The correlation between two potentially antagonistic human adipocytokines, WISP-1 and CTRP1, and their association with insulin resistance

INTRODUCTION AND OBJECTIVE

Wnt-1 signaling pathway protein 1 (WISP-1) and complement-C1q TNF-related protein 1 (CTRP1) are adipokines with possible opposite effects in regulating insulin sensitivity. The study investigated the correlation between circulating WISP-1 and CTRP1 in non-diabetic patients. Correlations between adipokines concentrations and biochemical and anthropometric parameters were also studied.

MATERIAL AND METHODS

The cross-sectional study enrolled 107 adult patients without diabetes. Patients with obesity accounted for 52.3% of the study group. Clinical, anthropometric, and laboratory data, including serum levels of WISP-1 and CTRP1, were obtained.

RESULTS

The moderate positive correlation between serum WISP-1 and CTRP1 concentrations was observed (p<0.000001, r=0.49). The correlation was more substantial in non-obese patients than in the obese group (r=0.66 and r=0.36, respectively; p<0.01). Circulating CTRP1 correlated positively with fasting insulin, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), total cholesterol, HDL cholesterol, and LDL cholesterol (p<0.05). WISP-1 level correlated with total cholesterol and HDL cholesterol concentrations (p<0.05). There was no significant difference in WISP-1 and CTRP1 concentrations between the groups with and without insulin resistance. The concentrations of WISP-1 and CTRP1 were significantly higher in females than in males (p<0.05).

CONCLUSIONS

WISP-1 and CTRP1 may represent interrelated factors that antagonistically affect insulin resistance.

C1q/TNF-Related Proteins 1, 6 and 8 Are Involved in Corneal Epithelial Wound Closure by Targeting Relaxin Receptor RXFP1 In Vitro

Inadequate wound healing of ocular surface injuries can lead to permanent visual impairment. The relaxin ligand-receptor system has been demonstrated to promote corneal wound healing through increased cell migration and modulation of extracellular matrix formation. Recently, C1q/tumor necrosis factor-related protein (CTRP) 8 was identified as a novel interaction partner of relaxin receptor RXFP1. Additional data also suggest a role for CTRP1 and CTRP6 in RXFP1-mediated cAMP signaling. However, the role of CTRP1, CTRP6 and CTRP8 at the ocular surface remains unclear. In this study, we investigated the effects of CTRP1, CTRP6, and CTRP8 on epithelial ocular surface wound closure and their dependence on the RXFP1 receptor pathway. CTRP1, CTRP6, and CTRP8 expression was analyzed by RT-PCR and immunohistochemistry in human tissues and cell lines derived from the ocular surface and lacrimal apparatus. In vitro ocular surface wound modeling was performed using scratch assays. We analyzed the effects of recombinant CTRP1, CTRP6, and CTRP8 on cell proliferation and migration in human corneal and conjunctival epithelial cell lines. Dependence on RXFP1 signaling was established by inhibiting ligand binding to RXFP1 using a specific anti-RXFP1 antibody. We detected the expression of CTRP1, CTRP6, and CTRP8 in human tissue samples of the cornea, conjunctiva, meibomian gland, efferent tear ducts, and lacrimal gland, as well as in human corneal, conjunctival, and meibomian gland epithelial cell lines. Scratch assays revealed a dose-dependent increase in the closure rate of surface defects in human corneal epithelial cells after treatment with CTRP1, CTRP6, and CTRP8, but not in conjunctival epithelial cells. Inhibition of RXFP1 fully attenuated the effect of CTRP8 on the closure rate of surface defects in human corneal epithelial cells, whereas the CTRP1 and CTRP6 effects were not completely suppressed. Conclusions: Our findings demonstrate a novel role for CTRP1, CTRP6, and CTRP8 in corneal epithelial wound closure and suggest an involvement of the relaxin receptor RXFP1 signaling pathway. This could be a first step toward new approaches for pharmacological and therapeutic intervention.

CTRP1: A novel player in cardiovascular and metabolic diseases

Cardiovascular diseases (CVDs) are a series of diseases induced by inflammation and lipid metabolism disorders, among others. Metabolic diseases can cause inflammation and abnormal lipid metabolism. C1q/TNF-related proteins 1 (CTRP1) is a paralog of adiponectin that belongs to the CTRP subfamily. CTRP1 is expressed and secreted in adipocytes, macrophages, cardiomyocytes, and other cells. It promotes lipid and glucose metabolism but has bidirectional effects on the regulation of inflammation. Inflammation can also inversely stimulate CTRP1 production. A vicious circle may exist between the two. This article introduces CTRP1 from the structure, expression, and different roles of CTRP1 in CVDs and metabolic diseases, to summarize the role of CTRP1 pleiotropy. Moreover, the proteins which may interact with CTRP1 are predicted through GeneCards and STRING, speculating their effects, to provide new ideas for the study of CTRP1.

CTRP1 Aggravates Cardiac Fibrosis by Regulating The NOX2/P38 Pathway in Macrophages

OBJECTIVE

C1q/TNF-related proteins 1 (CTRP1) is a recently identified adiponectin associated with obesity-linked disorders and adverse cardiovascular events. The effect of CTRP1 on cardiac fibrosis has not yet been fully elucidated; thus, we aimed to explore this association.

MATERIALS AND METHODS

In this experimental study, a mouse model of cardiac fibrosis was established by administering isoproterenol (ISO) (subcutaneously injecting 10 mg/kg/day for 3 days and then 5 mg/kg/day for 11 days). Mice were also injected with recombinant CTRP1 protein (200 μg/kg) 14 days after the final ISO administration. Adult mouse fibroblasts were isolated and stimulated with transforming growth factor (TGF) β1, followed by treatment with recombinant CTRP1. Primary bone marrow-derived macrophages were isolated from C57BL/6J mice and treated with recombinant CTRP1 as well.

RESULTS

CTRP1 level was increased in mouse plasma and heart tissue 2 weeks after ISO injection. Our findings indicated that recombinant CTRP1 injection aggravated ISO-induced cardiac fibrosis and dysfunction. However, recombinant CTRP1 did not alter TGFβ1-induced fibroblast proliferation and activation or collagen transcription. Recombinant CTRP1 exacerbated ISO-induced macrophage infiltration and inflammatory response. We determined that macrophages treated with recombinant CTRP1 showed increased pro-inflammatory cytokine release. Fibroblasts co-cultured with macrophages treated with recombinant CTRP1 showed increased proliferation and collagen transcription. We also found that CTRP1 upregulated the NADPH oxidase 2 (NOX2)/p38 pathway in macrophages. When we inhibited p38 signaling, the pro-inflammatory effect of CTRP1 on macrophages was counteracted. Fibroblasts co-cultured with macrophages treated with a p38 inhibitor also showed limited proliferation and collagen transcription.

CONCLUSION

Cardiac fibrosis was aggravated with the activation of the NOX2/p38 pathway in macrophages after CTRP1 treatment.

CTRP1 prevents high fat diet-induced obesity and improves glucose homeostasis in obese and STZ-induced diabetic mice

BACKGROUND

C1q/tumor necrosis factor-related protein 1 (CTRP1) is an adipokine secreted by adipose tissue, related to chondrocyte proliferation, inflammation, and glucose homeostasis. However, the therapeutic effects on metabolic disorders and the underlying mechanism were unclear. Here, we investigated the functions and mechanisms of CTRP1 in treating obesity and diabetes.

METHODS

The plasmid containing human CTRP1 was delivered to mice by hydrodynamic injection, which sustained expression of CTRP1 in the liver and high protein level in the blood. High-fat diet (HFD) fed mice and STZ-induced diabetes model were used to study the effects of CTRP1 on obesity, glucose homeostasis, insulin resistance, and hepatic lipid accumulation. The lipid accumulation in liver and adipose tissue, glucose tolerance, insulin sensitivity, food intake, and energy expenditure were detected by H&E staining, Oil-Red O staining, glucose tolerance test, insulin tolerance test, and metabolic cage, respectively. The metabolic-related genes and signal pathways were determined using qPCR and western blotting.

RESULTS

With high blood circulation, CTRP1 prevented obesity, hyperglycemia, insulin resistance, and fatty liver in HFD-fed mice. CTRP1 also improved glucose metabolism and insulin resistance in obese and STZ-induced diabetic mice. The metabolic cage study revealed that CTRP1 reduced food intake and enhanced energy expenditure. The mechanistic study demonstrated that CTRP1 upregulated the protein level of leptin in blood, thermogenic gene expression in brown adipose tissue, and the gene expression responsible for lipolysis and glycolysis in white adipose tissue (WAT). CTRP1 also downregulated the expression of inflammatory genes in WAT. Overexpression of CTRP1 activated AMPK and PI3K/Akt signaling pathways and inhibited ERK signaling pathway.

CONCLUSION

These results demonstrate that CTRP1 could improve glucose homeostasis and prevent HFD-induced obesity and fatty liver through upregulating the energy expenditure and reducing food intake, suggesting CTRP1 may serve as a promising target for treating metabolic diseases.

CTRP1 Knockout Attenuates Tumor Progression in A549 and HCT116 Cancer Cells

Simple Summary

CTRP1 belongs to the C1q and TNF-related protein family, and we generated CTRP1 knockout cells to examine the role of CTRP1 in tumor progression. CTRP1 knockout attenuates cell growth, invasion and tumor growth in mice, suggesting that CTRP1 expression promotes tumor progression.

Abstract

C1q and TNF-related 1 (C1QTNF1/CTRP1) is an adiponectin-associated protein belonging to the C1q/TNF-related protein family. Recent studies have shown that the C1q and TNF-related protein (CTRP) family is involved in cancer progression; however, the specific role of CTRP1 in tumor progression has not yet been elucidated. To examine the role of CTRP1 in tumor progression, we generated CTRP1 knockout A549 and HCT116 cell lines, which reduced the expression levels of nuclear factor (NF)-κB-dependent and metastasis-promoting transcripts. We demonstrated that CTRP1 knockout inhibited the cell proliferation and invasion and tumor growth. Finally, database analysis showed that CTRP1 expression was upregulated in metastatic cancers and elevated levels of CTRP1 were associated with poor prognosis. These results suggest that CTRP1 expression contributes to NF-κB signaling and promotes tumor progression.

CTRP1 Attenuates Cerebral Ischemia/Reperfusion Injury via the PERK Signaling Pathway

Cerebral ischemic stroke is one of the leading causes of death worldwide. Previous studies have shown that circulating levels of CTRP1 are upregulated in patients with acute ischemic stroke. However, the function of CTRP1 in neurons remains unclear. The purpose of this study was to explore the role of CTRP1 in cerebral ischemia reperfusion injury (CIRI) and to elucidate the underlying mechanism. Middle cerebral artery occlusion/reperfusion (MCAO/R) and oxygen-glucose deprivation/reoxygenation (OGD/R) models were used to simulate cerebral ischemic stroke in vivo and in vitro, respectively. CTRP1 overexpression lentivirus and CTRP1 siRNA were used to observe the effect of CTRP1 expression, and the PERK selective activator CCT020312 was used to activate the PERK signaling pathway. We found the decreased expression of CTRP1 in the cortex of MCAO/R-treated rats and OGD/R-treated primary cortical neurons. CTRP1 overexpression attenuated CIRI, accompanied by the reduction of apoptosis and suppression of the PERK signaling pathway. Interference with CTRP1 expression in vitro aggravated apoptotic activity and increased the expression of proteins involved in the PERK signaling pathway. Moreover, activating the PERK signaling pathway abolished the protective effects of CTRP1 on neuron injury induced by CIRI in vivo and in vitro. In conclusion, CTRP1 protects against CIRI by reducing apoptosis and endoplasmic reticulum stress (ERS) through inhibiting the PERK-dependent signaling pathway, suggesting that CTRP1 plays a crucial role in the pathogenesis of CIRI.

CTRP1 decreases ABCA1 expression and promotes lipid accumulation through the miR-424-5p/FoxO1 pathway in THP-1 macrophage-derived foam cells

Prevention of ATP binding cassette transporter A1 (ABCA1)-dependent cholesterol efflux leads to lipid accumulation in macrophages and atherosclerosis development. C1q tumor necrosis factor-related protein 1 (CTRP1), a conserved paralog of adiponectin, has been shown to aggravate atherosclerosis via its proinflammatory property. However, very little is known about its effects on ABCA1 expression and macrophage lipid accumulation. In the current studies, we found that CTRP1 downregulated ABCA1 expression, inhibited cholesterol efflux to apoA-I and promoted lipid accumulation in THP-1 macrophage-derived foam cells. Forkhead box O1 (FoxO1), a transcriptional repressor of ABCA1, was identified as a direct target of miR-424-5p. Mechanistically, CTRP1 attenuated miR-424-5p levels and then augmented FoxO1 expression in the nucleus, which led to downregulation of ABCA1 expression and inhibition of cholesterol efflux. In conclusion, these findings suggest that CTRP1 restrains cholesterol efflux and facilitates macrophage lipid accumulation through the miR-424-5p/FoxO1/ABCA1 signaling pathway, thereby providing a novel mechanistical insight into its proatherosclerotic action.

Elevated Levels of CTRP1 in Obesity Contribute to Tumor Progression in a p53-Dependent Manner

Simple Summary

Obesity is regarded as a risk factor for various cancers. However, the molecular mechanisms linking obesity with cancer remain primarily uncharacterized. In this study, we demonstrate that CTRP1, an adiponectin paralogue, promotes tumor growth in a p53-dependent manner. Obese mice on a high-fat diet showed a higher level of CTRP1 protein in serum. It is also known that CTRP1 treatment contributes to tumor growth and cell migration. These results indicate that an elevated level of CTRP1 in obesity promotes tumor progression.

Abstract

Mounting evidence supports the relationship between obesity and cancer. However, the molecular mechanisms linking obesity with cancer remain largely uninvestigated. In this study, we demonstrate that the expression of C1q/TNF-related protein 1 (CTRP1), an adiponectin paralogue, contributes to tumor growth by regulating the tumor suppressor p53. In our study, obese mice on a high-fat diet showed higher serum CTRP1 levels. Through in vitro experiments, we showed that the secreted form of CTRP1 in the culture medium decreased p53 expression and p53-dependent transcription in the cells. Moreover, CTRP1 treatment enhanced colony formation and cell migration. These results collectively suggest that elevated levels of CTRP1 in obesity significantly contribute to tumor progression.

CTRP1 Aggravates Cardiac Dysfunction Post Myocardial Infarction by Modulating TLR4 in Macrophages

CTRP1 (C1q/TNF-α [tumour necrosis factor-α]-related protein 1), an adiponectin paralog, is associated with diabetes and adverse events in cardiovascular disease. However, its effect on cardiac function post myocardial infarction (MI) is unclear. Our study aimed to explore the role of CTRP1 in cardiac function post MI. CTRP1 global knockout mice were subjected to left anterior descending ligation to establish the MI model. C57BL6J mice were also administered recombinant CTRP1 protein (200 μg/kg) 7 days post MI. As a result, mice with CTRP1 deficiency exhibited an increased survival rate, a reduced infarct area, improved cardiac function and decreased inflammation and oxidative stress levels at 4 weeks post MI compared with those of mice receiving the CRTP1 injection, whose conditions deteriorated. However, cardiomyocytes with either CTRP1 silencing or CTRP1 treatment showed few differences in inflammation and oxidative stress levels compared with those of the control under hypoxic conditions. The activation of macrophages isolated from CTRP1-deficient mice was decreased in response to interferon-γ, while CTRP1 enhanced the activation of macrophages in response to interferon-γ. Macrophage scavengers and clodronate liposomes antagonized the effects of CTRP1 injection in mice. We also found that CTRP1 regulated macrophage activation via adiponectin receptor 1, which binds to TLR4 on the macrophage membrane. TLR4 knockout also antagonized the effects of the CTRP1 protein on mice with MI. Taken together, these data indicate that CTRP1 supresses cardiac function post MI via TLR4 on macrophages. Targeting CTRP1 may become a promising therapeutic approach to cardiac dysfunction post MI.

The circulating levels of CTRP1 and CTRP5 are associated with obesity indices and carotid intima-media thickness (cIMT) value in patients with type 2 diabetes: a preliminary study

BACKGROUND

There is growing evidence that the C1qTNF-related protein (CTRP) family has a crucial role in the pathophysiology of metabolic disorders such as type 2 diabetes (T2D) and obesity. We sought to identify the association of CTRP1 and CTRP5 circulating levels with various obesity parameters such as visceral adipose tissue (VAT) thickness, visceral adiposity index (VAI), and with carotid intima-media thickness (cIMT) in patients with T2D and controls.

METHODS

This preliminary study consisted of men with T2D (n = 42) and men without T2D (n = 42). The measurement of cIMT and VAT thickness was performed using an Accuvix XQ ultrasound. Circulating levels of CTRP1, CTRP5, and adiponectin were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

CTRP-1 and CTRP1/CTRP5 ratio were markedly higher in patients with T2D compared to controls (p < 0001 and p = 0004 respectively). Interestingly, binominal logistic regression revealed that a higher circulating level of CTRP1 was associated with the presence of T2D (odds ratio [OR]: 1.009 [95% CI: 1.004-1.015]; P = .001). CTRP1 circulating levels were correlated with WHR, VAT, and HOMA-IR in the whole population study. Also, we observed that the ratio of CTRP1 to CTRP5 in plasma (β = 0.648, P = 0.005) and CTRP5 circulating levels (β = 0.444, P = 0.049) are independently associated with cIMT value.

CONCLUSIONS

Our results indicated that CTRP1 and CTRP5 concentrations were correlated with atherosclerosis in men with T2D and these adipokines might have a causal role for cardiometabolic risk in T2D.However, more studies in large sample sizes are required to clarify the role of CTRPs in T2D pathogenesis.

Assessing the blood concentration of new adipocytokines in patients with ischaemic stroke

INTRODUCTION

Ischaemic stroke (IS) is a disease that is a common cause of death and one of the most common causes of disability in adults. There is a continuous need to conduct stroke pathogenesis studies. A certain role here can be attributed to adipose-derived hormones. The aim of this paper is to assess the blood concentration for selected adipocytokines: omentin-1, irisin, protein-1 related with C1q/TNF (CTRP1), vaspin and nesfatin-1 in IS patients, and an attempt to define their role as risk factors for ischaemic stroke.

MATERIAL AND METHODS

The study included 46 patients with ischaemic stroke (27 females, 19 males, average 67.6 years of age). The control group consisted of 32 patients (16 females, 16 males, average 64.1 years of age) who had never had cerebrovascular diseases.

RESULTS

The concentration of omentin-1 and CTRP1 in the group of stroke patients was higher than in the control group, whereas the concentrations of nesfatin-1 and irisin was significantly lower than in the control group. The vaspin level was similar in both groups of patients. Statistical analysis using logistic regression allows us to find that CTRP1 can be a significant stroke risk factor. A statistically significant positive correlation was found between the concentration of CTRP1 and NIHSS. However, no correlation between the concentration of other adipocytokines under investigation and the severity of ischaemic stroke was found.

CONCLUSIONS

From among the adipocytokines under investigation, higher concentrations of omentin-1 and CTRP1 and lower blood concentrations of nesfatin-1, irisin significantly increase the odds of getting to the group of ischaemic patients. It seems that CTRP1 can be an independent predictive factor of IS.

CTRP1 prevents sepsis-induced cardiomyopathy via Sirt1-dependent pathways

C1q/tumor necrosis factor-related protein 1 (CTRP1) has recently been identified as a key regulator of cardio-metabolic diseases. It has been reported that CTRP1 could inhibit the hypertrophic response in mice. However, the effect of CTRP1 on sepsis-induced cardiomyopathy remains completely unknown. Cardiomyocyte-specific CTRP1 overexpression was achieved using an adeno associated virus system in mice. CTRP1 deficiency mice were also subjected to lipopolysaccharide (LPS) injection. We found that CTRP1 overexpression improved survival rate and cardiac function, and suppressed myocardial inflammation, oxidative damage and apoptosis without affecting metabolic disturbance in LPS-treated mice. CTRP1 depletion further decreased survival rate and cardiac function, and promoting myocardial inflammation, oxidative damage and apoptosis in sepsis mice. In addition, we showed that CTRP1 provided protection against LPS-induced cell injury in vitro. CTRP1 activated sirtuin 1 (Sirt1) signaling pathway, and Sirt1 inhibition or deficiency blocked CTRP1-mediated cardioprotective effects in vivo and in vitro. More importantly, our study found that recombinant human globular domain of CTRP1 infusion was also capable of blocking sepsis-induced cardiomyopathy in mice. In conclusion, CTRP1 improved survival rate and attenuated LPS-induced cardiac injury via activating Sirt1 signaling pathway.

Data on the association between CTRP1 and future major adverse cardiovascular events in patients undergoing coronary angiography

This article provides additional data on the association of the new adipokine CTRP1 with the incidence of future major adverse cardiovascular events in a prospective cohort of patients undergoing coronary angiography. In this regard, multivariable Cox proportional hazards models taking into account cardiac risk markers are presented. Additionally, data on the impact of baseline variables including metabolic traits and co-morbidities on the incidence of future major adverse cardiovascular events are shown. This data article is associated to the research article titled ‘The Novel Adipokine CTRP1 is Significantly Associated with the Incidence of Major Adverse Cardiovascular Events’ Muendlein et al., 2019.

Elevated CTRP1 Plasma Concentration Is Associated with Sepsis and Pre-Existing Type 2 Diabetes Mellitus in Critically Ill Patients

The adipokine family of C1q/TNF-like proteins (CTRP) plays a critical role in regulating systemic energy homeostasis and insulin sensitivity. It is involved in pathophysiological processes including inflammation and insulin-resistant obesity. Sepsis is associated with metabolic alterations and dysregulated adipokines, but the role of CTRP1 in critical illness and sepsis is unclear. We investigated CTRP1 plasma concentrations in 145 septic and 73 non-septic critically ill patients at admission to the medical intensive care unit (ICU) in comparison to 66 healthy controls. We also assessed associations of CTRP1 with clinical characteristics, adipokine levels, metabolic and inflammatory parameters. CTRP1 plasma concentration was significantly elevated in critically ill patients compared to healthy subjects. CTRP1 levels were significantly higher in ICU patients with sepsis. CTRP1 correlated strongly with markers of inflammatory response, renal function, liver damage and cholestasis. Furthermore, CTRP1 levels were higher in ICU patients with type 2 diabetes mellitus, and correlated with HbA1c and body mass index. This study demonstrates significantly elevated levels of CTRP1 in critically ill patients, particularly with sepsis, and links circulating CTRP1 to inflammatory and metabolic disturbances.

C1q and TNF related protein 1 regulates expression of inflammatory genes in vascular smooth muscle cells

BACKGROUND

C1q and TNF related protein 1 (C1QTNF1) is known to be associated with coronary artery diseases. However, the molecular function of C1QTNF1 on the vascular smooth muscles remains to be investigated.

OBJECTIVE

This study was therefore undertaken to investigate the effect of C1QTNF1 on gene expression of human smooth muscle cells and to reveal potential molecular mechanisms mediated by C1QTNF1.

METHODS

Vascular smooth muscle cells were incubated with recombinant C1QTNF1 for 16 h, followed by determining any change in mRNA expressions by Affymetrix genechip. Gene ontology (GO), KEGG pathway, and protein-protein interaction (PPI) network were analyzed in differentially expressed genes. In addition, validation of microarray data was performed using quantitative real-time PCR.

RESULTS

The mRNA expressions of annotated 74 genes were significantly altered after incubation with recombinant C1QTNF1; 41 genes were up-regulated and 33 down-regulated. The differentially expressed genes were enriched in biological processes and KEGG pathways associated with inflammatory responses. In the PPI network analysis, IL-6, CCL2, and ICAM1 were identified as potential key genes with relatively high degree. The cluster analysis in the PPI network identified a significant module composed of upregulated genes, such as IL-6, CCL2, NFKBIA, SOD2, and ICAM1. The quantitative real-time PCR results of potential key genes were consistent with microarray data.

CONCLUSION

The results in the present study provide insights on the effects of C1QTNF1 on gene expression of smooth muscle cells. We believe our findings will help to elucidate the molecular mechanisms regarding the functions of C1QTNF1 on smooth muscle cells in inflammatory diseases.

Obesity and chronic kidney disease progression-the role of a new adipocytokine: C1q/tumour necrosis factor-related protein-1

Background

Obesity is a risk factor for incident chronic kidney disease (CKD) in the general population. C1q/tumour necrosis factor-related protein 1 (CTRP1) is a new adipokine with multiple vascular and metabolic effects and may modulate the association between obesity and vascular diseases. The aim of the study is to explore potential links between obesity, CTRP1 levels and CKD progression.

Methods

Patients with Stages 3 and 4 CKD without previous cardiovascular events were enrolled and divided into two groups according to body mass index (BMI). Demographic, clinical and analytical data and CTRP1 levels were collected at baseline. During follow-up, renal events [defined as dialysis initiation, serum creatinine doubling or a 50% decrease in estimated glomerular filtration rate (Modification of Diet in Renal Disease)] were registered.

Results

A total of 71 patients with CKD were divided into two groups: 25 obese (BMI >30 kg/m²) and 46 non-obese. CTRP1 in plasma at baseline was higher in obese patients [median (interquartile range) 360 (148) versus 288 (188) ng/mL, P = 0.041]. No significant association was found between CTRP1 levels and CKD stage, presence of diabetes, aldosterone and renin levels, or blood pressure. Obese patients had higher systolic blood pressure (P = 0.018) and higher high-sensitivity C-reactive protein (P = 0.019) and uric acid (P = 0.003) levels, without significant differences in the percentage of diabetic patients or albuminuria. During a mean follow-up of 65 months, 14 patients had a renal event. Patients with CTRP1 in the lowest tertile had more renal events, both in the overall sample (log rank: 5.810, P = 0.016) and among obese patients (log rank: 5.405, P = 0.020). Higher CTRP1 levels were associated with slower renal progression (hazard ratio 0.992, 95% confidence interval 0.986–0.998; P = 0.001) in a model adjusted for obesity, aspirin, albuminuria and renal function.

Conclusions

CTRP1 levels are higher in obese than in non-obese patients with CKD. High CTRP1 levels may have a renal protective role since they were associated with slower kidney disease progression. Interventional studies are needed to explore this hypothesis.

C1qTNF-related protein 1 improve insulin resistance by reducing phosphorylation of serine 1101 in insulin receptor substrate 1

C1qTNF-related protein 1 (CTRP1) is independently associated with type 2 diabetes. However, the relationship between CTRP1 and insulin resistance is still not established. This study aimed to explore the role of CTRP1 under the situation of insulin resistance in adipose tissue. Plasma CTRP1 level was investigated in type 2 diabetic subjects (n = 35) and non-diabetic subjects (n = 35). The relationship between CTRP1 and phosphorylation of multi insulin receptor substrate 1 (IRS-1) serine (Ser) sites was further explored. Our data showed that Plasma CTRP1 was higher and negative correlation with insulin resistance in diabetic subjects (r = -0.283, p = 0.018). Glucose utilisation test revealed that the glucose utilisation rate of mature adipocytes was improved by CTRP1 in the presence of insulin. CTRP1 was not only related to IRS-1 protein, but also negatively correlated with IRS-1 Ser1101 phosphorylation (r = -0.398, p = 0.031). Furthermore, Phosphorylation levels of IRS-1 Ser1101 were significantly lower after incubation with 40 ng/mL CTRP1 in mature adipocytes than those with no intervention (p < 0.05). There was no significant correlation between CTRP1 and other IRS-1 serine sites (Ser302, Ser307, Ser612, Ser636/639, and Ser789). Collectively, our results suggested that CTRP1 might improve insulin resistance by reducing the phosphorylation of IRS-1 Ser1101, induced in the situation of insulin resistance as a feedback adipokine.

C1q/TNF-related protein 1 prevents neointimal formation after arterial injury

BACKGROUND AND AIMS

Obesity contributes to the progression of vascular disorders. C1q/TNF-related protein (CTRP) 1 is a circulating adipokine, which is upregulated in obese complications including coronary artery disease. Here, we investigated the role of CTRP1 in regulation of vascular remodeling after mechanical injury and evaluated its potential mechanism.

METHODS

Mice were subjected to wire-induced injury of left femoral arteries. An adenoviral vector encoding CTRP1 (Ad-CTRP1) or β-galactosidase as a control was injected into the jugular vein of mice 3 days prior to surgery.

RESULTS

Systemic administration of Ad-CTRP1 to wild-type mice led to reduction of the neointimal thickening after wire-induced arterial injury and the number of bromodeoxyuridine-positive cells in injured vessels as compared with treatment with control vectors. Treatment of vascular smooth muscle cells (VSMCs) with CTRP1 protein attenuated proliferative activity and ERK phosphorylation in response to PDGF-BB. CTRP1 treatment increased cyclic AMP (cAMP) levels in VSMCs, and inhibition of adenylyl cyclase reversed the inhibitory effect of CTRP1 on VSMC growth and ERK phosphorylation. Antagonization of sphingosine-1-phosphaterote (S1P) receptor 2 blocked the effects of CTRP1 on cAMP production and VSMC growth. Furthermore, CTRP1-knockout mice had enhanced neointimal thickening following injury and increased numbers of proliferating cells in neointima compared to control WT mice.

CONCLUSIONS

These findings indicate that CTRP1 functions to prevent the development of pathological vascular remodeling by reducing VSMC growth through the cAMP-dependent pathway.

CTRP1 in Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease occurs in significant percentage of general population. NAFLD is closely associated with entire spectrum of metabolic-related disorders including diabetes, obesity, and cardiovascular diseases. Considering several similar pathways underpinning metabolic disorders, presence of common molecular mediators contributing to pathomechanism of these disorders is expected. Mounting evidence has demonstrated important role of adipokines in the context of NAFLD. Adipokines produced by different tissues, mainly adipose, modulate numerous pathways including glucose and fatty acid metabolism and inflammation. CTRPs (C1q/TNF-related proteins) are a recently identified family of adipokines in which adiponectin is the most well-known ones. CTRP1 is a member of this family which has captured attention in recent years. CTRP1 enhances glucose and fatty acid oxidation, improves insulin sensitivity, attenuates plaque formation, and increases aldosterone production. Hence, various roles in metabolic pathways can link CTRP1 to NAFLD pathogenesis.

C1q/TNF-related protein-1: an adipokine marking and promoting atherosclerosis

AIMS

We investigated the association of the adipokine C1q/TNF-related protein (CTRP) 1 with coronary artery disease (CAD), and the biological vascular effects of CTRP1.

METHODS AND RESULTS

We analysed CTRP1 levels in sera of CAD patients (n = 451) and non-CAD controls (n = 686), and in coronary endarterectomy specimens (n = 32), non-atherosclerotic internal mammary arteries (n = 26), aortic atherosclerotic plaques (n = 15), and non-atherosclerotic aortic samples (n = 10). C1q/TNF-related protein-levels were higher in sera, endarterectomy specimens, aortic atherosclerotic plaques, and peripheral blood mononuclear cells (PBMCs) from CAD patients compared with controls, and were related to CAD severity. The production of CTRP1 was profusely induced by inflammatory cytokines and itself caused a concentration-dependent expression of adhesion molecules and inflammatory markers in human endothelial cells, human peripheral blood monocytes, and THP-1 cells. C1q/TNF-related protein-1 induced p38-dependent monocyte-endothelium adhesion in vitro and the recruitment of leucocytes to mesenteric venules in C57BL/6 mice. Immunohistochemistry of atherosclerotic femoral arteries exhibited CD68 and VE-cadherin loci-associated increased CTRP1 expression in plaques. Compared with saline, intraperitoneal injection of recombinant CTRP1 protein (200 μg/kg) every other day promoted atherogenesis in apoE(-/-) mice at 24 weeks. However, pro-atherogenic effects were significantly attenuated in CTRP1(-/-)/apoE(-/-) double-knockout mice compared with apoE(-/-) mice, with a consistent decrease in vascular adhesion molecule, phospho-p38 and TNF-α expression and macrophage infiltration in plaque in CTRP1(-/-) and double-knockout mice. Tumour necrosis factor-α-induced expression of adhesion molecules and cytokines were lower in primary endothelial cells and macrophages from CTRP(-/-) mice than in those from C57BL/6 mice.

CONCLUSION

C1q/TNF-related protein-1 is a marker of atherosclerosis in humans and promotes atherogenesis in mice.

C1q/TNF-related protein-1 functions to protect against acute ischemic injury in the heart

Obesity is associated with an increased risk of cardiovascular disease. C1q/TNF-related protein (CTRP)-1 is a poorly characterized adipokine that is up-regulated in association with ischemic heart disease. We investigated the role of CTRP1 in myocardial ischemia injury. CTRP1-knockout mice showed increased myocardial infarct size, cardiomyocyte apoptosis, and proinflammatory gene expression after I/R compared with wild-type (WT) mice. In contrast, systemic delivery of CTRP1 attenuated myocardial damage after I/R in WT mice. Treatment of cardiomyocytes with CTRP1 led to reduction of hypoxia-reoxygenation-induced apoptosis and lipopolysaccharide-stimulated expression of proinflammatory cytokines, which was reversed by inhibition of sphingosine-1-phosphate (S1P) signaling. Treatment of cardiomyocytes with CTRP1 also resulted in the increased production of cAMP, which was blocked by suppression of S1P signaling. The antiapoptotic and anti-inflammatory actions of CTRP1 were cancelled by inhibition of adenylyl cyclase or knockdown of adiponectin receptor 1. Furthermore, blockade of S1P signaling reversed CTRP1-mediated inhibition of myocardial infarct size, apoptosis, and inflammation after I/R in vivo. These data indicate that CTRP1 protects against myocardial ischemic injury by reducing apoptosis and inflammatory response through activation of the S1P/cAMP signaling pathways in cardiomyocytes, suggesting that CTRP1 plays a crucial role in the pathogenesis of ischemic heart disease.