视黄醇结合蛋白4与胰岛素抵抗

脂肪组织是一个重要的内分泌器官.肥大的脂肪细胞分泌过量脂肪细胞因子,促进了胰岛素抵抗和糖尿病的发生、发展.视黄醇结合蛋白4(RBP4)主要由肝脏合成,负责维生素A的转运.新近研究发现,RBP4是一个新的脂肪细胞因子,与胰岛素抵抗相关疾病、体脂分布和糖尿病均有密切联系,它的发现为明确胰岛素抵抗发生机制提供了新的论据.     

视黄醇结合蛋白4与胰岛素抵抗

视黄醇结合蛋白4（RBP4）是一种主要来源于肝脏和脂肪细胞的转运蛋白。过去认为其作用是转运血液中的视黄醇（维生素A）。而近期的研究发现,RBP4作为一种脂质因子,可能具有引起胰岛素抵抗（IR）的作用,参与一系列与IR相关疾病,包括糖尿病、代谢综合征、非酒精性脂肪肝的发生发展。除外受到IR的影响,不同个体RBP4血清水平的影响因素各不相同。     

Retinol binding protein 4, low birth weight-related insulin resistance and hormonal contraception

It has been recently reported that increased serum levels of retinol binding protein 4 (RBP4), a molecule secreted by adipocytes and liver, could be an early marker of insulin resistance (IR). We determined whether serum RBP4 was increased in low birth weight (LBW)-young women as a model of early-onset IR, through a historical prospective study. The study-population included 35 LBW and 35 born at term appropriate for gestational age (term AGA) young women. Metabolic evaluations included the composite-insulin sensitivity index (composite ISI). Serum RBP4 was measured with a competitive enzyme-linked immunosorbent assay (ELISA). RBP4 levels were similar in LBW and term AGA women, while composite ISI was significantly lower in the former group. With multivariate logistic regression analysis hormonal contraception (HC) use but not birth weight, diabetes in either parents and body mass index was significantly associated with higher RBP4 levels: odds ratio = 10.6; 95% confidence interval (CI) = 2.4–76.6. In spite of higher RBP4 levels in women under HC, composite ISI was similar in women with or without HC. Women under HC also exhibited significantly higher levels of sex hormone binding globulin (SHBG), triglycerides, cholesterol, and C-reactive protein (CRP), and all of them, but not composite ISI, were significantly correlated with RBP4 levels. In conclusion, RBP4 serum level was not a marker of IR but, for the first time, it is documented a sustained increase of serum RBP4 under HC. Pathophysiological and clinical significance of this novel finding requires further investigations     

视黄醇结合蛋白4与糖尿病

肥胖和2型糖尿病关系十分密切,流行病学证据表明,肥胖是2型糖尿病的独立危险因素,而糖尿病与肥胖合并出现,是临床上常见的疾病聚集状态.肥胖和2型糖尿病存在一个共同的病理生理基础,即胰岛素抵抗.肥胖导致2型糖尿病的机制主要是脂肪组织内分泌失调和脂肪的异位沉积.     

脂联素与炎症及胰岛素抵抗关系的研究进展

胰岛素抵抗是由免疫系统介导的慢性、非特异性炎症过程。而脂联素具有抗炎、促炎的双重作用。其与炎症因子的相互作用可能是脂联素增强胰岛素敏感性的机制之一,也可能是胰岛素抵抗时低脂联素血症的原因。对脂联素与炎症、胰岛素抵抗关系的研究可为胰岛素抵抗的治疗提供新的思路。     

Human visfatin expression: relationship to insulin sensitivity, intramyocellular lipids, and inflammation

CONTEXT: Visfatin (VF) is a recently described adipokine preferentially secreted by visceral adipose tissue (VAT) with insulin mimetic properties. OBJECTIVE: The aim of this study was to examine the association of VF with insulin sensitivity, intramyocellular lipids (IMCL), and inflammation in humans. DESIGN AND PATIENTS: VF mRNA was examined in paired samples of VAT and abdominal sc adipose tissue (SAT) obtained from subjects undergoing surgery. Plasma VF and VF mRNA was also examined in SAT and muscle tissue, obtained by biopsy from well-characterized subjects with normal or impaired glucose tolerance, with a wide range in body mass index (BMI) and insulin sensitivity (S(I)). SETTING: The study was conducted at a University Hospital and General Clinical Research Center. INTERVENTION: S(I) was measured, and fat and muscle biopsies were performed. In impaired glucose tolerance subjects, these procedures were performed before and after treatment with pioglitazone or metformin. MAIN OUTCOME MEASURES: We measured the relationship between VF and obesity, S(I), adipose tissue inflammation, IMCL, and response to insulin sensitizers. RESULTS: No significant difference in VF mRNA was seen between SAT and VAT depots. VAT VF mRNA associated positively with BMI, whereas SAT VF mRNA decreased with BMI. SAT VF correlated positively with S(I), and the association of SAT VF mRNA with S(I) was independent of BMI. IMCL and markers of inflammation (adipose CD68 and plasma TNFalpha) were negatively associated with SAT VF. Impaired glucose tolerance subjects treated with pioglitazone showed no change in SAT VF mRNA despite a significant increase in S(I). Plasma VF and muscle VF mRNA did not correlate with BMI or S(I) or IMCL, and there was no change in muscle VF with either pioglitazone or metformin treatments. CONCLUSION: SAT VF is highly expressed in lean, more insulin-sensitive subjects and is attenuated in subjects with high IMCL, low S(I), and high levels of inflammatory markers. VAT VF and SAT VF are regulated oppositely with BMI.     

视黄醇结合蛋白4和心血管疾病危险因素

脂肪组织不仅是一个储备能量、提供能量的器官,更是重要的内分泌器官。2005年美国哈佛大学医学中心鉴定出一种新的参与胰岛素抵抗的脂肪细胞因子——视黄醇结合蛋白4（RetinolBindingprotein,RBP4）。随后多项研究表明其可诱导胰岛素抵抗,并且发现血浆RBP4水平在2型糖尿病、肥胖、代谢综合征以及心血管疾病中均有升高。同时国内外一些研究报道了它与脂质代谢、动脉粥样硬化、糖代谢、胰岛素抵抗、高血压、心力衰竭等心血管疾病相关危险因素的相关性。本文综述RBP4的结构、功能、测定及其在心血管疾病中的研究进展。     

Interrelationships between inflammation, C-reactive protein, and insulin resistance

The recognition that inflammation plays a fundamental role in atherothrombosis has led to the measurement of circulating inflammatory biomarkers such as high-sensitivity C-reactive protein (hs-CRP) as a means of improving cardiovascular disease detection and prevention. Clinically, levels of hs-CRP >3 mg/L indicate elevated risk for myocardial infarction and stroke, even among apparently healthy individuals with low-to-normal lipid levels. Emerging laboratory and epidemiologic data now link inflammation and hs-CRP to insulin resistance in that hs-CRP levels have been associated with impaired insulin sensitivity and the development of dysglycemic conditions, including the cardiometabolic syndrome and incident type 2 diabetes. hs-CRP has also been associated with each of the individual components of the cardiometabolic syndrome. Furthermore, in large prospective studies, hs-CRP adds prognostic information about cardiovascular risk beyond that provided by the cardiometabolic syndrome. These findings have led to discussion about the addition of hs-CRP measurement to the current definition of the cardiometabolic syndrome to improve detection of risk for both diabetes and cardiovascular events in patients. Multiple clinical studies are now underway that are evaluating whether agents traditionally used to improve glycemic control may also significantly reduce hs-CRP.     

大鼠肝脏组织视黄醇结合蛋白4在衰老过程中表达及与胰岛素抵抗的关系

目的:观察大鼠肝脏组织视黄醇结合蛋白4(retinol binding protein 4,RBP4)在衰老过程中表达差异,在分子水平上探讨衰老过程中出现胰岛素抵抗(insulin resistance,IR)的可能机制。方法:用Bergman创立的微小模型技术评价年轻鼠(8～12周龄)和老年鼠(24个月龄)的胰岛素敏感性,取大鼠肝脏组织提取总RNA,采用半定量RT-PCR法检测RBP4和过氧化体增殖物激活型受体α(peroxisomeproliferator-activated receptorα,PPARα)mRNA水平,用Western blot法检测RBP4和PPARα蛋白表达情况。结果:与年轻鼠组比较,老年鼠组存在明显的胰岛素抵抗,而老年鼠组的RBP4mRNA及蛋白表达明显升高,PPARαmRNA及蛋白表达明显减少。结论:衰老过程中大鼠肝脏组织RBP4表达升高可能与胰岛素抵抗有关。     

Mechanisms of insulin resistance in humans and possible links with inflammation

Insulin resistance is a major player in the pathogenesis of the metabolic syndrome and type 2 diabetes, and yet, the mechanisms responsible for it remain poorly understood. Magnetic resonance spectroscopy studies in humans suggest that a defect in insulin-stimulated glucose transport in skeletal muscle is the primary metabolic abnormality in insulin-resistant type 2 diabetics. Fatty acids appear to cause this defect in glucose transport by inhibiting insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and IRS-1 associated phosphatidylinositol 3-kinase activity. A number of different metabolic abnormalities may increase intramyocellular/intrahepatic fatty acid metabolites; these include increased fat delivery to muscle/liver as a consequence of either excess energy intake or defects in adipocyte fat metabolism and acquired or inherited defects in mitochondrial fatty acid oxidation. Understanding the molecular/biochemical defects responsible for insulin resistance is beginning to unveil novel therapeutic targets for treatment of the metabolic syndrome and type 2 diabetes.     

Adipose triglyceride lipase expression in human adipose tissue and muscle. Role in insulin resistance and response to training and pioglitazone

Adipose triglyceride lipase (ATGL) catalyzes the first step in adipocyte and muscle triglyceride hydrolysis, and comparative gene identification-58 (CGI-58) is an essential cofactor. We studied the expression of ATGL and CGI-58 in human adipose and muscle and examined correlations with markers of muscle fatty acid oxidation. Nondiabetic volunteers were studied. Subjects with impaired glucose tolerance were treated with pioglitazone or metformin for 10 weeks. Subjects with normal glucose tolerance underwent a 12-week training program. We examined changes in ATGL and CGI-58 with obesity and insulin resistance, and effects of exercise and pioglitazone. Adipose triglyceride lipase messenger RNA (mRNA) expression showed no correlation with either body mass index or insulin sensitivity index in either adipose or muscle. However, adipose ATGL protein levels were inversely correlated with body mass index (r = −0.64, P < .02) and positively correlated with insulin sensitivity index (r = 0.67, P < .02). In muscle, ATGL mRNA demonstrated a strong positive relationship with carnitine palmitoyltransferase I mRNA (r = 0.82, P < .0001) and the adiponectin receptors AdipoR1 mRNA (r = 0.71, P < .0001) and AdipoR2 mRNA (r = 0.74, P < .0001). Muscle CGI-58 mRNA was inversely correlated with intramyocellular triglyceride in both type 1 (r = −0.35, P < .05) and type 2 (r = −0.40, P < .05) fibers. Exercise training resulted in increased muscle ATGL, and pioglitazone increased adipose ATGL by 31% (P < .05). Pioglitazone also increased ATGL in adipocytes. Adipose ATGL protein is decreased with insulin resistance and obesity; and muscle ATGL mRNA is associated with markers of fatty acid oxidation in muscle, as is CGI-58. The regulation of ATGL and CGI-58 has important implications for the control of lipotoxicity.     

衰老大鼠脂肪组织视黄醇结合蛋白4表达及与胰岛素抵抗关系的研究

目的探讨年轻及衰老大鼠脂肪组织视黄醇结合蛋白4（retinol binding protein4,RBP4）表达水平的变化及与胰岛素抵抗（insulin resistance,IR）的关系。方法用Bergman创立的微小模型技术评价年轻鼠（8～12周龄）和老年鼠（24个月龄）的胰岛素敏感性,取大鼠大网膜脂肪组织提取总RNA,采用半定量RT-PCR法检测RBP4,用Western blot法检测RBP4蛋白表达情况。结果与年轻鼠组比较,老年鼠组存在明显的胰岛素抵抗,而老年鼠组的RBP4 mRNA及蛋白表达明显升高,RBP4表达与胰岛素敏感指数呈负相关。结论衰老过程中大鼠脂肪组织RBP4表达升高可能与胰岛素抵抗有关。     

Obesity, inflammation, and insulin resistance

Weight gain and obesity are major risk factors for conditions and diseases ranging from insulin resistance and type 2 diabetes mellitus to atherosclerosis and the sequelae of nonalcoholic fatty liver disease. A chronic, subacute state of inflammation often accompanies the accumulation of excess lipid in adipose tissue and liver (hepatic steatosis), evidenced by changes in both inflammatory cells and biochemical markers of inflammation. These changes can be seen in the involved tissues and systemically, in terms of elevated circulating levels of inflammatory markers. The link between obesity and inflammation has therefore raised the important question of whether obesity-induced inflammation plays a pathogenic role in the development and progression of these disorders. We review the rapidly expanding body of animal and clinical data that support potential roles for inflammation in the pathogenesis of insulin resistance and type 2 diabetes mellitus.     

视黄醇结合蛋白4与多囊卵巢综合征及妊娠糖尿病

视黄醇结合蛋白4主要由肝脏合成,是血液中一种运送视黄醇的结合蚩白,亦是脂肪组织分泌的一种脂肪细胞因子.小鼠实验发现,其在组织中的过度表达可使磷脂酰肌醇3激酶活性下降,胰岛素受体底物1酪氨酸磷酸化降低.可能与胰岛素抵抗的发生有关.肥胖、糖耐量减低、胰岛素抵抗、多囊卵巢综合征、妊娠糖尿病患者血清中视黄醇结合蛋白4含量与正常者相比升高,其可能与此类疾病的发病机制有关.     

Association of serum retinol binding protein 4 and insulin resistance in apparently healthy adolescents

Insulin resistance constitutes a pathophysiologic link between obesity, atherosclerosis, and/or cardiovascular complications. Retinol binding protein 4 (RBP4) is a newly discovered adipocyte product that modulates glucose metabolism and consequently induces insulin resistance. We investigated the association between serum RBP4 levels and insulin resistance in obese and nonobese adolescents. A total of 87 nonobese (60 males and 27 females) and 85 obese (62 males and 23 females) apparently healthy adolescents, 12 to 18 years old, were included in this study. A questionnaire was used to obtain participant medical history and lifestyle information, such as smoking and alcohol ingestion habits. Subjects' anthropometric measurements were taken to calculate for body mass index and waist-to-hip ratio. Serum RBP4 levels were measured by an enzyme immunoassay kit. High-sensitivity C-reactive protein, fasting glucose, total cholesterol, triglycerides, high-density lipoprotein cholesterol, and fasting insulin were measured. Low-density lipoprotein cholesterol level and homeostatic model assessment of insulin resistance (HOMA-IR) were calculated. Males had significantly higher RBP4 levels than females. Serum RBP4 levels were significantly higher in the obese group compared with the nonobese group. In all subjects, RBP4 was positively correlated with adiposity index (body mass index, waist circumference, waist-to-hip ratio), systolic and diastolic blood pressures, glucose tolerance index (fasting glucose, insulin, HOMA-IR), lipid profile (total cholesterol, triglycerides), and inflammatory indices (high-sensitivity C-reactive protein, white blood cell count). In multiple linear regression analysis, RBP4 was independently associated with age, HOMA-IR, and triglyceride levels in the nonobese group and with sex and triglyceride levels in the obese group. These results suggest that serum RBP4 might have clinical implications for lipid metabolism and insulin action in adolescents.     

培哚普利及氨氯地平联合治疗对原发性高血压患者自主神经功能及胰岛素抵抗和血清视黄醇结合蛋白4表达的影响

目的:探讨培哚普利与氨氯地平联合治疗对原发性高血压患者自主神经功能、胰岛素抵抗及血清视黄醇结合蛋白4(RBP4)表达的影响。方法:选择2016年2月至2017年9月,在我院接受治疗的老年原发性高血压患者87例进行研究,采用随机数字表法将其随机分为对照组43例和联合组44例。对照组给予氨氯地平治疗,联合组同时给予培哚普利治疗,连续治疗8周。比较两组患者治疗效果及治疗前后心率变异(HRV)、血压(BPV)指标、胰岛素抵抗指数(HOMA-IR)及血清RBP4水平变化情况,比较两组患者治疗过程中不良反应发生情况。结果:连续治疗8周后,联合组总有效率为95.5%,显著高于对照组的76.7%(χ~2=6.403,P=0.011);治疗后联合组患者的SDNN、SDANN、RMSSD、PNN50、SDNNindex等HRV各项指标均显著高于对照组(P0.05);联合组治疗后HOMA-IR(24.48±6.16) mg/L,显著低于对照组的(27.39±5.92) mg/L(t=2.246,P=0.027),血清RBP4(3.94±0.89)g/mL,也显著低于对照组的(4.52±0.92)g/mL(t=2.989,P=0.004);治疗期间联合组不良反应发生率为11.4%(5/44),与对照组的9.3%(4/43)比较,差异无统计学意义(χ~2=0.100,P=0.752)。结论:培哚普利联合氨氯地平治疗老年原发性高血压效果显著,其可显著提升患者的心率变异性,降低胰岛素抵抗,这一作用可能是通过降低血清RBP4水平实现的,同时不会增加不良反应的发生,安全性高,值得临床推广应用。