TWEAK/Fn14 mediates atrial-derived HL-1 myocytes hypertrophy via JAK2/STAT3 signalling pathway

Novel therapeutic targets for cardiorenal syndrome

Cardiorenal syndrome (CRS) is an interdependent dysfunction of the heart and kidneys, where failure in one organ precipitates failure in the other. The pathophysiology involves sustained renin-angiotensin-aldosterone-system (RAAS) activation, mitochondrial dysfunction, inflammation, fibrosis, oxidative stress and tissue remodeling, culminating in organ dysfunction. Existing therapies targeting the RAAS, diuretics and other agents have limitations, including diuretic resistance and compensatory sodium reabsorption. Therefore, there is a pressing need for novel druggable targets involved in CRS pathogenesis. This review addresses the challenges of existing treatments and emphasizes the importance of discovering new therapeutic targets. It highlights emerging targets such as Klotho, sex-determining region Y box 9 (SOX9), receptor-interacting protein kinase 3 (RIPK3), β-amino-isobutyric acid (BAIBA), thrombospondin-1 (TSP-1), among others, with their potential roles in CRS.

Novel Drug Targets for Atrial Fibrillation Identified Through Mendelian Randomization Analysis of the Blood Proteome

PURPOSE

Novel, effective, and safe preventive therapy targets for AF are still needed. Circulating proteins with causal genetic evidence are promising candidates. We aimed to systematically screen circulating proteins for AF drug targets and determine their safety and efficacy using genetic methods.

METHODS

The protein quantitative trait loci (pQTL) of up to 1949 circulating proteins were retrieved from nine large genome-proteome-wide association studies. Two-sample Mendelian Randomization (MR) and colocalization analyses were used to estimate the causal effects of proteins on the risk of AF. Furthermore, phenome-wide MR was conducted to depict side effects and the drug-target databases were searched for drug validation and repurposing.

RESULTS

Systematic MR screen identified 30 proteins as promising AF drug targets. Genetically predicted 12 proteins increased AF risk (TES, CFL2, MTHFD1, RAB1A, DUSP13, SRL, ANXA4, NEO1, FKBP7, SPON1, LPA, MANBA); 18 proteins decreased AF risk (PMVK, UBE2F, SYT11, CHMP3, PFKM, FBP1, TNFSF12, CTSZ, QSOX2, ALAD, EFEMP1, FLRT2, LRIG1, OLA1, SH3BGRL3, IL6R, B3GNT8, FCGR2A). DUSP13 and TNFSF12 possess strong colocalization evidence. For the proteins that were identified, extended phe-MR analysis was conducted to assess their side-effect profiles, while drug-target databases provided information on their approved or investigated indications.

CONCLUSION

We identified 30 circulating proteins as potential preventive targets for AF.

Fibroblast growth factor 5 as a target for atrial fibrillation treatment: Evidence from mendelian randomization

BACKGROUND

Previous studies have found that inflammatory proteins are involved in the pathogenesis of atrial fibrillation (AF). We used mendelian randomization to explore the potential pathogenic inflammatory proteins of AF.

METHODS

This study adopts a Mendelian randomization design to primarily assess causal associations using the Wald ratio and the inverse variance weighting method. It leverages protein quantitative trait locus (pQTL) data encompassing 91 types of inflammatory proteins from 14,824 participants of European ancestry. The primary analysis phase utilizes AF GWAS data from 55,106 participants, with an additional 237,690 participants included in the validation stage. Sensitivity analyses, including reverse causality analysis, Bayesian colocalization analysis, and phenotype scanning, were conducted. Finally, the study explores potential targeted drugs.

RESULTS

The findings highlight a causal link between 7 inflammatory proteins and AF, with 2 showing positive correlations and 5 exhibiting negative correlations. Among these, fibroblast growth factor 5 (FGF5) emerges as particularly robust in sensitivity analysis. Colocalization analysis indicates a shared genetic variation between FGF5 and AF, supporting its potential as a targeted therapy for AF. Importantly, this causal relationship remains unaffected by reverse causality. Furthermore, significant pleiotropic effects were observed in phenotype scanning. Finally, the causal association between FGF5 and AF was successfully replicated during the validation phase.

CONCLUSION

FGF5 may become an intervention target for AF targeted therapy.

Targeting the JAK2/STAT3 signaling pathway with natural plants and phytochemical ingredients: A novel therapeutic method for combatting cardiovascular diseases

The aim of this article is to introduce the roles and mechanisms of the JAK2/STAT3 pathway in various cardiovascular diseases, such as myocardial fibrosis, cardiac hypertrophy, atherosclerosis, myocardial infarction, and myocardial ischemiareperfusion. In addition, the effects of phytochemical ingredients and different natural plants, mainly traditional Chinese medicines, on the regulation of different cardiovascular diseases via the JAK2/STAT3 pathway are discussed. Surprisingly, the JAK2 pathway has dual roles in different cardiovascular diseases. Future research should focus on the dual regulatory effects of different phytochemical ingredients and natural plants on JAK2 to pave the way for their use in clinical trials.

Proteome-Wide Mendelian Randomization Analysis Identified Potential Drug Targets for Atrial Fibrillation

Background Finding effective and safe therapeutic drugs for atrial fibrillation (AF) is an important concern for clinicians. Proteome-wide Mendelian randomization analysis provides new ideas for finding potential drug targets. Methods and Results Using a proteome-wide Mendelian randomization approach, we assessed the genetic predictive causality between thousands of proteins and AF risk and found that genetically predicted plasma levels of phosphomevalonate kinase, tumor necrosis factor ligand superfamily member 12, sulfhydryl oxidase 2, interleukin-6 receptor subunit alpha, and low-affinity immunoglobulin gamma Fc region receptor II-b might decrease AF risk, while genetically predicted plasma levels of beta-mannosidase, collagen alpha-1(XV) chain, ANXA4 (annexin A4), COF2 (cofilin-2), and RAB1A (Ras-related protein Rab-1A) might increase AF risk (P<3.4×10-5). By using different Mendelian randomization methods and instrumental variable selection thresholds, we performed sensitivity analyses in 30 scenarios to test the robustness of positive findings. Replication analyses were also performed in independent samples to further avoid false-positive findings. Drugs targeting tumor necrosis factor ligand superfamily member 12, interleukin-6 receptor subunit alpha, low-affinity immunoglobulin gamma Fc region receptor II-b, and annexin A4 are approved or in development. The results of the phenome-wide Mendelian randomization analysis showed that changing the plasma levels of phosphomevalonate kinase, cofilin-2, annexin A4, Ras-related protein Rab-1A, sulfhydryl oxidase 2, and collagen alpha-1(XV) chain did not increase the risk of other diseases while decreasing the risk of AF. Conclusions We found a significant causal association between genetically predicted levels of 10 plasma proteins and AF risk. Four of these proteins have drugs targeting them that are approved or in development, and our results suggest the potential for these drugs to treat AF or cause AF. Sulfhydryl oxidase 2, low-affinity immunoglobulin gamma Fc region receptor II-b, and beta-mannosidase have not been suggested by previous laboratory or epidemiological studies to be associated with AF and may reveal new pathophysiological pathways as well as therapeutic targets for AF.

The Association Between Rheumatoid Arthritis and Atrial Fibrillation: Epidemiology, Pathophysiology and Management

Atrial fibrillation (AF) is the most common cardiac arrhythmia with a significant increase in morbidity and mortality worldwide. Rheumatoid arthritis (RA), as a systemic inflammatory disease, affecting 0.5-1.0% of the adult population, is associated with increased incidence of cardiac arrhythmias such as AF. Several epidemiologic studies find that the risk of AF is increased in RA when compared with the general population. Other studies are inconsistent. Considering that inflammation plays an important role in AF, RA may be involved in the occurrence and development of AF. This review summarizes the epidemiology, pathophysiology, and management of AF in patients with RA.

Relationship Between Circulating MicroRNAs and Left Ventricular Hypertrophy in Hypertensive Patients

Objective

Left ventricular hypertrophy (LVH) is a common complication of hypertension and microRNAs (miRNAs) are considered to play an important role in cardiac hypertrophy development. This study evaluated the relationship between circulating miRNAs and LVH in hypertensive patients.

Methods

Two cohorts [exploratory (n = 42) and validation (n = 297)] of hypertensive patients were evaluated by clinical, laboratory and echocardiography analysis. The serum expression of 754 miRNAs in the exploratory cohort and 6 miRNAs in the validation cohort was evaluated by the TaqMan OpenArray^® system and quantitative polymerase chain reaction, respectively.

Results

Among the 754 analyzed miRNAs, ten miRNAs (miR-30a-5p, miR-let7c, miR-92a, miR-451, miR-145-5p, miR-185, miR-338, miR-296, miR-375, and miR-10) had differential expression between individuals with and without LVH in the exploratory cohort. Results of multivariable regression analysis adjusted for confounding variables showed that three miRNAs (miR-145-5p, miR-451, and miR-let7c) were independently associated with LVH and left ventricular mass index in the validation cohort. Functional enrichment analysis demonstrated that these three miRNAs can regulate various genes and pathways related to cardiac remodeling. Furthermore, in vitro experiments using cardiac myocytes demonstrated that miR-145-5p mimic transfection up-regulated the expression of brain and atrial natriuretic peptide genes, which are markers of cardiac hypertrophy, while anti-miR-145-5p transfection abrogated the expression of these genes in response to norepinephrine stimulus.

Conclusions

Our data demonstrated that circulating levels of several miRNAs, in particular miR-145-5p, miR-451, and let7c, were associated with LVH in hypertensive patients, indicating that these miRNAS may be potential circulating biomarkers or involved in hypertension-induced LV remodeling.

TWEAK-Fn14 as a common pathway in the heart and the kidneys in cardiorenal syndrome

There is a complex relationship between cardiac and renal disease, often referred to as the cardiorenal syndrome. Heart failure adversely affects kidney function, and both acute and chronic kidney disease are associated with structural and functional changes to the myocardium. The pathological mechanisms and contributing interactions that surround this relationship remain poorly understood, limiting the opportunities for therapeutic intervention. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible 14 (Fn14), are abundantly expressed in injured kidneys and heart. The TWEAK-Fn14 axis promotes responses that drive tissue injury such as inflammation, proliferation, fibrosis, and apoptosis, while restraining the expression of tissue protective factors such as the anti-aging factor Klotho and the master regulator of mitochondrial biogenesis peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). High levels of TWEAK induce cardiac remodeling, and promote inflammation, tubular and podocyte injury and death, fibroblast proliferation, and, ultimately, renal fibrosis. Accordingly, targeting the TWEAK-Fn14 axis is protective in experimental kidney and heart disease. TWEAK has also emerged as a biomarker of kidney damage and cardiovascular outcomes and has been successfully targeted in clinical trials. In this review, we update our current knowledge of the roles of the TWEAK-Fn14 axis in cardiovascular and kidney disease and its potential contribution to the cardiorenal syndrome. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Maternal High Fat Diet and Diabetes Disrupts Transcriptomic Pathways That Regulate Cardiac Metabolism and Cell Fate in Newborn Rat Hearts

Background: Children born to diabetic or obese mothers have a higher risk of heart disease at birth and later in life. Using chromatin immunoprecipitation sequencing, we previously demonstrated that late-gestation diabetes, maternal high fat (HF) diet, and the combination causes distinct fuel-mediated epigenetic reprogramming of rat cardiac tissue during fetal cardiogenesis. The objective of the present study was to investigate the overall transcriptional signature of newborn offspring exposed to maternal diabetes and maternal H diet. Methods: Microarray gene expression profiling of hearts from diabetes exposed, HF diet exposed, and combination exposed newborn rats was compared to controls. Functional annotation, pathway and network analysis of differentially expressed genes were performed in combination exposed and control newborn rat hearts. Further downstream metabolic assessments included measurement of total and phosphorylated AKT2 and GSK3β, as well as quantification of glycolytic capacity by extracellular flux analysis and glycogen staining. Results: Transcriptional analysis identified significant fuel-mediated changes in offspring cardiac gene expression. Specifically, functional pathways analysis identified two key signaling cascades that were functionally prioritized in combination exposed offspring hearts: (1) downregulation of fibroblast growth factor (FGF) activated PI3K/AKT pathway and (2) upregulation of peroxisome proliferator-activated receptor gamma coactivator alpha (PGC1α) mitochondrial biogenesis signaling. Functional metabolic and histochemical assays supported these transcriptome changes, corroborating diabetes- and diet-induced cardiac transcriptome remodeling and cardiac metabolism in offspring. Conclusion: This study provides the first data accounting for the compounding effects of maternal hyperglycemia and hyperlipidemia on the developmental cardiac transcriptome, and elucidates nuanced and novel features of maternal diabetes and diet on regulation of heart health.

JLX001 improves myocardial ischemia-reperfusion injury by activating Jak2-Stat3 pathway

AIMS

To investigate the preclinical pharmacodynamics and mechanism of JLX001 against myocardial ischemia reperfusion (MI/R) for clinical application.

MATERIALS AND METHODS

In vivo, SD rats were given intragastric administration for 5 days, and the MI/R model was established by ligating/releasing the left anterior descending coronary artery. In vitro, the oxygen-glucose deprivation/reperfusion (OGD/R) model was established after the drug was pre-incubated for 24 h in H9C2 cells. The infract size was determined by TTC staining. Left ventricular function of MI/R rats was detected by echocardiography. The level of histopathological score was determined by hematoxylin-eosin (HE) staining. The level of superoxide dismutase (SOD), malondialdehyde (MDA), creatine kinase (CK), lactic dehydrogenase (LDH), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were determined by relevant kits. The level of apoptosis was measured by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and Hoechst staining. The expression of p-Jak2, p-Stat3, Bax, Bcl-2, TNF-α, IL-1β protein were determined by western blot.

KEY FINDINGS

JLX001 can significantly improve left ventricular function, reduce myocardial infract size, histopathological score, the level of MDA, CK, LDH, TNF-α, IL-1β and the expression of Bax protein, significantly increase the activity of SOD, Bcl-2 protein expression, p-Jak2 protein expression, p-Stat3 protein expression in rat heart tissues and H9C2 cells. These effects can be reversed by AG490 which is a specific inhibitor of Jak2-Stat3 pathway.

SIGNIFICANCE

JLX001 can alleviate MI/R injury by inhibiting myocardial apoptosis, inflammation, and oxidative stress via Jak2-Stat3 pathway in vivo and in vitro.

TWEAK/Fn14 axis in respiratory diseases

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a well known multifunctional cytokine extensively distributed in cell types and tissues. Accumulating evidence has shown that TWEAK binding to the receptor factor-inducible 14 (Fn14) participates in diverse pathologic processes including cell proliferation and death, angiogenesis, carcinogenesis and inflammation. Interestingly, alterations of intracellular signaling cascades are correlated to the development of respiratory disease. Recently, a several lines of evidence suggests that TWEAK in lung tissues are closely associated with these signaling pathways. In this review, we explore if TWEAK could provide a novel therapeutic strategy for managing respiratory disease in general and pulmonary arterial hypertension (PAH), obstructive sleep apnea syndrome (OSAS), asthma, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and non-small cell lung cancer (NSCLC), specifically.

Alteration of calcium signalling in cardiomyocyte induced by simulated microgravity and hypergravity

Objectives

Cardiac Ca²⁺ signalling plays an essential role in regulating excitation‐contraction coupling and cardiac remodelling. However, the response of cardiomyocytes to simulated microgravity and hypergravity and the effects on Ca²⁺ signalling remain unknown. Here, we elucidate the mechanisms underlying the proliferation and remodelling of HL‐1 cardiomyocytes subjected to rotation‐simulated microgravity and 4G hypergravity.

Materials and Methods

The cardiomyocyte cell line HL‐1 was used in this study. A clinostat and centrifuge were used to study the effects of microgravity and hypergravity, respectively, on cells. Calcium signalling was detected with laser scanning confocal microscopy. Protein and mRNA levels were detected by Western blotting and real‐time PCR, respectively. Wheat germ agglutinin (WGA) staining was used to analyse cell size.

Results

Our data showed that spontaneous calcium oscillations and cytosolic calcium concentration are both increased in HL‐1 cells after simulated microgravity and 4G hypergravity. Increased cytosolic calcium leads to activation of calmodulin‐dependent protein kinase II/histone deacetylase 4 (CaMKII/HDAC4) signalling and upregulation of the foetal genes ANP and BNP, indicating cardiac remodelling. WGA staining indicated that cell size was decreased following rotation‐simulated microgravity and increased following 4G hypergravity. Moreover, HL‐1 cell proliferation was increased significantly under hypergravity but not rotation‐simulated microgravity.

Conclusions

Our study demonstrates for the first time that Ca²⁺/CaMKII/HDAC4 signalling plays a pivotal role in myocardial remodelling under rotation‐simulated microgravity and hypergravity.

Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK)/Fibroblast Growth Factor-Inducible 14 (Fn14) Axis in Cardiovascular Diseases: Progress and Challenges

Cardiovascular diseases (CVD) are the leading cause of mortality in Western countries. CVD include several pathologies, such as coronary artery disease, stroke, peripheral artery disease, and aortic aneurysm, among others. All of them are characterized by a pathological vascular remodeling in which inflammation plays a key role. Interaction between different members of the tumor necrosis factor superfamily and their cognate receptors induce several biological actions that may participate in CVD. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its functional receptor, fibroblast growth factor-inducible 14 (Fn14), are abundantly expressed during pathological cardiovascular remodeling. The TWEAK/Fn14 axis controls a variety of cellular functions, such as proliferation, differentiation, and apoptosis, and has several biological functions, such as inflammation and fibrosis that are linked to CVD. It has been demonstrated that persistent TWEAK/Fn14 activation is involved in both vessel and heart remodeling associated with acute and chronic CVD. In this review, we summarized the role of the TWEAK/Fn14 axis during pathological cardiovascular remodeling, highlighting the cellular components and the signaling pathways that are involved in these processes.

Cryptotanshinone Attenuates Airway Remodeling by Inhibiting Crosstalk Between Tumor Necrosis Factor-Like Weak Inducer of Apoptosis and Transforming Growth Factor Beta 1 Signaling Pathways in Asthma

The study is to investigate the effect of cryptotanshinone (CTS) on airway remodeling and the possible mechanism. Male BALB/c mice were pretreated with CTS or dexamethasone 30 min before nebulized inhalation of ovalbumin (OVA). CTS significantly inhibited OVA-induced increases of eosinophils and neutrophils infiltration of bronchoalveolar lavage fluids (BALFs), reduced airway resistance in asthmatic mice, decreased the accumulation of inflammatory cells, the hyperplasia of goblet cells and the deposition of collagen in asthmatic mice lung tissue, as well as markedly attenuated the leakage of inflammatory cells and the level of OVA-specific immunoglobulin E in BALFs. CTS also inhibited the expressions of alpha-smooth muscle actin, tumor necrosis factor-like weak inducer of apoptosis (TWEAK), Fn14, transforming growth factor (TGF)-β1, Smad4, and phosphorylation of Smad2/3 and STAT3 (Tyr705). In comparison to TWEAK inhibitor or TWEAK small interfering RNA (siRNA), which were used to inhibit TWEAK/STAT3 signaling pathways, CTS caused a similar effect as them on airway remodeling. Additionally, CTS also played a similar role as the TGF-β1 inhibitor or TGF-β1 siRNA in TGF-β1/STAT3 signaling pathways in airway remodeling. The anti-inflammatory effects of CTS against OVA-induced airway remodeling may be through inhibiting STAT3, which further suppresses TWEAK and TGF-β1 signaling cross talk in asthma. CTS may be a promising therapeutic reagent for asthma treatment.

LncRNA Snhg3 contributes to dysfunction of cerebral microvascular cells in intracerebral hemorrhage rats by activating the TWEAK/Fn14/STAT3 pathway

LncRNA small nucleolar RNA host gene 3 (Snhg3) has been involved in cell proliferation and migration in malignant cells. However, its role in regulating functions of non-malignant cells has been hardly reported. Here, we found Snhg3 expression was sharply induced in primary brain microvascular endothelial cells (BMVECs) treated with oxygen-and-glucose-deprivation (OGD) plus hemin, an in vitro model of intracerebral hemorrhage (ICH). Downregulation of Snhg3 by siRNA transfection improved cell proliferation and migration abilities and reduced cell apoptosis and monolayer permeability in BMVECs under treatment with OGD plus hemin. Snhg3 overexpression suppressed cell proliferation and migration and increased cell apoptosis and monolayer permeability under normal condition. In ICH rats, downregulation of Snhg3 by siRNA injection improved behavioral and histological manifestations, including number of right turns, limb placement score, integrity of blood-brain barrier (BBB), brain water content and cell apoptosis in vivo. In the mechanism exploration, we found that, TWEAK and Snhg3 displayed a positive correlation with each other. Snhg3 overexpression increased expression of TWEAK protein and its receptor Fn14, that were also induced by OGD plus hemin, activating the downstream neuroinflammatory pathway STAT3 and enhancing the secretion of MMP-2/9. Finally, the TWEAK-siRNA, the Fn14 inhibitor ATA and the STAT3 blocker AG490 were respectively used to treat BMVECs under treatment with OGD plus hemin. Our results showed either TWEAK downregulation, Fn14 inhibition, or STAT3 blockade, could rescue Snhg3-induced impairment of BMVEC functions. In conclusion, the lncRNA Snhg3 contributes to dysfunction of cerebral microvascular cells in ICH rats by activating the TWEAK/Fn14/STAT3 pathway.

Ginkgo Flavonol Glycosides or Ginkgolides Tend to Differentially Protect Myocardial or Cerebral Ischemia-Reperfusion Injury via Regulation of TWEAK-Fn14 Signaling in Heart and Brain

Shuxuening injection (SXNI), one of the pharmaceutical preparations of Ginkgo biloba extract, has significant effects on both ischemic stroke and heart diseases from bench to bedside. Its major active ingredients are ginkgo flavonol glycosides (GFGs) and ginkgolides (GGs). We have previously reported that SXNI as a whole protected ischemic brain and heart, but the active ingredients and their contribution to the therapeutic effects remain unclear. Therefore, we combined experimental and network analysis approach to further explore the specific effects and underlying mechanisms of GFGs and GGs of SXNI on ischemia–reperfusion injury in mouse brain and heart. In the myocardial ischemia–reperfusion injury (MIRI) model, pretreatment with GFGs at 2.5 ml/kg was superior to the same dose of GGs in improving cardiac function and coronary blood flow and reducing the levels of lactate dehydrogenase and aspartate aminotransferase in serum, with an effect similar to that achieved by SXNI. In contrast, pretreatment with GGs at 2.5 ml/kg reduced cerebral infarction area and cerebral edema similarly to that of SXNI but more significantly compared with GFGs in cerebral ischemia–reperfusion injury (CIRI) model. Network pharmacology analysis of GFGs and GGs revealed that tumor necrosis factor-related weak inducer of apoptosis (TWEAK)–fibroblast growth factor-inducible 14 (Fn14) signaling pathway as an important common mechanism but with differential targets in MIRI and CIRI. In addition, immunohistochemistry and enzyme linked immunosorbent assay (ELISA) assays were performed to evaluate the regulatory roles of GFGs and GGs on the common TWEAK–Fn14 signaling pathway to protect the heart and brain. Experimental results confirmed that TWEAK ligand and Fn14 receptor were downregulated by GFGs to mitigate MIRI in the heart while upregulated by GGs to improve CIRI in the brain. In conclusion, our study showed that GFGs and GGs of SXNI tend to differentially protect brain and heart from ischemia–reperfusion injuries at least in part by regulating a common TWEAK–Fn14 signaling pathway.

Novel Drug Targets for Ischemic Stroke Identified Through Mendelian Randomization Analysis of the Blood Proteome

BACKGROUND

Novel, effective, and safe drugs are warranted for treatment of ischemic stroke. Circulating protein biomarkers with causal genetic evidence represent promising drug targets, but no systematic screen of the proteome has been performed.

METHODS

First, using Mendelian randomization (MR) analyses, we assessed 653 circulating proteins as possible causal mediators for 3 different subtypes of ischemic stroke: large artery atherosclerosis, cardioembolic stroke, and small artery occlusion. Second, we used MR to assess whether identified biomarkers also affect risk for intracranial bleeding, specifically intracerebral and subarachnoid hemorrhages. Third, we expanded this analysis to 679 diseases to test a broad spectrum of side effects associated with hypothetical therapeutic agents for ischemic stroke that target the identified biomarkers. For all MR analyses, summary-level data from genome-wide association studies (GWAS) were used to ascertain genetic effects on circulating biomarker levels versus disease risk. Biomarker effects were derived by meta-analysis of 5 GWAS (N≤20 509). Disease effects were derived from large GWAS analyses, including MEGASTROKE (N≤322 150) and UK Biobank (N≤408 961) studies.

RESULTS

Several biomarkers emerged as causal mediators for ischemic stroke. Causal mediators for cardioembolic stroke included histo-blood group ABO system transferase, coagulation factor XI, scavenger receptor class A5 (SCARA5), and tumor necrosis factor-like weak inducer of apoptosis (TNFSF12). Causal mediators for large artery atherosclerosis included ABO, cluster of differentiation 40, apolipoprotein(a), and matrix metalloproteinase-12. SCARA5 (odds ratio [OR]=0.78; 95% CI, 0.70-0.88; P=1.46×10^-5) and TNFSF12 (OR=0.86; 95% CI, 0.81-0.91; P=7.69×10^-7) represent novel protective mediators of cardioembolic stroke. TNFSF12 also increased the risk of subarachnoid (OR=1.53; 95% CI, 1.31-1.78; P=3.32×10^-8) and intracerebral (OR=1.34; 95% CI, 1.14-1.58; P=4.05×10^-4) hemorrhages, whereas SCARA5 decreased the risk of subarachnoid hemorrhage (OR=0.61; 95% CI, 0.47-0.81; P=5.20×10^-4). Multiple side effects beyond stroke were identified for 6 of 7 biomarkers, most (75%) of which were beneficial. No adverse side effects were found for coagulation factor XI, apolipoprotein(a), and SCARA5.

CONCLUSIONS

Through a systematic MR screen of the circulating proteome, causal roles for 5 established and 2 novel biomarkers for ischemic stroke were identified. Side-effect profiles were characterized to help inform drug target prioritization. In particular, SCARA5 represents a promising target for treatment of cardioembolic stroke, with no predicted adverse side effects.

TWEAK/Fn14 mediates atrial-derived HL-1 myocytes hypertrophy via JAK2/STAT3 signalling pathway

Atrial myocyte hypertrophy is one of the most important substrates in the development of atrial fibrillation (AF). The TWEAK/Fn14 axis is a positive regulator of cardiac hypertrophy in cardiomyopathy. This study therefore investigated the effects of Fn14 on atrial hypertrophy and underlying cellular mechanisms using HL‐1 atrial myocytes. In patients with AF, Fn14 protein levels were higher in atrial myocytes from atrial appendages, and expression of TWEAK was increased in peripheral blood mononuclear cells, while TWEAK serum levels were decreased. In vitro, Fn14 expression was up‐regulated in response to TWEAK treatment in HL‐1 atrial myocytes. TWEAK increased the expression of ANP and Troponin T, and Fn14 knockdown counteracted the effect. Inhibition of JAK2, STAT3 by specific siRNA attenuated TWEAK‐induced HL‐1 atrial myocytes hypertrophy. In conclusion, TWEAK/Fn14 axis mediates HL‐1 atrial myocytes hypertrophy partly through activation of the JAK2/STAT3 pathway.