Genetic susceptibility to atherosclerosis

Identification of novel genes associated with atherosclerosis in Bama miniature pig

BACKGROUND

Atherosclerosis is a chronic cardiovascular disease of great concern. However, it is difficult to establish a direct connection between conventional small animal models and clinical practice. The pig's genome, physiology, and anatomy reflect human biology better than other laboratory animals, which is crucial for studying the pathogenesis of atherosclerosis.

METHODS

We used whole-genome sequencing data from nine Bama minipigs to perform a genome-wide linkage analysis, and further used bioinformatic tools to filter and identify underlying candidate genes. Candidate gene function prediction was performed using the online prediction tool STRING 12.0. Immunohistochemistry and immunofluorescence were used to detect the expression of proteins encoded by candidate genes.

RESULTS

We mapped differential single nucleotide polymorphisms (SNPs) to genes and obtained a total of 102 differential genes, then we used GO and KEGG pathway enrichment analysis to identify four candidate genes, including SLA-1, SLA-2, SLA-3, and TAP2. nsSNPs cause changes in the primary and tertiary structures of SLA-I and TAP2 proteins, the primary structures of these two proteins have undergone amino acid changes, and the tertiary structures also show slight changes. In addition, immunohistochemistry and immunofluorescence results showed that the expression changes of TAP2 protein in coronary arteries showed a trend of increasing from the middle layer to the inner layer.

CONCLUSIONS

We have identified SLA-I and TAP2 as potential susceptibility genes of atherosclerosis, highlighting the importance of antigen processing and immune response in atherogenesis.

Association of LDLR, TP53 and MMP9 Gene Polymorphisms With Atherosclerosis in a Malaysian Study Population

Preliminary research has shown that low density lipoprotein receptor (LDLR), tumor protein (TP53) and matrix metalloproteinase 9 (MMP9) genes expression levels were significantly increased in atherosclerosis coronary artery tissue (ACAT) compared to non-atherosclerotic coronary artery tissue (NCAT) samples. Thus, further investigation was carried out to study the association of LDLR, TP53 and MMP9 gene polymorphisms and the risk of developing atherosclerosis (ATH) in a Malaysian population. Single nucleotide polymorphisms of C88S, TP53 codon 72 and MMP9C>T were analyzed in 76 ACAT samples and 149 NCAT samples, representing cases and controls, respectively. In results, heterozygous CT genotype of MMP9C>T polymorphism was significantly higher in ACAT compared to NCAT samples (57.9% vs 27.5%, χ² = 19.758, df= 1, P < 0.05). The CT genotype was found to be significantly associated with the risk of developing ATH (OR = 3.622, 95% CI = 2.028-6.470). However, the distribution of the CT genotype in a healthy Malaysian study population was incomparable regardless of gender and ethnicity. The DNA sequencing results validated the C88S, TP53 codon 72, and MMP9C>T polymorphisms. In conclusion, the CT genotype of the MMP9-1562C>T polymorphism was found to have a strong association with the risk of developing ATH.

Proprotein convertase subtilisin/kexin type 9 genetic screening using the vervet (Chlorocebus aethiops) model

BACKGROUND

The proprotein convertase subtilisin/kexin type 9 (PCSK9) gene has come to prominence due to its reported function in the clearance of low-density lipoprotein cholesterol. The vervet monkey (Chlorocebus aethiops) was utilized to study the genetics of PCSK9 gene.

METHOD

Sixteen vervet monkeys were selected to screen for possible PCSK9 polymorphisms and to determine gene expression.

RESULTS

Four PCSK9 sequence variants (T112T, R148S, H177N and G635G) were identified and three of these variants (H177N, R148S, and G635G) were categorized as loss of function mutations. A decline in gene expression levels was also observed in animals harboring these three variants. Although the selected variants might have affected the level of gene expression in the selected animals, individual variation was also noticed in some of these individuals with the G635G variant.

CONCLUSION

Based on the findings obtained from this study, it is suggestive that the activity of PCSK9 was hindered.

Genetic Risk Factors of Intracranial Atherosclerosis

PURPOSE OF REVIEW

Intracranial atherosclerosis (ICAS) is the most common cause of stroke throughout the world. It also increases the risk of recurrent stroke and dementia. As a complex and multifactorial disease, ICAS is influenced by multiple genetic, biological, and environmental factors. This review summarizes the candidate gene and genome-wide studies aimed at discovering genetic risk factors of ICAS.

RECENT FINDINGS

Numerous studies have focused on the association between single-nucleotide polymorphisms (SNPs) of atherosclerosis-related genes and the risk of ICAS. Variants in adiponectin Q (ADIPOQ), ring finger protein 213 (RNF213), apolipoprotein E (APOE), phosphodiesterase 4D (PDE4D), methylenetetrahydrofolate reductase (MTHFR), lipoprotein lipase (LPL), α-adducin (ADD1) genes, angiotensin-converting enzyme (ACE), and other genes related to renin-angiotensin-aldosterone system have been associated with ICAS. We review the available evidences on the candidate genes and SNPs associated with genetic susceptibility to ICAS, and point out future developments of this field. Genetic discoveries could have clinical implications for intracranial atherosclerotic disease.

The Long Non-Coding RNA Landscape of Atherosclerotic Plaques

Currently, cardiovascular diseases continue to be the leading cause of death worldwide; therefore, atherosclerosis remains one of the most crucial public health problems. This chronic and complex disease is considered to be a result of aberrant lipid homeostasis and inflammation of the inner wall of arteries that leads to plaque development. In recent years, a specific class of non-coding RNAs that are characterised by transcript lengths longer than 200 nucleotides, called long non-coding RNAs (lncRNAs), has emerged. Moreover, a growing body of evidence indicates that deregulation of lncRNA expression may contribute to the development of many diseases. Despite continuous efforts in deciphering the molecular basis of atherosclerotic plaque (AP) formation, many aspects of this process remain elusive. Therefore, continuing efforts in this area should remain the highest priority in the coming years. Establishment of a standardised experimental pipeline and validation of lncRNAs as possible relevant biomarkers for cardiovascular disease would enable the translation of gathered findings into clinical practice.

Conceptualization of Heterogeneity of Chronic Diseases and Atherosclerosis as a Pathway to Precision Medicine: Endophenotype, Endotype, and Residual Cardiovascular Risk

The article discusses modern approaches to the conceptualization of pathogenetic heterogeneity in various branches of medical science. The concepts of endophenotype, endotype, and residual cardiovascular risk and the scope of their application in internal medicine and cardiology are considered. Based on the latest results of studies of the genetic architecture of atherosclerosis, five endotypes of atherosclerosis have been proposed. Each of the presented endotypes represents one or another pathophysiological mechanism of atherogenesis, having an established genetic substrate, a characteristic panel of biomarkers, and a number of clinical features. Clinical implications and perspectives for the study of endotypes of atherosclerosis are briefly reviewed.

Functional lncRNA-miRNA-mRNA networks in rabbit carotid atherosclerosis

Atherosclerosis is one of the most common clinical cardiovascular disorders. Accumulating evidence indicates that lncRNAs exert critical functions in atherosclerosis; however, their functional roles and regulatory mechanisms remain unclear. In this study, we induced atherosclerotic plaques in three rabbit carotid arteries through an atherogenic diet and balloon injury; three age-matched rabbits were fed normal chow and served as controls. We thoroughly investigated the RNA (mRNA, lncRNA and miRNA) expression profiles in atherosclerotic rabbit carotid models with deep RNA sequencing. We identified several significantly differentially expressed RNAs. The corresponding lncRNA-miRNA-mRNA network was constructed, and the significantly dysregulated network was selected. Furthermore, Gene Ontology and  Kyoto Encyclopedia of Genes and Genomes analyses indicated that the mRNAs in the network were involved in leukocyte activation, cell proliferation, cell adhesion molecules and cytokine-cytokine receptor interaction. After rigorous screening, we obtained a differentially expressed lncRNA-miRNA-mRNA interaction network associated with atherosclerosis. In the network, XLOC_054118 and XLOC_030217 upregulate the CHI3L1, SOAT, CTSB and CAPG genes by competitively binding to the miRNA ocu-miR-96-5p. XLOC_062719 and XLOC_063297 upregulate CTSS, CTSB and EDNRA genes by competitively binding to the miRNA ocu-miR-185-5p.

Developing Novel Therapeutic Strategies Against Ring Finger Protein 213 Vasculopathy: Is It an Achievable Goal?

See Article Choi et al.

KRIT1 Deficiency Promotes Aortic Endothelial Dysfunction

Loss-of-function mutations of the gene encoding Krev interaction trapped protein 1 (KRIT1) are associated with the pathogenesis of Cerebral Cavernous Malformation (CCM), a major cerebrovascular disease characterized by abnormally enlarged and leaky capillaries and affecting 0.5% of the human population. However, growing evidence demonstrates that KRIT1 is implicated in the modulation of major redox-sensitive signaling pathways and mechanisms involved in adaptive responses to oxidative stress and inflammation, suggesting that its loss-of-function mutations may have pathological effects not limited to CCM disease. The aim of this study was to address whether KRIT1 loss-of-function predisposes to the development of pathological conditions associated with enhanced endothelial cell susceptibility to oxidative stress and inflammation, such as arterial endothelial dysfunction (ED) and atherosclerosis. Silencing of KRIT1 in human aortic endothelial cells (HAECs), coronary artery endothelial cells (HCAECs), and umbilical vein endothelial cells (HUVECs) resulted in increased expression of endothelial proinflammatory adhesion molecules vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) and in enhanced susceptibility to tumor necrosis factor alpha (TNF-α)-induced apoptosis. These effects were associated with a downregulation of Notch1 activation that could be rescued by antioxidant treatment, suggesting that they are consequent to altered intracellular redox homeostasis induced by KRIT1 loss-of-function. Furthermore, analysis of the aorta of heterozygous KRIT1^+/- mice fed a high-fructose diet to induce systemic oxidative stress and inflammation demonstrated a 1.6-fold increased expression of VCAM-1 and an approximately 2-fold enhanced fat accumulation (7.5% vs 3.6%) in atherosclerosis-prone regions, including the aortic arch and aortic root, as compared to corresponding wild-type littermates. In conclusion, we found that KRIT1 deficiency promotes ED, suggesting that, besides CCM, KRIT1 may be implicated in genetic susceptibility to the development of atherosclerotic lesions.

Cross-talk between renal lithogenesis and atherosclerosis: an unveiled link between kidney stone formation and cardiovascular diseases

The prevalence of kidney stones and cardiovascular diseases (CVDs) are increasing throughout the world. Both diseases are chronic and characterized by accumulation of oxidized proteins and lipids in the renal tissue and arterial wall, respectively. Emerging studies have revealed a positive association between nephrolithiasis and CVDs. Based on preclinical and clinical evidences, this review discusses: (i) stone forming risk factors, crystal nucleation, aggregation, injury-induced crystal retention, and stone formation, (ii) CVD risk factors such as dyslipidemia, perturbation of gut microbiome, obesity, free radical-induced lipoprotein oxidation, and retention in the arterial wall, subsequent foam cell formation, and atherosclerosis, (iii) mechanism by which stone forming risk factors such as oxalate, calcium, uric acid, and infection contribute toward CVDs, and (iv) how CVD risk factors, such as cholesterol, phospholipids, and uric acid, contribute to kidney stone formation are described.

The Therapeutic Potential of Anti-Inflammatory Exerkines in the Treatment of Atherosclerosis

Although many cardiovascular (CVD) medications, such as antithrombotics, statins, and antihypertensives, have been identified to treat atherosclerosis, at most, many of these therapeutic agents only delay its progression. A growing body of evidence suggests physical exercise could be implemented as a non-pharmacologic treatment due to its pro-metabolic, multisystemic, and anti-inflammatory benefits. Specifically, it has been discovered that certain anti-inflammatory peptides, metabolites, and RNA species (collectively termed “exerkines”) are released in response to exercise that could facilitate these benefits and could serve as potential therapeutic targets for atherosclerosis. However, much of the relationship between exercise and these exerkines remains unanswered, and there are several challenges in the discovery and validation of these exerkines. This review primarily highlights major anti-inflammatory exerkines that could serve as potential therapeutic targets for atherosclerosis. To provide some context and comparison for the therapeutic potential of exerkines, the anti-inflammatory, multisystemic benefits of exercise, the basic mechanisms of atherosclerosis, and the limited efficacies of current anti-inflammatory therapeutics for atherosclerosis are briefly summarized. Finally, key challenges and future directions for exploiting these exerkines in the treatment of atherosclerosis are discussed.

Association of Cholesteryl Ester Transfer Protein (CETP) Gene -629C/A Polymorphism with Angiographically Proven Atherosclerosis

Association of cholesteryl ester transfer protein (CETP) Gene -629C/A Polymorphism with angiographically proven atherosclerosis CETP gene has been linked to CAD risk via its role in HDL and LDL metabolism. There is no agreement of whether CETP is atherogenic or not. Furthermore, various genotypes of CETP gene have been associated with CETP levels and thus with atherosclerosis risk. Our aim was to study the association of CETP -629C/A gene polymorphism with CETP and HDL levels and their association if any with atherosclerosis. Study population consisted of angiographically documented 50 cases with coronary artery atherosclerosis and 50 controls negative for atherosclerosis of coronary artery. Serum lipid profile was measured on SYNCHRON CX-9 using standard kits. Serum CETP levels were measured by ELISA method. CETP -629C/A gene polymorphism was studied using PCR-RFLP method. There was no significant difference in lipid profile of the two groups. However, serum CETP level was significantly higher (46.44 ± 21.75 ng/ml) in cases than controls (37.10 ± 21.92 ng/ml) with p value =0.035. The frequency of -629A allele was higher (0.85) in cases than that of controls (0.81). Homozygosity of A allele was more in subjects with atherosclerosis of coronary artery. We conclude that CETP is atherogenic and could be used as atherogenic risk predictor in angiographically proven atherosclerosis. Also A allele of -629C/A polymorphism is more prevalent in cases; indicating its effect on expression of CETP gene.

Association of Serum hs-CRP Levels With the Presence of Obesity, Diabetes Mellitus, and Other Cardiovascular Risk Factors

BACKGROUND

Diabetes mellitus remains one of the major health problems of the 21st century and is associated with comorbidities including obesity and metabolic abnormalities. The study was conducted to evaluate serum high-sensitivity C-reactive protein (hs-CRP) levels, as a marker of inflammation, in a large sample of Iranian population without a history of cardiovascular or inflammatory disease and cancer, and to relate this to fasting blood glucose (FBG) and the presence of diabetes mellitus.

METHODS

The study consisted of 7,762 subjects divided into four groups-nonobese/nondiabetic, obese/nondiabetic, nonobese/diabetic and obese/diabetic-based on the BMI classification and their FBG. Anthropometric characteristics were measured and blood was collected for the evaluation of fasted lipid profile, FBG and serum hs-CRP levels.

RESULTS

Several clinical and biochemical characteristics were significantly different among the four groups: FBG, P < 0.001; total cholesterol (TC), P < 0.001; and triglyceride (TG), P < 0.001. The subjects with a serum hs-CRP >3 mg/dl had higher TC (P < 0.001), low-density lipoprotein cholesterol (LDL-C, P < 0.001), TG (P < 0.001), fat percentage (P < 0.001), and systolic and diastolic blood pressure (P < 0.001) compared with subjects with a serum hs-CRP <3 mg/dl. Multivariate analysis showed FBG, LDL-C, and waist circumference (WC) associated with increased serum hs-CRP levels (P < 0.001).

CONCLUSIONS

FBG, LDL-C, WC and gender are independently associated with serum hs-CRP concentrations.

Metabolic Diseases Downregulate the Majority of Histone Modification Enzymes, Making a Few Upregulated Enzymes Novel Therapeutic Targets--"Sand Out and Gold Stays"

To determine whether the expression of histone modification enzymes is regulated in physiological and pathological conditions, we took an experimental database mining approach pioneered in our labs to determine a panoramic expression profile of 164 enzymes in 19 human and 17 murine tissues. We have made the following significant findings: (1) Histone enzymes are differentially expressed in cardiovascular, immune, and other tissues; (2) our new pyramid model showed that heart and T cells are among a few tissues in which histone acetylation/deacetylation, and histone methylation/demethylation are in the highest varieties; and (3) histone enzymes are more downregulated than upregulated in metabolic diseases and regulatory T cell (Treg) polarization/ differentiation, but not in tumors. These results have demonstrated a new working model of "Sand out and Gold stays," where more downregulation than upregulation of histone enzymes in metabolic diseases makes a few upregulated enzymes the potential novel therapeutic targets in metabolic diseases and Treg activity.

MIF and CXCL12 in Cardiovascular Diseases: Functional Differences and Similarities

Coronary artery disease (CAD) as part of the cardiovascular diseases is a pathology caused by atherosclerosis, a chronic inflammatory disease of the vessel wall characterized by a massive invasion of lipids and inflammatory cells into the inner vessel layer (intima) leading to the formation of atherosclerotic lesions; their constant growth may cause complications such as flow-limiting stenosis and plaque rupture, the latter triggering vessel occlusion through thrombus formation. Pathophysiology of CAD is complex and over the last years many players have entered the picture. One of the latter being chemokines (small 8-12 kDa cytokines) and their receptors, known to orchestrate cell chemotaxis and arrest. Here, we will focus on the chemokine CXCL12, also known as stromal cell-derived factor 1 (SDF-1) and the chemokine-like function chemokine, macrophage migration-inhibitory factor (MIF). Both are ubiquitously expressed and highly conserved proteins and play an important role in cell homeostasis, recruitment, and arrest through binding to their corresponding chemokine receptors CXCR4 (CXCL12 and MIF), ACKR3 (CXCL12), and CXCR2 (MIF). In addition, MIF also binds to the receptor CD44 and the co-receptor CD74. CXCL12 has mostly been studied for its crucial role in the homing of (hematopoietic) progenitor cells in the bone marrow and their mobilization into the periphery. In contrast to CXCL12, MIF is secreted in response to diverse inflammatory stimuli, and has been associated with a clear pro-inflammatory and pro-atherogenic role in multiple studies of patients and animal models. Ongoing research on CXCL12 points at a protective function of this chemokine in atherosclerotic lesion development. This review will focus on the role of CXCL12 and MIF and their differences and similarities in CAD of high risk patients.

Impact of viral and bacterial infections in coronary artery disease patients

Atherosclerosis is becoming an alarming disease for the existence of healthy human beings in the 21^st century. There are a growing number of agents, either modernized life style generated, competitive work culture related or infection with some bacterial or viral agents, documented every year. These infectious agents do not have proper diagnostics or detection availability in many poor and developing countries. Hence, as active medical researchers, we summarize some aspects of infectious agents and their related mechanisms in this review which may be beneficial for new beginners in this field and update awareness in the field of cardiovascular biology.

IRS1, TCF7L2, ADRB1, PPARG, and HHEX polymorphisms associated with atherogenic risk in Mexican population

Objective. We aimed to explore the association between polymorphisms of IRS1 (rs1801278), TCF7L2 (rs7903146 and rs12255372), ADRB1 (rs1801253), PPARG (rs1801282), and HHEX (rs5015480) genes with atherogenic risk (AI = Total cholesterol/HDL) in MetS, T2D, and healthy populations from the Mexican Social Security Institute. Methodology and Results. Four hundred thirty-five MetS, 517 T2D, and 547 healthy individuals were selected. The association between the SNPs and the atherogenic index was evaluated by multiple linear regression and multinomial logistic regression models. The ADRB1 gene showed a statistically significant association with high-risk atherogenic index, OR = 2.94 (IC 95% 1.64-5.24; P < 0.0001) for the Arg/Gly variant, under the dominant model an OR = 2.96 (IC 95% 1.67-5.25; P < 0.0001), and under the Log additive model an OR = 2.52 (IC 95% 1.54-4.15; P < 0.0001). Conclusions. The Arg389Gly polymorphism of the ADRB1 gene may be a worthy biological marker to predict the risk of developing cardiovascular diseases given a high-risk atherogenic index.