Adipokine CTRP6 improves PPARγ activation to alleviate angiotensin II-induced hypertension and vascular endothelial dysfunction in spontaneously hypertensive rats

C1q/tumor necrosis factor-related protein-6 suppresses the angiotensin II-induced differentiation of cardiac fibroblasts to myofibroblasts via activation of the AMPK pathway

C1q/tumor necrosis factor-related protein-6 (CTRP6) has multiple protective effects against cardiovascular diseases. Myofibroblast differentiation plays a critical role in cardiac fibrosis under various cardiac pathological conditions. The aim of the present study was to determine the effects of CTRP6 on cardiac fibrosis, and to identify the possible mechanisms of action. Toward this end, we measured the expression of fibrotic markers, including collagen I, collagen III, CTGF, and TGFβ1, and assessed the effects of CTRP6 on cardiac fibroblast differentiation into myofibroblasts. CTRP6 inhibited the expression of the angiotensin II (Ang II)-induced myofibroblast markers α-SMA and SM22, and of profibrotic molecules, including collagen I, collagen III, CTGF, TGFβ1, MMP2, MMP9, and TIMP1. Furthermore, CTRP6 significantly attenuated the proliferation and migration of cardiac fibroblasts incubated with Ang II and activated the phosphorylation of AMP-activated protein kinase (AMPK). Incubation with an AMPK inhibitor reversed the subsequent inhibitory effects of CTRP6 on Ang II-induced myofibroblast differentiation. Therefore, CTRP6 suppresses cardiac fibrosis by inhibition of myofibroblast differentiation via AMPK pathway activation, suggesting CTRP6 as a target for the treatment of cardiac fibrosis.

Circulating levels of C1q/TNF-α-related protein 6 (CTRP6) in coronary artery disease and its correlation with inflammatory markers

Introduction

Circulating levels of C1q/TNF-α-related protein 6 (CTRP6) is an adipokine that is involved in regulation of glucose and lipid metabolism, inflammation, and insulin sensitivity. However, the exact role of CTRP6 in metabolic processes remains unclear due to conflicting findings. To address current gap, we aimed to investigate the serum levels of CTRP6 in patients with coronary artery disease (CAD) and its association with inflammatory cytokines.

Method

In this case-control study, the serum levels of CTRP6, interlukin-6 (IL-6), tumor necrosis factor- α (TNF-α), adiponectin, and fasting insulin were measured using enzyme-linked immunosorbent assay (ELISA) kits in a total of 176 participants, consisting of 88 CAD patients and 88 control subjects. Additionally, various anthropometric and biochemical measurements were measured and compared between cases and controls.

Results

The present study found that serum levels of CTRP6 were significantly higher in the CAD group (561.3 ± 15.14) compared to the control group (429.3 ± 12.85, p < 0.001). After adjusting for age, sex, and body mass index (BMI), CTRP6 levels were found to be positively associated with the risk of CAD (p < 0.001). Correlation analysis in CAD subjects revealed a positive correlation between CTRP6 levels and BMI, systolic blood pressure (SBP), malondialdehyde (MDA), TNF-α, and IL-6, as well as a negative correlation with creatinine and total anti-oxidant capacity.

Conclusion

The findings of this study provide novel evidence that elevated serum levels of CTRP6 are significantly associated with an increased risk of developing CAD. Moreover, our results indicate a correlation between CTRP6 and various risk factors for atherosclerosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01415-5.

Role of C1q/TNF-Related Protein 6 for the Evaluation of Coronary Heart Disease Associated with Type 2 Diabetes

Objective

Coronary artery disease (CAD) and type 2 diabetes (T2DM) are closely associated with increased rate of death. C1q/TNF-related protein 6 (CTRP6) is a novel adipocytokine which plays an important role in glucose and lipid metabolism. Little is known about the function of CTRP6 in CAD and T2DM patients. Herein, we aimed to study the association of CTRP6 level with CAD and T2DM.

Methods

This study included 51 CAD, 44 CAD+T2DM and 65 non-CAD+T2DM patients from Affiliated Aoyang Hospital of Jiangsu University. Serum CTRP6 concentrations were detected by ELISA. Multiple logistic regression was used to analyze the association of serum CTRP6 with CAD and T2DM.

Results

Serum CTRP6 concentrations were significantly lower in CAD patients than controls. However, there is no significant statistical difference between CAD+T2DM patients and non-CAD+T2DM patients. Serum CTRP6 was negatively correlated with low-density lipoprotein cholesterol (LDL-C) (ρ=-0.2769, p=0.028) in controls. Serum CTRP6 was positively correlated with age (ρ=0.4121, p=0.0027), systolic blood pressure (SBP) (ρ=0.4012, p=0.0035), Creatinine (ρ=0.3295, p=0.0194), uric acid (UA) (ρ=0.3386, p=0.0162), and left ventricular end diastolic diameter (LVD) (ρ=0.4277, p=0.0042) and negatively correlated with ejection fraction (EF) (ρ=-0.3237, p=0.0342) in CAD patients. Serum CTRP6 was negatively correlated with high-density lipoprotein cholesterol (HDL-C) (ρ=-0.3164, p=0.0387) in CAD+T2DM patients. Multiple logistic regression showed that the decrease of CTRP6 was significantly related to the increased prevalence of CAD. What is more, CTRP6 increased prevalence of T2DM in CAD patients.

Conclusion

Lower serum CTRP6 could be a risk factor of CAD. However, higher circulating CTRP6 associated with the increased prevalence of T2DM in CAD patients.

Detoxification and Activating Blood Circulation Decoction Promotes Reendothelialization of Damaged Blood Vessels via VEGF Signaling Pathway Activation by miRNA-126

The occurrence of in-stent restenosis (ISR) poses a significant challenge for percutaneous coronary intervention (PCI). Thus, the promotion of vascular reendothelialization is essential to inhibit endothelial proliferation. In this study, we clarified the mechanism by which Detoxification and Activating Blood Circulation Decoction (DABCD) promotes vascular reendothelialization to avoid ISR by miRNA-126-mediated modulation of the vascular endothelial growth factor (VEGF) signaling pathway. A rat model of post-PCI restenosis was established by balloon injury. The injured aortic segment was collected 14 and 28 d after model establishment. Our findings indicate that on the 14th and 28th days following balloon injury, DABCD reduced intimal hyperplasia and inflammation and promoted vascular reendothelialization. Additionally, DABCD markedly increased nitric oxide (NO) expression and significantly decreased ET-1 production in rat serum. DABCD also increased the mRNA level of endothelial nitric oxide synthase (eNOS) and the protein expression of VEGF, p-Akt, and p-extracellular signal-regulated kinase (ERK)1/2 in vascular tissue. Unexpectedly, the expression of miR-126a-5p mRNA was significantly lower in the aortic tissue of balloon-injured rats than in the aortic tissue of control rats, and higher miR-126a-5p levels were observed in the DABCD groups. The results of this study indicated that the vascular reendothelialization effect of DABCD on arterial intimal injury is associated with the inhibition of neointimal formation and the enhancement of vascular endothelial activity. More specifically, the effects of DABCD were mediated, at least in part, through miR-126-mediated VEGF signaling pathway activation.

Knockdown of FOXO4 protects against OGD/R‑induced cerebral microvascular endothelial cell injury and regulates the AMPK/Nrf2/HO‑1 pathway through transcriptional activation of CTRP6

Cerebral ischemia is a type of cerebrovascular disease with high disability and mortality rates. The expression of forkhead box protein O4 (FOXO4) in the brain is increased following traumatic brain injury. To the best of our knowledge, however, the role of FOXO4 as well as its mechanism in cerebral ischemia has not been reported so far. For the establishment of an in vitro cellular injury model, human brain microvascular endothelial HCMEC/D3 cells were induced by oxygen-glucose deprivation/reoxygenation (OGD/R). mRNA and protein expressions of FOXO4 and C1q/tumor necrosis factor-related protein 6 (CTRP6) in OGD/R-induced HCMEC/D3 cells were detected by reverse transcription-quantitative (RT-q)PCR and western blotting. The transfection efficacy of small interfering (si)- and overexpression (Ov)-FOXO4 and si-CTRP6 was assessed using RT-qPCR and western blotting. Cell Counting Kit-8 and TUNEL assay were used to assess viability and apoptosis of HCMEC/D3 cells induced by OGD/R, respectively. A FITC-Dextran assay kit was applied to determine endothelial permeability and immunofluorescence assay was used for the measurement of the tight junction protein zonula occludens-1. The levels of oxidative stress markers and inflammatory cytokines were assessed with corresponding assay kits. The binding sites of transcription factor, FOXO4 and CTRP6 promoter were predicted using HDOCK SERVER. Luciferase reporter assay was used to detect the activity of the CTRP6 promoter while chromatin immunoprecipitation assay was used to evaluate the binding ability of the FOXO4 and CTRP6 promoter. Western blotting was used for the detection of apoptosis- and AMPK/Nrf2/heme oxygenase-1 (HO-1) pathway-associated proteins, along with tight junction proteins. The expression of FOXO4 was increased in OGD/R-induced HCMEC/D3 cells. After interfering with FOXO4 in cells, the viability of the OGD/R-induced HCMEC/D3 cells was increased while apoptosis was decreased. Furthermore, FOXO4 interference improved cellular barrier dysfunction but inhibited oxidative stress and the inflammatory response in HCMEC/D3 cells induced by OGD/R. FOXO4 knockdown regulated CTRP6 transcription in HCMEC/D3 cells. Knockdown of FOXO4 regulated expression of CTRP6 and protected OGD/R-induced HCMEC/D3 cell injury via the AMPK/Nrf2/HO-1 pathway. The present study indicated that FOXO4 knockdown activated CTRP6 to protect against cerebral microvascular endothelial cell injury induced by OGD/R via the AMPK/Nrf2/HO-1 pathway.

CTRP6 regulates M1 macrophage polarization via the PPAR-γ/NF-κB pathway and reprogramming glycolysis in recurrent spontaneous abortion

Aberrant polarization and functions of decidual macrophages are closely related to recurrent spontaneous abortion (RSA). C1q/tumor necrosis factor-related protein 6 (CTRP6) is a member of the adiponectin paralog family, and plays indispensable roles in inflammation, glucose uptake and tumor metastasis. However, the regulatory effect of CTRP6 on macrophage polarization and glycolysis in RSA and the underlying mechanisms have not been fully elucidated. In the present study, we first found that CTRP6 expression was positively correlated with the M1 macrophage marker (CD86) in decidual tissues by dual immunofluorescence analysis. In vitro experiments indicated that CTRP6 could facilitate M1 macrophage activation through the PPAR-γ/NF-κB pathway and manipulate the glycolysis of macrophages. Notably, in addition to silencing CTRP6, treatment with a PPAR-γ agonist (GW1929) inhibited M1 macrophage polarization and rescued embryo absorption in vivo. Taken together, these results identify previously unrevealed functions of CTRP6 in macrophage transformation during RSA.

Multi-faceted roles of C1q/TNF-related proteins family in atherosclerosis

Purpose of review

C1q/TNF-related proteins (CTRPs) are involved in the modulation of the development and prognosis of atherosclerosis (AS). Here, we summarizes the pathophysiological roles of individual members of the CTRP superfamily in the development of AS. Currently, there is no specific efficacious treatment for AS-related diseases, therefore it is urgent to develop novel therapeutic strategies aiming to target key molecules involved in AS.

Recent findings

Recently, mounting studies verified the critical roles of the CTRP family, including CTRP1-7, CTRP9 and CTRP11-15, in the development and progression of AS by influencing inflammatory response, modulating glucose and lipid metabolism, regulating endothelial functions and the proliferation of vascular smooth muscle cells (VSMCs).

Conclusions

CTRP family regulate different pathophysiology stages of AS. CTRP3, CTRP9, CTRP12, CTRP13 and CTRP15 play a clear protective role in AS, while CTRP5 and CTRP7 play a pro-atherosclerotic role in AS. The remarkable progress in our understanding of CTRPs' role in AS will provide an attractive therapeutic target for AS.

C1q/tumor necrosis factor-related protein-6 exerts protective effects on myocardial ischemia-reperfusion injury through the modulation of the Akt-GSK-3β-Nrf2 signaling cascade

C1q/tumor necrosis factor-related protein-6 (CTRP6) is a multifunctional protein that plays a pivotal role in diverse physiological and pathological processes. To date, whether CTRP6 has a role in myocardial ischemia-reperfusion (I/R) injury remains unexplored. This work aimed to investigate the potential role and mechanism of CTRP6 in myocardial I/R injury through in vitro and in vivo experiments. CTRP6 expression was downregulated in hypoxia/reoxygenation (H/R)-treated cardiomyocytes. The apoptosis, oxidative stress, and inflammation in the H/R-treated cardiomyocytes were markedly alleviated by CTRP6 overexpression or exacerbated by CTRP6 silencing. Notably, the overexpression of CTRP6 remarkably ameliorated the myocardial injury, infarction area, cardiac apoptosis, oxidative stress, and inflammation in mice with myocardial I/R injury in vivo. Further investigation revealed that CTRP6 overexpression enhanced the activation of Nrf2 in the H/R-treated cardiomyocytes and the myocardium tissue of mice with myocardial I/R injury. CTRP6 overexpression increased the phosphorylated level of Akt and GSK-3β, and the inhibition of Akt abolished CTRP6-overexpression-elicited Nrf2 activation in the H/R-treated cardiomyocytes. Additionally, the inhibition of Akt or Nrf2 abolished the protective effects of CTRP6 overexpression on the H/R-treated cardiomyocytes. Altogether, CTRP6 had protective effects on myocardial I/R injury via the effects on the Akt-GSK-3β-Nrf2 signaling cascade. Our work recommends CTRP6 as a novel cardioprotective target for the treatment of myocardial I/R injury.

C1QTNF6 regulated by miR-29a-3p promotes proliferation and migration in stage I lung adenocarcinoma

OBJECTIVE

C1QTNF6 has been implicated as an essential component in multiple cellular and molecular preliminary event, including inflammation, glucose metabolism, endothelial cell modulation and carcinogenesis. However, the biological process and potential mechanism of C1QTNF6 in lung adenocarcinoma (LUAD) are indefinite and remain to be elucidated. Therefore, we investigated the interaction among the traits of C1QTNF6 and LUAD pathologic process.

METHODS

RT-qPCR and western blot were conducted to determine the expression levels of C1QTNF6. RNA interference and overexpression of C1QTNF6 were constructed to identify the biological function of C1QTNF6 in cellular proliferative, migratory and invasive potentials in vitro. Dual-luciferase reporter assay was applied to identify the possible interaction between C1QTNF6 and miR-29a-3p. Moreover, RNA sequencing analysis of C1QTNF6 knockdown was performed to identify the potential regulatory pathways.

RESULTS

C1QTNF6 was upregulated in stage I LUAD tissues compared with adjacent non-cancerous tissues. Concurrently, C1QTNF6 knockdown could remarkably inhibit cell proliferation, migratory and invasive abilities, while overexpression of C1QTNF6 presented opposite results. Additionally, miR-29a-3p may serve as an upstream regulator of C1QTNF6 and reduce the expression of C1QTNF6. Subsequent experiments showed that miR-29a-3p could decrease the cell mobility and proliferation positive cell rates, as well as reduce the migratory and invasive possibilities in LUAD cells via downregulating C1QTNF6. Moreover, RNA sequencing analysis demonstrated that the cytokine-cytokine receptor interaction pathway may participate in the process of C1QTNF6 regulating tumor progression.

CONCLUSION

Our study first demonstrated that downregulation of C1QTNF6 could inhibit tumorigenesis and progression in LUAD cells negatively regulated by miR-29a-3p. These consequences could reinforce our awareness and understanding of the underlying mechanism and provide a promising therapeutic target for LUAD.

Betahistine alleviates benign paroxysmal positional vertigo (BPPV) through inducing production of multiple CTRP family members and activating the ERK1/2-AKT/PPARy pathway

BACKGROUND

Betahistine is a clinical medication for the treatment of benign paroxysmal positional vertigo (BPPV). Otolin, a secreted glycoprotein with a C-terminal globular domain homologous to the immune complement C1q, has been identified as a biomarker for BPPV. However, the role of complement C1q/TNF-related proteins (CTRPs) with a C-terminal globular domain in BPPV is unclear, so we explored the change of CTRPs in betahistine treated BPPV.

METHODS

We treated BPPV patients with Betahistine (12 mg/time, 3 times/day) for 4 weeks and observed the clinical efficacy and the expression of CTRP family members in BPPV patients. Then, we constructed a vertigo mice model of vestibular dysfunction with gentamicin (150 mg/Kg) and a BPPV model of Slc26a4^loop/loop mutant mice. Adenoviral vectors for CTRP expression vector and small interfering RNA were injected via the intratympanic injection into mice and detected the expression of CTRP family members, phosphorylation levels of ERK and AKT and the expression of PPARγ. In addition, we treated mice of vestibular dysfunction with Betahistine (10 mg/Kg) and/or ERK inhibitor of SCH772984 (12 mg/Kg) and/or and PPARγ antagonist GW9662 (1 mg/Kg) for 15 days, and evaluated the accuracy of air righting reflex, the time of contact righting reflex and the scores of head tilt and swimming behavior.

RESULTS

After treatment with Betahistine, the residual dizziness duration and the score of the evaluation were reduced, and the expression of CTRP1, 3, 6, 9 and 12 were significantly increased in BPPV patients. We also found that Betahistine improved the accuracy of air righting reflex, reduced the time of contact righting reflex and the scores of head tilt and swimming behavior in gentamicin-treated mice and Slc26a4^loop/loop mutant mice. The expression levels of CTRP1, 3, 6, 9 and 12, phosphorylation levels of ERK and AKT, and PPARγ expression were significantly increased, and the scores of head tilt and swimming behavior were decreased in vestibular dysfunction mice with overexpression of CTRPs. Silencing CTRPs has the opposite effect. SCH772984 reversed the effect of Betahistine in mice with vestibular dysfunction.

CONCLUSION

Betahistine alleviates BPPV through inducing production of multiple CTRP family members and activating the ERK1/2-AKT/PPARy pathway.

Identification of metabolites in plasma related to different biological activities of Panax ginseng and American ginseng

RATIONALE

Panax ginseng (PG) and American ginseng (AMG) are both medicinal plants of the Panax genus in the Acanthopanax family. Although PG and AMG have similar components of ginsenosides, there are many differences of their bioactivities. In this study, the biochemical mechanisms of different bioactivities of PG and AMG were explored by researching the differential metabolites in plasma after administration of each of PG and AMG.

METHODS

In order to explore the material basis of differential bioactivities, two groups of mice were administrated orally with PG and AMG, and the method of metabolomics was used to identify the differential metabolites in plasma. Then network pharmacology was used based on the differential metabolites. Afterward, the metabolite-target-pathway network of PG and AMG was constructed; thus the pathways related to different bioactivities were analyzed.

RESULTS

Through principal component analysis and orthogonal projections to latent structures discriminant analysis, there were 10 differential metabolites identified in the PG group and 8 differential metabolites identified in the AMG group. Based on network pharmacology, the differential metabolites were classified and related to differential bioactivities of PG and AMG. In the PG group, there were 6 metabolites related to aphrodisiac effect and exciting the nervous system, and 5 metabolites associated with raised blood pressure. In the AMG group, 5 metabolites were classified as having the effect of inhibiting the nervous system, and 6 metabolites were related to antihypertensive effect.

CONCLUSIONS

This study explored the material basis of the differential biological activities between PG and AMG, which is significant for the research of PG and AMG use and to promote human health.

Association Between Novel Pro- and Anti- Inflammatory Adipocytokines in Patients with Acute Coronary Syndrome

Background and aims

Novel pro- and anti-inflammatory adipocytokines affect inflammation, energy metabolism, and insulin signaling. However, their role in acute coronary syndrome (ACS) development is unclear. We evaluated the diagnostic and risk predictive value of such adipocytokines for ACS.

Methods

We enrolled 168 consecutive inpatients with suspected ACS and detected serum PLIN1, PLIN2, PLIN5, CTRP6, CTRP7, CTRP11, WISP1, FAM19A5, TNF-α, and adiponectin levels. Multivariate logistic regression analysis and Spearman's test were used to assess risk factors for ACS and correlations between serum adipocytokines and continuous variables, respectively.

Results

Serum levels of the adipocytokines differed between ACS and Non-ACS groups (p < 0.05). After adjusting for confounding factors, serum PLIN1, PLIN2, PLIN5, CTRP6, CTRP7, CTRP11, WISP1, and FAM19A5 levels were independently associated with ACS (p < 0.05). Increasing tertiles of serum PLIN1, PLIN2, CTRP7, CTRP11, and WISP1 levels increased the ACS risk, which decreased gradually with increasing PLIN5 and CTRP6 tertiles (p for trend <0.05). Serum PLIN1, PLIN5, CTRP6, CTRP7, CTRP11, WISP1, and FAM19A5 levels correlated with ACS severity.

Conclusions

PLIN1, PLIN2, CTRP7, CTRP11, and WISP1 were identified as independent ACS risk factors, whereas PLIN5, CTRP6, and FAM19A5 were independent protective factors for ACS. These serum adipocytokines are novel potential clinical biomarkers of ACS.

C1q/tumor necrosis factor related protein 6 (CTRP6) regulates the phenotypes of high glucose-induced gestational trophoblast cells via peroxisome proliferator-activated receptor gamma (PPARγ) signaling

Multiple studies have confirmed that adipokines are compactly relevant to insulin resistance and participate in the pathogenesis of gestational diabetes mellitus (GDM). This paper aimed to study the effects of C1q/tumor necrosis factor related protein (CTRP)6 on the phenotypes of trophoblast cells, covering cell proliferation, invasion and migration, and initially explore the mechanism. High glucose was used to induce trophoblast cells to establish an in vitro model. The expression levels of CTRP6 were firstly determined, and then the effects of CTRP6 knockdown on cell viability, apoptosis, migration and invasion were assessed using CCK8, TUNEL, wound healing, Transwell assays. Moreover, the role of peroxisome proliferator-activated receptor gamma (PPARγ), probable target of CTRP6, was evaluated through co-transfection with PPARγ overexpression vector. The results of the present study revealed that CTRP6 and PPARγ were both upregulated in high glucose-induced cells. And CTRP6 knockdown could significantly elevate the abilities of cell viability, migration and invasion, and avoid cell apoptosis. In addition, PPARγ overexpression was found to restrain the protective effects of CTRP6 knockdown on the above aspects, indicating CTRP6 played a role in trophoblast cells via inhibiting PPARγ expression. In conclusion, CTRP6 regulated the viability, migration and invasion of high glucose-induced gestational trophoblast cells through PPARγ signaling.

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.

Adipocyte factor CTRP6 inhibits homocysteine-induced proliferation, migration, and dedifferentiation of vascular smooth muscle cells through PPARγ/NLRP3

NLRP3 and PPARγ play important roles in the development of atherosclerosis (AS). Studies have shown that PPARγ regulates the expression of NLRP3 in vascular diseases. In addition, the adipocyte factor CTRP6 can improve the activation of PPARγ in vascular diseases. However, the regulatory relationship between CTRP6, PPARγ, and NLRP3 in AS and its underlying mechanism have not been reported. Since proliferation, migration, and dedifferentiation of vascular smooth muscle cells (VSMCs) are key events in AS, in this study, we induced proliferation, migration, and dedifferentiation of VSCMs through homocysteine (HCY) to detect the specific effects of CTRP6, PPARγ, and NLRP3. Subsequently, CTRP6 was overexpressed and the PPARγ inhibitor GW9662 and agonist rosiglitazone were administered to HCY-induced VSCMs to investigate the mechanisms. The results show that the expression of CTRP6 decreased in HCY-induced VSMCs. In addition, CTRP6 overexpression inhibited the proliferation and migration of HCY-induced VSMCs, as well as cell cycle acceleration and dedifferentiation. Overexpression of CTRP6 increased HCY-induced PPARγ expression and inhibited NLRP3 expression. The addition of GW9662 and rosiglitazone further demonstrated that overexpression of CTRP6 inhibited HCY-induced VSMC proliferation, migration, and dedifferentiation through PPARγ/NLRP3 signaling. In conclusion, CTRP6 inhibited HCY-induced proliferation, migration, and dedifferentiation of VSMCs through PPARγ/NLRP3.

C1QTNF6 regulates cell proliferation and apoptosis of NSCLC in vitro and in vivo

OBJECTIVES

Lung cancer has been reported as the leading cause of cancer-associated deaths in humans, and its incidence continues to increase in the world. A growing number of studies have shown that dysregulated genes are associated with the occurrence and poor prognosis of a variety of tumors, including non-small cell lung cancer (NSCLC). C1q/tumor necrosis factor-related protein 6 (C1QTNF6), a member of the C1q/tumor necrosis factor-related protein (CTRP) family, has been revealed to play a role in carcinogenesis and cancer progression. Nevertheless, the effects and mechanisms of C1QTNF6 in NSCLC remain unrevealed.

MATERIALS AND METHODS

MTT (3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide) and colony formation, flow cytometric and transwell assays were performed to explore the cell function. Real-time PCR (RT-PCR) and Western blot were used to analyze the mRNA and protein expression.

RESULTS

In the present study, we found that C1QTNF6 significantly promoted the proliferation of SPCA1 and A549 cells by MTT and colony formation assays. In addition, down-regulation of C1QTNF6 weakened the tumor growth in vivo. Besides, C1QTNF6 remarkably reduced apoptosis by flow cytometric analysis and TUNEL assay. Furthermore, the capability of migration and invasion was obviously enhanced on C1QTNF6 overexpression.

CONCLUSION

Overall, our results demonstrated that inhibition of C1QTNF6 attenuated cell proliferation, migration, invasion and promoted apoptosis in vitro and in vivo of NSCLC. Based on the above results, our study provided us with a new and key perspective in understanding and treating NSCLC.

C1q/tumor necrosis factor-related protein-6 attenuates TNF-α-induced apoptosis in salivary acinar cells via AMPK/SIRT1-modulated miR-34a-5p expression

C1q/tumor necrosis factor-related protein-6 (CTRP6) is a newly identified adipokine involved in diverse biological processes. However, its role in salivary glands remains unknown. Here, we demonstrated that CTRP6 was mainly distributed in the nuclei, apicolateral membranes, and cytoplasm of human submandibular glands (SMGs), serous cells of parotid glands, and ducts and apicolateral membranes of serous cells in rats and mice. CTRP6 inhibited the apoptosis rate and reversed the increased levels of cleaved caspase 3, caspase 8, caspase 9, and cytochrome C and the decreased Bcl-2 expression induced by tumor necrosis factor (TNF)-α in both SMG-C6 cells and cultured human SMG tissues. Microarray analysis identified 43 differentially expressed microRNAs (miRNAs) in the SMGs of nonobese diabetic mice. miR-34a-5p was selected due to its upregulation by TNF-α, which was abolished by CTRP6. The miR-34a-5p inhibitor promoted whereas the miR-34a-5p mimic suppressed the effects of CTRP6 on TNF-α-induced apoptosis. CTRP6 increased AMP-activated protein kinase (AMPK) phosphorylation and reversed TNF-α-induced SIRT1 downregulation in salivary cells. AraA, an AMPK inhibitor, reversed the effects of CTRP6 on TNF-α-induced alterations in the levels of SIRT1, miR-34a-5p, Bcl-2, and cleaved caspase 3 in vitro and ex vivo, whereas activating AMPK by AICAR reversed the decrease in SIRT1 expression and increase in miR-34a-5p expression induced by TNF-α. Inhibition of SIRT1 by EX527 suppressed the effects of CTRP6 on TNF-α-induced changes in miR-34a-5p and apoptosis-related proteins. Our findings indicate that salivary glands are novel sites for CTRP6 synthesis and secretion. CTRP6 protects acinar cells against TNF-α-induced apoptosis via AMPK/SIRT1-modulated miR-34a-5p expression.

Impact of the Renin-Angiotensin System on the Endothelium in Vascular Dementia: Unresolved Issues and Future Perspectives

The effects of the renin-angiotensin system (RAS) surpass the renal and cardiovascular systems to encompass other body tissues and organs, including the brain. Angiotensin II (Ang II), the most potent mediator of RAS in the brain, contributes to vascular dementia via different mechanisms, including neuronal homeostasis disruption, vascular remodeling, and endothelial dysfunction caused by increased inflammation and oxidative stress. Other RAS components of emerging significance at the level of the blood-brain barrier include angiotensin-converting enzyme 2 (ACE2), Ang(1-7), and the AT2, Mas, and AT4 receptors. The various angiotensin hormones perform complex actions on brain endothelial cells and pericytes through specific receptors that have either detrimental or beneficial actions. Increasing evidence indicates that the ACE2/Ang(1-7)/Mas axis constitutes a protective arm of RAS on the blood-brain barrier. This review provides an update of studies assessing the different effects of angiotensins on cerebral endothelial cells. The involved signaling pathways are presented and help highlight the potential pharmacological targets for the management of cognitive and behavioral dysfunctions associated with vascular dementia.

Protective effect of CTRP6 on cerebral ischemia/reperfusion injury by attenuating inflammation, oxidative stress and apoptosis in PC12 cells

The newly identified C1q/tumor necrosis factor (TNF)-related protein-6 (CTRP6) is a highly conserved paralog of adiponectin with modulatory effects on metabolism and inflammation. However, the role of CTRP6 in cerebral ischemia/reperfusion (I/R) injury remains unknown. The aim of the present study was to explore the protective effects of CTRP6 against cerebral I/R injury and elucidate the possible underlying mechanisms. Oxygen-glucose deprivation and reperfusion (OGD/R) was used to induce an I/R injury model in vitro. Western blotting, reverse transcription-quantitative PCR, ELISA and flow cytometry analysis were used to measure the levels of CTRP6 along with those of inflammation-, oxidative stress- and apoptosis-related cytokines. The results indicated that CTRP6 expression was markedly downregulated following OGD/R. OGD/R also increased i) the activities of pro-inflammatory factors TNF-α, interleukin (IL)-1β, IL-6 and the levels of the oxidative products reactive oxygen species and malondialdehyde; ii) the ratio of apoptotic PC12 cells and iii) the expression of the pro-apoptotic proteins Bax, cleaved caspase-3 and cleaved caspase-9. In addition, the activities of the anti-inflammatory factors IL-10 and superoxide dismutase and the expression of the anti-apoptotic protein Bcl-2 were decreased. However, overexpression of CTRP6 rescued OGD/R-stimulated exacerbation of inflammation, oxidative stress and apoptosis. Mechanistically, OGD/R activated Ras homolog family member A (RhoA)/Rho-associated coiled-coil-containing protein kinase (Rock)/phosphatase and tensin homologue deleted on chromosome 10 (PTEN) signaling, whereas CTRP6 overexpression restored the expression of RhoA, Rock, PTEN, phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt). Furthermore, when CTRP6 and RhoA were overexpressed at the same time, RhoA abolished the protective effects of CTRP6 overexpression on OGD/R-induced inflammation, oxidative stress and apoptosis, while the presence of a PTEN inhibitor recovered the protective effects of CTRP6. Taken together, the findings of the present study indicate that CTRP6 attenuates cerebral ischemia/reperfusion-induced inflammation, oxidative stress and apoptosis via inhibiting the RhoA/Rock/PTEN pathway, thereby activating PI3K/Akt signaling.

Circulating levels of C1q/TNF-α-related protein 6 (CTRP6) in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders affecting females of reproductive age. It has been associated with cardiometabolic disorders including diabetes mellitus and cardiovascular disorders, and increases the risk of developing fecundity pathologies including recurrent pregnancy loss (RPL) and infertility. C1q/tumor necrosis factor-α-related protein-6 (CTRP6) is a novel adipokine involved in glucose and lipid metabolism, host inflammation, and organogenesis. In the present study, we aimed to determine the association of serum CTRP6 levels with some components of metabolic syndrome in PCOS patients (infertile PCOS [inf-PCOS] and PCOS-RPL). This case-control study included 120 PCOS patients (60 inf-PCOS and 60 PCOS-RPL) and 60 healthy controls. Serum high-sensitivity C-reactive protein (hs-CRP) and homocysteine were measured using commercial kits, while adiponectin and CTRP6 levels were assessed using ELISA technique. Inf-PCOS and PCOS-RPL individuals had higher levels of serum CTRP6 than controls (546.15 ± 125.02 ng/ml and 534.04 ± 144.19 ng/ml vs. 440.16 ± 159.24 ng/ml; both p < .001). Moreover, serum adiponectin levels were significantly reduced, while fasting insulin, homeostasis model assessment of insulin resistance, free testosterone, and hs-CRP levels were significantly elevated in PCOS group, when compared with controls. Furthermore, serum CTRP6 positively associated with body mass index in all subjects. It showed an inverse correlation with adiponectin in PCOS group and subgroups. However, it had a direct association with hs-CRP in PCOS group and inf-PCOS subgroup, but not PCOS-RPL subgroup. These findings unravel a probable role of CTRP6 in PCOS pathogenesis, which poses a possibility to be a good diagnostic target. However, further investigation is needed.

MiR-29b-3p promotes particulate matter-induced inflammatory responses by regulating the C1QTNF6/AMPK pathway

Inflammatory responses are considered to be the critical mechanism underlying particulate matter (PM)-induced development and exacerbation of chronic respiratory diseases. MiR-29b-3p has been found to participate in various biological processes, but its role in PM-induced inflammatory responses was previously unknown. Here, we constructed a miRNA PCR array to find that miR-29b-3p was the most highly expressed in human bronchial epithelial cells (HBECs) exposed to PM. MiR-29b-3p promoted PM-induced pro-inflammatory cytokines (IL-1β, IL-6, and IL-8) expression via inhibiting the AMPK signaling pathway in HBECs. RNA sequencing and luciferase reporter assay identified that miR-29b-3p targeted complement C1q tumor necrosis factor-related protein 6 (C1QTNF6), a protein that protected from PM-induced inflammatory responses via activating the AMPK signaling pathway. In vivo, miR-29b-3p antagomirs delivered via the tail vein prior to PM exposure significantly counteracted PM-induced miR-29b-3p upregulation and C1QTNF6 downregulation in lung tissues. Furthermore, miR-29b-3p inhibition alleviated inflammatory cells infiltration and pro-inflammatory cytokines secretion in the lung of PM-exposed mice. These findings firstly revealed that miR-29b-3p acted as a novel modulator of PM-induced inflammatory responses by targeting the C1QTNF6/AMPK signaling pathway, which contributes to a better understanding of the biological mechanisms underlying adverse PM-induced respiratory health effects.

Circulating CTRP6 Levels are Increased in Overweight or Obese Chinese Individuals and Associated with Insulin Resistance Parameters: A Pilot Study

AIMS

CTRP6, a newly discovered adipokine, has been found to be a regulator for energy homeostasis. However, the association between circulating CTRP6 and obesity in humans is still unclear.

METHODS

256 individuals, including 185 overweight/obese (OW/OB) and 71 normal weight adults, were recruited for this study. Circulating concentrations of CTRP6 and adiponectin (Adipoq) were examined by ELISA.

RESULTS

Serum CTRP6 levels in obese individuals were significantly increased compared with those in healthy individuals (506.1±134.9 vs.363.3±80.5 ng/mL, P<0.01). Conversely, serum Adipoq concentrations in OW/OB individuals were markedly decreased compared with healthy controls [20.8 (12.1-29.3) vs. 14.1 ⁽ 8.61-17.7) ^; P<0.01]. Correlation analysis revealed that there was a positive relationship between circulating CTRP6 and age, BMI, Fat%, LDL-C, TG, WHR, TC, FBG, FIns, HOMA-IR and HbA1c, but there was an inverse correlation with Adipoq and HDL-C. Logistic regression analysis revealed that high serum CTRP6 levels are markedly associated with OW/OB. Finally, ROC curve analysis showed that the cut-off value for serum CTRP6 for prediction of IR is 518 ng/mL.

CONCLUSIONS

CTRP6 may be a marker related to OW/OB.

Silencing of GPR82 with Interference RNA Improved Metabolic Profiles in Rats with High Fructose Intake

Metabolic syndrome (MS) is a clinical condition, constituted by alterations that lead to the onset of type II diabetes and cardiovascular disease. It has been reported that orphan G-protein-coupled receptor 82 (GPR82) participates in metabolic processes. The aim of this study was to evaluate the function of GPR82 in MS using a small interfering RNA (siRNA) against this receptor. We used Wistar rats of 10-12 weeks of age fed with a high-fructose solution (70%) for 9 weeks to induce MS. Subsequently, the rats were treated with an intrajugular dose of an siRNA against GPR82 and the effects were evaluated on day 3 and 7 after administration. On day 3 the siRNA had a transient effect on decreasing blood pressure and triglycerides and increasing high-density lipoprotein cholesterol, which recovered to the MS control on day 7. Decreased gene expressions of GPR82 mRNA in the aorta and heart were observed on day 3; moreover, decreased gene expression was maintained in the aorta on day 7. Therefore, we conclude that the orphan receptor GPR82 participates in the development of MS induced by fructose and the silencing of this receptor could ameliorate metabolic components.

C1qTNF-related protein-6 protects against doxorubicin-induced cardiac injury

The clinical use of doxorubicin (DOX) is limited by its toxic effect. However, there is no specific drug that can prevent DOX-related cardiac injury. C1qTNF-related protein-6 (CTRP6) is a newly identified adiponectin paralog with many protective functions on metabolism and cardiovascular diseases. However, little is known about the effect of CTRP6 on DOX-induced cardiac injury. The present study aimed to investigate whether CTRP6 could protect against DOX-related cardiotoxicity. To induce acute cardiotoxicity, the mice were intraperitoneally injected with a single dose of DOX (15 mg/kg). Cardiomyocyte-specific CTRP6 overexpression was achieved using an adenoassociated virus system at 4 weeks before DOX injection. The data in our study demonstrated that CTRP6 messenger RNA and protein expression were decreased in DOX-treated hearts. CTRP6 attenuated cardiac atrophy induced by DOX injection and inhibited cardiac apoptosis and improved cardiac function in vivo. CTRP6 also promoted the activation of protein kinase B (AKT/PKB) signaling pathway in DOX-treated mice. CTRP6 prevented cardiomyocytes from DOX-induced apoptosis and activated the AKT pathway in vitro. CTRP6 lost its protection against DOX-induced cardiac injury in mice with AKT inhibition. In conclusion, CTRP6 protected the heart from DOX-cardiotoxicity and improves cardiac function via activation of the AKT signaling pathway.

C1q/TNF-related protein-6 is associated with insulin resistance and the development of diabetes in Chinese population

AIMS

C1q/tumor necrosis factor-related protein-6 (CTRP6) is a novel adipokine and has emerged as an important mediator for lipid and glucose metabolism. However, to date, the relationship between CTRP6 and T2DM in humans has not been demonstrated. Our objective is to investigate the association of circulating CTRP6 with T2DM in a cross-sectional study.

METHODS

118 patients with newly diagnosed T2DM, 98 subjects with impaired glucose tolerant (IGT) and 132 healthy subjects were recruited for this study. OGTT were performed in 48 healthy individuals to investigate the association of CTRP6 with glucose, insulin and other adipokines. Circulating CTRP6, TNF-α and Adipoq were measured by ELISA.

RESULTS

IGT and T2DM individuals had higher serum CTRP6 levels than healthy controls (406.2 ± 136.6 and 539.1 ± 169.7 vs. 354.3 ± 117.2 ng/mL; both P < 0.01), whereas serum CTRP6 concentrations were further increased in T2DM patients compared with IGT individuals (P < 0.01). Serum CTRP6 levels were found to be related positively to BMI, WHR, FAT%, TC, TG, HbA1c, FBG, 2 h-OGTT, fasting insulin (FIns), 2 h-Ins, HOMA-IR and TNF-α, and negatively with HDL-C and Adipoq in all individuals (P < 0.05 or P < 0.01). Multivariate logistic regression analysis demonstrated that CTRP6 was correlated with both IGT and T2DM. After an oral glucose challenge, serum CTRP6 concentrations exhibited a similar change with blood glucose, insulin, TNF-α and Adipoq.

CONCLUSIONS

CTRP6 may be a metabolism- and nutrition-related adipokine and may be related to insulin resistance and T2DM.

TRIAL REGISTRATIONS

Clinical Trial Registration Number: ChiCTR-OCC-11001422. Registration name: Plasma cytokines and endothelial function in type 2 diabetes.

CTRP6 inhibits PDGF-BB-induced vascular smooth muscle cell proliferation and migration

Vascular smooth muscle cell (VSMC) proliferation and migration play critical roles in the development and progression of atherosclerosis. C1q/tumor necrosis factor-related protein 6 (CTRP6), a member of CTRPs family, was involved in cardiovascular diseases, inflammatory reaction and adipogenesis. However, the role of CTRP6 in VSMCs remains largely unknown. The purpose of this study is to investigate the effects of CTRP6 on VSMC proliferation and migration and explore the possible mechanism. Our results indicated that CTRP6 expression was dramatically down-regulated in human atherosclerotic tissues and in cultured VSMCs stimulated by platelet-derived growth factor-BB (PDGF-BB). In addition, CTRP6 overexpression significantly inhibited the proliferation and migration of VSMCs exposed to PDGF-BB, as well as increased expression of α-SMA and SM22α in PDGF-BB-stimulated VSMCs. Furthermore, CTRP6 overexpression efficiently prevented the activation of PI3K/Akt/mTOR in VSMCs in response to PDGF-BB. In conclusion, these findings showed that CTRP6 inhibits PDGF-BB-induced VSMC proliferation and migration, at least in part, through suppressing the PI3K/Akt/mTOR signaling pathway. Therefore, CTRP6 may be a potential target for the treatment of atherosclerosis.