Single nucleotide polymorphisms in long noncoding RNA, ANRIL, are not associated with severe periodontitis but with adverse cardiovascular events among patients with cardiovascular disease

Effect of single nucleotide polymorphisms on the structure of long noncoding RNAs and their interaction with RNA binding proteins

Long non-coding RNAs (lncRNA) are emerging as a new class of regulatory RNAs with remarkable potential to be utilized as therapeutic targets against many human diseases. Several genome-wide association studies (GWAS) have catalogued Single Nucleotide Polymorphisms (SNPs) present in the noncoding regions of the genome from where lncRNAs originate. In this study, we have selected 67 lncRNAs with GWAS-tagged SNPs and have also investigated their role in affecting the local secondary structures. Majority of the SNPs lead to changes in the secondary structure of lncRNAs to a different extent by altering the base pairing patterns. These structural changes in lncRNA are also manifested in form of alteration in the binding site for RNA binding proteins (RBPs) along with affecting their binding efficacies. Ultimately, these structural modifications may influence the transcriptional and post-transcriptional pathways of these RNAs, leading to the causation of diseases. Hence, it is important to understand the possible underlying mechanism of RBPs in association with GWAS-tagged SNPs in human diseases.

The roles of ANRIL polymorphisms in periodontitis: a systematic review and meta-analysis

OBJECTIVES

The aim of this study is to investigate the potential role of ANRIL polymorphisms in susceptibility to periodontitis.

METHODS

The authors searched Pubmed, Web of Science, and Scopus up to April 2021 to identify all published studies without any language restriction on the association between ANRIL and periodontitis. A meta-analysis of all ANRIL variants replicated by three or more studies was performed by testing multiple genetic models of association. Pooled odds ratios and 95% confidence intervals (CI) were used to estimate associations. Tests for sensitivity and publication bias were performed.

RESULTS

Twenty-two variants in the ANRIL gene were examined for their potential association with the risk of periodontitis. However, only 4 (rs1333048, rs1333042, rs2891168, rs496892) are replicated at least three or more studies. The ANRIL rs1333048 was the most replicated polymorphisms with five articles, seven different populations comprising of 1331 cases, and 2624 controls. The pooled overall analysis showed that rs1333048, rs1333042, rs2891168, and rs496892 polymorphisms were associated with susceptibility to periodontitis in the whole population in allele contrast and dominant models. Moreover, similar to the overall analysis, rs1333048 polymorphism showed a significant association with grade C periodontitis (known as aggressive periodontitis in 1999 classification) in allele contrast (OR = 1.16) and dominant models (1.19). Interestingly, subgroup analysis also showed rs1333048 polymorphism might influence predisposition to a slowly progressive form of periodontitis (known as chronic periodontitis in 1999 classification).

CONCLUSION

Our findings suggest that the ANRIL rs1333048, rs1333042, rs2891168, and rs496892 polymorphisms might influence predisposition to periodontitis, particularly in Caucasians.

CLINICAL SIGNIFICANCE

ANRIL gene may represent a potential risk marker for periodontitis.

Long non-coding RNAs: Emerging roles in periodontitis

Periodontitis is a major burden of public health, affecting 20%-50% of the global population. It is a complex inflammatory disease characterized by the destruction of supporting structures of the teeth, leading to tooth loss and the emergence or worsening of systematic diseases. Understanding the molecular mechanisms underlying the physiopathology of periodontitis is beneficial for targeted therapeutics. Long non-coding RNAs (lncRNAs), transcripts made up of more than 200 nucleotides, have emerged as novel regulators of many biological and pathological processes. Recently, an increasing number of dysregulated lncRNAs have been found to be implicated in periodontitis. In this review, an overview of lncRNAs, including their biogenesis, characteristics, function mechanisms and research approaches, is provided. And we summarize recent research reports on the emerging roles of lncRNAs in regulating proliferation, apoptosis, inflammatory responses, and osteogenesis of periodontal cells to elucidate lncRNAs related physiopathology of periodontitis. Furthermore, we have highlighted the underlying mechanisms of lncRNAs in periodontitis pathology by interacting with microRNAs. Finally, the potential clinical applications, current challenges, and prospects of lncRNAs as diagnostic and prognostic biomarkers and therapeutic targets for periodontitis disease are discussed.

Automatic text-mining as an unbiased approach to uncover molecular associations between periodontitis and coronary artery disease

The increasing prevalence of periodontal and cardiovascular diseases is the result of a sedentary lifestyle associated with poor diet, obesity, hypercholesterolaemia, smoking habits, alcohol consumption and stress. The present study aims to uncover molecular associations between periodontitis and coronary heart disease using an unbiased strategy of automatic text mining traditionally applied to bibliometric studies. A total of 1590 articles on these diseases were retrieved from the Web of knowledge database and searched using the VOS viewer to create a network of keywords associated with both diseases. These data were supplemented with data from DisGeNET, which stores known associations to either periodontitis or coronary heart disease. Overall, the automated text mining approach presented here highlighted inflammatory molecules as common associations between periodontitis and coronary heart disease. Specifically, this study showed that molecules such as C-reactive protein, interleukins 6 and 1-β, myeloperoxidase, and matrix metalloproteinase 9 are simultaneously associated with periodontitis and coronary artery disease by both text mining and DisGeNET analyses. This association validates the multiplex assessment of salivary inflammatory markers as a tool to assess cardiovascular disease risk and could become an important tool to identify common molecular targets to monitor both diseases simultaneously. In addition, the text mining protocol and subsequent data processing and methods using bioinformatics tools could be useful to uncover links between other diseases.

Periodontal diseases and association with atherosclerotic disease

Cardiovascular diseases still account for the majority of deaths worldwide, although significant improvements in survival, after being affected by cardiovascular disease, have been achieved in the last decades. Periodontal diseases are also a common global burden. Several studies have shown a link between cardiovascular disease and periodontitis, although evidence is still lacking regarding the direct cause-effect relation. During the 2012 "Periodontitis and systemic diseases" workshop, the available evidence on the association between cardiovascular and periodontal diseases was discussed, covering biologic plausibility and clinical studies. The objective of the present narrative review was to update the previous reviews presented at the 2012 workshop, following similar methodological approaches, aiming to critically assess the available evidence. With regard to biologic plausibility, two aspects were reviewed: (a) for microbiologic mechanisms, assessing periodontal bacteria as a contributing factor to atherosclerosis based on seven "proofs," substantial evidence was found for Proofs 1 through 6, but not for Proof 7 (periodontal bacteria obtained from human atheromas can cause atherosclerosis in animal models), concluding that periodontal pathogens can contribute to atherosclerosis; (b) mechanistic studies, addressing five different inflammatory pathways that could explain the links between periodontitis and cardiovascular disease with the addition of some extra pathways , suggest an association between both entities, based on the presence of higher levels of these inflammatory markers in patients with periodontitis and cardiovascular disease, vs healthy controls, as well as on the evidence that periodontal treatment reduces serum levels of these mediators. When evidence from clinical studies was analyzed, two aspects were covered: (a) epidemiologic studies support the estimation that the incidence of atherosclerotic disease is higher in individuals with periodontitis than in individuals with no reported periodontitis, irrespective of many common risk factors, but with a substantial variability in the definitions used in reporting of exposure to periodontal diseases in different studies; (b) intervention trials have shown that periodontal therapy can reduce serum inflammatory mediators, improve the lipids profile, and induce positive changes in other cardiovascular disease surrogate measures, but no evidence is available to support that adequate periodontal therapy is able to reduce the risk for cardiovascular diseases, or the incidence of cardiovascular disease events in periodontitis patients.

Emerging role of long non-coding RNAs in the pathogenesis of periodontitis

Periodontitis is a bacteria-related chronic immune-associated condition that destructs bone and connective tissues around teeth. With a high incidence rate, it is regarded as a condition that impose substantial health burden. About half of the variance in the severity of periodontitis is attributed to genetic factors. Long non-coding RNAs (lncRNAs) have crucial roles in the development of several disorders such as periodontitis. A number of studies have reported dysregulation of lncRNAs such as UCA1, ANRIL, FGD5-AS1, NEAT1, FAS-AS1, Linc-RAM and NKILA in gingival tissues or blood samples of patients with periodontitis in comparison with healthy subjects. Moreover, several single nucleotide polymorphisms within lncRNAs have been associated with the susceptibility to this disorder. In the current review, we discuss the most recent articles about the role of lncRNAs in the pathogenesis of periodontitis.

The correlation of serum long non-coding RNA ANRIL with risk factors, functional outcome, and prognosis in atrial fibrillation patients with ischemic stroke

Background

This study aimed to evaluate the predictive value of long non‐coding RNA (lncRNA) antisense non‐coding RNA in the INK4 locus (ANRIL) for atrial fibrillation (AF) patients with ischemic stroke and investigate its correlation with risk factors, functional outcome, and prognosis.

Methods

A total of 386 consecutive AF patients were recruited. AF patients were followed up for 24‐48 months by outpatient follow‐up, telephone follow‐up, and medical record. The time of ischemic stroke in patients with AF was recorded, and follow‐up was continued for 6 months. LncRNA ANRIL expression from serum was detected by quantitative real‐time polymerase chain reaction (qRT‐PCR).

Results

Compared with the AF with ischemic stroke group (14.3 ± 2.3), patients in the AF without ischemic stroke group (11.9 ± 1.8) had significantly lower serum lncRNA ANRIL levels (P < .05). The sensitivity and specificity of lncRNA ANRIL for identifying AF with ischemic stroke were 76.6% and 81.4%, respectively. Spearman correlation analysis results shown that lncRNA ANRIL was significantly correlated with the NIHSS score (r_Spearman = .490, P < .001) and the mRS score (r_Spearman = .466, P < .001). Compared with the lncRNA ANRIL high‐expression group, the recurrence‐free survival (RFS) of the lncRNA ANRIL low‐expression group was significantly higher (χ² = 11.009, log‐rank P < .001). Cox proportional regression model analysis indicated that the serum lncRNA ANRIL level (P = .004), NIHSS score (P = .001), infarct volume (P = .035), and smoking (P < .001) were the risk factors for AF with ischemic stroke.

Conclusion

Serum lncRNA ANRIL exerts a good predictive value for AF with ischemic stroke, and its increased expression is correlated with worse RFS for patients.

Periodontitis and Tooth Loss Have Negative Systemic Impact on Circulating Progenitor Cell Levels: A Clinical Study

The aim of the present study was to investigate the association and impact of periodontitis and tooth loss on a subtype of endothelial progenitor cell (EPC) levels (CD133+/KDR+). Furthermore, the objective was to determine if the periodontal status influenced CD133+/KDR+ levels. In all, 88 patients with periodontitis and 79 healthy controls (HCs) were enrolled in the study. Enrolled patients were examined and characterized by clinical and blood sample analysis. Spearman's correlation test was applied in order to assess the interdependence between CD133+/KDR+ levels and all periodontal parameters. In order to estimate a statistically significant trend (p-trend) for ordered CD133++/KDR+ quartiles, the Jonckheere-Terpstra test was applied for all variables. Patients in the periodontitis group presented significantly lower CD133+/KDR+ levels (66.4 (45.5-269.6 cells/µL)) compared to the HC group (76.7 (24.3-313.2 cells/µL), p < 0.001). Lower CD133+/KDR+ levels negatively correlated with C-reactive protein (CRP), with the number of teeth, and with all periodontal parameters (p < 0.001). Moreover, there was a proportional increase in CD133+/KDR+ levels with a progressive increase in number of teeth (p-trend < 0.001), while there was a proportional decrease in CD133+/KDR+ levels with a proportional increase in clinical attachment level (CAL, p-trend = 0.003), probing depth (PD, p-trend = 0.007), and bleeding sites (bleeding on probing (BOP), p-trend < 0.001) as an extent measure of periodontitis. This study demonstrated that patients with periodontitis presented significantly lower CD133+/KDR+ levels compared to HCs. Moreover, all patients presented an increase in the CD133+/KDR+ EPC levels with an extended level of periodontitis and tooth loss.

lncRNA ANRIL protects H9c2 cells against hypoxia-induced injury through targeting the miR-7-5p/SIRT1 axis

BACKGROUND

Acute myocardial infarction (AMI) occurred in the heart, which underwent long-term ischemia, and was mainly caused by hypoxia. Recently, studies have uncovered the participation of long noncoding RNAs (lncRNAs) in the pathogenesis of heart disease. Here, we planned to probe the role and molecular basis of ANRIL in hypoxia-induced H9c2 cell injury.

METHODS

Trypan blue exclusion assay and Transwell and flow cytometry assays were conducted to assess hypoxia-induced injury by determining the viability, migration, invasion, and apoptosis of H9c2 cells in different conditions, respectively. Gene expressions were evaluated by quantitative real-time polymerase chain reaction or western blot analysis as needed. RNA immunoprecipitation and luciferase reporter assays were applied to confirm the associations among genes.

RESULTS

ANRIL expression was dramatically enhanced in hypoxia-injured H9c2 cells, and silencing ANRIL aggravated hypoxia-induced H9c2 cell injury. ANRIL positively regulated sirtuin 1 (SIRT1) expression via competitively binding with miR-7-5p. Moreover, inhibition of miR-7-5p counteracted ANRIL depletion-exacerbated injury in hypoxic H9c2 cells, meanwhile, forced SIRT1 expression attenuated the injury-promoting effect of miR-7-5p upregulation on hypoxic H9c2 cells.

CONCLUSION

Our findings disclosed that ANRIL plays a protective part in hypoxia-induced H9c2 cell injury via modulating the miR-7-5p/SIRT1 axis, suggesting the great potential of ANRIL as a protective target for AMI.

Mechanisms of Antisense Transcription Initiation with Implications in Gene Expression, Genomic Integrity and Disease Pathogenesis

Non-coding antisense transcripts arise from the strand opposite the sense strand. Over 70% of the human genome generates non-coding antisense transcripts while less than 2% of the genome codes for proteins. Antisense transcripts and/or the act of antisense transcription regulate gene expression and genome integrity by interfering with sense transcription and modulating histone modifications or DNA methylation. Hence, they have significant pathological and physiological relevance. Indeed, antisense transcripts were found to be associated with various diseases including cancer, diabetes, cardiac and neurodegenerative disorders, and, thus, have promising potentials for prognostic and diagnostic markers and therapeutic development. However, it is not clearly understood how antisense transcription is initiated and epigenetically regulated. Such knowledge would provide new insights into the regulation of antisense transcription, and hence disease pathogenesis with therapeutic development. The recent studies on antisense transcription initiation and its epigenetic regulation, which are limited, are discussed here. Furthermore, we concisely describe how antisense transcription/transcripts regulate gene expression and genome integrity with implications in disease pathogenesis and therapeutic development.

Angiogenic lncRNAs: A potential therapeutic target for ischaemic heart disease

Long noncoding RNAs (LncRNAs) are involved in biological processes and the pathology of diseases and represent an important biomarker or therapeutic target for disease. Emerging evidence has suggested that lncRNAs modulate angiogenesis by regulating the angiogenic cell process-including vascular endothelial cells (VECs); stem cells, particularly bone marrow-derived stem cells, endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs); and vascular smooth muscle cells (VSMCs)-and participating in ischaemic heart disease (IHD). Therapeutic angiogenesis as an alternative therapy to promote coronary collateral circulation has been demonstrated to significantly improve the prognosis and quality of life of patients with IHD in past decades. Therefore, lncRNAs are likely to represent a novel therapeutic target for IHD through regulation of the angiogenesis process. This review summarizes the classification and functions of lncRNAs and their roles in regulating angiogenesis and in IHD, in the context of an overview of therapeutic angiogenesis in clinical trials.