CTRP9 protein protects against myocardial injury following ischemia-reperfusion through AMP-activated protein kinase (AMPK)-dependent mechanism

Loss of CTRP10 results in female obesity with preserved metabolic health

Obesity is a major risk factor for type 2 diabetes, dyslipidemia, cardiovascular disease, and hypertension. Intriguingly, there is a subset of metabolically healthy obese (MHO) individuals who are seemingly able to maintain a healthy metabolic profile free of metabolic syndrome. The molecular underpinnings of MHO, however, are not well understood. Here, we report that CTRP10/C1QL2-deficient mice represent a unique female model of MHO. CTRP10 modulates weight gain in a striking and sexually dimorphic manner. Female, but not male, mice lacking CTRP10 develop obesity with age on a low-fat diet while maintaining an otherwise healthy metabolic profile. When fed an obesogenic diet, female Ctrp10 knockout (KO) mice show rapid weight gain. Despite pronounced obesity, Ctrp10 KO female mice do not develop steatosis, dyslipidemia, glucose intolerance, insulin resistance, oxidative stress, or low-grade inflammation. Obesity is largely uncoupled from metabolic dysregulation in female KO mice. Multi-tissue transcriptomic analyses highlighted gene expression changes and pathways associated with insulin-sensitive obesity. Transcriptional correlation of the differentially expressed gene (DEG) orthologs in humans also shows sex differences in gene connectivity within and across metabolic tissues, underscoring the conserved sex-dependent function of CTRP10. Collectively, our findings suggest that CTRP10 negatively regulates body weight in females, and that loss of CTRP10 results in benign obesity with largely preserved insulin sensitivity and metabolic health. This female MHO mouse model is valuable for understanding sex-biased mechanisms that uncouple obesity from metabolic dysfunction.

Loss of CTRP10 results in female obesity with preserved metabolic health

Obesity is a major risk factor for type 2 diabetes, dyslipidemia, cardiovascular disease, and hypertension. Intriguingly, there is a subset of metabolically healthy obese (MHO) individuals who are seemingly able to maintain a healthy metabolic profile free of metabolic syndrome. The molecular underpinnings of MHO, however, are not well understood. Here, we report that CTRP10/C1QL2-deficient mice represent a unique female model of MHO. CTRP10 modulates weight gain in a striking and sexually dimorphic manner. Female, but not male, mice lacking CTRP10 develop obesity with age on a low-fat diet while maintaining an otherwise healthy metabolic profile. When fed an obesogenic diet, female Ctrp10 knockout (KO) mice show rapid weight gain. Despite pronounced obesity, Ctrp10 KO female mice do not develop steatosis, dyslipidemia, glucose intolerance, insulin resistance, oxidative stress, or low-grade inflammation. Obesity is largely uncoupled from metabolic dysregulation in female KO mice. Multi-tissue transcriptomic analyses highlighted gene expression changes and pathways associated with insulin-sensitive obesity. Transcriptional correlation of the differentially expressed gene (DEG) orthologous in humans also shows sex differences in gene connectivity within and across metabolic tissues, underscoring the conserved sex-dependent function of CTRP10. Collectively, our findings suggest that CTRP10 negatively regulates body weight in females, and that loss of CTRP10 results in benign obesity with largely preserved insulin sensitivity and metabolic health. This female MHO mouse model is valuable for understanding sex-biased mechanisms that uncouple obesity from metabolic dysfunction.

Association between circulating CTRP9 levels and coronary artery disease: a systematic review and meta-analysis

Background

C1q tumor necrosis factor (TNF) related proteins 9 (CTRP9) is a novel adipocytokine that has been shown to have a cardioprotective effect in coronary artery disease (CAD). However, there are conflicting results on circulating levels of CTRP9 in patients with and without CAD. This meta-analysis was conducted to investigate the association between circulating CTRP9 levels and CAD.

Objective

The aim of this meta-analysis was to re-examine the relationship between circulating CTRP9 levels and CAD.

Methods

We searched PubMed, Web of Science, Embase, Cochrane Library, CNKI, VIP, Wanfang Data, and CBM for relevant studies up to October 2023, and 193 articles were identified. After reading the title, abstract and full text, a total of 25 articles were included in this meta-analysis. A prespecified protocol registered at INPLASY was followed (INPLASY202450066). Due to the high heterogeneity, we performed subgroup analyses and meta-regression based on patient characteristics, complications, clinical biochemical indicators, coronary artery lesion, and CAD classification. Publication bias was assessed using Egger's linear regression tests, Begg's rank correlation tests, and funnel plots.

Results

The results showed that the patient with CAD had significantly lower circulating CTRP9 levels than the control group (Z = 3.26, P = 0.001). Subgroup analysis and meta-regression findings demonstrated that observed heterogeneity could be attributed to population distribution. Patient characteristics (year of publication, patients' age, and BMI), complications (diabetes and type 2 diabetes mellitus (T2DM)), clinical biochemical indicators, coronary artery lesion (stability of coronary atherosclerotic plaque, and the number of diseased coronary vessels), and classification of CAD were not identified as source of heterogeneity.

Conclusions

The meta-analysis confirmed that circulating CTRP9 levels in CAD patients are significantly lower than those in patients without CAD. The association may be modified by the population distribution.

CTRP9: An Anti-Atherosclerotic Factor in ApoE Knockout Mice through Oxidative Stress Inhibition

BACKGROUND

C1q/tumor necrosis factor-related protein-9 (CTRP9) is critically involved in the pathophysiology of metabolic and cardiovascular disorders. This investigation aimed to clarify the mechanism underlying the role of CTRP9 in atherosclerosis in apolipoprotein E (ApoE) knockout (KO) mice.

METHODS

ApoE KO mice were fed a Western diet and injected with a virus which resulted in CTRP9 overexpression or knockdown for 12 weeks. The plasma lipid levels and atherosclerotic plaque areas were measured after the mice were euthanized. Aortas were isolated, and RNA sequencing was performed to identify the differentially expressed genes and related signaling pathways. Finally, plasma oxidative stress factors were measured to demonstrate the reliability of the RNA sequencing results.

RESULTS

The plasma lipid levels in the CTRP9 overexpression group did not significantly differ from those in the green fluorescence protein (GFP) group. Markablely, CTRP9 overexpression inhibited atherosclerotic plaque formation in ApoE KO mice, whereas CTRP9 knockdown promoted plaque formation. RNA sequencing analysis identified 3485 differentially expressed genes that were prominently enriched across 55 signaling pathways. Additionally, plasma oxidative stress factors were significantly reduced after CTRP9 overexpression, whereas these factors were increased after CTRP9 knockdown, which was consistent with the results of the RNA sequencing analysis.

CONCLUSIONS

These findings demonstrated that CTRP9 alleviated inflammation and cholesterol metabolism, which reduced oxidative stress in an atherosclerotic animal model. These beneficial effects may mediate the suppression of lesion development in the aorta.

Advances in bi-directional relationships for EZH2 and oxidative stress

Over the past two decades, polycomb repressive complex 2(PRC2) has emerged as a vital repressive complex in overall cell fate determination. In mammals, enhancer of zeste homolog 2 (EHZ2), which is the core component of PRC2, has also been recognized as an important regulator of inflammatory, redox, tumorigenesis and damage repair signalling networks. To exert these effects, EZH2 must regulate target genes epigenetically or interact directly with other gene expression-regulating factors, such as LncRNAs and microRNAs. Our review provides a comprehensive summary of research advances, discoveries and trends regarding the regulatory mechanisms between EZH2 and reactive oxygen species (ROS). First, we outline novel findings about how EZH2 regulates the generation of ROS at the molecular level. Then, we summarize how oxidative stress controls EHZ2 alteration (upregulation, downregulation, or phosphorylation) via various molecules and signalling pathways. Finally, we address why EZH2 and oxidative stress have an undefined relationship and provide potential future research ideas.

CTRP13 ablation improves systemic glucose and lipid metabolism

OBJECTIVE

Tissue crosstalk mediated by secreted hormones underlies the integrative control of metabolism. We previously showed that CTRP13/C1QL3, a secreted protein of the C1q family, can improve glucose metabolism and insulin action in vitro and reduce food intake and body weight in mice when centrally delivered. A role for CTRP13 in regulating insulin secretion in isolated islets has also been demonstrated. It remains unclear, however, whether the effects of CTRP13 on cultured cells and in mice reflect the physiological function of the protein. Here, we use a loss-of-function mouse model to address whether CTRP13 is required for metabolic homeostasis.

METHODS

WT and Ctrp13 knockout (KO) mice fed a standard chow or a high-fat diet were subjected to comprehensive metabolic phenotyping. Transcriptomic analyses were carried out on visceral and subcutaneous fat, liver, and skeletal muscle to identify pathways altered by CTRP13 deficiency. RNA-seq data was further integrated with the Metabolic Syndrome in Man (METSIM) cohort data. Adjusted regression analysis was used to demonstrate that genetic variation of CTRP13 expression accounts for a significant proportion of variance between differentially expressed genes (DEGs) in adipose tissue and metabolic traits in humans.

RESULTS

Contrary to expectation, chow-fed Ctrp13-KO male mice had elevated physical activity, lower body weight, and improved lipid handling. On a high-fat diet (HFD), Ctrp13-KO mice of either sex were consistently more active and leaner. Loss of CTRP13 reduced hepatic glucose output and improved glucose tolerance, insulin sensitivity, and triglyceride clearance, though with notable sex differences. Consistent with the lean phenotype, transcriptomic analyses revealed a lower inflammatory profile in visceral fat and liver. Reduced hepatic steatosis was correlated with the suppression of lipid synthesis and enhanced lipid catabolism gene expression. Visceral fat had the largest number of DEGs and mediation analyses on the human orthologs of the DEGs suggested the potential causal contribution of CTRP13 to human metabolic syndrome.

CONCLUSIONS

Our results suggest that CTRP13 is a negative metabolic regulator, and its deficiency improves systemic metabolic profiles. Our data also suggest the reduction in circulating human CTRP13 levels seen in obesity and diabetes may reflect a compensatory physiologic response to counteract insulin resistance.

CTRP9 alleviates hypoxia/reoxygenation-induced human placental vascular endothelial cells impairment and mitochondrial dysfunction through activating AMPK/Nrf2 signaling

BACKGROUND

Pregnancy-induced hypertension (PIH) is associated with significant maternal and fetal mortality. The present study is aimed at exploring the molecular mechanism of C1q/TNF-related protein 9 (CTRP9) in PIH.

METHODS

Human placental vascular endothelial cells (HPVECs) underwent hypoxia/reoxygenation (H/R) to construct an in vitro PIH cellular model. Cell transfection was conducted to over-express CTRP9. The expression level of CTRP9 was determined by western blot and quantitative real-time PCR. CCK-8, flow cytometry, wound-healing and tube formation assays were conducted to assess cell viability, apoptosis, migration and angiogenesis, respectively. Mitochondrial membrane potential (∆ψm) was evaluated adopting JC-1 staining. Mitochondrial ROS and copy number (mtDNA) were examined using superoxide indicator and real-time PCR, respectively. Then, HPVECs were pre-treated with Compound C (CC), the inhibitor of AMPK, for regulatory mechanism research.

RESULTS

CTRP9 was downregulated in HPVECs exposed to H/R induction. CTRP9 overexpression retards H/R-mediated cell viability loss and apoptosis, impaired migration and angiogenesis of HPVECs. Meanwhile, CTRP9 overexpression alleviates H/R-mediated mitochondrial dysfunction in HPVECs by enhancing mitochondrial ∆ψm, reducing mitochondrial ROS generation and increasing mtDNA copies. In addition, CTRP9 activated AMPK/Nrf2 signaling in H/R-mediated HPVECs, and additional treatment of CC greatly weakened the functional effects of CTRP9 in H/R-mediated HPVECs.

CONCLUSION

Our results suggested that CTRP9 protected against H/R-mediated HPVECs injuries dependent on AMPK/Nrf2 signaling and could be applied as a potential therapy for PIH.

Herbal medicine for the treatment of obesity-associated asthma: a comprehensive review

Obesity is fast growing as a global pandemic and is associated with numerous comorbidities like cardiovascular disease, hypertension, diabetes, gastroesophageal reflux disease, sleep disorders, nephropathy, neuropathy, as well as asthma. Studies stated that obese asthmatic subjects suffer from an increased risk of asthma, and encounter severe symptoms due to a number of pathophysiology. It is very vital to understand the copious relationship between obesity and asthma, however, a clear and pinpoint pathogenesis underlying the association between obesity and asthma is scarce. There is a plethora of obesity-asthma etiologies reported viz., increased circulating pro-inflammatory adipokines like leptin, resistin, and decreased anti-inflammatory adipokines like adiponectin, depletion of ROS controller Nrf2/HO-1 axis, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) associated macrophage polarization, hypertrophy of WAT, activation of Notch signaling pathway, and dysregulated melanocortin pathway reported, however, there is a very limited number of reports that interrelates these pathophysiologies. Due to the underlying complex pathophysiologies exaggerated by obese conditions, obese asthmatics respond poorly to anti-asthmatic drugs. The poor response towards anti-asthmatic drugs may be due to the anti-asthmatics approach only that ignores the anti-obesity target. So, aiming only at the conventional anti-asthmatic targets in obese-asthmatics may prove to be futile until and unless treatment is directed towards ameliorating obesity pathogenesis for a holistic approach towards amelioration of obesity-associated asthma. Herbal medicines for obesity as well as obesity-associated comorbidities are fast becoming safer and more effective alternatives to conventional drugs due to their multitargeted approach with fewer adverse effects. Although, herbal medicines are widely used for obesity-associated comorbidities, however, a limited number of herbal medicines have been scientifically validated and reported against obesity-associated asthma. Notable among them are quercetin, curcumin, geraniol, resveratrol, β-Caryophyllene, celastrol, tomatidine to name a few. In view of this, there is a dire need for a comprehensive review that may summarize the role of bioactive phytoconstituents from different sources like plants, marine as well as essential oils in terms of their therapeutic mechanisms. So, this review aims to critically discuss the therapeutic role of herbal medicine in the form of bioactive phytoconstituents against obesity-associated asthma available in the scientific literature to date.

C1q/tumor necrosis factor-related protein-9 exerts antioxidant and anti-inflammatory effects on oxygen-glucose deprivation/reoxygenation-stimulated neurons by modulating the Akt-GSK-3β-Nrf2 cascade via AdipoR1

C1q/tumor necrosis factor-related protein-9 (CTRP9) is linked to diverse pathological conditions via the effects on cell apoptosis, inflammatory response, and oxidative stress. However, its functional relevance in ischemic brain injury is not well determined. The present work aimed to evaluate the role of CTRP9 in ischemia/reperfusion-associated neuronal injury using an in vitro model. The cultured cortical neurons were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate ischemia/reperfusion in vitro. CTRP9 level was lowered in cultured neurons exposed to OGD/R. Neurons with overexpressed CTRP9 were resistant to OGD/R-elicited injuries, including neuronal apoptosis, oxidative stress, and pro-inflammatory response. Mechanism research revealed that CTRP9 could boost the activation of the nuclear factor erythroid 2-related factor (Nrf2) pathway associated with modulation of the Akt-glycogen synthase kinase-3β (GSK-3β) axis. CTRP9 regulated the transduction of the Akt-GSK-3β-Nrf2 cascade via adiponectin receptor 1 (AdipoR1). Restraining Nrf2 could diminish CTRP9-mediated neuroprotective effects in OGD/R-injured neurons. Altogether, these results confirmed that CTRP9 exerts a protective effect on OGD/R-injured neurons by modulating Akt-GSK-3β-Nrf2 cascade via AdipoR1. This work suggests a possible link between CTRP9 and ischemic brain injury.

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.

7.0T cardiac magnetic resonance imaging of right ventricular function in rats with high-altitude deacclimatization

Background

High-altitude deacclimatization syndrome (HADAS) is a severe public health issue. The study of the changes in right ventricular function caused by high-altitude deacclimatization (HADA) is of great significance for the prevention and treatment of HADAS.

Methods

Six-week-old, male Sprague Dawley (SD) rats were randomly divided into the plain, plateau and the HADA group. Rats in the plateau and plain group were exposed to altitudes of 3,850 and 360 m, respectively, for 12 weeks. Rats in HADA group were exposed to the plateau altitude of 3,850 m for 12 weeks and subsequently transported to the plain altitude of 360 m for 4 weeks. Right ventricular ejection fraction (RVEF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and myocardial strain parameters, including the global longitudinal strain (GLS), global radial strain (GRS), and global circumferential strain (GCS), were evaluated by 7.0T cardiac magnetic resonance (CMR). The levels of red blood cell (RBC), hemoglobin (HGB), and hematocrit (HCT) in the blood were measured, and hematoxylin-eosin (HE) staining was used to observe the pathological changes in the myocardium.

Results

In rats in the plateau group, the right ventricular fibrous space was slightly widened, and partial focal steatosis were observed. However, in the HADA group, only a few focal steatoses were found. Rats in the plateau group had elevated levels of RBC, HGB and HCT, increased right ventricular end-diastolic volume (RVEDV), right ventricular end-systolic volume (RVESV) and right ventricular stroke volume (RVSV), and decreased right ventricular global longitudinal strain (RVGLS), right ventricular global circumferential strain (RVGCS), and right ventricular global radial strain (RVGRS) compared to rats in the plain group (P<0.001). The RVEDV, RVGCS, and RVGRS in the HADA group basically returned to the plain state. Interestingly, the RVESV in the HADA group was higher, while the RVSV, RVEF, and RVGLS were lower than those in the other two groups.

Conclusions

After 12 weeks of exposure to high-altitude environment, there were some pathological changes and the whole contractile strain of the right ventricle was observed. Some pathological changes in the myocardial tissue and stroma recovered after returning to the plain for 4 weeks. However, the right ventricular systolic function and strain did not recover completely.

C1q and Tumor Necrosis Factor Related Protein 9 Protects from Diabetic Cardiomyopathy by Alleviating Cardiac Insulin Resistance and Inflammation

(1) Background: Diabetic cardiomyopathy is a major health problem worldwide. CTRP9, a secreted glycoprotein, is mainly expressed in cardiac endothelial cells and becomes downregulated in mouse models of diabetes mellitus; (2) Methods: In this study, we investigated the impact of CTRP9 on early stages of diabetic cardiomyopathy induced by 12 weeks of high-fat diet; (3) Results: While the lack of CTRP9 in knock-out mice aggravated insulin resistance and triggered diastolic left ventricular dysfunction, AAV9-mediated cardiac CTRP9 overexpression ameliorated cardiomyopathy under these conditions. At this early disease state upon high-fat diet, no fibrosis, no oxidative damage and no lipid deposition were identified in the myocardium of any of the experimental groups. Mechanistically, we found that CTRP9 is required for insulin-dependent signaling, cardiac glucose uptake in vivo and oxidative energy production in cardiomyocytes. Extensive RNA sequencing from myocardial tissue of CTRP9-overexpressing and knock-out as well as respective control mice revealed that CTRP9 acts as an anti-inflammatory mediator in the myocardium. Hence, CTRP9 knock-out exerted more, while CTRP9-overexpressing mice showed less leukocytes accumulation in the heart during high-fat diet; (4) Conclusions: In summary, endothelial-derived CTRP9 plays a prominent paracrine role to protect against diabetic cardiomyopathy and might constitute a therapeutic target.

Progranulin (PGRN) as a regulator of inflammation and a critical factor in the immunopathogenesis of cardiovascular diseases

Immune dysregulation has been identified as a critical cause of the most common types of cardiovascular diseases (CVDs). Notably, the innate and adaptive immune responses under physiological conditions are typically regulated with high sensitivity to avoid the exacerbation of inflammation, but any dysregulation can probably be associated with CVDs. In this respect, progranulin (PGRN) serves as one of the main components of the regulation of inflammatory processes, which significantly contributes to the immunopathogenesis of such disorders. PGRN has been introduced among the secreted growth factors as one related to wound healing, inflammation, and human embryonic development, as well as a wide variety of autoimmune diseases. The relationship between the serum PGRN and TNF-α ratio with the spontaneous bacterial peritonitis constitute one of the independent predictors of these conditions. The full-length PGRN can thus effectively reduce the calcification of valve interstitial cells, and the granulin precursor (GRN), among the degradation products of PGRN, can be beneficial. Moreover, it was observed that, PGRN protects the heart against ischemia-reperfusion injury. Above all, PGRN also provides protection in the initial phase following myocardial ischemia-reperfusion injury. The protective impact of PGRN on this may be associated with the early activation of the PI3K/Akt signaling pathway. PGRN also acts as a protective factor in hyperhomocysteinemia, probably by down-regulating the wingless-related integration site Wnt/β-catenin signaling pathway. Many studies have further demonstrated that SARS-CoV-2 (COVID-19) has dramatically increased the risks of CVDs due to inflammation, so PGRN has drawn much more attention among scholars. Lysosomes play a pivotal role in the inflammation process, and PGRN is one of the key regulators in their functioning, which contributes to the immunomodulatory mechanism in the pathogenesis of CVDs. Therefore, investigation of PGRN actions can help find new prospects in the treatment of CVDs. This review aims to summarize the role of PGRN in the immunopathogenesis of CVD, with an emphasis on its treatment.

Increased Levels of ANGPTL3 and CTRP9 in Patients With Obstructive Sleep Apnea and Their Relation to Insulin Resistance and Lipid Metabolism and Markers of Endothelial Dysfunction

OBJECTIVE

Obstructive sleep apnea (OSA) has a close relation with obesity and perturbation in adipokines and hepatokines, which are linked to OSA consequences such as insulin resistance, dyslipidemia, and endothelial dysfunction. This study aimed to assess the relation of C1q/TNF-related protein 9 (CTRP9) and angiopoietin-like protein 3 (ANGPTL3) with OSA and biochemical measurements.

METHODS

Serum levels of ANGPTL3, CTRP9, adiponectin, leptin, intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion protein 1 (VCAM-1) were determined in 74 OSA patients and 27 controls using enzyme-linked immunosorbent assay kits.

RESULTS

Levels of ANGPTL3, CTRP9, leptin, ICAM-1, and VCAM-1 were increased in the patients compared to the controls, whereas adiponectin levels decreased. ANGPTL3 had a positive correlation with total cholesterol, triglyceride, low-density lipoprotein cholesterol, ICAM-1, and VCAM-1 and was inversely correlated with leptin. CTRP9 showed a positive correlation with body mass index, insulin resistance, ICAM-1, and VCAM-1.

CONCLUSION

The results indicated the relation of ANGLTP3 and CTRP9 with OSA and its complications, which suggested a possible role for these factors in the consequences of OSA.

Angiogenic adipokine C1q-TNF-related protein 9 ameliorates myocardial infarction via histone deacetylase 7-mediated MEF2 activation

C1q/tumor necrosis factor-related protein 9 (CTRP9) is an adipokine and has high potential as a therapeutic target. However, the role of CTRP9 in cardiovascular disease pathogenesis remains unclear. We found CTRP9 to induce HDAC7 and p38 MAPK phosphorylation via tight regulation of AMPK in vascular endothelial cells, leading to angiogenesis through increased MEF2 activity. The expression of CTRP9 and atheroprotective MEF2 was decreased in plaque tissue of atherosclerotic patients and the ventricle of post-infarction mice. CTRP9 treatment inhibited the formation of atherosclerotic plaques in ApoE KO and CTRP9 KO mice. In addition, CTRP9 induced significant ischemic injury prevention in the post-MI mice. Clinically, serum CTRP9 levels were reduced in patients with MI compared with healthy controls. In summary, CTRP9 induces a vasoprotective response via the AMPK/HDAC7/p38 MAPK pathway in vascular endothelial cells, whereas its absence can contribute to atherosclerosis and MI. Hence, CTRP9 may represent a valuable therapeutic target and biomarker in cardiovascular diseases.

Adiponectin protects skeletal muscle from ischaemia–reperfusion injury in mice through miR ‐21/ PI3K /Akt signalling pathway

Previous studies have confirmed that adiponectin (APN) plays a protective role in myocardial ischaemia-reperfusion (IR) injury, and the aim of this study was to investigate its effect on skeletal muscle. ELISA was used to detect the levels of Creatinine Kinase (CK), LDH, SOD and MDA in the plasma of the lower limbs of mice, and the levels of IL-6, IL-1β and TNF-α in the gastrocnemius. Quantitative PCR was used to detect the expression level of miR-21. TUNEL staining was used to detect the apoptosis of the gastrocnemius. The expression levels of apoptosis proteins, autophagy marker proteins and downstream target genes of miR-21 in gastrocnemius were detected by Western Blot. The results of this study revealed that APN levels were significantly reduced in gastrocnemius of IR mice. The oxidative stress, inflammatory response, apoptosis and autophagy induced by IR were significantly ameliorated by APN injection. The above effects of APN may be achieved through miR-21/PI3K signalling pathway, as found by interfering gene expression levels with miRNA antagomir and lentiviral injection. Taken together, our study revealed that APN protects skeletal muscle from IR injury through miR-21 /PI3K/Akt signalling pathway through inhibiting inflammatory response, apoptosis and autophagy.

Adiponectin System (Rescue Hormone): The Missing Link between Metabolic and Cardiovascular Diseases

The adipose tissue, regardless of its role in generating and storing energy, acts as a key player as an endocrine tissue, producing a wide scale of cytokines/hormones called adipokines. Adipokines such as leptin, resistin, visfatin and osteopontin own pro-inflammatory effects on the cardiovascular system in some cases. In contrast, some adipokines have cardioprotective and anti-inflammatory impacts including adiponectin, omentin, and apelin. One of the key adipokines is adiponectin, the abundant peptide regulating hormone that is released mainly by adipocytes and cardiomyocytes as well as by endothelial and skeletal cells. It acts through two main receptors: AdipoR1 and AdipoR2, forming the "Adiponectin system" which effectively exerts its cellular mechanisms and responses in target cells. It regulates various metabolic processes, while adiponectin is the adipocyte hormone known for its cardioprotective impact in clinical and experimental research. It is also a well-effector metabolic adipokine, since weight loss or diet restriction show a link with rises in adiponectin concentrations, which is accompanied with increasing insulin sensitivity, glucose, and lipids-regulation via adiponectin's antioxidant, anti-inflammatory, anti-fibrotic actions. The high adiponectin level made it an attractive player in developing therapeutical treatments for metabolic syndromes and cardiovascular disease. The elevated plasma levels of adiponectin are mostly attributed to its benefits on cardio-metabolism. In some cases, adiponectin has been paradoxically accompanied with elevated risk of cardiovascular disease, so higher adiponectin concentration is a marker of poor prediction. Thus, the adiponectin system is attractive to researchers as a biomarker of heart disease advancement and a predictor of prognosis during the term of some cardiovascular diseases and its mechanical functions in Hypertension and diabetic patients. This review highlights the physiological roles of adiponectin as an anti-inflammatory and cardioprotective hormone as well as how it plays as a biomarker and potential therapeutic tool in the cardiovascular system in adult, children, and adolescents. The adiponectin system may be seen as a rescue hormone aiding in remodeling of the cardiovascular system on both cellular and molecular levels. The paradox role of adiponectin relevant to cardiovascular mortality should be taken into consideration.

CTRP9 overexpression attenuates palmitic acid‑induced inflammation, apoptosis and impaired migration in HTR8/SVneo cells through AMPK/SREBP1c signaling

Obesity in pregnant mothers often leads to a range of obstetric complications, including miscarriage, pre-eclampsia, gestational hypertension and diabetes. C1q/TNF-related protein 9 (CTRP9) is an adipokine with an anti-inflammatory effect. The aim of the present study was to identify the role of CTRP9 in the pathogenesis of maternal obesity during pregnancy. Following treatment with palmitic acid (PA), HTR8/SVneo cell viability and CTRP9 expression were analyzed using Cell Counting Kit-8 (CCK-8), reverse transcription-quantitative PCR (RT-qPCR) and western blot analyses. The effects of CTRP9 overexpression on cell viability, apoptosis, pro-inflammatory cytokine levels and migration were assessed using CCK-8, TUNEL, RT-qPCR and Transwell assays, respectively. Subsequently, sterol-regulatory element binding protein 1c (SREBP1c) overexpression efficiency was verified using RT-qPCR, and its effects on cell viability, apoptosis, pro-inflammatory cytokines and migration damage were then examined in HTR8/SVneo cells. The results showed that CTRP9 overexpression attenuated the inhibition of cell viability and apoptosis caused by PA in HTR8/SVneo cells, reduced pro-inflammatory cytokine release, improved cell migration and regulated the protein expression level of AMP-activated protein kinase (AMPK)/SREBP1c signaling. In addition, CTRP9 inhibited SREBP1c expression through AMPK signaling, thereby attenuating the inflammation, apoptosis and inhibited migration caused by PA in HTR8/SVneo cells. In brief, CTRP9 protected against inflammation, apoptosis and migration defects in HTR8/SVneo cells exposed to PA treatment through AMPK/SREBP1c signaling, which suggested the potential role of CTRP9 in alleviating the toxicity of PA.

CTRP11 contributes modestly to systemic metabolism and energy balance

C1q/TNF‐related proteins (CTRP1‐15) constitute a conserved group of secreted proteins of the C1q family with diverse functions. In vitro studies have shown that CTRP11/C1QL4 can inhibit adipogenesis, antagonize myoblast fusion, and promote testosterone synthesis and secretion. Whether CTRP11 is required for these processes in vivo remains unknown. Here, we show that knockout (KO) mice lacking CTRP11 have normal skeletal muscle mass and function, and testosterone level, suggesting that CTRP11 is dispensable for skeletal muscle development and testosterone production. We focused our analysis on whether this nutrient‐responsive secreted protein plays a role in controlling sugar and fat metabolism. At baseline when mice are fed a standard chow, CTRP11 deficiency affects metabolic parameters in a sexually dimorphic manner. Only Ctrp11‐KO female mice have significantly higher fasting serum ketones and reduced physical activity. In the refeeding phase following food withdrawal, Ctrp11‐KO female mice have reduced food intake and increased metabolic rate and energy expenditure, highlighting CTRP11’s role in fasting–refeeding response. When challenged with a high‐fat diet to induce obesity and metabolic dysfunction, CTRP11 deficiency modestly exacerbates obesity‐induced glucose intolerance, with more pronounced effects seen in Ctrp11‐KO male mice. Switching to a low‐fat diet after obesity induction results in greater fat loss in wild type relative to KO male mice, suggesting impaired response to obesity reversal and reduced metabolic flexibility in the absence of CTRP11. Collectively, our data provide genetic evidence for novel sex‐dependent metabolic regulation by CTRP11, but note the overall modest contribution of CTRP11 to systemic energy homeostasis.

Putative therapeutic impacts of cardiac CTRP9 in ischaemia/reperfusion injury

Recently, cytokines belonging to C1q/tumour necrosis factor‐related proteins (CTRPs) superfamily have attracted increasing attention due to multiple metabolic functions and desirable anti‐inflammatory effects. These various molecular effectors exhibit key roles upon the onset of cardiovascular diseases, making them novel adipo/cardiokines. This review article aimed to highlight recent findings correlated with therapeutic effects and additional mechanisms specific to the CTRP9, particularly in cardiac ischaemia/reperfusion injury (IRI). Besides, the network of the CTPR9 signalling pathway and its possible relationship with IRI were discussed. Together, the discovery of all involved underlying mechanisms could shed light to alleviate the pathological sequelae after the occurrence of IRI.

Towards harnessing the value of organokine crosstalk to predict the risk for cardiovascular disease in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Importantly, NAFLD increases the risk for cardiovascular disease (CVD). A causal relationship has been substantiated. Given the pandemic proportions of NAFLD, a reliable scoring system for predicting the risk of NAFLD-associated CVD is an urgent medical need. We here review cumulative evidence suggesting that systemically released organokines - especially certain adipokines, hepatokines, and cardiokines - may serve this purpose. The underlying rationale is that these signalers directly communicate between white adipose tissue, liver, and heart as key players in the pathogenesis of NAFLD and resultant CVD events. Moreover, evidence suggests that these organ-specific cytokines are secreted in a biologically predetermined, cascade-like pattern. Consequently, upon pinpointing organokines of relevance, we sketch requirements to establish an algorithm predictive of the CVD risk in patients with NAFLD. Such an algorithm, as to be consolidated in the form of an applicable equation, may be improved continuously by machine learning. To the best of our knowledge, such an option has not yet been considered. Establishing and implementing a reliable algorithm for determining the NAFLD-associated CVD risk has the potential to save many NAFLD patients from life-threatening CVD events.

C1q/tumor necrosis factor-related protein 9 protects cultured chondrocytes from IL-1β-induced inflammatory injury by inhibiting NLRP3 inflammasome activation via the AdipoR1/AMPK axis

C1q/tumor necrosis factor-related protein 9 (CTRP9) has been identified as a novel anti-inflammatory factor that participates in numerous pathological conditions. However, whether CTRP9 participates in the regulation of osteoarthritis has not been studied. This work sought to determine the possible role of CTRP9 in osteoarthritis using an in vitro model, namely interleukin-1β (IL-1β)-stimulated chondrocytes. There was a decreased level of CTRP9 in chondrocytes after IL-1β stimulation. CTRP9 upregulation dramatically repressed IL-1β-evoked apoptosis and inflammatory response in cultured chondrocytes. The mechanistic investigation revealed that CTRP9 overexpression restrained the activation of the nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome in IL-1β-stimulated chondrocytes via the adiponectin receptor 1 (AdipoR1)/adenosine monophosphate-activated protein kinase (AMPK) axis. Notably, inhibition of AdipoR1 or AMPK abolished the regulatory effects of CTRP9 overexpression on IL-1β-evoked apoptosis and inflammasome activation. Overall, the results of this work delineate that CTRP9 protects cultured chondrocytes from IL-1β-induced inflammatory injury by inhibiting NLRP3 inflammasome activation via the AdipoR1/AMPK axis. This work underscores a potential role of CTRP9 in the progression of osteoarthritis.

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.

ATPase inhibitory factor 1 protects the heart from acute myocardial ischemia/reperfusion injury through activating AMPK signaling pathway

Rationale: Myocardial ischemia/reperfusion (I/R) injury is a common clinic scenario that occurs in the context of reperfusion therapy for acute myocardial infarction (AMI). The mitochondrial F1Fo-ATPase inhibitory factor 1 (IF1) blocks the reversal of the F1Fo-ATP synthase to prevent detrimental consumption of cellular ATP and associated demise. In the present study, we study the role and mechanism of IF1 in myocardial I/R injury.

Methods: Mice were ligated the left anterior descending coronary artery to build the I/R model in vivo. Rat hearts were isolated and perfused with constant pressure according to Langendorff. Also, neonatal cardiomyocytes hypoxia-reoxygenation (H/R) model was also used. Myocardial infarction area, cardiac function, cellular function, and cell viability was conducted and compared.

Results: Our data revealed that IF1 is upregulated in hearts after I/R and cardiomyocytes with hypoxia/re-oxygenation (H/R). IF1 delivered with adenovirus and adeno-associated virus serotype 9 (AAV9) ameliorated cardiac dysfunction and pathological development induced by I/R ex vivo and in vivo. Mechanistically, IF1 stimulates glucose uptake and glycolysis activity and stimulates AMPK activation during in vivo basal and I/R and in vitro OGD/R conditions, and activation of AMPK by IF1 is responsible for its cardioprotective effects against H/R-induced injury.

Conclusions: These results suggest that increased IF1 in the I/R heart confer cardioprotective effects via activating AMPK signaling. Therefore, IF1 can be used as a potential therapeutic target for the treatment of pathological ischemic injury and heart failure.

Activation of AdipoR1 with rCTRP9 Preserves BBB Integrity through the APPL1/AMPK/Nrf2 Signaling Pathway in ICH Mice

Background

The disruption of the blood brain barrier (BBB) is the key factor leading to neurological impairment after intracerebral hemorrhage (ICH) injury. Adiponectin receptor 1 (AdipoR1) has an important effect contributing to the integrity of BBB. As a homologue of adiponectin, recombinant C1q/TNF-related protein 9 (rCTRP9) has neuroprotective effect in cerebrovascular diseases. The aim of this study was to investigate the protective effect of AdipoR1 activation with rCTRP9 on BBB integrity after ICH injury and the potential mechanisms.

Methods

177 male mice were subjected in this study. ICH was induced by injecting collagenase into the right basal ganglia. rCTRP9 was treated intranasally at 1 hour after ICH. Selective siRNA was administered prior to ICH. Western blot, immunofluorescence staining, neurobehavioral tests, and BBB permeability were evaluated.

Results

ICH increased the expression of endogenous AdipoR1 and CTRP9. Administration of rCTRP9 ameliorated neurological deficits and reduced the BBB permeability at 24 hours in ICH mice. Furthermore, rCTRP9 promoted the expression of AdipoR1, APPL1, p-AMPK, Nrf2, and tight junctional proteins. The intervention of specific siRNA of AdipoR1, APPL1, and p-AMPK reversed the protective effects of rCTRP9.

Conclusions

Activation of AdipoR1 with rCTRP9 improved neurological functions and preserved BBB integrity through the APPL1/AMPK/Nrf2 signaling pathway in ICH mice. Therefore, CTRP9 could serve as a promising therapeutic method to alleviate BBB injury following ICH in patients.

AMPK modulation ameliorates dominant disease phenotypes of CTRP5 variant in retinal degeneration

Late-onset retinal degeneration (L-ORD) is an autosomal dominant disorder caused by a missense substitution in CTRP5. Distinctive clinical features include sub-retinal pigment epithelium (RPE) deposits, choroidal neovascularization, and RPE atrophy. In induced pluripotent stem cells-derived RPE from L-ORD patients (L-ORD-iRPE), we show that the dominant pathogenic CTRP5 variant leads to reduced CTRP5 secretion. In silico modeling suggests lower binding of mutant CTRP5 to adiponectin receptor 1 (ADIPOR1). Downstream of ADIPOR1 sustained activation of AMPK renders it insensitive to changes in AMP/ATP ratio resulting in defective lipid metabolism, reduced Neuroprotectin D1(NPD1) secretion, lower mitochondrial respiration, and reduced ATP production. These metabolic defects result in accumulation of sub-RPE deposits and leave L-ORD-iRPE susceptible to dedifferentiation. Gene augmentation of L-ORD-iRPE with WT CTRP5 or modulation of AMPK, by metformin, re-sensitize L-ORD-iRPE to changes in cellular energy status alleviating the disease cellular phenotypes. Our data suggests a mechanism for the dominant behavior of CTRP5 mutation and provides potential treatment strategies for L-ORD patients.

CTRP6(C1q/Tumor Necrosis Factor (TNF)-related protein-6) alleviated the sevoflurane induced injury of mice central nervous system by promoting the expression of p-Akt (phosphorylated Akt)

Postoperative cognitive impairment and nervous system damage caused by anesthetics seriously affect patient’s postoperative recovery. Recent study has revealed that CTRP6 could alleviate apoptosis, inflammation and oxidative stress of nerve cells, thereby relieving nervous system damage induced by cerebral ischemia reperfusion. However, whether CTRP6 could relieve sevoflurane induced central nervous system injury is unclear. We stimulated C57BL/6 mice with sevoflurane and injected CTRP6 overexpression adenovirus vector. Next, H&E staining and TUNEL assays were performed to examine the effect of CTRP6 on sevoflurane induced injury of central nervous system. Finally, we isolated primary nerve cells of hippocampus. Flow cytometry and commercial kits were used for the detection of apoptosis and ROS levels of these cells. Western blotting was used for the detection of the expression level of p-Akt in central nervous tissues and primary cells. Results showed that sevoflurane induced injury and apoptosis of central nervous tissues. Overexpression of CTRP6 relieved apoptosis and injury of these tissues. CTRP6 inhibited the expression of cleaved caspase-3 and cleaved PARP in these tissues. Sevoflurane promoted apoptosis of primary cells and enhanced the expression of ROS and MDA in these cells. Overexpression of CTRP6 alleviated apoptosis and suppressed production of ROS and MDA in these cells. In addition, CTRP6 also enhanced the expression of p-Akt in primary cells. Taken together, our results suggested that CTRP6 relieved sevoflurane induced injury of central nervous tissues by promoting the expression of p-Akt. Therefore, the targeted drug of CTRP6 should be explored for the remission of these symptoms.

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.

C1q/TNF-related Protein 9 Inhibits High Glucose-Induced Oxidative Stress and Apoptosis in Retinal Pigment Epithelial Cells Through the Activation of AMPK/Nrf2 Signaling Pathway

Diabetic retinopathy (DR) is one of the common complications of diabetes mellitus. C1q/TNF-related protein 9 (CTRP9) has been demonstrated to be associated with the progression of diabetes and relative complications. However, its role in DR and underlying action of mechanism are not yet well understood. In the present study, human retinal pigment epithelial ARPE-19 cells were cultured under high concentration of glucose to simulate hyperglycemia condition in vitro. Our results showed that the expression of CTRP9 was significantly decreased in high glucose (HG)–stimulated ARPE-19 cells. CTRP9 overexpression improved HG-caused reduction in cell viability of ARPE-19 cells. CTRP9 overexpression significantly attenuated HG-induced oxidative stress, as proved by decreased levels of reactive oxygen species and malondialdehyde, and increased superoxide dismutase activity. Moreover, CTRP9 also prevented apoptosis in ARPE-19 cells in response to HG stimulation with decreased caspse-3 activity and bax expression, as well as increased bcl-2 expression. In contrast, knockdown of CTRP9 aggravated HG-induced oxidative stress and apoptosis. Furthermore, CTRP9 significantly induced the activation of AMPK/Nrf2 pathway in HG-induced ARPE-19 cells. Notably, inhibiting AMPK or Nrf2 blocked the protective effect of CTRP9 on ARPE-19 cells exposed to HG stimulation. Taken together, our findings suggested a protective effect of CTRP9 on HG-induced ARPE-19 cells and a putative mechanism involving the activation of AMPK/Nrf2 signaling pathway.

BCL-6 promotes the methylation of miR-34a by recruiting EZH2 and upregulating CTRP9 to protect ischemic myocardial injury

Acute myocardial infarction (AMI) and the following heart failure are public health problems faced all over the globe. The current study set out to investigate the role of B-cell lymphoma 6 (BCL-6) in cardiac protection after AMI. Initially, AMI mouse models and H9c2 cell oxygen-glucose deprivation (OGD) models were established. The cell models were transfected with the vectors containing oe-BCL-6, oe-EZH2, sh-EZH2, miR-34a mimic, and miR-34a inhibitor. RT-qPCR and Western blot analysis were applied to detect the expression patterns of microRNA-34a (miR-34a), BCL-6, enhancer of zeste homolog 2 (EZH2), and C1q tumor necrosis factor-related protein 9 (CTRP9) in the treated cell models. ChIP-qPCR and co-immunoprecipitation assay were performed to detect EZH2 enrichment and H3K27me3 levels in the miR-34a promoter region and the interaction between BCL-2 and EZH2, respectively. EdU staining, TUNEL staining, and flow cytometry were performed to detect cell proliferation and apoptosis, while ELISA was conducted to detect the oxidative stress levels. It was found that miR-34a was highly expressed in heart tissues of AMI models, while BCL-6 and EZH2 were poorly expressed. BCL-2 overexpression increased the recruitment of EZH2, upregulated H3K27me3 level in the miR-34a promoter region, and inhibited the miR-34a expression. Ctrp9, the downstream negative-regulatory molecule of miR-34a, was upregulated. Besides, miR-34a/CTRP9 expression changes were found to affect cardiomyocyte apoptosis, oxidation stress, and proliferation, and prevent myocardial injury in AMI mice. Our findings indicate that BCL-6 increases the level of H3K27me3 in the promoter region of miR-34a via EZH2 recruitment and CTRP9 upregulation, which inhibits the apoptosis of myocardial cells.

Comparative Analysis of CTRP-Mediated Effects on Cardiomyocyte Glucose Metabolism: Cross Talk between AMPK and Akt Signaling Pathway

C1q/tumor necrosis factor -alpha-related proteins (CTRPs) have been shown to mediate protective cardiovascular effects, but no data exists on their effects on glucose and fatty acid (FA) metabolism in cardiomyocytes. In the present study, adult rat cardiomyocytes and H9C2 cardiomyoblasts were stimulated with various recombinant CTRPs. Glucose or FA uptake, expression of genes involved in glucose or FA metabolism and the role of the AMP-activated protein kinase (AMPK) and Akt were investigated. Although most CTRPs induced an increase in phosphorylation of AMPK and Akt in cardiomyocytes, mainly CTRP2, 7, 9 and 13 induced GLUT1 and GLUT4 translocation and glucose uptake in cardiomyocytes, despite high structural similarities among CTRPs. AMPK inhibition reduced the CTRPs-mediated activation of Akt, while Akt inhibition did not impair AMPK activation. In addition, CTRP2, 7, 9 and 13 mediated strong effects on the expression of enzymes involved in glucose or FA metabolism. Loss of adiponectin receptor 1, which has been suggested to be involved in CTRP-induced signal transduction, abolished the effects of some but not all CTRPs on glucose metabolism. Targeting the AMPK signaling pathway via CTRPs may offer a therapeutic principle to restore glucose homeostasis by acting on glucose uptake independent of the Akt pathway.

Identification of a CTRP9 C-Terminal polypeptide capable of enhancing bone-derived mesenchymal stem cell cardioprotection through promoting angiogenic exosome production

BACKGROUND

Mesenchymal stem cell therapy improves ischemic heart failure via incompletely understood mechanisms. C1q-TNFα related protein-9 (CTRP9) is a novel anti-oxidative cardiokine capable of improving the local microenvironment and cell survival by its c-terminal active globular domain (gCTRP9). The current study attempted to: 1) identify active gCTRP9 c-terminal polypeptides with stem cell protective function; 2) determine whether a lead polypeptide may enable/enhance cortical bone-derived mesenchymal stem cell (CBSC) cardioprotection against post-myocardial infarction (post-MI) remodeling; and 3) define the responsible underlying cellular/molecular mechanisms.

METHODS AND RESULTS

Utilizing I-TASSER structure prediction and 3-D active site modeling, we cloned and purified 3 gCTRP9 fragments (CTRP9-237, CTRP9-277, and CTRP9-281). Their activation of cell salvage kinase was compared against gCTRP9. Among the three fragments, CTRP9-281 (a 45 residue-containing polypeptide) exerted comparable or greater ERK1/2 activation compared to gCTRP9. Treatment with CTRP9-281 or gCTRP9 significantly increased CBSC proliferation and migration, and attenuated oxidative stress-induced CBSC apoptosis. CTRP9-281 and gCTRP9 comparably upregulated SOD2 and SOD3 expression. However, CTRP9-281, not gCTRP9, upregulated FGF2 and VEGFA expression/secretion in an ERK1/2 dependent manner. Administration of gCTRP9 or CTRP9-281 alone attenuated post-MI cardiac dysfunction and improved CBSC retention in the infarcted heart in similar fashion. However, CTRP9-281 exerted greater synergistic effect with CBSC than gCTRP9 related to pro-angiogenic, anti-fibrotic, and anti-remodeling effects. Mechanistically, CTRP9-281 significantly increased SOD2-rich and VEGFA-rich exosome production by CBSC. Exosomes from CTRP9-281 treated CBSC significantly attenuated oxidative stress-induced cardiomyocyte apoptosis in vitro. An exosome generation inhibitor attenuated CTRP9-281 enhancement of CBSC cardioprotection in vivo.

CONCLUSION

We identified a CTRP9 polypeptide that upregulates SOD2/SOD3 expression and improves CBSC survival/retention, similar to gCTRP9. Moreover, CTRP9-281 stimulates VEGFA-rich exosome production by CBSC, exerting superior pro-angiogenic, anti-fibrotic, and cardioprotective actions.

CTRP9 alleviates foam cells apoptosis by enhancing cholesterol efflux

The apoptosis of foam cells leads to instability of atherosclerotic plaques. This study was designed to explore the protective role of CTRP9 in foam cell apoptosis. In our experiment, CTRP9 alleviated foam cell apoptosis. Meanwhile, CTRP9 upregulated the expression of proteins important for cholesterol efflux, such as LXRα, CYP27A1, ABCG1 and ABCA1, and improved cholesterol efflux in foam cells. Moreover, CTRP9 inhibited Wnt3a and β-catenin expression and β-catenin nuclear translocation in foam cells. In addition, adenovirus overexpression of Wnt3a abolished the effect of CTRP9 on macrophage apoptosis. Mechanistically, the AMPK inhibitor abolished the effect of CTRP9 on foam cell apoptosis, and downregulation of AdipoR1 by siRNA abrogated the activation of AMPK and the effect of CTRP9 on foam cell apoptosis. We concluded that CTRP9 achieved these protective effects on foam cells through the AdipoR1/AMPK pathway.

Impact of PCSK9 on CTRP9-Induced Metabolic Effects in Adult Rat Cardiomyocytes

The adipocytokine adiponectin and its structural homologs, the C1q/TNF-related proteins (CTRPs), increase insulin sensitivity, fatty acid oxidation and mitochondrial biogenesis. Adiponectin- and CTRP-induced signal transduction has been described to involve the adiponectin receptors and a number of co-receptors including the Low density lipoprotein receptor-related protein 1 (LRP1). LRP1 is another target of the proprotein convertase subtilisin/kexin-9 (PCSK9) in addition to the LDL-receptor (LDL-R). Here, we investigated the influence of PCSK9 on the metabolic effects of CTRP9, the CTRP with the highest homology to adiponectin. Knockdown of LRP1 in H9C2 cardiomyoblasts blunts the effects of CTRP9 on signal transduction and mitochondrial biogenesis, suggesting its involvement in CTRP9-induced cellular effects. Treatment of adult rat cardiomyocytes with recombinant PCSK9 but not knockdown of endogenous PCSK9 by siRNA results in a strong reduction in LRP1 protein expression and subsequently reduces the mitochondrial biogenic effect of CTRP9. PCSK9 treatment (24 h) blunts the effects of CTRP9-induced signaling cascade activation (AMP-dependent protein kinase, protein kinase B). In addition, the stimulating effects of CTRP9 on cardiomyocyte mitochondrial biogenesis and glucose metabolism (GLUT-4 translocation, glucose uptake) are largely blunted. Basal fatty acid (FA) uptake is strongly reduced by exogenous PCSK9, although protein expression of the PCSK9 target CD36, the key regulator of FA transport in cardiomyocytes, is not altered. In addition, only minor effects of PCSK9 were observed on CTRP9-induced FA uptake or the expression of genes involved in FA metabolism or uptake. Finally, this CTRP9-induced increase in CD36 expression occurs independent from LRP1 and LDL-R. In conclusion, PCSK9 treatment influences LRP1-mediated signaling pathways in cardiomyocytes. Thus, therapeutic PCSK9 inhibition may provide an additional benefit through stimulation of glucose metabolism and mitochondrial biogenesis in addition to the known lipid-lowering effects. This could be an important beneficial side effect in situations with impaired mitochondrial function and reduced metabolic flexibility thereby influencing cardiac function.

Diagnostic value and prognostic significance of CTRP9 combined with pentraxin-3 in acute coronary syndrome

The present study aimed to explore the diagnostic value and prognostic significance of C1q/tumor necrosis factor-related protein 9 (CTRP9) combined with pentraxin-3 (PTX-3) in acute coronary syndrome (ACS). A total of 137 patients with coronary heart disease and chest pain were included. Among them, seventy-nine patients with ACS were allocated into a study group and fifty-eight patients with non-cardiac chest pain (NCCP) were allocated into a control group. The serum CTRP9, PTX-3 levels were quantified by ELISA, and their correlation with other ACS-related indexes, diagnostic value for ACS and predictive significance for poor prognosis were analyzed. In addition, the risk factors of the poor prognosis of ACS patients were studied. CTRP9 was lowly expressed and PTX-3 was highly expressed in the serum of ACS patients. CTRP9 was negatively correlated with cardiac troponin I (cTnI), creatine kinase-MB (CK-MB) and high-sensitivity C-reactive protein (hs-CRP) (P<0.05), while PTX-3 was positively correlated with them (P<0.05). Combined detection of CTRP9 and PTX-3 was of high value in the diagnosis and prognosis of ACS patients. In addition, CTRP9 and PTX-3 were independent risk factors for the poor prognosis of ACS. Patients with ACS had lower CTRP9 expression and higher PTX-3 expression than those without ACS. Moreover, the combined detection of CTRP9 and PTX-3 can better evaluate the diagnosis and prognosis of ACS patients.

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.

CTRP5-Overexpression Attenuated Ischemia-Reperfusion Associated Heart Injuries and Improved Infarction Induced Heart Failure

Aims: C1q/tumor necrosis factor (TNF)-related protein 5 (CTRP5) belongs to the C1q/TNF-α related protein family and regulates glucose, lipid metabolism, and inflammation production. However, the roles of CTRP5 in ischemia/reperfusion (I/R) associated with cardiac injuries and heart failure (HF) needs to be elaborated. This study aimed to investigate the roles of CTRP5 in I/R associated cardiac injuries and heart failure.

Materials and Methods: Adeno-associated virus serum type 9 （AAV9）vectors were established for CTRP5 overexpression in a mouse heart (AAV9-CTRP5 mouse). AAV9-CTRP5, AMPKα2 global knock out （AMPKα2^−/−）and AAV9-CTRP5+ AMPKα2^−/− mice were used to establish cardiac I/R or infarction associated HF models to investigate the roles and mechanisms of CTRP5 in vivo. Isolated neonatal rat cardiomyocytes (NRCMS) transfected with or without CTRP5 adenovirus were used to establish a hypoxia/reoxygenation (H/O) model to study the roles and mechanisms of CTRP5 in vitro.

Key Findings: CTRP5 was up-regulated after MI but was quickly down-regulated. CTRP5 overexpression significantly decreased I/R induced IA/AAR and cardiomyocyte apoptosis, and attenuated infarction area, and improved cardiac functions. Mechanistically, CTRP5 overexpression markedly increased AMPKα2 and ACC phosphorylation and PGC1-α expression but inhibited mTORC1 phosphorylation. In in vitro experiments, CTRP5 overexpression could also enhance AMPKα2 and ACC phosphorylation and protect against H/O induced cardiomyocytes apoptosis. Finally, we showed that CTPR5 overexpression could not protect against I/R associated cardiac injuries and HF in AMPKα2^−/− mice.

Significance: CTRP5 overexpression protected against I/R induced mouse cardiac injuries and attenuated myocardial infarction induced cardiac dysfunction by activating the AMPKαsignaling pathway.

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.

Adipolin/C1q/Tnf-related protein 12 prevents adverse cardiac remodeling after myocardial infarction

Background

Myocardial infarction (MI) is a leading cause of death worldwide. We previously identified adipolin, also known as C1q/Tnf-related protein 12, as an anti-inflammatory adipokine with protective features against metabolic and vascular disorders. Here, we investigated the effect of adipolin on myocardial remodeling in a mouse model of MI.

Methods

Male adipolin-knockout (APL-KO) and wild-type (WT) mice were subjected to the permanent ligation of the left anterior descending coronary artery to create MI.

Results

APL-KO mice exhibited increased ratios of heart weight/body weight and lung weight/body weight after MI compared with WT mice. APL-KO mice showed increased left ventricular diastolic diameter and decreased fractional shortening after MI compared with WT mice. APL-KO mice exhibited increased expression of pro-inflammatory mediators and enhanced cardiomyocyte apoptosis in the post-MI hearts compared with WT mice. Systemic administration of adenoviral vectors expressing adipolin to WT mice after MI surgery improved left ventricular contractile dysfunction and reduced cardiac expression of pro-inflammatory genes. Treatment of cultured cardiomyocytes with adipolin protein reduced lipopolysaccharide-induced expression of pro-inflammatory mediators and hypoxia-induced apoptosis. Treatment with adipolin protein increased Akt phosphorylation in cardiomyocytes. Inhibition of PI3 kinase/Akt signaling reversed the anti-inflammatory and anti-apoptotic effects of adipolin in cardiomyocytes.

Conclusion

Our data indicate that adipolin ameliorates pathological remodeling of myocardium after MI, at least in part, by its ability to reduce myocardial inflammatory response and apoptosis.

CTRP15 derived from cardiac myocytes attenuates TGFβ1-induced fibrotic response in cardiac fibroblasts

PURPOSE

Cardiac fibrosis is characterized by net accumulation of extracellular matrix (ECM) components in the  myocardium and facilitates the development of heart failure. C1q/tumor necrosis factor-related protein 15 (CTRP15) is a novel member of the CTRP family, and its gene expression is detected in adult mouse hearts. The present study was performed to determine the effect of CTRP15 on pressure overload-induced fibrotic remodeling.

METHODS

Mice were subjected to transverse aortic constriction (TAC) surgery, and adeno-associated virus serotype 9 (AAV9)-carrying mouse CTRP15 gene was injected into mice to achieve CTRP15 overexpression in the myocardium. Adenovirus carrying the gene encoding CTRP15 or small interfering RNA (siRNA) of interest was infected into cultured neonatal mouse ventricular cardiomyocytes (NMVCs) or cardiac fibroblasts (CFs). Gene expression was measured by quantitative real-time PCR, and protein expression and distribution were determined by Western blotting, immunocytochemistry, and immunofluorescence staining.

RESULTS

CTRP15 was predominantly produced by cardiac myocytes. CTRP15 expression in the left ventricles was downregulated in mice that underwent TAC. AAV9-mediated CTRP15 overexpression alleviated ventricular remodeling and dysfunction in the pressure-overloaded mice. Treatment of CFs with recombinant CTRP15 or the conditioned medium containing CTRP15 inhibited transforming growth factor (TGF)-β1-induced Smad3 activation and myofibroblast differentiation. CTRP15 increased phosphorylation of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), and Akt. Blockade of IR/IRS-1/Akt pathway reversed the inhibitory effect of CTRP15 on TGF-β1-induced Smad3 activation.

CONCLUSION

CTRP15 exerts an anti-fibrotic effect on pressure overload-induced cardiac remodeling. The activation of IR/IRS-1/Akt pathway contributes to the anti-fibrotic effect of CTRP15 through targeting Smad3.

Adipose Tissue Immunomodulation: A Novel Therapeutic Approach in Cardiovascular and Metabolic Diseases

Adipose tissue is a critical regulator of systemic metabolism and bodily homeostasis as it secretes a myriad of adipokines, including inflammatory and anti-inflammatory cytokines. As the main storage pool of lipids, subcutaneous and visceral adipose tissues undergo marked hypertrophy and hyperplasia in response to nutritional excess leading to hypoxia, adipokine dysregulation, and subsequent low-grade inflammation that is characterized by increased infiltration and activation of innate and adaptive immune cells. The specific localization, physiology, susceptibility to inflammation and the heterogeneity of the inflammatory cell population of each adipose depot are unique and thus dictate the possible complications of adipose tissue chronic inflammation. Several lines of evidence link visceral and particularly perivascular, pericardial, and perirenal adipose tissue inflammation to the development of metabolic syndrome, insulin resistance, type 2 diabetes and cardiovascular diseases. In addition to the implication of the immune system in the regulation of adipose tissue function, adipose tissue immune components are pivotal in detrimental or otherwise favorable adipose tissue remodeling and thermogenesis. Adipose tissue resident and infiltrating immune cells undergo metabolic and morphological adaptation based on the systemic energy status and thus a better comprehension of the metabolic regulation of immune cells in adipose tissues is pivotal to address complications of chronic adipose tissue inflammation. In this review, we discuss the role of adipose innate and adaptive immune cells across various physiological and pathophysiological states that pertain to the development or progression of cardiovascular diseases associated with metabolic disorders. Understanding such mechanisms allows for the exploitation of the adipose tissue-immune system crosstalk, exploring how the adipose immune system might be targeted as a strategy to treat cardiovascular derangements associated with metabolic dysfunctions.

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.

C1q/TNF-Related Protein 9 Promotes Revascularization in Response to Ischemia via an eNOS-Dependent Manner

Strategies to promote revascularization are valuable for ischemic cardiovascular disease. Although C1q/TNF-related protein (CTRP) 9 is an adiponectin paralog with protective properties against cardiometabolic disorders, the role of endogenous CTRP9 in endothelial function is largely unknown. This study aimed to investigate the effects of CTRP9 on revascularization processes and dissected the potential mechanisms. CTRP9-knockout (KO) and wild-type (WT) mice were subjected to unilateral hindlimb ischemic surgery. CTRP9-KO mice exhibited impaired blood flow recovery and decreased capillary density in the ischemic limb compared with WT mice. In both CTRP9-KO and WT mice, systemic delivery of an adenoviral vector expressing CTRP9 (Ad-CTRP9) accelerated blood flow recovery. Treatment with recombinant CTRP9 protein increased network formation and migration of cultured human umbilical vein endothelial cells (HUVECs). CTRP9 promoted the phosphorylation of AMP-activated kinase (AMPK), Akt, and endothelial nitric oxide synthase (eNOS) in HUVECs. CTRP9-KO mice also showed reduced phosphorylation levels of AMPK, Akt, and eNOS in the ischemic limbs compared with WT mice. Furthermore, blockade of AMPK or Akt signaling pathway reversed the CTRP9-stimulated eNOS phosphorylation in HUVECs. Treatment with the NOS inhibitor significantly reduced CTRP9-stimulated network formation and migration of HUVECs. Of note, Ad-CTRP9 had no effects on blood flow of the ischemic limb in eNOS-KO mice. These results indicated that CTRP9 promotes endothelial cell function and ischemia-induced revascularization through the eNOS-dependent mechanism, suggesting that CTRP9 represents a target molecule for treatment of ischemic vascular diseases.

The role of adiponectin in ischemia-reperfusion syndrome: a literature review

Adiponectin, among other diverse adipokines, is produced in greater quantity and has an effect on the adipose tissue and other tissues in the body. Adiponectin plays three main roles: regulatory metabolic and sensitizing function of insulin in the liver and muscles; it acts as an anti-inflammatory cytokine and in vascular protection, besides important cardiac protection in the presence of ischemia-reperfusion syndrome. Since many situations resulting from traumatic accidents or pathologies are due to cell damage caused by ischemia-reperfusion syndrome, it is relevant to study new therapeutic alternatives that will contribute to reducing these lesions. The objective of this study is to carry out a literature review on the role of adiponectin in ischemia-reperfusion syndrome.

Predictive value of serum CTRP9 and STIM1 for restenosis after cerebrovascular stent implantation and its relationship with vasoactive substances and inflammatory cytokines

Predictive value of serum complement Clq tumor necrosis factor-related protein 9 (CTRP9) and serum stromal interaction molecule 1 (STIM1) was investigated for restenosis after cerebrovascular stent implantation, as well as its relationship with vasoactive substances and inflammatory cytokines. In this prospective study, 128 patients with cerebral infarction treated with cerebrovascular stent implantation in Yantaishan Hospital were recruited. A total of 66 cases with restenosis after cerebrovascular stent implantation were included in group A, and 62 cases without stenosis were included in group B. Serum CTRP9 and STIM1 levels were measured by enzyme-linked immunosorbent assay (ELISA). ROC curves of serum CTRP9 and STIM1 levels in patients with postoperative restenosis were drawn. The vasoactive substances nitric oxide (NO), tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) were analyzed by ELISA. The correlation of serum CTRP9, STIM1 levels and NO, TNF-α, IL-6 were analyzed by Pearson correlation coefficient. Serum CTRP9 and NO levels in group A were significantly lower than those in group B. The levels of serum STIM1, TNF-α and IL-6 in group A were significantly higher than those in group B (P<0.001). The sensitivity and specificity of serum CTRP9 level in the diagnosis of restenosis after cerebrovascular stent implantation were, respectively, 59.68 and 75.76%. Those of serum STIM1 were, respectively, 87.10 and 46.97% and those of the combination of serum CTRP9 and STIM1 were 90.32 and 48.48%. Serum CTRP9 level was positively correlated with NO, and negatively correlated with TNF-α and IL-6. STIM1 was positively correlated with TNF-α and IL-6, and negatively correlated with NO (P<0.001). Serum CTRP9 level was significantly decreased in patients with restenosis after cerebrovascular stent implantation, while STIM1 level was significantly up-regulated. Both were correlated with the change of NO, IL-6 and TNF-α levels, therefore they could be used as biological indicators for prediction of restenosis after cerebrovascular stent implantation.

A Review of the Relationship Between CTRP Family and Coronary Artery Disease

Purpose of Review

In recent years, a family of adiponectin paralogs designated as C1q/TNF-related protein (CTRP) has attracted increasing attention. They are inflammatory adipocytokines mostly secreted from epicardial adipose tissue, which modulate the development and prognosis of coronary artery disease (CAD). This review summarizes the pathophysiological roles of individual members of the CTRP superfamily in the development of CAD.

Recent Findings

Recent studies have revealed how members of the CTRP family, CTRP1, CTRP3, CTRP5, CTRP9, CTRP12, and CTRP13, can influence both development and progression of CAD by modulating metabolic pathways, influencing immuno-inflammatory response, and regulating cardiovascular functions.

Summary

Research to date has not been sufficient to answer the specific mechanism of the CTRP family in the occurrence and development of CAD. This review explores the evidence of CTRP superfamily regulating different pathophysiology stages of CAD through the immuno-inflammation, glucose and lipid metabolism, and vascular endothelial function.

CTRP9 Mediates Protective Effects in Cardiomyocytes via AMPK- and Adiponectin Receptor-Mediated Induction of Anti-Oxidant Response

The C1q/tumor necrosis factor-alpha-related protein 9 (CTRP9) has been reported to exert cardioprotective effects, but its role in the right ventricle (RV) remains unclear. To investigate the role of CTRP9 in RV hypertrophy and failure, we performed pulmonary artery banding in weanling rats to induce compensatory RV hypertrophy seven weeks after surgery and RV failure 22 weeks after surgery. CTRP9 expression, signal transduction and mechanisms involved in protective CTRP9 effects were analyzed in rat and human RV tissue and cardiac cells. We demonstrate that CTRP9 was induced during compensatory RV hypertrophy but almost lost at the stage of RV failure. RV but not left ventricular (LV) cardiomyocytes or RV endothelial cells demonstrated increased intracellular reactive oxygen species (ROS) and apoptosis activation at this stage. Exogenous CTRP9 induced AMP-activated protein kinase (AMPK)-dependent transcriptional activation of the anti-oxidant thioredoxin-1 (Trx1) and superoxide dismutase-2 (SOD2) and reduced phenylephrine-induced ROS. Combined knockdown of adiponectin receptor-1 (AdipoR1) and AdipoR2 or knockdown of calreticulin attenuated CTRP9-mediated anti-oxidant effects. Immunoprecipitation showed an interaction of AdipoR1 with AdipoR2 and the co-receptor T-cadherin, but no direct interaction with calreticulin. Thus, CTRP9 mediates cardioprotective effects through inhibition of ROS production induced by pro-hypertrophic agents via AMPK-mediated activation of anti-oxidant enzymes.

Abnormalities of Skeletal Muscle, Adipocyte Tissue, and Lipid Metabolism in Heart Failure: Practical Therapeutic Targets

Chronic diseases, including heart failure (HF), are often accompanied with skeletal muscle abnormalities in both quality and quantity, which are the major cause of impairment of the activities of daily living and quality of life. We have shown that skeletal muscle abnormalities are a hallmark of HF, in which metabolic pathways involving phosphocreatine and fatty acids are largely affected. Not only in HF, but the dysfunction of fatty acid metabolism may also occur in many chronic diseases, such as arteriosclerosis, as well as through insufficient physical exercise. Decreased fatty acid catabolism affects adenosine triphosphate (ATP) production in mitochondria, via decreased activity of the tricarboxylic acid cycle; and may cause abnormal accumulation of adipose tissue accompanied with hyperoxidation and ectopic lipid deposition. Such impairments of lipid metabolism are in turn detrimental to skeletal muscle, which is hence a chicken-and-egg problem between skeletal muscle and HF. In this review, we first discuss skeletal muscle abnormalities in HF, including sarcopenia; particularly their association with lipid metabolism and adipose tissue. On the other hand, the precise mechanisms involved in metabolic reprogramming and dysfunction are beginning to be understood, and an imbalance of daily nutritional intake of individuals has been found to be a causative factor for the development and worsening of HF. Physical exercise has long been known to be beneficial for the prevention and even treatment of HF. Again, the molecular mechanisms by which exercise promotes skeletal muscle as well as cardiac muscle functions are being clarified by recent studies. We propose that it is now the time to develop more “natural” methods to prevent and treat HF, rather than merely relying on drugs and medical interventions. Further analysis of the basic design of and molecular mechanisms involved in the human body, particularly the inextricable association between physical exercise and the integrity and functional plasticity of skeletal and cardiac muscles is required.