Interleukin-17A mediates cardiomyocyte apoptosis through Stat3-iNOS pathway

Screening of Secretory Proteins Linking Major Depressive Disorder with Heart Failure Based on Comprehensive Bioinformatics Analysis and Machine Learning

BACKGROUND

Major depressive disorder (MDD) plays a crucial role in the occurrence of heart failure (HF). This investigation was undertaken to explore the possible mechanism of MDD's involvement in HF pathogenesis and identify candidate biomarkers for the diagnosis of MDD with HF.

METHODS

GWAS data for MDD and HF were collected, and Mendelian randomization (MR) analysis was performed to investigate the causal relationship between MDD and HF. Differential expression analysis (DEA) and WGCNA were used to detect HF key genes and MDD-associated secretory proteins. Protein-protein interaction (PPI), functional enrichment, and cMAP analysis were used to reveal potential mechanisms and drugs for MDD-related HF. Then, four machine learning (ML) algorithms (including GLM, RF, SVM, and XGB) were used to screen candidate biomarkers, construct diagnostic nomograms, and predict MDD-related HF. Furthermore, the MCPcounter algorithm was used to explore immune cell infiltration in HF, and MR analysis was performed to explore the causal effect of immunophenotypes on HF. Finally, the validation of the association of MDD with reduced left ventricular ejection fraction (LVEF) and the performance assessment of diagnostic biomarkers was accomplished based on animal models mimicking MDD.

RESULTS

The MR analysis showed that the MDD was linked to an increased risk of HF (OR = 1.129, p < 0.001). DEA combined with WGCNA and secretory protein gene set identified 315 HF key genes and 332 MDD-associated secretory proteins, respectively. Through PPI and MCODE analysis, 78 genes were pinpointed as MDD-related pathogenic genes for HF. The enrichment analysis revealed that these genes were predominantly enriched in immune and inflammatory regulation. Through four ML algorithms, two hub genes (ISLR/SFRP4) were identified as candidate HF biomarkers, and a nomogram was developed. ROC analysis showed that the AUC of the nomogram was higher than 0.90 in both the HF combined dataset and two external cohorts. In addition, an immune cell infiltration analysis revealed the immune dysregulation in HF, with ISLR/SFRP4 displaying notable associations with the infiltration of B cells, CD8 T cells, and fibroblasts. More importantly, animal experiments showed that the expression levels of ISLR (r = -0.653, p < 0.001) and SFRP4 (r = -0.476, p = 0.008) were significantly negatively correlated with LVEF.

CONCLUSIONS

The MR analysis indicated that MDD is a risk factor for HF at the genetic level. Bioinformatics analysis and the ML results suggest that ISLR and SFRP4 have the potential to serve as diagnostic biomarkers for HF. Animal experiments showed a negative correlation between the serum levels of ISLR/SFRP4 and LVEF, emphasizing the need for additional clinical studies to elucidate their diagnostic value.

Oxidized high-density lipoprotein associates with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common heart arrhythmia and considered to be a progressive chronic disease associated with increased morbidity and mortality. Recent data suggest a link between inflammation, oxidative stress, and AF, although the underlying mechanisms are not fully understood. Because oxidized lipoproteins cause structural damage and electrophysiologic changes in cardiomyocytes, it is feasible that the transformation of atheroprotective high-density lipoprotein (HDL) into dysfunctional HDL contributes to the development of AF.

OBJECTIVE

The purpose of this study was to determine whether a reduced antioxidant function of HDL is associated with the presence of AF.

METHODS

In this multicenter cross-sectional cohort study, we assessed HDL function in sera of 1206 participants. Patients were divided into groups according to the presence of AF (n = 233) or no AF (n = 973). A validated cell-free biochemical assay was used to determine reduced HDL antioxidant function as assessed by increased normalized HDL lipid peroxide content (nHDLox).

RESULTS

Participants with AF had a 9% higher mean relative nHDLox compared to persons without AF (P = .025). nHDLox was strongly associated with AF in all models of logistic regression, including the analysis adjusted for age, sex, and risk factors for AF (all P ≤.01).

CONCLUSION

Reduced antioxidant HDL function is associated with the presence of AF, which supports growing evidence that impaired lipoprotein function is linked to electrophysiological changes in cardiomyocytes. nHDLox is one of several contributors to the initiation and perpetuation of AF.

Protective effect and mechanism of procyanidin B2 against hypoxic injury of cardiomyocytes

Background

Cardiomyocyte ischemia and hypoxia are important causes of oxidative stress damage and cardiomyocyte apoptosis in coronary heart disease (CHD). Epidemiological investigation has shown that eating more plant-based foods, such as vegetables and fruits, may significantly decrease the risk of CHD. As natural antioxidants, botanicals have fewer toxic side effects than chemical drugs and have great potential for development. Procyanidin B2 (PB2) is composed of flavan-3-ol and epicatechin and has been reported to have antioxidant and anti-inflammatory effects. However, whether PB2 exerts protective effects on hypoxic cardiomyocytes has remained unclear. This study aimed to explore the protective effect of PB2 against cardiomyocyte hypoxia and to provide new treatment strategies and ideas for myocardial ischemia and hypoxia in CHD.

Methods and results

A hypoxic cardiomyocyte model was constructed, and a CCK-8 assay proved that PB2 had a protective effect on cardiomyocytes in a hypoxic environment. DCFH fluorescence staining, DHE staining, and BODIPY lipid oxidation assessment revealed that PB2 reduced the oxidative stress levels of cardiomyocytes under hypoxic conditions. TUNEL staining, Annexin V/PI fluorescence flow cytometry, and Western blot analysis of the expression of the apoptosis marker protein cleaved caspase-3 confirmed that PB2 reduced cardiomyocyte apoptosis under hypoxic conditions. JC-1 staining indicated that PB2 reduced the mitochondrial membrane potential of cardiomyocytes under hypoxia. In addition, transcriptomic analysis proved that the expression of 158 genes in cardiomyocytes was significantly changed after PB2 was added during hypoxia, of which 53 genes were upregulated and 105 genes were downregulated. GO enrichment analysis demonstrated that the activity of cytokines, extracellular matrix proteins and other molecules was changed significantly in the biological process category. KEGG enrichment analysis showed that the IL-17 signaling pathway and JAK-STAT signaling pathway underwent significant changes. We also performed metabolomic analysis and found that the levels of 51 metabolites were significantly changed after the addition of PB2 to cardiomyocytes during hypoxia. Among them, 39 metabolites exhibited increased levels, while 12 metabolites exhibited decreased levels. KEGG enrichment analysis showed that cysteine and methionine metabolism, arginine and proline metabolism and other metabolic pathways underwent remarkable changes.

Conclusion

This study proves that PB2 can reduce the oxidative stress and apoptosis of cardiomyocytes during hypoxia to play a protective role. Transcriptomic and metabolomic analyses preliminarily revealed signaling pathways and metabolic pathways that are related to its protective mechanism. These findings lay a foundation for further research on the role of PB2 in the treatment of CHD and provide new ideas and new perspectives for research on PB2 in the treatment of other diseases.

Pathophysiological Effects of Various Interleukins on Primary Cell Types in Common Heart Disease

Myocardial infarction (MI), heart failure, cardiomyopathy, myocarditis, and myocardial ischemia-reperfusion injury (I/R) are the most common heart diseases, yet there is currently no effective therapy due to their complex pathogenesis. Cardiomyocytes (CMs), fibroblasts (FBs), endothelial cells (ECs), and immune cells are the primary cell types involved in heart disorders, and, thus, targeting a specific cell type for the treatment of heart disease may be more effective. The same interleukin may have various effects on different kinds of cell types in heart disease, yet the exact role of interleukins and their pathophysiological pathways on primary cell types remain largely unexplored. This review will focus on the pathophysiological effects of various interleukins including the IL-1 family (IL-1, IL-18, IL-33, IL-37), IL-2, IL-4, the IL-6 family (IL-6 and IL-11), IL-8, IL-10, IL-17 on primary cell types in common heart disease, which may contribute to the more precise and effective treatment of heart disease.

More than a key-the pathological roles of SARS-CoV-2 spike protein in COVID-19 related cardiac injury

Cardiac injury is common in hospitalized coronavirus disease 2019 (COVID-19) patients and cardiac abnormalities have been observed in a significant number of recovered COVID-19 patients, portending long-term health issues for millions of infected individuals. To better understand how Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, CoV-2 for short) damages the heart, it is critical to fully comprehend the biology of CoV-2 encoded proteins, each of which may play multiple pathological roles. For example, CoV-2 spike glycoprotein (CoV-2-S) not only engages angiotensin converting enzyme II (ACE2) to mediate virus infection but also directly activates immune responses. In this work, the goal is to review the known pathological roles of CoV-2-S in the cardiovascular system, thereby shedding lights on the pathogenesis of COVID-19 related cardiac injury.

Protective effect of Secukinumab on severe sepsis model rats by neutralizing IL-17A to inhibit IKBα/NFκB inflammatory signal pathway

Secukinumab is a specific neutralizing antibody for IL-17A. At present, numerous studies have confirmed the important role of IL-17A in sepsis, but the role of secukinumab in sepsis has not been studied. The present study explored the protective effect and underlying mechanism of secukinumab in severe sepsis model rats. We established a severe sepsis rat model using cecal ligation and puncture (CLP). The optimal dose of secukinumab was determined by observing the 7-day survival rate of severe sepsis model rats. The expression levels of TNF-α, IL-6, and IL-17A in plasma and lung tissue were determined by enzyme-linked immunosorbent assay. The degree of pathological damage to lung tissue was evaluated by hematoxylin–eosin (H–E) staining and pathological damage scale. The expressions of IKBα/NFκB pathway proteins and downstream-related inflammatory factors were detected by western blotting and real-time quantitative polymerase chain reaction (RT-qPCR). Our results show that high-dose secukinumab can inhibit the activation of the IKBα/NFκB inflammatory pathway by neutralizing IL-17A and reducing the gene expression of pathway-related inflammatory cytokines, thereby reducing the levels of inflammatory cytokines in lung tissue and plasma, thereby reducing the damage of lung tissue in severe sepsis model rats and improving the systemic inflammatory response.

Cardiomyocyte IL-1R2 protects heart from ischemia/reperfusion injury by attenuating IL-17RA-mediated cardiomyocyte apoptosis

Myocardial ischemia reperfusion (I/R) injury is a complex process with intense inflammatory response and cardiomyocyte apoptosis. As a decoy receptor of IL-1β, Interleukin-1 receptor type 2 (IL-1R2) inhibits IL-1β signaling. However, its role in I/R injury remains unknown. Here we found that the serum levels of IL-1R2 were significantly increased in patients with acute myocardial infarction (AMI) following interventional therapy. Similarly, after myocardial I/R surgery, IL-1R2 expression was significantly increased in heart of wild-type mice. In addition, IL-1R2-deficient mice heart showed enlarged infarct size, increased cardiomyocyte apoptosis together with reduced cardiac systolic function. Following exposure to hypoxia and reoxygenation (H/R), neonatal rat ventricular myocytes (NRVM) significantly increased IL-1R2 expression relying on NF-κB activation. Consistently, IL-1R2-deficient mice increased immune cells infiltrating into heart after surgery, which was relevant with cardiac damage. Additionally, IL-1R2 overexpression in cardiomyocyte protected cardiomyocyte against apoptosis through reducing the IL-17RA expression both in vivo and in vitro. Our results indicate that IL-1R2 protects cardiomyocytes from apoptosis, which provides a therapeutic approach to turn down myocardial I/R injury.

Renoprotection Induced by Aerobic Training Is Dependent on Nitric Oxide Bioavailability in Obese Zucker Rats

Aerobic training (AT) promotes several health benefits that may attenuate the progression of obesity associated diabetes. Since AT is an important nitric oxide (NO⁻) inducer mediating kidney-healthy phenotype, the present study is aimed at investigating the effects of AT on metabolic parameters, morphological, redox balance, inflammatory profile, and vasoactive peptides in the kidney of obese-diabetic Zucker rats receiving L-NAME (N(omega)-nitro-L-arginine methyl ester). Forty male Zucker rats (6 wk old) were assigned into four groups (n = 10, each): sedentary lean rats (CTL-Lean), sedentary obese rats (CTL-Obese), AT trained obese rats without blocking nitric oxide synthase (NOS) (Obese+AT), and obese-trained with NOS block (Obese+AT+L-NAME). AT groups ran 60 min in the maximal lactate steady state (MLSS), five days/wk/8 wk. Obese+AT rats improved glycemic homeostasis, SBP, aerobic capacity, renal mitochondria integrity, redox balance, inflammatory profile (e.g., TNF-α, CRP, IL-10, IL-4, and IL-17a), and molecules related to renal NO⁻ metabolism (klotho/FGF23 axis, vasoactive peptides, renal histology, and reduced proteinuria). However, none of these positive outcomes were observed in CTL-Obese and Obese+AT+L-NAME (p < 0.0001) groups. Although Obese+AT+L-NAME lowered BP (compared with CTL-Obese; p < 0.0001), renal damage was observed after AT intervention. Furthermore, AT training under conditions of low NO⁻ concentration increased signaling pathways associated with ACE-2/ANG1-7/MASr. We conclude that AT represents an important nonpharmacological intervention to improve kidney function in obese Zucker rats. However, these renal and metabolic benefits promoted by AT are dependent on NO⁻ bioavailability and its underlying regulatory mechanisms.

Emerging Biological Functions of IL-17A: A New Target in Chronic Obstructive Pulmonary Disease?

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease that causes high rates of disability and mortality worldwide because of severe progressive and irreversible symptoms. During the period of COPD initiation and progression, the immune system triggers the activation of various immune cells, including Regulatory T cells (Tregs), dendritic cells (DCs) and Th17 cells, and also the release of many different cytokines and chemokines, such as IL-17A and TGF-β. In recent years, studies have focused on the role of IL-17A in chronic inflammation process, which was found to play a highly critical role in facilitating COPD. Specially, IL-17A and its downstream regulators are potential therapeutic targets for COPD. We mainly focused on the possibility of IL-17A signaling pathways that involved in the progression of COPD; for instance, how IL-17A promotes airway remodeling in COPD? How IL-17A facilitates neutrophil inflammation in COPD? How IL-17A induces the expression of TSLP to promote the progression of COPD? Whether the mature DCs and Tregs participate in this process and how they cooperate with IL-17A to accelerate the development of COPD? And above associated studies could benefit clinical application of therapeutic targets of the disease. Moreover, four novel efficient therapies targeting IL-17A and other molecules for COPD are also concluded, such as Bufei Yishen formula (BYF), a Traditional Chinese Medicine (TCM), and curcumin, a natural polyphenol extracted from the root of Curcuma longa.

Interleukin-17 aggravates right ventricular remodeling via activating STAT3 under both normoxia and hypoxia

OBJECTIVE

Proinflammatory cytokine interleukin 17 (IL-17) is involved in ventricular remodeling, mainly of the left ventricle. This study was designed to explore the role of IL-17 played in the pathogenesis of right ventricular hypertrophy (RVH), aiming to provide a novel treatment target or diagnostic biomarker options for improving the care of RVH patients.

METHODS

C57BL/6 mice were maintained in 10% O2 chamber or room air for four weeks. Right ventricular hypertrophy index (RVHI), RV/body weight ratio, pulmonary arteriolar remodeling determined by percent media thickness (%MT), and the cardiomyocyte diameter of RV were evaluated. Mice were treated with exogenous recombinant mouse IL-17 (rmIL-17, 1 μg per dose twice a week) for four weeks. H9c2 cardiomyocytes were cultured and treated with IL-17 (10 ng/mL) and STAT3 inhibitor (10 ng/mL) either under normoxia (21% O2, 5% CO2, 74% N2) or under hypoxia (3% O2, 5% CO2, 92% N2). Cardiomyocyte viability was assessed by Cell counting kit 8 (CCK-8) assay. The mRNA level was detected by RT-PCR, where as the protein expression was measured by Western blot, immunohistochemistry, and immunofluorescent analyses.

RESULTS

In vivo experiments showed that IL-17 did not affect the pulmonary artery under normoxia, after treatment with rmIL-17, %MT was not changed, while RVHI and the RV/body weight ratio were increased, indicating that IL-17 directly induced right ventricular hypertrophy. In a time-course study, the mice were exposed to hypoxia for 0, 1, 2, 3, 4 weeks, respectively. We found that the expression of IL-17 was gradually upregulated in RV tissue in a time-dependent manner after one week of hypoxia exposure, especially at the third and fourth week. Cardiomyocyte hypertrophy and apoptosis were observed after the exposure of the mice to hypoxia for four weeks, rmIL-17 further aggravated the hypoxia-induced cardiomyocyte hypertrophy and apoptosis. The expression of p-STAT3 in the IL-17-deficient mice was lower than in the wild-type mice. In vitro, IL-17 inhibited cardiomyocyte viability and induced cardiomyocyte apoptosis via STAT3 under both normoxic and hypoxic conditions.

CONCLUSIONS

These findings support a role for IL-17 as a mediator in the pathogenesis RVH, which might be considered as a potential novel anti-inflammation therapeutic strategy or diagnostic biomarker for RVH.

miR-205/IRAK2 signaling pathway is associated with urban airborne PM2.5-induced myocardial toxicity

Exposure to fine particulate matter (PM_2.5) is closely linked with cardiovascular diseases. However, the underlying mechanism of PM_2.5 on cardiac function remains unknown. This study was aimed to investigate the role of microRNA-205 (miR-205) on PM_2.5-induced myocardial inflammation and cardiac dysfunction. PM_2.5 increased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), following by decreased cell viability and antioxidant enzymes, resulting in apoptosis of cardiomyocytes (AC16). The histopathological and ultrastructural analysis demonstrated that PM_2.5 caused myocardial damage via interstitial edema, inflammatory cell infiltration, and myocardial fiber destruction. PM_2.5 enhanced the release of inflammatory factors in AC16 cells and heart tissue. Microarray analysis and dual-luciferase reporter gene assays demonstrated that PM_2.5-induced down-regulation of miR-205 regulated interleukin 1 receptor-associated kinase 2 (IRAK2), which further activated the TNF receptor-associated factor 6 (TRAF6)/nuclear transcription factor-κB (NF-κB) signaling pathway in vivo. Moreover, the chemical mimics of miR-205 markedly inhibited the IRAK2/TRAF6/NF-κB signaling pathway, whereas the chemical inhibitors of miR-205 amplified PM_2.5-induced activation of the IRAK2 signaling pathway in vitro. In summary, our results found that PM_2.5 could trigger myocardial toxicity via miR-205 negative regulating the IRAK2/TRAF6/NF-κB signaling pathway. Our study suggests that miR-205 could be a promising target molecule for mitigating the hazardous effects of PM_2.5 on the cardiovascular system.

Biology of Interleukin-17 and Its Pathophysiological Significance in Sepsis

The interleukin (IL)-17 family includes six structure-related cytokines (A-F). To date, majority of studies have focused on IL-17A. IL-17A plays a pivotal role in various infectious diseases, inflammatory and autoimmune disorders, and cancer. Several recent studies have indicated that IL-17A is a biomarker as well as a therapeutic target in sepsis. In the current review, we summarize the biological functions of IL-17, including IL-17-mediated responses and signal transduction pathways, with particular emphasis on clinical relevance to sepsis.

Minocycline reverses IL-17A/TRAF3IP2-mediated p38 MAPK/NF-κB/iNOS/NO-dependent cardiomyocyte contractile depression and death

Minocycline, an FDA-approved second-generation semisynthetic tetracycline, exerts antioxidant, anti-apoptotic and anti-inflammatory effects, independent of its antimicrobial properties. Interleukin (IL)-17A is an immune and inflammatory mediator, and its sustained induction is associated with various cardiovascular diseases. Here we investigated (i) whether IL-17A induces cardiomyocyte contractile depression and death, (ii) whether minocycline reverses IL-17A's negative inotropic effects and (iii) investigated the underlying molecular mechanisms. Indeed, treatment with recombinant mouse IL-17A impaired adult cardiomyocyte contractility as evidenced by a 34% inhibition in maximal velocity of shortening and relengthening after 4 h (P < .01). Contractile depression followed iNOS induction at 2 h (2.13-fold, P < .01) and NO generation at 3 h (3.71-fold, P <.01). Further mechanistic investigations revealed that IL-17A-dependent induction of iNOS occurred via TRAF3IP2, TRAF6, TAK1, NF-κB, and p38MAPK signaling. 1400 W, a highly specific iNOS inhibitor, suppressed IL-17A-induced NO generation and contractile depression, where as the NO donors SNAP and PAPA-NONOate both suppressed cardiomyocyte contractility. IL-17A also stimulated cardiomyocyte IL-1β and TNF-α secretion, however, their neutralization failed to modulate IL-17A-mediated contractile depression or viability. Further increases of IL-17A concentration and the duration of exposure enhanced IL-1β and TNF-α secreted levels, buthad no impact on adult cardiomyocyte viability. However, when combined with pathophysiological concentrations of IL-1β or TNF-α, IL-17A promoted adult cardiomyocyte death. Importantly, minocycline blunted IL-17A-mediated deleterious effects, indicating its therapeutic potential in inflammatory cardiac diseases.

Nanomedicine for Gene Delivery for the Treatment of Cardiovascular Diseases

Background:

Myocardial infarction (MI) is the most severe ischemic heart disease and di-rectly leads to heart failure till death. Target molecules have been identified in the event of MI including increasing angiogenesis, promoting cardiomyocyte survival, improving heart function and restraining inflammation and myocyte activation and subsequent fibrosis. All of which are substantial in cardiomy-ocyte protection and preservation of cardiac function.

Methodology:

To modulate target molecule expression, virus and non-virus-mediated gene transfer have been investigated. Despite successful in animal models of MI, virus-mediated gene transfer is hampered by poor targeting efficiency, low packaging capacity for large DNA sequences, immunogenicity induced by virus and random integration into the human genome.

Discussion:

Nanoparticles could be synthesized and equipped on purpose for large-scale production. They are relatively small in size and do not incorporate into the genome. They could carry DNA and drug within the same transfer. All of these properties make them an alternative strategy for gene transfer. In the review, we first introduce the pathological progression of MI. After concise discussion on the current status of virus-mediated gene therapy in treating MI, we overview the history and development of nanoparticle-based gene delivery system. We point out the limitations and future perspective in the field of nanoparticle vehicle.

Conclusion:

Ultimately, we hope that this review could help to better understand how far we are with nanoparticle-facilitated gene transfer strategy and what obstacles we need to solve for utilization of na-nomedicine in the treatment of MI.

T-Cell Proapoptotic and Antifibrotic Activity Against Autologous Skin Fibroblasts in vitro Is Associated With IL-17A Axis Upregulation in Systemic Sclerosis

Background: Systemic sclerosis (SSc) T cells can induce apoptosis of autologous skin fibroblasts in vitro. Th17 cells have been reported to increase in SSc patients, and interleukin-17A (IL-17A) has a profibrotic function. We used a system based on T-cell-autologous fibroblast co-cultures to further investigate a possible role of IL-17A in SSc.

Methods: T cells from diffuse SSc patients were co-cultured with autologous skin fibroblasts. IL17A mRNA was assessed by real-time PCR in co-cultured and control T cells, while IL17RA, CXCL1, CCL2, CCL3, COL1A1, COL3A1, CTGF, TGFBR2, and SMAD3 mRNAs were assessed in co-cultured and control fibroblasts. In subset experiments, co-cultures and control cells were treated with either IL-17A or IL-17A plus anti-IL17 receptor monoclonal antibody (α-IL-17RA mAb). Chemokine and procollagen type I (PCI) production was further investigated at the protein level in cell culture supernatants by multiple suspension immunoassay and sandwich ELISA, respectively. Co-cultured and control fibroblasts were also stained with Annexin V and analyzed by flow cytometry.

Results: T cell–fibroblast co-cultures overexpressed IL17A and IL17RA. Furthermore, co-cultured fibroblasts upregulated IL-17A targets CXCL1, CCL2, and CCL3, while COL1A1, COL3A1, CTGF, and two key effectors of the TGF-β signaling, TGFBR2 and SMAD3, were found downregulated. Consistently, chemokine concentrations were increased in co-culture supernatants, while PCI levels were reduced, especially after stimulation with ectopic IL-17A. Finally, simultaneous α-IL-17RA mAb treatment restored PCI levels and reduced fibroblast apoptosis in IL-17A-stimulated co-cultures.

Conclusion: These data suggest that IL-17A upregulation might play a role in modulating T cell-mediated antifibrotic and proapoptotic effects in co-cultured autologous skin fibroblasts.

Cajanonic acid A regulates the ratio of Th17/Treg via inhibition of expression of IL-6 and TGF-β in insulin-resistant HepG2 cells

BACKGROUND

The objectives of the present study are to investigate whether cajanonic acid A (CAA) can reduce insulin resistance (IR) in HepG2 cells and to gain a preliminary understanding of the mechanisms underlying this effect.

METHODS

Following induction of IR in HepG2 cells, we tested the regulatory effect of CAA on glucose consumption and evaluated hepatocyte production of IL-6, TGF-β, and key molecules in the insulin transduction pathway. A transwell co-culturing system was used to assess the effect of CAA on IR in HepG2 cells during the differentiation of CD4+ T cells by calculating the ratio of (Th17)/regulatory T cell (Treg). We evaluated the effect of CAA on the expression of IL-17RC cells and HepG2 cell apoptosis by immunofluorescence and flow cytometry assay.

RESULTS

CAA improved dexamethasone-induced reduction in glucose consumption in HepG2 cells, inhibited hepatocyte production of IL-6 and TGF-β, increased the expression of IL-17RC cell, and increased cellular apoptosis in insulin-resistant HepG2 cells. When co-cultured with CD4+ T cells, insulin-resistant HepG2 cells induced a decrease in the ratio of Th17/Treg, but CAA dampened the effect. Application of IL-6 and TGF-β, together with CAA, reversed the effect of CAA on insulin-resistant HepG2 cells. Overexpression of IL17R, however, counteracted the effect of IL-6 neutralizing antibody within the culture system.

CONCLUSION

CAA can regulate the ratio of Th17/Treg by mediating the expression of IL-6 and TGF-β in insulin-resistant HepG2 cells.

CTRP9 induces iNOS expression through JAK2/STAT3 pathway in Raw 264.7 and peritoneal macrophages

The C1q tumor necrosis factor (TNF)-related proteins 9 (CTRP9), an adipocyte-derived cytokine, affects a number of physiological processes, including immune function and inflammation. We investigated whether CTRP9 affects the expression of inflammation-related genes in Raw 264.7 and peritoneal macrophages. The CTRP9-induced expression of iNOS increased in a time- and dose-dependent manner. LPS and CTRP9 promote the expression of iNOS jointly in Raw 264.7 and peritoneal macrophages. CTRP9 induced the phosphorylation of JAK2 and STAT3 in Raw 264.7 and peritoneal macrophages. VX509 (JAK2 inhibitor) reduced the CTRP9-induced iNOS protein production. In addition, the CTRP9-induced phosphorylation of JAK2 and STAT3 was dramatically reduced by VX509. Collectively, these results suggest that JAK2/STAT3 signaling is involved in the CTRP9-induced expression of iNOS.

A Dynamic Variation of Pulmonary ACE2 Is Required to Modulate Neutrophilic Inflammation in Response to Pseudomonas aeruginosa Lung Infection in Mice

Angiotensin-converting enzyme 2 (ACE2) is a potent negative regulator capable of restraining overactivation of the renin-angiotensin system, which contributes to exuberant inflammation after bacterial infection. However, the mechanism through which ACE2 modulates this inflammatory response is not well understood. Accumulating evidence indicates that infectious insults perturb ACE2 activity, allowing for uncontrolled inflammation. In the current study, we demonstrate that pulmonary ACE2 levels are dynamically varied during bacterial lung infection, and the fluctuation is critical in determining the severity of bacterial pneumonia. Specifically, we found that a pre-existing and persistent deficiency of active ACE2 led to excessive neutrophil accumulation in mouse lungs subjected to bacterial infection, resulting in a hyperinflammatory response and lung damage. In contrast, pre-existing and persistent increased ACE2 activity reduces neutrophil infiltration and compromises host defense, leading to overwhelming bacterial infection. Further, we found that the interruption of pulmonary ACE2 restitution in the model of bacterial lung infection delays the recovery process from neutrophilic lung inflammation. We observed the beneficial effects of recombinant ACE2 when administered to bacterially infected mouse lungs following an initial inflammatory response. In seeking to elucidate the mechanisms involved, we discovered that ACE2 inhibits neutrophil infiltration and lung inflammation by limiting IL-17 signaling by reducing the activity of the STAT3 pathway. The results suggest that the alteration of active ACE2 is not only a consequence of bacterial lung infection but also a critical component of host defense through modulation of the innate immune response to bacterial lung infection by regulating neutrophil influx.

Systemic effects of IL-17 in inflammatory arthritis

Inflammatory arthritis occurs in many diseases and is characterized by joint inflammation and damage. However, the inflammatory state in arthritis is commonly associated with systemic manifestations, which are generally linked to a poor prognosis. The pro-inflammatory cytokine IL-17 functions within a complex network of cytokines and contributes to the pathogenesis of various inflammatory diseases. Three IL-17 inhibitors have already been approved for the treatment of psoriasis, psoriatic arthritis, and ankylosing spondylitis. After a brief description of IL-17 and its local effects on joints, this Review focuses on the systemic effects of IL-17 in inflammatory arthritis. Increased circulating concentrations of bioactive IL-17 mediate changes in blood vessels, liver and cardiac and skeletal muscles. The effects of IL-17 on vascular and cardiac cells might contribute to the increased risk of cardiovascular events that occurs in all patients with inflammatory disorders. In the liver, IL-17 contributes to the high circulating concentrations of acute-phase proteins, such as C-reactive protein, and the appearance of liver lesions. In skeletal muscle, IL-17 contributes to muscle contractibility defects and weakness. Thus, targeting IL-17 might have beneficial effects at both local and systemic levels, and could also be proposed for the treatment of a wider range of inflammatory diseases.

Beneficial effects of andrographolide in a rat model of autoimmune myocarditis and its effects on PI3K/Akt pathway

The study is to investigate effects of andrographolide on experimental autoimmune myocarditis (EAM). Lewis rats were immunized on day 0 with porcine cardiac myosin to establish EAM. The EAM rats were treated with either andrographolide (25, 50, 100 mg/kg/day) or vehicle for 21 days. An antigen-specific splenocytes proliferation assay was performed by using the cells from control rats immunized with cardiac myosin. Survival rates, myocardial pathology and myocardial functional parameters (left ventricle end-diastolic pressure, ± dP/dt and left ventricular internal dimension) of EAM rats received andrographolide were significantly improved. Andrographolide treatment caused an decrease in the infiltration of CD3⁺ and CD14⁺ positive cells in myocardial tissue. Moreover, andrographolide treatment caused a reduction in the plasma levels of tumor necrosis factor-alpha, interleukin-17 (IL-17) and myosin-antibody, and an increase in the level of IL-10 in EAM rats. Oral administration of andrographolide resulted in the decreased expression of p-PI3K, p-Akt without any change of PI3K and Akt. Further results indicate andrographolide significantly inhibited myosin-induced proliferation in splenocytes, and this effect was inhibited by co-treatment of SC79 (Akt activator). Our data indicate andrographolide inhibits development of EAM, and this beneficial effect may be due to powerful anti-inflammatory activity and inhibitory effect on PI3K/Akt pathway.

Recent Developments on the Crosstalk Between STAT3 and Inflammation in Heart Function and Disease

The transcription factor STAT3 has a protective function in the heart. Until recently, the role of STAT3 in hypertension-induced cardiac hypertrophy was unsettled. Earlier studies revealed that global reduction of STAT3 activity reduced cardiac hypertrophy with hypertension, but caused a disruption of myofilaments and increased contractile dysfunction. However, newer studies with cardiomyocyte-specific deletion of STAT3 indicate that STAT3 does not cause cardiac hypertrophy with increased blood pressure. Rather, cardiac STAT3 is important for maintaining metabolic homeostasis, and loss of STAT3 in cardiomyocytes makes the heart more susceptible to chronic pathological insult, for example by disrupting glucose metabolism and protective signaling networks via the upregulation of certain microRNAs. This scenario has implications for understanding peripartum cardiomyopathy as well. In viral myocarditis, STAT3 opposes the initiation of the dilated phenotype by maintaining membrane integrity via the expression of dystrophin. STAT3 signaling was also found to attenuate myocarditis by polarizing macrophages to a less inflammatory phenotype. On the other hand, STAT3 contributes to immune-mediated myocarditis due to IL-6-induced complement component C3 production in the liver, as well as the differentiation of Th17 cells, which play a role in initiation and development of myocarditis. Besides canonical signaling pathways, unphosphorylated STAT3 (U-STAT3) and redox-activated STAT3 have been shown to couple to transcription in the heart. In addition, tissue signaling cytokines such as IL-22 and IL-17 have been proposed to have actions on the heart that involve STAT3, but are not fully defined. Understanding the novel and often protective aspects of STAT3 in the myocardium could lead to new therapeutic approaches to treat heart disease.

Ascitic Bacterial Composition Is Associated With Clinical Outcomes in Cirrhotic Patients With Culture-Negative and Non-neutrocytic Ascites

Ascites bacterial burden is associated with poor clinical outcomes in patients with end-stage liver disease. However, the impact of ascitic microbial composition on clinical course was still not clear. In this study, the ascitic microbiota composition of 100 cirrhotic patients with culture-negative and non-neutrocytic ascites were researched with 16S rRNA pyrosequencing and enterotype-like cluster analysis. Results: By characterizing the ascitic microbial composition, two distinct microbial clusters were observed, Cluster 1 (86 patients) and Cluster 2 (14 patients). Cluster 1 showed lower microbial richness than Cluster 2. At the phylum level, Cluster 1 had greater abundance of Bacteroidetes and Firmicutes, but less abundance of Proteobacteria and Actinobacteria than Cluster 2. At the family level, family Bacteroidales S24-7 group, Prevotellaceae, Lachnospiraceae, Lactobacillaceae, Rikenellaceae, and Vibrionaceae were found over-represented in Cluster 1. And family Acetobacteraceae, Erysipelotrichaceae, Rickettsiaceae, and Streptococcaceae were found enriched in Cluster 2. The levels of plasma cytokine IL-17A, IL-7, and PDGF-BB were found significantly higher in Cluster 1 than in Cluster 2. There were four OTUs closely correlated with plasma cytokines, which were OTU 140 and OTU 271 (both from Bacteroidales S24-7 group), OTU 68 (Veillonellaceae), and OTU 53 (Helicobacteraceae). Patients from Cluster 1 showed significant higher short-term mortality than patients from Cluster 2. Conclusion: Our study demonstrated that the microbial composition of culture-negative and non-neutrocytic ascites in cirrhotic patients is associated with short-term clinical outcomes. The results here offer a rational for the identification of patients with high risk, and provide references for selective use of prophylactic methods.

iNOS inhibits hair regeneration in obese diabetic (ob/ob) mice

Previous studies have shown that androgenic alopecia is associated with metabolic syndrome and diabetes. However, the detailed mechanism whereby diabetes causes alopecia still remains unclear. We focused on the inflammatory response that is caused by diabetes or obesity, given that inflammation is a risk factor for hair loss. Inducible nitric oxide synthase (iNOS) is known to be upregulated under conditions of acute or chronic inflammation. To clarify the potential role of iNOS in diabetes-related alopecia, we generated obese diabetic iNOS-deficient (ob/ob; iNOS-KO mice). We observed that ob/ob; iNOS-KO mice were potentiated for the transition from telogen (rest phase) to anagen (growth phase) in the hair cycle compared with iNOS-proficient ob/ob mice. To determine the effect of nitric oxide (NO) on the hair cycle, we administered an iNOS inhibitor intraperitoneally (compound 1400 W, 10 mg/kg) or topically (10% aminoguanidine) in ob/ob mice. We observed that iNOS inhibitors promoted anagen transition in ob/ob mice. Next, we administered an NO donor (S-nitrosoglutathione, GSNO), to test whether NO has the telogen elongation effects. The NO donor was sufficient to induce telogen elongation in wild-type mice. Together, our data indicate that iNOS-derived NO plays a role in telogen elongation under the inflammatory conditions associated with diabetes in mice.

Empagliflozin Limits Myocardial Infarction in Vivo and Cell Death in Vitro: Role of STAT3, Mitochondria, and Redox Aspects

Empagliflozin (EMPA), a drug approved for type 2 diabetes management, reduced cardiovascular death but is unknown if it reduces myocardial infarction. We sought to investigate: (i) the effect of EMPA on myocardial function and infarct size after ischemia/reperfusion in mice fed with western diet (WD), (ii) the underlying signaling pathways, (iii) its effects on cell survival in rat embryonic-heart-derived cardiomyoblasts (H9C2) and endothelial cells (ECs). To facilitate the aforementioned aims, mice were initially randomized in Control and EMPA groups and were subjected to 30 min ischemia and 2 h reperfusion. EMPA reduced body weight, blood glucose levels, and mean arterial pressure. Cholesterol, triglyceride, and AGEs remained unchanged. Left ventricular fractional shortening was improved (43.97 ± 0.92 vs. 40.75 ± 0.61%) and infarct size reduced (33.2 ± 0.01 vs. 17.6 ± 0.02%). In a second series of experiments, mice were subjected to the above interventions up to the 10th min of reperfusion and myocardial biopsies were obtained for assessment of the signaling cascade. STAT3 was increased in parallel with reduced levels of malondialdehyde (MDA) and reduced expression of myocardial iNOS and interleukin-6. Cell viability and ATP content were increased in H9C2 and in ECs. While, STAT3 phosphorylation is known to bestow infarct sparing properties through interaction with mitochondria, we observed that EMPA did not directly alter the mitochondrial calcium retention capacity (CRC); therefore, its effect in reducing myocardial infarction is STAT3 dependent. In conclusion, EMPA improves myocardial function and reduces infarct size as well as improves redox regulation by decreasing iNOS expression and subsequently lipid peroxidation as shown by its surrogate marker MDA. The mechanisms of action implicate the activation of STAT3 anti-oxidant and anti-inflammatory properties.

Inhibiting Interleukin 17 Can Ameliorate the Demyelination Caused by A. cantonensis via iNOS Inhibition

Angiostrongylus cantonensis (A. cantonensis) is an important food-borne parasitic disease. Previous study showed that A. cantonensis infection can cause demyelination in the central nerve system, but the mechanism of action has not been understood. To explore the mechanism and to look for effective therapeutic methods, interleukin 17A (IL-17A) and iNOS expressions were detected during A. cantonensis infection. In addition, IL-17A-neutralizing antibody was applied to treat A. cantonensis-infected mice. In our results, we found that IL-17A and iNOS RNA expressions increased gradually in the process of A. cantonensis infection. When infected mice were treated with IL-17A-neutralizing antibody, the pathologic changes of demyelination alleviated obviously, followed with the elevation of myelin basic protein (MBP) in the brain. In addition, the iNOS expression of the brain in infected animals also showed a decrease in astrocytes. Our study provided evidence that IL-17A may take part in the demyelination caused by A. cantonensis and inhibiting IL-17A expression can ameliorate the pathologic changes of demyelination. Moreover, the decreasing of iNOS expression may be the key reason for the effect of IL-17A inhibition on demyelination caused by A. cantonensis.

Potential humoral mediators of remote ischemic preconditioning in patients undergoing surgical coronary revascularization

Remote ischemic preconditioning (RIPC) by repeated brief cycles of limb ischemia/reperfusion may reduce myocardial ischemia/reperfusion injury and improve patients‘ prognosis after elective coronary artery bypass graft (CABG) surgery. The signal transducer and activator of transcription (STAT)5 activation in left ventricular myocardium is associated with RIPC´s cardioprotection. Cytokines and growth hormones typically activate STATs and could therefore act as humoral transfer factors of RIPC´s cardioprotection. We here determined arterial plasma concentrations of 25 different cytokines, growth hormones, and other factors which have previously been associated with cardioprotection, before (baseline)/after RIPC or placebo (n = 23/23), respectively, and before/after ischemic cardioplegic arrest in CABG patients. RIPC-induced protection was reflected by a 35% reduction of serum troponin I release. With the exception of interleukin-1α, none of the humoral factors changed in their concentrations after RIPC or placebo, respectively. Interleukin-1α, when normalized to baseline, increased after RIPC (280 ± 56%) but not with placebo (97 ± 15%). The interleukin-1α concentration remained increased until after ischemic cardioplegic arrest and was also higher than with placebo in absolute concentrations (25 ± 6 versus 16 ± 3 pg/mL). Only interleukin-1α possibly fulfills the criteria which would be expected from a substance to be released in response to RIPC and to protect the myocardium during ischemic cardioplegic arrest.

EphrinB2 Regulates Cardiac Fibrosis Through Modulating the Interaction of Stat3 and TGF-β/Smad3 Signaling

RATIONALE

Cardiac fibrosis is a common feature in left ventricular remodeling that leads to heart failure, regardless of the cause. EphrinB2 (erythropoietin-producing hepatoma interactor B2), a pivotal bidirectional signaling molecule ubiquitously expressed in mammals, is crucial in angiogenesis during development and disease progression. Recently, EphrinB2 was reported to protect kidneys from injury-induced fibrogenesis. However, its role in cardiac fibrosis remains to be clarified.

OBJECTIVE

We sought to determine the role of EphrinB2 in cardiac fibrosis and the underlying mechanisms during the pathological remodeling process.

METHODS AND RESULTS

EphrinB2 was highly expressed in the myocardium of patients with advanced heart failure, as well as in mouse models of myocardial infarction and cardiac hypertrophy induced by angiotensin II infusion, which was accompanied by myofibroblast activation and collagen fiber deposition. In contrast, intramyocardial injection of lentiviruses carrying EphrinB2-shRNA ameliorated cardiac fibrosis and improved cardiac function in mouse model of myocardial infarction. Furthermore, in vitro studies in cultured cardiac fibroblasts demonstrated that EphrinB2 promoted the differentiation of cardiac fibroblasts into myofibroblasts in normoxic and hypoxic conditions. Mechanistically, the profibrotic effect of EphrinB2 on cardiac fibroblast was determined via activating the Stat3 (signal transducer and activator of transcription 3) and TGF-β (transforming growth factor-β)/Smad3 (mothers against decapentaplegic homolog 3) signaling. We further determined that EphrinB2 modulated the interaction between Stat3 and Smad3 and identified that the MAD homology 2 domain of Smad3 and the coil-coil domain and DNA-binding domain of Stat3 mediated the interaction.

CONCLUSIONS

This study uncovered a previously unrecognized profibrotic role of EphrinB2 in cardiac fibrosis, which is achieved through the interaction of Stat3 with TGF-β/Smad3 signaling, implying a promising therapeutic target in fibrotic diseases and heart failure.