2.63 to 3.43) for SLE, 3.18 (95% CI 1.99 to 5.09) for SSc and 2.27 (95% CI 1.01 to 5.07) for SV.

Conclusions

Primary Sjogren’s syndrome, SLE, SSc and SV are associated with an increased risk of premature CAD. Our findings will support essential efforts to improve awareness of IMID impacting young adults.

Immunotherapeutic Strategies in Cancer and Atherosclerosis-Two Sides of the Same Coin

The development and clinical approval of immunotherapies has revolutionized cancer therapy. Although the role of adaptive immunity in atherogenesis is now well-established and several immunomodulatory strategies have proven beneficial in preclinical studies, anti-atherosclerotic immunotherapies available for clinical application are not available. Considering that adaptive immune responses are critically involved in both carcinogenesis and atherogenesis, immunotherapeutic approaches for the treatment of cancer and atherosclerosis may exert undesirable but also desirable side effects on the other condition, respectively. For example, the high antineoplastic efficacy of immune checkpoint inhibitors, which enhance effector immune responses against tumor cells by blocking co-inhibitory molecules, was recently shown to be constrained by substantial proatherogenic properties. In this review, we outline the specific role of immune responses in the development of cancer and atherosclerosis. Furthermore, we delineate how current cancer immunotherapies affect atherogenesis and discuss whether anti-atherosclerotic immunotherapies may similarly have an impact on carcinogenesis.

Immune system and atherosclerosis: Hostile or friendly relationship

Coronary artery disease has remained a major health challenge despite enormous progress in prevention, diagnosis, and treatment strategies. Formation of atherosclerotic plaque is a chronic process that is developmentally influenced by intrinsic and extrinsic determinants. Inflammation triggers atherosclerosis, and the fundamental element of inflammation is the immune system. The immune system involves in the atherosclerosis process by a variety of immune cells and a cocktail of mediators. It is believed that almost all main components of this system possess a profound contribution to the atherosclerosis. However, they play contradictory roles, either protective or progressive, in different stages of atherosclerosis progression. It is evident that monocytes are the first immune cells appeared in the atherosclerotic lesion. With the plaque growth, other types of the immune cells such as mast cells, and T lymphocytes are gradually involved. Each cell releases several cytokines which cause the recruitment of other immune cells to the lesion site. This is followed by affecting the expression of other cytokines as well as altering certain signaling pathways. All in all, a mix of intertwined interactions determine the final outcome in terms of mild or severe manifestations, either clinical or subclinical. Therefore, it is of utmost importance to precisely understand the kind and degree of contribution which is made by each immune component in order to stop the growing burden of cardiovascular morbidity and mortality. In this review, we present a comprehensive appraisal on the role of immune cells in the atherosclerosis initiation and development.

Dendritic Cells and Antiphospholipid Syndrome: An Updated Systematic Review

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by autoreactive B and T cells against β2-glycoprotein I (B2GPI), with vascular thrombosis or obstetrical complications. Dendritic cells (DCs) are crucial in the generation of autoimmunity. Here, we conducted a comprehensive systematic review on the relationship between DC and APS. We performed a literature search of PubMed as of 26 March 2021. A total of 33 articles were extracted. DCs are pivotal in inducing inflammatory responses and orchestrating adaptive immunity. DCs contribute to the local inflammation regarding vascular thrombosis or obstetrical complications. Both B2GPI and antiphospholipid antibodies (aPL) can promote antigen presentation by DCs and the generation or maintenance of autoimmunity. In addition, plasmacytoid DC activation is enhanced by aPL, thereby augmenting the inflammatory response. In line with these findings, DC modulation appears promising as a future treatment for APS. In conclusion, our review indicated the crucial role of DCs in the pathogenesis of APS. Deeper understanding of the complex relationship would help in developing new treatment strategies.

Exosomes in Atherosclerosis, a Double-Edged Sword: Their Role in Disease Pathogenesis and Their Potential as Novel Therapeutics

Cardiovascular disease (CAD) due to atherosclerosis is a major cause of death worldwide. The development of atherosclerosis involves intercellular communication facilitated by exosomes secreted from vascular endothelial cells (VECs), vascular smooth muscle cells (VSMCs), immune cells, and platelets. In this review, we summarize the current understanding of exosome biogenesis and uptake, and discuss atherogenic and atheroprotective functions of exosomes secreted from these cell types. In addition, we examine the potential of enhancing the therapeutic and targeting ability of exosomes exhibiting atheroprotective function by drug loading and surface modification with targeting ligands. We conclude with current challenges associated with exosome engineering for therapeutic use.

Oxidative stress-responsive apoptosis-inducing protein in patients with heterozygous familial hypercholesterolemia

Oxidative stress, an inducer of apoptosis, plays a critical role in ischemia/reperfusion injury and atherosclerosis. We previously identified an apoptosis-inducing ligand, the post-translationally modified secreted form of eukaryotic translation initiation factor 5A (eIF5A), 'oxidative stress-responsive apoptosis-inducing protein' (ORAIP). In this study, we investigated the role of ORAIP in patients with heterozygous familial hypercholesterolemia (HeFH), a leading cause of premature cardiovascular disease. We analyzed plasma ORAIP and oxidized low-density lipoprotein (oxLDL) levels in 60 patients with HeFH (60% male, 57.0 ± 13.6 years of age) and 20 patients with LDL-C hypercholesterolemia (DL, 85% male, 64.1 ± 13.3 years of age). The coronary artery atherosclerosis from the patients with HeFH who had a coronary artery bypass graft was investigated by double immunostaining. The plasma ORAIP levels in the patients with HeFH were significantly elevated compared to those in the patients with DL (73.5 ± 46.0 vs. 48.3 ± 21.4 ng/mL, p = 0.0277). The plasma oxLDL levels in HeFH patients were also elevated (156.8 ± 65.2 vs. 123.7 ± 46.6 mg/dL, p = 0.0461) compared to those in DL patients and correlated with maxLDL-C levels (R = 0.4454, p = 0.00648). Double-immunostaining of ORAIP and oxLDL in the coronary artery from patients with HeFH who had a coronary artery bypass graft showed that ORAIP and oxLDL were colocalized with apoptotic vascular smooth muscle cells in the atherosclerotic plaque. ORAIP plays a role in the development of oxidative stress-induced atherosclerosis and may be an important therapeutic target for plaque rupture in patients with HeFH.

A myriad of roles of dendritic cells in atherosclerosis

Atherosclerosis is an inflammatory disease with break-down of homeostatic immune regulation of vascular tissues. As a critical initiator of host immunity, dendritic cells (DCs) have also been identified in the aorta of healthy individuals and atherosclerotic patients, whose roles in regulating arterial inflammation aroused great interest. Accumulating evidence has now pointed to the fundamental roles for DCs in every developmental stage of atherosclerosis due to their myriad of functions in immunity and tolerance induction, ranging from lipid uptake, efferocytosis and antigen presentation to pro- and anti-inflammatory cytokine or chemokine secretion. In this study we provide a timely summary of the published works in this field, and comprehensively discuss both the direct and indirect roles of DCs in atherogenesis. Understanding the pathogenic roles of DCs during the development of atherosclerosis in vascular tissues would certainly help to open therapeutic avenue to the treatment of cardiovascular diseases.

Ratiometric Semiconducting Polymer Nanoparticle for Reliable Photoacoustic Imaging of Pneumonia-Induced Vulnerable Atherosclerotic Plaque in Vivo

Acute pneumonia can greatly increase the vulnerable risk of atherosclerotic plaque and contribute to the mortality of cardiovascular disease. To accurately assess the rupture risk caused by acute pneumonia, we developed a novel kind of ratiometric semiconducting polymer nanoparticle (RSPN) for photoacoustic imaging of vulnerable plaque in apolipoprotein E-deficient mice complicated with pneumonia. Specifically, RSPN can react with O₂^•- and exhibit the enhanced photoacoustic signals at about 690 nm, while 800 nm is regarded as an internal photoacoustic reference. As a result, RSPN can provide reliable determination of O₂^•- within aortic atherosclerosis by analyzing the ratios of photoacoustic signals, which can successfully reflect the oxidative stress level in vulnerable plaque. Therefore, RSPN enable to specifically distinguish plaque-bearing mice and plaque-bearing mice complicated with pneumonia from healthy mice, which provides a promising tool to predict the vulnerability of plaque for reducing the mortality of atherosclerotic-induced cardiovascular disease.

Current Understanding of the Immunomodulatory Activities of High-Density Lipoproteins

Lipoproteins interact with immune cells, macrophages and endothelial cells - key players of the innate and adaptive immune system. High-density lipoprotein (HDL) particles seem to have evolved as part of the innate immune system since certain HDL subspecies contain combinations of apolipoproteins with immune regulatory functions. HDL is enriched in anti-inflammatory lipids, such as sphingosine-1-phosphate and certain saturated lysophospholipids. HDL reduces inflammation and protects against infection by modulating immune cell function, vasodilation and endothelial barrier function. HDL suppresses immune cell activation at least in part by modulating the cholesterol content in cholesterol/sphingolipid-rich membrane domains (lipid rafts), which play a critical role in the compartmentalization of signaling pathways. Acute infections, inflammation or autoimmune diseases lower HDL cholesterol levels and significantly alter HDL metabolism, composition and function. Such alterations could have a major impact on disease progression and may affect the risk for infections and cardiovascular disease. This review article aims to provide a comprehensive overview of the immune cell modulatory activities of HDL. We focus on newly discovered activities of HDL-associated apolipoproteins, enzymes, lipids, and HDL mimetic peptides.

Biologics and atherosclerotic cardiovascular risk in rheumatoid arthritis: a review of evidence and mechanistic insights

Introduction: Cardiovascular disease is a leading comorbidity in rheumatoid arthritis. Timely introduction of biologic therapies in a treat-to-target approach has optimized disease-related outcomes and attenuated accrual of comorbidities, including cardiovascular risk.Areas covered: A literature search in MEDLINE (via PubMed) was performed between January 2009 and November 2020. This manuscript explores recent developments in atherosclerotic cardiovascular risk in RA compared with non-RA individuals; it synopsizes differences in vascular function and inflammation, prevalence, burden, vulnerability, and progression of atherosclerotic plaque and their underlying cellular and molecular mechanisms. Finally, it reviews the recent literature on cardioprotective benefits of biologics and draws mechanistic links with inhibition of new plaque formation, stabilization of high-risk lesions and improvement in endothelial function, arterial stiffness, lipid metabolism, and traditional cardiac risk factors.Expert opinion: Increasing evidence points to a solid cardioprotective influence of earlier, longer, and ongoing use of biologic treatments in RA. Nevertheless, the precise mechanistic effects of plaque progression and remodeling, vascular stiffness, endothelial dysfunction, lipid metabolism, and traditional cardiac risk factors are less rigorously characterized.

TRAIL and Cardiovascular Disease-A Risk Factor or Risk Marker: A Systematic Review

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a pro-apoptotic protein showing broad biological functions. Data from animal studies indicate that TRAIL may possibly contribute to the pathophysiology of cardiomyopathy, atherosclerosis, ischemic stroke and abdominal aortic aneurysm. It has been also suggested that TRAIL might be useful in cardiovascular risk stratification. This systematic review aimed to evaluate whether TRAIL is a risk factor or risk marker in cardiovascular diseases (CVDs) focusing on major adverse cardiovascular events. Two databases (PubMed and Cochrane Library) were searched until December 2020 without a year limit in accordance to the PRISMA guidelines. A total of 63 eligible original studies were identified and included in our systematic review. Studies suggest an important role of TRAIL in disorders such as heart failure, myocardial infarction, atrial fibrillation, ischemic stroke, peripheral artery disease, and pulmonary and gestational hypertension. Most evidence associates reduced TRAIL levels and increased TRAIL-R2 concentration with all-cause mortality in patients with CVDs. It is, however, unclear whether low TRAIL levels should be considered as a risk factor rather than a risk marker of CVDs. Further studies are needed to better define the association of TRAIL with cardiovascular diseases.

Type I Interferon as cardiovascular risk factor in systemic and cutaneous lupus erythematosus: A systematic review

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) have a high burden of cardiovascular disease (CVD) of multifactorial origin. The aim of this systematic review is to analyze the role of the interferon I (IFN-I) signature and fibroblast growth factor-23 (FGF-23) in patients with SLE or cutaneous lupus erythematosus (CLE) herein.

MATERIALS AND METHODS

We conducted a systematic literature search in PubMed and Scopus using keywords for major adverse cardiovascular events (MACE) and intermediate outcomes (endothelial dysfunction, subclinical atherosclerosis, platelet activation) associated with IFN-I or FGF-23 in patients with SLE and CLE.

RESULTS

4745 citations were screened, of which 12 studies were included. IFN-I was associated with MACE in two third of the studies and the association was strongest for cardiac events. An association of IFN-I was found in all studies investigating impaired vascular function, but only in 50% (respectively 40%) of reports examining the relation of IFN-I and platelet activation (respectively subclinical atherosclerosis). Altogether the reports were of variable bias and quality due to high variability of examined IFN-I biomarkers and inconsistent results for different outcome measures. No studies investigating the cardiovascular risk of circulating IFN-I in CLE, nor FGF-23 in SLE or CLE were found.

CONCLUSION

Clinical studies measuring the association between IFN-I and direct / intermediate measures of CVD are rare and ambiguous in SLE and nonexistent in CLE, hampering a definite conclusion.

Increased apolipoprotein-B:A1 ratio predicts cardiometabolic risk in patients with juvenile onset SLE

BACKGROUND

Cardiovascular disease is a leading cause of mortality in patients with juvenile-onset systemic lupus erythematosus (JSLE). Traditional factors for cardiovascular risk (CVR) prediction are less robust in younger patients. More reliable CVR biomarkers are needed for JSLE patient stratification and to identify therapeutic approaches to reduce cardiovascular morbidity and mortality in JSLE.

METHODS

Serum metabolomic analysis (including >200 lipoprotein measures) was performed on a discovery (n=31, median age 19) and validation (n=31, median age 19) cohort of JSLE patients. Data was analysed using cluster, receiver operating characteristic analysis and logistic regression. RNA-sequencing assessed gene expression in matched patient samples.

FINDINGS

Hierarchical clustering of lipoprotein measures identified and validated two unique JSLE groups. Group-1 had an atherogenic and Group-2 had an atheroprotective lipoprotien profile. Apolipoprotein(Apo)B:ApoA1 distinguished the two groups with high specificity (96.2%) and sensitivity (96.7%). JSLE patients with high ApoB:ApoA1 ratio had increased CD8+ T-cell frequencies and a CD8+ T-cell transcriptomic profile enriched in genes associated with atherogenic processes including interferon signaling. These metabolic and immune signatures overlapped statistically significantly with lipid biomarkers associated with sub-clinical atherosclerosis in adult SLE patients and with genes overexpressed in T-cells from human atherosclerotic plaque respectively. Finally, baseline ApoB:ApoA1 ratio correlated positively with SLE disease activity index (r=0.43, p=0.0009) and negatively with Lupus Low Disease Activity State (r=-0.43, p=0.0009) over 5-year follow-up.

INTERPRETATION

Multi-omic analysis identified high ApoB:ApoA1 as a potential biomarker of increased cardiometabolic risk and worse clinical outcomes in JSLE. ApoB:ApoA1 could help identify patients that require increased disease monitoring, lipid modification or lifestyle changes.

FUNDING

Lupus UK, The Rosetrees Trust, British Heart Foundation, UCL & Birkbeck MRC Doctoral Training Programme and Versus Arthritis.

Mitochondrial DAMPs and altered mitochondrial dynamics in OxLDL burden in atherosclerosis

Atherosclerosis results in life-threatening cardiovascular pathologies, including ischemic heart disease, stroke, myocardial infarction, and peripheral arterial disease. The role of increased serum low-density lipoprotein (LDL) and resultant accumulation of oxidized-LDL (oxLDL) in atheroma formation is well established. Recent findings elucidate the significance of mitochondrial damage-associated molecular patterns (mtDAMPs) in triggering sterile inflammation in concert with oxLDL. The mtDAMPs including mitochondrial DNA (mtDNA), cytochrome C, cardiolipin, heat shock protein 60 (HSP60), mitochondrial transcription factor A (TFAM), and N-formyl peptides, are expected to possess proatherogenic roles. However, limited data are available in the literature. The mtDAMPs initiate sterile inflammation in atherosclerotic lesions via numerous signaling pathways, most of which converge to the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome. Priming the activation of the NLRP3 inflammasome, mtDAMPs promote secretion of proinflammatory cytokines, including interleukin-1β (IL-1β), implicated in atherosclerotic lesions through vascular smooth muscle and fibroblast proliferation, arterial wall thickening, and plaque formation. In this article we critically reviewed and discussed the central role of the NLRP3 inflammasome in mtDAMP-induced sterile inflammation in atherosclerosis with specific components including caspase-1, pregnane X receptor (PXR), adenosine monophosphate activated protein kinase (AMPK), protein phosphatase 2A (PP2A), thioredoxin-interacting protein (TXNIP), and downstream cytokines including IL-1β and IL-18 as potential mediators of atherosclerosis. Better understanding of the proinflammatory effects of mtDAMPs and its pathological association with oxLDL possess immense translational significance for novel therapeutic intervention.

Insulin resistance and obesity affect monocyte-derived dendritic cell phenotype and function

AIM

Cardiovascular disease (CVD) is prevalent in women after menopause, which may be associated with obesity, insulin resistance and metaflammation. Despite the recognized role of immunological mechanisms in vascular remodeling, the role of dendritic cells (DCs) is still unclear. The aim was to characterize monocyte-derived DCs (Mo-DC) in post-menopausal patients with type 2 diabetes (T2DM) and obese woman, without clinical manifestations of atherosclerosis.

METHODS

Obese post-menopausal women with or without T2DM were enrolled and were compared to age-matched healthy women. DCs obtained from patients were phenotypically and functionally characterized by flow cytometry and mixed lymphocyte reaction. MRNA integrins expression was assessed by real time RT-PCR; circulating fetuin-A and adiponectin levels were measured by ELISA.

RESULTS

Phenotypic dysregulation of Mo-DC reported was related to a defective allogenic lymphocyte stimulation and to an increased mRNA of CD11c, CD18 and DC-SIGN/CD209 which regulate their adhesion to vascular wall cells. Fetuin-A and adiponectin levels were significantly altered and negatively correlated. Hyperglycaemia significantly impaired CD14⁺ transdifferentiation into Mo-DC.

CONCLUSIONS

These data show a dysfunction of Mo-DCs obtained from precursors isolated from T2DM obese post-menopausal woman without any documented clinical CV event. Association of obesity to diabetes seems to worsen DC's phenotype and function and increase vascular inflammation.

IFN-I Mediates Dysfunction of Endothelial Progenitor Cells in Atherosclerosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease including the cardiovascular system. Atherosclerosis is the most common cardiovascular complication of SLE and a significant risk factor for morbidity and mortality. Vascular damage/protection mechanism in SLE patients is out of balance, caused by the cascade reaction among oxidative stress, proinflammatory cytokines, Neutrophil Extracellular Traps, activation of B cells and autoantibodies and abnormal T cells. As a precursor cell repairing vascular endothelium, endothelial progenitor cells (EPCs) belong to the protective mechanism and show the reduced number and impaired function in SLE. However, the pathological mechanism of EPCs dysfunction in SLE remains ill-defined. This paper reviews the latest SLE epidemiology and pathogenesis, discusses the changes in the number and function of EPCs in SLE, expounds the role of EPCs in SLE atherosclerosis, and provides new guidance and theoretical basis for exploring novel targets for SLE treatment.

Gut microbiota and atherosclerosis: role of B cell for atherosclerosis focusing on the gut-immune-B2 cell axis

Atherosclerosis is the leading cause of cardiovascular mortality and morbidity worldwide and is described as a complex disease involving several different cell types and their molecular products. Recent studies have revealed that atherosclerosis arises from a systemic inflammatory process, including the accumulation and activities of various immune cells. However, the immune system is a complicated network made up of many cell types, hundreds of bioactive cytokines, and millions of different antigens, making it challenging to readily define the associated mechanism of atherosclerosis. Nevertheless, we previously reported a potential persistent inflammatory process underlying atherosclerosis development, centered on a pathological humoral immune response between commensal microbes and activated subpopulations of substantial B cells in the vicinity of the arterial adventitia. Accumulating evidence has indicated the importance of gut microbiota in atherosclerosis development. Commensal microbiota are considered important regulators of immunity and metabolism and also to be possible antigenic sources for atherosclerosis development. However, the interplay between gut microbiota and metabolism with regard to the modulation of atherosclerosis-associated immune responses remains poorly understood. Here, we review the mechanisms by which the gut microbiota may influence atherogenesis, with particular focus on humoral immunity and B cells, especially the gut-immune-B2 cell axis.

Graphical abstract

Dendritic Cells and T Cells, Partners in Atherogenesis and the Translating Road Ahead

Atherosclerosis is a chronic process associated with arterial inflammation, the accumulation of lipids, plaque formation in vessel walls, and thrombosis with late mortal complications such as myocardial infarction and ischemic stroke. Immune and inflammatory responses have significant effects on every phase of atherosclerosis. Increasing evidence has shown that both innate and adaptive “arms” of the immune system play important roles in regulating the progression of atherosclerosis. Accumulating evidence suggests that a unique type of innate immune cell, termed dendritic cells (DCs), play an important role as central instigators, whereas adaptive immune cells, called T lymphocytes, are crucial as active executors of the DC immunity in atherogenesis. These two important immune cell types work in pairs to establish pro-atherogenic or atheroprotective immune responses in vascular tissues. Therefore, understanding the role of DCs and T cells in atherosclerosis is extremely important. Here, in this review, we will present a complete overview, based on existing knowledge of these two cell types in the atherosclerotic microenvironment, and discuss some of the novel means of targeting DCs and T cells as therapeutic tactics for the treatment of atherosclerosis.

Emerging roles of Toll-like receptor 9 in cardiometabolic disorders

Growing evidence suggests that damage-associated molecule patterns (DAMPs) and their receptors, pattern recognition receptors (PRRs), are associated with the progression of cardiometabolic disorders, including obesity-related insulin resistance and atherosclerosis. Cardiometabolic disorders share sterile chronic inflammation as a major cause; however, the exact mechanisms are still obscure. Toll-like receptor 9 (TLR9), one of the nucleic acid-sensing TLRs, recognizes DNA fragments derived from pathogens and contributes to self-defense by activation of the innate immune system. In addition, previous studies demonstrated that TLR9 recognizes DNA fragments released from host cells, accelerating sterile inflammation, which is associated with inflammatory diseases such as autoimmune diseases. In obese adipose tissue and atherosclerotic vascular tissue, various stresses release DNA fragments and/or nuclear proteins as DAMPs from degenerated adipocytes and vascular cells. Recent studies indicated that the activation of TLR9 in immune cells including macrophages and dendritic cells by recognition of these DAMPs promotes inflammation in these tissues, which causes cardiometabolic disorders. This review discusses recent advances in understanding the role of sterile inflammation associated with TLR9 and its endogenous ligands in cardiometabolic disorders. New insights into innate immunity may provide better understanding of cardiometabolic disorders and new therapeutic options for these major health threats in recent decades.

Type-I interferons in atherosclerosis

Chen et al. review the effects of type-I IFNs and the potential of anti–type-I IFN therapies in atherosclerosis.

The contribution of dyslipidemia and inflammation in atherosclerosis is well established. Along with effective lipid-lowering treatments, the recent success of clinical trials with anti-inflammatory therapies and the accelerated atherosclerosis in many autoimmune diseases suggest that targeting inflammation may open new avenues for the prevention and the treatment for cardiovascular diseases (CVDs). In the past decades, studies have widened the role of type-I interferons (IFNs) in disease, from antivirus defense to autoimmune responses and immuno-metabolic syndromes. While elevated type-I IFN level in serum is associated with CVD incidence in patients with interferonopathies, experimental data have attested that type-I IFNs affect plaque-residing macrophages, potentiate foam cell and extracellular trap formation, induce endothelial dysfunction, alter the phenotypes of dendritic cells and T and B lymphocytes, and lead to exacerbated atherosclerosis outcomes. In this review, we discuss the production and the effects of type-I IFNs in different atherosclerosis-associated cell types from molecular biology studies, animal models, and clinical observations, and the potential of new therapies against type-I IFN signaling for atherosclerosis.

T cell subsets and functions in atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the arterial wall and the primary underlying cause of cardiovascular disease. Data from in vivo imaging, cell-lineage tracing and knockout studies in mice, as well as clinical interventional studies and advanced mRNA sequencing techniques, have drawn attention to the role of T cells as critical drivers and modifiers of the pathogenesis of atherosclerosis. CD4+ T cells are commonly found in atherosclerotic plaques. A large body of evidence indicates that T helper 1 (TH1) cells have pro-atherogenic roles and regulatory T (Treg) cells have anti-atherogenic roles. However, Treg cells can become pro-atherogenic. The roles in atherosclerosis of other TH cell subsets such as TH2, TH9, TH17, TH22, follicular helper T cells and CD28null T cells, as well as other T cell subsets including CD8+ T cells and γδ T cells, are less well understood. Moreover, some T cells seem to have both pro-atherogenic and anti-atherogenic functions. In this Review, we summarize the knowledge on T cell subsets, their functions in atherosclerosis and the process of T cell homing to atherosclerotic plaques. Much of our understanding of the roles of T cells in atherosclerosis is based on findings from experimental models. Translating these findings into human disease is challenging but much needed. T cells and their specific cytokines are attractive targets for developing new preventive and therapeutic approaches including potential T cell-related therapies for atherosclerosis.

Innate Immune Receptors, Key Actors in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death in the industrialized world. Most CVDs are associated with increased inflammation that arises mainly from innate immune system activation related to cardiac damage. Sustained activation of the innate immune system frequently results in maladaptive inflammatory responses that promote cardiovascular dysfunction and remodeling. Much research has focused on determining whether some mediators of the innate immune system are potential targets for CVD therapy. The innate immune system has specific receptors-termed pattern recognition receptors (PRRs)-that not only recognize pathogen-associated molecular patterns, but also sense danger-associated molecular signals. Activation of PRRs triggers the inflammatory response in different physiological systems, including the cardiovascular system. The classic PRRs, toll-like receptors (TLRs), and the more recently discovered nucleotide-binding oligomerization domain-like receptors (NLRs), have been recently proposed as key partners in the progression of several CVDs (e.g., atherosclerosis and heart failure). The present review discusses the key findings related to the involvement of TLRs and NLRs in the progression of several vascular and cardiac diseases, with a focus on whether some NLR subtypes (nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain-containing receptor 3 and nucleotide-binding oligomerization domain-containing protein 1) can be candidates for the development of new therapeutic strategies for several CVDs.

Dare to Compare. Development of Atherosclerotic Lesions in Human, Mouse, and Zebrafish

Cardiovascular diseases, such as atherosclerosis, are the leading cause of death worldwide. Although mice are currently the most commonly used model for atherosclerosis, zebrafish are emerging as an alternative, especially for inflammatory and lipid metabolism studies. Here, we review the history of in vivo atherosclerosis models and highlight the potential for future studies on inflammatory responses in lipid deposits in zebrafish, based on known immune reactions in humans and mice, in anticipation of new zebrafish models with more advanced atherosclerotic plaques.

The Role of Toll-like Receptors in Atherothrombotic Cardiovascular Disease

Toll-like receptors (TLRs) are dominant components of the innate immune system. Activated by both pathogen-associated molecular patterns and damage-associated molecular patterns, TLRs underpin the pathology of numerous inflammation related diseases that include not only immune diseases, but also cardiovascular disease (CVD), diabetes, obesity, and cancers. Growing evidence has demonstrated that TLRs are involved in multiple cardiovascular pathophysiologies, such as atherosclerosis and hypertension. Specifically, a trial called the Canakinumab Anti-inflammatory Thrombosis Outcomes Study showed the use of an antibody that neutralizes interleukin-1β, reduces the recurrence of cardiovascular events, demonstrating inflammation as a therapeutic target and also the research value of targeting the TLR system in CVD. In this review, we provide an update of the interplay between TLR signaling, inflammatory mediators, and atherothrombosis, with an aim to identify new therapeutic targets for atherothrombotic CVD.

Toll-like Receptors as a Potential Drug Target for Diabetes Mellitus and Diabetes-associated Complications

Diabetes mellitus (DM) is a chronic endocrine disease distinguished by hyperglycemia due to disturbance in carbohydrate or lipid metabolism or insulin function. To date, diabetes, and its complications, is established as a global cause of morbidity and mortality. The intended aim during the management of diabetes is to maintain blood glucose close to normal because the majority of patients have poor control of their elevated blood glucose and are highly prone to severe macrovascular and microvascular complications. To decrease the burden of the disease and its complications, scientists from various disciplines are working intensively to identify novel and promising drug targets for diabetes and its complications. Increased and ongoing investigations on mechanisms relating to diabetes and associated complications could potentially consider inflammatory cascades as a promising component of the strategy in the prevention and control of diabetes and its complications. The potential of targeting mediators of inflammation like toll-like receptors (TLRs) are part of current investigation by the scientific community. Hence, the aim of the present review is to discuss the role of TLRs as a potential drug target for diabetes and diabetes associated complications.

Development of an effective liposomal cholesterol ester transfer protein (CETP) vaccine for protecting against atherosclerosis in rabbit model

Clinical trials of cholesterol ester transfer protein (CETP) peptide vaccine were stopped after disappointing results in humans due to the inadequacy of adjuvant aluminum hydroxide in stimulating the immune response against the self-antigen of CETP. To increase the efficacy of the CETP vaccine, we developed a novel liposomal form of tetanus toxoid-CETP (TT-CETP) peptide (Lip CETP) with well-characterized properties and high encapsulation efficiency. The vaccine efficacy against atherosclerosis was evaluated in rabbits challenged with a high cholesterol diet. Rabbits were immunized with Lip-CETP or liposome containing CETP with CpG ODN (Lip CETP/CpG). Control groups received empty liposomes or buffer. Anti-TT-CETP specific antibodies in serum were determined and gene expression of cytokine IFN-γ and IL-4 were measured in blood peripheral mononuclear cells. Therapeutic response was evaluated by titration of plasma lipoproteins during the study and pathologic analysis of aorta atherosclerotic lesions at the end. Lip-CETP/CpG elicited strong anti-TT-CETP antibodies and a higher IFN-γ level than the buffer. IL-4 was lower than the buffer in all vaccinated groups. Plasma lipoproteins showed no significant difference in the studied groups. Atherosclerosis thickness grade of the aorta was lower than the buffer group (p < 0.001) in rabbits vaccinated with Lip-CETP but not with Lip-CETP/CpG. In conclusion, Lip-CETP showed a strong atheroprotective effect.

Immune cells in carotid artery plaques: what can we learn from endarterectomy specimens?

INTRODUCTION

Endarterectomy specimens represent a unique opportunity to study atherosclerosis. This review aims to summarize the recent knowledge of atherogenesis from studies characterizing a cellular composition of carotid endarterectomy specimens.

EVIDENCE ACQUISITION

A non-systematic literature review was carried out to summarize recent knowledge regarding ex vivo analysis of carotid artery plaque composition. Upon evaluation of their relevance, and elaborate forward and backward search, 95 articles were included in the review.

EVIDENCE SYNTHESIS

Despite the significant advancement of in vivo imaging techniques, the stroke prediction based on carotid artery plaque morphology is not reliable. Besides analyses of plaque morphology, present studies focus on precise characterization of the different immune cell types and elucidation of their role in plaque development. Plaque content analyses revealed the presence of various immune cells in carotid artery plaques. Presence of different immune cells subpopulations can be connected to some undesirable changes in plaque stability.

CONCLUSIONS

Since the destabilization of the atherosclerotic plaque is a multifactorial process, a combination of various methods should be used to characterize the unstable plaques more accurately. In this context, studies characterizing plaque content from a cellular point of view could elucidate some processes underlying the plaque progression. Together with morphological evaluation, these analyses could enable more precise assessment of plaque stability.

Increased risk of coronary heart disease among patients with idiopathic inflammatory myositis: a nationwide population study in Taiwan

OBJECTIVE

To evaluate the risk of incident coronary heart disease (CHD) among patients with DM and PM in a general population context.

METHODS

We conducted a retrospective cohort study using the Taiwan National Health Insurance Research Database containing records covering the years from 2000 to 2010. DM and PM were confined for the purposes of this study to those aged ⩾18 years who were eligible for the Taiwan catastrophic illness certificate. The diagnoses, CHD outcomes and cardiovascular risk factors were identified from electronic claims data. We conducted two cohort analyses: CHD and DM, and CHD and PM, excluding for each analysis individuals with CHD already identified at baseline. Data for the comparison group was obtained from the Longitudinal Health Insurance database, comprising 1 million persons randomly sampled from the total beneficiaries during 2000. We estimated hazard ratios comparing myositis with comparison cohorts, adjusting for potential cardiovascular risk factors.

RESULTS

A total of 1145 patients with idiopathic myositis were identified, along with 732 723 control patients aged ⩾18 years. The incidence rates of CHD were 15.1 in DM and 30.1 in PM per 1000 person-years, vs 8.4 and 10.5 per 1000 person-years in the comparison cohort. The adjusted hazard ratios for CHD in patients with idiopathic myositis were 2.21 (95% CI 1.64, 2.99) for DM and 3.73 (95% CI 2.83, 4.90) for PM.

CONCLUSION

Results of this general population-based cohort study suggest that DM and PM are associated with an increased risk of CHD.

Immune-Inflammatory Responses in Atherosclerosis: The Role of Myeloid Cells

Inflammation plays a key role in the initiation and progression of atherosclerosis and can be caused by multiple agents, including increased concentration of circulating low-density lipoprotein (LDL) cholesterol. Areas of the arterial wall affected by atherosclerosis are enriched with lymphocytes and dendritic cells (DCs). Atherosclerotic plaques contain a variety of proinflammatory immune cells, such as macrophages, DCs, T cells, natural killer cells, neutrophils and others. Intracellular lipid accumulation in atherosclerotic plaque leads to formation of so-called foam cells, the cytoplasm of which is filled with lipid droplets. According to current understanding, these cells can also derive from the immune cells that engulf lipids by means of phagocytosis. Macrophages play a crucial role in the initial stages of atherogenesis by engulfing oxidized LDL (oxLDL) in the intima that leads to their transformation to foam cells. Dying macrophages inside the plaque form a necrotic core that further aggravates the lesion. Proinflammatory DCs prime differentiation of naïve T cells to proinflammatory Th1 and Th17 subsets. In this review, we discuss the roles of cell types of myeloid origin in atherosclerosis-associated inflammation.

Chlamydia and Lipids Engage a Common Signaling Pathway That Promotes Atherogenesis

BACKGROUND

Recent studies indicate that Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) signaling promote the development of high fat diet-induced atherosclerosis in hypercholesterolemic mice.

OBJECTIVES

The authors investigated the role of TLR4/MyD88 signaling in hematopoietic and stromal cells in the development and infection-mediated acceleration of atherosclerosis.

METHODS

The authors generated bone marrow chimeras between wild-type and Tlr4^-/- mice, as well as wild-type and Myd88^-/- mice. All mice were on the Apoe^-/- background and fed high fat diet. The authors infected the chimeric mice with C. pneumoniae (CP) and fed them high fat diet.

RESULTS

Aortic sinus plaques and lipid content were significantly reduced in Apoe^-/- mice that received Tlr4^-/-or Myd88^-/- bone marrow compared with control animals despite similar cholesterol levels. Similarly, Tlr4 or Myd88 deficiency in stromal cells also led to a reduction in the lesion area and lipid in aortic sinus plaques. MyD88 expression only in CD11c+ dendritic cells (myeloid cells) in cells was sufficient in otherwise MyD88-deficient mice to induce CP infection-mediated acceleration of atherosclerosis, underlining the key role of MyD88 in CD11c+ dendritic cells (myeloid cells). Whereas CP infection markedly accelerated atherosclerosis in TLR4- or MyD88-positive chimeras, CP infection had a minimal effect on atherosclerosis in TLR4- or MyD88-deficient mice (either in the hematopoietic or stromal cell compartments).

CONCLUSIONS

The authors show that both CP infection and metabolic stress associated with dyslipidemia use the same innate immune response pathway, utilizing TLR4/MyD88 signaling, with similar relative contributions in bone marrow-derived hematopoietic cells and in stromal cells. Further studies are required to understand this intricate and complex cross talk among innate and adaptive immune systems in various conditions to more effectively design dendritic cell-mediated atheroprotective vaccines and other therapeutic strategies.

The P-selectin and PSGL-1 axis accelerates atherosclerosis via activation of dendritic cells by the TLR4 signaling pathway. Cell Death Dis. 2019;10:507. [PMID: 31263109 PMCID: PMC6602970 DOI: 10.1038/s41419-019-1736-5]

P-selectin and dendritic cells (DCs) are associated with atherosclerosis. However, their interactions in this setting are undefined. Herein, we investigated the role of P-selectin and its receptor P-selectin glycoprotein ligand (PSGL)-1 on atherosclerosis via activation of DCs. In the current study, a total of 34 patients with ST elevation myocardial infarction (STEMI) and 34 healthy control subjects were enrolled. Serum concentration of P-selectin was higher and the myeloid DC/plasmacytoid DC (mDC/pDC) ratio was lower in STEMI patients than in normal individuals. Interestingly, in STEMI patients, P-selectin was decreased and the mDC/pDC ratio was increased at 5–7 days after successful percutaneous coronary intervention, as compared with values on admission. Serum P-selectin was inversely correlated with the mDC/pDC ratio. Moreover, ApoE^−/−P^−/− and ApoE^−/−PSGL-1^−/− mice developed small atherosclerotic plaques after feeding of a western diet for 12 weeks and DC infiltration was significantly reduced. P-selectin stimulation markedly induced phenotypic maturation, enhanced secretion of inflammatory cytokines, communication with T cells, and the adhesion and migration of DCs. In vivo, DC maturation was significantly attenuated in P-selectin and PSGL1 knockout mice under hypercholesterolemic and inflammatory conditions. These effects were associated with the activation of myeloid differentiation primary response 88 (MYD88)-dependent and MyD88-independent Toll-like receptor 4 (TLR4) signaling pathways. Taken together, binding of P-selectin to PSGL-1 on DCs contributes to atherosclerosis progression via DC activation via the TLR4 signaling pathway.

[Unusual cause of acute coronary syndrome: Horton's disease]

The pathophysiology of acute coronary syndromes is in most cases due to the erosion or rupture of a plaque with consequent thrombotic obstruction of coronary artery. In a few cases, the mechanism is different, this not modifying the initial management but imposing special techniques for diagnosis and therapeutic management. We report a clinical case of a patient supported for an acute coronary syndrome, in a context of impaired general condition and biological inflammatory syndrome revealing a Horton's disease.