CTRP1 protein enhances fatty acid oxidation via AMP-activated protein kinase (AMPK) activation and acetyl-CoA carboxylase (ACC) inhibition

Association of serum CTRP4 levels with vascular endothelial function in patients with type 2 diabetes mellitus: CTRP4 ameliorating inflammation, proliferation and migration in human umbilical vein endothelial cells

OBJECTIVE

We investigated the correlation between serum C1q/TNF-related protein 4 (CTRP4) level and flow-mediated dilation (FMD) in patients with type 2 diabetes mellitus (T2DM), and evaluated the biological effects of CTRP4 on human umbilical vein endothelial cells (HUVECs).

METHODS

A group of 165 patients diagnosed with T2DM were included in this study. Endothelial function was measured with the examination of brachial artery FMD. ELISA kit was used to measure the levels of CTRP4 in serum. HUVECs were stimulated with recombinant CTRP4 protein to assess its biological functions.

RESULTS

The levels of CTRP4 showed a significant variation among three groups based on FMD tertiles (p = 0.001). What's more, FMD had a significant difference among three CTRP4 tertile groups (p < 0.05) and was negatively related to serum CTRP4 levels (r = -0.270, p < 0.001). In T2DM patients, logistic regression analysis demonstrated that CTRP4 was the primary influence factor of low FMD (p < 0.01). In receiver operating characteristic curve analysis, the area under the curve of CTRP4 for predicting low FMD was 0.66 (95%CI 0.58-0.75). When stimulated HUVECs with recombinant CTRP4 protein, we found that CTRP4 could concentration-dependently ameliorate proliferation and migration of HUVECs in wounding healing and transwell assay. This protein could also decrease the expression of IL-6 and TNF-α and promote the release of NO in HUVEC supernatants, with suppression of NF-κB and STAT3 phosphorylation.

CONCLUSIONS

Serum CTRP4 concentrations were negatively associated with FMD. CTRP4 alleviated proliferation, migration and inflammation in HUVECs through the suppression of NF-κB and STAT3 signaling pathways.

Distinct spectral signatures unfold ECM stiffness-triggered biochemical changes in breast cancer cells

Cancer progression often accompanies the stiffening of extracellular matrix (ECM) in and around the tumor, owing to extra deposition and cross-linking of collagen. Stiff ECM has been linked with poor prognosis and is known to fuel invasion and metastasis, notably in breast cancer. However, the underlying biochemical or metabolic changes and the cognate molecular signatures remain elusive. Here, we explored Raman spectroscopy to unveil the spectral fingerprints of breast cancer cells in response to extracellular mechanical cues. Using stiffness-tuneable hydrogels, we showed that cells grown on stiff ECM displayed morphological changes with high proliferation. We further demonstrated that Raman Spectroscopy, a label-free and non-invasive technique, could provide comprehensive information about the biochemical environment of breast cancer cells in response to varying ECM stiffness. Raman spectroscopic analysis classified the cells into distinct clusters based on principal component-based linear discriminant analysis (PC-LDA). Multivariate curve resolution-alternating least squares (MCR-ALS) analysis indicated that cells cultured on stiff ECM exhibited elevated nucleic acid content and lesser lipids. Interestingly, increased intensity of Raman bands corresponding to cytochrome-c was also observed in stiff ECM conditions, suggesting mitochondrial modulation. The key findings harboured by spectral profiles were also corroborated by transmission electron microscopy, confirming altered metabolic status as reflected by increased mitochondria number and decreased lipid droplets in response to ECM stiffening. Collectively, these findings not only give the spectral signatures for mechanoresponse but also provide the landscape of biochemical changes in response to ECM stiffening.

Effects of Cinnamon (Cinnamomum zeylanicum) Extract on Adipocyte Differentiation in 3T3-L1 Cells and Lipid Accumulation in Mice Fed a High-Fat Diet

Flavonoids and phenolic acid are two of the rich polyphenols found in cinnamon (Cinnamomum zeylanicum). The effects of cinnamon extract on the inhibition of adipocyte differentiation in 3T3-L1 fibroblast cells and prohibitory lipid accumulation in male mice fed a high-fat diet were examined. Upon treating 3T3-L1 cells with cinnamon for 3 days, the cinnamon inhibited lipid accumulation and increased gene expression levels, such as those of adiponectin and leptin. In in vivo experiments, mice were randomized into four groups after a one-week acclimation period, as follows: normal diet, normal diet + 1% cinnamon extract, high-fat diet, and high-fat diet + 1% cinnamon extract. After 14 weeks of supplementation, we found that cinnamon extract increased the expression of lipolysis-related proteins, such as AMPK, p-ACC, and CPT-1, and reduced the expression of lipid-synthesis-related proteins, such as SREBP-1c and FAS, in liver tissue. Our results show that cinnamon extract may exhibit anti-obesity effects via the inhibition of lipid synthesis and adipogenesis and the induction of lipolysis in both 3T3-L1 fibroblast cells and mice fed a high-fat diet. Accordingly, cinnamon extract may have potential anti-obesity effects.

Lipid and glucose metabolism in senescence

Senescence is an inevitable biological process. Disturbances in glucose and lipid metabolism are essential features of cellular senescence. Given the important roles of these types of metabolism, we review the evidence for how key metabolic enzymes influence senescence and how senescence-related secretory phenotypes, autophagy, apoptosis, insulin signaling pathways, and environmental factors modulate glucose and lipid homeostasis. We also discuss the metabolic alterations in abnormal senescence diseases and anti-cancer therapies that target senescence through metabolic interventions. Our work offers insights for developing pharmacological strategies to combat senescence and cancer.

Anti-Obesity Effects of SPY Fermented with Lactobacillus rhamnosus BST-L.601 via Suppression of Adipogenesis and Lipogenesis in High-Fat Diet-Induced Obese Mice

In this research, the potential anti-obesity efficacy of Lactobacillus rhamnosus BST-L.601 and its fermented product (named SPY) with mashed sweet potato paste were investigated using 3T3-L1 preadipocytes and high-fat diet (HD)-induced obese mice. SPY (0-0.5 mg/mL) dose-dependently and significantly reduced lipid accumulation and TG content and the expression of adipogenic markers (C/EBPα, PPAR-γ, and aP2) and fatty acid synthetic pathway proteins (ACC and FAS) in 3T3-L1 adipocytes, demonstrating that SPY suppresses adipocyte differentiation and lipogenesis. Oral administration of SPY (4 × 10⁷ CFU/kg body weight) to HD-induced obese mice for 12 weeks significantly reduced the body and liver weight, the size of adipocytes, and the weight of epididymal, visceral, and subcutaneous fat tissues. SPY was more effective in decreasing body weight gain in HD mice than in treatment with BST-L.601 alone. Administration of SPY or BST-L.601 also reduced the serum level of total cholesterol and LDL cholesterol and leptin secretion at a similar level. These results revealed that both SPY and BST-L.601 effectively suppress HD-induced adipogenesis and lipogenesis, suggesting that these materials would be useful in the functional foods industry to ameliorate and/or prevent obesity.

Icariin, the main prenylflavonoid of Epimedii Folium, ameliorated chronic kidney disease by modulating energy metabolism via AMPK activation

ETHNOPHARMACOLOGICAL RELEVANCE

Epimedii Folium is a famous traditional Chinese medicine (TCM) widely used in classic formulas, Chinese patent drugs and health care products for treating kidney diseases. Therefore, we speculated that icariin, its main component, might also have a good therapeutic effect on chronic kidney disease (CKD).

AIM OF STUDY

To investigate the efficacy and potential mechanism of icariin on CKD.

MATERIALS AND METHODS

A CKD model was established by intragastric administration of adenine (200 mg/kg/d) to adult male SD rats for 28 consecutive days. TGF-β1-induced fibrotic HK-2 cells were applied to establish the renal fibrosis model in vitro. Biochemical determination, pathological staining, flow cytometry and ELISA were performed to preliminarily evaluate the renoprotection of icariin. The intervention effect of icariin on renal fibrosis progression was assessed by cell stiffness determination and multiple immunological methods. The potential mechanism of icariin on CKD was revealed by means of ¹H NMR metabolomics, qRT-PCR and Western blotting analysis.

RESULTS

Icariin at the dosage of 100 mg/kg/d and 200 mg/kg/d markedly ameliorated rat renal function in a dose-dependent manner. Based on renal pathological features, the mechanism of icariin intervention in CKD was initially revealed by metabolomics, which was closely related to energy metabolism pathways. Furthermore, the detection results of AMPK and related factors in its mediated signaling pathways indicated that icariin exerted a therapeutic effect on CKD by attenuating inflammation and oxidative stress responses and retarding renal fibrosis progression through regulating AMPK/SIRT1/NF-κB and AMPK/ACC signaling pathways.

CONCLUSION

It was the first time to demonstrate that icariin could treat adenine-induced CKD by modulating energy metabolism via AMPK activation in a dose-dependent manner.

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

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

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.

AMPK activation by AICAR reduces diet induced fatty liver in C57BL/6 mice

Dysregulation of 5'-adenosine monophosphate-activated protein kinase (AMPK) occurs in metabolic disorders including non-alcoholic fatty liver disease (NAFLD) which makes it a molecular target for treatment. An AMPK activator, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) alleviates NAFLD in experimental rats, however the specific mechanism remains to be explored. We aimed to study the effect of AICAR on lipid levels, oxidant-antioxidant balance, AMPK and mTOR activation and FOXO3 gene expression in liver of mice model. Fatty liver was induced in two groups of C57BL/6 mice (groups 2 and 3) by providing a high fat high fructose diet (HFFD) for 10 weeks while groups 1 and 4 animals were fed normal pellet. For the last two weeks, groups 3 and 4 were administered AICAR (150 mg/kg bw/day, i.p.) while groups 1 and 2 were administered saline. AICAR decreased fatty liver, decreased glucose and insulin in circulation, prevented the accumulation of triglycerides and collagen and ameliorated oxidative stress in HFFD fed mice. At the molecular level, AICAR upregulated FOXO3 and p-AMPK expression and reduced p-mTOR expression. AMPK activation may involve FOXO3 in protection against NAFLD. The role of AMPK, mTOR and FOXO3 crosstalk in NAFLD needs to be characterised in future.

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.

miR-214-5p/C1QTNF1 axis enhances PCV2 replication through promoting autophagy by targeting AKT/mTOR signaling pathway

Porcine circovirus type 2 (PCV2) is the causative agent of PCV2-associated disease, which causes a relevant economic impact on the global swine industry. Accumulating data have indicated host microRNAs play essential roles in numerous virus replication of pigs, while their roles in PCV2 replication remain unclear. Herein, we demonstrated that PCV2 infection downregulated the expression of miR-214-5p in PK15 cells, and miR-214-5p promoted PCV2 replication. C1q/tumor necrosis factor-related protein 1 (C1QTNF1) was then identified as a target gene of miR-214-5p, and C1QTNF1 suppressed PCV2 replication. Interestingly, miR-214-5p/C1QTNF1 axis negatively regulated AKT/mTOR signaling, and then enhanced PCV2 replication through promoting autophagy in PK15 cells. Collectively, our findings provide insight into the mechanism of PCV2 replication and highlight miR-214-5p and C1QTNF1 as potential novel targets for the treatment of PCV2 infection.

Responses of complement C1q/tumor necrosis factor-related proteins to acute aerobic exercise

Aerobic exercise is an effective therapeutic strategy to manage metabolic disorders. However, the mechanisms of aerobic exercise-induced improvements in metabolic diseases are not completely understood. Complement C1q/tumor necrosis factor-related protein (CTRP) 1, CTRP3, CTRP5, and CTRP9 have important roles in improving metabolic disorders via the adenosine monophosphate-activated protein kinase signaling pathway. In this study, we investigated the effects of acute aerobic exercise on circulating CTRP1, CTRP3, CTRP5, and CTRP9 levels in human participants. Eight healthy males with an age of 20.4 ± 0.2 years, height 173.1 ± 1.7 cm, body mass 68.0 ± 1.8 kg, body mass index 22.7 ± 0.7 kg/m², and maximal oxygen uptake (VO₂max) 51.3 ± 2.5 mL/kg/min performed acute aerobic cycling exercise at 75 % of their VO₂max for 30 min (data are mean ± standard error). Blood samples were obtained before; immediately after; and 30, 60, and 120 min after exercising. Serum concentrations of CTRP1, CTRP3, CTRP5, CTRP9, tumor necrosis factor-α (TNF-α), and insulin were measured. The CTRP1 concentration significantly increased immediately after exercising and remained elevated for up to 120 min (p < 0.01). The CTRP3 concentration significantly increased at 60 min after exercise (p < 0.05), and the increasing trend continued until at least 120 min after exercise (p < 0.01). The CTRP5, CTRP9, TNF-α, and insulin concentrations significantly increased immediately after exercise (p < 0.05, p < 0.01, p < 0.05, and p < 0.05, respectively) and decreased thereafter. A significant correlation was observed between the peak post-exercise concentrations of CTRP1 and TNF-α (p < 0.05); however, no correlation was observed between the peak post-exercise concentrations of CTRP3 and insulin. The results of this study indicate that acute aerobic exercise may enhance the secretion of CTRP1, CTRP3, CTRP5, and CTRP9 in healthy adults.

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.

AMPK: An odyssey of a metabolic regulator, a tumor suppressor, and now a contextual oncogene

Metabolic reprogramming is a unique but complex biochemical adaptation that allows solid tumors to tolerate various stresses that challenge cancer cells for survival. Under conditions of metabolic stress, mammalian cells employ adenosine monophosphate (AMP)-activated protein kinase (AMPK) to regulate energy homeostasis by controlling cellular metabolism. AMPK has been described as a cellular energy sensor that communicates with various metabolic pathways and networks to maintain energy balance. Earlier studies characterized AMPK as a tumor suppressor in the context of cancer. Later, a paradigm shift occurred in support of the oncogenic nature of AMPK, considering it a contextual oncogene. In support of this, various cellular and mouse models of tumorigenesis and clinicopathological studies demonstrated increased AMPK activity in various cancers. This review will describe AMPK's pro-tumorigenic activity in various malignancies and explain the rationale and context for using AMPK inhibitors in combination with anti-metabolite drugs to treat AMPK-driven cancers.

Acylation, a Conductor of Ghrelin Function in Brain Health and Disease

Acyl-ghrelin (AG) is an orexigenic hormone that has a unique octanoyl modification on its third serine residue. It is often referred to as the “hunger hormone” due to its involvement in stimulating food intake and regulating energy homeostasis. The discovery of the enzyme ghrelin-O-acyltransferase (GOAT), which catalyses ghrelin acylation, provided further insights into the relevance of this lipidation process for the activation of the growth hormone secretagogue receptor (GHS-R) by acyl-ghrelin. Although acyl-ghrelin is predominantly linked with octanoic acid, a range of saturated fatty acids can also bind to ghrelin possibly leading to specific functions. Sources of ghrelin acylation include beta-oxidation of longer chain fatty acids, with contributions from fatty acid synthesis, the diet, and the microbiome. In addition, both acyl-ghrelin and unacyl-ghrelin (UAG) have feedback effects on lipid metabolism which in turn modulate their levels. Recently we showed that whilst acyl-ghrelin promotes adult hippocampal neurogenesis and enhances memory function, UAG inhibits these processes. As a result, we postulated that the circulating acyl-ghrelin:unacyl-ghrelin (AG:UAG) ratio might be an important regulator of neurogenesis and cognition. In this review, we discuss emerging evidence behind the relevance of ghrelin acylation in the context of brain physiology and pathology, as well as the current challenges of identifying the provenance of the acyl moiety.

CTRP4 is Associated with Coronary Artery Disease in Patients with type 2 diabetes

Aims/Introduction

To evaluate the correlation of circulating C1q tumor necrosis factor‐related protein 4 (CTRP4) with coronary artery disease (CAD) in type 2 diabetes mellitus patients.

Methods

A total of 240 individuals with type 2 diabetes mellitus were enrolled in our center between January 2020 and December 2020. They were assigned into two groups, including the CAD and non‐CAD groups, based on coronary angiography or computed tomography angiography findings. Serum CTRP4 levels were detected by an enzyme‐linked immunosorbent assay kit. The association of CTRP4 with CAD was determined by logistic regression analysis. The predictive value of CTRP4 for CAD was calculated by receiver operating characteristic curve analysis.

Results

Median serum CTRP4 amounts were markedly elevated in the CAD group in comparison with the non‐CAD group (10.37 vs 3.75 ng/mL, P < 0.01). Binary logistic regression showed that CTRP4 was associated with CAD and even the amount of coronary artery lesions (P < 0.05). In receiver operating characteristic curve analysis, the area under the receiver operating characteristic curve was greater for CTRP4 compared with HbA1c or CRP (0.87 vs 0.74, 0.87 vs 0.80, P < 0.01). The area under the curve for CTRP4 and glycated hemoglobin in combination was larger than that obtained for CTRP4 combined with CRP (0.91 vs 0.87, P < 0.01). According to the maximum Youden index criteria, the optimal cut‐off of CTRP4 was 5.42 ng/mL, which yielded a sensitivity of 84.4% and a specificity of 76.7% in predicting CAD in type 2 diabetes mellitus patients.

Conclusions

Serum CTRP4 levels are positively correlated with CAD occurrence and severity. Combining CTRP4 and glycated hemoglobin has a better predictive value for CAD in type 2 diabetes mellitus patients.

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.

Mechanisms by Which Skeletal Muscle Myokines Ameliorate Insulin Resistance

The skeletal muscle is the largest organ in the body and secretes circulating factors, including myokines, which are involved in various cellular signaling processes. Skeletal muscle is vital for metabolism and physiology and plays a crucial role in insulin-mediated glucose disposal. Myokines have autocrine, paracrine, and endocrine functions, serving as critical regulators of myogenic differentiation, fiber-type switching, and maintaining muscle mass. Myokines have profound effects on energy metabolism and inflammation, contributing to the pathophysiology of type 2 diabetes (T2D) and other metabolic diseases. Myokines have been shown to increase insulin sensitivity, thereby improving glucose disposal and regulating glucose and lipid metabolism. Many myokines have now been identified, and research on myokine signaling mechanisms and functions is rapidly emerging. This review summarizes the current state of the field regarding the role of myokines in tissue cross-talk, including their molecular mechanisms, and their potential as therapeutic targets for T2D.

Fecal microbiota transplantation ameliorates atherosclerosis in mice with C1q/TNF-related protein 9 genetic deficiency

Despite the strong influence of the gut microbiota on atherosclerosis, a causal relationship between atherosclerosis pathophysiology and gut microbiota is still unverified. This study was performed to determine the impact of the gut microbiota on the pathogenesis of atherosclerosis caused by genetic deficiency. To elucidate the influence of the gut microbiota on atherosclerosis pathogenesis, an atherosclerosis-prone mouse model (C1q/TNF-related protein 9-knockout (CTRP9-KO) mice) was generated. The gut microbial compositions of CTRP9-KO and WT control mice were compared. Fecal microbiota transplantation (FMT) was performed to confirm the association between gut microbial composition and the progression of atherosclerosis. FMT largely affected the gut microbiota in both CTRP9-KO and WT mice, and all transplanted mice acquired the gut microbiotas of the donor mice. Atherosclerotic lesions in the carotid arteries were decreased in transplanted CTRP9-KO mice compared to CTRP9-KO mice prior to transplantation. Conversely, WT mice transplanted with the gut microbiotas of CTRP9-KO mice showed the opposite effect as that of CTRP9-KO mice transplanted with the gut microbiotas of WT mice. Here, we show that CTRP9 gene deficiency is related to the distribution of the gut microbiota in subjects with atherosclerosis. Transplantation of WT microbiotas into CTRP9-KO mice protected against the progression of atherosclerosis. Conversely, the transplantation of CTRP9-KO microbiotas into WT mice promoted the progression of atherosclerosis. Treating atherosclerosis by restoring gut microbial homeostasis may be an effective therapeutic strategy.

Total flavonoids in Epimedium koreanum Nakai alleviated chronic renal failure via promoting AMPK activation

Chronic renal failure (CRF) is a result of the progression of chronic kidney diseases (CKD), a global health problem with a high cost of treatment and no ideal therapy. The aim of this study is to evaluate the pharmacological efficacy of the total flavonoids in Epimedium koreanum Nakai (TFE), a dietary supplement, against CRF and to determine the mechanism of actions. An adenine-induced CRF rat model and a TGF-β1 induced human kidney proximal tubule epithelial (HK-2) cell based in vitro renal fibrosis model were established and used to evaluate TFE's efficacy. Renal hemodynamics, biochemical indexes, inflammatory cytokines, histopathology and the reactive oxygen species (ROS) levels were determined to evaluate the efficacy of TFE on CRF. NMR-based metabolomics, immunohistochemical (IHC) staining, immunofluorescence (IF) staining, quantitative real time-PCR (qRT-PCR) and western blotting were conducted to determine the mechanism. The results showed that TFE had a significant effect on CRF at 150 mg kg^-1 d^-1 and could significantly alleviate renal fibrosis in the animal model. Twelve potential biomarkers, which mainly involve energy metabolism pathways, for CRF were identified using the metabolomics approach. The mechanism study suggested that TFE regulated AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) and AMPK/silent information regulator 1 (SIRT1)/nuclear factor kappa-B (NF-κB) signaling pathways. Furthermore, the effect of TFE was inhibited by compound C in the in vitro experiment, which also confirmed the above conclusion.

Novel Adipokines CTRP1, CTRP9, and FGF21 in Pediatric Type 1 and Type 2 Diabetes: A Cross-Sectional Analysis

INTRODUCTION

Pediatric obesity and diabetes has increased over the last several decades. While the role of common adipokines on metabolic parameters has been well studied in adults, the relationship of novel adipokines and hepatokines in pediatric type 1 (T1D) and type 2 diabetes (T2D) is not well understood. This study assessed novel adipokines C1q/TNF-related proteins (CTRP1 and CTRP9), and hepatokine fibroblast growth factor 21 (FGF21) in youth with T1D and T2D diabetes.

METHODS

Participants (n = 80) with T1D (n = 40) enrolled in the Pediatric Diabetes Consortium (PDC) T1D NeOn registry, and T2D (n = 40) from the PDC T2D registry. Cross-sectional analysis compared adipokines (CTRP1, CTRP9, FGF21) between T1D and T2D, and regression models assessed adipokine relationship with clinical characteristics.

RESULTS

The mean age of the participants was 14.9 ± 2 years, and 50% were female. T2D participants had a shorter diabetes duration (p = 0.0009), higher weight (p < 0.0001), and BMI (p < 0.0001) than T1D participants. CTRP9 levels were higher in T1D (13,903.6 vs. 3,608.5 pg/mL, p = 0.04) than T2D, and FGF21 levels were higher in T2D (113.1 vs. 70.6 pg/mL, p = 0.03) than T1D, with no differences in CTRP1. In regression analysis of T1D, CTRP9 was positively associated with C-peptide (p = 0.006), and FGF21 was positively associated with hemoglobin A1c (p = 0.04). In T2D, CTRP1 was positively associated with HbA1c (p < 0.001) and glucose (p = 0.004), even after controlling for age, sex, and BMI.

CONCLUSIONS

CTRP9 levels are higher in youth with T1D compared to T2D, and FGF21 levels are higher in youth with T2D than T1D. Novel adipokines are related to metabolic homeostasis in the inflammatory milieu of pediatric diabetes.

C1q/TNF-related protein-1: Potential biomarker for early diagnosis of autism spectrum disorder

INTRODUCTION

Autism spectrum disorders (ASDs) are neurodevelopmental diseases characterized by communication inabilities, social interaction impairment, repetitive behavior, as well as learning problems. Although the exact mechanism underlying this disease is still obscure, researchers believe that several factors play a significant role in its development and pathogenesis. Some authors have reported an association between adipokines family and autism. C1q/TNF-related protein-1 (CTRP1) is a member of the adipokines family, and we hypothesized that this adipokine might have an influential role in the pathogenesis of ASDs. Since there is no specific marker for screening the disease, we evaluated CTRP1 as a potential marker for achieving this purpose.

METHODS

Blood samples were collected from 82 (41 ASDs boys, 41 healthy boys as controls) children aged 5-7 years old. CTRP1 gene expression and CTRP1 serum level were measured by quantitative realtime-PCR and enzyme-linked immunosorbent assay methods, respectively.

RESULTS

It was found that CTRP1 is significantly elevated in autistic children in comparison to healthy controls, both at the gene expression level, as well as at the serum level; demonstrating a good diagnostic value with a good range of sensitivity and specificity for detecting ASDs.

CONCLUSION

CTRP1 expression is elevated in ASDs boys aged 5-7 years old, suggesting a role for this adipokine in ASDs pathophysiology. Also, receiver operating characteristic curve analyses revealed that this adipokine could be utilized as a diagnostic biomarker for differentiating ASDs patients from healthy individuals along with other recently proposed biomarkers.

CTRP4 ablation impairs associative learning and memory

C1q/TNF-related protein (CTRP) family comprises fifteen highly conserved secretory proteins with diverse central and peripheral functions. In zebrafish, mouse, and human, CTRP4 is most highly expressed in the brain. We previously showed that CTRP4 is a metabolically responsive regulator of food intake and energy balance, and mice lacking CTRP4 exhibit sexually dimorphic changes in ingestive behaviors and systemic metabolism. Recent single-cell RNA sequencing also revealed Ctrp4/C1qtnf4 expression in diverse neuronal cell types across distinct anatomical brain regions, hinting at additional roles in the central nervous system not previously characterized. To uncover additional central functions of CTRP4, we subjected Ctrp4 knockout (KO) mice to a battery of behavioral tests. Relative to wild-type (WT) littermates, loss of CTRP4 does not alter exploratory, anxiety-, or depressive-like behaviors, motor function and balance, sensorimotor gating, novel object recognition, and spatial memory. While pain-sensing mechanisms in response to thermal stress and mild shock are intact, both male and female Ctrp4 KO mice have increased sensitivity to pain induced by higher-level shock, suggesting altered nociceptive function. Importantly, CTRP4 deficiency impairs hippocampal-dependent associative learning and memory as assessed by trace fear conditioning paradigm. This deficit is sex-dependent, affects only female mice, and is associated with altered expression of learning and memory genes (Arc, c-fos, and Pde4d) in the hippocampus and cortex. Altogether, our behavioral and gene expression analyses have uncovered novel aspects of the CTRP4 function and provided a physiological context to further investigate its mechanism of action in the central and peripheral nervous system.

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.

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.

Altered adipokines in obese adolescents: a cross-sectional and longitudinal analysis across the spectrum of glycemia

Obesity and type 2 diabetes are rapidly increasing in the adolescent population. We sought to determine whether adipokines, specifically leptin, C1q/TNF-related proteins 1 (CTRP1) and CTRP9, and the hepatokine fibroblast growth factor 21 (FGF21), are associated with obesity and hyperglycemia in a cohort of lean and obese adolescents, across the spectrum of glycemia. In an observational, longitudinal study of lean and obese adolescents, we measured fasting laboratory tests, oral glucose tolerance tests, and adipokines including leptin, CTRP1, CTRP9, and FGF21. Participants completed baseline and 2-year follow-up study visits and were categorized as lean (LC, lean control; n = 30), obese normoglycemic (ONG; n = 61), and obese hyperglycemic (OHG; n = 31) adolescents at baseline and lean (n = 8), ONG (n = 18), and OHG (n = 4) at follow-up. Groups were compared using ANOVA and regression analysis, and linear mixed effects modeling was used to test for differences in adipokine levels across baseline and follow-up visits. Results showed that at baseline, leptin was higher in all obese groups (P < 0.001) compared with LC. FGF21 was higher in OHG participants compared with LC (P < 0.001) and ONG (P < 0.001) and positively associated with fasting glucose (P < 0.001), fasting insulin (P < 0.001), Homeostasis Model Assessment-Insulin Resistance Index (HOMA-IR; P < 0.001), and hemoglobin A1c (HbA1c; P = 0.01). CTRP1 was higher in OHG compared with ONG (P = 0.03). CTRP9 was not associated with obesity or hyperglycemia in this pediatric cohort. At 2 years, leptin decreased in ONG (P = 0.003) and FGF21 increased in OHG (P = 0.02), relative to lean controls. Altered adipokine levels are associated with the inflammatory milieu in obese youth with and without hyperglycemia. In adolescence, the novel adipokine CTRP1 was elevated with hyperglycemia, whereas CTRP9 was unchanged in this cohort.NEW & NOTEWORTHY Leptin is higher in obese adolescents and FGF21 is higher in obese hyperglycemic adolescents. The novel adipokine CTRP1 is higher in obese hyperglycemic adolescents, whereas CTRP9 was unchanged in this adolescent cohort.

Extracellular Matrix Stiffness: New Areas Affecting Cell Metabolism

In recent years, in-depth studies have shown that extracellular matrix stiffness plays an important role in cell growth, proliferation, migration, immunity, malignant transformation, and apoptosis. Most of these processes entail metabolic reprogramming of cells. However, the exact mechanism through which extracellular matrix stiffness leads to metabolic reprogramming remains unclear. Insights regarding the relationship between extracellular matrix stiffness and metabolism could help unravel novel therapeutic targets and guide development of clinical approaches against a myriad of diseases. This review provides an overview of different pathways of extracellular matrix stiffness involved in regulating glucose, lipid and amino acid metabolism.

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.

Anti-influenza A Virus Effects and Mechanisms of Emodin and Its Analogs via Regulating PPARα/γ-AMPK-SIRT1 Pathway and Fatty Acid Metabolism

The peroxisome proliferator-activated receptor (PPAR) α/γ-adenosine 5'-monophosphate- (AMP-) activated protein kinase- (AMPK-) sirtuin-1 (SIRT1) pathway and fatty acid metabolism are reported to be involved in influenza A virus (IAV) replication and IAV-pneumonia. Through a cell-based peroxisome proliferator responsive element- (PPRE-) driven luciferase bioassay, we have investigated 145 examples of traditional Chinese medicines (TCMs). Several TCMs, such as Polygonum cuspidatum, Rheum officinale Baillon, and Aloe vera var. Chinensis (Haw.) Berg., were found to possess high activity. We have further detected the anti-IAV activities of emodin (EMO) and its analogs, a group of common important compounds of these TCMs. The results showed that emodin and its several analogs possess excellent anti-IAV activities. The pharmacological tests showed that emodin significantly activated PPARα/γ and AMPK, decreased fatty acid biosynthesis, and increased intracellular ATP levels. Pharmaceutical inhibitors, siRNAs for PPARα/γ and AMPKα1, and exogenous palmitate impaired the inhibition of emodin. The in vivo test also showed that emodin significantly protected mice from IAV infection and pneumonia. Pharmacological inhibitors for PPARα/γ and AMPK signal and exogenous palmitate could partially counteract the effects of emodin in vivo. In conclusion, emodin and its analogs are a group of promising anti-IAV drug precursors, and the pharmacological mechanism of emodin is linked to its ability to regulate the PPARα/γ-AMPK pathway and fatty acid metabolism.

Aging and chronic high-fat feeding negatively affect kidney size, function, and gene expression in CTRP1-deficient mice

C1q/TNF-related protein 1 (CTRP1) is an endocrine factor with metabolic, cardiovascular, and renal functions. We previously showed that aged Ctrp1-knockout (KO) mice fed a control low-fat diet develop renal hypertrophy and dysfunction. Since aging and obesity adversely affect various organ systems, we hypothesized that aging, in combination with obesity induced by chronic high-fat feeding, would further exacerbate renal dysfunction in CTRP1-deficient animals. To test this, we fed wild-type and Ctrp1-KO mice a high-fat diet for 8 mo or longer. Contrary to our expectation, no differences were observed in blood pressure, heart function, or vascular stiffness between genotypes. Loss of CTRP1, however, resulted in an approximately twofold renal enlargement (relative to body weight), ∼60% increase in urinary total protein content, and elevated pH, and changes in renal gene expression affecting metabolism, signaling, transcription, cell adhesion, solute and metabolite transport, and inflammation. Assessment of glomerular integrity, the extent of podocyte foot process effacement, as well as renal response to water restriction and salt loading did not reveal significant differences between genotypes. Interestingly, blood platelet, white blood cell, neutrophil, lymphocyte, and eosinophil counts were significantly elevated, whereas mean corpuscular volume and hemoglobin were reduced in Ctrp1-KO mice. Cytokine profiling revealed increased circulating levels of CCL17 and TIMP-1 in KO mice. Compared with our previous study, current data suggest that chronic high-fat feeding affects renal phenotypes differently than similarly aged mice fed a control low-fat diet, highlighting a diet-dependent contribution of CTRP1 deficiency to age-related changes in renal structure and function.

Loss of CTRP4 alters adiposity and food intake behaviors in obese mice

Central and peripheral mechanisms are both required for proper control of energy homeostasis. Among circulating plasma proteins, C1q/TNF-related proteins (CTRPs) have recently emerged as important regulators of sugar and fat metabolism. CTRP4, expressed in brain and adipose tissue, is unique among the family members in having two tandem globular C1q domains. We previously showed that central administration of recombinant CTRP4 suppresses food intake, suggesting a central nervous system role in regulating ingestive physiology. Whether this effect is pharmacological or physiological remains unclear. We used a loss-of-function knockout (KO) mouse model to clarify the physiological role of CTRP4. Under basal conditions, CTRP4 deficiency increased serum cholesterol levels and impaired glucose tolerance in male but not female mice fed a control low-fat diet. When challenged with a high-fat diet, male and female KO mice responded differently to weight gain and had different food intake patterns. On an obesogenic diet, male KO mice had similar weight gain as wild-type littermates. When fed ad libitum, KO male mice had greater meal number, shorter intermeal interval, and reduced satiety ratio. Female KO mice, in contrast, had lower body weight and adiposity. In the refeeding period following food deprivation, female KO mice had significantly higher food intake due to longer meal duration and reduced satiety ratio. Collectively, our data provide genetic evidence for a sex-dependent physiological role of CTRP4 in modulating food intake patterns and systemic energy metabolism.

Adipokines: New Potential Therapeutic Target for Obesity and Metabolic, Rheumatic, and Cardiovascular Diseases

Besides its role as an energy storage organ, adipose tissue can be viewed as a dynamic and complex endocrine organ, which produces and secretes several adipokines, including hormones, cytokines, extracellular matrix (ECM) proteins, and growth and vasoactive factors. A wide body of evidence showed that adipokines play a critical role in various biological and physiological functions, among which feeding modulation, inflammatory and immune function, glucose and lipid metabolism, and blood pressure control. The aim of this review is to summarize the effects of several adipokines, including leptin, diponectin, resistin, chemerin, lipocalin-2 (LCN2), vaspin, omentin, follistatin-like 1 (FSTL1), secreted protein acidic and rich in cysteine (SPARC), secreted frizzled-related protein 5 (SFRP5), C1q/TNF-related proteins (CTRPs), family with sequence similarity to 19 member A5 (FAM19A5), wingless-type inducible signaling pathway protein-1 (WISP1), progranulin (PGRN), nesfatin-1 (nesfatin), visfatin/PBEF/NAMPT, apelin, retinol binding protein 4 (RPB4), and plasminogen activator inhibitor-1 (PAI-1) in the regulation of insulin resistance and vascular function, as well as many aspects of inflammation and immunity and their potential role in managing obesity-associated diseases, including metabolic, osteoarticular, and cardiovascular diseases.

CTRP-1 levels are related to insulin resistance in pregnancy and gestational diabetes mellitus

Recent studies have shown higher levels of CTRP-1 (C1QTNF-related protein) in patients with type 2 diabetes compared to controls. We aimed at investigating CTRP-1 in gestational diabetes mellitus (GDM). CTRP-1 levels were investigated in 167 women (93 with normal glucose tolerance (NGT), 74 GDM) of a high-risk population for GDM. GDM was further divided into GDM subtypes depending on a predominant insulin sensitivity issue (GDM-IR) or secretion deficit (GDM-IS). Glucose tolerance was assessed with indices [Matsuda index, Stumvoll first phase index, insulin-secretion-sensitivity-index 2 (ISSI-2), area-under-the-curve (AUC) insulin, AUC glucose] derived from an oral glucose tolerance test (oGTT) performed at < 21 and 24–28 weeks of gestation. In pregnancy, CTRP-1 levels of GDM (76.86 ± 37.81 ng/ml) and NGT (82.2 ± 35.34 ng/ml; p = 0.104) were similar. However, GDM-IR women (65.18 ± 42.18 ng/ml) had significantly lower CTRP-1 levels compared to GDM-IS (85.10 ± 28.14 ng/ml; p = 0.009) and NGT (p = 0.006). CTRP-1 levels correlated negatively with weight, AUC insulin, Stumvoll first phase index, bioavailable estradiol and positively with HbA1c, Matsuda Index and ISSI-2. A multiple regression analysis revealed bioavailable estradiol (β = − 0.280, p = 0.008) and HbA1c (β = 0.238; p = 0.018) as the main variables associated with CTRP-1 in GDM. Postpartum, waist and hip measurements were predictive of CRTP-1 levels instead. CTRP-1 levels were higher postpartum than during pregnancy (91.92 ± 47.27 vs.82.44 ± 38.99 ng/ml; p = 0.013). CTRP-1 is related to insulin resistance in pregnancy and might be a metabolic biomarker for insulin resistance in GDM. CTRP-1 levels were significantly lower during pregnancy than postpartum, probably due to rising insulin resistance during pregnancy.

CTRP12 inhibits triglyceride synthesis and export in hepatocytes by suppressing HNF-4α and DGAT2 expression

C1q/TNF-related protein 12 (CTRP12) is an antidiabetic adipokine whose circulating levels are reduced in obesity and diabetes. Although partial and complete loss-of-function mouse models suggest a role for CTRP12 in modulating lipid metabolism and adiposity, its effect on cellular lipid metabolism remains poorly defined. Here, we demonstrate a direct action of CTRP12 in regulating lipid synthesis and secretion. In hepatoma cells and primary mouse hepatocytes, CTRP12 treatment inhibits triglyceride synthesis by suppressing glycerophosphate acyltransferase (GPAT) and diacylglycerol acyltransferase (DGAT) expression. CTRP12 treatment also downregulates the expression of hepatocyte nuclear factor-4α (HNF-4α) and its target gene microsomal triglyceride transfer protein (MTTP), leading to reduced very-low-density lipoprotein (VLDL)-triglyceride export from hepatocytes. Consistent with the in vitro findings, overexpressing CTRP12 lowers fasting and postprandial serum triglyceride levels in mice. These results underscore the important function of CTRP12 in lipid metabolism in hepatocytes.

Dynamic chromatin accessibility landscape changes following interleukin-1 stimulation

Dynamic modifications of chromatin allow rapid access of the gene regulatory machinery to condensed genomic regions facilitating subsequent gene expression. Inflammatory cytokine stimulation of cells can cause rapid gene expression changes through direct signalling pathway-mediated transcription factor activation and regulatory element binding.

Here we used the Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq) to assess regions of the genome that are differentially accessible following treatment of cells with interleukin-1 (IL-1). We identified 126,483 open chromatin regions, with 241 regions significantly differentially accessible following stimulation, with 64 and 177 more or less accessible, respectively. These differentially accessible regions predominantly correspond to regions of the genome marked as enhancers. Motif searching identified an overrepresentation of a number of transcription factors, most notably RelA, in the regions becoming more accessible, with analysis of ChIP-seq data confirmed RelA binding to these regions. A significant correlation in differential chromatin accessibility and gene expression was also observed.

Functionality in regulating gene expression was confirmed using CRISPR/Cas9 genome-editing to delete regions that became more accessible following stimulation in the genes MMP13, IKBKE and C1QTNF1. These same regions were also accessible for activation using a dCas9-transcriptional activator and showed enhancer activity in a cellular model.

Together, these data describe and functionally validate a number of dynamically accessible chromatin regions involved in inflammatory signalling.

CTRP12 ablation differentially affects energy expenditure, body weight, and insulin sensitivity in male and female mice

Secreted hormones facilitate tissue cross talk to maintain energy balance. We previously described C1q/TNF-related protein 12 (CTRP12) as a novel metabolic hormone. Gain-of-function and partial-deficiency mouse models have highlighted important roles for this fat-derived adipokine in modulating systemic metabolism. Whether CTRP12 is essential and required for metabolic homeostasis is unknown. We show here that homozygous deletion of Ctrp12 gene results in sexually dimorphic phenotypes. Under basal conditions, complete loss of CTRP12 had little impact on male mice, whereas it decreased body weight (driven by reduced lean mass and liver weight) and improved insulin sensitivity in female mice. When challenged with a high-fat diet, Ctrp12 knockout (KO) male mice had decreased energy expenditure, increased weight gain and adiposity, elevated serum TNFα level, and reduced insulin sensitivity. In contrast, female KO mice had reduced weight gain and liver weight. The expression of lipid synthesis and catabolism genes, as well as profibrotic, endoplasmic reticulum stress, and oxidative stress genes were largely unaffected in the adipose tissue of Ctrp12 KO male mice. Despite greater adiposity and insulin resistance, Ctrp12 KO male mice fed an obesogenic diet had lower circulating triglyceride and free fatty acid levels. In contrast, lipid profiles of the leaner female KO mice were not different from those of WT controls. These data suggest that CTRP12 contributes to whole body energy metabolism in genotype-, diet-, and sex-dependent manners, underscoring complex gene-environment interactions influencing metabolic outcomes.

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.

C1q/TNF-related Protein 1, a Multifunctional Adipokine: An Overview of Current Data

The present review aimed to present the research highlights on C1q/TNF-related protein 1 (CTRP1), a member of the recently discovered family of highly conserved adiponectin paralog proteins, C1q tumor necrosis factor-related proteins. CTRP1 plays an important role in regulating body energy homeostasis and sensitivity to insulin. Studies on animal models have shown that it lowers the concentration of glucose. Elevated concentrations of CTRP1 reduce weight gain and diet-induced insulin resistance. CTRP1 limits the extent of ischemia-reperfusion injury in acute myocardial infarction. It inhibits platelet aggregation by blocking von Willebrand factor binding to collagen. In patients with chronic kidney disease, an increase in CTRP1 levels is associated with a lesser degree of disease progression. CTRP1 stimulates aldosterone synthesis in the adrenal cortex by affecting aldosterone synthase expression. In dehydration, an increase in CTRP1 concentration helps to maintain normotension. It participates in processes related to the proliferation and maturation of chondrocytes. It also promotes atherosclerosis, and a surge in its concentration is correlated with a higher cardiovascular risk in patients with coronary atherosclerosis. In vascular smooth muscle cells, it induces the expression of proinflammatory cytokines. An increase in CTRP1 levels is correlated with the progression of the neoplastic process in patients with glioblastoma.

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.

Late-onset renal hypertrophy and dysfunction in mice lacking CTRP1

Local and systemic factors that influence renal structure and function in aging are not well understood. The secretory protein C1q/TNF-related protein 1 (CTRP1) regulates systemic metabolism and cardiovascular function. We provide evidence here that CTRP1 also modulates renal physiology in an age- and sex-dependent manner. In mice lacking CTRP1, we observed significantly increased kidney weight and glomerular hypertrophy in aged male but not female or young mice. Although glomerular filtration rate, plasma renin and aldosterone levels, and renal response to water restriction did not differ between genotypes, CTRP1-deficient male mice had elevated blood pressure. Echocardiogram and pulse wave velocity measurements indicated normal heart function and vascular stiffness in CTRP1-deficient animals, and increased blood pressure was not due to greater salt retention. Paradoxically, CTRP1-deficient mice had elevated urinary sodium and potassium excretion, partially resulting from reduced expression of genes involved in renal sodium and potassium reabsorption. Despite renal hypertrophy, markers of inflammation, fibrosis, and oxidative stress were reduced in CTRP1-deficient mice. RNA sequencing revealed alterations and enrichments of genes in metabolic processes in CTRP1-deficient animals. These results highlight novel contributions of CTRP1 to aging-associated changes in renal physiology.

C1q/TNF-related Protein 4 Induces Signal Transducer and Activator of Transcription 3 Pathway and Modulates Food Intake

C1q/TNF-related protein 4 (CTRP4) has been reported to decrease food intake and regulate energy homeostasis. However, its underlying mechanism and signaling pathway remain unknown. Using an adenovirus-mediated hypothalamic CTRP4 overexpression model, we investigated the impact of CTRP4 on food intake and signal transducer and activator of transcription 3 (STAT3) signaling pathway in normal chow-fed mice. Expressions of neuropeptides including proopiomelanocortin (POMC) and neuropeptide Y (NPY) were studied in hypothalamus by Western blot and immunochemistry. STAT3 and suppressor of cytokine signaling 3 (SOCS3) were determined by Western blot. STAT3 signaling pathway was also investigated in Neuro 2A (N2a) cells after CTRP4 overexpression intervention. We found that food intake decreased significantly in mice under normal chow condition after CTRP4 overexpression. Both immunohistochemistry and Western blot demonstrated that POMC expression was significantly increased while NPY expression was significantly decreased. The changes of neuropeptides were accompanied by significant increased STAT3 phosphorylation and decreased SOCS3 levels. The same changes of neuropeptides and STAT3 signaling were also found in N2a cells after CTRP4 overexpression intervention. Collectively, our data reveals that CTRP4 induces the activation of STAT3 signaling and decreases food intake.

Anti-inflammatory Property of AMP-activated Protein Kinase

BACKGROUND

One of the many debated topics in inflammation research is whether this scenario is really an accelerated form of human wound healing and immunityboosting or a push towards autoimmune diseases. The answer requires a better understanding of the normal inflammatory process, including the molecular pathology underlying the possible outcomes. Exciting recent investigations regarding severe human inflammatory disorders and autoimmune conditions have implicated molecular changes that are also linked to normal immunity, such as triggering factors, switching on and off, the influence of other diseases and faulty stem cell homeostasis, in disease progression and development.

METHODS

We gathered around and collected recent online researches on immunity, inflammation, inflammatory disorders and AMPK. We basically searched PubMed, Scopus and Google Scholar to assemble the studies which were published since 2010.

RESULTS

Our findings suggested that inflammation and related disorders are on the verge and interfere in the treatment of other diseases. AMPK serves as a key component that prevents various kinds of inflammatory signaling. In addition, our table and hypothetical figures may open a new door in inflammation research, which could be a greater therapeutic target for controlling diabetes, obesity, insulin resistance and preventing autoimmune diseases.

CONCLUSION

The relationship between immunity and inflammation becomes easily apparent. Yet, the essence of inflammation turns out to be so startling that the theory may not be instantly established and many possible arguments are raised for its clearance. However, this study might be able to reveal some possible approaches where AMPK can reduce or prevent inflammatory disorders.

Circulating complement-1q tumor necrosis factor-α-related protein isoform 5 levels are low in type 2 diabetes patients and reduced by dapagliflozin

AIMS/INTRODUCTION

As a member of the tumor necrosis factor-α-related protein family, complement-1q tumor necrosis factor-α-related protein isoform 5 (CTRP5) has been found to be associated with obesity and insulin resistance (IR). Previous studies in humans and animals have reported contradictory results related to the association between CTRP5 and IR. The purpose of the present study was to explore the relationship between CTRP5 and IR through a cross-sectional study and drug intervention study of type 2 diabetes patients.

MATERIALS AND METHODS

A cross-sectional study was carried out with 118 newly diagnosed patients with type 2 diabetes and 116 healthy adults. In an interventional study, 78 individuals with newly diagnosed type 2 diabetes received sodium-glucose cotransporter 2 inhibitor (dapagliflozin) treatment for 3 months. Circulating CTRP5 concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

Serum CTRP5 concentrations were markedly reduced in patients with type 2 diabetes when compared with those of healthy individuals (P < 0.01). When considering the study population as a whole, individuals with IR (homeostasis model of assessment of IR ≥2.78) had lower CTRP5 concentrations than the individuals without IR (homeostasis model of assessment of IR <2.78; P < 0.01). Serum CTRP5 negatively correlated with age, body mass index, waist-to-hip ratio, Systolic blood pressure, triglyceride, total cholesterol, glycated hemoglobin, fasting blood glucose, 2-h blood glucose, fasting insulin and homeostasis model of assessment of IR. After 12 weeks of sodium-glucose cotransporter 2 inhibitor treatment, serum CTRP5 levels in type 2 diabetes patients were significantly reduced accompanied with ameliorated glycometabolism and IR compared with before treatment (P < 0.01).

CONCLUSIONS

CTRP5 is likely a marker for type 2 diabetes in humans.

Mitochondrial dysfunction, AMPK activation and peroxisomal metabolism: A coherent scenario for non-canonical 3-methylglutaconic acidurias

The occurrence of 3-methylglutaconic aciduria (3-MGA) is a well understood phenomenon in leucine oxidation and ketogenesis disorders (primary 3-MGAs). In contrast, its genesis in non-canonical (secondary) 3-MGAs, a growing-up group of disorders encompassing more than a dozen of inherited metabolic diseases, is a mystery still remaining unresolved for three decades. To puzzle out this anthologic problem of metabolism, three clues were considered: (i) the variety of disorders suggests a common cellular target at the cross-road of metabolic and signaling pathways, (ii) the response to leucine loading test only discriminative for primary but not secondary 3-MGAs suggests these latter are disorders of extramitochondrial HMG-CoA metabolism as also attested by their failure to increase 3-hydroxyisovalerate, a mitochondrial metabolite accumulating only in primary 3-MGAs, (iii) the peroxisome is an extramitochondrial site possessing its own pool and displaying metabolism of HMG-CoA, suggesting its possible involvement in producing extramitochondrial 3-methylglutaconate (3-MG). Following these clues provides a unifying common basis to non-canonical 3-MGAs: constitutive mitochondrial dysfunction induces AMPK activation which, by inhibiting early steps in cholesterol and fatty acid syntheses, pipelines cytoplasmic acetyl-CoA to peroxisomes where a rise in HMG-CoA followed by local dehydration and hydrolysis may lead to 3-MGA yield. Additional contributors are considered, notably for 3-MGAs associated with hyperammonemia, and to a lesser extent in CLPB deficiency. Metabolic and signaling itineraries followed by the proposed scenario are essentially sketched, being provided with compelling evidence from the literature coming in their support.

Role of Complement and Complement-Related Adipokines in Regulation of Energy Metabolism and Fat Storage

Adipose tissue releases many cytokines and inflammatory factors described as adipokines. In obesity, adipokines released from expanding adipose tissue are implicated in disease progression and metabolic dysfunction. However, mechanisms controlling the progression of adiposity and metabolic complications are not fully understood. It has been suggested that expanding fat mass and sustained release of inflammatory adipokines in adipose tissue lead to hypoxia, oxidative stress, apoptosis, and cellular damage. These changes trigger an immune response involving infiltration of adipose tissue with immune cells, complement activation and generation of factors involved in opsonization and clearance of damaged cells. Abundant evidence now indicates that adipose tissue is an active secretory source of complement and complement-related adipokines that, in addition to their inflammatory role, contribute to the regulation of metabolic function. This article highlights advances in knowledge regarding the role of these adipokines in energy regulation of adipose tissue through modulating lipogenic and lipolytic pathways. Several adipokines will be discussed including adipsin, Factor H, properdin, C3a, Acylation-Stimulating Protein, C1q/TNF-related proteins, and response gene to complement-32 (RGC-32). Interactions between these factors will be described considering their immune-metabolic roles in the adipose tissue microenvironment and their potential contribution to progression of adiposity and metabolic dysfunction. The differential expression and the role of complement factors in gender-related fat partitioning will also be addressed. Identifying lipogenic adipokines and their specific autocrine/paracrine roles may provide means for adipose-tissue-targeted therapeutic interventions that may disrupt the vicious circle of adiposity and disease progression. © 2019 American Physiological Society. Compr Physiol 9:1411-1429, 2019.