Circulatory changes of the novel adipokine adipolin/CTRP12 in response to metformin treatment and an oral glucose challenge in humans

Effects of Metformin on CIMT and FMD in PCOS patients: a systematic review and meta-analysis

BACKGROUND

This study aims to analyze the efficacy of metformin on carotid intima media thickness (CIMT) and flow-mediated dilation (FMD) for patients with polycystic ovary syndrome (PCOS).

METHODS

A literature search of PubMed, Embase, and the Cochrane Library from inception to December 2023 was conducted. Then, after studies selection and data extraction, the mean difference (MD) with a 95% confidence interval (CI) was used to evaluate metformin efficacy in CIMT and FMD for PCOS patients. Heterogeneity was investigated through subgroup and sensitivity analysis. The protocol of our study has been registered in PROSPERO (CRD42024497239).

RESULTS

A total of 12 studies with 248 patients were included. CIMT was lower in the endpoint group (after metformin) compared with the baseline group (before metformin) (MD = -0.11, 95% CI = -0.21 to -0.01, p = 0.04). FMD was higher in the endpoint group compared with the baseline group (MD = 3.25, 95% CI = 1.85 to 4.66, p < 0.01). No statistically significant difference was observed in nitroglycerin-mediated dilation (NMD) between the two groups (MD = 0.65, p = 0.51). Subgroup analysis showed that a relatively lower MD of CIMT in PCOS patients from Europe in the endpoint group compared with the baseline group (MD = -0.09, 95% CI = -0.14 to -0.04, p < 0.001). However, the MD in CIMT was not significantly different between the endpoint group and baseline group in PCOS patients from Asia (p = 0.270).

CONCLUSION

Metformin may have a beneficial effect on CIMT and FMD, but not on NMD, suggesting that metformin may help reduce cardiovascular events in PCOS patients. Notably, the clinical efficacy of metformin can be influenced by regional differences and study types.

Possible Effect of Polycystic Ovary Syndrome (PCOS) on Cardiovascular Disease (CVD): An Update

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women during the fertile period. Women with PCOS have an increased risk of developing major cardiovascular risk factors during the fertile period: obesity, impaired glucose tolerance, diabetes mellitus, dyslipidemia, and metabolic syndrome. The possible effect of PCOS on cardiovascular disease (CVD) has been reported in different studies, but the results are not clear for several reasons. Indeed, most of the studies analyzed a cohort of fertile women who, given their relatively young age, have a low frequency of cardiovascular diseases. In addition, longitudinal studies have a short follow-up period, insufficient to draw firm conclusions on this topic. Finally, pharmacological treatment is limited by the lack of specific drugs available to specifically treat PCOS. In this review, we report on studies that analyzed the possible effect of PCOS on the most common CVD (hypertension, arterial stiffness, atherosclerosis, and cardiovascular event) and available drugs used to reduce CVD in PCOS women.

Cumulative effects of exercise training and consumption of propolis on managing diabetic dyslipidemia in adult women: a single-blind, randomized, controlled trial with pre-post-intervention assessments

Dyslipidemia is an imbalance of various lipids, and propolis, as a natural resinous viscos mixture made by Apis mellifera L. could improve in this condition. In this single-blind, randomized trial, 60 women with type 2 diabetes and dyslipidemia were divided into four groups: (1) the patients who did not apply the combined training and 500 mg propolis capsules supplement (Control group); (2) subjects performed combined training, including aerobic and resistance training (EXR); (3) subjects received the 500 mg propolis supplement capsules (SUPP); (4) Subjects performed combined training along with receiving the 500 mg propolis supplement capsules (EXR + SUPP). We evaluated the concentration of CTRP12, SFRP5, interleukin-6 (IL6), superoxide dismutase (SOD), malondialdehyde (MDA), adiponectin, and total antioxidant capacity (TAC) before and after the intervention. MDA, TAC, IL6, CTRP12, SFRP5 IL6, adiponectin, and lipid profile levels ameliorated in the EXR + SUPP group. We found that 8 weeks of treatment by combined exercise training and propolis supplement decreased inflammation activity and increased antioxidant defense in women with diabetic dyslipidemia.Trial registration This study was registered in the Iranian Registry of Clinical Trials; IRCT code: IRCT20211229053561N1.

Adipolin and IL-6 Serum Levels in Chronic Obstructive Pulmonary Disease

Objective(s): One of the adipokines that have insulin-sensitizing properties is adipolin, whose reduced levels have been reported in obesity, oxidative stress, and inflammation. The present study investigated serum interleukin-6 (IL-6) and adipolin levels in chronic obstructive pulmonary disease (COPD) patients. Method: A control case study included 60 COPD patients and 30 healthy subjects in the research and measured adipolin and IL-6 serum levels. In addition, serum adipolin levels in COPD patients were assessed according to the GOLD grade. The relationship between serum adipolin levels and study variables were also analyzed. Results: The results showed reduced adipolin levels in COPD patients compared with healthy individuals (p < 0.001). Furthermore, increased levels of IL-6 were evident in the COPD group compared to the control group (p < 0.001). Adipolin serum levels were positively correlated with PFTs and negatively correlated with IL-6 levels. Conclusion: Decreased adipolin levels enhanced disease severity in COPD patients. It seems that the existence of a significant relationship between adipolin and IL-6 may indicate the role of adipolin in the pathophysiology of COPD.

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.

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

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

Metabolic Syndrome: the Influence of Adipokines on the L-Arginine-NO Synthase-Nitric Oxide Signaling Pathway

Metabolic syndrome includes the following symptoms: obesity, hyperlipidemia, hypertension, insulin resistance, and cardiovascular disease. The purpose of this review is to elucidate the role of adipokines in the regulation of the L-arginine-NO-synthas-NO signaling pathway in the pathogenesis of metabolic syndrome. The main questions raised in the review are: how adipokine secretion changes, how the level of their receptors is regulated, and which signaling pathways are involved in the transmission of adipokine signals when coupled to the L-arginine-NO-synthase-NO signaling cascade. Adipokines are peptide hormones that transmit a signal from adipose tissue to targets in the brain, blood vessels, liver, pancreas, muscles, and other tissues. Some adipokines have anti-inflammatory and insulin-sensitive effects: adiponectin, omentin, adipolin, chemerin, progranulin. Others have the negative inflammatory effect in the development ofmetabolic syndrome: visfatin, vaspin, apelin. Adipokines primarily regulate the expression and activity of endothelial NO-synthase. They either activate an enzyme involving 5-AMP protein kinase or Akt kinase, increasing its activity and synthesis of NO in the tissues of healthy patients: adiponectin, adipolin, omentin, or inhibit the activity of eNOS, which leads to a decrease in NO-synthase and suppression of mRNA bioavailability: vaspin, visfatin, apelin in metabolic syndrome, and a decrease in its activity leads to dissociation and endothelial dysfunction. It should be noted that the bioavailability of NO formed by NO-synthase is affected at many levels, including: the expression ofNO-synthase mRNA and its protein; the concentration of L-arginine; the level of cofactors of the reaction; and to detect the maximum activity of endothelial NO-synthase, dimerization of the enzyme is required, posttranslational modifications are important, in particular, phosphorylation of endothelial NO-synthase by serine 1177 with the participation of 5-AMP protein kinase, Akt kinase and other kinases. It should be noted that the participation of adiponectin, omentin, and kemerin in the regulation of the L-arginine-NO-synthase-NO cascade in metabolic syndrom opens up certain opportunities for the development of new approaches for the correction of disorders observed in this disease. The review analyzes the results of research searching in PubMed databases, starting from 2001 and up to 2020 using keywords and adipokine names, more than half of the references of the last 5 years. 

CTRP12 Alleviates Isoproterenol Induced Cardiac Fibrosis via Inhibiting the Activation of P38 Pathway

C1q/tumor necrosis factor (TNF)-related protein 12 (CTRP12) plays a crucial part in cardiovascular diseases especially the coronary artery disease. Nonetheless, it is unrevealed that whether the CTRP12 participates in the progress of cardiac fibrosis. In this study, we investigated whether CTRP12 regulates pathological myocardial fibrosis. We isolated neonatal rat cardiac fibroblasts were cultured with recombination CTRP12 followed by stimulating with Isoproterenol (ISO, 100 µM) for 24 h. Then the adenovirus were used to achieve the CTRP12-overexpressed fibroblasts. In vivo, the C57/B6 mice were subjected to recombinant human CTRP12 (0.2 µg/g/d) for 2 weeks after injected with Isoproterenol (ISO, 10 mg/kg/d for 3 d then 5 mg/kg/d for 11 d, subcutaneously (s.c.), 2 weeks) and mice were also subjected to adenovirus with P38 overexpressing system to explore the mechanism. As a result, CTRP12 significantly inhibit the transformation of cardiac fibroblasts to myofibroblasts and the transcription of cardiac fibrosis-related proteins induced by ISO in vitro. The administration of CTRP12 can effectively reduce the cardiac fibrosis and enhance the cardiac function in mice hearts. The treatment with CTRP12 did not change the expression level of phosphorylated (p)-smad2, smad4, p-extracellular regulated protein kinases 1/2 and c-Jun N-terminal kinase 1/2, but it suppressed the activation of p38. Cardiac overexpression of p38 could abolish this kind of cardioprotective effects by CTRP12. In summary, the CTRP12 protect against the ISO induced cardiac fibrosis via suppressing the p38 signal pathway.

Assessment of Early Markers of Cardiovascular Risk in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a heterogeneous syndrome, with long-term sequelae from birth to senescence. The long-term effects of PCOS are attributed to several metabolic aberrations ensuing the syndrome. In a systematic review of literature regarding the cardiovascular risk factors that accompany PCOS, we found that macrovascular function has been assessed by flow-mediated dilatation (FMD), microvascular function by venous occlusion plethysmography (VOP), and arterial structure by ultrasonographic assessment of intima-media thickness (IMT) usually of the carotid artery. Contradictory results have been reported; however, in most studies, endothelial dysfunction, an early marker of atherosclerosis assessed either by haemodynamic methods such as FMD or by biochemical methods such as endothelin-1 levels, was found to be impaired. VOP is a less-studied method, with few indices altered. IMT was found to be altered in most of the included studies, but the population was more heterogeneous. Inflammatory markers, including C-reactive protein, were also found to be altered in most studies. On the other hand, a number of interventions have been shown beneficial for the markers of cardiovascular risk, in the context of insulin-sensitizers. However, other interventions such as oral contraceptive pills or statins did not consistently show a similar beneficial effect. In summary, the early identification and eventual treatment of cardiovascular clinical and biochemical risk factors may be used in clinical practice to prevent potential 'silent' triggers of cardiovascular disease.

Integration of lncRNA and mRNA profiles to reveal the protective effects of Codonopsis pilosula extract on the gastrointestinal tract of mice subjected to D‑galactose‑induced aging

Codonopsis pilosula is a type of traditional Chinese medicine that exerts an anti‑aging effect and can regulate the gastrointestinal (GI) system. The aim of the present study was to investigate the underlying molecular mechanisms responsible for the anti‑aging effects of Codonopsis pilosula in the GI tract of mice with D‑galactose‑induced aging. First, a successful mouse model of aging was established, and Codonopsis pilosula water extract was then used for treatment. The anti‑aging effects of Codonopsis pilosula on the GI tract were then detected from the perspectives of tissue structure, physiological function and cell ultrastructure. Finally, in order to explore the underlying molecular mechanisms, the expression profiles of lncRNAs and mRNAs in the stomach and intestine were examined using microarray technology. A total of 117 (41 lncRNAs and 76 mRNAs) and 168 (85 lncRNA sand 83 mRNAs) differentially expressed genes associated with the anti‑aging effects of Codonopsis pilosula were identified in the stomach and intestine, respectively. Through integrated analysis of the stomach and intestine, 4 hub RNAs, including 1 lncRNA (LOC105243318) and 3 mRNAs (Fam132a, Rorc and 1200016E24Rik) were identified, which may be associated with the anti‑aging effects of Codonopsis pilosula in the GI tract of aging mice. The Kyoto Encyclopedia of Genes and Genomes analysis revealed that the metabolic pathway was an important pathway underlying the anti‑aging effects of Codonopsis pilosula in the GI tract. On the whole, in the present study, 4 hub RNAs associated with these effects and their regulatory networks were found in the GI tract of aging mice. In addition, the metabolic pathway was found to play an important role in these anti‑aging effects in the GI tract.

Assessment of Early Markers of Cardiovascular Risk in Polycystic Ovary Syndrome

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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.

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.

N-Linked Glycosylation-Dependent and -Independent Mechanisms Regulating CTRP12 Cleavage, Secretion, and Stability

C1q/TNF-related protein 12 (CTRP12) is a secreted regulator of glucose and lipid metabolism. It circulates in plasma as a full-length protein or as a cleaved isoform generated by furin/PCSK3 cleavage. These isoforms preferentially activate different signaling pathways, and their ratio in plasma is altered in obesity and diabetes. Here, we show that three conserved asparagine residues (Asn-39, Asn-287, and Asn-297) play important roles in modulating CTRP12 cleavage, secretion, and stability. Mass spectrometry analysis provided direct evidence of Asn-39 glycosylation. When N-linked glycosylation was inhibited by tunicamycin or abolished by the N39Q, N39A, or T41A mutation, CTRP12 cleavage was enhanced. Complex-type N-glycans on CTRP12 blocked cleavage by the Golgi-localized furin. In N-acetylglucosaminyltransferase I (GnTI)-deficient cells that could not form hybrid and complex-type N-glycans in the Golgi, CTRP12 cleavage was enhanced, and re-expressing GnTI reduced cleavage. Replacing the nonglycosylated Asn-297 with glutamine or alanine also increased CTRP12 cleavage. Both Asn-39 and Asn-297 contributed independently to CTRP12 cleavage: maximum cleavage was observed in the double mutant. In addition, CTRP12 cleavage was abolished in furin-deficient cells and restored by furin re-expression. Replacing the nonglycosylated Asn-287 with glutamine or alanine resulted in protein misfolding and aggregation, leading to retention in the endoplasmic reticulum. Cycloheximide chase analyses indicated reduced protein stability for N39Q, T41A, and N297Q mutants. Lastly, we show that increasing the flux through the hexosamine biosynthesis pathway by exogenous glucosamine, known to disrupt protein glycosylation, also promoted CTRP12 cleavage. Combined, these data highlight glycosylation-dependent and -independent mechanisms regulating CTRP12 cleavage, secretion, and protein stability.

Lower circulating levels of CTRP12 and CTRP13 in polycystic ovarian syndrome: Irrespective of obesity

Altered production of adipokines is suggested to play a pivotal role in the pathogenesis of polycystic ovarian syndrome (PCOS). C1q/TNF-related proteins (CTRPs) play diverse roles in regulation of metabolism in physiologic and pathologic conditions. In the present study, we assessed serum concentrations of adiponectin, CTRP12, and CTRP13 in individuals with PCOS and those without PCOS. We also evaluated the possible association of these adipokines with metabolic and hormonal variables. A total of 171 premenopausal women (86 with PCOS and 85 without PCOS) enrolled in this study. Serum levels of adiponectin, CTRP12, and CTRP13 were measured. The results showed significantly lower serum concentrations of adiponectin, CTRP12, and CTRP13 in PCOS women compared to non-PCOS women. This difference remained significant after controlling for age, body mass index (BMI), and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). However, we did not observe any significant differences in serum levels of adiponectin, CTRP12, and CTRP13 between the overweight/obese and normal weight subgroups in PCOS and non-PCOS women. Multiple linear regression analysis showed associations of CTRP12 with adiponectin and BMI with CTRP13 in both the PCOS and non-PCOS groups. CTRP12 was significantly associated with BMI and adiponectin in the non-PCOS group, and fasting blood glucose (FBG) and CTRP13 in the PCOS group. Our results indicated that decreased adiponectin, CTRP12, and CTRP13 levels, regardless of obesity, could independently predict PCOS. This finding suggested a novel link between adipokines and PCOS.

The role of adiponectin and adipolin as anti-inflammatory adipokines in the formation of macrophage foam cells and their association with cardiovascular diseases

Obesity is one of the major public health concerns that is closely associated with obesity-related disorders such as type 2 diabetes mellitus (T2DM), hypertension, and atherosclerosis. Atherosclerosis is a chronic disease characterized by excess cholesterol deposition in the arterial intima and the formation of foam cells. Adipocytokines or adipokines are secreted by the adipose tissue as endocrine glands; adiponectin and adipolin are among these adipokines that are associated with obese and insulin-resistant phenotypes. Adipolin and adiponectin are cytokines that exert substantial impact on obesity, progression of atherosclerosis, insulin resistance, and glucose metabolism. In this paper, we review the formation of macrophage foam cells, which are associated with atherosclerosis, and the macrophage mechanism, which includes uptake, esterification, and release. We also summarize current information on adipose tissue-derived hormone and energy homeostasis in obesity. Finally, the role of adipokines, e.g., adipoline and adiponectin, in regulating metabolic, cardiovascular diseases is discussed.

Circulating C1q complement/TNF-related protein (CTRP) 1, CTRP9, CTRP12 and CTRP13 concentrations in Type 2 diabetes mellitus: In vivo regulation by glucose

OBJECTIVES

The C1q complement/TNF-related protein (CTRP) superfamily, which includes the adipokine adiponectin, has been shown in animal models to have positive metabolic and cardiovascular effects. We sought to investigate circulating CTRP1, CTRP9, CTRP12 and CTRP13 concentrations in persons with type 2 diabetes mellitus (T2DM), with age and BMI matched controls, and to examine the effects of a 2 hour 75g oral glucose tolerance test (OGTT) on serum CTRP1, CTRP9, CTRP12 and CTRP13 levels in persons with T2DM.

DESIGN

Cross-sectional study [newly diagnosed T2DM (n = 124) and control (n = 139) participants]. Serum CTRP1, CTRP9, CTRP12 and CTRP13 were measured by ELISA.

RESULTS

Systolic and diastolic blood pressure, total cholesterol (TCH), Low-density lipoprotein (LDL)-cholesterol, triglycerides, TCH/High-density lipoprotein (HDL) ratio, triglycerides/HDL ratio, glucose, insulin, homeostatic model assessment-insulin resistance (HOMA-IR), C-reactive protein and endothelial lipase were significantly higher, whereas leptin and adiponectin were significantly lower in T2DM participants. Serum CTRP1 were significantly higher and CTRP12 significantly lower in T2DM participants. Age, diastolic blood pressure, glucose and CTRP12 were predictive of serum CTRP1; leptin was predictive of serum CTRP9; glucose and CTRP1 were predictive of serum CTRP12; endothelial lipase was predictive of serum CTRP13. Finally, serum CTRP1 were significantly higher and CTRP12 significantly lower in T2DM participants after a 2 hour 75g OGTT.

CONCLUSIONS

Our data supports CTRP1 and CTRP12 as potential novel biomarkers for the prediction and early diagnosis of T2DM. Furthermore, pharmacological agents that target CTRP1 and CTRP12 could represent a new strategy in the treatment of T2DM.

Association of C1q/TNF-Related Protein-3 (CTRP3) and CTRP13 Serum Levels with Coronary Artery Disease in Subjects with and without Type 2 Diabetes Mellitus

C1q/TNF-Related Protein-3 (CTRP3) and CTRP13 are two newly discovered adipokines regulating glucose and lipid metabolism. But their role in type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD) is still in infancy. The aim of this study was to investigate the associations of gene expression and serum levels of CTRP3 and CTRP13 with CAD, metabolic and inflammatory markers in patients with and without T2DM. Serum levels of CTRP3, CTRP13, adiponectin and inflammatory cytokines and their gene expression in peripheral blood mononuclear cells (PBMCs) were determined in 172 subjects categorized as group I (without T2DM and CAD), group II (with CAD but no T2DM), group III (with T2DM but no CAD) and group IV (with T2DM and CAD). Serum levels and gene expression of CTRP3, CTRP13 and adiponectin in the group I were higher compared to other groups. Inflammatory cytokines in the control group were lower than other groups too. CTRP3 serum levels have an independent association with BMI, smoking and CTRP3 gene expression; also CTRP13 serum levels has an independent association with BMI, HDL-C, insulin, HOMA-IR, HbA1c and TNF-α. Decreased serum levels of CTRP3 and CTRP13 were also associated with CAD. It appears that the decreased levels of CTRP3 and especially CTRP13 were associated with increased risk of T2DM and CAD. These findings suggest an emerging role of these adipokines in the pathogenesis of CAD, but further studies are necessary to establish this concept.

Partial deficiency of CTRP12 alters hepatic lipid metabolism

Secreted hormones play pivotal roles in tissue cross talk to maintain physiologic blood glucose and lipid levels. We previously showed that C1q/TNF-related protein 12 (CTRP12) is a novel secreted protein involved in regulating glucose metabolism whose circulating levels are reduced in obese and insulin-resistant mouse models. Its role in lipid metabolism, however, is unknown. Using a novel heterozygous mouse model, we show that the loss of a single copy of the Ctrp12 gene (also known as Fam132a and adipolin) affects whole body lipid metabolism. In Ctrp12 (+/-) male mice fed a control low-fat diet, hepatic fat oxidation was upregulated while hepatic VLDL-triglyceride secretion was reduced relative to wild-type (WT) littermates. When challenged with a high-fat diet, Ctrp12 (+/-) male mice had impaired lipid clearance in response to acute lipid gavage, reduced hepatic triglyceride secretion, and greater steatosis with higher liver triglyceride and cholesterol levels. Unlike male mice, Ctrp12 (+/-) female mice fed a control low-fat diet were indistinguishable from WT littermates. When obesity was induced by high-fat feeding, Ctrp12 (+/-) female mice developed mild insulin resistance with impaired insulin tolerance. In contrast to male mice, hepatic triglyceride secretion was increased in Ctrp12 (+/-) female mice fed a high-fat diet. Thus, in different dietary and metabolic contexts, loss of a single Ctrp12 allele affects glucose and lipid metabolism in a sex-dependent manner, highlighting the importance of genetic and environmental determinants of metabolic phenotypes.

Adipose Tissue as an Endocrine Organ: An Update on Pro-inflammatory and Anti-inflammatory Microenvironment

Adipose tissue is recognized as an active endocrine organ that produces a number of endocrine substances referred to as "adipokines" including leptin, adiponectin, adipolin, visfatin, omentin, tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), resistin, pigment epithelium-derived factor (PEDF), and progranulin (PGRN) which play an important role in the food intake regulation and significantly influence insulin sensitivity and in some cases directly affect insulin resistance in skeletal muscle, liver, and adipose tissue. The review summarizes current knowledge about adipose tissue-derived hormones and their influence on energy homeostasis regulation. The possible therapeutic potential of these adipokines in the treatment of insulin resistance, endothelial dysfunction, a pro-inflammatory response, obesity, eating disorders, progression of atherosclerosis, type 1 diabetes, and type 2 diabetes is discussed.