C1q/TNF-related protein-9 promotes macrophage polarization and improves cardiac dysfunction after myocardial infarction

CTRP9 alleviates diet induced obesity through increasing lipolysis mediated by enhancing autophagy-initiation complex formation

Recently, emerging evidence has suggested that obesity become a prevalent health threat worldwide. Reportedly, CTRP9 can ameliorate HFD induced obesity. However, the molecular mechanism underlying the role of CTRP9 in obesity remains elusive. In this study, we reported its major function in the regulation of lipolysis. First, we found that the expression of CTRP9 was decreased in mature adipocytes and white adipose tissue of obese mice. Then, we showed that overexpression adipose tissue CTRP9 alleviated diet-induced obesity and adipocytes hypertrophy, improved glucose intolerance and raised energy expenditure. Moreover, CTRP9 increased the lipolysis in vitro and vivo. Additionally, we determined that CTRP9 enhanced autophagy flux in adipocytes. Intriguingly, knock down Beclin1 by SiRNA abolished the effect of CTRP9 on lipolysis. Mechanically, CTRP9 enhanced the expression of SNX26. We demonstrated that SNX26 was a component of the ATG14L-Beclin1-VPS34 complex and enhanced the assembly of the autophagy-initiation complex. Collectively, our results suggested that CTRP9 alleviated diet induced obesity through enhancing lipolysis mediated by autophagy-initiation complex formation.

Macrophage-mediated heart repair and remodeling: A promising therapeutic target for post-myocardial infarction heart failure

Heart failure (HF) remains prevalent in patients who survived myocardial infarction (MI). Despite the accessibility of the primary percutaneous coronary intervention and medications that alleviate ventricular remodeling with functional improvement, there is an urgent need for clinicians and basic scientists to further reveal the mechanisms behind post-MI HF as well as investigate earlier and more efficient treatment after MI. Growing numbers of studies have highlighted the crucial role of macrophages in cardiac repair and remodeling following MI, and timely intervention targeting the immune response via macrophages may represent a promising therapeutic avenue. Recently, technology such as single-cell sequencing has provided us with an updated and in-depth understanding of the role of macrophages in MI. Meanwhile, the development of biomaterials has made it possible for macrophage-targeted therapy. Thus, an overall and thorough understanding of the role of macrophages in post-MI HF and the current development status of macrophage-based therapy will assist in the further study and development of macrophage-targeted treatment for post-infarction cardiac remodeling. This review synthesizes the spatiotemporal dynamics, function, mechanism and signaling of macrophages in the process of HF after MI, as well as discusses the emerging bio-materials and possible therapeutic agents targeting macrophages for post-MI HF.

M2 macrophage-derived exosomes promote angiogenesis and improve cardiac function after myocardial infarction

BACKGROUND

Myocardial infarction (MI) is a major cause of mortality and morbidity worldwide. The intercellular communication in post-infarction angiogenesis remains unclear.

METHODS

In this study, we explored the role and mechanism of action of M2 macrophage-derived exosomes (M2-exos) in angiogenesis after MI. M2-exos were harvested and injected intramyocardially at the onset of MI. Two distinct endothelial cells (ECs) were cultured with M2-exos to explore the direct effects on angiogenesis.

RESULTS

We showed that M2-exos improved cardiac function, reduced infarct size, and enhanced angiogenesis after MI. Moreover, M2-exos promoted angiogenesis in vitro; the molecules loaded in the vesicles were responsible for its proangiogenic effects. We further validated that higher abundance of miR-132-3p in M2-exos, which recapitulate their functions, was required for the cardioprotective effects exerted by M2-exos. Mechanistically, miR-132-3p carried by M2-exos down-regulate the expression of THBS1 through direct binding to its 3´UTR and the proangiogenic effects of miR-132-3p were largely reversed by THBS1 overexpression.

CONCLUSION

Our findings demonstrate that M2-exos promote angiogenesis after MI by transporting miR-132-3p to ECs, and by binding to THBS1 mRNA directly and negatively regulating its expression. These findings highlight the role of M2-exos in cardiac repair and provide novel mechanistic understanding of intercellular communication in post-infarction angiogenesis.

The m6A methylation enzyme METTL14 regulates myocardial ischemia/reperfusion injury through the Akt/mTOR signaling pathway

Herein, we investigated the role of the m6A methylation enzyme METTL14 in regulating myocardial ischemia/reperfusion injury (IR/I) through the Akt/mTOR signaling pathway and related biological mechanisms. Enzyme-linked immunosorbent assay (ELISA) and fluorescence quantitative polymerase chain reaction (qPCR) were performed to detect the m6A mRNA and METTL3, METTL14, WTAP, and KIAA1429 levels in a mouse myocardial IR/I model. An oxygen-glucose deprivation/reperfusion (OGD/R) model was constructed by transfecting neonatal rat cardiomyocytes (NRCM) with METTL14-knockdown lentivirus. METTL14, Bax, and cleaved-caspase3 mRNA expression levels were detected using fluorescence qPCR. Apoptosis was detected using TUNEL staining. After the IR/I surgery following the adeno-associated virus injection, the METTL14 mRNA and apoptosis-related BAX/BCL2 protein expression was detected using fluorescence qPCR and western blotting, respectively. Degree of cell necrosis was detected using an LDH assay. The oxidative stress response of the myocardial tissue was detected, and IL-6 and IL-1β serum levels were detected using ELISAs. The mice injected with METTL14-knockdown AAV9 adeno-associated virus underwent IR/I surgery after the injection of an Akt/mTOR pathway inhibitor (MK2206) into the myocardial layer. Elevated mRNA m6A modification and m6A methyltransferase METTL14 levels were observed in the IR/I-injured mouse heart tissues. METTL14 knockdown significantly inhibited the OGD/R- and IR/I-induced apoptosis and necrosis in cardiac myocytes, inhibited IR/I-induced oxidative stress and inflammatory factor secretion, and activated the Akt/ mTOR pathway in vitro and in vivo. Akt/mTOR pathway inhibition significantly attenuated the alleviating effect of METTL14 knockdown on myocardial IR/I injury-induced apoptosis. Knocking down m6A methylase METTL14 inhibits IR/I-induced myocardial apoptosis and necrosis, inhibits myocardial oxidative stress and secretion of inflammatory cytokines, and activates the Akt/mTOR signaling pathway. Hence, METTL14 regulated myocardial apoptosis and necrosis in mice with IR/I through the Akt/mTOR signaling pathway.

Nicorandil-Pretreated Mesenchymal Stem Cell-Derived Exosomes Facilitate Cardiac Repair After Myocardial Infarction via Promoting Macrophage M2 Polarization by Targeting miR-125a-5p/TRAF6/IRF5 Signaling Pathway

Background

Exosomes derived from bone marrow mesenchymal stem cells (MSC-exo) have been considered as a promising cell-free therapeutic strategy for ischemic heart disease. Cardioprotective drug pretreatment could be an effective approach to improve the efficacy of MSC-exo. Nicorandil has long been used in clinical practice for cardioprotection. This study aimed to investigate whether the effects of exosomes derived from nicorandil pretreated MSC (MSCNIC-exo) could be enhanced in facilitating cardiac repair after acute myocardial infarction (AMI).

Methods

MSCNIC-exo and MSC-exo were collected and injected into the border zone of infarcted hearts 30 minutes after coronary ligation in rats. Macrophage polarization was detected 3 days post-infarction, cardiac function as well as histological pathology were measured on the 28th day after AMI. Macrophages were separated from the bone marrow of rats for in vitro model. Exosomal miRNA sequencing was conducted to identify differentially expressed miRNAs between MSCNIC-exo and MSC-exo. MiRNA mimics and inhibitors were transfected to MSCs or macrophages to explore the specific mechanism.

Results

Compared to MSC-exo, MSCNIC-exo showed superior therapeutic effects on cardiac functional and structural recovery after AMI and markedly elevated the ratio of CD68+ CD206+/ CD68+cells in infarcted hearts 3 days post-infarction. The notable ability of MSCNIC-exo to promote macrophage M2 polarization was also confirmed in vitro. Exosomal miRNA sequencing and both in vivo and in vitro experiments identified and verified that miR-125a-5p was an effector of the roles of MSCNIC-exo in vivo and in vitro. Furthermore, we found miR-125a-5p promoted macrophage M2 polarization by inhibiting TRAF6/IRF5 signaling pathway.

Conclusion

This study suggested that MSCNIC-exo could markedly facilitate cardiac repair post-infarction by promoting macrophage M2 polarization by upregulating miR-125a-5p targeting TRAF6/IRF5 signaling pathway, which has great potential for clinical translation.

A review on regulation of DNA methylation during post-myocardial infarction

Myocardial infarction (MI) imposes a huge medical and economic burden on society, and cardiac repair after MI involves a complex series of processes. Understanding the key mechanisms (such as apoptosis, autophagy, inflammation, and fibrosis) will facilitate further drug development and patient treatment. Presently, a substantial body of evidence suggests that the regulation of epigenetic processes contributes to cardiac repair following MI, with DNA methylation being among the notable epigenetic factors involved. This article will review the research on the mechanism of DNA methylation regulation after MI to provide some insights for future research and development of related drugs.

CTRP6 promotes the macrophage inflammatory response, and its deficiency attenuates LPS-induced inflammation

Macrophages play critical roles in inflammation and tissue homeostasis, and their functions are regulated by various autocrine, paracrine, and endocrine factors. We have previously shown that CTRP6, a secreted protein of the C1q family, targets both adipocytes and macrophages to promote obesity-linked inflammation. However, the gene programs and signaling pathways directly regulated by CTRP6 in macrophages remain unknown. Here, we combine transcriptomic and phosphoproteomic analyses to show that CTRP6 activates inflammatory gene programs and signaling pathways in mouse bone marrow-derived macrophages (BMDMs). Treatment of BMDMs with CTRP6 upregulated proinflammatory, and suppressed the antiinflammatory, gene expression. We also showed that CTRP6 activates p44/42-MAPK, p38-MAPK, and NF-κB signaling pathways to promote inflammatory cytokine secretion from BMDMs, and that pharmacologic inhibition of these signaling pathways markedly attenuated the effects of CTRP6. Pretreatment of BMDMs with CTRP6 also sensitized and potentiated the BMDMs response to lipopolysaccharide (LPS)-induced inflammatory signaling and cytokine secretion. Consistent with the metabolic phenotype of proinflammatory macrophages, CTRP6 treatment induced a shift toward aerobic glycolysis and lactate production, reduced oxidative metabolism, and elevated mitochondrial reactive oxygen species production in BMDMs. Importantly, in accordance with our in vitro findings, BMDMs from CTRP6-deficient mice were less inflammatory at baseline and showed a marked suppression of LPS-induced inflammatory gene expression and cytokine secretion. Finally, loss of CTRP6 in mice also dampened LPS-induced inflammation and hypothermia. Collectively, our findings suggest that CTRP6 regulates and primes the macrophage response to inflammatory stimuli and thus may have a role in modulating tissue inflammatory tone in different physiological and disease contexts.

CEBPD REGULATES OXIDATIVE STRESS AND INFLAMMATORY RESPONSES IN HYPERTENSIVE CARDIAC REMODELING

ABSTRACT

Hypertension seems to inevitably cause cardiac remodeling, increasing the mortality of patients. This study aimed to explore the molecular mechanism of CCAAT/enhancer-binding protein delta (CEBPD)-mediated oxidative stress and inflammation in hypertensive cardiac remodeling. The hypertensive murine model was established through angiotensin-II injection, and hypertensive mice underwent overexpressed CEBPD vector injection, cardiac function evaluation, and observation of histological changes. The cell model was established by angiotensin-II treatment and transfected with overexpressed CEBPD vector. Cell viability and surface area and oxidative stress (reactive oxygen species/superoxide dismutase/lactate dehydrogenase/malondialdehyde) were assessed, and inflammatory factors (TNF-α/IL-1β/IL-6/IL-10) were determined both in vivo and in vitro . The levels of CEBPD, miR-96-5p, inositol 1,4,5-trisphosphate receptor 1 (IP3R), natriuretic peptide B, and natriuretic peptide A, collagen I, and collagen III in tissues and cells were determined. The binding relationships of CEBPD/miR-96-5p/IP3R 3' untranslated region were validated. CEBPD was reduced in cardiac tissue of hypertensive mice, and CEBPD upregulation improved cardiac function and attenuated fibrosis and hypertrophy, along with reductions of reactive oxygen species/lactate dehydrogenase/malondialdehyde/TNF-α/IL-1β/IL-6 and increases in superoxide dismutase/IL-10. CEBPD enriched on the miR-96-5p promoter to promote miR-96-5p expression, whereas CEBPD and miR-96-5p negatively regulated IP3R. miR-96-5p silencing/IP3R overexpression reversed the alleviative role of CEBPD overexpression in hypertensive mice. In summary, CEBPD promoted miR-96-5p to negatively regulate IP3R expression to inhibit oxidative stress and inflammation, thereby alleviating hypertensive cardiac remodeling.

α-Lipoic acid alleviates myocardial injury and induces M2b macrophage polarization after myocardial infarction via HMGB1/NF-kB signaling pathway

BACKGROUND

Myocardial infarction (MI) is a serious cardiovascular disease with a poor prognosis. Macrophages are the predominant immune cells in patients with MI and macrophage regulation during the different phases of MI has important consequences for cardiac recovery. Alpha-lipoic acid (ALA) plays a critical role in MI by modulating the number of cardiomyocytes and macrophages.

METHODS

MI mice were generated by ligating the left anterior descending coronary artery. Macrophages were exposed to hypoxia to establish a hypoxia model and M1 polarization was induced by LPS and IFN-γ. Different groups of macrophages and MI mice were treated with ALA. The cardiomyocytes were treated with various macrophage supernatants and the cardiac function, cytokine levels, and pathology were also analyzed. Factors related to apoptosis, autophagy, reactive oxygen species (ROS), and the mitochondrial membrane potential (MMP) were assessed. Finally, the HMGB1/NF-κB pathway was identified.

RESULTS

ALA promoted M2b polarization in normal cells and suppressed inflammatory cytokines during hypoxia. ALA inhibited ROS and MMP production in vitro. Supernatants containing ALA inhibited apoptosis and autophagy in hypoxic cardiomyocytes. Moreover, ALA suppressed the HMGB1/NF-κB pathway in macrophages, which may be a potential mechanism for attenuating MI.

CONCLUSION

ALA alleviates MI and induces M2b polarization via the HMGB1/NF-κB pathway, impeding inflammation, oxidation, apoptosis, and autophagy, and might be a potential strategy for MI treatment.

CTRP family in diseases associated with inflammation and metabolism: molecular mechanisms and clinical implication

C1q/tumor necrosis factor (TNF) related proteins (CTRPs) is a newly discovered adipokine family with conservative structure and ubiquitous distribution and is secreted by adipose tissues. Recently, CTRPs have attracted increasing attention due to the its wide-ranging effects upon inflammation and metabolism. To-date, 15 members of CTRPs (CTRP1-15) with the characteristic C1q domain have been characterized. Earlier in-depth phenotypic analyses of mouse models of CTRPs deficiency have also unveiled ample function of CTRPs in inflammation and metabolism. This review focuses on the rise of CTRPs, with a special emphasis on the latest discoveries with regards to the effects of the CTRP family on inflammation and metabolism as well as related diseases. We first introduced the structure of characteristic domain and polymerization of CTRPs to reveal its pleiotropic biological functions. Next, intimate association of CTRP family with inflammation and metabolism, as well as the involvement of CTRPs as nodes in complex molecular networks, were elaborated. With expanding membership of CTRP family, the information presented here provides new perspectives for therapeutic strategies to improve inflammatory and metabolic abnormalities.

Embelin attenuates lipopolysaccharide-induced acute kidney injury through the inhibition of M1 macrophage activation and NF-κB signaling in mice

Septic acute kidney injury (AKI) is commonly associated with renal dysfunction and high mortality in patients. Owing to the rapid and violent occurrence of septic AKI with inflammation, there are no effective therapies to clinically treat it. Embelin, a natural product, has a potential regulatory role in immunocytes. However, the role and mechanism of embelin in septic AKI remains unknown. This study aimed to elucidate the role of embelin in macrophage regulation in lipopolysaccharide (LPS)-induced septic AKI. Embelin was intraperitoneally administered to mice after LPS injection. And bone marrow-derived macrophages (BMDMs) were subsequently isolated from the mice to explore the immunomodulatory role of embelin in macrophages. We found that embelin attenuated renal dysfunction and pathological renal damage in the LPS-induced sepsis mouse model. Molecular docking predicted that embelin could bind to phosphorylated NF-κB p65 at the ser536 site. Embelin inhibited the translocation of NF-κB p65 via phosphorylation at ser536 in LPS-induced AKI. It also reduced the secretion of IL-1β and IL-6 and increased the secretion of IL-10 and Arg-1 of BMDMs and mice after LPS stimulation, indicating that embelin suppressed macrophage M1 activation in LPS-induced AKI. Therefore, embelin attenuated LPS-induced septic AKI by suppressing NF-κB p65 at ser536 in activated macrophages. This study preclinically suggests a therapeutic role of embelin in septic AKI.

Complement 1q/Tumor Necrosis Factor-Related Proteins (CTRPs): Structure, Receptors and Signaling

Adiponectin and the other 15 members of the complement 1q (C1q)/tumor necrosis factor (TNF)-related protein (CTRP) family are secreted proteins composed of an N-terminal variable domain followed by a stalk region and a characteristic C-terminal trimerizing globular C1q (gC1q) domain originally identified in the subunits of the complement protein C1q. We performed a basic PubMed literature search for articles mentioning the various CTRPs or their receptors in the abstract or title. In this narrative review, we briefly summarize the biology of CTRPs and focus then on the structure, receptors and major signaling pathways of CTRPs. Analyses of CTRP knockout mice and CTRP transgenic mice gave overwhelming evidence for the relevance of the anti-inflammatory and insulin-sensitizing effects of CTRPs in autoimmune diseases, obesity, atherosclerosis and cardiac dysfunction. CTRPs form homo- and heterotypic trimers and oligomers which can have different activities. The receptors of some CTRPs are unknown and some receptors are redundantly targeted by several CTRPs. The way in which CTRPs activate their receptors to trigger downstream signaling pathways is largely unknown. CTRPs and their receptors are considered as promising therapeutic targets but their translational usage is still hampered by the limited knowledge of CTRP redundancy and CTRP signal transduction.

Propionate alleviated post-infarction cardiac dysfunction by macrophage polarization in a rat model

BACKGROUND

The propionate (C3), the important components of short-chain fatty acids (SCFAs), had the effect of inhibiting pro-inflammatory macrophages. Earlier macrophages phenotypic transition from pro-inflammatory M1 to reparative M2 in early stage was a central juncture of cardiac dysfunction mitigation after myocardial infarction (MI).

METHODS

160 Sprague-Dawley rats were assigned to 4 groups: sham group (n = 40), sham + C3 group (n = 40), MI group (n = 40) and MI + C3 group (n = 40). The rats in sham + C3 and MI + C3 group were treated with oral sodium propionate (200 mM), and equivalent concentration of sodium chloride was administered in sham and MI group as control. After 7 days of propionate adaptive feeding, rats were anesthetized and induced the MI by coronary occlusion. The classification of macrophages, the level of inflammatory factors and inflammatory signaling were estimated at 3rd days after thoracotomy, and the extent of myocardial fibrosis was evaluated at 7th and 28th days after operation. Echocardiography was estimated on 28th day after surgery. RAW264.7 cells, stimulated by LPS + IFN-γ with or without propionate, were harvested for western blot and supernatants were collected for cytokine analysis by ELISA.

RESULTS

Propionate administration reduced the MI-induced myocardial fibrosis in infarcted border and attenuated cardiac function deterioration compared with MI group. In comparison with MI group, propionate promoted macrophages reduction, macrophage M2-like polarization, and inflammatory cytokines decrease in infarcted border zone following MI, which partly depends on the inhibition of JNK/P38/NFκB signaling pathways.

CONCLUSIONS

Oral propionate in early stage, as a nutritional intervention, alleviated post-MI chronic cardiac remodeling and cardiac dysfunction at least in part by modulating macrophages polarization and pro-inflammatory cytokine, which were associated with reduction of JNK/P38/NFκB phosphorylation.

NAD+ attenuates cardiac injury after myocardial infarction in diabetic mice through regulating alternative splicing of VEGF in macrophages

Diabetic mellitus (DM) complicated with myocardial infarction (MI) is a serious clinical issue that remained poorly comprehended. The aim of the present study was to investigate the role of NAD⁺ in attenuating cardiac damage following MI in diabetic mice. The cardiac dysfunction in DM mice with MI was more severe compared with the non-diabetic mice and NAD⁺ administration could significantly improve the cardiac function in both non-diabetic and diabetic mice after MI for both 7 days and 28 days. Moreover, application of NAD⁺ could markedly reduce the cardiac injury area of DM complicated MI mice. Notably, the level of NAD⁺ was robustly decreased in the cardiac tissue of MI mice, which was further reduced in the DM complicated mice and NAD⁺ administration could significantly restore the NAD⁺ level. Furthermore, NAD⁺ was verified to facilitate the angiogenesis in the MI area of both diabetic mice and non-diabetic mice by microfil perfusion assay and immunofluorescence. Additionally, we demonstrated that NAD⁺ promoted cardiac angiogenesis after myocardial infarction in diabetic mice by promoting the M2 polarization of macrophages. At the molecular level, NAD⁺ promoted the secretion of VEGF in macrophages and therefore facilitating migration and tube formation of endothelial cells. Mechanistically, NAD⁺ was found to promote the generation of pro-angionesis VEGF₁₆₅ and inhibit the generation of anti-angionesis VEGF_165b via regulating the alternative splicing factors of VEGF (SRSF1 and SRSF6) in macrophages. The effects of NAD⁺ were readily reversible on deficiency of it. Collectively, our data showed that NAD⁺ could attenuate myocardial injury via regulating the alternative splicing of VEGF and promoting angiogenesis in diabetic mice after myocardial infarction. NAD⁺ administration may therefore be considered a potential new approach for the treatment of diabetic patients with myocardial infarction.

Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Attenuate Myocardial Infarction Injury via miR-24-3p-Promoted M2 Macrophage Polarization

Exosomes derived from human umbilical cord mesenchymal stem cells (UMSC-Exos) have shown encouraging effects in regulating inflammation and attenuating myocardial injury. Macrophages are regulated dynamically in response to environmental cues. However, the underlying mechanisms by which UMSC-Exos regulate macrophage polarization are still not well understood. Herein, it is aimed to explore the effects of UMSC-Exos on macrophage polarization and their roles in cardiac repair after myocardial infarction (MI). These results show that UMSC-Exos improve cardiac function by increasing M2 macrophage polarization and reducing excessive inflammation. RNA-sequencing results identify Plcb3 as a key gene involved in UMSC-Exo-facilitated M2 macrophage polarization. Further bioinformatic analysis identifies exosomal miR-24-3p as a potential effector mediating Plcb3 downregulation in macrophages. Increasing miR-24-3p expression in macrophages effectively enhances M2 macrophage polarization by suppressing Plcb3 expression and NF-κB pathway activation in the inflammatory environment. Furthermore, reducing miR-24-3p expression in UMSC-Exos attenuates the effects of UMSC-Exos on M2 macrophage polarization. This study demonstrates that the cardiac therapeutic effects of UMSC-Exos are at least partially through promoting M2 macrophage polarization in an inflammatory microenvironment. Mechanistically, exosomal miR-24-3p is found to inhibit Plcb3 expression and NF-κB pathway activation to promote M2 macrophage polarization.

Effect of C1q/TNF-Related Protein 9 on Coronary Artery Calcification: An Observational Study

Coronary artery calcification (CAC) increases the risk of acute coronary syndrome. This study examined the correlation between C1q/TNF-related protein 9 (CTRP9) and CAC and explored CTRP9 as a biomarker for prognosis. We divided 275 patients with coronary heart disease into four groups. In order to balance the baseline confounding factors, propensity score matching (PSM) was performed to match CAC patients with non-CAC patients in a 1:1 ratio. Optical coherence tomography (OCT) calcification scoring was performed in 126 patients with CAC. Moreover, 140 patients who underwent OCT were followed-up for 9 months for analysis of the correlation between CTRP9 levels and clinical prognosis. Based on OCT calcification scores, 126 patients with CAC were divided into the 0–2 and 3–4 groups. Plasma CTRP9 levels were significantly lower in the type 2 diabetes mellitus (T2DM), CAC and CAC with T2DM groups than in the control group. CTRP9 played roles as a protective factor and potential predictor in CAC severity. The AUC of the OCT calcification score 3–4 group predicted by the plasma CTRP9 level was 0.766. During the follow-up period, the cumulative event-free survival rate was significantly lower in the low-level CTRP9 (L-CTRP9) group than in the high-level (H-CTRP9) group, and the incidence of major endpoint events was significantly higher in the L-CTRP9 group than in the H-CTRP9 group. CTRP9 can be a valuable biomarker for CAC occurrence and severity and can predict patients’ clinical prognosis.

Effects of Metabolism on Macrophage Polarization Under Different Disease Backgrounds

Macrophages are versatile immune cells associated with various diseases, and their phenotypes and functions change on the basis of the surrounding environments. Reprogramming of metabolism is required for the proper polarization of macrophages. This review will focus on basic metabolic pathways, the effects of key enzymes and specific products, relationships between cellular metabolism and macrophage polarization in different diseases and the potential prospect of therapy targeted key metabolic enzymes. In particular, the types and characteristics of macrophages at the maternal-fetal interface and their effects on a successful conception will be discussed.

Upregulation of SPI1 during myocardial infarction aggravates cardiac tissue injury and disease progression through activation of the TLR4/NFκB axis

OBJECTIVE

Spleen focus forming virus proviral integration oncogene (SPI1) belongs to the ETS family of transcription factors participating in an array of cellular processes such as inflammation and cell apoptosis. This research focused on the role of SPI1 in the myocardial infarction (MI).

METHODS

A murine model of MI was established. HL-1 cells were exposed to hypoxic treatment to simulate an MI-like condition. Tissue injury, inflammatory infiltration, and fibrosis in the cardiac tissues, and the apoptosis and the production of inflammation-related factors in cells were examined. Expression of SPI1 was determined. The downstream targets of SPI1 were identified by bioinformatics tools and luciferase assays. Artificial up- or downregulation of SPI1 and toll like receptor 4 (TLR4) were induced to examine their involvements in MI progression.

RESULTS

SPI1 was expressed at high levels in the cardiac tissues of MI mice and in hypoxia-induced HL-1 cells. SPI1 downregulation reduced apoptosis and the production of inflammatory cytokines in the hypoxia-induced HL-1 cells. SPI1 bound to TLR4 promoter to induce transcriptional activation. TLR4 induced NFκB phosphorylation and blocked the protective role of SPI1 silencing in cells. In vivo, SPI1 inhibition restored the cardiac function and ameliorated MI-induced inflammation and fibrosis in mice. The protective role of SPI1 inhibition in mice was blocked by TLR4 activation. Aberrant upregulation of SPI1 was caused by the reduced DNA methylation during MI.

CONCLUSION

This study demonstrated that upregulation of SPI1, caused by reduced DNA methylation, augmented development of myocardial infarction by activating the TLR4/NFκB axis.

C1q/Tumor Necrosis Factor-Related Protein 9: Basics and Therapeutic Potentials

C1q/tumor necrosis factor-related protein 9 (CTRP9) is a newly discovered adipokine that is the closest paralog of adiponectin. Proteolytic cleavage of CTRP9 leads to the release of the globular domain (gCTRP9), which serves as the major circulating subtype. After binding with adiponectin receptor 1 (AdipoR1) and N-cadherin, CTRP9 activates various signaling pathways to regulate glucose and lipid metabolism, vasodilation and cell differentiation. Throughout human development and adult life, CTRP9 controls many biological phenomena. simultaneously, abnormal gene or protein expression of CTRP9 is accompanied by a wide range of human pathological phenomena. In this review, we briefly introduce CTRP9 and its associated signaling pathways and physiological functions, which may be helpful in the understanding of the occurrence of diseases. Moreover, we summarize the broader research prospects of CTRP9 and advances in therapeutic intervention. In recent years, CTRP9 has attracted extensive attention due to its role in the pathogenesis of various diseases, providing further avenues for its exploitation as a potential biomarker or therapeutic target.

The Role of Anti-Inflammatory Adipokines in Cardiometabolic Disorders: Moving beyond Adiponectin

The global burden of obesity has multiplied owing to its rapidly growing prevalence and obesity-related morbidity and mortality. In addition to the classic role of depositing extra energy, adipose tissue actively interferes with the metabolic balance by means of secreting bioactive compounds called adipokines. While most adipokines give rise to inflammatory conditions, the others with anti-inflammatory properties have been the novel focus of attention for the amelioration of cardiometabolic complications. This review compiles the current evidence on the roles of anti-inflammatory adipokines, namely, adiponectin, vaspin, the C1q/TNF-related protein (CTRP) family, secreted frizzled-related protein 5 (SFRP5), and omentin-1 on cardiometabolic health. Further investigations on the mechanism of action and prospective human trials may pave the way to their clinical application as innovative biomarkers and therapeutic targets for cardiovascular and metabolic disorders.

C1q tumor necrosis factor-related protein 1: a promising therapeutic target for atherosclerosis

ABSTRACT

Atherosclerosis serves as the pathological basis of most cardiovascular and cerebrovascular diseases. C1q tumor necrosis factor-related protein (CTRP1) is a 35-kDa glycoprotein synthesized by various tissues and cells, such as adipose tissue and macrophages. As an adiponectin paralog, CTRP1 signals through adiponectin receptor 1 (AdipoR1) and participates in a variety of pathophysiological processes. Circulating CTRP1 levels are significantly increased in patients with coronary artery disease. Importantly, CTRP1 was shown to accelerate the development of atherosclerosis by promoting vascular inflammation, macrophage foam cell formation and endothelial barrier dysfunction. This review focused on recent advances regarding the role of CTRP1 in atherogenesis with an emphasis on its potential as a novel biomarker and a promising therapeutic target for atherosclerosis-related diseases.

The Protective Role of Yin-Yang 1 in Cardiac Injury and Remodeling After Myocardial Infarction

Background Exploring potential therapeutic target is of great significance for myocardial infarction (MI) and post-MI heart failure. Transcription factor Yin-Yang 1 (YY1) is an essential regulator of apoptosis and angiogenesis, but its role in MI is unclear. Methods and Results The expression of YY1 was assessed in the C57BL/6J mouse heart following MI. Overexpression or silencing of YY1 in the mouse heart was achieved by adeno-associated virus 9 injection. The survival, cardiac function, and scar size, as well as the apoptosis, angiogenesis, cardiac fibrosis, T helper 2 lymphocyte cytokine production, and macrophage polarization were assessed. The effects of YY1 on Akt phosphorylation and vascular endothelial growth factor production were also investigated. The expression of YY1 in heart was significantly stimulated by MI. The survival rate, cardiac function, scar size, and left ventricular volume of mice were improved by YY1 overexpression but worsened by YY1 silencing. YY1 alleviated cardiac apoptosis and fibrosis, promoted angiogenesis, T helper 2 cytokine production, and M2 macrophage polarization in the post-MI heart, it also enhanced the tube formation and migration ability of endothelial cells. Enhanced Akt phosphorylation, along with the increased vascular endothelial growth factor levels were observed in presence of YY1 overexpression. Conclusions YY1 ameliorates cardiac injury and remodeling after MI by repressing cardiomyocyte apoptosis and boosting angiogenesis, which might be ascribed to the enhancement of Akt phosphorylation and the subsequent vascular endothelial growth factor up-regulation. Increased T helper 2 cytokine production and M2 macrophage polarization may also be involved in YY1's cardioprotective effects. These findings supported YY1 as a potential target for therapeutic investigation of MI.

Lcz696 Alleviates Myocardial Fibrosis After Myocardial Infarction Through the sFRP-1/Wnt/β-Catenin Signaling Pathway

Background: Lcz696 (ARNI, angiotensin receptor–neprilysin inhibitor; sacubitril/valsartan) shows an inhibitory effect on fibrosis after myocardial infarction (MI). However, the underlying signaling mechanisms are poorly understood. The Wnt/β-catenin signaling pathway is activated after MI and participates in the process of myocardial fibrosis. Here, we aimed to assess the efficacy of ARNI for alleviating myocardial fibrosis after MI and hypothesized that ARNI alleviates myocardial fibrosis by inhibiting the Wnt/β-catenin signaling pathway and overexpressing sFRP-1, an inhibitor of the Wnt/β-catenin signaling pathway.

Methods: Mice randomized at 1 week post-MI were administered lcz696 (60 mg/kg, n = 21), valsartan (30 mg/kg, n = 19), or corn oil (n = 13) orally for 4 weeks, while the sham-operated group received vehicle (corn oil, n = 19). Cardiac function and extent of myocardial fibrosis were measured. Western blotting and quantitative real-time polymerase chain reaction were used to detect the expression of Wnt/β-catenin pathway-related proteins. Furthermore, primary myocardial fibroblasts were stimulated with angiotensin II (Ang II) and cultured with lcz696 and the sFRP-1 inhibitor way316606 to detect the expression of Wnt/β-catenin pathway proteins.

Results: Both lcz696 and valsartan alleviated myocardial fibrosis and improved cardiac function, but lcz696 had superior efficiency compared to valsartan. Furthermore, β-catenin expression was inhibited and sFRP-1 was overexpressed after drug treatment, which could be significantly improved by lcz696 in mice. In addition, lcz696 inhibited β-catenin expression in AngII-stimulated myocardial fibroblasts, and β-catenin expression increased after the inhibition of sFRP-1.

Conclusion: ARNI alleviated cardiac fibrosis and cardiac remodeling by inhibiting the Wnt/β-catenin signaling pathway. In addition, ARNI can lead to overexpression of sFRP-1, which is an inhibitor of the Wnt/β-catenin signaling pathway. These results indicate a new therapeutic target of ARNI to improve myocardial fibrosis and prevent myocardial remodeling.

C1q/TNF-related protein 9 decreases cardiomyocyte hypoxia/reoxygenation-induced inflammation by inhibiting the TLR4/MyD88/NF-κB signaling pathway

C1q/TNF-related protein 9 (CTRP9) acts as an adipokine and has been reported to exert numerous biological functions, such as anti-inflammatory and anti-oxidative stress effects, in ischemic heart disease. In the present study, the role of CTRP9 in neonatal rat cardiomyocytes (NRCMs) following hypoxia/reoxygenation (H/R) and the underlying mechanism was investigated. Adenoviral vectors containing CTRP9 or green fluorescent protein were transfected into NRCMs. A H/R model was constructed 2 days after transfection by 2 h incubation under hypoxia followed by 4 h of reoxygenation. Lactate dehydrogenase (LDH), creatine kinase (CK) and CK-myocardial band (CK-MB) levels were detected by a biochemical analyzer using biochemical kits. In addition, cell viability was detected using trypan blue staining to determine the extent of cell injury. Inflammatory cytokines TNF-α, IL-6 and IL-10 were measured by ELISA. Western blotting and reverse transcription-quantitative PCR were used to evaluate the expression levels of CTRP9, toll-like receptor 4 (TLR4), myeloid differentiation primary response (MyD88) and NF-κB. The DNA binding activity of NF-κB was also detected using an electrophoretic mobility shift assay. The results indicated that transfection with adenoviral vectors containing CTRP9 could markedly enhance CTRP9 expression. CTRP9 overexpression increased cell viability and decreased the release of LDH, CK and CK-MB. In addition, CTRP9 overexpression reduced TNF-α and IL-6 levels whilst increasing IL-10 levels, but decreased the expression of TLR4, MyD88 and NF-κB. Furthermore, the DNA binding activity of NF-κB under H/R was also decreased by CTRP9 overexpression. In conclusion, the results of the present study suggested that CTRP9 could protect cardiomyocytes from H/R injury, which was at least partially due to the inhibition of the TLR4/MyD88/NF-κB signaling pathway to reduce the release of inflammatory cytokines.

Colchicine-Containing Nanoparticles Attenuates Acute Myocardial Infarction Injury by Inhibiting Inflammation

PURPOSE

Anti-inflammatory therapy is important for reducing myocardial injury after acute myocardial infarction (MI). New anti-inflammatory drugs and their mechanism are necessary to be explored to improve clinical efficacy. We aimed to improve the efficacy of colchicine on attenuating MI injury by nano-drug delivery systems and to investigate the mechanism of anti-inflammatory.

METHODS

A colchicine-containing delivery system based on calcium carbonate nanoparticles (ColCaNPs) was synthesized. The protection against MI by ColCaNPs was evaluated using an in vivo rat model established by ligating the left anterior descending coronary artery. Macrophage polarization and the levels of inflammatory cytokines were determined using immunohistochemistry, Western blot, and ELISA analysis.

RESULTS

ColCaNP treatment showed about a 45% reduction in myocardial infarct size and attenuating myocardial fibrosis compared with groups without drug intervention after MI. Furthermore, ColCaNPs significantly decreased the levels of CRP, TNF-α, and IL-1β in serum and the expression of proinflammatory cytokine in myocardial tissues after MI (p < 0.05). We also found that ColCaNPs notably restrained pyroptosis and inhibited inflammatory response by modulating on M1/M2 macrophage polarization and suppressing TLR4/NFκB/NLRP3 signal pathway.

CONCLUSION

Colchicine-containing nanoparticles can protect against MI injury in a clinically relevant rat model by reducing inflammation. In addition, calcium carbonate nanoparticles can increase the cardioprotective effects of colchicine.

Adenine Nucleotide Translocase 1 Expression Modulates the Immune Response in Ischemic Hearts

Adenine nucleotide translocase 1 (ANT1) transfers ATP and ADP over the mitochondrial inner membrane and thus supplies the cell with energy. This study analyzed the role of ANT1 in the immune response of ischemic heart tissue. Ischemic ANT1 overexpressing hearts experienced a shift toward an anti-inflammatory immune response. The shift was characterized by low interleukin (IL)-1β expression and M1 macrophage infiltration, whereas M2 macrophage infiltration and levels of IL-10, IL-4, and transforming growth factor (TGFβ) were increased. The modulated immune response correlated with high mitochondrial integrity, reduced oxidative stress, low left ventricular end-diastolic heart pressure, and a high survival rate. Isolated ANT1-transgenic (ANT1-TG) cardiomyocytes expressed low levels of pro-inflammatory cytokines such as IL-1α, tumor necrosis factor α, and TGFβ. However, they showed increased expression and cellular release of anti-inflammatory immunomodulators such as vascular endothelial growth factor. The secretome from ANT1-TG cardiomyocytes initiated stress resistance when applied to ischemic wild-type cardiomyocytes and endothelial cells. It additionally prevented macrophages from expressing pro-inflammatory cytokines. Additionally, ANT1 expression correlated with genes that are related to cytokine and growth factor pathways in hearts of patients with ischemic cardiomyopathy. In conclusion, ANT1-TG cardiomyocytes secrete soluble factors that influence ischemic cardiac cells and initiate an anti-inflammatory immune response in ischemic hearts.

Il12a Deletion Aggravates Sepsis-Induced Cardiac Dysfunction by Regulating Macrophage Polarization

Cardiac dysfunction is a well-recognized complication of sepsis and is associated with the outcome and prognosis of septic patients. Evidence suggests that Il12a participates in the regulation of various cardiovascular diseases, including heart failure, hypertension and acute myocardial infarction. However, the effects of Il12a in sepsis-induced cardiac dysfunction remain unknown. In our study, lipopolysaccharide (LPS) and cecal ligation and puncture (CLP) model were used to mimic sepsis, and cardiac Il12a expression was assessed. In addition, Il12a knockout mice were used to detect the role of Il12a in sepsis-related cardiac dysfunction. We observed for the first time that Il12a expression is upregulated in mice after LPS treatment and macrophages were the main sources of Il12a. In addition, our findings demonstrated that Il12a deletion aggravates LPS-induced cardiac dysfunction and injury, as evidenced by the increased serum and cardiac levels of lactate dehydrogenase (LDH) and cardiac creatine kinase-myocardial band (CK-MB). Moreover, Il12a deletion enhances LPS-induced macrophage accumulation and drives macrophages toward the M1 phenotype in LPS-treated mice. Il12a deletion also downregulated the activity of AMP-activated protein kinase (AMPK) but increased the phosphorylation levels of p65 (p-p65) and NF-κB inhibitor alpha (p-IκBα). In addition, Il12a deletion aggravates CLP-induced cardiac dysfunction and injury. Treatment with the AMPK activator AICAR abolishes the deterioration effect of Il12a deletion on LPS-induced cardiac dysfunction. In conclusion, Il12a deletion aggravated LPS-induced cardiac dysfunction and injury by exacerbating the imbalance of M1 and M2 macrophages. Our data provide evidence that Il12a may represent an attractive target for sepsis-induced cardiac dysfunction.

FGF21 alleviates chronic inflammatory injury in the aging process through modulating polarization of macrophages

Previous studies reported that FGF21 prolongs life span and delays the body senescence, but the mechanism is not clear. The present study was designed to investigate the effects of FGF21 on hepatic senescence in aging mice and further research the mechanism. The 14-month-old male mice were administered with PBS, FGF21 or metformin once daily for 6 months. Results showed that FGF21 alleviated liver injury and inhibited accumulation of senescence markers SASP, P53 and P16 in the livers of aging mice. Subsequently we found that the aging mice treated by FGF21 showed transition of type 1 macrophages (M1) to type 2 macrophages (M2) in the livers. Next, we used THP-1 macrophages triggered by LPS to study effects of FGF21 on macrophages. Macrophages triggered by LPS exhibited features of M1, but the addition of FGF21 decreased the expression of M1 markers, and promoted the macrophages to exhibit features of M2. Results showed that the effects of FGF21 on macrophages were associated with the AMPK pathway. After adding AMPK inhibitor, the effects of FGF21 were inhibited, which was associated with the NF-κB signaling pathway. Finally, co-culturing differentiated macrophages and hepatocytes, we found that the large amount of pro-inflammatory factors such as IL-6 promoted hepatocyte senescence, which exhibited enhanced P53, P16 and β-galactosidase. This was contrary to hepatocytes co-cultured with macrophages treated by FGF21. These results indicate that FGF21 alleviates hepatic senescence injury by modulating the polarization of macrophages through the AMPK /NF-κB signaling pathway.

The impacts of C1q/TNF-related protein-15 and adiponectin on Interleukin-6 and tumor necrosis factor-α in primary macrophages of patients with coronary artery diseases

Atherosclerosis is a progressive inflammatory disease characterized by the accumulation of lipids in the arterial wall. Inflammation plays a key role in the pathogenesis of atherosclerosis and some previous studies have shown the role of adipokines during the inflammatory process of atherosclerosis. Therefore, the present study aimed to evaluate the impacts of adiponectin and CTRP15 on inflammatory cytokines secretions from THP1 and primary macrophages.

METHODS

THP1 monocytes were differentiated to macrophages and primary monocytes were then isolated from patients with coronary artery disease and controls who were differentiated to macrophages. Macrophages were treated with LPS, LPS+adiponectin, and LPS+CTRP15.

RESULTS

Adiponectin and CTRP15 have reduced IL-6 and TNF-α secretions from LPS-induced THP1 macrophages, and the CTRP15 indicated a more potent anti-inflammatory property compared to adiponectin. In addition, adiponectin reduced cytokines' expressions and secretions in primary macrophages of both patient and control groups. However, CTRP15 has only reduced cytokines' expressions and secretions in controls and it was not able to ameliorate inflammation in macrophages of CAD patients.

CONCLUSION

The results of the present study indicate anti-inflammatory impact of adiponectin and CTRP15, while this property was stronger for CTRP15. In addition, it seems likely that anti-inflammatory CTRP15's impact on macrophages in the CAD patients was weaker than macrophages from the controls.

C1q/TNF-related protein-9 is elevated in hypertension and associated with the occurrence of hypertension-related atherogenesis

C1q-tumor necrosis factor-related protein-9 (CTRP9) is an important adipocytokine that is closely associated with cardiovascular disease. This study aimed to detect CTRP9 expression in hypertensive patients and mice and to analyze its effects on hypertension-related atherogenesis. First, circulating CTRP9 levels were detected in both nonhypertensive subjects and hypertensive patients. The results showed that plasma CTRP9 levels were increased in hypertension patients compared with control subjects and gradually elevated in the Grade I, Grade II, and Grade III groups. While nondipper state did not affect CTRP9 expression in hypertension patients. Hypertension patients with carotid atherosclerotic plaque (CAP) exhibited higher CTRP9 levels and the high CTRP9 group exhibited significantly higher CAP morbidity, CTRP9 levels were positively correlated with the occurrence of CAP. Then, effects of CTRP9 on angiotensin II (Ang II)-induced endothelial dysfunction were analyzed in vitro, and the results exhibited that treatment with Ang II significantly increased CTRP9 mRNA expression in endothelial cells (ECs), and downregulation of CTRP9 expression aggravated Ang II-induced endothelial dysfunction in ECs. Mice were infused with Ang II, and CTRP9 was also increased in Ang II-infused mice and mainly secreted by ECs. In Ang II-infused ApoE^-/- mice, treatment with recombinant CTRP9 significantly reduced atherosclerotic area and alleviated endothelial dysfunction. In conclusion, our results may found that CTRP9 delayed the progression of hypertension-related arteriosclerosis by alleviating endothelial dysfunction.

Nucleolin acts as the receptor for C1QTNF4 and supports C1QTNF4-mediated innate immunity modulation

The C1q and TNF related 4 (C1QTNF4) protein is a structurally unique member of the C1QTNF family, a family of secreted proteins that have structural homology with both complement C1q and the tumor necrosis factor superfamily. C1QTNF4 has been linked to the autoimmune disease systemic lupus erythematosus through genetic studies; however, its role in immunity and inflammation remains poorly defined and a cell surface receptor of C1QTNF4 has yet to be identified. Here we report identification of nucleolin as a cell surface receptor of C1QTNF4 using mass spectrometric analysis. Additionally, we present evidence that the interaction between C1QTNF4 and nucleolin is mediated by the second C1q-like domain of C1QTNF4 and the C terminus of nucleolin. We show that monocytes and B cells are target cells of C1QTNF4 and observe extensive binding to dead cells. Imaging flow cytometry experiments in monocytes show that C1QTNF4 becomes actively internalized upon cell binding. Our results suggest that nucleolin may serve as a docking molecule for C1QTNF4 and act in a context-dependent manner through coreceptors. Taken together, these findings further our understanding of C1QTNF4's function in the healthy immune system and how dysfunction may contribute to the development of systemic lupus erythematosus.

CTRP9 protects against MIA-induced inflammation and knee cartilage damage by deactivating the MAPK/NF-κB pathway in rats with osteoarthritis

C1q/TNF-related protein 9 (CTRP9), the closest paralog of adiponectin, has been reported to protect against inflammation-related diseases. However, its role in regulating osteoarthritis (OA) has not been fully elucidated. First, a rat model of OA was generated. Furthermore, rats with OA were injected with different doses of recombinant CTRP9 protein (rCTRP9), and the knee cartilage damage was evaluated. Finally, the phosphorylation of p38 and the secretion of matrix metalloproteinases (MMPs) were detected by Western blotting and enzyme-linked immunosorbent assay. Results revealed that CTRP9 was highly expressed in adipose tissue, followed by skeletal muscle and cartilage tissue, and less expressed in liver, kidney and lung. Moreover, the expression of CTRP9 significantly decreased in the monosodium iodoacetate (MIA) group in the knee cartilage and knee synovial fluid, and the contents of interleukin-1β (IL-1β) and IL-6 significantly increased in knee synovial fluid. In addition, rCTRP9 alleviated MIA-induced inflammation, oxidative stress and knee cartilage damage in a dose-dependent way. In addition, rCTRP9 could attenuate the expression of p38MAPK and p-p38 and suppress the expression of nuclear factor-kappa B (NF-κB), p65 and MMPs. Collectively, the results of the present study suggested that CTRP9 alleviates the inflammation of MIA-induced OA through deactivating p38MAPK and NF-κB signaling pathways in rats.

C1q/TNF-Related Protein 9 Inhibits Coxsackievirus B3-Induced Injury in Cardiomyocytes through NF-κB and TGF-β1/Smad2/3 by Modulating THBS1

C1q/TNF-related protein 9 (CTRP9) is implicated in diverse cardiovascular diseases, but its role in viral myocarditis (VMC) is not well explored. This study is aimed at investigating the role and potential mechanism of CTRP9 in VMC. Herein, we found that the peripheral blood collected from children with VMC had lower CTRP9 levels than that from children who had recovered from VMC. H9c2 cardiomyocytes treated with coxsackievirus B3 (CVB3) were applied to establish a VMC model in vitro, and the expression of CTRP9 was significantly decreased in CVB3-induced H9c2 cells. The overexpression of CTRP9 attenuated CVB3-induced apoptosis, inflammation, and fibrosis reactions in H9c2 cells by promoting cell proliferation, reducing the cell apoptosis rate, and inhibiting inflammatory cytokine levels and fibrosis-related gene expression. Moreover, we found that thrombospondin 1 (THBS1) levels were increased in children with VMC, and CTRP9 negatively regulated THBS1 expression by interacting with THBS1. The downregulation of THBS1 inhibited CVB3-induced apoptosis, inflammation, and fibrosis in H9c2 cells. In addition, our mechanistic investigation indicated that the overexpression of THBS1 impaired the inhibitory effect of CTRP9 on CVB3-induced H9c2 cells. The results further revealed that the CVB3-induced NF-κB and TGF-β1/Smad2/3 signaling pathways of H9c2 cells were blocked by CTRP9 yet activated by THBS1. In conclusion, CTRP9 protected H9c2 cells from CVB3-induced injury via the NF-κB and TGF-β1/Smad2/3 signaling pathways by modulating THBS1.

Key Player in Cardiac Hypertrophy, Emphasizing the Role of Toll-Like Receptor 4

Toll-like receptor 4 (TLR4), a key pattern recognition receptor, initiates the innate immune response and leads to chronic and acute inflammation. In the past decades, accumulating evidence has implicated TLR4-mediated inflammatory response in regulation of myocardium hypertrophic remodeling, indicating that regulation of the TLR4 signaling pathway may be an effective strategy for managing cardiac hypertrophy's pathophysiology. Given TLR4's significance, it is imperative to review the molecular mechanisms and roles underlying TLR4 signaling in cardiac hypertrophy. Here, we comprehensively review the current knowledge of TLR4-mediated inflammatory response and its interaction ligands and co-receptors, as well as activation of various intracellular signaling. We also describe the associated roles in promoting immune cell infiltration and inflammatory mediator secretion, that ultimately cause cardiac hypertrophy. Finally, we provide examples of some of the most promising drugs and new technologies that have the potential to attenuate TLR4-mediated inflammatory response and prevent or reverse the ominous cardiac hypertrophy outcomes.

Myeloid differentiation factor 2 in the heart: Bench to bedside evidence for potential clinical benefits?

Cardiac inflammation has been involved in many pathological processes in the heart including cardiac hypertrophy, fibrosis, adverse remodeling, and dysfunction. Myeloid differentiation factor 2 (MD2) is a key mediating protein that has been shown to contribute to the inflammatory process. MD2 is required for the activation of TLR4 in the form of dimerization complex. Upon activation of TLR4, the signal can be sent through either myeloid differentiation primary response protein 88 (Myd88) or toll/interleukin-1 receptor (TIR) domain-containing adaptor inducing IFN-β (TRIF) proteins to activate the inflammatory response in cardiac tissue, after which the inflammatory cytokines and genes are produced. In patients with dilated cardiomyopathy, a positive correlation was demonstrated between the serum MD2 levels and mortality rate. Therefore, MD2 inhibition should provide beneficial effects in inflammation related to cardiac diseases such as obesity and heart failure. Multiple inhibitors of TLR4/MD2 interaction reportedly attenuated cardiac dysfunction and remodeling in animals with obesity and heart failure. In this review, we comprehensively summarized the reports from in vitro, in vivo, and clinical studies regarding the role of MD2 and the effects of MD2 inhibitors on cardiac inflammation, dysfunction, fibrosis, and remodeling. The information regarding the beneficial effects of MD2 inhibitors will be used to encourage future clinical use as a novel anti-inflammatory agent.

CTRP9 induces macrophages polarization into M1 phenotype through activating JNK pathway and enhances VSMCs apoptosis in macrophages and VSMCs co-culture system

Inflammation plays a critical role in the development of atherosclerosis (AS), which has been identified as a major predisposing factor for stroke. Macrophages and VSMCs are associated with plaque formation and progression. Macrophages can dynamically change into two main functional phenotypes, namely M1 and M2, they can produce either pro-inflammatory or anti-inflammatory factors which may affect the outcome of inflammation. As a member of CTRPs family, CTRP9 has been reported play important protective roles in the cardiovascular system. However, whether CTRP9 can regulate macrophage activation status in inflammatory responses and have effect on VSMCs behaviors in co-culture system have not been fully investigated. In the present study, using peritoneal macrophages treated with CTRP9, we found that CTRP9 facilitated macrophages towards M1 phenotype, promoted TNF-α secretion and MMPs expression. CTRP9 showed synergistic effect with LPS in inducing M1 macrophages. In macrophages-VSMCs co-culture system, apoptosis and down-regulated proliferation of VSMCs were accelerated with CTRP9-treated macrophages. Then we attempted to explore the underlying molecular mechanisms of CTRP9 resulting in M1 activation. The c-Jun NH2-terminal kinases (JNK) are members of the mitogen activated protein kinases (MAPK) family, plays a central role in the cell stress response, with outcomes ranging from cell death to cell proliferation and survival. We found JNK expression was upregulated following CTRP9 stimulation, and inhibiting JNK phosphorylation level was associated with decreased expression of M1 markers and TNF-α concentration. Moreover, VSMCs apoptosis were ameliorated after inhibition of JNK. These results suggested that CTRP9 may promote macrophage towards M1 activation status through JNK signaling pathway activation.

Iminostilbene, a novel small-molecule modulator of PKM2, suppresses macrophage inflammation in myocardial ischemia-reperfusion injury

Introduction

Inflammation is a key factor in myocardial ischemia/reperfusion (MI/R) injury. Targeting leucocyte-mediated inflammation is an important strategy for MI/R therapy. Iminostilbene (ISB), a simple dibenzoazepine small molecule compound, has a strong anti-neurodegenerative effect. However, no study has shown the cardioprotective effect of ISB.

Objectives

This study aimed to investigate the role of ISB against MI/R injury and identify its molecular target.

Methods

To verify the cardiac protection of ISB in vivo and in vitro, we performed rat MI/R surgery and subjected inflammatory modeling of macrophages. In terms of molecular mechanisms, we designed and synthesized a small molecular probe of ISB and employed it on the click chemistry-activity-based protein profiling technique to fish for ISB targets in macrophages. To identify the target, we applied the competitive inhibition assay, surface-plasmon resonance (SPR), cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) assay.

Results

In vivo, ISB showed robust anti-myocardial injury activity by improving cardiac function, reducing myocardial infarction, and inhibiting macrophage-mediated inflammation. In vitro, ISB strongly inhibited the transcription and the expression levels of inflammatory cytokines in macrophages. The pyruvate kinase isozyme type M2 (PKM2) was identified as the potential target of ISB through proteomic analysis and the competitive assay was performed for specific binding verification. Further thermodynamic and kinetic experiments showed that ISB was bound to PKM2 in a dose-dependent manner. Moreover, in terms of the biological function of ISB on PKM2, ISB reduced the expression of PKM2, thereby reducing the expression of HIF1α and the phosphorylation of STAT3.

Conclusion

This study for the first time demonstrated that ISB targeted PKM2 to reduce macrophage inflammation thereby significantly alleviating MI/R injury.

Immune checkpoint inhibitor induces cardiac injury through polarizing macrophages via modulating microRNA-34a/Kruppel-like factor 4 signaling

Cancer immunotherapy has become a well-established treatment option for some cancers; however, its use is hampered by its cardiovascular adverse effects. Immune checkpoint inhibitors (ICIs)-related cardiac toxicity took place in kinds of different forms, such as myocarditis, acute coronary syndrome, and pericardial disease, with high mortality rates. This study aimed to investigate the roles of programmed death-1 (PD-1) inhibitor, one of widespread used ICIs, in the development of murine cardiac injury. PD-1 inhibitor is known to transduce immunoregulatory signals that modulate macrophages polarization to attack tumor cells. Hence, this study explored whether the cardiovascular adverse effects of PD-1 inhibitor were related to macrophage polarization. MicroRNA-34a (miR-34a), which appears to regulate the polarization of cultured macrophages to induce inflammation, is examined in cardiac injury and macrophage polarization induced by the PD-1 inhibitor. As a target of miR-34a, Krüppel-like factor 4 (KLF4) acted as an anti-inflammation effector to take cardiac protective effect. Further, it investigated whether modulating the miR-34a/KLF4-signaling pathway could influence macrophage polarization. The PD-1 inhibitor markedly induced M1 phenotype macrophage polarization with impaired cardiac function, whereas miR-34a inhibitor transfection treatment reversed M1 polarization and cardiac injury in vivo. In vitro, PD-1 inhibitor-induced M1 polarization was accompanied by an increase in the expression of miR-34a but a decrease in the expression of KLF4. TargetScan and luciferase assay showed that miR-34a targeted the KLF4 3′-untranslated region. Either miR-34a inhibition or KLF4 overexpression could abolish M1 polarization induced by the PD-1 inhibitor. The findings strongly suggested that the PD-1 inhibitor exerted its effect in promoting M1 polarization and cardiac injury by modulating the miR-34a/KLF4-signaling pathway and inducing myocardial inflammation. These findings might help us to understand the pathogenesis of cardiac injury during immunotherapy, and provide new targets in ameliorating cardiac injury in patients with cancer receiving PD-1 inhibitor treatment.

Therapeutic effects of KANK2 in myocardial infarction rats might be associated with the NF-κB p65 inhibition

OBJECTIVE

KN motif and ankyrin repeat domains 2 (KANK2) may inhibit the activation of (NF-kappaB) p65, which plays a role in myocardial injury. Thus, our study aims to discover the effect of KANK2 on myocardial infarction (MI) induced by ligating the left anterior descending coronary artery (LAD) through regulating NF-κB p65 in vivo.

METHODS

MI rats underwent LAD ligation were administered with intramyocardial injections of KANK2/Control activation plasmids. Six weeks after MI, pressure-volume (P/V) loops was used to investigate the cardiac function of rats, then the following detections were performed, including TTC staining, HE staining, immunofluorescence, Masson' s trichrome staining, ELISA assay, TUNEL staining, immunohistochemistry, qRT-PCR and Western blotting.

RESULTS

MI rats decreased in maximum pressure (p_max), ejection fraction (EF%), peak rate of pressure rise (dpdt_max) and decline (-dpdt_max) with increased end diastolic pressure (EDP), which was partially reversed by KANK2 overexpression. Besides, KANK2 CRISPR activation plasmids reduced infarct size with less collagen fiber proliferation and neutrophil infiltration in infarct tissues, as well as suppressed pro-inflammatory factors expressions in MI rats. Moreover, injection of KANK2 activation plasmid decreased collagen deposition, aggravated cardiomyocyte apoptosis, enhanced the capillary density, and increased the expressions of VEGF and bFGF in the infarct and peri-infarct regions of MI rats. KANK2 lowered myocardial NF-κB p65 expression in MI rats.

CONCLUSION

KANK2 may play its therapeutic role in MI through improving cardiac function, decreasing myocardial collagen deposition, reducing cardiomyocyte apoptosis, and increasing angiogenesis, which might be associated with the reduction of NF-κB p65 expression.

Over-expression of microRNA-145 drives alterations in β-adrenergic signaling and attenuates cardiac remodeling in heart failure post myocardial infarction

Background: Numerous studies have highlighted the crucial role of microRNA-145 (miR-145) in coronary atherosclerosis and myocardial ischemia reperfusion injury. However, effects of miR-145 on β-adrenergic signaling and cardiac remodeling in heart failure (HF) remains unclarified.

Methods and Results: We established HF model in rats with left anterior descending coronary artery (LAD) occlusion. Four weeks after LAD ligation, rats showed substantial aggravation of cardiac dilation and electrophysiological instability. Up-regulation of miR-145 ameliorated HF-induced myocardial fibrosis and prolonged action potential duration. Echocardiography revealed increased basal contractility and decreased left ventricular inner-diameter in miR-145 over-expressed heart, while cardiac response to β-adrenergic receptor (βAR) stimulation was reduced. Furthermore, miR-145 increased L-type calcium current (I_Ca) density while decreased I_Ca response to β-adrenergic stimulation with isoproterenol. The alterations in βAR signaling might be predominant due to miR-145-mediated activation of Akt/CREB cascades. At high frequency pacing, Ca²⁺ transient, cell shortening and frequency of Ca²⁺ waves were significantly improved in AD-miR-145 group. Western blotting revealed that increased expression of Ca_v1.2, Ca²⁺-ATPase, β2AR, GNAI3 and decreased level of CaMKII might be attributed to the cardioprotective effects of miR-145.

Conclusion: miR-145 effectively alleviates HF-related cardiac remodeling by improving cardiac dilation, fibrosis, intracellular Ca²⁺ mishandling and electrophysiological instability.

A murine model of increased coronary sinus pressure induces myocardial edema with cardiac lymphatic dilation and fibrosis

Myocardial edema is a consequence of many cardiovascular stressors, including myocardial infarction, cardiac bypass surgery, and hypertension. The aim of this study was to establish a murine model of myocardial edema and elucidate the response of cardiac lymphatics and the myocardium. Myocardial edema without infarction was induced in mice by cauterizing the coronary sinus, increasing pressure in the coronary venous system, and inducing myocardial edema. In male mice, there was rapid development of edema 3 h following coronary sinus cauterization (CSC), with associated dilation of cardiac lymphatics. By 24 h, males displayed significant cardiovascular contractile dysfunction. In contrast, female mice exhibited a temporal delay in the formation of myocardial edema, with onset of cardiovascular dysfunction by 24 h. Furthermore, myocardial edema induced a ring of fibrosis around the epicardial surface of the left ventricle in both sexes that included fibroblasts, immune cells, and increased lymphatics. Interestingly, the pattern of fibrosis and the cells that make up the fibrotic epicardial ring differ between sexes. We conclude that a novel surgical model of myocardial edema without infarct was established in mice. Cardiac lymphatics compensated by exhibiting both an acute dilatory and chronic growth response. Transient myocardial edema was sufficient to induce a robust epicardial fibrotic and inflammatory response, with distinct sex differences, which underscores the sex-dependent differences that exist in cardiac vascular physiology.NEW & NOTEWORTHY Myocardial edema is a consequence of many cardiovascular stressors, including myocardial infarction, cardiac bypass surgery, and high blood pressure. Cardiac lymphatics regulate interstitial fluid balance and, in a myocardial infarction model, have been shown to be therapeutically targetable by increasing heart function. Cardiac lymphatics have only rarely been studied in a noninfarct setting in the heart, and so we characterized the first murine model of increased coronary sinus pressure to induce myocardial edema, demonstrating distinct sex differences in the response to myocardial edema. The temporal pattern of myocardial edema induction and resolution is different between males and females, underscoring sex-dependent differences in the response to myocardial edema. This model provides an important platform for future research in cardiovascular and lymphatic fields with the potential to develop therapeutic interventions for many common cardiovascular diseases.

Dexmedetomidine Exerted Anti-arrhythmic Effects in Rat With Ischemic Cardiomyopathy via Upregulation of Connexin 43 and Reduction of Fibrosis and Inflammation

Background

Persistent myocardial ischemia post-myocardial infarction can lead to fatal ventricular arrhythmias such as ventricular tachycardia and fibrillation, both of which carry high mortality rates. Dexmedetomidine (Dex) is a highly selective α2-agonist used in surgery for congenital cardiac disease because of its antiarrhythmic properties. Dex has previously been reported to prevent or terminate various arrhythmias. The purpose of the present study was to determine the anti-arrhythmic properties of Dex in the context of ischemic cardiomyopathy (ICM) after myocardial infarction.

Methods and Results

We randomly allocated 48 rats with ICM, created by persistent ligation of the left anterior descending artery for 4 weeks, into six groups: Sham (n = 8), Sham + BML (n = 8), ICM (n = 8), ICM + BML (n = 8), ICM + Dex (n = 8), and ICM + Dex + BML (n = 8). Treatments started after ICM was confirmed (the day after echocardiographic measurement) and continued for 4 weeks (inject intraperitoneally, daily). Dex inhibited the generation of collagens, cytokines, and other inflammatory mediators in rats with ICM via the suppression of NF-κB activation and increased the distribution of connexin 43 (Cx43) via phosphorylation of adenosine 5′-monophosphate-activated protein kinase (AMPK). Dex reduced the occurrence of spontaneous ventricular arrhythmias (ventricular premature beat or ventricular tachycardia), decreased the inducibility quotient of ventricular arrhythmias induced by PES, and partly improved cardiac contraction. The AMPK antagonist BML-275 dihydrochloride (BML) partly weakened the cardioprotective effect of Dex.

Conclusion

Dex conferred anti-arrhythmic effects in the context of ICM via upregulation of Cx43 and suppression of inflammation and fibrosis. The anti-arrhythmic and anti-inflammatory properties of Dex may be mediated by phosphorylation of AMPK and subsequent suppression of NF-κB activation.

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.

Over-Expression of Inhibitor of Differentiation 2 Attenuates Post-Infarct Cardiac Fibrosis Through Inhibition of TGF-β1/Smad3/HIF-1α/IL-11 Signaling Pathway

Background: Cardiac fibrosis after myocardial infarction mainly causes cardiac diastolic and systolic dysfunction, which results in fatal arrhythmias or even sudden death. Id2, a transcriptional repressor, has been shown to play an important role in the development of fibrosis in various organs, but its effects on cardiac fibrosis remain unclear. This study aimed to explore the effects of Id2 on cardiac fibrosis after myocardial infarction and its possible mechanisms.

Methods: This study was performed in four experimental groups: control group, treatment group (including TGF-β1, hypoxia or MI), treatment+GFP group and treatment+Id2 group. In vitro anoxic and fibrotic models were established by subjecting CFs or NRVMs to a three-gas incubator or TGF-β1, respectively. An animal myocardial infarction model was established by ligating of the left anterior descending coronary artery followed by directly injecting of Id2 adenovirus into the myocardial infarct’s marginal zone.

Results: The results showed that Id2 significantly improved cardiac EF and attenuated cardiac hypertrophy. The mRNA and protein levels of α-SMA, Collagen I, Collagen III, MMP2 and TIMP1 were higher in treatment+Id2 group than those in treatment group as well as in treatment+GFP group both in vivo and in vitro. Immunofluorescence revealed that both α-SMA and vimentin were co-expressed in the treatment group and GFP group, but the co-expression were not detected in the control group and Id2 group. Additionally, our findings illustrated that Id2 had protective effects demonstrated by its ability to inhibit the TGF-β1/Smad3/HIF-1α/IL-11 signaling pathways. Besides, over-expression of Id2 reduced cardiomyocytes apoptosis.

Conclusion: In conclusion, this study demonstrated that over-expression of Id2 preserved cardiac function and ameliorated adverse cardiac remodeling, which might be a promising treatment target for cardiac fibrosis and apoptosis.

CTRP9 Ameliorates Atrial Inflammation, Fibrosis, and Vulnerability to Atrial Fibrillation in Post-Myocardial Infarction Rats

Background

Inflammation and fibrosis play an important role in the pathogenesis of atrial fibrillation (AF) after myocardial infarction (MI). CTRP9 (C1q/tumor necrosis factor‐related protein‐9) as a secreted glycoprotein can reverse left ventricle remodeling post‐MI, but its effects on MI‐induced atrial inflammation, fibrosis, and associated AF are unknown.

Methods and Results

MI model rats received adenoviral supplementation of CTRP9 (Ad‐CTRP9) by jugular‐vein injection. Cardiac function, inflammatory, and fibrotic indexes and related signaling pathways, electrophysiological properties, and AF inducibility of atria in vivo and ex vivo were detected in 3 or 7 days after MI. shCTRP9 (short hairpin CTRP9) and shRNA were injected into rat and performed similar detection at day 5 or 10. Adverse atrial inflammation and fibrosis, cardiac dysfunction were induced in both MI and Ad‐GFP (adenovirus‐encoding green fluorescent protein)+MI rats. Systemic CTRP9 treatment improved cardiac dysfunction post‐MI. CTRP9 markedly ameliorated macrophage infiltration and attenuated the inflammatory responses by downregulating interleukin‐1β and interleukin‐6, and upregulating interleukin‐10, in 3 days post‐MI; depressed left atrial fibrosis by decreasing the expressions of collagen types I and III, α‐SMA, and transforming growth factor β1 in 7 days post‐MI possibly through depressing the Toll‐like receptor 4/nuclear factor‐κB and Smad2/3 signaling pathways. Electrophysiologic recordings showed that increased AF inducibility and duration, and prolongation of interatrial conduction time induced by MI were attenuated by CTRP9; moreover, CTRP9 was negatively correlated with interleukin‐1β and AF duration. Downregulation of CTRP9 aggravated atrial inflammation, fibrosis, susceptibility of AF and prolonged interatrial conduction time, without affecting cardiac function.

Conclusions

CTRP9 is effective at attenuating atrial inflammation and fibrosis, possibly via its inhibitory effects on the Toll‐like receptor 4/nuclear factor‐κB and Smad2/3 signaling pathways, and may be an original upstream therapy for AF in early phase of MI.

C1q/TNF-related protein-9 promotes macrophage polarization and improves cardiac dysfunction after myocardial infarction

The timely regulation of inflammatory M1 macrophage polarization toward regenerative M2 macrophages suggests the possibility of immunotherapy after myocardial infarction (MI). C1q/TNF‐related protein‐9 (CTRP9) has anti‐inflammatory effects and can ameliorate heart function in mice after long‐term myocardial infarction. The role of CTRP9 in macrophage polarization remains completely unclear. This study determined whether CTRP9 can preserve post‐MI early cardiac function through the regulation of macrophage polarization. In the present study, an adenovirus‐delivered CTRP9 supplement promoted macrophage polarization at Day 3 post MI and improved cardiac function at Day 7 post MI. Pretreatment with gCTRP9 promoted the M1 to M2 polarization transition and attenuated inflammation after lipopolysaccharide + interferon‐γ stimulation; the effects were partly abrogated by the adenosine monophosphate kinase (AMPK) inhibitor compound C and were obviously reinforced by pyrrolidine dithiocarbamate, a nuclear factor‐κB (NF‐κB) inhibitor. Meanwhile, CTPR9 markedly reduced the expression of toll‐like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and NF‐κB p65 phosphorylation by promoting AMPK phosphorylation in vivo and in vitro. Moreover, the competitive binding of gCTRP9 and LPS to the myeloid differentiation protein 2 (MD2)/TLR4 complex was associated with direct binding to MD2, thereby inhibiting the downstream signaling molecule MyD88. Taken together, we demonstrated that CTRP9 improved post‐MI early cardiac function, at least in part, by modulating M1/M2 macrophage polarization, largely via the TLR4/MD2/MyD88 and AMPK‐NF‐κB pathways.