脂联素调节糖脂代谢相关信号通路的研究进展

脂联素是一种主要由脂肪组织分泌的脂肪细胞因子,具有调节糖脂代谢、增强胰岛素敏感性、抗炎和抗动脉粥样硬化等多种作用。在脂联素介导的信号通路中,脂联素首先与脂联素受体(AdipoR)位于膜外的羧基端结合,再通过AdipoR膜内的氨基端与信号接头蛋白结合,进而激活下游的多条信号通路,其中腺苷酸活化蛋白激酶(AMPK)是脂联素信号通路中的关键分子,活化的AMPK可以使其下游的乙酰辅酶A羧化酶(ACC)、p38丝裂原活化蛋白激酶(p38 MAPK)、磷脂酰肌醇3激酶(PI3K)等多种胞质信号分子磷酸化,介导细胞能量代谢。本文重点综述了脂联素通过AMPK调节糖脂代谢的信号通路的研究进展。     

瘦素对骨关节炎影响的研究进展

瘦素(Leptin)是脂肪因子的一种,可以在骨关节炎(OA)患者的血浆、滑液、软骨中被检测到。OA是一种最常见的关节疾病,其可以发生于全身的多个关节,以骨质和滑膜组织新陈代谢的改变、关节软骨的破坏和由此引起的关节软骨的减少为特征。瘦素是一种由肥胖(0b)基因编码的一个小的非糖基化肽激素。最开始,瘦素仅仅被认为是一种脂肪细胞源性的小分子(16KD),在下丘脑中枢水平作为一个饱感因子介导食物摄入量减少,并增加能量的消耗。现在已经发现,瘦素在机体内可发挥多种生理作用,并与OA病情有关。本文通过对瘦素与OA、软骨、肥胖、生物标志物、脂联素等之间的联系做一综述,以了解瘦素与OA之间的联系,为OA的治疗方面的进一步研究提供帮助。     

瘦素-脂联素比值：代谢健康中的可靠指标

瘦素-脂联素比值(leptin-adiponectin ratio, LAR)将瘦素的促炎和胰岛素抵抗作用与脂联素的抗炎和胰岛素增敏特性相结合,是一种可以反映有关胰岛素敏感性、脂肪组织功能障碍和心血管健康的可靠指标。在临床应用中,LAR表现出在评估胰岛素抵抗、诊断代谢综合征、衡量心血管风险方面的潜力,与多种疾病密切相关。它的应用范围涵盖了从儿童、青年到老年人的多个年龄段及孕妇等特殊生理状态。该文提供了LAR作为评估代谢健康的新兴生物标志物的强有力证据,同时指出了当前的挑战和限制,旨在为相关疾病的病情评估、疾病进展、疗效观察以及临床预后的判断等提供科学依据。     

高脂饮食及运动对2型糖尿病大鼠脂联素、瘦素及血糖水平的影响

目的：观察高脂饮食及运动对糖尿病大鼠脂联素、瘦素及血糖水平的影响。方法：选取SD清洁大鼠80只,雌雄各半,随机分为5组（n=16）：空白对照组（A）,普通饮食组（B）,高脂饮食组（C）,普通饮食干预组（普通饮食+运动干预,D）,高脂饮食干预组（高脂饮食+运动干预,E）;除空白组外,其余四组均给予高糖高脂饲料喂养6周后,腹腔链脲佐菌素（30 mg/kg）制备2型糖尿病模型（T2DM）;大鼠建模后,空白组、普通饮食组及普通饮食干预组给予常规饲料,高脂组及高脂饮食干预组大鼠给予高脂饲料,普通饮食干预组及高脂饮食干预组给予运动干预,采用滚筒训练器进行运动,运动频率为每天1次,每周6次,持续6周。6周后测量大鼠脂联素、瘦素、血糖及相关生化指标。结果：除空白组外,其余四组大鼠实验后脂联素水平明显降低（P<0.05）、瘦素、血糖、糖化血红蛋白、甘油三酯明显升高（P<0.05）;高脂饮食组大鼠瘦素、血糖、糖化血红蛋白、甘油三酯水平明显高于高脂饮食干预组（P<0.01）;高脂饮食干预组大鼠瘦素、血糖、糖化血红蛋白、甘油三酯水平高于普通饮食组（P<0.05）;普通饮食组瘦素、血糖、糖化血红蛋白、甘油三酯水平高于普通饮食干预组（P<0.05）;T2DM大鼠模型各组瘦素、血糖、糖化血红蛋白、甘油三酯水平均明显高于对照组（P<0.01）。高脂饮食组大鼠脂联素水平明显低于高脂饮食干预组（P<0.01）;高脂饮食干预组脂联素水平低于普通饮食组（P<0.05）;普通饮食组脂联素水平低于普通饮食干预组（P<0.05）;T2DM大鼠模型各组脂联素水平均明显低于对照组（P<0.01）。脂联素与血糖,瘦素与血糖均有相关性（R<-0.06/R>0.06,P<0.05）。结论：严格的饮食控制及运动有助于控制2型糖尿病大鼠血糖水平的稳定,其可能与控制调节大鼠体内瘦素及脂联素水平有关。     

儿童单纯肥胖症血清瘦素、脂联素相关性研究及意义

目的:检测单纯肥胖症患儿血清中瘦素、脂联素水平,评价其临床意义.方法:依据儿童单纯肥胖症诊断标准选取40名患儿,男女各20名,选取20名年龄、性别类同的健康儿童作为对照组.应用ELISA法检测患儿血清瘦素及脂联素水平,与健康儿童进行比较及男女两组之间比较.结果:与对照组相比,患儿血清脂联素水平降低,瘦素水平升高,差异有统计学意义(P<0.05),男女两组比较,差异无统计学意义(P>0.05).结论:肥胖症儿童脂联素、瘦素水平的变化与儿童肥胖症发病密切相关,对儿童肥胖症的发展趋势及预后判断有一定意义,脂联素、瘦素素水平是肥胖发生的预测指标.     

脂肪细胞因子对代谢的调节

脂肪组织可将多余能量以甘油三酯(triglycerides,TG)形式储存,在饥饿状态下可分解TG产生游离脂肪酸(free fatty acids,FFAs)为机体供能。此外,脂肪组织还具有体温调节和器官保护功能,并且越来越多的证据表明,脂肪组织也是一种重要的内分泌组织。脂肪组织分泌的蛋白质物质被称为脂肪细胞因子(adipokine),可通过自分泌、旁分泌和内分泌方式发挥多种生物学功能,例如调节能量摄入和能量消耗,调节糖脂代谢,抗炎和促炎反应。对整体而言,脂肪细胞因子可调节大脑、肝、肌肉、血管系统、心、胰腺和免疫系统等不同靶器官的生物反应。其中,脂肪细胞因子在糖脂代谢中发挥特定的作用,包括:葡萄糖代谢[瘦素(leptin)、脂联素(adiponectin)、抵抗素(resistin)];胰岛素敏感性 [瘦素、脂联素、锌-α2-糖蛋白(zinc-α2-glycoprotein,ZAG)];脂肪形成[骨形成蛋白4(bone morphogenetic protein 4,BMP4)]等生物反应过程。但目前对脂肪组织功能障碍与代谢之间机制的理解尚不完善。脂肪组织功能发生紊乱时,脂肪细胞因子的分泌会发生改变,并可能导致一系列与肥胖相关的代谢性疾病的发生。临床前和临床研究表明,激活或抑制特定脂肪细胞因子的信号转导可能是一种适合干预代谢疾病的方法。本文就部分脂肪细胞因子对代谢的调控作用做出综述,以增强对脂肪细胞因子功能的理解。     

胸腺因子D对高密度脂蛋白和低密度脂蛋白的影响

老年人的HDL值为241.3±42.3mg/DL,比中青年低,老年人的LDL值为379.8±124.0mg/DL,比中青年高。胸腺因子D治疗后HDL升高,LDL下降,对乏力、易感冒、寐少、萎糜、纳差、咳痰等症状明显好转。     

新加越鞠丸对非酒精性脂肪肝大鼠血清脂联素及瘦素水平的影响

目的:观察新加越鞠丸对非酒精性脂肪肝大鼠血清脂联素及瘦素的影响.方法:3只健康雄性SD大鼠随机分为4组,每组9只.高脂高糖饲料喂养制备大鼠非酒精性脂肪肝模型.8W病理显示造模成功后,每组给予相应药物干预,连续4W.酶联免疫吸附(ELISA)法测定各组大鼠血清中脂联素(ADP)浓度及瘦素(LP)浓度,HE染色观察肝脏病理变化.结果:与正常对照组大鼠比较,模型对照组血清中ADP浓度明显降低(P＜0.05),LP明显升高(P＜0.05);与模型对照组大鼠比较,新加越鞠丸组血清中ADP浓度明显升高(P＜0.05),LP明显降低(P＜0.05);新加越鞠丸组大鼠较水林佳组,血清中ADP浓度显著升高(P＜0.05),LP有显著性差异(P＜0.05).结论:新加越鞠丸可通过升高血清脂联素水平,降低血清瘦素水平,减轻非酒精性脂肪肝的损伤.     

脂联素的信号转导通路

脂联素是一种由脂肪组织分泌的胶原样蛋白,其能降低血浆游离脂肪酸,具有抗动脉粥样硬化、改善胰岛素抵抗、降血糖、抗炎等作用,但其作用机制尚不十分明确。近期,脂联素的两型受体AdipoR1／R2已经被克隆,脂联素可能是通过其受体激活过氧化物酶体增殖物激活受体(PPAR)和AMPK信号转导通路而发挥作用。     

苯那普利联合氯沙坦治疗早期糖尿病肾病的临床研究

目的：研究苯那普利联合氯沙坦对2型糖尿病肾病（diabetic nephropathy,DN）患者肾功能以及血浆脂联素（adiponectin,APN）和高敏C反应蛋白（highsensitivity-C responseprotein,hs-CRP）的影响。方法：选择我院心血管内科住院的2型糖尿病肾病患者42例,均符合早期糖尿病肾病的诊断标准,给予苯那普利10-20mg治疗3个月后,给予苯那普利10mg联合氯沙坦50mg-100mg再治疗3个月,检测和比较治疗前后患者血肌酐（Scr）和24小时尿蛋白定量（24h—UPE）以及血浆hs-CRP和APN水平。结果：苯那普利治疗3个月后,患者的Scr、24h—UPE和hs-CRP水平较治疗前明显降低;血浆APN水平较治疗前明显升高,差异均有统计学意义（P〈0．05）。而苯那普利联合氯沙坦再治疗3个月后,患者的Scr、24h-UPE水平和hs-CRP水平较苯那普利治疗3月时更低,血浆APN水平较苯那普利治疗3个月时更高,差异均有统计学意义（P〈0．05）。结论：苯那普利联合氯沙坦治疗可更好地保护早期糖尿病肾病患者的肾功能,这可能与其提高血浆APN水平和降低CRP水平有关。     

脂蛋白质组学研究进展

脂蛋白质组学(lipoproteomics)是一门应用蛋白质组学技术对脂蛋白(lipoprotein)进行全面、系统地分析和鉴定,进而了解脂蛋白的组成和功能以及与相关疾病发生、发展之间关系的新兴学科.近些年来,脂蛋白质组学研究促进了脂蛋白中蛋白质组分的急性期响应、补体激活、免疫响应、炎症响应、蛋白酶抑制等新功能的发现,显示了广阔的应用前景.本文对脂蛋白的功能和分类,以及目前应用于脂蛋白质组学研究的脂蛋白分离方法和蛋白质鉴定方法进行了简述,并综述了高密度脂蛋白、低密度脂蛋白和极低密度脂蛋白的脂蛋白质组学研究,及其在冠状动脉疾病、糖尿病、类风湿性关节炎等疾病研究的最新进展.     

Relationship of plasma leptin and adiponectin concentrations with menopausal status in Tunisian women

To evaluate the effect of menopausal status and body mass index (BMI) on circulating leptin and adiponectin concentrations and investigate whether there is an influence of menopausal transition on the relationships of these adipokines and leptin to adiponectin (L/A) ratio with lipid profile and insulin resistance in a sample of Tunisian women. One hundred ninety-six premenopausal (mean age 35.3 ± 7.6 years) and 180 postmenopausal women (mean age 53.4 ± 6.2 years) were included in the study. Participants were stratified into obese and normal weight groups based upon their baseline BMI. Fasting glucose, HDL-cholesterol (HDL-C), triglycerides (TG), total cholesterol (TC), insulin, leptin, and adiponectin concentrations were measured. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Premenopausal women had significantly higher leptin and L/A ratio and lower adiponectin levels than postmenopausal women. Menopause had no effect on the mean values of BMI, insulin or HOMA-IR, HDL-C, and TG. Using a multiple linear regression model, menopausal status was identified, as significant independent predictor for leptin and adiponectin levels. Irrespective of the menopausal status, obese women exhibited higher leptin and L/A ratio and lower adiponectin levels compared to those with normal weight. Comparison between the two menopausal stages in obese and normal weight groups showed that leptin and L/A ratio decreased, while adiponectin increased from pre- to postmenopausal stage only in obese group. The L/A ratio correlated better with lipid profile and HOMA-IR in postmenopausal stage. The present study showed a significant interaction between menopause and BMI on leptin and adiponectin secretion. Menopausal transition affects the relationships of these adipokines with lipids and insulin resistance.     

Fat-cell mass,serum leptin and adiponectin changes during weight gain and loss in yellow-bellied marmots (<Emphasis Type="Italic">Marmota flaviventris</Emphasis>)

Leptin and adiponectin are proteins produced and secreted from white adipose tissue and are important regulators of energy balance and insulin sensitivity. Seasonal changes in leptin and adiponectin have not been investigated in mammalian hibernators in relationship to changes in fat cell and fat mass. We sought to determine the relationship between serum leptin and adiponectin levels with seasonal changes in lipid mass. We collected serum and tissue samples from marmots (Marmota flaviventris) in different seasons while measuring changes in fat mass, including fat-cell size. We found that leptin is positively associated with increasing fat mass and fat-cell size, while adiponectin is negatively associated with increasing lipid mass. These findings are consistent with the putative roles of these adipokines: leptin increases with fat mass and is involved in enhancing lipid oxidation while adiponectin appears to be higher in summer when hepatic insulin sensitivity should be maintained since the animals are eating. Our data suggest that during autumn/winter animals have switched from a lipogenic condition to a lipolytic state, which may include leptin resistance.Communicated by I.D. Hume     

Adiponectin is partially associated with exosomes in mouse serum

Exosomes are membrane vesicles 30–120 nm in diameter that are released by many cell types and carry a cargo of proteins, lipids, mRNA, and microRNA. Cultured adipocytes reportedly release exosomes that may play a role in cell-to-cell communication during the development of metabolic diseases. However, the characteristics and function of exosomes released from adipocytes in vivo remain to be elucidated. Clearly, adipocyte-derived exosomes could exist in the circulation and may be associated with adipocyte-specific proteins such as adipocytokines. We isolated exosomes from serum of mice by differential centrifugation and analyzed adiponectin, leptin, and resistin in the exosome fraction. Western blotting detected adiponectin but no leptin and only trace amounts of resistin in the exosome fraction. The adiponectin signal in the exosome fraction was decreased by proteinase K treatment and completely quenched by a combination of proteinase K and Triton X-100. Quantitative ELISA showed that the exosome fraction contains considerable amounts of adiponectin, but not leptin or resistin. The concentration of adiponectin in the serum and the ratio of adiponectin to total protein in the exosome fraction were lower in obese mice than in lean mice. These results suggest that a portion of adiponectin exists as a transmembrane protein in the exosomes in mouse serum. We propose adiponectin as a marker of exosomes released from adipocytes in vivo.     

Aberrant expressions of leptin and adiponectin receptor isoforms in chronic myeloid leukemia patients

Background

Leptin and adiponectin receptors mediate the role of leptin in stimulating the growth of leukemic cells and the protective function of adiponectin undertaken in several malignancies such as leukemia. In this study, we investigated the involvement of the expression of leptin and adiponectin receptors in chronic myeloid leukemia (CML) pathogenesis.

Methods

The expression of leptin receptor isoforms, OB-Rt, OB-Ra, and OB-Rb, and the expression of adiponectin receptors, AdipoR1 and AdipoR2, were measured as mRNA levels in two CML cell lines (K562 and Meg-01) and 20 CML patients and 24 healthy controls by using RT-PCR.

Results

OB-Rt and OB-Ra isoforms expression of the leptin receptors were found to be significantly lower in Meg-01 cell lines than K562 cells. All leptin receptors were downregulated in CML patients and more particularly OB-Rb level was found to be undetectably low in normal PBMC as well as in CML patients. AdipoR1 expression level was higher in Meg-01 than in K562, whereas AdipoR2 level was found to be unchanged in both cell lines. Interestingly, while AdipoR1 expression increased in CML patients, AdipoR2 decreased. Moreover, imatinib therapy did not affect both leptin and adiponectin isoform expressions.

Conclusion

While the decrease in leptin receptor levels in CML patients was confirmed, the increase in AdipoR1 levels and relevant decrease in AdipoR2 levels depicted their possible involvement in CML pathogenesis. This suggests different functions of adiponectin receptors in CML development.     

Lipid lowering and antioxidant effects of Amomum subulatum seeds (Family Zingiberaceae) in cholesterol fed rabbits

In the present study, hypolipidemic activity of fraction (50:50; CHCl₃:CH₃OH) of Amomum subulatum (Zingiberaceae) seeds was evaluated in cholesterol-fed rabbits. Hyperlipidemia induced by feeding atherogenic diet for 120 days resulted in a significant increase in serum total cholesterol, phospholipid and triglyceride levels when compared with control group. The levels of LDL and VLDL-cholesterol were increased significantly, but the HDL-cholesterol ratio was decreased. The changes in the antioxidant parameters were accompanied by an increase in lipid peroxidation and reduction in glutathione (GSH) and catalase activity. The level of lipid peroxidation was reduced whereas GSH content and catalase activity were elevated after the treatment with A. subulatum fraction at the dose level of 100 mg/kg.b.wt/day. A significant reduction was observed in total cholesterol, triglyceride, phospholipid, LDL and VLDL cholesterol where as HDL-cholesterol ratio was increased after administration of A. subulatum. The results of the present study indicate that fraction of A. subulatum possesses lipid-lowering and antioxidant activity and could be beneficial in the treatment of hyperlipidemia.     

The balance between leptin and adiponectin in the control of carcinogenesis - Focus on mammary tumorigenesis

A number of studies indicate that a growing list of cancers may be influenced by obesity. In obese individuals these cancers can be more frequent and more aggressive resulting in reduced survival. One of the most prominent and well characterized cancers in this regard is breast cancer. Obesity plays a complex role in breast cancer and is associated with increased inflammation, angiogenesis and alterations in serum levels of potential growth factors such as insulin, adiponectin, leptin and estrogen. Reduced levels of serum adiponectin have been reported in breast cancer patients compared to healthy controls, particularly in postmenopausal women and the level of adiponectin has been shown to be inversely associated with insulin resistance. The role of serum leptin levels in breast cancer appears to be more complex. Some studies have shown leptin to be increased in women with breast cancer but other studies have found leptin to be decreased or unchanged. This may be due to a number of confounding issues. We and others propose that it may be the levels of adiponectin and leptin as well as the balance of adiponectin and leptin that are the critical factors in breast and other obesity related cancer tumorigenesis. This review will focus on the current understanding of the interplay between obesity and the functions of leptin and adiponectin. It will then examine what is known about their potential roles in cancer particularly as pertains to breast cancer and how the ratio of adiponectin to leptin may play a role in tumorigenesis.