In cardiac fibroblasts, interferon-beta attenuates differentiation, collagen synthesis, and TGF-β1-induced collagen gel contraction

GRK2-facilitated TLR4 signaling promotes cardiac fibrosis in rheumatic mice

OBJECTIVE

Patients with rheumatoid arthritis (RA) have a much higher prevalence of cardiac dysfunction, which explains the high mortality rate in RA patients despite treatment with anti-arthritic drugs. This study elucidates a molecular mechanism that causes abnormal activation of cardiac fibroblasts in the inflammatory state of RA through transactivation of canonical TLR4 signaling by GRK2-dependent signaling mechanisms, and which ultimately induces heart disease.

METHODS AND RESULTS

Collagen-induced arthritis (CIA) models were established in mice, and the cardiac function in these CIA mice was dynamically examined using echocardiography. Cardiac diastolic and systolic dysfunction appeared and persisted in the hearts of CIA mice even after joint inflammation subsides, and significant fibrosis occurred in the cardiac tissue. TLR4 expression was elevated in the hearts of CIA mice which was associated with cardiac fibrosis. Cardiac fibroblasts from CIA mice undergo aberrant proliferation and a significant increase in NF-κB p65 nuclear translocation. Treatment with the specific TLR4 inhibitor, TAK-242, effectively protected CIA mice from cardiac fibrosis and cardiac diastolic dysfunction. Cardiac function was effectively rescued by administration of the GRK2 inhibitor paroxetine and carvedilol as well, with a concomitant reduction in NF-κB nuclear localization. In cardiac tissues of CIA mice, elevated levels of GRK2 expression thereby cause cardiac fibroblasts to undergo transdifferentiation.

CONCLUSION

GRK2 transactivates TLR4 signaling, which promoted cardiac fibroblast transdifferentiation. Furthermore, GRK2 inhibition effectively mitigated myocardial fibrosis and protected cardiac function, which offered an important strategy to protect RA patients from heart failure.

Discovering new hub genes of dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) has a poor prognosis and exhibits a complex and diverse aetiology and genetic profile. The genes responsible for the pathogenesis of DCM have not been fully identified. The present study aimed to explore new hub genes of DCM by mining the human DCM databases and further by experimental validation.

METHODS

Two gene expression profiles of human DCM (GSE9800 and GSE120895) in the Gene Expression Omnibus (GEO) database were analysed to identify the differentially expressed genes (DEGs) (DCM vs. normal) and to obtain the common DEGs (cDEGs, between GSE9800 and GSE120895) using bioinformatic methods. The cDEGs were subjected to Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and the protein-protein interaction (PPI) networks and functional modules were constructed to screen the hub genes. The screened hub genes were identified using the Online Mendelian Inheritance in Man (OMIM) dataset, and their transcription and translation levels were further verified by real-time quantitative PCR (RT-qPCR) and western blotting using doxorubicin (DOX)-treated H9C2 cardiomyocytes that simulate the cellular pathology of DCM, with phosphate-buffered saline (PBS)-treated H9C2 cells as a normal control.

RESULTS

A total of 47 cDEGs were screened out, and 19 DCM-associated hub genes were identified. Among the 19 hub genes, 6 genes (NFKBIB, PSMC4, PSMD3, RAD21, PRNP and STAT2) have not yet been reported as associated with DCM. Among the six genes, NFKBIB and PRNP showed up-regulations, whereas PSMC4, PSMD3 and RAD21 exhibited down-regulations in their mRNA and protein expression levels in DOX-treated H9C2 cardiomyocytes compared with the control H9C2 cells (all P < 0.05). The remaining STAT2 showed a significant up-regulation in its protein expression (P < 0.05), while its mRNA up-regulation did not reach a statistical significance (P = 0.1082).

CONCLUSIONS

Six new hub genes of DCM (NFKBIB, PSMC4, PSMD3, RAD21, PRNP and STAT2) were identified by bioinformatic analysis and experimental validation in this study. These hub genes or their products may potentially be new diagnostic biomarkers or therapeutic targets for DCM.

Modelling myocardial ischemia/reperfusion injury with inflammatory response in human ventricular cardiac organoids

Current therapeutic drug exploring targeting at myocardial ischemia/reperfusion (I/R) injury is limited due to the lack of humanized cardiac models that resemble myocardial damage and inflammatory response. Herein, we develop ventricular cardiac organoids from human induced pluripotent stem cells (hiPSCs) and simulate I/R injury by hypoxia/reoxygenation (H/R), which results in increased cardiomyocytes apoptosis, elevated oxidative stress, disrupted morphological structure and decreased beat amplitude. RNA-seq reveals a potential role of type I interferon (IFN-I) in this I/R injury model. We then introduce THP-1 cells and reveal inflammatory responses between monocytes/macrophages and H/R-induced ventricular cardiac organoids. Furthermore, we demonstrate Anifrolumab, an FDA approved antagonist of IFN-I receptor, effectively decreases IFN-I secretion and related gene expression, attenuates H/R-induced inflammation and oxidative stress in the co-culture system. This study advances the modelling of myocardial I/R injury with inflammatory response in human cardiac organoids, which provides a reliable platform for preclinical study and drug screening.

Quercetin Alleviates Cardiac Fibrosis via Regulating the SIRT3 Signaling Pathway

PURPOSE

Cardiovascular diseases, exacerbated by cardiac fibrosis, are the leading causes of mortality. We aimed to determine the role of quercetin (QU) in cardiac fibrosis and the underlying mechanism.

METHODS

In this study, 8-week-old mice were subjected to either transverse aortic constriction (TAC) or sham surgery, then they were administered QU or saline. Thereafter, cardiac function and cardiac hypertrophy were accessed. In vitro, cardiac fibroblasts (CFs) were treated with angiotensin II (Ang II) with or without QU. Western blot, qPCR, EdU incorporation assay, and immunofluorescence staining analysis were used to investigate the molecular and cellular features.

RESULTS

For the TAC mouse model, cardiac fibrosis was alleviated by QU. The study revealed that the trans-differentiation and proliferation of CFs promoted by Ang II would be reversed by QU in vitro. Mechanistically, QU exerted the anti-fibrotic effect by regulating the SIRT3/TGF-β/Smad3 signaling pathway.

CONCLUSION

Quercetin protects against cardiac fibrosis by mediating the SIRT3 signaling pathway.

Spatially clustered type I interferon responses at injury borderzones

Sterile inflammation after myocardial infarction is classically credited to myeloid cells interacting with dead cell debris in the infarct zone1,2. Here we show that cardiomyocytes are the dominant initiators of a previously undescribed type I interferon response in the infarct borderzone. Using spatial transcriptomics analysis in mice and humans, we find that myocardial infarction induces colonies of interferon-induced cells (IFNICs) expressing interferon-stimulated genes decorating the borderzone, where cardiomyocytes experience mechanical stress, nuclear rupture and escape of chromosomal DNA. Cardiomyocyte-selective deletion of Irf3 abrogated IFNIC colonies, whereas mice lacking Irf3 in fibroblasts, macrophages, neutrophils or endothelial cells, Ccr2-deficient mice or plasmacytoid-dendritic-cell-depleted mice did not. Interferons blunted the protective matricellular programs and contractile function of borderzone fibroblasts, and increased vulnerability to pathological remodelling. In mice that died after myocardial infarction, IFNIC colonies were immediately adjacent to sites of ventricular rupture, while mice lacking IFNICs were protected from rupture and exhibited improved survival3. Together, these results reveal a pathological borderzone niche characterized by a cardiomyocyte-initiated innate immune response. We suggest that selective inhibition of IRF3 activation in non-immune cells could limit ischaemic cardiomyopathy while avoiding broad immunosuppression.

Linoleyl acetate and mandenol alleviate HUA-induced ED via NLRP3 inflammasome and JAK2/STAT3 signalling conduction in rats

Hyperuricemia (HUA) is characterized by elevated blood uric acid levels, which can increase the risk of erectile dysfunction (ED). Clinical studies have demonstrated satisfactory efficacy of a traditional Chinese medicine formula QYHT decoction in improving ED. Furthermore, the main monomeric components of this formula, linoleyl acetate and mandenol, demonstrate promise in the treatment of ED. This study established an ED rat model induced by HUA and the animals were administered with linoleyl acetate and mandenol. HE and TUNEL were performed to detect tissue changes, ELISA to measure the levels of serum testosterone (T), MDA, NO, CRP, and TNF-α and qPCR and WB to assess the expression levels of NLRP3, ASC, Caspase-1, JAK2, and STAT3 in whole blood. The findings showed that linoleyl acetate and mandenol improved kidney tissue morphology, reduced cell apoptosis in penile tissue, significantly increased T and NO levels, while substantially decreasing levels of MDA, CRP, and TNF-α. Meanwhile, the expression of NLRP3, ASC, and Caspase-1 mRNAs and proteins was markedly reduced, and the phosphorylation of JAK2 and STAT3 was inhibited. These findings were further validated through faecal microbiota transplantation results. Taken together, linoleyl acetate and mandenol could inhibit NLRP3 inflammasome activation, reduce inflammatory and oxidative stress responses, suppress the activity of JAK-STAT signalling pathway, ultimately providing a potential treatment for HUA-induced ED.

Adult cardiomyocytes-derived EVs for the treatment of cardiac fibrosis

Cardiac fibrosis is a common pathological feature of cardiovascular diseases that arises from the hyperactivation of fibroblasts and excessive extracellular matrix (ECM) deposition, leading to impaired cardiac function and potentially heart failure or arrhythmia. Extracellular vesicles (EVs) released by cardiomyocytes (CMs) regulate various physiological functions essential for myocardial homeostasis, which are disrupted in cardiac disease. Therefore, healthy CM-derived EVs represent a promising cell-free therapy for the treatment of cardiac fibrosis. To this end, we optimized the culture conditions of human adult CMs to obtain a large yield of EVs without compromising cellular integrity by using a defined combination of small molecules. EVs were isolated by ultracentrifugation, and their characteristics were analysed. Finally, their effect on fibrosis was tested. Treatment of TGFβ-activated human cardiac fibroblasts with EVs derived from CMs using our culture system resulted in a decrease in fibroblast activation markers and ECM accumulation. The rescued phenotype was associated with specific EV cargo, including multiple myocyte-specific and antifibrotic microRNAs, although their effect individually was not as effective as the EV treatment. Notably, pathway analysis showed that EV treatment reverted the transcription of activated fibroblasts and decreased several signalling pathways, including MAPK, mTOR, JAK/STAT, TGFβ, and PI3K/Akt, all of which are involved in fibrosis development. Intracardiac injection of CM-derived EVs in an animal model of cardiac fibrosis reduced fibrotic area and increased angiogenesis, which correlated with improved cardiac function. These findings suggest that EVs derived from human adult CMs may offer a targeted and effective treatment for cardiac fibrosis, owing to their antifibrotic properties and the specificity of cargo.

Angiotensin II Is Involved in MLKL Activation During the Development of Heart Failure Following Myocardial Infarction in Rats

Several reports assume that myocardial necroptotic cell death is induced during the development of chronic heart failure. Although it is well accepted that angiotensin II induces apoptotic cell death of cardiac myocytes, the involvement of angiotensin II in the induction of myocardial necroptosis during the development of heart failure is still unknown. Therefore, we examined the role of angiotensin II in myocardial necroptosis using rat failing hearts following myocardial infarction and cultured cardiomyocytes. We found that administration of azilsartan, an angiotensin II AT1 receptor blocker, or trandolapril, an angiotensin-converting enzyme inhibitor, to rats from the 2nd to the 8th week after myocardial infarction resulted in preservation of cardiac function and attenuation of mixed lineage kinase domain-like (MLKL) activation. Furthermore, the ratio of necroptotic cell death was increased in neonatal rat ventricular cardiomyocytes cultured with conditioned medium from rat cardiac fibroblasts in the presence of angiotensin II. This increase in necroptotic cells was attenuated by pretreatment with azilsartan. Furthermore, activated MLKL was increased in cardiomyocytes cultured in conditioned medium. Pretreatment with azilsartan also prevented the conditioned medium-induced increase in activated MLKL. These results suggest that angiotensin II contributes to the induction of myocardial necroptosis during the development of heart failure.

Maintenance of chronicity signatures in fibroblasts isolated from recessive dystrophic epidermolysis bullosa chronic wound dressings under culture conditions

BACKGROUND

Recessive Dystrophic Epidermolysis Bullosa (RDEB) is a rare inherited skin disease caused by variants in the COL7A1 gene, coding for type VII collagen (C7), an important component of anchoring fibrils in the basement membrane of the epidermis. RDEB patients suffer from skin fragility starting with blister formation and evolving into chronic wounds, inflammation and skin fibrosis, with a high risk of developing aggressive skin carcinomas. Restricted therapeutic options are limited by the lack of in vitro models of defective wound healing in RDEB patients.

RESULTS

In order to explore a more efficient, non-invasive in vitro model for RDEB studies, we obtained patient fibroblasts derived from discarded dressings) and examined their phenotypic features compared with fibroblasts derived from non-injured skin of RDEB and healthy-donor skin biopsies. Our results demonstrate that fibroblasts derived from RDEB chronic wounds (RDEB-CW) displayed characteristics of senescent cells, increased myofibroblast differentiation, and augmented levels of TGF-β1 signaling components compared to fibroblasts derived from RDEB acute wounds and unaffected RDEB skin as well as skin from healthy-donors. Furthermore, RDEB-CW fibroblasts exhibited an increased pattern of inflammatory cytokine secretion (IL-1β and IL-6) when compared with RDEB and control fibroblasts. Interestingly, these aberrant patterns were found specifically in RDEB-CW fibroblasts independent of the culturing method, since fibroblasts obtained from dressing of acute wounds displayed a phenotype more similar to fibroblasts obtained from RDEB normal skin biopsies.

CONCLUSIONS

Our results show that in vitro cultured RDEB-CW fibroblasts maintain distinctive cellular and molecular characteristics resembling the inflammatory and fibrotic microenvironment observed in RDEB patients' chronic wounds. This work describes a novel, non-invasive and painless strategy to obtain human fibroblasts chronically subjected to an inflammatory and fibrotic environment, supporting their use as an accessible model for in vitro studies of RDEB wound healing pathogenesis. As such, this approach is well suited to testing new therapeutic strategies under controlled laboratory conditions.

Reconstructing vascular networks promotes the repair of skeletal muscle following volumetric muscle loss by pre-vascularized tissue constructs

Current treatment for complex and large-scale volumetric muscle loss (VML) injuries remains a limited success and have substantial disadvantages, due to the irreversible loss of muscle mass, slow muscle regeneration, and rapid formation of non-functional fibrosis scars. These VML injuries are accompanied by denervation and the destruction of native vasculature which increases difficulties in the functional restoration of muscle. Here, reconstruction of the vascular network at the injury site was offered as a possible solution for improving the repair of muscle defects through the timely supply of nutrients and oxygen to surrounding cells. A hydrogel-based tissue construct containing various densities of the vascular network was successfully created in the subcutaneous space of mice by manipulating hydrogel properties, and then implanted into the VML injury site. One month after implantation, the mouse treated with the highly vascularized tissue had extensive muscle repair at the injury site and only spent a shorter time completing the inclined plane tests. These findings suggest that the reconstruction of the functional vascular network at the VML injury site accelerated muscle fiber repair through a timely supply of sufficient blood and avoided invasion by host fibroblasts.

Effects of RAGE Deletion on the Cardiac Transcriptome during Aging

Cardiac aging is characterized by increased cardiomyocyte hypertrophy, myocardial stiffness, and fibrosis, which enhance cardiovascular risk. The receptor for advanced glycation end-products (RAGE) is involved in several age-related diseases. RAGE knockout (Rage−/−) mice show an acceleration of cardiac dimension changes and interstitial fibrosis with aging. This study identifies the age-associated cardiac gene expression signature induced by RAGE deletion. We analyzed the left ventricle transcriptome of 2.5-(Young), 12-(Middle age, MA), and 21-(Old) months-old female Rage−/− and C57BL/6N (WT) mice. By comparing Young, MA, and Old Rage−/− versus age-matched WT mice, we identified 122, 192, and 12 differently expressed genes, respectively. Functional inference analysis showed that RAGE deletion is associated with: (i) down-regulation of genes involved in antigen processing and presentation of exogenous antigen, adaptive immune response, and cellular responses to interferon beta and gamma in Young animals; (ii) up-regulation of genes related to fatty acid oxidation, cardiac structure remodeling and cellular response to hypoxia in MA mice; (iii) up-regulation of few genes belonging to complement activation and triglyceride biosynthetic process in Old animals. Our findings show that the age-dependent cardiac phenotype of Rage−/− mice is associated with alterations of genes related to adaptive immunity and cardiac stress pathways.

Preparation, characterization and in vitro study of bellidifolin nano-micelles

Bellidifolin (BEL), a xanthone compound, has significant therapeutic effectiveness in cardiac diseases such as arrhythmias. However, BEL is limited in clinical applications by its hydrophobicity. In this work, we used BEL as the active pharmaceutical ingredient (API), and polyethylene glycol 15-hydroxy stearate (Kolliphor HS15) as the carrier to prepare BEL nano-micelles by a solvent-volatilization method. According to an analysis by differential scanning calorimetry (DSC), BEL was successfully encapsulated in HS15 as BEL nano-micelles with a 90% encapsulation rate, and particle size was 12.60 ± 0.074 nm in the shape of a sphere and electric potential was −4.76 ± 4.47 mV with good stability and sustained release characteristics. In addition, compared with free drugs, these nano-micelles can increase cellular uptake capacity, inhibit the proliferation of human cardiac fibroblasts, and down-regulate the expression of Smad-2, α-SMA, Collagen I, and Collagen III proteins in myocardial cells to improve myocardial fibrosis. In conclusion, the BEL nano-micelles can provide a new way for the theoretical basis for the clinical application of anti-cardiac fibrosis.

Bellidifolin (BEL), a xanthone compound, has significant therapeutic effectiveness in cardiac diseases such as arrhythmias.

The molecular mechanisms underlying arecoline-induced cardiac fibrosis in rats

The areca nut is one of the most commonly consumed psychoactive substances worldwide, with an estimated consumption by approximately 10% of the world’s population, especially in some regions of South Asia, East Africa, and the tropical Pacific. Arecoline, the major areca nut alkaloid, has been classified as carcinogenic to humans as it adversely affects various organs, including the brain, heart, lungs, gastrointestinal tract, and reproductive organs. Earlier studies have established a link between areca nut chewing and cardiac arrhythmias, and yet research pertaining to the mechanisms underlying cardiotoxicity caused by arecoline is still preliminary. The main purpose of this study is to test the hypothesis that arecoline causes cardiac fibrosis through transforming growth factor-β (TGF-β)/Smad-mediated signaling pathways. Male Wistar rats were injected intraperitoneally with low (5 mg/kg/day) or high (50 mg/kg/day) doses of arecoline for 3 weeks. Results from Masson’s trichrome staining indicated that arecoline could induce cardiac fibrosis through collagen accumulation. Western blot analysis showed that TGF-β and p-Smad2/3 protein expression levels were markedly higher in the arecoline-injected rat hearts than in those of the control rats. Moreover, arecoline upregulated other fibrotic-related proteins, including SP1-mediated connective tissue growth factor expression. Tissue-type plasminogen activator and its inhibitor, plasminogen activator inhibitor, and matrix metalloproteinase (MMP) 9 were upregulated, and the inhibitor of MMP9 was downregulated. This study provides novel insight into the molecular mechanisms underlying arecoline-induced cardiac fibrosis. Taken together, the areca nut is a harmful substance, and the detrimental effects of arecoline on the heart are similar to that caused by oral submucous fibrosis.

COVID-19-related cardiac complications from clinical evidences to basic mechanisms: opinion paper of the ESC Working Group on Cellular Biology of the Heart

The pandemic of coronavirus disease (COVID)-19 is a global threat, causing high mortality, especially in the elderly. The main symptoms and the primary cause of death are related to interstitial pneumonia. Viral entry also into myocardial cells mainly via the angiotensin converting enzyme type 2 (ACE2) receptor and excessive production of pro-inflammatory cytokines, however, also make the heart susceptible to injury. In addition to the immediate damage caused by the acute inflammatory response, the heart may also suffer from long-term consequences of COVID-19, potentially causing a post-pandemic increase in cardiac complications. Although the main cause of cardiac damage in COVID-19 remains coagulopathy with micro- (and to a lesser extent macro-) vascular occlusion, open questions remain about other possible modalities of cardiac dysfunction, such as direct infection of myocardial cells, effects of cytokines storm, and mechanisms related to enhanced coagulopathy. In this opinion paper, we focus on these lesser appreciated possibilities and propose experimental approaches that could provide a more comprehensive understanding of the cellular and molecular bases of cardiac injury in COVID-19 patients. We first discuss approaches to characterize cardiac damage caused by possible direct viral infection of cardiac cells, followed by formulating hypotheses on how to reproduce and investigate the hyperinflammatory and pro-thrombotic conditions observed in the heart of COVID-19 patients using experimental in vitro systems. Finally, we elaborate on strategies to discover novel pathology biomarkers using omics platforms.