Role of epigenetic mechanisms regulated by enhancers and long noncoding RNAs in cardiovascular disease

Genetics and epigenetics of diabetes and its complications in India

Diabetes mellitus (DM) has become a significant health concern with an increasing rate of morbidity and mortality worldwide. India ranks second in the number of diabetes cases in the world. The increasing burden of DM can be explained by genetic predisposition of Indians to type 2 diabetes mellitus (T2DM) coupled with rapid urbanization and socio-economic development in the last 3 decades leading to drastic changes in lifestyle. Environment and lifestyle changes contribute to T2DM development by altering epigenetic processes such as DNA methylation, histone post-translational modifications, and long non-coding RNAs, all of which regulate chromatin structure and gene expression. Although the genetic predisposition of Indians to T2DM is well established, how environmental and genetic factors interact and lead to T2DM is not well understood. In this review, we discuss the prevalence of diabetes and its complications across different states in India and how various risk factors contribute to its pathogenesis. The review also highlights the role of genetic predisposition among the Indian population and epigenetic factors involved in the etiology of diabetes. Lastly, we review current treatments and emphasize the knowledge gap with respect to genetic and epigenetic factors in the Indian context. Further understanding of the genetic and epigenetic determinants will help in risk prediction and prevention as well as therapeutic interventions, which will improve the clinical management of diabetes and associated macro- and micro-vascular complications.

Cannabinoid enhancement of lncRNA MMP25-AS1/MMP25 interaction reduces neutrophil infiltration and intestinal epithelial injury in HIV/SIV infection

Intestinal epithelial barrier dysfunction, a hallmark of HIV/SIV infection, persists despite viral suppression by combination antiretroviral therapy (cART). Emerging evidence suggests a critical role for long noncoding RNAs (lncRNAs) in maintaining epithelial homeostasis. We simultaneously profiled lncRNA/mRNA expression exclusively in colonic epithelium (CE) of SIV-infected rhesus macaques (RMs) administered vehicle (VEH) or Δ-9-tetrahydrocannabinol (THC). Relative to controls, fewer lncRNAs were up- or downregulated in CE of THC/SIV compared with VEH/SIV RMs. Importantly, reciprocal expression of the natural antisense lncRNA MMP25-AS1 (up 2.3-fold) and its associated protein-coding gene MMP25 (attracts neutrophils by inactivating alpha-1 anti-trypsin/SERPINA1) (down 2.2-fold) was detected in CE of THC/SIV RMs. Computational analysis verified 2 perfectly matched complementary regions and an energetically stable (normalized binding free energy = -0.2626) MMP25-AS1/MMP25 duplex structure. MMP25-AS1 overexpression blocked IFN-γ-induced MMP25 mRNA and protein expression in vitro. Elevated MMP25 protein expression in CE of VEH/SIV but not THC/SIV RMs was associated with increased infiltration by myeloperoxidase/CD11b++ neutrophils (transendothelial migration) and epithelial CD47 (transepithelial migration) expression. Interestingly, THC administered in combination with cART increased MMP25-AS1 and reduced MMP25 mRNA/protein expression in jejunal epithelium of SIV-infected RMs. Our findings demonstrate that MMP25-AS1 is a potentially unique epigenetic regulator of MMP25 and that low-dose THC can reduce neutrophil infiltration and intestinal epithelial injury potentially by downregulating MMP25 expression through modulation of MMP25-AS1.

Epigenetic Mechanisms Involved in Inflammaging-Associated Hypertension

PURPOSE OF REVIEW

This review summarizes the involvement of inflammaging in vascular damage with focus on the epigenetic mechanisms by which inflammaging-induced hypertension is triggered.

RECENT FINDINGS

Inflammaging in hypertension is a complex condition associated with the production of inflammatory mediators by the immune cells, enhancement of oxidative stress, and tissue remodeling in vascular smooth muscle cells and endothelial cells. Cellular processes are numerous, including inflammasome assembly and cell senescence which may involve mitochondrial dysfunction, autophagy, DNA damage response, dysbiosis, and many others. More recently, a series of noncoding RNAs, mainly microRNAs, have been described as possessing epigenetic actions on the regulation of inflammasome-related hypertension, emerging as a promising therapeutic strategy. Although there are a variety of pharmacological agents that effectively regulate inflammaging-related hypertension, a deeper understanding of the epigenetic events behind the control of vessel deterioration is needed for the treatment or even to prevent the disease onset.

Diagnostic significance of serum FGD5-AS1 and its predictive value for the development of cardiovascular diseases in patients with type 2 diabetes

BACKGROUND

As a result of the continuous rise in the incidence of type 2 diabetes mellitus (T2DM), related cardiovascular diseases (CVDs) have been a main healthy burden worldwide. This study aimed to investigate the potential role of FGD5-AS1 as a biomarker for the diagnosis of T2DM and predicting cardiovascular complications in T2DM.

METHODS

Three hundred subjects were recruited in this study, including 100 T2DM patients without CVDs, 100 T2DM patients with CVDs as well as 100 healthy subjects. Plasma FGD5-AS1 level was quantified using RT-qPCR assay. The correlation of FGD5-AS1 level with other key variables was assessed using Pearson correlation analysis. ROC curve analysis was performed to evaluate the diagnostic value of FGD5-AS1 for T2DM and related CVDs. The effect of FGD5-AS1 on AC16 and HA-VSMCs was determined.

RESULTS

FGD5-AS1 level showed a stepwise decrease in individuals with T2DM and CVDs compared to healthy persons. FGD5-AS1 was associated with BMI, systolic blood pressure, diastolic blood pressure, fasting glucose, 2-h postprandial blood glucose, HbA1c, triglycerides, usCRP, and HDL-cholesterol. The ROC analysis indicated FGD5-AS1 had a significant overall predictive ability to diagnose T2DM, T2DM with CVDs, and the combination of both. FGD5-AS1 increases the growth but alleviates apoptosis and fibrosis of high glucose-induced AC16 cells. FGD5-AS1 attenuate the growth and calcification but induced apoptosis of high glucose-treated HA-VSMC cells.

CONCLUSIONS

These results suggest that FGD5-AS1 are associated with T2DM and measuring FGD5-AS1 could potentially contribute to T2DM screening and prediction for risk of cardiovascular complication.

Emerging Role of Long Non-Coding RNAs in Diabetic Vascular Complications

Chronic metabolic disorders such as obesity and diabetes are associated with accelerated rates of macrovascular and microvascular complications, which are leading causes of morbidity and mortality worldwide. Further understanding of the underlying molecular mechanisms can aid in the development of novel drug targets and therapies to manage these disorders more effectively. Long non-coding RNAs (lncRNAs) that do not have protein-coding potential are expressed in a tissue- and species-specific manner and regulate diverse biological processes. LncRNAs regulate gene expression in cis or in trans through various mechanisms, including interaction with chromatin-modifying proteins and other regulatory proteins and via posttranscriptional mechanisms, including acting as microRNA sponges or as host genes of microRNAs. Emerging evidence suggests that major pathological factors associated with diabetes such as high glucose, free fatty acids, proinflammatory cytokines, and growth factors can dysregulate lncRNAs in inflammatory, cardiac, vascular, and renal cells leading to altered expression of key inflammatory genes and fibrotic genes associated with diabetic vascular complications. Here we review recent reports on lncRNA characterization, functions, and mechanisms of action in diabetic vascular complications and translational approaches to target them. These advances can provide new insights into the lncRNA-dependent actions and mechanisms underlying diabetic vascular complications and uncover novel lncRNA-based biomarkers and therapies to reduce disease burden and mortality.

lncRNA DRAIR is downregulated in diabetic monocytes and modulates the inflammatory phenotype via epigenetic mechanisms

Long noncoding RNAs (lncRNAs) are increasingly implicated in the pathology of diabetic complications. Here, we examined the role of lncRNAs in monocyte dysfunction and inflammation associated with human type 2 diabetes mellitus (T2D). RNA sequencing analysis of CD14⁺ monocytes from patients with T2D versus healthy controls revealed downregulation of antiinflammatory and antiproliferative genes, along with several lncRNAs, including a potentially novel divergent lncRNA diabetes regulated antiinflammatory RNA (DRAIR) and its nearby gene CPEB2. High glucose and palmitic acid downregulated DRAIR in cultured CD14⁺ monocytes, whereas antiinflammatory cytokines and monocyte-to-macrophage differentiation upregulated DRAIR via KLF4 transcription factor. DRAIR overexpression increased antiinflammatory and macrophage differentiation genes but inhibited proinflammatory genes. Conversely, DRAIR knockdown attenuated antiinflammatory genes, promoted inflammatory responses, and inhibited phagocytosis. DRAIR regulated target gene expression through interaction with chromatin, as well as inhibition of the repressive epigenetic mark H3K9me2 and its corresponding methyltransferase G9a. Mouse orthologous Drair and Cpeb2 were also downregulated in peritoneal macrophages from T2D db/db mice, and Drair knockdown in nondiabetic mice enhanced proinflammatory genes in macrophages. Thus, DRAIR modulates the inflammatory phenotype of monocytes/macrophages via epigenetic mechanisms, and its downregulation in T2D may promote chronic inflammation. Augmentation of endogenous lncRNAs like DRAIR could serve as novel antiinflammatory therapies for diabetic complications.

Knockdown of lncRNA ENST00000609755.1 Confers Protection Against Early oxLDL-Induced Coronary Heart Disease

Background: This study investigated the association between long non-coding RNAs (lncRNAs) and coronary heart disease (CHD) and further elucidated the potential biological roles of lncRNAs in CHD pathogenesis.

Methods: A case-control study (590 patients and 590 controls) was conducted from February 2017 and March 2019 in Fuzhou, China. Environmental factors were investigated using questionnaires and physical examinations. Five representative lncRNAs were screened using lncRNA microarray (peripheral blood in 5 cases and 5 controls) and further verified by quantitative real-time polymerase chain reaction (peripheral blood leukocyte in 100 cases and 100 controls). Oxidized low-density lipoprotein (oxLDL) was used to induce a human coronary artery endothelial cell (HCAECs) injury model, and loss of function was used to elucidate the role of lncRNA ENST00000609755.1 (lnc-MICALL2-2) in oxLDL-induced HCAECs injury.

Results: A total of 320 lncRNAs were found dysregulated in CHD patients (fold change> 2, p < 0.05). The results of a discovery microarray, population verification and HCAEC experiments suggested the lnc-MICALL2-2 is upregulated in CHD subjects and in an oxLDL-induced HCAECs injury model. Conversely, lnc-MICALL2-2 inhibition in vitro attenuated the effects of oxLDL on HCAECs morphology, proliferation, and apoptosis.

Conclusion: Elevated expression of lnc-MICALL2-2 is an independent risk factor for CHD, and knockdown subsequently confers protection against early pathological processes of oxLDL-induced CHD.

Identification of susceptibility loci for cardiovascular disease in adults with hypertension, diabetes, and dyslipidemia

BACKGROUND

Hypertension (HTN), diabetes mellitus (DM), and dyslipidemia (DL) are well-known risk factors of cardiovascular disease (CVD), but not all patients develop CVDs. Studies have been limited investigating genetic risk of CVDs specific to individuals with metabolic diseases. This study aimed to identify disease-specific and/or common genetic loci associated with CVD susceptibility in chronic metabolic disease patients.

METHODS

We conducted a genome-wide association study (GWAS) of a multiple case-control design with data from the City Cohort within Health EXAminees subcohort of the Korean Genome and Epidemiology Study (KoGES_HEXA). KoGES_HEXA is a population-based prospective cohort of 173,357 urban Korean adults that had health examinations at medical centers. 42,393 participants (16,309 HTN; 5,314 DM; 20,770 DL) were analyzed, and each metabolic disease group was divided into three CVD case-controls: coronary artery disease (CAD), ischemic stroke (IS), and cardio-cerebrovascular disease (CCD). GWASs were conducted for each case-control group with 7,975,321 imputed single nucleotide polymorphisms using the Phase 3 Asian panel from 1000 Genomes Project, by logistic regression and controlled for confounding variables. Genome-wide significant levels were implemented to identify important susceptibility loci.

RESULTS

Totaling 42,393 individuals, this study included 16,309 HTN (mean age [SD], 57.28 [7.45]; 816 CAD, 398 IS, and 1,185 CCD cases), 5,314 DM (57.79 [7.39]; 361 CAD, 153 IS, and 497 CCD cases), and 20,770 DL patients (55.34 [7.63]; 768 CAD, 295 IS, and 1,039 CCD cases). Six genome-wide significant CVD risk loci were identified, with relatively large effect sizes: 1 locus in HTN (HTN-CAD: 17q25.3/CBX8-CBX4 [OR, 2.607; P = 6.37 × 10^-9]), 2 in DM (DM-IS: 4q32.3/MARCH1-LINC01207 [OR, 5.587; P = 1.34 × 10^-8], and DM-CCD: 17q25.3/RPTOR [OR, 3.511; P = 1.99 × 10^-8]), and 3 in DL (DL-CAD: 9q22.2/UNQ6494-LOC101927847 [OR, 2.282; P = 7.78 × 10^-9], DL-IS: 3p22.1/ULK4 [OR, 2.162; P = 2.97 × 10^-8], and DL-CCD: 2p22.2/CYP1B1-CYP1B1-AS1 [OR, 2.027; P = 4.24 × 10^-8]).

CONCLUSIONS

This study identified 6 susceptibility loci and positional candidate genes for CVDs in HTN, DM, and DL patients using an unprecedented study design. 1 locus (17q25.3) was commonly associated with CAD. These associations warrant validation in additional studies for potential therapeutic applications.

Epigenetic Mechanisms in Diabetic Vascular Complications and Metabolic Memory: The 2020 Edwin Bierman Award Lecture

Macrovascular complications such as atherosclerosis, myocardial infarction and stroke, and microvascular complications such as nephropathy, retinopathy, and neuropathy are the major causes of increased morbidity and mortality in both type 1 and type 2 diabetes. Increased inflammation, oxidative stress, and fibrosis are common features in most diabetes complications. Although extensive studies have examined the biochemical pathways leading to the expression of inflammatory, profibrotic, and other pathological genes, as well as genetic factors related to diabetes and associated complications, much less is known about the contribution of epigenetic changes that occur without alterations in the DNA sequence. Environmental factors, lifestyles, and improper diet implicated in diabetes can affect epigenetic states. Epigenetic modifications, including DNA methylation and histone modifications, can alter gene transcription in response to environmental stimuli and cooperate with noncoding RNAs. These epigenetic modifications have been observed in various target cells under diabetic conditions. Moreover, epigenetics has also been implicated in the phenomenon of metabolic memory observed in clinic trials and animal studies, in which prior episodes of poor glycemic control can confer continued risk of complications despite subsequent glucose normalization. Epigenome-wide association studies in cohorts with diabetes are uncovering epigenotype variations that provide new insights into diabetic vascular complications. Here, I discuss the role of epigenetics and noncoding RNAs in diabetes complications and metabolic memory, and their translation potential to serve as biomarkers and drug targets to improve clinical management of diabetic vascular complications.

Mitochondria at Work: New Insights into Regulation and Dysregulation of Cellular Energy Supply and Metabolism

Mitochondria are of great relevance to health, and their dysregulation is associated with major chronic diseases. Research on mitochondria-156 brand new publications from 2019 and 2020-have contributed to this review. Mitochondria have been fundamental for the evolution of complex organisms. As important and semi-autonomous organelles in cells, they can adapt their function to the needs of the respective organ. They can program their function to energy supply (e.g., to keep heart muscle cells going, life-long) or to metabolism (e.g., to support hepatocytes and liver function). The capacity of mitochondria to re-program between different options is important for all cell types that are capable of changing between a resting state and cell proliferation, such as stem cells and immune cells. Major chronic diseases are characterized by mitochondrial dysregulation. This will be exemplified by cardiovascular diseases, metabolic syndrome, neurodegenerative diseases, immune system disorders, and cancer. New strategies for intervention in chronic diseases will be presented. The tumor microenvironment can be considered a battlefield between cancer and immune defense, competing for energy supply and metabolism. Cancer cachexia is considered as a final stage of cancer progression. Nevertheless, the review will present an example of complete remission of cachexia via immune cell transfer. These findings should encourage studies along the lines of mitochondria, energy supply, and metabolism.