Oxidative stress and lipid peroxidation by-products at the crossroad between adipose organ dysregulation and obesity-linked insulin resistance

Obesity has been proposed as an energy balance disorder in which the expansion of adipose tissue (AT) leads to unfavorable health outcomes. Even though adiposity represents the most powerful driving force for the development of insulin resistance (IR) and type 2 diabetes, mounting evidence points to “adipose dysregulation”, rather than fat mass accrual per se, as a key pathophysiological trigger of the obesity-linked metabolic complications. The dysfunctional fat, besides hypertrophic adipose cells and inflammatory cues, displays a reduced ability to form new adipocytes from the undifferentiated precursor cells (ie, the preadipocytes). The failure of adipogenesis poses a “diabetogenic” milieu either by promoting the ectopic overflow/deposition of lipids in non-adipose targets (lipotoxicity) or by inducing a dysregulated secretion of different adipose-derived hormones (ie, adipokines and lipokines). This novel and provocative paradigm (“expandability hypothesis”) further extends current “adipocentric view” implicating a reduced adipogenic capacity as a missing link between “unhealthy” fat expansion and impairment of metabolic homeostasis.     

Differentiation of human adipose tissue SVF cells into cardiomyocytes

Progenitor cells have been extensively studied and therapeutically applied in tissue reconstructive therapy. Stromal vascular fraction (SVF) cells, which are derived from adipose tissue, may represent a potential source of the cells which undergo phenotypical differentiation into many lineages both in vitro as well as in vivo. The goal of this study was to check whether human SVF cells may differentiate into cardiomyocyte-like entities. Human SVF cells were induced to differentiate by their incubation in Methocult medium in the presence of SCF, IL-3 and IL-6. Morphological transformation of the cells was monitored using optical light microscope, whereas changes in expression of the genes typical for cardiac phenotype were measured by qRT-PCR. Incubation of the human SVF cells in the medium that promotes cardiomyocyte differentiation in vitro resulted in formation of myotubule-like structures accompanied by up-regulation of the myocardium-characteristic genes, such as GATA, MEF2C, MYOD1, but not ANP. Human SVF cells differentiate into cardiomyocyte-like cells in the presence of the certain set of myogenesis promoting cytokines.     

Obesity causes a shift in metabolic flow of gangliosides in adipose tissues

Obesity is associated with insulin resistance and a mild chronic inflammation in adipose tissues. Recent studies suggested that GM3 ganglioside mediates dysfunction in insulin signaling. However, it has not been determined the ganglioside profiling in adipose tissues of obese animals. Here, we for the first time examined semi-quantitative ganglioside profiles in the adipose tissues of high fat- and high sucrose-induced obese, diabetic C57BL/6J mice by TLC and HPLC/mass spectrometry. In control adipose tissues GM3 dominated with traces of GM1 and GD1a; obesity led to a dramatic increase in GM2, GM1, and GD1a with the GM3 content unchanged. Similar results were obtained in KK and KKAy mice. Adipocytes separated from stromal vascular cells including macrophages contained more of those gangliosides in KKAy mice than in KK mice. These results underscore those gangliosides in the pathophysiology of obesity-related diseases.     

Application of in vivo microdialysis to measure leptin concentrations in adipose tissue

Microdialysis is a relatively new in vivo sampling technique, which allows repeated collecting of interstitial fluid and infusion of effector molecules into the tissue without influencing whole body function. The possibility of using microdialysis catheter with a large-pore size dialysis membrane (100 kDa) to measure concentrations of the adipocyte-derived peptide hormone leptin in interstitial fluid of adipose tissue was explored. Krebs–Henseleit buffer with 40 g/l dextran-70 was used to prevent perfusion fluid loss across the dialysis membrane. The relative recovery of leptin in vitro was determined using CMA/65 microdialysis catheter (100 kDa cut-off, membrane length 30 mm; CMA, Stockholm, Sweden) and four perfusion rates were tested (0.5, 1.0, 2.0, 5.0 μl/min). Furthermore, the microdialysis catheter CMA/65 was inserted into subcutaneous abdominal adipose tissue of 11 healthy human subjects and leptin concentrations in the interstitial fluid of adipose tissue in vivo were measured. The present findings are the first documentation on the use of microdialysis to study local leptin concentrations in the interstitial fluid of adipose tissue.     

男性青少年脂肪组织分布与相对骨龄的关系——Fels追踪研究

本文对Fels追踪研究中8—17岁男性青少年的相对骨龄与脂肪分布类型之间的关系做了分析。按体重/身高~2调整后,如用每个年龄的三种皮褶厚度(ST)指数的均值表示脂肪分布类型的话,8—12岁时,脂肪分布类型呈外周型分布,但13岁后开始朝向心型发展呈全身性分布。如用肩胛下ST/(肩胛下ST+肱三头肌区ST)的比例表示的话,那么14—17岁时,相对骨龄早者(简称早组)与相对骨龄晚者(简称晚组)相比,前者有较明显的向心型分布倾向。13—14岁时,早组的上述比值的年增长明显大于晚组。但是,按脂肪分布类型指数等级的基线和体重/身高~2调整之后,7、11或14岁时的相对骨龄不能预测17岁时的脂肪分布类型指数的等级。所以,我们可以得出这样的结论:如按本文的比例指数加以定量的话,脂肪分布类型与男性青少年的相对骨龄只有微弱的关系。他们的脂肪分布类型可能与其它成熟指征(如男性青春期的第二性征)有明显的关系。     

Influence of Androgenicity on Adipocytes and Precursor Cells in Female Rats

We examined the effects of overexposure of testosterone (T) on fat cell morphology and adipocyte precursor pools in inguinal and retroperitoneal fat depots of ovariectomized rats. In both tissues peripubertal T decreased weights without affecting adipocyte mean cell size or the size distribution profiles, but adipocyte number was decreased by 65% in the inguinal and by 38% in the retroperitoneal depots. Immunofluorescent flow cytometry utilizing a specific antibody to rat adipose tissue lipoprotein lipase was used to quantify regional precursor cell populations. T sharply reduced the percentages of differentiated and undifferentiated preadipocytes in the inguinal depot, from 43.2 ± 5.3 to 23.5 ± 2.1% and from 57.7 ± 4.0 to 43.6 ± 5.3%, respectively, with a concomitant increase in fibroblasts from 1.6 to 32.9%. On the other hand, T had no effect on retroperitoneal preadipocyte pools. Perinatal andro-genization exacerbated the decline in the inguinal weight (1.4 ± 0.1 vs. 2.2 ± 0.1g) but otherwise did not influence the actions of peripubertal T. Androgens may thus act in a tissue-specific manner to regulate fat cell growth potential in the femoral region in the female.     

Pro-fibrotic activity of lysophosphatidic acid in adipose tissue: In vivo and in vitro evidence

Lysophosphatidic acid (LPA) is a pro-fibrotic mediator acting via specific receptors (LPARs) and is synthesized by autotaxin, that increases with obesity. We tested whether LPA could play a role in adipose tissue (AT)-fibrosis associated with obesity. Fibrosis [type I, III, and IV collagens (COL), fibronectin (FN), TGFβ, CTGF and αSMA] and inflammation (MCP1 and F4/80) markers were quantified: (i) in vivo in inguinal (IAT) and perigonadic (PGAT) AT from obese-diabetic db/db mice treated with the LPAR antagonist Ki16425 (5 mg/kg/day ip for 7 weeks); and (ii) in vitro in human AT explants in primary culture for 72 h in the presence of oleoyl-LPA (10 μM) and/or Ki16425 (10 μM) and/or the HIF-1α inhibitor YC-1 (100 μM). Treatment of db/db mice with Ki16425 reduced Col I and IV mRNAs in IAT and PGAT while Col III mRNAs were only reduced in IAT. This was associated with reduction of COL protein staining in both IAT and PGAT. AT explants showed a spontaneous and time-dependent increase in ATX expression and production of LPA in the culture medium, along with increased levels of Col I and III, TGFβ and αSMA mRNAs and of COL protein staining. In vitro fibrosis was blocked by Ki16425 and was further amplified by oleoyl-LPA. LPA-dependent in vitro fibrosis was blocked by co-treatment with YC1. Our results show that endogenous and exogenous LPA exert a pro-fibrotic activity in AT in vivo and in vitro. This activity could be mediated by an LPA1R-dependent pathway and could involve HIF-1α.     

The effect of maternal omega-3 long-chain polyunsaturated fatty acid (n-3 LCPUFA) supplementation during pregnancy and/or lactation on body fat mass in the offspring: a systematic review of animal studies

Dietary n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) reduce adipogenesis and lipogenesis in adult rodents, but it is not clear whether an increased n-3 LCPUFA supply during the perinatal period influences body fat mass in the offspring. This systematic review aimed to evaluate the existing evidence from animal studies, which have addressed this question. Medline was searched for relevant articles. Studies were included if they involved maternal n-3 PUFA or LCPUFA supplementation and measured fat mass in the offspring. The design and quality of each study was assessed. Only four animal studies met our inclusion criteria. Three studies reported a lower fat mass in offspring of n-3 LCPUFA supplemented dams, however only one of these studies confined the intervention to the perinatal period. The dose of n-3 PUFA, the nature of the control treatment, the approaches used and outcomes assessed differed between studies. This review highlights the paucity of robust animal data as to the effect of increased n-3 LCPUFA exposure during the perinatal period alone, on body fat mass in the offspring and calls for further studies.     

脂肪间质干细胞研究进展

脂肪间质干细胞,是脂肪组织中一类多能性干细胞。其在体外特定的培养条件下,可诱导分化形成脂肪、骨、软骨、肌肉等组织类型细胞。人体脂肪组织十分丰富,用其分离脂肪间质干细胞可避免分离胚胎干细胞所面临的道德伦理问题和获取极少量骨髓分离骨髓间质干细胞时给供者带来极大痛苦等。因此脂肪间质干细胞可作为组织再生工程的干细胞理想的替代资源。本文重点论述脂肪间质干细胞的研究进展,并探讨其临床应用前景。     

驱动蛋白-1在小鼠脂肪组织糖脂代谢中的作用研究

目的:本文旨在探讨动物体内水平驱动蛋白-1在脂肪组织糖、脂代谢中的作用。方法:通过Cre/Loxp重组系统构建脂肪组织特异性敲除驱动蛋白-1的小鼠模型,在生理水平观察驱动蛋白-1表达缺陷对小鼠糖代谢、脂代谢和脂肪因子分泌的影响。结果:与六月龄对照组小鼠相比,同月龄驱动蛋白-1敲除小鼠的体重、脂肪组织重量和空腹血糖水平没有显著差异,但是其血清胰岛素水平显著升高;使用葡萄糖耐量试验(GTT)和胰岛素耐量实验(ITT)对小鼠的糖代谢水平进行评估,结果显示驱动蛋白-1敲除小鼠表现为葡萄糖不耐受、胰岛素不耐受;进一步血清检测显示驱动蛋白-1敲除小鼠表现为高甘油三酯血症和血清脂联素水平降低。结论:驱动蛋白-1在脂肪组织中参与调节糖、脂代谢过程,其表达或功能障碍是2型糖尿病等代谢性疾病的一个重要的发病因素。     

分离与培养人脂肪组织间充质干细胞的研究

目的：探索人脂肪组织源性间充质干细胞（ASCs）的分离、体外培养,为其广泛应用提供实验依据。方法：无菌条件下获取腹部手术病人皮下脂肪组织,酶消化法分离、培养ASCs,观察细胞形态并绘制细胞生长曲线,计算细胞群体倍增时间;对第2代细胞进行免疫组织化学染色,鉴定其表面分子CD44表达;取2—4代细胞用含体积分数为10％胎牛血清、1％青链霉素原液、1μmmol／L地塞米松、10μmmol／L胰岛素、0．5mmmol／LIBMX的高糖DMEM培养基中诱导培养一周,观察细胞形态变化,并用油红“O”染色定性。结果：人脂肪组织中含有大量间充质干细胞,呈成纤维细胞样贴壁生长,细胞群体倍增时间为55h左右;免疫化学染色鉴定CD44阳性;成脂诱导分化一周,可见细胞内有大量脂滴,油红“0”染色可见胞浆内有大量红染颗粒。结论：建立了一种自人体脂肪组织分离,培养ASCs经济简便的方法,为其能够作为组织工程理想的种子细胞及广泛应用于临床提供实验依据。     

Cardiac progenitor cells in brown adipose tissue repaired damaged myocardium

Cardiomyocyte (CM) regeneration is limited in adult life and is not sufficient to prevent myocardial infarction. Hence, the identification of a useful source of CM progenitors is of great interest for possible use in regenerative therapy. Mesenchymal stem cells in bone marrow, embryonic stem cells, and skeletal myoblasts are known sources of CM repletion; however, there are a number of critical problems for clinical application. In this study, we succeeded to identify CM progenitor cells in brown adipose tissue (BAT). Moreover, we showed that CM progenitor cells in BAT that existed in CD29-positive population could differentiate into CM with high efficiency. To confirm the in vivo effect of CD29(+)BAT-derived cells (BATDCs), we transplanted these cells into infarct border zone of an acute myocardial infarction model in rat. Results clearly indicated that implantation of CD29(+) BATDCs led to the reduction of the infarction area and improvement of left ventricular function by replacing newly developed CMs in comparison with that by CD29(+) white adipose tissue-derived cells or control saline. These findings suggest that BATDCs are one of the useful sources for a new strategy in CM regeneration.