Potential Biological Markers of Atrial Fibrillation: A Chance to Prevent Cryptogenic Stroke

Integrative Multi-Omics Analysis for Etiology Classification and Biomarker Discovery in Stroke: Advancing towards Precision Medicine

Recent advancements in high-throughput omics technologies have opened new avenues for investigating stroke at the molecular level and elucidating the intricate interactions among various molecular components. We present a novel approach for multi-omics data integration on knowledge graphs and have applied it to a stroke etiology classification task of 30 stroke patients through the integrative analysis of DNA methylation and mRNA, miRNA, and circRNA. This approach has demonstrated promising performance as compared to other existing single technology approaches.

Association between serum cholinesterase and the prevalence of atrial fibrillation in Chinese hypertensive population: a cross-sectional study

BACKGROUND

Atrial fibrillation (AF) is a very common arrhythmia with significant incidence rate and mortality. Several studies have shown a notable correlation between non-alcoholic fatty liver disease (NAFLD) and AF. It has been observed that serum cholinesterase (SChE) levels are elevated in individuals with fatty liver. However, the relationship between the SChE index and AF is still unclear. Therefore, the purpose of this study is to explore the association between the SChE index and the prevalence of AF in patients with hypertension.

METHOD

We collected cross-sectional data from January 2018 to April 2021 based on a retrospective study of cardiovascular disease. A total of 748 patients with hypertension were included, of whom 165 had AF. We used logistic regression models to test the relationship between SChE and the prevalence of AF in hypertensive patients.

RESULT

In hypertensive patients, the SChE index was significantly associated with AF (OR = 0.723, P < 0.001). After adjusting for potential confounding factors, this correlation was still significant (OR = 0.778, P < 0.001). The stability of the model was verified by adjusting the variable type of SChE. The data were further stratified according to whether the patient had fatty liver. In the stratified data, the correlation between SChE and atrial fibrillation was still significant (P < 0.05).

CONCLUSION

Our study showed that SChE was significantly negatively correlated with the occurrence of AF in patients with hypertension. And this correlation was not affected by whether the patient had fatty liver.

Construction of a novel circRNA-miRNA-ferroptosis related mRNA network in ischemic stroke

Molecule alterations are important to explore the pathological mechanism of ischemic stroke (IS). Ferroptosis, a newly recognized type of regulated cell death, is related to IS. Identification of the interactions between circular RNA (circRNA), microRNA (miRNA) and ferroptosis related mRNA may be useful to understand the molecular mechanism of IS. The circRNA, miRNA and mRNA transcriptome data in IS, downloaded from the Gene Expression Omnibus (GEO) database, was used for differential expression analysis. Ferroptosis related mRNAs were identified from the FerrDb database, followed by construction of circRNA-miRNA-ferroptosis related mRNA network. Enrichment and protein-protein interaction analysis of mRNAs in circRNA-miRNA-mRNA network was performed, followed by expression validation by reverse transcriptase polymerase chain reaction and online dataset. A total of 694, 41 and 104 differentially expressed circRNAs, miRNAs and mRNAs were respectively identified in IS. Among which, dual specificity phosphatase 1 (DUSP1), nuclear receptor coactivator 4 (NCOA4) and solute carrier family 2 member 3 (SLC2A3) were the only three up-regulated ferroptosis related mRNAs. Moreover, DUSP1, NCOA4 and SLC2A3 were significantly up-regulated in IS after 3, 5 and 24 h of the attack. Based on these three ferroptosis related mRNAs, 4 circRNA-miRNA-ferroptosis related mRNA regulatory relationship pairs were identified in IS, including hsa_circ_0071036/hsa_circ_0039365/hsa_circ_0079347/hsa_circ_0008857-hsa-miR-122-5p-DUSP1, hsa_circ_0067717/hsa_circ_0003956/hsa_circ_0013729-hsa-miR-4446-3p-SLC2A3, hsa_circ_0059347/hsa_circ_0001414/hsa_circ_0049637-hsa-miR-885-3p-SLC2A3, and hsa_circ_0005633/hsa_circ_0004479-hsa-miR-4435-NCOA4. In addition, DUSP1 is involved in the signaling pathway of fluid shear stress and atherosclerosis. Relationship of regulatory action between circRNAs, miRNAs and ferroptosis related mRNAs may be associated with the development of IS.

Circular RNA CircPDS5B impairs angiogenesis following ischemic stroke through its interaction with hnRNPL to inactivate VEGF-A

BACKGROUND

Ischemic stroke (IS) is the primary cause of mortality and disability worldwide. Circular RNAs (circRNAs) have been proposed as crucial regulators in IS. This study focused on the role of circPDS5B in IS and its underlying mechanism.

METHOD

Transient middle cerebral artery occlusion (tMCAO) mice and glucose deprivation/reoxygenation (OGD/R)-exposed human brain microvascular endothelial cells (BMECs) were used as IS models. Expression levels of circPDS5B, heterogenous nuclear ribonucleoprotein L (hnRNPL), runt-related transcription factor-1 (Runx1), and Zinc finger protein 24 (ZNF24) were quantified by qRT-PCR. MTT, wound healing, transwell and tube formation assays were employed to evaluate the cell proliferation, migration, and angiogenesis, respectively. Moreover, RNA pull-down, and RIP assay were performed to investigate the interaction among circPDS5B, hnRNPL and vascular endothelial growth factor-A (VEGFA).

RESULTS

circPDS5B was significantly up-regulated in IS patients and tMCAO mice. Deficiency of circPDS5B relieved brain infarction and neuronal injury of tMCAO mice. OGD/R-induced apoptosis, inhibition in viability, migration, and angiogenesis in BMECs were dramatically abrogated by circPDS5B knockdown. Mechanistically, circPDS5B stabilized Runx1 and ZNF24 via recruiting hnRNPL, thereby suppressing the transcription and expression of VEGFA. hnRNPL silencing strengthened circPDS5B knockdown-mediated beneficial effect on IS.

CONCLUSION

Altogether, our study showed that high expression of circPDS5B exacerbated IS through recruitment of hnRNP to stabilize Runx1/ZNF24 and subsequently inactivate VEGF-A. Our findings suggest circPDS5B may be a novel therapeutic target for IS.

CircNUFIP2 overexpression induces GDF11 to ameliorate oxygen-glucose deprivation-induced hippocampal neuron cell apoptosis and oxidative stress after cerebral ischemia

Background Previous data have indicated the regulation of circular RNA (circRNA) toward cerebral ischemia. This study aims to reveal the effects of circNUFIP2 on cerebral ischemia and the underlying mechanism. Methods Oxygen-glucose deprivation (OGD) hippocampal neuron (HT22) cell model and middle cerebral artery occlusion (MCAO) mouse model were used for this study. The expression of circRNA nuclear FMR1 interacting protein 2 (circNUFIP2), microRNA-1224-5p (miR-1224-5p) and growth differentiation factor 11 (GDF11) was detected by quantitative real-time polymerase-chain reaction. Protein expression was checked by Western blotting. The binding relationships among circNUFIP2, miR-1224-5p and GDF11 were identified by dual-luciferase reporter assay, RNA pull-down assay, and RNA immunoprecipitation assay. Cell proliferation and apoptosis were investigated by 5-Ethynyl-29-deoxyuridine and flow cytometry analysis, respectively. Results CircNUFIP2 and GDF11 expression were decreased, but miR-1224-5p was increased in OGD-treated HT22 cells when compared with their expression in control groups. OGD treatment inhibited HT22 cell proliferation but induced cell apoptosis and oxidative stress; however, these effects were attenuated after circNUFIP2 overexpression. Also, circNUFIP2 upregulation assuaged the cerebral infarction of MCAO mice. Besides, circNUFIP2 bound to miR-1224-5p and mediated OGD-induced HT22 cell damage through miR-1224-5p. Meanwhile, knockdown of GDF11, a target gene of miR-1224-5p, relieved miR-1224-5p depletion-caused effects in OGD-treated HT22 cells. Furthermore, circNUFIP2 regulated GDF11 expression by interacting with miR-1224-5p. Conclusion CircNUFIP2 overexpression protected neuron cells against cerebral ischemia-induced damage, at least in part, by the miR-1224-5p/GDF11 pathway, providing a possible target for the therapy of cerebral ischemic stroke.

Association of Left Atrial Structure and Function With Cognitive Function in Adults With Metabolic Syndrome

Atrial fibrillation has been associated with cognitive impairment. Whether subclinical abnormalities in atrial function and substrate predisposing to atrial fibrillation impact cognitive function has received limited attention. We tested associations of echocardiographic markers of atrial structure and function with cognitive function and decrease in 510 participants with obesity and metabolic syndrome (mean age SD of 64.4 [5.2] years in men and 66.5 [3.9] years in women). Left atrial (LA) markers (volume index, emptying fraction, strain, function index, and stiffness index) were estimated based on transthoracic echocardiography. General cognitive functioning (Mini-mental state examination), verbal ability (verbal fluency test), memory and attention (Digit Span Tests), and processing speed and executive function (Trail-Making Tests A and B) were assessed at baseline and at 2-year follow-up. Multiple linear regression was used to test associations of atrial markers (modeled in SD units) with baseline and 2-year changes in cognitive scores adjusted for demographic and health covariates. LA structure and function were not associated with cognitive function at baseline. Larger LA volume index (standardized β [95% confidence interval] -0.13 [-0.22 to -0.03]), lower peak longitudinal strain (-0.11 [-0.20 to -0.01]), and higher stiffness index (-0.18 [-0.28 to -0.08]) were associated with 2-year worsening in Trail-Making Test A. Strain measurements were also associated with a 2-year change in the Controlled Oral Word Association Test. In conclusion, overall, adverse markers of LA structure and function were associated with 2-year detrimental executive function-related cognitive changes in a sample of participants at high risk for cardiovascular disease, highlighting LA substrate as a potential risk factor for cognitive decrease and dementia.

Profile and Functional Prediction of Plasma Exosome-Derived CircRNAs From Acute Ischemic Stroke Patients

Stroke is one of the major causes of death and long-term disability, of which acute ischemic stroke (AIS) is the most common type. Although circular RNA (circRNA) expression profiles of AIS patients have been reported to be significantly altered in blood and peripheral blood mononuclear cells, the role of exosome-containing circRNAs after AIS is still unknown. Plasma exosomes from 10 AIS patients and 10 controls were isolated, and through microarray and bioinformatics analysis, the profile and putative function of circRNAs in the plasma exosomes were studied. A total of 198 circRNAs were differentially quantified (|log2 fold change| ≥ 1.00, p < 0.05) between AIS patients and controls. The levels of 12 candidate circRNAs were verified by qRT-PCR, and the quantities of 10 of these circRNAs were consistent with the data of microarray. The functions of host genes of differentially quantified circRNAs, including RNA and protein process, focal adhesion, and leukocyte transendothelial migration, were associated with the development of AIS. As a miRNA sponge, differentially quantified circRNAs had the potential to regulate pathways related to AIS, like PI3K-Akt, AMPK, and chemokine pathways. Of 198 differentially quantified circRNAs, 96 circRNAs possessing a strong translational ability could affect cellular structure and activity, like focal adhesion, tight junction, and endocytosis. Most differentially quantified circRNAs were predicted to bind to EIF4A3 and AGO2—two RNA-binding proteins (RBPs)—and to play a role in AIS. Moreover, four of ten circRNAs with verified levels by qRT-PCR (hsa_circ_0112036, hsa_circ_0066867, hsa_circ_0093708, and hsa_circ_0041685) were predicted to participate in processes of AIS, including PI3K-Akt, AMPK, and chemokine pathways as well as endocytosis, and to be potentially useful as diagnostic biomarkers for AIS. In conclusion, plasma exosome-derived circRNAs were significantly differentially quantified between AIS patients and controls and participated in the occurrence and progression of AIS by sponging miRNA/RBPs or translating into proteins, indicating that circRNAs from plasma exosomes could be crucial molecules in the pathogenesis of AIS and promising candidates as diagnostic biomarkers and therapeutic targets for the condition.

Evaluation of atrial fibrosis in atrial fibrillation patients with three different methods

BACKGROUND

The presence of atrial fibrosis has already been known as a risk factor for atrial fibrillation (AF) development. We aimed to evaluate atrial fibrosis with previously defined three different methods, which were cardiac magnetic resonance imaging (C-MRI), echocardiographic strain imaging, and biomarkers and show the relationship between these methods in patients with AF scheduled for cryoballoon ablation.

METHODS

A total of 30 patients were enrolled. Atrial T1 relaxation durations were measured using C-MRI before the procedure of atrial fibrillation catheter ablation. Fibroblast growth factor-21 (FGF-21) and fibroblast growth factor-23 (FGF-23) levels were measured at serum derived from the femoral artery (Peripheral FGF 21 and 23) and left atrium blood samples (Central FGF 21 and 23) before catheter ablation. Preprocedural transthoracic echocardiography was performed. The median follow-up duration for atrial tachyarrhythmia (ATa) recurrence was 13 (12-18 months) months.

RESULTS

The mean ages of the study group were 55.23 ± 12.37 years, and there were 17 (56.7%) female patients in study population. There were negative correlations between post contrast T1 relaxation durations of both posterior and posterosuperior atrium, and central FGF-23 (r: - 0.561; p = 0.003; r:-0.624; p = 0.001; Posterior T1 vs. central FGF-23 levels and Posterosuperior T1 vs central FGF-23 levels, respectively). The positive correlations were observed between postcontrast posterior T1 relaxation durations and left ventricle ejection fraction (r:0.671; p = 0.001); left atrial emptying fraction (r:0.482; p = 0.013); peak atrial longitudinal strain (r:0.605; p = 0.001), and peak atrial contraction strain (r:0.604; p = 0.001). Also negative correlation was observed between postcontrast posterior T1 relaxation durations, and left atrial volume index (r: - 0.467; p = 0.016).

Circular RNA expression profile in blood according to ischemic stroke etiology

Background

The discovery of novel biomarkers of stroke etiology would be most helpful in management of acute ischemic stroke patients. Recently, circular RNAs (circRNAs) have been proposed as candidate biomarkers of neurological conditions due to its high stability. circRNAs function as sponges, sequestering miRNAs and are involved in most relevant biological functions. Our aim was to identify differentially expressed circRNAs in acute ischemic stroke patients according to stroke etiology.

Methods

A comprehensive expression profile of blood circRNAs was conducted by Arraystar Human circRNA arrays (13,617 probes) on a discovery cohort of 30 stroke patients with different stroke etiologies by TOAST classification. Real-time quantitative PCR (RT-qPCR) was used to validate array results in a cohort of 50 stroke patients. Functional in silico analysis was performed to identify potential interactions with microRNAs (miRNAs) and pathways underlying deregulated circRNAs.

Results

A set of 60 circRNAs were found to be upregulated in atherotrombotic versus cardioembolic strokes (fold-change > = 1.5 and p-value ≤ 0.05). Differential expression of hsa_circRNA_102488, originated from UBA52 gene, was replicated in the validation cohort. RNA-binding proteins (RBPs) sites of hsa_circRNA_102488 clustered around AGO2 and FUS proteins. Further functional analysis revealed interactions between deregulated circRNAs and a set of miRNAs involved in stroke-related pathways, such as fatty acid biogenesis or lysine degradation.

Conclusion

Different stroke subtypes show specific profiles of circRNAs expression. circRNAs may serve as a new source of biomarkers of stroke etiology in acute ischemic stroke patients.

The potential role of inflammation in cryptogenic stroke

PURPOSE

The study aimed to identify biomarkers predictive of cryptogenic stroke in patients aged <65.

MATERIALS AND METHODS

We investigated 520 patients with ischemic stroke. Out of them we assigned 65 patients to the cryptogenic stroke group (age 54 (47-58), 42% male) and 36 without stroke to the control group (age 53 (47-58), 61% male). In all patients we assessed carotid intima-media thickness (cIMT) and the levels of biomarkers which might be involved in the underlying biological mechanism of ischemic stroke.

RESULTS

There were no differences between stroke and control groups in the levels of syndecan 4, resistin, leptin, low-density lipoprotein cholesterol, triglycerides, prothrombin time, or activated partial thromboplastin time. There was no statistically significant difference in cIMT between groups. The level of high-density lipoprotein cholesterol was statistically significantly lower in the cryptogenic stroke group than in the controls (1.1 mmol/L (0.95-1.46) vs 1.37 (1.19-1.6) p = 0.02). Patients in the stroke group had higher levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) (391 pg/ml (107-1249) vs 109 (46-236); p = 0.003), interleukin 6 (2.6 pg/ml (0.8-8.1) vs 0.7 (0.4-1.2) p = 0.002) and asymmetric dimethylarginine (ADMA) (0.44 μmol/L (0.39-0.55) vs 0.36 (0.32-0.4); p = 0.0002) than the control group. In the multivariate analysis Il-6 was the only biomarker statistically significant associated with the occurrence of cryptogenic stroke (odds ratio 1.918, 95% confidence interval 1.029-3.575; p = 0.04).

CONCLUSIONS

Endothelial dysfunction assessed by increased level of ADMA affects the inflammatory state in patients with cryptogenic stroke. Increase in the inflammatory cytokine IL-6 by 1 pg/ml almost doubles the risk of stroke.

Fibrinolysis: strategies to enhance the treatment of acute ischemic stroke

Stroke is a major cause of disability worldwide, and is the second leading cause of death after ischemic heart disease. Until recently, tissue-type plasminogen activator (t-PA) was the only treatment for acute ischemic stroke. If administered within 4.5 h of symptom onset, t-PA improves the outcome in stroke patients. Mechanical thrombectomy is now the preferred treatment for patients with acute ischemic stroke resulting from a large-artery occlusion in the anterior circulation. However, the widespread use of mechanical thrombectomy is limited by two factors. First, only ⁓ 10% of patients with acute ischemic stroke have a proximal large-artery occlusion in the anterior circulation and present early enough to undergo mechanical thrombectomy within 6 h; an additional 9-10% of patients presenting within the 6-24-h time window may also qualify for the procedure. Second, not all stroke centers have the resources or expertise to perform mechanical thrombectomy. Nonetheless, patients who present to hospitals where thrombectomy is not an option can receive intravenous t-PA, and those with qualifying anterior circulation strokes can then be transferred to tertiary stroke centers where thrombectomy is available. Therefore, despite the advances afforded by mechanical thrombectomy, there remains a need for treatments that improve the efficacy and safety of thrombolytic therapy. In this review, we discuss: (i) current treatment options for acute ischemic stroke; (ii) the mechanism of action of fibrinolytic agents; and (iii) potential strategies to manipulate the fibrinolytic system to promote endogenous fibrinolysis or to enhance the efficacy of fibrinolytic therapy.

High-Resolution Pulse Oximetry (HRPO): A Cost-Effective Tool in Screening for Obstructive Sleep Apnea (OSA) in Acute Stroke and Predicting Outcome

INTRODUCTION

Obstructive sleep apnea (OSA) is a well-known risk factor for stroke. This is attributed to multiple mechanisms such as endothelial dysfunction, atrial fibrillation, hypertension, and comorbid obesity. STOP questionnaire alone is unreliable to diagnose OSA and in-hospital sleep study is costly and can be technically challenging. We used high-resolution pulse oximetry (HRPO) to test the feasibility of screening for OSA and predicting outcome.

METHODS

Data from 115 stroke patients who underwent HRPO was collected including Oxygen desaturation index (ODI) <4%, pulse rate, arterial oxygen saturation (SaO₂), and time spent at SaO₂ saturation <88%. We also collected data on various confounders. The outcomes measured were NIHSS (National Institutes of Health Stroke Scale), mRS (modified Rankin Score) on discharge, and discharge disposition.

RESULTS

Overall 115 patients with valid HRPO data were included in the study. Mean age was 64±12years with 68% white, 22% black, and 10% Hispanic population. Of this cohort of 115 patients, 56% were males. Of the subjects enrolled 22 had atrial fibrillation, 27 had type 2 diabetes, 7 had resistant hypertension, and 7 had patient foramen ovale. Of the 115 patients, 75 patients were found to have ODI of >10 and the mean ODI was 29±30. The NIHSS on admission was 6.14±6.93 and on discharge was 4.46±4.59, mRS on discharge was 1.70±1.67 with 52% being discharged home, 43% to rehab, 2% nursing home, and 3% to long-term acute care facility. In this study, we show a strong association between atrial fibrillation and increasing ODI (P<.001, OR 1.01, CI 1.00-1.03). In addition, our study also shows an association between discharges outcome of rehab (more deficits leading to higher disability) versus discharge to home (lesser deficits) if ODI was ≤10 (P = 0.005, OR 3.76, CI 1.49-9.52).

CONCLUSIONS

Our study showed that there is a significant burden of OSA in acute stroke patients. ODI emerged as a predictor of atrial fibrillation and discharge disposition in our study. HRPO may be a cost-effective tool to screen and evaluate for OSA in acute stroke patients.

Galectin-3 in Atrial Fibrillation: Mechanisms and Therapeutic Implications

Maintenance of atrial fibrillation is a complex mechanism, including extensive electrical and structural remodeling of the atria which involves progressive fibrogenesis. Galectin-3 is a biomarker of fibrosis, and, thus, may be involved in atrial remodeling in atrial fibrillation patients. We review the role of galectin-3 in AF mechanisms and its potential therapeutic implications.